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Biomedical subjects

D Subrahmanyam

Publications and source records attributed to D Subrahmanyam.

At least 55 records · Page 3Linked to original sources
PubMed1986

Unresponsiveness of lymphocytes in patent filarial infection: modulation by diethylcarbamazine.

The lymphocytes of lymph nodes and spleen of Mastomys natalensis infected with Litomosoides carinii were unresponsive to specific filarial antigens during patent stage of the infection. The effect of diethylcarbamazine (DEC) on these responses has been investigated. DEC administered orally at 150 mg/day for 5 days to the animals reduced markedly the circulating levels of microfilariae. At this stage the lymphocyte proliferative responses improved to specific microfilarial antigens. On follow-up a month later when the DEC effect waned and microfilaremia again sets in, both the lymph node and the spleen cells became unresponsive to specific microfilarial antigens. These findings indicate that decrease in circulating parasites on treatment with DEC could restore the cellular responsiveness to parasite antigens.

Animals↗
PubMed1985

Serum dependent cell-mediated immune reactions to Brugia pahangi infective larvae.

Fresh normal rat serum (fNRS) promoted adherence and cytotoxicity of albino rat neutrophils and macrophages to Brugia pahangi infective larvae (L3) in vitro. EDTA and not EGTA abolished the adherence activity suggesting the involvement of complement components via the alternate pathway. C3 molecules were detected on the surface of the parasite by immunofluorescence. fNRS depleted of complement by treatment with Zymosan A or of factor B by heating at 50 degrees C for 20 min, failed to promote cell adherence to the parasite. fNRS and cells from albino rat were more potent in inducing cytotoxicity to L3 than those from jird or Mastomys which may reflect the greater resistance offered by the albino rat to B. pahangi infection. In the presence of IgG and a heat labile factor, possibly complement, of immune serum, neutrophils and macrophages and to a lesser extent eosinophils adhered to and killed the larvae. Immune sera raised against microfilariae of different filarial parasites promoted cell-mediated cytotoxicity to B. pahangi L3 suggesting sharing of antigens between the two stages.

Animals↗
PubMed1985

Cellular immune competence in bancroftian filariasis.

Lymphocyte proliferative responses to homologous and heterologous filarial antigens, mitogens and purified protein derivatives (PPD) were analysed in a group of 37 subjects from an area endemic for bancroftian filarial infection. The majority of the subjects without any clinical or parasitological evidence of filariasis (endemic normals) reacted with homologous microfilarial antigens only. Non-treated patients with patent microfilaraemia, did not respond to homologous of heterologous microfilarial antigens. In contrast, diethylcarbamazine (DEC)-treated microfilaraemic patients, reacted with homologous filarial antigens. Patients with elephantiasis reacted to microfilarial and adult worm antigens. Response to PPD was marginally depressed in patent microfilaraemic patients and a rise was observed in elephantiasis cases. Endemic normals exhibited normal response to PPD. Responses to mitogens were depressed throughout the course of the infection.

Adult↗
PubMed1985

Brugia malayi: serum dependent cell-mediated reactions to microfilariae.

Sheathed and exsheathed microfilariae of Brugia malayi are killed by normal rat cells in the presence of immune serum in vitro. Immune serum heated at 56 degrees C for 1 hour lost this activity which was largely restored by the addition of fresh normal rat serum. EDTA but not EGTA abolished this activity indicating the operation of complement by alternate pathway. Fresh normal rat serum alone promoted cellular adherence without exerting cytotoxicity to the microfilariae. The activity in the immune serum could be removed with Staphylococcus aureus cells containing Protein A or anti-IgG antiserum. The activity could also be absorbed to and eluted from Protein A--sepharose CL-4B suggesting the involvement of IgG. Neutrophils and macrophages participate in the antibody dependent cell-mediated cytotoxicity phenomenon. Eosinophils while adhering to the microfilariae exert cytotoxicity only to the exsheathed parasites.

Animals↗
PubMed1984

Separation of viable microfilariae free of blood cells on Percoll gradients.

A consistent and reproducible method is described for isolating pure populations of microfilariae of Litomosoides carinii, Brugia pahangi, B. malayi and Dipetalonema viteae, free of cells, from blood, by density gradient centrifugation on Percoll in 0.25 M sucrose. The recovery of the microfilariae was 85 to 97%.

Animals↗
PubMed1984

Microfilarial periodicity in Mastomys natalensis.

The microfilarial level in the peripheral blood of Mastomys natalensis infected with the filarial parasites, Litomosoides carinii, Brugia pahangi, B. malayi and Dipetalonema viteae was monitored at two-hour intervals for 24 hours. The microfilariae of B. pahangi and B. malayi exhibited nocturnal and diurnal subperiodicity, respectively; no such periodicity was seen in L. carinii and D. viteae infections. The level of B. pahangi and D. viteae microfilariae in peripheral blood was significantly increased when the host was anaesthetized with diethylether or pentothal sodium. Ether-induced anaesthesia had no effect on the level of B. malayi microfilariae but pentothal was most effective. The peripheral blood count of L. carinii microfilariae tended to decrease in the anaesthetized animals but the reduction was not statistically significant.

Anesthetics↗
PubMed1984

The effect of p-aminobenzoic acid and folic acid on the development of infective larvae of Brugia malayi in Aedes aegypti.

Adult Aedes aegypti mosquitoes, infected with the subperiodic Brugia malayi, were found to enhance the development of the filarial parasites to the infective stage when they were exposed to a cotton pad soaked in 10% sucrose solution containing p-aminobenzoic acid (PABA) in 0.001, 0.005, 0.01, 0.05 and 0.1% concentrations. Similarly, larval development increased when the mosquitoes were fed with folic acid at 0.001, 0.01 and 0.1% concentrations. This stimulation was more when PABA or folic acid was given prior to the infected blood meal through the developmental period of the larvae. The data thus suggest that PABA and folic acid are nutrients for the development of B. malayi-microfilariae to the infective stage in A. aegypti.

4-Aminobenzoic Acid↗
PubMed1984

Brugia pahangi: serum-dependent cell-mediated reactions to sheathed and exsheathed microfilariae.

The immune mechanisms operating on the sheath and the cuticle of the Brugia pahangi microfilariae have been studied in vitro. The intact and exsheathed parasites were used for this purpose with serum from albino rats immunized with sonicated homogenates of the parasites as the source of antibodies. The IgG component of the serum was found to promote adherence of rat leucocytes and death of the sheathed and exsheathed parasites in presence of fresh normal serum. EDTA and EGTA abolished the adherence activity suggesting the involvement of complement components via the classical pathway. Both macrophages and neutrophils participate in this reaction. Eosinophils exhibit marginal activity only on exsheathed parasites. The intensity of adherence and killing by neutrophils in the presence of immune serum was greater with the exsheathed microfilariae than with the sheathed ones.

Animals↗
PubMed1984

Effect of diethylcarbamazine on serum-dependent cell-mediated immune reactions to microfilariae in vitro.

The effect of diethylcarbamazine citrate (DEC) on serum-dependent cellular adherence and cytotoxicity to sheathed and exsheathed microfilariae of Litomosoides carinii and Brugia pahangi in vitro has been investigated. DEC at 5 micrograms/ml promoted antibody-mediated neutrophil adherence and cytotoxicity with sheathed L. carinii microfilariae. With exsheathed parasites, the drug promoted significantly complement-and antibody-mediated cellular adherence and cytotoxicity. In the case of B. pahangi, antibody-dependent cell-mediated cytotoxicity (ADCC) of neutrophils to sheathed and exsheathed microfilariae were similarly stimulated by DEC. Pre-incubation of microfilariae with DEC promoted the cellular adherence and cytotoxicity whereas pre-incubation of cells had no such effect. DEC stimulated the adherence of eosinophils to both sheathed and exsheathed microfilariae of the two species but the adherence resulted in cytotoxic effect only on the L. carinii microfilariae. DEC at higher concentrations (100 or 500 micrograms/ml) inhibits these processes. Data on the role of different serum factors involved in this phenomenon have been presented and discussed.

Animals↗
PubMed1983

Comparative efficacy of some benzimidazoles and amoscanate (Go.9333) against experimental filarial infections.

The comparative efficacy of mebendazole, fenbendazole, oxibendazole, oxfendazole, albendazole, flubendazole and micronized amoscanate (particle size 5-8 micron) against Litomosoides carinii and Brugia pahangi infections in Mastomys natalensis was studied on administration of the compounds per os (150 mg/kg/day for 5 days) and subcutaneous (100 mg/kg/day for 5 days) routes. It was found that benzimidazoles when given by the oral route had no effect on adults of L. carinii and B. pahangi. With most of these compounds there was a rise in microfilariae before registering a fall to varying degrees in the peripheral circulation. There was a gradual but effective reduction of microfilariae of L. carinii in animals treated orally with mebendazole (99%), flubendazole (95%) and oxfendazole (85%). No such effect was seen against B. pahangi microfilariae. On subcutaneous administration, all the benzimidazoles with the exception of fenbendazole exhibited marked macrofilaricidal activity against L. carinii. Such activity was not seen with oxibendazole, oxfendazole and fenbendazole against adults of B. pahangi. Amoscanate exhibited superiority over the benzimidazoles in that the compound eliminated microfilariae and adult worms of both L. carinii and B. pahangi species when given by oral and subcutaneous routes.

Aniline Compounds↗