摘要:

Fatty acid (FA) composition of membrane phospholipids (PL) and stored triglycerides (TG) from adipose tissue was studied in eight infants aged 1 to 4 months receiving total parenteral nutrition (TPN) since birth. During this period, essential fatty acid (EFA) intake consisted exclusively of soybean oil emulsion administered by intravenous route (Intralipid 20%) representing 301 +/‐ 88 mg/kg/24 hr of linoleic acid and 58 +/‐ 18 mg/kg/24 hr of alpha‐linolenic acid, or 2.3 +/‐ 0.6% and 0.4 +/‐ 0.1%, respectively, of total energy intake. The results were compared with those of eight control infants of the same age receiving orally a normal milk diet with an intake of 660 +/‐ 260 mg/kg/24 hr of linoleic acid and 101 +/‐ 35 mg/kg/24 hr of alpha‐linolenic acid, or 4.5 +/‐ 0.7% and 0.7 +/‐ 0.3%, respectively, of total energy intake. Although their EFA intake was significantly lower (p less than 0.01) and administered only parenterally, after 1 to 4 months the infants receiving TPN still had a membrane phospholipid FA pattern of adipose tissue which was not significantly different from that of normal children of the same age. In stored adipocyte TG, the percentage of linoleic acid was significantly lower (p less than 0.01) in infants receiving TPN. This is probably of nutritional importance as at this stage of life the child builds up its stores of EFA. The proportion of the other fatty acids in adipocyte TG was not significantly modified.

ISSN:0148-6071    

DOI:10.1177/014860719001400142

出版商:SAGE Publications    

年代:1990

数据来源: WILEY

ISSN:0148-6071    

DOI:10.1177/014860719001400403

出版商:SAGE Publications    

年代:1990

数据来源: WILEY

摘要:

This study examined whether the increase in CO2 production (VCO2) and ventilatory demands by carbohydrate loading with different formulas during nighttime enteral feedings could be detrimental in young adult cystic fibrosis patients with moderate to advanced lung disease. Ten patients age 17 to 24 (mean 21.4 years) received 1000 kcal/M2 of a low (Pulmocare), medium (Ensure Plus), and high (Vivonex HN) carbohydrate formula in random order. Eight patients had severe, and two moderate obstructive pulmonary disease; nine used nighttime oxygen therapy. Basal energy expenditure (BEE) without feedings averaged 120% of that predicted by the Harris‐Benedict equation. The metabolic expenditure by indirect calorimetry during nighttime feedings was 25 to 36% greater than the BEE. Oxygen consumption (VO2) increased 21 to 27% during nighttime feedings with no difference between formulas. VCO2 increased 29% for Pulmocare, 46% with Ensure Plus, and 53% with Vivonex HN. The increase in VCO2 with Pulmocare was significantly less than Ensure Plus (p less than 0.05) and Vivonex HN (p less than 0.005). The respiratory quotient (RQ) (VCO2‐/VO2) for Pulmocare (0.88) was the same as the BEE, but increased with Ensure Plus (1.00), and Vivonex HN (1.08). The 41% increase in minute ventilation with Vivonex HN was greater than the 25 to 28% increase observed for Pulmocare and Ensure Plus (p less than 0.05). Transcutaneous oxygen saturation fell no more than 2% with all formulas. PCO2 changed +/‐ 5 torr during enteral feedings with similar changes in any patient with all formulas.(ABSTRACT TRUNCATED AT 250 WORDS)

ISSN:0148-6071    

DOI:10.1177/014860719001400147

出版商:SAGE Publications    

年代:1990

数据来源: WILEY

摘要:

Glutamine is an important amino acid because of its key role in the transfer of both carbon and nitrogen between tissues in the body. Specific tissues are usually associated with either net synthesis or net utilization of glutamine, but the liver plays a central role in glutamine homeostasis, in that it can shift to function in either capacity. This capability, along with the localization of urea biosynthesis in the periportal hepatocytes, focuses attention on the transport mechanisms in hepatocytes for uptake and release of glutamine. Active transport of glutamine by hepatocytes is mediated by a Na+‐dependent activity termed system N, which exhibits a rather narrow substrate specificity mediating uptake of histidine and asparagine as well as of glutamine. This secondary active transport system allows for the net accumulation of glutamine against a concentration gradient and maintenance of intracellular concentrations of glutamine between 4 and 8 mM in the face of a plasma concentration of 0.6 mM. Utilization of the Na+ electrochemical gradient as a driving force ensures that the system N carrier catalyzes a unidirectional transport event favoring the cytoplasm. It is obvious from the glutamine gradient across the plasma membrane that efflux of this amino acid is typically slower than accumulation; measurement of saturable, Na +independent glutamine transport by system L substantiates this proposal. However, it is clear that under certain metabolic conditions the liver represents a source of glutamine for other tissues in the body and net efflux must occur. The system N transport activity in hepatocytes is regulated by hormones such as insulin, glucagon, and glucocorticoids, as demonstrated both in vivo and in vitro. The carrier activity is also responsive to substrate availability, as evidenced by induction of transport activity in vivo in response to high‐protein diets and in vitro by amino acid deprivation of cultured cells. In addition to these long‐term regulatory controls that require de novo protein synthesis, presumably of the carrier itself, system N activity is subject to a rapid modulation by substrate amino acids of systems A and N. This response occurs within minutes of exposure to these amino acids and is protein synthesis independent. It is likely that this complex set of regulatory signals affects system N transport activity in vivo and serves to maintain intracellular levels of glutamine within the hepatocyte, as well as allowing the hepatocyte to monitor and maintain plasma levels in support of whole‐body glutamine metabolism. The exact role of plasma membrane glutamine transport in whole‐body glutamine homeostasis will require extensive experimentation at the cellular and molecular levels. (Journal of Parenteral and Enteral Nutrition14:51S‐55S, 1990)

ISSN:0148-6071    

DOI:10.1177/014860719001400404

出版商:SAGE Publications    

年代:1990

数据来源: WILEY

摘要:

The reliability of shorter nitrogen balance determinations was evaluated in order to facilitate the nutritional assessment of parenterally fed infants. The intraindividual day‐to‐day variations of nitrogen intake, excretion, and retention were analyzed in 23 parenterally fed newborn infants (birth weight: 785–2630 g). Nitrogen retentions measured over 3 consecutive days were highly correlated (r = 0.90–0.96), and the reliability for a single 24‐hr collection was estimated by r1 = 0.93. Nitrogen balance data obtained over a 24‐hr period are reliable for the purpose of clinical investigations, provided the nutrient intake is constant.

ISSN:0148-6071    

DOI:10.1177/014860719001400153

出版商:SAGE Publications    

年代:1990

数据来源: WILEY

摘要:

A fundamental conceptional change in the field of hepatic glutamine metabolism is derived from an understanding of the unique regulatory properties of hepatic glutaminase, the occurrence of glutamine cycling, and the discovery of marked hepatocyte heterogeneities in nitrogen metabolism, with metabolic interactions between differently localized subacinar hepatocyte populations. This change provided new insight into the role of the liver in maintaining ammonia and bicarbonate homeostasis under physiologic and pathologic conditions. Glutamine synthetase is present only in a specialized cell population at the hepatic venous outflow of the liver acinus; these cells act as scavengers for ammonia and probably also for various signal molecules (“perivenous scavenger cell hypothesis”). The function of mitochondrial glutaminase is that of a pH‐ and hormone‐modulated ammonia amplification system that controls carbamoylphosphate synthesis and urea cycle flux in periportal hepatocytes. Not only is hepatic glutamine metabolism essential for maintenance of bicarbonate and ammonia homeostasis, but glutamine itself can act in the liver as a signal modulating hepatic metabolism. This article summarizes some major aspects of hepatic glutamine metabolism, based on previous reviews.(Journal of Parenteral and Enteral Nutrition14:56S‐625, 1990)

ISSN:0148-6071    

DOI:10.1177/014860719001400405

出版商:SAGE Publications    

年代:1990

数据来源: WILEY

摘要:

The indications, methods, and complications of nutritional support of 90 patients admitted with a primary complaint of dysphagia were reviewed. Patients were divided into two groups based on etiology of dysphagia (central neurologic vs local mechanical dysfunction). All patients on admission exhibited marked malnutrition with an average weight loss of 12 +/‐ 9.8% body weight, serum transferrin 165 +/‐ 60.1 mg/dl, and albumin 3.2 +/‐ 0.85 mg/dl. All patients were placed on either enteral (63%) or parenteral (37%) nutrition. Twenty‐seven percent of all patients suffered a complication of nutritional therapy. Patients with nasoenteric tubes had a 10% complication incidence (aspiration or endotracheal placement of tube) resulting in a 30% mortality rate; significantly higher (p less than 0.05) than seen with other modalities. Any form of upper enteric feeding (nasoenteric or gastrostomy) was associated with significantly increased (p less than 0.01) risk of aspiration pneumonia. It is concluded that patients admitted to hospital with dysphagia as the major complaint suffer from severe malnutrition, and that upper gastrointestinal intubation should not be employed for feeding until the dysphagia has resolved.

ISSN:0148-6071    

DOI:10.1177/014860719001400160

出版商:SAGE Publications    

年代:1990

数据来源: WILEY

ISSN:0148-6071    

DOI:10.1177/014860719001400406

出版商:SAGE Publications    

年代:1990

数据来源: WILEY

摘要:

This study was designed to study the effects of small bowel resection on daily urinary excretion patterns, plasma and bone levels of magnesium, phosphorus and calcium in rats on long‐term total parenteral nutrition (TPN). Male Sprague‐Dawley rats weighing 300 to 350 g were randomly divided into two groups with six rats in each group. Control consists of rats whose small intestines were transected but anastomosed. Resected rats had 70% of their small intestine removed. After intestinal resection and transection, rats were infused with a balanced TPN solution for 17 days. Resected rats excreted significantly more calcium than transected rats during the first 10 days of TPN infusion. Peak excretion occurred between day 3 and 4 followed by a trend toward a slightly higher than normal level of calcium excretion between days 10 and 17. Urinary losses of phosphorus and magnesium were not influenced by bowel resection. Plasma and tibia calcium, phosphorus and magnesium levels were not altered. The effects of small bowel resection on urinary calcium loss is specific and our data demonstrate the involvement of gut in regulating urinary calcium excretion and suggest that gut may play a significant role in TPN induced metabolic bone disease.

ISSN:0148-6071    

DOI:10.1177/014860719001400164

出版商:SAGE Publications    

年代:1990

数据来源: WILEY

ISSN:0148-6071    

DOI:10.1177/014860719001400407

出版商:SAGE Publications    

年代:1990

数据来源: WILEY