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Biomedical subjects

M Hamosh

Publications and source records attributed to M Hamosh.

At least 109 records · Page 6Linked to original sources
PubMed1982

Congenital esophageal atresia: lipase activity is present in the esophageal pouch and stomach.

Lipolytic activity was studied in aspirates from the esophageal pouch and from the stomach of eight infants with congenital esophageal atresia. Lipolytic activity, tested with doubly labeled ([3H]glyceryl, [14C]fatty acid) long-chain triglyceride was present in esophageal and gastric aspirates. The activity in esophageal aspirates was in the range of 2.7-130 nmol/min/ml aspirate and that in gastric aspirates was in the range of 2.9-40.4 nmol/min/ml aspirate. The reaction products of lipolytic activity in esophageal and gastric aspirates were a mixture of mono- and diglycerides, glycerol, and free fatty acids. The lipolytic activity at the two sites--esophagus and stomach--varied with respect to pH optimum (5.0-7.6 and 6.0-6.5, respectively) and reaction products (glycerol 41.6 +/- 20% and 7.3 +/- 4.6%, respectively). These findings confirm the earlier observations that digestion of dietary fat is initiated in the stomach and suggest that the lipolytic activity present in gastric contents originates concomitantly from the oral-esophageal area as well as from the stomach. These studies do not exclude the possibility that the lipolytic activity in the stomach of infants with esophageal atresia could originate in regurgitated intestinal contents.

Esophageal Atresia↗
PubMed1982

The lipolytic triad: human lingual, breast milk, and pancreatic lipases: physiological implications of their characteristics in digestion of dietary fats.

The characteristics of human lingual, breast milk, and pancreatic lipases as related to the digestion of dietary fats in infants are discussed. The activity and specificity of these enzymes and structure of the dietary fats largely determine the rates of lipolysis, the types of digestion products formed, and the rates of absorption. Also possibly influenced are micelle formation, intestinal health, breast milk jaundice, and the absorption of other nutrients. In premature infants, the action of lingual and breast milk lipase are particularly important in the absorption of dietary fatty acids.

Bile Acids and Salts↗
PubMed1981

Postheparin lipolytic activity and Intralipid clearance in very low-birth-weight infants.

The effect of heparin (10 U/kg) on serum lipolytic activity, triglyceride and FFA levels, during four hours infusion of 0.5 gm/kg Intralipid was measured in 18 AGA infants, 25 to 32 weeks' gestational age. PHLA, TG, and FFA were measured at 0, 10, 30, 120, and 240 minutes of infusion of Intralipid, before and following a bolus of 10 U/kg heparin iv. Lipolytic activity, measured by hydrolysis of activated tri-3H-oleate and expressed in mumol FFA released per milliliter serum per hour, was not detected in serum before heparin administration. Ten minutes after heparin administration peak PHLA was significantly higher in infants of 27 to 32 weeks' gestation than in infants of 25 to 26 weeks' gestation. There was no significant difference in peak PHLA between infants of 27 to 28 and 29 to 32 weeks' gestation. PHLA returned to baseline (zero) two hours after heparin administration in all infants. Infants of 25 to 26 weeks' gestational age had significantly higher concentrations of serum triglycerides before and during Intralipid infusion than in infants of 27 to 32 weeks' gestational age. Although there was a transient rise in FFA 10 and 30 minutes after heparin administration, the levels of FFA and triglycerides were not different at the end of infusion with or without heparin in either group, suggesting that a single bolus of heparin has only a transient effect on Intralipid clearance.

Fatty Acids, Nonesterified↗
PubMed1981

Effect of dexamethasone on lipoprotein lipase activity of fetal rat lung.

Dexamethasone was administered by continuous subcutaneous infusions (16 microgram/kg/h) to pregnant rats from day 16 of gestation. Administration of the hormone markedly affected maternal and fetal weight gain, fetal lung:body weight ratio and lipoprotein lipase activity of the lung. Cumulative maternal weight gain from days 15-21 of gestation was 80 +/- 4.0 g in control and 30 +/- 10 g in dexamethasone-treated rats. Fetal weight at 22 days of gestation and 1 day after birth was 5.5 +/- 0.39 and 8.6 +/- 0.30 in control and 4.65 +/- 0.26 and 5.9 +/- 0.34 in dexamethasone-treated rats. The ratio of lung weight to body weight was lower throughout the last 5 days of gestation in dexamethasone-treated than in control rats. Dexamethasone administration led to a 2- to 3-fold increase in lipoprotein lipase activity levels in fetal rat lung at 19 and 20 days' gestation and prevented the decline in enzyme activity shortly before birth. Stimulation of fetal lung lipoprotein lipase activity suggests that increased uptake of triglyceride-fatty acids by the lung could be a contributory factor to corticosteroid-enhanced surfactant synthesis.

Animal Nutritional Physiological Phenomena↗
PubMed1981

Fat digestion in the newborn. Characterization of lipase in gastric aspirates of premature and term infants.

We have measured lipolytic activity in gastric aspirates obtained at birth in a group of 142 infants. The infants ranged in gestational age from 26 to 41 wk. Lipolytic activity, measured by the hydrolysis of long chain triglyceride ([tri-(3)H]oleate), and expressed as nanomoles FFA per milliliter gastric aspirate per minute was 333+/-66 in 55 small premature infants (gestational age 26-34 wk and body wt 750-2,000 g) and 558+/-45 in a group of 87 larger infants (gestational age 35-41 wk and body wt 2,020-4,000 g). No activity was detected in seven infants with an unusually low pH in the gastric aspirate, 2.88+/-0.44 (compared with a mean pH level of 5.59+/-0.22 in the other 135 infants). Attempts to characterize this lipase showed that it has a molecular weight of 44-48,000, pH optimum of 3.0-5.0, that FFA acceptors (albumin) stimulate activity, whereas bile salts, taurocholate and glycocholate, cause marked inhibition at concentration >3 mM. Our survey shows that enzyme activity is present as early as 26 wk of gestation, increases with gestational age, and has the same characteristics throughout gestation. The data show that the lipase in gastric aspirates differs from pancreatic lipase, but closely resembles human and rat lingual lipase. Because the lipase has a low pH optimum and does not require bile salts, it can act in the stomach where it initiates the hydrolysis of dietary fat. We suggest that intragastric lipolysis is probably of major importance in the newborn and especially in the premature infant where it compensates not only for low pancreatic lipase, but in addition, helps to overcome the temporary bile salt deficiency through the formation of amphiphilic reaction products.

Dietary Fats↗
PubMed1981

Pathways of palmitate metabolism in the isolated rat lung.

Plasma fatty acids represent major precursors of lung lipids. In this study, the pathways of palmitate metabolism were measured in an isolated perfused rat lung. Lungs were ventilated with 5% CO2 in air and perfused with Krebs-Ringer bicarbonate containing 3% serum albumin and 0.25 mM [U-14C] and [9, 10(-3)H] palmitate. Fatty acid utilization was estimated by recovery of radiolabel in products of metabolism. Fourteen percent of a total 14C-fatty-acid utilization of 4.5 mumol fatty acid/100 min/g dry wt. was recovered as 14CO2. Degradation of fatty acid to acetyl CoA was indicated by a 3H2O production that was twice fatty acid oxidation to CO2. The majority of palmitate was recovered in lung phosphatidylcholines with a 14C to 3H ratio of 1.4 accounting for differences between 14C and 3H2O productions. Addition of glucose to the perfusate decreased fatty acid oxidation to CO2 by 32% but had no effect on 14C recovery in phospholipids. Perfusion with the uncoupler of oxidative phosphorylation 2,4-dinitrophenol stimulated fatty acid oxidation twofold but decreased 14C incorporation into lipids. These data together with estimates of fatty acid synthesis based on 3H2O incorporation into lipids, suggested that exogenous fatty acids and glucose both represent sources of carbon for de novo fatty acid synthesis and energy production.

Animals↗
PubMed1981

Fat digestion in very low-birth-weight infants: effect of addition of human milk to low-birth-weight formula.

The possible compensatory role of human milk lipase in the digestion of dietary fat was examined in a group of very low-birth-weight infants. Fat excretion was studied in 15 preterm infants of gestational age 26 to 33 weeks and birth weight 660 to 1,695 gm. The amount and composition of fecal fat were determined in stools collected for 72 hours. Eight infants were fed Similac 24 LBW exclusively and seven infants were fed a mixture of fresh human milk (40%) and formula (60%). Fat excretion was lower in infants fed a mixture of human milk and formula than in infants fed formula only (4.7% -+/- 0.50% vs 11.9% +/- 1.4% of intake, respectively). Excretion of calcium soaps, when expressed as percent of total fat, was higher in the group fed the human milk-containing diet (18.9% +/- 13.5%), than in the group fed formula only (6.8 +/- 2.5%); however, the absolute amounts excreted were similar in both groups (65 +/- 46 and 45 +/- 17 mg/kg/day, respectively). The lower fat excretion in infants fed a mixture of fresh human milk and formula could be related to the lipase present in human milk. These data suggest that human milk lipase probably contributes to the digestion and absorption of dietary fat in the "tiny premature" infant.

Dietary Fats↗
PubMed1980

Serum prolactin and respiratory distress syndrome in the newborn.

Prolactin levels were measured in cord blood by radioimmunoassay in 57 premature infants between 26 and 36 weeks of gestation. The level of prolactin was in the range of 20 to 600 ng/ml. Twenty-three of the infants subsequently developed respiratory distress syndrome (RDS). The mean cord prolactin in the infants with RDS was 140 +/- 30.7 ng/ml, whereas in the healthy infants it was 276.4 +/- 26.4 ng/ml. Cord prolactin levels less than 140 ng/ml were associated with a high incidence of RDS: of 25 infants with prolactin levels of less than 140 ng/ml, 19(76%) had RDS. Of the 34 healthy infants, 28(82%) had prolactin levels above 140 ng/ml. The highest levels (500 ng/ml) or prolactin in the group of infants with RDS were in two infants of diabetic mothers. The data suggest that prolactin might have a role in lung maturation in the human fetus.

Female↗
PubMed1979

Cachexia of malignancy: potential role of insulin in nutritional management.

Patients manifesting the syndrome of cachexia of malignancy exhibit an abnormal diabetic glucose tolerance. In our patients this has been correlated with a marked resistance to administered insulin, while insulin receptors on monocytes are normal. Lipolysis remains responsive to the effects of insulin. The oxidation of FFA, as a substrate for metabolism, has been reported to be increased, and the utilization of glucose as a metabolic fuel is reduced. Increased Cori cycle activity has been demonstrated, which produces an enhanced gluconeogenesis from lactate and amino acids; there is an expenditure of 6 ATP for the synthesis of each mole of glucose. An attempt to interrupt the Cori cycle in man, using hydrazine sulfate to inhibit the enzyme phosphoenolpyruvate carboxykinase, has not resulted in reproducible clinical benefit. However, successful treatment of the underlying tumor may produce a total reversal of the cachexia syndrome, suggesting that neoplasms have the potential to elaborate an, as yet, unidentified metabolic toxin. The use of insulin to counteract the reported abnormalities should be examined as a possible supportive measure in the total nutritional management of the cancer patient.

Amino Acids↗