OBJECTIVETo investigate the protective effects of glycyl-glutamine dipeptide supplement on the function of myocardial dynamics in severely burned rats, and to explore its mechanism.

METHODSOne hundred and thirty-six Wistar rats were randomly divided into five groups: i. e, control group (C, n = 8, without burns), burn group (B, n = 32), Gln group (Gln, n = 32), Gly group (Gly, n = 32) and Gly-Gln group (Gly-Gln, n = 32). The rats in the latter four groups were respectively treated with tyrosine (1.5 g x kg(-1) x d(-1)), glutamine (1.0 g x kg(-1) x d(-1)) and tyrosine (0.5 g x kg(-1) x d(-1)), glycine (0.5 g x kg(-1) x d(-1)) and tyrosine (1.0 g x kg(-1) x d(-1)), and Glycyl-glutamine dipeptide (1.5 g x kg(-1) x d(-1)) after receiving a 30% TBSA full-thickness burn on the back. Glutathione (GSH), adenosine monophosphate (AMP), adenosine diphosphate (ADP), adenosine triphosphate (ATP), cell energy charge (EC) and the index of myocardial dynamics (ASOP, AODP, LVSP, + dp/dtmax) were measured at 12, 24, 48, 72 post-burn hours (PBH).

RESULTSThe content of GSH, ATP, EC and the level of aortic systolic pressure (ASOP), aortic diastolic blood pressure (AODP), left ventricular end diastolic pressure (LVEDP) and maximum rate of intraventricular pressure rise/down (+ dp/dtmax) in B, Gln, Gly, Gly-Gln groups were obviously lower than those in C group (P < 0.01), while the levels of AMP and ADP showed an opposite tendency. Compared with B group, the above indices were ameliorated. The content of GSH (72.7 +/- 1.7) micromol/g in Gly-Gln group at 12 PBH was obviously higher than that in Gln group (67.8 +/- 3.8) micromol/g (P < 0.01). The levels of EC and AOSP were obviously higher in Gly-Gln group than that in Gln group (P < 0.01). The level of GSH, EC, AOSP in Gly-Gln groups were obviously higher than those in Gly group at 48 PBH.

CONCLUSIONGlycyl-glutamine dipeptide, Gly and Gln supplementation after burns can improve the content of GSH and high energy phosphate compound, and suppress the decline of myocardial dynamics function. The effects of Glycyl-glutamine dipeptide is better than single Gly or Gln, indicating that the protective effect on myocardial function after severe burns by Gln and Gly is synergistic.

Animals ; Burns ; drug therapy ; metabolism ; Dipeptides ; pharmacology ; Glutathione ; metabolism ; Glycine ; Myocytes, Cardiac ; drug effects ; metabolism ; Random Allocation ; Rats ; Rats, Wistar

This study was to investigate the effects of DAPT (N-[N-(3,5-difluorophenacetyl-L:-alanyl)]-S-phenylglycine-butyl ester) on cell cycle, apoptosis, differentiation and expansion of hematopoietic stem cells (HSC) of mouse and to elucidate the possible mechanisms. The mRNA expressions of cell cycle-related genes p18, p21, p27, CDK1, CDK2, CDK4, CDK6, and apoptosis-related genes Bcl-2, Bcl-xl, mcl-1, Bax, Bim, p53, Puma were measured by real-time PCR. The cell cycle and apoptosis of Lin(-)c-kit(+)Sca-1(+) marked cells and CD34(-)Lin(-)c-kit(+)Sca-1(+) marked cells in bone marrow cells were detected by flow cytometry. The differentiation level of HSC was determined by single cell culture. The expansion of HSC were measured with long-term culture. The results indicated that the mRNA expression of the cell cycle related-genes CDK1, CDK2, CDK4, CDK6, p27 in Lin(-) c-kit(+)Sca-1(+) marked cells increased (P < 0.05), the expression of p18, p21 decreased (P < 0.05), the expression of the apoptosis related-genes Bcl-2, Bcl-xl, Bax, p53, Puma in Lin(-) c-kit(+)Sca-1(+) marked cells increased (P < 0.05), the expression of Bim decreased (P < 0.05), the expression of Mcl-1 had not changed (P > 0.05) after treatment with DAPT 1 µmol/L for 5 d. The changes of cell cycle of Lin(-)c-kit(+)Sca-1(+) marked cells in bone marrow had no statistical significance after treatment with DAPT 1 µmol/L for 5 d, CD34(-)Lin(-)c-kit(+)Sca-1(+) marked cells in bone marrow at G(0) phase decreased and at G(1) phase increased after treatment with DAPT 1 µmol/L for 5 d (P < 0.05); the apoptotic fractions of Lin(-) c-kit(+) Sca-1(+) marked cells and CD34(-)Lin(-)c-kit(+)Sca-1(+) marked cells in bone marrow increased after treatment with DAPT 1 µmol/L for 5 d (P < 0.05). The changes of colony number, average number of cells in wells and their differentiation had no statistical significance (P > 0.05) after treatment with DAPT 1 µmol/L for 10 d. Expansion of HSC in bone marrow of mouse decreased after treatment with DAPT 1 µmol/L for 3 d. It is concluded that DAPT not only enhances the exhaustion of CD34(-)Lin(-)c-kit(+)Sca-1(+) marked cells in bone marrow cells of mouse, but also enhances the apoptosis of Lin(-)c-kit(+)Sca-1(+) marked cells and CD34(-)Lin(-)c-kit(+)Sca-1(+) marked cells in bone marrow cells of mouse. DAPT also reduces the expansion of HSC. However, the changes of survival and differentiation of single CD34(-)Lin(-)c-kit(+)Sca-1(+) marked cells in mouse bone marrow cells have no statistical significance.
Animals ; Apoptosis Regulatory Proteins ; metabolism ; Bone Marrow Cells ; metabolism ; Cell Cycle Proteins ; metabolism ; Dipeptides ; pharmacology ; Hematopoietic Stem Cells ; drug effects ; metabolism ; Mice ; Mice, Inbred C57BL ; Signal Transduction

This study aims to investigate the effect of γ-Secretase Inhibitor DAPT, (N-[N-(3,5-Difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester), on the differentiation of neural precursor cells and the production of neurons in the neural precursor cell line GE6. GE6 was cultured in medium with 4 μmol/L DAPT added as the experimental group and the untreated medium separately as the control group. After 4 days of differentiation, we carried out the following experiments. We used immuno-fluorescent staining to observe the ratio of Tuj1, GFAP and O4 positive cells. We also used qRT-PCR to detect the effect of the DAPT on Tuj1 and GFAP mRNA transcription in the GE6. The results of immuno-fluorescent staining indicated that the Tuj1 ratio of experimental group was higher compared to that of the control group, but the GFAP and O4 ratio of experimental group was lower than that of the control group. The differences were statistically significant (P < 0.05). The result of qRT-PCR was in accordance with immunofluorescent staining results. It was well concluded that DAPT could promote the neurogenic differentiation of neural precursor cell line rather than leading to gliogenic differentiation. More neurons could be obtained for transplantation with the addition of DAPT.
Amyloid Precursor Protein Secretases ; antagonists & inhibitors ; Animals ; Cell Differentiation ; drug effects ; Cell Line ; Dipeptides ; pharmacology ; Neural Stem Cells ; drug effects ; Neurons ; Rats

OBJECTIVETo study the effect of L-alanyl-L-glutamine (Ala-Gln) on the levels of insulin-like growth factor-1 (IGF-1) and IGF-1 receptor (IGF-1R) in the intestinal tissues of low-birth-weight (LBW) newborn rats with hypoxia/reoxygenation-induced intestinal injury.

METHODSPregnant rats were fed with or without smoking. The rats born by those fed without smoking were included in group A; for the rats born by those fed with smoking, normal-birth-weight rats were included in group B, and LBW rats were randomly divided into control group (group C), hypoxia/reoxygenation (H/R) group (group D), and Ala-Gln group (group E). Each group consisted of 24 newborn rats. The rats in groups D and E received H/R treatment twice a day for three consecutive days to establish an intestinal injury model; the rats in group E were intraperitoneally injected with Ala-Gln (10 ml/kg) before daily H/R treatment, while those in groups C and D were given an equal dose of normal saline by intraperitoneal injections. On days 4, 7, and 10 after birth, 8 rats were sacrificed in each group to collect intestinal tissues. The IGF-1 levels in intestinal tissues were measured using ELISA, and IGF-1R levels were measured by immunohistochemistry.

RESULTSThere were no significant differences in IGF-1 and IGF-1R levels between groups A and B at all time points. The levels of IGF-1 and IGF-1R in group C kept increasing, were higher than those in other groups on day 7 (P<0.05), and reached a normal level on day 10, without significant differences compared with those in groups A and B. Group D had significantly lower IGF-1 and IGF-1R levels than group C at all time points (P<0.05). The levels of IGF-1 and IGF-1R in group E were lower than those in group C on days 4 and 7 (P<0.05), but they increased to approximately the levels in group C and were significantly higher than those in group D on day 10.

CONCLUSIONSIntrauterine and postnatal hypoxia may induce intestinal injury in LBW newborn rats, and parenteral administration of high-dose Ala-Gln can reduce hypoxia-induced intestinal injury. Therefore, Ala-Gln has a protective effect against hypoxia-induced intestinal injury.

Animals ; Birth Weight ; Dipeptides ; pharmacology ; Female ; Hypoxia ; metabolism ; Insulin-Like Growth Factor I ; analysis ; Intestines ; chemistry ; Male ; Pregnancy ; Rats ; Rats, Sprague-Dawley ; Receptor, IGF Type 1 ; analysis

OBJECTIVETo study the effect of matrix metalloproteinases inhibitor GM6001 in suppressing scar tissue formation in the filtering passage after glaucoma filtration surgery.

METHODSTwenty-four pigmented rabbits (48 eyes) underwent trabeculectomy followed by subconjunctival injection of GM6001 in the right eye (treated eyes) and injection of PBS in the left eye (control) once a day. The intraocular pressure was monitored postoperatively and proliferating cell nuclear antigen (PCNA)- and α-smooth muscle actin (α-SMA)-positive cells in the filtering pathway were detected using immunohistochemistry.

RESULTSOn postoperative days 7, 14, 21, and 28, the intraocular pressure was significantly lower in the treated eyes (GM6001) than in the control eyes (P<0.01). The counts of PCNA- and α-SMA-positive cells were also significantly lowered in the treated than in the control eyes (P<0.01).

CONCLUSIONGM6001 can inhibit excessive proliferation of the fibroblasts in the filtering pathway to suppress scar tissue formation and prolong the existence of the functional filtration bleb in rabbits.

Actins ; metabolism ; Animals ; Cicatrix ; pathology ; prevention & control ; Dipeptides ; pharmacology ; Filtering Surgery ; adverse effects ; Glaucoma ; surgery ; Intraocular Pressure ; Postoperative Complications ; Proliferating Cell Nuclear Antigen ; metabolism ; Rabbits

To establish a new amino acid structure descriptor that can be applied to polypeptide quantitative structure activity relationship (QSAR) studies, a new descriptor, SVRDF, was derived from a principal components analysis of a matrix of 150 radial distribution function index of amino acids. The scale was then applied in three panels of peptide QSAR that were molded by partial least squares regression. The obtained models with the correlation coefficients (R2(cum)), cross-validation correlation coefficients (Q2(cum)) were 0.766 and 0.724 for 48 bitter tasting dipeptides; 0.941 and 0.811 for 21 oxytocin analogues; 0.996 and 0.919 for 20 thromboplastin inhibitors. Satisfactory results showed that information related to biological activity can be systemically expressed by SVRDF scales, which may be an useful structural expression methodology for the study of peptides QSAR.
Amino Acid Sequence ; Amino Acids ; chemistry ; Dipeptides ; chemistry ; pharmacology ; Least-Squares Analysis ; Models, Chemical ; Oxytocin ; analogs & derivatives ; chemistry ; pharmacology ; Peptides ; chemistry ; pharmacology ; Principal Component Analysis ; methods ; Quantitative Structure-Activity Relationship ; Thromboplastin ; antagonists & inhibitors ; chemistry ; pharmacology

BACKGROUNDPaclitaxel (PAC) is the first-line chemotherapy drug for most breast cancer patients, but clinical studies showed that some breast cancer patients were insensitive to PAC, which led to chemotherapy failure. It was reported that Notch1 signaling participated in drug resistance of breast cancer. Here, we show whether Notch1 expression is related to PAC sensitivity of breast cancer.

METHODSWe employed Notch1 siRNA and Notch1 inhibitor, N-[N-(3,5-difluorophenacetyl)-1-alanyl]-S-phenylglycine t-butylester (DAPT), to down regulate Notch1 expression in human breast cancer cells MDA-MB-231, and detected the inhibition effect by Western blotting and reverse trans cription-polymerase chain reaction, respectively. After 24 hours exposure to different concentration of PAC (0, 1, 5, 10, 15, 20, and 25 µg/ml), the viability of the control group and experimental group cells was tested by MTT. We also examined the expression of Notch1 in PAC sensitive and nonsensitive breast cancer patients, respectively by immunohistochemistry (IHC). The PAC sensitivity of breast cancer patients were identified by collagen gel droplet embedded culture-drug sensitivity test (CD-DST).

RESULTSDown regulation of Notch1 expression by Notch1siRNA interference or Notch1 inhibitor increased the PAC sensitivity in MDA-MB-231 cells (P < 0.05). Also, the expression of Notch1 in PAC sensitive patients was much lower than that of PAC non-sensitive patients (P < 0.01).

CONCLUSIONNotch1 expression has an effect on PAC sensitivity in breast cancer patients, and the inhibition of Notch1 increases paclitaxel sensitivity to human breast cancer.

Antineoplastic Agents ; pharmacology ; Breast Neoplasms ; metabolism ; Cell Line, Tumor ; Cell Survival ; drug effects ; Dipeptides ; pharmacology ; Humans ; Immunohistochemistry ; Paclitaxel ; pharmacology ; Receptor, Notch1 ; antagonists & inhibitors ; metabolism ; Reverse Transcriptase Polymerase Chain Reaction

OBJECTIVEIt is known that Notch signal is very important to vascular remodeling during the process of embryonic development, vessel repair and tumor growth, but there are few studies about pulmonary vascular remodeling in pulmonary hypertension. This study was to explore the effect of inhibiting Notch signal on pulmonary vascular remodeling induced by angiotensin II.

METHODSVessel strips taken from healthy Wistar rats were co-cultured with extrogenous angiotensin II and the potent smooth muscle cell proliferation stimulators for 7 days. Vascular wall thickness, proliferating cell nuclear antigen (PCNA) positive cell rate and caspase-3 positive cell rate were examined in vessel strips. Then some vessel strips were cultured with angiotensin II and γ-secretase inhibitor DAPT, a Notch signaling inhibitor for 7 days. The levels of Notch 1 to 4 receptor and HERP1/2 mRNA were ascertained by FQ-PCR.

RESULTSAngiotensin II stimulation in the cultured normal pulmonary arteries resulted in an increase in the vascular medial thickness by nearly 50%, and a significant increase in the PCNA positive cell rate and a decrease in the caspase-3 positive cell rate. DAPT treatment did not result in the alterations of Notch 1 to 4 receptor levels, but decreased remarkably HERP1 and HERP2 mRNA expression. DAPT treatment also decreased angiotensin II-induced vascular medial thickness and PCNA positive cell rate and increased caspase-3 positive cell rate.

CONCLUSIONSInhibiting Notch signal by γ-secretase inhibitor may lead to the suppression of pulmonary vascular remodeling induced by angiotensin II, suggesting that the inhibition of Notch signal pathway might be a novel strategy for the treatment of pulmonary hypertension.

Angiotensin II ; pharmacology ; Animals ; Dipeptides ; pharmacology ; Proliferating Cell Nuclear Antigen ; analysis ; Pulmonary Artery ; drug effects ; pathology ; Rats ; Rats, Wistar ; Receptors, Notch ; antagonists & inhibitors ; physiology ; Signal Transduction ; drug effects ; physiology

Romipeptides A and B (1 and 2), two new romidepsin derivatives, and three known compounds, chromopeptide A (3), romidepsin (4) and valine-leucine dipeptide (5) were isolated from the fermentation broth of Chromobacterium violaceum No. 968. Their structures were elucidated by interpretation of their UV, HR-ESI-MS and NMR spectra. The absolute configuration of compound 1 and 2 were established by single crystal X-ray diffraction analysis. Compounds 1-5 were evaluated for their anti-proliferative activities against three human cancer cell lines, SW620, HL60, and A549. The results showed most of these compounds exhibited antitumor activities in vitro, in which compound 2 displayed potent cytotoxicity to SW620, HL60 and A549 cell lines, with IC of 12.5, 6.7 and 5.7 nmol·L, respectively.
Antineoplastic Agents ; chemistry ; pharmacology ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Cell Survival ; drug effects ; Chemistry Techniques, Analytical ; Chromobacterium ; metabolism ; Depsipeptides ; chemistry ; pharmacology ; Dipeptides ; chemistry ; Drug Screening Assays, Antitumor ; Fermentation ; Humans ; Molecular Structure ; Peptides, Cyclic ; chemistry

The aim of this study was to explore the effect of DAPT (N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycinet-butyl ester) on proliferation in vitro of human multiple myeloma cell line RPMI8226 and its underlying mechanism. The proliferation of RPMI8226 cells was detected by CCK-8 method; flow cytometry was employed to assay the cell apoptosis rate;the expressions of Notch1 and Hes1 proteins were detected by Western blot. The results indicated that the proliferation of human RPMI8226 cells significantly decreased after treatment with DAPT 0.5 - 5.0 µmol/L for 24 - 72 h (P < 0.05) in a concentration- and time-dependent manner. DAPT significantly induced apoptosis of RPMI8226 cells (P < 0.05). The expressions of Notch1 and Hes1 proteins were gradually downregulated with the increase of DAPT concentration. It is concluded that the DAPT can inhibit the proliferation of RPMI8226 cells, which may be related with the down-regulation of the protein expression of Notchl and Hes1.
Apoptosis ; drug effects ; Basic Helix-Loop-Helix Transcription Factors ; metabolism ; Cell Line, Tumor ; Cell Proliferation ; drug effects ; Dipeptides ; pharmacology ; Homeodomain Proteins ; metabolism ; Humans ; Multiple Myeloma ; metabolism ; pathology ; Receptor, Notch1 ; metabolism ; Transcription Factor HES-1