Does type 2 diabetes predispose to osteoporotic bone fractures?

Chronic complications of diabetes are associated mainly with changes in major and small arterial vessels as well as in peripheral and autonomic fibers of the nervous system. For years it has been suggested that DM2 does not predispose to osteoporosis because bone mineral density (BMD) in DM2 patients is commonly normal or even increased. However, results of recent large cross-sectional studies have indicated that patients with DM2 have significantly increased risk of bone fractures, predominantly hip fractures (by 70%). Results of these studies suggest that the increased risk of fractures in DM2 is independent of BMD. In this group of patients is frequently associated the loss of vision caused by diabetic eye disease, peripheral neuropathy, arterial hypertension, orthostatic hypotonia (caused by autonomic neuropathy or/and by concomitant antihypertensive treatment), and ischemic disease of the brain, heart and lower extremities--conditions that predispose to falls. There are no specific methods of prophylaxis and treatment of osteoporosis associated with diabetes; therefore they should be based on widely accepted principles as in non-diabetic populations. It seems that in DM2 patients the most purposeful strategy could be the popularization of healthy attitudes aiming the elimination of unfavorable dietetic and environmental factors, such as low physical activity, smoking, and low vitamin D intake, as well as education against falls.     

Does random blood glucose sampling outdate testing for glycosuria in the detection of diabetes during pregnancy?

A random blood glucose concentration was determined in 2403 pregnant women attending an antenatal clinic at between 28 and 32 weeks'' gestation. The calculated 99% cut off values were 6.1 mmol/l (110 mg/100 ml) within two hours after a meal and 5.6 mmol/l (101 mg/100 ml) more than two hours after a meal. Patients with a blood glucose concentration in excess of these values were referred for a 75 g oral glucose tolerance test. Of 59 referred, four were found to have previously unsuspected but unequivocal diabetes mellitus and another four to have impaired glucose tolerance on the basis of the World Health Organisation''s criteria. Screening all antenatal patients by randomly measuring blood glucose concentrations is not only cheap and efficient but also does not interfere with the routine of busy antenatal clinics.     

Is the origin of type 1 diabetes in the gut?

In type 1 diabetes, insulin-producing beta-cells in the pancreas are destroyed by immune-mediated mechanisms. The manifestation of the disease is preceded by the so-called pre-diabetic period that may last several years and is characterized by the appearance of circulating autoantibodies against beta-cell antigens. The role of the gut as a regulator of type 1 diabetes was suggested in animal studies, in which changes affecting the gut immune system modulated the incidence of diabetes. Dietary interventions, alterations in the intestinal microbiota and exposure to enteric pathogens, regulate the development of autoimmune diabetes in animal models. It has been demonstrated that these modulations affect the gut barrier mechanisms and intestinal immunity. Because the pancreas and the gut belong to the same intestinal immune system, the link between autoimmune diabetes and the gut is not unexpected. The gut hypothesis in the development of type 1 diabetes is also supported by the observations made in human type 1 diabetes. Early diet could modulate the development of beta-cell autoimmunity; weaning to hydrolysed casein formula decreased the risk of beta-cell autoimmunity by age 10 in the infants at genetic risk. Increased gut permeability, intestinal inflammation with impaired regulatory mechanisms and dysregulated oral tolerance have been observed in children with type 1 diabetes. The factors that contribute to these intestinal alterations are not known, but interest is focused on the microbial stimuli and function of innate immunity. It is likely that our microbial environment does not support the healthy maturation of the gut and tolerance in the gut, and this leads to the increasing type 1 diabetes as well as other immune-mediated diseases regulated by intestinal immune system. Thus, the interventions, aiming to prevent or treat type 1 diabetes in humans, should be targeting the gut immune system.     

Does domain swapping improve the stability of RNase A?

Self-assembling complexes have potential as novel supramolecular biomaterials but domain swapped complexes have yet to investigated in this capacity. Bovine ribonuclease A (RNase A) is a useful model protein as it is able to form a range of three dimensional domain swapped structures, including dimers, trimers and tetramers that have similar catalytic ability. However, little work has been carried out investigating the physical characteristics of these complexes. In an effort to characterise the strength of these oligomeric interactions, analytical ultracentrifugation was carried out to measure the dissociation of higher order complexes, using fluorescent tags to test for dissociation at very low concentrations. Results of this work suggest that the oligomers form a very tight complex, with no evidence of dissociation down to 250 pM. RNase A oligomers also had similar thermal stability to that of monomeric enzyme, suggesting that the main limiting factor in RNase A stability is the tertiary, rather than quaternary structure. Following thermal unfolding of RNase A, the protein refolded upon cooling, but returned to the monomeric state. This latter result may limit the potential of domain swapping as a means of material assembly.     

Does genetic introgression improve female reproductive performance? A test on the endangered Florida panther

Genetic introgression has been suggested as a management tool for mitigating detrimental effects of inbreeding depression, but the role of introgression in species conservation has been controversial, partly because population-level impacts of genetic introgressions are not well understood. Concerns about potential inbreeding depression in the endangered Florida panther (Puma concolor coryi) led to the release of eight female Texas pumas (P. c. stanleyana) into the Florida panther population in 1995. We used long-term reproductive data (1995–2008) collected from 61 female Florida panthers to estimate and model reproduction probability (probability of producing a litter) and litter size, and to investigate the influence of intentional genetic introgression on these parameters. Overall, 6-month probability of reproduction (±1SE) was 0.232 ± 0.021 and average litter size was 2.60 ± 0.09. Although F₁ admixed females had a lower reproduction probability than females with other ancestries, this was most likely because kittens born to F₁ females survive better; consequently, these females are unavailable for breeding until kittens are independent. There was no evidence for the effect of ancestry on litter size or of heterozygosity on probability of reproduction or litter size. In contrast, earlier studies have shown that genetic introgression positively affected Florida panther survival. Our results, along with those of earlier studies, clearly suggest that genetic introgression can have differential effects on components of fitness and highlight the importance of examining multiple demographic parameters when evaluating the effects of management actions.     

Does the Initial Floristic Composition model of succession really work?

Harvey & Holzman, in this issue of the Journal of Vegetation Science, describe divergent successional pathways after fire in Pinus muricata forest. Fourteen years after fire, the shrub Ceanothus thyrsiflorus had occupied flat parts of the area. They predicted it would continue to prevent succession to P. muricata forest, as in the initial floristic composition concepts of Clements and Egler.     

Sperm quality and fertility of boar seminal doses after 2 days of storage: Does the type of extender really matter?

The present approach was designed to evaluate the extender effects on sperm quality and fertility of short-term refrigerated seminal doses from Landrace boars lodged in husbandry-controlled conditions. For this purpose, we analyzed the sperm quality of seminal doses diluted in short-term (Beltsville Thawing Solution) and extra-long-term (Duragen) extenders from Days 0 to 2 of storage at 17 °C during an 8-month period. Pregnancy rates and litter size were evaluated from double inseminations within an interval of 12 hours (36 and 48 hours of refrigeration) of multiparous females using seminal doses diluted in each extender type. Sperm quality was assessed from the analyses of sperm motility and kinetics, sperm viability, expressed as plasma and acrosome membrane integrity, membrane lipid disorder, intracellular calcium levels, and acrosin activity. Results indicated significant differences between the extenders in the sperm quality of seminal doses. Therefore, the seminal doses diluted in Duragen had higher percentages of progressive motile spermatozoa and membrane-intact spermatozoa than those diluted in Beltsville Thawing Solution throughout all the experimental months. Nevertheless, despite these differences in preserving the sperm quality, pregnancy rates (>90%) and litter sizes (>10 piglets born per litter) were similar between the extenders. Our results had great relevance from a practical point of view because they reported lack of an extender effect on the reproductive performance of seminal doses during short-tem storage.     

Does the type of matrix matter? A quantitative review of the evidence

It has been increasingly recognized that the type of matrix surrounding habitat patches can affect biodiversity in landscapes, but there were only qualitative reviews of the subject focused on particular taxonomic groups. We present a quantitative review of studies from 1985 to 2008 that compared effects of different matrix types on individuals, populations and communities. We compiled 104 studies, most on animals, covering a broad range of landscape types and spatial scales. Most studies were empirical, focused on individuals and communities, and evaluated abundance/richness in the patch as the dependent variable. The type of matrix surrounding habitat patches influenced the studied parameters in 95% of the studies, but such effects were overall smaller compared to patch size or isolation effects. Matrix type effects were strongly species-specific, with different species responding differently to matrix type in 96% of studies comparing species or group of species. In 88% of studies, matrix types more similar in structure to the patch had higher quality for the studied organisms from the point of view of functional connectivity. Overall, the type of matrix is important, but patch size and isolation are the main determinants of ecological parameters in landscapes. Matrix quality generally increases with increasing structural similarity with habitat patches, a pattern that could be used as a general guideline for management of the matrix in fragmented landscapes.     

Can a thermally tolerant symbiont improve the future of Caribbean coral reefs?

The detrimental effect of climate change induced bleaching on Caribbean coral reefs has been widely documented in recent decades. Several studies have suggested that increases in the abundance of thermally tolerant endosymbionts may ameliorate the effect of climate change on reefs. Symbionts that confer tolerance to temperature also reduce the growth rate of their coral host. Here, we show, using a spatial ecosystem model, that an increment in the abundance of a thermally tolerant endosymbiont (D1a) is unlikely to ensure the persistence of Caribbean reefs, or to reduce their rate of decline, due to the concomitant reduction in growth rate under current thermal stress predictive scenarios. Furthermore, our results suggest that given the documented vital rates of D1a‐dominated corals, increasing dominance of D1a in coral hosts may have a detrimental effect by reducing the resilience of Caribbean reefs, and preventing their long‐term recovery. This is because Caribbean ecosystems appear to be highly sensitive to changes in the somatic growth rate of corals. Alternative outcomes might be expected in systems with different community‐level dynamics such as reefs in the Indo‐Pacific, where the ecological costs of reduced growth rate might be far smaller.     

Does point-of-sale nutrition information improve the nutritional quality of food choices?

Point-of-sale nutrition information has been adopted by numerous grocery stores to respond to the demand for easy-to-understand nutrition labeling by consumers. Although there is conflicting evidence regarding the effectiveness of providing nutrition information, previous research indicates simplified shelf nutrition labels may lead to healthier choices. However, these studies have not examined how different consumer segments respond to these labels, nor the differential impacts across foods. Using household purchase data from a store that voluntarily adopted the (now defunct) NuVal shelf nutrition labels (a 1-100 numeric score derived from a nutrition-profiling algorithm), we assess NuVal impacts across different consumers and foods. NuVal scores potentially influence not only purchase quantity but also likelihood of buying. Thus, the effect of NuVal was measured by estimating a two-part model and predicting consumers’ unconditional purchase responses. We found evidence of heterogeneous impacts of NuVal across consumers and foods. High-income households and households with children shifted their yogurt and frozen dinner purchases to more healthful items. In contrast, households with children and households headed by heads with college education slightly shifted their canned soup purchases to less healthful options. Our findings suggest that specific foods and consumer segments are influenced by simplified shelf nutrition information and further research is necessary to better understand its effect on consumer dietary quality.     

Hereditary hemochromatosis genetic testing of at-risk children: what is the appropriate age?

The objective of this study was to consider the objective evidence and ethical arguments for the appropriate age to test children at risk of developing hereditary hemochromatosis. A literature search for information on iron overload in children, onset of disease expression for hemochromatosis, and recommendations for age of cascade screening was undertaken. We examined the objective evidence and arguments for testing in early childhood and those for delaying testing until later teenage years. Cascade testing of offspring of people with hemochromatosis is widely advocated because it is an easily preventable disease. The ideal age to test those offspring is a matter of debate. Some authorities advocate testing at a very young age whereas others recommend delaying testing until late teenage years. To date there has been no published overview of the objective evidence and arguments central to this debate. In children who are C282Y homozygous, iron overload is rare in the first two decades of life and associated morbidity has only been documented in 1 patient. In the cascade setting, genetic testing for hemochromatosis need not be offered until late teenage years.     

Can dietary intake of phase 2 protein inducers affect the rising epidemic of diseases such as type 2 diabetes?

I propose that those populations with a long history of agriculture, particularly where survival was dependent upon relatively few food types, were selected for resistance to diseases such as type 2 diabetes. The basis for this resistance is hypothesized to be a higher basal level of ability to scavenge strong oxidants than found in populations whose recent ancestors depended to a great extent on gathering for their subsistence. Specifically, I hypothesize that selective pressures on populations whose ancestors ate a very restricted diet resulted in the development of populations with high basal levels of phase 2 protein gene expression; a consequence of which is that their tissues have a greater ability to cope with oxidative stress. In contrast, populations with a recent ancestry of hunting and gathering are more dependent upon the consumption of dietary phase 2 protein inducers for adequate phase 2 gene expression necessary for maintaining their tissues' abilities to cope with oxidative stress. This hypothesis can be readily tested by examining basal and induced phase 2 protein gene expression in umbilical cord fibroblasts, obtained from infants of different genetic backgrounds, grown in cell culture.     

Does the type of exercise affect tryptophan catabolism in horses?

Tryptophan (Trp) is an essential amino acid which metabolises via the kynurenine pathway to generate a number of bioactive substances referred to as kynurenines. Among those are 3-hydroxykynurenine (3-HKyn) and quinolinic acid, which are neurotoxic, as well as kynurenic acid (Kyna) and xanthurenic acid (XA), which, similarly to nicotinamide (NAm), show neuroprotective and anti-depressive effects. Routine exercise is known to modulate Trp metabolism in skeletal muscle and is thus believed to reduce the risk of depressive states in humans and laboratory animals. Analogously, it was hypothesised that exercise can influence Trp metabolism in horses as well. The aim of this study was to evaluate the influence of two different types of exercise on Trp metabolism in horses of the same breed. A total of 32 purebred Arabian horses were involved in the study. The 22 three-year-old racehorses were subjected to short-time intense exercise. Ten other horses were made to perform endurance competitions at a distance of 80 km. Blood samples were collected at rest and following the end of the exercise period. Plasma concentrations of Trp, kynurenine (Kyn), Kyna, 3-HKyn, XA and NAm were determined using Ultra-High Performance Liquid Chromatography-Electrospray Ionisation-Tandem Mass Spectrometry. Short-time intense exercise led to an increase in plasma concentrations of Kyn, Kyna and XA. The endurance effort induced an increase in Kyna and a decrease in Trp and NAm levels. Both types of exercise, short-time intensive exercise and endurance exercise induced an increase in Trp metabolites, especially Kyna, and did not induce an increase in Trp level. Thus, from a pathophysiological perspective of the kynurenine pathway’s influence on mental state, both types of exercise induced beneficial effects in horses.     

Metabolic syndrome in type 1 diabetes mellitus. Does it have any impact on the course of pregnancy?

To determine whether the symptoms of metabolic syndrome (MS), if accompanied by oxidative stress (OS), in type 1 diabetes mellitus (DM) patients could affect the course of pregnancy and the perinatal outcome. Oxidized low density lipoproteins (ox-LDL) and total lipid peroxides (TLP) were studied in 98 pregnant women with type 1 DM in the I(st) and III(rd) trimesters. 24% of the participants met the criteria of MS. Vascular complications were significantly more frequent in the MS-group (41.9% vs. 17.4% in the non-MS group, p<0.05). No differences in the markers of OS between the MS and the non-MS groups were noted in either the I(st) or the III(rd) trimester. A significant gestational rise in Per-Ox was found in both groups. Chronic hypertension was associated with significant differences in ox-LDL levels in both the I(st) and III(rd) trimester. No differences in perinatal outcome, as measured by abnormal birth weight or poor neonatal status (Apgar score<6, umbilical venous and/or arterial pH<7.20), were found. Conclusions: 1) MS in type 1 DM is associated with some changes in markers of oxidative stress, but it poses no additional risk to the course of pregnancy and perinatal outcome in properly controlled and treated pregnant women with type 1 DM. 2) Maternal hypertension is the only component of MS in diabetic pregnancy that is associated with significant changes in markers of oxidative stress. 3) MS is significantly more frequent in diabetic pregnant women with co-existing vascular complications and obesity.