Biomedical subjects

N Hagiwara

Publications and source records attributed to N Hagiwara.

At least 37 records · Page 2Linked to original sources

PubMed2000

Review article: acute inorganic mercury vapor inhalation poisoning.

Mercury contamination is a serious environmental problem worldwide. Two primary sources of contamination are dumping of large quantities of inorganic mercury and exposure in the mining industry. Although the actual fatal level of mercury vapor is not known, exposure to more than 1-2 mg/m3 of elemental mercury vapor (Hg0) for a few hours causes acute chemical bronchiolitis and pneumonitis. Two hours after exposure, lung injury appears as hyaline membrane formation, and finally, extensive pulmonary fibrosis occurs. Clinical findings correlate with the duration of exposure, the concentration of mercury, and the survival time after exposure. There is no correlation between pathological findings and the concentration of mercury in the tissues. Necrosis of proximal convoluted tubules may be attributed to the disruption of the enzyme systems of Hg2+-sulfhydryl compounds. Metallothionein protein (MT), induced by the accumulation of Hg2+ in the kidneys, may play an important role in detoxication after it forms a non-toxic Hg2+-MT compound. Despite the deposition of mercury in the brain, compared with organic mercury, inorganic mercury did not seem to damage the neurons. Drugs such as chelating agents and corticosteroids appear to effectively decrease the inflammation and delay pulmonary fibrosis.

Environmental Exposure↗

PubMed2000

Quantitative detection of binding of PCNA protein to DNA strands on a 27 MHz quartz-crystal microbalance.

We report here binding kinetics of proliferating cell nuclear antigen (PCNA) to the dsDNA immobilized on a 27 MHz quartz-crystal microbalance. PCNA is a toroidal-shaped protein and encircles dsDNA sliding along the strand. The binding behavior of this sliding clamp protein was compared with those of other side binding proteins such as GCN4-bZIP and Zn-finger peptides.

Base Sequence↗

PubMed2000

[Clinical evaluation of rapid diagnostic kit detecting separately influenza A and B viruses].

The Directigen Flu A + B kit, a rapid diagnostic device for influenza virus A and B was evaluated. The nasopharyngeal aspirates were obtained from 239 patients who visited our hospital, between January and March, 2000, presenting flu-like symptoms. Influenza virus AH1: 77 and AH3: 51 were isolated from 128 specimens and none from 111 specimens. Directigen Flu A + B showed 115 specimens positive and 106 specimens negative. The sensitivity and specificity of this kit were 89.8% (115/128) and 95.5% (106/111) compared with viral isolation. Agreement on positive and negative interpretations between Direction Flu A and this kit was 97.9% (234/239). In the evaluation of this kit for influenza B virus, 60 frozen nasopharyngeal aspirates collected from February to April, 1999 were used. The sensitivity and specificity of this kit were 88.9% (16/18) and 88.1% (37/42) compared with viral isolation. Agreement on positive and negative interpretations between FLU OIA and this kit was 91.7% (55/60). The Directigen A + B demonstrated sensitivity and specificity equivalent to the conventional kits in nasopharingeal aspirates. This kit can also differentiate influenza A and B viruses, a feature which is useful for treatment using anti-viral agents such as amantadine and neuraminidase inhibitor. To date, the kit is the most effective tool for the rapid diagnosis of influenza.

Evaluation Studies as Topic↗

PubMed2000

Detection of circulating anti-p53 antibodies in esophageal cancer patients.

It has been reported that circulating anti-p53 antibodies (p53-Ab) in the serum are detected in some cancers. To investigate the usefulness of detecting p53-Ab, we measured the circulating p53-Ab in comparison with squamous cell carcinoma antigen (SCC-Ag) in patients with esophageal carcinoma. Serum specimens from 46 esophageal cancer patients (42 squamous cell carcinomas, 3 mucoepidermoid carcinomas and 1 basaloid squamous carcinoma) and 13 healthy subjects were studied. Serum p53-Ab was measured by an enzyme-linked immunosorbent assay. Surgically resected specimens from 43 patients were immunohistochemically stained for p53. Serum SCC-Ag was measured by a radioimmunoassay. The results were analyzed with the clinical data and outcome. Serum p53-Ab was detected in 13 (28%) of the 46 patients, but not in any of the healthy subjects. The positive rate was 0% (0/6) in stage I, 60% (3/5) in stage IIA, 30% (3/10) in stage IIB, 29% (7/24) in stage III and 0% (0/1) in stage IV. There was no difference in the outcome between the p53-Ab-positive and p53-Ab-negative patients. Immunohistochemically, 30 (70%) of the 43 specimens stained positively for p53. Serum p53-Ab was detected in 43% (13/30) of the patients with tumors which stained positively for p53. There was a close correlation between positivity for p53 immunostaining and positivity for p53-Ab (p<0.01). An elevated level of SCC-Ag was found in only 13%of the patients, and most patients positive for SCC-Ag already had advanced disease with lymph node metastasis and invasion to the adventitia. In conclusion, serum p53-Ab was detected in Japanese esophageal cancer patients at a frequency similar to that reported in Western countries. Serum p53-Ab may be a potentially useful molecular marker for detection and screening of esophageal cancer. Further studies of a large population may be required to elucidate the true diagnostic usefulness of measuring the serum p53-Ab.

Aged↗

PubMed2000

[A clinical study on active vitamin D pulse therapy in hemodialysis patients with secondary hyperparathyroidism].

The oral active vitamin D pulse therapy was performed for 20 chronic hemodialysis patients with secondary hyperparathyroidism (2 degrees HPT). Before pulse therapy, all patients showed high-turnover bone diseases, elevated serum alkaline phosphatase (Alp) and elevated serum parathyroid hormone (PTH). They had at least one parathyroid gland detected by ultrasonography. In one patient, serum PTH level did not decrease during three months. In five patients, hypercalcemia was observed so that the pulse therapy was with drawn. Another patient was resistant to the second pulse therapy for recurrence of 2 degrees HPT. Total parathyroidectomy and autotransplantation was performed in these seven patients. The size of parathyroid gland in patients undergoing surgical treatment was significantly larger than those estimated by ultrasonography in patients successfully treated with pulse therapy (p < 0.005). In all patients with surgical treatment, the conventional oral active vitamin D therapy was performed with caution to hypercalcemia preoperatively. The preoperative Alp levels decreased compared with those of at the beginning of the pulse therapy. Postoperatively, the total amount of intravenous administered calcium decreased, and serum calcium levels were easily controlled.

Administration, Oral↗

PubMed2000

[Efficacy of continuous intravenous drip infusion of disopyramide in hypertrophic obstructive cardiomyopathy during cardiogenic shock: a case report].

A 54-year-old woman was admitted to our hospital complaining of dyspnea due to hypertrophic obstructive cardiomyopathy. On admission, she was treated with 4 antiarrhythmic drugs and 2 beta-blockers. After 4 of these 6 drugs were withdrawn, the left ventricular outflow pressure gradient markedly increased and then she fell into cardiogenic shock. Therefore, disopyramide(600 mg/day) was administered by continuous intravenous drip infusion to reduce the left ventricular outflow pressure gradient. After intravenous administration of disopyramide, the left ventricular outflow pressure gradient markedly decreased from 100 to 16 mmHg and the cardiogenic shock could be improved. Continuous intravenous drip infusion of disopyramide is effective for the treatment of cardiogenic shock due to severe left ventricular outflow obstruction in patients with hypertrophic obstructive cardiomyopathy.

Anti-Arrhythmia Agents↗

PubMed1999

Novel mechanism associated with an inherited cardiac arrhythmia: defective protein trafficking by the mutant HERG (G601S) potassium channel.

BACKGROUND: The congenital long-QT syndrome (LQTS) is an inherited disorder characterized by a prolonged cardiac action potential and a QT interval that leads to arrhythmia. Mutations in the human ether-a-go-go-related gene (HERG), which encodes the rapidly activating component of the delayed rectifier current (IKr), cause chromosome 7-linked LQTS (LQT2). Studies of mutant HERG channels in heterologous systems indicate that the mechanisms mediating LQT2 are varied and include mutant subunits that form channels with altered kinetic properties or nonfunctional mutant subunits. We recently reported a novel missense mutation of HERG (G601S) in an LQTS family that we have characterized in the present work. METHODS AND RESULTS: To elucidate the electrophysiological properties of the G601S mutant channels, we expressed these channels in mammalian cells and Xenopus oocytes. The G601S mutant produced less current than wild-type channels but exhibited no change in kinetic properties or dominant-negative suppression when coexpressed with wild-type subunits. To examine the cellular trafficking of mutant HERG channel subunits, enhanced green fluorescent protein tagging and Western blot analyses were performed. These showed deficient protein trafficking of the G601S mutant to the plasma membrane. CONCLUSIONS: Our results from both the Xenopus oocyte and HEK293 cell expression systems and green fluorescent protein tagging and Western blot analyses support the conclusion that the G601S mutant is a hypomorphic mutation, resulting in a reduced current amplitude. Thus, it represents a novel mechanism underlying LQT2.

Animals↗

PubMed1999

Properties of the transient outward current in rabbit sino-atrial node cells.

The electrophysiological properties of the transient outward current were investigated in voltage-clamped single cells from the rabbit sino-atrial node. To make a regional comparison, some experiments were repeated in atrial myocytes. The current-voltage relationship showed a characteristic outward rectification with an activation threshold of -30 mV. External 4-aminopyridine (0.01-5 mM) inhibited this current in a dose-dependent manner (IC50 = 0.28 mM, Hill coefficient = 1.38). The steady-state inactivation exhibited a half-maximum voltage of -35 mV and a slope factor of -.4 mV. The current density of the transient outward current was 6.3 +/- 0.5 pA/pF in sino-atrial node cells and 12.3 +/- 1.2 pA/pF in atrial cells. The inactivation time constant was faster in sino-atrial node cells (time constants 4.2 +/- 0.5 and 26.0 +/- 0.6 ms, respectively, for the fast and slow components) than in atrial cells (9.7 +/- 1.2 and 44.8 +/- 3.2 ms, respectively). Recovery from inactivation was much faster in sino-atrial node cells (time constants 44.7 +/- 9.0 ms) than in atrial cells (time constants 1.39 +/- 0.32 and 6.70 +/- 0.1 s, respectively, for the fast and slow components). These results suggest that the kinetic properties, as well as the current density, of the transient outward current differs between sino-atrial node and atrial cells. Taking the current density of Ito at +10 mV as 2.5 +/- 0.3 pA/pF gives a total Ito of approximately 100 pA at the peak of the action potential in rabbit sino-atrial node cells. The action potential duration was increased by 24.8 +/- 1.3% by 0.5 mM 4-AP. Thus, Ito may contribute significantly to the repolarization phase in mammalian sino-atrial node cells.

4-Aminopyridine↗

PubMed1999

Effects of propafenone on K currents in human atrial myocytes.

1. The class Ic anti-arrhythmic agent, flecainide is known to inhibit the transient outward K current (Ito) selectively in human atrium. We studied the effects of propafenone, another class Ic antiarrhythmic agent, on K currents in human atrial myocytes using a whole-cell voltage-clamp method. 2. Propafenone inhibited both Ito and the sustained or ultra-rapid delayed rectifier K current (Isus or Ikur) evoked by depolarization pulses. The concentration for half-maximal inhibition (IC50) was 4.9 microM for Ito and 8.6 microM for Isus. Propafenone blocked Ito and Isus in a voltage- and use-independent fashion and accelerated the inactivation time constant of Ito [from 28.3 to 6.7 ms at 10 microM propafenone]. 3. The steady-state inactivation curve for Ito was unaffected by propafenone. Propafenone did not affect the initial current at depolarizing potentials, but it did produce a block that increased as a function of time after depolarization (time constant of 3.4 ms). This suggests that propafenone preferentially blocked Ito in the open state. 4. Propafenone had no significant effect on the rate at which Ito recovered from inactivation at -80 mV suggesting that propafenone dissociates rapidly from the channel. 5. The steady-state activation curve for Isus was not affected by propafenone. Propafenone slowed the time course of the onset of the Isus tail current. This suggests that propafenone blocked Isus in the open state. 6. The present results suggest that, unlike flecainide, propafenone blocks both Ito and Isus in human atrial myocytes in the open state at clinically relevant concentrations.

Anti-Arrhythmia Agents↗

PubMed1999

[Use of a rapid detection assay for influenza virus, on nasal aspirate specimens].

We investigated the usefulness of a rapid antigen detection kit using optical immunoassay for influenza virus (FLU OIA, BioStar, USA). Nasal aspirates were taken from 92 influenza suspected outpatients between March to April of 1999. Compared with virus isolation and PCR, the sensitivity of FLU OIA was 88.5% and 81.6%, and the specificity was 65.2% and 72.2%. All isolated viruses were influenza type B virus. It was difficult to differentiate the weak-positive and negative cases, leading to the rather low specificity, although the assay procedure was easy and quick. FLU OIA may be a useful rapid diagnosis kit for influenza in pediatric outpatient clinics and wards, because it can detect both influenza type A and type B viruses.

Antigens, Viral↗

PubMed1999

[Effects of intravenous and oral administration of ondansetron hydrochloride on chemotherapy-induced nausea and vomiting in patients with esophageal cancer].

The effects of ondansetron hydrochloride (OND) were studied through 11 courses of chemotherapy, including 70 mg/m2 of cisplatin, in 9 patients with advanced esophageal cancer. During the observation period of 5 days, 4 mg of OND was given intravenously on the day of cisplatin infusion and orally for consecutive 4 days, and nausea was controlled by over 70%. Vomiting was controlled by over 80%. The inhibitory effect of OND on nausea and vomiting was found in 72.7% on the day of cisplatin injection and 88.9% overall. No other side effects of OND except slight increases in total bilirubin and LDH were found in any patient. These findings suggest that intravenous and oral administration of OND may inhibit chemotherapy-induced nausea and vomiting in patients with advanced esophageal cancer.

Administration, Oral↗

PubMed1999

Social environmental factors in Japan affecting the development of proper eating behaviors.

This article summarizes issues related to myofunctional disorders/dysphagia and focuses upon social and economic changes within Japanese culture affecting eating habits and behaviors in children. The authors suggest that unfavorable environmental factors negatively impact upon the acquisition of mastication and swallowing behaviors. The article includes discussion of prior research. Studies indicate that decreased observation of early childhood eating habits, dietary changes with regard to higher consumption of fast food and changes within the family, i.e. busy work schedules, decrease in family mealtimes, combine to incur negative change with regard to orofacial function.

Child, Preschool↗

PubMed1997

The mouse pale ear (ep) mutation is the homologue of human Hermansky-Pudlak syndrome.

The recessive mutation at the pale ear (ep) locus on mouse chromosome 19 was found to be the homologue of human Hermansky-Pudlak syndrome (HPS). A positional cloning strategy using yeast artificial chromosomes spanning the HPS locus was used to identify the HPS gene and its murine counterpart. These genes and their predicted proteins are highly conserved at the nucleotide and amino acid levels. Sequence analysis of the mutant ep gene revealed the insertion of an intracisternal A particle element in a protein-coding 3' exon. Here we demonstrate that mice with the ep mutation exhibit abnormalities similar to human HPS patients in melanosomes and platelet-dense granules. These results establish an animal model of HPS and will facilitate biochemical and molecular analyses of the functions of this protein in the membranes of specialized intracellular organelles.

Albinism, Oculocutaneous↗

PubMed1997

Mice devoid of gamma-aminobutyrate type A receptor beta3 subunit have epilepsy, cleft palate, and hypersensitive behavior.

gamma-Aminobutyric acid type A receptors (GABA(A)-Rs) mediate the bulk of rapid inhibitory synaptic transmission in the central nervous system. The beta3 subunit is an essential component of the GABA(A)-R in many brain regions, especially during development, and is implicated in several pathophysiologic processes. We examined mice harboring a beta3 gene inactivated by gene targeting. GABA(A)-R density is approximately halved in brain of beta3-deficient mice, and GABA(A)-R function is severely impaired. Most beta3-deficient mice die as neonates; some neonatal mortality, but not all, is accompanied by cleft palate. beta3-deficient mice that survive are runted until weaning but achieve normal body size by adulthood, although with reduced life span. These mice are fertile but mothers fail to nurture offspring. Brain morphology is grossly normal, but a number of behaviors are abnormal, consistent with the widespread location of the beta3 subunit. The mice are very hyperactive and hyperresponsive to human contact and other sensory stimuli, and often run continuously in tight circles. When held by the tail, they hold all paws in like a ball, which is frequently a sign of neurological impairment. They have difficulty swimming, walking on grids, and fall off platforms and rotarods, although they do not have a jerky gait. beta3-deficient mice display frequent myoclonus and occasional epileptic seizures, documented by electroencephalographic recording. Hyperactivity, lack of coordination, and seizures are consistent with reduced presynaptic inhibition in spinal cord and impaired inhibition in higher cortical centers and/or pleiotropic developmental defects.

Angelman Syndrome↗

PubMed1997

ATP-activated cationic current in rabbit sino-atrial node cells.

The electrophysiological effect of extracellular ATP was investigated in voltage-clamped single cells from the rabbit sino-atrial node. External 0.5 mM ATP consistently activated a time-independent, weakly inwardly rectifying current (2.26 +/- 0.14 pA/pF at -100 mV, n = 23). This external ATP-activated current increased in a dose-dependent manner over the concentration range 0.01 to 1 mM ATP. However, non-hydrolysable ATP analogs (a, beta-methylene ATP and beta,r-methylene ATP) failed to activate this current. Moreover, adenosine, adenosine monophosphate and adenosine diphosphate were all ineffective in eliciting the ATP-activated current over the concentration range 0.5 to 1 mM, suggesting that it is regulated via the P2-purinoreceptor. The permeability sequence for the ATP-activated current among different cations (determined from reversal potential measurements) was 1.09: 1: 1: 0.24: 0.22 for K+, Na+, Cs+, Tris and N-methyl-D-glucamine. The current component was not affected by substitution of external Cl- by aspartate or by the application of a stilbene-derivative Cl- channel blocker. Thus, the ATP-activated current in rabbit sino-atrial node cells was non-selective for monovalent cations, and could be carried by large molecular ions, such as N-methyl-D-glucamine or Tris. We suggest that it might make some contribution to the chronotropic effects seen on release of transmitters from autonomic nerve endings in the heart.

Adenosine↗

PubMed1997

Functional activity of the CFTR Cl- channel in human myocardium.

The cyclic AMP (cAMP)-dependent chloride channel in the heart has been identified in various species as the cystic fibrosis transmembrane conductance regulator (CFTR). Although functional expression of the channel in the human atrium has been reported, we could not induce any cAMP-dependent chloride conductance in the atrial cells even with maximal cAMP stimulation, whereas the conductance could be induced in rabbit ventricular cells. To clarify the discrepancy between the results, we examined the level of CFTR mRNA expression in both conductance-positive (human colonic epithelium and rabbit ventricle) and -negative (human atrium) tissues. Total RNA samples prepared from these tissues were subjected to the reverse transcription-polymerase chain reaction (RT-PCR). While CFTR transcripts were amplified from the conductance-positive samples, no amplified products could be detected from the conductance-negative sample. A nested PCR performed on the RT-PCR products of the conductance-negative sample resulted in successful amplification of the transcripts, indicating that the level of the CFTR mRNA expression in human atrium is extremely low compared with that in colonic epithelium and rabbit ventricle. The same molecular results were observed in human ventricular tissues. A nucleotide sequencing of the amplified transcripts showed that exon 5 of the CFTR gene was not alternatively spliced in human atrium and ventricle, and both the exon 5 spliced and unspliced isoforms were expressed in rabbit ventricle, unlike the findings of previous reports. Our data suggest that the amount of CFTR expressed in human myocardium might be physiologically insufficient to activate detectable cAMP-dependent chloride conductance.

Adolescent↗

PubMed1997

Contribution of phosphodiesterase isozymes to the regulation of the L-type calcium current in human cardiac myocytes.

1. To determine the contribution of the various phosphodiesterase (PDE) isozymes to the regulation of the L-type calcium current (ICa(L)) in the human myocardium, we investigated the effect of selective and non-selective PDE inhibitors on ICa(L) in single human atrial cells by use of the whole-cell patch-clamp method. We repeated some experiments in rabbit atrial myocytes, to make a species comparison. 2. In human atrial cells, 100 microM pimobendan increased ICa(L) (evoked by depolarization to +10 mV from a holding potential of -40 mV) by 250.4 +/- 45.0% (n = 15), with the concentration for half-maximal stimulation (EC50) being 1.13 microM. ICa(L) was increased by 100 microM UD-CG 212 by 174.5 +/- 30.2% (n = 10) with an EC50 value of 1.78 microM in human atrial cells. These two agents inhibit PDE III selectively. 3. A selective PDE IV inhibitor, rolipram (1-100 microM), did not itself affect ICa(L) in human atrial cells. However, 100 microM rolipram significantly enhanced the effect of 100 microM UD-CG 212 on ICa(L) (increase with UD-CG 212 alone, 167.9 +/- 33.9, n = 5; increase with the two agents together, 270.0 +/- 52.2%; n = 5, P < 0.05). Rolipram also enhanced isoprenaline (5 nM)-stimulated ICa(L) by 52.9 +/- 9.3% (n = 5) in human atrial cells. 4. In rabbit atrial cells, ICa(L) at +10 mV was increased by 22.1 +/- 9.0% by UD-CG 212 (n = 10) and by 67.4 +/- 12.0% (n = 10) by pimobendan (each at 100 microM). These values were significantly lower than those obtained in human atrial cells (P < 0.0001). Rolipram (1-100 microM) did not itself affect ICa(L) in rabbit atrial cells. However, ICa(L) was increased by 215.7 +/- 65.2% (n = 10) by the combination of 100 microM UD-CG 212 and 100 microM rolipram. This value was almost 10 times larger than that obtained for the effect of 100 microM UD-CG 212 alone. 5. These results imply a species difference: in the human atrium, the PDE III isoform seems dominant, whereas PDE IV may be more important in the rabbit atrium for regulating ICa(L). However, PDE IV might contribute significantly to the regulation of intracellular cyclic AMP in human myocardium when PDE III is already inhibited or when the myocardium is under beta-adrenoceptor-mediated stimulation.

1-Methyl-3-isobutylxanthine↗

PubMed1996

Sodium--potassium pump current in rabbit sino-atrial node cells.

1. The Na(+)-K+ pump current (Ip) was studied in sino-atrial (SA) node cells of rabbits using the whole-cell patch-clamp technique. 2. With 50 mM Na+ in the pipette solution ([Na+]pip), changing the external K+ concentration (-K+-o) from 0 to 5.4 mM caused the holding current to shift in an outward direction and reach a new steady state. The current-voltage relationships obtained by subtraction of current traces recorded at 0 mM Ko+ from those recorded at 5.4 mM Ko+ revealed time-independent and voltage-dependent characteristics. The external K(+)-induced current was completely blocked by external application of 10 microM ouabain, indicating the existence of Ip in SA node cells of rabbit heart. 3. Ip increased as [K+]o increased. With 30 mM Na+pip, Ip at 0 mV was activated by [K+]o with non-linear least-squares fit parameters for the Hill equation of K0.5 of 1.4 mM and a Hill coefficient (nH) of 1.2 (n = 7). 4. The cation dependence of the K+ site of the Na(+)-K+ pump was examined using various monovalent cations. The sequence was K+ > or = Rb+ > Cs+ > > > Li+. 5. Ip at 0 mV also increased as [Na+]pip was increased from 10 to 150 mM at 5.4 mM Ko+, with a K0.5 value of 14 mM and a nH of 1.3 (n = 54). 6. Ip at 0 mV was reduced by lowering the temperature from 37 to 25 degrees C with 30 mM Na+pip and 5.4 mM Ko+. The temperature coefficient (Q10) for Ip was 2.1 (n = 27). 7. With 10 mM Na+pip and 5.4 mM Ko+, the half-activation voltage of Ip was -52 +/- 16 mV and the current at this voltage was 22.5 +/- 3.5 pA (n = 10), indicating that Ip contributes significantly to the background outward current during the normal pacemaker potential of SA node cells.

Animals↗