Search PubMed⌕ Search

Biomedical subjects

P Nath

Publications and source records attributed to P Nath.

At least 73 records · Page 4Linked to original sources
PubMed1985

Recombinant DNA techniques: storage and screening of cDNA libraries with large numbers of individual colonies from initial transformations.

A typical cDNA library with a large number of initial transformants, plated in soft agarose, can be stored and shipped in 12% glycerol at -70 degrees C. To prepare the library for storage, the soft agarose layer is made into a paste and the agarose is removed by Sephadex G-25 filtration. This method of cDNA library storage does not alter the relative representation of the plasmids carried in the library. To achieve a very uniform distribution of colonies at high colony density, an aliquot of the cDNA library is diluted to 3000 to 10,000 colonies/ml. One milliliter of this suspension is evenly distributed on a nitrocellulose filter on an agar plate and air-dried. Filter copies are made and screened by published methods.

Cloning, Molecular↗
PubMed1983

Biochemical correlates of airway hyperreactivity in guinea pigs: role of lysophosphatidyl choline.

To elucidate the biochemical basis of airway hyperreactivity, we studied the relationships between in vivo airway sensitivity of guinea pigs to histamine and their tracheal beta-adrenergic binding sites, Ca++- and (Na+-K+)-ATPase activities, and composition of phospholipids. The relationships between tracheal and plasma phospholipids were also examined. beta-Adrenergic receptor binding with 3H-dihydroalprenolol in tracheal tissue showed an inverse relationship with in vivo airway sensitivity to histamine. Among the phospholipids, tracheal phosphatidyl ethanolamine content varied inversely with in vivo airway sensitivity, whereas tracheal and plasma lysophosphatidyl choline contents showed a direct correlation with airway sensitivity. A significant direct correlation was also observed between tracheal and plasma lysophosphatidyl choline levels. Both Ca++-ATPase and (Na+-K+)-ATPase activities increased with increasing airway sensitivity. These enzymes showed inverse correlations with phosphatidyl ethanolamine content and direct correlations with lysophosphatidyl choline content. Our data suggest that increased lysophosphatidyl choline may cause various biochemical changes associated with airway hyperreactivity.

Animals↗
PubMed1982

Ultrastructural changes in skeletal muscles in dengue virus-infected mice.

Dengue type 2 virus was inoculated intracerebrally in 20 adult swiss albino mice. Thigh muscles were removed after 24 h 3, 5 and 7 days after virus inoculation. Electron microscopic studies of the striated muscles show destruction of myofibrils, rarification of the sarcoplasmic reticulum network and changes in the mitochondria. Aggregates of electron-dense material as well as glycogen particles were also seen in the cytoplasm.

Animals↗
PubMed1982

Circadian meal timing in relation to lighting schedule optimizes catfish body weight gain.

Two groups of 4- to 5-month-old catfish, Heteropneustes fossilis, were studied 2 years apart, in each case after standardization in light for 12 hours, alternating with darkness for 12 hours. The two studies involved 5 groups of 10 catfish each and 10 groups of 17 catfish each, respectively. In each study some fish were allowed access to food only during certain times in the circadian cycle: early dark, late dark, early light and late light for 45 or 50 days. On the average, in both studies, the catfish on restricted feeding schedules gained in body weight but more so when fed at certain times in the circadian cycle as compared to others. A circadian rhythm in weight response was demonstrated by a zero-amplitude test associated with the fit of a 24-hour cosine curve to the data (P less than 0.03). The acrophase (time of high values) for body weight gain occurred consistently either near the middle or in the second half of the daily dark span. That is, body weight gain in the presumably dark-active catfish seems to be maximal when food is made available in the middle or later part of the daily dark span. In catfish, as in human beings and mice, the timing of food intake can serve to optimize the utilization of ingested calories, by mechanisms yet to be elucidated.

Animals↗