Characteristics and Risk Factors of Functional Dyspepsia Fulfilling the Rome IV Criteria Overlapping With Gastroesophageal Reflux Disease, Irritable Bowel Syndrome, and Functional Constipation in South China

Background/Aims

Functional dyspepsia (FD) overlapping with other gastrointestinal disorders are quite common. The characteristics of FD overlap in Chinese population with latest Rome IV criteria were unclear. This large-scale outpatient-based study assessed the characteristics of FD overlap in South China.

Methods

Consecutive FD patients visited the Gastroenterology Clinic at 2 tertiary medical centers in Hangzhou, China who fulfilled the Rome IV criteria were enrolled. Complete questionnaires related to the gastrointestinal symptoms (Rome IV criteria), Reflux Disease Questionnaire, anxiety and depression, quality of sleep and life, and demographic information were collected.

Results

Among the total of 3281 FD patients, 50.69% overlapped with gastroesophageal reflux disease, 21.46% overlapped with irritable bowel syndrome, 6.03% overlapped with functional constipation. FD overlap had higher proportion of single/divorced/widowed rate, high education level, being employed, drinking, night shift, unhealthy dietary habit than FD only (P < 0.05). They had higher frequency of consultation and economic burden, as well as lower scores in quality of life (P < 0.001). Multivariate logistic regression showed that increasing age, female, low body mass index, history of gastroenteritis, anxiety, depression, and poor sleep quality were independent risk factors for FD overlap.

Conclusions

FD overlap was quite common in China with high economic burden and poor quality of life, FD patients with history of gastroenteritis, anxiety, depression, and poor sleep quality were more likely to have overlap disorders. Awareness of the physical and psychosocial stressors in overlapping condition would help optimize the management of FD overlap in clinical practice.

Four-sample lactose hydrogen breath test for diagnosis of lactose malabsorption in irritable bowel syndrome patients with diarrhea

AIM: To validate 4-sample lactose hydrogen breath testing (4SLHBT) compared to standard 13-sample LHBT in the clinical setting.

METHODS: Irritable bowel syndrome patients with diarrhea (IBS-D) and healthy volunteers (HVs) were enrolled and received a 10 g, 20 g, or 40 g dose lactose hydrogen breath test (LHBT) in a randomized, double-blinded, controlled trial. The lactase gene promoter region was sequenced. Breath samples and symptoms were acquired at baseline and every 15 min for 3 h (13 measurements). The detection rates of lactose malabsorption (LM) and lactose intolerance (LI) for a 4SLHBT that acquired four measurements at 0, 90, 120, and 180 min from the same data set were compared with the results of standard LHBT.

RESULTS: Sixty IBS-D patients and 60 HVs were studied. The genotype in all participants was C/C-13910. LM and LI detection rates increased with lactose dose from 10 g, 20 g to 40 g in both groups (P < 0.001). 4SLHBT showed excellent diagnostic concordance with standard LHBT (97%-100%, Kappa​​ 0.815-0.942) with high sensitivity (90%-100%) and specificity (100%) at all three lactose doses in both groups.

CONCLUSION: Reducing the number of measurements from 13 to 4 samples did not significantly impact on the accuracy of LHBT in health and IBS-D. 4SLHBT is a valid test for assessment of LM and LI in clinical practice.

Discovery of small-molecule inhibitors of Bcl-2 through structure-based computer screening

Bcl-2 belongs to a growing family of proteins which regulates programmed cell death (apoptosis). Overexpression of Bcl-2 has been observed in 70% of breast cancer, 30-60% of prostate cancer, 80% of B-cell lymphomas, 90% of colorectal adenocarcinomas, and many other forms of cancer. Thereby, Bcl-2 is an attractive new anti-cancer target. Herein, we describe the discovery of novel classes of small-molecule inhibitors targeted at the BH3 binding pocket in Bcl-2. The three-dimensional (3D) structure of Bcl-2 has been modeled on the basis of a high-resolution NMR solution structure of Bcl-X(L), which shares a high sequence homology with Bcl-2. A structure-based computer screening approach has been employed to search the National Cancer Institute 3D database of 206 876 organic compounds to identify potential Bcl-2 small-molecule inhibitors that bind to the BH3 binding site of Bcl-2. These potential Bcl-2 small-molecule inhibitors were first tested in an in vitro binding assay for their potency in inhibition of the binding of a Bak BH3 peptide to Bcl-2. Thirty-five potential inhibitors were tested in this binding assay, and seven of them were found to have a binding affinity (IC(50) value) from 1.6 to 14.0 microM. The anti-proliferative activity of these seven active compounds has been tested using a human myeloid leukemia cell line, HL-60, which expresses the highest level of Bcl-2 protein among all the cancer cell lines examined. Compound 6 was the most potent compound and had an IC(50) value of 4 microM in inhibition of cell growth using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Five other compounds had moderate activity in inhibition of cell growth. Compound 6 was further evaluated for its ability to induce apoptosis in cancer cells. It was found that 6 induces apoptosis in cancer cells with high Bcl-2 expression and its potency correlates with the Bcl-2 expression level in cancer cells. Furthermore, using NMR methods, we conclusively demonstrated that 6 binds to the BH3 binding site in Bcl-X(L). Our results showed that small-molecule inhibitors of Bcl-2 such as 6 modulate the biological function of Bcl-2, and induce apoptosis in cancer cells with high Bcl-2 expression, while they have little effect on cancer cells with low or undetectable levels of Bcl-2 expression. Therefore, compound 6 can be used as a valuable pharmacological tool to elucidate the function of Bcl-2 and also serves as a novel lead compound for further design and optimization. Our results suggest that the structure-based computer screening strategy employed in the study is effective for identifying novel, structurally diverse, nonpeptide small-molecule inhibitors that target the BH3 binding site of Bcl-2.

Synthesis and evaluation of the sunflower derived trypsin inhibitor as a potent inhibitor of the type II transmembrane serine protease, matriptase

We report here the synthesis of a 14-amino acid long bicyclic peptide, previously isolated from sunflower seeds. This peptide, termed sunflower trypsin inhibitor (SFTI-1), is one of the most potent naturally occurring small-molecule trypsin inhibitors. In addition to inhibiting trypsin, the synthetic SFTI-1 is also a very potent inhibitor, with a K(i) of 0.92nM, of the recently identified epithelial serine protease, termed 'matriptase'.

Functional preference of the constituent amino acid residues in a phage-library-based nonphosphorylated inhibitor of the Grb2-SH2 domain

A nonphosphorylated disulfide-bridged peptide, cyclo(Cys-Glu1-Leu-Tyr-Glu-Asn-Val-Gly-Met-Tyr9-Cys)-amide (termed G1) has been identified, by phage library, that binds to the Grb2-SH2 domain but not the src SH2 domain. Synthetic G1 blocks the Grb2-SH2 domain association (IC50 of 15.5 microM) with natural phosphopeptide ligands. As a new structural motif that binds to the Grb2-SH2 domain in a pTyr-independent manner, the binding affinity of G1 is contributed by the highly favored interactions of its structural elements interacting with the binding pocket of the protein. These interactions involve side-chains of amino acids Glu1, Tyr3, Glu4, Asn5, and Met8. Also a specific conformation is required for the cyclic peptide when bound to the protein. Ala scanning within G1 and molecular modeling analysis suggest a promising model in which G1 peptide binds in the phosphotyrosine binding site of the Grb2-SH2 domain in a beta-turn-like conformation. Replacement of Tyr3 or Asn5 with Ala abrogates the inhibitory activity of the peptide, indicating that G1 requires a Y-X-N consensus sequence similar to that found in natural pTyr-containing ligands, but without Tyr phosphorylation. Significantly, the Ala mutant of Glu1, i.e. the amino acid N-terminal to Y3, remarkably reduces the binding affinity. The position of the Glu1 side-chain is confirmed to provide a complementary role for pTyr3, as demonstrated by the low micromolar inhibitory activity (IC50 = 1.02 microM) of the nonphosphorylated peptide 11, G1(Gla1), in which Glu1 was replaced by gamma-carboxy-glutamic acid (Gla).

The Arf GTPase-activating protein ASAP1 regulates the actin cytoskeleton

Arf family GTP-binding proteins are best characterized as regulators of membrane traffic, but recent studies indicate an additional role in cytoskeletal organization. An Arf GTPase-activating protein of the centaurin beta family, ASAP1 (also known as centaurin beta4), binds Arf and two other known regulators of the actin cytoskeleton, the tyrosine kinase Src and phosphatidylinositol 4,5-bisphosphate. In this paper, we show that ASAP1 localizes to focal adhesions and cycles with focal adhesion proteins when cells are stimulated to move. Overexpression of ASAP1 altered the morphology of focal adhesions and blocked both cell spreading and formation of dorsal ruffles induced by platelet-derived growth factor (PDGF). On the other hand, ASAP1, with a mutation that disrupted GTPase-activating protein activity, had a reduced effect on cell spreading and increased the number of cells forming dorsal ruffles in response to PDGF. These data support a role for an Arf GTPase-activating protein, ASAP1, as a regulator of cytoskeletal remodeling and raise the possibility that the Arf pathway is a target for PDGF signaling.

Structural requirements for Tyr in the consensus sequence Y-E-N of a novel nonphosphorylated inhibitor to the Grb2-SH2 domain

The phage library derived, nonphosphorylated and thioether-cyclized peptide, termed G1TE, cyclo(CH(2)CO-Glu(1)-Leu-Tyr(3)-Glu-Asn-Val-Gly-Met-Tyr-Cys(10))-amid e, represents a new structural motif that binds to the Grb2-SH2 domain in a pTyr-independent manner, with an IC(50) of 20 microM. The retention of binding affinity is very sensitive with respect to peptide ring-size alterations and Ala mutations. We demonstrated previously that the Glu(1) side chain and its closely related analogs partially compensate for the absence of the phosphate functionality on Tyr(3), and, based on molecular modeling, these acidic side-chains complex with the Arg67 and Arg86 side-chains of the protein in the binding cavity. In this study we judiciously altered and incorporated various natural and unnatural amino acids as Tyr replacements within the -YEN- motif, and we demonstrate the functional importance and structural requirement of Tyr(3) for effective binding of this novel non-phosphorylated ligand to the Grb2-SH2 domain. The phenyl side-chain moiety and a polar functional group with specific orientation in position Y(3) of the peptide are particularly required. Using SPR binding assays, a submicromolar inhibitor (IC(50) = 0.70 microM) was obtained when Glu(1) was replaced with alpha-aminoadipate and Tyr(3) was replaced with 4-carboxymethyl-Phe, providing peptide 14, G1TE(Adi(1), cmPhe(3)). Peptide 14 also inhibited Grb2/p185(erb)(B-2) protein association in cell homogenates of erbB-2-overexpressing MDA-MA-453 cancer cells at near one micromolar concentrations.

Significant compensatory role of position Y-2 conferring high affinity to non-phosphorylated inhibitors of Grb2-SH2 domain

Systematic modification of amino acid at position Y-2 of a library-derived non-phosporylated thioether-cyclized peptide, cyclo(CH2CO-Glu2-Leu-Tyr0-Glu-Asn-Val-Gly-Met-Tyr-Cys) -amide, aided by molecular modeling, demonstrates that the Glu(-2) sidechain compensates for the absence of Tyr0 phosphorylation in retaining effective binding to Grb2-SH2 domain. Replacement of Glu(-2) with gamma-carboxyglutamic acid produced a high affinity inhibitor, the first example with submicromolar affinity (IC50 = 640 nM).

A p21(Waf1/Cip1)carboxyl-terminal peptide exhibited cyclin-dependent kinase-inhibitory activity and cytotoxicity when introduced into human cells

In the present study, we report the cyclin-dependent kinase (Cdk)-inhibitory activity of a series of p21waf1/cip1 (p21) peptide fragments spanning the whole protein against the cyclin D1/Cdk4 and cyclin E/Cdk2 enzymes. The most potent p21 peptide tested in our initial peptide series, designated W10, spanned amino acids 139 to 164, a region of p21 that has been found independently to bind to proliferating cell nuclear antigen and also to inhibit Cdk activity. We go on to report the importance of putative beta-strand and 3(10)-helix motifs in the W10 peptide for cyclin-dependent kinase-inhibitory activity. We also describe the cellular activity of W10 and derivatives that were chemically linked to an antennapedia peptide, the latter segment acting as a cell membrane carrier. We found that the W10AP peptide exhibited growth inhibition that resulted from necrosis in human lymphoma CA46 cells. Furthermore, regions in the W10 peptide responsible for Cdk-inhibition were also important for the degree of this cellular activity. These studies provide insights that may eventually, through further design, yield agents for the therapy of cancer.

Two cellulolytic Clostridium species: Clostridium cellulosi sp. nov. and Clostridium cellulofermentans sp. nov

Two cellulolytic clostridia, one thermophilic and the other mesophilic, were isolated and characterized. Cells of the thermophile are gram-negative rods that are motile with lophotrichous flagella and spherical terminal endospores which swell the cells. The optimum growth temperature is 55 to 60 degrees C, with a range of 40 to 65 degrees C. The deoxyribonucleic acid composition is 35 mol% G + C. The name Clostridium cellulosi sp. nov. is proposed. The type strain is AS 1.1777. Cells of the mesophile are gram negative and motile with peritrichous flagella and terminal oval or spherical spores which swell the cells. The deoxyribonucleic acid composition is 34 mol% G + C. The name Clostridium cellulofermentans sp. nov. is proposed. The type strain is AS 1.1775. Both C. cellulosi AS 1.1777 and C. cellulofermentans AS 1.1775 are deposited in the China Committee for Culture Collection of Microorganisms, Institute of Microbiology, Academia Sinica, Beijing, People's Republic of China.