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Biomedical subjects

J Yamamoto

Publications and source records attributed to J Yamamoto.

At least 91 records · Page 5Linked to original sources
PubMed1999

Acquisition of glutamine synthetase expression in human hepatocarcinogenesis: relation to disease recurrence and possible regulation by ubiquitin-dependent proteolysis.

BACKGROUND: The authors previously reported increased ubiquitin (Ub) immunoreactivity in hepatocellular carcinomas (HCCs) and suggested a possible correlation between changes in ubiquitinated protein levels and multistep hepatocarcinogenesis. The current study was performed to identify one of these ubiquitinated proteins (42 kDa) and to analyze the clinical significance of its accumulation. METHODS: The protein was purified using two-dimensional gel electrophoresis and identified by amino acid sequence analysis. The authors studied the expression of this protein in 101 HCCs and 23 precancerous lesions by immunohistochemical methods and in 26 HCCs by immunoblot analysis. A survival analysis was performed on patients with advanced HCC using the Kaplan-Meier method with approximate chi-square statistics for the log rank test. RESULTS: The target protein for ubiquitination was identified as glutamine synthetase (GS). Accumulation of GS was found in 19 of 49 advanced HCCs (38.8%) by immunohistochemical methods and in 9 of 16 (56.3%) by immunoblot analysis, whereas the frequency was much lower in early HCCs (12.9% and 33.3%, respectively) and precancerous lesions (4.3% by immunostaining). In the Ub immunoblot analysis of strongly GS positive specimens, an intense 42-kDa ubiquitinated band was observed. Nine of 21 (42.9%) nodule-in-nodule type HCCs showed a GS positive, high-grade component within a GS negative, low-grade component, indicating the acquisition of GS expression during progression. Among 23 patients with a single advanced HCC nodule, the relapse free survival time was significantly shorter in the GS positive group than in the GS negative group. CONCLUSIONS: The results of this study demonstrate the acquisition of GS expression during hepatocarcinogenesis and the possible regulation of GS enzyme activity by a Ub-dependent proteolytic system. Moreover, GS might play a significant role in promoting the metastatic potential of HCC.

Amino Acid Sequence↗
PubMed1999

Myotonic dystrophy associated with QT prolongation and torsade de pointes.

A rare case of myotonic dystrophy (MD) with congestive heart failure, associated with QT prolongation and torsade de pointes (TdP) is reported. A 53-year-old woman was admitted to the hospital because of congestive heart failure. Electrocardiograph (ECG) showed first-degree atrioventricular block and QT prolongation. During hospitalization, TdP appeared but returned to sinus rhythm spontaneously. As the patient had quadriplegia, a myopathic face, cataracts, diabetes mellitus, and an increased number of cytosine-thymineguanine (CTG) repeats (760 repeats), she was diagnosed as having MD. Electrocardiographic analysis of her family also revealed abnormal QT(U) prolongation in her daughter and brother who both had MD, while ECG findings of other family members without MD were normal. Thus, the presence of QT(U) prolongation was associated with MD in this family.

Cardiotonic Agents↗
PubMed1999

Anterior transhepatic approach for isolated resection of the caudate lobe of the liver.

We have devised a new technique for isolated caudate lobe resection in which we access the caudate lobe by separating the liver parenchyma along the interlobar plane. The safety and radicality of the procedure were evaluated in five patients: four with hepatocellular carcinoma (HCC) and one with metastatic rectal cancer. All of the tumors were located mainly in the paracaval portion of the caudate lobe. The patients with HCC (three of four) underwent an anatomic caudate lobe resection by identification of the right margin of the caudate lobe. Two patients required red blood cell transfusion, and one showed bile leakage after surgery. All of the patients are alive without recurrence more than 4 years after surgery, except one with rectal carcinoma who developed lung metastases. The anterior transhepatic approach is a safe and potentially curative surgical option for a tumor in the paracaval portion of the caudate lobe.

Aged↗
PubMed1999

Repeat liver resection for recurrent colorectal liver metastases.

BACKGROUND: This study aimed to delineate the role of surgery for recurrent colorectal cancer in the liver and to identify prognosticators for better patient selection and outcome. METHODS: Data from 90 repeat hepatectomies (second = 75; third = 12; fourth = 3) for recurrent colorectal cancer were collected. RESULTS: After the second hepatectomy, the 3-and 5-year survival rates were 48% and 31%, respectively. Twenty-seven percent (20 of 75) of patients are alive without recurrence after a median follow-up of 27 months, and 9 survived more than 5 years. Four or more tumors, positive regional lymph node metastases, concomitant extrahepatic disease, and residual tumor were independent poor prognostic factors after the second hepatectomy. CONCLUSIONS: Repeat hepatectomy should be applied for recurrent colorectal cancer, when curative removal of the tumor is possible, although the benefit from treatment was limited in a patient with regional lymph node metastases, 4 or more metastases, or extrahepatic disease.

Adult↗
PubMed1999

Degranulation of eosinophils mediated by intercellular adhesion molecule-1 and its ligands is involved in adhesion molecule expression on endothelial cells-selective induction of VCAM-1.

BACKGROUND: Adhesion molecules and eosinophils may play an important role in the pathogenesis of allergic inflammatory reactions. OBJECTIVE: We attempted to clarify eosinophil activation, such as degranulation, by signaling through adhesion molecule and to determine whether degranulation is involved in adhesion molecule expression on endothelial cells. METHODS: Eosinophils were cultured with or without recombinant soluble intercellular adhesion molecule-1 (ICAM-1), and the levels of eosinophil cationic protein and eosinophil-derived neurotoxin were determined. The influence of these eosinophil granule proteins or supernatant from eosinophil cultured with ICAM-1 on the expression of ICAM-1 or vascular cell adhesion molecule-1 (VCAM-1) on endothelial cells was also examined by flow-cytometric analysis. RESULTS: Supernatant levels of eosinophil granule protein were significantly increased by culture for 4 hourss or 16 hours with recombinant soluble ICAM-1, suggesting degranulation by adherence to ICAM-1. Both granule proteins and the supernatants of eosinophils cultured with recombinant soluble ICAM-1 induced expression of ICAM-1 and VCAM-1 on endothelial cells, with the latter showing a more prominant increase. CONCLUSION: Degranulation mediated through adherence to endothelial cells by ICAM-1 and its ligands may be involved in the expression of adhesion molecules, such as ICAM-1 or VCAM-1, on these cells. Our finding of the selective induction of VCAM-1 expression suggests that eosinophil adherence to endothelial cells, even if it is because of ICAM-1, may be involved in selective eosinophil recruitment and accumulation at sites of allergic inflammation.

Cell Adhesion Molecules↗
PubMed1999

Cognitive behavioral therapy of minor depressive symptoms in elderly Chinese Americans: a pilot study.

There is a high prevalence of suicide among elderly Chinese, and particularly among elderly Chinese women in Mainland China with a prevalence of 19.6 per hundred thousand. Since Chinese individuals may much more highly value education, a cognitive-behavioral package originated by Ricardo Munoz, Ph.D. was adapted for Chinese American subjects. The material was videotaped in eight sessions, approximately 25 minutes in length, to be shown to community subjects who were at least 40 years and over. In addition, a videotape of muscular relaxation techniques was made. A manual written in Chinese about the content of each class, was given to each subject when he/she attended. The experimental group showed significant improvement in the scores in the Hamilton Depression Scale, including the Somatic Subscale in the Hamilton Anxiety Scale. There was no significant improvement in the control group on any of the measures. Thus the study suggests the efficacy of psychoeducational classes in reducing symptoms of depression in non-patient community elderly. Other studies are being conducted among Korean Americans and Japanese Americans in the United States, and also in the Orient among Japanese elderly.

Aged↗
PubMed1999

Factors influencing survival of patients undergoing hepatectomy for colorectal metastases.

BACKGROUND: The extent of surgical margin is still a matter of controversy with regard to outcome after liver resection for metastatic disease. The aim of this study was to clarify the significant prognostic factors after hepatectomy for colorectal metastases, with special reference to the surgical margin. METHODS: Ninety-six patients who underwent initial hepatic resection for liver metastases from colorectal cancer between 1992 and 1994 were studied. RESULTS: Overall 1-, 3- and 5-year survival rates were 94, 61 and 51 per cent respectively. All of the independent factors associated with poor prognosis after hepatic resection were tumour-related factors, such as the number of tumours (four or more), presence of portal vein invasion, hepatic vein invasion and absence of a fibrous pseudocapsule. A positive resection margin was not an independent prognostic factor, because of its strong relationship with the number of tumours resected. CONCLUSION: A generous surgical margin is not essential for curative hepatic resection, although positive surgical margins should be avoided. New potential risk factors which affect survival, such as the presence of portal vein or hepatic vein invasion and the absence of a pseudocapsule, may be helpful for defining the indications for postoperative adjuvant treatment.

Adult↗
PubMed1999

The differential effects of aspirin on platelets, leucocytes and vascular endothelium in an in vivo model of thrombus formation.

Unanswered questions remain with regard to the therapeutic use of aspirin and the selective inhibition of thromboxane A2 and prostacyclin in platelets and endothelial cells. In the present study, the effects of aspirin on platelets and endothelial cells in vivo were examined using a helium-neon (He-Ne) laser-induced thrombosis model. Single intravenous injections of aspirin at concentrations of more than 0.5 mg/kg body weight mediated a dose dependent inhibition of thrombus formation in arterioles but not in venules. This antithrombotic effect was optimum after 15 min and declined after 90 min. Potent antithrombotic activity in arterioles was manifest at doses of 2.5 mg/kg to 50 mg/kg, and initial inhibition of thrombogenesis in vivo was most pronounced at high doses. Oral aspirin also inhibited thrombus formation in arterioles but not in venules, although the antithrombotic effects were delayed and prolonged. Maximum inhibition of ex vivo, collagen induced platelet aggregation by aspirin was observed approximately 180 min after intravenous injection. The results demonstrated that, although aspirin might have differential effects on platelets and endothelial cells, potent antithrombotic activity was manifest in arterioles at all concentrations. The findings suggest that the concept of the aspirin dilemma might be ignored for therapeutic purposes in many clinical circumstances. The antithrombotic effects of aspirin were unchanged in granulocyte-depleted animals, indicating that leucocyte-related mechanisms including neutrophil superoxide anion production did not modulate the potency of aspirin in this model.

Animals↗
PubMed1999

Effects of voluntary exercise and L-arginine on thrombogenesis and microcirculation in stroke-prone spontaneously hypertensive rats.

1. The preventive effects of exercise and L-arginine intake on hypertension and thrombosis in stroke-prone spontaneously hypertensive rats (SHRSP) were studied. 2. Stroke-prone spontaneously hypertensive rats were divided into three groups: (i) the control, sedentary group; (ii) the exercise group, which was allowed to run voluntarily on running wheels; and (iii) the L-arginine intake group, which was given 2.25% L-arginine solution for 8 weeks from 4 to 12 weeks of age. In the control group, one rat died from stroke and symptoms of stroke were observed in the remaining animals. Similar symptoms were recorded in one rat of the exercise group, but not in the L-arginine group. 3. Blood pressure increased in the control group and this increase was suppressed significantly in the exercise and L-arginine groups. Thrombotic potential in cerebral vessels was the lowest at 4 weeks in all groups and was increased significantly at 12 weeks in the control group, but not in the exercise and L-arginine groups. Plasma concentrations of NO2/NO3 were lower in all animals at 12 weeks compared with those at 4 weeks. This reduction was significantly less marked in the L-arginine group. Cerebral arterioles in control rats at 12 weeks of age were significantly smaller in diameter than those at 4 weeks and these changes were less pronounced in the exercise and L-arginine groups. 4. The results provide clear evidence for the beneficial effects of L-arginine intake and voluntary exercise in mechanisms related to hypertension, thrombosis and stroke.

Animals↗
PubMed1999

Effect of temperature and mechanical strain on gastric epithelial cell line GSM06 wound restoration in vitro.

BACKGROUND: The influence of the degree of cell differentiation and of physical stimulation on gastric mucosal wound healing is not completely understood. METHODS: A gastric mucosal cell line, GSM06, derived from the gastric mucosal cells of transgenic mice harbouring the simian virus 40 large T antigen, was cultured at 33 degrees C to make a confluent cell sheet. Artificial wounds of constant size were created. Wound healing was monitored at different temperatures (33, 37 and 39 degrees C), which altered the degree of differentiation. Cell proliferation was detected by bromodeoxyuridine staining. Mechanical strain was applied to adherent GSM06 cells after wounding in order to increase their length by an average of 5 or 10% at 5 cycles/min for 60 h. Repair of the wound was monitored every 12 h. RESULTS: Differentiated gastric epithelial cells showed a higher speed of migration. The number of proliferating cells around the wound was greatest at 33 degrees C and barely detectable at 39 degrees C. Under conditions of mechanical strain, the migration speed of differentiated cells (at 39 degrees C) slowed in a strain strength-dependent manner. CONCLUSIONS: It is suggested that cell differentiation status and physical stimulants might play a role in gastric wound healing in vivo by modifying cellular migration.

Animals↗
PubMed1999

A shear-induced in vitro platelet function test can assess clinically relevant anti-thrombotic effects.

Morphological features of haemostatic plugs formed in vitro under high shear forces were investigated. Electron microscopy confirmed the relevance of such haemostatic plug to a platelet-rich arterial thrombus, which is formed in vivo . In rat blood samples, the effects of anticoagulants and various antiplatelet agents on platelet reactivity (rate of haemostatic plug formation) and subsequent coagulation of the flowing blood were investigated. Haemostasis did not occur in citrated blood, and heparin greatly inhibited the shear-induced platelet reaction. Aspirin (1 mM), a thromboxane A(2) receptor antagonist (5 microM), a stable prostacyclin (0.55 nM), a stable prostaglandin E(1) (141 nM) and a phosphodiesterase inhibitor (100 microM) were tested. All these agents exerted significant inhibitory effect on shear-induced platelet reaction, including the inhibition of the very first phase of platelet plug formation, due to aggregation of shear-activated platelets. Except for the phosphodiesterase inhibitor, which prolonged clotting time, none of the above agents affected dynamic coagulation. These results suggest that the employed in vitro shear-induced thrombosis/haemostasis test can reveal in vivo the antithrombotic effect of various agents independently of their mechanism of action.

Journal Article↗
PubMed1999

Improved surgical results for hilar cholangiocarcinoma with procedures including major hepatic resection.

OBJECTIVE: To evaluate the long-term outcome of aggressive surgery incorporating hepatic resection and systematic nodal dissection for advanced carcinoma involving the hepatic hilus. SUMMARY BACKGROUND DATA: Few long-term results are available regarding radical surgery incorporating major hepatectomy and nodal dissection. METHODS: A retrospective analysis was undertaken in 107 patients with carcinoma involving the hepatic hilus treated between 1980 and 1997. Resectional surgery was performed in 65 patients, 52 of whom underwent major hepatectomies. The effects of clinical and pathologic factors were assessed by univariate and multivariate analyses. RESULTS: Sixty percent of the patients with resectional surgery had stage IVA or IVB disease, and 92.3% of them underwent major hepatectomies. No in-hospital deaths were encountered in the 35 most recent resections, whereas there were six deaths in the early period. Resectional surgery was associated with a survival benefit, especially when resection margins were free from cancerous infiltration. The estimated 5-year survival rate after resection, including all deaths, was 34.8%; this was 51.6% when the margins were clear. Nodal involvement was documented in 44.6% of the resections. However, patients with metastases limited to the regional nodes showed a survival rate similar to that in patients without nodal involvement. Significant predictive factors for survival after resection were extension to the gallbladder, nodal status, resectional margins, histologic type, and gender. CONCLUSIONS: The combination of major hepatectomy with systematic nodal dissection gave a good chance of prolonged survival for patients with carcinoma involving the hepatic hilus, even when the disease was advanced. Less-extensive procedures were also beneficial for less-advanced disease if clear resectional margins were secured.

Adult↗
PubMed1999

Electromechanical Fredericks effects in nematic gels.

The solid nematic equivalent of the Fredericks transition is found to depend on a critical field rather than a critical voltage as in the classical case. This arises because director anchoring is principally to the solid rubbery matrix of the nematic gel rather than to the sample surfaces. Moreover, above the threshold field, we find a competition between quartic (soft) and conventional harmonic elasticity which dictates the director response. By including a small degree of initial director misorientation, the calculated field variation of optical anisotropy agrees well with the conoscopy measurements of Chang et al. [Phys. Rev. E 56, 595 (1997)] of the electro-optical response of nematic gels.

Journal Article↗
PubMed1999

Theiler's murine encephalomyelitis virus (TMEV) subgroup strain-specific infection in neural and non-neural cell lines.

GDVII subgroup strains of Theiler's murine encephalomyelitis virus (TMEV) are highly virulent and produce acute polioencephalomyelitis in mice. Neither viral persistence nor demyelination is demonstrated in the few surviving mice. In contrast, DA subgroup strains are less virulent and establish a persistent central nervous system infection which results in demyelinating disease. We previously reported a subgroup-specific infection in a macrophage-like cell line, J774-1 cells; i.e., GDVII strain does not replicate in J774-1 cells, whereas the DA strain actively replicates in these cells. In addition, this subgroup-specific virus growth is shown to be related to the presence of L* protein, a 17 kDa protein translated out-of-frame of the viral polyprotein from an AUG located 13 nucleotides downstream from the polyprotein's AUG. The present paper demonstrated that this subgroup-specific infection is observed in murine monocyte/macrophage lineage cell lines, but not in other murine cell lines including neural cells. An RNase protection assay also suggested that L* protein-related virus growth is regulated at the step of viral RNA replication. As macrophages are reported to be the major cell harboring virus during the chronic demyelinating stage, the activity of L* protein with respect to virus growth in macrophages may be a key factor in clarifying the mechanism(s) of TMEV persistence, which is probably a trigger to spinal cord demyelination.

Animals↗
PubMed1999

Assessment of myometrial invasion at the invasion site of an endometrial carcinoma by ultrasonography along with an intrauterine catheter.

OBJECTIVES: To evaluate by transvaginal ultrasonography (TVU) the thickness of the intact myometrium at the presumed tumor-origin site and to establish criteria for a half myometrial invasion. METHODS: A total of 19 successive patients with endometrial cancer who were treated between January 1, 1997, and January 31, 1998, participated in this study. TVU mode B with and without the use of an intrauterine silicon catheter was performed. RESULTS: Using a catheter, the origin site was correctly detected in 15 cases (79%). The best criterion for half myometrial invasion was a 6-mm thickness of the intact myometrium at the origin site. The sensitivity/specificity/accuracy of TVU with the use of a catheter in cases with the correct estimated origin site, were 1.00/0.67/0.86 for myometrial invasion < 1/2, and 0.67/1.00/0.86 for myometrial invasion > or = 1/2. CONCLUSION: It is of value to use 6-mm as the criterion for the thickness of the intact myometrium at the estimated tumor-origin site in connection with TVU with the use of a catheter for preoperatively assessing half myometrial invasion.

Adult↗
PubMed1999

Eye disease in a patient with rheumatoid arthritis.

We report the case of a 40-year-old woman with diffuse uveitis, sensorineural hearing loss and cerebrospinal fluid pleocytosis as features of Vogt-Koyanagi-Harada syndrome who developed symmetric polyarthritis and stiffness of small and large joints, in addition to rheumatoid arthritis. Although their target tissues are distinct, both diseases have a possible autoimmune origin strongly associated with HLA-DRB4.

Adult↗
PubMed1999

Norepinephrine, but not epinephrine, enhances platelet reactivity and coagulation after exercise in humans.

The effects of exercise and catecholamines on platelet reactivity or coagulation and fibrinolysis appear to be inconsistent. This may be partly due to the methods employed in previous studies. In the present study, we investigated the effects of acute aerobic exercise and catecholamines on the thrombotic status by a novel in vitro method, shear-induced hemostatic plug formation (hemostatometry), using nonanticoagulated (native) blood. Aerobic exercise (60% maximal O2 consumption) was performed by healthy male volunteers for 20 min, and the effect on platelet reactivity and coagulation was assessed by performing hemostatometry before and immediately after exercise. Exercise significantly increased shear-induced platelet reactivity, coagulation, and catecholamine levels. The effect of catecholamines on platelet reactivity and coagulation was assessed in vitro by adding catecholamines to blood collected in the resting state. The main findings of the present study are that elevation of circulating norepinephrine at levels that are attained during exercise causes platelet hyperreactivity and a platelet-mediated enhanced coagulation. This may be a mechanism of an association of aerobic exercise with thrombotic risk.

Adult↗