The Dynamics of SARS-CoV-2 Infectivity with Changes in Aerosol Microenvironment

Understanding the factors that influence the airborne survival of viruses such as SARSCoV2 in aerosols is important for identifying routes of transmission and the value of various mitigation strategies for preventing transmission. We present measurements of the stability of SARSCoV2 in aerosol droplets (5 to 10 micrometres equilibrated radius) over timescales spanning from 5 seconds to 20 minutes using a novel instrument to probe survival in a small population of droplets (typically 5-10) containing ~1 virus/droplet. Measurements of airborne infectivity change are coupled with a detailed physicochemical analysis of the airborne droplets containing the virus. A decrease in infectivity to 10 % of the starting value was observable for SARS-CoV-2 over 20 minutes, with a large proportion of the loss occurring within the first 5 minutes after aerosolisation. The initial rate of infectivity loss was found to correlate with physical transformation of the equilibrating droplet; salts within the droplets crystallise at RHs below 50% leading to a near instant loss of infectivity in 50 to 60% of the virus. However, at 90% RH the droplet remains homogenous and aqueous, and the viral stability is sustained for the first 2 minutes, beyond which it decays to only 10% remaining infectious after 10 minutes. The loss of infectivity at high RH is consistent with an elevation in the pH of the droplets, caused by volatilisation of CO2 from bicarbonate buffer within the droplet. Three different variants of SARS-CoV-2 were compared and found to have a similar degree of airborne stability at both high and low RH.

Macrofilaricidal Activity, Acute and Biochemical Effects of Three Lichen Species Found on Mount Cameroon

Onchocerciasis is a parasitic infection affecting a relatively small population globally but has very devastating pathological outcomes. Ivermectin and recently moxidectin are the only drugs approved for clinical management of the disease, both of which have several limitations. In particular, they are efficacious against microfilariae (microfilaricidal) with no activity against adult worms (nonmacrofilaricidal). Promising anthelmintic activity has been reported in some lichens. This study investigated three lichens, Usnea articulata, Parmotrema tinctorum, and Heterodermia obscurata, found on Mount Cameroon, for potential macrofilaricidal activity. Organic extracts were screened for anti-Onchocerca activity against Onchocerca ochengi isolated from cattle skin using worm motility and MTT formazan assays. Toxicity of highly active extracts was investigated on monkey kidney epithelial (LLCMK2) cells and in BALB/c mice (2000 mg/kg body weight) including effects on liver enzymes. The methanol extract of P. tinctorum (Pammet) was the most active against adult male worms ( I C 50 = 8.1 μg/mL) with the highest selectivity index ( SI = 21.3 ). U. articulata was the most active against the adult female ( I C 50 = 36.3 μg/mL) but had a low SI value (3.4). No mortality and no adverse effects were recorded in the acute toxicity test. These two most active extracts had no significant effect on liver enzymes, alanine aminotransferase, and aspartate ( P values < 0.05), but a high AST : ALT ratio (2.59) for Pammet indicates likely reversible adverse hepatic toxicity. The high macrofilaricidal activity and selectivity of P. tinctorum suggest it is a potential source of new macrofilaricides which should be further investigated to identify its bioactive constituents.

The Last Two Remaining Populations of the Critically Endangered Estuarine Pipefish Are Inbred and Not Genetically Distinct

The critically endangered estuarine pipefish, Syngnathus watermeyeri, is one of Africa’s rarest fish species and currently faces a significant risk of extinction. A combination of anthropogenic and natural factors threaten submerged macrophyte beds in the two South African estuaries (Bushmans and Kariega) in which the species’ only two known remaining populations reside. Here, we genotyped 34 pipefish from both populations using genome-wide data to determine whether the two estuaries harbour distinct genetic diversity, such that translocating individuals between them might improve the genetic health of both. Our results show that both populations are highly inbred, and no statistically significant genetic structure was found between them. Moreover, individuals both within and between estuaries were very closely related to each other. These results indicate that the remaining populations of the estuarine pipefish suffer from the adverse genetic effects of small population sizes. Even though recent surveys have estimated population sizes in the order of thousands of individuals, these may fluctuate considerably. Although the translocation of genetically similar individuals between habitats will not increase local genetic diversity, the creation of additional populations across the species’ historical range may be a suitable conservation strategy to prevent further loss of genetic diversity, and to minimise the overall extinction risk posed by environmental stochasticity.

Therapeutic Low-Intensity Ultrasound for Peripheral Nerve Regeneration – A Schwann Cell Perspective

Peripheral nerve injuries are common conditions that can arise from trauma (e.g., compression, severance) and can lead to neuropathic pain as well as motor and sensory deficits. Although much knowledge exists on the mechanisms of injury and nerve regeneration, treatments that ensure functional recovery following peripheral nerve injury are limited. Schwann cells, the supporting glial cells in peripheral nerves, orchestrate the response to nerve injury, by converting to a “repair” phenotype. However, nerve regeneration is often suboptimal in humans as the repair Schwann cells do not sustain their repair phenotype long enough to support the prolonged regeneration times required for successful nerve regrowth. Thus, numerous strategies are currently focused on promoting and extending the Schwann cells repair phenotype. Low-intensity ultrasound (LIU) is a non-destructive therapeutic approach which has been shown to facilitate peripheral nerve regeneration following nerve injury in rodents. Still, clinical trials in humans are scarce and limited to small population sizes. The benefit of LIU on nerve regeneration could possibly be mediated through the repair Schwann cells. In this review, we discuss the known and possible molecular mechanisms activated in response to LIU in repair Schwann cells to draw support and attention to LIU as a compelling regenerative treatment for peripheral nerve injury.

Expression of Vascular Endothelial Growth Factor in Uveal Melanoma

A prerequisite for the growth, progression and metastasis of malignant tumors of any localization is the development of its own vascular network. Newly formed vessels not only nourish the primary tumor, but also create conditions for the spread of tumor cells through the circulatory system and the formation of distant metastases. Angiogenesis is able to launch a small population of tumors from 100–300 cells that have accumulated genetic aberrations and have begun to express proangigenic molecules. The phenomenon is known as “transformation of tumor cells into angiogenic phenotype”. A tumor with angiogenic phenotype carries a high potential for proliferation and malignization. This pattern has been found in many types of cancer, but studied less in uveal melanoma. Meanwhile, in this aspect, uveal melanoma, metastasizing exclusively in a hematogenic way, with its selective, organotropic nature of metastasis, becomes an attractive model for the study of the molecular “scenario” of tumor angiogenesis studies allow us to say that, UM is subject to the general patterns of the development of malignant tumors. As with many types of tumors, VEGF is an obligate condition for the development and progression of UM. The VEGF molecule’s producers in UM are two cell populations: endothelial vascular cells and tumor cells. VEGF’s expression in UM is cyclical. The cycle is re-initiated, apparently, by increasing cell density in tumor proliferate and the development of hypoxia zones. We found no correlation between the intensity of pigmentation, necrosis, hemorrhage, germination in the corner of the front chamber, ophthalmohypertension on the one hand, and expression of VEGF in UM cells on the other. At the same time, a direct link between the expression of VEGF in tumor cells and EC vessels on the one hand and the thickness, base diameter, as well as the localization of UM, on the other hand, has been revealed. Additionally, VEGF expression in tumor cells was closely correlated with the histological structure of UM, and VEGF expression in EC correlated with the stage of the disease. Thus, the authors showed that UM, like other malignant solid tumors, is prone to transformation into angiogenic phenotype and expression of VEGF.

The Long-Term Effects of Living in a Shared and Continuous Traumatic Reality: The Case of Israeli Families on the Border With Gaza

This article presents a literature review of the concept of intergenerational transmission of traumatic stress among a specific population of Israeli parents and children living near the Israeli/Gaza border, an area that can essentially be viewed as a laboratory of shared, continuous, and stressful reality resulting from ongoing political violence. The Google Scholar database was used to search only for peer-reviewed articles written in English and published between 2002 and 2020, and the particular focus of the study was Israeli families living in the “Gaza envelope”: communities that have been on the receiving end of rockets and mortars from Gaza for the past 20 years. The review was based on 35 articles and sheds light on the existence of studies using a variety of perspectives (e.g., psychological, biopsychosocial, and behavioral). Findings demonstrate the effects of continuous stress situations on the family dynamic, even before birth, among this small population. In addition, they show that to understand the unique process of intergenerational trauma transmission in a shared continuous traumatic reality, it is important to adopt a comprehensive perspective so as to understand the reciprocal, long-lasting, and transgenerational effects of being exposed to traumatic stress. This perspective can be used as a basis for developing family intervention strategies that are appropriate for preventing stress outcomes that derive from living in the context of persistent violence.

Epicardial Box Lesion Using Bipolar Biparietal Radiofrequency and Multimodality Scar Evaluation - a case series

Background Surgical epicardial AF ablation can be performed as a stand-alone (thoracoscopic) procedure or concomitant to other cardiac surgery. In hybrid AF ablation thoracoscopic surgical epicardial ablation is combined with a percutaneous endocardial ablation. The Medtronic Gemini-S clamp is a surgical tool that uses irrigated bipolar biparietal RF energy applied with two clamp lesions that overlap to create one epicardial box lesion including the posterior LA wall and the pulmonary veins. Case summary We describe three patients with therapy-refractory persistent AF and different stages of atrial remodelling in whom the Medtronic Cardioblate Gemini-S Irrigated RF Surgical Ablation System was used for hybrid AF ablation. Acute endocardial validation at the end of the hybrid ablation revealed a complete box lesion in all three cases. At 2-year follow-up, two out of three patients had recurrence of atrial arrhythmias. Invasive electro-anatomical mapping confirmed persistence of the box lesion, and the mechanism of arrhythmia recurrence in both patients was unrelated to posterior left atrium or the pulmonary veins. The third patient has been without arrhythmia symptoms since the ablation procedure. A 3D late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) illustrates the ablation scar non-invasively in two cases. Discussion Thoracoscopic biparietal RF AF ablation with the Medtronic Cardioblate Gemini-S Irrigated RF Surgical Ablation System results in permanent transmural scar formation, irrespective of the stage of atrial remodelling, as shown in this small population by means of multimodality scar evaluation.

Calibrating Variable-Value Population Ethics

Variable-Value axiologies propose solutions to the challenges of population ethics. These views avoid Parfit’s Repugnant Conclusion, while satisfying some weak instances of the Mere Addition principle (for example, at small population sizes). We apply calibration methods to Variable-Value views while assuming: first, some very weak instances of Mere Addition, and, second, some plausible empirical assumptions about the size and welfare of the intertemporal world population. We find that Variable-Value views imply conclusions that should seem repugnant to anyone who opposes Total Utilitarianism due to the Repugnant Conclusion. So, any wish to avoid repugnant conclusions is not a good reason to choose a Variable-Value view. More broadly, these calibrations teach us something about the effort to avoid the Repugnant Conclusion. Our results join a recent literature arguing that prior efforts to avoid the Repugnant Conclusion hinge on inessential features of the formalization of repugnance. Some of this effort may therefore be misplaced.

The Wattled-Wall House of Salar People and Its Conservation and Development

Salar people are Turkic-speaking Islamic people and an ethnic group with a small population in China. Wattled-wall house of Salar people is a type of traditional house threatened by extinction. In 2008, the wattled-wall house construction skills were selected for the national intangible cultural heritage list. It is mainly distributed in Xunhua Salar Autonomous County, Qinghai Province of China. So far, Salar people′s traditional wattled-wall house knowledge has been poorly documented. Therefore, a study supporting cultural preservation efforts is needed, including preserving plants used in its construction. This study mainly applied ethnobotanical methods based on data collection through observation, interviews, and documentation. Additionally, ArcGIS data analysis is also used to supplement the evaluation of the traditional wattled-wall house. This study aimed to (1) document traditional knowledge about the wattled-wall house construction, (2) and evaluate the current status of the wattled-wall house from different angles like the environmental adaptability and internal advantages and disadvantages. The result showed that the local people still apply the knowledge about the wattled-wall house from generation to generation. However, due to some practical reasons, the wattled-wall house is on the verge of extinction. There are 11 plant taxa used as construction materials in wattled-wall house. Conservation efforts for species involved in the wattled-wall house are needed, especially the ones with limited availability. Re-use of wattled-wall house is needed in order to maximize the economic benefits and to safeguard its historical and architectural values. It is recommended that the conservation of this cultural heritage needs more attention and effort from the local government or the society.

Conservation genetics as a management tool: The five best-supported paradigms to assist the management of threatened species

About 50 y ago, Crow and Kimura [An Introduction to Population Genetics Theory (1970)] and Ohta and Kimura [Genet. Res. 22, 201–204 (1973)] laid the foundations of conservation genetics by predicting the relationship between population size and genetic marker diversity. This work sparked an enormous research effort investigating the importance of population dynamics, in particular small population size, for population mean performance, population viability, and evolutionary potential. In light of a recent perspective [J. C. Teixeira, C. D. Huber, Proc. Natl. Acad. Sci. U.S.A. 118, 10 (2021)] that challenges some fundamental assumptions in conservation genetics, it is timely to summarize what the field has achieved, what robust patterns have emerged, and worthwhile future research directions. We consider theory and methodological breakthroughs that have helped management, and we outline some fundamental and applied challenges for conservation genetics.