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Biomedical subjects

K Naito

Publications and source records attributed to K Naito.

At least 91 records · Page 5Linked to original sources
PubMed2000

Reduction of intramembranous particles in the periacrosomal plasma membrane of boar spermatozoa during in vitro capacitation: a statistical study.

Membrane remodeling in the periacrosomal plasma membrane (PAPM) of boar spermatozoa during incubation in capacitation medium was examined by the freeze-fracture technique. In the preservation medium (PM) group, the major small (about 8 nm) intramembranous particles (IMP) and the minor large (> 10 nm) IMP were distributed evenly in the PAPM. The IMP-free area increased during capacitation. To correct the IMP-free area, arithmetically redistributed (ARD)-IMP density was used for statistical analysis. In the PM group, the mean density +/- SD of large IMP was 379 +/- 64 and 266 +/- 58/microm2, and that of small IMP was 1450 +/- 155 and 672 +/- 252/microm2 in protoplasmic (P) and external (E) faces, respectively. During capacitation, the significant (P < 0.01) reduction of large IMP density was encountered only in the E face of a few incubation groups, while that of the small IMP density occurred in the P face by 2 h. Consequently, reduction of the total IMP density of both faces was not significant in the large IMP, but it was significant (P < 0.01) in the small IMP. One-fifth of the total small IMP density reduced by 2 h. Filipin-sterol complexes (FSC) were numerous in the PAPM, and FSC-free areas also increased during capacitation. The mechanism of IMP-free area formation and the behavior of the small IMP in the PAPM during capacitation were discussed in relation to membrane stability.

Acrosome↗
PubMed2000

Declining of memory functions of normal elderly persons.

Two studies examined the declining of memory functions in normal elderly persons using the Yokota memory test (YMT), which includes 15 items concerning verbal and non-verbal memory functions. In the first study, 552 subjects over 40 years of age in five age groups were examined. Factor analysis revealed that YMT consisted of two factors pertaining to short-term/working memory, and two factors pertaining to long-term memory. It is suggested that the former was more affected than the latter, with aging. In the second study, YMT was examined in relation to the revised version of Hasegawa dementia scale (HDS-R), which was the most popular intelligence scale for the elderly in Japan. As a result, memory functions differentially declined with the decreasing score of HDS-R, which suggests that memory functions differentially declined with progressive risk of dementia.

Adult↗
PubMed2000

Diagnostic value of prostate-specific antigen-related parameters in discriminating prostate cancer.

BACKGROUND: Using the percentage (of total) of free prostate-specific antigen (PSA) in discriminating prostate cancer (CaP) from benign prostate hyperplasia (BPH) has not been fully delineated in Japanese men. To clarify the clinical significance of percent free PSA, various parameters, including total prostate volume, percent free PSA, PSA density (PSAD) and PSA density of transition zone volume (PSAT), were compared. METHODS: Ninety-seven patients who had visited one of three community-based hospitals, and whose total PSA value ranged from 4 to 20 ng/mL were prospectively enrolled in this study. Fresh sera were applied to measure the percent free PSA. RESULTS: Of the 97 patients, CaP and BPH were diagnosed in 24 (25%) and 73 patients, respectively. In discriminating CaP patients, the cutoff values of 17% for percent free PSA, 0.3 ng/mL per cm3 for PSAT, and 0.19 ng/mL per cm3 for PSAD yielded specificity levels of 56, 40 and 58% at sensitivity levels of 92, 92 and 79%, respectively. As for the 65 patients with intermediate PSA, range 410 ng/mL, and normal digital rectal examination, the percent free PSA and total prostate volume statistically discriminated CaP patients from BPH patients. A multiple logistic regression model proved percent free PSA to be the only significant discriminating factor (P=0.045; odds ratio, 9.06). CONCLUSIONS: This prospective study revealed percent free PSA to be a significant useful predictor in discriminating CaP from BPH in Japanese men.

Aged↗
PubMed2000

Phosphorylation of mitogen-activated protein kinase cascade during early embryo development in the mouse.

The mitogen-activated protein kinase (MAPK) cascade is one of the most important signal transduction pathways that regulate the cell cycle in somatic cells. The present study examined the phosphorylation states of components in the MAPK cascade, Raf-1, MEK-1, and extracellular signal regulated kinases (ERKs), which are activated by mitogens, throughout early mouse embryo development and in cultured somatic cells generally. In somatic cells, Raf-1 and MEK-1 were phosphorylated at M-phase and dephosphorylated during interphase. ERKs were not phosphorylated at any stage during the cell cycle. These results were similar to previous findings for the first and second cell cycles of early mouse embryos. In contrast, after the four-cell stage, not only ERKs, but also Raf-1 and MEK-1, were not phosphorylated at any stage during the cell cycle in mouse early embryos. These results suggest that the MAPK cascade in mouse embryos is regulated by the same mechanism as in somatic cells before the two-cell stage, and that regulation is changed to an embryo-specific mechanism after the four-cell stage.

3T3 Cells↗
PubMed2000

Maturation/M-phase promoting factor: a regulator of aging in porcine oocytes.

Deterioration in the quality of mammalian oocytes during the metaphase-II arrest period is well known as "oocyte aging." Oocytes in which aging has occurred are called aged oocytes, and these oocytes show enhanced activation and higher fragmentation rates after parthenogenetic activation. Previously we showed that porcine aged oocytes had low maturation/M-phase promoting factor (MPF) activity, and we suggested that this low MPF activity contributed at least in part to the aging phenomena. In the present study, we examined the relationship between MPF activity and these aging phenomena by artificially regulating MPF activity in porcine metaphase-II-arrested oocytes. Since we have shown recently that aged porcine oocytes contain abundant phosphorylated inactive MPF, so-called pre-MPF, we used vanadate and caffeine, which affect the phosphorylation status of MPF, to regulate MPF activity. Incubation of 48-h-matured oocytes with vanadate for 1 h increased the phosphorylation of MPF and decreased MPF activity. The parthenogenetic activation and fragmentation rates were significantly increased compared with those of control oocytes. Conversely, treatment of 72-h-cultured aged oocytes with caffeine (last 10 h of culture) decreased the level of pre-MPF and elevated MPF activity. These oocytes revealed significantly lower parthenogenetic activation rates and a lower percentage of fragmentation than did untreated aged oocytes. These results indicate that not only the increased ability for parthenogenetic activation but also the increased fragmentation rate observed in porcine aged oocytes may be attributable in part to the gradual decrease in MPF activity during prolonged culture. Control of MPF phosphorylation with these agents may allow for some degree of manipulation of oocyte aging.

Animals↗
PubMed2000

Inhibition of calpain but not caspase protects the testis against injury after experimental testicular torsion of rat.

Testicular torsion requires emergent release of the twisted spermatic cord. Ischemia/reperfusion (I/R) plays an important role in its pathogenesis, and recent data suggest that germ cells undergo apoptosis during I/R. In a model of torsion/detorsion (i.e., I/R) of the rat testis, involvement of calpain and caspase in necrotic and apoptotic cell death was examined. After 1 h of ischemia followed by 0, 0.5, 1, 6, or 24 h of reperfusion, the germ cells positively stained with in situ TUNEL, and DNA fragmentation, activation of caspase-3, and proteolysis of caspase substrates increased with time of reperfusion, demonstrating apoptosis. In addition, m-calpain activation and proteolysis of alpha-fodrin were increased during reperfusion, and its activation is thought to be involved in the necrosis. A calpain inhibitor, acety-leucyl-leucyl-norleucinal, inhibited the phenomena associated with apoptosis and necrosis induced by I/R, although a caspase inhibitor, Z-Val-Ala-Asp-fluoromethlyketone, only inhibited apoptotic changes. The inhibition of calpain but not caspase ameliorated the injury after 60 days of reperfusion following 1 h of ischemia. The calpain inhibitor injected just before reperfusion effectively suppressed alpha-fodrin proteolysis, suggesting its usefulness in the treatment of testicular torsion.

Animals↗
PubMed2000

Spicamycin and KRN5500 induce apoptosis in myeloid and lymphoid cell lines with down-regulation of bcl-2 expression and modulation of promyelocytic leukemia protein.

Spicamycin is a potent inducer of differentiation of human myeloid leukemia cells (HL-60) and murine myeloid leukemia cells (M1). One of the spicamycin derivatives, KRN5500, shows a broad spectrum of antitumor activity against human tumor xenografts in nude mice. In this study, we first investigated the differentiation efficacy of spicamycin and KRN5500 in HL-60 and acute promyelocytic leukemia cell line, NB4, and found that low concentrations of both compounds induced differentiation to a small extent in both cell lines, but markedly induced apoptosis in NB4 cells. Further investigation in a myeloid leukemia cell line, NKM-1, a lymphoma cell line, Daudi, and a multiple myeloma cell line, NOP-1, showed that high concentrations of both compounds also induced apoptosis in these cells. The 50% inhibitory concentration (IC(50)) determined by 3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that myeloid cells were more sensitive to both compounds than lymphoid cells, and spicamycin was more potent than KRN5500. Western blot analysis of Bcl-2, Bcl-xL and Bax expression and immunofluorescence analysis of promyelocytic leukemia (PML) protein indicated that apoptosis induced by spicamycin and KRN5500 was associated with down-regulation of Bcl-2 expression and modulation of PML protein. Thus, spicamycin and KRN5500 may be useful for the treatment of myeloid and lymphoid neoplasms.

Antibiotics, Antineoplastic↗
PubMed2000

Pharmacological profile of VP-343, a novel selective vasopressin V2 receptor antagonist, in rats.

The pharmacological profile of a novel selective vasopressin V2 receptor antagonist, VP-343(N-[4-[[(2S,3aR)-2-hydroxy-2,3,3a,4-tetrahydropyrrolo[ 1,2-a]quinoxalin-5(1H)-yl]carbonyl]phenyl]-4'-methyl[1,1'-biphenyl ]-2-carboxamide) was characterized in several in vitro and in vivo rat models. The IC50 values of VP-343 for vasopressin V1A and V2 receptors were 110 and 0.77 nM, respectively. VP-343 inhibited dose-dependently the pressor response to exogenous arginine vasopressin (AVP; 30 mU/kg, i.v.) in pithed rats, with an ID50 value of 0.57 mg/kg (i.v.). VP-343 induced strong aquaresis in normal saline-loaded conscious rats. Antidiuretic activities of VP-343 have not been detected in AVP deficient Brattleboro rats, showing its lack AVP V2 agonistic activity. During repeated administration for 21 d (3 mg/kg, p.o.) and after recovery, the aquaretic action of VP-343 still remained. In the aged (17 month) saline-loaded conscious rats study, VP-343 (3 mg/kg, p.o.) exhibited remarkable diuretic action. In a single dose oral toxicity study in mice, VP-343 did not produce any clinical signs and mortality at any of the tested doses. The results indicate that VP-343 is a potent, orally active, selective V2 receptor antagonist, suggesting that it can be expected to be useful as an aquaretic drug.

Animals↗
PubMed2000

Microbial contamination of in-use lubricants for non-touch urethral catheters in intermittent self-catheterization.

There are no reports on microbial contamination of repeatedly used lubricant (84-87% glycerin containing 0.02% benzalkonium chloride) for non-touch urethral catheters in intermittent self-catheterization. In this work, we evaluated microbial contamination of in-use lubricant and its prevention. Between September and December, 1996, microbial contamination and water activity of in-use lubricants in sheathed and lubricated non-touch catheters connected to a tube used by 46 outpatients at our hospital was examined. Microbial contamination was detected at 5 to 2.6 x 10(8) colony-forming units (CFU)/ml in 14 (30.4%) of 46 samples. With higher water activity of the lubricant (a higher dilution rate of the lubricant with water), a higher concentration of microbial contamination was observed. In 3 (21.4%) of the 14 patients using contaminated lubricant, urine samples showed the same microbial species as those detected in the lubricant. To prevent microbial contamination of the lubricant, dilution of the lubricant with water, as a result of repeated use, should be avoided.

Bacteria↗
PubMed2000

[Pharmacological profiles of the potent carbonic anhydrase inhibitor dorzolamide hydrochloride, a topical antiglaucoma agent].

Carbonic anhydrase (CA) plays an important role in the secretion of aqueous humor. The orally administered CA inhibitor acetazolamide lowers the intraocular pressure (IOP) of patients with glaucoma. However, approximately 50% of patients stop treatment with acetazolamide as a consequence of intolerable side effects due to the extraocular inhibition of the enzyme. This prompted attempts to develop a topically active CA inhibitor. Merck Research Laboratories focused on developing a water- and solvent-soluble compound to penetrate the cornea. Dorzolamide hydrochloride is a potent inhibitor of human CA isoenzyme II, with an IC50 value of 0.18 nM in vitro. In contrast, its inhibitory activity against human CA isozyme I is much weaker (IC50 value of 600 nM). Topically administered dorzolamide penetrated the ciliary body, inhibited its CA activity and had a hypotensive effect in rabbits; in contrast, topical administration of acetazolamide or methazolamide did not decrease IOP. In clinical trials, dorzolamide administered 3 times daily was effective in lowering IOP in patients with open-angle glaucoma or ocular hypertension. The hypotensive effect of dorzolamide 0.5% was similar to that of oral CA inhibitors or timolol (0.25%) twice daily. Dorzolamide did not induce the severe systemic adverse events associated with oral CA inhibitors. Dorzolamide was as effective as pilocarpine or dipivefrine as an adjunctive therapy in patients receiving beta-adrenergic antagonists. Dorzolamide also reduced IOP and accelerated retinal arteriovenous passage time in addition to improving visual function in patients with normal-tension glaucoma.

Animals↗
PubMed2000

Identification of skeletal muscle satellite cells by transfecting EGFP driven by skeletal alpha-actin promoter.

In isolating skeletal muscle satellite cells, sometimes a problem is encountered in removing contaminating nonmyogenic cells. In the present study, we constructed a novel vector, pSKA-EGFP, which achieves the expression of enhanced green fluorescent protein (EGFP) exclusively in myogenic cells under the control of skeletal alpha-actin promoter when transfected to primary cultured cells from skeletal muscle. Cells from rat skeletal muscle positive for EGFP after transfecting with pSKA-EGFP were all positive for desmin and none of the nonmyogenic cells expressed EGFP, indicating that the expression of EGFP is specific to myogenic cells. Among the cells positive for EGFP were proliferating cells, presumably satellite cells. In addition, EGFP positive cells derived from horse skeletal muscle after transfecting pSKA-EGFP in vitro formed multinuclear myotubes, indicating that myogenic expression of EGFP driven by skeletal alpha-actin was achieved also in the equine cells. These results indicated that pSKA-EGFP vector will be useful in identifying and following up the satellite cells in real time, and also permit us to isolate satellite cells in combination with fluorescence-activated cell sorting (FACS).

Actins↗
PubMed2000

[A case of synchronous cervical lymph node metastases from testicular and thyroid cancers showing mixed response to chemotherapy].

We report a case of synchronous presentation of thyroid cancer and testicular seminoma with lymph node metastasis. A 37-year-old man presented with right scrotal swelling and multiple lymph node swelling. We performed right radical orchiectomy, and histological examination revealed a seminoma of the testis. After systemic work-up for staging, we diagnosed the patient with multiple lymph node metastasis of the seminoma, and administered three cycles of bleomycin, etoposide, and cisplatin (BEP) therapy. Although the chemotherapy was very effective for the retroperitoneal and left cervical lymph node metastases, the right cervical tumor did not change. Retroperitoneal lymphadenectomy combined with right cervical lymph node dissection and hemi-thyroidectomy were performed on September 8, 1998. Pathological examination of the thyroid revealed papillary thyroid cancer and its right cervical lymph node metastasis. There was no evidence of viable cancer cells from either of the primary cancers in the retroperitoneal lymph node. Unresponsiveness to chemotherapy for metastatic lesions from testicular cancer might be a useful clue to detect primary tumors of other origins.

Adult↗
PubMed2000

[A case of Kallmann syndrome: diagnostic usefulness of cranial magnetic resonance imaging].

We report a case of Kallmann syndrome in which the cranial magnetic resonance imaging (MRI) findings of the olfactory tract were useful in making the diagnosis. A 20-year-old male who complained of delayed puberty was referred to our hospital in November 1998. He presented with hypogonadism and anosmia. The plasma levels of testosterone, luteinizing hormone (LH) and follicle stimulating hormone (FSH) were low. Pituitary and Leydig cell functions were normal by the LH-releasing hormone test and human chorionic gonadotropin (hCG) loading test, respectively. The karyotype was normal (46, XY). The smell test showed anosmia. After administration of hCG, a good response of plasma testosterone level and masculinization were recognized. Cranial MRI findings revealed an absence of olfactory bulbs and hypoplastic olfactory sulci. These MRI findings are characteristic of Kallmann syndrome and allowed us to confirm our diagnosis, in addition to classically used endocrinological and olfactory examination.

Adult↗
PubMed2000

Experimental use of a compact centrifugal pump and membrane oxygenator as a cardiopulmonary support system.

Compactness and high performance are the most important requirements for a cardiopulmonary support system. The Nikkiso (HPM-15) centrifugal pump is the smallest (priming volume; 25 ml, impeller diameter; 50 mm) in clinically available centrifugal pumps. The Kuraray Menox (AL-2000) membrane oxygenator, made of double-layer polyolefin hollow fiber, has a minimum priming volume (80 ml) and a low pressure loss (65 mm Hg at 2.0 L/min of blood flow) compared with other oxygenators. The aim of this study was to evaluate the performance of the most compact cardiopulmonary support system (total priming volume: 125 ml) in animal experiments. The cardiopulmonary bypass was constructed in a canine model with the Nikkiso pump and Menox oxygenator in comparison with a conventional cardiopulmonary support system. The partial cardiopulmonary bypass was performed for 4 h to evaluate the gas exchange ability, blood trauma, serum leakage, hemodynamics, and blood coagulative parameters. The postoperative plasma free hemoglobin level of the compact cardiopulmonary system was 29.5 +/- 10.21 mg/dl (mean +/- SD), which was lower than that of the conventional cardiopulmonary system, 48.75 +/- 27.39 mg/dl (mean +/- SD). This compact cardiopulmonary system provided the advantage in terms of reduction of the priming volume and less blood damage. These results suggested the possibility of miniaturization for the cardiopulmonary bypass support system in open-heart surgery in the near future.

Animals↗
PubMed2000

Management of suspected nosocomial infection: an audit of 19 hospitalized patients with septicemia caused by Bacillus species.

From April to August of 2000, Bacillus spp. were detected in the blood culture of 29 patients in a hospital in Japan. Of these patients, 19 had clinical signs of septicemia; positive culture in the remaining 10 patients was attributed to contamination with skin flora at the site of puncture. Of the 18 strains evaluated, 15 were Bacillus cereus, 2 were Bacillus subtilis, and one was Bacillus licheniformis. The only hospital death observed was that of a patient who had no clinical signs of septicemia at the time of blood sampling. That death is now considered attributable to the underlying neoplasm. The hospital committee for prevention of nosocomial infection concluded after a critical review of the patient records that the cause of septicemia in most cases had been contaminated intravenous lines. To control the situation, the committee recommended the use of a new skin disinfectant, and medical personnel were advised to avoid infusion pauses with interruption of intravenous lines and to replace the caps for the stopcocks with new ones each time the caps were removed. These measures were rigorously observed in addition to the conventional measures for preventing catheter sepsis, and the incidence of septicemia due to the Bacillus spp. declined dramatically thereafter.

Adult↗
PubMed2000

[An electron microscopic study of the relation between epithelial cell damage and eosinophilia in the nasal mucosa of patients with nasal allergy].

To determine the relationship between epithelial damage and eosinophilia in the nasal mucosa of patients with nasal allergy, we examined the nasal mucosa (obtained by surgery) from 74 patients with allergic rhinitis, using light and electron microscopy. The extent of eosinophilia correlated significantly to grades of epithelial damage and torn tight junctions of the epithelial cells. No significant relationships were found between the severity of nasal symptoms and the extents of eosinophilia or grades of torn tight junctions of the epithelial cells. More than 50% specific granules in eosinophils in the allergic nasal mucosa showed normal findings. There were no significant relationships between the extent of eosinophil degranulation and grades of epithelial damage. Based on our results, the release of tubular vesicular structures from the eosinophil granule may be one form of eosinophil degranulation in the nasal mucosa of patients with nasal allergy.

Adult↗
PubMed1999

Toluene inhalation induced epididymal sperm dysfunction in rats.

Toluene is a widely abused inhaled solvent. This study was designed to determine whether toluene abuse affects the reproductive functions or general health of males. Seven-week-old male Sprague-Dawley rats were exposed to toluene vapor inhalation (0, 4000, or 6000 ppm; 2 h/day) daily for 5 weeks. Exposure-related suppression of body weight gain and food consumption were observed. Salivation and lacrimation were observed during exposure periods and intensified with repeated exposure. Rats exposed to 6000 ppm toluene had decreased spleen and thymus weights, as well as suppressed lymphocyte counts. In 6000 ppm group, the epididymal sperm counts, sperm motility, sperm quality and in vitro penetrating ability to zona-free hamster eggs were significantly reduced, while no exposure-related changes in the testes weight or spermatogenesis within testes were detected. Tail-less sperm heads were seen within zona-free eggs incubated with sperm from rats exposed to 6000 ppm toluene, but not control rats. No significant changes were observed in serum luteinizing hormone, follicle-stimulating hormone, or testosterone levels following 1 month of exposure to 6000 ppm toluene. These results indicate that high concentrations of toluene may directly target sperm in the epididymis and disrupt sperm maturation.

Animals↗