Search PubMed⌕ Search

Biomedical subjects

J W Allen

Publications and source records attributed to J W Allen.

At least 163 records · Page 9Linked to original sources
PubMed1983

Clinical data versus noninvasive testing as an estimate of coronary status.

The step from coronary angiography to surgery is taken primarily on the basis of the ejection fraction (EF) and number of diseased vessels (NV), taken jointly as coronary status (CS). This study reviewed (1) how well EF, NV and CS are estimated from clinical data, (2) how much improvement is gained by adding noninvasive data, (3) how good this model is when applied to a larger cohort and (4) whether the decision to angiography can be made on the basis of CS estimated from clinical data alone. A quantitative definition of CS was established as a principal component of EF and NV. Estimates of EF, NV and CS were made from clinical data of 60 patients. Correlations with the actual values were EF 87%, NV 93% and CS 93%. When noninvasive data were added to this model, the correlations increased to EF 95%, NV 99% and CS 98%. When the clinical data model was applied to 169 patients, the correlations decreased to EF 77%, NV 71% and CS 74%. CS estimated from clinical data alone was set up as a test for angiography for 169 patients. This test had a sensitivity of 98% and a specificity of 63%, demonstrating the feasibility of using clinical data alone in deciding angiography.

Angiography↗
PubMed1983

Mitral E point septal separation: a reliable index of left ventricular performance in coronary artery disease.

The diagnostic value of E point septal separation (EPSS) was assessed in 108 patients with coronary artery disease who underwent coronary angiography and M-mode echocardiography within a 2-year period at LAC/USC Medical Center. In patients with anterior myocardial infarction, EPSS correlated well with angiographic ejection fraction, with a specificity of 85% and sensitivity of 82%. In inferior myocardial infarction, a 21% frequency of falsely elevated EPSS values was encountered; the sensitivity for detecting reduced ejection fraction was 100% and the specificity was 67%. In combined anterior and inferior myocardial infarction, EPSS accurately estimated abnormal ejection fractions with a sensitivity and specificity of 100%. An abnormal EPSS (more than 7 mm) was found to be more sensitive (87%) and specific (75%) in detecting individuals with angiographically reduced ejection fraction (less than 50%) compared to other echocardiographic indices of pump function. Importantly, EPSS was effective in estimating left ventricular function in the presence of left bundle branch block, paradoxical septal motion, and angiographic septal, posterior, and anterior wall motion abnormalities.

Adult↗
PubMed1983

A controlled trial of cinromide.

A double-blind controlled trial of cinromide in 25 adult subjects with refractory epilepsy using the maximum tolerated dose showed that it possessed no significant antiepileptic properties.

Adolescent↗
PubMed1982

The role of face flies in an episode of infectious bovine keratoconjunctivitis.

Cattle partially protected from face flies (Musca autumnalis) had much less infectious bovine keratoconjunctivitis and yielded fewer isolated of hemolytic Moraxella bovis than did similar cattle that received no face fly protection. The number of new isolated of M bovis from the unprotected cattle was highly correlated with the number of face files observed on the cattle. Close physical proximity to cattle infected with M bovis was important in the spread of the bacteria to previously uninfected cattle; however, it did not require physical contact among the cattle to spread from herd to herd. Moraxella bovis first began to spread from herd to herd after face fly populations exceeded 10/animal for 1 month. Keratoconjunctivitis was not observed in 53% of the cattle from which M bovis was isolated. Moraxella bovis was isolated from 4 of 45 pools of face files collected from animals in the untreated herds.

Animals↗
PubMed1982

Comparative genotoxicity studies of ethyl carbamate and related chemicals: further support for vinyl carbamate as a proximate carcinogenic metabolite.

In vivo and/or in vitro mammalian cell systems were used to evaluate sister chromatid exchange (SCE) induction and gene mutagenesis effects following exposure to ethyl carbamate (urethane), vinyl carbamate, ethyl N-hydroxycarbamate, and 2-hydroxyethyl carbamate. Although ethyl carbamate caused dose-dependent increases in SCE when injected into mice, it was ineffective for inducing SCE and gene mutation (6-thio-guanine resistance) in Chinese hamster V-79 cells cultured with or without the addition of S9 enzyme mix during treatment. Chemical-specific patterns of genotoxicity were evident for the known or suspect metabolites under test: only vinyl carbamate consistently (in vivo and in vitro) revealed strong activity for the genetic endpoints. SCE induction levels of 5-8 times baseline were observed after animal or cell culture exposures to vinyl carbamate. Doses required to produce this effect in V-79 cells in the presence of S9 mix were approximately 100 times lower than those needed when S9 was absent. The extensive gene mutagenesis (approaching 600 mutants/10(6) survivors) noted was completely dependent upon the presence of S9 mix. These observations are consistent with current theory holding that vinyl carbamate is a metabolic intermediate of ethyl carbamate, and is converted to the ultimately reactive species (presumably, vinyl carbamate epoxide) which is responsible for ethyl carbamate carcinogenesis.

Animals↗
PubMed1982

Acute cervical cord injuries in patients with epilepsy.

Seven cases with acute cervical cord lesions associated with a fit and fall, were found in approximately 500 patients with epilepsy over a period of 7 years. In all patients the epilepsy was refractory to drug therapy and six suffered tonic fits which resulted in falls and frequent head injuries. Notable radiological changes were found in the cervical spine; there was ankylosis in five, hyperostosis in four and the minimum sagittal diameter of the bony canal was less than 11mm in three cases. The findings indicate that repetitive trauma may be a factor in producing bony changes in the cervical spine which put the patient at risk of cervical cord injury, especially when the spinal canal is developmentally narrow.

Adult↗
PubMed1981

Sister-chromatid exchange analyses in rodent maternal, embryonic and extra-embryonic tissues: transplacental and direct mutagen exposures.

Sister-chromatid exchange (SCE) analyses were conducted in maternal, embryonic and extraembryonic tissues of pregnant rats and mice. The various tissues were substituted in vivo with 5-bromodeoxyuridine (BrdU) by implantation of a BrdU tablet in pregnant animals at mid-gestation. Following maternal exposure to 5-20 mg/kg cyclophosphamide, embryonic liver cells demonstrated dose-dependent SCE increases up to 10-fold that of control. Rat embryos revealed little intralitter variability for this transplacental effect. Maternal marrow and yolk sac cells examined in the rat also underwent significant increases in SCE, although to different extents. While marrow SCE frequencies were similar to those of embryo liver, yolk sac SCE frequencies were generally much lower. SCE analyses were also conducted in rat yolk sac cells substituted in vivo with BrdU and subsequently explanted to whole-embryo culture. In vitro exposure to cyclophosphamide at concentrations up to 100 microgram/ml had no SCE-inducing effect. However, similar exposures to phosphoramide mustard, a presumed metabolite of cyclophosphamide, caused dose-dependent increases in SCE up to 8-fold higher than control at 2 microgram/ml. Thus, cyclophosphamide appears to require maternal metabolic activation in order to cause an increased SCE frequency in yolk sac cells. The system described permits versatile SCE analyses which can help to define relative maternal and embryo tissue-specific sensitivities to chemical-induced genetic damage.

Animals↗
PubMed1980

Tissue-specific induction of sister chromatid exchanges by ehtyl carbamate in mice.

Sister chromatid exchange (SCE) techniques were used to analyze the genetic effects of ethyl carbamate (urethane) in cultured mouse-bone marrow cells, and in several different mouse tissues in vivo. Ethyl carbamate concentrations up to 5.0 mg/ml were ineffective in causing a significant elevation of SCE in vitro. After in vivo drug administration, bone marrow, liver and spermatogonial cells all revealed significant dose-related increases in SCE. Baseline and relative incremental levels of SCE were somatic vs germ tissue-specific. Regenerating liver cells exhibited significantly greater absolute SCE values than all other tissues examined. Marrow cells revealed intermediate values, while germ cells were the least sensitive in SCE responsiveness. Spermatogonia required a fourfold higher dose, over that effective in somatic tissues, to promote an approximate doubling of the baseline SCE level. In vivo SCE analysis affords sensitive risk assessments for different tissues. Thus, this approach; should be generally useful for studying compounds with questionable mutagenic potential, and/or those exerting target organ specificities of related biological activity (eg, toxicity, carcinogenesis).

Animals↗
PubMed1980

Managing the evolution of a laboratory computer system.

The Laboratory Information System (LABIS) of the National Naval Medical Center, Bethesda, Md., was installed in 1974. Since that time, the system has undergone transitions which suggest that its evolution proceeded in three distinct stages. The author details the different management techniques and supervisory qualifications that each stage of growth requires, and he explains how an understanding of these requirements will enable the pathologist to adjust better to the evolution of the system.

Communication↗
PubMed1979

R--pulse wave timing: a technique for continuous cardiovascular monitoring in obstetrics--preliminary report.

A simple, noninvasive technique for continuous cardiovascular monitoring in obstetrics using R--pulse wave timing is described. This preliminary study suggests that different maternal heart rate/R pulse patterns are found in different clinical circumstances. A significant decrease in the R pulse interval occurred in the third trimester in both normal and diabetic women in the left lateral position when compared to the supine position. The R pulse intervals were all prolonged in the standing position in both gravid and nongravid women. During labor R pulse interval usually shortened during uterine contraction. Prolongation of R pulse interval was observed during thiopental injection, hypotension, and excessive bleeding at cesarean section. Exercise testing in healthy male subjects suggested that the change in R pulse interval becomes constant when the oxygen consumption rate reaches a plateau at 100% maximal work load. Further extensive clinical study appears worthwhile since it may add another dimension to cardiovascular monitoring and give an early indication of cardiovascular reserve.

Anesthesia, Obstetrical↗
PubMed1979

BrdU-dye characterization of late replication and meiotic recombination in Armenian hamster germ cells.

In vivo BrdU-dye methodology is used to reveal patterns of replication kinetics and meiotic recombination in male germ cells of the Armenian hamster. Analogue substitution over a fraction of the DNA synthesis period results in distinctive 33258 Hoechst fluorescence staining of late replicating chromatin, detectable at spermatogonial or spermatocyte I and II stages. Spermatogonial cells which are extensively substituted with BrdU over the penultimate synthesis period reveal sister chromatid differentiation in all chromosomes of primary or secondary spermatocytes. In chiasmatic regions, exchanges between unlike-stained non-sister chromatids are indicated by isolatelled segments, while those occurring between like-stained non-sister chromatids are not directly detected. In sex chromosomes from young animals, these alternative images occur in a ratio of 1:1, which supports the concept that homologue non-sister chromatid regions are randomly broken and re-united in the process of chiasma formation. Deviations from randomness appeared to occur in older animals. Sex bivalent chiasmata are either coincident with points of visible exchange, or they appear to have variable degrees of terminalization. Secondary spermatocytes display sharp chromatid contrast, and aid in mapping the positions and frequencies of homologue exchanges.

Animals↗
PubMed1979

The incidence of different types of fetal movements during pregnancy.

In high risk pregnancies with severe fetal distress, a reduction of fetal movements may take place before fetal death occurs. This decrease is accompanied by a weakening of the fetal movements. One hundred and twenty pregnant women (310 recordings) between 20 and 41 weeks gestation recorded fetal movements and classified them into weak, strong, and rolling. The movements noted by the woman were correlated to those recorded by a fetal movements recorder. The rate of weak movements gradually decreased until the 36 to 37th week, while the strong and rolling movements increased. From the 36 to 37th week till term weak movements increased again with a decline in strong and rolling movements. Before fetal death, or in severe fetal distress with decreased total movements, the relative rate of weak movements increased. Reduction in daily total movements without a change in the distribution of the type of movement may not indicate fetal distress.

Adult↗
PubMed1979

Diastolic flutter of aortic valves in aortic regurgitation: a report of seven cases.

Seven patients with aortic regurgitation, manifesting diastolic flutter of the aortic valve cusps (DFAVC) in the echograms, are described. Five patients with infective endocarditis revealed coarse or fine, irregular DFAVC. Two patients with severe aortic regurgitation and a musical murmur manifested regular DFAVC with a frequency identical to that of a simultaneously recorded diastolic murmur. Of the 5 patients with infective endocarditis, 4 required urgent aortic valve replacement and 1 died. The 2 patients with musical murmurs are clinically stable without surgery. This report extends the clinical spectrum of patients with DFAVC and describes the character of the flutter in patients with muscial murmurs. Furthermore, it suggests that DFAVC is a sign of severe aortic regurgitation.

Adult↗