Temperature dependence of the electron spin-lattice relaxation rate from pulsed EPR of CUA and heme a in cytochrome c oxidase

This work shows the feasibility of using pulsed, saturation recovery EPR to study directly the magnetic relaxation properties of metal centers in cytochrome c oxidase in the 1.5-20 K range. Heme a and CuA both showed remarkably similar Tn temperature dependences in their spin-lattice relaxation rates. Either both are in environments with very similar protein backbone configurations (Stapleton, H.J., J.P. Allen, C.P. Flynn, D.G. Stinson, and S.R. Kurtz, 1980, Phys. Rev. Lett., 45:1456-1459; Allen, J.P., J.T. Colvin, D.G. Stinson, C.P. Flynn, and H.J. Stapleton, 1982, Biophys. J., 38:299-310), or the CuA is relaxed by nearby heme a. Spin-lattice relaxation of the nitrosylferrocytochrome a3 center in mixed valence oxidase showed enhancement of relaxation by a nearby paramagnetic center, most likely heme a.     

Effects of ozone on meiotic chromosomes of Vicia faba.

All of the levels of ozone used in these experiments caused morphological damage to plants of Vicia faba L., but only the dose of 200 parts per hundred million for 4 h or 8 h caused chromosomal damage in the microsporocytes. Significant chromosomal damage appeared 24 h after fumigation in metaphase I and anaphase I - telophase I but no significant damage was found in anaphase II - telophase II. This observation suggests that chromosomes are more susceptible to ozone during early stages of meiosis than at later stages. Chromosomal damage was of two types: physiological, as suggested by chromosome stickiness and physical, as indicated by bridges, fragments, and micronuclei.     

Hospital Differences in Cesarean Deliveries in Massachusetts (US) 2004–2006: The Case against Case-Mix Artifact

Objective

We examined the extent to which differences in hospital-level cesarean delivery rates in Massachusetts were attributable to hospital-level, rather than maternal, characteristics.

Methods

Birth certificate and maternal in-patient hospital discharge records for 2004–06 in Massachusetts were linked. The study population was nulliparous, term, singleton, and vertex births (NTSV) (n = 80,371) in 49 hospitals. Covariates included mother''s age, race/ethnicity, education, infant birth weight, gestational age, labor induction (yes/no), hospital shift at time of birth, and preexisting health conditions. We estimated multilevel logistic regression models to assess the likelihood of a cesarean delivery

Results

Overall, among women with NTSV births, 26.5% births were cesarean, with a range of 14% to 38.3% across hospitals. In unadjusted models, the between-hospital variance was 0.103 (SE 0.022); adjusting for demographic, socioeconomic and preexisting medical conditions did not reduce any hospital-level variation 0.108 (SE 0.023).

Conclusion

Even after adjusting for both socio-demographic and clinical factors, the chance of a cesarean delivery for NTSV pregnancies varied according to hospital, suggesting the importance of hospital practices and culture in determining a hospital''s cesarean rate.     

Stem cells and the rate of living

The "rate-of-living theory" is an ancient explanation of longevity which holds that aging occurs due to the exhaustion of some finite substance-breaths, heartbeats, etc. While this theory as originally conceived has been debunked, new work (Ruzankina et al. [2007], in this issue of Cell Stem Cell) suggests that mammals in fact do have a finite number of stem cell replications per life.     

IcsA, a polarly localized autotransporter with an atypical signal peptide, uses the Sec apparatus for secretion, although the Sec apparatus is circumferentially distributed

Asymmetric localization of proteins is essential to many biological functions of bacteria. Shigella IcsA, an outer membrane protein, is localized to the old pole of the bacillus, where it mediates assembly of a polarized actin tail during infection of mammalian cells. Actin tail assembly provides the propulsive force for intracellular movement and intercellular dissemination. Localization of IcsA to the pole is independent of the amino-terminal signal peptide (Charles, M., Perez, M., Kobil, J.H., and Goldberg, M.B., 2001, Proc Natl Acad Sci USA 98: 9871-9876) suggesting that IcsA targeting occurs in the bacterial cytoplasm and that its secretion across the cytoplasmic membrane occurs only at the pole. Here, we characterize the mechanism by which IcsA is secreted across the cytoplasmic membrane. We present evidence that IcsA requires the SecA ATPase and the SecYEG membrane channel (translocon) for secretion. Our data suggest that YidC is not required for IcsA secretion. Furthermore, we show that polar localization of IcsA is independent of SecA. Finally, we demonstrate that while IcsA requires the SecYEG translocon for secretion, components of this apparatus are uniformly distributed within the membrane. Based on these data, we propose a model for coordinate polar targeting and secretion of IcsA at the bacterial pole.     

Effect of intrauterine devices on uterine structure in goats. 3. Myometrial characteristics

This study investigated quantitative changes in myometrial characteristics that occur in the presence of IUDs in the ovariectomized goat uteri with and without exogenous ovarian steroid administration. The IUD alone reduced myometrial thickness and hormones increased the myometrium. IUDs significantly increased the thickness of the circular layer, while longitudinal muscle was reduced in the presence of the IUD. Both IUD and estrogen increased nuclear count per unit area in the circular muscle when acting separately and reduced the nuclear count when acting together.