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Biomedical subjects

C Fletcher

Publications and source records attributed to C Fletcher.

At least 91 records · Page 5Linked to original sources
PubMed1986

Brugia pahangi infections in cats: antibody responses which correlate with the change from the microfilaraemic to the amicrofilaraemic state.

The humoral responses of eight cats infected with Brugia pahangi to somatic antigens from all life-cycle stages were examined quantitatively by ELISA and qualitatively by immunoblotting for almost a year post infection. Six cats spontaneously became amicrofilaraemic: their production of IgG antibodies against somatic antigens of microfilariae, adults, and infective larvae was not statistically higher than that of the two cats which remained microfilaraemic. However, immunoblotting revealed that those cats which spontaneously became amicrofilaraemic selectively recognized certain microfilarial, adult and infective larval somatic antigens prior to disappearance of microfilariae from the peripheral circulation. The data suggest that selective recognition of antigens by some cats is responsible for the production of antibodies which may then promote microfilarial death.

Animals↗
PubMed1986

In vitro comparison of antiplatelet effects of beta-lactam penicillins.

beta-Lactam antibiotics have been shown to cause platelet dysfunction and bleeding in some patients. However, relative antiplatelet activity of various beta-lactams has remained controversial. Results of clinical studies have been variable because of the presence of underlying disease in the study patients, in addition to inherent difficulties of in vivo experimentation such as individual variations of drug metabolism and drug kinetics. Thus, we designed in vitro experiments to study the direct effect of penicillin G, carbenicillin, ticarcillin, mezlocillin, piperacillin, nafcillin, and azlocillin on platelets. Platelets obtained from normal volunteers were exposed in vitro for 15 minutes to increasing concentrations of the test penicillins (10.0, 12.5, 15.0, and 20.0 mmol/L), and the platelet aggregation response determined after the additional of adenosine diphosphate (2.5 to 5.0 mumol/L), epinephrine (0.1 X 10(-3) mol/L), thrombin (0.01 to 0.02 U/ml), and collagen (11.62 micrograms/ml). All tested penicillins inhibited platelet aggregation in a saturable dose-dependent manner that was reversible by platelet washing. Biostatistical comparison of inhibition of platelet aggregation demonstrated nafcillin to cause significantly more inhibition, followed by azlocillin, mezlocillin, and piperacillin as a group. Penicillin G, carbenicillin, and ticarcillin were the least inhibitory. The mean percent inhibition (epinephrine) at 20 mmol/L concentration was nafcillin 86.4%, mezlocillin 83.2%, piperacillin 80.3%, azlocillin 76.4%, ticarcillin 73.2%, carbenicillin 66.4%, and penicillin G 58.4% (overall P less than 0.001). We conclude that all penicillins tested in vitro inhibit platelet aggregation in normal individuals, but to varying degrees. The inhibitory response, which is most likely a membrane-related phenomenon, is dose dependent and reversible.

Adenosine Diphosphate↗
PubMed1985

Schistosoma mansoni: reduced efficacy of chemotherapy in infected T-cell-deprived mice.

The effect of host immunosuppression on the efficacy of schistosomicidal chemotherapy has been tested in T-cell-deprived CBA mice infected with Schistosoma mansoni. The drugs hycanthone, oxamniquine, and praziquantel were found to kill fewer adult S. mansoni worms in deprived mice than in comparably infected strain-, age-, and sex-matched, immunologically intact controls. Inconsistent results were obtained with niridazole, and amoscanate was as effective in deprived mice as in controls. The possibility that hycanthone, oxamniquine, praziquantel, and previously studied antimony act synergistically with immune effector mechanisms in killing adult schistosomes is discussed.

Animals↗
PubMed1985

Reversal of rest myocardial asynergy during exercise: a radionuclide scintigraphic study.

UNLABELLED: While exercise-induced segmental left ventricular wall motion abnormalities are well described, the phenomenon of improvement in certain asynergic segments during exercise in some patients remains a curiosity. To assess this unexpected finding, results were analyzed in 85 patients with wall motion abnormalities at rest who underwent two view (45 degrees left anterior oblique and anterior) exercise radionuclide ventriculography and exercise thallium-201 myocardial perfusion imaging. Wall motion was scored with a 5 point system (from 3 [normal] to - 1 [dyskinesia]); normalization or increase of 2 or more points with exercise signified improvement. Forty-eight patients (56%) had no change or further deterioration of wall motion at peak exercise, 15 (18%) showed both improvement of wall motion and deterioration and 22 (26%) showed only improvement of wall motion. Wall motion improvement during exercise was found in 57 (20%) of 279 segments with asynergy at rest. Of these 57 segments improving with exercise, 45 (79%) showed mild and 12 (21%) showed severe asynergy at rest. Only seven segments (12%) were associated with pathologic Q waves. Thallium-201 perfusion was normal in 44 segments (77%) while only 6 segments (11%) had reversible and only 7 (12%) had nonreversible thallium-201 defects. IN CONCLUSION: 1) wall motion that is abnormal at rest can sometimes improve with exercise; 2) this phenomenon generally occurs in zones without a Q wave or nonreversible thallium-201 defect. Hence, segments with abnormal wall motion at rest that show improvement with exercise appear to represent viable nonischemic segments.

Adult↗
PubMed1977

The natural history of chronic airflow obstruction.

A prospective epidemiological study of the early stages of the development of chronic obstructive pulmonary disease was performed on London working men. The findings showed that forced expiratory volume in one second (FEV1) falls gradually over a lifetime, but in most non-smokers and many smokers clinically significant airflow obstruction never develops. In susceptible people, however, smoking causes irreversible obstructive changes. If a susceptible smoker stops smoking he will not recover his lung function, but the average further rates of loss of FEV1 will revert to normal. Therefore, severe or fatal obstructive lung disease could be prevented by screening smokers' lung function in early middle age if those with reduced function could be induced to stop smoking. Infective processes and chronic mucus hypersecretion do not cause chronic airflow obstruction to progress more rapidly. There are thus two largely unrelated disease processes, chronic airflow obstruction and the hypersecretory disorder (including infective processes).

Adult↗
PubMed1975

Vocational potential assessment.

Determination of employment potential will become increasingly important in the foreseeable future, largely due to pending Federal legislation which relates to welfare reform. The heretofore "permanently and totally disabled versus able-bodied" principle in welfare reforms is being abbandoned. Pending legislative proposals dealing with welfare reform provide for considering physically impaired persons as partially disabled and partially employable simultaneously. Thus, the need to systematically and effectively assess physically impaired citizens' capacities to participate in the job market will increase. Unquestionably, rehabilitation medicine in general, and the emerging art and science of vocational evaluation in particular, will contribute much to supplying these services. While it is widely acknowledged that the vocational potential of physically impaired persons should be evaluated in an organized manner, there are differences of opinion among professional evaluators as to which approach, or approaches, are the most meritorious; The four principal approaches are: (1) mental testing, (2) work sampling, (3) situational analysis, and (4) job tryouts. Each of these approaches is explained, contrasted, and evaluated in this paper.

Disability Evaluation↗