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N Kretchmer

Publications and source records attributed to N Kretchmer.

At least 19 recordsLinked to original sources
PubMed1991

Intestinal absorption of fructose in the rat.

The objective of this study was to investigate the mechanisms involved in intestinal absorption of fructose. The results indicate that adult rats readily absorbed 0.4 g of fructose, an amount equivalent to 1.4-1.6 g fructose/kg body wt. Acute malabsorption of fructose occurred with doses greater than 0.6 g (2.1-2.4 g/kg body wt). Continued exposure to dietary fructose resulted in a decrease in the evidence of colonic fermentation. Glucose or galactose administered with fructose enhanced the absorption of fructose. The greatest absorption was observed when equal amounts of fructose and glucose were given simultaneously. If glucose was ingested as a polymer (starch or dextrin), the stimulatory effect was dependent on the digestibility of the polymer. Sucrose given with the fructose and glucose diminished the absorption of fructose. Acarbazone, a specific inhibitor of alpha-glucosidases, including sucrase, also inhibited the facilitating effect of glucose and galactose in absorption of fructose. These results give evidence for joint absorption of the two monosaccharides, fructose and glucose.

Acarbose↗
PubMed1991

Influence of maternal body habitus and glucose tolerance on birth weight.

Many physicians believe that macrosomia is a hallmark of a pregnancy complicated by glucose intolerance. Because the prevalence of obesity is increased among women with gestational diabetes, fetal overgrowth may be attributable at least in part to maternal obesity. We studied 2069 black, Latina, Chinese, and white mother-infant pairs to determine the interaction between maternal body habitus, maternal glucose homeostasis, and certain indices of fetal growth. Chinese women had a significantly higher serum glucose 1 hour after administration of 50 g glucose (136.6 +/- 32.7 mg/dL) than any of the other three ethnic groups. Black women had a significantly lower value for glucose (114.8 +/- 28.2 mg/dL) than either Chinese or Latina women (124.9 +/- 31.4 mg/dL). Results for Latina and white women (121.5 +/- 26.2 mg/dL) were not significantly different. Body mass index (BMI) was used to classify the subjects. The regression coefficient for the entire sample indicated a modest association of glucose with increased birth weight when maternal BMI was controlled. The BMI of the Chinese infants had a significant association with higher concentrations of glucose after administration of 50 g glucose. Maternal body habitus should be considered a major confounder in studies of the relationship of maternal glucose tolerance and infant birth weight.

Birth Weight↗
PubMed1990

Renal trehalase: function and development.

1. Following injection of trehalose into the bloodstream, no trehalose was found in urine of rabbits until the concentration of trehalose in blood exceeded 0.6 mg/ml. 2. Absence of trehalose in urine of the rabbit when the concentration of the sugar in blood is elevated supports the hypothesis that renal trehalase functions as a digestive enzyme in kidney. 3. The rat does not possess renal trehalase, and excretion of trehalose was in direct relation to the concentration of trehalose in blood. 4. There are differences in expression of the disaccharidases in kidney and intestine although they share many structural and enzymatic characteristics.

Animals↗
PubMed1990

Glucose tolerance in pregnancy: ethnic variation and influence of body habitus.

Little is known about ethnic differences in glucose tolerance during pregnancy. In this study we examined 3366 Hispanic, Chinese, black, and non-Hispanic white women in a universal screening program for gestational diabetes mellitus. After maternal age and body mass index were controlled, Chinese women had a significantly higher serum glucose level 1 hour after 50 gm of oral glucose (134.8 +/- 1.2, mean +/- SE) than any of the remaining three groups. Black women had a significantly lower value (113.3 +/- 1.3, mean +/- SE) than either Chinese or Hispanic women (124.4 +/- 0.9, mean +/- SE). Results for Hispanic women and non-Hispanic white women (121.4 +/- 1.6, mean +/- SE) were not different. The screening glucose levels of Chinese women were substantially higher than other ethnic groups even when women with gestational diabetes were removed from the analysis, indicating that the observed differences were not solely due to a higher frequency of gestational diabetes among the Chinese. The incidence of gestational diabetes was significantly greater for Chinese (7.3%) and Hispanic (4.2%) women than for black (1.7%) and non-Hispanic white (1.6%) women. Among women who had a 3-hour glucose tolerance test, the area under the glucose curve was significantly associated with maternal age and body mass index. The demonstrated heterogeneity of glucose tolerance between ethnic groups may be of importance in determining the threshold for diabetic fetopathy, and it is possible that ethnicity-specific standards will need to be developed.

Asian People↗
PubMed1990

Development of ornithine metabolism in the mouse intestine.

Circulating arginine available for synthesis of protein is produced in the kidney of the adult mammal by the action of the last two enzymes of the urea cycle, argininosuccinate synthase and argininosuccinate lyase. In a previous publication, we reported the presence of a complete biosynthetic pathway for arginine in the intestine of the neonatal mouse at a time when no other endogenous sources of arginine were available. Our present study was aimed at the determination of the source of ornithine used by the intestine of the neonatal mouse for the synthesis of arginine. We established the developmental profile of the two intestinal mitochondrial enzymes, pyrroline 5-carboxylate synthase and ornithine aminotransferase, responsible for the conversion of glutamate to ornithine. Both enzymatic activities were found to be significantly elevated throughout the suckling period with a peak of activity during the 2nd wk of life. Glutamate dehydrogenase activity in the intestine did not appear to be developmentally regulated during the suckling and weaning periods; therefore, this enzyme was used as a convenient marker to quantify mitochondrial preparations. Ornithine decarboxylase activity was undetectable in the intestine of the mouse during the suckling period and was detected briefly at weaning, indicating that ornithine synthesized in the intestinal mitochondria is probably not diverted actively into the polyamine pathway and is available for synthesis of arginine by the enzymes of the urea cycle.

Animals↗
PubMed1988

Synthesis of hepatic protein during pregnancy in the rat.

The accumulation of hepatic protein during pregnancy in the rat could be the result of a decrease in rate of degradation, an increase in rate of synthesis or both. The purpose of the study was to determine relative rates of synthesis of hepatic protein for pregnant and nonpregnant rats. Pregnant and nonpregnant Sprague-Dawley rats were fed a 20% casein, purified diet from the first day of gestation. On d 19 of gestation the rats were killed. Livers were weighed and assayed for RNA. Relative synthesis rates of hepatic protein were assessed by homologous in vitro cell-free translation. RNA per liver and per g liver and incorporation of labeled leucine into protein per liver and per unit of RNA were greater for the pregnant rats than the nonpregnant rats. In conclusion, accumulation of hepatic protein during pregnancy is at least partially the result of an increase in rate of synthesis.

Animals↗
PubMed1988

Utilization of glutamine in the developing rat jejunum.

The activity of glutaminase was measured in the jejunum of rats during the suckling period. Activity increased significantly (P less than 0.05) from 2.37 +/- 0.31 mol glutamate/(mg jejunal protein.h) (X +/- SD) in the first week to 3.50 +/- 0.99 in the second week and 4.75 +/- 0.96 during the third week. The quantity of the glutaminase protein, measured with a dot immunobinding assay, remained constant during the first (592 +/- 174 cpm bound/g protein) and second (599 +/- 125) weeks and then increased significantly by the third week (784 +/- 270) after birth. These results indicate that the activity of glutaminase is regulated by alterations in both the quantity and activity of glutaminase protein. The oxidation of [U-14C]glutamine to 14CO2 in vitro also increased during the suckling period, with significantly (P less than 0.05) higher rates of oxidation observed by the third week after birth. The capacity of the developing rat jejunum to utilize both glutamine and -hydroxybutyrate (BHB) as fuel sources to support [methyl-3H]thymidine (3HTdR) incorporation was also determined. Addition of glutamine to jejunal homogenates in vitro resulted in a significantly (P greater than 0.05) higher rate of 3HTdR incorporation than was observed with either glucose or BHB as a fuel source during the early suckling period. In the late suckling period, the addition of BHB and glutamine together resulted in significantly (P greater than 0.05) higher rates of 3HTdR incorporation than that found with glucose as a fuel source. These data suggest that both glutamine and BHB are important fuel sources in the jejunum during the suckling period.

Animals↗
PubMed1987

Growth of immigrant children in the newcomer schools of San Francisco.

A semilongitudinal study on growth and development was initiated on immigrant and refugee school-aged children in San Francisco. Anthropometric values (height, weight, arm circumference, and triceps and subscapular skinfolds) were collected soon after their arrival in the United States and repeated at 3-month intervals for 1 year. Data were analyzed by age-gender cohorts. z Score calculations for measures of height-for-age, weight-for-age, and weight-for-height demonstrated a significant overall deficiency in height-for-age and weight-for-age at the time of the first measurement. Comparisons with a US standard indicated that most of the children were between the fifth and 25th percentiles in these measures. There were fewer children who were significantly deficient in weight-for-height. Calculations for median growth rate indicated that most cohorts exhibited a median growth velocity that was close to or exceeded the median for US white children. There was also significant improvement in weight-for-age. The results indicated that these immigrant and refugee children accelerated their growth markedly in an optimum nutritional environment and were in a period of catch-up growth.

Body Height↗
PubMed1986

Effect of diabetic ketosis on jejunal glutaminase.

The intestine is capable of shifting its major fuel source from glutamine in the fed animal to ketone bodies in the fasted animal. Glutaminase (EC 3.5.1.2), the entry enzyme of glutamine oxidation, was examined for its function as a determinant in the utilization of jejunal fuel during diabetes and fasting. Male Sprague-Dawley rats were made ketotic to varied degrees by either fasting or the induction of diabetes with graded doses of streptozotocin (SZ). Specific activity of glutaminase was decreased in the diabetic animals to 64% (p less than 0.05) of controls in the group receiving 110 mg/kg SZ and 82% of controls in the group receiving 65 mg/kg SZ and to 78% (p less than 0.05) of controls in the fasted animals. The activity of glutaminase in the small intestine was negatively correlated to the concentration of beta-hydroxybutyrate in the plasma (r = -0.97, p less than 0.025) and jejunum (r = -0.92, p less than 0.05) for the four groups of animals. Specific activity of glutaminase was decreased in all cell types isolated along the villus-crypt axis of the small intestine from diabetic and fasted rats compared with control rats. The quantity of glutaminase-protein was determined by a dot immunobinding assay using an antibody to purified glutaminase. The activity of glutaminase relative to immunoreactive glutaminase-protein was significantly decreased (p less than 0.05) to 53% of control values in the 110 mg/kg SZ group, 77% in the 65 mg/kg SZ group, and 70% in the fasted group. These data indicate that an inactivation of glutaminase-protein may play a role in the ability of the intestine to shift its fuel source from glutamine to ketone bodies during diabetes and fasting.

3-Hydroxybutyric Acid↗
PubMed1986

Development of arginine-synthesizing enzymes in mouse intestine.

The urea biosynthetic pathway functions in mammalian liver to convert excess ammonia to urea and to maintain the concentration of ammonia in blood at nontoxic levels. This action is accomplished by enzymatic adaptation to quantitative changes in dietary protein. The first two enzymes of the pathway are found in the intestine of the adult mouse, but they do not adapt to dietary change. The enzymes in the intestine produce citrulline, which is carried by the bloodstream to the kidney, where it is converted by the next two enzymes of the pathway to arginine. This mechanism serves as the major source of circulating arginine. We have demonstrated that, at birth, the arginine-synthesizing enzymes in the kidney of the C57Bl/6 mouse are minimally developed, whereas in the intestine activity of carbamoyl-phosphate synthase is elevated and argininosuccinate synthase and lyase, usually present only in trace quantities in the adult intestine, are markedly increased in the newborn. The arginine formed cannot be converted to urea, since arginase does not appear in intestinal cells of the mouse until the age of 15 days. Except for liver, intestine has the most rapid protein turnover of any normal tissue. Our study indicates that, at a time when no other endogenous source of arginine for protein synthesis is available, the intestine of the newborn C57Bl mouse is capable of synthesizing arginine from either citrulline or NH3 and CO2.

Animals↗
PubMed1985

Primary cultures of rat pancreatic acinar cells in serum-free medium.

Rat pancreatic acinar cells were isolated and cultured in Ham's F12 medium with 15% bovine calf serum. Caerulein, insulin, somatostatin, and dexamethasone (DEX) had no effect on intracellular or secreted amylase in these cultured cells. A serum-free medium, using Waymouth's MB 752/1 supplemented with albumin, epidermal growth factor (EGF), DEX, and HEPES, was then developed to avoid serum factors that might mask hormonal effects. In this SF medium, pancreatic acinar cells maintained the morphological and ultrastructural characteristics of freshly isolated cells and secreted amylase in response to the secretagogue, carbamyl choline. Insulin, at a concentration of 1 microgram/ml, significantly increased intracellular and secreted amylase activity after 3 d. This model cell system can be used to study the regulation of the synthesis of amylase and other pancreatic enzymes in vitro.

Amylases↗
PubMed1979

Nutrition program.

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Government Agencies↗
PubMed1978

Lactose malabsorption among adult Indians of the Great Basin and American Southwest.

The prevalence of primary adult lactose malabsorption and the pattern of milk use were studied among 109 Indians from various tribes of the American Great Basin and Southwest. Included were 100 persons who reported being full-blooded Indians as well as three with Mexican admixture and 6 with some European ancestry. Lactose malabsorption was found in 92% of the full-blooded Indians but in only 50% Indians who acknowledged European admixture. These results agree with those of studies of native Americans done elsewhere which show very high prevalences of such lactose malabsorption among adults reported as fullblooded and lower prevalences among individuals with admitted European ancestors. The suggestion made is that in pre-Colombian times, before interbreeding with Europeans began on any scale, such lactose malabsorption may have been nearly universal among native American adults. Most of the Indians studied consumed abundant milk since childhood but were nevertheless predominantly malabsorbers as adults. This argues against the induction hypothesis advanced by some to explain the striking ethnic differences that occur around the world in primary adult lactose malabsorption.

Adult↗