ORCID Profile
0000-0002-6109-1239
Current Organisation
Queensland Children's Hospital
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Publisher: Wiley
Date: 02-12-2005
DOI: 10.1111/J.1464-5491.2004.01359.X
Abstract: To determine the impact of insulin pump therapy (continuous subcutaneous insulin infusion) on key parameters of diabetes management including quality of life in children and adolescents with Type 1 diabetes mellitus (T1DM). All patients started on insulin pump therapy were prospectively followed before and after institution of insulin pump therapy. Data collected included age, duration of diabetes, glycated haemoglobin levels (HbA1c), anthropometric data and episodes of severe hypoglycaemia defined as hypoglycaemia resulting in coma or convulsion. A subset of patients also completed the Diabetes Quality of Life Instrument (DQOL) and Self-Efficacy for Diabetes Scale (SED) questionnaires to assess quality of life. At the time of analysis, 100 patients had been managed with insulin pump therapy. The mean age when starting pump therapy was 12.5 (3.9-19.6) years. Duration of therapy ranged from 0.2 to 4.0 years (mean 1.4 years, median 1.5 years). HbA1c decreased from 8.3 +/- 0.1% prior to pump therapy to 7.8 +/- 0.1% (P < 0.0001). Episodes of severe hypoglycaemia decreased from 32.9 to 11.4 per 100 patient years. Components of quality of life measures showed improvement on pump treatment. BMI standard deviation scores (z scores) did not increase. Pump therapy is proving an effective means of insulin therapy in the young patient that shows promise to improve glycaemic control with a reduction in hypoglycaemia frequency. Quality of Life measures suggest that psychosocial outcomes may be improved.
Publisher: The Endocrine Society
Date: 2010
DOI: 10.1210/JC.2009-1003
Abstract: Glucocorticoid resistance is a rare genetic condition characterized by reduced sensitivity to cortisol signaling and subsequent hyperactivation of the hypothalamic-pituitary-adrenal axis. The objective was to confirm the diagnosis of glucocorticoid resistance in the patient, to determine the degree of suppression of cortisol and ACTH levels in response to dexamethasone, and to determine the underlying genetic abnormality and functional consequences of the mutation. The patient presented on the first day of life with profound hypoglycemia. Initial cortisol levels were appropriately elevated however, the patient was found to have persistently elevated levels of both cortisol and ACTH. The baby developed a tanned appearance and severe hypertension and fatigued easily with feeding. Serial oral dexamethasone suppression tests were performed with doses escalating from 0.125 mg to 12 mg dexamethasone given at 2300 h. Sequencing of the glucocorticoid receptor gene was performed along with functional studies of the glucocorticoid receptor. GH secretion was assessed with an arginine glucagon stimulation test. Cortisol and ACTH levels did not suppress with doses of up to 12 mg dexamethasone. A 2-bp deletion was found at amino acid position 773 of the glucocorticoid receptor ligand binding domain. A complete lack of dexamethasone binding and in vitro biological effect was demonstrated. GH stimulation testing was consistent with GH deficiency. The homozygous mutation in the ligand-binding domain of the glucocorticoid receptor gene resulted in a functionally inactive glucocorticoid receptor and apparent complete glucocorticoid resistance with biochemical GH deficiency.
Publisher: The Endocrine Society
Date: 03-2007
DOI: 10.1210/JC.2006-2263
Abstract: Exercise increases the risk of hypoglycemia in type 1 diabetes. This study aimed to investigate how the amount of glucose required to prevent an exercise-mediated fall in glucose level changes over time in adolescents with type 1 diabetes. The study took place at a tertiary pediatric referral center. Nine adolescents with type 1 diabetes mellitus (five males, four females, aged 16 +/- 1.8 yr, diabetes duration 8.2 +/- 4.1 yr, hemoglobin A1c 7.8 +/- 0.8%, mean +/- SD) were subjected on two different occasions to a rest or 45 min of exercise at 95% of their lactate threshold. Insulin was administered iv at a rate based on their usual insulin dose, with similar plasma insulin levels for both studies (82.1 +/- 19.0, exercise vs. 82.7 +/- 16.4 pmol/liter, rest). Glucose was infused to maintain euglycemia for 18 h. Glucose infusion rates required to maintain euglcycemia and levels of counterregulatory hormones were compared between rest and exercise study nights. Glucose infusion rates to maintain stable glucose levels were elevated during and shortly after exercise, compared with the rest study, and again from 7-11 h after exercise. Counterregulatory hormone levels were similar between exercise and rest studies except for peaks in the immediate postexercise period (epinephrine, norepinephrine, GH, and cortisol peaks: 375.6 +/- 146.9 pmol/liter, 5.59 +/- 0.73 nmol/liter, 71.9 +/- 14.8 mIU/liter, and 558 +/- 69 nmol/liter, respectively). The biphasic increase in glucose requirements to maintain euglycemia after exercise suggests a unique pattern of early and delayed risk for nocturnal hypoglycemia after afternoon exercise.
Publisher: Hindawi Limited
Date: 23-08-2012
DOI: 10.1111/J.1399-5448.2012.00890.X
Abstract: Vitamin D is synthesised in the skin through the action of UVB radiation (sunlight), and 25-hydroxy vitamin D (25OHD) measured in serum as a marker of vitamin D status. Several studies, mostly conducted in high latitudes, have shown an association between type 1 diabetes mellitus (T1DM) and low serum 25OHD. We conducted a case-control study to determine whether, in a sub-tropical environment with abundant sunlight (latitude 27.5°S), children with T1DM have lower serum vitamin D than children without diabetes. Fifty-six children with T1DM (14 newly diagnosed) and 46 unrelated control children participated in the study. Serum 25OHD, 1,25-dihydroxy vitamin D (1,25(OH)(2) D) and selected biochemical indices were measured. Vitamin D receptor (VDR) polymorphisms Taq1, Fok1, and Apa1 were genotyped. Fitzpatrick skin classification, self-reported daily hours of outdoor exposure, and mean UV index over the 35 d prior to blood collection were recorded. Serum 25OHD was lower in children with T1DM (n = 56) than in controls (n = 46) [mean (95%CI) = 78.7 (71.8-85.6) nmol/L vs. 91.4 (83.5-98.7) nmol/L, p = 0.02]. T1DM children had lower self-reported outdoor exposure and mean UV exposure, but no significant difference in distribution of VDR polymorphisms. 25OHD remained lower in children with T1DM after covariate adjustment. Children newly diagnosed with T1DM had lower 1,25(OH)(2) D [median (IQR) = 89 (68-122) pmol/L] than controls [121 (108-159) pmol/L, p = 0.03], or children with established diabetes [137 (113-153) pmol/L, p = 0.01]. Children with T1DM have lower 25OHD than controls, even in an environment of abundant sunlight. Whether low vitamin D is a risk factor or consequence of T1DM is unknown.
Publisher: SAGE Publications
Date: 16-04-2010
Abstract: We present the case of an eight-year-old boy with advanced isosexual precocity associated with an elevated serum total-beta human chorionic gonadotrophin (HCG) and markedly elevated serum total testosterone. Radiological investigation discovered a lesion in the left thalamus and no peripheral tumour. Serum:cerebrospinal fluid (CSF) HCG ratio was approximately 1:1, consistent with a central nervous system source of HCG, with thalamic germinoma strongly suspected. Consent was not obtained for biopsy of the lesion. The patient underwent multiagent chemotherapy with return of serum HCG to normal. We discuss mechanisms of HCG-mediated sexual precocity in both boys and girls and the importance of CSF HCG.
No related grants have been discovered for Sarah McMahon.