Single bout of vibration-induced hamstrings fatigue reduces quadriceps inhibition and coactivation of knee muscles after anterior cruciate ligament (ACL) reconstruction

Persistent quadriceps strength deficits in individuals with anterior cruciate ligament reconstruction (ACLr) have been attributed to arthrogenic muscle inhibition (AMI). The purpose of the present study was to investigate the effect of vibration-induced hamstrings fatigue on AMI in patients with ACLr. Eight participants with unilateral ACLr (post-surgery time: M = 46.5, SD = 23.5 months; age: M = 21.4, SD = 1.4 years) and eight individuals with no previous history of knee injury (age: M = 22.5, SD = 2.5 years) were recruited. A fatigue protocol, consisting of 10 min of prolonged local hamstrings vibration, was applied to both the ACLr and control groups. The central activation ratio (CAR) of the quadriceps was measured with a superimposed burst of electrical stimulation, and hamstrings/quadriceps coactivation was assessed using electromyography (EMG) during isometric knee extension exercises, both before and after prolonged local vibration. For the ACLr group, the hamstrings strength, measured by a load cell on a purpose-built chair, was significantly (P = 0.016) reduced about 14.5%, indicating fatigue was actually induced in the hamstrings. At baseline, the ACLr group showed a trend (P = 0.051) toward a lower quadriceps CAR (M = 93.2%, SD = 6.2% versus M = 98.1%, SD = 1.1%) and significantly (P = 0.001) higher hamstrings/quadriceps coactivation (M = 15.1%, SD = 6.2% versus M = 7.5%, SD = 4.0%) during knee extension compared to the control group. The fatigue protocol significantly (P = 0.001) increased quadriceps CAR (from M = 93.2%, SD = 6.2% to M = 97.9%, SD = 2.8%) and significantly (P = 0.006) decreased hamstrings/quadriceps coactivation during knee extension (from M = 15.1%, SD = 6.2% to M = 9.5%, SD = 4.5%) in the ACLr group. In conclusion, vibration-induced hamstrings fatigue can alleviate AMI of the quadriceps in patients with ACLr. This finding has clinical implications in the management of recovery for ACLr patients with quadriceps strength deficits and dysfunction.     

Thymol alleviates AGEs-induced podocyte injury by a pleiotropic effect via NF-κB-mediated by RhoA/ROCK signalling pathway

ABSTRACT

Advanced glycation end products (AGE) are those of the most powerful pathogenic factors that related to diabetic complications. In our study, we investigated the beneficial effects of thymol on AGE induced cell injury and apoptosis in human podocytes (HPCs) and attempted to clarify its mechanisms. Our results revealed that stimulation with AGE could significantly activate RhoA/NF-κB pathway. Results showed thymol could markedly suppress inflammatory responses, cell apoptosis and disordered cytoskeleton. Also thymol restored the expression of podocin, restrained migration capacity. Western blot analysis indicated that it could restore the expression of RhoA, ROCK and vimentin, nephrin, podocin and p65 and IκBα phosphorylation. Moreover, si-RhoA also suppressed the expression of pro-inflammatory cytokines, ROCK, and vimentin and the phosphorylation of p65 and IκBα. In conclusion, thymol inhibits AGE-induced cell injury in HPCs by suppressing the RhoA-NF-κB pathway and may be apromising therapeutic agent.     

Identification of 5H-chromeno[3,4-c]pyridine and 6H-isochromeno[3,4-c]pyridine derivatives as potent and selective dual ROCK inhibitors

A novel series of 5H-chromeno[3,4-c]pyridine, 6H-isochromeno[3,4-c]pyridine and 6H-isochromeno[4,3-d]pyrimidine derivatives as dual ROCK1 and ROCK2 inhibitors is described. Optimization led to compounds with sub-nanomolar inhibitory affinity for both kinases and excellent kinome selectivity. Compound 19 exhibited ROCK1 and ROCK2 IC₅₀ of 0.67 nM and 0.18 nM respectively.     

N-Sulfonyl dipeptide nitriles as inhibitors of human cathepsin S: In silico design,synthesis and biochemical characterization

A library of cathepsin S inhibitors of the dipeptide nitrile chemotype, bearing a bioisosteric sulfonamide moiety, was synthesized. Kinetic investigations were performed at four human cysteine proteases, i.e. cathepsins S, B, K and L. Compound 12 with a terminal 3-biphenyl sulfonamide substituent was the most potent (K_i = 4.02 nM; selectivity ratio cathepsin S/K = 5.8; S/L = 67) and 24 with a 4′-fluoro-4-biphenyl sulfonamide substituent the most selective cathepsin S inhibitor (K_i = 35.5 nM; selectivity ratio cathepsin S/K = 57; S/L = 31). In silico design and biochemical evaluation emphasized the impact of the sulfonamide linkage on selectivity and a possible switch of P2 and P3 substituents with respect to the occupation of the corresponding binding sites of cathepsin S.     

Mdm2 inhibitors as a platform for the design of P-glycoprotein inhibitors

Chemoresistance is thought to be the cause of low treatment efficacy and mortality in more than 90% of patients with advanced cancer. The activation of drug efflux by P-glycoprotein is the key mechanism of resistance. All known P-gp inhibitors are used only in the combination therapy. We propose a new approach based on the multitarget rational design of drugs, which possess both the antitumor and efflux pump inhibitory activity. In this work, the principle possibility of combining the ability to inhibit P-gp and p53-Mdm2 protein-protein interaction in one structure is considered. The biological activity of a number of known and newly synthesized compounds was evaluated using cell lines with different p53 status. The possibility of using computer modeling for the search for P-glycoprotein inhibitors among Mdm2 inhibitors was analyzed; P-gp interaction site and binding modes of substrates and inhibitors were identified. The results obtained in cells that have the native balance of drug resistance and sensitivity showed the ability of the cells to both actively throw out xenobiotics and to lose this ability using P-gp inhibitors. The data obtained indicate that Mdm2 inhibitors are a promising platform for the development of multitarget drugs that can overcome tumor resistance by inhibiting the P-glycoprotein activity.     

Ansamycin derivatives from the marine-derived Streptomyces sp. SCSGAA 0027 and their cytotoxic and antiviral activities

Fourteen ansamycin derivatives including seven new herbimycins G–L (1–6) and divergolide O (7), and seven known analogues were isolated from a culture broth of the marine-derived Streptomyces sp. SCSGAA 0027. Their complete structures were determined by detailed analysis of spectroscopic data and quantum chemical calculations. Compounds 1–5 and 7 featured an additional eight-membered O-heterocycle that has rarely been reported for ansamycins, and the Z,Z- and E,E-configurations for Δ²,Δ⁴ were reported for the first time in geldanamycin analogues. Compound 1 exhibited weak inhibition activity towards Hsp90α with an IC₅₀ value of 96 µM, 2–5 showed mild cytotoxicity against four human cancer cell lines with IC₅₀ values ranging from 13 μM to 86 μM, and 7 had moderate anti-HSV-1 activity with an IC₅₀ value of 19 µM and very weak cytotoxicity towards Vero cell. The possible biosynthetic pathways for 1–5 were proposed. And their structure-bioactivity relationship was also discussed.     

Synthesis and anti-proliferative activity of a novel 1,2,3-triazole tethered chalcone acetamide derivatives

A new series of 1,2,3-triazole tethered chalcone acetamide derivatives (7a-c & 8a-r) have been synthesized in excellent yields and their structures were determined by analytical and spectral (FT-IR, ¹H NMR, ¹³C NMR & HRMS) studies. The newly synthesized derivatives were evaluated for their cytotoxic activity against four human cancer cell lines, such as HeLa (Human cervical cancer), A549 (Human alveolar adenocarcinoma), MCF-7 (Human breast adenocarcinoma) and SKNSH (Human brain cancer). Among them, compound 7c exhibited good anti-proliferation activity with HeLa (IC₅₀ 7.41 + 0.8 μM), SKNSH (IC₅₀ 8.68 + 1.1 μM), MCF-7 (IC₅₀ 9.76 + 1.3 μM) and MDA-MB-231, while compounds 7a and 7b showed promising anti-proliferation against above four human cancer cell lines with IC₅₀ 7.95–11.62 μM, respectively, compared with the standard drug Doxorubicin. We explored the probable key active site and binding mode interactions in HDAC8 (PDB ID:3SFH) and EHMT2 (PDB ID:3K5K) proteins. The docking results are complementary to the experimental observations.     

Transient rho-associated coiled-coil containing kinase (ROCK) inhibition on human retinal pigment epithelium results in persistent Rho/ROCK downregulation

Retinal pigment epithelium (RPE) cells is the outermost layer of the retina and RPE dysfunction is a key factor in the disease pathogenesis of age-related macular degeneration (AMD). Transplantation therapy using induced pluripotent stem cell (iPSC)-derived RPEs has recently received much attention as a treatment for AMD. Preserving these cells under the best possible conditions is important, and preservation methods using Y-27632 have been reported. Rho-associated coiled-coil containing kinase (ROCK) inhibitors are known to inhibit cell death, emerging as important drug candidates for stem cell differentiation and regenerative medicine. However, it has recently been shown that ROCK inhibitors may have a vasodilatory effect on human retinal arterioles, a side effect that should ideally be avoided in RPE transplantation. Although ROCK inhibitors hold great potential, optimizing efficacy while minimizing adverse reactions is critical for translation into a clinical treatment. We examined the effect of transient exposure of RPE cells to ROCK inhibitor Y-27632 to determine whether the extracellular presence of the drug is necessary for ongoing Rho/ROCK downregulation. Human RPE cells were subcultured as a suspension for 4 h in drug-free medium following exposure to Y-27632 for 2 h. A Y-27632 concentration of >10 μM improved cell survival beyond 4 h and cell proliferation in recovery culture medium. ROCK2 expression levels were specifically downregulated by Y-27632 in the Rho/ROCK signaling pathway. In conclusion, we demonstrated that the effect of Y-27632 is not dependent on its extracellular availability and can last beyond the 2 h of exposure. The lasting Rho/ROCK signaling pathway downregulation by Y-27632 suggests that RPE cell transplantation with ROCK inhibitor-free media is possible, which can minimize side effects to host tissue and have wider implications for transplantation methods requiring ROCK inhibition.