The adaptor protein Shc contains a phosphotyrosine binding (PTB) domain and a Src homology 2 (SH2) domain, both of which are known to interact with phosphorylated tyrosines. We have shown previously that tyrosine 1148 of the activated epidermal growth factor (EGF) receptor is a major binding site for Shc while tyrosine 1173 is a secondary binding site in intact cells. In the present study, we investigated the interaction between the PTB and SH2 domains of Shc and the activated human EGF receptor. Mutant 52-kDa Shc with an arginine-to-lysine substitution at residue 175 in the PTB domain (Shc R175K) or 397 in the SH2 domain (Shc R397K) was coexpressed in Chinese hamster ovary cells overexpressing the wild-type or mutant EGF receptors that retained only one of the autophosphorylation sites at tyrosine 1148 (QM1148) or 1173 (QM1173). Shc R397K was coprecipitated with the QM1148 and QM1173 receptors, was tyrosine-phosphorylated, and associated with Grb2 and Sos. In contrast, coprecipitation of Shc R175K with the mutant receptors was barely detectable. In cells expressing the QM1173 receptor, Shc R175K was tyrosine-phosphorylated and associated with Grb2, while association of Sos was barely detectable. In cells expressing the QM1148 receptor, tyrosine phosphorylation of Shc R175K was markedly reduced. When both Shc R175K and 46-kDa Shc R397K were coexpressed with the mutant receptors, p46 Shc R397K was dominantly tyrosine-phosphorylated. In cells expressing the wild-type receptor, Shc R397K, but not Shc R175K, translocated to the membrane in an EGF-dependent manner. In addition, Ras activity stimulated by the immunoprecipitates of Shc R397K was significantly higher than that by the immunoprecipitates of Shc R175K. The present results indicate that tyrosine 1148 of the activated EGF receptor mainly interacts with the Shc PTB domain in intact cells. Tyrosine 1173 interacts with both the PTB and SH2 domains, although the interaction with the PTB domain is dominant. In addition, Shc bound to the activated EGF receptor via the PTB domain dominantly interacts with Grb2-Sos complex and plays a major role in the Ras-signaling pathway.

To evaluate the role of cobalamin (Cbl) on spermatogenesis, the effect of dietary vitamin B(12) deficiency on early spermatogenesis was histologically investigated in male fetuses and newborns in the first filial generation (F(1) males) of rats. There was no difference in the number of gonocytes and supporting cells of Sertoli in the gonad in male fetuses on day 16 of gestation and in the testes in F(1) males at 0 days of age between vitamin B(12)-deficient (VB12-D) and vitamin B(12)-supplemented (VB12-S) groups. However, at 21 days of age, a decreased number of spermatogonia and no spermatocytes were observed in the VB12-D group. Numerous TUNEL positive cells were located among spermatocytes of the spermatogenic epithelium. The ultrastructural features examined using transmission electron microscopy were considered to be indicative of apoptosis. The incidence of seminiferous tubules having apoptotic cells was 51.5% in the VB12-D group. At 60 days of age, aplasia of the spermatids and spermatozoa was detected in the VB12-D group. In the connective tissue between the seminiferous tubules, many interstitial Leydig cells and blood vessels were observed in the VB12-D group, as compared with the VB12-S group. These changes produced by vitamin B(12) deficiency can be reversed by providing a VB12-S diet after weaning at 21 days of age. From these findings, such a vitamin B(12) deficiency during gestation and lactation could affect the germ cells and especially damage spermatocytes in F(1) male rats, which indicates that Cbl may be an essential constituent in the meiosis of spermatogenesis.

Objective: A binary grading system has been proposed to assess the amount of solid growth, the pattern of invasion, and the presence of necrosis, and thereby divide endometrial endometrioid carcinomas into low- and high-grade tumors. We analyzed this system for predicting the prognosis, with respect to inter- and intraobserver reproducibility and treatment modalities. Methods: A total of 200 endometrial carcinomas, based on hysterectomy specimens, were graded according to the binary grading system, for comparison against The International Federation of Gynecology and Obstetrics (FIGO) system and nuclear grading. Results: Both inter- and intraobserver agreement using the binary grading system (ĸ = 0.57; percent agreement: 82% and ĸ = 0.62; 84%) were superior compared with the FIGO system (0.50; 60% and 0.62; 73%) and the nuclear grading (0.23; 49% and 0.43; 65%). Patients with early-stage low-grade tumors had a 98% rate for 5-year survival (5YS). Patients with early-stage high-grade tumors, and those with advanced-stage low-grade tumors, had respectively 86% to 87% rates for 5YS. But patients with advanced-stage high-grade tumors had a 49% rate for 5YS. In binary low-grade early-stage tumors, the patient outcome was better with no adjuvant therapy and chemotherapy, compared with other therapies. Conclusion: A binary grading system was superior to others in permitting greater reproducibility and predicting the prognosis of endometrial cancer patients.

A rare case of Castleman's disease with myasthenia gravis is reported. A 55-year-old woman with bilateral ptosis, speech impairment, and severe dyspnea had been previously diagnosed with myasthenia gravis. Computed tomography showed a 5 cm × 3 cm paratracheal mass in the mediastinum, thought to be an ectopic thymoma. Two days after surgical resection, the patient suddenly developed dyspnea. Postoperative myasthenic crisis was diagnosed, and plasmapheresis was performed. Her general condition improved, and her subsequent course was uneventful. The final pathological diagnosis was mediastinal solitary Castleman's disease, hyaline vascular type. Castleman's disease with myasthenia gravis is especially rare. One of the serious complications is postoperative myasthenic crisis. For patients with myasthenia gravis, the rate of postoperative myasthenic crisis seems significantly higher in Castleman's disease patients than in patients with thymic epithelial tumors. Castleman's disease with myasthenia gravis is discussed along with a review of the literature.