Regenerative Surface Plasmon Resonance (SPR) biosensor: real-time measurement of fibrinogen in undiluted human serum using the competitive adsorption of proteins

Epidemiological studies suggest that elevated plasma fibrinogen levels are associated with an increased risk of cardiovascular disorders. Normal fibrinogen level is in the range of 1.5-4.5mg/mL, depending upon both genetic (intrinsic) and environmental (extrinsic) factors. An increase of 0.25mg/mL from the normal level can often be correlated with a high risk of cardiovascular disease. Thus, it is useful to monitor fibrinogen level in serum of a patient for clinical diagnosis. We report a regenerative biosensor that measures real-time fibrinogen levels in undiluted serum. The biosensor uses Surface Plasmon Resonance (SPR), highly sensitive optical technique. The biosensor does not use bio-receptors (i.e., antibodies, enzymes, DNA, etc.) unlike conventional biosensors, and deploys the nature of competitive adsorption of proteins to achieve selective detection of fibrinogen. We measured fibrinogen-spiked serum samples with a concentration of 1.5-4.5 mg/mL, and repeated six measurement trials to obtain statistical distribution of the measurements using the regeneration method of the sensing surface. The SPR biosensor has a sensitivity of 42 mDeg/(mg/mL) for a fibrinogen concentration in the range of 0.5-2.5 mg/mL, whereas it was hard to correlate the measurements to the spiked-fibrinogen samples of above 2.5 mg/mL.     

Identification of chromatophore membrane protein complexes formed under different nitrogen availability conditions in Rhodospirillum rubrum

The chromatophore membrane of the photosynthetic diazotroph Rhodospirillum rubrum is of vital importance for a number of central processes, including nitrogen fixation. Using a novel amphiphile, we have identified protein complexes present under different nitrogen availability conditions by the use of two-dimensional Blue Native/SDS-PAGE and NSI-LC-LTQ-Orbitrap mass spectrometry. We have identified several membrane protein complexes, including components of the ATP synthase, reaction center, light harvesting, and NADH dehydrogenase complexes. Additionally, we have identified differentially expressed proteins, such as subunits of the succinate dehydrogenase complex and other TCA cycle enzymes that are usually found in the cytosol, thus hinting at a possible association to the membrane in response to nitrogen deficiency. We propose a redox sensing mechanism that can influence the membrane subproteome in response to nitrogen availability.     

Acupuncture enhances the synaptic dopamine availability to improve motor function in a mouse model of Parkinson's disease

Parkinson's disease (PD) is caused by the selective loss of dopaminergic neurons in the substantia nigra (SN) and the depletion of striatal dopamine (DA). Acupuncture, as an alternative therapy for PD, has beneficial effects in both PD patients and PD animal models, although the underlying mechanisms therein remain uncertain. The present study investigated whether acupuncture treatment affected dopamine neurotransmission in a PD mouse model using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). We found that acupuncture treatment at acupoint GB34 improved motor function with accompanying dopaminergic neuron protection against MPTP but did not restore striatal dopamine depletion. Instead, acupuncture treatment increased dopamine release that in turn, may lead to the enhancement of dopamine availability in the synaptic cleft. Moreover, acupuncture treatment mitigated MPTP-induced abnormal postsynaptic changes, suggesting that acupuncture treatment may increase postsynaptic dopamine neurotransmission and facilitate the normalization of basal ganglia activity. These results suggest that the acupuncture-induced enhancement of synaptic dopamine availability may play a critical role in motor function improvement against MPTP.     

Enhancement of differentiation efficiency of hESCs into vascular lineage cells in hypoxia via a paracrine mechanism

Hypoxia is one way of inducing differentiation due to the activation of the key regulatory factor, Hypoxia-inducible factor 1 alpha (HIF-1α). However, the action of HIF-1α on the differentiation of hESCs was unclear until now. To investigate the effect of hypoxia on the differentiation of hESCs, we compared the differentiation efficacy into vascular lineage cells under normoxic and hypoxic conditions. We observed HIF-1α expression and the related expression of pro-angiogenic factors VEGF, bFGF, Ang-1 and PDGF in hEBs cultured under hypoxic conditions. Along with this, differentiation efficacy into vascular lineage cells was improved under hypoxic conditions. When HIF-1α was blocked by echinomycin, both angiogenic factors and the differentiation efficacy were down-regulated, suggesting that the enhancement of differentiation efficacy was caused by intrinsic up-regulation of HIF-1α and these pro-angiogenic factors under hypoxic condition. This response might be primarily regulated by the HIF-1α signal pathway, and hypoxia might be the key to improving the differentiation of hESCs into vascular lineage cells. Therefore, this study demonstrated that microenvironmental changes (i.e., hypoxia) can improve differentiation efficacy of hESCs into a vascular lineage without exogenous factors via cell-intrinsic up-regulation of angiogenic factors. These facts will contribute to the regulation of stem cell fate.     

Replication and pathogenesis of the pandemic (H1N1) 2009 influenza virus in mammalian models

This study aimed to characterize the replication and pathogenic properties of a Korean pandemic (H1N1) 2009 influenza virus isolate in ferrets and mice. Ferrets infected with A/Korea/01/2009 (H1N1) virus showed mild clinical signs. The virus replicated well in lungs and slightly in brains with no replication in any other organs. Severe bronchopneumonia and thickening of alveolar walls were detected in the lungs. Viral antigens were detected in the bronchiolar epithelial cells, in peribronchial glands with severe peribronchitis and in cells present in the alveoli. A/Korea/01/2009 (H1N1) virus-infected mice showed weight loss and pathological lung lesions including perivascular cuffing, interstitial pneumonia and alveolitis. The virus replicated highly in the lungs and slightly in the nasal tissues. Viral antigens were detected in bronchiolar epithelial cells, pneumocytes and interstitial macrophages. However, seasonal H1N1 influenza virus did not replicate in the lungs of ferrets, and viral antigens were not detected. Thus, this Korean pandemic (H1N1) 2009 isolate infected the lungs of ferrets and mice successfully and caused more pathological lesions than did the seasonal influenza virus.