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Biomedical subjects

S Krishnan

Publications and source records attributed to S Krishnan.

At least 127 records · Page 7Linked to original sources

Recovery of slow and fast muscles following nerve injury during early post-natal development in the rat.

1. The sciatic nerve was crushed in 5-6-day-old rats and the recovery of function of slow and fast muscles was studied. The first signs of recovery of function were seen 10-12 days after the operation. 2. Maximal tetanic tension developed by the reinnervated muscles was recorded and taken as an indication of their recovery. Two months after nerve crush, slow soleus muscles developed only slightly less tension than the control unoperated soleus muscles. The reinnervated fast muscles tibialis anterior (t.a.) and extensor digitorum longus (e.d.l.) developed only about 50% of the tension of the unoperated controls. 3. The fast muscles never recovered, remaining weaker and smaller throughout the animals' life. 4. The number of muscle fibres in the reinnervated fast muscles was substantially reduced and their fibre composition altered in that they contained mainly muscle fibres with high levels of oxidative enzymes. 5. The reinnervated fast muscles became much more fatigue resistant than the unoperated controls. 6. The possibility that these changes are due to motoneurone death was examined. The motoneurones innervating the fast muscles were labelled by retrograde transport of HRP. No significant reduction in the number of motoneurones innervating the operated muscles was found. 7. These results show that nerve injury during early post-natal life causes permanent changes in fast muscles that are not caused by motoneurone death.

Animals↗

Immunoglobulins in serum and duodenal juice and peripheral blood lymphocyte subpopulations in patients with giardiasis.

Forty eight patients with symptomatic giardiasis and 22 apparently healthy matched controls without Giardia lamblia were studied with respect to the following variables--immunoglobulins (Igs) G, A and M in serum, IgA in duodenal juice and T and B in lymphocyte sub-populations. There were no differences observed between the two groups with regard to any of these variables except for serum IgG which was found to be higher in patients. It was concluded that endemic giardiasis has no immunodeficient basis and has nothing in common with the association of giardiasis, mal absorption and immunodeficiency reported from the West. Further, no change in these variables was observed when the tests were repeated after cure.

Adolescent↗

Experimental horizontal transmission of feline leukemia viruses of subgroups A, B, and C.

Experiments were conducted with cats in metal cages inside plastic isolators to determine whether feline leukemia virus (FeLV) of the three known antigenic subgroups (A, B, and C) is transmitted horizontally from infected cats to normal "contact" cats. Blood smears collected at weekly intervals were examined by the fixed-cell, indirect immunofluorescence test for FeLV internal p30 to follow the spread of infection from inoculated cat to contact cats. These studies established that viruses of all three subgroups are transmitted horizontally among kittens and adults with slightly varying degrees of speed. Virus was reisolated from one horizontally infected contact cat of each group, and its envelope antigenic type was the same as that originally inoculated into one cat of the same group. After the cats acquired the infection, they became chronic carriers of virus (viremic) during the observation period of 9 or 11 weeks post inoculation.

Animals↗

Hypogammaglobulinaemic sprue in tropics: Report of an Indian patient.

Acquired hypogammaglobulinaemia is a rare disease and has not been reported from tropical regions before. A fourteen year old boy, who had symptoms of intestinal malabsorption since the age of seven years, was investigated and found to be suffering from severe hypogammaglobulinaemic sprue which ended fatally. The problems in diagnosis and management of this rare disorder have been highlighted.

Adolescent↗

Effect of vitamin A and undernutrition on the susceptibility of rodents to a malarial parasite Plasmodium berghei.

The ability of vitamin A deficient rats to resist infection with P. berghei was investigated. When 10 X 10(6) erythrocytes bearing the parasite/100 g body weight were given to the vitamin A protein energy undernourished rats, parasitemia developed in these animals at a faster pace than the controls. A high number (60% to 95%) of red blood cells (RBC) carrying the parasite were noticeable within 6 to 7 days after infection, at which time most animals in this group died. The pair-fed controls (protein-energy undernourished but supplemented with vitamin A) fared perceptibly better with an equivalent load of infection. Control ad libitum fed littermates were able to restrict the infection and neither high parasitemia nor death was noted in this group. Oral supplements of retinyl acetate to vitamin A deficient rats enabled the animals to recover from infection. A subclinical dose of 500 parasitized RBC given at an early stage of the vitamin A deficiency precipitated the deficiency symptoms at a faster rate and led to the development of higher order of parasitemia in these rats beginning from the 10th day after infection as compared to pair fed controls. The yield of glass adhering cells obtainable from peritoneal exudates was low in deficient rats. In vitro experiments further suggest a decrease in the capacity of the glass adhering peritoneal exudate cells in vitamin A deficient mice to clear the infection. This capacity was improved by addition of non glass adhering cells from sensitized control mice.

Animals↗