PubMed Health⌕ Search

Biomedical subjects

S Raboni

Publications and source records attributed to S Raboni.

5 recordsLinked to original sources
PubMed2000

Role of pyridoxal 5'-phosphate in the structural stabilization of O-acetylserine sulfhydrylase.

Proteins belonging to the superfamily of pyridoxal 5'-phosphate-dependent enzymes are currently classified into three functional groups and five distinct structural fold types. The variation within this enzyme group creates an ideal system to investigate the relationships among amino acid sequences, folding pathways, and enzymatic functions. The number of known three-dimensional structures of pyridoxal 5'-phosphate-dependent enzymes is rapidly increasing, but only for relatively few have the folding mechanisms been characterized in detail. The dimeric O-acetylserine sulfhydrylase from Salmonella typhimurium belongs to the beta-family and fold type II group. Here we report the guanidine hydrochloride-induced unfolding of the apo- and holoprotein, investigated using a variety of spectroscopic techniques. Data from absorption, fluorescence, circular dichroism, (31)P nuclear magnetic resonance, time-resolved fluorescence anisotropy, and photon correlation spectroscopy indicate that the O-acetylserine sulfhydrylase undergoes extensive disruption of native secondary and tertiary structure before monomerization. Also, we have observed that the holo-O-acetylserine sulfhydrylase exhibits a greater conformational stability than the apoenzyme form. The data are discussed in light of the fact that the role of the coenzyme in structural stabilization varies among the pyridoxal 5'-phosphate-dependent enzymes and does not seem to be linked to the particular enzyme fold type.

Cysteine Synthase↗
PubMed1992

Cerebral-umbilical Doppler ratio as a predictor of adverse perinatal outcome.

Using a 3.5-MHz duplex Doppler system, 45 normal-growth and 45 growth-retarded fetuses were studied between 30-41 weeks' gestation. Velocity recordings were obtained from the middle cerebral artery and umbilical artery to calculate the ratio between the two pulsatility indexes. The cerebral-umbilical Doppler ratio is usually constant during the last 10 weeks of gestation. Therefore, a single cutoff value (1.08) was used, above which velocimetry was considered normal and below which it was considered abnormal. The cerebral-umbilical Doppler ratio provided a better predictor of small for gestational age newborns and adverse perinatal outcome than either the middle cerebral artery or umbilical artery alone. In fact, in predicting those newborns who were small for gestational age, the cerebral-umbilical ratio had a 70% diagnostic accuracy [(true positive + true negative)/total number of cases], compared with 54.4% for the middle cerebral artery and 65.5% for the umbilical artery. The results were more encouraging for prediction of adverse perinatal outcome; diagnostic accuracy for the cerebral-umbilical ratio was 90%, compared with 78.8% for the middle cerebral artery and 83.3% for the umbilical artery.

Blood Flow Velocity↗
PubMed1988

[Biopsy of the chorionic villi in the early diagnosis of chromosomal diseases].

In the first trimester of pregnancy two simple chorionic villus sampling method, carried out under ultrasound guidance, with transabdominal or transcervical aspiration, was evaluated in 257 cases at risk for chromosomic diseases. The high efficacy of the transabdominal aspiration was demonstrated by obtain villus tissue for karyotyping in all but one case. In only one sample the abnormalities detected were not confirmed (one case of false positive).

Chorionic Villi Sampling↗
PubMedDate not supplied

[Resectoscopic endometrial ablation in the treatment of recurrent, dysfunctional menometrorrhagia: our experience].

UNLABELLED: Advances in hysteroscopic surgery provide additional options to hysterectomy for the treatment of dysfunctional uterine bleeding resistant to medical therapy and multiple curettages. Two techniques are now available: (a) Resectoscopic endometrial ablation. (b) Electrocoagulation or laser photovaporisation of endometrium. 52 patients underwent resectoscopic endometrial ablation at the Gynaecology Department of Parma University from January 1991 to April 1993. All patients suffered from dysfunctional uterine bleeding without atypical histologic findings on endometrial biopsies and had a normal shaped uterine cavity. 41 patients were subsequently contacted for follow-up. Follow-up period ranged from a minimum of 3 months to a maximum of 24 months. 78.1% of the patients reported a satisfactory outcome (amenorrhea or decreased menstrual flow). No operative complication occurred. Post operative complications included one case of hematometra. CONCLUSIONS: resectoscopic endometrial ablation is an advantageous technique but our follow-up period is relatively short and long term sequelae have yet to be determined.

Adult↗