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Biomedical subjects

T Okabe

Publications and source records attributed to T Okabe.

At least 145 records · Page 8Linked to original sources
PubMed1997

Clinical experience of orthotopic urinary reservoirs in male patients with bladder cancer.

Between 1988 and 1996, 23 male patients with bladder cancer underwent bladder substitution after cystectomy, using either the hemi-Kock, Hautmann, and Reddy procedures. The mean postoperative follow-up period was 36 months, with a range of 3 to 85 months. There were no perioperative deaths, and early postoperative complications occurred in 7 patients (30%); transient urine leak from the pouch in 4, wound infection in 3 and pyelonephritis in 2 patients. Twenty-two of the 23 patients (96%) were continent during the day, while 7 (30%) had nocturnal incontinence. All 3 patients with the Reddy procedure had nocturnal incontinence. Complete continence was preserved in 70% of the patients. Dysuria was seen in 4 patients, including retention in 1 patient. Late complications included urethral stricture in 3, wound hernia in 2, metabolic acidosis in 1, stone in the pouch in 1, and gallbladder stone in 1 patient. However, reoperation was necessary in 1 patient for internal urethrotomy and 1 patient for removal of a stone in the neobladder. Mild degree of hydronephrosis and unilateral reflux were seen in 3 patients each, and followed up conservatively. No urethral recurrence has occurred and only 1 patient died of cancer. The need for reoperation was very low and the high reservoir capacity resulted in continence from the beginning in most patients. We considered the neobladder useful as an alternative form of urinary diversion in selected cases.

Adult↗
PubMed1997

[Ruptured fusiform aneurysm of the basilar artery with minimal atherosclerosis--report of a case].

We reported a case of ruptured fusiform aneurysm of the basilar artery with minimal atherosclerosis. A 51-year-old man was admitted because of subarachnoid hemorrhage (SAH). He had no previous illness and family history. Computed tomographic scan revealed subarachnoid hemorrhage and a fusiform aneurysm in the basilar artery. Cerebral angiography confirmed the presence of the basilar fusiform aneurysm. After four days, the consciousness level worsened and a respiratory support was initiated. The patient died on the fifth hospital day. Autopsy was permitted only to the brain. The brain weighed 1,700 g. Massive subarachnoid hemorrhage was noted at the base of the brain and in the sylvian fissures. A large fusiform aneurysm (30 x 20 x 17 mm) was located in the proximal portion of the basilar artery. Atherosclerotic changes were minimal in the aneurysmal wall and the major extracerebral arteries. SAH was most severe around the aneurysm. The pons showed focal necrosis due to compression by the aneurysm. Microscopically, the aneurysmal wall revealed diffuse attenuation of the muscularis. The elastica also showed a focal defect. We suggest that in the present case of fusiform aneurysm, the pathogenesis is not atherosclerosis but a congenital defect of the muscularis and elastic lamina.

Aneurysm, Ruptured↗
PubMed1997

[The role of nitric oxide in two-kidney, one-clip renovascular hypertensive rats].

The relationship between blood pressure(BP) and nitric oxide(NO) in two-kidney, one-clip renovascular hypertensive rats (2K1C) was investigated. Although urinary NO2- + NO3-(NOx) excretion (UNOX V) increased 2 weeks after surgery (2W-2K1C), UNOX V decreased 4 weeks after surgery (4W-2K1C) compared with that of the control. UNOX V levels were restored 2 weeks after unclipping (U2K1C). BP and UNOX V did not change in 2K1C after treatment with L-arginine (Arg-2K1C). Aorta from 4W-2K1C and Arg-2K1C showed significantly decreased relaxation responses to acetylcholine(Ach), but Ach-induced relaxation of aorta in U2K1C returned to control-level responses. De-endothelialized aorta from 4W-2K1C, Arg-2K1C, and U2K1C had significantly decreased relaxation responses to lipopolysaccharide. These data suggest that: (1) transient increase of NO synthesis is accompanied by elevation of BP, but long-term elevation of BP decreases NO synthesis in endothelium and smooth muscle cells: (2) L-arginine supplement has no effect on the development of hypertension and on NO production by endothelium and smooth muscle cells in 2K1C.

Acetylcholine↗
PubMed1997

[Neoadjuvant CYVADIC (cyclophosphamide, vincristine, adriamycin and dacarbazine) therapy for retroperitoneal leiomyosarcoma: a case report].

Retroperitoneal leiomyosarcoma is often too large to be completely removed. We report a 67-year-old woman successfully treated with neoadjuvant CYVADIC (cyclosphosphamide, vincristine, adriamycin and dacarbazine). The tumor was removed with the right kidney and ureter and a part of the vena cava after 2 courses of CYVADIC. The tumor recurred at the duodenum 7 years later and was completely removed following neoadjuvant CYVADIC. Neoadjuvant chemotherapy could be helpful for the complete resection of advanced leiomyosarcoma.

Aged↗
PubMed1997

Deoxyribonuclease secreted from an insectivorous plant Drosera adelae.

A deoxyribonuclease that is secreted from an insectivorous plant Drosera adelae was partially purified by column chromatography. The enzyme acted as an endonuclease on double-stranded DNA and generated oligonucleotides with 3' hydroxyl and 5' phosphate ends. The activity of the enzyme was high in the range from pH 3.5 to 5.0. The enzyme seemed to require divalent cations for maximum activity.

Animals↗
PubMed1997

Handling characteristics of a gallium alloy triturated with alcohol.

PURPOSE: To assess the handling characteristics of a gallium alloy triturated with one drop (10 microL) of ethyl alcohol and compare them to those of a high-copper amalgam. MATERIALS AND METHODS: A commercial gallium alloy (Gallium Alloy GFII) and a high-copper amalgam (Tytin) were used. Ten dentists each restored four identical MO preparations in acrylic typodont teeth (two for each material). Each restoration was immediately evaluated by the operator for placement, condensation, proximal contact, carving, and resistance to fracture during matrix removal and overall quality according to a method used previously. The rating scale for each criterion ranged from 1 (very poor) to 5 (very good). Scores for each criterion for the amalgam and gallium alloy restorations were statistically compared. RESULTS: The gallium alloy tested was still rated significantly worse (P < or = 0.05) than amalgam for placement, condensation and carving but there were no significant differences in scores for other criteria. The dentists judged the handling of the gallium alloy in all criteria as fair to good and evaluated it as better in placement, condensation and establishment of proximal contact compared to a previous study, mainly because the pre-set material was no longer sticky.

Dental Alloys↗
PubMed1996

Aging and superoxide dismutase activity in cerebrospinal fluid.

We investigated superoxide dismutase (SOD) activity in human cerebrospinal fluid (CSF) as an index of the aging process in the central nervous system (CNS). The subjects were 61 individuals aged 21-77 years, comprising 24 men and 37 women without organic disorders of the nervous system. SOD activity in CSF was measured by the nitrite method modified by Oyanagui. The results showed that SOD activity in CSF gradually increased with age and that the values of SOD activity after the fifth decade were significantly higher than those in the third and fourth decades. It might suggest that the productivity of SOD in the CNS gradually increased with age due to stimulation of various types of oxidative stress which accumulated in vivo especially after the fifth decade.

Adult↗
PubMed1996

Androgen insensitivity syndrome due to new mutations in the DNA-binding domain of the androgen receptor.

Androgen insensitivity syndrome (AIS) is associated with a wide range of quantitative or qualitative defects in the androgen receptor (AR). In some patients with AIS, however, no defects are detectable in the ligand-binding properties of the AR. We have analyzed the ARs of two unrelated patients with this category (termed 'receptor-positive type') of AIS. Sequence analysis of these patients' AR gene revealed single amino acid substitutions (579Cys(TGC)-->Phe(TTC) and 582Phe(TTC)-->Tyr(TAC)) in exon B encoding the first zinc finger of the DNA-binding domain of the AR. These mutations have not been previously reported. Moreover, cotransfection assays and mobility shift assays revealed that these patients' mutant ARs had defective transcriptional activity of the target gene because of impaired DNA-binding ability to the androgen-responsive element. These findings strongly indicate that these mutations are responsible for the pathogenesis of AIS in these patients.

Adult↗
PubMed1996

Confocal fluorescence microscopy for antibodies against a highly conserved sequence in SH2 domains.

We have prepared monoclonal antibodies for a highly conserved sequence (GTFLVRESETTK) in SH2 domains. Mouse IgG1s (12E and 32D) prepared against a peptide-conjugated keyhole lympet hemocyanin specifically bound the antigenic peptide but not the carrier protein. Western blot analysis showed that one IgG1 (12E) recognized mainly 62 kDa proteins (possibly src-family tyrosine kinases) from triton X-100 extracts of RBL-2H3 cells and that another (32D) recognized mainly 32 and 110 kDa proteins. Confocal fluorescence microscopy showed that the SH2 domains had a diffuse cytoplasmic distribution and were not present in the nucleus. Following antigen stimulation, a markedly different cellular distribution was observed in the cells stained with 12E and 32D IgGs. 12E IgGs strongly stained the plasma membranes while 32D IgGs stained small granules in the cytoplasm. As 12E IgGs bound 62 kDa proteins on Western blotting, the results suggest that tyrosine kinases cluster along the plasma membranes and/or than conformational changes occur in the domains after antigen stimulation.

Amino Acid Sequence↗
PubMed1996

Mucopolysaccharidosis IVA: submicroscopic deletion of 16q24.3 and a novel R386C mutation of N-acetylgalactosamine-6-sulfate sulfatase gene in a classical Morquio disease.

The N-acetylgalactosamine-6-sulfate sulfatase (GALNS) gene, which is responsible for autosomal recessive mucopolysaccharidosis IVA (MPSIVA), has been assigned to the long arm of chromosome 16, subregion 24.3, an area where the adenine phosophoribosyltransferase (APRT) gene and renal dipeptidase (DPEP I) gene are also localized. Molecular genetic studies on a severely affected patient with MPSIVA (Morquio disease), without karyotypic abnormality, revealed a partial submicroscopic deletion of 16q24.3 and a single point mutation on the other allele, with no functional GALNS activity. The patient, his mother, and siblings were hemizygous for GALNS and APRT loci, evidenced by informative RFLP and gene dosage analyses combined with a fluorescence in situ hybridization, utilizing a partial genomic clone of GALNS, but heterozygosity was retained at the DPEP I locus and proximal D16S7. Haplotyping of the family members revealed recombinational events between DPEP I locus and three other polymorphic loci on the paternal chromosome, localizing GALNS gene on the proximal side to DPEP I gene. As estimated from the genetic distance between two flanking markers of proximal D16S7 and distal DPEP I locus, size of the deletion was less than 3Mb. Mother of the boy and two older siblings were asymptomatic, despite this interstitial deletion of the Giemsa-light G band. The remaining paternal allele had no gene rearrangement but GALNS activity was not encoded as Arginine at 386 was replaced with Cysteine (R386C), suggesting this alteration accounts for the severe phenotype. Allelic loss of APRT is frequently observed in cancer tissues, thereby suggesting that the tumor suppressor gene locates near the APRT locus. No family member has evidence of any malignant disease. This study is apparently the first documentation of interstitial deletion of 16q24.3, involving GALNS and APRT genes.

Adenine Phosphoribosyltransferase↗
PubMed1996

Cyclic voltammetry of dental amalgams.

OBJECTIVES: This study used cyclic voltammetry to examine the effect of the composition of dental amalgams on their electrochemical behavior, including reactions occurring outside of oral conditions. METHODS: Amalgams (residual mercury 47.5%) were prepared using two low-copper (3 wt% Cu) powders and five high-copper powders (40-80 wt% Ag, 12-30 wt% Cu) with and without zinc (1.5 wt%). Cyclic voltammograms were obtained at 37 degrees C in 1.0% NaCl scanning at 2 mV/s in the potential range from -1.5 V to +0.8 V vs. Ag/AgCl. RESULTS: During the anodic scans, AgCl and Hg2Cl2 films were formed on all amalgams except the one with only 40 wt% Ag. In all high-copper amalgams, a prominent Cu (oxidation) peak was found at -0.1 V, indicating the release of copper during corrosion. Zinc affected the oxidation process for both low- and high-copper amalgams. When zinc was absent, a peak for Sn2+ oxidation appeared at -0.4 V. When zinc was present, a Sn4+ oxidation peak was revealed at -0.6 V. In some amalgams, there was evidence of the selective corrosion (pitting corrosion) of tin and copper. In the lowest silver-content amalgam, no protective films were formed, which is indicative of its poor corrosion resistance. As expected, in all the low-copper amalgams, an extreme increase in current density was recorded immediately at 0 V, due to the release of tin from gamma 2. SIGNIFICANCE: Cyclic voltammetry is useful for the rapid examination (less than an hour) of the electrochemical behavior of amalgams, specifically to obtain information on the formation of compounds and the sequences of electrochemical reactions.

Analysis of Variance↗
PubMed1996

Effect of corrosion on the strength of soldered titanium and Ti-6Al-4V alloy.

OBJECTIVE: Finding an optimal soldering system for a titanium prosthesis has become increasingly important with the successful introduction of titanium and titanium alloys to dentistry. This study examined the effect of corrosion on the strength of the soldered joints of pure titanium and Ti-6Al-4V alloys joined using various solders. METHODS: Commercially pure titanium and Ti-6Al-4V alloy rods (2 mm in diameter; 25 mm long) were soldered in an argon atmosphere using four solders: two kinds of titanium-based solder, a gold-based solder, and a silver-based solder. Tensile strengths were examined before or after immersion treatments. Specimens were immersed in either a 0.9% NaCl or 1.0% lactic acid solution held at 35 degrees C for 3 and 8 wk. The amounts of various metal elements released were determined by atomic absorption photospectroscopy. The natural potentials and potentiodynamic polarization behavior of the soldered specimens in 0.9% NaCl or 1.0% lactic acid were determined by a computer-assisted corrosion measurement system. The results were analyzed by ANOVA and Student's t-test. RESULTS: The cp-titanium and Ti-6Al-4V samples soldered with titanium-based solders exhibited tensile strengths of 300-400 MPa and were not significantly affected by immersion in either solution (no significant difference at p < 0.05). The strengths of both the cp-titanium and titanium alloy specimens soldered with gold-based solder were significantly lower than for any of the other specimens and were affected by immersion in the 0.9% NaCl solution (p < 0.01). The cp-titanium and Ti-6Al-4V specimens that were soldered with titanium-based solders did not show any transpassive regions or breakdown in the natural electrode potential range. On the contrary, the specimens soldered with gold-based and silver-based solders showed transpassive regions or breakdown potentials at less than 0 mV in 0.9% NaCl solution. SIGNIFICANCE: It is recommended that titanium-based solder be employed for titanium and titanium alloys.

Alloys↗
PubMed1996

Mechanical properties of glass ionomers under static and dynamic loading.

OBJECTIVES: This study evaluated the mechanical properties under static and cyclic loading conditions of various types of glass ionomers used for bases and core build-ups under restorations. METHODS: Compressive strength and three-point flexural strength of two different glass ionomers and two metal-reinforced glass ionomers were determined 1 d after the start of mixing. The flexural fatigue resistance of these materials was measured in the load range of 650 g to 1050 g using a three-point bending machine, and fractured surfaces of the specimens were examined using SEM. RESULTS: All the glass ionomers exhibited similar compressive and flexural strengths. The results analyzed by Cox' proportional hazard model demonstrated that the admixed-type metal-reinforced glass ionomer had the highest fatigue resistance, while the water-hardening glass ionomer had the lowest fatigue resistance among the materials examined (p<0.5). SIGNIFICANCE: There was no significant improvement in the static mechanical properties from incorporating metal particles into the glass ionomers. However, the addition of metal particles as in the admixed-type metal-reinforced glass ionomer produced a material with increased fatigue resistance.

Cermet Cements↗
PubMed1996

Abnormalities of sex differentiation.

Sex differentiation is determined by a cascade of events proceeding from chromosomal sex to the completion of sexual maturation at puberty. Many factors involved in this cascade have been identified. Here we focus on DAX-1, androgen receptor and cytochrome P450c17, and discuss their functions in sex differentiation. We analyzed the DAX-1 genes of two unrelated Japanese patients with congenital adrenal hypoplasia and hypogonadotropic hypogonadism using PCR amplification of genomic DNA and complete exonic sequencing, and established that congenital adrenal hypoplasia and hypogonadotropic hypogonadism result from not only inherited but also de novo mutation in the DAX-1 gene. Androgen insensitivity syndrome (AIS) is a good model to clarify the relationship between the structure and function of androgen receptor, the androgen receptor gene mutation and clinical phenotype. We analyzed 15 cases of AIS and demonstrate the structural and functional relationships of the androgen receptor. We have sequenced the CYP17 (P450c17) gene in DNA from several patients with 17 alpha-hydroxylase deficiency, reconstructed the mutations in a human P450c17 cDNA and expressed the mutant P450c17 in COSl cells to characterize the kinetic properties of 17 alpha-hydroxylase and 17,20-lyase activities. The molecular bases of cases clinically reported as 17 alpha-hydroxylase deficiency have turned out to be complete or partial combined deficiencies of 17 alpha-hydroxylase/17,20-lyase.

Adolescent↗
PubMed1996

Setting reactions in dental amalgam. Part 1. Phases and microstructures between one hour and one week.

The literature on the setting mechanisms of dental amalgams made from powders of silver-rich alloys of tin and/or copper has been critically reviewed. In Part 1 of the review, the microstructure and phase content of recently set amalgams are described. The composition, morphology, and location of product phases are emphasized, since these features are clues to the setting reaction. Thus, Part 1 provides the background needed to understand the kinetics of the setting reactions, which is the topic of Part 2 of the review.

Copper↗
PubMed1996

Setting reactions in dental amalgam. Part 2. The kinetics of amalgamation.

The literature on the setting mechanisms of dental amalgams made from powders of silver-rich alloys of tin and/or copper has been critically reviewed. Part 2 is a review of the kinetics of the reactions that convert the mixture of alloy powder and liquid mercury to hardened amalgam containing the phases and microstructures described in Part 1. It is emphasized that amalgamation is a non-equilbrium process in which hardened microstructures are determined as much by kinetics as by chemistry. The setting reaction begins with dissolution of silver and tin into liquid mercury; most of the product phases precipitate in the liquid mercury. The processes that produce supersaturation in the liquid mercury and the subsequent nucleation and growth of solid phases are considered. Mass balance relationships that provide insight into the factors that control the volume fraction of the undesirable gamma 2 Sn-Hg phase are described. The nucleation and growth of eta' Cu-Sn crystals are also discussed; it is found that these crystals nucleate on copper-rich phases and grow into the liquid mercury. Finally, aspects of the setting reaction that are controlled by intergranular and interphase diffusion in the solid are discussed. These aspects include: the supersaturation of silver and tin within the liquid mercury, nucleation and growth of the beta 1 Ag-Hg phase in the surfaces of alloy particles, and the decomposition of initially formed gamma 2 Sn-Hg.

Anisotropy↗