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Biomedical subjects

I Ahmed

Publications and source records attributed to I Ahmed.

At least 127 records · Page 7Linked to original sources
PubMed1997

The effects of clozapine on cognitive functioning in treatment-resistant schizophrenic patients.

This study examined the cognitive functioning of 10 treatment-resistant schizophrenic patients after a minimum of a 1-year trial on clozapine. Results indicated significant improvements on prorated Wechsler Adult Intelligence Scale-Revised (WAIS-R) Full Scale, Verbal, and Performance IQs and on the WAIS-R Similarities and Digit Symbol subtests. A trend was also found for improvement on the Wisconsin Card Sorting Test. It was concluded that clozapine treatment is associated with global cognitive improvements in patients with treatment-resistant schizophrenia. Clozapine treatment may also improve performance on the Wisconsin Card Sorting Test in a subset of patients. Improvement did not appear to be related to the reduction of any cognitive effects of the typical neuroleptics upon their discontinuation.

Adult↗
PubMed1997

Intravenous immunoglobulin-induced lichenoid dermatitis: a unique adverse reaction.

Intravenous immunoglobulin (IVIG) therapy has been used to treat various diseases. Generalized allergic reactions (types I, II, and III) to IVIG are uncommon and are usually related to the rate of infusion. Cutaneous reactions have been anecdotally described. Herein we describe a 73-year-old man with Sjögren's syndrome who had development of a lichenoid cutaneous eruption after administration of IVIG therapy. CD3 immunostaining demonstrated the overwhelming presence of T lymphocytes within a lesional skin biopsy specimen, and thus we present an alternative cell-mediated immune mechanism (type IV) by which allergic reactions to IVIG may occur.

Aged↗
PubMed1997

Malignant melanoma: prognostic indicators.

The incidence of cutaneous malignant melanoma in the Caucasian population has continued to increase at an alarming rate and is expected to be 1 in 75 by the year 2000. Within the medical community, these trends have prompted an interest in factors that potentially influence the biologic activity of such lesions. Several clinical and pathologic variables have been identified that affect the progression and behavior of melanoma. On the basis of multivariate analysis, the most important factors for predicting survival in patients with stage I and II melanomas are tumor thickness, presence of ulceration, and anatomic site of the primary tumor (the prognosis is poorer with head and neck lesions than with extremity lesions). For patients with stage III melanomas, all the foregoing factors plus the extent of nodal disease are of prognostic importance. For patients with stage IV melanomas, the main prognostic factors are the number of metastatic lesions and the site of metastatic involvement (visceral lesions portend a poor outcome).

Age Factors↗
PubMed1997

Arsenic on tap.

Explore the source record for details and available documents.

Asia↗
PubMed1996

Effect of bitter melon (Momordica charantia) fruit juice on the hepatic cytochrome P450-dependent monooxygenases and glutathione S-transferases in streptozotocin-induced diabetic rats.

Bitter melon (Momordica charantia), commonly known as karela, has been reported to have hypoglycemic, antiviral, antidiabetic, and antitumor activities. In the present study, we have investigated the effects of oral feeding of karela fruit juice on the hepatic cytochrome P450 (CYP) and glutathione S-transferase (GST) drug-metabolizing enzymes in the streptozotocin (STZ)-induced diabetic rat. Hepatic CYP contents, ethoxycoumarin-O-deethylase (ECOD), ethoxyresorufin-O-deethylase (EROD), aniline hydroxylase (AH), and aminopyrene N-demethylase (APD) activities were measured in control, diabetic, and karela juice fed animals. Diabetic rats exhibited a 50-100% increase in AH and EROD activities that was reversed by karela juice feeding. In addition, a decrease (17-20%) in the activities of APD and ECOD was observed in diabetic rat liver. Feeding of karela juice to the diabetic animals brought the level of APD close to that of control animals, while ECOD was further reduced to 60% of the control value. The cytosolic glutathione concentration was decreased in diabetic rats, and karela juice feeding normalized the effect. However, an increase (of 20-30%) in the GST activity was observed in both diabetic and karela juice fed rats. Western immunoblot analysis of CYP and GST isozymes exhibited a differential response during diabetes. The expression of CYP1A1, 2B1, 2E1, 3A4, and 4A2 in diabetes, while a decrease in GST mu was observed. Our results suggest that the changes in hepatic phase I and phase II drug-metabolizing enzyme activities in the STZ-induced diabetic animals may be associated with the altered expression of different CYP and GST isozymes. In addition, we have also observed that karela does not always reverse the effects on drug-metabolizing enzymes in STZ-induced diabetes.

Animals↗
PubMed1996

Heterocyclic steroids: synthesis of steroidal selena, tellura, and thialactones of estrane series.

A successful approach in the synthesis of 3 beta-acetoxy-17a-selena-D-homo-1,3,5(10)-estratrien-17 -one (5), 3 beta-acetoxy-17a tellura-D-homo-1,3,5(10)-estratrien-17-one (6), and 3 beta-acetoxy-17a-thia-D-homo-1,3,5(10)-estratrien-17-one (7) was achieved from 3 beta-acetoxy-1,3,5(10)-estratrien-17-one (1). The Baeyer-Villiger reaction of 3 beta-acetoxy-1,3,5(10)-estratrien-17-one (1) with perbenzoic acid afforded 3 beta-acetoxy-17a-oxa-D-homo-1,3,5(10)-estratrien-17-one (2), which on reaction with hydrobromic acid gave 3 beta-acetoxy-seco-13-bromo-1,3,5(10)-estratrien-16-oic acid (3). Treatment of bromo acid (3) with thionyl chloride gave 3 beta-acetoxy-seco-13-bromo-1,3,5(10)-estratrien-17 acid chloride (4), whose reaction with Se and Te in the presence of sodium borohydride gave the desired products 5 and 6. Reaction of 3 beta-acetoxy-seco-13-bromo-1,3,5(10)-estratrien-17 acid chloride (4) with sodium sulfide gave the thia lactone derivative (7).

Molecular Structure↗
PubMed1996

Corticotrophin-releasing hormone receptor type 1: generation and characterization of polyclonal antipeptide antibodies and their localization in pituitary cells and cortical neurones in vitro.

Corticotrophin-releasing hormone (CRH) is a 41 amino acid neuropeptide which plays a major role in regulating the endocrine response to stress. CRH acts by first binding to specific receptors on the plasma membrane of target cells. A CRH receptor from a human corticotroph adenoma and rat brain has recently been cloned (CRH-R1). In this paper, we have chosen three different peptide sequences within the CRH-R1 molecule which bear no similarity to other members of this receptor subfamily (or indeed any known protein) and which are likely to be exposed on the surface of the native protein, for antibody production. Some of these fragments produced antipeptide antibodies of good titre which cross-reacted with the CRH-R1 receptor expressed in transiently transfected COS-7 cells and in tissue extracts from rat cerebellum, cortex, pituitary gland and human myometrium, both in Western blots and in liquid-phase radioimmunoassay. We used immunofluorescence techniques to localize the CRH receptor in transiently transfected COS-7 cells, primary cultures of rat anterior pituitary (AP) cells, the corticotroph-tumour cells AtT20 D16-16 and cortical neurons in primary culture. Our results indicate IR-CRH-R1 receptors have a punctate distribution on the plasma membrane of AP cells and AtT20 D16-16 cells. Whilst in AP cells their appearance is a fine punctate pattern, in AtT20 cells, they appear as large patches which could account for receptor clusters. Within primary cortical neurons, their distribution does not appear to be polarized. Our results suggest that distribution of CRH-R1 receptors within the different cell-types investigated depends not only on the amino acid sequence but also on cellular factors.

Animals↗
PubMed1996

Comparative studies on IFAT, ELISA & DAT for serodiagnosis of visceral leishmaniasis in Bangladesh.

The purpose of the study was to estimate the specificity and sensitivity of different serological methods for the diagnosis of visceral leishmaniasis in Bangladesh. Blood samples from 155 suspected kala-azar patients together with 80 sick subjects and 50 healthy subjects from the endemic areas were collected. Out of the 155 suspected kala-azar patients, bone marrow were collected from 126 patients. All bone marrow samples were examined by direct microscopy. 92 bone marrow samples were also examined by culture method. Blood samples were examined by various serological tests. Out of 126 marrow samples, LD bodies were present by microscopy in 77 (61.1%) cases and out of 92 marrow samples, cultures for LD bodies were positive in 33 (35.9%) cases. All the three serological tests (IFAT, ELISA & DAT) were positive in all parasitologically positive kala-azar patients. They were also positive in seven (15.5%) out of 45 parasitologically negative cases and 10 (34.4%) out of remaining 29 cases in whom bone marrow samples were not available. Thus the serological tests proved to be simple, non-invasive, highly sensitive and specific methods for the diagnosis of visceral leishmaniasis. DAT is the simplest of these serological tests, although these tests did not differ in sensitivity and specificity.

Agglutination Tests↗
PubMed1996

Pamidronate infusions for the treatment of Paget's disease of bone.

Effective pamidronate dosages in Paget's disease of bone have not yet been determined. We prospectively compared two pamidronate dosages (60 mg and 120 mg) in 26 patients whose baseline alkaline phosphatase level was at least two-fold the upper limit of normal. Pamidronate was given as three-hour infusions of 60 mg each. Follow-up was two years. The two groups were comparable at baseline except for higher alkaline phosphatase and hydroxyproline levels in the group treated with 120 mg pamidronate. Efficacy on laboratory parameters was greater in the higher dosage group. Osteocalcin levels showed little change. In both dosage groups, alkaline phosphatase levels fell significantly versus baseline, and the difference persisted throughout the two-year follow-up. Urinary hydroxyproline excretion remained significantly reduced versus baseline during the first 12 months and rose subsequently. A return to normal of the two study parameters six months after treatment was associated with longer duration of the biologic treatment response. A survival curve analysis confirmed this finding and suggested that a return to normal of laboratory parameters was predictive of clinical remission. The drug was well tolerated. Adverse effects were mild and similar to those recorded during earlier studies.

Aged↗
PubMed1995

Structure of CuB in the binuclear heme-copper center of the cytochrome aa3-type quinol oxidase from Bacillus subtilis: an ENDOR and EXAFS study.

We have studied the structure of the CuB site in the binuclear heme-copper center of the fully oxidized form of the quinol-oxidizing cytochrome aa3-600 from Bacillus subtilis by EXAFS and ENDOR spectroscopy. This enzyme is member of the large superfamily of heme-copper respiratory oxidases, which catalyze the reduction of dioxygen to water and link it to translocation of protons across the bacterial or mitochondrial membrane. The EXAFS of the CuB site strongly suggests tetragonal coordination by two or three histidines with one or two O/N donor ligands. There are some indications that a Cl- ion might fractionally occupy substitution-labile sites, although the majority of enzyme molecules did not contain any heavy (second row) scatters, indicative of a Cl- (or S) bridge between the heme iron and CuB [cf. Powers, L., et al. (1994) Biochim. Biophys. Acta 1183, 504-512]. Proton ENDOR spectroscopy of the CuB site in 1H2O and 2H2O media showed evidence of an oxygenous copper ligand with an exchangeable proton. 14N ENDOR revealed three inequivalent nitrogenous ligands with hyperfine coupling constants consistent with histidines. Together, these results strongly suggest that the fully oxidized enzyme has a low-symmetry, tetragonal CuB site with three histidine nitrogens and one oxygen as ligands, the latter with an exchangeable proton(s). The identity and assignment of these ligands are discussed.

Bacillus subtilis↗
PubMed1995

Prenatal diagnosis of familial ring 21 chromosome.

Ring chromosome 21 is a rare chromosome anomaly often associated with mental retardation and dysmorphic features. Less commonly, the ring chromosome can be familial and associated with a normal phenotype. Phenotypically normal female carriers, however, are at increased risk of having children with Down syndrome, mosaic monosomy 21, and variable duplication or deletion of chromosome 21. Because of the relative mitotic and meiotic instability of ring chromosomes, abnormal cytogenetic findings encountered during prenatal diagnosis may not reflect the true genetic status of the fetus. This is a report of a phenotypically normal female carrier of a familial ring 21 chromosome. Prenatal diagnosis on her twin pregnancy revealed a mosaic 46,XX,r(21)(p13;q22) (77 per cent)/45,XX,-21 in one fetus and a normal male karyotype in the second. The pregnancy was carried to term. Both infants are completely normal, with a non-mosaic ring 21 karyotype from the lymphocytes of one twin. The diagnostic uncertainty and problematic genetic counselling related to fetal cytogenetic abnormalities are the subjects of this report.

Adult↗
PubMed1995

Flavonoid glycosides and an anthraquinone from Rumex chalepensis.

Besides rutin, quercetin 3-rhamnoside and kaempferol 3-rhamnosyl(1-->6) galactoside, a new flavonol glycoside, quercetin 3-glucosyl(1-->4)galactoside, and 1,6,8-trihydroxy-3-methyl anthraquinone (emodin) have been characterized from leaves of Rumex chalepensis. The structures were established on the basis of Rf values, acid hydrolysis to aglycone and sugar and UV, EI and FAB-mass spectra, 1H NMR, 13C DEPT NMR, NOE difference measurement, 1H-H COSY and 1H-13C COSY spectral data.

Anthraquinones↗
PubMed1995

Generation and characterization of an antiserum reactive with a proteolytic processing site within rat procorticotrophin-releasing hormone.

In this paper we report the generation of an antibody specific for the cleavage site within procorticotrophin-releasing hormone (proCRH) at the N-terminus proCRH/CRH (1-41) junction. Using radioimmunoassay techniques were show that the antibody generated (781) cross-reacts specifically with the proCRH (137-150) Tyr fragment, corresponding to the cleavage site within the full length precursor molecule. The anti-cleavage site antibody does not crossreact with the endoproteolytic products originated from the CRH precursor molecule, i.e. CRH (1-41) or proCRH (125-151) or with any of the CRH-immunoreactive fragments tested i.e. CRH (36-41), CRH (1-20) and CRH (30-41). It also shows no cross-reactivity with CRH-related substances from other species, i.e. urotensin I (fish) and sauvagine (frog). The cleavage site antibody (781), recognizes the full length proCRH molecule in Western blotting and in liquid phase radioimmunoassay from transfected CHO-K1 cells expressing the full length pre-proCRH cDNA. Using immunofluorescence and immunoprecipitation techniques followed by SDS-PAGE and autoradiography, we confirm the presence of the intact CRH precursor molecule within the nucleus and the cytoplasm of stably transfected CHO-K1 cells expressing immunoreactive proCRH. The immunofluorescence studies using primary cultures of hypothalamic neurons, show that immunoreactive (IR) proCRH is localized within the perinuclear region and was also seen along the neuronal processes where it accumulates at their tips. Our results, therefore, show that this antibody will be an invaluable tool in the study of intracellular trafficking in relation to the endoproteolytic processing of the CRH precursor molecule.

Amino Acid Sequence↗
PubMed1995

Vitamin D deficiency rickets in breast-fed infants presenting with hypocalcaemic seizures.

At the Aga Khan Hospital (AKUH), 65 infants presented with hypocalcaemic seizures, subsequently found to have rickets. Forty-six infants less than 6 months were totally or predominantly breast fed. In a subgroup of 15 mothers and their infants, we found very low plasma levels of 25(OH) vitamin D of < 5 micrograms/l and 7.5 +/- 3.3 micrograms/l, respectively. Neither mothers nor infants received vitamin D supplementation. Maternal vitamin D deficiency and non-supplementation in the infants were the likely causes of rickets in our patients. Prophylactic vitamin D 400 i.u. administered to infants up to 2 years and 800 i.u. to women in pregnancy and during lactation is recommended to prevent vitamin D deficiency.

Breast Feeding↗