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Biomedical subjects

J Zak

Publications and source records attributed to J Zak.

At least 37 records · Page 2Linked to original sources
PubMed1993

Helicobacter pylori prevalence in non-ulcer dyspepsia--ethnic and socio-economic differences.

Helicobacter pylori is an important cause of gastritis and a number of therapeutic trials suggest that it may be important in the genesis of duodenal ulcer recurrence. The reported prevalence of gastric colonisation by the organism varies considerably. The aim of this cross-sectional survey was to determine its prevalence in non-ulcer dyspeptics and to determine whether this is influenced by age, race, sex, socio-economic status, educational level and the number of persons sharing accommodation. One hundred and sixty-nine patients underwent endoscopy; biopsy specimens were taken from the antrum and H. pylori status was determined histologically. Gastric colonisation was found in 106 patients (63%). The prevalence showed a marked ethnic difference: 40% in whites and 71% in coloureds (P < 0.001). The ethnic groups were characterised by significant differences in socio-economic status (P < 10(-6)), educational level (P < 10(-6)), number of persons sharing accommodation (P < 10(-6)) and age (P < 0.001). These same differences were found when comparing the H. pylori-positive and negative groups, but were less marked and could be attributed to the marked differences between ethnic groups. We conclude that H. pylori prevalence differs between the ethnic groups studied. This may be because of varying degrees of exposure risk.

Adult↗
PubMed1992

N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline, an irreversible receptor inactivator, as a tool for measurement of alpha 2-adrenoceptor occupancy in vivo.

In rats treatment with N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ) induces a dose-dependent decrease in the number of alpha 2-adrenoceptors. Prior injection of alpha-adrenergic agents such as yohimbine and clonidine protect alpha 2-adrenoceptors against the effects of EEDQ. The ED50 values for yohimbine and clonidine were 10.27 and 5.83 mumol/kg, respectively.

Adrenergic alpha-Antagonists↗
PubMed1992

Triple therapy with sucralfate is as effective as triple therapy containing bismuth in eradicating Helicobacter pylori and reducing duodenal ulcer relapse rates.

Duodenal ulcer relapse rates after therapy with sucralfate or bismuth are lower than those after H2-receptor antagonist therapy. This may be mediated by an antibacterial effect of these drugs on Helicobacter pylori. Bismuth has become an integral part of 'triple therapy' because of its documented anti-H. pylori effect. In vitro and clinical data suggest that sucralfate may also have an anti-H. pylori effect. The aim of this randomized, prospective therapeutic trial was to compare the efficacy of triple therapy containing bismuth with that containing sucralfate and to determine the effect of therapy with these combinations on duodenal ulcer relapse. Forty H. pylori-positive duodenal ulcer patients were healed with omeprazole and randomized to receive either 1 g sucralfate four times daily or 120 mg bismuth compound four times daily. All patients received 400 mg metronidazole three times daily and either 250 or 500 mg tetracycline four times daily for 7-14 days. Thirty-five patients could be analysed. Overall eradication rates did not differ in the treatment groups (10 of 17 eradicated with sucralfate and 11 of 18 with bismuth). Relapse rates were significantly lower in the eradicated group (1 of 21 compared with 8 of 14 in the non-eradicated group) and did not differ between treatment groups in those patients not eradicated. A triple therapy regimen utilizing sucralfate appears to be as effective as the bismuth-containing regimen.

Bismuth↗
PubMed1991

Acid secretory responses and parietal cell sensitivity following duodenal ulcer healing with omeprazole, sucralfate, and Maalox.

Acid secretory responses and parietal cell sensitivity (PCS) have been studied in 21 duodenal ulcer patients before and after successful treatment with omeprazole (n = 7), sucralfate (n = 7), or Maalox (n = 7). The second study was carried out 3 days after documented healing and withdrawal of treatment in the sucralfate- and Maalox-treated groups and 14 days after documented healing and withdrawal of treatment in the omeprazole-treated patients. Acid output (mmol/hour) was measured as basal secretion, and in response to 0.1 microgram/kg/hour pentagastrin (low-dose) and 6.0 micrograms/kg/hour pentagastrin (high-dose) stimulation. PCS was calculated as the ratio of low dose:high dose acid output (expressed as a percentage). Ulcer healing with sucralfate resulted in significant (p less than 0.05) decreases in low-dose acid output from 36.4% (13.2-51.0) (median [range]) to 8.4% (3.2-45.4) mmol/hour and PCS from 69.1% (44.9-91.4) to 22.0% (16.0-85.6), whereas no significant decreases in any of the measured parameters were noted following ulcer healing with Maalox. Ulcer healing with omeprazole resulted in significant (p less than 0.05) decreases in basal acid output from 6.3 (1.5-22.9) (median [range]) to 2.2 (0-6.9) mmol/hour, and low-dose acid output from 31.0 (6.0-58.0) to 23.0 (1.4-44.8) mmol/hour. These findings suggest that acid secretory responses following ulcer healing vary according to the therapeutic agent used.

Adult↗
PubMed1991

Lymphocytic gastritis in nonulcer dyspepsia.

The prevalence of lymphocytic gastritis, a specific form of chronic gastritis characterized by infiltration of gastric superficial epithelium with T lymphocytes, has been established in nonulcer dyspepsia. Among a population sample of 586 patients at risk for gastric carcinoma, 0.83% of patients with nonulcer dyspepsia and 1.63% of patients with chronic active gastritis showed lymphocytic gastritis. Among routine gastric biopsies from 5130 patients, only five cases met histological and immunohistochemical criteria of lymphocytic gastritis.

Biopsy↗
PubMed1991

Role of dopaminergic neurons in denervation-induced alpha 1-adrenergic up-regulation in the rat cerebral cortex.

The density of [3H]prazosin binding to alpha 1-adrenoceptors in the rat cortex was measured after selective and mixed noradrenergic or dopaminergic lesions. DSP-4 produced a selective noradrenergic lesion and increased the density of alpha 1-adrenoceptors. 6-Hydroxydopamine produced a selective dopaminergic lesion (after desipramine protection of noradrenergic neurons) and a mixed noradrenergic and dopaminergic lesion that did not change the cortical alpha 1-adrenoceptor binding. On the basis of the results obtained, a hypothesis is put forward that the central dopaminergic system controls the denervation-induced cortical alpha 1-adrenoceptor up-regulation.

Animals↗
PubMed1991

The turnover of rat cortical alpha 1-adrenoceptors is not modified by repeated electroconvulsive treatment.

The effect of repeated treatment with electroconvulsive shock (ECS) on the turnover of cortical alpha 1-adrenoceptors in rats was measured using the N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ)-induced irreversible receptor inactivation method. Repeated treatment with ECS did not affect parameters (the synthesis rate constant r, the degradation rate constant k) of alpha 1-adrenoceptor turnover. Because increase in the density of alpha 1-adrenoceptors in the ECS-treated group disappears later during measurement of turnover, several calculation possibilities were discussed. The present data confirm that repeated treatment with ECS produces a short-lasting up-regulation of cortical alpha 1-adrenoceptors, but does not affect the turnover of this receptor type.

Adrenergic alpha-Antagonists↗
PubMed1991

Effect of repeated treatment with antidepressant drugs and electroconvulsive shock (ECS) on the D2 dopaminergic receptor turnover in the rat brain.

The effect of repeated treatment with citalopram, (+)oxaprotiline, (-)oxaprotiline, imipramine and ECS on the turnover of dopamine D2 receptors in the rat brain was measured using an N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline (EEDQ)-induced irreversible receptor inactivation method. Repeated treatment with citalopram and ECS, but not with (+) and (-) enantiomers of oxaprotiline and imipramine, significantly decreased the turnover of D2 receptors in the striatum. Neither of the applied repeated treatments changed the turnover of D2 receptors in the limbic system. The results suggest that changes in the turnover of D2 dopamine receptors in striatum may participate in the mechanism of antidepressant action of ECS and citalopram, but not that of (+) or (-)oxaprotiline or imipramine.

Animals↗
PubMed1990

The effect of repeated treatment with brofaromine, moclobemide and deprenyl on alpha 1-adrenergic and dopaminergic receptors in the rat brain.

The binding of [3H]prazosin to alpha 1-adrenoreceptors, as well as of [3H]SCH 23390 (R(+)-8-chloro-2,3,4,5-tetrahydro-3-methyl-5-phenyl-1H-3-benzazepine-7-o l) to dopamine D1 receptors, and [3H]spiperone to D2 receptors was studied following repeated administration of the monoamine oxidase inhibitors (MAOI) brofaromine, moclobemide and deprenyl to rats. Scatchard analysis showed no change in the density (Bmax) and affinity (Kd) of [3H]prazosin sites, yet the ability of phenylephrine (an alpha 1-adrenoceptor agonist) to compete for [3H]antagonist binding sites was enhanced in the cerebral cortex after repeated brofaromine administration, as well as in the hippocampus of rats pretreated with moclobemide and deprenyl. The density and the binding affinity of dopaminergic D1 and D2 receptors were not affected by repeated treatment with all the MAOI used. The results seem to indicate that a small increase in the alpha 1-adrenoceptor agonist affinity occurs after repeated administration of MAOI.

Animals↗