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Biomedical subjects

T Kamata

Publications and source records attributed to T Kamata.

At least 109 records · Page 6Linked to original sources
PubMed1994

Expression of a blood group B antigen-related glycoepitope in human dorsal root ganglion cells.

Carbohydrate epitopes of glycoconjugates are expressed on sensory neurons of dorsal root ganglion (DRG). A possible role of antibodies directed at carbohydrate determinants of the glycoconjugates has been suggested in some patients with sensory neuropathy. We investigated expression of blood group antigen-related epitopes in human DRG immunohistochemically using monoclonal antibodies to A, B, and H antigens. A blood group B determinant [Gal alpha 1-3(Fuc alpha 1-2)Gal beta-]-related glycoepitope was demonstrated in the neurons and surrounding satellite cells of DRG obtained from subjects with any ABO blood group phenotype. The treatment with trypsin or chloroform/methanol prior to the immunostaining suggested that the glycoconjugate exhibiting the blood group B determinant-related epitope consisted mainly of glycoprotein and included glycolipid. The glycoconjugates with the blood group B determinant-related epitope may play a role in the physiological function and pathophysiology of human DRG neurons.

ABO Blood-Group System↗
PubMed1994

Cerebral ischemic attack caused by postprandial hypotension.

BACKGROUND: Food ingestion sometimes induces systemic hypotension (postprandial hypotension). Although the possibility of stroke occurring postprandially has been suggested, no cases have been reported until now. CASE DESCRIPTION: A 78-year-old man experienced repeated transient ischemic attacks after almost every ingestion of food and showed orthostatic and postprandial hypotension. An angiogram revealed occlusion of his left carotid artery and stenosis of his right middle cerebral artery. CONCLUSIONS: Postprandial as well as orthostatic hypotension can be a risk factor for stroke in patients with severe occlusive cerebrovascular disease.

Aged↗
PubMed1994

Toxic epidermal necrolysis with tracheobronchial and pulmonary complications.

A 55-year-old man developed multiple erythematous skin lesions after surgery for acoustic neurinoma. Necrosis and detachment of the epidermis developed and a diagnosis of toxic epidermal necrolysis (TEN) was made. Progressive dyspnea was evident two days after the onset of the skin lesions. Chest X-ray revealed diffuse interstitial shadows in both lung fields. On bronchoscopic examination, erosion, vesicle formation, necrosis and desquamation of the epidermis were seen in the tracheobronchial mucosa. Therapy, including prednisolone, improved the skin lesions as well as the chest X-ray and bronchoscopic findings. Tracheobronchial and pulmonary lesions were followed before, during and after treatment of TEN.

Bronchi↗
PubMed1994

A new surgical technique (left upper abdominal evisceration) for advanced carcinoma of the gastric stump.

In spite of recent advances in the early diagnosis of gastric cancer by mass screening, gastric stump cancers following gastrectomy are still diagnosed at a highly advanced stage, and the surgical results remain very poor. Involvement of the fourth level lymph node stations, local peritoneal carcinomatosis and tumor growth invading the neighboring organs are frequently observed in advanced stump cancers. With the aim of achieving complete resection of these tumors, left upper abdominal evisceration (LUAE) + R4 gastrectomy was performed in 29 patients (Group B) with stump cancer as a radical surgical procedure. The survival of these patients was compared with that of 74 patients (Group A) who underwent total gastrectomy with or without pancreaticosplenectomy. Duration of surgery blood loss, and incidence of postoperative complications were similar with the two methods. When the survival rates were compared, the 5-year-survival rate in stage IV cases was higher for Group B than for Group A. LUAE + R4 gastrectomy is a rational technique for the surgical treatment of stage IV gastric stump cancer.

Adrenalectomy↗
PubMed1993

(R)-1,2,3,4-tetrahydro[1]benzothieno[2,3-c]pyridines: novel optically active compounds with strong 5-HT1A receptor binding ability exhibiting anticonflict activity and lessening of memory impairment.

(R)-1,2,3,4-Tetrahydro[1]benzothieno[2,3-c]pyridine derivatives (60-114) were synthesized. The (R)-isomers have affinity for the 5-HT1A receptor while the (S)-isomers have no such ability. The affinity of the (R)-isomers was discussed on the basis of structure-activity relationships between the affinity and hydrophobicity of the (R)-isomers. Compounds 71 and 107, which are representative derivative compounds, have anticonflict activity and lessening of memory impairment. In particular, compound 107 cannot bind to receptors other than the 5-HT1A receptor, demonstrating that it is a unique compound with a different mechanism of action from that of conventional anxiolytics.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1993

Mitogenic activation of the Ras guanine nucleotide exchange factor in NIH 3T3 cells involves protein tyrosine phosphorylation.

We report biochemical evidence that epidermal growth factor and platelet-derived growth factor stimulate the Ras guanine nucleotide exchange factor activity in quiescent NIH 3T3 cells. Moreover, the exchange activity is constitutively enhanced in NIH 3T3 cells transformed by Src and ErbB2 oncogenic tyrosine protein kinases (TPKs), whereas transformation by oncogenic Mos and Raf does not alter the activity. GTPase-activating protein activity was not affected under these conditions. Overexpression of pp60c-Src mutants containing activated and suppressor TPK mutations resulted in stimulation and inhibition of the exchange factor activity, respectively. A TPK inhibitor, genistein, prevented the activation of the exchange factor in epidermal growth factor/platelet-derived growth factor-treated cells and src-transformed cells. Furthermore, the exchange factor activity bound to an anti-phosphotyrosine antibody immunoaffinity column. These findings suggest that the guanine nucleotide exchange factor, but not GTPase-activating protein, plays a major role in the Ras activation in cell proliferation initiated by growth factor receptor TPKs and malignant transformation by oncogenic TPKs and that tyrosine phosphorylation of either the exchange factor or a tightly bound protein(s) may mediate the activation of the exchange factor by these TPKs.

3T3 Cells↗
PubMed1993

Transmembrane calcium influx associated with von Willebrand factor binding to GP Ib in the initiation of shear-induced platelet aggregation.

We found that the binding of multimeric vWF to GP Ib under a shear force of 108 dynes/cm2 resulted in the transmembrane flux of Ca2+ ions with a two- to three-fold increase in their intracellular concentration ([Ca2+]i). The blockage of this event, obtained by inhibiting the vWF-GP Ib interaction, suppressed aggregation. In contrast, the blockage of vWF binding to GP IIb-IIIa, as well as the prevention of activation caused by increased intracellular cAMP levels, inhibited aggregation but had no significant effect on [Ca2+]i increase. A monomeric recombinant fragment of vWF containing the GP Ib-binding domain of the molecule (residues 445-733) prevented all effects mediated by multimeric vWF but, by itself, failed to support the increase in [Ca2+]i and aggregation. These results suggest that the binding of multimeric vWF to GP Ib initiates platelets aggregation induced by high shear stress by mediating a transmembrane flux of Ca2+ ions, perhaps through a receptor-dependent calcium channel. The increase in [Ca2+]i may act as an intracellular message and cause the activation of GP IIb-IIIa; the latter receptor then binds vWF and mediates irreversible aggregation.

Biological Transport↗
PubMed1993

Kinetic changes and experimental carcinogenesis after Billroth I and II gastrectomy.

To determine the risk of gastric remnant cancer according to the type of surgical reconstruction, the distal two-thirds of the glandular stomach was resected in male Wistar rats, followed by gastroduodenostomy (Billroth I anastomosis) or gastrojejunostomy (Billroth II anastomosis). No carcinogens were given and the animals were killed 50 weeks after operation. No cancers developed in 22 rats undergoing Billroth I gastrectomy, but five of 24 with Billroth II anastomosis had adenocarcinoma (P < 0.05). All carcinomas were confined to the stoma. Animals with Billroth II anastomosis had a more advanced grade of mucosal atrophy at the stoma, with a higher incidence of cystic dilatation, submucosal adenocystic proliferation and pseudopyloric metaplasia (P < 0.05). Cell kinetics in the stomal mucosa after Billroth II gastrectomy showed an increased cell count in the proliferative zone, longer duration of S phase and increased cell cycle time (P < 0.05). These results suggest that Billroth II gastrectomy carries a greater risk of cancer than the Billroth I procedure.

Anastomosis, Surgical↗
PubMed1993

Facioscapulohumeral syndrome with sensorineural hearing loss and abnormality of retinal vessels.

A 23-year-old man was recognized as a sporadic case of facioscapulohumeral syndrome (FSH syndrome). He was a case of early onset, and there was severe atrophy of skeletal muscles, although muscle biopsy was normal. Electromyogram revealed neurogenic changes. This patient also had severe sensorineural hearing loss and a mild abnormality of retinal vessels. It is known that some FSH dystrophy or FSH spinal muscular atrophy patients have such coincidental complications. The cause of these coincidences is still unclear, but their occurrence suggests the pleiotropy of the FSH syndrome.

Adult↗
PubMed1993

[Evaluation of coronary flow and myocardial ischemia by transvenous and intracardiac two-dimensional echocardiography].

The purpose of this study was to observe ventricular wall motion in myocardial ischemia and to image coronary artery flow by transvenous intracardiac two-dimensional echocardiography. Ten mongrel dogs (body weight 24-34 kg) were anesthetized by intravenous sodium pentobarbital (25 mg/kg) and ventilated using a Harvard respirator after tracheotomy. Real-time Doppler two-dimensional echocardiography (ALOKA SSD-870) and a transesophageal probe (5 MHz, 24 elements, diameter 6.8 mm, phased array transducer) were used. The probe was introduced into the right atrium via the femoral vein. Myocardial ischemia was induced under fluoroscopic control by the inflation of a balloon catheter in the coronary artery, or by beads embolization of the coronary artery in closed-chest dogs, or by ligation of the coronary artery after a left or right thoracotomy. The wall motion of the right and left ventricles was observed by using the probe positioned in the lower right atrium. Visualization of the coronary artery and the flow velocity were studied with the probe in the mid right atrium. 1) Imaging: The left coronary artery, left main coronary artery and left anterior descending artery were easily observed by the probe positioned in the mid right atrium. The blood flow velocity in the left main coronary artery was consistently recorded. Changes in the blood flow velocity by coronary vasodilators such as dipyridamole, isosorbide dinitrate and nicorandil were clearly detected. 2) Detection of the myocardial ischemia: During the right coronary artery occlusion the right ventricle showed marked dilatation and hypokinesis, and the interventricular septum showed paradoxical movement and was displaced towards the left ventricular cavity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Correlation between DNA ploidy and clinical features in smooth muscle tumors of the gastrointestinal tract.

Paraffin-embedded tissue samples from 51 surgically resected, gastrointestinal smooth muscle tumors (10 leiomyomas, 5 leiomyoblastomas and 36 leiomyosarcomas) were assayed for nuclear DNA content, and the results were examined for correlation with clinico-pathological variables (tumor size, cellularity and mitosis) and prognosis. Twenty-four (47%) of the 51 tumors, consisting of 3 (30%) of the 10 leiomyomas, 2 (40%) of the 5 leiomyoblastomas and 19 (53%) of the 36 leiomyosarcomas, were identified as aneuploid. A close correlation was found between the mitotic index and the tumor size ( = 0.528; P < 0.001). The DNA ploidy pattern of the leiomyosarcoma was closely correlated with the patient survival periods (P = 0.06). The estimated median survival period was 73 months for patients with diploid tumors, and 51 months for those with aneuploid tumors. The 10-year survival rate for aneuploid tumors was lower than that for diploid tumors (P < 0.001). The measurement of DNA content may provide an index of prognostic value in gastrointestinal leiomyosarcomas.

Adult↗
PubMed1993

[Experimental studies on the development of residual stomach cancer--comparison of Billroth I and Billroth II].

The effects of duodenogastric reflex on the development of residual stomach cancer and cell proliferation kinetics were investigated in Wistar rats. Billroth II resection (B-II group) was performed on 24 rats and Billroth I resection (B-I group) was performed on 22 rats. The incidence of cancer in the B-II group was 20.8%, though no cancer was noted in the B-I group. The incidences of the pseudopyloric gland, dilated gland and gastritis cystica profunda in the B-II group were significantly higher than those in the B-I group. The degree of mucosal atrophy was greater in the B-II group than in the B-I group. The stomal area in the B-II group had expansion of proliferative zone as well as increased S-phase duration and turn over time, compared with those in the B-I group. The sequence of histological and proliferative events associated with duodenogastric reflux suggests that the residual stomach in the B-II group is susceptible to the development of cancer.

Animals↗
PubMed1992

Trace analysis of quinapril and its active metabolite, quinaprilat, in human plasma and urine by gas chromatography-negative-ion chemical ionization mass spectrometry.

A highly specific and sensitive method for the simultaneous determination of quinapril and its active metabolite, quinaprilat, in human plasma and urine by gas chromatography-negative-ion chemical ionization mass spectrometry is described. Quinapril and quinaprilat were extracted from human plasma and urine by using a Bond-Elut C18 cartridge. The plasma or urine extract was treated with pentafluorobenzyl bromide followed by trifluoroacetic anhydride to convert quinapril and quinaprilat into their pentafluorobenzyl-trifluoroacetyl derivatives, which were analysed by a selected-ion monitoring method using deuterium-labelled internal standards. The limits of quantitation for both quinapril and quinaprilat were 0.05 ng/ml in plasma and 0.5 ng/ml in urine. The proposed method is applicable to pharmacokinetic and clinical pharmacological studies with satisfactory reliability.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1992

Nerve growth factor stimulation of the Ras-guanine nucleotide exchange factor and GAP activities.

The biological activity of Ras proteins is thought to be controlled by the guanine nucleotide exchange factor and the guanosine triphosphatase activating protein (GAP). Treatment of rat pheochromocytoma PC-12 cells with nerve growth factor (NGF) increased the amount of active Ras guanosine triphosphate complex and stimulated the activities of both the guanine nucleotide exchange factor and GAP. In PC-12 cells that overexpressed the tyrosine kinase encoded by the trk proto-oncogene (a component of the high-affinity NGF receptor), the NGF-induced activation of the regulatory proteins was potentiated. These results suggest that the NGF receptor system enhances the activities of both the guanine nucleotide exchange factor and GAP and that the activation of Ras might be controlled by the balance in activity between these two regulatory proteins.

Animals↗
PubMed1992

Correlation of c-erbB-2 protein expression and lymph node status in early gastric cancer.

For the prediction of nodal status of early gastric cancer, sections of formalin-fixed, paraffin-embedded tissue from 220 early gastric cancers were analyzed immunohistochemically, using a polyclonal antibody against erbB-2 protein. The data of erbB-2 protein expression have been correlated with pathologic data, and a logistic regression analysis was made for the estimation of the significant factors responsible for lymph node metastasis. A pattern consistent with cell membrane staining was regarded as most specific for the erbB-2 expression. There were 22 (10%) cancers with evidence of erbB-2 protein expression. Positive staining was associated with only lymph node metastasis. The risk of lymph node metastasis was 3-fold greater in tumors having erbB-2 protein expression than in tumors without the expression. When the erbB-2 tissue status and clinicopathological parameters were entered into the logistic regression analysis, erbB-2 protein expression emerged as one of the independent significant factors for lymph node metastasis. These results indicate that early gastric cancer with erbB-2 protein expression may represent a potential risk of lymph node metastasis.

Biomarkers, Tumor↗
PubMed1992

Intravascular ultrasound imaging in human peripheral and coronary arteries in vivo.

To determine the feasibility of intravascular ultrasound imaging in vivo, a miniaturized high frequency transducer catheter was introduced into human peripheral (n = 10) and coronary (n = 4) arteries. Cross-sectional ultrasound images were obtained from iliofemoral arteries in 10 patients using a 20 MHz transducer catheter (1.2 mm in diameter) and from coronary arteries in 4 patients using a 30 MHz transducer catheter 5 French size (Fr) following successful coronary angioplasty. Ultrasound images obtained from peripheral arteries showed a three-layered appearance (echo-reflective intima, echo-lucent media and echo-reflective adventitia) in the normal arteries. In diseased arteries, the location, amount and extent of atheromatous plaque were clearly documented. The arterial diameters measured by ultrasound closely correlated with the measurements by angiography (r = 0.91) in the peripheral arteries. Coronary angiograms obtained following balloon angioplasty revealed smooth edges at the dilatation sites without significant narrowing in all patients. However, a significant amount of residual atheromatous plaque was clearly observed on the ultrasound images at the previously dilated sites. Coronary dissection, which was identified as an echo-lucent area behind the plaque, was noted in 2 patients. Ultrasound images also revealed the presence of calcium in the plaque which was unrecognized on the angiograms in 3 patients. In addition, direct measurement of the lumen cross-sectional area was possible on the ultrasound images.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteriosclerosis↗