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Biomedical subjects

S Othman

Publications and source records attributed to S Othman.

At least 37 records · Page 2Linked to original sources
PubMed1992

Iodine metabolism in postpartum thyroiditis.

To investigate the etiologic role of iodine intake in postpartum thyroiditis (PPT), we have measured postpartum urinary iodine excretion serially in a large prospective study of PPT. A total of 1996 women were screened for thyroid microsomal antibody during the second trimester of pregnancy. One hundred fifty-two of the 235 antibody-positive women and an equal number of age-matched antibody-negative controls were followed postpartum with measurements of urinary iodine and thyroid function at monthly intervals for 12 months. Iodine excretion in the immediate postpartum period did not differ between the 73 women who developed PPT and the antibody-negative controls. In women with PPT with hyperthyroidism, hypothyroidism, or hyperthyroidism followed by hypothyroidism, increased urinary iodine excretion was observed between 8 and 16 weeks postpartum, which preceded the hormonal disturbances among the women with hypothyroidism. The height of the rise in urinary iodine excretion during the first 20 weeks postpartum correlated with the serum free thyroxine levels (r = 0.61, p less than 0.001). Iodine intake is unlikely to affect the prevalence of PPT. However, these data show that the hyperthyroid phase of PPT is associated with a significant release of intrathyroidal iodine due to thyroid destruction and that the same process also occurs to a lesser extent before the hormonal disturbances associated with hypothyroid PPT.

Autoantibodies↗
PubMed1992

Reversible adrenocorticotropin deficiency due to probable autoimmune hypophysitis in a woman with postpartum thyroiditis.

The natural history and pathogenesis of lymphocytic hypophysitis remain poorly understood. We describe a 34-yr-old woman with postpartum thyroiditis and ACTH deficiency, studied at monthly intervals for 18 months after pregnancy. A significant titer of thyroid peroxidase autoantibodies was detected at 16 weeks gestation, and she was recruited into a prospective study of postpartum thyroid function. Four months postpartum she developed mild hyperthyroidism [free T4 (fT4), 27 pmol/L; TSH, less than 0.2 mU/L] and showed a rise in thyroid peroxidase and thyroglobulin autoantibodies. At 9 months postpartum, serum fT4 and fT3 levels were low normal (8.0 and 1.7 pmol/L, respectively), but TSH was not raised (0.4 mU/L). Subsequent investigation showed a low basal plasma cortisol level (28 nmol/L) in association with undetectable ACTH, and subnormal cortisol responses to depot Synacthen (535 nmol/L at 6 h) and hypoglycemia (peak, 145 nmol/L). FSH, LH, GH, and PRL function and computerized tomography of the pituitary were normal. Retrospective analysis of serum samples taken throughout the postpartum year showed developing hypocortisolemia between 3-9 months postpartum. Each sample was also tested for pituitary autoantibodies using a specific indirect immunofluorescent assay; none was detected. The ACTH deficiency recovered spontaneously, with normal cortisol responses to depot Synacthen (greater than 1380 at 6 h) and hypoglycemia (peak, 590) 14 and 18 months postpartum, respectively. This case illustrates that postpartum pituitary deficiencies are potentially reversible. The pattern of pituitary deficit and postpartum thyroiditis supported a diagnosis of autoimmune hypophysitis.

Adrenocorticotropic Hormone↗
PubMed1992

Postpartum thyroiditis: an organ specific syndrome which is not associated with a postpartum polyclonal B-cell activation.

Recent reports have detailed the presence of autoantibodies characteristic of non-organ specific autoimmune diseases in the serum of patients with autoimmune postpartum thyroiditis (PPT). These observations suggest that PPT could be part of a polyclonal B-cell activation postpartum. We have measured 4 non-organ specific autoantibodies (anti-DNA, anti-cardiolipin, anti-nuclear factor (ANF) and antibodies against extractable nuclear antigens (ENA)) together with autoantibodies against thyroglobulin and thyroid peroxidase in a group of PPT women at 4 time points during the first year postpartum (early, time of hyperthyroidism, time of hypothyroidism, late). Whilst 18/18 patients showed thyroid specific autoantibody changes there was only a low frequency of occurrence of the non-organ specific autoantibodies (ENA 2/18; ANF 1/18; anti-DNA 2/18; anti-dsDNA 0/18; anti-cardiolipin 0/18) and, when positive, the response was poor. We conclude that PPT is not associated with a polyclonal b-cell activation but is a postpartum rebound of a thyroid specific autoimmune phenomenon.

Antibodies, Antinuclear↗
PubMed1991

Interference in thyroid-function tests in postpartum thyroiditis.

Three women are described from a study of patients with postpartum thyroiditis whose sera gave spuriously increased concentrations of free thyroid hormone because of antibody binding of radiolabeled thyroxin (T4) and triiodothyronine (T3) analogs. All of the women showed increased serum concentrations of thyroid autoantibodies. The antibody binding of radiolabeled analogs and its effect on free T4 and free T3 assays disappeared by 48 weeks postpartum. Postpartum women who develop thyroid autoantibodies have approximately 2% prevalence of increased binding of radiolabeled analogs, which can result in an interference in thyroid hormone assays involving T4 and T3 analogs.

Autoantibodies↗
PubMed1990

Image statistics and the perception of apparent motion.

The short- and long-range apparent motion processes are discussed in terms of the statistical properties of images. It is argued that the short-range process, exemplified by the random-dot kinematogram, is primarily sensitive to the dipole statistics, whereas the long-range process, exemplified by illusory occlusion, is treated by the visual system primarily in terms of the tripole and higher statistical correlation functions. The studies incorporate the balanced dot, which is a unique stimulus element that permits high pass filtering while preserving detailed positional information. Low spatial frequencies are shown to be critical for texture segregation in random-dot kinematograms, independent of the grain size or number density of texture elements. Illusory path perception in the long-range process is shown not to require low spatial frequencies, but is sensitive rather to global temporal phase coherency. These results are interpreted in terms of the respective roles of the power and phase spectra in perceptual organization. The construction of balanced dots is discussed in detail.

Attention↗
PubMed1990

A long-term follow-up of postpartum thyroiditis.

To investigate the long-term outcome of postpartum thyroiditis (PPT), 43 patients with PPT and 171 control women were evaluated 3.5 (range 2-4) years postpartum. Ten (23%) PPT patients were hypothyroid compared to none of the controls (P less than 0.001). Factors associated with the development of hypothyroidism were high antimicrosomal antibody titre measured at 16 weeks gestation (P less than 0.01), severity of hypothyroid phase of PPT, multiparity, and a previous history of spontaneous abortion. The presence of microsomal antibody but no PPT in one pregnancy did not prevent the occurrence of PPT in the next pregnancy in two patients and a further five patients had PPT in two successive pregnancies. There was no association between HLA haplotype, family history of thyroid disease, smoking or frequency of oral contraception, and the development of long-term hypothyroidism after PPT. It is concluded that permanent hypothyroidism is an important sequel to PPT and patients with PPT should be followed up appropriately.

Adult↗
PubMed1990

Post-partum thyroiditis can be painful.

A patient with post-partum thyroiditis is described. She was a 22 year old with a negative family history of autoimmune thyroid disease who was noted to have a high titre of antithyroid microsomal antibody during pregnancy. She developed mild hyperthyroidism 8 weeks post-partum but at 12 weeks she had a mildly painful enlarged thyroid gland. At 20 weeks post-partum she had severe thyroidal pain with dysphagia. The thyroid was exquisitely tender to palpation. She was treated with L-thyroxine and the pain resolved within 4 weeks. This is the first report documenting pain in the thyroid as a feature of post-partum thyroiditis.

Adult↗
PubMed1989

The effect of chlorhexidine supplementation in a periodontal dressing.

Most commercial periodontal dressings claiming antibacterial activity lose this activity shortly after application. Chlorhexidine (CH) is an antibacterial agent with long-term activity in the oral cavity owing to its substantiveness and slow-release properties. In a double-blind split-mouth-designed clinical trial the effect of incorporating CH acetate in periodontal dressing was tested on wound healing after gingivectomy. Eleven patients, each needing at least two gingivectomies, constituted the test panel. Wound healing, as assessed by bleeding tendency after removal of dressing 7 days postoperatively was significantly delayed when control dressings were applied as compared with test dressings. Variables with regard to patient comfort also yielded results in favor of the test pack. Incorporation of antibacterial agents with high retention and slow release properties in the mouth in surgical dressings seems advantageous.

Adult↗
PubMed1988

Captopril-enhanced 99mTc DTPA scintigraphy in the detection of renal-artery stenosis.

The value of captopril-enhanced 99mTc DTPA scintigraphy as a screening test for renovascular disease was prospectively studied in 44 hypertensive patients suspected to have renal-artery stenosis. Renal impairment (plasma creatinine greater than 130 mumol/l) was present in 29 patients. At angiography 13 patients had unilateral stenosis, two bilateral stenosis, and 29 patients had no renovascular disease. Captopril induced a fall in split renal function in the kidney ipsilateral to the stenosis in all patients with unilateral disease (mean 52 +/- 23% to 44 +/- 21% of total renal function; P less than 0.001). A positive captopril scintigram (defined as a fall of 5% or more in split renal function) had a sensitivity of 85% and a specificity of 72% in the detection of unilateral renal-artery stenosis. Captopril-enhanced 99mTc DTPA scintigraphy is a promising non-invasive screening test for the detection of renal-artery stenosis.

Adult↗
PubMed1988

Intersubject variability in plasma theophylline levels after oral and intravenous administration in Jordanian patients with chronic obstructive pulmonary disease.

Plasma theophylline concentrations were determined in 151 Jordanian patients with chronic obstructive pulmonary disease. Mean plasma levels after oral administration were below the therapeutic range and significantly lower than after intravenous administration. Plasma levels in patients with congestive heart failure (CHF) were higher than in patients with no CHF. Trough plasma theophylline concentrations after intravenous administration in patients less than 18 years of age were significantly lower than in those aged 18-60 years. The overall results are in agreement with observations made in other ethnic groups.

Administration, Oral↗
PubMed1988

Effect of ofloxacin on the pharmacokinetics of a single intravenous theophylline dose.

The effect of ofloxacin taken for 8 days (200 mg twice daily) on the pharmacokinetics of a single intravenous dose of theophylline (4.3 mg/kg over 15 min) was studied in a crossover procedure among seven healthy male volunteers. Theophylline concentrations were measured serially for 10 h by the immunofluorescence polarization technique. No significant effect of ofloxacin was found on theophylline clearance, half-life, or volume of distribution. It is therefore concluded that ofloxacin and theophylline can be safely administered together.

Adult↗
PubMed1988

Pharmacokinetics of high and moderate intravenous doses of methotrexate.

The pharmacokinetic parameters of methotrexate in nine cancer patients receiving 250-2500 mg/day were investigated. Both elimination rate constants and half-lives were calculated using a two-compartmental open model. The plasma levels-time profiles revealed a biphasic response with a mean initial elimination half-life of 2.3 +/- 0.2 hours and a terminal elimination half-life of 32.2 +/- 7.2 hours.

Adolescent↗
PubMed1987

Spectrophotometric study of the photodecomposition kinetics of nifedipine.

Nifedipine is a photosensitive compound. Irradiation for 4 h under a fluorescent lamp placed 30 cm from a solution of nifedipine in 95% ethanol leads to complete photo-oxidation as determined spectrophotometrically. The disappearance of the reduced form and appearance of the oxidized form is best described by zero-order kinetics at concentrations higher than 4 x 10(-4) M. At lower concentrations pseudo-first order kinetics are followed. Monochromatic irradiation of nifedipine at wavelengths 400 to 700 nm in 25 nm increments showed no change in the absorbance at 280 nm, and, except for a hyperchromic effect at 237 nm, no other spectral changes were observed. Its photo-oxidation was dependent on the intensity of light and increased exponentially as solutions were irradiated progressively closer to a fluorescent light source. The pH studies showed that aqueous solutions of nifedipine photo-oxidized fastest at pH 2.

Drug Stability↗
PubMed1987

Changes in glutathione and its metabolizing enzymes in human erythrocytes and lymphocytes with age.

The levels of glutathione (GSH) and the activities of glutathione S-transferases (GST) and glutathione reductase (GSR) in human erythrocytes and lymphocytes were determined in three age groups (5-12, 25-40, 65-83 years). The levels of GSH in lymphocytes increased with age, however, its levels in erythrocytes reached a maximum in the middle age group. The activity of GST in erythrocytes and lymphocytes changed as a function of age in a pattern similar to the changes found for GSH levels. GSR activity increased from young to middle age in both erythrocytes and lymphocytes, but decreased again in the old age group.

Adult↗
PubMed1987

Changes in glutathione, glutathione reductase and glutathione-S-transferase as a function of cell concentration and age.

The activities of glutathione-S-transferase (GST) and glutathione reductase (GSR) in mouse lymphocytes as a function of cell concentration and age were determined. Lymphocytes from 2-, 9- and 24-month-old mice were isolated and the activity of GST was determined spectrophotometrically using 1-chloro-2,4-dinitrobenzene as the substrate. Lymphocyte concentrations of 0.44, 0.75 and 0.55 X 10(6) cells/ml were found to be optimal for assaying GST in 2-, 9- and 24-month-old mice, respectively. Determination of GSR activity was based on NADPH reduction of oxidized glutathione and cell concentrations of 0.29, 0.30 and 0.22 X 10(6) cells/ml were chosen for assaying the enzyme activity for the three age groups, respectively. Glutathione levels and GSR activity of mice lymphocytes were higher in 2- and 24-month-old mice as compared to 9-month-old animals. However, GST activity of mouse lymphocytes was low in 2- and 9-month-old mice and increased significantly in 24-month-old animals.

Aging↗
PubMed1987

Comparative determination of phenytoin in plasma by fluorescence polarization immunoassay and high performance liquid chromatography.

The need for careful monitoring of plasma concentrations of phenytoin during use of the drug in the treatment of epilepsy is well recognized; there can be great intersubject variation in the absorption rate and clearance rate of the drug, and its therapeutic ratio is narrow. In this study, two methods for determining plasma phenytoin concentrations were compared. One, based on fluorescence polarisation immunoassay (FPIA), is utilised in a commercially-available kit. The other, our own modification of a published procedure, was based on high performance liquid chromatography (HPLC). The accuracy and precision of both methods were evaluated, and the coefficients of variation (C.V.) were calculated. The C.V.'s ranged from 0.71 to 1.86% for the FPIA method, and from 2.81 to 8.69% for the HPLC method. Corresponding bias values were 1.20 to 1.60%, and 2.81 to 8.69%, respectively. A good correlation coefficient (0.977) was obtained, but estimated phenytoin concentrations were significantly higher (95% confidence level) using the HPLC method. We conclude that both methods perform adequately for clinical purposes. The HPLC method is, however, less expensive than the FPIA method.

Chromatography, High Pressure Liquid↗
PubMed1987

Glutathione, glutathione S-transferase and glutathione reductase in human erythrocytes and lymphocytes as a function of sex.

We review the role of glutathione (GSH) and its metabolizing enzymes, glutathione S-transferase (GST) and glutathione reductase (GSR) in drug metabolism and in the elimination of foreign compounds. Levels of GSH and the activity of these enzymes may be greatly influenced by drugs and other substances in the body. We therefore determined GSH levels and the activities of GST and GSR in human erythrocytes and lymphocytes in males and females in three age groups. There was no significant difference between males and females in the three age groups in respect of GSH levels and GST and GSR activities. GSH levels in erythrocytes were higher than those in lymphocytes when expressed per mg protein, but lower than those in lymphocytes when expressed per 10(6) cells. The activities of both GST and GSR were found to be higher in lymphocytes than in erythrocytes.

Adolescent↗