Acoustic performance of near-rail low-height noise barriers installed on suburban railway bridges.

With the large-scale construction of suburban railway viaducts, the noise problem along the viaducts is becoming more and more prominent. Conventional vertical noise barriers have been widely used to alleviate the noise problem along the suburban railway viaducts. However, conventional vertical noise barriers often have an adverse effect on the urban landscape and also block the view of train drivers and passengers. A type of near-rail low-height noise barrier was planned to install on the viaducts of Wenzhou Rail Transit Line S1 to reduce the impact of noise on residents along the railway lines. To assess the acoustic performance of the near-rail low-height noise barrier, a numerical procedure for railway viaduct comprehensive noise considering wheel-rail noise and structure-borne noise of the bridge and noise barriers was proposed and then verified by a field test. On this basis, numerical models were established to compare the acoustic performances of the near-rail low-height noise barrier and conventional vertical noise barrier. The influences of the height and top shape of the near-rail low-height noise barrier on the acoustic performance were discussed. Based on the numerical analysis results, it is found that both the near-rail low-height noise barrier and conventional vertical noise barrier have good acoustic performances. The noise reduction effect of the near-rail low-height noise barrier is slightly better than that of the conventional vertical noise barrier. The acoustic performance of the near-rail low-height noise barrier gradually improves, but the improvement rate gradually slows down as the height of the noise barrier increases. The noise reduction effects of both the inverted L-shaped and Y-shaped near-rail low-height noise barrier are obviously better than that of the vertical one, while the noise reduction effects of the inverted L-shaped near-rail low-height noise barrier are slightly better than the Y-shaped one.

The Diagnosis of Choriocarcinoma in Molar Pregnancies: A Revised Approach in Clinical Testing.

BACKGROUND: Hydatidiform moles occur in approximately 1 in 1,500 pregnancies; however, early miscarriages or spontaneous abortions may not be correctly identified as molar pregnancies due to poor differentiation of chorionic villi. METHODS: The current clinical testing algorithm used for the detection of hydatidiform moles uses a combination of morphological analysis and p57 immunostaining followed by ploidy testing to establish a diagnosis of either a complete or partial molar pregnancy. We review here 198 referrals for fluorescence in situ hybridization (FISH) ploidy testing, where the initial diagnosis based on morphology is compared to the final diagnosis based on a combination of morphology, FISH and p57 immunohistochemical (IHC) staining. RESULTS: Approximately 40% of cases were determined to be genetically abnormal, but only 28.8% of cases were diagnosed as molar pregnancies. The underestimation of complete molar pregnancies and those with androgenetic inheritance was also found to be likely using conventional diagnostic methods, as atypical p57 staining was observed in approximately 10% of cases. CONCLUSIONS: Our findings suggest that a revised approach to testing products of conception is necessary, with cases screened according to their clinical history in order to distinguish molar pregnancy referrals from hydropic pregnancies.

Molecular characterisation of phenylketonuria in a Chinese mainland population using next-generation sequencing.

Phenylketonuria (PKU) is an inherited autosomal recessive disorder of phenylalanine metabolism, mainly caused by a deficiency of phenylalanine hydroxylase (PAH). The incidence of various PAH mutations differs among race and ethnicity. Here we report a spectrum of PAH mutations complied from 796 PKU patients from mainland China. The all 13 exons and adjacent intronic regions of the PAH gene were determined by next-generation sequencing. We identified 194 different mutations, of which 41 are not reported before. Several mutations reoccurred with high frequency including p.R243Q, p.EX6-96A > G, p.V399V, p.R241C, p.R111*, p.Y356*, p.R413P, and IVS4-1G > A. 76.33% of mutations were localized in exons 3, 6, 7, 11, 12. We further compared the frequency of each mutation between populations in northern and southern China, and found significant differences in 19 mutations. Furthermore, we identified 101 mutations that are not reported before in Chinese population, our study thus broadens the mutational spectrum of Chinese PKU patients. Additionally, 41 novel mutations will expand and improve PAH mutation database. Finally, our study offers proof that NGS is effective, reduces screening times and costs, and facilitates the provision of appropriate genetic counseling for PKU patients.

Microduplication of 3p26.3 implicated in cognitive development.

We report here a 34-month-old boy with global developmental delay referred for molecular karyotyping and fragile X studies. Molecular karyotype analysis revealed a microduplication in the 3p26.3 region involving part of the CHL1 and CNTN6 genes. Several deletions, one translocation, and one duplication have previously been described in this region of chromosome 3. The CHL1 gene has been proposed as a dosage-sensitive gene with a central role in cognitive development, and so the microduplication reported here appears to be implicated in our patient's phenotype.

Array comparative genomic hybridization identifies a heterozygous deletion of the entire KCNJ2 gene as a cause of sudden cardiac death.

BACKGROUND: Large gene rearrangements, not detectable by standard molecular genetic sequencing techniques, are present in a minority of patients with long QT syndrome. We aimed to screen for large rearrangements in genes responsible for long QT syndrome as part of the molecular autopsy of a 36-year-old woman who died suddenly and had a negative autopsy. A retrospective analysis of an ECG identified a long QT interval, but sequencing of known LQT genes was uninformative. METHODS AND RESULTS: Array comparative genomic hybridization was used to screen for deletions and duplications in 101 genes implicated in cardiac disorders and sudden death using a postmortem blood sample. A 542 kb deletion encompassing the entire KCNJ2 gene was identified in the decedent. The mother had electrocardiographic U-wave changes consistent with Andersen-Tawil syndrome and exaggerated by exercise but none of the characteristic noncardiac features. Fluorescence in situ hybridization confirmed the deletion in the decedent and established its presence in the mother. CONCLUSIONS: A novel application of array comparative genomic hybridization and fluorescence in situ hybridization has identified that long QT syndrome and sudden cardiac death may occur as a result of a deletion of an entire gene. The case also supports recent research suggesting that noncardiac features of Andersen-Tawil syndrome occur only with missense or minor gene rearrangements in the KCNJ2 gene, resulting in a dominant negative effect on Kir2.x channels.

Characteristics of fatty acid distribution is associated with colorectal cancer prognosis.

To investigate tissue fatty acid distribution in relation to the incidence of colorectal cancer prognosis, adjacent normal tissue and cancerous tissue from 35 samples of clinically incident colorectal cancer were obtained. Fatty acids were measured in the colorectal mucosa phospholipid fraction by gas chromatography mass spectrometry. Palmitoleic acid and oleic acid were significantly lower in colorectal cancerous tissue, ranging from 20% to 50% less than the adjacent normal tissue. The omega-6 (n-6) fatty acid family members (20:2, 20:3, 20:4 and 22:4) were higher by 1-3 fold in cancerous colorectal tissue. Contrary with the high level of n-6 fatty acids, about a 37% to 87% reduction in EPA and DHA was observed in colorectal cancerous tissue. A higher level of linoleic acid and arachidonic acid was detected in the C cancer stage than in the B cancer stage (p<0.05), but a lower level of oleic acid and docosahexenoic acid was detected in the C cancer stage (p<0.05). The fatty acid distribution of colorectal tissue is strongly linked to the incidence of colorectal cancer. This study also provides scientific basis for identifying novel biomarkers for the diagnosis and treatment of cancer.

Quantification of the sixth DNA base 5-hydroxymethylcytosine in colorectal cancer tissue and C-26 cell line.

BACKGROUND: DNA methylation at the five position of cytosine is well recognized as an important epigenetic modification in human health and disease. Recent evidences demonstrated that 5-methylcytosine (5-mC) by the TET family of enzymes can be converted to 5-hydroxymethylcytosine (5-hmC). Here, we use an ultrasensitive and accurate isotope-based LC-MS/MS method to precisely determine the levels of 5-hmC and 5-mC in colorectal cancer and the C-26 colon adenocarcinoma cell line. RESULTS: Our data showed that 5-hmC content is significantly reduced (approximately sixfold) in colorectal cancer as compared with adjacent normal tissue. Similarly, the ratio of 5-hmC to 5-mC dropped from 0.054 ± 0.005 in normal tissues, to 0.011 ± 0.002 in cancer. CONCLUSION: The analysis of 5-hmC levels and the ratio of 5-hmC:5-mC during tumor progression might provide insight into the role of this modification in cellular immortalization and transformation.

[Analysis of global deoxyribonucleic acid 5-hydroxymethylcytosine in tissue by liquid chromatography-tandem mass spectrometry].

As preventing deoxyribonucleic acid (DNA) methylation transferase 1 (DNMT1) methylation of the target cytosine, 5-hydroxymethylcytosine could cause alterations in DNA methylation. A rapid analytical method for the determination of the degree of global DNA hydroxymethylation in tissues using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed. After the extraction with phenol-chloroform, DNA was hydrolyzed to nucleobases by 88% formic acid at 140 degrees C, dried under nitrogen, followed by spiking with cytosine-13C15SN2 as internal standard, and reconstituted in a mixture of acetonitrile-water (9:1, v/v) for the analysis with LC-MS/MS. The LC separation was performed on a BEH HILIC column (100 mm x 2.1 mm, 1.7 microm) by gradient elution with 10 mmol/L ammonium acetate and acetonitrile as mobile phases. The analytes were detected by MS/MS with positive ion electrospray ionization (ESI+) in multiple reaction monitoring (MRM) mode to satisfy qualitative and quantitative detections. The results showed that the linear range of the calibration curve for 5-hydroxymethylcytosine was 0.1-30 ng/mL, and the correlation coefficient was higher than 0.99. The limit of detection (LOD, S/N = 3) and the limit of quantification (LOQ, S/N = 10) were 0.057 and 0.090 ng/mL, respectively. The intraday and interday precisions were 5.13% and 6.24%, respectively. The recoveries of the spiked standards varied from 90.24% to 97.53%. The method was applied to the analysis of DNA from cerebrums of rats, and the average degree of 5-hydroxymethylcytosine was 0.66%. The method is simple, reproducible, sensitive and suitable for the quantitative analysis of 5-hydroxymethylcytosine in global DNA from tissues.

Simultaneous determination of global DNA methylation and hydroxymethylation levels by hydrophilic interaction liquid chromatography-tandem mass spectrometry.

Methylation of DNA at the 5-position of cytosine (Cyt) is a well-studied epigenetic pathway implicated in gene silencing and embryogenesis. Recently, in addition to 5-methylcytosine (5mC), substantial amounts of 5-hydroxymethylcytosine (5hmC) have been detected in certain mammalian tissues. Here, we developed and validated a hydrophilic interaction liquid chromatography-tandem mass spectrometry (HILIC-MS/MS) method for the simultaneous determination of Cyt, 5mC, and 5hmC levels in biological samples. DNA was extracted with phenol-chloroform, hydrolyzed using 88% formic acid at 140 °C, separated using a bridged ethylene hybrid HILIC column, and analyzed by tandem MS. The linearity was established over the concentration range of 1 to 500 ng/mL for Cyt, 0.2 to 100 ng/mL for 5mC, and 0.1 to 50 ng/mL for 5hmC, and the correlation coefficients were all >0.99. Limits of detection were 1 pg/mL for Cyt, 45 pg/mL for 5mC, and 57 pg/mL for 5hmC, and the limit of quantification values for Cyt, 5mC, and 5hmC were 2 pg/mL, 90 pg/mL, and 100 pg/mL, respectively. The relative standard deviation (RSD) of the intraday precision ranged from 1.87% to 4.84% and the interday precision from 2.69% to 4.98%. The recovery of the method varied from 88.25% to 104.39%. The method was then applied to the analysis of DNA from biological samples, establishing its potential for helping researchers understand the roles of modified nucleobases in DNA.

[Determination of global DNA methylation in tissues by hydrophilic interaction liquid chromatography].

A hydrophilic interaction liquid chromatographic (HILIC) method has been developed for the determination of global DNA methylation in tissues. The DNA was extracted by phenol-chloroform, hydrolyzed with 88% formic acid at 140 degrees C, evaporated under nitrogen at 60 degrees C, and reconstituted in a mixture of acetonitrile/water (90:10, v/v); the separation was achieved on a Waters bridged ethylene hybrid (BEH) HILIC column (100 mm x 2.1 mm, 1.7 microm). The cytosine (Cyt) and 5-methylcytosine (5-mCyt) were separated in a fairly short time (3.5 min) by isocratic elution with a mixture of acetonitrile/10 mmol/L ammonium formate (94:6, v/v) as the mobile phase. Under the optimized conditions, calibration standard curve showed a good linearity in the range 1-900 micromol/L for Cyt and in the range 1-64 micromol/L for 5-mCyt with correlation coefficients of 0.9999 and 0.9998, respectively. The limit of detection (LOD) was 54 nmol/L (0.54 pmol on-column) both for Cyt and 5-mCyt, and the limit of quantification was 250 nmol/L (2.5 pmol on-column) both for Cyt and 5-mCyt. The recoveries of Cyt at the spiked levels of 90, 450, 900 micromol/L and 5-mCyt at the spiked levels of 5, 16, 64 micromol/L all ranged from 94.7% to 100.5% with a relative standard deviations less than 1.48%. The method was applied to the analysis of DNA from colon cancer tissue, and the average degree of methylation was 4.0%. The method is rapid, simple, sensitive, reliable, and suitable for the determination of global DNA methylation.

Analysis of global DNA methylation by hydrophilic interaction ultra high-pressure liquid chromatography tandem mass spectrometry.

We developed and validated a rapid, sensitive, and specific liquid chromatography tandem mass spectrometry (LC-MS/MS) method for determination of global DNA methylation in tissue. DNA was extracted by phenol-chloroform, hydrolyzed using 88% formic acid at 140°C, spiked with cytosine-2,4-(13)C(15)N(2) as internal standard, evaporated under nitrogen, reconstituted in methanol, and analyzed by LC-MS/MS in multiple reaction monitoring mode to reflect the global DNA methylation of the tissue. The method was linear throughout the range of clinical interest and had good sensitivity, with a limit of quantification of 0.5pg for both cytosine (Cyt) and 5-methylcytosine (5mCyt). The linear range of calibration curve was 1-50 and 1-100ng/ml for 5mCyt and Cyt, respectively, with a correlation coefficient higher than 0.99. The relative standard deviation (RSD) was 0.70-4.09% and 0.60-4.81% for Cyt and 5mCyt, respectively. The intraday precision expressed as RSD ranged from 1.86% to 4.67%, whereas the interday values ranged from 3.72% to 4.68%. The recovery of the method varied from 86.52% to 105.14%. This yielded a simple and reliable LC-MS/MS assay for detection of Cyt and 5mCyt, thereby enabling the evaluation of global DNA methylation.

Variable patterns of chromosome synapsis at pachytene in Hordeum vulgare x H. bulbosum hybrids and their parents.

Synaptonemal complexes (SC) have been analysed in barley (Hordeum vulgare), H. bulbosum and two F, hybrids between them. These hybrids show different recombination frequencies and at pachytene show significant differences in the total length of SC formed and in the extent of synapsis. Higher recombination frequency in the hybrids was correlated with a greater total SC length. Differences in SC length were also observed between the parental species with H. bulbosum having a greater SC length than H. vulgare. However, species and hybrid can have similar SC lengths but clearly different recombination frequencies and, therefore, the relationship between SC length and recombination is not clear-cut.