Search PubMed⌕ Search

Biomedical subjects

A Weber

Publications and source records attributed to A Weber.

At least 559 records · Page 31Linked to original sources
PubMed1980

Age-related changes of liver tyrosine aminotransferase in senescent rats.

Tyrosine aminotransferase was induced in adult and senescent rat liver and its properties studied. We show the appearance of a 'cross-reacting material' for induced tyrosine aminotransferase of old rats compared to basal enzyme; this cross-reacting material can be provoked in adult rats after injection of cycloheximide, and suppressed in adult and old rats after injection of a serine protease inhibitor (tosylphenylalanine chloromethylketone). Other properties of induced tyrosine aminotransferase (thermostability, Km for tyrosine, isoelectrofocusing) are identical except for the proportion of the three forms and their sensitivity to trypsin in the absence of pyridoxal phosphate, which is increased in senescent animals. The suppression of cross-reacting material clearly indicates that it is not due to errors on old rat liver DNA but rather to post-translational modifications. This demonstrates also the role of serine proteases in tyrosine aminotransferase degradation. We suggest that induced enzyme of senescent rats would undergo a conformational change, possibly due to a release of pyridoxal phosphate from the enzymic molecules, which would thus become more susceptible to proteolytic attack than those of adult rats.

Aging↗
PubMed1980

[Problems of treatment with thyroid hormones. Thyroxin monotherapy or a T3/T4 combination preparation?].

At the instance of T3- and T4-measurements of the daily profile in the serum after the application of triiodothyronine and the usual T3/T4-combination preparations is referred to the unphysiologically high T3-peaks 2 to 4 hours after the application depending on the proportion of triiodothyronine. The three distributed all over the day doses of e.g. thyreotom do not sufficiently smooth such undulations. The lacking triiodothyronine serum peaks after application of pure thyroxin as a bolus confirm the demand of a thyroxin monotherapy. Nevertheless, for answering the question of the "physiologic thyroid hormone therapy" some problems remain open which are discussed. Taking into consideration these facts (particularly conversation and extrathyroid influence of the thyroid hormone metabolism) a combination of T3 to T4 in the ratio 1:10 is recommended.

Adult↗
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

Passive smoking at work.

Air pollution due to tobacco smoke and its effects on employees were investigated in 44 workrooms. For this purpose, the concentrations of CO, NO, NO2, nicotine, and particulate matter were determined, and 472 employees were interviewed about annoyance and irritations. The mean values of the concentrations of the components due to tobacco smoke are: CO = 1.1 ppm, NO = 32 ppb, NO2 = 24 ppb, nicotine = 0.9 micrograms/m3, particulate matter = 133 micrograms/m3. One third of the measured CO values exceeds a critical threshold of 2 ppm CO due to tobacco smoke. One quarter of the persons reports eye irritations at work. One third of the employees qualifies the air with regard to smoke at the workplace as bad. Forty percent of the interviewed persons are disturbed by smoke. The majority of the employees is in favor of a separation into smoking and non-smoking rooms. This seems to be the most appropriate preventive measure for the protection of nonsmokers at work.

Adult↗
PubMed1980

[Neck muscular tension due to repetitive work].

In our laboratory study 19 students effected 4 repetitive tasks of 70 min each. All four conditions had a motor task at the base and in addition two had to deal with discrimination. In the 2 tasks with discrimination, the electromyography of the neck muscles was distinctly higher than in the 2 other conditions. The tasks with discrimination were accompanied by a higher subjective tension, a lower heart rate variability and a slightly increased urinary excretion. The main cause for an augmentation in the muscle tonus might be the immobilisation of the neck.

Electromyography↗
PubMed1980

[Passive smoking in the work place].

The air pollution due to tobacco smoke and its effects on employees were investigated in 44 work-rooms. For that purpose the concentration of CO, NO, Nicotine and the Particulate Matter were determined and 472 employees were interviewed about annoyance and irritations. The mean values of the concentrations of the components due to tobacco smoke are: CO = 1.1 ppm, NO = 32 ppb, Nicotine = 0.9 micrograms/m3, Particulate Matter = 133 micrograms/m3. The use of an indicator is discussed. One third of the employees qualifies the air wit regard to smoke at work place as bad. 40% of the interviewed persons are disturbed by smoke. One quarter of th persons indicates eye irritations. The majority of the employees support a separation of the rooms in smoking and non-smoking areas. This seems to be the most appropriate preventive measure for the protection of the nonsmokers at work.

Adult↗
PubMed1980

Uptake of nucleotides and catecholamines by chromaffin granules from pig and horse adrenal medulla.

The uptake of nucleotides and catecholamines into chromaffin granules from adrenals of pigs and horses is similar to that previously seen in bovine chromaffin granules. The rate of [3H]ATP uptake at 2 mM-ATP concentration was 0.42 +/- 0.06 and 0.15 +/- 0.02 nmol/mg protein/min for pig and horse granules, respectively. The apparent Km's were 1.37 mM for pig granules, 0.89 mM for horse granules, and 1.2 mM for ox granules. The sensitivity of the uptake for nucleotides and catecholamine to specific inhibitors was found to be similar in granules from pig and ox, indicating that the same mechanisms of uptake are involved in both species.

Adenosine Triphosphate↗
PubMed1980

Tyrosine aminotransferase in senescent rat liver.

We have studied tyrosine aminotransferase in the liver of adult and old rats. Thermostability and trypsin action were not modified, and no charge differences have been found by isoelectric focusing between 'adult' and 'old' enzymes. Inducibility by glucocorticoids was increased in vivo in these 27- to 31-month-old rats, but not in vitro, in cultured hepatocytes. Moreover, we have shown the absence of 'cross-reacting material' for tyrosine aminotransferase in senescent rat livers. The rapid turnover of this enzyme may explain the apparent absence of alterations during aging.

Aging↗
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

Immunolocalization of fetal aldolase isoenzymes in rat regenerating liver after carbon tetrachloride intoxication.

Light and electron microscopic immunolocalization of adult and fetal aldolase isoenzymes has been studied in rat liver 72 h after CCL4 intoxication. As in rat regenerating liver after partial hepatectomy, fetal aldolases A and C were located in sinusoidal cells (Kupffer and endothelial cells) whereas adult aldolase B was present in hepatocytes only. Our results are different from those obtained with fetal and cancerous livers; they suggest that control mechanisms of gene regulation different in liver regeneration and in cancer.

Animals↗
PubMed1980

Enzootic bovine leukosis: prevalence of blood lymphocyte nuclear pockets in dairy bulls in the United States and foreign countries.

Studies of the incidence of enzootic bovine leukosis-related blood lymphlymphocyte nuclear pockets (LNP) were made of 743 dairy breed bulls in the United States and foreign countries. Statistical evaluation disclosed that the prevalence of these anomalous nuclear forms in the studs observed is significantly greater in the United States than in other countries. In particular, the average percentage of LNP-containing cells in each United States stud is estimated to be more than twice the level found in all but two non-United States studs studied and more than three times the level in the majority (10 of 19) of them. Moreover, United States studs exhibited a higher proportion of LNP-suspicious and -positive cases than almost all of the non-United States studs. We believe this is valid evidence that serves to reinforce the expressed need for a federal surveillance program for enzootic bovine leukosis in the United States.

Animals↗
PubMed1980

[Investigations on the determination of doxycycline concentrations in biological material by high pressure liquid chromatography and the agar diffusion method (author's transl)].

A new high performance liquid chromatographic method for quantitative analysis of doxycycline has been compared with the microbiological assay. Both analytical methods yielded the same results of nearly 100% recovery when doxycycline was incubated with serum, lung-, or liver-homogenate (Table 1). The advantages of the chromatographic method over the microbiological method are i. short and simple way of analysis (Fig. 1), ii. need of only small amounts of biological material. In a pilot study doxycycline - after i.v. application to mice - could be analyzed in good agreement by both methods (Fig. 2). The microbiological analysis yielded in slightly lower serum- or organ-levels what might be due to an inactivation of the antibiotic attached to proteins to some extend.

Animals↗
PubMed1980

Continuous elemental enteral alimentation in children with Crohn's disease and growth failure.

Four children aged (11.7-13.5 yr) with protracted growth retardation related to Crohn's disease, received a 6-wk period of continuous elemental enteral alimentation with no other form of treatment. Despite drug therapy the yearly height and weight gain velocities of these children (1.7 +/- 0.3 cm and -0.8 +/- 1.4 kg, respectively) had been abnormal during the previous 2 yr. All patients experienced a complete remission of symptoms, improved nutritional status, and significant height (1.8 +/- 0.3 cm) and weight (3.8 +/- 0.5 kg) gains during the 67 wk of treatment. After cessation of elemental enteral alimentation, 3 of the 4 patients continued to grow, and over a period of 4.5 mo from the beginning of this form of nutritional therapy, they gained an average of 5.0 +/- 1.6 kg and 3.5 +/- 0.3 cm. The disease became active thereafter, and the 3 children resumed their previously abnormal growth patterns during the ensuing year. The 4th patient had surgery 2 mo after elemental enteral alimentation and experienced a subsequent second spurt of growth and pubertal changes. This study suggests that a relatively short course of elemental enteral alimentation leads to a temporary resumption of growth in children with severe growth failure and Crohn's disease. The possibility that repeated courses of elemental enteral alimentation might be beneficial needs to be explored.

Adolescent↗