Cytokine inducible matrix metalloproteinase expression in immortalized rat chondrocytes is independent of nitric oxide stimulation

Summary The objective of this study was to determine if an immortalized mammalian chondrocyte cell line had a profile of matrix metalloproteinase (MMP) expression that was consistent with what has been reported for primary chondrocytes in vitro and in vivo. A combination of zymography, Western, and Northern analysis was used to examine the expression of MMPs that are relevant to cartilage degradation. Both interleukin-1β and tumor necrosis factor α induced a 4- to 9-fold increase in the level of MMP-9 expression in conditioned media, and a 17- to 24-fold increase in MMP-3 mRNA. Other compounds such as basic fibroblast growth factor and staurosporine each increased MMP-9 expression individually and potentiated the effects of the two cytokines. Transforming growth factor β had no positive or inhibitory effects. N-methyl arginine blocked the increase in nitric oxide observed following treatment with the cytokines but did not prevent the increased expression of MMPs. The pattern of metalloproteinase expression observed in IRC cells and the response to cytokines is very similar to what has been reported during the pathogenesis of osteoarthritis. The IRC cells should be useful as a model system to study basic mechanisms controlling chondrocyte MMP expression and to identify pharmacological modulators of this process.     

Body Anthropometry and the Risk of Hip and Wrist Fractures in Men: Results from a Prospective Study

Available epidemiological information on the associations between body anthropometry and the incidence of fractures in men is limited. We therefore prospectively investigated the association between body anthropometry and the incidence of hip and wrist fractures from low and moderate trauma among 43,053 men who were 40 years to 75 years of age in 1986 when they first enrolled in the Health Professionals Follow-Up Study. After 8 years of follow-up, 201 wrist fracture cases and 56 hip fracture cases were reported. Greater height was associated with significant elevations in both hip and wrist fractures, whereas nonsignificant inverse associations were observed with weight and body mass index. Men in the highest quintile of waist circumference had a relative risk (RR) of 2.57 (95% confidence interval [CI] 0.64 to 10.3) for hip fracture and 2.05 (95% CI 1.06 to 3.96) for wrist fracture when compared with men in the lowest quintile. Waist-to-hip ratio was also positively related to fracture incidence; comparing highest with lowest quintile, the RRs were 3.92 (95% CI 1.07 to 14.3) for hip fracture and 1.50 (95% CI 0.85 to 2.66) for wrist fracture. These anthropometric indicators, in particular waist-to-hip ratio, may be useful for the prediction of hip fracture in adult men.     

Coassembly of big conductance Ca2+-activated K+ channels and L-type voltage-gated Ca2+ channels in rat brain

Based on electrophysiological studies, Ca(2+)-activated K(+) channels and voltage-gated Ca(2+) channels appear to be located in close proximity in neurons. Such colocalization would ensure selective and rapid activation of K(+) channels by local increases in the cytosolic calcium concentration. The nature of the apparent coupling is not known. In the present study we report a direct coassembly of big conductance Ca(2+)-activated K(+) channels (BK) and L-type voltage-gated Ca(2+) channels in rat brain. Saturation immunoprecipitation studies were performed on membranes labeled for BK channels and precipitated with antibodies against alpha(1C) and alpha(1D) L-type Ca(2+) channels. To confirm the specificity of the interaction, precipitation experiments were carried out also in reverse order. Also, additive precipitation was performed because alpha(1C) and alpha(1D) L-type Ca(2+) channels always refer to separate ion channel complexes. Finally, immunochemical studies showed a distinct but overlapping expression pattern of the two types of ion channels investigated. BK and L-type Ca(2+) channels were colocalized in various compartments throughout the rat brain. Taken together, these results demonstrate a direct coassembly of BK channels and L-type Ca(2+) channels in certain areas of the brain.     

Effects of wounds on the terpene content of twigs of maritime pine (Pinus pinaster Ait.)

Summary The effect of wounds on the volatile terpene composition of the living bark of Pinus pinaster Ait. (maritime pine) twigs was investigated with respect to the processes of mono- and sesquiterpene hydrocarbon biosynthesis. The large increase in the amounts of - and -pinene is a characteristic feature after a mechanical injury, whereas the quantities of the other terpenes are only slightly increased. This is due to the reactivation of the resin duct secretory cells of primary origin located in cortical tissues. The effect of wounding is observed over a long period and the terpene profiles are very different at the end of the experiments as compared with the initial profiles of the same tissues. The traumatic essential oil (obtained after mechanical traumatism) resembles an oleoresin extracted from tissues of secondary origin. Statistical analysis underlines the effects of the between-tree variations and of the dates of application of the wound.     

Identification of the Forms of Vitamin B6 Present in the Culture Media of “Vitamin B6 Control” Mutants

An Escherichia coli mutant resistant to isoniazid (WG497) contained 0.6 mumole of extracellular pyridoxamine and pyridoxamine phosphate in the early stationary phase. A suppressed lysine mutant (AT1024) contained 1.4 mumoles of pyridoxal phosphate under the same conditions. The internal concentration of vitamin B(6) was one-half of normal for AT1024 and increased fivefold for WG497.     

Geographic variation in diapause incidence, life-history traits, and climatic adaptation in Drosophila melanogaster

In Drosophila melanogaster, exposure of females to low temperature and shortened photoperiod can induce the expression of reproductive quiescence or diapause. Diapause expression is highly variable within and among natural populations and has significant effects on life-history profiles, including patterns of longevity, fecundity, and stress resistance. We hypothesized that if diapause expression is associated with overwintering mechanisms and adaptation to temperate environments, the frequency of diapause incidence would exhibit a latitudinal cline among natural populations. Because stress resistance and reproductive traits are also clinal in this species, we also examined how patterns of fecundity and longevity varied with geography and how stress resistance and associated traits differed constitutively between diapause and nondiapause lines. Diapause incidence was shown to vary predictably with latitude, ranging from 35% to 90% among natural populations in the eastern United States Survivorship under starvation stress differed between diapause and nondiapause lines; diapause phenotypes were also distinct for total body triglyceride content and the developmental distribution of oocytes in the ovary following stress exposure. Patterns of longevity, fecundity, and ovariole number also varied with geography. The data suggest that, for North American populations, diapause expression is functionally associated with overwintering mechanisms and may be an integral life-history component in natural populations.     

Pollination ecology of Yucca elata

The pollination biology of a population of 250 Yucca elata (Liliaceae) plants was studied in southern New Mexico. Yucca elata and the prodoxid yucca moth Tegeticula yuccasella have a mutualistic association that is essential for the successful sexual reproduction of both species. However, a wide range of other invertebrate species visit flowers during the day and at night. Our aim was to quantify the role of yucca moths and other invertebrate visitors in pollination and fruit set, using manipulative field experiments. Inflorescences were bagged during the day or night (N=12 inflorescences) to restrict flower visitors to either nocturnal or diurnal groups. Yucca moths were active exclusively nocturnally during the flowering period and thus did not visit inflorescences that were unbagged during the day. None of the 4022 flowers exposed only to diurnal visitors set fruit, whereas 4.6% of the 4974 flowers exposed only to nocturnal visitors (including yucca moths) produced mature fruit. The proportion of flowers producing fruit in the latter treatment was not significantly different from unbagged control inflorescences. In a series of experimental manipulations we also determined that: (1) flowers opened at dusk and were open for two days on average, but were only receptive to pollen on the first night of opening; (2) pollen must be pushed down the stigmatic tube to affect pollination; and (3) most plants require out-cross pollination to produce fruit. The combination of these results strongly suggests that yucca moths are the only species affecting pollination in Y. elata, and that if another species was to affect pollination, it would be a rare event.     

Inhibition of nitrite assimilation by uncouplers of phosphorylation

Summary Carbonyl cyanide m-chlorophenylhydrazone (CCCP) and pentachlorophenol (PCP), two powerful uncouplers of phosphorylation, specifically inhibit the assimilation of nitrite in the course of nitrate reduction. These results support our former conclusion that high-energy phosphate is involved in the metabolism of nitrite.