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Biomedical subjects

M H Smith

Publications and source records attributed to M H Smith.

At least 91 records · Page 5Linked to original sources
PubMed1985

Distribution of gamma exposure rates in a reactor effluent stream flood plain system.

Ground-level gamma dosimetry surveys were conducted along the length of a radiocesium-contaminated reactor effluent stream flood plain system to determine the extent and patterns of isotope distribution over a decade after reactor releases were stopped. The maximum mean exposure rates were found at upstream locations near the source of the contamination and in a downstream sedimentary delta. Gamma exposure rates were not uniformly distributed and high exposure rates were generally restricted to small areas of the flood plain. There was little similarity in either the spatial distribution or magnitudes of maximum gamma exposure rates across flood plains along the stream. Frequency the measured exposure rates tended to be highly skewed and most closely approximated the log-normal distribution in most areas along the stream. However, the complex and changing patterns of dose distributions strongly affected the ability to predict the probability of encountering unusually high exposure rates. Complex statistical and distributional models are required to provide precise descriptions of the dosimetry environment in such complex ecosystems and different models could be required on a site-by-site basis.

Cesium Radioisotopes↗
PubMed1985

Estimation of the response-error relationship in immunoassay.

Estimation of the response-error relationship in immunoassay provides a weighting function for the main analysis, and may in general be essential to ensure statistically valid data reduction. In this study we generated 50,000 sets of simulated radioimmunoassay response data with a computer, using five response-error functional forms that are commonly assumed. Parameters were estimated by three least-squares regression methods and three that are modifications of a maximum-likelihood method. Two likelihood estimators that require significantly different computing times were shown to be virtually indistinguishable, statistically more efficient than least-squares estimators, and-in contrast to least-squares estimators-to guarantee positive predicted variances in the range of the data.

Computers↗
PubMed1984

Cell-mediated immune response in cattle to bovine respiratory syncytial virus.

Cattle inoculated with bovine respiratory syncytial virus (BRSV) were evaluated for the development of a cell-mediated immune response. Results of the leukocyte migration-inhibition test under agarose and the delayed hypersensitivity test indicated that a cell-mediated immune response was elicited after intranasal inoculation of calves with BRSV. Migration inhibition in the leukocyte migration-inhibition test was detected by postinoculation day (PID) 5 and reached maximum inhibition on PID 21. Inhibition of leukocyte migration was still evident by PID 42 when values were still appreciably greater than preinoculation values. All of the calves inoculated with BRSV developed a delayed hypersensitivity skin response when challenge exposed intradermally with BRSV antigen.

Animals↗
PubMed1984

Do patients with thromboembolic disease have circulating platelet aggregates?

Reports of circulating platelet aggregates (ie, microemboli) in thromboembolism and other vascular disorders are based on a method (Wu and Hoak , 1974) in which venous blood is collected via scalp vein needle and tubing into either formaldehyde, which fixes aggregates, or EDTA, which disperses them. The ratio of platelet counts in platelet-rich plasma (PRP) from the two blood samples after centrifugation is interpreted as a measure of platelet aggregates in the circulation in vivo. We compared this standard Wu and Hoak technique with a modified one, in which blood was drawn directly into a syringe, and with a third method that avoided centrifugation by counting single platelets in whole blood. Both modified techniques could detect aggregates generated in vitro with adenosine diphosphate (ADP). In 12 normal subjects, the three methods were equivalent, but in 37 patients with thromboembolic disorders, the standard Wu and Hoak method gave a lower ratio than the other methods. Similar results were found in a subset of eight patients with myocardial infarction. Heparin treatment of patients did not influence the results. The data suggest that formation of platelet aggregates occurred during venipuncture. Platelets may be hyperactive in patients with thromboembolic disease and may form aggregates in vitro during collection, but the concept of chronic microembolism in such patients should be reassessed.

Blood Platelets↗
PubMed1983

Relative intestine length and feeding ecology of freshwater fishes.

There is a significant relationship between the intestine length (Y) and total body length (X) for 11 species of freshwater fish (Y = 0.08X1.42). Sufficient variation exists about this relationship to indicate important differences among the species' diets. The diets for each species, ranked on a Trophic Index scale determined from literature data, are negatively rank order correlated with the mean relative intestine lengths (rs = -0.67). There is no significant rank order correlation between the Trophic Indices determined from data on stomach contents and the mean relative intestine lengths for fish from a single creek.

Animal Nutritional Physiological Phenomena↗
PubMed1982

Osmoregulatory thirst in sheep is disrupted by ablation of the anterior wall of the optic recess.

Ablation of the organum vasculosum of the lamina terminalis (OVLT) and adjacent midline tissue in the anterior wall of the optic recess of the third ventricle resulted in greatly reduced water drinking to intracarotid infusion of hypertonic NaCl in sheep. Daily food and water intake and angiotensin II drinking were not consistently reduced by these lesions. Tissue in or close to the OVLT is probably involved in osmotically induced water-drinking.

Angiotensin II↗
PubMed1981

Epizootic hemorrhagic disease virus in Montana: isolation and serologic survey.

Epizootic hemorrhagic disease virus (EHDV) was isolated in Vero cell culture from the spleen and whole blood of a white-tailed deer (Odocoileus virginianus). A 10% spleen suspension caused acute hemorrhagic disease (HD) when inoculated into an experimental white-tailed deer and resulted in the recovery of EHDV from the blood of the experimental animal at 5 days after inoculation. The virus was identified as EHDV serotype 2 through indirect fluorescent antibody tests, electron microscopy, and reciprocal cross-neutralization tests. Approximately 73% (36/49) of the mule deer, 5% (2/42) of the white-tailed deer, and 79% (249/314) of the cattle samples tested from areas where HD had been reported were EHDV seropositive. Although none of the white-tailed deer was bluetongue virus seropositive, 29% of the mule deer and 3% of the cattle tested from "active" HD areas possessed bluetongue virus precipitating antibody.

Animals↗
PubMed1980

Morphogenesis and structure of caprine respiratory syncytial virus.

Cell cultures inoculated with caprine respiratory syncytial virus (RSV) were studied with light, fluorescent, and electron microscopy to determine the morphogenesis and structure of the virus. Small syncytia were seen after 36 hours in culture. After 48 hours in culture, syncytia were large and numerous and pleomorphic cytoplasmic inclusions were seen. These inclusions were more pronounced and numerous later in the infection cycle. Indirect immunofluorescence revealed a diffuse to granular cytoplasmic fluorescence with fluorescing fibrils on the cell surface. With the electron microscope, filamentous (100-160 nm) and spherical (90-160 nm) particles were seen budding off the cell membrane. The number of virus buds diminished with increased size of syncytia. Granular pleomorphic cytoplasmic inclusions were seen near the nucleus, and electron dense masses were seen just beneath the cytoplasmic membrane where large quantities of virus were budding from the cell surface. The first type of inclusion had distinct borders; the second diffuse borders and appeared to contain viral nucleoprotein. Negative staining revealed spherical, pleomorphic, and filamentous forms of the virus; the last form predominated. The virions were covered with club-shaped projections, and the nucleocapsids were seen as fragile strands frequently broken into fragments or as isolated rings. Morphogenesis and structure of the caprine RSV places this virus with the Pneumovirus genus of the Paramyxoviridae family.

Animals↗
PubMed1980

Effect of heparin and heparin fractions on platelet aggregation.

Porcine intestinal mucosal heparin induced aggregation of platelets in citrated platelet-rich plasma and enhanced platelet aggregation and serotonin secretion induced by other agents. This action of heparin was blocked by substances that elevate platelet cyclic AMP and by EDTA but not by inhibitors of platelet cyclooxygenase. The effect was not inhibited by apyrase or by N-amylthio-5'-AMP and therefore did not require the action of ADP, nor was there activation of platelet phospholipase. Platelet aggregation by heparin required a plasma cofactor different from the cofactor required for ristocetin. Fractionation of heparin yielded preparations that varied in molecular weight and, within a given molecular weight fraction, in affinity for antithrombin III. Fractions of high molecular weight (average 20,000) were more reactive with platelets than were fractions of low molecular weight (7,000). Anticoagulant activity did not parallel the platelet reactivity of heparin fractions. Among high molecular weight fractions, preparations of high or low antithrombin affinity were equally active in induction of platelet aggregation. In low molecular weight fractions, there was an inverse relationship between platelet reactivity and anticoagulant activity in normal platelet-rich plasma, but, in platelet-rich plasma depleted of antithrombin, low molecular weight fractions of high and low antithrombin affinity reacted equally with platelets. These results suggest that formation of an antithrombin-heparin complex protected platelets from aggregation by heparin. Selection of heparin fractions of low molecular weight and high antithrombin affinity may improve anticoagulant therapy and development of thromboresistant heparin-coated artificial materials.

Adenosine Diphosphate↗
PubMed1980

Identification and characterization of a bovine rhinovirus isolated from Iowa cattle with acute respiratory tract disease.

Viral isolate FS1-43 isolated from a calf with acute respiratory tract disease was characterized as a bovine rhinovirus. This virus was antigenically indistinguishable from rhinovirus strains C-07 and VC-96. The virus replicated in low passage Madin-Darby and Georgia bovine kidney cells. A relative noncytopathogenic replication occurred in epithelial bovine turbinate, bovine fibroblastic turbinate, and bovine lung cells. Ciliary activity of tracheal explants was unaffected during eight serial passages. Viral replication was detected earlier and viral titers were higher at 33 C than at 37 C. Rotation of cultures did not affect viral titers but was necessary to produce a cytopathic effect in Madin-Darby bovine kidney cells.

Animals↗
PubMed1980

Effects of sex, age, habitat and body weight on kidney weight in white-tailed deer.

Kidney (Y) and body (X) weights in kilograms are highly correlated (r = 0.88) in white-tailed deer. As in other mammals, the relationship between the two variables is curvilinear with Y = -2.493 X0.746. Habitat did not affect the parameters of the realationship although certain sex-age and sex month categories did. However, use of kidney weight in standardizing body condition indices in deer of different sizes still seems warranted for white-tailed deer in the southeastern United States during the hunting season because of the relatively high predictability of the overall kidney-body weight relationship.

Age Factors↗
PubMed1979

Phanerochaete chrysosporium beta-Glucosidases: Induction, Cellular Localization, and Physical Characterization.

Phanerochaete chrysosporium produces intracellular soluble and particulate beta-glucosidases and an extracellular beta-glucosidase. The extracellular enzyme is induced by cellulose but repressed in the presence of glucose. The molecular weight of this enzyme is 90,000. The K(m) for p-nitrophenyl-beta-glucoside is 1.6 x 10 M; the K(i) for glucose, a competitive inhibitor, is 5.0 x 10 M. The K(m) for cellobiose is 5.3 x 10 M. The intracellular soluble enzyme is induced by cellobiose; this induction is prevented by cycloheximide. The presence of 300 mM glucose in the medium, however, had no effect on induction. The K(m) for p-nitrophenyl-beta-glucoside is 1.1 x 10 M. The molecular weight of this enzyme is approximately 410,000. Both enzymes have an optimal temperature of 45 degrees C and an E(act) of 9.15 kcal (ca. 3.83 x 10 J). The pH optima, however, were approximately 7.0 and 5.5 for the intracellular and extracellular enzymes, respectively.

Journal Article↗
PubMed1979

Neutralizing antibody to bovine adenovirus serotype 3 in healthy cattle and cattle with respiratory tract disease.

A serosurvey of healthy cattle for the presence of serum-neutralizing antibody to bovine adenovirus serotype 3 (BAV-3) established the widespread prevalence of this agent in Iowa cattle. Of the animals studied, 19.1% (involving 157 calves that represented 40 outbreaks (herds) of respiratory tract disease) seroconverted to BAV-3. This pathogen was implicated serologically as being involved in the cause of respiratory tract disease in six herds. Bovine adenovirus serotype 3 was isolated from cattle in two of these herds. Based on seroconversion and lack of isolation of other viral agents, it appeared that BAV-3 could have been the sole virus involved in the respiratory tract disease in one of these two herds. In another herd, seroconversion was observed only to BAV-3, but other viral agents as well as BAV-3 were isolated. The remaining four herds presented a problem because the cattle seroconverted to more than one agent and additional viral agents were isolated from some animals. Whether the disease manifestations observed in these six herds were due solely or in part to BAV-3 can only be speculated. Cattle are capable of undergoing a natural infection, as indicated by seroconversion, in the absence of overt clinical signs of illness. It appears that maternal (passive) antibody decreases to a point at which infection by this virus becomes possible and an active immune response occurs.

Adenoviridae↗