Intestinal dysbacteriosis contributes to decreased intestinal mucosal barrier function and increased bacterial translocation

The purpose of this study was to determine the effect of colistin-induced intestinal dysbacteriosis on intestinal mucosal barrier function and bacterial translocation in a mouse model. Colistin or saline was administered orally for 7 days, and populations of viable organisms from the caecal mucosa and its content, the ileal segments, the mesenteric lymph nodes (MLNs) and the internal organs were prepared for examination. In the intestinal dysbacteriosis model, intestinal barrier dysfunction was observed and associated with increased bacterial translocation to extraintestinal sites. The extent of bacterial translocation to the MLNs and internal organs in the colistin group was significantly higher than in the saline group. Colistin-induced intestinal dysbacteriosis was shown to injure the intestinal mucosa barrier function and increase bacterial dislocation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Colistin has been reported to be effective in selective digestive decontamination (SDD), which is an infection prevention measure used in the treatment of certain patients in intensive care. We are the first to report that colistin-induced intestinal dysbacteriosis can injure intestinal mucosal barrier function and increase bacterial translocation, whereas a high dose of colistin does not damage the intestinal mucosal barrier in germ-free (GF) mice raised in a GF environment. These results may indicate that prolonged use of a high dose of a SDD medication should be carefully considered.

MicroRNA-106b-5p boosts glioma tumorigensis by targeting multiple tumor suppressor genes

Aberrant expression of microRNAs (miRNAs) has been implicated in cancer initiation and progression. However, little is known about the potential role of miRNAs in glioma tumorigenesis. In this study, we found that miRNA-106b-5p was significantly upregulated in glioma tumor samples and cell lines compared with normal brain tissues, and its expression level correlated with the pathological grading. Overexpression of miR-106b-5p in glioma tumor cells significantly promoted cell proliferation, although inhibited cell apoptosis in vitro and in vivo. In contrast, knockdown of miR-106b-5p significantly inhibited cell proliferation, although enhanced cell apoptosis. Mechanistic study revealed that two target genes, retinoblastoma-like 1 (RBL1) and RBL2, were involved in miR-106b-5p's regulation of cell proliferation and one target gene, caspase-8 (CASP8), mediated miR-106b-5p's regulation of apoptosis. We also investigated the function of the three targets in glioma tumorigenesis by RNA interference manipulation and demonstrated that knockdown of these target genes led to cell proliferation enhancement or cell apoptosis inhibition in vitro. More interestingly, the expression levels of these targets were significantly downregulated in glioma samples and knockdown of these targets in glioma cells inhibited the xenograft tumor formation in vivo. Moreover, we verified the regulation function of miR-106b-5p and its targets on cell proliferation and apoptosis of the primary cultured astrocytes isolated from glioma tumor samples and healthy controls. Collectively, our findings show the critical roles of miR-106b-5p and its targets, RBL1, RBL2 and CASP8, in glioma tumorigenesis and provide potential candidates for malignant glioma therapy.

Christianson syndrome protein NHE6 modulates TrkB endosomal signaling required for neuronal circuit development

Neuronal arborization is regulated by cell-autonomous and nonautonomous mechanisms including endosomal signaling via BDNF/TrkB. The endosomal Na⁺/H⁺ exchanger 6 (NHE6) is mutated in a new autism-related disorder. NHE6 functions to permit proton leak from endosomes, yet the mechanisms causing disease are unknown. We demonstrate that loss of NHE6 results in overacidification of the endosomal compartment and attenuated TrkB signaling. Mouse brains with disrupted NHE6 display reduced axonal and dendritic branching, synapse number, and circuit strength. Site-directed mutagenesis shows that the proton leak function of NHE6 is required for neuronal arborization. We find that TrkB receptor colocalizes to NHE6-associated endosomes. TrkB protein and phosphorylation are reduced in NHE6 mutant neurons in response to BDNF signaling. Finally, exogenous BDNF rescues defects in neuronal arborization. We propose that NHE6 mutation leads to circuit defects that are in part due to impoverished neuronal arborization that may be treatable by enhanced TrkB signaling.

Ileal mucosa-associated--but not ileal digesta--bacterial profiles in grower pigs are influenced by nutrition and use of antibiotics for weaner pigs

A longitudinal study was conducted in pigs to evaluate the effect of nutrition and use of antibiotics for weaner pigs on ileal bacterial microbiota. Forty-eight pigs were weaned at 21 ± 2 d of age and fed a high complexity diet (High) or low complexity diet (Low) with chlortetracycline (A+) or without chlortetracycline (A-) for 6 wk. All pigs received the same grower diet thereafter. Pigs were killed at week 2, 4, and 8 and ileal digesta as well as a 40-cm section of the distal ileum were taken for extraction of digesta and mucosa-associated bacteria, respectively. Total DNA was extracted using a commercially available kit and PCR amplicons were generated using HDA1-GC and HDA2 primers against the V3 region of the 16S rRNA gene. Denaturing gradient gel electrophoresis (DGGE) of PCR amplicons was used for separation of distinct bacteria communities. Similarities of PCR-DGGE profiles were analyzed with Bionumerics software and the degree of similarity represented by a similarity coefficient. The DNA bands were compared using a positional tolerance of 0.5%. In the digesta, HighA-, LowA+, and LowA- were 47.6, 63.6, and 58.8% similar, respectively, at week 2 and 64.0, 69.2, and 66.7% similar, respectively, at week 4. Digesta bacteria were 90.9 (HighA-) and 85.7% (LowA-) similar to HighA+ at week 8 but due to a smiling edge of the DGGE gel, the profile for LowA+ was deemed inappropriate for similarity analysis. In the mucosa, HighA-, LowA+, and LowA- were 58.8, 80.0 and 44.4% similar, respectively, compared to HighA+ at week 2; 81.5, 75.0, and 88.9% similar, respectively, at week 4; and 81.8, 76.2, and 78.3% similar, respectively, at week 8. The bacterial profile was more similar between weeks 2 and 4 in the digesta than in the mucosa but more similar between weeks 4 and 8 in the mucosa than in the digesta. Postweaning nutrition may have a long-term effect on ileal mucosa-associated--but not ileal digesta--microbiota profiles.

First result from the Alpha Magnetic Spectrometer on the International Space Station: precision measurement of the positron fraction in primary cosmic rays of 0.5-350 GeV

A precision measurement by the Alpha Magnetic Spectrometer on the International Space Station of the positron fraction in primary cosmic rays in the energy range from 0.5 to 350 GeV based on 6.8 × 10(6) positron and electron events is presented. The very accurate data show that the positron fraction is steadily increasing from 10 to ∼ 250  GeV, but, from 20 to 250 GeV, the slope decreases by an order of magnitude. The positron fraction spectrum shows no fine structure, and the positron to electron ratio shows no observable anisotropy. Together, these features show the existence of new physical phenomena.

Peripheral blood CD40-CD40L expression in human breast cancer

BACKGROUND

Breast cancer is the most common cancer in women. T cell-based immunotherapy for cancer has attracted much attention recently. CD40 and CD40L occupy an important position of specific immune response. In this paper, we want to study the role of co-stimulatory molecules CD40/CD40L and their clinical significance in peripheral blood of patients with breast cancer.

METHODS

Thirty breast cancer patients served as observation group, who were diagnosed as having infiltrating ductal breast cancer histopathologically, and 30 healthy as control group. Flow cytometric analysis was conducted to detect the expression of CD40 and CD40L on B and T lymphocytes in peripheral blood. The relationship between the CD40/CD40L expression levels and pathological grades was analyzed.

RESULTS

The expression levels of CD40/CD40L on B cells and T cells in breast cancer patients were significantly higher than those in the controls (all P < 0.001), and CD40/CD40L levels had a significant positive relationship with pathological grades (all P < 0.001).

CONCLUSIONS

The upregulated levels of co-stimulators CD40/CD40L on B cells and T cells may play an important role in the immune pathogenesis of breast cancer.

Imaging lipid droplet fusion and growth

Lipid droplets (LDs) are highly dynamic cellular organelles found in most eukaryotic cell types. In white adipocytes, LDs grow into a characteristic unilocular morphology that is well suited for its specialized role as an efficient energy storage organelle. Overexpansion of LDs in white adipocytes results in the development of obesity and insulin resistance. Besides its central role in lipid storage and mobilization, LDs play crucial roles in various cellular processes including virus packaging, host defense, protein storage, and degradation. CIDE proteins, in particular Fsp27, initiates a unique LD fusion process in adipocytes by clustering and enriching at LD contact site and promoting neutral lipid exchange and transfer between contacted LDs. Here, we summarize our approaches to quantitatively measure intracellular LD size and neutral lipid exchange between LDs. Utilization of these methods has greatly facilitated our understanding of molecular pathways governing LD growth in adipocytes.

Advanced or metastatic gastric cancer in elderly patients: clinicopathological, prognostic factors and treatments

PURPOSE

To analyze the clinicopathological features, prognostic factors, treatment efficacy and safety among elderly patients with advanced or metastatic gastric cancer.

METHODS

Three hundred and nineteen patients aged 65 years and older, diagnosed with advanced or metastatic gastric cancer, were followed and data were retrospectively collected, reviewed and analyzed.

RESULTS

The elderly patients carried specific clinicopathological characteristics. Body mass index (BMI), number of metastatic lesions, ascites, Karnofsky performance score (KPS), tumor differentiation grade, lactate dehydrogenase (LDH) level, local treatment, and chemotherapy were the independent prognostic factors. Serum LDH level was superior to the serum CEA level in the prognosis of advanced or metastatic gastric cancer in older patients. Cisplatin-based regimen, chemotherapy cycles, metastatic lesions, LDH level, and supraclavicular lymph node metastasis were the independent prognostic factors in 220 patients receiving chemotherapy. The toxicity was mild and tolerable.

CONCLUSION

KPS, BMI and a well-differentiated histopathology were factors favoring longer survival, whereas elevated serum LDH and a greater number of metastatic lesions were associated with poor prognosis among those elderly patients. Cisplatin-based chemotherapy provided survival benefits and mild toxicity.

Advanced or metastatic gastric cancer in elderly patients: clinicopathological, prognostic factors and treatments

PURPOSE

To analyze the clinicopathological features, prognostic factors, treatment efficacy and safety among elderly patients with advanced or metastatic gastric cancer.

METHODS

Three hundred and nineteen patients aged 65 years and older, diagnosed with advanced or metastatic gastric cancer, were followed and data were retrospectively collected, reviewed and analyzed.

RESULTS

The elderly patients carried specific clinicopathological characteristics. Body mass index (BMI), number of metastatic lesions, ascites, Karnofsky performance score (KPS), tumor differentiation grade, lactate dehydrogenase (LDH) level, local treatment, and chemotherapy were the independent prognostic factors. Serum LDH level was superior to the serum CEA level in the prognosis of advanced or metastatic gastric cancer in older patients. Cisplatin-based regimen, chemotherapy cycles, metastatic lesions, LDH level, and supraclavicular lymph node metastasis were the independent prognostic factors in 220 patients receiving chemotherapy. The toxicity was mild and tolerable.

CONCLUSION

KPS, BMI and a well-differentiated histopathology were factors favoring longer survival, whereas elevated serum LDH and a greater number of metastatic lesions were associated with poor prognosis among those elderly patients. Cisplatin-based chemotherapy provided survival benefits and mild toxicity.

DNA strand breaks occurring during apoptosis - their early insitu detection by the terminal deoxynucleotidyl transferase and nick translation assays and prevention by serine protease inhibitors

The appearance of DNA strand breaks during apoptosis was detected in individual cells, in relation to the cell cycle phase, by a novel assay based on labeling 3'-OH termini with biotinylated dUTP using exogenous terminal transferase or DNA polymerase. Apoptosis was induced in HL-60 cells by the DNA topoisomerase I and II inhibitors, and in rat thymocytes by prednisolone. Formation of strand breaks was prevented by the serine protease irreversible inhibitors diisopropyl fluorophosphate (DFP), L-1-tosylamido-2-phenylethyl chloromethyl ketone (TPCK), N-p-tosyl-L-lysine chloromethyl ketone (TLCK) and by the substrates N-alpha-tosyl-L-arginine methyl ester (TAME) and N-benzoyl-L-tyrosine ethyl ester (BTEE). The data indicate that initiation of DNA degradation during apoptosis is preceded by a proteolytic step and suggest that apoptosis starts with activation (e.g. by DNA lesions) of a serine protease which hydrolyses protein(s) associated with the internucleosomal linker DNA sections, thus increasing accessibility of linker DNA to the apoptosis-associated endonuclease.

Blocking p55PIK signaling inhibits proliferation and induces differentiation of leukemia cells

p55PIK, a regulatory subunit of phosphatidylinositol 3-kinases, promotes cell cycle progression by interacting with cell cycle modulators such as retinoblastoma protein (Rb) via its unique amino-terminal 24 amino-acid residue (N24). Overexpression of N24 specifically inhibits these interactions and leads to cell cycle arrest. Herein, we describe the generation of a fusion protein (Tat transactivator protein (TAT)-N24) that contains the protein transduction domain and N24, and examined its effects on the proliferation and differentiation of leukemia cells. TAT-N24 not only blocks cell proliferation but remarkably induces differentiation of leukemia cells in vitro and in vivo. Systemically administered TAT-N24 also significantly decreases growth of leukemia cell tumors in animal models. Furthermore, overexpression of p55PIK in leukemia cells leads to increased proliferation; however, TAT-N24 blocks this effect and concomitantly induces differentiation. There is significant upregulation of p55PIK mRNA and protein expression in leukemia cells from patients. TAT-N24 inhibits cell cycle progression and induces differentiation of bone marrow cells derived from patients with several different types of leukemia. These results show that cell-permeable N24 peptide induces leukemia cell differentiation and suggest that p55PIK may be a novel drug target for the treatment of hematopoetic malignancies.

Arctigenin, a natural compound, activates AMP-activated protein kinase via inhibition of mitochondria complex I and ameliorates metabolic disorders in ob/ob mice

AIMS/HYPOTHESIS

Arctigenin is a natural compound that had never been previously demonstrated to have a glucose-lowering effect. Here it was found to activate AMP-activated protein kinase (AMPK), and the mechanism by which this occurred, as well as the effects on glucose and lipid metabolism were investigated.

METHODS

2-Deoxyglucose uptake and AMPK phosphorylation were examined in L6 myotubes and isolated skeletal muscle. Gluconeogenesis and lipid synthesis were evaluated in rat primary hepatocytes. The acute and chronic effects of arctigenin on metabolic abnormalities were observed in C57BL/6J and ob/ob mice. Changes in mitochondrial membrane potential were measured using the J-aggregate-forming dye, JC-1. Analysis of respiration of L6 myotubes or isolated mitochondria was conducted in a channel oxygen system.

RESULTS

Arctigenin increased AMPK phosphorylation and stimulated glucose uptake in L6 myotubes and isolated skeletal muscles. In primary hepatocytes, it decreased gluconeogenesis and lipid synthesis. The enhancement of glucose uptake and suppression of hepatic gluconeogenesis and lipid synthesis by arctigenin were prevented by blockade of AMPK activation. The respiration of L6 myotubes or isolated mitochondria was inhibited by arctigenin with a specific effect on respiratory complex I. A single oral dose of arctigenin reduced gluconeogenesis in C57BL/6J mice. Chronic oral administration of arctigenin lowered blood glucose and improved lipid metabolism in ob/ob mice.

CONCLUSIONS/INTERPRETATION

This study demonstrates a new role for arctigenin as a potent indirect activator of AMPK via inhibition of respiratory complex I, with beneficial effects on metabolic disorders in ob/ob mice. This highlights the potential value of arctigenin as a possible treatment of type 2 diabetes.