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Biomedical subjects

M Sakai

Publications and source records attributed to M Sakai.

At least 91 records · Page 5Linked to original sources
PubMed2001

A case of canine primitive neuroectodermal tumor (PNET).

A 2-year and 6 month-old, female, Golden Retriever showed circling behavior and seizure. By magnetic resonance imaging (MRI) examination, a mass was found on the surface of the left cerebral hemisphere, invading to the left temporal muscle. The skull bone between them was destroyed. The dog was euthanized and necropsied. Histologically, the mass contained a lot of undifferentiated anaplastic cells, forming Homer-Wright rosettes and pseudopalisading patterns. Thus, the case was diagnosed as primitive neuroectodermal tumor (PNET).

Animals↗
PubMed2001

Primary sclerosing cholangitis complicated with idiopathic thrombocytopenic purpura.

We present a 66-year-old woman with primary sclerosing cholangitis (PSC) complicated with idiopathic thrombocytopenic purpura (ITP). Both PSC and ITP are considered to reflect an immunological disturbance. However, their coexistence is very rare and to the best of our knowledge this is only the second reported case. In Japan, PSC patients are rarely treated with liver transplantation. Fortunately, the present patient underwent successful hepatic transplantation from a brain-dead donor and simultaneous splenectomy. This case emphasizes the importance of liver transplantation as an effective treatment for primary sclerosing cholangitis.

Aged↗
PubMed2001

Calciphylaxis in a patient with end-stage renal disease secondary to systemic lupus erythematosus associated with acral gangrene and mesenteric ischemia.

A patient with end stage renal disease secondary to systemic lupus erythematosus (SLE) ultimately required amputation of the four extremities and developed mesenteric ischemia. The patient presented with widespread medial calcification involving various small to medium sized arteries, although no noticeable secondary hyperparathyroidism was observed. We speculated that SLE associated with systemic vasculitis and uremic milieu over a number of years may represent the perfect preexisting condition for calcific arteriolopathy to occur following which several factors including chronic administration of corticosteroids, photosensitivity in lupus, and significant weight loss may have contributed to acral gangrene and mesenteric ischemia.

Amputation, Surgical↗
PubMed2001

Novel macrolactins as antibiotic lactones from a marine bacterium.

Seven new macrolactins (named G~M) and known macrolactins A and F were isolated from a culture broth of Bacillus sp. PP19-H3. The strain had been isolated from the macroalga, Schizymenia dubyi. Macrolactin A, which was 24-membered lactone, had previously been reported to show antibacterial, cytotoxic and antiviral activities. The new macrolactins include 22-membered ring or dicyclic lactone in addition to geometric isomers of known macrolactins A and F. The antibacterial activities of all the macrolactins examined in this study were relatively weak.

Anti-Bacterial Agents↗
PubMed2001

Estrogen replacement therapy in postmenopausal women: a study of the efficacy of estriol and changes in plasma gonadotropin levels.

The purpose of this study was to clarify the efficacy of estriol for estrogen replacement therapy in postmenopausal women with undefined symptoms and to evaluate endocrinological changes during therapy in relation to clinical outcome. Administration of 2 mg estriol in 168 postmenopausal patients was markedly effective in 22.6% of cases, effective in 45.2%, fairly effective in 14.3%, and ineffective in 17.9% of cases. The plasma concentration of follicle-stimulating hormone (FSH) and luteinizing hormone (LH) after administration of estriol decreased significantly (p < 0.001), by 52.2% and 32.9%, respectively for markedly effective cases, and by 39.1% and 48.0% for effective cases. In contrast, the plasma estradiol concentration remained unchanged. On the other hand, decreases in FSH and LH concentration were 13.9% and 5.9% for the fairly effective and 8.2% and 1.9% for ineffective cases, demonstrating a significantly lower decrease in plasma FSH and LH levels than in the markedly effective and effective cases (p < 0.001). For cases showing side-effects, the plasma FSH and LH levels decreased by 52.0% and 64.3%, respectively, whereas the plasma estradiol level remained unchanged. In conclusion, the efficacy of estriol was significantly correlated to the degree of decrease in plasma FSH and LH levels in patients with undefined symptoms. In addition, efficacy appeared to be correlated to the incidence of side-effects. The degree of reduction of FSH (39.1-52.2%) and LH (48.0-64.3%) from the baseline may possibly be used as a guide to the therapeutic hormone levels during HRT. The present results suggest that plasma gonadotropin levels could be a useful indicator in the management of patients undergoing estrogen replacement therapy.

Biomarkers↗
PubMed2001

Effects of unkei-to, an herbal medicine, on endocrine function and ovulation in women with high basal levels of luteinizing hormone secretion.

OBJECTIVE: To treat anovulatory women with high plasma LH levels with unkei-to. STUDY DESIGN: A total of 100 patients with polycystic ovary syndrome (n = 38) or non-polycystic ovary syndrome (n = 62) were allocated randomly into two groups. Endocrine levels (FSH, LH and estradiol), follicle growth and response to unkei-to were compared for 52 subjects in the unkei-to group and 48 subjects in the control group. RESULTS: Unkei-to induced significant decreases in plasma LH in polycystic ovary syndrome and non-polycystic ovary syndrome with high LH levels. Plasma estradiol levels increased significantly (43.5%) in eight weeks of treatment with unkei-to. Significant development of the dominant follicle was also observed in patients treated with unkei-to. When women suffering from ovulatory failure or irregular menstruation and having high plasma LH concentration were treated with unkei-to for eight weeks, a reduction in the serum LH level of at least 1 SD from baseline was noted in 45.5% of polycystic ovary syndrome patients and in 80.0% of non-polycystic ovary syndrome patients. The mean rate of reduction of serum LH was 22.2 +/- 35.7% in polycystic ovary syndrome patients and 49.7 +/- 15.3% in non-polycystic ovary syndrome patients. This reduction was significant in the non-polycystic ovary syndrome patients (P = .030). The rate of menstrual cycle improvement, including successful ovulation, was 50.0% in the polycystic ovary syndrome group and 60.0% in the non-polycystic ovary syndrome group, with no significant difference between the two groups.

Adult↗
PubMed2000

Enhancement of Fc gamma R- and CR3-mediated neutrophil phagocytosis by cerebrosides.

There is increasing evidence that the ligation of adhesion molecules such as L-selectin can activate phagocytes to their full inflammatory potential. Sulfatide has been established as ligand for L-selectin and shown to trigger intracellular signals in human neutrophils. However, it remains unclear whether the ligation of L-selectin with sulfatide affects neutrophil phagocytosis. We studied the effects of sulfatide upon Fc gamma R- and CR3-mediated human neutrophil phagocytosis. Adhesion of the cells to a sulfatide-coated surface resulted in a dose-dependent enhancement of phagocytosis mediated via Fc gamma R or CR3, or both receptors. Galactocerebroside, but not glucocerebroside, also enhanced phagocytosis by neutrophils; therefore, galactose residue is thought to be required on ceramide molecules for the activation. Chymotrypsin-treated neutrophils, from which most L-selectin had been removed, reacted with sulfatide and galactocerebroside to enhance phagocytosis. These results suggest that an unidentified receptor for these cerebrosides exists on neutrophils and participates in the enhancement of phagocytosis.

Cell Adhesion↗
PubMed2000

Asymmetric conjugate 1,4-addition of arylboronic acids to alpha, beta-unsaturated esters catalyzed by Rhodium(I)/(S)-binap

Arylboronic acids underwent the conjugate 1,4-addition to alpha, beta-unsaturated esters to give beta-aryl esters in high yields in the presence of a rhodium(I) catalyst. The addition of arylboronic acids to isopropyl crotonate resulted in high yields and high enantioselectivity exceeding 90% ee in the presence of 3 mol % of Rh(acac)(C(2)H(4))(2) and (S)-binap at 100 degrees C. The rhodium/(S)-binap complex provided (R)-3-phenylbutanoate in the addition of phenylboronic acid to benzyl crotonate. The effects on the enantioselectivity of chiral phosphine ligands, rhodium precursors, and substituents on alpha,beta-unsaturated esters are discussed, as well as the mechanistic aspect of the catalytic cycle.

Journal Article↗
PubMed2000

Distribution of dorsal-forming activity in precleavage embryos of the Japanese newt, Cynops pyrrhogaster: effects of deletion of vegetal cytoplasm, UV irradiation, and lithium treatment.

Two types of axis-deficient embryos developed after deletion of the vegetal cytoplasm: wasp-shaped embryos and permanent-blastula-type embryos. In situ hybridization revealed that neither type of axis-deficient embryo expressed goosecoid or pax-6. brachyury was expressed in the constricted waist region of the wasp-shaped embryos but was not expressed in the permanent-blastula-type embryos. Further, we examined the effect of UV irradiation on Japanese newt embryos. Surprisingly, UV-irradiated Japanese newt eggs formed hyperdorsalized embryos. These embryos gastrulated in an irregular circular fashion with goosecoid expression in the circular equatorial region. At tailbud stage, these embryos formed a proboscis which is very reminiscent of that formed in hyperdorsalized Xenopus embryos. Transplantation of the marginal region of the UV-irradiated embryos revealed that the entire marginal zone had organizer activity. Thus we conclude that UV hyperdorsalizes Japanese newt embryos. Finally, lithium treatment of normal embryos at the 32-cell stage also resulted in hyperdorsalization. Lithium treatment of vegetally deleted embryos had two distinct results. Lithium treatment of permanent-blastula-type embryos did not result in the formation of dorsal axial structures, while the same treatment reinduced gastrulation and dorsal axis formation in the wasp-shaped embryos. Based on these results, we propose a model for early axis specification in Japanese newt embryos. The model presented here is fundamentally identical to the Xenopus model, with some important modifications. The vegetally located determinants required for dorsal development (dorsal determinants, DDs) are distributed over a wider region at fertilization in Japanese newt embryos than in Xenopus embryos. The marginal region of the Japanese newt embryo at the beginning of development overlaps with the field of the DDs. Gastrulation is very likely to be a dorsal marginal-specific property, while self-constriction is most probably a ventral marginal-specific property in Japanese newt embryos.

Animals↗
PubMed2000

Developmental expression of maf-1 messenger ribonucleic acids in rat kidney by in situ hybridization histochemistry.

maf is a family of oncogenes, originally identified from the avian oncogenic retrovirus AS42, which encodes a nuclear bZip transcription factor protein. It has been reported that maf family genes have critical roles in embryological development and cellular differentiation. In this study, the distribution of maf-1 genes, the rat homologues of mafB, was examined in rat kidneys at the embryonic stages from 13 days, gestation (E13) through E21 and then 1, 2, 4, and 8 weeks after birth by in situ hybridization with (35)S-labeled antisense riboprobes. The cellular localization was determined using double in situ hybridization. Expression of maf-1 mRNA appeared weakly on E15 and was restricted to glomerular visceral epithelial cells during the pre- and postnatal stages until 2 weeks after birth and then gradually diminished. Double in situ hybridization demonstrated that maf-1 mRNA-positive cells in glomerulus also expressed Pod-1 gene, suggesting that maf-1 mRNA was expressed in the podocyte. These findings suggest that the expression of maf-1 gene may be involved in embryological development and/or differentiation of the kidney.

Animals↗
PubMed2000

Reduction in excessive muscle tone by selective depletion of serotonin in intercollicularly decerebrated rats.

Intercollicular decerebration in animals induces sustained facilitation of muscle tone of the limbs and this animal model has been used to assess centrally acting muscle relaxants. We have examined the involvement of central and spinal cord serotonergic pathways in the onset of excessive muscle tone in an intercollicularly decerebrated rat. Descending serotonergic pathways are known to modulate, directly or indirectly, the excitability of spinal cord motoneurons and it is inferred that serotonin (5-HT) plays an important role in locomotion. Alteration of muscle tone has been investigated in 5-HT-depleted rats with a neurotoxin, 5, 7-dihydroxytryptamine (5,7-DHT) after pretreatment with desipramine. Intracerebroventricular (i.c.v.) administration of 5,7-DHT reduced 5-HT content in the forebrain to 50.5% and that in the spinal cord to 10.5%, while intrathecal (i.t.) administration of 5,7-DHT decreased 5-HT content in the spinal cord to 8.9% without causing any change in the forebrain. In contrast, noradrenaline or dopamine content was not affected by the neurotoxin in both tissues. These treatments significantly attenuated the muscle tone in the animal models. Moreover, the measurement of 5-HT and 5-hydroxyindoleacetic acid content in intact rats after decerebration showed that facilitation of the 5-HT turnover in the spinal cord, but not in the forebrain, was enhanced compared with sham-operated rats. These findings suggest that the descending serotonergic pathways are essential to induce excessive muscle tone in the intercollicular decerebrated rats and that 5-HT antagonists might be candidates for centrally acting muscle relaxants.

5,7-Dihydroxytryptamine↗
PubMed2000

Sites of action of protein kinase C and phosphatidylinositol 3-kinase are distinct in oxidized low density lipoprotein-induced macrophage proliferation.

Oxidized low density lipoprotein (Ox-LDL) can induce macrophage proliferation in vitro. To explore the mechanisms involved in this process, we reported that activation of protein kinase C (PKC) is involved in its signaling pathway (Matsumura, T., Sakai, M., Kobori, S., Biwa, T., Takemura, T., Matsuda, H., Hakamata, H., Horiuchi, S., and Shichiri, M. (1997) Arterioscler. Thromb. Vasc. Biol. 17, 3013-3020) and that expression of granulocyte/macrophage colony-stimulating factor (GM-CSF) and its subsequent release in the culture medium are important (Biwa, T., Hakamata, H., Sakai, M., Miyazaki, A., Suzuki, H., Kodama, T., Shichiri, M., and Horiuchi, S. (1998) J. Biol. Chem. 273, 28305-28313). However, a recent study also demonstrated the involvement of phosphatidylinositol 3-kinase (PI3K) in this process. In the present study, we investigated the role of PKC and PI3K in Ox-LDL-induced macrophage proliferation. Ox-LDL-induced macrophage proliferation was inhibited by 90% by a PKC inhibitor, calphostin C, and 50% by a PI3K inhibitor, wortmannin. Ox-LDL-induced expression of GM-CSF and its subsequent release were inhibited by calphostin C but not by wortmannin, whereas recombinant GM-CSF-induced macrophage proliferation was inhibited by wortmannin by 50% but not by calphostin C. Ox-LDL activated PI3K at two time points (10 min and 4 h), and the activation at the second but not first point was significantly inhibited by calphostin C and anti-GM-CSF antibody. Our results suggest that PKC plays a role upstream in the signaling pathway to GM-CSF induction, whereas PI3K is involved, at least in part, downstream in the signaling pathway after GM-CSF induction.

Androstadienes↗
PubMed2000

Molecular cloning and functional characterization of the mouse mafB gene.

The Maf family of the transcription factors plays a pivotal role in controlling development and cellular differentiation. To clarify the molecular mechanisms controlling mafB expression, a genomic clone of the mouse mafB gene was isolated and analyzed. RNase protection analysis determined the transcription initiation site at 389 bp upstream from the translation initiation site. The 3' end of the gene is located at 946 bp downstream from the termination codon. The gene lacks intron structure. Sequence analysis showed a TATA-like sequence (5'-GATAAAA-3') and an inverted CCAAT-box (5'-ATTGG-3') in the promoter region. Upstream of these sequences, there are several potential regulatory elements, including two GC-boxes (5'-GGGCGG-3'), and a palindromic sequence (5'-GTCAGCTGAC-3') which contains two Maf recognition elements (MARE, 5'-GCTGAC-3') and an E-box (5'-CAGCTG-3'). Transient transfection analysis with the 5'-flanking region of the mafB gene demonstrated that these elements are important for mafB gene expression. In addition, cotransfection analysis indicated that the MyoD activates the mouse mafB promoter and the gene is positively auto-regulated by its own product.

Animals↗