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Biomedical subjects

M Buresová

Publications and source records attributed to M Buresová.

At least 19 recordsLinked to original sources
PubMed1993

Maintenance of a circadian phase adjustment of the human melatonin rhythm following artificial long days.

In winter, a 5-day exposure of 4 human subjects to a skeleton photoperiod, with 3 h of bright light in the evening and again in the morning, phase advanced the morning serum melatonin offset by 1-3 h as compared with the original winter melatonin rhythm pattern. The phase advance persisted for 3 days even after the bright light withdrawal. The data indicate that the long skeleton photoperiod had a prevailing phase-advancing effect on the melatonin rhythm and its underlying pacemaker. The maintenance of the phase advance might be due to the fixed sleep-wake schedule.

Adult↗
PubMed1993

Melatonin rhythm in human milk.

The pineal hormone melatonin exhibits a circadian rhythm in body fluids. No data are available on melatonin in human milk. The present study was undertaken to determine whether melatonin is detectable in human milk and, if so, whether it exhibits a daily rhythm. Blood and milk were sampled between 1400-1700 h and again between 0200-0400 h from 10 mothers 3-4 days after delivery. Melatonin in both fluids was beyond the limit of detection during the day, whereas during the night, its concentration was 280 +/- 34 pmol/L in serum and 99 +/- 26 pmol/L in milk. Six mothers collected milk after each feeding throughout 1 24-h period within 3 months after delivery. Melatonin in the milk of all subjects exhibited a pronounced daily rhythm, with high levels during the night and undetectable levels during the day. The presence of the rhythm in milk suggests that melatonin fluctuations in milk might communicate time of day information to breast-fed infants.

Adult↗
PubMed1992

Human circadian rhythm in serum melatonin in short winter days and in simulated artificial long days.

Serum melatonin rhythm was studied in 6 human subjects experiencing short winter days resembling light/dark (LD) 8:16 h and in 6 subjects exposed at the same time to a long, LD 16:8 h skeleton photoperiod, with 3 h of bright light in the evening and again in the morning; 4 out of the 6 subjects entrained to the simulated summer photoperiod within 3 days. In the synchronized subjects, the nocturnal melatonin signal was 3 h shorter than in those experiencing just winter days. The data indicate that humans are able to respond to environmental day length by forming a proper endogenous photoperiodic signal.

Adult↗
PubMed1991

Early morning bright light phase advances the human circadian pacemaker within one day.

One day after a single exposure to bright light from 03.00 to 09.00 h the morning declines in the serum melatonin concentration were phase-advanced in all subjects relative to pre-exposure patterns by 1.2-2.6 h. The evening melatonin rise was phase-advanced in 5 out of 6 subjects by 0.6-2.2 h. The data suggest that an underlying human circadian pacemaker controlling the melatonin rhythm may be phase-advanced within one day; however, the evening melatonin rise and the morning decline do not necessarily phase-shift by the same amount.

Circadian Rhythm↗
PubMed1991

The assessment of the behavioural teratogenic risk of the tocolytic drug phenoterol.

Phenoterol, a tocolytic drug widely used in cases of imminent preterm labour for disruption of uterine contractions, was studied for potential harmful impact on the developing fetal brain which is just going through the vulnerable period of accelerated histogenesis and cytodifferentiation. As the developmental stage of human fetus brain in late pregnancy closely resembles the ontogenetic phase of the rat brain in the early postnatal period, the model experiments were carried out using the drug administration in the neonate rat and life-long comprehensive follow-up of sequels in behaviour, reproductive functions and brain biochemical parameters. No deviations were found when phenoterol was administered in the dose 1 mg/kg/day s.c. on the postnatal days 6-9 (clinically relevant dosage). Several minor aberrations were observed after 10 times higher dose (10 mg/kg/day s.c. on postnatal days 5-7) in preweaning period (acceleration of somatic development) and in adulthood i.e. at the age of 2-7 months (higher score of emotionality). The inferiority of phenoterol treated rats became apparent only with the onset of senescence (age 11-14 months) when lower score of memory acquisition was ascertained joined with an increase of lipid peroxidation in the brain cortex.

Animals↗
PubMed1985

Model studies of perinatal insults: a comprehensive approach to behavioural teratology.

The perinatal brain provides a vulnerable target for many noxious insults that interfere--according to their intensity, specificity and timing--with morphogenetic (cell proliferation, migration, association and programmed cell death) and functiogenetic (axogenesis, dendrogenesis, synaptogenesis and myelination) processes. The disturbance of brain cells and/or disorganization of their connections give rise to structural, biochemical and functional pathology most frequently detected in the form of behavioural deviations. For the study of behavioural teratogenicity of perinatal malnutrition, protein synthesis alteration and glucocorticoid administration--all being also important clinically--metabolic, cytotoxic and receptor-mediated models have been designed. The longitudinal follow--up of morphological, neurochemical, endocrine, reproductive, and behavioural changes proved to be valuable for the elucidation of pathogenetic mechanisms as well as for the evaluation of pharmacological influences preventing maldevelopment of the brain.

Animals↗
PubMed1984

The neonatal cerebellum: the highest level of glucocorticoid receptors in the brain.

We investigated the postnatal development of glucocorticoid receptors (GR) in rat cerebral cortex, hippocampus, olfactory bulbs and cerebellum during a period when cell proliferation, including neurogenesis in the latter 3 brain parts, is intensive. The concentration of GR was determined as the specific binding of [3H]dexamethasone to the cytosol stabilized against the inactivation of unoccupied receptor molecules by sodium molybdate. Unoccupied GR levels were found to increase during the first week, most rapidly in the cerebellum, where it reached the maximum during the second week. Specific binding of [3H]dexamethasone to the cerebellar nuclear fraction has already been present at days 8 and 15. By the end of the second week the cytosolic unoccupied GR begin to decline in the cerebellum. Total receptor binding, however, estimated in adrenalectomized animals does not decline. On the other hand, at day 8 adrenalectomy did not reveal more receptors than obtained in intact animals. Large numbers of GR in the neonatal cerebellum may specifically mediate the adverse effects of glucocorticoids on the cerebellar development during the period when the intensive morphogenetic processes take place in this part of the brain.

Animals↗
PubMed1979

[Adenoidectomy].

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Adenoidectomy↗
PubMed1978

Effect of M.bovis BCG and M.microti on sarcoma 180 growth in mice.

The antitumorous efficacy of the Czechoslovak BCG 725, Czechoslovak BCG 901, the Danish SAS maintained, the Japanese SAS and SH maintained BCG strain and the Czechoslovak OV 247 (M.microti) strain was studied. (SAS--original Sauton's medium with asparagine, SH--Sauton's medium with the asparagine replaced by enzymatic casein hydrolysate.) Ascitic Sa 180 cells were used as the experimental tumor and 800 mice as experimental animals. All the strains employed displayed an anticarcinogenic effect in a protective assay (immunization 8 weeks before inoculation of Sa 180 cells). In a therapeutic test (vaccine administered 24 hr after inoculation of Sa 180 cells and then at weekly intervals), Czechoslovak BCG 725 and Czechoslovak OV 247 were used and proved effective.

Animals↗
PubMed1975

Changes of ribosomal capacity for protein synthesis, contraction and histochemical properties of muscle after implantation of fast nerve into denervated and into self-reinnervated slow soleus muscle of the rat.

The ribosomal capacity for protein synthesis in the fast extensor digitorum longus muscle of the rat is markedly higher than in the slow soleus muscle. Implantation of the "fast" peroneal nerve into the denervated or into the self-reinnervated soleus muscle results in transformation (increase) of capacity of isolated ribosomes for protein synthesis into that of the fast muscle type. The degree of transformation is higher after implantation into the self-reinnervated than into the denervated soleus muscle. A high degree of recovery of weight and tetanic tension output is recorded after the "fast" nerve implantation. The effect of transformation with respect to contraction properties is considerably more marked in the case of heteroinnervation of the denervated muscle and persists even after 5 months of heteroinnervation. Transformation of the histochemical muscle fibre pattern is also more pronounced after heteroinnervation of the denervated than self-reinnervated soleus muscle; the muscle acquires the fibre pattern of the fast extensor digitorum longus muscle. The acquisition of the reciprocal pattern of oxidative and glycolytic enzymes suggests that the activation of protein synthesis induced by the foreign "fast" nerve supply is coupled with the operation of specific RNA species.

Animals↗