Browsing by Subject "Ascorbic acid"

Now showing 1 - 3 of 3
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    Dispensability of Ascorbic Acid Uptake and Utilization Encoded by ulaABCD for the Virulence of Haemophilus ducreyi in Humans
    (Oxford University Press, 2023) Brothwell, Julie A.; Fortney, Kate R.; Batteiger, Teresa; Katz, Barry P.; Spinola, Stanley M.; Microbiology and Immunology, School of Medicine
    Compared with wounded skin, ascorbic acid is enriched in pustules of humans experimentally infected with Haemophilus ducreyi. Compared with the broth-grown inocula, transcription of the H. ducreyi ulaABCD operon, which encodes genes for ascorbic acid uptake, is increased in pustules. We hypothesized that ascorbic acid uptake plays a role in H. ducreyi virulence. Five volunteers were infected with both H. ducreyi strain 35000HP and its isogenic ulaABCD deletion mutant at multiple sites; the papule and pustule formation rates of the mutant and parent strains were similar. Thus, ascorbic acid uptake is not essential for H. ducreyi virulence in humans.
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    Effect of Vitamin C Supplementation for Pregnant Smokers on Offspring Airway Function and Wheeze at Age 5 Years: Follow-up of a Randomized Clinical Trial
    (American Medical Association, 2023) McEvoy, Cindy T.; Shorey-Kendrick, Lyndsey E.; Milner, Kristin; Harris, Julia; Vuylsteke, Brittany; Cunningham, Michelle; Tiller, Christina; Stewart, Jaclene; Schilling, Diane; Brownsberger, Julie; Titus, Hope; MacDonald, Kelvin D.; Gonzales, David; Vu, Annette; Park, Byung S.; Spindel, Eliot R.; Morris, Cynthia D.; Tepper, Robert S.; Pediatrics, School of Medicine
    Importance: Vitamin C supplementation (500 mg/d) for pregnant smokers has been reported to increase offspring airway function as measured by forced expiratory flow (FEF) through age 12 months; however, its effects on airway function at age 5 years remain to be assessed. Objective: To assess whether vitamin C supplementation in pregnant smokers is associated with increased and/or improved airway function in their offspring at age 5 years and whether vitamin C decreases the occurrence of wheeze. Design, setting, and participants: This study followed up the Vitamin C to Decrease the Effects of Smoking in Pregnancy on Infant Lung Function (VCSIP) double-blind, placebo-controlled randomized clinical trial conducted at 3 centers in the US (in Oregon, Washington, and Indiana) between 2012 and 2016. Investigators and participants remain unaware of the treatment assignments. Forced expiratory flow measurements at age 5 years were completed from 2018 to 2021. Interventions: Pregnant smokers were randomized to vitamin C (500 mg/d) or placebo treatment. Main outcomes and measures: The primary outcome was the prespecified measurement of FEF between 25% and 75% expired volume (FEF25-75) by spirometry at age 5 years. Secondary outcomes included FEF measurements at 50% and 75% of expiration (FEF50 and FEF75), forced expiratory volume in 1 second (FEV1), and occurrence of wheeze. Results: Of the 251 pregnant smokers included in this study, 125 (49.8%) were randomized to vitamin C and 126 (50.2%) were randomized to placebo. Of 213 children from the VCSIP trial who were reconsented into this follow-up study, 192 (90.1%) had successful FEF measurements at age 5 years; 212 (99.5%) were included in the analysis of wheeze. Analysis of covariance demonstrated that offspring of pregnant smokers allocated to vitamin C compared with placebo had 17.2% significantly higher mean (SE) measurements of FEF25-75 at age 5 years (1.45 [0.04] vs 1.24 [0.04] L/s; adjusted mean difference, 0.21 [95% CI, 0.13-0.30]; P < .001). Mean (SE) measurements were also significantly increased by 14.1% for FEF50 (1.59 [0.04] vs 1.39 [0.04] L/s; adjusted mean difference, 0.20 [95% CI, 0.11-0.30]; P < .001), 25.9% for FEF75 (0.79 [0.02] vs 0.63 [0.02] L/s; 0.16 [95% CI, 0.11-0.22]; P < .001), and 4.4% for FEV1 (1.13 [0.02] vs 1.09 [0.02] L; 0.05 [95% CI, 0.01-0.09]; P = .02). In addition, offspring of pregnant smokers randomized to vitamin C had significantly decreased wheeze (28.3% vs 47.2%; estimated odds ratio, 0.41 [95% CI, 0.23-0.74]; P = .003). Conclusions and relevance: In this follow-up study of offspring of pregnant smokers randomized to vitamin C vs placebo, vitamin C supplementation during pregnancy resulted in significantly increased airway function of offspring at age 5 years and significantly decreased the occurrence of wheeze. These findings suggest that vitamin C supplementation for pregnant smokers may decrease the effects of smoking in pregnancy on childhood airway function and respiratory health.
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    Phenazopyridine-Induced Methemoglobinemia in a Jehovah's Witness Treated with High-Dose Ascorbic Acid Due to Methylene Blue Contradictions: A Case Report and Review of the Literature
    (MDPI, 2023-05-24) Menakuru, Sasmith R.; Dhillon, Vijaypal S.; Atta, Mona; Mann, Keeret; Salih, Ahmed; Medicine, School of Medicine
    Methemoglobinemia is an acute medical emergency that requires prompt correction. Physicians should have a high degree of suspicion of methemoglobinemia in cases that present with hypoxemia that does not resolve with supplemental oxygenation, and they should confirm this suspicion with a positive methemoglobin concentration on arterial blood gas. There are multiple medications that can induce methemoglobinemia, such as local anesthetics, antimalarials, and dapsone. Phenazopyridine is an azo dye used over-the-counter as a urinary analgesic for women with urinary tract infections, and it has also been implicated in causing methemoglobinemia. The preferred treatment of methemoglobinemia is methylene blue, but its use is contraindicated for patients with glucose-6-phosphatase deficiency or those who take serotonergic drugs. Alternative treatments include high-dose ascorbic acid, exchange transfusion therapy, and hyperbaric oxygenation. The authors report a case of a 39-year-old female who took phenazopyridine for 2 weeks to treat dysuria from a urinary tract infection and subsequently developed methemoglobinemia. The patient had contraindications for the use of methylene blue and was therefore treated with high-dose ascorbic acid. The authors hope that this interesting case promotes further research into the utilization of high-dose ascorbic acid for managing methemoglobinemia in patients who are unable to receive methylene blue.