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Biomedical subjects

N Iwasaki

Publications and source records attributed to N Iwasaki.

At least 19 recordsLinked to original sources
PubMed2006

Extracellular matrix modulates expression of cell-surface proteoglycan genes in fibroblasts.

Cell-surface proteoglycans are involved in many functions, including interactions with components of the extracellular microenvironment. They also act as coreceptors that bind and modify the actions of various growth factors, cytokines, and the extracellular matrix (ECM). This study investigated the regulation by the ECM of the expression of cell-surface proteoglycans (CD44, syndecan-1-4, betaglycan, glypican-1). We examined the changes in the expression levels of cell-surface proteoglycan genes in intact tendon, monolayer culture, and under various culture conditions. There was a significant increase in the expression of CD44 and syndecan-4 mRNAs during cell isolation from the tendon. With the switch to a 3D culture environment, there was a significant increase in the expression of CD44 at each passage point relative to its expression in 2D at those passage points. Syndecan-4 mRNA also increased steadily at each passage point in 3D culture environment. This influence on cell surface proteoglycans gene expression may indicate that collagen gel culture mimics in vivo tendon environment. This study provides further insight into the regulation of cell-surface proteoglycans in ligament and tendon fibroblasts by the ECM and 3D culture conditions.

Animals↗
PubMed2005

[Delayed onset malignant hyperthermia after a closure of ventricular septal defect].

An 18 month-old girl was diagnosed as ventricular septal defect (VSD) with mild aortic valve prolapse. She underwent a closure of VSD. Intra-and early postoperative course was uneventful. However, 20 hours after surgery, sudden bradycardia led to cardiac arrest and strong muscle rigidity was seen. Hyperkalemia and metabolic acidosis rapidly progressed and resuscitation was failed. Extracorporeal life support and continuous hemodialysis were initiated, but the patient died with multiple organ failure on 5th postoperative day. Her clinical course supported the diagnosis of delayed onset malignant hyperthermia. Histopathological findings of muscle biopsy were consistent with rhabdomyolysis, and immunopathological stains demonstrated changes as in a Duchenne type muscular dystrophy carrier. Delayed onset malignant hyperthermia is an extremely rare complication of general anesthesia. We should be aware of this lethal condition, which occurs with a certain time lag after surgery, especially when the patient has possible background of myopathy.

Female↗
PubMed2004

Linkage and association of febrile seizures to the IMPA2 gene on human chromosome 18.

BACKGROUND: Febrile seizures (FSs) are the most common form of childhood seizures, and genetic factors play a role in susceptibility to FS. OBJECTIVE: To identify novel loci and genes associated with susceptibility to FS. METHODS: Study participants were the FS probands and family members of 59 Japanese nuclear families (223 members including 112 affected children). Forty-eight of these families had at least two affected children for which genome-wide linkage screening was carried out. The Genehunter software was used to perform nonparametric multipoint linkage analysis. Mutational and association analyses were conducted in all 59 Japanese FS families. RESULTS: Genotyping data of 407 microsatellite markers suggested linkage of FSs to chromosome 18p11.2 (non-parametric linkage score = 3.68, p = 0.0001). This region includes the IMPA2 gene, which encodes myo-inositol monophosphatase (IMPase) 2. In the phosphatidylinositol-signaling pathway, IMPase is inhibited by lithium, which has a proconvulsant effect, and is stimulated by carbamazepine, an anticonvulsant. A systematic search was performed for mutations in IMPA2 in 24 unrelated randomly selected Japanese FS patients; seven variants were detected. Haplotype analysis revealed an association of a common haplotype in IMPA2 with FSs (p = 0.0009). CONCLUSION: The authors found a novel locus on chromosome 18p11.2 for febrile seizures (FSs). IMPA2 is likely to be an FS susceptibility gene.

Bipolar Disorder↗
PubMed2004

The evaluation of autonomic nervous function in a patient with hereditary sensory and autonomic neuropathy type IV with novel mutations of the TRKA gene.

We report on a 10-year-old girl with anhidrosis and insensibility to pain, but no severe mental retardation or self-mutilation, diagnosed as hereditary sensory and autonomic neuropathy type IV (HSAN IV). Genetic analysis of her TRKA gene, which is responsible for HSAN IV, revealed two novel missense mutations in the tyrosine kinase domain. Cardiovascular autonomic nervous system function tests showed normal muscle sympathetic nerve activity associated with arterial baroreflex, reduced skin sympathetic nerve activity in the second and fifth fingers and palms, and abnormal circadian rhythm of cardiovascular autonomic nervous system. These findings have never before been reported in HSAN IV and may provide a clue to the neurological pathophysiology of this disease.

Autonomic Nervous System↗
PubMed2003

Notable diversity in hemoglobin expression patterns among species of the deep-sea clam, Calyptogena.

The deep-sea clams Calyptogena nautilei and C. tsubasa, which live in the cold-seep area at a depth of 3570 m in the Nankai Trough, Japan, have abundant hemoglobins (Hbs) in erythrocytes, similar to other Calyptogena species. We determined the cDNA-derived amino acid sequences of Hbs from two Calyptogena species. C. tsubasa was found to contain two dimeric Hbs, Hb I consisting of 145 amino acid residues and Hb II with 137 residues, similar to known Hbs from C. soyoae and C. kaikoi. Sequence identity was over 90% among the orthologous chains of Calyptogena Hbs. On the other hand, surprisingly, C. nautilei contained two monomeric Hbs, Hb III containing 141 residues and Hb IV with 134 residues. In addition, Hbs III and IV showed only 33-42% sequence identity with Hbs I and II from other Calyptogena species. The distal (E7) histidine, one of the functionally important residues of the heme protein, is replaced by glutamine in all Hb chains of Calyptogena species. A phylogenetic analysis indicated that C. nautilei Hb III is closer to Hb I from other Calyptogena species. We suppose that a Hb gene was duplicated at least three times in an immediate ancestor of Calyptogena and, presumably depending on physiological conditions different Hb sets are being expressed: dimeric Hbs I and II in C. soyoae, C. kaikoi and C. tsubasa, and monomeric Hbs III and IV in C. nautilei.

Amino Acid Sequence↗
PubMed2003

Mutation analysis of the leucine-rich, glioma inactivated 1 gene (LGI1) in Japanese febrile seizure patients.

Mutations in the leucine-rich, glioma inactivated 1 gene (LGI1) were recently identified in some families with autosomal dominant lateral temporal epilepsy (ADLTE). To investigate whether the LGI1 gene is a susceptibility gene for febrile seizures (FS), we performed a systematic search for mutations in 94 unrelated Japanese patients with FS. We detected two intronic polymorphisms (IVS2 + 19 A/G and IVS6 - 18 T/C). No non-synonymous mutation was detected. We genotyped these polymorphisms and performed a case-control study and transmission disequilibrium testing (TDT) of 62 FS families (n = 230) and 105 control subjects. None of the polymorphisms was significantly associated with FS. Our results indicate that genomic variations in the LGI1 gene are not likely to be substantially involved in the etiology of FS in the Japanese population.

Alleles↗
PubMed2002

Radial osteotomy for late-stage Kienböck's disease. Wedge osteotomy versus radial shortening.

We have reviewed 20 patients with stage-IIIB and stage-IV Kienböck's disease in order to examine the efficacy of two forms of radial osteotomy, namely radial wedge osteotomy and radial shortening. Lateral closing wedge osteotomies and radial shortenings were carried out on 11 and nine patients, respectively. There were no preoperative differences with respect to age, gender, and radiological stage. After a mean follow-up of 29 months, all patients, in both groups, had either a good or an excellent outcome. After the lateral closing wedge osteotomy, the radioscaphoid angle significantly increased and the Ståhl index significantly decreased. Progression of the degenerative changes at the radioscaphoid joint was found in two patients in this group. By contrast, there were no significant changes in any radiological parameters after radial shortening. Both procedures gave acceptable clinical results in stage-IIIB and stage-IV Kienböck's disease.

Adolescent↗
PubMed2001

Prevalence of A-to-G mutation at nucleotide 3243 of the mitochondrial tRNA(Leu(UUR)) gene in Japanese patients with diabetes mellitus and end stage renal disease.

The A-to-G mutation at nucleotide 3243 of the mitochondrial tRNA(Leu(UUR)) gene (mt.3243A>G) is associated with both diabetes mellitus and myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS). Recently, this mutation was found in three diabetic subjects with progressive kidney disease, suggesting that it may be a contributing factor in the development of kidney disease in patients with diabetes. The aim of this study was to evaluate the contribution of this mutation to the development of end stage renal disease (ESRD) in patients with diabetes. The study group consisted of 135 patients with diabetes and ESRD. The control group consisted of 92 non-diabetic subjects with ESRD who were receiving hemodialysis. The mt.3243A>G mutation was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). We found the mt.3243A>G mutation in eight patients (8/135; 5.9%), all of whom were initially diagnosed with type II diabetes. Five of the eight patients were subsequently also diagnosed with MELAS. We did not find the mutation in any of the 92 nondiabetic subjects with ESRD. The prevalence of this mutation was 6.5-fold higher in patients with diabetes and ESRD than in those with diabetes alone (8/135 vs 5/550, respectively; chi2 = 13.704; P = 0.0002). The mt.3243A>G mutation may be a contributing genetic factor in the development of ESRD in Japanese patients with diabetes.

Adult↗
PubMed2001

Identification of three missense mutations in the peroxisome proliferator-activated receptor alpha gene in Japanese subjects with maturity-onset diabetes of the young.

We screened the protein-coding region of the peroxisome proliferator-activated receptor alpha gene (PPARA) and the flanking intron sequences for mutations in 57 unrelated Japanese subjects with maturity-onset diabetes of the young (MODY). We found three missense mutations, designated P22R, D140Y, and V227A. The D140Y and V227A mutations were found at similar frequencies in MODY and in nondiabetic Japanese subjects, suggesting that they were unlikely to be pathogenic. The P22R mutation was found in a single female subject with MODY. Two of her four siblings, all of whom were diagnosed with diabetes before age 35 years, also inherited the P22R mutation. However, two other diabetic siblings had not inherited the mutant allele, implying that the P22R mutation was not the cause of MODY in this family. Variation in the coding region of PPARA is unlikely to be a major cause of MODY in Japanese people.

Adult↗
PubMed2001

Normal hip joint contact pressure distribution in single-leg standing--effect of gender and anatomic parameters.

A practical and easy-to-use analysis technique that can study the patient's hip joint contact force/pressure distribution would be useful to assess the effect of abnormal biomechanical conditions and anatomical deformities on joint contact stress for treatment planning purpose. This technique can also help to establish the normative database on hip joint contact pressure distribution in men and women in different age groups. Twelve anatomic parameters and seven biomechanical parameters of the hip joint in a normal population (41 females, 15 males) were calculated. The inter-parameter correlations were investigated. The pressure distribution in the hip joint was calculated using a three-dimensional discrete element analysis (DEA) technique. The 3D contact geometry of the hip joint was estimated from a 2D radiograph by assuming that the femoral head and the acetabular surface were spherical in shape. The head-trochanter ratio (HT), femoral head radius, pelvic height, the joint contact area, the normalized peak contact pressure, abductor force, and the joint contact force were significantly different between men and women. The normalized peak contact pressure was correlated both with acetabular coverage and head-trochanter ratio. Change of abductor force direction within normal variation did not affect the joint peak contact pressure. However, in simulated dysplastic conditions when the CE angle is small or negative, abductor muscle direction becomes very sensitive in joint contact pressure estimation. The models and the results presented can be used as the reference base in computer simulation for preoperative planning in pelvic or femoral osteotomy.

Adult↗
PubMed2001

Postprandial middle cerebral arterial vasoconstriction in cirrhotic patients. A placebo, controlled evaluation.

BACKGROUND/AIMS: The objective of this study was to determine whether cerebral arterial vasoconstriction occurs in relation to postprandial splanchnic blood pooling in cirrhotic patients. METHODS: The pulsatility and the resistive indexes and blood flow in the middle cerebral artery were measured by magnetic resonance imaging in 21 cirrhotics and 14 controls. These measurements were repeated 30 min after ingestion of a 400 kcal liquid meal or placebo. Seven controls and 14 patients received the meal, and seven controls and seven patients received placebo. RESULTS: In the fasting conditions, cirrhotics had a greater pulsatility index (0.81 +/- 0.10 vs. 0.67 +/- 0.05, P < 0.001) and a greater resistive index (0.61 +/- 0.04 vs. 0.53 +/- 0.04, P < 0.001) and a lower blood flow (127 +/- 42 ml/min vs. 167 +/- 37 ml/min, P < 0.03) in the middle cerebral artery compared with controls. Meal ingestion significantly increased the pulsatility index (P < 0.03) and the resistive index (P < 0.01) and decreased blood flow (P < 0.03) in the middle cerebral artery in cirrhotics but not in controls. In contrast, placebo ingestion had no effect on the hemodynamic parameters in the middle cerebral artery in the two groups. CONCLUSIONS: Results support the hypothesis that middle cerebral arterial vasoconstriction seen in cirrhotic patients is one of the cerebral artery's homeostatic responses to underfilling of the splanchnic arterial circulation.

Adult↗
PubMed2001

Effects of major histocompatibility complex matching on graft survival in allogeneic rat limb transplantation.

Differences in the major histocompatibility complex (MHC) between recipients and donors present a problem because of immunologic responses in graft rejection. The purpose of this study is to clarify the efficacy of MHC matching against acute graft rejection of allogeneic limb transplants in rats. Right hindlimb transplantations were performed using various MHC-mismatched pairs of inbred rats. The rats were classified into 5 groups according to the differences in subregions of the RT1 (rat MHC) between the recipient and the donor: group 1, RT1-A,B,D barrier (the differences of RT1-A,B,D subregions); group 2, RT1-A barrier; group 3, RT1-B,D barrier; group 4, RT1-B barrier; and group 5, RT1-D barrier. The mean survival time significantly decreased in group 1 and increased in group 4. The results suggest that MHC matching clearly improves survival of transplanted limbs. Specifically, both RT1-A and D matching is the most effective compatibility in prolonging survival time of allogeneic limb transplants in rats.

Animals↗