Biomedical subjects

K Yazawa

Publications and source records attributed to K Yazawa.

212 records · Page 12Linked to original sources

PubMedDate not supplied

Turbidometric characterization of the postantifungal effect: comparative studies with amphotericin B, 5-fluorocytosine and miconazole on Candida albicans.

The phenomenon of persistent suppression of Candida albicans yeast cell growth after short drug exposures (postantifungal effect, PAFE) was determined by performing comparative studies using different concentrations of 5-fluorocytosine (5-FC), amphotericin B (AMPH) and miconazole (MCZ). An in vitro turbidometric method was used to measure cell growth and to quantitate the PAFE after removal of the drug by dilution following exposure to C. albicans yeast cells for 0.5 h, 1 h or 2 h. The PAFE was determined by the difference in time (h) required for growth of the control and test cultures to increase to the 0.5 absorbance level following removal of the antifungal agent. A PAFE was demonstrated with each agent and generally the length of the PAFE was dependent upon the concentration of the drug and the time of exposure. An exposure time of 0.5 h resulted in PAFEs ranging from 0.6 to 16.7 h with 5-FC, 0 to 16.5 h with AMPH and 0.1 to 14.1 h with MCZ. In most instances exposure of the cells to each drug for 1 or 2 h resulted in slightly longer PAFEs, respectively. Longer PAFEs were induced with lower concentrations of 5-FC as compared to AMPH and MCZ. The data from such PAFE assays may be useful for determining in vivo treatment regimens, since longer PAFEs may allow for intermittent dosing instead of continuous drug administration.

Amphotericin B↗

PubMedDate not supplied

In vitro comparative evaluations of the postantifungal effect: synergistic interaction between flucytosine and fluconazole against Candida albicans.

In vitro comparative evaluations were performed to study the efficacy of combinations of flucytosine and fluconazole in producing a postantifungal effect (PAFE) on Candida albicans. Initial studies were done to determine MIC, FIC (fractional inhibitory concentration) and optimal PAFE parameters. A turbidometric method was used to measure yeast cell growth following exposure to different concentrations of the two drugs for periods of 0.5, 1 or 2 h at temperatures of 30 degrees C and 37 degrees C. The PAFE was determined by the difference in time (h) required for growth of the control and test cultures to reach the 0.5 absorbance level following removal of the drug by dilution. Ten strains of C. albicans were then assayed (30 degrees C; 2 h exposure time) and a synergistic PAFE was evidenced with the two drugs at concentrations well below their individual MICs. PAFEs ranging from 3.8 to 10.5 h, which persisted for 1.2-2.5 h longer than those achieved with either agent separately, were evidenced when flucytosine and fluconazole were combined (flucytosine: fluconazole ratios of 1:16-1:32) at concentrations ranging from 0.024 to 0.098 micrograms ml-1 and 0.78 to 1.56 micrograms ml-1 respectively. The concentrations of each agent required to produce an optimal PAFE varied according to the C. albicans strain being assayed.

Candida albicans↗

PubMedDate not supplied

Synergistic interaction of miconazole and fluconazole at sub-MIC level on Candida albicans.

The in vitro combination effect of two azole antimycotics, miconazole and fluconazole, against Candida albicans was studied. When minimum (MIC) and sub-minimum (sub-MIC) inhibitory concentration and fractional inhibitory concentration (FIC) determinations were made, a synergistic interaction of the two agents at the concentration well below their individual MICs (at sub-MIC levels) was evidenced. The FIC index values ranged from 0.3 to 1.0 and the synergy was characterized by the potentiation of fluconazole activity with miconazole. The synergistic effect was also confirmed by a turbidometric method. On the other hand, such a synergistic effect against Candida krusei was not confirmed.

Candida albicans↗

PubMedDate not supplied

Comparison of in vitro antifungal activity of itraconazole and hydroxy-itraconazole by colorimetric MTT assay.

The in vitro antifungal activities of itraconazole and its active hydroxyl metabolite, hydroxy-itraconazole (R 63372), against Aspergillus fumigatus, Candida albicans and Cryptococcus neoformans were compared by visual assessment of growth as well as by colorimetric MTT [3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide] assay using microtitre plates containing four different media. Minimum inhibitory concentration (MIC) end points determined by the colorimetric MTT assay correlated well with those obtained by visual assay. The two drugs showed different MIC values depending on the medium used. The activity of itraconazole was equal to or greater than the activity of hydroxy-itraconazole against most of the fungi tested. Both drugs showed lower MIC values against A. fumigatus and Cr. neoformans in brain heart infusion broth (BHI) medium than in yeast nitrogen base (YNBG) medium, Sabouraud glucose broth (SAB) or "synthetic amino acid medium, fungal" (SAAMF). However, the MIC end point of these drugs against C. albicans in BHI and SAB media was difficult to determine visually as well as by MTT assay. In C. albicans, the MTT assay method using SAAMF and YNBG media is recommended for the determination of MICs.

Antifungal Agents↗

PubMedDate not supplied

In vitro antifungal activity of the new triazole D0870 against Penicillium marneffei compared with that of amphotericin B, fluconazole, itraconazole, miconazole and flucytosine.

The in vitro activity of D0870, a new triazole, was compared with that of fluconazole, itraconazole, miconazole, amphotericin B and flucytosine against recent clinical isolates of Penicillium marneffei in Thailand. The minimum inhibitory concentrations (MIC) values were determined by a microbroth dilution method using morpholinopropanesulphonic acid (MOPS)-buffered RPMI-1640 and brain heart infusion (BHI) medium. Yeast nitrogen base (YNB) medium with glucose was also used for the assay of flucytosine. D0870 was less active against P. marneffei than itraconazole, but its activity was similar to that of miconazole, superior to that of amphotericin B and markedly superior to that of fluconazole and flucytosine. Much lower MIC values of D0870 were observed with BHI medium.

Amphotericin B↗

PubMedDate not supplied

Postoperative exotropia.

One hundred fifty-four cases of infantile esotropia and acquired esotropia surgically treated before the age of seven were followed for a minimum of five years. We found 44% of infantile esotropia and 60% of acquired esotropia were converted to phoria with 20% having postoperative exotropia. Eight to 10 years of age seemed to be the turning point from esotropia to exotropia. Spontaneous decrease of accommodative convergence with age seemed to be the most important causative factor in relation to secondary exotropia. Long-term follow-up revealed the residual angle of deviation decreased with time and undercorrected esotropia resolved spontaneously. Therefore, it is the responsibility of the surgeon to encourage his patients to return regularly for follow-up visits even ten years after surgery for possible spontaneous change of deviation.

Adolescent↗

PubMedDate not supplied

A case of Zollinger-Ellison syndrome produced by gastrinoma in the duodenum accompanied with multiple endocrine neoplasia type 1.

A case of Zollinger-Ellison syndrome produced by gastrinoma in the duodenum accompanied by multiple endocrine neoplasia type-1 (MEN-1) is reported. A 46 year-old female underwent distal gastrectomy due to gastric ulcer 5 years ago. As ulceration of the residual stomach recurred, further examination was performed. Hyperprolactinemia, hypergastrinemia, primary hyperparathyroidism, pancreatic tumor, and duodenal carcinoid were evident, and the diagnoses of Zollinger-Ellison syndrome and MEN-1 were established. The origin of the gastrin secretion was suspected to be from the pancreatic tumor, so sampling of the portal blood was performed. As lesion on the gastrinoma in the pancreas could not be identified, total parathyroidectomy was performed for primary hyperparathyroidism. The level of the gastrin secretion, however, remained high. Partial resection of the duodenum for the duodenal carcinoid and a distal pancreatectomy were carried out concurrently. Immunohistochemical study of the anti-gastrin antibody revealed duodenal tumor cells. Initially, the gastrinoma was thought to be in the pancreas, however, the lesion accompanied with MEN-1 and the Zollinger-Ellison syndrome had occurred in the duodenum.

Duodenal Neoplasms↗

PubMedDate not supplied

Basaloid squamous carcinoma of the esophagus with analysis by in situ nick end labeling and PCNA immunostaining.

BACKGROUND/AIMS: Basaloid squamous carcinoma (BSC) of the esophagus has been associated with poor outcome after surgery. In this study, apoptosis and cell proliferation of BSC were studied to evaluate the malignant potential of this cancer. METHODOLOGY: In tissue samples from 4 out of 5 BSC patients (1 patient with pre-operative radiotherapy was excluded) and from 30 patients with squamous cell carcinomas (SCCs) of the esophagus, apoptosis was studied by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end labeling (TUNEL), and cell proliferation was evaluated by the immunostaining of proliferating cell nuclear antigen (PCNA). Two of the 5 patients with BSC died of recurrence and the remaining 2 patients are alive without recurrence. RESULTS: TUNEL-positive cells and PCNA-positive cells were observed to exist randomly and independently in the BSC samples. In the well- and moderately differentiated SCCs, TUNEL-positive cells and PCNA-positive cells were locally observed. The apoptotic index was significantly lower in the BSC than in the SCC tissues, and the PCNA labeling index was significantly higher in BSC than in SCC. CONCLUSIONS: These results suggest that BSC of the esophagus has great proliferative activity and weak apoptosis. These characteristics may reflect the aggressive behavior and poor prognosis of esophageal BSC. Early detection of this tumor, as in the present 2 cases, will contribute to a better prognosis.

Aged↗

PubMedDate not supplied

Immunohistochemical expression of thymidine phosphorylase/platelet-derived endothelial cell growth factor in squamous cell carcinoma of the esophagus.

BACKGROUND/AIMS: Thymidine phosphorylase (dThdPase) is identical to platelet-derived endothelial cell growth factor which is an angiogenic factor. We attempted to clarify the significance of dThdPase expression in esophageal squamous cell carcinoma (SCC). METHODOLOGY: Tissues samples were taken from 50 patients with esophageal SCC after curative surgery. The expression of dThdPase was immunohistochemically examined using a monoclonal antibody to dThdPase (clone 654-1). Microvessels in SCC stained for Factor VIII-related antigen were counted. Vascular endothelial growth factor (VEGF) was immunostained with R11. Ki-67 antigen was immunostained with MIB-1, terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick end labeling was performed, and Ki-67 labeling index (LI) and apoptotic index were calculated. RESULTS: The expression of dThdPase was observed in 30 patients (60%). Between the SCC with and without dThdPase expression, significant differences were found in microvessel count (p < 0.001) and VEGF expression (p < 0.01), but not in Ki-67 LI and apoptotic index. With regard to the clinicopathologic factors, significant differences were observed in histologic venous invasion (p < 0.01) and lymph node metastasis (p < 0.05). Survival rate after surgery was better in the patients with dThdPase-negative SCC (p < 0.05), and distant organ metastasis after surgery was frequently observed in the patients with dThdPase-positive SCC (p < 0.05). CONCLUSIONS: These results suggest that dThdPase expression may be associated with angiogenic promotion and may be one of the prognostic factors in esophageal SCC.

Apoptosis↗

PubMedDate not supplied

Histochemical study of vascular endothelial growth factor in squamous cell carcinoma of the esophagus.

BACKGROUND/AIMS: Vascular endothelial growth factor (VEGF) plays a key role in tumor angiogenesis. The aim of this study was to clarify the significance of VEGF expression in esophageal squamous cell carcinoma (SCC). METHODOLOGY: Tissues samples were taken from 52 patients with esophageal SCC after surgery. VEGF expression in these SCCs was examined immunohistochemically. Microvessels in the tumor stained for Factor VIII-related antigen were counted. Ki-67 antigen as a proliferative marker was immunostained with MIB-1, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick end labeling was performed for the evaluation of apoptosis. Ki-67 labeling index (LI) and apoptotic index were then calculated. RESULTS: VEGF expression was observed in 30 of the patients (57.7%). The microvessel count was significantly higher (p = 0.007), and the apoptotic index was significantly lower (p < 0.0001) in the SCC with VEGF expression than in the SCC without it, but no significant difference was observed in the Ki-67 LI between these groups. There was an inverse correlation between the microvessel count and the apoptotic index (p = 0.007). In the clinicopathologic factors, histologic venous invasion of cancer cells (p = 0.039) and lymph node metastasis (p = 0.049) were significantly correlated with VEGF expression. The survival rate after curative surgery was better in the patients without VEGF expression (p < 0.05), and distant organ metastasis after surgery was frequently observed in the patients with VEGF expression (p = 0.023). CONCLUSIONS: These results suggest that VEGF expression is associated with angiogenesis in esophageal SCC, and may be a prognostic factor in patients with esophageal SCC. Furthermore, apoptosis may be influenced by angiogenesis in esophageal SCC.

Aged↗

PubMedDate not supplied

Risk factors associated with intra-operative blood loss in hepatectomized patients with giant cavernous hemangioma of the liver.

BACKGROUND/AIMS: The aim of this study was to clarify risk factors associated with intra-operative blood loss in hepatectomized patients with giant cavernous hemangioma (GCH) of the liver. METHODOLOGY: Twenty patients with GCH of the liver were treated by hepatectomy. Eleven patients with intra-operative blood loss > 2000 ml (mean: 7145 +/- 7080 m; Group 1) were reviewed retrospectively and compared to 9 patients with intra-operative hemorrhage < 2000 ml (mean: 918 +/- 429 ml; Group 2). RESULTS: Although there were no significant differences in pre-operative AST, ALT, and ICG-15 or fibrinogen and platelets between the two groups, pre-operative total bilirubin and fibrin degradation product (FDP) in Group 1 was significantly higher than in Group 2. Mean operation time and intra-operative blood transfusion in Group 1 versus Group 2 were 433 min vs. 213 min (p < 0.0001) and 3036 ml vs. 422 ml (p = 0.0072), respectively. The weight of resected liver (r = 0.821, p < 0.0001), maximum diameter of tumor (r = 0.782, p < 0.0001) and operation time (r = 0.748, p < 0.0001) were the most highly correlated with intra-operative blood loss, followed by pre-operative total bilirubin (r = 0.605, p = 0.0038), FDP level (r = 0.576, p = 0.0068) and intra-operative blood transfusion (r = 0.561, p = 0.0089). CONCLUSIONS: These findings suggest that pre-operative management to reduce the tumor size, total bilirubin and FDP levels may be essential to minimize intra-operative hemorrhage and blood transfusion.

Adult↗

PubMedDate not supplied

Effective treatment with chemotherapy and surgical resection for small cell carcinoma of the esophagus: report of a case.

We report on a patient with small cell carcinoma of the esophagus treated with effective combination chemotherapy followed by surgical resection. A 69 year-old male had an ulcerated tumor in the middle part of the esophagus, which was microscopically diagnosed as small cell carcinoma of the esophagus. After combination chemotherapy, endoscopy showed that the esophageal tumor had changed into a shallow ulcer. No cancer cell was found in the biopsy specimen of the ulcer. A subtotal esophagectomy with regional lymph node dissection was performed. Histological examination showed that a few cancer cells remained in a microvessel of the submucosal layer in the removed esophagus and no cancerous lesion was found in regional lymph nodes. The patient was well and was able to remain at home. However, he eventually died 21 months after first detection of the carcinoma due to progression of multiple lung and mediastinal lymph node metastases. After complete or partial remission is achieved by the combination chemotherapy, surgical resection may be recommended as the second therapy that occasionally produces long-term remission and possibly long-term survival for patients with small cell carcinoma of the esophagus, such as the present case.

Aged↗

PubMedDate not supplied

Development of a new transvenous patent ductus arteriosus occlusion technique using a shape memory polymer.

A novel percutaneous patent ductus arteriosus (PDA) occlusion technique, without the potential problems associated with conventional techniques, has been long awaited. The development of a novel transvenous PDA occlusion technique using a temperature-shape changeable occluder device, and the verification of its in vitro performance, were demonstrated in this study. The principles of this technique are: 1) the bar form device was inserted into the PDA transvenously by a guide wire and a pushing catheter, 2) the device was dashed with hot water through catheters, 3) the device was expanded by hot water in the PDA, and the PDA was occluded. The occluder device, made of a shape memory polymer (polynorbornene), was designed to have the monobloc configuration of a thin disk with a hole for a guide wire in the center and a cone. The barlike device by hot press was fully expanded within 10 sec upon immersion into 45 degrees C water. The mock-circulation test with the "great arteries" and a specially designed "PDA" showed 1) the introduction of hot water (45 degrees C) through the catheters caused expansion of the device which stayed in the "PDA" without any support, 2) the "aortic" pressure and the distal "aortic" flow increased rapidly, and the "pulmonary" flow reduced promptly. This resulted in a drastically reduced shunt ratio at the PDA from 68% to 30%. Thus, the novel PDA occlusion technique developed here functioned well to occlude the PDA in a great arteries model.

Cardiac Catheterization↗

PubMedDate not supplied

Two cases of gastric involvement of esophageal cancer: intramural metastasis and intramural lymph node metastasis.

Cases of esophageal cancer with intramural metastasis to the stomach and esophageal cancer with metastasis to an intramural lymph node of the stomach are herein reported. The former patient was a 52 year-old male. Squamous cell carcinoma (SCC) of the lower esophagus with an intramural metastasis located at the gastric cardia and a small leiomyoma at the fornix were resected. The latter patient was a 70 year-old female. SCC of the lower esophagus and an intramural lymph node metastasis located at the anterior wall of the gastric cardia were resected. The patient died nevertheless of multiple liver metastases. These gastric involvements were detectable by endoscopy before surgery. The clinicopathological features of these esophageal cancers were characterized; the sites were the lower part of the esophagus, and extreme lymphatic and vascular invasions were shown histologically. The gastric tumors were located in the upper third of the stomach, and the findings revealed submucosal tumors. It is therefore important to discriminate other gastric tumors, and to resect them simultaneously with esophageal cancer when a gastric tube has been used for reconstruction after esophagectomy.

Aged↗