HLA polymorphism in the Havasupai: evidence for balancing selection

The characterization and analysis of genetic variation at the HLA loci provides important insight for population geneticists trying to understand the evolutionary forces that have shaped human populations. This study describes the HLA-A and HLA-B loci serotyping and statistical analysis on an isolated Native American population, the Havasupai of Arizona. Four alleles at the HLA-A locus were identified, while eight alleles were found at the HLA-B locus. These variants were present as 20 of 32 potential two-locus haplotypes, with five of the six most common haplotypes exhibiting high positive linkage disequilibrium. Significant homozygote deficiency (heterozygosity excess) was detected both at HLA-A and at HLA-B. This deviation from Hardy-Weinberg proportions was not attributable to nonselective causes such as different allele frequencies in males and females or avoidance of consanguineous matings. In addition, the distribution of alleles at both HLA-A and HLA-B was more even than expected from neutrality theory; that is, the observed Hardy-Weinberg homozygosity was only 62.4% of that expected under neutrality. These observations suggest that balancing selection is of major importance in maintaining genetic variation at HLA-A and HLA-B.

Synaptically triggered action potentials in dendrites

We tested the hypothesis that action potentials originate in apical dendrites of pyramidal cells. Layer V somata were voltage clamped in thin slices of rat motor cortex. Fibers synapsing in unclamped regions far out on the apical dendrite caused small, slow synaptic currents, as recorded at the soma, and sometimes elicited complex, multicomponent current spikes, beginning with a small first spike. Hyperpolarization, or tetrodotoxin applied to basal dendrites and soma, blocked the later spike components without affecting the synaptic current and the first component, which was a synaptically triggered Na+ spike in the apical dendrite. Similar spikes followed voltage steps or direct stimulation. We conclude that Na+ action potentials are initiated in the apical dendrite in response to synaptic input.

Follow-up of a cohort of men with untreated benign prostatic hyperplasia

A cohort of 266 men with untreated benign prostatic hyperplasia (BPH) identified in a community-based survey were followed for a period of 1 year. Although the overall prevalence of urinary symptoms increased during the year, substantial within-subject variation in urinary symptomatology occurred, with up to a quarter of men reporting urgency and dribbling to have improved whilst one third of men reported other urinary symptoms to have deteriorated. Levels of bothersomeness caused by urinary symptoms did not show much change during the period of follow-up. An overall increase of 19% in urinary peak flow which was also consistent across all age groups was present at 1 year compared with baseline, even after adjusting for increased urinary void volume. A slow progression in the extent to which interference with selected activities of daily living by urinary dysfunction occurred. This was greater in men of working age (40-64 years), compared with men of retirement age (65-79 years). A longer period of observation is required in order to determine the extent to which a consistent pattern of urinary symptomatology exists in untreated BPH, as well as whether interference with daily living activities continues to progress over time.

Affected paroxysmal nocturnal hemoglobinuria T lymphocytes harbor a common defect in assembly of N-acetyl-D-glucosamine inositol phospholipid corresponding to that in class A Thy-1- murine lymphoma mutants

Deficient expression of glycoinositol phospholipid (GPI) anchored proteins in affected paroxysmal nocturnal hemoglobinuria (PNH) cells has been traced to a defect in GPI anchor assembly. In a previous study (Schubert, J., Schmidt, R. E., and Medof, M. E. (1993) J. Biol. Chem., in press) we characterized the biosynthesis of putative Man-containing GPI anchor precursors in normal peripheral blood lymphocytes and investigated assembly of these intracellular GPI intermediates in CD48- affected and CD48+ unaffected T and natural killer cell lines of PNH patients. We found that affected T cells from five patients exhibited a uniform defect in which dolichol-phosphoryl-Man was synthesized but no GPI mannolipids were expressed. In this study, membranes of patients' affected T cells were labeled with UDP-[3H]GlcNAc to evaluate earlier steps in GPI synthesis, and intact cells were fused to Thy-1- murine lymphoma mutants harboring different defects in early GPI assembly to test for the presence of corresponding or complementary lesions. In all cases, affected cell membranes failed to assemble GlcNAc-inositol phospholipid, the initial precursor of GPI anchor structures, and the intact cells failed to complement class A mutants while complementing other classes. Affected polymorphonuclear leukocytes from three additional patients of different origin were then labeled with [3H]Man and the labeling patterns found to correspond to those obtained with the T lymphocytes. Taken together the data indicate that the genetic lesion in PNH cells resides in a DNA element which: 1) encodes a product required for the synthesis of GlcNAc-inositol phospholipid, 2) corresponds to that altered in class A Thy-1- murine lymphoma mutants, and 3) is commonly affected in different patients.

Clinical audit in intensive care--the Meath Intensive Care Audit

Audit is now recognised as being an essential component of clinical practice. We report on the first year of the Meath Intensive Care Audit (MICA). This audit was instituted to investigate the activity of the unit, to assess the feasibility of continuous audit in our ICU and to provide data for future development of ICU facilities. Two hundred and fifty four patients were admitted between July 1st 1990 and June 30th 1991. The mean age at admission was 58 years and the mean length of stay 5.2 days. The mean APACHE II score was 16. Thirty four patients (13.4%) died in the ICU and 17 patients died in hospital following discharge from the unit bringing the hospital mortality rate to 20%. The audit proved feasible to implement and data collection is now accepted as a routine part of our ICU work.

Use of provincial health insurance plan billing data to estimate carpal tunnel syndrome morbidity and surgery rates

Following a work refusal at a plant manufacturing ice cream novelties in Ontario, we were asked to document cases of cumulative trauma disorders (CTDs) and carpal tunnel syndrome (CTS) in this workplace. There were 17 employees with possible hand and wrist problems identified from Workers Compensation Board (WCB) Forms, and from a list prepared at the time of the refusal. After obtaining consents, confirmations of the diagnoses of CTDs, CTS, and of surgical procedures for CTS were obtained from the physicians involved. The relative risk for these disorders among plant employees was estimated in two ways: 1) the rate of CTS operations between 1979 and 1990 was compared to that in the general population using Ontario Health Insurance Plan (OHIP) data on physicians' billings for these operations; and 2) the frequency of WCB first payment claims for tendinitis and CTS during 1987 to 1989 at the plant was compared to that among the entire labor force of Ontario. CTDs had been diagnosed in all 17 workers: 9 had had operations for CTS, but one had had this operation prior to working at the plant. Compared to the remaining 8 workers who had CTS operations, an estimated 0.08 CTS operations would be expected among the 150 employees on the plant's seniority lists between 1979 and 1990, if the estimated rates in the general population were present at the plant, giving a Standardized Morbidity Ratio of 10.0 (95% confidence interval [CI] 4.3-19.7; one-sided p = 2.1 x 10(-6)). There were 6 WCB claims for tendinitis and CTS among plant employees during 1987 through 1989. This frequency was about 68 times that in the entire Ontario labor force (95% CI 24.7-150). This investigation has shown that CTDs, and particularly CTS, documented by medical records, have occurred at least 10 times more frequently than expected at this plant. Use of health insurance billing data to estimate CTS operation rates represents a simple method for estimating the burden of illness at the individual plant level due to CTS (at least for that portion proceeding to surgery), using an objective outcome that can be confirmed from medical records.

Interleukin-6 and renal cell cancer: production, regulation, and growth effects

Interleukin-6 (IL-6) is a recently characterized pleiotropic cytokine with antitumor activity. We investigated the production of IL-6 by renal cell cancer (RCC) and the growth effects of IL-6 on RCC. Using immunoperoxidase staining, cytoplasmic IL-6 was detected in four of four renal tumor lines and in tumor cells from freshly nephrectomized RCC. We found that IL-6 mRNA was expressed at basal culture conditions by seven of ten RCC tumor lines tested. Biologically active IL-6, as measured by the B9 assay, was produced by all ten RCC tumor lines. The addition of tumor necrosis factor alpha (TNF alpha) significantly augmented the expression of IL-6 mRNA in five RCC tumor lines (P less than 0.05). The combination of interferon gamma IFN gamma and TNF alpha further enhanced the augmented IL-6 mRNA accumulation seen with TNF alpha alone (P less than 0.05). TNF alpha also significantly stimulated the production of biologically active IL-6 (P less than 0.01). Furthermore, IFN gamma and TNF alpha were found to enhance IL-6 bioactivity synergistically (P less than 0.05). The growth effects of IL-6 on RCC were also investigated in two experimental systems: IL-6 was found to stimulate proliferative responses in six of six RCC tumor lines as measured by thymidine-uptake assays; however, only one of six tumor lines displayed an increase in proliferative response of greater than 21% (113%). The growth effect of IL-6 was further tested in clonogenic assays. One of the tumor lines tested displayed an enhanced growth response of up to 200%. We conclude that IL-6 is produced by RCC; this production is enhanced by TNF alpha with synergistic effects seen with IFN gamma at both mRNA and protein levels. In turn, IL-6 may have a modest stimulatory growth effect on certain RCC tumor lines.

Inheritance and expression of chimeric genes in the progeny of transgenic maize plants

We obtained transgenic maize plants by using high-velocity microprojectiles to transfer genes into embryongenic cells. Two selectable genes were used to confer resistance to either chlorsulfuron or phosphinothricin, and genes encoding either E. coli beta-glucuronidase or firefly luciferase were used as markers to provide convenient assays for transformation. When regenerated without selection, only two of the eight transformed embryogenic calli obtained produced transgenic maize plants. With selection, transgenic plants were obtained from three of the other eight calli. One of the two initial lines produced 15 fertile transgenic plants. The progeny of these plants contained and expressed the foreign genes. Luciferase expression could be visualized, in the presence of added luciferin, by overlaying leaf sections with color film.

Exercise capacity and quality of life in the treatment of heart failure

In a double-blind study comparing two active treatments (digoxin and xamoterol) and placebo in patients with heart failure, improvements in exercise capacity and quality of life were observed in all three groups, with no significant differences. The substantial benefits seen in the placebo group were probably the result of increased attention from the medical and research staff and suggest the therapeutic value of special heart failure clinics. The relationship between exercise and symptomatic/functional status has been unclear. We developed quantitative measures of quality-of-life variables and examined their relationship with exercise capacity. There were significant relationships between change in exercise duration and changes in breathlessness, tiredness, chest pain, walking difficulty, rate of walking, difficulty with daily tasks, speed of daily tasks, mood, and sleeping. This study confirms the validity of measuring change in exercise capacity and demonstrates that specific measurements of quality of life make an important contribution to the evaluation of the treatment of heart failure.

Endothelin is a potent constrictor of the lamb ductus arteriosus

Endothelin was tested on isolated ductus arteriosus preparations from mature fetal lambs. At low PO2 (18-24 Torr; 1 Torr = 133.3 Pa), the compound constricted the vessel dose-dependently over the range from about 10(-10) to 10(-7) M. The contraction was sustained and did not subside even after an extended period of washing. Endothelin was also effective on tissues (PO2,217-231 Torr; indomethacin, 2.8 X 10(-6) M) that had been completely relaxed with CO (CO/O2 ratio, 0.28). CO treatment interferes with a cytochrome P-450 mechanism, which is considered crucial for the contractile response of the vessel to oxygen. These findings are consistent with a role of endothelin in the closure of the ductus arteriosus at birth.

Monooxygenase-mediated metabolism and binding of ethylene thiourea to mouse liver microsomal protein

Ethylenethiourea (ETU), a metabolite and degradation product of the ethylenebisdithiocarbamate fungicides, is a substrate for the flavin-dependent monooxygenase (FMO), a microsomal NADPH requiring enzyme that can oxidize ETU, as well as for the cytochrome P-450 enzyme system. The present study shows that the mouse metabolises ETU preferentially via the FMO system. FMO activity decreases as male, but not female mice, increase in age to 30 weeks. This difference in activity is reflected in decreased overall metabolism of ETU and in a decreased FMO-mediated binding of radiolabelled ETU to mouse liver microsomal protein. The rapid metabolism of ETU by the FMO system may contribute to the lack of acute toxicity and teratogenicity exhibited by the mouse relative to the rat. However, the FMO-mediated binding of ETU metabolites to mouse liver protein is consistent with the chronic hepatotoxicity exhibited by ETU in this species.

Validation studies for brain blood flow assessment by radioxenon tomography

A tomographic technique has been used recently for cerebral blood flow measurements with inhaled radioxenon. Based on experiments in a specially developed dynamic phantom and on studies in primates in vivo, we have analyzed the validity of this method for measurements of both regional and total blood flow in the brain. We have also examined the errors introduced into flow computations as a function of changes in such parameters as: rate of xenon input, size of region of interest, magnitude of regional flow rates, and inter-regional flow differences. Our findings indicate a reasonable degree of accuracy for flow measurements in gray matter regions that are 3 cm in diameter or larger, while white matter blood flow is generally overestimated. The accuracy for regional flow assessments degrades as a function of: diminishing region size, increasing inter-regional flow differences, and flow rates in excess of 100 ml/100 g/min. Measurements for brain regions 2 cm or smaller in diameter can be in error by 25-50% as a result of partial volume averaging. Although the technique is not ideal for accurate flow measurements in small regions of the brain, it nevertheless provides a convenient means of assessing perfusion in major vascular territories of the brain in routine clinical applications.

Role of Enterobius vermicularis in the aetiology of appendicitis

An evaluation was made of the histological material obtained from all 1529 appendices removed during the last 5 years at Southmead Hospital, Bristol, in order to elucidate possible relationships between the incidence of Enterobius vermicularis and the origin of inflammation in the appendix. In total, 1419 appendices were removed as cases of clinical appendicitis and 110 in the course of another surgical procedure. E. vermicularis was identified in 2.7 per cent of patients with clinical appendicitis and was most commonly seen in appendices with either chronic inflammation or where the appendix was histologically normal. E. vermicularis was rarely associated with histological changes of acute appendicitis. No cases of E. vermicularis infestation occurred in appendices removed during the course of other surgical procedures. The results suggest that, although E. vermicularis may have a causal role in appendicular pain and chronic inflammation, it is rarely related to acute appendicitis.

Comparison of the efficacy of nicardipine, a new calcium channel blocker, with nifedipine in the treatment of mild to moderate essential hypertension

Thirty-nine patients with mild to moderate essential hypertension participated in a parallel, single-blind study comparing 6 weeks' treatment of nicardipine hydrochloride (90 mg/day) with nifedipine (40 mg/day). Nicardipine-treated patients commenced therapy with a significantly higher mean supine diastolic blood pressure than the nifedipine-treated patients. There was a statistically significant fall in blood pressure (systolic and diastolic) on both treatments at the 3 and 6 week follow-up visits. On adjusting the results for the baseline inequality, no statistically significant differences were found between treatment groups. Seven patients withdrew from nifedipine therapy and six patients withdrew from nicardipine therapy due to adverse events. The results show that nicardipine hydrochloride at 90 mg/day is an effective anti-hypertensive agent. The incidence and nature of adverse events were similar on the two treatments.

The induction of sensitivity to gibberellin in aleurone tissue of developing wheat grains : I. The effect of dehydration

Aleurone layers from immature developing wheat grains (Triticum aestivum L. cvs. Sappo. and Champlein), though normally insensitive, can be made to produce α-amylase in response to gibberellic acid by subjecting the grains to a period of enforced dehydration prior to introduction to the hormone. The change in sensitivity appears to depend upon the water content of the tissue, water levels of below approximately 25% being critical for the effect. Grain detachment or duration of drying apparently do not qualitatively influence the development of sensitivity to gibberellic acid. Enhanced sensitivity resulting from drying is not caused by changes in gibberellic acid uptake. A possible mechanism for the change in sensitivity of aleurone cells might be through structural alterations in cell membranes.

Spontaneous and chemically induced transformation of rat embryo cell cultures

The transformation of Wistar rat embryo cells in vitro has been studied in passaged cultures using two criteria for transformation: (1) the ability of cells to form colonies in soft agar and (2) the ability of cells to form tumours in young syngeneic animals. In general there was good correlation between the two criteria. Spontaneous transformation was observed in all untreated cultures by 44 weeks although, by not allowing the cells to become confluent, the tendency was for cultures to transform earlier (i.e. 15-21 weeks). It was noticeable that despite untreated cultures having been in vitro for different lengths of time, most cultures transformed after a similar number of passages (42-50). Treatment of the embryo cells with the alkylating agent nitrosomethylurea (NMU) or benzo(alpha)pyrene (BP) sometimes resulted in transformation after a shorter period in vitro than the controls (minimum 12 weeks) although some treated cultures took longer. Transformed cells produced transplantable fibrosarcomata in syngeneic hosts and those arising from NMU transformed cells were histologically different from those arising from spontaneously transformed cells. The significant of spontaneous transformation in in vitro rat cell transformation systems is discussed.

The pepsinogens of human gastric mucosa

Fundic mucosal pepsinogens reveal six major bands of protease activity on gel electrophoresis and four minor bands. Antral mucosa shows two major bands of activity; the four rapidly moving bands found in fundic mucosa are found in lesser activity in the antral mucosa. Duodenal mucosa shows only one slowly moving band of protease activity. There is a significant difference in the pepsinogen pattern when the uninvolved fundic mucosa of gastric ulcer patients is compared with that of cancer patients.A satisfactory method is described for separating the pepsinogens on column chromatography.