Telestroke consultation can accurately diagnose ischemic stroke mimics.

INTRODUCTION: Telestroke (TS) networks are standard in many areas of the US. Despite TS systems having approximately 33% mimic rates, it is unknown if TS can accurately diagnose patients with acute ischemic stroke (AIS) versus stroke mimics. METHODS: We performed a retrospective review of consecutive TS consults to 27 TS sites in six states during 2018. Clinical information and diagnosis were extracted from discharge records and compared to those from the TS consult. Discharge diagnoses were verified and coded into 12 categories. Cases without a clear discharge diagnosis and intracerebral haemorrhage were excluded. We report agreement and a Cohen's kappa between TS and discharge diagnoses for the category of AIS/transient ischemic attack (TIA) versus stroke mimic. RESULTS: We included 404 cases in the analysis (mean age 66 years; 54% women). Of these, 225 had a TS diagnosis of AIS/TIA; 102 (45%) received intravenous tissue plasminogen activator. Our study demonstrated a high diagnostic agreement for AIS/TIA (88%) with a kappa of 0.75 for stroke and mimics. Of the 179 patients diagnosed with a stroke mimic on TS, 27 (15%) were diagnosed with AIS/TA by discharge. TS mimic diagnosis had a positive predictive value (PPV) of 85% and a negative predictive value (NPV) of 90%; TS diagnosis of stroke/TIA had PPV 90%, NPV 85%. DISCUSSION: We found excellent correlation between TS and discharge diagnoses for patients with both stroke and stroke mimics. This suggests that TS systems can accurately assess a wider variety of patients with acute neurologic syndromes other than AIS.

Myostatin stimulates, not inihibits, C2C12 myoblast proliferation.

The immortal C2C12 cell line originates from dystrophic mouse thigh muscle and has been used to study the endocrine control of muscle cell growth, development, and function, including those actions regulated by myostatin. Previous studies suggest that high concentrations of recombinant myostatin generated in bacteria inhibit C2C12 proliferation and differentiation. Recombinant myostatin generated in eukaryotic systems similarly inhibits the proliferation of primary myosatellite cells, but consequently initiates, rather than inhibits, their differentiation and is bioactive at far lower concentrations. Our studies indicate that 2 different sources of recombinant myostatin made in eukaryotes stimulate, not inhibit, C2C12 proliferation. This effect occurred at different cell densities and serum concentrations and in the presence of IGF-I, a potent myoblast mitogen. This stimulatory effect was comparable to that obtained with TGFß1, a related factor that also inhibits primary myosatellite cell proliferation. Attenuating the myostatin/activin (ie, Acvr2b) and TGFß1 receptor signaling pathways with the Alk4/5 and Alk5 inhibitors, SB431542 and SB505142, respectively, similarly attenuated proliferation induced by serum, myostatin or TGFß1 and in a dose-dependent manner. In serum-free medium, both myostatin and TGFß1 stimulated Smad2 phosphorylation, but not that of Smad3, and a Smad3 inhibitor (SIS3) only inhibited proliferation in cells cultured in high serum. Thus, myostatin and TGFß1 stimulate C2C12 proliferation primarily via Smad2. These results together question the physiological relevance of the C2C12 model and previous studies using recombinant myostatin generated in bacteria. They also support the alternative use of primary myosatellite cells and recombinant myostatin generated in eukaryotes.

Genetic manipulation of myoblasts and a novel primary myosatellite cell culture system: comparing and optimizing approaches.

The genetic manipulation of skeletal muscle cells in vitro is notoriously difficult, especially when using undifferentiated muscle cell lines (myoblasts) or primary muscle stem cells (myosatellites). We therefore optimized methods of gene transfer by overexpressing green fluorescent protein (GFP) in mouse C2C12 cells and in a novel system, primary rainbow trout myosatellite cells. A common lipid-based transfection reagent was used (Lipofectamine 2000) along with three different viral vectors: adeno-associated virus serotype 2 (AAV2), baculovirus (BAC) and lentivirus. Maximal transfection efficiencies of 49% were obtained in C2C12 cells after optimizing cell density and reagent : DNA ratio, although the GFP signal rapidly dissipated with proliferation and was not maintained with differentiation. The transduction efficiency of AAV2 was optimized to 65% by extending incubation time and decreasing cell density, although only 30% of cells retained expression after passing. A viral comparison revealed that lentivirus was most efficient at transducing C2C12 myoblasts as 97% of cells were transduced with only 10(6) viral genomes (vg) compared to 54% with 10(8) vg AAV2 and 23% with 10(9) vg BAC. Lentivirus also transduced 90% of primary trout myosatellites compared to 1-10% with AAV2 and BAC. The phosphoglycerate kinase 1 (pgk) promoter was 10-fold more active than the cytomegalovirus immediate-early promoter in C2C12 cells and both were effective in trout myosatellites. Maximal transduction of C2C12 myotubes was achieved by differentiating myoblasts previously transduced with lentivirus and the pgk promoter. Thus, our optimized protocol proved highly effective in diverse muscle cell systems and could therefore help overcome a common technological barrier.