24 results on '"Witt RM"'
Search Results
2. Current Considerations in the Diagnosis and Treatment of Circadian Rhythm Sleep-Wake Disorders in Children.
- Author
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Witt RM, Byars KC, Decker K, Dye TJ, Riley JM, Simmons D, and Smith DF
- Subjects
- Adult, Humans, Child, Sleep physiology, Genetic Predisposition to Disease, Circadian Rhythm physiology, Sleep Disorders, Circadian Rhythm diagnosis, Sleep Disorders, Circadian Rhythm therapy, Sleep Wake Disorders
- Abstract
Circadian Rhythm Sleep-Wake Disorders (CRSWDs) are important sleep disorders whose unifying feature is a mismatch between the preferred or required times for sleep and wakefulness and the endogenous circadian drives for these. Their etiology, presentation, and treatment can be different in pediatric patients as compared to adults. Evaluation of these disorders must be performed while viewed through the lens of a patient's comorbid conditions. Newer methods of assessment promise to provide greater diagnostic clarity and critical insights into how circadian physiology affects overall health and disease states. Effective clinical management of CRSWDs is multimodal, requiring an integrated approach across disciplines. Therapeutic success depends upon appropriately timed nonpharmacologic and pharmacologic interventions. A better understanding of the genetic predispositions for and causes of CRSWDs has led to novel clinical opportunities for diagnosis and improved therapeutics., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.) more...
- Published
- 2023
- Full Text
- View/download PDF
Catalog
3. Sleep and Circadian Disturbances in Children With Neurodevelopmental Disorders.
- Author
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Tamir S, Dye TJ, and Witt RM
- Subjects
- Child, Humans, Sleep, Phenotype, Neurodevelopmental Disorders complications, Brain Diseases, Sleep Wake Disorders complications
- Abstract
Sleep problems are highly prevalent in those with neurodevelopmental disorders (NDDs). We propose this is secondary to multiple factors that directly and indirectly negatively impact sleep and circadian processes in those with NDDs, which in turn, further perturbs development, resulting in a "developmental and sleep/circadian-related encephalopathy." In this review, we discuss select NDDs with known or suspected sleep and circadian phenotypes. We also highlight important considerations when evaluating and treating sleep and circadian disorders in these populations., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.) more...
- Published
- 2023
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4. A Word of Caution: Adenotonsillectomy May Help Reduce Central Apneas, but It Is Not a Treatment for Central Sleep Apnea.
- Author
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Smith DF, Heubi CH, Witt RM, and Dye TJ
- Subjects
- Humans, Adenoidectomy, Sleep Apnea, Central surgery, Sleep Apnea Syndromes surgery, Sleep Apnea, Obstructive surgery, Tonsillectomy adverse effects
- Published
- 2023
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5. Shh-proteoglycan interactions regulate maturation of olfactory glomerular circuitry.
- Author
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Persson L, Witt RM, Galligan M, Greer PL, Eisner A, Pazyra-Murphy MF, Datta SR, and Segal RA
- Subjects
- Animals, Calbindins metabolism, Hedgehog Proteins genetics, Immunohistochemistry, In Situ Hybridization, Mice, Transgenic, Neural Cell Adhesion Molecules metabolism, Neurogenesis physiology, Neurons pathology, Neurons physiology, Olfactory Bulb pathology, Olfactory Bulb physiopathology, Olfactory Marker Protein metabolism, Olfactory Pathways pathology, Olfactory Pathways physiopathology, Organ Size, RNA, Messenger metabolism, Signal Transduction, Hedgehog Proteins metabolism, Olfactory Bulb growth & development, Olfactory Pathways growth & development, Proteoglycans metabolism
- Abstract
The olfactory system relies on precise circuitry connecting olfactory sensory neurons (OSNs) and appropriate relay and processing neurons of the olfactory bulb (OB). In mammals, the exact correspondence between specific olfactory receptor types and individual glomeruli enables a spatially precise map of glomerular activation that corresponds to distinct odors. However, the mechanisms that govern the establishment and maintenance of the glomerular circuitry are largely unknown. Here we show that high levels of Sonic Hedgehog (Shh) signaling at multiple sites enable refinement and maintenance of olfactory glomerular circuitry. Mice expressing a mutant version of Shh (Shh(Ala/Ala)), with impaired binding to proteoglycan co-receptors, exhibit disproportionately small olfactory bulbs containing fewer glomeruli. Notably, in mutant animals the correspondence between individual glomeruli and specific olfactory receptors is lost, as olfactory sensory neurons expressing different olfactory receptors converge on the same glomeruli. These deficits arise at late stages in post-natal development and continue into adulthood, indicating impaired pruning of erroneous connections within the olfactory bulb. In addition, mature Shh(Ala/Ala) mice exhibit decreased proliferation in the subventricular zone (SVZ), with particular reduction in neurogenesis of calbindin-expressing periglomerular cells. Thus, Shh interactions with proteoglycan co-receptors function at multiple locations to regulate neurogenesis and precise olfactory connectivity, thereby promoting functional neuronal circuitry., (© 2014 Wiley Periodicals, Inc.) more...
- Published
- 2014
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6. Heparan sulfate proteoglycans containing a glypican 5 core and 2-O-sulfo-iduronic acid function as Sonic Hedgehog co-receptors to promote proliferation.
- Author
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Witt RM, Hecht ML, Pazyra-Murphy MF, Cohen SM, Noti C, van Kuppevelt TH, Fuller M, Chan JA, Hopwood JJ, Seeberger PH, and Segal RA
- Subjects
- Animals, COS Cells, Cerebellum cytology, Chlorocebus aethiops, Gene Expression Regulation physiology, Glypicans genetics, HEK293 Cells, Hedgehog Proteins genetics, Humans, Mice, Nerve Tissue Proteins, Neural Stem Cells cytology, Cell Proliferation, Cerebellum metabolism, Glypicans metabolism, Hedgehog Proteins metabolism, Neural Stem Cells metabolism, Signal Transduction physiology
- Abstract
Sonic Hedgehog (Shh) signaling is crucial for growth, cell fate determination, and axonal guidance in the developing nervous system. Although the receptors Patched (Ptch1) and Smoothened (Smo) are required for Shh signaling, a number of distinct co-receptors contribute to these critical responses to Shh. Several membrane-embedded proteins such as Boc, Cdo, and Gas1 bind Shh and promote signaling. In addition, heparan sulfate proteoglycans (HSPGs) have also been implicated in the initiation of Shh responses. However, the attributes of HSPGs that function as co-receptors for Shh have not yet been defined. Here, we identify HSPGs containing a glypican 5 core protein and 2-O-sulfo-iduronic acid residues at the nonreducing ends of the glycans as co-receptors for Shh. These HSPG co-receptors are expressed by cerebellar granule cell precursors and promote Shh binding and signaling. At the subcellular level, these HSPG co-receptors are located adjacent to the primary cilia that act as Shh signaling organelles. Thus, Shh binds to HSPG co-receptors containing a glypican 5 core and 2-O-sulfo-iduronic acid to promote neural precursor proliferation. more...
- Published
- 2013
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7. Proteoglycan interactions with Sonic Hedgehog specify mitogenic responses.
- Author
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Chan JA, Balasubramanian S, Witt RM, Nazemi KJ, Choi Y, Pazyra-Murphy MF, Walsh CO, Thompson M, and Segal RA
- Subjects
- Animals, Animals, Newborn, Body Patterning genetics, Bromodeoxyuridine metabolism, Cell Proliferation, Embryo, Mammalian, Fibrinolytic Agents pharmacology, Gene Expression genetics, Gene Expression Regulation, Developmental genetics, Glycosylphosphatidylinositols metabolism, Hedgehog Proteins genetics, Heparin pharmacology, Histones genetics, Histones metabolism, In Situ Nick-End Labeling methods, Kruppel-Like Transcription Factors genetics, Kruppel-Like Transcription Factors metabolism, Mice, Mice, Transgenic, Mutation genetics, Nerve Tissue Proteins genetics, Nerve Tissue Proteins metabolism, Protein Binding drug effects, Protein Binding genetics, Stem Cells classification, Stem Cells physiology, Zinc Finger Protein Gli3, Central Nervous System anatomy & histology, Central Nervous System embryology, Central Nervous System growth & development, Gene Expression Regulation, Developmental physiology, Hedgehog Proteins metabolism, Mitosis genetics, Proteoglycans metabolism
- Abstract
Sonic Hedgehog (Shh) has dual roles in vertebrate development, promoting progenitor cell proliferation and inducing tissue patterning. We found that the mitogenic and patterning functions of Shh can be uncoupled from one another. Using a genetic approach to selectively inhibit Shh-proteoglycan interactions in a mouse model, we found that binding of Shh to proteoglycans was required for proliferation of neural stem/precursor cells, but not for tissue patterning. Shh-proteoglycan interactions regulated both spatial and temporal features of Shh signaling. Proteoglycans localized Shh to specialized mitogenic niches and also acted at the single-cell level to regulate the duration of Shh signaling, thereby promoting a gene expression program that is important for cell division. Because activation of the Shh pathway is a feature of diverse human cancers, selective stimulation of proliferation by Shh-proteoglycan interactions may also figure prominently in neoplastic growth. more...
- Published
- 2009
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8. Olfactory behavioral testing in the adult mouse.
- Author
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Witt RM, Galligan MM, Despinoy JR, and Segal R
- Subjects
- Animals, Mice, Odorants, Sensory Thresholds, Behavior, Animal physiology, Smell physiology
- Abstract
The rodent olfactory system is of increasing interest to scientists, studied, in part, in systems biology because of its stereotyped, yet accessible circuitry. In addition, this area's unique ability to generate new neurons throughout an organism's lifetime makes it an attractive system for developmental and regenerative biologists alike. Such interest necessitates a means for a quick, yet reliable assessment of olfactory function. Many tests of olfactory ability are complex, variable or not specifically designed for mice. Also, some tests are sensitive to memory deficits as well as defects in olfactory abilities, confounding obtained results. Here, we describe a simple battery of tests designed to identify defects in olfactory sensitivity and preference. First, an initial general health assessment allows for the identification of animals suitable for further testing. Second, mice are exposed to various dilutions of scents to ascertain whether there is a threshold difference. Third, mice are presented with various scents, both attractive and aversive, that allow for the assessment of olfactory preference. These simple studies should make the initial characterization of olfactory behavior accessible for labs of varied resources and expertise. more...
- Published
- 2009
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9. Pam (Protein associated with Myc) functions as an E3 ubiquitin ligase and regulates TSC/mTOR signaling.
- Author
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Han S, Witt RM, Santos TM, Polizzano C, Sabatini BL, and Ramesh V
- Subjects
- Adaptor Proteins, Signal Transducing chemistry, Amino Acid Sequence, Animals, Cells, Cultured, Humans, Mixed Function Oxygenases chemistry, Molecular Sequence Data, Mutation, Missense, Neurons metabolism, Phosphorylation, Protein Structure, Tertiary, Rats, Signal Transduction, TOR Serine-Threonine Kinases, Tuberous Sclerosis genetics, Tuberous Sclerosis Complex 2 Protein, Ubiquitin-Conjugating Enzymes metabolism, Ubiquitin-Protein Ligases chemistry, Ubiquitination, Adaptor Proteins, Signal Transducing metabolism, Mixed Function Oxygenases metabolism, Protein Kinases metabolism, Tumor Suppressor Proteins metabolism, Ubiquitin-Protein Ligases metabolism
- Abstract
The tumor suppressor tuberin, encoded by the Tuberous Sclerosis Complex (TSC) gene TSC2, negatively regulates the mammalian target of rapamycin (mTOR) pathway, which plays a key role in the control of cell growth and proliferation. In addition to naturally occurring mutations, several kinases including Akt, RSK1, and ERK are known to phosphorylate and inactivate tuberin. We demonstrate a novel mechanism of tuberin inactivation through ubiquitination by Pam, a putative RING finger-containing E3 ubiquitin (Ub) ligase in mammalian cells. We show that Pam associates with E2 ubiquitin-conjugating enzymes, and tuberin can be ubiquitinated by Pam through its RING finger domain. Tuberin ubiquitination is independent of its phosphorylation by Akt, RSK1, and ERK kinases. Pam is also self-ubiquitinated through its RING finger domain. Moreover, the TSC1 protein hamartin, which forms a heterodimer with tuberin, protects tuberin from ubiquitination by Pam. However, TSC1 fails to protect a disease-associated missense mutant of TSC2 from ubiquitination by Pam. Furthermore, Pam knockdown by RNA interference (RNAi) in rat primary neurons elevates the level of tuberin, and subsequently inhibits the mTOR pathway. Our results provide novel evidence that Pam can function as an E3 Ub ligase toward tuberin and regulate mTOR signaling, suggesting that Pam can in turn regulate cell growth and proliferation as well as neuronal function through the TSC/mTOR pathway in mammalian cells. more...
- Published
- 2008
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10. A novel computational approach for automatic dendrite spines detection in two-photon laser scan microscopy.
- Author
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Cheng J, Zhou X, Miller E, Witt RM, Zhu J, Sabatini BL, and Wong ST
- Subjects
- Algorithms, Microscopy, Confocal, Photons, Dendritic Spines ultrastructure, Image Processing, Computer-Assisted methods
- Abstract
Background: Recent research has shown that there is a strong correlation between the functional properties of a neuron and its morphologic structure. Current morphologic analyses typically involve a significant component of computer-assisted manual labor, which is very time-consuming and is susceptible to operator bias. The existing semi-automatic approaches largely reduce user efforts. However, some manual interventions, such as setting a global threshold for segmentation, are still needed during image processing., Methods: We present an automated approach, which can greatly help neurobiologists obtain quantitative morphological information about a neuron and its spines. The automation includes an adaptive thresholding method, which can yield better segment results than the prevalent global thresholding method. It also introduces an efficient backbone extraction method, a SNR based, detached spine component detection method, and an attached spine component detection method based on the estimation of local dendrite morphology., Results: The morphology information obtained both manually and automatically are compared in detail. Using the Kolmogov-Smirnov test, we find a 99.13% probability that the dendrite length distributions are the same for the automatic and manual processing methods. The spine detection results are also compared with other existing semi-automatic approaches. The comparison results show that our approach has 33% fewer false positives and 77% fewer false negatives on average., Conclusions: Because the proposed detection algorithm requires less user input and performs better than existing algorithms, our approach can quickly and accurately process neuron images without user intervention. more...
- Published
- 2007
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11. Dendritic spine detection using curvilinear structure detector and LDA classifier.
- Author
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Zhang Y, Zhou X, Witt RM, Sabatini BL, Adjeroh D, and Wong ST
- Subjects
- Computer Graphics, Discriminant Analysis, Numerical Analysis, Computer-Assisted, Reproducibility of Results, Sensitivity and Specificity, Ultrasonography, Algorithms, Artificial Intelligence, Dendrites diagnostic imaging, Image Enhancement methods, Image Interpretation, Computer-Assisted methods, Imaging, Three-Dimensional methods, Pattern Recognition, Automated methods
- Abstract
Dendritic spines are small, bulbous cellular compartments that carry synapses. Biologists have been studying the biochemical pathways by examining the morphological and statistical changes of the dendritic spines at the intracellular level. In this paper a novel approach is presented for automated detection of dendritic spines in neuron images. The dendritic spines are recognized as small objects of variable shape attached or detached to multiple dendritic backbones in the 2D projection of the image stack along the optical direction. We extend the curvilinear structure detector to extract the boundaries as well as the centerlines for the dendritic backbones and spines. We further build a classifier using Linear Discriminate Analysis (LDA) to classify the attached spines into valid and invalid types to improve the accuracy of the spine detection. We evaluate the proposed approach by comparing with the manual results in terms of backbone length, spine number, spine length, and spine density. more...
- Published
- 2007
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12. Retroviral particles produced from a stable human-derived packaging cell line transduce target cells with very high efficiencies.
- Author
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Davis JL, Witt RM, Gross PR, Hokanson CA, Jungles S, Cohen LK, Danos O, and Spratt SK
- Subjects
- 3T3 Cells virology, Animals, Cell Line, Granulocyte-Macrophage Colony-Stimulating Factor genetics, Granulocyte-Macrophage Colony-Stimulating Factor metabolism, Humans, Kidney embryology, Melanoma genetics, Melanoma metabolism, Melanoma virology, Mice, Recombinant Proteins genetics, Recombinant Proteins metabolism, beta-Galactosidase genetics, beta-Galactosidase metabolism, Kidney cytology, Kidney virology, Retroviridae genetics, Transduction, Genetic
- Abstract
The goal of this work was to determine whether a stable 293 amphotropic packaging line, which we have designated 293-SPA, is useful for the production of high-titer stable virus by comparison to the murine psiCRIP line. Here, we report our unexpected findings that particles derived from the 293-SPA line transduce target cells (both NIH-3T3 cells and primary melanoma cells) with greatly enhanced efficiencies (at least 10-fold) compared to particles derived from the psiCRIP packaging line. We show that the presence of a transferable inhibitor in the psiCRIP line at least partially accounts for this dramatic difference in transduction efficiency. This work has important implications for improving the efficiency of retrovirus-mediated gene transfer in general as well as in the design of new packaging cell lines. more...
- Published
- 1997
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13. Direct comparison of fluorine-18-FDG SPECT, fluorine-18-FDG PET and rest thallium-201 SPECT for detection of myocardial viability.
- Author
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Burt RW, Perkins OW, Oppenheim BE, Schauwecker DS, Stein L, Wellman HN, and Witt RM
- Subjects
- Deoxyglucose analogs & derivatives, Fluorine Radioisotopes, Fluorodeoxyglucose F18, Humans, Prospective Studies, Thallium Radioisotopes, Coronary Disease diagnostic imaging, Heart diagnostic imaging, Tomography, Emission-Computed, Tomography, Emission-Computed, Single-Photon
- Abstract
Unlabelled: Twenty consecutive patients were evaluated for presumptive myocardial viability using rest TI-SPECT, FDG-PET and FDG-SPECT. The FDG studies were performed after rest TI-SPECT to guide intervention or medical management., Methods: Twenty patients with proven coronary artery disease, either known or suspected to have previous myocardial infarction and persistent perfusion defects shown by rest reinjection TI-SPECT, underwent FDG-PET and subsequent FDG-SPECT with a three-detector SPECT camera. FDG-PET and SPECT images were compared by five observers to determine if any fixed thallium segments were visualized by either FDG imaging method., Results: Thirteen of 60 fixed segments were shown probably viable by FDG-SPECT (8 of 20 patients) and 14 of 60 by FDG PET (7 of 20 patients). Two patients had fixed thallium segments found probably viable with FDG by SPECT alone and one by PET alone., Conclusion: FDG is shown to provide additional information about myocardial viability. Both SPECT, using a three-detector camera, and PET with a specialized instrument are equally effective for imaging FDG in this application. more...
- Published
- 1995
14. Acetazolamide enhanced single photon emission computed tomography (SPECT) evaluation of cerebral perfusion before and after carotid endarterectomy.
- Author
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Cikrit DF, Burt RW, Dalsing MC, Lalka SG, Sawchuk AP, Waymire B, and Witt RM
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- Aged, Aged, 80 and over, Blindness diagnostic imaging, Carotid Stenosis diagnostic imaging, Cerebrovascular Disorders physiopathology, Cerebrovascular Disorders surgery, Female, Humans, Ischemic Attack, Transient diagnostic imaging, Male, Middle Aged, Retrospective Studies, Acetazolamide, Cerebrovascular Circulation physiology, Cerebrovascular Disorders diagnostic imaging, Endarterectomy, Carotid, Tomography, Emission-Computed, Single-Photon
- Abstract
Twenty-five patients were tested before and after carotid endarterectomy with resting and acetazolamide enhanced single photon emission computed tomography (SPECT) scans with hexamethyl propyleneamine oxine (HMPAO) or iofetamine hydrochloride I123 (123I labeled IMP), both widely available radiopharmaceuticals. Twenty preoperative SPECT studies were asymmetric, revealing focal or diffuse decreased perfusion reserve, and 13 also demonstrated infarcts. Five patients had symmetric (normal) studies. After carotid endarterectomy, 22 cases had changed flow distribution patterns. Usually improvement of reactivity ipsilateral occurred to the area operated on. In four, contralateral improvement was also found. Three of the patients who had preoperative symmetrical scans had increased ipsilateral reactivity after surgery indicating previous global loss of reactivity. Acetazolamide SPECT scans demonstrate a decreased perfusion reserve in 20 patients with carotid artery stenosis, indicating reduced perfusion and poor collateral circulation. Postoperative studies confirm improvement by demonstrating recovery of vascular reactivity in 84% of the patients. Acetazolamide enhanced SPECT scans may be helpful in providing objective evidence for selection of patients for carotid endarterectomy, especially in those who have an 80% carotid artery stenosis, but are asymptomatic. more...
- Published
- 1992
15. Carotid artery disease: evaluation with acetazolamide-enhanced Tc-99m HMPAO SPECT.
- Author
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Burt RW, Witt RM, Cikrit DF, and Reddy RV
- Subjects
- Adult, Aged, Aged, 80 and over, Arterial Occlusive Diseases physiopathology, Carotid Artery Diseases complications, Carotid Artery Diseases physiopathology, Cerebrovascular Circulation drug effects, Cerebrovascular Disorders etiology, Female, Humans, Ischemic Attack, Transient diagnostic imaging, Ischemic Attack, Transient drug therapy, Ischemic Attack, Transient physiopathology, Male, Middle Aged, Technetium Tc 99m Exametazime, Acetazolamide, Arterial Occlusive Diseases diagnostic imaging, Carotid Artery Diseases diagnostic imaging, Organotechnetium Compounds, Oximes, Tomography, Emission-Computed, Single-Photon
- Abstract
Sixty patients were studied for carotid artery disease and were further evaluated with hexamethyl-propyleneamine oxime (HMPAO) single photon emission computed tomography (SPECT) both at baseline (with the patient resting) and after administration of acetazolamide (ACZ). Of these 60 patients, 58 (97%) had symptoms and 49 (82%) had stenoses greater than 70% in at least one internal carotid vessel. Nine patients (15%) had symmetric findings on baseline examinations and at SPECT with ACZ. Thirty-two patients (53%) had asymmetric findings on baseline, but in 24 of these patients (75%) additional lesions were observed after ACZ administration. Nineteen patients (32%) had asymmetric findings only after ACZ was administered. HMPAO SPECT with ACZ allows detection of diminished cerebral perfusion reserve that is not found when HMPAO SPECT is performed with the patient at rest. This procedure helps provide an objective evaluation of the hemodynamic effects of carotid stenosis. more...
- Published
- 1992
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16. Increased brain retention of Tc-99m HMPAO following acetazolamide administration.
- Author
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Burt RW, Witt RM, Cikrit D, and Carter J
- Subjects
- Humans, Male, Middle Aged, Organotechnetium Compounds, Oximes, Stimulation, Chemical, Technetium Tc 99m Exametazime, Tomography, Emission-Computed, Single-Photon, Acetazolamide, Brain diagnostic imaging, Cerebrovascular Circulation drug effects, Cerebrovascular Disorders diagnostic imaging
- Abstract
Sixty-five patients referred for Tc-99m HMPAO SPECT brain perfusion studies had measurements of global Tc-99m HMPAO retention after injection at rest and after acetazolamide pretreatment. Acetazolamide produced relative changes in Tc-99m HMPAO retention similar to those previously reported with Xe-133 regional cerebral blood flow (rCBF) measurements. This addition to imaging protocols allows another objective evaluation of the cerebral vascular reserve. more...
- Published
- 1991
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17. Initial experience with a radiology imaging network to newborn and intensive care units.
- Author
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Witt RM, Cohen MD, and Appledorn CR
- Subjects
- Computer Systems, Humans, Computer Communication Networks, Intensive Care Units, Nurseries, Hospital, Radiology Information Systems
- Abstract
A digital image network has been installed in the James Whitcomb Riley Hospital for Children on the Indiana University Medical Center to create a limited all digital imaging system. The system is composed of commercial components, Philips/AT&T CommView system, (Philips Medical Systems, Shelton, CT; AT&T Bell Laboratories, West Long Beach, NJ) and connects an existing Philips Computed Radiology (PCR) system to two remote workstations that reside in the intensive care unit and the newborn nursery. The purpose of the system is to display images obtained from the PCR system on the remote workstations for direct viewing by referring clinicians, and to reduce many of their visits to the radiology reading room three floors away. The design criteria includes the ability to centrally control all image management functions on the remote workstations to relieve the clinicians from any image management tasks except for recalling patient images. The principal components of the system are the Philips PCR system, the acquisition module (AM), and the PCR interface to the Data Management Module (DMM). Connected to the DMM are an Enhanced Graphics Display Workstation (EGDW), an optical disk drive, and a network gateway to an ethernet link. The ethernet network is the connection to the two Results Viewing Stations (RVS) and both RVSs are approximately 100 m from the gateway. The DMM acts as an image file server and an image archive device. The DMM manages the image data base and can load images to the EGDW and the two RVSs. The system has met the initial design specifications and can successfully capture images from the PCR and direct them to the RVSs.(ABSTRACT TRUNCATED AT 250 WORDS) more...
- Published
- 1991
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18. Early menopausal changes in bone mass and sex steroids.
- Author
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Johnston CC Jr, Hui SL, Witt RM, Appledorn R, Baker RS, and Longcope C
- Subjects
- Adult, Androstenedione blood, Calcium blood, Calcium-Binding Proteins blood, Estradiol blood, Estrone blood, Fasting, Female, Follicle Stimulating Hormone blood, Humans, Luteinizing Hormone blood, Menstruation, Middle Aged, Osteocalcin, Progesterone blood, Retrospective Studies, Testosterone blood, Bone and Bones anatomy & histology, Gonadal Steroid Hormones blood, Menopause
- Abstract
Eighty-four healthy perimenopausal and early postmenopausal women were divided into four groups: group A, those with slightly irregular menstrual periods and plasma FSH below 40 mIU/ml; group B, those with irregular periods and FSH above 40 mIU/ml; group C, those whose last menstrual period was within 1 yr of study; and, group D, those whose last menstrual period was between 12 and 55 months before the study. Plasma concentrations of estrone and estradiol progressively decreased in groups B, C and D compared to those in A in parallel with a decrease in the production rates, and FSH and LH were significantly increased. There was little change in the concentration of androstenedione or testosterone. Vertebral bone mass was significantly decreased in groups B, C, and D compared to that in A, and radial bone mass was decreased in group D. There was a significantly positive correlation between plasma estrone and estradiol and bone mass at both the radius and vertebra. Increased bone remodeling was suggested by increases in serum calcium and bone gla protein. These data suggest that bone loss, at least from the spine, may begin before menses cease and is correlated with decreases in estrogen production and increases in bone remodeling. more...
- Published
- 1985
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19. Soft-tissue fluid determination by dichromatic absorptiometry.
- Author
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Wolberg WH, Witt RM, Moylan JA, and Mazess RB
- Subjects
- Animals, Body Composition, Body Water analysis, Body Weight, Dogs, Humans, Methods, Risk, Surgical Procedures, Operative, Body Fluids analysis, Forearm analysis
- Abstract
Dichromatic absorptiometry (DA) in a noninvasive method for individually determining the amount of lipid, bone mineral, and protein and water present in a mixture by differential attenuation of radiation beams emitted from a dual photon source. The physics involved permit these components to be determined extremely accurately and precisely. The present study investigated the ability of DA limb scans to measure changes in total body water produced in dogs and in patients. Dichromatic absorptiometry was determined to be a valid method of measuring changes in total body water content as reflected by limb fluid content changes. Precision was limited by the accuracy in positioning the limb for repeated scanning. Dichromatic absorptiometry has the potential of becoming a clinically useful instrument for measuring fluid content changes in limbs produced either by changes in total body water content or by conditions causing limb edema. more...
- Published
- 1977
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20. Computer-assisted on-call scheduling.
- Author
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Conrad GR, Witt RM, and Cockerill EM
- Subjects
- Personnel Management, Personnel Staffing and Scheduling, Radiology, Software
- Published
- 1988
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21. Epoxy-resin-based tissue substitutes.
- Author
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White DR, Martin RJ, Witt RM, and Masterson ME
- Subjects
- Humans, Radiotherapy Dosage, United States, Epoxy Resins, Models, Structural
- Published
- 1978
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22. Clinical comparison of indium-111 acetylacetone and indium-111 tropolone granulocytes.
- Author
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Schauwecker DS, Burt RW, Park HM, Mock BH, Witt RM, Tobolski MM, and Wellman HN
- Subjects
- Adolescent, Adult, Aged, Aged, 80 and over, Female, Humans, Infections diagnostic imaging, Male, Middle Aged, Osteomyelitis diagnostic imaging, Radionuclide Imaging, Cycloheptanes, Granulocytes, Indium, Ketones, Pentanones, Radioisotopes, Tropolone
- Abstract
This clinical study compares the efficacy of two 111In white blood cells preparations. Seventy-six patients were imaged after an injection of granulocytes (GRAN) isolated on a Ficoll-Hypaque gradient and labeled with [111In]acetylacetone (ACAC) in saline; 105 patients were imaged after an injection of GRAN isolated on a metrizamide-plasma gradient and labeled with [111In]tropolone (TROP) in plasma. Early (2-4 hr), intermediate (4-6 hr), and delayed (24 hr) images were obtained. The specificity was quite high (94-100%) in both preparations and no statistical differences could be found. The sensitivity for ACAC-GRAN for the early, intermediate, and delayed images were 39%, 63%, and 64%, respectively; for TROP-GRAN it was 80%, 89%, and 92%, respectively. In all cases the TROP-GRAN images were significantly more sensitive than the ACAC-GRAN images obtained at the same time after injection (p less than 0.001 for early and delayed images, 0.01 less than p less than 0.025 for intermediate images). For ACAC-GRAN the intermediate and delayed images were significantly more sensitive than the early images, while no significant difference could be found for TROP-GRAN. In a blinded experiment, the ability of TROP-GRAN to demonstrate a lesion was compared to that of ACAC-GRAN. TROP-GRAN demonstrated the lesions better than ACAC-GRAN, both in the early and late images (p less than 0.001). TROP-GRAN visualization scores at 4-6 hr equaled those obtained 24 hr after injection. In conclusion, GRAN separated and labeled in plasma with TROP are superior to those separated and labeled in saline with ACAC in three ways: higher visualization scores, earlier visualization of the lesion, and greater sensitivity. more...
- Published
- 1986
23. Photon absorptiometry of soft tissue and fluid content: the method and its precision and accuracy.
- Author
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Witt RM and Mazess RB
- Subjects
- Americium, Body Fluids analysis, Bone and Bones analysis, Elementary Particles, Humans, Iodine Radioisotopes, Methods, Body Composition
- Abstract
Dichromatic absorptiometry (DA) is a new, non-invasive method for determining soft tissue (STC) and fluid content (FC), and their changes. The technique uses linear transmission scans made across the limbs with a congruent 125I and 241Am dual-photon source and a NaI(TI)--PMT detector. Patient measurements could be made at the bedside with the mobile system. Factors affecting the precision and accuracy were evaluated theoretically and experimentally. Repositioning and subject motion were the greatest sources of variation and limited the precision to 2--3% in normals and 3--7% in patients; instrumental variation was 0.5%. The accuracy was 4% for typical (p10%) fluid changes observed in vivo. The ease, simplicity and small errors of the technique suggest its utility in monitoring the time course and degree of fluid changes in patients. more...
- Published
- 1978
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24. The study of burn wound edema using dichromatic absorptiometry.
- Author
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Demling RH, Mazess RB, Witt RM, and Wolberg WH
- Subjects
- Absorption, Animals, Body Fluids metabolism, Bone and Bones metabolism, Burns metabolism, Edema etiology, Edema metabolism, Lipid Metabolism, Proteins metabolism, Sheep, Water metabolism, Burns complications, Edema diagnosis
- Abstract
Burn wound edema is a source of major morbidity and mortality. To quantitatively study this edema, we have devised a noninvasive method called Dichromatic Absorptiometry (DA) which is precise (2-3%) and accurate (r equal to 0.99) in measuring changes in tissue fluid. A scanning technique using a dual photon source, 125I and 241Am, is used. The variable attenuation of the two photon energies allows for selective mass measurements of fluid, protein, lipid, and bone. In limbs with thermal injury the correlation of DA changes in fluid mass with circumference was (r equal to 0.97), but DA was more sensitive. In deep second- and third-degree burns, edema formation was maximum between 12 and 18 hours postburn with 80% of maximum already present at 4 hours. Resorption was complete by 1 week in second-degree burns, but significantly delayed in third-degree burns. Superimposed infection produced persistent edema. more...
- Published
- 1978
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