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Biomedical subjects

H Sano

Publications and source records attributed to H Sano.

At least 433 records · Page 24Linked to original sources
PubMed1994

The influences of the buffer capacity of various substances on pH changes in dental plaque.

This study clarified the suitable pKa value for buffering substances against plaque pH fall in vitro and simultaneously estimated the effect of low molecular chitosan (LMCS) on plaque pH lowered by metabolized acids in vitro and in vivo. Five buffering substances with different pKa, aspartame (pKa: 7.8), phosphate buffer (7.1), LMCS (6.4), maleate buffer (6.2), and monofluorophosphate (4.8), were tested in this study. In the method using S. mutans cells, phosphate inhibited the pH fall from an initial pH of over 7.0, but phosphate exhibited no effect when the initial pH was 6.0. By the addition with lactic acid, LMCS and maleate exhibited more effective inhibition of the pH-fall than the others. These observations imply that pKa value is an important indicator of the ability of a buffering substance to reduce pH fall in dental plaque and that the optimum pKa value may be around pH 6.3. In the plaque pH measurement using ISFET electrode, LMCS showed an additional effect in inhibiting plaque pH fall following direct application of the glucose solution. The findings indicate that LMCS may be useful as a food additive to decrease the cariogenicity of foods.

Adult↗
PubMed1994

Effects of low molecular chitosan on pH changes in human dental plaque.

Effects of six kinds of low molecular chitosan (LMCS) on pH changes in dental plaque were compared in vitro and in vivo in order to clarify the relationship between their characteristics and effectiveness. Six LMCS with different molecular weights (MW) (500-3,000) and degrees of deacetylation (DAC) (50-95%) were prepared for this study. Evaluations using S. mutans cell suspensions in vitro showed that all samples had almost equal abilities to reduce pH fall in dental plaque. They were found to have no influence on the glycolytic activity of S. mutans. However, clinical evaluations of pH fall in dental plaque using an ion-sensitive field-effect transistor (ISFET) electrode showed unexpected results as follows; The most reduction in pH fall was obtained with the LMCS with a MW of 3,000 and a DAC of 50%, which had been presumed to be the most ineffective sample. The second ranked LMCS in this experiment had a MW of 500 and a DAC of 95%; it had been expected to be the most effective one. The findings indicated that LMCS has a high ability to inhibit pH fall in dental plaque and suggested that such properties as molecular weight and degree of deacetylation can have great influences upon its activity in clinical application.

Acetylation↗
PubMed1994

pH response of human dental plaque to chewing gum supplemented with low molecular chitosan.

The effects of low molecular chitosan (LMCS) on pH responses of human dental plaque following exposure to fermentable carbohydrates were investigated by an ion-sensitive field-effect transistor electrode system. After the plaque pH values were minimized by direct application of 5% glucose solution or consumption of sugared caramel, the subjects started chewing the test gums containing 0 (control), 1 or 3% (w/w) LMCS for three minutes. The pH response was monitored until it recovered to over pH5.5. In the case of the glucose solution, chewing 3% LMCS gum caused significantly more rapid pH recovery toward the resting level than did the control gum. Initial pH rising rate during gum chewing was faster with either of the two LMCS gums than with the control gum. In the case of caramel, additional effects of LMCS were observed numerically as LMCS content increased. The findings indicated that LMCS had a potential to promote recovery of plaque pH after acidogenic challenge and to maintain the plaque pH around neutrality.

Adult↗
PubMed1994

Estrous-related variations of blood pressure and heart rate in female rats.

In female rats, several biological variables change with a 4 or 5 day estrous cycle. To clarify whether blood pressure and heart rate show estrous-related changes, we measured three variables, i.e. mean arterial pressure (MAP), heart rate (HR) and spontaneous activity (ACT), using an implantable radiotelemetry transmitter and a computerized data collecting system non-invasively and chronically for more than 2 months. Under a 12-12 light-dark cycle, the three variables revealed clear daily variations and modulations by the estrous cycle which were most pronounced in the proestrous night. During the proestrous night, ACT showed a remarkable increase and a peak in the first half of the night, whereas MAP showed a gradual increase and a peak around midnight, and HR remained low without forming a peak. All modulations by the estrous cycle disappeared following bilateral ovariectomy. It is concluded that daily variations of blood pressure and heart rate are modulated according to the estrous cycle.

Animals↗
PubMed1994

[p53 expression in colorectal adenoma and early carcinoma].

Expression of p53 was studied immunohistologically in 25 adenomas, 46 cancers in adenoma, and 18 cancers without adenoma, which were obtained by endoscopic polypectomy or mucosal resection. Positive ratio of p53 expression was 100% in cancer without adenoma, 78.3% in cancer in adenoma, and 48% in adenoma. We divided the positive case of p53 expression to three staining patterns, poorly stained type, focal type and diffuse type. The diffuse type was most of cancer without adenoma. In each diagnostic group there was no significant colleration between sex, age, and shape of polyp and the staining pattern. But in cancer without adenoma, there was significant colleration between size of polyp and the staining pattern, and number of the diffuse type increased as the polyp size was larger. Consequently, it was suggested that p53 takes a role of cancerization from adenomas at every step.

Adenoma↗
PubMed1994

[Effect of angiotensin II on collagen metabolism in cultured rat cardiac fibroblasts: its relation to cardiac hypertrophy].

Hypertensive cardiac hypertrophy is associated with collagen accumulation in the myocardial interstitium. Myocardial fibrosis accounts for impaired myocardial stiffness and ventricular dysfunction. Although cardiac fibroblasts are responsible for the synthesis of fibrillar collagen, factors that regulate collagen synthesis in cardiac fibroblasts are not fully elucidated. The purpose of this study was to investigate the effect of angiotensin II (Ang II) on collagen synthesis by cultured rat cardiac fibroblasts. A 24-hour stimulation of cardiac fibroblasts with Ang II increased their collagen synthesis in a dose-dependent manner. This effect was blocked by the Ang II receptor antagonist, saralasin. Ang II neither affected the proportion of collagen types nor induced DNA synthesis. Basal collagen synthesis in cardiac fibroblasts from spontaneously hypertensive rats (SHR) was greater than that from normotensive Wistar-Kyoto rats. The responsiveness of collagen production to Ang II was significantly enhanced in cardiac fibroblasts from SHR. These results indicate stimulatory actions of Ang II on collagen synthesis in cardiac fibroblasts, enhanced collagen production in cardiac fibroblasts from SHR, and the hyperresponsiveness of cardiac fibroblasts from SHR to Ang II stimulation. Thus, Ang II may play an important role in collagen accumulation in hypertensive cardiac hypertrophy.

Angiotensin II↗
PubMed1994

[A case of unroofed coronary sinus with persistent left superior vena cava].

A 44-year-old female with left to right shunt and persistent left superior vena cava (PLSVC) suspected of unroofed coronary sinus defect with patent right SVC and innominate vein was treated surgically. PLSVC was ligated and coronary sinus ostium was closed with a EPTFE patch. Roof defect of coronary sinus was left open and allowed the coronary venous blood to drain into the left atrium. Patient recovered well and post-operative cardiac catheterization revealed no significant right to left shunt nor desaturation of arterial blood. In the correction of unroofed coronary sinus defect and PLSVC and no other intra-cardiac defect, ligation of PLSVC and closure of coronary sinus ostium was simple and effective, although it was not anatomically corrected.

Adult↗
PubMed1993

Corticotropin-releasing hormone in synovial fluids and tissues of patients with rheumatoid arthritis and osteoarthritis.

Inflammation normally results in enhanced synthesis and secretion of hypothalamic corticotropin-releasing hormone (CRH) which, in turn, exerts antiinflammatory effects by virtue of increased adrenal glucocorticoid production. CRH and CRH binding sites are also expressed in the peripheral nervous and immune systems. Our groups have recently shown that CRH is secreted locally in acute carrageenin-induced inflammation in rats and has predominantly proinflammatory effects. We have also shown that CRH is expressed in the joints of Lewis rats with experimental arthritis. To determine if CRH is present in human inflammatory arthritis, we examined synovial fluids and tissues from patients with rheumatoid arthritis (RA) or osteoarthritis (OA) and normal individuals. We found markedly enhanced expression of immunoreactive CRH in situ in synovium from patients, which was significantly greater in RA than in OA (p < 0.01). CRH concentrations were also significantly higher in RA (140 +/- 33 pg/ml, mean +/- SEM; n = 10) than OA (25 +/- 4 pg/ml; n = 6) synovial fluids (p < 0.005). HPLC showed immunoreactive CRH extracted from RA and OA synovial tissues and fluids coeluted with CRH 1-41. CRH mRNA was present in low levels in synovial tissue from patients with RA and, to a lesser extent, OA. In summary, immunoreactive CRH is locally secreted in the synovium of patients with RA and, at lower levels, OA. These data support the view that CRH functions as an autocrine and/or paracrine mediator of inflammation in humans.

Arthritis, Rheumatoid↗
PubMed1993

Increased calcium release from sarcoplasmic reticulum stimulated by inositol trisphosphate in spontaneously hypertensive rat heart cells.

It is known that inositol (1, 4, 5)-trisphosphate (IP3) stimulates Ca2+ release from sarcoplasmic reticulum (SR) in several tissues, but in cardiac myocytes this phenomenon has not been confirmed. The purpose of the present study was to confirm the effect of (1, 4, 5)-IP3 on Ca2+ release from SR in cardiac myocytes. The effect of IP3 on Ca2+ release from SR in hypertrophic cardiac cells was also determined. We examined the effects of IP3 on Ca2+ release from cardiac myocyte SR by the digital-image method in a single cell. We also determined the effect of IP3 on calcium release from isolated SR. SR was prepared from spontaneous hypertensive rat hearts and Wistar kyoto rat hearts. The SR was prelabeled with 45Ca2+, and then incubated with the indicated concentrations of IP3 for 1 min at 37 degrees C. In cardiac myocytes treated with saponin, Ca2+ release stimulated by 10 microM (1, 4, 5)-IP3 was detected by fura-2. In 45Ca2+ prelabeled SR, the maximal Ca2+ release was achieved at 10 microM IP3 incubated for 1 min. The release of Ca2+ was higher in SR of SHR than in the SR of WKY. IP3 stimulates Ca2-release from cardiac SR, and this release is greater in SHR than in WKY. However, it is uncertain whether this phenomenon plays a role in cardiac hypertrophy.

Animals↗
PubMed1993

Molecular characterization of rgp2, a gene encoding a small GTP-binding protein from rice.

We previously reported the isolation of rgp1, a gene from rice, which encodes a ras-related GTP-binding protein, and subsequently showed that the gene induces specific morphological changes in transgenic tobacco plants. Here, we report the isolation and characterization of an rgp1 homologue, rgp2, from rice. The deduced rgp2 protein sequence shows 53% identity with the rice rgp1 protein, but 63% identity with both the marine ray ora3 protein, which is closely associated with synaptic vesicles of neuronal tissue, and the mammalian rab11 protein. Conservation of particular amino acid sequence motifs places rgp2 in the rab/ypt subfamily, which has been implicated in vesicular transport. Northern blot analysis of rgp1 and rgp2 suggests that both genes show relatively high, but differential, levels of expression in leaves, stems and panicles, but low levels in roots. In addition, whereas rgp1 shows maximal expression at a particular stage of plantlet growth, rgp2 is constitutively expressed during the same period. Southern blot analysis suggests that, in addition to rgp1 and rgp2, several other homologues exist in rice and these may constitute a small multigene family.

Amino Acid Sequence↗
PubMed1993

Insulin responsiveness to glucose and tissue responsiveness to insulin during lactation in dairy cows.

The hyperglycemic clamp and hyperinsulinemic euglycemic clamp techniques were conducted to assess insulin responsiveness to glucose and tissue responsiveness to insulin in lactating and nonlactating Holstein cows. In the hyperglycemic clamp experiment, blood glucose concentrations were clamped at 50 mg/dl above the pre-infusion values by variable rates of glucose infusion. The mean plasma insulin increments over the baseline (insulin responsiveness to glucose) during hyperglycemia were lower (P < .05) in lactating cows than in nonlactating cows (23 vs. 102 microU/ml). In the hyperinsulinemic euglycemic clamp experiment, insulin was infused at the constant rate of 6.0 mU.kgBW-1.min-1 for 2 hr, and glucose was concomitantly infused at a variable rate to maintain the pre-infusion concentrations of blood glucose. Glucose infusion rates (tissue responsiveness to insulin) were similar (3.2 mg.kgBW-1.min-1) for lactating and nonlactating cows. It is concluded that insulin responsiveness to glucose is reduced, and tissue responsiveness to insulin remains unchanged during lactation in Holstein cows.

Animals↗
PubMed1993

Pancreatic insulin secretory response and insulin action in heat-exposed sheep given a concentrate or roughage diet.

The effects of heat exposure and type of diet on the insulin secretory response to glucose and glucose disposal in response to insulin action in female sheep were investigated employing hyperglycemic and euglycemic clamp techniques. Animals were divided into concentrate and roughage diet groups, and were maintained at the same intake levels of metabolizable energy and crude protein in both diets. Each diet group was subjected to either thermoneutral (20 degrees C, 70% RH) or hot (30 degrees C, 70% RH) environment, followed by glucose clamp experiments. Heat-exposed sheep showed significant increases in respiration rates (P < .001) and rectal temperature (P < .05). Plasma glucose concentrations in the basal conditions were lower (P < .01) in the hot environment than in the thermoneutral environment, but there was no significant difference in basal levels of plasma insulin between the environmental treatments. In the hyperglycemic clamp experiment, mean plasma insulin increments increased (P < .05) during the heat exposure period across diet treatments. The ratio of mean plasma insulin increment to glucose infusion rate tended to be higher (P < .07) in the hot environment than in the thermoneutral environment, but diet treatment did not affect the ratio of mean plasma insulin increment to glucose infusion rate. The euglycemic clamp technique showed that glucose infusion rates remained unchanged among treatments. Insulin secretion response to glucose could be stimulated in the hot environment.

Analysis of Variance↗
PubMed1993

Tobacco plants transformed with the O-acetylserine (thiol) lyase gene of wheat are resistant to toxic levels of hydrogen sulphide gas.

O-acetylserine (thiol) lyase (EC4.2.99.8) is the key enzyme in the cysteine biosynthetic pathway of plants and prokaryotes. The gene, cys1, encoding this enzyme was isolated from a wheat (Triticum aestivum L.) cDNA library, and its deduced amino acid sequence found to show 53% sequence identity with the O-acetyl-serine (thiol) lyase of Escherichia coli and Salmonella typhimurium. The deduced peptide consists of 325 amino acids (34.1 kDa), contains a conserved motif for the binding of pyridoxal phosphate, a co-factor required for enzymatic activity, and an N-terminal region of 37 amino acid residues resembling chloroplast transit peptides. The identity of cys1 was further demonstrated through complementation of an E. coli cysteine auxotroph, which lacks O-acetylserine (thiol) lyase, by expression of the wheat gene. Northern blot analysis showed that cys1 is highly expressed in green vegetative and reproductive tissues and in the roots of wheat, as well as in the leaves of several plant species. Southern blot analysis demonstrated that the gene exists as a single copy in the wheat genome. Tobacco plants transformed with cys1 in the sense orientation (sense plants) or antisense orientation (antisense plants), under the control of the CaMV 35S promoter, showed high levels of transcripts. The O-acetylserine (thiol) lyase activity in transgenic plants was determined, and found to be three- to fivefold higher in sense plants than in control plants, but unaffected in antisense transformants. Fumigation experiments with toxic levels of hydrogen sulphide (H2S) gas showed that while sense transformants were highly resistant, control and antisense plants were severely damaged by the treatment.

Amino Acid Sequence↗
PubMed1993

Human B-cell clones expressing lupus nephritis-associated anti-DNA idiotypes are preferentially expanded without somatic mutation.

Human monoclonal anti-single/double-stranded (ss/ds) DNA antibodies (NE-1 and NE-13) expressed cross-reactive idiotypes (Id), NE-1 Id, which have been detected on the lupus glomeruli-deposited anti-DNA antibodies. The nucleotide sequences of the variable regions of NE-1 and NE-13 clones were analogous except for one nucleotide difference in the Vk region. The VH and Vk gene segments of NE-13 clone were identical with germline genes VH4.21 and Vb (or Vb'), respectively. CDR3s of NE-1 and NE-13 heavy chains were arginine rich and CDR1s contained an amino acid stretch, SGYY, the inverted sequence of YYGS, which was shared among CDR3s of several anti-DNA antibodies. Clonal frequency analysis using a limiting dilution method revealed that NE-1 Id-positive clones at precursor cell level increased in lupus patients. These findings suggest that some IgM anti-DNA clones which express NE-1 Id associated with lupus nephritis use germline genes without mutation and they may be preferentially expanded at the precursor cell levels as well as at the mature cell level.

Adolescent↗