Myocardial hypertrophy in rats exposed to simulated high altitude

Myocardial hypertrophy in Sprague-Dawley adult rats exposed to hypobaric hypoxia (0.40 atmosphere of air/18 h daily for 7 days) in a hypobaric chamber was investigated. Changes in the myocardial mass were evaluated on the basis of the dry heart weight and expressed as mg/100 g of total body weight (mean +/- SEM). Data are presented indicating that: chronic hypobaric hypoxia causes a significant degree of myocardial hypertrophy in rats; hypertrophic process involves both ventricles (the right more than the left); removal of the hypoxic stimulus leads to the disappearance of hypertrophy when evaluated as an increase in dry heart weight; hypoxia affects the synthesis of a significant amount of connective tissue in the left ventricle, which is not exposed to pressure load. The r?le of neurohumoral factors (i.e., adrenergic stimulation and catecholamines) in the development of the ventricular hypertrophy is suggested.     

Cloning, sequencing, and functional analysis of oriL, a herpes simplex virus type 1 origin of DNA synthesis.

The herpes simplex virus type 1 genome (160 kilobases) contains three origins of DNA synthesis: two copies of oriS located within the repeated sequences flanking the short unique arm (US), and one copy of oriL located within the long unique arm (UL). Precise localization and characterization of oriL have been severely hampered by the inability to clone sequences which contain it (coordinates 0.398 to 0.413) in an undeleted form in bacteria. We report herein the successful cloning of sequences between 0.398 to 0.413 in an undeleted form, using a yeast cloning vector. Sequence analysis of a 425-base pair fragment spanning the deletion-prone region has revealed a perfect 144-base pair palindrome with striking homology to oriS. In a functional assay, the undeleted clone was amplified when functions from herpes simplex virus type 1 were supplied in trans, whereas clones with deletions of 55 base pairs or more were not amplified.     

Effects of various compounds on growth of yeast cells of Histoplasma capsulatum

Summary A number of compounds were screened for their effects on growth of the yeast cells ofHistoplasma capsulatum. Included were penicillin and related compounds, sulfhydryl inhibitors, various organic sulfur compounds recently synthesized for the first time, and compounds structurally related to the required metabolites, thiamine and cystine or cysteine. Cephalothin was the only one of the penicillin related compounds which inhibited growth. This occurred only when a high concentration (8.3 × 10^–4 M) was used. Of the analogues of cystine tested, allylglycine had the greatest inhibitory effect on growth of the yeast cells in the synthetic medium, but it failed to inhibit growth in a complex medium containing peptones and plasma. Among the sulfhydryl inhibitors, the maleimides were the most effective, producing complete inhibition of growth in the peptone medium at 10µg/ml or less. At subinhibitory concentrations the cultures tended to become mycelial. The action of the maleimides was reversed by cystine over a range of concentrations. At low concentrations, some of the disulfide derivatives of thiamine stimulated growth equally as well as thiamine, but at concentrations of 100 to 150µg/ml, they completely inhibited growth. On the basis of results obtained to date, three classes of the new organic sulfur compounds being tested offer promise as sources of potentially useful chemotherapeutic agents. These classes, which differ widely in structure, are as follows: the benzyl decylaminoethyl disulfides, the acyl disulfides, and the trithiopercarbamates.This investigation was supported by Public Health Service Research Grant AI-03524 from the National Institute of Allergy and Infectious Diseases.     

Degradation of azo dyes by the lignin-degrading fungus Phanerochaete chrysosporium.

Under nitrogen-limiting, secondary metabolic conditions, the white rot basidiomycete Phanerochaete chrysosporium extensively mineralized the specifically 14C-ring-labeled azo dyes 4-phenylazophenol, 4-phenylazo-2-methoxyphenol, Disperse Yellow 3 [2-(4'-acetamidophenylazo)-4-methylphenol], 4-phenylazoaniline, N,N-dimethyl-4-phenylazoaniline, Disperse Orange 3 [4-(4'-nitrophenylazo)-aniline], and Solvent Yellow 14 (1-phenylazo-2-naphthol). Twelve days after addition to cultures, the dyes had been mineralized 23.1 to 48.1%. Aromatic rings with substituents such as hydroxyl, amino, acetamido, or nitro functions were mineralized to a greater extent than unsubstituted rings. Most of the dyes were degraded extensively only under nitrogen-limiting, ligninolytic conditions. However, 4-phenylazo-[U-14C]phenol and 4-phenylazo-[U-14C]2-methoxyphenol were mineralized to a lesser extent under nitrogen-sufficient, nonligninolytic conditions as well. These results suggest that P. chrysosporium has potential applications for the cleanup of textile mill effluents and for the bioremediation of dye-contaminated soil.     

Influence of rhizodeposition under elevated CO2 on plant nutrition and soil organic matter

Atmospheric CO₂ concentrations can influence ecosystem carbon storage through net primary production (NPP), soil carbon storage, or both. In assessing the potential for carbon storage in terrestrial ecosystems under elevated CO₂, both NPP and processing of soil organic matter (SOM), as well as the multiple links between them, must be examined. Within this context, both the quantity and quality of carbon flux from roots to soil are important, since roots produce specialized compounds that enhance nutrient acquisition (affecting NPP), and since the flux of organic compounds from roots to soil fuels soil microbial activity (affecting processing of SOM).From the perspective of root physiology, a technique is described which uses genetically engineered bacteria to detect the distribution and amount of flux of particular compounds from single roots to non-sterile soils. Other experiments from several labs are noted which explore effects of elevated CO₂ on root acid phosphatase, phosphomonoesterase, and citrate production, all associated with phosphorus nutrition. From a soil perspective, effects of elevated CO₂ on the processing of SOM developed under a C4 grassland but planted with C3 California grassland species were examined under low (unamended) and high (amended with 20 g m^–2 NPK) nutrients; measurements of soil atmosphere 13C combined with soil respiration rates show that during vegetative growth in February, elevated CO₂ decreased respiration of carbon from C4 SOM in high nutrient soils but not in unamended soils.This emphasis on the impacts of carbon loss from roots on both NPP and SOM processing will be essential to understanding terrestrial ecosystem carbon storage under changing atmospheric CO₂ concentrations.Abbreviations SOM soil organic matter - NPP net primary productivity - NEP net ecosystem productivity - PNPP p-nitrophenyl phosphate     

The Arabidopsis MALE STERILITY 2 protein shares similarity with reductases in elongation/condensation complexes

The Arabidopsis thaliana MALE STERILITY 2 ( MS2 ) gene product is involved in male gametogenesis. The first abnormalities in pollen development of ms2 mutants are seen at the stage in microsporogenesis when microspores are released from tetrads. Expression of the MS2 gene is observed in tapetum of wild-type flowers at, and shortly after, the release of microspores from tetrads. The MS2 promoter controls GUS expression at a comparable stage in the tapetum of transgenic tobacco containing an MS2 promoter–GUS fusion. The occasional pollen grains produced by mutant ms2 plants have very thin pollen walls. They are also sensitive to acetolysis treatment, which is a test for the presence of an exine layer. The MS2 gene product shows sequence similarity to a jojoba protein that converts wax fatty acids to fatty alcohols. A possible function of the MS2 protein as a fatty acyl reductase in the formation of pollen wall substances is discussed.     

Magnesium isotope fractionation during microbially enhanced forsterite dissolution

Bacillus subtilis endospore‐mediated forsterite dissolution experiments were performed to assess the effects of cell surface reactivity on Mg isotope fractionation during chemical weathering. Endospores present a unique opportunity to study the isolated impact of cell surface reactivity because they exhibit extremely low metabolic activity. In abiotic control assays, ²⁴Mg was preferentially released into solution during forsterite dissolution, producing an isotopically light liquid phase (δ²⁶Mg = ?0.39 ± 0.06 to ?0.26 ± 0.09‰) relative to the initial mineral composition (δ²⁶Mg = ?0.24 ± 0.03‰). The presence of endospores did not have an apparent effect on Mg isotope fractionation associated with the release of Mg from the solid into the aqueous phase. However, the endospore surfaces preferentially adsorbed ²⁴Mg from the dissolution products, which resulted in relatively heavy aqueous Mg isotope compositions. These aqueous Mg isotope compositions increased proportional to the fraction of dissolved Mg that was adsorbed, with the highest measured δ²⁶Mg (?0.08 ± 0.07‰) corresponding to the highest degree of adsorption (~76%). The Mg isotope composition of the adsorbed fraction was correspondingly light, at an average δ²⁶Mg of ?0.49‰. Secondary mineral precipitation and Mg adsorption onto secondary minerals had a minimal effect on Mg isotopes at these experimental conditions. Results demonstrate the isolated effects of cell surface reactivity on Mg isotope fractionation separate from other common biological processes, such as metabolism and organic acid production. With further study, Mg isotopes could be used to elucidate the role of the biosphere on Mg cycling in the environment.     

<Emphasis Type="Italic">CER1</Emphasis>gene variations associated with bone mineral density,bone markers,and early menopause in postmenopausal women

Background

Osteoporosis has a multifactorial pathogenesis characterized by a combination of low bone mass and increased fragility. In our study, we focused on the effects of polymorphisms in CER1 and DKK1 genes, recently reported as important susceptibility genes for osteoporosis, on bone mineral density (BMD) and bone markers in osteoporotic women. Our objective was to evaluate the effect of CER1 and DKK1 variations in 607 postmenopausal women. The entire DKK1 gene sequence and five selected CER1 SNPs were amplified and resequenced to assess whether there is a correlation between these genes and BMD, early menopause, and bone turnover markers in osteoporotic patients.

Results

Osteoporotic women seem to suffer menopause 2 years earlier than the control group. The entire DKK1 gene sequence analysis revealed six variations. There was no correlation between the six DKK1 variations and osteoporosis, in contrast to the five common CER1 variations that were significantly associated with BMD. Additionally, osteoporotic patients with rs3747532 and rs7022304 CER1 variations had significantly higher serum levels of parathyroid hormone and calcitonin and lower serum levels of osteocalcin and IGF-1.

Conclusions

No significant association between the studied DKK1 variations and osteoporosis was found, while CER1 variations seem to play a significant role in the determination of osteoporosis and a potential predictive role, combined with bone markers, in postmenopausal osteoporotic women.

     

Objective Measurement of Daytime Napping,Cognitive Dysfunction and Subjective Sleepiness in Parkinson’s Disease

Introduction

Sleep-wake disturbances and concomitant cognitive dysfunction in Parkinson’s disease (PD) contribute significantly to morbidity in patients and their carers. Subjectively reported daytime sleep disturbance is observed in over half of all patients with PD and has been linked to executive cognitive dysfunction. The current study used daytime actigraphy, a novel objective measure of napping and related this to neuropsychological performance in a sample of PD patients and healthy, age and gender-matched controls. Furthermore this study aimed to identify patients with PD who may benefit from pharmacologic and behavioural intervention to improve these symptoms.

Methods

Eighty-five PD patients and 21 healthy, age-matched controls completed 14 days of wrist actigraphy within two weeks of neuropsychological testing. Objective napping measures were derived from actigraphy using a standardised protocol and subjective daytime sleepiness was recorded by the previously validated Epworth Sleepiness Scale.

Results

Patients with PD had a 225% increase in the mean nap time per day (minutes) as recorded by actigraphy compared to age matched controls (39.2 ± 35.2 vs. 11.5 ± 11.0 minutes respectively, p < 0.001). Significantly, differences in napping duration between patients, as recorded by actigraphy were not distinguished by their ratings on the subjective measurement of excessive daytime sleepiness. Finally, those patients with excessive daytime napping showed greater cognitive deficits in the domains of attention, semantic verbal fluency and processing speed.

Conclusion

This study confirms increased levels of napping in PD, a finding that is concordant with subjective reports. However, subjective self-report measures of excessive daytime sleepiness do not robustly identify excessive napping in PD. Fronto-subcortical cognitive dysfunction was observed in those patients who napped excessively. Furthermore, this study suggests that daytime actigraphy, a non-invasive and inexpensive objective measure of daytime sleep, can identify patients with PD who may benefit from pharmacologic and behavioural interventions to improve these symptoms.