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H M Murphy

Publications and source records attributed to H M Murphy.

At least 37 records · Page 2Linked to original sources
PubMed1975

RNA of replication-defective strains of Rous sarcoma virus.

The RNA of a replication-defective (rd) mutant, isolated from stocks of nondefective (nd) Schmidt-Ruppin Rous sarcoma virus of subgroup A (SR-A) and termed SR-N8, was compared to the RNAs of SR-A, of a transformation-defective derivative of SR-A (td SR-A) and of rd Bryan Rous sarcoma virus, RSV (minus). The molecular mass of the 30-40S species of SR-N8 RNA was estimated to be 21% (congruent to 7.5 to 8 times 10-5 daltons) smaller than that of SR-A by (i) electrophoresis in polyacrylamide gels and (ii) analyses of RNA complexity based on RNase T1-resistant oligonucleotides. ST-N8 shares probably all (=14) of its large RNase T1-resistant oligonucleotides with the RNA of SR-A as judged from the chromatographic distribution and the RNase A-resistant fragments obtained from RNase T1-resistant oligonucleotides. However, SR-N8 RNA lacked six large oligonucleotides which were present in the RNAs of SR-A and td SR-A. Conversely, the RNAs of SR-A, and of SR-N8 contained two oligonucleotides not found in td SR-A. The RNA of SR-N8 was found to differ from that of RSV (minus) in its electrophoretic mobility and its fingerprint pattern. It is concluded that the RNA of SR-N8 was generated by a deletion of SR-A. The extent of this deletion is compatible with the notion that the genetic information for the large viral envelope glycoprotein (molecular mass = 70,000-85,000 daltons) has been lost from the RNA of SR-A to yield SR-N8 RNA. From a comparison of td and rd deletion mutants, it appears that loss of different functions corresponds to the absence of different oligonucleotides in their RNA.

Avian Sarcoma Viruses↗
PubMedDate not supplied

Effects of TRH injection on hippocampal-hypothalamic-pituitary-thyroid interactions.

The first experiment was conducted in an attempt to ascertain the effects of hippocampal lesions on plasma levels of total T4, total T3, free T4, and TSH. Animals with hippocampal lesions had significantly lower levels of total T4, free T4 and TSH than cortical control and normal animals. There were no significant differences in total T3 among the three groups. Since these results indicated that animals with hippocampal lesions manifested a dysfunction in the hypothalamic-pituitary-thyroid axis, a second experiment was undertaken to determine the site of mediation. A TRH injection test demonstrated that the dysfunction occurs at the level of the hypothalamus. It is hypothesized that in the normal animal the hippocampus exerts a facilitating effect on the hypothalamic-pituitary-thyroid axis.

Animals↗
PubMedDate not supplied

Effects of vasopressin replacement during food-restriction stress.

The effects of subcutaneous injections of vasopressin in vasopressin-deficient (Brattleboro or DI) rats were observed during nonstress (habituation) and stress (food-restriction) conditions as compared to other rats. Four groups of animals were employed: 1) Long-Evans (LE) rats that were food restricted with no injections (normal control animals), 2) DI rats that were food restricted with no injections, 3) DI rats injected with vasopressin, and 4) DI rats injected with peanut oil (vehicle). The parameters studied were: body weight, food intake, water intake, and gastric ulcer formation. With respect to body weight, water intake, and ulcer formation, two sets of animals emerged. The vasopressin-injected DI rats resembled the LE control rats, whereas the peanut oil-injected DI rats were similar to the DI rats with no injections. The former set of animals showed a higher body weight, reduced water intake, and fewer gastric ulcers than the latter set of animals. Thus the vasopressin-injected DI rats and the LE control rats could cope with the stress of food restriction, but the peanut oil-injected DI rats and the DI rats with no injections could not.

Animals↗
PubMedDate not supplied

Vasopressin deficiency and the modulation of consummatory behavior.

This study examined patterns of consummatory behavior in normal and vasopressin-deficient rats under ad lib and food-restricted conditions. Differing patterns of intake of food, water, sucrose, and saccharin were found in the two groups. During the ad lib period, the normal rats gained more weight and ate significantly more food than vasopressin-deficient rats. The vasopressin-deficient animals consumed significantly more sucrose than normal animals during this period. No significant differences in body weight, food intake, sucrose intake, or saccharin intake were noted during the food-restricted period between the two groups. During the food-restricted condition the normal animals showed a cyclic pattern of food, sucrose, and saccharin intake. This cyclic pattern of intake was absent in vasopressin-deficient animals. A vasopressin-serotonin interaction is hypothesized as a possible mechanism producing the differences in the two strains of animals. In addition, the data support the position that food consumption is regulated primarily by caloric and/or nutritional factors.

Animals↗
PubMedDate not supplied

Vasopressin, corticosterone levels, and gastric ulcers during food-restriction stress.

Corticosterone levels and ulcers were compared in vasopressin-containing (LE) and vasopressin-deficient (DI) rats under ad lib and food-restricted conditions. In the ad lib situation, DI and LE rats had similar corticosterone levels and no ulcers. After 1 day of food restriction, the corticosterone levels were elevated in DI and LE rats, with a significantly higher level in LE rats. No ulcers were present in either strain. After 2 days of food restriction, the corticosterone levels were similar in DI and LE rats. The level in DI rats was comparable to that of the preceding day, but the level in LE animals dropped significantly from the previous day. Significant ulceration was evident in DI rats, but absent in LE rats. Following 3 days of food restriction, the corticosterone level in LE rats had returned to the ad lib level, whereas, for DI rats, an elevated level was maintained. There were no ulcers in LE rats, but they were present in DI rats. Thus LE and DI rats responded differently to the stress of food restriction. The mechanism underlying the response is most likely related to changes in the hypothalamic-pituitary-adrenocortical axis and its reaction to stress.

Adaptation, Physiological↗
PubMedDate not supplied

Modulatory effects of vasopressin on glucose and protein metabolism during food-restriction stress.

Plasma levels of glucose and urea nitrogen were compared in vasopressin-containing (LE) and vasopressin-deficient (DI) rats under ad lib and food-restricted conditions. In the ad lib situation, DI and LE rats had similar levels of glucose and urea nitrogen. Variations in this pattern were observed under food-restricted conditions. The DI animals exhibited lower levels of glucose and higher levels of urea nitrogen than their LE counterparts. During food restriction, the glucose levels of LE animals were not different from that observed under ad lib conditions. A significant decrease, however, was observed in the glucose levels in DI animals during food restriction. Urea nitrogen levels in LE animals decreased during food restriction as compared to the ad lib situation, whereas urea nitrogen levels of DI animals increased during food restriction. These observations indicate that vasopressin has a modulatory role on glucose and protein metabolism during the stress of food restriction.

Animals↗