Differences in cholecystokinin release and gallbladder contraction between emulsified and nonemulsified long-chain triglycerides.

BACKGROUND: Fat is a potent stimulus of cholecystokinin (CCK) release. Apart from lipolysis, fatty acid chain length, and saturation, emulsification may also determine the magnitude of CCK release. METHODS: We have studied the effect of emulsification of soybean oil on CCK and pancreatic polypeptide (PP) release (radioimmunoassay [RIA]) and gallbladder motility (ultrasonography). Six healthy subjects were studied on three separate occasions in random order during (1) intraduodenal administration of emulsified long-chain triglycerides (LCT) (6 mmol/h for 120 minutes); (2) equimolar amounts of nonemulsified LCT with addition of emulsifier; and (3) saline with emulsifier (control). RESULTS: Intraduodenal administration of both nonemulsified LCT and emulsified LCT induced significant (p < .05) increases in plasma CCK and PP levels and reductions in gallbladder volume. However, compared with nonemulsified LCT, emulsified LCT resulted in a readier and significantly stronger CCK release (212+/-62 pmol/L per 120 minutes vs 36+/-7 pmol/L per 120 minutes; p < .05); PP release (2034+/-461 pmol/L per 120 minutes vs 671+/-106 pmol/L per 120 minutes; p < .05); and gallbladder contraction (77%+/-2% vs 41%+/-7%; p < .05). No significant alterations were observed in plasma CCK or PP levels and gallbladder volume during administration of saline with emulsifier. CONCLUSIONS: Intraduodenal administration of a low-dose emulsified LCT more potently stimulates CCK and PP release and gallbladder contraction in comparison to equimolar amounts of nonemulsified LCT. These findings point to an important role for solubilization of LCT in determining the magnitude of CCK release from the intestine.     

The effect of artificial feeding on cholestasis, gallbladder sludge and lithiasis in infants: correlation with plasma cholecystokinin levels

The occurrence of hepatic cholestatis (judged by fasting serum bile acid levels), gallbladder sludge formation and lithiasis (ultrasonography) and their correlation with plasma cholecystokinin (CCK) levels was studied in a group of children on continuous total parenteral nutrition (TPN) (n = 95), and later in 40 of these children on cyclic TPN (cTPN). After resumption of oral feeding, 75 were studied on partial oral feeding (2-4 meals) and 40 on constant rate enteral nutrition (CREN) then 45 on total oral feeding (4-6 meals). Gallbladder sludge occurred in 23% of the children on TPN for 1 month and 32% of those on cTPN for 3 months. On CREN, the sludge rate was unchanged, but dropped significantly (17%) on partial oral feeding, and disappeared in children on total oral feeding. Serum bile acids were abnormal in 80% of children on TPN or cTPN and diminished significantly on total oral feeding only. Plasma CCK levels on TPN, cTPN and CREN were identical to fasting levels of children on total oral feeding. Plasma CCK levels increased significantly 1 h post-prandially during both partial (p < 0.02) and total oral feeding (p < 0.001). There was a significant negative correlation between the gallbladder sludge rate and CCK levels for all methods of feeding. This study demonstrates the frequent occurrence of hepatic cholestasis in infants, and the much lower frequency of gallbladder sludge in children compared to adults on TPN. Plasma CCK levels obtained during the different methods of feeding could explain the reduction and eventual disappearance of sludge following stimulation of CCK secretion by discontinuous feeding.     

Gallbladder contraction after hormonal manipulations in normal subjects and patients under total parenteral nutrition.

Total parenteral nutrition (TPN) induces biliary dilatation, sludge and formation of gallstones. Cholecystokinin (CCK) induces gallbladder (GB) contraction. During thyrotropin-releasing hormone (TRH) testing for thyroid function, we observed that patients felt a strong micturition reflex attributable to smooth muscle contraction of the bladder. The possibility of GB contraction after TRH administration was studied compared to cholecystokinin-octapeptide (CCK-OP) and/or fatty meal administration. The effect of intravenous (IV) CCK-OP, TRH and a combination of the two on GB volume was studied in normal volunteers without GB or liver disease and in patients receiving TPN for greater than 2 weeks. Subjects included six normal volunteers who received an oral fatty meal only, 18 other normal volunteers (Group A) and 18 TPN patients (Group B). Gallbladder contraction was estimated by ultrasound prior to and after administration of the fatty meal; in the other 36 subjects, GB contraction was calculated prior to and after administration of CCK-OP, TRH, or both. Results are expressed as a percentage of the GB basal volume using each subject as his or her own control. Group A and Group B were each divided into three equal subgroups receiving IV CCK-OP (A1, B1), TRH (A2, B2), or both (A3, B3).(ABSTRACT TRUNCATED AT 250 WORDS)     

Intravenous fat emulsion (intralipid) delays gastric emptying, but does not cause gastroesophageal reflux in healthy volunteers

The impact of overnight intravenous lipid emulsion (ILE) infusion on upper gastrointestinal tract physiology was assessed in 10 healthy volunteers. No changes in lower esophageal sphincter pressure (before infusion: 28 +/- 4 mm Hg; after infusion 20.5 +/- 3; p:NS), plasma concentrations of gastrointestinal hormones (gastrin: preprandial before/after lipids: 14 +/- 2.1/13 +/- 1.4 pM; postprandial before/after lipids: 28 +/- 2.7/30 +/- 3.4 pM, CCK: preprandial before/after lipids: 69 +/- 10/64 +/- 10 pM; postprandial before/after lipids: 96 +/- 11/95 +/- 12 pM; neurotensin: levels less than 6 pM in all samples; somatostatin levels undetectable in all samples) nor on pathologic gastroesophageal reflux episodes (% of time of pH less than 4, before/after lipids: 0.6 +/- 0.4/0.15 +/- 0.09), were found (p = NS). In contrast, technetium gastric emptying studies showed a significant delay when comparing pre- and post-lipid infusion values (37 +/- 4/54 +/- 4%) (p greater than 0.005). The mechanism of this effect remains unexplained.     

Comparison of substrate utilization by indirect calorimetry during cyclic and continuous total parenteral nutrition

Five male adult home patients were studied in a randomized order under continuous (24 h/d) and nocturnal cyclic (15 h/d) isocaloric, isonitrogenous total parenteral nutrition (TPN). They received 2626 +/- 265 total kcal/d as 60% dextrose and 40% lipids; the 3-h lipid infusion was followed by the dextrose amino acid infusion on both regimens. Substrate oxidation was measured by indirect calorimetry during four periods on the fourth day of each regimen. During cyclic TPN net lipogenesis occurred with a nonproteic respiratory quotient (npRQ) greater than 1 during dextrose amino acid infusion followed by net lipolysis with an npRQ less than 1 during the nonnourishing phase. In contrast, during continuous TPN net lipogenesis persisted with an npRQ greater than 1 over the 21 h of dextrose amino acid infusion. During the 3-h lipid infusion, fat oxidation was observed during both regimens but was more pronounced during cyclic TPN (p less than 0.05). As a consequence, 24-h lipid oxidation was higher and 24-h dextrose utilization lower during cyclic vs continuous TPN (p less than 0.05). These results suggest that cyclic TPN when alternating between substrate storage and oxidation, mimics the physiological pattern of oral feeding.     

Relative importance of amino acid infusion as a means of sparing protein in surgical patients

We performed isotopic infusions in 51 surgical patients to investigate the effectiveness of different substrates to conserve protein. All patients were initially studied in the basal state and then the effects of glucose infusion (GL, N = 13), lipid infusion (LIP, N = 11), or amino acid infusion (AA, N = 17) were determined. Ten patients receiving total parenteral nutrition (TPN) were also studied. The basal value for net protein catabolism (NPC) in GL patients was 1.53 +/- 0.4 (SEM) g/kg/day decreasing to 1.39 +/- 0.4 g/kg/day during glucose infusion (p less than 0.01). The basal NPC in the LIP group was 2.04 +/- 0.4 g/kg/day decreasing to 1.72 +/- 0.3 g/kg/day during lipid infusion (p less than 0.01). In the TPN patients the NPC was 0.79 +/- 0.46 g/kg/day whereas in the AA patients the basal value for NPC was 1.37 +/- 0.14 g/kg/day decreasing to -0.77 +/- 0.11 g/kg/day during amino acid infusion (p less than 0.0005). From our study we conclude that: (1) All substrates commonly used in intravenous feeding have the capacity to spare protein. (2) Protein sparing was more pronounced when a balanced amino acid infusion was used than with either glucose or lipid infusion alone. (3) This effect is not solely due to insulin secretion as larger insulin responses were seen with both GL and TPN patients. (4) These results may have implications for peripheral vein feeding with amino acid solutions where there is a contraindication for full TPN or the lack of resources for administering it.     

Comparative studies on a new concentrated fat emulsion: Intralipid 30% vs. 20%

A concentrated fat emulsion (Intralipid 30%) was tested for clinical tolerance and metabolic effects in 2 studies comparing it with Intralipid 20%. 24 healthy subjects were given 100-g fat infusions of the two emulsions over a period of 6 h on two different days in random order. At 6 h of infusion, the mean increase in the plasma triglyceride (TG) concentration was similar for the two emulsions (3.3 +/- 0.5 (SD) and 3.9 +/- 2.9 mmol/l for the 30% and 20% emulsions, respectively; NS). A significantly lower increase in plasma phospholipid (PL) concentration was noted with Intralipid 30% (0.27 +/- 0.24 vs. 0.88 +/- 0.62 mmol/l; p < 0.05). The increases in cholesterol and free fatty acid (FFA) levels were similar for the two emulsions. In another study, 20 postoperative patients were randomized to receive 100 g fat per day during 5 days as either Intralipid 30% or Intralipid 20%. Modest increases (less than 1 mmol/l) in TG, PL, FFA and cholesterol levels were noted on day 3 and one day after the completion of TPN (day 6) and there were no significant differences between the 2 groups. It is concluded that, apart from a less pronounced increase in plasma PL levels after 6 h of infusion, the metabolic effects of Intralipid 30% were similar to those observed with the 20% emulsion. The new concentrated fat emulsion was found to be clinically safe and could be considered for use in patients requiring TPN.     

Thermogenesis from intravenous medium-chain triglycerides

Eighteen hospitalized patients dependent on total parenteral nutrition (TPN) were randomly enrolled into a prospective study comparing intravenous long-chain triglycerides (LCT) with a physical mixture of 75% medium-chain triglycerides (MCT) and 25% LCT. The TPN was given continuously as amino acids and glucose over 5 days with the respective lipid emulsion given intermittently during each day for 10 hr. Indirect calorimetry was measured on each patient before the lipid emulsion was administered in the morning and again 10 hr later near the end of the lipid infusion, on days 1, 3, and 5. Resting energy expenditure, VO2, VCO2, and calculated fat oxidation were shown to increase during MCT infusion but not during LCT administration, (resting energy expenditure 899 +/- 37 to 1085 +/- 40, compared with 978 +/- 23 to 976 +/- 39, kcal/m2 body surface area [BSA]/day, respectively, p less than 0.0002; VO2: 129.9 +/- 5.2 to 157.2 +/- 5.9, compared with 140.9 +/- 3.6 to 141.2 +/- 5.9 ml O2/min/m2 BSA, respectively, p less than 0.0005; and VCO2: 110.7 +/- 4.4 to 127.5 +/- 4.3, compared with 118.3 +/- 2.8 to 118.0 +/- 5.3, ml CO2/min/m2 BSA, respectively, p less than 0.0076; calculated fat oxidation 10.7 +/- 1.5 to 19.3 +/- 2.4, compared with 20.0 +/- 2.7 to 20.0 +/- 3.6, kcal/m2 BSA/hr, respectively, p less than 0.014). Respiratory quotient tended to fall with lipid infusion but did not change statistically. Body temperatures were unaltered by either fat infusion. It is concluded that TPN consisting of MCT causes an increased thermogenesis, most likely through increased fat oxidation, reflective of MCT's property as an obligate fuel. The increased thermogenesis occurs without an increase in body temperature.     

Metabolic and thermogenic response to continuous and cyclic total parenteral nutrition in traumatised and infected patients

16 traumatised or infected patients on mechanical ventilation were randomised to continuous TPN or to cyclic TPN after a 24-h period of glucose infusion (1.25 kJ x kg BW(-1) x h(-1)). Energy supply was equivalent to 1.3 x baseline energy expenditure. Glucose, fat and amino acids were administered at a constant rate over 24 h in the continuous TPN group and over 12 h, followed by glucose (1.25 kJ x kg BW(-1) x h(-1)), in the cyclic TPN group. Nutrient-induced thermogenesis was lower during continuous than during cyclic TPN (5 +/- 4 vs. 12 +/- 7%, mean +/- SD, p < 0.05), as was the increase in CO(2) elimination (13 +/- 11 vs. 30 +/- 7%, respectively, p < 0.01). Energy balance was more positive during continuous TPN. In both groups, energy expenditure reached a plateau during the first 12 h of TPN infusion. The lower nutrient-induced thermogenesis and more positive energy balance, indicates a more efficient utilisation of nutrients during continuous than during cyclic TPN. The lower CO(2) production during continuous TPN, may be advantageous when respiratory function is compromised. The plateau in energy expenditure in response to TPN infusion may be useful as a guideline for nutritional therapy.     

Motility of the gastrointestinal tract and gallbladder during long-term total parenteral nutrition in dogs

BACKGROUND: The motility of the gastrointestinal tract during total parenteral nutrition (TPN) remains poorly understood. The objective of this study was to determine the motility pattern not only in the gastrointestinal tract but also in the gallbladders of dogs maintained by TPN. METHODS: Central venous catheters were inserted through the external jugular vein of 5 dogs and 6 strain gauge force transducers were sewn to the stomach, small intestine, and gallbladder. Two weeks later, oral food was discontinued and motility was recorded for 24 hours after the first migrating motor complex (MMC) was confirmed in the stomach as pre-TPN. TPN was started and continued for 4 weeks, and patterns of motor activity during TPN were recorded for 24 hours at the end of each week. RESULTS: The durations of MMC in the stomach, duodenum, and gallbladder in pre-TPN were 118 +/- 3 minutes, 118 +/- 2 minutes, and 118 +/- 2 minutes, respectively, but in the first week of TPN they were 432 +/- 56 minutes, 431 +/- 56 minutes, and 386 +/- 29 minutes, respectively. TPN times were significantly longer than those of pre-TPN (corrected p < .005). The durations of MMC in jejunoileum did not alter between pre-TPN and TPN. The occurrences of phase III in the stomach, duodenum, and gallbladder in pre-TPN were 12/d, but during TPN they were reduced significantly (corrected p < .005). CONCLUSIONS: TPN did not affect the motility of the jejunoileum but did inhibit the motor activities of the stomach, duodenum, and gallbladder. The inhibition of gallbladder contraction observed during TPN may be one of the factors inducing gallbladder disease.     

Coffee stimulation of cholecystokinin release and gallbladder contraction in humans

We studied the effect of the ingestion of 400 mL regular coffee on plasma cholecystokinin (CCK) concentrations and of 165 mL regular and decaffeinated coffee on plasma CCK and gallbladder contraction in six healthy regular coffee drinkers. Plasma CCK concentrations rose 3.3 +/- 0.4 pmol/L after 400 mL and 2.8 +/- 0.9 pmol/L after 165 mL regular coffee compared with 1.8 +/- 0.6 pmol/L after 165 mL decaffeinated coffee. These plasma CCK increments were greater than those after 400 and 165 mL of an isosmotic and isothermic sodium chloride solution (0.6 +/- 0.2 and 0.4 +/- 0.1 pmol/L, respectively). An average gallbladder contraction of 33 +/- 7% was observed after 165 mL regular coffee and 29 +/- 10% after 165 mL decaffeinated coffee, whereas after 165 mL sodium chloride the contraction was only 10 +/- 12%. We conclude that both regular coffee and decaffeinated coffee give rise to increments in plasma CCK and contractions of the gallbladder.     

Long-term parenteral nutrition in unrestrained nonhuman primates: an experimental model

A freely mobile jacket and tether system was developed for the investigation of total parenteral nutrition (TPN)-induced metabolic bone disease and complications of prolonged TPN in 12 Macaca fascicularis nonhuman primates. The animals received TPN for 49 +/- 7 d (means +/- SEM), providing 82 +/- 2 kcal.kg-1.d-1. Serum glucose increased from 3.6 +/- 0.2 mmol/L at baseline to 8.3 +/- 1.9 mmol/L (p less than 0.01) during TPN, and serum albumin decreased from 38 +/- 1 g/L at baseline to 29 +/- 1 g/L (p less than 0.001) during 2.75% amino acid TPN and 30 +/- 2 g/L (p less than 0.01) during 5% amino acid TPN infusion. No significant changes were seen in serum prealbumin, total protein, bilirubin, alanine aminotransferase, and 5'-nucleotidase during TPN infusion. Major complications included catheter sepsis, hyperglycemia, diarrhea, and premature death in six animals. Thus, metabolic complications of prolonged TPN support may be investigated in a freely mobile nonhuman primate.     

Parenteral nutrition in patients with liver cirrhosis. Effects on circulating levels of glucose and hormones and on cerebral function

The effects of 2 and 5 days of total parenteral nutrition (TPN; 70 g amino-acids, 100 g fat, 150 g glucose) on carbohydrate, fat and amino-acid levels and on cerebral function were investigated in 10 patients with alcoholic cirrhosis and 7 age-matched healthy controls. The results were compared to those after a standardised oral diet. During TPN, glucose concentrations increased slightly in both groups. Insulin concentrations also rose in both groups, but the rise was more pronounced in the patients, resulting in a 10-fold difference between the two groups after 6.5 hours (patients: 281 +/- 81 U/l; controls: 28 +/- 5 U/l; p < 0.02). Glucagon increased significantly during TPN in the patients only (33%, p < 0.05). Similar but less pronounced patterns were observed after the oral diet. The basal concentrations of free fatty acids and 3-OH-butyrate were higher in the patients than in the controls. However, during both oral and parenteral nutrition, the concentrations fell in both groups. For 3-OH-butyrate the difference between the groups disappeared, while the free fatty acid levels remained higher in the patients throughout the TPN administration. Basal triglyceride levels were similar in patients and controls and rose to a similar extent in both groups during TPN. Plasma amino-acid concentrations were typical for cirrhotic patients in the basal state: low levels of the branched-chain amino-acids (BCAA) and high concentrations of the aromatic amino-acids (AAA). During TPN BCAA, as well as AAA, increased in both patients and controls, resulting in unaltered BCAA AAA ratio. All patients performed poorly on psychometric tests (Number Connection Tests A and B; Digit Symbol) before the study, indicating subclinical encephalopathy. However, no deterioration was observed in any of the tests during five days of TPN. Similarly, EEG and visual evoked potentials were unchanged during the study, demonstrating that patients with severe alcoholic liver disease tolerate a balanced intravenous nutrition without adverse effects on cerebral function.     

Gallbladder contraction after administration of intravenous amino acids and long-chain triacylglycerols in humans.

We examined the possible physiologic effects of intravenous (IV) amino acids (AAs) and long-chain triacylglycerols (LCTs) on gallbladder (GB) motility and release of cholecystokinin (CCK) on humans. GB contraction was studied in normal volunteers after administration of a fatty meal and IV infusion of AA and LCT. The GB contraction volume was calculated with ultrasound. Cholecystokinin-8 (CCK-8) and cholecystokinin-33/39 (CCK-33/39) were measured by radio-immunoassay. Administration of a fatty meal resulted in GB contraction by 60% of its basal volume and was accompanied by an increase in the serum levels of both CCK-8 and CCK-33/39. Administration of IV AA and LCT resulted in GB contraction by 17 and 37%, respectively, of its basal volume. The latter contractions were accompanied by increased levels of CCK-8 only. We conclude that IV administration of AA and LCT can result in human GB contraction and induce the release of only CCK-8. Continuous IV administration of AA and LCT for greater than 2h causes exhaustion of CCK-8 release, so that the GB returns to its initial volume.     

Clonidine reduces diarrhea and sodium loss in patients with proximal jejunostomy: a controlled study

BACKGROUND: Patients with short bowel syndrome have significant fluid losses. This represents a significant management problem, especially in patients with minimal residual intestine. We determined whether clonidine, an alpha2-adrenergic agonist, is effective in decreasing fecal water and sodium (Na) losses in patients with proximal jejunostomy. Eight parenteral nutrition (PN)-dependent subjects (3 men, 5 women), aged 49.9+/-10.2 years, with a residual small bowel length of 71.8+/-152.0 cm that ended in a jejunostomy, were studied. METHODS: Subjects were admitted to the North-western General Clinical Research Center (GCRC) for a 2-day equilibrium period while receiving a self-selected 100 g fat diet with protein 1.5 g/kg/d and 30 kcal/kg/d and 1 L/d of oral rehydration solution. A D-xylose test was performed after an overnight fast. On days 3-5, all stool and urine were collected for volume, weight, fat, nitrogen, energy, sodium, magnesium, potassium, and calcium. Meals were provided in duplicate and the equivalent portions consumed by each patient were analyzed for fluid volume, fat, nitrogen, energy, sodium, magnesium, calcium, and potassium in order to calculate nutrient balances. At the conclusion of the stool and urine collections (day 6), a clonidine (0.3 mg) patch was applied to the shoulder. Subjects were restudied after 1 week. RESULTS: Daily fecal volume and weight were 4.514+/-1.769 L/d and 4394+/-1727 g/d, respectively, at baseline. Five subjects were net "secretors" in that excreted fecal volume exceeded oral intake. Fecal volume decreased by 427+/-562 mL/d (8.9%, p=.07). Fecal weight decreased by 438+/-527 g/d (9.4%, p=.05). Urine volume correspondingly increased by 747+/-1934 mL (18.9%, p=not significant [NS]). The increase in urine output was weakly and negatively correlated with the decrease in fecal volume and weight (r=-0.37 and -0.41, respectively, p=NS). Oral fluid intake decreased slightly from 3.328+/-1.246 L/d baseline to 3.203+/-1.119 L/d with clonidine therapy (-3.8%, p=NS). Fecal Na loss was significantly decreased from baseline (887+/-996 mg/d, 11.2+/-12.3%; p=.036). This was not related to decreased oral Na intake, which actually increased from baseline (3.799+/-2.271 g/d) to 3.933+/-1.314 g/d after clonidine therapy (p=NS). No patient developed hypotension. CONCLUSIONS: Our results show the transdermal administration of clonidine is associated with a modest but clinically significant decrease in fecal output in patients with short bowel syndrome and high-output proximal jejunostomy that require chronic parenteral fluid infusion. This is accompanied by decreased fecal Na loss.     

Plasma choline concentrations in children requiring long-term home parenteral nutrition: a case control study.

BACKGROUND: Low plasma free choline concentration has been associated with elevated serum hepatic aminotransferase concentrations and hepatic steatosis in adults who need home parenteral nutrition (HPN). We sought to determine if plasma free choline is similarly reduced in children who need home total parenteral nutrition (TPN). METHODS: We compared the plasma free choline concentration in 21 children who required long-term HPN with 31 normal controls. Patients had received HPN for 75 +/- 13 (SD) months (range 3-206 months). All control children ingested a normal, mixed, nonvegetarian diet. RESULTS: The mean plasma free choline concentration in the children receiving HPN was significantly lower than normal children (6.6 +/- 4.3 vs 8.0 +/- 2.3 nmol/mL, p = .002). Plasma free choline concentration was correlated with age (r = -0.43, p = .049). Using multiple linear regression analysis for age, sex, and squared age (considered in order to account for possible nonlinearity between choline and age), HPN children showed a steady and significant decline in plasma free choline concentration with increased age at the rate of 0.03 nmol/mL per month. Plasma lipid bound choline concentration did not vary with age. No relationship was seen between either plasma free and lipid bound choline concentration and amount of daily IV lipid infusion. A significant negative correlation was observed between plasma free choline concentration and aspartate aminotransferase (AST) and alanine aminostransferase (ALT) (r = -0.72, p = .04 and r = -0.80, p = .02, respectively). CONCLUSION: Our data support the notion that patients who need long-term HPN without significant enteral feeding have a significant risk for the development of choline deficiency with its associated hepatic dysfunction.     

Parenteral infusion of long- and medium-chain triglycerides and reticuloendothelial system function in man

Previous study demonstrated that patients who received total parenteral nutrition (TPN) with standard intermittent infusion of long chain triglyceride (LCT) at 0.13 g kg-1hr-1 over 10 hr for each of three days showed a significant decline in 99Tc-sulfur colloid (TSC) clearance rate by the reticuloendothelial system (RES). The present studies evaluated eight patients who received the same total lipid dose of LCT infused continuously as in a three-in-one admixture, and another nine patients receiving the same amount of fat as a medium chain triglyceride (MCT)/LCT (75%/25%) emulsion intermittently over 10 hr at 0.13 g kg-1hr-1 for three consecutive days. Patients were given continuous total parenteral nutrition (TPN) comprised of protein, 1.5 g kg-1day-1, and dextrose, 4.5 g kg-1day-1. RES function was examined by measuring the clearance rates of intravenously injected TSC while receiving TPN containing only protein and dextrose, and again after three days of fat infusion. Mean (+/- SEM) clearance rate constants before and after continuous LCT infusion were 0.38 +/- 0.09 and 0.41 +/- 0.08 min-1, respectively, while those before and after intermittent MCT/LCT infusion were 0.50 +/- 0.18 and 0.73 +/- 0.24 min-1, respectively. In contrast to intermittent LCT infusion, the administration of continuous LCT or an intermittent MCT/LCT mixture does not impair TSC clearance by the RES. These findings suggest that condensing the daily period of LCT infusion at standard dosage may exceed the rate of metabolic utilization, resulting in increased fat removal and diminished TSC uptake by the RES.(ABSTRACT TRUNCATED AT 250 WORDS)     

Urogastrone reduces gut atrophy during parenteral alimentation

Urogastrone (UG) exerts trophic effects on the intestine and may play a role in maintaining normal intestinal structure and function. Since administration of nutrients parenterally results in intestinal hypoplasia and hypofunction, the aim of this study was to determine the effects of UG on intestinal structure and function in parenterally fed rats. Central venous catheters were placed into 28 Sprague-Dawley rats. Group I (n = 10) received TPN alone. Group II (n = 8) received TPN and 15 micrograms/day of UG and group III (n = 10) received rat chow ad libitum. The animals that received urogastrone had significantly greater (p less than 0.05) intestinal weight (25.6 +/- 2.5 mg/cm vs 22.6 +/- 3.0 mg/cm), mucosal weight (8.4 +/- 1.4 mg/cm vs 6.2 +/- 0.9 mg/cm), mucosal protein content (6.2 +/- 1.7 mg/cm vs 2.7 +/- 0.6 mg/cm), villous height (427 +/- 27 microns vs 293 +/- 75 microns), crypt cell production rate (14.5 +/- 1.4 metaphases/hr vs 12.3 +/- 0.7 metaphases/hr) and sucrase specific activity (6.5 +/- 2.6 vs 3.7 +/- 2.0) than animals receiving only TPN. However, these parameters remained less than in chow-fed animals. Thus, simultaneous infusion of UG prevents, in part, intestinal hypofunction and hypoplasia which occurs during TPN. This may be due to maintenance of mucosal proliferative activity and brush border enzyme activity.     

Fat oxidation and plasma removal capacity of an intravenous fat emulsion in elderly and young men

OBJECTIVE: We explored metabolic and thermogenic responses to exogenous fat in relation to age as a basis for a rational design of parenteral nutrition in elderly patients. METHODS: Ten healthy elderly men (70-78 y of age, body mass index 21-27 kg/m(2)) and 10 healthy young men (19-45 y of age, body mass index 19-26 kg/m(2)) were studied with a hypertriglyceridemic clamp (primed infusion of a long-chain triacylglycerol emulsion to reach and stabilize at a triacylglycerol concentration of 4 mmol/L for 180 min). Continuous indirect calorimetry was carried out in the basal state and throughout the study period. RESULTS: The infusion rates required to maintain plasma triacylglycerol levels at 4 mmol/L were similar in elderly and young individuals (mean +/- SEM 0.201 +/- 0.027 versus 0.203 +/- 0.014 mmol/min, not significant). Plasma concentrations of free fatty acids and beta-OH-butyrate were higher in the elderly before the infusion and increased in a similar manner in both groups during infusion. Energy expenditure at baseline was higher in the young than in the elderly (79 +/- 2 versus 64 +/- 3 kcal/h; P < 0.001), although the respiratory quotient was similar in the two groups (0.80 +/- 0.01 versus 0.78 +/- 0.01, not significant). During lipid administration there was a similar increase in energy expenditure in the old and young individuals (+9.0 +/- 1.3% versus +6.0 +/- 1.8%, not significant). Lipid infusion resulted in similar increments in fat oxidation in the young and elderly (23.9 +/- 7.0% versus 15.1 +/- 4.9%, respectively, not significant). Plasma lipoprotein lipase activity was almost three times higher in the young than in the elderly subjects (0.23 +/- 0.02 versus 0.65 +/- 0.09 mU/mL, respectively, P < 0.001). During lipid infusion, a similar increment (four- to five-fold) in plasma lipoprotein lipase activity was noted in the two groups. CONCLUSIONS: Elderly healthy men have a similar capacity as young healthy men to clear and oxidize a high triacylglycerol load administered as a hypertriglyceridemic clamp.     

Body composition during nutritional repletion of severely undernourished men.

Body composition was studied in severely undernourished adult male inhabitants of a rural area of Colombia to evaluate the extent and the time course of the changes occurring upon nutritional repletion. During a 45-day basal period on a low (26g/day) protein diet containing adequate calories, body fat depots increased significantly (mean +/- SD = +3.02 +/- 2.9 kg), and there was a significant decrease in cell hydration from 81.8 to 76.4% (-5.4 +/- 9.1%). Upon protein repletion (100 g/day), cell hydration decreased significantly to 71.4%, while body cell mass increased markedly (9.0 +/- 1.1 kg). During protein repletion, muscle cell mass increased significantly (+5.5 +/- 0.6 kg) and rapidly, while the increase in nonmuscle cells (+3.5 +/- 3.8 kg) and specifically in red cell mass lagged behind. With repletion, the changes in the absolute values for plasma volume (+0.4 +/- 0.13 liters) were significant, but those in extracellular fluid volume (-0.7 +/- 1.9 liters) were not. Thus, the major compositional changes observed occurred in the body fat and the body cell mass components; these occurred independently of each other.