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Biomedical subjects

R A Ahmad

Publications and source records attributed to R A Ahmad.

At least 19 recordsLinked to original sources
PubMed1994

Effects of estradiol on worm burden and peripheral leukocytes in Parastrongylus malaysiensis-infected rats.

Gonadectomized male laboratory rats were given 0.06 mg/kg estradiol benzoate daily for 14 days before being inoculated with 50 third-stage larvae of Parastrongylus malaysiensis. Hormone treatment was continued until the rats were killed. The numbers of larvae in the brain and of adult worms in the pulmonary area of the rats were determined every 7 days after the inoculation. It was found that the rats treated daily with estradiol benzoate had significantly and consistently higher numbers of larvae and adult worms as compared with the controls. The number of total leukocytes increased significantly after the rats were infected. The results show that estradiol-treated rats become susceptible to P. malaysiensis infection, which may indicate that the immunosuppressive effects of testosterone observed in earlier studies may partly be caused by estradiol that was peripherally aromatized from testosterone.

Angiostrongylus↗
PubMed1994

The influence of thyroxine and propyl thiouracil on Parastrongylus malaysiensis infection in rats.

Daily intramuscular injection with thyroxine (T4) at a dose of 2.5 micrograms/100 g body weight decreased the larvae and adult worm burden of Parastrongylus malaysiensis in the brain and pulmonary arteries of male Sprague-Dawley albino rats. In contrast, rats treated with propyl thiouracil (PTU), an antithyroid drug, at a dose of 3.75 mg/100 g body weight retained greater numbers of larvae and adult worms. The results may reflect the contrasting immunomodulatory effects of T4 and PTU that influence the susceptibility of the host.

Angiostrongylus↗
PubMed1992

Worm burden and leukocyte response in Angiostrongylus malaysiensis-infected rats: the influence of testosterone.

Gonadectomized male albino rats aged 7 weeks were given 1.5 mg/kg testosterone propionate daily and inoculated with 50 third-stage larvae of Angiostrongylus malaysiensis. The treatment significantly increased the number of larvae and adult worms recovered from the brain and pulmonary arteries, respectively, and the rats exhibited smaller thymus glands. The total numbers of leukocytes, monocytes, neutrophils, and especially eosinophils increased significantly post-infection, but the counts were higher in the untreated infected controls. Presumably, immunosuppressive effects of testosterone may at least partly be responsible for the higher loads of A. malaysiensis worms found in male rats as compared with females in the field.

Angiostrongylus↗
PubMed1992

Pleural effusion following coronary perforation during balloon angioplasty: an unusual presentation of the postpericardiotomy syndrome.

We report on the development of features of the postpericardiotomy syndrome following coronary perforation during balloon angioplasty, in a patient that was managed conservatively. The case illustrates that while cardiac tamponade does not invariably follow coronary perforation, late consequences derived from this complication may occur. It also widens the spectrum of conditions where the postpericardiotomy syndrome has been observed.

Angina Pectoris↗
PubMed1992

Patients with suspected myocardial infarction: effect of mode of referral on admission time to a coronary care unit.

The aim of this prospective study was to determine the delay between the onset of symptoms and arrival in the coronary care unit of patients with suspected acute myocardial infarction, and the relative contribution to the total delay of patient delay, method of referral (self referral or general practitioner referral) and delay in the hospital before reaching the coronary care unit. All patients admitted with chest pain to the coronary care unit at Dudley Road Hospital, Birmingham, over the six month period April-September 1989 were included in the study. Ninety five patients were referred by their general practitioner and 107 patients attended the accident and emergency department directly or arrived by ambulance without contacting their general practitioner. The proportion of self referred and general practitioner referred patients with acute myocardial infarction, angina and non-cardiac chest pain were not significantly different. The total delay was significantly longer for patients who had been referred by their general practitioner (median 5.3 hours) than for self referrals (3.2 hours, P less than 0.001), with a significantly higher proportion of self referrals arriving at the coronary care unit within six hours of the onset of symptoms (77% versus 54%, P less than 0.01). Among general practitioner referrals, initial patient delay accounted for a median of 2.5 hours and the general practitioner's response time for a median of 1.1 hours. The delay in hospital was similar for both groups of patients. In inner city areas, self referral may result in considerably less delay than general practitioner referral allowing a greater proportion of patients to receive effective thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Care Units↗
PubMed1990

Treatment of postural hypotension. A review.

Many drugs have been used in treating patients with postural hypotension but for a large number the evidence of benefit is small and the potential for adverse effects, particularly supine hypertension, is great. Full clinical assessment is essential at the outset to define the nature and extent of pathophysiological disturbance of autonomic function. Many patients can be treated adequately by sleeping with the head of the bed elevated, and the use of fludrocortisone. Patients without evidence of central neurological deficit may benefit from additional treatment with drugs which alter beta-adrenoceptor tone. Patients who respond poorly to these measures should be admitted to hospital, and treatment with desmopressin initiated. Symptomatic postprandial hypotension should be identified early since the response to these measures alone is often poor, caffeine administered before eating, with abstinence for the rest of the day, may be very helpful.

Humans↗
PubMed1989

Unruptured aneurysm of the sinus of Valsalva presenting with isolated heart block: echocardiographic diagnosis and successful surgical repair.

A 31 year old man presented with intermittent dizziness and electrocardiographic evidence of a severe conduction disturbance, with asystolic pauses of up to six seconds, and was treated by implantation of a permanent pacemaker. Echocardiography showed an enlarging aneurysm of the right sinus of Valsalva extending into the interventricular septum. This was confirmed by aortography, and successful surgical repair was carried out. The characteristic diastolic expansion of the aneurysm and the demonstration of continuity between the septal extension and the related aortic sinus were useful diagnostic features.

Adult↗
PubMed1987

Site selection by Microphallus pygmaeus Levinsen, 1881 (Trematoda: Microphallidae) in the laboratory mouse.

When Microphallus pygmaeus Levinsen, 1881 was inoculated orally to laboratory mice, most specimens, failed to attach to the intestinal wall and passed out rapidly with the faeces. Those which did settle were distributed more or less evenly throughout the small intestine by 4 h after inoculation. By day 1 after inoculation the worms had developed to oviposition and most were found in the ileum. By 2 days after inoculation all worms were established, and they remained in this region where they grew and continued egg production with very little further mortality until day 6 after inoculation. Thereafter, gravid worms progressively detached and passed rapidly through the caecum, colon, and rectum with the faeces. All parasites had been voided by about day 12 inoculation. In spite of high mortality, distribution in the small intestine is also affected by the site of implantation.

Animals↗
PubMed1986

Retention and egg production of Microphallus pygmaeus in mice: the influence of the adrenal cortex.

Fewer adult Microphallus pygmaeus are recovered from the small intestine of adrenalectomized male mice than from sham-operated counterparts. Preinfection intraperitoneal injection of 2 IU or 4 IU ACTH daily for 7 days increases the initial primary worm burden in male mice. Preinfection intramuscular injection of 325 micrograms corticosterone daily for 7 days increases the initial worm burden and alters the subsequent rate of decline and duration of the primary infection. However, egg production is unaffected. The changes in parasite numbers are attributed to the immunosuppressive action of corticosterone.

Adrenal Cortex↗
PubMed1983

Pharmacokinetics of melphalan in children following high-dose intravenous injection.

The pharmacokinetics of high-dose IV melphalan (140 or 220 mg m-2) were studied after 12 administrations in 10 children (aged 2.5-16 years) undergoing chemotherapy for either neuroblastoma or Ewing's tumour. To assess whether a simpler and less expensive nitrobenzylpyridine (NBP) spectrophotometric assay for alkylating activity was a satisfactory alternative to high-pressure liquid chromatography (HPLC), the plasma melphalan concentration was estimated by both methods in five cases. Analysis of the disposition of melphalan gave a mean half-life of 1.3 +/- 1.0 (SD) h, clearance 18.4 +/- 9.4 l X h-1 X m-2, and apparent volume of distribution 26.3 +/- 18.0 l X m-2. These pharmacokinetic parameters were similar to those found in adults: no correlation was found between any parameter and age or glomerular filtration rate. NBP alkylating activity determinations yielded consistent results and good correlation with plasma melphalan concentration. However, concordance analysis indicated a consistent bias, the NBP assay always giving lower estimates of plasma melphalan concentration: HPLC assay therefore remains the method of choice for determining plasma melphalan pharmacokinetics.

Adolescent↗
PubMed1983

Pharmacokinetic observations on dapsone in dermatitis herpetiformis.

The pharmacokinetics of dapsone (DDS) and monoacetyldapsone (MADDS) following an oral dose of 150 mg DDS were studied in sixteen patients with dermatitis herpetiformis and seven normal subjects. No differences in DDS disposition were observed between the two groups. The maintenance dose of DDS for individual patients was not significantly correlated with jejunal biopsy morphology, DDS or MADDS half-lives, or the area under the plasma concentration-time curves for DDS or MADDS. DDS plasma protein binding was normal in patients and did not apparently determine the concentration of DDS in skin biopsies, for which the skin/plasma DDS concentration ratio was approximately unity. There was no undue representation of acetylator phenotype in the patient group and no correlation between maintenance dose and MADDS/DDS ratio was noted. The determinants of the maintenance DDS dose have not been found. This may relate to pharmacodynamic differences, but alternatively the concentration of oxidative metabolites rather than DDS or MADDS could be responsible for the therapeutic activity in dermatitis herpetiformis.

Adult↗
PubMed1982

Role of N-acetyltransferase phenotypes in bladder carcinogenesis: a pharmacogenetic epidemiological approach to bladder cancer.

A large excess of patients with bladder cancer who have previously been exposed to N-substituted aryl compounds as a result of the production of dyestuff intermediates have the slow phenotype of the enzyme N-acetyltransferase. Among bladder-cancer patients in general, those presenting with T3 or T4 disease or carcinoma-in-situ also show an excess of the slower subtypes. Either N-substituted aryl compounds more frequently produce tumours with this invasive potential if linked with slow acetylation or slow acetylators are more susceptible to tumour production when exposed to some N-substituted aryl compounds. It is suggested that acetylator status could be used to identify susceptible individuals in potentially hazardous occupations.

Acetylation↗
PubMed1982

Plasma melphalan and prednisolone concentrations during oral therapy for multiple myeloma.

Nine patients with myeloma were studied over 13 oral administrations of 10 mg melphalan and 5-10 mg prednisolone. Plasma melphalan concentrations were estimated by high-pressure liquid chromatography, prednisolone concentrations by quantitative thin-layer chromatography. The mean plasma half-life of unchanged melphalan was 0.9 +/- 0.5 (SD) h. The 'lag-time' before melphalan was detected in the plasma varied from 1 to 4 h, the mean peak concentration was 96 +/- 21 ng/ml, and the mean area under the plasma concentration by time curve was 160 +/- 78 ng h/ml. This variability was consistent with observations made elsewhere following much higher oral doses of melphalan and illustrates the relatively wide interindividual variability of absorption. Observations made in the same subjects on two separate occasions showed lower variability. The melphalan elimination rate was not significantly affected by moderate impairment of creatinine clearance (to 31 ml/min). Absorption of prednisolone in five of these patients was apparently normal and unaffected by concurrent administration of melphalan.

Adult↗