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Biomedical subjects

M S Morgan

Publications and source records attributed to M S Morgan.

At least 55 records · Page 3Linked to original sources
PubMed1995

Some effects of sarcoptic mange on dogs.

Sequential changes in pathology were examined for scabies-infested dogs to determine the effects of infestation with Sarcoptes scabiei var. canis. During 8 wk of infestation with S. scabiei, the progression of the disease was evaluated weekly by skin scrape, clinical examination, and blood analyses. At 8 wk, selected organs were microscopically examined for histopathology. All infested dogs developed an advanced level of scabies infestation by 8 wk. Of the 36 blood parameters evaluated, only values for erythrocyte sedimentation rate (ESR) deviated significantly from the normal ranges for dogs. However, infested dogs had significantly (P < 0.01) lower average hemoglobin and hematocrit concentrations after 8 wk of infestation compared to their values prior to infestation or to the values for the control dogs. Red blood cell levels for infested dogs dropped significantly (P < 0.01) from preinfestation concentrations by week 8. Conversely, by 8 wk total white blood cell and neutrophil concentrations were significantly (P < 0.01) greater than uninfested controls. Also, whereas average eosinophil concentrations were not statistically different for infested dogs compared to controls, some individual infested dogs exhibited eosinophilia at 4-8 wk of infestation. The ESRs for infested dogs were significantly (P < 0.01) greater at week 6 and 8 than for experimental dogs prior to infestation or control dogs. All parameters except neutrophils had returned to preinfestation levels by 2 wk after treatment for scabies. Neutrophil concentrations were no longer significantly different by 4 wk posttreatment. There were no significant differences in serum enzyme, biochemical and electrolyte concentrations between infested and control dogs.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

English plantain and psyllium: lack of cross-allergenicity by crossed immunoelectrophoresis.

BACKGROUND: English plantain (Plantago lanceolata) weed pollen and psyllium (Plantago ovata) husk dust are inhalant allergens. Because of the phylogenetic relationship between these plant species, cross-allergenicity has been a concern. OBJECTIVE: The purpose of this study was to investigate the possible cross-allergenicity of plantain and psyllium. METHODS: Homologous and heterologous crossed immunoelectrophoresis (CIE) were performed using a commercial English plantain pollen extract and an extract of psyllium seed embryo. Crossed radioimmunoelectrophoresis (CRIE) was performed using sera from subjects who were RAST positive only to plantain (group A), RAST positive only to psyllium (group B), RAST positive to both plantain and psyllium (group C), or RAST negative to both (group D). RESULTS: All of the group A plantain subjects showed IgE binding to at least one of the six plantain allergens in homologous plantain CRIEs while only one of the sera from the group B subjects reacted very weakly to these plantain allergens. In homologous psyllium CRIE, all group B subjects showed pronounced IgE binding to 2 to 7 of the seven psyllium allergens. Several of the plantain subjects demonstrated only very weak binding to psyllium allergens. Heterologous CRIEs demonstrated little relevant IgE binding. CONCLUSIONS: These results indicate that there is little cross-allergenicity between psyllium husk and English plantain pollen.

Allergens↗
PubMed1994

Effects of sulfur dioxide exposure on African-American and Caucasian asthmatics.

There is concern that air pollution may be causing increases in asthma morbidity and mortality, especially among African-Americans. It is possible that there may be ethnic differences in susceptibility. To evaluate this speculation, a comparative pilot study of respiratory function in 10 African American and 12 Caucasian methacholine positive asthmatic males was conducted. Subjects were exposed to pure air or 1 ppm SO2 while breathing inside a polycarbonate head dome, for 10 min of rest and 10 min of exercise. Baseline and postexposure pulmonary function measurements were recorded, and nasal lavage fluid samples were collected and processed for epithelial and white blood counts. Although significant increases were seen in total respiratory resistance following SO2 exposure in both groups (P = 0.04), no ethic-based difference in response was seen. No significant differences were found in pulmonary or nasal measurements after exposure to SO2 between African-American and Caucasian subjects. No significant changes in epithelial or white blood cell count were found either when data were analyzed from the entire group or separately from the two subject groups. Even though there were no significant group changes, some individuals were particularly responsive to SO2. Three Caucasian and 5 African-American subjects showed greater than 20% increases in total respiratory resistance.

Adult↗
PubMed1994

Sarcoptes scabiei: the circulating antibody response and induced immunity to scabies.

Scabies is an important parasitic disease that continues to persist throughout the world despite the availability of acaricides to control it. The immune response mechanism to scabies and the possible development of a vaccine for control of scabies was investigated. This study demonstrated that hosts infested with scabies develop immunity (resistance) to reinfestation. All hosts developed scabies-specific elevated circulating antibody titers during scabies infestations that followed the classical pattern for primary and secondary infestations. Parallel elevated levels of complement C3 were also observed. The hosts that exhibited acquired immunity after their first infestations had antibody and complement levels during challenge infestations lower than those of the hosts that showed no immunity when reinfested. Induction of immunity coupled with generally elevated antibody levels for both immune and nonimmune hosts suggested that resistance to reinfestation was associated with a cell-mediated response. These data also suggested that vaccination with specific scabies tissue containing the relevant antigens or recombinant relevant antigens could enhance the cell-mediated response to protect the hosts against natural infestations.

Animals↗
PubMed1994

Sarcoptes scabiei: histopathological changes associated with acquisition and expression of host immunity to scabies.

The sequential changes in the histology in scabietic lesions were investigated for hosts (rabbits) during sensitization and reinfestation with Sarcoptes scabiei. Experimentally infested naive hosts developed heavy scabies infestations but 65% of the hosts showed induced immunity (resistance) to reinfestation. All hosts (naive, immune, and susceptible) exhibited an initial cell infiltrate in scabietic lesions that consisted predominantly of neutrophils and a few macrophages. This was followed by a dense plasma cell infiltrate. Upon reinfestation the progression of neutrophil infiltration was faster and the response was greater in hosts who acquired immunity than those in the susceptible hosts.

Animals↗
PubMed1994

Comparative analysis of recovery of cardiopulmonary bypass residual blood: cell saver vs. hemoconcentrator.

For surgical bleeding problems, the cell saver has been used to return shed blood; however, overuse can lead to a deficit in coagulation factors. Its usefulness has gained widespread use in many surgical settings. The hemoconcentrator can aid in raising the hematocrit level while reducing blood utilization where large blood volume and/or large amounts of irrigation are returned to the perfusion circuit. The hemoconcentrator returns red blood cells without removing coagulation factors, unlike the cell saver. In order to determine which method of returning residual blood from the cardiopulmonary bypass circuit is more desirable, blood samples were drawn both pre and post transfusion from 15 cell saver patients, and 14 hemoconcentrator patients. Twelve hour blood loss was recorded in 40 patients within each group. The fibrinogen, platelet count, total protein, albumin and white blood cell count were similar between the two groups, as was the blood loss. The only significant differences found were the post red blood cell count, post hemoglobin, and the delta hematocrit, all being higher in autotransfusion group. In conclusion, returning blood through the hemoconcentrator in the average adult perfusion circuit was not able to significantly raise certain coagulation parameters, nor reduce postoperative bleeding.

Blood Coagulation↗
PubMed1994

Serum antibody profiles of Sarcoptes scabiei infested or immunized rabbits.

The circulating antibody profiles of rabbits infected or immunized with Sarcoptes scabiei var. canis were compared. Crossed immuno-electrophoretic analysis showed that infested hosts produced serum antibody to 12 proteins (antigens) in an extract made from sarcoptic mite bodies. In contrast, rabbits immunized with an extract made from mite bodies produced antibody to 20 Sarcoptes proteins (antigens). SDS-PAGE/immunoblot analysis revealed that serum from immunized rabbits contained antibodies that bound strongly to proteins of 25 and 39-52 kD that were only barely visualized by antibodies in serum from infested rabbits.

Animals↗
PubMed1993

Evaluation of stable isotope-labeled probes in the study of solvent pharmacokinetics in human subjects.

The relationship between biomarkers of exposure (such as concentrations of toxicants in blood or breath, or metabolites in urine) and toxicant dose for individuals is influenced by many person- and episode-specific factors which contribute to overall variability in biomarker level for a given dose. This variability results in imprecise biological marker-based estimates of dose for individuals. We hypothesize that pharmacokinetic data from stable-isotope (deuterated) analogs can be used with a pharmacokinetic model to account for individual-related sources of variation, leading to more precise methods of dose estimation for individuals. To establish the degree of similarity in the pharmacokinetics of unlabeled (d0-) and fully deuterated (D8-) toluene, 21 men (ages 20-45) inhaled an equal molar mixture for 2h. Washout kinetics for both compounds were followed for 4 d in alveolar air and blood. Both compounds exhibited three-phase elimination kinetics in both fluids. The third phase was not always definable for d0-toluene because of concurrent uncontrolled environmental exposures. Considering data from only the first two phases, concentrations of d0- and d8-toluene in alveolar air and blood were well correlated for all subjects, even though pharmacokinetic parameters varied among individuals by 5-9 folds. Further experiments are needed to discern whether correlations between d0- and d8-toluene for the third phase are influenced by an isotope effect; present data support use of d8-toluene as a suitable probe for d0-kinetics.

Adult↗
PubMed1992

A study of the cardiac effects of bromochlorodifluoromethane (halon 1211) exposure during exercise.

Bromochlorodifluoromethane (halon 1211, a fire extinguisher), like other fluorocarbons, has been linked with ventricular arrhythmias and myocardial depression. Ten healthy firefighters, aged 40-50, were exposed to 1,000 ppm halon while exercising, in a double-blind, placebo-controlled crossover experiment, and were monitored during and after exposure. Complex ectopy (ventricular couplets and idioventricular rhythm) occurred in two subjects with halon, but none with placebo. One subject had 49.5 ventricular premature beats (VPB)/hour during the period of halon exposure and subsequent 8 hours and only 8.7 VPB/hour during the same period of placebo. In addition, 8 of the 10 subjects had a smaller systolic blood pressure rise during exercise with halon than with placebo. None of the observed differences was statistically significant. These results are consistent with findings in other investigations, suggesting that occupational fluorocarbon exposures may be cardiotoxic in certain individuals, although the small sample sizes used in this and other studies have resulted in limited statistical power to demonstrate this effect.

Adult↗
PubMed1992

A case-control study of occupational risk factors for laryngeal cancer.

To determine whether specific jobs and occupational exposures are associated with laryngeal cancer lifetime occupational histories from a population-based case-control study in western Washington were examined. The study included 235 cases diagnosed between September 1983 and February 1987, and 547 controls identified by random digit dialing. After controlling for alcohol use, cigarette smoking, age and education, significantly increased risks were found for painters in construction (odds ratio (OR)) = 2.8, (95% confidence interval (95% CI) 1.1-6.9), supervisors and miscellaneous mechanics (OR = 2.3, 95% CI 1.1-4.8), construction workers (OR = 3.4, 95% CI 1.4-8.1), metalworking and plastic working machine operators (OR = 2.6, 95% CI 1.3-4.9) and handlers, and equipment cleaners and labourers (OR = 1.5, 95% CI 1.0-2.2). Allowing for a 10 year induction and latent period did not have a consistent effect on the associations. Potential exposures to asbestos, chromium, nickel, formaldehyde, diesel fumes, and cutting oils were assessed by using a job exposure matrix developed for this study. Three measures of exposure were examined--namely, peak, duration, and an intensity weighted exposure score. No significantly raised risks were seen, although increased risk was suggested among those exposed long term to formaldehyde in jobs with the highest exposures.

Adult↗
PubMed1991

Correlation of preoperative factors, severity of disease, type of oxygenator and perfusion times with mortality and morbidity of coronary bypass.

Previous studies have related preoperative status and severity of disease to the outcome of coronary artery bypass surgery. Although increased perfusion and clamp times increase the risk of cardiac surgical procedures, the importance of these factors in relation to the patient's preoperative condition and the severity of disease has not previously been determined. In this study of 1078 patients, we examined the correlation between the patient's preoperative condition, the severity of coronary disease, and duration of perfusion and clamp time, and the type of oxygenator used with the mortality and morbidity associated with coronary artery bypass grafting. One-way analysis of variance and multiple correlation analysis showed that perfusion time, clamp time and nonclamp perfusion time correlated with mortality, perioperative infarction, the use of intra-aortic balloon pump, stroke, renal failure, pulmonary failure, infection, and leg wound complications (p less than 0.05). Perfusion time, clamp time and nonclamp perfusion time did not correlate with postoperative bleeding or sternal wound complications. Nonclamp perfusion time correlated more strongly than any other factor with mortality, perioperative infarction, the use of intra-aortic balloon pump, renal failure, pulmonary failure and infection (p less than 0.05). Clamp time correlated more than any other factor with the development of leg-wound complications (p less than 0.05). The use of a bubble rather than a membrane oxygenator was significantly related to mortality, stroke, infection and leg wound complications by one-way analysis of variance (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Carbon monoxide and oxygen binding to human hemoglobin F0.

Differential binding curve measurements of carbon monoxide and oxygen binding to human hemoglobin F0 under near-physiological conditions (0.1 M NaCl and 15 mM 2,3-diphosphoglyceric acid, pH 7.35, and 37 degrees C) have allowed a detailed description of the binding and linkage between these two gaseous ligands. Comparison with human hemoglobin A0 under identical solution conditions shows that fetal hemoglobin F0 binds oxygen and carbon monoxide with higher affinity than human hemoglobin A0, but with the same cooperativity. Construction of the partition coefficient surface for carbon monoxide and oxygen binding reveals a failure of Haldane's laws for both hemoglobins. Linkage graphs are used to explore the phenomenological properties of the system. The graphs provide a quantitative description of the mechanism of carbon monoxide toxicity on oxygen transport by hemoglobin in vivo and demonstrate striking similarities between the functional properties of fetal and adult hemoglobins.

Carbon Monoxide↗