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Biomedical subjects

M Yamamoto

Publications and source records attributed to M Yamamoto.

At least 127 records · Page 7Linked to original sources
PubMed2002

Effects of imipramine on T cell subsets in olfactory bulbectomized mice.

To elucidate the immunological outcome in antidepressant therapy, the effects of acute or chronic imipramine (IMP) treatment on T cell subsets were examined in sham-operated (SO) and olfactory bulbectomized (OB) mice. Olfactory bulbectomy decreased the ratio of Lyt2-positive suppressor T cells to L3T4-positive T helper cells. Acute IMP treatment did not exert any effect on the ratio in SO nor in OB mice. Chronic IMP administration was found to significantly increase the ratio in SO and OB mice and, as a result, the ratio was significantly higher in SO mice compared with the control, while the ratio was normalized in OB mice. The present study may be suggestive of the immune activation in depression and of the immunosuppressive effects of antidepressants.

Animals↗
PubMed2002

Structure, formation, mechanical properties, and disposal of the embryo attachment system of an estuarine crab, Sesarma haematocheir.

In most decapod crustaceans, fertilized eggs extruded from the gonopore attach to ovigerous hairs within the incubation chamber of the female. The attachment is effected by an "embryo attachment system." The three continuous components of this system are the egg envelope, the funiculus, and the investment coat, which wraps around an ovigerous hair. Transmission electron microscopy (TEM) revealed that the embryo of Sesarma haematocheir is enfolded by three distinct envelopes (E1, E2, and E3), whereas the embryo attachment system is composed of only the outermost, single envelope (E1) with two sublayers (E1a and E1b). This envelope (E1) originates from the outer layer of the vitelline membrane (envelope of the ovum) with two sublayers (E1a' and E1b'). The sequence and timing of events in the formation of the embryo attachment system was determined on the basis of observations of female behavior, ultrastructure, and mechanical properties of the membranes. The egg envelope (E1a' + E1b') is not adhesive immediately after extrusion from the gonopore; but 5 min after egg-laying, it becomes adhesive-a change associated with "fusion" of the two sublayers (E1)-and attaches the eggs to the ovigerous hairs from 5 to 30 min after egg-laying. The layer E1a' always binds to an ovigerous hair at specific, electron-dense attachment sites that are distributed longitudinally on the surface of each hair. Plasticity of the egg envelope changes, and the female kneads her eggs by the movement of ovigerous setae; this movement forms the investment coat on the ovigerous hair (10-40 min after egg-laying). Thirty minutes after egg-laying, the egg envelope again divides into two sublayers (E1a and E1b), and the adhesiveness rapidly decreases. The plasticity of the envelope remains, and the funiculus is formed, accompanied by kneading of the eggs (40-90 min after egg-laying). The embryos hatch one month after incubation, and the attachment systems all slip off their ovigerous hairs by the actions of the ovigerous-hair slipping substance (OHSS). This substance appears to act specifically at the attachment sites on the hair, lysing the bond with layer E1a, and thereby disposing of the embryonic attachment system and preparing the hairs for the next clutch of embryos.

Animals↗
PubMed2002

[Clinical analysis of surgically resected multiple primary lung cancer].

Synchronous and metachronous lung cancer is occasionally encountered. Frequency of the occurrence is increasing because of recent progress of imaging technique such as high resolution CT and CT based annual lung survey. We analyzed clinical characteristics of both synchronous and metachronous lung cancer treated surgically in our facility. There were 20 cases of multiple lung cancer cases, which is consisted of 12 synchronous multiple lung cancer cases and 8 metachronous lung cancer cases. Mean age was 62 years old and there were 14 male and 6 female cases. Among synchronous group, 8 cases have multiple shadow in ipsilateral hemithorax and 4 cases in both side. Surgery was carried out according to the extent of the disease and lung reserve. Associated cancer was diagnosed stage IA or IB in all cases. Five-year survival was 58.9%. Meanwhile, as regards to metachronous group, mean interval between first cancer and second cancer was 73 months. Seven cases have contralateral second primary lung cancer and one case has ipsilateral second primary lung cancer. In 3 cases, histology of the first and the second disease were different and in 5 cases that were the same. The first procedures were complete resection with systemic mediastinal LN dissection. The second procedures were determined based on the lung reserve. Pathological stage of the second disease were either stage IA or IB. There were no operative mortality and 5 years survival was 75%. Since there is no operative mortality and the outcome seems satisfactory when the patient has enough lung reserve, aggressive surgical resection should be considered in the case of multiple primary lung cancer. There is an increasing chance of synchronous multiple primary lung cancer because of improvement of imaging system. We have to prepare new therapeutic strategy for those patients.

Aged↗
PubMed2002

Genetic polymorphisms of cytochrome P450 1A1 and risk of gallbladder cancer.

The relation between cytochrome P4501A1 (CYP1A1) gene polymorphisms and the risk of gallbladder cancer was examined. To clarify individual differences in susceptibility to gallbladder carcinogenesis, we investigated the frequency of the Mspl and Ile-Val polymorphisms of the CYP1A1 gene, in 52 patients with gallbladder cancer (32 females, 20 males) and 104 healthy controls (64 females, 40 males). We then examined the relationship between the CYP1A1 polymorphisms and the development of gallbladder cancer in members of both sexes. A statistical difference in the frequencies of the MspI and Ile-Val polymorphisms or their alleles (ml, m2 and Ile, Val) was not observed in the male patients and controls. Among females, however, the frequencies of genotypes C and Ile/Val were significantly higher (p < 0.05) in the patients than in their controls. Moreover, the frequency of the hetero genotype Ile/Val was statistically higher (p < 0.05) in the female patients than in the male patients. This study demonstrated a significant over-representation of genotypes C and Ile/Val in female patients with gallbladder cancer. Females with genotypes C and/or Ile/Val may have a high genetic susceptibility to the development of gallbladder cancer.

Alleles↗
PubMed2002

[Multivessel off-pump coronary aortic bypass grafting with an impaired and severely dilated left ventricle using the Starfish heart positioner].

Off-pump coronary artery bypass grafting (OPCAB) is gaining acceptance and is now more widely used for coronary revascularization worldwide. Accessing the vessels, particularly on the lateral and inferior walls of the heart, can sometimes be challenging while the heart is beating, especially in hearts with an impaired and severely dilated left ventricle. The Starfish heart positioner was designed to achieve optimal exposure of the lateral and inferior walls of the heart with minimal hemodynamic compromise. This device was used in a patient with a severely impaired and dilated left ventricle to successfully position the heart for quadruple bypass grafting using all in situ arterial grafts, such as bilateral international thoracic arteries (ITAs) and the right gastroepiploic artery. The degree of hematoma caused by the pressure of the suction cup of this device was minimal. This case report suggests that the use of Starfish heart positioner will facilitate and expand the ability of surgeons to easily and consistently perform OPCAB.

Coronary Artery Bypass↗
PubMed2002

A patient with thymoma and four different organ-specific autoimmune diseases.

This is the first report of a patient with four organ-specific autoimmune diseases; myasthenia gravis, type 1 diabetes mellitus, autoimmune hepatitis and Hashimoto's thyroiditis. The clinical history suggests a relationship with a non-removed thymoma. Not only the thymoma seems to have triggered these four diseases, the dramatic progressive course with an active autoimmune hepatitis and high concentrations of multiple autoantibodies was probably also associated with non-removal of the thymoma. Thymectomy should be performed in myasthenia gravis patients with thymoma and associated autoimmune diseases.

Aged↗
PubMed2001

Enantioselective intramolecular aromatic [4 + 4] photocycloaddition in crystalline state: parameters for reactivity.

Photoreactivity of seven 9-anthryl-N-(naphthylcarbonyl)carboxamide derivatives, 1a-g, in their intramolecular [4 + 4] photocycloadditions in solid state is discussed on the basis of their single-crystal X-ray analyses. The distances (d(1) and d(2)) between the two carbon atoms to be reacted, the angles (theta(1) and theta(2)), and the torsion angle (theta(3)) between the anthracene and naphthalene rings were chosen as structural parameters for reactivity. For 1a and 1e, the first example of absolute asymmetric synthesis in [4 + 4] photocycloaddition was attained. [reaction: see text]

Journal Article↗
PubMed2001

Significance of the variant and full-length forms of the very low density lipoprotein receptor in brain.

The very low density lipoprotein receptor (VLDLR) is a newly described receptor which binds to apolipoprotein E (apoE) specifically. The authors designed a synthetic peptide of 17 amino acids representing the N-terminus of the putative first ligand binding domain of human VLDLR, this being a unique domain for VLDLR. When the synthetic peptide was used as the antigen, two different monoclonal antibodies were obtained (anti-VLDLR1 and anti-VLDLR2). Expressional cloning revealed that anti-VLDLR1 recognized the variant form of VLDLR which lacks 84 bp of O-linked sugar domain and anti-VLDLR2 recognized the full length form of VLDLR. The variant VLDLR was expressed in neuroblasts as well as matrix cells and Cajal-Retzius cells in the early stages of the developing human brain; later its expression was sequentially found in glioblasts, astrocytes, oligodendrocytes and finally in myelin. The expression of a full length form of VLDLR was detected in senile plaques and some neurons and satellite glia in aged and Alzheimer brains. This suggests that the variant VLDLR is important for the developing human brain and the full length VLDLR has modified functions in aged and Alzheimer brains.

Adult↗
PubMed2001

A hydrogen-bonding receptor that binds cationic monosaccharides with high affinity in methanol.

A dicarboxylate host (1) binds cationic monosaccharides such as D-glucosamine HCl (2), D-galactosamine-HCl (3), and D-mannosamine-HCl (4) with high affinity (K1 = 8.0 x 10(4)-2.0 x 10(5) M(-1)) in methanol. In circular dichroism (CD) spectroscopy a positive exciton-coupling band was observed near 290 nm; this indicates that the saccharides are recognized by multiple point interactions. Since the corresponding neutral monosaccharides are not significantly bound, one may conclude that complex formation is primarily due to the electrostatic interaction between NH3+ in the guest and one carboxylate in the host and secondarily due to hydrogen-bonding interactions of OH groups with the other carboxylate and/or nitrogen bases. Molar ratio plots and Job plots indicate that host 1 and cationic monosaccharide guests form CD-active, pseudo-cyclic 1:1 complexes at low guest concentration followed by the formation of CD-silent, acyclic 1:2 1-saccharide complexes at high guest concentration. The possible binding modes are discussed in detail on the basis of molecular mechanics calculations and chemical shift changes in 1H NMR spectra. The results of competition experiments with several cationic reference compounds bearing fewer OH groups than 2-4 are consistent with the proposed binding model. Thus, the present study is a rare example of saccharide recognition in a protic solvent, where in general, hydrogen-bonding interactions are rarely useful because of strong solvation energy. These are apparently the strongest saccharide complexes involving noncovalent interactions between host and guest. We believe that the findings are significant as a milestone toward development of new saccharide recognition systems ultimately useful in aqueous solution.

Carrier Proteins↗
PubMed2001

Highly purified mutant E112K of cholera toxin elicits protective lung mucosal immunity to diphtheria toxin.

We demonstrated that the mutant of cholera toxin (mCT) E112K which was LPS-free supported the induction of protective immunity in mucosal (e.g. lung lavage) and systemic (e.g. serum) compartments when given nasally with vaccine-grade diphtheria toxoid (DT) to mice. Significant DT-specific mucosal IgA antibody (Ab) and serum IgG, IgA and IgM Ab responses were induced when LPS-depleted mCT E112K or native CT (nCT) was co-administered nasally with DT. The analysis of DT-specific Ab-forming cell (AFC) responses supported the Ab titers and significant numbers of DT-specific IgA AFC were present in the lungs, nasal passages and submandibular glands. Furthermore, DT-specific IgG AFC in cervical lymph nodes (CLN) and the spleen were induced in mice administered with DT nasally with either mCT or nCT. The analysis of antigen-specific T cell responses revealed that increased DT-specific CD4+ T cell proliferative and Th2-type cytokine responses were induced in mice nasally-immunized with DT and the LPS-free form of mCT. The neutralization of diphtheria toxin by Abs showed that DT-specific IgG Ab responses in serum and lung lavages of mice immunized with DT and mCT were protective. Furthermore, it was shown that an IgA-enriched fraction of lung lavages possessed diphtheria toxin-specific neutralizing activity. These results are the first demonstration that nasally co-administered mCT E112K can induce DT-specific protective Ab responses in mucosal compartments (e.g. lung lavages and the lungs).

Administration, Intranasal↗
PubMed2001

Transient occurrence of 27 kDa heat-shock protein in the terminal tubule cells during postnatal development of the rat submandibular gland.

It has been suggested that the 27 kDa heat-shock protein (Hsp27) plays a role at crucial cellular checkpoints for proliferation, apoptosis, and differentiation. We examined the immunolocalization of Hsp27 in the rat submandibular gland during postnatal development, wherein acinar cells proliferate and differentiate at earlier postnatal periods. At 2 weeks of age, weak Hsp27 immunoreactivity was distributed diffusely over all gland components. At 3 weeks, Hsp27 immunoreactivity disappeared in most parts of the acini and ducts, but was intensely accumulated in a small cell population located in the acinar center. This population was composed mostly of terminal tubule (TT) type I cells. At 4 weeks, the Hsp27-immunopositive cell population in the acinar center was composed primarily of immature (type II) acinar cells, partly of immature (granulated) intercalated duct (ID) cells, and occasionally of apoptotic cells. After 5 weeks, all acinar components became mature and were no longer immunoreactive for Hsp27. When acinar cell differentiation was accelerated by administration of isoproterenol to 3-week-old rats for 7 days, the number of Hsp27-positive cells was significantly lower than in the control gland at 4 weeks, confirming that Hsp27 expression is downregulated in mature acinar cells. These results suggest that at around 3-4 weeks in postnatal development, the centroacinar TT cells stop proliferating and begin to differentiate into acinar and ID cells, and occasionally undergo apoptosis. Hsp27 is transiently expressed in the centroacinar TT cells during this critical period, and thus may play a role in their differentiation into the immediate descendants.

Animals↗
PubMed2001

The 1.55 A resolution structure of Nicotiana alata S(F11)-RNase associated with gametophytic self-incompatibility.

The crystal structure of Nicotiana alata (ornamental tobacco) S(F11)-RNase, an S-allelic glycoprotein associated with gametophytic self-incompatibility, was determined by X-ray diffraction at 1.55 A resolution. The protein has a tertiary structure typical of members of the RNase T(2) family as it consists of a variant of the (alpha+beta) fold and has eight helices and seven strands. A heptasaccharide moiety is also present, and amino acid residues that serve as the catalytic acid and base can be assigned to His32 and His91, respectively. Two "hypervariable" regions, known as HVa and HVb, are the proposed sites of S-allele discrimination during the self-incompatibility reaction, and in the S(F11)-RNase these are well separated from the active site. HVa and HVb are composed of a long, positively charged loop followed by a part of an alpha-helix and short, negatively charged alpha-helix, respectively. The S(F11)-RNase structure shows both regions are readily accessible to the solvent and hence could participate in the process of self/non-self discrimination between the S-RNase and an unknown pollen S-gene product(s) upon pollination.

Amino Acid Sequence↗
PubMed2001

A midkine promoter-based conditionally replicative adenovirus for treatment of pediatric solid tumors and bone marrow tumor purging.

The treatment of advanced neuroblastoma (NB) or Ewing's sarcoma (ES) is one of the major challenges in pediatric oncology. Both malignancies are refractory to conventional therapies and have an extremely poor prognosis. High-dose myeloablative radiochemotherapy with autologous bone marrow or peripheral blood stem cell rescue is one of the most aggressive treatments attempted for these diseases but is often undermined by residual tumor cells contaminating the graft. Thus, in this approach, purging of tumor cells from the graft is key to the prevention of relapse after transplantation. We investigated a novel approach to eliminate tumor cells from the bone marrow or peripheral blood stem cell graft without causing stem cell damage through the use of a conditionally replicative adenovirus (Ad). ES and NB are sensitive to Ad infection, and advanced NBs express a high level of the growth/differentiation factor midkine (MK). We confirmed in this study that ES cell lines (SK-ES-1 and RD-ES) are also sensitive to Ad infection and express high levels of MK. In contrast, CD34+ stem cells are refractory to Ad infection and express very little MK. A conditionally replicative Ad in which the expression of E1 is controlled by the MK promoter achieved good levels of viral replication in NB or ES and induced remarkable tumor cell killing. On the other hand, this virus caused no damage to CD34+ cells even after 3 h of infection at a dose of 1000 multiplicity of infection. We concluded that application of this replication-competent Ad to hematopoietic grafts could be a simple but effective procedure to achieve complete tumor cell purging.

Adenoviridae↗
PubMed2001

Crystals of ternary protein-DNA complexes composed of DNA-binding domains of c-Myb or v-Myb, C/EBPalpha or C/EBPbeta and tom-1A promoter fragment.

c-Myb and the C/EBP family are transcriptional regulatory factors that act in concert to regulate the expression of myeloid-specific genes. v-Myb encoded by avian myeloblastosis virus (AMV) is a mutated form of c-Myb that contains point mutations which disrupt the cooperation with C/EBPs. To understand the mechanism of the transcriptional synergy between c-Myb and C/EBPs and the effect of the v-Myb mutations on that synergy, knowledge based on their three-dimensional structures is essential. Crystals of ternary complexes, in which various combinations of the DNA-binding domains of c-Myb or v-Myb and C/EBPalpha or C/EBPbeta are bound to a DNA fragment from tom-1A promoter, were obtained by the vapour-diffusion method. Complete diffraction data sets were obtained from each native crystal and two types of iodine-derivative crystals. A three-wavelength MAD data set was also obtained from a bromine-derivative crystal.

Animals↗
PubMed2001

Experimental and theoretical studies on ferromagnetically coupled metal complexes with imino nitroxides.

Copper(II), zinc(II), and nickel(II) complexes with tridentate imino nitroxyl diradicals, [CuCl(bisimpy)(MeOH)](PF(6)) (1), [ZnCl(2)(bisimpy)] (2), and [NiCl(bisimpy)(H(2)O)(2)]Cl x 2H(2)O (3) (bisimpy = 2,6-bis(1'-oxyl-4',4',5',5'-tetramethyl-4',5'-dihydro-1'H-imidazol-2'-yl)pyridine), were prepared, and their magnetic properties were studied. In 1, the Cu(II) ion has a square pyramidal coordination geometry, of which the equatorial coordination sites are occupied by three nitrogen atoms from the bisimpy and a chloride ion. The coordination geometry of the Zn(II) ion in 2 can be described as a trigonal bipyramid, with two chloride ions and a bisimpy. In 3, the Ni(II) ion has a distorted octahedral coordination geometry, of which four coordination sites are coordinated by the bisimpy and chloride ion, and two water molecules occupy the remaining cis positions. Magnetic susceptibility and EPR measurements revealed that in 1 and 3 the Cu(II) and Ni(II) ions with imino nitroxyl diradicals were ferromagnetically coupled, with the coupling constants J (H = -2J(ij) summation operator S(i)S(j)) of +165(1) and 109(2) cm(-1), respectively, and the intraligand ferromagnetic interactions in 1-3 were very weak. DFT molecular orbital calculations were performed on the diradical ligand, 1, and 2 to study the spin density distribution before and after coordination to the metal ions.

Journal Article↗
PubMed2001

In vivo requirements for GATA-1 functional domains during primitive and definitive erythropoiesis.

GATA-1 is a transcription factor essential for erythroid/megakaryocytic cell differentiation. To investigate the contribution of individual domains of GATA-1 to its activity, transgenic mice expressing either an N-terminus, or an N- or C-terminal zinc finger deletion of GATA-1 (Delta NT, Delta NF or Delta CF, respectively) were generated and crossed to GATA-1 germline mutant (GATA-1.05) mice. Since the GATA-1 gene is located on the X-chromosome, male GATA-1 mutants die by embryonic day 12.5. Both Delta NF and Delta CF transgenes failed to rescue the GATA-1.05/Y pups. However, transgenic mice expressing Delta NT, but not the Delta NF protein, were able to rescue definitive hematopoiesis. In embryos, while neither the Delta CF protein nor a mutant missing both N-terminal domains (Delta NTNF) was able to support primitive erythropoiesis, the two independent Delta NT and Delta NF mutants could support primitive erythropoiesis. Thus, lineage-specific transgenic rescue of the GATA-1 mutant mouse revealed novel properties that are conferred by specific domains of GATA-1 during primitive and definitive erythropoiesis, and demonstrate that the NT and NF moieties lend complementary, but distinguishable properties to the function of GATA-1.

Animals↗
PubMed2001

The mouse Hoxd13(spdh) mutation, a polyalanine expansion similar to human type II synpolydactyly (SPD), disrupts the function but not the expression of other Hoxd genes.

Polyalanine expansion in the human HOXD13 gene induces synpolydactyly (SPD), an inherited congenital limb malformation. A mouse model was isolated, which showed a spontaneous alanine expansion due to a 21-bp duplication at the corresponding place in the mouse gene. This mutation (synpolydactyly homolog, spdh), when homozygous, causes malformations in mice similar to those seen in affected human patients. We have studied the genetics of this condition, by using several engineered Hoxd alleles, as well as by looking at the expression of Hox and other marker genes. We show that the mutated SPDH protein induces a gain-of-function phenotype, likely by behaving as a dominant negative over other Hox genes. The mutation, however, seems to act independently from Hoxa13 and doesn't appear to affect Hox gene expression, except for a slight reduction of the HOXD13 protein itself. Developmental studies indicate that the morphological effect is mostly due to a severe retardation in the growth and ossification of the bony elements, in agreement with a general impairment in the function of posterior Hoxd genes.

Alleles↗