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Hiroshi Tamai

Publications and source records attributed to Hiroshi Tamai.

At least 19 recordsLinked to original sources
PubMed2007

A case of nephrogenic diabetes insipidus with a novel missense mutation in the AVPR2 gene.

We describe a pediatric case of nephrogenic diabetes insipidus (NDI) with a novel missense mutation in the arginine vasopressin receptor 2 (AVPR2) gene. The patient, a 3-year-old boy, had polyuria (4357 ml/day, 7230 ml/m(2)/day) and polydipsia. Water deprivation testing demonstrated no decrease of urine volume, and urinary volume did not respond to subcutaneous injection of 0.1 U/kg pitressin. Molecular genetic analysis demonstrated that the patient had an AVPR2 missense mutation involving substitution of phenylalanine for tyrosine at position 205 (Y205F). It was also found that the patient's mother was heterozygous for this Y205F mutation. Analysis of the intermolecular interaction of the Tyr-205 hydrogen group by molecular modeling showed that Tyr-205 was located in transmembrane domain (TM) 5, and that its hydroxy group formed a hydrogen bond with Leu-169 main-chain =O located in TM 4. The mutation of Tyr-205 to phenylalanine would cause loss of this hydrogen bond and decrease or change the interaction between these TM coils, thus affecting the ability of AVP to bind to the receptor. According to this molecular model of AVPR2, the Y205F mutation would cause nephrogenic diabetes insipidus.

Base Sequence↗
PubMed2006

Effects of alpha tocopherol and probucol supplements on allergen-induced airway inflammation and hyperresponsiveness in a mouse model of allergic asthma.

OBJECTIVE: We investigated the role of antioxidants in airway hyperresponsiveness to acetylcholine using young asthma model mice, which were sensitized and stimulated with ovalbumin. METHODS: The mice had been fed either a normal diet, an alpha-tocopherol-supplemented diet or a probucol-supplemented diet 14 days before the first sensitization. They were immunized with antigen at intervals of 12 days and, starting from 10 days after the second immunization, they were exposed to antigen 3 times every 4th day using an ultrasonic nebulizer. Twenty-four hours after the last antigen inhalation, airway responsiveness to acetylcholine was measured and bronchoalveolar lavage fluid (BALF) was collected. A blood and lung tissue study was also carried out. RESULTS: Twenty-four hours after the last antigen challenge, both IL-4 and IL-5 in the BALF of alpha-tocopherol-supplemented mice were significantly decreased. The IL-5 level in probucol-supplemented mice was also decreased, but there was no difference in IL-4 levels. The serum IgE level was decreased in probucol-supplemented mice. Differential cell rates of the fluid revealed a significant decrease in eosinophils due to antioxidant supplementation. Airway hyperresponsiveness to acetylcholine was also repressed in antioxidant-supplemented mice. In histological sections of lung tissue, inflammatory cells and mucus secretion were markedly reduced in antioxidant-supplemented mice. We investigated the antioxidant effect on our model mice by examining 8-isoprostane in BALF and lung tissue, and acrolein in BALF; however, our experiment gave us no evidence of the antioxidant properties of either alpha-tocopherol or probucol contributing to the reduction of airway inflammation. CONCLUSION: These findings indicate that alpha-tocopherol and probucol suppress allergic responses in asthma model mice, although these two drugs cause suppression in different ways that are unrelated to antioxidation.

Acrolein↗
PubMed2006

Febrile seizures associated with influenza A.

To clarify the clinical impact of influenza A on the development of febrile seizures (FS), consecutive FS patients brought to our hospital between October 2003 and September 2004 were prospectively surveyed. Patients infected with influenza A (influenza A patients) and those uninfected with influenza (non-influenza patients) were compared with regard to clinical characteristics of FS. Influenza infection was determined by rapid antigen test and/or serologically. Associations of influenza A with atypical findings of FS, including partial seizures, prolonged seizures, multiple seizures during the same illness, and 30-min or longer prolonged postictal impairment of consciousness (PPIC), were analyzed by multiple logistic regression. A total of 215 patients (47 influenza A and 168 non-influenza patients) were enrolled in the study. Age was significantly higher in the influenza A group (39.85+/-22.16 months vs. 27.51+/-17.14 months, P<0.001). Of 42 patients aged 48 months or older, which corresponded to the 80th percentile for age, 15 (35.7%) were influenza A patients, with a significantly higher incidence of such patients than in the subgroup of patients aged 47 months or younger (32/173, 18.5%) (P=0.015). On multiple logistic regression analysis, influenza A was independently associated with PPIC (odds ratio: 4.44, 95% confidence interval: 1.52-12.95, P=0.006), but not with other atypical findings. The positive association of influenza A with PPIC suggests that influenza may affect state of consciousness at the same time that it induces seizures with fever.

Age Distribution↗
PubMed2006

Classification of benign infantile afebrile seizures.

PURPOSE: The aim of this study is to classify infantile cases with benign seizures into known epileptic syndromes, thereby facilitating discussion of clinical factors that could play an important role in diagnosis. SUBJECTS: Fifty-seven patients with afebrile seizures fulfilling all of the following criteria were enrolled: (1) normal development prior to the onset, (2) no underlying disorders nor neurological abnormalities, (3) onset before the age of four and (4) normal interictal EEG and neuroimaging findings. RESULTS: Thirty-nine cases (Group A) were characterized by an association of mild gastroenteritis. The remaining 18 cases were divided into two groups according to the seizure type. One group had partial seizures (Group B, 13 cases) while the other was suspected to have generalized seizures (Group C, 5 cases). Age at onset was significantly higher for Group A (19.5 +/- 5.5 months) than Groups B (5.3 +/- 1.8 months) (p<0.001) and C (5.8 +/- 3.5 months) (p=0.038). Positive family history of seizure disorder, seizure cluster tendency, and the efficacy of lidocaine against seizure clusters were common in the three groups. CONCLUSIONS: Features in Group A were consistent with benign convulsions with mild gastroenteritis (proposed by Morooka) [Morooka, K., 1982. Mild diarrhea and convulsions. Shonika 23, 134-137 (in Japanese)], those of Group B with benign partial epilepsy in infancy [Watanabe, K., Yamamoto, N., Negoro, T., Takaesu, E., Aso, K., Furune, S., Takahashi, I., 1987. Benign complex partial epilepsies in infancy. Pediatr. Neurol. 3, 208-211], and those of Group C with benign infantile convulsions [Fukuyama, Y., 1963. Borderland of epilepsy with special reference to febrile convulsions and so-called infantile convulsions. Seishin Igaku 5, 211-223 (in Japanese)]. The distinction between these syndromes depends upon age at onset, association with gastroenteritis, and ictal symptomatology. In our experience, however, it was not easy to catch seizure type accurately in clinical situations. As far as the results of ictal video-EEG monitoring ever carried out concern, focal initiation of parxysmal discharges was demonstrated in all cases, not only of BPEI but also of apparent generalized seizures examined without exception. These observations led the authors to conclude that the identity of BIC is dubious, most probably it will represent a subtype of BPEI.

Age of Onset↗
PubMed2006

Molecular cloning of the rat beta-carotene 15,15'-monooxygenase gene and its regulation by retinoic acid.

BACKGROUND: beta-Carotene exhibits biological activity as provitamin A. Key step in vitamin A formation is the cleavage of beta-carotene to retinal by an enzyme designated as beta-carotene 15,15'-monooxygenase (BCM). Recently, it is reported that expression of BCM gene in the intestine is under feedback regulation by retinoic acid (RA). However, the regulation of BCM gene expression in various other tissues is still unknown. AIM OF THE STUDY: In the present study, we identified the full-length cDNA encoding the rat BCM gene and investigated the regulation of its expression in several tissues by RA in the presence of vitamin A deficiency. METHODS: We cloned the full-length cDNA encoding BCM gene from a rat intestinal cDNA library by hybridization screening. The BCM gene expression was examined using Northern blotting and reverse transcription-PCR analysis. We also investigated whether BCM gene expression was regulated by retinoids in several tissues of vitamin A-deficient rats. RESULTS: Sequence analysis of this clone revealed an open reading frame of 1,701 bases encoding a protein of 566 amino acids. The predicted polypeptide showed 94%, 81%, and 66% identity with mouse, human, and chicken BCM, respectively. Rat BCM mRNA was highly expressed in the intestine and liver, while there was weak expression in the testes, kidneys, and lungs. Immunoblotting revealed that rat BCM is a 64-kDa protein. BCM gene expression was increased in the small intestine by vitamin A deficiency compared with that in rats on a control diet, while this upregulation was suppressed by all-trans RA (ATRA) or 9-cis RA (9-cis RA). BCM gene expression in the lungs and testes was also suppressed by ATRA or 9-cis RA in rats with vitamin A deficiency. However, hepatic BCM gene expression was only decreased by ATRA and renal expression was not affected by either retinoid. As the small intestine is the major site of beta-carotene conversion, intestinal BCM gene expression may be more tightly regulated. CONCLUSION: These data suggest that BCM gene expression in several tissues may be down-regulated by RA at the level of conversion of beta-carotene to retinal. To prevent an excess of retinol, homeostasis may occur at the level of conversion of beta-carotene to retinal in several tissues.

Amino Acid Sequence↗
PubMed2006

Role of chymase-dependent angiotensin II formation in monocrotaline-induced pulmonary hypertensive rats.

Angiotensin II-forming chymase is expressed in the pulmonary arteries of the monocrotaline-induced pulmonary hypertensive rats, but its actual role is unclear. We studied chymase-dependent angiotensin II formation in the pulmonary arteries of the monocrotaline-induced pulmonary hypertensive rats and observed the effects of an angiotensin II receptor blocker on vascular remodeling. Four weeks after the administration of monocrotaline (60 mg/kg, s.q.), echocardiographic, hemodynamic, morphometric and biochemical analyses were performed. Age-matched rats were used as controls. To evaluate the effects of an angiotensin II receptor blocker, 2 wk after beginning of monocrotaline treatment, the rats were given candesartan (10 mg/kg per day) or placebo for 2 wk. In the monocrotaline-induced pulmonary hypertensive rats, the elevated systolic pulmonary arterial pressure and right ventricular hypertrophy were observed. Medial hypertrophy of lung arterioles was also observed. Chymase activity and angiotensin II concentration, but not angiotensin-converting enzyme activity, were significantly increased in the lung. In the angiotensin II receptor blocker-treated group, both systolic pulmonary arterial pressure and right ventricular hypertrophy were significantly reduced, and arteriolar hypertrophy was also prevented. Thus, angiotensin II-forming chymase may play a role in the proliferation of the medial layer in the lung arterioles of monocrotaline-induced pulmonary hypertensive rats.

Angiotensin II↗
PubMed2006

Two cases of hyponatremic-hypertensive syndrome in childhood with renovascular hypertension.

UNLABELLED: We report two children with renovascular hypertension and fibromuscular dysplasia. They initially presented with severe hyponatremia, hypokalemia, polyuria, and transient proteinuria. This combination of symptoms is known to occur in patients with renovascular and malignant hypertension, and is known as hyponatremic-hypertensive syndrome (HHS), although it is considered rare in children. Since in both of our patients, the renal arterial stenosis was very severely or almost totally occlusive, we could not perform percutaneous transluminal renal artery angioplasty, and therefore nephrectomy was the only option. A histological study showed partial or complete occlusion with intimal hyperplasia and medial fibroplasia of intrarenal arteries such as the interlobular arteries. CONCLUSION: Both patients showed rapidly progressive renovascular hypertension and loss of function of the affected kidney. In order to preserve renal function in such cases, early invasive intervention appears to be necessary.

Child, Preschool↗
PubMed2006

Neurodevelopmental outcome of infants with birth asphyxia treated with magnesium sulfate.

BACKGROUND: A neuroprotective effect of MgSO(4) has been shown in some animal models of perinatal hypoxic-ischemic brain damage. The aim of the present paper was to determine whether postnatal MgSO(4) infusion (250 mg/kg per day i.v. for 3 days, in combination with dopamine) is safe in infants with severe birth asphyxia, and also observe effects on neurodevelopmental outcome at 18 months. METHODS: Inclusion criteria were clinical history consistent with perinatal asphyxia; gestational age at least 37 weeks; 5 min Apgar score < or =6; failure to initiate spontaneous respiration within 10 min after birth; and symptoms of encephalopathy. On each day MgSO(4) was infused over 1 h in combination with dopamine (5 microg/kg per min). Changes in vital signs, clinical course of encephalopathy, laboratory variables, and adverse events were monitored. Infants were followed for 18 months. RESULTS: Thirty infants were studied. Mean birthweight was 2878 g; mean gestational age, 39.6 weeks, and median 5 min Apgar score, 3. All required endotracheal intubation for resuscitation. Median age at MgSO(4) initiation was 5 h. All infants had moderate or severe hypoxic-ischemic encephalopathy. Mean serum Mg(2+) concentration remained at least 1.3 mmol/L. MgSO(4) caused no change in physiological variables including mean arterial pressure. Two infants died as neonates, while six of 28 survivors had severe neurodevelopmental disability at 18 months; the remaining 22 had no neurodevelopmental disability. CONCLUSION: Postnatal infusion of MgSO(4) with dopamine caused no change in physiological variables. Deaths and severe sequelae were less frequent than in reported cases with the same grade of hypoxic-ischemic encephalopathy severity, and this treatment may improve neurodevelopmental outcome in infants with severe birth asphyxia.

Asphyxia Neonatorum↗
PubMed2006

[Case of Sanfilippo syndrome type B and Wilson disease born to unrelated parents].

A 5-year-old boy visited a hospital because of macrocephalus, mental retardation and hepatic dysfunction, and was suspected to have Wilson's disease since his father had this disease. The serum level of ceruloplasmin was low, but urinary copper excretion was not increased markedly. He was treated with D-penicillamine. He was then reffered to our hospital because of his facial features suggesting mucopolysaccharidosis. Based on mucopolysacchariduria and the deficiency of N-acetylglucosaminidase, the diagnosis of Sanfilippo syndrome type B was made. Molecular analyses identified him as a compound heterozygote for both the ATP7B (A844V/2659delG) and alpha-N-acetylglucosaminidase (V241M/R482W) genes, responsible for Wilson's disease and Sanfilippo syndrome type B, respectively. Although born to non-consanguineous parents, he had two rare autosomal recessive diseases. In this case, liver dysfunction was attributed to Wilson's disease, and mental retardation to Sanfilippo syndrome.

Acetylglucosaminidase↗
PubMed2006

[Changes of electroencephalographic findings in a case of migraine with various neurological symptoms].

We report here an 1-year-old boy who was diagnosed as sporadic hemiplegic migraine demonstrated transient changes in electroencephalographic (EEG) background activity accompanied with migraine attacks. The attacks were associated with various neurological complications such as impairment of consciousness and hemiplegia and so on, which coincided with the changes of EEG findings. When his first headache developed with fever and impairment of consciousness, diffuse slow waves (1-2 Hz, 250-300 microV) appeared transiently. The slow wave gradually improved thereafter, and disappeared on the 24th day. On the 25th day, when he had the second attack with left hemiplegia and impairment of consciousness and sensation, slow waves, (2-3 Hz, 250-300 microV) appeared on right side of the brain. Constriction of the right middle cerebral artery was found on MR angiography at that time. The EEG change had improved to normal background activity 3 days after the episode. This unique case demonstrated that transient EEG changes seem to be correlated with the existence of unconsciousness and the laterality of the ischemic insult. We may assume that the changes of electroencephalographic findings may represent the cortical dysfunction caused by vascular constriction.

Cerebral Cortex↗
PubMed2006

[Nephrocalcinosis due to renal tubular acidosis in two brothers].

A 25-year-old man was admitted to our hospital because of left lumbago. An abdominal X-ray film demonstrated multiple calculi in the medullary positions of both kidneys and an impacted calculus in the left ureter. He was diagnosed with bilateral nephrocalcinosis and nerve deafness due to distal renal tubular acidosis (RTA) in childhood and was treated with alkali agents for several years. Extracorporeal shock wave lithotripsy was performed successfully against the left ureteral calculus. His older brother had also been diagnosed with RTA and nephrocalcinosis at the age of 2 years and 6 months. Nephrocalcinosis due to RTA associated with nerve deafness in brothers is rarely reported.

Acidosis, Renal Tubular↗
PubMed2006

[Saccadic eye movements in children with reading disorders].

Several reports raised the possibility that dysfunction of saccadic eye movements produces reading disorder (RD), although opposite conclusions have also been reported. In this study, saccadic eye movements were investigated in 13 forth graders with RD and 20 age-matched controls during reading and non-reading tasks. Compared to the control group, children with RD showed significantly higher incidences of both forward and backward saccadic eye movements in reading tasks, while they revealed a significantly lower number of saccadic eye movements in response to sequentially moving targets in two types of non-reading tasks. These problems, seen in non-reading tasks, suggest that excessive saccadic eye movements observed in RD children during reading are not produced by mechanisms involved in the language and phonological processes alone, but also those in the saccadic eye movement process. Dysfunction in the saccadic eye movements could be one of the causal factors that produce RD.

Child↗
PubMed2005

The effect of vitamin K2 on bone metabolism in aged female rats.

Reactive oxygen species (ROS) may contribute to aging and osteoporosis resulting from marked decreases in plasma antioxidants in aged osteoporotic women. On the other hand, high-dose vitamin K2 (menaquinone-4: menatrenone, MK-4) supplementation has been reported to reduce ovariectomy-induced bone loss in rats and to decrease osteoporotic fracture in postmenopausal women. However, the mechanism by which vitamin K2 prevents osteoporosis is unclear. Recently, vitamin K2 has been suggested to preserve antioxidant activity as a novel function. Therefore, we investigated the effect of vitamin K2 on the osteoporosis of aged rats by evaluating the relationships between serum antioxidant levels and bone metabolism. Aged female rats exhibited significantly lower serum alkaline phosphatase activity and osteocalcin level, together with lower serum levels of antioxidants such as 17beta-estradiol, macrophage migration inhibitory factor (MIF) and glutathione peroxidase (GPx) activity, as compared with young female rats. On the other hand, vitamin K2 supplementation (500 mg/kg, food intake) for 98 days led to a significantly increased serum vitamin K2 level (3,045+/-915 ng/ml in the vitamin K2 supplemented group vs. 4.6+/-3.4 ng/ml in the control diet group; P<0.0001) with increased serum alkaline phosphatase activity and MIF level (P<0.05). Unexpectedly, however, it failed to increase the serum level of antioxidants such as GPx. Nor did it affect bone metabolism markers such as osteocalcin and osteopontin, which were significantly lower than in the young female rats (P<0.05). Finally, the histomorphometric properties of the proximal tibia in the femur were not altered by vitamin K2. These results suggest that high-dose vitamin K2 supplementation neither improves lowered antioxidant levels nor stimulates bone formation in aged rats.

Age Factors↗
PubMed2005

Functional analysis of PTPN11/SHP-2 mutants identified in Noonan syndrome and childhood leukemia.

Noonan syndrome (NS) is characterized by short stature, characteristic facial features, and heart defects. Recently, missense mutations of PTPN11, the gene encoding protein tyrosine phosphatase (PTP) SHP-2, were identified in patients with NS. Further, somatic mutations in PTPN11 were detected in childhood leukemia. Recent studies showed that the phosphatase activities of five mutations identified in NS and juvenile myelomonocytic leukemia (JMML) were increased. However, the functional properties of the other mutations remain unidentified. In this study, in order to clarify the differences between the mutations identified in NS and leukemia, we examined the phosphatase activity of 14 mutants of SHP-2. We identified nine mutations, including a novel F71I mutation, in 16 of 41 NS patients and two mutations, including a novel G503V mutation, in three of 29 patients with leukemia. Immune complex phosphatase assays of individual mutants transfected in COS7 cells showed that ten mutants identified in NS and four mutants in leukemia showed 1.4-fold to 12.7-fold increased activation compared with wild-type SHP-2. These results suggest that the pathogenesis of NS and leukemia is associated with enhanced phosphatase activity of mutant SHP-2. A comparison of the phosphatase activity in each mutant and a review of previously reported cases showed that high phosphatase activity observed in mutations at codons 61, 71, 72, and 76 was significantly associated with leukemogenesis.

Adolescent↗
PubMed2005

Regulation of apoptosis by glutathione redox state in PC12 cells exposed simultaneously to iron and ascorbic acid.

We previously reported that the levels of non-protein-bound iron (NPBI) and ascorbic acid (AA) are markedly increased in the cerebrospinal fluid of infants with perinatal asphyxia. The present study showed that FeSO4 and AA synergistically induced apoptosis of PC12 cells, which was prevented by alpha-tocopherol and glutathione (GSH) ethyl ester. Markers of free radical damage, such as ortho-tyrosine, meta-tyrosine, and F(2alpha)-isoprostane, showed a gradual increase. AA and ferrous NPBI disappeared rapidly from the culture medium, but exposure for only a few hours was sufficient to trigger apoptosis. Intracellular GSH decreased progressively along with a concomitant increase of glutathione disulfide (GSSG). The baseline half-cell reduction potential (Ehc) for GSSG, 2H+/2GSH couple was -246 mV and an Ehc of -200 mV was the critical level to switch on apoptosis, although some cells escaped this fate by transient increase of intracellular GSH. Once Ehc reached around -165 mV (81 mV oxidation from the baseline), all cells lost the ability to maintain an adequate intracellular GSH level and subsequently underwent apoptosis. These findings at least partly explain the mechanism of Fe-AA cytotoxicity, in that ferrous iron catalyzes hydroxyl radical generation and induces lipid peroxidation, after which subsequent depletion of GSH raises Ehc to the critical level for triggering or potentiating the apoptotic cascade.

Animals↗
PubMed2005

Identification of apo- and holo-forms of ceruloplasmin in patients with Wilson's disease using native polyacrylamide gel electrophoresis.

OBJECTIVES: To determine the serum ratio of holo-ceruloplasmin to total ceruloplasmin in patients with Wilson's disease (WD), we identified apo- and holo-forms of serum ceruloplasmin with native-PAGE electrophoresis. DESIGN AND METHODS: Serum obtained from nine patients with Wilson's disease was subjected to native-PAGE analysis. We also determined the ceruloplasmin level and ferroxidase activity in all of the samples. RESULTS: Among the nine patients, three had both forms of ceruloplasmin and six had only apo-ceruloplasmin. In the patients who had only apo-ceruloplasmin, the serum ceruloplasmin level was significantly lower than in the patients with both forms. CONCLUSIONS: Differences in the ability to incorporate copper into ceruloplasmin may have a role in ceruloplasmin concentrations in patients with Wilson's disease.

Adolescent↗