Biomedical subjects

H Kawahara

Publications and source records attributed to H Kawahara.

At least 19 recordsLinked to original sources

PubMed2006

Electron microscopic investigation on the osteogenesis at titanium implant/bone marrow interface under masticatory loading.

Electron microscopic investigation on osteogenetic process at the implant surface of threadless rod-type titanium implants with different surface roughness of Ra 0.4 +/- 0.01 microm, Sm 2.6 +/- 0.3 microm and Ra 2.0 +/- 0.12 microm, Sm 36 +/- 9.1 microm was performed at the early stage of 21 and 42 days post implantation into the jawbones of four beagles under the load bearing condition of functional mastication. The implant surfaces were covered with a blood clot and haematopoietic stem cells (HSC) including phagocytic monocytes immediately after the implantation. Successively, osteogenic stem cells (OSC) migrated from cortical and/or trabecular endosteum to the HSC-layer on the implant surface. The new bone formation at the implant/bone marrow interface was developed by collaboration of osteomediator cells (OMC) differentiated from monocytes of HSC and osteoblast phenotype cells of OSC derived from endosteum of cortical bone and/or trabecular. The new bone layer at the implant surface consisted of two layers, solution-mediated calcification layer of pseudo bone and cell (osteoblast) -mediated calcification layer of true bone. The pseudo bone was produced by solution-mediated calcification of OMC- and HSC-remnants near by the implant surface. The bone healing process at the implant/bone marrow interface depended upon two factors; the migration of OSC from cortical and/or trabecular endosteum to the implant surface and the healing potentiality. Topographic dependency upon the bone healing potential at implant/bone marrow interface was not confirmed in this experiment under the load bearing condition of functional mastication.

Animals↗

PubMed2006

No evidence to indicate topographic dependency on bone formation around cp titanium implants under masticatory loading.

In vitro studies have proved the topographic dependency upon osteogenesis on titanium plate by investigating the cell-adhesion, -shape, -proliferation, -differentiation, ALP activity and osteocalcin production of osteogenic stem cells, MG36, MC3T3-E1 and wild strains of bone formative cells from animal and human. However, this in vivo study on bone growth around cp titanium dental implants under masticatory loading did not demonstrate significant difference among the different surface roughness in the range of Ra 0.4-1.9 microm, Rz 2.8-11.2 microm, Rmax 3.6-28.1 microm and Sm 2.9-41.0 microm, which was estimated by measuring the bone contacts, bone occupancies and bone bonding strengths at the implant/bone marrow interface. It is revealed that the topographic dependency on the osteogenetic activity is apt to be covered with wide variation in bone healing potential under the clinical condition with functional biting load.

Animals↗

PubMed2005

Laparoscopic percutaneous extraperitoneal closure (LPEC) method for the exploration and treatment of inguinal hernia in girls.

We recently introduced the laparoscopic percutaneous extraperitoneal closure (LPEC) method for the treatment of girls with inguinal hernia. Using the LPEC method, 129 girls underwent laparoscopic herniorrhaphy. A 5 mm laparoscope was inserted via the umbilicus. A 3 mm "snake retractor" was advanced through the lateral abdominal wall to measure the length of the hernia sac and contralateral patent processus vaginalis (PPV), respectively. The hernia sac and PPV were closed at the level of the internal inguinal ring with a 2-0 non-absorbable purse-string suture using Lapaherclosure, a special 19G needle that can hold a suture at the tip. The length of the hernial sac was significantly longer than that of contralateral PPV (mean 41 mm; range 18-70 mm; P < 0.05). There were no serious complications associated with the procedure. No recurrence of hernia or metachronous contralateral hernia has been identified so far. This approach enables us to perform contralateral exploration without any additional techniques, followed by immediate and accurate closure of the hernia sac and PPV. We conclude that the LPEC method is a safe and efficacious procedure with a low recurrence rate that should be viewed as an acceptable alternative to the traditional open approach.

Child↗

PubMed2005

Knocking out ubiquitin proteasome system function in vivo and in vitro with genetically encodable tandem ubiquitin.

At present, the 26S proteasome-specific inhibitor is not available. We constructed polyubiquitin derivatives that contained a tandem repeat of ubiquitins and were insensitive to ubiquitin hydrolases. When these artificial polyubiquitins (tUbs, tandem ubiquitins) were overproduced in the wild-type yeast strain, growth was strongly inhibited, probably because of inhibition of the 26S proteasome. We also found that several substrates of the ubiquitin-proteasome pathway were stabilized by expressing tUbs in vivo. tUbs containing four units or more of the ubiquitin monomer were found to form a complex with the 26S proteasome. We showed that tUb bound to the 26S proteasome inhibited the in vitro degradation of polyubiquitinylated Sic1 by the 26S proteasome. When tUB6 (six-mer) messenger RNA was injected into Xenopus embryos, cell division was inhibited, suggesting that tUb can be used as a versatile inhibitor of the 26S proteasome.

Animals↗

PubMed2004

In vitro study on bone formation and surface topography from the standpoint of biomechanics.

Effect of surface topography upon cell-adhesion, -orientation and -differentiation was investigated by in vitro study on cellular responses to titanium substratum with different surface roughness. Cell-shape, -function and -differentiation depending upon the surface topography were clarified by use of bone formative group cells (BFGCs) derived from bone marrow of beagle's femur. BFGCs consisted of hematopoietic stem cells (HSC) and osteogenetic stem cells (OSC). Cell differentiation of BFGCs was expressed and promoted by structural changes of cytoskeleton, and cell-organella, which was caused by mechanical stress with cytoplasmic stretching of cell adhesions to the substratum. Phagocytic monocytes of HSC differentiated to osteomediator cells (OMC) by cytoplasmic stretching with cell adhesion to the substratum. The OMC mediated and promoted cell differentiation from OSC to osteoblast through osteoblastic phenotype cell (OBC) by cell-aggregation of nodules with "pile up" phenomenon of OBC onto OMC. The osteogenesis might be performed by coupling work of both cells, OMC originated from monocyte of HSC and OBC originated from OSC, which were explained by SEM, TEM and fluorescent probe investigation on BFGCs on the test plate of cp titanium plates with different topographies. This osteogenetic process was proved by investigating cell proliferation, DNA contents, cell-adhesion, alkaline phosphatase activity and osteocalcine productivity for cells on the titanium plates with different topographies. The study showed increased osteogenic effects for cells cultured on Ti with increased surface roughness. Possible mechanisms were discussed from a biomechanical perspective.

Animals↗

PubMed2004

Clinical outcome of laparoscopically assisted endorectal pull-through in Hirschsprung's disease: comparison of abdominal and perineal approaches.

BACKGROUND/PURPOSE: Laparoscopically assisted endorectal pull-through (EPT) via a perineal approach using a prolapsing technique (PA) for Hirschsprung's disease (HD) has been reported. However, the clinical outcome after this approach has not been reported. The purpose of this study was to compare the clinical outcome of PA and the conventional transabdominal approach (TA). METHODS: In the period between 1990 and 2001, 20 cases of HD underwent EPT with TA (group O), and 21 underwent EPT with PA (group L). There was no difference in age and weight distribution between the 2 groups. Clinical outcome was assessed 3 years after surgery. RESULTS: The operation time was comparable in the 2 groups (4.9 +/- 0.8 v 5.2 +/- 0.8 hr), whereas blood loss (98 +/- 52 v 36 +/- 30 mL) and postoperative complications requiring surgical intervention (26% v 0%) were significantly lower in group L. The incidence of postoperative enteritis (27% v 28%) and voluntary defecation (more than once every/2 days) were compatible in the 2 groups (70% v 87%). Soiling (small amount of involuntary stooling; >1 per month) was significantly less frequent in group L (45% v 14%). CONCLUSIONS: Laparoscopically assisted ETP with PA is less invasive and can provide a better clinical outcome compared with TA in terms of postoperative soiling.

Abdomen↗

PubMed2003

Laparoscopic intervention for intrathoracic stomach in infants.

BACKGROUND: Intrathoracic stomach is an uncommon condition in infants. We report our experience managing such a condition successfully by laparoscopy in four patients. METHODS: Patients' ages at the time of operation ranged from 30 days to 14 months. In all cases, the intrathoracic stomach was easily pulled down into the abdominal cavity. The phrenoesophageal ligament was completely resected, and the enlarged hiatus was narrowed by intraabdominal suturing technique. The esophagus was wrapped with the mobilized fundus in a floppy fundoplication. Anchoring sutures were placed between the wrapping cuff and crura. RESULT: One patient had paraesophageal hernia (type 2), whereas the other had combined hiatal hernia (type 3). No adverse complications were observed in any of the cases. Symptomatic gastroesophageal reflux and radiographic recurrence of hernia were not seen in any case. The cosmesis was excellent in all cases. CONCLUSIONS: We conclude that laparoscopic repair for intrathoracic stomach is a safe and feasible method when preoperative evaluation is conducted adequately.

Hernia, Hiatal↗

PubMed2003

Proposal of fibrosis index using image analyzer as a quantitative histological evaluation of liver fibrosis in biliary atresia.

This study was designed to elucidate whether the fibrosis index (FI), which was measured as a ratio of histological fibrotic tissue area to the whole area using an image analyzer, could reflect liver function and long-term prognosis in biliary atresia (BA). Liver biopsies were performed in 46 BA patients at hepatic portoenterostomy (HPE) and stoma closure. The chronological difference rate of FI (FIDR) was the monthly FI difference between HPE and stoma closure. FI at HPE and stoma closure was significantly higher than in the control. FI at HPE and at stoma closure significantly correlated with gammaGTP or T.Bil, D.Bil, cholinesterase and total bile acid, respectively. FIDR in jaundice-free group was significantly lower than in jaundiced group at 5 years after HPE. FIDR in V-2 (varices with red-color sign) was significantly higher than in V-0 (no varices) or V-1 (varices without red-color sign). ICG-K value significantly correlated with FIDR. FI at stoma closure or FIDR was significantly lower in living patients than in patients who eventually died or underwent liver transplantation. In conclusion, FI can reflect the degree of cholestasis in BA. FIDR would be useful for predicting long-term outcome in BA.

Analysis of Variance↗

PubMed2003

Endorectal pull-through with posterior sagittal approach to the repair of postoperative rectourethral and rectovaginal fistula.

BACKGROUND/PURPOSE: Rectourethral (RUF) or rectovaginal fistula (RVF) is a troublesome complication after anorectal surgery because of dense adhesions around the fistula. The authors applied a new technique for the redo surgery. METHODS: Case 1 is Hirschsprung's disease in a 1-year-old boy who underwent modified Duhamel's procedure and had RUF. Case 2 is rectovestibular fistula in an 11-year-old girl who had anterior sagittal anorectoplasty complicated by RVF. Case 3 is multiple urogenital anomalies including rectovesical fistula in a 4-year-old boy in whom transvesical repair was unsuccessful. The colon was mobilized as far as possible at laparotomy. The rectum was opened via a posterior sagittal approach leaving 1 cm of the anal canal. Extended endorectal mucosectomy was performed to the dentate line, and the fistula was closed from inside of the rectum. The remaining mucosal cuff was everted out of the anus and the intact colon was pulled through the rectum and anastomosed to the cuff extraanally. RESULTS: The postoperative contrast enema showed no recurrent fistula, and defecation was not impaired. CONCLUSIONS: Endorectal pull-through of the intact colon can spare troublesome mobilization of the fistula and can prevent the recurrence of fistula. Rectal incision via a posterior sagittal approach provides a direct view of the fistula.

Child↗

PubMed2002

Mechanisms responsible for recurrent gastroesophageal reflux in neurologically impaired children who underwent laparoscopic Nissen fundoplication.

BACKGROUND: In this study, we attempted to define the lower esophageal sphincter (LES) motor events associated with the occurrence of gastroesophageal reflux (GER) in neurologically impaired children in whom of GER disease recurred after laparoscopic Nissen fundoplication (LNF). METHODS: Of 45 neurologically impaired children who had previously undergone LNF, six children in whom recurrence of GER disease was documented by 24-h esophageal pH monitoring were studied. Concurrent esophageal manometry and pH monitoring were conducted for 1 h both before and after the administration of apple juice (10 ml/kg). RESULTS: A total of 89 reflux episodes were recorded in the course of the study. Of these, 51 episodes (57%) were associated with transient LES relaxation. In the remainder, reflux occurred across a contracted LES in 21 episodes (24%) and during absent basal LES tone in 15 episodes (17%). In four of six patients, transient LES relaxation was responsible for more than half of the reflux episodes. CONCLUSION: Transient LES relaxation is the predominant mechanism of reflux in neurologically impaired children with recurrent GER after LNF.

Child↗

PubMed2002

Intravenous atropine treatment in infantile hypertrophic pyloric stenosis.

AIMS: To assess the efficacy of a new regimen of intravenous atropine treatment for infantile hypertrophic pyloric stenosis (IHPS) with special reference to regression of pyloric hypertrophy. METHODS: Atropine was given intravenously at a dose of 0.01 mg/kg six times a day before feeding in 19 patients with IHPS diagnosed from radiographic and ultrasonographic findings. When vomiting ceased and the infants were able to ingest 150 ml/kg/day formula after stepwise increases in feeding volume, they were given 0.02 mg/kg atropine six times a day orally and the dose was decreased stepwise. RESULTS: Of the 19 infants, 17 (89%) ceased projectile vomiting after treatment with intravenous (median seven days) and subsequent oral (median 44 days) atropine administration. The remaining two infants required surgery. No significant complications were encountered. Ultrasonography showed a significant (p < 0.05) decrease in pyloric muscle thickness, but no significant shortening of the pyloric canal after completion of the atropine treatment. The patients exhibited failure to thrive at presentation, but were thriving at 6 months of age (p < 0.01). CONCLUSIONS: This atropine therapy resulted in satisfactory clinical recovery. Pyloric muscle thickness was significantly reduced.

Atropine↗

PubMed2002

Dynamic load at baseline can predict radiographic disease progression in medial compartment knee osteoarthritis.

OBJECTIVE: To test the hypothesis that dynamic load at baseline can predict radiographic disease progression in patients with medial compartment knee osteoarthritis (OA). METHODS: During 1991-93 baseline data were collected by assessment of pain, radiography, and gait analysis in 106 patients referred to hospital with medial compartment knee OA. At the six year follow up, 74 patients were again examined to assess radiographic changes. Radiographic disease progression was defined as more than one grade narrowing of minimum joint space of the medial compartment. RESULTS: In the 32 patients showing disease progression, pain was more severe and adduction moment was higher at baseline than in those without disease progression (n=42). Joint space narrowing of the medial compartment during the six year period correlated significantly with the adduction moment at entry. Adduction moment correlated significantly with mechanical axis (varus alignment) and negatively with joint space width and pain score. Logistic regression analysis showed that the risk of progression of knee OA increased 6.46 times with a 1% increase in adduction moment. CONCLUSIONS: The results suggest that the baseline adduction moment of the knee, which reflects the dynamic load on the medial compartment, can predict radiographic OA progression at the six year follow up in patients with medial compartment knee OA.

Aged↗

PubMed2002

Actigraphic assessment of the preoperative hypnotic effects of brotizolam and zopiclone.

Brotizolam and zopiclone have a common ability to bind to the benzodiazepine recognition site and have been used as useful preoperative hypnotics. The aim of the present study was the quantitative evaluation of the preoperative hypnotic effects of brotizolam and zopiclone by actigraphy. Forty patients received brotizolam 0.25 mg (group B) or zopiclone 7.5 mg (group Z) in randomized manner at 21:30 on the night before surgery. Sleep and awake was identified by wrist activity measured with a motion-logger actigraph. Sleep time was assessed in total period from 22:00 to 6:00 and its 4 subdivided 2-hour periods (22:00-24:00, 24:00-2:00, 2:00-4:00, 4:00-6:00). The total sleep time in group B (448 +/- 23 min) was significantly longer than that in group Z (416 +/- 43 min). Group Z showed a significant reduction in sleep time in period 4 (4:00-6:00), compared with other periods, whereas group B did not show any difference among 4 periods. In comparison of each period between 2 groups, group B showed significant longer sleep time in period 4. An actigraphic assessment of sleep time has demonstrated the quantitative difference of the effects of brotizolam and zopiclone as preoperative hypnotics.

Adult↗

PubMed2002

Effect of artificial carbon dioxide foot bathing on critical limb ischemia (Fontaine IV) in peripheral arterial disease patients.

BACKGROUND: It has been reported that artificial carbon dioxide (CO(2)) foot bathing improves subcutaneous microcirculation in peripheral arterial disease (PAD) patients. However, the effect for critical limb ischemia (CLI) with ulceration or gangrene (Fontaine stage IV) is not identified. The physiological effects of CO(2) bathing and the outcome of limb salvage in such patients were studied. METHODS: In 18 healthy volunteers (Study I), the dorsal pedis peripheral blood flow was measured by a laser Doppler flow-meter during CO(2) foot bathing (1000 ppm, 37 degrees C) for 10 min. A Holter electrocardiogram was also recording in the same period. Blood flow and cell volume significantly increased during bathing. Eighty-three CLI limbs (Fontaine IV) in 68 PAD patients (Study II) underwent artificial CO(2) foot bathing (for 10 minutes twice daily >2 months) were followed up >6 months. RESULTS: In Study I, analysis of heart rate variability showed that high frequency amplitude (HFA) considerably increased and the ratio of low frequency amplitude to HFA (LF/HF) noticeably decreased during bathing. In Study II, 69 limbs (83.1%) could be salvaged. Twenty-seven of 28 limbs (96.4%) which have ulcer and gangrene in only one toe, 13/16 limbs (81.2%) in multiple toes and 29/39 limbs (74.4%) in all toes and/or heel respectively were saved. CONCLUSIONS: The effect of CO(2) enriched water on the subcutaneous microcirculation might be brought about by peripheral vasodilation reflected by increased parasympathetic and decreased sympathetic activity, and the artificial CO(2) foot bathing is clinically effective on salvage of CLI (Fontaine stage IV) limbs.

Adult↗

PubMed2001

Successful laparoscopic fundoplication in children with ventriculoperitoneal shunts.

We reported successful laparoscopic fundoplication in 2 pediatric cases with VPS and discuss the safety and feasibility of the procedure. Case 1: A 13-year-old girl with VPS underwent laparoscopic fundoplication. Case 2: a 9-year-old boy with VPS underwent laparoscopic fundoplication. In both cases, laparoscopic Nissen fundoplication was performed with a standard five-port technique with a low pressure of a pneumoperitoneum. The VPS system had no effect on port layout and intraabdominal manipulation and no adverse complications were observed in either case. The effect of a pneumoperitoneum in the VPS system remains controversial, however, the author emphasized that advanced laparoscopic surgery can be performed safely with creating a low pressure of a pneumoperitoneum.

Adolescent↗

PubMed2001

The noradrenaline-dopamine interaction in the rat medial prefrontal cortex studied by multi-probe microdialysis.

Multi-probe microdialysis was used to investigate the interaction between the release of noradrenaline and dopamine in the medial prefrontal cortex. Retrograde microdialysis was used to stimulate or inhibit the activity of the locus coeruleus for a restricted period of time, and the response of extracellular noradrenaline and dopamine in the ipsilateral and contralateral medial prefrontal cortex was recorded with microdialysis probes. Infusion of clonidine into the locus coeruleus (100 microM for 45 min) suppressed noradrenaline release and slightly inhibited dopamine release in the ipsilateral medial prefrontal cortex. Application of carbachol to the locus coeruleus (100 microM for 45 min) stimulated both the noradrenaline and dopamine release in the ipsilateral medial prefrontal cortex. No changes were seen in the contralateral medial prefrontal cortex. In the ipsilateral nucleus accumbens, extracellular noradrenaline levels increased, but dopamine levels remained unchanged. Application to the locus coeruleus (during 10 min) of the glutamate receptor agonists N-methyl-D-aspartate (NMDA) (300 microM) or kainate (100 microM) strongly increased extracellular noradrenaline and dopamine levels in the ipsilateral medial prefrontal cortex. However, in the contralateral probe the release of dopamine (but not of noradrenaline) was also stimulated. Application of carbachol to the locus coeruleus was used as a model to further investigate the presumed noradrenaline-dopamine interaction. In a series of dual-probe experiments, alpha(1)-, alpha(2)-, and beta-adrenoceptor antagonists (prazosin, idazoxan, propranolol) or a reuptake-inhibitor (nomifensine) was administered during carbachol stimulation of the locus coeruleus. Prazosin and propranolol were administered systemically in a dose of 3 mg/kg, whereas idazoxan (10 microM) and nomifensine (100 microM) were infused into the medial prefrontal cortex. However, none of these pretreatments modified the effects of the control carbachol-infusions. The results did not identify a receptor-interaction or a common reuptake site that explained the presumed interaction between dopamine and noradrenaline in the medial prefrontal cortex. Therefore, the noradrenaline-dopamine interaction hypothesis could not be confirmed or refuted.

Adrenergic beta-Antagonists↗

PubMed2001

Both the conserved and the unique gene structure of stomach-specific calpains reveal processes of calpain gene evolution.

The proteins nCL-2 and nCL-2' are members of the Ca2+-dependent cysteine protease (calpain) superfamily, with stomach-specific expression. Like other typical calpains, nCL-2 has three distinct domains, a protease, a C2-like, and a 5EF-hand Ca2+-binding domain, as well as the N-terminal propeptide region. On the other hand, nCL-2' lacks the C2-like and 5EF-hand domains but is otherwise identical to nCL-2, except for the three C-terminal residues. To examine the stomach-specific and presumed alternative expression mechanisms of nCL-2 and nCL-2', we have cloned and characterized the mouse gene for nCL-2 and nCL-2'. The mouse nCL-2 gene contains at least 23 exons, spanning more than 50 kb, and possesses an exon specific for nCL-2' in the middle. Therefore, nCL-2 and nCL-2' are generated by alternative splicing of the same gene, Capn8. Capn8 shows the highly conserved gene organization of the other typical calpain large subunit genes, CAPN1, CAPN2, CAPN3, CAPN9, CAPN11, and Capn12, except for the unique exon between exon 9 and exon 10 of Capn8, which encodes the 3' half of the nCL-2' transcript. No such exon in the corresponding regions was found in CAPN1, CAPN2, CAPN3, CAPN9, or CAPN11. Gene and cDNA structures of a presumed human orthologue of mouse nCL-2, CAPN8, were determined, revealing that it overlaps human CAPN2, the gene for the m-calpain large subunit, in head-to-head orientation at 1q32-41. These features of Capn8 and CAPN8 illustrate a process of calpain gene evolution, i.e., the protease, C2-like, and 5EF-hand domains presumably functioned as independent genes, and the calpain superfamily has evolved by ordered fusions of these ancestral gene units, with subsequent amplifications.

Alternative Splicing↗

PubMed2001

Relationship between antifreeze protein and freezing resistance in Pseudomonas putida GR12-2.

Following transposon Tn5 mutagenesis of the plant growth-promoting rhizobacterium Pseudomonas putida GR12-2, mutants that have different freeze-resistant properties were selected. Five of the freeze-sensitive mutants, i.e. FSM-5, -6, -14, -29, and -41, secreted a lower amount of antifreeze protein-(AFP) into the culture broth compared with the wild-type. Among of these five mutants, the three mutants (FSM-6, FSM-14, and FSM-41) that have the lowest level of freezing resistance (4.0-6.0% survival) also produce AFP at low levels (0.5-0.9 microg/mL) compared with the wild-type (4.8 microg/ml). The antifreeze and ice-nucleating activities of the AFP from these three mutant strains were similar to those of wild-type. Furthermore, the decreased freezing resistance from three mutants could be partially restored by adding purified AFP to mutant cell suspensions. Freezing resistance of three mutants was found to increase in proportion to the addition of AFP up to a concentration of 50 microg/mL. We conclude that accumulation of AFP is one component of the mechanism for freezing resistance in bacteria.

Antifreeze Proteins↗