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Biomedical subjects

Seiji Ishikawa

Publications and source records attributed to Seiji Ishikawa.

17 recordsLinked to original sources
PubMed2006

Micelle formation of bile salts and zwitterionic derivative as studied by two-dimensional NMR spectroscopy.

The self-association of sodium taurodeoxycholate (NaTDC) and a zwitterionic derivative of cholic acid (CHAPS) in deuterium oxide was investigated by one- and two-dimensional nuclear magnetic resonance spectroscopy (NMR) spectroscopy. Analysis of the concentration dependence of the chemical shifts of several protons suggested that NaTDC and CHAPS form nonamers and heptamers, respectively, as well as dimer. The equilibrium constants of dimerization and the micellar aggregation numbers are close to the literature values. From the intensities of intermolecular cross-peaks in the nuclear Overhauser effect spectroscopy (NOESY) and rotating frame nuclear Overhauser effect spectroscopy (ROESY) spectra of NaTDC and CHAPS micellar solutions, partial structures of their micelles were estimated. The CHAPS micelle consists mainly of the back-to-back association, similarly to taurocholate (NaTC). However, the NaTDC micelle consists of the back-to-face association, because the face of NaTDC is rather hydrophobic. Furthermore, the back of bile molecules forms a convex plane and the face forms a concave plane. The back-to-face structure of NaTDC will be stabilized by a close contact between these planes. The chemical shift changes of several protons of CHAPS and NaTC in the micellar state are close to each other, but are different from those of NaTDC. This finding is consistent with the difference in their micellar structures.

Bile Acids and Salts↗
PubMed2006

Subcutaneous emphysema and pneumomediastinum after translaryngeal intubation: tracheal perforation due to unsuccessful fiberoptic tracheal intubation.

A 77-year-old man was scheduled to undergo a cervical lymph node biopsy under general anesthesia. Although awake, nasotracheal fiberoptic intubation was initially planned because of an anticipated difficult airway, the attempt was unsuccessful. Orotracheal intubation was subsequently performed under direct laryngoscopy without difficulty. After initiating positive pressure mechanical ventilation, subcutaneous and mediastinal emphysema developed. The cause of this emphysema was considered to be tracheal perforation after an unsuccessful attempt at fiberoptic tracheal intubation.

Aged↗
PubMed2006

The evolution of cerebral ischemia in a rat model of complete unilateral carotid artery occlusion with severe hypotension as detected by diffusion-, T2-, and postcontrast T1-weighted magnetic resonance images.

Severe internal carotid artery stenosis or occlusion is considered to be one of the important causes of stroke. The authors created a complete unilateral carotid artery occlusion model in 15 Sprague-Dawley rats, induced severe hypotension for at least 36 minutes by exsanguination with the target mean arterial pressure being equal or less than 35 mmHg, and investigated the temporal and spatial evolution of cerebral ischemia by diffusion-, T2-, and postcontrast T1-weighted magnetic resonance images. Cerebral ischemia was detected in most regions of the right middle cerebral artery territory during exsanguination. There was no significant relationship between ischemic lesion volume detected on apparent diffusion coefficient (ADC) map (ADC lesion volume) and infarction volume found on histopathology. However, there was a linear relationship between the change in ADC lesion volume at blood reinfusion (after reinfusion minus before reinfusion) and the enlargement of the lesion volume during the postreinfusion period (Y = 0.4X + 161.7, P = 0.0066) and a significant logarithmic correlation between the volume of vasogenic edema found on postcontrast T1-weighted image at 1 hour of the postreinfusion period and the enlargement of the lesion volume during the postreinfusion period (Y = 62.1 x logX - 115.4, P = 0.022). In conclusion, although it may be difficult to predict the outcome of cerebral ischemia (infarction volume) from the lesion volume during exsanguination, the evolution of cerebral ischemia may be partly predicted by lesion volume changes seen on the ADC maps at the time of the blood reinfusion or by the severity of blood-brain barrier disruption at the early stage of the postreinfusion period.

Animals↗
PubMed2006

Molecular motions of alpha-cyclodextrin on a dodecyl chain studied by molecular dynamics simulations.

Motions of an alpha-cyclodextrin (alpha-CD) molecule on a dodecyl chain adopting the all-trans conformation were investigated in the presence of water by molecular dynamics simulations with CVFF force fields, where the trimethylammonium group of dodecyltrimethylammonium bromide (DTAB) is protruded outside the secondary hydroxyl rim of alpha-CD (the secondary-in structure). The alpha-CD molecule shuttled rapidly on the chain without decomplexation. This rapid motion is consistent with the NMR data. The plane formed by 6 O4 atoms of alpha-CD is most populated between the C6 and C7 atoms of DTAB. This structure is very close to that estimated by NMR. The alpha-CD molecule underwent a restricted rotation in a range of 60 degrees with regard to the plane of the dodecyl chain: this plane at the most population is middle between the two diagonal lines of the normal hexagon formed by 6 O4 atoms of alpha-CD. The published NMR data were reanalyzed in terms of the rotation angle, and a slightly better structure was obtained. The distortion of the alpha-CD cavity from the normal hexagon was decreased upon complex formation with DTAB. The deviation of the center of alpha-CD from the center of the dodecyl chain predicted by molecular dynamics simulations is consistent with the NMR data. The secondary-in structure is energetically more stable than the primary-in structure, as calculated by molecular mechanics with CVFF and Amber force fields. This result is consistent with the NMR data. Molecular dynamics simulations were also carried out for the primary-in structure. Some of the results are close to those of the secondary-in structure.

Computer Simulation↗
PubMed2006

[Remifentanil].

Remifentanil is a potent mu-opioid receptor agonist and has some unique pharmacokinetic characteristics compared to other anilidopiperidine opioids (e.g. fentanyl, alfentanil, and sufentanil). As remifentanil is metabolised rapidly by nonspecific esterases that are widespread throughout the plasma and tissuses, its duration of action is very short. It is cleared very rapidly, and its clearance is not affected by renal and hepatic function. The context-sensitive half-time of remifentanil remains consistently short, even after administration for a long time. Consequently, emergence is quick even after anesthesia of long duration. As other piperidine opioids, remifentnil has some adverse effects such as respiratory depression, muscle rigidity, bradycardia, and nausea as well as vomiting. Because of the rapid dissipation of analgesic effect following remifentanil discontinuation, postoperative analgesia should be provided before or soon after anesthesia using longer-acting opioid analgesics, non-opioid analgesics, or local as well as regional anesthesia.

Analgesics, Opioid↗
PubMed2005

Second primary cancers in patients with stage III non-small cell lung cancer successfully treated with chemo-radiotherapy.

BACKGROUND: Patients successfully treated for non-small cell lung cancer (NSCLC) remain at risk for developing second primary cancer (SPC). The purpose of the current study is to assess the incidence of SPC and the impact of smoking status on the SPC in long-term survivors with stage III NSCLC after chemo-radiotherapy. METHODS: Using the database from the Japan National Hospital Lung Cancer Study Group between 1985 and 1995, information was obtained on 62 patients who were more than 3 years disease-free survivors. Details of clinical information and most smoking history were available from the questionnaire. RESULTS: Nine of the 62 patients developed SPC 3.9-12.2 years (median, 6.2 years) after the initiation of the treatment. The site of SPC was 2 lung, 1 esophagus, 2 stomach, 1 colon, 1 breast, 1 skin and 1 leukemia. Among these nine, three cancers occurred inside the radiation field. The relative risk of any SPC was 2.8 [95% confidence interval (CI) 1.3-5.3]. The risk changed with the passage of time and it increased significantly (5.2 times at or beyond 7 years) after the treatment. In univariate analysis, the patients who were male, had more cumulative smoking and continued smoking, had an increased risk of SPC [relative risk (RR) 2.7, CI 1.1-5.3; RR 3.0, CI 1.2-6.2; RR 5.2, CI 1.6-11.7, respectively]. In multivariate analysis, factors including smoking status and histological type had no effect on the development of a SPC. CONCLUSION: The patients with stage III NSCLC successfully treated with chemo-radiotherapy were at risk for developing SPC and this risk increased with time.

Adult↗
PubMed2005

Delayed emergence from anesthesia resulting from cerebellar hemorrhage during cervical spine surgery.

Cerebellar hemorrhage is an unpredictable complication of spinal surgery. We encountered a case of cerebellar hemorrhage presenting with delayed emergence from anesthesia and hemiplegia after resection of an intradural extramedullar tumor from the cervical spine. Postoperative brain computed tomography revealed hematoma in the cerebellar vermis and right cerebellar hemisphere. The patient made a gradual recovery with conservative treatment. Although the mechanism of cerebellar hemorrhage remains speculative, loss of cerebrospinal fluid may play an important role. Cerebellar hemorrhage must therefore be considered in patients with unexplained neurological deterioration or disturbance on emergence from anesthesia after spinal surgery.

Aged↗
PubMed2005

[Anesthetic management of an infant with asplenia and single atrium single ventricle undergoing ear tube surgery for otitis media: a case report].

A 13-month-old girl with cyanotic congenital heart disease; single atrium, single ventricle, common atrioventricular (AV) valve, pulmonary atresia and total anomalous pulmonary venous drainage, suspected of asplenia underwent ear tube surgery for otitis media. She had undergone bilateral Blalock-Taussig shunts for her heart disease. She had congestive heart failure due to moderate to severe common AV valve regurgitation and often experienced respiratory tract infection with sputum. Oxyhemoglobin saturation measured by pulse oximetry was 75-80% and polycythemia was found in complete blood count. We chose tracheal intubation for her airway management because of a large amount of sputum. General anesthesia was maintained with sevoflurane, nitrous oxide and oxygen for ear tube surgery. During anesthesia she showed several episodes of desaturation which were well managed by frequent tracheal suctioning. Her circulation was stable with 50% N2O and sevoflurane 1.7-2.0%. The operation was performed uneventfully and the patient was discharged to the ward after tracheal extubation. Asplenia is frequently complicated with cyanotic congenital heart disease and increased susceptibility to bacterial infection. Anesthesia for these patients with upper respiratory infection should be managed with tracheal intubation even for a short surgery.

Abnormalities, Multiple↗
PubMed2005

[Anesthetic management of a patient with paroxysmal nocturnal hemoglobinuria and suspected abdominal venous thrombosis].

A 59-year-old man with paroxysmal nocturnal hemoglobinuria (PNH) underwent an operation for lumbar disk herniation. He was given warfarin, aspirin, and steroid for PNH and suspected venous thrombosis. PNH is a hemolytic anemia due to an acquired red blood cell membrane defect at the stem cell level. The patient with PNH has a risk of massive hemolysis induced by stresses such as acidosis, fever, operation, trauma and overfatigue. Other main symptoms of PNH are venous thrombosis and deficient hematopoiesis. We prevented massive hemolysis by increasing the dose of steroid and avoiding acidosis, fever and dehydration during the perioperative period. Warfarin and aspirin were changed to dalteparin before operation for the prevention of venous thrombosis as well as for easy control of bleeding tendency. The perioperative course was uneventful without obvious hemolysis, venous thrombosis and unnecessary bleeding.

Anesthesia, General↗
PubMed2005

[A case of stagnation of a large amount of irrigation fluid in abdominal cavity during hysteroscopic myomectomy].

A 30-year-old woman was scheduled to undergo hysteroscopic myomectomy for uterine myoma. Spinal anesthesia was performed with 3 ml of 0.5% bupivacaine and she was sedated with intravenous propofol during the surgery. After the surgical procedure, propofol infusion was stopped. The patient soon awoke and vomited frequently and repeatedly. Her serum sodium concentration was as low as 129 mEq x l(-1) and fluid overload (water intoxication) was suspected. Because the abdominal X-P revealed that two parts of the surgical instrument remained in her uterine cavity at that time, hysteroscopic procedure was restarted. General anesthesia was induced with propofol and maintained with nitrous oxide and sevoflurane. During the procedure, uterus was accidentally perforated and one of the parts moved into the abdominal cavity. When the laparotomy started to fix uterine perforation, the abdomen of the patient became remarkably distended. During the laparotomy, it was revealed that 4800 ml of irrigation fluid had been accumulated in the abdominal cavity. Although hysteroscopic surgery is generally considered non-invasive, two major complications (fluid overload and uterine perforation) occurred in this case. This case suggests that anesthetists must remain alert for the signs of these complications during hysteroscopic surgery.

Abdominal Cavity↗
PubMed2004

Structure and ethanol complexation of cyclic tetrasaccharide in aqueous solution studied by NMR and molecular mechanics.

The structure and ethanol complexation of a cyclic tetrasaccharide (CTS) in aqueous solution were investigated by proton NMR spectroscopy and molecular mechanics calculations. Two glucose units, A and B, of CTS are alternatively bonded by alpha-1,3 and alpha-1,6 linkages. The overlapped signals of protons A5, A6S, A6R, B3, B6S and B6R were resolved by spectral simulations to determine their chemical shifts and vicinal coupling constants. All vicinal coupling constants except for the A5-A6 spin system are consistent with the dihedral angles in the X-ray crystal structure. Each of protons A5, A6S, and A6R in the two units of A is equivalent with respect to the chemical shift. The vicinal coupling constants of (3)J(5-6S) and (3)J(5-6R) for unit A are close to the average of two rotamers that are present in crystals. The intensities of cross-peaks in the rotating frame nuclear Overhauser effect spectroscopy (ROESY) spectrum were rather well correlated with the effective distances calculated for the X-ray structure and molecular mechanics structures calculated in vacuo and water, although they are slightly better correlated with molecular mechanics structure in vacuo than with the other structures. From the changes of the chemical shifts of several CTS protons with increasing ethanol concentration, it was suggested that adsorption sites of ethanol on the plate structure of CTS are protons B2 and B4 (site B) in the concave face side and protons A1 and A2 (site A) in the convex back side. The binding constants for sites A and B are 0.0061 and 0.0176 M(-1), respectively. These binding constants are much smaller than a value of 4.1 M(-1) for the ethanol-alpha-cyclodextrin complex.

Binding Sites↗
PubMed2003

A case of difficult airway due to lingual tonsillar hypertrophy in a patient with Down's syndrome.

In this report, we describe airway management of symptomatic lingual tonsillar hypertrophy in a pediatric patient with Down's syndrome. Besides obstructive sleep apnea, the history included a small atrial septal defect with mild aortic regurgitation and Moyamoya disease. Anesthesia was induced with IV administration of 1 mg/kg of propofol, followed by inhalation of sevoflurane in 100% oxygen. Muscle relaxants were not used on induction. Rigid laryngoscopy could not visualize the epiglottis because of hypertrophied tonsillar tissue, and mask ventilation became difficult when spontaneous breathing stopped. We avoided using a laryngeal mask airway because of a slight bleeding tendency presumably caused by preoperative antiplatelet therapy. Fiberoptic bronchoscopy through the nasal cavity in combination with jet ventilation successfully identified the glottis and allowed nasotracheal intubation to be accomplished. After lingual tonsillectomy, the patient was extubated on the seventh postoperative day, after supraglottic edema had resolved. Fiberoptic nasotracheal intubation under inhaled anesthesia may therefore be preferable in pediatric or uncooperative patients with symptomatic lingual tonsillar hypertrophy.

Anesthesia, General↗
PubMed2002

[Sequential changes of various parameters of arterial blood samples].

BACKGROUND: Since the values of various parameters in arterial blood samples changes with time, they should be measured without delay. There are some situations, however, where it is quite difficult to carry out the measurement immediately. In this study, we aim to obtain a series of parameters by which we can estimate true values from stale blood samples. METHODS: Arterial blood gases (PaCO2, PaO2, pH), electrolytes, blood sugar and lactate were measured at 0 min, 30 min, 60 min after collecting the samples. Cytometry was done at 0 min. We calculated proton ion concentration ([H+]) and oxygen content (CaO2). Relationships between the change of various parameters in arterial blood samples and the numbers of red blood cell (RBC), white blood cell (WBC) and platelet were analyzed using multiple regression analysis. RESULT: The values of PaCO2, lactate and [H+] increased, and those of PaO2, blood sugar and CaO2 decreased with time. Electrolytes changed little. There were significant relationships between the number of RBC and the change of blood sugar, and between the number of WBC and the change of CaO2 value. CONCLUSION: From these result, we found a series of expression by which we can estimate appropriate values from stale blood samples.

Anesthesia, General↗
PubMedDate not supplied

Solution structures of 1:1 complexes of oxyphenonium bromide with beta- and gamma-cyclodextrins.

The solution structures of complexes of oxyphenonium bromide (OB) with beta- and gamma-cyclodextrins (beta- and gamma-CDs, respectively) in deuterium oxide have been investigated by 500 MHz proton NMR spectroscopy and molecular mechanics calculations. The chemical shifts induced by complex formation provide the 1:1 binding constants and the chemical shift variations, DeltadeltaOB-CD, with complexation for the protons of OB and the CDs. The observed binding constants are very close to those obtained by other methods and are in the following order: beta-CD > gamma-CD > alpha-CD. Initial structures of the complexes are constructed on the basis of the ROESY spectra and the DeltadeltaOB-CD values and are optimized by molecular mechanics calculations. The intermolecular distances between the protons of OB and CD calculated for these structures are well-correlated with the observed ROESY intensities. The cyclohexyl group of OB penetrates deeply into a beta-CD cavity, and the phenyl group is close to the wide rim of the cavity. The phenyl and cyclohexyl groups of OB are both incorporated into a gamma-CD cavity. Furthermore, these structures of the complexes are consistent with the suppression of bitter taste and basic hydrolysis of OB by CDs and the polarity of binding sites of OB.

Kinetics↗