PubMed Health⌕ Search

Biomedical subjects

I Balla

Publications and source records attributed to I Balla.

17 recordsLinked to original sources
PubMed1990

Sustained stimulation of aldosterone production by angiotensin II is potentiated by nickel.

Angiotensin-induced aldosterone production by superfused adrenal glomerulosa cells was potentiated by Ni2+ (0.1 mM), added either at the onset of stimulation with angiotensin II or 1 h later. Nickel did not influence the effect of adrenocorticotropic hormone or potassium on aldosterone production. Nickel failed to modify angiotensin-induced changes in phospholipid metabolism or the formation of inositol phosphates and slightly reduced the enhancement of 45Ca influx. Uptake of Ni2+ into glomerulosa cells was increased by depolarization in a dihydropyridine-insensitive manner. Because nickel selectively potentiates the sustained phase of the response to a calcium-mobilizing hormone, it may serve as a suitable tool in elucidating the signal transduction process during the sustained phase of stimulation.

Aldosterone↗
PubMed1989

Lectinhistochemical study of cell surface alterations in mouse embryos exposed to low radiation doses.

The peroxidase-coupled Dolichos biflorus agglutinin (DBA) served as a marker for cell surface alterations in embryonic mouse tissues exposed to low-dose radiation during the early organogenesis (day 9 post conception). In unirradiated embryos, DBA bound selectively to various organ primordia, depending on their differentiation state. The auditory vesicles and the developing blood vessels were the only tissues staining strongly with the lectin. The vascular endothelia also showed the highest radiosensitivity, expressed by the maximal reaction already at 12.5 cGy. Marked surface changes as well were registered in the basal part of the Rathke's pocket and in the roof of the diencephalon. After exposure to 25 cGy, a transient amplification of the reaction as compared with 12.5 cGy occurred firstly in the Rathke's pocket, then in the infundibulum and in auditory vesicles. The most distinct effects were achieved with 50 cGy. Remarkable is the prompt rise of the DBA-affinity in a narrow area of the myelencephalon, and subsequently also in the roof of the diencephalon. Furthermore, the infundibulum and the Rathke's pocket, both anlagen of the pituitary gland, bound heavily DBA during the entire examination period of 24 h. The present study demonstrated the outstanding suitability of the Dolichos biflorus agglutinin for histochemical detection of subtle cellular alterations by small radiation doses.

Animals↗
PubMed1989

Angiotensin II and potassium activate different calcium entry mechanisms in rat adrenal glomerulosa cells.

Initial 45Ca uptake was measured in isolated rat glomerulosa cells. A small reduction in membrane potential produced by increasing the K+ concentration from 2 to 3.6 mmol/l stimulated 45Ca uptake by about 35%, while a bigger depolarization induced by 18.5 mmol K+/l increased the uptake by about 100%. Since Ca2+ influx was already activated at a calculated membrane potential below -70 mV, and was found to be sensitive to the dihydropyridine antagonist nifedipine (1 mumol/l), but insensitive to nickel ions (100 mumol/l), it does not meet the criteria established for T- or L-type voltage-dependent Ca2+ channels. Exposure of glomerulosa cells to angiotensin II (AII) for 10 min also enhanced the rate of 45Ca influx. The effect of AII was not sensitive to 1 mumol nifedipine/l, but was strongly inhibited by 5-(N-4-chlorobenzyl)-N-(2',4'-dimethyl)benzamil (CBDMB, 30 mumol/l), an inhibitor of the Na+/Ca2+ antiporter. These observations suggest that during the sustained phase of stimulation with AII, a CBDMB-sensitive mechanism, rather than dihydropyridine-sensitive calcium channels, is involved in Ca2+ uptake in rat glomerulosa cells. The bulk Ca2+ influx did not correlate with aldosterone production; however, the maintained activity of different Ca2+ entry mechanisms seems to be essential for AII-induced aldosterone production.

Aldosterone↗
PubMed1988

Na+-H+ and Na+-Ca2+ exchange in glomerulosa cells: possible role in control of aldosterone production.

Sodium uptake by rat adrenal glomerulosa cells was stimulated by intracellular acidosis evoked by Na+-propionate. This process was inhibited by 5-(N,N-hexamethylene) amiloride (HMA), a known inhibitor of the Na+-H+ exchange. These experiments demonstrate the existence of the Na+-H+ exchange in glomerulosa cells. Although amiloride inhibited the angiotensin II- and adrenocorticotropic hormone (ACTH)-induced aldosterone response, HMA, a more specific inhibitor of Na+-H+ exchange, failed to do that. 45Ca2+ influx and efflux were dependent on intra- and extracellular Na+ concentrations. Amiloride analogues, known to inhibit Na+-Ca2+ exchange, reduced basal 45Ca influx. Although we could not reveal the activation of Na+-Ca2+ exchange by angiotensin II, inhibitors of Na+-Ca2+ exchange also inhibited the angiotensin- and ACTH-induced aldosterone response of glomerulosa cells. Our results suggest that Na+-Ca2+ exchange supports the maintenance of basal Ca2+ level in the cytoplasma of glomerulosa cells, and amiloride derivatives inhibit aldosterone production by reducing Ca2+ level below resting values.

Adrenal Glands↗
PubMed1987

Interaction between radiation and cadmium or mercury in mouse embryos during organogenesis.

The response of mouse embryos to different concentrations of cadmium or mercury with or without low LET radiation was measured in terms of gross morphological anomalies and cellular changes. Single doses of the heavy metals (2 mg/kg body weight) were injected i.p. on day 8 of gestation 30 min before whole-body irradiation. Combined exposures to CdCl2 and X-rays led to a significant reduction in the rate of exencephaly compared with the high frequency after cadmium alone. The hypothesis that metallothionein, a sulphur-rich and metal-binding protein, may be responsible for the antagonism observed could not be confirmed. Mercuric chloride alone induced a low rate of exencephaly and the data on combined treatment suggest additivity with 0.5 and 1.0 Gy X-rays. Regarding cellular criteria, cell death in the eye anlage on day 9 of gestation was significantly suppressed after 0.5 Gy and especially after CdCl2 plus 0.5 Gy compared to cadmium alone. It is assumed that the reduction of cell lethality is correlated with the low occurrence of exencephaly. Concerning the proliferation of neuroblasts, cadmium stimulated the mitotic activity whereas X-rays depressed the proliferation capacity. After the combined treatment a distinct antimitotic effect was established.

Abnormalities, Drug-Induced↗
PubMed1987

Synergistic interaction between vindesine and X-rays in the prenatal development of mice.

The modification of radiation damage by various concentrations of the oncolytic drug vindesine was studied macroscopically, using mouse embryos during the early organogenesis (days eight and nine of gestation) as the test system. The analysis at term showed that the developmental toxicity of vindesine depends on the dosage and the time of administration. In the lower dose-range (0.25 and 0.35 mg/kg), the only reaction was growth retardation, whereas higher concentrations (0.5 and 1.0 mg/kg) led mainly to an early resorption of implants. The more differentiated stage (day nine) exhibited a much higher sensitivity to vindesine than the embryo on day eight. Conversely, the harmful action of 0.9 Gy X-rays was restricted to the earlier period of organogenesis. The incidence of abnormalities after irradiation on day eight was 4.5 times higher than the one following exposure on day nine. The combined exposures showed a radiosensitizing capacity of the drug with respect to the teratogenic response on day eight only. The pretreatment with 0.25 mg/kg vindesine potentiated the radiation-induced malformation rate by a factor of 1.7, and the one with 0.35 mg/kg vindesine by a factor of 2.4.

Abnormalities, Drug-Induced↗
PubMed1983

Cellular damage and recovery of the early developing mouse eye following low dose irradiation. II. X-rays on day 9 of gestation.

Mouse embryos on day 9 of gestation were exposed in utero to 90 rad X-rays. At different time intervals after treatment the eye primordia were examined for cell death. The irradiation caused an altered necrosis pattern compared with day 8, and massive cell killing during a limited time period. The rapid recovery from the pronounced damage points to a high restitution efficiency of the involved tissue.

Animals↗
PubMed1980

[Central fractures of the talus (author's transl)].

The results of the analysis of 52 central talar fractures and 37 follow-up cases in the 10 year material of the National Institute of Trauma are reported here. They point to the fact, that osteoarthritis can be avoided by appropriate treatment. Two aetiological factors in arthritis are the residual joint surface incongruence and the damage to the blood supply. Immediate, exact reduction and retention, even operatively if necessary and the delay of weight bearing until the restoration of blood supply and the bony architecture are recommended as preventive measures. If doubt arises on the diagnosis of damaged blood supply, intraosseous venography is recommended.

Adolescent↗
PubMed1979

[Dislocations of the talus (author's transl)].

Authors analysing 31 case histories of talus fractures and following the results in 22 cases over a period of 3--12 years support the general view, that the healing of such injuries is satisfactory but partial or even total necrosis may occur. They emphasize the importance of X-ray investigation and occasional phlebography in order to clear up the state of circulation in the bone. Weight bearing should be decided in accordance with these examinations.

Adolescent↗
PubMed1977

[Phlebography in fractures and dislocations of the talus (author's transl)].

Late osteonecrosis and/or osteoarthrosis occurs frequently after dislocation and fracture dislocation of the talus. The cause seems to be a primary vascular lesion additionally to the initial damage of bone and cartilage and subsequent joint incognity. We recommended phlebography 3 to 6 months after injury for the proof or exclusion of a vascular lesion. Our experience with this method has been encouraging.

Adult↗
PubMed1977

[Diagnosis and treatment of postoperative infections following hip injuries].

The authors studied the diagnosis and treatment of posttraumatic infections of the hip joint, based on their own material. In case of latent infection the increased sedimentation rate and taking of comparative X-ray films are held important, that shows a narrowing and disappearance of the sclerosed edge of the acetabulum. Following dislocation of the hip joint ankylosis may be attained, but after fractures of the proximal and of the femur the infection cannot be cured, unless the nail and the head of the femur are removed.

Adult↗