A will and a way to fund medicines for rare diseases: the story of human growth hormone replacement for adults with growth hormone deficiency.

Growth hormone (GH) replacement therapy was recently recommended by the Pharmaceutical Benefits Advisory Committee (PBAC) for listing on the Pharmaceutical Benefits Scheme for adults with severe GH deficiency and impaired quality of life. This approval was significant for two reasons. First, the application was initiated and coordinated by a health professional working group, who prepared a 'public interest' submission to PBAC. Second, it resulted in a recommendation to subsidise therapy for a rare disease after two prior rejections on the basis of uncertainty about efficacy and cost effectiveness. There are important lessons to learn about the power of professional groups to drive health policy and attain funding for rare diseases.

Impaired bone and muscle development in young people treated with antiepileptic drugs.

OBJECTIVE: Antiepileptic drugs (AEDs) are associated with reduced bone density, balance impairment, and increased fracture risk in adults. However, pediatric data are limited. Therefore, we aimed to examine bone, muscle, and balance outcomes in young patients taking AEDs. METHODS: We undertook a case-control study utilizing an AED exposure-discordant matched-pair approach. Subjects were aged 5-18 years with at least 12 months of AED exposure. Pairs were twins, nontwin siblings and first cousins, sex- and age-matched (to within 2 years), allowing for greater power than with unrelated control subjects. Dual energy x-ray absorptiometry (DXA), peripheral quantitative computed tomography (pQCT), and muscle force/balance were tested, with questionnaires were administered for bone health and epilepsy details. RESULTS: Twenty-three pairs were recruited, (median age 12.9 years [subjects] and 13.5 years [controls])-7 twin, 14 sibling, and 2 cousin pairs. Those taking AEDs had an increased prevalence of fractures (15 fractures in 8 subjects, compared with 4 fractures in 3 controls, p < 0.01). Trabecular volumetric bone mineral density (vBMD) measured by pQCT at the 4% site (tibia) was reduced by 14% (p = 0.03) in subjects. Subjects exerted a decreased maximum force compared to body weight (Fmax total/g) at the tibia. There were no differences seen in either bone mineral parameters measured by DXA or balance measures. SIGNIFICANCE: Young people taking AEDs reported more fractures and had reductions in tibial vBMD and lower limb muscle force compared to their matched controls. These findings suggest that further exploration of bone health issues of young patients on AED therapy is required. Longitudinal studies are required to confirm these changes in the muscle-bone unit and to further explore the clinical outcomes.

Low dose growth hormone treatment in infants and toddlers with Prader-Willi syndrome is comparable to higher dosage regimens.

OBJECTIVE: Evaluate benefit and risk of low dose growth hormone treatment (GHT, 4.5mg/m2/week) in very young children with Prader-Willi Syndrome (PWS). DESIGN: Prospective longitudinal clinical intervention. METHODS: We evaluated 31 infants (aged 2-12months) and 42 toddlers (13-24months) from the PWS-OZGROW database for height, weight and BMI using the World Health Organization standard deviation scores (SDSWHO) and PWS specific BMI (SDSPWS), bone age, insulin-like growth factor 1 (IGF-I) levels and adverse events over 3years of GHT. RESULTS: At commencement of GHT infants had a lower BMI SDSWHO (-0.88 vs 0.40) than toddlers, while toddlers had a lower height SDSWHO (-1.44 vs -2.09) (both P<0.05). All increased height SDSWHO (2year delta height infants +1.26 SDS, toddlers+1.21 SDS), but infants normalised height sooner, achieving a height SDS of -0.56 within 1year, while toddlers achieved a height SDS of -0.88 in two years. BMI SDSWHO increased, while BMI SDSPWS decreased (both P<0.0001) and remained negative. The GHT response did not differ with gestation (preterm 23%) or genetic subtype (deletion vs maternal uniparental disomy). Bone age advancement paralleled chronological age. All children had low serum IGF-I at baseline which increased, but remained within the age-based reference range during GHT (for 81% in first year). Four children had spinal curvature at baseline; two improved, two progressed to a brace and two developed an abnormal curve over the observation period. Mild to severe central and/or obstructive sleep apnoea were observed in 40% of children prior to GHT initiation; 11% commenced GHT on positive airway pressure (PAP), oxygen or both. Eight children ceased GHT due to onset or worsening of sleep apnoea: 2 infants in the first few months and 6 children after 6-24months. Seven resumed GHT usually after adjusting PAP but five had adenotonsillectomy. One child ceased GHT temporarily due to respiratory illness. No other adverse events were reported. Two children substantially improved their breathing shortly after GHT initiation. CONCLUSION: Initiation of GHT in infants with 4.5mg/m2/week was beneficial and comparable in terms of auxological response to a dose of 7mg/m2/week. Regular monitoring pre and post GH initiation assisted in early detection of adverse events. IGF-I levels increased with the lower dose but not excessively, which may lower potential long-term risks.

Disorders of sex development: insights from targeted gene sequencing of a large international patient cohort.

BACKGROUND: Disorders of sex development (DSD) are congenital conditions in which chromosomal, gonadal, or phenotypic sex is atypical. Clinical management of DSD is often difficult and currently only 13% of patients receive an accurate clinical genetic diagnosis. To address this we have developed a massively parallel sequencing targeted DSD gene panel which allows us to sequence all 64 known diagnostic DSD genes and candidate genes simultaneously. RESULTS: We analyzed DNA from the largest reported international cohort of patients with DSD (278 patients with 46,XY DSD and 48 with 46,XX DSD). Our targeted gene panel compares favorably with other sequencing platforms. We found a total of 28 diagnostic genes that are implicated in DSD, highlighting the genetic spectrum of this disorder. Sequencing revealed 93 previously unreported DSD gene variants. Overall, we identified a likely genetic diagnosis in 43% of patients with 46,XY DSD. In patients with 46,XY disorders of androgen synthesis and action the genetic diagnosis rate reached 60%. Surprisingly, little difference in diagnostic rate was observed between singletons and trios. In many cases our findings are informative as to the likely cause of the DSD, which will facilitate clinical management. CONCLUSIONS: Our massively parallel sequencing targeted DSD gene panel represents an economical means of improving the genetic diagnostic capability for patients affected by DSD. Implementation of this panel in a large cohort of patients has expanded our understanding of the underlying genetic etiology of DSD. The inclusion of research candidate genes also provides an invaluable resource for future identification of novel genes.

Intravenous glucagon in a deliberate insulin overdose in an adolescent with type 1 diabetes mellitus.

Massive insulin overdose may be associated with unpredictable and prolonged hypoglycemia. Concerns surrounding the potential provocation of insulin release from beta cells have previously prevented the use of intravenous glucagon as an adjunct to infusion of dextrose in this situation. We describe the case of a 15-yr-old boy with type 1 diabetes mellitus (T1DM) who presented with profound hypoglycemia following an overdose of an unknown quantity of premixed insulin. Owing to an increasing dextrose requirement and a dependence on hourly intramuscular glucagon injections, a continuous intravenous infusion of glucagon was commenced which successfully avoided the requirement for central venous access or concentrated dextrose infusion. Nausea was managed with anti-emetics. Intramuscular and subcutaneous glucagon is effective in the management of refractory and severe hypoglycemia in youth with both T1DM and hyperinsulinism. Concerns regarding the precipitation of rebound hypoglycemia with the use of intravenous glucagon do not relate to those with T1DM. This treatment option may be a useful adjunct in the management of insulin overdose in youth with T1DM and may avoid the requirement for invasive central venous access placement.

IGFBP-2 - taking the lead in growth, metabolism and cancer.

The activity of the Insulin-like Growth Factors (IGFs) ligands elicited via their receptors and transduced by various intracellular signal pathways is modulated by the IGF Binding Proteins (IGFBPs). Among all the IGFBPs, IGFBP-2 has been implicated in the regulation of IGF activity in most tissue and organs. Besides binding to IGFs in the circulation these IGF-regulatory activities of IGFBP-2 involve interactions with components of the extracellular matrix, cell surface proteoglycans and integrin receptors. In addition to these local peri-cellular activities, IGFBP-2 exerts other key functions within the nucleus, where IGFBP-2 directly or indirectly promotes transcriptional activation of specific genes. All of these IGFBP-2 activities, intrinsic or dependent on IGFs, contribute to its functional roles in growth/development, metabolism and malignancy as evidenced by studies in IGFBP-2 animal models and also by many in vitro studies. Finally, preclinical studies have demonstrated that IGFBP-2 administration can be beneficial in improving metabolic responses (inhibition of adipogenesis and enhanced insulin sensitivity), while blockade of IGFBP-2 appears to be an effective approach to inhibiting tumour growth and metastasis.

Turner syndrome patients with bicuspid aortic valves and renal malformations exhibit abnormal expression of X-linked inhibitor of apoptosis protein (XIAP).

OBJECTIVE: We analyzed mRNA expression of X-linked inhibitor of apoptosis protein (XIAP) in patients with Turner syndrome (TS) and examined its association with phenotypic features. SUBJECTS AND METHODS: XIAP mRNA expression levels were investigated in 98 patients with TS in total RNA extracted from blood leucocytes by real time quantitative polymerase chain reaction. RESULTS: Levels of XIAP mRNA were significantly lower in patients with bicuspid aortic valves (BAV; n=13) than those without (log XIAP -1.17±0.3 vs. -0.94±0.2, p=0.002). Significantly higher expression of XIAP mRNA was seen in patients with a mosaic karyotype and renal malformations (log XIAP -0.79±0.3 vs. -1.0±0.3, p=0.03). No correlations were seen between XIAP and other manifestations. CONCLUSION: Abnormal expression of XIAP may be an important underlying mechanism in the development of BAV and renal malformations in TS. However, abnormal XIAP mRNA expression, as determined from peripheral mononuclear cells, does not appear to explain all the somatic and visceral stigmata of TS.

Risk factors for decline in IQ in youth with type 1 diabetes over the 12 years from diagnosis/illness onset.

OBJECTIVE: This study examined illness-related change in intelligence quotient (IQ) in a cohort of youth with type 1 diabetes studied prospectively from disease onset in childhood to follow-up 12 years later in late adolescence/early adulthood. RESEARCH DESIGN AND METHODS: Participants included type 1 diabetes patients (n = 95; mean age at follow-up 21.3 years) and healthy control participants (HCs; n = 67; mean age at follow-up 21.0 years) from a cohort followed prospectively. Measures included Wechsler Preschool and Primary Scale of Intelligence-Revised, Wechsler Intelligence Scale for Children-Revised, and Wechsler Abbreviated Scale of Intelligence and prospective collection of data on metabolic control history. RESULTS: Young people with type 1 diabetes showed greater decline in verbal IQ (VIQ) and full-scale IQ (FSIQ), but not performance IQ (PIQ), than HCs. Within the diabetes group, a younger age at diabetes onset was associated with a decline in PIQ and FSIQ (P ≤ 0.001). A history of hypoglycemic seizures was associated with a decline in VIQ (P = 0.002). Long-term metabolic control was not associated with changes in IQ. Interaction terms were not significant, suggesting no moderating effect of one diabetes-related variable over another. CONCLUSIONS: The presence of diabetes may negatively influence some aspects of IQ over time. Specific illness risk factors, such as an earlier age of disease onset and a history of hypoglycemic seizures, appear to put the young person at greater risk. Academic progress of children identified as at risk should be monitored and educational supports provided if necessary.

Where should we measure waist circumference in clinically overweight and obese youth?

AIMS: Waist circumference (WC) measurement is a useful tool in the assessment of overweight/obese individuals, but standard measures may miss an apron of 'overhanging' fat (termed 'panniculus'). The objective of this study was to assess whether, in clinically overweight/obese youth, 'pannicular' WC better correlates with fat mass than a standard WC measurement. METHODS: Standard and pannicular WC, alongside body composition (BC) measures, were collected from 181 consultations on 127 overweight and obese children/adolescents (52% male; mean (standard deviation) age 12.5 (3.4) years). Correlation coefficients describe associations between WC and measures of BC, and between ΔWC and ΔBC, while linear regression models assessed which of the WC measures explained more of the variability in BC and ΔBC over time. RESULTS: Standard and pannicular WC were highly correlated (r = 0.95). Correlation coefficients with measures of BC were generally greater for pannicular than standard WC, with greatest correlations seen for whole body (r = 0.94 vs. 0.85, respectively) and truncal (r = 0.86 vs. 0.77) fat mass. Furthermore, pannicular and Δpannicular WC explained more variability in truncal fat and Δtruncal fat than the standard measure of WC. CONCLUSIONS: These data show that pannicular, rather than standard, WC measurements better correlate with absolute measures of fat mass, and their change over time, in clinically overweight/obese youth.

Comparison of Centers for Disease Control and Prevention and World Health Organization references/standards for height in contemporary Australian children: analyses of the Raine Study and Australian National Children's Nutrition and Physical Activity cohorts.

AIM: (i) To compare the Centers for Disease Control and Prevention (CDC) reference and World Health Organization (WHO) standard/reference for height, particularly with respect to short stature and eligibility for growth hormone (GH) treatment by applying them to contemporary Australian children; (ii) To examine the implications for identifying short stature and eligibility for GH treatment. METHODS: Children from the longitudinal Raine Study were serially measured for height from 1991 to 2005 (2-15-year-old girls (660) and boys (702) from Western Australia). In the cross-sectional Australian National Children's Nutrition and Physical Activity survey (2-16-year-old boys (2415) and girls (2379) from all states), height was measured in 2007. Heights were converted to standard deviation scores (SDSs) based on CDC and WHO. RESULTS: Means and standard deviations of height-SDS varied between CDC and WHO definitions and with age and gender within each definition. However, both identified similar frequencies of short stature (<1st centile for GH eligibility), although these were very significantly less than the anticipated 1% (0.1-0.7%) of the Australian cohorts. Mean heights in the Australian cohorts were greater than both the WHO and CDC means. CONCLUSIONS: Neither CDC nor WHO height standardisations accurately reflect the contemporary Australian child population. Australian children are taller than the CDC or WHO height means, and significantly less than 1% of Australian children are defined as being short using either CDC or WHO. This study suggests there may be a case for an Australian-specific standard/reference for height.

Leptin enhances insulin sensitivity by direct and sympathetic nervous system regulation of muscle IGFBP-2 expression: evidence from nonrodent models.

Leptin is produced from white adipose tissue and acts primarily to regulate energy balance. Obesity is associated with leptin resistance and increased circulating levels of leptin. Leptin has recently been shown to influence levels of IGF binding protein-2 (IGFBP-2), a protein that is reduced in obesity and type 2 diabetes. Overexpression of IGFBP-2 protects against obesity and type 2 diabetes. As such, IGFBP-2 signaling may represent a novel pathway by which leptin regulates insulin sensitivity. We sought to investigate how leptin regulates skeletal muscle IGFBP-2 levels and to assess the impact of this on insulin signaling and glucose uptake. In vitro experiments were undertaken in cultured human skeletal myotubes, whereas in vivo experiments assessed the effect of intracerebroventricular leptin on peripheral skeletal muscle IGFBP-2 expression and insulin sensitivity in sheep. Leptin directly increased IGFBP-2 mRNA and protein in human skeletal muscle through both signal transducer and activator of transcription-3 and phosphatidylinositol 3-kinase signaling, in parallel with enhanced insulin signaling. Silencing IGFBP-2 lowered leptin- and insulin-stimulated protein kinase B phosphorylation and glucose uptake. In in vivo experiments, intracerebroventricular leptin significantly increased hind-limb skeletal muscle IGFBP-2, an effect completely blocked by concurrent peripheral infusion of a ß-adrenergic blocking agent. Sheep receiving central leptin showed improvements in glucose tolerance and circulating insulin levels after an iv glucose load. In summary, leptin regulates skeletal muscle IGFBP-2 by both direct peripheral and central (via the sympathetic nervous system) mechanisms, and these likely impact on peripheral insulin sensitivity and glucose metabolism.

Comparison of weight- vs body surface area-based growth hormone dosing for children: implications for response.

OBJECTIVE: To compare weight (per kg)- vs body surface area (BSA, per m(2) )-based growth hormone (GH) dosing formats in children and to derive a useful conversion formula between the two formats. PATIENTS AND DESIGN: Growth hormone doses (>33,000) from 1874 children were obtained from the national Australian database (OZGROW) and used to derive conversion formulae and to confirm the accuracy of a conversion formula based on a weight-only BSA estimate. A further 27,000 doses were used to test the accuracy of all formulae. The best conversion formula was used to compare weight- and surface area-based GH dosing, which included an analysis of first year response (∆SDS height or growth velocity, GV). MEASUREMENTS: Growth hormone doses in mg/m(2) /wk and mg/kg/wk, dose estimates, residuals, first year ∆SDS, first year GV. RESULTS: The formula, [Formula: see text] based on a weight-only BSA estimate, provides accurate dose conversion (mean residual, 0·005 mg/kg/week). A constant mg/m(2) /week dose expressed in terms of mg/kg/week declines quickly with increasing body weight to approximately 15 kg after which the decline continues although less dramatically. For Australian patients, despite an increase in mean per m(2) dose with increased starting weight/age, the per kg dose decreased. This was associated with a greater decline in first year GV than estimated if a per kg dose had been maintained. CONCLUSIONS: Growth hormone doses can be accurately converted between formats. Surface area-based GH dosing is likely to result in a reduced height response as children become heavier when compared with weight-based GH dosing.

Response to growth hormone treatment in Prader-Willi syndrome: auxological criteria versus genetic diagnosis.

AIM: The Australian Prader-Willi Syndrome (PWS) database was established to monitor the efficacy and safety of growth hormone (GH) treatment in PWS. This study aims to compare response to GH based on eligibility criteria. METHODS: Comparative study: 72 children received GH on the basis of short stature or evidence of GH deficiency (pre-2009: PWS-SS) and 94 on a genetic diagnosis (post-2009: PWS-Dx). We report on mandatory patient data for GH prescription: median and standard deviation score (SDS) for height and body mass index (BMI), waist/height ratio, bone age/chronological age ratio and adverse events. Comparisons were made using non-parametric tests. RESULTS: At baseline, the PWS-SS cohort was shorter (height SDS: -2.6 vs. -1.1, P < 0.001), had a lower BMI (0.6 vs. 1.5 SDS, P < 0.05) and greater bone age delay (bone age/chronological age: 0.7 vs. 0.9, P < 0.05) than the PWS-Dx cohort. PWS-SS parents were shorter (mid-parental height SDS: -0.13 vs. 0.28, P < 0.005). Mean change in height over 2 years was 0.9 SDS and in BMI using PWS reference standards -0.3 SDSPWS (n = 106) (year 2, height SDS: PWS-SS = -1.7, PWS-Dx = 0.1; BMI SDSPWS : PWS-SS = -1.0, PWS-Dx = -0.6). The waist/height ratio reduced (PWS-Dx: 0.60 vs. 0.56, P < 0.05) and bone age delay was unchanged over this period. No serious adverse events were reported. CONCLUSIONS: The PWS-SS cohort represents a subgroup of the wider PWS-Dx population; however both cohorts improved height SDS with normalisation of height in the PWS-Dx cohort and lowering of BMI relative to PWS standards supporting the efficacy of treatment under the current Australian GH programme.

Overgrowth syndromes.

PURPOSE OF REVIEW: Human growth ensues from a complex interplay of physiological factors, in the wider setting of varying genetic traits and environmental influences. Intensive research in these divergent areas, and particularly in the field of genetics, continues to clarify the molecular basis of disorders which result in overgrowth, and it is therefore timely to provide a review of these findings. RECENT FINDINGS: This article provides an overview of the factors which regulate growth, followed by a discussion of the more commonly encountered overgrowth syndromes and their genetic basis as it is understood at the current time. There is also an added focus on recently discovered genetic associations in some conditions, such as Weaver, Perlman and Proteus syndromes. SUMMARY: New discoveries continue to be made regarding the genetic basis for many overgrowth syndromes and the development of a much needed molecular classification system for overgrowth may become possible as the interlinking functions of these genes on growth are unravelled. As there exists a wide spectrum of syndromes, disorders resulting in overgrowth can represent a diagnostic and therapeutic challenge, from those causing prenatal overgrowth with a poor prognosis to less severe genetic aberrations which are identified in later childhood or adult life.

Effects of fluctuating glucose levels on neuronal cells in vitro.

There is increasing evidence for glucose fluctuation playing a role in the damaging effects of diabetes on various organs, including the brain. We aimed to study the effects of glycaemic variation (GV) upon mitochondrial activity using an in vitro human neuronal model. The metabolic disturbance of GV in neuronal cells, was mimicked via exposure of neuroblastoma cells SH-SY5Y to constant glucose or fluctuating (i.e. 6 h cycles) for 24 and 48 h. Mitochondrial dehydrogenase activity was determined via MTT assay. Cell mitochondrial activity (MTT) was moderately decreased in constant high glucose, but markedly decreased following 24 and 48 h of cyclical glucose fluctuations. Glucose transport determined via 2-deoxy-D-[1-(14)C] glucose uptake was regulated in an exaggerated manner in response to glucose variance, accompanied by modest changes in GLUT 1 mRNA abundance. Osmotic components of these glucose effects were investigated in the presence of the osmotic-mimics mannitol and L: -glucose. Both treatments showed that fluctuating osmolality did not result in a significant change in mitochondrial activity and had no effects on (14)Cglucose uptake, suggesting that adverse effects on mitochondrial function were specifically related to metabolically active glucose fluctuations. Apoptosis gene expression showed that both intrinsic and extrinsic apoptotic pathways were modulated by glucose variance, with two major response clusters corresponding to (i) glucose stress-modulated genes, (ii) glucose mediated osmotic stress-modulated genes. Gene clustering analysis by STRING showed that most of the glucose stress-modulated genes were components of the intrinsic/mitochondrial apoptotic pathway including Bcl-2, Caspases and apoptosis executors. On the other hand the glucose mediated osmotic stress-modulated genes were mostly within the extrinsic apoptotic pathway, including TNF receptor and their ligands and adaptors/activators/initiators of apoptosis. Fluctuating glucose levels have a greater adverse effect on neuronal cell energy regulation mechanisms than either sustained high or low glucose levels.

Age-related loss of brain volume and T2 relaxation time in youth with type 1 diabetes.

OBJECTIVE: 2 Childhood-onset type 1 diabetes is associated with neurocognitive deficits, but there is limited evidence to date regarding associated neuroanatomical brain changes and their relationship to illness variables such as age at disease onset. This report examines age-related changes in volume and T2 relaxation time (a fundamental parameter of magnetic resonance imaging that reflects tissue health) across the whole brain. RESEARCH DESIGN AND METHODS: Type 1 diabetes, N = 79 (mean age 20.32 ± 4.24 years), and healthy control participants, N = 50 (mean age 20.53 ± 3.60 years). There were no substantial group differences on socioeconomic status, sex ratio, or intelligence quotient. RESULTS: Regression analyses revealed a negative correlation between age and brain changes, with decreasing gray matter volume and T2 relaxation time with age in multiple brain regions in the type 1 diabetes group. In comparison, the age-related decline in the control group was small. Examination of the interaction of group and age confirmed a group difference (type 1 diabetes vs. control) in the relationship between age and brain volume/T2 relaxation time. CONCLUSIONS: We demonstrated an interaction between age and group in predicting brain volumes and T2 relaxation time such that there was a decline in these outcomes in type 1 diabetic participants that was much less evident in control subjects. Findings suggest the neurodevelopmental pathways of youth with type 1 diabetes have diverged from those of their healthy peers by late adolescence and early adulthood but the explanation for this phenomenon remains to be clarified.

Growth hormone regimens in Australia: analysis of the first 3 years of treatment for idiopathic growth hormone deficiency and idiopathic short stature.

OBJECTIVE: To investigate response to growth hormone (GH) in the first, second and third years of treatment for all idiopathic GH-deficient (GHD) and idiopathic short stature (ISS) patients in Australia. CONTEXT: Eligibility for subsidized GH treatment in Australia is determined on auxological criteria for the indication of Short Stature and Slow Growth (SSSG), which includes ISS (SSSG-ISS). The biochemical GHD (BGHD, peak GH < 10 mU/l) and SSSG indications are treated similarly: starting dose of 4·5 mg/m(2)/week with provision for incremental dosing. Some ISS patients were specifically diagnosed with familial short stature (SSSG-FSS). DESIGN: Responses for each year of treatment for BGHD, SSSG-ISS and SSSG-FSS cohorts were compared in relation to influencing variables and with international benchmarks. The effect of incremental dosing was assessed. PATIENTS: Australian BGHD, SSSG-ISS and SSSG-FSS patients who had completed 1, 2, or 3 years of treatment and were currently receiving GH. MEASUREMENTS: Growth hormone dose, change in height-standard deviation score (ΔSDS) and growth velocity (GV). RESULTS: First-year response was 2-3 times greater than that in subsequent years: ΔSDS(1st year) = 0·92, 0·50 and 0·46 for BGHD, SSSG-ISS and SSSG-FSS, respectively. Responses were similar to international reports and inversely related to age at commencement of GH. First-year GV-for-age for BGHD patients was similar to international standards for idiopathic GHD. However, girls had an inferior response to boys when treatment commenced at <6 years of age. First-year GV-for-age for SSSG-ISS/FSS patients was less than ISS standards. Dose increments attenuated the first- to second-year decline in response to BGHD but marginally improved the responses for SSSG-ISS/FSS. CONCLUSIONS: The Australian auxology-based GH programme produces comparable responses to international programmes. A lower starting dose is offset by the initiation of treatment at younger ages. Incremental dosing does not appear optimal. A first-year dose of 6·4-6·9 mg/m(2)/week for GHD and 8·9 mg/m(2)/week for ISS with early commencement of GH treatment may be most efficacious.

An in vitro paradigm for diabetic cerebral oedema and its therapy: a critical role for taurine and water channels.

The pathophysiology of cerebral oedema (CE) in diabetic ketoacidosis (DKA) remains enigmatic. We investigated the role of the idiogenic osmol taurine and aquaporin channels in an in vitro model, the SH-SY5Y neuroblastoma cell line, by sequentially mimicking DKA-like hyperglycemia/hypertonicity and hypotonic fluid therapy. Exposure to DKA-like hyperosmolarity led to shrinkage, while hypotonic fluid exposure led to cell swelling and impaired viability. Low sodium compensated in part for elevated glucose, pointing to a critical role for overall osmolality. Taurine, was synthesized and retained intracellularly during DKA-like hypertonicity, and released during hypotonicity, in part mitigating neuronal swelling. Metabolic labeling showed that the rate of taurine release was inadequate to fully prevent neuronal swelling during hypotonic fluid therapy following DKA-like hypertonicity. Under these conditions, Aquaporin4 & 9 channels were respectively down and up-regulated. Our study provides further novel insights into molecular mechanisms contributing to CE in DKA and its therapy.