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Biomedical subjects

R Ali

Publications and source records attributed to R Ali.

At least 109 records · Page 6Linked to original sources
PubMed1994

Cokeromyces recurvatus, a mucoraceous zygomycete rarely isolated in clinical laboratories.

Cokeromyces recurvatus Poitras was isolated from an endocervical specimen obtained from a 37-year-old, insulin-dependent diabetic. The patient's diabetic condition had been well controlled for 10 years, and she had no other known medical problem. This is only the fourth time that this zygomycete has been recovered from a human source. While there was no evidence of tissue invasion in the present patient, the observation of fungus-like structures in two separate Papanicolaou-stained cervical smears prepared 1 year apart suggests that C. recurvatus may be capable of colonizing endocervical tissue.

Adult↗
PubMed1994

Autoantibodies-like antigen binding characteristics of induced antibodies against polylysine-polyglutamate complex.

Rabbits immunized with polylysine-polyglutamate complex induced high titer antibodies. The immune IgG exhibited high degree of specificity towards the immunogen. In a competition assay, nDNA, heat denatured DNA and total buffalo thymus RNA were inhibitory. An appreciable binding with polyglutamate, poly(rG).poly(dC) poly(dG).poly(dC), cardiolipin, poly(dA-dU). Poly(dA-dU) and Z- or Z-like conformations demonstrates the polyspecificity of induced antibodies. The immunological specificity of induced antibodies was comparable to autoantibodies derived from SLE. The results might be of some help in understanding the etiology of autoimmune process.

Animals↗
PubMed1994

Modification of pig kidney diamine oxidase with ethoxyformic anhydride and rose bengal: evidence for essential histidyl residue at the active site.

Purified diamine oxidase from pig kidney showed time dependent inactivation by ethoxyformic anhydride and photooxidation with Rose Bengal. Modification of histidine either by ethoxyformic anhydride or by Rose Bengal was the sole cause of enzyme inactivation. The inactivated enzyme showed no significant perturbation in structure. The protection against photooxidation of enzymatic activity and histidine residues by inhibitor (phenylenediamine hydrochloride) and substrate (putrescine) protected the photooxidation of two histidyl residues. However, kinetic analysis of photooxidation of histidyl residues and inactivation of the enzyme conclusively suggested the involvement of one histidyl residue, which seems to be located at the active site of diamine oxidase.

Amine Oxidase (Copper-Containing)↗
PubMed1993

The prescription of methadone for opiate dependence in Australia, 1985-1991.

OBJECTIVE: To describe the rates and patterns of prescription of methadone for opiate dependence in Australia from 1985 to 1991. DESIGN: Data on the numbers of Australians prescribed methadone in States and Territories were used to calculate prevalence rates of prescription of methadone. RESULTS: In 1985, Queensland had the highest rate of prescription of methadone. After the establishment of the National Campaign Against Drug Abuse, rates increased in most jurisdictions. Assessment procedures and prescribing practices, such as private prescription of methadone, appear to have markedly affected rates of prescription in some States. CONCLUSION: Large differences in rates of methadone prescription have occurred in Australian States and Territories. There are inadequate data to explain how rates of prescription are related to the prevalence of opiate use. Investigations of prevalence of injecting opiate use, demand for treatment and clinic practices are needed to explain these patterns fully.

Adolescent↗
PubMed1993

The effect of hydroxyl radical on the antigenicity of native DNA.

Hydroxyl free-radical mediated in vitro modification of native calf thymus DNA showed single-strand breaks, decrease in melting temperature and structural alteration of purine and pyrimidine bases. Experimentally induced antibodies against modified DNA exhibited polyspecificity. Native DNA, RNA and synthetic polynucleotides in B-conformation were found to be an effective inhibitor of induced antibody-immunogen interaction. Naturally occurring human anti-DNA autoantibodies showed enhanced recognition of modified DNA as compared to native polymer. IgG isolated from anti-DNA antibody-positive SLE sera by Protein A-Sepharose 4B chromatography were affinity purified on nDNA-(polylysyl-Sepharose 4B) matrix. In competitive binding experiments, the affinity-isolated IgG showed almost equal recognition of both native DNA and hydroxyl radical modified DNA. The possible role of hydroxyl radicals in the etiopathogenesis of SLE has been discussed.

Animals↗
PubMed1993

Polynucleotide specificity of anti-reactive oxygen species (ROS) DNA antibodies.

Hydrogen peroxide in the presence of short wavelength UV light was able to induce alterations in native DNA fragments of 300 bp (ROS-DNA), thereby rendering it immunogenic in experimental animals. The specificity of induced antibodies was investigated by direct binding and competition ELISA. Inhibition studies revealed nearly 89% inhibition in the antibody binding by the immunogen and recognition of native B-, A- and allied conformations presented by various synthetic polynucleotides. Gel retardation assay reiterated the formation of immune complexes between induced antibodies and native and ROS-DNA fragments. It was observed that naturally occurring anti-DNA autoantibodies from systemic lupus erythematosus (SLE) sera recognize ROS-DNA. The comparison of the specificities of anti-DNA autoantibodies from 10 SLE patients showed a 20-50-fold preference for ROS-DNA over native DNA. These results demonstrate that anti-DNA antibodies can be induced by ROS-DNA, and that some of the autoimmune DNA binding antibodies found in SLE may result from response to reactive oxygen species.

Animals↗
PubMed1993

Assay of antinuclear antibodies by ELISA using nuclei as antigen.

An enzyme-linked immunosorbent assay to detect antinuclear antibodies in the sera of patients with autoimmune diseases is described. Goat liver nuclei were immobilized on polystyrene plates and antinuclear antibodies were used to standardize the assay. The effects of variables, such as the nuclei concentration, conditions of nuclei storage, and the length of the incubation period were investigated on the assay. Prototype sera with known antibody specificity were used to evaluate the assay. The method described is highly sensitive, autoantibodies being detectable at serum dilutions of 1:1000 or higher. According to the intra- and inter-assay coefficient of variation, the results were highly reproducible.

Animals↗
PubMed1993

Serum lactate dehydrogenase in head and neck malignancy patients.

50 patients of head and neck malignancy were selected for this study while excluding those associated with renal, hepatic, cardiac and metabolic diseases. Age and sex matched even number of controls were also included for comparison. Serum LDH levels in the control group were 124.2 +/- 3.50 I.U./L. Higher levels of LDH were observed in patients with malignancy of head and neck (335.50 +/- 21.60 I.U./L, P < 0.001). Serum LDH level was also related to histopathological stage of malignancy, being higher in poorly differentiated tumour as compared to moderate and well differentiated malignancy. Patients without metastasis had insignificantly lower serum LDH levels as compared to those with metastasis.

Adult↗
PubMed1993

B-->Z transition in native calf thymus DNA depends on its microenvironment.

Z-DNA forming potentiality of native calf thymus DNA was investigated under varying experimental conditions. Ethidium intercalation and Scatchard analysis data showed decreased binding of ethidium to nDNA at 4.27 M NaCl. A comparison of ethidium binding to DNA in low and high salt indicated the formation of Z-DNA. The binding of monoclonal anti-Z-DNA antibody to nDNA fragments brominated in high salt reiterated the transition of B-->Z conformation.

Animals↗
PubMed1992

Reactive oxygen species modified DNA fragments of varying size are the preferred antigen for human anti-DNA autoantibodies.

In vitro studies were carried out to determine if reactive oxygen species modified DNA molecules are the preferred antigen for anti-DNA antibodies found in SLE sera. Reactive oxygen species were generated by 254 nm irradiation of hydrogen peroxide. Single stranded breaks, decrease in Tm and modification of adenine (21.7%) and thymine (48%) were the major effects observed on native DNA fragments of 300 bp in length. The ROS-modified DNA showed increased binding with naturally occurring anti-DNA autoantibodies as compared to unmodified DNA fragments. These results were substantiated by competition ELISA. Measurement of binding with DNA fragments of varying size revealed considerably increased binding as the fragment size increased from 50 bp to 800 bp. The relative affinity of anti-DNA IgG for ROS-modified and native DNA fragments of 300 bp were in the order of 6.26 x 10(-8) M and 4.07 x 10(-8) M, respectively.

Animals↗
PubMed1992

Naturally occurring SLE anti-DNA antibodies recognize unique conformation on DNA-lysine photoadduct.

Native calf thymus DNA has been covalently modified with lysine under UV-A light. Human autoantibodies on purification through affinity column of native DNA linked to polylysyl-Sepharose 4B showed almost equal recognition of DNA and photoadduct. The recognition of DNA-lysine photoadduct by the affinity-purified autoantibodies might be helpful in understanding their origin in SLE vis-à-vis the role of positively charged amino acids in the pathogenesis of autoimmune diseases.

Animals↗
PubMed1992

Antibodies against free radical modified native DNA recognize B-conformation.

Hydroxyl radical, a prominent entity of reactive oxygen species, is known to modify cellular DNA and has been implicated in several human diseases. In the present studies, the radical was generated by exposure of hydrogen peroxide to 254 nm light in the presence of native calf thymus DNA. Single strand breaks, decrease in Tm and modification of adenine and thymine were some of the modifications observed in nDNA. Antibodies induced in experimental animals against the modified DNA were immunogen specific. These antibodies also recognize native B-conformation. It was observed that naturally occurring anti-native DNA autoantibodies from SLE sera recognize modified DNA in direct binding and competition ELISA. Gel retardation assay reiterated the formation of immune complexes between induced antibodies and DNA fragments of around 300 bp (B-conformation). The possible significance of these findings in the etiology of SLE has been discussed.

Animals↗
PubMed1992

Human autoantibody binding to multiple conformations of DNA.

Systemic lupus erythematosus and rheumatoid arthritis in humans are characterized by circulating and tissue fixed autoantibodies reactive with self antigens including nucleic acids and other nuclear components. Native calf thymus DNA (B-form), DNA.RNA hybrid (A-form), and left handed DNA (Z-form) were reactive with autoantibodies derived from SLE sera. Inhibition studies suggest that antibodies are recognizing multiple conformations presented by altogether different polymers and A- or Z-DNA might be the immunogenic stimulus for the production of antibodies cross reactive with native DNA.

Antibodies, Antinuclear↗
PubMed1992

DNA repair, cancer and gene therapy.

Fidelity of DNA synthesis is pivotal to our understanding of fundamental biological processes. An organism must replicate and repair its DNA with high accuracy and precision in order to maintain its genetic activity. DNA repair pathways enable cells to offer enhanced resistance to deleterious effects of chemicals and radiations (Lindahl, 1982). A number of pathways have been described e.g. the error-prone SOS repair (that lacks fidelity of repair process),the error-proof adaptive repair of alkylated DNA and inducible response to oxygen radical damage in DNA. These different circuits are under positive regulatory controls. However, the biochemical strategies employed to generate specific protein activators differ among the pathways. Although, the universally occurring repair activities seem to serve efficiently to counteract malignancy, error-prone polymerase and plasminogen activator have been instrumental in tumorigenesis, the process that proceeds by cascading of genetic errors (Sancar and Sancar, 1988).

Journal Article↗