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Biomedical subjects

K Nakazato

Publications and source records attributed to K Nakazato.

At least 37 records · Page 2Linked to original sources
PubMed1997

Binding of methamphetamine to serum albumin in various species in vitro.

While drugs from experimental animals provide very important information, it is also true that data differ from species to species, and that data from experimental animals cannot be applied directly to humans. The binding parameters of serum albumin from various animal species and methamphetamine were investigated in vitro by the Scatchard method. The Scatchard plots for the binding of serum albumin and methamphetamine were classified into three patterns: straight lines for human and rat serum albumin; downwardly convex curves for bovine and rabbit serum albumin; and upwardly convex curves for horse, mouse and chicken serum albumin. Hill coefficients were calculated for binding in which the Scatchard plots were upwardly convex curves and for guinea pig serum albumin. The results suggested the existence of positive cooperativity between the methamphetamine binding sites on serum albumin from the horse, mouse, chicken and guinea pig. Furthermore, the process of methamphetamine binding to human serum albumin appears to differ from the process for all experimental animals except the rat, and there are also differences between the binding processes in the various experimental animals.

Animals↗
PubMed1997

Lack of evidence for the transmission of JC polyomavirus between human populations.

Human polyomavirus JC virus (JCV), the causative agent of progressive multifocal leukoencephalopathy, is ubiquitous in humans, infecting children asymptomatically then persisting in renal tissue. Since JCV DNA can readily be detected from urine, it should be a useful tool with which to study the mode of virus transmission in humans. Based on this notion, we examined the extent to which JCV was transmitted from the American to Japanese populations in Okinawa Island, Japan. (A population of about 50 000 American soldiers and families have been stationed in Okinawa since 1945.) Four JCV types (A to D) were identified in American populations in U.S.A., whereas only type B was prevalent in elder Japanese in Okinawa who had reached adulthood by 1945. Thus, types A, C, and D served as indicators of the transmission of JCV from American to Japanese populations. We then examined whether types A, C, and D were detectable in Japanese in Okinawa aged 30-50 years who may have been in contact with Americans during childhood. However, all the 125 isolates from the younger Japanese population were type B without exception. From this finding, we concluded that JCV is rarely transmitted between human populations.

Adult↗
PubMed1997

Androgyny and successful adaptation across the life span among Japanese adults.

The purposes of this study were (a) to examine androgynous, masculine, feminine, and undifferentiated traits of Japanese respondents ranging in age from 13 to 92 years old, as measured by the Bem Sex Role Inventory and (b) to measure the relationship between androgyny and successful adaptation. The respondents were randomly sampled from Yokohama City (634 men, 802 women) and were classified by age as follows: 13-24 years old, 25-44 years old, 45-64 years old, and 65 and older. Successful adaptation was measured by the Rosenberg Self-Esteem Scale, the CES-Depression Scale, the Hassles Scale, and by subjective health. No age effects for androgyny and masculinity were found in men. The undifferentiated type was predominant in adolescents, both male and female. In the oldest age group, most women were classified as feminine. Adaptation of the four sex roles was different depending on sex and age. Throughout the life span of both sexes, there was a relationship between androgyny and successful adaptation. Self-esteem and subjective health seemed to be the most effective predictors of adaptation.

Adaptation, Psychological↗
PubMed1997

Isolated collagen IV retains the potential to form an 18-nm sided polygonal meshwork of the lamina densa.

Polygonal meshworks were revealed in the aggregates reconstituted from isolated collagen IV as well as in the lamina densa of mouse pancreas by the quick-freezing and deep-etching technique. Collagen IV solution with acetic acid from the bovine lens capsules and that isolated from the pepsin-solubilized fraction of human placenta reconstituted polygonal meshworks, which were dimensionally similar to the meshwork seen in the lamina densa of mouse pancreas. The average lengths between branching points in the lamina densa, and the meshworks of collagen IV derived from the bovine lens capsules and from the human placenta were 20.1 +/- 7.7 nm (mode = 18 nm), 21.6 +/- 11.3 nm (mode = 14 nm), and 21.6 +/- 9.0 nm (mode = 18 nm), respectively. These observations suggest that collagen IV can, in the absence of other macromolecules including laminins, comprise a skeletal meshwork similar in dimensions to that of the lamina densa.

Animals↗
PubMed1997

[Effect of tea extracts, catechin and caffeine against type-I allergic reaction].

The antiallergic effects of green tea, oolong tea, and black tea extracts by hot water were examined. These extracts inhibited the passive cutaneous anaphylaxis (PCA) reaction of rat after oral administration. Three tea catechins, (--)-epigallocatechin (EGC), (--)-epicatechin gallate (ECg), and (--)-epigallocatechin gallate (EGCg) isolated from green tea showed stronger inhibitory effects than that of a green tea extract on the PCA reaction. The inhibitory effects of EGC and EGCg on the PCA reaction were greater than that of ECg. Caffeine also showed a inhibitory effect on the PCA reaction. These results indicate that tea could provide a significant protection against the type-I allergic reaction. These findings also suggest that tea catechins and caffeine play an important role in having an inhibitory effect on the type-I allergic reaction.

Administration, Oral↗
PubMed1997

Safety and efficacy of oral flecainide acetate in patients with cardiac arrhythmias.

We retrospectively studied the clinical efficacy and safety of oral flecainide in 38 patients with symptomatic arrhythmias. Patients received 100 to 200 mg daily of flecainide for a mean of 25 months (range 8 to 50 months). All patients had normal cardiac function. Paroxysmal atrial fibrillation (PAF) was observed in 29 patients (76%). Other forms of arrhythmia included paroxysmal atrial flutter, seen in 3 patients (8%); premature atrial contraction and ventricular premature contraction, each seen in 2 patients (5%); and supraventricular tachycardia and ventricular tachycardia, each seen in 1 patient (3%). A complete response was obtained in 15 (52%) of 29 patients with PAF and a partial response in 8 patients (27%). The remaining 6 patients (21%) showed no response. A complete response was also obtained in 7 of 9 patients with other forms of arrhythmia. There were no differences in cardiac function and ECG parameters before and after treatment. Flecainide was withdrawn in 4 patients due to the development of electrocardiographic abnormalities. Three of these patients showed an atrial proarrhythmic effect. Abnormal ST elevations in the precordial leads were observed in 1 patient who received 200 mg of flecainide daily. In conclusion, flecainide was effective treatment for supraventricular and ventricular arrhythmias, but attention must be paid to the drug's potential proarrhythmic adverse effects.

Administration, Oral↗
PubMed1996

Generation of novel killer hybridomas derived from proliferation-suppressed somatic cell hybrids between YACUT T cell lymphoma and normal lymphocytes activated in secondary mixed lymphocyte cultures.

Somatic cell hybridization between the YACUT T cell lymphoma cell line with normal lymphocytes activated in secondary mixed lymphocyte cultures (MLCs) consistently yielded IL-2-dependent CD4- CD8 alpha+ beta- Fc gamma RIII+ hybrids with cytotoxic function. The hybrids expressed T cell receptors other than that of YACUT origin, and fusion of the YACUT with a CD8 alpha+ beta+ Fc gamma RIII- T cell line also yielded hybrids with an unexpected CD8 alpha+ beta- Fc gamma RIII+ phenotype, which two observations strongly suggested that CD8+ T cells became the parental cell of the hybrids. Prolonged growth of the hybrids with IL-2 resulted in the generation of autonomously growing hybrids (hybridomas) without abrogating the cytotoxic function. The hybridomas exhibited MHC-unrestricted cytotoxicity in a Ca(2+)-dependent manner without prior stimulation and also mediated antibody-dependent cellular cytotoxicity. These results indicate that novel killer hybridomas can be produced following cell transformation of proliferation-suppressed cytotoxic YACUT x MLC cell hybrids. The killer hybridomas may be of value for analyzing recognition mechanisms and molecules involved in MHC-unrestricted cell-mediated cytotoxicity.

Animals↗
PubMed1996

Two-dimensional crystallization and cryo-electron microscopy of photosystem II.

Two dimensional (2D) crystals of photosystem II (PSII) were obtained from n-heptyl-beta-D-thioglucoside-solubilized monomers of spinach PSII complex by conventional detergent dialysis. The 2D crystals were either large cylindrical vesicles (1 to 2 micrometer by 4 to 6 micrometer as flattened vesicles) or large monolayer sheets (ca. 1 micrometer X 1 micrometer), both suitable for cryo-electron microscopy. Images of unstained crystals embedded in ice were recorded using low-dose microscopy and analyzed by digital image processing. Both types of crystals had the same unit cell size and the same packing arrangement of PSII particles. The plane group was p22(1)2(1) and the unit cell was rectangular with dimensions of 16.7 nm X 15.3 nm containing four monomers (two face-up and two face-down). SDS-PAGE and immunoblot analyses of the 2D crystal indicated that the constituent subunits of particles in the 2D were CP47, D1, D2, cytochrome b-559 and psbI protein. A projection map of 20 A resolution revealed that each monomer has asymmetrical shape with a length of 8.1 nm and a maximal width of 7.5 nm consisting of four areas of density. Two high-density areas with similar sizes were located close to each other to form a roughly rectangular core of 4.0 nm X 6.5 nm. From its size similarity to the size of the L/M heterodimer of the bacterial reaction center, this high density core area was tentatively assigned to the D1/D2 heterodimer. The remaining large and small areas were also tentatively assigned to CP47 and cytochrome b-559 plus psbI protein respectively.

Crystallization↗
PubMed1996

Deregulated c-myc expression is insufficient for emergence of the tumorigenic phenotype in malignancy-suppressed intratypic T-cell lymphoma hybrids: an in vitro model for multistep lymphomagenesis.

The T-cell lymphoma cell line YACUT was fused with the Mls-1a antigen-responsive non-tumorigenic T-cell line G4 to construct growth-arrested hybrids which could be induced to proliferate in the presence of Mls-1a antigen. Prolonged growth of the hybrids by repeated antigenic stimulation resulted in the emergence of cells with transformed phenotype, which was accompanied by a reversion of c-myc expression to the levels of the YACUT lymphoma parent and an increase in the number of YACUT-derived chromosome 15 carrying the rearranged pvt-1 gene. Despite these two changes, early passage transformed hybrids as well as proliferation-suppressed hybrids were non-tumorigenic in vivo. The fact that only late passage transformed hybrids produced tumors in vivo indicated that additional genetic and/or epigenetic alterations are required for the emergence of hybrid lines with tumorigenic phenotype. Thus, this experimental system offers tangible possibilities for delineation of the three distinct phenotypes which could be exploited for the investigation of the multistep process of lymphomagenesis.

Animals↗
PubMed1996

Gel formation from the type IV collagen isolated from bovine lens capsule in guanidine-HCl and dithiothreitol.

Type IV collagen was prepared from bovine lens capsule by acetic acid extraction, followed by purification including DEAE-Sephacel chromatography and dialysis. The type IV collagen solution became viscous and eventually gelated upon dialysis against 2M guanidine-HCl and 10 mM dithiothreitol. Gelation was not observed for heat-denatured type IV collagen, suggesting that collagenous conformation may be required for the gelation. A reducing agent, dithiothreitol, was essential for the gelation of type IV collagen in 2 M guanidine-HCl. An optimal concentration of guanidine-HCl for the gelation lays between 1.5 and 2.5 M: gelation did not occur at 1 M or lower and at 3 M or higher, although the circular dichroism spectrum characteristic of the collagenous triple-helix was not changed in 3 M guanidine-HCl. This suggests that an appropriate change in conformation of the type IV collagen at a region other than the triple-helical region or/and partial dissociation of complexed type IV collagen aggregates may drive intermolecular interactions of the type IV collagen leading to polymerization and eventually to gelation. To our knowledge, this is the first report that the type IV collagen alone has the ability to form a rigid gel. The assembled structure of the type IV collagen in gel form might be related to the skeletal architecture of basement membrane(s).

Animals↗
PubMed1996

Gelation of the lens capsule type IV collagen solution at a neutral pH.

It is known that the type IV collagen extracted from EHS tumor assembles under a physiological condition, but not in a gel form. The EHS type IV collagen requires the other basement membrane components, laminin1, heparansulfate proteoglycan, and/or nidogen for gelation. On the other hand, Muraoka et al. reported that the bovine lens capsule type IV collagen alone gelated under a unique and unexpected condition of 2 M guanidine-HCl and 50 mM dithiothreitol, a condition which is thought to be dissociative for most biological macromolecules, including extracellular matrix [Muraoka, M. et al. (1996) J. Biochem. 119, 167-172]. The present report shows that the bovine lens capsule type IV collagen formed a gel under physiological conditions of pH and ionic environment, though the apparent rigidity of the gel was weaker than that of the gel formed in 2 M guanidine-HCl and dithiothreitol. The rigidity depended greatly on the incubation temperature and NaCl concentration of the type IV collagen solution, as observed in terms of the contractility of gel volume under centrifugal force. the gel formed in 150 mM NaCl and 20 mM phosphate, pH 7.3, at 28 degrees C contracted to 20% of the original volume on centrifugation of 1,800 x g for 10 min, while the gel formed at 4 degrees C, where type I collagen did not gelate at all, retained 90% of the original volume at the same centrifugal force. NaCl concentration was another important factor influencing the mechanical properties of type IV collagen gel. The gel formed at 150 mM showed maximal rigidity in the range of 0 to 300 mM in terms of the contractility on centrifugation. An image of a Pt/C replica of the gelated type IV collagen reconstituted at 4 or 28 degrees C in 20 mM phosphate, pH 7.3, containing 150 mM NaCl showed fine meshworks consisting of rather homogeneous pore sizes, resembling the skeletal structure of basal lamina. Since the condition where the type IV collagen alone formed gels was physiological in terms of ionic strength and pH, the aggregate structure and gel properties might reflect the in vivo type IV collagen supramolecular structure and the property.

Animals↗
PubMed1996

Idiopathic ventricular fibrillation initiated by a short-coupled ventricular premature beat.

We report the case of a 38-year-old man who had idiopathic ventricular fibrillation (VF) which initiated by abnormally short-coupled ventricular premature beats. VF was successfully prevented by the combination of pilsicainide, propranolol, and verapamil. In particular, the effects of pilsicainide are assumed to exert an important effect in controlling this arrhythmia. Class Ic drugs may be effective for preventing VF initiated by short-coupled VPBs.

Adult↗
PubMed1996

Personality, longevity, and successful aging among Tokyo metropolitan centenarians.

The purpose of our study was to examine two hypotheses: 1) that androgyny and Type B behavior are related to longevity; and 2) that personality characteristics associated with longevity may also be related to successful aging. Participants were eighty-two centenarians (37 men and 45 women) who were compared with 605 elderly in their sixties, seventies, and eighties. Both groups were living in the Tokyo metropolitan area. We used the Bem Sex Role Inventory and Bortner Pattern A Behavior Scales to measure personality, and the Rosenberg Self-Esteem Scale and Cattell Anxiety Scale to measure successful aging. We found that androgyny was not more prominent among centenarians than masculinity, femininity, or undifferentiated. In fact, more femininity was observed. Additionally, we found that more women were classified as feminine than were men. The results indicated more Type B's among centenarians than among those in their sixties and more women than men showed Type B behavior. Our hypothesis that Type B behavior is related to longevity was supported. We observed lower self-esteem for femininity than for either the masculinity or androgyny. We also observed that anxiety was lower for femininity than masculinity but higher than androgyny among women. Type B women showed lower self-esteem than Type A women. Type B men showed lower anxiety than Type A men. We conclude that femininity is related to longevity and that androgyny may be related to successful aging. Further, we suggest that Type B behavior is associated with longevity, but its relationship to successful aging differs between men and women.

Aged↗
PubMed1996

Effects of granulocyte-macrophage colony-stimulating factor on the levels of VLDL and LDL receptor mRNAs in vivo.

We investigated the mechanism by which granulocyte-macrophage colony-stimulating factor (GM-CSF) lowers plasma cholesterol levels. Recombinant human GM-CSF (rhGM-CSF) was administered to normal and Watanabe heritable hyperlipidemic (WHHL) rabbits. Treatment with rhGM-CSF reduced the levels of cholesterol and triglyceride in these animals. In vitro colony assay for hematopoietic progenitors indicated that rhGM-CSF was capable of supporting granulocyte-macrophage colony formation in rabbits, suggesting that rhGM-CSF stimulates macrophage function even in rabbits. Northern blot analysis of rabbit very-low density lipoprotein (VLDL) receptor showed that rhGM-CSF elevated the levels of VLDL receptor mRNA 2.6- and 1.8-fold in muscles of normal WHHL rabbits, respectively, 1.5 hours after a single injection. Increases of 1.5- and 1.4-fold were observed in muscles of these rabbits after 5 days of administration. No changes were found in the LDL receptor mRNA levels in liver, spleen or bone marrow. These findings show that the lowering of lipids by GM-CSF may be mediated through the up-regulation of the VLDL receptor mRNA and the enhancement of macrophage function.

Animals↗
PubMed1996

Expression of very low density lipoprotein receptor mRNA in rabbit atherosclerotic lesions.

The expression of very low density lipoprotein (VLDL) receptor mRNA in atherosclerotic lesions in rabbits was investigated. To examine the expression of the VLDL receptor in the vascular wall, poly(A)+ RNA was isolated from whole aortas of cholesterol-fed New Zealand White (NZW), Watanabe heritable hyperlipidemic (WHHL), and normal NZW rabbits, and then Northern blot analysis was performed. The VLDL receptor mRNA was detected in aortas from both NZW rabbits fed 0.5% cholesterol for 16 weeks and 12-month-old WHHL rabbits, whereas no expression was seen in normal NZW rabbit aortas. To further determine the localization of the VLDL receptor mRNA, in situ hybridization using digoxigenin-labeled riboprobes and immunohistochemistry using monoclonal antibodies against each cell component were performed. Early atherosclerotic lesions, termed fatty streaks, in the NZW rabbits fed 0.5% cholesterol for 4 weeks demonstrated strong expression of the VLDL receptor mRNA by macrophages. The VLDL receptor mRNA was also expressed in more advanced atherosclerotic lesions from both atherogenic animal models. The predominant origin of the VLDL receptor mRNA-positive cells was macrophages, and some intimal smooth muscle cells appeared to express a weak but significant signal in these advanced lesions. Our findings suggest that the VLDL receptor expression may play a role in the development of atherosclerosis.

Animals↗
PubMed1995

Isolation and characterization of a Photosystem II complex from the red alga Cyanidium caldarium: association of cytochrome c-550 and a 12 kDa protein with the complex.

A Photosystem II (PS II) complex was purified from an acidophilic as well as a thermophilic red alga, Cyanidium caldarium. The purified PS II complex was essentially devoid of phycobiliproteins and other contaminating components, and showed a high oxygen-evolving activity of 2375 mumol O2/mg Chl per h using phenyl-p-benzoquinone as the electron acceptor. The expression of this high activity did not require addition of exogenous Ca2+, although EDTA reduced the activity by 40%. This effect of EDTA can be reversed not only by Ca2+ but also by Mg2+; a similar Mg2+ effect has been observed in purified cyanobacterial PS II but not in higher plant PS II. Immunoblotting analysis indicated the presence of major intrinsic polypeptides commonly found in PS II from cyanobacteria and higher plants as well as the extrinsic 33 kDa protein. Antibodies against the extrinsic 23 and 17 kDa proteins of higher plant PS II, however, did not crossreact with any polypeptides in the purified PS II, indicating the absence of these proteins in the red alga. In contrast, two other extrinsic proteins of 17 and 12 kDa were present in the red algal PS II; they were released by 1 M Tris or Urea/NaCl treatment but not by 1 M NaCl. The 17 kDa polypeptide was identified to be cytochrome c-550 from heme-staining, immunoblot analysis and N-terminal amino acid sequencing, and the 12 kDa protein was found to be homologous to the 12 kDa extrinsic protein of cyanobacterial PS II from its N-terminal sequence. These results indicate that PS II from the red alga is closely related to PS II from cyanobacteria rather than to that from higher plants, and that the replacement of PS II extrinsic cytochrome c-550 and the 12 kDa protein by the extrinsic 23 and 17 kDa proteins occurred during evolution from red algae to green algae and higher plants.

Amino Acid Sequence↗
PubMed1994

Continuous beds for microchromatography: cation-exchange chromatography.

Microcolumns (i.d. 10-320 microns) for cation-exchange chromatography can be prepared simply by polymerization of an aqueous solution of appropriate monomers, including the desired ligand, directly in the chromatographic tube (fused-silica tubing) in the presence of salt. The beds thus prepared are in the form of rods traversed by channels through which the eluent can pass. The walls of the channels are composed of very small particles and are impermeable to peptides and proteins, which is important for rapid mass transfer and thus for high resolution at high flow rates. The bed becomes attached covalently to the tube wall during synthesis. A complicated column tube design with a supporting frit at the bottom is thus eliminated. The absence of a frit reduces the flow resistance and facilitates interfacing to mass spectrometers. The covalent linkage of the bed to the tube wall also serves to suppress the zone-broadening "wall effect." A homogeneous "packing" of a continuous bed column with an inner diameter as small as 10 microns is easily obtained. The resolution, binding capacity, and flow rate (i.e., run time at a given pressure) can be varied by changing the composition of the monomer solution. One can thus tailor the beds to each separation problem. The chromatographic properties of the microcolumns are demonstrated by separations of model proteins.

Chromatography, Ion Exchange↗