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Biomedical subjects

H Nakata

Publications and source records attributed to H Nakata.

At least 289 records · Page 16Linked to original sources
PubMed1987

[Agenesis of the left internal carotid artery with an ophthalmic artery arising from the posterior communicating artery].

A case of agenesis of left internal carotid artery is reported. The patient is a forty one-year-old house-wife with sudden episode of headache when she had a fever. CT scan of the head showed a small high density area in the right frontotemporal subcortical region. Four vessel cerebral angiography demonstrated negative lesion except for complete absence of the left internal carotid artery. The blood supply to the left cerebral hemisphere was provided both through the tortuous anterior communicating artery and through the enlarged left posterior communicating artery. Left ophthalmic artery arose from the left posterior communicating artery. The embryological developmental process of this kind of vascular anomaly as well as the relationship between intravascular hemodynamic stress and the induction of cerebral aneurysm were discussed in detail.

Adult↗
PubMed1986

[CT diagnosis of malignant thymoma].

Computed tomography (CT) findings of six cases of malignant thymoma were analyzed with eight cases of benign thymoma as a control and the usefulness of CT in their differential diagnosis was evaluated. 1) Three of the malignant thymomas showed a flat shape, while none of the benign ones showed such a configuration. All of the latter were round or oval. 2) The margin of the tumor was irregular and lobulated with evidence of invasion in 4 of the malignant thymomas. All of the benign tumors showed a smooth margin. 3) Intrathoracic metastasis was noted in 2 of the malignant thymomas. 4) CT numbers of the tumors overlapped in both benign and malignant thymomas. 5) Thus the CT observation of the shape, margin, and invasiveness of a tumor as well as evidence of intrathoracic metastasis makes the differential diagnosis between benign and malignant thymomas possible in most cases.

Adult↗
PubMed1986

Chemical modification of alpha 2-adrenoceptors. Possible role for tyrosine in the ligand binding site.

Tetranitromethane (TNM) is a reagent which reacts with the tyrosine and cysteine residues of proteins. Chemical modification of partially purified human platelet alpha 2-adrenoceptors with TNM resulted in an irreversible loss of binding activity. Typically, an 80-90% decrease in binding activity occurred with a 60-min exposure to 320 microM TNM. The loss of alpha 2-adrenoceptor activity caused by TNM could be prevented if alpha 2-adrenergic ligands were present during exposure of the receptor to TNM. The protection afforded by alpha 2-adrenergic ligands was dose-dependent and showed a positive correlation with the affinity of the ligand for the alpha 2-adrenoceptor. Prazosin, an alpha 1-specific antagonist, and propranolol, a beta-adrenergic antagonist, did not protect alpha 2-adrenoceptors against the inactivation caused by TNM. Saturation curve analysis revealed that the decrease in alpha 2-adrenoceptor activity caused by TNM was due to a decrease in Bmax with no change in Kd. alpha 2-Adrenoceptors were also inactivated with the sulfhydryl-specific reagent phenylmercuric chloride (PMC). The receptor inactivation caused by PMC could be reversed completely by subsequent treatment with dithiothreitol. Treatment of alpha 2-adrenoceptors with combinations of TNM and PMC showed that the receptor inactivation caused by TNM was most likely due to an interaction with tyrosine residues. These results indicate that tyrosine residues have a function in the conformational stability of alpha 2-adrenoceptors and may be directly involved with ligand binding to the receptor.

Binding Sites↗
PubMed1986

[Radiation therapy combined with hyperthermia in advanced cancer].

Radiation therapy combined with radiofrequency (RF) hyperthermia was performed on 5 advanced cancer patients. Included were one each with urinary bladder cancer, hepatoma with left axillary node metastasis, breast cancer, tongue cancer with left cervical metastasis, and mandibular cancer. All had large tumours, which were judged to be uncontrollable by radiotherapy alone. They were treated with irradiation (Linac: 10 MV X-ray 1.8-2.0 Gy/day, 5 days/week), followed within an hour by RF hyperthermia once or twice a week. Partial response was obtained in the urinary bladder cancer patient. Surface overheating around the margin of electrodes occurred in all but no severe complications were observed.

Breast Neoplasms↗
PubMed1986

[Examination of the fine interstitial changes of pneumoconiosis with high resolution computed tomography (HR-CT)].

High resolution CT was performed in 14 patients with fine interstitial changes of pneumoconiosis and Review image was evaluated for the diagnostic accuracy as compared with conventional chest roentgenogram. Of the 14 Patients in the study, 7 were divided category 1 by the ILO U/C classification, 4 were category 2, 3 were category 3. Studies of lung function showed obstructive ventilatory disturbance characterized by moderate reduction in FEV1.0% (58.6 +/- 16.5%) and V25/H (0.34 +/- 0.24 l/sec/m). HR-CT defined more sensitive in the presence of fine lung nodules than conventional X-p, and showed high contrast interfaces provided by the aerated lung. HR-CT was also of value in detecting bulla, bleb, peripleural changes and hilar lymphadenopathy. Radiologic-pathologic correlation was examined on the specimens of transbronchial lung biopsy in 4 patients, and revealed the diagnostic usefullness of HR-CT.

Adult↗
PubMed1986

Purification and characterization of the human platelet alpha 2-adrenergic receptor.

Human platelet alpha 2-adrenergic receptors have been purified approximately 80,000-fold to apparent homogeneity by a five-step chromatographic procedure. The overall yield starting from the membranes is approximately 2%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of radioiodinated protein from purified receptor preparations shows a single major band of Mr 64,000. The specific binding activity of the alpha 2-adrenergic receptor after four chromatographic steps is 14.5 nmol/mg protein. This value is consistent with the expected theoretical specific activity (15.6 nmol/mg) for a protein with a molecular mass of 64,000 daltons if it is assumed that there is one ligand-binding site/receptor molecule. The purified protein can be covalently labeled with the alkylating alpha-adrenergic ligand, [3H]phenoxybenzamine. This labeling is specific, and it shows that the Mr 64,000 protein contains the ligand binding site of the alpha 2-adrenergic receptor. In addition, the competitive binding of ligands to the purified receptor protein shows the proper alpha 2-adrenergic specificity. The alpha 2-adrenergic receptor contains an essential sulfhydryl residue. Thus, exposure of the purified receptor to the sulfhydryl-specific reagent, phenylmercuric chloride, resulted in an 80% loss of binding activity. This loss of binding activity was prevented when exposure to phenylmercuric chloride was done in the presence of alpha 2-adrenergic ligands, and it was reversed by subsequent exposure to dithiothreitol. Partial proteolysis of purified alpha 2-adrenergic receptors was obtained with Staphylococcus aureus V-8 protease, alpha-chymotrypsin, and papain. In a comparison with purified beta 2-adrenergic receptors, no common partial proteolytic products were found.

Blood Platelets↗
PubMed1986

Functional reconstitution of the alpha 2-adrenergic receptor with guanine nucleotide regulatory proteins in phospholipid vesicles.

We describe the successful reconstitution of functional interactions between an inhibitory adenylate cyclase-coupled receptor and various nucleotide-binding regulatory proteins in phospholipid vesicles. The receptor is the alpha 2-adrenergic receptor (alpha 2AR) which has been partially purified (approximately 500-5000-fold) from human platelet membranes. The nucleotide-binding regulatory proteins include purified preparations of human erythrocyte Ni and Ns, bovine retinal transducin and the recently discovered bovine brain No. Addition of the physiologic ligand, epinephrine, to vesicles containing the alpha 2AR and Ni results in stimulation of the GTPase activity in Ni. This stimulation of GTPase activity by epinephrine is prevented in the presence of the alpha-adrenergic antagonist, phentolamine, which indicates that a functional reconstitution of the alpha 2AR and Ni has been established. The maximum turnover number for the alpha 2AR-mediated epinephrine-stimulated GTPase activity in Ni is similar to the maximal turnover numbers obtained for the beta-adrenergic receptor-mediated isoproterenol-stimulated GTPase activity in Ns and the rhodopsin-mediated light-stimulated GTPase activity in transducin (0.5-1.5 mol of Pi released per min per mol of nucleotide regulatory protein). Functional similarities between the alpha 2AR and rhodopsin are observed in their interactions with the various nucleotide-binding regulatory proteins. Thus, both of these receptor proteins are capable of promoting the maximal activation of Ni and No while being much less effective in promoting the activation of Ns. However, there are differences between the alpha 2AR and rhodopsin in their interactions with transducin. Specifically, while rhodopsin will maximally activate transducin, the alpha 2AR is much less effective in promoting this activation (i.e. approximately 20% as effective as rhodopsin). Overall, these results suggest the following specificities of interaction: for rhodopsin, transducin approximately equal to Ni approximately equal to No much greater than Ns; while for alpha 2AR, Ni approximately equal to No greater than transducin greater than or equal to Ns.

Adenylyl Cyclases↗
PubMed1986

99mTc-methylene diphosphonate uptake by ossifications and calcifications of non-osseous metastatic tumors.

Two cases of extra-osseous uptake of 99mTc-methylene diphosphonate (MDP) by non-osseous metastatic tumors are reported. One was a metastasis with ossification in the abdominal wall from carcinoma of the sigmoid colon and the other was a metastasis with calcification from an ovarian carcinoma. The mechanism of extra-osseous uptake of 99mTc-MDP is discussed. Bone scintigraphy can be a potential means to assess tumor spread with ossifications and calcifications.

Abdominal Neoplasms↗
PubMed1986

Computed tomography for preoperative evaluations of lung cancer.

Computed tomography was evaluated for its accuracy in diagnosing mediastinal node metastases, direct chest wall invasion, and direct mediastinal invasion by lung cancer among 61 patients who subsequently underwent surgery. Using 15-mm diameter or larger mediastinal lymph nodes as the criterion for metastasis, the sensitivity was 36% (8/22); the specificity was 92% (34/37). The accuracy for direct chest wall invasion was relatively high, with a sensitivity of 100% (7/7) and a specificity of 92% (22/24). Direct mediastinal invasion had a sensitivity of 67% (4/6) and a specificity of 91% (10/11). These results suggest that the ability of computed tomography to diagnose mediastinal lymph node metastasis when such nodal size is used as a criterion is limited.

Humans↗
PubMed1986

Renal cell carcinoma originating from dysplastic kidney.

A case of renal cell carcinoma developing from a unilateral dysplastic kidney is presented. The patient was a 33-year-old woman who had lumbago one year and a half prior to death. Multiple abnormal uptakes of 67Ga were seen by scintigraphy. Bone marrow biopsy indicated adenocarcinoma but the primary site was unknown despite extensive examination. At autopsy the carcinoma was wide-spread but no obvious primary-appearing lesion was detected in all the organs except the left kidney. Incidentally the patient had unilateral (left) renal dysplasia. An elaborate study revealed the primary site of the carcinoma within the cystic structure of the dysplastic kidney. This tumor showed reactivity with Dolichos biflorus agglutinin associated antigen (DBA-Ag), soybean agglutinin (SBA), and peanut agglutinin (PNA) which have reactivity with renal tubules.

Adult↗
PubMed1986

Successful combination chemotherapy (cisplatinum, vinblastine, and bleomycin) against peritoneal dissemination of intracranial germ cell tumor.

We found combination chemotherapy with cisplatinum, vinblastine, and bleomycin (PVB therapy) effective in the treatment of a patient with a pineal germ cell tumor with peritoneal dissemination. The metastatic complication may have been attributable to the ventriculoperitoneal shunt tube. After the first course of PVB therapy, the disseminated tumors were decreased in size; no residual tumors were detected after the third course by laparoscopic examination, computed tomographic scanning, or echogram. Our results suggest that combined PVB therapy is effective in the treatment of extraneural metastasis from intracranial germ cell tumors.

Adult↗
PubMed1986

Time lag between pulmonary congestion and pulmonary edema in dogs.

The time course of pulmonary congestion and pulmonary edema was examined using a gravimetric method in 19 open-chest anesthetized dogs. Balloon catheters in the left atrium (LA) were inflated to elevate LA pressure more than 25 mmHg. The dogs were divided into 4 groups (G) according to the duration of the elevated LA pressure: G.1 (n = 6) as control; G.2 (n = 4) for 15 minutes; G.3 (n = 4) for 30 minutes; and G.4 (n = 5) for 60 minutes. Although no significant increase of extravascular lung water content (an indicator of pulmonary edema) was observed in G.2 (4.97 +/- 0.85 g/kg) and G.3 (4.46 +/- 0.96) compared with G.1 (4.02 +/- 0.88), a significant increase was observed in G.4 (6.81 +/- 1.21, p less than 0.05). Residual pulmonary blood content (an indicator of pulmonary congestion) was significantly increased in G.2, 3 and 4 compared with G.1. By light and electron microscopes, pulmonary congestion was revealed in G.2, whereas interstitial pulmonary edema was demonstrated only in G.4. Thus, it was concluded that pulmonary congestion occurred within 15 minutes, but pulmonary edema occurred 30 to 60 minutes after left atrial pressure was elevated more than 25 mmHg. This time lag may be an important factor in explaining the discrepancy between the elevated left atrial pressure and the clinical manifestation of pulmonary edema.

Animals↗