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Biomedical subjects

T Asakura

Publications and source records attributed to T Asakura.

At least 127 records · Page 7Linked to original sources
PubMed1997

[Successful emergency surgical management following cardiac massage in a patient with acute myocardial infarction due to total obstruction of the left main trunk].

The prognosis in patients manifesting shock following acute myocardial infarction due to total occlusion of the left main trunk (LMT) is usually very poor and so is the lifesaving rate. Accurate judgement and rapid response are key to the successful management of this disease. We experienced a successful case with emergency coronary artery bypass grafting (CABG) on the 14 the day after initial attack. The patient, who had total occlusion of LMT, underwent a PTCA (percutaneous transluminal coronary angioplasty) during the initial attack under cardiac massage. We think in situations where patients have cardiac arrest, shock, elevated CPK levels suggesting devastation of myocardium due either to LMT or severe triple vessels disease, early catheter intervention rather than emergency CABG would be much more tolerable as long as hemodynamic situation allows. Our previous experience taught us that immediate surgical intervention with CABG usually resulted in poor outcome. Further refinements regarding the surgical procedure, technique, assist circulatory supports, cardioplegia, etc., are indispensable before trying to have a successful emergency CABG.

Angioplasty, Balloon, Coronary↗
PubMed1997

[Coronary artery bypass grafting in a patient with a permanent tracheal stoma].

The performance of open heart surgery in a patient with a tracheostoma can present difficult problems, including mediastinitis and inadequate operative exposure. A 79-year-old man was admitted because of angina pectoris, and had undergone tracheostomy for carcinoma of the larynx 14 years previously. He underwent coronary artery bypass grafting with saphenous vein graft to # 8, 12. A skin incision was made from the angle of Louis to the xiphoid process and carried down through the subcutaneous tissue. The sternum was divided from the xiphoid process to the manubrium and then dislocated from the intact manubrium. Operative time was 165 minutes and arrest time was 64 minutes. Postoperative course was satisfactory and discharged within 24 days after operation. We think that in a case of open heart surgery with a tracheostoma no dissection near a tracheostoma is necessary in order to decrease the risk of postoperative wound infection and mediastinitis.

Aged↗
PubMed1996

Emotional and behavioral correlates of mediodorsal thalamic neurons during associative learning in rats.

Neuronal activity was recorded from the mediodorsal thalamic nucleus (MD) of behaving rats that were trained to lick a protruding spout just after a conditioned stimulus to obtain reward or to avoid shock. Conditioned stimuli included both elemental (auditory or visual stimuli) and configural (simultaneous presentation of auditory and visual stimuli predicting reward outcome opposite that predicted by each stimulus presented alone) stimuli. Of 122 MD neurons responding during the task, the activity of 13 increased just before licking only during the task, but not before spontaneous licking during the intertrial interval (conditioned behavior related). These conditioned behavior-related neurons were located mainly in the lateral MD, which has intimate anatomical connections with motor-related areas such as anterior cingulate and striatum. The activity of the other 109 neurons was related to conditioned stimulation (conditioned stimulus related). Most of these neurons responded differentially to both elemental and configural stimuli in terms of reward contingency, and also changed their responses during extinction and relearning trials. Conditioned stimulus-related neurons with latencies < 300 msec were located mainly in the rostromedial MD, which receives afferents from the basolateral nucleus of the amygdala in which sensory information from various sources converge. Furthermore, most differential neurons that were tested responded during the delay period in a reward task in which a delay was imposed between the conditioned stimulus and reward delivery. The present results, along with previous anatomical studies, suggest the existence of two limbic circuits: anterior cingulate-striatum-lateral MD (motor) and amygdala-medial MD-orbital prefrontal cortex (short-term memory/emotion).

Acoustic Stimulation↗
PubMed1996

The effects of pH on N-methacryloyl glycine primer on bond strength to acid-etched dentin.

To develop a more effective adhesive primer, it is imperative to understand the adhesion mechanisms of the resin to the demineralized dentin through a dentin primer. When the bonding agent was directly applied to the dentin etched by 40 wt % phosphoric acid without a primer pretreatment, the bond strength of the resin to the dentin was 5 MPa. Conversely, when the demineralized dentin was pretreated with the N-methacryloyl glycine (NM alpha A) primer solution with a pH value of 1.5, the bond strength increased considerably to 15 MPa. However, the bond strength dropped dramatically from 15 to 3 MPa when the sodium salt of NM alpha A was added, thereby increasing the pH value of the NM alpha A primer solution from 3.2 to 5.0. When the pH value was increased above 3.5 (pKa value), the number of ionized NM alpha A species increased in the solution. As a result, the bond strength of the resin fell to approximately 3 MPa. This result was obtained despite the 5-micron-thick hybrid layer that was created in the subsurface of the intertubular dentin. The number of unionized NM alpha A species increased by lowering the pH value below 3.5. As a result, the NM alpha A primer provided a higher bond strength of the resin to the demineralized dentin. In contrast, when 10 wt % citric acid containing 3 wt % ferric chloride was applied to the dentin, maximum bond strength was obtained when the pH value of the NM alpha A primer solution was 3.5. The pH dependency of the bond strength obtained following 10 wt % citric acid containing 3 wt % ferric chloride etching is different from the results obtained from 40 wt % phosphoric acid etching. This can be attributed to the difference in the characteristics of the demineralized collageous layer.

Acid Etching, Dental↗
PubMed1996

Speech-induced changes in corticospinal excitability.

The aim of the experiments was to investigate the effects of speech on the excitability of corticospinal pathways to human hand muscles. Single transcranial magnetic stimuli were given randomly over the hand area of either the left or right motor cortex of 10 right-handed and 3 left-handed normal volunteers. Electromyographic responses were recorded in the relaxed first dorsal interosseous muscle while the subjects (a) read aloud a piece of text, (b) read silently, (c) spoke spontaneously, or (d) made sounds without speaking. The only consistent effect across subjects occurred during task a, which significantly increased the size of responses evoked in the dominant hand of all subjects, but had either no effect (8 subjects) or a smaller effect in the nondominant hand. Tasks b and d had no reliable effect, whereas task c tended to increase response size in both hands. Control measurements suggest that the effects in task a were caused by changes in cortical rather than spinal excitability. This is the first demonstration of lateralized speech effects on the excitability of cortical arm areas. The results provide a useful adjunct to other tests of cerebral dominance, using only single- rather than repetitive-pulse cortical stimulation.

Adult↗
PubMed1996

Percentage of reversibly and irreversibly sickled cells are altered by the method of blood drawing and storage conditions.

We previously reported that the percentage of reversibly and irreversibly sickled cells (RSC and ISC, respectively) in the blood of patients with sickle cell disease is strongly influenced by the method of blood drawing (PNAS 91:12589, 1994). We now document the effect of blood storage conditions on the percentage of RSC and ISC. The percentage of RSC was lowest when blood was stored at 0 degree C, while the percentage of RSC was highest in specimens kept at 37 degrees C. At room temperature, the percentage of RSC increased slightly over 8 hours. The percentage of ISC was also temperature dependent and was reduced significantly upon cooling. Our results showed that many ISC reverted to a discoidal shape after 3 hrs of cooling after treatment of blood with oxygen or carbon monoxide. Since no Hb S polymers were detected in ISC treated with oxygen or carbon monoxide, the time required for shape restoration may be attributed to the membrane. We measured ISC levels of 10 patients with consideration of storage temperature and compared the values with those determined by the conventional method and also with those published previously.

Anemia, Sickle Cell↗
PubMed1996

Regulation of pyridoxal-5'-phosphate level by biogenic amines in mouse brain.

We investigated the relationship between the concentration of pyridoxal-5'-phosphate (PLP) and biogenic amine in mouse brain. The production of PLP from pyridoxal (PL) by pyridoxal kinase (PLK) was inhibited by the addition of dopamine (DA), norepinephrine (NE) and 5-hydroxytryptamine (5-HT), but not by that of epinephrine and N-acetyl-serotonin. DA and NE were combined with PLP by a non-enzymatic reaction, whereas 5-HT was bound only slightly with PLP. The conjugated product of PLP with DA was also detected by HPLC analysis when PLK activity was assayed using PL as a substrate in the presence of DA. In an in vivo investigation, the depletion of DA and 5-HT in mouse brain after an intraperitoneal injection of 5 mg/kg reserpine, led to slight elevation of the PLP level to 120% of the control level. By contrast, the increase in DA in the brain caused by intraperitoneal administration of 150 mg/kg L-DOPA caused the PLP concentration to decrease to 70% of the control level. However, no change in PLK activity in the brain was observed when the mice were treated with either reserpine or L-DOPA. These results suggested that the level of PLP in mouse brain was partly regulated by the concentration of biogenic amines, such as DA, NE and 5-HT, without apparent induction of PLK.

Animals↗
PubMed1996

Proximal branching patterns of middle cerebral artery (MCA) in rats and their influence on the infarct size produced by MCA occlusion.

The branching patterns of the proximal middle cerebral artery (MCA) and their influence on the infarct size following MCA occlusion in rats were studied. In the proximal part from the level of the olfactory tract, the MCA most often presented one surface branch extending anteriorly, with a variable number of surface branches extending posteriorly. We classified the branching patterns of the posteriorly extending surface branches as follows: Type 1 (57.5%), one prominent proximal surface branch; Type 2 (30.2%), no prominent branch but two or more small surface branches; and Type 3 (12.3%), no surface branches with a visible junction with the MCA but surface branches probably arising from the internal carotid artery at the origin of the MCA. When the proximal surface branches (especially that in Type 1) remained uncoagulated, the infarct size in both the cortex and striatum was significantly reduced compared with that when coagulation was proximal to the most proximal surface branch. The reduction of cortical and striatal infarct sizes was particularly prominent in the posterior portion. To increase the infarct size and reduce variability, it is suggested that the MCA trunk should be coagulated from the origin to the rhinal fissure including the surface branches.

Animals↗
PubMed1996

Design and synthesis of C-linked fucosides as inhibitors of E-selectin.

Two series of C-linked fucosides as mimetics for the tetrasaccharide sialyl Lewis X have been synthesized and tested as inhibitors of E-Selectin. The fucopeptides have been prepared from three key intermediates, including alpha-C-allyl fucose, natural and unnatural amino acids bearing hydroxyl groups and an alpha, omega-diacid moiety for the imitation of the essential three parts of SLex, i.e., the Fuc, Gal, and NeuAc. The nature and distance of the linkage of the fucose moiety to the amino acids as well as the distance between the amino acids and the terminal carboxylic acid group turned out to be crucial for the biological activity. In addition the necessity of both OH groups (4- and 6-OH) in the Gal part could be confirmed. Conformational NMR study of the most active mimetic supports the structure-activity relationship. A second series of mimetics was prepared, where Fuc and Gal moieties were purely C-linked. In the synthesis of beta-C-allyl galactose an intramolecular 1,2-hydride shift led to an interesting side product. However, the substituted glycosidic oxygens led to a substantial loss of conformational constrain, which could not be compensated and resulted in low activity.

E-Selectin↗
PubMed1996

Pharmacokinetic analysis of protein-conjugated doxorubicin (DXR) and its degraded adducts in DXR-sensitive and -resistant rat hepatoma cells.

After treatment of AH66DR cells with the multidrug resistance (MDR) phenotype with bovine serum albumin (BSA)-conjugated [14C]doxorubicin (DXR), accumulation of the drug in the secondary lysosomal fraction increased as a function of time up to 24 h without any significant increase of the drug in other organellae. By contrast, AH66P cells showed a marked increase in accumulation of the drug in the mitochondrial fraction, and a moderate increase in the lysosomal and nuclear fractions. The intracellular degradation of the internalized conjugate was assessed by HPLC gel filtration as molecular change of the drug. The initial molecular mass (M(r)) of BSA-conjugated [14C]DXR was estimated to be 70 kDa; however, the secondary lysosomal fraction contained mainly three peaks of [14C]compounds ranging from 3 to 70 kDa. The [14C]compound extracted from the nuclear and mitochondrial fractions showed only one peak, which was estimated to be smaller than 2 kDa. By contrast, the cytosolic fraction contained mainly two peaks of [14C]compounds, which were smaller than 2 kDa and larger than 500 kDa. These results indicated that the intracellular distribution of the administered drug, based probably on the drug-traffic mechanism in the cells, was quite different between the two cell lines, but some of the biochemical characteristics of the degraded compounds from each subcellular fraction were similar because the degradation processes in each fraction might be almost identical. The possibility of lysosomal degradation of the protein-conjugated DXR leading to expression of cytotoxicity was also confirmed by the fact that only lysosomal digestable poly-L-lysine-conjugated DXR exhibited dose-dependent cytotoxicity against both cell lines in marked contrast to the cells treated with poly-D-lysine-conjugated DXR. It was concluded that lysosomal breakdown of protein-conjugated DXR, which had been taken up by endocytosis, and the liberation of the degraded active adducts of the conjugate without efflux by the MDR pump mechanism must be an essential stage in the development of the cytotoxicity against tumor cells with or without the MDR phenotype.

Animals↗
PubMed1996

Prognostic significance of Ki-67 labeling index in urothelial tumors of the renal pelvis and ureter.

PURPOSE: We evaluated the prognostic significance of the Ki-67 labeling index in 70 patients with primary urothelial tumors of the renal pelvis and ureter. MATERIALS AND METHODS: Immunohistochemical staining for Ki-67 in archival tumor materials was done by the streptavidin-biotin method. RESULTS: Univariate survival analysis showed that the prognosis of patients with a high Ki-67 labeling index of 21.7 or more was significantly worse than that of patients with an intermediate labeling index of 13.3 to less than 21.7 (p < 0.01) or a low labeling index of less than 13.3 (p < 0.001). Multivariate survival analysis showed that staining for Ki-67 labeling index was significantly correlated with prognosis (p < 0.01). CONCLUSIONS: Analysis of Ki-67 labeling index provides useful prognostic information about patients with primary urothelial tumors of the renal pelvis and ureter.

Antigens, Neoplasm↗
PubMed1996

[Treatment of scrotal hydrocele using fibrin adhesive].

For the purpose of adhesion of the tunica vaginalis in scrotal hydrocele, we used fibrin adhesive, Bolheal. Between September 1993 and December 1994, 13 patients with scrotal hydrocele received occlusion therapies using Bolhead. The therapy was effective in 1 of the 6 patients (17%) administered 2.4 mg of fibrinogen and 750 units of thrombin into the vaginal cavity after aspiration of fluids, and in 5 of the 7 patients (71%) administered 240 mg of fibrinogen and 7.5 units of thrombin. Therefore, fibrin adhesive may be useful in the treatment of scrotal hydrocele.

Aged↗
PubMed1996

[Transesophageal echocardiography as a early postoperative monitoring patients after cardiovascular surgery: analysis of 500 consecutive studies].

In cardiac surgery significant residual lesions increase postoperative morbidity and mortality. To evaluate the usefulness of transesophageal echocardiography (TEE) as a early postoperative monitor in patients immediately after cardiovascular surgery, 500 consecutive patients were studied from April 1990 to December 1994. TEE was performed at the bedside in the intensive-care unit in all of these patients. TEE detected findings unsuspected by other perioperative tests or clinical examination in 103 (20.6%) of 500 patients. Imaging revealed unsatisfactory operative results that necessitated further surgery in 18 (3.6%) of the 500 patients. These data indicate that early postoperative TEE is useful in assessing immediate operative results and identifying patients with unsatisfactory results who are at increased risk for postoperative complications.

Cardiac Surgical Procedures↗
PubMed1996

[The prognostic factors in astrocytic tumors: analysis by the Kaplan-Meier method and the Weibull log-linear model].

As the prognosis of astrocytic tumors depends on various factors, identifying prognostic factors should be useful for developing strategies to cope with them. Between 1975 and 1994, more than 200 patients with astrocytic tumors were treated in Kagoshima University. Of these patients, 149 (grade I: 17, grade II: 42, grade III: 41, grade IV: 42, unproven: 7) have been followed up. Records of these patients were retrospectively reviewed for age at the time of initial symptoms, gender, histological grade (WHO), extent of tumor resection, radiation therapy, and administration of anticancer agents. We used the Kaplan-Meier method and the Weibull log-linear model to analyze the relation between survival time and these prognostic factors. Survival time was counted from onset of symptoms, and age of initial treatment was used as a covariant. The mean age of males at the initial diagnosis was 40.8 years (n = 77), and that of females was 39 years (n = 72). Using the Kaplan-Meier method, the mean survival time of the 149 patients was 101 months (males; 72.7 months, females; 134.5 months). Mean survival time of grade II was 144.3 months, that of grade III was 95.2 months, and grade IV (glioblastoma) was 15.9 months. Histological grades and mean ages of the groups showed a positive correlation. Among grades II, III and IV, the Kaplan-Meier survival curves were significantly different (p < 0.0001) according to the log-rank test. By the extent of surgical resection (subtotal or greater resection, partial resection, and less than partial resection), the mean survival time showed a significant difference (p < 0.05) on the log-rank test. However, we could not detect a significant difference in survival time between the group that received chemotherapy and the group which did not. The Weibull log-linear analysis indicated that gender, age, histological grade (WHO), extent of surgery, and dose of radiation therapy were prognostic factors. Covariants of grades II, III, and IV made survival time 0.314, 0.179, and 0.069 times as long as that of grade I. The survival time after "partial resection" became 1.415 times as long as the survival time after "less than partial resection". The covariant of "greater than subtotal resection" showed a prolonged survival time of 2.916 compared with that of "less than partial resection". As for age at treatment, the older the patient was, the shorter the survival time. The rate was 0.986 for each year of age. Irradiation of one Gy increased survival time by 1.015 times. Chemoimmunotherapy (dose of ACNU and interferon beta) could not be confirmed as an effective covariant.

Adult↗
PubMed1996

[A case report of active aortic prosthetic valve endocarditis due to methicillin-resistant Staphylococcus epidermidis].

A 71-year-old woman with active aortic prosthetic endocarditis due to Methicillin-resistant Staphylococcus epidermidis (MRSE) and subannular mycotic aneurysm and paravalvular leakage and acute mitral regurgitation underwent emergent surgical treatment. The mycotic aneurysm was closed using a prosthetic patch after surgical debridement. Re-aortic valve replacement with a 21-mm Hancock II prosthesis was performed at the paraannular position by utilizing the patch. Mitral valve was also replaced with a 27-mm Hancock II prosthesis. Antibiotic therapy was provided by vancomycin combined with rifampicin and gentamicin. The following regimen was given, vancomycin 1 g i.v. q12h for 6 weeks plus gentamicin 80 mg/day i.v. for 4 weeks plus rifampicin 450 mg/day orally for 6 weeks. Vancomycin and gentamicin doses were modified appropriately according to the monitored serum levels in the patient with renal failure. Postoperative course was uneventful. The patient is doing well 11 months after surgery and no recurrence of infection has been seen. We conclude that prompt surgical removal of the infected sources and appropriate antibiotic therapy based on the bacteriology may be the only curative treatment for uncontrolled infection at the active phase of MRSE prosthetic endocarditis.

Aged↗
PubMed1996

[Third mitral valve replacement--review of clinical aspects and surgical management in 10 cases].

Third mitral valve replacement (3rd MVR) have become more frequent as use of replacement procedures has become more widespread. However, little information exists to clearly document the determinants of 3rd MVR. To evaluate backgrounds and risks and complications of 3rd MVR, we reviewed data on 10 patients (6 male and 4 female, age averaged 58 +/- 8 years) who underwent 3rd MVR because of prosthetic valve malfunction during December 1986-May 1995. This represented 7.1% of total number of reoperations for valve surgery (10/140) during that period. The incremental effect of the 3rd MVR on hospital mortality and mobidity was studied by comparing first mitral valve replacement (1st MVR) and second mitral valve replacement (2nd MVR) and 3rd MVR. After an interval of 134 +/- 23 months, 3rd MVR was undertaken for congestive heart failure due to primary tissue failure in 65%, paravalvular leakage in 20%, prosthetic valve endocarditis in 15%. One patient died at 11 days postoperatively, for a mortality rate of 10%. Cause of death was related to multiple organ failure due to low cardiac output syndrome. The surgical risk of 2nd MVR and 3rd MVR is higher than that of 1st MVR, but there is no conclusive evidence that the difference between 2nd MVR and 3rd MVR is statistically significant. With improvement intraoperative strategies, the operative risk in patients undergoing 3rd MVR has been markedly reduced.

Bioprosthesis↗
PubMed1996

[A case of CEA and CA19-9 producing recurrent transitional cell carcinoma in an Indiana pouch after total cystectomy].

A 73-year-old female with transitional cell carcinoma (TCC) of the bladder underwent total cystectomy and Indiana pouch replacement in April, 1992. Histological examination revealed grade 3 TCC. In February 1995, she complained of gross hematuria. Intravenous pyelography (IVP) revealed a right non-functional kidney and filling defect in the Indiana pouch. We suspected colon cancer in the Indiana pouch because the levels of serum carcino-embryonic antigen (CEA) and CA19-9 were elevated. Endoscopic biopsy of intrapouch tumor was done. Pathological examination revealed grade 2 TCC. In July 1995, right nephroureterectomy with resection of Indiana pouch was performed and the surgical specimen revealed renal pelvic and ureteral cancer, grade 2 TCC. The levels of serum CEA and CA19-9 returned to the normal range 21 days after the operation. CEA and CA19-9 histochemical stain of renal pelvic and ureteral cancer were positive. Also CEA-, CA19-9-positive cells were detected in the specimens of the bladder tumor from the total cystectomy performed in 1992. This rare case is discussed and the literature is reviewed.

Aged↗