Biomedical subjects

B Nikolov

Publications and source records attributed to B Nikolov.

16 recordsLinked to original sources

PubMed1999

Porcine granulosa cells produce a progesterone secretion inhibitory activity.

OBJECTIVE: To extend our previous observations of granulosa cell conditioned medium inhibition on basal and FSH-stimulated progesterone secretion by granulosa cells from large porcine antral follicles. METHODS: Granulosa cell conditioned media (SGCCM) were obtained from cultures of granulosa cells which were harvested from small porcine antral follicles. SGCCM were fractionated by filtration through an Amicon XM-50 and an PM-10 membrane. RESULTS: Two fractions - XM-50 filtrate (<50 kDa) and PM-10 retentate (10-50 kDa) - exhibited well expressed inhibitory effect on the progesterone secretion from large follicle granulosa cells in vitro. Such inhibitory effect was fully prevented by heat treatment, partially inactivated by trypsin digestion (P<0.05), but was resistant to several freeze-thaw cycles and storage at -20 or -70 degrees C for up to one year. CONCLUSIONS: It is suggested that SGCCM contains some regulatory substance(s) capable of inhibiting progesterone secretion by cultured granulosa cells and that the molecular weight of such substance is presumably between 10-50 kDa.

Animals↗

PubMed1998

Vagus nerve stimulation for symptomatic generalized epilepsy: a pilot study.

PURPOSE: Patients with symptomatic generalized epilepsy (SGE) may have antiepileptic drug (AED)-resistant mixed generalized seizures. Vagus nerve stimulation (VNS) reduces partial seizures and may help SGE. METHODS: We added VNS to stable AED therapy in five SGE patients. Nine-month postoperative VNS treatment seizure rates were compared to a 1-month preoperative baseline. RESULTS: All patients had mixed generalized seizures, EEG generalized slow spike-and-wave and behavioral abnormalities. Median number of previous AEDs taken was 6 (range 5-12). Median baseline seizure rate was 75/month (range 29-110). VNS produced a median seizure rate production of -41% (range -40% - -85%). Adverse events reported in one patient each were: incisional infection, choking sensation and voice change; and coughing (noted by two patients). One patient discontinued VNS due to coughing. CONCLUSIONS: We conclude that VNS may be useful add-on therapy for SGE. A larger, controlled, and blinded trial may be warranted.

Adult↗

PubMed1994

Changes in pancreatic islets in aging Wistar and Zucker rats: a histochemical and ultrastructural morphometric study.

Morphometrical and cytochemical techniques have been applied to characterize the islets of Langerhans tissue in lean and obese Zucker fa/fa and Wistar rats. The changes in cytologic composition correlated with levels of serum glucose and lipids in obese rats and progressed significantly with increasing body weight. Histochemical and enzyme abnormalities observed in Zucker fa/fa and Wistar rats reflect the degenerative and reactive processes in the pancreas: a decrease in Krebs cycle and pentose pathway and increased lysosomal acid phosphatase reflect the degeneration of the islets. Changes consisted of pronounced insulin cell hyperplasia and disruption of islet architecture. The raised functional activity in the islet B-cells of the Zucker fa/fa and Wistar rats was reflected in enlargement and fragmentation of the Golgi apparatus. An increased proportion of light granules is associated with increased insulin secretion, which reinforces the idea that light granules are responsible for immediate insulin secretion, whereas the dark granules represent the insulin stored in the cell for a longer period The islets of Langerhans of the Zucker fa/fa and Wistar rats show marked differences in morphological, histochemical and morphometrical characteristics when compared with littermates. There is a marked difference in insulin secretion between the obese Zucker fa/fa and Wistar rats and its non-obese littermate. These differences may be related to the development with obesity of aging and genetically-conditioned animals.

Aging↗

PubMed1994