Minor structural differences in Boc-CCK-4 derivatives dictate affinity and selectivity for CCK-A and CCK-B receptors

We previously reported novel Boc-CCK-4 (Boc-Trp-Met-Asp-Phe-NH2) derivatives possessing the general structure Boc-Trp-Lys[N epsilon-CO-NH-(R-Ph)]-Asp-Phe-NH2 (Shiosaki et al. J. Med. Chem. 1991, 34, 2837-2842). In contrast to Boc-CCK-4, which is 70-fold selective for the CCK-B receptor, the modified lysine-bearing tetrapeptides were highly potent and selective full agonists at the CCK-A receptor. Further investigation of the structure-activity profile following modification of the substituted phenylurea moiety appended off the lysine revealed that moving certain substituents, e.g. nitro or acetyl, from the 2- or 3-position on the phenyl ring to the 4-position, a relatively minor and subtle structural modification within the tetrapeptide, resulted in loss of CCK-A receptor selectivity and development of a trend toward CCK-B selectivity. These tetrapeptides, e.g. Boc-Trp-Lys[N epsilon-CO-NH-(4-NO2-Ph)]-Asp-Phe-NH2 and Boc-Trp-Lys[N epsilon-CO-NH-(4-Ac-Ph)]-Asp-Phe-NH2, were full agonists relative to CCK-8 in stimulating intracellular calcium mobilization in a cell line that expresses the CCK-B receptor.

Accuracy of self-reported educational attainment among diverse patient populations: a preliminary investigation

Despite speculation concerning the accuracy of self-reported information, particularly from certain patient populations, many neuropsychologists continue to estimate premorbid intellectual functioning on the basis of self-reported educational attainment. This study examined 116 individuals with diverse diagnoses [i.e., alcoholism, posttraumatic stress disorder (PTSD), schizophrenia or schizoaffective, and dementia] to determine the accuracy of their self-reported high school educational attainment. Results suggest that at least half of all participants were inaccurate as defined by discrepancies between actual and estimated GPA greater than.5 on a traditional 4-point grading scale. Most patients were inaccurate in the direction of overestimating their educational attainment. Patients diagnosed with alcoholism and PTSD were significantly less accurate in recalling their educational history when compared to a group of normal-control subjects. Several subjects, whose records could not be verified, were found to have not attended high school as they had claimed. These results underscore the potential inaccuracy that exists when estimating premorbid intelligence using self-reported information.

Role of nitric oxide in modulating the long-term renal and hypertensive actions of norepinephrine

We have previously reported that nitric oxide (NO) plays an important role in protecting the renal vasculature from acute norepinephrine-induced vasoconstriction. The purpose of this study was to determine the importance of this interaction between NO and norepinephrine in long-term control of renal hemodynamics and arterial pressure. To achieve this goal, we examined the effects of an intrarenal infusion of norepinephrine (NE) (0.1 microgram.kg-1.min-1) for 7 days in conscious, chronically instrumented control dogs and in dogs pretreated with a synthesis inhibitor, L-NAME (3 micrograms.kg-1.min-1 intrarenally). Both groups of dogs also received captopril (15 micrograms.kg-1.min-1) plus angiotensin I] intravenously to clamp the renin-angiotensin system throughout the protocol. In control dogs (n = 6), intrarenal infusion of NE decreased renal plasma flow by 9% (134 +/- 10 to 122 +/- 14 mL/min) and glomerular filtration rate by 16% (49 +/- 4 to 41 +/- 5 mL/min) while having no effect on mean arterial pressure (100 +/- 3 to 98 +/- 4 mm Hg). In marked contrast, in dogs pretreated with intrarenal L-NAME (n = 9), NE decreased renal plasma flow by 37% (129 +/- 8 to 81 +/- 16 mL/min) and glomerular filtration rate by 32% (47 +/- 3 to 32 +/- 5 mL/min) while increasing mean arterial pressure from 104 +/- 5 to 113 +/- 6 mm Hg. The results of this study demonstrate that NO plays an important role in modulating the long-term actions of NE on renal function and arterial pressure.

Changes in diagnostic decision-making after a computerized decision support consultation based on perceptions of need and helpfulness: a preliminary report

We examined the degree to which attending physicians, residents, and medical students' stated desire for a consultation on difficult-to-diagnose patient cases is related to changes in their diagnostic judgments after a computer consultation, and whether, in fact, their perceptions of the usefulness of these consultations are related to these changes. The decision support system (DSS) used in this study was ILIAD (v4.2). Preliminary findings based on 16 subjects' (6 general internists, 4 second-year residents in internal medicine, and 6 fourth-year medical students) workup of 136 patient cases indicated no significant main effects for 1) level of experience, 2) whether or not subjects indicated they would seek a diagnostic consultation before using the DSS, or 3) whether or not they found the DSS consultation in fact to be helpful in arriving at a diagnosis (p > .49 in all instances). Nor were there any significant interactions. Findings were similar using subjects or cases as the unit of analysis. It is possible that what may appear to be counter-intuitive, and perhaps irrational, may not necessarily be so. We are currently examining potential explanatory hypotheses in our ongoing current, larger study.

A cereal centromeric sequence

We report the identification of a family of sequences located by in situ hybridisation to the centromeres of all the Triticeae chromosomes studied, including the supernumerary and midget chromosomes, the centromeres of all maize chromosomes and the heterochromatic regions of rice chromosomes. This family of sequences (CCS1), together with the cereal genome alignments, will allow the evolution of the cereal centromeres and their sites to be studied. The family of sequences also shows homology to the CENP-B box. The centromeres of the cereal species and the proteins that interact with them can now be characterised.

The development of the Functional Capacity Index

OBJECTIVE

This paper describes the development of the Functional Capacity Index (FCI) and compares it to the Abbreviated Injury Scale (AIS) and the Injury Impairment Scale (IIS).

METHODS

The FCI maps 1990 AIS injury descriptions into scores that reflect expected levels of reduced functional capacity at 1 year after injury. Its development involved three steps. First, an expert clinical panel identified 10 relevant dimensions of function and defined levels of capacity within each dimension. A group of 114 individuals then rated the relative severity of different levels of function in terms of their impact on daily living. The third step involved clinical experts assigning FCI scores to AIS '90 injury descriptions based on their knowledge of the likely 1-year consequences associated with each injury. As a first step in validating the FCI, 1 year postinjury levels of impairment (based on range of motion and strength) were correlated with FCI, IIS, and AIS scores derived for 301 patients with severe lower extremity fractures.

RESULTS

Consistency of FCI scores derived within and across dimensions of function argue for the conceptual integrity of the index. Non-zero FCI scores were assigned to only 26% of the 1,272 AIS injury descriptions, indicating that, for most of the injuries in the AIS dictionary, very little or no residual impairment is expected for the average person at 1 year. FCI scores derived for 301 patients with lower extremity fractures ranged from 0 to 63 (out of a possible 100 points). A modest correlation was found between FCI scores and actual levels of impairment observed at 1 year. Compared with the AIS and the IIS, the FCI appeared to discriminate somewhat better among different levels of function.

CONCLUSIONS

Although further empirical validation of the FCI is essential before it can be broadly applied, its development represents an important first step in the generation of an AIS-based measure of expected functional outcome. Its validation is encouraged across a variety of settings and injury types.

Irradiated uveal melanomas: cytopathologic correlation with prognosis

PURPOSE

We analyzed the additional prognostic information from cytopathologic data obtained at the time of uveal melanoma irradiation.

METHODS

Fine-needle aspiration biopsies (FNABs) were performed and reviewed in a masked manner. These data and standard prognostic variables were correlated with survival and local tumor recurrence using Kaplan-Meier and Cox model statistical techniques.

RESULTS

Cytopathologic assessment of cell type added to prognostic accuracy. In 116 patients, the percentage of epithelioid cells on FNAB and ciliary body involvement were most strongly correlated with melanoma-related mortality.

CONCLUSIONS

FNAB data improved our prognostic accuracy in irradiated uveal melanoma patients.

Renin regulation in cultured proximal tubular cells

Recent studies have documented the presence of a complete renin-angiotensin system in the proximal tubule of the kidney: however, little is known about the regulation of renin in this proximal tubular system. Therefore, we performed the present studies to learn whether the behavior of the renin system in cultured proximal tubule is similar to that of the juxtaglomerular renin system. Basal renin secretion from rabbit proximal tubular cells in primary culture was low and not affected by isoproterenol (10(-5) mol/L), diltiazem (10(-5) mol/L), or a zero-calcium bath (O nmol/L). Only the calcium ionophore A23187 (10(-4) mol/L) significantly reduced renin secretion in these cells (from 2.44 +/- 0.37 to 1.14 +/- O.08 ng angiotensin I/mg protein per hour, P<.05). When the proximal tubular cells were lysed so the effects of the test agents on intracellular renin content could be assessed, isoproterenol caused a significant twofold (107 percent) increase (from 2.02 +/- 0.56 to 4.18 +/- 0.81 ng angiotensin I/mg protein per hour, P<.05), whereas diltiazem, A23187, and zero- and high-calcium baths did not produce a significant change. The effects of these agents on renin mRNA were examined in rabbit and rat proximal tubular cells in primary culture with the use of an S1 nuclease protection assay. Densitometry analysis of renin mRNA and either GAPDH mRNA (rat) or alpha-actin (rabbit) showed no significant alterations in renin mRNA abundance. In summary, these results confirm the presence of renin mRNA in cultured proximal tubular cells and suggest that a low-level, constitutive secretion of renin occurs in this system that is decreased by A23187. Moreover, the results also suggest that proximal tubular renin is regulated, albeit differently from the juxtaglomerular renin system. Finally, short-term increments in proximal tubular renin occur without a change in renin mRNA.

The role of the four Ca2+ binding sites of troponin C in the regulation of skeletal muscle contraction

In order to study the role of the Ca2+-specific sites (I and II) and the high affinity Ca2+-Mg2+ sites (III and IV) of TnC in the regulation of muscle contraction, we have constructed four mutants and the wild type (WTnC) of chicken skeletal TnC, with inactivated Ca2+ binding sites I and II (TnC1,2-), site III (TnC3-), site IV (TnC4-), and sites III and IV (TnC3,4C-). All Ca2+ binding site mutations were generated by replacing the Asp at the X-coordinating position of the Ca2+ binding loop with Ala. The binding of these mutated proteins to TnC-depleted skinned skeletal muscle fibers was investigated as well as the rate of their dissociation from these fibers. The proteins were also tested for their ability to restore steady state force to TnC-depleted fibers. We found that although the NH2-terminal mutant of TnC (TnC1,2-) bound to the TnC-depleted fibers (with a lower affinity than wild type TnC (WTnC)), it was unable to reactivate Ca2+-dependent force. This supports earlier findings that the low affinity Ca2+ binding sites (I and II) in TnC are responsible for the Ca2+-dependent activation of skeletal muscle contraction. All three COOH-terminal mutants of TnC bound to the TnC-depleted fibers, had different rates of dissociation, and could restore steady state force to the level of unextracted fibers. Although both high affinity Ca2+ binding sites (III and IV) are important for binding to the fibers, site III appears to be the primary determinant for maintaining the structural stability of TnC in the thin filament. Moreover, our results suggest an interaction between the NH2- and COOH-terminal domains of TnC, since alteration of sites I and II lowers the binding affinity of TnC to the fibers, and mutations in sites III and IV affect the Ca2+ sensitivity of force development.

Apoptosis induced by tumor necrosis factor-alpha in rat hepatocyte cell lines expressing hepatitis B virus

Three well differentiated SV40-immortalized rat hepatocyte cell lines, CWSV1, CWSV2, and CWSV14, and Hepatitis B Virus (HBV)-producing cell lines derived from them were examined for sensitivity to tumor necrosis factor (TNF)-alpha. CWSV1, CWSV2, and CWSV14 cells were co-transfected with a DNA construct containing a dimer of the HBV genome and the neo gene and selected in G418 to generate stable cell lines. Characterization of these cell lines indicated that they contain integrated HBV DNA, contain low molecular weight HBV DNA compatible with the presence of HBV replication intermediates, express HBV transcripts, and produce HBV proteins. The viability of CWSV1, CWSV2, and CWSV2 cells was not significantly altered when they were treated with TNF-alpha at concentrations as high as 20,000 U/ml. The HBV-expressing CWSV1 cell line, SV1di36, and the HBV-expressing CWSV14 cell line, SV14di208, were also not killed when treated with TNF-alpha. However, the HBV-expressing CWSV2 cell line, SV2di366, was extensively killed when treated with TNF-alpha at concentrations ranging from 200 to 20,000 U/ml. Analysis of several different HBV-producing CWSV2 cell lines indicated that TNF-alpha killing depended upon the level of HBV expression. The TNF-alpha-induced cell killing in high HBV-producing CWSV2 cell lines was accompanied by the presence of an oligonucleosomal DNA ladder characteristic of apoptosis.

Effects of some components of the essential oil of chamomile, Chamomilla recutita, on histamine release from rat mast cells

The influence of three compounds of the essential oil of Chamomilla recutita (L.) Rauschert on the protamine sulphate-provoked degranulation of mast cells from Lewis-1a rats was investigated. The effect was determined by measuring histamine liberation fluorometrically. Chamazulene and (-)-alpha-bisabolol had no distinct effects. The en-yne dicycloether partly inhibited the degranulation in concentrations above 10(-4) M.

ABT-431: the diacetyl prodrug of A-86929, a potent and selective dopamine D1 receptor agonist: in vitro characterization and effects in animal models of Parkinson's disease

(-)-Trans 9,10-hydroxy-2-propyl-4,5,5a,6,7,11b-hexahydro-3-thia-5- azacyclopent-1-ena[c]phenanthrene hydrochloride (A-86929) is a potent and selective full agonist at the dopamine (DA) D1-like receptor. Judging by its binding affinities to the D1 and D2 classes of receptors, the compound is approximately 20-fold D1 receptor-selective, whereas relative potencies based on functional in vitro assays indicate that A-86929 is greater than 400-fold D1-selective. A-86929 has moderate to weak (Ki > 1 microM) affinity at other monoaminergic and peptidergic receptors, at ion channels and at monoamine uptake sites. The catechol of A-86929 was bis-acetylated to produce the prodrug, (-)-trans 9,10-acetoxy-2-propyl-4,5,5a,6,7,11-b-hexahydro-3-thia- 5-azacyclopent-1-ena[c]phenanthrene hydrochloride (ABT-431), which is more chemically stable yet is rapidly converted to the parent compound with a half-life of less than 1 min in plasma. Both A-86929 and ABT-431 produced contralateral rotation in rats bearing unilateral 6-hydroxydopamine lesions, with ED50 values of 0.24 mumol/kg s.c. and 0.54 mumol/kg s.c., respectively. A-86929 and ABT-431 improved behavioral disability scores and increased locomotor activity in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned marmoset model of Parkinson's disease in a dose-dependent manner (the minimum effective dose was 0.10 mumol/kg s.c.). When administered three times daily for 30 consecutive days to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-lesioned marmosets, A-86929 significantly improved disability scores throughout the duration of the study. Current Parkinson's disease therapy includes L-dopa, which stimulates both classes of DA receptors by virtue of its conversion to DA in vivo, and direct-acting D2-selective agonists. Stimulation of the D2 receptor, which is associated with all current DA agonist-based therapies, may contribute to their dose-limiting side effects. An agent such as A-86929 (or its prodrug ABT-431), which selectively stimulates the D1 receptor, may represent a novel mechanism for Parkinson's disease therapy with the potential for an improved side-effect profile and, consequently, improved patient compliance.

The influence of a decision support system on the differential diagnosis of medical practitioners at three levels of training

As computer-based diagnostic consultation systems become, available, their influence and usefulness need to be evaluated. This report, based on partial data from a larger study, examines the influence of Iliad, a diagnostic consultation system, on the differential diagnosis of fourth year medical students, residents in medicine, and attendings in general internal medicine. Our results show that when faced with difficult diagnostic cases, medical students add significantly more diagnoses from Iliad's differential than do residents or attendings. However, the quality of Iliad's diagnostic advice in terms of the presence of the correct diagnosis, is no better for consultations done by students or residents compared to attendings.

Effects of a decision support system on the diagnostic accuracy of users: a preliminary report

OBJECTIVES

To assess the effects of incomplete data upon the output of a computerized diagnostic decision support system (DSS), to assess the effects of using the system upon the diagnostic opinions of users, and to explore if these effects vary as a function of clinical experience.

DESIGN

Experimental pilot study. Four clusters of nine cases each were constructed and equated for case difficulty. Definitive findings were omitted from the case abstracts. Subjects were randomly assigned to one of four clusters and were trained on the DSS prior to use.

SUBJECTS

The study involved 16 physicians at three levels of clinical experience (six general internists, four residents in internal medicine, and six fourth-year medical students), from three academic medical centers.

PROCEDURE

Each subject worked up nine cases, first without and then with ILIAD consultation. They were asked to offer up to six potential diagnoses and to list up to three steps that should be the next items in the diagnostic workup. Effects of DSS consultation were measured by changes in the position of the correct diagnosis in the lists of differential diagnoses, pre- and post-consultation.

RESULTS

The DSS lists of diagnostic possibilities contained the correct diagnosis in 38% of cases, about midway between the levels of accuracy of residents and attending general internists. In over 70% of cases, the DSS output had no effect on the position of the correct diagnosis in the subjects' lists. The system's diagnostic accuracy was unaffected by the clinical experience of the users.

Bacterial peritonitis in continuous ambulatory peritoneal dialysis: effect on dialysis on host defense mechanisms

We have used an experimental model of continuous ambulatory peritoneal dialysis (CAPD) to investigate the effect of dialysis on host defense mechanisms in the peritoneal cavity. Laboratory rats undergoing regular dialysis were challenged with a single bolus of Staphylococcus epidermidis, Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa. Intraperitoneal challenges with all four microbial strains underwent a rapid clearance during the first 4 hours, irrespective of whether the host was undergoing dialysis. Studies using S epidermidis showed that the rapid clearance was not mediated by the diaphragmatic stomata as might have been expected. Dialysis did, however, cause delays over the following 48 hours with all of the pathogens except C albicans. Bacterial clearance over a 10-day period was strain dependant, and microbial persistence was related to adhesion formation around the cannula. Again C albicans was an exception. Our conclusions are that dialysis does not affect the innate defense mechanisms involved in the early clearance of a bolus challenge to the peritoneal cavity but can cause delays in eradicating microorganisms that survive this phase. Because these experiments were carried out using a bolus inoculum, it may be necessary to reevaluate the effect of dialysis on host defenses in the peritoneal cavity under conditions in which the challenge more closely approximates a touch contamination event.

Factors promoting completion of advance directives in the hospital

BACKGROUND

The 1991 Patient Self-Determination Act required health care providers to give patients information about advance directives.

OBJECTIVES

To investigate whether the requirement to distribute information to hospital patients increased completion of the health care proxy. To also explore factors that might influence use of advance directives, including demographic variables and methods of informing patients about the directives.

PATIENTS AND METHODS

We interviewed 419 randomly selected patients who were admitted for a planned admission to two tertiary care, teaching hospitals. Patients at one hospital received proxy information before the day of admission, at a pretesting visit, or by mail. The other hospital distributed the proxy information only on the day of admission.

RESULTS

Before receiving hospital materials, 17% of all patients had completed proxies. After receiving hospital proxy forms, an additional 40% completed proxies at the hospital that distributed forms before the day of admission. Only 4% of the patients completed proxies at the hospital that distributed information only on the day of admission. The most frequently cited barrier to completion of a proxy was not seeing the form. Few patients said they did not want to think about the subject.

CONCLUSIONS

Completion rates for advance directives may be markedly improved by altering the time for distributing information to patients admitted to the hospital for a planned admission. Patients were more likely to complete a proxy in the hospital that distributed the form in advance of the day of admission, a result that was unexplained by other variables in the study. Although many patients would prefer to receive information about advance directives during an office visit with a physician, hospitalization can provide a valuable opportunity for many patients to complete directives.

Surgical techniques for covering exposed roots

Each grafting technique described here produced successful root coverage. Predictable root coverage by use of current techniques has increased options for managing gingival recession and associated problems.

Accuracy of presumed uveal melanoma diagnosis before alternative therapy

AIMS/BACKGROUND

This study was performed to ascertain the diagnostic accuracy rate of non-invasive tests in patients with presumed uveal melanomas scheduled to be treated with either irradiation or cyclochoroidectomy.

METHODS

One hundred consecutive patients who had non-invasive tests followed by fine needle aspiration biopsy (FNAB) as prior alternative treatment were analysed retrospectively.

RESULTS

In 86 cases the diagnosis of uveal melanoma was confirmed on FNAB. In five cases false negative results were obtained. In nine patients a diagnosis other than a uveal melanoma was made on the basis of cytopathology. No significant morbidity and no evidence of tumour spread occurred.

CONCLUSION

In presumed uveal melanomas eligible for treatment with alternative therapies, the diagnostic accuracy of non-invasive tests is not as good as with larger tumours that require enucleation. Fine needle aspiration biopsy data resulted in correct management of 9% of cases that were thought to have uveal melanomas on non-invasive tests, but had other lesions on cytopathological evaluation.

The precision of practice analysis results in the professions

A practice analysis, in which an appropriate sample of professionals is asked to describe what they do in their practices, is considered an essential part of the content-related validity evidence for licensure and certification tests. This article examines the precision of estimates of the mean frequencies for categories of activities in an activity inventory administered on two occasions about 6 weeks apart. In particular, it explores the variability in estimates of the mean frequencies for categories due to the sampling of respondents, activity statements, and occasions. The results suggest that samples of 200 respondents, about 10 to 20 activity statements per category, and one occasion are adequate for estimating the mean frequency for each category.

Optical Properties of the South Pole Ice at Depths Between 0.8 and 1 Kilometer

The optical properties of the ice at the geographical South Pole have been investigated at depths between 0.8 and 1 kilometer. The absorption and scattering lengths of visible light ( approximately 515 nanometers) have been measured in situ with the use of the laser calibration setup of the Antarctic Muon and Neutrino Detector Array (AMANDA) neutrino detector. The ice is intrinsically extremely transparent. The measured absorption length is 59 +/- 3 meters, comparable with the quality of the ultrapure water used in the Irvine-Michigan-Brookhaven and Kamiokande proton-decay and neutrino experiments and more than twice as long as the best value reported for laboratory ice. Because of a residual density of air bubbles at these depths, the trajectories of photons in the medium are randomized. If the bubbles are assumed to be smooth and spherical, the average distance between collisions at a depth of 1 kilometer is about 25 centimeters. The measured inverse scattering length on bubbles decreases linearly with increasing depth in the volume of ice investigated.

Impact of parental smoking on the prevalence of wheezing respiratory illness in children

To quantitatively assess environmental tobacco smoke exposure from parental smoking as a risk factor for asthma or wheezing in childhood, and to derive estimates of excess asthma/wheezing lower respiratory tract illness cases attributable to this risk factor, a cross-sectional analysis of the 1987 National Medical Expenditure Survey (a national probability sample of the civilian, noninstitutionalized US population) was undertaken. The National Medical Expenditure Survey included 7,578 children and youth less than 18 years of age in a stratified cluster sampling of US households. After using logistic regression analysis to control for sex, race/ethnicity, region of residence, population density, poverty status, maternal educational level, family size, and father's current smoking status, children whose mothers smoked at the time of the survey were more likely than children of nonsmoking mothers to experience wheezing respiratory illness (odds ratio = 1.36, 95% confidence interval 1.14-1.62). The association was greatest among children less than 2 years of age. The authors' estimate of the attributable risk in the US population indicates that maternal smoking is responsible for approximately 380,000 excess cases of childhood asthma/wheezing lower respiratory tract illness or 7.5% of the total number of such symptomatic children.

Unreliability of the abdominal fat pad biopsy in the evaluation of nephrosis: report of 3 consecutive cases

In the workup of unexplained nephrotic syndrome in the elderly patient, renal biopsy has shown amyloidosis to be the cause in 15-30% of the cases. Most of the cases of amyloidosis are primary and are, therefore, treatable with alkylating agents, albeit at a high level of toxicity. Abdominal fad pad biopsy has been suggested as a minimally invasive, low-cost method for diagnosing amyloidosis that is 100% specific. We report our experience with 3 consecutive cases of fat pad biopsy in the workup of unexplained nephrosis in the elderly patient: including the first false positive reported with respect to nephrotic renal disease, a false negative, and a true positive. We feel that in an elderly patient with unexplained nephrosis though the abdominal fat pad biopsy may be helpful, the patient should not be committed to a regimen with potentially very high toxicity on the basis of a positive fat pad biopsy alone. We recommend that the more invasive renal biopsy be performed should therapy with alkylating agents be contemplated.

Independent and coordinate regulation of beta 1- and beta 2-adrenergic receptors in rat C6 glioma cells

Rat C6 glioma cells have both beta 1- and beta 2-adrenergic receptors in approximately 7:3 ratio. When the cells were exposed to the beta-adrenergic agonist isoproterenol, there was a rapid sequestration of up to 50% of the surface receptor population over a 30-min period as measured by the loss of binding of the hydrophilic ligand [3H] CGP-12177 to intact cells. Using the beta 1-selective antagonist CGP 20712A to quantify the proportion of the two subtypes, it was found that although both beta 1 and beta 2 receptors were sequestered, the latter were sequestered initially twice as fast as the former. More prolonged agonist exposure led to a down-regulation of approximately 90% of the total receptor population by 6 h as measured by the loss of binding of the more hydrophobic ligand [125I]iodocyanopindolol to cell lysates. The two subtypes, however, underwent down-regulation with similar kinetics. Treatment of the cells with agents that raise cyclic AMP levels such as cholera toxin and forskolin resulted in a slower, but still coordinated down-regulation of both subtypes. Thus, there appears to be both independent and coordinate regulation of endogenous beta 1-and beta 2-adrenergic receptors in the same cell line.

Toward a comprehensive biomechanical injury cost model

The proposed biomechanical injury cost model utilizes surrogate-based injury assessment functions to predict the probability of occurrence and the probable cost of specific injuries to the head, thorax, abdomen, and lower extremities. The resulting probability cost is a function of the number, location, and severity of injuries. As more precise injury assessment functions and more accurate cost estimates become available, the model will become an effective tool for comparing and classifying different injury patterns.

Cloning and sequence analysis of the spike gene from several feline coronaviruses

The DNA sequence encoding the spike gene from the DF2 strain of Type II feline infectious peritonitis virus (FIPV), a temperature sensitive FIPV virus (TS-DF2) and an isolate of feline enteric coronavirus (FECV 1683) were determined. Comparison of the published WSU 1146 and DF2 FIPV S genes showed that the viruses shared a high degree of homology (99.6%). Likewise, the S gene of the virulent DF2 FIPV virus was closely conserved to that isolated from the vaccine virus strain, TS-DF2 FIPV. In contrast, the FECV S gene had numerous DNA and amino acid differences when compared to the virulent FIPV sequences. Sequence differences among the feline coronavirus isolates were localized to the amino-terminus region of the S gene.