摘要:

The effect of dietary nucleotides upon hepatic growth and composition was examined in weanling mice. For 5 weeks, mice were fed either Purina™ Rat Chow, a nucleotide‐free diet (NT−), a nucleotide‐free diet supplemented with a mixture of five nucleotides (0.21% w/w), (NT+) or a nucleotide‐free diet supplemented with adenosine 5′‐monophosphate (0.0425% w/w) (NTA). Hepatic cholesterol and lipid phosphorous were significantly higher, whereas liver weight (expressed as a percentage of body weight), and glycogen were lower in animals fed NT−vsall other groups. NTA‐fed animals presented a greater contrast to the NT−group than did animals fed the mixture of nucleotides. Liver fatty acid composition and distribution of phospholipid subclasses were not affected by dietary nucleotide supplementation. Dietary nucleotide supplementation in weanling mice affects hepatic growth and composition; adenosine 5′‐monophosphate may play a unique role in these effects. (Journal of Parenteral and Enteral Nutrition18:62–66, 1994)

ISSN:0148-6071    

DOI:10.1177/014860719401800162

出版商:SAGE Publications    

年代:1994

数据来源: WILEY

摘要:

Intestinal access for enteral nutrition can be achieved by spontaneous intestinal nasogastric tube passage or by endoscopic, fluoroscopic, or surgical placement methods. Each of these methods has limitations that may compromise clinical utility. pH‐sensing nasointestinal feeding tubes allow active placement with minimal equipment and expertise; however, this method requires an acidic gastric pH. We sought to determine whether antiulcer regimens used at our institution would preclude intestinal pH‐sensing tube placement. Twenty‐five patients had 25 (81%) successful intestinal placements in 31 attempts. Observed pH values and calculated pH changes were compared within and between successful and unsuccessful groups by using a Student'sttest. Initial, lowest, and final pH values did not differ significantly between groups. The pH change initial‐to‐lowest (4.7 ± 0.18vs3.6 ± 0.59,p<.03) and lowest‐to‐final (5.0 ± 0.18vs3.0 ± 0.47,P<.0001) differed significantly between groups, whereas the pH change initial‐to‐final did not. Cost analysis of endoscopic ($782), fluoroscopic ($341 to $382), spontaneous ($167 to $212), and pH‐sensing ($162) methods revealed 3% to 79% savings when the pH‐sensing placement method was used. We conclude that the antiulcer therapies used in our patient population did not preclude intestinal pH‐sensing tube placement. If the pH changes from initial‐to‐lowest and lowest‐to‐final were greater than 4, successful intestinal placement occurred in 91% of attempts. Finally, the method was cost‐effective at our institution. (Journal of Parenteral and Enteral Nutrition18:67–70, 1994)

ISSN:0148-6071    

DOI:10.1177/014860719401800167

出版商:SAGE Publications    

年代:1994

数据来源: WILEY

摘要:

Infections pose a major problem in patients receiving total parenteral nutrition. Controversy continues concerning the effect of catheter type (triple‐, double‐, single‐lumen, or pulmonary artery), insertion site (subclavian, internal jugular, or femoral vein), and the incidence of catheter‐related infections. We retrospectively studied multi‐lumen catheter use for total parenteral nutrition over a 6‐month period in 192 patients, a total of 3334 catheter days. Nonintensive care unit catheters were inserted by the Nutrition Support Service, and intensive care unit catheters were inserted by the intensive care unit staff. All catheters were cared for using Nutrition Support Service protocols, with multi‐lumen catheters changed every 7 to 10 days and pulmonary artery catheters changed every 4 days. Infections were determined by semiquantitative cultures (>15 colonies/plate). The incidence of infections for triple‐lumen catheters was 5 (subclavian), 17 (internal jugular), and 36% (femoral) respectively; total infection rate for triple‐lumen catheters was 10%. Infection rates for pulmonary artery catheters were 4 (subclavian), and 6% internal (jugular site), respectively, the overall infection rate was 5%. There were no differences in infection rates at any site based on catheter type; however, when triple‐lumen catheter sites were compared, the differences were significant (p<.001vssubclavian, χ2). Catheter duration was 7.8 days (subclavian), 7.3 days (internal jugular), and 4.6 (femoral) days. These data suggest that the use of multi‐lumen catheters for total parenteral nutrition is safe, that there is a benefit associated with the subclavian route, and that the femoral site should be avoided. (Journal of Parenteral and Enteral Nutrition18:71–74, 1994)

ISSN:0148-6071    

DOI:10.1177/014860719401800171

出版商:SAGE Publications    

年代:1994

数据来源: WILEY

摘要:

Prolonged bowel rest and total parenteral nutrition lead to gastrointestinal mucosal atrophy. The possibility that enteral diets of varying composition could have a beneficial effect in reversing total parenteral nutrition‐associated gut atrophy was investigated. A group of male Sprague‐Dawley rats were randomized to receive TPN for 10 days, followed by 10 days of elemental or regular food. The effects of these diets on body mass, gastro‐intestinal index (intestinal weight divided by body weight), mucosal incorporation of titrated thymidine, and intestinal villi length were compared. Significant gut villi atrophy and use of gut weight occurred in rats receiving TPN and bowel rest compared with the fed control group. These changes were significantly reversed by elemental diets, but not by rat food diets. We conclude that elemental diets may enhance gut recovery after prolonged TPN and bowel rest in a rat model. (Journal of Parenteral and Enteral Nutrition18:75–78, 1994)

ISSN:0148-6071    

DOI:10.1177/014860719401800175

出版商:SAGE Publications    

年代:1994

数据来源: WILEY

摘要:

A case is presented of the fracture and embolization of a peripherally inserted central venous catheter. This novel complication is discussed in the context of patients in alternate care settings with emphasis on retrieval of the embolized catheter fragment, morbidity of catheter embolization, and precautions against inadvertent fracture in the home care setting. (Journal of Parenteral and Enteral Nutrition18:79–80, 1994)

ISSN:0148-6071    

DOI:10.1177/014860719401800179

出版商:SAGE Publications    

年代:1994

数据来源: WILEY

摘要:

Long‐term central venous access catheters generally require creating a subcutaneous tunnel to minimize infectious complications and secure the catheter to the chest wall. Many techniques for this procedure have been reported. We describe the use of a uterine sound to create the subcutaneous tunnel. (Journal of Parenteral and Enteral Nutrition18:81–82, 1994)

ISSN:0148-6071    

DOI:10.1177/014860719401800181

出版商:SAGE Publications    

年代:1994

数据来源: WILEY

摘要:

The purpose of this study was to elucidate the mechanisms responsible for the restricted position‐dependent expression of the Glut‐1 glucose transporter in the plasma membrane to a small population of parenchymal cells in rat liver. On the basis of earlier studies in which the erythroid/brain (Glut‐1) glucose transporter isoform was detected by immunofluorescence only in the last two hepatocytes surrounding the terminal hepatic venule,1investigators in Jorge Gumucio's laboratory at the University of Michigan sought to determine the molecular basis for the observation. To study the expression of this transporter in individual hepatocyte populations (periportal vs perivenous), the authors used the digitonin/collagenase cell isolation method. Their conclusions rest on two assumptions: (1) the modified digitonin/collagenase method of hepatocyte isolation used in the studies adequately separates periportal and perivenous cells, and (2) the Glut‐1 protein distribution in isolated hepatocyte populations reflects the normal localization in liver tissue. The authors go to great lengths to demonstrate that these two assumptions hold true.Hepatocyte populations enriched in perivenous or periportal cells were obtained by the digitonin/collagenase method2,3in which digitonin is perfused either antegrade or retrograde to selectively destroy periportal or perivenous cells, respectively, followed by the subsequent isolation of the remaining population of cells by collagenase digestion. In this report, the authors describe a refinement of the original technique in which an additional Percoll gradient step is used to separate damaged from healthy hepatocytes. Once the damaged hepatocytes were isolated, hepatocyte population purity was assessed by Northern blot analysis using albumin, P450 isozymes IIB1 and IIB2, and glutamine synthetase probes. The acinar (cell plate) localization of each of these gene products is well established, and results demonstrated population purity, with glutamine synthetase messenger RNA (mRNA) present in the perivenous isolates and absent in periportal isolates. Thus, the first assumption was correct. Concurrently, Glut‐1 mRNA was probed and, surprisingly, found to be present in approximately equal levels in both cell populations despite the restricted plasma membrane localization to only the terminal two perivenous hepatocytes.To ensure that the second assumption held true, the authors used laser scanning confocal microscopy to verify that the Glut‐1 transporter was expressed in the plasma membrane only in the one or two hepatocytes surrounding the sinusoidal outflow. Diffuse intracellular fluorescence that was more accentuated near the plasma membrane was detected in the periportal cells in the liver slices, an observation that would corroborate both the presence of Glut‐1 mRNA in periportal cells and the subsequent subcellular localization of the Glut‐1 protein to the Golgi fraction. Additionally, because Glut‐1 has been shown to be a “stress” protein, the authors demonstrated that the differential localization of Glut‐1 was not a cell isolation‐induced artifact by measuring the levels of glucose‐regulated protein 78 in parallel with Glut‐1. They also ruled out a contribution to Glut‐1 detection by bile duct cell contamination by the absence of cytokeratin 19 in isolated parenchymal cell populations. Collectively, these observations supported the second assumption that the protein pattern for Glut‐1 observed in isolated hepatocyte populations reflects that seen in native liver tissue.Finally, by probing Western blots of subcellular fractions from each of the populations with anti‐Glut‐1 antibodies, the authors confirmed the data from the laser‐scanning confocal microscopy. The Glut‐1 protein was detected in the plasma membrane fraction only in perivenous cells, whereas it was restricted to the low‐density microsomal (Golgi‐enriched) fraction (200,000 x g pellet) in periportal cells. The authors conclude that the differential insertion (ie, a posttranslational event) of the Glut‐1 transporter into the plasma membrane of only the terminal two perivenous hepatocytes is responsible for the immunohistologic observations in previous studies.

ISSN:0148-6071    

DOI:10.1177/014860719401800183

出版商:SAGE Publications    

年代:1994

数据来源: WILEY

摘要:

In this study, Ko et al determined whether L‐glutamine (GLN) is essential for epidermal growth factor (EGF)‐stimulated enterocyte proliferation in anin vitrocell culture system by using the nontransformed rat small intestinal crypt cell line IEC‐6. In addition, specific mitogenic actions of EGF that require GLN were investigated.IEC‐6 cells were maintained in monolayer culture by incubation in standard culture medium (Dulbecco's minimum essential medium) containing 5% bovine serum, grown to quiescence, and then incubated in serum‐free Dulbecco's minimum essential medium containing 0.1 to 0.2 mmol/L GLN for 36 hours (as in almost all other cell culture systems, GLN is required to prevent IEC‐6 cell death in serum‐free medium). Cells were then stimulated with a previously determined maximal trophic dose of EGF (20 ng/mL) plus varying concentrations of L‐GLN (0 to 10 mmol/L) added to the culture medium. Under these conditions, DNA, RNA, and protein synthesis were quantitated over time (0 to 30 hours) by using tritiated thymidine, tritiated uridine, and14C‐leucine, respectively. Cell number was determined after 72 hours of treatment with varying amounts of added GLN with or without EGF. Total RNA was isolated from the EGF/GLN‐treated cells in other experiments for determination of messenger RNA (mRNA) levels of the “early response” proto‐oncogene transcription factorszif268, jun‐B,andc‐mycby Northern blotting.GLN was required for EGF‐stimulated DNA synthesis in IEC‐6 cells. Thus, EGF (20 ng/mL) added to quiescent cells without additional GLN (ie, not more than the 0.1 mmol/L required to prevent cell death) did not stimulate DNA synthesis at any time from 0 to 30 hours of incubation. However, addition of a larger amount of GLN (1.0 mmol/L) to EGF significantly stimulated DNA synthesis beginning 9 hours after incubation, and this effect on DNA synthesis steadily increased over time. The increased DNA synthesis in cells treated with EGF was related to L‐GLN dose; stimulation occurred only after 0.3 mmol/L GLN. In contrast, DNA synthesis was not stimulated significantly by addition of increasing amounts of GLN alone to the medium and was maximal at 1 to 3 mmol/L GLN. The requirement for GLN under these conditions was amino acid specific and stereospecific, inasmuch as D‐GLN, L‐arginine, and L‐alanine were not effective in enhancing EGF‐stimulated DNA synthesis.The addition of 1 mmol/L GLN to EGF also significantly increased RNA and protein synthesis beginning 3 hours after incubation. Without the addition of L‐GLN to standard media, EGF‐induced protein synthesis was reduced 80% and RNA synthesis 70%. Cell growth studies revealed that GLN added at a dose of either 1.0 or 10 mmol/L significantly increased (~fourfold) cell number compared with control cells (without EGF in standard medium containing 0.1 mmol/L GLN) and cells treated with EGF alone in standard medium.Northern analysis for mRNA levels of the proto‐oncogene transcription factorszif268, jun‐B,andc‐mycshowed significantly increased mRNA expression of all three genes after 30 minutes of exposure to EGF; however, these responses were similar with or without supplemental L‐GLN. Interestingly, mRNA levels forlf268, jun‐B,andc‐mycremained persistently elevated at 2 hours after treatment with EGF alone, but levels decreased to a variable degree with EGF plus GLN at this time point.

ISSN:0148-6071    

DOI:10.1177/014860719401800184

出版商:SAGE Publications    

年代:1994

数据来源: WILEY

摘要:

The perioperative use of total parenteral nutrition (TPN) as an adjunct to surgical treatment of severely nutrient‐depleted patients is appropriate. Potentially deleterious effects of TPN on the gut have been examined with regard to atrophy and gut mucosal barrier function.1The specific alterations in nutrient transport, an energy‐dependent luminal mechanism, have not, however, been clearly defined. Active transport of specific amino acids across the brush‐border membrane is facilitated by a number of carriers, some of which are sodium dependent.2The maintenance of a sodium gradient requires energy; it is hypothesized that down‐regulation of brush‐border membrane transport should result from periods of low availability of luminal nutrients. If specific nutrients are physiologically more important, transport would be maintained.To study these changes, adult patients who were to undergo intestinal surgery were randomized to immediate operation or a 7‐day period of bowel rest with calorie and protein needs met by TPN. At celiotomy, segments of distal ileum were obtained and mucosa scraped for the preparation of brush‐border membrane vesicles. The brush‐border membrane vesicles were coincubated with labeled amino acids in the presence or absence of sodium. By determining the time course of uptake into vesicles, the maximum velocity as well as the affinity of the specific receptor can be determined. By expressing this data as an Eadie‐Hofstee transformation, the number of receptor sites can be extrapolated. Specific nutrients examined included glutamine (GLN), methyl‐d‐amino isobutyric acid (a system A analog), alanine, arganine, and glucose.A period of no oral nutrition, even with adequate parenteral nutrition support, caused down‐regulation in the number of receptors for alanine, arginine, leucine, and glucose. GLN transport, however, was maintained. In a single patient in whom jejunum was available, nutrient uptake was decreased across the board; however, GLN was the least diminished.

ISSN:0148-6071    

DOI:10.1177/014860719401800120

出版商:SAGE Publications    

年代:1994

数据来源: WILEY

ISSN:0148-6071    

DOI:10.1177/014860719401800122

出版商:SAGE Publications    

年代:1994

数据来源: WILEY