Inhibition of autocrine HGF maturation overcomes cetuximab resistance in colorectal cancer.

Although amplifications and mutations in receptor tyrosine kinases (RTKs) act as bona fide oncogenes, in most cancers, RTKs maintain moderate expression and remain wild-type. Consequently, cognate ligands control many facets of tumorigenesis, including resistance to anti-RTK therapies. Herein, we show that the ligands for the RTKs MET and RON, HGF and HGFL, respectively, are synthesized as inactive precursors that are activated by cellular proteases. Our newly generated HGF/HGFL protease inhibitors could overcome both de novo and acquired cetuximab resistance in colorectal cancer (CRC). Conversely, HGF overexpression was necessary and sufficient to induce cetuximab resistance and loss of polarity. Moreover, HGF-induced cetuximab resistance could be overcome by the downstream MET inhibitor, crizotinib, and upstream protease inhibitors. Additionally, HAI-1, an endogenous inhibitor of HGF proteases, (i) was downregulated in CRC, (ii) exhibited increased genomic methylation that correlated with poor prognosis, (iii) HAI-1 expression correlated with cetuximab response in a panel of cancer cell lines, and (iv) exogenous addition of recombinant HAI-1 overcame cetuximab resistance in CC-HGF cells. Thus, we describe a targetable, autocrine HAI-1/Protease/HGF/MET axis in cetuximab resistance in CRC.

Metabolic Response to Small Molecule Therapy in Colorectal Cancer Tracked with Raman Spectroscopy and Metabolomics.

Despite numerous screening tools for colorectal cancer (CRC), 25% of patients are diagnosed with advanced disease.  Novel diagnostic technologies that are early, accurate, and rapid are imperative to assess the therapeutic efficacy of clinical drugs and identify new biomarkers of treatment response. Here Raman spectroscopy (RS) was used to track metabolic reprogramming in KRAS-mutant HCT116 and SW837 cells, and KRAS wild-type CC cells. RS combined with multivariate analysis methods distinguished nonresponsive, partially responsive, and responsive cells treated with cetuximab, a monoclonal antibody for EGFR inhibition, sotorasib, a clinically approved KRAS inhibitor, and various doses of trametinib, an inhibitor of the MAPK pathway. Cells treated with a combination of subtoxic doses of trametinib and BKM120, an inhibitor of the PI3K pathway, showed a synergistic response between the two pathways. Using a supervised machine learning regression model, we established a scoring methodology trained to a priori predict therapeutic response to new treatment combinations. RS metabolites were verified with mass spectrometry, and enrichment pathways were identified, including amino acid, purine, and nicotinate and nicotinamide metabolism that differentiated monotherapy from combination therapy. Our approach may ultimately be applicable to patient-derived primary cells and cultures of patient tumors to predict effective drugs for individualized care.

A laser flash photolysis study of the free radical chemistry of lipoic acid and dihydrolipoic acid.

The free radical chemistry of lipoic acid (LA) and dihydrolipoic acid (DHLA) intersect at the point where DHLA loses hydrogen to a good hydrogen abstracting radical, while LA reacts with strongly reducing ketyl radicals capable of donating a hydrogen atom. While aliphatic thiyl radicals have an absorbance at ~ 330 nm, the resulting radical, formally also a thiyl radical has distinct spectroscopic properties with a maximum at 385 nm, suggesting that the two sulphur centres interact strongly with each other as part of the chromophore. The reactions that form these radicals were studied by laser flash photolysis that revealed DHLA as an excellent hydrogen donor, while LA is an excellent hydrogen acceptor. The results support earlier evidence that the real antioxidant is DHLA, while LA is not; yet, the reported facile interconversion of the two molecules suggests that LA may be a better supplement, given its shelf stability, compared with a far more difficult-to-handle DHLA.

Laser flash photolysis of titanium dioxide suspensions for the evaluation of solvent-mediated radical reactions.

The chemistry originating from the scavenging of the highly electrophilic hole in TiO2 can be readily monitored using laser flash photolysis techniques. Dilute suspensions are sufficiently transparent in the UV region that long lived signals from reactions of solvent radicals with 1,1-diphenylethylene can be readily monitored. Transient signals originating from hole, electron and trapped radicals are extremely long lived showing stretched exponentials (nanoseconds to milliseconds), adequately described by fractal models.

Gradual implementation of the meiotic recombination program via checkpoint pathways controlled by global DSB levels.

During meiosis, Spo11-induced double-strand breaks (DSBs) are processed into crossovers, ensuring segregation of homologous chromosomes (homologs). Meiotic DSB processing entails 5' end resection and preferred strand exchange with the homolog rather than the sister chromatid (homolog bias). In many organisms, DSBs appear gradually along the genome. Here we report unexpected effects of global DSB levels on local recombination events. Early-occurring, low-abundance "scout" DSBs lack homolog bias. Their resection and interhomolog processing are controlled by the conserved checkpoint proteins Tel1(ATM) kinase and Pch2(TRIP13) ATPase. Processing pathways controlled by Mec1(ATR) kinase take over these functions only above a distinct DSB threshold, resulting in progressive strengthening of the homolog bias. We conclude that Tel1(ATM)/Pch2 and Mec1(ATR) DNA damage response pathways are sequentially activated during wild-type meiosis because of their distinct sensitivities to global DSB levels. Moreover, relative DSB order controls the DSB repair pathway choice and, ultimately, recombination outcome.

Photosensitized selective semi-oxidation of tetrahydroisoquinoline: a singlet oxygen path.

Selective semi-oxidation of tetrahydroisoquinoline (THIQ) leads to a valuable dihydroisoquinoline (DHIQ) derivative via singlet oxygen photooxidation process. Typical photosensitisers (i.e., Ru complexes) can activate the reaction even under heterogeneous conditions that facilitate catalyst separation and reusability. In contrast to DHIQ, THIQ acts as an efficient singlet oxygen quencher driving the reaction selectivity. The reaction can also be facilitated by semiconductor catalysts such as MoCo@GW, a glass wool-based catalyst that is easy to separate and reuse and compatible with flow photochemistry. Its role is to mediate the formation of isoquinoline (IQ) and thus an in situ-generated singlet oxygen catalyst. Laser flash photolysis with NIR detection provides proof of the singlet oxygen mechanism proposed and rate constants for the key steps that mediate the oxidation.

Emerging inflammatory bowel disease demographics, phenotype, and treatment in South Asia, South-East Asia, and Middle East: Preliminary findings from the Inflammatory Bowel Disease-Emerging Nations' Consortium.

BACKGROUND AND AIM: Inflammatory bowel disease (IBD) is emerging in the newly industrialized countries of South Asia, South-East Asia, and the Middle East, yet epidemiological data are scarce. METHODS: We performed a cross-sectional study of IBD demographics, disease phenotype, and treatment across 38 centers in 15 countries of South Asia, South-East Asia, and Middle East. Intergroup comparisons included gross national income (GNI) per capita. RESULTS: Among 10 400 patients, ulcerative colitis (UC) was twice as common as Crohn's disease (CD), with a male predominance (UC 6678, CD 3495, IBD unclassified 227, and 58% male). Peak age of onset was in the third decade, with a low proportion of elderly-onset IBD (5% age > 60). Familial IBD was rare (5%). The extent of UC was predominantly distal (proctitis/left sided 67%), with most being treated with mesalamine (94%), steroids (54%), or immunomodulators (31%). Ileocolic CD (43%) was the commonest, with low rates of perianal disease (8%) and only 6% smokers. Diagnostic delay for CD was common (median 12 months; interquartile range 5-30). Treatment of CD included mesalamine, steroids, and immunomodulators (61%, 51%, and 56%, respectively), but a fifth received empirical antitubercular therapy. Treatment with biologics was uncommon (4% UC and 13% CD), which increased in countries with higher GNI per capita. Surgery rates were 0.1 (UC) and 2 (CD) per 100 patients per year. CONCLUSIONS: The IBD-ENC cohort provides insight into IBD in South-East Asia and the Middle East, but is not yet population based. UC is twice as common as CD, familial disease is uncommon, and rates of surgery are low. Biologic use correlates with per capita GNI.

Efficacy of international web-based educational intervention in the detection of high-risk flat and depressed colorectal lesions higher (CATCH project) with a video: Randomized trial.

OBJECTIVES: Three subcategories of high-risk flat and depressed lesions (FDLs), laterally spreading tumors non-granular type (LST-NG), depressed lesions, and large sessile serrated lesions (SSLs), are highly attributable to post-colonoscopy colorectal cancer (CRC). Efficient and organized educational programs on detecting high-risk FDLs are lacking. We aimed to explore whether a web-based educational intervention with training on FIND clues (fold deformation, intensive stool/mucus attachment, no vessel visibility, and demarcated reddish area) may improve the ability to detect high-risk FDLs. METHODS: This was an international web-based randomized control trial that enrolled non-expert endoscopists in 13 Asian countries. The participants were randomized into either education or non-education group. All participants took the pre-test and post-test to read 60 endoscopic images (40 high-risk FDLs, five polypoid, 15 no lesions) and answered whether there was a lesion. Only the education group received a self-education program (video and training questions and answers) between the tests. The primary outcome was a detection rate of high-risk FDLs. RESULTS: In total, 284 participants were randomized. After excluding non-responders, the final data analyses were based on 139 participants in the education group and 130 in the non-education group. The detection rate of high-risk FDLs in the education group significantly improved by 14.7% (66.6-81.3%) compared with -0.8% (70.8-70.0%) in the non-education group. Similarly, the detection rate of LST-NG, depressed lesions, and large SSLs significantly increased only in the education group by 12.7%, 12.0%, and 21.6%, respectively. CONCLUSION: Short self-education focusing on detecting high-risk FDLs was effective for Asian non-expert endoscopists. (UMIN000042348).

New therapeutic activity of metabolic enhancer piracetam in treatment of neurodegenerative disease: Participation of caspase independent death factors, oxidative stress, inflammatory responses and apoptosis.

Piracetam, a nootropic drug that has been clinically used for decades but remains enigmatic due to no distinct understanding of its mechanism of action. The present study aimed to investigate the role of caspase independent pathway in piracetam mediated neuroprotection. LPS administration caused significant alterations in oxidative stress related parameters like glutathione, glutathione reductase and increased lipid peroxidation. LPS administration also caused augmented expression of inflammatory cytokines and astrocytes activation. Piracetam treatment offered significant protection against LPS induced oxidative and inflammatory parameters and inhibited astrocytes activation. LPS administration caused augmented level of reactive oxygen species and depleted mitochondrial membrane potential which were attenuated with piracetam treatment. This study for the first time demonstrates the role of caspase independent death factors in piracetam induced neuroprotective effects in rat brain. Translocation of mitochondrial resident apoptosis inducing factor and endonuclease G to nucleus through cytosol after LPS administration was significantly blocked with piracetam treatment. Further, LPS induced DNA fragmentation along with up regulated Poly [ADP-ribose] polymerase 1 (PARP1) levels were also inhibited with piracetam treatment. Apoptotic death was confirmed by the cleavage of caspase 3 as well as histological alteration in rat brain regions. LPS administration caused significantly increased level of cleaved caspase 3, altered neuronal morphology and decreased neuronal density which were restored with piracetam treatment. Collectively our findings indicate that piracetam offered protection against LPS induced inflammatory responses and cellular death including its antioxidative antiapoptotic activity with its attenuation against mitochondria mediated caspase independent pathway.

Updates on immunity and inflammation in Parkinson disease pathology.

Studies in the last decade have suggested the association of both neuroinflammatory processes and immune responses in Parkinson disease (PD) pathology. PD pathology is related to depleted dopamine levels, α-synuclein aggregation, and death of nigrostriatal dopaminergic neurons. Reports have suggested central and peripheral inflammation in the prodromal stage of the disease, which is sustained during disease progression. Alongside the activation of peripheral immune system exacerbates the dissonant central inflammatory responses and could contribute in synergistic neurodegeneration. Activated glial cells contribute significantly in the neuroinflammatory process during the occurrence of the disease and are also acknowledged as a hallmark of disease progression. However, the contribution of glial cells is not well defined in the context of neurodegeneration and neuroprotection. This review provides an overview of the roles of immune and inflammatory responses and their consequences in PD disease pathogenesis and also discusses possible therapeutic strategies for PD based on these findings.

Customizable engineered blood vessels using 3D printed inserts.

Current techniques for tissue engineering blood vessels are not customizable for vascular size variation and vessel wall thickness. These critical parameters vary widely between the different arteries in the human body, and the ability to engineer vessels of varying sizes could increase capabilities for disease modeling and treatment options. We present an innovative method for producing customizable, tissue engineered, self-organizing vascular constructs by replicating a major structural component of blood vessels - the smooth muscle layer, or tunica media. We utilize a unique system combining 3D printed plate inserts to control construct size and shape, and cell sheets supported by a temporary fibrin hydrogel to encourage cellular self-organization into a tubular form resembling a natural artery. To form the vascular construct, 3D printed inserts are adhered to tissue culture plates, fibrin hydrogel is deposited around the inserts, and human aortic smooth muscle cells are then seeded atop the fibrin hydrogel. The gel, aided by the innate contractile properties of the smooth muscle cells, aggregates towards the center post insert, creating a tissue ring of smooth muscle cells. These rings are then stacked into the final tubular construct. Our methodology is robust, easily repeatable and allows for customization of cellular composition, vessel wall thickness, and length of the vessel construct merely by varying the size of the 3D printed inserts. This platform has potential for facilitating more accurate modeling of vascular pathology, serving as a drug discovery tool, or for vessel repair in disease treatment.

Determinants of the efficiency of photon upconversion by triplet-triplet annihilation in the solid state: zinc porphyrin derivatives in PVA.

Spectroscopic, photophysical and computational studies designed to expose and explain the differences in the efficiencies of non-coherent photon upconversion (NCPU) by triplet-triplet annihilation (TTA) have been carried out for a new series of alkyl-substituted diphenyl and tetraphenyl zinc porphyrins, both in fluid solution and in solid films. Systematic variations in the alkyl-substitution of the phenyl groups in both the di- and tetraphenyl porphyrins introduces small, but well-understood changes in their spectroscopic and photophysical properties and in their TTA efficiencies. In degassed toluene solution TTA occurs for all derivatives and produces the fluorescent S2 product states in all cases. In PVA matrices, however, none of the di-phenylporphyrins exhibit measurable NCPU whereas all the tetraphenyl-substituted compounds remain upconversion-active. In PVA the NCPU efficiencies of the zinc tetraphenylporphyrins vary significantly with their steric characteristics; the most sterically crowded tetraphenyl derivative exhibits the greatest efficiency. DFT-D computations have been undertaken and help reveal the sources of these differences.

Astrocytes: inexplicable cells in neurodegeneration.

Astrocytes are the most explored non-neuronal cells in the brain under neurophysiological and neurodegenerative conditions. Extensive research has been done to understand their specific role during neuropathological conditions but still the existing findings could not conclude their mechanism of action and their specific role in neurodegenerative conditions. This review discusses their physiological and pathological roles, their activation, morphological alterations and their probable use in search of new therapeutic targets for the treatment of neurodegenerative diseases.

White light generation using Förster resonance energy transfer between 3-hydroxyisoquinoline and Nile Red.

Simple composite films consisting of a polymer blended with organic emitters have the potential for broad-band "white" light emission that can be used for general lighting applications. In the present work, a simple mixture of 3-hydroxyisoquinoline (HIQ) with Nile Red (NR) in a polymeric matrix of polyvinyl alcohol (PVA) is used to generate white light through a non-radiative excitation energy transfer (NREET) mechanism. NREET between HIQ and NR doped in PVA films is investigated using a combination of steady state and time resolved fluorescence spectroscopic methods. It is observed that NR has very weak fluorescence in the PVA film upon excitation at 400 nm, but upon mixing NR with HIQ, sensitized emission of NR is observed with decreased emission of HIQ. The behavior of the sensitized emission of NR is consistent with Förster resonance energy transfer (FRET) between the donor HIQ and acceptor NR. By adjusting the relative fractions of HIQ and NR in the films, the extent of FRET could be regulated and the overall film emission color could be manipulated to enable overall "white" (CIE color coordinates 0.34, 0.38) emission. The films showed excellent photostability with 405 nm diode illumination, along with mechanical flexibility, suggesting good potential utility as a down converting element for lighting applications.

Spectroscopic and Structural Studies of a Surface Active Porphyrin in Solution and in Langmuir-Blodgett Films.

Controlling aggregation of the dual sensitizer-emitter (S-E) zinc tetraphenylporphyrin (ZnTPP) is an important consideration in solid state noncoherent photon upconversion (NCPU) applications. The Langmuir-Blodgett (LB) technique is a facile means of preparing ordered assemblies in thin films to study distance-dependent energy transfer processes in S-E systems and was used in this report to control the aggregation of a functionalized ZnTPP on solid substrates. This was achieved by synthetic addition of a short polar tail to one of the pendant phenyl rings in ZnTPP in order to make it surface active. The surface active ZnTPP derivative formed rigid films at the air-water interface and exhibited mean molecular areas consistent with approximately vertically oriented molecules under appropriate film compression. A red shift in the UV-vis spectra as well as unquenched fluorescence emission of the LB films indicated formation of well-ordered aggregates. However, NCPU, present in the solution phase, was not observed in the LB films, suggesting that NCPU from ZnTPP as a dual S-E required not just a controlled aggregation but a specific orientation of the molecules with respect to each other.

Rapid processes for purification of capsular polysaccharides from Neisseria meningitidis serogroups A and C.

The glycoconjugate vaccines against Neisseria meningitidis are highly effective, however most of these vaccines are expensive and still out of reach in the developing world as well as the technical know-how and the set-up required for the consistent production of pure polysaccharide is limited. Our laboratory has developed rapid, efficient and scalable processes for the downstream purification of N. meningitidis serogroup A (MenA) and serogroup C (MenC) capsular polysaccharides (PS). The MenC-PS was purified with a novel 2-step procedure including de-O-acetylation and hydrophobic interaction chromatography whereas, MenA-PS was purified using a rapid method as compared to the prior art. The purified PSs were analyzed by various analytical tests including nuclear magnetic resonance, molecular weight, composition and purity analyses to meet desired specifications. Our results provide a proof of principle for the purification of MenA-PS and MenC-PS with reduced timelines.

Slow excited state phototautomerization in 3-hydroxyisoquinoline.

In the present work we report the spectral and photophysical properties of 3-hydroxyisoquinoline in various protic/aprotic solvents. Our steady state and time resolved fluorescence data indicates that in the monomer form of 3HIQ phototautomerization can take place in the excited state through excited state intramolecular proton, while as per earlier suggestions phototautomerization in 3HIQ occurs in dimer or complex (in the presence of acetic acid) form. Moreover, we find rather slow tautomerization (occurring on the nanosecond scale). It is found that proton transfer occurs both in the ground as well as excited states and is controlled by the polarity of the solvent.

NIR phosphorescence from decatungstate anions allows the conclusive characterization of its elusive excited triplet behaviour and kinetics.

The characterization of the triplet state of decatungstate (3DT*) and its NIR phosphorescence with lifetimes ∼100 ns in acetonitrile allow the easy determination of rate constants that are key to understanding its role in catalysis. The absence of oxygen quenching can now be understood as the excitation energy of 3DT* is lower than the energy of singlet oxygen.

Isolated visceral manifestation of Buerger's disease presenting as intestinal obstruction: a case report.

Introduction and importance: Buerger's disease is an uncommon segmental nonatherosclerotic vasculitis essentially affecting small to medium-sized arteries and veins of upper and lower extremities and can lead to limb amputation. Visceral vessel involvement is quite rare accounting for 2% of cases presenting with acute abdomen due to mesenteric ischemia. Moreover, isolated visceral involvement is even rare. Case presentation: A 42-year-old gentleman, a chronic smoker, presented with abdominal pain associated with nausea and vomiting and loose stool of 2 months duration. Magnetic resonance enterography revealed segmental circumferential wall thickening with stricture in the mid part of the jejunum with lymphadenopathy features of possible inflammatory bowel disease (Crohn's disease). Furthermore, intraoperative surgical findings were also suggestive of Crohn's disease. However, histologic findings were consistent with thromboangiitis obliterans. Discussion: Thromboangiitis obliterans can present with inflammatory vascular lesions without necrosis in the early stage to varying degrees of recanalisation, gangrene, and amputation in the late stage. It rarely involves the brain, heart, and abdominal viscera. The visceral involvement may be in the form of intestinal obstruction or mesenteric ischemia or can mimic Crohn's in a background of smoking. Conclusion: This case report will help to learn more about the rarer intestinal presentation of intestinal Buerger's disease. It can present with features of bowel ischemia, obstruction or Crohn's. So, histology would play a pivotal role in differentiating the diagnostic dilemma.