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Biomedical subjects

S Agrawal

Publications and source records attributed to S Agrawal.

At least 253 records · Page 14Linked to original sources
PubMed1994

Molecular analysis of C3 allotypes in patients with systemic vasculitis.

The third component of complement (C3) exists in two main allotypic forms, C3S and C3F, distinguished at the DNA level by a single base change. An increased frequency of the rarer C3F allele has been reported in patients with the autoantibody nephritic factor and in several other autoimmune conditions such as rheumatoid arthritis and IgA nephropathy. Studies of the immunogenetic factors predisposing to the development of systemic vasculitis have produced conflicting results and no major genetic predisposing factors have been identified. We have studied the C3S/F polymorphism in 63 patients with systemic vasculitis using DNA allotyping by the amplification refractory mutation system, a modification of the polymerase chain reaction. The allele frequency in these patients was C3S 0.71, C3F 0.29 (expected C3S 0.8, C3F 0.19; chi-squared = 5.1, P < 0.025), with the average relative risk for the development of systemic vasculitis associated with the presence of a C3F allele being 2.6. Moreover, there was a marked excess of C3FF homozygotes (11/63, [17.5%], versus 4% expected: chi-squared = 9.5, p < 0.01). The average relative risk for the development of systemic vasculitis in C3F homozygotes was 5.1, indicating a gene dosage effect. These data indicate that the C3F allele is associated with a predisposition to the development of systemic vasculitis and that C3F homozygotes are at particularly high risk. This association is the strongest genetic factor reported so far for this group of diseases.

Alleles↗
PubMed1994

Serum level of iron and transferrin in pregnancy and postpartum period.

This study presents a composite picture of haemoglobin (Hb), serum level of iron (SI), total iron binding capacity (TIBC) and percent iron saturation of transferrin in women during different trimesters of pregnancy and postpartum period. The results were correlated with age and parity. A total of 75 subjects, 15 from each trimester and 15 postpartal, were studied and compared with 15 nonpregnant normal subjects. Signs of increased iron demand, increased iron turnover and obvious iron deficiency, were demonstrated throughout pregnancy, by decrease in haemoglobin, SI, percent iron saturation of transferrin and increased TIBC; especially in older age group and multigravidae. SI, TIBC and percent iron saturation of transferrin are more sensitive indices of iron status and provide us an opportunity to replenish iron stores of an iron deficient pregnant mother at an earlier date thus preventing anaemia.

Adolescent↗
PubMed1994

Development of anti-idiotypic antibodies to HLA antigens during pregnancy.

Thirty one pregnant women whose sera were initially positive for anti HLA antibodies were retested for lymphocytotoxicity 7-9 months after delivery. In the second testing 10 women were found to have lost the cytotoxic antibodies. These sera were tested for presence of anti-idiotypic antibodies by complement dependent cytotoxicity (CDC). In all ten sera tested, CDC blocking antibody was detected by inhibition technique at different dilutions. These antibodies directed specifically against the HLA antigen of the spouse. This CDC blocking factor could be the anti-idiotypic antibody (Ab2) directed against the cytotoxic anti-HLA antibody (Ab1). In one woman who conceived a second time, repeat sample obtained at the 7th month of the second pregnancy showed reappearance of the specific anti-HLA antibody. This may suggest that the Ab1-Ab2 network is under dynamic regulation.

Antibodies, Anti-Idiotypic↗
PubMed1993

A rapid method for quantitation of oligodeoxynucleotide phosphorothioates in biological fluids and tissues.

A sensitive and simple method for the quantitation of oligonucleotide phosphorothioates in biological fluids and tissues is described. This method is based on the extraction of the oligonucleotide from the biological fluids and tissues and immobilization on a nylon membrane. The membrane-bound oligodeoxynucleotide phosphorothioate is then hybridized with labeled complementary oligonucleotide and exposed to X-ray film. The data on the film can be scanned and used to create a standard curve. The sensitivity of detection by the method described here will be useful to monitor the pharmacokinetics of oligonucleotides in bodily fluids and distribution in various tissues. The results indicate that the method is rapid and allows handling of a large number of samples at the same time.

Animals↗
PubMed1993

Self-stabilized antisense oligodeoxynucleotide phosphorothioates: properties and anti-HIV activity.

A new class of oligodeoxyribonucleotides has been designed, referred to here as 'self-stabilized' oligonucleotides. These oligonucleotides have hairpin loop structures at their 3' ends, and show increased resistance to degradation by snake venom phosphodiesterase, DNA polymerase I and fetal bovine serum. The self-stabilized region of the oligonucleotide does not interfere in hybridization with complementary nucleic acids as shown by melting temperature, mobility-shift and RNase H cleavage studies. Various self-stabilized oligonucleotides containing increasingly stable hairpin loop regions were studied for their anti-HIV activity. Pharmacokinetic and stability studies in mice showed increased in vivo persistence of self-stabilized oligonucleotides with respect to their linear counterparts.

Animals↗
PubMed1993

Long-term treatment of human immunodeficiency virus-infected cells with antisense oligonucleotide phosphorothioates.

The antiviral activity of antisense oligodeoxynucleotide phosphorothioates complementary to the tat gene, the gag mRNA, and the rev mRNA were studied in a long-term infection model. Three antisense oligonucleotides directed to the splice-acceptor site of the tat gene failed to suppress human immunodeficiency virus type 1 replication at 1 microM concentration in long-term culture. In contrast, two oligodeoxynucleotide phosphorothioates (28-mer) complementary to the gag and the rev mRNAs inhibited viral replication for > 80 days, and the antiviral activity was sequence- and length-dependent. In addition, after pretreatment of cells we could reduce the concentration of the antisense oligodeoxynucleotides by > 10-fold and still maintain the inhibition of viral replication. These results suggest that chemotherapy for human immunodeficiency virus type 1 infection with antisense oligodeoxynucleotide phosphorothioates may be achieved by an initial high-dose treatment followed by a lower maintenance dose.

Antiviral Agents↗
PubMed1993

Method for sequencing synthetic oligodeoxynucleotide phosphorothioates.

Sequencing of oligodeoxynucleotide phosphorothioate by a modified Sanger method of sequencing is described. The procedure involves ligation of synthetic oligodeoxynucleotide phosphorothioate to an oligodeoxynucleotide, referred to here as "helper oligonucleotide." The helper oligonucleotide has a region which is complementary to T7 primer. By using DNA polymerase and nucleoside triphosphate mixture, 5'-labeled T7 primer is extended onto ligated oligodeoxynucleotide phosphorothioate, which is then analyzed on gel electrophoresis.

Base Sequence↗
PubMed1993

Pharmacokinetics, biodistribution, and stability of capped oligodeoxynucleotide phosphorothioates in mice.

Several end-modified oligodeoxynucleotide phosphorothioates (S-oligonucleotides) were studied for their pharmacokinetics, biodistribution, excretion, and metabolic stability in vivo after intravenous administration in mice. The overall tissue distribution and excretion patterns of these S-oligonucleotides were found to be independent of 5' or 3' end modification studied. However, the 3' end modification proved to be of considerable importance with respect to metabolic stability of the oligonucleotide. In the case of uncapped and 5'-capped S-oligonucleotide, only 50% of intact oligonucleotide was recovered out of the total bioavailable concentration in liver and kidney. In contrast, in the case of 3'-capped oligonucleotides almost all bioavailable concentrations of 3'-capped oligonucleotide was found to be intact in kidney and liver at 24 hr after administration. These results demonstrate that superior pharmaceutical potential can be created by 3'-end modification of oligonucleotide phosphorothioates.

Animals↗
PubMed1993

Effect on embryos of injection of phosphorothioate-modified oligonucleotides into pregnant mice.

Phosphorothioate-modified oligonucleotides were injected into pregnant female mice to assess the effect on developing embryos. Injections were carried out during two different time periods, one when embryos were in preimplantation stages of development (about 3.5 days of development) and the other after implantation, when both a fetus and placenta are present (from days 9.5 to 11.5 of development). Three different phosphorothioate-modified oligonucleotides were injected. One, which had a sequence not present in the mouse genome, was used to ask whether nonspecific toxic or teratogenic effects on embryos result from treatment of the mother. A second was complementary to the mRNA of the testis-determining factor gene Sry and was used to ask whether a specific developmental pathway (i.e., sex determination) could be disrupted in embryos in vivo. The third was the complement of the anti-Sry sequence. None of these oligonucleotides reduced the frequency of successful pregnancy after mating or the average litter size from that observed in controls animals. Furthermore, examination of 291 pups or fetuses from all oligonucleotide-injected pregnant females revealed no developmental defects regardless of which sequence was used. It is concluded that injection of phosphorothioate-modified oligonucleotides into pregnant females according to the protocols described here is not toxic or teratogenic to embryos in a nonspecific way. Also, anti-Sry oligonucleotides did not influence sex determination in embryos, although there are several possible explanations for this.

Animals↗
PubMed1993

Possible role of streptokinase-induced delayed hypersensitivity and eosinophilia in pathogenesis of ankylosing spondylitis.

Present study relates to the results of investigations on 16 patients with Ankylosing spondylitis (AS). Age of the patients ranged from 16 to 44 (median 25) years. Male female ratio was 4.3:1. Sacroileitis was detected in all the patients. Seven patients each had stage 1 and 2 disease. Two other patients had stage 3 disease. Lower mean Hb per cent was detected among patients as compared to control groups. Twelve of 16 (75 per cent) patients had eosinophilia. HLA-B27 antigen was detected in 10 of 16 (62.5 per cent) patients. Streptokinase-induced delayed sensitivity was detected in 10 of 16 (62.5 per cent) patients. Anti-streptolysin 'O' antibodies were detected in 2 of 16 patients' sera. Moderate negative correlation was found between the size of induration of skin test and haemoglobin concentration (P < 0.05). Possibly, delayed hypersensitivity might induce both eosinophilia as well as anaemia among AS patients.

Adolescent↗
PubMed1992

Specific inhibition of human immunodeficiency virus type 1 replication by antisense oligonucleotides: an in vitro model for treatment.

We have developed a culture system, simulating in vivo conditions of human immunodeficiency virus type 1 (HIV-1) infection, to evaluate the long-term efficacy of antisense oligonucleotide treatment. Five oligonucleotide phosphorothioates (28-mers), complementary to different regions of HIV-1 RNA, blocked replication of the virus in a sequence-specific manner at 1 microM concentration. Variations in antiviral activity were seen among the different oligonucleotides, revealing an effect of target selection. Mismatched or random oligonucleotide phosphorothioates delayed, but did not completely inhibit, HIV-1 replication. In the case of inhibition by a splice-acceptor-site antisense oligodeoxynucleotide, a break-through phenomenon occurred after 25 days of treatment, suggesting the development of an "escape mutant." This result did not occur when the inhibitory oligodeoxynucleotides were complementary to the primary-sequence areas of the rev-responsive element and rev-1 genes. Sequential treatment of HIV-1-infected cells with a combination of different antisense oligonucleotides, each administered once, also prevented the development of escape mutants. Our results suggest that chemotherapy based on specifically targeted antisense-oligonucleotide phosphorothioates may be an effective method for reducing the viral burden in HIV-1-infected individuals at clinically achievable oligonucleotide concentrations.

Base Sequence↗