Pre-COVID-19 Social Determinants of Health Among Mexican Migrants in Los Angeles and New York City and Their Increased Vulnerability to Unfavorable Health Outcomes During the COVID-19 Pandemic

Journal of Immigrant and Minority Health - COVID-19 has disproportionally affected underrepresented minorities (URM) and low-income immigrants in the United States. The aim of the study is to...     

Multiband compression limiting for hearing-impaired listeners

Four multiband compression limiters and two linear amplification systems were compared in terms of the intelligibility of consonant-vowel-consonant (CVC) nonsense syllables for two hearing-impaired listeners over a 30 dB range of input levels. Each system incorporated one of two frequency-gain characteristics and one of three limiting characteristics (no limiting, moderate limiting, or severe limiting). The subjects were instructed to choose overall listening levels that would permit speech spanning the range of input levels to be as intelligible as possible and comfortable for long-term listening. Relative to linear amplification, the overall gain selected by the subjects increased by roughly 5 and 11 dB for the moderate and severe limiter, respectively. With linear amplification, the maximum score, 82 percent correct, was obtained at the highest input level and scores fell roughly 34 percentage points as input level was reduced. With compression limiting, although the maximum scores, 81 percent and 79 percent correct, were obtained at lower input levels, performance was comparable to that with linear amplification. Also, scores spanned a range of only 22 and 9 percentage points across the range of input levels with the moderate and severe limiter, respectively. This benefit was due to the improved scores provided by compression limiting at the low input levels. However, this advantage was offset somewhat by the disadvantage provided by compression at high input levels relative to linear amplification. Error analysis indicated that the spectral degradations introduced by independent compression of 16 frequency bands may have caused the reduced intelligibility at higher input levels.     

Predicting the solubility of sulfamethoxypyridazine in individual solvents. I: Calculating partial solubility parameters

Sulfamethoxypyridazine, a representative model of a drug molecule, is used to test the extended Hansen method for estimating partial solubility parameters of solid compounds. Solubilities are determined in polar and nonpolar solvents. The method provides reasonable partial parameters for the sulfonamide, and it may be useful in obtaining partial parameters for other drug molecules. A four-parameter extended Hansen approach involving proton donor and acceptor parameters is used in fitting the data to a theoretical model. A term, Wh, is introduced as an empirical measure of solute-solvent interactions due to hydrogen bonding. The use of the empirical term Wh allows the researcher to fit experimental solubilities and thus design regression models and equations which provide a reasonable prediction of solubilities of a polar drug in a number of very different solvents. A Flory-Huggins size correction term improves the prediction of sulfamethoxypyridazine solubilities in these irregular solutions.     

Removal of the endothelial layer in perfused mesenteric vascular bed of the rat.

The endothelial layer was removed from the isolated mesenteric vascular bed of the rat by perfusion with hypotonic Tyrode solution for 12.5 min. This procedure damaged more than 95% of the endothelial cells. After endothelial removal, the response to norepinephrine was significantly enhanced, whereas the relaxation induced by acetylcholine (ACh) was completely abolished. The results of this work show that perfusion with hypotonic solutions provides a reliable method of endothelial removal in isolated perfused vascular beds, allowing the study of endothelial-dependent vascular responses.     

Partial-solubility Parameters of Naproxen and Sodium Diclofenac

The expanded Hansen method was tested for determination of the solubility parameters of two non-steroidal anti-inflammatory drugs, naproxen and sodium diclofenac. This work describes for the first time the application of the method to the sodium salt of a drug. The original dependent variable of the expanded Hansen method, involving the activity coefficient of the drug, was compared with the direct use of the logarithm of the mole fraction solubility lnX₂ in the solubility models. The solubility of both drugs was measured in pure solvents of several chemical classes and the activity coefficient was obtained from the molar heat and the temperature of fusion. Differential scanning calorimetry was performed on the original powder and on the solid phase after equilibration with the pure solvents, enabling detection of possible changes of the thermal properties of the solid phase that might change the value of the activity coefficient. The molar heat and temperature of fusion of sodium diclofenac could not be determined because this drug decomposed near the fusion temperature. The best results for both drugs were obtained with the dependent variable lnX₂ in association with the four-parameter model which includes the acidic and basic partial-solubility parameters δ_a and δ_b instead of the Hansen hydrogen bonding parameter δ_h. Because the dispersion parameter does not vary greatly from one drug to another, the variation of solubility among solvents is largely a result of the dipolar and hydrogen-bonding parameters, a fact that is being consistently found for other drugs of small molecular weight. These results support earlier findings with citric acid and paracetamol that the expanded Hansen approach is suitable for determining partial-solubility parameters. The modification introduced in the expanded Hansen method, i.e. the use of lnX₂ as the dependent variable, provides better results than the activity coefficient used in the original method. This is advantageous for drugs such as sodium diclofenac for which the ideal solubility cannot be estimated. This paper shows for the first time that the method is suitable for determination of the partial-solubility parameters of a sodium salt of a drug, sodium diclofenac.     

A malformed child with a recombinant chromosome 7, rec(7) dup p, derived from a maternal pericentric inversion inv(7)(p15q36).

We report a child with facial dysmorphic features, hypoplasia of the external genitalia, intestinal malrotation, congenital cardiac defect, and minor limb anomalies. Chromosome studies showed a recombinant chromosome 7, rec(7) dup p, resulting from a maternal pericentric inversion inv(7)(p15 q36). Thus, this child had partial trisomy 7p in addition to a small distal monosomy 7. The clinical findings are compared with those found in previous reports of trisomy 7p. Finally, some general principles for genetic counselling are discussed.     

Changes in humoral immune response after SARS-CoV-2 infection in liver transplant recipients compared to immunocompetent patients

The protective capacity and duration of humoral immunity after SARS-CoV-2 infection are not yet understood in solid organ transplant recipients. A prospective multicenter study was performed to evaluate the persistence of anti-nucleocapsid IgG antibodies in liver transplant recipients 6 months after coronavirus disease 2019 (COVID-19) resolution. A total of 71 liver transplant recipients were matched with 71 immunocompetent controls by a propensity score including variables with a well-known prognostic impact in COVID-19. Paired case–control serological data were also available in 62 liver transplant patients and 62 controls at month 3 after COVID-19. Liver transplant recipients showed a lower incidence of anti-nucleocapsid IgG antibodies at 3 months (77.4% vs. 100%, p < .001) and at 6 months (63.4% vs. 90.1%, p < .001). Lower levels of antibodies were also observed in liver transplant patients at 3 (p = .001) and 6 months (p < .001) after COVID-19. In transplant patients, female gender (OR = 13.49, 95% CI: 2.17–83.8), a longer interval since transplantation (OR = 1.19, 95% CI: 1.03–1.36), and therapy with renin–angiotensin–aldosterone system inhibitors (OR = 7.11, 95% CI: 1.47–34.50) were independently associated with persistence of antibodies beyond 6 months after COVID-19. Therefore, as compared with immunocompetent patients, liver transplant recipients show a lower prevalence of anti-SARS-CoV-2 antibodies and more pronounced antibody levels decline.     

Three-dimensional structure of extended chromatin fibers as revealed by tapping-mode scanning force microscopy.

Unfixed chicken erythrocyte chromatin fibers in very low salt have been imaged with a scanning force microscope operating in the tapping mode in air at ambient humidity. These images reveal a three-dimensional organization of the fibers. The planar "zig-zag" conformation is rare, and extended "beads-on-a-string" fibers are seen only in chromatin depleted of histones H1 and H5. Glutaraldehyde fixation reveals very similar structures. Fibers fixed in 10 mM salt appear somewhat more compacted. These results, when compared with modeling studies, suggest that chromatin fibers may exist as irregular three-dimensional arrays of nucleosomes even at low ionic strength.     

The permeability of the microvasculature of the perfused rat testis to small hydrophilic substances

The permeability-surface area products (PS) for sodium, Cr-EDTA, and cyanocobalamine (CoB12) have been determined in isolated perfused rat testes, using the single-passage multiple tracer technique, with albumin as the reference tracer. The validity of using albumin was established from its recovery in the perfusate leaving the testis, which was 98.73+/-0.48% of that for Cr-labeled red cells. The PS values obtained for Na, Cr-EDTA, and CoB12 were correlated with perfusate flow, both below and above levels that were equivalent to normal rates of blood flow in the testis (0.3 mL/[g x min]). The values found at the highest flow rates obtained (between 2.7 and 3.5 mL/[g x min]) were 2230+/-240 microL/(g x min) (n = 8) for sodium, 1460+/-140 microL/(g x min) (n = 7) for Cr-EDTA, and 850+/-80 microL/(g x min) (n = 7) for CoB12. These values are similar to those reported at equivalent flow rates for heart muscle and greater than those reported for skeletal muscle, both of which have unfenestrated capillaries similar to testis, but are less than the values for pancreas and salivary gland, which have fenestrated capillaries and are similar to most other endocrine tissues. However, the permeability coefficients for these markers in the testis (calculated using published values for the surface area of the testicular microvasculature) appear to be considerably greater than for any other tissue studied thus far. By extrapolating extraction values, either linearly or logarithmically, to obtain maximal values for PS for Cr-EDTA and CoB12, and comparing the ratio of these PS area values with the ratio of the diffusion coefficients of these molecules, it can be calculated that the equivalent pore radius for the testicular endothelium is between 5 and 6 nm, comparable to those calculated for other nonfenestrated endothelia.