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Biomedical subjects

T Ahmad

Publications and source records attributed to T Ahmad.

At least 73 records · Page 4Linked to original sources

Differentials in health-related variables among children at a diarrhoea training unit in Pakistan.

The study assesses gender differences and other variables related to diarrhoea in 500 children less than two years of age at a diarrhoea training unit (DTU). During the study period, 78% of the children (51% males and 49% females) who were brought for care had no dehydration. More female children were malnourished than male. Exclusively bottle-fed infants were malnourished in higher proportion than those breastfed exclusively or partially. With worsening of nutritional status, severity of dehydration increased but it had no effect on the frequency of dysentery which was seen in 11 females and 10 males. Appropriate supplementary feeding was alarmingly low. Eighty-seven per cent of children 9-24 months of age had received their immunisation against measles. All children were rehydrated at the DTU and not a single case required admission. The study does not show preferential care-seeking for male children and suggests that educational efforts be focused on exclusive breastfeeding, appropriate weaning and home management of those cases with no dehydration.

Breast Feeding↗

Effect of dehydration on the disposition kinetics of erythromycin in rabbits.

The effect of water deprivation on the physiologic, biochemical, and disposition parameters of erythromycin was investigated in rabbits. The packed cell volume, plasma glucose, and total lipid concentration increased significantly in dehydration. The pharmacokinetic parameters of erythromycin after intravenous administration also changed, suggesting a need for monitoring toxicity of erythromycin in the water-deprived population.

Animals↗

Physical symptoms and illness attributions in agoraphobia and panic.

The cognitive model of panic disorder proposes that panic patients interpret physical symptoms in a catastrophic way, thus precipitating panic attacks. This study describes the development of a questionnaire measure designed to assess beliefs about the health implications of various symptoms. Two groups, agoraphobics and normals, were compared on a variety of measures. Agoraphobics showed much higher panic frequency, fear of anxiety, and prevalence of frightening cognitions when anxious, but did not score higher than normals when assessing seriousness of symptoms. The implications of these results are considered.

Adult↗

Effect of viscosity and buffer salts on the stability of sulphacetamide solutions.

A study of identification and rate determination of degradation products of sulphacetamide in aqueous solutions during UV irradiation and thermolysis at 70 degrees , 80 degrees and 90 degrees C is made. The effect of viscosity and buffer salts in presence of antioxidants on the rate of hydrolysis is investigated. An increase in the viscosity of solution results in a decrease in the rate of hydrolysis. Similar viscosity effect has been observed on the photolysis of sulphacetamide solutions. No significant salt effect on the rate of hydrolysis of sulphacetamide in citrate and phosphate buffers (pH7.4) has been noticed. The thermodynamic parameter, E(a), deltaH, deltaS for the reaction have been determined.

Journal Article↗

Diagnosis of urinary tract infection in children: fresh urine microscopy or culture?

Fresh unspun and unstained urine specimens from 342 children with previous urinary tract infection (UTI) or symptoms compatible with a UTI were examined by microscopy at a magnification of x 400 in a mirrored counting chamber by a clinician, and sent for culture in a microbiology laboratory; 200 samples were also plated onto dip-slides. When microscopy and culture results were discrepant, further urine samples were collected until a diagnosis of UTI (24) or sterile urine (318) could be confirmed. Initial microscopy correctly identified 23 of 24 UTIs and 286 of 318 sterile urines; 1 false-positive result was caused by vaginal contamination with lactobacilli. 32 specimens (9%) gave an equivocal result on microscopy; the 1 other true-positive result was identified correctly on microscopy of the next urine specimen obtained. Culture of the initial urines correctly identified all 24 UTIs, but only 82% of the negative samples. Of the samples from uninfected children, 35 (11%) showed a mixed growth which was sterile on repeat sampling, and 21 (6.6%) initially grew a false-positive pure growth of more than 10(5) colony-forming units/ml of one organism. True UTIs were associated with bacterial counts above 10(7)/ml. Microscopy by a clinician represents a cheaper, quicker, and more reliable screening test for UTI in children than does routine culture in a microbiology laboratory.

Adolescent↗

Urine collection from disposable nappies.

Urine was collected for microscopy and culture by standard use of sterile adhesive bags and by extraction from wet disposable nappies from 45 patients aged 1 to 23 months. Urine can readily be obtained by compression of wet nappy fibres within a 20 ml syringe if highly absorbent brands that contain gel beads are avoided. Red and white cell numbers were reduced on light microscopy of specimens obtained from nappies, but bacterial counts were unchanged. On culture, 6 children were shown to have urinary tract infections by both methods; of the children who did not have a urine infection, the contamination rate was lower from nappy collections (10/39 vs 17/39 from urine bags). Biochemical analysis of urine collected from 11 older children showed very close correlation for sodium, potassium, urea, and creatinine concentrations and osmolality between freshly voided urine and samples obtained after they were soaked into disposable nappies for 3 h and reclaimed, although there was greater variation for measurements of calcium and phosphate. Extraction of urine from disposable nappies put on within 4 h and which are not soiled by faeces is an inexpensive, rapid, and simple method to collect urine from young children for culture, microscopy for bacteria, and biochemical analysis.

Colony-Forming Units Assay↗

A study on stability of mestranol.

Mestranol, a synthetic oestrogcn, is an oral contraceptive given alongwith progestogens. It is light, heat and air sensitive and on uv irradiation new polymeric species of glucosiduronate and sulphate conjugate are formed. The new species fractions of mestranol are separatable over sephadex in column chromatography and characterized by analytical techniques employed in this investigation. This investigation is aimed to study formation of these species quantitatively for stability induced formulations.

Journal Article↗

The conversion of primaquine into primaquine-aldehyde, primaquine-alcohol, and carboxyprimaquine, a major plasma metabolite.

Although efficacy and toxicity of primaquine (PQ) depend on bioconversion, the process is poorly understood, even for carboxyprimaquine (CPQ), the major plasma metabolite. Earlier work to clarify drug metabolism showed that PQ could be converted quantitatively into CPQ, in vitro, with human erythroleukemic K562 cells or nonleukemic bone marrow supplemented with calf serum. We have now found--using systems with serum only, as well as with K562, bone marrow, and adult or embryonic liver cells--that the bioconversion of the side chain of PQ involves a branched pathway with at least three separate enzymes and two derivatives other than CPQ. An oxidase activity in serum converted PQ first into a novel side chain aldehyde (Y). Aldehyde dehydrogenase transformed PQ-aldehyde into CPQ in cell-free systems and in K562, bone marrow, and adult liver cells. Embryonic hepatocytes or bone marrow treated with 1,3-bis(2-chloroethyl)-1-nitrosourea did not produce CPQ; instead, they made a metabolite (Xc) that we could synthetize via PQ-aldehyde and identify as PQ-alcohol. PQ-alcohol replaced CPQ as the final product whenever alcohol-dehydrogenase prevailed over aldehyde dehydrogenase. These enzymes operated in intact cells and controlled the biotransformation of PQ absolutely. Unless both dehydrogenase were absent, inhibited, or deprived of coenzyme, potentially cytotoxic PQ-aldehyde intermediate did not accumulate. Some of the unique tissues schizonticidal and gametocidal effects of PQ may depend on the distribution pattern and relative activities of PQ oxidase, aldehyde dehydrogenase, and alcohol dehydrogenase in human subjects and in parasites.

Alcohols↗

Pyogenic meningitis in hospitalized children in Kelantan, Malaysia.

A 2.5-year retrospective study of pyogenic meningitis in hospitalized children in Kelantan was carried out with regard to aetiology, clinical features, investigation, treatment and outcome. There were 58 children with 43 cases (74.1%) occurring below the age of 1 year. Frequent presenting symptoms included fever (98.3%), fits (77.6%), anorexia (39.7%), vomiting (34.5%) and drowsiness (12.1%). On admission, 37 (63.7%) had neck stiffness, 10 (17.2%) had Kernig's sign and 32 (55.2%) had coma. CSF cultures were positive for Haemophilus influenzae in 29 (50%), Streptococcus pneumonia in 13 (22.4%) and Neisseria meningitidis in 3 (5.2%). The antibiotic sensitivity profiles showed that the three main organisms were 100% sensitive to Chloramphenicol, Streptococcus pneumoniae was 100% sensitive to penicillin, Neisseria meningitidis was 100% sensitive to penicillin and ampicillin, and Haemophilus influenzae was 90% sensitive to penicillin and ampicillin. The total hospital mortality was 18.9%. All but two of the eleven deaths occurred in children younger than 1 year. Nineteen of the 35 (54.3%) survivors attended for at least one follow-up after discharge from hospital. Of these 19 children, 47.4% had neurological sequelae.

Anti-Bacterial Agents↗

Multicomponent spectrophotometric assay of sulphacetamide and photodegradation products.

A multicomponent, spectrophotometric method has been developed for the simultaneous determination of sulphacetamide, sulphanilamide and major degradation products in photolysed solutions. It is based on a three component (Sulphacetamide, sulphanilamide and azobenzene-4, 4'-disulphonamide) assay at pH 4.0 using 258, 268 and 320 nm as analytical wavelengths. The blue oxidation product of sulphanilamide is determined independently at 550 nm. The reproducibility of the method judged by the analysis of synthetic mixtures, is within +/- 5%. The method is stability indicating for the assay of sulphacetamide in degraded eye-drop preparations and could also be conveniently used for photodegradation studies.

Journal Article↗

Failure of spermatozoa from T/t mice to fertilize in vitro is overcome by zona drilling.

Failure of epididymal spermatozoa from T/t mutant mice, but not from t/t individuals, to fertilize oocytes in vitro was partially overcome by opening a small aperture in the zona pellucida with acidified Tyrode's solution to permit direct access of the spermatozoon to the vitellus. This study provides a model system to evaluate requirements for successful zona drilling in the treatment of human infertility and further insights into the effects of the t complex on sperm fertility.

Animals↗

Reversible renal failure due to the use of captopril in a renal allograft recipient treated with cyclosporin.

Angiotensin-converting enzyme (ACE) inhibitors are widely used for the treatment of hypertension, but caution is advised because these drugs may induce reversible acute renal failure. Although this has been ascribed in some cases to nephrotoxicity, hypotension, a hypersensitivity reaction, and interstitial nephritis, most cases have been associated with stenosis of the renal arteries or arterioles occurring in either native or transplanted kidneys. We describe a case of reversible acute renal failure due to the use of captopril in a renal allograft recipient who had no evidence of any of these conditions, but who was also receiving cyclosporin therapy.

Acute Kidney Injury↗

Photo-oxidation of sulphanilamide to azo and azoxy compounds.

The second-order kinetics for the photochemical formation of azobenzene-4, 4-disulphonamide has been studied at pH 1-11 and at pH 7.0 in the presence of five antioxidants. The rate constants are not affected by changes in pH in the region of 5-9 at which the molecule is predominantly in the unionised form. The rate of formation of azobenzene-4, 4'-disulphonamide is inhibited upto 80% by ascorbic acid. A scheme for the photo-oxidation of sulphanilamide to the azo and azoxy derivatives has been outlined.

Journal Article↗

Photo-oxidation of sulphanilamide to blue product.

Aqueous solutions of sulphanilamide undergo photolysis to produce several compounds including the blue oxidation product. The kinetics of the reaction leading to blue product has been studied and the apparent first-order rate constants for the formation of blue product at pH 1-11 have been calculated. Effect of certain antioxidants on this reaction at pH 7.0 and rates of inhibition have been determined. Ascorbic acid has been found to completely inhibit the formation of blue product. A reaction pathway for the photo-oxidation of sulphanilamide to blue product has been suggested. The blue product has been shown (James, 1940) to possess much higher antibacterial activity than sulphanilamide.

Journal Article↗

EFFECT OF pH ON THE PHOTOSTABILITY OF SULPHACETAMIDE EYE-DROP SOLUTIONS.

The photolysis of aqueous solutions of sulphacetamide and sulphanilamide has been studied at pH 3-11. The rate of phatolysis appears to be the highest around pH 5.0 and 3.0 for sulphacetamide and sulphanilamide respectively. The log k-pH profiles of both compounds in the buffered and unbuffered solutions are presented. Various buffer ions e.g. citrate and phosphate catalyase the photodegradation reactions. Sulphacetamide eye-drop solutions prepared at pH 7 to 9 have ideal stability and clinical efficacy.

Journal Article↗

Stability-indicating assay of sulphacetamide in thermally degraded solutions.

A stability-indicating assay method for the determination of sulphacetamide in thermally degraded solutions is reported. The method is based on the difference in the absorption maxima of sulphacetamide and sulphanilamide at pH 4.0 and their simultaneous determination by a two component assay using the analytical wavelengths of 258 nm and 268 nm the reproducibility of the method lies within +/- 4%. It is rapid and specific for the assay of sulphacetamide in degraded opthalmic preparations.

Journal Article↗