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001-es BibID:	BIBFORM046876
Első szerző:	Berényi Ervin (radiológus)
Cím:	Water Content and Proton Magnetic Resonance Relaxation Times of the Brain in Newborn Rabbits / Berényi Ervin, Repa Imre, Bogner Péter, Dóczi Tamás, Sulyok Endre
Dátum:	1998
ISSN:	0031-3998
Megjegyzések:	The present study, using proton nuclear magnetic resonance relaxation (H1 NMR) measurements, was undertaken to quantitate water fractions with different mobility in the brain tissue obtained form New Zealand White rabbit pups. Serial studies were carried out at the postnatal age of 0-1, 24, 48, 72, and 96 h in pups nursed with their mothers and suckling ad libitum (group I) and in those pups separated from their mothers and completely withheld from suckling (group II). Tissue water content (desiccation method) and T1 and T2 relaxation times (H1 NMR method) were measured. Free, loosely bound, and tightly bound water fractions were calculated by applying multicomponent fits of the T2 relaxation curves. It was demonstrated that brain water content and T1 and T2 relaxation times did not change with age in the suckling pups. In pups withheld from suckling brain water decreased from 89.4 +/- 0.5% at birth to 87.7 +/- 0.1% at the age of 96 h (p < 0.05), T1 remained unchanged, and there was a significant fall in T2 by the age of 72 h (188 +/- 12 versus 178 +/- 4 ms, p < 0.05) and 96 h (171 +/- 6 ms, p < 0.01). Partition of brain water into bound and free fractions as derived from biexponential fits of T2 decay curve showed that the percent contribution of bound water fraction in pups of group I fell progressively from 61% at birth to 3% at the age of 72-96 h (p < 0.05). This fall was accelerated by the complete deprival of fluid intake, and the level of about 4% could be attained as early as the age of 24 h. Triexponential analysis of T2 relaxation curves revealed that the loosely bound fraction (middle component) predominated over the free (slow component) and the tightly bound (fast component) water fractions. In response to withholding fluid intake, the free water fraction increased 4-fold at the expense of tightly bound brain water. It is concluded that the majority of neonatal brain water is motion-constrained. The free, the loosely bound, and the tightly bound water fractions appear to be interrelated; from the brain water store water can be released to supply free water for volume regulation.
Tárgyszavak:	Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:	Pediatric Research. - 43 : 3 (1998), p. 421-425. -
További szerzők:	Repa Imre (1950-) (radiológus) Bogner Péter (1963-) (radiológus) Dóczi Tamás Sulyok Endre
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001-es BibID:	BIBFORM016926
035-os BibID:	(WoS)000166385500013 (Scopus)0035165276
Első szerző:	Sulyok Endre
Cím:	Brain water and proton magnetic resonance relaxation in preterm and term rabbit pups : their relation to tissue hyaluronan / Sulyok E., Nyúl Z., Bogner P., Berényi E., Repa I., Vajda Z., Dóczi T., Sedin G.
Dátum:	2001
ISSN:	0006-3126
Megjegyzések:	The present study was performed to investigate simultaneously totalbrain water, T1 and T2 relaxation times, and hyaluronan (HA) in fetaland neonatal rabbits. Attempts were also made to establish therelationship of HA to total brain water and to T2-derived motionallydistinct water fractions, since HA is known to bind water and to limittissue water mobility. Experiments were carried out in fetal Pannonwhite rabbit pups at gestational ages of 25, 27, 29, and 31 days and ata postnatal age of 4 days. The brain tissue water content (desiccationmethod), T1 and T2 relaxation times (H-1-NMR method), and HAconcentration (radioassay HA 50) were measured, and free and boundwater fractions were calculated by using multicomponent fits of the T2relaxation curves. Compared with values in newborn pups, water and HAcontents were found to be highly elevated in the preterm brain anddecreased markedly during early postnatal life. The trends and timecourses of T1 and T2 relaxation times proved to be similar, but thepostnatal decrease in T2 was preceded by a significant decline in lategestation. Maturity-related changes occurred in the T2 relaxationderived bound water fraction which amounted to 4-19% of brain water.The bound water fraction appeared to be independent of total brainwater and HA concentration, and HA is, therefore, unlikely to be theonly factor controlling brain water mobility. The clear dissociation ofbound water fraction from total water suggests restructuring of brainwater during the perinatal period.
Tárgyszavak:	Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk
Megjelenés:	Biology of the Neonate. - 79 : 1 (2001), p. 67-72. -
További szerzők:	Nyúl Zoltán Bogner Péter (1963-) (radiológus) Berényi Ervin (1964-) (radiológus) Repa Imre (1950-) (radiológus) Vajda Zsolt Dóczi Tamás Sedin, Gunna
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001-es BibID:	BIBFORM016928
035-os BibID:	(WoS)000082752600015 (Scopus)0344069638
Első szerző:	Vajda Z.
Cím:	Brain adaptation to water loading in rabbits as assessed by NMR relaxometry / Vajda Z., Berényi E., Bogner P., Repa I., Dóczi T., Sulyok E.
Dátum:	1999
ISSN:	0031-3998
Megjegyzések:	The present study was undertaken to investigate the cerebral adaptationto hypoosmolar stress in adult Pannon white rabbits by applying protonnuclear magnetic resonance relaxometry. Progressive hyponatremia wasinduced by combined administration of hypotonic dextrose in water and8-deamino-arginine vasopressin over a hydration period of 3, 24, and 48h. Each group comprised five animals. After completing the hydrationprotocols, brood was taken to determine plasma osmolality (freezingpoint depression) and sodium concentration (ion-selective electrode)and, at about the same time, T-2-weighted images were made. After thein vivo measurements, the animals were killed and brain tissue sampleswere obtained to measure water content (desiccation method) and T-1 andT-2 relaxation times (proton nuclear magnetic resonance method). Freeand bound water fractions were calculated by using multicomponent fitsof the T-2 relaxation curves. It was shown that brain water content andT-1 relaxation time remained unchanged despite the progressinghyponatremia. By contrast, T-2 relaxation time increased steadily fromthe control value of 100.2 +/- 7.7 ms to attain its maximum of 107.5+/- 8.5 ms (p < 0.05) after 48 h of hydration. Using biexponentialanalysis, fast and slow components of the T-2 relaxation curve could bedistinguished that corresponded to the bound (T-21) and free (T-22)water fractions. In response to hyponatremia, the bound water fractionwas markedly depressed from 6.5 +/- 3.0% to 3.6 +/- 0.9% (3 h, p <0.05) and 3.9 +/- 0.8% (24 h, p < 0.05): then it approached the initialvalue of 5.3 +/- 2.5% by the end of the hydration period of 48 h. It isconcluded that restructuring of brain water is a contributory factor tothe successful adaptation to hypotonic environment.
Tárgyszavak:	Orvostudományok Klinikai orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk
Megjelenés:	Pediatric Research. - 46 : 4 (1999), p. 450-454. -
További szerzők:	Berényi Ervin (1964-) (radiológus) Bogner Péter (1963-) (radiológus) Repa Imre (1950-) (radiológus) Dóczi Tamás Sulyok Endre
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