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Biomedical subjects

K Yamada

Publications and source records attributed to K Yamada.

At least 217 records · Page 12Linked to original sources
PubMed2001

Preoperative assessment of vascularity by color Doppler ultrasonography in human rectal carcinoma.

PURPOSE: Although angiogenesis assessed by immunostaining endothelial cells (microvessel density) is a well-known prognostic factor in a wide variety of human solid tumors, preoperative determination of microvessel density seems to be difficult in rectal carcinoma. Thus, we performed transanal color Doppler ultrasonography in 46 patients with rectal carcinoma to assess preoperative angiogenic status and compare it with microvessel density in surgical specimens. METHODS: Time-averaged maximal velocity, peak systolic velocity, number of vascular points, and vascular point index were conducted by color Doppler ultrasonography in 46 patients with rectal carcinoma. Number of vascular points was defined as the number of vessels with pulsation in the section of tumor. Vascular point index was defined as the average number of vascular points divided by the area assessed by color Doppler ultrasonography in the section of tumor. The profiles of number of vascular points were similar to those assessed by microangiography in five rectal carcinomas. RESULTS: Vascular point index significantly correlated with microvessel density (P < 0.0001). No significant correlation was found between microvessel density and time-averaged maximal velocity or peak systolic velocity. Vascular point index was also a better indicator of lymph node metastasis and venous invasion than microvessel density. In addition, 11 of 46 cases with postoperative hematogenous metastasis (23.9 percent) were observed prospectively. Vascular point index may be a best predictor for hematogenous metastasis from rectal carcinoma compared with peak systolic velocity, time-averaged maximal velocity, and microvessel density by receiver operating characteristic analysis. CONCLUSION: These results suggest that preoperative quantification of angiogenesis using color Doppler ultrasonography will provide quick and useful information in the management of rectal carcinoma.

Blood Flow Velocity↗
PubMed2001

Inhibition of environmental estrogen-induced proliferation of human breast carcinoma MCF-7 cells by flavonoids.

In the present study, we evaluated the individual and combined effects of environmental estrogens and flavonoids on the proliferation of human breast carcinoma MCF-7 cells. These compounds are as follows: (1) pharmaceutical chemicals such as diethylstilbestrol, 17alpha-ethynylestradiol (17ES), tamoxifen, mestranol, and clomiphene, (2) industrial chemicals such as bisphenol A (BisA), 4-octylphenol (OP), 4-nonylphenol (NP), and p,p'-biphenol, and (3) flavonoids such as daidzein (D), genistein (G), quercetin (Q), and luteolin (L). We found that nanomolar concentrations of 17ES, BisA, OP, and NP were sufficient to stimulate the proliferation of MCF-7 cells. Among them, 1 microM BisA exhibited cell proliferation-stimulating activity as strong as 10 nM 17beta-estradiol; and D and G exhibited cell proliferation-stimulating activity at 10 nM. On the other hand, Q and L exhibited cell proliferation-inhibiting activity. We also found that 10 nM flavonoids, such as D, G, Q, and L, were able to inhibit the proliferation-stimulating activity in MCF-7 cells by 1 microM environmental estrogens.

Breast Neoplasms↗
PubMed2001

A new glucose-6-phosphate dehydrogenase variant G6PD Sugao (826C-->T) exhibiting chronic hemolytic anemia with episodes of hemolytic crisis immediately after birth.

A case of glucose-6-phosphate dehydrogenase (G6PD) deficiency associated with chronic hemolysis with episodes of hemolytic crisis immediately after birth is reported. The propositus was a 1-month-old Japanese male infant. Molecular analysis of the G6PD gene revealed a novel missense mutation (826C-->4T) in exon 8 predicting a single amino acid substitution, Pro276Ser. The mother was confirmed to be heterozygous for this mutation. We designated this novel class 1 variant as G6PD Sugao. Pro276 is a phylogenetically conserved residue that may play a significant role in dimer formation.

Anemia, Hemolytic, Congenital↗
PubMed2001

Recombinant expression of perchloric acid-soluble protein reduces cell proliferation.

Perchloric acid-soluble protein (PSP) may play an important role in the regulation of cellular physiological functions because it has been highly conserved throughout evolution; however, this role has not been well elucidated. In previous reports, we suggested that PSP regulates cell proliferation. In this study, we examined the effect of PSP expression on proliferation of the normal rat kidney cell line NRK-52E, the rat hepatocyte cell line RLN-10, and the rat hepatoma cell line dRLh-84. Cells transfected with pcDNA-sense-PSP (pcDNA-S-PSP) over-expressed PSP mRNA and protein, and cell proliferation of the transfected cells was suppressed compared with that of cells transfected with pcDNA-empty (pcDNA-E). Cell viability of pcDNA-S-PSP-transfected cells was similar to that of pcDNA-E-transfected cells. Thus, over-expression of PSP suppresses cell proliferation without any influence on cell viability. These findings are the first to report an inhibitory activity of PSP on cell proliferation.

Animals↗
PubMed2001

Inhibitory effect of SM-20550, an Na+/H+ exchange inhibitor, on accumulation of leukocytes in ischemia and reperfusion.

The effect of an Na+/H+ exchange inhibitor, SM-20550, on the adhesion, emigration and accumulation of leukocytes was studied in ischemia and reperfusion injury models using rat mesenteric venules or rabbit heart. Anesthetized rats underwent occlusion of the superior mesenteric artery (20 min) followed by reperfusion (60 min). After ischemia and reperfusion, the numbers of adherent and emigrated leukocytes increased significantly. Bolus intravenous administration of SM-20550 reduced the numbers of adherent and emigrated leukocytes in a dose-dependent manner, with statistical significance at dosages >0.1 mg/kg. Anesthetized rabbits underwent occlusion of the coronary artery (30 min) followed by reperfusion (5 h). Intravenous administration of SM-20550 before ischemia significantly reduced the neutrophil accumulation in the area-at-risk by 46% and reduced the infarct size by 38%. These results suggest that the inhibitory effect of SM-20550 on the neutrophil accumulation could be one of the mechanisms by which this drug limits the severity of infarctions.

Amidines↗
PubMed2001

An intracranial aspergilloma with low signal on T2-weighted images corresponding to iron accumulation.

We present a case of cerebral aspergillosis in an immunocompetent patient. The MRI signal characteristics were compared with the histologic findings. Irregular low-signal zones were demonstrated between the wall of the abscess and the central necrosis on T2-weighted images; the pathology specimen revealed concentrated iron in these transitional zones but no hemosiderin. Iron is an essential element for the growth of fungal hyphae. The low-signal zones may represent the areas where there was active proliferation of aspergillus, and the unique location of the low signal may be a helpful imaging characteristic for the diagnosis of an aspergillus abscess.

Adult↗
PubMed2001

Efficient production of saikosaponins in Bupleurum falcatum root fragments combined with signal transducers.

An efficient system to produce saikosaponins (saikosaponin-a and -d) in Bupleurum falcatum adventitious root fragments combined with signal transducers was developed. The roots are heterogeneous in terms of size and shape and sometimes form aggregates during cultivation. When the roots were cut to lengths of about 5 mm using a scalpel and cultivated, the root fragments did not form the aggregates, and root growth and saikosaponin production were not inhibited. After screening various signal transducers, it was clear that methyl jasmonate (MeJA) markedly promoted saikosaponin production. By comparing the effect of MeJA and related substances on saikosaponin production, we conclude that both the pentenyl and carboxylmethyl group of MeJA play an important role in the promotion of saikosaponin production. Addition of both 100 microM MeJA and 20 mM CaCl2 to the medium stimulated the content of saikosaponin in the root, with levels reaching 31.7 mg/g-dry root for 15 days of cultivation. A large amount of root fragments were prepared using a blender and cultivated (23 g-dry root/l) with 400 microM MeJA and 20 mM CaCl2, resulting in a high concentration of saikosaponins (747.3 mg/l).

Acetates↗
PubMed2001

Advantage of delayed whole-body FDG-PET imaging for tumour detection.

Delayed imaging that coincides with the highest uptake of fluorine-18 fluorodeoxyglucose (FDG) by tumour may be advantageous in oncological positron emission tomography (PET), where delineation of metastasis from normal tissue background is important. In order to identify the better imaging protocol for tumour detection, whole-body FDG-PET images acquired at 1 h and 2 h after injection were evaluated in 22 subjects, with a post-injection transmission scan at 90 min for attenuation correction. After visual interpretation, tumour uptake [tumour standardised uptake ratio (SUR)], normal tissue uptake (normal SUR) and tumour to background contrast (tumour SUR/normal tissue SUR) were evaluated in the images acquired at 1 h and at 2 h. Most malignant lesions, including primary lung cancer, metastatic mediastinal lymph nodes and lymphoma lesions, showed higher FDG uptake at 2 h than at 1 h. By contrast, benign lesions, with the exception of sarcoidosis, showed lower uptake of FDG at 2 h than at 1 h. Among normal tissues, the kidney, liver, mediastinum, lung, upper abdomen and left abdomen showed significant falls in FDG uptake from 1 h to 2 h. The lower abdomen, right abdomen and muscles (shoulder and thigh) showed no significant changes. Consequently, malignant lesions of the lung, mediastinum and upper abdomen showed significant increases in tumour to background contrast from 1 to 2 h. Three lesions (two lung cancers and a malignant lymphoma) that were equivocal on 1-h images became evident on 2-h images, changing the results of interpretation. All other malignant lesions were detected on 1-h images, but were clearer, with higher contrast, on 2-h images. Lesion-based sensitivity was improved from 92% (49/53) to 98% (52/53), and patient-based sensitivity from 78% (14/18) to 94% (17/18). It is concluded that delayed whole-body FDG-PET imaging is a better and more reliable imaging protocol for tumour detection.

Fluorodeoxyglucose F18↗
PubMed2001

Establishment of pulmonary alveolar type II cell line from p53-deficient mice.

We obtained a pulmonary alveolar type II epithelial cell line, MAC7, derived from the lung of p53-deficient mice (p53 -/-). When this cell line was passaged for long periods of time, the epithelial cells grew at a high rate for over 50th passage and never entered the non-growing senescent phase characteristic of the normal cells (p53 +/+). Each pulmonary epithelial outgrowth was characterized morphologically and immunocytochemically, and the growth and viability of the outgrowths were examined by MTT assay. Expression of surfactant-associated protein, SP-B, was detected, and transmission electron microscopy demonstrated a type II phenotype containing lamellar bodies and phospholipids. These findings indicate that MAC7 cells retain the morphological and physiological properties of alveolar type II epithelial cells. This cell line should be useful in experimental systems for studying lung pathology.

Animals↗
PubMed2001

Effects of propofol and thiopental on the central nervous system during nociceptive stimulation in cats.

PURPOSE: Nociceptive stimulation may increase central nervous system (CNS) activity during anesthesia. However, it is not known whether propofol and thiopental have a similar inhibitory effect on the CNS during nociceptive stimulation. Therefore, we compared the antinociceptive effects of propofol and thiopental in cats. METHODS: In 12 cats, anesthesia was induced with 4% halothane in oxygen and maintained with 0.5% halothane in oxygen. The cortical electroencephalogram (EEG) and the electrical activity from the midbrain reticular neurons (R-MUA) were measured before and after sciatic nerve stimulation. The cats were then allocated to receive cumulative doses of either propofol (n = 6) or thiopental (n = 6) i.v. at 5-min intervals. Two minutes after each dose, the cortical EEG and the R-MUA were compared before and after sciatic nerve stimulation. RESULTS: Propofol and thiopental depressed the basal R-MUA to a similar degree at each dose. Sciatic nerve stimulation increased the R-MUA, and there were no differences in the maximum R-MUA values between propofol and thiopental. The cortical EEGs after each dose of anesthetic without stimulation showed similar patterns, and the patterns of change with stimulation were also similar for these two anesthetics. CONCLUSION: Propofol and thiopental have similar antinociceptive effects in cats.

Journal Article↗
PubMed2001

Cyst fluid levels of carcinoembryonic antigen, carbohydrate antigen 19-9, squamous cell carcinoma antigen, and amylase in thyroglossal duct and branchial cleft cysts.

Cyst fluid was aspirated from five thyroglossal duct cysts (TDCs) and four branchial cleft cysts (BCCs). The cyst fluid levels of carcinoembryonic antigen (CEA), carbohydrate antigen (CA) 19-9, squamous cell carcinoma antigen (SCC), and amylase were measured and compared between the two types of cyst. The enzyme immunoassay technique was used for CEA and CA19-9, while SCC and amylase levels were measured by the immunoradiometric assay and nitrophenol method, respectively. Immunostaining for CEA, CA19-9, and amylase was also performed. The serum levels of these markers in both groups of patients were within the normal ranges. In contrast, their cyst fluid levels were extremely high. There was no significant difference in the cyst fluid levels of CEA and SCC between the two types of cyst; however, the cyst fluid from the TDCs showed significantly higher levels of CA19-9 and significantly lower levels of amylase compared with that from the BCCs. Immunostaining revealed expression of CA 19-9 in nearly half the columnar epithelial cells in the TDCs, but not in the squamous epithelial cells in the BCCs. CEA and amylase were not found in the epithelial cells of either type of cyst. These findings seem to reflect the difference in etiology between TDCs and BCCs.

Adult↗
PubMed2001

Long-term outcomes of immunosuppressed renal transplant recipients with malignancies.

This study analyzes ten cases of malignancy in a cohort of 183 renal transplant recipients, examining surgical management, postoperative immunosuppressive therapy, and long-term outcome. One of these ten patients, who had malignant lymphoma of the jejunum, died of the neoplasm, but the other nine patients did not show any signs of tumor recurrence after removal. All of these nine patients, except for one who had transplant renal cell carcinoma (RCC), received the same dose of immunosuppressive agents after surgery for the malignant disease. Seven patients were still alive at the time of this report, six of whom had good transplant renal function. The findings of this study indicate that even if immunosuppressive agents predispose to the development of cancer, it is not necessary to reduce their dose after removal of the tumor.

Adult↗
PubMed2001

Successful surgical treatment of renal cell carcinoma in a transplanted kidney from a cadaveric donor: report of a case.

Posttransplant renal cell carcinoma (RCC) usually arises in the native kidneys of renal transplant recipients rather than in the transplanted kidney. This report describes a case of RCC that developed in the transplanted cadaveric kidney in a 37-year-old male recipient 9 months after transplantation. An en bloc radical transplant nephrectomy was performed, and he has subsequently remained stable on hemodialysis for 3 years without any sign of recurrence.

Adenocarcinoma↗
PubMed2001

Surgical treatment of chronic subdural hematoma based on intrahematomal membrane structure on MRI.

BACKGROUND: To determine the optimal surgical management of chronic subdural hematoma (CSDH), we assessed which operative procedure, burr holes or small craniotomy, was more effective on 49 consecutive patients. METHOD: We retrospectively classified all cases into two groups according to the intrahematomal membrane structure of CSDH on T2*-weighted magnetic resonance (MR) imaging. The first group, labeled type B, included hematomas which had no intrahematomal membrane and/or were monolayer multilobule. The second group, labeled type C, consisted of hematomas which were divided into multiple layers by the intrahematomal membrane. FINDINGS: The outcome of type C patients treated with burr holes was significantly inferior to that of those who underwent a small craniotomy in terms of the relative outcome of neurological grading. re-operation ratio, and postoperative hospital stay (p < 0.05). Type C hematomas treated with burr holes also had inferior outcome compared with a small craniotomy in terms of the duration of hematoma until disappearance on postoperative CT (p < 0.05). INTERPRETATION: We concluded that a considerable number of cases appeared to need craniotomy and resection of intrahematomal membrane for complete recovery in CSDH, and that T2*-weighted MR imaging could be used as a basis for selecting the operative procedure for CSDH.

Adult↗
PubMed2001

Spatial memory deficit and neurodegeneration induced by the direct injection of okadaic acid into the hippocampus in rats.

We investigated the effects of okadaic acid (OA), a specific inhibitor of protein phosphatases 1 and 2A, on spatial memory and neuronal survival in rats. Rats were initially trained on a spatial memory task in an eight arm radial maze. Spatial reference and working memory was impaired 1 day after the unilateral microinjection of OA into the dorsal hippocampus. The impairment was transient, and had disappeared by the following day. In contrast, neurodegeneration induced by OA was persistent and extended to the contralateral side 13 days after the injection. These results suggest that OA causes spatial memory impairment and neurodegeneration when injected directly into the hippocampus. Our findings also indicate dissociation between memory impairment and neurodegeneration induced by OA.

Animals↗
PubMed2001

Memory deficits and increased emotionality induced by beta-amyloid (25-35) are correlated with the reduced acetylcholine release and altered phorbol dibutyrate binding in the hippocampus.

In the present study we found that chronic infusion of beta-amyloid fragment (25-35) at nanomolar concentration into rat cerebral ventricle impairs learning and memory. At a concentration of 3 nmol/day but not 0.3 nmol/day, beta-amyloid significantly reduced the spontaneous alternation behavior and the memory performance in the water maze and multiple passive avoidance tests. A significant increase in anxiety was also found in the animals infused with 3 nmol/day beta-amyloid fragment. Memory deficits and the increased emotionality were correlated with a decreased nicotine-evoked acetylcholine release from the frontal cortex/hippocampus, as assessed by microdialysis, in freely moving rats. The amyloid fragment infused either at pico- or nanomolar concentrations reduced the affinity of [3H] phorbol dibutyrate binding, an index of activated protein kinase C (PKC), and increased the total number of binding sites in the hippocampal particulate fraction. Our results suggest that the amnesic and anxiogenic effects of chronic infusion of beta-amyloid (25-35) are related to the decreased acetylcholine release and reduced PKC activation.

Acetylcholine↗