Vortex formation with a snapping shrimp claw

Snapping shrimp use one oversized claw to generate a cavitating high speed water jet for hunting, defence and communication. This work is an experimental investigation about the jet generation. Snapping shrimp (Alpheus-bellulus) were investigated by using an enlarged transparent model reproducing the closure of the snapper claw. Flow inside the model was studied using both High-Speed Particle Image Velocimetry (HS-PIV) and flow visualization. During claw closure a channel-like cavity was formed between the plunger and the socket featuring a nozzle-type contour at the orifice. Closing the mechanism led to the formation of a leading vortex ring with a dimensionless formation number of approximate ΔT*≈4. This indicates that the claw might work at maximum efficiency, i.e. maximum vortex strength was achieved by a minimum of fluid volume ejected. The subsequent vortex cavitation with the formation of an axial reentrant jet is a reasonable explanation for the large penetration depth of the water jet. That snapping shrimp can reach with their claw-induced flow. Within such a cavitation process, an axial reentrant jet is generated in the hollow cylindrical core of the cavitated vortex that pushes the front further downstream and whose length can exceed the initial jet penetration depth by several times.

Characteristics of males infected with common Neisseria gonorrhoeae sequence types in the Gonococcal Isolate Surveillance Project, San Francisco, California, 2009

We analyzed 265 urethral Neisseria gonorrhoeae specimens collected from symptomatic males at San Francisco's municipal sexually transmitted disease clinic, a participant in the Gonococcal Isolate Surveillance Project, during 2009. We used N. gonorrhoeae multiantigen sequence typing to describe characteristics of patients infected with common sequence type families. Specimens were classified into 6 homology-based families and 1 additional family of all other identified strains. Strain family results were combined with results of culture-based antibiotic sensitivity minimum inhibitory concentration, sociodemographic and behavioral risk data collected at the clinic, and presence or absence of the mosaic penicillin-binding protein 2 (penA) allele. Characteristics of patients were compared across strain families through the use of χ(2) statistics. Among men who have sex with men, strain distribution differed by those reporting receptive oral sex as their only urethral exposure (P = 0.04), by number of sex partners (P = 0.03), and by race/ethnicity (P < 0.001); there were no differences by age or human immunodeficiency virus status. Also, among men who have sex with men, strain family distributions differed for culture specimens with reduced susceptibility to a range of antibiotics, as well as with presence of the mosaic penA allele (all P < 0.001). The combination of molecular, phenotypic, and epidemiologic data on N. gonorrhoeae infection could help develop a more complete epidemiology of gonorrhea in the United States.

Heterozygosity for an inactivating mutation in low-density lipoprotein-related receptor 6 (Lrp6) increases osteoarthritis severity in mice after ligament and meniscus injury

OBJECTIVE

Wnt/β-catenin signaling plays an integral and complex role in cartilage development and maintenance. β-catenin signaling has been linked to osteoarthritis (OA), but the role of Lrp6-mediated Wnt/β-catenin signaling during OA remains unexplored. Mutations in the Wnt/β-catenin co-receptors LRP5 and LRP6 (low-density lipoprotein-related receptors 5 and 6) result in skeletal abnormalities, which tend to be more severe in Lrp6 mutant mice. We examined OA development, chondrocyte and osteoblast behavior, and β-catenin signaling after ligament and meniscus damage in mice with global heterozygous deletion of Lrp6.

DESIGN

Ligament and meniscus damage was surgically induced in Lrp6(+/-) and wild-type (WT) mice, and evidence of joint disease was assessed by Microcomputed tomography (micro-CT) and histology. Wnt/β-catenin signaling, proliferation, apoptosis, chondrogenesis, osteogenesis, and catabolic enzyme activity were measured.

RESULTS

Relative to WT mice, Lrp6(+/-) mice had lower nuclear β-catenin signaling within articular cartilage. After surgery, osteophytes and reduced articular cartilage were apparent in WT mice, but more severe in Lrp6(+/-) animals. Impairments to trabecular bone geometry occurred for WT and Lrp6(+/-) mice after surgery. Relative to WT mice, Lrp6(+/-) mice had reduced trabecular BMD and thickness, and Cyclin D1 and Lrp6 gene expression after surgery. There was an increase in apoptotic cells and serum matrix metalloproteinase-9 (MMP9) for Lrp6(+/-) mice after surgery, but no differences in cell proliferation occurred.

CONCLUSIONS

Heterozygous loss-of-function mutation in Lrp6 leads to less β-catenin signaling within articular cartilage and to increased degenerative joint disease after ligament and meniscus injury. Modulation of Lrp6 function could attenuate joint disease after damage to ligaments and the meniscus.

Abstract 3324: Cyclooxygenase-2 mediated breast cancer progression by induction of stem like cells and micro RNA

We established that elevated COX-2 expression by human and murine breast cancer cells promotes tumor progression and metastasis via multiple mechanisms primarily due to activation of the PGE-2 receptor EP4. COX-2 and HER-2, often co-expressed in human breast cancer, are both major determinants of cancer progression. Many of the HER-2 actions were shown to be COX-2 dependent, but the roles of COX-2 in the absence or presence of HER-2 in breast cancer initiation and sustenance remain unclear. To define these roles, we examined the consequences of introducing COX-2 gene into COX-2-ve, HER-2-ve, ER+ve, non-metastatic MCF-7 and COX-2-ve, ER-ve, HER-2-over-expressing SK-BR-3 human breast cancer cell lines. After stable integration of COX-2 cDNA, these two cell lines were named MCF-7-COX-2 and SKBR3-COX-2. When compared with their empty vector-transfected counterparts, they showed (1) epithelial-mesenchymal transition (down regulation of E Cadherin and up regulation Vimentin by qRT-PCR), (2) higher proliferative activity (BrdU uptake), (3) higher migratory and invasive abilities across microporous membranes (8μM pore size) in Boyden chambers, (4) upregulation of EP4 and angiogenic and lymphangiogenic factors VEGF-A, C and D (qRT PCR and western blot), (5) markedly increased stem like cell populations in vitro (spheroid forming ability of single cells in ultra-low attachment plates for successive generations) and an increase in ALDH activity (flow cytometry). (6) Above changes could be abrogated with specific COX-2 inhibitor NS-398 (Pfizer) or an EP4 antagonist ONO-AE3-208 (ONO Pharmaceuticals, Japan) at non toxic concentrations, indicating that all these functions are dependent on COX-2 and EP4 activity. (7) Intravenous injection of MCF-7-COX2 cells into immuno-deficient mice revealed a dramatic increase in their lung colony forming capacity at 4-6 weeks, as compared to empty vector-transfected cells. (8) Using differential gene and micro-RNA (miRNA) arrays we identified two miRNAs upregulated and their target fourteen tumor-suppressor like genes down-regulated by introducing COX-2 into MCF-7 cells. (9) We observed a positive co-relation between the miRNA and COX-2 expression in multiple COX-2 disparate cell lines, in which expression of miRNAs was inhibited by treatment with COX-2 inhibitors or EP4 antagonists. Current studies are testing the functions of the miRNAs by knockdown and knock-in studies, and utilizing human breast cancer tissues to explore the clinical relevance of these findings. Our model system allowing identification and characterization of COX-2 induced stem like cells in breast cancer should help defining COX-2 and EP4 mediated pathways controlling their biology and utilization of the novel miRNA markers for prognostic and therapeutic applications in the clinic. (Supported by the CBCF, Ontario Chapter and the OICR funds from the Government of Ontario to PKL).

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3324. doi:1538-7445.AM2012-3324

2-De-oxy-α-d-arabino-hexopyran-ose

The title compound, C₆H₁₂O₅, is the α-pyran­ose form of the reducing aldose 2-de­oxy-d-arabino-hexose. The six-membered pyran­ose ring adopts a ⁴C₁ conformation, with the anomeric hy­droxy group in axial and the other substituents in equatorial positions. In the crystal, each of the four hy­droxy groups acts as an inter­molecular hydrogen-bond donor function, resulting in a three-dimensional hydrogen-bonded network.

Phenylboronic acid esters of the common 2-deoxy-aldoses

Phenylboronic acid esters are formed by the three common 2-deoxy aldoses: 2-deoxy-d-erythro-pentose ('2-deoxy-d-ribose'), 2-deoxy-d-lyxo-hexose ('2-deoxy-d-galactose'), and 2-deoxy-d-arabino-hexose ('2-deoxy-d-glucose'). The major species that was formed from equimolar quantities of boronic acid and the aldose, was the 3,4-monoester of the pentopyranose in a skew-boat conformation, and the 4,6-monoester in the case of the two hexopyranoses. A double molar quantity of boronic acid led, for both 2-deoxy-hexoses, to the diester of the open-chain aldehydo isomer as the major product: the 3,5:4,6-diester for the lyxo-configured deoxy-hexose, and the 3,4:5,6-diester of the arabino-configured isomer. Minor products of all reactions were identified by a combined NMR/DFT methodology.

Multiscale Simulations of Brittle Fracture and the Quantum-Mechanical Nature of Bonding in Silicon

We simulate the microscopic details of brittle fracture in silicon by dynamically coupling empirical-potential molecular dynamics of a strained sample to a quantum-mechanical description of interatomic bonding at the crack tip. Our simulations show brittle fracture at loads comparable to experiment, in contrast with empirical potential simulations that show only ductile crack propagation at much higher loading. While the ductility of the empirical potentials can be attributed to their short range, it is unclear whether the increased range of the tight-binding description is sufficient to explain its brittle behavior. Using the multiscale method we show that at a temperature of 1100 K, but not at 900 K, a dislocation is sometimes nucleated when the crack tip impinges on a vacancy. While this result is too limited in length and time scales to directly correspond to experimental observations, it is suggestive of the experimentally observed brittle to ductile transition.

Quantitative analysis of fitness and genetic interactions in yeast on a genome scale

Global quantitative analysis of genetic interactions is a powerful approach for deciphering the roles of genes and mapping functional relationships among pathways. Using colony size as a proxy for fitness, we developed a method for measuring fitness-based genetic interactions from high-density arrays of yeast double mutants generated by synthetic genetic array (SGA) analysis. We identified several experimental sources of systematic variation and developed normalization strategies to obtain accurate single- and double-mutant fitness measurements, which rival the accuracy of other high-resolution studies. We applied the SGA score to examine the relationship between physical and genetic interaction networks, and we found that positive genetic interactions connect across functionally distinct protein complexes revealing a network of genetic suppression among loss-of-function alleles.

Estradiol suppresses tissue androgens and prostate cancer growth in castration resistant prostate cancer

Background

Estrogens suppress tumor growth in prostate cancer which progresses despite anorchid serum androgen levels, termed castration resistant prostate cancers (CRPC), although the mechanisms are unclear. We hypothesize that estrogen inhibits CRPC in anorchid animals by suppressing tumoral androgens, an effect independent of the estrogen receptor.

Methods

The human CRPC xenograft LuCaP 35V was implanted into orchiectomized male SCID mice and established tumors were treated with placebo, 17β-estradiol or 17β-estradiol and estrogen receptor antagonist ICI 182,780. Effects of 17β-estradiol on tumor growth were evaluated and tissue testosterone (T) and dihydrotestosterone (DHT) evaluated by mass spectrometry.

Results

Treatment of LuCaP 35V with 17β-estradiol slowed tumor growth compared to controls (tumor volume at day 21: 785 ± 81 mm³ vs. 1195 ± 84 mm³, p = 0.002). Survival was also significantly improved in animals treated with 17β-estradiol (p = 0.03). The addition of the estrogen receptor antagonist ICI 182,780 did not significantly change survival or growth. 17β-estradiol in the presence and absence of ICI 182,780 suppressed tumor testosterone (T) and dihydrotestosterone (DHT) as assayed by mass spectrometry. Tissue androgens in placebo treated LuCaP 35V xenografts were; T = 0.71 ± 0.28 pg/mg and DHT = 1.73 ± 0.36 pg/mg. In 17β-estradiol treated LuCaP35V xenografts the tissue androgens were, T = 0.20 ± 0.10 pg/mg and DHT = 0.15 ± 0.15 pg/mg, (p < 0.001 vs. controls). Levels of T and DHT in control liver tissue were < 0.2 pg/mg.

Conclusions

CRPC in anorchid animals maintains tumoral androgen levels despite castration. 17β-estradiol significantly suppressed tumor T and DHT and inhibits growth of CRPC in an estrogen receptor independent manner. The ability to manipulate tumoral androgens will be critical in the development and testing of agents targeting CRPC through tissue steroidogenesis.

Low-Dose Fulvestrant Maintained Long-Term Complete Remission after Poor Response to Previous Endocrine Therapies in a Patient with Advanced Breast Cancer

We report a case of long-term (9 years) response to 4th-line endocrine treatment with fulvestrant given for advanced breast cancer after no or poor response to prior endocrine therapies. Complete remission was achieved with full dose and maintained even after dose reduction due to unanticipated intensity of mucosal toxicity. Complete remission was temporarily lost after fulvestrant was tentatively withdrawn (63 months after treatment start), but was re-achieved after renewal of half-dose treatment and last reconfirmed 90 months after treatment start. The pharmacokinetic profile provides evidence to hypothesize a unique sensitivity to fulvestrant in this patient which might explain both: toxicity and extraordinary efficacy.

PKB/AKT phosphorylation of the transcription factor Twist-1 at Ser42 inhibits p53 activity in response to DNA damage

Protein kinase B (PKB/Akt) is ubiquitously expressed in cells. Phosphorylation of its multiple targets in response to various stimuli, including growth factors or cytokines, promotes cell survival and inhibits apoptosis. PKB is upregulated in many different cancers and a significant amount of the enzyme is present in its activated form. Here we show that PKB phosphorylates one of the anti-apoptotic proteins--transcription factor Twist-1 at Ser42. Cells expressing Twist-1 displayed inefficient p53 upregulation in response to DNA damage induced by gamma-irradiation or the genotoxic drug adriamycin. This influenced the activation of p53 target genes such as p21(Waf1) and Bax and led to aberrant cell-cycle regulation and the inhibition of apoptosis. The impaired induction of these p53 effector molecules is likely to be mediated by PKB-dependent phosphorylation of Twist-1 because, unlike the wild-type mutant, the Twist-1 S42A mutant did not confer cell resistance to DNA damage. Moreover, phosphorylation of Twist-1 at Ser42 was shown in vivo in various human cancer tissues, suggesting that this post-translational modification ensures functional activation of Twist-1 after promotion of survival during carcinogenesis.

Antiangiogenic drugs in oncology: a focus on drug safety and the elderly - a mini-review

Angiogenesis is essential for normal tissue and even more so for solid malignancies. At present, inhibition of tumor angiogenesis is a major focus of anticancer drug development. Bevacizumab, a humanized antibody against VEGF, was the first antiangiogenic agent to be approved for advanced non-small cell lung cancer, breast cancer and colorectal cancer. The most commonly observed adverse events are hypertension, proteinuria, bleeding and thrombosis. Sunitinib, a small molecule blocking intracellular VEGF, KIT, Flt3 and PDGF receptors, which regulate angiogenesis and cell growth, is approved for the treatment of advanced renal cell cancer (RCC) and malignant gastrointestinal stromal tumor. The most frequent adverse events include hand-foot syndrome, stomatitis, diarrhea, fatigue, hypothyroidism and hypertension. Sorafenib, an oral multikinase inhibitor, is approved for the second-line treatment of advanced RCC and upfront treatment of advanced hepatocellular carcinoma. Most common adverse events with sorafenib are dermatologic (hand-foot skin reaction, rash, desquamation), fatigue, diarrhea, nausea, hypothyroidism and hypertension. More recently, cardiovascular toxicity has increasingly been recognized as a potential adverse event associated with sunitinib and sorafenib treatment. Elderly patients are at increased risk of thromboembolic events when receiving bevacizumab, and potentially for cardiac dysfunction when receiving sunitinib or sorafenib. The safety of antiangiogenic drugs is of special concern when taking these agents for longer-term adjuvant or maintenance treatment. Furthermore, newer investigational antiangiogenic drugs are briefly reviewed.