Maternal weight gain induced by an obesogenic diet affects adipose accumulation, liver weight, and insulin homeostasis in the rat offspring depending on the sex

BACKGROUND

The aim of this research was to analyze the influence of the maternal dietary intake before pregnancy, as well as the parental impact on the response to a transgenerational high-fat-diet in rats.

METHODS

Ten female Wistar rats were fed a standard or a high-fat-sucrose (HFS) diet in the 8 weeks prior to pregnancy. Adult offsprings were assigned to a control or obesogenic diet for 8 weeks. Then, rat tissues and plasma samples were collected for analyzing tissue weight, liver triglycerides, and biochemical parameters such as triglycerides, HDL cholesterol, glucose, and insulin levels.

RESULTS

The offspring of rats fed a HFS diet gained less weight when they were fed the same diet than those fed a HFS diet combined with maternal control diet. Insulin levels were higher in rats fed a HFS diet (p<0.05) in both sexes; however, maternal HFS diet reversed, partially in males and total- ly in females, this hormonal imbalance. In male newborns, diet-induced maternal weight gain before pregnancy significantly influenced visceral (R 2 =0.373) and subcutaneous (R 2 =0.239) adipose deposition as well as liver weight (R 2 =0.130). Paternal genetic make-up was also a relevant factor affecting adiposity in both sexes (R 2 =0.333 in visceral fat; R 2 =0.183 in subcutaneous fat in males, and 0.292 and 0.282, respectively in females) as well as plasma triglycerides (R 2 =0.193 in males and R 2 =0.251 in females).

CONCLUSIONS

The genetic parental background and pre-natal maternal diet are important factors in the response to a hypercaloric diet and affect body composition and glucose homeostasis traits, including insulin secretion and homeostatic model assessment index.

Fatty acid composition of adipose tissue triglycerides after weight loss and weight maintenance: the DIOGENES study

Fatty acid composition of adipose tissue changes with weight loss. Palmitoleic acid as a possible marker of endogenous lipogenesis or its functions as a lipokine are under debate. Objective was to assess the predictive role of adipose triglycerides fatty acids in weight maintenance in participants of the DIOGENES dietary intervention study. After an 8-week low calorie diet (LCD) subjects with > 8 % weight loss were randomized to 5 ad libitum weight maintenance diets for 6 months: low protein (P)/low glycemic index (GI) (LP/LGI), low P/high GI (LP/HGI), high P/low GI (HP/LGI), high P/high GI (HP/HGI), and a control diet. Fatty acid composition in adipose tissue triglycerides was determined by gas chromatography in 195 subjects before the LCD (baseline), after LCD and weight maintenance. Weight change after the maintenance phase was positively correlated with baseline adipose palmitoleic (16:1n-7), myristoleic (14:1n-5) and trans-palmitoleic acid (16:1n-7t). Negative correlation was found with baseline oleic acid (18:1n-9). Lower baseline monounsaturated fatty acids (14:1n-5, 16:1n-7 and trans 16:1n-7) in adipose tissue triglycerides predict better weight maintenance. Lower oleic acid predicts lower weight decrease. These findings suggest a specific role of monounsaturated fatty acids in weight management and as weight change predictors.

Influence of different oxygen supply on metabolic markers and gene response in murine adipocytes

Obese subjects often present a low-grade chronic inflammation in the white adipose tissue, which seems to play an important role in the initiation and development of obesity-related diseases. It has been reported that this inflammatory process may be due to a hypoxic state occuring within this tissue. Oxygen is used in current medicine as a treatment for several conditions. The aim of this study is to analyze the effects of 95 percent O2 on specific metabolic variables and on the expression of some genes on murine adipocytes. 3T3-L1 adipocytes were exposed during 48 h to different treatments: 95 percent O2 hyperoxia (HPx group), CoCl2 (CoCl2 group), hyperoxia with CoCl2 (HPx+CoCl2 group) and 1 percent O2 hypoxia (Hx group). Cell viability, intracellular ROS content, glucose utilization, lactate and glycerol concentrations were measured. Also, mRNA expression of HIF-1alpha, GLUT-1, ANGPTL4, PPAR-gamma, adiponectin, IL-6 and MCP-1 genes was analyzed. Importantly, 95 percent O2 decreased cell viability and increased intracellular ROS production. Also, glycerol and lactate release were significantly increased and decreased, respectively, in HPx treated cells. This treatment also provoked a down-regulation of GLUT-1 and ANGPTL-4, while IL-6 and MCP-1 were up-regulated. Exposure to a hyperoxia of 95 percent O2 provoked an inflammatory response in adipocytes. The two hypoxia-inducing conditions (CoCl2 and 1 percent O2) produced different outcomes in metabolic measurements as well as in the expression of some genes (GLUT-1, ANPGTL4, PPAR-gamma and adiponectin), while it remained similar in others (HIF-1alpha, IL-6 and MCP-1). Indeed, hyperoxia increased significantly the ROS levels and the lipolytic activity, while it reduced lactate production. In addition to the effects on inflammation, the changes in GLUT-1, ANGPTL4 and PPAR-gamma genes lead to suppose that hyperoxia may be beneficial for the hypertrophied adipose tissues of obese subjects and for improving insulin sensitivity.

Fabrication of a nanostructure thermal property measurement platform

Measurements of the electrical and thermal transport properties of one-dimensional nanostructures (e.g. nanotubes and nanowires) are typically obtained without detailed knowledge of the specimen's atomic-scale structure or defects. To address this deficiency, we have developed a microfabricated, chip-based characterization platform that enables both transmission electron microscopy (TEM) of the atomic structure and defects as well as measurement of the thermal transport properties of individual nanostructures. The platform features a suspended heater line that physically contacts the center of a suspended nanostructure/nanowire that was placed using in situ scanning electron microscope nanomanipulators. Suspension of the nanostructure across a through-hole enables TEM characterization of the atomic and defect structure (dislocations, stacking faults, etc) of the test sample. This paper explains, in detail, the processing steps involved in creating this thermal property measurement platform. As a model study, we report the use of this platform to measure the thermal conductivity and defect structure of a GaN nanowire.

Predictors of weight loss maintenance and attrition during a 6-month dietary intervention period: results from the DiOGenes study

There is a need to develop tools to predict individual weight loss maintenance and attrition prognosis. We aimed to identify predictors of weight loss maintenance outcome and attrition in subjects from eight European countries in the DiOGenes project. A total of 932 overweight/obese subjects (body mass index: 27-42 kg m(-2) ) were enrolled in an 8-week low-calorie diet (LCD). The 776 subjects (83%) who achieved at least 8% reduction in their initial body weight were randomized into five dietary arms varying in protein content and glycemic index for a 6-month weight maintenance period. Baseline characteristics, weight loss at weeks 1, 3 and 8 of LCD were assessed as predictors of weight loss maintenance and attrition using multivariate regression and correlation models. The multivariate model showed that the 6-month weight loss maintenance was predicted by: 7.889 - 0.343 × weight loss at week 3 + 1.505 × weight loss at week 8 + 2.422 × gender (0 = male and 1 = female gender) (R(2)  = 51%, P = 0.0001). A greater weight loss at week 8 was associated with a lower attrition during the subsequent 6-month dietary intervention period (OR = 0.92, 95% CI: 0.88-0.97, P = 0.001). Furthermore, the men showed an increased likelihood for attrition during the dietary intervention period (OR = 1.54, 95% CI: 1.07-2.20, P = 0.02). A greater weight loss during 8 weeks of LCD and female gender predict better 6-month weight maintenance of weight loss, whereas the baseline characteristics did not predict outcome. Attrition could be strongly predicted by gender and weight loss during LCD.

Regulation by chronic-mild stress of glucocorticoids, monocyte chemoattractant protein-1 and adiposity in rats fed on a high-fat diet

Stress has been reported as a widespread problem and several studies have linked obesity and inflammation-related diseases. Moreover, the combination of suffering from chronic stress and high energy intake might be related to the onset of some metabolic diseases. To study the possible relationships between stress, inflammatory status and obesity, a chronic-mild stress (CMS) paradigm with a high-fat dietary intake model (Cafeteria diet) was implemented on male Wistar rats for 11 weeks. Stress and dietary intake effects on animal adiposity, serum biochemical as well as glucocorticoids and inflammation markers were all analyzed. As expected, consuming a high-fat diet increased body weight, adiposity and insulin resistance in non-stressed animals. A decrease of total white adipose tissue (WAT) and an increase of fecal glucocorticoids, as well as angiotensinogen, and monocyte chemoattractant protein-1 (MCP-1) expression level in retroperitoneal WAT were found only on control-stressed rats. Regarding the serum MCP-1, a decrease was observed on animals under CMS while being fed Cafeteria diet. Furthermore, 11β-hydroxysteroid dehydrogenase activity, a glucocorticoid and obesity biomarker in the liver, was influenced by high-fat diet intake but not by stress. Finally, statistical analysis showed a strong relation between MCP-1 expression levels in retroperitoneal WAT, fecal corticosterone and total WAT. This trial proved that CMS induced a glucocorticoid-mediated response, which was reduced by the intake of a Cafeteria diet. These findings suggest that a high-fat diet could protect against a stress condition and revealed a different behavior to a stressful environment depending on the nutritional status.

Vitamin C inhibits leptin secretion and some glucose/lipid metabolic pathways in primary rat adipocytes

Antioxidant-based treatments are emerging as an interesting approach to possibly counteract obesity fat accumulation complications, since this is accompanied by an increased systemic oxidative stress. The aim of this study was to analyze specific metabolic effects of vitamin C (VC) on epididymal primary rat adipocytes. Cells were isolated and incubated for 72 h in culture medium, in the absence or presence of 1.6 nM insulin, within a range of VC concentrations (5-1000 microM). Glucose- and lipid-related variables as well as the secretion/expression patterns of several obesity-related genes were assessed. It was observed that VC dose dependently inhibited glucose uptake and lactate production, and also reduced glycerol release in both control and insulin-treated cells. Also, VC caused a dramatic concentration-dependent fall in leptin secretion especially in insulin-stimulated cells. In addition, VC (200 microM) induced Cdkn1a and Casp8, partially inhibited Irs3, and together with insulin drastically reduced Gpdh (listed as Gpd1 in the MGI database) gene expressions. Finally, VC and insulin down-regulatory effects were observed on extracellular and intracellular reactive oxygen species production respectively. In summary, this experimental assay describes a specific effect of VC in isolated rat adipocytes on glucose and fat metabolism, and on the secretion/expression of important obesity-related proteins.

Dietary strategy to manipulate ad libitum macronutrient intake, and glycaemic index, across eight European countries in the Diogenes Study

The aim of this study was to describe the development and implementation of a multifaceted, low-fat, weight-loss strategy for a Pan-European randomized controlled dietary intervention study, Diogenes. There were 891 families with at least one overweight/obese parent who underwent screening. Eligible, overweight/obese adults followed an 8-week weight-loss phase with a fixed low-energy diet (800 kcal). On attaining weight loss of > or = 8%, families were randomized to a 6- or 12-month low-fat (25-30%E) diet either based on national dietary guidelines or one of four interventions: low protein (LP)/low glycaemic index (LGI), LP/high GI (HGI), high protein (HP)/LGI and HP/HGI. The impact of each diet in preventing weight (re)gain was tested. A points-based system was used to manipulate dietary protein and carbohydrate. Manipulating carbohydrate composition involved substituting foods with a relatively high or low GI. A questionnaire was designed and completed by study investigators, providing feedback on the dietary intervention methods used to inform future interventions. The points system allowed macronutrient manipulations without compromising dietary flexibility or enforcing energy restrictions. Reported centre/participant differences in the ease of implementing the intervention may reflect dietary diversity and personal preferences for specific weight-management strategies. The points system provides a useful starting point for designing improved experimental paradigms for the manipulation of dietary intake in future trials.

Developing a methodology for assigning glycaemic index values to foods consumed across Europe

There is growing evidence that the glycaemic index (GI) of the diet is important with respect to body weight and metabolic disease risk. However, research is limited by the paucity of GI values for commonly consumed carbohydrate-rich foods in European countries. A new methodology has been developed for consistent assignment of GI values to foods across five European databases used in the Diogenes intervention study. GI values were assigned according to five decreasing levels of confidence (1) Measured values for specific foods; (2) Published values from published sources; (3) Equivalent values where published values for similar foods existed; (4) Estimated values assigned as one of three values representing low/medium/high GI ranges and (5) Nominal values assigned as 70, where no other value could be assigned with sufficient confidence. GI values were assigned to 5105 foods. In food records collected at baseline, the contribution to carbohydrate intake of foods assigned levels 1-2 ranged from 16% to 43% depending on country, and this increased to 53-81% including level 3 foods. The degree of confidence to assigned GI values differed across Europe. This standardized approach of assigning GI values will be made available to other researchers to facilitate further investigation into the effects of dietary GI on health.

The Diet, Obesity and Genes (Diogenes) Dietary Study in eight European countries - a comprehensive design for long-term intervention

Diogenes is a Pan-European, randomized, controlled dietary intervention study investigating the effects of dietary protein and glycaemic index on weight (re)gain, metabolic and cardiovascular risk factors in obese and overweight families in eight European centres. The article is methodological in character, and the presentation of 'results' will be limited to baseline characteristics of the study populations included. A total of 891 families with at least one overweight/obese parent underwent screening. The parents started an initial 8-week low-calorie diet and families with minimum one parent attaining a weight loss of > or = 8%, were randomized to one of five energy ad libitum, low-fat (25-30 E%) diets for 6 or 12 months: low protein/low glycaemic index, low protein/high glycaemic index, high protein/low glycaemic index, high protein/high glycaemic index or control (national dietary guidelines). At two centres the families were provided dietary instruction plus free foods for 6 months followed by 6-month dietary instruction only. At the remaining six centres the families received dietary instruction only for 6 months. The median weight loss during the low-calorie diet was 10.3 kg (inter-quartile range: 8.7-12.8 kg, n = 775). A total of 773 adults and 784 children were randomized to the 6-month weight (re)gain prevention phase. Despite major cultural and dietary regional differences in Europe, interventions addressing effects of dietary factors are feasible with a reasonable attrition.

A 3-year intervention with a Mediterranean diet modified the association between the rs9939609 gene variant in FTO and body weight changes

INTRODUCTION

The aim of this study was to analyze the effects of the rs9939609 (T/A) gene variant in fat mass and obesity-associated gene (FTO) on body weight changes after 3 years and its modification by a randomized nutritional intervention with a Mediterranean-style diet in a population of subjects at high cardiovascular risk.

DESIGN

A substudy of PREDIMED, which is a randomized trial aimed at assessing the effect of the Mediterranean diet (MD) for primary cardiovascular disease prevention. There were three nutritional intervention groups: two of them with a Mediterranean-style diet and the third was a control group advised to follow a conventional low-fat diet.

SUBJECTS

A total of 776 high cardiovascular risk subjects aged 55-80 years.

MEASUREMENTS

Anthropometric measurements were recorded at baseline and at 3 years. The participants were genotyped by RT-PCR, followed by allelic discrimination.

RESULTS

Homozygous subjects had the highest baseline body weight. The dominant model showed that subjects carrying the A allele had the lowest body weight gain (B=-0.685; P=0.022) after 3 years of nutritional intervention compared with nonmutated subjects (TT genotype) regardless of the nutritional intervention. Moreover, this effect was statistically significant in carriers of the A allele only among those allocated to the MD groups (B=-0.830; P=0.018), but it was not significant among those allocated to the control group (P for interaction=0.649).

CONCLUSION

This study confirmed the association between body weight and the FTO rs9939609 polymorphism. Interestingly, our results showed that, although at baseline the A allele was associated with higher body weight, after 3 years of nutritional intervention with a Mediterranean-style-diet, A-allele carriers had lower body weight gain than wild type subjects. No interaction between nutritional intervention and the polymorphism was found.

Association between leptin receptor (LEPR) and brain-derived neurotrophic factor (BDNF) gene variants and obesity: a case-control study

INTRODUCTION

Human and animal studies provide evidence for a relevant role of the leptin receptor (LEPR) and the brain-derived neurotrophic factor (BDNF) genes in energy homeostasis.

AIM

To assess the association between human LEPR and BDNF genetic variants with adult obesity.

DESIGN AND METHODS

Case-control study in Pamplona (Navarra, Spain) with adult obese subjects (n = 159) and normal weight controls (n = 154). Four common polymorphisms of the LEPR gene (Lys109Arg, Gln223Arg, Ser343Ser, Lys656Asn) and 17 variants of the BDNF gene, including the Val66Met variant, were genotyped.

RESULTS

No significant case-control differences were found in allele/genotype frequencies after adjusting for relevant co-variates. Haplotype analysis did not detect any significant association between LEPR or BDNF variants and obesity. No associations were found between LEPR variants and serum leptin levels.

CONCLUSIONS

Our results do not support a major role of LEPR or BDNF common polymorphisms in multifactorial adult obesity.

Ascorbic acid oral treatment modifies lipolytic response and behavioural activity but not glucocorticoid metabolism in cafeteria diet-fed rats

AIM

To analyse the effects of vitamin C (VC), a potent dietary antioxidant, oral supplementation on body weight gain, behavioural activity, lipolytic response and glucocorticoid metabolism in the early stages of diet-induced overweight in rats.

METHODS

Food intake, locomotive activity and faecal corticosterone were assessed during the 14 day trial period. After 2 weeks, the animals were sacrificed and the body composition, biochemical markers and lipolytic response from isolated adipocytes from retroperitoneal white adipose tissue were examined.

RESULTS

The intake of a high-fat diet by rats induced a significant increase in body weight, adiposity and insulin resistance markers as well as a decrease in faecal corticosterone levels compared with standard diet-fed rats. Interestingly, the animals fed on the cafeteria diet showed a significant increase in the isoproterenol-induced lipolytic response in isolated adipocytes. Furthermore, this cafeteria-fed group showed a reduced locomotive behaviour than the control rats. On the other hand, oral VC supplementation in animals receiving the high-fat diet restored the cafeteria diet effect in some of the analysed variables such as final body weight and plasma insulin to control group levels. Remarkably, increases in locomotive behaviour and a significant decrease in the lipolytic response induced by isoproterenol on isolated adipocytes from animals treated with VC were observed.

CONCLUSION

This work demonstrates that an oral ascorbic acid supplementation has direct effects on behavioural activity and on adipocyte lipolysis in early obesity stages in rats, which could indicate a protective short-term role of this vitamin against adiposity induced by chronic high-fat diet consumption.

Fat-to-glucose interconversion by hydrodynamic transfer of two glyoxylate cycle enzyme genes

The glyoxylate cycle, which is well characterized in higher plants and some microorganisms but not in vertebrates, is able to bypass the citric acid cycle to achieve fat-to-carbohydrate interconversion. In this context, the hydrodynamic transfer of two glyoxylate cycle enzymes, such as isocytrate lyase (ICL) and malate synthase (MS), could accomplish the shift of using fat for the synthesis of glucose. Therefore, 20 mice weighing 23.37 +/- 0.96 g were hydrodinamically gene transferred by administering into the tail vein a bolus with ICL and MS. After 36 hours, body weight, plasma glucose, respiratory quotient and energy expenditure were measured. The respiratory quotient was increased by gene transfer, which suggests that a higher carbohydrate/lipid ratio is oxidized in such animals. This application could help, if adequate protocols are designed, to induce fat utilization for glucose synthesis, which might be eventually useful to reduce body fat depots in situations of obesity and diabetes.

Insulin effect on adipose tissue (AT) adiponectin expression is regulated by the insulin resistance status of the patients

OBJECTIVE

The objective of the present study was to determine a possible depot-specific effect of insulin-stimulation on adiponectin gene expression in adipose tissue (AT) explants from subcutaneous and visceral AT. A secondary aim was to analyse the associations of adiponectin plasma levels, as well as control and insulin-stimulated gene expression levels with different features of the metabolic syndrome.

DESIGN

Visceral and subcutaneous AT biopsies were obtained from 20 subjects (10 men and 10 women) with morbid obesity. Metabolic syndrome and other clinical features were studied. Adiponectin expression from isolated adipocytes was measured both in control and after insulin-stimulation conditions by quantitative PCR.

RESULTS

Subcutaneous adipocytes expressed significantly higher amounts of adiponectin mRNA than visceral tissue (P = 0.027). Insulin increased adiponectin expression specifically in the omental tissue (P = 0.011). In these patients, waist : hip ratio was directly correlated with adiponectin expression in the visceral depot (r = 0.660; P = 0.014), while fasting glucose levels were inversely associated with adiponectin mRNA in the subcutaneous tissue (r =-0.604; P = 0.022). Adiponectin expression after addition of insulin was positively correlated with some metabolic risk factors (cholesterol, LDL-cholesterol, insulin, C-peptide). Interestingly, local insulin induced an up-regulation of adiponectin expression in the AT of those patients with higher metabolic syndrome disturbances.

CONCLUSIONS

Our results clearly demonstrate that insulin exerts a stimulating effect on adiponectin gene expression in a depot-specific manner. The AT response to insulin stimulus depends on the physiopathological situation, being higher in those individuals with impaired insulin-sensitivity and lipid metabolism.

Activated RHOA and peripheral axon regeneration

The regeneration of adult peripheral neurons after transection is slow, incomplete and encumbered by severe barriers to proper regrowth. The role of RHOA GTPase has not been examined in this context. We examined the expression, activity and functional role of RHOA GTPase and its ROK effector, inhibitors of regeneration, during peripheral axon outgrowth. We used qRT-PCR, quantitative immunohistochemistry, and assays of RHOA activation to examine expression in sensory neurons of rats with sciatic transection injuries. In vitro, we exposed dissociated adult sensory neurons, not grown on inhibitory substrates, to a RHOA-ROK inhibitor HA-1077 and measured neurite initiation and outgrowth. In vivo, we exposed early regenerating axons and Schwann cells directly to HA-1077 in a conduit connecting the proximal and distal stumps of transected sciatic nerves. Intact adult dorsal root ganglia sensory neurons expressed RHOA and ROK 1 mRNAs and protein and there were rises in RHOA after injury. Activated GTP-bound RHOA, undetectable in intact ganglia, was dramatically upregulated in both neurons and axons after injury. Adult rat sensory neurons in vitro demonstrated a dose-related increase in the initiation of neurite outgrowth, and in the proportion with long neurites when they were exposed to a ROK antagonist. Regenerative bridges that were directly exposed to the ROK inhibitor had a dose-related rise in the extent and distance of in vivo axon and partnered Schwann cell regrowth within them. RHOA activation and signaling are features of adult peripheral axon regeneration within its own milieu, independent of myelin. Inhibition of its activation may benefit peripheral axon lesions.

Total adiponectin and adiponectin multimeric complexes in relation to weight loss-induced improvements in insulin sensitivity in obese women: the NUGENOB study

AIM

Adiponectin increases insulin sensitivity, protects arterial walls against atherosclerosis, and regulates glucose metabolism, and is decreased in obese, insulin resistant, and type 2 diabetic patients. Adiponectin circulates in plasma as high, medium, and low molecular weight forms (HMW, MMW, and LMW). The HMW form was suggested to be closely associated with insulin sensitivity. This study investigated whether diet-induced changes in insulin sensitivity were associated with changes in adiponectin multimeric complexes.

SUBJECTS

Twenty obese women with highest and twenty obese women with lowest diet induced changes in insulin sensitivity (responders and non-responders respectively), matched for weight loss (body mass index (BMI)=34.5 (s.d. 2.9) resp. 36.5 kg/m(2) (s.d. 4.0) for responders and non-responders), were selected from 292 women who underwent a 10-week low-caloric diet (LCD; 600 kcal/d less than energy requirements). Plasma HMW, MMW, and LMW forms of adiponectin were quantified using Western blot method.

RESULTS

LCD induced comparable weight reduction in responders and non-responders by 8.2 and 7.6 kg. Homeostasis model assessment insulin resistance index decreased by 48.1% in responders and remained unchanged in non-responders. Total plasma adiponectin and the quantity of HMW and MMW remained unchanged in both groups, while LMW increased by 16.3% in non-responders. No differences between both groups were observed at baseline and after the study. Total plasma adiponectin, MMW, and LMW were negatively associated with fasting insulin levels at baseline.

CONCLUSION

No differences in total plasma adiponectin, HMW, MMW, and LMW forms were observed between responders and non-responders following 10-week LCD, suggesting that adiponectin is not a major determinant of weight loss-induced improvements in insulin sensitivity.

Facilitated sprouting in a peripheral nerve injury

During regeneration of injured peripheral nerves, local conditions may influence how regenerative axon sprouts emerge from parent axons. More extensive lesions might be expected to disrupt such growth. In this work, we discovered instead that long segmental crush injuries facilitate the growth and maturation of substantially more axon sprouts than do classical short crush injuries (20 mm length vs. 2 mm). At identical distances from the proximal site of axon interruption there was a 45% rise in the numbers of neurofilament labeled axons extending through a long segmental crush zone by 1 week. By 2 weeks, there was a 35% greater density of regenerating myelinated axons in long compared with short crush injuries just beyond (5 mm) the proximal injury site. Moreover, despite the larger numbers of axons, their maturity was identical and they were regular, parallel, associated with Schwann cells (SCs) and essentially indistinguishable between the injuries. Backlabeling with Fluorogold indicated that despite these differences, the axons arose from similar numbers of parent motor and sensory neurons. Neither injury was associated with ischemia. Both injuries were associated with rises in GFAP (glial acidic fibrillary protein) and p75 mRNAs, markers of SC plasticity but p75, GFAP and brain-derived neurotrophic factor mRNAs did not differ between the injuries. There was a higher local mRNA level of GAP43/B50 at 7 days following injury and a higher sonic hedgehog protein (Shh) mRNA at 24 h in long crush zones. GAP43/B50 protein and SHH protein both had prominent localization within regenerating axons. Long segmental nerve trunk crush injuries do not impair regeneration but instead generate greater axon plasticity that results in larger numbers of mature myelinated axons. The changes occur without apparent change in SC activation, overall nerve architecture or nerve blood flow. While the mechanism is uncertain, the findings indicate that manipulation of the nerve microenvironment can induce substantial changes in regenerative sprouting.

Epidemiology and outcome of primary community-acquired bacteremia in adult patients

We conducted this study to determine the associated factors and outcomes of community-acquired primary bacteremia (PB), to describe the most frequently isolated microorganisms, the antibiotic resistance pattern, and to guide the most appropriate antibiotic treatment. A total of 1,640 community-acquired bacteremia cases in nonneutropenic adults were consecutively enrolled from January 2003 to May 2006 and prospectively followed up. Nonconditional logistic regression methods were used with PB and death as dependent variables. Secondary bacteremia (SB) was present in 1,440 patients, and 200 (12%) cases were PB. The independent factors associated with PB were male sex (OR 1.69, 95%CI 1.27-2.25, P = 0.001) and an ultimately or rapidly fatal prognosis for an underlying disease (OR 2.48, 95%CI 1.84-3.34, P = 0.001). The most frequently isolated microorganisms in PB were E. coli and other enterobacteria (26 and 22%, respectively) and S. aureus (15%). There were 28 and 37% ciprofloxacin-resistant E. coli strains in SB and PB, respectively (P = 0.2). Mortality was significantly higher in PB cases (13 vs 8%, P = 0.04). The independent factors associated with mortality in PB were ultimately or rapidly fatal prognosis of underlying disease (OR 2.1, 95%CI 1.41-3.13, P = 0.001), lack of fever at the moment of bacteremia (OR 2.38, 95%CI 1.18-4.76, P = 0.02) and incorrect empirical antibiotic therapy (OR 2.01, 95%CI 1.22-3.33, P = 0.006). The initial empiric antibiotic treatment was more frequently incorrect in PB than in SB, and this was a predictive factor for mortality in PB. The resistance pattern of E. coli, other enterobacteria and S. aureus in every setting should guide the most appropriate empirical treatment for PB.

Biofilm formation in uropathogenic Escherichia coli strains: relationship with prostatitis, urovirulence factors and antimicrobial resistance

PURPOSE

Escherichia coli strains are the most frequent cause of urinary tract infections. Biofilm formation allows the strains to persist a long time in the genitourinary tract and interfere with bacterial eradication. We determined the possible relationships between the different urinary tract infections, and in vitro biofilm formation, the presence of urovirulence factors and nalidixic acid resistance.

MATERIALS AND METHODS

A total of 151 E. coli strains collected from patients with cystitis (44 strains), pyelonephritis (75) and prostatitis (32) were analyzed for in vitro biofilm formation, the phylogenetic group, the presence of several urovirulence factors and resistance to nalidixic acid.

RESULTS

E. coli strains causing prostatitis produced biofilm in vitro more frequently than those causing other urinary tract infections and had a higher frequency of hemolysin (p = 0.03 and 0.0002, respectively). However, only hemolysin was independently associated with prostatitis. On the other hand, strains forming biofilm presented a significantly higher frequency of hemolysin and type 1 fimbriae expression.

CONCLUSIONS

Although hemolysin is the main virulence factor by which E. coli causes acute prostatitis, the association between hemolysin and biofilm formation may result in increased ability of E. coli strains to persist in the prostate.

Implication of biofilm formation in the persistence of urinary tract infection caused by uropathogenic Escherichia coli

Escherichia coli is the most frequent microorganism involved in urinary tract infection (UTI). Acute UTI caused by uropathogenic E. coli (UPEC) can lead to recurrent infection, which can be defined as either re-infection or relapse. E. coli strains causing relapse (n = 27) and re-infection (n = 53) were analysed. In-vitro production of biofilm, yersiniabactin and aerobactin was significantly more frequent among strains causing relapse. Biofilm assays may be helpful in selecting patients who require a therapeutic approach to eradicate persistent biofilm-forming E. coli strains and prevent subsequent relapses.

Genetics of Obesity: Gene × Nutrient Interactions

Obesity results from a long-term positive energy balance, in which gene-related differences may account for some of the disparities found in weight gain among populations. However, the rising prevalence of obesity in developed and developing societies must reflect lifestyle changes. Despite that the genetic background remains stable over many generations, obesity may be derived from a failure on the homeostasis systems, as a consequence of a dysfunction at the genetic level, which may be affected by changing environmental exposure (dietary habits, sedentarism, etc). In practice, obesity risk at least depends on two important factors, which mutually interact: 1) genetic variants and gene expression changes in candidate genes and 2) exposure to environmental risk factors. Disagreements among studies involving gene-nutrient interactions may reflect the difficulty of accurate measurement of specific types of dietary macro and micronutrients intake as well of phenotype assessment rather than a discrepancy in biological relevance. Identification of individuals who are genetically more likely to respond to particular dietary changes may be important for successful intervention in obesity treatment, since gene screening will allow health professionals to tailor-design weight management and dietary guidance in individuals with a genetic predisposition to become obese.

Rescue and regeneration of injured peripheral nerve axons by intrathecal insulin

Insulin peptide, acting through tyrosine kinase receptor pathways, contributes to nerve development or repair. In this work, we examined the direction, impact and repertoire of insulin signaling in vivo during peripheral nerve regeneration in rats. First, we demonstrated that insulin receptor is expressed on lumbar dorsal root ganglia neuronal perikarya using immunohistochemistry. Immunoblots and polymerase chain reactions confirmed the presence of both alpha and beta insulin receptor subunits in dorsal root ganglia. In vivo and in vitro assessment of dorsal root ganglion neurons showed preferential localization of insulin receptor to perikaryal sites. In vivo, intrathecal delivery of fluorescein isothiocyanate-labeled insulin identified localization around dorsal root ganglia neurons. The direction and impact of potential insulin signaling was evaluated by concurrently delivering insulin or carrier over a 2 week period using mini-osmotic pumps, either intrathecally, near nerve, or with both deliveries, following a selective sural nerve crush injury. Only intrathecal insulin increased the number and maturity of regenerating sensory sural nerve axons distal to the crush site. As well, only intrathecal insulin rescued retrograde loss of sural axons after crush. In a separate experiment, insulin also rescued retrograde loss and atrophy of deep peroneal, largely motor, axons post-injury. Intrathecal insulin increased the expression of calcitonin-gene-related peptide in regenerating sprouts, increased the number of visualized regenerating fiber clusters, and reduced downregulation of calcitonin-gene-related peptide in dorsal root ganglia neurons. Insulin delivered intrathecally does not appear to influence expression of insulin-like growth factor-1 at dorsal root ganglion neurons or near peripheral nerve injury, but was associated with upregulation of insulin receptor alpha subunit in dorsal root ganglia. Intrathecal insulin delivery was associated with greater recovery of thermal sensation and longer distances to stimulus response with the pinch test following sural nerve crush. Insulin signaling at neuron perikarya can drive distal sensory axon regrowth, rescue retrograde alterations of axons and alter axon peptide expression. Moreover, such actions are associated with upregulation of its own receptor.