Biomedical subjects

K Ichihara

Publications and source records attributed to K Ichihara.

At least 73 records · Page 4Linked to original sources

PubMed1998

[Multivariate analysis of the associations between laboratory data and clinical features among patients with infectious mononucleosis syndrome].

Infectious mononucleosis (IM) syndrome is typically caused by EBV, but also by drugs and other organisms such as CMV and HBV. It demonstrates a wide range of clinical and laboratory characteristics, presumably depending on the age of onset. However, associations of laboratory abnormalities with the clinical features have not been well documented. We evaluated here, the associations among patients with IM syndrome using of multiple regression (MR) and multiple logistic regression (MLR) analyses. We examined 90 (40 males, 50 females) patients, who were admitted to our hospital with IM syndrome. The diagnostic criteria were fever and presence of atypical lymphocytes (> 5% of the WBC or the count including monocytes > 5000/microliter), and at least 3 of 7 clinical features: tonsillitis, lymphadenopathy, skin rash, hepato-, spleno-megaly, hepatic dysfunction. The diagnosis of EBV was serologically confirmed in 41 cases. MR revealed that the higher age group tended to have lower platelet counts, and that lower platelet counts were associated with higher ALT levels. In addition, MLR revealed that patients with skin rash tended not to have splenomegaly. The frequency of splenomegaly was not related to age, contrary to the findings of previous reports. These findings are useful to differentiate IM syndrome based on laboratory data.

Adolescent↗

PubMed1998

[Computer-assisted education of laboratory medicine based on common disease database and electric RCPC system using Internet technology].

We are developing computer-assisted instruction systems (CAI) for efficient education of laboratory medicine. To practice evidence-based laboratory medicine and put the education along the way, we gathered a large number of clinical records and constructed a database of clinical symptoms and signs of major diseases. We also constructed a web-based RCPC system featuring interactive multimedia materials and Q/A sessions to guide the students along important points in laboratory interpretations. We have been using these systems for 5th grade medical students and evaluated the effectiveness of them for the students to obtain knowledge regarding laboratory diagnosis. Although we still have a lot of aspects to improve, students showed interests in them and used them willingly. We believe that these CAI systems contribute to raise students' ability of problem solving in laboratory medicine.

Computer-Assisted Instruction↗

PubMed1997

Molecular cloning and expression of fatty acid alpha-hydroxylase from Sphingomonas paucimobilis.

Fatty acid alpha-hydroxylase (FAAH) catalyzes the initial reaction in alpha-oxidation of fatty acid to produce 2-hydroxy fatty acid. FAAH activity has been detected in a wide range of organisms from prokaryotes to eukaryotes. Here, we describe cloning of the FAAH gene from Sphingomonas paucimobilis, a sphingolipid- and 2-hydroxymyristic acid-rich bacterium. The isolated gene encoded 415 amino acids. A homology search revealed that amino acid sequences highly conserved in cytochrome P450 (P450) were present in FAAH. Although the heme-binding cysteine was recognizable at position 361, the consensus in the heme-binding region was modified by an insertion. Overall, FAAH has no significant identity to the known P450s. CO difference spectrum of recombinant FAAH showed the characteristic one of P450, except this peak was at 445 nm. These results suggest bacterial FAAH is a novel member of the P450 superfamily.

Amino Acid Sequence↗

PubMed1997

Purification and characterization of two new cytochrome P-450 related to CYP2C subfamily from rabbit small intestine microsomes.

Two forms of cytochrome P-450, designated P-450id and P-450ie, were purified to specific contents of 14.3 and 15.0 nmol of P-450/mg of protein, respectively, from small intestine mucosa microsomes of rabbits. P-450id and P-450ie showed apparent molecular weights of 50 and 49 kDa, respectively, on SDS-PAGE. Both P-450s catalyzed N-demethylation of nitrosodimethylamine. The NH2-terminal amino acid sequence (first 19 residues) of P-450id exhibited 74-90% identity with those of six members of the rabbit P-450 2C subfamily, except for P-450 2C3. Similarly, the NH2-terminal sequence (first 22 residues) of P-450ie showed 73-86% identity with those of the same members of the rabbit P-450 2C subfamily. The peptide mapping patterns of the two P-450s were quite different from each other. In addition, P-450id did not cross-react with the guinea-pig antibodies against P-450ie. The results indicate that rabbit small intestine mucosa contain two new distinct forms of P-450s, both of which may be classified into the 2C subfamily.

Amino Acid Sequence↗

PubMed1997

Purification and characterization of rabbit small intestinal cytochromes P450 belonging to CYP2J and CYP4A subfamilies.

A new form of P450 designated P450ib2 was purified from rabbit small intestine microsomes. This P450 had properties very similar, to P450ib (CYP2J1), and showed 88% identity with CYP2J1 in its first 20 NH2-terminal amino acid sequence, excluding 3 undetermined residues. Both P450ib and P450ib2 were immunohistochemically detected in the mucosal epitherial cells of the duodenum, jejunum, and ileum in the small intestine, whereas no immunoreactivity was observed in other tissues including liver, kidney, lung, colon, and stomach. The results support that the two closely related P450s are specifically localized in the rabbit small intestine. Another small intestinal P450, P450ia, was found to hydroxylate a wide variety of fatty acids including straight-chain, branched-chain, unsaturated, or hydroxy fatty acids, and prostaglandin A at the omega and (omega-1) positions. P450ia was identical with a rabbit kidney fatty acid omega-hydroxylase, CYP4A7, in its 25 NH2-terminal amino acid sequence, excluding 2 undetermined residues. The results identify P450ia as CYP4A7.

Amino Acid Sequence↗

PubMed1997

Serum protein standardization project in Japan: evaluation of an IFCC reference material (RPPHS/CRM470) and establishment of reference intervals.

Reference preparation for proteins in human serum (RPPHS), also called Certified Reference Material 470 (CRM 470), was prepared by the international Federation of Clinical Chemistry (IFCC) and is intended to serve as a new international plasma protein reference material. It is now being introduced into Japan. RPPHS possesses many excellent properties, including safety, stability, and accuracy in value assignment. Moreover, the physicochemical properties of its proteins are identical to those of fresh serum, giving it immunochemical behavior that is commutable with that of existing reference materials and calibrators in given immunoassays. Reference intervals of 13 serum proteins were determined for the first time using nephelometry and a new working calibrator assigned from RPPHS, which seems certain to play a critical role in the global standardization of specific protein immunoassays.

Age Factors↗

PubMed1997

Cell growth and differentiation of a novel mouse Ito (fat-storing) cell line transformed by a temperature-sensitive mutant of simian virus 40.

A novel mouse Ito (fat-storing) cell line (A640-IS) was established by transformation with a temperature-sensitive mutant of simian virus 40 (SV40) and the relationships between the expression of SV40 large T antigen and the growth, differentiation, and functions of A640-IS cells were investigated. A640-IS cells expressed large T antigen when cultured at 33 degrees C. At this temperature, the cells grew actively, assumed a fibroblastic shape, and showed few Ito cell characteristics. In contrast, when large T-antigen expression was inhibited by culture at 39 degrees C, the cells did not grow but differentiated into Ito cells as assessed by both morphological and functional characteristics. Expression of the transcription factor SCL (stem cell leukemia), which plays a role in the development and differentiation of blood cells, was observed at both 33 degrees C and 39 degrees C, although expression was greater at 33 degrees C. Therefore, opposite patterns of cell growth and the functions of differentiated cells occurred at 33 degrees C and 39 degrees C in this novel Ito cell line. Transforming growth factor beta1 stimulated A640-IS cells to produce fibronectin, collagen type III, and laminin. This unique Ito cell line provides a useful model to address important questions regarding the nature of these cells.

Adipocytes↗

PubMed1997

Multiple communicating intradural arachnoid cysts: usefulness of myelography and myelo-computed tomography using both lumbar and cervical punctures. Case report.

We report a case of multiple communicating intradural cystic lesions. Magnetic resonance imaging did not demonstrate the lesions. Neuroradiological diagnosis of the intradural arachnoid cysts was made from myelography and myelo-computed tomography using both lumbar and cervical punctures. These procedures give us useful information about flow dynamics in the spinal subarachnoid space.

Arachnoid Cysts↗

PubMed1997

Contribution of aranidipine metabolites with slow binding kinetics to the vasodilating activity of aranidipine.

Aranidipine, a novel dihydropyridine derivative, gives rise to two active metabolites, M-1(alpha) and M-1(beta), which exhibit hypotensive activity comparable to that of nifedipine. The aim of this study was to examine the recovery phase of the vasodilating effect of M-1(alpha) and of M-1(beta), to determine their binding characteristics and to compare the results with those for aranidipine and other dihydropyridine derivatives. During intra-arterial infusion into the femoral vascular beds of anesthetized dogs, M-1(alpha), M-1(beta), and nifedipine, produced increases in femoral blood flow at doses three times higher than the dose of aranidipine required to produce a comparable effect. The onset and recovery of the effects of the metabolites on femoral blood flow were significantly slower than the onset and recovery of the effect of nifedipine. The inhibitory activities of M-1(alpha) and M-1(beta) towards stimulated 45Ca uptake in isolated guinea pig aorta were less than that of aranidipine. In binding studies, using porcine heart membrane preparations, [3H]M-1(alpha) and [3H]M-1(beta) had larger Kd values than [3H]aranidipine and [3H]nitrendipine, but the maximal binding number for each of them was almost the same. The association and dissociation rate constants for [3H]M-1(alpha) and [3H]M-1(beta) binding, as well as those for [3H]aranidipine binding, were significantly smaller than those for [3H]nitrendipine, corresponding to the recovery of the in vivo vasodilating effects of the metabolites. The dissociation rate constants of these radiolabeled ligands were highly positively correlated with the elimination rate constants of their in vivo vasodilating effects. From these results, we conclude that M-1(alpha) and M-1(beta), although their binding affinities and Ca2+ antagonistic actions are less potent, possess slower kinetic binding properties than many other dihydropyridines and that the slow kinetic interaction of these metabolites with the dihydropyridine receptor may contribute to the long-lasting in vivo vasodilating effect of aranidipine.

Animals↗

PubMed1997

Limitation of stunning in dog myocardium by nucleoside and nucleotide mixture, OG-VI.

OG-VI is a solution composed of 30 mM inosine, 30 mM sodium 5'-guanylate, 30 mM cytidine, 22.5 mM uridine, and 7.5 mM thymidine, expecting to use for total parenteral nutrition. We examined the effect of OG-VI on myocardial contractile dysfunction during reperfusion after ischemia (myocardial stunning) in dogs. Pentobarbital-anesthetized dogs were subjected to 20-min left anterior descending coronary artery ligation followed by 30-min reperfusion. Saline, OG-VI or its constituents [inosine and sodium 5'-guanylate mixture (IG), and cytidine, uridine, and thymidine mixture (CUT)], or 5-amino-4-imidazole carboxamide riboside (AICAr) was infused at 0.1 mL.kg-1.min-1, starting 30 min before the ischemia. The contractile function was determined by ultrasonometry and assessed as % segment shortening (%SS). %SS was markedly decreased by ischemia, and returned toward pre-ischemic level after reperfusion, although the recovery was incomplete. The %SS was almost completely recovered by OG-VI and IG, and to a lesser extent by AICAr; CUT was ineffective. In the presence of 1 mg.kg-1 of 8-cyclopentyl-1,3-dipropylxanthine (DPCPX, a selective adenosine A1 receptor antagonist), cardioprotective effect of OG-VI on stunned myocardium was still observed. In conclusion, infusion of OG-VI improved myocardial contractile dysfunction in stunned myocardium. This effect was more potent than its constituents and AICAr. Adenosine A1 receptors are not involved in the mechanism.

Adenosine Triphosphate↗

PubMed1997

Purification and characterization of glutaredoxin (thioltransferase) from rice (Oryza sativa L.).

We purified and characterized glutaredoxin (thioltransferase), which catalyzes thiol/disulfide exchange reaction, for the first time in plants. The purification procedure employed an immunoabsorbent, antiglutaredoxin-Sepharose. Glutaredoxin was purified about 2,200-fold from rice bran and it appeared to be homogeneous on SDS-PAGE. MALDI-TOF mass spectrometry revealed that the protein has a molecular mass of 11,097.9 Da. Rice glutaredoxin consists of 105 amino acid residues, containing the tetrapeptide -Cys-Phe-Pro (Tyr)-Cys-, which constitutes the active site of Escherichia coli and mammalian glutaredoxins. Inactivation assay also indicated that cysteine residues are responsible for enzyme activity. Kinetic analyses revealed that the enzyme did not exhibit normal Michaelis-Menten kinetics. The enzyme has an optimum pH of about 8.7 with 2-hydroxyethyl disulfide as a substrate. In addition, rice glutaredoxin has dehydroascorbate reductase activity, like mammalian glutaredoxin.

Amino Acid Sequence↗

PubMed1997

Effects of aranidipine, a novel calcium channel blocker, on mechanical responses of the isolated rat portal vein: comparison with typical calcium channel blockers and potassium channel openers.

We investigated the effects of aranidipine, a dihydropyridine-type Ca2+ channel blocker, on contractile responses to KCl and spontaneous contractions in isolated rat portal veins in comparison with those of the Ca2+ channel blockers, nifedipine, nicardipine, nitrendipine, diltiazem, and verapamil, and of the K+ channel openers, cromakalim and nicorandil. All the Ca2+ channel blockers concentration-dependently inhibited contractions induced by KCl. Interestingly, aranidipine was more potent against the low K+ (20 mM)-induced contraction than the high K+ (80 mM)-induced contraction, whereas the other Ca2+ channel blockers were equally potent against contractions induced by either concentration of KCl. Cromakalim and nicorandil were effective only on the low K(+)-induced contraction. In addition, all the Ca2+ channel blockers and the K+ channel openers tested inhibited the amplitude of spontaneous contractions of isolated rat portal vein. Tetraethylammonium (TEA), a classic K+ channel blocker, significantly attenuated the effect of aranidipine but not of other Ca2+ channel blockers on the spontaneous contractions. The cromakalim-induced inhibition of spontaneous contractions was antagonized by TEA. Thus aranidipine was found to be different from the typical Ca2+ channel blockers and in part similar to the K+ channel openers in inhibiting mechanical responses of isolated rat portal vein, suggesting that activation of K+ channels may in part in part be involved in the aranidipine-induced vasodilation.

Animals↗

PubMed1997

Effects of OG-VI, a nucleoside-nucleotide mixture, on ischemic myocardial metabolism in dogs.

BACKGROUND: OG-VI is a solution composed of 30 mmol/l inosine, 30 mmol/l sodium 5'-guanylate, 30 mmol/l cytidine, 22.5 mmol/l uridine, and 7.5 mmol/l thymidine, which is known to improve myocardial stunning. OBJECTIVE: To study the effect of OG-VI on myocardial energy and carbohydrate metabolism during ischemia. METHODS: Ischemia was induced in pentobarbital-anesthetized open-chested dogs for 3 min by left anterior descending coronary artery ligation. Saline, 1.2 mmol/kg per min OG-VI, or 12 mmol/kg per min OG-VI was infused at 0.1 ml/kg per min, starting 30 min before the onset of ischemia. The myocardium was extracted 3 min after the onset of ischemia, and used to determine the tissue levels of energy and carbohydrate metabolites. RESULTS: Ischemia decreased the levels of ATP and fructose 1,6 diphosphate significantly, and increased those of AMP, glucose 6 phosphate, fructose 6 phosphate and lactate. OG-VI infusion preserved the adenine nucleotide levels significantly in 3 min ischemic hearts, and attenuated the ischemia-induced alteration of carbohydrate metabolism. CONCLUSION: OG-VI may improve the myocardial metabolic derangement induced by ischemia.

Animals↗

PubMed1997

Effect of efonidipine, a novel dihydropyridine derivative, on myocardial metabolic changes induced by coronary artery ligation in dogs: comparison with nifedipine.

Efonidipine is a dihydropyridine derivative having a vasodilating action, which is slower in onset and longer in duration than that of nifedipine. In the present study, we compared the effects of efonidipine with those of nifedipine on the ischemic myocardial metabolism in anesthetized dogs. The heart was made ischemic by ligating the left anterior descending coronary artery (LAD) completely for 3 or 30 min. Efonidipine or nifedipine was injected intravenously, 10 or 3 min, respectively, before the start of LAD occlusion. Efonidipine (0.01 or 0.03 mg/kg) decreased both blood pressure and heart rate, whereas nifedipine (0.003 mg/kg) decreased blood pressure and increased heart rate. The magnitude of decrease in mean blood pressure induced by 0.03 mg/kg efonidipine was similar to that induced by 0.003 mg/kg nifedipine. Although efonidipine did not modify the changes in myocardial carbohydrate metabolism induced by ischemia, it attenuated the ischemia-induced decrease in the myocardial level of adenosine triphosphate and energy charge potential. Nifedipine, however, did not modify the changes in both myocardial energy and carbohydrate metabolism induced by ischemia. The results suggest that efonidipine has a cardioprotective effect in the dog, probably because of its negative chronotropic effect.

Animals↗

PubMed1997

Protective effect of amiloride against reperfusion damage as evidenced by inhibition of accumulation of free fatty acids in working rat hearts.

To examine whether amiloride protects against ischemia-induced or reperfusion-induced damage to the heart, mechanical and metabolic studies were performed in the isolated, working rat heart. Ischemia decreased both mechanical function and the tissue levels of high-energy phosphates and increased the tissue levels of free fatty acids (FFAs). Reperfusion restored the levels of high-energy phosphates but further increased FFA accumulation. For this reason, accumulation of FFAs was used as an indicator of both ischemia-induced and reperfusion-induced damage. Drugs were added to the perfusion solution 5 min before ischemia until the end of ischemia (pre) or until 10 min after reperfusion (pre + post). Diltiazem (1 or 5 mumol/L pre) decreased the mechanical function of the non-ischemic heart and attenuated both ischemia-induced and reperfusion-induced accumulation of FFAs. Amiloride (50 mumol/L pre) did not affect the mechanical function of the non-ischemic heart or attenuate ischemia-induced or reperfusion-induced FFA accumulation effectively. However, amiloride (50 mumol/L pre + post) did markedly attenuate the reperfusion-induced accumulation of FFAs. In conclusion, diltiazem attenuates both ischemia-induced and reperfusion-induced myocardial damage, probably through its energy-sparing effect as a result of a decrease in mechanical function before ischemia. In contrast, amiloride attenuates only the reperfusion-induced myocardial damage through mechanisms other than the energy-sparing effect.

Amiloride↗

PubMed1997

Inhibitory effects of glibenclamide and pertussis toxin on the attenuation of ischemia-induced myocardial acidosis following ischemic preconditioning in dogs.

Ischemic preconditioning is known to be mediated by several humoral factors, such as adenosine, norepinephrine, and bradykinin. We examined intracellular signal transduction of ischemic preconditioning following receptor stimulation. Alterations in the pH of the ischemic bed were monitored to assess the response of control and ischemic-preconditioned myocardium to glibenclamide and pertussis toxin. Pentobarbital-anesthetized open-chest dogs were subjected to 40 min of ligation of the left anterior descending coronary artery. Ischemic preconditioning was elicited by 25-min periods of coronary ligation followed by 5 min of reperfusion before a 40-min period of ligation. Glibenclamide (0.3 mg/kg)was given i.v. 20 min before the onset of ischemic preconditioning. Pertussis toxin (6-10 micrograms/kg) was given i.v. 3 days before the experiment. Tissue myocardial pH was measured by a glass micro-pH electrode. Ischemia for 5 min decreased myocardial pH and reperfusion returned it to the preischemic levels. Ischemia for 40 min decreased the myocardial pH from 7.43 +/- 0.06 to 6.43 +/- 0.08. Ischemic preconditioning significantly attenuated the decrease in myocardial pH (6.57 +/- 0.06) induced by 40 min of ischemia. Pretreatment with either glibenclamide or pertussis toxin completely abolished the effect of ischemic preconditioning on ischemic myocardial acidosis. Ischemic preconditioning can attenuate ischemia-induced myocardial acidosis in dogs, and this effect is mediated by activation of adenosine triphosphate-sensitive potassium channels and pertussis toxin-sensitive guanosine triphosphate-binding protein.

Acetylcholine↗

PubMed1997

Cardioprotective effect of K-7259, a novel dilazep derivative, against ischemia-reperfusion damage in isolated, working rat hearts.

Global ischemia (15 min) followed by reperfusion (10, 20 or 30 min) was performed in isolated, working rat hearts. Ischemia depressed mechanical function, which was not restored by reperfusion of 20 min. Preischemic administration of K-7259 (N,N'-bis[4-(3,4,5-trimethoxyphenyl)butyl]homopiperazine dihydrochloride) (1, 5 or 10 microM) decreased the function before ischemia, but it attenuated the ischemia-induced dysfunction during reperfusion (20 min). Postischemic administration of K-7259 (10 microM) or dilazep (20 microM) also attenuated the ischemia-induced dysfunction during reperfusion (30 min). Ischemia-reperfusion (10 min) increased the tissue malondialdehyde level, and postischemic administration of K-7259 (10 microM) or dilazep (20 microM) attenuated the malondialdehyde accumulation. K-7259 has a cardioprotective effect when given either before or after ischemia.

Animals↗

PubMed1997

Lipid peroxidation in the pancreas and other organs in streptozotocin diabetic rats.

We studied the relationship between changes in lipid peroxides and those in catalase activity in pancreases, livers and hearts of streptozotocin-induced diabetic rats. Animals were killed 2 or 7 weeks after saline or streptozotocin (32 mg/kg, i.v.) injection. The levels of blood glucose and plasma insulin in the 2-week streptozotocin-treated rats were 176.8+/-20.5 mg/dl and 29.9+/-3.2 microU/ml, respectively. In the pancreas, the lipid peroxide level significantly decreased and the catalase activity significantly increased 2 weeks after streptozotocin injection. These changes recovered after 7 weeks. In the heart, the lipid peroxide level significantly increased without any change of catalase activity 2 weeks after the initiation of diabetes. After 7 weeks, the catalase activity significantly increased and the lipid peroxide level returned to the control level. In the liver, there was no change in the lipid peroxides and catalase in the 2-week streptozotocin-treated rats, whereas the catalase activity significantly increased 7 weeks after the injection. It was suggested that the defense system in the pancreas to oxidative stress may be evoked in an early stage of streptozotocin-induced diabetes.

Animals↗