Biomedical subjects

G Y Ma

Publications and source records attributed to G Y Ma.

22 records · Page 2Linked to original sources

PubMed1975

Metabolic actions of vasopressin, glucagon and adrenalin in the intact rat.

Metabolic effects of vasopressin, glucagan and adrenalin were compared, in intact rats, especially in regard to time courses of effects. Hyperglycaemia was transient in response to vasopressin, prolonged following adrenalin, and, suprisingly, was not discernible after glucagon, except in response to a very large dose. Vasopressin decreased and adrenalin increased, the plasma free fatty acid concentration; both hormones decreased the triacylglycerol level. Muscle glycogen concentrations, measured in heart, diaphragm and skeletal muscle, exhibited small changes, with complex time courses, following hormone administration. Vasopressin brought about a rapid but transient activation of heaptic glycogen phosphorylase which resembled that due to adrenalin. The activation by glucagon of phosphorylase was greater and more prolonged, despite the absence of hyperglycaemia. In response to vasopressin, there was in increase in plasma insulin. Incorporation of 14C from [14C]glucose into glycogen or fatty acids was not influenced by vasopressin. Taken together, these results may be explained by rapid metabolic action of vasopressin on hepatic glycogenolysis, whereas adrenalin has multiple prolonged actions.

Adipose Tissue↗

PubMed1975

Ribosomal RNA turnover and the level of ribonuclease activity in the liver of the pregnant rat.

Studies were undertaken on the turnover of ribosomal RNA and on ribonuclease activity in the liver of the pregnant rat in an attempt to explain the accumulation of liver RNA which occurs during the latter half of pregnancy. Between the 15th and 20th day of gestation the rate constant of degradation, biological half-life and daily rate of synthesis of ribosomal RNA were calculated to be 0.0887, 7.81 days and 6.21 mg per liver per 100g body weight respectively. Corresponding values in non-pregnant rats were 0.123, 5.68 days and 3.47 mg per liver per 100g body weight. The increase in RNA was therefore associated with an increase in its rate of synthesis and a decrease in its rate of breakdown. From the 14th day of pregnancy there was a decrease in alkaline ribonuclease activity and a marked increase in the level of alkaline ribonuclease inhibitor. The activity of acid ribonuclease was found to increase and that of acid phosphatase to decrease during this period.

Acid Phosphatase↗

PubMed1975

Inhibition of fatty acid synthesis and stimulation of glycogen breakdown by vasopressin in the perfused mouse liver.

1. Vasopressin (anti-diuretic hormone, [8-arginine]vasopressin) inhibited the synthesis de novo of fatty acids (measured with (3)H(2)O and U-(14)C-labelled lactate or U-(14)C-labelled glucose) and stimulated glycogen breakdown in the perfused liver of fed mice. 2. The concentration dependence of these effects (range 200-1000muunits/ml, i.e. 0.5-2.5ng/ml) resembled that for the action on glycogen breakdown which was previously reported for rat liver. 3. The appearance of newly synthesized fatty acids in both phospholipids and triglycerides was inhibited by vasopressin, whereas synthesis of cholesterol was less affected. 4. Inhibition of hepatic lipogenesis by vasopressin is the most potent short-term hormonal action on this process yet reported. Aspects of the effect are discussed, including the lack of a role for cyclic AMP, and a possible link with vasopressin action on glycogen metabolism.

Animals↗

PubMedDate not supplied

Continuous hyperthermic peritoneal perfusion with cisplatin for the treatment of peritoneal mesothelioma.

PURPOSE: Peritoneal mesothelioma remains a difficult therapeutic challenge. Aggressive debulking combined with continuous hyperthermic peritoneal perfusion (CHPP) using cisplatin (CDDP) is a novel strategy for the treatment of peritoneal mesothelioma, allowing high regional delivery of chemotherapeutics and hyperthermia while minimizing systemic toxicity. PATIENTS AND METHODS: From June 1993 to May 1996, 10 patients with peritoneal mesothelioma (six men, four women; mean age 40 years, range 15-57) underwent tumor debulking followed by a 90-minute CHPP. CHPP parameters included mean initial CDDP of 120 micrograms/mL (range 81-166), perfusate volume 5.2 L (range 4-7), flow 1.5 L/min, intraperitoneal temperature at three locations-41.5 degrees C, 40.5 degrees C, 41.1 degrees C, and core temperature 38.4 degrees C (range 37.2 degrees C-39.5 degrees C). Nine of 10 patients had malignant peritoneal mesothelioma, eight with associated ascites, while the tenth had a symptomatic, multiply recurrent benign peritoneal mesothelioma. Nine of 10 patients were optimally debulked. Pharmacokinetics were performed on blood and perfusate samples on nine patients; CDDP levels were quantitated by atomic absorption spectroscopy. RESULTS: Total perfusate cisplatin AUC was a mean of 21-fold higher (range 2- to 116-fold) than total serum cisplatin AUC, and serum CDDP behaved similarly to systemically administered CDDP. Median follow-up after CHPP is 10 months (range 2-32), with no treatment-related mortality. In eight optimally debulked patients there is no evidence of recurrent disease clinically or by CT or MRI. Seven patients with symptomatic ascites have been completely palliated. CONCLUSIONS: CHPP with CDDP is well tolerated with no significant regional toxicity. Because favorable CDDP pharmacokinetics suggest the potential for enhanced CDDP tumoricidal effect during CHPP, tumor debulking and CHPP may represent an effective strategy for the treatment of peritoneal mesothelioma.

Adolescent↗