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Biomedical subjects

B Pollock

Publications and source records attributed to B Pollock.

At least 37 records · Page 2Linked to original sources
PubMed1999

Cerebral glucose metabolic response to combined total sleep deprivation and antidepressant treatment in geriatric depression.

OBJECTIVE: The treatment of geriatric depression is complicated by a variable and delayed response to antidepressant treatment. The present study was undertaken to test the hypothesis that combined total sleep deprivation and paroxetine treatment would produce a persistent reduction in glucose metabolism in the anterior cingulate cortex similar to that reported after long-term antidepressant treatment. METHOD: Six elderly depressed patients who met the DSM-IV criteria for major depressive disorder and six age-matched comparison subjects underwent serial positron emission tomography (PET) studies at baseline, after total sleep deprivation, after recovery sleep (after the initial paroxetine dose), and after 2 weeks of paroxetine treatment (patients only). The PET data were analyzed by using statistical parametric mapping methods. RESULTS: The patients' scores on a 13-item version of the Hamilton Depression Rating Scale were decreased after total sleep deprivation, after recovery sleep, and after 2 weeks of treatment. The Hamilton depression scores of the comparison subjects were not significantly altered. In the patients, the greatest reductions in normalized, relative glucose metabolism after sleep deprivation were observed in the anterior cingulate cortex (Brodmann area 24), and they persisted after recovery sleep and antidepressant treatment. The comparison subjects demonstrated increased metabolism in these areas. CONCLUSIONS: Improvement in the patients' depressive symptoms was accompanied by reduced glucose metabolism in the right anterior cingulate cortex and right medial frontal cortex. These preliminary data indicate that in elderly depressed patients, total sleep deprivation may accelerate the clinical and glucose metabolic response to antidepressant treatment.

Age Factors↗
PubMed1998

Pharmacokinetics and metabolism of [14C]dichloroacetate in male Sprague-Dawley rats. Identification of glycine conjugates, including hippurate, as urinary metabolites of dichloroacetate.

Pathways of metabolism of dichloroacetate (DCA), an investigational drug for the treatment of lactic acidosis in humans and a rodent hepatocarcinogen, are poorly understood. In this study, rats were given, by gavage, one or two 50 mg/kg doses of NaDCA. DCA labeled with 14C (carboxy carbon) or 13C (both carbons) was used in studies of disposition and pharmacokinetics, respectively. The effect of fasting for 14 hr before dosing was studied. Expired air, urine, feces, and tissues were collected from [14C]DCA-dosed rats. Urine was analyzed by HPLC, GC/MS, and NMR spectroscopy. Plasma samples were analyzed by GC/MS. DCA plasma elimination half-lives were 0.1 +/- 0.02 and 5.4 +/- 0.8 hr in young adult rats (180-265 g, 3-4 months of age) given one or two doses of DCA, respectively, and 9.7 +/- 1 hr in large, 16-month-old rats given two DCA doses. The percentage of the DCA dose excreted as CO2 varied from 17 to 46% and was lower (p < 0.001) in fed rats, compared with rats fasted overnight before dosing. Urine contained DCA and DCA metabolites, including oxalate, glyoxylate, and conjugated glycine (mainly hippurate and phenylacetylglycine). More unchanged DCA was excreted by large rats pretreated with DCA (mean, 20.2% of the dose) than by young adult rats given one dose of DCA (mean, 0.5%). This study confirmed that CO2, glycine, and oxalate are major products of DCA metabolism, it demonstrated that one dose of DCA altered the elimination of a subsequent dose, and it showed that age or body size, as well as access to food, significantly affected DCA metabolism in rats.

Animals↗
PubMed1993

Overexpression of Desulfovibrio vulgaris Hildenborough cytochrome c553 in Desulfovibrio desulfuricans G200. Evidence of conformational heterogeneity in the oxidized protein by NMR.

Plasmid pRC41, containing the cyf gene encoding cytochrome c533 from Desulfovibrio vulgaris Hildenborough, was transferred by conjugation from Escherichia coli to Desulfovibrio desulfuricans G200. The structural properties of the purified protein were studied by one-dimensional and two-dimensional NMR. A heterogeneity in the folding of the cytochrome isolated from D. vulgaris Hildenborough and from D. desulfuricans G200 was observed for the oxidized from. Temperature, pH and salt-dependence studies indicated that the heterogeneity does not result from an intermediate in the protein unfolding process, but derives from two conformations which are not in dynamic equilibrium.

Amino Acid Sequence↗
PubMed1993

Essential fatty acid deficiency increases interstitial IA-positive cells in rat kidney and accelerates renal allograft rejection.

Essential fatty acid deficiency has been reported to result in depletion of interstitial macrophages from rat kidneys and to permit transplantation of these kidneys across a fully allogeneic barrier without need for immunosuppression. In view of the potential for application of this phenomenon to xenografts, this study attempted to confirm the observation. Kidneys from rats fed normal or essential fatty-acid-deficient diets were transplanted to DA recipients. The donors' livers and contralateral kidneys were analyzed for their fatty acid profile in liver phospholipids, and the kidneys were examined by immunohistology for interstitial Ia(+) cells. EFAD resulted in an increase in renal interstitial Ia(+) cells detected by MRC-OX6 (anti-RT1Bpublic) from 13.5 +/- 2.9 (control diet fed rats) to 22.8 +/- 3.6 in rats on a stringent EFAD diet. Graft survival of kidneys from these EFAD rats was significantly shorter than that of kidneys from control diet fed rats. In direct contrast to the original report, this study found that EFAD caused a marked increase in renal interstitial Ia(+) cells and a reduction in allograft survival of EFAD donor kidneys.

Animals↗
PubMed1993

Acutely psychotic patients receiving high-dose haloperidol therapy.

Despite the trend towards lower neuroleptic dosing in the treatment of psychosis, there continue to be patients who are administered doses that are higher than recommended. Thirty-six acutely psychotic patients receiving parenteral haloperidol were evaluated by the Brief Psychiatric Rating Scale, the Schedule for Affective Disorders and Schizophrenia-Change Version, and the Nurses' Observation Scale for Inpatient Evaluation, as well as by drug levels in plasma. Patients were compared on the basis of total haloperidol dose in the first 24 hours: regular dose (RD: 10-30 mg) and high dose (HD: 40-80 mg). At baseline, patients in the HD group scored significantly higher on the Brief Psychiatric Rating Scale factor Hostile-Suspiciousness and the Nurses' Observation Scale for Inpatient Evaluation factor Irritability. Assignment to regular-dose and HD groups could not be accounted for on the basis of age, gender, weight, or duration of illness. Moreover, drug levels in plasma indicated that the HD patients did not require higher doses on the basis of differences in haloperidol levels.

Acute Disease↗
PubMed1991

Acute effect of intravenous clomipramine upon sleep-related hormone secretion in depressed outpatients and healthy control subjects.

Tricyclic antidepressants have been used frequently as pharmacological probes in neuroendocrine studies even though they appear to lack neurochemical specificity. Despite this, the hormonal responses to these drugs have been used to provide evidence that depressed patients have alterations in both noradrenergic and serotonergic tone within the central nervous system. Most studies have been conducted in the morning, which is not a time of high physiological neuroendocrine secretory activity. The present study has used the relatively specific serotonergic probe intravenous clomipramine given to depressed patients and healthy subjects immediately before sleep onset, which is a time of increased neuroendocrine activity. Under these conditions, 12.5 mg clomipramine stimulates the secretion of both cortisol and prolactin, but unlike studies conducted in the morning, clomipramine suppresses the secretion of growth hormone in both groups. These data suggest that serotonergic mechanisms are involved in the regulation of the secretion of these three hormones at the time of sleep onset.

Adult↗
PubMed1990

Prevalence of neuroleptic-induced dystonia in mania and schizophrenia.

In a prospective study of 41 acutely psychotic patients, neuroleptic-induced dystonic reactions occurred in 62.5% of the manic patients (10 of 16) and 66.7% of the schizophrenic patients (10 of 15), a nonsignificant difference. These findings contradict a recent report suggesting a higher risk for this side effect in mania.

Acute Disease↗
PubMed1988

A study of HPV 1, 2 and 4 antibody prevalence in patients presenting for treatment with cutaneous warts to general practitioners in N. Ireland.

Three hundred and seventy-six patients attending their general practitioner with cutaneous warts at five health centres in Northern Ireland were screened for human papilloma virus (HPV) types 1 and 2 IgM antibody using an indirect immunofluorescence test. Eight-eight (23.4%) patients were positive for HPV type 1 IgM and 156 (41.5%) for HPV type 2 IgM. HPV 1 IgM antibody was significantly more likely to be associated with plantar warts than warts elsewhere (P less than 0.0001). HPV 2 IgM was present in 45 (34.1%) patients with plantar warts and 99 (45.6%) patients with warts at other sites (P = 0.1). Evidence of multiple infection by HPV types 1 and 2 was demonstrated by the finding of HPV 1 and 2 IgM antibodies in the sera of 16 (4.3%). HPV 4 was found in only 1 out of 30 biopsies and HPV 4 IgM was undetectable in 50 randomly chosen sera.

Antibodies, Viral↗
PubMed1988

Combined vaccine against measles, mumps, rubella, and varicella.

A combined measles, mumps, rubella, and varicella vaccine produced seroconversions for all four components similar to that found if measles, mumps, and rubella vaccine or live varicella vaccine were given separately. In addition, those exposed to varicella were completely protected or had only a mild rash. Moreover, the reaction rates were not increased if the vaccines were combined. The somewhat lower and delayed serologic response to live varicella vaccine as compared with the combined measles, mumps, rubella, and varicella may have been due to the small amount of varicella vaccine virus used or to its degree of attenuation. Persistence of antibody was observed 1 year postimmunization.

Antibodies, Viral↗
PubMed1988

[Preventive antifibrillatory treatment of sudden cardiac death in acute myocardial infarct].

The pathophysiological basis of sudden cardiac death due to ventricular arrhythmias in acute myocardial infarction has been extensively investigated in experimental as well as in some clinical studies. Numerous clinical studies have been performed with the aim to establish the feasibility of antifibrillatory prophylaxis of sudden cardiac death by pretreatment with antiarrhythmic drugs. Using class I-antiarrhythmic drugs the reported findings were contradictory. While the antiarrhythmic efficacy of Lidocaine and other, newer class I-antiarrhythmic drugs is well established, the antifibrillatory effects of these drugs in the early phase of acute myocardial infarction remain uncertain. In clinical studies with the endpoint of mortality in patients at risk, longterm administration of orally effective class I-antiarrhythmic drugs did not prove to be superior to placebo. However, beta-sympatholytic agents have been shown to reduce mortality in patients at risk in several large clinical studies. The basic mechanism seems to be primarily a reduction in sudden cardiac death which is caused predominantly by ventricular fibrillation. The antifibrillatory properties of beta-blockers was demonstrated as well by a reduction in the number of episodes of ventricular fibrillation. The recognition of patients at risk who profit most from chronic beta-blocker therapy remains the main problem when treatment of numerous low-risk patients is avoided. In the ISIS I-study with Atenolol intravenous administration of a beta-blocker in the early phase of acute myocardial infarction has been shown to be beneficial if hemodynamic monitoring, for example using flow-directed heart catherization is performed. In general this does not apply to the treatment with calciumantagonists, especially with Verapamil and Nifedipine. These drugs do not improve prognosis of acute myocardial ischemia, obviously because of hemodynamic side effects. The antifibrillatory efficacy of Verapamil-type calciumantagonists, shown in the experimental model, could not be demonstrated in the clinical setting. Nevertheless, further clinical studies performing longterm prophylactic treatment of patients at risk before the onset of myocardial ischemia seem to be worthwhile. Concerning class III-antiarrhythmic agents, clinical experience in the setting of acute myocardial infarction is limited; hence a final conclusion about their antifibrillatory efficacy under clinical conditions at present is impossible.

Anti-Arrhythmia Agents↗