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Biomedical subjects

N Akhtar

Publications and source records attributed to N Akhtar.

At least 19 recordsLinked to original sources
PubMed1996

Purification and characterization of two isoenzymes of DL-glycerol-3-phosphatase from Saccharomyces cerevisiae. Identification of the corresponding GPP1 and GPP2 genes and evidence for osmotic regulation of Gpp2p expression by the osmosensing mitogen-activated protein kinase signal transduction pathway.

The existence of specific dl-glycerol-3-phosphatase (EC 3.1.3.21) activity in extracts of Saccharomyces cerevisiae was confirmed by examining strains lacking nonspecific acid and alkaline phosphatase activities. During purification of the glycerol-3-phosphatase, two isozymes having very similar molecular weights were isolated by gel filtration and anion exchange chromatography. By microsequencing of trypsin-generated peptides the corresponding genes were identified as previously sequenced open reading frames of unknown function. The two genes, GPP1 (YIL053W) and GPP2 (YER062C) encode proteins that show 95% amino acid identity and have molecular masses of 30.4 and 27.8 kDa, respectively. The intracellular concentration of Gpp2p increases in cells subjected to osmotic stress, while the production of Gpp1p is unaffected by changes of external osmolarity. Both isoforms have a high specificity for dl-glycerol-3-phosphate, pH optima at 6.5, and KmG3P in the range of 3-4 mM. The osmotic induction of Gpp2p is blocked in cells that are defective in the HOG-mitogen-activated protein kinase pathway, indicating that GPP2 is a target gene for this osmosensing signal transduction pathway. Together with DOG1 and DOG2, encoding two highly homologous enzymes that dephosphorylate 2-deoxyglucose-6-phosphate, GPP1 and GPP2 constitute a new family of genes for low molecular weight phosphatases.

Amino Acid Sequence↗
PubMed1996

PCR diagnosis of viral pneumonitis from fixed-lung tissue in children.

Viral infection in children commonly causes acute lung disease leading to respiratory decompensation requiring intensive supportive therapy. Definitive diagnosis of the causative virus may be difficult, relying on serologic data since viral cultures are frequently negative; lung biopsy may be necessary to increase the diagnostic yield. The objective of this study was to develop a rapid and sensitive diagnostic method using the polymerase chain reaction (PCR). Analyzing Formalin-fixed lung tissue from autopsies of 32 patients with pneumonitis in whom cultures, serology, and histopathology results were blinded to the investigators, and 10 negative control samples, PCR was performed for cytomegalovirus, adenovirus, enteroviruses, herpes simplex virus, and Epstein-Barr virus. Among the 32 affected specimens, 7 were culture-positive for a specific virus in the lung; 6/7 of these were PCR-positive for the identical virus. In the culture-positive specimen not PCR amplified, influenza B was the cultured agent, but this virus was not evaluated by PCR. In the remaining 25 samples which were culture-negative, 11 were PCR-positive. All 10 negative controls were negative by PCR. Three specimens with CMV inclusions but culture-negative were also negative by PCR. We conclude that PCR is sensitive and accurate in the evaluation of lung tissue for viral pneumonitis.

Adolescent↗
PubMed1996

Eighteen-month-old children learn words in non-ostensive contexts.

Previous studies have demonstrated that children aged 2;0 can learn new words in a variety of non-ostensive contexts. The current two studies were aimed at seeing if this was also true of children just beginning to learn words at 1;6. In the first study an adult interacted with 48 children. She used a nonce word to announce her intention to find an object ('Let's find the gazzer'), picked up and rejected an object with obvious disappointment, and then gleefully found the target object (using no language). Children learned the new word as well in this condition as in a condition in which the adult found the object immediately. In the second study the adult first played several rounds of a finding game with each of 60 children, in which it was first established that one of several novel objects was always in a very distinctive hiding place (a toy barn). The adult then used a nonce word to announce her intention to find an object ('Let's find the toma') and then proceeded to the barn. In the key condition the barn was mysteriously 'locked'; the child thus never saw the target object after the nonce word was introduced. Children learned the new word as well in this condition as in a condition in which the adult found the object immediately. The results of these two studies suggest that from very early in language acquisition children learn words not through passive, associative processes, but rather through active attempts to understand adult behaviour in a variety of action and discourse contexts.

Adult↗
PubMed1996

Down's syndrome screening using free beta hCG: instability can significantly increase the Down's risk estimate.

The stability of free beta hCG (human chorionic gonadotrophin) was assessed using a dual alpha-fetoprotein and free beta hCG assay. A significant increase in free beta hCG concentration was observed in heparinized samples left unseparated for 24 h or more, the mean increase in 21 samples being 10.2% after 24 h (P = < 0.001), increasing to 45.7% after 96 h. Similar results were also obtained in clotted samples. The effect of the increase in free beta hCG on the Down's risk estimate was calculated to assess the impact of delayed sample transport and separation. The Down's risk increased in all samples with increasing separation time, but this was most significant in two samples where, using a cut off of one in 250, the risk classification changed from low risk to high risk. These results suggest that delayed sample separation can have a significant effect on screening programmes using free beta hCG, particularly with respect to those patients whose risk classification is changed.

Blood Specimen Collection↗
PubMed1996

CT and MR evaluation of a wooden foreign body in an in vitro model of the orbit.

We made an in vitro model of a wooden foreign body using both fresh and dry pine wood in both fat and soft-tissue background mediums. Air/wood/background medium interfaces were studied with MR and CT to determine which method provided the best image contrast for detecting a wooden foreign body. CT was demonstrated to be superior to MR in the evaluation of the orbit in the in vitro model.

Animals↗
PubMed1995

Nutritional evaluation of desi and kabuli chickpeas and their products commonly consumed in Pakistan.

Physicochemical and nutritional quality of five improved cultivars of desi and kabuli chickpeas and their products were studied. The kabuli chickpea had larger seed (26 g/100 seeds) than desi type (21 g/100 seeds). The hydration capacity per seed of desi (0.16 g) was lower than kabuli type (0.26 g). A positive correlation (r = 0.87) between seed weight and hydration capacity was observed. The mean cooking time of dry desi vs kabuli seed (124.5 vs 113.8 min) was reduced to 37.5 vs 32.8 min and to 28.8 vs 22.5 min when soaked overnight in water and in 0.5% solution of sodium bicarbonate respectively. The mean value of protein (25.4 vs 24.4%), fat (3.7 vs 5.1%), carbohydrate (47.4 vs 55%), crude fibre (11.2 vs 3.9%), ash (3.2 vs 2.8%) and caloric value (327 vs 365 kcal/100 g) were for desi vs kabuli chickpeas respectively. There was no difference in the essential amino acid contents and in chemical scores of desi (65) and kabuli (67) chickpeas. The order of limiting amino acid was methionine+cystine, threonine and valine in both types. The chickpeas products contained 8.9-21.1% protein (N x 6.25), 3.1-21.8% fat, 53.4-75.9% carbohydrate, 1.6-11.1% crude fibre, 1.2-5.9% ash, 226-360mg Ca, 126-315 mg P, 3.8-8.2 mg Fe, 1.8-5.4 mg Zn, 1.5-5.4 mg Mn, 0.6-1.1 mg Cu and 370-490 kcal per 100 g. All chickpea products provided 7-23%, 7-40% and 52-78% of the total calories from protein, fat and carbohydrates respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1994

Extradural causes of myelopathy.

Myelopathy, the rapid or insidious onset of motor and sensory abnormalities referable to the spinal cord, occurs as a result of a variety of causes that may be classified on the basis of their location of origin (intramedullary, intradural-extramedullary, and extradural). The first goal of imaging is to appropriately assign the observed abnormality to its location of origin and, therefore, into the correct diagnostic list. This article focuses on the plain film, computed tomography, and magnetic resonance demonstration of extradural causes of myelopathy.

Bacterial Infections↗
PubMed1994

Interaction of 1,9-dimethylmethylene blue with glycosaminoglycans.

The specific binding of 1,9-dimethylmethylene blue (DMB) with glycosaminoglycans (GAGs) was studied including molecular analysis of the GAG species using mass spectrometry. The dye solution was unstable under any storage conditions. Inorganic analysis showed that the purity of the dye was variable from different sources. False negative results could be obtained when using impure dye. Binding of the dye with GAG resulted in the formation of a complex with an absorption maximum at 525 nm. The absorbance of the complex was linearly correlated with GAG concentration up to 150 mg/L. The specific molar extinction coefficients of individual GAG molecules were calculated in relation to the molar absorbance of the GAG-dye complex and the carbon and nitrogen contents of the GAGs. The results indicated that binding of dye occurred at both the ionized sulphate and carboxyl groups on the GAG molecules. Improvements of the DMB-binding method for the measurement of GAGs are suggested.

Drug Storage↗
PubMed1993

Possible case of procainamide-induced intrahepatic cholestatic jaundice.

OBJECTIVE: To describe a possible case of procainamide-induced intrahepatic cholestatic jaundice that was recognized six weeks after the initiation of procainamide therapy and to summarize the five previously reported cases. CASE SUMMARY: A 77-year-old woman with a history of hypertension, insulin-dependent diabetes mellitus, temporal arteritis, and Wolff-Parkinson-White syndrome who had taken procainamide for six weeks presented to the hospital with disorientation and acute renal and hepatic dysfunction. In addition to disorientation, scleral icterus, and diffuse maculopapular rash, her physical examination was generally normal. There was no evidence of fever, nausea, vomiting, lymphadenopathy, or eosinophilia. Her liver enzyme concentrations increased significantly from baseline (beginning of procainamide therapy). Her N-acetylprocainamide (NAPA) concentration was elevated to 52 mg/L upon admission. Procainamide was discontinued and her NAPA concentration returned to within normal limits in two days. Diagnostic tests were performed to rule out active hepatitis, vasculitis, and liver malignancies. After procainamide was discontinued and prednisone treatment was started, she became more oriented and her liver enzyme concentrations slowly improved. DISCUSSION: Only five cases of procainamide-induced liver abnormalities have been previously reported; these included granulomatous hepatitis and intrahepatic cholestasis. The mechanism for liver dysfunction is not known; however, it is proposed to be a delayed hypersensitivity reaction. Clinical hallmarks of hypersensitivity include fever, eosinophilia, rash, and lymphadenopathy; nausea and vomiting also may be present. Of the five reported cases, all experienced fever and only one experienced pruritus. No patients had eosinophilia or lymphadenopathy. Because of the temporal increase in liver enzyme concentrations after six weeks of procainamide therapy, we believe that this case represents another possible procainamide-induced hypersensitivity reaction. CONCLUSIONS: Procainamide-induced liver dysfunction can occur from one day to six weeks after initiation of the drug and may subside one day to several weeks after discontinuation of therapy. Symptoms may include nausea, vomiting, rash, and fever. Liver enzyme concentrations are abnormal. It is important to recognize the possibility of such a reaction early so that procainamide therapy can be discontinued promptly to avoid further liver damage.

Aged↗
PubMed1992

Restriction endonuclease analysis and ribotyping differentiate genital and nongenital strains of Bacteroides ureolyticus.

Thirty-three clinical isolates from male nongonococcal urethritis and 28 isolates from soft tissue infections and ulcers were identified as Bacteroides ureolyticus by conventional bacteriological tests and were compared with five reference strains of the species. Whole-cell proteins from these clinical isolates and the reference strains were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The majority of the strains from the two sources could be divided into five different groups, named phenons I to V; phenons I to IV have been described previously by others, while phenon V has been described recently by us. Digestion of chromosomal DNA from 16 of the clinical isolates (including strains representative of each of the five SDS-PAGE phenons) and the five reference strains was attempted with restriction endonucleases EcoRI, PstI, SmaI, and HindIII. After electrophoresis in agarose gels, good digestion was observed with HindIII only, and 12 different banding patterns (restriction endonuclease analysis [REA] profiles) were obtained for the 19 strains digested; one nongonococcal urethritis isolate and one reference strain did not show any digestion. From the agarose gels, HindIII-digested fragments of DNA were transferred to nylon membranes by use of vacuum blotting and subjected to hybridization with 32P-labelled 16S-23S rRNA from Escherichia coli. The resultant pattern of bands (ribotypes), which depends on the restriction fragment length polymorphisms in the rRNA genes, was used as a measure of genomic variation within the species. In total, 13 different ribotypes were obtained for the 19 strains. For some strains, good correlation was achieved among the SDS-PAGE phenons, REA profiles, and ribotypes. However, for others, REA analysis and ribotyping were able to discriminate between strains which shared the same SDS-PAGE phenon. Interestingly, these two techniques of DNA characterization were able to differentiate between isolates from the genital tract and those associated with soft tissue infections and ulcers.

Bacterial Proteins↗
PubMed1991

Directive interactions and early vocabulary development: the role of joint attentional focus.

Maternal directiveness, assessed by the mother's use of prescriptives, is correlated with slow vocabulary development. As prescriptives are most often used to redirect a child's attention to a different object or activity, it is hypothesized that attentional regulation underlies this negative relationship. In the present study, twelve mothers were videotaped interacting with their children aged 1;1, and 100 maternal utterances were coded for pragmatic intent. Prescriptives were coded as either changing (leading) or following the child's focus of attention. Only the frequency of mothers' follow-prescriptives correlated significantly with a productive vocabulary measure taken at 1;10. This correlation was high and positive, indicating that, given joint focus, directing a 13-month-old's behaviour can have beneficial effects on subsequent vocabulary development.

Attention↗
PubMed1991

The clinical relevance of plasma viscosity in Hodgkin's disease.

The erythrocyte sedimentation rate has previously been identified as an important prognostic factor in Hodgkin's disease. The plasma viscosity has replaced the ESR measurement in many laboratories, but doubts exist about its clinical relevance. In this study plasma viscosity at presentation/diagnosis was studied in 107 patients with Hodgkin's disease. A multivariate analysis of factors influencing prognosis and relapse-free survival identified plasma viscosity and number of disease sites as being highly significant. The risk of relapse increases initially with a rise in plasma viscosity, but after a value of about 2.0 mPa.s no further increase in risk is observed. When all of the prognostic factors are made available to the proportional hazards model, treatment modality and plasma viscosity are selected as the best set for predicting time to first relapse. This study demonstrates that measurement of plasma viscosity at presentation is an important prognostic factor in Hodgkin's disease, in terms of predicting outcome or risk of relapse.

Adult↗
PubMed1991

The nonreciprocating robot: effects on verbal discourse, social play, and social referencing at two years of age.

2-year-old children interacted with a robot in a large playroom while their mother sat quietly in the corner. Identical vocalizations from the robot had very different effects on 3 dimensions of the children's behavior when the vocalizations were embedded in reciprocating and nonreciprocating social structures. The reciprocating robot produced (1) more topic-maintaining verbal dialogue, (2) less physical and more linguistically mediated social play, and (3) gender-specific effects on the children's tendency to visually reference their mother during the play session. The data are discussed with reference to the frequently encountered assumption that reciprocal social structures have an impact on children's behavior when the quantity and other qualitative dimensions of social stimulation are held constant, and with reference to the children's attributions about the robot as a social partner.

Child, Preschool↗