Retinol-induced changes in the phosphorylation levels of histones and high mobility group proteins from Sertoli cells.

Chromatin proteins play a role in the organization and functions of DNA. Covalent modifications of nuclear proteins modulate their interactions with DNA sequences and are probably one of the multiple factors involved in the process of switch on/off transcriptionally active regions of DNA. Histones and high mobility group proteins (HMG) are subject to many covalent modifications that may modulate their capacity to bind to DNA. We investigated the changes induced in the phosphorylation pattern of cultured Wistar rat Sertoli cell histones and high mobility group protein subfamilies exposed to 7 microM retinol for up to 48 h. In each experiment, 6 h before the end of the retinol treatment each culture flask received 370 KBq/ml [32P]-phosphate. The histone and HMGs were isolated as previously described [Moreira et al. Medical Science Research (1994) 22: 783-784]. The total protein obtained by either method was quantified and electrophoresed as described by Spiker [Analytical Biochemistry (1980) 108: 263-265]. The gels were stained with Coomassie brilliant blue R-250 and the stained bands were cut and dissolved in 0.5 ml 30% H2O2 at 60oC for 12 h. The vials were chilled and 5.0 ml scintillation liquid was added. The radioactivity in each vial was determined with a liquid scintillation counter. Retinol treatment significantly changed the pattern of each subfamily of histone and high mobility group proteins.

Does coupling of uterine contractions reflect uterine dysfunction?

In a cohort analytical study 47 primigravidas in spontaneous normal labour at term were divided into two groups depending on the presence or absence of coupled uterine contractions during active labour. During monitoring with a pressure-tip intra-uterine catheter, 24 patients developed coupled contractions and 23 had a normal contraction pattern. There were no statistically significant differences between the two groups with regard to maternal age, gestational age, maternal height, fetal weight, head circumference and pelvic size. Patients who developed coupled contractions had a longer duration of labour, a higher uterine activity integral and an increased incidence of caesarean section for failure to progress. Because coupling of uterine contractions may be indicative of dysfunctional uterine activity, and hence a prolonged first stage of labour, failure to progress during labour in these patients should be interpreted with caution in order to avoid the incorrect diagnosis of cephalopelvic disproportion.

Obstetrical condition and neonatal neurological outcome in Dominica, the Caribbean. A comparative study.

Risk factors during pregnancy and delivery and neurological morbidity of newborns were assessed in a birth cohort in Dominica, the Caribbean. The data were compared with two reference groups, one from Grenada, the Caribbean, and the other from Groningen, the Netherlands. Despite variations in cultural and socio-economic situation, the similarities in obstetrical conditions, neonatal neurological morbidity and perinatal relationships between the three groups were more striking than the differences. The Dominican group showed a significantly higher rate of preterm births than the two other groups. Preterm birth was associated with a significant increase in neurological deviancy. In general motility and muscle tone were found to be lower in the Caribbean region than in the Netherlands.

Retinol-induced changes in the phosphorylation levels of histones and high mobility group proteins from Sertoli cells

Chromatin proteins play a role in the organization and functions of DNA. Covalent modifications of nuclear proteins modulate their interactions with DNA sequences and are probably one of the multiple factors involved in the process of switch on/off transcriptionally active regions of DNA. Histones and high mobility group proteins (HMG) are subject to many covalent modifications that may modulate their capacity to bind to DNA. We investigated the changes induced in the phosphorylation pattern of cultured Wistar rat Sertoli cell histones and high mobility group protein subfamilies exposed to 7 µM retinol for up to 48 h. In each experiment, 6 h before the end of the retinol treatment each culture flask received 370 KBq/ml [32P]-phosphate. The histone and HMGs were isolated as previously described [Moreira et al. Medical Science Research (1994) 22: 783-784]. The total protein obtained by either method was quantified and electrophoresed as described by Spiker [Analytical Biochemistry (1980) 108: 263-265]. The gels were stained with Coomassie brilliant blue R-250 and the stained bands were cut and dissolved in 0.5 ml 30 per cent H2O2 at 60oC for 12 h. The vials were chilled and 5.0 ml scintillation liquid was added. The radioactivity in each vial was determined with a liquid scintillation counter. Retinol treatment significantly changed the pattern of each subfamily of histone and high mobility group proteins.