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Biomedical subjects

K Yasuda

Publications and source records attributed to K Yasuda.

At least 523 records · Page 29Linked to original sources
PubMed1996

Micturitional disturbance in syringomyelia.

Micturitional histories and urodynamic studies were performed in 14 patients with syringomyelia. Eleven patients were revealed to have urinary symptoms including difficulty of voiding in 8, urinary retention in 3, nocturnal and diurnal urinary frequency in 3, urinary incontinence in 2, and sense of urgency and enuresis in one. These urinary symptoms appeared after 5.3 years (ranging from 2 months to 13 years) from the occurrence of the neurological symptoms. Urodynamic studies revealed detrusor hyperreflexia in 7, detrusor areflexia in 4, detrusor-sphincter dyssynergia in 4 and uninhibited sphincter relaxation in 2 patients. Analysis of the motor unit potentials of the external sphincter revealed 5 of 6 patients had high amplitude or polyphasic neurogenic changes. Supranuclear as well as nuclear types of parasympathetic and somatic nerve dysfunctions seemed to be responsible for micturitional disturbance in our patients with syringomyelia. During the follow-up period of 2 to 63 months, urinary symptoms gradually improved in 4 of 6 patients after syringosubarachnoid shunts and in 3 of 4 after alpha-adrenoreceptor blocking agents.

Adult↗
PubMed1996

Growth hormone secretion in human acromegalic pituitary adenomas: cyclic adenosine monophosphate and protein kinase C responses.

We examined the effect of phorbol ester on growth hormone (GH)-releasing hormone (GRH)-induced GH secretion and cyclic adenosine monophosphate (cAMP) production in three pituitary adenomas and thyrotropin-releasing hormone (TRH)- and corticotropin-releasing hormone (CRH)-induced redistribution of protein kinase C (PKC) from cytosol to membrane in a pituitary adenoma resected from patients with acromegaly. GRH stimulated GH secretion in accordance with cAMP production in three cases, whereas 12-O-tetradecanoyl phorbol-13 acetate (TPA) stimulated GH secretion with cAMP production in one case. Simultaneous addition of GRH and TPA enhanced cAMP production in three pituitary adenomas. Moreover, addition of TPA with GRH resulted in additive secretion of GH in vitro. In one case, we were able to measure PKC activity and prove translocation of PKC stimulated by TRH and CRH in accordance with GH secretion in vitro and in vivo. These results suggest that TPA, an activator of PKC, has a stimulatory effect on GRH-induced cAMP production and that, finally, TRH- and CRH-induced PKC activation may cause greater secretion of GH by enhancement of cAMP production in human GH-hypersecreting adenoma cells.

Acromegaly↗
PubMed1996

Micturition disturbance in acute transverse myelitis.

In ten patients with acute transverse myelitis (ATM), seven patients had urinary retention, and the other three patients had difficulty in voiding within 1 month from the onset of the disease. Five of the patients with retention became able to urinate. After the mean follow-up period of 40 months, nine still had urinary symptoms including difficulty in voiding in five and urinary frequency, urgency and incontinence in four patients. Four patients had urinary disturbance as the sole sequel of ATM. Urodynamic studies performed on nine patients revealed that all of the three patients with the urgent incontinence had detrusor hyperreflexia, all of the four patients with retention had an areflexic cystometrogram as well as sphincter hyperreflexia, and three of five patients with voiding difficulty had detrusor-sphincter dyssynergia. An areflexic cystometrogram tended to change to a low compliance bladder, followed by detrusor hyperreflexia or a normal cystometrogram. Analysis of the motor unit potentials of the external sphincter revealed that two of the three patients had high amplitude or polyphasic neurogenic changes. Supranuclear as well as nuclear types of parasympathetic and somatic nerve dysfunctions seemed to be responsible for micturition disturbance in our patients with ATM.

Acute Disease↗
PubMed1996

Prolonged fecal excretion of hepatitis A virus in adult patients with hepatitis A as determined by polymerase chain reaction.

In hepatitis A virus (HAV) infection, fecal excretion of the virus has been reported to cease shortly after symptoms occur. Although there have been several reports on detection of HAV in feces using polymerase chain reaction (PCR), the duration of fecal HAV shedding in human adult hepatitis A has not been well described. In the present study, we applied the reverse-transcription (RT)-PCR system to the detection of fecal HAV RNA in 10 patients with sporadic hepatitis A. The viral genomic RNA was detected in the stools from five patients after the onset of clinical symptoms. All stool samples collected within 10 days of onset of illness were HAV-RNA-positive, and the duration of positivity lasted from a few days to as long as 3 months. In four patients, HAV RNA was detected in the stool even after the serum alanine transaminase (ALT) levels had peaked, and in one patient well after ALT levels fell to normal. These results show that fecal shedding of HAV can last for months after resolution of symptoms and such patients could be a source of further spreading of the virus in the community.

Adult↗
PubMed1996

Identification and immunohistochemical localization of macrophage migration inhibitory factor in human kidney.

Macrophage migration inhibitory factor (MIF) was the first lymphokine identified in activated T-lymphocytes. MIF can induce proinflammatory cytokines, such as interleukin-1 and tumor necrosis factor-alpha. In this study, we identified MIF expression in a tissue specimen of a normal portion of a nephrectomized human kidney by reverse transcription-polymerase chain reaction (RT-PCR) and Western blot analysis. Furthermore, immunohistochemical study using an anti-human MIF polyclonal antibody demonstrated that MIF was mostly present in the renal tubule epithelial cells and, to a lesser extent, in Bowman's capsular epithelial cells. We also carried out immunohistochemistry on cultured human renal proximal tubule epithelial cells, which showed that MIF was present in the cytoplasm of the epithelial cells. These results suggest the possibility that MIF takes part in the mechanism of inflammation and immunological events in the human kidney.

Blotting, Western↗
PubMed1996

Effect of estrogens on plasma platelet-activating factor acetylhydrolase and the timing of parturition in the rat.

In the present study we examined the effects of estrogens on plasma platelet-activating factor acetylhydrolase (PAF-AH) activity in pregnant rats in an attempt to further define the role of platelet-activating factor (PAF) in parturition. The plasma PAF-AH activity decreased starting on Day 13 of pregnancy and reached its lowest level by Day 19 (36.5 +/- 5.7 nmol.min-1.ml-1 plasma, mean +/- SD). The maternal plasma PAF-AH activity rapidly increased to 67.3 +/- 3.5 nmol.min-1.ml-1 plasma by Day 2 postpartum, to 88.8 +/- 14.4 by Day 7, and to 109.1 +/- 4.4 by Day 21, returning to nonpregnant levels by Day 35 in the dams that were allowed to nurse through Day 21. The PAF-AH activity did not increase in dams from which the pups were removed 2 days after delivery. When 17 alpha-ethynylestradiol (0.25 mg/kg) was administered s.c. to pregnant rats for 3 days starting at Day 17 of pregnancy, the plasma PAF-AH activity in the animals decreased by 80% on Day 19, and the rats delivered prematurely on Day 21. When a similar dose of 17 alpha-ethynylestradiol was injected into the pregnant rats for 3 days starting on Day 15, the enzyme activity again decreased by approximately 80% on Day 17 and Day 19 of pregnancy; however, it returned to a value similar to that seen in the controls by Day 21, and the time at which the treated rats delivered was similar to that for the control animals. These observations provide further support for a role of PAF and PAF-AH and their possible regulation by estrogens in the initiation and maintenance of parturition.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1996

Case report: diabetic microangiopathic hemolytic anemia and thrombocytopenia with antiphospholipid syndrome.

A 38 year-old man with a 12-year history of noninsulin-dependent diabetes mellitus with rapidly progressive diabetic complications presented with microangiopathic hemolytic anemia and thrombocytopenia. He had no disorders that could induce microangiopathic hemolytic anemia other than diabetic microangiopathy. In addition, there was a significant negative correlation between serum lactate dehydrogenase levels and peripheral platelet counts, which suggested that the hemolysis and thrombocytopenia occurred through the same mechanism. Activated partial thromboplastin time was slightly prolonged, and lupus anticoagulant and antiphospholipid immunoglobulin G antibodies were positive. Both the hemolysis and the thrombocytopenia spontaneously improved after the initiation of hemodialysis. This is a unique case of diabetic microangiopathic hemolytic anemia and thrombocytopenia in which antiphospholipid syndrome also may be involved.

Adult↗
PubMed1996

Disseminated superficial porokeratosis with amyloid deposition.

Two patients with disseminated superficial porokeratosis (DSP) with amyloid deposition are reported. The skin lesions were distributed over both sun-exposed areas and sun-protected areas. No exacerbation by sun exposure was noted. Abundant amyloid substances were deposited at the papillary dermis, not only beneath the cornoid lamellae but also within the annular margin. The skin lesions and amyloid deposition regressed with topical application of dimethyl sulfoxide in one patient, suggesting that DSP is one of the clinical phenotypes of primary localized cutaneous amyloidosis. Another possibility is that amyloid substances are produced by poorly differentiated keratinocytes in DSP.

Administration, Topical↗
PubMed1996

Palmar erythema ab igne without detectable type IV collagen at the basement membrane zone.

A 42-year-old baker had hyperkeratotic lesions on reticular erythema of his palms and volar digits. Attachment between the epidermis and the dermis was loose at the hyperkeratotic sites, but no blisters had formed. After he stopped work for 2 months, the skin lesions disappeared, leaving a slight scar. Immunofluorescence studies showed a normal distribution of type VII collagen and laminin, but there was almost no fluorescence for type IV collagen in the basement membrane zone. Disappearance of cytoplasmic organelles and aggregated tonofibrils was evident under electron microscopy in the basal cells which appeared shrunken under light microscopy. The structures of lamina lucida, basal lamina and anchoring fibrils were disarranged. The loose dermo-epidermal attachment is probably due in part to this disorganized basement membrane structure lacking type IV collagen, which may have been digested by heat-activated matrix metalloproteinases. In addition, his work-related chronic heat exposure might have caused hyperproliferation of keratinocytes.

Adult↗
PubMed1996

Distribution and anti-inflammatory effect of mesalazine on carrageenan-induced colitis in the rabbit.

1. A controlled-release preparation of mesalazine microgranules (PentasaR; Ferring AS, Vanlose, Denmark) releases the active ingredient over a wide area from the small intestine to the rectum and is consequently expected to bring about therapeutic benefits to patients with ulcerative colitis and Crohn's disease. 2. Mesalazine microgranules (50 or 150 mg/kg per day) were administered orally to each rabbit with carrageenan-induced colitis for six weeks. Its inhibitory effect on colonic mucosal damage was assessed in terms of the microscopic damage scores, leukotriene B4 concentrations and concentrations of mesalazine derivatives. 3. At the end of the experiment, the mesalazine 150 mg group had gained a significantly greater bodyweight than the control group. Microscopic damage was significantly lower in the 150 mg group than in the untreated control group. Tissue concentrations of 5-aminosalicylic acid and acetyl-5-amino-salicylic acid in the small and large intestine were higher in the 150 mg group than in the 50 mg group. Mucosal leukotriene B4 levels tended to be lower in rabbits receiving the larger dose of mesalazine. 4. The present study indicates that slow release 5-amino-salicylic acid at the larger dose reaches the large bowel in sufficiently high concentrations following oral administration and significantly reduces carrageenan-induced colitis in the rabbit.

Aminosalicylic Acids↗
PubMed1996

Effects of restressing on the mechanical properties of stress-shielded patellar tendons in rabbits.

We studied the effects of restressing on the mechanical properties and morphology of stress-shielded rabbit patellar tendons. After completely unloading the patellar tendon for 1 to 3 weeks, tension was again applied to the tendon for subsequent 3 to 12 weeks. Although the stress shielding markedly decreased the tangent modulus and tensile strength of the tendon, restressing significantly increased them. However, the mechanical properties of the tendon were not completely recovered even after a prolonged period of restressing. The microstructure of the tendon was also restored by restressing, although the recovery was incomplete. These results indicate that the mechanical properties and morphology of tendinous tissue change in response to mechanical demands.

Animals↗
PubMed1996

Contact analysis of ultrahigh molecular weight polyethylene articular plate in artificial knee joint during gait movement.

To understand the wear mechanism of the ultrahigh molecular weight polyethylene (UHMWPE) articular plate used in artificial knee joints, the cyclic contact behavior of the plate during gait movement was analyzed using the constitutive equation for cyclic plasticity. In this study, two-dimensional plane strain model was employed and the contact behavior of femoral and tibial components was simulated by translating the contact stress distribution which was calculated from elasto-plastic indentation analysis of two components. For analytical model, the anatomical type artificial knee joint was employed and the effect of the shape of contact surface on the wear behavior of the plate was investigated. As a result, it was clarified that the wear of the plate should occur both from the surface and the subsurface of the plate and the wear behavior of the plate should be closely related with the shape of contact surface. Then the optimum shape of contact surface could be designed using this method.

Biomechanical Phenomena↗
PubMed1996

Mutation of cytochrome P-45017 alpha gene (CYP17) in a Japanese patient previously reported as having glucocorticoid-responsive hyperaldosteronism: with a review of Japanese patients with mutations of CYP17.

A 17-yr-old female Japanese patient, who was reported in 1968 as having glucocorticoid-responsive hyperaldosteronism but was presumed to have a defect of 17 alpha-hydroxylation mainly in the adrenal glands as the etiology of her illness, was followed. The relationship between clinical manifestations and molecular abnormalities in cytochrome P-45017 alpha gene (CYP17) was also reviewed based on the literature on Japanese patients with 17 alpha-hydroxylase deficiency. She has been treated with dexamethasone, resulting in normal blood pressure and normokalemia for 28 yr. She had almost normal gonadal function with regular menstruation on her first admission. Because of sustained genital bleeding, however, she underwent total hysterectomy with an ovarian biopsy at the age of 42 yr. No follicles or corpus luteum were detected in the ovarian specimen. At the age of 45 yr, the basal levels of sex steroids were decreased, while those of gonadotropins were increased. A genetic study on CYP17 revealed a homozygous deletion of phenylalanine (Phe) codon (TTC) at either amino acid position 53 or 54 in exon 1. A review of the literature revealed 4 patients with this type of CYP17 mutation, including the present patient, out of a total of 11 young adult Japanese patients. The clinical manifestations caused by congenitally deficient gonadal function were not marked in any of these 4 patients, but were marked in 5 of the 7 patients with different mutations of CYP17. The remaining 2 female patients had irregular menstruation. The pretreatment urine/plasma values of aldosterone were variable, normal to high, in individual patients, regardless of the structural abnormalities of CYP17. The following conclusions were suggested: 1) this type of CYP17 mutation is associated with well preserved gonadal function in young adult patients, but it likely causes early reduction of gonadal function with increasing age in these patients; 2) the prevalence of this type of CYP17 mutation is quite high in Japanese patients; and 3) the pretreatment hyperaldosteronism observed in the present patient seems not to be related to the mutation of CYP17.

Adolescent↗
PubMed1996

Aerodynamic characteristics of the wings and body of a dragonfly

The aerodynamic characteristics of the wings and body of a dragonfly and of artificial wing models were studied by conducting two types of wind-tunnel tests and a number of free-flight tests of gliders made using dragonfly wings. The results were consistent between these different tests. The effects of camber, thickness, sharpness of the leading edge and surface roughness on the aerodynamic characteristics of the wings were characterized in the flow field with Reynolds numbers (Re) as low as 103 to 104.

Journal Article↗
PubMed1996

Studies on agents with vasodilator and beta-blocking activities. IV.

A series of novel pyridazinone derivatives (II) having a phenoxypropanolamine moiety was synthesized. Their hypotensive and beta-blocking activities were evaluated after intravenous administration of the compounds to anesthetized rats. Among them, the 5-chloro-2-cyanophenoxy derivative (29) showed the promising dual activities and was selected for further studies.

Adrenergic beta-Antagonists↗