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Biomedical subjects

Y Yoshida

Publications and source records attributed to Y Yoshida.

At least 289 records · Page 16Linked to original sources
PubMed1999

External iliac artery occlusion in posterior spinal surgery.

STUDY DESIGN: Report of a case of external iliac artery occlusion occurring as a rare complication of lumbar posterior spinal surgery. OBJECTIVE: To clarify the cause of this rare complication and recommend methods for preventing its recurrence. SUMMARY OF BACKGROUND DATA: Several cases of central retinal artery occlusion after posterior spinal surgery have been reported, but there has been no reported case of external iliac artery occlusion after posterior spinal surgery. METHODS: A 65-year-old woman who had a 32-year history of systemic lupus erythematosus underwent posterior decompression and spinal fusion for degenerative scoliosis. She was supported on a Hall frame during the operation. Three hours after surgery, paralysis and sensory impairment of the left leg and cyanosis of the toes of the left foot were noted. The popliteal, dorsalis pedis, and posterior tibial pulses were not palpable. Angiography showed complete occlusion of the external iliac artery, and emergency removal of the thrombus was performed. RESULTS: One year later, neurologic symptoms were absent, and the leg vessels were normal. CONCLUSIONS: Prolonged direct pressure on the inguinal region during posterior spinal surgery on a Hall frame may cause external iliac artery occlusion. Early recognition and adequate treatment can prevent serious sequelae.

Aged↗
PubMed1999

Gab-family adapter proteins act downstream of cytokine and growth factor receptors and T- and B-cell antigen receptors.

We previously found that the adapter protein Gab1 (110 kD) is tyrosine-phosphorylated and forms a complex with SHP-2 and PI-3 kinase upon stimulation through either the interleukin-3 receptor (IL-3R) or gp130, the common receptor subunit of IL-6-family cytokines. In this report, we identified another adapter molecule (100 kD) interacting with SHP-2 and PI-3 kinase in response to various stimuli. The molecule displays striking homology to Gab1 at the amino acid level; thus, we named it Gab2. It contains a PH domain, proline-rich sequences, and tyrosine residues that bind to SH2 domains when they are phosphorylated. Gab1 is phosphorylated on tyrosine upon stimulation through the thrombopoietin receptor (TPOR), stem cell factor receptor (SCFR), and T-cell and B-cell antigen receptors (TCR and BCR, respectively), in addition to IL-3R and gp130. Tyrosine phosphorylation of Gab2 was induced by stimulation through gp130, IL-2R, IL-3R, TPOR, SCFR, and TCR. Gab1 and Gab2 were shown to be substrates for SHP-2 in vitro. Overexpression of Gab2 enhanced the gp130 or Src-related kinases-mediated ERK2 activation as that of Gab1 did. These data indicate that Gab-family molecules act as adapters for transmitting various signals.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Stimulation of myelin basic protein gene transcription by Fyn tyrosine kinase for myelination.

Myelin is synthesized about the time of birth. The Src-family tyrosine kinase Fyn is involved in the initial events of myelination. Fyn is present in myelin-forming cells and is activated through stimulation of cell surface receptors such as large myelin-associated glycoprotein (L-MAG). Here we show that Fyn stimulates transcription of the myelin basic protein (MBP) gene for myelination. MBP is a major component of the myelin membrane. In 4-week-old Fyn-deficient mice, MBP is significantly reduced, and electron microscopic analysis showed that myelination is delayed, compared with wild-type mice. The Fyn-deficient mice had thinner, more irregular myelin than the wild-type. We found that Fyn stimulates the promoter activity of the MBP gene by approximately sevenfold. The region responsible for the transactivation by Fyn is located between nucleotides -675 and -647 with respect to the transcription start site. Proteins binding to this region were found by gel shift study, and the binding activity correlates with Fyn activity during myelination. These results suggest that transactivation of the MBP gene by Fyn is important for myelination.

Amino Acid Sequence↗
PubMed1999

Development of the arbitrarily primed-representational difference analysis method and chromosomal mapping of isolated high throughput rat genetic markers.

Linkage mapping of quantitative trait loci requires analysis of a large number of animals. Although genetic markers isolated by representational difference analysis (RDA) and its modifications meet the needs, the number of these markers has been limited. In the present study, we established the arbitrarily primed (AP)-RDA method to isolate virtually an unlimited number of the high throughput genetic markers. A representation of the genome, an AP-amplicon, was prepared by AP-PCR with a single primer or with a combination of primers using genomic DNA of the ACI/N (ACI) or BUF/Nac (BUF) rat as a template. By subtracting the AP-amplicon of ACI from that of BUF, a total of 40 polymorphic and independent markers were isolated in seven series of AP-RDA using a single primer. Two series of AP-RDA with primer combination yielded seven additional independent markers. All of the markers gave clear positive/negative signals by hybridization of a filter where AP-amplicons from F2 rats of ACI and BUF were dot-blotted at a high density without any concentration or purification. All of the 47 independent markers were mapped to unique chromosomal positions by linkage analysis, even though some arbitrary primers had very similar sequences. The markers were also informative between other strains of rats. Simultaneous hybridization of multiple filters made it possible to genotype a large number of rats simultaneously for multiple genetic loci. The AP-RDA method promises isolation of a large number of high throughput genetic markers in any species and is expected to facilitate linkage mapping of subtle quantitative trait loci.

Animals↗
PubMed1999

Cell-free production and stable-isotope labeling of milligram quantities of proteins.

We have improved the productivity of an Escherichia coli cell-free protein synthesis system. First, creatine phosphate and creatine kinase were used as the energy source regeneration system, and the other components of the reaction mixture were optimized. Second, the E. coli S30 cell extract was condensed by dialysis against a polyethylene glycol solution to increase the rate of synthesis. Third, during the protein synthesis, the reaction mixture was dialyzed against a low-molecular-weight substrate solution to prolong the reaction. Thus, the yield of chloramphenicol acetyltransferase was raised to 6 mg/ml of reaction mixture. Stable-isotope labeling of a protein with 13C/15N-labeled amino acids for NMR spectroscopy was achieved by this method.

Biotechnology↗
PubMed1999

A novel approach to AFM characterization of adhesive tooth-biomaterial interfaces.

A novel approach is proposed for studying tooth-biomaterial interactions with high resolution. Thus far, polished interfaces examined by AFM have not disclosed much detail, mainly due to the destruction of soft surface texture and the smearing of polishing debris across the interface that obscures the actual ultra-structure. Therefore the practical utility of diamond-knife microtomy as a sample preparation technique for imaging tooth-biomaterial interfaces by AFM with high resolution was tested in this study and compared to that of ultra-fine mechanical polishing techniques. The AFM images clearly demonstrated the enhanced potential of diamond-knife microtomy for nondestructively producing clean cross-sections through interfaces that allow the interfacial ultra-structure to be imaged by AFM with a resolution equaling that of TEM. This novel approach opens the field to the full range of scanning probe microscopy, including physical and chemical surface characterization of interfaces with a mix of soft and hard substrates.

Dental Cements↗
PubMed1999

New methods of control against postoperative methicillin-resistant Staphylococcus aureus infection.

The incidence of postoperative infections caused by methicillin-resistant Staphylococcus aureus (MRSA) in Japan has been increasing dramatically. In March 1990, we assigned special doctors in infection control (infection control doctor, ICD), and defined comprehensive controls against MRSA infection. A total of 3536 cases of digestive tract surgery performed at our department were studied during the period between September 1987 and August 1997. We changed the use of antibiotics to prevent postoperative infection. Cefazolin (CEZ) was employed for surgery of the upper digestive tract, including esophagus, stomach, duodenum, and gallbladder. Cefotiam (CTM) was employed for surgery of the lower digestive tract, liver, and pancreas. In esophageal resection, the tracheal tube was extracted during the early postoperative period, and for cervical esophagogastroanastomosis, the autosuture was changed to layer-to-layer anastomosis. We have achieved successful control of postoperative MRSA infection, the incidence having decreased to 0.3% (9/2703). In conclusion, our methods of control against postoperative MRSA infection implies that comprehensive measures of prevention, including the reviewed specification and usage of antibiotics and operation management, have been well implemented. This value is the lowest and the first of any domestic hospital or institute in Japan, suggesting a continued and significant decrease.

Cephalosporins↗
PubMed1999

Methicillin-resistant Staphylococcus aureus proliferation in the rat gut is influenced by gastric acid inhibition and the administration of antibiotics.

The author studied methicillin-resistant Staphylococcus aureus (MRSA) proliferation in the rat gut which was influenced by gastric acid inhibition and the administration of antibiotics. When male Wistar rats were bred by total parenteral nutrition (TPN), and were continuously administered famotidine 4 mg/kg per day, the gastric acidity was observed to decrease to pH 6.4+/-0.1. However, when they were bred by TPN, and histamine 4 mg/kg per hour was continuously administered, the gastric acidity was observed to increase to pH 1.9+/-0.4. MRSA was thus able to cross over to the small intestine only during the famotidine medication. If rats were intravenously administered latamoxef (LMOX) after an oral inoculation of MRSA, then the viable MRSA counts in the stomach, small intestine, and large intestine all decreased on day 4. In contrast, if the gastric acidity decreased and the rats were treated by an oral administration of kanamycin and metronidazole before an oral inoculation of MRSA and thereafter were administered LMOX, then the MRSA count significantly increased. It is thus concluded that a suppression of gastric acid and a great disorder of the intestinal flora is indispensable for the colonization of MRSA into the small intestine, while in vitro the propagation of MRSA requires a continuity of suppression absent in the bacterial flora.

Animals↗
PubMed1999

Anterior sacral meningocele completely occupied by an epidermoid tumor.

A 2-year-old girl presented with an anterior sacral meningocele completely occupied by an epidermoid tumor. Preoperative magnetic resonance imaging had shown the meningocele with contents of the same intensity as cerebrospinal fluid. Surgery via a posterior sacral approach disclosed the tumor beneath an unexpected membrane inside the meningocele. Additionally, the presence of pus inside epidermoid tumor suggested that possible episodes of asymptomatic meningitis or other infection might have occurred before treatment, these being the major complication in anterior sacral meningocele. Therefore, we recommend that surgical treatment should be performed at the earliest possible stage in childhood, once the diagnosis is established, and dural plasty carried out to prevent infectious complications.

Child, Preschool↗
PubMed1999

Absence of Mycobacterium paratuberculosis DNA in intestinal tissues from Crohn's disease by nested polymerase chain reaction.

A role of Mycobacterium paratuberculosis in Crohn's disease has been suggested for many years. To determine whether Mycobacterium paratuberculosis has the potential to cause Crohn's disease, we investigated Crohn's disease tissues for the presence of Mycobacterium paratuberculosis, using highly sensitive nested polymerase chain reaction (PCR). DNA was extracted from samples of intestine obtained from 13 patients with Crohn's disease, 14 patients with ulcerative colitis, and 13 control patients without inflammatory bowel disease. Nested PCR was performed using primer pairs complementary to sequences in the insertion element IS900 gene of Mycobacterium paratuberculosis. No Mycobacterium paratuberclulosis-specific PCR product was detected in any of these specimens, although PCR products of the appropriate size were consistently obtained using control DNA template from Mycobacterium paratuberculosis. The results did not suggest that Mycobacterium paratuberculosis is involved in the pathogenesis of Crohn's disease.

Adolescent↗
PubMed1999

Superficial blood flow, blood volume, and blood velocity in colorectal tubular adenomas and adenocarcinomas.

To clarify differences in the vasculature of benign and malignant colorectal tumors, we compared blood flow (which has been examined in previous studies) as well as blood volume and blood velocity in two types of human colorectal tumors. We measured blood flow and blood volume with an endoscopic laser-Doppler flowmeter in the lesions and the normal mucosa near the lesions of 79 tubular adenomas with mild dysplasia and 38 adenocarcinomas. Blood velocity was defined as blood flow per blood volume. The ratio of each value in the lesions to that in the neighboring normal mucosa was defined as the relative value, and the mean relative values in the two groups were compared. The relative blood flow was 1.89 +/- 0.64 in the tubular adenomas and 1.49 +/- 0.66 in the adenocarcinomas (P < 0.005), and the relative blood volume was 1.10 +/- 0.14 and 0.90 +/- 0.13, respectively (P < 0.001). The relative blood velocity was approximately 1.7 in both groups (NS). This study demonstrated that the superficial blood flow in adenocarcinomas is increased due to increased blood velocity, despite blood volume being decreased.

Adenocarcinoma↗
PubMed1999

A new endoscopic metallic stenting method for duodenal stenosis: a preliminary report.

Palliative duodenal stenting was attempted in three patients with severe duodenal stenosis due to tumor invasion. Two methods were applied for duodenal stenting: the conventional method, which inserts the Ultraflex (stent for esophageal stenosis) along the guidewire under fluoroscopy, and a new method that uses a snare and an endoscope to guide the esophageal stent. The conventional method is often unsuccessful, because the delivery tube is too short, but the latter method appears to be a safe and effective duodenal stenting technique.

Aged↗
PubMed1999

A novel amino acid substitution at the receptor-binding site on the hemagglutinin of H3N2 influenza A viruses isolated from 6 cases with acute encephalopathy during the 1997-1998 season in Tokyo.

We analyzed the hemagglutinin (HA) genes of influenza A viruses consisting of 6 strains isolated from cerebrospinal fluids of patients with encephalopathy and 3 isolates from throat washes of patients without central nervous system symptoms during the 1997-1998 season in Tokyo. Aligned 9 amino acid sequences showed 7 common substitutions compared with A/Wuhan/359/95 (vaccine strain used in the season in Japan), which were allocated to three different antigenic sites on the H3 HA molecule. It is noted that a novel substitution at the receptor-binding site (Tyr-137 to Phe) was found exclusively in the isolates from the patients with encephalopathy.

Amino Acid Sequence↗
PubMed1999

Localization of neuronal-constitutive nitric oxide synthase and secretory regulation by nitric oxide in the rat submandibular and sublingual glands.

The distribution of neuronal-constitutive nitric oxide synthase (ncNOs)-positive nerve fibres was compared immunohistochemically, and the effect of NOs inhibitor and NO scavenger on the secretory response was compared functionally, in the two glands. Numerous ncNOs-positive fibres were distributed around acini in the submandibular gland but scarcely any around acini in the sublingual gland. Within the submandibular ganglion (parasympathetic), the nerve-cell bodies were strongly positive. Within the superior cervical ganglion (sympathetic), the nerve-cell bodies were negative, although some positive nerve fibres were observed. The secretory responses to the electrical stimulation of the chorda were significantly reduced by the NOs inhibitor, N(G)-nitro-L-arginine methyl ester (L-NAME, 10(-9)-10(-3) M) in a dose-dependent manner. The NO scavenger, 2-(4-carboxyphenyl)4,4,5,5-tetramethylimidazoline-1-oxyl 3-oxide (carboxy-PTIO) also reduced the chorda-evoked secretion (10(-9)-10(-6) M). The submandibular secretions evoked by stimulation of the superior cervical ganglion were not affected by L-NAME or carboxy-PTIO. In the sublingual gland, neither L-NAME nor carboxy-PTIO affected chorda-evoked salivary secretion. The histochemical and functional results both suggest that NO plays an excitatory role in the regulation of parasympathetic nerve-induced salivary secretion in the rat submandibular gland, but not in the sublingual gland.

Animals↗
PubMed1999

Porcelain veneers bonded to tooth structure: an ultra-morphological FE-SEM examination of the adhesive interface.

OBJECTIVES: The porcelain veneer technique bonds a thin porcelain shell to a minimally prepared tooth surface (enamel and/or dentin) with a luting composite in combination with an adhesive system. When complete, two adhesive interfaces are formed--resin to etched porcelain and resin to tooth structure. The purpose of this laboratory investigation is to analyze the ultra-structure of these two adhesive interfaces in order to find an explanation for some clinical phenomena and/or shortcomings of bonded porcelain veneers. METHODS: The surfaces of four porcelain disks were treated successively by sandblasting, etching with hydrofluoric acid, ultrasonic cleaning, and silanizing. The effect of each step on the surface structure of the porcelain was evaluated by field-emission scanning electron microscopy (FE-SEM). In addition, the effect of acid etching the tooth surface of veneer preparations on seven extracted upper anterior teeth was similarly determined. Finally, pre-treated porcelain veneers were luted to veneer preparations on 12 extracted upper anterior teeth by means of a contemporary total-etch adhesive system and a photo-polymerizable luting composite. The tooth/luting composite and the luting composite/porcelain interface of the veneer complex were then evaluated ultra-morphologically by FE-SEM after the specimens had been etched with an argon-ion beam to enhance the surface relief. RESULTS: FE-SEM imaging of the tooth/luting composite/porcelain interface showed strong micro-mechanical interlocking of the luting composite in the micro-retentive pits both of the acid-etched tooth surface and in the etch pits of the acid-etched porcelain surface. From this ultra-morphological perspective, the etched porcelain surface is more retentive than the etched tooth surface. At the tooth surface, cervical aprismatic enamel and exposed dentin showed the least resin-receptive surface texture. However, in these areas, no separation of the interface was observed when a multi-step total-etch adhesive system was used. SIGNIFICANCE: The strong interlocking of the luting composite into the retentive etch pits of both the porcelain and tooth substrates contributes to strong adhesion of porcelain veneers with good retention. This study suggests that a modern multi-step total-etch adhesive system can produce adhesion even to the less retentive cervical enamel and exposed dentin. Further clinical research is necessary to evaluate the long-term retention of porcelain veneers and to correlate these in vitro observations with clinical performance.

Acid Etching, Dental↗
PubMed1999

Hair dye use and occupational exposure to organic solvents as risk factors for myelodysplastic syndrome.

To investigate the relationships of personal hair dye use and environmental factors to myelodysplastic syndromes (MDS), we conducted a case-control study in Japan. A total of 111 MDS cases and 830 controls randomly selected from the residents in the same prefecture of cases using telephone directories responded to a health questionnaire. The odds ratio (OR) for ever having used hair dye was 1.99 (95% confidence interval (CI) 1.17-3.38) and there were statistically significant trends in risk with increasing duration and number of hair dye use. Occupational exposure to organic solvents was marginally associated with the risk of MDS (OR = 1.99; 95% CI 0.97-4.10).

Adult↗