Biomedical subjects

K Takahama

Publications and source records attributed to K Takahama.

At least 19 recordsLinked to original sources

PubMed2001

Interaction between beta-adrenergic signaling and protein kinase C increases cytoplasmic Ca2+ in alveolar type II cells.

The interaction between beta-adrenergic signaling and the activation of protein kinase C in alveolar type II cell plays an important role in the regulation of surfactant secretion because the combined application of beta-adrenergic agonist with protein kinase C activator to the cells stimulates the secretion synergistically. However, the mechanisms underlying the interaction are not clear. In the present study, we examined the combined effect of terbutaline with phorbol 12-myristate 13-acetate (PMA) on cytoplasmic free Ca2+ concentration ([Ca2+]i) in rat alveolar type II cells. The combined application of terbutaline with PMA to the cells rapidly increased [Ca2+]i, although neither of them affected it by itself. Similar increases of [Ca2+]i were observed in other combinations, such as terbutaline with 1-oleoyl-2-acetyl-sn-glycerol, and forskolin with PMA. Either the removal of extracellular Ca2+ or the addition of Co2+ remarkably suppressed the increase of [Ca2+]i induced by the combination of terbutaline with PMA. In addition, Co2+ inhibited the phosphatidylcholine secretion induced by the combination of terbutaline and PMA. These results suggested that the [Ca2+]i increased as a result of the interaction between formation of cyclic AMP and activation of protein kinase C in alveolar type II cells, and that the increase in [Ca2+]i was mediated by the Ca2+ influx through the plasma membrane. This mechanism to modulate [Ca2+]i may play a role in the regulation of surfactant secretion by alveolar type II cells.

Adenosine Triphosphate↗

PubMed2001

Activation of potassium conductance by ophiopogonin-D in acutely dissociated rat paratracheal neurones.

1. The effect of ophiopogonin-D (OP-D), a steroidal glycoside and an active component of Bakumondo-to, a Chinese herbal antitussive, on neurones acutely dissociated from paratracheal ganglia of 2-week-old Wistar rats was investigated using the nystatin-perforated patch recording configuration. 2. Under current-clamp conditions, OP-D (10 microM) hyperpolarized the paratracheal neurones from a resting membrane potential of -65.7 to -73.5 mV. 3. At the concentration of 1 microM and above, OP-D concentration-dependently activated an outward current accompanied by an increase in the membrane conductance under voltage-clamp conditions at a holding potential of -40 mV. 4. The reversal potential of the OP-D-induced current (I(OP-D)) was -79.4 mV, which is close to the K(+) equilibrium potential of -86.4 mV. The changes in the reversal potential for a 10 fold change in extracellular K(+) concentration was 53.1 mV, indicating that the current was carried by K(+). 5. The I(OP-D) was blocked by an extracellular application of 1 mM Ba2+ by 59.0%, but other K(+) channel blockers, including 4-aminopyridine (3 mM), apamin (1 microM), charybdotoxin (0.3 microM), glibenclamide (1 microM), tolbutamide (0.3 mM) and tetraethylammonium (10 mM), did not inhibit the I(OP-D). 6. OP-D also inhibited the ACh- and bradykinin-induced depolarizing responses which were accompanied with firing of action potentials. 7. The results suggest that OP-D may be of benefit in reducing the excitability of airway parasympathetic ganglion neurones and consequently cholinergic control of airway function and further, that the hyperpolarizing effect of OP-D on paratracheal neurones via an activation of K(+) channels might explain a part of mechanisms of the antitussive action of the agent.

Action Potentials↗

PubMed2001

Two members of the IgLON family are expressed in a restricted region of the developing chick brain and neural crest.

The precise expression patterns of two IgLON genes, CEPU-1 and limbic system-associated membrane protein (LAMP), were studied during early embryogenesis. It was found that expression of both was localized to restricted regions of the brain and neural crest. In the developing neural tube, CEPU-1 was expressed in the isthmus and a restricted region of the hindbrain, whereas LAMP was expressed in the anterior midbrain. Most neural crest cells expressed LAMP, whereas CEPU-1 expression was limited to crest cells derived from the hindbrain. These results suggest that members of the IgLON family have important roles during embryogenesis, particularly in brain formation and differentiation.

Animals↗

PubMed2001

Contrast-enhanced T1-weighted black-blood fast spin-echo MR imaging of the brain. Technique for suppression of enhancing venous signal.

PURPOSE: Contrast-enhanced T1-weighted black-blood fast spin-echo MR imaging (BB-FSE) was performed to suppress enhancing venous signal and flow artifacts in the brain without sacrificing the T1-weighted imaging contrast. MATERIAL AND METHODS: Twenty-five MR imaging sections (17 transverse and 8 coronal images) in 15 patients with various brain diseases were obtained by contrast-enhanced T1-weighted SE and BB-FSE images. RESULTS: In contrast-enhanced T1-weighted BB-FSE images, venous signal was significantly less and T1-weighted contrast of the brain was more evident. No differences in flow artifacts were found between the two imaging techniques. The interobserver agreements were good for the venous signal and flow artifacts using both techniques. CONCLUSION: Contrast-enhanced T1-weighted BB-FSE imaging reduced the venous signal in the brain with maintaining T1-weighted contrast. This novel MR technique can be used when the suppression of enhancing venous signal is expected to improve the depiction of enhancing lesions in the brain.

Adult↗

PubMed2001

[Intestinal permeability in Crohn's disease and effects of elemental dietary therapy].

Enteral intake of non-metabolic monosacharide and disaccharide, followed by measurement of the urinary excretion ratio of the two, is a method used to investigate intestinal permeability. L/R ratio (lactulose/1-rhamnose urinary excretion ratio) is considered an indicator of permeability of the small intestine. An increased L/R ratio is caused by mucosal disorders of the small intestine. The L/R ratio in all patients (n = 92) with Crohn's disease was 0.079 +/- 0.081 (mean +/- S.D.), which was significantly higher than the value in normal controls (0.027 +/- 0.009, n = 20, p < 0.05). In 39 patients with Crohn's disease, we assessed intestinal permeability before after treatment with an elemental diet, and during remission. The L/R ratio was 0.120 +/- 0.092, before treatment and 0.065 +/- 0.097 after treatment (p < 0.05), showing increased intestinal permeability before elemental dietary treatment. During remission, the L/R ratio was 0.035 +/- 0.028; this did not differ significantly from the value obtained after treatment. We conclude that intestinal permeability is useful for investigating disease activity in patients with Crohn's disease.

Adolescent↗

PubMed2000

A sandwich enzyme immunoassay for human pancreatic elastase III.

To develop a method for the determination of pancreas injuries using a pancreas-specific antigen as a marker, human elastase III was purified from the pancreas by chromatographic methods. A rabbit anti-human elastase III antibody was prepared, and this antibody was confirmed using immunoblotting to react only with elastase III among proteins from the pancreas. A sensitive sandwich enzyme immunoassay for human elastase III was developed. The detection limit for human elastase III was 0.3 pg (10 amol) per assay. Proteins extracted from the pancreas showed the strongest response, whereas reactions of the other organs were less than the detection limit. These results suggest that a sandwich enzyme immunoassay for human elastase III is useful for the determination of pancreas injury.

Animals↗

PubMed2000

A sandwich enzyme immunoassay for pulmonary surfactant protein D and measurement of its blood levels in drowning victims.

A sensitive sandwich enzyme immunoassay for human pulmonary surfactant protein D (SP-D) was developed and used to examine the blood SP-D levels of drowning victims. Human SP-D was purified from amniotic fluid by chromatographic methods, and an antibody against human SP-D was prepared. A polystyrene ball coated with anti-SP-D IgG was incubated with purified human SP-D, and then with anti-SP-D Fab'-peroxidase conjugate. Peroxidase activity bound to the polystyrene ball was assayed by fluorometry using 3-(4-hydroxyphenyl)propionic acid as the hydrogen donor. The detection limit of human SP-D was 5.2 pg per assay tube. Examination of cross-reactions of this sandwich enzyme immunoassay with proteins from other human organs showed it to be highly specific for lung, and Northern blot analysis detected specific SP-D mRNA expression only in lung. The SP-D concentration of normal human serum was 6.4+/-2.7 (mean+/-S.D.) ng ml(-1) (n=20). The recovery rates of 0.52 ng and 5.2 ng SP-D added to 5 microl normal human serum were 93.6+/-2.7% and 93.6+/-6.1%, respectively. Blood SP-D levels of victims from the saltwater drowning group (n=14) revealed higher concentrations (105.8+/-53.7 ng ml(-1)), while freshwater drowning victims (n=12) were estimated to be 74.1+/-43.9 ng ml(-1). The SP-D levels of 15 subjects who died of hemorrhage (n=5), heart failure (n=8), traumatic shock (n=1), and electrocution (n=1) were lower (22.0+/-8.5 ng ml(-1)), and those of asphyxia victims (n=10) were slightly higher (36.2+/-17.1 ng ml(-1)) than those of other causes of death, except for drowning. These results suggest that in drowning victims, SP-D flowed into the systemic circulation by physiological and physical mechanisms, and the differences of blood SP-D levels between saltwater drowning and freshwater drowning victims are presumed to be influenced by the type of agony and/or the length of survival time in water.

Adolescent↗

PubMed2000

Preferential inhibition of L- and N-type calcium channels in the rat hippocampal neurons by cilnidipine.

The effect of a dihydropyridine Ca2+ antagonist, cilnidipine, on voltage-dependent Ca2+ channels was studied in acutely dissociated rat CA1 pyramidal neurons using the nystatin-perforated patch recording configuration under voltage-clamp conditions. Cilnidipine had no effect on low-voltage-activated (LVA) Ca2+ channels at the low concentrations under 10(-6) M. On the other hand, cilnidipine inhibited the high-voltage-activated (HVA) Ca2+ current (I(Ca)) in a concentration-dependent manner and the inhibition curve showed a step-wise pattern; cilnidipine selectively reduced only L-type HVA I(Ca) at the low concentrations under 10(-7) and 10(-6) M cilnidipine blocked not only L- but also N-type HVA I(Ca). At the high concentration over 10(-6) M cilnidipine non-selectively blocked the T-type LVA and P/Q- and R-type HVA Ca2+ channels. This is the first report that cilnidipine at lower concentration of 10(-6) M blocks both L-and N-type HVA I(Ca) in the hippocampal neurons.

Animals↗

PubMed2000

Inhibition of the 5-HT(1A) receptor-mediated inwardly rectifying K(+) current by dextromethorphan in rat dorsal raphe neurones.

The effect of dextromethorphan (DM) on the inwardly rectifying K(+) currents mediated by 5-HT(1A) receptors in acutely dissociated dorsal raphe (DR) neurones of rats was studied using nystatin-perforated patch and conventional whole-cell patch recording configurations under voltage-clamp conditions. DM rapidly and reversibly inhibited the K(+) currents induced by 10(-7) M 5-HT in a concentration-dependent manner with a half-maximum inhibitory concentration of 1.43 x 10(-5) M. The inhibitory effect of DM was neither voltage- nor use-dependent. DM caused a suppression of the maximum response of the 5-HT concentration-response curve, thus suggesting a non-competitive type of inhibition. In neurones perfused intracellularly with a pipette-solution containing the nonhydrolyzable GTP analog GTPgammaS, 5-HT activated K(+) currents in an irreversible manner. DM suppressed the current irreversibly activated by intracellular GTPgammaS even in the absence of the agonist. DM also inhibited the inwardly rectifying K(+) currents regulated by alpha(2)-adrenoceptors in freshly isolated rat locus coeruleus neurones. These results suggest that DM may inhibit the G-protein coupled inwardly rectifying K(+) channels, but not the neurotransmitter receptors, in the central nervous system.

Animals↗

PubMed2000

Toxicity of methylmercury conjugated with L-cysteine on rat thymocytes and human leukemia K562 cells in comparison with that of methylmercury chloride.

In order to reveal the implication of use of methylmercury chloride (MeHgCl) in in vitro study, the effects of 10 µM MeHgCl on rat thymocytes and human leukemia K562 cells were compared with those of methylmercury conjugated with L-cysteine (10 µM MeHg-Cys) using a flow cytometer and fluorescent probes to monitor cellular physiological and pathological parameters. MeHgCl hyperpolarized membranes of thymocytes, followed by depolarization within a few minutes after the application, while MeHg-Cys persistently hyperpolarized them. MeHgCl increased intracellular concentration of Ca(2+), decreased cellular content of glutathione and increased generation of superoxide anion in the cells. The effects of MeHg-Cys were much less than those of MeHgCl. MeHgCl greatly increased both numbers of the cells undergoing apoptosis and dead cells in cell suspension containing thymocytes, while this was not the case for MeHg-Cys. MeHgCl reduced the cell viability of human leukemia K562 cells and completely inhibited the cell growth. The effects of MeHg-Cys on K562 cells were less than those of MeHgCl. It can be concluded that the effects of MeHgCl on rat thymocytes and K562 cells are different from those of MeHg-Cys. The results obtained from the in vitro studies using MeHgCl may be less implicit to elucidate the mechanism of MeHg intoxication in humans and experimental animals because MeHg are present in forms of MeHg-Cys and/or MeHg-S conjugate under the in vivo conditions.

Journal Article↗

PubMed2000

Identification of remains by sequencing of mitochondrial DNA control region.

The maternity of two newborns who were murdered and abandoned >5 and 10 years were analyzed by amplification and direct sequencing of mitochondrial DNA (mtDNA) control regions. Sequences of two hypervariable segments from each femur bone sample and the blood of the putative mother showed four mutations in hypervariable region I and two mutations in addition to two nucleotide insertions in hypervariable region II compared with the reference sequence, and all sequences were identical. The genotype of these individuals is found to be relatively rare in the Japanese population, and it was strongly suggested that both sets of newborn remains really were children of the putative mother. Sexes of the remains were determined to be female and male by amplifying a segment of the X-Y homologous gene, amelogenin. These results demonstrate that sequencing of mtDNA is a useful tool for genetic identification of aged and decomposed materials.

Amelogenin↗

PubMed2000

Investigation of the association between infection with Helicobacter pylori and with TT virus, a novel DNA virus, in patients with gastroduodenal ulcer or ulcer scar.

OBJECTIVE: Recently, a novel DNA virus (TT virus; TTV) has been isolated. Enteric transmission is suggested as a route of transmission of TTV, with high prevalence of this virus infection in the general population, and age and geographical distributions of TTV prevalence very similar to those of Helicobacterpylori infection. We analysed an association between TTV and H. pylori infection in patients with gastroduodenal ulcer or ulcer scar. METHODS: In 181 patients with a gastroduodenal ulcer or ulcer scar (102 with a gastric lesion, 60 with a duodenal lesion, and 19 with both sites involved), specimens were cultured for H. pylori and TTV infection was sought in serum by a polymerase chain reaction. RESULTS: H. pylori infection was demonstrated in 152 patients (84.0%) and TTV was detected in 168 patients (92.8%). Patients with TTV were significantly older than those without TTV (P = 0.0001), while no age difference was observed between patients with and without H. pylori infection. No difference was apparent in the prevalence of TTV infection between patients with and without H. pylori infection, and vice versa. CONCLUSIONS: We found no association between TTV infection and H. pylori infection in patients with peptic ulcer diseases, which is consistent with a lack of association between TTV infection and peptic ulcer. However, larger studies including surveys of the general population will be required to analyse the overall association between TTV and H. pylori.

Adult↗

PubMed2000

Non-competitive inhibition of kainate-induced currents by diethylstilbestrol in acutely isolated mouse CA1 hippocampal neurons.

The effect of a synthetic estrogen, diethylstilbestrol (DES), on kainate-induced currents was investigated in the hippocampal CA1 pyramidal neurons acutely dissociated from the mice using the nystatin-perforated patch-clamp recording configuration under voltage-clamp conditions. DES inhibited the current evoked by 100 microM kainate in a concentration-dependent manner with a half-maximum inhibitory concentration of 8.8 microM. The action of DES was voltage-independent. Since DES produced a suppression of the maximum response of the kainate concentration-response curve, the inhibition by DES of the kainate-induced current appears to be non-competitive.

Animals↗

PubMed2000

[Survey on postmortem examination to police surgeons and emergency physicians. Possibility of physicians' assist in mass-disaster].

We conducted a questionnaire survey of police surgeons and emergency physicians, inquiring about their experience of medicolegal investigation of death and their willingness to join a death investigation team in a major disaster. The questionnaire also asked about their knowledge about and interest in the forensic specialist system established by the Japanese Society of Legal Medicine. Police surgeons were generally willing to join an investigation team only if a disaster occurred in or close to their hometown, because they could not afford more than several days away from patient care. Although many of the emergency physicians were willing to join a death investigation team, they had difficulty in doing so without permission or orders from their employer or the authorities concerned. The survey found that the percentage of aged police surgeons was increasing among those surveyed. This fact, in combination with the current emphasis of postgraduate education on specialty training, threatens to cause a substantial lack of physicians available for medicolegal investigation of death. Therefore, it is urgently necessary to establish a system of training resident and emergency physicians in medicolegal investigation of death. In addition to providing postgraduate training in medicolegal investigation of death to prospective trainees who are emergency physicians at major hospitals in potential disaster-stricken areas, the medical school should incorporate forensic medicine in postgraduate training programs so that they can actively perform death investigation on disaster victims dying before or after arrival at their hospitals. Furthermore, the forensic community should make every effort to increase the number of autopsies in each department of forensic medicine and to expand the medical examiner system throughout Japan that is currently in practice only in the Metropolis of Tokyo and Yokohama, Nagoya, Osaka and Kobe Cities in order to incorporate forensic training in the postgraduate clinical training programs that will become compulsory in 2004.

Attitude of Health Personnel↗

PubMed1999

A sandwich enzyme immunoassay for human muscle-specific beta-enolase and its application for the determination of skeletal muscle injury.

A sensitive sandwich enzyme immunoassay for human beta-enolase was developed and used to examine beta-enolase in blood or bloodstains as a marker for the determination of skeletal muscle injury. Human beta-enolase was purified from human skeletal muscle, and then an antibody against it was prepared. Polystyrene balls coated with rabbit anti-human beta-enolase IgG were incubated with human beta-enolase and then with anti-human beta-enolase Fab'-peroxidase conjugate. Peroxidase activity bound to the polystyrene balls was assayed by fluorometry using 3-(4-hydroxyphenyl)propionic acid as a hydrogen donor. The detection limit for human beta-enolase was 2.6 pg (30 amol) per assay. The degree of cross-reaction of the sandwich enzyme immunoassay for other organs except for heart (1/10) was about 1/150 or less. Moreover, the localization of beta-enolase in various human tissues was examined by Northern blot analysis, and this confirmed that beta-enolase was expressed only in skeletal and cardiac muscle. Antigenic activity in bloodstains containing beta-enolase was recovered well after storage for 60 days at room temperature. The ratio of beta-enolase to total protein in bloodstains made from non-traumatic blood, nasal hemorrhage and menstrual blood, was within the normal range. In contrast, the ratio of beta-enolase in bloodstains from traumatic blood was obviously elevated (10-30 fold) in comparison with non-traumatic blood. Furthermore, the ratio of beta-enolase was proved to be higher in stains adhering to weapons that had passed through skeletal muscle, indicating that detection of beta-enolase in bloodstains could be used to distinguish crime weapons. These results suggest that beta-enolase is a useful marker for identification of skeletal muscle injury as well as for detecting the origin of bleeding.

Animals↗

PubMed1999

Left ventricular function at rest and during bicycle exercise in normal subjects: assessment by ECG-gated myocardial perfusion SPET with 99Tcm-tetrofosmin.

99Tcm-labelled myocardial perfusion tracers allow simultaneous assessment of myocardial perfusion and left ventricular function using ECG-gated SPET. The aim of this study was to evaluate left ventricular performance during exercise by means of ECG-gated myocardial perfusion SPET. After the administration of 99Tcm-tetrofosmin (555-740 MBq), eight healthy volunteers aged 27-49 years underwent ECG-gated myocardial perfusion SPET at rest and during supine submaximal exercise (75 and 125 W), for 3 min each. Using ECG-gated SPET data, left ventricular end-diastolic volume (LVEDV) demonstrated a biphasic response during exercise (from 106.4 +/- 17.5 to 119.9 +/- 19.9 to 108.1 +/- 19.2 ml). In contrast, left ventricular end-systolic volume decreased gradually and significantly during exercise (from 47.1 +/- 11.9 to 41.5 +/- 8.9 to 36.1 +/- 10.1 ml; P < 0.05), and left ventricular ejection fraction continued to increase at higher workloads (from 56.1 +/- 6.0 to 63.0 +/- 2.7 to 67.0 +/- 4.3; P < 0.01) despite a fall in LVEDV. There was a progressive increase in cardiac output during exercise, which reached a peak of 7.2 +/- 0.9 l.min-1. We conclude that ECG-gated myocardial perfusion SPET can assess left ventricular function during exercise and may provide useful information for the evaluation of patients with ischaemic heart disease.

Adult↗

PubMed1999

Mucolytic and antitussive effects of erdosteine.

To investigate the influence of erdosteine, a new homocysteine-derived expectorant, on airway clearance we studied the effects of the drug on the viscosity of mucin, on the mucociliary transport rate in quails, on airway secretion in rats and on the cough reflex in guinea-pigs. The active metabolite of erdosteine, M1 (10 microM to 1 mM), significantly reduced the viscosity of porcine stomach mucin. Erdosteine by itself did not reduce viscosity. Erdosteine significantly promoted mucociliary transport in quails and increased airway secretion in rats. The effect was still apparent 24h after administration. Erdosteine significantly suppressed citric acid-induced cough reflexes in guinea-pigs but did not suppress mechanical stimuli-induced cough reflexes. Erdosteine suppressed the reduction of the recovery volume of bronchoalveolar lavage fluid and albumin leakage into the fluid in citric acid-exposed guinea-pigs. These results indicate that erdosteine removes sputum by reducing its viscosity, and by promoting mucociliary transport and sustained enhancement of airway secretion. It also suppressed the chemical stimulation-induced cough reflex and plasma leakage into the airway. These results suggest that erdosteine is an excellent expectorant with several modes of action.

Animals↗

PubMed1999

[Composition of vascular tree using moving-table MR angiography: development and preliminary clinical experience with a semi-automated program combining stacks of MR angiographic images].

Moving-table MR angiography, combining a contrast enhanced MRA approach with table movement, has recently become available. This technique allows imaging of long, longitudinal anatomical regions of vasculature. We have developed a semi-automated program combining stacks of MRA images obtained from different image stations, and applied it to the reconstruction of vascular trees in twenty-five patients with peripheral arterial occlusive disease. Using this program, continuous vascular trees, extending from the abdominal aorta to lower leg (up to 124 cm), were semi-automatically reconstructed within two minutes from six different projection angles. Extensive vascular lesions were recognized three-dimensionally by moving image display mode.

Arterial Occlusive Diseases↗