Cell kinetics in the small intestine of suckling rats. I. Influence of hypophysectomy

Thyroid activity, pituitary and serum thyrotrophic potency in response to the administration of clomid, sexovid, PGE1 and PGF2alpha, were studied in H. fossilis. Hightened thyroidal activity and CR (conversion ratio of PB 131I in blood serum in relation to total serum 131I uptake) were noticed a week after clomid (150 microgram/fish/day) and sexovid (150 microgram/fish/day) treatment. Clomid and sexovid also elevated the serum thyrotrophic potency although pituitary TSH level was unaffected. It is evident from the results that clomid and sexovid either act via hypothalamus or directly over pituitary to increase TSH secretion followed by increased thyroid activity. PGE1 and PGF2alpha (100 microgram/fish/day, each) administration increased thyroidal 131I uptake but failed to stimulate hormone output from thyroid gland. Increased TSH level in blood and decreased level of TSH in pituitary was observed in response to the above prostaglandins. It seems that PGE1 and PGF2alpha inhibit thyroid hormone secretion like anti-thyroid drugs triggering the release of TSH into blood.     

The effect of dexamethasone on the pharmacokinetics of triazolam

OBJECTIVE: To determine whether incubator home care is desirable and feasible. DESIGN: Inventory. SETTING: Four neonatal units representative of the type of care in general hospitals in the Netherlands. METHOD: The relevant data on all infants with a birth weight < or = 2000 g admitted in the last 3 months of 1996 to one of four hospitals were analysed. Conditions for incubator home care were determined (e.g. absence of need for special care, vital function monitoring or nasogastric tube feeding). RESULTS: Forty-nine infants were enrolled. Mean hospital stay was 28.7 days in an incubator plus 19.7 days in a cot. When infants were placed in a cot they usually still needed tube feeding and monitoring of vital functions and sometimes parenteral nutrition, medication or extra oxygen which made home discharge impossible. Therefore a pilot study of actual home care could not be carried out. CONCLUSION: Although early home discharge is very desirable for newborn infants, the number of infants eligible for incubator home care is so small that further attempts to organise it are not useful.     

The effect of alpha-tocopherol and pentoxyfilline on ischemia-reperfusion induced liver injury in rats

BACKGROUND/AIM: In the present study our purpose was to investigate the effect of pentoxyfilline, that plays a role in microcirculation and tissue oxygenation, alone and in combination with an antioxidant vitamin E on tissue damage in the rat liver induced by ischemia-reperfusion. METHODOLOGY: Thirty-one albino rats were divided into four groups. Rats in group I (n= 7), group II (n= 8) and group III (n= 8) were given, respectively, pentoxyfilline (25 mg/kg), pentoxyfilline and vitamin E in combination (25 mg/kg and 50 mg/kg, respectively) and equal volume of saline solution intraperitoneally for 7 days. Rats in group IV (n= 8) served as controls and received no treatment. On day 7 ischemia was induced by cross-clamping the hepatic artery, portal vein and left branch of the biliary duct for 30 minutes. Malondialdehyde (MDA) and catalase activity were assessed in tissue sample, and the level of ALT was measured in serum obtained after reperfusion for 30 minutes. Histological examination of tissue sample was also carried out. RESULTS: There was no significant difference in ALT level between three study groups. Group I and group II had significant lower MDA and catalase levels than those of group III. The results of histopathologic examination in group I and group II were better than that of group III. CONCLUSION: Our findings suggested that the treatment of pentoxyfilline alone and in combination with vitamin E decreased liver damage induced by ischemia-reperfusion and that the effect of latter was more effective but the difference between the two treatment patterns was not statistically significant.     

Deprivation of dietary nucleotides decreases protein synthesis in the liver and small intestine in rats

BACKGROUND & AIMS: Dietary nucleotides are reported to influence the growth and functioning of the liver and small intestine. The aim of this study was to examine the mechanism by which nucleotides exert their effects in these tissues by assessing protein synthesis activity and related parameters in the presence or absence of dietary nucleotides. METHODS: Rats were fed a purified diet with or without nucleotides for 10 days. Fractional protein synthesis rate, RNA and DNA concentrations, polysome size distribution, and number of ribosomes were assessed. RESULTS: Fractional protein synthesis rates of the liver and small intestine were lower in the nucleotide-deprived group than in the control group. In the liver, RNA concentration was also lower in the nucleotide-deprived group, but values in the small intestine were similar in the two groups. In the liver, deprivation of nucleotides resulted in a reduction in the number of ribosomes and in polysome breakdown. Protein and DNA concentrations did not vary in the liver; however, the concentration of DNA was lower in the small intestine of the nucleotide-deprived group than in the control group. CONCLUSIONS: Dietary nucleotides can modulate protein synthesis in the liver and small intestine as a result of tissue-specific nucleic acid changes.     

The effect of sulphamethoxypyridazine on liver and plasma levels of vitamin A in rats

1 Long-acting sulphonamides are highly bound to plasma proteins; the present study deals with the effects of this binding property upon a vitamin A compound also transported by plasma proteins. 2 Sulphamethoxypyridazine was administered in rats either orally or by intraperitoneal injection. 3 A significant fall in plasma vitamin A level and an increase in hepatic vitamin A concentration were observed. 4 These results suggest an interference by sulphamethoxypyridazine with the transport of vitamin A, either through competition between the drug and vitamin A for binding sites of plasma proteins, or through altered secretion of the vitamin from the liver.     

The role of experience in suckling maintenance in albino rats.

In Exp I nipple-attachment behavior in Sprague-Dawley albino rats was disrupted by raising rat pups in isolation from their mother and siblings on the 3rd–5th day after birth. In Exp II nipple attachment was maintained, however, in isolation-reared pups that received, on Days 3 and 4 postnatally, either 6 or 12 opportunities to search for, locate, and attach to the nipples of an anesthetized mother. Suckling remained severely disrupted on Day 5 in pups whose experiences on Days 3 and 4 were restricted to either nipple search alone or nipple attachment without previous search. Findings focus attention on the role of experience in suckling maintenance and suggest that in rats the suckling system is not fully specified at birth. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of dexamethasone on the reactions of the blood system in inflammation

On the model of carrageenan-induced acute aseptic peritonitis in rats it is shown that under influence of dexamethasone granulomonocytopoiesis, efflux of leukocytes to blood and their accumulation in inflammatory focus are increased and earlier completion of leukocytic reaction is observed and that the antiinflammatory effect of dexamethasone is mainly realized by the way of increasing of defence-adaptative blood system's reactions.     

The effect of a lyophilized extract of the mucosa of the proximal small intestine on kidney water- and salt-excretory functions in rats

Experiments on Wistar rats injected intragastrically deionized water (1 % of the body weight) and intra-abdominally 0.1 mg/kg of the lyophilized water extract (LWE) from the thin intestine have shown that under these conditions diuresis and excretion of K+ with the urine increase and retention of Na+ excretion decreases. After intragastric injection of isotonic NaCl solution, the LWE has exerted only the K-excretion effect. An increase in the LWE doses from 1 to 10 mg/kg has weakened all these reactions. It has been found in experiments in vitro that the LWE has exerted an activatory dose-dependent effect on Na, K-ATPase from the kidney cortex cells.     

The development of ketogenesis at birth in the rat

In the suckling newborn rat, blood ketone bodies begin to increase slowly 4h after birth and then rise sharply between 12 and 16h, whereas the major increase in plasma non-esterified fatty acids and liver carnitine occurs during the first 2h of life, parallel with the onset of suckling. In the starved newborn rat, which shows no increase in liver carnitine unless it is fed with a carnitine solution, the developmental pattern of the ketogenic capacity (tested by feeding a triacylglycerol emulsion, which increases plasma non-esterified fatty acids by 3-fold) is the same as in the suckling animal. This suggests that the increases in plasma non-esterified fatty acids and liver carnitine seen 2h after birth in the suckling animal are not the predominant factors inducing the switch-on of ketogenesis. Injection of butyrate to starved newborn pups resulted in a pattern of blood ketone bodies which was similar to that found after administration of triacylglycerols, but, at all time points studied, the hyperketonaemia was more pronounced with butyrate. It is suggested that, even if the entry of long-chain fatty acids into the mitochondria is a rate-limiting step, it is not the only factor controlling ketogenesis after birth in the rat. As in the adult rat, there is a reciprocal correlation between the liver glycogen content and the concentration of ketone bodies in the blood.     

Diet and gene expression in the intestine

Gene expression is central to the pathogenesis of many disorders. An ability to alter the expression of genes would, if their relationship to disease processes were fully understood, constitute a new modality of treatment. This review examines the evidence that nutritional factors can regulate genes in the gastrointestinal epithelium and it discusses the physiological relevance of such alterations in gene expression. Dietary regulation of the genes expressed by the epithelium confers three fundamental advantages for mammals. It enables the epithelium to adapt to the luminal environment to digest and absorb food better; it provides the means whereby mother's milk can influence the development of the gastrointestinal tract; when the proteins expressed by the epithelium act on the immune system, it constitutes a signalling mechanism from the intestinal lumen to the body's defences. Each of these mechanisms is amenable to manipulation for therapeutic purposes.     

Effect of dopamine-depleting brain lesions on suckling and weaning in rats.

Rats given large dopamine (DA)-depleting brain lesions as adults exhibit severe impairments in ingestive behavior and sensorimotor function. In contrast to these well-known effects, the present 2 studies showed that virtually complete destruction of central dopaminergic neurons produced no such dysfunctions when it occurred in neonates (Sprague-Dawley). Ss continued to suckle and grow, albeit somewhat more slowly, and they could be weaned readily when they were 27 days old. Although most brain-damaged Ss did not survive weaning when they were 18 days old (controls exhibited no difficulty), this failure appeared to be the consequence of their reduced body weight and related inability to maintain body temperature in a relatively cool environment (22°C). Such premature weaning occurred more successfully when growth was stimulated by rearing brain-damaged pups in small litters or when ambient temperatures were raised to 31°C to minimize heat loss. Results demonstrate that the effects of near-total DA-depleting brain lesions are considerably less severe when they occur in infants than when they occur in adults, and, consequently, they reveal a capacity for neural plasticity during development that is no longer present at maturity. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modulation of chemosensitivity through altered expression of cell cycle regulatory genes in cancer

Alterations in the expression of genes affecting cell cycle progression occur in all human cancers. These may occur either by overexpression of genes such as cyclin D1, mutation of regulatory genes such as p16, or abrogation of checkpoints following DNA damage as in the cases of mutation or deletion of the p53 gene. Perturbation of the normal functions of these genes has a profound effect on cellular proliferation, differentiation and apoptosis. There is increasing evidence that such alterations may modulate the cellular response to treatment with chemotherapeutic agents. In many cases genetic alterations may induce resistance to drug treatment as in the case of mutations of the p53 gene. However, the deregulated expression of cell cycle genes may also increase sensitivity to treatment by directly altering the expression of the target for chemotherapeutic drugs as in the case of deletion of the retinoblastoma gene. It is crucial to understand the interactions between drug mechanisms of action and the genetic alterations in cancer to exploit potential areas in which the alterations found in tumors may constitute potential vulnerability.     

The effects of combined dexamethasone and indomethacin treatment on the outcome of pregnancy in the rabbit

Codeine was administered to rabbits and rats during the organogenetic phase (days 6--18 and 6--15, resp.) in oral doses of 5, 12.5 and 30 mg/kg and 10, 35 and 120 mg/kg, resp. The tests in rabbits yielded no indication of a teratogenic or embryolethal action of the substance under investigation. Even in the experiments on rats no teratogenicity could be realised. The highest dose of 120 mg/kg led to an increased mortality of rat embryos around the time of implantation. As this dose was toxic even to adult rats the described experiments give no indication of an increased risk during pregnancy.     

Localization of glycogen synthase activity in liver of fasted normal and adrenalectomized rats after injection of dexamethasone

Hepatic glycogen synthase activity was localized in normal and adrenalectomized (ADX) rats after fasting overnight and in fasted ADX rats after injection of dexamethasone (DEX) 2-8 h prior to sacrifice to stimulate glycogen synthesis. Cryostat sections were incubated in medium containing substrate to demonstrate glycogen synthase activity as indicated by glycogen synthesized during incubation. Sections from fasted normal rats showed limited dispersed glycogen synthase activity in both periportal and centrilobular regions. In contrast, activity for glycogen synthase in hepatocytes from fasted ADX rats appeared as large aggregates in random hepatocytes throughout the lobule. Two hours after injection of DEX the reaction product appeared as aggregates in some hepatocytes, but other cells revealed dispersed enzyme activity. Glycogen synthase activity was evident in more hepatocytes after 4 h treatment with DEX and after 8 h virtually all hepatocytes contained abundant reaction product. The results suggest that synthase activity becomes concentrated in limited regions of selected hepatocytes in fasted ADX rats. DEX stimulation of glycogen synthesis for 4-8 h results in increased enzyme activity.     

The protective effect of hyperbaric oxygenation on the small intestine in ischemia-reperfusion injury

Hyperbaric oxygenation has been used as the method of treatment in several ischemic diseases, but its effectiveness still remains controversial. The authors investigated the effect of hyperbaric oxygenation on ischemia-reperfusion injury of the small intestine using a rat model. Wistar King A Makino (WKAM) rats were subjected to 120 minutes of superior mesenteric artery occlusion before reperfusion, with 90 minutes of hyperbaric oxygenation (two absolute atmospheric pressure in an experimental hyperbaric chamber) during ischemia in group A and immediately after reperfusion in group B, and no hyperbaric oxygen was provided to group C. Jejunal samples 1.5 cm in length were taken at the end of ischemia in all groups, at 30 minutes after reperfusion in groups A and C, and at 120 minutes after reperfusion in groups B and C, for the measurement of adenine nucleotides (high-performance liquid chromatography method) and for histological examination (hematoxylineosin [HE] staining). The survival rate was significantly higher in group A than in group C. The amount of adenosine triphosphate in the samples was not significantly different among the three groups, whereas the energy charge at the end of ischemia was significantly higher in group A than in group C. Histologically, the damage to the mucosa and the longitudinal muscle layer decreased in group A compared with that observed in groups B and C. These results suggest that hyperbaric oxygenation during ischemia is able to ameliorate ischemia-reperfusion injury in the rat small intestine.