Diabetic Ketoacidosis at Onset of Type 1 Diabetes and Long-term HbA1c in 7,961 Children and Young Adults in the Australasian Diabetes Data Network

OBJECTIVE

The relationship between diabetic ketoacidosis (DKA) at diagnosis of type 1 diabetes and long-term glycemic control varies between studies. We aimed, firstly, to characterize the association of DKA and its severity with long-term HbA1c in a large contemporary cohort, and secondly, to identify other independent determinants of long-term HbA1c.

RESEARCH DESIGN AND METHODS

Participants were 7,961 children and young adults diagnosed with type 1 diabetes by age 30 years from 2000 to 2019 and followed prospectively in the Australasian Diabetes Data Network (ADDN) until 31 December 2020. Linear mixed-effect models related variables to HbA1c.

RESULTS

DKA at diagnosis was present in 2,647 participants (33.2%). Over a median 5.6 (interquartile range 3.2, 9.4) years of follow-up, participants with severe, but not moderate or mild, DKA at diagnosis had a higher mean HbA1c (+0.23%, 95% CI 0.11,0.28; [+2.5 mmol/mol, 95% CI 1.4,3.6]; P < 0.001) compared with those without DKA. Use of continuous subcutaneous insulin infusion (CSII) was independently associated with a lower HbA1c (-0.28%, 95% CI -0.31, -0.25; [-3.1 mmol/mol, 95% CI -3.4, -2.8]; P < 0.001) than multiple daily injections, and CSII use interacted with severe DKA to lower predicted HbA1c. Indigenous status was associated with higher HbA1c (+1.37%, 95% CI 1.15, 1.59; [+15.0 mmol/mol, 95% CI 12.6, 17.4]; P < 0.001), as was residing in postcodes of lower socioeconomic status (most vs. least disadvantaged quintile +0.43%, 95% CI 0.34, 0.52; [+4.7 mmol/mol, 95% CI 3.4, 5.6]; P < 0.001).

CONCLUSIONS

Severe, but not mild or moderate, DKA at diagnosis was associated with a marginally higher HbA1c over time, an effect that was modified by use of CSII. Indigenous status and lower socioeconomic status were independently associated with higher long-term HbA1c.

Determinants of Cardiovascular Risk in 7000 Youth With Type 1 Diabetes in the Australasian Diabetes Data Network

CONTEXT

Cardiovascular disease occurs prematurely in type 1 diabetes. The additional risk of overweight is not well characterized.

OBJECTIVE

The primary aim was to measure the impact of body mass index (BMI) in youth with type 1 diabetes on cardiovascular risk factors. The secondary aim was to identify other determinants of cardiovascular risk.

DESIGN

Observational longitudinal study of 7061 youth with type 1 diabetes followed for median 7.3 (interquartile range [IQR] 4-11) years over 41 (IQR 29-56) visits until March 2019.

SETTING

15 tertiary care diabetes centers in the Australasian Diabetes Data Network.Participants were aged 2 to 25 years at baseline, with at least 2 measurements of BMI and blood pressure.

MAIN OUTCOME MEASURE

Standardized systolic and diastolic blood pressure scores and non-high-density lipoprotein (HDL) cholesterol were co-primary outcomes. Urinary albumin/creatinine ratio was the secondary outcome.

RESULTS

BMI z-score related independently to standardized blood pressure z- scores and non-HDL cholesterol. An increase in 1 BMI z-score related to an average increase in systolic/diastolic blood pressure of 3.8/1.4 mmHg and an increase in non-HDL cholesterol (coefficient + 0.16 mmol/L, 95% confidence interval [CI], 0.13-0.18; P < 0.001) and in low-density lipoprotein (LDL) cholesterol. Females had higher blood pressure z-scores, higher non-HDL and LDL cholesterol, and higher urinary albumin/creatinine than males. Indigenous youth had markedly higher urinary albumin/creatinine (coefficient + 2.15 mg/mmol, 95% CI, 1.27-3.03; P < 0.001) and higher non-HDL cholesterol than non-Indigenous youth. Continuous subcutaneous insulin infusion was associated independently with lower non-HDL cholesterol and lower urinary albumin/creatinine.

CONCLUSIONS

BMI had a modest independent effect on cardiovascular risk. Females and Indigenous Australians in particular had a more adverse risk profile.

Morbidity and mortality meetings at Australian major trauma centres: A proof of concept study

Background

Morbidity and mortality meetings are held at all Australian major trauma centres and provide a forum to identify problems and improve practices. Meetings should focus on addressing factors in the system to prevent similar errors occurring, rather than individual culpability. This paper describes current meeting practices and assesses the use of a systems approach.

Methods

This proof of concept study used a convenience sample of four Australian major trauma centres. Trauma leaders at each centre were surveyed regarding morbidity and mortality meeting practices. The use of a systems approach was measured by assessing practices against the London Protocol for Systems Analysis of Clinical Incidents. Meeting participants were also surveyed regarding perceptions of the objectives and effectiveness of meetings.

Results

This study found variable utilisation of a systems approach. Cases are not routinely analysed for contributing system factors and effective processes are not always used to correct problems that are identified. Meeting practices also vary between centres in terms of frequency, case selection criteria and use of audit filters. Participants generally view quality improvement as the most important objective of meetings.

Conclusion

Morbidity and mortality meeting practices vary between Australian major trauma centres and a systems approach has not been fully adopted.

Standardising trauma monitoring: the development of a minimum dataset for trauma registries in Australia and New Zealand

INTRODUCTION

Trauma registries are central to the implementation of effective trauma systems. However, differences between trauma registry datasets make comparisons between trauma systems difficult. In 2005, the collaborative Australian and New Zealand National Trauma Registry Consortium began a process to develop a bi-national minimum dataset (BMDS) for use in Australasian trauma registries. This study aims to describe the steps taken in the development and preliminary evaluation of the BMDS.

METHODS

A working party comprising sixteen representatives from across Australasia identified and discussed the collectability and utility of potential BMDS fields. This included evaluating existing national and international trauma registry datasets, as well as reviewing all quality indicators and audit filters in use in Australasian trauma centres. After the working party activities concluded, this process was continued by a number of interested individuals, with broader feedback sought from the Australasian trauma community on a number of occasions. Once the BMDS had reached a suitable stage of development, an email survey was conducted across Australasian trauma centres to assess whether BMDS fields met an ideal minimum standard of field collectability. The BMDS was also compared with three prominent international datasets to assess the extent of dataset overlap. Following this, the BMDS was encapsulated in a data dictionary, which was introduced in late 2010.

RESULTS

The finalised BMDS contained 67 data fields. Forty-seven of these fields met a previously published criterion of 80% collectability across respondent trauma institutions; the majority of the remaining fields either could be collected without any change in resources, or could be calculated from other data fields in the BMDS. However, comparability with international registry datasets was poor. Only nine BMDS fields had corresponding, directly comparable fields in all the national and international-level registry datasets evaluated.

CONCLUSION

A draft BMDS has been developed for use in trauma registries across Australia and New Zealand. The email survey provided strong indications of the utility of the fields contained in the BMDS. The BMDS has been adopted as the dataset to be used by an ongoing Australian Trauma Quality Improvement Program.

Trust and confidence: towards mutual acceptance of ethics committee approval of multicentre studies

AIMS

To compare issues raised by Human Research Ethics Committees (HREC) during the ethics review process and to determine the length of time taken to gain HREC approval for multicentre research studies.

METHODS

Review and analysis of HREC documentation and correspondence for all multicentre research studies were conducted through three HREC under the auspices of Cancer Trials Australia, Melbourne, Victoria, Australia, between November 1997 and March 2001 to determine the variance of documentation, correspondence and recommendations across the three HREC and the time taken for study approval.

RESULTS

Thirty-one projects were submitted to any two of the HREC (16 studies) or all three HREC (15 studies). The median time for study approval at an individual HREC was 75 days, but it was 111 days for approval at all participating sites. There were 554 clarifications or comments made by the reviewing HREC, the majority of which had no significant bearing on the ethical or scientific calibre of the study. There was only one study in which a significant protocol change was requested by a HREC.

CONCLUSIONS

Multicentre study approvals are delayed when submitted to multiple HREC. The three HREC raised similar issues without substantive differences in their recommendations. A process for the mutual acceptance of HREC recommendations could facilitate multicentre research.

Cathepsin D cleaves aggrecan at unique sites within the interglobular domain and chondroitin sulfate attachment regions that are also cleaved when cartilage is maintained at acid pH

Bovine aggrecan was digested with bovine cathepsin D at pH 5.2 under conditions of partial digestion and the resulting aggrecan core protein fragments were separated by electrophoresis on gradient polyacrylamide gels. The fragments were characterized by their reactivity to specific antibodies and by N-terminal amino acid sequencing. It was also demonstrated that cathepsin D cleaved bovine aggrecan at five sites within the core protein, between residues Phe(342)-Phe(343) in the interglobular domain, Leu(1462)-Val(1463) between the chondroitin sulfate attachment regions 1 and 2 and Leu(1654)-Val(1655), Phe(1754)-Val(1755) and Leu(1854)-Ile(1855) that are located within the chondroitin sulfate attachment region 2 of the core protein. The time course of digestion showed that there was a continued degradation of aggrecan and there was no preferential cleavage of the core protein at any one site. It was shown that cathepsin D digested aggrecan over the pH range 5.2-6.5 resulting in the same products. When bovine cartilage was maintained in explant culture at pH 5.2 there was a rapid loss of both radiolabeled and chemical pools of sulfated glycosaminoglycans into the culture medium and this loss was inhibited by the inclusion in the medium of the aspartic proteinase inhibitor, pepstatin A. The aggrecan core protein fragments appearing in the medium of cultures maintained at pH 5.2 were characterized and it was shown that the fragments had N-terminal sequences starting at Phe(343), Ile(1855), and Val(1755) or Val(1463). This work demonstrates that cathepsin D present within the extracellular matrix of articular cartilage has the potential to contribute to the proteolytic processing of the core protein of aggrecan in this tissue.

Expression of anchorin CII (cartilage annexin V) in human young, normal adult, and osteoarthritic cartilage

In its tissue-specific function as a collagen receptor of chondrocytes, cartilage annexin V (anchorin CII) occupies a key position in the organization of the cell-extracellular matrix (ECM) junction for the tissue. The general role of annexin V (Anx V) in other tissues suggests involvement in cellular secretory processes and in regulation of apoptosis. Immunohistochemical analysis of Anx V in growth plate cartilage, confirmed by in situ hybridization, suggests that Anx V is prominently expressed and forms a major constituent of growth plate chondrocytes. Anx V epitopes are also located in the pericellular matrix of hypertrophic cartilage. In adult articular cartilage the expression is downregulated, with the highest levels of immunostaining found in the upper third of the articular cartilage layers and almost no antigen found in the deep layers. Osteoarthritic (OA) cartilage is characterized by a significant upregulation of message and protein throughout the entire depth of the tissue, an accumulation of cytoplasmic annexin V epitopes, and a release of epitopes into the pericellular and interterritorial matrix, in part co-localized with granular structures. Therefore, Anx V expression and tissue distribution may serve as a histological marker for metabolic alterations and for changes in the cellular phenotype associated with OA.

Catabolism of aggrecan by explant cultures of human articular cartilage in the presence of retinoic acid

The N-terminal amino acid sequence of human aggrecan was determined and it was shown that two sequences were present. The major sequence, AVTVE-, accounted for 60% of the aggrecan and started at alanine residue 17 of the human aggrecan core protein cDNA sequence (K. Doege et al. (1991) J. Biol. Chem. 266, 894-920). The other N-terminal sequence, VETX-, started at valine residue 20. Characterization of aggrecan core protein peptides present in the matrix of adult human articular cartilage showed that at least 11 aggrecan core proteins were present with approximate M(r) between 300,000 and 43,000. All these core proteins were found to have the same N-terminal sequences as that observed in human aggrecan. When articular cartilage was placed in explant culture in medium containing 10(-6) M retinoic acid there was a 3.5-fold increase in the loss of aggrecan into the culture medium compared to tissue maintained in medium alone or medium containing 20% (v/v) newborn calf serum. Analysis of the aggrecan core protein fragments that were released to the culture medium containing 10(-6) M retinoic acid showed the presence of 13 core protein peptides of M(r) between 300,000 and 43,000. The 11 smaller peptides of M(r) 230,000 to 43,000 were shown to have the N-terminal sequence ARGS-. This sequence which starts at residue 393 of the human aggrecan core protein is located within the interglobular region between the G1 and G2 domains and is the site of aggrecan catabolism by the putative protease aggrecanase. The presence of core proteins of varying sizes but with the same N-terminal sequence reflects proteolytic processing from the C-terminal end of the core protein that was also observed in the aggrecan macromolecules extracted from the matrix of human articular cartilage. This proteolytic processing was also evident but to a lesser extent in newly synthesized 35S-labeled aggrecan macromolecules.

Mechanism of catabolism of aggrecan by articular cartilage

Characterization of aggrecan core protein peptides appearing in the medium of adult articular cartilage maintained in tissue culture showed that eight major peptides could be detected. The two largest peptides had the same N-terminal sequence as bovine aggrecan core protein and probably represent partly degraded aggrecan lost to the medium in the form of the proteoglycan aggregate. The three next smallest peptides were all shown to have another N-terminal sequence which corresponded to a sequence in the interglobular domain starting at alanine residue 393 of the human aggrecan core protein (K. Doege et al., 1991, J. Biol. Chem. 266, 894-902). Two other peptides were isolated and shown to have two different N-terminal amino sequences corresponding to sequences in the chondroitin sulfate attachment domain 2 of the core protein starting at alanine residue 1839 and leucine residue 1939 of human aggrecan. This suggests that the catabolism of aggrecan by adult articular cartilage occurs by the proteolytic cleavage of the core protein of this proteoglycan at three separate sites. Examination of the amino acid sequences around each of these cleavage sites showed a similar pattern TEGE decreases ARGS, TAQE decreases AGEG, and VSQE decreases LGQR, suggesting that a single proteinase may be involved in the catabolism of aggrecan. Analysis of synovial fluids and serum of age-matched animals revealed the presence of aggrecan core protein peptides corresponding in size to those detected in vitro, thus indicating the cleavage observed in explant culture is the same as that which occurs in vivo.

Cleavage of proteoglycan aggregate by leucocyte elastase

The partial degradation of proteoglycan aggregate by human leucocyte elastase yielded products that banded with Mr 190,000, 140,000, 88,000, and 71,000 when analyzed by sodium dodecyl sulfate (SDS)-polyacrylamide electrophoresis. Analysis of these bands revealed that the 190,000- and 140,000-Da bands contained chondroitin and keratan sulfate stubs and had N-terminal amino acid sequences corresponding to a sequence starting at residue 398 of the core protein of rat or human aggrecan. With increased time of digestion, the staining intensities of the 190,000-, 140,000-, and 88,000-Da bands decreased relative to the 71,000-Da band. Analysis of the 88,000- and 71,000-Da bands showed that they contained peptides substituted only with keratan sulfate stubs and that each band contained two peptides with different N-terminal sequences. One of these corresponded to a sequence that started at residue 398 of rat or human aggrecan and the other to the N-terminal sequence of bovine aggrecan. Under conditions of complete digestion, bands of 71,000 and 56,000 Da which contained only keratan sulfate stubs were observed on SDS-polyacrylamide electrophoresis. The 71,000-Da band was shown to have a single sequence similar to that starting at residue 398 of human and rat aggrecan and thus represents the globular domain 2 (G2) of the core protein of aggrecan. The 56,000-Da band was shown to have a sequence similar to that of the N-terminal sequence of bovine aggrecan indicating that this peptide corresponds to the globular domain 1 (G1) of the molecule. These results suggest that leucocyte elastase cleaves the core protein of aggrecan between valine 397 and isoleucine 398, which are located in the interglobular domain linking the G1 and G2 domains of the core protein of aggrecan. Further digestion of the proteoglycan aggregate with elastase resulted in the cleavage of the core protein within the chondroitin sulfate attachment domains.