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Biomedical subjects

M Usui

Publications and source records attributed to M Usui.

At least 127 records · Page 7Linked to original sources
PubMed1998

Risk of recurrent subarachnoid hemorrhage after complete obliteration of cerebral aneurysms.

BACKGROUND AND PURPOSE: The neck clipping of cerebral aneurysms is a well-established treatment for subarachnoid hemorrhage (SAH) caused by aneurysmal rupture. However, it is still unclear how great a risk of recurrence patients with a successfully treated aneurysm carry over a long-term period. METHODS: Of 425 patients with SAH surgically treated in Aizu Chuou Hospital from 1976 to 1994, 220 cases meeting the following criteria were studied: (1) all aneurysms detected by 3- or 4-vessel cerebral angiography were clipped, (2) complete obliteration of aneurysm(s) was confirmed by postoperative angiography, and (3) the patient survived >3 years. All patients were traced until January 1998 for recurrent SAH or death. The mean follow-up period was 9.9 (range, 3 to 21) years. RESULTS: Six patients (2.7%) had recurrent SAH, each with an interval ranging from 3 to 17 years (mean, 11 years) since the original treatment. In addition, 2 patients were found to have regrowth of the originally operated aneurysms. The cumulative recurrence rate of SAH, calculated using the Kaplan-Meier method, was 2.2% at 10 years and 9. 0% at 20 years after the original treatment. CONCLUSIONS: The recurrence rate was considerably higher than the previously reported risk of SAH in the normal population, and the rate increased with time. These data indicate that patients with ruptured cerebral aneurysms still carry higher risks for SAH in a long-term period, even after complete obliteration of the aneurysm, and that periodic examination to detect recurrent aneurysms may be indicated for such patients.

Adult↗
PubMed1998

Cytochrome P450 side-chain cleavage enzyme in the cerebellar Purkinje neuron and its neonatal change in rats.

Neurosteroids are de novo synthesized in the nervous system through mechanisms at least partly independent of peripheral steroidogenic glands. However, the concept of neurosteroidogenesis in neurons is not clear in mammalian brains. The present study identified the presence of cytochrome P450scc in the rat Purkinje cell, a typical cerebellar neuron. Immunohistochemical analysis with the antibody against the purified bovine adrenal P450scc showed an immunoreaction restricted to somata and dendrites of the Purkinje cells in adult cerebella. Preadsorbing the antibody with P450scc resulted in a complete absence of the immunoreaction. The antibody against inositol triphosphate receptor, a marker of the Purkinje cell, recognized P450scc-immunoreactive cerebellar cells that showed no immunoreaction with glial fibrillary acidic protein, a specific marker of glial cells. Expression of the P450scc-like protein in the cerebellum was verified by Western blot analysis, and cerebellar P450scc messenger RNA, by RT-PCR analysis in adulthood. On the other hand, P450scc-immunoreactive cells were found to scatter throughout the cerebellum at 0 day of age, before the differentiation of the first Purkinje cells, while the site of expression of this protein was localized only in somata of Purkinje cells at 3 days of age. Immunoreactive dendrites of the Purkinje cell spread into the molecular layer during neonatal development concurrently with its maturation. The intensity of the immunoreaction did not change during neonatal life. Expression of the cerebellar P450scc messenger RNA was also detected after birth, and the level was almost constant during neonatal life. A specific RIA indicated that the pregnenolone concentration was unexpectedly high at 0 day and decreased until 7 days. The total amount of pregnenolone in the cerebellum was almost constant from 0-7 days and increased during 7-21 days concurrently with the cerebellar development. In contrast, the pregnenolone sulfate ester level was low and did not significantly change among the developmental stages. These results suggest that steroidogenic enzyme P450scc appears in the rat Purkinje cell immediately after its differentiation. The expression of this enzyme may remain during neonatal development and in adulthood.

Age Factors↗
PubMed1998

Low-dose basic fibroblast growth factor and vascular endothelial growth factor for angiogenesis in canine acute hindlimb insufficiency.

Basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) have shown strong angiogenetic effects in ischemic animals; however, whether such a beneficial effect could be achieved using low doses remains to be determined. The effects of identical low-level doses of these substances on the creation of collateral circulation in canine acute hind limb insufficiency were evaluated. Anesthetized dogs that had undergone left femoral artery occlusion received 20 microg (2 microg/kg) intravenous boluses of either bFGF or VEGF 3 times at 2-day intervals for the first week only, animals on vehicle saline injection served as controls. All groups, control (n=8), bFGF-treated (n=8), and VEGF-treated (n=6) underwent angiography, blood flow measurement (in ml/min) on the day of ligation (day 0), and at 7, 14 and 28 days, then underwent ischemic limb muscle biopsy at 28 days. Angiogenic-treated groups showed remarkable enhanced collateral circulation at 7 days, which was maintained up to 28 days, and the main collateral source artery of the angiogenic-treated groups dilated by 14 days. Many neovascularized arterioles in specimens of the angiogenic groups were recognized without any tissue edema or necrosis. Even low doses of bFGF or VEGF were enough to augment collateral circulation with no side-effects, and short treatment after acute ischemia was effective. Low-dose bFGF or VEGF may be therapeutical effective options in patients with acute lower limb vascular disease.

Animals↗
PubMed1998

Pain relief after nerve resection for post-traumatic neuralgia.

We performed resection of part of an injured peripheral nerve in 20 patients with post-traumatic neuralgia, after conservative treatment had failed. All had burning pain, paraesthesia and dysaesthesia in the area innervated by the injured nerve. We resected the nerve in the area in which the patient felt pain, and a further 3 cm proximal to the site of injury. In all cases, the local pain disappeared or markedly decreased. The areas of pain relief and of nerve resection coincided completely in 17 patients and partially in three. The results were assessed as excellent by five patients, good by 11, and fair by four. There were no poor results. Histological examination of the resected nerves showed Wallerian degeneration and immunohistochemical tests indicated that substance P, a polypeptide which may contribute to nociceptive transmission, was present in the tissue around the degenerated nerves.

Adult↗
PubMed1998

Autopsy findings in a long-term survivor with glioblastoma multiforme--case report.

Autopsy detected no tumor tissues in a patient who died 6.5 years after the diagnosis of glioblastoma multiforme. A 54-year-old male developed left hemiparesis one month prior to admission. Computed tomography demonstrated a cystic lesion in the right frontal region with irregular ring-like enhancement. The tumor was extensively removed together with the surrounding tissue followed by irradiation (whole brain 32.4 Gy, local 28.8 Gy), and intravenous administration of interferon-beta. Histological examination confirmed the diagnosis of glioblastoma multiforme. He died of accidental head trauma 6.5 years after surgery. Autopsy of the brain detected no evidence of glioblastoma multiforme. The only findings were cerebral edema and hematoma caused by head trauma, as well as histological changes due to radiation damage. This case apparently confirms the histological disappearance of tumor tissue in a long-term survivor with glioblastoma multiforme.

Brain Neoplasms↗
PubMed1998

[Cytomegalovirus retinitis].

Cytomegalovirus (CMV) retinitis is the most common intraocular infection in patients with Acquired immunodeficiency syndrome (AIDS). Approximately 25% of patients with AIDS will develop CMV retinitis during their life time. It is generally associated with CD4+ lymphocyte counts of less than 50 cells/microliter. Clinically, the most characteristic feature of CMV retinitis is a yellow-white lesion of retinal necrosis with a granular border extending into the surrounding retina. At present, ganciclovir and foscarnet have been approved for the treatment of CMV retinitis in patients with AIDS. Although both drugs arrest the progression of retinitis, relapse often occurs. More than ever, ophthalmologists have a special obligation to alleviate both the physical and psychological suffering of patients with CMV retinitis.

AIDS-Related Opportunistic Infections↗
PubMed1998

[Measurement of thrombomodulin values in the serum and eyes of experimental autoimmune uveoretinitis].

Thrombomodulin (TM) is a protein, present on intact endothelial cell surfaces, that plays a major role in the protein C anticoagulant system. Plasma TM is produced by injured endothelium, and is recognized in circulating blood or urine as a sign of endothelium cell damage. The localization of TM within the eye and its kinetics in the eye and the serum were investigated in rats with experimental autoimmune uveoretinitis (EAU). An immuno-histochemical study showed the presence of TM at sites of fibrin in the anterior chamber and retinal vasculitis. The amount of TM in the eye increased with progression of intraocular inflammation, but the serum level of TM did not significantly differ from the values in the control group. These data suggest that TM may play a role in preventing thrombosis in cases of vasculitis and fibrin formation in the anterior chamber in EAU, thus maintaining blood flow and the fluidity of aqueous humor.

Animals↗
PubMed1998

[Cone sensitivity measurements in diabetic retinopathy].

We made cone sensitivity measurements and hue discrimination measurements in 58 eyes of 34 diabetic patients with and without diabetic retinopathy including preproliferative retinopathy. The same measurements were performed in 8 eyes of 8 subjects to compare them. In this study, we were able to make the measurements in a short time and comfortably for the patients because we only needed to measure peak sensitivities of spectral sensitivity curves in three cones. There was significant correlation between short wave length sensitive-cone pathway sensitivity and retinopathy levels determined by fluorescein angiography. The cone sensitivity measurements that we used in this study were simple and sensitive. Our results suggested that the measurements were useful for detection of visual functional disturbances, determination of retinopathy levels, and prognosis.

Adult↗
PubMed1998

[5-S-cysteinyldopa as a tumor marker for primary uveal malignant melanoma].

The clinical significance of 5-S-cysteinyldopa (5-S-CD), a major intermediate in melanin synthesis, was evaluated as a potential diagnostic tumor marker for uveal melanoma. Serum concentrations of 5-S-CD in 6 out of 7 patients with uveal melanoma in the absence of extraocular metastases were close to those of controls. In contrast, serum concentrations of 5-S-CD were found to be elevated in 3 patients with systemic metastases of melanoma. In addition, 5-S-CD in intraocular fluids, including both aqueous and vitreous humor, was elevated in patients with uveal melanoma regardless of the presence or absence of systemic metastases. These results suggest that 5-S-CD in the intraocular fluid may serve as a useful biochemical marker for the diagnosis of uveal melanoma.

Adult↗
PubMed1998

[Association of heat-shock protein and uveitis].

Heat-shock protein 60 derived from Yersinia enterocolitica (Yersinia HSP 60) and bovine retinal HSP (Retina HSP 60) were previously identified by immunological cross-reaction and a high degree of common antigenicity, and a specific antibody against both proteins was detected in the sera of uveitis patients. We report here an attempt to isolate and purify Retina HSP 60 and Yersinia HSP 60. Both Retina HSP 60 and Yersinia HSP 60 showed an enriched content of glycine of approximately 60 to 80%. Lewis rats were inculated with 50 or 100 micrograms of purified Retina or Yersinia HSP 60 emulsified in complete Freund's adjuvant. In 50 to 60% of those inoculated with Retina HSP 60, uveoretinitis was observed about 13 days after inoculation, with massive infiltration of lymphocytes and polymorphonuclear neutrophils in the iris, ciliary body, and retinal tissue. Rats inoculated with Yersinia HSP 60 did not develop ocular inflammation. Lymphocyte proliferation assay was performed to investigate cellular immunoresponses in the rats that developed ocular inflammation after immunization with Retina HSP 60. The results showed significantly higher response to the Retina and Yersinia HSP 60 than to either S-antigen or interphotoreceptor retinoid-binding protein (IRBP), which are known to induce ocular inflammation. Cross-reaction between Retina and Yersinia HSP 60 is suggested. This study suggests that the HSP 60 molecules may be involved in the pathogenesis of intraocular inflammation.

Amino Acids↗
PubMed1998

[Endotoxin and its binding protein in organ failure].

Endotoxin (lipopolysaccharide: LPS) infection due to bacterial translocation is intimately involved in the organ failure that occurs after highly invasive interventions such as extensive liver resection, and has attracted a great deal of interest. LPS that has translocated into portal blood binds to LPS-binding protein (LBP) and is transported to the monocytes and Kupffer cells in liver sinusoids where it is activated through the soluble CD14 that is present on their cell membranes or in blood plasma. Inflammatory cytokines such as TNF-alpha and IL-6 are produced and released by monocytes and Kupffer cells that have been activated by LPS-LBP complexes, and the endothelial cell of the sinusoids is damaged by these inflammatory cytokines. The original anticoagulant function of the damaged endothelial cells is reduced, and microcirculatory insufficiency is caused by the formation of microthrombi. It is important to understand this network mechanism and to prevent invasion, and attention has recently been focused on LBP and CD14 because of this point. The increase in LPS as a result of extensive liver resection, which is highly invasive, begins 3 hours after surgery, and peaks at 6 hours. LBP, however, is awaiting the entry of LPS, principally in the periportal hepatocytes. Its production peaks at 12 hours, and this is related to the excessive production of inflammatory cytokines have been produced, expression of LBP must be suppressed within 12 hours to inhibit this excessive reaction, and that will be the task of a future study.

Acute-Phase Proteins↗
PubMed1997

Regulation of fibrillar collagen gene expression and protein accumulation in volume-overloaded cardiac hypertrophy.

BACKGROUND: Interstitial collagen accumulation has been extensively demonstrated to be increased at both mRNA and protein levels in pressure-overloaded cardiac hypertrophy. However, few data are available regarding the effects of volume overload on myocardial collagens. METHODS AND RESULTS: To determine whether the alterations of collagens may occur in volume-overloaded cardiac hypertrophy, we measured collagen types I and III mRNA levels and protein accumulation in left ventricular (LV) myocardium of rats at 3, 7, and 28 days after the creation of an aortocaval (AC) shunt. Eccentric LV hypertrophy was produced in rats with AC shunting. Northern blot analysis on RNA extracted from LV tissue indicated that the steady state mRNA levels for both type I and III collagen were persistently upregulated in AC shunt rats compared with sham-operated operated control rats. In contrast, the biochemical collagen protein concentration and morphometric collagen volume fraction were comparable between sham-operated control and AC shunt rats at any study time point. Furthermore, the immunohistochemical staining of types I and III collagen and Sirius red staining on myocardial tissue sections revealed no significant alterations in the distribution or density of fibrillar collagens in AC shunt rats. Tissue collagenase activity was not different between control and AC shunt rats after 28 days. CONCLUSIONS: Cardiac volume overload increases LV collagen mRNA as does pressure overload. However, in contrast to pressure-overloaded hypertrophy, the upregulation of collagen transcriptional activity does not result in subsequent myocardial fibrosis in volume-overloaded hypertrophy due to AC shunting. Therefore, the upregulation of collagen gene expression and protein accumulation might be different in pressure-overloaded and volume overloaded hypertrophy.

Animals↗
PubMed1997

Effects of metrifonate on memory impairment and cholinergic dysfunction in rats.

Metrifonate is an organophosphorous compound that has been used in the treatment of schistosomiasis. In this study, we investigated the effects of metrifonate on the impairment of learning and on central cholinergic dysfunction in scopolamine-treated and basal forebrain-lesioned rats. Oral administration of metrifonate (5.0-15.0 mg/kg) ameliorated the scopolamine- and basal forebrain. lesion-induced learning impairment in the water maze and passive avoidance tasks. Metrifonate (50 and 100 mg/kg) also significantly increased extracellular acetylcholine levels but decreased choline levels in the cerebral cortex of the basal forebrain-lesioned rats. The basal forebrain lesion decreased the cholinesterase activity in the cerebral cortex, and metrifonate (100 mg/kg) further reduced the cholinesterase activity. However, cholinesterase inhibition was not observed at the dose that ameliorated learning impairments. These results indicated that metrifonate ameliorated the impairment of learning in both scopolamine-treated and basal forebrain-lesioned rats by not only increasing extracellular acetylcholine levels by inhibiting cholinesterase, but also by undefined other mechanism(s). This finding suggests the usefulness of metrifonate for the therapy of Alzheimer's disease.

Acetylcholine↗
PubMed1997

IFN-gamma-inducing factor (IGIF) is a costimulatory factor on the activation of Th1 but not Th2 cells and exerts its effect independently of IL-12.

We have previously reported the cloning of a novel cytokine, IFN-gamma-inducing factor (IGIF), which shared some biologic activities with IL-12. In this study, we analyzed the effects of murine IGIF on the activation of T cells, and compared the effects with those of IL-12. IGIF alone had no effect on the activation of T cell lines or Th1 clones, while IGIF increased the IFN-gamma production by antigen-stimulated T cell lines, but had no effect on IL-4 or IL-10 production. As reported with IL-12, IGIF served as a costimulatory factor for Th1 clones stimulated with Ag on B cell APC, immobilized anti-CD3, Con A, or IL-2 to augment IFN-gamma production and to induce IL-2R alpha-chain expression and proliferation of the Th1 clones, whereas IGIF had little or no effect on the IL-4 production and proliferation of Th2 clones stimulated with anti-CD3 or Ag. However, IGIF synergized with IL-12 to further augment the IFN-gamma production of the Th1 clones. Even in the presence of saturated amounts of IL-12, IGIF still augmented the IFN-gamma production and proliferation and enhanced the IL-2R alpha-chain expression of the Th1 clones. In contrast with IL-12, IGIF induced IL-2 production by Ag- or anti-CD3-stimulated Th1 clones. These two findings indicate that IGIF and IL-12 are utilizing different signal transduction pathways. We also found that IGIF as well as IL-12 was endogenously released through interaction between Th1 cells and spleen cell APC in the presence of specific Ag, and that it regulated IFN-gamma production. These results further suggest that IGIF may act as an immunoregulatory factor in the immune response.

Animals↗
PubMed1997

Important role of tissue angiotensin-converting enzyme activity in the pathogenesis of coronary vascular and myocardial structural changes induced by long-term blockade of nitric oxide synthesis in rats.

The long-term administration of N(omega)-nitro-L-arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthesis, produces coronary vascular remodeling and myocardial hypertrophy in animals. This study used a rat model to investigate the role of angiotensin I converting enzyme (ACE) in the pathogenesis of such changes. We studied the following groups, all of which received drug treatment in their drinking water: untreated controls, and those administered L-NAME, L-NAME, and an ACE inhibitor (ACEI), and L-NAME and hydralazine. Cardiovascular structural changes and tissue ACE activities were evaluated after the first, fourth, and eighth week of treatment. In rats treated with L-NAME alone, vascular remodeling was evident at the fourth and eighth week, and myocardial hypertrophy was present at the eighth week of treatment. The vascular and myocardial remodeling were characterized by increased tissue ACE activities and immunodetectable ACE in those tissues. These changes were markedly reduced by ACEI, but not by hydralazine treatment. Increased local ACE expression may thus be important in the pathogenesis of cardiovascular remodeling in this model.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

In vivo intravascular laser photodynamic therapy in rabbit atherosclerotic lesions using a lateral direction fiber.

BACKGROUND AND OBJECTIVE: This study was performed to evaluate the possibility of inducing regression of atherosclerotic foci by photodynamic therapy (PDT) using hematoporphyrin derivative (HpD). STUDY DESIGN/MATERIALS AND METHODS: Atherosclerotic rabbits were divided into four groups: A (n = 6) and C (n = 6) were given 5 mg/kg of HpD intravenously; Groups B (n = 4) and D (n = 4) were not. Twenty-four hours after HpD administration, the aortae of groups A and B were exposed to 200 mw output argon dye laser beam at 630 nm for 10 minutes; groups C and D were exposed to 400 mw for 5 minutes. Three rabbits from groups A and C and two rabbits from groups B and D were sacrificed immediately after laser photoradiation, being named groups A 0, C 0 and groups B 0, D 0, respectively. Groups A 7, C 7, and Groups B 7, D 7 were sacrificed 7 days after the photoradiation. RESULTS: In groups A 7 and C 7, most intimal cells and endothelial cells had become necrotic and disappeared, and a loss of intima was observed. No such changes were found in groups B 7, D 7. CONCLUSION: The above data suggest that PDT caused effective regression of the atherosclerotic lesions.

Animals↗
PubMed1997

Prevention of experimental autoimmune uveoretinitis by monoclonal antibody to interleukin-12.

Experimental autoimmune uveoretinitis (EAU) induced by immunization with interphotoreceptor retinoid-binding protein (IRBP), a retinal self antigen, has been regarded to be a typical T helper type 1 (Th1)-mediated inflammatory disease. In this study, we examined the effect of a neutralizing monoclonal antibody (mAb) to interleukin-12 (IL-12), which has been known to play a critical role in the Th1 differentiation, on the development of EAU. While 9 of 13 control mice developed EAU by the immunization with IRBP, none of 12 mice developed EAU when given anti-IL-12 mAb 1 day before immunization. These mice did not develop EAU even after a rechallenge with IRBP on day 30, indicating that a protective mechanism had been established by the anti-IL-12 treatment. The proliferative response of splenocytes to IRBP in vitro was not significantly impaired, but the production of IL-2 and IFN-gamma was greatly reduced by the anti-IL-12 treatment. Moreover, production of IL-5 and expression of IL-4 mRNA were increased by the anti-IL-12 treatment. Consistently, IgG2a anti-IRBP serum antibodies were decreased and IgG1 were increased. Administration of a neutralizing anti-IL-4 mAb at the time of IRBP rechallenge reversed the protection established by the anti-IL-12 treatment at the primary immunization. These results indicate that the anti-IL-12 treatment at the IRBP priming not only prevented the development of pathogenic Th1 cells, but also induced suppressive Th2 cells that protect the animals from further challenge with the same antigen.

Animals↗