50 results on '"R. Kuntz"'
Search Results
2. Frame-by-Frame Video Analysis of Idiosyncratic Reach-to-Grasp Movements in Humans
- Author
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Layne A Lenhart, Ian Q. Whishaw, Jessica R. Kuntz, and Jenni M. Karl
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Male ,Computer science ,General Chemical Engineering ,Video Recording ,Kinematics ,050105 experimental psychology ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,0302 clinical medicine ,Stimulus modality ,Match moving ,Human–computer interaction ,Humans ,0501 psychology and cognitive sciences ,Protocol (object-oriented programming) ,Behavior ,Hand Strength ,General Immunology and Microbiology ,Event (computing) ,Movement (music) ,General Neuroscience ,05 social sciences ,GRASP ,Frame (networking) ,Female ,Psychomotor Performance ,030217 neurology & neurosurgery - Abstract
Prehension, the act of reaching to grasp an object, is central to the human experience. We use it to feed ourselves, groom ourselves, and manipulate objects and tools in our environment. Such behaviors are impaired by many sensorimotor disorders, yet our current understanding of their neural control is far from complete. Current technologies for investigating human reach-to-grasp movements often utilize motion tracking systems that can be expensive, require the attachment of markers or sensors to the hands, impede natural movement and sensory feedback, and provide kinematic output that can be difficult to interpret. While generally effective for studying the stereotypical reach-to-grasp movements of healthy sighted adults, many of these technologies face additional limitations when attempting to study the unpredictable and idiosyncratic reach-to-grasp movements of young infants, unsighted adults, and patients with neurological disorders. Thus, we present a novel, inexpensive, and highly reliable yet flexible protocol for quantifying the temporal and kinematic structure of idiosyncratic reach-to-grasp movements in humans. High speed video cameras capture multiple views of the reach-to-grasp movement. Frame-by-frame video analysis is then used to document the timing and magnitude of pre-defined behavioral events such as movement start, collection, maximum height, peak aperture, first contact, and final grasp. The temporal structure of the movement is reconstructed by documenting the relative frame number of each event while the kinematic structure of the hand is quantified using the ruler or measure function in photo editing software to calibrate 2 dimensional linear distances between two body parts or between a body part and the target. Frame-by-frame video analysis can provide a quantitative and comprehensive description of idiosyncratic reach-to-grasp movements and will enable researchers to expand their area of investigation to include a greater range of naturalistic prehensile behaviors, guided by a wider variety of sensory modalities, in both healthy and clinical populations.
- Published
- 2018
3. Valganciclovir for the Suppression of Epstein-Barr Virus Replication
- Author
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Amalia Magaret, Corey Casper, Steven R. Kuntz, Stacy Selke, Lawrence Corey, Jessica E Yager, Meei-Li Huang, and Anna Wald
- Subjects
0301 basic medicine ,Ganciclovir ,Adult ,Male ,Washington ,Herpesvirus 4, Human ,Mononucleosis ,medicine.disease_cause ,Virus Replication ,Antiviral Agents ,Virus ,Post-transplant lymphoproliferative disorder ,03 medical and health sciences ,Young Adult ,Double-Blind Method ,Immunology and Allergy ,Medicine ,Humans ,Valganciclovir ,Infectious Mononucleosis ,Viral shedding ,Aged ,business.industry ,Middle Aged ,Viral Load ,medicine.disease ,Epstein–Barr virus ,Virus Shedding ,030104 developmental biology ,Infectious Diseases ,Immunology ,Brief Reports ,business ,Viral load ,medicine.drug - Abstract
Epstein-Barr virus (EBV) causes infectious mononucleosis and can lead to lymphoproliferative diseases. We evaluated the effects of valganciclovir on oral EBV shedding in a randomized, double-blind, placebo-controlled study. Twenty-six men received oral valganciclovir or daily placebo for 8 weeks, followed by a 2-week "washout period" and then 8 weeks of the alternative treatment. Valganciclovir reduced the proportion of days with EBV detected from 61.3% to 17.8% (relative risk, 0.28; 95% confidence interval [CI], .21-.41; P < .001), and quantity of virus detected by 0.77 logs (95% CI, .62-.91 logs; P < .001). Further investigations into the impact of valganciclovir on EBV-associated diseases are needed.
- Published
- 2017
4. The syntactic organization of pasta-eating and the structure of reach movements in the head-fixed mouse
- Author
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Ian Q. Whishaw, Gerlinde A. S. Metz, Majid H. Mohajerani, Jessica R. Kuntz, Jamshid Faraji, and Behroo Mirza Agha
- Subjects
0301 basic medicine ,Male ,Computer science ,Head (linguistics) ,lcsh:Medicine ,Article ,03 medical and health sciences ,Mice ,0302 clinical medicine ,Animals ,lcsh:Science ,Communication ,Multidisciplinary ,Behavior, Animal ,business.industry ,musculoskeletal, neural, and ocular physiology ,lcsh:R ,food and beverages ,Feeding Behavior ,Numerical digit ,body regions ,030104 developmental biology ,Biting ,lcsh:Q ,Artificial intelligence ,business ,030217 neurology & neurosurgery ,psychological phenomena and processes ,Psychomotor Performance - Abstract
Mice are adept in the use of their hands for activities such as feeding, which has led to their use in investigations of the neural basis of skilled-movements. We describe the syntactic organization of pasta-eating and the structure of hand movements used for pasta manipulation by the head-fixed mouse. An ethogram of mice consuming pieces of spaghetti reveals that they eat in bite/chew bouts. A bout begins with pasta lifted to the mouth and then manipulated with hand movements into a preferred orientation for biting. Manipulation involves many hand release-reach movements, each with a similar structure. A hand is advanced from a digit closed and flexed (collect) position to a digit extended and open position (overgrasp) and then to a digit closed and flexed (grasp) position. Reach distance, hand shaping, and grasp patterns featuring precision grasps or whole hand grasps are related. To bite, mice display hand preference and asymmetric grasps; one hand (guide grasp) directs food into the mouth and the other stabilizes the pasta for biting. When chewing after biting, the hands hold the pasta in a symmetric resting position. Pasta-eating is organized and features structured hand movements and so lends itself to the neural investigation of skilled-movements.
- Published
- 2017
5. A Critical Component of Meiotic Drive in Neurospora Is Located Near a Chromosome Rearrangement
- Author
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Patrick K. T. Shiu, David G. Rehard, Kevin J. Sharp, Thomas M. Hammond, Katie M. Groskreutz, Danielle R. Kuntz, and Austin M. Harvey
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Genes, Fungal ,Molecular Sequence Data ,Locus (genetics) ,Chromosomal rearrangement ,Investigations ,Biology ,Neurospora ,Meiosis ,Genetics ,DNA, Fungal ,Gene Rearrangement ,Base Sequence ,fungi ,Chromosome Mapping ,Sequence Analysis, DNA ,Gene rearrangement ,Spores, Fungal ,biology.organism_classification ,Meiotic drive ,Genetic Loci ,Mutation ,Chromosomes, Fungal ,Recombination ,Genetic screen - Abstract
Neurospora fungi harbor a group of meiotic drive elements known as Spore killers (Sk). Spore killer-2 (Sk-2) and Spore killer-3 (Sk-3) are two Sk elements that map to a region of suppressed recombination. Although this recombination block is limited to crosses between Sk and Sk-sensitive (SkS) strains, its existence has hindered Sk characterization. Here we report the circumvention of this obstacle by combining a classical genetic screen with next-generation sequencing technology and three-point crossing assays. This approach has allowed us to identify a novel locus called rfk-1, mutation of which disrupts spore killing by Sk-2. We have mapped rfk-1 to a 45-kb region near the right border of the Sk-2 element, a location that also harbors an 11-kb insertion (Sk-2INS1) and part of a >220-kb inversion (Sk-2INV1). These are the first two chromosome rearrangements to be formally identified in a Neurospora Sk element, providing evidence that they are at least partially responsible for Sk-based recombination suppression. Additionally, the proximity of these chromosome rearrangements to rfk-1 (a critical component of the spore-killing mechanism) suggests that they have played a key role in the evolution of meiotic drive in Neurospora.
- Published
- 2014
6. Reduced human herpesvirus-8 oropharyngeal shedding associated with protease inhibitor-based antiretroviral therapy
- Author
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Ashok Cattamanchi, Lawrence Corey, Meei Li Huang, Anna Wald, Corey Casper, Soren Gantt, Elizabeth M Krantz, Stacy Selke, Steven R. Kuntz, and Amalia Magaret
- Subjects
Adult ,Male ,Washington ,viruses ,medicine.medical_treatment ,HIV Infections ,Article ,Young Adult ,immune system diseases ,Antiretroviral Therapy, Highly Active ,Nasopharynx ,Virology ,Humans ,HIV Protease Inhibitor ,Medicine ,Protease inhibitor (pharmacology) ,Prospective Studies ,Viral shedding ,Aged ,Protease ,business.industry ,virus diseases ,HIV Protease Inhibitors ,Herpesviridae Infections ,Middle Aged ,Viral Load ,biochemical phenomena, metabolism, and nutrition ,medicine.disease ,Antiretroviral therapy ,Virus Shedding ,Infectious Diseases ,DNA, Viral ,Herpesvirus 8, Human ,Immunology ,Female ,Sarcoma ,business ,Viral load ,Human herpesvirus - Abstract
Human herpesvirus 8 (HHV-8) replication increases the risk of Kaposi sarcoma (KS). Highly-active antiretroviral therapy (HAART) reduces the incidence of KS, and regimens that contain protease inhibitors (PIs) may be particularly effective.To determine whether PI-based HAART regimens may more effectively inhibit HHV-8 shedding compared to regimens without PIs.Prospective, observational study of 142 HIV-1 and HHV-8 co-infected men conducted in Seattle, Washington. Quantitative HHV-8 PCR testing was performed on daily swabs of the oropharynx, the primary site of HHV-8 replication. Associations between antiretroviral regimen and detection of HHV-8 DNA in swabs were evaluated using generalized estimating equations.HHV-8 DNA was detected in 3016 (26%) of 11,608 specimens collected. PI-based HAART was associated with a statistically significantly lower frequency of detection (RR 0.2; 95% CI 0.1-0.5) compared to ART-naïve persons, whereas HAART without a PI was not (RR 0.7; 95% CI 0.4-1.3). Compared to ART-naïve persons, there was also a trend toward lower quantities of HHV-8 detected during treatment with HAART regimens that contained a PI. These associations between PIs and measures of HHV-8 shedding could not be attributed to use of nelfinavir, which inhibits HHV-8 replication in vitro, and were independent of CD4 count and HIV plasma viral load (VL).HAART regimens that contain PIs appear to decrease HHV-8 shedding compared to NNRTIs. Further study of PI-based HAART is warranted to determine the optimal regimens for prevention and treatment of KS.
- Published
- 2014
7. Characterizing Ethical Cases: A Cross-Cultural Investigation of Individual Differences, Organisational Climate, and Leadership on Ethical Decision-Making
- Author
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Detelin Elenkov, Anna Nabirukhina, J. R. Kuntz, and Joana Kuntz
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Economics and Econometrics ,Ethical decision ,General Business, Management and Accounting ,Cross-cultural studies ,Ethical leadership ,Identification (information) ,Arts and Humanities (miscellaneous) ,Ethical dilemma ,Cross-cultural ,Ethical climate ,Sociology ,Business and International Management ,Business ethics ,Law ,Social psychology - Abstract
The primary purpose of this study was to explore the unique impact of individual differences (e.g. gender, managerial experience), social culture, ethical leadership, and ethical climate on the manner in which individuals analyse and interpret an organisational scenario. Furthermore, we sought to explore whether the manner in which a scenario is initially interpreted by respondents (i.e. as a legal issue, ethical issue, and/or ethical dilemma) influenced subsequent recognition of the relevant stakeholders involved and the identification of intra- and extra-organisational variables significant to the scenario depicted. Data for this study were anonymously collected from professional samples in Russia (Moscow region) and in New Zealand. Findings show a strong effect of social culture (i.e. working in New Zealand or working in Russia) on the manner in which respondents characterised the scenario, on the experience of ethical climate and ethical leadership in their organisations, and on the ability to identify intra- and extra-organisational variables responsible for the situation presented in the scenario, above and beyond other individual and contextual factors.
- Published
- 2012
8. Surveying Philosophers About Philosophical Intuition
- Author
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J. R. Kuntz and Joana Kuntz
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Philosophy of mind ,Philosophy of science ,Theoretical definition ,Globe ,Experimental and Cognitive Psychology ,Epistemology ,Philosophy ,medicine.anatomical_structure ,medicine ,Philosophical theory ,Psychology ,Experimental philosophy ,Intuition ,Philosophical methodology - Abstract
This paper addresses the definition and the operational use of intuitions in philosophical methods in the form of a research study encompassing several regions of the globe, involving 282 philosophers from a wide array of academic backgrounds and areas of specialisation. The authors tested whether philosophers agree on the conceptual definition and the operational use of intuitions, and investigated whether specific demographic variables and philosophical specialisation influence how philosophers define and use intuitions. The results obtained point to a number of significant findings, including that philosophers distinguish between intuitions used to formulate (discovery) and to test (justification) philosophical theory. The survey results suggest that strategies implemented to characterise philosophical intuition are not well motivated since, even though philosophers do not agree on a single account of intuition, they fail to capture a preferred usage of intuitions as aspects of discovery. The quantitative summary of survey findings informs the debate on this topic, and advances more defined routes for subsequent approaches to the study of intuitions.
- Published
- 2011
9. Rapidly Cleared Episodes of Oral and Anogenital Herpes Simplex Virus Shedding in HIV-Infected Adults
- Author
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Steven R. Kuntz, Stacy Selke, Anna Wald, Lawrence Corey, Meei Li Huang, Amalia Magaret, and Karen E. Mark
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Adult ,Male ,Herpesvirus 2, Human ,viruses ,Anal Canal ,HIV Infections ,Herpesvirus 1, Human ,medicine.disease_cause ,Polymerase Chain Reaction ,Article ,Virus ,Herpesviridae ,medicine ,Humans ,Pharmacology (medical) ,Viral shedding ,Sida ,Herpes Genitalis ,Herpes Labialis ,Mouth ,biology ,Herpes Simplex ,Middle Aged ,biology.organism_classification ,Virus Shedding ,Infectious Diseases ,Herpes simplex virus ,DNA, Viral ,Immunology ,Female ,Virus Activation ,Viral disease - Abstract
Objective: To determine whether rapidly cleared episodes of herpes simplex virus (HSV) reactivation occur in HIV-infected adults. Methods: Twenty HSV-2―seropositive, HIV-seropositive adults, including 9 (45%) who were also HSV-1 seropositive, collected oral and anogenital swabs for HSV DNA polymerase chain reaction 4 times a day for 60 days. Samples were positive for HSV if we detected ≥150 copies of HSV DNA/mL of specimen. Results: Median HSV shedding episode duration was 7.5 (range 4-253) hours for oral and 11 (range 4-328) hours for anogenital reactivation. Thirty-five percent of oral and 29% of anogenital reactivations lasted ≤6 hours, and 59% of oral and 53% of anogenital reactivations lasted ≤12 hours. Seven of 9 participants who shed orally and 10 of 15 who shed anogenitally had ≥1 reactivation lasting ≤6 hours. The median maximum level of HSV DNA detected in an episode increased with episode duration for both oral and anogenital episodes. Concurrent oral and anogenital shedding occurred more frequently than expected: oral HSV shedding was detected on 17% of time points with anogenital but 1% of time points without anogenital, shedding (P < 0.001). Conclusions: Rapidly cleared episodes of oral and anogenital HSV shedding occur in HIV-infected persons, supporting the hypothesis that frequent anogenital mucosal immune activation caused by HSV-2 is present in HIV coinfected persons, potentially contributing to HIV infectiousness.
- Published
- 2010
10. Exploring the Effect of Obscurants on Safe Landing Zone Identification
- Author
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Noah R. Kuntz, Keith W. Sevcik, and Paul Y. Oh
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Engineering ,business.industry ,Mechanical Engineering ,Firefighting ,Environment controlled ,ComputerApplications_COMPUTERSINOTHERSYSTEMS ,Terrain ,Field tests ,Industrial and Manufacturing Engineering ,Identification (information) ,Artificial Intelligence ,Control and Systems Engineering ,Landing zone ,Range (aeronautics) ,Systems engineering ,Electrical and Electronic Engineering ,business ,Software ,Simulation ,Verification and validation - Abstract
Manned rotorcraft are often employed in harsh environments and difficult terrain that are inaccessible to other craft. Conversely, robotic rotorcraft are operated in controlled settings, often at safe, high altitudes. Missions such as cargo delivery, medevac and fire fighting are unachievable because of unpredictable adverse environmental conditions. To enable UAVs to perform these missions, the effects of obscurants on UAV sensor suites and algorithms must be clearly understood. This paper explores the use of a laser range finder to accomplish landing zone identification in unknown, unstructured environments. The ability to detect a landing zone in environments obscured by smoke is investigated. This is accomplished using a design methodology of testing and evaluating in a controlled environment followed by verification and validation in the field. This methodology establishes a concrete understanding of the sensor performance, thereby removing ambiguities in field tests.
- Published
- 2009
11. Cost-effectiveness of distal embolic protection for patients undergoing percutaneous intervention of saphenous vein bypass graftsResults from the SAFER trial
- Author
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D COHEN, S MURPHY, D BAIM, T LAVELLE, R BEREZIN, D CUTLIP, K HO, and R KUNTZ
- Subjects
Cardiology and Cardiovascular Medicine - Published
- 2004
12. Frequent Reactivation of Herpes Simplex Virus among HIV‐1–Infected Patients Treated with Highly Active Antiretroviral Therapy
- Author
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Elizabeth M Krantz, Anna Wald, Lawrence Corey, Christine M. Posavad, Steven R. Kuntz, Stacy Selke, and Meei Li Huang
- Subjects
Adult ,Male ,Simplexvirus ,food.ingredient ,Herpesvirus 2, Human ,viruses ,HIV Infections ,medicine.disease_cause ,Virus ,Herpesviridae ,food ,Antiretroviral Therapy, Highly Active ,Alphaherpesvirinae ,medicine ,Humans ,Immunology and Allergy ,Genitalia ,Sida ,Herpes Genitalis ,Mucous Membrane ,biology ,business.industry ,Mouth Mucosa ,Herpes Simplex ,Middle Aged ,biology.organism_classification ,Virology ,Virus Shedding ,Infectious Diseases ,Herpes simplex virus ,Anti-Retroviral Agents ,DNA, Viral ,HIV-2 ,Immunology ,HIV-1 ,Female ,Viral disease ,business - Abstract
The effect of highly active antiretroviral therapy (HAART) on control of herpes simplex virus (HSV) in human immunodeficiency virus (HIV) type 1– infected subjects is not known. Among 28 HAART-treated and 49 untreated subjects with HIV-1 and HSV-2 infections mucosal HSV shedding (median 18% and 29% of days positive for HSV DNA respectively; P = .08) and HSV DNA level (median 56250 and 50000 copies/mL respectively; P = .20) were similar. Treated subjects reported significantly fewer days with HSV lesions compared with untreated subjects (2.8% vs. 11.3% of days respectively; P = .001). Thus mucosal HSV shedding and HSV-2 reactivation were still frequent among treated subjects even though HAART was associated with fewer days with HSV lesions. (authors)
- Published
- 2004
13. A cerebellar-like terminal and postural tremor induced in normal man by transcranial magnetic stimulation
- Author
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Helge Topka, S. Mescheriakov, L. Seydel, Andreas Boose, R. Kuntz, J. Rothwell, Ingo Hertrich, and Johannes Dichgans
- Subjects
Adult ,Male ,Wrist Joint ,Cerebellum ,Multiple Sclerosis ,Cerebellar Ataxia ,medicine.medical_treatment ,Posture ,Motor Activity ,Reference Values ,Parietal Lobe ,Tremor ,Humans ,Medicine ,Leg ,Electromyography ,business.industry ,Body movement ,Somatosensory Cortex ,Postural tremor ,Middle Aged ,Evoked Potentials, Motor ,Transcranial Magnetic Stimulation ,Action tremor ,Electric Stimulation ,Biomechanical Phenomena ,nervous system diseases ,body regions ,Transcranial magnetic stimulation ,Forearm ,medicine.anatomical_structure ,Brain stimulation ,Intention tremor ,Neurology (clinical) ,Voluntary musculoskeletal movement ,medicine.symptom ,business ,Neuroscience - Abstract
Trains of repetitive transcranial magnetic stimulation (TMS) at 10-30 Hz and intensities of 90-120% motor threshold were delivered through a figure of eight coil over the motor cortex while normal subjects made either rapid, self-terminated (ballistic) wrist movements or maintained the position of their wrist at a fixed angle. Movement kinematics and EMG activity in antagonistic forearm muscles were analysed. In the ballistic task, repetitive TMS had little effect on the velocity or acceleration of the initial segment of the movement, although it induced large terminal oscillations (tremor) around the target position at frequencies between 4.4 and 7.2 Hz. The likelihood that tremor would occur increased with increasing stimulus intensities or frequencies. It was maximal with stimulation over the forearm area, and decreased with stimulation over the leg area, or over parietal sites; there was no tremor during stimulation of cervical nerve roots. The frequency of the induced tremor was independent of the rate of stimulation and did not depend on the presence of excitatory and inhibitory motor responses to the stimulus. Stimulation could also induce tremor of the same frequency in the fixed task, but only during co-contraction of forearm muscles. The amplitude of tremor was proportional to the level of co-contraction. Clinically, the tremor induced by repetitive TMS appeared very similar to cerebellar tremors. In order to confirm this we investigated two cerebellar patients, one with autosomal dominant cerebellar ataxia and the other with multiple sclerosis. Both of them had a terminal tremor of 6-7 Hz in the wrist movement task. In the holding task, the amplitude of their postural tremor increased with the level of co-contraction in forearm muscles. Since the frequency of repetitive TMS-induced tremor was independent of stimulus parameters, we conclude that it represents some intrinsic property of the CNS. We suggest that the tremor is caused by disruption of cortical processes involved in terminating a voluntary movement or maintaining a posture. Similarities to cerebellar patients suggest that repetitive TMS may cause tremor by interfering with adaptive cerebellar afferent inflow to motor cortex. Repetitive TMS-induced tremor, therefore, may represent a model of some forms of cerebellar tremor in man.
- Published
- 1999
14. Chemistry of Bifunctional Photoprobes.1 3. Correlation between the Efficiency of CH Insertion by Photolabile Chelating Agents and Lifetimes of Singlet Nitrenes by Flash Photolysis: First Example of Photochemical Attachment of 99mTc−Complex with Human Serum Albumin
- Author
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Wynn A. Volkert, Matthew S. Platz, Raghoottama S. Pandurangi, Jacek Rogowski, Robert R. Kuntz, and Przemyslaw Lusiak
- Subjects
chemistry.chemical_compound ,chemistry ,Cyclohexane ,Nitrene ,Amide ,Organic Chemistry ,Flash photolysis ,Chelation ,Singlet state ,Azide ,Bifunctional ,Photochemistry - Abstract
Systematic functionalization of perfluoroaryl azides with chelating agents capable of complexing transition metals produces a new class of bifunctional photolabile chelating agents (BFPCAs). The strategy to shield the azide functionality from the electronic and steric influence of the electron-rich metal Pd through ester and amide bridges raised CH insertion efficiency to unprecedented levels (>92%) in a model solvent (cyclohexane). In contrast, perfluoroaryl azides attached to chelating agents via hydrazones show no significant CH insertion in cyclohexane upon photolysis. Measurements of the lifetimes of the singlet nitrenes derived from these agents by flash photolysis techniques correlate well with the efficiency of CH insertion by demonstrating longer lifetimes (10−50 times) for singlet nitrenes derived from azidotetrafluorinated esters and amides compared with the related hydrazones, which failed to yield significant CH insertion. A representative BFPCA 12 is chelated to diagnostic radionuclide 99mTc...
- Published
- 1998
15. Chemistry of Bifunctional Photoprobes
- Author
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Surbhi Desai, Robert R. Kuntz, Raghoottama S. Pandurangi, and Przemyslaw Lusiak
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biology ,Chromogenic ,Nitrene ,Organic Chemistry ,Conjugated system ,Biochemistry ,Combinatorial chemistry ,Horseradish peroxidase ,Small molecule ,chemistry.chemical_compound ,Biotin ,chemistry ,Yield (chemistry) ,Drug Discovery ,biology.protein ,Organic chemistry ,Bifunctional ,Molecular Biology - Abstract
Synthesis of a new photo cross-linking agent incorporating chromogenicity, cleavability, and water solubility is described. The high efficiency of nitrene insertion observed upon photolysis of perfluoroaryl azides into organic solvents and proteins is extended to the design and synthesis of new multifunctional cross-linking agents useful for protein–protein interactions. The new cross-linker sulfosuccinimidyl (perfluorobenzamido)-ethyl-1,3′-dithiopropionate (SFAD) 10 was conjugated to IgG and cross-linked to horseradish peroxidase (HRP). The analysis of the cross-linked product using ELISA assays leads to a higher yield of IgG–HRP cross-linked product than that seen with a similar nonfluorinated analog. The efficiency of photo cross-linking by SFAD is also extended to small molecule biotin via CH insertion and checked for the retention of binding affinity of the cross-linked product.
- Published
- 1998
16. The photoreduction of acetylene by band-gap irradiation of TiO2 using Mo2O4 (diethyldithiocarbamate)2 as a catalyst
- Author
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Robert R. Kuntz
- Subjects
Reaction mechanism ,Chemistry ,Band gap ,General Chemical Engineering ,General Physics and Astronomy ,Substrate (chemistry) ,General Chemistry ,Photochemistry ,Catalysis ,Colloid ,chemistry.chemical_compound ,Acetylene ,Photocatalysis ,Molecule - Abstract
The photoreduction of acetylene is catalyzed by Mo 2 O 4 (dedtc) 2 (dedtc, diethyldithiocarbamate) in the presence of 5–8 nm diameter colloidal TiO 2 . This photocatalytic process exhibits optimum activity at pH 6 and a loading of 30 catalyst molecules per TiO 2 particle. The same catalytic site(s) are responsible for C 2 H 2 reduction to C 2 H 4 and C 2 H 6 and H + reduction to H 2 . The overall photonic efficiency is 1.3% for the transfer of reducing equivalents to products at full lamp intensity, and increases with decreasing intensity. The effects of pH, temperature, intensity and loading on the catalytic process are consistent with a mechanism in which the catalytic site associated with the TiO 2 surface promotes the transfer of H atoms or electrons to the bound substrate. The photocatalytic properties of this neutral molecular complex are compared with those observed for other Mo-containing catalysts.
- Published
- 1997
17. Chemistry of Bifunctional Photoprobes. 1. Perfluoroaryl Azido Functionalized Phosphorus Hydrazides as Novel Photoreactive Heterobifunctional Chelating Agents: High Efficiency Nitrene Insertion on Model Solvents and Proteins
- Author
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Wynn A. Volkert, Srinivasa R. Karra, Kattesh V. Katti, Raghoottama S. Pandurangi, and Robert R. Kuntz
- Subjects
chemistry.chemical_compound ,chemistry ,Nitrene ,Phosphorus ,Organic Chemistry ,Posttranslational modification ,chemistry.chemical_element ,Surface modification ,Organic chemistry ,Chelation ,Bifunctional - Abstract
Synthesis and evaluation of a new class of photochemically activated heterobifunctional chelating agents for protein modification is described. Selective functionalization of perfluoroaryl azides by versatile phosphorus hydrazide ligating systems 2 and 3 for the complexation of transition metals and analogous radiometals form the basis for these new agents. The utility of the photogenerated precursors from these bifunctional agents to form covalent attachments is demonstrated through examination of C-H bond insertion on cyclohexane. Representative amide-coupled phosphorus hydrazides 5 and 6 provide78% insertion of the probe into unactivated C-H bonds of cyclohexane with short photolysis times. Photoconjugation of the photoactivable heterobifunctional chelating agent 6 and its Pd metalated analog 7 with HSA is also evaluated. The uncomplexed chelate appears to add to HSA with high efficiency, consistent with the observed 82% bond insertion into model solvents. Covalent attachment of 7, evaluated through the use of (109)Pd, was estimated to be between 49% and 74% with the uncertainty arising because of prephotolysis association of the (109)Pd complex with HSA. The application of in situ (19)F NMR to distinguish between bond insertion and noninsertion processes is demonstrated. These results suggest that functionalized perfluoroaryl azido phosphorus hydrazides may find utility as heterobifunctional photolabeling agents for attaching radionuclides to proteins and antibodies.
- Published
- 1997
18. Chemistry of Bifunctional Photoprobes
- Author
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Karl T. Weber, Przemyslaw Lusiak, Raghoottama S. Pandurangi, Robert R. Kuntz, and Yao Sun
- Subjects
biology ,Photoaffinity labeling ,Stereochemistry ,Organic Chemistry ,Lisinopril ,Angiotensin-converting enzyme ,Biological activity ,Biochemistry ,chemistry.chemical_compound ,chemistry ,Drug Discovery ,medicine ,biology.protein ,Potency ,Surface modification ,Chelation ,Bifunctional ,Molecular Biology ,circulatory and respiratory physiology ,medicine.drug - Abstract
The synthesis and biological activity of functionalized lisinopril, a potent angiotensin converting enzyme (ACE) inhibitor is described. Selective functionalization of lisinopril is achieved at the secondary amino position by a photochemical method, whereas esterfication of the carboxylic groups and modification at the primary amino group is achieved by chemical methods. Autoradiographic investigations using competitive 125 I radioactive binding assays with the modified lisinopril reveal that the terminal amino group modification enhanced the binding to ACE, whereas the secondary amino group functionalization did not differ significantly from the binding properties of native lisinopril. However, esterification of the carboxyl groups reduced the inhibitory potentency from n M to μ M . These results suggest that lisinopril can be derivatized with preservation of inhibition potency toward ACE. These modifications may find utility in the development of photoaffinity labeling agents for ACE or to incorporate bifunctional chelating agents carrying diagnostic radiometals for the development of cardiac imaging agents.
- Published
- 1997
19. Erratum: Constraining theSfactor ofN15(p,γ)O16at astrophysical energies [Phys. Rev. C82, 055804 (2010)]
- Author
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C. Rossi Alvarez, Gianluca Imbriani, Edward Stech, Oscar Straniero, F. Käppeler, P. J. LeBlanc, R. E. Azuma, C. Rolfs, S. Falahat, H. Leiste, Frank Strieder, Filippo Terrasi, Richard deBoer, Vincenzo Roca, A. Palumbo, Gy. Gyürky, C. Mazzocchi, R. Menegazzo, Paolo Prati, Antonio Caciolli, E. Somorjai, M. Marta, Q. Li, Zs. Fülöp, Manoel Couder, Carlo Broggini, S. O'Brien, Antonios Kontos, A. Best, Mary Beard, Wanpeng Tan, G. Gervino, M. Junker, H. P. Trautvetter, H. Costantini, E. Uberseder, A. Lemut, Joachim Görres, C. Gustavino, Z. Elekes, B. Limata, R. Kuntz, A. Formicola, P. Corvisiero, A. Guglielmetti, Daniel Bemmerer, and Michael Wiescher
- Subjects
Physics ,Nuclear reaction ,Nuclear and High Energy Physics ,Isotope ,010308 nuclear & particles physics ,Stable isotope ratio ,S-factor ,Gamma ray ,01 natural sciences ,Isotopes of oxygen ,Nuclear physics ,0103 physical sciences ,010303 astronomy & astrophysics ,Radioactive decay ,Oxygen-16 - Published
- 2011
20. Competitive photocatalytic reduction of H+ and C2H2 by Mo2S4(S2C2H4)2−2 on colloidal TiO2
- Author
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Lufei Lin and Robert R. Kuntz
- Subjects
chemistry.chemical_classification ,Ethylene ,Stereochemistry ,General Chemical Engineering ,General Physics and Astronomy ,Electron donor ,General Chemistry ,Photochemistry ,Catalysis ,chemistry.chemical_compound ,Electron transfer ,Light intensity ,Colloid ,Hydrocarbon ,chemistry ,Photocatalysis - Abstract
The competitive photocatalytic reduction of H + and C 2 H 2 at catalytic sites formed when Mo 2 S 4 (S 2 C 2 H 4 ) 2− 2 is photoreduced on colloidal TiO 2 in the presence of a sacrificial electron donor was studied. Comparisons of the total number of electrons transferred to both substrates as a function of pH suggest that the substrates compete for a common catalytic site. Based on analogies with homogeneous solution studies, a mechanism involving an Mo(IV) dimeric species as the catalytic site is suggested. The efficiency for conversion of incident light to reduced products increases with decreasing light intensity and maximizes at about seven electrons transferred per 100 photons absorbed.
- Published
- 1992
21. The photocatalytic production of H2 from molybdenum-sulfur compounds loaded on TiO2
- Author
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Shaeel Al-Thabaiti, Lufei Lin, and Robert R. Kuntz
- Subjects
Aqueous solution ,Hydrogen ,General Chemical Engineering ,Inorganic chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,Ethylenediamine ,General Chemistry ,Catalysis ,Light intensity ,chemistry.chemical_compound ,chemistry ,Molybdenum ,Photocatalysis ,Platinum - Abstract
The photocatalytic of molecular hydrogen from aqueous suspensions of colloidal TiO2 loaded with MoS2−4 and Mo2S4(S2C2H4)2−2 was studied as a function of pH, loading and light intensity. The efficiency of these systems, in which polyvinyl alcohol and ethylenediamine tetraacetic acid (EDTA) were utilized as sacrificial electron donors, was compared with the well-studied systems utilizing platinum as an electron transfer catalyst. Optimum loading levels were 20 ions per particle for tetrathiomolybdate and 6 ions per particle for the thio dimer. Both of the Mo-S systems were only about 40% as efficient as platinum. Quantum yields of molecular hydrogen approximately doubled as the intensity was decreased by a factor of 10 and increased about twofold when the more efficient hole scavenger, EDTA, was added to the mixture. The highest yield obtained, in terms of the percentage utilization of the photoproduced electrons, was 11.5% compared with 28.2% for platinum. Except for differences in optimum loading levels, both catalysts gave similar results.
- Published
- 1992
22. Valganciclovir for Suppression of Human Herpesvirus 8 Replication: A Randomized, Double-Blind, Placebo-Controlled, Crossover Trial
- Author
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Lawrence Corey, Shannon Hamilton, Anna Wald, Jie Wang, Steven R. Kuntz, Elizabeth M Krantz, Corey Casper, Stacy Selke, and Meei Li Huang
- Subjects
Adult ,Male ,Ganciclovir ,medicine.medical_specialty ,Oropharynx ,HIV Infections ,Biology ,Placebo ,Virus Replication ,Gastroenterology ,Antiviral Agents ,Article ,law.invention ,Double-Blind Method ,Randomized controlled trial ,law ,Internal medicine ,medicine ,Humans ,Immunology and Allergy ,Valganciclovir ,Viral shedding ,Sarcoma, Kaposi ,Aged ,Cross-Over Studies ,virus diseases ,Middle Aged ,Crossover study ,Virus Shedding ,Clinical trial ,Infectious Diseases ,Relative risk ,Immunology ,Herpesvirus 8, Human ,Patient Compliance ,medicine.drug - Abstract
BACKGROUND: Human herpesvirus-8 (HHV-8) replication is critical in the induction and maintenance of Kaposi sarcoma, primary effusion lymphoma, and some cases of Castleman disease. In vitro and observational studies suggest that ganciclovir inhibits HHV-8 replication, but no randomized clinical trials have been conducted. METHODS: A total of 26 men infected with HHV-8 were randomized to receive 8 weeks of valganciclovir administered orally (900 mg once per day) or 8 weeks of placebo administered orally. After a 2-week washout period, participants in each group received the study drug they had not yet taken (either valganciclovir or placebo), for 8 additional weeks. Oral swab samples were collected daily during the study, and HHV-8 and CMV DNA were quantified by real-time PCR. RESULTS: A total of 16 human immunodeficiency virus (HIV)-positive men and 10 HIV-negative men enrolled in and completed the study. Of the 3,439 swab samples that participants had been expected to provide, 3029 (88%) were available for analysis. HHV-8 was detected on 44% of swabs collected from participants who were receiving placebo, compared with 23% of swabs collected from participants who were receiving valganciclovir (relative risk [RR], 0.54 [95% confidence interval {CI}, 0.33-0.90]; P = .02). Valganciclovir reduced oropharyngeal shedding of cytomegalovirus by 80% (RR, 0.20 [95% CI, 0.08-0.48]; P < .001). Shedding of HHV-8 and shedding of cytomegalovirus were independent. Hematologic, renal, or hepatic toxicities were no more common among participants who received the active drug, compared with those who received placebo, though participants who received valganciclovir reported more days of diarrhea. CONCLUSIONS: Valganciclovir administered orally once per day is well tolerated and significantly reduces the frequency and quantity of HHV-8 replication.
- Published
- 2008
23. Evaluation of NEMO Communications Using Hybrid Measurement
- Author
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R. Kuntz and J. Lorchat
- Subjects
business.industry ,Computer science ,Embedded system ,Mobile computing ,The Internet ,Architecture ,business - Abstract
In this paper, we introduce a new apparatus to evaluate communications performance, which combines both active and passive measurements. This approach is very suited for moving networks (NEMO) in ITS environments, as we will show in a detailed scenario and experiment. The experiment uses the currently available NEPL implementation of NEMO based on the GNU/Linux operating system to demonstrate the actual feasibility of the scenario. Then the hybrid measurements approach makes it possible for us to thoroughly analyze the outcomes, be they achievements or failures, of this very architecture.
- Published
- 2006
24. Arch widths in adults with Class I crowded and Class III malocclusions compared with normal occlusions
- Author
-
Harold F. Bigelow, Timothy R. Kuntz, Frank J. Kohout, Charles R. Kremenak, Jane R. Jakobsen, and Robert N. Staley
- Subjects
Adult ,Male ,Class (set theory) ,genetic structures ,Adolescent ,Cephalometry ,Dentistry ,Orthodontics ,Arch width ,Class iii ,Malocclusion, Angle Class I ,Mandible ,Dental Arch ,Maxilla ,Humans ,Arch ,Maxillofacial Development ,Mathematics ,Analysis of Variance ,Sex Characteristics ,business.industry ,Malocclusion, Angle Class III ,cardiovascular system ,lipids (amino acids, peptides, and proteins) ,Female ,business - Abstract
To test the hypothesis that there is no difference between adults with Class I crowded (CICR), Class III (CIII), and Class I normal (CIN) occlusions with respect to (1) arch widths, (2) width of the maxillary and mandibular arches, (3) gender dimorphism within groups, and (4) gender comparisons.Samples of 39 CICR subjects, 40 CIII subjects, and 40 CIN subjects were studied. All subjects were white Americans with no history of orthodontic treatment. An analysis of variance and Duncan's test statistically compared the groups and genders.The CICR group had mean maxillary and mandibular intermolar and alveolar arch widths significantly smaller than the CIN group. The CIII group had mean maxillary intermolar and alveolar arch widths significantly smaller than the CIN group. Mean maxillary and mandibular intercanine arch widths were similar in the three groups. The CICR and CIN groups had similar mean maxillary/mandibular intermolar and alveolar differences significantly larger than the negative differences observed in the CIII group. Gender dimorphisms were identical in the CIII and CIN groups. The CICR group differed by not having a gender dimorphism in the maxillary alveolar width and having a gender dimorphism in the mandibular intercanine width. Gender comparisons between groups were similar in intercanine widths but differed in other widths.The hypothesis was rejected by the findings of this study.
- Published
- 2005
25. Chemistry of bifunctional photoprobes. 6. Synthesis and characterization of high specific activity metalated photochemical probes: development of novel rhenium photoconjugates of human serum albumin and fab fragments
- Author
-
Raghavan Rajagopalan, Raghoottama S. Pandurangi, Wynn A. Volkert, Uday Sharma, and Robert R. Kuntz
- Subjects
Magnetic Resonance Spectroscopy ,Time Factors ,Stereochemistry ,Photochemistry ,Serum albumin ,chemistry.chemical_element ,Ligands ,Chemical synthesis ,Catalysis ,chemistry.chemical_compound ,Immunoglobulin Fab Fragments ,medicine ,Organometallic Compounds ,Humans ,Chelation ,Tissue Distribution ,Bifunctional ,Immunoglobulin Fragments ,Serum Albumin ,Chelating Agents ,Radioisotopes ,Photolysis ,biology ,Molecular Structure ,Aryl ,Organic Chemistry ,Organotechnetium Compounds ,Rhenium ,Human serum albumin ,chemistry ,biology.protein ,Azide ,medicine.drug - Abstract
Functionalization of perfluoro aryl azides by bifunctional chelating agents (BFCAs) capable of forming high specific activity complexes with (99m)Tc (for gamma-imaging) and (188)Re (for radiotherapy) is described. The synthesis of multidonor BFCAs containing N(2)S(2), N(4), and N(3)S donor groups containing imidazole, pyridine, and pyrazine functionalities that may be important for tuning the pharmacokinetic parameters is also described. Functionalization of perfluoro aryl azides at various sites on BFCAs yields novel bifunctional photolabile chelating agents (BFPCAs) that are useful for covalent attachment to biomolecules. A representative Re-BFPCA 8a in a model solvent, diethylamine, proceeded to give a high yield of intermolecular NH insertion product without the decomplexation of the metal ion from 8a. All products originated from the photolysis of 8a in diethylamine are characterized by analytical techniques, and a plausible mechanism of formation of different photolytic products is suggested. The high yield of intermolecular NH insertion of Re-BFPCA 8a is extended to labeling of human serum albumin (HSA) and Fab fragments under aqueous conditions. The photolabeling technology developed here offers a new way to attach diagnostically and therapeutically useful radiotracers (e.g., (99m)Tc, (188)Re) to Fab fragments for potential noninvasive imaging and therapy of cancer.
- Published
- 2002
26. Production of radiolabeled monoclonal antibody conjugates by photoaffinity labeling
- Author
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Wynn A. Volkert, E.P. Mitchell, Alan R. Ketring, T.L. Feldbush, Richard A. Holmes, and Robert R. Kuntz
- Subjects
chemistry.chemical_compound ,Photoaffinity labeling ,Covalent bond ,Chemistry ,Stereochemistry ,Ligand ,Acridine ,Organic chemistry ,Production (computer science) ,Reaction intermediate ,Photoaffinity Labels ,Bifunctional - Abstract
This report discusses activities and progress that has occurred since initiation of this project on September 1, 1989. We have synthesized ethyl N,N{prime}-bis(benzoylmercaptoacetyl)-2,3-diaminopropanoate, a ligand to be used as a bifunctional chelating agent (BFCA), to form {sup 186}Re or {sup 188}Re ({sup 186}Re/{sup 188}Re) complexes. {sup 186}Re/{sup 188}Re, in reducing media, reacts with this ligand to form {sup 186}Re/{sup 188}Re-CO{sub 2}DADS chelates that will be used to formulate new radiolabeled photoaffinity labels (RPALs). Initial steps have been taken to synthesize R-As-dithiol compounds. This approach will be used to produce {sup 77}As-RPALs or covalently link {sup 77}As directly to monoclonal antibodies (MAbs). The R group will contain a group that can be used for conjugation reactions. Spectral and photochemical properties of various types of photoaffinity labels (PALs) have been studied. Acrylo-azido compounds and 9-azido acridine have been studied as well as several other photoprobes. The binding characteristics of the azido-based PALs to HSA have been studied and progress has been made on developing techniques for efficiently separating of non-covalently sound PALs. The Nd-YAG laser was purchased and arrived in 1990. It has been assembled and tested and is now operational.
- Published
- 1990
27. Photocatalytic reduction of acetylene by [MoOCl(dppe)2]+Cl− on TiO2
- Author
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R. Kuntz, Robert, primary
- Published
- 1994
- Full Text
- View/download PDF
28. Nouveaux organes de réglage et de sécurité sur les circuits industriels
- Author
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R. Kuntz and G. Combes
- Subjects
Water Science and Technology - Published
- 1980
29. Effects of the Large June 1975 Meteoroid Storm on Earth's Ionosphere
- Author
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V. L. R. Kuntz, Pierre Kaufmann, L. R. Piazza, J. W. S. Vilas Boas, N. M. Paes Leme, K. Brecher, and J. Crouchley
- Subjects
Daytime ,Multidisciplinary ,Meteoroid ,Environmental science ,Storm ,Sunset ,Very low frequency ,Ionosphere ,Atmospheric sciences ,Southern Hemisphere ,Radio wave - Abstract
The June 1975 meteoroid storm detected on the moon by the Apollo seismometers was the largest ever observed. Reexamination of radio data taken at that time showed that the storm also produced pronounced disturbances on Earth, which were recorded as unique phase anomalies on very low frequency (VLF) radio propagation paths in the low terrestrial ionosphere. Persistent effects were observed for the major storm period (20 to 30 June 1975), including reductions in the diurnal phase variation, advances in the nighttime and daytime phase levels, and reductions in the sunset phase delay rate. Large nighttime phase advances, lasting a few hours, were detected on some days at all VLF transmissions, and for the shorter propagation path they were comparable to solar Lyman alpha daytime ionization. Ion production rates attributable to the meteor storm were estimated to be about 0.6 to 3.0 ions per centimeter cubed per second at the E and D regions, respectively. The storm was a sporadic one with a radiant (that is, the point of apparent origin in the sky) located in the Southern Hemisphere, with a right ascension 1 to 2 hours larger than the sun's right ascension.
- Published
- 1989
30. Flash photolysis of human serum albumin: characterization of the indole triplet absorption spectrum and decay at ambient temperature
- Author
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Wynn A. Volkert, Robert R. Kuntz, B. Hicks, M. White, and Camillo A. Ghiron
- Subjects
Indole test ,Quantitative Biology::Biomolecules ,Multidisciplinary ,Indoles ,Photolysis ,Absorption spectroscopy ,biology ,Chemistry ,Spectrum Analysis ,Tryptophan ,Human serum albumin ,Photochemistry ,Kinetics ,medicine ,biology.protein ,Flash photolysis ,Humans ,Singlet state ,Bovine serum albumin ,Phosphorescence ,Serum Albumin ,medicine.drug ,Research Article - Abstract
The method of flash photolysis was used to identify the transient absorption spectrum and to characterize the decay kinetics of the indole triplet of human serum albumin. This protein was studied because it contains a single indole side chain which is deeply buried in an expandable oily region and because the phosphorescence of the homologous indole in bovine serum albumin could not be detected at ambient temperatures. The transient was identified on the following basis: (i) its triplet-triplet absorption spectrum was similar to those previously reported for indole and tryptophan; (ii) it was quenched by small quantities of oxygen; and (iii) it was photobleached by 370- to 700-nm light. In a nitrogen-saturated solution at room temperature, the indole triplet decays exponentially for more than a factor of 10 with a lifetime of 0.5 msec. These observations suggest that, because of its exponential decay and relatively long lifetime, the triplet will be more valuable than the indole singlet as an intrinsic reporter group for the study of the structure and dynamics of proteins in solution.
- Published
- 1978
31. Letter: The reactions of hydrogens atoms in aqueous solutions: effect of pH on reactions with cysteine and penicillamine
- Author
-
J T, Wu and R R, Kuntz
- Subjects
Solutions ,Radiation-Sensitizing Agents ,Penicillamine ,Water ,Radiation-Protective Agents ,Cysteine ,Hydrogen-Ion Concentration ,Hydrogen - Published
- 1975
32. The reactions of hydrogen atoms in aqueous solutions: thiols
- Author
-
T L, Tung and R R, Kuntz
- Subjects
Radiochemistry ,Cysteamine ,Penicillamine ,Radiation-Protective Agents ,Cysteine ,Sulfhydryl Compounds ,Propionates ,Hydrogen ,Mercaptoethanol - Published
- 1973
33. Hydrated electron reactions with thiols in acidic aqueous solutions
- Author
-
T L, Tung and R R, Kuntz
- Subjects
Radiation Effects ,Solutions ,Cysteamine ,Penicillamine ,Water ,Cysteine ,Sulfhydryl Compounds ,Hydrogen-Ion Concentration - Published
- 1973
34. The Reactions of Hydrogen Atoms in Aqueous Solutions: Effect of pH on Reactions with Cysteine and Penicillamine
- Author
-
Jiunn-tsair Wu and Robert R. Kuntz
- Subjects
chemistry.chemical_classification ,Radiation ,Aqueous solution ,Hydrogen ,Chemistry ,Penicillamine ,Inorganic chemistry ,Biophysics ,chemistry.chemical_element ,Dissociation (chemistry) ,Amino acid ,Reaction rate constant ,medicine ,Radiology, Nuclear Medicine and imaging ,medicine.drug ,Cysteine - Abstract
The total rate constant for H-atom reactions with cysteine and penicillamine has been determined at pH 1 and pH 6 utilizing a photolytic source of H-atoms. The effect of COOH dissociation is to increase k/sub cysteine/ by 1.3 and k/sub penicillamine/ by 1.75. This effect is of the same magnitude as that observed for nonsulfhydryl amino acids. At higher pH values, dissociation of NH$sub 3$$sup +$ causes further enhancement of the rate for penicillamine. The mechanism of H-atom reactions with these amino acids appears to be independent of pH in the range of 1 to 6. (auth)
- Published
- 1975
35. The Reactions of Hydrogen Atoms in Aqueous Solutions: Thiols
- Author
-
Robert R. Kuntz and Tzu-Lin Tung
- Subjects
Sh groups ,Radiation ,Aqueous solution ,Hydrogen ,Chemistry ,Inorganic chemistry ,Biophysics ,chemistry.chemical_element ,Hydrogen atom ,Radiation chemistry ,Medicinal chemistry ,Reaction rate constant ,Radiolysis ,Molecule ,Radiology, Nuclear Medicine and imaging - Abstract
k4 ks two mechanisms: (a) H + RSH- Hs + RS, and b) H + RSH H2S + R. The rate constant for reaction 4 is influenced by the presence of functional groups within the molecule. It is also found that reaction 4 is the predominant mechanism for hydrogen atom reaction with primary sulfhydryl compounds while reaction 5 is most important for secondary and tertiary SH groups. The relationship of these results to observed
- Published
- 1973
36. Hydrated Electron Reactions with Thiols in Acidic Aqueous Solutions
- Author
-
Tzu-Lin Tung and Robert R. Kuntz
- Subjects
Radiation ,Aqueous solution ,Inorganic chemistry ,Biophysics ,Protonation ,Solvated electron ,Chemical reaction ,Dissociation (chemistry) ,chemistry.chemical_compound ,Reaction rate constant ,chemistry ,Ionic strength ,Zwitterion ,Radiology, Nuclear Medicine and imaging - Abstract
The rates of hydrated electron reactions with cysteamine, cysteine, thioglycol, α-mercaptopropionic acid, β-mercaptopropionic acid, and penicillamine have been studied in the pH 1-3 region. Hydrogen yields, which are a function of pH in this region, were used to monitor the competition between H+ and RSH for hydrated electrons. Corrections were applied to the observed rate constants to account for dissociation of the COOH group and the ionic strength effect on hydrated electron reactions. In the cases of cysteine and penicillamine, the rate constants for reaction with protonated amino acids at infinite dilution were greater by a factor of 3-5 than those for reaction with the zwitterion. Uncharged species show no pH dependence of the rate constant within this region. All rate constants measured were of comparable magnitude and approached the diffusion controlled limit.
- Published
- 1973
37. Photocatalytic reduction of acetylene by [MoOCl(dppe) 2] +Cl − on TiO 2
- Author
-
R. Kuntz, Robert
- Published
- 1994
- Full Text
- View/download PDF
38. Health Product Manufacturers and Innovators COVID-19 Impact Assessment: Lessons Learned and Compelling Needs.
- Author
-
Mammen M, Narasimhan V, Kuntz R, Lewis-Hall F, Poul M, and Schechter A
- Abstract
Competing Interests: Conflict-of-Interest Disclosures: Dr. Lewis-Hall discloses that she is a member of the board of directors for SpringWorks Therapeutics, Exact Sciences, and 1Life Healthcare; she is a consultant for PhRMA; and she is an advisor to SAAMA Technologies, Topography Health, and Catalio. Dr. Mammen discloses that his employer received funding from the US government to develop a COVID-19 vaccine; that his employer collaborated with BCG; that his employer’s COVID-19 vaccine has received emergency use authorization in the US, European Union, and other countries; and that Johnson & Johnson is a multi-faceted company that has pharmaceutical, consumer, and medical devices businesses. Dr. Narasimhan discloses that his employer is currently undertaking an internal drug discovery program toward a pan-Coronavirus Mpro inhibitor; that his employer has an option and license agreement to develop, manufacture and commercialize two Molecular Partners’ anti-COVID-19 DARPin® candidates; and that his employer has initial agreements with Pfizer-BioNTech and CureVac to manufacture their COVID-19 vaccines, and with Roche for the production of the API for Actemra/RoActemra®. Mr. Schechter discloses that his employer has performed COVID-19 diagnostic and antibody testing, supported COVID-19 clinical trials and study opportunities of potential treatments and vaccines with external sponsors, and worked with the U.S. Centers for Disease Control and Prevention to provide sequencing of samples of SARS-CoV-2 and that for these laboratory testing and drug development services, his employer has received reimbursement from various sources, including governmental agencies; and that in preparing the submitted work, Labcorp consulted with the American Clinical Laboratory Association, the national trade association representing leading clinical laboratories.
- Published
- 2022
- Full Text
- View/download PDF
39. Attribution of Adverse Events Following Coronary Stent Placement Identified Using Administrative Claims Data.
- Author
-
Dhruva SS, Parzynski CS, Gamble GM, Curtis JP, Desai NR, Yeh RW, Masoudi FA, Kuntz R, Shaw RE, Marinac-Dabic D, Sedrakyan A, Normand ST, Krumholz HM, and Ross JS
- Subjects
- Aged, Aged, 80 and over, Coronary Restenosis mortality, Coronary Restenosis therapy, Coronary Thrombosis mortality, Coronary Thrombosis therapy, Databases, Factual, Female, Humans, Male, Myocardial Infarction mortality, Myocardial Infarction therapy, Percutaneous Coronary Intervention mortality, Product Surveillance, Postmarketing, Registries, Retreatment, Risk Assessment, Risk Factors, Time Factors, Treatment Outcome, United States epidemiology, Administrative Claims, Healthcare, Drug-Eluting Stents, Medicare, Percutaneous Coronary Intervention adverse effects, Percutaneous Coronary Intervention instrumentation
- Abstract
Background More than 600 000 coronary stents are implanted during percutaneous coronary interventions (PCIs) annually in the United States. Because no real-world surveillance system exists to monitor their long-term safety, claims data are often used for this purpose. The extent to which adverse events identified with claims data can be reasonably attributed to a specific medical device is uncertain. Methods and Results We used deterministic matching to link the NCDR (National Cardiovascular Data Registry) CathPCI Registry to Medicare fee-for-service claims for patients aged ≥65 years who underwent PCI with drug-eluting stents (DESs) between July 1, 2009 and December 31, 2013. We identified subsequent PCIs within 1 year of the index procedure in Medicare claims as potential safety events. We linked these subsequent PCIs back to the NCDR CathPCI Registry to ascertain how often the revascularization could be reasonably attributed to the same coronary artery as the index PCI (ie, target vessel revascularization). Of 415 306 DES placements in 368 194 patients, 33 174 repeat PCIs were identified in Medicare claims within 1 year. Of these, 28 632 (86.3%) could be linked back to the NCDR CathPCI Registry; 16 942 (51.1% of repeat PCIs) were target vessel revascularizations. Of these, 8544 (50.4%) were within a previously placed DES: 7652 for in-stent restenosis and 1341 for stent thrombosis. Of 16 176 patients with a claim for acute myocardial infarction in the follow-up period, 4446 (27.5%) were attributed to the same coronary artery in which the DES was implanted during the index PCI (ie, target vessel myocardial infarction). Of 24 288 patients whose death was identified in claims data, 278 (1.1%) were attributed to the same coronary artery in which the DES was implanted during the index PCI. Conclusions Most repeat PCIs following DES stent implantation identified in longitudinal claims data could be linked to real-world registry data, but only half could be reasonably attributed to the same coronary artery as the index procedure. Attribution among those with acute myocardial infarction or who died was even less frequent. Safety signals identified using claims data alone will require more in-depth examination to accurately assess stent safety.
- Published
- 2020
- Full Text
- View/download PDF
40. Overview and experience of the YODA Project with clinical trial data sharing after 5 years.
- Author
-
Ross JS, Waldstreicher J, Bamford S, Berlin JA, Childers K, Desai NR, Gamble G, Gross CP, Kuntz R, Lehman R, Lins P, Morris SA, Ritchie JD, and Krumholz HM
- Subjects
- Humans, Clinical Trials as Topic, Information Dissemination methods
- Abstract
The Yale University Open Data Access (YODA) Project has facilitated access to clinical trial data since 2013. The purpose of this article is to provide an overview of the Project, describe key decisions that were made when establishing data sharing policies, and suggest how our experience and the experiences of our first two data generator partners, Medtronic, Inc. and Johnson & Johnson, can be used to enhance other ongoing or future initiatives.
- Published
- 2018
- Full Text
- View/download PDF
41. Can machine learning complement traditional medical device surveillance? A case study of dual-chamber implantable cardioverter-defibrillators.
- Author
-
Ross JS, Bates J, Parzynski CS, Akar JG, Curtis JP, Desai NR, Freeman JV, Gamble GM, Kuntz R, Li SX, Marinac-Dabic D, Masoudi FA, Normand ST, Ranasinghe I, Shaw RE, and Krumholz HM
- Abstract
Background: Machine learning methods may complement traditional analytic methods for medical device surveillance., Methods and Results: Using data from the National Cardiovascular Data Registry for implantable cardioverter-defibrillators (ICDs) linked to Medicare administrative claims for longitudinal follow-up, we applied three statistical approaches to safety-signal detection for commonly used dual-chamber ICDs that used two propensity score (PS) models: one specified by subject-matter experts (PS-SME), and the other one by machine learning-based selection (PS-ML). The first approach used PS-SME and cumulative incidence (time-to-event), the second approach used PS-SME and cumulative risk (Data Extraction and Longitudinal Trend Analysis [DELTA]), and the third approach used PS-ML and cumulative risk (embedded feature selection). Safety-signal surveillance was conducted for eleven dual-chamber ICD models implanted at least 2,000 times over 3 years. Between 2006 and 2010, there were 71,948 Medicare fee-for-service beneficiaries who received dual-chamber ICDs. Cumulative device-specific unadjusted 3-year event rates varied for three surveyed safety signals: death from any cause, 12.8%-20.9%; nonfatal ICD-related adverse events, 19.3%-26.3%; and death from any cause or nonfatal ICD-related adverse event, 27.1%-37.6%. Agreement among safety signals detected/not detected between the time-to-event and DELTA approaches was 90.9% (360 of 396, k =0.068), between the time-to-event and embedded feature-selection approaches was 91.7% (363 of 396, k =-0.028), and between the DELTA and embedded feature selection approaches was 88.1% (349 of 396, k =-0.042)., Conclusion: Three statistical approaches, including one machine learning method, identified important safety signals, but without exact agreement. Ensemble methods may be needed to detect all safety signals for further evaluation during medical device surveillance., Competing Interests: Disclosure JSR receives support from the US FDA as part of the Centers for Excellence in Regulatory Science and Innovation program and from the Laura and John Arnold Foundation to support the Collaboration on Research Integrity and Transparency at Yale. JSR, NRD, HMK, and GMG receive research support through Yale University from Johnson and Johnson to develop methods of clinical trial data sharing. JSR and GMG receive research support from the Blue Cross Blue Shield Association to better understand medical technology evidence generation. JSR, JPC, NRD, SXL, SLTM, IR, HMK, and CSP work under contract to the Centers for Medicare and Medicaid Services to develop and maintain performance measures that are used for public reporting. JVF receives salary support from the American College of Cardiology NCDR, and modest consulting fees from Janssen Pharmaceuticals. RK is an employee of Medtronic Inc. DMD is an employee of the FDA. HMK chairs a cardiac scientific advisory board for United Health, is a participant/participant representative of the IBM Watson Health Life Sciences Board, is a member of the Advisory Board for Element Science and the Physician Advisory Board for Aetna, and is the founder of Hugo, a personal health-information platform. The authors report no other conflicts of interest in this work.
- Published
- 2017
- Full Text
- View/download PDF
42. Dorsal root ganglia neurite outgrowth measured as a function of changes in microelectrode array resistance.
- Author
-
Renna JM, Stukel JM, Kuntz Willits R, and Engeberg ED
- Subjects
- Animals, Cell Culture Techniques methods, Cells, Cultured, Chick Embryo, Electric Impedance, Ganglia, Spinal embryology, Microelectrodes, Neuronal Outgrowth, Cell Culture Techniques instrumentation, Ganglia, Spinal cytology, Neurites physiology
- Abstract
Current research in prosthetic device design aims to mimic natural movements using a feedback system that connects to the patient's own nerves to control the device. The first step in using neurons to control motion is to make and maintain contact between neurons and the feedback sensors. Therefore, the goal of this project was to determine if changes in electrode resistance could be detected when a neuron extended a neurite to contact a sensor. Dorsal root ganglia (DRG) were harvested from chick embryos and cultured on a collagen-coated carbon nanotube microelectrode array for two days. The DRG were seeded along one side of the array so the processes extended across the array, contacting about half of the electrodes. Electrode resistance was measured both prior to culture and after the two day culture period. Phase contrast images of the microelectrode array were taken after two days to visually determine which electrodes were in contact with one or more DRG neurite or tissue. Electrodes in contact with DRG neurites had an average change in resistance of 0.15 MΩ compared with the electrodes without DRG neurites. Using this method, we determined that resistance values can be used as a criterion for identifying electrodes in contact with a DRG neurite. These data are the foundation for future development of an autonomous feedback resistance measurement system to continuously monitor DRG neurite outgrowth at specific spatial locations.
- Published
- 2017
- Full Text
- View/download PDF
43. Modular scaffolds assembled around living cells using poly(ethylene glycol) microspheres with macroporation via a non-cytotoxic porogen.
- Author
-
Scott EA, Nichols MD, Kuntz-Willits R, and Elbert DL
- Subjects
- Hot Temperature, Humans, Light, Lysophospholipids administration & dosage, Neovascularization, Physiologic, Polymers chemistry, Scattering, Radiation, Sphingosine administration & dosage, Sphingosine analogs & derivatives, Sulfates chemistry, Surface-Active Agents chemistry, Temperature, Time Factors, Biocompatible Materials chemistry, Hydrogels chemistry, Microspheres, Polyethylene Glycols chemistry
- Abstract
Modular, bioactive, macroporous scaffolds were formed by crosslinking poly(ethylene glycol) (PEG) microspheres around living cells. Hydrogel microspheres were produced from reactive PEG derivatives in aqueous sodium sulfate solutions without the use of surfactants or copolymers. Microspheres were formed following thermally induced phase separation if the gel point was reached prior to extensive coarsening of the PEG-rich domains. Three types of PEG microspheres with different functionalities were used to form scaffolds: one type provided mechanical support, the second type provided controlled delivery of the angiogenesis-promoting molecule, sphingosine 1-phosphate (S1P) and the third type served as a slowly dissolving non-cytotoxic porogen. Scaffolds were formed by centrifuging microspheres in the presence of HepG2 hepatoma cells, resulting in a homogenous distribution of cells. During overnight incubation at 37 degrees C, the microspheres reacted with serum proteins in cell culture medium to stabilize the scaffolds. Within 2 days in culture, macropores formed due to the dissolution of the porogenic PEG microspheres, without affecting cell viability. Gradients in porosity were produced by varying the buoyancy of the porogenic microspheres. Conjugated RGD cell adhesion peptides and the delivery of S1P promoted endothelial cell infiltration through macropores in the scaffolds. The scaffolds presented here differ from previous hydrogel scaffolds in that: (i) cells are not encapsulated in hydrogel; (ii) macropores form in the presence of cells; and (iii) scaffold properties are controlled by the modular assembly of different microspheres that perform distinct functions.
- Published
- 2010
- Full Text
- View/download PDF
44. Seasonal adjustment of energy budget in a large wild mammal, the Przewalski horse (Equus ferus przewalskii) I. Energy intake.
- Author
-
Kuntz R, Kubalek C, Ruf T, Tataruch F, and Arnold W
- Subjects
- Animals, Diet, Dietary Fiber administration & dosage, Digestion, Female, Male, Nutritional Status, Animals, Wild physiology, Energy Intake, Energy Metabolism, Horses physiology, Seasons
- Abstract
Large ruminants respond to changing plant phenology during winter by decreasing voluntary food intake, increasing gut passage time and utilizing body fat reserves. It is uncertain, however, how other large mammals with a non-ruminant digestive physiology cope with winter forage conditions. Therefore, we investigated seasonality of energy intake in a large herbivorous wild mammal, the Przewalski horse (Equus ferus przewalskii). Throughout all seasons we used the n-alkane method to measure daily dry matter intake (DMI), diet composition and digestion, and determined an index of gut passage time in horses living under close to natural conditions. DMI correlated positively with its content of crude protein and nitrogen-free extract. Independent of these effects, DMI further varied seasonally with a peak in autumn and a nadir in late winter. Fluctuations of DMI corresponded to the annual change in body condition, which decreased during winter while energy reserves were depleted, and increased during the fattening period. Gut passage time varied in the course of the year and was longer during winter when the diet was high in crude fibre. Nevertheless, changes in gut passage time occurred rather independently of changes in forage composition and DMI, suggesting endogenous control for timely adaption of the digestive strategy to meet predictable changes in forage quality.
- Published
- 2006
- Full Text
- View/download PDF
45. Seasonal adjustment of energy budget in a large wild mammal, the Przewalski horse (Equus ferus przewalskii) II. Energy expenditure.
- Author
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Arnold W, Ruf T, and Kuntz R
- Subjects
- Animals, Body Temperature, Body Temperature Regulation, Eating, Female, Heart Rate, Male, Motor Activity, Pregnancy, Reproduction, Animals, Wild physiology, Energy Metabolism, Horses physiology, Seasons
- Abstract
Many large mammals show pronounced seasonal fluctuations of metabolic rate (MR). It has been argued, based on studies in ruminants, that this variation merely results from different levels of locomotor activity (LA), and heat increment of feeding (HI). However, a recent study in red deer (Cervus elaphus) identified a previously unknown mechanism in ungulates--nocturnal hypometabolism--that contributed significantly to reduced energy expenditure, mainly during late winter. The relative contribution of these different mechanisms to seasonal adjustments of MR is still unknown, however. Therefore, in the study presented here we quantified for the first time the independent contribution of thermoregulation, LA and HI to heart rate (f(H)) as a measure of MR in a free-roaming large ungulate, the Przewalski horse or Takhi (Equus ferus przewalskii Poljakow). f(H) varied periodically throughout the year with a twofold increase from a mean of 44 beats min(-1) during December and January to a spring peak of 89 beats min(-1) at the beginning of May. LA increased from 23% per day during December and January to a mean level of 53% per day during May, and declined again thereafter. Daily mean subcutaneous body temperature (T(s)) declined continuously during winter and reached a nadir at the beginning of April (annual range was 5.8 degrees C), well after the annual low of air temperature and LA. Lower T(s) during winter contributed considerably to the reduction in f(H). In addition to thermoregulation, f(H) was affected by reproduction, LA, HI and unexplained seasonal variation, presumably reflecting to some degree changes in organ mass. The observed phase relations of seasonal changes indicate that energy expenditure was not a consequence of energy uptake but is under endogenous control, preparing the organism well in advance of seasonal energetic demands.
- Published
- 2006
- Full Text
- View/download PDF
46. Treatment of saphenous vein bypass grafts with ultrasound thrombolysis: a randomized study (ATLAS).
- Author
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Singh M, Rosenschein U, Ho KK, Berger PB, Kuntz R, and Holmes DR Jr
- Subjects
- Abciximab, Adult, Aged, Angioplasty, Balloon, Coronary, Antibodies, Monoclonal therapeutic use, Combined Modality Therapy, Coronary Angiography, Coronary Disease diagnosis, Coronary Disease surgery, Female, Follow-Up Studies, Humans, Immunoglobulin Fab Fragments therapeutic use, Male, Middle Aged, Myocardial Infarction epidemiology, Stents, Syndrome, Treatment Outcome, Coronary Artery Bypass, Coronary Disease therapy, Saphenous Vein transplantation, Thrombosis therapy, Ultrasonic Therapy
- Abstract
Background: Percutaneous coronary interventions (PCIs) in saphenous vein grafts (SVGs) with thrombus have a high frequency of distal embolization. Acolysis (therapeutic ultrasound) can break up thrombus in vitro in animal models and humans. Whether this is beneficial during percutaneous SVG interventions is unknown., Methods and Results: We performed a trial of coronary ultrasound thrombolysis in which patients with an acute coronary syndrome undergoing PCI in SVGs were randomly assigned to receive acolysis or abciximab. The primary end point was a successful procedure, defined as final luminal diameter stenosis 30% or less with Thrombolysis In Myocardial Infarction grade 3 flow and freedom from major adverse cardiac events (composite of death, Q-wave, and non-Q-wave myocardial infarction [MI], emergency bypass procedure, disabling stroke, and target lesion revascularization). Of 181 enrolled, 92 received acolysis and 89 abciximab. Angiographic procedural success was achieved in 63% of acolysis patients and 82% of abciximab patients (P=0.008). Incidence of major adverse cardiac events at 30 days was 25% with acolysis and 12% with abciximab (P=0.036), attributable mainly to a greater frequency of non-Q-wave MI with acolysis (19.6% versus 7.9%, P=0.03). The incidence of Q-wave MI was also higher with acolysis (5.4% versus 2.2%, P=nonsignificant). The primary end point was achieved in 53.8% of acolysis patients and 73.1% of abciximab patients (P=0.014)., Conclusions: Use of therapeutic ultrasound in vein graft lesions in patients with acute coronary syndrome had poor angiographic outcome and increased the incidence of acute ischemic complications.
- Published
- 2003
- Full Text
- View/download PDF
47. A cerebellar-like terminal and postural tremor induced in normal man by transcranial magnetic stimulation.
- Author
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Topka H, Mescheriakov S, Boose A, Kuntz R, Hertrich I, Seydel L, Dichgans J, and Rothwell J
- Subjects
- Adult, Biomechanical Phenomena, Electric Stimulation, Electromyography, Evoked Potentials, Motor, Forearm innervation, Humans, Leg innervation, Male, Middle Aged, Parietal Lobe physiology, Parietal Lobe physiopathology, Posture, Reference Values, Somatosensory Cortex physiology, Somatosensory Cortex physiopathology, Wrist Joint, Cerebellar Ataxia physiopathology, Cerebellum physiology, Cerebellum physiopathology, Motor Activity, Multiple Sclerosis physiopathology, Transcranial Magnetic Stimulation, Tremor physiopathology
- Abstract
Trains of repetitive transcranial magnetic stimulation (TMS) at 10-30 Hz and intensities of 90-120% motor threshold were delivered through a figure of eight coil over the motor cortex while normal subjects made either rapid, self-terminated (ballistic) wrist movements or maintained the position of their wrist at a fixed angle. Movement kinematics and EMG activity in antagonistic forearm muscles were analysed. In the ballistic task, repetitive TMS had little effect on the velocity or acceleration of the initial segment of the movement, although it induced large terminal oscillations (tremor) around the target position at frequencies between 4.4 and 7.2 Hz. The likelihood that tremor would occur increased with increasing stimulus intensities or frequencies. It was maximal with stimulation over the forearm area, and decreased with stimulation over the leg area, or over parietal sites; there was no tremor during stimulation of cervical nerve roots. The frequency of the induced tremor was independent of the rate of stimulation and did not depend on the presence of excitatory and inhibitory motor responses to the stimulus. Stimulation could also induce tremor of the same frequency in the fixed task, but only during co-contraction of forearm muscles. The amplitude of tremor was proportional to the level of co-contraction. Clinically, the tremor induced by repetitive TMS appeared very similar to cerebellar tremors. In order to confirm this we investigated two cerebellar patients, one with autosomal dominant cerebellar ataxia and the other with multiple sclerosis. Both of them had a terminal tremor of 6-7 Hz in the wrist movement task. In the holding task, the amplitude of their postural tremor increased with the level of co-contraction in forearm muscles. Since the frequency of repetitive TMS-induced tremor was independent of stimulus parameters, we conclude that it represents some intrinsic property of the CNS. We suggest that the tremor is caused by disruption of cortical processes involved in terminating a voluntary movement or maintaining a posture. Similarities to cerebellar patients suggest that repetitive TMS may cause tremor by interfering with adaptive cerebellar afferent inflow to motor cortex. Repetitive TMS-induced tremor, therefore, may represent a model of some forms of cerebellar tremor in man.
- Published
- 1999
- Full Text
- View/download PDF
48. Carotid stenting and angioplasty: a statement for healthcare professionals from the Councils on Cardiovascular Radiology, Stroke, Cardio-Thoracic and Vascular Surgery, Epidemiology, and Prevention, and Clinical Cardiology, American Heart Association.
- Author
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Bettmann MA, Katzen BT, Whisnant J, Brant-Zawadzki M, Broderick JP, Furlan AJ, Hershey LA, Howard V, Kuntz R, Loftus CM, Pearce W, Roberts A, and Roubin G
- Subjects
- Endarterectomy, Carotid, Humans, Randomized Controlled Trials as Topic, Angioplasty, Balloon adverse effects, Carotid Stenosis therapy, Stents adverse effects
- Published
- 1998
- Full Text
- View/download PDF
49. Regarding "Statement regarding carotid angioplasty and stenting".
- Author
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Hobson RW 2nd, Brott T, Ferguson R, Roubin G, Moore W, Kuntz R, Howard G, and Ferguson J
- Subjects
- Endarterectomy, Carotid, Humans, Randomized Controlled Trials as Topic, Research Design, Societies, Medical, Angioplasty, Balloon, Carotid Artery Diseases therapy, Stents
- Published
- 1997
- Full Text
- View/download PDF
50. Retroperitoneal hematoma after cardiac catheterization: prevalence, risk factors, and optimal management.
- Author
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Kent KC, Moscucci M, Mansour KA, DiMattia S, Gallagher S, Kuntz R, and Skillman JJ
- Subjects
- Aged, Female, Hematoma epidemiology, Hematoma therapy, Humans, Male, Middle Aged, Postoperative Complications etiology, Prevalence, Retroperitoneal Space, Retrospective Studies, Risk Factors, Cardiac Catheterization adverse effects, Hematoma etiology
- Abstract
Purpose: Retroperitoneal hematoma is an unusual, but potentially serious, complication after cardiac catheterization. The predisposing factors, typical presentation, and clinical course of this iatrogenic complication are identified, and the role of surgery in its treatment is defined., Methods: A retrospective review of 9585 femoral artery catheterizations over a 5-year period allowed identification and evaluation of all patients with retroperitoneal hemorrhage., Results: Retroperitoneal hematoma developed in 45 patients (overall prevalence 0.5%), with the highest frequency after coronary artery stenting (3%). In the group of patients who underwent coronary artery stenting, statistically significant predictors of this complication included protocol for sheath removal, female sex, nadir platelet count, and excessive anticoagulation. Signs and symptoms included suprainguinal tenderness and fullness in 100%, severe back and lower quadrant pain in 64%, and femoral neuropathy in 36%. Most patients were treated successfully with transfusion alone. Seven patients (16%) required operation; in four, hypotension unresponsive to volume resuscitation developed early after catheterization; and, in three, a progressive fall in hematocrit level led to surgery 24 to 72 hours after catheterization., Conclusions: Retroperitoneal hematoma after cardiac catheterization can usually be treated by transfusion alone. A small subset of patients who have development of hypotension unresponsive to volume resuscitation require urgent operation.
- Published
- 1994
- Full Text
- View/download PDF
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