High voltage pulse shaping of e-beam diode using perveance variation.

This paper presents a new high voltage pulse shaping methodology for pulsed power applications. The aim is to generate high voltage square pulse across anode cathode gap of e-beam diodes. The non-linear time varying perveance characteristics of e-beam diodes are used for shaping of output voltage pulse across it, generated directly from Marx generator. Analytically, it has been shown in the paper that under certain conditions, if achieved, Marx generator feeding an e-beam diode can produce a square-like pulse at the output, without any extra pulse shaping arrangements. Experimental results to support the analysis are also presented in the paper.

Prognostic factors and rational approach in the treatment of submucosal cancer of the stomach.

In early gastric cancer, lymph node metastasis is known to be a prognostic factor. A retrospective study of 134 patients with submucosal gastric cancer (SMGC) who had undergone gastrectomy with lymph node dissection was performed to evaluate the prognostic factors and indication of postoperative chemotherapy. Five-year disease-free survival rate for 121 patients without nodal metastasis was 100% with (n = 62) or without postoperative chemotherapy (n = 59). On the other hand, it was 72.9% for 13 patients with nodal metastases, although all patients had undergone D2 or D3 resection and received postoperative chemotherapy. Tumor recurrence occurred only in three patients (n = 3) with alpha-fetoprotein (AFP) producing cancer and lymph node metastasis. Multivariate analysis with the Cox's proportional hazard model revealed AFP positivity to be a new independent prognostic factor in addition to lymph node metastasis in the patients with SMGC. Our findings suggest that routine use of postoperative chemotherapy does not appear rational for the patients without nodal metastasis and that new modalities of operation and chemotherapy may be necessary for the patients with AFP producing SMGC with nodal metastasis. The necessity of chemotherapy in conventional-type SMGCs with nodal involvement remains to be studied in future.

Comparison between the clinicopathologic features of AFP-positive and AFP-negative gastric cancers.

We compared 27 cases of alpha-fetoprotein (AFP)-positive gastric cancer with 478 cases of AFP-negative gastric cancer in our department. The incidences of AFP-positive gastric cancer were 5.4% (27/505), 7.2% (23/218), and 2.1% (4/187) for overall, advanced, and early cases of gastric cancer, respectively. Sex, age distribution, pathologic type, and serum carcinoembryonic antigen levels were similar between these two groups. Borrmann III type cancer, lymph node metastasis, lymphatic and venous microinvasion of the gastric wall, and incidence of synchronous and metachronous liver metastasis occurred more often in the AFP-positive group. It was suspected that the character of early venous invasion contributed to the high incidence of liver metastasis. Liver metastasis occurred in 72% of AFP-positive patients, all of whom died within 2 yr. Long-term survival of the AFP-positive group was worse than that of the negative group. The 1-, 3-, 5-, and 7-yr survival rates of both groups were 38.7%, 11.6%, 11.6%, 11.6%, and 71.3%, 57.8%, 52.8%, 49.6%, respectively (p less than 0.001).

alpha Fetoprotein producing early gastric cancer with liver metastasis: report of three cases.

Three cases of alpha fetoprotein producing early gastric cancer are presented. Liver metastases occurred in all patients shortly after curative gastrectomy and all died within two years. The incidence of liver metastasis was significantly higher than that in alpha fetoprotein negative early gastric carcinoma (p less than 0.001). The incidences of lymph node metastasis and invasion in lymph vessels and veins were also substantially higher in this group of patients. Two radical hepatic resections, including extended right lobectomy, were performed on one patient but the tumour recurred immediately.

Insulin resistance in polycystic ovary syndrome.

Patients with polycystic ovary syndrome (PCO) who are obese and exhibit acanthosis nigricans have been reported to have insulin resistance. We studied 21 euglycemic, euprolactinemic patients with PCO without acanthosis nigricans. Eleven of these patients were hirsute and the remaining 10 were not. Eight women with chronic anovulation, who were weight matched with the PCO patients, were studied along with the 11 ovulatory control subjects. Compared to control subjects, women with chronic anovulation had similar levels of immunoreactive luteinizing hormone (LH), bioactive LH, 17 beta-estradiol, testosterone (T), and dehydroepiandrosterone sulfate but significantly higher fasting immunoreactive insulin levels (p less than 0.05). The nonhirsute patients with PCO had higher immunoreactive insulin levels compared to patients with chronic anovulation and control subjects (p less than 0.05) while hirsute patients with PCO had higher immunoreactive insulin levels than nonhirsute ones (p less than 0.05). There was a significant positive correlation between fasting immunoreactive insulin levels and serum T. Fasting immunoreactive insulin also showed a significant correlation with serum LH and bioactive LH. After receiving 100 gm of oral glucose, hirsute patients with PCO had significantly higher insulin responses compared to those of control subjects despite similar glucose responses. Red blood cell insulin-binding sites and receptor affinities were similar in hirsute patients and control subjects. These data suggest that the hyperinsulinemia of patients with PCO may be related, in part, to the elevated LH and androgen levels and may be a postreceptor defect.