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Hiroshi Katagiri

Publications and source records attributed to Hiroshi Katagiri.

12 recordsLinked to original sources
PubMed2006

Oligoresorcinols fold into double helices in water.

We report the first double helices with a controlled helicity in water based on oligoresorcinols as a new, simplest water-soluble structural motif. The molecular strands of the oligoresorcinols self-assemble into double helices with the aid of aromatic interactions in water as characterized by 1H NMR and absorption spectroscopies together with the X-ray crystallographic study of the pentamer. The double helix formation is sensitive to the chain length, solvent composition, and temperature. Moreover, a bias in the screw sense of the double helices was achieved by covalently attaching chiral substituents to both ends of the molecular strands.

Magnetic Resonance Spectroscopy↗
PubMed2006

Indoor glutaraldehyde levels in the endoscope disinfecting room and subjective symptoms among workers.

We measured the environmental glutaraldehyde (GA) levels during the disinfection of endoscopes and also investigated the subjective symptoms of the workers engaged in that work. At 6 hospitals in the Tokyo and Kanagawa area, 8 rooms for endoscope washing and disinfecting the endoscopy equipment were surveyed. The geometric mean environmental GA levels in the 8 rooms were 1.3 to 19.6 ppb. The personal exposure levels at the time of replacing the antiseptic solution containing GA in two of the disinfecting rooms were 94.2 and 84.9 ppb. Subjective symptoms such as ophthalmic, nasal, respiratory, pharyngeal symptoms and nausea were more prevalent among workers than controls as evidenced from the questionnaire survey.

Adult↗
PubMed2006

[Active vitamin D and vitamin K as therapeutic agents for osteoporosis].

Active vitamin D has been most widely used in Japan for the treatment of osteoporosis. However, clinical evidence for its efficacy as an anti-osteoporotic drug is scarce in terms of fracture prevention. Recent reports suggest that active vitamin D may prevent fracture not only through enhancement of intestinal calcium absorption but also by improving bone quality and/or strength independently of bone mass and by improving neuromuscular function to reduce the number of fall. Low serum concentrations of vitamin K have been reported in patients with osteoporosis, and serum osteocalcin appears to be undercarboxylated in these individuals, a process dependent on vitamin K. Undercarboxylated osteocalcin is also a significant risk for hip fracture. Clinical studies in Japan suggest that menatetrenone (vitamin K2) reduces skeletal losses and, in a small randomized clinical trial, it reduced the rate of vertebral fractures. Menatetrenone is currently used in Japan, the Republic of Korea and Thailand.

Humans↗
PubMed2005

Increasing incidence of hip fracture in Tottori Prefecture, Japan: trend from 1986 to 2001.

We conducted a survey of all hip fractures in patients 35 years old and over during 1998-2001 in Tottori Prefecture, Japan, and compared them with those reported previously. The survey found 604, 671, 710, 729 patients, in 1998, 1999, 2000, and 2001, respectively. The mean age- and gender-specific incidences (per 100,000 person-years) for men were 108.0, 209.0, 449.1, and 780.0 in the age groups of 70-74, 75-79, 80-84 and over 84, respectively, and those for women were 249.1, 505.8, 1,115.4, and 2,066.4, respectively. The expected numbers of patients in 1998 were 1.23 and 1.42 times those in 1986, and those in 2001 were 1.61 and 1.48 times those in 1986, for men and women, respectively, and the increases with time for both genders were significant. It was concluded that there was a significant increase in the incidence rates of hip fracture from 1986 to 2001.

Adult↗
PubMed2005

Dual memory of enantiomeric helices in a polyacetylene induced by a single enantiomer.

We report the dual memory of both the enantiomeric right- and left-handed helical conformations induced in a polyacetylene based on the temperature-stimulated helicity inversion of the polymer. The polyacetylene folds into a one-handed helix induced by noncovalent bonding interactions with a single enantiomeric amine. The induced helix underwent a reversible inversion of the helicity by temperature. The diastereomeric right- and left-handed helices obtained at different temperatures could be further memorized when the optically active amine was replaced by an achiral diamine, generating right- and left-handed helices of the mirror images of each other. Consequently, both enantiomeric helices can be produced with a high efficiency from dynamically diastereomeric helical polyacetylenes induced by a single enantiomer.

Acetylene↗
PubMed2003

Synthesis of all stereoisomers of sulfinylcalix[4]arenes.

All four stereoisomers of p-tert-butylsulfinylcalix[4]arene [4(rccc), 4(rcct), 4(rctt), and 4(rtct)], arising from the disposition of the four sulfinyl groups with respect to the mean plane of the four bridging sulfur atoms, have been prepared via oxidation of p-tert-butylthiacalix[4]arene (2) or its tetra-O-benzyl ethers 5 of defined conformations. Thus, treatment of 2 with 4.4 molar equiv of NaBO(3).4H(2)O gave the rtct and rctt isomers in 27% and 17% yields, respectively, while oxidation of cone 5 (5(C)) and partial cone 5 (5(PC)) proceeded stereoselectively to give, after debenzylation of the resulting tetrasulfoxides 12 and 15, the rccc and rcct isomers in 56% and 28% yields, respectively, based on 5. The sulfinylcalix[4]arenes 4 were treated with iodomethane in the presence of a base to give the corresponding tetramethyl ethers 16, the structures of which in regard to the disposition of the sulfinyl groups and the conformation of the phenol units were determined by X-ray crystallography. Also reported is the synthesis of all four conformational isomers of tetra-O-benzyl ether of 2 (5(C), 5(PC), 5(1,2-A), and 5(1,3-A)).

Journal Article↗
PubMed2002

[Pitfalls in bone mineral measurement].

In order to improve the reproducibility of bone mineral measurement, measurement needs to be repeated on the same position of the patients. Although lumbar bone mineral measurement is recommended in post menopausal osteoporosis, peripheral bone mineral reduction may precede lumbar bone mineral reduction in some secondary osteoporosis. The antiresorptive agents increase lumbar or proximal femoral bone mineral density; however, little changes are observed in peripheral bone mineral density by the treatment.

English Abstract↗