The rs4238326 polymorphism in ALDH1A2 gene potentially associated with non-post traumatic knee osteoarthritis susceptibility: a two-stage population-based study

OBJECTIVE

A recent genome-wide association study reported significant associations of genetic variants within the ALDH1A2 gene with osteoarthritis (OA) of the hand in European populations. However, these findings have not been well generalized to other joints, or to other populations.

METHODS

We performed a two-stage population-based case-control study including 196 non-post traumatic knee OA cases and 442 controls in the first stage and independent 143 non-post traumatic knee OA cases and 238 controls in the second stage in a Chinese population by genotyping eight tagging polymorphisms in ALDH1A2.

RESULTS

In the first stage, the single nucleotide polymorphism (SNP) rs4238326 was found to be potentially associated with knee OA risk (additive model: odds ratio [OR] = 0.70; 95% confidence interval [95% CI] = 0.49-1.01; P = 0.055), which was further confirmed in the second stage with similar effect (additive model: OR = 0.60; 95% CI = 0.38-0.95; P = 0.029). After combining the two stages, we found that the variant C allele of rs4238326 was probably associated with decreased risk of knee OA (additive model: OR = 0.65; 95% CI = 0.49-0.86; P = 0.003). Furthermore, interaction analyses showed that rs4238326 interacted multiplicatively with age to contribute to knee OA risk (interaction P = 0.041).

CONCLUSIONS

These findings indicate that the SNP rs4238326 in ALDH1A2 gene may potentially modify individual susceptibility to knee OA in the Chinese population. Beyond that, further studies are warranted to validate and extend our findings, and future functional studies are required to clarify the possible mechanisms.

Long-term response in patient with recurrent oropharyngeal carcinoma treated with cetuximab, docetaxel and cisplatin (TPEx) as first-line treatment followed by cetuximab maintenance

BACKGROUND

Cetuximab, an anti-EGFR monoclonal antibody in combination with platinum and 5FU is the standard of care in first-line treatment of patients with recurrent head and neck squamous cell carcinoma (HNSCC), with an expected median outcome of 10months. For this population, development of efficacious and safer therapies is still needed.

CASE REPORT

A 62-year-old male with a first recurrence of human papillomavirus positive stage IVA (T3N2bM0) adenocarcinoma of the glossotonsillar sulcus not amenable to locoregional curative treatment was offered chemotherapy as part of the TPEx clinical trial. He was treated by cetuximab (loading dose 400mg/m² on day 1 cycle 1, then 250mg/m² weekly), and chemotherapy (cisplatin 75mg/m² and docetaxel 75mg/m², on day 1). Cycles were repeated every 21days for 4 cycles (TPEx regimen) with systematic granulocyte colony-stimulating factor support at each cycle. Bi-monthly maintenance cetuximab 500mg/m² was then administered. The patient showed a clinical complete response according to RECIST 1.1 criteria after 5months maintenance, with progression-free survival of 25months. Relapses that followed were treated with stereotactic irradiation, radiofrequency ablation, cetuximab and paclitaxel. The patient is alive eleven years after cancer diagnosis and remains controlled for his disease, with a cumulative period of 59months of cetuximab administration (equivalence of 121 injections).

CONCLUSION

This case report demonstrated that TPEx regimen, by synergistic interaction between taxanes and cetuximab, followed by bimonthly cetuximab maintenance may lead to patient complete remission within the first year of treatment. Furthermore, prolonged intermittent treatment with cetuximab seems to participate in the improved survival associated with preserved quality of life. Key favorable prognostic factors may be moderate tumor differentiation, oropharyngeal location, HPV p16 positive tumor status.

Temporal model for quasi-phase matching in high-order harmonic generation

We present a model for quasi-phase matching (QPM) in high-order harmonic generation (HHG). Using a one-dimensional description, we analyze the time-dependent, ultrafast wave-vector balance to calculate the on-axis harmonic output versus time, from which we obtain the output pulse energy. Considering, as an example, periodically patterned argon gas, as may be provided with a grid in a cluster jet, we calculate the harmonic output during different time intervals within the drive laser pulse duration. We find that identifying a suitable single spatial period is not straightforward due to the complex and ultrafast plasma dynamics that underlies HHG at increased intensities. The maximum on-axis harmonic pulse energy is obtained when choosing the QPM period to phase match HHG at the leading edge of the drive laser pulse.

Abstract PD8-03: Differences in the mutational landscape in African Americans and Caucasians with triple negative breast cancer

Background-Triple negative breast cancer (TNBC) occurs at a higher frequency in African American (AA) premenopausal women compared with Caucasians. It is unclear if the biology and clinical outcome of TNBC is different in AA versus Caucasians. In this study, we sought to evaluate differences in the molecular pathology of TNBC in a large cohort of AA and Caucasians.

Methods-Using publicly available data from The Cancer Genome Atlas, we identified all patients with TNBC who had information on race. We analyzed the differences in clinical characteristics and tumor somatic mutations by race from whole exome sequencing using student's t test or one-way ANOVA for continuous variables and chi square or Fisher's test for categorical variables. Exome sequencing was performed with coverage of ≥70% and at a depth of 20x.

Results-A total of 1104 primary breast cancer patients were identified, of which 178 (16%) had TNBC. Overall, TNBC was more frequent in AA than in Caucasians (33.3% versus 14.9%; p value <0.001). More AA than Caucasians were classified as basal-like from PAM50 gene expression analysis (34.8% versus 16.1%; p value 0.001). No differences in the TNBC cohort were observed, 91% of AA were basal-like versus 81% of Caucasians (p value 0.842). Median tumor somatic mutation counts were higher in AA (39.5) versus Caucasians (34) (p value 0.022). However, no racial differences in the mutation counts in TNBC were observed (AA=56, Caucasians=60, p value 0.399). Somatic mutation analysis revealed racial differences in specific high prevalence (>5%) genes in all patients- [TP53 alterations: 46% in AA versus 27% in Caucasians; p value <0.001, PIK3CA alterations: 23% in AA versus 34% in Caucasians; p value 0.019, and MLL3 alterations: 12% in AA versus 6% in Caucasians; p value 0.028]. The TNBC patients did not have any specific high prevalence (>5%) genes associated with racial differences. AA with breast cancer had a shorter time to progression (TTP) (hazard ratio 1.62, p value 0.014) and worse disease free survival (DFS) than Caucasians. However, racial difference in TTP or DFS were not observed in the TNBC patients.

Conclusion-The mutational landscape of breast cancer may be different between AA and Caucasians, but appears to be similar in both races in the cohort with TNBC. Our findings have 2 implications: racial disparities in breast cancer may largely be due to differences in those with hormone receptor positive disease, and secondly, the higher frequency of TNBC in AA is unlikely due to differences in molecular features, but other modifiable factors.

Citation Format: Ademuyiwa FO, Tao Y, Luo J. Differences in the mutational landscape in African Americans and Caucasians with triple negative breast cancer [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr PD8-03.

Quantitative chemoproteomic profiling reveals multiple target interactions of spongiolactone derivatives in leukemia cells

Identifying the covalent targets of a natural product-derivative in cancer cells.

Ultrasensitive mechanical detection of magnetic moment using a commercial disk drive write head

Sensitive detection of weak magnetic moments is an essential capability in many areas of nanoscale science and technology, including nanomagnetism, quantum readout of spins and nanoscale magnetic resonance imaging. Here we show that the write head of a commercial hard drive may enable significant advances in nanoscale spin detection. By approaching a sharp diamond tip to within 5 nm from a write pole and measuring the induced diamagnetic moment with a nanomechanical force transducer, we demonstrate a spin sensitivity of 0.032 μB Hz(-1/2), equivalent to 21 proton magnetic moments. The high sensitivity is enabled in part by the pole's strong magnetic gradient of up to 28 × 10(6) T m(-1) and in part by the absence of non-contact friction due to the extremely flat writer surface. In addition, we demonstrate quantitative imaging of the pole field with ∼10 nm spatial resolution. We foresee diverse applications for write heads in experimental condensed matter physics, especially in spintronics, ultrafast spin manipulation and mesoscopic physics.

eEF-2 kinase is a critical regulator of Warburg effect through controlling PP2A-A synthesis

Cancer cells predominantly metabolize glucose by glycolysis to produce energy in order to meet their metabolic requirement, a phenomenon known as Warburg effect. Although Warburg effect is considered a peculiarity critical for survival and proliferation of cancer cells, the regulatory mechanisms behind this phenomenon remain incompletely understood. We report here that eukaryotic elongation factor-2 kinase (eEF-2K), a negative regulator of protein synthesis, has a critical role in promoting glycolysis in cancer cells. We showed that deficiency in eEF-2K significantly reduced the uptake of glucose and decreased the productions of lactate and adenosine triphosphate in tumor cells and in the Ras-transformed mouse embryonic fibroblasts. We further demonstrated that the promotive effect of eEF-2K on glycolysis resulted from the kinase-mediated restriction of synthesis of the protein phosphatase 2A-A (PP2A-A), a key factor that facilitates the ubiquitin-proteasomal degradation of c-Myc protein, as knockdown of eEF-2K expression led to a significant increase in PP2A-A protein synthesis and remarkable downregulation of c-Myc and pyruvate kinase M2 isoform, the key glycolytic enzyme transcriptionally activated by c-Myc. In addition, depletion of eEF-2K reduced the ability of the transformed cells to proliferate and enhanced the sensitivity of tumor cells to chemotherapy both in vitro and in vivo. These results, which uncover a role of the eEF-2K-mediated control of PP2A-A in tumor cell glycolysis, provide new insights into the regulation of the Warburg effect.

Effects of missense mutations in sortase A gene on enzyme activity in Streptococcus mutans

Background

Streptococcus mutans (S. mutans) is the major aetiological agent of dental caries, and the transpeptidase Sortase A (SrtA) plays a major role in cariogenicity. The T168G and G470A missense mutations in the srtA gene may be linked to caries susceptibility, as demonstrated in our previous studies. This study aimed to investigate the effects of these missense mutations of the srtA gene on SrtA enzyme activity in S. mutans.

Methods

The point mutated recombinant S.mutans T168G and G470A sortases were expressed in expression plasmid pET32a. S. mutans UA159 sortase coding gene srtA was used as the template for point mutation. Enzymatic activity was assessed by quantifying increases in the fluorescence intensity generated when a substrate Dabcyl-QALPNTGEE-Edans was cleaved by SrtA. The kinetic constants were calculated based on the curve fit for the Michaelis-Menten equation.

Results

SrtA_{△N40(UA159)} and the mutant enzymes, SrtA_△N40(D56E) and SrtA_{△N40(R157H)}, were expressed and purified. A kinetic analysis showed that the affinity of SrtA_△N40(D56E) and SrtA_{△N40(R157H)} remained approximately equal to the affinity of SrtA_{△N40(UA159)}, as determined by the Michaelis constant (K_m). However, the catalytic rate constant (k_cat) and catalytic efficiency (k_cat/K_m) of SrtA_△N40(D56E) were reduced compared with those of SrtA_{△N40(R157H)} and SrtA_{△N40(UA159)}, whereas the k_cat and k_cat/K_m values of SrtA_{△N40(R157H)} were slightly lower than those of SrtA_{△N40(UA159)}.

Conclusions

The findings of this study indicate that the T168G missense mutation of the srtA gene results in a significant reduction in enzymatic activity compared with S. mutans UA159, suggesting that the T168G missense mutation of the srtA gene may be related to low cariogenicity.

Electronic supplementary material

The online version of this article (doi:10.1186/s12903-016-0204-1) contains supplementary material, which is available to authorized users.

Interspecific Y chromosome variation is sufficient to rescue hybrid male sterility and is influenced by the grandparental origin of the chromosomes

Y chromosomes display population variation within and between species. Co-evolution within populations is expected to produce adaptive interactions between Y chromosomes and the rest of the genome. One consequence is that Y chromosomes from disparate populations could disrupt harmonious interactions between co-evolved genetic elements and result in reduced male fertility, sterility or inviability. Here we address the contribution of 'heterospecific Y chromosomes' to fertility in hybrid males carrying a homozygous region of Drosophila mauritiana introgressed in the Drosophila simulans background. In order to detect Y chromosome-autosome interactions, which may go unnoticed in a single-species background of autosomes, we constructed hybrid genotypes involving three sister species: Drosophila simulans, D. mauritiana, and D. sechellia. These engineered strains varied due to: (i) species origin of the Y chromosome (D. simulans or D. sechellia); (ii) location of the introgressed D. mauritiana segment on the D. simulans third chromosome, and (iii) grandparental genomic background (three genotypes of D. simulans). We find complex interactions between the species origin of the Y chromosome, the identity of the D. mauritiana segment and the grandparental genetic background donating the chromosomes. Unexpectedly, the interaction of the Y chromosome and one segment of D. mauritiana drastically reduced fertility in the presence of Ysim, whereas the fertility is partially rescued by the Y chromosome of D. sechellia when it descends from a specific grandparental genotype. The restoration of fertility occurs in spite of an autosomal and X-linked genome that is mostly of D. simulans origin. These results illustrate the multifactorial basis of genetic interactions involving the Y chromosome. Our study supports the hypothesis that the Y chromosome can contribute significantly to the evolution of reproductive isolation and highlights the conditional manifestation of infertility in specific genotypic combinations.

Spectral control of high-harmonic generation via drive laser pulse shaping in a wide-diameter capillary

We experimentally investigate spectral control of high-harmonic generation in a wide-diameter (508 μm) capillary that allows using significantly lower gas pressures coupled with elevated drive laser energies to achieve higher harmonic energies. Using phase shaping to change the linear chirp of the drive laser pulses, we observe wavelength tuning of the high-harmonic output to both larger and smaller values. Comparing tuning via the gas pressure with the amount of blue shift in the transmitted drive laser spectrum, we conclude that both adiabatic and non-adiabatic effects cause pulse-shaping induced tuning of high harmonics. We obtain a fractional wavelength tuning, Δλ/λ, in the range from -0.007 to + 0.01, which is comparable to what is achieved with standard capillaries of smaller diameter and higher pressures.

Crystal structure, luminescence properties and energy transfer of Eu3+/Dy3+ doped GdNbTiO6 broad band excited phosphors

GdNbTiO₆ has been used as a broad band excited host material absorbing UV radiation, and the excitation energy is transferred from the O²⁻ → Nb⁵⁺(Ti⁴⁺) charge transfer band to the excited states of Eu³⁺/Dy³⁺ ions, presenting different emission colors.

Single-Crystal Diamond Nanowire Tips for Ultrasensitive Force Microscopy

We report the fabrication, integration, and assessment of sharp diamond tips for ultrasensitive force microscopy experiments. Two types of tips, corresponding to the upper and lower halves of a diamond nanowire, were fabricated by top-down plasma etching from a single-crystalline substrate. The lower, surface-attached halves can be directly integrated into lithographically defined nanostructures, like cantilevers. The upper, detachable halves result in diamond nanowires with a tunable diameter (50-500 nm) and lengths of a few microns. Tip radii were around 10 nm and tip apex angles around 15°. We demonstrate the integration of diamond nanowires for use as scanning tips onto ultrasensitive pendulum-style silicon cantilevers. We find the noncontact friction and frequency jitter to be exceptionally low, with no degradation in the intrinsic mechanical quality factor (Q ≈ 130,000) down to tip-to-surface distances of about 10 nm. Our results are an encouraging step toward further improvement of the sensitivity and resolution of force-detected magnetic resonance imaging.