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Biomedical subjects

Y Hosaka

Publications and source records attributed to Y Hosaka.

At least 19 recordsLinked to original sources
PubMed1999

Experimental vascular graft using small-caliber fascia-wrapped fibrocollagenous tube: short-term evaluation.

This study was undertaken to evaluate the application of autogenous fascia as a framework for a fibrocollagen tube for small-caliber vascular prostheses in Japanese white rabbits (n = 15). The fascia, measuring 10 x 40 mm, was harvested from the dorsal fascia and was carefully wrapped around a silicone rod of 1.5 mm in diameter. Then, the fascia-wrapped silicone rod was implanted into a subcutaneous pocket on the medial thigh. Four weeks later, the fascia-wrapped silicone rod was removed from the subcutaneous pocket. The rod was removed from the material, and the fascia-wrapped fibrocollagen tube was treated to make it antithrombogenic. Subsequently, the 1.5 x 10-mm fascia-wrapped tube was prepared as an arterial conduit. Using microvascular techniques, the tube was interposed into the divided femoral artery. Eleven of 15 grafts maintained patency over the follow-up period and no aneurysmal formation was found at any graft site. Microscopically, there was an ingrowth of endothelium with fibroblast proliferation from each end of the recipient vessel at 2 weeks after interposition; however, no neointima was found to line the center of the conduit. At 5 weeks after interposition, the neointimal growth rate was 70 percent. There was an ingrowth of endothelium with fibroblast proliferation from each end onto the entire internal surface of the conduit at 8 weeks after interposition. Further study is required before any long-term conclusions can be drawn.

Animals↗
PubMed1998

Effect of percutaneous transvenous mitral commissurotomy on postexercise breathlessness as determined by ventilation during recovery from constant workload exercise.

We evaluated the effect of percutaneous transvenous mitral commissurotomy (PTMC) on ventilatory variables and dyspnea during recovery from a 6-minute submaximal constant workload exercise, and showed that the decrease in postexercise ventilation after PTMC was closely related to improvement in postexercise dyspnea after PTMC. Ventilation during recovery from submaximal constant workload exercise is related to postexercise breathlessness and can be used to assess the effectiveness of therapeutic interventions.

Adult↗
PubMed1998

Species specificity of the anticoagulant activity of human urinary soluble thrombomodulin.

The anticoagulant activities of human urinary soluble thrombomodulin (UTM) in blood taken from various species using several anticoagulant assay systems were compared; it was examined which coagulant assay system is appropriate for evaluation of the antithrombotic effects of UTM and how the species specificity of UTM is involved in the mechanisms of action of UTM. When anticoagulant activities were compared using activated partial thromboplastin time (APTT), thromboelastography (TEG), and thrombin generation test (TGT), the effect of UTM was found to be the strongest in humans among various species tested. Among the anticoagulant assays tested, TGT reflecting protein C (PC) activation by UTM, appeared to be more sensitive than APTT and TEG in detection of thrombomodulin activity. In the study of the mechanisms of action of UTM, UTM exhibited nearly the same antithrombin activity against human and rat thrombin; the rate of activation of human PC by thrombin/UTM complex was much higher than that of rat PC. Therefore, the species specificity of the anticoagulant activity of UTM may be attributable to thrombin/UTM-PC interaction, but not to UTM-thrombin interaction. From these results, we concluded that TGT reflecting PC activation by UTM will be a more useful assay than APTT and TEG for estimating the antithrombotic effects of UTM in humans. Furthermore, our findings suggest that UTM will exhibit more potent antithrombotic effects in humans than those in rats by strongly enhancing thrombin-catalyzed PC activation.

Animals↗
PubMed1998

Immunohistochemical study of p21WAF1 and p53 proteins in prostatic cancer and their prognostic significance.

Mutations of p53 tumor suppressor gene occur in a subset of aggressive prostatic carcinomas and are detectable by immunohistochemistry. However, it is uncertain whether p53 overexpression really reflects p53 gene mutation or loss of p53 function. p21WAF1, an inhibitor of cyclin-dependent kinases, is activated by wild-type p53 protein, not by mutant type. Therefore, it is possible that combined analysis of p21WAF1 and p53 proteins aids in determining the functional status of p53 immunostaining. Routinely processed prostatic tissues from 60 patients with prostatic adenocarcinomas were examined by immunohistochemistry for p21WAF1 and p53 expression. As for tissue distribution, p21WAF1 protein was expressed mostly in the luminal layers, in contrast, p53 protein was restricted to the basal layers of benign prostatic glands. In prostatic adenocarcinomas, p21WAF1 protein was more likely to be expressed in well-differentiated areas; in contrast, p53 protein was more likely in poorly differentiated areas in the tumors. The percentage of positive nuclear areas for p21WAF1 and p53 proteins in prostatic adenocarcinomas, assessed by CAS200 computerized image analyzer, were 8.6+/-10% and 16+/-14% (mean+/-SE), respectively. The survival study showed that the p53+/ p21- phenotype showed poorer prognosis than p53+/p21+. Multivariate analysis showed that p21WAF1 expression, clinical stage, and Gleason score were independent prognosticators. In conclusion, p21WAF1 immunohistochemistry is a useful method for interpretation of p53 immunohistochemical results. Combined analysis by p21WAF1 and p53 immunostaining would predict the patient survival more accurately than p53 immunostaining alone.

Adenocarcinoma↗
PubMed1998

Microsurgical training with beads.

To assist beginners in the microsurgical practices of handling instruments and tying knots before using an animal model, the authors suggest the use of colored beads. These beads will diminish eyestrain and secondary fatigue. Also, working with colored beads might be a little more amusing and enjoyable for beginners in learning microsurgical techniques during preliminary studies to achieve the necessary orientation for working under the operating microscope.

Microsurgery↗
PubMed1998

An axial-pattern skin flap in the rat.

An axial-pattern rat skin flap based on the caudal femoral artery is described with orthotopic and heterotopic island flap transfers. Free-tissue transfers could also be carried out based on the common femoral artery. Since the pedicle is very small, instead of selective dye injection, a nonselective dye injection was utilized, elevating a very large island skin flap based on the caudal femoral artery. This flap model can provide an alternative opportunity to study the physiology of skin flaps and for training in the basic principles of plastic surgery, including microsurgical practice, with a more challenging model.

Anastomosis, Surgical↗
PubMed1998

Prefabricated osteomusculocutaneous flaps using calvarial bone: experimental study.

Prefabricated osteomusculocutaneous flaps using free calvarial bone were examined and evaluated in a rat model. The animals were divided into two groups according to prefabrication time: 14 days in Group 1 (n = 10) and 28 days in Group 2 (n = 10). Nine of 10 preparations demonstrated neovascularization in Group 1, and all flaps showed neovascularization in Group 2. One flap was lost in Group 1 as a result of infection. Each group was evaluated histopathologically before the second stage of the experiment. Muscles without atrophy and osteocytes were noted in Group 1; however, Group 2 animals had both muscle atrophy and nonviable bone. The prefabricated osteomusculocutaneous flaps were then transferred as both island and free flaps. Flap viability was assessed on postoperative day 7 by macroscopic observation. Although all flaps survived in the island-flap group, two flaps failed to survive due to technical error in the free-flap group. Neovascularization was clearly evident by 2 weeks in the osteomusculocutaneous flaps; after 4 weeks, complete atrophy of the muscle meant that the flaps could no longer be characterized as osteomusculocutaneous. Clinically, it might be possible to use the outer table alone, in which case both thin skin and bone would be desirable. This study may provide a model for this approach.

Animals↗
PubMed1998

Binding of influenza and paramyxoviruses to Group B Streptococcus with the terminal sialyl-galactose linkage.

Using the virus-binding assay and scanning electron microscopy (SEM), influenza A and B type viruses and two paramyxoviruses, parainfluenza (Sendai) and mumps viruses, were found to bind to Group B Streptococcus (GBS), type Ia and II, with the terminal sialyl-galactose linkage, although some viruses detached during the sample processing for SEM, and mumps virus did not bind to GBSIa. Binding of viruses eluted from GBS at 37 degrees C depended on combination of virus and GBS. The biological significance of these findings is discussed.

Bacterial Capsules↗
PubMed1998

Ultrastructure of murine tumour cell lines defective in MHC class I expression before and after interferon-gamma treatment.

Two tumour cell clones, 6D1 and 4C2 cells, which are defective both in the major histocompatibility gene complex (MHC) class I expression and in the endogenous antigen presentation, are recovered with interferon (IFN)-gamma treatment. The present study describes the ultrastructure of these cells by using scanning and transmission electron microscopy in relation to the effect of IFN-gamma treatment. The general morphology of these cells was found to be similar to each other and comparable to that of a tumour cell clone, 4A1 cells, of the same origin, normal in MHC class I expression; they exhibited a fibroblast-like appearance and had many blebs on all the cell surfaces, with desmosome-like junctions between cells. On IFN-gamma treatment, surface fine blebs appeared less, and mitochondria became more densely stained. Expression of MHC class I molecules on the cell surface was much higher in the IFN-gamma treated 6D1 and 4C2 cells than in untreated cells, when estimated by immunoelectron microscopy. The addition of an epitope peptide to these cells did not enhance the class I expression, which differed from other antigen presentation-defective cells such as RMA-S cells, nor change the cell surface morphology.

Animals↗
PubMed1998

Cranioplasty with neovascularized autogenous calvarial bone.

We have presented two cases of cranioplasty with neovascularized autogenous calvarial bone. A surgical procedure applying the principle of flap prefabrication has been applied to the preservation of autogenous calvarial bone obtained during external cranial decompression. The rectus abdominis muscle flap was elevated. A subcutaneous pocket was prepared for preservation of calvarial bone integrated with the rectus abdominis muscle. The outer cortex of calvarial bone was removed partially by bone chiseling. The muscle flap was attached to the bone graft by means of two holes on the bone by suture. The calvarial bone, grafted onto the rectus abdominis muscle flap, was inserted into the subcutaneous pocket. Several weeks later, the neovascularized calvarial bone flap was dissected along with inferior epigastric pedicle. Cranioplasty was performed using the bone element of the flap. Revascularization was achieved by anastomosing the inferior epigastric vessels to the temporal vessels. The postoperative films demonstrated marked radiolucency at the borders of the flap, although bone scan documented that the flap was vascularized. We speculate that the transferred bony segment was not completely vascularized.

Adult↗
PubMed1998

Human Na(+)-myo-inositol cotransporter gene: alternate splicing generates diverse transcripts.

Na(+)-myo-inositol cotransport activity generally maintains millimolar intracellular concentrations of myo-inositol and specifically promotes transepithelial myo-inositol transport in kidney, intestine, retina, and choroid plexus. Glucose-induced, tissue-specific myo-inositol depletion and impaired Na(+)-myo-inositol cotransport activity are implicated in the pathogenesis of diabetic complications, a process modeled in vitro in cultured human retinal pigment epithelium (RPE) cells. To explore this process at the molecular level, a human RPE cDNA library was screened with a canine Na(+)-dependent myo-inositol cotransporter (SMIT) cDNA. Overlapping cDNAs spanning 3569 nt were cloned. The resulting cDNA sequence contained a 2154-nt open reading frame, 97% identical to the canine SMIT amino acid sequence. Genomic clones containing SMIT exons suggested that the cDNA is derived from at least five exons. Hypertonic stress induced a time-dependent increase, initially in a 16-kb transcript and subsequently in 11.5-, 9.8-, 8.5-, 3.8-, and approximately 1.2-kb SMIT transcripts, that was ascribed to alternate exon splicing using exon-specific probes and direct cDNA sequencing. The human SMIT gene is a complex multiexon transcriptional unit that by alternate exon splicing generates multiple SMIT transcripts that accumulate differentially in response to hypertonic stress.

Alternative Splicing↗
PubMed1998

Morphological analysis of olfactory receptor cells using whole-mount preparations of the rat nasal mucosa.

The distribution and entire shape of olfactory receptor cells were investigated by means of whole-mount preparations of the nasal mucosa. Whole mucosa isolated from the nasal septum of rats was processed, as "a free-floating section", and examined by the avidin-biotin complex (ABC) method using antisera against protein gene product 9.5 (PGP 9.5) and calbindin. Essentially all receptor cells were immunolabeled with the PGP 9.5 antiserum, but only half of PGP 9.5-immunoreactive cells were calbindin-immunoreactive. In the immunostaining of whole-mount preparations, pretreatment of tissues by freeze-thawing and dipping in ethanol and xylene greatly improved the permeability of antibodies. Overview of the nasal septum showed that the dorsal and ventral portions of the rostral olfactory area extended deeply into the respiratory area, making a "semi-lunar" shape. The boundary between the two areas was clearly demarcated, although several receptor cells were scattered in the respiratory area near the boundary. Observation at higher magnification clearly demonstrated that several axons derived from perikarya gathered to form nerve bundles showing a dendritic pattern. Proximal axons close to perikarya displayed beaded structures with intense immunoreactivity. They were electron-microscopically identified as swollen portions of axons which might be formed in association with the axonal flow. The present study showed that whole-mount preparation of the nasal mucosa for immunohistochemistry is a useful tool to analyze the morphology of olfactory receptor cells and axons.

Animals↗
PubMed1998

Thrombomodulin in human plasma contributes to inhibit fibrinolysis through acceleration of thrombin-dependent activation of plasma procarboxypeptidase B.

Thrombomodulin (TM) expressed on endothelial cells binds thrombin and initiates anticoagulant pathways. Soluble functional proteolytic fragments of TM are also present in circulating plasma. Recently, it was reported that TM accelerated thrombin-dependent plasma procarboxypeptidase B (pro-pCPB) activation in a purified system and suggested that TM may inhibit fibrinolysis in crude plasma. The aim of present study was to evaluate any functional role of soluble TM fragments in plasma or purified TM added into plasma to the regulation of coagulation and fibrinolysis. Addition of rabbit TM (1-200 ng/ml) to plasma resulted in a concentration-dependent prolongation of urokinase (UK)- or tissue plasminogen activator (t-PA)-induced clot lysis time. The concentration of TM required for the inhibition of fibrinolysis was lower than that required for the inhibition of coagulation. Addition of anti-rabbit TM IgG or anti-human TM IgG into plasma reduced UK- or t-PA-induced clot lysis time without affecting clotting times, indicating that exogenous TM or soluble TM fragments in normal human plasma participated in regulation of fibrinolysis. Moreover, the TM-dependent inhibition of fibrinolysis was observed only in the presence of thrombin and blocked by addition of carboxypeptidase B inhibitors, but not mediated by protein C activation or direct inhibition of UK, t-PA or plasmin. Analysis of various substrates and inhibitors indicated that TM accelerated thrombin-dependent pro-pCPB activation in plasma. The present results indicate that TM, including soluble TM fragments in plasma, inhibit fibrinolysis via activation of pro-pCPB in plasma.

Animals↗
PubMed1997

Cardiac angiosarcoma responding to multidisciplinary treatment.

Early detection of cardiac angiosarcoma is usually difficult and the prognosis is very poor. We experienced a 32-year-old man with cardiac angiosarcoma who responded to multidisciplinary treatment with recombinant interleukin-2, postoperative chemotherapy (cyclophosphamide, vincristine, doxorubicin, Dacarbazine) and radiation. At 30 months after surgery, there was no evidence of recurrence or metastasis in spite of incomplete resection.

Adult↗