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Biomedical subjects

Hiroyuki Usuda

Publications and source records attributed to Hiroyuki Usuda.

9 recordsLinked to original sources
PubMed2006

A case of preclinical Cushing's syndrome associated with diurnal rhythms of ACTH and cortisol in blood: correlation with histological findings.

We describe a case of adrenocortical adenoma with preclinical Cushing's syndrome demonstrating diurnal rhythms of ACTH and cortisol in blood. A 50-year-old man was admitted to the hospital for the evaluation of incidental right adrenal mass with hyperglycemia and hypertension. On admission, there were no signs of clinical manifestation of hypercortisolism. The basal levels of cortisol (9.3 microg/dl) and ACTH (9.4 pg/ml) at 0800 h were not elevated and these diurnal rhythms were maintained. One or 8 mg of dexamethasone given orally overnight suppressed the plasma ACTH but not serum cortisol. Ultrasonogram, CT and scintiscan of (131)I adosterol all demonstrated an enlarged adrenal mass in the right adrenal gland. The right adrenal gland was subsequently resected by laparoscopic surgery. Histopathological findings of resected adrenal tumor were consistent with adrenocortical adenoma. Adjacent non-neoplastic adrenal tissue demonstrated adrenocortical atrophy but DHEA-sulfotransferase immunoreactivity in the zona reticularis was detected.

Adrenal Cortex Neoplasms↗
PubMed2006

Ethylene biosynthesis regulation in tomato fruit from the F1 hybrid of the ripening inhibitor (rin) mutant.

We have previously shown a significant decrease in the ethylene production in tomato fruit from the RIN/rin genotype. In this present study, we evaluated the amount of 1-aminocyclopropane-1-carboxylic acid (ACC) and the gene expression and enzymatic activities of ACC synthase (ACS) and ACC oxidase (ACO) to find which type of regulation influenced this low ethylene production. The results suggest that the decreased ethylene production was due to transcriptional regulation of the ACS and ACO genes by the heterozygous effect of the rin gene.

Amino Acid Oxidoreductases↗
PubMed2005

Total synthesis of (+/-)-garsubellin A.

The first total synthesis of garsubellin A, a neurotrophic compound with potent choline acetyltransferase-inducing activity, is described. Keys for success were (1) stereoselective intermolecular aldol reaction at the C-4 position with acetaldehyde, (2) stereoelective Claisen rearrangement to introduce an allyl group to the most sterically crowded position at C-6, (3) ring-closing metathesis to construct the B-ring, and (4) Wacker-type oxidative C-ring formation. This synthetic route can be extended to an asymmetric synthesis of garsubellin A using the Koga catalytic enantioselective alkylation, which produced enantioenriched alpha-prenyl cyclohexenone with excellent enantioselectivity (95% ee).

Molecular Conformation↗
PubMed2005

Composite paraganglioma-ganglioneuroma of the urinary bladder.

Presented herein is the case of a 73-year-old man, complaining of dysuria, who had a composite paraganglioma-ganglioneuroma of the urinary bladder (CPGUB). At cystoscopy a submucosal tumor was found in the urinary bladder and resected after transurethral biopsy. The levels of serum catecholamine and 24 h urinary excretion of catecholamine and vanillylmandelic acid were elevated. Grossly, the resected tumor, measuring 4 x 3 x 2.5 cm, had a brownish cut surface with no necrosis and hemorrhage. Histologically, the tumor had alternating cellular and fibrous areas. The cellular areas consisted of polygonal cells, arranged in well-defined nests (Zellballen) and positive for Grimelius staining, with abundant amphophilic to acidophilic cytoplasm, occasionally containing eosinophilic hyaline globules and brown pigments. Although the nuclei of several polygonal cells were bizarre, mitoses and vascular invasion were not found. Fibrous areas consisted of spindle cells, resembling Schwann cell, admixed with ganglionic cells. To the authors' knowledge, only four cases of CPGUB have been reported in the English-language literature. Detailed reported cases and the present case showed no malignant features, such as extra-bladder infiltration and metastasis, and no recurrence in the short length of follow up. Accumulation of long-term follow-up cases may provide valuable prognostic information on this composite tumor.

Aged↗
PubMed2004

Challenge toward structural complexity using asymmetric catalysis: target-oriented development of catalytic enantioselective Diels-Alder reaction.

A new method for the catalytic enantioselective Diels-Alder reaction using polysubstituted silyl enol ethers as dienes is described. High enantioselectivity (up to 92% ee) was produced using a catalyst generated from FeBr(3) and AgSbF(6) in a 1:2 ratio and aryl-pybox (aryl = Ph or p-ethoxyphenyl). This reaction should facilitate the enantioselective synthesis of polycyclic acylphloroglucinols such as hyperforin or garsubellin A, which are currently of interest from synthetic and medicinal points of view.

Journal Article↗
PubMed2003

Catalytic enantioselective Strecker reaction of ketoimines.

A new method for the catalytic enantioselective Strecker reaction (cyanation) of N-diphenylphosphinoyl ketoimines is described. The asymmetric catalyst is a chiral gadolinium complex prepared from Gd(OiPr)3 and the d-glucose-derived ligand 3 in a 1:2 ratio. The reaction has a broad substrate generality, giving high enantioselectivity from aromatic, ethyl, primary alkyl, and alpha,beta-unsaturated ketoimines. The products could be easily converted to disubstituted alpha-amino acids and their derivatives.

Catalysis↗
PubMed2003

Morphological investigation of two sibling autopsy cases of mitochondrial trifunctional protein deficiency.

Two sibling autopsy cases of type 2 mitochondrial trifunctional protein (MTP) deficiency are described. MTP is an enzyme complex involved in the mitochondrial beta-oxidation of fatty acids, which is the major pathway for energy production in heart and skeletal muscle. Both cases showed similar pathological findings. Numerous small foci of degeneration of muscle cells and cardiac myocytes were detected. Some of these cells had condensed or fragmented nuclei and most of them were positively stained using the deoxyuridine triphosphate nick-end labeling method. The lipid staining of both cases showed a small- to medium-sized fatty, vesicular morphology for liver cells, muscle cells, cardiac myocytes and proximal tubular cells of the kidney. Bone marrow was severely hypoplastic, and cortical thymocytes were markedly reduced in number. Neither case had hepatic fibrosis nor cirrhosis. The definitive diagnosis of type 2 MTP deficiency was made by verifying completely defective MTP-alpha and MTP-beta subunits in cultured skin fibroblasts of one of 2 patients. Our patients' signs indicate that there is a wider pathological spectrum of type 2 MTP deficiency, while very few autopsy cases of type 2 MTP deficiency have been confirmed. Pathologists should consider the possibility of type 2 MTP deficiency or other beta-oxidation defects in cases of sudden infant death, fatty infiltration of viscera or cardiomyopathy.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed2002

Studies toward the total synthesis of garsubellin A: a concise synthesis of the 18-epi-tricyclic core.

[reaction: see text] During studies directed toward the total synthesis of garsubellin A, a concise stereocontrolled synthesis of the 18-epi-tricyclic compound 3 was achieved. Key steps were a one-pot stereoselective construction of the bicyclic lactone 23 followed by a formal migration to the bicyclo[3.3.1]nonane-1,3,5-trione and an intramolecular Wacker-type tetrahydrofuran ring formation.

Choline O-Acetyltransferase↗