Concept Development In Relation To The Biology Of Reproduction In Secondary Science : A Vygotskyan Perspective

The study of concept development in biology comes from a professional concern that arose in my classroom teaching - an inability, after many years practice of the techniques of ‘discovery science’, to accept the theoretical base of the individual secondary school pupil constructing science concepts mainly through experiment. From this concern arose my research question - the extent to which a developmental space could be defined in which the development of science concepts could take place. The instance for examining such a space would be science concepts of reproduction. To develop a model for such a space I looked at the work of Jean Piaget, Lev Vygotsky and a number of other theorists concerned with the issue of innate learning mechanisms and of constructivism and social constructivism. I adopted Vygotsky’s dialectical materialist approach in assessing the concepts involved. To test the emerging model I decided on a case study approach, defined in terms of both the case as instance and the case as issue - instance in that the focus would be a year 8 (Britain year 7) science class, with interviews across the year group The study would involve the case as issue in that I intended to walk through the process of concept formation in plant and human reproduction with the pupils. I applied a mixture of semi-structured interview and classroom observation, linked through the development of ‘structured situations’ in which models and materials were made available in specific social settings in the expectation that the pupils would construct meaning. The outcome of the investigation did not support the initial model, but it did suggest in outline a new model of a developmental space. This suggested that the different goals of teacher and pupils expressed themselves as implicit and explicit elements of the situation, often resolved by the pupils completing tasks without thought. This indicated that a common outcome of schooling was ‘encapsulation’, formal mental constructs lacking meaning. Elements of a new model would be the role of emotion and of the goal of activity

Report from the MPP Working Group to the NASA Associate Administrator for Space Science and Applications

NASA's Office of Space Science and Applications (OSSA) gave a select group of scientists the opportunity to test and implement their computational algorithms on the Massively Parallel Processor (MPP) located at Goddard Space Flight Center, beginning in late 1985. One year later, the Working Group presented its report, which addressed the following: algorithms, programming languages, architecture, programming environments, the way theory relates, and performance measured. The findings point to a number of demonstrated computational techniques for which the MPP architecture is ideally suited. For example, besides executing much faster on the MPP than on conventional computers, systolic VLSI simulation (where distances are short), lattice simulation, neural network simulation, and image problems were found to be easier to program on the MPP's architecture than on a CYBER 205 or even a VAX. The report also makes technical recommendations covering all aspects of MPP use, and recommendations concerning the future of the MPP and machines based on similar architectures, expansion of the Working Group, and study of the role of future parallel processors for space station, EOS, and the Great Observatories era

Original Research Oral Quercetin Supplementation and Blood Oxidative Capacity in Response to Ultramarathon Competition

Previous research indicates that ultramarathon exercise can result in blood oxidative stress. The purpose of this investigation was to examine the efficacy of oral supplementation with quercetin, a naturally occurring compound with known antioxidant properties, as a potential countermeasure against blood oxidative stress during an ultramarathon competition. In double-blind fashion, 63 participants received either oral quercetin (250 mg, 4×/day; 1,000 mg/day total) or quercetin-free supplements 3 weeks before and during the 160-km Western States Endurance Run. Blood drawn before and immediately after (quercetin finishers n = 18, quercetin-free finishers n = 21) the event was analyzed for changes in blood redox status and oxidative damage. Results show that quercetin supplementation did not affect race performance. In response to the ultramarathon challenge, aqueous-phase antioxidant capacity (ferric-reducing ability of plasma) was similarly elevated in athletes in both quercetin and quercetin-free treatments and likely reflects significant increases in plasma urate levels. Alternatively, trolox-equivalent antioxidant capacity was not altered by exercise or quercetin. Accordingly, neither F2-isoprostances nor protein carbonyls were influenced by either exercise or quercetin supplementation. In the absence of postrace blood oxidative damage, these findings suggest that oral quercetin supplementation does not alter blood plasma lipid or aqueous-phase antioxidant capacity or oxidative damage during an ultramarathon challenge

Successive Bouts of Cycling Stimulates Genes Associated with Mitochondrial Biogenesis

Exercise increases mRNA for genes involved in mitochondrial biogenesis and oxidative enzyme capacity. However, little is known about how these genes respond to consecutive bouts of prolonged exercise. We examined the effects of 3 h of intensive cycling performed on three consecutive days on the mRNA associated with mitochondrial biogenesis in trained human subjects. Forty trained cyclists were tested for VO2max (54.7 ± 1.1 ml kg−1 min−1). The subjects cycled at 57% wattsmax for 3 h using their own bicycles on CompuTrainer™ Pro Model trainers (RacerMate, Seattle, WA) on three consecutive days. Muscle biopsies were obtained from the vastus lateralis pre- and post-exercise on days one and three. Muscle samples were analyzed for mRNA content of peroxisome proliferator receptor gamma coactivator-1 alpha (PGC-1α), sirtuin 1 (Sirt-1), cytochrome c, and citrate synthase. Data were analyzed using a 2 (time) × 2 (day) repeated measures ANOVA. Of the mRNA analyzed, the following increased from pre to post 3 h rides: cytochrome c (P = 0.006), citrate synthase (P = 0.03), PGC-1α (P \u3c 0.001), and Sirt-1 (P = 0.005). The following mRNA showed significant effects from days one to three: cytochrome c (P \u3c 0.001) and citrate synthase (P = 0.01). These data show that exhaustive cycling performed on three consecutive days resulted in both acute and chronic stimuli for mRNA associated with mitochondrial biogenesis in already trained subjects. This is the first study to illustrate an increase in sirtuin-1 mRNA with acute and chronic exercise. These data contribute to the understanding of mRNA expression during both acute and successive bouts of prolonged exercise

Genetic partitioning of interleukin-6 signalling in mice dissociates Stat3 from Smad3-mediated lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disease that is unresponsive to current therapies and characterized by excessive collagen deposition and subsequent fibrosis. While inflammatory cytokines, including interleukin (IL)-6, are elevated in IPF, the molecular mechanisms that underlie this disease are incompletely understood, although the development of fibrosis is believed to depend on canonical transforming growth factor (TGF)-β signalling. We examined bleomycin-induced inflammation and fibrosis in mice carrying a mutation in the shared IL-6 family receptor gp130. Using genetic complementation, we directly correlate the extent of IL-6-mediated, excessive Stat3 activity with inflammatory infiltrates in the lung and the severity of fibrosis in corresponding gp130757F mice. The extent of fibrosis was attenuated in B lymphocyte-deficient gp130757F;µMT−/− compound mutant mice, but fibrosis still occurred in their Smad3−/− counterparts consistent with the capacity of excessive Stat3 activity to induce collagen 1α1 gene transcription independently of canonical TGF-β/Smad3 signalling. These findings are of therapeutic relevance, since we confirmed abundant STAT3 activation in fibrotic lungs from IPF patients and showed that genetic reduction of Stat3 protected mice from bleomycin-induced lung fibrosis

Quercetin Ingestion Does Not Alter Cytokine Changes in Athletes Competing in the Western States Endurance Run

The purpose of this study was to measure the influence of quercetin on plasma cytokines, leukocyte cytokine mRNA, and related variables in ultramarathoners competing in the 160-km Western States Endurance Run (WSER). Sixty-three runners were randomized to quercetin and placebo groups and under double-blinded methods ingested 1000 mg/day quercetin for 3 weeks before the WSER. Thirty-nine of the 63 subjects (n = 18 for quercetin, n = 21 for placebo) finished the race and provided blood samples the morning before the race and 15–30 min postrace. Significant prerace to postrace WSER increases were measured for nine proinflammatory and anti-inflammatory plasma cytokines, cortisol (quercetin = 94%, placebo = 96%), serum C-reactive protein (CRP) (mean ± SE absolute increase, quercetin = 31.8 ± 4.2, placebo = 38.2 ± 5.0 mg/L), and creatine kinase (CK) (quercetin = 21,575 ± 3,977, placebo = 19,455 ± 3,969 U/L), with no significant group differences. Interleukin-6 (IL-6) mRNA did not change post-WSER, with a significant decrease measured for leukocyte IL-8 mRNA (0.21 ± 0.03-fold and 0.25 ± 0.04-fold change from rest, quercetin and placebo, respectively) and significant increases for IL-1Ra mRNA (1.43 ± 0.18-fold and 1.40 ± 0.16-fold change, quercetin and placebo, respectively) and IL-10 mRNA (12.9 ± 3.9-fold and 17.2 ± 6.1-fold change, quercetin and placebo, respectively), with no significant differences between groups. In conclusion, quercetin ingestion (1 g/day) by ultramarathon athletes for 3 weeks before a competitive 160-km race significantly increased plasma quercetin levels but failed to attenuate muscle damage, inflammation, increases in plasma cytokine and hormone levels, and alterations in leukocyte cytokine mRNA expression

Shigellosis Linked to Sex Venues, Australia

From January 1 to July 31, 2000, 148 cases of Shigella infection were reported in New South Wales, Australia, compared with an annual average of 95 cases. Of reported cases, 83% were confirmed as Shigella sonnei biotype G infections; 80% were in homosexual men. Visiting a sex venue in the 2 weeks before onset of illness was the only factor significantly associated with shigellosis

Genetic partitioning of interleukin-6 signalling in mice dissociates Stat3 from Smad3-mediated lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a fatal disease that is unresponsive to current therapies and characterized by excessive collagen deposition and subsequent fibrosis. While inflammatory cytokines, including interleukin (IL)-6, are elevated in IPF, the molecular mechanisms that underlie this disease are incompletely understood, although the development of fibrosis is believed to depend on canonical transforming growth factor (TGF)-beta signalling. We examined bleomycin-induced inflammation and fibrosis in mice carrying a mutation in the shared IL-6 family receptor gp130. Using genetic complementation, we directly correlate the extent of IL-6-mediated, excessive Stat3 activity with inflammatory infiltrates in the lung and the severity of fibrosis in corresponding gp130757F mice. The extent of fibrosis was attenuated in B lymphocyte-deficient gp130757F;mu MT-/- compound mutant mice, but fibrosis still occurred in their Smad3-/- counterparts consistent with the capacity of excessive Stat3 activity to induce collagen 1a1 gene transcription independently of canonical TGF-beta/Smad3 signalling. These findings are of therapeutic relevance, since we confirmed abundant STAT3 activation in fibrotic lungs from IPF patients and showed that genetic reduction of Stat3 protected mice from bleomycin-induced lung fibrosis

Ventricular pacing or dual-chamber pacing for sinus-node dysfunction

BACKGROUND Dual-chamber (atrioventricular) and single-chamber (ventricular) pacing are alternative treatment approaches for sinus-node dysfunction that causes clinically significant bradycardia. However, it is unknown which type of pacing results in the better outcome. METHODS We randomly assigned a total of 2010 patients with sinus-node dysfunction to dual-chamber pacing (1014 patients) or ventricular pacing (996 patients) and followed them for a median of 33.1 months. The primary end point was death from any cause or nonfatal stroke. Secondary end points included the composite of death, stroke, or hospitalization for heart failure; atrial fibrillation; heart-failure score; the pacemaker syndrome; and the quality of life. RESULTS The incidence of the primary end point did not differ significantly between the dual-chamber group (21.5 percent) and the ventricular-paced group (23.0 percent, P=0.48). In patients assigned to dual-chamber pacing, the risk of atrial fibrillation was lower (hazard ratio, 0.79; 95 percent confidence interval, 0.66 to 0.94; P=0.008), and heart-failure scores were better (P CONCLUSIONS In sinus-node dysfunction, dual-chamber pacing does not improve stroke-free survival, as compared with ventricular pacing. However, dual-chamber pacing reduces the risk of atrial fibrillation, reduces signs and symptoms of heart failure, and slightly improves the quality of life. Overall, dual-chamber pacing offers significant improvement as compared with ventricular pacing