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Biomedical subjects

R C Mahajan

Publications and source records attributed to R C Mahajan.

At least 91 records · Page 5Linked to original sources
PubMed1991

Epidemiological study of parasitic infestations in lower socio-economic group in Chandigarh (north India).

When stool samples from 970 subjects belonging to lower socio-economic groups were examined for parasites, a total of 121 subjects (12.5%) i.e., 57 (12.1%) males and 64 (12.9%) females showed positive results. The overall prevalence of parasitic infestation did not correlate with sex, caste or religion and living conditions. However, the prevalence was higher in hospital employees residing in well sanitated area. Giardia lamblia (69.5%), Entamoeba, histolytica (15.7%), Hymenolepis nana (12.4%), Ancylostoma duodenale (10.7%), Ascaris lumbricoides (8.3%) and Taenia (0.8%) were the parasites seen. Mixed infections were seen in 9 subjects. Twenty families of the 196 studied had more than one family member positive for parasites. Asymptomatic positivity was high amongst all groups of subjects, and with all parasites.

Adolescent↗
PubMed1990

Post-transfusion malaria in thalassaemia patients.

A total of 125 beta-thalassaemia patients receiving repeated blood transfusions were screened by Giemsa stain, Acridine-orange stain and antigen detection for evidence of malaria infection on each visit. A total of 8 (6.4%) of the patients developed post-transfusion malaria (PMT) as confirmed by tracing the infected blood donors. A high incidence of PTM in thalassaemia patients appears to be due to the use of fresh blood and the high frequency of blood transfusions required by these patients. Antigen detection using monoclonal antibody was found to be more sensitive for diagnosis of PTM and for screening suspected donors than the conventional blood smear examination methods and is therefore recommended for routine blood donor screening to rule out malaria infection.

Animals↗
PubMed1990

Quantitative estimation of suppressor/cytotoxic and helper T cells during acute and chronic Plasmodium berghei infection.

In the present study, the percentage of lymphocyte subpopulations and their relation to T cell subsets was estimated during acute and chronic Plasmodium berghei malaria. During acute infection, a decreased percentage of T lymphocytes was observed, whereas no change was observed during chronic infection. However, no change in the percentage of B cells was observed in both types of infection. The T cell population was characterized by an increased percentage of T suppressor cytotoxic (CD8+) cells and a decreased percentage of T helper cells (CD4+) during acute infection. This resulted in an inversion of the CD8+/CD4+ cell ratio. During chronic infection no change in the CD8+ cell percentage was observed; however some increase in CD4+ cell percentage was observed in later stages. Thus failure of the immune system to overcome acute infection may be due to an increase in T suppressor cells, and maintenance of parasites at subpatent levels during chronic infection may involve the normal CD8+/CD4+ cell ratio with some increase in CD4+ cells.

Acute Disease↗
PubMed1990

Cellular immunity in pregnant and non-pregnant women with malarial infection.

A study of lymphocyte subpopulation and leucocyte migration inhibition index (LMI) in 78 pregnant and 22 nonpregnant women with malarial infection (P. vivax 60% and P. falciparum 40%) was done in a hospital in Northern India. Eighty pregnant and 20 nonpregnant women without any infection were also included in the study as controls. T-cell percentage in controls decreased to its lowest in first trimester and gradually rose to nonpregnant levels by the end of puerperium. With malarial infection, there was further drop in T-cell percentage, more so in third trimester. LMI in controls corresponded with T-cell percentage and was depressed in pregnant patients. Enhancement in LMI with malarial infection was depressed in pregnant patients maximally in the third trimester. Parity did not have any influence on these cellular immune parameters. Thus, cellular immunity status in malarial patients was found to be depressed during pregnancy especially in the third trimester.

Adolescent↗
PubMed1990

Stimulation of the absorption of macromolecules in Giardia lamblia infected mice intestine.

The absorption of 125I-labelled bovine serum albumin, gamma-globulin and alpha-lactalbumin was considerably enhanced in G. lamblia infected Swiss mice intestine compared to uninfected controls. The binding of 125I-proteins to brush border membrane was however, significantly (P less than 0.01) low in infected animals. Kinetic studies with gamma-globulin binding to brush borders revealed a decrease in the number of binding sites in infected animals (1.52) compared to controls (2.86 micrograms/mg protein) with no change in the affinity constant (47.60 micrograms/ml) under these conditions. These findings suggest that G. lamblia infection in mice leads to enhanced macromolecular absorption which seems unrelated to the binding of proteins to epithelial cell surface.

Animals↗
PubMed1990

Primaquine: its effect on cellular immune response of normal rhesus monkeys.

The effect of primaquine on the cellular immune responses (lymphocyte subpopulations and their proliferative responses with PHA, Con-A and LPS, and phagocytosis by monocytes) of normal rhesus monkeys was studied under both in-vivo and in-vitro conditions. When the lymphocytes and monocytes from normal animals were treated in-vitro with primaquine, at concentration normally attainable during therapy, a significant inhibition in blastogenic response of lymphocytes and phagocytic capacity of monocytes was noticed after 4 hours of treatment. In contrast, the in-vivo effect of primaquine treatment on these cells was innocuous. From this study it is clear that the primaquine does not act as an immunosuppresant and can be given safely to any type of malaria patient.

Animals↗
PubMed1990

Immunosuppression in murine malaria: suppressor role of macrophages and their products during acute and chronic Plasmodium berghei infection.

Marked suppression of IgM, IgG and IgA plaque forming cells was observed in mice immunized with sheep erythocytes (T-dependent antigen) during acute Plasmodium berghei infection whereas during chronic infection mild immunosuppression was observed. When mice were immunized with polyvinylpyrrolidone (T-independent antigen), suppression in the number of plaque forming cells was observed at higher parasitaemias only during acute infection whereas during chronic infection the number remained within normal limits. Adoptive transfer studies suggested that the immunosuppression was mainly mediated by macrophages and their products. The suppressor role of macrophages and their products during acute malarial infection is highlighted.

Acute Disease↗
PubMed1990

Effect of sodium stibogluconate on the status of interleukin-I production in normal & Leishmania donovani infected BALB/c mice.

Sodium stibogluconate, did not bring about significant increase in the production of IL-1, when both specific leishmanial antigen, or non specific Staphylococcus epidermidis was used as stimulus in normal uninfected animals. However, Staph. epidermidis was found to be a better stimulus as it brought about a significant increase (P less than 0.001) in IL-1 production when compared with leishmania antigen. In BALB/c mice infected with L. donovani there was a significant reduction (P less than 0.001) in IL-1 levels on various post infection days irrespective whether Staph. epidermidis or leishmanial antigen was used as stimulus when compared with controls. IL-1 levels were significantly increased (P less than 0.05) when L. donovani infected animals were treated with SSG, after 14 days post infection, irrespective of the stimuli used.

Animals↗
PubMed1990

Reactive oxygen species generation by Kupffer cells and blood monocytes of mice infected with Plasmodium berghei and the chloroquine treatment.

Generation of reactive oxygen species (ROS) by blood monocytes and Kupffer cells of normal and Plasmodium berghei infected mice treated at different levels of parasitaemia with chloroquine, were studied. Cells isolated at lower level of parasitaemia (less than 2%) produced ROS within the range of normal animals, whereas ROS production by the cells isolated from the animals at higher level of parasitaemia (greater than 20%), was significantly higher even without stimulation with latex particles. The ROS generation capacity of both normal and infected animals was less after the chloroquine treatment. This inhibitory effect of chloroquine may be beneficial in protecting the host from the adverse effect of reactive oxygen species by controlling their overproduction.

Animals↗
PubMed1990

Role of delayed type hypersensitivity responses in protection during chronic Plasmodium berghei infection as evidenced by homing of radiolabelled bone marrow cells and contact sensitivity.

A comparative study of specific and non-specific immunosuppression has been carried out in acute and chronic Plasmodium berghei infected mice in an in vivo system. In our previous studies, immunosuppression during acute P. berghei infection was attributed to T lymphocytes when we studied modulation of blastogenic response of lymphocytes in an in vitro system. In the present study, delayed type hypersensitivity (DTH) was evident from the homing of radiolabelled bone marrow cells into the delayed lesions of antigen challenged foot pads during chronic infection. This response was suppressed during acute infection especially in early stages. A greater concentration of bone marrow cells in the liver and spleen occurred during chronic infection in comparison with acute infection. When radiolabelled bone marrow cells from infected mice were injected into the normal mice previously given malaria antigen in foot pads, no significant change in homing pattern in liver, spleen or foot pads was observed. Contact sensitivity to picryl chloride was suppressed during acute infection, but was intact during chronic infection. Since these responses are mediated by T lymphocytes, significance of these responses is discussed.

Acute Disease↗
PubMed1990

Mechanism of tissue damage through free oxygen radicals during hepatic amoebiasis in guinea pigs.

The capacity of Kupffer cells and blood monocytes to release free oxygen radicals was studied by chemiluminescence (CL) response during hepatic amebiasis in guinea pigs. Guinea pigs infected with Entamoeba histolytica intramesenterically were sacrificed on days 0, 2, 5 and 8 post-infection. Hepatic lesions were graded I-IV. A significant increase in the CL response was observed from day 2 post-infection and it increased with the progress of infection. Maximum increase was observed on the 8th post infection day. Animals with grade III or IV hepatic lesions had significantly elevated CL response. The degree of hepatic lesions correlated well with the CL response (P less than 0.01). It is postulated that tissue damage during hepatic amoebiasis may be mediated through enhanced release of free oxygen radicals by Kupffer cells and blood monocyte.

Animals↗
PubMed1989

Immunological response in experimentally reactivated toxoplasmosis in mice.

Both humoral and cell-mediated immune responses were studied in reactivated toxoplasma infection in mice. The infection was established by immunosuppressing chronically infected animals by thymectomy followed by irradiation. The reactivated infection was confirmed by reappearance of toxoplasma tachyzoites in peritoneal exudate. The animals survived until the 8th day post thymectomy. The percentage of splenic T lymphocytes was depressed after 4th day post thymectomy in both the uninfected thymectomized and infected immunosuppressed animals as compared to the intact uninfected controls and intact chronically infected animals. However, there was no significant change (P greater than 0.05) between the uninfected immunosuppressed control and infected immunosuppressed mice. When the infection progressed to more acute phase there was significant depression (P less than 0.01) in the percentage of T lymphocytes in comparison to the uninfected thymectomized mice. However, there was no change in the percentage of B lymphocytes (P greater than 0.05). The function of lymphocytes as assessed by blast transformation was depressed in the presence of nonspecific mitogens, i.e. phytohemagglutinin and concanavalin A until the end of the study. The response to toxoplasma antigen was increased during early stages in the infected immunosuppressed mice (stimulation index = 4.15 +/- 0.1 and 4.5 +/- 0.15 on 4th and 6th day post thymectomy). On the 8th day post thymectomy, there was a sudden fall in the stimulation index (3.5 +/- 0.11). The antitoxoplasma antibodies as detected by indirect hemagglutinin and fluorescence analysis and enzyme-linked immunosorbent assay (ELISA) tests and toxoplasma-specific IgM antibodies as detected by ELISA test were present throughout the study period though at low levels. The significance of these findings is discussed.

Animals↗
PubMed1989

Lectin activity of axenic and xenic Giardia lamblia trophozoites.

The membrane bound lectin of Giardia lamblia is though to play an important role in the selective colonization of the proximal small intestine by the parasite. The lectin obtained from xenic lysetes of G.lamblia gave a titre of more than 1:2048 in the hemagglutination test with rabbit erythrocytes, whereas the axenic lysates required pre-treatment with proteases (trypsin and pronase) in order to obtain a titre of 1:32. Similar behavior was exhibited by enterocytes of the mouse small intestine when tested for agglutination. The activation of xenic trophofzoites by the intestinal proteases and the probable role of bacterial enzymes has been discussed.

Animals↗
PubMed1989

Changes in the superoxide anion generating capacity and respiratory burst enzymes of peripheral blood monocytes of monkeys during acute Plasmodium knowlesi infection.

The superoxide anion generation profile of peripheral blood monocytes of rhesus monkeys was investigated during the different stages of an acute Plasmodium knowlesi infection. An initial increase in superoxide anion was followed by a significant decline (P less than 0.001), paralleled by a drop in NADPH oxidase activity; there was no alteration in the activity of the hexose monophosphate shunt enzymes. This lowered activity of the NADPH oxidase, with the resulting decreased O2 generation, might be responsible for the failure of the animals to control the parasitaemia; as a result they succumbed to the infection.

Animals↗
PubMed1989

Role of lysosomal enzymes in tissue damage during hepatic amoebiasis. An experimental study.

Two key lysosomal enzymes, N-acetyl-beta-glucosaminidase and beta-glucuronidase of Kupffer cells and blood monocytes were studied in guinea pigs infected intramesenterically with E. histolytica. The animals were sacrificed on days 0, 2, 5 and 8 post-infection. The enzyme levels in the cell lysate and supernatants of both Kupffer cells and blood monocytes were significantly higher (P less than 0.01) in the infected animals compared with the controls. This increase was more marked on the 5th and 8th days post infection (P less than 0.001). The alteration in enzyme levels was higher in Kupffer cells than in blood monocytes (P less than 0.05). The enzyme levels increased exponentially with the severity of the hepatic lesions. A direct correlation was observed between the enzyme levels and the severity of the hepatic lesions (P less than 0.01). Hence, the role of lysosomal enzymes, released by activated mononuclear phagocytic cells, in the pathogenesis of hepatic amoebiasis is postulated.

Acetylglucosaminidase↗
PubMed1989

Mechanism of innate immunity to amoebic infection in guineapigs.

The direct lymphocyte cytotoxicity and antibody dependent cell mediated cytotoxicity against Entamoeba histolytica was studied in 3-4 wk old and 8-10 wk old guineapigs. Both these parameters were significantly increased in splenic cells in the older animals. This might be due to maturation of the immune system or to natural infection by related parasite, leading to immunity.

Aging↗
PubMed1989

Lymphokine mediated microbicidal activity of peritoneal macrophages from Leishmania donovani infected and drug treated BALB/c mice.

The resident peritoneal macrophages from untreated mice develop potent microbicidal activity against amastigotes of Leishmania major and Leishmania donovani after in vitro exposure to lymphokines (LK) from mitogen stimulated spleen cells. However, to the best of our knowledge, the response of L. donovani infected peritoneal macrophages from already infected/treated animals to LK has not been investigated. Therefore in the present study, the effect of LK on infected macrophages from BALB/c mice following specific infection and subsequent treatment with sodium stibogluconate has been investigated. As the infection progressed, a decrease in percent microbicidal activity was noticed. An attempt was also made to treat the animals on different post infection days and reinfect them in vitro. Infection could not be produced in vitro in late treatment groups when the treatment was given on 14 days and 21 days post infection. Whereas, macrophages obtained from animals treated on 7 days post infection (early treatment) could be infected in vitro. However, only 50% of the cells got infection. This infection was eliminated when the cells were exposed to LK for 72 hours.

Animals↗