Methemoglobinemia: A Review and Recommendations for Management

Although the first reports linking mineral nutrition of crops to their quality date back to the 1970s, the effects of mineral nutrition on crop quality had not received the attention they deserved until the 2000s. In crop science, the concept of quality has a broad scope, and depending on the crop species as well as the intended use, different sets of physical and chemical parameters may be considered the most important components of overall quality. This chapter summarizes our current understanding of how mineral nutrition influences the technical (i.e., processing), sensory, and nutritional quality of crop plants and discusses the state-of-the-art advances in mineral nutrition aimed at improved sustainability, food safety, and nutrition security through improved crop quality. Considering both the actual and hidden hunger problems globally, the challenges imposed by climate change and other environmental issues, and the increasing awareness of the importance of nutrition for good health, research on mineral nutrition of crops is focusing on developing sustainable methods for simultaneously increasing productivity, profitability, and quality. However, the mineral nutrient requirements to achieve maximum yield may not always coincide with those to attain the best quality; similarly, higher quality does not always automatically translate into higher economic value.

Sulfhemoglobinemia is an incurable disease caused by an overdose of sulfur-containing drugs with oxidizing properties. Its diagnosis remains hindered due to the similarity of symptoms to other pathological state – methemoglobinemia, as well as contradictory information on the structure and characteristics of sulfhemoglobin. Herein, we present sulfhemoglobinemia model on living functional human erythrocytes, designed to recreate processes which could take place in a patient body in order to complement missing information and highlight distinctiveness of two hemoglobin (Hb) adducts formed after interaction with sulfur donors. Employed techniques, UV–Vis absorption, Raman, Fourier transformed infrared (FT–IR) and electronic circular dichroism (ECD) spectroscopies, allowed to distinguish and characterize Hb adduct with sulfur atom bounded directly to the iron ion (HbFe^III–SH), and irreversibly connected to the porphyrin ring (SHb – sulfhemoglobin). Presented herein results provided also new evidence on formation of both these hemoglobin adducts inside functional erythrocytes under oxidative conditions and during sulfur-containing drug presence, what can be further translated into future physiological studies. Moreover, we found that sulfur attachment to the porphyrin ring altered Hb structure and lead to changes in protein packing inside RBCs, eventually. Interestingly, measurement of blood drop smear by Raman spectroscopy occurred the most accurate method to differentiate HbFe^III–SH and SHb, indicating potential of this technique in sulfhemoglobinemia diagnosis.

Methemoglobinemia is the result of inappropriate oxidation of hemoglobin iron groups, leading to a failure of oxygen transport and delivery, resulting in a clinical state of refractory hypoxia. Methemoglobin levels above 70% are often considered fatal. Acquired methemoglobinemia can be caused by a variety of substances, including sodium nitrite, a commercially available food preservative and color fixative. This report describes a patient presenting with a methemoglobin level of 83% secondary to intentional sodium nitrite ingestion. The methemoglobin level recorded is amongst some of the highest found in surviving patients.