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Biomedical subjects

T Nakashima

Publications and source records attributed to T Nakashima.

At least 253 records · Page 14Linked to original sources
PubMed1996

Evidence of a direct action of taurine and calcium on biological membranes. A combined study of 31P-nuclear magnetic resonance and electron spin resonance.

To determine the actions of taurine and calcium on biological membranes, the effects of these compounds on the mobility of phospholipids of resealed and sonicated ghosts of human erythrocytes were investigated, using 31P-NMR spectroscopy. In addition, the effects of taurine and calcium on lipid fluidity were investigated by ESR spectroscopy, using a spin-labeling method with 5-doxyl stearic acid. The mobility of the membranes decreased following treatment with 10 mM taurine, but coadministration of 2.5 mM calcium blocked this effect. The fluidity of the membranes was not changed following treatment with 10 mM taurine, but decreased following coadministration of 2.5 mM calcium. These actions of taurine and calcium on the dynamics of biological membranes might explain, in part, the observation that most of the pharmacological effects of taurine on mammalian organs occur in the presence of calcium ions.

Calcium↗
PubMed1996

Procaine microinjection into the lower midbrain increases brown fat and body temperatures in anesthetized rats.

A tonic inhibitory mechanism on heat production was studied by microinjecting procaine into various regions of the brain while recording temperature changes of the interscapular brown adipose tissue (IBAT) and rectum in urethane-anesthetized rats at room temperature of 23-25 degrees C. Procaine microinjected bilaterally (10%, 1.0 mu l/site, 1.5 mm to midline) into the midbrain and the upper- to mid-pontine area of the reticular formation increased temperatures of the IBAT and rectum. The highest temperature rise (1.02 +/- 0.11 degrees C for IBAT, 0.64 +/- 0.06 degrees C for rectum) with the shortest onset latency (1.5 +/- 0.3 min for IBAT, 4.6 +/- 1.1 min for rectum) was observed when procaine was injected into the lower midbrain (the area between 6 and 7 mm posterior to the bregma, and 6.5 to 8.5 mm deep from the cortical surface). These regions include the retrorubral field, pedunculopontine tegmental nucleus, and rubrospinal tract. Procaine-induced IBAT and rectal temperature increases were dose-dependent, and reproduced reliably from the same injection site of the same animal. Intravenous indomethacin, a prostaglandin H synthase inhibitor, did not affect procaine-induced temperature rise, and propranolol, a beta-blocker, completely blocked it. These results suggest that microinjected procaine exerts its local anesthetic effect and release a tonic inhibition resulting in a disinhibition-induced temperature increase through the enhanced central sympathetic outflow. They support the hypothesis that a bilateral tonic inhibitory mechanism on heat production exists in the lower midbrain.

Adipose Tissue, Brown↗
PubMed1996

High-resolution T2-weighted MR imaging of the inner ear using a long echo-train-length 3D fast spin-echo sequence.

The purpose of this study was to assess the value of a long echo-train-length 3D fast spin-echo (3D-FSE) sequence in visualizing the inner ear structures. Ten normal ears and 50 patient ears were imaged on a 1.5T MR unit using a head coil. Axial high-resolution T2-weighted images of the inner ear and the internal auditory canal (IAC) were obtained in 15 min. In normal ears the reliability of the visualization for the inner ear structures was evaluated on original images and the targeted maximum intensity projection (MIP) images of the labyrinth. In ten normal ears, 3D surface display (3D) images were also created and compared with MIP images. On the original images the cochlear aqueduct, the vessels in the vicinity of the IAC, and more than three branches of the cranial nerves were visualized in the IAC in all the ears. The visibility of the endolympathic duct was 80%. On the MIP images the visibility of the three semicircular canals, anterior and posterior ampulla, and of more than two turns of the cochlea was 100%. The MIP images and 3D images were almost comparable. The visibility of the endolymphatic duct was 80% in normal ears and 0% in the affected ears of the patients with Meniere's disease (p < 0.01). In one patient ear a small intracanalicular tumor was depicted clearly. In conclusion, the long echo train length T2-weighted 3D-FSE sequence enables the detailed visualization of the tiny structures of the inner ear and the IAC within a clinically acceptable scan time. Furthermore, obtaining a high contrast between the soft/bony tissue and the cerebrospinal/endolymph/ perilymph fluid would be of significant value in the diagnosis of the pathologic conditions around the labyrinth and the IAC.

Adult↗
PubMed1996

Coexistence of choriocarcinoma and adenocarcinoma in the rectum: molecular aspects.

Choriocarcinoma, a malignant tumor of usually placental origin, in divided into two groups; the gestational and non-gestational types, the latter being rare. Non-gestational choriocarcinoma occurs in the lung, mediastinum, kidney, stomach, and small intestine, but rarely appears in the large intestine. We treated a 29-year-old woman with choriocarcinoma of the rectum with adenocarcinoma. Despite the rarity of the condition and the obscurity of the histogenesis, reports of similar cases and the occurrence of the tumors in the digestive tract suggest that the condition constitutes a clinical entity of a digestive tumor.

Adenocarcinoma↗
PubMed1996

Effect of AV3V lesions on Fos expression and cell size increases in magnocellular neurons of the rat hypothalamus during chronic dehydration.

The effects of osmotic stimulation on Fos expression and cell size increase in the supraoptic nucleus were evaluated in intact, sham-operated, and AV3V-lesioned rats. Fos-positive neurons were found mainly in the AV3V regions and the hypothalamic magnocellular neurons in the forebrain in dehydrated intact rats. Intraperitoneal injection of hypertonic saline and chronic dehydration induced a significant increase in number of Fos-positive neurons in the supraoptic nucleus of intact and sham-operated rats. AV3V lesions completely abolished the expression of Fos in SON neurons of rats that were intraperitoneally injected with hypertonic saline and were chronically dehydrated. Chronic dehydration increased significantly cell size of the OXT and AVP magnocelluar neurons in intact and sham-operated rats. However, there was no increase in cell size of those in the AV3V-lesioned rats. These results demonstrate that neural input derived from AV3V regions plays a significant role in causing Fos expression and structural changes such as cell size increase in the hypothalamic magnocellular neurons with osmotic stimulation.

Animals↗
PubMed1996

Papillary and follicular thyroid carcinoma: the treatment results of 357 patients at the National Kyushu Cancer Centre of Japan.

During the period from April 1974 to March 1993, 357 patients received surgical treatment for papillary and follicular carcinoma of the thyroid gland at the Department of Head and Neck Surgery of National Kyushu Cancer Centre, Japan. In this paper, we review the various clinico-pathological features of these patients and analyse their influence on patient survival. While the majority of the patients' ages ranged from the third through seventh decade, only the patients older than 40 years old died. In papillary carcinomas, there was a statistically significant difference in the survival rate between younger (less than 45 years old) and older (45 years of age or older) patients. The rate of patients who died of thyroid cancer also increased in the cases with extra-thyroidal tumour invasion, and metastasis to distant organs. A multivariate analysis also showed that the age, extrathyroidal invasion and distant metastasis are significant prognostic factors. However, sex, histology and lymph node metastasis were not prognostic factors for survival.

Adenocarcinoma, Follicular↗
PubMed1996

D-type cyclin expression is decreased and p21 and p27 CDK inhibitor expression is increased when tsBN462 CCG1/TAFII250 mutant cells arrest in G1 at the restrictive temperature.

BACKGROUND: The tsBN462 temperature-sensitive mutant hamster cell line exhibits cell cycle arrest and apoptosis at the restrictive temperature of 39.5 degrees C, due to a point mutation in the CCG1/TAFII250 gene, which encodes a component of the general transcription factor TFIID. RESULTS: We now report that CCG1/TAFII250 persisted as a complex with TBP and associated proteins (TAFs) in tsBN462 cells at the restrictive temperature. FACScan analysis revealed that the tsBN462 mutation resulted in a failure to progress out of G0 into G1. Using two-dimensional gel electrophoresis we observed a decrease in the synthesis of several proteins, starting in the middle of the G1 phase, becoming very pronounced during late G1. The expression of the immediate early genes c-fos, c-jun and c-myc was normally induced by serum treatment of quiescent cells at the restrictive temperature, whereas expression of cyclins A, D1 and D3 was reduced. Expression of the cyclin-dependent kinase (CDK) inhibitor proteins p21 and p27 was enhanced. Consistent with the decreased cyclin D and increased p21/p27 expression, we found that phosphorylation of Rb was decreased at 39.5 degrees C. Cyclin A-, E- and Cdk2-associated histone H1 kinase activity was reduced concomitantly with the increase in p21 protein. CONCLUSION: Decreased cyclin/Cdk kinase activity and decreased Rb phosphorylation are possible causes of G1 cell cycle arrest in tsBN462 cells at the restrictive temperature.

Animals↗
PubMed1996

Synthesis of secretory protein in regenerating liver of rat after partial hepatectomy.

Albumin immunoreactivity in the liver was examined on days 2, 5 and 10 after two-thirds partial hepatectomy by light and ultrastructural immunoperoxidase methods and the ultrastructural area of the rough endoplasmic reticulum (ER) in hepatocytes was measured. Albumin immunoreactivity was seen in the rough ER and Golgi apparatus of all hepatocytes in the hepatectomized liver and ultrastructural analysis showed a significantly greater area of rough ER on day 5 than on days 2 or 10. Albumin mRNA was studied by the in situ hybridization technique using radioisotopes and their numbers were determined visually. Albumin mRNA was present as grains in all hepatocytes and the grains varied in number during regeneration of the liver, being more abundant on day 5 than on days 2 or 10. The activity of [3H]-leucine incorporated into albumin synthesis, an indicator of translational activity, was higher on days 5 and 10 than on day 2 and was highest on day 5. In conclusion, albumin synthesis varied during liver regeneration after partial hepatectomy, being reduced at the peak of cell proliferation on day 2 and being most active on day 5.

Albumins↗
PubMed1996

Inhibitors of cytochrome P-450 augment fever induced by interleukin-1 beta.

Metabolites of cytochrome P-450 are produced in cells when arachidonic acid cascade is activated. Fever genesis depends largely on the cyclooxygenase branch of arachidonic acid cascade, which is caused by many stimuli, such as interleukin (IL)-1, IL-6, and interferon-alpha. To assess the significance of cytochrome P-450 branch in fever, murine recombinant IL-1 beta was bilaterally microinjected (1 ng/microliter) into the medial preoptic area and anterior hypothalamus in conscious rats treated 60 min previously with or without the cytochrome P-450 inhibitor econazole (15 mg/kg im). The IL-1 beta-induced rise in colonic temperature was enhanced after the plateau phase of fever (from 240 min after IL-1 beta) in econazole-pretreated rats (P < 0.001). Another cytochrome P-450 inhibitor, clotrimazole (15 mg/kg im), also enhanced IL-1 beta-induced fever from 160 min after IL-1 beta injection (P < 0.001). Econazole also enhanced the fever when it was given 120 min before injection of IL-1 beta (P < 0.001). The cytochrome P-450 inhibitor, however, did not affect the fever when given 10 min after IL-1 beta (P = 0.95). Econazole and clotrimazole did not alter normal body temperature (P = 0.65 and 0.73, respectively). The results suggest that the metabolite(s) of cytochrome P-450 affect the falling phase after the plateau phase of fever and act as putative endogenous antipyretic(s).

Animals↗
PubMed1996

Measurement of PO2 in liver using EPR oximetry.

With the use of India ink and lithium phthalocyanine (LiPc) as electron paramagnetic resonance (EPR) oximetry probes, the PO2 of the liver was investigated in mice. Because India ink was taken up by the Kupffer cells of the liver, the EPR signal of the India ink reflected the average PO2 in phagocytic vesicles of these cells. The mean value of PO2 in the Kupffer cells measured by India ink was 15.3 +/- 4.4 Torr in unanesthetized animals. LiPc was administered as a macroscopic crystal and therefore reflected the PO2 of the overall liver. The PO2 measured by LiPc was 23.4 +/- 4.4 Torr, which is consistent with the median value of 23.5 Torr reported previously with the use of an oxygen electrode. Anesthesia (injection of 60 mg/kg ip pentobarbital sodium) decreased the average PO2 in both Kupffer cells and the overall liver. The effects of perturbing the blood flow were studied by reversible blockage of the portal vein and hepatic artery in anesthetized mice; the PO2 in both Kupffer cells (measured with India ink) and in overall liver (measured with LiPc) decreased with obstruction of the blood flow and returned toward normal with reperfusion. These results indicate that the PO2 in different locations in the liver can be significantly different under both normal conditions and after perturbation by either anesthesia or ischemia. These results also demonstrate that EPR oximetry can provide sensitive measurements of PO2 in the liver in vivo under various conditions.

Anesthesia↗
PubMed1996

Sialolithiasis in children: report of four cases.

Sialolithiasis in children is rare. Four cases of sialolithiasis in the submandibular gland occurring in children < or = 10 years old are reported. True and distal oblique occlusal radiographs were found to be useful for detection of the sialolith. A review of the literature on sialolithiasis in children is presented.

Child↗
PubMed1996

Hypertrophy of oxytocinergic magnocellular neurons in the hypothalamic supraoptic nucleus from gestation to lactation.

In the present experiments, we examined the changes in cell size (profile area) of oxytocinergic magnocellular neurons during reproductive states and dehydration with quantitative immunohistochemistry. During lactation, hypertrophy was observed in oxytocinergic magnocellular neurons but not in vasopressinergic ones in the supraoptic nucleus. In virgin rats, chronic dehydration increased the cell size in both oxytocinergic and vasopressinergic neurons. After normal weaning time, the cell size decreased, returning to virgin level within 20 days. However, if the mothers were deprived of their litters immediately after parturition, the cell size rapidly returned to virgin level within 5 days. Furthermore, the increase in the cell size of the mothers was not affected by the size of their nursing litters.

Animals↗
PubMed1996

Effect of increased middle ear pressure on blood flow to the middle ear, inner ear and facial nerve in guinea pigs.

We investigated the effect of increased middle ear pressure on blood flow to the inner ear, middle ear, and facial nerve in guinea pigs using a nonradioactive microsphere technique. The elevation of middle ear pressure significantly reduced blood flow to the middle ear. Blood flow to the facial nerve also decreased due to the elevation of the middle ear pressure but the reduction was not significant. Blood flow to the inner ear did not change even after the middle ear pressure was increased. Findings are discussed in relationship to aural barotrauma, alternobaric vertigo and facial baroparesis.

Animals↗
PubMed1996

[Combined chemotherapy with MMC, ADM, CDDP, etoposide (VP-16) and 5'-DFUR, (MACVD therapy) as a second-line chemotherapy for metastatic gastric cancer: three cases].

Three patients with chemotherapeutically pretreated metastatic gastric cancer were given MAC-VD therapy combining MMC, ADM, CDDP, Etoposide (VP-16) and 5'-DFUR. All were evaluable for their responses. Patients ranged in age from 49 to 61 years. Performance status scale (P.S.) grade 0 was two cases; and P.S. grade 1 was one case. The overall response rate, CR+PR, was 0+2/3 (66.7%). The response rate in the primary lesions was 0%, against 66.7% (2/3) in the liver, 100% (1/1) in the spleen, 100% (1/1) in the lung, and 0% in the abdominal lymph node metastasis. The chief manifestations of toxicity were hematologic, such as leukocytopenia, anemia and thrombocytopenia in 100% of the cases. Non-hematologic toxicity was seen in alopecia in 66.7%, diarrhea in 33.3%, fever in 33.3%, and pigmentation in 33.3%. Severe toxicity was not observed. From these data, the administration of MAC-VD therapy was considered tolerable and these data suggested that this therapy could be given as a second-line chemotherapy when initial treatment failed to obtain a response after a partial response.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1996

Taurine in the liver. The function of taurine conjugated with bile acids.

1. Taurine had cytoprotective effects on hepatocytes under hyperoxic or hypoxic condition in the presence of Ca2+. 2. Bile acids had toxic effects on hepatocytes; there was no significant difference in the toxicity between free bile acids and taurine-conjugated bile acids. 3. The mobility of the membranes, examined by 31P-NMR, decreased after treatment with taurine or free bile acids, but increased after treatment with taurine-conjugated bile acids. 4. The fluidity of the membranes, measured by ESR, did not change after treatment with taurine, but decreased after treatment with free bile acids and increased after treatment with taurine-conjugated bile acids. In conclusion, because most bile acids are conjugated with taurine in the liver after administration of taurine, the influence of taurine-conjugated bile acids has to be taken into consideration in estimating the functions of taurine in the liver.

Animals↗
PubMed1996

[A case of ureteropelvic junction stenosis accompanied by a valve-like structure in the renal pelvis].

A 9-year-old girl visited our clinic with recurrent high fever as her chief complaint. Her excretory urogram showed only a few dilated upper calyces. Retrograde pyelography revealed ureteropelvic junction stenosis with hydronephrosis, so that the ureteral catheter could not be passed through the ureteropelvic junction. A fold-like filling defect was also seen above the ureteropelvic junction. At operation the ureteropelvic junction was found to be markedly obstructed, and a semilunar valve-like structure was also observed above it. The valve-like structure was seen where the fold-like filling defect appeared on the retrograde pyelogram. En bloc resection of the lower part of the renal pelvis with the valve-like structure and the ureteropelvic junction was performed, followed by dismembered uretero-pyeloplasty. Histologically, the valve-like structure was a transverse mucosal fold with a muscle layer and without adventitia. Many cases of ureteral valves have been reported, but none with valves or valve-like structures within the renal pelvis as in our case.

Child↗