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Biomedical subjects

M Davidson

Publications and source records attributed to M Davidson.

At least 415 records · Page 23Linked to original sources
PubMed1966

The interaction of mycoplasmas with mammalian cells. II. Monocytes and lymphocytes.

The incubation of mycoplasmas with human peripheral blood buffy coats resulted in the uptake of these microorganisms by more than 50% of the mononuclear cells. Mycoplasmas adhered to the plasma membranes of all leukocytes, most of which developed long cytoplasmic processes not seen in the controls. In human and rat thoracic duct lymph, about 6% of the cells ingested the microorganisms. T(2) phage and thorotrast were taken up by a similar percentage of lymphocytes. On morphological grounds, the cells which were able to take up PPLO's or particles could not be distinguished from the cells which were incapable of this function. Following phagocytosis, neither the cell nor the microorganism showed any morphological alterations over a 3 hr period of observation. The demonstration that a small percentage of "lymphocytes" are able to phagocytose may have pathological and immunological implications.

Animals↗
PubMed1966

Studies of PPLO infection. I. The production of cerebral polyarteritis by Mycoplasma gallisepticum in turkeys; the neurotoxic property of the Mycoplasma.

Turkey poults injected intravenously with suspensions of Mycoplasma gallisepticum develop a fatal neurologic disease associated with polyarteritis affecting almost exclusively the cerebral arteries. The incubation period depends on the dose of organisms. With high doses (10(10) to 10(11) mycoplasmas) the birds become ill and die within a few hours; with lower doses (10(6) to 10(8)) neurologic manifestations appear after 7 days. The rapid onset of neurologic signs after high doses indicates the presence of a toxin in the mycoplasma, but efforts to extract toxin from disrupted organisms or to demonstrate its presence in culture fluid free of mycoplasmas have been unsuccessful. The toxin appears to be associated only with living mycoplasmas. The toxic component of M. gallisepticum is inactivated by heating the organisms at 50 degrees C, disruption by repeated cycles of freezing and thawing, and exposure to specific antibody. Treatment of turkeys with gold thiomalate furnishes partial protection against the toxic effects of large doses of mycoplasmas, and protection against the development of cerebral arteritis. Treatment with tetracycline protects completely against both toxicity and arteritis, and, when delayed, restores diseased birds to a healthy state. Cortisone, methotrexate and 6-mercaptopurine have no effect on the course or outcome of the disease. Intracerebral injections of M. gallisepticum are less toxic and lethal than when the same dose was given by vein, indicating that the organism exerts its damaging action on blood vessels by way of the blood stream. The arterial lesions resemble those of serum sickness, except for their distribution, and are associated with glomerular inflammatory lesions. However, for various reasons discussed, it is considered more likely that they result from a direct toxic action of living mycoplasmas on the vessels concerned than from an immunologic mechanism.

Animals↗
PubMedDate not supplied

Efficacy and safety of an over-the-counter transdermal nicotine patch as an aid for smoking cessation.

OBJECTIVE: To evaluate the efficacy and safety of a transdermal nicotine patch as an aid for smoking cessation in an over-the-counter setting. DESIGN: Multicenter, double-blind, randomized, placebo-controlled trial of 6-week duration with 18 weeks of follow-up. SETTING: Four shopping mall precincts. PARTICIPANTS: The randomized sample consisted of 802 adults (mean age, 39 years) and was 89% white and 54% female. A smoking history of at least 20 cigarettes per day for 1 year and a score of 5 (on a 10-point scale) on a motivational assessment questionnaire were required for enrollment. Poststudy follow-up was limited to those who had quit smoking at the end of 6 weeks. INTERVENTION: Nicotine patches were provided at the shopping mall. Guidance consisted only of package instructions and a smoking cessation self-help booklet. MAIN OUTCOME MEASURES: Quit rates were defined as total abstinence from smoking for 4 consecutive weeks (treatment weeks 3-6), point prevalence smoking status at week 6, or nonsmoker at week 6 and week 24 (6-month postquit date). Smoking status was assessed by diaries, and verification for the first 2 quit rates was obtained by confirmation of carbon monoxide of 8 ppm or less in expired breath. Safety was evaluated by self-reported adverse events. RESULTS: Quit rate was 12% for the active treatment group and 5.5% for the placebo group, based on total abstinence for 4 consecutive weeks (P = .001) compared with quit rates of 19.5% and 7.5% for active treatment and placebo groups, respectively, based on point prevalence data at week 6. At 24 weeks, 8.2% of nonsmokers in the active treatment group and 4.0% in the placebo group remained nonsmokers. At least 1 adverse event was reported by 57% receiving the nicotine patch and 39% receiving placebo (P<.001). CONCLUSIONS: When the nicotine patch was used in an over-the-counter setting, quit rates were comparable to those reported for medical settings. A 2:1 quit rate advantage was achieved at week 6 and was maintained at 24 weeks.

Administration, Cutaneous↗
PubMedDate not supplied

Platelet phospholipid synthesis in Alzheimer's disease.

The rates of incorporation of [3H]choline and [3H]ethanolamine into membrane phospholipids of platelets from 22 drug-free Alzheimer's disease patients and 18 normal elderly controls were compared. No significant differences between groups were found. If alterations in lipid metabolism are involved in the pathophysiological processes underlying Alzheimer's disease, such alterations are not manifest in measures of radiolabeled base incorporation into platelet phospholipids.

Aged↗
PubMedDate not supplied

Group G streptococcal meningitis and sepsis in a patient with AIDS. A method to biotype group G streptococcus.

Lancefield group G streptococcus is now recognized as a pathogen and has been reported to cause severe infections, including meningitis. We describe the first case of meningitis caused by this organism in a patient with acquired immunodeficiency syndrome (AIDS) and the direct transmission of the pathogen to a technologist accidentally exposed to the cerebrospinal fluid. To prove the identity of the two strains, we have tested them employing the Vitek system. We have also tested 13 other strains of group G streptococci obtained from different sources. Our results yielded 14 different biotypes with the 15 strains tested. The only identical ones were the two suspect strains from the index case and the technologist. We conclude that the biotyping system employed in our study appears to be a useful epidemiological tool for marking group G streptococci.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Diagnostic issues in chronic schizophrenia: kraepelinian schizophrenia, undifferentiated schizophrenia, and state-independent negative symptoms.

Data are presented concerning three recent clinical distinctions in schizophrenia: kraepelinian versus non-kraepelinian patients; mixed versus simple undifferentiated subtypes; and state-dependent versus state-independent negative symptoms. Schizophrenic patients who have been ill and dependent on others for the past 5 years ('kraepelinians') were compared to other chronic schizophrenics. The kraepelinian patients met the criteria for schizophrenia by more diagnostic systems than other patients, were less responsive to haloperidol, had more severe negative symptoms and formal thought disorder, and had similarly severe positive symptoms. They also had cerebral ventricles that demonstrated more left-to-right asymmetry and a greater family history of schizophrenia spectrum disorders. Mixed undifferentiated schizophrenic patients, who met criteria for more than one schizophrenic subtype, were compared to simple undifferentiated schizophrenic patients, who met criteria for no subtype. The mixed group was characterized by more severe positive and negative symptoms and formal thought disorder, worse social functioning, and a worse response to haloperidol. In a subgroup of patients who were studied once while in a state of exacerbation and once while in a state of relative remission, the negative symptoms of inattention and affective flattening were state-dependent, while anhedonia-asociality was state-independent.

Adult↗
PubMedDate not supplied

Acute administration of alprazolam has no effect on plasma homovanillic acid concentration in normal subjects.

Alprazolam has been suggested as an adjuvant to neuroleptic drugs in the treatment of schizophrenic patients. In an attempt to investigate whether alprazolam has an effect on dopaminergic neurotransmission, plasma homovanillic acid concentrations were measured for 24 h following a challenge with 3 mg of alprazolam or placebo in eight healthy subjects. Alprazolam had no effect on plasma homovanillic acid which may suggest that this agent is devoid of activity at the dopaminergic system in normal subjects.

Administration, Oral↗
PubMedDate not supplied

The lipid-lowering effects of atorvastatin, a new HMG-CoA reductase inhibitor: results of a randomized, double-masked study.

This randomized, placebo-controlled, double-masked, parallel-group trial assessed the serum cholesterol-lowering effects of atorvastatin, a new 3-hydroxy-3-methylglutaryl coenzyme. A reductase inhibitor, over 26 weeks in patients with primary hypercholesterolemia. Thirty-nine patients from four centers in the United States were originally randomized to one of two treatment groups and received either atorvastatin 10 mg (20 patients) or placebo (19 patients) once daily. Atorvastatin rapidly and significantly reduced serum total cholesterol, low-density lipoprotein cholesterol (LDL-C), and apolipoprotein B levels. LDL-C was reduced 35% with atorvastatin 10 mg compared with a 0% increase in LDL-C in the placebo group. Atorvastatin significantly reduced triglyceride levels, with improvements occurring over time. At 26 weeks, triglyceride levels were reduced by 21% with atorvastatin treatment compared with a 14% increase with placebo. The drug was well tolerated and no clinically significant laboratory abnormalities were detected.

Adult↗
PubMedDate not supplied

Ethanol inhibition of brain ornithine decarboxylase activity in the postnatal rat.

The purpose of this study was to determine the relationship between ornithine decarboxylase activity (ODC; a marker for perturbed cell development), the blood alcohol level, and alcohol-induced microencephaly in the developing rat brain after binge treatment with ethanol vapour. By manipulating ethanol flow we were able to adjust vapour concentrations (24-65 mg ethanol/l air) such that an acute exposure of ethanol vapour for 3 h resulted in a range of blood alcohol levels (2.3-5.5 mg/ml). Acute studies showed that ethanol dose-dependently inhibited rat hippocampal and cerebellar ODC activity at PND4-PND10. There was a significant correlation between the blood alcohol level and degree of inhibition at all ages tested. Chronic treatment from PND4 to PND9 caused a significant decrease in both brain to body weight ratio and in hippocampal and cerebellar ODC activities at PND10. These results indicate that ethanol-induced disruption in ODC could play a significant role in ethanol's teratogenic effects during early postnatal development.

Animals↗
PubMedDate not supplied

Germline mutational analysis of presenilin 1 and APP genes in Jewish-Israeli individuals with familial or early-onset Alzheimer disease using denaturing gradient gel electrophoresis (DGGE).

Germ line mutations in three genes have been detected in patients with familial Alzheimer's disease (FAD) and sporadic, early onset disease: amyloid precursor protein (APP), presenilin 1 (PS-1), and presenilin 2 (PS-2). The relative proportions in which mutations in these genes occur among AD patients in Israel has not been evaluated. To that end, we screened 52 Jewish-Israeli patients with AD: 22 with sporadic, early-onset disease (below 65 years), and 30 with FAD. Mutation screen employed denaturing gradient gel electrophoresis (DGGE) of exon-specific PCRs and restriction enzyme digest. Five patients from three different families displayed mutations within the PS-1 gene: three patients of one family showed a mis-sense mutation in codon 120 (Glu 120Lys), and two other unrelated patients showed an identical mis-sense mutation in codon 318 (Glu318Gly). No patient showed an abnormal migration on DGGE (for APP) or mutant restriction digest pattern (for PS-2) genes. These data may indicate the existence of another familial Alzheimer disease (FAD) gene locus in the Israeli Jewish population.

Adult↗
PubMedDate not supplied

Teaching teens to cope: coping skills training for adolescents with insulin-dependent diabetes mellitus.

PURPOSE: To review the potential use and application of coping-skills training in teaching adolescents effective ways of managing the stressors related to living with diabetes mellitus. POPULATION: Adolescents ages 13 to 20 with insulin-dependent diabetes mellitus who are participating in the research project, "Nursing Intervention to Implement DCCT Therapy in Youth" at Yale University School of Nursing. CONCLUSIONS: Teaching adolescents with diabetes mellitus to use appropriate coping skills may help them cope with the day-to-day management of the illness and aid in long-term adaptation. PRACTICE IMPLICATIONS: Research has suggested that the use of effective coping skills may aid in healthy long-term adaptation to diabetes mellitus. Thus, nurses caring for adolescents with this illness should teach and be role models for these effective coping strategies.

Adaptation, Psychological↗
PubMedDate not supplied

No excess of factor V:Q506 genotype but high prevalence of anticardiolipin antibodies without antiendothelial cell antibodies in retinal vein occlusion in young patients.

Factor V:Q506 (factor V Leiden) is associated with venous thrombosis and has been reported to be a risk factor for retinal vein occlusion (RVO). Anticardiolipin antibodies (ACA), also associated with RVO, are a marker for the prothrombotic condition antiphospholipid syndrome, in which antiendothelial antibodies (AECA) are also frequently present. This study reviewed 45 younger patients 10 GPL units); in 6 of these, the titre was >20 GPL units (population reference range = 0-10 GPL units). No patient had antiendothelial cell reactivity. The low-titre ACA may therefore represent a non-specific response to vascular injury.

Activated Protein C Resistance↗
PubMedDate not supplied

A pilot study of clonidine plus physostigmine in Alzheimer's disease.

To assess the feasibility of one approach to combined cholinergic/noradrenergic treatment in Alzheimer's disease, ten patients were enrolled in a 2-week placebo-controlled study of oral physostigmine plus clonidine. The Alzheimer's Disease Assessment Scale (ADAS) was used as the primary outcome measure. Neither physostigmine alone, nor the combination of physostigmine plus clonidine, was associated with a statistically significant improvement for the group. Three patients did show an improvement of at least 4 points on the total ADAS score with the drug combination. The implications of these results for treatment strategies are discussed.

Aged↗