The silver impregnation method applied to the dentin matrix of rachitic rats and to that of rats with healing rickets.
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Animals↗
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Results for “Irving Method”
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Revising the British Occupational Hygiene Society asbestos standard: 1968-1982.
BACKGROUND: In 1968 the British Occupational Hygiene Society (BOHS) published a chrysotile asbestos hygiene standard. As a consequence of acknowledged inadequacies of the data, it underestimated the risks of exposure, but its influence was international and operated for longer than it merited. Five years later, BOHS reported the standard not to be in need of amending, despite its own doubts and no cognizance having been taken of the cancer hazard. Within months, stung by criticism from Dr. Irving J. Selikoff, industry required it to review the standard, which BOHS continued to do for a number of years before giving up. METHODS: Material obtained for the American Courts by means of legal discovery from an asbestos company's archive, provided information on the membership of the new BOHS committees, and on its operation. RESULTS: Alterations in the composition of the new committees included importantly the introduction of certain independent scientists, whose rigor militated against the ready production of a new hygiene standard acceptable to industry. CONCLUSIONS: There was a time in Britain when a learned society might with impunity omit to consult the views of workers or their representatives when making value judgments about their health and safety, but consider it proper to accede to industry's decision as to what hygiene standard it would accept. Health and Safety at Work legislation in 1974, established an organization on which industry and labor were represented, with the onus for recommending hygiene standards. For several years the BOHS Asbestos Sub-Committee continued attempting to reconcile the interests of industry, until finally abandoning hygiene standard setting as its mission.
Academies and Institutes↗
Comparison of the vaccine efficacy of gamma-irradiated Schistosoma japonicum cercariae with the defined antigen Sj62(IrV-5) in pigs.
Development of a vaccine against Schistosoma japonicum which can protect both man and the domestic animal zoonotic reservoirs of infection would be an invaluable tool in attempts to control this infection in those areas in which conventional control methods have failed to break transmission. The pig is a natural host of S. japonicum and because of its anatomical and immunological similarities to humans, it is a potentially valuable host for studies on S. japonicum in particular and schistosomes in general. Radiation-attenuated cercariae are highly effective in inducing immunity in experimental schistosomosis and there are promising reports of partial protection against schistosomes with recombinant-derived individual antigens. In the present study we have set out to establish a protocol for inducing protection with gamma-irradiated cercariae in pigs and to assess the protective capacity of recombinant and naked DNA formulations of Sj62, a 62kDa region of S. japonicum myosin. The corresponding S. mansoni version or Sj62, recombinant IrV-5, has previously been implicated in irradiated vaccine immunity in S. mansoni infections and has been shown to induce high levels of immunity in a variety of hosts. Groups of pigs were immunised three times at 2-week intervals with 2000 cercariae irradiated at 20krad, with Sj62 as a recombinant (rSj62) incorporated in Freund's adjuvant, a micellar preparation, or as a naked DNA construct. Vaccination with irradiated cercariae did not induce significant anti-Sj62 antibody but following intramuscular challenge with 2000 cercariae, the vaccinated pigs showed >95% resistance as assessed by reduced faecal egg output, worm tissue egg burdens and also reduced septal fibrosis. Immunisation with each of the Sj62 formulations induced significant anti-Sj62 antibody responses, the highest titre (>12,800) being with the Freund's preparation but none of the Sj62-immunised groups showed significant resistance to challenge. The data suggest that Sj62 shows little promise as a vaccine candidate for schistosomosis.
Animals↗
The effect of enzyme treatment upon the resorption of scapular implants.
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Animals↗
Isolation of deoxyribonucleic acid and ribosomal ribonucleic acid from rat liver.
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Animals↗
Which nutritional measurements assess protein-energy nutritional status in patients receiving home parenteral nutrition?
Weight, midarm circumference, triceps skinfold thickness, arm muscle circumference, albumin, prealbumin, transferrin and total lymphocyte count were measured at each outpatient visit in patients reveiving home parenteral nutrition from September 1987 to November 1991. Each nutritional variable was analysed for individuals and for the whole group. Group data were expressed using the actual values obtained and successive differences (the change between clinic attendances). Nutritional variables were evaluated using a correlation matrix. Identical analysis of individual and group data demonstrates that laboratory investigations are of little value in the assessment of nutritional status in patients receiving home parenteral nutrition. Anthropometry detected changes in body weight secondary to changes in muscle and/or fat in 80% of patients. Pooling anthropometric data distors the relationship between variables owing to inter-individual variability when actual values are used. The method of successive differences is the preferred method of analysis for group anthropometric data.
Journal Article↗
Progesterone antagonists and progesterone receptor modulators.
Since the discovery of the antiprogestin RU 486 (mifepristone), other compounds have been synthesised that function as pure progesterone antagonists or progesterone receptor modulators. The latter are mixed agonists-antagonists. Mifepristone is usually used to terminate pregnancy but these compounds have numerous other applications in female healthcare. Mifepristone is an excellent agent for emergency contraception. Many progesterone antagonists and progesterone receptor modulators display antiproliferative effects on the endometrium and thus have application in the treatment of endometriosis and uterine myoma without being associated with hypoestrogenism and bone loss. They also have contraceptive potential by suppressing follicular development, blocking the luteinising hormone surge and retarding endometrial maturation. Finally, they have clinical application in GeneSwitch system, a plasmid-based method enabling controlled expression of specific genes (e.g., erythropoietin) using a progesterone antagonist as the inducer.
Animals↗
Qualitative and quantitative analyses of resin-bound organic compounds.
Methods for qualitative and quantitative analyses of resin-bound organic compounds are essential tools for chemistry development in solid-phase combinatorial and parallel syntheses. Here we discuss the use of gel-phase 19F NMR, the fluoride ion-selective electrode method, and spectrophotometry for monitoring solid-phase reactions. Our results indicate that the application of these diverse methods for analyzing the outcome of solid-phase combinatorial synthesis are sensitive and conclusive.
Aldehydes↗
Urinary total oestrogen values determined by an automated method in normal and abnormal pregnancies.
Urinary total oestrogen values in late pregnancy have been determined by an automated, fluorimetric method based on the Kober reaction and Ittrich extraction. The normal range was obtained from 360 samples from 56 patients. The mean value at 40 weeks gestation was 52.6 mg/24 h and the 95 per cent probability bounds were 29.1 and 95.3 mg/24 h, obtained after initial calculations on logarithm values. "Small for dates" foetuses in good condition at birth were associated with oestrogen values generally below the normal mean. They were usually well discriminated from foetuses that died in the uterus. These were always associated with oestrogen values below or approaching 10 mg/24 h before death except when growth had been normal and death was due to mechanical complications at delivery.
Autoanalysis↗
Poland and US collaborative study on cardiovascular epidemiology. II. Correlates of lipids and lipoproteins in men and women aged 35-64 years from selected Polish rural, Polish urban, and US samples.
Three diverse samples of men and women aged 35-64 years living in urban Poland, rural Poland, and the United States, are described and subsequently analyzed by multiple regression methods. Total cholesterol, low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol, and the natural logarithm (ln) of triglycerides are treated separately as dependent variables, with several demographic, behavioral, and biologic factors as independent variables. In the analyses of total cholesterol, systolic blood pressure was statistically significant in men and women in all three samples, while Quetelet index, cigarette smoking, age, ethanol consumption, and education were significant in at least one of the samples. In the LDL cholesterol analyses, Quetelet index and cigarette smoking were the predominant variables; in the HDL cholesterol analyses, Quetelet index, cigarette smoking, ethanol consumption, and age were key variables; and in the ln triglycerides analyses, Quetelet index, cigarette smoking, education, and systolic blood pressure were significant.
Adult↗
Endoscopic balloon dilatation of colonic anastomotic strictures.
Nine postoperative colonic and rectal strictures were treated using dilatation balloons passed over a guide-wire introduced endoscopically. Six strictures resolved after a single dilatation. The method is simple, safe, effective and avoids further surgery.
Adult↗
Perchlorate enhances transmission in skeletal muscle excitation-contraction coupling.
The effects of the anion perchlorate (present extracellularly at 8 mM) were studied on functional skeletal muscle fibers from Rana pipiens, voltage-clamped in a Vaseline gap chamber. Established methods were used to monitor intramembranous charge movement and flux of Ca release from the sarcoplasmic reticulum (SR) during pulse depolarization. Saponin permeabilization of the end portions of the fiber segment (Irving, M., J. Maylie, N. L. Sizto, and W. K. Chandler. 1987. Journal of General Physiology. 89:1-41) substantially reduced the amount of charge moving during conventional control pulses, thus minimizing a technical error that plagued our previous studies. Perchlorate prolonged the ON time course of charge movement, especially at low and intermediate voltages. The OFFs were also made slower, the time constant increasing twofold. The hump kinetic component was exaggerated by ClO4- or was made to appear in fibers that did not have it in reference conditions. ClO4- had essentially no kinetic ON effects at high voltages (> or = 10 mV). ClO4- changed the voltage distribution of mobile charge. In single Boltzmann fits, the midpoint potential V was shifted -20 mV and the steepness parameter K was reduced by 4.7 mV (or 1.78-fold), but the maximum charge was unchanged (n = 9). Total Ca content in the SR, estimated using the method of Schneider et al. (Schneider, M. F., B. J. Simon, and G. Szucs. 1987. Journal of Physiology. 392:167-192) for correcting for depletion, stayed constant over tens of minutes in reference conditions but decayed in ClO4- at an average rate of 0.3 mumol/liter myoplasmic water per s. ClO4- changed the kinetics of release flux, reducing the fractional inactivation of release after the peak. ClO4- shifted the voltage dependence of Ca release flux. In particular, the threshold voltage for Ca release was shifted by about -20 mV, and the activation of the steady component of release flux was shifted by > 20 mV in the negative direction. The shift of release activation was greater than that of mobile charge. Thus the threshold charge, defined as the minimum charge moved for eliciting a detectable Ca transient, was reduced from 6 nC/microF (0.55, n = 7) to 3.4 (0.53). The average of the paired differences was 2.8 (0.33, P < 0.01). The effects of ClO4- were then studied in fibers in modified functional situations. Depletion of Ca in the SR, achieved by high frequency pulsing in the presence of intracellular BAPTA and EGTA, simplified but did not eliminate the effects of ClO4-.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗
Intramuscular droperidol versus intramuscular dimenhydrinate for the treatment of acute peripheral vertigo in the emergency department: a randomized clinical trial.
OBJECTIVE: The emergency department (ED) treatment of acute peripheral vertigo (APV) has not been well studied. The purpose of this study was to determine the efficacy of intramuscular (IM) droperidol vs IM dimenhydrinate, in the treatment of ED patients with APV. METHODS: The study was a randomized, double-blinded clinical trial, performed at a suburban, teaching ED. A convenience sample of adult patients with symptoms and signs consistent with rigid diagnostic criteria for APV were randomized to one of two treatment groups. Patients more than 65 years of age were excluded to reduce the likelihood of diagnostic misclassification. Demographic and historical features were recorded on a standardized data form. Patients recorded their initial level (t0) of discomfort on a 10-centimeter (cm) visual analog scale (VAS). Treatment group 1 received 2.5 mg droperidol IM, while treatment group 2 received 50 mg dimenhydrinate IM. After 30 minutes (t30), patients again recorded the severity of their symptoms on the VAS. Chi-square, t-tests, and Mann-Whitney were used for statistical comparison as appropriate. All tests were two-tailed, with alpha set at 0.05. Primary outcome parameters were the mean change in VAS score from t0 to t30, and the percentage of patients in each treatment group who felt well enough to go home after t30 without further ED intervention. RESULTS: There were 20 patients in the droperidol group and 20 in the dimenhydrinate group. The two groups were similar with respect to mean age (40 +/- 13 years droperidol vs. 42 +/- 13 years dimenhydrinate; p = 0.6), female sex (60% vs. 50%; p = 0.7), and mean median duration of symptoms [3 (interquartile range 2-12) vs 9 (interquartile range 2-30) hours; p = 0.2]. Mean initial t0 VAS scores were 7.2 +/- 2.3 and 7.8 +/- 1.9 (p = 0.47). Both treatment groups had mean reductions in VAS scores at t30 of 3.3 [95% confidence interval (95% CI) = 2.3 to 4.3]. At t30, 42% of patients in the droperidol group and 45% of patients in the dimenhydrinate group felt well enough to go home without further ED intervention. CONCLUSIONS: The authors found no difference between the therapeutic efficacies of IM droperidol and dimenhydrinate for the treatment of acute peripheral vertigo.
Adult↗
Intrinsic optical and passive electrical properties of cut frog twitch fibers.
This article describes a new apparatus for making simultaneous optical measurements on single muscle fibers at three different wavelengths and two planes of linear polarization. There are two modes of operation: mode 1 measures the individual absorbances of light linearly polarized along and perpendicular to the fiber axis, and mode 2 measures retardation (or birefringence) and the average of the two absorbance components. Although some intact frog twitch fibers were studied, most experiments used cut fibers (Hille, B., and D. T. Campbell. 1976. Journal of General Physiology. 67:265-293) mounted in a double-Vaseline-gap chamber (Kovacs, L., E. Rios, and M. F. Schneider. 1983. Journal of Physiology. 343:161-196). The end-pool segments were usually exposed for 2 min to 0.01% saponin. This procedure, used in subsequent experiments to make the external membranes in the end pools permeable to Ca indicators (Maylie, J., M. Irving, N. L. Sizto, G. Boyarsky, and W. K. Chandler. 1987. Journal of General Physiology. 89:145-176; Maylie, J., M. Irving, N. L. Sizto, and W. K. Chandler. 1987. Journal of General Physiology. 89:41-143), was routinely employed so that all our cut fiber results would be comparable. A simple method, which does not require microelectrodes, allowed continual estimation of a fiber's membrane (rm) and internal longitudinal (ri) resistances as well as the external resistance (re) under the Vaseline seals. The values of rm and ri obtained from cut fibers with this method agree reasonably well with values obtained from intact fibers using microelectrode techniques. Optical measurements were made on resting and action potential-stimulated fibers. The intrinsic fiber absorbance, defined operationally as log10 of the ratio of incident light to transmitted light intensity, was similar in intact and cut preparations, as were the changes that accompanied stimulation. On the other hand, the resting birefringence and the peak of the active change in cut fibers were, respectively, only 0.8 and 0.7 times the corresponding values in intact fibers. Both the amplitude and the half-width of the active retardation signal increased considerably during the time course of cut fiber experiments; a twofold increase in 2 h was not unusual. Such changes are probably due to a progressive alteration in the internal state of the cut fibers.
Action Potentials↗
Transabdominal chorion villus biopsy: 100 consecutive cases.
A series of 100 transabdominal chorionic villus biopsies were carried out for maternal age (34 patients), fetal sexing (15), previous aneuploidy (21), biochemical analysis (5), gene-probe analysis (17), and oligohydramnios or fetal anomaly (6). 18 patients were over 14 weeks pregnant at the time of sampling. Tissue samples were obtained from 98 patients, including one set of twins. All 99 tissue samples proved adequate for laboratory diagnosis. Chromosome mosaicism was encountered in 4 cases (among direct preparation karyotypes in 1 case, between direct and cultured cells in 2 cases, and between chorion cells [both direct and cultured] and the fetus in 1 case). No patient miscarried but 1 had a stillbirth and 1, who had undergone transcervical biopsy before referral to our hospital, started to bleed before termination of pregnancy because of a diagnosis of cystic fibrosis. These data suggest that the transabdominal method of chorion biopsy will fulfil its theoretical and early promise.
Chorionic Villi↗
The enantioselective determination of chlorpheniramine and its major metabolites in human plasma using chiral chromatography on a beta-cyclodextrin chiral stationary phase and mass spectrometric detection.
A sensitive enantioselective high-performance liquid chromatographic (HPLC) method has been developed for the simultaneous determination of plasma concentrations of (-)(R)- and (+)(S)-chlorpheniramine (CP) and their metabolites, desmethyl-chlorpheniramine (DCP), didesmethyl-chorpheniramine (DDCP) and chlorpheniramine N-oxide (CPNO). Enantioselective separations were achieved on a beta-cyclodextrin chiral stationary phase (CYCLOBOND I 2000) with a mobile phase consisting of diethylamine acetate (0.25%, pH 4.4):methanol:acetonitrile [85:7.5:7.5, (v/v/v)]and a flow-rate of 0.5 ml/min. For CP, the enantioselectivity (alpha) of the separation was 1.12 with a resolution factor (R(s)) of 1.17. The method was validated for CP by using mass spectroscopy detection (MSD). Concentrations of each enantiomer could be measured down to 125 pg/ml from a 1-ml plasma sample. Extracted calibration curves were linear from 0.13 to 50.00 ng/ml for each enantiomer. The method was applied to samples from two clinical studies.
Adult↗
Computational analysis of evolution and conservation in a protein superfamily.
Many gene superfamilies have hundreds or thousands of members and hence pose a significant challenge when performing a large-scale phylogenetic analysis. Derivation of the most accurate alignment possible and inference of evolutionary relationships (with an appropriate measure of confidence) are significant "bottlenecks" in the process. A generally applicable strategy is outlined for identifying and aligning sequences, performing simple analysis of the resulting alignment, and inferring evolutionary relationships. Reference is made to the serpin superfamily. The 'partition cluster' method, a relatively rapid technique for extracting underlying associations from phylogenetic bootstrap trees, is also presented.
Computational Biology↗
Frequent detection of acute primary HIV infection in men in Malawi.
BACKGROUND: Acute (antibody-negative) HIV infection is associated with high transmission potential but is rarely recognized. DESIGN: Cross-sectional study. METHODS: We examined the prevalence and predictors of acute HIV infection among 1361 consecutive male outpatients attending sexually transmitted disease (STD; n = 929) and dermatology (n = 432) clinics in Lilongwe, Malawi. Serum specimens negative for HIV antibodies were screened by HIV RNA PCR using a highly specific pooling/resolution testing algorithm. RESULTS: Five-hundred and fifty-three men (40.6%) were HIV antibody positive and 24 (1.8%) had acute HIV infection; 23 of 24 acutely infected men were from the STD clinic, where they represented 4.5% of all HIV antibody-negative men and 5.0% of all HIV infections. HIV RNA levels for acutely infected men were significantly higher [median (interquartile range), 6.10 (5.19-6.54) log10 HIV RNA copies/ml] than for 58 HIV antibody-positive men [4.42 (3.91-4.95) log10 copies/ml; P < 0.0001]. The factor most strongly associated with acute HIV infection was STD clinic attendance: (odds ratio, 15.2; 95% confidence interval, 2.04-113.0). In multivariate analysis considering only STD patients, factors associated with acute HIV infection included inguinal adenopathy, genital ulceration and age 24-26 years, the age stratum associated with peak incidence of HIV infection among Malawian men. CONCLUSIONS: Traditional HIV antibody tests alone are not sufficient to exclude HIV infection among men with acute STD in Malawi due to a surprising proportion of acute HIV infections in this population. Alternative screening methods are required for diagnosis of acute HIV infection; such screening could be important for research and for prevention of the sexual transmission of HIV in select populations.
Acute Disease↗