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Biomedical subjects

T Asai

Publications and source records attributed to T Asai.

At least 127 records · Page 7Linked to original sources
PubMed2000

The beta(2)-adrenergic receptor delivers an antiapoptotic signal to cardiac myocytes through G(i)-dependent coupling to phosphatidylinositol 3'-kinase.

Recent studies have shown that chronic beta-adrenergic receptor (beta-AR) stimulation alters cardiac myocyte survival in a receptor subtype-specific manner. We examined the effect of selective beta(1)- and beta(2)-AR subtype stimulation on apoptosis induced by hypoxia or H(2)O(2) in rat neonatal cardiac myocytes. Although neither beta(1)- nor beta(2)-AR stimulation had any significant effect on the basal level of apoptosis, selective beta(2)-AR stimulation protected myocytes from apoptosis. beta(2)-AR stimulation markedly increased mitogen-activated protein kinase/extracellular signal-regulated protein kinase (MAPK/ERK) activation as well as phosphatidylinositol-3'-kinase (PI-3K) activity and Akt/protein kinase B phosphorylation. beta(1)-AR stimulation also markedly increased MAPK/ERK activation but only minimally activated PI-3K and Akt. Pretreatment with pertussis toxin blocked beta(2)-AR-mediated protection from apoptosis as well as the beta(2)-AR-stimulated changes in MAPK/ERK, PI-3K, and Akt/protein kinase B. The selective PI-3K inhibitor, LY 294002, also blocked beta(2)-AR-mediated protection, whereas inhibition of MAPK/ERK activation at an inhibitor concentration that blocked agonist-induced activation but not the basal level of activation had no effect on beta(2)-AR-mediated protection. These findings demonstrate that beta(2)-ARs activate a PI-3K-dependent, pertussis toxin-sensitive signaling pathway in cardiac myocytes that is required for protection from apoptosis-inducing stimuli often associated with ischemic stress.

Apoptosis↗
PubMed2000

Activation of MMP-2 by Clostridium difficile toxin B in bovine smooth muscle cells.

Matrix metalloproteinase-2 (MMP-2) plays critical roles in cell migration through the breakdown of the extracellular matrix. Cell movements require dynamic actin reorganization, which is controlled by Rho family GTPases. In order to examine the relation between MMP-2 regulation and actin reorganization, we used several inhibitors of Rho family GTPases. Treatment of smooth muscle cells with Clostridium difficile toxin B known to inactivate Rho family GTPases activated MMP-2. However, neither C3 transferase, a Rho inhibitor, nor Y-27632, a specific inhibitor of Rho-kinase, induced MMP-2 activation. Treatment with C3 transferase and Y-27632 caused morphological changes into the round and stellate shape, respectively, by inhibition of actin stress fiber formation. In addition, toxin B treatment induced expression and processing of MT1-MMP, a major activator of MMP-2. Taken together, we suggest the involvement of Rho family GTPases, although inhibition of neither Rho nor Rho-kinase is sufficient, in the activation of MMP-2 through expression and activation of MT1-MMP.

ADP Ribose Transferases↗
PubMed2000

Acetylation of GATA-3 affects T-cell survival and homing to secondary lymphoid organs.

Acetylation of a transcription factor has recently been shown to play a significant role in gene regulation. Here we show that GATA-3 is acetylated in T cells and that a mutation introduced into amino acids 305-307 (KRR-GATA3) creates local hypoacetylation in GATA-3. Remarkably, KRR-GATA3 possesses the most potent suppressive effect when compared with other mutants that are disrupted in putative acetylation targets. Expressing this mutant in peripheral T cells results in defective T-cell homing to systemic lymphnodes, and prolonged T-cell survival after activation. These findings have significant implications in that the acetylation state of GATA-3 affects its physiological function in the immune system and, more importantly, provides evidence for the novel role of GATA-3 in T-cell survival and homing to secondary lymphoid organs.

Acetylation↗
PubMed2000

Cytological and immunological changes in bronchoalveolar lavage fluid and histological observation of lung lesions in pigs immunized with Mycoplasma hyopneumoniae inactivated vaccine prepared from broth culture supernate.

We have compared the cytology of bronchoalveolar lavage fluid (BALF) and the pathology of lung lesions in pigs immunized with/without Mycoplasma hyopneumoniae inactivated vaccine prepared from broth culture supernate on experimental infection. Numbers of total cells, macrophages, neutrophils and lymphocytes have decreased in BALF of vaccinated pigs following infection. The mean percentage of lung lesions, inflammatory cell infiltration into the airways and T cells accumulation around the bronchi were reduced in vaccinated pigs. The levels of tumor necrosis factor (TNF)-alpha also decreased in vaccinated pigs. These results suggest that the vaccination may contribute to decrease TNF-alpha production, and therefore, inflammatory cell responses in the lung due to M. hyopneumoniae infection were suppressed, resulting in fewer lung lesions.

Animals↗
PubMed2000

Suppression of GD1alpha ganglioside-mediated tumor metastasis by liposomalized WHW-peptide.

GD1alpha ganglioside-replica peptides were recently isolated from a phage-displayed random pentadecapeptide library by assaying for inhibition of adhesion of RAW117-H10 lymphosarcoma cells to hepatic sinusoidal microvessel endothelial (HSE) cells. We show here that the Trp-His-Trp (WHW) peptide was identified as a minimal sequence of the GD1alpha-replica peptide WHWRHRIPLQLAAGR. The addition of WHW peptide-attached liposomes displayed efficient inhibition of liver metastasis of RAW117-H10 cells as well as of GD1alpha-mediated adhesion of RAW117-H10 cells to HSE cells in vitro. These results suggest that engineered liposomes for peptide delivery are applicable to treatment for metastasis.

Amino Acid Sequence↗
PubMed2000

Difference in nature of ruptured and unruptured cerebral aneurysms.

Although small aneurysms have an extremely low probability of rupture, most aneurysms that rupture are found to be less than 10 mm in diameter. Histological study of aneurysms and epidemiological analysis of subarachnoid haemorrhage revealed that ruptured and unruptured aneurysms are of a different nature.

Aneurysm, Ruptured↗
PubMed2000

Intubating laryngeal mask for fibreoptic intubation--particularly useful during neck stabilization.

PURPOSE: To assess the ease of fibrescope-assisted tracheal intubation while the patient's head and neck were placed in the neutral or the manual in-line position, and to determine if the intubating laryngeal mask facilitated fibreoptic intubation in these positions. METHODS: In 84 patients, the patient's head and neck were placed in the neutral position (pillow placed under occiput), and in another 40 patients the head and neck were stabilized by the manual in-line method (no pillows under occiput). In both groups, after induction of anesthesia with 2.0-2.5 mgxkg(-1) propofol, 50-100 microg fentanyl and 1.0 mgxkg(-1) vecuronium, patients were allocated randomly into two groups: in Group C tracheal intubation was attempted using only a fibrescope, whereas in Group L fibreoptic intubation through the intubating laryngeal mask was attempted. RESULTS: In group C the success rate of fibreoptic tracheal intubation within two minutes was higher in the neutral position (31 of 42 patients (73%)) than in the manual in-line position (8 of 20 patients (40%)). In contrast, in group L the success rate was similar between the two positions. Tracheal intubation was easier in group L than in group C (P < 0.01 or 0.001) and the time for intubation was shorter in group L than in group C in both head and neck positions. CONCLUSIONS: Fibreoptic tracheal intubation was more difficult in the manual in-line position than in the neutral position. The intubating laryngeal mask facilitated fibreoptic intubation in both positions.

Anesthesia, Inhalation↗
PubMed2000

Failed tracheal intubation using a laryngoscope and intubating laryngeal mask.

PURPOSE: To report unexpected failed tracheal intubation using a laryngoscope and an intubating laryngeal mask, and difficult ventilation via a facemask, laryngeal mask and intubating laryngeal mask, in a patient with an unrecognized lingual tonsillar hypertrophy. CLINICAL FEATURES: A 63-yr-old woman, who had undergone clipping of an aneurysm seven weeks previously, was scheduled for ventriculo-peritoneal shunt. At the previous surgery, there had been no difficulty in ventilation or in tracheal intubation. Her trachea remained intubated nasally for 11 days after surgery. Preoperatively, her consciousness was impaired. There were no restrictions in head and neck movements or mouth opening. The thyromental distance was 7 cm. After induction of anesthesia, manual ventilation via a facemask with a Guedel airway was suboptimal and the chest expanded insufficiently. At laryngoscopy using a Macintosh or McCoy device, only the tip of the epiglottis, but not the glottis, could be seen, and tracheal intubation failed. There was a partial obstruction during manual ventilation through either the intubating laryngeal mask or conventional laryngeal mask; intubation through each device failed. Digital examination of the pharynx, after removal of the laryngeal mask, indicated a mass occupying the vallecula. Lingual tonsillar hypertrophy (1 x 1 x 2 cm) was found to be the cause of the failure. Awake fibrescope-aided tracheal intubation was accomplished. CONCLUSIONS: Unexpected lingual tonsillar hypertrophy can cause both ventilation and tracheal intubation difficult, and neither the laryngeal mask nor intubating laryngeal mask may be helpful in the circumstances.

Anesthesia, Inhalation↗
PubMed2000

Evaluation of serodiagnosis of toxoplasmosis by using the recombinant nucleoside triphosphate hydrolase isoforms expressed in Escherichia coli.

The nucleoside triphosphate hydrolase (NTPase) isoforms termed, NTPase-I and NTPase-II of Toxoplasma gondii, were expressed in Escherichia coli as inclusion bodies and purified under denaturing condition. Furthermore, NTPase-I was refolded as an active form and purified under non-denaturing condition. The purified NTPase isoforms, both denatured and refolded, were tested for their usefulness as antigens for the serodiagnosis of acute toxoplasmosis in immunocompetent humans. The test was conducted by using the recombinant NTPase isoforms and comparing the enzyme linked immunosorbent assay (ELISA) absorbances with the Sabin-Feldman dye test titer. Seventy-three sera from dye test-positive patients, and 30 sera from subjects with no T. gondii infection were examined. The total positive rates in dye test positive sera were: 82% (60/73) for denatured NTPase-I; 78% (57/73) for denatured NTPase-II; and 63% (46/73) for refolded NTPase-I. For all three antigen types of recombinant NTPase, the positive rates of sera of acute toxoplasmosis suspected patients were 93% (13/14). A moderate correlation between the ELISA absorbance using these antigens and the dye test titer was observed with the correlation coefficients, 0.583 (r2) for denatured NTPase-I, 0.472 (r2) for denatured NTPase-II, and 0.604 (r2) for refolded NTPase-I in the linear regression analysis. There was no significant difference observed in the antigenicity between refolded and denatured NTPase-I, nor between the isoforms.

Acid Anhydride Hydrolases↗
PubMed2000

Ease of tracheal intubation through the intubating laryngeal mask during manual in-line head and neck stabilisation.

We studied 40 anaesthetised and paralysed patients, in a randomised manner, to compare the ease of tracheal intubation either using a Macintosh laryngoscope and gum elastic bougie (group C) with the ease of tracheal intubation through the intubating laryngeal mask using a fibreoptic bronchoscope (group L), during manual in-line stabilisation of the patient's head and neck. In both groups, a maximum of 120 s was allowed for attempts at tracheal intubation. The ease of placement of the intubating laryngeal mask or tracheal intubation was assessed using a 100-mm visual analogue scale (VAS). In patients in whom tracheal intubation succeeded, time for intubation was measured. The intubating laryngeal mask was placed successfully in 19 of 20 patients, with the median VAS of 18 mm (95% CI: 13-32 mm). The success rate of tracheal intubation in group L (17 patients) was significantly higher than in group C (nine patients) (p < 0.01), tracheal intubation in group L was significantly easier than intubation in group C (p < 0.001; 95% CI for difference in VAS: 18-68 mm) and time taken for tracheal intubation was significantly shorter in group L than in group C (95% CI for difference: 8-50 s).

Adult↗
PubMed2000

Cremasteric reflex test as an objective indicator of spinal anaesthesia.

We studied 100 men who were scheduled for urological surgery (Group 1) and another 50 men for orthopaedic surgery (Group 2). We attempted to anaesthetise both sides of the lower body in Group 1 and to anaesthetise one leg in Group 2 by injecting 0.3% hyperbaric dibucaine intrathecally. The presence or absence of the cremasteric reflex and loss of sensation to pinprick higher than the first lumbar dermatome were examined by two researchers who were blind to each other's results. In Group 1, both the reflex and the pinprick sensation were always absent bilaterally 5 min after intrathecal injection. In Group 2, in 23 of 50 patients the reflex had become absent bilaterally; in all these patients, bilateral sensory loss was detected. In the remaining 27 patients, both the reflex and the pinprick sensation were absent on the operation side, whereas both were present on the nonoperation side. Sensitivity, specificity and positive or negative predictive value for the cremasteric reflex were all 100%. Disappearance of the cremasteric reflex is a simple objective indicator of spinal anaesthesia at the first lumbar dermatome. This test may be useful in patients who cannot give reliable answers to conventional tests, such as the pinprick test.

Adult↗
PubMed2000

Efficacy of the laryngeal tube during intermittent positive-pressure ventilation.

We studied the efficacy of the laryngeal tube (VBM, Germany) during intermittent positive-pressure ventilation in 50 patients. After induction of anaesthesia and neuromuscular blockade, a size 4 laryngeal tube was inserted for patients of height 155 cm or greater. After insertion of the laryngeal tube, its pharyngeal and oesophageal balloons were inflated to an intracuff pressure of 60 cmH(2)O. An Ambu self-inflating bag was attached to the laryngeal tube and the lungs were ventilated manually at 15 breath.min(-1). It was possible to ventilate the lungs at the first attempt in 47 patients (94%). The airway pressure at which air leaked around the laryngeal tube exceeded 18 cmH(2)O in 41 patients (82%), and was > 30 cmH(2)O in 25 (50%). Median [interquartile range (range)] leak pressure was 30 [20-30 (6 to > 30)] cmH(2)O. Median [interquartile range (range)] tidal volume was 587 [533-653 (133-800)] ml or 8.8 [8.2-10.6 (1.9-12.6)] ml.kg(-1). We conclude that the laryngeal tube has a potential role in airway management during intermittent positive-pressure ventilation for anaesthesia or cardiopulmonary resuscitation.

Adult↗