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Biomedical subjects

T Shimura

Publications and source records attributed to T Shimura.

At least 55 records · Page 3Linked to original sources
PubMed1985

Ultrastructure of cerebellar hemangioblastoma. Some new observations on the stromal cells.

Five cases of hemangioblastoma were studied by electron microscopy with particular attention to the stromal cells and their surrounding structures. Most of the stromal cells of the tumor had abundant clear cytoplasm containing rough endoplasmic reticulum, mitochondria, scattered fibrils, and large lipid inclusions. They were usually aggregated without intervening cells. In the perivascular areas, their surfaces facing the perivascular collagen were surrounded by basal lamina. Their apposed cell membranes had occasional adhesive devices. Occasional, long, apparently cylindrical processes of the stromal cell cytoplasm were observed in some cases. These processes contained intermediate filaments of undetermined nature and microtubules. In the border zone between the tumor and the surrounding brain, the stromal cells were occasionally surrounded by narrow sheets of dark cell processes containing fibrils and glycogen granules, consistent with astrocytic processes. Altered neuronal elements were also observed in this area.

Adult↗
PubMed1985

Nonlinear parameter tomography system using counterpropagating probe and pump waves.

In this paper, a novel tomographic system for imaging the nonlinear parameter (B/A) of biological objects is described. This parameter is closely related to the detailed properties of tissue, and may well provide a new powerful tool for ultrasonic tissue characterization. In our new system, an impulsive, relatively high power (10 mW/cm2), low frequency pump wave is applied from the opposite direction of a cw low intensity probe wave of high frequency (5 MHz) so that the phase of the probe wave is modulated sequentially by the product of the nonlinear parameter (B/A) along the beam (x axis) and the pressure of the impulsive pump wave. This modulated probe wave is detected and demodulated to derive the distribution of (B/A) along the x axis. Many responses are averaged to increase the S/N ratio. Inverse or other filtering operations are applied to widen the frequency bandwidth of the pump wave. The entire system is realized in hardware. The counterbeam orientation makes the imaging system compact, with easy access to many parts of the human body. Its resolution is two times that of the perpendicular system proposed previously by us and the attenuation of the pump wave can also be compensated for easily. A practical system aimed at breast and liver diagnosis is described. The principle of the method and the system construction are described. B/A images of several objects are given.

Animals↗
PubMed1985

Evaluation of postoperative intratumoral injection of bleomycin for craniopharyngioma in children.

Total excision is the treatment of choice in preventing the relapse of craniopharyngioma, but for tumors involving an extensive area, it is often associated with increased risks of complications. The efficacy of postoperative radiotherapy has not yet been established. The authors have performed minimal tumor excision followed by intensive injection of bleomycin into the remaining tumor as postoperative adjuvant therapy in seven children with craniopharyngioma. Long-term outcome in the children with cystic-type tumors containing little or no solid tissue has proven the regimen to be more advantageous than total excision.

Adolescent↗
PubMed1985

[Anticancer treatment with a combination of antimetabolites of polyamine and pyrimidine].

A combined efficacy of the polyamine antimetabolites, alpha-difluoromethylornithine (DFMO) and methylglyoxal-bis-guanylhydrazone (MGBG) with two fluorinated pyrimidines was studied. DFMO, MGBG, 5-FU and 5'-deoxy-5-fluorouridine (5'-DFUR) were administered intraperitoneally to BALB/c nu/nu mice bearing xenotransplanted human gastric cancer for 5 consecutive days. Similar antitumor efficacies were observed in 3 groups treated with DFMO plus MGBG, DFMO, MGBG plus 5-FU as well as DFMO, MGBG plus 5'-DFUR. The two groups on 5-FU or 5'-DFUR alone did not differ in antitumor effects from the control, although reasonable levels of 5-FU were involved in tumor tissues. Hepatic and splenic 5-FU levels after 5-FU administration were significantly higher than those after 5'-DFUR, and marked decrease in mouse body weight was caused by 5-FU alone as well as 5-FU plus polyamine antimetabolites for 5 consecutive days. DNA biosynthesis and spermine levels in the tumor tissues on day 2 after cessation of the treatments dropped in 3 groups with DFMO plus MGBG, DFMO, MGBG plus 5'-DFUR as well as DFMO, MGBG plus 5-FU, while on day 6 there was little difference between the control and treated groups. These data suggest that combination with 5-FU or 5'-DFUR does not enhance the antitumor activity of polyamine antimetabolites by this experimental regimen.

Animals↗
PubMed1985

[Brain tumor induced in dogs by intracerebral inoculation of SR-RSV induced cultured tumor cells--electron microscopic study].

An experimental transplantable canine brain tumor model with the advantages of rapid tumor growth within 10 days and relative safety for the investigator is presently available. The tumor is produced by intracerebral inoculation of cultured cells derived from a canine brain tumor induced by the Schmidt-Ruppin strain of the Rous-Sarcoma virus (SR-RSV). It has potential use as a model in experiments designed to evaluate the effectiveness of chemotherapy and radiotherapy with serial computerized tomography scans. However, characterization of the induced tumor is essential. Ideally, it should have features attributable to glioma and/or neuroectodermal tumors. Utilizing the technique of intracerebral inoculation of cells cultured from the original dog brain tumor induced by SR-RSV, Salcman et al identified the tumor they induced in brains of mongrel puppies as a glioma by light microscopic criteria (Reference). The purpose of our study was to further characterize this experimental tumor by electron microscopic and immunohistochemical techniques. Tumor was induced in 6 mongrel puppies. Stains of the tumor for immunohistochemical reactivity to glial fibrillary acid protein, S-100 protein and 210K neurofilament protein were all negative. With the electron microscope, the intracerebral tumor cells were mostly undifferentiated. They had a few cell processes, occasional punctate adhesions and some microvilli-like structure. The tumor cell nucleus was usually oval shaped and sometimes had nuclear indentations. The cytoplasm contained abundant free ribosomes, some rough endoplasmic reticulum and mitochondria. Collagen fibers and basal lamina were not observed in the intercellular spaces. The capillaries within the tumor were characterized by proliferation of immature endothelial cells which were non-fenestrated.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

[Cyclic AMP- and ATP-mediated stimulation of DNA synthesis following partial hepatectomy by prostaglandin-E1 in D-galactosamine injured liver].

D-galactosamine (D-gal) damaged rats were infused with Prostaglandin E1 (PGE1) through a peripheral vein for 40 min. before and after partial hepatectomy. DNA synthesis following 68% partial hepatectomy was severely inhibited by the pretreatment of D-galactosamine. PGE1 infusion (0.5, 1.0 microgram/kg/min) enhanced the DNA synthesis inhibited by D-gal 600 mg/kg significantly (p less than 0.01). After 20 min. of PGE1 infusion cyclic AMP levels of liver tissue was increased as compared with saline infusion in D-gal (600 mg/kg)-damaged rat (p less than 0.05). Also 20 min. and 3 hour after partial hepatectomy. ATP levels of liver tissue was enhanced in PGE1 treated group (p less than 0.05). However the doses of PGE1 infused in this investigation could not increase the hepatic tissue blood flow measured by hydrogen gas clearance method. These results suggest that PGE1 enhance DNA synthesis of injured liver after partial hepatectomy by the mechanism which PGE1 stimulate cyclic AMP production and increase ATP level in hepatic tissue.

Adenosine Triphosphate↗
PubMed1985

[Preoperative cancer chemotherapy for gastric cancer].

Preoperative cancer chemotherapy for gastric cancer was reviewed with special emphasis on histologic findings and survival. Preoperative chemotherapy with intravenous, split administration of MMC 40 mg caused considerable damage to "micro-solitary metastatic foci" in metastatic lymph nodes. In view of the lipid-adsorbing ability of the lymphatic stream, emulsified 5-FU was used orally in 182 patients with gastric cancer; histologic findings revealed that the emulsified 5-FU enhanced the antitumor efficacy for metastatic lymph nodes as well as the primary lesion. However, the 5-year survival rate for gastric cancer patients undergoing preoperative emulsified 5-FU therapy did not differ from the control, with only the exception of patients with Stage III gastric cancer. On the other hand, combined therapy involving preoperative intra-arterial infusion and surgery was carried out in 62 patients with gastric cancer. These preoperative treatments using MMC, 5-FU, VLB, MTX and/or cytosine arabinoside entailed continuous infusion for 15 to 20 hours; the histologic changes observed revealed marked antitumor effects on the primary focus as well as metastatic lymph nodes. The five-year survival rate for the 62 patients was compared with that for 99 patients with gastric cancer in the corresponding period. The survival rate was analyzed based on the degree of serosal invasion. The overall survivals in the 62 patients were higher than those in the controls for the first 3 years. At 4 to 5 years, the survival rates for both the treated and control groups were approximately equal. In patients without serosal invasion, the survival rates were higher in treated cases than in the controls for the first 2 years. Thirty-nine patients with serosal invasion had significantly higher survival rates than the controls for the first 3 years. The survival rates for the treated patients with cancerous infiltration of ther organs were about the same as those for the corresponding control patients.

Administration, Oral↗
PubMed1985

[Pathology of intracerebral hemorrhage in ruptured aneurysms of the posterior communicating artery at its origin from the internal carotid artery].

There were thirty-two autopsied cases of ruptured aneurysms at the junction of the internal carotid and posterior communicating arteries in the file of Montefiore Medical Center from 1948 to 1983 (Table 1). The age range of the patients was 11-83 years. Seven were men and twenty-five were women. Fifteen had previous surgery; either clipping of the neck of the aneurysm or ligation of the common carotid artery. Analysis of the hemorrhage associated with the ruptured aneurysms revealed two distinct patterns. One is subarachnoid hemorrhage alone (18 cases) and another is subarachnoid hemorrhage and intraventricular rupture through the temporal horn (14 cases). These aneurysms did not produce a large intracerebral hematoma in the temporal lobe because they ruptured into the temporal horn. Among the post-operative cases (14 cases), only 3 cases had intraventricular hemorrhage. Correlation of these autopsy findings with CT Scans revealed that an intraventricular hematoma in the temporal horn could be interpreted as a large intracerebral hematoma in the temporal lobe.

Adolescent↗