R86Q, a mutation in BmAChE3 yielding a Rhipicephalus microplus organophosphate-insensitive acetylcholinesterase

Mutations were identified in the cDNA sequence encoding the acetylcholinesterase BmAChE3 in strains of Rhipicephalus (Boophilus) microplus (Canestrini) resistant or susceptible to organophosphate (OP) acaricide. The mutation that occurred most frequently in the OP-resistant San Román strain resulted in a substitution of glutamine (Q) for arginine (R) at position 86 in BmAChE3 (position 66 in mature BmAChE). Clones containing the mutant and wild-type cDNA sequences were expressed in the baculovirus system. Enzyme kinetics of recombinant BmAChE3 containing or lacking the R86Q mutation demonstrated that the R86Q mutation increased substrate affinity and conferred insensitivity to paraoxon inhibition. This is the first demonstration of a mutation in a gene encoding an ixodid acetylcholinesterase resulting in OP insensitivity. A restriction fragment length polymorphism assay was developed and used to diagnose the frequency of the R86Q mutation in BmAChE3 genomic DNA from seven laboratory-colonized strains. Use of the R86Q diagnostic assay detected an increased frequency of the R86Q mutation in OP-resistant tick strains compared with that of OP-susceptible strains; however, the R86Q mutation was also present in OP-susceptible strains at unexpectedly high frequency. Because the R86Q mutation generates an OP-resistant enzyme in vitro and it is present at an elevated frequency in laboratory strains selected for OP resistance, we conclude that the data are consistent with a potential role for BmAChE3 in development of OP resistance; however, because the R86Q mutation has a high frequency in susceptible strains, the R86Q mutation alone is insufficient to generate the OP-resistant phenotype at the organismal level. There are likely to be additional mutations in BmAChE3, mutations in additional acetylcholinesterase genes, or additional resistance mechanisms (e.g., oxidative metabolism) that contribute to expression of the OP-resistant phenotype.     

Coronavirus disease 2019: Implications of emerging infections for transplantation

The recent identification of an outbreak of 2019‐ novel Coronavirus is currently evolving, and the impact on transplantation is unknown. However, it is imperative that we anticipate the potential impact on the transplant community in order to avert severe consequences of this infection on both the transplant community and contacts of transplant patients.     

Combination of pancreas volume and HbA1c level predicts islet yield in patients undergoing total pancreatectomy and islet autotransplantation

Islet yield is an important predictor of acceptable glucose control after total pancreatectomy with islet autotransplantation (TP-IAT). We assessed if pancreas volume calculated with preoperative MRI could assess islet yield and postoperative outcomes. We reviewed dynamic MRI studies from 154 adult TP-IAT patients (2009-2016), and associations between calculated volumes and digest islet equivalents (IEQs) were tested. In multivariate regression analysis, pancreas volume (P < .001) and preoperative HbA1c levels (P = .009) were independently associated with digest IEQs. The IEQ prediction formula was calculated according to each preoperative HbA1c level, (a) pancreas volume × 5800 for HbA1c ≥ 6.5, (b) pancreas volume × 10 000 for HbA1c ≥5.7/<6.5 and (iii) pancreas volume × 11 400 for HbA1c < 5.7. The formula was internally validated with 28 TP-IAT patients between 2017 and 2018 (r² = .657 and r² = .710 when restricted to 24 patients without prior pancreatectomy). An estimated IEQs/Body Weight (kg) ≥3700 predicted HbA1c ≤6.5 and insulin independence at 1 year after TP-IAT with 77% and 88% sensitivity and 55% and 43% specificity, respectively. The combination of pancreas volume and preoperative HbA1c levels may be useful to estimate islet yield. Estimated IEQs were reasonably sensitive to predict acceptable glucose control at 1 year.     

A multicenter study of total pancreatectomy with islet autotransplantation (TPIAT): POST (Prospective Observational Study of TPIAT)

Background/objectives

Total pancreatectomy with islet autotransplantation (TPIAT) is considered for managing chronic pancreatitis in selected patients when medical and endoscopic interventions have not provided adequate relief from debilitating pain. Although more centers are performing TPIAT, we lack large, multi-center studies to guide decisions about selecting candidates for and timing of TPIAT.

Interleukin 2 induction of lymphokine-activated killer (LAK) activity in the peripheral blood and bone marrow of acute leukemia patients. I. Feasibility of LAK generation in adult patients with active disease and in remission

The feasibility of in vitro interleukin 2 (IL-2) activation and expansion of mononuclear cells (MNCs) derived from adult patients with acute myelogenous leukemia (ANLL) was studied. Patients' natural killer (NK) and lymphokine-activated killer (LAK) cell activity was compared with that of normal donors in terms of: (a) cytolytic activity (four- hour 51Cr release assay) against an NK-sensitive target (K562), NK- resistant targets (Raji/Daudi), and fresh/cryopreserved autologous and allogeneic leukemic blasts; (b) proliferation and expansion in culture with 1,000 U/mL recombinant IL 2 (rIL 2); and (c) the cell surface phenotype of the cultured cells. In 21 of 24 patients with active disease (AP) MNCs derived from the peripheral blood (PBL) or bone marrow (BM) could be cultured and expanded in the presence of rIL 2. These cultures initially contained between 30% and 50% blasts, and during 2 to 4 weeks of culture destruction of blasts and enrichment of up to 60% in cells with the morphology of large granular lymphocytes (LGLs) was observed. Expansion in culture varied between two- and 100- fold. MNCs from all patients in remission (RP) could be activated by rIL 2 and expanded up to 30-fold after 1 to 3 weeks in culture. NK activity of fresh PBLs from AP was significantly lower than in normal controls, whereas NK activity of RP was within the normal range. High levels of postactivation NK and LAK activity on K562/Raji/Daudi and on fresh/cryopreserved leukemic blasts was generated in approximately 50% of cases of AP and in most RP. Cell surface phenotype studies showed that cultured cells derived from ANLL patients were significantly enriched (up to 40%) in NKH-1 (Leu 19) positive cells, with RP LAK cells also expressing a high proportion of CD16 positive cells (up to 40%). This study has shown that it is feasible to activate and significantly expand killer cells derived from active disease and remission ANLL patients during 1 to 3 weeks culture with IL 2 with good maintenance of cytolytic activity. Both initial NK activity and LAK generation was optimal in remission patients. Based on data from this study, a clinical protocol has been developed for treatment of early relapse ANLL patients with LAK cells cultured for 1 to 3 weeks and systemic IL 2.     

An inhibitory monoclonal antibody to factor X that blocks prothrombin activation but not prothrombinase enzyme assembly

A monoclonal antibody (designated alpha BFX-2b) prepared against bovine factor X inhibited factor X activity in human, bovine, porcine, rabbit, and canine plasma. In assays using purified prothrombinase components, factor Xa, factor Va, phospholipid vesicles, and calcium ion with the fluorescent active site thrombin inhibitor dansylarginyl-N-(3-ethyl-1,5- pentanediyl)amide, the antibody inhibited the conversion of prothrombin to thrombin. Antibody alpha BFX-2b also blocked prothrombinase cleavage of the macromolecular substrates prethrombin 1 and prethrombin 2 but did not inhibit factor Xa hydrolysis of the synthetic substrate benzoyl- Ile-Glu-Gly-Arg-p-nitroanilide. The antibody also prevented the inactivation of factor Xa by antithrombin III but did not prevent the inactivation by soybean trypsin inhibitor. Antibody alpha BFX-2b bound factor Xa with a stoichiometry of 1:1 and an apparent dissociation constant of 9.0 x 10(-11) mol/L as estimated from its inhibition of prothrombinase activity. Antibody alpha BFX-2b did not prevent binding of factor Xa to factor Va-phospholipid as measured by using fluorescence polarization or high-pressure liquid gel chromatography with the fluorescent Factor Xa analogue dansyl-glutamyl-glycyl-arginyl- Xa. Immunoblotting of factor X following electrophoresis on sodium dodecyl sulphate-polyacrylamide gels and transfer to nitrocellulose indicated that the antigenic determinant recognized by antibody alpha BFX-2b was found on the heavy chain of factors X and Xa. From these observations it can be concluded that antibody alpha BFX-2b recognizes a highly conserved epitope on the factor X heavy chain that is remote from the topographic sites required for prothrombinase complex assembly and substrate hydrolysis but may be located at or near a portion of the macromolecular substrate binding site.     

Cystic fibrosis: An update for clinicians. Part 2: Hepatobiliary and pancreatic manifestations

This paper, the second in the series, will build on the first and explore the importance of liver and pancreatic manifestations of cystic fibrosis (CF) and the effect on morbidity and mortality of this multifaceted genetic condition. It will also further develop the critical role of the gastroenterologist as part of the multidisciplinary group of clinicians and allied health staff in the effective management of patients with CF.     

Potential immunomodulatory activity of phenylphosphonothioates

In the course of immunotoxicological studies of several organophosphorous compounds, it was noted that some phenylphosphonothioates enhanced the activation of rat splenocytes by concanavalin A. In the present study some of these compounds were compared to the well-characterized immunomodulatory thiol, 2-mercaptoethanol (2-ME). Two of the compounds are able to substitute for 2-ME and allow near maximal growth of a strictly 2-ME-dependent lymphocyte cell line (CTLL-2). These compounds exhibit essentially additive effects with 2-ME on CTLL-2 cells and rat splenocytes. In agreement with previous results with 2-ME, the phosphonothioates have essentially no effect on interleukin-2 production in mitogen-stimulated splenocyte cultures. One phosphonothioate, as well as its possible thiol hydrolysis product, supports cell survival and enhanced cystine incorporation by CTLL-2 cells. However, 2-ME was more effective in stimulation of enhanced generation of extracellular thiols than were the other agents. These results suggest very similar modes of action for phosphonothionates and 2-ME. Finally, a phosphonothioate selected for low neurotoxic potential was examined and found to effectively support lymphocyte growth in vitro and to exhibit relatively low acute toxicity in mice.     

头皮糠疹与巯氧吡啶锌

头皮糠疹是常见病是多发病,临床表现为头皮红斑和脱屑,提示皮损部位表皮结构和功能异常,头皮角质层代谢紊乱,最近对头皮糠疹病因和病理的研究证实马拉色菌,皮脂分泌和个体敏感性是形成上述皮损的3个关键因素,硫氧吡啶锌（PTZ或ZPT）可以有效地杀灭马拉色菌,PTZ的颗粒大小和形状对其在头皮的生物利用度有明显的影响。此外,PTZ的抗菌效果有赖于其分子结构的完整性,在外用制剂中加入附加的游离锌,可以有效防止PTZ解离,从而提高其疗效。