Design of Novel Saposin-like Bacteriocins Using a Hybrid Approach

A multitude of approaches will be required to respond to the threat posed by the emergence and spread of antibiotic resistant pathogens. Bacteriocins have gained increasing attention as a possible alternative to antibiotics, as such peptide antimicrobials have mechanisms of action different from antibiotics and are therefore equally potent against antibiotic resistant bacteria as their susceptible counterparts. A group of bacteriocins known as saposin-like bacteriocins is believed to act directly on the bacterial membrane. Based on seven saposin-like leaderless bacteriocins, we have constructed a library of hybrid peptides containing all combinations of the N- and C-terminal halves of the native bacteriocins. All hybrid peptides were synthesized using in vitro protein expression and assayed for antimicrobial activity towards several pathogens. Of the 42 hybrid peptides, antimicrobial activity was confirmed for 11 novel hybrid peptides. Furthermore, several of the hybrid peptides exhibited altered antimicrobial spectra and apparent increase in potency compared to the peptides from which they were derived. The most promising hybrid, termed ISP26, was then obtained synthetically and shown to inhibit most of the Gram-positive species tested, including opportunistic pathogens and food spoilage bacteria. Additionally, ISP26 was shown to inhibit Acinetobacter, a species of Gram-negative bacteria frequently isolated from nosocomial infections. The activity of the hybrid library provides valuable insights into the design and screening of new active bacteriocins.

Evaluation of the interrelated effects of slaughtering, drying, and defatting methods on the composition and properties of black soldier fly (Hermetia illucens) larvae fat

The interrelated effect of different slaughtering, drying and defatting methods of black soldier fly larvae (BSFL) on the lipid composition and properties of the fat was studied. Blanching and freezing were compared as slaughtering methods, oven or freeze-drying as drying methods, and mechanical pressing or supercritical fluid extraction (SFE) as defatting methods. The different modes of slaughtering, drying, and defatting, along with both binary and ternary interactions caused significant effects on processes yields, lipid composition, moisture content and thermal properties. Thus, considering the defatting degree and the yield in total valued products (defatted meal plus fat), the combination of blanching, freeze-drying plus mechanical pressing was the worst option (51.2% and 87.5%, respectively). In contrast, the other combinations demonstrated better and comparable efficiency, although SFE is preferable for defatting (83.2% and 96.9%, respectively). The content of major fatty acids (lauric, palmitic and myristic acids) was significantly affected by the BSFL treatments, although with unsignificant impact on the total saturated fatty acids content. To preserve the integrity of the fat, the combination of blanching and oven-drying was preferred, as non-thermal methods of slaughtering and drying caused intense lipolysis, releasing free fatty acids (FFA) in the range of 18.6-23.5%. To achieve the lowest moisture content in the fats (≤0.1%), oven-drying with mechanical pressing were desired, regardless of the slaughtering method; while values > 1% were reached for freezing, freeze-drying and SFE. Both differences in FFA and moisture contents caused different thermal behaviors in the samples. Specially, the melting temperature was lower for samples with higher FFA and moisture contents, with a notable difference when freezing, freeze-drying and SFE were combined (14.5 °C vs 30.6 °C, as the mean value for the rest of samples). The different modes of processing did not affect the minor lipid compounds. Therefore, the modes employed for slaughtering, drying, and defatting of BSFL determine, either individually or in combination, the process yields, composition, and properties of the fat.

Short chain fatty acids reduce the respiratory burst of human neutrophils in response to cystic fibrosis isolates of Staphylococcus aureus

Short chain fatty acids (SCFA) are produced by anaerobic bacteria. The most common SCFAs are acetate, propionate and butyrate. SCFAs have been implicated in several inflammatory diseases including cystic fibrosis (CF) where they are present in the airways at millimolar concentrations. Staphylococcus aureus is one of the main respiratory pathogens in CF. Polymorphonuclear neutrophil granulocytes (PMN) represent the most important immune defense the host uses against S. aureus. However, the reason why PMNs are unable to clear S. aureus in CF remains largely unclear. We hypothesized that SCFAs impair effector functions of PMNs in response to S. aureus. To test this, human PMNs were exposed to CF clinical isolates of S. aureus in vitro in the presence or absence of SCFAs and effector functions of PMNs were assessed. Our data show that SCFAs do not affect the viability of PMNs and do not stimulate the release of neutrophil extracellular traps (NET) from human PMNs. Production of reactive oxygen species (ROS), another important antimicrobial function of PMNs, on the other hand, was significantly inhibited by SCFAs in response to the bacterium. SCFAs did not compromise the ability of PMNs to kill CF isolates of S. aureus in vitro. Overall, our results provide new knowledge into the interactions between SCFAs and the immune system, and indicate that SCFAs produced by anaerobic bacteria in the CF lung could interfere with reactive oxidant production of PMNs in response to S. aureus, one of the prominent respiratory pathogens in this disease.

Novel lectin-based chimeric antigen receptors target Gb3-positive tumour cells

The link between cancer and aberrant glycosylation has recently become evident. Glycans and their altered forms, known as tumour-associated carbohydrate antigens (TACAs), are diverse, complex and difficult to target therapeutically. Lectins are naturally occurring glycan-binding proteins  that offer a unique opportunity to recognise TACAs. T cells expressing chimeric antigen receptors (CARs) have proven to be a successful immunotherapy against leukaemias, but so far have shown limited success in solid tumours. We developed a panel of lectin-CARs that recognise the glycosphingolipid globotriaosylceramide (Gb3), which is overexpressed in various cancers, such as Burkitt's lymphoma, colorectal, breast and pancreatic. We have selected the following lectins: Shiga toxin's B-subunit from Shigella dysenteriae, LecA from Pseudomonas aeruginosa, and the engineered lectin Mitsuba from Mytilus galloprovincialis as antigen-binding domains and fused them to a well-known second-generation CAR. The Gb3-binding lectin-CARs have demonstrated target-specific cytotoxicity against Burkitt's lymphoma-derived cell lines as well as solid tumour cells from colorectal and triple-negative breast cancer. Our findings reveal the big potential of lectin-based CARs as therapeutical applications to target Gb3 and other TACAs expressed in haematological malignancies and solid tumours.

Treatment for Moral Injury: Impact of Killing in War

Purpose of Review

Veterans who kill in war are at risk of developing negative mental health problems including moral injury, PTSD, spiritual distress, and impairments in functioning. Impact of Killing (IOK) is a novel, cognitive-behaviorally based treatment designed to address the symptoms associated with killing that focuses on self-forgiveness and moral repair through cultivation of self-compassion and perspective-taking exercises, such as letter writing, and active participation in values-driven behavior.

Recent Findings

In a pilot trial assessing IOK, participants demonstrated a reduction in multiple mental health symptoms and improvement in quality-of-life measures, and they reported IOK was acceptable and feasible. Furthermore, trauma therapists have reported that moral injury is relevant to their clinical work, expressed a desire for additional training on the impact of killing, and identified barriers that make addressing killing in clinical settings challenging. Data are currently being collected in a national multi-site trial to examine the efficacy of IOK, compared to a control condition.

Summary

IOK fills a critical treatment gap by directly addressing the guilt, shame, self-sabotaging behaviors, functional difficulties, impaired self-forgiveness, and moral/spiritual distress directly associated with killing in war. Typically provided following some initial trauma-processing treatment, IOK can be integrated in existing systems of trauma care, creating a pathway for a stepped model of treatment for moral injury.

The inviolateness of life and equal protection: a defense of the dead-donor rule

There are increasing calls to reject the dead-donor rule and permit organ donation euthanasia in organ transplantation. I argue that the fundamental problem with this proposal is that it would bestow more worth on the organs than on the donor who possesses them. What is at stake is the basis of human equality, which, I argue, should be based on an ineliminable dignity that each of us has in virtue of having a rational nature. To allow mortal harvesting would be to make our worth contingent upon variable quality-of-life judgments that can be based only on properties that come in degrees. Thus, rejecting the dead-donor rule comes at the expense of egalitarian principles with respect to the value each individual human life has in relation to the protections against killing.

Examining Neutrophil-Candida auris Interactions with Human Neutrophils Ex Vivo

Neutrophils play a key role in controlling invasive fungal infections. These phagocytes engage and kill fungal pathogens through a variety of effector mechanisms. Here, we describe how to isolate human neutrophils for ex vivo study of neutrophil-Candida auris interactions. We detail assays to measure fungal killing, phagocytosis, and reactive oxygen species production.

Wireless 'under the skull' epidural EEG and behavior in piglets during nitrous oxide or carbon dioxide gas euthanasia

Consciousness is central to animal welfare concerns. Its assessment is most often conducted based on behavior, with a poor understanding of the correspondence between behavior and the neurobiological processes that underlie the subjective experience of consciousness. Recording of brain electrical activity using electrodes placed under the skull improves EEG recording by minimizing artifacts from muscular or cardiac activities, and it can now be combined with wireless recording in free-moving animals. This experiment investigated the correspondence between wireless 'under the skull' epidural EEG and the behavior of 18 five-week-old female piglets undergoing nitrous oxide (N₂O) or carbon dioxide (CO₂) gradual fill gas euthanasia at 25% replacement rate per minute of the chamber volume. Piglets exposed to CO₂ had a peak in EEG total power ('Ptot') during the flailing stage, whereas piglets exposed to N₂O had a higher EEG 95% spectral edge frequency ('F95') during their initial explorative behavior phase and a drop in EEG median frequency ('F50') after loss of posture. Loss of posture without righting attempt, as the last behavioral state observed during euthanasia, preceded the onset of transitional EEG on average by 0.9 and 3.1 min (for CO₂ and N₂O treatments, respectively), and the onset of isoelectric EEG by 4.5 and 6.2 min (for CO₂ and N₂O treatments, respectively). Paddling movements occurred shortly before and during transitional EEG but never during isoelectric EEG, whereas gasps persisted after the EEG had become isoelectric. The dynamics of EEG spectral changes were complex to interpret in relation to the degree of consciousness, but isoelectric EEG as an unequivocal indicator of unconsciousness appeared several minutes after loss of posture with no righting attempt. This leaves a window of uncertainty in regards to the potential for consciousness after loss of posture during gradual fill gas euthanasia in piglets.

A comprehensive three-dimensional assay to assess neutrophil defense against bacteria

Neutrophil antibacterial capacity is measured in animal models and in vitro as an important indicator of neutrophil function. To be able to extrapolate their conclusions, in vitro experiments should mimic the in vivo situation. In vivo, antibacterial capacity depends on multiple steps of bacterial sensing, priming, chemotaxis, phagocytosis and intracellular killing. Therefore, we developed a simply executed assay that involves multiple steps in one assay. The neutrophils were incorporated into a three-dimensional matrix of fibrin fibers, in which they could freely migrate. The fibrin matrix provided a more physiological representation of tissue structure than a shaken suspension and extended ex vivo survival of neutrophils. Staphylococci endogenously producing GFP (Green Fluorescent Protein) provided a real-time quantification of the bacterial load without the need for lysing the fibrin matrix or counting of colony forming units on agar plates. The delay in bacterial outgrowth serves as a measure for the relative antibacterial capacity of the neutrophils. Additionally, neutrophil capacity could easily be measured high-throughput in a 96-wells format. In this new assay we study neutrophil behavior in a physiologically relevant setting and explore many functions of the neutrophil in a single test. The functional capacity of neutrophils from different in vitro treatments or different donors can directly be compared.

How 'The Urge to Kill' Feels: Articulations of Emic 'Appetitive Aggression' Experiences Among Former Forcefully Recruited Children and Youth in the Acholi Region of Northern Uganda

Based on 10 months of fieldwork in the Acholi region of northern Uganda among youth and adults who were forcefully recruited into the Lord's Resistance Army (LRA) during the war, this article provides qualitative details to research on 'appetitive aggression.' Through two case-stories the article unfolds first person articulations of how 'appetitive aggression' is experienced as 'the urge to kill' and how it relates to the emic Acholi spiritual concept of 'cen'; a local Luo expression used to describe places and human beings possessed by evil spirits. The analysis illuminates what the individual and social implications of 'the urge to kill' and 'cen' entail for two Acholi men; first in a militia and then in a civil post-war context. The analysis then relates these findings to soldier experiences across cultures and time periods. While our analysis supports the findings in 'appetitive aggression' studies that appetitive aggression serves as a resilient protective factor against developing post-traumatic stress disorder (PTSD), this study documents that once the former forcefully recruited return to civilian life, 'appetitive aggression' and 'the urge to kill' precipitate individual and at times lethal social and moral complications in a fragile post-war community. Thus, the article argues that appetitive aggression and the emic perceptions and experiences of it among the local population are essential to consider in studies, processes and programs targeting demobilization, rehabilitation, reconciliation and re-integration.

How (not) to think of the 'dead-donor' rule

Although much has been written on the dead-donor rule (DDR) in the last twenty-five years, scant attention has been paid to how it should be formulated, what its rationale is, and why it was accepted. The DDR can be formulated in terms of either a Don't Kill rule or a Death Requirement, the former being historically rooted in absolutist ethics and the latter in a prudential policy aimed at securing trust in the transplant enterprise. I contend that the moral core of the rule is the Don't Kill rule, not the Death Requirement. This, I show, is how the DDR was understood by the transplanters of the 1960s, who sought to conform their practices to their ethics-unlike today's critics of the DDR, who rethink their ethics in a question-begging fashion to accommodate their practices. A better discussion of the ethics of killing is needed to move the debate forward.

Size matters - how the immune system deals with fungal hyphae

Fungal hyphae constitute a special challenge for the immune system, since they are too large to be phagocytosed. This review summarizes our current knowledge on those immune cells that are able to attack and eliminate hyphae and we discuss the different means that are employed by these cells in order to kill hyphae.

The ethics of and the appropriate legislation concerning killing people and letting them die: a response to Merkel

With regard to ethics and legislation, what is the significant difference between a doctor terminating the life-supporting treatment of a patient in the course of his job and a greedy relative of the patient doing the same thing to inherit his wealth? Merkel offers an interesting and inventive answer to this question in terms of the improper violation of personal boundaries. However, despite Merkel's claim to the contrary, his answer does not directly address the question of the relevant ethical similarities and differences between killing and letting die in general. Furthermore, it does not provide the basis a plausible rationale for legislation concerning killing and letting die. The questions of whether letting someone die is ethically the same as killing someone and whether it should be treated the same way by the criminal law are not the same as or tantamount to the question of whether or not it involves the transgression of another person's boundaries.

Refinement of intraperitoneal injection of sodium pentobarbital for euthanasia in laboratory rats (Rattus norvegicus)

Background

The Canadian Council on Animal Care and American Veterinary Medical Association classify intraperitoneal (IP) pentobarbital as an acceptable euthanasia method in rats. However, national guidelines do not exist for a recommended dose or volume and IP euthanasia has been described as unreliable, with misinjections leading to variable success in ensuring a timely death. The aims of this study were to assess and improve efficacy and consistency of IP euthanasia.

In a randomized, blinded study, 51 adult female Sprague-Dawley rats (170–495 g) received one of four treatments: low-dose low-volume (LL) IP pentobarbital (n = 13, 200 mg/kg pentobarbital), low-dose high-volume (LH) IP pentobarbital (n = 14, 200 mg/kg diluted 1:3 with phosphate buffered saline), high-dose high-volume (HH, n = 14, 800 mg/kg pentobarbital), or saline. Times to loss of righting reflex (LORR) and cessation of heartbeat (CHB) were recorded. To identify misinjections, necropsy examinations were performed on all rats. Video recordings of LL and HH groups were analyzed for pain-associated behaviors. Between-group comparisons were performed with 1-way ANOVA and Games-Howell post hoc tests. Variability in CHB was assessed by calculating the coefficient of variation (CV).

Results

The fastest euthanasia method (CHB) was HH (283.7 ± 38.0 s), compared with LL (485.8 ± 140.7 s, p = 0.002) and LH (347.7 ± 72.0 s, p = 0.039). Values for CV were: HH, 13.4%; LH, 20.7%; LL, 29.0%. LORR time was longest in LL (139.5 ± 29.6 s), compared with HH (111.6 ± 19.7 s, p = 0.046) and LH (104.2 ± 19.3 s, p = 0.01). Misinjections occurred in 17.0% (7/41) of euthanasia attempts. Pain-associated behavior incidence ranged from 36% (4/11, LL) to 46% (5/11, HH).

Conclusions

These data illustrate refinement of the IP pentobarbital euthanasia technique. Both dose and volume contribute to speed of death, with a dose of 800 mg/kg (HH) being the most effective method. An increase in volume alone does not significantly reduce variability. The proportion of misinjections was similar to that of previous studies.

Assessment of Post-Vaccination Phagocytic Activation Using Candida albicans Killing Assays

Candida albicans is an important opportunistic fungal pathogen. It is now the fourth leading cause of nosocomial bloodstream infections and a great threat to the immuncompromised patients attributed to the disseminated candidiasis with the mortality up to 40%. Phagocytic cells are the first line of defense against Candida infections. Antibodies induced by vaccination can effectively enhance the capacities of phagocytosis and killing of neutrophils and macrophages. In this chapter, flow cytometric analysis (FACS) and killing assay by plate culture methods are introduced to evaluate the phagocytosis and killing of strains of Candida albicans opsonized with immune serum obtained from mice vaccinated with yeast and recombinant enolase.

Smoke and mirrors: unanswered questions and misleading statements obscure the truth about organ sources in China

This response refutes the claim made in a recent article that organs for transplantation in China will no longer be sourced from executed prisoners. We identify ongoing ethical problems due to the lack of transparent data on current numbers of transplants in China; implausible and conflicting claims about voluntary donations; and obfuscation about who counts as a voluntary donor. The big unanswered question in Chinese transplant ethics is the source of organs, and until there is an open and independently audited system in China, legitimate concerns remain about organ harvesting from prisoners of conscience.

Syntaxin 8 is required for efficient lytic granule trafficking in cytotoxic T lymphocytes

Cytotoxic T lymphocytes (CTL) eliminate pathogen-infected and cancerous cells mainly by polarized secretion of lytic granules (LG, containing cytotoxic molecules like perforin and granzymes) at the immunological synapse (IS). Members of the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) family are involved in trafficking (generation, transport and fusion) of vesicles at the IS. Syntaxin 8 (Stx8) is expressed in LG and colocalizes with the T cell receptor (TCR) upon IS formation. Here, we report the significance of Stx8 for human CTL cytotoxicity. We found that Stx8 mostly localized in late, recycling endosomal and lysosomal compartments with little expression in early endosomal compartments. Down-regulation of Stx8 by siRNA resulted in reduced cytotoxicity. We found that following perforin release of the pre-existing pool upon target cell contact, Stx8 down-regulated CTL regenerate perforin pools less efficiently and thus release less perforin compared to control CTL. CD107a degranulation, real-time and end-point population cytotoxicity assays, and high resolution microscopy support our conclusion that Stx8 is required for proper and timely sorting and trafficking of cytotoxic molecules to functional LG through the endosomal pathway in human CTL.

Broadening the future of value account of the wrongness of killing

On Don Marquis's future of value account of the wrongness of killing, 'what makes it wrong to kill those individuals we all believe it is wrong to kill, is that killing them deprives them of their future of value'. Marquis has recently argued for a narrow interpretation of his future of value account of the wrongness of killing and against the broad interpretation that I had put forward in response to Carson Strong. In this article I argue that the narrow view is problematic because it violates some basic principles of equality and because it allows for some of the very killing that Marquis sets out to condemn; further, I argue that the chief reason why Marquis chooses the narrow view over the broad view-namely that the broad view would take the killing of some non-human animals to be also wrong-should rather be considered a welcome upshot of the broad view.

Kant on euthanasia and the duty to die: clearing the air

Thanks to recent scholarship, Kant is no longer seen as the dogmatic opponent of suicide that he appears to be at first glance. However, some interpreters have recently argued for a Kantian view of the morality of suicide with surprising, even radical, implications. More specifically, they have argued that Kantianism (1) requires that those with dementia or other rationality-eroding conditions end their lives before their condition results in their loss of identity as moral agents and (2) requires subjecting the fully demented or those confronting future dementia to non-voluntary euthanasia. Properly understood, Kant's ethics have neither of these implications (1) wrongly assumes that rational agents' duty of self-preservation entails a duty of self-destruction when they become non-rational, (2) further neglects Kant's distinction between duties to self and duties to others and wrongly assumes that duties can be owed to rational agents only during the time of their existence.

'Total disability' and the wrongness of killing

Walter Sinnott-Armstrong and Franklin G Miller recently argued that the wrongness of killing is best explained by the harm that comes to the victim, and that 'total disability' best explains the nature of this harm. Hence, killing patients who are already totally disabled is not wrong. I maintain that their notion of total disability is ambiguous and that they beg the question with respect to whether there are abilities left over that remain relevant for the goods of personhood and human worth. If these goods remain, then something more is lost in death than in 'total disability,' and their explanation of what makes killing wrong comes up short. But if total disability is equivalent with death, then their argument is an interesting one.

Does withdrawing life-sustaining treatment cause death or allow the patient to die?

This article discusses recent arguments of Franklin Miller and Robert Truog about withdrawal of life-sustaining treatment and causation. The authors argue that traditional medical ethics, and the law, are mistaken to take the view that withdrawal merely allows the patient to die, rather than causing the patient's death, describing such a view as 'patently false'. They argue that the law's continued position to the contrary stems from a moral bias, resulting in the moral and legal fiction that withdrawal does not cause death but lets the patient die. In so arguing, Miller and Truog join a long line of academic criticism of the law that extends back to the seminal decision of Airedale NHS Trust v Bland [1993] AC 789 (HL) and beyond. In this article, I take issue with these claims. I argue that there are reasonable grounds upon which traditional medical ethics and the law can regard withdrawal of life-sustaining treatment as allowing the patient to die rather than causing death, and so the authors' claims that such a view is patently false cannot be sustained. I then tease out the implications of my conclusions for the authors' claim that there is not such a great distinction between withdrawal of life-sustaining treatment, euthanasia, and assisted dying. I conclude by discussing some possible objections to my own view.