Derepression of sporulation and synthesis of mycobacillin and dipicolinic acid by guanosine 3':5'-cyclic monophosphate under conditions of glucose repression in Bacillus subtilis

Dibutyryl cyclic GMP, but not dibutyryl cyclic AMP, derepresses sporulation and synthesis of mycobacillin and dipicolinic acid under conditions of glucose repression in Bacillus subtilis strain B34. Neither of these compounds appears to affect sporulation and synthesis of mycobacillin and dipicolinic acid in this strain under normal physiological conditions. Mutants insensitive to glucose repression were indifferent to the addition of either of the nucleotides both in the presence and in the absence of glucose. A role for dibutyryl cyclic GMP in annulling the repressing effect of glucose on sporulation and on synthesis of mycobacillin and dipicolinic acid is thus indicated.

Effect of changes in the osmolarity of the growth medium on Vibrio cholerae cells

The rate and extent of lysis of Vibrio cholerae cells under nongrowing conditions were dependent on the osmolarity of the growth medium. Gross alterations in cellular morphology were observed when V. cholerae cells were grown in media of high and low osmolarity. The rate of lysis of V. cholerae cells under nongrowing conditions increased after treatment with chloramphenicol. Chloramphenicol-treated V. cholerae 569B cells showed formation of sphaeroplast-like bodies in medium of high osmolarity, but not in low osmolarity. Changes in the osmolarity of the growth medium also regulated the expression of the outer membrane proteins. This regulation was abolished if V. cholerae cells were grown in Pi-depleted medium. Analysis of the lytic behavior and composition of outer membrane proteins of an osmotically fragile mutant strain revealed a similar dependence on the osmolarity of the growth medium.

The effect of medroxyprogesterone acetate on the hepatic drug-metabolizing enzymes in normal and protein-deficient female rats

Effect of depot medroxyprogesterone acetate on the hepatic drug-metabolizing enzymes was studied in female protein-deficient and normal pair-fed rats. Treatment with this drug did not cause any change in organ weight, microsomal protein, and soluble protein yield per gram of tissue in both groups. MPA administration resulted in significant increases in the content of cytochrome P-450 and b5, and activities of benzo[a]pyrene hydroxylase, UDP-glucuronosyltransferase, and NADPH-Cyt c reductase in both pair-fed control and protein-deficient rats. However, the content of glutathione and activity of glutathione-S-transferase were not affected appreciably. The present study suggests that MPA treatment induces drug-metabolizing enzymes in liver to almost the same extent in both protein-deficient and normal pair-fed rats.

Modification of aflatoxin B1-induced changes in certain mitochondrial enzymes and lipids by medroxyprogesterone acetate

The effect of a single dose of 5 mg/kg body weight of aflatoxin B1 on rat liver mitochondrial enzymes, succinate dehydrogenase (SDH) and Mg++ adenosine triphosphatase (Mg++-ATPase) and on certain lipids were studies at various intervals of time from 3 to 24 hours. A significant decrease in the specific activity of SDH was observed after 6, 12, 18 and 24 hr treatment. The Mg++-ATPase activity remained unaffected up to 12 hr but appreciably decreased after, 18 and 24 hr of the treatment. The level of phospholipids and cholesterol were not altered after 3, 6 and 12 hr treatment, thereafter (18 and 24 hr) an increase was observed in both the lipids following the aflatoxin treatment. Medroxyprogesterone acetate (MPA) did not cause any alteration in the specific activities of these enzymes as well as levels of cholesterol and phospholipids. The treatment with MPA caused significant increase in contents of cytochromes P-450, b5 and activities of Arylhydrocarbon hydroxylase (AHH), UDP-glucuronyl transferase (UDP-GT) and NADPH-cytochrome C-reductase of hepatic microsomes. It was observed that pretreatment with medroxyprogesterone acetate (MPA) could significantly minimuze the depression caused in mitochondrial SDH and Mg++-ATPase activities by aflatoxin B1.

Effects of 17 beta-estradiol and progesterone on intestinal digestive and absorptive functions in ovariectomized rats

The effects of low and high doses of 17 beta-estradiol and progesterone for 2 weeks on intestinal digestive and absorptive functions have been investigated in ovariectomized rats. The uptake of glucose was significantly enhanced following ovariectomy and administration of hormones restored the level of glucose uptake to that observed in sham-operated animals. Neither, the uptake of L-leucine nor calcium was affected after ovariectomy and treatment with the hormones. The activity of alkaline phosphatase (AP) of ileum was significantly elevated with the low and high doses of 17 beta-estradiol but in jejunum only at high doses. Progesterone alone did not alter AP activity but the combination of this hormone and 17 beta-estradiol significantly enhanced the jejunal and ileal AP activities. It seems that activity of AP is mainly under the control of 17 beta-estradiol. The activity of ileal disaccharidases and leucine aminopeptidase were enhanced at high doses of 17 beta-estradiol alone or in combination with progesterone whereas in the jejunum only AP activity was increased significantly. The present study indicates that 17 beta-estradiol plays an important role in regulating the activities of intestinal digestive enzymes and it is the ileal enzymes which are more prone to its action.

Effect of a steroidal oral contraceptive on intestinal absorptive functions in proteins deficient rat

The effects of steroidal oral contraceptive norethynodrel plus ethinylestradiol-3-methyl ether (SOC) at a daily dose of 5 mg: 0.06 mg per kg body weight for 28 days on intestinal absorptive functions have been investigated in protein-deficient female albino rats. The administration of this contraceptive caused significant increase in glucose and amino acids uptake but had no effect on calcium and zinc uptake in pair-fed as well as in protein-deficient rat. Further studies carried out on glucose transport system showed that the transport of sodium-dependent glucose was significantly enhanced while that of sodium-independent glucose remained unaltered in drug-treated animals. Kinetic studies of glucose transport in the presence of sodium ions revealed that SOC treatment affected the rate of uptake of glucose by elevating Vmax, but the apparent Kt value remained the same in treated and untreated animals.

Aggravation of experimental atherosclerosis in vasectomized, cholesterol-fed rabbits

Rabbits were fed a stock or atherogenic diet for a period of fourteen months. Half of each group of rabbits was bilaterally vasectomized while the other half underwent sham vasectomy. The level of plasma cholesterol was significantly elevated following vasectomy in stock diet-fed rabbits. Atherogenic diet feeding caused marked elevation of plasma cholesterol in both vasectomized as well as sham-vasectomized animals. At the termination of the experiments, aortic cholesterol in stock diet-fed vasectomized rabbits remained unchanged, but this was increased in both vasectomized and sham-vasectomized atherogenic diet-fed animals. Aortic sudanophilia, atherosclerotic plaque size and coronary atherosclerosis index were significantly increased in vasectomized atherogenic diet-fed rabbits as compared to their controls. In stock diet-fed vasectomized rabbits no macroscopic or microscopic lesions were seen even in the presence of mild hypercholesterolaemia.

Effect of short-term and long-term treatment with a steroidal oral contraceptive on the intestinal absorption of nutrients in vitro in female rats

The effect of steroidal oral contraceptive (SOC), comprising megestrol acetate (5 mg/kg body weight) plus ethinyl estradiol (0.05 mg/kg body weight), administered daily by stomach tube for 5, 15, 30 and 90 days, on the intestinal uptake of nutrients such as glucose, amino acids and calcium has been investigated in vitro in female rats. The administration of SOC for 5 days did not affect the uptake of nutrients, but treatment for 15, 30 and 90 days led to a progressive and significant increase in the uptake of glucose and amino acids. The calcium uptake was increased in the groups treated for 5 and 15 days, but decreased after 30 and 90 days of treatment. Kinetic studies done on glucose uptake indicated that the steroid contraceptive might be inducing the transport carrier protein of this nutrient, as elevation in Vmax was observed in the group treated for 30 days. There was no change in brush border membrane phospholipid and cholesterol contents after 30 and 90 days of treatment, but a significant increase in phospholipid after 5 and 15 days of treatment was observed. This study suggests that SOC treatment significantly altered the intestinal absorptive functions and the effect appears to be on the carrier-mediated transport of glucose.

Effect of medroxyprogesterone acetate on the intestinal absorptive functions in protein-deficient rat

Effect of Medroxyprogesterone acetate (MPA) at a dose level of 35mg/Kg body weight per week for four weeks on the intestinal uptake of nutrients viz glucose, amino acids, (alanine and leucine), calcium and zinc has been investigated in protein-deficient female rats. The administration of MPA was found to enhance significantly the uptake of glucose and amino acids in both the pair-fed and the protein-deficient rats. In contrast, calcium uptake was depressed as a result of treatment with the drug as well as protein-deficiency. The uptake of zinc was not affected on drug administration. This steroidal contraceptive caused elevation in sodium-dependent glucose uptake, while the sodium-independent uptake remained unaltered. The kinetic parameters of glucose and leucine uptake indicate that MPA might be inducing the transport carrier protein of these nutrients as elevation in Vmax of these nutrients transport system was observed following its administration.

Alterations and reversibility of digestive and absorptive functions of rat intestine following medroxyprogesterone acetate administration

The long term (90 days) effects of medroxyprogesterone acetate (MPA) administration on the digestive and absorptive functions of the small gut have been investigated in female albino rats. The uptake of glucose and amino acids was found to be significantly increased while Ca++ uptake decreased following MPA treatment (35 mg/kg body weight). The observed increase in glucose uptake might be due to carrier mediated transport in enterocytes and not to a change in cell number. The Michaelis constant for glucose uptake was not altered by MPA. Activities of brush border membrane disaccharidases, leucine aminopeptidase and basolateral membrane enzyme Na+, K+-ATPase were significantly increased in response to MPA treatment. It was observed that these biochemical alterations caused by MPA in intestinal digestive and absorptive functions were reversible by 5 weeks after termination of the drug treatment. The action of the drug appears to closely resemble that of known effects of glucocorticoids on intestinal mucosa.

Degenerative and regenerative changes in central projections of glossopharyngeal and vagal sensory neurons after peripheral axotomy in cats: a structural basis for central reorganization of arterial chemoreflex pathways

Hypoxic hyperventilation in cats is a reflex normally initiated by afferent impulses originating in the carotid body and conducted to the brain stem by the carotid sinus nerves. The reflex response is abolished acutely after section of carotid sinus nerves and excision of the carotid bodies; but, chronically, there is a chemoreflex restoration which is mediated by the aortic body via the aortic depressor nerves. The restoration is associated temporally with changes in efficacy of ventilatory reflexes elicited by electrically stimulating carotid sinus and aortic depressor nerves, and these changes are postulated to reflect a central reorganization of the reflex pathways. In the present study, histological and ultrastructural techniques were used to investigate the neuroanatomical basis of the reorganization. The brain stem of the cat was examined using the Fink-Heimer silver stain to determine if degenerating axons were present following section of the carotid sinus nerve peripheral to its sensory ganglion. Degeneration was found 4-15 days postoperatively and the distribution of the axons corresponded with that reported for central projections of carotid sinus nerves labeled by transganglionic transport of horseradish peroxidase. The fine structure of nerve terminals in nucleus tractus solitarius was then examined with electron microscopy after cutting the vagus and glossopharyngeal nerves unilaterally peripheral to the sensory ganglia. Structural changes consistent with nerve terminal degeneration were observed 4-91 days postoperatively, and presumptive axonal sprouts were seen at 56-91 days.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of medroxyprogesterone acetate on hepatic lipid profile of female rats under various states of nutrition

The effect of medroxyprogesterone acetate (MPA) treatment on hepatic lipid profile was studied in female rats kept on protein-deficient diet, on normal restricted diet and on normal, ad libitum diet. A significant decline in total and free cholesterol levels was observed in rats kept on protein-deficient diet and on normal, restricted diet. However, protein-deficient animals exhibited a significant rise in the liver triglyceride level. In rats on normal, ad libitum diet only, MPA treatment resulted in elevated levels of triglycerides and increased esterification of cholesterol. This was mostly due to increased incorporation of acetate into esterified cholesterol and triglyceride as evident from studies using the labelled precursor. Total phospholipid content was found to be unaffected by MPA in all the groups suggesting that the drug and dietary protein level have no effect on hepatic phospholipid content.

Effect of medroxyprogesterone acetate on the digestive and absorptive functions of rat intestine

The effects of medroxyprogesterone acetate (MPA) on the digestive and absorptive functions of the small intestinal epithelium have been investigated in female albino rats. The transport of sodium-dependent glucose was significantly enhanced while sodium-independent transport remained unaltered in drug-treated animals. The uptake of amino-acids was also considerably increased, while Ca++ uptake decreased significantly on administration of the drug at a dose of 35 mg/kg body weight once a week for 1 month. Kinetic studies of glucose transport in the presence of sodium ions revealed that MPA treatment affected the rate of uptake of glucose by elevating Vmax, but the Km value remained the same in treated and untreated animals. The administration of the drug also led to significant augmentation in the activities of the brush border enzymes, disaccharidases, and to an insignificant decrease in alkaline phosphatase. The activities of leucine aminopeptidase did not show any change. The enhancement in sucrase activity might be due to induction of the enzyme because only Vmax was elevated in treated animals. As concerns cellular enzymes, lactate dehydrogenase activity was significantly depressed. This study suggests that MPA also exerts glucocorticoid-like effects on the intestinal tissue.