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Biomedical subjects

Y Hayasaka

Publications and source records attributed to Y Hayasaka.

At least 37 records · Page 2Linked to original sources
PubMed1999

Benign pleomorphic adenoma arising from the palpebral lobe of the lacrimal gland associated with elevated intraocular pressure.

A 46-year-old man complained of a painless mass in the left upper eyelid. At age 51 years, the patient complained of dull pain in the left eye and diplopia. His left intraocular pressure had increased to 33 mm Hg. No proptosis was noted. The nontender mass in the eyelid was palpable. Computed tomography showed a mass anterior to the orbital rim compressing the globe. The lesion was removed en bloc by a transconjunctival approach. Histopathologic examination of the excised mass showed myxomatous stroma and highly cellular epithelial areas. Postoperatively, the left intraocular pressure normalized. To our knowledge, benign pleomorphic adenomas arising from the palpebral lobe of the lacrimal gland associated with elevated intraocular pressure, as demonstrated in our patient, may be rare.

Adenoma, Pleomorphic↗
PubMed1999

Hypofluorescent spots on indocyanine green angiography at the recovery stage in multiple evanescent white dot syndrome.

PURPOSE: To evaluate the fundus lesions in a young woman. METHODS: Visual function, ophthalmoscopy, electrophysiology, fluorescein angiography, and indocyanine green angiography were performed. RESULTS: A 24-year-old woman had decreased visual acuity (0.2), granularity in the macula, and multiple yellow-white patches in the fundus, reduced a wave on electroretinography, hyperfluorescence on fluorescein angiography, and hypofluorescence on indocyanine green angiography in the left eye. When visual acuity improved to 1.0, the white dots disappeared ophthalmoscopically, and fluorescein angiography showed normal findings. Hypofluorescent spots were found, however, on indocyanine green angiography. CONCLUSION: It is possible that signs of multiple evanescent white dot syndrome may remain longer during examination by indocyanine green angiography than by visual function, ophthalmoscopy, or fluorescein angiography.

Adult↗
PubMed1996

Status of microchimerism in recipients 15 years after living related kidney transplantation.

To study the relevance of microchimerism to the long-term outcome of renal allografting, we analyzed the frequency of microchimerism in kidney transplant recipients who had stable graft function for 15 years or longer. Among the 104 recipients who underwent kidney transplantation between 1971 and 1980, 27 renal allografts (26%) are still functioning. Among these 27 patients, 13 recipients whose donor was still alive and cooperative were investigated for the presence of microchimerism in the peripheral blood and for their immunological status. Microchimerism was tested using the polymerase chain reaction (PCR)-single-strand conformation polymorphism (SSCP) method. To test the sensitivity of PCP-SSCP, the peripheral blood obtained within 5 weeks after transplantation (four kidney transplants, three liver transplants) was also examined. Microchimerism was detectable in five patients within 5 weeks of transplantation (kidney transplantation, 3/4; liver transplantation 2/3. However, in the patients studied 15 years after transplantation, microchimerism was detected in only one recipient (1/13). In this chimeric patient, mixed lymphocyte response revealed high responsiveness against donor antigen. In contrast, some patients who did not have chimerism showed donor-specific hyporesponsiveness in mixed lymphocyte response assay and did not develop antidonor antibody, according to flow cytometric analysis. Microchimerism is an infrequent state in the long-term survivors of kidney allografting, and this state is irrelevant to donor-specific unresponsiveness.

Adult↗
PubMed1995

The effect of total blood exchange with PHP solution on cardiac xenotransplantation.

Prevention of hyperacute rejection is a difficult and unsolved problem in xenotransplantation. Natural antibodies and complement activation have been known to play an important role in the xenotransplantation between discordant species pairs. In the present study, total blood exchange (TBE) was performed with pyridoxalated-hemoglobin-polyoxyethylene conjugate (PHP) solution (Ajinomoto Co., Inc., Kawasaki, Japan) before cardiac xenotransplantation in order to remove the immunoglobulins and prolong xenograft survival time. Guinea pigs and rats were used as the discordant species combination for donor and recipient. Two groups were established: Group 1, untreated control (n = 8) and Group 2, TBT with PHP solution (n = 8). The exchange blood transfusion was carried out at the rate of 15-20 ml/h utilizing PHP solution using a blood pump. After the blood exchange was processed, hematocrit (Ht) levels dropped to 4 or 5%, and a cardiac xenotransplantation was performed within 24 h. The levels of serum IgA, IgM, and IgG were decreased to less than 25, 25, and 10% of the base line, respectively, after blood exchange. A mean xenograft survival time in Group 2 was prolonged to 472 +/- 74 min and to 10.4 +/- 1.8 min in Group 1 (p < 0.01). A titer of the anti-guinea pig lymphocytotoxic antibody in rat serum was decreased to almost nil. The data from this study suggest that total blood exchange with PHP solution may be useful in preoperative removal of xenograft antibodies in xenotransplantation.

Animals↗
PubMed1995

Accumulation of phosphatydilcholine-hydroperoxide in dialysis patients with diabetic nephropathy.

Plasma lipid peroxidation in noninsulin dependent diabetes mellitus (DM) patients were evaluated in DM patients undergoing hemodialysis (HD) by means of a chemiluminescence-HPLC for the specific determination of phosphatidylcholine hydroperoxide (PCOOH). Thirty-three uremic patients with DM nephropathy, undergoing 12 hours HD a week using polymethylmethacrylate membrane, were studied. Of them 22 DM patients on HD were divided into 2 age and sex matched groups treated and conventional group in order to clarify therapeutic effect of 500 mg alfa-tocopherol and 600 mg probucol daily. Fifty DM patients without end-stage renal disease (ESRD) who were age-, period of diabetes-, and sex-matched, were selected as positive control of the subjects. Plasma PCOOH levels were significantly elevated in both DM patients, while the plasma PCOOH in normal controls were 227.0 +/- 68.7 pmol/ml. Plasma PCOOH levels of DM patients undergoing HD were significantly higher than that of patients without ESRD (1,330.8 +/- 642.7 pmol/ml vs. 756.6 +/- 431.9 pmol/ml, p < 0.025). Partial correlation coefficient of plasma PCOOH level demonstrated PCOOH and period of HD in DM patients were highly significantly positively correlated (p < 0.01), although single session of HD was not found to produce significantly increased lipid-peroxidation. Plasma PCOOH roughly remained within similar levels as base lines by medication with anti-oxidant compared to that of conventional group. From these results we conclude that HD intensifies lipid peroxidation and such accumulation of hydroperoxide could account for accelerated progress of atherosclerosis in DM patients with renal insufficiency. It is worthwhile to try an administration of free radical scavenger in order to reduce PCOOH and slow down the progression of atherosclerotic vascular disease.

Adult↗
PubMed1994

Effect of deoxyspergualin on vascular rejection in canine kidney transplantation.

Deoxyspergualin (DSG), an analogue of spergualin produced by Bacillus laterosporus, has a strong immunosuppressive effect in various transplantation models. In this study, we investigated the effect of DSG on vascular rejection in canine kidney transplantation. To enhance vascular rejection, donor-specific blood transfusion (DST) was carried out on days 28, 21 and 14 preceding kidney transplantation. After DST, the donor kidney was transplanted to the recipient iliac fossa. The recipient animals were divided into five groups: namely, Group 1 (n = 7), no treatment; Group 2 (n = 6), DST only; Group 3 (n = 5), DSG only (treated with DSG intravenously at 1.2 mg./kg./day for the first 3 days after transplantation, 1.0 mg./kg./day for the following 3 days and 0.8 mg./kg./day for the following 8 days); Group 4 (n = 6), DST and DSG treatment (same protocol as Group 3); and Group 5 (n = 5), DST and cyclosporine (CsA) (treated with CsA orally at 10 mg./kg./day for 14 days after transplantation). In Group 2, DST treatment significantly reduced kidney graft survival time (8.6 +/- 2.2 days) compared with Group 1 (14.1 +/- 5.5 days). Despite DST, DSG treatment (Group 4) significantly prolonged graft survival time (29.5 +/- 2.6 days), whereas treatment with CsA (Group 5) did not prolong survival time (14.1 +/- 5.5 days) (Group 4 versus 5, p < 0.01). The onset of rejection was significantly delayed in Group 4 (22.1 +/- 2.7 days) compared with Groups 2 (5.7 +/- 2.4 days) and 5 (13.0 +/- 5.7 days) (p < 0.01). In contrast, the interval between rejection onset and animal death was significantly reduced in Groups 2 (3.0 +/- 0.6 days) and 5 (2.4 +/- 1.0 days) compared with Group 4 (7.3 +/- 1.7 days) (p < 0.01). These findings suggest that DSG successfully prevented humoral-type (accelerated acute-type) rejections. Histologically, nonDST groups (Groups 1 and 3) showed minimum vascular rejection. In contrast, all recipients in Group 2 showed severe vascular rejection, as did 80% of CsA treated-animals (Group 5). Despite DST, however, 84% of DSG treated-animals (Group 4) showed minimal or mild vascular rejection and only 17% had severe rejection (Group 4 versus 5, p < 0.04). These data suggest that both clinically and histologically, DSG has more potent immunosuppressive effects against humoral and vascular rejection than CsA.

Animals↗
PubMed1994

Significant prolongation of guinea pig heart contraction transplanted in rat after removal of anti-xeno-antibodies by whole body rinse-out (WBRO) with hemoglobin solution.

PURPOSE: In order to investigate effectiveness of removal of the anti-xeno- antibodies in xenotransplantation (xeno Tx), WBRO using pyridoxalated-human hemoglobin-polyethyleneglycol conjugate (PHP solution) was performed prior to transplantation (Tx) of a guinea pig heart in a rat. MATERIALS & METHOD: Experiment I. Removal of the immunoglobulins and the anti-guinea pig lymphocytotoxic antibody (ALA) by WBRO. Exchange transfusion with the PHP solution was done in the Tx-expected rats until a hematocrit lowered below 5% (n = 11). Experiment II. Xeno heart Txs. Guinea pig hearts were transplanted into rats without immunosuppressants 1) without (n = 8) or 2) with the WBRO (n = 8). RESULTS: Experiment I. Levels lowered to 14% in IgG, 17% in IgA and 6% in IgM, respectively, to initial values after the WBRO. An ALA titer lowered from 4 X (+) to 1 X (-) after the WBRO. Experiment II. An average heart contraction period was 10.4 +/- 1.8 minutes 1) without the WBRO in contrast to 472.5 +/- 4.8 minutes with the WBRO (p < 0.01). CONCLUSION: WBRO using PHP solution is effective in removal of the anti-xeno-antibodies and consequent prolongation of survival of the xenograft.

Animals↗
PubMed1987

Gas chromatographic-mass spectroscopic characterisation of the psychotomimetic indolealkylamines and their in vivo metabolites.

The use of liquid chromatography with on-line fluorescence detection has formed the basis for the separation, characterisation and quantitation of a number of metabolites of the psychotomimetic indolealkylamines N,N-dimethyltryptamine and 5-methoxy-N,N-dimethyltryptamine formed both in vitro and in vivo. Verification of the identity of metabolites has previously been facilitated by the combined use of a number of analytical techniques including multidimensional liquid chromatography and stop-flow spectroscopic analysis. We now describe the combination of liquid chromatography with gas chromatography-mass spectrometry for the unequivocal verification of a number of structurally characteristic metabolites of the psychotomimetic indolealkylamines.

Animals↗