Biomedical subjects

T Handa

Publications and source records attributed to T Handa.

At least 55 records · Page 3Linked to original sources

PubMed1995

Regulation of phospholipase D activity by neutral lipids in egg-yolk phosphatidylcholine small unilamellar vesicles and by calcium ion in aqueous medium.

Hydrolysis activity of phospholipase D from Streptomyces chromofuscus (PLD) was studied in small unilamellar vesicles (SUV) of egg yolk phosphatidylcholine (PC). The enzyme was associated with PC-SUV in a Ca(2+)-dependent manner. Both apparent maximum velocity, Vmax(app), and reciprocal of apparent Michaelis constant, i.e., apparent binding constant, 1/Km(app), increased with Ca2+ concentration, and the maximum values of these kinetic parameters were obtained at about 20 microM Ca2+. Incorporation of 1,2-diacylglycerol (DAG), cholesterol (Chol) or alpha-tocopherol (Toc) into PC-SUV induced shift of the antisymmetric PO2- stretching band of PC to lower frequency. The neutral lipids in SUV brought about increase of the Vmax(app) value (Yamamoto et al. (1993) Biochim. Biophys. Acta 1145, 293-297). On the basis of these findings we discussed the regulation of PLD activity in terms of the Ca(2+)-dependent complex formation of PLD with SUV, and the enhancement of susceptibility of the P-O bond in PC molecule by neutral lipids.

Calcium↗

PubMed1995

[Free rectus abdominis muscle perforating artery flaps for reconstruction of the head and neck defects].

During the past eight years, tissue defects of the head and neck region in a total of 45 patients were repaired with free rectus abdominis muscle perforating artery flaps. These flaps are subclassified into (1) reduced musculocutaneous flaps, (2) thin reduced musculocutaneous flaps, (3) paraumbilical perforator-based flaps, and (4) thin paraumbilical perforator-based flaps. The advantages of these flaps are as follows. Since the flaps involve no or only a small portion of the rectus abdominis muscle, (1) the muscle can be left intact on the abdominal wall, and (2) a thin flap can be easily created by simple defatting of the flap. These flaps overcome the major disadvantages of the conventional rectus abdominis musculocutaneous flap, i.e., bulkiness of the flap and frequent postoperative abdominal herniation. The territory of the thin flaps is within 10 cm around the perforator. These flaps are suitable for defects in the head and neck region, because simultaneous flap elevation is possible at the time of tumor resection. Paraumbilical perforator-based flaps are suitable for young females and elderly patients.

Aged↗

PubMed1995

[Activities of antipseudomonal agents against clinical isolates of Pseudomonas aeruginosa].

Using clinically isolated 114 strains of Pseudomonas aeruginosa that were collected from April to October 1994, activity of antipseudomonal agents against these organisms was determined using the method of liquid microdilution. In addition, antimicrobial activities of the agents were graded according to serological groups of organisms. The results of this study are summarized as follows. 1. Many strains of P. aeruginosa were isolated mainly from sputum, pus and urine. 2. Serological group G organisms of sputum origin, group I of pus and bile origin, and group E of urine origin were isolated most frequently. 3. The most powerful antipseudomonal agent was cefclidin. Its MIC50 and MIC90 were 0.78 and 6.25 micrograms/ml, respectively. The second most powerful agent was ciprofloxacin whose MIC50 and MIC90 were 0.39 and 12.5 micrograms/ml, respectively. 4. The proportions of resistant strains ranged from 0.9% for cefclidin to 40.4% for ofloxacin. The antipseudomonal agents to which 30% or more of strains were resistant were cefpirome, gentamicin and ofloxacin. 5. Cefclidin showed the most powerful activity against strains that were resistant to ceftazidime, imipenem, gentamicin and ofloxacin. Its MIC90 against all strains resistant to ceftazidime, gentamicin and ofloxacin was 6.25 micrograms/ml. The MIC90 of cefclidin and tobramycin against imipenem-resistant strains was 3.13 micrograms/ml. 6. Group E organisms were found among strains resistant to ceftazidime, gentamicin and ofloxacin at high rates, but no group E strains were found among imipenem-resistant organisms. 7. Agents with highest activities by serological group of organisms were cefclidin against group A, tobramycin and ciprofloxacin against group B, imipenem against group E, ciprofloxacin against group G, and cefclidin and ciprofloxacin against group I.(ABSTRACT TRUNCATED AT 250 WORDS)

Anti-Infective Agents↗

PubMed1994

Effects of cholesterol and cholesteryl oleate on lipolysis and liver uptake of triglyceride/phosphatidylcholine emulsions in rats.

Emulsions composed of soy bean triglyceride (TG), egg yolk phosphatidylcholine (PC), cholesterol (Chol) or cholesteryl-oleate (CO), labeled with a cholesteryl ether (3H-CHE) and a triglyceride (14C-TO), were injected into rats. 14C-TO was removed from plasma faster than 3H-CHE. The 14C-labeled moiety is cleaved by digestion of the TG in the emulsion in plasma and is removed to the endothelial cells (lipolysis). In contrast, the 3H-label remains stably associated and represents circulating emulsion particles. The majority (90%) of the 3H-label disappearing from the plasma accumulated in the liver for all types of emulsions. On the basis of these observations, the lipolysis and the removal of emulsion particles to organs (mainly liver) were determined: 30 mole percent of cholesterol (Chol) at the TG-PC emulsion surface markedly retarded organ uptake, but the effect on lipolysis was rather small; 20 mole percent of cholesteryl oleate (CO) in the TG-PC emulsion cores delayed both organ uptake and lipolysis, and induced a rapid increase in organ uptake rate after the initial delay accompanying the gradual progress of lipolysis. Lipolysis led to the enrichment of the cores with CO. Replacement of the core TG by CO, however, induced strong suppression of the liver uptake. These results show that the lipid composition at both surface and core of emulsion particles is a crucial factor in metabolism in the rat.

Animals↗

PubMed1994

Study on the elbow movement produced by functional electrical stimulation (FES).

Functional electrical stimulation (FES)-induced movements of the upper extremity using the electromyography (EMG)-based stimulation data, which were created on the basis of EMG analysis of elbow flexion and extension in a normal human subject, were examined. As a result of the FES to the elbow flexors and extensors in another normal subject, smooth and reproducible elbow flexion and extension were controlled. This result seems to indicate not only an advantage of EMG-based stimulation data in the FES but also a great potential of FES as a new technique for the functional anatomy of the human extremities.

Elbow Joint↗

PubMed1994

Primary Ewing's sarcoma of the skull base with intracerebral extension--case report.

A 32-year-old female presented with an uncommon primary Ewing's sarcoma of the skull involving the middle cranial fossa with an extremely unusual extension into the cerebral parenchyma. She was treated with surgical excision, irradiation, and chemotherapy. Two years after surgery she demonstrated no evidence of local recurrence or distant metastasis. Ewing's sarcoma of the skull may achieve a better survival rate under adequate management than this lesion in other sites.

Adult↗

PubMed1993

Effects of 1,2-diacylglycerol and cholesterol on the hydrolysis activity of phospholipase D in egg-yolk phosphatidylcholine bilayers.

Effects of cholesterol (Chol) and 1,2-diacylglycerol (DAG) on the hydrolysis activity of phospholipase D (from Streptomyces chromofuscus) were studied in small unilamellar vesicles (SUV) of egg-yolk phosphatidylcholine (PC). 1,2-Diacylglycerol used here is derived from PC. Choline produced in the reaction was monitored by using a choline oxidase-oxygen electrode. Addition of 18.3 mol% Chol into SUV (2 mM PC) led to a small increase in the reaction rate. On the other hand, 18.3 mol% DAG in SUV brought about a 5-6-fold rate of choline production. The apparent maximum velocity, Vmax(app), increased by addition of DAG and Chol in SUV. In PC/Chol-SUV, the effect of increase in Vmax(app) was largely compensated by the increase in the apparent Michaelis constant, Km (app). The Chol and DAG molecules did not have significant effects on the kinetic parameters, when PC was solubilized in the micelles of heptaethylene glycol dodecyl ether. The effects of Chol and DAG are, therefore, not due to specific ones on the enzyme itself, but rather upon the bilayer-organization of the substrate. We discuss the activation of phospholipase D in terms of the influences of DAG and Chol on the structure of hydrophilic region and fluidity of the bilayers.

Cholesterol↗

PubMed1993

Contribution of meningeal arteries to cerebral arteriovenous malformations.

We studied 52 patients with cerebral arteriovenous malformations (AVMs) by selective angiography and found that half received supply from meningeal branches of the external carotid artery. The frequency of meningeal arterial contribution was significantly higher in superficial AVMs, especially in the temporal, parietal and occipital regions. Larger lesions and higher shunt with steal phenomena on angiography were other factors favouring a meningeal arterial contribution. Diffuse AVMs with pial arterial networks around the nidus commonly received meningeal blood supply. In the past, meningeal feeders have been thought to be congenital, but this study suggests that they may develop during growth of the AVM.

Adolescent↗

PubMed1993

Dural carotid cavernous sinus fistula presenting as isolated oculomotor nerve palsy.

We report five patients with dural carotid cavernous sinus fistula presenting with isolated oculomotor nerve palsy. All patients were older women with a fistula derived from the internal carotid artery, who had early filling of the supero-posterior cavernous sinus, followed by drainage posteriorly into the inferior petrosal sinus, with low shunt flow. The hypothesized pathogenesis was nerve compression by an expanding sinus, or ischemic neuropathy secondary to venous congestion or arterial steal. Dural carotid cavernous sinus fistula must be considered in patients presenting with isolated oculomotor nerve palsy.

Aged↗

PubMed1993

Eutectic mixed monolayers in equilibrium with phospholipid-bilayers and triolein-liquid phase.

Triolein (TO) and phospholipids (egg yolk phosphatidylcholine, egg yolk phosphatidylethanolamine, and bovine brain phosphatidylserine) had low mutual solubilities and separated into the TO-liquid phase and phospholipid-bilayers. Spreading pressures of the TO-phospholipid mixture (i.e., surface pressures of the mixed monolayer in equilibrium with the phase-separating lipid mixture) at the air/saline interface were independent of the lipid composition. On the other hand, collapse pressures of the mixed monolayer of TO and phospholipid (i.e., surface pressures of the mixed monolayer in equilibrium with the TO-liquid phase) at the interface changed with the monolayer composition and were lower than the spreading pressure. The experimental data indicated the spreading and collapse pressures as offering a phase diagram for the presence of equilibrium between the mixed monolayer, the phospholipid-bilayers and the TO-liquid phase. The diagram showed that TO and the phospholipids were miscible in the mixed monolayer, forming an eutectic mixed monolayer. When the mixed monolayer initially had the eutectic composition, no collapse of the monolayer was detected until the surface pressure reached the value of the spreading pressure. No specific complex between TO and the phospholipid is required to explain the stability and collapse of the mixed monolayers. The bulk immiscibility of the lipids elucidated by the spreading pressure-measurements, immediately leads to the phase behaviors observed.

Animals↗

PubMed1993

Effects of cholesterol on the miscibility of synthetic glucosamine diesters in lipid bilayers and the entrapment of superoxide dismutase into the positively charged liposomes.

Methyl-D-glucosamine-3,6-dilauroyl, dimyristoyl, dipalmitoyl or distearoyl esters were synthesized as positively charged lipids. They were incorporated into phosphatidylcholine liposomal membranes and the entrapment of superoxide dismutase (SOD) into the liposomes was attempted. The efficiency of the SOD-entrapment into the positively charged multilamellar vesicles (MLVs), comprising egg yolk phosphatidylcholine and synthetic glucosamine diesters, was enhanced by the addition of cholesterol to the membranes. A differential scanning calorimetric study showed that the miscibility (solubility) of glucosamine diesters in phosphatidylcholine-bilayers increased on the addition of cholesterol to the membranes. Cholesterol assisted in the mixing of phosphatidylcholines with positively charged glucosamine diesters and increased the positive charges on the liposomal membranes. This was confirmed by incremental increases in the zeta-potential of liposomal membranes with an increase in the cholesterol content. Entrapment of SOD thus became more efficient due to the enhanced electrostatic attraction between the positively charged membranes and the negatively charged SOD, and/or the electrostatic repulsive interactions between positively charged membranes; the latter interactions induced a thickening of the water layer in MLVs.

Cholesterol↗

PubMed1993

Evaluation of pressure changes in feeding arteries during embolization of intracerebral arteriovenous malformations.

The pressure in 47 arteries feeding 21 arteriovenous malformations (AVM's) was investigated during transarterial embolization using a Tracker-18 microcatheter. On average, systolic pressure increased by 22 mm Hg. In AVM's with single or few feeders, embolization was usually achieved well; in contrast, giant AVM's with multiple feeders and a large arteriovenous shunt were poorly embolized. However, large AVM's with well-demarcated components may be reduced by embolization to an appropriate size for surgery or stereotactic radiation therapy. It was found that the feeding artery pressure increased significantly more in well-embolized than in poorly embolized cases. Measurements of the feeding artery pressure clarified the hemodynamics of AVM's and facilitated more successful embolization.

Adolescent↗

PubMed1992

Resonance Raman study on the active-site structure of a cooperative hemerythrin.

Resonance Raman spectra were observed for the oxy and azidomet forms of a cooperative hemerythrin (Hr) isolated from Lingula unguis and a noncooperative Hr from Siphonosoma cumanense. The O-O stretching frequency of the oxy derivative of the L. unguis Hr was lower in the high-affinity form generated at pH 7.6 than in the low-affinity form generated at pH 6.2, while that of the S. cumanense Hr did not change at those two pH values. The Fe-O-Fe symmetric stretching mode of L. unguis azidomet-Hr exhibited a frequency shift between pH 7.6 and 6.2, while that of S. cumanense was not shifted. However, the corresponding band of the oxy form did not show a pH-dependent frequency change. Therefore, it is noted that the azidomet form is not a suitable model for studying a mechanism of cooperativity, contrary to the structural similarity between the oxy and azidomet forms. The Fe-O2 as well as Fe-N3 stretching frequencies were found to have no relation with the oxygen affinity. Upon exchange of solvent from H2O to D2O, the O-O and Fe-O2 stretching modes of L. unguis Hr were shifted to higher and lower frequencies, respectively, and their magnitudes were the same for the high- and low-affinity forms. The same frequency shifts were observed for S. cumanense Hr.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Monolayer-bilayer equilibrium of phospholipid: stabilization of neutral lipid droplets in aqueous medium and catabolism of plasma lipoproteins.

Phospholipid spreads as monolayer at air/water and oil/water interfaces. Interfacial pressure of the monolayer in equilibrium with a definite bulk phase of the lipid, (equilibrium) spreading pressure, depends on lyotropic and thermotropic polymorphic state of the lipid bulk phase. Phosphatidylcholine (PC) in hydrated liquid crystalline state (bilayers in L alpha state) gives an appreciably large value of spreading pressure, 45-46 mN/m. Monolayer-bilayer equilibrium of a neutral lipid-phospholipid mixture is determined by miscibilities of the lipids in mixed monolayer, PC bilayer and bulk (liquid or solid) phase of the neutral lipid. A neutral lipid of limited solubility in PC bilayer forms a separate phase in aqueous medium. The phase is stabilized as small particles in the medium by PC monolayer at the particle surface. The monolayer is in equilibrium with the bilayer. This sort of equilibrium plays important roles in formation and catabolism of triglyceride- and cholesteryl ester-rich lipoprotein particles in animal plasma. The equilibrium is a critical factor also in stabilization of aqueous dispersion of lipophilic vitamin (neutral lipid). Coexistence of emulsion particles (neutral lipid core covered with PC monolayer) and vesicles made of PC bilayer are observed in a stable dispersion.

Animals↗

PubMed1992

Lateral interactions of pig apolipoprotein A-1 with egg yolk phosphatidylcholine and with cholesterol in mixed monolayers at the triolein-saline interface.

Interfacial tensions of egg yolk phosphatidylcholine (PC) and cholesterol monolayers adsorbed at the triolein-saline interface were measured in the presence and absence of pig apolipoprotein A-1 (apoA-1) in the saline phase. In the absence of apoA-1, the adsorptions of PC and cholesterol at the interface from the triolein phase are cooperative, showing large lateral attractive interactions between the PC molecules and the cholesterol molecules in the monolayer. In the presence of apoA-1, the PC adsorption is anti-cooperative, indicating strong lateral attractive interactions between the PC and the apoA-1 molecules, i.e., apparently, repulsive lateral interactions between the PC molecules. On the other hand, lateral interactions of very low magnitude are observed between the cholesterol and apoA-1 molecules in the monolayer. Values of the lateral interaction energy are evaluated from the adsorption data by the Defay-Prigogine-Flory theory of monolayers. The large difference in lateral interaction energy with apoA-1 between PC and cholesterol in a mixed monolayer is discussed in connection with current problems in lipoprotein catabolism: reverse cholesterol transport, alterations in affinity of lipid particles to apoA-1, and formation of high-density lipoproteins and abnormal lipoproteins.

Adsorption↗

PubMed1992

Histopathological study of balloon embolization: silicone versus latex.

Bilateral, symmetrical, experimental aneurysms were produced with anastomosed vein flap in the carotid arteries of 24 mongrel dogs. Aneurysms were occluded with latex or silicone balloons on each side and observed angiographically from 2 weeks to 2 months. A histopathological study was performed subsequently using light and scanning electron microscopy. Rupture after balloon embolization occurred in five aneurysms; all of which were incompletely occluded by a silicone balloon. On subsequent angiograms, four silicone balloons and one latex balloon were found to have migrated into the aneurysm, resulting in aneurysmal expansion. Parent artery occlusion was more common with latex balloons than silicone balloons. Histopathologically, residual fresh thrombi, decreased proliferation of fibroblasts within the aneurysmal cavity, and poor endothelialization were present around the silicone balloon. These results suggest that the intra-aneurysmal organization, as seen in the aneurysm occluded by the silicone balloon, will be delayed because the balloon is not fixed within the aneurysm, and that this free-floating and rotating balloon causes repeated trauma to the aneurysm wall, contributing to subsequent enlargement and rupture of the aneurysm. The superior antithrombogenic nature of silicone may be responsible for the bias of such phenomena toward the silicone balloon.

Aneurysm↗

PubMed1992

Computer-assisted gait training (CAGT) of hemiparetic stroke patients: whose recovery is most predictable?

Maximum walking speed for 10 m distance of 109 hemiparetic stroke patients was examined every week for 7 weeks after starting computer-assisted gait training (CAGT), and the relation between the time since stroke onset (x) and the maximum walking speed (y) was approximated by a hyperbolic function, y = A-B/x. The patients were divided into two groups, 91 cases with a significant fit of the function (fit group) and 18 without fit (non-fit). The gain of maximum walking speed during 7 weeks was larger in the fit group, compared to the non-fit. Computed tomography examination revealed that the significant fit was mostly expected in patients with the caspular lesion without the cortical involvements except the frontal. The time at which the maximum walking speed of the patients belonging to the fit group would reach the midst of the estimated full recovery of gait can be predicted at the start of CAGT (R2 = 0.955), using two variables: the time since stroke onset and the maximum walking speed.

Brain↗

PubMed1992

Vascular endoscopy for intravascular surgery--an experimental study.

A combination of endoscope and high-pressure saline irrigation system was tested in the occlusion of experimental aneurysms, and angioplasty and fibrinolysis of vascular occlusive lesions in canine femoral arteries. Endoscopy provided detailed information about the aneurysmal orifice and lumen and aided balloon placement and detachment. Endoscopy visualized the dynamic changes accompanying thrombolysis and the fine intimal injury due to angioplasty invisible on angiography. Vascular endoscopy is valuable for pre-, intra-, and postoperative evaluation of intravascular interventions.

Angiography↗