Specific Inhibition Tests Research Articles

New indications of potential rat intestinal α-glucosidase inhibition by Syzygium zeylanicum (L.) and its hypoglycemic effect in mice

Natural α-glucosidase inhibitors (aGIs) have been considered effective agents for type 2 diabetes management. In this study, Syzygium zeylanicum (L.) (SZL), a medicinal plant that grows wild in the Central Highlands of Vietnam, was reported for the first time to have potential anti-diabetic properties. The methanol extract of SZL possessed potent rat intestinal α-glucosidase inhibitory activity with low IC50 and great maximum inhibition values of 109 µg/mL and 100%, respectively. This was higher activity than acarbose, an anti-diabetic drug with IC50 and maximum inhibition values of 540 µg/ml and 80%, respectively. In specific inhibition tests, the herbal extract demonstrated strong inhibition against α-glucosidases from Saccharomyces cerevisiae and Bacillus stearothermophilus with small IC50 values of 0.18 and 0.31 µg/mL, respectively. SZL extract also demonstrated potent inhibition against porcine pancreatic α-amylase with maximum inhibition and IC50 values of 99.2% and 3.7 µg/mL, respectively. SZL displayed high thermal and pH stability, with respective activities of 87% and 100–140% when treated at 100 °C or over a wide pH range of 2–13. The herbal extract was further investigated for its efficacy using ICR mice as the animal model. At a dose of 100 mg/kg BW, SZL significantly reduced blood glucose in mice and no signs of diarrhea were observed. The results from this study suggest that SZL, a potent and natural source of aGIs, may be a good candidate for the treatment of type 2 diabetes.

Pulsed electrical stimulation benefits wound healing by activating skin fibroblasts through the TGFβ1/ERK/NF-κB axis

BackgroundDermal fibroblasts activated by conductive polymer-mediated electrical stimulation (ES) have shown myofibroblast characteristics that favor wound healing. However, the signaling pathway related to this phenotype switch remains unclear, and the in vivo survival of the electrically activated cells has never been studied. MethodsPrimary human skin fibroblasts were exposed to pulsed-ES mediated through polypyrrole (PPy) coated fabrics. The expression of α-smooth muscle actin (α-SMA) and the signaling pathways were investigated by ELISA, Western blot and specific inhibition test, and immunocytochemistry staining as well as qRT-PCR analysis. In vivo implantation was performed in a mouse model to clarify the cell fate or contractile phenotype maintenance following ES stimulation. ResultsWe demonstrated the upregulation of TGFβ1 and phosph-ERK, and the NF-κB nuclear enrichment in the ES-activated cells. The ES-activated fibroblasts retained high level of α-smooth muscle actin expression even after prolonged subculture. Subcutaneous implantation for 15days revealed more human myofibroblasts in the experimental groups. ConclusionsThese findings demonstrate for the first time the involvement of the TGFβ1/ERK/NF-κB signaling pathway in ES-activated fibroblasts. The ES induced phenotype switch proves stable in subculture and in animal, pointing potential application in wound healing. General significanceReveal of how ES activates cells and the implication of ES activated cells in wound healing.

Role of platelet-derived growth factor and transforming growth factor β 1 the in the regulation of metalloproteinase expressions

We investigated the role and influence of platelet derived growth factor (PDGF) and transforming growth factor beta1 (TGF) in the pathologic mechanism at the basis of plaque instability regulating the expression of matrix metalloproteinases (MMPs). Plaques obtained from 70 patients who underwent carotid endarterectomy were classified histologically as stable or unstable. Serum levels of PDGF and TGF were measured pre- and postoperatively. The serum activities of MMP-2 and MMP-9 were also analyzed. Human umbilical artery smooth muscle cells (HUASMCs) were stimulated in vitro with PDGF at various concentrations (20 and 50 ng/mL) and TGF (2 and 5 ng/mL) in a serum-free medium. The release of MMPs in the conditioned medium was assessed by enzyme-linked immunosorbent assay. Release of the MMPs was confirmed by Western blot analysis; their activity and expression were determined by zymography and reverse transcription-polymerase chain reaction. Specific inhibition tests were performed on HUASMCs to evaluate the role of these growth factors. Forty-two (60%) patients had an unstable carotid plaque and 28 (40%) a stable plaque. Preoperatively, patients affected with unstable carotid plaques had higher PDGF and lower TGF plasma levels than patients with stable carotid plaques (P < .001); the levels returned to normal at 1 and 30 days postoperatively, compared with 20 non-operated healthy volunteers. Release, activity, protein level, and expression of MMPs in PDGF-stimulated HUASMCs were greater than in the controls (P < .001), whereas these values in the TGF-stimulated HUASMCs were lower (P < .001). The addition of monoclonal anti-PDGF antibodies decreased the release, activity, protein level, and expression of MMPs, whereas the addition of monoclonal anti-TGF antibodies increased the release, activity, protein level and expression of MMPs (P < .001). TGF seems to be an important stabilizing factor and prevents plaque rupture through the decrease of MMPs.

High binding of immunoglobulin Mκ rheumatoid factor from type II cryoglobulins to cellular fibronectin: A mechanism for induction of in situ immune complex glomerulonephritis?

In our previous experimental work we suggested that the frequent nephritogenicity of type II cryoglobulins could depend on a particular affinity of the immunoglobulin (Ig) Mκ rheumatoid factor (RF) component for mesangial matrix. Since cellular fibronectin (cFN) in the human kidney is mainly represented in glomerular mesangium, we studied the binding capacity of cFN of IgMκ RFs from type II cryoglobulins compared with other different monoclonal and polyclonal IgM and IgM RFs. We purified 13 IgMκ from human IgMκ/IgG cryoglobulins, eight monoclonal IgM from patients with Waldenström's macroglobulinemia, nine polyclonal IgM from normal donors, and eight polyclonal IgM RFs from patients with rheumatoid arthritis. Purified IgM were used at the same concentration in enzyme- linked immunosorbent assay (ELISA) on cFN-coated plates. All the cryoglobulin IgM showed high specific binding to cFN while IgM from Waldenström's macroglobulinemia, normal IgM, and polyclonal IgM RFs had low or absent binding. These data were confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of cFN followed by Western blot analysis with purified IgM. The IgMκ binding to cFN persisted using IgMκ monomers, and was inhibited by cFN but not by plasma FN in a specific inhibition test. Further enzyme-linked immunosorbent assay studies showed that cryoglobulin IgMκ RFs are still able to bind IgG in a dose-dependent manner once linked to solid-phase cFN. The data suggest that the affinity of cryoglobulin IgMκ RFs for immobilized cFN could be involved in the particular high nephritogenicity of type II cryoglobulins and might lead to in situ immune complex formation.

Detection of moulds in foodstuffs and body fluids by immunological determination of the extracellular polysaccharide followed by a specific inhibition test : Nederlanden Min Welzijn EP-325004; 17 March 1993

Supplementation effect of compatible solute ectoine on the ethanol fermentation by Zymomonas mobilis CICC10232 was examined in the presence of high glucose concentration. Addition of ectoine promoted the cell growth as well as volumetric ethanol productivity in the presence of 250 g/l of glucose. At the end of ethanol fermentation, cell dry weight resulted in 1.8 and 1.5 g CDW/l in the presence and absence of 1 mM ectoine, respectively. Volumetric ethanol productivity in the presence of 1 mM ectoine became 1.1 g/l/h, which resulted in 57.1% higher than that in the absence of ectoine, 0.7 g/l/h. In addition, fermentation time was shortened by 24 h when 1 mM ectoine existed in the medium. In the presence of 250 g/l of glucose together with various concentrations of ectoine, relative enzyme activities of glucokinase (GK), glucose-6-phosphate dehydrogenase (G-6-PDH), and alcohol dehydrogenase (ADH) increased by 29.9, 11.6, and 7.7% in the presence of 0.5, 0.5, and 0.25 mM ectoine compared to those without ectoine supplemented, respectively. The promoting function of ectoine on ethanol fermentation may be related to the protection of these enzyme activities under osmotic stress.

Detection of moulds in foodstuffs and body fluids by immunological determination of the extracellular polysaccharide followed by a specific inhibition test : Nederland Staat Min Van Welzijn VS-5149632; 22 September 1992

Detection of moulds in foodstuffs and body fluids by immunological determination of the extracellular polysaccharide followed by a specific inhibition test : Nederland Staat Min Van Welzijn VS-5149632; 22 September 1992

Surface AChE in the chick ciliary ganglion neurons: Ultrastructural localization and possible relations to α-bungarotoxin receptors

The localization of acetylcholinesterase activity in the chick ciliary ganglion was investigated by ultrastructural cytochemistry. Both ganglionic cell populations, i.e. the ciliary and the choroid neurons, showed similar distribution patterns of the enzymic activity in the cytoplasm as well as at the neuronal surface. As indicated by specific inhibition tests, the whole enzymic activity was attributable to specific acetylcholinesterase. While the endocellular activity was mainly localized in the rough endoplasmic reticulum, the surface activity occurred at postsynaptic level and at extrasynaptic areas, where the neuronal membrane comes into contact with the plasma membrane of the satellite cell (boundary neuron-satellite cell). Enzymic activity also uniformly occurred at the surface of preganglionic nerve terminals. The surface localization of specific acetylcholinesterase recalls that recently described for α-bungarotoxin receptors, which suggests that acetylcholinesterase and α-bungarotoxin receptors can be distributed together, not only at postsynaptic level but also in extrasynaptic neuronal areas and at presynaptic level. The possibility that α-bungarotoxin receptors and acetylcholinesterase form a ·receptive’ system not engaged in ganglionic transmission and not exclusively confined to postsynaptic level is discussed in relation to the electrophysiological data existing in literature.

Changes in the inhibition of specific agglutination by plasma due to microvesicles released from human red cells during storage for transfusion.

The progressive appearance of erythrocyte antigenic activity in plasma from donations of human blood taken into acid citrate-dextrose (ACD) and stored at 4 degrees D for transfusion has been studied. It has been shown by specific inhibition tests that A, B, H and P1 activities are associated with membrane-bounded microvesicles which are released from the red cell membrane during the disc-echinocyte-spherocyte shape transformation. Although M group activity appears to be lost from the red cell membrane during storage, significant recovery on the microvesicles is not obtained even though these seem to contain the M and N group intrinsic protein, glycophorin.