Incubation of rat aortic rings produces a specific reduction in agonist-evoked contraction: effect of age of donor

We studied the effect of age on the response of aortic rings to injury produced by three days' incubation, and the mechanism of this response. Five-mm rings of the thoracic aorta isolated from Wistar rats were incubated or not in culture medium. Isometric contraction evoked by agonists (norepinephrine or serotonin) or high [K(+)](e) was determined in the presence and absence of endothelium. Experiments were repeated in the presence of propranolol (0.3 microM), polymixin B (36 microM), pyrrolidine dithiocarbamate (50 microM) or glutathione (3 mM). Inductible NO-synthase and cyclo-oxygenase-2 mRNA were determined by real-time PCR, and glutathione-related enzymes and catalase activity by spectrophotometry. Incubation reduced the isometric contraction evoked by agonists but not by high [K(+)](e). The reduction in agonist-evoked contraction was greater in rings from adult (norepinephrine Emax-80%) than in young (-40%) rats. The removal of the endothelium had no effect. The reduction in norepinephrine-evoked contraction was not due to endotoxin contamination, beta-adrenoceptor-mediated dilation or any change in ring structure (no fibrosis or edema). Inductible NO-synthase (but not cyclo-oxygenase-2) mRNA increased on incubation. N(G)-nitro-L-arginine methyl ester partially restored contractility in rings from adult animals, further addition of an anti-oxidant restored norepinephrine-evoked contraction. Catalase fell with age and glutathione reductase increased upon incubation in rings from young donors only. In conclusion, incubation of the aorta produces a specific reduction in agonist-evoked contraction that involves induction of smooth muscle cell oxidative stress and iNOS. The reaction is greater in rings from older animals.     

Identification of paraoxonase 3 gene (PON3) missense mutations in a population of southern Italy

PON gene family includes at least three members termed PON1, PON2 and PON3, and it is mapped on human chromosome 7q21-q22. PON1 and PON3 gene products are constituents of high density lipoprotein (HDL) and have many enzymatic properties and antioxidant activity. PONs are proposed to participate in the prevention of low density lipoprotein (LDL) oxidation. PON1 and PON2 genes have missense polymorphisms, but, to date, no missense variants are reported in PON3 gene. In this work we explored the existence of genetic variants within the PON3 coding sequences. Five point mutations were identified by direct sequencing of genomic DNA derived from 250 randomly selected DNA samples of 1143 blood donors living in southern Italy. Three were silent mutations, while two were missense mutations that give rise to amino acid substitutions at positions 311 (S>T) and 324 (G>D). The missense variations in the DNA of the 1143 samples had frequencies of 0.22% (5 out of 2286 alleles) for the S311T mutation, and 0.57% (13 out of 2286 alleles) for the G324D mutation. The effect of these variants on the metabolic activity of paraoxonase 3 remains to be further evaluated.     

The chromatin assembly factor subunit FASCIATA1 is involved in homologous recombination in plants

DNA replication in cycling eukaryotic cells necessitates the reestablishment of chromatin after nucleosome redistribution from the parental to the two daughter DNA strands. Chromatin assembly factor 1 (CAF-1), a heterotrimeric complex consisting of three subunits (p150/p60/p48), is one of the replication-coupled assembly factors involved in the reconstitution of S-phase chromatin. CAF-1 is required in vitro for nucleosome assembly onto newly replicated chromatin in human cells and Arabidopsis thaliana, and defects in yeast (Saccharomyces cerevisiae) affect DNA damage repair processes, predominantly those involved in genome stability. However, in vivo chromatin defects of caf-1 mutants in higher eukaryotes are poorly characterized. Here, we show that fasciata1-4 (fas1-4), a new allele of the Arabidopsis fas1 mutant defective in the p150 subunit of CAF-1, has a severe developmental phenotype, reduced heterochromatin content, and a more open conformation of euchromatin. Most importantly, homologous recombination (HR), a process involved in maintaining genome stability, is increased dramatically in fas1-4, as indicated by a 96-fold stimulation of intrachromosomal HR. Together with the open conformation of chromatin and the nearly normal expression levels of HR genes in the mutant, this result suggests that chromatin is a major factor restricting HR in plants.     

Teaching aldosterone regulation and basic scientific principles using a classic paper by Dr. James O. Davis and colleagues

Classroom discussion of scientific articles can be an effective means of teaching scientific principles and methodology to both undergraduate and graduate science students. The availability of classic papers from the American Physiological Society Legacy Project has made it possible to access articles dating back to the early portions of the 20th century. In this article, we discuss a classic paper from the laboratory of Dr. James O. Davis on the regulation of aldosterone synthesis from the adrenal zona glomerulosa cell. Dr. Davis has conducted much of the seminal research investigating the renin-angiotensin system and the regulation of aldosterone release by angiotensin II. In addition to a characterization of the effects of ACTH on aldosterone regulation, this study is useful for discussing the basic principles of negative feedback pathways of the hypothalamic-pituitary axis. This study also provides examples of early bioassay techniques for the detection of angiotensin II and of the importance of quantitative measurements when investigating physiological responses. Three figures and one table are reproduced from the original article along with a series of discussion questions designed to facilitate discovery learning.     

Chloroplast DNA variation and population structure in the widespread forest tree, Eucalyptus grandis

Recognition of genetic structure of populations and the ability to identify vulnerable populations is useful for the formation of conservation management strategies for plants. Eucalyptus grandis is a tall forest tree that has a major area of occurrence in subtropical eastern Australia, with smaller populations located in the east coast tropics. Many widespread forest species exhibit population differentiation that corresponds to geographic regions. However, Eucalyptus grandis appears to be an exception based on isozyme and morphological data. This is intriguing given a large discontinuity between northern populations and those in the southern part of the species range. In this study, the distribution of a maternally inherited chloroplast locus was examined because it was more likely to reveal genetic structure due to the slower evolution of the chloroplast genome and limited dispersal of seed in eucalypts. As expected, the G _ST for chloroplast DNA was higher than that for nuclear DNA but indicated low population differentiation for a forest tree species. Phylogeographic analysis indicated that the 15 populations grouped into three broad geographical regions; however, overall population structure was weak suggesting that the large geographical disjunction in the distribution of E. grandis may be relatively recent. A paradigm for conservation management of E. grandis based on chloroplast DNA haplotype distribution would take into account the low differentiation among populations.     

Body image and quality of life in post massive weight loss body contouring patients

Objective: Because post‐bariatric surgery patients undergo massive weight loss, the resulting skin excess can lead to both functional problems and profound dissatisfaction with appearance. Correcting skin excess could improve all these corollaries, including body image. Presently, few data are available documenting body image and weight‐related quality of life in this population. Research Methods and Procedures: Eighteen patients who underwent both bariatric surgery and body contouring completed our study. Both established surveys and new surveys designed specifically for the study were used to assess body perception and ideals, quality of life, and mood. Patients were surveyed at the following time‐points: pre‐body contouring (after massive weight loss) and both 3 and 6 month post‐body contouring. Statistical testing was performed using Student's t test and ANOVA. Results: The mean age of the patients was 46 ± 10 years (standard deviation). Quality of life improved after obesity surgery and was significantly enhanced after body contouring. Three months after body contouring, subjects ascribed thinner silhouettes to both current appearance and ideal body image. Body image also improved with body contouring surgery. Mood remained stable over 6 months. Discussion: Body contouring after surgical weight loss improved both quality‐of‐life measurements and body image. Initial body dissatisfaction did not correlate with mood. Body contouring improved body image but produced dissatisfaction with other parts of the body, suggesting that as patients become closer to their ideal, these ideals may shift. We further developed several new assessment methods that may prove useful in understanding these post‐surgical weight loss patients.     

Clinician reviewers in birth defects surveillance programs: survey of the National Birth Defects Prevention Network

BACKGROUND: Some birth defects surveillance programs utilize a clinician reviewer ("Clinician") to assist the multidisciplinary staff in the process of case review, coding and classification. The untested assumption is that expertise in the evaluation of individuals with birth defects and genetic syndromes in clinical practice, usually clinical genetics, is useful in reviewing medical records. METHODS: We conducted an exploratory survey of the 50 functioning birth defects surveillance programs that participated in the National Birth Defects Prevention Network in 2004. The survey was mailed electronically to program coordinators and included 10 questions with check-off option replies. Open-ended comments were also solicited. RESULTS: Responses were received from 31 of 50 (62%) programs, 21 (68%) which used a Clinician. In addition to the 9 centers that identified themselves as participants in the National Birth Defects Prevention Study (NBDPS), there were 12 non-NBDPS programs using a Clinician, 2 of whom were not clinical geneticists (1 nurse genetic counselor and 1 primary pediatrician). A total of 86% (18/21) of Clinicians were employed part-time or as consultants; 1 was full-time, and 2 were volunteers. In addition to the core activities of classifying defects and reviewing cases to determine if a syndrome was present, over one-half of the Clinicians participated in education of birth defects surveillance programs staff, research, and program development. Most (86%; 18/21) Clinicians had been trained informally for their roles. Only 1 had received a formal performance review. CONCLUSIONS: Aside from the 9 centers in the NBDPS in which the position of Clinician is funded by the Centers for Disease Control and Prevention (CDC), about one-half of the remaining respondent birth defects surveillance programs used a Clinician. Future research is needed to determine why a birth defects surveillance program hires or refrains from using a Clinician, and whether a Clinician accomplishes the desired goals. This survey reveals a lack of formal training for the Clinicians in their roles in the surveillance programs, and a lack of quality monitors, which might be addressed in the future.     

Galanin and its binding sites in the brain of eels subjected to different osmolar conditions

A galanin (GAL)-like peptidergic system was investigated in the brain of Anguilla anguilla subjected to hyperosmolar and hypoosmolar conditions, by using antisera raised against porcine 1-29 GAL. A group of immunoreactive perikaria was identified in the periventricular hypothalamus, in the ventral thalamus, in the pretectal areas and in the optic tectum. Immunoreactive perikaria were present in the nucleus lateralis of the torus semicircularis in seawater (SW) adapted eels, and were absent in the freshwater (FW) adapted eels. Galaninergic fibres were observed in many areas of the brain. The immunoreactive perikaria and fibres, when localised in the same areas, were more strongly labelled and numerous in the SW adapted eels in comparison to the FW adapted animals. GAL-specific binding sites, investigated by autoradiography using iodinated porcine GAL, occurred in several regions of the brain, in particular in the dorsal telencephalon, in the dorsal thalamus and in the torus semicircularis, where a high density of binding sites was observed in the SW adapted eels. Conversely, a higher density of binding sites was observed in the caudal substantia reticularis and in the corpus cerebelli in the FW adapted eels. We conclude that different distributions and intensity in immunoreactive elements occur in response to the two environmental conditions.