Biomedical subjects

Y Tsukahara

Publications and source records attributed to Y Tsukahara.

At least 19 recordsLinked to original sources

PubMed2006

Different transitions of multifocal electroretinogram recordings between patients with age-related macular degeneration and polypoidal choroidal vasculopathy after photodynamic therapy.

AIM: To compare and evaluate the transitions in retinal function after photodynamic therapy (PDT) between age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) using multifocal electroretinograms (mfERGs). METHODS: 10 eyes with choroidal neovascularisation (CNV) secondary to AMD and 11 eyes with CNV secondary to PCV were included in the study. mfERGs were recorded before PDT, and 1 week and 3 months after PDT. mfERG recordings were acquired by a Veris system (V.3.1.3) using a 103 hexagon stimulus. The first-order kernel was used to calculate amplitudes and latencies. Mean amplitudes and latencies from two central rings rated 0-4 degrees of visual angle were analysed and compared with each disease. RESULTS: In AMD, the mean first negative peak (N1) amplitudes tended to decrease, and the mean first positive peak (N1P1) amplitudes reduced to significant levels (p = 0.047) 1 week after PDT. 3 months after PDT, there were no significant differences in the mean N1 and N1P1 amplitudes compared with pre-PDT values. In PCV, there were no significant changes in the mean N1 and N1P1 amplitudes 1 week after treatment. However, 3 months after PDT, mean amplitudes showed significant increases in N1 (p = 0.008) and N1P1 (p = 0.006) amplitudes compared with pre-PDT values. CONCLUSIONS: mfERG recording transitions are different between patients with AMD and those with PCV. In patients with AMD, these results may show transient impairments in retinal function 1 week after PDT, but in those with PCV, the efficacy of PDT is superior to the impairment after PDT.

Aged↗

PubMed2003

Umbilical plasma kininase I activity in fetal hypoxia.

To shed light on the role of bradykinin in preeclampsia in addition to acute hypoxia, we measured the activity of kininase I, the enzyme responsible for its degradation, in umbilical plasma. Kininase I activity in umbilical arteries was compared with that in the umbilical veins. The relationship between kininase I and pH values was also evaluated in women with and without preeclampsia. Also, enzyme activity in supernatants of fetal hepatic cells (NFL/T) cultured under hypoxic or normoxic conditions were determined. Kininase I activity levels in fetal umbilical arteries and veins (n = 33) were similar (r = 0.77). Hypoxia caused suppression of kininase I activity in the supernatant cultures of NFL/T after one hour. However, after 8 and 24 hours, kininase I activity was significantly greater than under normoxic conditions (p < 0.05). Kininase I activity of fetal umbilical vein significantly decreased in the presence of acidemia in the uncomplicated group (n = 75, r = 0.42), whereas the activity negatively correlated with umbilical arterial pH in the preeclamptic group (n = 10, r = - 0.65). Kininase I activity levels in cases complicated with preeclampsia were significantly higher than without preeclampsia (49.2 +/- 9.1 vs. 66.2 +/- 11.3 nmol/ml/min). The present study indicates that kininase I acts as a regulatory factor in bradykinin degradation.

Bradykinin↗

PubMed2001

Distribution of blue-sensitive photoreceptors in amphibian retinas.

Previously, we reported that an opsin (Rc-MS) belonging to the SWS2 group opsins is expressed in bullfrog green rods [Hisatomi, O. et al., FEBS Lett., 1999, 447, 44-48]. An anti-Rc-MS antiserum recognized the cones of the Japanese common newt, Cynops pyrrhogaster, which has no green rods. We isolated a cDNA encoding an SWS2 group opsin (Cp-SWS2) from this newt and found that Cp-SWS2 is expressed in a small population of the cones. Our results suggest that SWS2 opsins can be expressed in either green rods or cones of caudata. It seems reasonable to suppose that green rods arose before amphibia were divided into caudata and anura.

Amino Acid Sequence↗

PubMed2001

Monte Carlo simulation of growth of porous SiOx by vapor deposition.

A random network model containing defects has been developed and applied to the deposition of amorphous SiOx films on a flat substrate. A new Monte Carlo procedure enables dangling bonds to migrate and annihilate. The degree of porosity in the films is found to increase with oxygen content. As the oxygen content increases a larger fraction of pore surfaces is covered with oxygen, and the density of dangling bonds on pore surfaces decreases. Oxygen plays the role of a surfactant, lowering the energies of pore surfaces and enhancing the porosity of amorphous SiO2 compared to amorphous Si.

Journal Article↗

PubMed2001

Mutation screening of the hepatocyte nuclear factor (HNF)-6 gene in Japanese subjects with diabetes mellitus.

Heterozygous mutations in the genes encoding transcription factors (HNF-1alpha, HNF-1beta and HNF-4alpha) in the hepatocyte nuclear factor (HNF) network are associated with maturity-onset diabetes of the young (MODY). We screened HNF-6 gene for mutations in 34 Japanese subjects with MODY/early-onset diabetes mellitus and 56 subjects with late-onset diabetes mellitus. One single nucleotide polymorphism (SNP) at codon 287 (GGG to GGT) was found in the gene and the frequency was similar among MODY/early-onset diabetes, late-onset diabetes and control subjects. Genetic variations in the HNF-6 gene are not likely to contribute to the susceptibility to diabetes mellitus in Japanese.

Adolescent↗

PubMed2001

iNOS expression by activated neutrophils from patients with sepsis.

BACKGROUND: Enhanced production of nitric oxide (NO) is associated with various inflammatory diseases such as sepsis. Although activated neutrophils are presumably involved in septic organ injury, the expression of inducible nitric oxide synthase (iNOS) by these cells has not been elucidated. The authors investigated whether activated neutrophils in sepsis could induce mRNA for iNOS and produce NO. METHODS: Peripheral blood neutrophils were obtained from healthy volunteers, and septic patients underwent a surgical operation. The neutrophils of the healthy volunteers were stimulated with lipopolysaccharide (LPS) and/or tumour necrosis factor-alpha (TNF-alpha). The iNOS expression and NO production were examined by the reverse transcription-polymerase chain reaction and Griess method, respectively. RESULTS: Circulating neutrophils obtained from patients with sepsis expressed higher levels of iNOS mRNA than those from patients with systemic inflammatory response syndrome (SIRS). Resting neutrophils from normal controls did not express iNOS mRNA and thus did not produce NO. After in vitro stimulation with LPS and TNF-alpha, the neutrophils did express iNOS mRNA and thus produce NO. CONCLUSION: Activated neutrophils may be one source of NO production in sepsis.

Adult↗

PubMed2001

Prenatal diagnosis of congenital diaphragmatic eventration by magnetic resonance imaging.

Diaphragmatic eventration is a rare abnormality, which has the similar ultrasonographic features to congenital diaphragmatic hernia. Therefore, these two diseases are difficult to differentiate from each other prenatally. We present here a case in which the presence of congenital diaphragmatic eventration was strongly suggested by magnetic resonance imaging (MRI) and ultrasonography. A 26-year-old pregnancy woman, gravida 0, para 0, week 35, was admitted to our hospital with an ultrasonographic abnormality of the fetal thorax. MRI and ultrasonography showed interesting features which strongly suggested the presence of congenital diaphragmatic eventration and helped to differentiate it from congenital diaphragmatic hernia.

Adult↗

PubMed2001

The process of cell adhesion among dissociated single cells of Hydra: morphological observations.

Ultrastructural observations were made on the initial adhesion process at the adherent region of Hydra endodermal cell pairs brought into contact (following dissociation) using a three-dimensional laser manipulator. Total contact length across the diameter of the adherent region decreased during the period 10-60 min after initial adhesion. However, the mean numbers of closest (<4 nm) and medium (5-25 nm) separation distances between membranes (thought to be important in total cell adhesion) were not significantly different. These data indicate that adherent cell pairs maintain a constant adhesiveness during the first 60 min of the adhesion process, despite membrane rearrangements. The relative length of each separation distance in adherent cell pairs approached that reported previously for intact Hydra. The sums of lengths in both the closest and medium categories (as a proportion of total contact length) increased because the length of cleavages (distances >25 nm) decreased significantly during the same time period. These results suggest that adherent cell pairs undergo rapid, active membrane changes in the adherent region, which might be associated with cell sorting. The possible significance of these changes for active rearrangement are discussed.

Animals↗

PubMed2001

Diurnal changes in retinula cell sensitivities and receptive fields (two-dimensional angular sensitivity functions) in the apposition eyes of Ligia exotica (Crustacea, Isopoda).

The structural organization of the retinula cells in the eye of Ligia exotica changes diurnally. At night, the microvilli elongate, losing the regular and parallel alignment characteristic of the day condition. Crystalline cones and distal rhabdom tips are not pushed into each other during the day, but at night the rhabdoms protrude into the crystalline cones by up to 5 microm. Screening pigment granules in the retinula cells disperse during the night, but migrate radially towards the vicinity of the rhabdom during the day. No such displacements of the pigment granules of either distal or proximal screening pigment cells were observed. The sensitivity of the eye, monitored by electroretinogram (ERG) recordings, changes diurnally: values at midnight are, on average, 10 times those occurring during the day. However, intracellular recordings from single retinula cells (50 during the day and 50 at night) indicate that the difference between night and day sensitivities is only 2.5-fold. Two-dimensional angular sensitivity curves, indicative of a single unit's spatial sensitivity, had considerably less regular outlines at night than during the day. If based on the 50 % sensitivity level, day and night eyes possessed receptive fields of almost identical width (approximately 2 degrees), but if sensitivities below the 50 % limit were included, then receptive fields at night were significantly more extensive. We suggest that the morphological adaptations and diurnal changes in chromophore content seen in the apposition eye of L. exotica allow this animal to improve its photon capture at night while preserving at least some of the spatial resolving power characteristic of the light-adapted state. This would explain why this animal is capable of performing complex escape behaviours in the presence of predators both in bright and in very dim light.

Animals↗

PubMed2001

Inositol-1,4,5-trisphosphate-binding proteins controlling the phototransduction cascade of invertebrate visual cells.

The main phototransduction cascade in invertebrate visual cells involves the turnover of phosphatidylinositol, an important biochemical mechanism common to many signal-transduction systems. Light-activated rhodopsin stimulates guanine nucleotide exchange on the Gq class of G-protein, which activates phospholipase C to hydrolyze phosphatidylinositol 4,5-bisphosphate to inositol-1,4,5-trisphosphate and diacylglycerol. Subsequently, inositol-1,4,5-trisphosphate-binding proteins continue the signal cascade. Here, we report on the first inositol-1,4,5-trisphosphate-binding proteins demonstrated in an invertebrate visual system with our investigation of the photosensitive rhabdoms of squid. We screened the ability of proteins to interact with inositol-1,4,5-trisphosphate by affinity column chromatography with an inositol-1,4,5-trisphosphate analogue. We detected an inositol-1,4,5-trisphosphate-binding affinity in phospholipase C, receptor kinase and five other proteins in the cytosolic fraction and, surprisingly, rhodopsin in the membrane fraction. A binding assay with (3)H-labelled inositol-1,4,5-trisphosphate demonstrated the inositol-1,4,5-trisphosphate affinity of each of the purified proteins. Since rhodopsin, receptor kinase and phospholipase C are involved upstream of phosphatidylinositol turnover in the signal cascade, our result suggests that phosphatidylinositol turnover is important in feedback pathways in the signalling system.

Animals↗

PubMed2001

Stereoselective pharmacokinetics and pharmacodynamics of verapamil and norverapamil in rabbits.

We have estimated the pharmacokinetic and pharmacodynamic interactions of verapamil (VP) enantiomers and also the interaction between VP and its metabolite, norverapamil (NVP). ECGs of conscious rabbits were studied to determine the pharmacokinetics of VP enantiomers and racemic NVP in relation to their prolongation effect on PR intervals, which were used as an index of VP's antiarrhythmic effect. Plasma free fractions of VP enantiomers showed constant values at concentrations ranging from 0.022 to 1.10 microm. There were no interactions between enantiomers or between VP and NVP. The pharmacological effect of the S-enantiomer (S-VP), which was determined by linear regression analysis, showed it was about 20 times more potent than that of the R-enantiomer (R-VP). The effect of racemic VP was the simple sum of those elicited by both enantiomers. These relationships were not significantly different between intravenous infusion and bolus injection. Simultaneous intravenous infusion of NVP had no influence on the PR intervals. In conclusion, we demonstrated that the relationship between plasma unbound concentration of VP enantiomers and their pharmacological effect was the simple sum of two enantiomers.

Animals↗

PubMed2001

[Ruptured cerebral aneurysm in childhood--report of two cases].

We report two pediatric patients with rupture of cerebral aneurysm developing subarachnoid hemorrhage. These two patients complained of headache and vomiting. Patient 1 was a 15-year-old girl. Cranial computed tomography (CT) showed a high density area in the left sylvian fissure, suggesting subarachnoid hemorrhage. Left carotid arteriography revealed an aneurysm at the left internal carotid artery bifurcation. Surgical pathology showed a saccular type aneurysm with disappearance of internal elastic membrane. Patient 2 was a 14-year-old girl. Cranial CT exhibited a high density area in the basal cistern and hematoma in the right frontal lobe, penetrating to the right lateral ventricle. Right carotid arteriography showed a right anterior cerebral aneurysm in the right anterior cerebral artery. Both patients underwent craniotomy and trapping successfully, and their subsequent clinical courses were uneventful.

Adolescent↗

PubMed2001

[Indication for surgical and microwave coagulation therapy for multiple (> or = 5) bilobar liver metastases from colorectal cancer].

We analyzed methods and clinicopathological factors for multiple (> or = 5) bilobar liver metastases (H3) from colorectal cancer and evaluated the indication of surgical and microwave coagulation therapy (MCT) for them. Twenty-four patients with H3 underwent surgical therapy and were divided into two groups. Group a: 9 patients with a prognosis of more than 700 days. Group b: the remaining 15 patients. There was no significant difference in prognosis between those receiving MCT and resection + MCT as a surgical therapy. The number and maximum diameter of tumors tended to be smaller in Group a. The number of tumors was less than or equal to 9 and the maximum size of the tumors was 38 mm. Moreover, the tumor could be controlled by MCT alone if the tumor size was less than 30 mm. MCT is a useful therapy for these cases and the indication for surgical therapy may depend on the number and maximum size of tumors.

Colorectal Neoplasms↗

PubMed2001

[Comparison of microwave coagulation using a new type electrode with radiofrequency ablation in the liver of living animals].

In the present study, we compared microwave coagulation using a new type of electrode, a teflon-coated electrode that was developed in order to increase the area of coagulation, with radiofrequency ablation using a Radionics Cool-tip electrode inserted into the pig liver. Two Landrace male pig were put under general anesthesia. A microwave electrode (insulated area: 6 mm, teflon-coated electrode 16 G) and a radiofreqency (RF) electrode (Cool-tip RF single electrode 17 G) were passed through the surface of the livers of the pig. A thermometer was placed 1 cm from the tip of the electrode in order to measure the changes in the temperature of the area surrounding the electrode. In this study, the microwave setting was 80 W, and the RF pulse was set automatically. The coagulated and ablated areas of the liver were measured after 2.5, 5, and 10 minutes of energy delivery (n = 4). The diameter of the coagulated area of the liver following 2.5, 5 and 10 minutes of microwave exposure was 23.5 +/- 4.8 mm, 29.5 +/- 5.2 mm and 32.5 +/- 6.4 mm, respectively. On the other hand, the diameter of the ablated area of the liver following 2.5, 5 and 10 minutes of RF exposure was 18.5 +/- 4.1 mm, 24 +/- 7.8 mm and 28 +/- 4.9 mm, respectively. The mean temperature of the liver 1 cm from the microwave and RF electrodes (measured time: 2 minutes) was 69.6 degrees C and 56.3 degrees C. respectively (n = 12). Thus, the temperature of the area surrounding the microwave electrode was significantly higher than the temperature of the area surrounding the RF electrode (p = 0.0065). The teflon-coated microwave electrode achieved superior results to the Radionics Cool-tip electrode with respect to the diameter of the coagulated area and the temperature of the area in which the electrode was inserted, at the specified times.

Animals↗

PubMed2000

Initial homotypic cell pair adhesion in regenerating Hydra facilitates subsequent adhesion of homotypic cells.

In Hydra vulgaris at the level of dissociated single cells endodermal cells adhere to each other more readily than to ectodermal cells at the initial adhesion. The time required for adhesion to occur between two adjacent cells is shorter for both endodermal and ectodermal homotypic cell adhesions once the initial adhesion of the first pair of cells has been established. It is confirmed that contact of an aggregated pair with additional homotypic cells facilitates the occurrence of homotypic adhesions; heterotypic adhesions are discouraged. This suggests that adhesion of homotypic cells contributes to an increased readiness for subsequent homotypic cells to adhere.

Animals↗

PubMed2000

Elastic measurements of layered nanocomposite materials by Brillouin spectroscopy

Surface Brillouin spectroscopy makes it possible to measure surface elastic wave propagation parameters at frequencies up to 20 GHz or more. This enables us to measure the elastic properties of surface layers only a small fraction of a micrometre thick. The wavelength and incident angle of the light determine the wavenumber of surface elastic waves (SAW) that scatter the light inelastically, and their frequency can be found by measuring the change in wavelength of the scattered light. By analysing the elastic wave modes present in the surface, the elastic properties can be deduced. We have used this technique to measure the elastic properties of layered nanocomposite materials, which are widely used in the packaging industry. 12 microns polymer films (PET) were coated with glass oxide layers of thickness as little as 25 nm, to give transparent nanocomposite structures with excellent gas barrier properties. In order to understand and model the behaviour of these films under deformation, it is necessary to determine the elastic properties of the different layers. Evaluation of the elastic properties presents several challenges. First, the oxide layers are much thinner than the wavelengths of the surface phonons in surface Brillouin spectroscopy (and hence the depth probed), which usually lie in the range 250-500 nm. The anisotropic elastic properties of the PET substrate must therefore be measured accurately, and this can be done using bulk Brillouin spectroscopy. Second, a thin layer of metal (usually 10-20 nm) must be deposited on the glass surface so that the surface phonons scatter the light effectively. The elastic properties of the glass layer can then be deduced from surface Brillouin spectroscopy measurements, by simulating the surface wave modes of the metal/glass/polymer composite, and adjusting the parameters to give the best fit. In this way it is possible to observe how the properties of the glass vary as a function of thickness, and in turn to understand how to improve systematically the properties under deformation.

Journal Article↗

PubMed2000

Photoparoxysmal response elicited by flickering dot pattern stimulation to the center and periphery.

OBJECTIVE: We performed this study to elucidate the roles of stimulus spatial frequency and visual field in eliciting generalized photoparoxysmal response (PPR) by flickering dot pattern (FDP) stimulation. METHODS: We studied 20 photosensitive epilepsy patients, aged 7-48 years (means +/- SD, 21.4+/-11.7 years), producing a 20 Hz FDP stimulation with a strobo-filter. Using dot patterns (0.5, 1, 2, 4 and 6 mm in diameter), we gave FDP stimulation to the center (11x11 degrees ) and periphery (11-30x11-30 degrees ) of subjects with eyes open, and analyzed each PPR appearance latency. RESULTS: Significant results were: latency by 1 (2.1 c/deg) and 0.5 mm (4.9 c/deg) FDP stimulation to the center was shorter than that to the periphery; latency by 4 mm (0.8 c/deg) FDP stimulation to the periphery was shorter than that to the center. As for 2 (1.5 c/deg) and 6 mm (0.5 c/deg) FDP stimuli, no significant difference could be observed. CONCLUSIONS: A higher spatial frequency FDP stimulation to the center elicits PPR more strongly than that to the periphery, whereas a lower spatial frequency FDP stimulation showed the opposite result, with peripheral stimulation being more effective than central stimulation.

Adolescent↗

PubMed2000

[Clinical efficacy of cefpirome sulfate against Bacteroides species, Prevotella species and Porphyromonas species. Society of Anaerobic Bacterial Infections in the fields of obstetrics and gynecology in Gifu].

The injectable cephalosporin cefpirome (CPR) was launched in Japan in 1993. It has widely been used in the various infectious diseases. We therefore studied the clinical and bacteriological efficacy of CPR against infections caused by Bacteroides species, Prevotella species and Porphyromonas species frequently isolated from the obstetric and gynecologic infections. Thirteen institutions were involved in this study which ran from March 1994 to January 1999. The administration dosage of CPR was 2 to 4 gram per day administered by drip infusion or intravenous infusion. The duration of treatment was from 3 to 15 days. The evaluations were performed before and after the treatment. CPR was administered to 194 patients with obstetric and gynecologic infections, and 146 of 194 cases were acceptable for the evaluation of drug efficacy. Bacteroides species were identified in 102 patients. Clinical efficacy in 146 cases was excellent in 12 patients, good in 110, fair in 9 and poor in 15 patients. The eradication rate for Bacteroides species could be in 37 cases out of 54 evaluable cases; Prevotella species in 38 out of 49; and Porphyromonas species in 5 out of 5. The overall assessment of bacteriological efficacy was "eradicated" in 91 cases out of 133 (68.4%). Adverse reactions including abnormal findings in laboratory tests were seen in 8 patients (4.76%). Based on these results, CPR promises efficacy and safety in the treatment of obstetric and gynecologic infections due to Bacteroides species.

Adult↗