Evaluation of suitable reference gene for real-time PCR in human umbilical cord mesenchymal stem cells with long-term in vitro expansion

In real-time quantitative PCR, the accuracy of normalized data is highly dependent on the stability of the reference genes. However, reference gene expression in a given cell type or experimental condition can vary considerably. The goal of this study was to establish a reliable set of reference genes for real-time PCR studies using human umbilical cord mesenchymal stem cells with long-term in vitro expansion. The stability of ten potential reference genes was examined in human umbilical cord mesenchymal stem cells. We found that Ywhaz and Rpl13a, not beta-actin or Gapdh, were the most stably expressed of the internal control genes in different passages of human umbilical cord mesenchymal stem cells. Ywhaz and Rpl13a could be used as reference genes for relative gene quantification and normalization purposes in real-time PCR studies of human umbilical cord mesenchymal stem cells.     

Interactions between the immune and nervous systems in pain

Immune cells and glia interact with neurons to alter pain sensitivity and to mediate the transition from acute to chronic pain. In response to injury, resident immune cells are activated and blood-borne immune cells are recruited to the site of injury. Immune cells not only contribute to immune protection but also initiate the sensitization of peripheral nociceptors. Through the synthesis and release of inflammatory mediators and interactions with neurotransmitters and their receptors, the immune cells, glia and neurons form an integrated network that coordinates immune responses and modulates the excitability of pain pathways. The immune system also reduces sensitization by producing immune-derived analgesic and anti-inflammatory or proresolution agents. A greater understanding of the role of the immune system in pain processing and modulation reveals potential targets for analgesic drug development and new therapeutic opportunities for managing chronic pain.     

Novel rhamnolipid biosurfactants produced by a polycyclic aromatic hydrocarbon-degrading bacterium Pseudomonas aeruginosa strain NY3

A novel rhamnolipid biosurfactant-producing and Polycyclic Aromatic Hydrocarbon (PAH)-degrading bacterium Pseudomonas aeruginosa strain NY3 was isolated from petroleum-contaminated soil samples. Strain NY3 was characterized by its extraordinary capacity to produce structurally diverse rhamnolipids. A total of 25 rhamnolipid components and 37 different parent molecular ions, representing various metal ion adducts (Na⁺, 2Na⁺ and K⁺), were detected by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Among these compounds are ten new rhamnolipids. In addition to its biosurfactant production, strain NY3 was shown to be capable of efficient degradation of PAHs as well as synergistic improvement in the degradation of high molecular weight PAHs by its biosurfactant. These findings have added novel members to the rhamnolipid group and expanded current knowledge regarding the diversity and productive capability of rhamnolipid biosurfactants from a single specific strain with variation of only one carbon source. Additionally, this paper lays the foundation for improvement in the yield of NY3BS and study of the degradation pathway(s) of PAHs in P. aeruginosa strain NY3.     

Urinary tract abnormalities in Chinese rural children who consumed melamine-contaminated dairy products: a population-based screening and follow-up study

Background

Kidney damage related to consumption of melamine-contaminated dairy products by young children in China has been described. However, no studies have reported on the population-based prevalence of kidney damage among exposed children or on the condition of affected children after follow-up.

Methods

We conducted an ultrasound-based screening in September 2008 of 7933 children younger than 36 months of age who lived in a rural area in China where the dairy products most highly contaminated with melamine were sold. We monitored children who had evidence of nephrolithiasis or hydronephrosis at screening using renal ultrasonography after one, three and six months. We also collected information from the mothers of affected children about consumption of melamine-contaminated products between June and August 2008.

Results

The overall prevalence of urinary tract abnormalities among screened children was 0.61% (95% confidence interval [CI] 0.45%–0.80%). The mean exposure dose of melamine was estimated to be 116 (range 36–220) mg per day. Of the 48 affected children, 43 (89.6%) were asymptomatic, 2 had symptoms and were hospitalized, and 3 had symptoms but treatment had been not sought for them. Of the 46 children for whom six-month follow-up information was available, renal abnormalities persisted in 5 children and resolved in the remaining 41.

Interpretation

Among children who underwent screening, 0.61% showed ultrasonographic evidence of nephrolithiasis or hydronephrosis. Most of the affected children were asymptomatic. The majority of the affected children recovered from the toxic effects of melamine over time without specific treatment. Renal abnormalities remained in 12% of the affected children.Contamination of dairy products with melamine in China has resulted in a widespread outbreak of serious kidney damage in children.^1–4 On Sept. 12, 2008, the Chinese government announced to the public that the outbreak had occurred and initiated various emergency responses, including the set-up of a high-level national coordinating group, free screening and treatment of affected children, thorough inspection of all dairy products and producers, timely release of information to the public, recalls of contaminated products, suspension of production of the contaminated milk and compensation to the families of affected children. More than 50 000 children have been hospitalized and six have died because of kidney damage.⁵Melamine is a nitrogen-containing compound commonly used in chemical industry. Because its addition to milk elevates apparent protein content, raw milk was intentionally adulterated with melamine in the production-chain, leading to contamination of dairy products and high-level exposure of thousands of children.⁶Melamine is known to cause formation of calculi in weanling rats and has led to acute renal failure in cats and dogs consuming melamine-contaminated pet foods.^7,8 In humans, melamine-related disease has been recognized only recently, and the full adverse effects of exposure remain unknown.^4,9 A clinicopathologic study suggests that the size of urinary stones is related to melamine concentration.⁹ A recent hospital-based study in Beijing reported the prevalence of nephrolithiasis was 8.5% among children who were exposed and referred by other hospitals.¹⁰However, no studies have reported on the population-based prevalence of kidney disease among exposed children, nor have follow-up reports been released about affected children. We performed a population-based screening and follow-up study involving residents of a rural area situated close to the manufacturer of Sanlu dairy products, which was the source of the most severely melamine-contaminated products in the mainland of China.¹¹ The study was approved by the Institutional Review Board of Peking University.     

An h-type thioredoxin functions in tobacco defense responses to two species of viruses and an abiotic oxidative stress

Various thioredoxin (Trx) proteins have been identified in plants. However, many of the physiological roles played by these proteins remain to be elucidated. We cloned a TRXh-like gene predicted to encode an h-type Trx in tobacco (Nicotiana tabacum) and designated it NtTRXh3, based on the biochemical activity of the NtTRXh3 protein. Overexpression of NtTRXh3 conferred resistance to Tobacco mosaic virus and Cucumber mosaic virus, both of which showed reduced multiplication and pathogenicity in NtTRXh3-overexpressing plants compared with controls. NtTRXh3 overexpression also enhanced tobacco resistance to oxidative stress induced by paraquat, an herbicide that inhibits the production of reducing equivalents by chloroplasts. The NtTRXh3 protein localized exclusively to chloroplasts in coordination with the maintenance of cellular reducing conditions, which accompanied an elevation in the glutathione/glutathione disulfide couple ratio. NtTRXh3 gene expression and NtTRXh3 protein production were necessary for these defensive responses, because they were all arrested when NtTRXh3 was silenced and the production of NtTRXh3 protein was abrogated. These results suggest that NtTRXh3 is involved in the resistance of tobacco to virus infection and abiotic oxidative stress.     

Inter- and intra-genomic transfer of small chromosomal segments in wheat-rye allopolyploids

Newly synthesized wheat-rye allopolyploids, derived from Triticum aestivum Mianyang11 × S. cereale Kustro, were investigated by sequential fluorescent in situ hybridization (FISH) and genomic in situ hybridization (GISH) using rye tandem repeat pSc200 and rye genomic DNA as probes, respectively, over the first, second and third allopolyploid generations. FISH signals of pSc200 could be observed at both telomeres/subtelomeres of all 14 chromosomes of the parental rye. In the first allopolyploid generation, there were ten rye chromosomes bearing FISH signals at both telomeres/subtelomeres and four rye chromosomes bearing FISH signals at only one telomere/subtelomere. However, in the second and the third allopolyploid generations, there were 12 rye chromosomes bearing FISH signals at both telomeres/subtelomeres and 2 rye chromosomes bearing FISH signals at only one telomere/subtelomere. Rye telomeric segments were transferred to the centromeric region of wheat chromosomes in some cells and small segments derived from non-telomeric regions of rye chromosome were transferred to the telomeric region of wheat chromosomes in some other cells. These observations indicated that the rye telomeric/subtelomeric region was unstable in newly synthesized wheat-rye allopolyploids and allopolyploidization was accompanied by rapid inter/intra-genomic exchange. The inter-genomic exchange may have occurred in somatic cells.     

Expression and purification of moricin CM4 and human β-defensins 4 in Escherichia coli using a new technology

Different strategies have been developed to produce small antimicrobial peptides using recombinant techniques. Here we report a new technology of biosynthesis of moricin CM4 and human β-defensins 4 (HβD4) in the Escherichia coli. The CM4 and HβD4 gene were cloned into a vector containing the tags elastin-like peptide (ELP) and intein to construct the expression vector pET-EI-CM4 and pET-EI-HβD4. All the peptides, expressed as soluble fusions, were isolated from the protein debris by the method called inverse transition cycling (ITC) rather than traditional immobilized metal affinity chromatography (IMAC) and separated from the fusion leader by self-cleavage. Fully reduced peptides that were purified exhibited expected antimicrobial activity. The approach described here is a low-cost, convenient and potential way for generating small antimicrobial peptide.     

Synthesis of novel ligustrazine derivatives as NA+/H+ exchange inhibitors

A novel series of 3,5,6‐trimethylpyrazine‐2‐methoxy (or methylamino) substituted benzoyl‐guanidine derivatives were designed and synthesized as Na⁺/H⁺ exchange (NHE) inhibitors. In this study, compounds with electron‐withdrawing substituents on the benzene ring seemed to improve NHE‐1 inhibitory activities. Compounds 6d, 6k , and 6l were found to be potent inhibitors of NHE‐1 (IC₅₀=3.0±1.6, 3.0±1.4, and 1.6±0.4 nmol/l, resp.). Furthermore, they showed a remarkable reduction of infarct size in the rat myocardial infarction model in vivo.