Christine Rodda

Antibodies to parathyroid hormone-related protein lower serum calcium in athymic mouse models of malignancy-associated hypercalcemia due to human tumors.

A parathyroid hormone-related protein (PTHrP) has recently been isolated from tumors associated with hypercalcemia. In the present study, we tested the effects of neutralizing antisera to the PTHrP on serum calcium and urine cAMP in two animal models of malignancy-associated hypercalcemia. The animal models consisted of (a) a human squamous cell lung cancer and (b) a human laryngeal cancer, both serially carried in athymic mice. The antisera specifically reduced the elevated serum calcium and urinary cAMP levels in the tumor-bearing animals. We conclude that PTHrP plays a major role in the pathogenesis of malignancy-associated hypercalcemia.

The prevalence of polycystic ovaries in patients with congenital adrenal hyperplasia and their close relatives

Seventy‐seven female patients (36 adults and 41 children aged under 16 years) with congenital adrenal hyperplasia (CAH) were assessed using pelvic ultrasound, as well as with standard endocrine tests and HLA typing. Forty‐six close female relatives were also tested for ovarian morphology using ultrasound after assessment of their heterozygous state using HLA typing. The association of CAH with ultrasonically detected polycystic ovaries (PCO) was confirmed in 30/36(83%) adult patients, 4/10 (40%) postpubertal girls and 1/31 (3%) pre and peripubertal girls: in all, 35/46 (76%) postmenarcheal patients. Six out of nine (67%>) pre‐menopausal mothers of patients with PCO, and 8/10 (80%) sisters of patients with PCO also had PCO. The proportions of both CAH patients and heterozygote subjects with PCO were significantly greater than that found in a normal population (P<00.001). The finding, however, of two homozygous non‐CAH‐affected adult sisters with PCO and, conversely, of 10 heterozygous adult relatives and of 12 postmenarcheal CAH patients with normal ovaries, indicates that the ovarian morphological change may be independent of the adrenal lesion.

Use of bisphosphonate therapy for osteoporosis in childhood and adolescence

Abstract:  Congenital and acquired forms of osteoporosis in childhood and adolescence can result in morbidity from fracture and pain in childhood, and place an individual at significant risk for problems in adult life. A range of therapies exist for the prevention and treatment of osteoporosis, including optimization of daily calcium intake, adequate vitamin D status, weight‐bearing exercise, treatment with sex steroids where delayed puberty is a problem and, more recently, use of bisphosphonate therapy. Intravenous pamidronate therapy (a bisphosphonate) has been shown to reduce fractures and improve bone density in children with osteogenesis imperfecta, and might prove to be of benefit in other osteoporotic conditions in childhood. However, a number of issues regarding the optimal use of bisphosphonate therapy in children and adolescents remain to be resolved, including total annual dose and frequency and duration of administration. Bisphosphonate therapy should, therefore, be used only in the context of a well‐run clinical programme with specialist knowledge in the management of osteopenic disorders in childhood.

Identification of 70 calcium-sensing receptor mutations in hyper- and hypo-calcaemic patients: evidence for clustering of extracellular domain mutations at calcium-binding sites

The calcium-sensing receptor (CaSR) is a G-protein-coupled receptor that has an extracellular bilobed venus flytrap domain (VFTD) predicted to contain five calcium (Ca(2+))-binding sites. To elucidate the structure-function relationships of the VFTD, we investigated 294 unrelated probands with familial hypocalciuric hypercalcaemia (FHH), neonatal severe primary hyperparathyroidism (NSHPT) or autosomal dominant hypocalcaemic hypercalciuria (ADHH) for CaSR mutations and performed in vitro functional expression studies and three-dimensional modelling of mutations involving the VFTD. A total of 70 different CaSR mutations were identified: 35 in FHH, 10 in NSHPT and 25 in ADHH patients. Furthermore, a CaSR variant (Glu250Lys) was identified in FHH and ADHH probands and demonstrated to represent a functionally neutral polymorphism. NSHPT was associated with a large proportion of truncating CaSR mutations that occurred in the homozygous or compound heterozygous state. Thirty-four VFTD missense mutations were identified, and 18 mutations were located within 10 Å of one or more of the predicted Ca(2+)-binding sites, particularly at the VFTD cleft, which is the principal site of Ca(2+) binding. Mutations of residues 173 and 221, which are located at the entrance to the VFTD cleft binding site, were associated with both receptor activation (Leu173Phe and Pro221Leu) and inactivation (Leu173Pro and Pro221Gln), thereby highlighting the importance of these residues for entry and binding of Ca(2+) by the CaSR. Thus, these studies of disease-associated CaSR mutations have further elucidated the role of the VFTD cleft region in Ca(2+) binding and the function of the CaSR.

Vitamin D and health in pregnancy, infants, children and adolescents in Australia and New Zealand: a position statement.

The recommended level for serum 25‐hydroxyvitamin D (25(OH)D) in infants, children, adolescents and during pregnancy and lactation is ≥ 50 nmol/L. This level may need to be 10–20 nmol/L higher at the end of summer to maintain levels ≥ 50 nmol/L over winter and spring. Sunlight is the most important source of vitamin D. The US recommended dietary allowance for vitamin D is 600 IU daily in children aged over 12 months and during pregnancy and lactation, assuming minimal sun exposure. Risk factors for low vitamin D are: lack of skin exposure to sunlight, dark skin, southerly latitude, conditions affecting vitamin D metabolism and storage (including obesity) and, for infants, being born to a mother with low vitamin D and exclusive breastfeeding combined with at least one other risk factor. Targeted measurement of 25(OH)D levels is recommended for infants, children and adolescents with at least one risk factor for low vitamin D and for pregnant women with at least one risk factor for low vitamin D at the first antenatal visit. Vitamin D deficiency can be treated with daily low‐dose vitamin D supplements, although barriers to adherence have been identified. High‐dose intermittent vitamin D can be used in children and adolescents. Treatment should be paired with health education and advice about sensible sun exposure. Infants at risk of low vitamin D should be supplemented with 400 IU vitamin D3 daily for at least the first year of life. There is increasing evidence of an association between low vitamin D and a range of non‐bone health outcomes, however there is a lack of data from robust randomised controlled trials of vitamin D supplementation.

Treatment of growth-hormone deficiency with growth-hormone-releasing hormone

18 prepubertal growth-hormone (GH)-deficient children were treated with twice-daily subcutaneous injections of a growth-hormone-releasing hormone analogue, GHRH (1-29) NH2. In 12 of the children the height velocity rose on GHRH treatment, and 8 were judged to have shown a worthwhile response to therapy in that their height velocities during the first 6 months of treatment increased by greater than 2 cm/yr (range 2.7-11.2 cm/yr). These 8 children have now been treated for 6 to 18 months and their increase in height velocity has been maintained. In the 14 patients who had previously received human GH (hGH) height velocity on hGH correlated with that on GHRH. 4 of these patients showed growth deceleration with GHRH, for unknown reasons. A pretreatment peak serum GH response of above 30 mU/l during an intravenous GHRH test was predictive of a good growth response to GHRH but a lower peak did not preclude a growth response. There was no consistent evidence of a priming or desensitisation effect of therapy on the GH responses to GHRH. Although anti-GHRH antibodies developed in 14 patients, these did not seem to have adverse effects on either growth or the GH responses to GHRH. GHRH (1-29) NH2 therapy is an alternative to conventional hGH in the treatment of some GH-deficient children. Ideal dose regimens need to be established.

Adrenal suppression from high-dose inhaled fluticasone propionate in children with asthma

and bacterial infiltration of the injured tissue. Finally, there is an endocrine or late phase characterised by proliferation with endothelium and vascular wall modelling (angiogenesis), which, in the case of healing, involves tissular regeneration or wound healing by scar formation [2–4]. Therefore, in an early or nervous phase, the nutrition of the injured tissue would be produced by diffusion (oedema), a mechanism with low energetic requirement that does not require oxygen (ischemia) or that is not correctly used (synthesis of reactive oxygen species (ROS)). Products derived from the degradation of macromolecules by the ROS action can constitute substrates that reach the cells by diffusion. In the intermediate or immune phase, the nutrition could be mediated by the inflammatory cells because both the neutrophils, as well as the macrophages, have a large capacity for intracellular (phagocytosis of debris) and extracellular (release of enzymes) digestion [5, 6]. Complex proteins, such as enzymes and debris, can be important sources of fermentation [7]. These inflammatory cells respond with respiratory burst and release high concentrations of superoxide anion radical, hydroxyl radical, hypochlorus acid, hypobromite and hydrogen peroxide [1]. The lymphatic circulation could predominate in these phases of the inflammation in detriment of the blood circulation. Finally, in the late or endocrine phase, blood circulation is involved in the nutrition [5, 6]. Angiogenesis makes it possible to acquire a capillary network that is specialised in supplying oxygen and substrates to cells, which, in turn, use them through oxidative metabolism [6, 8], thus producing regeneration. However, the wounds heal by scar formation, a process in which the fibroblasts, due to their phenotypic plasticity [9], could become intermediary cells of the epithelial nutrition. The deficient capacity of the fibroblasts for this trophic function could explain the defective quality of the epithelium obtained. Phases that are similar to the above-mentioned ones are commonly described in airway asthmatic inflammation [1, 9]. In this way, reactive oxygen species hyperproduction, whether by revascularisation or by reactive oxygen species release by the inflammatory cells during the respiratory burst, could represent primitive trophic mechanisms, which are used by the injured tissue when the use of oxygen by oxidative phosphorylation is not possible. More useful energy (adenosine triphosphate) can be generated through this latter pathway and it is a more elaborated trophic mechanism.This cross-sectional study was designed to examine the prevalence of adrenocortical suppression in children with asthma treated with high-dose inhaled fluticasone propionate (FP). Children and adolescents (n=50) with asthma, treated with inhaled FP at a dose of > or = 1,000 mg a day for > or = 6 months, were enrolled. Early morning serum cortisol was performed. Subjects with a serum cortisol of < 400 nmol x L(-1) had a tetracosactrin stimulation test. Fifty subjects of mean age 13.1 yrs were treated with a mean dose of 924.7 microg x m(-2) x day(-1) FP for a mean duration of 2 yrs. Of the 50 subjects, 36 (72%) had serum cortisol levels of < 400 nmol x L(-1) and underwent tetracosactrin stimulation test. Of these, 6 (17%) demonstrated a less than two-fold increase in serum cortisol from baseline and peak cortisol level of < or = 550 nmol x L(-1) at 30 or 60 min poststimulation. There was a significant negative correlation between the dose of FP x m(-2) and stimulated peak cortisol level. Biochemical evidence of adrenocortical insufficiency was demonstrated in 12% of the subjects, indicating that high-dose fluticasone propionate use may be associated with dose-dependent adrenocortical suppression.

Incidence of vitamin D deficiency rickets among Australian children: an Australian Paediatric surveillance unit study

Objective: To determine the incidence of and factors associated with vitamin D deficiency rickets in Australian children.

Proinsulin-Specific, HLA-DQ8, and HLA-DQ8-Transdimer–Restricted CD4+ T Cells Infiltrate Islets in Type 1 Diabetes

Type 1 diabetes (T1D) develops when insulin-secreting β-cells, found in the pancreatic islets of Langerhans, are destroyed by infiltrating T cells. How human T cells recognize β-cell-derived antigens remains unclear. Genetic studies have shown that HLA and insulin alleles are the most strongly associated with risk of T1D. These long-standing observations implicate CD4+ T-cell responses against (pro)insulin in the pathogenesis of T1D. To dissect the autoimmune T-cell response against human β-cells, we isolated and characterized 53 CD4+ T-cell clones from within the residual pancreatic islets of a deceased organ donor who had T1D. These 53 clones expressed 47 unique clonotypes, 8 of which encoded proinsulin-specific T-cell receptors. On an individual clone basis, 14 of 53 CD4+ T-cell clones (26%) recognized 6 distinct but overlapping epitopes in the C-peptide of proinsulin. These clones recognized C-peptide epitopes presented by HLA-DQ8 and, notably, HLA-DQ8 transdimers that form in HLA-DQ2/-DQ8 heterozygous individuals. Responses to these epitopes were detected in the peripheral blood mononuclear cells of some people with recent-onset T1D but not in HLA-matched control subjects. Hence, proinsulin-specific, HLA-DQ8, and HLA-DQ8-transdimer–restricted CD4+ T cells are strongly implicated in the autoimmune pathogenesis of human T1D.

Bone mineral density in prepubertal asthmatics receiving corticosteroid treatment

Objective: To examine whether bone mass is reduced in prepubertal, asthmatics receiving high doses of inhaled corticosteroids.