Biomedical subjects

A Molla

Publications and source records attributed to A Molla.

At least 55 records · Page 3Linked to original sources

PubMed1994

Cardiovascular risk factors in school children from low middle income families in Karachi, Pakistan.

Serum levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C) and triglycerides (TG) were determined on 239 school children aged 5-19 years belonging to lower middle class families. The mean TC, LDL-C, HDL-C and TG ranged from 3.70-4.37 mmol/L, 2.17-2.70 mmol/L, 0.94-1.14 mmol/L, 1.07-1.26 mmol/L respectively. In general, girls had higher TC, LDL-C and HDL-C levels. There was no significant difference in the TG levels between boys and girls. Thirty-three percent of the girls and 22% of the boys had TC level > or = 4.4 mmol/L, the level at which dietary intervention is recommended for children. Fifty-three percent of the girls and 37% of the boys had TG levels > or = than the 90th percentile of the levels for children of similar age and sex in North America. The HDL-C levels were low with 37% of the girls and 44% of boys having values < or = the 10th percentile of levels for North American children. The mean daily intake of cholesterol ranged from 241 mg to 364 mg/day. Except for the 5-9 year olds, boys had a higher cholesterol intake than girls (P < 0.005). Twenty-two percent of the boys and 32% of the girls were overweight but weight status was significantly associated with elevated TC levels only in the boys (P < 0.05). Activity level was not significantly related to TC levels but girls who were active had significantly higher HDL-C levels than girls who were sedentary (P < 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1993

Studies on dicistronic polioviruses implicate viral proteinase 2Apro in RNA replication.

A dicistronic poliovirus W1-P1/E/P2,3-1 with the genotype [PV]5'NTR-P1-[EMCV]IRES-[PV]P2,3-3'NTR (Molla, Jang, Paul, Reuer, and Wimmer, 1992, Nature 356, 255) was used to investigate whether the viral proteinase 2Apro, whose primary function in proteolytic processing was erased through the insertion of an internal ribosomal entry site (IRES) element into the ORF of the polyprotein, had other function(s) in viral replication. Deletion of 2Apro from W1-P1/E/P2,3-1 rendered the corresponding transcripts unable to replicate whereas partial deletion of 2Apro or an exchange of Cys109 (an amino acid of the catalytic triad of the proteinase) to Ala reduced RNA replication. No cytopathic effects were observed after transfection with any of the three dicistronic constructs containing mutant 2A, and no virus was recovered after attempts to expand a possibly low yield of mutant virus. In contrast, insertion of the IRES of encephalomyocarditis virus (EMCV) into the ORF of the poliovirus polyprotein at the cleavage site between 2Apro and 2B yielded the novel dicistronic virus W1-P1,2A/E/2BC,P3-1 with the genotype [PV]5'NTR-P1-2A-[EMCV]IRES-[PV]2BC-P3-3'NTR, expressing a small plaque phenotype. These results indicate that neither the intact P2 polypeptide nor the cleavage fragment 2AB of P2 is required for viral proliferation. On the other hand, 2Apro appears to be an essential component in RNA replication as no viral RNA synthesis can be observed by reverse transcription/PCR in cells transfected with dicistronic RNA lacking this viral polypeptide.

Base Sequence↗

PubMed1993

Effects of temperature and lipophilic agents on poliovirus formation and RNA synthesis in a cell-free system.

The translation and primary processing events of poliovirus polyproteins in HeLa cell extracts were more efficient at 34 degrees C than at 30 or 36 degrees C. The cleavage products of P2 such as 2Apro, 2BC, and 2C appeared early in the reaction before the appearance of the cleavage products of P1 and of 3CDpro, an observation suggesting that P2 was cleaved in cis by 3CDpro. Proteolytic processing of the capsid precursor P1 into VP0, VP1, and VP3 was also more efficient at 34 degrees C than at either 30 or 32 degrees C. Surprisingly, processing of 3CDpro to 3Cpro and 3Dpol was almost completely inhibited at 36 degrees C. The synthesis of virus in the cell extract was greatly enhanced at 34 degrees C over that at 30 or 32 degrees C, whereas incubation at 36 degrees C yielded very little virus. Cerulenin, an inhibitor of lipid synthesis, did not appear to affect virus-specific translation or protein processing, but it almost completely inhibited viral synthesis in vitro. Oleic acid drastically inhibited in vitro translation at 100 microM and in vitro poliovirus synthesis at 25 microM. Addition of HeLa cell smooth membranes partially restored translation but not virus formation. Our observations suggest that in vitro translation, proteolytic processing, and virus formation require intact membranes. Analysis of the in vitro translation products revealed that viral RNA polymerase activity increased linearly during incubation of the translation mixture. RNA polymerase in the crude mixture was inhibited by oleic acid but not by cerulenin. Surprisingly, oleic acid had no direct effect on oligo(U)-primed, poly(A)-dependent poly(U) synthesis catalyzed by purified 3Dpol.

Cell-Free System↗

PubMed1993

Inhibition of proteolytic activity of poliovirus and rhinovirus 2A proteinases by elastase-specific inhibitors.

A polyprotein cleavage assay has been developed to assay the proteolytic activities in vitro of the 2A proteinases encoded by poliovirus and human rhinovirus 14, which are representative members of the Enterovirus and Rhinovirus genera of picornaviruses, respectively. The elastase-specific substrate-based inhibitors elastatinal and methoxysuccinyl-Ala-Ala-Pro-Val-chloromethylketone (MPCMK) inhibited both 2A proteinases in vitro. The electrophoretic mobilities of both 2A proteinases were reduced upon incubation with elastatinal, whereas the mobility of a Cys-109-->Ala poliovirus 2Apro mutant was unchanged, an observation suggesting that this inhibitor may have formed a covalent bond with the active-site Cys-109 nucleophile. Iodoacetamide, calpain inhibitor 1, and antipain inhibited poliovirus 2Apro. MPCMK caused a reduction in the yields of the enteroviruses poliovirus type 1 and coxsackievirus A21 and of human rhinovirus 2 in infected HeLa cells but did not affect the growth of encephalomyocarditis virus, a picornavirus of the Cardiovirus genus. MPCMK abrogated the shutoff of host cell protein synthesis that is induced by enterovirus and rhinovirus infection and reduced the synthesis of virus-encoded polypeptides in infected cells. These results indicate that the determinants of substrate recognition by 2A proteinases resemble those of pancreatic and leukocyte elastases. These results may be relevant to the development of broad-range chemotherapeutic agents against entero- and rhinoviruses.

Amino Acid Chloromethyl Ketones↗

PubMed1993

Vitamin A status of children in the urban slums of Karachi, Pakistan, assessed by clinical, dietary, and biochemical methods.

We assessed the vitamin A status of 532 children with an age range of 6-60 months who were living in slum areas of Karachi, Pakistan, using three methodologies: clinical eye examination, dietary vitamin A intake, and serum retinol level. No definite clinical signs of xerophthalmia were observed in any of these children. The mean +/- SD vitamin A intake estimated from a food frequency questionnaire for the group with inadequate (low and deficient) serum retinol levels (< 20 micrograms/dl) was 362 +/- 332 retinol equivalents (RE) compared with 431 +/- 332) RE in the group with adequate serum levels (P < 0.005). Deficient serum retinol levels (< 10 micrograms/dl) were present in 12 children (2%); two of these had a healed corneal scar. Low serum retinol levels (10-19 micrograms/dl) were present in 46%, while 51% children had adequate levels (> or = 20 micrograms/dl). The mean +/- SD serum retinol level for the inadequate (< 20 micrograms/dl) and adequate groups were 15.3 +/- 2.8 and 26.6 +/- 6.7 micrograms/dl, respectively. These results suggest that a significant number of children in these communities have low vitamin A levels and thus may constitute an at risk group. These results also suggest that the dietary intake method may be a simple and inexpensive screening tool for assessment of vitamin A status in communities.

Anthropometry↗

PubMed1993

Is anemia an accurate predictor of vitamin A status in Pakistani children?

Serum retinol and hemoglobin levels were determined in 532 children aged 6-60 months living in urban slums of Karachi, Pakistan. Overall 67% (358 of 532) of children had hemoglobin levels of less than 11 g/dl, the World Health Organization definition of anemia for this age group. Estimations for red blood cell indices (hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and red blood cell count) were done on a sample of 391 children to classify anemia morphologically. A similar percentage (69.8% [273 of 391 children]) of anemia was found in this group. The anemia was predominantly microcytic and hypochromic. Normocytic normochromic anemia was present in only 16.5%. Serum retinol levels were significantly correlated with hemoglobin (P < 0.002), hematocrit (P < 0.01), and red blood cell (P < 0.001) levels. However, anemia was found to be a poor predictor (positive predictive value [PPV] = 2.5%) for the presence of vitamin A deficiency (retinol < 10 micrograms/dl). The PPV increased to 54% if 20 micrograms/dl, which is an indicator of marginal vitamin A status, was used as the cutoff point. The sensitivity of the hemoglobin test was found to be 75% in correctly identifying vitamin A deficiency when retinol levels of 10 micrograms/dl and 20 micrograms/dl were both used as the cutoff points for deficiency. The specificity for the hemoglobin test varied from 33% to 40% when levels of 10 micrograms/dl and 20 micrograms/dl were used as the cutoff points for vitamin A deficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗

PubMed1993

The impact of nutritional counselling on serum lipids, dietary and physical activity patterns of school children.

Eighty-eight school children and their parents who had been counselled regarding appropriate dietary and activity patterns aimed at reducing serum cholesterol were followed-up 21 months later to determine changes in dietary and activity patterns and in serum lipid levels. The decline in serum total cholesterol ranged from 8 to 14% in the different age and sex groups (P < 0.05 to P < 0.001). Serum triglycerides did not change significantly. Cholesterol intake decreased 36% and 54% in 10-14 year old boys and girls respectively (P > 0.001). The activity level increased significantly in both the 5-9 year and 10-14 year olds (P < 0.05 to P < 0.005). These results show that nutrition education can bring about a change in dietary and activity patterns, resulting in a decline in serum cholesterol levels.

Adolescent↗

PubMed1993

Does red blood cell distribution width (RDW) improve evaluation of microcytic anaemias?

The red cell distribution width (RDW) is an index of the variation in red cells size (anisocytosis). A study was conducted to examine the validity of using RDW in improving classification of microcytic anaemias. A total of 300 blood samples collected from a patient population aged 3 months to 55 years who were referred for haemoglobin electrophoresis were examined at the Aga Khan University Hospital (AKUH). On complete blood count, initially 200 patients (66.6%) were found to have hypochromic microcytic anaemia. Following haemoglobin electrophoresis 41% (82/200) patients were diagnosed to have thalassemia minor and 59% (118/200) had hypochromic microcytic anaemia with either a normal haemoglobin pattern or an abnormal haemoglobin. The mean (+/- SD) RDW estimated in 250 apparently healthy Pakistani population was 14 (+/- 1.5%). Elevated RDW of 23% was present in 94% (110/118) of the patients with hypochromic microcytic anaemia due to other causes, whereas 48% (39/82) of the patients with thalassemia minor had elevated RDW of 16%. Also, of the 82 thalassemia minor, 28 patients had normal haemoglobin level, of which 6 had elevated RDW and of the 54 with low haemoglobin level, 35 had elevated RDW. RDW was normal in 41 patients with thalassemia minor trait. Our results suggest that RDW alone cannot be used as a reliable indicator to distinguish between thalassemia minor and other causes of microcytosis.

Adolescent↗

PubMed1993

Malabsorption of nutrients in children with diarrhoea due to unknown aetiologies.

Intake and coefficient of absorption of nutrients were measured in 72 children during acute diarrhoea and 2 weeks after recovery. No diarrhoeal pathogens could be identified in 18 (25%) children (group I). Aetiology of diarrhoea was identified in rest of the 54 children (group II). Absorption of calorie, fat and carbohydrate during the recovery stage were similar in all 72 children. In group I, absorption of nutrients improved from acute stage to recovery stage as follows: fat from 62 to 85%, calories from 68 to 86% and carbohydrate from 81 to 91%. Absorption of nitrogen during the acute stage was significantly lower (P < 0.01) in group I (mean +/- SD: 2% +/- 56) than in group II (mean +/- SD: 49% +/- 28). The anion gap in the stool of group I children (32) was similar to those with shigellae (37) and rotavirus (38). This could partially be explained by the possible loss of anionic proteins, fatty acids and/or lactic acids in the diarrhoeal stool. Results suggest that the diarrhoea due to unknown aetiology is possibly of the invasive type. Further investigation is necessary to define the mechanism of nitrogen loss in acute diarrhoea of unknown aetiology.

Acute Disease↗

PubMed1993

In vitro synthesis of poliovirus.

A HeLa cell-free extract has been prepared that efficiently uses full-length poliovirus-specific RNA, transcribed from plasmids with phage T7 RNA polymerase, or poliovirion RNA, for viral protein synthesis in vitro. Extensive proteolytic processing of the polyprotein in the extract produced viral enzymes that led to de novo viral RNA synthesis, and to the formation of infectious particles, as assayed on HeLa cell monolayers. The titre of plaque-forming units (p.f.u.) in the cell-free extract could be increased 70-fold when nucleoside triphosphates were added to the incubation mixture. Formation of infectious material was completely abolished if guanidine hydrochloride, an inhibitor of poliovirus RNA synthesis, but not of viral protein synthesis, was added; it was restored when the template used in the incubation was the RNA of a guanidine-resistant poliovirus mutant. Infectivity was completely inhibited by type-specific neutralizing antisera to poliovirus, and plaques were not formed if the HeLa cell monolayers were first treated with monoclonal antibodies to the poliovirus receptor. These results suggest de novo synthesis of poliovirus in a cell-free extract.

Capsid↗

PubMed1993

Suggested reference ranges in clinical chemistry for apparently healthy males and females of Pakistan.

Seven hundred and eighty six apparently healthy males (418) and females (368) aged 0-69 years were randomly selected for estimation of reference ranges of 24 serum analytes at the clinical chemistry laboratory of The Aga Khan University Hospital (AKUH). Of the total study samples, 56% (439/786) were in the paediatric age group (0-14 years) and 44% (347/786) in the adult (15 > or = 60 years) group. Beckman Astra Ideal Autoanalyzer was used for all the estimations. Mean and standard deviations (SD) were calculated for each of the age groups. Reference ranges were calculated following standard methods of the International Federation of Clinical Chemistry (IFCC) and International Committee for Standardization in Haematology (ICSH).

Adolescent↗

PubMed1992

Cardioviral internal ribosomal entry site is functional in a genetically engineered dicistronic poliovirus.

High mutation rates have driven RNA viruses to shorten their genomes to the minimum possible size. Mammalian (+)-strand RNA viruses and retroviruses have responded by reducing the number of cis-acting regulatory elements, a constraint that has led to the emergence of the polyprotein. Poliovirus is a (+)-stranded picornavirus whose polyprotein, encoded by an open reading frame spanning most of the viral RNA, is processed by virus-encoded proteinases. Despite their genetic austerity, picornaviruses have retained long 5' untranslated regions, which harbour cis-acting elements that promote initiation of translation independently of the uncapped 5' end of the viral messenger RNA. These elements are termed 'internal ribosomal entry sites' and are formed from highly structured RNA segments of at least 400 nucleotides. How these elements function is not known, but special RNA-binding proteins may be involved. The ribosome or its 40S subunit probably binds at or near a YnXmAUG motif (where Y is a pyrimidine and X is a purine) at the 3' border of the internal ribosomal entry site, which either provides the initiating codon or enables the ribosome to translocate to one downstream (E.W. et al., submitted). Initiation from most eukaryotic messenger RNAs usually occurs by ribosomal recognition of the 5' and subsequent scanning to the AUG codon. Here we describe a genetic strategy for the dissection of polyproteins which proves that an internal ribosomal entry site element can initiate translation independently of the 5' end.

Binding Sites↗

PubMed1992

Lack of transcription and expression of the alpha IIb integrin in human early haematopoietic stem cells.

The glycoprotein IIb, the alpha subunit of the platelet integrin GPIIb-IIIa, is a marker of megakaryocyte, but the stage of its expression during haematopoiesis remains controversial. We have examined the expression of GPIIb protein and alpha IIb mRNA in early human normal stem cells. We have purified stem cell expressing the CD34 surface marker (CD34+ fraction) and selected among this population quiescent cells (CD34+ MF(R) fraction). We have failed to detect GPIIb protein and alpha IIb mRNA in the pluripotential (CD34+ MF(R)) cells, even with polymerase chain amplification. Therefore alpha IIb transcription and GPIIb protein expression seemed to follow the commitment of the pluripotential cell in the megakaryocyte lineage.

Antigens, CD↗

PubMed1992

Mutational analysis of the proposed FG loop of poliovirus proteinase 3C identifies amino acids that are necessary for 3CD cleavage and might be determinants of a function distinct from proteolytic activity.

Mutations were introduced into a cDNA clone of poliovirus resulting in single-amino-acid substitutions within the region of the proposed FG loop of proteinase 3C. RNAs were made by in vitro transcription with T7 RNA polymerase and used to transfect HeLa cells. Virus viability was assessed as indicated by cell lysis. In parallel, RNAs were translated in vitro by using a HeLa cell lysate, and the patterns of the processed poly-proteins were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Replacement of Lys-78, Arg-79, and Glu-81 had apparently no effect on virus viability and on proteolytic processing. In contrast, virus viability was abolished by mutation of Phe-83, Arg-84, Asp-85, Ile-86, and Arg-87. With respect to substitution of Phe-83, Asp-85, and Arg-87, these effects correlated with impaired processing of the 3CD cleavage site, separating 3C and 3D, and, to a lesser extent, of the P1 precursor. Replacement of Arg-84 and Ile-86, on the other hand, did not alter the processing pattern. Thus, the lethal effects in these mutant genomes may not have been caused by impaired processing. A special case was the mutant of Lys-82-Gln. Virus recovered from cells transfected with RNA carrying this mutation always contained an A-to-G transition which resulted in the replacement of glutamine for arginine. Our data suggest that residues in the proposed FG loop of proteinase 3C influence 3CD cleavage and that they are determinants of a function unrelated to proteolytic processing.

3C Viral Proteases↗

PubMed1992

Prevalence of iron deficiency anaemia in children of the urban slums of Karachi.

A preliminary baseline survey was conducted to estimate the prevalence of anaemia in a group of 391 children aged 6-60 months, randomly selected from three urban slums of Karachi. Haemoglobin and the red cell indices including haematocrit, MCV, MCH, MCHC, RBC and red cell distribution width (RDW) were estimated for each of the selected children. Ferritin estimation was done on 354 (91%) children to assess the iron storage status. According to WHO criteria, the accepted cut-off point for anaemia screening in children is set at 11 gm/dl, 70 fl and 20 pg for haemoglobin, MCV and MCH respectively. Following these criteria, 118 (30%) children were classified as normals (Hg = greater than 11 gm/dl) and 273 (70%) as anaemic (Hg = less than 11 gm/dl). Of the 354 ferritin estimations, 225 (64%) children had ferritin levels lower than normal (less than 11 ng/ml) and 128 (36%) had ferritin levels within normal limit (11-120 ng/ml). From this group, a total of 61% (214/354) children were classified as microcytic hypochromic (MIH) and 11% (39/354) of which had normal ferritin levels suggesting the presence of thalassemia minor trait. The overall results obtained indicate that iron deficiency anaemia is highly prevalent among these children.

Anemia, Hypochromic↗

PubMed1991

Cell-free, de novo synthesis of poliovirus.

Cell-free translation of poliovirus RNA in an extract of uninfected human (HeLa) cells yielded viral proteins through proteolysis of the polyprotein. In the extract, newly synthesized proteins catalyzed poliovirus-specific RNA synthesis, and formed infectious poliovirus de novo. Newly formed virions were neutralized by type-specific antiserum, and infection of human cells with them was prevented by poliovirus receptor-specific antibodies. Poliovirus synthesis was increased nearly 70-fold when nucleoside triphosphates were added, but it was abolished in the presence of inhibitors of translation or viral genome replication. The ability to conduct cell-free synthesis of poliovirus will aid in the study of picornavirus proliferation and in the search for the control of picornaviral disease.

Base Sequence↗

PubMed1991

Activation of ras oncogenes and expression of tumor-specific transplantation antigens in methylcholanthrene-induced murine fibrosarcomas.

The DNA of 22 fibrosarcomas, newly induced in BALB/c mice by subcutaneous doses of 3-methylcholanthrene (3-MCA), was tested in NIH 3T3 transformation assay. Activation of K-ras and N-ras was found in 7 and 3 cases respectively. No H-ras activation was detected. Polymerase chain reaction and oligonucleotide hybridization performed on the DNA of the 22 sarcomas revealed 5 cases of K-ras mutation at codon 12, 3 at codon 13 and 1 at both codons. One case of K13 mutation was not detectable by transfection. Three cases of mutation at codon 61 of N-ras were also found, one of which was simultaneous with a K12 mutation. Tumor-specific transplantation antigens (TSTA) were assessed in the 22 original tumors. Altogether 16 sarcomas were immunogenic, with the highest frequency of TSTA+ tumors (10/11 and 5/6) in the groups given 1.0 and 0.1 mg of 3-MCA respectively, the lowest (1/5) in that with 0.01 mg of carcinogen; ras mutations occurred in the DNAs of 11 out of the 16 TSTA+ sarcomas, but none of the DNAs of the 6 TSTA- tumors showed ras mutation. The results suggest that 3-MCA-induced transformation of subcutaneous fibroblasts can involve mutations in codons 12, 13 or 61 of K- and N- but not H-ras gene and that such mutation is accompanied by the expression of TSTA.

Animals↗

PubMed1991

Factors associated with elevated serum cholesterol levels in well-to-do Pakistani schoolchildren.

Cholesterol (CH) and triglyceride (TG) levels were determined in blood drawn after an overnight fast from 388 school children aged 5-19 years from private schools in Karachi. The mean CH levels ranged from 4.4 to 4.6 mmol l-1 (170.1 to 177.9 mg dl-1) for boys and 4.4 to 4.8 mmol l-1 (170.1 to 185.6 mg dl-1) for girls. The range of TG levels was 1.0 to 1.2 mmol l-1 (88.6 to 106.3 mg dl-1) and 0.9 to 1.1 mmol l-1 (79.7 to 97.4 mg dl-1) for boys and girls respectively. Sixty-two per cent of the girls and 54% of the boys had cholesterol values greater than or equal to 4.4 mmol l-1 (170 mg dl-1), a level at which dietary intervention is recommended for children. Thirty-two per cent of all the children had triglyceride levels above the 90th percentile of the levels for similar age groups in North America. The mean cholesterol intake was 469 mg/day for girls and 518 mg/day for boys. Overweight and inactivity were associated with raised serum cholesterol levels. Forty per cent of the girls and 25% of the boys reported a strong family history of hypercholesterolaemia and/or heart disease. The results show that the prevalence of hypercholesterolaemia is high in well-to-do Pakistani school children and factors which can be modified to lower serum cholesterol levels are identified.

Adolescent↗