Malic enzyme 1 genotype is associated with backfat thickness and meat quality traits in pigs

Malic enzyme 1 (ME1) is a part of the tricarboxylate shuttle that provides NADPH and acetyl-CoA required in fatty acid biosynthesis. The pig ME1 locus maps on the proximal end of chromosome 1, where a quantitative trait loci (QTL) affecting fat deposition has been previously described. We amplified fragments of 1457 and 1459 bp that corresponded to the complete coding region and the 3'-untranslated region (UTR), respectively, of the pig ME1 gene. The sequences of these two fragments in pigs from three breeds (Landrace, Large White and Piétrain) contained five single nucleotide polymorphisms (SNP) in the 3'-UTR: C1706T, G1762T, A1807C, C1857A and T1880A. Three haplotypes were found in two generations of a selected Landrace population: H1 (C1706 G1762 A1807 C1857 A1880), H2 (C1706 G1762 A1807 C1857 T1880) and H3 (T1706 T1762 C1807 A1857 T1880). Using Bayesian association analyses, significant associations (highest posterior density at 95%) between ME1 genotype and backfat (BF) thickness at 171 days and muscular pH were found in a Landrace population.

Tumor VEGF expression and serum VEGF levels are independent prognostic factors in curatively resected gastric cancer patients

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Background: Increased serum and/or tumor vascular endothelial growth factor (VEGF) and urokinase-type plasminogen activator (uPA) have been shown to predict poor survival in several neoplasms, but their prognostic value in gastric cancer (GC) remains unknown. Methods: Serum VEGF (S-VEGF) and uPA concentrations were measured by commercially available ELISA in 20 healthy controls and 97 GC patients (70% I-II stages) before an R0 gastric resection. Tumor expression of VEGF and uPA were assessed by immunohistochemistry. Additional variables, including demographic, histological and therapeutic data were also evaluated. Univariate (Kaplan-Meier, log-rank test) and multivariate (Cox regression) analyses were performed to select prognostic factors regarding survival and tumor recurrence. Results: S-VEGF, but not uPA levels were significantly higher in GC patients than in controls. After a mean follow-up of 47 ± 3 months, the probability of cancer-related survival at 2, 5, and 10 years was 86%, 69% and 59%, respectively. Univariate analysis identified tumor VEGF expression (p=0.001) and high (> 289 pg/ml) S-VEGF levels (p=0.045), along with pTMN stage, grade of curability, perineural invasion, lymph node ratio, and extent of lymphadenectomy as variables associated with cancer-related survival. The mean disease-free survival was 20 ± 3 months, the probability of tumor recurrence being 78%, 62% and 62% at 2, 5 and 10 years, respectively. Prognostic variables for recurrence were the same as those identified for survival. Multivariate analysis identified tumor VEGF expression and high S-VEGF levels as independent prognostic survival factors. Conclusions: After a long follow-up, tumor VEGF expression and S-VEGF levels are independent prognostic factors for recurrence and survival in curatively resected gastric cancer patients. Such markers for increased angiogenic activity might help to identify patients at high risk of recurrence that could mostly benefit from adjuvant therapies. It is tempting to speculate that trials assessing the potential benefit of a.ntiangiogenic agents might be particularly warranted in patients with resected GC and a highly angiogenic phenotype.

No significant financial relationships to disclose.

Metabolic syndrome, insulin resistance and the inflammation markers C-reactive protein and ferritin

BACKGROUND

Patients with metabolic syndrome (MS) have above-average risk of developing atherosclerosis and cardiovascular disease. Inflammation plays a key role in the development of atherosclerosis. High levels of the acute phase reactants C-reactive protein (CRP) and ferritin have been reported to correlate with various components of MS.

PATIENTS AND METHODS

The serum CRP, ferritin, glucose, insulin, triglycerides, HDL-cholesterol and total cholesterol concentrations of 598 obese or overweight patients were determined, together with relevant anthropometric parameters. Insulin resistance was evaluated by the HOMA method. MS was diagnosed using the ATP III criteria.

RESULTS

CRP levels were higher among patients with central obesity than in those without (5.8 vs 3.9 mg/l; P=0.003), and higher among those with fasting plasma glucose concentrations >or=110 mg/dl than in those with lower concentrations (7.4 vs 4.1 mg/l; P=0.01). Serum ferritin levels were higher among patients with triglyceride concentrations >or=150 mg/dl than in those with lower levels (76.8 vs 40.1 ng/ml; P<0.001), and higher among those with fasting plasma glucose concentrations >or=110 mg/dl than in those with lower concentrations (75.7 vs 41.7 ng/ml; P=0.005). The number of MS criteria that were satisfied increased with CRP and ferritin levels. Patients with insulin resistance also had higher CRP and ferritin levels than those without, 7.3 vs 4.3 mg/l for CRP (P=0.032) and 124.5 vs 80.1 ng/ml for ferritin (P<0.001).

CONCLUSIONS

MS and insulin resistance are associated with elevated serum CRP and ferritin. Evaluation of subclinical chronic inflammation in patients with MS and/or insulin resistance by determination of these markers might aid in their evaluation as candidates for aggressive intervention against cardiovascular risk factors.

Incomplete esophageal myotomy and early recurrence of an epiphrenic diverticulum

The established management of epiphrenic diverticula combines diverticulectomy with myotomy of the distal esophagus including the lower esophageal sphincter. We report a patient with prompt recurrence of an epiphrenic diverticulum after laparoscopic transhiatal diverticulectomy associated with esophagomyotomy and partial posterior fundoplication due to an incomplete myotomy.

Bifidobacterium longum requires a fructokinase (Frk; ATP:D-fructose 6-phosphotransferase, EC 2.7.1.4) for fructose catabolism

Although the ability of Bifidobacterium spp. to grow on fructose as a unique carbon source has been demonstrated, the enzyme(s) needed to incorporate fructose into a catabolic pathway has hitherto not been defined. This work demonstrates that intracellular fructose is metabolized via the fructose-6-P phosphoketolase pathway and suggests that a fructokinase (Frk; EC 2.7.1.4) is the enzyme that is necessary and sufficient for the assimilation of fructose into this catabolic route in Bifidobacterium longum. The B. longum A10C fructokinase-encoding gene (frk) was expressed in Escherichia coli from a pET28 vector with an attached N-terminal histidine tag. The expressed enzyme was purified by affinity chromatography on a Co(2+)-based column, and the pH and temperature optima were determined. A biochemical analysis revealed that Frk displays the same affinity for fructose and ATP (Km(fructose) = 0.739 +/- 0.18 mM and Km(ATP) = 0.756 +/- 0.08 mM), is highly specific for D-fructose, and is inhibited by an excess of ATP (>12 mM). It was also found that frk is inducible by fructose and is subject to glucose-mediated repression. Consequently, this work presents the first characterization at the molecular and biochemical level of a fructokinase from a gram-positive bacterium that is highly specific for D-fructose.

Identification of quantitative trait loci for production traits in commercial pig populations

The aim of this study was to investigate methods for detecting QTL in outbred commercial pig populations. Several QTL for back fat and growth rate, previously detected in experimental resource populations, were examined for segregation in 10 different populations. Two hundred trait-by-population-by-chromosome tests were performed, resulting in 20 tests being significant at the 5% level. In addition, 53 QTL tests for 11 meat quality traits were declared significant, using a subset of the populations. These results show that a considerable amount of phenotypic variance observed in these populations can be explained by major alleles segregating at several of the loci described. Thus, despite a relatively strong selection pressure for growth and back fat traits in these populations, these alleles have not yet reached fixation. The approaches used here demonstrate that it is possible to verify segregation of QTL in commercial populations by limited genotyping of a selection of informative animals. Such verified QTL may be directly exploited in marker-assisted selection (MAS) programs in commercial populations and their molecular basis may be revealed by positional candidate cloning.

Selective growth of mucolytic bacteria including Clostridium perfringens in a neonatal piglet model of total parenteral nutrition

BACKGROUND

Compromised barrier function and intestinal inflammation are common complications of total parenteral nutrition (TPN).

OBJECTIVE

We tested the hypothesis that the lack of enteral nutrients in TPN might select commensal or pathogenic bacteria that use mucus as a substrate, thereby weakening the protection provided by the intestinal mucus layer.

DESIGN

Ileal microbiota profiles of piglets fed by total enteral nutrition (TEN; n = 6) or TPN (n = 5) were compared with the use of 16S ribosomal DNA polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis and with a PCR-based method developed to specifically measure Clostridium perfringens concentrations. Ileal bacteria from TEN and TPN piglets were also examined for their ability to grow on mucin or sulfated monosaccharides.

RESULTS

Bacterial community structure was equally complex in the ileum of TEN and TPN piglets, but profiles clustered according to mode of nutrition. Sixty-two percent of total mucus-associated bacteria (100 colonies tested) in TPN compared with 33% of mucus-associated bacteria (100 colonies tested) in TEN ileal samples grew on mucin. Bacteria capable of using sulfated monosaccharides were also enriched in TPN samples. C. perfringens, an opportunistic pathogen, was specifically enriched in the TPN ileum (P < 0.05). These results were corroborated by cultivation-based studies that showed rapid growth of C. perfringens on mucin-based substrates.

CONCLUSIONS

Mucolytic potential is widespread among intestinal bacteria. Mucolytic bacteria in general and C. perfringens in particular were selected when enteral nutrients were withheld in this TPN piglet model. Similar enrichment processes may occur in humans nourished by TPN and may thereby contribute to intestinal dysfunction.

Primary systemic amyloidosis presenting as a colonic stricture: successful treatment with left hemicolectomy followed by autologous hematopoietic stem-cell transplantation: report of a case

Intestinal tract involvement by primary systemic amyloidosis is frequent but usually asymptomatic. Ischemic colitis caused by amyloid infiltration of wall blood vessels can occasionally be observed. We report a 62-year-old female with primary systemic amyloidosis who presented with intestinal obstruction caused by ischemic stricture of the sigmoid colon, secondary to submucosal amyloid deposition. The patient was successfully treated with surgical resection followed by high-dose chemotherapy and hematopoietic stem-cell transplantation. The clinical manifestations and differential diagnosis of gastrointestinal involvement of primary systemic amyloidosis, as well as its current treatment, are discussed.

Estrogen receptor specificity for the effects of estrogen in ovariectomized mice

Estrogen exerts a variety of important physiological effects, which have been suggested to be mediated via the two known estrogen receptors (ERs), alpha and beta. Three-month-old ovariectomized mice, lacking one or both of the two estrogen receptors, were given estrogen subcutaneously (2.3 micro g/mouse per day) and the effects on different estrogen-responsive parameters, including skeletal effects, were studied. We found that estrogen increased the cortical bone dimensions in both wild-type (WT) and double ER knockout (DERKO) mice. DNA microarray analysis was performed to characterize this effect on cortical bone and it identified four genes that were regulated by estrogen in both WT and DERKO mice. The effect of estrogen on cortical bone in DERKO mice might either be due to remaining ERalpha activity or represent an ERalpha/ERbeta-independent effect. Other effects of estrogen, such as increased trabecular bone mineral density, thymic atrophy, fat reduction and increased uterine weight, were mainly ERalpha mediated.

Complex regulatory network controls initial adhesion and biofilm formation in Escherichia coli via regulation of the csgD gene

The Escherichia coli OmpR/EnvZ two-component regulatory system, which senses environmental osmolarity, also regulates biofilm formation. Up mutations in the ompR gene, such as the ompR234 mutation, stimulate laboratory strains of E. coli to grow as a biofilm community rather than in a planktonic state. In this report, we show that the OmpR234 protein promotes biofilm formation by binding the csgD promoter region and stimulating its transcription. The csgD gene encodes the transcription regulator CsgD, which in turn activates transcription of the csgBA operon encoding curli, extracellular structures involved in bacterial adhesion. Consistent with the role of the ompR gene as part of an osmolarity-sensing regulatory system, we also show that the formation of biofilm by E. coli is inhibited by increasing osmolarity in the growth medium. The ompR234 mutation counteracts adhesion inhibition by high medium osmolarity; we provide evidence that the ompR234 mutation promotes biofilm formation by strongly increasing the initial adhesion of bacteria to an abiotic surface. This increase in initial adhesion is stationary phase dependent, but it is negatively regulated by the stationary-phase-specific sigma factor RpoS. We propose that this negative regulation takes place via rpoS-dependent transcription of the transcription regulator cpxR; cpxR-mediated repression of csgB and csgD promoters is also triggered by osmolarity and by curli overproduction, in a feedback regulation loop.

Structure of tetragonal hen egg-white lysozyme at 0.94 A from crystals grown by the counter-diffusion method

Very high quality crystals of tetragonal hen egg-white lysozyme were grown in the Advanced Protein Crystallization Facility (APCF) on board the Space Shuttle using a modified free-interface diffusion (FID) reactor designed ad hoc to have a longer diffusion path. This design allows the performance of true counter-diffusion experiments. Crystals were obtained under the classical chemical conditions defined 50 y ago with NaCl as a crystallizing agent and acetate pH 4.5 as a buffer. Counter-diffusion crystallization allows a "physical" instead of chemical optimization of growth conditions: indeed, this method screens for the best supersaturation conditions in a single trial and yields crystals of very high quality. A complete diffraction data set was collected at atomic resolution from one of these crystals using synchrotron radiation at the DESY-EMBL beamlines. The overall R(merge) on intensities in the resolution range 31-0.94 A was 5.2% and the data were 98.9% complete. Refinement was carried out with the programs CNS and SHELX97 to a final crystallographic R factor of 12.26% for 72 390 reflections. A mean standard uncertainty in the atomic positions of 0.024 A was estimated from inversion of blocked least-squares matrices. 22 side chains show alternate conformations and the loop 59-75 adopts in the same crystal packing two conformations that were observed for either triclinic or tetragonal lysozyme in previous high-resolution studies. In addition to 255 water molecules, the crystallizing agent (one hexacoordinated sodium ion and five chloride anions) participates in the ordered lysozyme hydration shell.

Female estrogen receptor beta-/- mice are partially protected against age-related trabecular bone loss

Recently, it has been shown that inactivation of estrogen receptor beta (ER-beta) by gene targeting results in increased cortical bone formation in adolescent female mice. To study the possible involvement of ER-beta in the regulation of the mature skeleton, we have extended the analyses to include 1-year-old ER-beta knockout mice (ER-beta-/-). Male ER-beta-/- mice did not express any significant bone phenotypic alterations at this developmental stage. However, the increase in cortical bone parameters seen already in the adolescent female ER-beta-/- mice was maintained in the older females. The aged female ER-beta-/- mice further exhibited a significantly higher trabecular bone mineral density (BMD) as well as increased bone volume/total volume (BV/TV) compared with wild-type (wt) mice. This was caused by a less pronounced loss of trabecular bone during adulthood in female ER-beta-/- mice. The growth plate width was unaltered in the female ER-beta-/- mice. Judged by the expression of the osteoclast marker tartrate-resistant acid phosphatase (TRAP) and cathepsin K (cat K; reverse-transcription-polymerase chain reaction [RT-PCR]) as well as the serum levels of C-terminal type I collagen cross-linked peptide, bone resorption appeared unaffected. However, an increase in the messenger RNA (mRNA) expression levels of the osteoblast marker core-binding factor alpha1 (Cbfa1) suggested an anabolic effect in bones of old female ER-beta-/- mice. In addition, the mRNA expression of ER-alpha was augmented, indicating a role for ER-alpha in the development of this phenotype. Taken together, the results show that ER-beta is involved in the regulation of trabecular bone during adulthood in female mice and suggest that ER-beta acts in a repressive manner, possibly by counteracting the stimulatory action of ER-alpha on bone formation.