Transition from stochastic to deterministic behavior in calcium oscillations

Simulation and modeling is becoming more and more important when studying complex biochemical systems. Most often, ordinary differential equations are employed for this purpose. However, these are only applicable when the numbers of participating molecules in the biochemical systems are large enough to be treated as concentrations. For smaller systems, stochastic simulations on discrete particle basis are more accurate. Unfortunately, there are no general rules for determining which method should be employed for exactly which problem to get the most realistic result. Therefore, we study the transition from stochastic to deterministic behavior in a widely studied system, namely the signal transduction via calcium, especially calcium oscillations. We observe that the transition occurs within a range of particle numbers, which roughly corresponds to the number of receptors and channels in the cell, and depends heavily on the attractive properties of the phase space of the respective systems dynamics. We conclude that the attractive properties of a system, expressed, e.g., by the divergence of the system, are a good measure for determining which simulation algorithm is appropriate in terms of speed and realism

A MALIGNANT LESION OF THE VULVA – A RARE CASE IN A 22-YEAR-OLD WOMAN

Background: Malignant lesions on the vulva are very rare in young women. Inspite of all the development in modern medicine their origin sometimes remains undiscovered and their development cannot be explained. Patients and methods: We describe a case of a 22-year-old woman, who was initially treated for what was believed to be an atheroma of the vulva. A biopsy was performed. The histology revealed a malignant metastatic lesion. Extensive diagnostic procedures were performed (gynecologic ultrasound, ultrasound of the abdomen, CT, MR, PET CT) and foreign specialists in gynecologic pathol- ogy were consulted. Conclusions: Although extensive diagnostic procedures were performed the origin of the malignant change causing the described lesion remained a mistery

SERTOLI-LEYDIG CELL TUMOR; A RARE CASE IN A POSTMENOPAUSAL PATIENT – CASE REPORT

Background. Sertoli-Leydig cell tumors belong to the group of sex cord stromal tumors of the ovary. They account for less than 0.5 % of all ovarian tumors and occur primarily in young women between 20 and 30 years of age. This type of tumors can secrete androgens, causing virilisation, and are extremely rarely presented in postmenopausis. Methods. A 73-year old multiparous woman was presented to our institution with complaints of abdominal distention and abdominal pain in her lower abdomen. On physical examination, she had a large, fixed palpable abdominal mass, approximately 20 cm in diameter, arising from the pelvis. The laboratoric tests revealed an elevated level of CA125 of 221.3 U/ml of serum. The ultrasound showed a complex cystic and solid pelvic tumor. There was no sign of ascites. Her hormonal status was within normal range and she also showed no signs of virilisation. On laparotomy a complex left ovarian mass, measuring 30 × 27 × 15 cm was found and sent to frozen section. The result of frozen section was a malignant tumor of unknown origin, therefore a radical surgical procedure was performed. The histopathological examination established the diagnosis of a malignant Sertoli-Leydig cell tumor of the left ovary, of intermediate differentiation. Other removed tissue was free of malignant cells. The early postoperative course was uneventful and the patient was released from hospital 10 days after surgery. However, she returned to our institution 16 days after surgery due to a proximal thrombosis of v. saphena magna. The patient was treated with low-molecularweight heparin and later warfarin for 6 weeks post operation. 16 months after the operation she was symptomatically treated for severe microcytic anemia. She showed no signs of a relapse. 27 months after primary surgery she was operated for the second time due to acute bowel obstruction. She had large masses of necrotic tumor removed from abdomen and transversostomia was performed. It was found to be a relapse of the malignant Sertoli-Leydig tumor, infiltrating the small intestines; the level of serum CA 125 also showed an increase. Conclusions. We describe a case of a Sertoli-Leydig cell tumor in a postmenopausal woman, treated in our institution