Higher Temperatures in Socially Vulnerable US Communities Increasingly Limit Safe Use of Electric Fans for Cooling

As the globe warms, people will increasingly need affordable, safe methods to stay cool and minimize the worst health impacts of heat exposure. One of the cheapest cooling methods is electric fans. Recent research has recommended ambient air temperature thresholds for safe fan use in adults. Here we use hourly weather reanalysis data (1950-2021) to examine the temporal and spatial evolution of ambient climate conditions in the continental United States (CONUS) considered safe for fan use, focusing on high social vulnerability index (SVI) regions. We find that although most hours in the day are safe for fan use, there are regions that experience hundreds to thousands of hours per year that are too hot for safe fan use. Over the last several decades, the number of hours considered unsafe for fan use has increased across most of the CONUS (on average by ∼70%), with hotspots across the US West and South, suggesting that many individuals will increasingly need alternative cooling strategies. People living in high-SVI locations are 1.5-2 times more likely to experience hotter climate conditions than the overall US population. High-SVI locations also experience higher rates of warming that are approaching and exceeding important safety thresholds that relate to climate adaptation. These results highlight the need to direct additional resources to these communities for heat adaptive strategies.

"3D, human renal proximal tubule (RPTEC-TERT1) organoids 'tubuloids' for translatable evaluation of nephrotoxins in high-throughput"

The importance of human cell-based in vitro tools to drug development that are robust, accurate, and predictive cannot be understated. There has been significant effort in recent years to develop such platforms, with increased interest in 3D models that can recapitulate key aspects of biology that 2D models might not be able to deliver. We describe the development of a 3D human cell-based in vitro assay for the investigation of nephrotoxicity, using RPTEC-TERT1 cells. These RPTEC-TERT1 proximal tubule organoids 'tubuloids' demonstrate marked differences in physiologically relevant morphology compared to 2D monolayer cells, increased sensitivity to nephrotoxins observable via secreted protein, and with a higher degree of similarity to native human kidney tissue. Finally, tubuloids incubated with nephrotoxins demonstrate altered Na+/K+-ATPase signal intensity, a potential avenue for a high-throughput, translatable nephrotoxicity assay.

A cell-level quality control workflow for high-throughput image analysis

BACKGROUND

Image-based high throughput (HT) screening provides a rich source of information on dynamic cellular response to external perturbations. The large quantity of data generated necessitates computer-aided quality control (QC) methodologies to flag imaging and staining artifacts. Existing image- or patch-level QC methods require separate thresholds to be simultaneously tuned for each image quality metric used, and also struggle to distinguish between artifacts and valid cellular phenotypes. As a result, extensive time and effort must be spent on per-assay QC feature thresholding, and valid images and phenotypes may be discarded while image- and cell-level artifacts go undetected.

RESULTS

We present a novel cell-level QC workflow built on machine learning approaches for classifying artifacts from HT image data. First, a phenotype sampler based on unlabeled clustering collects a comprehensive subset of cellular phenotypes, requiring only the inspection of a handful of images per phenotype for validity. A set of one-class support vector machines are then trained on each biologically valid image phenotype, and used to classify individual objects in each image as valid cells or artifacts. We apply this workflow to two real-world large-scale HT image datasets and observe that the ratio of artifact to total object area (AR_cell) provides a single robust assessment of image quality regardless of the underlying causes of quality issues. Gating on this single intuitive metric, partially contaminated images can be salvaged and highly contaminated images can be excluded before image-level phenotype summary, enabling a more reliable characterization of cellular response dynamics.

CONCLUSIONS

Our cell-level QC workflow enables identification of artificial cells created not only by staining or imaging artifacts but also by the limitations of image segmentation algorithms. The single readout AR_cell that summaries the ratio of artifacts contained in each image can be used to reliably rank images by quality and more accurately determine QC cutoff thresholds. Machine learning-based cellular phenotype clustering and sampling reduces the amount of manual work required for training example collection. Our QC workflow automatically handles assay-specific phenotypic variations and generalizes to different HT image assays.

A chemical biology approach to myocardial regeneration

Heart failure is one of the major causes of death in the Western world because cardiac muscle loss is largely irreversible and can lead to a relentless decline in cardiac function. Novel therapies are needed since the only therapy to effectively replace lost myocytes today is transplantation of the entire heart. The advent of embryonic and induced pluripotent stem cell (ESC/iPSC) technologies offers the unprecedented possibility of devising cell replacement therapies for numerous degenerative disorders. Not only are ESCs and iPSCs a plausible source of cardiomyocytes in vitro for transplantation, they are also useful tools to elucidate the biology of stem cells that reside in the adult heart and define signaling molecules that might enhance the limited regenerative capability of the adult human heart. Here, we review the extracellular factors that control stem cell cardiomyogenesis and describe new approaches that combine embryology with stem cell biology to discover drug-like small molecules that stimulate cardiogenesis and potentially contribute to the development of pharmaceutical strategies for heart muscle regeneration.

Disruption of ShcA signaling halts cell proliferation--characterization of ShcC residues that influence signaling pathways using yeast

Shc adapter proteins are thought to regulate cellular proliferation, differentiation and apoptosis by activating the SOS-Grb2-RAS-MAPK signaling cascade. Using the small hairpin RNA (shRNA) technique, we found that decreasing ShcA mRNA reduced the proliferative ability of HEK293 mammalian culture cells. We then recapitulated phosphorylation-dependent Shc-Grb2 complex formation in Saccharomyces cerevisiae. Immunoprecipitation followed by Western analysis demonstrated that activated TrkB, composed of the intracellular domain of TrkB fused to glutathione S-transferase (GST-TrkB(ICD)), promoted the association of ShcC and Grb2 in yeast. The Ras-recruitment system (RRS), in which a myristoylated (Myr)-bait and son of sevenless (hSOS)-prey are brought together to complement the defective Ras-cAMP pathway in a thermosensitive cdc25H mutant yeast strain, was used to validate a phenotypic assay. Yeast cells transformed with both Myr-ShcC and hSOS-Grb2 (referred to as scheme 1) or Myr-Grb2 and hSOS-ShcC (scheme 2) did not grow at non-permissive temperature; the additional transformation of GST-TrkB(ICD) enabled growth. GST-TrkB(ICD) also enabled growth with hSOS-Grb2 and either Myr-ShcA or Myr-SHP2. Mutational analysis of TrkB showed that its kinase activity was essential for complementation, while its docking site for Shc proteins was not. Mutational analysis of ShcC showed that the PTB and SH2 domains were not essential for complementation but phosphorylation at Y304 in the CH1 domain was. Phosphorylation at Y304 could not be substituted by an acidic amino acid. The RRS provides a genetic system to probe Shc proteins and potentially identify member specific protein partners and pharmacological reagents.

Effect of 5α-pregnan-3α-ol-20-one on nitric oxide biosynthesis and plasma volume in rats

Plasma 5α-pregnan-3α-ol-20-one (pregnan) levels and nitric oxide (NO) biosynthesis increase during pregnancy. These factors have independently been implicated in the control of blood pressure and volume. We wished to determine whether pregnan might be responsible both for the increase in NO biosynthesis and for the increase in plasma volume observed during pregnancy. Virgin female Long-Evans rats were implanted with indwelling cannulas and maintained on a low nitrate/nitrite diet. After the rats recovered from surgery, 500 μg of pregnan or vehicle were given daily for 2 days. NO biosynthesis and plasma volume were measured in conscious animals before and after treatment. Pregnan caused a significant increase in NO biosynthesis (1.9 ± 0.8 μmol/24 h, n = 10) compared with the vehicle-treated control group (0.3 ± 0.4 μmol/24 h, n = 10, P < 0.05). Similarly, there was a significant increase in plasma volume in the pregnan-treated group (0.7 ± 0.2 ml/100 g, n = 11) compared with the vehicle-treated control group (0.2 ± 0.1 ml/100 g, n = 11, P < 0.05). These results confirm that pregnan can mimic pregnancy by its ability to increase both NO biosynthesis and plasma volume.

Nitric oxide, impulse activity, and neurotrophins in visual system development(1)

Topographic refinement of synaptic connections within the developing visual system involves a variety of molecules which interact with impulse activity in order to produce the precise retinotopic maps found in the adult brain. Nitric oxide (NO) has been implicated in this process, as have various growth factors. Within the subcortical visual system, we have recently shown that nitric oxide contributes to pathway refinement in the superior colliculus (SC). Long-term potentiation (LTP) and long-term depression (LTD) are also expressed in SC during the time that this pathway undergoes refinement. The role of NO has been demonstrated by showing that refinement of ipsilateral fibers in the retinocollicular pathway is significantly delayed in gene knockout mice in which both the endothelial and neuronal isoforms of nitric oxide synthase (NOS) have been disrupted. The effect also depends upon Ca(2+) channels because refinement of both the ipsilateral retinocollicular and retinogeniculate pathways is disrupted in genetic mutants in which the beta3 subunit of the Ca(2+) channel has been deleted. LTD may also be involved in this process, because the time course of its expression correlates with that of pathway refinement and LTD magnitude is depressed by nitrendipine, an L-type Ca(2+) channel blocker. LTP is also expressed during early postnatal development in the LGN and SC and may contribute to synaptic stabilization. The role of neurotrophins in pathway refinement in the visual system is also reviewed.

What is the value of the lateral chest radiograph in the follow-up thoracic lymphoma?

Lateral chest radiography in the investigation of thoracic lymphoma remains a feature of the current literature. This study assessed what information the lateral chest radiograph (CXR) adds in the follow-up of such patients. Eighty-eight patients with known lymphoma who had a CXR and thoracic CT within the same 4-week period were assessed. Five radiologists scored eight mediastinal and hilar nodal groups and eight extramediastinal regions on the frontal CXR as normal, equivocal or definitely abnormal (denoted 0, 1 and 2, respectively). This was repeated 1 week later with a combination of frontal and lateral films. Results were compared with the findings on CT which were scored similarly using accepted criteria for the presence of lymphadenopathy. Where the lateral CXR caused a change in score at any site, this change was compared with CT to determine the effect on diagnostic accuracy. For four of the five observers, the lateral film made no significant difference in diagnostic accuracy in the assessment of mediastinal lymph nodes. A fifth observer derived a small benefit from the addition of the lateral film, although almost 30 % of this was accounted for by changing from a wrong to an equivocal diagnosis. The lateral film did cause a small increase in the detection of pleuro-parenchymal lung lesions, although none of these were clinically significant. We conclude that routine lateral chest radiography is unhelpful in the follow-up of patients with lymphoma.