An enzyme-centric approach for constructing an amperometric l-malate biosensor with a long and programmable linear range

l-Malate is a key flavor enhancer and acidulant in the food and beverage industry, particularly winemaking. Enzyme-based amperometric biosensors offer convenience for monitoring its concentration. However, only a small number of off-the-shelf malate-oxidizing enzymes have been used in previous devices. These typically have linear ranges poorly suited for the l-malate concentrations found in fruit processing and winemaking, making it necessary to use precisely diluted samples. Here, we describe a pipeline of database-mining, gene synthesis, recombinant expression, and spectrophotometric assays to characterize previously untested enzymes for their suitability in biosensors. The pipeline yielded a bespoke biocatalyst-the Ascaris suum malic enzyme carrying mutation R181Q [AsME(R181Q)]. Our first prototype with AsME(R181Q) had an ultra-wide linear range of 50-200 mM l-malate, corresponding to concentrations found in undiluted fruit juices (including grape). Changing the dication from Mg2+ to Mn2+ increased sensitivity five-fold and adding citrate (100 mM) increased it another six-fold, albeit decreasing the linear range to 1-10 mM. To our knowledge, this is the first time an l-malate biosensor with a tuneable combination of sensitivity and linear range has been described. The sensor response was also tested in the presence of various molecules abundant in juices and wines, with ascorbate shown to be a potent interferent. Interference was mitigated by the addition of ascorbate oxidase, allowing for differential measurements on an undiluted, untreated wine sample that corresponded well with commercial l-malate testing kits. Overall, this work demonstrates the power of an enzyme-centric approach for designing electrochemical biosensors with improved operational parameters and novel functionality.

Diffuse Pigmented Villonodular Synovitis as a Rare Cause of Graft Failure Following Anterior Cruciate Ligament Reconstruction

This case report describes a 42-year-old woman who was diagnosed with pigmented villonodular synovitis (PVNS) in the knee. The patient had received a bone-patella tendon-bone autograft reconstruction of her anterior cruciate ligament (ACL) 22 years prior to her diagnosis of PVNS. After a traumatic event that tore her ACL graft, she underwent a second surgery to repair the initial reconstruction. However, her pain and joint instability remained unresolved. When radiolucent lesions in her tibia and femur were identified through a radiographic image, the patient was referred to the authors' orthopedic oncology clinic. Additional imaging, including magnetic resonance imaging, revealed PVNS, and she was scheduled for debridement and a complete synovectomy of the knee. After surgery, the patient's pain decreased dramatically. She continues to maintain an active lifestyle despite a relatively minor decrease in range of motion. In this case, PVNS proved to be an unlikely complication after ACL reconstruction. The patient remains at risk for the development of degenerative arthritis. [Orthopedics. 2018; 41(1):e142-e144.].

Potent and Selective Inhibitors of Histone Deacetylase-3 Containing Chiral Oxazoline Capping Groups and a N-(2-Aminophenyl)-benzamide Binding Unit

A novel series of potent chiral inhibitors of histone deacetylase (HDAC) is described that contains an oxazoline capping group and a N-(2-aminophenyl)-benzamide unit. Among several new inhibitors of this type exhibiting Class I selectivity and potent inhibition of HDAC3-NCoR2, in vitro assays for the inhibition of HDAC1, HDAC2, and HDAC3-NCoR2 by N-(2-aminophenyl)-benzamide 15k gave respective IC50 values of 80, 110, and 6 nM. Weak inhibition of all other HDAC isoforms (HDAC4, 5, 6, 7, and 9: IC50 > 100 000 nM; HDAC8: IC50 = 25 000 nM; HDAC10: IC50 > 4000 nM; HDAC11: IC50 > 2000 nM) confirmed the Class I selectivity of 15k. 2-Aminoimidazolinyl, 2-thioimidazolinyl, and 2-aminooxazolinyl units were shown to be effective replacements for the pyrimidine ring present in many other 2-(aminophenyl)-benzamides previously reported, but the 2-aminooxazolinyl unit was the most potent in inhibiting HDAC3-NCoR2. Many of the new HDAC inhibitors showed higher solubilities and lower binding to human serum albumin than that of Mocetinostat. Increases in histone H3K9 acetylation in the human cell lines U937 and PC-3 was observed for all three oxazolinyl inhibitors evaluated; those HDAC inhibitors also lowered cyclin E expression in U937 cells but not in PC-3 cells, indicating underlying differences in the mechanisms of action of the inhibitors on those two cell lines.

Novel chiral skeletons for drug discovery: antibacterial tetramic acids

Modification of the ring nucleus of tetramic acids derived from serine gives chiral heterocyclic libraries that exhibit antibacterial activity, and correlation with various physicochemical parameters indicates that chiral tetramic acids may provide a potentially valuable non-aromatic skeleton for fragment-based drug discovery.

Decay of pure quantum turbulence in superfluid 3He-B

We describe measurements of the decay of pure superfluid turbulence in superfluid 3He-B, in the low temperature regime where the normal fluid density is negligible. We follow the decay of the turbulence generated by a vibrating grid as detected by vibrating wire resonators. Despite the absence of any classical normal fluid dissipation processes, the decay is consistent with turbulence having the classical Kolmogorov energy spectrum and is remarkably similar to that measured in superfluid 4He at relatively high temperatures. Further, our results strongly suggest that the decay is governed by the superfluid circulation quantum rather than kinematic viscosity.

Emission of discrete vortex rings by a vibrating grid in superfluid 3He-B: a precursor to quantum turbulence

We report a transition in the vorticity generated by a grid moving in the B phase of superfluid 3He at T<<T(c). The evolution of the vorticity after arresting the grid shows a dramatic change in the decay rate at a critical grid velocity. We believe this to reflect a sharp transition from ballistic vortex-ring production at low grid velocities to quantum turbulence at higher velocities and that independent isolated vortex rings provide the precursors to the developed turbulence. Furthermore we believe that this may be a feature of all quantum turbulence arising from repetitive mechanical agitation.

Vimentin Antibodies: A Non-HLA Antibody as a Potential Risk Factor in Renal Transplantation

Chronic allograft rejection is the major problem encountered in solid organ transplantation and is the end point of several complex processes. A number of recent studies show both alloimmune and autoimmune responses may have roles to play. The importance of HLA antibodies in transplantation is well documented, but despite the introduction of very sensitive HLA screening assays, antibody-mediated allograft rejection still occurs without detectable HLA antibodies. The target for antibody-mediated allograft rejection in these circumstances remains elusive, perhaps due to the variety of potential targets presented on endothelial cells. Recent studies identifying C4d and immunoglobulin deposits in patients undergoing late allograft loss provide evidence that chronic rejection involves humoral as well as cellular components. Several endothelial cell antigens that might be important in chronic rejection have been suggested, including MHC class I chain-related genes; Lewis; and the intermediate filament protein, vimentin. Vimentin is an ideal candidate antigen for antibody-mediated rejection as it is found in endothelial cells and is exposed to the immune system following surgery or by chronic allograft rejection due to endothelial cell breakdown, where the development of antibodies may cause further damage. We have developed a flow cytometric assay for the detection of antibodies to vimentin and have investigated whether HLA or vimentin antibodies are present in renal transplant recipients undergoing chronic rejection.

Pentanuclear homoleptic M(5)L(6) (M = Mn(II), Co(II), Zn(II)) complexes formed by strict self-assembly

A series of trigonal bipyramidal pentanuclear complexes involving the alkoxo-diazine ligands poap and p3oap, containing the M(5)[mu-O](6) core is described, which form by a strict self-assembly process. [Co(5)(poap-H)(6)](ClO(4))(4).3H(2)O (1), [Mn(5)(poap-H)(6)](ClO(4))(4).3.5CH(3)OH.H(2)O (2), [Mn(5)(p3oap-H)(6)](ClO(4))(4).CH(3)CH(2)OH.3H(2)O (3), and [Zn(5)(poap-H)(6)](ClO(4))(4).2.5H(2)O (4) are homoleptic pentanuclear complexes, where there is an exact match between the coordination requirements of the five metal ions in the cluster, and the available coordination pockets in the polytopic ligand. [Zn(4)(poap)(poap-H)(3)(H(2)O)(4)] (NO(3))(5).1.5H(2)O (5) is a square [2 x 2] grid with a Zn(4)[mu-O](4) core, and appears to result from the presence of NO(3), which is thought to be a competing ligand in the self-assembly. X-ray structures are reported for 1, 4, and 5. 1 crystallized in the monoclinic system, space group P2(1)/n with a = 13.385(1) A, b = 25.797(2) A, c = 28.513(3) A, beta = 98.704(2) degrees, and Z = 4. 4 crystallized in the triclinic system, space group P1 with a = 13.0897(9) A, b = 18.889(1) A, c = 20.506(2) A, alpha = 87.116(1) degrees, beta = 74.280(2) degrees, gamma = 75.809(2) degrees, and Z = 2. 5 crystallized in the monoclinic system, space group P2(1)/n with a = 14.8222(7) A, b = 21.408(1) A, c = 21.6197(9) A, beta = 90.698(1) degrees, and Z = 4. Compounds 1-3 exhibit intramolecular antiferromagnetic coupling.

Absorptive apical amiloride-sensitive Na+ conductance in human endometrial epithelium

1. Human endometrial epithelial cells cultured on porous tissue culture supports formed tight, polarized epithelial monolayers with features characteristic of tight epithelia. Endometrial epithelial layers generated significant transepithelial electrical resistance (750 Omega cm2) and potential difference (15.3 mV), with an inward short-circuit current (Isc; 20.5 microA cm-2). 2. The Isc was linearly proportional to the external Na+ concentration and was abolished in the absence of Na+. The Isc was sensitive to apical amiloride. Net 22Na+ flux was in the absorptive apical to basolateral direction and fully accounted for the inward Isc. In addition, apical to basolateral and net 22Na+ transport were reduced in the presence of amiloride. 3. The Isc was also sensitive to addition of ouabain and Ba2+ to the basal solution, consistent with a role for basolateral Na+-K+-ATPase and K+ channels in generation of the current. 4. These data demonstrate that human endometrial epithelial cells in primary culture produce tight, functional monolayers on permeable supports. We provide the first evidence that human endometrial epithelial cells have an inward Isc accounted for by an amiloride-sensitive Na+ conductance. The Na+-absorptive function of the endometrium may provide an appropriate environment for sperm function and embryo growth.

Oestrogen and progesterone do not regulate the expression of retinoic acid receptors and retinoid 'X' receptors in human endometrial stromal cells in vitro

Elucidation of the gene structure for retinoic acid receptor-beta (RAR-beta) has suggested a potential role for oestrogen in regulating the expression of RAR-beta. We have previously shown that all three RAR types are expressed in human endometrial stromal cells in vitro and that RAR-beta expression is induced in response to retinoic acid. The aim of this study was to ask whether oestradiol and progesterone could play a part in regulating the expression of RARs in human endometrial stromal cells and to establish the patterns of expression of a related group of nuclear retinoid receptors, retinoid 'X' receptors (RXRs) and their potential for regulation by steroid hormones. The RAR expression patterns of endometrial stromal cells, grown in steroid-free medium, did not change in response to the presence of steroid hormones. Furthermore, the retinoic acid-mediated induction of RAR-beta was not affected by oestradiol or progesterone, and was dependent on the continued presence of retinoic acid. Of the three RXR types, only RXR-alpha was detectably expressed in stromal cells in vitro and the expression of RXR-alpha did not change in response to steroid hormones or retinoic acid. These data indicate that oestradiol and progesterone are not important in the regulation of RAR and RXR expression in human endometrial stromal cells.

Ion transport by human endometrial epithelia in vitro

Human glandular endometrial epithelial cells were cultured on porous tissue culture inserts to form tight, confluent layers. These layers generated time-dependent modifications in the ionic composition of both apical and basolateral solutions. Increases in sodium and chloride concentrations in the basolateral fluid were accompanied by reciprocal decreases in the concentrations of these ions in the apical fluid. The potassium concentration was increased in the apical, while decreased in the basolateral, solution. The total calcium concentration was slightly elevated in the apical, as compared with the basolateral fluid, while there were no alterations in pH. The endometrial layers demonstrated a significant transepithelial potential difference, and when this value was substituted in the Nernst equation a prediction of the passive distribution of ions across the cells was possible, indicating that none of the ions were in equilibrium. Addition of the sodium channel blocker amiloride to the medium bathing the cell layers reduced the modifications in ionic composition of apical and basolateral solutions. The data are consistent with other data indicating an amiloride-sensitive sodium-absorptive function for the endometrial epithelium. The ability of these primary cultures of endometrial epithelial cells to reduce the sodium while increasing the potassium concentration of the apical fluid is qualitatively in agreement with the low sodium and high potassium concentrations reported for human uterine fluid. The data suggest a role for the endometrial epithelium in generating and maintaining the distinctive ionic composition of the intra-uterine environment.

Bombesin and gastrin-releasing peptide stimulate electrogenic ion transport in cultured human endometrial epithelial cell layers

Electrogenic ion transport across human endometrial epithelial cells grown as polarized monolayers on permeable supports was measured as an inward short-circuit current (Isc; 16.2 +/- 1.1 microA/cm2). Bombesin (10(-7) M) and human gastrin-releasing peptide (GRP; 10(-7) M) caused transient enhancement of this Isc. These effects were largely restricted to the basolateral surface of the cells; responses to apical peptide were modest in comparison with those to basolateral peptide. GRP and other bombesin-related peptides may have a role in regulation of endometrial epithelial ion transport in vivo and thereby influence the intra-uterine environment.

Bradykinin stimulation of electrogenic ion transport in epithelial layers of cultured human endometrium

Primary cultures of glandular endometrial epithelial cells grown on permeable supports formed monolayers with a high transepithelial electrical resistance [1096 +/- 83 omega.cm2 (n = 34)] and displayed electrogenic ion transport as demonstrated by an inward short circuit current (Isc; 20 +/- 2 microA/cm2). Bradykinin, 10(-8)-10(-6) M, added to either the basolateral or apical solutions enhanced the inward ISC. The concentration-response curves for bradykinin were bell-shaped in nature. The ISC response was more sensitive to apical addition of bradykinin and the maximum response was also greater with apical bradykinin. The increases in ISC were accompanied by two- to three-fold increases in transepithelial conductance. Apical addition of amiloride, 10(-4) M, reduced the unstimulated ISC by 80%. In the presence of amiloride, the response to both apical and basolateral bradykinin was reduced by > 50% in 8 out of 18 layers, and the mean response was reduced by approximately 25%. The data are consistent with a physiological role for bradykinin in the control of the intrauterine electrolyte environment, mediated in part by enhanced Na+ absorption.

The expression of retinoic acid receptors in cultured human endometrial stromal cells and effects of retinoic acid

Patterns of expression of retinoic acid receptors (RAR) in cultures of human endometrial stromal cells are described. Transcripts for all three classes of RAR were expressed in these cells but RAR-beta was expressed at a low level by comparison with RAR-alpha and RAR-gamma. The abundance of RAR-beta transcripts was elevated by treating the cells with retinoic acid, but there was no effect on the level of expression of RAR-alpha and RAR-gamma. The induction of RAR-beta by retinoic acid was detectable within 4 h and at low concentrations of retinoic acid (10(-10) M). Adenosine 3':5'-cyclic monophosphate (cAMP) analogues and forskolin, an adenylate cyclase activator, had no effect on the retinoic acid-mediated induction of RAR-beta, contrary to recent observations on embryonal carcinoma cells. However, the phosphodiesterase inhibitor, 3-isobutyl-1-methyl-xanthine (IBMX), forskolin and 8-bromo-cAMP depressed basal levels of RAR-beta expression. These data suggest that endometrial stromal cells may be a target tissue of retinoic acid in vivo, and imply a role for retinoic acid in the cyclical differentiation of human endometrium.

Characterization of human purified epithelial and stromal cells from endometrium and endometriosis in tissue culture

OBJECTIVE

To initiate in vitro cultures of separate stromal and epithelial elements from endometriotic tissue and to compare the characteristics of these cells with those of cultured endometrial cells.

DESIGN

The study involved testing the viability of a culture system for endometriotic tissue and examination of the phenotype of the cells.

SETTING

Fresh tissue samples were collected from the operating theater and transferred to the tissue culture laboratory.

PATIENTS, PARTICIPANTS

Twenty patients undergoing laparotomy for endometriosis and patients undergoing surgery for benign conditions were recruited.

INTERVENTIONS

Endometrium and endometriotic tissue were separated, cultured in vitro, and labeled by indirect immunofluorescence with monoclonal antibodies against cytoskeletal components and epithelial mucins.

MAIN OUTCOME MEASURES

Endometriotic cells have been maintained in vitro and found to resemble endometrial cells closely.

RESULTS

With respect to the staining patterns for cytokeratins 18 and 19, vimentin, and three different epithelial mucins, cultured cells from both endometrium and endometriotic tissue had similar properties. Cytokeratins were located in epithelial cells, and vimentin was expressed in both stromal and epithelial cells. The antimucin antibodies all gave distinct patterns of intracellular staining of epithelial cells.

CONCLUSIONS

Our results indicate a close similarity between cultured stromal and epithelial cells from endometrium and endometriotic deposits. Culture of these cell populations will permit study of their properties and interactions and may provide some insight into the cause of endometriosis.

Antigen presenting capacity of murine decidual tissue in vivo

Antigen presenting cells (APC) within murine decidual tissue in vivo have been shown to process the soluble antigen ovalbumin after intravenous administration and to present it in a form recognizable by immune T lymphocytes. In vivo antigen pulsed decidual APC stimulated T cell proliferation as efficiently as splenic APC and in an MHC restricted manner. In addition, anti-class II antibody plus complement treatment significantly reduced decidual antigen presenting capacity in vitro. These findings show that class II positive cells within the decidua can present antigen effectively in vivo and may therefore serve as APC for the presentation of fetal antigens to the maternal immune system during pregnancy.

Differential expression of class II major histocompatibility complex and Thy 1.2 antigens on mouse decidua

A differential expression of class II major histocompatibility complex (MHC) and Thy 1.2 antigens was detected on two morphologically distinct cell populations in short-term cultures of murine decidual tissue. Stromal type decidual cells expressed Thy 1.2, albeit transiently, and consistently lacked class II antigens. By contrast decidual macrophages expressed class II antigens and lacked Thy 1.2 antigens. Stromal type decidual cells, after culture in the presence of indomethacin, displayed no evidence of prostaglandin-mediated modulation of class II expression. These findings suggest that class II positive decidual macrophages are responsible for the antigen-presenting capacity of decidua.

The role of prostaglandins in the immunosuppressive effects of supernatants from adherent cells of murine decidual tissue

Supernatants from short-term cultures of murine decidual tissue (DS) were assessed for their regulatory effects on T cell lymphoproliferation and cytotoxic T lymphocyte (CTL) activity. DS non-specifically suppressed antigen- and mitogen-induced lymphoproliferation, spontaneous thymocyte proliferation, the mixed lymphocyte reaction (MLR) and CTL generation, but had no effect on CTL lytic activity. The immunosuppressive activity was lost after dialysis (14 kDa cut off). Supernatants from indomethacin-treated decidual tissue cultures (indomethacin-DS) lacked suppressive activity in the MLR, mitogen and thymocyte proliferation assays. Indomethacin-DS also showed markedly reduced or no suppressive effects on CTL generation. These findings suggest that prostaglandin production by the decidual component of the placenta could play a role in materno-fetal cellular interactions by regulating T cell lymphoproliferative responses and CTL generation.

Detection of macrophages and the characterization of Fc receptor-bearing cells in the mouse decidua, placenta and yolk sac using the macrophage-specific monoclonal antibody F4/80

A mouse macrophage-specific rat monoclonal antibody, F4/80, has been used to detect directly macrophages in short term cultures of mouse decidua, fetal placenta and yolk sac and to investigate the identity of Fc receptor (FcR) bearing cells in these tissues. We find that a significant proportion of FcR positive cells in decidual, placental and yolk sac tissues are macrophages as defined by the expression of the macrophage marker, F4/80 antigen. Macrophages may act as immunocompetent cells near to the maternal-fetal interface and play a significant role in the mechanism of the transfer of passive immunity from mother to fetus across the mouse yolk sac.