Search PubMed⌕ Search

Biomedical subjects

T Iizuka

Publications and source records attributed to T Iizuka.

At least 73 records · Page 4Linked to original sources
PubMed2000

Prolonged mandibular hypomobility patient with a "square mandible" configuration with coronoid process and angle hyperplasia.

The objective of this study was the surgical management of chronic severe mandibular hypomobility patients associated with square mandible morphology with coronoid process and angle hyperplasia, and one-year follow-up data is reported. Ten patients were studied. All patients were female and had a history of gradual severe jaw hypomobility. Clinical findings were similar to those of a "closed lock" patient. However, the facial appearance in these patients showed a characteristic square mandible facial configuration. Coronoid process thickening and overgrowth of the mandibular angle was evident in the radiographic findings. Diagnostic imaging scarcely depicted any disk derangement, but a severely limited jaw opening was noted in spite of acceptable excursive jaw movements. Bilateral coronoidotomy or coronoidectomy was done initially, and then masseter muscle stripping via the intraoral approach. After successful reduction of jaw hypomobility, a selective mandibular anglectomy was completed. Physical therapy began within three to five days after the surgery. Postoperatively, all patients were questioned about their jaw function and their subjective assessment of the treatment. Interincisal jaw opening was recorded with a ruler marked in millimeters. Bilateral coronoidotomy or coronoidectomy and masseter muscle stripping were done for all patients; the mandibular anglectomy was performed in seven of the cases at 13 sites. Simultaneous TMJ surgery was done on three joints for three patients. Most patients reported improvement of jaw function, and the patients' subjective assessment revealed an average satisfaction rate of 74.6%. A preoperative mean jaw opening distance of 25.6 mm increased to 36.6 mm postoperatively at a one-year follow-up (p < 0.05). The conclusion was that surgical intervention is indicated when nonsurgical treatment is unsuccessful. Etiology is unknown, but masseter and temporal muscle contracture associated with mandibular coronoid and angle hyperplasia may be a strong component of the pathophysiology.

Adolescent↗
PubMed2000

The effect of blood supply in muscle and an elevated muscle flap on endogenous tissue-engineered bone by rhBMP-2 in the rat.

Metabolism and remodeling of bony tissue are maintained and controlled by blood supply. In this study, bony tissue osteoinduced heterotopically by recombinant human bone morphogenetic protein-2 (rhBMP-2) in rat muscles with different amounts of blood supply was investigated. The implant beds were in the latissimus dorsi muscle (LDM) and in the space wrapped with an elevated latissimus dorsi muscle flap (LDMF). The blood flow was preestimated at two muscle sites using a laser Doppler blood flowmeter. The flow value of the LDM was 2.23 +/- 0.17 ml/min/100 g (mean +/- standard deviation). The flow values of the LDMF were 1.71 +/- 0.22 ml/min/100 g 30 minutes after elevating the LDMF, 1.75 +/- 0.20 ml/min/100 g after 1 week, 1.83 +/- 0.19 ml/min/100 g after 2 weeks, and 1.99 +/- 0.18 ml/min/100 g after 3 weeks. Bony tissues induced heterotopically by rhBMP-2 were examined radiographically and histologically. On radiographs, radiopaque shadows in the LDM were almost as large as those in the LDMF. The radiopacity in the LDM was a little higher than that of the LDMF. The microscopic findings showed increased trabeculae and more hematopoietic marrow in the LDM than lamellalike bone in the LDMF. Mean bony area in the implant was 1.05 +/- 0.26 mm2 in the LDM, and was 0.70 +/- 0.11 mm2 in the LDMF. Bony proportions in the overall implant area were 18.3 +/- 3.46% in the LDF and 12.1 +/- 2.18% in the LDMF. The current study indicates that blood supply is an important factor for promoting heterotopic osteoinduction by rhBMP-2 to produce massive bony tissue as an endogenous method of tissue engineering.

Animals↗
PubMed2000

Osteogenesis by recombinant human bone morphogenetic protein-2 at skeletal sites.

Osteogenesis was evaluated in the mandibular bone by combinations of various dosages of recombinant human bone morphogenetic protein-2, atelopeptide Type I collagen, and porous hydroxyapatite (four groups: Group I, 2 micrograms recombinant human bone morphogenetic protein-2, atelopeptide Type I collagen, and porous hydroxyapatite; Group II, 10 micrograms recombinant human bone morphogenetic protein-2, atelopeptide Type I collagen, and porous hydroxyapatite; Group III, 50 micrograms recombinant human bone morphogenetic protein-2, atelopeptide Type I collagen, and porous hydroxyapatite; Control Group, only atelopeptide Type I collagen and porous hydroxyapatite). The prepared materials were implanted in the mandibular bone hole (7 mm in diameter, 2 mm deep). Three weeks later, the alkaline phosphatase activity in the implanted region was determined, and the histologic features of the excised tissue were examined. There were significant differences in histologic and biochemical findings among the four groups. In the recombinant human bone morphogenetic protein-2 implanted groups, osteogenesis increased with the dosage of recombinant human bone morphogenetic protein-2, as assessed by alkaline phosphatase activity and histologic findings. The results suggest that atelopeptide Type I collagen is an effective carrier for recombinant human bone morphogenetic protein-2 and that porous hydroxyapatite would be advantageous for clinical application as a material to maintain its original form after implantation.

Alkaline Phosphatase↗
PubMed2000

Corrections to coupled mode theory for deep gratings

We generalize the standard coupled mode equations describing interactions between forward and backward propagating waves in a nonlinear optical Bragg grating. Including the lowest order corrections of the grating depth, we obtain a Hamiltonian system that can be regarded as an extension of the usual coupled mode equations for shallow gratings. The results are consistent with existing results based on a Bloch wave expansion. We also obtain exact traveling solitary wave solutions, that can be regarded as a generalized gap soliton, modified by the grating's depth.

Journal Article↗
PubMed2000

Gap solitons in quadratically nonlinear gratings: beyond the cascading limit

We consider pulse propagation in quadratically nonlinear gratings. Assuming that the phase mismatch between the fundamental and the second-harmonic frequencies deltak is large, we present a perturbation method in deltak(-1). In the well known cascading limit, terms to deltak(-1) are kept; here we keep terms to deltak(-2), which leads to another type of coupled mode equations. Numerical calculation of the full equations support our theoretical results.

Journal Article↗
PubMed2000

Cortical potentials associated with voluntary mandibular movements.

Movement-related cortical potentials (MRCPs) are negative potentials over the scalp, which gradually increase prior to voluntary movements, and might be applied to elucidate the cortical efferent function of the mandibular movements. We compared the MRCPs accompanying various mandibular movements to study the motor control mechanism underlying these movements. Electroencephalograms (EEGs) were recorded from 11 electrodes placed over the scalp (F3, Fz, F4, T3, C3, Cz, C4, T4, P3, Pz, and P4), according to the International 10-20 System, and electromyograms (EMGs) were obtained from surface electrodes over the masseter muscle and the anterior belly of the digastric muscle. Ten healthy subjects were requested to make brisk and self-paced mandibular movements in 4 different directions (mouth-opening and -closing, and left and right lateral movements). We obtained MRCPs by averaging the EEG, using the visually determined EMG onset as a trigger signal. In all the movements, a slowly increasing, bilaterally widespread negativity starting 1.5 to 2.0 sec before the EMG onset (Bereitschaftspotential, or BP proper) was observed, with the maximum over the vertex region. The negative slope (NS') occurred about 300 to 700 msec before the EMG onset. The cortical maps of BP/NS' (BP and NS' combined), immediately prior to the mouth-opening and closing, showed a symmetrical distribution, whereas that for the lateral movements showed a tendency of predominance over the hemisphere ipsilateral to the direction of the movement. BP/NS' amplitudes at the onset of movement differed significantly or tended to do so between open, close, and lateral movements, suggesting that MRCP recordings may thus provide a means to explore the role of the cerebral cortex in the control of mandibular movements.

Adult↗
PubMed2000

Serum itraconazole and hydroxyitraconazole concentrations and interaction with digoxin in a case of chronic hypertrophic pachymenigitis caused by Aspergillus flavus.

A patient treated with itraconazole (ITCZ) under the diagnosis of Aspergillus flavus-induced chronic hypertrophic pachymeningitis is presented. The reason for the successful cure of this patient was investigated by the pharmacokinetic analysis of serum levels of ITCZ. Concurrently administered digoxin was also investigated for its drug-drug interaction. The patient (a 75-year-old male) developed ophthalmopathy, and was diagnosed as having A. flavus hypertrophic pachymeningitis by pachymeninx biopsy. After admission, he was treated with FLCZ, AMPH, 5-FC and MCZ. The infection tended to subside with the AMPH administration. Since renal insufficiency was induced by AMPH and the other antifungal drugs were ineffective, daily administration of 200 mg of ITCZ was initiated, and the inflammatory signs and symptoms gradually subsided. The symptoms did not recur during the 36 months of itraconazole treatment after discharge, and it was concluded that ITCZ was effective for A. flavus hypertrophic pachymeningitis. Pharmacokinetic parameters of ITCZ and OH-ITCZ as follows: ITCZ: Cmax 93.2 ng/ml, T1/2 beta 11 hours, AUC0-24 999 ng.h/ml, OH-ITCZ: Cmax 159.4 ng/ml, T1/2 beta 16. 2 hours, AUC0-24 of 1391 ng.h/ml. Both ITCZ and OH-ITCZ reached steady states seven days after administration began. The ITCZ and OH-ITCZ levels in serum collected 36 months after the initiation of administration were 452.9 ng/ml and 1233.6 ng/ml, respectively. Cmax and AUC0-24 of ITCZ and OH-ITCZ on the second day were markedly lower than those in healthy adults reported by Oguchi et al., and hypoalbuminemia observed at administration on that day was considered the most probable cause. It was assumed that the most plausible reason for a successful cure even at a low dose of ITCZ was the increase of distribution to tissue by the increase of the unbound form. Digoxin was concurrently given to this patient at 0. 125 mg/day, but the blood digoxin level was not elevated. Consideration of the blood level of albumin is believed to be important for evaluating the blood concentration of ITCZ.

Aged↗
PubMed2000

Osteoinduction by recombinant human bone morphogenetic protein-2 at intramuscular, intermuscular, subcutaneous and intrafatty sites.

To compare the osteoinductive activity of recombinant human bone morphogenetic protein-2 (rhBMP-2) at various sites in rats, 5 microg of rhBMP-2 were implanted into various sites, using atelopeptide type-I collagen (CL) as a carrier (BMP groups). CL implantation was used as a control. Forty Wistar rats were divided into intramuscular, intermuscular, subcutaneous and intrafatty site groups (IrM, IeM, SC and IF, respectively). Bone formation was evaluated radiographically, histologically and biochemically 21 days after implantation. In the BMP groups, the alkaline phosphatase activity and calcium content at all sites were higher than those in the control groups. Among the BMP groups, the new bone formation was highest in the IrM and lowest in the IF radiographically, histologically and biochemically. Five microg of rhBMP-2, a relatively low dose, induced adequate new bone formation in all sites. The variations of osteoinductive activity of rhBMP-2 in various sites may be due to differences in the blood supply.

Adipose Tissue↗
PubMed2000

[A case of mediastinal pseudocyst with unusual cystic findings in computed tomography].

We report here a case of mediastinal pseudocyst with unusual CT findings. A 25-year-old woman was admitted to our hospital due to a chest abnormal shadow. She had a cystic mass which was located at anterior mediastinum and was adjacent to great vessels broadly without invasive findings. The intraoperative and histological findings revealed that the cystic mass was a pseudocyst which had been generated by the rupture of a thymic cyst to the mediastinum.

Adult↗
PubMed2000

[Hyperbaric oxygen as an adjunctive treatment for descending necrotizing mediastinitis: report of a case].

We report a case of 59-year-old man of descending necrotizing mediastinitis (DNM) secondary to peritonsillar abscess. A 59-year-old man with diabetes mellitus was admitted to a local hospital because of cervical swelling related to a peritonsillar abscess. Despite administration of antibiotics, swelling of the neck, dysphagia and dyspnea deteriorated. Therefore he was urgently undergone a tracheotomy and transferred to our hospital by an ambulance. The surgery consisted with neck and anterior mediastinal drainage through neck and cervical collar incision. Culture of drainage fluid showed clostridium difficile. On postoperative day 5, we started hyperbaric oxygen therapy (HBOT). After lavage and HBOT, the patient improved by degrees, and discharged on postoperative day 82. DNM is a rare but serious complication of otopharyngeal and deep neck infection that spreads down to the mediastinum through the cervical-facial planes. Its mortality rate remains high even with aggressive surgical drainage and appropriate antibiotics. Our patient was successfully treated with urgent surgical drainage, antibiotics and HBOT. HBOT might be of great value as an adjunctive management to control this fatal infection.

Anti-Bacterial Agents↗
PubMed2000

[Neurosarcoidosis].

Explore the source record for details and available documents.

Diagnosis, Differential↗
PubMed2000

Regeneration of the junctional epithelium and connective tissue after transplantation of detergent-processed allo-teeth.

The authors have developed a new artificial dental implant and evaluated it in a dog model in terms of its potential to produce: I) regeneration of junctional epithelium; II) regeneration and attachment of connective tissue. The implants were constructed from allo-teeth. We removed the cell components from the periodontal ligaments of these teeth with a detergent (1% TritonX-100); the remaining acellular periodontal ligament acted as an extracellular matrix upon which regeneration and attachment could proceed. We placed 10 of these implants in the just-extracted sites of three beagle dogs. We observed regeneration of both junctional epithelium and connective tissue at all implant sites after 3 months. The connective tissue was attached in all cases. Use of the acellular periodontal ligament as an extracellular matrix may facilitate regeneration of host periodontal ligament tissue, thus contributing to recovery of host immunological defense and long-term oral function.

Animals↗
PubMed1999

Expression of bone morphogenetic protein-2 via adenoviral vector in C2C12 myoblasts induces differentiation into the osteoblast lineage.

To examine the effectiveness of a gene transfer of bone morphogenetic protein (BMP)-2 into C2C12 myoblasts, we constructed a human BMP-2-expressing replication-deficient adenoviral vector, AxCAOBMP-2. C2C12 cells were infected in vitro with either this viral vector or an Escherichia coli LacZ gene-expressing control adenovirus vector. An efficient gene transfer to the C2C12 cells was confirmed with the LacZ gene-expressing vector by X-gal staining. Abundant BMP-2 expression in C2C12 cells infected with this viral vector was confirmed by immunofluorescence and Western blot analysis. C2C12 cells transferred with the BMP-2 gene by this vector produced alkaline phosphatase in the cells and also produced and secreted osteocalcin in the culture medium, demonstrating that a gene transfer of BMP-2 into C2C12 cells in vitro could convert these cells from myoblast to osteoblast lineage.

Adenoviridae↗
PubMed1999

Iron coordination structures of oxygen sensor FixL characterized by Fe K-edge extended x-ray absorption fine structure and resonance raman spectroscopy.

FixL is a heme-based O(2) sensor protein involved in a two-component system of a symbiotic bacterium. In the present study, the iron coordination structure in the heme domain of Rhizobium meliloti FixLT (RmFixLT, a soluble truncated FixL) was examined using Fe K-edge extended x-ray absorption fine structure (EXAFS) and resonance Raman spectroscopic techniques. In the EXAFS analyses, the interatomic distances and angles of the Fe-ligand bond and the iron displacement from the heme plane were obtained for RmFixLT in the Fe(2+), Fe(2+)O(2), Fe(2+)CO, Fe(3+), Fe(3+)F(-), and Fe(3+)CN(-) states. An apparent correlation was found between the heme-nitrogen (proximal His-194) distance in the heme domain and the phosphorylation activity of the histidine kinase domain. Comparison of the Fe-CO coordination geometry between RmFixLT and RmFixLH (heme domain of RmFixL), based on the EXAFS and Raman results, has suggested that the kinase domain directly or indirectly influences steric interaction between the iron-bound ligand and the heme pocket. Referring to the crystal structure of the heme domain of Bradyrhizobium japonicum FixL (Gong, W., Hao, B., Mansy, S. S., Gonzalez, G., Gilles-Gonzalez, M. A., and Chan, M. K. (1998) Proc. Natl. Acad. Sci. U. S. A. 95, 15177-15182), we discussed details of the iron coordination structure of RmFixLT and RmFixLH in relation to an intramolecular signal transduction mechanism in its O(2) sensing.

Bacterial Proteins↗
PubMed1999

Characterization of mouse nNOS2, a natural variant of neuronal nitric-oxide synthase produced in the central nervous system by selective alternative splicing.

Mouse neuronal nitric-oxide synthase 2 (nNOS2) is a unique natural variant of constitutive neuronal nitric-oxide synthase (nNOS) specifically expressed in the central nervous system having a 105-amino acid deletion in the heme-binding domain as a result of in-frame mutation by specific alternative splicing. The mouse nNOS2 cDNA gene was heterologously expressed in Escherichia coli, and the resultant product was characterized spectroscopically in detail. Purified recombinant nNOS2 contained heme but showed no L-arginine- and NADPH-dependent citrulline-forming activity in the presence of Ca2+-promoted calmodulin, elicited a sharp electron paramagnetic resonance (EPR) signal at g = 6.0 indicating the presence of a high spin ferriheme as isolated and showed a peak at around 420 nm in the CO difference spectrum, instead of a 443-nm peak detected with the recombinant wild-type nNOS1 enzyme. Thus, although the heme domain of nNOS2 is capable of binding heme, the heme coordination geometry is highly abnormal in that it probably has a proximal non-cysteine thiolate ligand both in the ferric and ferrous states. Moreover, negligible spectral perturbation of the nNOS2 ferriheme was detected upon addition of either L-arginine or imidazole. These provide a possible rational explanation for the inability of nNOS2 to catalyze the cytochrome P450-type monooxygenase reaction.

Alternative Splicing↗
PubMed1999

Design and synthesis of a globin fold.

We propose a simple method to find an amino acid sequence that is foldable into a globular protein with a desired structure based on a knowledge-based 3D-1D compatibility function. An asymmetric alpha-helical single-domain structure of sperm whale myoglobin consisting of 153 amino acid residues was chosen for the design target. The optimal sequence to fit the main-chain framework has been searched by recursive generation of the protein 3D profile. The heme-binding site was designed by fixing His64 and His93 at the distal and proximal positions, respectively, and by penalizing residues that protrude into the space with a repulsive function. The apparent bumps among side chains in the computer model of the converged, self-consistent sequence were removed by replacing some of the bumping residues with smaller ones according to the final 3D profile. The finally obtained sequence shares 26% of sequence with the natural myoglobin. The designed globin-1 (DG1) with the artificial sequence was obtained by expression of the synthetic gene in Escherichia coli. Analyses using size-exclusion chromatography, circular dichroism spectroscopy, and solution X-ray scattering showed that DG1 folds into a monomeric, compact, highly helical, and globular form with an overall molecular shape similar to the target structure in an aqueous solution. Furthermore, it binds a single heme per protein molecule, which exhibited well-defined spectroscopic properties. The radius of gyration of DG1 was determined to be 20.6 A, slightly larger than that of natural apoMb, and decreased to 19.5 A upon heme binding based on X-ray scattering analysis. However, the heme-bound DG1 did not stably bind molecular oxygen as natural globins do, possibly due to high conformational diversity of side-chain structures observed in the NMR and denaturation experiments. These results give insight into the relationship between the sequence selection and the structural uniqueness of natural proteins to achieve biological functions.

Amino Acid Sequence↗