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Biomedical subjects

S Bose

Publications and source records attributed to S Bose.

At least 163 records · Page 9Linked to original sources

Evaluation of precorneal tear film in leprosy.

The present study analyses the precorneal teat film using schirmer's test and tear film breakup time (BKUT) in 400 eyes of patients with various types of leprosy. An abnormal tear film BKUT (47.2%) was observed to be much more informative in the present series than the study of schirmer's test alone (25.4%). In patients with lagophthalmos an abnormal tear film BKUT (70%) was higher as compared to an abnormal schirmer's test (40%); while in cases of lagophthalmos with ectropion an abnormal schirmer's test was seen less frequently (26.8%) than in cases of lagophthalmos without ectropion (58.3%). This implied an increase in the aqueous content of the tear film in cases of lagophthalmos with ectropion on the basis of an associated chronic conjunctivitis. Lagophthalmos and ectropion have been identified as additional factors contributing to corneal morbidity. There was a statistically significant difference in the tear film abnormality in different types of leprosy, the maximal difference being in the lepromatous variety.

Humans↗

Argon laser iridotomy in angle closure glaucoma.

Argon laser iridotomy was successfully performed in 30 eyes of glaucoma patients. A modified two stage procedure has been described to achieve a successful iridotomy in pigmented eyes. At the chosen site of laser iridotomy, partial thickness burns were applied in the first stage followed by a penetrating burns in the second stage. This minimised the complications associated with laser iridotomy and decreased the incidence of subsequent closure. At the end of 6 months follow up the success rate was 93.3 percent.

Adult↗

Response of laboratory-adapted human hookworm and other nematodes to ivermectin.

The activity of ivermectin was examined in Necator americanus, a human hookworm, adapted to the laboratory hamster. A dose of 30 mg kg-1 X 1 or 10 mg kg-1 X 2 was required for complete clearance of pre-adult N. americanus; however, hamsters carrying adult N. americanus were completely cured of infection by doses of 15 mg kg-1 or 7.5 mg kg-1 X 2. The doses of ivermectin required for complete elimination of N. americanus were much higher than those reported for other intestinal nematodes. The probable reasons for these higher doses are discussed. Tests were also carried out with other rodent parasites, namely Nematospiroides dubius, Strongyloides ratti and Trichuris muris. Doses as low as 0.3 mg kg-1 X 1 completely eliminated adult N. dubius from mice, whereas++ S. ratti needed a repeated dose (0.3 mg kg-1 X 2). None of the mice was cured of T. muris infection even at doses of 10 mg kg-1 X 2, although some degree of cure was apparent at the toxic dose. It thus appears that ivermectin is in no way superior in its activity against N. americanus and T. muris than the existing anthelmintics.

Animals↗

Temperature Dependence of Photosynthetic Activities in Wheat Seedlings Grown in the Presence of BASF 13.338 (4-Chloro-5-Dimethylamino-2-Phenyl-3(2H)Pyridazinone).

When Triticum vulgare cv HD 2189 seedlings were grown in the presence of 125 micromolar BASF 13.338 (4-chloro-5-dimethylamino-2-phenyl-3(2H)pyridazinone), the rate of electron transport (H(2)O --> methyl viologen) in chloroplast thylakoids isolated from the treated seedlings was higher (by 50%) as compared to the control at assay temperatures above 30 degrees C. Below 30 degrees C, however, the rate with the treated seedlings was lower than the control rate. The temperature dependence of the rate of photosystem I electron transport (2-6-dichlorophenol indophenol-reduced --> methyl viologen) in the treated system was similar to that in the control. At high temperatures (>30 degrees C), with diphenyl carabazide as electron donor, the rates of electron transfer (diphenyl carbazide --> methyl viologen) were similar in the treated and in the control thylakoids. Direct addition of BASF 13.338 to the assay mixture for the measurement of rate of electron transport (H(2)O --> methyl viologen) in the thylakoids isolated from the control plants did not cause any change in the temperature dependence of photosynthetic electron transport. These results suggested that the donor side of photosystem II became tolerant to heat in the treated plants. Chlorophyll a fluorescence emission was monitored continuously in the leaves of control and BASF 13.338 treated wheat seedlings during continuous increase in temperature (1 degrees C per minute). The fluorescence-temperature profile showed a decrease in the fluorescence yield above 55 degrees C; this decrease was biphasic in the control and monophasic in the treated plants.

Journal Article↗

Response of preadult Necator americanus to some known anthelmintics in hamsters.

Hamsters infected with laboratory-adapted preadult Necator americanus were dosed with 6 reference anthelmintics. Their efficacy was measured in terms of percentage cure of infected animals as well as percentage worm reduction following treatment. Mebendazole and pyrantel were equally effective in this system. Other anthelmintics, including anti-hookworm compound, bephenium hydroxynaphthoate, were less effective. The comparative results revealed that the N. americanus model is sensitive and reliable for identifying and characterizing new anti-parasite preparations.

Administration, Oral↗

Post-illumination kinetics of cytochrome f reduction in chloroplast thylakoid in the presence of dibromothymoquinone.

Addition of dibromothymoquinone (DBMIB) to isolated chloroplast thylakoids reduces cytochrome f in the dark. Reduced cytochrome f is oxidised when the thylakoids are illuminated, and is re-reduced in the subsequent darkness. The rate of re-reduction in the dark is faster after red (650 nm) illumination than after far red (713 nm) illumination. In the presence of DCMU or upon heat treatment or at high (greater than 10 microM) concentration of DBMIB the rate of dark reduction after red illumination becomes slower and equal to that after far red illumination, suggesting that photosystem II electron transfer at least upto plastoquinone facilitates DBMIB-mediated reduction of cytochrome f in the thylakoids.

Chloroplasts↗

Necator americanus and Ancylostoma ceylanicum: development of protocols for dual infection in hamsters.

Two-day-old baby hamsters were infected initially with the infective larvae of hamster-adapted human hookworm, Necator americanus (NaL3). After a specified period they were again infected orally with infective larvae of Ancylostoma ceylanicum (AcL3). Three weeks after the second infection they were killed and the establishment of N. americanus and A. ceylanicum was assessed. The effect of different infection levels and exposure period of N. americanus on the concurrent establishment of A. ceylanicum was also examined. An infection with 50 NaL3 percutaneously, and 3 weeks later, a second infection with 50 AcL3 orally has produced reasonably equal number of hookworms (no statistical difference in the burden of N. americanus and A. ceylanicum) in the intestine of hamsters. Thus this protocol of dual infection was found suitable to develop two species of hookworms in hamsters for anthelmintic screening.

Ancylostoma↗

Site of resistance to Necator americanus in hamsters.

Resistance to the development of human hookworm, Necator americanus was examined in 3- to 6-week-old young adult hamsters. Only 3% of N. americanus infective third stage larvae (NaL3) reached maturity in the intestines of young adults as opposed to as many as 60% in 2-day-old baby hamsters. This seemingly effective resistance prevailing in young adults was investigated in some detail. The skin, the first site of contact for the invading NaL3, was bypassed during the infection process. Completely in vitro exsheathed NaL3 (ExNaL3) were used, and young adult hamsters were infected parenterally, by-passing the skin. Even after exsheathing the larvae artificially before infection and by-passing the skin, no improvement was seen in the development of N. americanus in the intestines of young adults. Higher infection doses also did not increase the worm burden. Some of the factors limiting the development of parasites in young adults were examined. N. americanus were monitored in lungs and intestines during various intervals after infection. Similar parasite burdens were apparent in lungs of baby as well as young adult hamsters. In the intestines, a significantly lower burden of N. americanus was seen during various intervals in young adults compared to the baby hamsters. Moreover, N. americanus were expelled soon after reaching the intestine. This comparative monitoring revealed the intestine as the seat of resistance against the establishment of N. americanus in young adult hamsters.

Age Factors↗