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Extracts from white birch have been reported to possess antimicrobial properties, but no study has linked the chemical composition of bark extract with antimicrobial activity. This study aimed to identify white birch (Betula papyrifera Marshall) bark extracts with antimicrobial activity and elucidate its composition. In order to obtain the highest extraction yield, bark residues >3 mm were retained for extraction. A total of 10 extraction solvents were used to determine the extraction yield of each of them. Methanol and ethanol solvents extracted a greater proportion of molecules. When tested on eight microorganism species, the water extract proved to have the best antimicrobial potential followed by the methanol extract. The water extract inhibited all microorganisms at low concentration with minimal inhibitory concentration between 0.83 and 1.67 mg/ml. Using ultraperformance liquid chromatography coupled to a time-of-flight quadrupole mass spectrometer, several molecules that have already been studied for their antimicrobial properties were identified in water and methanol extracts. Catechol was identified as one of the dominant components in white birch bark water extract, and its antimicrobial activity has already been demonstrated, suggesting that catechol could be one of the main components contributing to the antimicrobial activity of this extract. Thus, extractives from forestry wastes have potential for new applications to valorize these residues., (© 2019 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.)

The continual emergence of pathogen resistance is a recurring challenge and pushes for the development of antimicrobial compounds. Here, we investigated compounds from quaking aspen trees ( Populus tremuloides ) as potential antimicrobial agents. Several extractions using different solvents were realized, and corresponding antimicrobial activity was tested against eight microorganisms. Results revealed that polar extraction solvents including water, ethanol and methanol gave the best extraction yields (>15.07%). Minimal inhibition concentration (MIC) and minimal bactericidal/fungicidal concentration (MBC/MFC) demonstrated that water extracts had the best antimicrobial activity by a weak to moderate inhibition of growth of all eight tested microorganisms in addition to having a bactericidal effect on three of them. The quaking aspen methanol extract also displayed antimicrobial activity but to a lower level than the water extract. Ultra-performance liquid chromatography quadrupole time-of flight mass spectrometry (UPLC-QTOF-MS) analysis led to the identification of 92 compounds, mainly polyphenols in both extracts, with 22 molecules previously known for their antimicrobial properties. According to the relative abundance, 4-hydroxybenzaldehyde (5.44% in methanol extract) and kaempferol (5.03% in water extract) were the most abundant antimicrobial compounds. Among antimicrobial molecules identified, nine were from the flavonoid family. The results of our study demonstrate the interest of using quaking aspen as source of antimicrobial compounds.

Objective: We show that significant interlaboratory and intralaboratory variations exist in Lyme disease proficiency testing., Design: Six case-defined Lyme serum samples and three serum samples from individuals with no history of Lyme disease were randomized in four shipments and distributed to 45 participating laboratories., Results: Interlaboratory and intralaboratory performances were highly variable. Approximately 4% to 21% of laboratories failed to identify correctly positive serum samples with titers of 512 or more using polyvalent serum or immunoglobulin G conjugates. With lower levels of anti-Borrelia burgdorferi antibody in the serum sample, approximately 55% of participating laboratories did not identify a case-defined serum. There was also a striking inability of many laboratories to reproduce their results on split samples from the same individual. In addition, 2% to 7% of laboratories identified serum samples from individuals with no known exposure to B burgdorferi as positive using polyvalent serum. The false positivity rate increased to 27% with the use of immunoglobulin G conjugate., Conclusions: Our results indicate that there is an urgent need for standardization of current testing methodologies. Until a national commitment is made, serological testing for Lyme disease will be of questionable value for the diagnosis of the disease.

The localization and identity of the human platelet 24 kDa cyclic AMP (cAMP)-dependent phosphoprotein, previously reported to regulate Ca2+ transport, was investigated. It was found to be located on plasma membranes after isolation of these membranes from microsomes. Thus cAMP-dependent regulation of Ca2+ transport was associated with the plasma membrane fraction. Time course studies showed that the catalytic subunit of cAMP-dependent protein kinase (c-sub) induced a maximal 2-fold stimulation of Ca2+ uptake by the plasma membrane vesicles. This stimulation was dose-dependent up to 15 micrograms of c-sub/ml. The increase in Ca2+ uptake also depended upon the outside Ca2+ concentration, and was maximal at 1 microM. As regards the identity of the phosphoprotein, it was clearly distinct from the beta-subunit of glycoprotein Ib, as after electrophoresis under reduced conditions it appeared as a 24 kDa protein, but under non-reduced conditions it appeared as a 22 kDa and not as a 170 kDa protein. Nevertheless, glycoprotein Ib was certainly present, because it was detected with two polyclonal antibodies raised against its two subunits. Furthermore, the 24 kDa phosphoprotein was also present in membranes isolated from platelets obtained from patients with Bernard Soulier Syndrome; these membranes contain no glycoprotein Ib.

The addition of inositol 1,4,5-trisphosphate (IP3) to a 45Ca-preloaded human platelet membrane fraction (dense tubular system) induced a transient release of Ca2+. When the vesicle fraction was loaded with 45Ca2+ to isotopic equilibrium in the presence of the catalytic subunit of the cAMP-dependent protein kinase, the level of Ca2+ uptake was increased and the subsequent IP3-induced Ca2+ release was enhanced. The stimulation was observed regardless of the IP3 concentration used, and was maximal with an enzyme concentration of 5 micrograms/ml. The addition of the protein kinase inhibitor prevented the stimulatory effect of the catalytic subunit on IP3-induced calcium release, and also abolished the calcium release detected in the absence of added enzyme. It is concluded that a cAMP-dependent protein phosphorylation may be involved in the regulation of the IP3-induced Ca2+ release in human platelets.

The effect of inositol 1,4,5 trisphosphate (IP3) has been investigated on the cAMP-induced phosphorylation of the 23-Kd protein involved in platelet calcium fluxes by isolated membrane vesicles. The studies were conducted using the catalytic subunit of the cAMP-dependent protein kinase (C. Sub.). A dose-dependent stimulation of the 23 Kd protein phosphorylation induced by C. Sub. was initiated by IP3 with a half-maximal effect of 0.5 microM. The maximal effect was observed after 1-2 min. The effect was detected in the absence of Ca2+ and in the presence of phosphatase inhibitors. These results can suggest that the 23 Kd is an associated protein to the IP3 receptor in human platelets.

The effect of cAMP (which involved a 23 kDa protein phosphorylation) has been studied on the Ca2+ uptake and Ca2+ release from a human platelet membrane vesicle fraction. It was tested in the presence of the catalytic subunit of the cAMP-dependent protein kinase (C Sub). The addition of C Sub increased the steady state level of the Ca2+ uptake into the membrane vesicles. The effect was enhanced when tested in the absence of Ca2+ precipitating agent. The response was proportional to the dose of C Sub. Moreover, the effect varied with the Ca2+ concentration. The effect of C Sub has been tested on the inositol 1,4,5-trisphosphate (IP3)-induced Ca2+ release. A phosphorylated state of the 23 kDa protein appeared to be necessary. Indeed, a phosphorylation inhibition prevented the IP3 effect and the addition of C Sub increased the percentage of released Ca2+ (without modification of the time course). However, the C Sub dose-dependent response was not linear. The effect of cAMP on the two functions (Ca2+ uptake and Ca2+ release) appears to be different. Therefore, these results led us to suggest a more complex role of cAMP in the regulation of platelet Ca2+ concentration.