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Biomedical subjects

Y Ichikawa

Publications and source records attributed to Y Ichikawa.

At least 109 records · Page 6Linked to original sources
PubMed2000

Age dependency of neointima formation on vascular prostheses in dogs.

Neointima formed quickly on vascular prostheses implanted in young dogs but not in aged dogs. Previously, we found that impeding neointima formation on vascular prostheses occurred more frequently in aged animals. From these observations, we hypothesized that neointima formation was age-dependent in dogs. To test the hypothesis, 26 fabric Dacron vascular prostheses were analyzed. Half of them were retrieved from aged dogs (more than 13 years old) while the other half were from young ones (less than 1 year old). The grafts were harvested at 8 weeks and 3 months after implantation. The graft surfaces were photographed and analyzed by computer for the ratio of the areas with and without thrombus. Light and scanning electron microscopic observation revealed that most of the thrombus-free areas were lined with endothelial cells. Then the endothelialized areas were calculated. Using data obtained from macroscopic, light microscopic, and scanning electron microscopic observations, the arithmetic means were calculated as the degree of neointima formation. In young animals, the degrees at 8 weeks and at 3 months were 89.1 +/- 8.5% (mean +/- SD) and 95.7 +/- 3.3%, respectively. In old animals, they were 27.9 +/- 5.9% and 31.5 +/- 6. 8%, respectively. From these results, we concluded that neointima formation was age-dependent in dogs.

Aging↗
PubMed2000

Conversion of cellular sialic acid expression from N-acetyl- to N-glycolylneuraminic acid using a synthetic precursor, N-glycolylmannosamine pentaacetate: inhibition of myelin-associated glycoprotein binding to neural cells.

Sialic acids are prominent termini of mammalian glycoconjugates and are key binding determinants for cell-cell recog-nition lectins. Binding of the sialic acid-dependent lectin, myelin-associated glycoprotein (MAG), to nerve cells is implicated in the inhibition of nerve regeneration after injury. Therefore, blocking MAG binding to nerve cell sialoglycoconjugates might enhance nerve regeneration. Previously, we reported that certain sialoglycoconjugates bearing N-acetylneuraminic acid (NeuAc) but not N-glycolylneuraminic acid (NeuGc) support MAG binding (Collins et al., 1997a). We now report highly efficient conversion of sialic acids on living neural cells from exclusively NeuAc to predominantly NeuGc using a novel synthetic metabolic precursor, N-glycolylmannosamine pentaacetate (Man-NGc-PA). When NG108-15 neuroblastoma-glioma hybrid cells, which normally express only NeuAc (and bind to MAG), were cultured in the presence of 1 mM ManNGcPA, they expressed 80-90% of their sialic acid precursor pool as NeuGc within 24 h. Within 5 days, 80% of their ganglioside-associated sialic acids and 70% of their glycoprotein-associated sialic acids were converted to NeuGc. Consistent with this result, treatment of NG108-15 cells with ManNGcPA resulted in nearly complete abrogation of MAG binding. These results demonstrate that ManNGcPA treatment efficiently alters the sialic acid structures on living cells, with a commensurate change in recognition by a physiologically important lectin.

Animals↗
PubMed2000

Artificial ventilation-induced diffuse alveolar damage in rabbits: preliminary study of early detection on expiratory high-resolution computed tomography.

RATIONALE AND OBJECTIVES: To investigate whether expiratory high-resolution computed tomography (HRCT) is more useful than inspiratory HRCT for the detection of early-phase diffuse alveolar damage. METHODS: Eleven anesthetized rabbits were scanned with both inspiratory and expiratory HRCT every 30 minutes during mechanical ventilation. Ten rabbits were killed after the detection of pulmonary abnormalities on both inspiratory and expiratory HRCT. The remaining rabbit was killed when the pulmonary abnormalities appeared only on expiratory HRCT. RESULTS: In four cases (36%), the abnormal findings were detected earlier on expiratory HRCT than on inspiratory HRCT. In seven cases (64%), the abnormalities appeared simultaneously on inspiratory and expiratory HRCT. In all 11 cases, the histopathological changes of areas with abnormal CT findings corresponded to the exudative or proliferative phase of diffuse alveolar damage. CONCLUSIONS: Expiratory HRCT has the potential to detect the abnormalities of diffuse alveolar damage earlier than inspiratory HRCT.

Acute Disease↗
PubMed2000

Malignant transformation of ovarian endometriosis.

One hundred forty-seven cases of ovarian endometriosis, encountered from 1976 to 1999 at Tsukuba University Hospital, were studied to clarify the incidence of malignant transformation. There were 18 cases (12.2%) of atypical endometriosis, among which we found a case (5.6%) of ovarian cancer arising from endometriosis not diagnosed before surgery. This is accounted for 0.7% of all ovarian endometriosis cases. Because the incidence was equal to that of the previous reports, it is most likely that the malignant change in ovarian endometriosis occurred in 0.7% of this disease.

Adult↗
PubMed2000

Stent-graft treatment of type B aortic dissection involving the right aortic arch: case report.

A 56-year-old man suffered from type B aortic dissection associated with the right aortic arch and right descending aorta. The patient was successfully treated by implantation of 2 stent-grafts (a 40-mm Z-stent covered with a 37.5-mm woven Dacron graft) and ligation of the dissected left subclavian artery. A postoperative computed tomographic scan revealed thrombosis of the false lumen and a reduction in the descending aortic diameter.

Aortic Dissection↗
PubMed2000

Effects of dibutyl phthalate as an environmental endocrine disruptor on gonadal sex differentiation of genetic males of the frog Rana rugosa.

To examine the effects of dibutyl phthalate (DBP) on gonadal sex differentiation, genetically male tadpoles of Rana rugosa were exposed to dilute solutions of DBP at concentrations of 0.1, 1, or 10 microM during days 19-23 after fertilization, which is the critical period of gonadal sex differentiation in R. rugosa. Tadpoles were necropsied on day 40. The genetically male tadpoles were produced from crossings between males (ZZ) of one local population, in which females are the heterogametic sex, and females (XX) of another local population, in which males are the heterogametic sex. As positive control groups, tadpoles were exposed to dilute solutions of 17beta-estradiol (E(2)) at concentrations of 0. 01, 0.1, or 1 microM during the same period. The internal structure of the gonads was histologically examined in a total of 30 control tadpoles, 86 E(2)-treated tadpoles, and 90 DBP-treated tadpoles. The gonads of the control tadpoles all showed the typical structure of testes. In contrast, 0.01, 0.1, and 1 microM E(2) treatments caused the undifferentiated gonads of 18, 63, and 100% of the tadpoles, respectively, to develop into gonads of complete or partial ovarian structure. After 0.1, 1, and 10 microM DBP treatment, 0, 7, and 17% of tadpoles, respectively, were similarly affected. These findings suggest that DBP was about 1,000-fold less potent than E(2). Nevertheless, DBP is an environmentally dangerous hormone that disrupts the pathways of testicular differentiation in genetically male animals.

Animals↗
PubMed2000

Persistence of hepatitis B surface antibody levels after vaccination with a recombinant hepatitis B vaccine: a 3-year follow-up study.

We conducted a 3-year follow-up study of 2,008 individuals for the persistence of antibody levels after vaccination with a recombinant hepatitis B vaccine. At 1 month after vaccination had been completed 96.3% of subjects had acquired protective HB surface (HBs) antibody titers on passive hemagglutination assay (PHA) of 2, and 3 years after completion of the vaccination 63.1% had acquired similar titers. The titer decreased below this level after 3 years in 34.5% of subjects who had initially acquired protective antibody titers. The mean acquired HBs antibody titer on PHA was 2 at 1 month and 2 at 3 years after completion of the vaccination. The regression line for these changes was expressed as logY = 1.800-0.24X by the least squares method. The antibody level was estimated to decrease to 2 at 37 months and to seronegativity at 75 months. On the basis of the relationship between PHA antibody titers and the period of their persistence, the persistence of antibody levels after vaccination with a recombinant vaccine can be estimated from the acquired antibody titer determined 1 month after completion of the vaccination, as with plasma-derived vaccines.

Adult↗
PubMed2000

Isolation of morphologically and functionally intact gastric mucosal microvessels rapid communication.

Gastric mucosal microvessels were isolated after arterial perfusion of the rat stomach with magnetized iron oxide suspension. After homogenization of scrapped gastric mucosa, microvessels were initially separated with a high power magnet and further separated and purified by using a nylon sieve. Aliquots of purified microvessels were assessed for viability, histologic appearance, ultrastructure and generation of prostacyclin. Microvessels were plated on Matrigel and cultured in DMEM with high glucose and 10% FBS for 1, 3 or 5 days. After 1, 3 and 5 days of culturing, endothelial viability was assessed with Fast green exclusion, and the basal and stimulated (with calcium ionophore) generation of prostacyclin was determined by assaying aliquots of the incubating medium for 6-keto PGF(1alpha). At 1 and 3 hrs after isolation, microvessels demonstrated intact morphologic structures as reflected by transmission EM and 92+/-4% of viable endothelial cells. The microvessels plated on Matrigel maintained good viability for at least 5 days and generated prostacyclin at the baseline and following ionophore stimulation. These data demonstrate that isolated microvessels cultured under optimal conditions are fully viable and functional.

Animals↗
PubMed2000

Marked increase of trypsin(ogen) in serum of linitis plastica (gastric cancer, borrmann 4) patients.

Linitis plastica, or Borrmann 4 gastric cancer, shows very poor prognosis, and the reason has not been understood. In the present study, we examined serum levels of trypsin(ogen) in 44 gastric cancer patients, including 17 early gastric cancer, 18 non-Borrmann 4 advanced gastric cancer, and 9 Borrmann 4 gastric cancer, by using the RIA gnost Trypsin kit (Hoechst Japan, Tokyo, Japan), which was expected to detect trypsin-1, trypsin-2, trypsinogen-1, and trypsinogen-2 in sera. The trypsin(ogen) concentration was much higher in the patients with linitis plastica than in the other gross types of gastric cancer. Hypertrypsinemia was identified in approximately 60% of advanced gastric cancer cases. Lymph node involvement, liver metastasis, or poorly differentiated adenocarcinoma is an important factor of hypertrypsinemia. The serum trypsin(ogen) level in linitis plastica patients was 3484.4 +/- 2319.7 ng/ml (mean +/- SD), which was significantly higher not only than that of the early gastric cancer (384.1 +/- 92.1) but also the stage IV gastric cancer patients (578 +/- 440.4), excluding those with linitis plastica. The elevated serum trypsinogen level in linitis plastica patients may be related to the malignant behavior of this type of cancer cell. Serum trypsin(ogen) of linitis plastica shows significantly higher concentrations than do the other types of advanced gastric cancer. Therefore, serum concentration of trypsin(ogen) might be a good marker of gastric cancer of linitis plastica.

Humans↗
PubMed2000

[Acute myocardial infarction in elderly patients: medical and social problems].

The number of elderly patients with acute myocardial infarction has been increasing. However, the choice of treatment remains controversial. Medical records of 310 consecutive patients with acute myocardial infarction were reviewed. Two retrospective analyses were performed. 1) Patients were divided into the elderly group(70 years or more) and the younger group(under 70 years). In-hospital course and outcome were compared. 2) Pre-hospital performance status and living status were reviewed in the elderly group. Acute phase reperfusion therapy was performed in fewer patients in the elderly group(60.8% vs 71.9%, p < 0.01). The difference was most pronounced in cases of direct coronary angioplasty(28.6% vs 54.7%, p < 0.05). As a result, the rate of reperfusion success(74.8% vs 86.8%, p < 0.01) was lower in the elderly group. Moreover, the rates of in-hospital death(23.6% vs 6.8%, p < 0.005), pulmonary edema(20.3% vs 10.8%, p < 0.05), cardiogenic shock(11.9% vs 6.0%, p < 0.005), pneumonia(17.3% vs 3.0%, p < 0.005), and delirium(29.4% vs 12.0%, p < 0.001) were higher in the elderly group. Five patients in the elderly group and 3 patients in the younger group required rehabilitation because of worsened performance status. Six of them were non-reperfused patients. Elderly patients considered likely to become bed-ridden because of pre-existing physical disability at admission accounted for 28.9% of the total. Moreover, many elderly patients had poor support systems (8.4% were living alone, 21.0% were living only with their spouse or a child, 30.1% were widows or widowers). These results show that a lower acute phase reperfusion rate(especially angioplasty) resulted in a poor prognosis and worse performance status in elderly patients. Also 30% of patients were not good candidates for conventional treatment because of delirium, and that self-help in daily life is a fundamental goal for most elderly patients. Rapid and simple acute phase reperfusion, subsequent immediate mobilization, and early discharge are recommended for elderly patients with acute myocardial infarction.

Activities of Daily Living↗
PubMed2000

[Clinical evaluation of granisetron hydrochloride for nausea and vomiting induced by oral anticancer drugs].

We investigated the antiemetic effect, safety and usefulness of granisetron hydrochloride tablets on nausea and vomiting induced by oral anticancer drugs used in chemotherapy for gastric cancer and colorectal cancer. In the present trial, oral administration of granisetron hydrochloride was performed during 5 days after nausea or vomiting. 1) Clinically, the effective rate of granisetron hydrochloride (the percentage of cases in which the drug was assessed as "Remarkably effective" or "Effective") was more than 75% on each day of administration. There were no adverse events or abnormal laboratory tests. 2) In terms of usefulness, granisetron hydrochloride was rated "Extremely useful" or "Useful" in 17 out of 23 cases (78.2%). The above results have shown that granisetron hydrochloride tablets, administrated orally once daily at a dose of 2 mg, have an excellent antiemetic effect, and that this is a safe and useful drug.

Administration, Oral↗
PubMed2000

[Peripapillary fluorescein angiographic findings in non-glaucomatous eyes].

PURPOSE: In fluorescein angiography (FAG), glaucomatous eyes show a zone of no fluorescence around the disc and hyperfluorescence indicating serum diffusion at the margin of the zone, which play some role in glaucomatous optic nerve damage. But detailed FAG findings have not been reported in non-glaucomatous eyes. We conducted a study to investigate whether peripapillary FAG findings in glaucomatous eyes were specific to glaucoma or not. MATERIALS AND METHODS: 46 eyes of 46 subjects were selected by some reservations from all the non-glaucomatous patients undergoing FAG in 1996. We studied FAG films and measured the zone of no fluorescence adjacent to the disc (non-fluorescent zone). RESULT: 44 eyes (95.6%) showed a non-fluorescent zone. The non-fluorescent zone was clearly wider in temporal sectors than nasal sectors, and its width was related to the refraction. There were two types of non-fluorescent zone, one showing hyperfluorescence from the outer boundary of the zone in the late phase, and the other showing hyperfluorescence from the disc margin. The width of the non-fluorescent zone in the former type was wider than in the latter type. These results are similar to the findings in glaucomatous eyes. CONCLUSION: These findings suggest that not only glaucomatous eyes but also non-glaucomatous eyes have a variety of histological structures and serum diffusion around the disc.

Adolescent↗