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Biomedical subjects

M Davidson

Publications and source records attributed to M Davidson.

At least 235 records · Page 13Linked to original sources
PubMed1992

Assessment of dementia in elderly schizophrenics with structured rating scales.

Although a number of elderly institutionalized schizophrenic patients appear to suffer from dementia, little is known about the characteristics of the cognitive impairment or its prevalence in this population. In order to answer these questions it is necessary to first reliably and validly assess dementia in elderly schizophrenic patients. This paper reports the results of a study examining the reliability of assessments of the severity of dementia in schizophrenia using scales designed for other dementing conditions and examining the convergence of ratings of the severity of dementia generated from all available sources of information (patient, caregiver, and chart) versus the chart alone. It was found that the interrater reliability of these ratings was very high. On the other hand ratings generated from the hospital chart alone, without contact with either the patient or caregiver, manifested a systematic bias toward overestimation of the severity of dementia. These results suggest that dementia assessment in schizophrenia does not require different instrumentation from that used in other conditions but that relying on the medical chart alone would induce a systematic bias in the results.

Activities of Daily Living↗
PubMed1992

Homovanillic acid measurement in clinical research: a review of methodology.

Despite its serious limitations, measuring the concentrations of homovanillic acid (HVA) in body fluids is perhaps the most direct method currently available to assess the changing activity of central dopamine (DA) neurons in living humans. The concentrations of HVA in body fluids are determined not only by the activity of central DA neurons but also by a number of unrelated factors such as the other sources of HVA and the elimination of HVA from the body. This article reviews many factors that help to determine the concentrations of HVA in body fluids and therefore must be considered in studies employing HVA as a possible index of central DA neuronal activity. The need for further methodological work is indicated to improve the use of body fluid HVA measurements in clinical research.

Body Fluids↗
PubMed1992

Quantitation of pneumococcal C polysaccharide in sputum samples from patients with presumptive pneumococcal pneumonia by enzyme immunoassay.

Although the Gram stain and culture of expectorated sputum are considered standard methods for the diagnosis of presumptive pneumococcal pneumonia, these methods remain relatively insensitive and nonspecific. We developed an enzyme immunoassay (EIA) for the quantitation of pneumococcal C polysaccharide (PnC) in the sputum of patients with presumptive pneumococcal pneumonia. Of 34 patient sputum samples collected within 24 h of the first radiographic report of pneumonia, 12 grew Streptococcus pneumoniae on culture. By using a cutoff point of 0.5 micrograms of PnC per ml of sputum, all 12 specimens were positive (sensitivity, 100%) by EIA. PnC levels ranged from 1.43 to 57.53 micrograms/ml. Blood samples from 18 of the 34 patients were cultured. S. pneumoniae grew in the culture of a blood sample from one patient, whose sputum also had the highest PnC level. Of 22 sputum samples from patients with pneumonia that did not grow S. pneumonia, two were positive by EIA (specificity, 90.1%). Sputa from both patients had low levels of PnC (2.7 and 4.5 micrograms/ml), and both patients had received antibiotics before sputum collection. The positive predictive value of the quantitative EIA was 85.7%. Quantitation of PnC has the potential for improving the accuracy of sputum examination for S. pneumoniae, monitoring disease severity and the effectiveness of antibiotic therapy, and differentiating between those patients with invasive pneumococcal disease and those who are carriers of S. pneumoniae.

Bacteriological Techniques↗
PubMed1992

Defects in mitochondrial protein synthesis and respiratory chain activity segregate with the tRNA(Leu(UUR)) mutation associated with mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes.

Cytoplasts from two unrelated patients with MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis, and strokelike episodes) harboring an A----G transition at nucleotide position 3243 in the tRNA(Leu(UUR)) gene of the mitochondrial genome were fused with human cells lacking endogenous mitochondrial DNA (mtDNA) (rho 0 cells). Selected cybrid lines, containing less than 15 or greater than or equal to 95% mutated genomes, were examined for differences in genetic, biochemical, and morphological characteristics. Cybrids containing greater than or equal to 95% mutant mtDNA, but not those containing normal mtDNA, exhibited decreases in the rates of synthesis and in the steady-state levels of the mitochondrial translation products. In addition, NADH dehydrogenase subunit 1 (ND 1) exhibited a slightly altered mobility on polyacrylamide gel electrophoresis. The mutation also correlated with a severe respiratory chain deficiency. A small but consistent increase in the steady-state levels of an RNA transcript corresponding to 16S rRNA + tRNA(Leu(UUR)) + ND 1 genes was detected. However, there was no evidence of major errors in processing of the heavy-strand-encoded transcripts or of altered steady-state levels or ratios of mitochondrial rRNAs or mRNAs. These results provide evidence for a direct relationship between the tRNALeu(UUR) mutation and the pathogenesis of this mitochondrial disease.

Acidosis, Lactic↗
PubMed1992

Effect of marine lipids on cholesteryl ester transfer and lipoprotein composition in patients with hypercholesterolemia.

While the effects of omega-3 (n-3) fatty acids present in marine lipids on plasma lipoprotein levels have been intensively studied, less is known about their impact on reverse cholesterol transport. For this reason, for a 3-month period we studied the effects of the administration of n-3 fatty acids (6 g/day) as a dietary supplement on cholesteryl ester transfer (CET), a key step in this process, and lipoprotein composition in 12 outpatients with genetically heterogeneous forms of hypercholesterolemia. Before treatment, CET in hypercholesterolemic patients, estimated as the mass of cholesteryl ester (CE) transferred from high density lipoprotein (HDL) to very low density lipoprotein (VLDL) plus low density lipoprotein (LDL), was markedly accelerated, peaking after only 1-2 hours of incubation of whole plasma; this response differed significantly (p < 0.001) from the initial delayed curvilinear response of control subjects. Consistent with the accelerated CET occurring in vivo, their triglyceride to esterified cholesterol core lipid ratio before treatment was reduced in the intact VLDL fraction and VLDL1 but not in VLDL2 or VLDL3 and was reciprocally increased in HDL. In addition, the free (unesterified) cholesterol to lecithin ratio of VLDL1 was abnormally increased. Recombination experiments performed with individual lipoprotein fractions revealed that accelerated CET was specifically associated with the VLDL1 subfraction and not LDL, HDL, and cholesteryl ester transfer protein (CETP), although pretreatment levels of CETP were significantly increased (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Agitation and postdexamethasone cortisol levels in Alzheimer's disease.

The clinical correlates of hypothalamic-pituitary-adrenal (HPA) functioning were examined in 29 patients with probable Alzheimer's disease. The 8:00 a.m. postdexamethasone cortisol levels of these patients were highly correlated with higher agitation scores but not with the degree of depressed mood or memory impairment. The possible neural basis for the association between hypercortisolism and behavioral disturbance in Alzheimer's disease warrants further exploration and replication.

Alzheimer Disease↗
PubMed1992

Multidrug resistant Mycobacterium tuberculosis in patients with human immunodeficiency virus infection.

Multidrug resistant Mycobacterium tuberculosis (MDR-MTB) infection has not been recognized as a serious problem in patients with human immunodeficiency virus (HIV) infection. Multidrug resistance (MDR) has appeared in our medical center in 24 out of 72 patients between January 1990 and May 1991 compared to 8 out of 132 patients within the period from 1982 to 1987 (relative risk 5.50 with 95 percent confidence interval 2.61 to 11.61). We describe 19 patients with MDR in MTB (isoniazid and at least one additional first line drug), who had serologic evidence of HIV infection, 13 of whom were diagnosed with acquired immunodeficiency syndrome (AIDS). The MTB cultures from 10 out of 19 patients with MDR were resistant to three or more drugs. Fifteen patients died although 9 out of these 15 had received at least a four-drug regimen for a mean time of seven weeks (range 2 to 12). This increase in MDR was seen in ten homosexuals and nine intravenous drug users. This rapid appearance of MDR-MTB strains is worrisome. New strategies for empiric therapy of such patients while awaiting sensitivity data are needed.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Pneumococcal endocarditis in Alaska natives. A population-based experience, 1978 through 1990.

BACKGROUND: Streptococcus pneumoniae is an uncommon cause of infective endocarditis (IE). We studied the presentation, microbiologic characteristics, and outcome of nine cases of S pneumoniae IE during a 12 1/2-year period in a population of 75,000 indigenous Alaska Natives (ANs), who have documented high rates of invasive pneumococcal disease. METHODS: Fifty-six cases of IE occurred in ANs statewide during 1978 through 1990. Medical records of all nine confirmed cases of S pneumoniae IE were reviewed. Incidence rates for S pneumoniae IE and all IE were calculated. RESULTS: Alaska Natives experience S pneumoniae IE as a fulminant illness, with acute aortic valve insufficiency (100%) frequently requiring emergent valve replacement, S pneumoniae meningitis (56%), and death (33%). No patient with S pneumoniae IE had known preexisting heart disease, and the most common underlying disease was alcoholism (56%). Pneumonia was diagnosed and embolic complications were suspected in 33%. All five S pneumoniae isolates examined were penicillin sensitive and were of serotypes included in the pneumococcal vaccine. Pneumococcal IE accounted for 15.8% of all IE diagnosed in ANs. Age- and sex-adjusted incidence rates for IE of all causes and S pneumoniae IE were 8.5 and 1.5 per 10(5) persons per year, respectively. During 1986 through 1988, 4.3% of AN adults diagnosed with S pneumoniae bacteremia developed S pneumoniae IE. CONCLUSIONS: Pneumococcal endocarditis in all but one AN case required emergent valve replacement and had a 33% mortality. The annual incidence rate of S pneumoniae IE in this population was five to 37 times higher than contemporary rates elsewhere. Increased efforts to prevent pneumococcal disease in ANs appear warranted. Clinicians everywhere should anticipate the possible development of S pneumoniae IE in adult patients with pneumococcal sepsis, especially with meningitis, even with previous vaccination and prompt adequate antimicrobial therapy.

Age Factors↗
PubMed1991

Changes in plasma homovanillic acid concentrations in schizophrenic patients following neuroleptic discontinuation.

Changes in plasma levels of the dopamine metabolite homovanillic acid have been reported to correlate with changes in the severity of schizophrenic symptoms during neuroleptic administration and after neuroleptic discontinuation. This study examined the effects of discontinuation of neuroleptic treatment on plasma homovanillic acid levels in 23 patients with chronic schizophrenia. It was hypothesized that clinical decompensation would be associated with increased plasma homovanillic acid levels. Plasma homovanillic acid was measured during administration of neuroleptic medication and during a subsequent 6-week drug-free period. Nine patients decompensated during the drug-free period and 14 patients did not. Following drug discontinuation, plasma homovanillic acid concentrations were higher in schizophrenic patients who decompensated than in those who did not. Furthermore, peak plasma homovanillic acid elevation after discontinuation of neuroleptic medication was significantly correlated with peak Brief Psychiatric Rating Scale increase. The data suggest that, in some schizophrenic patients, symptomatic decompensation after discontinuation of neuroleptic treatment is associated with increases in dopamine turnover.

Adult↗
PubMed1991

Effects of neuroleptic treatment on symptoms of schizophrenia and plasma homovanillic acid concentrations.

Measurement of plasma concentrations of the dopamine metabolite, homovanillic acid, is an indirect tool to assess changes in dopamine turnover in schizophrenic patients. Plasma homovanillic acid concentrations have been reported to decrease during neuroleptic treatment, with the decrement correlating with symptomatic improvement in symptoms of schizophrenia. The present study tested the hypothesis that neuroleptic drugs decrease plasma homovanillic acid concentrations in those schizophrenic patients who improve with administration of neuroleptic drugs but not in patients who fail to display a treatment response. Twenty schizophrenic men who remained drug free for at least 2 weeks were treated with 20 mg/d of haloperidol for 5 weeks. Symptoms and plasma homovanillic acid concentrations were assessed on the last drug-free day and weekly for 5 weeks. Mean plasma homovanillic acid concentrations decreased in the group of patients who responded to neuroleptic treatment and did not change in the group of patients who did not improve. These findings suggest that there may be a qualitative distinction between responders and nonresponders to dopamine antagonists.

Administration, Oral↗
PubMed1991

Effects of indomethacin on plasma homovanillic acid concentration in normal subjects: a study of prostaglandin-dopamine interactions.

In laboratory animals, prostaglandins have been shown to act as endogenous neuromodulators of central dopamine (DA) activity. To examine the interaction between prostaglandins and DA in man, the effect of a prostaglandin synthesis inhibitor, indomethacin, was studied on plasma concentrations of the DA metabolite, homovanillic acid (pHVA). Indomethacin (150 mg PO) as compared to placebo significantly elevated mean pHVA concentrations in eight normal subjects. Results of this study support the hypothesis that, as in animals, inhibition of prostaglandin synthesis increases central DA turnover in man.

Adult↗
PubMed1991

Nongenital pelvic leiomyosarcoma metastatic to the heart.

A patient who had a 5-year history of a low-grade nongenital pelvic leiomyosarcoma was evaluated for worsening dyspnea, hypertension, and jugular venous distension. An echocardiogram revealed a large right atrial mass. At surgical exploration, metastatic leiomyosarcoma was found within the inferior vena cava extending from below the renal veins up into the right atrium. Using cardiopulmonary bypass with profound hypothermia and circulatory arrest, the inferior vena cava was opened below the renal veins, and the tumor was transected. That portion of the tumor above this transection was then extracted through a right atriotomy. Resection of the pelvic tumor was not thought to be feasible. The patient remains asymptomatic with stable pelvic tumor 1 year after the procedure.

Female↗
PubMed1991

Factors affecting response of groups of dairy cows managed for different calving-conception intervals.

Factors which positively or adversely affect the response of cow groups to different planned conception periods were analyzed and quantified. Cows were randomly assigned to groups for breeding at postpartum intervals of 35 to 59, 60 to 90 and 120 to 150 days in a research herd, or 60 to 90 and 120 to 150 days in a cooperating commercial herd, with a planned preceding dry period of 60 days in both herds. Breeding at 35 to 59 and 60 to 90 days post partum resulted in a lower conception rate among multiparous cows but had no effect on primiparous cows. Genital disorders such as metritis, retained placenta, vulva inflammation and vaginitis, did not affect the start of luteal activity or length of the subsequent cycles, but caused a significant delay of the first behavioral estrus and, consequently, a delay of the first insemination in the earlier breeding groups. About 30% of the cows in the different categories were inseminated three or more times and were considered to be repeat breeders. Response rates (number of cows conceiving on time/number assigned) in the later breeding group improved due to higher submission rates (number of cows submitted on time/number assigned), and the conception rates were higher (number of cows conceiving on time/number submitted). The rates in all groups were adversely affected by repeat breeding and genital disorders. The latter delayed the first insemination and the conception rate.

Journal Article↗
PubMed1991

Brief neuroleptic discontinuation and clinical symptoms in Kraepelinian and non-Kraepelinian chronic schizophrenic patients.

Neuroleptic medication was abruptly discontinued in 24 male chronic schizophrenic patients who were subdivided on the basis of their history of illness into Kraepelinian (n = 8) and non-Kraepelinian (n = 16) subgroups. These patients were kept drug free for 6 weeks and then returned to treatment with haloperidol, 20 mg/day. Half of the non-Kraepelinian patients developed exacerbations of their symptoms, which quickly resolved when they were returned to medication, while none of the Kraepelinian patients showed a worsening of symptomatology. On-medication clinical severity failed to predict risk for exacerbation, with severity of exacerbation predicting the amount of improvement when returned to medication. The Kraepelinian patients were found to be much less variable than the non-Kraepelinian patients in their symptoms during both medication manipulations, suggesting that medication truly has a negligible effect on them.

Antipsychotic Agents↗