Effect of age and cytoskeletal elements on the indentation-dependent mechanical properties of chondrocytes.

Articular cartilage chondrocytes are responsible for the synthesis, maintenance, and turnover of the extracellular matrix, metabolic processes that contribute to the mechanical properties of these cells. Here, we systematically evaluated the effect of age and cytoskeletal disruptors on the mechanical properties of chondrocytes as a function of deformation. We quantified the indentation-dependent mechanical properties of chondrocytes isolated from neonatal (1-day), adult (5-year) and geriatric (12-year) bovine knees using atomic force microscopy (AFM). We also measured the contribution of the actin and intermediate filaments to the indentation-dependent mechanical properties of chondrocytes. By integrating AFM with confocal fluorescent microscopy, we monitored cytoskeletal and biomechanical deformation in transgenic cells (GFP-vimentin and mCherry-actin) under compression. We found that the elastic modulus of chondrocytes in all age groups decreased with increased indentation (15-2000 nm). The elastic modulus of adult chondrocytes was significantly greater than neonatal cells at indentations greater than 500 nm. Viscoelastic moduli (instantaneous and equilibrium) were comparable in all age groups examined; however, the intrinsic viscosity was lower in geriatric chondrocytes than neonatal. Disrupting the actin or the intermediate filament structures altered the mechanical properties of chondrocytes by decreasing the elastic modulus and viscoelastic properties, resulting in a dramatic loss of indentation-dependent response with treatment. Actin and vimentin cytoskeletal structures were monitored using confocal fluorescent microscopy in transgenic cells treated with disruptors, and both treatments had a profound disruptive effect on the actin filaments. Here we show that disrupting the structure of intermediate filaments indirectly altered the configuration of the actin cytoskeleton. These findings underscore the importance of the cytoskeletal elements in the overall mechanical response of chondrocytes, indicating that intermediate filament integrity is key to the non-linear elastic properties of chondrocytes. This study improves our understanding of the mechanical properties of articular cartilage at the single cell level

SOST Inhibits Prostate Cancer Invasion.

Inhibitors of Wnt signaling have been shown to be involved in prostate cancer (PC) metastasis; however the role of Sclerostin (Sost) has not yet been explored. Here we show that elevated Wnt signaling derived from Sost deficient osteoblasts promotes PC invasion, while rhSOST has an inhibitory effect. In contrast, rhDKK1 promotes PC elongation and filopodia formation, morphological changes characteristic of an invasive phenotype. Furthermore, rhDKK1 was found to activate canonical Wnt signaling in PC3 cells, suggesting that SOST and DKK1 have opposing roles on Wnt signaling in this context. Gene expression analysis of PC3 cells co-cultured with OBs exhibiting varying amounts of Wnt signaling identified CRIM1 as one of the transcripts upregulated under highly invasive conditions. We found CRIM1 overexpression to also promote cell-invasion. These findings suggest that bone-derived Wnt signaling may enhance PC tropism by promoting CRIM1 expression and facilitating cancer cell invasion and adhesion to bone. We concluded that SOST and DKK1 have opposing effects on PC3 cell invasion and that bone-derived Wnt signaling positively contributes to the invasive phenotypes of PC3 cells by activating CRIM1 expression and facilitating PC-OB physical interaction. As such, we investigated the effects of high concentrations of SOST in vivo. We found that PC3-cells overexpressing SOST injected via the tail vein in NSG mice did not readily metastasize, and those injected intrafemorally had significantly reduced osteolysis, suggesting that targeting the molecular bone environment may influence bone metastatic prognosis in clinical settings

The spectrum of gastric cancer as seen in a large quaternary hospital in KwaZulu-Natal, South Africa

Background. Gastric cancer (GC) is the fifth most commonly diagnosed cancer in the world, with the third-highest associated mortality. It has a varying geographical, ethnic and socioeconomic distribution.Objective. To assess the presentation and management of GC in the Durban metropolitan area, South Africa.Methods. A retrospective review of 131 patients treated at the quaternary Inkosi Albert Luthuli Central Hospital in Durban from 2009 to 2014 was performed.Results. The 131 patients were predominantly black African (n=59, 45.0%) and Indian (n=63, 48.1%). Gender was evenly distributed, with 72 males (55.0%) and 59 females (45.0%). The average age of the patients was 60 years (standard deviation 13.3). More than 70% were in advanced stages of cancer and were treated conservatively. There was no significant relationship between body mass index (BMI) and the position of the tumour (p=0.175). Creatinine and albumin levels differed significantly between the genders (p<0.001 and p=0.01, respectively).Conclusions. GC appears to have a disproportionately high prevalence among Indians in Durban, and the prevalence of GC appears to be slightly higher among males. Both these observations may simply reflect referral patterns and warrant further investigation. More than 70% of patients presented with advanced-stage disease, and anaemia was common. No relationship was found between BMI and the location of the tumour, although most of the cancers were in the body and distal part of the stomach

Dibenzyl penta­thio­dicarbonate

In the title compound, C16H14S5, the non-bonded intra­molecular distances between the non-terminal S atoms are 2.808 (16) and 2.784 (16) Å, shorter than the typical distance of 2.9 Å. One phenyl ring participates in an offset π-π inter­action with another phenyl ring related by a centre of inversion; the inter­planar distance is 3.41 (2) Å. The crystal structure also exhibits edge-to-face C—H⋯π stacking of the phenyl rings, thus forming a herring-bone packing motif

Nanocomposite Scaffold for Chondrocyte Growth and Cartilage Tissue Engineering: Effects of Carbon Nanotube Surface Functionalization

The goal of this study was to assess the long-term biocompatibility of single-wall carbon nanotubes (SWNTs) for tissue engineering of articular cartilage. We hypothesized that SWNT nanocomposite scaffolds in cartilage tissue engineering can provide an improved molecular-sized substrate for stimulation of chondrocyte growth, as well as structural reinforcement of the scaffold\u27s mechanical properties. The effect of SWNT surface functionalization (-COOH or -PEG) on chondrocyte viability and biochemical matrix deposition was examined in two-dimensional cultures, in three-dimensional (3D) pellet cultures, and in a 3D nanocomposite scaffold consisting of hydrogels + SWNTs. Outcome measures included cell viability, histological and SEM evaluation, GAG biochemical content, compressive and tensile biomechanical properties, and gene expression quantification, including extracellular matrix (ECM) markers aggrecan (Agc), collagen-1 (Col1a1), collagen-2 (Col2a1), collagen-10 (Col10a1), surface adhesion proteins fibronectin (Fn), CD44 antigen (CD44), and tumor marker (Tp53). Our findings indicate that chondrocytes tolerate functionalized SWNTs well, with minimal toxicity of cells in 3D culture systems (pellet and nanocomposite constructs). Both SWNT-PEG and SWNT-COOH groups increased the GAG content in nanocomposites relative to control. The compressive biomechanical properties of cell-laden SWNT-COOH nanocomposites were significantly elevated relative to control. Increases in the tensile modulus and ultimate stress were observed, indicative of a tensile reinforcement of the nanocomposite scaffolds. Surface coating of SWNTs with -COOH also resulted in increased Col2a1 and Fn gene expression throughout the culture in nanocomposite constructs, indicative of increased chondrocyte metabolic activity. In contrast, surface coating of SWNTs with a neutral -PEG moiety had no significant effect on Col2a1 or Fn gene expression, suggesting that the charged nature of the -COOH surface functionalization may promote ECM expression in this culture system. The results of this study indicate that SWNTs exhibit a unique potential for cartilage tissue engineering, where functionalization with bioactive molecules may provide an improved substrate for stimulation of cellular growth and repair

Elucidating the Antimycobacterial Mechanism of Action of Decoquinate Derivative RMB041 Using Metabolomics

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), still remains one of the leading causes of death from a single infectious agent worldwide. The high prevalence of this disease is mostly ascribed to the rapid development of drug resistance to the current anti-TB drugs, exacerbated by lack of patient adherence due to drug toxicity. The aforementioned highlights the urgent need for new anti-TB compounds with different antimycobacterial mechanisms of action to those currently being used. An N-alkyl quinolone; decoquinate derivative RMB041, has recently shown promising antimicrobial activity against Mtb, while also exhibiting low cytotoxicity and excellent pharmacokinetic characteristics. Its exact mechanism of action, however, is still unknown. Considering this, we used GCxGC-TOFMS and well described metabolomic approaches to analyze and compare the metabolic alterations of Mtb treated with decoquinate derivative RMB041 by comparison to non-treated Mtb controls. The most significantly altered pathways in Mtb treated with this drug include fatty acid metabolism, amino acid metabolism, glycerol metabolism, and the urea cycle. These changes support previous findings suggesting this drug acts primarily on the cell wall and secondarily on the DNA metabolism of Mtb. Additionally, we identified metabolic changes suggesting inhibition of protein synthesis and a state of dormancy

Malignant and pre-malignant oesophageal pathology in a South African teaching hospital

BACKGROUND: South Africa (SA) has one of the highest global incidences of squamous cell carcinoma of the oesophagus (SCC). A decreasing incidence of oesophageal SCC in SA has been suggested. The study aimed to assess whether the incidence of these malignant histopathological subtypes has changed in this setting. METHOD: A retrospective review of histopathological reports on pre-malignant and malignant oesophageal lesions over three time periods (TP), namely: 2003-4 (TP1), 2008-9 (TP2) and 2013-14 (TP3) was carried out at Inkosi Albert Luthuli Central Hospital, Durban, South Africa. RESULTS: A total of 1341 specimen reports were retrieved. TP1-3 consisted of 514 (39.3%), 320 (24.5%) and 474 (36.2%) patients respectively. Six hundred and forty-nine patients were male (48.3%), 642 were female (47.8%) and 50 were not specified. i.e. a sex ratio of 1.01:1. The mean age was 60.8 (± 11.8). There were 1197 Black patients (91.5%), 66 Asian (5.1%), 25 White (1.9%), 9 mixed ancestry (0.7%), and 11 of unknown race (0.8%). SCC was the most common cancer 1098 (89.1%) followed by adenocarcinoma (AC) 69 (5.6%). The ratio of SCC to AC remained fairly consistent over the total time period. Seventy-four oesophageal resections were performed with a yearly average resection rate of only 5.6%. CONCLUSION: SCC is still the most prevalent oesophageal cancer (OC) without an increase in the ratio of AC to SCC. The diagnosis of squamous cell dysplasia is concordant with previously cited rates. Barrett's oesophagitis remains uncommon. Resection rates for OC are low but similar to other South African referring centers

Hand-foot-and-mouth disease caused by coxsackievirus A6 in a patient infected with HIV

Hand, foot and mouth disease (HFMD) is common in children ≤ 5 years of age, and is mainly caused by enterovirus 71 and coxsackievirus A16 (CVA6). A 12-year-old boy on treatment for human immunodeficiency virus (HIV) presented to an HIV clinic with fever and a rash on the palms and soles. The syphilis test were negative. Enterovirus was identified from a stool sample by PCR and characterised as as coxsackievirus A6(CVA6). The patient completely recovered a week later. CVA6 has recently been associated with HFMD. This case highlights the significance of the laboratory confirmation of suspected HFMD cases aand phylogenetic analysis of the identified virus.http://www.sajei.co.za/index.php/SAJEIam201

The spectrum of gastric cancer as seen in a large quaternary hospital in KwaZulu-Natal, South Africa

Background. Gastric cancer (GC) is the fifth most commonly diagnosed cancer in the world, with the third-highest associated mortality. It has a varying geographical, ethnic and socioeconomic distribution.Objective. To assess the presentation and management of GC in the Durban metropolitan area, South Africa.Methods. A retrospective review of 131 patients treated at the quaternary Inkosi Albert Luthuli Central Hospital in Durban from 2009 to 2014 was performed.Results. The 131 patients were predominantly black African (n=59, 45.0%) and Indian (n=63, 48.1%). Gender was evenly distributed, with 72 males (55.0%) and 59 females (45.0%). The average age of the patients was 60 years (standard deviation 13.3). More than 70% were in advanced stages of cancer and were treated conservatively. There was no significant relationship between body mass index (BMI) and the position of the tumour (p=0.175). Creatinine and albumin levels differed significantly between the genders (p<0.001 and p=0.01, respectively).Conclusions. GC appears to have a disproportionately high prevalence among Indians in Durban, and the prevalence of GC appears to be slightly higher among males. Both these observations may simply reflect referral patterns and warrant further investigation. More than 70% of patients presented with advanced-stage disease, and anaemia was common. No relationship was found between BMI and the location of the tumour, although most of the cancers were in the body and distal part of the stomach

Elucidating the Antimycobacterial Mechanism of Action of Ciprofloxacin Using Metabolomics

Abstract: In the interest of developing more effective and safer anti-tuberculosis drugs, we used a GCxGC-TOF-MS metabolomics research approach to investigate and compare the metabolic profiles of Mtb in the presence and absence of ciprofloxacin. The metabolites that best describe the differences between the compared groups were identified as markers characterizing the changes induced by ciprofloxacin. Malic acid was ranked as the most significantly altered metabolite marker induced by ciprofloxacin, indicative of an inhibition of the tricarboxylic acid (TCA) and glyoxylate cycle of Mtb. The altered fatty acid, myo-inositol, and triacylglycerol metabolism seen in this group supports previous observations of ciprofloxacin action on the Mtb cell wall. Furthermore, the altered pentose phosphate intermediates, glycerol metabolism markers, glucose accumulation, as well as the reduction in the glucogenic amino acids specifically, indicate a flux toward DNA (as well as cell wall) repair, also supporting previous findings of DNA damage caused by ciprofloxacin. This study further provides insights useful for designing network whole-system strategies for the identification of possible modes of action of various drugs and possibly adaptations by Mtb resulting in resistanc