Highly sensitive MR imaging agents that can accurately and rapidly monitor changes in pH would have diagnostic and prognostic value for many diseases. Here, we report an investigation of hyperpolarized 15N-pyridine derivatives as ultrasensitive pH-sensitive imaging probes. These molecules are easily polarized to high levels using standard dynamic nuclear polarization (DNP) techniques and their 15N chemical shifts were found to be highly sensitive to pH. These probes displayed sharp 15N resonances and large differences in chemical shifts (Δδ >90 ppm) between their free base and protonated forms. These favorable features make these agents highly suitable candidates for the detection of small changes in tissue pH near physiological values.

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Alterations in the microbiome are associated with the development of gastric cancer. Our study aimed to identify dysbiotic features in early gastric cancer (EC). The gastric microbiome was assessed in EC (n = 30), advanced gastric cancer (AC) (n = 30), and chronic gastritis (CG) (n = 60). The results demonstrated significant differences in the microbial profile and composition between EC and AC, suggesting alterations associated with gastric cancer progression. Linear discriminant analysis (LDA) effect size (LEfSe) analyses identified 32 bacterial genera that were associated with EC. Functional analyses of the gastric microbiome showed that the production of urease and synthesis of bacterial flagella were weakened in EC, while the glycolysis of fructose and hydrolysis of glycosides were enhanced. A classifier based on a random forest (RF) machine learning algorithm identified a microbial signature that distinguished EC from CG or AC with high accuracy. The correct identification of the signature was further validated in independent cohorts. This signature enriched of bacteria with varied abundance, high degree of bacterial interactions and carcinogenic potentials. Constrained principal coordinate analyses revealed that the presence of Helicobacter pylori and the cagA and vacA virulence genotypes influenced the structure of the gastric microbiome. To determine the impacts of host genetic variations on the gastric microbiome, six previously reported single nucleotide polymorphisms (SNPs) were examined. The minor allele of MUC1 rs4072037 was associated with an increased abundance of Ochrobactrum. The gastric microbiome altered in EC, which might be attributed in part to host genetic variations, H. pylori infection, bacterial virulence and environmental adaptations. The identified microbial signature could serve as biomarkers for clinical assessment of gastric cancer risk in high-risk patients.

Mitochondrial dysfunction is considered to be an important component of many metabolic diseases yet there is no reliable imaging biomarker for monitoring mitochondrial damage in vivo. A large prior literature on inter‐conversion of β‐hydroxybutyrate and acetoacetate indicates that the process is mitochondrial and that the ratio reflects a specifically mitochondrial redox state. Therefore, the conversion of [1,3‐13C]acetoacetate to [1,3‐13C]β‐hydroxybutyrate is expected to be sensitive to the abnormal redox state present in dysfunctional mitochondria. In this study, we examined the conversion of hyperpolarized (HP) 13C‐acetoacetate (AcAc) to 13C‐β‐hydroxybutyrate (β‐HB) as a potential imaging biomarker for mitochondrial redox and dysfunction in perfused rat hearts. Conversion of HP‐AcAc to β‐HB was investigated using 13C magnetic resonance spectroscopy in Langendorff‐perfused rat hearts in four groups: control, global ischemic reperfusion, low‐flow ischemic, and rotenone (mitochondrial complex‐I inhibitor)‐treated hearts. We observed that more β‐HB was produced from AcAc in ischemic hearts and the hearts exposed to complex I inhibitor rotenone compared with controls, consistent with the accumulation of excess mitochondrial NADH. The increase in β‐HB, as detected by 13C MRS, was validated by a direct measure of tissue β‐HB by 1H nuclear magnetic resonance in tissue extracts. The redox ratio, NAD+/NADH, measured by enzyme assays of homogenized tissue, also paralleled production of β‐HB from AcAc. Transmission electron microscopy of tissues provided direct evidence for abnormal mitochondrial structure in each ischemic tissue model. The results suggest that conversion of HP‐AcAc to HP‐β‐HB detected by 13C‐MRS may serve as a useful diagnostic marker of mitochondrial redox and dysfunction in heart tissue in vivo.

In lipid monolayers consisting of two phases, the competition between line tension and electrostatic repulsion can give rise to a stripe phase. The stability of this phase with respect to small harmonic distortions is analyzed. It is shown that the stripe phase is just marginally stable when the stripes are of equilibrium width. As soon as the stripes exceed this width, coupled long wavelength distortions are energetically favored.Intermediate results concerning the stability of a single edge and a single stripe are also presented. IntroductionPhospholipid monolayers at the air-water interface can be readily prepared and observed in a two-phase regime.' The coexisting phases, which appear as dark and light phases under the fluorescence microscope, form a variety of spatial structures, such as circular or near-circular domains, parallel stripes, or more irregular, wormlike structures. Such structures are thought to arise from a competition between line tension and electrostatic r e p~l s i o n .~-~ In the simplest possible macroscopic model, the total free energy of the monolayer contains a line tension term, due to the interfacial energy between the two phases, and an electrostatic term, due to the long range repulsion forces between surface dipoles:6 d-AT ' -where A is the line tension, ,u is the difference in the dipole densities of the two phases, and A is a cutoff parameter that keeps the double line integral from diverging. Note that P is the total length of the interface between the two phases. The double line integral, which has the form of the Biot-Savart law between current loops, is taken over the interface. Equilibrium structures are those which minimize the free energy, usually under the constraint that the area of each phase is fixed. Mathematically, this translates into a challenging problem in variational calculus. Minimization of the total free energy leads to an integrodifferential equation, which in the general case is intractable.A more promising approach has been to postulate certain simple geometries for the two phases. The geometric parameters that characterize such geometries are then varied until the free energy is minimized. For example, if one assumes that one phase exists as circular islands of equal radius in a sea of the majority phase, it is straightforward to determine the radius which minimizes the total free energy:7(2)Similarly, for a phase with alternating black and white stripes of equal width w , the equilibrium stripe width is found to be8(3)The next logical step in this approach is to subject these @ Abstract published in Advance ACS Abstracts, April 1, 1995.geometries to various distortions and see whether the total free energy is thereby increased or decreased. Accordingly, in previous work, we have studied both the stability of circular domains with respect to small harmonic distortions9 and large nonharmonic distortions1° and the stability of a straight edge with respect to small deformations." We now apply the same method of (lowest order) stability analysis to a stripe...

Ras homolog gene family member A (RhoA) has been identified as a critical regulator of tumor aggressive behavior. In this study, we assessed the role of RhoA in the mechanisms underlying growth, migration, and invasion of squamous cell carcinoma of tongue (TSCC). Stable RhoA knockdown of TSCC cell lines SCC-4 and CAL27 were achieved using Lentiviral transfection. The effects of RhoA depletion on cell migration, invasion, and cell proliferation were determined. The possible underlying mechanism of RhoA depletion on TSCC cell line was also evaluated by determining the expression of Galectin-3 (Gal-3), β-catenin, and matrix metalloproteinase-9 (MMP-9) in vivo. Meanwhile, the underlying mechanism of TSCC growth was studied by analysis of cyclin D1/2, p21CIP1/WAF1, and p27Kip1 protein levels. Immunohistochemical assessments were performed to further prove the alteration of Gal-3 and β-catenin expression. We found that, in mice injected with human TSCC cells in the tongue, RhoA levels were higher in primary tumors and metastasized lymph nodes compared with those in the normal tissues. Silencing of RhoA significantly reduced the tumor growth, decreased the levels of Gal-3, β-catenin, MMP-9, and cyclin D1/2, and increased the levels of p21CIP1/WAF1 and p27Kip1. In vitro, RhoA knockdown also led to inhibition of cell migration, invasion, and proliferation. Our data suggest that RhoA plays a significant role in TSCC progression by regulating cell migration and invasion through Wnt/β-catenin signaling pathway and cell proliferation through cell cycle regulation, respectively. RhoA might be a novel therapeutic target of TSCC.

Leishmaniasis, caused by the intracellular protozoan parasite Leishmania, remains an important neglected tropical infectious disease. Infection may be lethal if untreated. Currently, the available drugs for the disease are limited by high toxicity and drug resistance. There is an urgent need to develop novel anti-leishmanial strategies. Antimicrobial peptides (AMPs) have been described as the first-line immune defense against pathogenic microbes and are being developed as emerging anti-parasitic therapies. In the present study, we showed the anti-leishmanial activity of the synthetic 4-amino acid peptide lysine, aspartic acid, glutamic acid, and leucine (KDEL), the endoplasmic reticulum retention sequence, against Leishmania tarentolae promastigote and amastigote. Different concentrations of KDEL peptides were incubated with promastigotes, MTT viability assay, and promastigote assay were carried out. Macrophages infected with GFP-transfected L. tarentolae promastigotes were incubated with KDEL peptides, and the anti-amastigote activity of the KDEL peptides was measured by fluorescence microscopy. The damage of L. tarentolae was observed by light microscopy and electron microscopy. The cell apoptosis was analyzed using the Annexin V-FITC/PI apoptosis detection kit and mitochondrial membrane potential assay kit and by flow cytometry. Results showed that L. tarentolae was susceptible to KDEL peptides in a dose-dependent manner, and KDEL peptides disrupted the surface membrane integrity and caused cell apoptosis. In our study, we found for the first time an AMP KDEL from Pseudomonas aeruginosa and proved its significant therapeutic potential as a novel anti-leishmanial drug.