MolCom: a method to compare protein molecules based on 3-D structural and chemical similarity.

This paper describes an improved method for conducting global feature comparisons of protein molecules in three dimensions and for producing a new form of multiple structure alignment. Our automated MolCom method incorporates an octtree strategy to partition and examine molecular properties in three-dimensional space at multiple levels of analysis. The MolCom method's multiple alignment is in the form of an octtree which locates regions in three-dimensional space where correspondence between molecules is identified based on a dynamic set of molecular features. MolCom offers a practical solution to the inherent compromise between computational complexity and analytical detail. MolCom is currently the only method that can analyze and compare a series of defined physicochemical properties using multiple, simultaneous levels of resolution. It is also the only method that provides a consensus structure outlining precisely where the similarity exists in three-dimensional space. Using a modest-sized collection of structural properties, separate experiments were conducted to calibrate MolCom and to verify that the spatial analyses and resulting structure alignments accurately identified both similar and dissimilar structures. The accuracy of MolCom was found to be over 99% and the similarity scores correlated strongly with the z-scores of the Alignment by Incremental Combinatorial Extension of the Optimal Path method.

Vanadate induces normolipidemia and a reduction in the levels of hepatic lipogenic enzymes in obese Zucker rat.

The effects of vanadate administration on the plasma lipids and hepatic lipogenic enzymes were investigated in Zucker (fa/fa) rat, a model for obesity and non insulin-dependent diabetes. These animals were administered sodium orthovanadate through drinking water for a period of four months. The plasma levels of insulin, triacylglycerols and total cholesterol were significantly (p < 0.001) elevated in untreated obese control rats as compared to the lean animals. In the livers of obese rats, the number of insulin receptors decreased by 60% and the activities of lipogenic enzymes acetyl-CoA carboxylase and ATP-citrate lyase increased by 4.7- and 5.6-folds, respectively. The messenger RNA for ATP-citrate lyase as measured by Northern blot analysis showed a parallel increase in obese control rats. Treatment of these rats with vanadate caused 56-77% decreases in the plasma levels of insulin, triacylglycerols and total cholesterol. The insulin receptor numbers in vanadate-treated obese rats increased (119%) compared to levels in untreated obese animals. The elevated activities of acetyl-CoA carboxylase and ATP-citrate lyase observed in livers of obese rats were significantly reduced by vanadate. The messenger RNA for ATP-citrate lyase also decreased in vanadate-treated obese rats back to the lean control levels. This study demonstrates that vanadate exerts potent actions on lipid metabolism in diabetic animals in addition to the recognized effects on glucose homeostasis.

Using pyridoxine to treat carpal tunnel syndrome. Randomized control trial.

In this study, we examined prospectively the effect of pyridoxine on idiopathic carpal tunnel syndrome. Thirty-two patients with the disease were randomized to receive treatment or placebo. No differences in outcome were found in electrophysiologic signs, clinical signs, or significant symptoms. Our findings do not support the use of pyridoxine for treating carpal tunnel syndrome.

Effects of vanadate administration on the high sucrose diet-induced aberrations in normal rats.

Effects of feeding sucrose rich diet supplemented with and without the insulinmimetic agent vanadate for a period of six weeks were studied in rats. Sucrose diet caused hypertriglyceridemia (140% increase), hyperinsulinemia (120% increase) and significant elevations in the levels of glucose (p < 0.001) and cholesterol (p < 0.05) in plasma as compared to control starch fed rats. Activities of hepatic lipogenic enzymes, ATP-citrate lyase, glucose 6-phosphate dehydrogenase and malic enzyme increased by 100-150% as a result of sucrose feeding. However, glycogen content and the activities of glycogen synthase and phosphorylase in liver remained unaltered in these animals. The plasma levels of triacylglycerols and insulin in the rats fed on vanadate supplemented sucrose diet were 65% and 85% less, respectively as compared to rats on sucrose diet without vanadate. The concentrations of glucose and cholesterol in plasma and the activities of lipogenic enzymes in liver did not show any elevation in sucrose fed rats when supplemented with vanadate. These data indicate that the sucrose diet-induced metabolic aberrations can be prevented by the insulin-mimetic agent, vanadate.

Effects of high sucrose diet on insulin-like effects of vanadate in diabetic rats.

The insulin-like effects of vanadate were compared in streptozotocin-induced diabetic rats fed on high starch control and high sucrose diets for a period of six weeks. Diabetic rats in both diet groups were characterized by hypoinsulinemia, hyperglycemia (6.8-7.0 fold increase) and significant decreases (p < 0.001) in the activities of glycogen synthase, phosphorylase and lipogenic enzymes, ATP-citrate lyase, glucose 6-phosphate dehydrogenase and malic enzyme in liver. There were no diet-dependent differences in these abnormalities. However, the insulin-mimetic agent vanadate was more effective in diabetic rats fed sucrose diet as compared to animals fed control starch diet. Vanadate administration resulted in 30% and 64% decreases in plasma glucose levels in diabetic rats fed control and sucrose diets, respectively. The activities of glycogen synthase (active) and phosphorylase (active and total) were restored significantly by vanadate in control (p < 0.05-0.01) and sucrose (p < 0.001) diets fed diabetic rats. This insulin-mimetic agent increased the activities of hepatic lipogenic enzymes in control diet fed rats to 38-47% of normal levels whereas in sucrose fed group it completely restored the activities. Sucrose diet caused a distinct effect on the plasma levels of triacylglycerol (4-fold increase) and apolipoprotein B (2.8-fold increase) in diabetic rats and vanadate supplementation decreased their levels by 65-75%. These data indicate that vanadate exerts insulin-like effects in diabetic rats more effectively in sucrose fed group than the animals fed control diet. In addition, vanadate also prevents sucrose-induced hypertriglyceridemia.

Long-term effects of vanadate treatment on glycogen metabolizing and lipogenic enzymes of liver in genetically diabetic (db/db) mice.

The effect of long-term (12 weeks) oral treatment with sodium orthovanadate on hepatic glycogen metabolizing and lipogenic enzymes was studied in genetically diabetic db/db mice. These mice were characterized by significant (P less than .001) obesity, hyperglycemia, and hyperinsulinemia. Vanadate administration led to significant decreases in body weight (P less than .001) and plasma insulin levels (P less than .01) and the mice became normoglycemic. The total glycogen synthase (EC 2.4.1.11) activity in the livers of diabetic mice showed a 47% increase, which did not undergo any significant change after treatment with vanadate. Hepatic phosphorylase (EC 2.4.1.1) activities (a and total) showed twofold increases in db/db mice when compared with the nondiabetic ones. Vanadate caused significant decreases in phosphorylase a (P less than .02) and total phosphorylase (P less than .001) activities. Glucose-6-phosphate dehydrogenase (EC 1.1.1.49) and malic enzyme (EC 1.1.1.40) in diabetic liver had differential alterations, as indicated by a 50% decrease in glucose-6-phosphate dehydrogenase and 160% increase in malic enzyme activities. Vanadate administration led to normalization of both enzyme activities. In nondiabetic mice, vanadate treatment did not cause changes in any parameter, except for a 46% decrease in plasma insulin levels. This investigation indicates that vanadate can normalize many of the metabolic abnormalities seen in the liver of genetically diabetic db/db mice, a model for non-insulin-dependent diabetes mellitus (NIDDM). Vanadate also causes a decrease in plasma insulin level, along with normalization of plasma glucose, which suggests a partial reversal of insulin resistance.

Insulin-like effect of vanadate on malic enzyme and glucose-6-phosphate dehydrogenase activities in streptozotocin-induced diabetic rat liver.

The effect of oral administration of sodium orthovanadate on hepatic malic enzyme (EC 1.1.1.40) and glucose-6-phosphate dehydrogenase (EC 1.1.1.49) activities was investigated in nondiabetic and diabetic rats. Streptozotocin-induced diabetic rats were characterized by 4.7-fold increase in plasma glucose and 82% decrease in plasma insulin levels. The activities of hepatic malic enzyme and glucose-6-phosphate dehydrogenase were also diminished (P less than 0.001). Vanadate treatment in diabetic rats led to a significant decrease (P less than 0.001) in plasma glucose levels and to the normalization of enzyme activities, but it did not alter plasma insulin levels. In nondiabetic rats vanadate decreased the plasma insulin level by 64% without altering the enzyme activities. Significant correlation was observed between plasma insulin and hepatic lipogenic enzyme activities in untreated and vanadate-treated rats. Vanadate administration caused a shift to left in this correlation suggesting improvement in insulin sensitivity.

Effects of litter size and diet composition on the development of some lipogenic enzymes in the liver and brown adipose tissue of the rat.

Male Sprague-Dawley rats were reared in litters of nine (normal litters) or 18 pups, and the dams were fed either a low fat (control) or a high fat diet. Offspring from each litter size and diet group were separated from the mothers on postnatal d 30, subdivided into two groups each, and fed either the control or the high fat diet until postnatal d 77. Hepatic glucose-6-phosphate dehydrogenase, malic enzyme and ATP-citrate lyase activities in the offspring from large litters were elevated during the early stages of weaning but later lagged behind enzyme activity of the normal litters. Brown adipose tissue enzymes also surged earlier in rats from large litters but did not fall below the values attained by the normal litters until postnatal d 32. Enzyme activities on postnatal d 77 revealed that large litter size and high fat feeding during or after weaning were associated with diminished hepatic enzyme activities. Hepatic glucose-6-phosphate dehydrogenase and ATP-citrate lyase activities also showed significant positive interaction between litter size and diet composition after weaning. Large litter size was also associated with diminished brown adipose tissue enzymes in the mature rats, but the composition of the weaning diet did not independently exert long-lasting changes in this tissue. Nevertheless, there was a positive interaction between litter size and diet composition during and after weaning. The data suggest that neonatal undernourishment can exert a long-term influence on the metabolic profiles of the animal, and that diet plays a role in modulating this influence.

Effects of diet and selected hormones on the activities of hepatic malic enzyme and glucose-6-phosphate dehydrogenase in infant, prematurely weaned rats.

Male Sprague-Dawley rats were weaned on postnatal d 17 to isocaloric diets in which fat supplied either 10% (PWC group) or 65% (PWF group) of the available energy. Compared with animals left with the dams to be weaned spontaneously to the maternal low fat diet (SWC group), the PWC rats showed early increases in the activities of liver glucose-6-phosphate dehydrogenase (G-6-PD) and malic enzyme (ME). The activity of G-6-PD was diminished in the PWF group, but the early rise in liver ME activity attendant on premature weaning was not prevented. Premature weaning, regardless of diet, decreased plasma glucagon levels within 1 d. Hydrocortisone failed to evoke hepatic ME activity in SWC rats; similarly, corticosterone and insulin, separately or together, did not affect ME activity in SWC rats. However, triiodothyronine evoked hepatic ME appearance within 1 d. Glucagon suppressed the expected rise in hepatic ME activity in PWC rats; in contrast, injection of glucagon antiserum into SWC rats led to the appearance of liver ME within 2 d. The data indicated that interaction among diet, glucagon and thyroid hormones may be part of the mechanism regulating the first appearance of ME in rat liver.

Weaning and metabolic regulation in the rat.

Premature weaning of rats to high carbohydrate diets causes a variety of short- and long-term changes in lipid metabolism, but the mechanisms involved are unclear. It is likely that interaction of diet with certain emerging hormonal control patterns during weaning might condition metabolic control and (or) subsequent adaptations in the adult organism. This implies that the adaptive responses of infant animals to diet may differ from those of the mature organism. For example, premature weaning leads to early appearance of rat liver malic enzyme (ME), even when fat supplies as much as 65% of the dietary energy; the same diet suppresses ME activity in 45-day-old rats. The levels of plasma glucagon and thyroid hormones are elevated during the weaning period. Several studies have shown that triiodothyronine evokes hepatic ME in suckling rats. Conversely, glucagon infusion into prematurely weaned rats suppresses the early appearance of the enzyme. Premature weaning, regardless of fat intake, leads to a rapid decline in plasma glucagon levels. Since glucagon is known to antagonize the actions of triiodothyronine on liver ME, the interaction of diet with glucagon and thyroid hormones is conceivably part of the mechanism responsible for the early appearance of hepatic malic enzyme, whereby the decline of plasma glucagon permits triiodothyronine to act on liver ME. Insulin probably exerts a permissive action subsequently. The manner in which these events relate to the long-term consequences of premature weaning is unknown.

Effect of weaning on the activities of glycogen synthase and phosphorylase in rat liver.

The effects of weaning on the level of glycogen and the activities of glycogen synthase and phosphorylase were determined in rat liver. Glycogen levels in rat liver increased at the start of the weaning period and reached a plateau on postnatal day 20. The active form of glycogen synthase increased until postnatal day 19 and then declined. Total glycogen synthase (active + inactive) remained high during the suckling period and declined to a new low level during the weaning period. The activity ratio (active/total) increased from day 16 to days 18-22 and then decreased to the same level as found during the suckling period. At the onset of weaning the active form of phosphorylase decreased, whereas total phosphorylase initially increased and then decreased after postnatal day 20. Both forms of phosphorylase increased again at the end of the weaning period. The activity ratio decreased at the start of weaning and remained low throughout the rest of the weaning period. The effects of premature weaning were similar to those observed in normally weaned animals, but the changes occurred sooner and were more pronounced.

Immunoquantitation of liver glucose-6-phosphate dehydrogenase and malic enzyme in normally and prematurely weaned rats.

Rat liver glucose-6-phosphate dehydrogenase and malic enzyme were purified and rabbit serum antibodies were prepared against each enzyme. The activities and quantities of both enzymes in the livers of infant rats were subsequently determined during the weaning period. Glucose-6-phosphate dehydrogenase was present and active in the liver of spontaneously weaned rats on postnatal day 17 and increased from postnatal day 21 onwards. Malic enzyme and its activity were undetectable on postnatal day 17. The latter enzyme was detected on postnatal day 21 and increased rapidly afterwards. These changes occurred sooner and were more pronounced when the rats were weaned prematurely on postnatal day 17, especially when the diet contained sucrose. The activities of both enzymes were highly correlated with the amounts of enzyme protein present throughout the experiment. It appeared that the activities of both enzymes in infant rats were likely to be regulated by altering their synthesis and (or) degradation, rather than by activation of existing proteins, assuming that the latter can be detected by the antibodies employed.

Effects of premature weaning on the metabolic response to dietary sucrose in adult rats.

Male, Sprague-Dawley rats were weaned prematurely (postnatal day 17) to a starch-based diet. At the age of 182 days, half of the rats were fed for 14 days a diet in which sucrose supplied 40% of the energy. Early weaning led to increases in the activities of hepatic glucose-6-phosphate dehydrogenase (G6PD) and malic enzyme (ME). Compared with spontaneously weaned rats, prematurely weaned animals also showed increases in hepatic lipogenesis in vivo and in liver cholesterol levels. However, early weaning did not influence intraperitoneal glucose tolerance, plasma cholesterol concentrations or the activities of hepatic ketohexokinase (KHK), fructose-1-phosphate aldolase (FIPA) and triokinase (TK). Sucrose feeding led to deterioration of glucose tolerance and to enhanced hepatic lipogenesis in vivo. Sucrose-fed rats also showed increases in the total activities of hepatic G6PD, ME, KHK, FIPA and TK. There was a positive interaction in effects on liver size between early weaning and dietary sucrose. In general, however, there were no differences between prematurely and normally weaned rats in their responses to sucrose. The results did not support the idea that dietary adaptations in early life alter the manner in which adult rats respond to dietary stimuli.

Immediate and late effects of premature weaning of rats to diets containing starch or low levels of sucrose.

Male, Sprague-Dawley rats were weaned prematurely (post-natal day 17) to a starch-based diet. Compared with normally-weaned rats, prematurely-weaned animals showed increases in the activities of hepatic glucose-6-phosphate dehydrogenase (G6PD) and malic enzyme (ME), and a fall in serum cholesterol level within 1 day. These enzymatic changes occurred sooner and were more pronounced when the diet of prematurely-weaned rats supplied 20% of the energy from sucrose, but the initial fall in serum cholesterol levels was smaller than in animals weaned prematurely to the control diet. Sucrose also led to an early rise in the activity of hepatic triokinase, but did not influence ketohexokinase or fructose-1-phosphate aldolase. Sucrose consumption resulted in an increase in lipogenesis in vivo in the liver and carcass and in serum cholesterol concentration on postnatal day 30, but animals weaned to the control diet were comparable with normally-weaned rats at the time. Early weaning led to elevation in the activities of hepatic G6PD and ME in 122-day-old rats, even though the control diet was fed from the age of 30 days. This response was not altered by the type of carbohydrate fed during the initial weaning period. Sucrose consumption during the weaning period did not exert long-term effects on the activities of hepatic fructolytic enzymes or in serum cholesterol levels.

Gluconeogenesis in meal-fed, vitamin B-6-deficient rats.

Male weanling rats were meal-fed (2 hours daily) on a vitamin B-6-deficient diet for 8 weeks; the controls were pair-fed. Vitamin B-6 deficiency led to the expected decreases in the activities of hepatic alanine and aspartate aminotransferases but did not influence those of glutamate dehydrogenase (EC 1.4.1.2), pyruvate carboxylase (EC 6.6.1.1), phosphoenolpyruvate carboxykinase (EC 4.1.1.32) and pyruvate kinase (EC 2.7.1.40). The ability of the deficient rats to incorporate 14C from labeled alanine into blood glucose and expired CO2 was diminished, but pyruvate-U-14C was utilized normally. The deficiency did not influence gluconeogenesis from glutamate or 2-oxoglutarate. Furthermore, the gluconeogenic potential of renal cortex slices incubated with pyruvate or 2-oxoglutarate was unaltered by the deficiency. These data suggest that the impairment of gluconeogenesis from amino acids in vitamin B-6 deficiency may be the consequence of diminished transamination prior to oxidative deamination.

Nutritional status of a select group of free-living elderly people in Vancouver.

A study was conducted to determine the nutritional status of the free-living elderly population in Vancouver. The response rate of the sample was low. Dietary information from 104 single men and women and 23 couples was collected by the 24-hour recall method. Biochemical tests in 56 single individuals and 13 couples included measurement of hemoglobin concentration and hematocrit, plasma analysis for concentrations of total protein, iron, carotene, vitamin A, ascorbic acid, vitamin E and cholesterol and for transferrin saturation, and urine analysis for concentrations of creatinine, thiamin, riboflavin and N(1)-methylnicotinamide.Mean energy intakes were considerably below the Dietary Standard for Canada. However, mean intakes of individual nutrients were similar to or in excess of the Dietary Standard for Canada for single men and women and for married men. Married women had low average intakes of calcium, iron, thiamin and riboflavin but adequate intakes of other nutrients. Mean values for biochemical variables were within the accepted range as defined by the Interdepartmental Committee of Nutrition for National Defense in the United States. According to the Nutrition Canada definitions of "high risk" there were no individuals in high-risk categories for any biochemical variable except plasma cholesterol concentration and transferrin saturation. The dietary and biochemical data indicated that the nutritional status in this select group of elderly persons was good except for intake of total energy and, in married women, of calcium, iron, thiamin and riboflavin.