Melanoma therapeutics: a literature review

Melanoma is a relentless type of skin cancer which involves myriad signaling pathways which regulate many cellular processes. This makes melanoma difficult to treat, especially when identified late. At present, therapeutics include chemotherapy, surgical resection, biochemotherapy, immunotherapy, photodynamic and targeted approaches. These interventions are usually administered as either a single-drug or in combination, based on tumor location, stage, and patients’ overall health condition. Howe...     

Vancomycin-Variable Enterococcus faecium: In Vivo Emergence of Vancomycin Resistance in a Vancomycin-Susceptible Isolate

We report the emergence of vancomycin resistance in a patient colonized with a vanA-containing, vanRS-negative isolate of Enterococcus faecium which was initially vancomycin susceptible. This is a previously undescribed mechanism of drug resistance with diagnostic and therapeutic implications.     

Characterisation of the differences between hepatitis C virus genotype 3 and 1 glycoproteins

Sequence variation in the envelope E1 and E2 glycoproteins of hepatitis C virus (HCV) could account for differences in disease pathogenesis in patients infected with different genotypes. A cDNA encoding the structural region of the hepatitis C polyprotein was constructed to match the majority sequence of viral RNA extracted from a patient infected with genotype 3a (designated strain HCV3a-Gla). The principal differences predicted between E2 of HCV3a-Gla and the corresponding H77c genotype 1a protein were that the former contained six more amino acids (361 vs. 355), but it had one fewer glycosylation site. Expression studies showed that, in common with the H77c glycoproteins, E1 and E2 from HCV3a-Gla localised to the endoplasmic reticulum (ER) membrane in both Huh-7 and BHK tissue culture cells and interacted to form native complexes. Analysis of the cross-reactivity of antibodies raised against glycoproteins of genotype 1a strains showed that three of five monoclonal antibodies that recognise linear epitopes were able to detect E2 from strain HCV3a-Gla. However, neither conformational E2 antibodies nor antibodies raised against E1 were able to detect the HCV3a-Gla glycoproteins. In receptor binding assays, E2 of HCV3a-Gla consistently failed to bind CD81, a putative cell receptor for HCV. Absence of binding to CD81 and lack of recognition by most antibodies raised to genotype 1a glycoproteins indicate important differences between these glycoproteins representative of genotypes 3a and 1a. These may be pertinent to the differences in response to interferon therapy and the prevalence of steatosis reported in patients infected with these genotypes.     

Gene expression patterns and gene copy number changes in dermatofibrosarcoma protuberans

Dermatofibrosarcoma protuberans (DFSP) is an aggressive spindle cell neoplasm. It is associated with the chromosomal translocation, t(17:22), which fuses the COL1A1 and PDGFbeta genes. We determined the characteristic gene expression profile of DFSP and characterized DNA copy number changes in DFSP by array-based comparative genomic hybridization (array CGH). Fresh frozen and formalin-fixed, paraffin-embedded samples of DFSP were analyzed by array CGH (four cases) and DNA microarray analysis of global gene expression (nine cases). The nine DFSPs were readily distinguished from 27 other diverse soft tissue tumors based on their gene expression patterns. Genes characteristically expressed in the DFSPs included PDGF beta and its receptor, PDGFRB, APOD, MEOX1, PLA2R, and PRKCA. Array CGH of DNA extracted either from frozen tumor samples or from paraffin blocks yielded equivalent results. Large areas of chromosomes 17q and 22q, bounded by COL1A1 and PDGF beta, respectively, were amplified in DFSP. Expression of genes in the amplified regions was significantly elevated. Our data shows that: 1) DFSP has a distinctive gene expression profile; 2) array CGH can be applied successfully to frozen or formalin-fixed, paraffin-embedded tumor samples; 3) a characteristic amplification of sequences from chromosomes 17q and 22q, demarcated by the COL1A1 and PDGF beta genes, respectively, was associated with elevated expression of the amplified genes.     

Canonical TRP channels and mechanotransduction: from physiology to disease states

Mechano-gated ion channels play a key physiological role in cardiac, arterial, and skeletal myocytes. For instance, opening of the non-selective stretch-activated cation channels in smooth muscle cells is involved in the pressure-dependent myogenic constriction of resistance arteries. These channels are also implicated in major pathologies, including cardiac hypertrophy or Duchenne muscular dystrophy. Seminal work in prokaryotes and invertebrates highlighted the role of transient receptor potential (TRP) channels in mechanosensory transduction. In mammals, recent findings have shown that the canonical TRPC1 and TRPC6 channels are key players in muscle mechanotransduction. In the present review, we will focus on the functional properties of TRPC1 and TRPC6 channels, on their mechano-gating, regulation by interacting cytoskeletal and scaffolding proteins, physiological role and implication in associated diseases.     

Novel missense mutations and a 288-bp exonic insertion in PAX9 in families with autosomal dominant hypodontia

We describe the molecular analysis of three families with hypodontia involving primarily molar teeth and report two novel mutational mechanisms. Linkage analysis of two large families revealed that the hypodontia was linked to the PAX9 locus. These two families revealed missense mutations consisting of a glutamic acid substitution for lysine and a proline substitution for leucine within the paired domain of PAX9. A pair of identical twins affected with hypodontia in a third family demonstrated a 288-bp insertion within exon 2 that resulted in a putative frameshift mutation and a premature stop codon. The insertion was associated with the loss of 7-bp from exon 2. A block of 256-bp of sequence within the insertion was completely identical to downstream sequence from the second intron of the PAX9 gene. These studies extend the spectrum of mutations in PAX9 associated with hypodontia to include heretofore undescribed categories, including missense mutations.     

Bone and cartilage tissue constructs grown using human bone marrow stromal cells, silk scaffolds and rotating bioreactors

Human bone marrow contains a population of bone marrow stromal cells (hBMSCs) capable of forming several types of mesenchymal tissues, including bone and cartilage. The present study was designed to test whether large cartilaginous and bone-like tissue constructs can be selectively engineered using the same cell population (hBMSCs), the same scaffold type (porous silk) and same hydrodynamic environment (construct settling in rotating bioreactors), by varying the medium composition (chondrogenic vs. osteogenic differentiation factors). The hBMSCs were harvested, expanded and characterized with respect to their differentiation potential and population distribution. Passage two cells were seeded on scaffolds and cultured for 5 weeks in bioreactors using osteogenic, chondrogenic or control medium. The three media yielded constructs with comparable wet weights and compressive moduli (25 kPa). Chondrogenic medium yielded constructs with higher amounts of DNA (1.5-fold) and glycosaminoglycans (GAG, 4-fold) per unit wet weight (ww) than control medium. In contrast, osteogenic medium yielded constructs with higher dry weight (1.6-fold), alkaline phosphatase (AP) activity (8-fold) and calcium content (100-fold) per unit ww than control medium. Chondrogenic medium yielded constructs that were weakly positive for GAG by contrast-enhanced MRI and alcian blue stain, whereas osteogenic medium yielded constructs that were highly mineralized by μCT and von Kossa stain. Engineered bone constructs were large (8 mm diameter × 2 mm thick disks) and resembled trabecular bone with respect to structure and mineralized tissue volume fraction (12%).