Response: Early Assessment of the Risk for Gestational Diabetes Mellitus: Can Fasting Parameters of Glucose Metabolism Contribute to Risk Prediction? (Diabetes Metab J 2019;43:785–93)

No abstract available.

Early Assessment of the Risk for Gestational Diabetes Mellitus: Can Fasting Parameters of Glucose Metabolism Contribute to Risk Prediction?

BACKGROUND: An early identification of the risk groups might be beneficial in reducing morbidities in patients with gestational diabetes mellitus (GDM). Therefore, this study aimed to assess the biochemical predictors of glycemic conditions, in addition to fasting indices of glucose disposal, to predict the development of GDM in later stage and the need of glucose-lowering medication.METHODS: A total of 574 pregnant females (103 with GDM and 471 with normal glucose tolerance [NGT]) were included. A metabolic characterization was performed before 15+6 weeks of gestation by assessing fasting plasma glucose (FPG), fasting insulin (FI), fasting C-peptide (FCP), and glycosylated hemoglobin (HbA1c). Thereafter, the patients were followed-up until the delivery.RESULTS: Females with NGT had lower levels of FPG, FI, FCP, or HbA1c at the early stage of pregnancy, and therefore, showed an improved insulin action as compared to that in females who developed GDM. Higher fasting levels of FPG and FCP were associated with a higher risk of developing GDM. Moreover, the predictive accuracy of this metabolic profiling was also good to distinguish the patients who required glucose-lowering medications. Indices of glucose disposal based on C-peptide improved the predictive accuracy compared to that based on insulin. A modified quantitative insulin sensitivity check index (QUICKIc) showed the best differentiation in terms of predicting GDM (area under the receiver operating characteristics curve [ROC-AUC], 72.1%) or need for pharmacotherapy (ROC-AUC, 83.7%).CONCLUSION: Fasting measurements of glucose and C-peptide as well as the surrogate indices of glycemic condition could be used for stratifying pregnant females with higher risk of GDM at the beginning of pregnancy.

Interpretation of size-exclusion chromatography for the determination of molecular-size distribution of human immunoglobulins.

Molecular-size distribution by size-exclusion chromatography (SEC) [1] is used for the quantification of unwanted aggregated forms in therapeutic polyclonal antibodies, referred to as human immunoglobulins (Ig) in the European Pharmacopoeia. Considering not only the requirements of the monographs for human normal Ig (0338, 0918 and 2788) [2-4], but also the general chapter on chromatographic techniques (2.2.46) [5], several chromatographic column types are allowed for performing this test. Although the EDQM knowledge database gives only 2 examples of suitable columns as a guide for the user, these monographs permit the use of columns with different lengths and diameters, and do not prescribe either particle size or pore size, which are considered key characteristics of SEC columns. Therefore, the columns used may differ significantly from each other with regard to peak resolution, potentially resulting in ambiguous peak identity assignment. In some cases, this may even lead to situations where the manufacturer and the Official Medicines Control Laboratory (OMCL) in charge of Official Control Authority Batch Release (OCABR) have differing molecular-size distribution profiles for aggregates of the same batch of Ig, even though both laboratories follow the requirements of the relevant monograph. In the present study, several formally acceptable columns and the peak integration results obtained therewith were compared. A standard size-exclusion column with a length of 60 cm and a particle size of 10 µm typically detects only 3 Ig fractions, namely monomers, dimers and polymers. This column type was among the first reliable HPLC columns on the market for this test and very rapidly became the standard for many pharmaceutical manufacturers and OMCLs for batch release testing. Consequently, the distribution of monomers, dimers and polymers was established as the basis for the interpretation of the results of the molecular-size distribution test in the relevant monographs. However, modern columns with a smaller particle size provide better resolution and also reveal a class of components designated here as oligomers. This publication addresses the interpretation of the SEC test for Ig with respect to the following questions: - how can molecular-size distribution tests benefit from the use of the most recent column technology without changing the sense of well-established quality parameters? - is it possible to mathematically define a way to interpret chromatograms generated with various column types with the same fractionation range but different resolution power? - how should oligomers be considered regarding compliance with compendial specifications?

Establishment of the human albumin for electrophoresis Ph. Eur. BRP batches 3 and 4.

Due to the diminished stocks of the 2nd batch of the European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) for human albumin for electrophoresis, the European Directorate for the Quality of Medicines & HealthCare (EDQM) initiated in 2014 an international collaborative study for the establishment of two replacement batches. The study was run under the aegis of the Biological Standardisation Programme (BSP). Thirteen laboratories participated in the collaborative study to verify the suitability of the candidate reference preparations according to the Ph. Eur. monograph 0255 using the zone electrophoresis (ZE) method with either cellulose acetate and/or agarose as the testing medium. The candidate preparations were found suitable for the intended purpose and were subsequently adopted in June 2015 by the Ph. Eur. Commission as human albumin for electrophoresis BRP batches 3 and 4 with an assigned range for albumin of 93.8 per cent to 98.3 per cent of the total protein content.

Collaborative study for the establishment of the human immunoglobulin for electrophoresis Ph. Eur. BRP batch 3.

Due to the diminished stocks of the 2(nd) batch of the European Pharmacopoeia (Ph. Eur.) Biological Reference Preparation (BRP) for human immunoglobulin for electrophoresis, in 2013, the European Directorate for the Quality of Medicines and HealthCare (EDQM) initiated an international collaborative study for the establishment of a replacement batch. The study was run under the aegis of the Biological Standardisation Programme (BSP). Seventeen laboratories participated in the collaborative study to verify the suitability of the candidate reference preparation according to the Ph. Eur. monographs 0338 and 0918 using the zone electrophoresis (ZE) method with either cellulose acetate and/or agarose as the testing medium. The candidate preparation was found suitable for the intended purpose and was subsequently adopted by the Ph. Eur. Commission as the human immunoglobulin for electrophoresis BRP batch 3 with an assigned range for immunoglobulin of 79.8 % to 86.4 % of the total protein content.

Purification and characterization of the head-activator receptor from a multi-headed mutant of Chlorohydra viridissima.

In hydra the neuropeptide head activator (HA) is responsible for head-specific growth and differentiation processes. The effects of HA are mediated by high and low affinity receptors on hydra cells. In the current study HA receptors from a multi-headed mutant of Chlorohydra viridissima were solubilized from the membrane fraction using 1% Triton X-100 and 2.5 M urea. Scatchard analysis showed that the solubilized receptor had a Kd of 1.55 x 10(-9) M, indicating the low affinity subtype of the HA receptor. The solubilized receptor was purified by DMAE chromatography and subsequent affinity chromatography to homogeneity. SDS-PAGE revealed a single protein band with a molecular mass of 96 +/- 4 kDa. The native receptor eluted during gel filtration as a 113 kDa protein, and focussed with an isoelectric point of 4.8.

Cloning and expression of various staphylococcal genes encoding urease in Staphylococcus carnosus.

The urease genes from Staphylococcus xylosus C2a, Staphylococcus aureus U500, and S. aureus Newman were cloned in Staphylococcus carnosus using the plasmid vectors pCA43 and pCA44. The resulting respective recombinant plasmids pUra 402, pUraUH66, and pUra17 contained chromosomal DNA fragments with sizes of 5.6, 5.8, and 6.8 kb, respectively. Investigations on urease expression of the donor and recombinant strains in media with various nitrogen sources revealed that S. xylosus C2a produced urease constitutively at the highest specific activity. All of the recombinant strains had significantly lower urease activities than their DNA-donor strains. The nickel-dependence of urease was demonstrated in S. aureus U500 by a plate diffusion assay.

Characterisation of two types of head activator receptor on hydra cells.

A head activator (HA) analogue is described which even at high concentrations does not lose its biological activity. By cross-linking two HA molecules over a C8 spacer, the conformation was sufficiently altered, such that self-inactivation of HA by dimerisation was prevented. In addition, the introduction of a tyrosine instead of phenylalanine in one of the two HA molecules allowed radioactive labelling with iodine. This HA bipeptide was used to investigate the effect of HA at different concentrations and as ligand for HA receptor characterisation. We found that low concentrations (0.1-10 pM) sufficed to stimulate interstitial cell mitosis, and that higher concentrations (10-1000 pM) were required for the determination of interstitial cells to nerve cells. Binding of the radioactive HA ligand to living hydra and to purified membrane fractions was saturable and specific. Binding was compatible with HA analogues with a stable monomeric conformation, but less well with dimerising HA and HA analogues. Scatchard and kinetic analyses revealed the presence of at least two types of binding site in the membrane fraction, one with a 'lower' affinity (Kd = 10(-9) M) and one with a 100-fold higher affinity (Kd = 10(-11) M). Autoradiography showed that interstitial cells were differentially labelled, suggesting that the number or types of HA receptors may vary depending on cell cycle status. A mutant of hydra with a multiheaded morphology contained 6-20-times more HA receptors per mg protein than other hydra species or mutants.

Nickel-content of urease from Bacillus pasteurii.

Urease from Bacillus pasteurii DSM 33 was purified 34-fold to a maximum specific activity of 996.5 mumol urea min-1 mg-1 at 30 degrees C. Homogeneity was demonstrated by isoelectric focussing which showed a single protein zone corresponding to a pI of about 4.6. The native enzyme was demonstrated to have a molecular mass of 230,000 and to consist of identical subunits of 65,500, as measured by SDS electrophoresis. Radioactive 63Ni-nickel co-chromatographed with urease through gel filtration, ion-exchange, and affinity chromatography. Measuring specific radioactivity, the nickel content was found to be 1.00 (+/- 0.1) g-atom Ni per mol of subunit, and 0.82 g-atom Ni per mol as measured by atomic absorption spectrometry. This indicates that 1 atom of nickel is present in each of four subunits of the enzyme.