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Biomedical subjects

H Yasuda

Publications and source records attributed to H Yasuda.

At least 181 records · Page 10Linked to original sources
PubMed1999

An immunohistochemical study of the apocrine type of cutaneous mixed tumors with special reference to their follicular and sebaceous differentiation.

An immunohistochemical analysis of 8 cases of the apocrine type of cutaneous mixed tumor is reported. Histologically, 7 cases of the tumor were suggested to have follicular and/or sebaceous differentiation. Carcinoembryonic antigen (CEA), epithelial membrane antigen and gross cystic disease fluid protein-15 were present in the inner surface and/or in the luminal cell bodies of the tubular structures. CEA and non-specific cross-reacting antigen were also detected in the keratinous cysts. Positive reactions for S-100 protein and vimentin were observed in the solid nests, the outer layer of the tubular structures and some stromal cells. However, smooth muscle actin was only focally expressed in the outer cells of the tubular nests in one case. Involucrin was positive in the inner layers of the keratinous cysts. Various staining patterns were observed in the keratin immunohistochemistry. The solid nests showed heterogeneous expressions of CK1/5/10/14, CK7, CK10/11, CK14, CK8/18 and CK19. The inner cells of the tubular structures were constantly positive for CK7, CK8/18 and CK19, and heterogeneously for CK1/5/10/14, CK10/11 and CK14. The outer cells were heterogeneously positive for CK1/5/10/14 and CK14. The keratinous cysts showed positive reactions for CK1/5/10/14 throughout the whole cell layers, and for CK14 in the basal layer. The inner layers in some keratinous cysts expressed CK6, CK10/11 and CK17, but only CK10 in others. CK13 was positively stained in the transitional portion between the matricial structure and the column of shadow cells in the cyst wall in only one case. When compared with the immunohistochemistry of the normal skin, the apocrine type of cutaneous mixed tumor can show various immunophenotypical patterns similar to those of entire structures of hair follicles, sebaceous glands and all components of apocrine glands, that is to say, the folliculosebaceous-apocrine unit.

Adenoma, Pleomorphic↗
PubMed1999

Endothelium-specific activation of NAD(P)H oxidase in aortas of exogenously hyperinsulinemic rats.

To examine the effects of chronic hyperinsulinemia on vascular tissues, we examined the production of superoxide anion (O(-2)) in the aortic tissues of control and exogenously hyperinsulinemic rats performed by the implantation of an insulin pellet for 4 wk. O(-2) production by aortic segments from hyperinsulinemic rats was 2. 4-fold (lucigenin chemiluminescence method) and 1.7-fold (cytochrome c method) of that of control rats without any differences in O(-2) degrading activities in aortic tissues, respectively (P < 0.025). The increment was completely abolished in the presence of either 100 micromol/l apocynin (an inhibitor of NADPH oxidase) or 10 micromol/l diphenyleneiodonium (an inhibitor of flavin-containing enzyme) and was exclusively endothelium dependent. Consistently, NAD(P)H oxidase activities in endothelial homogenate in hyperinsulinemic rats were dose dependently stimulated above the values of control rats, although these activities in nonendothelial homogenate were not significantly stimulated by insulin. Furthermore, an insulin effect was also demonstrated 1 h after exposing aortic tissues to insulin. These results indicate that O(-2) production specifically increases in endothelium of aortic tissues in chronic hyperinsulinemic rats through the activation of NAD(P)H oxidase.

Animals↗
PubMed1999

Assessment of exocrine pancreatic dysfunction in chronic pancreatitis.

The clinical diagnosis of chronic pancreatitis is usually based on imaging studies, pancreatic function tests, and the presence of characteristic clinical features. In Japan, diagnostic criteria for chronic pancreatitis were established in 1995. The secretin test (a duodenal intubation test) and the combination of noninvasive tests, N-benzoyl-L-tyrosyl-p-aminobenzoic acid (BT-PABA) and fecal chymotrypsin (FCT), have been recommended for evaluating exocrine pancreatic function in patients with chronic pancreatitis. In the present study, the diagnostic value of these two noninvasive tests was compared to the secretin test. Although noninvasive tests are less sensitive and specific for determining exocrine pancreatic dysfunction than the secretin test, greater reliability for diagnosing chronic pancreatitis can be obtained by performing the BT-PABA and FCT simultaneously. Assessment of exocrine pancreatic function is important not only to diagnose chronic pancreatitis but also to decide a treatment method with pancreatic enzyme preparation.

4-Aminobenzoic Acid↗
PubMed1999

Synthesis and enzymatic degradation of optically active depsipeptide copolymers.

This paper describes the synthesis and biodegradation of copolymers of cyclic depsipeptide with epsilon-caprolactone (CL) or lactide (LA). Optically active cyclic depsipeptides, 3,6-dimethyl-2,5-morpholinediones (DMOs), were prepared by the reaction of an amino acid (D-, L-, or DL-alanine) with a hydroxy acid derivative (DL-2-bromopropionyl bromide). These isomers are abbreviated as D-DMO, L-DMO and DL-DMO respectively, according to the names of alanine isomers. Then, we have prepared the copolymers of DMO isomers with CL using tin(II) octylate as a catalyst. The NMR spectra and thermal properties of DMO/CL copolymers revealed that these copolymers exist randomly. The enzymatic degradation of the copolymers has been examined using Rhizopus delemar lipase, cholesterol esterase (from Pseudomonas sp.), and Proteinase K (from Tritirachium album). Cholesterol esterase and Proteinase K show high degradability, while the lipase shows little degradation. Among the enzymes used, only Proteinase K could recognize the isomerism of DMO, resulting in the following order of degradability: copoly(L-DMO/CL) > copoly(DL-DMO/CL) > copoly(D-DMO/CL), i.e. this enzyme has the highest substrate specificity for naturally occurring L-alanine. Further, we have prepared the random copolymers of L-DMO with lactide (L-LA or DL-LA), and evaluated the enzymatic degradation of the copolymers by Proteinase K. The introduction of a small amount (up to c. 10 mol%) of L-DMO unit into LA homopolymers brought about greater degradability compared with LA homopolymers. In particular, L-DMO/L-LA copolymers with high degradability have been obtained without significant decrease in the mechanical and thermal properties of L-LA homopolymer.

Endopeptidase K↗
PubMed1999

Pseudogout attack associated with chronic thyroiditis and Sjögren's syndrome.

A 66-year-old woman, diagnosed with chronic thyroiditis at age 63, presented with anorexia and fatigue. Therapy for the chronic thyroiditis consisted of levothyroxine sodium (100 microg/day). Her symptoms were attributed to the insufficient supply of levothyroxine sodium. Following a dosage increase to 150 microg/day, she suffered from an acute attack of pseudogout. Clinical features were complicated by Sjögren's syndrome, which appeared after treatment onset. Pseudogout was effectively treated by colchicine after administration of diclofenac sodium failed to alleviate the symptoms. Pseudogout is a recognized complication of thyroid replacement therapy, but association with Sjögren's syndrome has not been previously reported.

Aged↗
PubMed1999

The 3'-untranslated region polymorphism of the gene for skeletal muscle-specific glycogen-targeting subunit of protein phosphatase 1 in the type 2 diabetic Japanese population.

A newly identified 3'-untranslated region (UTR) polymorphism of the gene for skeletal muscle-specific glycogen-targeting subunit of protein phosphatase 1 (PPP1R3) was associated with insulin resistance and type 2 diabetes in Pima Indians (Xia J, Scherers W, Cohen PTW, Majer M, Xi T, Norman RA, Knowler WC, Bogardus C, Prochazka M: A common variant in PP1R3 associated with insulin resistance and type 2 diabetes. Diabetes 47:1519-1524, 1998). Thus, we investigated the frequency of polymorphism of the adenine- and thymine-rich element (ARE-1 and its variant ARE-2) in 426 Japanese type 2 diabetic and 380 nondiabetic subjects using a polymerase chain reaction (PCR)-restriction enzyme fragment length polymorphism (RFLP) method. The allele frequency of the ARE-2 variant in diabetic subjects was higher than that in nondiabetic subjects (0.34 vs. 0.29; P < 0.05), even though its frequency in Japanese subjects was lower (P < 0.001) than the reported value in Pima Indians (0.56). An aspartate polymorphism at codon 905 was 100% coupled to the ARE-2 allele, and its allele frequency was higher also in diabetic subjects. Although a serine substitution at codon 883 was partially linked with the ARE-2 allele, there was no difference between diabetic and nondiabetic subjects. These results indicate that the frequency of polymorphism of the PPP1R3 gene (ARE-2 and Asp905) is different between two ethnic groups and is increased in Japanese people with type 2 diabetes, suggesting that these variants may be a possible marker for searching for diabetogenic genes.

3' Untranslated Regions↗
PubMed1999

[Levofloxacin-induced neurological adverse effects such as convulsion, involuntary movement (tremor, myoclonus and chorea like), visual hallucination in two elderly patients].

Levofloxacin-induced-neurological adverse events such as convulsion, involuntary movement (tremor, myoclonus and chorea-like) and visual hallucination in two elderly patients are reported. A 67-year-old man with minor alcoholism and a past-history of gastrectomy and cholecystectomy was given 300 mg/day of oral levofloxacin and fulfenamic acid for an upper respiratory infection. On the 4th day, he reported gradual exacerbation of hand tremor which resembled chorea-like involuntary movement and gait disturbance. He also experienced visual hallucinations. On the 7th day, he suffered generalized convulsions and was admitted. Serum concentration of levofloxacin at this time (3 hours after last administration of a 100 mg tablet of levofloxacin) was 3.6 micrograms/ml. Cessation of the agents promoted complete recovery of these neurological adverse effects within a week. Another 85-year-old man with chronic bronchitis and slight renal impairment received long term administration of 200 mg/day of levofloxacin. On the 68th day of administration, gradual exacerbation of gait disturbance, dysarthria and chorea-like involuntary movement occurred. On the day of admission, 76 days after the start of administration, the serum level of levofloxacin was 2.55 micrograms/ml and that of spinal fluid was 1.12 micrograms/ml (3 hours after the last administration of a 100 mg tablet of levofloxacin). Cessation of the agents promoted complete recovery of these neurological adverse effects within the next two weeks. Both patients had no apparent neurological disorders except age-related brain atrophy. Age-related renal and brain impairment might have contributed to the neurological adverse effects of levofloxacin.

Aged↗
PubMed1999

[A case of cerebellar hematoma due to venous angioma presenting trigeminal dysfunction].

With regard to the natural history of venous angioma, the risk of hemorrhage is reported to be relatively higher if the lesion exists in the posterior fossa. However a recent report of 100 cases of venous angioma concluded that the risk of hemorrhage was low, being only 0.22%/year. Although the true rate of hemorrhage is uncertain, we have encountered case of cerebellar hematoma due to venous angioma in the posterior fossa where the patient presented with trigeminal dysfunction and cerebellar ataxia, without any history of hypertension. We considered that venous angioma in the posterior fossa might cause cerebellar hemorrhage. After removal of the hematoma, the patient's symptoms were resolved. In the posterior fossa, a relatively higher volume of venous blood would cause venous congestion to occur more easily, leading to damage of the fragile wall of the angioma.

Cerebellar Ataxia↗
PubMed1999

Endoneurial microvasculature of chronically transected sciatic nerves in diabetic rats.

To characterize the morphology of the endoneurial microvasculature of degenerating nerves under hyperglycemia, the morphology of endoneurial microvessels in transected sciatic nerves was examined in normal and streptozotocin-induced diabetic rats. Three months after transection, the fascicular area and median vascular luminal area at the proximal level of the distal stump were significantly larger in diabetic than in control animals, whereas the number of vessels per fascicle was the same in the two groups. Arterioles in various stages of development were found in the centrifascicular region in some transected nerves. Serial sections revealed that these vessels originated from transperineural arterioles. The frequency and magnitude of vascular wall thickening were both greater in diabetic rats. These results suggest that the endoneurial microvasculature responds abnormally to nerve injury under hyperglycemia.

Animals↗
PubMed1999

[Diabetic neuropathy: clinical and experimental progress in its pathogenesis and treatment].

Diabetic symmetrical polyneuropathy have been known to arise from metabolic alteration such as accelerated polyol pathway and/or from neurovascular deficit. Recently, two other hypotheses were confirmed. Decreased neurotrophic supports were reported in diabetic neuropathy. Subcutaneous injection of recombinant human nerve growth factor ameliorated sensory symptoms and cooling detection threshold. The most common adverse effect was injection site hyperalagesia. Brain-derived neurotrophic factor, neurotrophin-3 and insulin-like growth factors are under clinical trials. The excessive oxidative stresses are also associated with diabetic neuropathy. Increased production and decreased scavenge system of free radicals enhance their cytotoxic effects. Alpha-lipoic acid, gliclazide and troglitazone have been reported to be effective for diabetic neuropathy.

Animals↗
PubMed1999

[New trend in pathogenesis of diabetic neuropathy].

The pathogenesis of diabetic neuropathy remains unclear, although several factors have been implicated in its pathogenesis. We have examined possible roles of decreased production of nitric oxide, ion channel dysfunction and decreased capacity of nerve regeneration. STZ-induced diabetic rats showed decreases in nociceptive threshold and NADPH-diaphorase positive neurons, nNOS level and cGMP content of DRG at 12 weeks after induction of diabetes. The rats injected by L-NAME, potent nNOS inhibitor, showed decreased nociceptive threshold, although D-NAME, inactive in nNOS inhibition, did not. These results suggest that decreased NO production might be involved in hyperalgesia in diabetic rats. Both hyperglycemia and decreased Na/K-ATPase activity are thought to be characteristic features of diabetic neuropathy. To investigate the presence of ion channel abnormality in diabetic nerves, a Vaseline-gap voltage clamp technique was applied for a single myelinated fibers under 30 mM high glucose plus 0.1 mM ouabain. Since K current was increased, a Ca activated K channel blocker was applied and this increase was shown to be suppressed. Furthermore, Ca channel blockers all suppressed increased K currents, suggesting that the condition induced an increase of Ca influx, thereby increasing Ca activated K currents through K channels. The data are important in that diabetic condition may induce both Ca influx, leading to nerve degeneration, and increased K current, resulting in decreased nerve conduction. Nerve regeneration has been known to be disturbed in diabetic condition. We have shown a decrease in nerve elongation rate in diabetic rats after crush of sciatic nerve, although this decrease was not ameliorated by ARI. Furthermore, Wallerian degeneration was shown to be delayed in diabetic nerves, leading to delayed nerve regeneration. Hyperphosphorylation of both medium and high molecular weight neurofilaments that might be induced by protein kinases including CDK 5 may be involved in the mechanism.

Animals↗
PubMed1999

[Ruptured persistent primitive hypoglossal artery aneurysm: case report].

Persistent primitive hypoglossal artery is less common than persistent primitive trigeminal artery. About one hundred examples of such hypoglossal arteries have been demonstrated by angiography. The origin of persistent primitive hypoglossal artery is the cervical segment of the internal carotid artery, usually at the level of the first to second cervical vertebrae. The artery then enters, with varying degrees of tortuosity, the anterior condyloid (hypoglossal) canal and joints the basilar artery immediately above its lower end. When enlargement of this canal is identified, the presence of a persistent primitive hypoglossal artery should be strongly suspected. The homolateral vertebral artery is frequently hypoplasia. A 66-year-old man was brought to our hospital due to faintness. CT showed thick subarachnoid hemorrhage. Angiography showed that a persistent primitive hypoglossal artery aneurysm was present, but the posterior communicating artery was absent. Right vertebral angiography showed extravasation due to re-rupture of the aneurysm. An operation was performed at day 0 using the left transcondylar approach despite deterioration of SAH grading. Intraoperative re-rupturing occurred and the lower cranial nerves clustered around the aneurysm, so the aneurysm was partially clipped on the dome. The second angiography was carried out at day 10, and there was no vasospasm. Palsy of the lower cranial nerves appeared transiently. A ventricle-peritoneum shunt was required due to normal pressure hydrocephalus, but the patient was discharged with no neurological deficits.

Aged↗
PubMed1999

Organ/Tissue absorbed doses measured with a human phantom torso in the 9th Shuttle-Mir Mission (STS-91).

Organ/Tissue absorbed doses were measured with a life-size human phantom torso in the 9th Shuttle/Mir Mission (STS-91) from June 2 to 12, 1998. This is the first attempt to measure directly organ/tissue doses over a whole human body in space. The absorbed dose was measured by combination of two integrating detectors: thermo- luminescent dosemeter of Mg2SiO4: Tb (TDMS) and plastic nuclear track detector (PNTD). Both detectors were calibrated on ground using high-energy charged-particle beams. The detectors were packed in 59 cases of tissue-equivalent resin; and put into the positions of radiologically important organs and tissues in the phantom. Efficiency reductions of TDMS for high-LET particles were corrected based on the LET-differential particle fluence of space radiation measured with PNTDs. The accumulated absorbed doses during this 9.8-days mission at low-earth orbit (400 km x 51.6 degrees) ranged from 1.6 mGy at colon to 2.6 mGy at bone surface (shoulder) with a variation factor of 1.6. The absorbed doses at some internal organs were higher than the skin dose. This fact is important from the viewpoint of radiological protection for astronauts.

Cosmic Radiation↗
PubMed1998

RANK is the essential signaling receptor for osteoclast differentiation factor in osteoclastogenesis.

Osteoclast differentiation factor (ODF) is a ligand for osteoclastogenesis-inhibitory factor/osteoprotegerin (OCIF/OPG), and mediates an essential signal for osteoclastogenesis. Soluble-form ODF binds directly to osteoclast progenitors, suggesting the presence of a membrane-bound receptor for ODF (ODFR) on the cells. To understand the ODF-mediated signal transduction mechanism in osteoclastogenesis, we molecularly cloned ODFR from a mouse macrophage-like osteoclast progenitor cell line, C7. Nucleotide sequence analysis revealed that ODFR is identical to RANK, a recently identified member of the tumor necrosis factor receptor (TNFR) family, which is involved in the regulation of dendritic cell function. A polyclonal antibody against the extracellular domain of RANK induced osteoclastogenesis in the presence of macrophage colony-stimulating factor (M-CSF). In contrast, both a genetically engineered soluble RANK and Fab fragment of the antibody blocked the binding of ODF to RANK and ODF-mediated osteoclastogenesis. These results indicate that RANK is the signaling receptor essential for ODF-mediated osteoclastogenesis.

Animals↗
PubMed1998

Differential activity of the G protein beta5 gamma2 subunit at receptors and effectors.

The G protein beta5 subunit differs substantially in amino acid sequence from the other known beta subunits suggesting that beta gamma dimers containing this protein may play specialized roles in cell signaling. To examine the functional properties of the beta5 subunit, recombinant beta5 gamma2 dimers were purified from baculovirus-infected Sf9 insect cells using a strategy based on two affinity tags (hexahistidine and FLAG) engineered into the N terminus of the gamma2 subunit (gamma2HF). The function of the pure beta5 gamma2HF dimers was examined in three assays: activation of pure phospholipase C-beta in lipid vesicles; activation of recombinant, type II adenylyl cyclase expressed in Sf9 cell membranes; and coupling of alpha subunits to the endothelin B (ETB) and M1 muscarinic receptors. In each case, the efficacy of the beta5 gamma2HF dimer was compared with that of the beta1 gamma2HF dimer, which has demonstrated activity in these assays. The beta5 gamma2HF dimer activated phospholipase C-beta with a potency and efficacy similar to that of beta1 gamma2 or beta1 gamma2HF; however, it was markedly less effective than the beta1 gamma2HF or beta1 gamma2 dimer in its ability to activate type II adenylyl cyclase (EC50 of approximately 700 nM versus 25 nM). Both the beta5 gamma2HF and the beta1 gamma2HF dimers supported coupling of M1 muscarinic receptors to the Gq alpha subunit. The ETB receptor coupled effectively to both the Gi and Gq alpha subunits in the presence of the beta1 gamma2HF dimer. In contrast, the beta5 gamma2HF dimer only supported coupling of the Gq alpha subunits to the ETB receptor and did not support coupling of the Gi alpha subunit. These results suggest that the beta5 gamma2HF dimer binds selectively to Gq alpha subunits and does not activate the same set of effectors as dimers containing the beta1 subunit. Overall, the data support a specialized role for the beta5 subunit in cell signaling.

Adenylyl Cyclases↗