Matrix GLA protein is a developmental regulator of chondrocyte mineralization and, when constitutively expressed, blocks endochondral and intramembranous ossification in the limb

Matrix GLA protein (MGP), a gamma-carboxyglutamic acid (GLA)-rich, vitamin K-dependent and apatite-binding protein, is a regulator of hypertrophic cartilage mineralization during development. However, MGP is produced by both hypertrophic and immature chondrocytes, suggesting that MGP's role in mineralization is cell stage-dependent, and that MGP may have other roles in immature cells. It is also unclear whether MGP regulates the quantity of mineral or mineral nature and quality as well. To address these issues, we determined the effects of manipulations of MGP synthesis and expression in (a) immature and hypertrophic chondrocyte cultures and (b) the chick limb bud in vivo. The two chondrocyte cultures displayed comparable levels of MGP gene expression. Yet, treatment with warfarin, a gamma-carboxylase inhibitor and vitamin K antagonist, triggered mineralization in hypertrophic but not immature cultures. Warfarin effects on mineralization were highly selective, were accompanied by no appreciable changes in MGP expression, alkaline phosphatase activity, or cell number, and were counteracted by vitamin K cotreatment. Scanning electron microscopy, x-ray microanalysis, and Fourier-transform infrared spectroscopy revealed that mineral forming in control and warfarin-treated hypertrophic cell cultures was similar and represented stoichiometric apatite. Virally driven MGP overexpression in cultured chondrocytes greatly decreased mineralization. Surprisingly, MGP overexpression in the developing limb not only inhibited cartilage mineralization, but also delayed chondrocyte maturation and blocked endochondral ossification and formation of a diaphyseal intramembranous bone collar. The results show that MGP is a powerful but developmentally regulated inhibitor of cartilage mineralization, controls mineral quantity but not type, and appears to have a previously unsuspected role in regulating chondrocyte maturation and ossification processes.

An in vitro study on the metabolism and possible drug interactions of rokitamycin, a macrolide antibiotic, using human liver microsomes

This in vitro study was designed to identify the enzyme(s) involved in the two major metabolic pathways of rokitamycin [formations of leucomycin A7 (LMA7) from rokitamycin and of leucomycin V (LMV) from LMA7] and to assess possible drug interactions using human liver microsomes. Formation of LMA7 or LMV was NADPH-independent. Anti-rat NADPH cytochrome P-450 (CYP) reductase serum, specific inhibitors, or substrates of CYP isoforms showed no effects on the formation of LMA7 or LMV. The mean Vmax and Vmax/Km for the formation of LMA7 from rokitamycin were much greater (P <.01) than those for the formation of LMV from LMA7. Two esterase inhibitors, bis-nitro-phenylphosphate and physostigmine (100 microM), inhibited the formation of LMA7 or LMV by more than 85%, whereas no appreciable inhibition occurred by several substrates of carboxylesterase (EC 3.1.1.1). Except the moderate inhibition produced by promethazine and terfenadine, theophylline, mequitazine, chlorpheniramine, and diphenhydramine showed little or no inhibition for the formation of LMA7 or LMV. Rokitamycin, LMA7, LMV, erythromycin, and clarithromycin (up to 500 microM) had no appreciable inhibition for CYP1A2-, 2C9-, and 2D6-mediated catalytic reactions. However, rokitamycin, LMA7, erythromycin, and clarithromycin inhibited the CYP3A4-catalyzed triazolam alpha-hydroxylation with IC50 (Ki) values of 5.8 (2.0), 40, 33 (20), and 56 (43) microM, respectively. It is concluded that the formations of LMA7 from rokitamycin and of LMV from LMA7 are catalyzed mainly by human esterase enzyme [possibly cholinesterase (EC3.1.1.8)]. However, whether rokitamycin would inhibit the CYP3A-mediated drug metabolism in vivo requires further investigations in patients.

Remote Pummerer Reaction via Intermolecular Through-Space Interaction between Sulfonium and Sulfenyl Sulfur Atoms

The remote Pummerer reaction of the mono-sulfoxide of p-bis(methylthio)-aromatic 1 is described. The reaction of 1 with (CF(3)CO)(2)O in CH(2)Cl(2) gave a mixture of the corresponding mono-Pummerer product 2, the bis-Pummerer product 3, and the bis-sulfide 4 in an n:1:1 ratio (n >/= 2). The 1:1 formation of 3 and 4 indicates an intermolecular interaction between sulfur atoms. The reaction with the deuterium-labeled 1-d(3)() showed that the formation of 2 occurs at the sulfenyl as well as sulfinyl groups in 1a-d(3)()-1d-d(3)(), in which the product ratio of 2-d(3)():2-d(2)() is in the range of 3.5-10. On the other hand, the Pummerer reaction of 1e-d(3)() occurred preferably at the sulfinyl group in a usual manner. The reaction of a 1:1 mixture of the bis-sulfide 4 and the bis-sulfoxide 5 with (CF(3)CO)(2)O also gave 2, 3, and 4 in a ratio similar to that for the reaction of 1. The mechanism in the present remote Pummerer reactions is discussed in light of an intermolecular through-space interaction between the sulfonium and sulfenyl sulfur atoms, and a dithia dication dimer B and/or a bis(dithia dication) cyclic dimer C are proposed as intermediates.

Retinoid signaling is required for chondrocyte maturation and endochondral bone formation during limb skeletogenesis

Retinoids have long been known to influence skeletogenesis but the specific roles played by these effectors and their nuclear receptors remain unclear. Thus, it is not known whether endogenous retinoids are present in developing skeletal elements, whether expression of the retinoic acid receptor (RAR) genes alpha, beta, and gamma changes during chondrocyte maturation, or how interference with retinoid signaling affects skeletogenesis. We found that immature chondrocytes present in stage 27 (Day 5.5) chick embryo humerus exhibited low and diffuse expression of RARalpha and gamma, while RARbeta expression was strong in perichondrium. Emergence of hypertrophic chondrocytes in Day 8-10 embryo limbs was accompanied by a marked and selective up-regulation of RARgamma gene expression. The RARgamma-rich type X collagen-expressing hypertrophic chondrocytes lay below metaphyseal prehypertrophic chondrocytes expressing Indian hedgehog (Ihh) and were followed by mineralizing chondrocytes undergoing endochondral ossification. Bioassays revealed that cartilaginous elements in Day 5.5, 8.5, and 10 chick embryo limbs all contained endogenous retinoids; strikingly, the perichondrial tissues surrounding the cartilages contained very large amounts of retinoids. Implantation of beads filled with retinoid antagonist Ro 41-5253 or AGN 193109 near the humeral anlagens in stage 21 (Day 3.5) or stage 27 chick embryos severely affected humerus development. In comparison to their normal counterparts, antagonist-treated humeri in Day 8.5-10 chick embryos were significantly shorter and abnormally bent; their diaphyseal chondrocytes had remained prehypertrophic Ihh-expressing cells, did not express RARgamma, and were not undergoing endochondral ossification. Interestingly, formation of an intramembranous bony collar around the diaphysis was not affected by antagonist treatment. Using chondrocyte cultures, we found that the antagonists effectively interfered with the ability of all-trans-retinoic acid to induce terminal cell maturation. The results provide clear evidence that retinoid-dependent and RAR-mediated mechanisms are required for completion of the chondrocyte maturation process and endochondral ossification in the developing limb. These mechanisms may be positively influenced by cooperative interactions between the chondrocytes and their retinoid-rich perichondrial tissues.

Bright light treatment for sleep-wake disturbances in aged individuals with dementia

Treatment using bright light exposure was carried out on six aged subjects with dementia in two nursing homes. Sleep logs were recorded by the staff. Bright light treatment was applied in the late morning every day. The %sleep in the lights-out period and/or the %wake in daytime increased in three subjects. In the other three subjects, sleep onset time was advanced. In all subjects abnormal behavior episodes around the lights-out time tended to be reduced. These results suggest that bright light treatment is effective in improving the sleep-wake disturbances of aged individuals with dementia.

Effects of moderately bright light on subjective evaluations in healthy elderly women

Eight healthy elderly women aged 56-72 years (mean age: 67.4 years) participated in this study. They were exposed to moderately bright light (1000 lux) for 1h in the morning every 6 days in their homes. Moderately bright light improved self evaluations for alertness, mood, motivation, happiness, refreshment, concentration and appetite after the second exposure to the light. Sleep maintenance, anxiety and integrated sleep feeling also improved after the fourth exposure to the light. The phase of rectal temperature rhythm did not change in a moderately bright light condition. These results suggest that bright light influences sleep quality and self evaluations without changing the biological rhythm phase.

[Evaluation of mycobacteria growth indicator tube (MGIT), an automated culture system for detection of mycobacteria from clinical specimens]

We compared the Mycobacteria Growth Indicator Tube 960 (MGIT 960) and Ogawa medium (OM) for the detection of mycobacteria (acid fast bacteria: AFB) using 882 sputum specimens. Overall, 120 strains of AFB were isolated by the MGIT 960 system and 99 strains of AFB were isolated by using OM. As far as Mycobacterium tuberculosis is concerned, 88 and 71 isolates were achieved by the MGIT 960 and OM respectively. A total of 28 isolates (18 isolates of M. tuberculosis and 10 isolates of nontuberculous mycobacteria: NTM) were detected by the MGIT 960 only whereas only 2 isolates (1 M. tuberculosis and 1 NTM) were detected by OM only. Of these sputum specimens, 72 were smear positive for AFB. The rates of smear negative but culture positive specimens were 8.0% (65 out of 809) for the MGIT 960 system and 6.2% (50 out of 809) for OM. The contamination rate for MGIT 960 was only 1.2%. The average time required for detection of M. tuberculosis was 14.1 days by the MGIT 960 system and 24.6 days by OM. For the NTM, the average detection time were 8.3 days for the MGIT 960 system and 22.8 days for OM. These results indicate that the MGIT 960 system allows detection of mycobacteria significantly faster than OM.

A study on the metabolism of etoposide and possible interactions with antitumor or supporting agents by human liver microsomes

The metabolism of etoposide was investigated by using human liver microsomes and nine recombinant human cytochrome P450 (CYP) isoforms to identify the CYP isoform(s) involved in the major metabolic pathway (3'-demethylation) of etoposide as well as to evaluate the possible metabolic interactions with several antitumor or supporting agents. The 3'-demethylation of etoposide followed a Michaelis-Menten one-enzyme kinetic behavior in six human liver microsomal samples. The relationships were assessed with six different human liver microsomes between the 3'-demethylation of etoposide and metabolic activities for substrate probes of the respective CYP isoforms, showing a significant correlation (r = 0. 932, P < .01) only with 6beta-hydroxylation of testosterone, a marker substrate for CYP3A4. Inhibitor/substrate probes for CYP3A4, ketoconazole, troleandomycin, verapamil and cyclosporin, or supporting agents, vincristine and prednisolone, inhibited etoposide 3'-demethylation by human liver microsomes. p-Nitrophenol, a substrate for CYP2E1, also inhibited etoposide 3'-demethylation. Among the nine recombinant human CYP isoforms, CYP3A4 exhibited the highest catalytic activity with respect to etoposide 3'-demethylation, compared with the minor activities of CYP1A2 and 2E1. Collectively, these data suggest that etoposide 3'-demethylation is mediated mainly by CYP3A4 and to a minor extent by CYP1A2 and 2E1. Furthermore, some supporting agents (vincristine and prednisolone) and the substrates of CYP3A4, which may be coadministered with etoposide during the cancer chemotherapies, inhibit the etoposide 3'-demethylation activity in vitro. The results may provide clinical implications with respect to the possible metabolic interactions between etoposide and other drugs studied herein in patients with cancer undergoing etoposide concurrently with either of them.

Sleep improvement by light in a demented aged individual

We administered daily morning bright light exposure in two separate periods to a demented aged subject in a nursing home and analyzed the sleep pattern changes from the sleep diary over 6 months. In the first light exposure period, the ratio of sleep time in night hours increased and maintained a higher value throughout the period than the previous baseline. After stopping the light exposure, the sleep pattern of the subject deteriorated. Resuming the light exposure reproduced similar sleep pattern changes. These results suggest that morning bright light exposure provides a better environment for aged persons to maintain a regular sleep-wake pattern.

Effects of short duration morning bright light in healthy elderly subjects. I: subjective feeling and ophthalmological examinations

Seven aged subjects aged 61-78 years were exposed to 6000 lx bright light for 30 min during morning hours at their homes for 1 week. Visual analog scale was recorded before bedtime and after rising to assess subjective feelings. Ophthalmological examinations were made before and after light exposure, to exclude pre-existing ocular disorders and to detect ocular damage. Furthermore, ocular fatigue was self-evaluated immediately before and after exposure. Visual analog scale results indicated that alertness reduced significantly before bedtime. Ophthalmological abnormalities were not found after exposure. These findings suggest that short duration morning bright light exposure reduces night-time vigilance.

Effects of short duration morning bright light in healthy elderly. II: sleep and motor activity

Subjective sleep feelings and motor activity were measured in seven healthy elderly subjects for 6 days. The subjects were exposed to bright light (6000 lux) for 30 min in the morning or instructed to sit in front of a desktop lighting device without light. The average level of motor activity during the night was significantly decreased in the bright light condition, compared with the controlled condition. However, daytime motor activity did not show significant differences between the two conditions. From these findings, even a short duration of morning bright light is effective in maintaining sleep without changing daytime activity.

Circadian rhythm estimation by core body temperature filtered with simultaneously recorded physiological data

In field measurements, monitoring of core body temperature is influenced by physical activities; therefore, the estimation of circadian rhythm from the data may not be exact. The purpose of this study is to design a core body temperature filter in order to reduce artifacts induced by physical activities using simultaneously recorded physiological data such as heart rate data. The effects of physical activities on core body temperature and heart rate are assessed through three experiments. Based on the above knowledge, a core body temperature filter was designed. The filter removes part of rectal temperature data as artifact when heart rate rises above a predetermined threshold. As a result, most of the spike-like noise was removed and the filtered temperature data showed sinusoidal variation more than the unfiltered data. The mesor of the estimated rhythm significantly decreased. This filtering method can provide more precise information about circadian rhythm, especially in field measurements.

Effects of genetic defects in the CYP2C19 gene on the N-demethylation of imipramine, and clinical outcome of imipramine therapy

The relationship between the genetic polymorphism of S-mephenytoin 4'-hydroxylation catalyzed by CYP2C19 and the N-demethylation of imipramine was examined in 10 Japanese depressed patients. Five patients, who were poor metabolizers of S-mephenytoin, were determined to be either homozygous for a mutation in exon 5 or heterozygous for mutations in exon 4 and exon 5 of the CYP2C19 gene. In contrast, five patients, who were extensive metabolizers, had no mutations. The demethylation index (the desipramine/imipramine ratio) was significantly lower in patients with genetic defects. Plasma levels of imipramine and 2-hydroxyimipramine normalized by the daily dose (mg) per weight (kg) were significantly higher in patients with genetic defects. This suggests that the N-demethylation of imipramine is impaired in patients with genetic defects in the CYP2C19 gene, and that genotype determination may be useful in preventing side effects induced by unexpectedly elevated levels of imipramine.