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Biomedical subjects

O Ito

Publications and source records attributed to O Ito.

At least 109 records · Page 6Linked to original sources
PubMed1994

Degradation of vasoactive intestinal polypeptide by rabbit gastric smooth muscle membranes.

Crude membrane fractions prepared from rabbit gastric fundic muscle degraded vasoactive intestinal polypeptide (VIP) with an average specific activity of 0.96 nmol/min/mg protein at 37 degrees C, pH 7.5, and at [S]o = 0.05 mM. The relative activities towards [Leu5]enkephalin, substance P, VIP, and neurotensin were approximately 7.7, 2.0, 1.0, and 0.54, respectively. The VIP degradation was inhibited by metal chelators EDTA and o-phenanthroline. CaCl2 at 0.3-1.0 mM enhanced VIP degradation up to twofold. Phosphoramidon, captopril, and bestatin, the specific inhibitors for endopeptidase-24.11, angiotensin-converting enzyme, and aminopeptidase M, respectively, did not affect VIP degradation significantly. However, the complex mixtures of VIP fragments generated implicates action of multiple peptidases including the aforementioned three peptidases and other unidentified peptidase(s).

Amino Acid Sequence↗
PubMed1994

Effects of washing with a neutralizing agent on alkaline skin injuries in an experimental model.

In this report a skin alkaline injury model was constructed using experimental rats and 2 N NaOH. We observed the effects of washing with a neutralizing agent on the subcutaneous tissue pH at 1, 10 and 30 min after injury and compared it with water-washing groups. In comparison with the water washing group, the peak pH values following the use of the neutralizing agent were significantly higher in the 1-min washing group, and significantly lower in the 10-min and 30-min washing groups. Changes in the pH values of the subcutaneous tissue after reaching a peak showed a similar course in the 1-min washing group, whereas in the 10 and 30 min washing groups there was a significantly different rate of decrease of pH. These results indicate that although treatment with a neutralizing agent directly after injury causes harmful effects due to the neutralizing reaction with a highly concentrated alkali. Subsequently with prolonged washing there is an effective reduction of the high pH.

Animals↗
PubMed1994

Comparative study of auricular dimensions for the normal auricles of microtia patients, their parents, and normal individuals.

We measured the dimensions of the normal auricle in microtia patients and those of both auricles in their parents, and compared the findings with data obtained in normal individuals. The physiognomical auricular length and width dimensions of the normal auricles in microtia patients were significantly smaller than those in normal individuals. The auricular length of the parents of microtia patients was also significantly smaller than in normal individuals. The auricles of the parents on the same side as those affected by microtia in the patients tended to be smaller than those on the contralateral side.

Adolescent↗
PubMed1994

Time limits for intestinal ischemia and congestion: an experimental study in rats.

We investigated to determine the time limits for intestinal ischemia and congestion. The experimental models were produced by clamping both ends and the intended feeder vessels of an approximately 1-cm length of rat jejunum. The results showed that in arteriovenous occlusion, the time required for the recovery rate to reach 50% was 7.03 hours. The time required for the recovery rate to reach 50% was 6.81 hours when arterial occlusion alone was performed and 3.70 hours when venous occlusion alone was performed. The difference between the two was statistically significant (p < 0.01). Consequently, it was found that the degree of intestinal damage due to venous occlusion was greater than the damage resulting from arteriovenous and arterial occlusion.

Animals↗
PubMed1994

Morphometric characteristics of cryptotia.

In this study, we measured the normal and affected auricles of patients with cryptotia by the Martin method, quantitatively analyzed the data, and conducted a comparative study. On the basis of auricular measurements, cryptotia is defined as a deformity of the upper one third of the auricle, which develops as a result of the sum total of vectors operating inferiorly and medially. Furthermore, these data showed that the deformity occurring along the vertical axis is greater and that the inferiorly directed vector is stronger than the medially directed vector. A helical adhesion-like deformity was observed in the normal side auricles of 3 patients with unilateral cryptotia, and the hypothesis that the upper portion of the auricle became embedded secondary to a deformity of the cartilage appeared to be valid.

Child↗
PubMed1994

Intestinal tissue pH monitoring in microsurgery: an experimental study in rats.

We monitored the pH of ischemic intestine in rats to determine whether such measurements were a useful method of postoperative monitoring. Measurement of intestinal pH was found to be useful in detecting vascular occlusion, in distinguishing arterial from venous occlusion, and in estimating the time of occlusion. This method of monitoring can be recommended after free intestinal grafting.

Animals↗
PubMed1994

Insulin stimulates NaCl transport in isolated perfused MTAL of Henle's loop of rabbit kidney.

To elucidate the mechanism of Na+ retention by insulin in vivo, the direct tubular effect of insulin on NaCl transport in the in vitro microperfused medullary thick ascending limb of Henle (MTAL) was examined. Insulin at 10(-6) mol/l in the bath increased transepithelial voltage (Vte) from 3.1 +/- 0.3 to 5.7 +/- 0.3 mV (n = 12, P < 0.0001). The effect of insulin on Vte was dependent on its concentration, and the half-maximal effect of insulin was observed at 5 x 10(-9) mol/l. Insulin at 10(-6) mol/l also caused a significant decrease of luminal Cl- concentration from 85.4 +/- 5.0 to 62.8 +/- 3.0 mmol/l (n = 5, P < 0.002) when the lumen was microperfused constantly at less than 1 nl/min. Insulin at 10(-6) mol/l also increased net lumen-to-bath Cl- flux (JCl) from 143 +/- 15 to 292 +/- 37 pmol.mm-1.min-1 (n = 5, P < 0.004). When the Na(+)-K(+)-adenosinetriphosphatase (Na(+)-K(+)-ATPase) in the basolateral membrane was blocked by 10(-4) mol/l ouabain, the insulin-mediated increase in Vte was completely suppressed. When the Na(+)-K(+)-2Cl- cotransporter in the luminal membrane of the MTAL was blocked by 10(-4) mol/l furosemide, the insulin-mediated increase in Vte was also abolished. To test whether adenosine 3',5'-cyclic monophosphate (cAMP) contributes to the action of insulin, we examined the effect of cAMP analogue and cAMP-dependent protein kinase inhibitor on the action of insulin. A maximal concentration (5 x 10(-4) mol/l) of dibutyryl-cAMP (DBcAMP) increased Vte and JCl.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorption↗
PubMed1994

Electrophysiological analysis of effect of propranolol in rabbit S2 proximal straight tubule.

The effect of dl-propranolol on the basolateral membrane potential (Vb) of in vitro microperfused S2 proximal straight tubules of the rabbit kidney was examined using conventional microelectrode techniques. In the steady-state condition, the average of 23 measurements of Vb was -44.8 +/- 2.0 mV. Addition of 10(-4) mol/l of dl-propranolol to the basolateral solution rapidly depolarized Vb by 12.1 +/- 1.3 mV in 20 sec (n = 15). The same dose of d-isomer of propranolol, which has no beta-blocking effect, also depolarized Vb to a similar extent. The non-selective beta-blocker nadolol, which possesses no membrane stabilising activity, had no effect on Vb. Depolarization of Vb by dl-propranolol in 20 seconds (propranolol-induced delta Vb) occurred in a dose-dependent manner. In the presence of 1 mmol/l Ba++ in basolateral solution, propranolol-induced delta Vb was strongly inhibited. The stilbene derivative DIDS at 1 mmol/l did not change propranolol-induced delta Vb, whereas the elimination of Cl- from the ambient conditions increased propranolol-induced delta Vb. The minimization of the luminal Na(+)-coupled organic solute transporter by collapsing of the lumen did not inhibit propranolol-induced delta Vb, indicating the lack of effect of propranolol on luminal Na(+)-coupled transporters. Ouabain at 10(-3) mmol/l in the bath did not eliminate propranolol-induced delta Vb, indicating the presence of a target transporter other than Na+/K+ ATPase for propranolol. These results suggest the following; 1) propranolol has a depolarizing effect on Vb in proximal tubule; 2) the effect of propranolol is independent of Cl- transport or Na(+)-coupled transporters in the luminal membrane; 3) propranolol depolarizes Vb by inhibiting the K+ channel in the basolateral membrane of S2 proximal tubule.

Animals↗
PubMed1994

Retreatment of chronic hepatitis C with interferon.

OBJECTIVE: We analyzed the retreatment of chronic hepatitis C with interferon to get the standpoint for the selection of patients to receive it. METHODS: A complete response was defined as continuous normalization of the serum alanine aminotransferase (ALT) level and continuous disappearance of serum hepatitis C virus RNA (HCV-RNA) during interferon administration and more than 6 months after. Patients without complete response were classified as noncomplete responders. From August 1990 to May 1993, we retreated 23 noncomplete responders on initial treatment with interferon and studied the factors that alter the effectiveness. RESULTS: Complete response was achieved in eight (34.8%) patients; the other 15 patients did not achieve this degree of response. Three patients were of genotype II and five were of genotype III in these eight complete responders. All complete responders were patients with relapse who had had normalized serum ALT levels during the initial administration and undetectable HCV-RNA at the end of the period. No patient who failed to achieve normalization of the serum ALT level on initial treatment achieved a complete response on retreatment. HCV-RNA concentrations before retreatment were significantly less than before initial treatment in the eight complete responders. CONCLUSION: Interferon retreatment of patients who do not achieve a complete response may be effective in relapsed cases with undetectable HCV-RNA at the end of initial treatment. Selection of patients to receive interferon retreatment requires careful review and consideration of genotype, HCV-RNA concentration, and the clinical response on initial treatment.

Alanine Transaminase↗
PubMed1993

Experimental study on alkaline skin injuries--periodic changes in subcutaneous tissue pH and the effects exerted by washing.

A skin alkaline injury model was constructed using rats and 2N-NaOH. The changes over time, paying special attention to subcutaneous tissue pH, were recorded and included a comparative study of the effect on subcutaneous tissue pH of washing with water at 1, 10 and 30 min after injury. After inflicting alkaline injury, the subcutaneous tissue pH reached its peak value at the 32nd minute and had not recovered to the pre-experimental level by the 90th minute. The peak pH values of the 1-, 10- and 30-min delays before washing groups were 7.97, 10.57 and 12.17, respectively. When washing was started within 1 min of injury the tissue pH values did not exceed 8.00. Washing had virtually no effect on lowering the raised pH levels when the delay between injury and the start of washing was 10 and 30 min.

Animals↗
PubMed1993

Experimental study of subcutaneously transferred intestine: effect of the presence of serous membrane on acceptance rate.

The serous membrane is considered suspect as one of the obstacles responsible for delaying the acceptance of free jejunal grafts. A model was created of subcutaneous transfer of jejunum from which the serous membrane had been experimentally removed and the authors compared acceptance rates for intestine with and without a serous membrane. Results showed acceptance rates of 0 percent, 37.5 percent, 87.5 percent, and 100 percent respectively, for intestine devoid of serous membrane in which the vascular pedicle had been ligated 4, 5, 7 and 14 days after transfer. When these findings were compared with the results of an experiment on intestine with an intact serous membrane, statistically significant differences were detected between the acceptance rates of the groups ligated 5 and 7 days after transfer. The acceptance time required for intestine devoid of serous membrane was shown to be shorter.

Abdomen↗
PubMed1993

Epidermal cell viability in rat skin preserved at 4 degrees C.

To determine the longest storage period for the clinical application of epidermal cells and a better method of preservation at 4 degrees C, we stored skin in various fluids and assessed the changes in epidermal cell viability. The time course of changes in the viability of epidermal cells from skin in various preservation fluids was similar to the results obtained with whole skin in previous studies. The best preservation fluid was found to be RPMI 1640 medium, and the best method of preservation was immersion in RPMI 1640 at 4 degrees C with a medium change every 3 days.

Animals↗
PubMed1993

Lack of direct action of atriopeptidase inhibitor on cellular pH regulation in rabbit S2 proximal straight tubules.

While the in vivo diuretic and antihypertensive effects of the newly-developed drug Candoxatril (UK-79300), a prodrug of a selective atriopeptidase inhibitor UK-73967 (API) are well established, the mechanism of its diuretic action is not yet fully understood due to the lack of information about its direct effects on proximal tubules. To elucidate whether this atriopeptidase inhibitor has any direct effects on proximal tubules, we examined the effect of API on intracellular pH (pHi) of the in vitro microperfused proximal S2 segment of rabbit kidney, using the pH-sensitive fluorescent dye, (2',7')-bis(carboxyethyl)-(5,6)-carboxyfluorescein (BCECF). In the steady-state condition, pHi was 7.13 +/- 0.02 (n = 19). Atriopeptidase inhibitor (API) at 100 microM added to the bath changed pHi by only 0.02 +/- 0.07 unit (n = 7, p > 0.05) in 10 min. The same concentration of API in the lumen changed pHi by 0.03 +/- 0.02 unit (n = 6, p > 0.05). To test whether the synergistic effects of API on the luminal and basolateral transport systems prevented the apparent change in pHi, we also examined the effect of API in the presence of amiloride in the lumen. The inhibition of Na+/H+ antiporter by the addition of 1 mM of amiloride to the lumen caused no change in pHi response to basolateral API application. API was without effect on pHi also in the presence of atrial natriuretic polypeptide (ANP). These results suggest that API per se has no significant effect on the process of proximal acidification over a short time period.

Animals↗
PubMed1992

An experimental study of ischemia following subcutaneous heterotopic intestinal graft: influence of arterial or venous occlusion.

A subcutaneously transferred intestinal model was prepared in the rat and experimental observations were conducted of serial histologic changes in the intestine and of acceptance rates, when the artery or vein in the pedicle was ligated at various times after transfer. Results showed 50 percent take in the artery-ligated group and 12.5 percent in the vein-ligated group, when performed 5 days after transfer; 87.5 percent take in the artery-ligated group and 50 percent in the vein-ligated group, when performed 7 days after transfer; and 100 percent take for both groups, when ligation was performed 14 days after transfer. Consequently, it was concluded that venous occlusion constitutes a greater danger to successful transfer of intestine than arterial occlusion.

Abdominal Muscles↗
PubMed1991

CO binding studies of engineered cytochrome P-450ds: effects of mutations at putative distal sites in the presence of polycyclic hydrocarbons.

The kinetic parameters of CO binding to genetically engineered cytochrome P-450d (P-450d) and two putative distal mutants, Glu318Asp and Thr322Ala, have been evaluated in the presence and absence of polycyclic hydrocarbons. The dissociation constant (Kd) of CO from wild-type P-450d was decreased by half (from 1.8 microM to approximately 0.9 microM) in the presence of phenanthrene or anthracene but was increased to 11 microM in the presence of 1,2:3,4-dibenzanthracene or 7,8-benzoflavone. These changed Kd values were not altered markedly by mutations at the putative distal site. In contrast, the recombination rate constants (kon) of CO to the Glu318Asp mutant in the presence of phenanthrene (15.5 X 10(5) M-1 s-1) and 7,8-benzoflavone (0.75 X 10(5) M-1 s-1) were much larger than those for the wild type. Similar but smaller increases of the kon values were observed for the Thr322Ala mutant. It was suggested that phenanthrene and anthracene distort the Fe-C-O bond and/or affect the access of CO to wild-type P-450d in an opposite way from 1,2:3,4-dibenzanthracene and 7,8-benzoflavone. Glu318 and Thr322 may be located so close to a CO binding channel in ferrous P-450d that mutations of these residues can open the sterically hindered CO channel caused by the hydrocarbons.

Animals↗
PubMed1991

Effects of chronic ozone exposure on growth, root respiration and nutrient uptake of rice plants.

To clarify the response of growth and root functions to low concentrations of ozone (O(3)), rice plants (Oryza sativa L.) were exposed to O(3) at 0.0 (control), 0.05 and 0.10 ppm for 8 weeks from vegetative to early heading stages. Exposure to 0.05 ppm O(3) tended to slightly stimulate the dry weight of whole plants up to 5 weeks and then slightly decrease the dry weight of whole plants. However, these effects were statistically significant only at 6 weeks. Exposure to 0.10 ppm O(3) reduced the dry weight of whole plants by 50% at 5 and 6 weeks, and thereafter the reduction of the dry weight of whole plants was gradually alleviated. Those changes in dry weight can be accounted for by a decrease or increase in the relative growth rate (RGR). The changes in the RGR caused by 0.05 and 0.10 ppm O(3) could be mainly attributed to the effect of O(3) on the net assimilation rate. Root/shoot ratio was lowered by both 0.05 and 0.10 ppm O(3) throughout the exposure period. The root/shoot ratio which had severely decreased at 0.10 ppm O(3) in the first half period of exposure (1-4 weeks) became close to the control in the latter part of exposure (5-8 weeks). Time-course changes in NH(4)-N root uptake rate were similar to those in the root/shoot ratio especially for 0.10 ppm O(3). On the other hand, root respiration increased from the middle to later periods. Since it is to be supposed that plants grown under stressed conditions change the ratio of plant organ weight to achieve balance between the proportion of shoots to roots in the plant and their activity for maintaining plant growth, these changes in root/shoot ratio and nitrogen uptake rate under long-term exposure can be considered to be an adaptive response to maintain rice growth under O(3) stress.

Journal Article↗
PubMed1991

4'-galactooligosaccharide affects sodium and potassium metabolism in rats.

The effect of different levels (0, 10 and 20%) of O-beta-D-galactopyranosyl-(1-4)-O-beta-D-galactopyranosyl-(1-4)-D- glucose (4'-GL) on the bioavailability of sodium and potassium was studied in 18 male rats. Three 3-d metabolic balance studies were conducted during the 62-d feeding trial. These were between d 30 and 32 (first period), 45 and 47 (second period) and 60 and 62 (third period). Growth and food intake were not significantly different (P less than 0.05) between the control group and the 4'-GL-fed groups. In rats fed 10 and 20% 4'-GL diet, the fecal sodium excretion was significantly greater (P less than 0.05) in all three balance periods. Fecal potassium excretion was significantly greater (P less than 0.05) in the 10% 4'-GL-fed group in the second balance period and the 20% 4'-GL-fed group in all balance periods relative to the control group. Although not statistically significant, rats in the 4'-GL-fed groups exhibited a tendency for lower sodium retention and higher potassium retention compared with the control group. The cecal weight of rats in both 4'-GL-fed groups was significantly heavier (P less than 0.05) than that of the control group at the end of study. Sodium concentration in the cecum was significantly lower (P less than 0.05) in the 20% 4'-GL-fed group relative to the other groups.

Animals↗