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Biomedical subjects

S Ahmed

Publications and source records attributed to S Ahmed.

At least 55 records · Page 3Linked to original sources
PubMed2004

Extended-spectrum beta-lactamases (ESbLs): characterization, epidemiology and detection.

Beta-lactamases of Enterobacteriaceae are the most important mechanism of resistance against beta-lactam drugs. Two types of beta-lactamases can confer resistance against 3rd generation cephalosporins. Chromosomally mediated beta-lactamases are inducible and are not inhibited by clavulanic acid. Resistance due to these enzymes is non-transferable. The 2nd type of enzyme is plasmid-mediated beta-lactamases, which are inhibited by clavulanic acid. These enzymes are more important clinically as these can be transferred between various species of Enterobacteriaceae. These enzymes are called extended-spectrum beta-lactamases (ESBLs). ESBL-producing Enterobacteriaceae have been responsible for numerous outbreaks of infection throughout the world and pose challenging infection control issues. Antibacterial choice is often complicated by multi-resistance. ESBLs can confer resistance against all beta-lactam drugs except carbapenems and cephamycins. Nursing home patients may be an important reservoir of ESBL-containing multiple antibiotic-resistant organisms. Use of broad-spectrum oral antibiotics and probably poor infection control practices may facilitate spread of this plasmid-mediated resistance. In addition to known populations at risk, ambulatory patients with chronic conditions represent another patient population that may harbor ESBL-producing organisms. Various methods can be used for detection of ESBLs in the laboratory. These tests include double disc diffusion test, Vitek ESBL test, E Tests, MIC Determination, genetic method, and isoelectric focusing (IEF).

Anti-Bacterial Agents↗
PubMed2004

Neonatal 5HT activity antagonizes the masculinizing effect of testosterone on the luteinizing hormone release response to gonadal steroids and on brain structures in rats.

Hypothalamic 5HT concentrations are transiently lower in male compared to female Wistar rats in the second week post partum (pp) and our previous findings have shown that pharmacologically potentiating 5HT activity over this period feminizes certain aspects of sexually differentiated behaviours in adult males and androgenized females. In order to investigate whether neonatal testosterone and 5HT interact to influence physiological and morphological brain sexual differences, females, androgenized females and males were treated with the 5HT2 agonist (-) [2,5 dimethoxy-4-iodophenyl]-2-amino propane HCl [(-) DOI], over days 8-16 pp. In androgenized females (250 microg testosterone proprionate, day 2 pp) (-) DOI prevented the delay in vaginal opening, but did not prevent the androgen-induced constant oestrus in females treated with 100 microg TP, day 2 pp. (-) DOI overcame the neonatal androgen effect in suppressing the positive feedback of ovarian steroids in a few males and androgenized females. (-) DOI had a feminizing effect on the volume of the anteroventral periventricular nucleus (normally smaller in males), by significantly increasing its volume in male and androgenized females. It also had a significant antagonistic effect on the testosterone-induced increase in the volume of the sexually dimorphic nucleus of the preoptic area in males and androgenized females. These findings support the view that raised 5HT activity in the second week of life antagonizes the masculinizing effect of neonatal testosterone.

Animals↗
PubMed2004

Methanol poisoning: diagnosis and management. A case report.

Methanol poisoning is an uncommon but potent central nervous system toxin. The diagnosis and the management of its sequelae remain a challenge to clinicians. A case is hereby presented in which computed tomography of the brain played an important role in making the diagnosis due to poor patient's history and unavailability of methanol assay. Parkinsonism and visual sequelae are well-recognised complications in the survivors. This patient developed parkinsonism in the form of mainly severe tremors and mild rigidity. He benefited from treatment on amantadine.

Adult↗
PubMed2004

Determinants of universal adolescent hepatitis B vaccine uptake.

The UK is currently considering the introduction of universal hepatitis B vaccination. This study of determinants of vaccine uptake among school based adolescents shows that living in areas of high deprivation, commonly associated with injecting drug risk behaviours, was the most important factor, with statistically significant lower odds of receiving three doses. This was less pronounced for receipt of two doses. Thus, there are implications for future policy; if universal vaccination is approved, a licensed two dose schedule would be most appropriate in this setting.

Adolescent↗
PubMed2004

Neurophysiology in clinical practice.

Clinical neurophysiology is concerned with the recording of generation and propagation of electrical potentials of nerve and muscle cells. It can provide important information about brain and neuromuscular disorders. Electro encephalogram (EEG), Evoked potentials (EP), Nerve conduction study (NCS) and electromyogram (EMG) are the four main techniques used in clinical neurophysiology. EEG reflects the electrical activity arising from the cerebral cortex. Evoked Potentials are measurements of classic stimulus response. VEP, SSEP and BSAEP are most useful in diagnosing Multiple Sclerosis, Plexus lesions and 8(th) cranial nerve tumor, CP angle tumor respectively. Nerve conduction studies are the measurement of velocity of nerve impulse. It gives information about the lesion of a myelinated nerve. Electromyogram gives information about the integrity of innervations, condition of neuromuscular junctions and also condition of the muscle fiber itself.

Electroencephalography↗
PubMed2004

Urinary iodine status and thyroid dysfunction: a Bangladesh perspective.

Iodine deficiency is endemic in Bangladesh. Compulsory iodization of table salt was introduced since 1993 to prevent and improve thyroid disorders in the country. Urinary iodine status, thyroid function and antithyroid antibodies were studied in 397 newly diagnosed thyroid patients and 94 age-sex matched controls. Among thyroid patients, 96 were hyperthyroid, 185 euthyroid and 116 hypothyroid. Mean and median urinary iodine were higher (p=0.075) in thyroid patients (26.13+/-0.91 and 23.03) than controls (22.65+/-1.47 and 18.59); in hyperthyroid and euthyroid than hypothyroid (p=0.020); in multinodular (28.08+/-2.80 and 26.94) and diffuse (27.35+/-1.19 and 26.71) goitre than uninodular (23.91+/-2.37 and 19.14) and nongoitrous (NG, 21.5+/-2.05 and 18.27) (p=0.098) patients but no sex difference (p=0.466). Antimicrosomal (26.7%) and antithyroglobulin (34%) antibodies were more frequently positive among thyroid patients than controls (6.4% and 12.8% respectively) (p=0.00002 and p=0.00005 respectively). Antibody positivity was higher in diffuse (82/228) and multinodular (20/47) goitre than nongoitrous (20/56) and uninodular (13/66) goitre (p=0.046) as well as in hypothyroid (55.2%) and hyperthyroid (36.5%) than euthyroid (19.5%) patients (P<0.001). Urinary iodine correlated neither with antimicrosomal (thyroid patients: p=0.597 and control: p=0.112) nor with antithyroglobulin (thyroid patients: p=0.388 and control: p=0.195) antibody. Thyroid autoimmunity and dysfunction seems common; and interaction of salt iodization with iodine status and thyroid disorders may be important in Bangladesh.

Adult↗
PubMed2003

Low-risk persistent gestational trophoblastic disease treated with low-dose methotrexate: efficacy, acute and long-term effects.

The aim of this study was to evaluate the efficacy and toxicity of low-dose methotrexate with folinic acid rescue in a large series of consecutively treated patients with low-risk persistent gestational trophoblastic disease. Between January 1987 and December 2000, 250 patients were treated with intramuscular methotrexate (50 mg on alternate days 1, 3, 5, 7) with folinic acid (7.5 mg orally on alternate days 2, 4, 6, 8) rescue. The overall complete response rate without recurrence was 72% for first-line treatment and 95% for those who required second-line chemotherapy. Eight women (3.2%) had recurrence following remission and two (0.8%) had new moles. Two women (0.8%) died of their disease giving an overall cure of 99%. Only 10 women (4%) experienced grade III/IV toxicity during the first course of treatment and 13 women (5.2%) subsequently. Toxicity included mucositis and stomatitis, pleuritic chest pain, thrombocytopenia, uterine bleeding, abdominal pain, liver function changes, rash and pericardial effusion. A total of 59 women (23.6%) required second-line chemotherapy; 48 women had methotrexate resistance, eight had methotrexate toxicity and an empirical decision to change therapy was made in three. In all, 11 women (4.4%) had a hysterectomy before, during or after treatment; 141 women (56.4%) became pregnant following treatment: in 128 (90.7%), the outcome was successful. Methotrexate with folinic acid rescue is an effective treatment for low-risk persistent trophoblastic disease. It has minimal severe toxicity, excellent cure rates and does not appear to affect fertility.

Adolescent↗
PubMed2003

Thrombotic thrombocytopenic purpura: a rare cause of thrombocytopenia in HIV-infected hemophiliacs.

Thrombocytopenia is a common complication in human immunodeficiency virus (HIV)-infected hemophiliacs. The etiology is multifactorial and a majority of the patients with hemophilia exhibit a decreased platelet count within 10 years of seroconversion. Thrombocytopenia in these patients is associated with a high risk of bleeding and death. Thrombotic microangiopathy causing thrombocytopenia in HIV-infected hemophiliacs is extremely rare. We describe an HIV-infected hemophilic patient who presented with bleeding, renal insufficiency, and thrombocytopenia. Platelet transfusion resulted in deterioration of clinical condition. Examination of blood smears demonstrated a microangiopathic process. The patient responded well to plasmapheresis with normalization of platelet and renal function. Thrombotic thrombocytopenic purpura should be suspected in HIV-infected hemophiliacs who present with a new onset of thrombocytopenia and anemia as delay in treatment may result in fatal sequelae.

Adult↗
PubMed2003

Branching fractions of tau leptons to three charged hadrons.

From electron-positron collision data collected with the CLEO detector operating at Cornell Electron Storage Ring near sqrt[s]=10.6 GeV, improved measurements of the branching fractions for tau decays into three explicitly identified hadrons and a neutrino are presented as B(tau(-)-->pi(-)pi(+)pi(-)nu(tau))=(9.13+/-0.05+/-0.46)%, B(tau(-)-->K-pi(+)pi(-)nu(tau))=(3.84+/-0.14+/-0.38) x 10(-3), B(tau(-)-->K-K+pi(-)nu(tau))=(1.55+/-0.06+/-0.09) x 10(-3), and B(tau(-)-->K-K+K-nu(tau))<3.7 x 10(-5) at 90% C.L., where the uncertainties are statistical and systematic, respectively.

Journal Article↗
PubMed2003

Risk factors as the basis for triage in low-resource cervical cancer screening programs.

OBJECTIVES: Several studies have shown impressive sensitivity and specificity of visual inspection using acetic acid wash (VIA) in detecting cervical dysplasia. This study examines how risk-factor based triage, using clinical history-taking to limit the testing to those at highest risk of disease, improves the clinical utility of VIA. METHODS: The study population included 2206 woman aged 25-56 from peri-urban primary care clinics in Zimbabwe. Three risk factors variables [age, lifetime number of sexual partners and history of a sexually transmitted infection (STI)] were selected as the basis for computer-simulated patient triage. Criteria for selecting risk factors were biological relevance, programmatic feasibility, historical evidence in the scientific literature as a risk factor for cervical cancer and a significant (P<0.05) predictor of dysplasia in this study population. Predictive values for VIA were calculated on subgroups of women with combinations of the three risk factors and then compared with the predictive value of VIA calculated on the full study population. RESULTS: The positive predictive value (PPV) among women with all three risk factors (30.2%) was 1.6 times higher than that of all study women and 4.5 times higher than women with none of the three risk factors (4.1%). Additionally, the PPV was slightly (30%) higher than that obtained from computer-simulated serial testing using VIA as the primary test followed by HPV testing (27.4%). CONCLUSION: Clinical history-taking could provide the basis for patient triage to increase the clinical utility of VIA. Such an approach could also serve to prioritize who gets tested first in low-resource countries with high disease prevalence that are struggling to strengthen national cervical cancer prevention programs.

Acetic Acid↗
PubMed2003

Local differentiation in Plasmodium falciparum drug resistance genes in Sudan.

Studies of population genetic structure of parasites can be used to infer which parasite genes are under selection. Here, the population structure of 4 genes associated with drug resistance of Plasmodium falciparum (the chloroquine resistance transporter, pfcrt, dihydrofolate reductase, dhfr, dihydropteroate synthase, dhps, and multi-drug resistance, pfmdr-1) were examined in parasite populations in 3 villages in eastern Sudan and in an urban area of Khartoum, the capital. In order to differentiate the effects of drug selection from neutral influences on population structure, parasites were also genotyped for 3 putatively neutral microsatellite loci (polyalpha, TA81 and pfg377), and for 2 antigenic loci that are either under balancing selection or neutral, merozoite surface protein 1 and 2, (MSP-1 and MSP-2). Cross-sectional surveys were carried out during the peak transmission (wet) season and in the ensuing dry season. No significant variation in frequencies of MSP-1 and MSP-2 alleles was seen among villages in the eastern region and between the villages and Khartoum, nor between the wet and dry season. However, the drug resistance genes, pfmdr-1, pfcrt and dhfr and to a lesser extent the microsatellite loci showed high FST values when comparing villages with Khartoum, indicating strong geographical differentiation at these loci. Moreover, variation in frequencies of the drug resistance genes, pfmdr-1, pfcrt and dhfr, was observed between the wet and dry season. These differences most probably reflect the variation in drug pressure between each region, and in drug usage between the wet and dry season in a given region.

Adult↗
PubMed2003

Pulmonary manifestations of sickle cell disease.

Pulmonary complications account for significant morbidity and mortality in patients with sickle cell disease. Clinical lung involvement manifests in two major forms: the acute chest syndrome and sickle cell chronic lung disease. Acute chest syndrome is characterised by fever, chest pain, and appearance of a new infiltrate on chest radiograph. Sickle cell chronic lung disease, on the other hand, manifests as radiographic interstitial abnormalities, impaired pulmonary function, and, in its most severe form, by the evidence of pulmonary hypertension. Progress has been made in understanding the pathophysiology and management of these complications. In this review the current knowledge of the mechanism, diagnosis, and treatment of pulmonary complications of sickle cell disease are discussed.

Acute Disease↗
PubMed2003

Development of a vibratory microinjection method.

To reduce cellular damage by pronuclear microinjection and nuclear transfer, we have recently developed a vibratory microinjection method. A micropipette was fixed to a piezoelectric ceramic with a resonance frequency of 70 kHz. When this micropipette was vibrated, it easily entered a mouse-fertilized egg without any sharp depression of the cell body, whereas a sharp, deep depression at the insertion site was observed when the micropipette was not vibrated. A depression rate defined as a rate of a depth of depression over an original cell diameter was utilized as an index of cellular deformation. The depression rates with and without vibration were 11.1 +/- 5.2% (N = 24) and 40.4 +/- 8.8% (N = 16), respectively (P < 0.0001, Student's t-test). In conclusion, the vibratory microinjection method is a new, useful option for gene transfer because it resulted in much less cellular deformation, therefore implicating less cellular damage.

Animals↗
PubMed2003

The immune response of guinea pigs and buffalo calves to the locally prepared Brucella abortus strain 19 vaccine.

Brucella abortus vaccine was prepared from strain 19 imported from Germany. The vaccine induced a good immune response in guinea pigs as evidenced by a serological titre of 328 international units (IU)/ml 10 days post-vaccination. Vaccinated guinea pigs also withstood an experimental challenge of 5,000 colony-forming units of a locally isolated virulent B. abortus strain. This vaccine, containing 7 x 10(10) viable organisms, induced a significant immune response in 8 to 10.5 month old female buffalo calves. Significant serum agglutination test (SAT) titres were seen on day 7 following vaccination. The highest SAT titres were observed on day 14 post-vaccination and the titres started declining thereafter. The rate of decrease was slow from day 14 to day 49 post-vaccination; however, a rapid decrease in titres was seen from day 49 to day 91 post-vaccination. Negligible SAT titres were observed on day 91 post-vaccination. Specific immunoglobulin G titres, as measured by 2-mercaptoethanol treated SAT, also followed a similar trend and the titre of all five of the calves that were vaccinated became zero on day 91 post-vaccination.

Animals↗
PubMed2003

Serum calcium in normal pregnant women.

A prospective case-control study was done to determine any difference of serum calcium levels in pregnant women in third trimester and non-pregnant women. Serum calcium levels were determined in 30 normal non-gravid women and 30 women with normal pregnancies during third trimester with age range of 17-35 years. The mean serum calcium levels were found to be significantly lower in normal pregnant woman in third trimester than that of normal non-pregnant controls.

Adolescent↗