NADH-methemoglobin reductase activity: adult versus child

The Nitrate-Nitrite-Nitric Oxide Pathway: Potential Role in Mitigating Oxidative Stress in Hypertensive Disorders of Pregnancy

Hypertensive diseases of pregnancy (HDPs) represent a global clinical challenge, affecting 5-10% of women and leading to complications for both maternal well-being and fetal development. At the heart of these complications is endothelial dysfunction, with oxidative stress emerging as a pivotal causative factor. The reduction in nitric oxide (NO) bioavailability is a vital indicator of this dysfunction, culminating in blood pressure dysregulation. In the therapeutic context, although antihypertensive medications are commonly used, they come with inherent concerns related to maternal-fetal safety, and a percentage of women do not respond to these therapies. Therefore, alternative strategies that directly address the pathophysiology of HDPs are required. This article focuses on the potential of the nitrate-nitrite-NO pathway, abundantly present in dark leafy greens and beetroot, as an alternative approach to treating HDPs. The objective of this review is to discuss the prospective antioxidant role of nitrate. We hope our discussion paves the way for using nitrate to improve endothelial dysfunction and control oxidative stress, offering a potential therapy for managing HDPs.

Skin ulcers as a complication of short-term use of phenazopyridine in an old man: A case report

INTRODUCTION

Phenazopyridine is an azo dye, which exerts local anesthetic or analgesic action on urinary tract mucosa through an unknown mechanism. Besides its common complications including orange discoloration of the urine and gastrointestinal problems, it may have rare side effects like hemolytic anaemia, methemoglobinemia, renal failure, and skin changes. We reported a paraplegic man with skin ulcers on scretom and right foot after about 3 days of phenazopyridine use CASE REPORT: A 62-year-old man presented with flesh shaped deep ulcers in lower parts of the body. He declared that at first a bluish discoloration was developed in the lower extremities and scrotum skin after use of eight phenazopyridine tablets (200 mg) and then these lesions turned to blisters and ulcers and they were prurient. The patient underwent sonography and CT-angiography; however, no pathologic findings were found. He just received losartan for many years as past drug history. According to the history, a delayed drug hypersensitivity reaction was suspected and the patient wounds healed after using special type of dressings and antibiotic therapy regarding positive wound cultures.

CONCLUSION

Phenazopyridine severe skin changes are hardly reported. We described a case who experienced severe skin reactions and ulcers following phenazopyridine use not related to other complications including renal dysfunction, methemoglobinemia, and hemolytic anemia.

Methemoglobinemia: Infants at risk

Methemoglobin is formed when the iron center in hemoglobin is oxidized from ferrous iron to ferric iron. The functional consequence of this change is that hemoglobin is transformed to methemoglobin and cannot oxygenate tissues adequately, causing hypoxia and cyanosis. Infants have unique physiology that increases their risk of developing methemoglobinemia. Infants drink more water per body weight compared to children and adults, have lower NADH cyb5r reductase activity that converts methemoglobin to hemoglobin, and have a higher percentage of fetal hemoglobin, which is easier to convert to methemoglobin. A well-studied exposure to a chemical that can cause methemoglobinemia in infants is nitrate in well water. For the first part specifically about methemoglobin in infants, articles that were recent (2015-now) were given preference over articles that were older. Search terms included: methemoglobin, methemoglobinemia, infant, acquired, congenital, and methylene blue. For the latter half of the paper on nitrate and methemoglobinemia, preference was given to articles that described regionally important cases. In addition, search terms were: Minnesota, methemoglobinemia, nitrate, well water, drinking water, and infant. Acquired methemoglobinemia is rare, yet can still be seen in medical settings, and when an infant is exposed to nitrate in well water above 10 mg/L. To prevent exposure, parents should have their water tested for nitrate before the baby comes home. Physicians should make it practice to ask what the source of drinking water is for newly pregnant women and urge them to test for nitrate and bacteria if using a well. Using bottled water to make formula is also an option, but the best option is still breastfeeding.