Assessment of dispersion of airborne particles of oral/nasal fluid by high flow nasal cannula therapy.

BACKGROUND: Nasal High Flow (NHF) therapy delivers flows of heated humidified gases up to 60 LPM (litres per minute) via a nasal cannula. Particles of oral/nasal fluid released by patients undergoing NHF therapy may pose a cross-infection risk, which is a potential concern for treating COVID-19 patients. METHODS: Liquid particles within the exhaled breath of healthy participants were measured with two protocols: (1) high speed camera imaging and counting exhaled particles under high magnification (6 participants) and (2) measuring the deposition of a chemical marker (riboflavin-5-monophosphate) at a distance of 100 and 500 mm on filter papers through which air was drawn (10 participants). The filter papers were assayed with HPLC. Breathing conditions tested included quiet (resting) breathing and vigorous breathing (which here means nasal snorting, voluntary coughing and voluntary sneezing). Unsupported (natural) breathing and NHF at 30 and 60 LPM were compared. RESULTS: Imaging: During quiet breathing, no particles were recorded with unsupported breathing or 30 LPM NHF (detection limit for single particles 33 µm). Particles were detected from 2 of 6 participants at 60 LPM quiet breathing at approximately 10% of the rate caused by unsupported vigorous breathing. Unsupported vigorous breathing released the greatest numbers of particles. Vigorous breathing with NHF at 60 LPM, released half the number of particles compared to vigorous breathing without NHF.Chemical marker tests: No oral/nasal fluid was detected in quiet breathing without NHF (detection limit 0.28 µL/m3). In quiet breathing with NHF at 60 LPM, small quantities were detected in 4 out of 29 quiet breathing tests, not exceeding 17 µL/m3. Vigorous breathing released 200-1000 times more fluid than the quiet breathing with NHF. The quantities detected in vigorous breathing were similar whether using NHF or not. CONCLUSION: During quiet breathing, 60 LPM NHF therapy may cause oral/nasal fluid to be released as particles, at levels of tens of µL per cubic metre of air. Vigorous breathing (snort, cough or sneeze) releases 200 to 1000 times more oral/nasal fluid than quiet breathing (p < 0.001 with both imaging and chemical marker methods). During vigorous breathing, 60 LPM NHF therapy caused no statistically significant difference in the quantity of oral/nasal fluid released compared to unsupported breathing. NHF use does not increase the risk of dispersing infectious aerosols above the risk of unsupported vigorous breathing. Standard infection prevention and control measures should apply when dealing with a patient who has an acute respiratory infection, independent of which, if any, respiratory support is being used. CLINICAL TRIAL REGISTRATION: ACTRN12614000924651.

Antagonistic effect of acetic acid and salt for inactivating Escherichia coli O157:H7 in cucumber puree.

AIM: This study was conducted to investigate the effects of acetic acid alone or combined with salt for inhibiting Escherichia coli O157:H7 in cucumber puree during storage time at 5 and 22 degrees C. METHODS AND RESULTS: Samples at various concentrations were prepared by the addition of acetic acid (0%, 0.25%, 0.5%, 0.75%, 1%, 2%, 2.5%, or 3%) along with NaCl (0% or 3%) and pureed cucumber (50% or 94%). The effect of storage temperature (5 and 22 degrees C) on the survival of E. coli O157:H7 was also tested. The numbers of E. coli O157:H7 were reduced as the amount of acetic acid increased (P < 0.01) and rate of reduction was more rapid at 22 degrees C than at 5 degrees C. Combinations of acetic acid and salt were less effective at killing E. coli O157:H7 in simulated pickled cucumber samples stored at 5 and 22 degrees C than did treatment of acetic acid alone. The concentration of pureed cucumber affected the reduction rate of E. coli O157:H7. When stored at 5 degrees C, E. coli O157:H7 survived for up to 23 days in a mixture of 94% cucumber puree, 1% acetic acid, and 3% NaCl. CONCLUSIONS: There was the antagonistic effect of acetic acid and 3% NaCl with regard to the reduction of E. coli O157:H7. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results suggest that pickled cucumbers prepared with at least 2% acetic acid and stored at room temperature (22 degrees C) after 3 days storage can free from E. coli O157:H7 without heating.

Acute exacerbations of asthma: epidemiology, biology and the exacerbation-prone phenotype.

Asthma is a highly prevalent chronic respiratory disease affecting 300 million people world-wide. A significant fraction of the cost and morbidity of asthma derives from acute care for asthma exacerbations. In the United States alone, there are approximately 15 million outpatient visits, 2 million emergency room visits, and 500,000 hospitalizations each year for management of acute asthma. Common respiratory viruses, especially rhinoviruses, cause the majority of exacerbations in children and adults. Infection of airway epithelial cells with rhinovirus causes the release of pro-inflammatory cytokines and chemokines, as well as recruitment of inflammatory cells, particularly neutrophils, lymphocytes, and eosinophils. The host response to viral infection is likely to influence susceptibility to asthma exacerbation. Having had at least one exacerbation is an important risk factor for recurrent exacerbations suggesting an 'exacerbation-prone' subset of asthmatics. Factors underlying the 'exacerbation-prone' phenotype are incompletely understood but include extrinsic factors: cigarette smoking, medication non-compliance, psychosocial factors, and co-morbidities such as gastroesophageal reflux disease, rhinosinusitis, obesity, and intolerance to non-steroidal anti-inflammatory medications; as well as intrinsic factors such as deficient epithelial cell production of the anti-viral type I interferons (IFN-alpha and IFN-beta). A better understanding of the biologic mechanisms of host susceptibility to recurrent exacerbations will be important for developing more effective preventions and treatments aimed at reducing the significant cost and morbidity associated with this important global health problem.

Evidence of early pyrometallurgy in the kerman range in iran.

Physical and chemical anal ysis of pottery fragments, including a crucible shard and ore samples from Tal-i-Iblis, Iran, suggests that copper smelting may have been well advantced late in the fifth millennium B.C.

Tris(dichloropropyl)phosphate, a mutagenic flame retardant: frequent cocurrence in human seminal plasma.

Negative-chemical-ionization mass spectral screening of extracts of human seminal plasma has revealed a presence of a Cl7 ion cluster at a mass-to-charge ratio (m/z) of 463 in a significant number of the samples examined (34 out of 123). Experiments with different gases used to generate the negative-chemical-ionization plasma indicated that the ion at m/z 463 was a chloride adduca of a Cl6 molecule with a mass of 428 daltons. Negative-chemical-ionization mass measurement with ions from the iodoform mass spectrum used as reference peaks gave a mass of 427.882 daltons; C9H15PCl6 has a molecular weight of 427.883. Extraction of polyurethane foam with toluene produced an extract that consistently gave a negative-chemical-ionization spectrum containing an intense Cl7ion at m/z463. The component producing ion was isolated, and its proton nuclear magnetic resonance spectrum confirmed that it was tris (1,3-dichloro-2-propyl)phosphate, a mutagenic flame retardant. The negative-chemical-ionization screening evidence suggests that this flame retardant or its isomer tris(2,3-dichloro-l-propyl)phosphate, or both, are absorbved into the body from formulations in which they are used as flame retardants. Remedial action seems indicated to reduce human exposure to these compunds.

Children absorb tris-BP flame retardant from sleepwear: urine contains the mutagenic metabolite, 2,3-dibromopropanol.

The flame retardant, tris(2,3-dibromopropyl)phosphate (tris-BP), which is a mutagen and causes cancer and sterility in animals is absorbed from fabric by people. 2,3-Dibromopropanol, a metboloite of tris-BP and a mutagen itself, has been found in the urine samples of ten children who were wearing or who had worn tris-BP-treated sleepwear. Eight of these children were wearing well-washed sleepwear and the possibility of absorption of tris-BP from well-washed sleepwear discussed. 2,3-Dibromopropanol was not found in the urines of one child and one adult who had never worn tris-BP-treated garments.

Perceived speed of colored stimuli.

The influence of contrast and color on perceived motion was measured using a speed-matching task. Observers adjusted the speed of an L cone contrast pattern to match that of a variety of colored test patterns. The dependence of speed on test contrast was the same for all test colors measured, differing only by a sensitivity factor. This result suggests that the reduced apparent speed of low contrast targets and certain colored targets is caused by a common cortical mechanism. The cone contrast levels that equate perceived speed differ substantially from those that equate visibility. This result suggests that the neural mechanisms governing speed perception and visibility differ. Perceived speed differences caused by variations in color can be explained by color responses that are characteristic of motion-selective cortex.

Inhibition of c-Jun N-terminal kinase 2 expression suppresses growth and induces apoptosis of human tumor cells in a p53-dependent manner.

c-Jun N-terminal kinase (JNK) plays a critical role in coordinating the cellular response to stress and has been implicated in regulating cell growth and transformation. To investigate the growth-regulatory functions of JNK1 and JNK2, we used specific antisense oligonucleotides (AS) to inhibit their expression. A survey of several human tumor cell lines revealed that JNKAS treatment markedly inhibited the growth of cells with mutant p53 status but not that of cells with normal p53 function. To further examine the influence of p53 on cell sensitivity to JNKAS treatment, we compared the responsiveness of RKO, MCF-7, and HCT116 cells with normal p53 function to that of RKO E6, MCF-7 E6, and HCT116 p53(-/-), which were rendered p53 deficient by different methods. Inhibition of JNK2 (and to a lesser extent JNK1) expression dramatically reduced the growth of p53-deficient cells but not that of their normal counterparts. JNK2AS-induced growth inhibition was correlated with significant apoptosis. JNK2AS treatment induced the expression of the cyclin-dependent kinase inhibitor p21(Cip1/Waf1) in parental MCF-7, RKO, and HCT116 cells but not in the p53-deficient derivatives. That p21(Cip1/Waf1) expression contributes to the survival of JNK2AS-treated cells was supported by additional experiments demonstrating that p21(Cip1/Waf1) deficiency in HCT116 cells also results in heightened sensitivity to JNKAS treatment. Our results indicate that perturbation of JNK2 expression adversely affects the growth of otherwise nonstressed cells. p53 and its downstream effector p21(Cip1/Waf1) are important in counteracting these detrimental effects and promoting cell survival.

Induction of tumors in Syrian hamsters by a human renal papovavirus, RF strain.

Injection of RF virus (RFV), a papovavirus isolated from human urine, into newborn Syrian hamsters induced subcutaneous sarcomas in 50% of the recipients with 18- to 48-week latent periods. Transplantation of 2 X 10(6) primary RFV-induced tumor cells into weaning hamsters caused tumors in 100% of the recipients within 1-2 weeks. Continuous tissue culture cell lines were established from two primary tumors; one of these was transplantable. An in vitro-transformed continuous cell line (RF-194) obtained by infection of primary hamster embryo fibroblasts with RFV was transplantable in weaning hamsters. Neither infectious RFV nor virion antigens were detected in transformed cells. No RFV was recovered when transformed cells were fused with permissive, human embryo kidney cells by means of inactivated Sendai virus. Immunoperoxidase staining was used to show that all three RFV-transformed cell lines contained an intranuclear T-antigen closely similar to that of simian virus 40(SV40)-infected cells. Most hamsters (84%) with primary or transplanted RFV tumors responded with antibodies that reacted with RFV T-antigen and the T-antigen of SV40-infected cells. Likewise, hamster antisera against SV40 T-antigen cross-reacted with RFV T-antigen. Adsorption of RFV T-antisera with an excess of lyophilized SV40-transformed cells removed all detectable activity against SV40 T-antigen but left significant activity against RFV T-antigen. The reciprocal adsorption produced an antiserum spedicic for SV40 T-antigen. Thus human and simian papovavirus T-antigens were related but immunologically separable.

Contact transmission of avian leukosis virus.

Intravenous inoculation of four age groups of White Leghorn chicks with ALV-F42, a group A field strain of avian leukosis virus (ALV), indicated that persistent tolerant infection could be induced as late as 2 weeks post hatch, though most birds responded with neutralizing antibody. Contact infection by environmental exposure to ALV was 100% effective in newly hatched and 28-day-old chicks. All contact-infected birds responded immunologically after transient viremia. A follow-up of immune birds from these six groups demonstrated that active multiplication of ALV continued despite neutralizing antibody. Infectious virus was shed by oral and cloacal routes, as well as through vertical transmission by hens to their embryos. Up to 10(8) infectious units of virus/g of feces was shed by 12-day-old viremic birds, and to a lesser extent virus was also shed in saliva as measured by oral washing. The cycle of contact transmission was also evaluated by the assessment of the efficacy of four portals of entry, where exposed skin was most effective in permitting infection, followed by oral, nasal, and conjunctival routes.

The maturation of form and motion perception in school age children.

The purpose of the current study was to investigate the maturation of form and motion perception, specifically the component visual abilities involved in the identification of motion-defined form, in children ranging in age from 3 to 12 years. Experiment 1 compared the maturation of motion-defined and texture-defined shape identification. Minimum speed thresholds on the motion-defined shape task decreased until age 7 years. Orientation difference thresholds on the texture-defined shape task decreased until age 11 years. Experiment 2 compared the maturation of global motion and global texture direction discrimination. Coherence thresholds on both tasks were similar in children of all ages and adults. Experiment 3 compared the maturation of direction discrimination on motion coherence and motion displacement tasks. Maximum displacement thresholds (Dmax) increased until age 7 years. The results are discussed with respect to the maturation of M/dorsal and P/ventral visual pathways.

Recombinant bovine GM-CSF primes superoxide production but not degranulation induced by recombinant bovine interleukin-1 beta in bovine neutrophils.

Bovine neutrophil activation, superoxide production, and beta-glucosaminadase release induced by various biological stimuli were examined. Platelet-activating factor (PAF) and recombinant bovine interleukin-1 beta (r-BoIL-1 beta) induced superoxide production and beta-glucosaminadase release in bovine neutrophils. When these two responses were compared, the dose requirement for maximum activation was similar for PAF (1 x 10(-6) M). However, the concentration of r-BoIL-1 beta required for the maximum degranulation (2.5 x 10(-7) M) was 100-fold higher than that for the maximum superoxide production (2.5 x 10(-9) M). Furthermore, pretreatment of cells with recombinant bovine granulocyte-macrophage colony-stimulating factor (r-BoGM-CSF) enhanced both superoxide production and beta-glucosaminidase release induced by PAF. In contrast, whereas superoxide production induced by r-BoIL-1 beta was enhanced by r-BoGM-CSF priming, beta-glucosaminidase release induced by r-BoIL-1 beta was significantly reduced by pretreatment with r-BoGM-CSF. CL 184,005, a PAF antagonist, inhibited PAF-induced glucosaminidase release and superoxide production but did not inhibit r-BoIL-1 beta-induced superoxide production and degranulation. In addition, it did not inhibit the priming effect of r-BoGM-CSF on r-BoIL-1 beta-induced superoxide production. These results suggest that (1) PAF and r-BoIL-1 beta activate bovine neutrophils by different mechanisms, (2) r-BoGM-CSF primes superoxide production and degranulation induced by PAF, (3) r-BoGM-CSF primes superoxide production but not degranulation induced by r-BoIL-1 beta, and (4) the priming effect of r-BoGM-CSF is not mediated by PAF.

Reduction of blood pressure associated with dietary polyunsaturated fat.

Evidence linking the beneficial effect of dietary polyunsaturated fat on systolic and distolic blood pressure is reported. Under controlled dietary conditions, i.e., when the polyunsaturated fat to saturate fat ratio (P/S) is maintained at about 1.0, with fat providing 25% of total energy intake, blood pressure is significantly lowered in healthy males and females in the 40- to 60-year age group. The subjects selected for these studies were either normotensive or mildly hypertensive. When the subjects resumed their usual diets, their blood pressures reverted to baseline values. Body weights of the subjects remained relatively constant in these studies, and sodium chloride intakes averaged 8 to 12 g per day. It is suggested that the lowering of blood pressure by dietary linoleic acid is mediated through prostaglandins.

Lack of effect of linoleic acid on the high-density-lipoprotein-cholesterol fraction of plasma lipoproteins.

Low-fat, natural diets were fed to 11 middle-aged, healthy male subjects for two 40-d periods to determine effects on plasma lipoproteins. The diets were designed to maintain saturated and monounsaturated fatty acids at 10 en% and linoleic acid (LA) at 3.8 and 10.8 en%. When compared with baseline concentrations, total cholesterol decreased 10% at the end of the lower LA diet and 15% at the end of the higher LA diet. Low-density-lipoprotein cholesterol (LDL-C) decreased 18% and 22%, respectively, during the same periods. Plasma high-density-lipoprotein cholesterol (HDL-C) at the end of each dietary period was not significantly different but the midpoint values were lower by 12.5% on the lower LA diet and 7.3% on the higher LA diet. Apolipoprotein B decreased 27% at the end of the lower LA diet and 37% at the end of the higher LA diet whereas apolipoprotein A-I increased 18% and 24%, respectively. HDL-C was not reduced by dietary LA over a 6-wk period.

Lipid and phospholipid fatty acid composition of plasma, red blood cells, and platelets and how they are affected by dietary lipids: a study of normal subjects from Italy, Finland, and the USA.

A pilot study was conducted of males 40-45 years old from rural areas of three countries to study the long-term effects of dietary fats on the lipids of plasma, red blood cells (RBCs), and platelets. Differences were observed in cholesterol and phospholipid levels of plasma. Total phospholipids of RBCs and platelets were similar in all three countries. The pattern of individual phospholipids of RBCs in the Finnish and Italian samples differed from the American samples. In all plasma and RBC glycerolphospholipids, the monounsaturated fatty acids were highest in the Italian and the saturated fatty acids were highest in the Finnish samples; PUFAs were highest in the USA samples. Platelet glycerolphospholipids followed similar fatty acid patterns. We concluded that the fatty acid compositions of the glycerolphospholipids of plasma, RBCs, and platelets reflect the major dietary fatty acids.

Nutrient content of the diet when the fat is reduced.

When the fat content of the typical US diet was reduced from 40 to 44% of total energy (en %) to approximately 25 en % there was a marked improvement in the overall nutrient content of the diet. Cholesterol, saturated fatty acid, and monounsaturated fatty acid intake were decreased and the polyunsaturated fatty acid content was moderately increased. This kind of dietary change was achieved without changing the usual intake of meats, dairy products, fish, and eggs. As the amount of fat was decreased, carbohydrates in the form of grains, fruits, and vegetables were increased, providing an improvement in the vitamin and mineral content of the diet. Vitamin C, thiamin, riboflavin, niacin, B-6, B-12, and folates increased in the 25 en % diet. Potassium, calcium, magnesium, phosphorus, iron, zinc, and copper intake also increased when the dietary fat decreased.

Dietary stearic acid and thromboxane-prostacyclin biosynthesis in normal human subjects.

Ten male subjects were fed a diet rich in stearic acid while they were contained to a metabolic ward. There were three study periods: a 20-d baseline period followed by two 40-d intervention periods. The baseline diet contained 4.4% of energy from stearic acid; one intervention diet was high in stearic acid (7.3% of energy) and the other intervention diet was low in stearic acid (1.6% of energy). The energy contribution of protein, carbohydrate, and fat (16%, 54%, and 30%, respectively) was identical for the two diets. The fat content was distributed equally among saturated, monounsaturated, and polyunsaturated fatty acids. Urinary excretions of thromboxane B2, 2,3-dinor-thromboxane B2, 6-oxo-prostaglandin F1 alpha, and 2,3-dinor-6-oxo-prostaglandin F1 alpha were not significantly different during the two different intervention periods. This suggests that changes in dietary stearic acid do not affect in vivo thromboxane A2 or prostacyclin biosynthesis.

Effects of diets containing high or low amounts of stearic acid on plasma lipoprotein fractions and fecal fatty acid excretion of men.

Ten middle-aged males participated in a crossover study to determine the cholesterolemic effect of high amounts of stearic acid in a natural diet. They consumed a 20-d stabilization diet followed by two 40-d intervention diets containing either 1.5% of energy as stearic (18:0) acid and 7.3% of energy as palmitic (16:0) acid (low stearate: LS) or 2.4% of energy as 16:0 and 7.3% of energy as 18:0 (high stearate: HS). The experimental diets also contained approximately 10% of energy each as saturated and monounsaturated fatty acids and 7.2-8% of energy as polyunsaturated fatty acids. The primary source of 18:0 in the HS diet was sheanut oil (commercially referred to as shea butter) and palm oil and butter in the LS diet. Plasma total, low-density-lipoprotein, and high-density-lipoprotein cholesterol were significantly lower with the HS than with the LS diet. Total fecal fatty acid excretion was higher throughout the HS period. Apparent digestibility of the major dietary fatty acids showed that all of the selected fatty acids, except 18:0, were > or = 95% absorbed. These data demonstrate that feeding diets containing about two times the usual amount of stearic acid consumed in the United States, contributed to an increase in plasma lipoprotein concentrations at 40 d from an earlier decrease at 20 d. The time required to achieve stable cholesterol concentrations appears to vary depending on the kind of saturated fatty acids present in the diet.

Platelet aggregation in humans is affected by replacement of dietary linoleic acid with oleic acid.

The effect of concentrations of linoleic acid (LA) on platelet aggregation was measured in seven healthy adult males. Subjects were randomly divided into two groups; these groups were fed natural food diets of identical composition except that one was high in LA (11.5% of energy) and low in oleic acid (OA) (7.4% of energy), the other was low in LA (4.5% of energy) and high in OA (15.7% of energy). The thresholds of ADP- and collagen-induced platelet aggregation were increased significantly by the high LA diet even though the intake of total fat and saturated fatty acids did not differ in these diets.

Dietary modification of omega 6 fatty acid intake and its effect on urinary eicosanoid excretion.

A group of women were fed two separate diets in a crossover study and urinary eicosanoids were quantified. One diet contained 3.1% of total energy (en%) as polyunsaturated fatty acids (3.0 en% linoleic acid) and the other contained 8.4 en% polyunsaturated fatty acids (8.3 en% linoleic acid). Carbohydrate replaced fat in the low-polyunsaturated-fat diet. No changes were observed in the urinary excretion of 6-oxo-prostaglandin F1 alpha, its 2,3-dinor metabolite or thromboxane B2 by subjects on either of the diets. Urinary 2,3-dinor-thromboxane B2 excretion was lower (206.5 ng/24 h) when subjects were fed the high-omega 6 polyunsaturated fatty acid diet when compared with the lower-omega 6 polyunsaturated fatty acid diet (275.3 ng/24 h). Conversely, urinary prostaglandin E2 was higher (139.2 ng/g creatinine) during the higher-omega 6 polyunsaturated fatty acid diet when compared with the lower-omega 6 polyunsaturated fatty acid diet (94.4 ng/g creatinine).