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Biomedical subjects

N Kobayashi

Publications and source records attributed to N Kobayashi.

At least 37 records · Page 2Linked to original sources

[Tracheobronchial injury].

We studied 6 cases of tracheobronchial injury due to the blunt chest truma in our department. All patients were male of 19 to 60 years of age. Injured sites were main bronchus in 2, tracheobronchial portion in 2, cervical trachea and main bronchus in 1, cervical trachea in 1. In a case of cervical tracheal injury and 2 cases of tracheobronchial injury, emergent operation was performed on the day of accident. Other cases with the main bronchial injury underwent conservative treatment at first, but subsequent bronchoplasty was necessary for them due to the bronchial stenosis. After the surgery for 2 cases of tracheobronchial injury, mechanical ventilation with double lumen tube was continued to reduce the airway pressure for the anastomotic sites. In conclusion, early surgical treatment is recommended for the airway injury and the respiratory management using double lumen tube after surgery may be helpful in preventing trouble at the anastomosis.

Adult↗

Strain-induced interference effects on the resonance Raman cross section of carbon nanotubes.

In this Letter, we report the effects of strain on the electronic properties of single-wall carbon nanotubes. When we normalize the electronic transition energies to the corresponding values obtained for unstrained tubes, we obtain that, regardless of the tube diameter, all the data collapse onto universal curves following an n - m = constant family pattern. In the case of metallic tubes, quantum interference effects on the Raman cross section are predicted for strained tubes when the energies of the lower and the upper components have nearly the same values. Experimental evidence for the strain-induced Raman cross section changes is observed in single nanotube spectroscopy.

Journal Article↗

Laparoscopy-assisted distal gastrectomy for early gastric cancer: experience with 111 consecutive patients.

BACKGROUND: Laparoscopy-assisted distal gastrectomy (LADG) is gaining wider acceptance for the treatment of early gastric cancer. However, firm evidence supporting its safety and usefulness is scant, and no study has compared the outcomes of various procedures for LADG. We examined the surgical outcomes of LADG performed using different methods for lymph node dissection. METHODS: Between September 1998 and January 2005, we performed LADG in 111 patients with early gastric cancer. In the 55 patients treated initially, group 2 lymph node dissection was performed through a small, 7-cm-long incision (minilaparotomy). In 43 of these patients, hand-assisted laparoscopic surgery (HALS) was done. In the 56 patients treated more recently, lymph node dissection was performed laparoscopically. In 31 of these patients, the celiac branches of the vagus nerve were preserved. Clinical outcomes of these procedures were compared. RESULTS: In the first 55 patients, HALS significantly shortened the operation time (277 vs 243 min, p < 0.05). In the latter 56 patients, LADG with preservation of the celiac branches of the vagus nerve was associated with a longer operation time (283 vs 228 min, p < 0.01) and higher blood loss (150 vs 92 g, p < 0.05) than with LADG without celiac branch preservation. There were no differences among the various operative procedures in postoperative course, including the length of the postoperative hospital stay or the rate of complications. CONCLUSIONS: LADG is a safe and technically feasible procedure for the treatment of early gastric cancer. Laparoscopic lymph node dissection provided a good visual field and was easier to perform and required less time when the celiac branches of the vagus nerve were not preserved, with no negative effect on outcome.

Aged↗

Comparison of NSP4 protein between group A and B human rotaviruses: detection of novel diarrhea-causing sequences in group B NSP4.

The human group B rotavirus is a causative agent of severe adult diarrhea. In this study, we analyzed the NSP4 structure of a group B rotavirus strain, CAL-1, and determined whether enterotoxin activity was present in CAL-1 NSP4. CAL-1 NSP4 was comprised of 219 amino acids which was longer than group A and C rotavirus NSP4, and the primary structures of their sequences differed considerably. However, CAL-1 NSP4 had an enterotoxin-like sequence (residues 106-127) that was only 27% identical to the enterotoxin region of NSP4 of KUN (a group A rotavirus strain) at residues 114-135. Interestingly, both of the synthetic peptides, one (residues 99-128) containing the enterotoxin-like sequence and the other (residues 191-219) containing 29 C-terminal amino acids of CAL-1 NSP4, induced diarrhea in 5.5-day-old mice, but not in 17.5-day-old mice, when administered parenterally. Thus, rotavirus "enterotoxin" sequences could be considerably divergent.

Age Factors↗

Cyclosporine suppresses cell growth and collagen production in hepatic stellate cells.

BACKGROUND: In HCV-related graft hepatitis, immunosuppression has been implicated in rapid progression to cirrhosis, a serious clinical issue. We investigated the effects of cyclosporine or tacrolimus on cell growth and collagen production by hepatic stellate cells (HSC), which play a role in hepatic fibrosis. MATERIALS AND METHODS: Cultured rat HSCs and human HSC-derived TWNT-4 cells were evaluated for proliferation, type I collagen, phosphorylation states of mitogen-activated protein kinases extracellular signal-regulated kinase 1/2; [MAPKs Erk1/2], c-Jun N-terminal kinase (JNK, p38), as well as the expression of collagen, matrix metalloproteinase-1 (MMP-1) and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) genes. RESULTS: Cyclosporine suppressed cell growth and collagen production in a concentration-dependent manner. At clinically relevant concentrations of 0.125 micromol (150 ng/mL) cyclosporine significantly reduced collagen production per cell by more than 50%. Similarly, tacrolimus also reduced both collagen concentration and cell number; however, tacrolimus at a clinically relevant concentration of 12.5 nmol (10 ng/mL) did not significantly reduce collagen production. Treatment with cyclosporine reduced type I collagen and TIMP-1 expression and enhanced MMP-1 expression. Cyclosporine also inhibited phosphorylation strongly for JNK and p38, and weakly inhibited for Erk1/2. CONCLUSION: These findings demonstrated that cyclosporine suppresses cell growth and collagen production, suggesting that it may have an antifibrogenic effect.

Animals↗

Polarization of Th1/Th2 in human CD4 T cells separated by CD62L: analysis by transcription factors.

BACKGROUND: T-cell surface antigens that differentiate clearly between Th1 and Th2 have not been identified. Discrimination of Th1/Th2 subpopulations by CD62L expression has been reported. We investigated the expression of transcription factors that regulate Th1/Th2 cytokine synthesis in human CD4+ T-cell subpopulations separated by CD45RO and CD62L, and compared the ratio of CD62L+ to CD62L- cells between healthy individuals and patients with allergic diseases. METHODS: Human peripheral blood samples were obtained from healthy volunteers and patients. CD4+ T cells were isolated by negative selection. Three CD4+ T-cell subpopulations separated by CD45RO and CD62L were isolated using three-color fluorescence. Sorted cells were stimulated with anti-CD3 monoclonal antibody, and the cytokine levels were measured using a Cytometric Bead Array Kit. Transcription factor expression was examined by reverse transcriptase polymerase chain reaction (RT-PCR) and real-time RT-PCR. RESULTS: Interleukin (IL)-4 and IL-5 production levels by CD45RO+CD62L+CD4+ T cells were higher than those of CD45RO+CD62L-CD4+ T cells (P < 0.05), whereas interferon-gamma and tumor necrosis factor-alpha production were lower levels (P < 0.05). T-cell immunoglobulin mucin-3 and T-bet expression were detected in CD45RO-CD62L+ and CD45RO+CD62L- cells following stimulation, but not in CD45RO+CD62L+ cells. However, the ratio of CD62L+ to CD62L- cells was the same in both healthy individuals and patients (P = 0.54). There was no difference in Th1/Th2 cytokine synthesis by CD4+ T cells. CONCLUSION: Analyses of cytokine syntheses and transcription factor expression demonstrated that CD62-negative and -positive subpopulations of human CD45RO+CD4+ T cells represent characteristics of Th1 and Th2, respectively.

CD4-Positive T-Lymphocytes↗

Cavity polaritons in InGaN microcavities at room temperature.

Cavity polaritons are observed in InGaN quantum well (QW) microcavities at room temperature. High-quality microcavities are fabricated by the wafer-bonding of InGaN QW layers and dielectric distributed Bragg reflectors. The anticrossing behavior of strong exciton-photon coupling is confirmed by vacuum-field Rabi splitting obtained from reflection measurements. This strong coupling is also enhanced by increasing the integrated oscillator strength coupled to the cavity mode. The oscillator strength of InGaN QW excitons is 1 order of magnitude larger than that of GaAs QW excitons.

Journal Article↗

Imaging phase separation near the Mott boundary of the correlated organic superconductors kappa-(BEDT-TTF)2X.

Electronic phase separation consisting of the metallic and insulating domains with 50-100 microm in diameter is found in the organic Mott system kappa-[(h8-BEDT-TTF)(1-x)(d8-BEDT-TTF)x]2Cu[N(CN)2]Br by means of scanning microregion infrared spectroscopy using the synchrotron radiation. The phase separation appears below the critical end temperature 35-40 K of the first-order Mott transition. The observation of the macroscopic size of the domains indicates a different class of the intrinsic electronic inhomogeneity from the nanoscale one reported in the inorganic Mott systems such as high-Tc copper and manganese oxides.

Journal Article↗

Bone mineral density of the lumbar spine is associated with TNF gene polymorphisms in early postmenopausal Japanese women.

We investigated the relationships between tumor necrosis factor (TNF) gene polymorphism, circulating TNF-alpha (TNF-alpha) concentrations, and bone mineral density (BMD) in the lumbar spine. TNF gene polymorphisms studied were the Nco I polymorphism within the first intron of TNF-beta (TNF-beta) and three single nucleotide polymorphisms in the promoter region of the TNF-alpha gene, at positions -857, -863, and -1031. Allelic variants of the TNF gene were identified using restriction fragment length polymorphism (RFLP) analysis in 177 postmenopausal Japanese women within 10 years after menopause, aged 56.4 +/- 4.5 years (mean +/- SD). A significantly higher prevalence of the alleles TNF-alpha-863A (20.3% versus 9.9%) and TNF-alpha-1031C (21.3% versus 12.4%) was seen in the low BMD group (Z-score < 0, n = 91) than in the high BMD group (0 < Z-score, n = 86). In genotype analysis, although difference did not reach a significant level, women with the rarest allelic variants, i.e., homozygous TNFbl, TNF-alpha-863A, and TNF-alpha-1031C, showed the lowest BMD Z-scores. Women with another rarest allelic variant, TNF-alpha-857T/T had significantly lower BMD Z-scores than did women with TNF-alpha-857C/T or -857C/C. The BMD Z-score decreased significantly with an increase in the total number of such rare alleles. Serum concentrations of TNF-alpha did not differ significantly among groups divided by genotypes. Multiple linear regression analysis revealed that the total number of rare alleles, in addition to the body mass index and the number of years since menopause, was an independent predictor of the BMD. These presumptive functional polymorphisms of the TNF gene may be associated with the lumbar spine BMD in early postmenopausal Japanese women.

Absorptiometry, Photon↗

Transduction of human islets with the lentiviral vector.

Establishment of an efficient gene delivery system for human pancreatic beta cells is important for the development of diabetes-targeted cell therapies. The human immunodeficiency virus type 1 (HIV-1)-derived lentiviral vector is well documented to be an effective gene transfer tool for various types of cells. Thus, we examined the efficiency of lentivirus-mediated gene delivery for human islets. Human islets were isolated using defined protocols for enzymatic dissociation and purification using discontinuous Ficoll gradients with a refrigerated Cobe 2991 machine. Isolated islets were shipped to Japan, cryopreserved for 3 months, and then subjected to transduction. A vesicular stomatitis virus G-protein (VSV-G)-pseudotyped lentiviral vector LtV-NLS/LacZ was produced in 293T cells under the Fugene6 method. 804G extracellular matrices were applied for monolayer formation of islets. Detection of NLS/LacZ expression was performed using X-gal staining. Lentiviral transduction was effective in these monolayer islets.

Cryopreservation↗

Partial hepatectomy and subsequent radiation facilitates engraftment of mouse embryonic stem cells in the liver.

For liver-targeted regenerative medicine, embryonic stem (ES) cell-derived hepatocyte-like cells proffer great expectation. In vitro exposure to a combination of various growth factors, such as hepatocyte growth factor and fibroblast growth factor-4, as well as cytokines, leads to differentiation of ES cells into hepatocyte-like cells. We sought to determine the in vivo environment that allowed engraftment of ES cells transplanted to the liver. Thus, we examined the effect of partial hepatectomy (50%) (PHT) and subsequent radiation (RT) of the male Balb/c mouse host liver on ES cell engraftment. ES cells (5 x 10(6)) derived from 129Sv mice were transplanted into the residual liver. The controls were ES cells transplanted into a normal liver. Bromo-deoxy-residine (BrdU)-uptake was performed to evaluate the effect of hepatectomy and RT on hepatocyte regeneration. Mouse ES cells engrafted, forming teratomas in the normal liver without showing any mononuclear infiltration. A liver modified by PHT and RT facilitated engraftment of mouse ES cells compared with a normal liver. Hepatic RT significantly suppressed hepatocytic uptake of BrdU.

Animals↗

Pulse dye densitometry using indigo carmine is useful for cardiac output measurement, but not for circulating blood volume measurement.

BACKGROUND AND OBJECTIVE: We evaluated the validity of a newly developed pulse dye densitometer for indigo carmine for measuring cardiac output and circulating blood volume. METHODS: Measurements of cardiac output and circulating blood volume were performed with the indigo carmine densitometer during normovolaemia, hypovolaemia and hypervolaemia in nine mongrel dogs under general anaesthesia. The validity was evaluated by comparison of the values of cardiac output and circulating blood volume obtained by the thermodilution technique and the 51Cr-labelled red blood cell method, respectively. We also examined indigo carmine removal by continuous veno-venous haemofiltration after indigo carmine injection. RESULTS: There was good agreement between dye densitometer- and thermodilution-derived cardiac output (r = 0.885, P < 0.001). The bias and limits of agreement of these values were 0.09 and+/-1.07 L min(-1) (2 SD, n 22), respectively. The dye-densitometer-derived circulating blood volume was greater than that of the 51Cr-labelled red blood cell method, and both values showed weak agreement (r = 0.587, P < 0.027). The sieving coefficient of indigo carmine through continuous veno-venous haemofiltration was 0.34+/-0.06. CONCLUSIONS: These data indicate that indigo carmine densitometry is a reliable method for cardiac output determination, but it overestimates circulating blood volume, probably due to the transition of indigo carmine into the extravascular space in the systemic circulation.

Algorithms↗

Mediastinal emphysema and bilateral pneumothoraces with chronic GVHD in patients after allogeneic stem cell transplantation.

It is difficult to treat lung complications caused by chronic graft-versus-host disease (GVHD) after allogeneic stem cell transplantation (allo-SCT). We retrospectively analyzed the characteristics of five patients with mediastinal emphysema (ME) and bilateral pneumothoraces (BP) caused by chronic lung GVHD after allo-SCT. Four of these patients had undergone unrelated SCT, and three had had HLA-identical unrelated donors. All patients received total body irradiation (TBI) during conditioning. Immunosuppressive agents were administered as GHVD prophylaxis, but two patients developed acute GVHD and all the five developed chronic GVHD. The onset of lung complications was 99-1915 days (median, 202 days) after SCT. The onset of ME and BP was 6-48 days (median, 23 days) after the onset of lung complications. Immunosuppressive agents were initially beneficial on the lung complications, but the patients later showed no response to therapy, and all died from respiratory failure 7-195 days (median, 28 days) after the development of ME and BP. The results suggest that these complications progress rapidly, are resistant to treatment, and have a poor prognosis. It is therefore important to start prophylaxis and treatment as early as possible.

Adolescent↗

Reduction of shrinkage on heat-activated acrylic denture base resin obtaining gradual cooling after processing.

Heat-activated acrylic denture base resin is widely used for its many good attributes, although it does show polymerization shrinkage. Although several processing methods have been developed for the purpose of minimizing polymerization shrinkage, some warping after processing is inevitable. The purpose of this study was to examine the development of residual stress relaxation in resin denture base samples in the region where shrinkage was restricted, in order to clarify how cooling variations in the stone mould influenced the shrinkage. Flat, dumbbell-shaped specimens were used. Thermocouples and strain gauges were embedded in the resin for measuring temperature and strain during the dough-stage of resin packing. To clarify stress relaxation in the stone mould, specimens were removed from the stone mould by de-flasking 4 h after the start of cooling at room temperature (control), and 12 and 24 h from the start of gradual cooling in a water bath. The strain differences between before and after removing from the stone mould for the control, and 12- and 24-h experimental groups were 1793, 1354 and 1093 mu epsilon, respectively. Our results suggest that a gradual cooling course for 12 h or more after processing a heat-activated acrylic denture base is effective for lessening deformation of the prosthesis.

Acrylic Resins↗

Simultaneous detection of Staphylococcus aureus and coagulase-negative staphylococci in positive blood cultures by real-time PCR with two fluorescence resonance energy transfer probe sets.

A real-time PCR assay that uses two fluorescence resonance energy transfer probe sets and targets the tuf gene of staphylococci is described here. One probe set detects the Staphylococcus genus, whereas the other probe set is specific for Staphylococcus aureus. One hundred thirty-eight cultured isolates, which contained 41 isolates of staphylococci representing at least nine species, and 100 positive blood cultures that contained gram-positive cocci in clusters were tested. This assay was 100% sensitive and 100% specific for the detection of the Staphylococcus genus and of S. aureus.

Blood↗