Excessive sodium supplementation but not fluid load is correlated with overall morbidity in extremely low birth weight infants.

Objectives: Sodium homeostasis in extremely low birth weight (ELBW) infants is critical. While a lack of sodium delays growth, excessive supplementation increases morbidity. Methods: We performed a single-center retrospective study on sodium and fluid management during the first 2 weeks of live including all ELBW infants born between June 1, 2017 and May 31, 2019. Results: Forty-seven patients (median GA 26 + 6 weeks, median BW 845 g) were included. Mean sodium intake was above the ESPGHAN recommendation, 4.58 mmol/kg/day during the first 2 days and 1.99 mmol/kg/day during the following period. Incidence of PDA, IVH, and ROP was directly associated with sodium intake (OR 1.6, 1.3, and 1.4, respectively), but not with fluid supplementation. No association to BPD was found. The most important source for inadvertent sodium intake were 0.9% saline given by arterial lines. Sodium supplementation did not correlate directly with serum sodium levels, but a linear regression model combining sodium intake and fluid supplementation was able to predict serum sodium changes 24-48 h in advance (correlation coefficient of 0.294, p < 0.05). Conclusions: Sodium application substantially exceeded ESPGHAN recommendations in ELBW infants. An excess in sodium was associated with an overall increased morbidity, justifying increased efforts to identify inadvertent sodium sources in these patients with the aim to decrease sodium excess.

ALys amyloidosis caused by compound heterozygosity in exon 2 (Thr70Asn) and exon 4 (Trp112Arg) of the lysozyme gene.

Hereditary amyloidoses are caused by germline mutations, which increase the propensity of a protein to form cross-beta aggregates and deposit as amyloid. Hereditary amyloidoses are particularly interesting as they help to understand how changes in the primary structure of an otherwise non-amyloidogenic protein contribute to amyloidogenesis. Here we report on a novel form of systemic ALys amyloidosis, caused by compound heterozygosity in exon 2 (p.T70N) and exon 4 (p.W112R) of the lysozyme gene (LYZ), with both mutations being present on the same allele. This type of hereditary ALys amyloidosis is characterized by extended amyloid deposits in the upper gastrointestinal tract, entire colon, and kidney, leading to gastrointestinal bleeding. Both mutations are probably effective in disease manifestation. The novel mutation at position 112 in the mature protein is located within the alpha-helical domain of the protein and therefore outside the cluster of residues that has so far been implicated in ALys amyloidosis. Taken together with the p.T70N mutation, this results in a lysozyme species where the correct folding of various protein domains is probably impaired and increases the propensity of amyloid fibril formation. Interestingly, this form of ALys amyloidosis is also characterized by the occurrence of proteolytic fragments of lysozyme in the amyloid deposits.

Glycolytic oscillations in a model of a lactic acid bacterium metabolism.

Glycolytic oscillations in yeast have been extensively studied. It is still unclear, if these oscillations are caused by the allosteric enzyme phosphofructokinase or the stoichiometry of glycolysis which contains an autocatalysis with respect to ATP. Bacterial glycolysis shows a different stoichiometry, however, also containing a stoichiometric autocatalysis. For Escherichia coli, the regulation of the enzyme phosphofructokinase is also assumed to be a major reason for oscillations to occur. We investigated glycolytic oscillations in a quantitative kinetic model for Streptococcus pyogenes set-up on the basis of experimental data. We found oscillations within physiologically feasible parameter ranges. We investigated the origin of these oscillations and conclude that, again, both the stoichiometry of the system, as well as its allosterically regulated enzymes can give rise to these oscillations. For the analysis we employed established and new optimization methods for finding oscillatory regimes and present these in the context of this study.