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Biomedical subjects

Koichi Kobayashi

Publications and source records attributed to Koichi Kobayashi.

At least 73 records · Page 4Linked to original sources
PubMed2003

Conventional detection method of fibrinogen and fibrin degradation products using latex piezoelectric immunoassay.

We developed a conventional immunosensor for fibrinogen and fibrin degradation products (FDP) to combine a quartz crystal microbalance (QCM) with the agglutination reaction of immunized latex beads. FDP induced an immunoreaction due to anti-FDP antibody immobilized latex particles. We successfully measured FDP concentration of in human serum within 10 min by QCM method. The detection range of QCM immunosensor is covered with screening concentration of FDP in serum (<10 microg/ml of FDP). The time course of latex agglutination obtained from QCM immunosensor is synchronized to that of latex photometric immunoassay. SEM was used to observe the surface of QCM that applied FDP serum. The size of latex particles agglutinated on the QCM electrode increased concomitant with FDP concentration. Frequency shift on immunoreaction explains the increased adsorption amount of agglutinated latex on QCM.

Biosensing Techniques↗
PubMed2003

Expression and activity of matrix metallo proteinases 2 and 9 and their inhibitors in rat lungs during the perinatal period and in diaphragmatic hernia.

During lung development, the extracellular matrix undergoes dynamic remodeling. Matrix metalloproteinases (MMPs), and tissue inhibitors of matrix metalloproteinases (TIMPs), are important enzymes that participate in regulating tissue remodeling. There is an abnormal balance of the synthesis and degradation of collagen and elastin in perinatal lung associated with congenital diaphragmatic hernia (CDH). This study was designed to (1) determine the expression and gelatinolytic activity patterns of MMPs 2 and 9 and TIMPs 1 and 2 in rat lungs during the perinatal period, and (2) to test the hypothesis that they are abnormal in nitrofen-induced CDH. Measurements were made using reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting, and zymography. The mRNA expression and activity of MMP 2 did not change significantly from embryonic day 16 to postnatal day 14. The most striking feature found was the rapid increase in the expression of MMP 9 soon after birth. Measurements were repeated on lung tissue isolated from embryonic rats with nitrofen-induced CDH. The expression and activity of MMPs and TIMPs were similar to control values and thus we conclude that these proteins appear not to be responsible for the altered extracellular matrix and morphological abnormalities noted in CDH lungs at birth.

Animals↗
PubMed2003

Respiratory flow in a realistic tracheostenosis model.

The possible mechanism of wheeze generation in tracheostenosis was identified by measuring inspiratory and expiratory flow in a "morphological and distensible" realistic tracheostenosis model. The shape of the model was based on CT (Computed Tomography) images of a patient that had tracheostenosis. A trachea consists of tracheal cartilage rings and smooth muscle. Spatial variation of wall distensibility was achieved in the model by varying the wall thickness based on the elastic modulus measured in pig airways. The spatial variation influenced the flow in the airway and the turbulence production rate decreased faster at smooth muscles. Using the model, we investigated the mechanism of wheeze generation by focusing on the turbulence intensity. The turbulence intensity in expiratory flow was about twice that in inspiratory flow, and larger vortices existed in post-stenosis in expiratory flow, and thus might contribute to wheeze generation.

Animals↗
PubMed2003

Pretreatment of serum containing hemoglobin vesicles (oxygen carriers) to prevent their interference in laboratory tests.

Hemoglobin vesicles (HbV, diameter: 251 +/- 81 nm) are artificial oxygen (O2) carriers encapsulating concentrated hemoglobin (Hb) solution with phospholipid bilayer membrane, and their O2 transporting ability in vivo has been extensively studied. It is important to clarify the interference of the HbV suspension in clinical laboratory tests performed on serum and to establish a pretreatment method to avoid such an interference. The HbV suspension, acellular Hb solution ([Hb] = 10 g/dl) or saline, was mixed with a pooled human serum at various ratios up to 50 vol% ([Hb] = 5 g/dl), and the magnitude of the interference effect of HbV and Hb on 30 analytes was studied. The mixture of the HbV suspension and serum was ultracentrifuged (50,000 g, 20 min) to remove the HbV particles as precipitate, and the supernatant was analyzed and compared with the saline control group. The HbV particles were also removed by centrifugation (2,700 g, 30 min) in the presence of dextran (Mw 200 kDa). The HbV suspension showed considerable interference effects in most analytes. The majority of these effects was more serious than those of the acellular Hb solution. These findings are thought to be due to the light absorption of Hb in HbV and/or the light scattering generated in the suspension that interferes with the colorimetric and turbidimetric measurements. The components of HbV may also interfere with the chemical reactions of the studied assays. However, removal of the HbV from the supernatant diminished the interference in most of the assays: this is an advantage of HbV in comparison with acellular chemically modified Hb solutions.

Blood Substitutes↗
PubMed2003

[Stenting of central airways].

Tracheobronchial stenosis causes severe symptoms such as stridor or dyspnea. Patients who experience these symptoms with inoperable lesions require treatment for palliation of symptoms. In our institution, airway stent placements were performed in 88 patients. The clinical results of stenting for stenosis of the central airways are satisfactory for improvement of the quality of life. Insertion of airway stents and esophageal tubes could improve dysphagia and dyspnea in patients with esophagotracheal fistulas. Recently, several types of prostheses have become available for stenting of airways and each stent has specific features. Therefore it is important for effective and safe stenting to select the type of stent suitable for the condition of each patient.

Adult↗
PubMed2003

The modifier subunit of glutamate cysteine ligase (GCLM) is a molecular target for amelioration of cisplatin resistance in lung cancer.

It is unclear whether a subunit of glutamate cysteine ligase [a modifier subunit (GCLM) and a catalytic subunit (GCLC)] is an effective target for ameliorating cisplatin (CDDP)-resistance. We inhibited each subunit of GCL mRNA using a specific ribozyme (M-Rz and C-Rz) in the pulmonary adenocarcinoma cell line A549. GCL activity was suppressed by the ribozyme. CDDP-resistance was more effectively ameliorated when GCLM rather than GCLC was inhibited. GCLM is a potentially more effective pharmacologic target for ameliorating CDDP-resistance in non-small cell lung cancer than GCLC.

Antineoplastic Agents↗
PubMed2003

[Pathophysiology and treatment of postoperative acute respiratory disturbance].

One major concern after surgery is postoperative pulmonary complications such as atelectasis, aspiration, pneumonia, and respiratory failure. Progress in preoperative and postoperative rehabilitation, in systemic management including respiratory management, and progress in understanding the pathophysiology of acute respiratory failure have improved prevention and the outcome of treatment. However, some conditions remain very difficult to treat, like respiratory failure accompanied by infection or multiple organ failure. In the 1960s, the concept of acute respiratory distress syndrome or adult respiratory distress syndrome was postulated. Tremendous amounts of basic and clinical research have been done to clarify the pathophysiology of and to establish treatment modalities for acute respiratory failure. Our understanding of acute respiratory failure has progressed from the role of microembolism syndrome to cellular components such as neutrophils and platelets and then to humoral factors such as endotoxins, complement factors, and numerous cytokines. In this article, the pathophysiology of acute lung injury and its diagnostic criteria, treatment modalities such as respirator management to protect lung tissue from barotrama and volutrauma by yielding hypercapnea (permissive hypercapnea), drug therapy with neutrophil elastase inhibitor, mechanical support using extracorporeal membrane oxygenation, liquid ventilation, continuous hemodiafiltration, and endotoxin elimination columns are discussed. Early diagnosis and early treatment are mandatory to improve survival in patients with acute respiratory failure, although we have not yet fully understood the pathophysiology of this disease entity sufficiently.

Acute Disease↗
PubMed2002

IRAK-M is a negative regulator of Toll-like receptor signaling.

Toll-like receptors (TLRs) detect microorganisms and protect multicellular organisms from infection. TLRs transduce their signals through MyD88 and the serine/threonine kinase IRAK. The IRAK family consists of two active kinases, IRAK and IRAK-4, and two inactive kinases, IRAK-2 and IRAK-M. IRAK-M expression is restricted to monocytes/macrophages, whereas other IRAKs are ubiquitous. We show here that IRAK-M is induced upon TLR stimulation and negatively regulates TLR signaling. IRAK-M prevented dissociation of IRAK and IRAK-4 from MyD88 and formation of IRAK-TRAF6 complexes. IRAK-M(-/-) cells exhibited increased cytokine production upon TLR/IL-1 stimulation and bacterial challenge, and IRAK-M(-/-) mice showed increased inflammatory responses to bacterial infection. Endotoxin tolerance, a protection mechanism against endotoxin shock, was significantly reduced in IRAK-M(-/-) cells. Thus, IRAK-M regulates TLR signaling and innate immune homeostasis.

Adaptor Proteins, Signal Transducing↗
PubMed2002

RICK/Rip2/CARDIAK mediates signalling for receptors of the innate and adaptive immune systems.

The immune system consists of two evolutionarily different but closely related responses, innate immunity and adaptive immunity. Each of these responses has characteristic receptors-Toll-like receptors (TLRs) for innate immunity and antigen-specific receptors for adaptive immunity. Here we show that the caspase recruitment domain (CARD)-containing serine/threonine kinase Rip2 (also known as RICK, CARDIAK, CCK and Ripk2) transduces signals from receptors of both immune responses. Rip2 was recruited to TLR2 signalling complexes after ligand stimulation. Moreover, cytokine production in Rip2-deficient cells was reduced on stimulation of TLRs with lipopolysaccharide, peptidoglycan and double-stranded RNA, but not with bacterial DNA, indicating that Rip2 is downstream of TLR2/3/4 but not TLR9. Rip2-deficient cells were also hyporesponsive to signalling through interleukin (IL)-1 and IL-18 receptors, and deficient for signalling through Nod proteins-molecules also implicated in the innate immune response. Furthermore, Rip2-deficient T cells showed severely reduced NF-kappaB activation, IL-2 production and proliferation on T-cell-receptor (TCR) engagement, and impaired differentiation to T-helper subtype 1 (TH1) cells, indicating that Rip2 is required for optimal TCR signalling and T-cell differentiation. Rip2 is therefore a signal transducer and integrator of signals for both the innate and adaptive immune systems.

Adaptor Proteins, Signal Transducing↗
PubMed2002

Enhanced expression of telomerase activity in thymoma and thymic carcinoma tissues: a clinicopathologic study.

BACKGROUND: Telomerase is a nucleoprotein complex that caps the physical termini of all eukaryotic chromosomes. Because most malignant cells and reproductive cells have telomerase activity, which elongates telomeric DNA, telomerase may play important roles in unlimited cell division acquisition of the malignant phenotype. The current study examined the relation of telomerase activity in thymoma and thymic carcinoma with the clinicopathologic features of these lesions. METHODS: Tissue specimens were surgically resected from patients with thymoma and thymic carcinoma. Telomerase activity was evaluated according to a modified telomeric repeat amplification protocol assay. Paraffin sections of tumor were immunostained by MIC2 antibody, a marker of immature T cells. RESULTS: Telomerase activity was detected in all thymic epithelial tumors. The activity (mean +/- SD; unit per microg protein) in thymoma (n = 17) was significantly higher than that in thymic carcinoma (n = 7) (431.8 +/- 400.1 vs. 68.8 +/- 39.8; P < 0.01). Telomerase activities in thymoma and thymic carcinoma were significantly higher than that in primary lung adenocarcinoma (33.5 +/- 39.2, n = 47), studied as a control (P < 0.01). In patients with thymoma, telomerase activity did not correlate with tumor stage according to Masaoka classification (P = 0.776). In patients with thymic carcinoma, however, telomerase activity positively correlated with tumor stage (P = 0.02). In thymoma, telomerase activity positively correlated with the ratio of induced lymphocytes according to Rosai's classification (P = 0.045). MIC2-positive lymphocytes were identified in all cases of thymoma (n = 12). In contrast, lymphocytes infiltrating thymic carcinoma did not react with MIC2. CONCLUSIONS: In thymoma, telomerase activity reflects the presence of immature T-cell lymphocytes in tumor tissue rather than tumor stage or malignant phenotype. In thymic carcinoma, telomerase activity derived directly from cancer cells may relate to tumor stage.

12E7 Antigen↗
PubMed2002

Frequency of transmission of human parvovirus B19 infection by fibrin sealant used during thoracic surgery.

BACKGROUND: Fibrin sealant is used in many kinds of surgical procedures. Although pasteurization is insufficient to remove human parvovirus (HPV) B19 from this plasma-derived product, the frequency of HPV B19 infection transmitted by its use has never been known. METHODS: Blood samples of 85 patients more than 20 years of age who had undergone pulmonary resection with fibrin sealant were obtained before and 12, 24, and 48 weeks after surgery. Anti-HPV B19 antibody IgG (HPV B19 IgG) and HPV B19 DNA were detected with these samples. RESULTS: In 56 (65.9%) of 85 patients, blood samples obtained before operation were positive for HPV B19 IgG. In these 56 patients, blood samples obtained 12 to 48 weeks after surgery were all negative for HPV B19 DNA by polymerase chain reaction (PCR). In 6 (20.7%) of 29 patients whose blood samples were negative for HPV B19 IgG before surgery, blood samples obtained 12 to 48 weeks after surgery were positive for HPV B19 DNA by PCR and also positive for HPV B19 IgG. In 5 of these 6 patients reticulocyte counts decreased to less than 10 x 10(9)/l 12 to 20 days after surgery. CONCLUSIONS: Epidemiologic evidence suggests that more than 20% uninfected persons were subsequently infected with HPV B19 by use of fibrin sealant during surgery.

Adult↗
PubMed2002

Overexpression of TIAP/m-survivin in thymocytes enhances cell proliferation.

TIAP/m-survivin, a member of the inhibitor of apoptosis (IAP) protein family, is expressed in a cell cycle dependent manner. It is strongly expressed in various subsets of thymocytes. To investigate a role of TIAP/m-survivin in thymocytes, mice carrying the lck-TIAP transgene were established. Two out of six transgenic mice expressed large amounts of TIAP mRNA and protein in thymocytes. Although T cell development and apoptosis of thymocytes were largely unaffected in lck-TIAP mice, transgenic thymocytes displayed hyperproliferation in response to PMA and ionomycin but not to anti-CD3 antibody. Thus, overexpression of TIAP/m-survivin augments cell proliferation of thymocytes to a certain stimulation.

Animals↗
PubMed2002

[Chemosensitivity test for unresectable non-small cell lung cancer].

To choose the optimal chemotherapy regimens, we have employed a new chemosensitivity testing method, the collagen gel droplet embedded culture drug sensitivity test (CDDST) for patients with non-small cell lung cancer (NSCLC). This method requires fewer cancer cells(1 x 10(5) cells in 2 specimens biopsied by bronchoscopy) than conventional chemosensitivity tests and can be also used to assess cases of malignant effusion. Correlations between the in vitro and in vivo responses were: true positive ratio, 75.0% (21/28 patients); true negative ratio 85.0% (17/20 patients); and accuracy 79.2%. The median survival time (MST) of patients (n = 11) with unresectable NSCLC who were given optimal chemotherapy based on the results of the CDDST was 15.8 months and the MST of those (n = 16) who did not receive a sensitive agent was 5.6 months. There was a significant difference between these two groups (p = 0.0048, log-rank test). These results suggest that the CDDST is an effective method for chemosensitivity testing in unresectable NSCLC.

Antineoplastic Agents↗
PubMedDate not supplied

Hemorrhagic shock resuscitation with an artificial oxygen carrier, hemoglobin vesicle, maintains intestinal perfusion and suppresses the increase in plasma tumor necrosis factor-alpha.

It is known that damage to the intestinal mucosa followed by systemic inflammatory response is one of the leading causes of shock related morbidity and mortality. In this study, we examined the ability of an artificial oxygen carrier hemoglobin vesicle (HbV) to sustain systemic and intestinal perfusion during hemorrhagic shock. In rabbits, hemorrhagic shock (40% of the estimated blood volume) was resuscitated with 5% albumin (alb group), HbV suspended in 5% albumin (HbValb group), or washed red blood cells suspended in 5% albumin (RBCalb group). Plasma tumor necrosis factor (TNF)-alpha level was measured in rats under the same experimental protocol. No significant intergroup differences were seen in systemic hemodynamics. In contrast, parameters of intestinal perfusion significantly deteriorated in the alb group but were equally well sustained in the HbValb and RBCalb groups. Also, a significant increase in plasma TNF-alpha level was seen in the alb group but not in the RBCalb or HbValb groups. These results indicate the proficient oxygen transporting capability of HbV and its potential efficacy in shock resuscitation.

Animals↗