Benign intracranial hypertension and recombinant growth hormone therapy in Australia and New Zealand

Benign intracranial hypertension (BIH) is reported in three children from Australia and one from New Zealand, who were being treated with recombinant human growth hormone (rhGH). Three males and one female, aged between 10.5 and 14.2 y, developed intracranial hypertension within 2 weeks to 3 months of starting treatment. A national database, OZGROW, has been prospectively collecting data on all 3332 children treated with rhGH in Australia and New Zealand from January 1986 to 1996. The incidence of BIH in children treated with growth hormone (GH) is small, 1.2 per 1000 cases overall, but appears to be greater with biochemical GHD (<10IUml ^-1), i.e. 6.5/1000 (3 in 465 cases), relative risk 18.4, 95% confidence interval 1.9-176.1, than in all other children on the database. The incidence in patients with Turner's syndrome was 2.3/1000 (1 in 428 cases). No cases in patients with partial GHD (10–20 IUml ^-1) or chronic renal failure were identified. Possible causative mechanisms are discussed. The authors'practice is now to start GH replacement at less than the usual recommended dose of 14IUm-² week^-1 in those children considered to be at high risk of developing BIH. Ophthalmological evaluation is recommended for children before and during the first few months following commencement of rhGH therapy and is mandatory in the event of peripheral or facial oedema, persistent headaches, vomiting or visual symptoms. The absence of papilledema does not exclude the diagnosis.     

Humoral immunity to Malassezia furfur serovars A, B and C in patients with pityriasis versicolor, seborrheic dermatitis and controls

Abstract This study examined the humoral immune responses to Malassezia furfur serovars A, B and C of 10 patients with pityriasis versicolor, 10 patients with seborrheic dermatitis and 20 age- and sex-matched controls. A transferable solid-phase ELISA was used to determine titres of total Igs, IgM, IgA and IgG specific to M. furfur serovars A, B and C. The results demonstrated that patients with seborrheic dermatitis had a significantly higher litre of total Igs to serovar A than patients with pityriasis versicolor; and that patients with seborrheic dermatitis had a significantly higher litre of IgA to serovar C than patients with pityriasis versicolor. The litres of total Igs for controls and patienls with seborrheic dermatitis were significantly lower to serovar B than to serovar C. A modified TSP ELISA was used to determine the titres of the IgG subclasses. Titres of IgG _1,3,4 to serovar B were significantly higher in seborrheic dermatitis patients than pityriasis versicolor patients and litres of IgG₃, to serovar A were significantly higher in seborrheic dermatitis patients than pityriasis versicolor patients. However, despite the differences between the patient groups, none of these results was significantly different to those of controls. Thus, this study did not demonstrate any differences in humoral immunity of patients suffering from Malassezia-associated dermatoses when compared to normal controls. These results may suggest that the humoral immune response to M. furfur is not related to the pathogenesis of Malassezia-associated dermatoses, but simply to the carriage of M. furfur on the skin.     

Long-term wear of ceramic matrix composite materials for hip prostheses under severe swing phase microseparation

The purpose of this study was to evaluate the long-term wear performance of alumina matrix composite (AMC) heads against alumina matrix composite inserts and alumina matrix composite heads against alumina (Al) inserts with the use of a hip-joint simulator incorporating severe swing phase joint microseparation. The wear of AMC on Al produced an average wear rate of 0.61 mm3/million cycles over the 5-million-cycle test duration. The wear of AMC on AMC produced an average wear rate of 0.16 mm3/million cycles over the 5-million-cycle test duration. Both the AMC on alumina and AMC on AMC produced significantly lower wear than previously tested HIPed alumina, where an average wear rate of 1.84 mm3/million cycles was reported over 5 million cycles. The wear mechanisms and wear debris of AMC on AMC and AMC on Al were similar to those observed in previous alumina retrieval studies with stripe wear caused by intragranular fracture and wear debris consisting of predominantly uniform 10-20-nm-sized particles and a few irregular particles up to 3 microm in size.     

Quantitative analysis of wear and wear debris from metal-on-metal hip prostheses tested in a physiological hip joint simulator

Osteolysis and loosening of artificial joints caused by UHMWPE wear debris has prompted renewed interest in metal-on-metal (MOM) hip prostheses. This study investigated the wear and wear debris morphology generated by MOM prostheses in a physiological anatomical hip simulator for different carbon content cobalt chrome alloys. The low carbon pairings demonstrated significantly higher "bedding in" and steady state wear rates than the mixed and high carbon pairings. The in vitro wear rates reported here were up to one or two orders of magnitude lower than the clinical wear rates for first-generation MOM hip prostheses. Two methods for characterising the metal wear debris were developed, involving digestion, scanning electron microscopy and transmission electron microscopy. The metal wear particles characterised by the two methods were similar in size, 25-36 nm, and comparable to particles isolated from periprosthetic tissues from first and second-generation MOM hip prostheses. Due to the small size of the metal particles, the number of particles generated per year for MOM prostheses in vitro was estimated to be up to 100 times higher than the number of polyethylene particles generated per year in vivo. The volumetric wear rates were affected by the carbon content of the cobalt chrome alloy and the material combinations used. However, particle size and morphology was not affected by method of particle characterisation, the carbon content of the alloy or material combination.     

Comparison of the response of primary human peripheral blood mononuclear phagocytes from different donors to challenge with model polyethylene particles of known size and dose

The response of primary human peripheral blood mononuclear phagocytes to challenge with polyethylene particles of known size and dose was evaluated. Particles with mean sizes of 0.21, 0.49, 4.3, 7.2, and 88 microm were co-cultured with cells for 24 h prior to the assessment of cell viability and production of the osteolytic mediators IL-1beta, IL-6, TNFalpha, GM-CSF and PGE2. All particle fractions were evaluated at particle volume (microm3) to cell number ratios of 10:1 and 100:1 which were previously identified as being the most biologically active and clinically relevant. The heterogeneity of human individuals was clearly evident both in the profile and the magnitude of the response of the donors evaluated in this study (the response of donor 5 being 2- to 15-fold lower than that of the other donors). Only the sub-micrometre particles stimulated significantly enhanced cytokine secretion at the ratios tested: mean particle sizes of 0.49 and 0.21 microm being the most biologically active. Macrophages stimulated with particles outside this size range produced considerably lower levels of mediator. These results compared favourably with the results of earlier studies, which demonstrated that particles within the phagocytosable size range (0.1-10 microm) were the most biologically active. These results, therefore, confirm earlier findings and suggest that the size and volume of polyethylene particles are critical factors in macrophage activation. Furthermore, they suggest that the heterogeneity of human individuals may be another important factor in determining implant life and could provide the basis for a valuable diagnostic tool to identify those patients most at risk of implant loosening.