Walker 256 tumor-bearing rats demonstrate altered interstitial cells of Cajal. Effects on ICC in the Walker 256 tumor model.

BACKGROUND: Cachexia is a significant problem in patients with cancer. The effect of cancer on interstitial cells of Cajal (ICC) and neurons of the gastrointestinal tract have not been studied previously. Although supplementation with L-glutamine 2% may have beneficial effects in cancer-related cachexia, and be protective of ICC in models of oxidative stress such as diabetes, its effects on ICC in cancer have also not been studied. METHODS: Twenty-eight male Wistar rats were divided into four groups: control (C), control supplemented with L-glutamine (CG), Walker 256 tumor (WT), and Walker 256 tumor supplemented with L-glutamine (WTG). Rats were implanted with tumor cells or injected with saline in the right flank. After 14 days, the jejunal tissues were collected and processed for immunohistochemical techniques including whole mounts and cryosections and Western blot analysis. KEY RESULTS: Tumor-bearing rats demonstrate reduced numbers of Myenteric ICC and deep muscular plexus ICC and yet increased Ano1 protein expression and enhanced ICC networks. In addition, there is more nNOS protein expressed in tumor-bearing rats compared to controls. L-glutamine treatment had a variety of effects on ICC that may be related to the disease state and the interaction of ICC and nNOS neurons. Regardless, L-glutamine reduced the size of tumors and also tumor-induced cachexia that was not due to altered food intake. CONCLUSIONS & INFERENCES: There are significant effects on ICC in the Walker 256 tumor model. Although supplementation with L-glutamine has differential and complex effects of ICC, it reduces tumor size and tumor-associated cachexia, which supports its beneficial therapeutic role in cancer.

Swimming performance of the freshwater neotropical fish: Pimelodus maculatus Lacepède, 1803.

The present study used fixed and increasing velocity tests in an experimental apparatus based on Brett's respirometer to examine prolonged and sustained speeds of the "mandi-amarelo", Pimelodus maculatus. When comparing the curves of critical speed versus total length between the mandi and the sockeye salmon Oncorhynchus nerka, it is observed that for an equal total length, the mandi presents a greater speed, probably due to water temperature differences. The sustained speed for the species was estimated in 5 lengths per second and the percentage of fatigued fish within time in a certain velocity was established. The data raised for the mandi represents an important contribution to the improvement of the handling of the species, providing guidance and criteria for designing several structures, such as fishways, fish screens and guidance systems.

Swimming performance of the freshwater neotropical fish: Pimelodus maculatus Lacepède, 1803 / Capacidade natatória da espécie neotropical de água doce: Pimelodus maculatus Lacepède, 1803

The present study used fixed and increasing velocity tests in an experimental apparatus based on Brett's respirometer to examine prolonged and sustained speeds of the "mandi-amarelo", Pimelodus maculatus. When comparing the curves of critical speed versus total length between the mandi and the sockeye salmon Oncorhynchus nerka, it is observed that for an equal total length, the mandi presents a greater speed, probably due to water temperature differences. The sustained speed for the species was estimated in 5 lengths per second and the percentage of fatigued fish within time in a certain velocity was established. The data raised for the mandi represents an important contribution to the improvement of the handling of the species, providing guidance and criteria for designing several structures, such as fishways, fish screens and guidance systems.

No presente estudo, foram utilizados testes de velocidade fixa e progressiva em um aparato experimental baseado no respirômetro de Brett, para examinar as velocidades prolongada e sustentável do mandi-amarelo, Pimelodus maculatus. Quando comparadas as curvas de velocidade crítica versus o comprimento do corpo entre o mandi e o salmão Oncorhynchus nerka, é observado que, para um mesmo comprimento, o mandi apresenta velocidades superiores, provavelmente devido a diferenças na temperatura da água. Foram estimadas a velocidade sustentável da espécie em cinco comprimentos por segundo e a porcentagem de peixes fatigados ao longo do tempo em uma dada velocidade estimada. Os dados obtidos para o mandi representam uma importante contribuição para o manejo da espécie, provendo critérios de projeto para a construção de estruturas como mecanismos de transposição e sistemas de proteção e orientação.

Glycogen levels and glycogen catabolism in livers from arthritic rats.

Hepatic glycogen catabolism and glycogen levels in rats with chronic arthritis were investigated. At 9:00 a.m., the hepatic glycogen contents of ad libitum fed arthritic and normal rats were 225.5+/-17.7 and 332.1+/-28.6 micromol glucosyl units x (g liver)(-1), respectively. Food intake of arthritic and normal rats was equal to 100.1+/-6.7 and 105.0+/-3.1 mg x (g body w)(-1) x (per 24 h)(-1), respectively. In isolated perfused livers from normal and arthritic rats the rates of glucose, lactate and pyruvate release were the same when substrate- and hormone-free perfusion was performed. During an infusion period of 20 min glucagon caused an increment in glucose release of 35.3+/-4.7 micromol x (g liver)(-1) in livers from arthritic rats; in the normal condition the corresponding increment was 69.6+/-5.7 micromol x (g liver)(-1). Lactate and pyruvate productions (indicators of glycolysis) were diminished by glucagon in livers from normal rats; in the arthritic condition an initial stimulation was found, followed by a slow decay, which did not result in significant inhibition at the end of the glucagon infusion period (20 min). The actions of cAMP and dibutyryl-cAMP were similar to those of glucagon. It was concluded that livers from arthritic rats show an impaired capacity of releasing glucose under the stimulus of glucagon. This can be partly due to the lower glycogen levels and partly to a smaller capacity of inhibiting glycolysis. Reduction in glycogen levels was not associated with reduction in food intake or failure in the energetic state of the hepatic cells. These changes in glycogen metabolism may be related to reduced gluconeogenic capacity of the livers and/or to production of inflammatory mediators observed in the arthritis disease.

Transport of cyclic AMP and synthetic analogs in the perfused rat liver.

The purpose of the present work was to investigate the transport of cyclic AMP (cAMP) and analogs in the rat liver. The experimental system was the isolated once-through perfused liver. Transport was measured by employing the multiple-indicator dilution technique. The single-pass recovery of tracer [(32)P]cAMP was equal to 94.4 +/- 1. 4%; no significant extracellular transformation of cAMP occurred during a single passage. The unidirectional influx rates of dibutyryl-cAMP were a saturable function of its concentration, with K(m) = 72.75 +/- 9.24 microM and V(max) = 0.464 +/- 0.026 micromol min(-1) (mL cellular space)(-1). The unidirectional influx rates of cAMP were much lower than those of dibutyryl-cAMP and were a linear function of the concentration (up to 100 microM). The transfer coefficient for influx (k(in)) was equal to 0.860 +/- 0.058 mL min(-1) (mL extracellular space)(-1). cAMP inhibited the influx of dibutyryl-cAMP; the IC(50) was 0.83 mM. The following series of increasing unidirectional influx rates was found: cAMP < monobutyryl-cAMP approximately 2-aza-epsilon-cAMP < rp-cAMPS approximately sp-cAMPS < 8-Br-cAMP approximately dibutyryl-cGMP approximately 8-Cl-cAMP < O-dibutyryl-cAMP. There was no precise correlation between the rates of influx of the various cyclic nucleotides and their lipophilicity. It was concluded that the penetration of cAMP and its analogs into the liver cells was a facilitated process. Lipophilicity was not the only factor determining the rate of transport. The transformation of dibutyryl-cAMP was limited by both transport and activity of the intracellular enzymic systems. The intracellular transformation of exogenous cAMP, however, was limited by the transport process.

Modeling the transformation of exogenously supplied cAMP in the perfused rat liver.

A kinetic model describing the behavior of extracellularly supplied cAMP in the perfused rat liver was derived and compared with experimental data. The model was based on the following conditions and assumptions: a) labeled cAMP is being constantly infused (step input); b) permeation of the cell membrane is an essentially irreversible step (k(in) as transfer coefficient); c) the adenine moiety of cAMP incorporates into a nucleotide pool (km1 as transformation coefficient), which cannot permeate the cell membrane; d) the adenine moiety of cAMP can be transferred from the nucleotide pool to a nucleoside + free base pool (km2 as transformation coefficient), which is able to permeate the cell membrane (k(ef) as transfer coefficient). These events were described by a series of differential equations for which an analytical solution was obtained. Total cellular incorporation of label derived from [3H]cAMP was measured in the isolated perfused rat liver. The equations of the model were fitted to these experimental data by means of a least-squares procedure. In the fitting procedure the previously determined k(in) value (0.55 ml min(-1) ml cellular space(-1)) was used. The model is able to describe the experimental data (correlation coefficient = 0.993 +/- 0.008) with km1, km2 and k(ef) values of 17.11, 0.0948 and 1.385 min(-1), respectively. Simulations revealed the following sequence of decreasing intracellular pool sizes: nucleotide pool > nucleoside + free base pool > intracellular cAMP. The intracellular cAMP concentrations correspond to only 3.2% of the extracellular ones. This low proportion explains why it was generally difficult to detect cAMP in the cell space when this compound was added to an isolated cell system. The model and the parameters determined in the present work can be used to predict intracellular cAMP concentrations in the perfused liver for specific extracellular concentrations.

Gluconeogenesis in the liver of arthritic rats.

The gluconeogenic response in the liver from rats with chronic arthritis to various substrates and the effects of glucagon were investigated. The experimental technique used was the isolated liver perfusion. Hepatic gluconeogenesis in arthritic rats was generally lower than in normal rats. The difference between normal and arthritic rats depended on the gluconeogenic substrate. In the absence of glucagon the following sequence of decreasing differences was found: alanine (-71.8 per cent) reverse similarglutamine (-71.7 per cent)>pyruvate (-60 per cent)>lactate+pyruvate (-44.9 per cent)>xylitol (n.s.=non-significant) reverse similarglycerol (n.s.). For most substrates glucagon increased hepatic gluconeogenesis in both normal and arthritic rats. The difference between normal and arthritic rats, however, tended to diminish, as revealed by the data of the following sequence: alanine (-48.9 per cent) reverse similarpyruvate (-47.6 per cent)>glutamine (-33.8 per cent)>glycerol (n.s.) reverse similarlactate+pyruvate (n.s.) reverse similarxylitol (n.s.). The causes for the reduced hepatic gluconeogenesis in arthritic rats are probably related to: (a) lower activities of key enzymes catalyzing most probably steps preceding phosphoenolpyruvate (e.g. phosphoenolpyruvate carboxykinase, pyruvate carboxylase, etc. ); (b) a reduced availability of reducing equivalents in the cytosol; (c) specific differences in the situations induced by hormones or by the individual substrates. Since glycaemia is almost normal in chronically arthritic rats, it seems that lower gluconeogenesis is actually adapted to the specific needs of these animals.

The role of hemodynamics in the action of diltiazem on hepatic fatty acid metabolism.

The hemodynamic effects of diltiazem in the liver are strictly Ca2+ -dependent Consequently, Ca2+ -free perfusion can be used for investigating the metabolic effects of diltiazem without interference by hemodynamics. Livers were perfused with Krebs/Henseleit-bicarbonate buffer (pH 7.4). For performing Ca2+ -free perfusion the cation was omitted from the perfusion fluid and the cellular pools were exhausted by repeated phenylephrine infusions. Three conditions were investigated with and without Ca2+ : (1) substrate-free perfusion fluid; (2) 0.3 mM [1-(14)C]octanoate infusion; (3) 0.3 mM [1-(14)C]palmitate infusion. The following results were obtained: 1. Oxygen uptake stimulation caused by octanoate and palmitate was abolished by 500 microM diltiazem in the presence of Ca2+; in the absence of Ca2+ there was no inhibition (octanoate) or it was much smaller (palmitate); 2. The 14CO2 production was inhibited in the presence of Ca2+; in the absence of Ca2+ there was no inhibition (palmitate) or even stimulation (octanoate). 3. Ketogenesis from endogenous sources, from palmitate and from octanoate was inhibited by diltiazem in the presence as well as in the absence of Ca2+. The beta-hidroxybutyrate/acetoacetate ratio was diminished in the presence and in the absence of Ca2+ . It was concluded that inhibition of fatty acid oxidation by diltiazem depends partly on the Ca2+ -dependent hemodynamic effects and partly on a Ca2+ -independent action on some enzymatic system.

[First results of varietal comparison and nitrogen fertilization of rapeseed in Italy (author's transl)]. / Primi risultati di confronto varietale e di concimazione azotata del colza in Italia

Some experiments of varietal comparison of various cultivars of rapeseed were carried out, determining the productivity, the oil yield and the analytical characteristics of the oils. Moreover the effects of nitrogen fertilization on the seed production and on oil characteristics were tested. The achieved results have pointed out that, referring to the chosen environment, the cv. "Matador" and "Leonessa" show the highest seed and oil productions, whereas oils extracted from the cv. "Sinus", "Erusine" and "Sinera" contain the minor quantities of erucic acid. It seem that nitrogen fertilization exerts no appreciable influence on rapeseed oil composition. The possibility of the utilization of cv. with law content in erucic acid confirms the practical validity of the cultivation of rapeseed as on oil plant.