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R Dyer

Publications and source records attributed to R Dyer.

53 records · Page 3Linked to original sources
PubMed1983

Elevation of circulating prolactin concentrations may not cause striatal dopamine receptor supersensitivity.

Neuroleptic drugs, on repeated administration, increase plasma prolactin levels and induce behavioural and biochemical changes suggesting supersensitivity of striatal dopamine receptors. It has been suggested that the increase in plasma prolactin is responsible for the change in striatal dopamine receptors. We now find that repeated administration of haloperidol (5 mg/kg i.p.) for 21 days, followed by a 3 day drug-washout period, caused a 12-fold increase in circulating prolactin concentration in samples taken 1 h after the last injection. Haloperidol treated animals also exhibited an exaggerated stereotyped response to apomorphine 0.0625-0.5 mg/kg s.c.) and an increase in striatal dopamine receptor numbers labelled by [3H]spiperone. Administration of the same dose of domperidone or sulpiride (5 mg/kg i.p., 21 days), compounds which penetrate poorly into brain, also elevated plasma prolactin levels, but failed to alter cerebral dopamine function. Our findings indicate that neuroleptic-induced elevations in plasma prolactin levels are not responsible for the induction of cerebral dopaminergic supersensitivity.

Animals↗
PubMed1983

Giant-cell reparative granuloma of the hands and feet.

Giant-cell reparative granuloma occurring outside the jaw is unusual, being seen predominantly in the tubular bones of the hands and feet. It produces a lucent, expansile lesion in the metacarpals, metatarsals, or phalanges. The authors describe the radiographic and pathological features of 5 cases and review the literature.

Adolescent↗
PubMed1981

Hypophysectomy does not prevent development of striatal dopamine receptor supersensitivity induced by repeated neuroleptic treatment.

Hruska et al. (1980) reported that hypophysectomy prevented the onset of dopamine receptor supersensitivity. We have repeated this investigation administering haloperidol (0.75 mg/day) or sulpiride (2 X 15 mg/day) or saline for 17 days, followed by a 3 day drug washout period, to sham-operated or hypophysectomised rats. Haloperidol or sulpiride pretreatment caused an enhancement of apomorphine-induced stereotyped behaviour and increased the number of specific striatal [3H]spiperone binding sites (Bmax) in both hypophysectomised and sham-operated animals compared to their respective saline controls. We conclude that hypophysectomy does not prevent the onset of striatal dopamine receptor supersensitivity induced by repeated neuroleptic treatment in the rat.

Animals↗
PubMed1980

Percutaneous transluminal dilatation of the renal arteries: techniques and results.

The techniques and results of percutaneous transluminal angioplasty (TPA) of the renal arteries were evaluated in 20 hypertensive patients with 25 renal artery stenoses. Follow-up angiograms have been obtained in nine patients. Many patients had evidence of both essential and angiotensinogenic hypertension. Eleven patients had evidence of severe diffuse atherosclerotic disease, and nine patients had evidence of renal insufficiency. The mean systolic pressures before and after PTA were 203.80 and 150.30, respectively. The mean diastolic pressures before and after PTA were 117.45 and 85.95, respectively. Ten patients were cured. Six patients with long histories of hypertension and a recent increase in blood pressure were classified as having blood pressure easier to control with antihypertensive medication following PTA. Three patients failed to respond to PTA, and one patient was a technical failure. The advantages of this technique include avoidance of general anesthesia and a major surgical procedure, decreased cost, and a shortened hospital stay. The technique can be easily repeated if necessary, and future surgical intervention is not precluded if the method is unsuccessful.

Adult↗
PubMed1975

An electron microscopic study of the effects of portacaval shunts on the ultrastructure of the rat liver after partial hepatectomy.

The normally quiescent stable adult liver has a generous capacity for reparative hypertrophy and hyperplasia after loss of functional tissue. The large reserve of the liver's functional capacity permits survival of the animal even if over 70 per cent of its liver is removed. It retains an inherent capacity for regenerative growth which subsides once the original organ deficit is restored. This study attempted to resolve the question of whether alteration in hepatic hemodynamics affects the regenerative stimulus of the liver after partial (70 per cent) hepatectomy. It has shown that the liver remnant regenerates after reduction of portal blood flow by construction of a portacaval anastomosis. The diversion of blood from the liver exerts its own histologic and electron microscopic effects on the liver. Reduction of portal blood flow affects the temporal patterns of regeneration after partial hepatectomy but does not prevent completion of the regenerative process. Correlation of this study with the biochemical data available in the literature indicates that the structural changes in the cellular organelles during the process of regeneration reflect dynamic biochemical events that are based on a predetermined genetic code representing the key to life that is uniquely found in the liver.

Animals↗
PubMedDate not supplied

A single and multiple dose pharmacokinetic and metabolism study of meclofenamate sodium.

A single and multiple oral dose administration study of meclofenamate sodium (Meclomen) was conducted in ten healthy male volunteers. An initial 300 mg oral dose on day 1 was followed by a 100 mg every 8 h dosage regimen on study days 4 through 18. Intensive plasma and urine sample collection was carried out over the first three study days, and for 120 h following administration of the final dose on day 18. Plasma and urine specimens were analyzed by a specific HPLC assay for unconjugated meclofenamic acid and metabolites I and II of meclofenamic acid before and after sample incubation with beta-glucuronidase. Meclofenamic acid was rapidly absorbed following oral dose administration. Concentrations of meclofenamic acid existed primarily as unconjugated drug in plasma, with only a small amount present in the conjugated form. Meclofenamic acid was rapidly eliminated, with an elimination half-life of approximately 1.3 h. This resulted in no detectable accumulation upon multiple dose administration. Metabolite I, which is one-fifth as active as meclofenamic acid in in vitro inhibition of cyclooxygenase, was present in unconjugated form at steady state in concentrations approximately 50 per cent of those of meclofenamic acid, as unconjugated drug. The majority of metabolite I in plasma existed as glucuronide conjugate. Metabolite II, which is inactive, was present in very significant concentrations in unconjugated form. Plasma protein binding determinations conducted on meclofenamic acid and metabolite I indicated that the free fraction of metabolite I was 8.7 to 10.9 times higher than that of meclofenamic acid. When the lower activity and lower steady state concentrations, but higher free fraction, are considered, it would appear that metabolite I may contribute significantly to the in vivo inhibition of cyclooxygenase activity seen after administration of meclofenamic acid.

Adult↗
PubMedDate not supplied

Sorption of radioactive contaminants by sediment from the Kara Sea.

The purpose of this study is to quantify some of the parameters needed to perform near-field modelling of sites in the Kara Sea that were impacted by the disposal of radioactive waste. The parameters of interest are: the distribution coefficients (Kd) for several important radionuclides, the mineralogy of the sediment, and the relationship of Kd to liquid-to-solid ratio. Sediment from the Kara Sea (location: 73 degrees 00'N, 58 degrees 00'E) was sampled from a depth of 287 m on August 23/24, 1992. Analysis of the material included mineralogy, grain size and total organic carbon (TOC). Uptake kinetics were determined for 85Sr, 137Cs, 241Am, 99Tc, 1251, 232U and 210Pb and distribution coefficients (Kd) were determined for these radionuclides using batch type experiments. Sorption isotherms, developed for 137Cs, 85Sr and 99Tc, were linear in each case. Increasing the liquid-to-solid ratio strongly increased uptake of 137Cs and moderately increased uptake of 99Tc. Analysis for anthropogenic radionuclides indicated the presence only of 239/240Pu in the sediment with the highest activity (at the top section of the core) being 0.420 Bq kg(-1). Other anthropogenic radionuclides were below detection limits.

Absorption↗
PubMedDate not supplied

[Complicated acute appendicitis as intercurrent disease in patient with advanced gastric cancer].

We report a case of a male 64 years old with acute abdomen who was operated with the presumptive diagnosis of complicated acute appendicitis. However the patient had black stools for two months, associated with epigastric pain. Endoscopic diagnosis was: Advanced Gastric Cancer: Borrmann II. Histology was informed as: Infiltrating adenocarcinoma intestinal type middlingly differentiated. Surgery findings were: peritonitis with perforated appendicitis in its base: Free coprolites and carcinomatosis. Histology was reported as: ulcerated mucous in caecal appendix, necrosis and perforation of the muscular wall in the base. Mesentery samples were informed with fat tissue involvement by infiltration of tubular adenocarcinoma.middlingly differentiated, suitable with primary gastric cancer.

Abdomen, Acute↗