AKT1 represses gene conversion induced by different genotoxic stresses and induces supernumerary centrosomes and aneuploidy in hamster ovary cells

The oncogenic kinase AKT1 is frequently overexpressed or activated in sporadic breast and ovarian cancers. In human breast tumors, we have previously shown that AKT1 represses homologous recombination (HR) induced by one double-strand break (DSB). To further analyze the impact of AKT1 on HR, we ectopically expressed wild-type or mutant forms of AKT1 in a hamster ovary cell line containing an intrachromosomal substrate for monitoring HR. In this cell line, AKT1 repressed HR induced by different genotoxic stresses including ionizing radiation, UV-C and one single DSB introduced into the intrachromosomal substrate. Consistently, AKT1 disrupted RAD51 foci formation, showing that AKT1 specifically affects gene conversion. Concomitantly, AKT1 represses both BRCA1 foci formation and HR stimulation resulting from BRCA1 overexpression, showing that AKT1 affects BRCA1-mediated HR functions, also in another species (hamster) and in another type of cell tissue (ovary cells). Finally, consistent with the HR defects, active AKT1 expression induces supernumerary centrosomes and aneuploidy. In addition to its impact on cell proliferation and apoptosis, the present data propose a novel oncogenic function for AKT1, by producing genomic instability as a consequence of HR repression.

The prevalence of erectile dysfunction in heart failure patients by race and ethnicity

Erectile dysfunction (ED) is a common problem in male patients with heart failure (HF). However, no study was found that estimates the prevalence of ED by US ethnic groups with HF. We conducted an observational, cross-sectional study of patients enrolled in a HF disease management program in two sites Louisiana (N=329; 178 white, 99 black) and Florida (N=52; Hispanic). All male patients with an ejection fraction <or=40% were included. The Sexual Health Inventory for Men was used to estimate the prevalence of ED. Overall prevalence of ED was 89% and ED severity did not vary by race/ethnic group. Race/ethnic group differences were found for age, New York Heart Association functional classification, and blood pressure. Hispanic patients had the lowest unadjusted and adjusted prevalence rate of ED (81, 85%) compared to Black (90, 95%) and White (91, 92%) patients. There is a high prevalence of ED in Hispanic, Black and White ethnic groups with HF.

2-Methoxyestradiol attenuates hypertension and coronary vascular remodeling in spontaneously hypertensive rats

OBJECTIVES

Accumulating data provide evidence that some metabolites of 17beta-estradiol are biologically active and mediate multiple effects on the cardiovascular and renal systems. We investigated the effect of 2-methoxyestradiol (an active metabolite of estradiol with non-feminizing activity) on the development of hypertension and myocardial vascular remodeling in male and female ovarectomized SHR.

METHODS

Rats were divided into five groups: intact females, ovarectomized (OVX), OVX+ 2-methoxyestradiol (2ME), control males, and male+2ME. Systolic blood pressure was determined from 10 to 18 weeks. Structural changes in coronary vessels were quantified by an image analyzer. Immunoblotting of phosphorylated ERK1/2 and NADPH oxidase activity were performed on mesenteric arteries.

RESULTS

Treatment with 2ME reduced the increase in systolic blood pressure in male and ovarectomized rats to values not different from those obtained in intact females. Myocardial arterioles and small arteries showed significant increases in wall-to-lumen ratio and perivascular fibrosis in male and ovarectomized rats when compared with intact females. NADPH oxidase activity was increased in mesenteric arteries from males and ovarectomized females as compared with intact females. Finally, the expression of phosphorilated ERK1/2 were significantly higher in mesenteric arteries from male and ovariectomized animals than in those from intact females. Those effects of ovarectomy and gender differences were totally or partially prevented by treatment with 2-methoxyestradiol.

CONCLUSIONS

These data demonstrate that 2-methoxyestradiol protects the vasculature from hypertension-induced myocardial arterial remodeling in male and ovarectomized SHR, and that might be in part related to decreased superoxide generation and ERK1/2 activation.

In-vacuum optical isolation changes by heating in a Faraday isolator

We describe a model evaluating changes in the optical isolation of a Faraday isolator when passing from air to vacuum in terms of different thermal effects in the crystal. The changes are particularly significant in the crystal thermal lensing (refraction index and thermal expansion) and in its Verdet constant and can be ascribed to the less efficient convection cooling of the magneto-optic crystal of the Faraday isolator. An isolation decrease by a factor of 10 is experimentally observed in a Faraday isolator that is used in a gravitational wave experiment (Virgo) with a 10 W input laser when going from air to vacuum. A finite element model simulation reproduces with a great accuracy the experimental data measured on Virgo and on a test bench. A first set of measurements of the thermal lensing has been used to characterize the losses of the crystal, which depend on the sample. The isolation factor measured on Virgo confirms the simulation model and the absorption losses of 0.0016 +/- 0.0002/cm for the TGG magneto-optic crystal used in the Faraday isolator.

Targeted gene correction with 5' acridine-oligonucleotide conjugates

Single-stranded oligonucleotides (SSOs) mediate gene repair of punctual chromosomal mutations at a low frequency. We hypothesized that enhancement of DNA binding affinity of SSOs by intercalating agents may increase the number of corrected cells. Several biochemical modifications of SSOs were tested for their capability to correct a chromosomally integrated and mutated GFP reporter gene in human 293 cells. SSOs of 25 nucleotide length conjugated with acridine at their 5' end increased the efficiency of gene correction up to 10-fold compared to nonmodified SSOs. Acridine and psoralen conjugates were both evaluated, and acridine-modified SSOs were the most effective. Conjugation with acridine at the 3' end of the SSO inhibited gene correction, whereas flanking the SSO by acridine on both sides provided an intermediate level of correction. These results suggest that increasing the stability of hybridization between SSO and its target without hampering a 3' extension improves gene targeting, in agreement with the "annealing-integration" model of DNA repair.

Measurement of the optical parameters of the Virgo interferometer

The Virgo interferometer, aimed at detecting gravitational waves, is now in a commissioning phase. Measurements of its optical properties are needed for the understanding of the instrument. We present the techniques developed for the measurement of the optical parameters of Virgo. These parameters are compared with the Virgo specifications.

Uterine blood flow during supine rest and exercise after 28 weeks of gestation

OBJECTIVE

To test the null hypothesis that, after 28 weeks of gestation, uterine blood flow during supine rest and supine exercise is no different than uterine blood flow at left-lateral rest.

DESIGN

In vivo experimental study in pregnant women.

SETTING

Department of Obstetrics, MetroHealth Medical Center, Cleveland, OH, USA.

POPULATION

Fourteen, physically active, late-pregnant women who continued supine exercise throughout gestation.

METHODS

Studies were carried out between 29 and 38 weeks of gestation. Maternal blood pressure, maternal heart rate, and ultrasound estimates of volume blood flow in the right ascending branch of the uterine artery were obtained serially at rest in the left-lateral position, at rest in the supine position, during and immediately after 10 minutes of supine exercise, and again at rest in the left-lateral position. Exercise sessions included alternating 60- to 90-second periods of abdominal crunches and leg exercise at moderate/high intensity (Borg's rating of perceived exertion 14 +/- 1).

MAIN OUTCOME MEASURES

Blood pressure, heart rate, and uterine artery volume flow.

RESULTS

Data are presented as the mean +/- SD. Maternal heart rate and blood pressure were unchanged at supine rest but increased during supine exercise (heart rate increased from 76 +/- 9 to 98 +/- 12 beats per minute, mean arterial pressure increased from 81 +/- 6 to 102 +/- 12 mmHg). Volume flow fell from 410 +/- 93 to 267 +/- 73 cc/minute after 5 minutes of supine rest and then, during supine exercise, increased to 355 +/- 125 cc/minute. Uterine artery luminal diameter and blood flow correlated directly with tissue weights at birth (r(2) values between 0.32 and 0.59).

CONCLUSIONS

In physically active women, uterine blood flow decreases during both supine rest and supine exercise but the decrease in the former is twice that seen in the latter.

Outcome and morbidity of pancreas transplantation in a single Spanish institution

BACKGROUND

Pancreas transplantation is nowadays the only treatment to reestablish normal blood glucose in diabetic patients. Moreover, transplantation may also prevent and possibly even revert diabetes-related complications. We present our results with the first 4 years of a pancreas transplantation program.

MATERIALS AND METHODS

From February 2000 to June 2004, we performed 43 pancreas transplants in 42 recipients. In all cases the technique was enteric drainage of the exocrine secretions and systemic venous derivation to the inferior vena cava for endocrine secretions.

RESULTS

A simultaneous pancreas-kidney transplant was performed in 37 (88.1%) patients, a pancreas after kidney in 4 (9.5%) patients, and a retransplant in 1 (2.4%) patient. Glycosylated hemoglobin and C peptide returned to normal values in all cases. Patient and graft survivals were 91% and 84%, respectively, after a median follow-up of 19 months. The rate of reoperations was 31% with an overall 16% graft loss.

CONCLUSIONS

Our results were comparable to those of larger series.

Isolation, Tissue Distribution, and Molecular Characterization of Toxoplasma gondii From Free-Range Chickens From Guatemala

The prevalence of Toxoplasma gondii in free-ranging chickens is a good indicator of the prevalence of T. gondii oocysts in the soil because chickens feed from the ground. The prevalence of T. gondii in 50 free-range chickens (Gallus domesticus) from Guatemala was determined. Antibodies to T. gondii were assayed by the modified agglutination test (MAT). Antibodies were found in 37 (74%) chickens with titers of 1:5 (11), 1:10 (7), 1:20 (11), 1:40 (1), 1:80 (1), 1:160 (3), 1:1,280 (2), and 1:2,560 (1). Hearts, pectoral muscles, and brains of 19 chickens with MAT titers of 1:20 or more were bioassayed individually in mice. Tissues from the remaining 31 chickens with titers of 1:10 or lower were pooled and fed to 4 T. gondii-free cats (13 chickens with titers of less than 1:5 to 1 cat, 11 chickens with titers of 1:5 to 2 cats, and 7 chickens with titers of 1:10 to 1 cat). Feces of cats were examined for oocysts; they did not shed oocysts. Toxoplasma gondii was isolated from 8 chickens with MAT titers of 1:20 or more (from 1 of 11 chickens with a titer of 1:20 and all 7 chickens with a titer of 1:80 or more) from the heart, brain, and pectoral muscle (3); heart and pectoral muscle (1); and heart alone (4). Genotyping of these 8 isolates with the SAG2 locus indicated that 5 were type III and 3 were type 1. This is the first report of isolation of T. gondii from chickens from Guatemala.

Improving gene replacement by intracellular formation of linear homologous DNA

BACKGROUND

Gene targeting is a potential tool for gene therapy but is limited by the low rate of homologous recombination. Using highly homologous linear DNA improves gene targeting frequency but requires microinjection into nuclear cells to be effective. Because transfection of circular DNA is more efficient than transfection of linear DNA and adaptable to viral vectors, we developed a system for the intracellular release of linear fragments from circular plasmids.

METHODS

Only one cutting site inside the "donor" DNA was not convenient because it led to integration of exogenous sequences into the target. So we constructed several "donor" plasmids containing the homologous sequences flanked by two I-Sce I recognition sites. Expression of I-Sce I allowed intracellular delivery of "ends-out" (replacement) vectors. We compared the efficiency of different constructions to correct a mutated gfp target.

RESULTS

Co-transfection of "donor" plasmids and an I-Sce I expression vector into CHO cells enhanced the correction of an extrachromosomal mutated gfp target by at least 10 times. Maximum correction was observed with the greatest homology size and maximum effect of I-Sce I was obtained when the long hemi-sites of the duplicated I-Sce I sites were contiguous to the homologous sequence. Unexpectedly, the reverse orientation of I-Sce I sites provided little or no effect, probably due to the asymmetrical activity of the I-Sce I meganuclease.

CONCLUSIONS

Releasing homologous DNA fragments with I-Sce I enhances gene replacement. This work provides the basis for the future design of viral vectors for gene replacement.

The building blocks of planets within the 'terrestrial' region of protoplanetary disks

Our Solar System was formed from a cloud of gas and dust. Most of the dust mass is contained in amorphous silicates, yet crystalline silicates are abundant throughout the Solar System, reflecting the thermal and chemical alteration of solids during planet formation. (Even primitive bodies such as comets contain crystalline silicates.) Little is known about the evolution of the dust that forms Earth-like planets. Here we report spatially resolved detections and compositional analyses of these building blocks in the innermost two astronomical units of three proto-planetary disks. We find the dust in these regions to be highly crystallized, more so than any other dust observed in young stars until now. In addition, the outer region of one star has equal amounts of pyroxene and olivine, whereas the inner regions are dominated by olivine. The spectral shape of the inner-disk spectra shows surprising similarity with Solar System comets. Radial-mixing models naturally explain this resemblance as well as the gradient in chemical composition. Our observations imply that silicates crystallize before any terrestrial planets are formed, consistent with the composition of meteorites in the Solar System.

Enzymatic and electrochemical oxidation of N-hydroxy compounds. Redox potential, electron-transfer kinetics, and radical stability

A series of N-hydroxyacetanilide and 1-hydroxybenzotriazole analogues derivatized by various functional substituents were studied with regard to redox potential, oxidation by laccase, oxidative stability, and correlation to the electronic and steric properties of the substituents. It was found that substituents carrying conjugative/pi-electron function influenced the redox potential more than substituents carrying inductive/sigma-electron function, and that the electron-transfer from an N-hydroxy moiety to laccase was significantly affected by the redox potential. Electron-withdrawing substituents tended to reduce the electron density on the N-hydroxy group, leading to higher redox potential and lower oxidation rate. Bulky substitution or absence of N-phenyl tended to increase the Km of the N-hydroxy group, leading to lower oxidation rate. Oxidized N-hydroxy compounds were stabilized by N-phenyl or N-carbonyl group, but not by N-azo or highly strained structure. Potential implication of these effects on laccase-based, N-hydroxy compound-mediated biocatalysis is discussed.