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H Minamikawa

Publications and source records attributed to H Minamikawa.

At least 19 recordsLinked to original sources
PubMed2001

Hydration and molecular motions in synthetic phytanyl-chained glycolipid vesicle membranes.

Proton permeation rates across membranes of a synthetic branch-chained glycolipid, 1,3-di-O-phytanyl-2-O-(beta-D-maltotriosyl)glycerol (Mal3(Phyt)2) as well as a branch-chained phospholipid, diphytanoylphosphatidylcholine (DPhPC) were lower than those of straight-chained lipids such as egg yolk phosphatidylcholine (EPC) by a factor of approximately 4 at pH 7.0 and 25 degrees C. To examine whether degrees of water penetration and molecular motions in Mal3(Phyt)2 membranes can account for the lower permeability, nanosecond time-resolved fluorescence spectroscopy was applied to various membranes of branch-chained lipids (Mal3(Phyt)2, DPhPC, and a tetraether lipid from an extremely thermoacidophilic archaeon Thermoplasma acidophilum), as well as straight-chained lipids (EPC, 1-palmitoyl-2-oleoyl-phosphatidylcholine (POPC), and digalactosyldiacylglycerol (DGDG)) using several fluorescent lipids. Degrees of hydration of glycolipids, Mal3(Phyt)2, and DGDG were lower than those of phospholipids, EPC, POPC, and DPhPC at the membrane-water interfaces. DPhPC showed the highest hydration among the lipids examined. Meanwhile, rotational and lateral diffusive motions of the fluorescent phospholipid in branch-chained lipid membranes were more restricted than those in straight-chained ones. The results suggest that the restricted motion of chain segments rather than the lower hydration accounts for the lower proton permeability of branch-chained lipid membranes.

Diffusion↗
PubMed2000

Interglycolipid Membrane Interactions: pH-Dependent Aggregation of Nonionic Synthetic Glycolipid Vesicles.

Large unilamellar vesicles composed of a nonionic synthetic glycolipid, 1,3-di-O-phytanyl-2-O-(beta-D-maltotriosyl)glycerol exhibited a pH-dependent aggregation-disaggregation process; vesicle aggregation occurred in a lower pH region and vesicle disaggregation occurred in a higher pH region. This process was almost reversible and the aggregation threshold pH increased as NaCl concentration increased. Electrophoretic mobility measurements revealed that the glycolipid vesicles are negatively charged in the range pH 1.6-13. The change in zeta-potentials as functions of pH and NaCl concentration could be well described by the Gouy-Chapman expression of the surface charges with an assumption that the interfacial charges arise from the "adsorption" of OH(-) at the vesicle-water interface and the dissociation of hydroxyl groups of the sugar headgroup in a higher pH regime (>pH 10). The pH-dependent aggregation process was reasonably well described by the classical DLVO theory. Thus, the double-layer repulsive forces appear to be a major factor in stabilizing the glycolipid vesicle suspension. Copyright 2000 Academic Press.

Journal Article↗
PubMed1999

Synthetic phytanyl-chained glycolipid vesicle membrane as a novel matrix for functional reconstitution of cyanobacterial photosystem II complex.

The vesicles composed of synthetic phytanyl-chained glycolipid and natural sulfoquinovosyldiacylglycerol at 9:1 molar ratio were successfully applied to functional reconstitution of photosystem II complex (PS II) from a thermophilic cyanobacterium. The synthetic glycolipid employed was one of our model archaeal diether lipids, 1, 3-di-O-phytanyl-2-O-(beta-D-maltotriosyl)glycerol. The light-induced oxygen-evolving activity of PS II reconstituted in the glycolipid vesicles was approximately 6-fold higher than that reconstituted in several phosphatidylcholine vesicles. The present results reveal the first evidence that a well-designed synthetic glycolipid is effective for the functional reconstitution of complicated and labile membrane protein complexes, such as PS II.

Cyanobacteria↗
PubMed1999

Formation and characterization of planar lipid bilayer membranes from synthetic phytanyl-chained glycolipids.

The formability, current-voltage characteristics and stability of the planar lipid bilayer membranes from the synthetic phytanyl-chained glycolipids, 1, 3-di-O-phytanyl-2-O-(beta-glycosyl)glycerols (Glc(Phyt)(2), Mal(N)(Phyt)(2)) were studied. The single bilayer membranes were successfully formed from the glycolipid bearing a maltotriosyl group (Mal(3)(Phyt)(2)) by the folding method among the synthetic glycolipids examined. The membrane conductance of Mal(3)(Phyt)(2) bilayers in 100 mM KCl solution was significantly lower than that of natural phospholipid, soybean phospholipids (SBPL) bilayers, and comparable to that of 1,2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) bilayers. From the permeation measurements of lipophilic ions through Mal(3)(Phyt)(2) and DPhPC bilayers, it could be presumed that the carbonyl groups in glycerol backbone of the lipid molecule are not necessarily required for the total dipole potential barrier against cations in Mal(3)(Phyt)(2) bilayer. The stability of Mal(3)(Phyt)(2) bilayers against long-term standing and external electric field change was rather high, compared with SBPL bilayers. Furthermore, a preliminary experiment over the functional incorporation of membrane proteins was demonstrated employing the channel proteins derived from octopus retina microvilli vesicles. The channel proteins were functionally incorporated into Mal(3)(Phyt)(2) bilayers in the presence of a negatively charged glycolipid. From these observations, synthetic phytanyl-chained glycolipid bilayers are promising materials for reconstitution and transport studies of membrane proteins.

Animals↗
PubMed1999

Self-assembly of synthetic glycolipid/water systems.

Glycolipids (amphiphiles that bear oligosaccharides as their hydrophilic headgroups) are of importance both scientifically and technically. This review describes recent advances in our understanding of the molecular correlations in phase behavior in aqueous glycolipids over the past several years. In the first part, we discuss how headgroup stereochemistry affects the phase behavior of glycolipids both in two- and three-dimensional systems. In the second part, we discuss the effects of alkyl chain structure and phase behavior of phytanyl-chained glycolipid/water systems. The physical properties of glycolipid/water systems depend strongly on the inter-headgroup interactions that are related to such factors as stereochemistry (conformation) and size of headgroups, type of sugar residues involved, alkyl chain structure, etc. Thus, apart from the conventional concept like 'hydrophilic/lipophilic balance', explicit accounts of headgroup interactions are crucial to control the particular glycolipid/water system concerned. This is in marked contrast to the conventional amphiphile/water systems where the inter-headgroup interactions are in most cases simply repulsive.

Biopolymers↗
PubMed1994

Synthesis of 1,3-di-O-alkyl-2-O-(beta-glycosyl)glycerols bearing oligosaccharides as hydrophilic groups.

A novel series of synthetic glycolipids, 1,3-di-O-alkyl-2-O-(beta-glycosyl)glycerols, and their efficient synthetic route were proposed. These glyceroglycolipids were synthesized in good overall yields and stereoselectivity in five steps via trichloroacetimidate glycosylation with 1,3-di-O-alkylglycerols. This route was applied to prepare the glycolipids bearing a cello- or malto-oligosaccharide with a definite number of sugar residues from one to six. Thin-layer chromatography, elemental analysis, nuclear magnetic resonance spectroscopy and infrared absorption spectroscopy confirmed that these glycolipids were chemically pure compounds.

Carbohydrate Sequence↗
PubMed1994

Combined therapy with arbekacin and fosfomycin for methicillin-resistant Staphylococcus aureus infections.

We examined the clinical efficacy of a combination of arbekacin and fosfomycin in the treatment of various methicillin-resistant Staphylococcus aureus (MRSA) infections. The combination of arbekacin plus fosfomycin displayed 65.4% (17/26) clinical efficacy and 65.4% (17/26) bacteriological efficacy. This combination thus appeared to be an effective regimen for the treatment of MRSA infections. However, its bacteriological efficacy against concomitant Pseudomonas aeruginosa strains was only 16.7% (1/6). In addition, in 4 episodes of superinfection involving P. aeruginosa strains developed during the combination therapy.

Aminoglycosides↗
PubMed1991

Neurography of the brachial plexus in the thoracic outlet syndrome.

Neurography of the brachial plexus was carried out in 180 patients with suspected thoracic outlet syndrome and in 30 normal subjects. In the thoracic outlet syndrome, abnormalities were found in 85% of suspected cases. Narrowing was seen in the scalenus triangle (30%), in the costoclavicular-space (75%) and at the subcoracoid level (6%). Translucent lines were present in 53%, and in 28% of the controls. After successful operation, the appearances returned to normal. Neurography was helpful in making the diagnosis and in determining the correct surgical procedure.

Adult↗
PubMed1985

An adult case of arrhythmogenic right ventricular dysplasia.

A forty-year-old man was admitted to our hospital because of dizziness, palpitations and an oppressive feeling in the precordium. Physical examination was normal. A chest roentgenogram revealed mild cardiomegaly and the electrocardiogram showed ventricular tachycardia of a left bundle branch block configuration which was terminated by the intravenous injection of procainamide. During sinus rhythm the electrocardiogram showed incomplete right bundle branch block, PQ prolongation and inverted T waves in leads V1 through V3. Two-dimensional echocardiography revealed only moderate right ventricular dilatation. Right ventricular angiography showed severe right ventricular dilatation and hypokinesis of the right ventricular apex and pulmonary artery infundibulum. From these characteristics signs we concluded that this adult patient had arrhythmogenic right ventricular dysplasia (ARVD), suggesting that this condition is not confined to children but may occur in adults as well.

Adult↗
PubMed1983

[Cardiac manifestation of the mucopolysaccharidoses: periodical echocardiographic evaluation in six cases].

Serial non-invasive studies including echocardiography were performed for the evaluation and follow-up of the cardiac lesions in six cases with genetic mucopolysaccharidoses. These cases were classified by the enzyme assay into one case of Scheie syndrome, three of Hunter syndrome, one of Sanfilippo syndrome and one of Maroteaux-Lamy syndrome. The echocardiographic examination revealed the most striking change in the mitral valve, which was progressive with increase of the age in most cases. The mitral valve echo was dense and multilayered with a decreased diastolic descent rate (DDR) in the M-mode echocardiogram, and its thick leaflets showed diminished opening on the two-dimensional echocardiogram. The aortic valve echo was also dense in three cases inducing one case with the prolapse of the non-coronary cusp into the left ventricular (LV) cavity. The pulmonary and tricuspid valves showed an unremarkable change, although the echocardiographic signs of pulmonary hypertension was observed in two cases. Diffuse hypertrophy of the interventricular septum and LV posterior wall was observed in five cases and apical hypertrophy was found in a case of Hunter syndrome (Case 2). Parameters of the LV contractility showed almost normal values but the distensibility of the LV posterior wall was impaired in two cases, suggesting stiffness of the cardiac muscle. Although no ischemic change was observed on the electrocardiogram, the echo density of coronary artery wall was not uniform on the two-dimensional echocardiogram and dilated coronary artery was found in two cases. Phonocardiograms disclosed an aortic regurgitant murmur in one case and an apical mitral regurgitant murmur in two cases. In one case of Scheie syndrome, a pansystolic murmur (Levine 3/6) and a mid-diastolic rumble (Levine 2/6) were present at the age of 15 and 16, but after the transient increase in the loudness these disappeared at the age of 18 and only an ejection systolic murmur is audible at the present time, while the mitral valve showed a progressive limitation of the movement on the two-dimensional echocardiogram. Contrary to the reduced DDR and diminished opening of the mitral valve in 3 cases, neither diastolic rumble nor opening snap was recognized in the phonocardiogram. The echocardiographic findings seemed to reflect the patho-anatomical manifestation of this disease, and thus, the periodical echocardiographic evaluation is rewarding to assess the cardiac lesions and their progression in mucopolysaccharidoses.

Adolescent↗
PubMed1983

[Significance of the fourth heart sound in patients with angina pectoris].

To determine the physiological significance of the fourth heart sound at rest in patients with angina pectoris without previous myocardial infarction, the tension time index (TTI) and the ratio of the diastolic pressure time index (DPTI) to (DPTI/TTI) were calculated from the recordings of the left ventricular and aortic pressure curves. Thirty patients were subjected to the study and they were classified into two groups: Group A consisted of 15 patients with the fourth heart sound and Group B of 15 patients without it. Nine cases of atypical chest pain without the fourth heart sound served as control group. TTI was significantly higher in Group A than in Group B (p less than 0.01) and control group (p less than 0.01) (2,552 +/- 489 mmHg X sec/min in Group A, 2,024 +/- 425 mmHg X sec/min in Group B, and 2,023 +/- 209 mmHg X sec/min in control group). DPTI/TTI was significantly lower in Group A than in Group B (p less than 0.01) and control group p less than 0.001) (1.16 +/- 0.19 in Group A, 1.55 +/- 0.39 in Group B, and 1.45 +/- 0.15 in control group). Left ventricular systolic pressure tended to be higher in Group A than in Group B and control group. There was no significant difference in left ventricular end-diastolic pressure, left ventricular ejection fraction and cardiac index among three groups and there was no difference in the prevalence of left ventricular asynergy on left ventriculography between Group A and Group B.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗