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Biomedical subjects

Y Yamazaki

Publications and source records attributed to Y Yamazaki.

At least 235 records · Page 13Linked to original sources
PubMed1998

Interaction of the protonated Schiff base with the peptide backbone of valine 49 and the intervening water molecule in the N photointermediate of bacteriorhodopsin.

The effects of replacing Val49, Thr46, Asp96, and Phe219 in the cytoplasmic domain of bacteriorhodopsin on water O-H stretching vibrational bands and the amide I and imide II bands of the peptide backbone were examined in the M, N, and MN intermediates. This study is an extension of previous work on the L photointermediate [Yamazaki, Y., Tuzi, S., Saitô, H., Kandori, H., Needleman, R., Lanyi, J. K., and Maeda, A. (1996) Biochemistry 35, 4063-4068]. The O-H stretching bands at 3671 cm-1 in the M intermediate and at 3654 cm-1 in the N intermediate are shown to originate from the same water molecule. It is located in the region surrounded by the Schiff base, Val49, Thr46, and Phe219 in the M intermediate, and moves closer to Val49 in the M to N reaction. The peptide C-N bond between Val49 and Pro50 and the C=O bond of Val49 undergo perturbations upon formation of the N intermediate but not the M and N-like MN states in which the Schiff base is unprotonated. The carbonyl oxygen of Val49 is proposed to be the acceptor in H-bonding with the protonated Schiff base in the N intermediate. The results suggest that water molecules may be involved in this interaction in the cytoplasmic region, and may play a role in the accessibility change of the Schiff base in the L to M to N photocycle steps.

Bacteriorhodopsins↗
PubMed1998

Effects of imipramine and sertraline on protein kinase activity in rat frontal cortex.

Three-week administration of sertraline or imipramine to rats (10 mg/kg, intraperitoneally, twice a day) increased ex vivo cyclic AMP-dependent protein kinase activity in the soluble but not in the particulate fraction of the frontal cortex. However, cyclic AMP-dependent protein kinase activity was not affected in either fraction of the parietotemporal cortex and hippocampus. Neither antidepressant altered protein kinase C activity in the soluble and particulate fractions or Ca2+/calmodulin-dependent protein kinase II activity in the frontal cortex. Therefore, sertraline and imipramine both selectively enhance cyclic AMP-dependent protein kinase activity in the frontal cortex. This enhancement might be involved in their biochemical mechanisms.

1-Naphthylamine↗
PubMed1998

Comparison of biomechanical properties of the incisor periodontal ligament among different species.

BACKGROUND: The aim of this study was to obtain a more precise understanding of the mechanical properties of the periodontal ligament in continuously erupting incisors by comparing the shear stress-strain relations among teeth from four closely related species. METHODS: Four species of experimental animals (mice, hamsters, rats, and rabbits) were used. Transverse sections of the left mandibular incisors were cut from the incisal, middle, and basal regions of each incisor. The tooth was pushed out of the alveolar bone in an extrusive direction at 5 mm/min using a materials testing machine. The maximum shear stress, maximum shear strain, tangent modulus, and failure strain energy density were estimated from the resulting stress-strain curve. Polarized light microscopic observations of collagen fibers were also made. RESULTS: All the biomechanical measures tended to decrease from the incisal toward the basal regions in all species. There were large species differences, especially in the incisal region, with the greatest maximum shear stress and failure strain energy density in hamsters. The greatest tangent modulus and the smallest maximum shear strain were observed in mice. The birefringent fiber architectures of the periodontal ligaments in the four species appeared to be similarly organized; the incisal periodontal ligament appeared to have more organized and thicker collagen fibres than did the middle and basal ligaments in the four species. CONCLUSIONS: These results suggest that the regional differences in the biomechanical properties of the periodontal ligament depend upon the developmental stages of the periodontal collagen fibers that may be related to the general arrangement, diameters, and densities of the collagen fiber bundles and the fiber insertions into the alveolar bone and cementum. The species differences in the biomechanical properties may be due to differences in the width of the periodontal ligament and the waviness as well as the strength and stiffness of the periodontal collagen fibers.

Animals↗
PubMed1998

The long-term survival rates of patients after repair of abdominal aortic aneurysms.

This study was undertaken to examine the long-term survival rates of patients following abdominal aortic aneurysm (AAA) repair in comparison with an age-matched normal population, and to determine by multivariate analysis the factors influencing long-term survival. Of 125 patients who underwent AAA repair prior to July 1986, 13 died during hospitalization. Of these 13 patients, 6 who suffered aneurysmal rupture all died within 30 days. The survival rate of patients with ruptured aortic aneurysms was significantly lower than that of those with nonruptured aneurysms. Of the 112 patients surviving hospitalization, 85 died within 0.48 to 24 years after their operation. The long-term survival rate of patients who had suffered a preoperative cardiovascular event was significantly lower than that of those who had not suffered a preoperative cardiovascular event. The actual survival rate was significantly lower than the expected survival rate. According to a multivariate analysis, the significant predictors of late survival were age, aneurysmal rupture, and chronic renal failure in all the patients, and age, chronic renal failure, and pre- and postoperative cardiovascular events in patients who did not die in hospital. These findings indicate the importance of improving immediate perioperative management of ruptured AAA and that cardiovascular events should be prevented, or treated during long-term follow-up.

Adult↗
PubMed1998

[Study on surgical treatment for lung cancer associated with giant bullous disease].

Five patients of primary lung cancer with giant bullous disease underwent surgery from April 1985 to December 1995. All patients were male and heavy smokers, and the median age was 50 years. The location of the tumor was in the right upper lobe in four patients and in the left upper lobe in the other. Three patients were treated by lobectomy and two by sleeve lobectomy. Histological examination showed large cell carcinoma in four patients and poorly-differentiated adenocarcinoma in the other. The pathological stage was I in three. IIIA in one, and IV in the other. Two of three in stage I have survived for more than 6 years postopertively without recurrence, and the other died of brain metastasis. The stage IIIA case and the IV case died 3 years and one year postoperatively, respectively. The clinical features of lung cancer associated with giant bullous disease was discussed by reviewing 33 patients reported in Japan, including our patients. In 13 patients, lung cancer and bullous disease were diagnosed simultaneously (group A), and in 20 patients, bullous disease were diagnosed prior to the appearance of an abnormal shadow due to lung cancer (group B). The patients in group B had a tendency to be diagnosed at an earlier stage of lung cancer than the patients in group A. In the patients of stage I, the 5-year survival rate was 78.6%, however, in the patients of more than stage IIIA, 3-year survival rate was 26.5% and the 5-year survival rate was 0%. Significant differences in the survival curves were demonstrated between the cases with stage I and the cases with more than stage IIIA. In conclusion, in order to improve the prognosis of lung cancer with giant bullous disease, it is considered to be important to detect giant bulla prior to lung cancer, and when a case of bullous disease is found, periodical follow-up must be done to find early stage lung cancer.

Adenocarcinoma↗
PubMed1998

[A resected case of malignant peripheral nerve sheath tumor (MPNST) necessary to distinguish from Askin tumor].

We have treated a patient with malignant peripheral nerve sheath tumor (MPNST) for 7 years by interdisciplinary therapy. The diagnosis and treatment are reported with the clinical course so far. A 20-year-old man underwent surgical resection of a tumor on the left side of the chest in 1990, and a diagnosis of Askin tumor was made. In 1993, the disease recurred in the left axilla and was surgically resected. The surgical specimen was investigated histologically, and a diagnosis of MPNST was made instead of Askin tumor. Recently, a tumor began to grow in the left pleural cavity and was surgical resected. The tumor tissue contained both cells with oval and long spindle nuclei, which were intermingled with each other. Immunohistochemically, the tumor cells were positive for vimentin and some of them were positive for S100 protein. Because electron microscopy showed cytoplasmic processes on the tumor cell and basal lamina-like structures, a diagnosis of recurrent MPNST was made. Because this lesion resembled Askin tumor in its clinical manifestations and histological characteristics, differential diagnosis from Askin tumor was necessary. When a malignant soft tissue tumor arising from the mediastinum or chest walls is detected, immunohistochemical and electron microscopic studies should be performed. The diagnosis should be based on the overall findings including the location and clinical data.

Adult↗
PubMed1998

Reconstruction of thoracic wall defects after tumor resection using a polytetrafluoroethylene soft tissue (Gore-Tex) patch.

BACKGROUND: Recently, there have been a few reports recommending use of a 2 mm thick polytetrafluoroethylene soft tissue (Gore-Tex) patch for repair of thoracic wall defects. The potential role of these Gore-Tex patches was examined. METHODS: Five patients underwent chest wall tumor resection with thoracic wall reconstruction using a Gore-Tex patch (2 mm). We present a review of the complications experienced by five patients with Gore-Tex patches, as well as a review of the literature. RESULTS: Functionally and cosmetically, satisfactory results were obtained for 5 patients with Gore-Tex patch. There were no cases of infectious complications. However, we experienced one case of a flail chest postoperatively, in which reconstruction with two Gore-Tex patches of 30 x 15 cm, and 3 days of mechanical ventilation and chest wall support was needed. CONCLUSION: Our experience with Gore-Tex patches has been positive, and we recommend patch closure for thoracic wall defects.

Adolescent↗
PubMed1998

[The usefulness of thoracoscopic surgery for pleuritis carcinomatosa].

We performed thoracoscopic surgery for pleuritis carcinomatosa, in which re-expansion of the collapsed lung was impossible, by employing tube thoracostomy. One of the treatments used for pleuritis carcinomatosa was drainage of the pleural effusion followed by re-expansion of the collapsed lung. The decortication and biopsy of the pleura and the pleural effusion drainage with the thoracoscopic procedure were performed, allowing control of the pleural effusion and re-expansion of the collapsed lung to be accomplished. We conclude that thoracoscopic surgery is useful for the thoracic treatment of pleuritis carcinomatosa.

Adenocarcinoma, Papillary↗
PubMed1998

Mycobacterium avium-intracellulare pulmonary infection in patients without known predisposing lung disease.

We tried to characterize the clinical features and findings on chest high resolution computed tomography (HRCT) of patients with Mycobacterium avium-intracellulare (MAI) pulmonary infection without known predisposing lung disease and with no immunodeficiency. We also aimed to clarify the small airway and alveolar inflammation using bronchoalveolar lavage (BAL) from the affected regions. MAI infection was diagnosed in 53 patients from respiratory samples, including sputum and materials obtained using a fiberoptic bronchoscope. None had a predisposing lung disease or immunodeficiency, as assessed by medical history, routine laboratory data, and previously normal chest radiographs and/or CT scans. The mean age of the 53 patients was 60 +/- 11 years, and 48 were nonsmoking females. They had few respiratory symptoms, although 42% had chronic paranasal sinusitis. Chest HRCT findings showed centrilobular small nodules and ectasia of small bronchi and/or bronchioles located mainly in segment (S) 2, 3, 4, and 5. S1, which is usually affected by pulmonary tuberculosis, was completely free of these opacities. The BAL study revealed that the predominant cells were activated T lymphocytes and neutrophils. The CD4+/CD8+ ratio increased significantly. Bacteriology was negative for other bacteria and fungi. Although our patients did not present with distinct respiratory symptoms, the regions affected by MAI showed a chronic inflammation of mainly neutrophils and activated T lymphocytes. The presence of chronic sinusitis may be merely coincidental. However, its high prevalence and the finding of bronchiectasis in chest HRCT raise the question of whether silent bronchiectasis may be a predisposition.

Aged↗
PubMed1998

Novel approaches to prodrugs of anticancer diaminodichloroplatinum(II) complexes activated by stereoselective enzymatic ester hydrolysis.

A series of dichloro(ethylenediamine)-type platinum complexes bearing ester-, amide- and ether-bonded alkyl straight chains (C2-C18) was prepared as a model for the prodrug of cis-diamminedichloroplatinum (CDDP). Evaluation of cytotoxic activity of the complexes against the S-180 cell line proved that their enzymatic hydrolysis in the cells lowered the permeability to the cell membranes resulting in an increase of pharmacological activity. Optically active isomers of dichloro(N-2(2-phenylpropanoyloxy)ethyl)-2,3-diaminopropanamide )platinum(II) were prepared. They were re-activated stereoselectively, and a tenfold difference in activity was observed based on the differences in chiral discrimination by enzymes.

Animals↗
PubMed1998

A novel variant of acute myelomonocytic leukemia carrying t(3;12)(q26;p13) with characteristics of 3q21q26 syndrome.

Chromosomal translocation often results in aberrant activation of the genes with oncogenic potential and, thus, plays an important role in leukemogenesis. We report a unique case of acute myelomonocytic leukemia carrying a rare reciprocal translocation, t(3;12)(q26;p13). This patient displayed typical clinical features of 3q21q26 syndrome such as abnormal thrombopoiesis and rapid disease progression. Blastic cells from the patient strongly expressed the EVI1 gene, which is located on 3q26 and is normally suppressed in bone marrow cells. Expression of the TEL gene, located on 12p13, was also observed, but fusion transcript between two genes was not found. No structural alterations of the EVI1 and TEL genes were detected by Southern blot and PCR analyses. We reviewed previous literature and found 10 other cases with t(3;12)(q26;p13). These patients comprise a unique disease group with features including dyshematopoiesis and poor prognosis. However, characteristics related to 3q21q26 syndrome were observed only in the present case. Further investigation is required to elucidate the molecular basis of this particular entity.

Chromosomes, Human, Pair 12↗
PubMed1998

Hemolysis caused by CMV infection in a pregnant woman with silent elliptocytosis.

Elliptocytosis is reported to occur in at least 1 per 5000 individuals, but most cases are heterozygous and do not show clinical hemolysis. Healthy individuals with silent elliptocytosis, however, may suddenly have an episode of hemolysis [1]. Here we report a woman in the third trimester of pregnancy who suffered from cytomegalovirus (CMV) infection with hemolysis. Scanning electron microscopy showed that half of her red blood cells were oval, and protein analysis revealed a 50% reduction of protein 4.1. We discuss the role of CMV infection and pregnancy in the onset of hemolysis in a patient with otherwise silent elliptocytosis.

Adult↗
PubMed1998

Proinflammatory cytokines detectable in synovial fluids from patients with temporomandibular disorders.

OBJECTIVE: To measure the levels of the proinflammatory cytokines, interleukin (IL)-1 beta, IL-6, tumor necrosis factor- (TNF) alpha, IL-8, and interferon- (IFN) gamma in synovial fluid samples taken from patients with temporomandibular disorders (TMD). STUDY DESIGN: We studied 6 asymptomatic volunteers and 51 patients with TMD. The IL-1 beta, IL-6, TNF-alpha, IL-8, and IFN-gamma levels in temporomandibular joint synovial fluid were measured using enzyme-linked immunosorbent assay. RESULTS: Measurable level of at least one cytokine in the synovial fluid was found in 40 (64.5%) of 62 joints in the patients: IL-1 beta and IFN-gamma were each detected in 18 (29.0%) of 62 joints; IL-6 in 13 (21.0%) of 62 joints; IL-8 in 11 (19.3%) of 57 joints; and TNF-alpha in only 5 (8.1%) of 62 joints. None of these cytokines was detectable in the synovial fluid in the control group. Furthermore, there was a strong correlation between the detection of IL-1 beta and pain in the joint area. CONCLUSIONS: These data clearly demonstrate increased levels of several proinflammatory cytokines in certain patients with TMD and suggest that these cytokines may play a role in the pathogenesis of synovitis and degenerative changes of the cartilaginous tissue and bone of the temporomandibular joint.

Adolescent↗
PubMed1998

Species differences in the distribution of beta-adrenoceptor subtypes in bladder smooth muscle.

1. The beta-adrenoceptor (beta-AR) subtypes mediating relaxation of the rabbit, rat and canine detrusors were subjected to functional investigation using selective beta-AR agonists and antagonists. 2. In all three species, isoprenaline, noradrenaline and adrenaline each produced a concentration-dependent relaxation of the detrusor. The rank order for their relaxing potency was isoprenaline>adrenaline>noradrenaline in rabbits and rats, but isoprenaline>noradrenaline>adrenaline in dogs. 3. Dobutamine did not produce relaxation of the detrusors at concentrations that are selective for beta1-AR. The selective beta2-AR agonist, procaterol, had a more potent relaxing effect on rabbit and rat detrusors than on the canine detrusor. CGP-12177A, a selective beta3-AR agonist, was more effective in the rabbit than in the other two species. On the other hand, the relaxing effect of another beta3-AR agonist, CL316243, was more pronounced in dogs and rats than in rabbits. 4. CGP-20712A (10(-9) to 10(-7) M), a selective beta1-AR antagonist, caused a slight rightward shift of the concentration-relaxation response curve for isoprenaline in the canine detrusor (pA2 9.41), but not in the rabbit and rat detrusors. ICI-118,551, a selective beta2-AR antagonist, antagonized the isoprenaline-induced relaxation in rabbits (pA2 9.45) and rats (pA2 9.05), but not in dogs. Bupranolol, a non-selective beta-AR antagonist, caused a rightward shift of the concentration-relaxation curve for isoprenaline in the rabbit (pA2 9.32) and rat (pA2 8.98). However, higher concentrations (3 x 10(-8) to 10(-5) M) were needed to induce a rightward shift of the curve for isoprenaline in the dog (pA2 8.19) than in the other two species. 5. We have confirmed that the distribution of beta-AR subtypes in the detrusor muscle varies significantly from species to species and we provide here the first evidence of the presence of beta3-AR in the detrusor. It is suggested that the relaxation induced by adrenoceptor agonists in urinary bladder smooth muscle may be mediated mainly via beta2-AR in rabbits, via both beta2- and beta3-AR in rats, but mainly via beta3-AR in dogs.

Adrenergic beta-Agonists↗