Biomedical subjects

H S Sitren

Publications and source records attributed to H S Sitren.

32 records · Page 2Linked to original sources

PubMed1978

The effects of meal-feeding at different times of the day on daily changes in serum insulin, gastrin and liver enzymes in the rat.

Restricted feeding at two distinct times of the day was associated with different adaptive responses in rats. Animals meal-fed from 1400 to 1800 hours for 6 days demonstrated feeding-cued circadian rhythms in liver weight and in liver transaminase and lactic dehydrogenase enzyme activities. Daily fluctuations in the levels of blood immunoreactive insulin and gastrin were also found to be cued by food intake. By comparison, rats fed from 0700 to 1100 hours for 6 days exhibited altered liver function and blood immunoreactive gastrin patterns. It is suggested that meal-feeding in rats is associated with certain adaptive responses which are dependent upon the timing of the meal. The observed metabolic alterations consequent to meal-feeding are much more apparent in morning-fed than in afternoon-fed animals.

Adaptation, Physiological↗

PubMed1977

Nitrogen retention in rats fed on diets enriched with arginine and glycine. 1. Improved N retention after trauma.

1. Nitrogen retention was measured in adult rats (250-350 g) subjected to the trauma of hind-leg fracture and given diets with or without arginine plus glycine supplementation. Observations were also recorded on excretion of creatine, creatinine, allantoin, and orotic acid. Liver and skeletal muscle transaminase activities were also determined. 2. When traumatized rats weighing approximately 250 g were given a diet with 200 g casein/kg, supplemented with 20 g arginine and 10 g glycine/kg (EC diet) or a casein diet made isonitrogenous with the EC diet by addition of aspartic acid (C diet), a 60-70% increase in N retention was observed for the first 5 d post-injury for animals consuming the EC diet. A soya-bean (S) diet, isonitrogenous to the diet containing 20% casein, supplemented with arginine and glycine was as effective as the EC diet in promoting significantly better N retention of traumatized rats (350 g) in comparison to rats given the C diet. 3. When the dietary casein content was reduced to 100 g/kg, supplements of 10 g arginine and 5 g glycine or 20 g arginine and 10 g glycine/kg did not improve N retention. It is suggested that both protein quality and protein quantity are important following injury. 4. An increased excretion of creatine was observed in traumatized rats given the high-protein diets supplemented with arginine and glycine. No consistent changes were noted for urine creatinine. 5. 5. Urine allantoin levels remained stable after leg-fracture in rats consuming either the C or EC diets. Differences in the levels of urine orotic acid were found during both the pre- and post-injury periods in rats given the C, EC or S diets. 6. The mechanisms responsible for the improved N retention of traumatized rats consuming the high-protein diets with supplements of arginine and glycine may be related to the role of arginine both as a constituent of muscle tissue and as an intermediate in the urea cycle. 7. In traumatized rats fed the C or EC diets, liver transaminase activity increased whereas the transaminase activity in skeletal muscle decreased. These results support the recent concept that the increased excretion of N following injury arises from diminished reutilization of amino acids by muscle tissue without an acute increase in the rate of muscle catabolism.

Alanine Transaminase↗

PubMed1977

Nitrogen retention in rats fed on diets enriched with arginine and glycine. 2. Effect of diethyl ether anaesthesia on N retention.

1. Adult rats were subjected to a brief period of diethyl ether anaesthesia and were given diets with 200 or 100 g casein/kg with or without arginine plus glycine supplementation in the post-anaesthesia period. Nitrogen retention was measured as well as liver protein content and liver and muscle transaminase activities (L-aspartate aminotransferase (GOT), (EC 2.6.1.1), and L-alanine aminotransferase (GPT)(EC 2.6.1.2). 2. Results demonstrated that anaesthesia-stressed rats consuming the high-protein diet with supplemental arginine and glycine retained twice as much N as did rats given the diet with 200 g casein/kg alone, for the first 5 d post-anaesthesia. 3. Anaesthesia-stressed animals consuming the diets with 100 g casein/kg with or without arginine plus glycine supplementation did not differ from each other in N retention. 4. Liver protein content increased after anaesthesia in rats given the high-protein diets; liver transaminase activity increased, whereas muscle transaminase activity decreased, in animals consuming the high protein diets. 5. Possible mechanisms to account for these results are discussed.

Alanine Transaminase↗

PubMed1975

Comparison of two amino acid solutions for total parenteral nutrition of normal and traumatized hats.

Two amino acid solutions were compared at different levels of nitrogen (N) intake for their effectiveness in promoting N retention in normal and in traumatized rats when given as part of a complete diet under total intravenous feeding conditions. An essential amino acid pattern based on that found in whole egg and one with an essential amino acid pattern based on an egg-potatoe mixture, were equally efficacious in promoting N retention in normal, 300-g rats infused with 75 mg of N and 80 kcal/day. Traumatized rats were in positive N balance on infusions of 400 mg of N/day from either the egg or the egg-protein amino acid solution for the first 5 days postinjury. On day 5 the injured animals showed no significant changes in plasma total protein, albumin, glucose, urea N, total bilirubin, and L-aspartate aminotransferase when compared with each other or with orally fed control rats. The two amino acid solutions were satisfactory sources of amino acids when infused as part of a complete intravenous diet for the purpose of studies in the parenterally fed rat. The results of these studies supported the adequacy of the amino acid requirement data for the adult rat of Nasset (J. Nutr. 61, 555-569, 1957) and of Smith and Johnson (Brit. J. Nutr. 21, 17-27, 1967) but suggested that the NRC values calculated from the data of Benditt et all. (J. Nutr. 40, 335-350, 1950) were too high for several amino acids. An improvement in the surgical cannulation technique is also discussed.

Amino Acids↗

PubMedDate not supplied

Total parenteral nutrition in mice bearing a metastatic carcinoma: tumor growth, metastasis and immunologic parameters.

The role of dietary manipulation of tumor growth, metastasis and immunologic parameters was studied in mice bearing Lewis lung carcinoma. Fourteen days following subcutaneous tumor implant, groups with tumor and their non-tumor bearing counterparts were assigned to one of the following feeding protocols: total parenteral nutrition (TPN), per oral (PO) intake of the parenteral diet, an oral casein diet (CAS), or electrolyte infusion plus the casein diet (ELECT). Intakes of energy and nitrogen were similar among all groups. Mice were killed 12 days later and peritoneal macrophages were tested for phagocytic activity. Tumor growth and metastasis were decreased from both infusion regimens with minimal loss of body weight as compared with casein fed mice. PO mice also showed lower tumor weight but metastasis was as great as in the casein group. Non-tumor-bearing infused mice showed depressed thymic weight, but thymic weight was not further reduced in tumor-bearing infused mice. PO feeding afforded no such protection in the presence of the carcinoma. Splenomegaly was observed in tumor-bearing mice on all regimens, but mice maintained on the parenteral diet demonstrated the largest proportion of macrophages containing nuclear debris. Analysis of free macrophages indicated no effect of diet regimen on non-immune phagocytic activity in both tumor-free and tumor-bearing mice. Possible alteration of splenic macrophage intracellular digestive capacity or phagocytic activity was suggested as a result of TPN.

Animals↗

PubMedDate not supplied

Changes in circadian rhythmicity of liver and serum parameters in rats fed a total parenteral nutrition solution by continuous and discontinuous intravenous or intragastric infusion.

Circadian rhythms were assessed in rats (224-246 grams) receiving either an intragastric (IG) or intravenous (IV) infusion continuously (C), or IG or IV infusions discontinuously (D) from 0000 to 1400 hours daily. A control group was maintained on a stock diet ad libitum. IV- and IG-fed rats were infused with 50 milliliters per day of a solution containing 25% dextrose and 4.25% amino acids plus vitamins and minerals. After 10 to 11 days, groups of rats were killed from each treatment every 6 hours over a 24-hour period. Results showed that IG feeding promoted better growth and nitrogen retention than IV feeding. Rhythm patterns for liver weight, glycogen, and protein content were similar between D-IG and D-IV infused rats. All groups except the D-IV fed rats exhibited fluctuations of serum insulin. A rhythm was not present for serum glucose in C-IV fed rats and a rhythm was also absent for serum albumin in both C-IV and D-IV fed rats. C-IV feeding increased serum glucose and insulin levels and decreased serum albumin levels in comparison to IG feeding. In comparison to the ad libitum-fed, control rats, C-IV or D-IV or IG infusions led to alterations in liver and serum parameters.

Animals↗

PubMedDate not supplied

Total parenteral nutrition in the mouse: development of a technique.

A method for total parenteral nutrition in the mouse was developed using commercially available supplies and equipment. The mouse's inferior vena cava was catheterized and the catheter was exteriorized from the tail. Mice (average body weight 22.5 g) were not tethered but instead were partially restrained by immobilizing the tail to protect the infusion tubing. A solution was formulated to contain 40% dextrose and 4.3% amino acids plus vitamins, electrolytes, and trace elements. It was administered via pump in graded fashion for the first 3 days to allow the mice to adapt, and then at a rate of 8 ml/day thereafter. This volume provided approximately 12 kcal and 54 mg nitrogen per day and was calculated to meet the needs of the mouse fed per os according to guidelines of the National Research Council. During the adaptation period mice lost weight but they were in positive N balance thereafter. At the end of 12 days body weight was not different than at the start, indicating the adequacy of nutrient input. Further, there were no differences in nitrogen balance or body weight in total parenteral nutrition fed mice in comparison with tail-restrained mice given the same solution per os. All mice appeared to tolerate the partial restraint without incidence and showed no untoward side effects. The rationale and validity of this technique is discussed in detail.

Animals↗

PubMedDate not supplied

Total parenteral nutrition in the mouse: body composition and plasma chemistries.

Mice that were maintained in energy and nitrogen (N) balance by total parenteral nutrition (TPN) for 12 days were analyzed for changes in organ weight, carcass and liver N and fat, and plasma glucose, urea N, and total protein. The results are compared with two other groups: (1) PO, which consisted of mice that were given the TPN solution per os in amounts equivalent to the TPN group, and (2) AL, which consisted of mice allowed to consume a stock diet ad libitum. In comparison with group AL, the TPN-fed mice had normal liver, kidney, and lung weights but heavier spleens and hearts. Group PO had an increase in liver weight only. Hepatic lipid content declined in group TPN but increased markedly in PO-fed mice. The latter group also demonstrated a 35% increase in carcass fat whereas it was unchanged in the TPN group. No differences were found in plasma urea N and total protein among the groups but plasma glucose increased 2-fold in group PO. It appears that our technique of parenteral feeding in mice maintains fairly normal body composition and plasma chemistries. However, mice drinking the TPN solution (group PO) exhibited the greatest number of alterations. These results are discussed in relation to differences in route of feeding, diet composition, feeding pattern, and the possible influence of circadian rhythms. The dilemma of choosing appropriate control groups in TPN studies is also discussed.

Animals↗

PubMedDate not supplied

Cost containment using cysteine HCl acidification to increase calcium/phosphate solubility in hyperalimentation solutions.

The purpose of this study was to determine if (1) the calcium/phosphate insoluble product was inversely related to pH [when cysteine HC1 (CH) was added as neonatal supplementation at 0.5 mM/kg/day to hyperalimentation (HAL) solutions] and (2) the potential cost savings to the hospital. The pH of the HAL solutions was adjusted by adding various amounts of CH to the HAL solution. HAL solutions containing 27 mEq of calcium/liter and 30 mEq (15 mM) of phosphate/liter were compounded. Ten-milliliter aliquots were analyzed at 0, 12, 24, and 48 hr. All samples (n = 56) were filtered (0.22 mu), viewed with 7-10,000 X magnification scanning electron microscopy, and qualitatively analyzed with a Philips Energy Dispersive X-Ray Analysis System equipped with a SW9100 Microprocessor. Calcium/phosphate insoluble product was present in the 0-, 12-, 24-, and 48-hr samples from the CH-free solutions. The solutions containing 759 mg (4.17 mM)/liter of CH however, remained free of precipitant. This investigation demonstrated that addition of CH to HAL can foster significant cost containment (projected $82,000/yr tangible hospital savings) by the elimination of current calcium/phosphate separation procedures for neonates on parenteral nutrition.

Calcium↗

PubMedDate not supplied

Nutritional support by intraperitoneal dialysis in the rat: maintenance of body weight with normal liver and plasma chemistries.

A rat model was developed to study intraperitoneal (ip) dialysis as a means of total nutritional support. Rats (200 g) were implanted ip with a catheter device and connected to a rodent infusion assembly. An automated system exchanged 10-ml volumes of a 37 degrees C solution containing 10% dextrose, 2% amino acid solution plus micronutrients. Rats were adapted over 3 days to a schedule of 16 1-hr cycles/day, and continued on this regimen for another 4 days. Rats subjected to this program maintained similar body weight, nitrogen balance, plasma chemistries, and liver tests in comparison to control animals fed per os in isocaloric and isonitrogenous amounts. Efficiency of peritoneal absorption for both glucose and amino acid was 95%. Histological examination of intraabdominal organs revealed only mild inflammation. This model is applicable to studies involving nutritional support via the peritoneal cavity, a technique which may be of value in patients with sensitive fluid balances (cardiac, renal, or pulmonary failure).

Absorption↗

PubMedDate not supplied