Recent developments in the analysis of avermectin and milbemycin residues in food safety and the environment

A review of the developments on the analysis of residues of avermectins and milbemycins (both macrocyclic lactones) is presented. The macrocyclic lactones (MLs) are an important class of chemicals, which are used worldwide as veterinary drugs and as crop protection agents. As a result, residues of MLs are important from both a food safety and environmental perspective. A review of the developments in ML residues in food was carried out in detail in 2006. As a result, this paper covers recent developments in the area of food analysis, which are mainly multi-residue assays based on liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). A brief coverage of HPLC fluorescence (HPLC-FLD) based methods is included for completeness. The paper will carry out a comprehensive review of ML residues in environmental samples. These additional sections are reflective of the growing number of research papers published on LC-MS/MS and environmental applications in recent years.     

Rhodanine as a scaffold in drug discovery: a critical review of its biological activities and mechanisms of target modulation

INTRODUCTION: Rhodanine-based compounds have been associated with numerous biological activities. After many years of research in drug discovery, they have gained a reputation as being pan assay interference compounds (PAINS) and frequent hitters in screening campaigns. Rhodanine-based compounds are also aggregators that can non-specifically interact with target proteins as well as Michael acceptors and interfere photometrically in biological assays due to their color. AREAS COVERED: The authors review the recently reported biological activities of rhodanine-based compounds. Furthermore, the article provides details of their synthesis and occurrence in compound libraries through high-throughput screening (HTS) and virtual high-throughput screening (VHTS). Additionally, the authors provide the reader with possible mechanisms of non-specific target modulation, analysis of the crystal structures of enzyme-rhodanine complexes and a comparison of rhodanine and thiazolidine-2,4-dione moieties. EXPERT OPINION: The biological activity of compounds possessing a rhodanine moiety should be considered very critically despite the convincing data obtained in biological assays. In addition to the lack of selectivity, unusual structure-activity relationship profiles and safety and specificity problems mean that rhodanines are generally not optimizable.     

Bioactivation of bisphenol A and its analogs (BPF,BPAF, BPZ and DMBPA) in human liver microsomes

Bisphenol A analogs are a class of chemicals known as diphenylmethanes, which contain two benzene rings separated by one central carbon atom, usually with a para-hydroxy group on both benzene rings. Bisphenol A (BPA) can induce an uterotrophic response in immature CD-1 mice and elicits estrogenic responses in many other experimental systems. Besides highlighting endocrine effects, a number of metabolic studies provide strong support for the idea that reactive species of BPA are formed in vitro and in vivo that can form covalent adducts with nucleophilic macromolecules and/or produce oxidative stress. We used a liquid chromatography with a triple quadrupole tandem mass spectrometry (LC–MS/MS) for the detection of metabolites and glutathione conjugates of BPA and its analogs (BPF, BPAF, BPZ and DMBPA) in human liver microsomes (HLM) or with recombinant CYP isozymes in the presence of NADPH and GSH as a trapping agent. We have confirmed that BPA and its structural analogs form hydroxylated metabolites and electrophilic species during bioactivation in HLM and CYP isozymes. These results provided important mechanistic insight into the metabolic fate of BPA structural analogs in vitro.     

Liver regeneration as treatment target for severe alcoholic hepatitis

Severe alcoholic hepatitis (AH) is a distinct entity in the spectrum of alcohol-related liver disease, with limited treatment options and high mortality. Supportive medical care with corticosteroids in selected patients is the only currently available treatment option, often with poor outcomes. Based on the insights into the pathogenetic mechanisms of AH, which are mostly obtained from animal studies, several new treatment options are being explored. Studies have implicated impaired and deranged liver regeneration processes as one of the culprit mechanisms and a potential therapeutic target. Acknowledging evidence for the beneficial effects of granulocyte colony-stimulating factor (G-CSF) on liver regeneration and immunomodulation in animal models, several human studies investigated its role in the treatment of advanced alcohol-related liver disease and AH. Contrary to the previously published studies suggesting benefits of G-CSF in the outcomes of patients with severe AH, these effects were not confirmed by a recently published multicenter randomized trial, suggesting that other options should rather be pursued. Stem cell transplantation represents another option for improving liver regeneration, but evidence for its efficacy in patients with severe AH and advanced alcohol-related liver disease is still very scarce and unconvincing, with established lack of efficacy in patients with compensated cirrhosis. In this review, we summarize the current knowledge on the pathogenesis and experimental therapies targeting liver regeneration. The lack of high-quality studies and evidence is a major obstacle in further treatment development. New insights into the pathogenesis of not only liver injury, but also liver regeneration processes are mandatory for the development of new treatment options. A reliable experimental model of the pathogenesis of AH and processes involved in liver recovery is still missing, and data obtained from animal studies are essential for future research.     

Results of extracorporeal life support implementation in routine clinical practice: single center experience

Aim

To describe our experience in the clinical application of extracorporeal life support (ECLS) and analyze whether ECLS leads to acceptable clinical outcomes in patients with cardiac failure.

Methods

Data from clinical database of University Hospital Center Zagreb, Croatia, on 75 patients undergoing ECLS support from 2009 to 2014 due to cardiac failure were retrospectively analyzed. Outcomes were defined as procedural and clinical outcomes. ECLS as a primary procedure and ECLS as a postcardiotomy procedure due to inability to wean from cardiopulmonary bypass were analyzed.

Results

ECLS was used in 75 adult patients, and in 24 (32%) of those procedural success was noted. ECLS was implemented as a primary procedure in 36 patients and as a postcardiotomy procedure in 39 patients. Nine out of 39 (23.08%) patients had postcardiotomy ECLS after heart transplantation. Bleeding complications occurred in 30 (40%) patients, both in primary (11/36 patients) and postcardiotomy group (19/39 patients). ECLS was established by peripheral approach in 46 patients and by central cannulation in 27 patients. In 2 patients, combined cannulation was performed, with an inflow cannula placed into the right atrium and an outflow cannula placed into the femoral artery. Eleven patients treated with peripheral approach had ischemic complications.

Conclusion

ECLS is a useful tool in the treatment of patients with refractory cardiac failure and its results are encouraging in patients who otherwise have an unfavorable prognosis. The idea of extracorporeal life support (ECLS) became a reality with the introduction of the heart-lung machine by Gibbon in 1954 (1). However, only in 1971 the first successful extracorporeal membrane oxygenation treatment was described (2). Since then continuous technological improvements have led to the growing interest in this type of treatment (3).ECLS may significantly improve the level of patient care in patients with acute and chronic heart failure. It is an advanced form of treatment and the patient management is carried out by a multidisciplinary team of cardiac surgeons, anesthesiologists, and cardiologists.There are two main groups of indications for ECLS: those not related and those related to cardiac surgery. Primary ECLS procedures are not related to cardiac surgery but to acute cardiorespiratory failure arising from underlying cardiac disease. Postcardiotomy ECLS procedures may be considered as a secondary procedure and are directly related to cardiac surgery procedures. These procedures are indicated after cardiac surgery procedures when patients cannot be weaned from cardiopulmonary bypass or when there is low cardiac output syndrome in the early postoperative phase. Postcardiotomy cardiogenic shock occurs in up to 6% of cardiac operations (4-6), with only 25% of those patients surviving to hospital discharge (4). Therefore, postcardiotomy cardiogenic shock is one of the most difficult and resource-consuming conditions, as it is associated with particularly high mortality rates. Since the risk profiles of patients scheduled for cardiac surgery procedures are continuously worsening, one may expect an increase in the number of patients requiring ECLS peri-operatively. Although these patients have only 25% of survival to hospital discharge (4), one should be aware that they would have nearly 100% mortality if they were not placed on ECLS. Although early ECLS results for postcardiotomy cardiogenic shock were found to be poor (5,7), they have been improved by continuous technological advances (5,8-10). Primary ECLS procedures may also play a significant role in cardiac surgery patients. In general, ECLS restores body perfusion and allows different treatment modalities. This may help optimize a patient’s clinical condition while waiting for a heart transplant. If a patient is not considered a suitable candidate for a heart transplant, ECLS may provide a bridge to long-term mechanical circulatory support. However, if ECLS is intended to bridge a patient to recovery (for instance in patients with acute myocarditis), then ECLS support may be considered as a treatment per se.ECLS may be used as either; 1) bridge to recovery, 2) bridge to transplant, 3) bridge to decision, or 4) bridge to intermediate or long term support. “Bridging concept” is important because a lack of exit strategy (eg, reason for bridging) may actually suggest a possible contraindication for ECLS.ECLS may play a significant role in patients with acute cardiogenic shock prior to scheduled cardiac surgery procedures such as intermediate to long term mechanical circulatory support, heart transplant, or other cardiosurgical procedures depending on the preexisting condition.Preoperative patient optimization using ECLS improves the outcomes of the level 1 Interagency Registry for Mechanically Assisted Circulatory Support (INTERMACS) patients receiving a permanent ventricular assist device (11). This “bridge-to-bridge” concept consisted of preoperative stabilization of level 1 INTERMACS patients using ECLS a few days prior to ventricular assist device implantation. ECLS significantly improved renal, hepatic, and pulmonary functions (11).In addition to this, preoperative ECLS support may significantly improve outcomes in patients presenting with acute myocardial infarction (AMI) complicated with ventricular septal defect (VSD) and cardiogenic shock (12). Preoperative ECLS provided hemodynamic support, ensured end-organ perfusion, helped the myocardium to recover and allow scar tissue to be formed by reducing sheer forces, thus leading to more favorable outcomes (12).For both primary and postcardiotomy indications, our team generally prefers combined support to the heart and lungs (ECLS) rather than isolated mechanical circulatory support to the failing heart. ECLS can be implanted bedside, providing support to both the heart and the lungs simultaneously. Nowadays ECLS is available in many centers that do not perform ventricular assist device implantation. In such centers, patients should be preoperatively stabilized and transferred on support to tertiary care centers for further treatment. To facilitate this process, it would be necessary to establish an ECLS network with ECLS centers cooperating with tertiary centers that perform long term mechanical circulatory support, heart transplant, as well as complex surgical corrections. In this article, we describe our experience in the clinical application of extracorporeal life support (ECLS) and aim to analyze whether ECLS leads to acceptable clinical outcomes in patients with cardiac failure.     

SPECTRAL STUDIES ON TWO GENETIC FORMS OF THE HUMAN SERUM PROTEINASE INHIBITOR,ALPHA-1-ANTITRYPSIN*

Alpha-1-antitrypsin, the major inhibitor of proteolytic enzymes in human serum, was isolated from normal individuals (protease inhibitor type MM) and from those with an inherited deficiency (protease inhibitor type ZZ) of circulatory protein. The two proteins were compared by circular dichroism spectroscopy, and by fluorescence quenching experiments using anionic (I^-), and neutral (acrylamide) probes. Both proteins share a similar secondary structure, i.e. ?45–50%α-helix and 15–20%β-structure. Evidence was accumulated to show that the micro-environment in the vicinity of the three tryptophanyl residues is altered in Z form as compared to the M form as shown by (a) the absence of the positive dichroic band in the region 290–300nm of the circular dichroism spectra, (b) a > 50% increase in quantum yield in the tryptophanyl fluorescence emission spectra, (c) an increased accessibility of tryptophan to quenching by iodide, and (d) acrylamide quenching experiments which indicate that all tryptophanyl residues in the Z protein are quenched equally or that quenching is dominated by a single residue, while in the M protein, heterogeneous quenching occurs. The potential significance of these findings in terms of alpha-1-antitrypsin deficiency state are discussed.     

Adjusted blood requirement index as indicator of failure to control acute variceal bleeding

Aim

To estimate the clinical value of adjusted blood requirement index (ABRI) in relation to other criteria for failure of variceal bleeding control proposed at Baveno consensus workshops and to evaluate ABRI as an early predictor of occurrence of other Baveno criteria and identification of possible predictors of unfavorable ABRI.

Methods

We retrospectively analyzed the data on 60 patients admitted to the hospital due to acute variceal bleeding. Number of treatment failures according to Baveno II-III and Baveno IV definitions and criteria was compared. We tested the ABRI’s predictability of other Baveno IV and Baveno II-III criteria. Logistic regression analysis was performed to ascertain independent variables that predict ABRI≥0.75.

Results

Failure to control variceal bleeding occurred in 40 of 60 patients according to Baveno II-III criteria, and in 35 of 60 patients according to Baveno IV criteria. Excluding the criterion of “transfusion of 2 units of blood or more (over and above the previous transfusions)” and ABRI criterion, failure to control variceal bleeding was observed in 17 and 14 of 60 patients, respectively. Congruence of ABRI with other criteria was present in about two-thirds of the cases. ABRI≥0.75 was associated with increased risk of positive other Baveno criteria, particularly modified Baveno II-III (odds ratio [OR] 4.10; 95% confidence interval [CI], 1.11-15.05) and Baveno IV without ABRI (OR 4.37; 95% CI, 1.04-18.28). Independent predictors of ABRI≥0.75 identified in logistic regression analysis were male sex (P<0.001) and higher hematocrit values (P=0.004).

Conclusion

We found low congruence between ABRI and other Baveno criteria and the incidence of treatment failure in our study was higher than the previously reported frequencies of early rebleeding. It seems that criteria related to the quantity of blood transfusions are not reliable indicators of treatment failure.Prevalence of esophageal varices in patients with liver cirrhosis is high, as by the time of diagnosis, they are present in up to 40% of compensated patients and up to 60% of those who present with ascites (1-3). Approximately 30% of patients experience an episode of variceal hemorrhage within 2 years of the diagnosis of varices (4,5). Acute bleeding from varices in a patient with portal hypertension often poses a life-threatening medical emergency with a mortality that is, in spite of the recent progress, still around 20% at 6 weeks (6,7). Bleeding-associated mortality is highest in the first 5 days after the first episode of variceal bleeding and returns to baseline after 3-4 months (5,8).Several definitions and criteria to evaluate failure to control variceal bleeding and failure to prevent variceal rebleeding, as well as prognostic indicators of rebleeding, were developed previously at three Baveno Consensus Workshops (9-13). With application in clinical trials, it has been found that they have a limited clinical value (14). Therefore, new definitions and criteria have been recently proposed at Baveno IV Consensus Workshop (14). Adjusted blood requirement index (ABRI) has been suggested as an independent criterion to define the failure to control bleeding, but it has not been validated yet.The aims of this study were to evaluate the clinical significance and consistency of ABRI in relation to other criteria of failure to control variceal bleeding proposed at Baveno Consensus Workshops (9-14), to determine if ABRI could be used as an early predictor of occurrence of other Baveno criteria, and to identify predictors of unfavorable ABRI.