Biomedical subjects

R Yamamoto

Publications and source records attributed to R Yamamoto.

At least 55 records · Page 3Linked to original sources

PubMed2001

Supporting medical decisions with vector decision trees.

The article presents the extension of a common decision tree concept to a multidimensional - vector - decision tree constructed with the help of evolutionary techniques. In contrary to the common decision tree the vector decision tree can make more than just one suggestion per input sample. It has the functionality of many separate decision trees acting on a same set of training data and answering different questions. Vector decision tree is therefore simple in its form, is easy to use and analyse and can express some relationships between decisions not visible before. To explore and test the possibilities of this concept we developed a software tool--DecRain--for building vector decision trees using the ideas of evolutionary computing. Generated vector decision trees showed good results in comparison to classical decision trees. The concept of vector decision trees can be safely and effectively used in any decision making process.

Algorithms↗

PubMed2000

Prophylactic action of oral fluconazole against fungal infection in neutropenic patients. A meta-analysis of 16 randomized, controlled trials.

BACKGROUND: Fluconazole is used widely for fungal prophylaxis. Although studies with bone marrow transplantation (BMT) recipients clearly showed the usefulness of oral fluconazole, results of the studies in neutropenic patients other than BMT recipients have been inconsistent. Therefore, the authors performed a meta-analysis to evaluate the efficacy of fluconazole prophylaxis during chemotherapy-induced neutropenia. METHODS: The authors identified reports that were not restricted to those in English and not restricted to published trials through MEDLINE, CANCERLIT, or the data base of the Pfizer company. The authors included prospective, randomized studies comparing oral fluconazole with placebo, no treatment, or oral polyenes as prophylaxis for fungal infections in neutropenic patients. Two independent authors extracted data from 16 trials with 3734 patients enrolled. The outcome measures were the development of fungal-related death, systemic and superficial fungal infections, the use of empiric intravenous amphotericin-B, and infections or colonization with fluconazole-resistant fungi. The summarized odds ratios (ORs) were calculated using the Mantel-Haenszel method and the DerSimonian-Laird method. RESULTS: Prophylactic fluconazole was not effective in reducing fungal-related death or in reducing proven, systemic fungal infections in non-BMT patients (OR, 0.91; 95% confidence interval [CI], 0.30-2.82 and OR, 0.85; 95% CI, 0.47-1.55, respectively). However, fluconazole was very effective in reducing superficial fungal infections (OR, 0.44; 95% CI, 0.24-0.80), even when it was given in lower doses (50-200 mg per day). There was no increase in proven, systemic infection of fluconazole-resistant fungi, although colonization of those fungi increased. When the results were combined in studies in which the incidence of systemic fungal infections was > 15%, fluconazole was effective in reducing such infections (OR, 0.23; 95% CI, 0.15-0.36). CONCLUSIONS: The current analyses failed to find an effect of fluconazole on both fatal fungal infection and systemic fungal infection in non-BMT patients. Further studies on severely neutropenic patients are warranted because prophylactic fluconazole seemed to be effective when the incidence of systemic fungal infection was expected to be > 15%.

Administration, Oral↗

PubMed2000

Adrenomedullin receptors in rat cerebral microvessels.

To characterize the sites of action of adrenomedullin (AM) in the cerebral microvasculature, we studied the effect of AM on cyclic AMP (cAMP) level as well as expression of AM and its receptor in the rat cerebral microvessels. The microvessels were prepared from rat cerebral cortex by albumin flotation and glass bead filtration technique. AM and calcitonin gene-related peptide (CGRP) increased cAMP level in the microvessels in a concentration-dependent manner. The effect of AM was more than 100 times more potent than that of CGRP. The accumulation of cAMP by AM was inhibited by AM[22-52], an AM receptor antagonist, but not by CGRP[8-37], a CGRP receptor antagonist, suggesting that AM increased cAMP accumulation by acting on receptors specific to AM. [125I]AM binding to the microvessels was displaced by AM and less potently by AM[22-52]. The displacing potencies of CGRP and CGRP[8-37] were very weak. mRNAs for AM as well as calcitonin-receptor-like receptor and receptor-activity-modifying protein 2 which form a receptor specific to AM, were highly expressed in the microvessels. These results provide biochemical and pharmacological evidence that AM is produced in and acts on the cerebral microvessels in an autocrine/paracrine manner and is involved in regulation of cerebral microcirculation.

Adrenomedullin↗

PubMed2000

alpha(1)-Adrenergic receptor subtypes in rat cerebral microvessels.

To identify alpha(1)-adrenergic receptor subtypes involved in the regulation of cerebral microcirculation, we studied alpha(1)-adrenergic receptor subtypes expressed in the rat cerebral microvessels. The microvessels were prepared from rat cerebral cortex by albumin flotation and glass bead filtration techniques. [(125)I]HEAT binding to the cerebral microvessels was displaced by low concentrations of 5-methylurapidil, a selective antagonist for alpha(1A)-receptors, and modified Scatchard analysis of the data revealed that half of alpha(1)-receptors is alpha(1A)-subtype, and that alpha(1B)- and/or alpha(1D)-receptors are also present. The K(i) value of the high-affinity component for 5-methylurapidil was 3.90+/-1.08 nM, which is comparable with the value obtained in the rat cerebral cortex (2.17+/-0.88 nM). Reverse transcription and polymerase chain reaction experiments showed that mRNAs of alpha(1A)- and alpha(1B)-receptors, but not alpha(1D)-receptors, were expressed in the cerebral microvessels. These results suggest that alpha(1)-receptors involved in the regulation of cerebral microvessel function are alpha(1A)- and alpha(1B)-receptor subtypes.

Adrenergic alpha-Antagonists↗

PubMed2000

Pyrrolidine dithiocarbamate inhibits TNF-alpha-dependent activation of NF-kappaB by increasing intracellular copper level in human aortic smooth muscle cells.

Pyrrolidine dithiocarbamate (PDTC) is a metal-chelating compound that acts as antioxidant or pro-oxidant and is widely used to study redox regulation of cell function. In the present study, we investigated effects of PDTC and another antioxidant, N-acetyl-l-cysteine (NAC), on TNF-alpha-dependent activation of NF-kappaB in human aortic smooth muscle cells (HASMC). Treatment of the cells with TNF-alpha induced the activation of p65/p50 heterodimer NF-kappaB and increased the mRNA levels of monocyte chemoattractant protein (MCP)-1. Pretreatment with PDTC markedly suppressed the NF-kappaB activation and expression of MCP-1 by inhibiting IkappaB-alpha degradation. In contrast, NAC had no effect. PDTC concomitantly increased the intracellular levels of copper, and bathocuproinedisulfonic acid, a non-cell-permeable chelator of Cu(1+), inhibited the PDTC-induced increase in intracellular copper level and reversed the PDTC effects on IkappaB-alpha, NF-kappaB, and MCP-1. These results indicate that TNF-alpha-dependent expression of MCP-1 in HASMC is tightly regulated by NF-kappaB and that intracellular copper level is crucial for the TNF-alpha-dependent activation of NF-kappaB in HASMC.

Acetylcysteine↗

PubMed2000

Inhibition by neuroprotective drug NS-7 of nicotine-induced 22Na(+) influx, 45Ca(2+) influx and catecholamine secretion in adrenal chromaffin cells.

In cultured bovine adrenal chromaffin cells, NS-7 [4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy) pyrimidine hydrochloride], a newly-synthesized neuroprotective drug, inhibited nicotine-induced 22Na(+) influx via nicotinic receptors (IC(50)=15.5 microM); the suppression by NS-7 was observed in the presence of ouabain, an inhibitor of Na(+),K(+)-ATPase, and was not attenuated upon the washout of NS-7. NS-7 decreased nicotine-induced maximum influx of 22Na(+) without altering the EC(50) value of nicotine. Also, NS-7 diminished nicotine-induced 45Ca(2+) influx via nicotinic receptors and voltage-dependent Ca(2+) channels (IC(50)=14.1 microM) and catecholamine secretion (IC(50)=19.5 microM). These results suggest that NS-7 produces noncompetitive and long-lasting inhibitory effects on neuronal nicotinic receptors in adrenal chromaffin cells, and interferes with the stimulus-secretion coupling.

Adrenal Glands↗

PubMed2000

Effect of P(2)' site tryptophan and P(20)' site deletion of Momordica charantia trypsin inhibitor II on inhibition of proteinases.

Momordica charantia trypsin inhibitor II (MCTI-II) inhibits the amidolytic activity of factor Xa with a K(i) value 10-100-fold smaller than those of other squash family inhibitors. It also inhibits factor X activation mediated by factor VIIa-tissue factor complex or factor IXa. Comparison of other squash family inhibitors reveal Trp at position 7 (P(2)') and a deletion at position 25 (P(20)') are characteristics of MCTI-II. In order to elucidate the effect of these positions on the inhibitory activity, we chemically synthesized three inhibitors: S-MCTI-II whose amino acid sequence is identical to natural MCTI-II, S-MCTI-II(7L) whose P(2)'(Trp) is substituted with Leu, and S-MCTI-II(25N) whose P(20)'(deletion) is filled with Asn. The dissociation constants of the complexes of human factor Xa with S-MCTI-II, S-MCTI-II(7L), and S-MCTI-II(25N) were 1.3x10(-6) M, 2.8x10(-5) M, and 7.3x10(-6) M, respectively. They inhibited factor X activation mediated by factor VIIa with the same degree. As in the case of natural MCTI-II, S-MCTI-II suppressed factor X activation mediated by factor IXa, while S-MCTI-II(7L) and S-MCTI-II(25N) did not. Both the Trp at the P(2)' position and deletion at the P(20)' position are thus likely required for the inhibition of factor Xa, trypsin, and factor IXa, while these two positions do not affect factor X activation initiated by the factor VIIa-tissue factor complex.

Amino Acid Sequence↗

PubMed2000

The clinical significance of CD34 expression in response to therapy of patients with acute myeloid leukemia: an overview of 2483 patients from 22 studies.

BACKGROUND: Although many studies have been performed to evaluate the prognostic significance of CD34 expression in acute myeloid leukemia (AML), the findings have been inconsistent. In this study, the authors reviewed such previous studies to establish a definite conclusion. METHODS: Using MEDLINE, the authors identified studies that evaluated the prognostic significance of CD34 expression in AML. The outcome measure was the complete remission rate. They used the random-effect method to combine the results. Results were presented as odds ratios (ORs) with 95% confidence intervals (CIs). The ORs were less than 1 if the complete remission occurred more frequently in the CD34 negative group. RESULTS: Twenty-two studies including 2483 patients were reviewed. The combined OR was 0.38 (95% CI, 0. 26-0.57), which suggested that CD34 expression was associated with a poor remission rate. However, the authors found statistical evidence of marked heterogeneity among trials (P < 0.001), especially according to time of publication. The combined OR in studies published in or after 1994 was 0.70 (95% CI, 0.47-1.09). The authors divided the studies into several subgroups, but they could not determine the reason for the heterogeneity. CONCLUSIONS: At present, CD34 expression should not be considered a marker of poor prognosis because it is not supported by the combined data from recent studies. Further studies should be conducted to investigate the intensity of CD34 expression in specific populations of patients, such as those with t(8;21) or t(15;17) translocations or the AML-M0 subtype.

Acute Disease↗

PubMed2000

A multivariate analysis of blood vessel and lymph vessel invasion as predictors of ovarian and lymph node metastases in patients with cervical carcinoma.

BACKGROUND: To the authors' knowledge there are few available data regarding the influence of lymphovascular space invasion, which has been examined separately as two components (lymphatic vessel invasion [LVI] and blood vessel invasion [BVI]), in the metastasis of cervical carcinoma. METHODS: LVI and BVI, which include capillary vessel invasion, were reviewed retrospectively based on the histopathologic slides of 239 women with cervical carcinoma who were treated with radical hysterectomy. The correlation between lymph node and/or ovarian metastases and LVI, BVI, and other histopathologic factors was investigated by multiple logistic regression analysis. The influence of LVI and BVI on survival was examined by Cox regression analysis. RESULTS: The rate of incidence of LVI was higher than that of BVI in all stages of cervical carcinoma (P < 0.0001 for International Federation of Gynecology and Obstetrics Stage IB and Stage II disease and P < 0.05 for Stage III disease). The incidence rate of BVI increased as LVI became more prominent and there was a significant correlation between the two findings (P < 0.0001). BVI was more frequent in adenocarcinoma/adenosquamous carcinoma than in squamous cell carcinoma (P < 0.05). LVI (P < 0.0001) and parametrial invasion (P < 0.0001) were significantly related to lymph node metastasis on multivariate analysis. Conversely, BVI (P < 0.05) and parametrial invasion (P < 0.0025), as well as adenocarcinoma or adenosquamous carcinoma (P < 0.0005), were significantly related to ovarian metastasis on multivariate analysis. With regard to the prognostic significance of these components, it was found that BVI (hazards ratio [HR] = 2.0), ovarian metastasis (HR = 6.5), and lymph node metastasis (HR = 5.5) were significantly related to a poor prognosis in women with cervical carcinoma. CONCLUSIONS: Ovarian metastasis may occur via hematogenous spread of cervical carcinoma. The results of the current study suggest that BVI, including capillary vessels, that is diagnosed separately from LVI using hematoxylin and eosin stained sections may be an important prognostic factor for patients with cervical carcinoma.

Carcinoma, Adenosquamous↗

PubMed2000

High serum lactate dehydrogenase level predicts short survival after vincristine-doxorubicin-dexamethasone (VAD) salvage for refractory multiple myeloma.

We evaluated possible prognostic factors just before salvage therapy with vincristine, doxorubicin, and dexamethasone (VAD) for 36 patients with refractory multiple myeloma. The median duration from diagnosis to the first VAD salvage was 14 months (range 2-76 months). Among parameters that have been shown to be associated with poor survival, a high serum lactate dehydrogenase (LDH) level was the sole significant predictor of survival. The median survival of patients with high LDH levels was 4 months, whereas that of patients with low LDH levels was 20 months. A multivariate analysis identified high LDH and high age as independent prognostic factors. More aggressive therapies might be indicated for high-LDH patients with refractory myeloma.

Adult↗

PubMed2000

Two cases of endometrial cancer meeting new clinical criteria for hereditary nonpolyposis colorectal cancer.

BACKGROUND: New clinical criteria for hereditary nonpolyposis colorectal cancer (HNPCC) that includes extracolonic cancers were recently proposed. We present 2 endometrial cancer patients who met the new criteria of 161 endometrial cancer patients. CASE REPORTS: Case 1: A 55-year-old female was operated on for synchronous double primary cancers of the endometrium and rectum. She had also undergone an operation for metachronous ascending colon cancer at the age of 44. She had five relatives with a history of colorectal cancer. The rectal cancer tissue revealed no microsatellite instability (MSI). Case 2: A 48-year-old female underwent a radical operation for synchronous double primary cancers of the endometrium and ovaries. She had three relatives with a history of colorectal cancer. The endometrial cancer tissue showed high MSI. CONCLUSIONS: The frequency of endometrial cancer patients meeting the new HNPCC criteria was 1.2% (2/161). These are the first case reports selected from consecutive endometrial cancer patients.

Carcinoma, Endometrioid↗

PubMed2000

Complications relating to intraperitoneal administration of cisplatin or carboplatin for ovarian carcinoma.

BACKGROUND: Complications associated with intraperitoneal (ip) chemotherapy is one of the factors that should be taken into consideration upon performing long-term intraperitoneal administration of chemotherapeutic agents for ovarian carcinoma. METHODS: From 1987 to 1996, 78 patients with primary ovarian carcinoma were treated with a total of 365 courses of ip administration of cisplatin (CDDP) or carboplatin (CBDCA) as a part of an initial chemotherapy regimen in combination with surgery including systematic retroperitoneal lymph node dissection using an implantable peritoneal cavity access catheter system. The complications that occurred in association with ip chemotherapy were analyzed. RESULTS: Complications associated with ip chemotherapy were seen in 27 of 78 (34.6%) patients, which included extensive intestinal adhesion, abdominal pain, local infection, ileus, bleeding at the site of implanted port, obstruction of the catheter, vaginal vault perforation, and bowel perforation. Major complications that required surgical treatment occurred in 3 patients, which included ileus, vaginal perforation, and an intestinal perforation. The perforations occurred after 18 and 36 months after the implantation of the catheter, respectively. CONCLUSIONS: It has been suggested that primary CDDP/CBDCA ip chemotherapy using an implantable catheter system can be carried out safely with rare major complications if employment of this method is restricted in 12 months after the installation of catheter.

Adult↗

PubMed2000

Malignant solitary fibrous tumor in the pleura.

We present a case of malignant solitary fibrous tumor of the pleura in an asymptomatic 75-year-old man. A needle biopsy specimen revealed a solitary fibrous tumor of the pleura with suspected. The tumor was resected and the final diagnosis was a malignant solitary fibrous tumor. At one-and-a-half years later, the patient has no clinical or radiological evidence of recurrence. The propriety of a needle biopsy for preoperative diagnosis is discussed.

Aged↗

PubMed2000

Neuroblastoma resection in an adult with a 10-year history of chest-mass shadow.

Neuroblastoma is rare in adults. We encountered this tumor in an asymptomatic 21-year-old man with a 10-year history of a mass-like shadow in chest radiography. Diagnosis was confirmed after resection, and 60 Gy radiation therapy was started. One year later, the patient has no clinical or radiological evidence of recurrence.

Adult↗

PubMed2000

Mortality and cancer incidence in patients with Parkinson's disease.

To investigate the risks of mortality and cancer incidence in Parkinson's disease (PD) we studied the prognosis of 246 PD patients in a community. The cohort of PD patients was identified in 1984, and survival, mortality, relocation, and cancer incidence during 1984-1992 were examined retrospectively in 1994. The risk was measured by a standard effect estimate, i.e., the standardized mortality ratio (SMR) or the standardized incidence ratio (SIR), compared with the rates in the general population. During the observation period 696 person-years in PD men and 1018 person-years in PD women were accumulated, and 49 PD men and 53 PD women died. The risk of mortality in PD was significantly increased in both sexes (SMR: men 1.74, women 1.97). In addition, the risk of cancer incidence was evaluated in 228 patients aged under 80 years; 8 PD men and 7 PD women developed cancer. The risk of overall cancer incidence in PD was less than 1 in either sex, but not significantly. The risk of breast cancer in PD women was significantly increased (SIR: 5.49), but the 95% confidence interval was wide (1.10-16.03). The results indicate that PD patients in a community have a twofold higher risk of mortality, and that PD may be associated with an increased risk of breast cancer in women.

Adult↗

PubMed2000

Effects of preoperative chemotherapy and radiation therapy on human bronchial blood flow.

OBJECTIVE: We investigated the relationship between bronchial mucosal blood flow around the area of lung resection and the state of healing of the bronchial stump in patients after chemotherapy with or without radiation therapy. METHODS: Ninety patients with primary lung cancer were divided into the following 3 groups: group A, 72 patients who had no preoperative therapy; group B, 10 patients who had chemotherapy; and group C, 8 patients who had chemoradiation (60 Gy) therapy. Bronchial mucosal blood flow was measured preoperatively, intraoperatively, and postoperatively (days 8-10) with a laser Doppler flowmeter. RESULTS: In groups A and B bronchial mucosal blood flow was preserved sufficiently around the surgical site, and the healing of the bronchial stump was satisfactory. On the contrary, preoperative blood flow in group C was 70% of the preoperative value in group A and decreased further intraoperatively. Healing of the bronchial stump was poor, and a bronchopleural fistula occurred in one patient of group C. CONCLUSION: Preoperative chemoradiation therapy may adversely affect bronchial mucosal blood flow and healing of the bronchial stump, although lymphadenectomy and preoperative chemotherapy had little effect. It is recommended that the bronchial stump should be covered with pedicled viable tissue after chemoradiation therapy for prophylaxis against bronchial complications.

Adenocarcinoma↗

PubMed2000

Architecture for networked electronic patient record systems.

There have been two major approaches to the development of networked electronic patient record (EPR) architecture. One uses object-oriented methodologies for constructing the model, which include the GEHR project, Synapses, HL7 RIM and so on. The second approach uses document-oriented methodologies, as applied in examples of HL7 PRA. It is practically beneficial to take the advantages of both approaches and to add solution technologies for network security such as PKI. In recognition of the similarity with electronic commerce, a certificate authority as a trusted third party will be organised for establishing networked EPR system. This paper describes a Japanese functional model that has been developed, and proposes a document-object-oriented architecture, which is-compared with other existing models.

Computer Communication Networks↗

PubMed2000

Medical markup language (MML) for XML-based hospital information interchange.

Medical Markup Language (MML) has been developed over the last 6 years in order to create a set of standards by which medical data, within Japan and hopefully worldwide, can be stored, accessed and exchanged in any number of physical locates. The MML version 2.21 is characterized by XML as meta-language, module structure for each document and enhancement of linking function among documents. Data exchange specification has been also added for query and reply. MML instances are composed of MML header and MML body. The MML header includes information for data transmission, while MML body includes several module items. One module item contains two elements: document information and module content. Nine MML module contents are defined at the present time: patient information, health insurance information, diagnosis information, lifestyle information, basic clinic information, particular information at the time of first visit, progress course information, surgery record information and clinical summary information.

Clinical Laboratory Techniques↗