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Biomedical subjects

K Iwata

Publications and source records attributed to K Iwata.

At least 343 records · Page 19Linked to original sources
PubMed1988

Alternative method for calculating right ventricular ejection fraction from first-pass time-activity curves.

Single-beat right ventricular ejection fraction (RVEF) determined using the first-pass method changes with rapid variations in the concentration of radionuclide tracer in the ventricle. Underestimation of single-beat RVEF occurs when radionuclide tracer rapidly enters the ventricle, and overestimation results when the tracer quickly flows out of the ventricle. In order to attenuate this effect, a data processing technique employing the relative "time-volume" curve was proposed. In the present paper, it was assumed that this time-volume curve could be approximated by dividing the original time-activity curve by a gamma variate function representing the time-concentration curve. Each single-beat ejection fraction calculated from the time-volume curve agreed well with the known phantom ejection fraction although the concentration of tracer varied rapidly. This new method was applied to several clinical cases.

Heart↗
PubMed1988

Screening for skin-tumor promoters.

Since attention has been drawn to the role of oxygen radicals in tumor promotion, we investigated whether or not the nitroblue tetrazolium (NBT) reduction test using mouse peritoneal macrophages was useful as a rapid screening method for skin-tumor promoters. On the basis of our results, we concluded that this test system was appropriate for the screening of 12-0-tetradecanoylphorbol-13-acetate (TPA)-type tumor promoters and bore comparison with other screening methods for tumor promoters. A large number of skin-tumor promoters, such as active phorbol esters, teleocidin and aplysiatoxin, appear to act indirectly through a free radical mechanism by binding to a membrane receptor.

Animals↗
PubMed1988

[Continuous intra-arterial infusion chemotherapy for inoperable retroperitoneal liposarcoma--a case report].

A case of an inoperable recurrent retroperitoneal liposarcoma, histologically diagnosed as being a mixed myxoid type and a round cell type, which was treated by continuous intra-arterial infusion chemotherapy, is reported. The authors applied this treatment method using adriamycin and 5-FU via the feeding arteries, i.e., the superior and the inferior mesenteric arteries. The tumor showed remarkable regression with no severe complications, even though general chemotherapy using adriamycin proved to be ineffective. This infusion method was thus evaluated as highly effective.

Adult↗
PubMed1987

Contrast sensitivity and pattern visual evoked potential in patients with glaucoma.

Contrast sensitivity and pattern visual evoked potential (VEP) were measured in cases of ocular hypertension and primary open-angle glaucoma at various stages. The visual field of each eye was examined quantitatively and the retinal nerve fiber layer and optic disc were precisely assessed with magnified stereoscope fundus photography. This study revealed that contrast sensitivity of the eyes with glaucoma was within the normal range in the very early stage of the disease. As optic nerve damage advanced, high- or low-frequency loss developed. Further optic nerve damage produced a level type of loss. Pattern VEPs also showed increasing abnormalities as glaucomatous optic nerve damage progressed. Measurements of contrast sensitivity and pattern VEP were found not to be as sensitive as quantified precise visual field measurement or color stereoscopic fundus photography for detection of minor optic nerve damage in cases of early glaucoma. These methods may be useful, however, as an objective and subjective monitor of progression of optic nerve damage in glaucoma.

Adolescent↗
PubMed1987

Responses of bradykinin sensitive tooth-pulp driven neurons in cat cerebral cortex.

The properties of single cortical neurons responding to electrical stimulation of the tooth-pulp and to intrapulpal application of bradykinin were studied in the cat. The activities of tooth-pulp driven neurons (TPNs) were recorded from the middle and anterior parts of the coronal gyrus of the cerebral cortex. Bradykinin-sensitive tooth-pulp driven neurons (BK-TPNs) were located in layer IV of area 3b of the anterior part of the coronal gyrus. These neurons had a large cutaneous oro-facial receptive field and received a nociceptive input from the facial skin as well as from the tooth-pulp. The BK-TPNs had a higher threshold and longer latency to electrical stimulation than TPNs insensitive to bradykinin (non BK-TPNs). These findings suggest that BK-TPNs in this cortical area may be involved in sensory processing of noxious information from trigeminal regions.

Action Potentials↗
PubMed1987

Monoclonal antibodies to bovine collagenase inhibitor.

Hybridoma antibodies against bovine collagenase inhibitor were produced by fusion of myeloma cells NS-1 (P3-NS1-1) with spleen cells from mice hyperimmunized with collagenase inhibitor purified from the explant medium of bovine dental pulps. Hybridomas positive by an enzyme-linked immunosorbent assay (ELISA) for bovine collagenase inhibitor were cloned by the dilution method. Seventeen hybridomas producing antibodies were isolated, four of which also recognized purified human collagenase inhibitor in the ELISA. Using a monoclonal antibody-Sepharose affinity column, we easily purified both bovine and human collagenase inhibitors to homogeneity. They showed the same mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, corresponding to a molecular mass of 32,000 daltons.

Animals↗
PubMed1987

[A case of gastric carcinoma disappearing after short-term preoperative chemotherapy].

A 58-year-old male visited the Kochi Municipal Central Hospital on May 17, 1984. A barium meal study and endoscopy revealed a huge crater surrounded by a thick embankment on the posterior wall of the stomach body. Biopsy specimens taken from the lesion revealed tubular adenocarcinoma, UFT (600 mg/day) and anti-tuberculous drugs were administered due to the complication of pulmonary tuberculosis. Endoscopic examination on August 6, 1984, revealed a remarkable improvement, showing a shallow irregular depression with converging folds. The patient underwent surgery on August 7, 1984, because from the endoscopic appearance, residual cancer was highly suspect, and also tuberculosis had improved. The histology of the surgically resected specimen showed a chronic peptic ulcer, the base of which was covered with regenerating mucosa. No cancer nests were demonstrated even by serial tissue sections.

Adenocarcinoma↗
PubMed1986

A sandwich immunoassay for human prolyl 4-hydroxylase using monoclonal antibody.

Monoclonal antibody was used in a sandwich enzyme immunoassay and in a radioimmunoassay for human serum immunoreactive prolyl 4-hydroxylase. The enzyme immunoassay utilized a monoclonal antibody as a solid phase and horseradish peroxidase-labeled rabbit antibody (Fab') to human prolyl 4-hydroxylase as a conjugate. Sensitivity was 0.1 ng (0.4 fmol) of enzyme per tube. With a conjugate purified by an enzyme-bound affinity column, sensitivity was increased to 0.01 ng (0.04 fmol) per tube, and linearity was obtained between 0.01 to 30 ng (0.04-125 fmol) per tube. The radioimmunoassay used a 125I-labeled rabbit antibody (IgG) as the conjugate. Sensitivity of this technique was 0.4 ng of enzyme per tube. The enzyme immunoassay gave reproducible quantitation and evidenced a higher enzyme concentration in the serum of patients with liver disorders. Protein immunoblotting showed that the serum immunoreactive prolyl 4-hydroxylase trapped in the sandwich immunoassay was mainly the beta-subunit.

Antibodies, Monoclonal↗
PubMed1986

Cortical cells driven by the low-threshold tooth pulpal afferent in cats.

The input pattern and spatial distribution of tooth pulp-driven neurons (TPNs) in the cat cortex were studied by recording the unitary activities of these neurons. Stimulation was applied to the upper and lower canine and molar tooth pulps. It was possible to record activities of TPNs in the deep layers of the areas 3a and 3b of the coronal gyrus of cerebral cortex. TPNs driven by the ipsilateral tooth pulp stimulation were distributed more anteroventrally than those driven by contralateral stimulation. Cells driven by bilateral pulp stimulation were situated between these two neurons. The threshold intensity for TPNs in the area 3a was lower than that for neurons in 3b. The majority of TPNs in the area 3a of the anterior part of the coronal gyrus received inputs from low-threshold masseteric muscular afferents as well as from tooth pulp afferents. The findings suggest that TPNs in the area 3a may have a relation to orofacial motor functions.

Animals↗