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We used unbiased metagenomic next-generation sequencing to diagnose a fatal case of meningoencephalitis caused by St. Louis encephalitis virus in a patient from California in September 2016. This case is associated with the recent 2015-2016 reemergence of this virus in the southwestern United States. [ABSTRACT FROM AUTHOR]

Background Guidelines support the use of toxin tests after C. difficile antigen detection or nucleic acid amplification tests (e.g. PCR) to help clinicians distinguish colonization from infection and reduce overdiagnosis but the safety of toxin-based diagnostic approaches remains controversial. Methods Five California hospitals monitored hospitalized adults with C. difficile testing before and after operational changes to reduce test-related overdiagnosis (2016–2018). Four added a toxin test to an existing GDH antigen/PCR-based approach and/or changed reporting to encourage the use of toxin results for clinical decision-making (i.e."toxin-dominant reporting"). One used the same test (toxin only) and reporting strategy throughout. All used a standardized tool to document clinical outcomes and treatment four days after testing (i.e. Day 5). Results In total, 1,034 patients had a Day 5 assessment with PCR-dominant reporting (pre-operational changes); 2,511 patients had a Day 5 assessment with toxin-dominant reporting (post-operational changes and single facility with no test change). Fewer Toxin-negative/PCR-positive (Toxin−/PCR+) patients received treatment with toxin-dominant reporting (median change: −52.1% [interquartile range (IQR): −35.1%, −69.1%]; aggregate P < 0.001). Day 5 outcomes were similar or better with toxin-dominant reporting despite less treatment. Patient discharge rates and in hospital diarrheal recovery was greater in the subset of Toxin−/PCR+ patients during the toxin-dominant reporting period: median discharge rate change = 8.8% [IQR: 1.5%, 11.9%] (aggregate P = 0.04); median diarrheal recovery rate change = 11.8% [IQR: 8.8%, 18.2%] (aggregate P = 0.018). Conclusion In a 5-center study, toxin-dominant test result reporting decreased anti- C. difficile treatment and improved discharge rates and diarrheal recovery in Toxin−/PCR+ patients. More work is needed to determine the rate of C. difficile -related adverse events in Toxin−/PCR+ patients. Disclosures All Authors: No reported Disclosures. [ABSTRACT FROM AUTHOR]

The article presents a study by Beth L. Pruitt and colleagues at the Stanford University on measuring a nematode with a piezoresistor. According to Pruitt, understanding the mechanics of the nematode structures, the internal linkages between the cuticle and the organs inside, will enable to understand the force transmission and the underlying mechanisms for the sense of touch and locomotion. The researchers used optical tweezers and atomic force microscopy (AFM) to measure small displacement and forces. Furthermore, they found that the relationship between force and displacement is consistent with an elastic-shell-type model of the animal's body and hydrostatic pressure had a contribution to the stiffness of the outer shell compared with the contribution of cuticle mechanics.

The article presents information on a new hand-held endoscopic fluorescence imaging device for live tissue imaging, developed by Mark Schnitzer and colleagues at Stanford University, Palo Alto, California. The device, which relies on a two-photon system to excite electrons in the target molecule, produces clearer images than conventional single-photon fluorescence imaging systems. Two-photon system reduces image haziness because it restricts fluorescence generation to the focal point the laser that provides the photons. Schnitzer's group created the miniaturized two-photon system with a tiny endoscopic probe both to focus the excitation light on the point of interest and to collect the fluorescence emissions. The researchers used the device to obtain images of the blood vessels in the hippocampal regions of live mice. Thomas Gensch of the Institute of Biological Information Processing, Germany, agrees that this portable two-photon fluorescence microendoscope has the potential to develop and perform less destructive, more practical, and cost-saving fluorescence microscopy-based studies on viable cells, tissue, and organisms.

We present a 17-year calibration record of precise (Jason-class) spaceborne altimetry from a California offshore oil platform (Harvest). Our analyses indicate that the sea-surface-height (SSH) biases for all three TOPEX/Poseidon (1992-2005) measurement systems are statistically indistinguishable from zero at the 15 mm level. In contrast, the SSH bias estimates for the newer Jason-1 mission (2001-present) and the Ocean Surface Topography Mission (2008-present) are significantly positive. In orbit for over eight years, the Jason-1 measurement system yields SSH biased by +94 ± 15 mm. Its successor, OSTM/Jason-2, produces SSH measurements biased by +178 ± 16 mm. [ABSTRACT FROM AUTHOR]

We identified an emerging severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant by viral whole-genome sequencing of 2,172 nasal/nasopharyngeal swab samples from 44 counties in California, a state in the western United States. Named B.1.427/B.1.429 to denote its two lineages, the variant emerged in May 2020 and increased from 0% to >50% of sequenced cases from September 2020 to January 2021, showing 18.6%–24% increased transmissibility relative to wild-type circulating strains. The variant carries three mutations in the spike protein, including an L452R substitution. We found 2-fold increased B.1.427/B.1.429 viral shedding in vivo and increased L452R pseudovirus infection of cell cultures and lung organoids, albeit decreased relative to pseudoviruses carrying the N501Y mutation common to variants B.1.1.7, B.1.351, and P.1. Antibody neutralization assays revealed 4.0- to 6.7-fold and 2.0-fold decreases in neutralizing titers from convalescent patients and vaccine recipients, respectively. The increased prevalence of a more transmissible variant in California exhibiting decreased antibody neutralization warrants further investigation. [Display omitted] • The B.1.427/B.1.429 variant grew to >50% of cases in California by early 2021 • The variant is 20% more transmissible with 2-fold increased shedding in vivo • The variant has a spike L452R mutation conferring increased infectivity in vitro • Antibody neutralization is reduced in COVID-19 patients and vaccine recipients A SARS-CoV-2 variant of concern bearing the L452R spike protein mutation is widely circulating in California, United States, and demonstrates increased transmissibility, infectivity, and avoidance of antibody neutralization. [ABSTRACT FROM AUTHOR]