Biomedical subjects
Publications and source records attributed to A Rattan.
This is the first report of Pneumocystis carinii infection seen in patients with AIDS in India. Two of the three patients were of Indian origin while the third was an American tourist. This report indicates that the technical problem of demonstrating P carinii may be an important factor underlying the diagnosis of PCP.
Seven clones of murine monoclonal antibodies specific for group-A streptococci were generated. All of them were of IgM isotypes and recognized trypsinized as well as nontrypsinized group-A streptococci and polysaccharide. These were devoid of reactivity with streptococci-B, -C, -G and Staphylococcus aureus. Polyclonal antibodies against group-A polysaccharide (APS) were also raised in rabbits by linking APS to bovine serum albumin, and rendered monospecific by adsorption. Latex agglutination assays were developed employing both types of antibodies. The assay employing monospecific polyvalent antibodies had a sensitivity of 12.5 ng APS/ml as compared to 1 microgram APS/ml for latex sensitized with monoclonal antibodies. Both assays were specific, as no agglutination was observed with polysaccharides obtained from streptococci-B, -C, -G, Staph. aureus, Cornybacterium diptheriae, Candida albicans, Candida spp., Morexella catarrhalis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Streptococcus agalactiae, Strep. pneumoniae. Salmonella typhi and S. paratyphi A and B. Throat swabs from children obtained in duplicate, when tested for the presence of streptococci-A, showed a good correlation of the results obtained by latex agglutination assay with the microbial culture test and serogrouping.
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Circulating immune complexes (CIC) were estimated in 28 cases of Non-Hodgkin's lymphomas, Hodgkin's disease, bone and soft tissue sarcomas in the pediatric age group by polyethylene glycol (PEG) precipitation and latex agglutination inhibition (LAI) techniques. Results were compared with 25 age-matched controls. Highly significant CIC values were obtained by LAI technique (P less than 0.01) as compared to PEG pptn technique (P less than 0.05) in malignancy. However, seropositivity for CIC in lymphomas and Hodgkin's disease was 85.71 per cent by LAI test as compared to 57.14 per cent by PEG pptn test. In sarcoma group, seropositivity for CIC was 57.11 per cent by LAI test and 28.57 per cent by PEG pptn test. Combination of both these tests increases the sensitivity of immune complex detection in serum of cancer patients. CIC begin to rise in serum in early stages of neoplastic transformation, and the level of CIC is directly proportional to proliferating tumour mass in vivo.
Serological evidence of infection with verotoxin-producing Escherichia coli (VTEC) was sought in 28 patients suffering from haemolytic uraemic syndrome (HUS) and 25 age- and sex-matched controls. ELISA was used to detect anti-lipopolysaccharide (LPS) antibodies to E. coli strains O157, O111, O26 and NCTC 10418, a non-VTEC strain, and Shigella dysenteriae O1. Sera from 19 of the HUS patients but from none of the 25 controls had significant antibody levels to the verotoxin-producing bacteria. Sera from 13 patients reacted with only one LPS of the four verotoxin-producing bacteria; sera from six reacted with more than one LPS antigen but not with LPS of E. coli NCTC 10418. Paired sera taken 2-3 weeks apart were obtained from 20 HUS patients; 14 of these had high levels of antibody in the acute phase sample. Analysis of antibody levels in the convalescent sera showed that one patient had an increase, one was unchanged and 12 patients had a decrease in antibody to the verotoxin-producing bacteria.
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Circulating immune complexes (CIC) were estimated in 22 patients of breast carcinoma, 25 healthy control volunteers and 10 follow-up cases after mastectomy by polyethylene glycol precipitation (PEG pptn) test and Latex agglutination inhibition (LAI) test. CIC levels increased with advancing stage of breast carcinoma. Significant increase in CIC levels was observed in stage II (p < 0.01), followed by highly significant increase in stage III and IV (p < 0.01) as compared to the control group. Sharp decrease in CIC levels was observed three months after radical surgery in 9 post-operative patients. One patient remained seropositive by both tests, followed by a fatal outcome after four months follow-up. Seropositivity for CIC by PEG pptn test in patients of breast carcinoma was 72.72 percent as compared to 81.81 percent by LAI test. Combination of both tests increased total CIC positivity by 90.9 percent. Clinical utility and prognostic significance of CIC in monitoring breast carcinoma patients has been demonstrated by our study.
Circulating immune complexes (CIC) were estimated in 100 cancer patients and 25 healthy control volunteers by means of the polyethylene glycol (PEG) precipitation test and latex agglutination inhibition (LAI) test. Pathological levels of CIC were found in 47% of the patients by PEG precipitation test and in 59% of the patients by LAI test; both tests were positive in 33% of the patients. Consequently, the use of the two assays resulted in 73% seropositivity for CIC. The PEG precipitation test detects antigen-antibody complexes formed in the ratio of 2:1 (Ag2Ab), while the LAI test could detect immune complexes formed over an extended range of antigen-antibody ratio including complexes as small as 8S. CIC values were significantly higher by combined assays (P less than 0.001) as compared to individual assays (P less than 0.01) when compared with the control group. It was found that 75% of post-operative follow-up patients became seronegative for CIC in the combined assays, whereas the 25% of post-operative patients who remained seropositive for CIC showed recurrence within three months after surgery. Immune-complex deposition was demonstrated on malignant cells in vitro by direct immunofluorescence studies in 73.3% of patients, while 60% of patients revealed complement-fixing antigen-antibody complexes. It was found that 20% of patients showing positive immunofluorescence with anti-C3-antisera had decreased levels of CIC. Complement-mediated cytotoxic injury results in reduction of tumor cell mass and subsequent decrease in CIC. Necrotizing and leucocytoclastic vasculitis in the tumor mass was initiated by raised CIC levels in vivo in 71% of patients. Necrosis of malignant tumors was seen in 58% of patients, and hemorrhage in 36% of patients. These changes were considered to be an aftermath of immuno-complex vasculitis initiated by CIC.
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One hundred children in the age group 6 months to 5 years were investigated for cell-mediated immune response in relation to their nutrition. The nutritional status was assessed by the Wellcome classification. The majority (54 per cent) of children had marasmus. Absolute lymphocyte count was found to be significantly low (P less than 0.01) in all malnourished groups except in mild forms of undernutrition. Small lymphocytes were also found to be significantly decreased (P less than 0.001) in malnourished children. A significant depression (P less than 0.001) was observed in the percentage and absolute T cells in all the malnourished children with kwashiorkor who showed the maximum depression of counts. All the control children showed DNCB skin reactions above grade 2+ while only 39 per cent of malnourished children showed reaction of this grade. After 4-6 weeks of dietary therapy, T cell counts were comparable with control values and DNCB skin test returned to normal in more than 75 per cent of cases.
Three hundred and seventeen recent clinical isolates were tested for in vitro susceptibility to the three cephalosporins available in India--cephalexin, cefazolin and cefotaxime by the Kirby--Bauer disc diffusion method. Cefazolin was the most effective cephalosporin against Gram positive cocci (71.8% sensitive) followed by cefotaxime (62.7%) and cephalexin (52.7%). Cefotaxime was very effective against commonly isolated Gram negative bacilli with only 10 (8.8%) isolates being resistant to it while 44 (39%) and 65 (57.5%) were resistant to cefazolin and cephalexin, respectively. All isolates of Pseudomonas aeruginosa were resistant to cephalexin and cefazolin and only 29 (32.6%) were sensitive to cefotaxime.
The cell mediated immune response in 45 patients of cancer, head and neck was evaluated by various parameters and compared with 20 control cases. (DNCB) Dinitrochlorobenzene cutaneous reactivity in vivo was compared with T lymphocytes, estimated as active rosette forming cells (ARFC) and Total rosette forming cells (TRFC) in peripheral blood. The ratio of TRFC/ARFC was studied in various histological subtypes of cancer head and neck. Lymphocytic infiltration around tumor mass was correlated with peripheral blood lymphocyte (PBL), ARFC and TRFC levels in blood. Significant difference was noted in the level of peripheral blood lymphocytes (PBL). TRFC and ARFC between control cases and cancer patients. There was a marked increase in all three parameters i.e. PBL, TRFC, ARFC (P less than 0.001) and a positive DNCB reaction in Adenocarcinoma of nasopharynx, thyroid and salivary gland and a significant decrease in Squamous cell Carcinoma of oral cavity and larynx (p less than 0.001) associated with impaired DNCB sensitivity. These parameters serve as an assessment of the degree of immune reactivity of the host to the malignant tumours.