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Biomedical subjects

C Brown

Publications and source records attributed to C Brown.

At least 415 records · Page 23Linked to original sources
PubMed1987

Comparison of cineradiographic and photodetection techniques for assessing velopharyngeal function during speech.

This study investigated the extent to which high-speed lateral-view cineradiography and a photodetector system described by Dalston (1982) provided comparable information concerning velopharyngeal activity. We observed the production of isolated utterances and running speech for 2 subjects in three contexts. A comparison was made between the times at which the velopharyngeal port was observed by each method to begin opening, reach maximal opening, begin closing, and initially attain closure. The photodetector system was found to be sensitive to changes in velar position observed by cineradiography. The correlation between the magnitude of photodetector output and the magnitude of velar displacement from the posterior pharyngeal wall was .89 for Subject 1 and .78 for Subject 2. The lack of a perfect relation between the output of the photodetector device and movements of the velum observed by cineradiography was not unexpected given the two-dimensional limitation of lateral cineradiography and the complexity of events associated with changing port size. The significance of these findings is discussed with respect to the potential research and clinical uses of this photodetector system.

Cineradiography↗
PubMed1987

Effect of cisapride on the gastrointestinal transit of a solid meal in normal human subjects.

The effect of cisapride, a new gastrointestinal prokinetic agent, on the transit of a standard meal through the stomach, small intestine and colon was studied in 10 normal subjects. Cisapride had no significant effect on gastric emptying but decreased mouth to caecum transit time (p less than 0.01). Stool weight and frequency were not significantly increased but the time for the first appearance of stool markers and the arrival of 20% and 50% of stool markers was decreased after cisapride (p less than 0.05).

Adult↗
PubMed1987

Autoantibody to aldolase in acute and chronic hepatitis.

Sera from 82 patients with acute or chronic hepatitis and 40 chronic carriers of hepatitis B were examined by ELISA and immunoblotting for reactivity with the glycolytic enzyme aldolase. The results of the ELISA tests, expressed as a percentage of a positive control, were compared to those obtained with sera from 39 patients with rubella, 11 with cytomegalovirus infection and 74 healthy subjects. The ELISA reaction with sera, expressed as mean +/- standard deviation was, for 15 patients with hepatitis A, 58.3 +/- 20.5%; 15 with hepatitis B, 59.5 +/- 42.18; 23 with hepatitis non-A, non-B 51.1 +/- 34.4%; 11 with HBsAg positive chronic active hepatitis, 70.1 +/- 31.5%; and 17 with autoimmune chronic active hepatitis, 66.8 +/- 21.4%. All values were significantly (p less than 0.05-p - less than 0.001) higher than those obtained with sera from carriers of hepatitis B surface antigen, 25.6 +/- 27.2%; rubella, 21.1 +/- 20.0%; cytomegalovirus infection, 19.2 +/- 27.8%; or healthy subjects, 20.9 +/- 16.2%. In two randomly selected sera, reactivity with aldolase by ELISA was neutralized by absorption with the enzyme. Selected sera showing reactivity by ELISA reacted by immunoblotting with aldolase. The findings suggest that acute or chronic liver damage may provoke the production of autoantibodies to aldolase.

Acute Disease↗
PubMed1987

Cancer risk-assessment models: anticipated contributions from biochemical epidemiology.

Uncertainties in quantitative assessment of cancer risk limit the scientific role of this activity in the policy and regulatory debate on cancer control. Risk-assessment strategies and models are highly dependent on the nature and quality of the data available. However, accumulating laboratory and epidemiologic studies that are shedding new light on mechanisms of carcinogenesis have not yet been integrated into current risk-assessment models. Future developments in risk assessment may, therefore, be anticipated by considering the type of epidemiologic data that may soon be generated. Three important areas of epidemiologic and biochemical research should reduce some of the uncertainty in quantitative risk assessment by making it possible to: identify stages of the disease process through precursor lesions, biochemical markers, and to determine at which stage the carcinogen acts; identify subpopulations that are at enhanced or reduced susceptibility to carcinogenic influences; and obtain additional and refined indices of dose. Much of this research is being called "biochemical epidemiology." Strategies for incorporating these newly generated data into regulatory decisions vary from developing new mechanistically based mathematical models to applying existing models to biologically distinct subpopulations.

Carcinogens↗
PubMed1986

The use of flanking markers in prediction for Duchenne muscular dystrophy.

Seventy three sisters of boys with Duchenne muscular dystrophy and their families were studied using up to seven deoxyribonucleic acid (DNA) probes linked to the gene on the short arm of the X chromosome. Fifty three (73%) were informative for flanking markers, a further 18 (24%) being informative for a single marker only. Predictions based on pedigree structure and creatine kinase information from the individuals and their female relatives gave more than half (55%) of the sisters a risk for being a carrier of below 10% or above 90%. The addition of information derived from the inheritance of flanking DNA markers, where they exist, improves the situation so that many more sisters (77%) can be allocated into either high or low risk categories.

Adolescent↗
PubMed1986

Doubly labeled water method: in vivo oxygen and hydrogen isotope fractionation.

The accuracy and precision of the doubly labeled water method for measuring energy expenditure are influenced by isotope fractionation during evaporative water loss and CO2 excretion. To characterize in vivo isotope fractionation, we collected and isotopically analyzed physiological fluids and gases. Breath and transcutaneous water vapor were isotopically fractionated. The degree of fractionation indicated that the former was fractionated under equilibrium control at 37 degrees C, and the latter was kinetically fractionated. Sweat and urine were unfractionated. By use of isotopic balance models, the fraction of water lost via fractionating routes was estimated from the isotopic abundances of body water, local drinking water, and dietary solids. Fractionated water loss averaged 23% (SD = 10%) of water turnover, which agreed with our previous estimates based on metabolic rate, but there was a systematic difference between the results based on O2 and hydrogen. Corrections for isotopic fractionation of water lost in breath and (nonsweat) transcutaneous loss should be made when using labeled water to measure water turnover or CO2 production.

Body Water↗
PubMed1986

Effect of coronary stenotic lesions on regional myocardial blood flow at rest.

To determine the effect of atherosclerotic coronary lesions on myocardial blood flow in patients at rest, regional myocardial blood flow was measured distal to stenotic lesions in 29 patients with isolated proximal lesions of the left anterior descending artery. Severity of coronary stenosis was measured by computer-assisted cinevideodensitometric analysis of digitized coronary arteriograms. Regional myocardial blood flow was measured from the clearance rate of intracoronary 133Xe injected into the left main coronary artery and recorded with a multicrystal scintillation camera. In 21 patients with stenotic lesions ranging from 19% to 84% area reduction, distal regional myocardial blood flow was normal. In all eight patients with reduced regional myocardial blood flow distal to left anterior descending lesions, the minimum area of each stenotic lesion was less 0.80 mm2 (mean 0.34 +/- 0.2 mm2), minimum calculated diameter was less than 1 mm (mean 0.59 +/- 0.3 mm), and percent stenosis, based on the reduction in cross-sectional area, was greater than 85% (mean 94 +/- 4%). For all patients, distal flow, expressed as a fraction of normal flow, correlated with the lesion cross-sectional area (r = .84), minimum luminal diameter (r = .84), and percent area stenosis (r = -.70). Thus, resting myocardial blood flow distal to stenotic lesions of the proximal coronary arteries remains normal until the degree of narrowing is severe. The dimensions observed for critical coronary stenotic lesions correlate well with theoretical predictions based on fluid mechanics and with experimental preparations in laboratory animals.

Cineangiography↗
PubMed1986

Corticotrophin-releasing factor in extra-hypothalamic brain of the mouse: demonstration by immunoassay and immunoneutralization of bioassayable activity.

Corticotrophin-releasing factor (CRF) bioactivity has been described in the extra-hypothalamic brain, but its relationship to hypothalamic CRF has remained questionable. Of the seven regions of the mouse brain examined, highest concentrations of CRF-like immunoreactivity (CRF-LI) and bioassayable CRF activity were present in the median eminence and hypothalamus. However, substantial CRF-LI and bioassayable CRF activity were also seen in brain extracts from the amygdala, thalamus, frontal cortex, pons medulla and cerebellum. Bioactivity was largely neutralized by prior incubation with heat-inactivated antiserum to ovine CRF. These findings, in conjunction with previous immunocytochemical evidence, strongly suggest that a substance closely resembling hypothalamic CRF is present in the extrahypothalamic brain of the mouse.

Amygdala↗
PubMed1986

Free radicals in skin exposed to dithranol and its derivatives.

The generation of persistent free radical species derived from antipsoriatic drugs in their target tissue under use conditions is reported. Dithranol (anthralin, 1,8-dihydroxy-9-anthrone) and chemical analogues were applied topically to the ear of the pig and the time course of the production of the resulting free radicals was followed by electron spin resonance spectroscopy in biopsy samples. The spectral characteristics observed correspond to data previously reported in vitro for the anthralin-10-yl radical. The role of these radical species in the mode of action of the drug is discussed.

Animals↗
PubMed1986

Autoantibodies to intermediate filaments in acute viral hepatitis A, B and non-A, non-B are directed against vimentin.

Using ELISA and immunoblotting, autoantibodies to vimentin were sought in sera from 10 patients with acute hepatitis A, 10 with acute hepatitis B, 13 with acute non-A, non-B hepatitis, 16 with autoimmune chronic active hepatitis, 17 with cytomegalovirus infection and 40 from healthy persons. The ELISA results were expressed as a percentage of the value obtained with a monoclonal antibody to vimentin. The results (mean and SD) for acute hepatitis A (51.2 +/- 21.7%), acute hepatitis B (44.5 +/- 28.2%) and acute hepatitis non-A, non-B (43.0 +/- 16.4%) were significantly (p less than 0.01) higher than those for autoimmune chronic active hepatitis (20.5 +/- 7.7%), cytomegalovirus infection (25.9 +/- 12.2%) and healthy controls (16.8 +/- 9.3%). Immunoblotting showed that sera from patients with acute viral hepatitis reacted with 57 kd vimentin in triton-cytoskeletal extracts of fibroblasts. These results show that autoantibodies to vimentin are present in sera from patients with acute hepatitis A, B and non-A, non-B. Antivimentin autoantibodies may be useful in the diagnosis of acute non-A, non-B hepatitis.

Autoantibodies↗
PubMed1986

Cumulative incidence rates for Hodgkin's disease and other hematologic malignancies, with special reference to age-related carcinogenesis.

The cumulative incidence rate throughout the life span was analyzed for 4,865 Hodgkin's disease cases, in comparison with 16,015 malignant lymphomas (ML), 1,694 acute lymphocytic leukemias (ALL), 3,967 acute myeloid leukemias (AML), 2,109 chronic myeloid leukemias (CML), and 4,752 chronic lymphoid leukemias (CLL) in US white reported in the SEER program during 1973-1981. A log-linear increase was observed in ML, AML, CML, and CLL throughout the life-span, but only in childhood in ALL. Hodgkin's disease showed a steep increase until age 20-24, and then the increase became much more gradual. The cumulative incidence rates for males and females were parallel for ML and leukemias, but diverged for Hodgkin's disease (the rate for females had a lower slope than that for males after age 20-24). This difference was mainly caused by a lower frequency in females of mixed cellularity and lymphocyte predominance subtypes. The incidence curve of Hodgkin's disease was consistent with the two-stage model of carcinogenesis; it is likely that the proliferation of progenitor cells peaks at a young age and that the death rate of so-called intermediate cells is a primary influence during the subclinical stage. The cytogenesis of Hodgkin's disease and the histologic variation with special reference to the T-zone histiocytes suggest that a strong host defense mechanism against neoplastic change is involved, rather than different etiologic influences.

Adolescent↗
PubMed1986

Deaths following ingestion of a cardiotoxic plant in Kampuchean children in Thailand.

Twenty-seven Khmer children at a refugee camp in Thailand developed vomiting and diarrhea after ingestion of the seeds of the plant Erythrophleum succirubrum Gagnep. Two children died of cardiac arrest. Ingestion of seed of Erythrophleum species that contain digitalis-like alkaloids causes fatal epidemics of poisoning in children as well as livestock.

Arrhythmias, Cardiac↗