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Biomedical subjects

T Tashiro

Publications and source records attributed to T Tashiro.

At least 289 records · Page 16Linked to original sources
PubMed1989

[Silicosis and lung cancer].

A clinicopathological analysis was carried out on 50 cases of lung cancer with silicosis diagnosed from April 1975 to March 1988. All patients were males and the age distribution ranged from 47 to 85 years with a mean of 63.5 at diagnosis. They had been exposed to silica in tunneling for 3 to 42 years, with an average of 15.1. Forty eight cases smoked. Histologically, squamous cell carcinoma was the most common with 29 cases, followed by 10 small cell carcinomas, 6 adenocarcinomas, 4 large cell carcinomas and one adenosquamous carcinoma. Thirty seven tumors were located in peripheral regions, mostly upper lobe or S6, while 13 tumors were in large bronchi. As the most common histological types of lung cancer with silicosis were squamous cell carcinoma and small cell carcinoma, some carcinogens might be involved in tumorigenesis. Silica alone is not considered to be a carcinogen, however, silica containing adsorbed polycyclic aromatic hydrocarbons from cigarette smoking or from industrial pyrolysis can act as a carcinogen or promoter.

Adenocarcinoma↗
PubMed1989

[Clinical prospective study of surgical treatment of pterygium].

Pterygium is a kind of degenerative lesion of the ocular conjunctiva and is thought to be hyperaemia of fibrovascular tissue onto the cornea caused by various factors. The most frequently used treatment for pterygium at present is surgery. Various surgical procedures and postoperative treatments for pterygium have been reported, however, the postoperative recurrence rates are somewhat high. Therefore, until now we have had no satisfactory clinical management of pterygium. The results of our method for surgical treatment of pterygium are given and compared with those described in many other reports. From this comparison, our clinical surgical treatment of pterygium, which is the so-called "bare sclera" technique, is evaluated to give the best management without serious complications and recurrences.

Eye Diseases↗
PubMed1989

[A case of pituitary adenoma presenting binasal inferior quadrants hemianopsia].

Visual field defect due to pituitary adenoma ordinarily shows bitemporal hemianopsia. But we experienced a case presenting binasal inferior quadrants hemianopsia. A 60-year-old woman was admitted to our hospital complaining of headache and blurred vision. At ophthalmologic examination, the visual acuity on the right was 0.02 and on the left 0.3. Visual field showed a loss of bilateral inferior nasal quadrants. There was neither pallor nor edema of either of the optic disks. A computerized tomography (CT) scan showed an enhancing mass in the intra- and suprasellar region. But despite remarkable suprasellar expansion of the tumor, the straight view of bilateral carotid angiograms revealed no elevation of the first part of the anterior cerebral arteries (ACA). On the lateral view, the terminal portion of the precommunicating part of the left ACA showed rather marked anteroinferior displacement. 2 mm thin sliced CT scans at the suprasellar region revealed that the left internal carotid artery had been touching the lateral portion of the tumor and the ACA had been displaced anteriorly by the tumor. Two weeks after admission, transsphenoidal tumor resection was carried out. Total removal was achieved and histological examination showed that the tumor was nonfunctioning chromophobe adenoma. The postoperative course was uneventful except for transient diabetes insipidus. The patient's visual acuity rapidly improved to 0.8 on the right and 0.5 on the left two weeks after operation. Although there was still a tendency for left inferior nasal field defect, remarkable improvement was obtained subjectively and objectively. According to the findings of CT scans and cerebral angiograms, binasal hemianopsia may have been produced by the mechanism as follows.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenoma, Chromophobe↗
PubMed1989

Balloon electric shock ablation. Effects on ventricular structure, function, and electrophysiology.

We have recently developed a transatrial balloon approach for intraoperative endocardial mapping of ventricular tachycardia, which can be performed in the intact ventricle. In selected patients, we have eliminated the arrhythmia by passing a series of electric currents through specific beads on the balloon array. The goal of this new technique, balloon electric shock ablation, is to create a homogenous scar in the subendocardial target area identified by mapping. Experimental data exist on the effects of catheter delivery of electric discharges to the myocardium, but no data are available on the effects of balloon electric shock ablation. We have performed balloon electric shock ablation in animals (nine cathodal shocks of 100 J given through a 4 cm2 electrode grid). Ventricular function was assessed at 6 weeks and compared with function after a simple ventriculotomy and with function in control animals having no operation. Gated nuclear ventriculograms were obtained during volume loading. Myocardial performance and diastolic pressure volume relationships were determined for the three groups. After balloon electric shock ablation or ventriculotomy, left atrial pressures were increased at similar end-diastolic volumes, which indicated decreased ventricular compliance. The trend reached statistical significance (compared with data from control animals) only in the group undergoing balloon electric shock ablation. Myocardial performance (stroke work index/end-diastolic volume relationship) was unchanged in the three groups. In the long-term balloon electric shock ablation preparation, an electrophysiologic study (including burst pacing) failed to induce ventricular arrhythmias. At 6 weeks, the lesion created by balloon electric shock ablation was a layer of homogenous mature scar with sharply defined borders. There was no evidence of additional injury to the surrounding myocardium or to the mitral valve apparatus. These studies show that delivery of a series of electric shocks through a 1 cm balloon grid of electrodes can create an area of homogeneous, electrically inert scar and that this procedure when performed in healthy dog hearts has no significant effect on the structure and function of the rest of the left ventricle.

Animals↗
PubMed1989

Stable and dynamic forms of cytoskeletal proteins in slow axonal transport.

Dynamic organization of the axonal cytoskeleton was investigated by analyzing slow axonal transport of tubulin and other major cytoskeletal proteins in the motor axons of rat sciatic nerve 1-4 weeks after injection of L-35S-methionine into the anterior horn area of L3-L5 lumbar spinal cord. A large proportion (50-65%) of tubulin transported in the axon was found to be insoluble when extracted with 1% Triton at 4 degrees C. This cold-insoluble tubulin was also resistant to other microtubule-destabilizing agents such as Ca2+, colchicine, and nocodazole, suggesting that it corresponded to the stably polymerized tubulin specific to the axon. From the cold-soluble fraction, microtubules containing a distinct set of associated proteins were recovered by the taxol-dependent procedure. Transport pattern of cold-soluble and -insoluble tubulin in this system showed a time-dependent broadening of the tubulin wave resulting in the appearance of a new faster wave enriched in cold-soluble tubulin. The slower and the faster waves of tubulin were defined as group V or slow component a (SCa) and group IV or slow component b (SCb), respectively, with respect to the 2 subcomponents of slow transport originally described in the optic system. However, compositions of groups IV and V in sciatic motor axons differed significantly from those of the optic system. Actin also exhibited a clear dual wave pattern of transport that coincided well with that of tubulin, indicating that both actin and tubulin were the major components of both groups IV and V.(ABSTRACT TRUNCATED AT 250 WORDS)

Actins↗
PubMed1988

Direct projections from the subthalamic nucleus of Luys to the spinal cord in the Japanese monkey.

Injection of large amounts of a mixture of horseradish peroxidase and wheat germ agglutinin-horseradish peroxidase conjugate into the upper cervical segments of the spinal cord in the Japanese monkey (Macaca fuscata) led to the retrograde labeling of a small number of neuronal cell bodies within the rostral part of the subthalamic nucleus of Luys. Direct projection from the subthalamic nucleus to the spinal cord appeared to be much less prominent in the Japanese monkey than in the cat and rat.

Afferent Pathways↗
PubMed1988

Distribution of axons exhibiting both enkephalin- and serotonin-like immunoreactivities in the lumbar cord segments: an immunohistochemical study in the cat.

Axons exhibiting both enkephalin- and serotonin-like immunoreactivities were observed by the double immunofluorescence method in the lumbar cord segments of the cat. Double-labeled axons were seen most frequently in laminae I, IIa and the lateral part of lamina V. They were also distributed in other parts of the dorsal horn and lamina X (especially in the dorsal part), but rarely found in laminae VII, VIII and IX. After cervical hemicordotomy the vast majority of double-labeled axons disappeared from the spinal gray ipsilateral to the lesion.

Animals↗
PubMed1988

Effects of taxol on slow and fast axonal transport.

Axonal transport of tubulin in the rat sciatic nerve is almost completely inhibited by a single subepineural injection of taxol, without affecting that of neurofilament proteins. Actin and a large number of polypeptides cotransported with actin as minor components are also blocked by taxol, although to a lesser extent. Fast axonal transport is essentially free from the inhibitory effect of this drug. Although previous models have suggested that slow axonal transport involves the bulk movement of cytoskeletal structures, these results suggest that such transport may involve an equilibrium between polymerised and depolymerised forms of the axonal cytoskeleton.

Actins↗
PubMed1988

The distribution of infrahyoid motoneurons in the cat: a retrograde horseradish peroxidase study.

The distribution of cell bodies and the peripheral course of axons of infrahyoid motoneurons were examined in the cat by the retrograde horseradish peroxidase method after application of the enzyme to the peripheral nerve branches supplying the infrahyoid muscles. Infrahyoid motoneurons were observed to constitute a slender cell column, which extended from a level of the caudal part of the hypoglossal nucleus usually to the most caudal level of the C1 cord segment, or occasionally to the lower levels of the C2 cord segment. The cell column was located immediately lateral to that of motoneurons of the spinal accessory nerve. In the cell column, thyrohyoid motoneurons were distributed in the medulla oblongata; sternohyoid motoneurons were located somewhat more cranially than sternothyroid motoneurons in the medulla oblongata and cervical cord. However, the level of craniocaudal distribution of thyrohyoid, sternohyoid or sternothyroid motoneurons highly overlapped. The experiments involving severance of the hypoglossal and/or cervical nerves indicated that axons of thyrohyoid and sternohyoid motoneurons passed via the roots of both hypoglossal and C1 nerves, that axons of sternohyoid motoneurons passed via the C1 nerve roots, and that axons of infrahyoid motoneurons innervating the conjugated part of the sternohyoid and sternothyroid muscles passed usually via the C1 nerve roots, or occasionally via the roots of both C1 and C2 nerves.

Animals↗
PubMed1988

Amygdaloid pathway to the trigeminal motor nucleus via the pontine reticular formation in the rat.

The connections of the amygdala with the trigeminal motor nucleus were studied by light and electron microscopy. Horseradish peroxidase (HRP) experiments showed that the pontine reticular formation, ventromedial to the spinal trigeminal nucleus at the level rostral to the genu of the facial nerve, receives fibers from the central nucleus of the amygdala ipsilaterally and sends fibers to the trigeminal motor nucleus contralaterally. Electron microscopic observations were carried out on the pontine reticular formation after electrolytic lesions in the central nucleus of the amygdala and HRP injections into the contralateral trigeminal motor nucleus were made on the same animal. These experiments using the combined degeneration and HRP technique clearly demonstrated that degenerating amygdaloid fibers made synaptic contacts with retrogradely labeled neurons.

Amygdala↗
PubMed1988

Specificity of action on neuropeptides of an endopeptidase from the synaptosomal membranes of guinea pig brain.

An endopeptidase was solubilized and highly purified from the synaptosomal membrane fraction of guinea pig brain, and its specificity of action on various neuropeptides was investigated. It hydrolyzed specifically the Pro10-Tyr11 bond of neurotensin and showed a marked specificity toward Pro-X bonds present in the interior parts of various neuropeptides and related peptides. No cleavage, however, was observed at the first and second peptide bonds from the NH2-termini or from the COOH-termini of the peptides examined, suggesting that the enzyme requires both NH2- and COOH-terminal extentions of at least 3 residues from the scissile bond for its action. In addition, a limited number of other peptide bonds were cleaved, indicating that the enzyme is not strictly specific to Pro-X bonds. These results suggest the possible implication of this enzyme in the specific degradation of neurotensin and other peptide neurotransmitters in the synaptic cleft.

Amino Acid Sequence↗
PubMed1988

Pharmacokinetic approach to rational therapeutic doses for human tumor-bearing nude mice.

To improve clinical predictability from therapeutic results of various antitumor agents in human tumor/nude mouse models it seems to be important to use a dose pharmacokinetically equivalent to the clinical dose. Thus, we attempted to find the dose of a given drug that can reproduce in the nude mouse a plasma level similar to that seen in human patients treated with an effective dose of the drug based on comparative pharmacokinetic studies between man and nude mouse. As a result, those of 3 alkylating agents, mitomycin C, 3-[(4-amino-2-methyl-5-pyrimidinyl)methyl]-1-(2-chloroethyl)-1-nitrosourea (ACNU) and cyclophosphamide, and those of 2 antimitotic agents, vincristine and vinblastine, were estimated to be one-fourth or one-fifth of their maximum tolerated doses (MTD's). On the other hand, in the case of adriamycin, its MTD was approximately equivalent to its clinical dose pharmacokinetically. In contrast, clinically equivalent doses of 2 antimetabolites tested, 5-fluorouracil and methotrexate, were significantly greater than their MTD's; i.e., their plasma levels did not reach the effective clinical ones even when their MTD's were administered to the nude mice. These results suggest that the antitumor effects of most antitumor agents are over- or underestimated in this model when MTD's are used as a therapeutic dose, and indicate that the use of clinically equivalent doses determined pharmacokinetically is desirable.

Animals↗
PubMed1988

Responsiveness of human gastric tumors implanted in nude mice to clinically equivalent doses of various antitumor agents.

To reproduce clinical effects of various antitumor agents in the human tumor/nude mouse model, we investigated the responsiveness of 11 lines of human gastric tumor xenografts to doses of the agents pharmacokinetically equivalent to the respective clinical doses, which we designated the "rational dose" (RD). We found that the response rates to mitomycin C, 3-[(4-amino-2-methyl-5-pyrimidinyl]methyl-1-[2-chloroethyl]-1- nitrosourea (ACNU), adriamycin, 5-fluorouracil were 18%, and that to vinblastine was 30%; on the other hand, those to vincristine, methotrexate, and cyclophosphamide were poor. In contrast, in our previous study using the maximum tolerated doses, response rates to mitomycin C, ACNU, and vinblastine were as high as 64-82%, and those to adriamycin and 5-fluorouracil were 18%. When these results were compared with the clinical response rates of gastric tumors, as a whole, the results with RD's exhibited much better coincidence with the clinical data in terms of relative therapeutic potency, indicating the validity of the use of clinically equivalent doses instead of maximum tolerated doses in the human tumor model.

Animals↗