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Biomedical subjects

G Ahmed

Publications and source records attributed to G Ahmed.

At least 19 recordsLinked to original sources
PubMed2001

Understanding constraints to adolescent condom procurement: the case of urban Botswana.

Even when condoms are widely available and affordable, adolescents may be reluctant to obtain them. Hence, programme managers need to understand what determines youths' perceptions of access to condoms. This paper analyzes focus group and survey data on condom access conducted among male and female adolescents in urban Botswana. Although a majority of sexually experienced adolescents have purchased condoms from retail outlets, only about 50% have obtained condoms from health facilities, even though the latter distribute free condoms. This study shows that many adolescents perceive that access to condoms is more difficult from public sector outlets than for private sector outlets, because the public sector providers tend to question the adolescents' behaviour while the latter do not. To bypass this problem, males tend to obtain condoms from friends. However, females are reluctant to ask their friends for condoms because they fear that their friends may gossip about them. The results of this study indicate that adolescents' access to condoms can be improved by interventions that improve the quality of interaction between public sector providers and adolescents, destigmatize condom use, expand private sector condom distribution, and that use peer sales agents and educators.

Adolescent↗
PubMed2001

Primary thyroid lymphoma: a retrospective analysis of prognostic factors and treatment outcome for localized intermediate and high grade lymphoma.

Non-Hodgkin's lymphoma presenting in the thyroid gland is uncommon. A review of the King Faisal Specialist Hospital and Research Centre (KFSH & RC) experience was performed to assess treatment outcome and prognostic factors in this rare extranodal presentation of localized lymphoma. Sixty patients treated at KFSH & RC between 1975 and 1995 were identified, and their records were reviewed retrospectively. Eight patients who had stage III or IV disease, low grade, or did not complete their prescribed treatment were excluded from the study. There were 38 female and 14 male patients with a median age of 59.5 years at the time of diagnosis (range: 10-87 years). Thirty-five of the 52 patients underwent diagnostic partial or total thyroidectomy at other institutions based on a preoperative assumption of thyroid carcinoma. All 52 patients had non-Hodgkin's lymphoma of intermediate (94%) or high (6%) grade. Detailed staging was carried out in all patients; 16 patients (31%) had disease confined to the thyroid gland (stage IE), whereas 36 (69%) had associated disease in cervical lymph nodes and/or the mediastinum (stage IIE) disease. All patients were treated with curative intent. A total of 18 patients (35%) were treated with a single-modality treatment--radiotherapy alone in 2, chemotherapy alone in 13, and surgery alone in the remaining 3 patients. The majority of patients (34/52; 65%) were treated with a combined-modality approach. The overall relapse-free survival (RFS) and overall survival (OS) at 5 years were 72% and 88%, respectively. There were no significant differences in outcome between those treated with single-modality and those with combined-modality therapy. A univariate analysis showed that the presence of mediastinal lymph node involvement was the most important prognostic factor affecting both RFS and OS. Patients with Hashimoto thyroiditis and without "B" symptoms were found to have a significantly higher RFS without influence on the OS. However, patients who had a good performance status (PS) of 0, 1, and 2 were found to have a significantly higher overall survival in comparison to those with poor performance status. Age, sex, stage, histology, lactic acid dehydrogenase level, tumor bulk, and the treatment modality were not found to correlate with RFS or OS. Mediastinal involvement and PS were found to be the most important independent prognostic factors influencing RFS and OS.

Female↗
PubMed2001

Serum prostate-specific antigen as surrogate for the histological diagnosis of prostate cancer.

INTRODUCTION: To determine whether there is a cut-off value of serum prostate-specific antigen (PSA) which can be used confidently to make the diagnosis of prostate cancer, thereby obviating the need for biopsy. PATIENTS AND METHODS: During the period October 1991 to March 1998 the Department of Chemical Pathology at Tygerberg Hospital performed a total of 6,733 serum PSA assays on 3,960 patients. The histopathological and clinical diagnoses of these patients were obtained from records in the departments of Anatomical Pathology, Urological Oncology and Radiation Oncology. The serum PSA levels were correlated with the histopathology reports, using different PSA cut-off values ranging from 5 to 500 ng/ml, to calculate the sensitivity, specificity, and positive and negative predictive values of each cut-off value of PSA in predicting the presence of prostate cancer. RESULTS: In total, 3,837 (57%) of the 6,733 serum PSA assays were < or = 4 ng/ml, 1,045 (15.5%) of the assays were > or = 50 ng/ml, and 798 (11.9%) were > or = 100 ng/ml. Of the total of 3,960 individual patients, 531 (13.4%) had a serum PSA > or = 50 ng/ml and 423 (10.7%) had a PSA > or = 100 ng/ml. A serum PSA of > or = 30 ng/ml had a positive predictive value (PPV) of 90% at a specificity of 87% and sensitivity of 78%, while a PSA > or = 60 ng/ml had a PPV of 98% at a specificity of 98% and sensitivity of 65% for the presence of prostate cancer. The PPV reached 99% at a PSA > or = 100 ng/ml and 100% at a PSA > or = 500 ng/ml, with a specificity of 99% and 100%, but sensitivity of only 53% and 19%, respectively. CONCLUSIONS: A serum PSA > or = 60 ng/ml has a PPV of 98% for the presence of adenocarcinoma of the prostate, and may be used as a surrogate for histological diagnosis where facilities for obtaining prostatic biopsies are not readily available, thus decreasing costs and patient morbidity.

Aged↗
PubMed2001

High frequency shoot regeneration from nodal and shoot tip explants in Holarrhena antidysenterica L.

Shoot tip and nodal segment explants of Holarrhena antidysenterica when cultured on MS medium containing BAP (1.0-3.0 mg/l) with NAA (0.2-1.0 mg/l) and BAP (1.0-3.0 mg/l) with Kn. (0.2-1.0 mg/l) produced multiple shoots. Maximum multiple shoots was found in MS medium supplemented with BAP (2.0 mg/l) and NAA (0.5 mg/l). Subculture on the same medium resulted in rapid shoot multiplication at an average rate of 16 new shoots per subculture. Addition of urea (100 mg/l) in the medium increased the number of shoots up to 22 per culture. For best rooting, the shoots were excised from the culture flask and implanted individually on half strength MS medium with 0.5 mg/l each of IBA, IAA and NAA. After 20 days of transfer on root induction medium 95% rooting was achieved. Regenerated plantlets were successfully acclimatized and established in soil. About 90% of plantlets survived under open field conditions.

Apocynaceae↗
PubMed2000

Total synthesis of (+)-zaragozic acid C.

A total synthesis of (+)-zaragozic acid C is described. Key features of the synthesis are the use of a double Sharpless asymmetric dihydroxylation reaction of diene 6 to control stereochemistry at four contiguous stereocenters from C3 to C6; the introduction of the C1-side chain by reaction between the anion derived from the dithiane monosulfoxide 27 and the core aldehyde 12; a high yielding, acid-mediated simultaneous acetonide deprotection-dithiane removal-ketalization procedure leading exclusively to the 2, 8-dioxabicyclo[3.2.1]octane core 34; and a novel triple oxidation procedure allowing installation of the tricarboxylic acid.

Anticholesteremic Agents↗
PubMed2000

Contemporary patterns of adolescent sexuality in urban Botswana.

In Botswana, as in other areas in southern Africa, there is a growing concern about the risks associated with adolescent sexuality. To facilitate the design of policies that can address these problems, it is necessary to gain a thorough understanding of contemporary patterns of adolescent sexual behaviour, and the factors that affect them. This paper examines these issues using data from the 1995 Botswana Adolescent Reproductive Health Survey in conjunction with data from focus group discussions. The results suggest that adolescents become sexually active at an early age, and that many of them, males and females alike, have multiple sex partners. This early sexual initiation implies that adolescent reproductive health programmes should target youths aged 13 or younger. For school-based programmes this implies starting no later than Grade 6 or Standard 1, and preferably earlier. Young males appear to be a particularly vulnerable group that needs further attention. Adolescents perceive that teachers, peers and parents have the largest influence on their reproductive health attitudes. Schools appear to have the most potential for providing reproductive health information, because they reach youths both directly and indirectly by educating their peers. The results also show that male and female sexual behaviour is affected by different factors. Among males, having secondary education strongly increases the odds of being sexually active, presumably because such males make attractive partners. Among females, on the other hand, being in school significantly reduces the odds of being sexually active. This finding is consistent with the policy imposing a one-year school expulsion for pregnant schoolgirls, which was implemented as a deterrent to schoolgirl pregnancy.

Adolescent↗
PubMed2000

Congenital chylothorax.

The objective of this paper is a retrospective study of all infants treated for congenital chylothorax at the Royal Children's Hospital (RCH), Melbourne, Australia and King Fahad National Guard Hospital (KFNGH), Riyadh, Kingdom of Saudi Arabia. The charts of all infants with congenital chylothorax admitted to RCH over a period of 13 years, June 1982-August 1994, and admissions to KFNGH over a 7-year period, June 1992-August 1998 inclusive, were reviewed including management outcome and complications. There were 19 infants, 13 from RCH and 6 from KFNGH; 11 females and 8 males. Three infants were managed antenatally. Fifteen infants presented immediately after birth. Seven were born with hydrops fetalis, 6 infants had syndromes and 10 infants were born prematurely. Regular infant feeding formula and/or breast milk were used successfully in 12 infants, while in 7 infants medium chain triglycerides (MCT) rich formula was used. Sixteen infants were mechanically ventilated with 75% of them ventilated for < or = 28 days. Fifteen infants received total parenteral nutrition (TPN), and in 80% for < or = 32 days. Hydropic infants had longer duration of mechanical ventilation and hospital stay with mean (range) of 33.9 (3-120) and 115 (23-225) days, respectively, compared with 18 (1-62) and 34.3 (14-88) days for nonhydropic infants. Five infants underwent surgery with failure in four. Sepsis and bronchopulmonary dysplasia were the main complications. The survival rate was 100% regardless of the mode of therapy. The prognosis of Isolated congenital chylothorax in term, and preterm infants is good even in the presence of hydrops. Breast milk and/or regular infant feeding formula should be used initially before proceeding to MCT-rich formula, which may be necessary in some cases. Surgery should be considered if conservative management of congenital chylothorax fails after 4-5 weeks.

Chylothorax↗
PubMed1998

Congenital diaphragmatic hernia: experience with preoperative stabilization and delayed surgery without ECMO and inhaled nitric oxide.

Despite many advances in the management of congenital diaphragmatic hernia (CDH), the condition carries a mortality rate of 40-50% usually consequent to pulmonary hypoplasia and/or persistent pulmonary hypertension. Several centers have reported improved survival with preoperative stabilization and delayed surgery, which is now an accepted method of management. This is a retrospective analysis of all neonates with respiratory distress at birth due to CDH who were treated at our institution with neither extracorporeal membrane oxygenation nor nitric oxide being used. The medical records of all neonates with CDH and respiratory distress at birth who were treated at this institution from August 1, 1992 through March 1, 1997 were reviewed. There were 21 patients, 11 male and 10 female. There were 17 full-term and 4 premature infants; two premature infants at 30 and 34 weeks' gestation were not resuscitated because of severe associated congenital anomalies. Surgery was performed from 5 to 144 hr (mean 45 hr) in 18 infants. One infant died during preoperative stabilization from severe pulmonary hypoplasia and pulmonary hypertension and one infant died postoperatively from the same conditions. Seventeen of 19 infants (89.5%) survived and were discharged home. Three infants (17.6%) who failed to thrive due to severe gastroesophageal reflux (GER) required fundoplication. Eleven infants (64.7%) who had sepsis proven by blood culture responded satisfactorily to appropriate antibiotics. Preoperative stabilization and delayed surgery has been a satisfactory form of management in our series. The significant complication was sepsis, which must be addressed.

Bronchodilator Agents↗
PubMed1995

Mitochondrial ATPase: a target for paracetamol-induced hepatotoxicity.

We examined the effect of paracetamol treatment (650 mg/kg) on the function of ATPase from rat hepatic mitochondria. The drug treatment caused an overall 35% decrease in ATPase activity, with a complete loss of the high affinity component as determined by substrate kinetic studies. The Km for the intermediate and low affinity components decreased by about 30% without change in Vmax, which may represent a compensatory mechanism. The drug treatment also resulted in a dramatic decrease in the phase transition temperature by about 19 degrees C without affecting the energies of activation of the enzyme. Mitochondrial total phospholipid content increased significantly with a reciprocal decrease in the cholesterol content. The total phospholipid/cholesterol molar ration increased by 50% after paracetamol treatment. However, phospholipid composition (as % of total) of the mitochondria was unaltered.

Acetaminophen↗
PubMed1995

Phases of fluid and electrolyte homeostasis in the extremely low birth weight infant.

OBJECTIVE: We had shown previously that preterm infants undergo three phases of fluid and electrolyte homeostasis; prediuretic, diuretic, and postdiuretic. The objectives of the present study were: (1) to determine whether infants even more immature and infants cared for under thermal environmental conditions different from those previously studied also undergo these three phases; and (2) to relate these phases to changes in renal function. METHODS: Consecutive, timed urine collections were made during the first 5 days of life in 32 infants with birth weights of 1000 g or less. Infants were cared for in radiant warmers for 24 hours and then transferred to nonhumidified incubators. Diuresis was defined as urine flow rate (V) of 3 mL or more/kg per hour and weight loss of 0.8 g or more/kg per hour. The physiologic relationships among water and sodium balance, insensible water loss, arterial blood pressure, and renal function were made during the three phases. RESULTS: Twenty-eight (87%) of the 32 infants underwent the three homeostatic phases. The median ages of onset and cessation of diuresis were 25 and 96 hours, respectively. There was no correlation between onset of diuresis and change of thermal environment. During the prediuretic phase, V averaged 1.6 mL/kg per hour, and 17 of 28 infants had at least one collection period in which V was less than 1 mL/kg per hour; urinary sodium excretion was 0.1 mEq/kg per hour; the glomerular filtration rate (GFR) was 0.22 mL/kg per hour; fractional excretion of sodium (FENa) was 6.2%; and urine osmolality was dilute (221 mOsm/kg). During the diuretic phase, V and sodium excretion more than tripled; GFR and FENa doubled; and there was no change in urine osmolality. During postdiuresis, V and Na excretion decreased to values intermediate between the prediuretic and diuretic phases, and FENa fell to prediuretic levels, but there was no change in GFR or urine osmolality. There was poor correlation between blood pressure and GFR. Insensible water loss was high and variable during all phases, exceeding 190 mL/kg per day in the smallest infants. CONCLUSIONS: Extremely low birth weight infants manifest three phases of fluid and electrolyte homeostasis, as do more mature infants, independent of thermal environment. Diuresis and natriuresis are the result of abrupt increases in GFR and FENa. We speculate that this may be the result of expansion of the neonatal extracellular space as fetal lung fluid is reabsorbed.

Diuresis↗
PubMed1994

Impact of conflict on demographic factors and their importance in negotiated settlement in southern Africa.

"Though the concept of negotiated settlements gained its momentum in southern Africa--Angola, Mozambique, Namibia and South Africa--the full success of negotiations is yet to be seen in most of these countries.... Demographic consequences of conflicts are explained through a systemic model. The importance of demographic variables on negotiated settlement has also been explained the same way. There is no easy way out to overcome conflicts...but it is suggested that mutual consultation with opposition parties or minorities, or the suppressed people, would help ease many situations in Africa or elsewhere."

Africa↗
PubMed1992

Evidence that fin whales respond to the geomagnetic field during migration.

We challenge the hypothesis that fin whales use a magnetic sense to guide migration by testing for associations between geophysical parameters and the positions where fin whales were observed over the continental shelf off the northeastern United States. Monte Carlo simulations estimated the probability that the distribution of fin whale sighting was random with respect to bottom depth, bottom slope and the intensity and gradient of the geomagnetic field. The simulations demonstrated no overall association of sighting positions with any of these four geophysical parameters. Analysis of the data by season, however, demonstrated statistically reliable associations of sighting positions with areas of low geomagnetic intensity and gradient in winter and fall, respectively, but no association of sighting positions with bathymetric parameters in any season. An attempt to focus on migrating animals by excluding those observed feeding confirmed the associations of sighting positions with low geomagnetic intensity and gradient in winter and fall, respectively, and revealed additional associations with low geomagnetic gradients in winter and spring. These results are consistent with the hypothesis that fin whales, and perhaps other mysticete species, possess a magnetic sense that they use to guide migration.

Animals↗
PubMed1990

Characteristics of condom use and associated problems: experience in Bangladesh.

Data from the 1983 Bangladesh Condom User Survey (BCUS) are analyzed for patterns of condom use and various problems directly influencing their effectiveness. The survey was undertaken to explain an apparent gap between reports of the number of condoms distributed in certain areas compared with prevalence of users as reported in contraceptive prevalence surveys. These data are analyzed from behavioral and management perspectives to identify various factors influencing utilization, with potential implications for understanding and improving family planning and AIDS/STD prevention service systems. Patterns of use are related to differences in source of supply through public, free or private-priced systems, differences in urban or semi-rural place of residence, and differences in perceptions of men or women. The problem with condom use most often identified by the respondents was breakage.

Adult↗
PubMed1990

Experimental infection of Red Sokoto goats with Salmonella typhimurium.

Salmonella typhimurium infection was experimentally induced in goats by administering 2 x 10(10) organisms per os. The disease produced was characterized by pyrexia, diarrhoea and neutrophilia. One goat died from septicaemia. Somatic "0" agglutinins were detected 14 days post infection (p.i.). Excretion of organisms in faeces ceased by 6 weeks p.i. Goats which recovered from primary infection were refractory to a secondary challenge with 2 x 10(11) organisms. The results indicate that in the absence of signs of ill-health, the detection of neutrophilia and "0" agglutinins and isolation of Salmonella organisms from faeces mainly served as evidence of recent infection.

Animals↗
PubMed1982

Clinical and field studies of human lactation: methodological considerations.

A variety of studies has been completed to assess selected methods that are presently being used or might potentially be used to evaluate lactation performance. During 64 test-weighings of infants before and after the consumption of a known amount of milk, the mean +/- SD "recovery" of milk ingestion was 94.9 +/- 13.2%. The weight of milk extracted by a mechanical pump was approximately 7% greater than the amount measured during test-weighings of infant of the same women within periods of 1 wk. To evaluate the possibility of performing abbreviated studies in field settings, the proportion of 24-h milk consumption received during 12 daytime hours was measured by test-weighings. Daytime consumption ranged from 46 to 58% of 24-h consumption (mean +/- SD = 52 +/- 3%). Attempts to predict the amount of milk consumption during 341 daytime studies from the age of infants and their frequency and duration of feedings met with limited success. Although each independent variable was significantly correlated with the amount consumed (multiple r = 0.69, p less than 0.001), the SE of the estimate (Sy.x) was relatively large. The effects of time of day and side of extraction on the volume and composition of extracted milk were determined during 24-h studies of seven women. There were significant changes in the concentration of fat (p less than 0.001) and nitrogen (p = 0.003) during the day and significant differences in the concentrations of fat (p = 0.04) and lactose (p = 0.04) and in the volume (p less than 0.001) of milk produced by each breast. The importance of these findings for the planning and interpretation of studies of human lactation is discussed.

Adolescent↗
PubMed1981

Relationship of the xylose absorption status of children in Bangladesh to their absorption of macronutrients from local diets.

We compared the results of xylose absorption tests from 31 asymptomatic Bangladeshi children with their ability to absorb macronutrients from cereal-vegetable diets, as determined by metabolic balance studies. The xylose test results ranged from 9.8 to 37.0% excretion of the ingested dose, with more than half of the values less than 20% excretion. Nevertheless, the apparent absorption of macronutrients during 7-day balance studies ranged from 89.8 to 97.7% of intake for carbohydrate, 81.7 to 98.7% for fat, and 47.3 to 78.9% for nitrogen. There was a statistically significant correlation between the xylose test results and apparent carbohydrate absorption for one diet group only (r = 0.76, p less than 0.05), but not between the xylose results and other indicators of intestinal function of nutrition status. We conclude that diminished absorption of xylose, which is commonly recognized among asymptomatic residents of the tropics, does not necessarily indicate impaired absorption of macronutrients from the customary diet. Therefore, tropical enteropathy may not have major nutritional significance for those individuals with manifestations of the syndrome.

Bangladesh↗