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1.
J Geriatr Psychiatry Neurol ; : 8919887241254470, 2024 May 20.
Article En | MEDLINE | ID: mdl-38769750

BACKGROUND: Neuropsychiatric symptoms affect the majority of dementia patients. Past studies report high rates of potentially inappropriate prescribing of psychotropic medications in this population. We investigate differences in neuropsychiatric diagnoses and psychotropic medication prescribing in a local US cohort by sex and race. METHODS: We utilize Medicare claims and prescription fill records in a cohort of 100% Medicare North and South Carolina beneficiaries ages 50 and above for the year 2017 with a dementia diagnosis. We identify dementia and quantify diagnosis of anxiety, depression and psychosis using validated coding algorithms. We search Medicare claims for antianxiety, antidepressant and antipsychotic medications to determine prescriptions filled. RESULTS: Anxiety and depression were diagnosed at higher rates in White patients; psychosis at higher rates in Black patients. (P < .001) Females were diagnosed with anxiety, depression and psychosis at higher rates than males (P < .001) and filled more antianxiety and antidepressant medications than males. (P < .001) Black and Other race patients filled more antipsychotic medications for anxiety, depression and psychosis than White patients. (P < .001) Antidepressants were prescribed at higher rates than antianxiety or antipsychotic medications across all patients and diagnoses. Of patients with no neuropsychiatric diagnosis, 11.4% were prescribed an antianxiety medication, 22.8% prescribed an antidepressant and 7.6% prescribed an antipsychotic. CONCLUSIONS: The high fill rate of antianxiety (benzodiazepine) medications in dementia patients, especially females is a concern. Patients are prescribed psychotropic medications at high rates. This practice may represent potentially inappropriate prescribing. Patient/caregiver education with innovative community outreach and care delivery models may help decrease medication use.

2.
Neurol Clin Pract ; 14(2): e200273, 2024 Apr.
Article En | MEDLINE | ID: mdl-38524836

Background and Objectives: There are racial disparities in health care services received by patients with neurodegenerative diseases, but little is known about disparities in the last year of life, specifically in high-value and low-value care utilization. This study evaluated racial disparities in the utilization of high-value and low-value care in the last year of life among Medicare beneficiaries with dementia or Parkinson disease. Methods: This was a retrospective, population-based cohort analysis using data from North and South Carolina fee-for-service Medicare claims between 2013 and 2017. We created a decedent cohort of beneficiaries aged 50 years or older at diagnosis with dementia or Parkinson disease. Specific low-value utilization outcomes were selected from the Choosing Wisely initiative, including cancer screening, peripheral artery stenting, and feeding tube placement in the last year of life. Low-value outcomes included hospitalization, emergency department visits, neuroimaging services, and number of days receiving skilled nursing. High-value outcomes included receipt of occupational and physical therapy, hospice care, and medications indicated for dementia and/or Parkinson disease. Results: Among 70,650 decedents, 13,753 were Black, 55,765 were White, 93.1% had dementia, and 7.7% had Parkinson disease. Adjusting for age, sex, Medicaid dual enrollment status, rural vs urban location, state (NC and SC), and comorbidities, Black decedents were more likely to receive low-value care including colorectal cancer screening (adjusted hazard ratio [aHR] 1.46 [1.32-1.61]), peripheral artery stenting (aHR 1.72 [1.43-2.08]), and feeding tube placement (aHR 2.96 [2.70-3.24]) and less likely to receive physical therapy (aHR 0.73 [0.64-0.85)], dementia medications (aHR 0.90 [0.86-0.95]), or Parkinson disease medications (aHR 0.88 [0.75-1.02]) within the last year of life. Black decedents were more likely to be hospitalized (aHR 1.28 [1.25-1.32]), more likely to be admitted to skilled nursing (aHR 1.09 [1.05-1.13]), and less likely to be admitted to hospice (aHR 0.82 [0.79-0.85]) than White decedents. Discussion: We found racial disparities in care utilization among patients with neurodegenerative disease in the last year of life, such that Black decedents were more likely to receive specific low-value care services and less likely to receive high-value supportive care than White decedents, even after adjusting for health status and socioeconomic factors.

3.
Biochimie ; 222: 109-122, 2024 Mar 01.
Article En | MEDLINE | ID: mdl-38431189

Three glucose-6-phosphatase catalytic subunits, that hydrolyze glucose-6-phosphate (G6P) to glucose and inorganic phosphate, have been identified, designated G6PC1-3, but only G6PC1 and G6PC2 have been implicated in the regulation of fasting blood glucose (FBG). Elevated FBG has been associated with multiple adverse clinical outcomes, including increased risk for type 2 diabetes and various cancers. Therefore, G6PC1 and G6PC2 inhibitors that lower FBG may be of prophylactic value for the prevention of multiple conditions. The studies described here characterize a G6PC2 inhibitor, designated VU0945627, previously identified as Compound 3. We show that VU0945627 preferentially inhibits human G6PC2 versus human G6PC1 but activates human G6PC3. VU0945627 is a mixed G6PC2 inhibitor, increasing the Km but reducing the Vmax for G6P hydrolysis. PyRx virtual docking to an AlphaFold2-derived G6PC2 structural model suggests VU0945627 binds two sites in human G6PC2. Mutation of residues in these sites reduces the inhibitory effect of VU0945627. VU0945627 does not inhibit mouse G6PC2 despite its 84% sequence identity with human G6PC2. Mutagenesis studies suggest this lack of inhibition of mouse G6PC2 is due, in part, to a change in residue 318 from histidine in human G6PC2 to proline in mouse G6PC2. Surprisingly, VU0945627 still inhibited glucose cycling in the mouse islet-derived ßTC-3 cell line. Studies using intact mouse liver microsomes and PyRx docking suggest that this observation can be explained by an ability of VU0945627 to also inhibit the G6P transporter SLC37A4. These data will inform future computational modeling studies designed to identify G6PC isoform-specific inhibitors.

4.
PNAS Nexus ; 3(2): pgae036, 2024 Feb.
Article En | MEDLINE | ID: mdl-38328777

Mediating the terminal reaction of gluconeogenesis and glycogenolysis, the integral membrane protein glucose-6-phosphate catalytic subunit 1 (G6PC1) regulates hepatic glucose production by catalyzing hydrolysis of glucose-6-phosphate (G6P) within the lumen of the endoplasmic reticulum. Consistent with its vital contribution to glucose homeostasis, inactivating mutations in G6PC1 causes glycogen storage disease (GSD) type 1a characterized by hepatomegaly and severe hypoglycemia. Despite its physiological importance, the structural basis of G6P binding to G6PC1 and the molecular disruptions induced by missense mutations within the active site that give rise to GSD type 1a are unknown. In this study, we determine the atomic interactions governing G6P binding as well as explore the perturbations imposed by disease-linked missense variants by subjecting an AlphaFold2 G6PC1 structural model to molecular dynamics simulations and in silico predictions of thermodynamic stability validated with robust in vitro and in situ biochemical assays. We identify a collection of side chains, including conserved residues from the signature phosphatidic acid phosphatase motif, that contribute to a hydrogen bonding and van der Waals network stabilizing G6P in the active site. The introduction of GSD type 1a mutations modified the thermodynamic landscape, altered side chain packing and substrate-binding interactions, and induced trapping of catalytic intermediates. Our results, which corroborate the high quality of the AF2 model as a guide for experimental design and to interpret outcomes, not only confirm the active-site structural organization but also identify previously unobserved mechanistic contributions of catalytic and noncatalytic side chains.

5.
Biosci Rep ; 44(1)2024 Jan 31.
Article En | MEDLINE | ID: mdl-38095063

G6PC2 encodes a glucose-6-phosphatase (G6Pase) catalytic subunit, primarily expressed in pancreatic islet ß cells, which modulates the sensitivity of insulin secretion to glucose and thereby regulates fasting blood glucose (FBG). Mutational analyses were conducted to validate an AlphaFold2 (AF2)-predicted structure of human G6PC2 in conjunction with a novel method to solubilize and purify human G6PC2 from a heterologous expression system. These analyses show that residues forming a predicted intramolecular disulfide bond are essential for G6PC2 expression and that residues forming part of a type 2 phosphatidic acid phosphatase (PAP2) motif are critical for enzyme activity. Additional mutagenesis shows that residues forming a predicted substrate cavity modulate enzyme activity and substrate specificity and residues forming a putative cholesterol recognition amino acid consensus (CRAC) motif influence protein expression or enzyme activity. This CRAC motif begins at residue 219, the site of a common G6PC2 non-synonymous single-nucleotide polymorphism (SNP), rs492594 (Val219Leu), though the functional impact of this SNP is disputed. In microsomal membrane preparations, the L219 variant has greater activity than the V219 variant, but this difference disappears when G6PC2 is purified in detergent micelles. We hypothesize that this was due to a differential association of the two variants with cholesterol. This concept was supported by the observation that the addition of cholesteryl hemi-succinate to the purified enzymes decreased the Vmax of the V219 and L219 variants ∼8-fold and ∼3 fold, respectively. We anticipate that these observations should support the rational development of G6PC2 inhibitors designed to lower FBG.


Blood Glucose , Glucose , Humans , Blood Glucose/metabolism , Glucose-6-Phosphatase/metabolism , Cholesterol , Sequence Analysis
6.
BMC Health Serv Res ; 23(1): 1377, 2023 Dec 08.
Article En | MEDLINE | ID: mdl-38066492

BACKGROUND: Type 2 diabetes mellitus (T2DM) is highly prevalent within the Indigenous Australian community. Novel glucose monitoring technology offers an accurate approach to glycaemic management, providing real-time information on glucose levels and trends. The acceptability and feasibilility of this technology in Indigenous Australians with T2DM has not been investigated. OBJECTIVE: This feasibility phenomenological study aims to understand the experiences of Indigenous Australians with T2DM using flash glucose monitoring (FGM). METHODS: Indigenous Australians with T2DM receiving injectable therapy (n = 8) who used FGM (Abbott Freestyle Libre) for 6-months, as part of a clinical trial, participated in semi-structured interviews. Thematic analysis of the interviews was performed using NVivo12 Plus qualitative data analysis software (QSR International). RESULTS: Six major themes emerged: 1) FGM was highly acceptable to the individual; 2) FGM's convenience was its biggest benefit; 3) data from FGM was a tool to modify lifestyle choices; 4) FGM needed to be complemented with health professional support; 5) FGM can be a tool to engage communities in diabetes management; and 6) cost of the device is a barrier to future use. CONCLUSIONS: Indigenous Australians with T2DM had positive experiences with FGM. This study highlights future steps to ensure likelihood of FGM is acceptable and effective within the wider Indigenous Australian community.


Blood Glucose Self-Monitoring , Diabetes Mellitus, Type 2 , Humans , Australia , Blood Glucose/analysis , Blood Glucose Self-Monitoring/methods , Diabetes Mellitus, Type 2/therapy , Feasibility Studies , Pilot Projects , Australian Aboriginal and Torres Strait Islander Peoples
7.
Inorg Chem ; 62(44): 18280-18289, 2023 Nov 06.
Article En | MEDLINE | ID: mdl-37870915

In this work, a series of novel boronium-bis(trifluoromethylsulfonyl)imide [TFSI-] ionic liquids (IL) are introduced and investigated. The boronium cations were designed with specific structural motifs that delivered improved electrochemical and physical properties, as evaluated through cyclic voltammetry, broadband dielectric spectroscopy, densitometry, thermogravimetric analysis, and differential scanning calorimetry. Boronium cations, which were appended with N-alkylpyrrolidinium substituents, exhibited superior physicochemical properties, including high conductivity, low viscosity, and electrochemical windows surpassing 6 V. Remarkably, the boronium ionic liquid functionalized with both an ethyl-substituted pyrrolidinium and trimethylamine, [(1-e-pyrr)N111BH2][TFSI], exhibited a 6.3 V window, surpassing previously published boronium-, pyrrolidinium-, and imidazolium-based IL electrolytes. Favorable physical properties and straightforward tunability make boronium ionic liquids promising candidates to replace conventional organic electrolytes for electrochemical applications requiring high voltages.

8.
Atherosclerosis ; 387: 117305, 2023 12.
Article En | MEDLINE | ID: mdl-37863699

BACKGROUND AND AIMS: Homozygous familial hypercholesterolaemia (FH) causes severe cardiovascular disease from childhood. Conventional drug therapy is usually ineffective; lipoprotein apheresis (LA) is often required. Liver transplantation (LT) can correct the metabolic defect but is considered a treatment of last resort. Newer drugs including lomitapide and evinacumab might reduce the need for apheresis and LT. We sought to determine the long-term outcomes following LT in Australia and New Zealand. METHODS: We analysed demographic, biochemical and clinical data from all patients in Australia and New Zealand who have received LT for homozygous FH, identified from the Australia and New Zealand Liver and Intestinal Transplant Registry. RESULTS: Nine patients (five female; one deceased; seven aged between 3 and 6 years at the time of LT and two aged 22 and 26 years) were identified. Mean follow-up was 14.1 years (range 4-27). Baseline LDL-cholesterol off all treatment was 23 ± 4.1 mmol/L. Mean LDL-cholesterol on medical therapy (including maximal statin therapy in all patients, ezetimibe in three and LA in five) was 11 ± 5.7 mmol/L (p < 0.001). After LT, mean LDL-cholesterol was 2.6 ± 0.9 mmol/L (p = 0.004) with three patients remaining on statin therapy and none on LA. One patient died from acute myocardial infarction (AMI) three years after LT. Two patients required aortic valve replacement, more than 10 years after LT. The remaining six patients were asymptomatic after eight to 21 years of follow-up. No significant adverse events associated with immunosuppression were reported. CONCLUSIONS: LT for homozygous FH was highly effective in achieving substantial long-term reduction in LDL-cholesterol concentrations in all nine patients. LT remains an option for severe cases of homozygous FH where drug therapy combined with apheresis is ineffective or unfeasible.


Anticholesteremic Agents , Blood Component Removal , Homozygous Familial Hypercholesterolemia , Hydroxymethylglutaryl-CoA Reductase Inhibitors , Hyperlipoproteinemia Type II , Liver Transplantation , Myocardial Infarction , Humans , Female , Child , Child, Preschool , Hyperlipoproteinemia Type II/diagnosis , Hyperlipoproteinemia Type II/genetics , Hyperlipoproteinemia Type II/therapy , Liver Transplantation/adverse effects , Hydroxymethylglutaryl-CoA Reductase Inhibitors/therapeutic use , Anticholesteremic Agents/adverse effects , New Zealand , Homozygote , Cholesterol, LDL , Blood Component Removal/adverse effects , Myocardial Infarction/complications
9.
J Mol Endocrinol ; 71(4)2023 11 01.
Article En | MEDLINE | ID: mdl-37855366

In the endoplasmic reticulum (ER) lumen, glucose-6-phosphatase catalytic subunit 1 and 2 (G6PC1; G6PC2) hydrolyze glucose-6-phosphate (G6P) to glucose and inorganic phosphate whereas hexose-6-phosphate dehydrogenase (H6PD) hydrolyzes G6P to 6-phosphogluconate (6PG) in a reaction that generates NADPH. 11ß-hydroxysteroid dehydrogenase type 1 (HSD11B1) utilizes this NADPH to convert inactive cortisone to cortisol. HSD11B1 inhibitors improve insulin sensitivity whereas G6PC inhibitors are predicted to lower fasting blood glucose (FBG). This study investigated whether G6PC1 and G6PC2 influence G6P flux through H6PD and vice versa. Using a novel transcriptional assay that utilizes separate fusion genes to quantitate glucocorticoid and glucose signaling, we show that overexpression of H6PD and HSD11B1 in the islet-derived 832/13 cell line activated glucocorticoid-stimulated fusion gene expression. Overexpression of HSD11B1 blunted glucose-stimulated fusion gene expression independently of altered G6P flux. While overexpression of G6PC1 and G6PC2 blunted glucose-stimulated fusion gene expression, it had minimal effect on glucocorticoid-stimulated fusion gene expression. In the liver-derived HepG2 cell line, overexpression of H6PD and HSD11B1 activated glucocorticoid-stimulated fusion gene expression but overexpression of G6PC1 and G6PC2 had no effect. In rodents, HSD11B1 converts 11-dehydrocorticosterone (11-DHC) to corticosterone. Studies in wild-type and G6pc2 knockout mice treated with 11-DHC for 5 weeks reveal metabolic changes unaffected by the absence of G6PC2. These data suggest that HSD11B1 activity is not significantly affected by the presence or absence of G6PC1 or G6PC2. As such, G6PC1 and G6PC2 inhibitors are predicted to have beneficial effects by reducing FBG without causing a deleterious increase in glucocorticoid signaling.


Glucocorticoids , Glucose-6-Phosphate , Animals , Mice , 11-beta-Hydroxysteroid Dehydrogenase Type 1/genetics , 11-beta-Hydroxysteroid Dehydrogenase Type 1/metabolism , Cell Line , Glucocorticoids/pharmacology , Glucocorticoids/metabolism , Glucose/metabolism , Glucose-6-Phosphate/metabolism , NADP/metabolism , Humans
10.
BMC Neurol ; 23(1): 325, 2023 Sep 12.
Article En | MEDLINE | ID: mdl-37700254

BACKGROUND: Medicare claims and electronic health record data are both commonly used for research and clinical practice improvement; however, it is not known how concordant diagnoses of neurodegenerative diseases (NDD, comprising dementia and Parkinson's disease) are in these data types. Therefore, our objective was to determine the sensitivity and specificity of neurodegenerative disease (NDD) diagnoses contained in structured electronic health record (EHR) data compared to Medicare claims data. METHODS: This was a retrospective cohort study of 101,980 unique patients seen at a large North Carolina health system between 2013-2017, which were linked to 100% North and South Carolina Medicare claims data, to evaluate the accuracy of diagnoses of neurodegenerative diseases in EHRs compared to Medicare claims data. Patients age > 50 who were enrolled in fee-for-service Medicare were included in the study. Patients were classified as having or not having NDD based on the presence of validated ICD-CM-9 or ICD-CM-10 codes associated with NDD or claims for prescription drugs used to treat NDD. EHR diagnoses were compared to Medicare claims diagnoses. RESULTS: The specificity of any EHR diagnosis of NDD was 99.0%; sensitivity was 61.3%. Positive predictive value and negative predictive value were 90.8% and 94.1% respectively. Specificity of an EHR diagnosis of dementia was 99.0%, and sensitivity was 56.1%. Specificity of an EHR diagnosis of PD was 99.7%, while sensitivity was 76.1%. CONCLUSIONS: More research is needed to investigate under-documentation of NDD in electronic health records relative to Medicare claims data, which has major implications for clinical practice (particularly patient safety) and research using real-world data.


Dementia , Neurodegenerative Diseases , Parkinson Disease , United States/epidemiology , Humans , Aged , Parkinson Disease/diagnosis , Parkinson Disease/epidemiology , Electronic Health Records , Medicare , Retrospective Studies , Dementia/diagnosis , Dementia/epidemiology
11.
Diabetes ; 72(11): 1534-1546, 2023 Nov 01.
Article En | MEDLINE | ID: mdl-37552863

It is well established that chronic glucocorticoid exposure causes hyperglycemia. While glucocorticoid receptor (GR) stimulates hepatic gluconeogenic gene transcription, additional mechanisms are activated by chronic glucocorticoid exposure to enhance gluconeogenesis. We found that chronic glucocorticoid treatment activated sphingosine-1-phosphate (S1P)-mediated signaling. Hepatic knockdown of hepatic S1P receptor 1 (S1PR1) had no effect on chronic glucocorticoid-induced glucose intolerance but elevated fasting plasma insulin levels. In contrast, hepatic S1PR3 knockdown exacerbated chronic glucocorticoid-induced glucose intolerance without affecting fasting plasma insulin levels. Finally, hepatic S1PR2 knockdown attenuated chronic glucocorticoid-induced glucose intolerance and reduced fasting plasma insulin levels. Here, we focused on dissecting the role of S1PR2 signaling in chronic glucocorticoid response on glucose homeostasis. We found that chronic glucocorticoid-induced hepatic gluconeogenesis, gluconeogenic gene expression, and GR recruitment to the glucocorticoid response elements (GREs) of gluconeogenic genes were all reduced in hepatic S1PR2 knockdown male mice. Hepatic S1PR2 knockdown also enhanced glucocorticoid suppression of RAR-related orphan receptor γ (RORγ) expression. Hepatic RORγ overexpression in hepatic S1PR2 knockdown mice restored glucocorticoid-induced glucose intolerance, gluconeogenic gene expression, and GR recruitment to their GREs. Conversely, RORγ antagonist and the reduction of hepatic RORγ expression attenuated such glucocorticoid effects. Thus, chronic glucocorticoid exposure induces an S1PR2-RORγ axis to cooperate with GR to enhance hepatic gluconeogenesis. Overall, this work provides novel mechanisms of and pharmaceutical targets against steroid-induced hyperglycemia.


Glucose Intolerance , Hyperglycemia , Insulins , Liver Diseases , Mice , Male , Animals , Glucocorticoids/metabolism , Gluconeogenesis/genetics , Glucose Intolerance/chemically induced , Glucose Intolerance/genetics , Glucose Intolerance/metabolism , Liver/metabolism , Hyperglycemia/metabolism , Receptors, Glucocorticoid/genetics , Receptors, Glucocorticoid/metabolism , Insulins/metabolism
12.
Diabetes ; 72(11): 1621-1628, 2023 Nov 01.
Article En | MEDLINE | ID: mdl-37552875

G6PC2 is predominantly expressed in pancreatic islet ß-cells where it encodes a glucose-6-phosphatase catalytic subunit that modulates the sensitivity of insulin secretion to glucose by opposing the action of glucokinase, thereby regulating fasting blood glucose (FBG). Prior studies have shown that the G6pc2 promoter alone is unable to confer sustained islet-specific gene expression in mice, suggesting the existence of distal enhancers that regulate G6pc2 expression. Using information from both mice and humans and knowledge that single nucleotide polymorphisms (SNPs) both within and near G6PC2 are associated with variations in FBG in humans, we identified several putative enhancers 3' of G6pc2. One region, herein referred to as enhancer I, resides in the 25th intron of Abcb11 and binds multiple islet-enriched transcription factors. CRISPR-mediated deletion of enhancer I in C57BL/6 mice had selective effects on the expression of genes near the G6pc2 locus. In isolated islets, G6pc2 and Spc25 expression were reduced ∼50%, and Gm13613 expression was abolished, whereas Cers6 and nostrin expression were unaffected. This partial reduction in G6pc2 expression enhanced islet insulin secretion at basal glucose concentrations but did not affect FBG or glucose tolerance in vivo, consistent with the absence of a phenotype in G6pc2 heterozygous C57BL/6 mice.


Blood Glucose , Islets of Langerhans , Animals , Humans , Mice , Blood Glucose/metabolism , Glucose/metabolism , Glucose-6-Phosphatase/genetics , Insulin/metabolism , Islets of Langerhans/metabolism , Mice, Inbred C57BL
13.
Biomolecules ; 13(7)2023 07 08.
Article En | MEDLINE | ID: mdl-37509130

(1) Background: Despite the existence of well-established, CSF-based biomarkers such as amyloid-ß and phosphorylated-tau, the pathways involved in the pathophysiology of Alzheimer's disease (AD) remain an active area of research. (2) Methods: We measured 3072 proteins in CSF samples of AD-biomarker positive mild cognitive impairment (MCI) participants (n = 38) and controls (n = 48), using the Explore panel of the Olink proximity extension assay (PEA). We performed group comparisons, association studies with diagnosis, age, and APOE ε4 status, overrepresentation analysis (ORA), and gene set enrichment analysis (GSEA) to determine differentially expressed proteins and dysregulated pathways. (3) Results: GSEA results demonstrated an enrichment of granulocyte-related and chemotactic pathways (core enrichment proteins: ITGB2, ITGAM, ICAM1, SELL, SELP, C5, IL1A). Moreover, some of the well-replicated, differentially expressed proteins in CSF included: ITGAM, ITGB2, C1QA, TREM2, GFAP, NEFL, MMP-10, and a novel tau-related marker, SCRN1. (4) Conclusion: Our results highlight the upregulation of neuroinflammatory pathways, especially chemotactic and granulocyte recruitment in CSF of early AD patients.


Alzheimer Disease , Cognitive Dysfunction , Humans , Pilot Projects , tau Proteins/cerebrospinal fluid , Proteomics , Alzheimer Disease/genetics , Cognitive Dysfunction/cerebrospinal fluid , Amyloid beta-Peptides/cerebrospinal fluid , Biomarkers/cerebrospinal fluid , Peptide Fragments , Nerve Tissue Proteins
15.
bioRxiv ; 2023 Aug 17.
Article En | MEDLINE | ID: mdl-36993754

Mediating the terminal reaction of gluconeogenesis and glycogenolysis, the integral membrane protein G6PC1 regulates hepatic glucose production by catalyzing hydrolysis of glucose-6-phosphate (G6P) within the lumen of the endoplasmic reticulum. Consistent with its vital contribution to glucose homeostasis, inactivating mutations in G6PC1 cause glycogen storage disease (GSD) type 1a characterized by hepatomegaly and severe hypoglycemia. Despite its physiological importance, the structural basis of G6P binding to G6PC1 and the molecular disruptions induced by missense mutations within the active site that give rise to GSD type 1a are unknown. Exploiting a computational model of G6PC1 derived from the groundbreaking structure prediction algorithm AlphaFold2 (AF2), we combine molecular dynamics (MD) simulations and computational predictions of thermodynamic stability with a robust in vitro screening platform to define the atomic interactions governing G6P binding as well as explore the energetic perturbations imposed by disease-linked variants. We identify a collection of side chains, including conserved residues from the signature phosphatidic acid phosphatase motif, that contribute to a hydrogen bonding and van der Waals network stabilizing G6P in the active site. Introduction of GSD type 1a mutations into the G6PC1 sequence elicits changes in G6P binding energy, thermostability and structural properties, suggesting multiple pathways of catalytic impairment. Our results, which corroborate the high quality of the AF2 model as a guide for experimental design and to interpret outcomes, not only confirm active site structural organization but also suggest novel mechanistic contributions of catalytic and non-catalytic side chains.

16.
Diabetes Metab Res Rev ; 39(5): e3631, 2023 Jul.
Article En | MEDLINE | ID: mdl-36893361

AIMS: Fracture risk is elevated in some type 2 diabetes patients. Bone fragility may be associated with more clinically severe type 2 diabetes, although prospective studies are lacking. It is unknown which diabetes-related characteristics are independently associated with fracture risk. In this post-hoc analysis of fracture data from the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) trial (ISRCTN#64783481), we hypothesised that diabetic microvascular complications are associated with bone fragility. MATERIALS AND METHODS: The FIELD trial randomly assigned 9795 type 2 diabetes participants (aged 50-75 years) to receive oral co-micronised fenofibrate 200 mg (n = 4895) or placebo (n = 4900) daily for a median of 5 years. We used Cox proportional hazards models to identify baseline sex-specific diabetes-related parameters independently associated with incident fractures. RESULTS: Over 49,470 person-years, 137/6138 men experienced 141 fractures and 143/3657 women experienced 145 fractures; incidence rates for the first fracture of 4∙4 (95% CI 3∙8-5∙2) and 7∙7 per 1000 person-years (95% CI 6∙5-9∙1), respectively. Fenofibrate had no effect on fracture outcomes. In men, baseline macrovascular disease (HR 1∙52, 95% CI 1∙05-2∙21, p = 0∙03), insulin use (HR 1∙62, HR 1∙03-2∙55, p = 0∙03), and HDL-cholesterol (HR 2∙20, 95% CI 1∙11-4∙36, p = 0∙02) were independently associated with fracture. In women, independent risk factors included baseline peripheral neuropathy (HR 2∙04, 95% CI 1∙16-3∙59, p = 0∙01) and insulin use (HR 1∙55, 95% CI 1∙02-2∙33, p = 0∙04). CONCLUSIONS: Insulin use and sex-specific complications (in men, macrovascular disease; in women, neuropathy) are independently associated with fragility fractures in adults with type 2 diabetes.


Diabetes Complications , Diabetes Mellitus, Type 2 , Fenofibrate , Fractures, Bone , Insulins , Adult , Female , Humans , Male , Diabetes Complications/drug therapy , Diabetes Mellitus, Type 2/complications , Diabetes Mellitus, Type 2/drug therapy , Fenofibrate/therapeutic use , Fractures, Bone/epidemiology , Fractures, Bone/etiology , Fractures, Bone/prevention & control , Insulins/therapeutic use , Prospective Studies , Risk Factors
17.
J Phys Chem B ; 127(6): 1429-1442, 2023 Feb 16.
Article En | MEDLINE | ID: mdl-36745872

The replacement of unsaturation with a cyclopropane motif as a (bio)isostere is a widespread strategy in bacteria to tune the fluidity of lipid bilayers and protect membranes when exposed to adverse environmental conditions, e.g., high temperature, low pH, etc. Inspired by this phenomenon, we herein address the relative effect of the cyclopropanation, both cis and trans configurations, on melting points, packing efficiency, and order of a series of lipid-like ionic liquids via a combination of thermophysical analysis, X-ray crystallography, and computational modeling. The data indicate there is considerable structural latitude possible when designing highly lipophilic ionic liquids that exhibit low melting points. While cyclopropanation of the lipid-like ionic liquids provides more resistance to aerobic degradation than their olefin analogs, the impact on the melting point decrease is not as pronounced. Our results demonstrate that incorporating one or more cyclopropyl moieties in long aliphatic chains of imidazolium-based ionic liquids is highly effective in lowering the melting points of such materials relative to their counterparts bearing linear, saturated, or thioether side chains. It is shown that the cyclopropane moiety effectively disrupts packing, favoring formation of gauche conformer in the side chains, resulting in enhancement of fluidity. This was irrespective of the configuration of the methylene bridge, although marked differences in the effect of cis- and trans-monocyclopropanated ILs on the melting points were observed.

18.
Heart Lung Circ ; 32(3): 287-296, 2023 Mar.
Article En | MEDLINE | ID: mdl-36707360

This position statement provides guidance to cardiologists and related specialists on the management of adult patients with elevated lipoprotein(a) [Lp(a)]. Elevated Lp(a) is an independent and causal risk factor for atherosclerotic cardiovascular disease (ASCVD) and calcific aortic valve disease (CAVD). While circulating Lp(a) levels are largely determined by ancestry, they are also influenced by ethnicity, hormones, renal function, and acute inflammatory events, such that measurement should be done after accounting for these factors. Further, circulating Lp(a) concentrations should be estimated using an apo(a)-isoform independent assay that employs appropriate calibrators and reports the results in molar units (nmol/L). Selective screening strategies of high-risk patients are recommended, but universal screening of the population is currently not advised. Testing for elevated Lp(a) is recommended in all patients with premature ASCVD and those considered to be at intermediate-to-high risk of ASCVD. Elevated Lp(a) should be employed to assess and stratify risk and to enable a decision on initiation or intensification of preventative treatments, such as cholesterol lowering therapy. In adult patients with elevated Lp(a) at intermediate-to-high risk of ASCVD, absolute risk should be reduced by addressing all modifiable behavioural, lifestyle, psychosocial and clinical risk factors, including maximising cholesterol-lowering with statin and ezetimibe and, where appropriate, PCSK9 inhibitors. Apheresis should be considered in patients with progressive ASCVD. New ribonucleic acid (RNA)-based therapies which directly lower Lp(a) are undergoing clinical trials.


Atherosclerosis , Cardiovascular Diseases , Adult , Humans , Atherosclerosis/diagnosis , Atherosclerosis/prevention & control , Australia/epidemiology , Cardiovascular Diseases/complications , Cholesterol , Lipoprotein(a) , Proprotein Convertase 9 , Risk Factors
19.
J Prosthet Dent ; 130(4): 597-601, 2023 Oct.
Article En | MEDLINE | ID: mdl-34996611

STATEMENT OF PROBLEM: Implant cantilever beam torque-limiting devices are affected by parallax, which may result in measurement read error. The overread or underread of the true target torque value could lead to premature failure of the screw joint of a dental implant. PURPOSE: The purpose of this in vitro study was to determine the effect of the operator's viewing angle relative to the cantilever beam and measurement reading scale when the torque-limiting device is actioned toward or away from the operator. MATERIAL AND METHODS: A beam torque wrench (Nobel Biocare USA) was used with the cantilever beam position fixed by using a wedge to read 32 Ncm on the marker arm. It was suspended in a vertical position relative to a digital single-lens reflex camera set at a fixed distance of 48 cm from the marker reading. The camera was rotated in 10-degree increments clockwise and counterclockwise relative to the cantilever beam reading, starting perpendicular to the marker. Photographs were recorded at each angle. Percentage measurement read error was calculated from dimensions of the cantilever beam torque device, including the beam diameter, distance from the marker arm, and the incremental marks on the measurement scale. Data were analyzed descriptively to determine the differences after comparison with the International Organization for Standardization (ISO) 6789-1:2017 recommendations. RESULTS: Photographs compared beam position relative to the 32-Ncm marker. The beam diameter was recorded as 1.5 mm, corresponding to approximately 5 Ncm. The distance between the marker arm and center of the beam was 0.08 mm. Percentage errors were greatest at lower torque values and increased relative to the viewing angle. Photographs showed that instrument overread was most likely to occur as the beam was moved away from the operator, which would result in potential undertightening unless compensated for. Underread was noted when the beam was pulled toward the operator. CONCLUSIONS: To prevent measurement read error when using an implant cantilever beam torque-limiting device, the operator should be positioned as close to a perpendicular viewing angle to the cantilever beam as possible. Viewing from an angle greater than 10 degrees from the perpendicular should be avoided for torque values less than 15 Ncm. For screws tightened between 25 Ncm and 35 Ncm, the viewing angle should be less than 30 degrees so that the applied torque is within the maximum deviation of the target torque value set by the ISO 6789-1:2017 recommendations.

20.
Intern Med J ; 53(5): 787-797, 2023 05.
Article En | MEDLINE | ID: mdl-35717668

BACKGROUND: Aboriginal and Torres Strait Islander people have higher rates of diabetes and its complications than non-Aboriginal people. Rumbalara Aboriginal Co-operative is the major primary healthcare provider for Aboriginal people in the Greater Shepparton region. AIMS: To evaluate the baseline metabolic parameters and presence of diabetes complications in people with type 2 diabetes attending Rumbalara Aboriginal Co-operative in 2017 and compare it with other Aboriginal and Torres Strait Islander studies and Australian specialist diabetes services. METHODS: Clinical and biochemical characteristics, including diabetes type, age, weight, body mass index (BMI), blood pressure, micro- and macrovascular complications, glycosylated haemoglobin (HbA1c), haemoglobin, renal function, lipid profile, urine albumin:creatinine ratio, diabetes medications, renin angiotensin system inhibition therapies, HMG-CoA reductase inhibitors and antiplatelet agents, were determined. RESULTS: One hundred and twenty-six individuals had diabetes, 121 had type 2 diabetes. One hundred and thirteen identified as Aboriginal and/or Torres Strait Islander. Median age was 57.5 (48-68) years, median HbA1c was 7.8% (6.8-9.6) and median BMI was 33.4 kg/m2 (29-42.3). Compared with other Australian Aboriginal and Torres Strait Islander populations, this population was older and had more obesity, but with better glycaemia management. Compared with specialist diabetes services, this population was of similar age, with greater BMI but comparable HbA1c. CONCLUSIONS: Aboriginal people living with type 2 diabetes attending this regional Aboriginal health service have comparable glycaemic management to specialist diabetes services in Australia, managed largely by primary care physicians with limited access to specialist care for the past 5 years.


Diabetes Mellitus, Type 2 , Health Services, Indigenous , Humans , Middle Aged , Australian Aboriginal and Torres Strait Islander Peoples , Diabetes Mellitus, Type 2/metabolism , Glycated Hemoglobin , Victoria
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