Imaging recurrent parosteal osteosarcoma

The aim of this study was to document the imaging features of recurrent parosteal osteosarcoma. The clinical and imaging records of 33 patients with a parosteal osteosarcoma referred to an orthopaedic oncology service over a 17-year period were retrospectively reviewed. The mode of identification of locally recurrent tumour was noted, together with the management and clinical outcome. Five patients developed a local recurrence of their parosteal osteosarcoma ranging from 6 months to 10 years after initial surgery. In 4 patients the recurrence was first suspected clinically due to the development of a mass. In the fifth patient recurrence was first detected on routine follow-up radiography. In 4 patients the recurrence could be identified on radiography as a mineralized mass. All the recurrences were readily identified on MR imaging, despite artefacts from prostheses. The recurrences were also evident in the 3 cases in which bone scintigraphy was performed. Local recurrence of parosteal osteosarcoma is adequately detected with a combination of clinical examination and conventional radiography. MR imaging is required to stage local recurrence or where radiography has failed to confirm clinically suspected recurrence. The routine use of MR imaging to follow-up patients is of doubtful value because of the frequently long time between initial surgery and relapse. Received: 23 June 2000 Revised: 7 August 2000 Accepted: 9 August 2000     

BAPS prize-1999: Lung growth induced by prenatal tracheal occlusion and its modifying factors: a study in the rat model of congenital diaphragmatic hernia

BACKGROUND/PURPOSE: Prenatal tracheal occlusion (TO) has been shown to accelerate lung growth in animal models and models of pulmonary hypoplasia. However, these models may not mimic early events in human congenital diaphragmatic hernia (CDH). The authors previously have developed a model of TO in the rat. The purpose of this study was to apply this technique to characterize TO-induced lung growth in the early onset nitrofen-induced model of CDH, and to address the clinically important questions of the effect of timing of TO and maternal infusion of terbutaline on TO-induced lung growth. METHODS: Left-sided CDH was induced in the fetuses of time-dated pregnant Sprague-Dawley rats by feeding 100 mg of nitrofen on day 9 of gestation. TO was performed via maternal laparotomy and hysterotomy at 19 days' gestation. At harvest (21.5 days' gestation), lungs from nitrofen-exposed fetuses without CDH (non-CDH), with CDH (CDH), and with CDH and TO (CDH-TO) were compared by analysis of wet and dry weight, DNA and protein content, and stereologic morphometry. A second study was performed to assess relative lung growth achieved by equal intervals of TO after "early" (19 days) versus "late" (20 days) gestational TO. Finally, the effect of maternal infusion of terbutaline, a commonly used tocolytic for fetal surgery, on TO-induced lung growth was analyzed. RESULTS: Analysis of lung growth showed consistent and significant lung growth in CDH-TO lungs. Lung growth after TO was proliferative and characterized by an increase in parenchymal volume as manifest by increased total saccular number and surface area and radial saccular count. Although visceral reduction was partially achieved, herniated liver was reduced incompletely. The majority of lung growth occurred during the latter half of the TO period. Early gestational age at TO and maternal terbutaline administration adversely influenced lung growth in CDH-TO fetuses. CONCLUSIONS: Prenatal TO induces dramatic lung growth in the early onset, nitrofen-induced rat model of CDH. TO is more effective later in gestation presumably because of the advanced stage of lung development and lung fluid production. This effect could be counterbalanced by the use of beta-mimetic tocolytic, which inhibits fetal lung fluid production late in gestation. Multiple factors including fetal lung fluid production and absorption, pharmacologic agents, space-occupying herniated viscera, and timing and duration of TO may be important clinical variables. The development of the rat model should facilitate further studies into the cellular and molecular mechanisms responsible for TO-induced lung growth.     

Glucocorticoid inhibition of neuropathic hyperalgesia and spinal Fos expression

Glucocorticoids are used to treat patients suffering from neuropathic pain and complex regional pain syndromes (CRPS). Previously we found that once-daily injections of the glucocorticoid methylprednisolone had no antihyperalgesic effect in the rat sciatic nerve transection model for CRPS, but on the basis of CRPS clinical data, we hypothesized that a continuous infusion of methylprednisolone might prove effective. We further postulated that the antihyperalgesic effects of glucocorticoids were mediated by the inhibition of spinal neuron hyperactivity and by the depletion of substance P or its NK(1) receptor. This study tested the effects of continuously infused methylprednisolone in sciatic nerve-transected rats. Continuous infusion of methylprednisolone (3 mg. kg(-1). d(-1) for 21 days), started after the development of neuropathic hyperalgesia, reversed both heat and mechanical hyperalgesia over 2 wk, and this effect persisted for at least 1 wk after discontinuing methylprednisolone. In addition, continuous methylprednisolone infusion partially reversed nerve injury-evoked Fos expression in the dorsal horns, suggesting that glucocorticoids can inhibit the spinal neuron hyperactivity induced by chronic sciatic nerve transection. Finally, no changes were observed in spinal substance P or NK(1) immunoreactivity after chronic methylprednisolone infusion, suggesting that the depletion of this neuropeptide or its receptor does not contribute to the antihyperalgesic actions of glucocorticoids.     

Sedative but not analgesic alpha2 agonist tolerance is blocked by NMDA receptor and nitric oxide synthase inhibitors

BACKGROUND: Studies show that the sedative and analgesic effects of alpha2 adrenergic agonists decrease over time, which is a form of synaptic plasticity referred to as tolerance. Because both the N-methyl-D-aspartate (NMDA) receptor complex and nitric oxide synthase are pivotal for some forms of synaptic plasticity, their role in tolerance to the hypnotic and analgesic effects of alpha2 agonists was investigated. METHODS: After institutional approval, rats were made tolerant to the hypnotic or analgesic action of an alpha2 agonist, dexmedetomidine. The hypnotic response to dexmedetomidine was assessed by the duration of loss of righting reflex, and the analgesic response to dexmedetomidine was assessed by the tail-flick assay. In separate cohorts, either the NMDA receptors or nitric oxide synthase was antagonized by coadministration of MK-801, ketamine, or NO2-arginine, respectively, during induction of tolerance. In a separate series of experiments, after tolerance was induced, the hypnotic and analgesic responses to dexmedetomidine were assessed in the presence of acutely administered MK-801 or NO2-arginine. RESULTS: Induction of tolerance to the hypnotic effect of dexmedetomidine is blocked by coadministration of MK-801, ketamine, and NO2-arginine. However, after tolerance developed, acute administration of MK-801, ketamine, or NO2-arginine did not prevent the expression of tolerance. Coadministration of MK-801 or NO2-arginine neither prevents the development nor reverses the expression of tolerance to the analgesic action of dexmedetomidine. CONCLUSION: The underlying processes responsible for the development of tolerance to the hypnotic and analgesic actions of systemically administered alpha2 agonists were different, with only the sedative tolerance involving the NMDA receptor and nitric oxide synthase system.     

Postpneumonectomy aortic arch mycotic aneurysm

A 31-year-old woman who had undergone left pneumonectomy for a tuberculosis-destroyed left lung 3 years previously presented in respiratory distress after a pregnancy complicated by preeclampsia and aspiration pneumonia. Investigation revealed a large aortic arch aneurysm as well as a filling defect in the descending thoracic aortic lumen. Emergency aortic arch reconstruction was performed for a massive pseudoaneurysm or contained rupture filling the entire postpneumonectomy space. Pathologic and microbiological examination demonstrated Aspergillus fumigatus and active inflammation.     

Determining the best method for first-line assessment of neonatal blood glucose levels

OBJECTIVE: To evaluate and compare the accuracy and performance of two electrochemical glucose meters. To determine the user acceptability of these glucose meters and the ABL 620 Blood Gas Analyser (Radiometer, Copenhagen, Denmark) with an electrochemical glucose oxidase electrode for use in a Level 2 special care baby unit. METHODOLOGY: A total of 108 blood samples were collected from 47 babies at risk for hypoglycaemia. The blood glucose level was measured with two glucose meters, the Advantage Glucose Meter (Roche Diagnostics, Castle Hill, Australia) and the Precision-G Blood Glucose Testing System (Medisense, Melbourne, Australia), and the true blood glucose (TBG) measured with the ABL 620 blood gas analyser. Results from the glucose meters were compared with the TBG (as a percentage of the TBG). RESULTS: The mean (SD) percentage difference between the Advantage Glucose Meter and TBG was 4.5% (12. 5), and Precision-G Glucose Meter and TBG was 15.4% (12.4). The sample haematocrit did not significantly influence the glucose meter/TBG differences. There was an overall preference by the nursing staff for the Advantage Glucose Meter. CONCLUSIONS: The Advantage Glucose Meter was significantly more accurate than the Precision-G with similar precision. It was the preferred method of screening for neonatal hypoglycaemia.     

The effect of draw-up volume on the accuracy of electrolyte measurements from neonatal arterial lines

OBJECTIVES: Contamination by infusate of blood samples withdrawn from arterial lines has been recognized but not well documented for neonates. The aim of this study was to investigate, using in vitro and in vivo studies, the effects of different draw-up volumes (withdrawn from the line prior to the sample being taken) on the concentration of sodium. METHODS: In-vitro study: The tip of an umbilical artery catheter (dead space 0.6 mL), infused with half normal saline containing 1 unit/mL of heparin was placed in a beaker of normal saline. The line was flushed with 1 mL of this infusate just before each sample was taken. Volumes from 0.5 mL to 2.0 mL of infusate/normal saline were withdrawn in 0.1 mL increments from a three-way tap and discarded. A sample was then taken from the line into a blood gas syringe for analysis of the sodium concentration by the 860 Blood Gas Analyzer (Chiron Diagnostics, Bayer, Scoresby). Control samples were taken from the beaker. In-vivo study: A 22 gauge intravenous catheter was inserted into a vein of an adult male volunteer. The dead space was also 0.6 mL. The line was flushed with 5 mL of half-normal saline immediately before sampling. Draw-up volumes of 0.6, 0.9, 1.3, and 1.6 mL were withdrawn and discarded. 10 mL was used as a control. A 0.5-mL blood sample was then taken and the electrolyte concentrations analysed immediately. RESULTS: In-vitro: A minimum draw-up volume of 1.3 mL was required before the sodium concentration was not significantly different from the control samples. In-vivo: A minimum draw-up volume of 1.6 mL was required before the sodium concentration was not significantly different from the control samples. There were similar trends in the effect of draw-up volume for glucose, calcium, potassium, chloride and lactate. CONCLUSION:: A minimum volume of 1.6 mL should be withdrawn from neonatal arterial lines (dead space 0.6 mL) before taking blood for analysis.     

Growth and nutrition of Hong Kong children aged 0-7 years

OBJECTIVE: To study the early dietary practices in relation to growth of Hong Kong children from birth to 7 years. METHODOLOGY: One hundred and seventy-three full-term Hong Kong Chinese babies were recruited at birth and were followed up for anthropometric measurements using standardized methods and dietary assessment using a combination of dietary history, 24 h recall and food frequency. At 7 years, 125 children remained in the study. RESULTS: Mean (SD) birthweight was 3.3 (0.38) kg for boys and 3.1 (0.38) kg for girls. Mean (SD) weight at 7 years was 22.4 (4.2) kg for boys and 21.1 (3.7) kg for girls, and mean (SD) height was 120.3 (4.8) cm for boys and 119.8 (5.1) cm for girls. Hong Kong children were lighter and shorter than Australian children and the National Centre for Health Statistics (NCHS) references, but the magnitude is less than one standard deviation score. Mean weight and height of Hong Kong children were lower compared to Caucasian and Beijing children, with more obvious differences between 1 and 5 years. At 1 year, mean (SD) daily energy intake was 98 (24) kcal/kg/day for boys and 100 (26) kcal/kg/day for girls. By 7 years, it decreased to 82 (18) kcal/kg/day for boys and 73 (22) kcal/kg/day for girls. Between 2 to 4 years of age the energy intake of studied children were slightly lower than the Australian and Finnish children, but the protein intake was higher. Percentage of fat contributing to total daily energy intake was lower throughout at a level of 30%. Such differences in diet reflect a lower consumption of milk fat, higher consumption of meat and lower level of physical activity in Hong Kong children. Intakes of calcium, iron and vitamin C all reached 60% or above of US recommended daily allowance. CONCLUSIONS: The smaller body build of Chinese compared to Caucasians cannot be explained by dietary differences. The diet of Hong Kong children is changing to one which is more Westernized with a higher consumption of animal products.