Nitric oxide enhances amino acid release from immature chick embryo retina.

Nitric oxide (NO) was investigated for its ability to induce amino acid release from immature chick retina. The production of endogenous NO by activation of NO synthase after stimulation of N-methyl-D-aspartate (NMDA) subtype of glutamate receptor caused a significant increase in basal release of gamma-aminobutyric acid (GABA) and glutamine, whereas a more modest increase in the glutamate release was also observed. The exposure of chick retina from 9-day-old embryos to NO-generating compounds, S-nitroso-N-acetylpe-nicillamine (SNAP) and sodium nitroprusside (SNP) produced a dose dependent increase in GABA, glutamine, and glutamate release. This effect was reduced by about 80% by haemoglobin. These results indicate that NO has a stimulatory effect on amino acid release from chick embryo immature retina. However, this effect does not appear to involve a cGMP-related mechanism because 8-bromo-cGMP, a stable analogue of cGMP, failed to affect spontaneous amino acid release and because zaprinast did not enhance NMDA-stimulated release. In conclusion, our present observations may account for a role of NMDA-mediated events in the biochemical maturation under depolarizing conditions.

[The role of prolonged cardiac pacing in management of secondary bradyarrhythmias based on personal experiences]. / Miejsce przewleklej stymulacji elektrycznej serca w leczeniu wtórnych bradyarytmii na podstawie wlasnych spostrzezen.

Three patients with bradyarrhythmia who were admitted to the Department for urgent pacemaker implantations are presented. The careful clinical evaluation revealed that these arrhythmias were remarkably secondary to underlying diseases (e.g. severe coronary heart disease, valvular defects). Surgical treatment applied in these cases (coronary bypass grafts, valve replacement) has resulted in successful outcome. We concluded that in some patients the pacemaker implantation alone, without heart surgery, would not be beneficial enough.

Nitric oxide synthase in chick embryo retina during development.

High levels of nitric oxide synthase were found in the early stages of developing chick embryo retina. The enzyme activity sharply decreased up to 13-day-old chick embryo retina, when the level of the last embryonic day was reached. The results show that nitric oxide is synthesized in chick embryo retina prior to synaptogenesis. The incubation of chick embryo retinas in presence of NMDA increased the synthesis of nitric oxide, thus, the appearance of nitric oxide production before the synaptogenesis in the retina as well as in the brain may be considered as signal for the development and shaping of neuronal and non-neuronal cells.

Intradialytic erythrocyte volume changes.

Haemodialysis (HD) should affect the erythrocytes, which constitute more than 99% of blood cells. The aim of this study was to reinvestigate the intradialytic changes in erythrocyte water content (MCV). MCV was measured during 81 HD (47 uncomplicated, 34 with hypotension), and 16 isolated ultrafiltrations (UF) performed in stable, haemodialysed adults (12 males and 8 females). The MCV following uncomplicated HD (n = 32) did not differ from the predialysis value. Significant MCV increase accompanied the HD initiation (4.9 +/- 9.0 fl, P less than 0.001), UF (2.99 +/- 1.49 fl, P less than 0.001) and hypotension (1.8 +/- 3.1 fl, P less than 0.01). This was independent of sodium and potassium within the cells and plasma. Erythrocyte oedema occurred in situations known to accompany both bioincompatibility reactions and blood volume decrease. Intradialytic MCV increase may reflect a response to these events, possibly hormonal, and needs further investigation.

[Observations of pharmacological blockade of atrioventricular conduction in patients with long-term ventricular pacing type VVI]. / Obserwacje nad blokowaniem farmakologicznym przewodzenia komorowo-przedsionkowego u chorych z przewlekla stymulacja komorowa typu vvi.

In a group of 19 patients with implanted ventricular on demand pacemaker (VVI) with presence of ventriculo-atrial conduction (VAC) 1:1 blockade of this retrograde conduction was achieved in 9 cases (47.4%). The effective drug injected intravenously was verapamil, which could be used in abortive pacemaker syndrome.

Granulocyte viability test in children from an environment with heavy metal pollution.

In a group of 43 school-children living near a zinc plant, the test of granulocyte viability by the method of Cocchi et al, the lead level by flame atomic absorptiometry, and the level of erythrocyte zinc-protoporphyrin by the fluorimetric method were determined in peripheral blood. The mean result of the granulocyte viability test was 6.49%. In 18 children, the proportion of abnormal granulocytes was raised abnormally above 6.0%. The lead level was in the range from 14.1 to 53 micrograms/dl, and the level of erythrocyte ZPP was from 0.3 to 2.1 micrograms/g Hb. No correlation was found between the results of the granulocyte viability test and the blood lead level. The result of a comparison with the ZPP value was of borderline significance (p = 0.05).

Cyclic 3',5'-adenosine monophosphate (cAMP) in a 42-month-old child with clinical evidence of multiple hormonal disturbances.

In a boy aged 42 months, small stature, retarded psychomotor development, dry skin, excessive thirst, polyuria, cryptorchidism, and rickets were signs of multihormonal disturbances. Contrary to the clinical manifestations, laboratory investigations showed normal or raised levels of hormones (hGH, insulin, T3RU, T4, TSH, PTH). The cAMP level in the plasma was low and its urinary excretion was reduced. After administration of hGH, adrenaline, T3, T4, pitressin, vitamin D3 and aminophylline there was no rise in the cAMP concentration in plasma and urine. In the light of these results it may be assumed that deficient function of the adenyl cyclase system led to development of a clinical syndrome of tissue insensitivity to multiple hormonal factors in this case.