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Biomedical subjects

K Sakurai

Publications and source records attributed to K Sakurai.

At least 37 records · Page 2Linked to original sources
PubMed2001

Further evidence for the gelation ability-structure correlation in sugar-based gelators.

Eight methyl glycosides of 4,6-O-benzylidene derivatives of the monosaccharides D-glucose, D-mannose, D-allose and D-altrose were synthesized to systematically study the effect of small configurational changes on the ability to gelate organic solvents. Among the beta anomers, only the D-mannose glycoside exhibits a strong gelation ability, whereas in the alpha-series the D-glucose and D-mannose derivatives act as versatile gelators. Also, as a general rule we found that the beta anomers possess a higher ability to gelate solvents than the alpha anomers. The gelation properties are discussed on the basis of SAXS, FTIR, differential scanning calorimetric (DSC) measurements and scanning electron microscopy (SEM) observations. The temperature-dependent SAXS measurements were carried out to elucidate the sol-gel transition temperature. The present study emphasizes that the saccharide family provides, not only valuable information of the structural requirements for the design of new gelators, but also for molecular assembly systems in general.

Carbohydrate Conformation↗
PubMed2001

Mechanisms of hydrogen peroxide-induced relaxation in rabbit mesenteric small artery.

The effects of hydrogen peroxide were studied on isolated rabbit mesenteric small artery; rabbit superior mesenteric artery and mouse aorta were also studied as reference tissues. For mesenteric small artery, hydrogen peroxide (1 to 100 microM) relaxed a norepinephrine-stimulated artery in a concentration-dependent manner. The relaxation was not significantly affected by removal of the endothelium and was less pronounced in arteries contracted with high-KCl solution plus norepinephrine than in those contracted with norepinephrine alone. The relaxation response to hydrogen peroxide was increased by isobutylmethylxanthine and zaprinast, inhibited by diclofenac, methylene blue and dithiothreitol and unaffected by atropine, tetraethylammonium, superoxide dismutase, deferoxamine, dimethyl sulfoxide or the Rp stereoisomer of adenosine cyclic monophosphothioate. Hydrogen peroxide shifted concentration-contractile response curves for norepinephrine to the right and downwards. Norepinephrine and caffeine elicited a transient, phasic contraction of the mesenteric small artery exposed for 0.5, 1 and 2 min to a Ca2+-free solution. Hydrogen peroxide inhibited the norepinephrine-induced contraction, and to a lesser extent the caffeine-induced contraction, and verapamil did not alter the contraction to norepinephrine. These pharmacological properties of hydrogen peroxide were similar to those of 8-bromo cGMP; 8-bromo cGMP inhibited more potently the norepinephrine-induced than the KCl-induced contraction and the contraction elicited by norepinephrine in Ca2+-free solution. The present results suggest that hydrogen peroxide induces endothelium-independent relaxation of the rabbit mesenteric small artery precontracted with norepinephrine. The effects of hydrogen peroxide may be at least in part mediated by cGMP and cyclooxygenase products in the vascular smooth muscles now used.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed2001

A trial of oolong tea in the management of recalcitrant atopic dermatitis.

BACKGROUND: Mild cases of atopic dermatitis (AD) generally improve with standard treatment. However, standard treatment fails many patients with recalcitrant AD skin lesions. Study results in animal models have demonstrated that the administration of tea (ie, green, black, or oolong) has suppressed type I and type IV allergic reactions. OBJECTIVE: To test the effectiveness of oolong tea in the treatment of recalcitrant AD. PATIENTS: Although 121 patients with recalcitrant AD were enrolled in the study, 118 patients completed the open study. METHODS: Patients were asked to maintain their dermatological treatment. However, they were also instructed to drink oolong tea made from a 10-g teabag placed in 1000 mL of boiling water and steeped for 5 minutes. This amount was then divided into 3 equal servings and 1 serving was drunk daily after 3 regular meals. Photographs of 2 or 3 representative lesion sites were taken at baseline and at 1 and 6 months and the severity of pruritus was assessed on a 6-point Lickert-like scale ranging from markedly improved (>50% improvement) to worsened. RESULTS: After 1 month of treatment 74 (63%) of the 118 patients showed marked to moderate improvement of their condition. The beneficial effect was first noticed after 1 or 2 weeks of treatment. A good response to treatment was still observed in 64 patients (54%) at 6 months. CONCLUSION: The therapeutic efficacy of oolong tea in recalcitrant AD may well be the result of the antiallergic properties of tea polyphenols.

Adolescent↗
PubMed2001

Polysaccharide-polynucleotide complexes (IV): antihydrolysis effect of the schizophyllan/poly(C) complex and the complex dissociation induced by amines.

Polymer complexes formed by schizophyllan and poly(C) showed a unique antihydrolysis effect when poly(C) was subjected to hydrolysis under basic conditions. The complexation reduced the hydrolysis rate to 80% of the control (i.e., poly(C) itself). However, when we added oligoamines with the intention of catalyzing the hydrolysis, the oligoamines induced dissociation of the complex instead of acceleration of the hydrolysis.

Amines↗
PubMed2001

Cesarean section in a patient with syringomyelia.

PURPOSE: To describe the anesthetic management of Cesarean section in a patient with syringomyelia. CLINICAL FEATURES: A 27-yr-old pregnant woman with syringomyelia was scheduled to undergo elective Cesarean section. At the age of 25 yr, she had begun to experience headaches, and at the age of 26 yr, a diagnosis of syringomyelia of the upper spinal cord was made on the basis of magnetic resonance imaging findings. No symptoms other than headache were noted preoperatively. General anesthesia was used for the Cesarean section. After the administration of 1 mg vecuronium as a priming dose, 5 mg vecuronium were injected. At the onset of clinical muscle weakness, 225 mg thiamylal were promptly administered as the induction agent and the patient was intubated (timing principle with priming method) and pressure on the cricoid cartilage applied to prevent regurgitation of stomach contents. Anesthesia was maintained with oxygen, nitrous oxide and isoflurane at a low concentration. Mild hyperventilation was used throughout the procedure. Anesthesia and surgery proceeded without any problem, response to vecuronium was clinically normal and recovery was uneventful. Neurological status remained normal. CONCLUSION: We report the safe use of general anesthesia for Cesarean section in a patient with syringomyelia. Precautions were taken to avoid increases in intracranial pressure and our patient experienced no untoward neurologic event.

Adult↗
PubMed2001

Comparison of perceptional nasal obstruction with rhinomanometric and acoustic rhinometric assessment.

Perception of nasal stuffiness, together with rhinomanometric and acoustic rhinometric assessments were evaluated before and after nasal and/or sinus surgery in 50 Japanese adult patients. Nasal resistance on both expiration and inspiration correlated well with the patients' perceptions (P<0.05). Nasal volumes (0-4 cm and 0-7 cm) obtained from acoustic rhinometry measurements also correlated well with perception (P<0.05). No significant relationships were found between rhinomanometric and acoustic rhinometric results. Perceptional nasal obstruction, rhinomanometric and acoustic rhinometric results (except for the sectional areas at the I-notch) improved significantly after the operations. Rhinomanometry and acoustic rhinometry are valuable methods for assessing nasal stuffiness, but we must take account of the differences between the two methods.

Adult↗
PubMed2001

Two competing mechanisms underlying neon color spreading, visual phantoms and grating induction.

Neon color spreading is closely related to the photopic visual phantom illusion, since these two completion phenomena are characterized by in-phase lightness induction, and the only difference in the stimulus configuration is the difference in the inducer height. This idea was supported by the present study. Neon color spreading showed almost the same function of critical spatial frequency as photopic visual phantoms (Experiment 1), and the critical spatial frequency was constant as the inducer height was changed (Experiment 2). We also examined the relationship between neon color spreading and grating induction (characterized by counterphase lightness induction) in critical spatial frequency (Experiment 3) and in magnitudes of lightness induction (Experiment 4) as a function of the inducer height. The inducer height at which in-phase (neon color spreading) appearance gave way to counterphase (grating) induction was approximately 0.1 deg. These results suggest that neon color spreading shares a common neural mechanism with the photopic visual phantom illusion and that this mechanism is different from, and competes with, the mechanism of grating induction.

Color Perception↗
PubMed2001

Protective effects of a protein-bound polysaccharide, PSK, on Candida albicans infection in mice via tumor necrosis factor-alpha induction.

We investigated the protective mechanism of a protein-bound polysaccharide, PSK, against lethal infection with Candida albicans (C. albicans) in mice. (1) In BALB/c mice inoculated intravenously with C. albicans, the intraperitoneal (ip) administration of PSK increased survival rates and prolonged the survival period depending on the time of administration, the dosage, and the size of fungal inoculum; the maximal effect was obtained when PSK 250 mg/kg was ip administered to mice 24 h before inoculation of 1 x 10(6) C. albicans (30 days survivors showed 60% and the mean survival period of mice with fatal infection increased 209%). (2) The protective effect of PSK was significantly decreased in mice treated with cyclophosphamide or carrageenan, or in mice treated previously with anti-tumor necrosis factor-alpha (TNF-alpha) antibody. (3) The administration of PSK significantly enhanced the expression of TNF-alpha gene in spleen and increased leukocyte functions from 6 h to 1 day after inoculation. (4) When the PSK fraction subjected to hydrolysis with beta1-3 glucanase or hydrazine was used instead of PSK, the anti-fungal activities were significantly decreased. These findings suggested that the protective effect of PSK on lethal C. albicans infection in mice was mainly produced via TNF-alpha functions, and that beta 1-3 glucan and protein moiety in PSK molecule were involved in the expression of the activities.

Animals↗
PubMed2001

Polysaccharide--polynucleotide complexes. 2. Complementary polynucleotide mimic behavior of the natural polysaccharide schizophyllan in the macromolecular complex with single-stranded RNA and DNA.

Schizophyllan is an extracellular polysaccharide consisting of a beta-1,3-D-glucan main chain and exists as a triple helix in water and as a single chain in dimethyl sulfoxide (DMSO). When the single chain of schizophyllan (s-SPG) was mixed with poly(C), poly(A), poly(dA), or poly(dT), they form a macromolecular complex. On the other hand, poly(G), poly(U), poly(I), poly(dG), and poly(dC) do not. This nucleotide specificity evidences that the hydrogen bonds are essential to form the complex, because the former nucleotides have an unoccupied hydrogen-bonding site and the latter ones use the hydrogen-bonding sites in the intramolecular aggregation (i.e., such as the G quartet for poly(G) and poly(dG) and the U hairpin for poly(U)). The hypochromic effect and the increment in the circular dichroism (CD) intensity are observed in accordance with the complex formation. These facts indicate that the base stacking is enhanced in the complex. The solvent-composition (DMSO/water) dependence demonstrates that the hydrophobic interaction is important to form the complex as well as the hydrogen-bonding interaction. With increasing temperature the complex dissociates cooperatively and the melting curve enables the thermodynamic parameters to be evaluated (delta H = -60 to 70 kcal mol-1 and delta S = -150 to 200 cal mol-1 K-1). These values are comparable with those for double helix DNA. Namely, the complex can be characterized by enhancement of the base stacking, cooperative dissociation, the similar thermodynamic parameters to DNA, and combination of the hydrogen-bonding and hydrophobic interactions to form the higher-order structure. These facts surprisingly coincide with characters of the double helix of DNA. In other words, the s-SPG molecule behaves as if it were a complementary polynucleotide chain for the corresponding polynucleotide. Furthermore, stoichiometric study suggested that the complex structure is a triple helix consisting of two s-SPG and one poly(C) or poly(A) chains.

Carbohydrate Conformation↗
PubMed2001

Mutation analysis of the NMDAR2B (GRIN2B) gene in schizophrenia.

NMDA receptor dysfunction may be involved in the pathophysiology of schizophrenia. Based on this hypothesis, we screened 48 Japanese patients with schizophrenia for mutations in the coding region of the NMDAR2B subunit gene (GRIN2B). An association study between the identified DNA sequence variants and schizophrenia was performed in 268 Japanese patients with schizophrenia and 337 Japanese control subjects. Eight single nucleotide polymorphisms were detected, all of which were synonymous. The association sample showed statistically significant excesses of homozygosity for the polymorphisms in the 3' region of the last exon in the patients with schizophrenia (P = 0.004) and higher frequency of the G allele of the 366C/G polymorphism (corrected P = 0.04) in the patients than in the controls. Although we did not detect NMDAR2B protein variants, our findings support the possibility that the GRIN2B gene or a locus in linkage disequilibrium with it may confer susceptibility to schizophrenia. Replication studies in independent samples are warranted.

Adult↗
PubMed2001

An autopsy case of pancreatic and ectopic nesidioblastosis.

We report an autopsy case of pancreatic and ectopic nesidioblastosis. A five-month-old Japanese girl was born at 35 weeks gestation, and showed clinical symptoms of hyper-insulinemic hypoglycemia before death. At autopsy a tumorous nodule was observed at the portion of the jejunum, 90 cm from Treitz's ligament. The nodule measured 30 x 20 x 20 mm. The ectopic pancreas, also revealed nesidioblastosis histologically. Immunohistologically, both nesidioblastoses were stained positive for chromogranin A, insulin, glucagon and somatostatin. The proliferating cell nuclear antigen (PCNA) and Ki-67 indices were less than 4% in the nesidioblastosis. To our knowledge, this is the first reported case of nesidioblastosis demonstrating proliferating activity with PCNA and Ki-67, and is the third reported case of nesidioblastosis arising in the pancreas and ectopic pancreas.

Choristoma↗
PubMed2001

Increased expression of cyclooxygenase-2 in human salivary gland tumors.

We examined the immunohistochemical localization of cyclooxygenase (COX)-2 in human salivary gland tumors. Thirty salivary gland adenomas (SGA), 40 salivary gland carcinomas (SGC) and 15 normal salivary glands (NSG) were studied. NSG showed restricted COX-2 staining only in the epithelial cells of salivary ducts. In contrast, COX-2 protein was detected in 27 cases of SGA (90%), except for three myoepitheliomas, and in all cases of SGC (100%) at various intensities and in various fashions. Thirteen SGA (43%) and 36 SGC (90%) cases showed strong COX-2 staining predominantly in tumor cells containing ductal components, as did serous and mucous acinic components of acinic cell carcinomas, mucoepidermoid carcinomas and mucinous carcinomas. These findings may suggest that COX-2 in salivary gland tumors is expressed in tumor cells derived from pluripotential ductal epithelium that can histologically develop into either serous or mucinous acinar cells.

Adenoma↗
PubMed2001

Transfusion transmitted virus infection in patients on maintenance haemodialysis and in hospital workers.

A newly discovered DNA virus, transfusion transmitted virus (TTV), was isolated from a post-transfusional hepatitis patient in Japan. A high prevalence (32-46%) of TTV infections in patients receiving maintenance haemodialysis (HD) has been reported but the occupational risk of TTV on HD units has not yet been determined. We determined the prevalence of TTV in workers in the same HD unit and the risk factors for TTV infection in HD patients, using logistic regression analysis. The prevalence of TTV DNA was 59.6% in 198 HD patients, significantly higher than that in the HD unit (13 of 39, 33.3%;P= 0.002) and non-HD healthcare workers (20 of 75, 26.7%; P= 0.001). A logistic regression analysis showed that male gender and negative test results for hepatitis G virus RNA were risk factors for TTV infection, but prior blood transfusion and duration of HD were not. Stepwise selection of multiple regression analysis showed that the presence of hepatitis C virus RNA was the only significant predictor for high serum ALT activity, and that the presence of TTV DNA was not. These results indicate that TTV is one of the prevalent human viruses transmissible either parenterally or nonparenterally in HD patients, but the occupational risk of TTV infection in HD unit workers is as low as in other healthcare workers. The pathogenic effects of TTV on the liver appear to be limited.

Adult↗
PubMed2001

Pathophysiologic phenotypes of Japanese subjects with varying degrees of glucose tolerance: using the combination of C-peptide secretion rate and minimal model analysis.

We tried to characterize the clinical features associated with glucose metabolism in the development of diabetes. Study subjects were glucose-tolerant subjects without a family history of diabetes (normal glucose tolerance [NGT]1 group, n = 15) and with a first-degree diabetes relative (NGT2, n = 9), 12 subjects with impaired glucose tolerance (IGT), and 13 subjects with type 2 diabetes mellitus (DM). The first phase C-peptide secretion (CS1), insulin sensitivity (Si), and glucose effectiveness (Sg) were assessed by the combination of C-peptide 2-compartment model and minimal model analyses. Using these parameters, each group was characterized: CS1 was decreased in NGT2 and IGT compared with NGT1 and further decreased in DM; Si was not different among NGT1, NGT2, and IGT, whereas Si was decreased in DM; CS1 x Si value was decreased in NGT2 compared with NGT1 and decreased in IGT, DM, progressively; Sg was decreased in IGT and DM compared with NGT1 and NGT2. CS1 x Si and Sg values could segregate each group distinctively, although it had a large variety of phenotypes. CS1 x Si value and Sg are assumed to represent the contributions of insulin-dependent and independent mechanisms to glucose tolerance, respectively, and thus, both mechanisms should play an important role in the characterization of pathophysiologic phenotypes of the subjects with various degrees of glucose tolerance.

Adult↗
PubMed2001

Common variable immunodeficiency with unusual vegetative lesions of the tongue and labial mucosa: a case report.

A case of common variable immunodeficiency with unusual vegetative lesions of the tongue and lower lip in a 28-year-old man is presented. The vegetative lesions developed over the preceding 10 months and clinically were suggestive of malignancy. The biopsy specimens showed no malignancy, and a bacterial culture of the tongue detected abundant Staphylococcus aureus. Combined treatment with a corticosteroid antibiotic ointment and povidone iodine rinse produced remarkable resolution of the lesions. Laboratory examination showed markedly decreased levels of serum immunoglobulins. Intravenous gamma globulin replacement therapy resulted in good control of infection and disappearance of the lesions.

Adult↗
PubMed2001

Similarity between Petter's effect and visual phantoms.

Here we draw attention to similarity between Petter's effect and the visual phantom illusion. Phantoms are visible when the spatial frequency of the inducing grating is low or the occluder is thin, whereas phantoms are invisible when the spatial frequency of the inducing grating is high or the occluder is thick. Moreover, phantoms are perceived in front of the occluder when they are visible, whereas the occluder is seen in front of the inducing gratings when phantoms are invisible. These characteristics correspond to Petter's effect, in which the thicker region tends to be perceived in front of the thinner region when two regions of the same lightness and of different sizes overlap, since 'thick' corresponds to low spatial frequency of the inducing grating or a thick occluder while 'thin' corresponds to high spatial frequency of the inducing grating or a thin occluder.

Depth Perception↗