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Biomedical subjects

N Yamada

Publications and source records attributed to N Yamada.

At least 217 records · Page 12Linked to original sources
PubMed1999

Ossifying fibromyxoid tumor of soft parts: clinicopathologic, immunohistochemical and ultrastructural study of four cases.

Four cases of uncommon soft tissue tumors were investigated histopathologically. All of them consisted of fibrous and myxoid components, and mature bone showed shell-like characteristics. Histological features revealed these tumors were well circumscribed by a thick collagenous fibrous capsule and composed of uniform-sized fusiform cells with eosinophilic cytoplasm and a round or oval nucleus in the myxoid matrix. An incomplete shell of mature bone with lamellar structure was also observed at the periphery. Immunohistochemical and ultrastructural studies were performed. The major component of the proliferating cells in the tumors had positive staining for vimentin, S-100 protein, neuron-specific enolase and synaptophysin. The myxoid matrix was stained by alcian blue and was digested completely by pretreatment with hyaluronidase. Electron microscopy showed the cytoplasm contained dense-core granules measuring 100-200 nm and abundant filaments of an intermediate size. It is suggested that these uncommon tumors might be diagnosed as the 'ossifying fibromyxoid tumor of soft parts' previously described by Enzinger et al., which were derived from peripheral nerve sheath tumors such as neurofibroma and myxoid neurofibroma.

Adult↗
PubMed1999

Clinical evaluation of an allogeneic cultured dermal substitute composed of fibroblasts within a spongy collagen matrix.

We have developed an allogeneic cultured dermal substitute (CDS) that was prepared by plating fibroblasts on to a spongy collagen matrix and culturing them for 7 to 10 days. The matrix was freeze-dried from a 1% aqueous solution of bovine-hide atelocollagen. This study was designed to evaluate the efficacy of promoting epithelialisation clinically on 26 donor-site wounds for split-thickness skin grafts. One half of a wound was covered with an allogeneic CDS and the other half side was covered with a commercially-available freeze-dried porcine dermis (FPD). Both macroscopically and histologically the epithelialisation on the area of the donor site that was covered with allogeneic CDS was more rapid than that covered with FPD. In a representative donor-site wound covered with allogeneic CDS, there was a stratified structure of epithelial cells on the underlying connective tissue on day 5, and the epithelium had matured by day 12. When covered with FPD a stratified structure of epithelial cells was noted on day 8, and the epithelium had matured by day 15. We conclude that allogeneic CDS provides a good environment for epithelialisation.

Adult↗
PubMed1999

MTHFR gene variant is not associated with diabetic nephropathy in Japanese.

Genetic predisposition has been implicated in diabetic nephropathy. The C677T variant of the MTHFR gene has been suggested to play a role in the development of not only vascular diseases but also diabetic microangiopathies. By using polymerase chain reaction-restriction length polymorphism (PCR-RFLP) method using Hinf I, we investigated whether this variant is associated with diabetic nephropathy in Japanese. By analysing 274 unrelated Japanese patients with type II DM with or without nephropathy, there was no significant difference in the genotype distribution of this variant. The distribution of the three genotypes were not different among patients with micro- or macroalbuminuria and those without nephropathy. Although previous reports suggest a role of this variant with diabetic microangiopathies, our observations suggest that this variant is does not play an important role in the pathogenesis of diabetic nephropathy in Japanese.

Adult↗
PubMed1999

cDNA cloning of sesquiterpene cyclase and squalene synthase, and expression of the genes in potato tuber infected with Phytophthora infestans.

Sesquiterpene cyclase and squalene synthase are key branch point enzymes in isoprenoid pathway for the synthesis of sesquiterpenoid phytoalexins and sterols/steroid glycoalkaloids, respectively. cDNA clones encoding these enzymes were isolated from potato. A phylogenetic tree showed that the sesquiterpene cyclase is vetispiradiene synthase. Infection of Phytophthora infestans with potato tubers caused transient increases in the transcript level of vetispiradiene synthase in a compatible and an incompatible interactions. On the other hand, wound-induced expression of the squalene synthase was suppressed in favor of the expression of vetispiradiene synthase regardless of inoculated races.

Amino Acid Sequence↗
PubMed1999

Hemostatic markers in Japanese patients undergoing anticoagulant therapy under thrombo-test monitoring.

The objective of this study was to evaluate several molecular markers of hemostasis in 84 patients with hypercoagulable state, treated with warfarin under thrombo-test (TT) monitoring; TT was expressed as percent of control (TT%). In all patients, the average values of international normalized ratio (INR) of prothrombin time (PT;PT-INR) was 1.68+/-0.49; this increase in PT-INR was not, however, significant in patients under TT% monitoring. There were no thrombotic or severe bleeding complications in these patients during a period of 2 years. Plasma levels of thrombin-antithrombin complex (TAT), plasmin-plasmin inhibitor complex (PPIC), D-dimer, and soluble fibrin monomer (sFM) were slightly increased, suggesting that anticoagulant therapy was not completely effective in our Japanese patients based on the values of TT%. Activated partial thromboplastin time, PT-INR, TT% and protein C activity were significantly correlated with the dose of warfarin; fibrinogen, activated thromboplastin, TAT, PPIC, D-dimer, sFM, protein S and thrombomodulin were not significantly correlated with the dose of warfarin. The PT-INR was negatively correlated with TT%, protein C and protein S, and the correlation between PT-INR and TT-INR was better than that between PT-INR and TT%. The range of TT% was not correlated with the plasma levels of TAT, PPIC, D-dimer or sFM, but the range of PT-INR was correlated with the plasma level of TAT, D-dimer and sFM. The percentage of TAT, D-dimer and sFM within normal range was significantly low in patients with high PT-INR. These finding showed that PT-INR is better than TT% for monitoring the anticoagulant therapy with warfarin, and that TT should be expressed as INR. The values of PT-INR should be more than 1.7 during the anticoagulant therapy with warfarin in Japanese patients with high risk of thrombosis.

Adult↗
PubMed1999

Autonomic function in hypertensive patients with neurovascular compression of the ventrolateral medulla oblongata.

OBJECTIVE: To study whether abnormalities of autonomic function exist in patients with essential hypertension and neurovascular compression (NVC) of the medulla oblongata. SUBJECTS AND METHODS: We studied 25 untreated patients with essential hypertension (13 men and 12 women, 27-74 years old). High-resolution magnetic resonance imaging and magnetic resonance angiography were used to detect NVC. Twenty-four-hour ambulatory monitoring of blood pressure and electrocardiogram were performed, and the power spectrum of heart rate variability was analyzed. On a separate day, various autonomic activity tests, including mental stress, hand grip, cold pressor, and Valsalva maneuver were performed. Baroreflex sensitivity was calculated from changes of blood pressure and R-R interval during phenylephrine infusion. A clonidine suppression test was also performed, with measurement of plasma catecholamine levels. RESULTS: Fourteen of 25 patients (56%) had NVC (C group), and 11 patients did not have NVC (NC group). There were no significant differences in age, sex, family history, or duration of hypertension between the C and NC groups. Average 24-h systolic blood pressure was similar between the two groups, although 24-h diastolic blood pressure was higher in the C group than the NC group. Daytime, night-time, and 24-h heart rate was significantly higher in the C group than in the NC group. Night-time low frequency/high frequency ratio was slightly higher in the C group. Plasma norepinephrine levels were significantly higher (467 +/- 217 versus 299 +/- 122 pg/ml), and baroflex sensitivity was slightly lower in the C group than in the NC group. Responses of blood pressure and heart rate to mental stress, cold pressor, hand grip, Valsalva maneuver, phenylephrine infusion, and clonidine tests were not significantly different between the two groups. CONCLUSIONS: NVC of the medulla oblongata was frequently found in patients with essential hypertension. Patients with NVC appeared to have enhanced sympathetic nervous activity compared with those without the compression.

Adult↗
PubMed1999

Histiocytic necrotizing lymphadenitis (Kikuchi's disease): the necrotic appearance of the lymph node cells is caused by apoptosis.

We report a case of histiocytic necrotizing lymphadenitis in a 28-year-old woman. The biopsy specimen of the enlarged lymph node showed lymphocytes, histiocytes, and a large amount of nuclear debris as well as marked eosinophilic deposits. We found DNA fragments by means of the modified TUNEL method, especially in the transitional area between intact cells and the foci of eosinophilic deposits and the cells positive for anti-Fas antibody in the biopsied lymph node. Therefore, the necrotic appearance of the lymph node was thought to be caused by apoptosis induced by the Fas-Fas ligand system. We hypothesize that the apoptosis was strongly related to the pathogenesis of this disease.

Adult↗
PubMed1999

Brain natriuretic peptide (BNP) and cyclic guanosine monophosphate (cGMP) levels in normal pregnancy and preeclampsia.

OBJECTIVE: Our purpose was to evaluate plasma levels of brain natriuretic peptide (pBNP) and cyclic guanosine monophosphate (pcGMP) in preeclamptic patients and controls. STUDY DESIGN: Blood samples were obtained from 35 patients with preeclampsia and from the same women during the subsequent puerperal period. The control group consisted of normotensive pregnant women, matched with the patients for age, gestational age, and parity. The concentrations of pBNP and pcGMP were determined by the RIA method. Statistical analysis was performed using the Mann-Whitney's U test. RESULTS: The pBNP level in the preeclampsia group was significantly increased, to 7-fold that of the control group. The pcGMP level was 50% higher in the preeclampsia group than in the control group, but this was not significant. Both the pBNP level and the pcGMP level in the puerperal period did not significantly differ between the patients and the controls. CONCLUSION: The pBNP concentrations increased in the preeclamptic women, and then these compensations were normalized in the puerperal period.

Adult↗
PubMed1999

Infection of human respiratory submucosal glands with rhinovirus: effects on cytokine and ICAM-1 production.

To further understand the early biochemical events that occur in infected surface epithelium, we developed for the first time a model in which a respiratory submucosal gland cell population can be infected with rhinovirus (RV). Viral infection was confirmed by demonstrating with PCR that viral titers in supernatants and lysates from infected cells increased with time. Infection by RV14 upregulated the expression of intercellular adhesion molecule-1 (ICAM-1) mRNA, the major RV receptor, on submucosal gland cells, and it increased production of interleukin (IL)-1alpha, IL-1beta, IL-6, IL-8, tumor necrosis factor-alpha, and granulocyte-macrophage colony-stimulating factor in supernatants. Antibodies to ICAM-1 inhibited RV infection of submucosal gland cells and decreased the production of cytokines after RV infection. Both IL-1alpha and IL-1beta upregulated ICAM-1 mRNA expression and increased susceptibility to RV infection, whereas other cytokines failed to alter ICAM-1 mRNA expression. Furthermore, neutralizing antibodies to IL-1alpha and IL-1beta significantly decreased the viral titers in supernatants and ICAM-1 mRNA expression after RV infection, but a neutralizing antibody to tumor necrosis factor-alpha was without effect. These findings suggest that respiratory submucosal gland cells play an important role in the initial stages of inflammation and provide useful insights into the pathogenesis of RV infection.

Adult↗
PubMed1999

A case of constrictive pericarditis with local thickening of the pericardium without manifest ventricular interdependence.

This is the first case report of postsurgical constrictive pericarditis confined to the left ventricle in which the majority of diagnosis tests were not indicative of the disease. A 50-year-old woman with a past history of mitral valve replacement was admitted for right heart failure. Cardiac catheterization showed impaired diastolic filling but lacked the characteristic ventricular interdependence recently reported to be specific for the disease, without manifest radiological appearance of pericardial thickening. However, a new technique using magnetic resonance tagging cine revealed pericardial adhesion, limited to the left ventricle, which was confirmed during pericardiectomy. After the surgery, right heart failure and diastolic filling abnormality disappeared with restoration of normal heart pressures.

Blood Flow Velocity↗
PubMed1999

Study on pancreatic insufficiency (chronic pancreatitis) and steatorrhea in Japanese patients with low fat intake.

The incidence of steatorrhea is said to be lower and its grade milder in Japanese because their fat intake is lower than that of Europeans and Americans. Failure to take this into account creates difficulties when attempting to compare data on pancreatic exocrine insufficiency in different countries. The authors examined the incidence and grade of steatorrhea in Japanese chronic pancreatitis (CP) patients whose daily fat intake was <40 g (25 patients) or > or =40 g (35 patients). In addition, 23 CP patients with steatorrhea and daily fecal fat excretion > or =5 g were given a pancreatic enzyme preparation at a dose 3-8 times higher than the usual dose to investigate its effect on fecal fat excretion. Among CP patients whose fat intake was <40 g, the incidence of fecal fat excretion <5 g was 56% and that of fecal fat excretion > or =10 g (severe steatorrhea) was 8%. In CP patients whose fat intake was > or =40 g, the incidences were 27.9 and 34.9%, respectively; a significant increase in the number of affected patients was noted when fat intake was > or =40 g. The fat absorption rate was 76.2% among patients whose fat intake was <40 g and 77.8% among patients whose fat intake was > or =40 g, revealing no significant difference between the two groups. The proportion of CP patients whose fat absorption rate < or =80% was 32% at a fat intake <40 g and 39% at a fat intake > or =40 g, revealing no significant difference between the two groups.

Adult↗
PubMed1999

Protective effects of heme oxygenase-1 against oxidant-induced injury in the cultured human tracheal epithelium.

To examine whether increases in heme oxygenase (HO)-1 activity have protective effects on the oxidant-induced injury of airway epithelial cells, human tracheal epithelial cells were cultured on a porous filter membrane, and electrical conductance (G) and mannitol flux across epithelial membrane were measured with Ussing's chamber methods and D-[(3)H]mannitol, respectively. Hydrogen peroxide (H(2)O(2); 1 mM) increased G with time from the baseline value of 6.0 +/- 0.6 to 17.8 +/- 0.9 mS/cm(2) at 6 h after administration (P < 0.001). Likewise, H(2)O(2) significantly increased mannitol flux through the cultured epithelium (P < 0.01). Pretreatment of cultured epithelial cells with hemin (10 microM; 8 h) or interleukin (IL)-1beta (10 ng/ml; 16 h) completely inhibited increases in G and mannitol flux induced by H(2)O(2). Tin protoporphyrin IX (50 micrometer) and zinc protoporphyrin IX (10 microM), inhibitors of HO-1, reduced hemin-induced and IL-1beta-induced inhibitory effects. Hemin treatment increased HO-1 messenger RNA expression, HO-1 protein production, and HO activity and bilirubin content as well as ferritin content in the cultured epithelial cells. Pretreatment with hemin and desferoxamine, which, like ferritin, can bind iron, inhibited H(2)O(2)-induced increases in G and mannitol permeability. Although exogenous bilirubin mimicked hemin-induced inhibitory effects, exogenous apoferritin failed to inhibit H(2)O(2)-induced effects on G and mannitol permeability. These findings suggest that HO-1 induction provides protection against H(2)O(2)-induced injury of the cultured human airway epithelial cells in part via the HO-bilirubin pathway.

Adult↗
PubMed1999

Levels of 24,25-dihydroxyvitamin D3, 25-hydroxyvitamin D3 and 25-hydroxyvitamin D3 3-sulphate in human plasma.

The concentrations of (24R)-24,25-dihydroxyvitamin D3[24,25(OH)2D3], 25-hydroxyvitamin D3[25(OH)D3] and its 3-sulphate [25(OH)D3(3)S] in the plasma of healthy subjects, patients with chronic renal failure, patients with climacteric syndrome, pregnant women and foetuses were determined using the enzyme-linked immunosorbent assay and high-performance liquid chromatography. 25(OH)D3(3)S was not detected in about one-third of the plasma samples from patients with chronic renal failure (n = 26). The three metabolites in maternal plasma reached the highest levels in the second trimester of pregnancy followed by a decrease to the values obtained in the first trimester. Older healthy women (age range 44-71 years) showed higher levels of 24,25(OH)2D3 and 25(OH)D3 in the plasma than did young healthy women (age range 21-29 years), whereas no clear difference was observed between the older healthy women and patients with climacteric syndrome. The level of 25(OH)D3(3)S in the plasma was higher in the latter patients than in healthy women.

24,25-Dihydroxyvitamin D 3↗
PubMed1999

Two-stage repair for aortic regurgitation complicated by severe coarctation of the thoracoabdominal aorta due to Takayasu's arteritis.

Takayasu's arteritis is a rare inflammatory aortoarteritis of unknown etiology and causes stenoocclusive disease of the aorta and its branches as well as aortic regurgitation. A surgical case of Takayasu's arteritis is presented. A 56-year-old female exhibited aortic regurgitation complicated by severe coarctation of the thoracoabdominal aorta due to Takayasu's arteritis. In this case, a 2-staged repair, consisting of an axillofemoral bypass and an aortic valve replacement, was successfully performed.

Aortic Coarctation↗
PubMed1999

Primary leiomyosarcoma of the left atrium.

A 69-year-old woman with symptoms of congestive heart failure had a left atrial leiomyosarcoma, an extremely rare cardiac tumor, which obstructed the mitral valve and pulmonary veins. Surgical resection was performed, but no other adjuvant therapy was administered because the patient refused it. Recurrence of the tumor occurred soon after surgery and the patient died 81 days postoperatively.

Aged↗
PubMed1999

Ultrastructural changes and immunohistochemical localization of nitric oxide synthase, advanced glycation end products and NF-kappa B in aorta of streptozotocin treated Mongolian gerbils.

To evaluate the relationship among the induction of nitric oxide synthase (NOS), advanced glycation end products (AGEs) and NF-kappa B for vascular damage in hyperglycemia, we injected Mongolian gerbils intravenously with 150 mg/kg streptozotocin (STZ) and observed over the next one year the resulting aortic changes by immunohistochemical and electron microscopical techniques. After STZ treatment, hyperglycemia was confirmed and body weight transiently decreased. Morphological observation revealed no remarkable changs in vascular endothelial cells or vascular smooth muscle cells in the aorta at one week after STZ administration. After 4 weeks increased collagen fibrils were observed in the pericellular spaces of media. At one year after STZ administration, increased collagen fibrils and thickened elastic fibers were found around the vascular smooth muscle cells with vacuolization and increased cytoplasmic organellae compared with non-treated animals of the same age. Immunohistochemically endothelial constitutive NOS (ecNOS) was localized in the endothelium of the aorta of Mongolian gerbils. At one year after STZ administration, the reaction products of iNOS, AGEs and NF-kappa B in vascular endothelial cells and smooth muscle cells were much more greatly increased than at one week and 4 weeks. After STZ administration, the localization of NOS, AGEs and NF-kappa B was observed in the aorta, which suggests these factors play important roles in the pathogenesis of vasculopathy in diabetes mellitus.

Animals↗