Role of postreplicative DNA mismatch repair in the cytotoxic action of thioguanine

It is proposed here that the delayed cytotoxicity of thioguanine involves the postreplicative DNA mismatch repair system. After incorporation into DNA, the thioguanine is chemically methylated by S-adenosylmethionine to form S6-methylthioguanine. During DNA replication, the S6-methylthioguanine directs incorporation of either thymine or cytosine into the growing DNA strand, and the resultant S6-methylthioguanine-thymine pairs are recognized by the postreplicative mismatch repair system. Azathioprine, an immunosuppressant used in organ transplantation, is partly converted to thioguanine. Because the carcinogenicity of N-nitrosamines depends on formation of O6-alkylguanine in DNA, the formation of the analog S6-methylthioguanine during azathioprine treatment may partly explain the high incidence of cancer after transplantation.

A major gene affecting age-related hearing loss in C57BL/6J mice

A major gene responsible for age-related hearing loss (AHL) in C57BL/6J mice was mapped by analyses of a (C57BL/6J x CAST/Ei) x C57BL/6J backcross. AHL, as measured by elevated auditory-evoked brainstem response (ABR) thresholds, segregated among backcross mice as expected for a recessive, primarily single-gene trait. Both qualitative and quantitative linkage analyses gave the same genetic map position for the AHL gene (Ahl on chromosome 10, near D10Mit5. Marker assisted selection was then used to produce congenic lines of C57BL/6J that contain different CAST-derived segments of chromosome 10. ABR test results and cochlear histopathology of aged progenitors of these congenic lines are presented. Ahl is the first gene causing late-onset, non-syndromic hearing loss that has been reported in the mouse.

Altered patterns of gene expression in response to myocardial infarction

The use of cDNA microarrays has made it possible to simultaneously analyze gene expression for thousands of genes. Microarray technology was used to evaluate the expression of >4000 genes in a rat model of myocardial infarction. More than 200 genes were identified that showed differential expression in response to myocardial infarction. Gene expression changes were monitored from 2 to 16 weeks after infarction in 2 regions of the heart, the left ventricle free wall and interventricular septum. A novel clustering program was used to identify patterns of expression within this large set of data. Unique patterns were revealed within the transcriptional responses that illuminate changes in biological processes associated with myocardial infarction.

Randomised clinical trial: the effects of perioperative probiotic treatment on barrier function and post-operative infectious complications in colorectal cancer surgery - a double-blind study

BACKGROUND

Infection following abdominal operation remains a major factor affecting the morbidity of patients after surgery.

AIM

To determine the effects of perioperative administration of probiotics on the gut barrier function and the surgical outcome in patients undergoing elective colorectal surgery.

METHODS

One hundred patients with colorectal carcinoma were randomly divided into the control group (n = 50) and the probiotics group (n = 50). The probiotics were given orally for 6 days preoperatively and 10 days post-operatively. Outcomes were measured by bacterial translocation, gut permeability, the effect on the faecal microbiota, and the clinical outcomes such as infectious-related complications and gut defecation function.

RESULTS

Compared with the control group, probiotics group had increased transepithelial resistance (P < 0.05), reduced transmucosal permeation of horseradish peroxidase and lactulose/mannitol ratio, reduced bacterial translocation (P < 0.05), decreased ileal-bile acid binding protein (P < 0.05) and positive rate of blood bacterial DNA (P < 0.05) and an enhanced mucosal tight junction protein expression. They had decreased blood enteropathogenic bacteria and increased faecal bacterial variety. The post-operative recovery of peristalsis, incidence of diarrhoea, and infectious-related complications were also improved.

CONCLUSION

Probiotics can improve the integrity of gut mucosal barrier by benefiting the faecal microbiota, and decreasing infectious complications in patients with colorectal cancer undergoing colorectomy.

A novel assay for extracellular matrix remodeling associated with liver fibrosis: An enzyme-linked immunosorbent assay (ELISA) for a MMP-9 proteolytically revealed neo-epitope of type III collagen

OBJECTIVES

Accumulation of extracellular matrix (ECM) components and increased matrix-metalloprotease (MMPs) activity are hallmarks of fibrosis. We developed an ELISA for quantification of MMP-9 derived collagen type III (CO3) degradation.

DESIGN AND METHODS

A monoclonal antibody targeting a specific MMP-9 cleaved fragment of CO3 was used for development of a competitive ELISA. The assay was investigated in serum and tissues from bile duct ligated rats (BDL).

RESULTS

The ELISA showed no cross-reaction with either intact CO3, or other collagens. The intra- and inter-assay CV were below 10%. Liver fibrosis was demonstrated in BDL animals by semi quantitative scoring (P<0.0001). Serum levels of CO3-610 increased 2.5 fold in BDL animals (P<0.001). The CO3-610 levels were 5 fold higher in ex vivo cultures of fibrotic livers compared to controls (P<0.001).

CONCLUSION

We have developed a novel ELISA for measuring a specific fragment CO3 generated by MMP-9 important in pathogenesis of liver fibrosis.

The growing applications of SuFEx click chemistry

SuFEx (Sulfur Fluoride Exchange) is a modular, next generation family of click reactions, geared towards the rapid and reliable assembly of functional molecules.

A major gene affecting age-related hearing loss is common to at least ten inbred strains of mice

Inbred strains of mice offer promising models for understanding the genetic basis of human presbycusis or age-related hearing loss (AHL). We previously mapped a major gene affecting AHL in C57BL/6J mice. Here, we show that the same Chromosome 10 gene (Ahl) is a major contributor to AHL in nine other inbred mouse strains-129P1/ReJ, A/J, BALB/cByJ, BUB/BnJ, C57BR/cdJ, DBA/2J, NOD/LtJ, SKH2/J, and STOCK760. F1 hybrids between each of these inbred strains and the normal-hearing inbred strain CAST/Ei retain good hearing, indicating that inheritance of AHL is recessive. To follow segregation of hearing loss, F1 hybrids were backcrossed to the parental strains with AHL. Auditory-evoked brain-stem response thresholds were used to assess hearing in more than 1500 N2 mice and analyzed as quantitative traits for linkage associations with Chromosome 10 markers. Highly significant linkage was found in all nine strain backcrosses, with the highest probability (LOD > 70) near the marker D10Mit112. This map position for Ahl is near the waltzer mutation (v) and the modifier of deaf waddler locus (mdfw), suggesting the possibility of allelism. Results from an intercross of C57BL/6J and NOD/LtJ mice indicate that the 6- to 10-month difference in AHL onset between these two strains is not due to allelic heterogeneity of the Ahl gene.

Liquids at large negative pressures: water at the homogeneous nucleation limit

An isochoric cooling method for obtaining unprecedented tensions on liquids was used to determine the homogeneous nucleation limit for stretching of water at a variety of water densities. At densities in the range 0.55 to 0.68 gram per milliliter (g/ml), the data agree with the homogeneous nucleation temperatures measured by Skripov for superheated water at positive pressures. At densities between 0.68 and 0.93 g/ml, cavitation occurred only at negative pressures (that is, under tension). The cavitation tensions measured were in excellent agreement with those predicted by Fisher's 1948 vapor nucleation theory. A maximum tension of 140 megapascals (=1400 bars) was reached at 42 degrees C, which lies on an extrapolation of the line of isobaric density maxima. At higher densities, cavitation of droplets that survived heterogeneous nucleation failed to occur at all unless provoked, at much lower temperatures, by freezing. This observation confirms the existence of a density maximum at 42 degrees C and -140 megapascals and hence greatly strengthens the basis for Speedy's conjecture of a reentrant spinodal for water.

Effect of a lipidic extract from lepidium meyenii on sexual behavior in mice and rats

OBJECTIVES

To determine the effect of oral administration of a purified lipidic extract from Lepidium meyenii (MacaPure M-01 and M-02) on the number of complete intromissions and mating in normal mice, and on the latent period of erection (LPE) in rats with erectile dysfunction.

METHODS

Mice and rats were randomly divided into several experimental and control groups. A 10% ethanol suspension of M-01 and M-02 was orally administered for 22 days to the experimental groups according to the dosage specified by the experimental design. On day 22, 30 minutes after the dose was administered to the male mice, 2 virgin female mice were placed with 1 male mouse. The number of complete intromissions of each male mouse in 3 hours was recorded. In an assessment of 1 day of mating, each male mouse was cohabited with 5 estrous female mice overnight. The number of sperm-positive females was recorded. The LPE was measured to assess the sexual function in rats with erectile dysfunction. By using a YSD-4G multifunction instrument, an electric pulse at 20 V was applied to stimulate the rat's penis, and the duration from the start of the stimulus to full erection was measured in seconds as the LPE.

RESULTS

In the normal male mice, the number of complete intromissions during the 3-hour period was 16.33 +/- 1.78, 46.67 +/- 2.39, and 67.01 +/- 2.55 for the control group, M-01 group, and M-02 group, respectively. In the assessment of mating, the number of sperm-positive females increased from 0.6 +/- 0.7 in the control group to 1.5 +/- 0.5 in the M-01 experimental group. The LPE of male rats with erectile dysfunction was 112 +/- 13 seconds with a regular diet (control group). The oral administration of M-01 at a dose of 180 or 1800 mg/kg body weight and M-02 at a dose of 45, 180, or 1800 mg/kg body weight reduced the LPE to 54 +/- 12 seconds, 54 +/- 13 seconds, 71 +/- 12 seconds, 73 +/- 12 seconds, and 41 +/- 13 seconds, respectively. The LPE of the surgical rats treated with M-01 at the lowest dose (45 mg/kg) was 121 +/- 12 seconds; thus, the change was not significant.

CONCLUSIONS

Oral administration of M-01 and M-02 enhanced the sexual function of the mice and rats, as evidenced by an increase in the number of complete intromissions and the number of sperm-positive females in normal mice, and a decrease in the LPE in male rats with erectile dysfunction. The present study reveals for the first time an aphrodisiac activity of L. meyenii, an Andean Mountain herb.

A nuclear-mitochondrial DNA interaction affecting hearing impairment in mice

The pathophysiologic pathways and clinical expression of mitochondrial DNA (mtDNA) mutations are not well understood. This is mainly the result of the heteroplasmic nature of most pathogenic mtDNA mutations and of the absence of clinically relevant animal models with mtDNA mutations. mtDNA mutations predisposing to hearing impairment in humans are generally homoplasmic, yet some individuals with these mutations have severe hearing loss, whereas their maternal relatives with the identical mtDNA mutation have normal hearing. Epidemiologic, biochemical and genetic data indicate that nuclear genes are often the main determinants of these differences in phenotype. To identify a mouse model for maternally inherited hearing loss, we screened reciprocal backcrosses of three inbred mouse strains, A/J, NOD/LtJ and SKH2/J, with age-related hearing loss (AHL). In the (A/J x CAST/Ei) x A/J backcross, mtDNA derived from the A/J strain exerted a significant detrimental effect on hearing when compared with mtDNA from the CAST/Ei strain. This effect was not seen in the (NOD/LtJ x CAST/Ei) x NOD/LtJ and (SKH2/J x CAST/Ei) x SKH2/J backcrosses. Genotyping revealed that this effect was seen only in mice homozygous for the A/J allele at the Ahl locus on mouse chromosome 10. Sequencing of the mitochondrial genome in the three inbred strains revealed a single nucleotide insertion in the tRNA-Arg gene (mt-Tr) as the probable mediator of the mitochondrial effect. This is the first mouse model with a naturally occurring mtDNA mutation affecting a clinical phenotype, and it provides an experimental model to dissect the pathophysiologic processes connecting mtDNA mutations to hearing loss.

Progress of a half century in the study of the Luria-Delbrück distribution

The Luria-Delbrück mutation model has been mathematically formulated in a number of ways. This review article examines four most important formulations, focusing on important practical issues closely linked with the distribution of the number of mutants. These issues include the probability generating functions, moments (cumulants), computational methods and asymptotics. This review emphasizes basic principles which not only help to unify existing results but also allow for a few useful extensions. In addition, the review offers a historical perspective and some new explanations of divergent moments.

Androgen receptor gene CAG repeat length varies in a race-specific fashion in men without prostate cancer

OBJECTIVES

Preliminary studies suggest that black men have shorter androgen receptor CAG repeat length compared with non-Hispanic whites. Because decreased CAG repeat length (in particular less than 20 repeats) may be associated with increased prostate cancer risk, these findings are potentially important in providing a hypothesis to explain the increased risk of prostate cancer in black men.

METHODS

CAG repeat length in the androgen receptor (exon one) was determined by a polymerase chain reaction method in 130 non-Hispanic white and 65 black men. All men had prostate-specific antigen levels less than 4 ng/mL and normal digital rectal examinations. Men self-classified themselves into racial categories by a standardized questionnaire.

RESULTS

For whites, the mean +/- SD, median, and range of CAG repeat length were 21.0+/-3.0, 21, and 9 to 28, respectively. For blacks, the mean +/- SD, median, and range of CAG repeat length were 19.0+/-3.0, 19, and 13 to 26, respectively. The mean and median CAG repeat length in blacks were statistically significantly shorter than in whites. Black men were twice as likely as whites to have fewer than 20 CAG repeats (56.9% versus 28.5%, P = 0.0001).

CONCLUSIONS

These data unequivocally demonstrate that androgen receptor gene CAG repeat length varies in a race-specific manner in men without evidence of prostate cancer.

Comparative cholinergic neurotoxicity of oral chlorpyrifos exposures in preweanling and adult rats

Chlorpyrifos (CPF) is a common organophosphorus (OP) pesticide. Previous studies have demonstrated that neonatal rats are more sensitive than adults to the acute toxicity of high dosages of CPF. The present study examined lethality and age-related differences in neurochemical indicators and functional signs of neurotoxicity following a broad range of acute and repeated oral CPF exposures. There was about a 9-fold difference in sensitivity to the acute-dose lethality of chlorpyrifos among neonatal (7 days-of-age) and adult (90 days-of-age) rats (LD(10): neonates = 15 mg/kg; adults = 136 mg/kg), while juvenile rats (21 days-of-age) exhibited intermediate sensitivity (LD(10) = 47 mg/kg). Neonatal and adult rats (n = 5-7/treatment/age group/time point) were given CPF (0, 0.15, 0.45, 0. 75, 1.5, 4.5, 7.5, or 15 mg/kg/day) for 14 days and sacrificed 4 h after either the first or 14th dose for neurochemical measurements (cholinesterase activity in frontal cortex, plasma and RBC, and muscarinic ([(3)H]QNB) and nicotinic ([(3)H]epibatidine) receptor binding in frontal cortex. No overt signs of functional toxicity (involuntary movements, SLUD signs) were noted in either age group by 4 h after the first dose. With repeated CPF exposures, however, signs of cholinergic toxicity were noted in both age groups at the higher dose levels [no observed effect levels (NOELs): neonate = 4.5 mg/kg/day; adult = 7.5 mg/kg/day]. Similar degrees of ChE inhibition were noted in neonatal brain and blood fractions following acute exposure, but substantial ChE inhibition was only noted in adult plasma and RBC 4 h after the first treatment. Following repeated CPF exposures, similar degrees of ChE inhibition were again noted in tissues from immature animals, but a wide range of sensitivity to inhibition was noted in adult tissues. NOELs based on ChE inhibition for adults were about 1->/=10-fold higher than in neonates with acute exposure but only 0.2-2 times higher with repeated dosing. Moreover, dose-related inhibition of brain ChE was similar between age groups, and similar reductions in both QNB and epibatidine binding were noted between the age groups after repeated dosing, even though by the end of the dosing period young animals (juveniles) were still about 3 times more sensitive than adults, based on acute lethality. We conclude that while immature animals can be markedly more sensitive to lethal effects of high doses of CPF, lesser or no age-related differences are apparent, based on non-lethal endpoints, in particular with repeated exposures.

Mouse mutants from chemically mutagenized embryonic stem cells

The drive to characterize functions of human genes on a global scale has stimulated interest in large-scale generation of mouse mutants. Conventional germ-cell mutagenesis with N-ethyl-N-nitrosourea (ENU) is compromised by an inability to monitor mutation efficiency, strain and interlocus variation in mutation induction, and extensive husbandry requirements. To overcome these obstacles and develop new methods for generating mouse mutants, we devised protocols to generate germline chimaeric mice from embryonic stem (ES) cells heavily mutagenized with ethylmethanesulphonate (EMS). Germline chimaeras were derived from cultures that underwent a mutation rate of up to 1 in 1,200 at the Hprt locus (encoding hypoxanthine guanine phosphoribosyl transferase). The spectrum of mutations induced by EMS and the frameshift mutagen ICR191 was consistent with that observed in other mammalian cells. Chimaeras derived from ES cells treated with EMS transmitted mutations affecting several processes, including limb development, hair growth, hearing and gametogenesis. This technology affords several advantages over traditional mutagenesis, including the ability to conduct shortened breeding schemes and to screen for mutant phenotypes directly in ES cells or their differentiated derivatives.

Invasion and metastasis of hepatocellular carcinoma in relation to urokinase-type plasminogen activator, its receptor and inhibitor

This study was designed to investigate the relationship of urokinase-type plasminogen activator (uPA), uPA receptor (uPAR), and plasminogen activator inhibitor type-1 (PAI-1) to invasion and metastasis of hepatocellular carcinoma (HCC). The expression of uPA, uPAR, and PAI-1 in HCC was determined by immunohistochemistry, Northern blot, and an LCI-D20 nude mouse metastatic model of HCC. The overexpression of uPA, uPAR, and PAI-1 was found in HCC, especially in the patients with portal cancer embolus, tumor invasion, and metastasis. Immunohistochemistry results showed that the rate of positive staining of uPA, uPAR, and PAI-1 were higher in HCC than those in the control groups consisting of cancer-adjacent tissue and normal liver tissue. In the case of HCC invasion, positive uPA and uPAR were seen in 16 and 19 out of 22 patients, respectively (P<0.01 and P<0.001, respectively, as compared with the patients without invasion). In those with portal cancer embolus and tumor metastasis, positive uPAR was eight out of eight and six out of six patients. In those with tumor recurrence, positive uPAR was 15 out of 17 patients (P<0.01 vs. no recurrence). In patients who died within 2 years after surgery, positive uPAR was 12 out of 12 patients (P<0.01 vs. survival), and positive PAI-1 was nine out of 12 patients (P<0.05 vs. survival). In those in which uPA, uPAR, and PAI-1 were all positive staining, stronger cancer invasiveness and higher mortality were found (P<0.05 vs. patients with all negative staining). In 30 patients tested with Northern blot analysis, the results were similar to those tested with immunohistochemistry. Higher expression of uPA mRNA and PAI-1 mRNA were detected in tumor tissues and embolus. In the patients with positive signals of uPA mRNA and PAI-1 mRNA, invasive cases were found in seven out of 19 and eight out of 18 patients, respectively, which were significantly higher than those showing negative signals (P<0.05). In the LCI-D20 nude mouse metastatic model of HCC (MMHCC), PAI-1 activity in plasma and tumor tissue increased with tumor growth, invasion, and metastasis. At an advanced stage of MMHCC, PAI-1 activity rose to 15.4+/-0.7 Au/ml in plasma and 0.8+/-0.3 Au/mg in tumor extracts, which was significantly higher than 6.2+/-1.8 Au/ml in plasma and 0.4+/-0.1 Au/mg in extracts at an early stage (P<0.05). PAI-1 activity related to the changes of serum AFP and tumor progress were r = 0.9544 and r = 0.9648, respectively (P<0.05). The data suggest that the expression of uPA, uPAR, and PAI-1 is increased in HCC, and related to the invasiveness, metastasis, and prognosis of HCC.

mdfw: a deafness susceptibility locus that interacts with deaf waddler (dfw)

The deaf waddler (dfw) mutation is a model system to study the biology of neuroepithelial hearing defects in mice. Here we describe the identification and characterization of a new allele of deaf waddler (dfw2J) and present evidence for a hearing susceptibility locus (mdfw) that interacts with dfw. We found that CBy-dfw2J/dfw2J homozygotes exhibit no discernible auditory brainstem responses (ABR) to sound pressure level stimuli up to 100 dB, indicating a profound deafness. Interestingly, the ABR in CBy-dfw2J/+ heterozygotes is also abnormal, showing age-dependent elevated thresholds characteristic of a progressive hearing loss. When outcrossed onto the CAST/Ei strain, only 24% of the F2 CBy/CAST-dfw2J/ + heterozygotes displayed increased ABR thresholds, suggesting that a second locus, controlling hearing function in dfw2J/+ heterozygotes, was segregating in the CBy/CAST-dfw2J intercross. By linkage analysis, we localized this locus (mdfw) to Chromosome 10, between markers D10Mit127 and D10Mit185, within a 4.0 +/- 1.1 cM genetic interval. All CBy/CAST-dfw2J/+ heterozygotes that develop hearing loss are homozygous for the CBy-derived recessive allele (mdfwC). In contrast, CBy/ CAST-dfw2J/+ heterozygotes expressing even a single copy of the CAST/Ei-derived mdfw allele (Mdfw) retain their normal hearing function. Our results reveal an epistatic relationship between the mdfw and the dfw genes and provide a model system to study nonsyndromic hearing loss in mice.

Identification and characterization of the novel Col10a1 regulatory mechanism during chondrocyte hypertrophic differentiation

The majority of human skeleton develops through the endochondral pathway, in which cartilage-forming chondrocytes proliferate and enlarge into hypertrophic chondrocytes that eventually undergo apoptosis and are replaced by bone. Although at a terminal differentiation stage, hypertrophic chondrocytes have been implicated as the principal engine of bone growth. Abnormal chondrocyte hypertrophy has been seen in many skeletal dysplasia and osteoarthritis. Meanwhile, as a specific marker of hypertrophic chondrocytes, the type X collagen gene (COL10A1) is also critical for endochondral bone formation, as mutation and altered COL10A1 expression are often accompanied by abnormal chondrocyte hypertrophy in many skeletal diseases. However, how the type X collagen gene is regulated during chondrocyte hypertrophy has not been fully elucidated. We have recently demonstrated that Runx2 interaction with a 150-bp mouse Col10a1 cis-enhancer is required but not sufficient for its hypertrophic chondrocyte-specific reporter expression in transgenic mice, suggesting requirement of additional Col10a1 regulators. In this study, we report in silico sequence analysis of this 150-bp enhancer and identification of its multiple binding factors, including AP1, MEF2, NFAT, Runx1 and TBX5. Using this enhancer as bait, we performed yeast one-hybrid assay and identified multiple candidate Col10a1-interacting genes, including cyclooxygenase 1 (Cox-1) and Cox-2. We have also performed mass spectrometry analysis and detected EF1-alpha, Fus, GdF7 and Runx3 as components of the specific complex formed by the cis-enhancer and nuclear extracts from hypertrophic MCT (mouse chondrocytes immortalized with large T antigen) cells that express Col10a1 abundantly. Notably, some of the candidate genes are differentially expressed in hypertrophic MCT cells and have been associated with chondrocyte hypertrophy and Runx2, an indispensible Col10a1 regulator. Intriguingly, we detected high-level Cox-2 expression in hypertrophic MCT cells. Electrophoretic mobility shift assay and chromatin immunoprecipitation assays confirmed the interaction between Cox-2 and Col10a1 cis-enhancer, supporting its role as a candidate Col10a1 regulator. Together, our data support a Cox-2-containing, Runx2-centered Col10a1 regulatory mechanism, during chondrocyte hypertrophic differentiation.

Overexpression of ribosomal RNA in prostate cancer is common but not linked to rDNA promoter hypomethylation

Alterations in nucleoli, including increased numbers, increased size, altered architecture and increased function are hallmarks of prostate cancer cells. The mechanisms that result in increased nucleolar size, number and function in prostate cancer have not been fully elucidated. The nucleolus is formed around repeats of a transcriptional unit encoding a 45S ribosomal RNA (rRNA) precursor that is then processed to yield the mature 18S, 5.8S and 28S RNA species. Although it has been generally accepted that tumor cells overexpress rRNA species, this has not been examined in clinical prostate cancer. We find that indeed levels of the 45S rRNA, 28S, 18S and 5.8S are overexpressed in the majority of human primary prostate cancer specimens as compared with matched benign tissues. One mechanism that can alter nucleolar function and structure in cancer cells is hypomethylation of CpG dinucleotides of the upstream rDNA promoter region. However, this mechanism has not been examined in prostate cancer. To determine whether rRNA overexpression could be explained by hypomethylation of these CpG sites, we also evaluated the DNA methylation status of the rDNA promoter in prostate cancer cell lines and the clinical specimens. Bisulfite sequencing of genomic DNA revealed two roughly equal populations of loci in cell lines consisting of those that contained densely methylated deoxycytidine residues within CpGs and those that were largely unmethylated. All clinical specimens also contained two populations with no marked changes in methylation of this region in cancer as compared with normal. We recently reported that MYC can regulate rRNA levels in human prostate cancer; here we show that MYC mRNA levels are correlated with 45S, 18S and 5.8S rRNA levels. Further, as a surrogate for nucleolar size and number, we examined the expression of fibrillarin, which did not correlate with rRNA levels. We conclude that rRNA levels are increased in human prostate cancer, but that hypomethylation of the rDNA promoter does not explain this increase, nor does hypomethylation explain alterations in nucleolar number and structure in prostate cancer cells. Rather, rRNA levels and nucleolar size and number relate more closely to MYC overexpression.

Meta-analysis of the need for nasogastric or nasojejunal decompression after gastrectomy for gastric cancer

BACKGROUND

Nasogastric or nasojejunal decompression has been used routinely to prevent anastomotic leakage, hasten the return of bowel function and shorten hospital stay after gastrectomy for gastric cancer. This meta-analysis evaluates the necessity for such routine decompression.

METHODS

Medline, Embase and The Cochrane Library were searched. Only prospective randomized controlled trials (RCTs) that compared individuals with and without nasogastric or nasojejunal decompression after gastrectomy for gastric cancer were included. Outcomes evaluated were time to flatus, time to starting oral diet, anastomotic leakage, pulmonary complications, length of hospital stay, and morbidity and mortality.

RESULTS

Of 717 patients in five RCTs, 361 were allocated to nasogastric or nasojejunal decompression and 356 to no decompression. Time to oral diet was significantly shorter in the latter group (weighted mean difference 0.43 (95 per cent confidence interval 0.23 to 0.62) days; P < 0.001). Time to flatus, anastomotic leakage, pulmonary complications, length of hospital stay, morbidity and mortality were similar in both groups.

CONCLUSION

Routine nasogastric or nasojejunal decompression is unnecessary after gastrectomy for gastric cancer.

Oxidative stress in aging in the C57B16/J mouse cochlea

Presbycusis is a complex of high frequency hearing loss and disproportionate loss of speech discrimination that is seen concomitantly with physical signs of aging. Among the most extensively characterized strains of mice that show an early hearing loss is the C57B16/J strain, a strain that shows early onset of high frequency hearing loss at age 6 months and complete hearing loss by 1 year of age. The histopathology of this strain consists of loss of hair cells and spiral ganglion neurons in the basal turn, with a progression of loss of hair cells and ganglion neurons towards the apical portion of the cochlea as the animal ages. The process of aging has been extensively studied and although details differ in various organisms the consensus today is that oxidative stress, i.e. free radical-mediated tissue damage, is one of the core mechanisms of aging. Aerobic metabolism results in the creation of hydrogen peroxide and reactive oxygen species. These are normally detoxified by a variety of enzymes and free radical scavengers, including superoxide dismutase (SOD), catalase and glutathione. To determine whether oxidative stress plays a role in the pathophysiology of hearing loss in this mouse model of presbycusis we determined the relative change in mRNA production for selected free radical detoxifying enzymes in the C57B16/J mouse cochlea. Using semi-quantitative RT-PCR with tubulin mRNA as a control, relative levels of antioxidant enzyme mRNAs were determined. There was an overall increase in SOD1 mRNA levels when comparing 1 and 9 month time points, and a transient increase in the expression level of catalase mRNA. B6.CAST+ Ahl mice, which carry the C57B16/J genome but receive their Ahl gene from CAST mice, do not show these alteractions in antioxidant enzyme production. Our results suggest that at an age of 9 months, at which point significant hearing loss has developed, the C57B16/J mouse cochlea is exposed to increased levels of free radicals and that the Ahl gene of the C57B16/J mouse mediates this decrease in protective enzymes and therefore increase in levels of oxidative stress.

Biomarker risk assessment and bladder cancer detection in a cohort exposed to benzidine

BACKGROUND

Cancer screening with highly sensitive, specific biomarkers that reflect molecular phenotypic alterations is an attractive strategy for cancer control. We examined whether biomarker profiles could be used for risk assessment and cancer detection in a cohort of Chinese workers occupationally exposed to benzidine and at risk for bladder cancer.

METHODS

The cohort consisted of 1788 exposed and 373 nonexposed workers, followed from 1991 through 1997. We assayed urothelial cells from voided urine samples for DNA ploidy (expressed as the 5C-exceeding rate [DNA 5CER]), the bladder tumor-associated antigen p300, and a cytoskeletal protein (G-actin). Workers were stratified into different risk groups (high, moderate, and low risk) at each examination based on a predefined biomarker profile. For workers who developed bladder cancer, tumor risk assessment was analyzed from samples collected 6-12 months before the cancer diagnosis. The associations between risk group and subsequent development of bladder cancer were analyzed by Cox proportional hazards regression analysis and logistic analysis, after adjustment. All statistical tests were two-sided.

RESULTS

Twenty-eight bladder cancers were diagnosed in exposed workers and two in nonexposed workers. For risk assessment, DNA 5CER had 87.5% sensitivity, 86.5% specificity, an odds ratio (OR) of 46.2 (95% confidence interval [CI] = 8.1 to 867.0), and a risk ratio (RR) of 16.2 (95% CI = 7.1 to 37.0); p300 had 50.0% sensitivity, 97.9% specificity, an OR of 40.0 (95% CI = 9.0 to 177.8), and an RR of 37.9 (95% CI = 16.8 to 85.3). The risk of developing bladder cancer was 19.6 (95% CI = 8.0 to 47.9) times higher in workers positive for either the DNA 5CER or p300 biomarkers than in workers negative for both biomarkers and 81.4 (95% CI = 33.3 to 199.3) times higher in workers positive for both biomarkers. G-actin was a poor marker of individual risk.

CONCLUSIONS

Occupationally exposed workers at risk for bladder cancer can be individually stratified, screened, monitored, and diagnosed based on predefined molecular biomarker profiles.

Heterogeneous to homogeneous melting transition visualized with ultrafast electron diffraction

The ultrafast laser excitation of matters leads to nonequilibrium states with complex solid-liquid phase-transition dynamics. We used electron diffraction at mega-electron volt energies to visualize the ultrafast melting of gold on the atomic scale length. For energy densities approaching the irreversible melting regime, we first observed heterogeneous melting on time scales of 100 to 1000 picoseconds, transitioning to homogeneous melting that occurs catastrophically within 10 to 20 picoseconds at higher energy densities. We showed evidence for the heterogeneous coexistence of solid and liquid. We determined the ion and electron temperature evolution and found superheated conditions. Our results constrain the electron-ion coupling rate, determine the Debye temperature, and reveal the melting sensitivity to nucleation seeds.

Network meta-analysis of novel and conventional sentinel lymph node biopsy techniques in breast cancer

Background

The aim of this network meta‐analysis was to compare the performance of blue dye alone or in combination with radioisotope (technetium‐99m, Tc) with three novel techniques for sentinel lymph node detection in breast cancer: indocyanine green fluorescence (ICG), superparamagnetic iron oxide (SPIO) nanoparticles and contrast‐enhanced ultrasound imaging (CEUS).

Methods

PubMed, Embase, the Cochrane Library, China Knowledge Research Integrated Database, ClinicalTrials.gov and OpenGrey databases were searched up to 31 November 2017, without language restriction. Studies that compared the detection performance of at least one of the novel methods (ICG, SPIO and CEUS) with that of traditional methods (blue dye and/or radioisotope) were included in network meta‐analysis.

Results

Thirty‐five studies were included. Pooled risk ratios (RRs) for Tc (1·09, 95 per cent c.i. 1·04 to 1·15), ICG (1·12, 1·07 to 1·16) and SPIO (1·09, 1·01 to 1·18) showed statistically better performance in detecting sentinel lymph nodes than blue dye alone. ICG had the lowest false‐negative rate, with a RR of 0·29 (0·16 to 0·54), followed by Tc (RR 0·44, 0·20 to 0·96) and SPIO (RR 0·45, 0·14 to 1·45), with blue dye alone as the reference group.

Conclusion

SPIO or ICG alone are superior to blue dye alone and comparable to the standard dual‐modality technique of blue dye with Tc.