Search PubMed⌕ Search

Biomedical subjects

H Uyama

Publications and source records attributed to H Uyama.

At least 19 recordsLinked to original sources
PubMed2001

Artificial urushi.

A new concept for the design and laccase-catalyzed preparation of "artificial urushi" from new urushiol analogues is described. The curing proceeded under mild reaction conditions to produce the very hard cross-linked film (artificial urushi) with a high gloss surface. A new cross-linkable polyphenol was synthesized by oxidative polymerization of cardanol, a phenol derivative from cashew-nut-shell liquid, by enzyme-related catalysts. The polyphenol was readily cured to produce the film (also artificial urushi) showing excellent dynamic viscoelasticity.

Journal Article↗
PubMed2001

In vitro biosynthesis of polyesters.

In vitro synthesis of polyesters using isolated enzymes as catalyst via non-biosynthetic pathways is reviewed. In most cases, lipase was used as catalyst and various monomer combinations, typically oxyacids or their esters, dicarboxylic acids or their derivatives/glycols, and lactones, afforded the polyesters. The enzymatic polymerization often proceeded under mild reaction conditions in comparison with chemical processes. By utilizing characteristic properties of lipases, regio- and enantioselective polymerizations proceeded to give functional polymers, most of which are difficult to synthesize by conventional methodologies.

Chemical Engineering↗
PubMed2001

Enzymatic synthesis of cross-linkable polyesters from renewable resources.

Enzymatic synthesis of a new class of cross-linkable polyesters has been achieved. Polymerization of divinyl sebacate and glycerol using Candida antarctica lipase as catalyst in the presence of unsaturated higher fatty acids produced the polyesters having an unsaturated group in the side chain. The polyester was subjected to hardening by cobalt naphthenate catalyst or thermal treatment, yielding cross-linked transparent film.

Candida↗
PubMed2001

Enhanced expression of plasminogen activator inhibitor 1 in patients with nephrotic syndrome.

Hypercoagulability is present in patients with nephrotic syndrome. However, alterations in coagulation and fibrinolysis reflected in the glomeruli and urine are not fully understood. We examined plasma and urine concentrations of tissue-type plasminogen activator (tPA) and type 1 plasminogen activator inhibitor (PAI-1) in 33 patients with nephrotic syndrome (nephrotic group). We compared these concentrations with the concentrations in 30 nonnephrotic patients with chronic glomerulonephritis (nonnephrotic group) and with the concentrations in 30 healthy volunteers (control group). We also examined fibrin/fibrinogen degradation products in serum and urine and plasma D-dimers. The expression of tPA and PAI-1 was examined in isolated glomeruli using RT-PCR methods. Deposition of fibrinogen/fibrin-related antigen was observed by direct immunofluorescence. The incidence of fibrinogen/fibrin-related antigen deposition in the nephrotic group was significantly higher than that in the nonnephrotic group. The concentrations of fibrin/fibrinogen degradation products in serum and urine and of plasma D-dimers were significantly elevated in the nephrotic group as compared with the nonnephrotic and control groups. The plasma concentrations of tPA in the nephrotic group were significantly higher than those in the control group. The urinary excretion of tPA in the nephrotic group was also significantly higher than in the nonnephrotic and control groups. The urinary excretion of PAI-1 in the nephrotic group was higher than that in the control group. The ratio of PAI-1 mRNA to tPA mRNA in glomeruli was increased in the nephrotic group as compared with the nonnephrotic group. These results indicate that the fibrinolytic activity is increased in patients with nephrotic syndrome despite urinary losses of tPA. However, a relatively enhanced expression of PAI-1 may be involved in the intraglomerular fibrinogen/fibrin-related antigen deposition seen in nephrotic syndrome.

Adolescent↗
PubMed2001

[Two cases of exercise-induced acute renal failure with idiopathic renal hypouricemia].

Acute renal failure without oliguria developed in a 25-year-old male and a 19-year-old male after exercise. Marked hypouricemia became apparent during improvement of their renal function. Increased excretion of uric acid into the urine, increased fractional excretion of uric acid(clearance ratio of uric acid against creatinine), and normal concentration of plasma xanthine and hypoxanthine were observed in both cases. Probenecid and pyrazinamide loading test suggesting decreased reabsorption of uric acid in the proximal convoluted tubules revealed that presecretory reabsorption defect of uric acid resulted in the hypouricemia in both cases. These two cases were diagnosed as having idiopathic renal hypouricemia.

Acute Kidney Injury↗
PubMed2000

Enzymatic synthesis of polyesters from lactones, dicarboxylic acid divinyl esters, and glycols through combination of ring-opening polymerization and polycondensation.

Enzymatic copolymerization of lactones, divinyl esters, and glycols has been performed using lipase as catalyst to produce ester copolymers. The monomers used in this study were 12-, 13-, and 16-membered lactones, divinyl esters of adipic and sebasic acids, and alpha,omega-glycols. Candida antarctica and Pseudomonas cepacia lipases showed relatively high catalytic activity for the present copolymerization, yielding the copolymer having relatively high molecular weight in moderate yields. From 13C NMR analysis, the resulting product was not a mixture of homopolymers, but a copolymer derived from the monomers. NMR data and reaction monitoring results indicate that two different modes of polymerization, ring-opening polymerization and polycondensation, simultaneously take place through enzyme catalysis in one-pot to produce ester copolymers.

Catalysis↗
PubMed2000

Lipase-catalyzed degradation of polyesters in organic solvents. A new methodology of polymer recycling using enzyme as catalyst.

Enzymatic hydrolytic degradation of aliphatic polyesters in organic solvents has been examined. The degradation of poly(epsilon-caprolactone) took place using Candida antarctica lipase as catalyst in toluene at 60 degrees C to give oligomers with molecular weight of less than 500. The degradation behavior catalyzed by lipase was quite different than an acid-catalyzed degradation (random bond cleavage of polymer). After the removal of the solvent from the reaction mixture, the residual oligomer was polymerized in the presence of the same catalyst of lipase. These data provide a basic concept that the degradation-polymerization could be controlled by presence or absence of the solvent, providing a new methodology of plastics recycling.

Candida↗
PubMed2000

Chemoselective oxidative polymerization of m-ethynylphenol by peroxidase catalyst to a new reactive polyphenol.

Enzymatic oxidative polymerization of m-ethynylphenol possessing two reactive groups, phenol and acetylene moieties, was carried out in aqueous methanol under air. Horseradish peroxidase and hydrogen peroxide were used as catalyst and oxidizing agent, respectively. 1H NMR and IR analysis showed that only the phenolic moiety was polymerized to produce the polymer having the ethynyl group in the side chain. The reaction of the monomer using a copper/amine catalyst, a conventional catalyst for oxidative coupling, exclusively produced a diacetylene derivative. From these data, it was found that the peroxidase catalysis induced the chemoselective polymerization of the monomer. The resulting polymer was converted to carbonized polymer in a much higher yield than enzymatically synthesized poly(m-cresol) and is expected to have potential applications as a reactive starting polymer.

Catalysis↗
PubMed1998

Discordance between retinopathy and nephropathy in type 2 diabetes.

The aim of this study was to investigate the relationship between the grade of retinopathy and the severity of glomerular lesions in patients with type 2 diabetes and to describe 5 patients without diabetic retinopathy for whom renal biopsy specimens demonstrated advanced diabetic nephropathy. A total of 221 patients with type 2 diabetes (139 males and 82 females) who consectively underwent renal biopsy between 1982 and 1996 were investigated. The severity of diffuse glomerular lesions was graded using the criteria of Gellman and coworkers, and diabetic retinopathy was classified as absent, nonproliferative, or proliferative. The incidence of advanced nephropathy without retinopathy for all 221 cases was 2.3%. Advanced nephropathy was present in 5 of the 122 (4.1%) patients without retinopathy. These 5 patients were all males and aged 50-70 (mean 61) years. Their clinical characteristics were not uniform, and no special clinical features distinguished the patients who were regarded as having possible advanced nephropathy without retinopathy. In our study, although concordance of retinopathy and nephropathy is relatively common, a little discordance was pronounced in Japanese type 2 diabetic patients. Our findings are consistent with the hypothesis that there are important differences in some aspects of the pathogenesis of retinopathy and nephropathy.

Aged↗
PubMed1997

Reversible glomerular hypertrophy in adult patients with primary focal segmental glomerulosclerosis.

The present study was performed to assess the pathogenetic role of glomerular hypertrophy in patients with primary focal segmental glomerulosclerosis (FSGS). We studied 14 patients with FSGS by morphometry. In seven patients, minimal change nephrotic syndrome (MCNS) was diagnosed on the first renal biopsy, but FSGS was diagnosed on the second biopsy (MCNS-FSGS group). Seven other patients with FSGS on the first biopsy underwent second biopsies while in remission (FSGS-R group). Biopsy results were compared with biopsies from 10 patients with MCNS and seven control subjects. Nonsclerotic glomeruli were examined. The mean glomerular tuft area, whole glomerular area, and number of mesangial cells were significantly increased in both biopsies from the MCNS-FSGS group and in the first biopsies obtained during the nephrotic stage of the FSGS-R group, compared with control subjects and patients with MCNS. Biopsies from FSGS patients in remission showed that the mean glomerular tuft area and number of mesangial cells were significantly decreased. The fractional extracellular matrix area (extracellular matrix area/glomerular tuft area) and mesangial cell density (mesangial cell number/glomerular tuft area) in FSGS during both nephrotic and remission stages were the same as those in control subjects and patients with MCNS. The present study suggests that glomerular hypertrophy precedes the development of glomerulosclerosis in FSGS and is reversible when patients are in remission. These features support the pathogenetic importance of glomerular hypertrophy in patients with primary FSGS.

Adult↗
PubMed1997

[An elderly patient with purpura nephritis that appeared after extracorporeal shock wave lithotripsy].

We report a 63-year-old male patient with purpura nephritis, which appeared 7 days after extracorporeal shock wave lithotripsy (ESWL). He was referred to our clinic because of a petechial rash on both lower extremities, pretibial edema and massive proteinuria. Urinalysis showed proteinuria and hematuria and some hyaline casts. A 24-hour urine sample contained 5.0 g of protein. Renal function on admission was decreased: serum creatinine was 1.5 mg/dl and creatinine clearance, 21 ml/min. Immunoserological tests demonstrated an increase in serum IgA (424.3 mg/dl). A skin biopsy revealed leukocytoclastic vasculitis. A renal biopsy showed endocapillary proliferation in a diffuse, but segmental fashion. However, no crescent formation was seen. Immunofluorescence microscopy disclosed mesangial staining for IgA and C3. Electron microscopy demonstrated severe injury to endothelial and epithelial cells: detachment of endothelial and epithelial cells, foot process effacement and macrophage infiltration. Electron-dense deposits were observed in the subendothelial and paramesangial areas. Because renal function was deteriorating rapidly, methylprednisolone pulse therapy and immunosuppressive treatment were implemented. Treatment was effective and the patient's renal function and proteinuria improved remarkably. The electron microscopic findings in this case of purpura nephritis seemed to be more severe than usual, suggesting that ESWL may aggravate glomerular damage.

Drug Administration Schedule↗
PubMed1996

Alterations in extracellular matrix components and integrins in patients with preeclamptic nephropathy.

The glomerular features of patients with preeclampsia consist of swelling of endothelial cells, subendothelial deposits of incompletely defined material, and thickening of the capillary walls. These abnormalities are thought to resolve in the postpartum period. The distribution of extracellular matrix (ECM) components and integrins was investigated in 10 such patients. Frozen sections and paraffin-embedded sections were stained with antibodies to type IV collagen, laminin (LN), fibronectin (FN), vitronectin (VN), tenascin (TN), fibronectin receptor (FNR), and vitronectin receptor (VNR). In preeclamptic nephropathy, the accumulation of type IV collagen, LN, FN, TN, and FNR was observed in the thickened capillary walls, particularly in the subendothelial layer and, to some extent, in the mesangium. However, deposits of VN were sparse and the distribution of VNR was similar to that in normal kidney. In segmental sclerotic lesions, the amounts of type IV collagen, LN, FN, VN, and TN were increased, whereas those of FNR and VNR were markedly decreased. These results suggest that the materials deposited in the subendothelial space consist of ECM components as well as of plasma-derived proteins, and that the deposition of ECM components and of FNR may be involved in the development and the reparative process of the characteristic glomerular lesions. The formation of sclerotic lesions was linked to the accumulation of ECM components, but not to an interaction with integrins.

Adult↗
PubMed1996

Diet-induced hypercholesterolemia increases endothelin-1 release by aortic endothelial cells.

Our previous studies demonstrated the morphological heterogeneity of endothelial cells (ECs) and the emergence of large multinucleated ECs in human and animal atherosclerotic lesions. To investigate the functional alteration of ECs in diet-induced atherosclerosis, immunoreactive endothelin-1 (irET-1) release by ECs of the rabbit aorta was correlated with scanning electron microscopy. Rabbits were fed a cholesterol diet for 12 weeks: by scanning electron microscopy, the area of ECs in the aorta increased in the hypercholesterolemic (HC) group as atherosclerosis progressed. Cultured ECs of the HC group released significantly more irET-1 than ECs of the control. The plasma irET-1 level was also elevated in the HC group. The results obtained suggest that accelerated secretion of ET-1 by ECs contributes to the development of atherosclerotic vascular lesions.

Animals↗
PubMed1996

Clinical and morphological predictors of renal outcome in adult patients with focal and segmental glomerulosclerosis (FSGS).

In this retrospective study, we examined 35 adult patients with biopsy-proven, primary focal and segmental glomerulosclerosis (FSGS) and nephrotic syndrome to determine whether any of the clinical and morphological features of FSGS were associated with a higher risk of a poor renal outcome. Clinical factors assessed were the age, sex, amount of urinary protein, and presence of microscopic hematuria, hypertension and renal dysfunction at onset in each patient. Morphological parameters included the number of segmental sclerosis and global sclerosis, sclerosis score, location of segmental sclerosis, mean glomerular diameter, grade of tubulo-interstitial changes, and presence of vascular lesions. Twenty-three patients (66%) were in complete or incomplete (partial) remission, and 12 (34%) were non-responders at the end of follow-up. On univariate analysis, the age at onset, sclerosis score, mean glomerular diameter, and grade of tubulo-interstitial changes in no response were significantly greater than those parameters in remission. Multivariate logistic regression analysis revealed that the degree of tubulo-interstitial changes and mean glomerular diameter were independent risk factors for a poor renal outcome. These findings suggest that the estimation of these latter two parameters allows the nephrologist to predict the probable course and prognosis of an adult with FSGS. Intensive and prolonged therapy is recommended for patients without these two morphological features.

Adult↗
PubMed1995

[A case of polyarteritis nodosa presenting with multiple intrarenal aneurysms and accelerated hypertension].

A twenty-one-year-old male was admitted to our hospital because of hypertension and proteinuria. He had felt general fatigue and low grade fever for one month. Blood pressure was 180/120 mmHg on admission. Laboratory findings showed 3+ proteinuria and 1+ occult blood in urinalysis; an accelerated erythrocyte sedimentation rate (ESR) of 39 mm/hr; elevation of LDH to 755 IU/l. Antinuclear antibody was positive with a titer of 1: 160, with a speckled pattern. Plasma renin activity and serum aldosterone were markedly elevated to 25.8 ng/ml/hr and 585.3 pg/ml, respectively. Renal function had declined mildly; endogenous creatinine clearance was 60 ml/min. Renal arteriogram demonstrated multiple intrarenal aneurysms in the bilateral kidneys. Aneurysms, 5-8 mm in diameter were located in the arteries from the interlobar to interlobular region. He was diagnosed as having polyarteritis nodosa (PN) and was then treated with 20 mg/day of prednisolone and monthly pulse therapy of cyclophosphamide. After steroid, cyclophosphamide and anti-hypertensive therapy, he became well and had normal blood pressure. The patient was considered a rare case of PN with multiple intrarenal aneurysms and accelerated hypertension. We discuss aneurysms in PN and accelerated or malignant hypertension documented in the literature.

Adult↗