The PARTNER trial of neoadjuvant olaparib with chemotherapy in triple-negative breast cancer.

PARTNER is a prospective, phase II-III, randomized controlled clinical trial that recruited patients with triple-negative breast cancer1,2, who were germline BRCA1 and BRCA2 wild type3. Here we report the results of the trial. Patients (n = 559) were randomized on a 1:1 basis to receive neoadjuvant carboplatin-paclitaxel with or without 150 mg olaparib twice daily, on days 3 to 14, of each of four cycles (gap schedule olaparib, research arm) followed by three cycles of anthracycline-based chemotherapy before surgery. The primary end point was pathologic complete response (pCR)4, and secondary end points included event-free survival (EFS) and overall survival (OS)5. pCR was achieved in 51% of patients in the research arm and 52% in the control arm (P = 0.753). Estimated EFS at 36 months in the research and control arms was 80% and 79% (log-rank P > 0.9), respectively; OS was 90% and 87.2% (log-rank P = 0.8), respectively. In patients with pCR, estimated EFS at 36 months was 90%, and in those with non-pCR it was 70% (log-rank P < 0.001), and OS was 96% and 83% (log-rank P < 0.001), respectively. Neoadjuvant olaparib did not improve pCR rates, EFS or OS when added to carboplatin-paclitaxel and anthracycline-based chemotherapy in patients with triple-negative breast cancer who were germline BRCA1 and BRCA2 wild type. ClinicalTrials.gov ID: NCT03150576 .

Effects of non-pairwise repulsion on nanoparticle assembly.

Electrostatic interactions provide a convenient way to modulate interactions between nanoparticles, colloids, and biomolecules because they can be adjusted by the solution pH or salt concentration. While the presence of salt provides an easy method to control the net interparticle interaction, the nonlinearities arising from electrostatic screening make it difficult to quantify the strength of the interaction. In particular, when charged particles assemble into clusters or aggregates, nonlinear effects render the interactions strongly non-pairwise. Here, we report Brownian dynamics simulations to investigate the effect that the non-pairwise nature of electrostatic interactions has on nanoparticle assembly. We compare these simulations to a system in which the electrostatics are modeled by a strictly pairwise Yukawa potential. We find that both systems show a narrow range in parameter space where the particles form well-ordered crystals. Bordering this range are regions where the net interactions are too weak to stabilize aggregated structures or strong enough that the system becomes kinetically trapped in a gel. The non-pairwise potential differs from the pairwise system in the appearance of an amorphous state for strongly charged particles. This state appears because the many-body electrostatic interactions limit the maximum density achievable in an assembly.

TORC1-signalling is down-regulated in Saccharomyces cerevisiae hsp30Δ cells by SNF1-dependent mechanisms.

Hsp30 is a plasma membrane localized heat shock protein in Saccharomyces cerevisiae whose expression is induced by numerous environmental stressors. Elucidation of its mechanism of action has remained elusive primarily because hsp30Δ cells do not show a strong phenotype. To identify cellular functions associated with Hsp30, we thus compared the transcriptome of BY4741hsp30Δ with that of its wild type counterpart. Our studies indicate down-regulation of the target of rapamycin complex 1 (TORC1)-dependent gene-expression programme in hsp30Δ cells. We further show that TORC1-signalling through its effectors (Sch9 and Tap42) was down-regulated in the deletion strain. Specifically, (a) phosphorylation levels of Sch9 were lower and nuclear exclusion of Rim15 (Sch9-downstream function) was overridden in hsp30Δ cells, (b) membrane association of Tor1 and Tap42 was lower in hsp30Δ cells, and (c) Tap42-downstream functions were abrogated in the deletion strain. Furthermore, transcription factors Rtg1, Rtg3, Gat1, and Gln3 were localized in the nucleus of the hsp30Δ as observed upon inactivation of TORC1. Studies aimed at determining how TORC1-signalling is down-regulated in hsp30Δ cells indicated that total reducing sugar levels were lower and ADP:ATP ratio was higher in hsp30Δ cells -conditions known to activate the Snf1 kinase and consequently to the inactivation of TORC1. We thus determined if TORC1-signalling could be restored in hsp30Δ cells upon the deletion of SNF1. Sch9 phosphorylation levels (TORC1-signalling) was restored to wild type levels in hsp30Δsnf1Δ cells. TORC1-signalling is thus down-regulated in hsp30Δ cells by SNF1-dependent mechanisms. A probable role for Hsp30 is discussed.

Heat stress modulated gastrointestinal barrier dysfunction: role of tight junctions and heat shock proteins.

Increased environmental temperature exerts a visible impact on an individual's physiology. At the onset of heat stress, there is an increase in core body temperature which triggers peripheral vasodilation and sweating in an effort to dissipate the elevated body heat. The increase in peripheral circulation however reduces blood flow to the internal organs which are thus adversely affected. In particular, the gastrointestinal (GI) tract gets adversely affected during hyperthermia resulting in loosening of the tight junctions (TJs) that finally leads to higher intestinal permeability. At the cellular level, elevated levels of heat shock proteins (HSPs) induced in response to heat stress mediated cytoprotection by maintaining proper protein folding, releasing survival signals and preserving cytoskeleton integrity. Recent studies have indicated that HSPs play a crucial role in maintaining the localization of TJ proteins. Dietary supplements have also shown to have a positive effect on the maintenance of intestinal TJs. Therefore, it becomes imperative to understand the cellular, molecular and physiological alterations in response to heat stress in GI tract. In the present report, the effect of thermal stress on GI tract has been summarized. Specific role of HSPs along with mitogen activated protein (MAP) kinase signaling pathway in response to hyperthermia has also been discussed.

The partial light scattering cross section of spherical particles.

We define the partial scattering cross section and partial efficiencies to demonstrate that the total scattering is the sum of two roughly equal parts: approximately half from the forward scattering lobe due to 2D diffraction by the projected sphere and half from the 2D to 3D diffraction crossover. The first part is at angles such that θ≲λ/D, a result previously known, which can be quite small for large particles. The second part is in a new regime we call the "hump," visible in q-space, which to a good approximation contains the other half of the scattered light. The hump disappears when the imaginary part of the refractive index is significant.

Backscattering measurements of micron-sized spherical particles.

An apparatus was designed and assembled to measure scattered light in the range of 180°±6° where enhanced backscattering, the cause of a glory, occurs. The apparatus was calibrated and tested using Fraunhofer circular aperture diffraction, angle of incidence correction, and a diffuse reflector. Theory indicates that backscattering is strongly dependent on particle size, refractive index, and shape. Experimental measurements from polystyrene latex spheres of two sizes and water droplets showed good agreement with Mie theory, but also indicated the extreme sensitivity of the backscattering to particle parameters. The results presented should have use in the fields of particle scattering, particle metrology, and LIDAR.

Effect of the imaginary part of the refractive index on light scattering by spheres.

For spheres of arbitrary radius R and complex index of refraction n+iκ, we identify a new parameter that indicates when the imaginary part κ seriously affects the scattering by a sphere. The parameter is κkR, where k is the wave vector magnitude, such that when κkR grows larger than one, the scattering is affected and, when κkR>3, the effects saturate. The effects are uncovered and demonstrated with Q-space analysis. The physical basis for κkR lies in the fact that it is the ratio of the radius to the optical skin depth.

Crossover from spherical particle Mie scattering to circular aperture diffraction.

This paper demonstrates the manner in which the Mie results for light scattering by a three-dimensional sphere of arbitrary size and refractive index crosses over to Fraunhofer diffraction by a two-dimensional circular aperture of the same radius in the limit of very large radius. Demonstration is feasible only because the graphical results are plotted in the manner of the Q-space analysis that plots scattered intensity versus the logarithm of the magnitude of the scattering wave vector rather than linear versus the scattering angle.

ATP depletion triggers acute myeloid leukemia differentiation through an ATR/Chk1 protein-dependent and p53 protein-independent pathway.

Despite advances in oncology drug development, most commonly used cancer therapeutics exhibit serious adverse effects. Often the toxicities of chemotherapeutics are due to the induction of significant DNA damage that is necessary for their ability to kill cancer cells. In some clinical situations, the direct induction of significant cytotoxicity is not a requirement to meet clinical goals. For example, differentiation, growth arrest, and/or senescence is a valuable outcome in some cases. In fact, in the case of acute myeloid leukemia (AML), the use of the differentiation agent all-trans-retinoic acid (ATRA) has revolutionized the therapy for a subset of leukemia patients and led to a dramatic survival improvement. Remarkably, this therapeutic approach is possible even in many elderly patients, who would not be able to tolerate therapy with traditional cytotoxic chemotherapy. Because of the success of ATRA, there is widespread interest in identifying differentiation strategies that may be effective for the 90-95% of AML patients who do not clinically respond to ATRA. Utilizing an AML differentiation agent that is in development, we found that AML differentiation can be induced through ATP depletion and the subsequent activation of DNA damage signaling through an ATR/Chk1-dependent and p53-independent pathway. This study not only reveals mechanisms of AML differentiation but also suggests that further investigation is warranted to investigate the potential clinical use of low dose chemotherapeutics to induce differentiation instead of cytotoxicity. This therapeutic approach may be of particular benefit to patients, such as elderly AML patients, who often cannot tolerate traditional AML chemotherapy.

Self-assembly of a bipolar model of biomacromolecules.

Extending recent work on a generic bipolar model proposed to study the nanochain formation of amelogenin molecules, we conduct a systematic investigation in this paper on the self-assembly of such a model via sweeping the relative parameter space. The bipolar model consists of a short-range attraction and an off-center Coulomb repulsion for the supermolecule. Through the Brownian dynamics simulation of both translational and rotational motions, we study the kinetics of the self-assembly and the structure of clusters formed within the system for various interaction settings. From the results of structure factor and cluster analysis, we find that the range of the repulsive interaction has a sensitive impact in controlling the cluster size, while the strength of the attractive interaction dominates the cluster morphology such that the greater the attraction among particles, the more elongated the cluster formed.

Ganglioneuroma presenting as subpulmonic effusion-a differential to consider?

Ganglioneuroma is a benign, slow-growing neurogenic tumor arising from neural crest cells. It is extremely rare (1/1,000,000) and is located most commonly in the posterior mediastinum (41.5%), retroperitoneum (37.5%), and adrenal glands (21%). We present a case of a 62-year-old lady who had complaints of shortness of breath on exertion and dyspnea for the past 3 months. She had no other significant history. Computerised tomography (CT) scan of the thorax suggested left-sided loculated subpulmonic pleural effusion, 14 × 12 cm in dimension. She underwent assisted video-assisted thoracoscopic surgery (VATS) exploration of the thorax with debridement and drainage of subpulmonic collection that was abutting the diaphragm, along with release of trapped lung. Histopathological examination showed multiple ruptured cystic masses with nodules; microscopical evidences of Schwann cells, ganglion cells, and spindle cells-all these along with immunohistochemistry-revealed features consistent with ganglioneuroma. Postoperative recovery was uneventful, and the patient did not have any complaints or other limitations to daily life activities at 6 months' follow-up. Ganglioneuroma is essentially benign in nature, asymptomatic, and rare. A systematic review of the literature has shown that giant-sized ganglioneuromas (size more than 10 cm) have rarely been reported. Surgical excision and clearance is the treatment modality of choice. In our case, due to large size and difficulty in access and mobilisation of the mass adherent to the diaphragm, assisted VATS had to be performed. We increased the size of the utility port from 5 to 10 cm and used a rib retractor for better surgical negotiation. This could have been more challenging, as there have been incidences where ganglioneuromas have extended both into the thoracic and abdominal cavities and even involved vital organs and vessels. Regular follow-up is essential, as late recurrence and slow progression potential is a known complication.

Shear history independence in colloidal aggregation.

Stimulated by experiments, we have carried out detailed simulations of aggregation in the presence of shear in a model colloidal system with a short-range attractive potential. For weak shear rates, we find that the shear enhanced the aggregation and that the long-time state of the system is independent of the shear history. For strong shear rates, precipitous fragmentation occurred after the shear was turned on and, after an induction period, the aggregation quickly rebounded in a stochastic manner similar to classical nucleation phenomena. However, the long-time state of the system is, once again, independent of the shear history. Thus, for both weak and strong shear cases, the shear rate acts as a state variable of the aggregating system. Shear rates employed in the simulations can be attained in laboratory experiments, as confirmed by computing the dimensionless Péclet numbers.

Homologous Recombination is Activated at Early Time Points Following Exposure to Cobalt Chloride Induced Hypoxic Conditions in Saccharomyces cerevisiae.

DNA repair functions are essential for the maintenance of genetic integrity and are regulated in response to both environmental and chemical stressors in mammalian and yeast cells in culture. The inhibitory effect of limited O2 availability on DNA repair functions in general and on homologous recombination (HR) in particular, correlates with increased chromosomal abnormalities in hypoxic cancer cells. Given the above, we have investigated the effects of CoCl2,--a hypoxia mimetic agent on HR and genetic aberrations in Saccharomyces cerevisiae. Our studies demonstrate that both acute and chronic exposure to CoCl2 activated HR and increased genetic aberrations in S. cerevisiae D7 cells. At early time points following addition of CoCl2 to the growth media, cells were briefly arrested in the G1-S boundary concomitant with a transient increase in Rad52-GFP foci formation and induction of low levels of DNA damage. The mode of action of CoCl2 is thus similar to that of DNA synthesis inhibitors, the later are known to induce HR and cause G1-S arrest. We propose that the activation of HR in the presence of the hypoxia mimetic agent may be attributed to the replication stress and/or DNA damage induced by the stressor.

Tolerance to thermal and reductive stress in Saccharomyces cerevisiae is amenable to regulation by phosphorylation-dephosphorylation of ubiquitin conjugating enzyme 1 (Ubc1) S97 and S115.

Ubiquitin conjugating enzyme 1 (Ubc1) is a member of the E2 family of enzymes that conjugates ubiquitin to damaged proteins destined for degradation by the ubiquitin proteasomal system. It is necessary for stress tolerance and is essential for cell survival in Saccharomyces cerevisiae. Ubc1 has five serine residues that are potential substrates for phosphorylation by kinases. However, no data are available to indicate that Ubc1 function or stress tolerance in S. cerevisiae is regulated by serine phosphorylation of Ubc1. We demonstrate that Ubc1 is phosphorylated in serine residue(s). Furthermore, expression of Ubc1 mutants that are 'constitutively phosphorylated' or 'dephosphorylated' in mitogen-activated protein (MAP) kinase serine residues (S97 and S115) affected tolerance to thermal and reductive stress in S. cerevisiae. Specifically, expression of Ubc1S97A and S115D increased thermo-tolerance in both BY4741 and TetO7 -UBC1ura3Δ cells. Serine phosphorylation of Ubc1 was decreased in BY4741 cells following exposure at 40 °C. Tolerance to reductive stress in the same strains correlated with the expression of Ubc1S97A. Ubc1 phosphorylation did not show significant alteration under similar conditions. Both hog1Δ and slt2Δ cells expressing Ubc1S115D and Ubc1S115A were rendered tolerant to thermal and reductive stress respectively. Ubc1 phosphorylation was higher in BY4741 cells compared to hog1Δ cells at 30 °C and was significantly reduced in BY4741 cells upon exposure at 40 °C. Taken together, the cell survival assays and Ubc1 phosphorylation status in strains and under conditions as described above suggest that tolerance to thermal and reductive stress in S. cerevisiae may be regulated by MAP kinase-mediated phosphorylation of Ubc1S97 and S115.

Securinine induces p73-dependent apoptosis preferentially in p53-deficient colon cancer cells.

The identification of agents that preferentially kill cancer cells while protecting normal cells offers the potential to overcome toxicities found in many existing chemotherapeutic agents. Because p53 is frequently inactivated in cancer, agents that preferentially kill p53-null cells and protect wild-type p53-expressing cells are highly desirable chemotherapeutic agents. By using pairs of isogenic colon cancer cell lines that differ only in p53 expression (RKO and HCT116), securinine was found to exhibit these properties. Securinine (30 microM) induces apoptosis in 73% of p53-null HCT116 cells (LD(50) 17.5 microM) as opposed to 17.6% of HCT116 parental cells (LD(50) 50 microM) at 72 h after treatment. The mechanism of securinine-mediated death in p53-deficient cells involves the induction of the p53 family member, p73. Interestingly, the proapoptotic protein p73 is down-regulated in colon cancer cells expressing p53. This differential regulation of p73 in a p53-dependent fashion reveals a novel pathway for preferentially targeting cancer cells. In contrast to p53-deficient cells, cells expressing p53 are protected from cell death through the p53-mediated up-regulation of p21. These studies reveal a novel approach to specifically target colon cancer cells lacking p53 as well as identify a novel clinically relevant pathway to selectively induce p73 in p53-null cells.

Saccharomyces cerevisiae Hsp30 is necessary for homeostasis of a set of thermal stress response functions.

Saccharomyces cerevisiae Hsp30 is a plasma membrane heat shock protein which is induced by various environmental stress conditions. However functional role of Hsp30 during diverse environmental stressors is not presently known. To gain insight into its function during thermal stress, we have constructed and characterized a hsp30 strain during heat stress. BY4741Deltahsp30 cells were found to be more sensitive compared to BY4741 cells when exposed to a lethal heat stress at 50 degrees Celsius. When budding yeast is exposed to either heat shock or weak organic acid, it inhibits Pma1p activity. In this study we measured the levels of Pma1p in mutant and Wt cells both during optimal temperature and heat shock temperature. We observed that BY4741Deltahsp30 cells showed constitutive reduction of Pma1p. To gain further insights into the role of Hsp30 during heat stress, we compared total protein profile by 2D gel electrophoresis followed by identification of differentially expressed spots by LC-MS. We observed that contrary to that expected from thermal stress induced changes in gene expression, the Deltahsp30mutant maintained elevated levels of Pdc1p, Trx1p and Nbp35p and reduced levels of Atp2p and Sod1p during heat shock. In conclusion, Hsp30 is necessary during lethal heat stress, for the maintenance of Pma1p and a set of thermal stress response functions.

Understanding the practice of thoracic surgery during the COVID-19 pandemic.

The COVID-19 pandemic has affected the entire medical community including the thoracic surgical practice. The guidelines, consensus statements, and preliminary recommendations published by the thoracic surgeons so far have appreciated the importance of triage of patients with thoracic surgical diseases and multidisciplinary team (MDT) meeting. Delaying surgery or planning alternative treatment in patient care should be done by taking input from experts in thoracic specialties. The procedures that can be carried out in a hospital are based on the prevalence of COVID-19 patients within the hospital and availability of hospital resources. As a result, proper triaging, ensuring safety of patient and health care personnel, and optimal utilization of the available resources remain the cornerstone while fighting the COVID-19 pandemic. In this manuscript, we highlight these issues with respect to practice of thoracic surgery.

p38 MAPK pathway-dependent SUMOylation of Elk-1 and phosphorylation of PIAS2 correlate with the downregulation of Elk-1 activity in heat-stressed HeLa cells.

Stress-activated and mitogen-activated protein kinases (MAPKs) regulate gene expression by post-translational modifications of transcription factors. Elk-1, a transcription factor that regulates the expression of immediate early genes, is amenable to regulation by all the three mammalian MAPKs. In the present report, using inhibitors specific for different MAPK pathways, we show that during exposure of HeLa cells to heat stress, Elk-1 is SUMOylated with SUMO1 by p38 MAPK pathway-dependent mechanisms. Elk-1-phosphorylation levels were significantly reduced under similar conditions. We also show that transcriptional activity of Elk-1 as assessed by luciferase reporter expression and qPCR estimation of the expression of genes regulated by Elk-1 was downregulated upon exposure to heat stress; this downregulation was reversed when heat exposure was performed in the presence of either SB203580 (p38 MAPK inhibitor) or ginkgolic acid (inhibitor of SUMOylation). Elk-1 induced transcription is also regulated by PIAS2 which acts as a coactivator upon the activation of extracellular signal-regulated kinases (ERKs) and as a corepressor upon its phosphorylation by p38 MAPK. Since heat stress activates the p38 MAPK pathway, we determined if PIAS2 was phosphorylated in heat-stressed HeLa cells. Our studies indicate that in HeLa cells exposed to heat stress, PIAS2 is phosphorylated by p38 MAPK pathway-dependent mechanisms. Collectively, the results presented demonstrate that in heat-stressed HeLa cells, p38 MAPK pathway-dependent SUMOylation of Elk-1 and phosphorylation of PIAS2 correlate with the downregulation of transactivation by Elk-1.

Malignant perivascular epitheloid cell tumour (PEComa) of the lung - a rare entity.

Malignant Perivascular Epitheloid Cell Tumour (PEComa) of the lung is very rare, with only six cases reported in literature. This case presented with a large mass originating from right upper lobe of the lung with dilemma in its histopathological diagnosis and management. Postoperative histopathology after a right upper and middle lobectomy describes a tumour with an alveolar/nested pattern of growth and epitheloid morphology with expression of TFE-3 and diagnosed as PEComa. After 6 months the patient had a local recurrence inside the thorax & chest wall.This case qualifies it as a rare type of malignant PEComa with younger age of presentation, aggressive clinical behaviour & malignant histological features along with TFE3 positivity on immunohistochemistry. This case is probably the first of its kind with the largest reported size involving two lobes of the lung.

Detection of an mRNA polymorphism by differential display.

Differential display technology was utilized to compare programs of gene expression in primary cultures of human skin fibroblasts from normal volunteers and patients diagnosed with melancholic depression. Polymorphic transcripts of a single gene differing by one tandem repeat sequence of four nucleotides (TGAT) in the 3' noncoding region were detected.