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Biomedical subjects

N Hartmann

Publications and source records attributed to N Hartmann.

At least 37 records · Page 2Linked to original sources
PubMed1981

[Effect of high-fat diet on the contents of total cholesterol, free cholesterol and esterified cholesterol in the serum and liver of rats].

Four-week-old male Wister Rats were fed a diet containing 50% of fat up to the age of 9 weeks and 6 months, respectively. The control group received a diet with 3% of fat. The fat consisted of lard (1/3) and sunflower oil (2/3). Serum cholesterol was determined according to the standard method 1 of the DAB 7 (German Pharmacopoeia); liver cholesterol was estimated by the method of Naito and Lewis. As compared to the control animals, the 9-week-old rats on the high-fat diet showed serum cholesterol values (total, free and esterified cholesterol) which were significantly lower. There was no difference in serum cholesterol level between the 6-month-old rats on the high-fat diet and the control animals. In contrast to this, the liver cholesterol levels of the 9-week-old and the 6-month-old rats on the high-fat diet were significantly increased. In both age-groups the ratio of free cholesterol to esterified cholesterol was changed in favour of the esterified cholesterol. The present results confirm the findings reported in the literature, except for the unchanged serum cholesterol values observed by the authors in the long-time dietary experiment.

Animals↗
PubMed1981

[Effectors and products of enzymatic diiodotyrosine deiodination by a plasmatic fraction from pig liver].

Effectors and products of enzymatic diiodotyrosine (DIT) deiodination by a cytosolic fraction of pig liver hab been investigated. 13% of the degraded 131I-DIT was found as monoiodotyrosine by thin layer chromatography. The main quantity of the deiodinated DIT was found on the start point of the chromatogram bound to enzyme protein. Tyrosine as a reaction product of enzymatic deiodination of [14C]-IT could not be identified exactly. The liver cytosolic deiodinase is activated by pyruvate; the extent of activation depends on th pyruvate concentration. Diiodohydroxyphenylpyruvate as a product of transamination and theoretically possible intermediate product could be excluded. NADPH 2 and sodium dithionite activated the deiodinase to 1/3, sodium dithionite together with FAD to 1/2 the amount of which was determined for the action of pyruvate. The enzymatic activity in the presence of pyruvate and NADPH2, respectively NADPH2/FAD is identical with the sum of the single activities. The effect of dithionite and sulfite on deiodinase activity depends on the concentration: low effector concentrations increase, while high concentrations decrease the enzyme activity. The liver plasma deiodinase was inactivate quantitatively by reaction with 10(-4) M PCMB; by reaction with 10(-4) M DTNB or NEM the inactivation was 40% only. The inactivation of deiodinase by PCMB was quantitative reversible by cysteine, while inactivation by DTNB was reversible by cysteine to maximal 70% only. Differences between cytosolic and microsomal deiodinases are discussed also in regard to the mechanism of DIT-deiodination by a liver cytosolic fraction with direct participation of SH-groups.

Animals↗
PubMed1980

[Cholesterol esterification in the serum of hypothyroid rats].

The ratio of unesterified to total serum cholesterol in hypothyreotic rats has been studied. Extreme rat hypothyreosis of identical degree was induced by radiothyroidectomy (group R-HT) and feeding of thyreostatics (groups MTU-HT and MMI-HT). Determination of total serum cholesterol content and the unesterified cholesterol content resulted in following changes (all changes significant for p < 0,001): 1. Higher total cholesterol in hypothyreotic rats 4 and 7 weeks after beginning the experiments as compared to the controls. 2. The ratio of unesterified cholesterol to total cholesterol was increased in all hypothyreotic groups. It is discussed, that the esterification reaction in serum catalyzed by the lecithin-cholesterol-acyltransferase (LCAT) is diminished in the hypothyreotic state.

Animals↗
PubMed1980

[The lactate-pyruvate quotient in the framework of modern thyroid diagnosis].

In literature a big number of central and peripheral parameters for the diagnosis and control of therapeutical measures in diseases of human thyroid gland is described. That means, that none of the methods used has a sufficient weight. The enzymatic estimation of pyruvate and lactate reflect the peripheral effect of the hormones of thyroid gland. The pyruvate and lactate levels differ in the several groups of patients with euthyreosis, hypothyreosis, hyperthyreosis and euthyreotic goitre. Between these all groups the lactate/pyruvate ratio showed highly significant differences. The comparison of the lactate/pyruvate ratio and the T3-values showed highly significant correlation between both parameters. This good conformity is underlined by the behaviour of the parameters in courses of therapy, with additional support by farther functional tests--ETR-, T3- and T4-test. Our results confirmed the suggestion, also in agreement with literature, that the lactate/pyruvate ratio represent a possible enrichment in the laboratory programme for diagnosis and control of therapy in patients with thyroid diseases.

Adolescent↗
PubMed1980

[Liver deiodase activity in rats of different body weight and fat contents following high or low fat diet. Comparison of enzymatic deiodination with T4-clearance rate and thyroid activity in animals].

Weanling male wistar rats were fed 4 weeks a standard diet and separated into 2 groups, which received a high fat diet (50% w fat; HFD) or a low fat diet (3% w fat; LFD). These diets were fed 6-8 weeks and the animals then separated into light and heavy animals in each group. T4 deiodination in liver homogenates was investigated in all groups and compared with T4 clearance rate and thyroidal activity of these animals. The HFD-rats showed independently of weight and body fat content significantly higher liver deiodinase activity than LFD-rats. In light and heavy HFD-rats with great differences in body fat content the liver deiodinase activity was equal. T4 deiodination in liver, contrary to the T4 clearance rate, depends on fat content of diet and not of body. The thyroidal radioiodine uptake and PBI-131-values in some weight groups of HFD-rats were significantly higher than in some LFD-weight-groups, but a dependence of the thyroidal activity from fat content of diet or of body was not clearly evident. The results indicate however, that the thyroidal activity is likely not responsible for the increase of liver deiodinase activity after high fat diet. The apparent discrepancy between the results of higher liver T4 deiodination and equal or lower T4 clearance rate or equal T3 serum concentrations is discussed.

Animals↗
PubMed1980

Barbiturate treatment and membrane stability of subcellular organelles.

The experimentally well established protective effect of barbiturate anaesthesia in cerebral ischaemia and increased intracranial pressure (ICP) has been assumed to be primarily a consequence of the reduction in cerebral metabolic rate. We present the results of studies of the influence of pentobarbitone on the stability of lysosomal membranes in the grey and white matter of the cat brain. To indicate the grade of stability of share of free activity of the lysosomal enzyme beta-glucuronidase was assayed. Animals pretreated by pentobarbitone showed a significant decrease of the share of free activity in the white matter. This indicates an increase in lysosomal membrane stability. Increased lysosomal membrane stability is regarded as a protective effect of pentobarbitone against brain ischaemia and severe head injury.

Animals↗
PubMed1979

[Effect of diet and L-thyroxine on deiodination of L-thyroxine in rat liver].

Male Wistar rats on 3 or 50% fat diet for 14 weeks were treated during 6 weeks with L-thyroxine (5 or 25 or 50 microgram 100 g body weight/2 times weekly, sc.) and the activity of L-thyroxine-deiodinase was determined in supernatans of liver homogenates. With increasing thyroxine lading the deiodinating activity increases statistically significantly within each diet group. The liver of animals on 50% fat diet deiodinates increasing thyroxine doses to a lesser extent than livers of animals on 3% fat diet. It is discussed that high fat diet influences thyroid function and that thyroxine shares effectiveness and undergoes deiodination also in other tissues, probably in fat tissue, to a higher extent.

Animals↗
PubMed1979

[T4 metabolism in age matched heavy and light rats with good and bad feed efficiency following high- or low-in-fat diet].

Rats, fed two diets (high or low in fat content), were at the and of the feeding-period separated in light and in heavy animal groups. The leaner rats from the diet group high in fat content show opposite to the heavier animals of this diet group significantly increased T4 distribution spaces, significantly shortened T4 half life time and lower feed efficiency. T4 serum values, absolute T4 degradation per day and body mass and free thyroxine index in these leaner rats also increased significantly. However comparing heavy rats feed a diet low and light rats fed a diet high in rat content the latter show also a decreased feed efficiency, but no differences in T4 serum concentration or T3 binding capacity of serum proteins, free thyroxine index and T4 degradation. The results in T4 metabolism are discussed in relation to feed efficiency of the investigated animal groups.

Animals↗
PubMed1979

[Iodoamino acid distribution and weight of the thyroid gland, T4 serum level and T4 metabolism in relation to diet, body fat content and age of rats].

Rats were rendered obese by feeding them a fatty diet (HFD, fat: 50% of weight). At the end of the experimental period the animals were divided, also the control rats, which were fed a low-fat diet (LFD, fat: 3% of weight), in light and heavy weight groups. The heavy and obese HFD groups showed, unlike the light LFD-animals, equal absolute but significantly lower relative thyroidal weights. The absolute thyroidal weights of light and heavy animal groups, which received in each case the same diet, were identical, the relative thyroidal weights of the heavy rats on the other hand decreased significantly. The iodoamino acid distribution in the thyroid of rats showed no variation in animals fed various diets and differed in body mass and fat content. The T4 serum levels of the HFD-, in comparison to the LFD-animals increased significantly. Between light and heavy animals in equal diet groups no differences were obtained for the T4 serum values. The serum T3 levels of LFD- and HFD-rats were also equal. The heavy HFD- showed in comparison to the light LFD-animals a significantly lower T4 clearance and in the higher age groups a significantly extended T4 half-life time. The HFD- and LFD-rats with approximately equal body mass and body fat content showed no differences in T4 half-life time and T4 clearance rate depending on diet. A relation between higher body fat content and increased serum T4 levels as a possible adaption to obesity in heavy HFD-rats is discussed. By the comparison of younger and older rats in the most investigated diet and weight groups the older animals showed a decreasing tendency for K and TD/100 g KM and a significant decrease in the clearance rate and in the TD for T4, related to body mass. An influence of diet, body mass or fat content on the decrease of the T4 metabolism of rats with increased age is not evident. The T4 serum levels were not different in dependence on age, but the free T4 serum level was significantly lower in the older rats.

Adipose Tissue↗
PubMed1978

[Heart trauma caused by central venous catheter (author's transl)].

Four cases of extensive traumatic lesions of the right atrium induced by central venous catheter, are reported. In one case there was beginning in the other complete perforation of the right atrium. Such lesions can be caused by horizontal fixation of the intracardiac portion of a catheter due to wall-adherent thrombi; catheters held near the coronary sinus by a so-called Chiari net; or by coiling of the catheter within the atrium. Central venous catheters often cause endothelial lesions and thrombotic changes in the veins near the heart. Possible trauma to the right atrium, which could provoke fatal complications (e. g. haemopericardium or arrhythmias) must, therefore, be given special attention.

Adult↗
PubMed1978

[Properties of adipocytes (diameter, volume, triglyceride content, cell number) of certain types of fatty tissue as a function of age in male Wistar rats].

The diameter, volume, triglyceride content and number of adipocytes were determined in male Wistar rats at the age of 6 weeks and 2, 3, 12 and 18 months, respectively. A standard diet and water were given ad libitum. The adipocytes were isolated by means of the method of RODBELL. The weight and fat content of the fatty tissues were determined gravimetrically. Age exerts no effect on the adipocyte parameter, nor on the weight and the fat content of the fatty tissue. In contrast to this, there are relationships between adipocyte diameter and the increases in body weight. In all age groups, the increase in size and number of the adipocytes was significantly greater in heavy animals than in light ones. Genetic, hormonal and dietarily-induced factors are discussed as a possible cause. The authors observed no difference in adipocyte size between epididymal and perirenal fatty tissues. As compared to this, the mesenteric adipocytes were smaller.

Adipose Tissue↗
PubMed1978

[Effect of a high fat diet on the behavior of the diameter, volume, triglyceride content and number of the adipocytes in different types of fatty tissues in male Wistar rats].

The effect of a high-fat diet on the diameter, volume, triglyceride content and number of the adipocytes was studied in male Wistar rats at the age of 9 weeks and 6 months, respectively. The adipocytes were isolated by means of the method of RODBELL. The adipocyte diameters were measured using the microscopic method. The weight and the fat content of the fatty tissue were determined gravimetrically. A diet containing 50% fat increases the diameter, volume and triglyceride content of the adipocytes and also the weight and the fat content of the different types of fatty tissue. The fat content of the diet and the duration of feeding are of importance. The high-fat diet exerts no effect on the adipocyte number. However, in both age groups, the adipocyte numbers were sometimes greater in heavy animals than in light ones fed the same diet. Genetic, hormonal, and dietarily-induced factors are considered as a possible cause.

Adipose Tissue↗
PubMed1978

[Dietary proteins and deiodination in the liver].

The authors studied in male Wistar rats the effects of diets containing 66 and 2% (w/w) of protein on the one hand, and 18% (w/w) of protein on the other hand, on the deiodination of L-thyroxine in liver homogenate supernatants. The deiodase activity in the liver protein increased in case of low-protein diet, and decreased in case of high-protein diet; these differences were statistically significant. When the body weights of the animals were taken into account, the deiodinating power of the whole liver was significantly reduced in case of low-protein diet, but not significantly reduced in case of high-protein diet. Consequently, the reference value adopted for the calculation of the degree of deiodination is of paramount importance to validity.

Animals↗
PubMed1978

[Effect of diet and thyroxine on body composition in rats].

In young male Wistar rats the influence of different fat content of the diet (7 or 25 or 50 weight percent of fat) and of thyroxine (5 or 50 microgram/100 g body mass, 2 times/week, sc.) on body composition was investigated by carcass analysis. After high doses of thyroxine the percentage body fat decreases and protein and water content increases within the same diet group (7 or 25 or 50% fat diet). Smaller doses of thyroxine have only the same effect as high thyroxine doses in the 7% fat diet group; the body composition is unchanged in the 25% fat diet group, and in rats after 50% fat diet thyroxine even brings about an increase in body fat. It is concluded that the fat content of the diet makes thyroxine partly ineffective. A comparison of the different diet groups, also with or without thyroxine treatment, brings the result of significantly increased percentage body fat after 25 and 50% fat diet; body protein and body water decreases respectively. It appears from the present study that controversial results in literature concerning body composition after thyroxine treatment, may be caused by different diets, especially the fat content of the diets.

Animals↗
PubMed1978

[Uptake of utilizable food energy by light-weight and heavy-weight rats fed a low-fat or high-fat diet].

The uptake of utilizable dietary energy (DE) as affected by diet (containing 3 or 50% (w/w)fat), body mass (BM) and age was investigated in male Wistar rats. In comparing heavy-weight animals fed the high-fat diet (HFD) with light-weight animals fed the low-fat diet (LFD) (differences in BM up to 60%), it was found that the uptakes of DE calculated on animal were significantly higher (up to 55%) in the HFD animals than in the LFD animals; but there were no significant differences when the uptakes of DE were calculated on 100 g BM. Thus, the LFD rats (the diet of which contained a high proportion of protein (70% (w/w)) exhibited no reduced uptakes of utilizable DE as compared to HFD rats. Of the heavy-weight LFD animals and the light-weight HFD animals which showed virtually no differences in BM, the HFD animals take up more utilizable DE (per animal or per 100 g BM) than the LFD animals. This difference, which amounts to 60%, is statistically significant. The comparison of the uptakes of DE/animal/100 g BM by light-weight rats with those by heavy-weight rats fed the same diet showed that the uptakes by the heavy-weight animals were in most cases significantly greater. Consequently, the greater BM of the heavy-weight animals of the respective diet groups must be attributed to more efficient utilization of feed. This is also indicated by the fact that the light-weight HFD animals excret more fat in the faeces than the heavy-weight animals. The amount of fat excreted by the HFD animals is some 10-fold greater than that excreted by the LFD animals. However, when the amount of excreted fat is expressed in % of ingested dietary fat, the fat excretion is of the same order of magnitude on both diets.

Aging↗