Biomedical subjects

E Yamamoto

Publications and source records attributed to E Yamamoto.

At least 19 recordsLinked to original sources

PubMed1995

Functional mapping of the human colour centre with echo-planar magnetic resonance imaging.

Clinical studies of cerebral achromatopsia have suggested a colour centre in the human fusiform gyrus. By using functional magnetic resonance imaging, we examined whether the fusiform gyrus shows activity correlated with the perception of colour. We tested three stimulus conditions in which the subject maintained fixation: (i) a circular array of six coloured circles; (ii) the same as (i) except that each circle is equiluminant grey with its colour counterpart; and (iii) the same as (i) plus a clockwise shift of circles to neighbouring positions every 1 s. After termination of the stimulus, the subject perceived an after-image of circles with complementary colours in (i), but not in (iii). In condition (i), we found a focal signal increase in the posterior part of the fusiform gyrus. In condition (ii), the activation in the same locus during the stimulation period was weaker than that in (i). In condition (iii), the signal intensity after termination of the stimulus was weaker than that in (i). The colour effect and after-effect on activation of the fusiform gyrus observed here suggest its critical role in human colour perception.

Brain Mapping↗

PubMed1995

Cloning of a human gene potentially encoding a novel matrix metalloproteinase having a C-terminal transmembrane domain.

Matrix metalloproteinases (MMPs) play key roles in tissue remodeling during physiological and pathological processes by degrading various extracellular matrix (ECM) components. Although nine distinct MMPs have been characterized by cDNA cloning, there are thought to be more corresponding to the complexity of the ECM. MMP genes expressed in human tissues and cell lines were analyzed by the polymerase chain reaction (PCR) using degenerate primers that corresponded to the conserved amino acid (aa) sequences of the MMPs. One isolated complementary DNA (cDNA) fragment had sequence homology to the reported MMPs, but was otherwise unique. A human placenta cDNA library (Clontech) was screened using the fragment as a probe and a 3.4-kb cDNA fragment containing a long open reading frame (potentially encoding 582 aa) was isolated. The putative gene product had a common domain structure and the conserved sequence of a MMP, but it had a unique transmembrane (TM)-like structure at the C terminus. It should, therefore, be an TM protein, whereas all the other reported MMPs are secretory proteins. Thus, the gene is thought to be the first of a new subclass of MMPs whose products are potentially expressed on the cell surface.

Adenocarcinoma↗

PubMed1995

Ingested arsenic and internal cancer: a historical cohort study followed for 33 years.

A historical cohort study was conducted to investigate the long-term effect of exposure to ingested arsenic. The 454 residents who had been identified in a list made in 1959 were followed until 1992. They lived in an arsenic-polluted area, called Namiki-cho, Nakajo-machi, in Niigata Prefecture, Japan, and used well water containing inorganic arsenic. The exposure period was estimated to be about 5 years (1955-1959). Death certificates for the people who died between 1959 and 1992 were examined, and a total of 113 of the 454 residents were estimated to have drunk well water containing a high dose of arsenic (> or = 1 ppm). The standardized mortality rate ratios of these 113 residents were 15.69 for lung cancer (observed/expected = 8/0.51; 95% confidence interval (CI) 7.38-31.02) and 31.18 for urinary tract cancer (observed/expected = 3/0.10; 95% CI 8.62-91.75). Cox's proportional hazard analyses demonstrated that the hazard ratios of the highest exposure level group (> or = 1 ppm) versus the background exposure level group (0.001 ppm) were 1.74 (95% CI 1.10-2.74) for all deaths and 4.82 (95% CI 2.09-11.14) for all cancers. The analysis according to the skin signs of chronic arsenicism in 1959 showed that they were useful risk indicators for subsequent cancer development. In the development of lung cancer, there was evidence of synergism between arsenic intake and smoking habit.

Adolescent↗

PubMed1995

Echo-planar diffusion spectroscopic imaging.

High-speed diffusion spectroscopic imaging based on an echo-planar technique is presented. A pair of diffusion gradients is applied prior to a rapidly oscillating magnetic field gradient which encodes both chemical shift and spatial information. By applying this technique to a phantom consisting of acetone and water, a diffusion spectroscopic image is obtained in about 15 min, about 64 times faster than the time required in the conventional method. The measured diffusion coefficients show good agreement with previously reported values. This kind of diffusion spectroscopic imaging is expected to provide a way to observe more specific metabolism.

Acetone↗

PubMed1995

Functional mapping of the human somatosensory cortex with echo-planar MRI.

The somatotopical organization of the human somatosensory cortex was analyzed with echo-planar imaging at 1.5 Tesla, utilizing deoxyhemoglobin as an endogenous contrast medium. Scrubbing stimulation at a frequency of 3 Hz was applied to one of three cutaneous areas: toes, fingertips, and tongue tip. Parasagittal echo-planar slices were obtained every 2 s. We found focal bands of increased signal intensity (4% on average) during the stimulation, with a rise time of 2-6 s. These activated bands were located on the contralateral postcentral gyrus. The cortical responses from the three stimulation sites were anatomically distinct and organized medially-to-laterally in the order of toes, fingertips, and tongue tip.

Adult↗

PubMed1995

Inhibitory effects of adhesion oligopeptides on the invasion of squamous carcinoma cells with special reference to implication of alpha v integrins.

We studied invasion-related adhesion events in vitro using three squamous carcinoma cell lines (HSC-3), poorly differentiated type; OSC-19, well-differentiated type; and KB cells, undifferentiated type). An in vitro invasion assay through matrigel in the transwell chamber revealed that HSC-3 cells were most invasive, OSC-19 cells moderately invasive and KB cells least invasive. Inhibition assay of invasion using synthetic peptides RGD, RGDV, RGDS, RGDT, IKVAV and YIGSR, showed that invasion of the three cell lines was significantly inhibited by RGDV. There were other peptides that inhibited invasion significantly including IKVAV for HSC-3, and RGDS and YIGSR for OSC-19. HSC-3 cells and OSC-19 cells adhered to fibronectin, laminin, vitronectin, and type IV collagen, and KB cells did not adhere to laminin but did to fibronectin, vitronectin and collagen type IV. Pretreatment of cells with RGDV peptide in the attachment assay reduced the ability of these cells to bind to vitronectin and fibronectin more efficiently than pretreatment with RGDS. Anti-alpha v antibodies inhibited adhesion of HSC-3, OSC-19 and KB cells to vitronectin, but anti-beta 1 antibodies did not inhibit adhesion. Immunofluorescent microscopic examinations showed that all cell lines were positive for anti-beta 5 and anti-alpha v antibodies, and only HSC-3 cells were positive for anti-beta 3 antibody. alpha 5 beta 1 was not clearly demonstrated in any of the cell lines. RGDV was the most effective inhibitor of squamous cell carcinoma invasion among the synthetic oligopeptides used in this experiment, and it is suggested that it affects alpha v beta 3- and/or alpha v beta 5-mediated carcinoma cell invasion.

Amino Acid Sequence↗

PubMed1995

Development of a new invasion and metastasis model of human oral squamous cell carcinomas.

A new model was devised in order to establish an in vivo model for oral carcinoma that exhibits significant local invasion and metastasis. One hundred and fifty-two nude mice had tumour cells from one of two established oral squamous cell carcinoma (SCC) cell lines (OSC-19 and OSC-20) implanted into the tongue or the oral floor via an intra-oral route and, as a control, the subcutaneous tissue of the back. The back tumours showed an expansive growth pattern, lacking significant invasion of surrounding tissues. In contrast, the tumours implanted into the tongue or the oral floor exhibited invasive growth and the histological appearance was similar to that of the original tumours. Moreover, regional neck lymph node and pulmonary metastases were observed in this model. Regional neck lymph node metastases were detected in 81.0% of mice implanted with OSC-19 cells and in 13.6% of mice implanted with OSC-20 cells. OSC-19 and OSC-20 cells showed pulmonary metastases in 9.5 and 9.1% of mice, respectively. These results suggest that this intra-oral implantation model is valuable in the study of the mechanism of invasion and metastasis of oral SCC.

Animals↗

PubMed1995

Factors affecting the occurrence of bacteremia associated with tooth extraction.

This study examined the factors that affect the occurrence of bacteremia associated with tooth extraction and the kinds of bacteria causing this bacteremia. Bacteremia was found in 132 (72.1%) of 183 patients who had one or more teeth extracted for various reasons. Bacteremia occurred more frequently when teeth were extracted because of inflammatory dental diseases. The occurrence of bacteremia also increased with the number of teeth extracted and the age of the patients. When the volume of blood lost during surgery was > 50 ml and the time required for the operation exceeded 100 min, the occurrence of bacteremia was also higher. Anaerobes were isolated from 104 (78.8%) of the 132 cases of bacteremia. Of the 187 isolates obtained, three (1.6%) were aerobes, 51 (27.3%) were facultative anaerobes (including microaerophils), and 133 (71.1%) were anaerobes. Among facultative anaerobes and microaerophils, the most frequently isolated bacterial genera were Lactobacillus (n = 15), Streptococcus (n = 13), and Staphylococcus (n = 12); and among anaerobes, Eubacterium (n = 40), Peptostreptococcus (n = 40), and Propionibacterium (n = 20).

Adolescent↗

PubMed1995

The slow progression of hepatic fibrosis in intrahepatic cholestasis as compared with extrahepatic biliary atresia.

It has been shown that the progression of hepatic fibrosis in intrahepatic cholestasis (IHC) is not so prominent as in extrahepatic biliary atresia (EHBA), and that the biosynthetic activity of collagen increases along with the fibrotic disease process. We conducted immunohistochemical and ultrastructural studies on the distribution of collagen types III and IV and of alpha-actinin in the smooth musculature in liver specimens obtained from 4 patients with IHC and 14 patients with EHBA in liver transplantation from living related donors (LRLT). A recently developed sandwich enzyme immunoassay (EIA) was used to determine serum concentrations of type IV collagen, laminin and prolyl 4-hydroxylase (PH) in the patients before and after LRLT. Pathological study showed that the excessive deposition of type IV collagen in the perisinusoidal walls resulted in a clearly developed basal membrane beneath the sinusoidal endothelial cells, so-called sinusoidal capillarization. In the fibrous septa of IHC, fibrogenesis was apparently lower than in EHBA, since collagen deposition and myofibroblast proliferation were not so prominent compared to EHBA. Serum type IV collagen, laminin and PH increased in IHC, although not so markedly as in EHBA, and returned to normal within 5 weeks after successful LRLT. In conclusion, it is suggested that an increased level of serum type IV collagen reflects the de novo synthesis of basal membrane components, and that the determination of their serum levels by EIA can be utilized for the differentiation of the specific fibrogenic activity in each disease, and for monitoring patients before and after liver transplantation.

Actinin↗

PubMed1995

The frequency of 4977 base pair deletion of mitochondrial DNA in various types of liver disease and in normal liver.

Using a polymerase chain reaction (PCR) method, we tested for the hepatic mitochondrial DNA (mtDNA) deletion in 40 hepatic tumors (28 hepatocellular carcinomas [HCCs], 9 other malignant tumors, and 3 benign tumors) and in the livers of 71 patients, including 16 pediatric patients with end-stage liver disease who underwent living related donor liver transplantation and 16 liver donors. A 4977 base pair (bp) deletion of mtDNA was detected in 36 of 55 specimens of non-tumor portions of adult liver (65.5%). However, none of the specimens obtained from cirrhotic livers of the 16 pediatric patients younger than 13 years of age had the 4977 bp deletion. The frequency of mtDNA deletion was significantly decreased compared with normal liver in HCCs (7 of 28) and other malignant liver tumors (2 of 9). The frequency of this deletion was unrelated to the presence of liver cirrhosis, patient's gender, hepatitis B virus surface antigen status, and hepatitis C virus antibody status.

Adolescent↗

PubMed1994

A matrix metalloproteinase expressed on the surface of invasive tumour cells.

Gelatinase A (type-IV collagenase; M(r) 72,000) is produced by tumour stroma cells and is believed to be crucial for their invasion and metastasis, acting by degrading extracellular matrix macro-molecules such as type IV collagen. An inactive precursor of gelatinase A (pro-gelatinase A) is secreted and activated in invasive tumour tissue as a result of proteolysis which is mediated by a fraction of tumour cell membrane that is sensitive to metalloproteinase inhibitors. Here we report the cloning of the complementary DNA encoding a new matrix metalloproteinase with a potential transmembrane domain. Expression of the gene product on the cell surface induces specific activation of pro-gelatinase A in vitro and enhances cellular invasion of the reconstituted basement membrane. Tumour cells of invasive lung carcinomas, which contain activated forms of gelatinase A, were found to express the transcript and the gene product. The new metalloproteinase may thus trigger invasion by tumour cells by activating pro-gelatinase A on the tumour cell surface.

3T3 Cells↗

PubMed1994

Methicillin-resistant Staphylococcus aureus endocarditis following patch closure of a ventricular septal defect: report of a case.

We report herein the case of a 5-month-old infant who, after developing methicillin-resistant Staphylococcus aureus (MRSA) endocarditis following patch closure of a ventricular septal defect (VSD), was successfully treated by replacement of the Dacron patch with an autogenous pericardial patch. Initially, a large perimembranous VSD was repaired with a Dacron patch and after an uneventful recovery of 1 week, he began to spike intermittent fevers from 38 degrees C to 39 degrees C. Two blood cultures grew MRSA and a two-dimensional echocardiogram performed 16 days after surgery showed an irregular mass attached to the right ventricular aspect of the Dacron patch. At reoperation, a large vegetation attached to the Dacron patch was confirmed, but there was no patch dehiscence. Following removal of the patch, the VSD was repaired with an autogenous pericardial patch, soon after which the fever rapidly subsided. Imipenem, 125 mg every 6 h, and fosfomycin, 300 mg every 6 h, were administered for a total of 24 days after reoperation. The child remains well 12 months after his second operation.

Endocarditis, Bacterial↗

PubMed1994

Infectious complications in living related liver transplantation.

During the last 31 months, 50 children between 3 months and 15 years of age have undergone living related liver transplantation (LRLT) for end-stage liver diseases (39 biliary atresia, 2 Budd-Chiari syndrome, 2 progressive intrahepatic cholestasis, 3 liver cirrhosis, 1 Wilson disease, 1 protoporphyria, 1 tyrosinemia, and 1 fulminant hepatitis). Combined FK-506 and low-dose steroids were routinely used for immunosuppression. There were seven deaths, two of which were related to infection (Candida pneumonia and Epstein-Barr virus [EBV]-associated lymphoproliferative syndrome [LPS]). Five patients had a bacterial infection, all of which were associated with surgical complications. Three patients had Candida infection, all of which were malnourished, had biliary atresia, and had been managed with prolonged antibiotics against obstinate ascending cholangitis. There were 14 symptomatic viral infections (1 herpes simplex virus, 1 herpes zoster virus, 5 cytomegalovirus [CMV], 6 EBV, and 1 EBV-associated LPS). Three of the five CMV infections appeared in patients whose graft was ABO-incompatible, who were managed with prophylactic OKT-3. Most of the viral infections (except 1 EBV-associated LPS) were minor and were treated successfully. The low incidence and successful treatment of CMV infection are related to the high compatibility and low incidence of allograft rejection in LRLT. Bacterial and fungal infections can be decreased by greater refinement of surgical technique and more aggressive preoperative management. Treatment of EBV infection is still an unsolved problem.

Adolescent↗

PubMed1994

Living related liver transplantation in children.

We reviewed 37 living related liver transplantations (LRLT) performed by our department during the last 27 months on children with end-stage liver disease. The patients were 15 boys and 22 girls aged 7 months to 15 years with biliary atresia (27), cryptogenic cirrhosis (3), Budd-Chiari syndrome (2), progressive intrahepatic cholestasis (2), protoporphyria (1), Wilson's disease (1), and fulminant hepatitis (1). The donors were 14 fathers and 23 mothers. Grafts were made from the left lateral segment (19), left lateral segment with partial S4 (11), left lobe (6), and right lobe (1). After graft harvesting all donors resumed normal liver function and normal life. The recipient underwent total hepatectomy with preservation of the inferior vena cava. FK506 and low-dose steroids were used for immunosuppression. The survival rate was 90% (27/30) in elective cases and 57% (4/7) in emergency cases. Six recipients had functioning grafts but died of extrahepatic complications. Hepatic vein stenosis occurred in 3 cases at 3 months after LRLT and was successfully treated by balloon dilatation. Portal vein stenosis occurred in 1 case at 8 months after LRLT and was also safely dilated. We incurred no hepatic artery thrombosis after introducing microsurgery techniques. Among 12 viral, 5 bacterial, and 3 fungal postoperative infections, 1 Candida pneumonia and 1 EBV-associated lymphoma were lethal. Three patients with ABO-blood group compatible grafts and one with an incompatible graft developed acute rejection, which was controlled in evey case by steroid bolus and/or increasing the dose of FK506. There were no definite episodes of rejection in ABO-identical cases. Children with moderate growth retardation (> or = -1.5 SD of normal growth) caught up in growth soon after LRLT, but those with severe retardation (<-1.5 SD) were slow to attain age-normal height. Appropriate timing, meticulous surgical procedures, and comprehensive management of complications are crucial for successful outcome with LRLT. LRLT is a promising option for alleviating the shortage of livers for pediatric transplantation and may be regarded as an independent modality to supplement cadaver donation.

Acute Disease↗

PubMed1994

Mutational analysis of the Sar1 protein, a small GTPase which is essential for vesicular transport from the endoplasmic reticulum.

SAR1 encodes a 21-kDa GTPase, which is required for vesicle formation from the endoplasmic reticulum in yeast. Although it belongs to the expanding small GTPase superfamily, there are interesting structural features that are unique to the Sar1 protein. We performed a site-directed mutational study to identify the amino acid residues that are essential for the Sar1p function. Among seven mutants we constructed, four are functionless by themselves, while two confer temperature sensitivity to cells. When the mutant proteins are overproduced in wild-type cells, all of these six show a dominant negative effect on cell growth. The replacement by serine of the only cysteine residue present in Sar1p caused no significant change in the growth phenotype. These findings are not only important for analyzing the mechanism of the Sar1p action in yeast, but will also be very useful for studying the function of Sar1p counterparts in higher eukaryotes.

Amino Acid Sequence↗

PubMed1994

[An epidemiologic research design using the Annual of the Pathological Autopsy Cases in Japan].

Epidemiologic research designs using the Annual of the Pathological Autopsy Cases in Japan (APAC hereinafter) are discussed in this paper. The APAC data base has been recommended for use in epidemiologic research. However, it has not often been utilized for such research, even though it covers all pathological autopsy cases in Japan, perhaps because of different sampling proportions of each disease and because of the dead control series in APAC. First, we present epidemiologic measures in using the APAC. We show that the data base can be treated as a case-control design and that the magnitude of the exposure effect should be estimated by an odds ratio. Next, selection bias and information bias in using the APAC are discussed. The independence of the control series from the exposure is important in the determination of the control disease. Because this design is based on internal comparison, non-differential misclassification should be stressed more than differential misclassification.

Autopsy↗

PubMed1994

Statistical methods for the beta-binomial model in teratology.

The beta-binomial model is widely used for analyzing teratological data involving littermates. Recent developments in statistical analyses of teratological data are briefly reviewed with emphasis on the model. For statistical inference of the parameters in the beta-binomial distribution, separation of the likelihood introduces an likelihood inference. This leads to reducing biases of estimators and also to improving accuracy of empirical significance levels of tests. Separate inference of the parameters can be conducted in a unified way.

Animals↗

PubMed1994

Audiometry database system using a local area network.

We linked several audiometers to a personal computer to implement a standard pure-tone audiometric database system using a local area network (LAN). The efficiency of data entry and retrieval was increased by taking advantage of a relational database. The following five programs were developed: automatic incorporation of hearing test data program, audiogram retrieval and display program, patient information incorporation program, data transmission program through LAN, and evaluation of results of tympanoplasty. Data obtained over ten years or more can be rapidly stored and retrieved in this system, making it easier to evaluate the patient's hearing after tympanoplasty.

Audiometry, Pure-Tone↗