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Diverse subtypes of nicotinic acetylcholine receptors (nAChRs), including fast-desensitizing alpha7-containing receptors thought to be Ca2+-permeable, are expressed in the CNS, where they appear to regulate cognitive processing and synaptic plasticity. To understand the physiological role of nAChRs in regulating neuronal excitability, it is important to know the distribution of functional receptors along the surface of neurons, whether they can increase [Ca2+]i, and/or are regulated by Ca2+. We mapped the distribution of receptors on the membrane of rat hippocampal CA1 stratum radiatum interneurons and pyramidal cells in acute slices by recording nAChR-mediated currents elicited by local UV laser-based photolysis of caged carbachol in patch-clamped neurons. The local application (approximately 7 microm patches) allowed mapping of functional nAChRs along the soma and dendritic tree, whereas the fast uncaging minimized the effects of desensitization of alpha7-containing nAChRs and allowed us to measure the kinetics of responses. The alpha7-containing nAChRs were the predominant subtype on interneurons, and were located primarily at perisomatic sites (<70 microm from the soma; in contrast to the more uniform distribution of glutamate receptors); no currents were detectable on pyramidal neurons. The activation of nAChRs increased [Ca2+]i, indicating that these native receptors in acute slices are significantly Ca2+-permeable, consistent with previous observations made with recombinant receptors. In addition, they exhibited strong desensitization, the rate of recovery from which was controlled by [Ca2+]i. Our results demonstrate the strategic location and Ca2+ regulation of alpha7-containing nAChRs, which may contribute to understanding their involvement in hippocampal plasticity.

Introduction: The implantable cardioverter defibrillator (ICD) is commonly used to treat patients with documented sustained ventricular tachycardia (VT) or ventricular fibrillation (VF). Arrhythmia recurrence rates in these patients are high, but which patients will receive a therapy and the forms of arrhythmia recurrence (VT or VF) are poorly understood., Methods and Results: The therapy delivered by the ICD was examined in 449 patients randomized to ICD therapy in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Trial. Events triggering ICD shocks or antitachycardia pacing (ATP) were reviewed for arrhythmia diagnosis, clinical symptoms, activity at the onset of the arrhythmia, and appropriateness and results of therapy. Both shock and ATP therapies were frequent by 2 years, with 68% of patients receiving some therapy or having an arrhythmic death. An appropriate shock was delivered in 53% of patients, and ATP was delivered in 68% of patients who had ATP activated. The first arrhythmia treated in follow-up was diagnosed as VT (63%), VF (13%), supraventricular tachycardia (18%), unknown arrhythmia (3%), or due to ICD malfunction or inappropriate sensing (3%). Acceleration of an arrhythmia by the ICD occurred in 8% of patients who received any therapy. No physical activity consistently preceded arrhythmias, nor did any single clinical factor predict the symptoms of the arrhythmia., Conclusion: Delivery of ICD therapy in AVID patients was common, primarily due to VT. Inappropriate ICD therapy occurred frequently. Use of ICD therapy as a surrogate endpoint for death in clinical trials should be avoided.

Animal-transfer and cage-changing stations are portable downdraft-filtered clean benches that have been specifically modified for small-rodent handling and cage changing from two or more sides, and that are advertised by their manufacturers as providing improved laboratory animal allergen control. The authors evaluated the dust containment capability of three such devices under exaggerated challenge conditions, compared design features, and conclude that animal-transfer stations can be a useful addition to an institutional laboratory animal allergy control program.

Conantokin-G (con-G) is a small, gamma-carboxyglutamic acid (Gla)-containing peptide that functions neurophysiologically by inhibiting the N-methyl-d-aspartate receptor (NMDAR). In the current study, the receptor binding properties of an alanine-rich, Gla-deficient con-G variant, Ala-con-G, were assessed following tracer radioiodination with 125I. Direct binding experiments with [125I]Ala-con-G yielded a single site defined by a Kd value of 516 +/- 120 nm. Displacement of [125I]Ala-con-G binding by Ala-con-G resulted in 100% displacement with an IC50 value of 564 +/- 33 nm, while heterologous displacement by con-G[S16Y], con-G, con-T, and con-R[1-17] yielded IC50 values in the range of 15-45 microm. No displacement was observed with d-gamma-con-G or con-G[L5A], analogs that are inactive at NMDARs. Specific [125I]Ala-con-G binding was displaced by NMDA and 2-amino-5-phosphopentanoic acid in a dose-dependent manner, suggesting an interaction at the glutamate binding site. The direct binding of [125I]Ala-con-G to adult rat brain sections revealed an anatomical distribution of binding sites in all regions known to contain the NR2B subunit of the NMDAR. These results constitute the only known demonstration of the direct binding of a radiolabeled conantokin to the NMDARs present in rat brain membrane preparations and rat brain sections, and suggest that radiolabeled Ala-con-G, and similar conantokin derivatives, may find utility as probes of NMDARs in a variety of systems.

Background: A 10-J energy safety margin has traditionally been used in programming implantable cardioverter defibrillators (ICDs). The Low Energy Safety Study (LESS) tests the hypothesis that programming shocks to lower energy margins is safe and effective., Methods: Patients with standard ICD indications undergo defibrillation threshold testing (DFT) at the time of ICD implant, with reconfirmation of lowest successful energy twice (DFT++). Patients are randomized to 2 groups: the first has the initial 2 shocks for ventricular fibrillation conversion programmed at 2 energy steps above DFT++ (typically 4-6 J, maximum 10 J) with subsequent shocks at maximum energy, and the second has all shocks programmed at maximum energy. Patients are followed up every 3 months for 2 years to assess shock conversion efficacy of spontaneous arrhythmias. In a subgroup of patients, there is a second randomization to energy levels of 0, 1, 2, 3, or 4 steps above implant DFT++ for conversion testing of 3 induced ventricular fibrillation episodes at prehospital discharge, 3 months, and 12 months after implant., Results: Enrollment is complete (702 patients), but follow-up results are pending. There were no significant variations in implant indications and baseline antiarrhythmic drug use over the 3-year enrollment period, although an increase in the percentage of dual-chamber ICDs implanted occurred, with the majority (65%) of implanted ICDs being dual-chamber devices by the end of the enrollment period., Conclusion: The results of LESS should facilitate the development of algorithms for programming ICD energy safety margins.

The characterization of conantokin-T (con-T), conantokin-R (con-R), and variants thereof, using the whole-cell patch clamp technique, was undertaken to evaluate the contribution of various residues towards the onset and recovery of N-methyl-D-aspartate (NMDA) receptor inhibition in cultured embryonic murine hippocampal neurons. The results obtained indicate that the two most C-terminal gamma-carboxyglutamic acid (Gla) residues of the conantokins, while not essential for activity, provided for more tenacious binding to the receptor. Specifically, con-T[gamma10K/gamma14K] and con-R[gamma11A/gamma15A] displayed 5.6- and 8.4-fold decreases in tau(off), respectively, compared to the parent peptides. For the truncated con-T variants, con-T[1-9/Q6G], and a sarcosine (Src)-containing species, con-T[1-9/G1Src/Q6G], the tau(off) was over 80- and 40-fold faster, respectively, compared to con-T. For the latter peptide, the coapplication of 300 microM spermine enhanced the onset rate constant from 3.1x10(3)M(-1) x s(-1) to 12.6x10(3)M(-1) x s(-1). From analysis of equilibrium dose-inhibition curves using the Cheng-Prusoff equation, a K(i) value of 1.1 microM for the peptide was obtained. Con-T[1-9/G1Src/Q6G] demonstrated an apparent competitive mode of inhibition relative to NMDA. Schild analysis of the data yielded an equilibrium dissociation constant of 2.4 microM for the interaction of con-T[1-9/G1Src/Q6G] with the receptor.

Introduction: A prospective registry and substudy were conducted in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Study to clarify the prognosis and recurrent event rate, risk factors, and impact of implantable cardioverter defibrillator (ICD) therapy in patients with unexplained syncope, structural heart disease, and inducible ventricular tachyarrhythmias., Methods and Results: Included in the AVID registry were patients from all participating sites who had "out of hospital syncope with structural heart disease and EP-inducible VT/VF with symptoms." In addition, 13 collaborating sites provided more in-depth clinical and electrophysiologic data as part of a formal prospective substudy. Patients in the substudy were followed by local investigators for recurrent arrhythmic events and mortality. Registry patients were tracked for fatal outcomes by the National Death Index. A total of 429 patients with syncope were entered in the AVID registry, of whom 80 participated in the substudy. Of the substudy patients, 21 patients (26%) had inducible polymorphic ventricular tachycardia/ventricular fibrillation (VT/VF), 11 patients (14%) had sustained monomorphic VT <200 beats/min, and 48 patients (60%) had sustained monomorphic VT > or = 200 beats/min. The ICD was used as sole therapy in 75% of the syncope substudy patients (and with antiarrhythmic drug in an additional 9%) and in 59% of the syncope registry patients. Survival rates at 1 and 3 years were 93% and 74% for the substudy patients and 90% and 74% for the registry patients, respectively. Survival of the syncope substudy patients (predominantly treated by ICD) was similar to the VT patients treated by ICD and superior to the VT patients treated by an antiarrhythmic drug (P = 0.05) in the randomized main trial. Mortality events in the substudy were marginally predicted by ejection fraction (P = 0.06) but not by electrophysiologic study-induced arrhythmia. The significant predictor of increased mortality in the registry was age (P = 0.003) and of reduced mortality was treatment with ICD (P = 0.006)., Conclusion: The results of these analyses support the role of the ICD as primary antiarrhythmic therapy in patients with unexplained syncope, structural heart disease, and inducible VT/VF at electrophysiologic study.

The involvement of the glutamate-glycine activated ion channels of the NMDA receptor in various neurophysiological processes has made this ion channel the focus of intense research. The excessive release of glutamate in a variety of neuronal hypoxic conditions implicates the NMDA receptor in a number of neuropatholological states, such as stroke, chronic pain, Parkinson's disease, Alzheimer's disease, ALS, and epilepsy, among others, thus making this receptor a prime drug target candidate. A variety of agents are known to be effective in opening and closing of the ion channels of this receptor, among the latter group of agents is the peptidic conantokins. Through the use of electrophysiological measurements with a number of cell types containing natural and recombinant subunits of the NMDA receptor, much knowledge is evolving regarding the mechanism of action of activators and inhibitors of the NMDA receptor ion channels. In addition, structure-function studies of the conantokins in these systems have been revealing in terms of their complimentary sites on the NMDA receptor. These relationships serve as the main focus of this review.

Whole cell voltage clamp recordings were performed to assess the ability of conantokin-G (con-G), conantokin-T (con-T), and a 17-residue truncated form of conantokin-R (con-R[1-17]) to inhibit N-methyl-d-aspartate (NMDA)-evoked currents in human embryonic kidney 293 cells transiently expressing various combinations of NR1a, NR1b, NR2A, and NR2B receptor subunits. Con-T and con-R[1-17] attenuated ion currents in cells expressing NR1a/NR2A or NR1a/NR2B. Con-G did not affect NMDA-evoked ionic currents in cells expressing NR1a/NR2A, but it showed inhibitory activity in cells expressing NR1a/NR2B receptors and the triheteromeric combination of NR1a/NR2A/NR2B. An Ala-rich con-G analog, con-G[Q6G/gamma7K/N8A/gamma10A/gamma14A/K15A/S16A/N17A] (Ala/con-G, where gamma is Gla), in which all nonessential amino acids were altered to Ala residues, manifested subunit specificity similar to that of con-G, suggesting that the replaced residues are not responsible for selectivity in the con-G framework. A sarcosine-containing con-T truncation analog, con-T[1-9/G1Src/Q6G], inhibited currents in NR1a/NR2A and NR1a/NR2B receptors, eliminating residues 10-21 as mediators of the broad subunit selectivity of con-T. In contrast to the null effects of con-G and Ala/con-G at a NR1a/NR2A-containing receptor, some inhibition ( approximately 40%) of NMDA-evoked currents was effected by these peptides in cells expressing NR1b/NR2A. This finding suggests that the presence of exon 5 in NR1b plays a role in the activity of the conantokins. Analysis of various conantokin analogs demonstrated that Leu(5) of con-G is an important determinant of conantokin selectivity. Taken as a whole, these results suggest that the important molecular determinants on conantokins responsible for NMDA receptor activity and specificity are discretely housed in specific residues of these peptides, thus allowing molecular manipulation of the NMDA receptor inhibitory properties of the conantokins.

Several derivatives of conantokin-T (con-T), a naturally occurring, gamma-carboxyglutamate (Gla)-containing peptide with NMDA receptor (NMDAR) antagonist properties, were synthesized and evaluated for their ability to displace [(3)H]MK-801 from adult rat forebrain membranes. Analyses of progressive C-terminal truncation analogs of the parent 21-mer revealed gradual losses in activity with decreased chain length. In this series, con-T[1-8] was identified as the shortest variant capable of manifesting inhibitory activity (< 1% of the parent peptide). Ala substitution studies of individual residues identified Gly1, Gla3, Met8 and Leu12 as important for activity, while Glu2, Gla4 and Tyr5 were shown to be essential in this regard. The effect of side-chain length and charge in the N-terminal region was probed by single amino acid replacements. No correlation was observed between potencies and circular dichroism-derived helical contents of the con-T derivatives. Further elaboration of structure-function relationships in con-T was effected through the design and synthesis of helically constrained and destabilized analogs. The results of the current study were compared with those of a previous investigation on con-G, a related conantokin. Substantial differences in activity requirements were noted between the peptides, particularly in the C-terminal regions. Chimeras of con-T and con-G were generated and revealed virtually no interchangeability of residues between these two peptides. Finally, single amino acid substitutions that resulted in analogs with enhanced inhibitory properties were combined to yield superior conantokin-based NMDAR inhibitors.

The trisomy 16 (Ts16) mouse is an animal model for human trisomy 21 (Down's syndrome). The gene encoding the NR2A subunit of the NMDA receptor has been localized to mouse chromosome 16. In the present study, western blot analysis revealed a 2.5-fold increase of NR2A expression in cultured Ts16 embryonic hippocampal neurons. However, this increase did not affect the properties of NMDA-evoked currents in response to various modulators. The sensitivity of NMDA receptors to transient applications of NMDA, spermine, and Zn(2+) was investigated in murine Ts16 and control diploid cultured embryonic hippocampal neurons. Peak and steady-state currents evoked by NMDA were potentiated by spermine at concentrations < 1 mM, and inhibited by Zn(2+) in a dose-dependent and voltage-independent manner. No marked difference was observed between Ts16 and control diploid neurons for any of these modulators with regard to IC(50) and EC(50) values or voltage dependency. Additionally, inhibition by the NR2B selective inhibitor, ifenprodil, was similar. These results demonstrate that NMDA-evoked currents are not altered in cultured embryonic Ts16 neurons and suggest that Ts16 neurons contain similar functional properties of NMDA receptors as diploid control neurons despite an increased level of NR2A expression.

General modalities of analyses that have been used for ICD studies are reviewed. Published "typical" examples are briefly described. The historical cohort method is exemplified with previously unpublished data from the Seattle Cardiac Arrest Survivor database. The AVID Study database is used to compare the results obtained from nonrandomized methodologies with randomized methodologies. Particular issues related to the use of the ICD for example, mode of death, inability to blind, selection practice, and treatment decision times make this a natural pedagogic platform.

Ultraviolet (UV) light boxes ("transilluminators") are commonly used in molecular biology laboratories for visualizing ethidium bromide-intercalated nucleic acids separated under electric current in electrophoretic gels. These devices typically have peak outputs at 254 or 312 nm, well within the UV-C and -B regions that are biologically active and capable of damaging skin. Field evaluations of laboratory transilluminators under actual conditions of use indicate that the UV light emitted from transilluminators is an identifiable and potentially significant occupational hazard for many laboratory workers, as is the high frequency of workstation surface contamination with ethidium bromide, a known mutagen. Fortunately, these hazards can be relatively easily controlled through worker training and the regular use of basic personal protective equipment.

Conantokin-G (con-G) and conantokin-T (con-T) are small (17 and 21 amino acids, respectively) gamma-carboxyglutamate (Gla) containing peptides derived from the venoms of marine cone snails that are potent and selective inhibitors of N-methyl-D-aspartate (NMDA) receptors. In this study, the effects of con-G and con-T on NMDA-evoked responses were evaluated in mouse primary hippocampal neuronal cultures using the whole-cell patch-clamp technique. Under equilibrium conditions, NMDA-induced currents were inhibited by con-G and con-T (10 nM-100 microM) in a dose-dependent manner while maintaining a holding potential of -70 mV. In the presence of saturating amounts of NMDA (100 microM) and glycine (1 microM), the IC50 values obtained were 487 +/- 85 nM for con-G and 1030 +/- 130 nM for con-T. NMDA (10 microM-1 mM) dose-response curves produced in the presence of con-G or con-T (1 or 3 microM) resulted in a downward shift of the current response at saturation with NMDA, without affecting the EC50. The maximum response obtainable in the absence of peptide could not be achieved by increasing concentrations of NMDA. The same effect was also observed for conantokin inhibition of spermine-potentiated responses. Association rate constants (k(on)) for the peptides were determined in the presence of NMDA and glycine, with and without the addition of spermine. Using a single binding site bimolecular model, k(on) values were 3.1 +/- 0.2 x 10(3) M(-1) s(-1) for con-G and 3.2 +/- 0.1 x 10(3) M(-1) s(-1) for con-T in the absence of spermine. The added presence of a saturating amount of spermine (300 microM) resulted in an approximate 60% increase in the k(on) values for both con-G and con-T. These results demonstrate that con-T and con-G inhibit NMDA-evoked currents, as well as the potentiation by spermine, in what appears to be a noncompetitive manner, and that spermine increases the rate of conantokin inhibition.

The functional interactions of conantokins with anatomical sites in rat brain have been assessed through displacement of the non-competitive N-methyl-D-aspartate receptor (NMDAR) antagonist, dizocilpine (MK801). The binding of (+)-3-[125I]-iodo-MK801 (1 nM) to coronal sections from adult rat brain was inhibited in a dose-dependent manner by conantokin-T (con-T) and conantokin-G (con-G). Quantitative densitometry was used to determine IC50 values for conantokin inhibition of [125I]-MK801 binding in the cortex, thalamus and hippocampus. Con-T completely inhibited [125I]-MK801 specific binding in all brain regions at a saturating concentration of 100 microM. Con-G was able to completely displace [125I]-MK801 in the cortex and thalamus, but only inhibited this same binding up to approximately 90% in the hippocampus. Both peptides maintained their inhibitory properties in the presence of 1 mM EDTA, suggesting that divalent cations are not required for their action in this regard. The added presence of spermine (150 microM) resulted in a two-fold increase in [125I]-MK801 binding and a two-fold decrease in the IC50 values for both peptides. The data obtained in this investigation further demonstrate that [125I]-MK801 is a useful probe for the indirect determination of functional NMDAR ligand binding sites in rat brain sections.

The Antiarrhythmics Versus Implantable Defibrillators (AVID) trial is a prospective, randomized study of treatment for life-threatening ventricular arrhythmias. Patients who are eligible for the main trial but who are not enrolled for any reason are followed in a registry. The objective of the present study was to determine whether there are identifiable patient characteristics among these registry patients that may influence whether a patient is treated with an implantable defibrillator. The 914 patients in the registry were divided into 2 groups according to whether the primary treatment was an implantable defibrillator. The mean age of defibrillator patients was 60 years, compared with 65 years in the nondefibrillator group (p <0.001). Only 11.2% of defibrillator recipients were minorities, whereas the percentage of minorities in the nondefibrillator group was 18.7% (p <0.003). A history of recurrent ventricular fibrillation was more likely in the group treated with defibrillators (8.9% vs 4.4%, p <0.01), whereas a history of atrial fibrillation or diabetes mellitus were both significantly more likely in the nondefibrillator group. Among defibrillator patients, a higher proportion had ventricular fibrillation as the index arrhythmia; patients with ventricular tachycardia were significantly more likely to be treated without devices. In this prospective but nonrandomized cohort of patients treated for life-threatening ventricular arrhythmias, older age, minority status, and comorbidity reduced the chances that a patient would be treated with a defibrillator.

A rigorous, unannounced, campus-wide survey for removable surface contamination was performed at our institution. Wipe samples (n = 1,090) were collected from a variety of standardized locations in 45 large biomedical research laboratories that routinely use kBq-MBq (microCi-mCi) amounts of 3H, 14C, 32P, 35S, 51Cr, and 125I. The results showed a log-normal distribution for contamination, with about 90% of all samples below ten times background. Although working surfaces and equipment used in these laboratories can become contaminated with radioactive materials, especially by transfer from soiled gloves, the magnitude of the contamination is very small and typically restricted to surfaces, instruments, and equipment that are directly handled in the course of experimental work and which can be reasonably anticipated to be contaminated. These data suggest that contamination is not a significant problem in biomedical research laboratories at this institution and that the best protection from workplace contamination appears to continue to be the use of well-reviewed standard operating procedures and good work practices.

Animal perfusion is a common technique in the physiology research laboratory and typically involves the use of aqueous formaldehyde. Depending on the specific procedure conducted, the animal studied, and availability and efficiency of local ventilation systems, these procedures may create occupational over-exposure to formaldehyde, a regulated carcinogen. We report the design and performance of a local exhaust hood specifically developed for primate and small mammal perfusion. The hood facilitates this and other related procedures, while providing laboratory workers with a high degree of protection against exposure to formaldehyde and an inherent barrier against spills or splashes of potentially infectious material.

Uncoated metallic lead is widely used as radiation shielding in research and development, nuclear medicine and radiology, and various manufacturing processes. The common use of lead shielding, however, may present an insidious health hazard due to lead dust. Field and laboratory measurements were collected to evaluate the distribution and removal of lead from radiation shielding material as well as to measure airborne exposures during large shielding emplacement projects. The data indicate that lead is readily dispersed from visibly oxidized as well as freshly-cleaned shielding, but that a single coating of polyurethane can reduce lead removal by nearly three orders of magnitude. Although 8-hour time-weighted average exposures for workers constructing lead shielding structures were nearly all below the Occupational Safety and Health Administration's action level of 30 micrograms/m3 (due to short work periods), the distribution of airborne lead concentrations during this kind of work demonstrates a potential for overexposure.

We have determined that expression of the c-myb proto-oncogene is associated with estrogen receptor (ER) status and not with tumor progression in human breast epithelial cells. Analysis of normal, immortalized, nontumorigenic, and tumorigenic mammary epithelial cells showed that only ER+ tumor cell lines expressed readily detectable levels of c-myb mRNA and a Mr 75,000 protein that was the same size as the c-myb transcripts and protein products present in hematopoietic cells. In this report we show that c-myb mRNA and protein levels are down-regulated during estrogen withdrawal. A 20-fold increase in c-myb mRNA and protein expression was observed upon addition of beta-estradiol to the culture medium. Nuclear run-on transcription analyses showed that c-myb was transcribed at the same rate in the presence and absence of estrogen, suggesting that c-myb mRNA accumulation was regulated at a posttranscriptional level. To provide additional evidence that c-myb mRNA was dependent on ER expression, we examined c-myb mRNA levels in MCF-7 cells selected for resistance to antineoplastic drugs. c-myb expression was decreased only in cell lines that showed concomitant loss of ER expression. Moreover, c-myb mRNA was expressed and modulated by estrogen in ER-, MDA-MB-231 cells stably transfected with a human ER gene. When considered together, these data indicate that c-myb mRNA levels are regulated by estrogens and further suggest that this proto-oncogene plays a role in the biology of ER+ breast tumor cells.

The MDM2 gene is a nuclear phosphoprotein that is regulated by p53 and functions, in one capacity, to inhibit the transcriptional activity of the wild-type p53 protein. Multiple MDM2 transcripts were detected in human breast epithelial cells. In estrogen receptor-negative normal, immortal, and tumorigenic breast epithelial cells, we found a good correlation between MDM2 mRNA levels and expression of wild-type p53. When wild-type p53 was overexpressed in estrogen receptor-negative tumor cells containing a mutant or no endogenous p53, MDM2 mRNA levels increased significantly, indicating that wild-type p53 positively influences MDM2 mRNA levels in these tumor cells. Because all estrogen receptor-positive breast tumor cells had high MDM2 mRNA levels regardless of the status of their endogenous p53 protein, other factors likely influence MDM2 expression in these cells. Distinct MDM2 proteins (range, Mr 54,000-68,000 and 90,000-100,000, respectively) were differentially expressed in human breast epithelial cells. The lower molecular weight MDM2 proteins were most abundant in the normal mammary cells but present at varying levels in many of the tumor cells examined. MDM2 was a nuclear protein; however, nuclear staining intensity did not always correlate with the amount of MDM2-immunoreactive protein as determined by Western blot analysis. This discrepancy suggests that MDM2 interacts with novel cellular proteins in different kinds of breast epithelial cells.

The ESVEM Trial was a randomized prospective study to compare the predictive accuracy of electrophysiologic testing (EPS) to ambulatory electrocardiographic monitoring (Holter monitoring--HM) for long-term drug therapy of sustained ventricular tachyarrhythmias. 486 patients with documented ventricular tachycardia or resuscitated sudden death were randomized to EPS (n = 242) or HM (n = 244) and underwent serial drug testing with up to six antiarrhythmics; in the EPS limb a drug efficacy prediction was achieved in 108 patients (45%), compared to 188 (77%) in the HM limb (P < 0.001). Efficacy predictions were most frequent with sotalol therapy. During long-term follow-up of the 296 patients discharged on a drug predicted to be effective, there were 151 recurrences of an arrhythmic event; there were no differences in actuarial rates of arrhythmia recurrence between EPS and HM. With multivariate testing of 14 variables, only sotalol therapy and absence of prior antiarrhythmic therapy were associated with a significant reduction in risk of arrhythmia recurrence.

Although surveying for radioactive contamination by wiping surfaces is the norm, this practice can be highly variable and may be inefficient for detecting low-energy beta emitters. Relying on wipe testing may likewise be an inefficient use of personnel and may seriously underrepresent the amount of contamination present. In general practice, it is better to clean and, where applicable, renew surfaces regularly as part of standard operating protocols and work practices.

Mixed radioactive and chemical wastes generated by biomedical research were characterized, and various treatment methods for reducing their volume were evaluated. These wastes consist primarily of organic solvents used in the extraction and purification of radiolabeled biomolecules that are contaminated with low levels of the long-lived radionuclides, 3H and 14C. The Rockefeller University's mixed wastes fall into three broad chemical categories: phenol/chloroform, acetonitrile/water, and mixtures of miscellaneous solvents such as carbon tetrachloride, benzene, and other hazardous chemicals. Currently, with the exception of liquid scintillation cocktails (deregulated in 1981), there are no commercial disposal outlets for mixed wastes nor may they be stored legally for more than 90-180 d. Most of these mixed wastes can be effectively rendered into nonradioactive chemical and aqueous radioactive waste, both of which can be disposed of in accordance with existing regulations. However, to do so requires a Resource Conservation and Recovery Act (RCRA) Part B permit for licensure as a treatment, storage, and disposal facility. For many university research facilities, this may require financial and personnel resources disproportionate to the small amounts of waste produced. Also, such treatment, if not done properly, presents potential occupational hazards from the direct handling of waste materials. Deregulation of certain mixed wastes would be the safest, most cost-effective, and practical method for dealing with many mixed wastes of biomedical origin. In any event, a national regulatory solution must be found.

Dietary salt restriction is the most common therapeutic recommendation given to hypertensives, but past studies have assessed the effect of salt restriction using resting blood pressure (BP) measurements not with the newer technique of 24-h ambulatory BP monitoring. We compared the effect of high (250 mEq Na/day) and low (10 mEq Na/day) salt diets on resting versus ambulatory BP in 12 normal and 15 hypertensive subjects. Each diet was given for 7 days. Ambulatory BP was monitored from day 6 to day 7 of each diet; resting supine BP was measured on the morning of day 8. In normal subjects, neither resting nor ambulatory BP changed with sodium restriction. In hypertensives, resting BP fell 14 +/- 3/6 +/- 2 mm Hg (systolic/diastolic; P less than .01 for both) with sodium restriction while ambulatory BP fell only 4 +/- 2/2 +/- 2 (P = NS). The resting BP fall was significantly greater than the ambulatory BP fall (P less than .05) for both systolic and diastolic pressure. Ambulatory heart rates were also significantly greater during sodium restriction, suggesting that the low salt diet activated the sympathetic nervous system. This may, in turn, have partially offset the hypotensive effect of sodium restriction. We conclude that using resting BP to assess the effect of sodium restriction may overestimate the efficacy of this therapy. Ambulatory BP monitoring should be employed in future studies of sodium restriction.

Examination gloves worn for protection from biohazards were sampled and evaluated for their ability to exclude virus particles. We found that thin gloves manufactured from polyethylene or polyvinyl chloride are ineffective barriers while gloves of thin latex are superior but not without failure. Polyethylene and polyvinyl chloride gloves had failure rates of 40% and 22%, respectively. Following exposure to the common disinfectant, 70% ethanol, these failure rates increased to 94% and 56% for polyethylene and polyvinyl chloride gloves, respectively. Latex, although permeable to ethanol, was penetrated by virus less than 1% of the time regardless of whether the latex had been pre-exposed to disinfectant or not. This study highlights the need for caution on the part of those who rely upon examination gloves for protection from infectious agents as well as the need for establishing more adequate standards and testing procedures for their manufacture.

Frequency and grade of ventricular arrhythmias in patients with isolated aortic stenosis (AS) or regurgitation (AR) were determined by 24-hour ambulatory electrocardiographic monitoring. The occurrence of ventricular arrhythmias in patients with aortic valve disease was compared with that in matched control subjects without aortic valve disease. Complex arrhythmias were significantly more prevalent in patients with valve disease than in control subjects (40 of 102 vs 19 of 102); the significant difference occurred in patients without concomitant coronary artery disease (CAD). In patients with valve disease without CAD, complex arrhythmias were significantly more common than in normal control subjects (22 of 65 vs 4 of 64); in the presence of CAD, complex arrhythmias were as prevalent in those with aortic valve disease as in those without it (18 of 37 vs 15 of 37, respectively). Among patients with AS or AR, arrhythmia occurrence and grade of ventricular ectopic activity were not related to the degree of AS or AR, ventricular hemodynamics or the presence or absence of concomitant CAD.

We report a patient who developed pulmonary hypertension following repeated intravenous injection of dissolved pentazocine tablets. Through analysis of lung biopsy material, this was shown to be due to embolization of the cellulose filler in the tablet and the tissue reaction it produced. Administration of prednisone appeared to improve the patient's clinical state.

To evaluate systemic nitroglycerin (NTG) effects on reduced perfusion of ischemic myocardium in coronary disease, intravenous NTG actions on coronary circulatory dynamics were directly assessed intraoperatively during aortocoronary bypass surgery in 24 patients. Thus metered antegrade blood flow was measured through 56 separate intack saphenous vein bypass grafts to analyze NTG perfusion response in the obstructed native coronary artery (CA). In 34 bypassed CA with proximal luminal diameter narrowing greater than 50% to 90%, NTG reduced (p less than 0.01) graft flow (GF) 82 to 63 cc/min, thereby indicating that NTG dilated proximal stenoses with resultant increased CA flow. In 11 bypassed CA obstructed greater than 90% to 100% with well developed collaterals distally, NTG decreased (p less than 0.05) GF 64 to 53 cc/min, thus indicating enhanced collateral flow. In contrast, in 11 bypassed CA obstructions greater than 90% to 100% without collaterals, that NTG increased (p less than 0.02) GF 91 to 100 cc/min indicated NTG nonresponsiveness of the severely diseased CA. Thus systemic NTG improves perfusion to ischemic myocardium subserved by diseased coronaries with less than 90% stenosis or by greater than 90% obstructed vessels with substantial collaterals distally.

This study assessed the effect of low (40 mg) and high (324 mg) single dose aspirin on cardiac release of thromboxane A2 and prostacyclin as assessed by measurement of coronary sinus levels of metabolites in patients with coronary artery disease. Measurements were done in the resting state and in the presence of pacing stress prior to and 24 h after aspirin administration. There was no consistent response in prostaglandin release under conditions of tachycardia stress as compared to control. Following both doses of aspirin, thromboxane could not be detected at rest or with pacing, and prostacyclin metabolic levels were undetectable in six of seven patients. Prostaglandin levels were not related to myocardial lactate extraction or production and lactate levels had no consistent relationship to aspirin administration. These data indicate that both low and high doses of aspirin inhibit both thromboxane A2 and prostacyclin production in humans. Selective thromboxane inhibition might not be possible.

This study evaluates acute and chronic therapy with cibenzoline, a new class I antiarrhythmic drug, in 49 patients with ventricular arrhythmias. Acute therapy with 260 to 330 mg/day of cibenzoline resulted in a significant reduction in the number of hourly ventricular premature complexes (VPCs) (from 377 +/- 60 to 116 +/- 33, p less than 0.001), total paired VPCs in 24 hours (from 531 +/- 196 to 101 +/- 66, p less than 0.02), and total episodes of ventricular tachycardia in 24 hours (from 31 +/- 10 to 4 +/- 3, p less than 0.01). Among this group, acute therapy resulted in more than 75% suppression of VPC frequency in 29 of 49 patients, more than 90% suppression of paired VPCs in 31 of 42 patients, and complete suppression of ventricular tachycardia in 21 of 27 patients. Radionuclide evaluation of ventricular function revealed no deleterious effect of cibenzoline on ventricular function. Significant suppression of VPC frequency was maintained during 6 months of therapy in 16 of 19 patients and during 12 months of therapy in 9 of 10 patients. Trough plasma cibenzoline levels were measured during the acute dosing period. These levels did not differ among the group of responders (326 +/- 140 ng/ml) compared with nonresponders (354 +/- 282 mg/ml). Cibenzoline therapy resulted in adverse effects 18 patients and necessitated discontinuing therapy in 12. No patient had a proarrhythmic effect. In conclusion, cibenzoline appears to be as efficacious as the available antiarrhythmic drugs in treating chronic complex ventricular arrhythmias. Drug-related adverse effects occur with a frequency similar to that of other antiarrhythmic drugs.

We compared the antihypertensive effects of the beta-blocker atenolol and the converting enzyme inhibitor lisinopril during 12 weeks of treatment in patients with mild to moderate essential hypertension. Atenolol (n = 10) significantly decreased conventionally measured blood pressure from 144/103 to 135/93 mm Hg and lisinopril (n = 9) from 150/104 to 130/92 mm Hg. Based on data derived from automated 24-h ambulatory blood pressure monitoring, atenolol decreased the average whole-day systolic pressure by 18 +/- 6 mm Hg (p less than 0.02) and the diastolic pressure by 11 +/- 2 mm Hg (p less than 0.01). Lisinopril produced decreases of 27 +/- 5 mm Hg (p less than 0.01) and 13 +/- 2 mm Hg (p less than 0.001). Examination of the 24-h blood pressure patterns showed that the efficacies of the two drugs were similar. Each appeared to be effective throughout the whole-day monitoring period, although only lisinopril significantly decreased blood pressure during the final four-h period (4 AM to 8 AM) preceding the next day's dose. Neither drug produced significant echocardiographic changes in left ventricular wall thickness or muscle mass during the short-term treatment. Lisinopril and atenolol effectively decrease blood pressure during a 24-h period. Moreover, we found that automated whole-day blood pressure monitoring is a useful tool for comparing the efficacy and duration of action of differing antihypertensive agents.

Two cases of ventricular septal rupture complicating infero-posterior myocardial infarction which are atypical in presentation, clinical course, and outcome are presented and the relevant literature is reviewed. The patients presented late after the acute onset of congestive heart failure, without a history of chest pain, were diagnosed noninvasively, survived with medical therapy for 2 and 4 months, and went on to successful surgical repair.

Indomethacin (50 mg every eight hours) was given to 17 selected patients with pleurisy to control pain. Eleven of 17 obtained good to excellent relief of pain within 24 hours. Pain was not relieved in three patients and was only partly relieved in three others. Potentially serious side effects developed in two patients but resolved quickly. In selected patients indomethacin appears to be a reasonable initial choice for relief of pleural pain.

Many factors appear to influence diastolic left ventricular (LV) filling, including age, hypertension, and myocardial and coronary disease. Doppler-echocardiography was used to asses the influences of blood pressure (BP) on LV filling in 43 normotensive volunteers aged 12 +/- 0.98 years with heart rates less than or equal to 90 beats/min. Doppler peak diastolic transmitral flow velocities, diastolic flow integrals, and early diastolic deceleration were measured. An interesting difference was noted between the influence of systolic and diastolic BP. Systolic BP was related to LV mass (r = 0.43; P less than 0.005), but was unrelated to any of the Doppler filling indices. Diastolic BP was unrelated to LV mass, but was inversely related to peak early diastolic flow velocity (r = -0.37; P less than 0.05), early diastolic flow velocity integral (r = -0.34; P less than 0.05). The ratio of late-to-early filling (A/E) was directly related to diastolic BP (r = 0.42; P less than 0.005). The relationship between A/E and diastolic BP was strong in subjects (n = 21) with bimodal P waves in electrocardiogram (ECG) lead V1 (r = 0.61; P less than 0.005), but absent in those (n = 15) with unimodal P waves (r = 0.18; P = NS). Thus, the pattern of LV filling is related to the level of diastolic BP in normal adolescents, especially in those with bimodal P waves on ECG. These diastolic BP related changes are independent of heart rate and LV hypertrophy and may represent very early pre-hypertensive alterations in LV diastolic function.

This study employed 24-hour automated ambulatory blood pressure monitoring to evaluate whole-day patterns of blood pressure in age-matched groups of normotensive volunteers, untreated hypertensive patients, and hypertensive patients treated with prazosin. As would be expected, overall systolic and diastolic blood pressures were found to be lowest in the normotensive subjects and highest in the untreated hypertensive patients. The systolic and diastolic blood pressure values for patients receiving prazosin twice daily were significantly lower than in the untreated patients; they were slightly, but not significantly, higher than the values recorded for the normotensive volunteers. The data from 24-hour monitoring revealed no between-group differences in the actual circadian rhythm of the blood pressure. This finding established that the blood pressure pattern for hypertensive patients treated with prazosin was parallel to that for normal individuals. Thus, prazosin administered twice daily reduces blood pressure throughout a full 24-hour period in a fashion that maintains the normal circadian pattern of the blood pressure.

Forty patients with coronary artery disease and nonsustained ventricular tachycardia on ambulatory electrocardiographic monitoring underwent programmed electrical stimulation. In 22 patients, monomorphic ventricular tachycardia was induced at baseline drug-free electrophysiologic testing; 9 of these patients subsequently developed a clinical sustained ventricular tachyarrhythmia. In 18 patients, no tachycardia could be induced, and none of these 18 had subsequent tachycardia. In 25 of the 40 patients, arrhythmia management was guided by the results of electrophysiologic testing; this group included 11 patients who received antiarrhythmic therapy for induced ventricular tachycardia and 14 patients without inducible ventricular tachycardia who did not receive antiarrhythmic therapy. In the remaining 15 patients, arrhythmia management was not based on the results of electrophysiologic testing. Only two episodes of clinical sustained tachyarrhythmia occurred in the group receiving electrophysiologically guided therapy compared with seven episodes in the group treated without electrophysiologic guidance (p less than 0.01). Thus, in patients with coronary artery disease with nonsustained ventricular tachycardia on ambulatory electrocardiography, electrophysiologic testing can identify those at high and low risk for subsequent clinical tachycardia events. Furthermore, results of such testing can be used to optimize arrhythmia management in these patients.

Metastasizing squamous cell carcinoma of the lung developed in a patient who had juvenile papillomatosis but had had no previous radiation therapy. At the same time, a significant upper airway obstruction was present. All endobronchial lesions rapidly resolved with radiation therapy, and the carcinoma was resected.