PubMed Health⌕ Search

Biomedical subjects

R Ali

Publications and source records attributed to R Ali.

At least 127 records · Page 7Linked to original sources
PubMed1991

Antibodies against DNA-psoralen crosslink recognize unique conformation.

The DNA-psoralen crosslink induced precipitating antibodies in rabbits with a titer of 1:102,400 by direct binding ELISA. The antiserum showed considerable binding with Z-DNA and calf thymus DNA brominated under high salt concentration which has been shown to attain Z-/analogous conformation. Inhibition experiments substantiated the results of direct binding assay. However, the affinity purified IgG showed high degree of specificity for the immunogen and did not recognize nDNA, Z-DNA and brominated DNA as inhibitor. Poly(dG.dC).poly(dG.dC)-psoralen photoadduct was found to be inhibitory. These results indicate that the antibodies are probably recognizing the unique conformation at the site of psoralen crosslinking. The DNA-psoralen crosslink showed significant binding with SLE sera known to have high levels of anti-native DNA antibodies. Affinity purified SLE-IgG in a competition assay pointed out the autoantibody recognition of altered conformation of DNA-psoralen crosslink.

Animals↗
PubMed1991

HIV prevalence and risk behaviours for HIV transmission in South Australian prisons.

During the latter half of 1989, HIV prevalence in South Australian prisoners was 1.4%. The prevalence of HIV infection across the prison system did not change significantly during 1989 but there was clustering of HIV-infected prisoners in some prisons. Almost half the prisoners from all of the South Australian prisons agreed to participate in our studies, from which we estimate that about 42% of prisoners engage in risk behaviours at least once while incarcerated. Prisoners estimated that 36% of all prisoners inject drugs intravenously at some stage during their stay and that 12% engage in anal intercourse at least once. Interviews with former prisoners who had a history of intravenous drug use revealed that about half had injected themselves while in prison, 60% shared needles and most did not clean shared needles adequately. Most of these prisoners injected themselves once a month or less frequently. The conditions for spread of HIV within the prison system exist but at the current prevalence of infection, transmission can be expected to be infrequent. The opportunity exists now to improve and expand preventive measures.

Adult↗
PubMed1991

Bloody needles: the volumes of blood transferred in simulations of needlestick injuries and shared use of syringes for injection of intravenous drugs.

Residual HIV-infected blood in needles and syringes is a source of HIV infection. Using radiolabelled blood we have stimulated needlestick injuries and sharing of syringes by intravenous drug users and quantified the volumes of blood which could be transferred to recipients in these situations. Up to 0.75 microliters of blood was transferred in needlestick simulations, but there was a large variation. In simulations of needlesharing, seven to ten times more blood was transferred from the index user to the first sharer when 2 ml syringes were used compared with 1 ml syringes. Washing with water was not effective in removing 'infected' blood from a syringe.

HIV Infections↗
PubMed1991

Antigen binding diversity of affinity purified autoantibodies against DNA.

Naturally occurring autoantibodies against native DNA (nDNA) in SLE sera showed diverse antigen binding characteristics. The antibodies isolated by affinity chromatography using nDNA linked to Sepharose 4B exhibited specificity towards nDNA and showed strong reactivity with DNA-psoralen photoadduct by direct binding assay and competitive ELISA. The anti-DNA antibody belong to both IgG and IgM immunoglobulin classes and their ratio was 5:1. The possible significance of altered conformation of nDNA in the etiology of SLE has been discussed.

Antibodies, Antinuclear↗
PubMed1990

Generation of small mutation in large genomic fragments by homologous recombination: description of the technique and examples of its use.

We have developed a technique of homologous recombination in bacteria which allows the mutagenesis of large genomic fragments cloned in cosmids. The desired mutation is first introduced into a plasmid clone and is then transferred to the appropriate cosmid clone by the means of double antibiotic selection coupled with phenotypic selection. We describe three different types of construct made by this technique.

Cloning, Molecular↗
PubMed1990

Effects of an amino acid solution enriched with either branched chain amino acids or ornithine-alpha-ketoglutarate on the postoperative intracellular amino acid concentration of skeletal muscle.

Patients undergoing elective cholecystectomy provide a highly reproducible model of the effects of trauma on intermediary metabolism. Three parenteral nutrition regimens were given to groups of eight such patients. An isonitrogenous total parenteral nutrition, including a commercially available amino acid solution, an amino acid solution enriched with branched chain amino acids or one supplemented with ornithine-alpha-ketoglutarate, was given after operation. The intra cellular free amino acid concentrations of skeletal muscle were determined in tissue specimens obtained before operation and on the third postoperative day using a percutaneous needle biopsy technique. The mean (s.e.m.) decrease in the concentrations of free intracellular glutamine on the third postoperative day was less pronounced (P less than 0.05) in the ornithine-alpha-ketoglutarate group (18.8(7.5)per cent) than in the control group (39.4(5.1)per cent) or the branched chain amino acid group (45.3(6.1)per cent). In conclusion, in the immediate postoperative period total parenteral nutrition supplemented with ornithine-alpha-ketoglutarate countered the decline in the muscle free glutamine. No difference in this parameter was seen between the control group and the branched chain amino acid group.

Amino Acids↗
PubMed1990

A plant dye from Lawsonia inermis for protein staining after polyacrylamide gel electrophoresis.

A reddish-brown dye was isolated from the leaves of Lawsonia inermis by extraction with calcium hydroxide (pH 11-12). A 3.6% crude extract in ethanol/water, 1:1 v/v, was used for direct staining, without fixation, of bovine serum albumin, casein and human serum proteins, following polyacrylamide gel electrophoresis in cylindrical gels. After staining for 30 min the gels were destained for 1/2-2 h with 7% acetic acid at 60 degrees C. Protein staining with Amido Black 10B and Coomassie Brilliant Blue R-250, according to standard protocols, required destaining for 24 h and more to obtain a comparably cleared background. Staining with the plant dye and Coomassie Brilliant Blue had a similar overall staining sensitivity but some minor components of human serum showed different staining characteristics with each of the two dyes. Staining with the plant dye excels over standard staining by speed and simplicity.

Caseins↗
PubMed1990

Antibody recognition of common epitopes on Z-DNA and native DNA brominated under high salt.

Native calf thymus DNA brominated under high salt (4 M NaCl) adopt Z-/analogous conformation as indicated by UV absorption and difference spectra. The bromination of guanine (44%) was twice as effective as cytosine (22%) and induced thermal instability in the modified polymer. The changes are similar to those observed in Z-form of poly(dG.dC).poly(dG.dC). Antibodies were raised in rabbits against these conformationally altered nucleic acids. Both the polymers were highly immunogenic and produced high titer precipitating antibodies which were completely identical in double immunodiffusion. Immunoaffinity purified IgGs showed binding of common conformational epitopes on Z-DNA and brominated DNA. It is evident that on bromination in high salt, regions of native DNA attain Z-/analogous conformation along its strand.

Animals↗
PubMed1990

Naturally occurring anti-native DNA antibodies in SLE binding Z-DNA.

A high degree of specificity of circulating anti-DNA antibody for double stranded DNA in the sera of SLE patients was found, as compared to single stranded polymer. The antibody recognized brominated DNA, a polymer that appears to attain Z-conformation as indicated on the basis of UV absorption characteristics. The existence in native DNA of regions undergoing B----Z transition has been detected.

Antibody Specificity↗
PubMed1989

Reproductive health of adolescents in Bangladesh.

The health and social effects of pregnancy in married women 13-23 years of age were studied among a population of 175,000 in rural Bangladesh. Data collected by a structured questionnaire identified pregnant women who were followed twice during pregnancy and twice postpartum. Maternal mortality for the 13-17 age group was 5.8/1000 compared to 1.8/1000 for the 18-23 year olds. Major causes of death in the younger group were obstructed labor and toxemia. The neonatal death rate was 80/1000 for the younger group and 43/1000 for the older group. The major cause of death of infants born to the younger mothers was birth injury. In infants born to older mothers, it was tetanus. Perinatal death rate was 66.4/1000. All deliveries occurred at home, and 89% of births were attended by relatives, neighbors or an untrained birth attendant. Only 13% of the women had ever used contraceptives. Use varied from 2.9% at 16 years to 24.7% at 23 years. Suggestions are made for improving maternal and child health care in rural Bangladesh.

Adolescent↗
PubMed1989

Immunochemical reactivity of native and modified preparations of pig kidney diamine oxidase.

This paper describes the antigenicity of pig kidney diamine oxidase [EC 1.4.3.6] and the possible role of constituent amino acids in the epitope structure of the enzyme. The loss of 62% of the biological activity after DAO-anti-DAO antibodies interaction was attributed to the steric hindrance caused by binding of antibody to the enzyme molecule. A gradual loss in antigenicity during ultraviolet (UV) irradiation was observed without any significant conformational change, demonstrating the destruction of antigenic determinants. However, ethoxyformylation of nine histidyl residues with complete inactivation caused no change in immunoreactivity. The results indicate that the antigenic sites and catalytic sites are located at different positions along the polypeptide chain. Moreover, the results of lysine residue modification were suggestive of possible involvement of lysine in the antigenic determinants of DAO.

Amine Oxidase (Copper-Containing)↗
PubMed1989

Addition of glutamine to total parenteral nutrition after elective abdominal surgery spares free glutamine in muscle, counteracts the fall in muscle protein synthesis, and improves nitrogen balance.

Twenty-two patients undergoing elective abdominal surgery were given total parenteral nutrition (TPN) after the operation. The TPN contained either a conventional amino acid solution supplemented with glutamine or a conventional amino acid solution without supplementation. To study amino acid and protein metabolism, muscle biopsy specimens were taken before surgery and on the third postoperative day. The postoperative decrease in the intracellular concentration of free glutamine was less pronounced in the glutamine group (21.8 +/- 5.5%) than in the control group (38.7 +/- 5.1%; p less than 0.05). The protein synthesis was reflected in the concentration and size distribution of ribosomes. No significant changes in these parameters were seen in the glutamine group after the operation. In the control group, the total concentration of ribosomes fell by 27.2 +/- 8.5% (p less than 0.05), and the relative proportion of polyribosomes fell by 10.6 +/- 2.9% (p less than 0.01). Although there were significant changes in the control group, no significant differences in the changes of these parameters between the two groups were detected. The cumulative nitrogen loss was significantly less in the glutamine group as compared to the control group during the period studied--2.3 +/- 1.4 g versus 8.5 +/- 1.5 g, respectively (p less than 0.01). Administration of glutamine to catabolic patients is advocated.

Cholecystectomy↗
PubMed1989

Role of disulfides in biological activity and conformational stability of pig kidney diamine oxidase: evidence for two disulfide states.

Six disulfides are found to be present in pig kidney diamine oxidase and all of these are available to reducing agents under nondenaturating conditions. Disulfide reduction with dithiothreitol followed by carbamidomethylation indicated two states of disulfides, each containing three groups, distinguishable by pH dependence. The first group of three disulfides has a functional role in catalytic activity. The another class of three disulfides showed accessibility only at higher pH values and appears to be important in maintaining the three dimensional structure of the molecule. The disulfides for these two activities appear to be independent of each other. Almost similar behaviour was noticed with copper depleted apo-enzyme.

Amine Oxidase (Copper-Containing)↗