Biomedical subjects

Takeshi Hasegawa

Publications and source records attributed to Takeshi Hasegawa.

At least 19 recordsLinked to original sources

PubMed2007

Sibling cases of Vici syndrome: sleep abnormalities and complications of renal tubular acidosis.

Vici syndrome is a rare congenital disorder characterized by albinism, agenesis of the corpus callosum, and developmental delays. Cardiac complications usually cause poor prognosis. We report sibling cases of Vici syndrome, and address complications of renal tubular acidosis. We also demonstrate the significance of serial examinations of brain natriuretic peptides, and discuss the possible early use of a beta-blocker to control cardiomyopathy. A sleep study including polysomnography indicated functional brainstem involvement, in which muscle atonia during non-rapid sleeping eye movements, and bursts of rapid eye movements increased. These findings provide new clues for medical care of patients with Vici syndrome.

Acidosis, Renal Tubular↗

PubMed2007

Ordered arrays of organometallic iridium complexes with long alkyl chains on graphite.

Iridium(III) fac-tris(2-phenylpyridine) fac-[Ir(ppy)3] complexes equipped with long alkyl chains were prepared to examine their capability to form organized arrays on the surface of highly oriented pyrolytic graphite (HOPG). The molecules form lamellar arrays at the 1-phenyloctane/HOPG interface. From the analysis of the STM images, it was concluded that the molecules align with alkyl chains being interdigitated. Similar lamellar arrays were also obtained at the air/HOPG interface upon drop-casting of toluene solutions. The lamellar structure at the molecular level leads to rectangular two-dimensional crystalline domains a few hundred nanometers long (nanoslips). Infrared external reflection spectroscopy suggested that the adsorbed alkyl chains adopt the trans-zigzag conformation in the nanoslip, although the orientations of the zigzag plane of the alkyl groups are mixed. Cyclic voltammetry indicates fast electron transfer between the adsorbed molecules and the substrate and significant intermolecular electronic interactions. It was found that annealing at high temperatures is an effective method to prepare ordered assemblies more than a few micrometer scale (microslips). The orientations of the nanoslips prepared from the racemic mixture exhibited an apparent 12-fold symmetry, while its optically active enantiomer resulted in more irregular domains with a six-fold symmetry, implying an important role of chirality on packing at the molecular level and on the orientation of the domains at larger scales. When drop-cast from more concentrated solutions than a few hundreds of micromolar, multilayers were obtained, in which the alkyl chains in the molecules are more or less perpendicular to the surface. This structure can be transformed into the nanoslips upon standing.

Journal Article↗

PubMed2006

Analysis of Gibbs monolayer adsorbed at the toluene/water interface by UV-visible partial internal reflection spectrometry.

Gibbs monolayers of lipophilic tetraphenylporphyrinatomanganese(III) and hydrophilic diacid of meso-tetrakis(4-sulfonatopheny)porphyrin adsorbed at the liquid-liquid interface have been analyzed by UV-visible external reflection (ER) and partial internal reflection (PIR) spectra measured at different angles of incidence. The angle-dependent ER and PIR spectra over the Brewster angles (thetaERB and thetaIRB) have readily been measured at the toluene/water interface. As preliminarily expected in our previous study, the present study has first proved that the reflection-absorbance of UV-visible PIR spectra quantitatively agrees with the theoretical calculations for the Gibbs monolayer over thetaIRB. In addition, it has also been proved that the absorbance of the PIR spectra is greatly enhanced in comparison to that of the ATR spectra. The enhancement is caused by an optical effect in the monolayer sandwiched between two phases of toluene and water that have different but refractive indices close to each other. This optical enhancement requires an optically perfect contact between the phases, which is difficult to prepare for a solid-solid contact. At the liquid/liquid interface, however, an ideal optical contact is easily realized, which makes the enhancement as much as the theoretical expectation. The PIR spectrometry will be recognized to be a new high-sensitive analytical tool to study Gibbs monolayer at the liquid/liquid interface.

Acids↗

PubMed2006

Analysis of structurally heterogeneous Langmuir-Blodgett films of folded/unfolded long-chain molecules by infrared multiple-angle incidence resolution spectroscopy.

Infrared multiple-angle incidence resolution spectroscopy (IR MAIRS) has been employed for the structural analysis of a heterogeneous multilayer Langmuir-Blodgett (LB) film of ketomycolic acid (keto-MA). Keto-MA was chosen for the study because the molecule changes its conformation largely, which depends on the layer structure of the LB film: the long alkyl chain with a keto group remains folded when it has no counter layer for interdigitation. IR MAIRS is a surface analytical technique that was originally developed to analyze anisotropic structure in a thin film prepared on an IR transparent material. In the present study, however, a newly found characteristic of MAIRS has been used to discuss the molecular conformation and the interdigitation architecture between two adjacent monolayers. As expected theoretically, the molecular folding was clearly detected as "IR MAIRS shift". Subtraction of the IR MAIRS spectra of single- and triple-monolayer LB film of keto-MA yielded unambiguous results for the interdigitated double layer in the triple-monolayer LB film, and the layer sequence was also revealed.

Journal Article↗

PubMed2006

A miniature ultransonic pump using a bending disk transducer and a gap.

It is known that if a pipe end is faced at a vibrating surface in liquid with a small gap, liquid is suctioned into the pipe. As a miniature configuration, we introduce a bending disk transducer 30 mm in diameter using a ring-shaped PZT element. The disk vibrator is worked at the fundamental resonance frequency of 19 kHz of the bending mode. To optimize the pipe geometry, we experimentally investigated the effect of the outer diameter on the pump performance. As a result, the outer/inner diameter ratio of 3:2 is optimum for the gap smaller than 20 microm. We achieved the maximum pump pressure of 14.8 kPa and the maximum flow rate of 10 ml/min. using the prototype pump.

Journal Article↗

PubMed2006

Molecular orientation analysis of a single-monolayer Langmuir-Blodgett film on a thin glass plate by infrared multiple-angle incidence resolution spectrometry.

Molecular orientation analysis in a single monolayer deposited on a glass substrate has been a difficult matter, since the glass substrate absorbs infrared rays so strongly that the measurements of infrared spectra are difficult to perform, and the single monolayer is not suitable for X-ray diffraction analysis because no periodical structure is available. When a thin glass is used as the substrate, in particular, the infrared analysis becomes more difficult, since optical fringes appear strongly on the absorption spectra due to the multiple reflections in the glass. In the present study, infrared multiple-angle incidence resolution spectrometry (MAIRS) has been employed to remove the fringes from the spectra of single- and five-monolayer Langmuir-Blodgett (LB) films of cadmium stearate deposited on a thin glass plate. The MAIRS in-plane spectra gave quantitatively reliable infrared transmission spectra for both films with little fringes, which made it possible for the first time to analyze the molecular orientation in the single-monolayer LB film on glass. As a result, it has been revealed that the molecule in the single-monolayer LB film on thin glass exhibits a significantly larger molecular tilt angle than those prepared on other substrates such as gold and germanium.

Journal Article↗

PubMed2006

Small bowel strangulation caused by parasitic peritoneal strand.

A 51-year-old woman with a history of eating raw fish over a period of 2 weeks developed a progressive abdominal pain and leukocytosis with signs of small bowel obstruction. Eosinophilia was not detected in the peripheral blood. The patient underwent surgery to clarify the possibility of ileus. Partial small bowel near the ileum was trapped by a peritoneal strand and was strangulated for approximately 30 cm in length with congestion and edema. The removal of the strand easily released the strangulation and the small bowel returned to a normal appearance. Pathologically, the strand consisted of granulomatous inflammation with a wide zone of necrosis containing a dead ghost feature of a parasite in its center. The necrosis was surrounded by palisading spindle cells with largely lymphocytic infiltration and a few eosinophils. In the parasite, there presented the polymyalian type muscle layer, ventricles and Renette cells, which suggested that the parasite is compatible with the third stage larva of Anisakis type I, leading to the diagnosis of ectopic anisakidosis. It should be noted that, on rare occasions, Anisakis larva migrans can form a peritoneal strand with a wide zone of necrosis and cause strangulation ileus, especially in populations with the habit of eating raw fish.

Animals↗

PubMed2006

Spectral simulation study on the influence of the principal component analysis step on principal component regression.

Principal component regression (PCR) is unique in that the principal component analysis (PCA) step is explicitly involved in the central part of the method. In the present paper, the PCA part is examined in order to study the influence of noise in spectra on PCR by spectral simulation. It has been suggested, as a result, that PCR calibration would have a large inaccuracy when the estimated number of basis factors analyzed by the eigenvalue method is less than that by cross-validation, which was studied by use of synthesized spectra. This instability is because the minute noise is largely enhanced by the PCA calculation via the normalization of loadings. At the same time, the noise enhancement by PCA has also been characterized to influence the estimation of basis factors.

Algorithms↗

PubMed2006

[Neurophysiolgical analysis in an 18-month-old girl with Gaucher's disease type 2].

Gaucher's disease is caused by a lack of glucocerebrosidase, and in type 2 various neurological symptoms can occur;however, the detailed pathogenesis of the condition remains undetermined. Here we performed neurophysiological examinations in an 18-month-old girl with Gaucher's disease type 2 to specify the brainstem lesions. Developmental delay occurred from the age of 8 months, and the patient subsequently showed strabismus, loss of head control, failure to thrive and irregular respiration. She was admitted to our hospital at the age of 18 months. A definite diagnosis of Gaucher's disease type 2 was made from the presence of Gaucher cells and reduced glucocerebrosidase activity. Clinically, limited ocular movements, poor facial expression and bulbar palsy indicated disturbances in the nuclei of oculomotor, trochlear, abducent, facial and ambiguous nerves, although magnetic resonance imaging (MRI) failed to visualize any structural changes in the brain including the brainstem. Neurophysiologically, auditory brainstem response and somatosensory evoked potential demonstrated lesions in the cochlear nucleus and medial lemniscus, respectively. On polysomnography, disturbed sleep parameters during rapid eye movement sleep, in addition to the lack of modification of respiratory patterns by sleep stage, suggested dysfunctions in the locus ceruleus, raphe nuclei and pontine reticular formations. It is likely that these neurophysiological tests can be useful to identify functional lesions that are not detectable by MRI, and should help exploit new treatments for child-onset neurodegenerative disorders such as Gaucher's disease.

Evoked Potentials, Auditory↗

PubMed2005

Fibril-like aggregate formation of peptide carboxylate Langmuir films analyzed by surface pressure, surface dipole moment, and infrared spectroscopy.

The fibril formation process of a synthetic peptidolipid compound in a Langmuir monolayer at the air-water interface has been analyzed by surface pressure and surface dipole moment-area isotherms, followed by infrared spectral analysis of related Langmuir-Blodgett films. Thus far, the analysis of randomly oriented molecular assemblies has been a difficult matter, especially for spectroscopic measurements. In the present study, the Langmuir film isotherms were discussed in detail, and they have readily been correlated to the infrared spectra. For the spectral analysis, infrared multiple-angle incidence resolution spectroscopy (MAIRS) was employed, which was compared to the results by conventional techniques. Since the peptide assemblies greatly responded to a metal surface, the reflection-absorption technique was not useful for our analysis. Instead, MAIRS was found to be powerful to reveal the anisotropic structure of the Langmuir films, and a disordered molecular architecture has been revealed via the molecular orientation analysis. As a result, the fibril-like aggregation formation process during the monolayer compression, which was suggested by previous topographical study, has been found to be due to the stiff domain formation in the Langmuir films.

Carboxylic Acids↗

PubMed2005

Leucine fastener formation mechanism between peptide beta-sheets in a monolayer studied by infrared multiple-angle incidence resolution spectroscopy.

A leucine zipper and a leucine fastener formed between peptide molecules have been hypothetical models of a molecular association via interdigitation. As a molecular interaction mechanism, a "leucine zipper" with the aid of an alpha-helix backbone in biological peptides is believed to play an important role in the molecular association, but no experimental evidence to prove the zipping has been reported thus far. In the same fashion, a "leucine fastener" built on the structure of peptide beta-sheets has never been experimentally captured either. In the present study, very fine changes of molecular stress and orientation in monolayers of a synthesized tetraleucine-containing amphiphile before and after the molecular interdigitation have readily been detected by infrared multiple-angle incidence resolution spectroscopy, which was recently developed for the analysis of structural anisotropy in thin materials. It has been suggested that the conventional molecular orientation model of the leucine fastener should be modified, and the backbone structure (parallel beta-sheet in the present study) plays a necessary role for the interlock of the leucine fastener.

Anisotropy↗

PubMed2004

Cartesian-structure analysis in cast films by advanced infrared multiple-angle incidence resolution spectroscopy.

Multiple-angle incidence resolution spectroscopy (MAIRS) has been improved to be an advanced algorithm so that the Cartesian structure in organic thin films can be analyzed. The infrared MAIRS technique was originally proposed as a totally new spectroscopic technique to reveal structural anisotropy in thin films on an infrared-transparent substrate, which yields both in-plane- (IP; X and Y) and out-of-plane (OP; Z)-mode spectra from an identical sample. Since this technique employs an analytical concept based on a signal decomposition of light intensity (not absorbance spectra), the algorithm intrinsically has high potential for further development. In the present study, the theoretically deduced matrix that correlates the light intensity to the angle of incidence has been modified to further decompose the IP-mode spectrum into X and Y components. As a result, anisotropic measurements of infrared spectra of thin film have become possible for the X, Y, and Z directions (Cartesian coordinate) simultaneously. With this advanced algorithm, the Cartesian structural changes in a cast film prepared on a germanium substrate have readily been analyzed, and a change from the biaxial to the uniaxial film structure with aging has spectroscopically been revealed.

Journal Article↗

PubMed2004

Structural analysis of biological aliphatic compounds using surface-enhanced Fourier transform Raman spectroscopy.

The surface-enhanced Raman scattering (SERS) technique for Fourier transform Raman spectrometry is employed to reveal the chemical structure of biological aliphatic compounds consisting of folded, long aliphatic chains. The structural analysis is performed via the measurements of the accordion-vibration modes generated in the ordered, long aliphatic chain. The SERS spectra after subtraction of a background spectrum give segment lengths that are almost perfectly consistent with the chemical structures studied by mass spectrometry. The agreement of the SERS results with those of mass spectrometry suggests the positions of kinks in the long hydrocarbon chain. The combination technique of SERS and mass spectrometry is useful to discuss the structure of folded, long biological lipids.

Adsorption↗

PubMed2004

Systemic growth hormone corrects sleep disturbance in Smith-Magenis syndrome.

Smith-Magenis syndrome (SMS) is a multiple congenital anomaly syndrome characterized by an interstitial deletion of chromosome 17p11.2. Sleep problems such as nocturnal awakening and abnormality in the percentage of rapid eye movement (REM) sleep are frequently observed in patients with SMS, and several medications have been administered to improve the sleep disorders. Here we present a female case of SMS showing early waking and reduction of REM sleep, which were corrected by human growth hormone (GH) replacement for her dwarfism. Also, we report changes in the sleep-wakefulness circadian rhythm and polysomnographical data before and after the start of human GH replacement. It is speculated that GH deficiency could be involved in sleep disturbance in SMS.

Abnormalities, Multiple↗

PubMed2004

[A statistical analysis of epistaxis between outpatients and inpatients].

Although we found several statistical studies on epistaxis, we found no reports discussing clinical differences in nasal bleeding between outpatients and inpatients. We therefore examined 103 inpatients (1998-2001) and 337 outpatients (2001) with epistaxis for gender, age, season, bleeding points, and blood pressure. We then compared these parameters statistically in both groups using Mann-Whitney's U test. The incidence of epistaxis in inpatients was statistically higher in winter than in any other season, and most had uncontrolled borderline hypertension. We concluded that borderline hypertension worsens in winter and that patients with borderline hypertension should be medicated to prevent severe epistaxis.

Adolescent↗

PubMed2003

Aggregation properties of mycolic acid molecules in monolayer films: a comparative study of compounds from various acid-fast bacterial species.

Three kinds of mycolic acids (MAs) (alpha-, keto and methoxy-MAs) extracted from several species of mycobacteria were used to prepare monolayer films on water, and the surface pressure-area (pi-A) isotherms of the monolayers have been compared, so that the monolayer characteristics of the MAs as in cell walls would be revealed, since the monolayer molecular aggregation is related to drug permeability via the molecular packing. It was expected that the limiting molecular areas of the isotherms would be changed only a little, which reflects the minor difference in chemical structure and conformation of the mycobacteria. Nevertheless, the results are largely different from the expectation, and two greatly different patterns of the limiting molecular area have been observed. In a new model for elucidation of the results, two parts in an MA molecule are separately considered, and both contributions to the molecular unfolding by the monolayer compression have been suggested. This model is found to be useful to totally understand the isotherm behaviors of MAs. The relationship between monolayer properties and chemical structures for MAs has been summarized for the first time.

Macromolecular Substances↗

PubMed2003

Analysis by partial reflection spectrometry of protonated tetraphenylporphyrin adsorbed at a liquid-liquid interface.

Visible reflection spectra of diprotonated meso-tetraphenylporphyrin adsorbates spontaneously formed at a dodecane-aqueous sulfuric acid interface have been measured using a home-made device comprising a prism-cell and variable-angle optics. The tilt angle of the pyrrole ring plane was estimated to be 47 degrees from the interface normal by use of an experimentally evaluated molecular density (1.20x10(-10) mol cm(-2)) of the diprotonated molecule in a monolayer form at the liquid-liquid interface. Positive and negative bands have been observed in the p-polarized partial internal reflection (p-PIR) spectra, whose band locations correspond to those in p-polarized external reflection (p-ER) spectra. Nevertheless, the bands in the p-PIR exhibited reversed sign to those of p-ER spectra. These suggest that the surface selection rule of the p-PIR spectrometry has a reversal rule of p-ER and p-PIR can also be used for the analysis of molecular orientation.

Journal Article↗

PubMed2003

Identification of a stable chymase inhibitor using a pharmacophore-Based database search.

In general, serine protease chymase inhibitors readily decompose in plasma. We previously found that thiazolidine-2,4-dione and thiadiazole derivatives are also unstable. Using a pharmacophore-based database search, we identified a benzo[b]thiophen-2-sulfonamide derivative as a stable chymase inhibitor. Finding a lead compound with adequate activity and stability by a pharmacophore-based approach is more efficient than modifying an unstable compound to reduce its instability without simultaneously decreasing its inhibitory activity. Our pharmacophore model of chymase inhibitors suggests that the two hydrophobic interactions in the S1 and S1' regions and the two H-bonding interactions between them play important roles in chymase inhibitors.

Animals↗