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Biomedical subjects

M Kikuchi

Publications and source records attributed to M Kikuchi.

At least 109 records · Page 6Linked to original sources
PubMed2001

A single-chain Fv fragment 2A3 specific for native lysozyme: isolation from a human synthetic phage display antibody library and characterization.

We have isolated from a human synthetic phage display library a clone, 2A3, which discriminates native lysozyme from denatured forms. Binding of single-chain Fv fragments (scFvs) of the clone to native hen egg white lysozyme was competitively inhibited by native hen egg white (hew) and human (h) lysozymes. Dot blotting analysis indicated that scFv of the clone did not react with denatured lysozymes. The K(d) values for scFv of 2A3 binding to native hew- and h-lysozymes were 3.78 x 10(-9) and 9.31 x 10(-9) M, respectively, indicating that 2A3 binds more strongly to native hew-lysozyme than to native h-lysozyme. The deduced amino acid sequence of the V(H) chain-CDR3 region of 2A3 was RRYALDY, of which the Arg residues at positions 1 and 2 of the CDR3 region were observed to be extremely rare in other antibodies by homology analysis. Based on these observations, site-directed mutagenesis of the RRYALDY-coding region was carried out. The results, combined with biomolecular analyses, demonstrated that Arg residues at positions 1 and 2 of this region were important for native lysozyme-binding.

Amino Acid Sequence↗
PubMed2001

Inhibition of experimental vasospasm by pretreatment with ultraviolet light irradiation in a rat femoral artery model.

OBJECTIVE: Chronic cerebral vasospasm is resistant to conventional treatments despite recent advances in treatment modalities. We studied the preventive effect of ultraviolet (UV) irradiation on development of vasospasm and its mechanism in a rat femoral artery model. METHODS: The rat femoral artery model for vasospasm was used in this investigation (n = 108). The femoral arteries were divided into four groups: empty and no irradiation (control), UV irradiation (UV group), blood placement (VS group), and blood placement after UV irradiation (VS + UV group). Luminal area was measured, and smooth muscle cell counts in the medial layer of the vessel wall were obtained. An immunohistochemical study was performed with cross sections of fixed femoral arteries at 12 hours and 1, 3, 5, 7, and 49 days after blood placement. The rings of femoral arteries on Day 7 were subjected to pharmacological study. RESULTS: Pretreatment with UV irradiation (VS + UV group) resulted not only in significant inhibition of chronic vasospasm but also in a significant decrease in smooth muscle cells compared with the VS group on Days 5 and 7. The UV-treated arteries (UV and VS + UV groups) exhibited a significant number of Bax- and Bcl-2-positive cells on Days 5 and 7, but few CPP-32 positive cells were observed at the same time points. In the pharmacological study, contractile response to KCI or phenylephrine was reduced significantly in the UV-treated arteries. CONCLUSION: These results imply that UV irradiation prevents chronic vasospasm and suggest that UV-induced cell death plays an important role in the preventive effect without causing complications during the chronic period.

Animals↗
PubMed2001

Determining the temperature distribution of a model vessel wall under pulsed laser irradiation: an experimental attempt to measure fibrous cap thickness and detect temperature elevation in atherosclerotic lesions.

In order to measure the temperature of atherosclerotic plaques, we developed a method to determine the temperature distribution of vessel walls using a three-layer phantom agar model. Under pulsed-laser irradiation, the thickness of upper layer corresponding to fibrous cap overlying the middle layer corresponding to atherosclerotic lesion could be calculated. The temperature was calculated from measured temperature changes under pulsed-laser irradiation.

Aorta↗
PubMed2001

Clonality assay of hematopoietic disorders: significance of the buccal epithelium as non-hematopoietic control and of 95% rejection limit as a novel criterion for monoclonality.

In clonality assays using X chromosome inactivation patterns (XCIPs), several factors such as constitutive and acquired XCIP skewing, lack of appropriate controls for hematopoietic diseases including multilineage disorders, and ambiguous criteria for monoclonality, have complicated determination of clonality. To address these issues, we studied the significance of the buccal epithelium as a non-hematopoietic control and the usefulness of the 95% rejection limit as a criterion for monoclonality. Sixty-nine females informative for human androgen receptor gene (HUMARA) were divided into "young," "middle-aged" and "elderly" groups. When XCIP correlation between the buccal epithelium, peripheral granulocytes, and peripheral lymphocytes was analyzed, the buccal epithelium showed a good correlation with granulocytes and lymphocytes in "young" and "middle-aged" groups, whereas the correlation was poor for the "elderly" group. For all age groups, there was an excellent correlation between granulocytes and lymphocytes. When we performed clonality assay for seven "young" and "middle-aged" patients with various leukemic phases using buccal epithelium as a non-hematopoietic control, all cases were accurately evaluated with the aid of a novel criterion, the 95% rejection limit. Our findings suggest that the buccal epithelium may constitute an effective control, especially when a non-hematopoietic control is required, and that the 95% rejection limit may serve as a statistically-defined criterion for monoclonality.

Adult↗
PubMed2001

Inhibitory effect of hyperglycemia on insulin-induced Akt/protein kinase B activation in skeletal muscle.

To determine the molecular mechanism underlying hyperglycemia-induced insulin resistance in skeletal muscles, postreceptor insulin-signaling events were assessed in skeletal muscles of neonatally streptozotocin-treated diabetic rats. In isolated soleus muscle of the diabetic rats, insulin-stimulated 2-deoxyglucose uptake, glucose oxidation, and lactate release were all significantly decreased compared with normal rats. Similarly, insulin-induced phosphorylation and activation of Akt/protein kinase B (PKB) and GLUT-4 translocation were severely impaired. However, the upstream signal, including phosphorylation of the insulin receptor (IR) and insulin receptor substrate (IRS)-1 and -2 and activity of phosphatidylinositol (PI) 3-kinase associated with IRS-1/2, was enhanced. The amelioration of hyperglycemia by T-1095, a Na(+)-glucose transporter inhibitor, normalized the reduced insulin sensitivity in the soleus muscle and the impaired insulin-stimulated Akt/PKB phosphorylation and activity. In addition, the enhanced PI 3-kinase activation and phosphorylation of IR and IRS-1 and -2 were reduced to normal levels. These results suggest that sustained hyperglycemia impairs the insulin-signaling steps between PI 3-kinase and Akt/PKB, and that impaired Akt/PKB activity underlies hyperglycemia-induced insulin resistance in skeletal muscle.

Animals↗
PubMed2001

Temperature measurement for energy-efficient ablation by thermal radiation with a microsecond time constant from the corneal surface during ArF excimer laser ablation.

Measurement of the temperature of the corneal surface during photorefractive keratectomy (PRK) is thought to be useful for monitoring the corneal ablation process, since the photothermal process has been proposed as the major mechanism of ArF excimer laser ablation. For temperature measurement, we measured thermal radiation from the corneal surface during ArF excimer laser ablation using a mercury-cadmium-telluride detector with a 1-micros time constant. To investigate the effects of temperature on ablation depth, the ablation depth of the cornea was measured by microscopy. When corneal ablation was initiated at the fluence of 65 mJ/cm2, the corneal surface temperature rose to 60-70 degrees C. The energy required for a unit-depth ablation (degrees C/microm) was lowest at 120 micro C. Monitoring of transient temperature during PRK provides important information on energy-efficient ablation, which may enable rapid and safe corneal incisions.

Animals↗
PubMed2001

Mapping energy metabolism in jaw and tongue muscles during chewing.

Investigators have used positron emission tomography with 18F-fluoro-D-deoxyglucose to obtain information not only for the diagnosis of cancers, but also for researching physiology in skeletal muscles. The aim of this study was to evaluate the activities of the jaw and tongue muscles during gum-chewing. Five volunteers aged 32-61 years were studied by positron emission tomography. They were requested to chew two pieces of chewing gum for 30 min after intravenous injection of 18F-fluoro-D-deoxyglucose. 18F-fluoro-D-deoxyglucose uptake in the intrinsic tongue muscle was significantly (p < 0.05) higher than that in the masseter, temporal, and medial pterygoid muscles. Heterogeneous uptake of 18F-fluoro-D-deoxyglucose was observed in the masticatory muscles. In addition, the tongue exhibited higher activity than the masticatory muscles. In conclusion, positron emission tomography with 18F-fluoro-D-deoxyglucose appeared to be a useful technique for investigating the physiologic activities of the skeletal muscles, which have been difficult to examine by conventional methods.

Adult↗
PubMed2001

Regulation of phosphoinositide metabolism, Akt phosphorylation, and glucose transport by PTEN (phosphatase and tensin homolog deleted on chromosome 10) in 3T3-L1 adipocytes.

To investigate the roles of PTEN (phosphatase and tensin homolog deleted on chromosome 10) in the regulation of 3-position phosphorylated phosphoinositide metabolism as well as insulin-induced Akt phosphorylation and glucose metabolism, wild-type PTEN and its phosphatase-dead mutant (C124S) with or without an N-terminal myristoylation tag were overexpressed in Sf-9 cells and 3T3-L1 adipocytes using baculovirus and adenovirus systems, respectively. When expressed in Sf-9 cells together with the p110alpha catalytic subunit of phosphoinositide 3-kinase, myristoylated PTEN markedly reduced the accumulations of both phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate induced by p110alpha. In contrast, overexpression of the C124S mutants apparently increased these accumulations. In 3T3-L1 adipocytes, insulin-induced accumulations of phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate were markedly suppressed by overexpression of wild-type PTEN with the N-terminal myristoylation tag, but not by that without the tag. On the contrary, the C124S mutants of PTEN enhanced insulin-induced accumulations of phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate. Interestingly, the phosphorylation level of Akt at Thr308 (Akt2 at Thr309), but not at Ser473 (Akt2 at Ser474), was revealed to correlate well with the accumulation of phosphatidylinositol 3,4,5-trisphosphate modified by overexpression of these PTEN proteins. Finally, insulin-induced increases in glucose transport activity were significantly inhibited by the overexpression of myristoylated wild-type PTEN, but were not enhanced by expression of the C124S mutant of PTEN. Therefore, in conclusion, 1) PTEN dephosphorylates both phosphatidylinositol 3,4-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate in vivo, and the C124S mutants interrupt endogenous PTEN activity in a dominant-negative manner. 2) The membrane targeting process of PTEN may be important for exerting its function. 3) Phosphorylations of Thr309 and Ser474 of Akt2 are regulated differently, and the former is regulated very sensitively by the function of PTEN. 4) The phosphorylation level of Ser474, but not that of Thr309, in Akt2 correlates well with insulin-stimulated glucose transport activity in 3T3-L1 adipocytes. 5) The activity of endogenous PTEN may not play a major role in the regulation of glucose transport activity in 3T3-L1 adipocytes.

3T3 Cells↗
PubMed2001

New sterols and triterpenoids from four edible mushrooms.

Four edible mushrooms, Panellus serotinus, Lepista nuda, Tricholoma matsutake and Naematoloma sublateritium, have been investigated chemically. Two new sterols, 5alpha,9alpha-epidioxy-(22E)-ergosta-7,22-diene-3beta,6alpha-diol (1) and 5alpha,9alpha-epidioxy-(22E)-ergosta-7,22-diene-3beta,6beta-diol (2), have been isolated from Panellus serotinus. Compound 2 was also isolated from Lepista nuda. A new sterol, 3beta,5alpha,9alpha,14beta-tetrahydroxy-(22E)-ergosta-7,22-dien-6-one (3), and compound 2 have been isolated from Tricholoma matsutake. Three new triterpenoids, sublateriols A-C (4-6), have been isolated from Naematoloma sublateritium. The structures of the new compounds were elucidated on the basis of their spectral data.

Agaricales↗
PubMed2001

Structures of new sesquiterpenoids from Farfarae Flos.

Two new bisabolane-type sesquiterpenoids, (3R,4R,6S)-3,4-epoxybisabola-7(14),10-dien-2-one and (1R,3R,4R,5S,6S)-1-acetoxy-8-angeloyloxy-3,4-epoxy-5-hydroxybisabola-7(14),10-dien-2-one, and a new oplopane-type sesquiterpenoid, 14(R)-hydroxy-7beta-isovaleroyloxyoplop-8(10)-en-2-one, were isolated from Farfarae Flos along with three known compounds. The structures of these compounds were elucidated on the basis of spectroscopic evidence.

Acetylation↗
PubMed2001

Studies on the constituents of Catalpa species. VI. Monoterpene glycosides from the fallen leaves of Catalpa ovata G. Don.

Five new monoterpene glycosides, ovatolactone 7-O-(6'-O-p-hydroxybenzoyl)-beta-D-glucopyranoside, ovatic acid methyl ester 7-O-(6'-O-p-hydroxybenzoyl)-beta-D-glucopyranoside, 7-O-p-hydroxybenzoylovatol 1-O-(6'-O-p-hydroxybenzoyl)-beta-D-glucopyranoside, 6'-O-p-hydroxybenzoylcatalposide and (2E,6R)-2,6-dimethyl-8-hydroxy-2-octenoic acid 8-O-[6'-O-(E)-p-coumaroyl]-beta-D-glucopyranoside were isolated from the fallen leaves of Catalpa ovata G. Don. Their structures were determined by extensive spectroscopic studies and syntheses.

Carbohydrate Conformation↗
PubMed2001

The formation of apical delta of the permanent teeth in dogs.

To determine the process of formation of apical delta, a histological study on the permanent teeth was carried out in dogs. A litter of 7 clinically healthy beagle dogs and 33 adult dogs (4- to 15- year-old) of 12 breeds with periodontal disease were used for the experiments. Teeth extracted from 6-,7-,8- and 9-month-old beagles were sectioned and stained with HE solution. Tooth roots obtained from adult dogs with periodontal disease were ground. Each tooth was classified into the following root types under a light microscope: Type I (no apical delta = no apical closure), II (few apical delta), IIIA (low apical delta) and IIIB (high apical delta). In the 6-month-old beagles, more than half the tooth roots were classified as type I. In the 7-month-old beagles, type IIIB apical delta was the most predominant and types I, II and IIIA apical delta were occassionally seen. Apical closure and delta were observed in all beagles at 8 months of age histologically. In the 8- and 9-month-old beagles, all root apexes observed were type IIIB. Most of the 314 tooth roots extracted from 33 adult dogs were type IIIB, but a few were type IIIA.

Animals↗
PubMed2001

Efficacy of enamel matrix proteins on apical periodontal regeneration after experimental apicoectomy in dogs.

Adult dogs have a complex apical delta structure in all root apexes of teeth. This complex structure may affect the formation of apical lesions in the teeth such as apical abscesses. The purpose of this study was to evaluate the efficacy of enamel matrix protein (EMP) which was used for periodontal regeneration therapy after an experimental apicoectomy for an assumed apical lesions of the teeth in dogs. The maxillar canine roots and maxillar fourth premolar buccal mesial roots in five beagles were experimentally apicoectomized under general inhalation anesthesia. After the root apex was exposed and excised, EMP was applied on the surface of the exposed dentin. After 12 weeks, dogs were euthanized. and the experimental teeth together with the surrounding soft and hard periodontal tissues were collected for histological evaluation under a light microscope. In the EMP group, the size of the defect where the root apex was removed was smaller than that of the control group. New cementum was dominantly achieved in the EMP group compared to the control group. Furthermore, new collagen fibers that bridged area between the new cementum and new alveolar bone were detected only in the EMP group. The present results demonstrated marked apical periodontal regeneration after apicoectomy in the EMP group. These results, therefore, suggest that the application of EMP can effectively induce the regeneration of periodontal strUctures in apicoectomized dogs.

Animals↗
PubMed2001

Usefulness of carperitide for the treatment of refractory heart failure due to severe acute myocardial infarction.

Carperitide (synthetic atrial natriuretic peptide) is a newly developed drug for the treatment of heart failure. Although this drug has been used for various types of heart failure, it remains unknown whether it has additive effects on hemodynamic parameters or renal excretory function during intensive treatment for acute refractory heart failure. We have examined the cardiorenal and hormonal effects of carperitide (0.05-0.10 microg / min / kg) in 9 patients (mean age: 67+/-8 years) with severe heart failure complicated with acute myocardial infarction, in which a range of intensive treatments have already been started. Hemodynamic parameters were determined before and 4, 24 and 48 hours after initiation of carperitide. Pulmonary capillary wedge pressure (mean+/-SD) had decreased dramatically from 21+/-6 to 11+/-5 mmHg (p<0.01) 4 hours after the treatment without significant renal effects. Heart rate and systemic blood pressure were not significantly changed. These beneficial effects were maintained for at least 24 hours. Plasma aldosterone levels fell significantly in response to the drug (from 148+/-68 to 56+/-29 pg / ml; p<0.05). However, mean hourly urine output remained unchanged after carperitide. In conclusion, intravenous infusion of carperitide promptly and persistently reduces left ventricular filling pressure without diuresis, hypotension, reflex tachycardia, or neurohormonal activation in patients with refractory heart failure due to severe acute myocardial infarction.

Aged↗
PubMed2001

Optimization of atrioventricular delay and follow-up in a patient with congestive heart failure and with bi-ventricular pacing.

Cardiac function is improved by bi-ventricular pacing in patients with severe reduced cardiac function. Atrioventricular (AV) delay optimization is also important in this therapy. However, the AV delay required to achieve the optimal AV synchrony varied from time to time. We have reported that the critical AV delay that induces diastolic mitral regurgitation (MR) may represent the upper limit of the optimal AV delay. The optimal AV delay can be predicted by a simple method; slightly prolonged AV delay-interval between the end of atrial kick and complete closure of the mitral valve (duration of diastolic MR) at the AV delay setting. [Case] 60 year old Japanese male with dilated cardiomyopathy. He was repeatedly admitted to our hospital due to congestive heart failure. Ejection fraction was 14%. ECG showed complete left bundle branch block and his PQ interval was 0.22 sec. He was dependent on intravenous injections of catecolamine and could not be discharged from the hospital for over one year. Optimal AV delay was predicted as 80 msec during bi-ventricular pacing by our formula. Cardiac output was 4.9, 6.0, 5.1 l/min when the AV delay was set at 50, 80, 110 msec. Cardiac function was improved from NYHA class III to II and he has been relieved from the dependency on intravenous catecholamine injections. AV delay was optimized (70-100 msec) by our method during follow-up for one year. This case indicates that AV delay optimization is important in bi-ventricular pacing.

Atrioventricular Node↗
PubMed2001

Insulin resistance with enhanced insulin signaling in high-salt diet-fed rats.

Previous clinical studies showed an apparent correlation between hypertension and insulin resistance, and patients with diabetes are known to have increased blood pressure responsiveness to salt loading. To investigate the effect of high salt intake on insulin sensitivity and the insulin signaling pathway, a high-salt diet (8% NaCl) or a normal diet was given to 7-week-old SD rats for 2 weeks. High salt-fed rats developed slightly but significantly higher systolic blood pressure than controls (133 +/- 2 vs. 117 +/- 2 mmHg, P < 0.001), with no change in food intake or body weight. High salt-fed rats were slightly hyperglycemic (108.5 +/- 2.8 vs. 97.8 +/- 2.5 mg/dl, P = 0.01) and slightly hyperinsulinemic (0.86 +/- 0.07 vs. 0.61 +/- 0.06 ng/ml, P = 0.026) in the fasting condition, as compared with controls. Hyperinsulinemic-euglycemic clamp study revealed a 52.7% decrease in the glucose infusion rate and a 196% increase in hepatic glucose production in high salt-fed rats, which also showed a 66.4% decrease in 2-deoxyglucose uptake into isolated skeletal muscle and a 44.5% decrease in insulin-induced glycogen synthase activation in liver, as compared with controls. Interestingly, despite the presence of insulin resistance, high salt-fed rats showed enhanced insulin-induced tyrosine phosphorylation of insulin receptor substrate (IRS)-1, IRS-2 (liver and muscle), and IRS-3 (liver only). Phosphatidylinositol (PI) 3-kinase activities associated with IRS and phosphotyrosine in the insulin-stimulated condition increased 2.1- to 4.1-fold, as compared with controls. Insulin-induced phosphorylation of Ser-473 of Akt and Ser-21 of glycogen synthase kinase-3 also increased 2.9- and 2-fold, respectively, in the liver of the high salt-fed rats. Therefore, in both the liver and muscle of high salt-fed rats, intracellular insulin signaling leading to PI 3-kinase activation is enhanced and insulin action is attenuated. The hyperinsulinemic-euglycemic clamp study showed that decreased insulin sensitivity induced with a high-salt diet was not reversed by administration of pioglitazone. The following can be concluded: 1) a high-salt diet may be a factor promoting insulin resistance, 2) the insulin-signaling step impaired by high salt intake is likely to be downstream from PI 3-kinase or Akt activation, and 3) this unique insulin resistance mechanism may contribute to the development of diabetes in patients with hypertension.

Animals↗
PubMed2001

Age-related changes in the testes of horses.

Atrophy of seminiferous tubules and interstitial fibrosis are frequently observed in aged horses. Samples from 8 male Thoroughbreds, age 4-24 years, were subjected to histological, electron microscopical and immunohistochemical examination and statistical analysis. There were statistically significant increases in collagen fibres in the lamina propria of seminiferous tubules and testicular interstitium in 3 horses age 23 and 24 years compared with 5 horses age 4-20 years (P<0.001). Lamina propria surrounding atrophic tubules was thickened by an increase in collagen type IV and elastic fibres and by proliferation of bizarre myoid cells. Basal lamina was also thickened but had decreased reactivity for collagen type IV. Some myoid cells changed morphologically to a swollen and irregular shape and contained abundant cytoplasmic organelles. Laser scanning microscopy revealed that cytoplasmic actin filaments were decreased; the remaining filaments were positive for alpha-smooth muscle actin and vimentin, and matrix metalloproteinase-2 was secreted. These myoid cells transformed into myofibroblasts. The changes are interpreted as evidence of injured structure and function of the lamina propria and basal lamina and may explain the functional decline of the blood-testis barrier. Myoid cells may play an important role in the progression of testicular fibrosis.

Actins↗