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Biomedical subjects

S Kitamura

Publications and source records attributed to S Kitamura.

At least 559 records · Page 31Linked to original sources
PubMed1993

[Changes in regional cerebral blood flow during auditory cognitive tasks--a PET activation study with odd-ball paradigm].

In order to investigate the relation between auditory cognitive function and regional brain activation, we measured the changes in the regional cerebral blood flow (CBF) using positron emission tomography (PET) during the "odd-ball" paradigm in ten normal healthy volunteers. The subject underwent 3 tasks, twice for each, while the evoked potential was recorded. In these tasks, the auditory stimulus was a series of pure tones delivered every 1.5 sec binaurally at 75 dB from the earphones. Task A: the stimulus was a series of tones with 1000 Hz only, and the subject was instructed to only hear. Task B: the stimulus was a series of tones with 1000 Hz only, and the subject was instructed to push the button on detecting a tone. Task C: the stimulus was a series of pure tones delivered every 1.5 sec binaurally at 75 dB with a frequency of 1000 Hz (non-target) in 80% and 2000 Hz (target) in 20% at random, and the subject was instructed to push the button on detecting a target tone. The event related potential (P300) was observed in task C (Pz: 334.3 +/- 19.6 msec). At each task, the CBF was measured using PET with i.v. injection of 1.5 GBq of O-15 water. The changes in CBF associated with auditory cognition was evaluated by the difference between the CBF images in task C and task B. Localized increase was observed in the anterior cingulate cortex (in all subjects), the bilateral associate auditory cortex, the prefrontal cortex and the parietal cortex. The latter three areas had a large individual variation in the location of foci.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[Clinical study of fluconazole for systemic fungal infections with hematological disorders].

Fluconazole (FLCZ) was administered orally or intravenously to 161 patients with systemic fungal infections complicated with hematological disorders and it was possible to evaluate clinical efficacies in 109 patients. Systemic fungal infections were documented in 48 patients and suspected in 61 patients. The overall clinical efficiency rates were 43.8% (21/48) in patients with documented fungal infections, and 55.7% (34/61) in patients with suspected fungal infections. Therefore, the overall clinical efficacy rate was 50.5% (55/109). Side effects were observed in 5 patients with an incident rate of 3.1% (5/161), but there was none of them was serious. These results indicate that FLCZ is an agent with good potential in treatment of systemic fungal infections in patients with hematological disorders.

Adolescent↗
PubMed1993

[Aortic valve replacement and coronary artery bypass grafting in a patient with a porcelain aorta due to aortitis syndrome].

Clamping a calcified aorta during cardiac operation increases the risk of cerebral embolism by aortic debris. We operated upon a 61-year-old female with severe angina pectoris due to aortic regurgitation and bilateral coronary calcific ostial stenosis associated with porcelain aorta secondary to aortitis syndrome. At operation, cardiopulmonary bypass was begun with profound hypothermia. Using an occlusion balloon catheter inflated in the ascending aorta, the calcified aorta was incised with scissors. However accidentally the balloon was ruptured by intimal calcification of the ascending aorta, and cardiopulmonary bypass was discontinued for 11 minutes under 20 degrees C hypothermia. Extensive removal of the intimal calcification of the ascending aorta was performed with care and then, the aorta was clamped. Aortic valve replacement and triple coronary bypass operation (SVG to LAD, SVG to LCX, GEA to RCA) were performed. The proximal anastomoses of the SVGs were made on the decalcified aortic wall. The postoperative course was uneventful and aortography revealed neither dissection nor dilatation of the ascending aorta following extensive decalcification procedure of the ascending aorta, and the 3 grafts were all patent. From the experience, we learned that extensive removal of calcification of the aorta can be successfully performed in porcelain aorta due to aortitis syndrome. For CABG in aortitis syndrome, the use of ITA is rarely possible, but the GEA may be a versatile graft.

Aorta↗
PubMed1993

[Cell viability assessment of cold-preserved (4 degrees C) and cryopreserved (-196 degrees C) allograft valves by flowcytometric analysis].

We introduced cryopreservation technique to store the allograft valve and subsequently commenced the use of the cryopreserved aortic allograft valve for aortic valve replacement. For the clinical use of the allograft valve, it is essential to evaluate the cell viability. We assessed cell viability of the allograft valve by flowcytometry (FCM), using a fluorescein diacetate (FDA)-propidium iodide (PI) stain. Pulmonary allograft valves were harvested from the cadavers with a consent. Of the 9 valves collected and sterilized in 4 degrees C antibiotic solution for 48 hours, 4 valves were stored under refrigeration (cold-preserved), and the remaining 5 valves were cryopreserved. The warm ischemic time from cardiac death to valve preservation was 7.3 +/- 5.4 hours. The cold-preserved valves were stored at 4 degrees C in the nutrient medium (TC-199, calf serum and HEPES buffer). The cryopreserved valves were frozen by a programmable freezer to -80 degrees C in the same nutrient medium containing 10% dimethylsulfoxide (DMSO), and subsequently stored in liquid nitrogen (-196 degrees C). We assessed the cell viability of the allograft valve leaflet, before storage and at 2 weeks, 1 month and 2 months after the storage. Suspensions of the valve leaflet fibroblasts were double-stained with FDA (1 micrograms/ml) and PI (1 microgram/ml) for flowcytometric analysis of the viable cells (cells showing a chromatic response to FDA but no response to PI). In the cold-preserved group, percentage of the viable cell was 90.3 +/- 3.6% before storage, 62.0 +/- 3.0% after 1 month of storage, and 50.3 +/- 3.7% after 2 months of storage.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗
PubMed1993

[Flow cytometric analysis of the DNA content in resected thymomas].

Nuclear DNA contents were determined by flow cytometry in 31 resected thymomas. Ten (32%) of the 31 thymomas showed DNA aneuploid, and the presence of aneuploidy was well correlated with advanced clinical stage. Patients with an aneuploid tumor had a poor prognosis than those with a diploid tumor, demonstrating a survival rate of 50% at 7 years in aneuploidy compared to 100% at the same period in diploid patients (p < 0.05). In addition, patients with a high DNA index (DI > or = 1.5) tended to have a poor prognosis than those with a low DI. The analysis of DNA content can be an important prognostic index in patients with a thymoma.

Adult↗
PubMed1993

Successful repair and postoperative management of tetralogy of Fallot in a patient with maple syrup urine disease.

A case of tetralogy of Fallot with maple syrup urine disease (MSUD) treated surgically is reported. This 2-year-old female patient developed neurologic deterioration after intracardiac repair. Postoperative management, which included peritoneal dialysis, intravenous hyperalimentation, and early intestinal alimentation with branched-chain amino acid-free milk was successful. At the present time, two years after the operation, she is doing quite well with a special diet for MSUD. This is the first report on a patient with MSUD who underwent open heart surgery using a cardiopulmonary bypass, stressing the importance of postoperative management.

Cardiopulmonary Bypass↗
PubMed1993

[Simultaneous operation of Cabrol's operation and sternal turnover with rectus abdominal flap].

We performed simultaneous operation of sternal turnover and Cabrol operation for a 28-year-old man, who had 3rd grade funnel chest and annuloaortic ectasia with 3rd grade aortic regurgitation. We think when both annuloaortic ectasia and funnel chest are indicated for operation, simultaneous operation is to be considered and the combination of Cabrol operation and sternal turnover with rectus abdominal flap is the best procedure.

Adult↗
PubMed1993

[Successful surgical management for chronic sternal osteomyelitis and anterior mediastinal abscess after double valve replacement by total sternectomy and pectoralis major muscle flaps].

A 63-year-old woman underwent double (aortic and mitral) valve replacement in February, 1987. Thirty days later, purulent drainage developed at the sternotomy incision with high fever. Wound cultures revealed staphylococcus aureus. She was treated by local wound care with antibiotics. About one month later, she had a satisfactory wound healing. But three cutaneous fistulas with discharge emerged at the sternotomy incision in November (9 months later) and the cultures grew the same species. The fistulogram showed the communication between these tracts and the mediastinum. The diagnosis of chronic sternal osteomyelitis and anterior mediastinal abscess was made. At first the resection of the xiphoid process and the mediastinal drainage were carried out in March, 1988. Inspite of this procedure, she still had persistent purulent discharge. Then, en bloc excision of the infected sternum and the adjacent costal cartilage were performed in April. The defect was obliterated with the bilateral pectoralis major muscle flaps. After the radical operation, her wound was completely healed, even though the ventilatory support was needed for 24 days because of flail chest due to the anterior chest wall instability. Now she has been free from recurrence for four years. Total sternectomy and pectoralis major muscle plombage seem to be a very effective management in chronic sternal osteomyelitis.

Abscess↗
PubMed1993

[The effect of LDL-apheresis on the long-term prognosis of hypercholesterolemic patients with coronary artery bypass grafts: a multicenter study].

Hypercholesterolemia is well known as a risk factor which had been shown to affect the long-term prognosis after coronary artery bypass grafting (CABG). The data were collected from multi-institutions documenting the long-term results of CABG in 61 hypercholesterolemic patients who received LDL-apheresis. Mean post-CABG period was 50 +/- 34 (+/- SD) months. Mean period of therapy by LDL-apheresis using Liposorber system after CABG was 25 +/- 17 months with a frequency of once per 2.6 +/- 1.3 weeks. Before initiating LDL-apheresis mean serum cholesterol (TC) and LDL-cholesterol (LDL-C) were 327 mg/dl and 261 mg/dl, respectively. With combined LDL-apheresis and lipid-lowering drug therapy mean TC and LDL-C were reduced to 247 mg/dl and 177 mg/dl immediately pre-apheresis and 106 mg/dl and 60 mg/dl immediately post-apheresis, respectively. Two of 61 patients had PTCA post CABG. Percent free from cardiac event during the long-term period post CABG as calculated by the life-table method was 97% at 3 years and 94% at 4 years and thereafter. While number of the patients is still small, the aggressive cholesterol-lowering therapy by LDL-apheresis is suggested to improve the prognosis of hypercholesterolemic patients with bypass grafts.

Adult↗
PubMed1993

[Late results of aortic valve plasty (aortic leaflet slicing) simultaneously performed with mitral valve surgery].

We followed the course of 20 patients who underwent aortic valve plasty (AVP) combined with mitral valve surgery for rheumatic mild aortic valve disease in association with severe mitral valve disease. At operation, all patients underwent aortic leaflet slicing with a knife, and aortic commissurotomy were performed additionally in 10 patients. After surgery, the degree of aortic valve regurgitation and the amplitude of aortic leaflet motion were assessed chronologically, using ultrasound cardiography. One month after surgery, all but one patients showed a reduction in regurgitation to degree I or less. From the third post-operative year, however aortic valve regurgitation tended to increase again. However, the post-operative degree of regurgitation was observed not to be severer than the pre-operative degree of regurgitation, and no patients showed aggravation of aortic valve regurgitation attributable to exacerbation of mitral valve disease. We divided the patients into two groups according to improvement of aortic valve regurgitation. In the group where the degree of regurgitation returned to the pre-operative one, the degree of amplitude of leaflet motion began to reduce from the third post-operative year and was nearly equal to the pre-operative one at the fifth post-operative year. The results of this study can be summarized as follows: 1. From the third post-operative year, aortic regurgitation was aggravated and aortic valve motion amplitude decreased. 2. The number of sliced valve leaflets and incised commissures did not correlate well with the post-operative reduction in regurgitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

[A successful operation of isolated levocardia with left atrial isomerism, polysplenia and tetralogy of Fallot].

A four-year-old boy who had isolated levocardia associated with left atrial isomerism, polysplenia and tetralogy of Fallot underwent successful corrective surgery. In addition, these anomalies were complicated by interrupted inferior vena cava, azygos continuation, and total anomalous hepatic venous connection. Because of these systemic venous anomalies, cardiopulmonary bypass presented us some problems of venous cannulations. We used 4 direct venous cannulations; i.e., superior vena cava, persistent left superior vena cava through coronary sinus, azygos vein and hepatic vein. Reports of total correction in patients with isolated levocardia associated with tetralogy of Fallot are rare, and we report the case with some reviews of the related literature.

Abnormalities, Multiple↗
PubMed1992

Crystal structure of methyl 3-O-beta-D-glucopyranosyl-beta-D-glucopyranoside (methyl beta-D-laminarabioside) monohydrate.

Crystals of methyl 3-O-beta-D-glucopyranosyl-beta-D-glucopyranoside (methyl beta-D-laminarabioside) belong to the orthorhombic system, space group P2(1)2(1)2, with a = 14.548(2), b = 24.252(7), c = 4.938(1) A, and Z = 4. The crystal structure was solved by the direct method and refined by the full-matrix least-squares procedure to an R-value of 0.062 for 1099 observed reflections in the X-ray data. The molecular structure is similar to that of beta-D-laminarabiose. The torsional angles around the glycosidic bonds are influenced by both the existence of an intramolecular hydrogen bond at O-4'... O-5 and the exo-anomeric effect. In the nonreducing residue, the exocyclic O-5-C-5-C-6-O-6 and C-4-C-5-C-6-O-6 torsional angles are (+)gauche and trans, respectively, whereas the corresponding torsional angles in the reducing residue are (-)gauche and (+)gauche. One water molecule cocrystallizes with each disaccharide, and the crystal structure is stabilized mainly by intra- and inter-molecular hydrogen bonds involving water molecules.

Carbohydrate Conformation↗
PubMed1992

New bronchodilators. 3. Imidazo[4,5-c][1,8]naphthyridin-4(5H)-ones.

In order to develop new oral bronchodilators, a series of novel imidazol[4,5-c][1,8]naphthyridin-4(5H)-ones 5 were designed and synthesized. Some of these new heterocycles exhibited more potent bronchodilator activity in vitro and in vivo than theophylline. With respect to modification at the 5-position, both phenyl and n-butyl substitution produced potent activity. Though bulk tolerance at N-3 is observed with short and small lipophilic groups, any substitution at the other positions and transformations of the parent skeleton eliminated activity. Thus 5-phenyl-1H-imidazo[4,5-c][1,8]naphthyridin-4(5H)-one (23) (KF17625), which satisfied these conditions, was selected for further studies (antigen inhalation-induced bronchospasm model; minimum effective dose (MED) = 1 mg/kg, po; antigen-induced contraction of trachea (the Schultz-Dale reaction), IC50 = 2.2 microM). Compound 23 inhibited carbachol-, histamine-, or leukotriene D4-induced contraction and relaxed spontaneous tone in guinea pig isolated tracheal preparations with, 4- to 16-fold greater potency than aminophylline. Thus it appeared to relax directly the airway smooth muscle. 23 did not have any influence on adenosine binding at 10 microM, but inhibited canine tracheal phosphodiesterase (PDE) IV (IC50 = 12 microM) and concanavalin-A-induced histamine release from rat mast cells (44% inhibition at 10 microM). Although the detailed mechanisms of these compounds remain to be elucidated, this series of novel tricyclic heterocycles represents a new class of bronchodilator.

Animals↗
PubMed1992

Contribution of the central interaction between calcium and sodium to hemodynamic regulation in spontaneously hypertensive rats.

The contribution of the central interaction between calcium and sodium to hemodynamic regulation was assessed in spontaneously hypertensive rats (SHRs) and Wistar-Kyoto (WKY) rats. The effect of a high calcium solution (Ca2+, 130 mg/dl, 10 microliters) infused into the cerebral ventricle (i.c.v.) on hemodynamic responses induced by a high sodium solution (Na+, 1,000 mEq/1, 10 microliters) i.c.v. and the mechanism by which high Ca2+ affects the hemodynamic responses induced by high Na+ i.c.v. were studied. High Na+ i.c.v. induced a pressor response with tachycardia in the SHRs, but induced a pressor response with reflex bradycardia in the WKYs. Prior treatment with high Ca2+ i.c.v. attenuated the pressor response induced by high Na+ i.c.v. (+55.6 +/- 4.4 to +33.1 +/- 3.2 mmHg, P < 0.01) and restored reflex bradycardia (+86.4 +/- 7.7 to -26.7 +/- 7.6 bpm, P < 0.01) in SHRs. Whereas prior treatment with high Ca2+ i.c.v. attenuated the pressor response (+35.7 +/- 2.0 to +22.2 +/- 4.0 mmHg, P < 0.05), it did not alter the degree of reflex bradycardia (-81.7 +/- 7.1 to -69.2 +/- 120 bpm, n.s.) in WKYs. Ganglionic blockade attenuated the pressor response (+56.9 +/- 3.5 to +42.9 +/- 2.3 mmHg, P < 0.05) and restored reflex bradycardia (+82.1 +/- 10.3 to -65.9 +/- 11.0 bpm, P < 0.01) in SHRs, whereas, inhibition of arginine vasopressin attenuated the pressor response without modification of the tachycardic response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

New bronchodilators. 1. 1,5-Substituted 1H-imidazo[4,5-c]quinolin-4(5H)-ones.

A series of novel xanthine-based tricyclic heterocycles in 1H-imidazo[4,5-c]quinolin-4(5H)-ones was designed, synthesized, and tested as potential active bronchodilators. Inhibition of the Schulz-Dale (SD) reaction-induced contraction in trachea and inhibition of antigen inhalation-induced bronchospasm in passively sensitized guinea pigs served as primary in vitro and in vivo assays, respectively. Simultaneous measurement of acute lethal toxicity (minimum lethal dose; MLD, po) in mice allowed determination of a safety margin. The bronchodilatory activity of these heterocycles was considerably varied with the nature of substituents at the 5-position. The most active substituents at the 2- and 5-positions and on the aromatic ring were found to be hydrogen, n-butyl, and hydrogen, respectively. There was a bulk tolerance for lipophilic substituents at the 1-position. 5-Butyl-substituted compounds appeared to be less toxic than theophylline on the basis of MLD data. Thus 5-butyl-1-methyl-1H-imidazo[4,5-c]quinolin-4(5H)-one (10) (IC50 value of the SD assay = 0.25 microM, MLD > 300 mg/kg) was selected for further studies. Compound 10 (KF15570) reduced bronchoconstriction produced by antigen (Konzett-Rössler preparation in anesthetized guinea pigs, ED50 = 0.42 mg/kg, iv) more effectively than aminophylline (ethylenediamine salt of theophylline, ED50 = 7.8 mg/kg, iv) but had fewer side effects on the heart and CNS than theophylline. Compound 10 and its derivatives showed weak adenosine antagonism and phosphodiesterase (PDE) inhibition which could not account for their potent bronchodilation. Although their precise mechanism of action remains unclear, this series of novel tricyclic heterocycles represents a new class of bronchodilator.

Airway Resistance↗
PubMed1992

Differential scanning calorimetric study of the thermal unfolding of mutant forms of phage T4 lysozyme.

In two recent papers, we reported the effects of several point mutations on the thermodynamics of the thermal unfolding of the lysozyme of phage T4 as determined by differential scanning calorimetry. The mutants studied were R96H [Kitamura, S., & Sturtevant, J.M. (1989) Biochemistry 28, 3788-3792] and T157 replaced by A, E, I, L, N, R, and V [Connelly, P., Ghosaini, L., Hu, C.-Q., Kitamura, S., Tanaka, A., & Sturtevant, J.M. (1991) Biochemistry 30, 1887-1891]. Here we report the results of a similar study of the single mutations A82P, A93P, and G113A and the double mutation C54T:C97A. The three single mutants all show small apparent stabilization at pH 2.5 and 46.2 degrees C (the denaturational temperature of the wild-type protein), amounting to -0.5 +/- 0.4 kcal mol-1 in free energy, whereas the double mutant shows a weak apparent destabilization, +0.8 +/- 0.4 kcal mol-1. As in all our previous studies of mutant proteins, the enthalpy changes produced by these mutations are in general of much larger magnitude than the corresponding free energy changes and frequently of opposite sign.

Calorimetry, Differential Scanning↗
PubMed1992

Synthesis of nigero-oligosaccharides.

Nigerose [alpha-D-Glcp-(1----3)-D-Glcp], nigerotriose, nigerotetraose, and nigeropentaose have been synthesized by chain elongation starting at the reducing end, from the corresponding octa-, undeca-, tetradeca-, and heptadeca-beta-D-acetates, respectively, via thioglycoside-mediated 1,2-cis coupling, using 1,2,4,6-tetra-O-acetyl-beta-D-glucopyranose as the glucosyl acceptor and methyl 2,3,4,6-tetra-O-benzyl-1-thio-beta-D-glucopyranoside, methyl 3-O-allyl-2,4,6-tri-O-benzyl-1-thio-beta-D-glucopyranoside, and methyl O-(2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl)-(1----3)-2,4,6-tri-O- benzyl-1-thio-beta-D-glucopyranoside as the donors.

Carbohydrate Sequence↗