Perthes disease: a survey of management amongst members of the British Society for Children’s Orthopaedic Surgery (BSCOS)

The treatment of Legg-Calvé-Perthes disease remains controversial. The aim of this survey was to ascertain the current management strategies of this condition amongst UK paediatric orthopaedic surgeons, with particular regard to containment procedures in the fragmentation phase. Questionnaires were distributed at the January 2006 meeting of the British Society for Children’s Orthopaedic Surgery (BSCOS) and was posted to all absent members. The results showed a great deal of variability not only in the treatment of Perthes disease, but also in the decision-making processes. Consideration must now be given to a carefully constructed national multi-centre prospective randomised controlled study into the optimum management of this disease     

Power law analysis of the signal-averaged electrocardiogram for identification of patients with ventricular tachycardia: effect of bundle branch block.

Signal-averaged ECGs that use time-domain analysis are useful for the identification of patients at risk for ventricular tachycardia (VT). Bundle branch block (BBB) and other conduction defects reduce the value of this approach, but frequency-domain analysis has shown promise in such patients. The purpose of the present study was to examine a new frequency-domain approach to signal-averaged ECGs in patients with and without BBB: power law scaling (PLS). PLS was performed by plotting the power spectrum of the entire signal-averaged ECG on a plot of log power versus log frequency and determining the slope (beta) by least-squares regression. This method was studied in 346 patients. Results of discriminant analysis revealed better sensitivity, specificity, positive predictive value, negative predictive value, and percentage correctly predicted when this method was compared with time-domain indexes. A large proportion of the variance in PLS (19%) was found to be due to findings in patients with VT; whereas the best time-domain index, duration of the filtered QRS signal, explained only 6% of the variance in the group with VT. Mean levels of PLS (+/- standard deviation) were decreased for the group with VT (-3.55 +/- 0.95) as compared with the group without VT (-4.34 +/- 0.59; p < 0.001), suggesting a decrease in the time correlation of the signal. Thus this method of frequency-domain analysis of the signal-averaged ECG was useful in identifying patients with sustained VT despite the presence of significant conduction defects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Mouse limb muscle is determined in the absence of the earliest myogenic factor myf-5.

myf-5 is the only member of the MyoD family of myogenic regulatory genes to be expressed in the mouse embryo prior to muscle cell differentiation. We have used the developing limb as a model in which to follow the formation of peripheral muscle, to address the question of whether myogenic precursor cells are already present in the limb bud before expression of myf-5. The lacZ reporter gene has been introduced into the myf-5 gene by homologous recombination so that its expression is under the control of the endogenous myf-5 locus. beta-Galactosidase (beta-gal) coloration provides a sensitive assay for myf-5+ cells. Embryos were generated from embryonic stem cells carrying this mutation, and the appearance of beta-gal+ (myf-5+) cells was followed during limb development in vivo. Limb buds, at a stage when they are beta-gal-, were cultured in vitro. After several days, beta-gal+ cells accumulated in the premuscle mass. We conclude that determined muscle precursor cells in the limb bud do not initially express any member of the MyoD family. Furthermore, myogenic precursor cells in the somite, which, according to the avian model, migrate from the ventral/lateral edge of the dermomyotome to form peripheral muscle masses, are also negative for these factors.     

Prevention of endocarditis: communication between doctors and dentists.

Successful implementation of guidelines to prevent infective endocarditis (IE) depends upon the dental practitioner being aware of which of his patients are at risk. This was studied by sending a questionnaire to at risk patients and their dentists in the Grampian area. Of 145 respondents (53% response rate) with predisposing cardiac disorders, only 63 reported having seen their dentist in the past 2 years, although for dentate patients 47/61 had seen a dentist in the past 2 years. The dentists of 59 of these cases were then surveyed and replies received in 53 cases. Nineteen had no record of the patient having a cardiac disorder. In only 17 of the remaining cases was information on the cardiac disorder well enough recorded to warrant prophylaxis for at risk procedures. The dentist was usually told of the disorder only by the patient. Sixty-three per cent of dentists felt that communication between them and the patient's doctor was unsatisfactory. It is necessary to improve doctor/patient/dentist communication so that current recommendations on prophylaxis can be implemented to the full. This should be done through the patient's GP or consultant, who should communicate directly with the dentist. Details could also be inserted on warfarin cards and 'cardiac alert cards' expanded.     

In vivo and in vitro studies on the opioidergic control of the secretion of gonadotrophin-releasing hormone and luteinizing hormone in sexually immature and adult male rats.

In vivo and in vitro methods have been used to compare the effects of opioid receptor blockade on the functional activity of the hypothalamo-pituitary-gonadal axis in adult (200 g) and sexually immature (50 g) male rats. In the adult, a single injection of the mu-receptor antagonist, naloxone (500 micrograms/100 g body weight, s.c.), produced hypersecretions of luteinizing hormone (LH) and testosterone. Maximal serum concentrations of the two hormones were attained within 20 and 60 min respectively. In contrast, neither ICI 174864 (100 micrograms/100 g body weight, s.c.) nor MR2266 (150 micrograms/100 g body weight, s.c.), which block delta- and kappa-receptors respectively, stimulated pituitary-gonadal activity; indeed, like the saline vehicle, both tended to depress the serum LH concentration. The injection procedure was sufficient to activate the hypothalamo-pituitary-adrenal axis and, thus, the vehicle-treated controls exhibited significant increases in the plasma adrenocorticotrophin and serum corticosterone concentrations. These effects were enhanced by naloxone (500 micrograms/100 g body weight, s.c.) and by the kappa-opioid receptor (MR2266, 150 micrograms/100 g body weight, s.c.) but not by the delta-opioid receptor antagonist (ICI 174864, 30-100 micrograms/100 g body weight, s.c.). The increases in serum corticosterone and LH concentration induced by naloxone in adult rats were not apparent in the sexually immature (50 g) animals. To the contrary, in the young rats naloxone (250 and 500 micrograms/100 micrograms body weight, s.c.) attenuated, in a dose-dependent manner, the pronounced hypersecretion of corticosterone induced by the vehicle injection. The higher dose of the antagonist (500 micrograms/100 g body weight, s.c.) also overcame the significant reductions in serum LH evident 20 (p less than 0.05) and 40 (p less than 0.01) min after the saline injection but the lower dose (250 micrograms/100 g body weight, s.c.) was ineffective in this respect. In vitro, hypothalami from both adult and sexually immature rats responded to the addition of naloxone (10(-8)-10(-6) M) to the incubation medium with significant (p less than 0.01) concentration-dependent increases in the release of gonadotrophin-releasing hormone (GnRH). In contrast, ICI 174864 (10(-7)-10(-6) M) and MR2266 (10(-7)-10(-6) M) had little effect on the secretion of the releasing hormone by hypothalami from rats of either group although, at the highest concentration tested, MR2266 (10(-6) M) precipitated a small increase in GnRH release from hypothalami from adult rats.(ABSTRACT TRUNCATED AT 400 WORDS)     

Isoflurane Pretreatment Has Immediate and Delayed Protective Effects against Cytokine-induced Injury in Endothelial and Vascular Smooth Muscle Cells

Background: Volatile anesthetics have protective effects against cytokine-induced injury in endothelial and vascular smooth muscle cells. The authors hypothesized that isoflurane pretreatment may trigger immediate and delayed protection that is modulated by adenosine triphosphate-sensitive potassium channels.

Methods: Human and bovine endothelial cells and rat vascular smooth muscle cells were pretreated with isoflurane (1.5% for 30 min) and then exposed to cytokines (tumor necrosis factor-[alpha], interferon-[gamma], and interleukin-[beta]) for 72 h. Cytokine exposure was initiated immediately after isoflurane pretreatment or after a delay of 1-48 h. Cell survival and viability were evaluated by trypan blue exclusion and lactate dehydrogenase release. The role of mitochondrial and cell membrane adenosine triphosphate-sensitive potassium channels, or both, were evaluated with the antagonists 5-hydroxydecanoate, HMR-1098, or glybenclamide.

Results: Immediate isoflurane pretreatment was approximately 70% effective in increasing cell survival and prevented lactate dehydrogenase release in all cell lines. However, cellular protection was completely lost if the time between isoflurane and cytokine exposure was extended to 2-12 h, depending on the cell type. Delayed protection was equal to immediate protection when the interval was extended to 12-24 h, with protection being sustained at 48 h in human endothelial and rat vascular smooth muscle cells. The immediate and delayed protection was inhibited by glybenclamide and 5-hydroxydecanoate but not by HMR-1098, whereas diazoxide, a mitochondrial adenosine triphosphate-sensitive potassium channels agonist, mimicked the time course of isoflurane-induced immediate and delayed protection in all cell lines.     

On the Use of Paramagnetic Beads and Ferrofluids to Assess and Eliminate the Leukocytic Contribution to Oxygen Radical Generation by Human Sperm Suspensions

PROBLEM: To develop a methodology to determine a) the leukocytic contribution to reactive oxygen species generation by human sperm suspensions and b) the therapeutic value of removing these cellular contaminants. METHODS: Leukocytes were removed with paramagnetic beads or colloidal ferrofluids coated with anti-CD45 antibody. The sperm suspensions were monitored for oxidant generation by chemiluminescence, leukocyte contamination by immunocytochemistry, and fertilizing potential using zona-free hamster oocytes. RESULTS: Percoll®-prepared human sperm suspensions exhibited a competence for PMA-induced reactive oxygen species generation which was significantly correlated with leukocyte contamination. However, the purified spermatozoa remaining after paramagnetic bead treatment, also demonstrated an intrinsic capacity for PMA-responsive reactive oxygen species generation and, freed from the oxidative stress created by the leukocytes, exhibited a significantly enhanced capacity for sperm-oocyte fusion. CONCLUSIONS: Although human spermatozoa can generate reactive oxygen species, sperm function is inhibited by the additional oxidative stress created by contaminating leukocytes. Removal of these cells with paramagnetic beads enhances fertilizing potential.     

Andrology: Analysis of sperm movement in relation to the oxidative stress created by leukocytes in washed sperm preparations and seminal plasma

The addition of luminol to unprocessed semen samples resultedin the generation of chemiluminescent signals, the intensityof which was highly correlated with the level of leukocyte contamination.Despite the spontaneous oxidant-generating capacity of seminalleukocytes, no correlations were observed between leukocytecontamination and the fertility status of the subjects or anyaspect of the semen profile, including the motility of the spermatozoaor their performance in a hyaluronate penetration assay. Luminol-dependentchemiluminescence and leukocyte contamination were also correlatedin washed sperm suspensions prepared either by repeated centrifugationor on discontinuous Percoll gradients. However, in such spermsuspensions, the spontaneous generation of oxidants by contaminatingleukocytes (>2x10⁴ leukocytes/ml) was invariably associatedwith a decreased capacity for movement. Moreover, causativeassociations between leukocyte contamination, reactive oxygenspecies generation, lipid peroxidation and impaired sperm motilitywere revealed by experiments involving the selective additionor removal of activated leukocytes. From these observationswe can conclude that low concentrations of leukocytes are acommon feature of the human ejaculate and can impair sperm function,particularly in the absence of seminal plasma. These findingshave implications for our understanding of the importance ofleukocytospermia in defining the fertility of human spermatozoain vivo and in vitro.     

Evaluation of the Bacti-Lab streptococci culture systems for selective recovery and identification of group A streptococci.

Twenty-nine lots of Bacti-Lab streptococci culture plates containing nalidixic acid, neomycin, and amphotericin B were inoculated with 25 strains of group A, B, C, F, and G strepotocci, 13 strains of nonstrepotcoccal organisms representative of the throat flora, and 198 fresh clinical thorat specimens to determine the accuracy of the plates in identifying group A streptococci. With the Bacti-Lab test plates 98.87% of the beta-hemolytic streptococcal strains tested produced growth 95.51% yielding more than 50 colonies. Of the nonstreptococcal beta-hemolytic and non-beta-hemolytic organism tested, 79.54% were inhibited by the selective media. When bacitracin disks were used for presumptive identification group A streptococci from clinical thorat specimens, 12.00% false positive and 0.00% false negative results were obtained as measured by the direct flourescent-antibody and Lancefield grouping methods.