Search PubMed⌕ Search

Biomedical subjects

S Nadkarni

Publications and source records attributed to S Nadkarni.

22 records · Page 2Linked to original sources
PubMed1977

Modification of the radiosensitivity of barley seed by post-treatment with caffein. IV. Effect of the moisture content of seed and storage temperature after irradiation.

The oxygen-dependent damage which develops in barley seeds with approximately 7-8 per cent moisture content disappears after post-irradiation storage in vacuo for 48 hours at 40 degrees C and for 24 hours at 50 degrees C. When the diration of storage at 40 degrees C is extended to 384 hours, oxygen-independent damage becomes potentiated. There is oxygen-dependent damage in seeds of approximately 13.3 per cent moisture content and after the seeds have been stored in vacuo at 50 degrees C, the oxygen-dependent damage begins to increase by 168 hours, and it is very significantly potentiated by 192 hours. Under these circumstances, caffeine acts as a radioprotector only as long as the precursors of oxic damage are present in the seeds. Once these sites are lost, caffeine acts only as a radiosensitizer. The oxygen-independent damage which increases with storage at high temperature is further potentiated by caffeine.

Caffeine↗
PubMed1975

Modification of the radiosensitivity of barley seed by post-treatment with caffeine. Kinetics of decay of caffeine-reactive oxygen-sensitive sites.

In dry barley seeds (3-1 per cent moisture content), the maximal level of oxic damage (class III damage) is reached within the first 40 min of post-hydration in oxygenated water at 5 +/- 1 degrees C. The decay of the gamma-ray-induced oxygen-sensitive sites requires, however, about 120 min. The mechanisms leading to partial protection against the class III damage are initiated when caffeine is present during the first 30 min of oxygenated post-hydration. If added after 30 min of oxygenated hydration, caffeine has no protective action. For the potentiation of an oxygen-independent component of damage, caffeine has to be present during the first 240 min of oxygen-free hydration. These observations involving a physiologically inert system raise questions regarding physico-chemical vis-a-vis biochemical mechanisms of caffeine effect on irradiated systems and these have been briefly discussed.

Caffeine↗
PubMedDate not supplied

Relationship between plasmin-trypsin-inhibitory and sialyltransferase activities.

Previously we have shown that the measurable soluble sialyltransferase (STase) activity released into the medium during the incubation of rat jejunal slices was dependent upon the presence of a heparin-binding fraction (HBF) from heat-inactivated serum or a trypsin-binding protein (TBP) isolated from HBF. Both HBF and TBP were able to inhibit trypsin and plasmin. The measurement of galactosyltransferase (GTase) activity which was also released in incubations was not dependent on HBF or TBP. The present study is directed towards further exploring the relationship between STase activity and protease inhibitory activity. Heat-inactivated serum from turpentine-treated rats (HTS), had higher plasmin-trypsin-inhibitory (HTS) activities compared to heat-inactivated serum from control rats (HCS). When HTS was used to supplement jejunal incubations, there was a 25-40% increase in the measurable STase activity in the incubation medium compared to similar incubations carried out in buffer alone. In contrast, with HCS the increase was 10-15%. During incubations with hepatocytes, STase activity detected in the incubation medium was increased with the incubation buffer was supplemented with HTS compared to incubations supplemented with HCS. Serum antiproteolytic activity was higher in turpentine rats compared to controls. Incubation of serum at 37 degrees C led to a progressive decrease in plasmin-trypsin-inhibitory and STase activities. TBP a plasmin and trypsin inhibitor was able to prevent the decrease in STase activity. Overall, serum STase activity was higher in the turpentine treated rats. In contrast, GTPase activity in serum as well as that detected in the medium during jejunal and hepatocyte incubations was not dependent on protease inhibitory activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗