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Biomedical subjects

T Nishikawa

Publications and source records attributed to T Nishikawa.

At least 19 recordsLinked to original sources
PubMed1992

Determination of free amino acid enantiomers in rat brain and serum by high-performance liquid chromatography after derivatization with N-tert.-butyloxycarbonyl-L-cysteine and o-phthaldialdehyde.

The concurrent determination of free amino acid enantiomers and non-chiral amino acids in rat brain and serum was accomplished by high-performance liquid chromatography with fluorimetric detection after derivatization with N-tert.-butyloxycarbonyl-L-cysteine and o-phthaldialdehyde. The method revealed the presence of a large amount of free D-serine (0.22 mumol/g of tissue; D/D + L ratio = 0.25) in the brain whereas D-aspartate and D-alanine were established to be at trace levels. These results further support the presence of D-serine in adult brain tissues as demonstrated by recent work using gas chromatography.

Amino Acids↗
PubMed1992

Extensive en bloc resection of regionally recurrent carcinoma of the rectum.

To remove regionally recurrent cancer of the rectum completely, more radical extensive resections were attempted than the conventional ones in 35 patients. Twenty-two patients underwent total pelvic exenteration. In 23, sacral resection was done, combined with other procedures including excision of the entire circumference of the lower pelvic ring. There were two hospital deaths. Delayed wound healing was seen in ten. Preoperative severe pain was alleviated in 18. Also, perineal ulcer, vaginal bleeding, bloody stools, and tenesmus disappeared. Of the four 5-year survivors (estimated rate, 23%), only one was disease-free. A second recurrence was seen in 27 patients, of whom 23 had regional failure. It was concluded that so-called local recurrence is a lesion more widespread than indicated by imaging and biopsy. Therefore, even the most radical resection rarely can cure this disease. However, such a surgical procedure can afford more effective palliation than other treatments and may prolong life in selected patients significantly.

Adenocarcinoma↗
PubMed1992

Eating and drinking cause increased dopamine release in the nucleus accumbens and ventral tegmental area in the rat: measurement by in vivo microdialysis.

Dopamine (DA) release was simultaneously monitored in the nucleus accumbens (NAC) and ventral tegmental area (VTA) of conscious rats using in vivo microdialysis. During dialysis perfusion, rats were allowed access to food or water for 20 min following a 36 h food and water deprivation period. DA release increased significantly in the NAC and VTA in response to eating and drinking. The increases in both regions continued until 20-60 min after the end of the feeding or drinking session. These results show that the mesolimbic DA pathway is activated in response to ingestive behavior, and that DA release occurs in the cell body (A10) region as well as in the mesolimbic DA nerve terminals.

Animals↗
PubMed1992

The presence of free D-serine in rat brain.

Free amino acid enantiomers in adult rat brain extracts were analyzed as their N,O-pentafluoropropionyl isopropyl derivatives by gas chromatography on a capillary column of Chirasil-L-Val. A peak X, which exhibited the same retention time as the N,O-pentafluoropropionyl isopropyl derivative of authentic D-serine, was detected in the brain extracts. Electron impact and positive chemical ionization mass spectra of the peak X of the brain extracts were identical to those of authentic D-serine. The concentration of free D-serine and the ratio of D-serine/total serine in the brain were estimated to be 0.27 and 0.23 mumol/g of wet weight, respectively. These data provide the first evidence that substantial quantities of free D-serine are present in mammalian brain tissues.

Animals↗
PubMed1992

High resolution-separation of DNA bands by electrophoresis with a long gel in a fluorescence-detection DNA sequencer.

A high-resolution separation of DNA bands is achieved by electrophoresis with a long gel in DNA base sequencing using fluorescence detection. We separate 760 and 761 base DNA fragments using the 93 cm migration electrophoresis optimized for the separation of DNA bands. A T7 DNA polymerase and an Mn++ buffer are used in sequencing reactions to obtain fluorescence peaks of uniform strength, and the peak areas in the spectrum are used for recognizing the peak number in a cluster of successive peaks. This method is successfully applied to the DNA fragment spectrum obtained by 93 cm migration electrophoresis, which results in a single-band differentiation of bands of 1040 base DNA.

Base Sequence↗
PubMed1992

A YIGSR-containing novel mutein without the detrimental effect of human TNF-alpha of enhancing experimental pulmonary metastasis.

The injection of B16F10 melanoma cells with recombinant human tumor necrosis factor alpha (TNF-alpha) into the tail vein of C57BL/6 mice resulted in 2- to 25-fold more metastatic foci in the lungs than the injection of tumor cells alone. Clearly, TNF-alpha significantly enhanced experimental tumor metastasis. Furthermore, it enhanced the metastasis of Lewis lung carcinoma cells. In contrast, a mutein of TNF-alpha, designated as F4236, having the cell-adhesive sequence (Tyr-Ile-Gly-Ser-Arg) at the N-terminus of the TNF molecule did not enhance metastasis, but rather exhibited similar antitumor activity to wild-type TNF-alpha in fibrosarcoma-bearing mice.

Amino Acid Sequence↗
PubMed1992

Cryofixed, freeze-dried and paraffin-embedded skin enables successful immunohistochemical staining of skin basement membrane antigens.

Conventional chemical fixation and paraffin-embedding procedures give good preservation of morphology, although the antigenicity of many proteins in the tissue sample is destroyed. On the other hand, fresh frozen sections can preserve the antigenicity, but provide poor morphological preservation. To overcome this dilemma, cryofixation and freeze drying were used on human skin tissue, applying methodology which has only been used to study lymphoid tissue. First, fresh human skin was cryofixed in liquid isopentane (-160 degrees C) cooled by liquid nitrogen. The skin was then freeze-dried at -40 degrees C and 10(-2) atmospheric pressure for 72 h, followed by embedding in paraffin. Sections 4 microns thick taken from this cryofixed, freeze-dried, and paraffin-embedded skin were stained with hematoxylin-eosin or used for immunolabeling with antibodies against basement membrane antigen, including type IV and type VII collagen, bullous pemphigoid antigen, epidermolysis bullosa acquisita antigen, and GB3 antigen. The morphological preservation of these sections was as good as that of routine formalin-fixed and paraffin-embedded skin sections. The basement membrane was clearly immunostained with all antibodies used, and the intensity of the reaction was as strong as that seen in frozen sections. Evaluation of antigen distribution in conjunction with the detailed skin structure was therefore possible in the same sections.

Antibodies, Monoclonal↗
PubMed1992

A case of pediatric cardiomyopathy with severely restrictive physiology.

A rare case of a 6-year-old male with idiopathic familial cardiomyopathy manifesting severely restrictive physiology is reported. The patient showed congestive heart failure with dilatation of both atria with a normal ventricular cavity. A square-root configuration was revealed in the ventricular pressure tracings. His elder brother had died of hypertrophic cardiomyopathy at the age of 3 years. Endomyocardial biopsy disclosed marked disorganization of muscle bundles with hypertrophy of the myocytes and interstitial fibrosis. The patient died suddenly during hospitalization. Autopsy revealed diffuse hypertrophy of both the ventricular walls and the ventricular septum with extensive myocardial disorganization and interstitial fibrosis. These advanced myopathic changes in the myocardium may have been related to the restrictive physiology in this case.

Bundle-Branch Block↗
PubMed1992

Modulation of cerebral acetylcholine metabolism by the dorsal diencephalic conduction system in the rat.

We investigated the effects of interruption of the impulse flow in the habenulopeduncular pathways by local infusion of tetrodotoxin on the acetylcholine and choline content in selected dopamine rich regions in the forebrain and midbrain in rats. The tetrodotoxin infusion caused a marked increase in acetylcholine content in the medial frontal cortex, striatum and ventral tegmental area+interpenduncular nucleus, but not in the limbic area or the substantia nigra, whereas choline content was reduced only in both the striatum and ventral tegmental area+interpeduncular nucleus. There was an increase in 3,4-dihydroxyphenylacetic acid content in the striatum after the manipulation. These findings suggest that the dorsal diencephalic conduction system may be involved in the integration of the activity of cholinergic neurons in the forebrain and midbrain regions and striatal dopanine neurons may play a role in the modulation of cholinergic neurons.

Acetylcholine↗
PubMed1992

Association of ras p21 with differentiation of epidermal keratinocytes in proliferating skin diseases.

We examined the localization of DNA replicating cells and ras oncogene product p21 positive cells in proliferating skin diseases, such as psoriasis vulgaris, lichen planus, verruca vulgaris, verruca plana juvenilis and seborrheic keratosis. ras p21-positive cells were found rather in the differentiated layers than in the proliferating layers of the epidermis. We indicate that the expression of ras p21 can be associated with the differentiation of epidermal keratinocytes not only in tumor tissues but also in inflammatory skin disease.

Cell Differentiation↗
PubMed1992

Histopathological prediction of liver metastasis after curative resection of colorectal cancer.

To estimate the risk of liver metastasis after curative resection of colorectal cancer, resected specimens from 290 patients (45 with metachronous liver metastasis) were examined and the relationships between 10 histopathological variables and liver metastasis were analysed using our application of the Akaike information criterion (AIC). Of the 10 variables examined, the depth of venous invasion (Vd) had the greatest prognostic value for metastasis, followed by the number of venous invasions, the number of lymphovascular invasions, lymph node metastasis and type of infiltration. The prediction of liver metastasis was further improved by combining Vd with lymphocyte infiltration, mucinous production, interstitial fibrosis or depth of penetration, although these four variables per se were minimally informative for metastasis. We conclude that the prediction of liver metastasis is best achieved by combining Vd with other variables. Our risk group classification, and the estimated probability of liver metastasis for each group, are shown.

Adenocarcinoma↗