PubMed Health⌕ Search

Biomedical subjects

N Nishikawa

Publications and source records attributed to N Nishikawa.

79 records · Page 5Linked to original sources
PubMed1979

[Inhibition of nociceptive responses of spinal dorsal horn neurons by periaqueductal gray stimulation (author's transl)].

In order to analyze analgesic effects of periaqueductal gray stimulation, experiments were carried out in nitrous oxide anesthetized cats. Spinal dorsal horn neurons receiving C-fiber inputs from the posterior tibial and/or superficial peroneal nerves were excited by noxious heat stimulation of the ipsilateral hindpaw. The evoked spike discharges were inhibited by repetitive stimulation of the periaqueductal gray at currents 300--900 microamperemeter. Effective sites for inhibition were distributed throughout the ventral half of the periaqueductal gray bilaterally. A monotonous relationship was found between stimulus intensity (skin temperature) and number of spike discharges; As predicted by Stevens' law, the number of spike discharges psi grew as a power function: psi = K(psi--psi0)beta where psi is the stimulus intensity, psi0 is the effective threshold, and K is a slope constant of the spike discharges versus stimulus intensity curve depending upon neurons. The exponent beta was approximately 1.0. The periaqueductal gray stimulation resulted in a decrease in the slope constant kappa, without alteration either in the threshold constant psi0 or in the exponent beta.

Action Potentials↗
PubMedDate not supplied

Variability of diastolic paradoxical jet flow in a patient with hypertrophic cardiomyopathy with midventricular obstruction: dissociation between systolic and diastolic intracavitary flow dynamics.

Variability of paradoxical jet flow in a case of hypertrophic cardiomyopathy with midventricular obstruction was examined. Propranolol decreased both peak diastolic paradoxical jet flow velocity and peak systolic velocity at the narrowing portion. Nitroglycerin decreased peak diastolic paradoxical jet flow velocity with an increase in peak systolic velocity at the narrowing portion. Thus the diastolic paradoxical jet flow is dynamic as well as the abnormal systolic flow; however, changes in these abnormal flow dynamics may not be necessarily in the same direction. Doppler echocardiography should be useful in assessing effects of interventions on the flow dynamics in patients with hypertrophic cardiomyopathy with midventricular obstruction.

Adult↗
PubMedDate not supplied

Comparison of predictive value for colorectal cancer in subjects with and without rectal bleeding.

BACKGROUND/AIMS: To clarify the association between a sign of rectal bleeding and colorectal cancer, and to reveal the relationship of rectal bleeding to the results of an immunochemical fecal occult blood test. METHODOLOGY: In a population-based cross sectional study, 30,138 subjects who received immunochemical fecal occult blood screening with a 2-day method were divided into two groups, according to the results of a questionnaire on a sign of rectal bleeding, and the positivity rate of an immunochemical occult blood test as well as the predictive value for colorectal cancer were compared in the two groups. RESULTS: The fecal occult blood test was positive in 8.8% of subjects with rectal bleeding and in 6.0% of subjects without rectal bleeding, and the predictive value was 6.4% and 3.3% in subjects with and without rectal bleeding, respectively, showing a significant difference in the positivity rate (p<0.001) as well as the predictive value (p<0.05) between these two groups. CONCLUSIONS: These findings indicate that there are positive relations between the subjects with rectal bleeding presentation and colorectal cancer, and a sign of rectal bleeding and the results of an immunochemical fecal occult blood test.

Colorectal Neoplasms↗
PubMedDate not supplied

Salivary films on hydroxyapatite studied by an in vitro system for investigating the effect of metal ions and by a quartz-crystal microbalance system for monitoring layer-by-layer film formation.

The salivary film or the acquired pellicle is a protein film formed initially on the enamel surface of teeth. Such a film plays an important role in enamel protection, but is also an initial substructure for the formation of plaque and the cosmetically undesirable colored stain. The composition and the structure of the film are still essentially unknown because of the difficulty of its isolation for characterization. The purpose of this study was to investigate the effect of some metal cations on the salivary film or the pellicle formation, and also to clarify the mechanism of development. First, using infrared spectroscopy (IR) and X-ray photoelectron spectroscopy (XPS), the in situ-formed film in the mouth was confirmed to contain selectively adsorbed well-known proteins. Then, in vitro studies have demonstrated that Ca2+ ions enhance film formation at the initial stage in virtue of Ca bridging and, interestingly, that Mg2+ ions oppositely inhibit the formation. Furthermore, the quartz-crystal microbalance (QCM), utilized successfully for the first time to study the salivary film, has shown the possibility of an alternate accumulation mechanism by which the surface charges on the film are effectively reversed by the opposite charged proteins.

Durapatite↗