Dataset Information

Diurnal variability of glucose tetrasaccharide (Glc₄) excretion in patients with glycogen storage disease type III.

ABSTRACT:

Aim

The urinary glucose tetrasaccharide, Glc?1-6Glc?1-4Glc?1-4Glc (Glc₄), is a glycogen limit dextrin that is elevated in patients with glycogen storage disease (GSD) type III. We evaluated the potential of uncooked cornstarch therapy to interfere with Glc₄ monitoring, by measuring the diurnal variability of Glc₄ excretion in patients with GSD III.

Methods

Voids were collected at home over 24 hours, stored at 4°C and frozen within 48?hours. Glc₄ was analyzed using liquid chromatography-tandem mass spectrometry and normalized to creatinine.

Results

Subjects with GSD III (median age: 13.5?years, range: 3.7-62; n = 18) completed one or more 24-hour urine collection, and 28/36 collections were accepted for analysis. Glc₄ was elevated in 16/18 subjects (median: 13?mmol/mol creatinine, range: 2-75, reference range: <3). In collections with elevated Glc₄ (23/28), two-thirds (15/23) had low diurnal variability in Glc₄ excretion (coefficient of variation [CV%] <25). The diurnal variability was significantly correlated with the Glc₄ concentration (Pearson R =?.644, P 25%) was not consistently observed in repeat collections by the same subject.

Conclusions

The extent and variability of Glc₄ excretion relative to creatinine was not correlated with cornstarch dose. A majority of collections showed low variability over 24?hours. These findings support the use of single time-point collections to evaluate Glc₄ in patients with GSD III treated with cornstarch. However, repeat sampling over short time-periods will provide the most accurate assessment of Glc₄ excretion, as intraday variability may be increased in patients with high Glc₄ excretion.

SUBMITTER: Young SP

PROVIDER: S-EPMC7932871 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Interest in the production of carbon commodities from photosynthetically fixed CO2 has focused attention on cyanobacteria as a target for metabolic engineering and pathway investigation. We investigated the redirection of carbon flux in the model cyanobacterial species, Synechococcus elongatus PCC 7942, under nitrogen deprivation, for optimized production of the industrially desirable compound, pyruvate. Under nitrogen limited conditions, excess carbon is naturally stored as the multi-branched polysaccharide, glycogen, but a block in glycogen synthesis, via knockout mutation in the gene encoding ADP-glucose pyrophosphorylase (glgC), results in the accumulation of the organic acids, pyruvate and 2-oxoglutarate, as overflow excretions into the extracellular media. The ΔglgC strain, under 48 h of N-deprivation was shown to excrete pyruvate for the first time in this strain. Additionally, by increasing culture pH, to pH 10, it was possible to substantially elevate excretion of pyruvate, suggesting the involvement of an unknown substrate/proton symporter for export. The ΔglgC mutant was also engineered to express foreign transporters for glucose and sucrose, and then grown photomixotrophically with exogenous organic carbon supply, as added 5 mM glucose or sucrose during N- deprivation. Under these conditions we observed a fourfold increase in extracellular pyruvate excretion when glucose was added, and a smaller increase with added sucrose. Although the magnitude of pyruvate excretion did not correlate with the capacity of the ΔglgC strain for bicarbonate-dependent photosynthetic O2 evolution, or with light intensity, there was, however, a positive correlation observed between the density of the starter culture prior to N-deprivation and the final extracellular pyruvate concentration. The factors that contribute to enhancement of pyruvate excretion are discussed, as well as consideration of whether the source of carbon for pyruvate excretion might be derived from photosynthetic CO2 fixation or from remobilisation of existing carbon stores.

Dataset Information

Diurnal variability of glucose tetrasaccharide (Glc₄) excretion in patients with glycogen storage disease type III.

Aim

Methods

Results

Conclusions

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OmicsDI is part of the ELIXIR infrastructure

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Diurnal variability of glucose tetrasaccharide (Glc4) excretion in patients with glycogen storage disease type III.

Aim

Methods

Results

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OmicsDI is part of the ELIXIR infrastructure

Tweets

Diurnal variability of glucose tetrasaccharide (Glc₄) excretion in patients with glycogen storage disease type III.