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At least 19 recordsLinked to original sources
PubMed1978

Changes of adrenal catecholamines and their synthesizing enzymes during ontogenesis and aging in rats.

Male Wistar specific-pathogen-free rats aged 2, 7, 17, 30, 60, 120, 200, 360 and 600 days, all killed in experiment on the same day, were examined. The body weight significantly increased until the 200th day, the weight of adrenals until the 120th day and the adrenal protein content until the 30th day of life. The adrenaline content of the adrenals increased continuously during the 600 days studied. Adrenal noradrenaline content increased rapidly over the first 17 days, remained at a stable level until the 120th day, and rose to a higher level after 200 days. The activity of adrenal catecholamine-synthesizing enzymes also increased with age: tyrosine hydroxylase gradually increased until the 360th day, dopamine-beta-hydroxylase and phenylethanolamine-N-methyl transferase until the 200th day. Our results demonstrate that, in the rat, during development there is a gradual increase of adrenal weight, adrenaline content, tyrosine hydroxylase and phenylethanolamine-N-methyl transferase activity until maturation (120th day), whereas the adrenal noradrenaline content reaches the adult values earlier, around the 17th day. During aging, adrenal catecholamines significantly increase when compared to young-adult rats (120-day-old), probably due to the elevated activity of the adrenal catecholamine-synthesizing enzymes. The increased adrenal catecholamine levels in old animals might be connected with a higher incidence of cardiovascular diseases in aged.

Adrenal Glands↗
PubMed1975

Short-term oral and dermal toxicity of MCPA and MCPP.

The herbicieds 2-methyl-4-chlorophenoxy acetic acid (MCPA) and 2-(2-methyl-4-chlorophenoxy) propionic acid (MCPP or mecoprop) were tested for 90 days in rats. The compounds were added to the diet at levels of 0, 50, 400, and 3200 ppm. Growth, food intake, mortality, haematology, blood and liver chemistry, organ weights and histopathology were used as criteria. The main effects of both compounds were growth retardation and elevated relative kidney weights at levels of 400 ppm and more. The 50 ppm dose level can be considered as a no-toxic-effect level in the 90-day study. In subacute dermal studies in rabbits during 3 weeks the dosages were 0, 0.5, 1.0 and 2 g MCPA or MCPP per kg body weight. Therafter followed a recovery period of 2 weeks. Growth, mortality, skin reaction, haematology, organ weights (MCPP) and histopathology were recorded and determined. Both compounds caused slight to moderate erythema at all dose levels, whereas elasticity of the skin was decreased. In both experiments the skin returned to normal during the recovery period. Weight loss was observed at all dose levels. In the MCPA experiment high mortality and histopathological changes in the liver, kidneys, spleen and thymus were recorded at the two highest dose levels. The cause of this could have been either the treatment with MCPA or a dysbacteria infection which developed during the experiment. Oral and intraperitoneal acute toxicity of MCPP for the rat were found to be 1210 and 402 mg/kg, respectively. After a single oral or dermal application of MCPA to the rabbit, the compound was excreted unchanged in the urine.

Administration, Oral↗
PubMed1975

Effects of corticosteroid treatment and inflammation on the cellular content of blood and exudate in mice.

Inflammatory exudates have been produced in mice by intraperitoneal injection of thioglycollate broth 24 hr and again 3 hr before collecting of the exudate. The first injection of broth exerts a "priming" effect leading to an enhanced response to the second injection. By this procedure more than 30 x 106 leucocytes of which 78 per cent. were polymorphs were obtained from each mouse. Administration of paramethasone reduced the number of cells in the exudate when given at the same time as broth but not when given 3 hr before collection of the exudate. In contrast paramethasone was equally effective when given either 24 hr or 3 hr before harvest in suppressing the appearance of intravenously injected pontamine sky blue in the exudate. It was striking that treatment with paramethasone which had reduced the number of polymorphs in the exudate had actually increased the number in blood.

Animals↗
PubMed1975

Comparison of the local effects of amiloride hydrochloride on the isotonic fluid absorption in the distal and proximal convoluted tubule.

The isotonic fluid absorption (Jv) was measured under standard conditions in the proximal and distal convolution of the rat kidney. The peritubular blood capillaries were perfused simultaneously. Amiloride was applied either intraluminally or peritubularly. When applied intraluminally, amiloride strongly inhibited Jv in the distal tubule at concentrations up to 10(-6) M. In the proximal tubule similar effects were obtained only after intraluminal application of one thousand-fold greater concentrations of amiloride. In contrast to amphibian epithelia, amiloride also inhibits Jv in the distal tubule when applied peritubularly, but at higher concentrations and less completely than after intraluminal application. Amiloride was found to be generally more effective in the distal tubule than furosemide and mefruside, although in the proximal tubule it was less effective than these diuretics. That amiloride is most effective after intraluminal application in the distal tubule would suggest a dominant action at the luminal membrane of the distal tubule cell, while not excluding a concomitant effect at the peritubular membrane.

Absorption↗
PubMed1975

Light and electron microscopic observations on the carotid bodies of rats following adaptation to high altitude.

The carotid bodies of rats were investigated by light and electron microscopy following adaptation to a simulated altitude of 7000 m. Some animals were studied immediately after readaptation to sea-level, other groups up to 41 days later. The animals of the first group show enlarged glomera with dilated capillaries as reported earlier. The type-I-cells are large with a light staining cytoplasm. The lobular configuration of the glomus is lost and intracapillary platelet thrombosis are frequently found. Under these thrombi there is usually a chief cell degeneration with edema and vacuolisation. There is also a noticeable decrease in so-called catecholamine bodies and the remaining ones are usually arranged along the cell borders. Electron microscopically the intercapillary tissue reveals an increase in collagen material partially replanning lost chief cells. Essentially unaltered sustentacular cells frequently enclose with their processes only collagen bundles and nerve fibres. During 41 days following the readaptation there is a narrowing of capillaries and vacuolisation, swelling and thromboses are no longer observed. The amount of collagen, however, remains the same. Dense cored vesicles again increase in number and the chief cells show a prominent interdigitation. Light microscopically the restoration to normal appears to be almost complete. Fine structural analysis, however, shows an appearently permanent distortion in the composition and cellular arrangement of the glomus.

Adaptation, Biological↗
PubMed1975

The interaction between Walker tumour cells and mucosa cells in the lamina propria of gastric mucosa in rats. The tumour behaviour in previously X-irradiated mucosa compared to normal mucosa.

One series of 12 rats was exposed to X-irradiation (1500 R) of the stomach 19 days before implantation of Walker tumour cells in the gastric mucosa, and the frequency of tumour take and the extent of tumour growth after 10 days were compared with a second series with the same tumour implantation, but without X-ray exposure. In a third series simple gastric ulcers without tumour were produced by clamping the gastric wall with a heated (80 degrees) surgical needle holder, and the animals were killed 5-7 day later. All the rats were given injections of vinblastine sulfate 3 hours and of 3H-TDR 1 hour before sacrifice. In viewfields with diameter 180 mu the vinblastine-arrested mitoses and labelled cells on the tumour side of the tumour/mucosa border were calculated as percentages of all tumour cells. In the mucosa the total number of proliferating cells was counted at various distances from the border of the tumour or ulcer. No clear differences in the frequency of tumour take and the extent of tumour growth were found between the X-irradiated and the normal rat stomachs, and it is concluded that the X-ray exposure 3 weeks prior to tumour implantation did not reduce the normal mucosal resistance to tumour growth. The percentage of arrested mitoses and labelled cells in the tumour decreased one view field away from the mucosal border, and the number of proliferating cells in the mucosa bordering on the tumours showed a gradual fall with increasing distance up to 0.8-1.0 mm from the tumour border; within these distances, however, the numbers were much higher than at corresponding distances from edges of the ulcers. The Walker tumour thus seems to stimulate cell proliferation in mucosa to a much greater extent than a simple ulcer does. The causes of this phenomenon and the possible roles of "chalones" or "anti-chalones" are discussed.

Animals↗
PubMed1979

Flow of reducing equivalents into isolated intestinal mitochondria.

A system of enzymes is required for the transport of reducing equivalents from reduced nicotinamide adenine dinucleotide (NADH) generated in the cytosol into the mitochondria by the substrate cycles. Also, the intestinal mitochondria must be capable of oxidizing the substrates of the cycles. Both substrate cycle enzymes and permeable mitochondria are necessary for the flow of pyruvate derived from glucose into the mitochondria for oxidative decarboxylation and for the efficient production of adenosine 5'-triphosphate (ATP) for the unique intestinal nutrient transport functions. Mitochondria from hamster intestinal mucosa were prepared exhibiting good respiratory control ratios. The isolated intestinal mitochondria would not oxidize NADH unless N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) was added as a carrier of reducing equivalents. The rates of oxidation of the substrates of the L-glycerol 3-phosphate and the L-malate/1-aspartate substrate cycles were measured with the mitochondria isolated from the small intestinal mucosa. The key enzymes measured in the cytosol and mitochondria from the mucosa were NAD-L-glycerol 3-phosphate dehydrogenase, Fp-L-glycerol 3-phosphate dehydrogenase, L-malate dehydrogenase and L-glutamate-oxaloacetate transaminase. In addition, the substrate cyclase were simulated in vitro by following NADH oxidation by isolated mitochondria in the presence of added cytosolic constituents.

Animals↗
PubMed1975

Eimeria falciformis (Eimer, 1870) in specific pathogen free and gnotobiotic mice.

The endogenous and exogenous stages of a species of murine Eimeria were examined and compared with descriptions of other species isolated from Mus musculus. Developing stages of the parasite were found in the epithelial cells of the caecum and colon. Three asexual generations were observed, the third becoming apparent on the fourth day concurrently with gametogeny. The total length of the prepatent period was 5 days. Oocysts of the coccidian, identified as Eimeria falciformis, were administered to a group of germfree mice. Despite a dose level of 1 x 10(6), the coccidium was not established. Histological examination indicated the failure of the sporozoite to penetrate its host epithelium. The possible causes of this phenomenon were discussed.

Animals↗
PubMed2001

Bunyamwera bunyavirus nonstructural protein NSs is a nonessential gene product that contributes to viral pathogenesis.

Bunyamwera virus (family Bunyaviridae, genus Bunyavirus) contains a tripartite negative-sense RNA genome. The smallest RNA segment, S, encodes the nucleocapsid protein N and a nonstructural protein, NSs, in overlapping reading frames. We have generated a mutant virus lacking NSs, called BUNdelNSs, by reverse genetics. Compared with the wild-type (wt) virus, BUNdelNSs exhibited a smaller plaque size and generated titers of virus approximately 1 log lower. In mammalian cells, the mutant expressed greatly increased levels of N protein; significantly, the marked inhibition of host cell protein synthesis shown by wt virus was considerably impaired by BUNdelNSs. When inoculated by the intracerebral route BUNdelNSs killed BALB/c mice with a slower time course than wt and exhibited a reduced cell-to-cell spread, and titers of virus in the brain were lower. In addition, the abrogation of NSs expression changed Bunyamwera virus from a noninducer to an inducer of an interferon-beta promoter. These results suggest that, although not essential for growth in tissue culture or in mice, the bunyavirus NSs protein has several functions in the virus life cycle and contributes to viral pathogenesis.

Aedes↗
PubMed1978

Mechanisms of clonal abortion tolerogenesis. I. Response of immature hapten-specific B lymphocytes.

B lymphocytes with receptors specific for the hapten fluorescein (FLU) were prepared from the spleens of mice of various ages. For most experiments, a one-step fractionation procedure based on the adherence of FLU-specific cells to FLU-gelatin was used. For some experiments, a subset of higher FLU-binding capacity was prepared from the FLU-gelatin binding population through the use of the fluorescence-activated cell sorter (FACS). FLU-specific B cells were placed into microculture with either FLU(3.6)-human gamma globulin (FLU(3.6)HGG) or FLU(12)HGG usually for 24 h at 37 degrees C. The tolerogen was then removed and 0.1 mug/ml of a T-independent antigen, FLU-polymerized flagellin, was substituted. 3 days later, cells were harvested from the microcultures and assayed for FLU-specific plaque-forming cells to determine any reduction in clonable hapten-specific B cells which the tolerogenesis treatment might have induced. The results showed that with FLU(3.6)HGG, hapten-specific newborn B cells could be tolerized at 1,000-fold lower tolerogen concentrations than adult splenic B cells of equal antigen-binding capacity. The high-avidity subset was even more susceptible to tolerance induction. Tolerance could be induced within 8 but not within 2 h, and at lower tolerogen concentrations, longer periods of tolerogenesis were required for a given effect. Using a 24-h tolerogenesis phase, 50 percent reduction in clone frequency among newborn FLU-gelatin fractionated cells was achieved at 0.08 mug/ml of FLU(3.6)HGG. Tolerance induction in immature B cells was inhibited by the concomitant presence of a polyclonal B-cell activator, Escherichia coli lipopolysaccharide (LPS) but tolerance once induced, was stable to challenge with LPS. Tolerogenesis was hapten specific. The proportion of tolerizable cells in spleens decreased with increasing age, reaching 50 percent at around 9 days. FLUI(12)HGG proved a more powerful tolerogen than FLU(3.6)HGG. It had an effect on adult cells, 50 percent reduction in clone frequency being noted at around 1 mug/ml. However, and in contrast to results claimed for other T- independent systems, there still was a major difference between immature and mature B cells, the immature cells displaying much greater sensitivity to tolerogenesis.

Animals↗
PubMed1977

Pathological changes during aging in barrier-reared Fischer 344 male rats.

Pathology, microbiology, and selected serum chemistries were evaluated in 144 male Fischer rats from 4 to 33 mo of age. The rats were reared and maintained under barrier conditions, which successfully excluded the introduction of major infectious disease agents throughout the entire study, including Mycoplasma pulmonis. A wide variety of pathology was found and tabulated, and many lesions were found to increase in severity and incidence with age. There was a high correlation of renal disease severity with increasing age, while alpha-1 globulin and cholesterol increased.

Adenoma, Chromophobe↗
PubMed1976

Dietary fatty acids on the control of glucose-6-phosphate dehydrogenase and malic enzyme in the starved-refed rat.

The role of dietary unsaturated fat in the control of hepatic glucose-6-phosphate dehydrogenase (G6PD) (EC 1.1.1.49) and malic enzyme (ME) (EC 1.1.1.40) was studied in rats subjected to one or two cycles of starvation-refeeding. Rats starved and refed a control (5% corn oil) diet showed a threefold increase in G6PD activity and a twofold increase in ME activity compared to ad libitum-fed rats. After a second cycle of starvation-refeeding G6PD and ME activities showed fourfold and threefold increases, respectively, as compared to ad libitum-fed rats. Feeding rats diets containing 8% linoleic acid (as triglycerides) prevented the increase in G6PD and ME activities upon starvation-refeeding, diets with oleic, palmitic, and stearic acis when fed did not prevent this increase. Feeding rats various combinations of linoleic, linolenic and oleic acids following starvation prevented the additional increase in G6PD and ME activities after a second starvation-refeeding cycle; however, linoleic acid fed alone during the first refeeding prevented the additional increase in ME activity but not in G6PD activity. It is suggested that the dietary control of these enzymes involves one or more specific polyunsaturated fatty acids.

Animals↗
PubMed1975

Effect of tilorone treatment on intracellular microbial infections in specific-pathogen-free mice.

Specific-pathogen-free CD-1 mice were treated orally with the drug tilorone (2,7-bis[2-diethylaminoethoxy]fluoren-9-one hydrochloride) at dosages of 10 or 100 mg per kg of body weight. Drug was given 24 h before challenge and then every other day for up to 15 days. Growth of sublethal doses of Listeria monocytogenes, Mycobacterium bovis (BCG Montreal), M. tuberculosis H37Rv, and Salmonella enteritidis in the livers and spleens of intravenously challenged mice was significantly increased compared with that in control animals receiving distilled water orally. Tilorone given every other day at a dosage of 10 mg/kg reduced (but did not completely ablate) the tuberculin response to the mycobacterial infections. Both tuberculin hypersensitivity and anti-mycobacterial resistance returned to normal values within days of stopping the drug treatment. Tilorone treatment at the 100-mg/kg dose level increased the growth of S. enteritidis in both intravenously and intragastrically challenged mice; this effect seemed to be due to the reduced ability of the host to express the normal granulomatous response to the microbial infection within the liver and spleen.

Animals↗
PubMed1975

Effect of oral niridazole treatment on some bacterial infections in mice.

Treatment of specific-pathogen-free CD-1 mice with oral doses of 10 or 100 mg of niridazole per kg of body weight given 24 h before challenge and then every other day for up to 15 days altered the growth curves for Listeria monocytogenes, Mycobacterium bovis (BCG Montreal), M. tuberculosis H37Rv, and Salmonella enteritidis seen in the livers and spleens of the treated animals. Niridazole in an oral dosage of 10 mg/kg reduced (but did not eliminate) tuberculin hypersensitivity in the mycobacteria-infected mice. Both delayed hypersensitivity and antimycobacterial resistance quickly returned to normal levels once the drug treatment was stopped. Niridazole treatment reduced the growth of S. enteritidis in both intravenously and intragastrically challenged mice; this seemed to be due to the antibacterial action of the drug on the salmonellae both in vitro and in vivo.

Animals↗