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Biomedical subjects

B Jakoubek

Publications and source records attributed to B Jakoubek.

At least 37 records · Page 2Linked to original sources
PubMed1978

Developmental changes of protein-bound radioactivity distribution in rat brain slices incubated with labelled leucine.

The distribution of protein-bound labelled leucine in cortical slices prepared from young rats was investigated by autoradiography and complemented with measurements of the rate of protein synthesis in slices. During the second and third postnatal weeks the rate of protein synthesis in cortical slices from rat brain declined rapidly. The distribution of protein-bound radioactivity was fairly homogenous within the neuronal cell population of cortical slices from 7-day-old rats and was not influenced by the level of labelled leucine in the incubation medium (0.01 and 1 mM). On the contrary, the gradient-like distribution of incorporated radioactivity appeared in slices from 14-day-old rats, at both trace and 1 mM levels of the precursor. The laminar analysis of neuronal cell labelling confirmed the preponderance of incorporation into the neurones localized near the slice surface and the considerable inhibition of neuronal protein synthesis in the slice centre. Therefore, these limitations on the use of cortical slices for the study of brain protein synthesis in the rat should be respected from the beginning of the second postnatal week.

Age Factors↗
PubMed1977

Do hormonal (stress) and vascular (ischaemia) factors contribute to reflex muscle atrophy induced by chronic nociceptive stimulation in rats?

1. Reflex muscle atrophy was induced in rats by fracturing the metatarsal bones of one hind paw and injecting 0.02 ml turpentine oil into the planta under shortlasting ether anaesthesia. The atrophy thus evoked in the soleus and extensor digitorum longus (EDL) was compared with the contralateral muscles. 2. There was a twelvefold increase of plasma corticosteroid levels one hour after application of the above nociceptive stimulus and the levels were still somewhat enhanced at 3 days. Neither bilateral adrenalectomy nor administration of corticosteroid hormones or cold stress affected the development of reflex atrophy. 3. Restriction of the arterial blood supply (ligature of the common iliac artery) led to a slowly progressing atrophy with a maximum 10 days after the ligature. Reflex atrophy introduced at different times after ligature was not enhanced. 4. These results are interpreted as evidence that neither general stress (and the effect of catabolic hormones) nor local restriction of muscle blood flow (by reflex vasospasm, for example) are likely to play any appreciable role in the mechanism of reflex muscle atrophy.

Adrenal Cortex Hormones↗
PubMed1976

Incorporation of 4,5-3H leucine into the neurons of locus ceruleus and other nerve cells in stressed rats: effect of diazepam.

Incorporation of 4,5-3H leucine into neurons of locus ceruleus, neurons of the terminal principal nucleus of the trigeminal nerve and spinal moto-neurons in stressed rats (S group), animals, stressed after a single injection of diazepam (DS group), and controls (C group) was studied by quantitative autoradiography. Both in the S and DS groups the planimetrically measured neuronal areas were bigger than in the C group of spinal motoneurons and trigeminal neurons. Stress, however, had no effect on the size of neurons in locus ceruleus. No significant differences of grain density among C and S group were found in the three investigated neuronal groups; diazepam pretreatment (DS group), however, increased markedly the grain density in all types of neurons investigated.

Animals↗
PubMed1976

Topographical differences of RNA labelling in rat brain after intraventricular administration of labelled RNA precursors.

14C-uridine or 14C-orotic acid was injected into the third or fourth brain ventricle of adult rats. The rate of incorporation of these precursors into the RNA of various brain regions was studied by autoradiography. 0.5 hour, 1 hour, 2 hours and 4 hours after the injection of labelled uridine and/or orotic acid into the third ventricle, a very uneven labelling of different brain regions was observed. The highest grain density was found over the ventricular walls and in the closely adjacent brain tissue; the intensity of labelling decreased sharply with distance from the ventricular lumen. 24 hours after intraventricular injection, a medio-lateral gradient of grain density was no longer observed. An intense labelling of leptomeninx (especially at the base of the brain) and of ependymal cells was observed at all time intervals investigated. At time intervals 0.5-2 hours the grain density of these structures surpassed by a considerable amount the grain density over neurona, glial cells or neuropile. Two hours after the injection of 14C-orotic acid into the fourth ventricle, the grains were mainly localised over leptomeningeal cells and vessels at the base of the brain and in the adjacent narrow strip of brain tissue. The rest of the brain was only very faintly labelled.

Animals↗
PubMed1976

Distribution of protein-bound radioactivity in brain slices of the adult rat incubated with labelled leucine.

The distribution of protein-bound labelled leucine in brain cortex slices, prepared from adult rats by various methods and incubated with [14C]- or [3H]leucine, was investigated by autoradiography. In the first and second slices a marked gradient of incorporated radioactivity from the cut surface to the slice interior was observed. Very high labelling of leptomeningeal cells and vessels enhanced further the inhomogeneity of radioactivity distribution. Light microscopic examination of incubated slices revealed morphological alterations of neurones, especially in the vicinity of the cut surface. The comparison of grain density over neurones and their satellite glia indicated markedly higher incorporation into the latter. The ATP level in slices at the end of incubation reflected the method of slice preparation and morphological integrity. Inhomogeneity of incorporated radioactivity distribution in brain slices contrasted with the uniform labelling of cortical cells in vivo, and may represent at least one reason for the low estimates of protein synthesis rate in brain cortex slices.

Adenosine Triphosphate↗
PubMed1976

The effect of ACTH and diazepam on the uptake of tritiated uridine into brain, muscles and liver of infant rats.

In 2-day-old rats, ACTH increases the uptake of 3H-uridine in the brain; no such effects were observed in the msucle and liver tissue. Diazepam does not affect the uptake of 3H-uridine into the brain tissue, but decreases the uptake into the muscle tissue. In the brain tissue of infant rats, ACTH does not change the distribution of radioactivity of intraperitoneally administered 3H-uridine among U, Urd, UMP, UDP and UTP. Diazepam increases the amount of radioactivity, found at the U spot. In the muscle, both ACTH and Diazepam increases the amount of radioactivities found in the Urd spot. A significant correlation between the radioactivity of UMP+UDP+UTP and the specific activity of RNA was proved only in the brain. The ratio: specific activity of brain RNA/radioactivity of UMP+UDP+UTP was thus used as a tentative indicator of the biosynthesis of brain RNA. Neither ACTH nor diazepam altered this ratio in infant rats.

Adrenocorticotropic Hormone↗