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CDC recommends a combination of evidence-based strategies to reduce transmission of SARS-CoV-2, the virus that causes COVID-19 (1). Because the virus is transmitted predominantly by inhaling respiratory droplets from infected persons, universal mask use can help reduce transmission (1). Starting in April, 39 states and the District of Columbia (DC) issued mask mandates in 2020. Reducing person-to-person interactions by avoiding nonessential shared spaces, such as restaurants, where interactions are typically unmasked and physical distancing (≥6 ft) is difficult to maintain, can also decrease transmission (2). In March and April 2020, 49 states and DC prohibited any on-premises dining at restaurants, but by mid-June, all states and DC had lifted these restrictions. To examine the association of state-issued mask mandates and allowing on-premises restaurant dining with COVID-19 cases and deaths during March 1-December 31, 2020, county-level data on mask mandates and restaurant reopenings were compared with county-level changes in COVID-19 case and death growth rates relative to the mandate implementation and reopening dates. Mask mandates were associated with decreases in daily COVID-19 case and death growth rates 1-20, 21-40, 41-60, 61-80, and 81-100 days after implementation. Allowing any on-premises dining at restaurants was associated with increases in daily COVID-19 case growth rates 41-60, 61-80, and 81-100 days after reopening, and increases in daily COVID-19 death growth rates 61-80 and 81-100 days after reopening. Implementing mask mandates was associated with reduced SARS-CoV-2 transmission, whereas reopening restaurants for on-premises dining was associated with increased transmission. Policies that require universal mask use and restrict any on-premises restaurant dining are important components of a comprehensive strategy to reduce exposure to and transmission of SARS-CoV-2 (1). Such efforts are increasingly important given the emergence of highly transmissible SARS-CoV-2 variants in the United States (3,4).

Long-standing systemic social, economic, and environmental inequities in the United States have put many communities of color (racial and ethnic minority groups) at increased risk for exposure to and infection with SARS-CoV-2, the virus that causes COVID-19, as well as more severe COVID-19-related outcomes (1-3). Because race and ethnicity are missing for a proportion of reported COVID-19 cases, counties with substantial missing information often are excluded from analyses of disparities (4). Thus, as a complement to these case-based analyses, population-based studies can help direct public health interventions. Using data from the 50 states and the District of Columbia (DC), CDC identified counties where five racial and ethnic minority groups (Hispanic or Latino [Hispanic], non-Hispanic Black or African American [Black], non-Hispanic Asian [Asian], non-Hispanic American Indian or Alaska Native [AI/AN], and non-Hispanic Native Hawaiian or other Pacific Islander [NH/PI]) might have experienced high COVID-19 impact during April 1-December 22, 2020. These counties had high 2-week COVID-19 incidences (>100 new cases per 100,000 persons in the total population) and percentages of persons in five racial and ethnic groups that were larger than the national percentages (denoted as "large"). During April 1-14, a total of 359 (11.4%) of 3,142 U.S. counties reported high COVID-19 incidence, including 28.7% of counties with large percentages of Asian persons and 27.9% of counties with large percentages of Black persons. During August 5-18, high COVID-19 incidence was reported by 2,034 (64.7%) counties, including 92.4% of counties with large percentages of Black persons and 74.5% of counties with large percentages of Hispanic persons. During December 9-22, high COVID-19 incidence was reported by 3,114 (99.1%) counties, including >95% of those with large percentages of persons in each of the five racial and ethnic minority groups. The findings of this population-based analysis complement those of case-based analyses. In jurisdictions with substantial missing race and ethnicity information, this method could be applied to smaller geographic areas, to identify communities of color that might be experiencing high potential COVID-19 impact. As areas with high rates of new infection change over time, public health efforts can be tailored to the needs of communities of color as the pandemic evolves and integrated with longer-term plans to improve health equity.

t-Butyl hydroperoxide has been studied as a possible competitive inhibitor of the vitamin K-dependent carboxylation of the pentapeptide PheLeuGluGluIle. Under standard carboxylating conditions the concentrations of reduced phylloquinone and phylloquinone were followed by high-pressure liquid chromatography during 30-min incubations of Triton-solubilized microsomes from rat liver. Under these conditions supporting linear rates of carbon dioxide fixation for 20–30 min, the vitamin KH2 concentration decreased exponentially to less than 5% of its initial value in 30 min principally due to autooxidation. In the presence of 10 m m t-butyl-OOH, however, the oxidation of vitamin KH2 was greatly accelerated with none being detected after 7 min. In general, the rate of carboxylation of peptide paralleled the KH2 concentration. After cessation of carboxylation in the presence of t-butyl-OOH the readdition of KH2 stimulated additional 14CO2 fixation. A known competitive inhibitor of vitamin K, 2-chlorophylloquinone, did not accelerate the oxidation of KH2 but nonetheless inhibited the vitamin K-dependent carboxylation in a competitive manner. These data have led us to conclude that t-butyl-OOH is not a competitive inhibitor of the vitamin K-dependent carboxylase at the active site of the enzyme but merely acts to promote the oxidation of KH2.

The alkylation of menaquinone-0 to menaquinones occurs in the microsomal fraction of chick and rat liver. Subfractionation of chick microsomes into smooth and rough reticulum was achieved by density gradient centrifugation. The alkylation enzyme was localized in the smooth reticulum with an activity of 155 pmol/mg per h, about 50-fold greater than that in the rough reticulum. The membrane-bound alkylating enzyme system requires reduced menaquinone-0 and is phospholipid-dependent.

The ultraviolet absorption spectra of aqueous and alcoholic solutions of the pyridinemono-carboxylic acids and amides, of the vicinal pyridinedicarboxylic acids, and of the 1-oxides of these compounds, were measured and qualitatively interpreted. The photolysis of the 1-oxides in aqueous solution resulted principally in their deoxygenation. Photolysis of picolinamide 1-oxide also gave a rearrangement product, 1-formyl-2-pyrrolecarboxamide. The photolyses of the 2- and 4-monosubstituted 1-oxides were somewhat faster than those of the 3-substituted 1-oxides. The experimental results are discussed in terms of possible hydrogen-bonding effects.

Synthetic lysophosphatidylethanolamine (LPE) obtained from commercial sources augmented the apparent activity of phospholipase A2 (PLA2) in cardiac mitochondrial and microsomal fractions. For elucidation of this phenomenon, 2-[1-14C]linoleylphosphatidylethanolamine was incubated in the absence of cell protein with selected concentrations of LPE, lysophosphatidylcholine (LPC), Ca2+, ionic and nonionic detergents, and phospholipids with functional groups similar to those of LPE. Hydrolysis of phosphatidylethanolamine (PE) was evaluated by measurement of 14C-labeled free fatty acid release and confirmed by quantification of [14C]ethanolamine-labeled LPE formed. The reaction was dependent on the concentrations of Ca2+, PE, and LPE, exceeding 1.5 nmol/h with 20 micro M LPE and 30 micro M PE. Hydrolysis occurred in the presence of as little as 1 micro M LPE. PE was not hydrolyzed by comparable concentrations of ionic or nonionic detergents or by several closely related phosphatides, including LPC. Purification of synthetic LPE by high-performance LC to remove contaminating PLA2 eliminated the effect. LPE-induced hydrolysis of PE was found to depend on contamination of the LPE by PLA2 from Crotalus atrox, employed in the commercial synthesis of the lysophosphatide from the precursor used, phosphatidylethanolamine. Contamination of commercially obtained lysophosphoglycerides by PLA2 constitutes a technical pitfall which may cloud interpretation of experiments performed with inadequately purified material.

Publisher Summary Saccharomyces cerevisiae αS288C is a strain of baker's yeast that is widely used for genetic studies. This well-characterized organism is suitable for the preparation of both tRNA and amino acid:tRNA ligases. This organism has been strongly recommended, or an isogenic strain, for all biochemical studies involving yeast tRNA and its related enzymes. This chapter describe the preparation of homogeneous amino acid:tRNA ligases specific for tyrosine, alanine, ratine, and isoleucine from Saccharomyces cerevisiae αS288C. These ligases are the first to be reported from this organism. It is believed that the procedures described will prove generally applicable for most, if not all, of the amino acid:tRNA ligases from this organism. The chapter discusses the properties of these enzymes. The molecular weight and subunit structure of the amino acid:tRNA ligases are determined under denaturing conditions by discontinuous polyacrylamide gel electrophoresis in the presence of 1% sodium dodecyl sulfate.

The COVID-19 pandemic has resulted in a disproportionate burden on racial and ethnic minority groups, but incompleteness in surveillance data limits understanding of disparities. CDC's case-based surveillance system contains case-level information on most COVID-19 cases in the United States. Data analyzed in this paper contain COVID-19 cases with case-level information through September 25, 2020, which represent 70.9% of all COVID-19 cases reported to CDC during the period. Case-level surveillance data are used to investigate COVID-19 disparities by race/ethnicity, sex, and age. However, demographic information on race and ethnicity is missing for a substantial percentage of COVID-19 cases (e.g., 35.8% and 47.2% of cases analyzed were missing race and ethnicity information, respectively). Our goal in this study was to impute missing race and ethnicity to derive more accurate incidence and incidence rate ratio (IRR) estimates for different racial and ethnic groups, and evaluate the results from imputation compared to complete case analysis, which involves removing cases with missing race/ethnicity information from the analysis. Two multiple imputation (MI) models were developed. Model 1 imputes race using six binary race variables, and Model 2 imputes race as a composite multinomial variable. Our evaluation found that compared with complete case analysis, MI reduced biases and improved coverage on incidence and IRR estimates for all race/ethnicity groups, except for the Non-Hispanic Multiple/other group. Our research highlights the importance of supplementing complete case analysis with additional methods of analysis to better describe racial and ethnic disparities. When race and ethnicity data are missing, multiple imputation may provide more accurate incidence and IRR estimates to monitor these disparities in tandem with efforts to improve the collection of race and ethnicity information for pandemic surveillance.