Temporal deterioration of wavelength discrimination with successive comparison method

The wavelength discrimination threshold (Δλ) was measured with a successive comparison method, in which two stimuli of different wavelengths were presented in the left and right half of 2.2° or 2.7° bipartite field, respectively, with a certain stimulus onset asynchrony (SOA). The stimulus duration was kept constant at 110 msec. The Δλ value for five different wavelengths, 430, 470, 520, 570 and 610 nm, was found to be constant up to SOA= 60 msec and increased gradually till SOA= 190 msec. The wavelength discrimination functions with SOA of 0 and 550 msec were also obtained for 430 through 650 nm in 10 nm steps. At all wavelengths the values with SOA of 550 msec were about twice as large as those with SOA of 0 msec. The present results indicate that the wavelength discrimination deterioration is complete within a relatively short period of time.     

Purity discrimination: Successive vs simultaneous comparison method

Purity discrimination thresholds (Δp) were measured with successive (SOA = 3 sec) and simultaneous (SOA = 0 sec) comparison methods for seven dominant wavelengths: 410, 480, 500, 530, 570, 600 and 650 nm. The stimulus duration was 1 sec. The Δp values with the successive comparison method were found to he about 1.5–2.0 times larger than those obtained in the simultaneous case. The degree of purity discrimination deterioration shown in this study is similar to that of wavelength discrimination deterioration previously reported (Uchikawa and Ikeda, 1981, Vision Res.21, 591–595). Saturation shifts of stimuli with the successive comparison method were also observed: these were toward increased saturation direction for most dominant wavelengths.     

Gamete development inPlasmodium berghei regulated by ionic exchange mechanisms

Ionic regulation in the induction of exflagellation ofPlasmodium berghei was investigated by culturing the parasites in various isotonic media. Of the salts tested, NaHCO₃ exhibited the highest activity in inducing exflagellation, whereas KHCO₃ showed no activity. In the absence of HCO ₃ ^– , media containing monovalent cation (Na⁺, K⁺, Cs⁺, Rd⁺, choline⁺, lysine⁺, arginine⁺) and Cl^– also induced exflagellation, but their activities were lower than that of NaHCO₃. Anions of Br^– or NO ₃ ^– could be substituted with Cl^–, whereas other anions such as I^–, NO ₂ ^– , SO ₄ ^2– , SCN^–, H₂PO ₄ ^– , or HPO ₄ ^2– failed to induce exflagellation, as did tetramethylammonium-Cl, CaCl₂, MgSO₄, MgCl₂ and sucrose as well. These results suggest that the induction of exflagellation requires the presence of Na⁺ and HCO ₃ ^– or monovalent, membrane-permeable cation and Cl^– in the medium. Measurements of the efflux of H[¹⁴C]O ₃ ^– or Cl^– indicated that these anions were released from the cells into the NaCl or the NaHCO₃ medium, respectively, probably by exchange in HCO ₃ ^– /Cl^–. Determination of intracellular ionic concentrations by electron microscopic X-ray microanalysis of cryopreserved specimens revealed that in the NaHCO₃ medium, external Na⁺ (and probably HCO ₃ ^– ) enters the gametocytes by exchange with internal Cl^– (and probably H⁺), whereas in Cl^–-containing media, external unspecified cation and Cl^– influx by exchange, probably with H⁺ and HCO ₃ ^– . It is therefore suggested that two separate ion exchangers, i.e., Na⁺-dependent HCO ₃ ^– (in)/Cl^–(out) and nonspecific monovalent-cation-dependent Cl^–(in)/HCO ₃ ^– (out) exchangers, are involved in the induction of gametogenesis inP. berghei. Furthermore, the presence of both classes of anion in the medium enhanced exflagellation activity and increased Na⁺ uptake more than did the NaCl or NaHCO₃ medium alone. The apparent synergistic enhancement by two contraactive anion exchangers is consistent with a recycling model of pH_i regulation, in which HCO ₃ ^– and Cl^– are exchanged between the cells and the media, resulting in the acceleration of monovalent cation/H⁺ exchange.This work was supported by a Grant-in-Aid (No. 01570212) from the Ministry of Education, Science and Culture, Japan and the Ohyama Health Foundation, Japan (to FK), and in part by the Medical Research Council, United Kingdom (to RES)     

Stimulatory effect of ipriflavone on formation of bone-like tissue in rat bone marrow stromal cell culture

The effects of ipriflavone (IP) (10^–5 M) on bone formation were studied in stromal cells from the femoral bone marrow of young adult rats cultured for 21 days in the presence of -glycerophosphate and dexamethasone. Stereoscopic microscopy showed nodule formation after 14 days of culturing, and both the number and the size of the nodules increased with time. The alizarin-red-stained calcified area in the nodules in the IP group was nearly 4 times as large as that in the control after 21 days. Light and electron microscopy revealed the presence of many osteoblast-like cells with developed rough endoplasmic reticulum and Golgi apparatus in the nodules in the control group after 14 days, and a collagenous fibril network was seen among the cells. After 21 days, calcification of the dense collagenous fibril network and bone matrix-like tissue were observed in many nodules, resulting in the formation of bone-like tissue containing osteocyte-like cells. In the IP group, the collagenous fibril network area in the nodules was greater than that in the control after 14 days, and a further increase in both the dense collagenous fibril network area and calcified bone-like tissue area was observed after 21 days. These findings indicate that IP stimulates bone-like tissue formation in the rat bone marrow stromal cell culture, suggesting that the promotion of collagen production by osteoblasts is involved in the stimulation of bone-like tissue formation by IP.     

The latest innovations in the operation of en-bloc resection on the frontal skull base

We have organized skull base surgery teams with otolaryngologists, neurosurgeons and plastic surgeons since 1993 and managed frontal skull base malignancies by a combined transbasal and transfacial approach. However, in the maneuvers, several problems are yet to be solved in minimizing tumor recurrence and postoperative complications. We have recently developed a microscopic en-bloc resection method assisted by an endoscope, and VFOT flap (vascularized frontal outer table flap) for the reconstruction on the frontal skull base. The VFOT flap can be elevated simultaneously with bifrontal craniotomy. The pedicled calvarian bone is split, and the frontal outer table with the pericranium is placed on the frontal base defect caused by the tumor resections. Those procedures seem to be useful for skull base surgery, and easy to perform for neurosurgeons.     

Subjective and functional results after total gastrectomy: prospective study for longterm comparison of reconstruction procedures

Background: Many reconstruction procedures have been developed in efforts to resolve patients' complaints after total gastrectomy. However, there have been few reports of longterm comparisons between reconstruction procedures, especially with regard to the prevention of duodenal food passage. This study was undertaken to compare the longterm subjective and functional results among Roux-en-Y esophagojejunostomy (R-Y), R-Y with pouch (P-Y), and jejunal interposition with pouch (P-I) after total gastrectomy. Methods: Consecutive patients requiring curative total gastrectomy were enrolled in this prospective study by the envelope method. Results: Hospital stay was longer following a P-I than an R-Y or a P-Y. Over 50% of R-Y patients complained of heartburn, and 20% of R-Y patients showed dumping syndrome throughout the postoperative period, with this rate being significantly different from rates in the other two groups. P-Y patients complained of early satiety in the late postoperative period, while P-I patients complained of early satiety in the early postoperative period. The nutritional index in P-I patients was higher than those in patients with the other two procedures. Gastrointestinal and hepatobiliary dual scintigraphy (GHDS) showed that the rate of bile reflux with an R-Y was relatively high after surgery. Food reflux with a P-Y was increased (9.4% to 11.1%), but with a P-I food reflux was decreased at 3 years after surgery (13.3% to 9.9%). Patients with a P-Y had a faster recovery of body, weight in the early postoperative period; however, at 5 years after operation, body weight recovery with a P-I was greatest. Conclusion: Reconstruction should be performed with pouch formation after total gastrectomy with curative intent. Received: March 7, 2002 / Accepted: September 26, 2002 Acknowledgments This study was partly supported by the University of Tsukuba Research Project. Offprint requests to: S. Adachi     

Seasonal changes in calcium homeostasis affect the incidence of postoperative tetany in patients with Graves' disease

BACKGROUND: We have found that postoperative tetany occurs in patients with Graves' disease who have secondary hyperparathyroidism caused by a deficiency in calcium and vitamin D concomitant with transient hypoparathyroidism after surgery. There are seasonal variations in serum 25-hydroxyvitamin D (25[OH]D) concentrations. The purpose of this study was to investigate the effects of seasonal changes in calcium homeostasis on the incidence of postoperative tetany in patients with Graves' disease who undergo subtotal thyroidectomy. PATIENTS AND METHODS: A prospective study was carried out to investigate sequential changes in serum levels of intact parathyroid hormone (iPTH), calcium and other electrolytes, 25(OH)D, and 1,25-dihydroxyvitamin D (1,25[OH]2D) in female patients with Graves' disease who underwent subtotal thyroidectomy during the summer (n = 89) and during the winter (n = 89). RESULTS: The serum levels of calcium, magnesium, and 25(OH)D were significantly higher, but iPTH levels and 1,25(OH)2D levels were lower in summer than in winter. The percentage of vitamin D deficiency (25(OH)D < 25 nmol/L) was 23% in summer and 62% in winter (P < .001). iPTH was below the detection limit on the first postoperative day in 15 patients (13.8%) in summer and in 13 patients (11.4%) in winter. In summery, tetany developed in only 4 of 15 patients and in one patient whose iPTH level was below normal (incidence of tetany, 5.6%). In winter, however, tetany developed in 6 of 13 patients and in 4 patients whose iPTH level was below normal (incidence of tetany, 11.2%). CONCLUSIONS: Patients with Graves' disease are more susceptible to calcium and vitamin D deficiency during the winter than during the summer, resulting in the tendency toward a higher incidence of postoperative tetany in winter.     

Alteration of p53 Clonality Accompanying Colorectal Cancer Progression

The aim of this study was to clarify whether or not the status of gene alteration is heterogeneous in intramucosal carcinoma and homogeneous within invasive carcinoma. We selected 10 colorectal carcinoma cases (1 mucosal, 5 submucosal and 4 advanced carcinomas including 2 cases with lymph node metastasis) and analyzed the p53 gene sequence. Six colorectal cancers in this study showed heterogeneity in p53 mutations in cells from the intramucosal part. In the invasive part of a carcinoma, p53 mutation status was homogeneous intratumorally in all cases. These data indicate that, in regard to p53 gene alterations, colorectal cancers can be composed of various subclones when limited to the mucosa, but clonal selection occurs when one of these subclones commences invasion to the submucosa, generating a monoclonal invasive carcinoma.