A mathematical model of tryptophan metabolism via the kynurenine pathway provides insights into the effects of vitamin B-6 deficiency, tryptophan loading, and induction of tryptophan 2,3-dioxygenase on tryptophan metabolites.

Vitamin B-6 deficiency is associated with impaired tryptophan metabolism because of the coenzyme role of pyridoxal 5'-phosphate (PLP) for kynureninase and kynurenine aminotransferase. To investigate the underlying mechanism, we developed a mathematical model of tryptophan metabolism via the kynurenine pathway. The model includes mammalian data on enzyme kinetics and tryptophan transport from the intestinal lumen to liver, muscle, and brain.

The zinc transporter Zip14 influences c-Met phosphorylation and hepatocyte proliferation during liver regeneration in mice.

Background & Aims: Zinc homeostasis in cells is maintained through tight regulation of zinc influx, efflux, and distribution to intracellular organelles by zinc transporters. The Zrt-Irt-like protein (ZIP) transporters facilitate zinc influx to the cytosol. Expression of the ZIP family member Zip14 can be induced by inflammatory cytokines, which also initiate liver regeneration.

Early-phase neuroendocrine responses and strength adaptations following eccentric-enhanced resistance training.

The purpose of this study was to evaluate the early-phase muscular performance adaptations to 5 weeks of traditional (TRAD) and eccentric-enhanced (ECC+) progressive resistance training and to compare the acute postexercise total testosterone (TT), bioavailable testosterone (BT), growth hormone (GH), and lactate responses in TRAD- and ECC+-trained individuals. Twenty-two previously untrained men (22.1 +/- 0.

Neuroendocrine responses to an acute bout of eccentric-enhanced resistance exercise.

Purpose: The purpose of this study was to compare the total testosterone (TT), bioavailable testosterone (BT), growth hormone (GH), lactate, and ratings of perceived exertion (RPE) responses between a single bout of traditional (TRAD) and eccentric-enhanced resistance exercise (ECC+) of matched training volumes.

Methods: Twenty-two previously untrained males (21.9+/-0.

Pharmacologic levels of dietary arginine in CB6F1 mice increase serum ammonia in the healthy state and serum nitrite in endotoxemia.

Background: Therapeutic or pharmacologic doses of arginine are used to enhance blood flow and immune function despite the lack of dose-response studies and the potential for adverse effects. This study determined the optimal level of oral arginine supplementation required to elevate serum arginine concentrations yet limit adverse effects in healthy and endotoxemic mice.

Methods: Male CB6F1 mice were fed one of the following diets: The standard AIN93G (3 g arginine/100 g of protein) or this diet modified to provide 10 g, 20 g, or 30 g arginine/100 g of protein.

Effects of variation in protein and carbohydrate intake on body mass and composition during energy restriction: a meta-regression 1.

Background: It is unclear whether low-carbohydrate, high-protein, weight-loss diets benefit body mass and composition beyond energy restriction alone.

Objective: The objective was to use meta-regression to determine the effects of variations in protein and carbohydrate intakes on body mass and composition during energy restriction.

Design: English-language studies with a dietary intervention of > or =4200 kJ/d (1000 kcal/d), with a duration of > or =4 wk, and conducted in subjects aged > or =19 y were considered eligible for inclusion.

Synthesis, properties, and intratumoral evaluation of mitoxantrone-loaded casein microspheres in Lewis lung carcinoma.

Smooth, round, uniform bovine casein microspheres of 1-5 and 10-20 microns size were readily prepared by a steric stabilization technique previously developed in this laboratory for synthesis of albumin microspheres. The avid phagocytic uptake of casein and albumin microspheres was demonstrated with fluorescein-labelled microspheres using a macrophage-like mouse myelomonocytic leukaemia cell line. Post-synthesis loading of 25% mitoxantrone was achieved for casein microspheres containing 20% polyglutamic acid.

The effects of glutamine-enriched total parenteral nutrition on tumor growth and host tissues.

The effects of glutamine-enriched total parenteral nutrition (TPN+GLN) were studied in tumor-bearing rats because glutamine can benefit host tissues but also may stimulate tumor growth. Rats were implanted with the methylcholanthrene-induced fibrosarcoma (MCA sarcoma) and were studied when the tumor constituted less than 5% of carcass weight (small tumor) and when the tumor constituted 10% of carcass weight (large tumor). Provision of 20% of TPN protein as glutamine produced a significant increase in the arterial glutamine level and maintained the skeletal muscle intracellular glutamine concentration (2.

Tolerance to long-term feeding of isolated peanut lectin in the rat: evidence for a trophic effect on the small intestines.

Previously we have shown that rats fed a diet containing raw peanut meal as the sole source of protein exhibited alterations in enzyme activity and composition of certain organs. To determine the effects of isolated peanut lectin on body growth and on the intestines, experiments were carried out in weanling, male, Sprague-Dawley rats fed a casein diet incorporated with purified peanut lectin at three levels, 0.004, 0.

Inhibition of tumor growth and metastasis by chronic intravenous infusion of prostaglandin E1.

The role of prostaglandins and their synthesis inhibitors in malignant disease is undefined. The following studies were done to determine the effects of continuous intravenous prostaglandin E1 (PGE1) or a prostaglandin synthesis inhibitor, indomethacin, on tumor growth and metastasis in mice bearing Lewis lung carcinoma. Male B6D2F1 mice underwent tumor implantation in the right axilla on day 0.

Differential role of prostaglandin E1 on tumor metastasis.

Previous studies from our laboratory have shown that intravenous (iv) infusion of pharmacologic doses of prostaglandin E1 (PGE1) inhibits "spontaneous" metastases in mice bearing Lewis Lung carcinoma (LLC). This study was done to determine the effect of iv PGE1 on "artificial" metastases. Male hybrid mice (20 g) underwent iv catheterization and were begun on continuous infusions of either PGE1 at 10 micrograms/kg/min or 0.

Correlation of estrogen, progesterone, and androgen receptors in breast cancer.

Breast cancer was induced in female Holtzman rats by intragastric administration of 7,12-dimethylbenz[a]antracene (DMBA). At tumor maturity, biopsies of viable tissue were obtained, frozen, and then assayed for estrogen, progesterone, and androgen receptor content. By simple linear regression analysis, progesterone receptor levels significantly correlated with both estrogen and androgen receptor levels, whereas estrogen and androgen receptor levels did not correlate with each other.

Lability of steroid hormone receptors following devascularization of breast tumors.

Ischemia may invalidate hormone-receptor analyses. This study determined the effects of progressive ischemia on steroid hormone-receptor analyses. Breast cancer was induced in 50- to 60-day-old female Holtzman rats by intragastric administration of 25 mg of 7,12-dimethylbenz[a]anthracene.

Partial hepatectomy decreases pancreatic parenchymal enzyme activity.

In previous studies of liver regeneration following partial hepatectomy (PH) in rats, we noted a decrease in serum amylase activity. The present study was carried out to determine if the decrease in serum amylase following PH corresponds to a decrease in pancreatic parenchymal exocrine enzyme activity. Male Wistar rats (275 g) underwent either 60% PH or sham laparotomy (SL).

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.

Comparison of glucose and glucose plus lipid as caloric sources in parenterally fed rats.

This study investigated the etiology of fat infiltration of the liver during total parenteral nutrition. We measured the content of liver lipids, serum lipids, liver lipogenic enzymes, rates of in vivo fatty acid synthesis, and carcass composition in rats during continuous intravenous (iv) and intragastric (ig) feeding of two diets containing either 100% glucose or 75% glucose-25% lipid (20% Intralipid). Two groups of orally (O) fed rats were given solid diets similar to either the glucose or glucose-lipid solution in energy and nitrogen content.

Dosage form and formulation effects on the bioavailability of vitamin E, riboflavin, and vitamin B-6 from multivitamin preparations.

The effects of formulation factors and pharmaceutical dosage form on the bioavailability of RRR-alpha-tocopherol (d-alpha-tocopherol), riboflavin, and pyridoxine hydrochloride were studied after administration of two capsule formulations and a tablet to 12 normal humans. Absorption of RRR-alpha-tocopherol was increased from the Aquabiosorb soft elastic gelatin (SEG) capsule formulation compared with the modified standard-SEG capsule and the commercial tablet. There were no significant differences in bioavailability of riboflavin and pyridoxine hydrochloride between the SEG formulation and the tablet albeit a trend toward consistent absorption was seen from the SEG formulation.

Causative factors for decreased pulmonary metastasis in parenterally fed mice.

Total parenteral nutrition (TPN) with fat and/or glucose as the caloric source is associated with a decrease in pulmonary metastasis in mice bearing subcutaneously implanted Lewis lung carcinoma. Five groups of white mice bearing Lewis lung carcinoma were assigned to receive various isocaloric and isonitrogenous oral and parenteral feedings: TPN, utilizing all nonnitrogen energy from glucose; per os, utilizing all nonnitrogen calories from glucose; electrolyte, utilizing nonnitrogen calories provided from a balanced casein diet and receiving an isovolemic infusion of electrolytes in the same composition as the TPN formula; 1/4 normal saline, also consuming the casein diet and receiving an isovolemic infusion of 1/4 normal saline; and an oral casein control (CON) without infusion. Results showed that there were no significant differences in tumor volume changes or tumor doubling time among the groups.

Decreased lung metastasis and tumor growth in parenterally fed mice.

The influence of alternate forms of nutritional support on primary tumor growth rate, tumor DNA synthesis rate, and number of lung metastases was examined in Swiss mice bearing subcutaneously implanted Lewis lung carcinoma (LLC). From Day 14 through 22 postimplant, mice were fed by continuous intravenous infusion of dextrose/amino acid (TPN), were offered the same solution from a feeding bottle (PO), were offered a casein-based, solid diet (CASEIN), or were infused with an electrolyte (ELECT) solution while energy and nitrogen were provided from the casein diet. Tumor weight and doubling time were decreased in the PO group compared to CASEIN; however, host weight decreased by 22% in the PO group.

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.

Parenteral handling precaution: particulate introduction resulting from needle sheath contamination.

The purpose of this in vitro experiment was to determine if inadvertent needle cap nicking would introduce particulate contamination. After a preliminary observation (n = 21), a more thorough confirmatory experiment (n = 28) was performed. Twenty-four of 28 needles were contaminated before, and 18 of 28 needles after, entry into a Latex injection port; 5 of these 18 needles remained contaminated post sterile water injection and withdrawal from the port.