Transient neonatal zinc deficiency

Unique presentation of transient zinc deficiency from low maternal breast milk zinc levels

We report full-term siblings with a unique clinical presentation of polycyclic papulosquamous plaques secondary to transient zinc deficiency due to low maternal breast milk zinc levels. We present this case to highlight this unique presentation of zinc deficiency in breastfed infants.

ABM Clinical Protocol #29: Iron, Zinc, and Vitamin D Supplementation During Breastfeeding

A central goal of The Academy of Breastfeeding Medicine is the development of clinical protocols, free from commercial interest or influence, for managing common medical problems that may impact breastfeeding success. These protocols serve only as guidelines for the care of breastfeeding mothers and infants and do not delineate an exclusive course of treatment or serve as standards of medical care. Variations in treatment may be appropriate according to the needs of an individual patient.

Heterodimerization, altered subcellular localization, and function of multiple zinc transporters in viable cells using bimolecular fluorescence complementation

Zinc plays a crucial role in numerous key physiological functions. Zinc transporters (ZnTs) mediate zinc efflux and compartmentalization in intracellular organelles; thus, ZnTs play a central role in zinc homeostasis. We have recently shown the in situ dimerization and function of multiple normal and mutant ZnTs using bimolecular fluorescence complementation (BiFC). Prompted by these findings, we here uncovered the heterodimerization, altered subcellular localization, and function of multiple ZnTs in live cells using this sensitive BiFC technique. We show that ZnT1, -2, -3, and -4 form stable heterodimers at distinct intracellular compartments, some of which are completely different from their homodimer localization. Specifically, unlike the plasma membrane (PM) localization of ZnT1 homodimers, ZnT1-ZnT3 heterodimers localized at intracellular vesicles. Furthermore, upon heterodimerization with ZnT1, the zinc transporters ZnT2 and ZnT4 surprisingly localized at the PM, as opposed to their vesicular homodimer localization. We further demonstrate the deleterious effect that the G87R-ZnT2 mutation, associated with transient neonatal zinc deficiency, has on ZnT1, ZnT3, and ZnT4 upon heterodimerization. The functionality of the various ZnTs was assessed by the dual BiFC-Zinquin assay. We also undertook a novel transfection competition assay with ZnT cDNAs to confirm that the driving force for heterodimer formation is the core structure of ZnTs and not the BiFC tags. These findings uncover a novel network of homo- and heterodimers of ZnTs with distinct subcellular localizations and function, hence highlighting their possible role in zinc homeostasis under physiological and pathological conditions.

Compound heterozygous mutations in SLC30A2/ZnT2 results in low milk zinc concentrations: a novel mechanism for zinc deficiency in a breast-fed infant

Zinc concentrations in breast milk are considerably higher than those of the maternal serum, to meet the infant's requirements for normal growth and development. Thus, effective mechanisms ensuring secretion of large amounts of zinc into the milk operate in mammary epithelial cells during lactation. ZnT2 was recently found to play an essential role in the secretion of zinc into milk. Heterozygous mutations of human ZnT2 (hZnT2), including H54R and G87R, in mothers result in low (>75% reduction) secretion of zinc into the breast milk, and infants fed on the milk develop transient neonatal zinc deficiency. We identified two novel missense mutations in the SLC30A2/ZnT2 gene in a Japanese mother with low milk zinc concentrations (>90% reduction) whose infant developed severe zinc deficiency; a T to C transition (c.454T>C) at exon 4, which substitutes a tryptophan residue with an arginine residue (W152R), and a C to T transition (c.887C>T) at exon 7, which substitutes a serine residue with a leucine residue (S296L). Biochemical characterization using zinc-sensitive DT40 cells indicated that the W152R mutation abolished the abilities to transport zinc and to form a dimer complex, indicating a loss-of-function mutation. The S296L mutation retained both abilities but was extremely destabilized. The two mutations were found on different alleles, indicating that the genotype of the mother with low milk zinc was compound heterozygous. These results show novel compound heterozygous mutations in the SLC30A2/ZnT2 gene causing zinc deficiency in a breast-fed infant.

Guaiazulene: a new treatment option for recalcitrant diaper dermatitis in NICU patients

AIM

Based on a maternal observation, we aimed to evaluate the treatment effectiveness of guaiazulene (GA) containing local pomade in the high-risk neonates with recalcitrant diaper dermatitis (RDD).

METHODS

We included 30 NICU patients of RDD, with level II-III aged between 22 and 67 days. Study group patients (n = 20) were treated with GA containing local pomade (0.05 g/100 g). Control group consisted of patients who had extended antifungal treatment. A visual scale was used to assess the response to treatment at the end of a week. Scoring was done at the beginning of the treatment, on the first, third and seventh days.

RESULTS

Statistically significant differences in visual scores were determined between the two groups at the initial and following days of the treatment. In study group, improvements at the first and third days of the treatment were better than those of control group. Additionally, complete recovery rate in study group was better than that in controls.

CONCLUSION

Having beneficial but no adverse effects, GA containing local pomade provided rapid recovery in risky neonates with RDD, who required rapid improvement.

Functional analysis of two single nucleotide polymorphisms in SLC30A2 (ZnT2): implications for mammary gland function and breast disease in women

Zinc transporter 2 (ZnT2) plays a major role in zinc (Zn) export from the mammary gland. Recently, we determined that ZnT2 is associated with secretory vesicles reflecting its role in Zn secretion during lactation. Herein, we identified two distinct single nucleotide polymorphisms (SNPs) in SLC30A2, which encodes ZnT2. SNP1 (rs35235055) results in a leucine-to-proline substitution (Leu(23)Pro), while SNP2 (rs35623192) results in an arginine-to-cysteine substitution (Arg(340)Cys). We examined the localization and function of each SNP in cells generated to express these polymorphic variants. SNP1 was mislocalized to lysosomes, while SNP2 was mislocalized to the Golgi apparatus. FluoZin-3 fluorescence illustrated increased lysosomal accumulation of Zn in cells expressing SNP1 concomitant with the abrogation of Zn secretion. In contrast, ectopic expression of SNP2 was associated with the expansion of cytoplasmic Zn pools, elevated reactive oxygen species, and increased Zn efflux. Taken together, our data indicate that polymorphic variants in ZnT2 distinctly alter mammary cell Zn metabolism. We speculate that these SNPs may compromise mammary cell function, which may have important implications in human health and breast disease.

Clinical zinc deficiency during adequate enteral nutrition

Deficiency of zinc (Zn), resulting in characteristic skin changes resembling those seen in acrodermatitis enteropathica, has been reported in patients on total parenteral nutrition, but rarely in patients on long-term enteral feeding. Reported here is a patient who developed characteristic skin changes while he was receiving what was considered to be a balanced liquid enteral diet. The skin rash resolved with Zn supplementation.

Evidence that adverse effects of zinc deficiency on essential fatty acid composition in rats are independent of food intake

1. Young male rats were fed on diets containing 3.4, 36 or 411 mg zinc/kg for 10 weeks in order to determine whether effects of Zn deficiency on plasma and liver essential fatty acid composition could be distinguished from those of reduced protein and energy intake. 2. Fatty acid analysis revealed that a Zn intake of 3.4 mg/kg (plasma Zn 0.80 v. 1.97 mmol/l in controls fed on 36 mg Zn/kg) resulted in a significant increase in the linoleic acid:arachidonic acid ratio in both plasma and liver phospholipids in comparison with rats fed on 36 or 411 mg Zn/kg. 3. Zn supplementation (411 mg/kg) decreased the linoleic acid:arachidonic acid ratio in plasma phosphatidylserine compared with that of the controls. 4. The previously reported increase in arachidonic acid (mol %) in liver triacylglycerol of Zn-deficient rats was shown to be a function of a reduced liver triacylglycerol pool size; quantitatively, triacylglycerol content of arachidonic acid in the liver was not significantly affected by Zn intake.

[Trace elements in artificial nutrition. Art and practice]

The trace elements known to be necessary for man are iron, zinc, copper, selenium, chromium, manganese, molybdenum, cobalt and iodine. This review article, which excludes iron, deals with the need for supplemental trace elements during artificial feeding, and the way they should be administered. The biological importance of these trace elements is argued on the basis of their biochemical involvement and the clinical pictures seen in accidental or experimental deficiency states. Assessing a patient's trace element status is rather difficult. The relative merits of different laboratory investigations is discussed: plasma, erythrocyte, capillary and urinary levels, specific enzyme activities, loading tests. The different situations when trace elements are required, assessing the amount needed and the possible toxic risks, are presented from a literature survey.