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Biomedical subjects

E Michalska

Publications and source records attributed to E Michalska.

At least 19 recordsLinked to original sources
PubMed1990

Role of acid proteases in brown adipose tissue atrophy caused by fasting in mice.

The lysosomal proteolytic capacity of mouse brown adipose tissue (BAT) and its role during fasting were evaluated. The specific activities of acid phosphatase and cathepsins B, D, H, and L were measured in BAT of mice acclimated at 33, 21, and 4 degrees C and in BAT undergoing different rates of protein loss during a 24- to 48-h fast. The specific activities of lysosomal proteases in BAT did not vary with the acclimation status of the animals. Mice acclimated at 33 degrees C showed no significant atrophy of BAT after a fast. In mice kept at 21 degrees C, protein loss from BAT was observed after a fast without change in tissue DNA content. Protein loss from BAT was partially reduced by injection of the acidotropic agent chloroquine. Furthermore, tyrosine release from BAT during fasting was also reduced by injections of chloroquine or leupeptin, a thiol-protease inhibitor. Tyrosine release from BAT was maximum within 24 h and returned to prefast values by 36 h, suggesting rapid activation followed by inhibition of the tissue proteolytic activity. However, there was no change in acid protease specific activities, suggesting that these enzymes were not limiting for protein degradation. When cold-acclimated mice were fasted at 21 degrees C, BAT protein loss was markedly enhanced and increases in cathepsin D and L activities were observed, but there was no change in cathepsin B and H and acid phosphatase specific activities. These results indicate that BAT contains an important lysosomal proteolytic pathway that is involved in the rapid reduction of the tissue thermogenic capacity during a fast.

Adipose Tissue, Brown↗
PubMed1987

Multiphasic growth curve analysis in mice.

Growth curves of mean body weights were compared to those of individual weights when fitted to data of male and female mice using monophasic (logistic) and triphasic growth functions. Goodness-of-fit was determined by residual variances and Durbin-Watson statistics. These criteria suggest that the triphasic function, with smaller and less correlated residuals, describes the data better than the monophasic function. For the triphasic function, residual variances were higher when fitting individual weights than mean weights. Males had higher residual variances than females. Auto-correlation was negligible when fitting individual weights for males and for females. Parameters of the triphasic function were higher when fitting curves of individual weights than curves of mean weights; differences between curves within sex were small. Parameters were similar for males and females, especially in the first phase of growth. Half asymptotic weights for the second and third phases were higher for males than for females. From these results, it should be clear that using a multiphasic function to describe growth curves in mice provides greater insight for understanding the biology of growth.

Aging↗
PubMed1985

Conjugated catecholamines in rats transfused with perfluorocarbon blood substitute.

The reappearance of circulating catecholamines (CAs) after transfusion with perfluorocarbon blood substitute and the importance of blood for CA conjugation were determined in rats. Arterial plasma concentrations of unconjugated (i.e. free), sulfoconjugated and glucuronoconjugated forms of the CAs dopamine (DA), noradrenaline (NA) and adrenaline (AD) in cannulated, anesthetized, control rats remained stable during the 4.5 h long experiments. Contrarily, in parallel experiments with another group of rats, replacement of blood by the perfluorocarbon blood substitute initially lowered the arterial concentrations of DA glucuronide, free AD and AD glucuronide; subsequently, free DA, NA and AD increased, followed by delayed increases in conjugated CA levels. These changes in CA concentrations preceded a fall in systemic arterial blood pressure (pa) and thus were not the consequences of hypotension.

Animals↗
PubMed1979

Effect of immunosuppressive agents on the course of experimental syphilis in rabbits.

Rabbits infected intradermally with T. pallidum at four sites on the clipped back were treated with cyclophosphamide, 1 mg/kg body weight, twice before and every two days after inoculation for five months, or 5-fluorouracil 2.5 mg/kg body weight, according to the same regimen. Humoral response, as measured repeatedly by VDRL, FTA, and hemagglutination tests, was not affected by the application of the immunosuppressors. In contrast, the cell-mediated response, as determined by the Macrophage Migration Inhibition test was completely abolished in the treated rabbits. In the group of rabbits which were given immunosuppressors, syphilitic lesions appeared not only at the challenge sites, as usual, but also multiple multiform lesions developed over the entire dorsum after healing of the primary lesions. Taking into account the fact that abolishment of the cell-mediated response led to an aggravated course of the syphilitic infection, the results of these experiments were interpreted as indicating the protective role of the cell mediated response in syphilis.

Animals↗
PubMedDate not supplied

Interaction of adenosine analogs with morphine in analgesic tests.

The effect of selective adenosine receptor agonists on nociceptive responses of mice and rats and on morphine analgesia was investigated. All compounds used: phenylisopropyladenosine (R-PIA), adenosine ethylcarboxamide (NECA), cyclohexyladenosine (CHA) and 2-chloroadenosine (2-CADO) exhibited antinociceptive action in mice and rats in the hot-plate (56 degrees C) and tail-immersion (52 degrees C) tests. R-PIA, CHA and NECA potentiated the antinociceptive action of morphine in mice, and R-PIA and NECA--in rats. 2-CADO did not affect the morphine action in the tests.

2-Chloroadenosine↗
PubMedDate not supplied

The effect of adenosine receptor agonists on analgesic effects of morphine.

The effect of adenosine, S-phenylisopropyladenosine (S-PIA) and dipyridamole (an adenosine reuptake inhibitor) on the analgesic action of morphine in mice and rats was investigated in the hot-plate (56 degrees C) and tail immersion (52 degrees C) tests. Adenosine, 50 and 100 mg/kg, induced analgesia in mice and rats in the hot-plate test and potentiated the action of morphine (particularly in mice). The analgesic effects of adenosine were completely abolished by caffeine (10 mg/kg in mice and rats), and partially inhibited by naloxone (1 mg/kg, only in mice). S-PIA given alone (0.6 mg/kg) produced in mice some analgesic effect in the hot-plate test: the effect was abolished by caffeine and partially by naloxone. The effect of S-PIA on the action of morphine depends on the dose and the animal species. Dipyridamole alone did not affect the reactivity of animals in tests for analgesia, but potentiated the action of morphine.

Adenosine↗
PubMedDate not supplied

The effect of methylxanthines on morphine analgesia in mice and rats.

The influence of various doses of caffeine and theophylline on analgesic effect of morphine was tested in mice and rats in the hot plate and tail immersion tests. Caffeine in rats potentiated the morphine analgesia in both tests in a dose-dependent manner. In mice the caffeine-morphine interaction was biphasic: lower caffeine doses (10 and 25 mg/kg) inhibited, while higher (75 and 100 mg/kg) potentiated the analgesic effects of morphine. Theophylline interacted with morphine in a manner similar to that of caffeine.

Animals↗