Technical note: Understanding the effect of COVID-19 on particle pollution using a low-cost sensor network.

The 2020 coronavirus pandemic and the following quarantine measures have led to significant changes in daily life worldwide. Preliminary research indicates that air quality has improved in many urban areas as a result of these measures. This study takes a neighborhood-scale approach to quantifying this change in pollution. Using data from a network of citizen-hosted, low-cost particulate matter (PM) sensors, called Air Quality & yoU (AQ&U), we obtained high-spatial resolution measurements compared to the relatively sparse state monitoring stations. We compared monthly average estimated PM2.5 concentrations from February 11 to May 11, 2019 at 71 unique locations in Salt Lake County, UT, USA with the same (71) sensors' measurements during the same timeframe in 2020. A paired t-test showed significant reductions (71.1% and 21.3%) in estimated monthly PM2.5 concentrations from 2019 to 2020 for the periods from March 11-April 10 and April 11-May 10, respectively. The March time period corresponded to the most stringent COVID-19 related restrictions in this region. Significant decreases in PM2.5 were also reported by state monitoring sites during March (p < 0.001 compared to the previous 5-year average). While we observed decreases in PM2.5 concentrations across the valley in 2020, it is important to note that the PM2.5 concentrations did not improve equally in all locations. We observed the greatest reductions at lower elevation, more urbanized areas, likely because of the already low levels of PM2.5 at the higher elevation, more residential areas, which were generally below 2 µg/m3 in both 2019 and 2020. Although many of measurements during March and April were near or below the estimated detection limit of the low-cost PM sensors and the federal equivalent measurements, every low-cost sensor (51) showed a reduction in PM2.5 concentration in March of 2020 compared to 2019. These results suggest that the air quality improvement seen after March 11, 2020 is due to quarantine measures reducing traffic and decreasing pollutant emissions in the region.

FtsZ Reorganization Facilitates Deformation of Giant Vesicles in Microfluidic Traps*.

The geometry of reaction compartments can affect the local outcome of interface-restricted reactions. Giant unilamellar vesicles (GUVs) are commonly used to generate cell-sized, membrane-bound reaction compartments, which are, however, always spherical. Herein, we report the development of a microfluidic chip to trap and reversibly deform GUVs into cigar-like shapes. When trapping and elongating GUVs that contain the primary protein of the bacterial Z ring, FtsZ, we find that membrane-bound FtsZ filaments align preferentially with the short GUV axis. When GUVs are released from this confinement and membrane tension is relaxed, FtsZ reorganizes reversibly from filaments into dynamic rings that stabilize membrane protrusions; a process that allows reversible GUV deformation. We conclude that microfluidic traps are useful for manipulating both geometry and tension of GUVs, and for investigating how both affect the outcome of spatially-sensitive reactions inside them, such as that of protein self-organization.

Fibroblast growth factor-21 (FGF21) administration to early-lactating dairy cows. II. Pharmacokinetics, whole-animal performance, and lipid metabolism.

Dairy cows cope with severe energy insufficiency in early lactation by engaging in intense and sustained mobilization of fatty acids from adipose tissue. An unwanted side effect of this adaptation is excessive lipid accumulation in the liver, which in turn impairs hepatic functions. Mice experiencing increased hepatic fatty acid flux are protected from this condition through coordinated actions of the newly described hormone fibroblast growth factor-21 (FGF21) on liver and adipose tissue. The possibility of an analogous role for FGF21 in dairy cows is suggested by its rapid increase in plasma levels around parturition followed by chronically elevated levels in the first few weeks of lactation. To test this hypothesis, dairy cows were randomly assigned on d 12.6 ± 2.2 (± standard error) of lactation to receive either an excipient (control; n = 6) or recombinant human FGF21 (n = 7), first as an FGF21 bolus of 3 mg/kg of body weight (BW) followed 2 d later by a constant i.v. infusion of FGF21 at a rate of 6.3 mg/kg of metabolic BW for 9 consecutive days. After bolus administration, human FGF21 circulated with a half-life of 194 min, and its constant infusion increased total plasma concentration 117-fold over levels in excipient-infused cows. The FGF21 treatment had no effect on voluntary feed intake, milk yield, milk energy output, or net energy balance measured over the 9-d infusion or on final BW. Plasma fatty acids circulated at lower concentrations in the FGF21 group than in the control group for the 8-h period following bolus administration, but this reduction was not significant during the period of constant i.v. infusion. Treatment with FGF21 caused a 50% reduction in triglyceride content in liver biopsies taken at the end of the constant i.v. infusion without altering the mRNA abundance of key genes involved in the transport, acyl coenzyme A activation, or oxidation of fatty acids. In contrast, FGF21 treatment ablated the recovery of plasma insulin-like growth factor-1 seen in control cows during the 9-d i.v. infusion period despite a tendency for higher plasma growth hormone. This effect was associated with increased hepatic mRNA abundance of the intracellular inhibitor of growth hormone receptor trafficking, LEPROT. Overall, these data confirm the ability of FGF21 to reduce lipid accumulation in bovine liver and suggest the possibility that FGF21 does so by attenuating the hepatic influx of adipose tissue-derived fatty acids.

Long-term field evaluation of the Plantower PMS low-cost particulate matter sensors.

The low-cost and compact size of light-scattering-based particulate matter (PM) sensors provide an opportunity for improved spatiotemporally resolved PM measurements. However, these inexpensive sensors have limitations and need to be characterized under realistic conditions. This study evaluated two Plantower PMS (particulate matter sensor) 1003s and two PMS 5003s outdoors in Salt Lake City, Utah over 320 days (1/2016-2/2016 and 12/2016-10/2017) through multiple seasons and a variety of elevated PM2.5 events including wintertime cold-air pools (CAPs), fireworks, and wildfires. The PMS 1003/5003 sensors generally tracked PM2.5 concentrations compared to co-located reference air monitors (one tapered element oscillating microbalance, TEOM, and one gravimetric federal reference method, FRM). The different PMS sensor models and sets of the same sensor model exhibited some intra-sensor variability. During winter 2017, the two PMS 1003s consistently overestimated PM2.5 by a factor of 1.89 (TEOM PM2.5<40 µg/m3). However, compared to the TEOM, one PMS 5003 overestimated PM2.5 concentrations by a factor of 1.47 while the other roughly agreed with the TEOM. The PMS sensor response also differed by season. In two consecutive winters, the PMS PM2.5 measurements correlated with the hourly TEOM measurements (R2 > 0.87) and 24-h FRM measurements (R2 > 0.88) while in spring (March-June) and wildfire season (June-October) 2017, the correlations were poorer (R2 of 0.18-0.32 and 0.48-0.72, respectively). The PMS 1003s maintained high intra-sensor agreement after one year of deployment during the winter seasons, however, one PMS 1003 sensor exhibited a significant drift beginning in March 2017 and continued to deteriorate through the end of the study. Overall, this study demonstrated good correlations between the PMS sensors and reference monitors in the winter season, seasonal differences in sensor performance, some intra-sensor variability, and drift in one sensor. These types of factors should be considered when using measurements from a network of low-cost PM sensors.

Development of a calibration chamber to evaluate the performance of low-cost particulate matter sensors.

Low-cost particulate matter (PM) air quality sensors are becoming widely available and are being increasingly deployed in ambient and home/workplace environments due to their low cost, compactness, and ability to provide more highly resolved spatiotemporal PM concentrations. However, the PM data from these sensors are often of questionable quality, and the sensors need to be characterized individually for the environmental conditions under which they will be making measurements. In this study, we designed and assessed a cost-effective (∼$700) calibration chamber capable of continuously providing a uniform PM concentration simultaneously to multiple low-cost PM sensors and robust calibration relationships that are independent of sensor position. The chamber was designed and evaluated with a Computational Fluid Dynamics (CFD) model and a rigorous experimental protocol. We then used this new chamber to calibrate 242 Plantower PMS 3003 sensors from two production lots (Batches I and II) with two aerosol types: ammonium nitrate (for Batches I and II) and alumina oxide (for Batch I). Our CFD models and experiments demonstrated that the chamber is capable of providing uniform PM concentration to 8 PM sensors at once within 6% error and with excellent reliability (intraclass correlation coefficient > 0.771). The study identified two malfunctioning sensors and showed that the remaining sensors had high linear correlations with a DustTrak monitor that was calibrated for each aerosol type (R2 > 0.978). Finally, the results revealed statistically significant differences between the responses of Batches I and II sensors to the same aerosol (P-value<0.001) and the Batch I sensors to the two different aerosol types (P-value<0.001). This chamber design and evaluation protocol can provide a useful tool for those interested in systematic laboratory characterization of low-cost PM sensors.

Ambient and laboratory evaluation of a low-cost particulate matter sensor.

Low-cost, light-scattering-based particulate matter (PM) sensors are becoming more widely available and are being increasingly deployed in ambient and indoor environments because of their low cost and ability to provide high spatial and temporal resolution PM information. Researchers have begun to evaluate some of these sensors under laboratory and environmental conditions. In this study, a low-cost, particulate matter sensor (Plantower PMS 1003/3003) used by a community air-quality network is evaluated in a controlled wind-tunnel environment and in the ambient environment during several winter-time, cold-pool events that are associated with high ambient levels of PM. In the wind-tunnel, the PMS sensor performance is compared to two research-grade, light-scattering instruments, and in the ambient tests, the sensor performance is compared to two federal equivalent (one tapered element oscillating microbalance and one beta attenuation monitor) and gravimetric federal reference methods (FEMs/FRMs) as well as one research-grade instrument (GRIMM). The PMS sensor response correlates well with research-grade instruments in the wind-tunnel tests, and its response is linear over the concentration range tested (200-850 µg/m3). In the ambient tests, this PM sensor correlates better with gravimetric methods than previous studies with correlation coefficients of 0.88. However additional measurements under a variety of ambient conditions are needed. Although the PMS sensor correlated as well as the research-grade instrument to the FRM/FEMs in ambient conditions, its response varies with particle properties to a much greater degree than the research-grade instrument. In addition, the PMS sensors overestimate ambient PM concentrations and begin to exhibit a non-linear response when PM2.5 concentrations exceed 40 µg/m3. These results have important implications for communicating results from low-cost sensor networks, and they highlight the importance of using an appropriate correction factor for the target environmental conditions if the user wants to compare the results to FEM/FRMs.

Phenytoin and membrane fluidity in myotonic dystrophy.

Electron spin resonance spectroscopy was used to substantiate the presence of a membrane defect in myotonic erythrocytes. There was increased membrane fluidity and decreased polarity in myotonic membranes. Phenytoin (formerly diphenylhydantoin) "normalizes" fluidity differences in spectra derived from myotonic erythrocytes but has no significant effect on normal spectra. These experiments demonstrate the applicability of biophysical methods to human erythrocyte membranes and support the concept of a membrane defect in myotonic dystrophy that does not have a primary myopathic, neuropathic, or vascular cause.

Inverse effect of chronically elevated blood flow on atherogenesis in miniature swine.

The effect of chronically elevated blood flow on the development of atherosclerosis in miniature swine was studied. Fistulas connecting the right external iliac artery and vein were surgically created in four swine, while three were not fistulated. Pulsed Doppler velocity detection cuffs placed around the abdominal aorta and both iliac arteries of all pigs permitted chronic measurements of blood velocity, blood velocity distributions, and blood flow. All swine were fed an atherogenic diet consisting of 20% beef tallow, 3% cholesterol, and 5% cholic acid for 6 months. This diet elevated the serum cholesterol to values exceeding 500 mg/100 ml. Creation of the arteriovenous fistula (AVF) markedly elevated blood velocity and flow in the abdominal aorta and in the shunted iliac artery. In the shunted animals the aortic blood flow was 42.1 +/- 2.0 ml/sec compared with 17.3 +/- 1.4 ml/sec in the unshunted swine. The velocity distribution pattern across the vessel was also indicative of an elevated wall shear stress. After 6 months, the animals were killed and the arterial vessels examined macroscopically and microscopically for the presence of atherosclerotic lesions. In the shunted pigs, 17 +/- 15% of the lumenal surface was occupied by sudanophilic lesions, whereas 80 +/- 8% of the surface was covered by lesions in the unshunted (control) pigs. From these studies, it is apparent that mechanical factors related to blood flow rates can influence the development of atherosclerotic lesions in swine.

Measurement of blood flow through surgical anastomosis using the radioactive microsphere technique.

Two different radioactive microspheres (141Ce and 46Sc) were used to measure blood flow to an area of the large intestine in dogs before and after a surgical resection was performed with surgical staples. The healing of an anastomosis is theoretically related to the blood flow to the anastomotic site. Blood flow studies were conducted in three dogs using this technique. The average blood flow preoperatively was 0.558 mL/minute per gram and 1.04 mL/minute per gram postoperatively. The standard deviation was +/- 0.16. These results indicate a statistically significant (P less than .05) increase in blood flow at the anastomotic site six days after anastomosis when compared with the blood flow to the same area before any surgical procedures.

Comparison of Maxon suture with Vicryl, chromic catgut, and PDS sutures in fascial closure in rats.

Two hundred ten rats were randomized into one of five study groups to compare standard absorbable sutures with a new synthetic absorbable suture. We evaluated Maxon (polyglyconate), Vicryl (polyglactin), chromic catgut (catgut), and PDS (polydioxanone) with respect to tissue inflammatory reaction, knot security, suture tensile strength, and suture absorption. The results indicate that Maxon and PDS elicited a lower degree of chronic inflammation when compared with Vicryl and chromic catgut. The tensile strengths of Maxon and Vicryl significantly exceeded those of PDS and chromic catgut during the critical period of wound healing. Maxon and PDS retained a larger percentage of tensile strength during the long postoperative period, whereas Vicryl and chromic catgut were mostly absorbed. Maxon is an excellent addition to the armamentarium of the gynecologic surgeon.

Rewarming in immersion hypothermia: radio-wave and inhalation therapy.

Anesthetized random source dogs were cooled by ice water immersion (1 degree C) to a stable core temperature of 25 degrees C, and subsequently rewarmed with warm humidified inhalation (43 degrees C, 450 cc of min ventilation/kg), radio wave induction hyperthermia (4-6 W/kg) or both therapies simultaneously. The mean time required for core rewarming to 30 degrees C was 262 +/- 29 min for humidified ventilation, 68.5 +/- 6 min for radio wave therapy (P less than 0.01), and 74.8 +/- 12 for both therapies combined (P less than 0.3 vs. radio wave). There was no tissue damage with these protocols. These data suggest radio wave heating alone is the most rapid non-invasive method for core rewarming in immersion hypothermia.

A study to investigate the ability of subjects with chronic lung diseases to provide evidential breath samples using the Lion Intoxilyzer 6000 UK breath alcohol testing device.

The Lion Intoximeter 3000 has been used for evidential breath testing in the U.K. for some years. Some individuals with lung diseases have difficulty in providing evidential breath samples using the device. This study describes an investigation that we have carried out on a newer instrument--the Lion Intoxilyzer 6000UK--which is now in use in the U.K. The study was designed to investigate the ability of subjects with a variety of lung diseases to provide evidential breath samples using this device. The 40 adult subjects investigated comprized 10 normal controls, 10 with asthma, 10 with chronic obstructive pulmonary disease (COPD) and 10 with restrictive lung disease. After baseline spirometry, subjects were given alcohol to drink, the quantity based upon body weight. After a gap of at least 20 min, subjects were asked to provide evidential breath samples in accordance with.the test procedure built into the Lion Intoxilyzer 6000UK. The results showed that two asthmatic subjects, four with COPD and three with restrictive lung disease failed to provide evidential breath samples even after four attempts. Despite the device requiring a minimum sample volume of 1.2 l, eight of the nine subjects who failed had a forced vital capacity (FVC) of more than 1.5 l. Seven of these nine subjects had a forced expiratory volume in 1 sec (FEV1) of less than 1.0 l. In conclusion, this study has shown that some subjects with lung diseases may have difficulty in providing evidential breath samples using the Lion Intoxilyzer 6000 UK.

High-performance liquid chromatographic determination of perphenazine and amitriptyline hydrochloride in two-component tablet formulations.

A rapid, precise, and accurate high-performance liquid chromatographic procedure is presented for the simultaneous determination of perphenazine and amitriptyline hydrochloride in two-component tablet formulations. An aliquot of a methanolic extract of the tablet, containing trifluoperazine hydrochloride as an internal standard, is chromatographed on a nitrile bonded phase microparticulate column using a 0.005 M ammonium acetate-methanol (20:80) mobile phase. Quantitation is by peak area. The relative standard deviations for the procedure are 0.34 and 0.54% for the simultaneous determination of perphenazine and amitriptyline, respectively. Eight commercial tablet formulations were analyzed and found to contain 96.5-101.5 and 96.5-103.3% of the labeled amounts of perphenazine and amitriptyline hydrochloride, respectively.

Simultaneous determination of reserpine and hydrochlorothiazide in two-component tablet formulations by high-performance liquid chromatography.

A high-performance liquid chromatographic procedure is presented for the simultaneous determination of reserpine and hydrochlorothiazide in two-component tablet formulations. An aliquot of a tetrahydrofuran extract of the tablet, containing polylythiazide as an internal standard, is chromatographed on a microparticulate silica gel column using a mobile phase of 0.01% (v/v) diethylamine, 5% (v/v) chloroform, and 18% (v/v) 2-propanol in n-hexane. The relative standard deviations are 1.2 and 0.6% for the simultaneous determination of reserpine and hydrochlorothiazide, respectively. Seven commericial tablet formulations were found to contain 92.7--101.0% and 98.3--101.4% of the labeled amounts of reserpine and hydrochlorothiazide, respectively.

Simultaneous determination of procainamide and N-acetylprocainamide in plasma by high-performance liquid chromatography.

A sensitive, specific, high-performance liquid chromatographic procedure is described for the simultaneous determination of procainamide and its metabolite, N-acetylprocainamide, in plasma. Basic plasma (2.0 ml), containing pheniramine maleate as an internal standard, is partitioned with methylene dichloride. The organic extract is concentrated to between 0.3 and 0.5 ml, and 100-microliter aliquots are chromatographed on a microparticulate silica gel column using 0.1% acetic acid-20% 0.1 M ammonium acetate in acetonitrile as the mobile phase. With a fixed-wavelength (254-nm) UV detector, both compounds can be quantitated in the 0.1-8.0-microgram/ml of plasma range.

High-performance liquid chromatographic determination of isoniazid and 1-isonicotinyl-2-lactosylhydrazine in isoniazid tablet formulations.

A high-performance liquid chromatographic procedure is presented for the simultaneous determination of isoniazid and 1-isonicotinyl-2-lactosylhydrazine (I) in isoniazid tablet formulations. An aliquot of a diluted aqueous tablet extract is introduced onto a microparticulate cyanopropyl bonded-phase column using a valve-loop injector and chromatographed using a mobile phase of acetonitrile--0.01 M, pH 3.5 aqueous acetate buffer (5:95). Compound I can be determined at levels as low as 0.5% of the isoniazid label claim. The relative standard deviations are 0.4 and 0.7% for the simultaneous determination of isoniazid and I, respectively. Seven commercial tablet formulations contained 93.8--97.0% of the labeled isoniazid amounts and 0.3--5.8% of I, expressed as equivalent isoniazid relative to the labeled isoniazid level.

Combined assay, identification, and foreign related steroids test for methandrostenolone by high-speed liquid chromatography.

A high-speed liquid chromatographic system is described, which can be used for the simultaneous identification of the anabolic steroid methandrostenolone and its impurities and the quantitation of each of these compounds. Separation is effected by adsorption chromatography on a slurry-packed microparticulate silica gel column.

Simultaneous high-speed liquid chromatographic determination of tetracycline and rolitetracycline in rolitetracycline formulations.

A rapid, precise high-speed liquid chromatographic procedure for the simultaneous determination of tetracycline and rolitetracycline in rolitetracycline formulations is described. Samples are dissolved in water, chilled to 0 degrees, and chromatographed on a pellicular cation-exchange resin, The specificity of this method represents a significant improvement over present analytical procedures, which fail to differentiate between rolitetracycline and its hydrolysis product, tetracycline, in these formulations.

Stability-indicating high-performance liquid chromatographic determination of chlorpropamide, tolbutamide, and their respective sulfonamide degradates.

A quantitative high-performance liquid chromatographic method for the determination of chlorpropamide, tolbutamide, and their respective hydrolysis products, p-chlorobenzenesulfonamide and p-toluenesulfonamide, in solid dosage forms was developed. The method is stability indicating and can be used to determine the sulfonamide hydrolysis product and the intact drug in the presence of minor degradates. Method reproducibility, demonstrated by repeated injections of a calibration standard, was 1.21%. The lower limit of quantitation of the hydrolysis products, p-chlorobenzenesulfonamide and p-toluenesulfonamide, was 0.2 microgram/5-microliter injection. The accuracy of the method for intact drugs was determined by comparison of the HPLC results to those obtained by the appropriate USP or BP assays. The mean of the results obtained by the two methods differed by 0.7% for chlorpropamide and 0.3% for tolbutamide. Pure drug samples were spiked with amounts of the hydrolysis products ranging from 20 to 120% of the intact content. The mean percent recovery for p-chlorobenzenesulfonamide was 98.6%; for p-toluenesulfonamide, it was 100.6%. A qualitative TLC procedure for the detection of chlorpropamide, p-chlorobenzenesulfonamide, dipropylurea, propylurea, n-propylamine, tolbutamide, p-toluenesulfonamide, dibutylurea, butylurea, and n-butylamine is also described.

High-performance liquid chromatographic determination of chlordiazepoxide and major related impurities in pharmaceuticals.

A rapid, precise, forward-phase (adsorption) high-performance liquid chromatographic procedure is presented for the determination of chlordiazepoxide and two common impurities, 7-chloro-1,3-dihydro-5-phenyl-2H-1,4-benzodiazepin-2-one 4-oxide and 2-amino-5-chlorobenzophenone, in commercial formulations and for the determination of the benzophenone in the chlordiazepoxide drug substance. The method involves simultaneous quantitation of chlordiazepoxide and the 1,3-dihhydro impurity, followed by quantitation of the benzophenone from a separate sample extract using a second mobile phase. A single microparticulate silica gel column is used throughout. Nitrazepam and o-dinitrobenzene are the internal standards, Quantitation is by peak area using a computing integrator, except that the peak due to the benzophenone is quantitated by peak height. The described procedure is of equivalent precision, but superior accuracy, to the BP 1973 spectrophotometric procedure for the analysis of chlordiazepoxide in chlordiazepoxide formulations. Quantitation of the 1,3-dihydro and the benzophenone impurities at levels as low as 6.3 and 0.9 ng, respectively, is demonstrated.