Administered radiopharmaceutical doses in children: a survey of 13 pediatric hospitals in North America.

Universally applied standards for administering radiopharmaceutical doses in children do not presently exist. Hence, pediatric radiopharmaceutical dosimetry varies considerably from institution to institution and is generally based on the recommended adult dose adjusted for body mass. METHODS: We surveyed 13 pediatric hospitals in North America to obtain objective data on dosimetry practices for 16 pediatric nuclear medicine examinations, including the minimum total radiopharmaceutical administered dose per examination, the total administered dose based on body mass, and maximum total doses in children. RESULTS: The reported administered doses of radiopharmaceuticals to children vary over a relatively large range, especially with respect to minimum total administered doses. CONCLUSION: This survey has identified a broad range of administered doses directly leading to variability in radiation-absorbed doses to patients. The nuclear medicine community should develop pediatric standards for radiopharmaceutical administered doses and reduce radiation exposure in children, such as through the use of modern software reconstruction techniques.     

Standardization and quantification of radionuclide solid gastric-emptying studies.

The purposes of this investigation were to standardize and validate a simple quantitative method for performing radionuclide solid gastric emptying that can be used for any dual-head gamma-camera and to establish reference values. METHODS: After eating a solid meal (egg sandwich) labeled with a radionuclide, 20 healthy volunteers (9 male, 11 female) underwent a 90-min gastric-emptying study performed with a triple-head gamma-camera. Two sets of 3 simultaneous projections were acquired sequentially for 30 s each: anterior, right posterior oblique (RPO), left posterior oblique (LPO), posterior, left anterior oblique (LAO), and right anterior oblique (RAO), and this sequence was repeated continuously for 90 min. Time-activity curves were generated using a gastric region of interest for each of the views as well as the conjugate-view geometric mean (GM) data for the anterior/posterior, LAO/RPO, and RAO/LPO combinations. Quantitative parameters were determined: percentage gastric emptying (%GE) at 90 min, half-time (min) based on an exponential fit, and clearance rate (%/min) based on a linear fit. Reference values were determined on the basis of a 95% confidence interval of the t distribution. The results were statistically analyzed and compared. RESULTS: The %GE reference values were greater for the anterior/posterior GM (>or=33%) than for the LAO (>or=31%) and anterior (>or=30%) GMs. The 3 %GE GM methods, the 3 exponential-fit GM methods, and the 3 linear-fit GM methods had high correlation coefficients (r >or= 0.874), and with only a single exception, there was no statistical difference among them. The LAO method and LAO/RPO GM mean method correlated strongly (r = 0.900) and had similar mean values (52% vs. 51%) and reference values (29% vs. 30%). All 3 methods of GM quantification also correlated strongly, and there was no significant difference among them. CONCLUSION: We have described and validated a simple method for radionuclide solid gastric emptying that can be used with a dual-head gamma-camera. We recommend the anterior/posterior GM method and have established reference values (>or=33%).     

Calculation of a gallbladder ejection fraction: advantage of continuous sincalide infusion over the three-minute infusion method.

The purpose of this study was to investigate alternative methods of infusing sincalide for calculation of a gallbladder ejection fraction (GBEF) during cholescintigraphy (5 mCi 99mTc-mebrofenin). After gallbladder filling, three methods of infusion were compared in 23 normal volunteers: (1) 0.02 microgram/kg as a 3-min infusion, (2) 0.02 microgram/kg as a 30-min infusion, and (3) 0.01 microgram/kg as a 30-min infusion (14 subjects), all performed on separate days. With the 3-min infusion, the emptying pattern was usually exponential and completed in 15 min. The mean (GBEF) was 52% +/- 26% at 20 min and 56% +/- 27% at 30 min (range 0%-100%). GBEFs were less than 35% in six subjects and 35%-38% in four. Side effects were noted by 11/23 subjects. With the slow infusions, emptying was linear; no side effects were noted. With 0.02 microgram/kg, the mean GBEF was 50% +/- 27% at 20 min and 70% +/- 22% at 30 min (range 26%-95%). Similar results were seen with 0.01 microgram/kg, but the data were more limited. The 30-min infusion had a higher normalcy rate than the 3-min method (91% versus 74%). Females had significantly lower GBEFs than males (p less than 0.05%). We conclude that the slow infusion method is preferable; it is more physiological, results in more complete emptying, has no side effects, has less normal variability, and should improve the specificity of this test. The lower mean female GBEF may have pathophysiological significance.     

Cardiology

This article describes recent developments in cardiology and cardiovascular disease that are likely to be relevant to primary healthcare professionals and their patients. The following subject areas are covered: Primary prevention: recent developments in pharmaco-logical interventions, drug interactions, and drugs that are likely to cause harm; cardiovascular risk estimation and shared decision making with patients; and new developments in 24-hour ambulatory blood pressure monitoring. Secondary prevention: new models of care, including nurse-led care for the provision of hypertension and secondary prevention clinics; new drugs for the treatment of angina and myocardial infarction; ambulatory electrocardiography for the diagnosis of arrhythmias in primary care; and new developments in the treatment of atrial fibrillation - direct thrombin inhibitors and implantable devices. Tertiary prevention: recent developments in cardiac rehabilitation; recent evidence concerning revascularisation procedures and appropriateness criteria for referral; and implantable defibrillators.     

Saccadic trajectory in Huntington's disease.

Trajectories of saccadic eye movements can be modulated by the presence of a competing visual distractor. It is proposed that the superior colliculus (SC) controls the initial deviation through competitive lateral interactions. Given the ramifications of connections between basal ganglia (BG) thalamo-cortical circuitry and the SC, it was anticipated that this modulation would be differentially effected in those with Huntington's disease, which in its early stages is primarily a disorder of the BG. Horizontal deviation was determined for exogenously driven and endogenously driven vertical saccades in the presence of peripheral distractors. For neurologically healthy participants, the initial trajectories of both saccade types curved away from distractor locations, as predicted. However, for HD participants exogenous saccades consistently deviated leftwards, irrespective of distractor location. Endogenous saccades also revealed anomalous horizontal deviation, with significant leftward deviation evident for saccades directed upward and significant rightward deviation for saccades directed downward. Further, both groups generated a comparable proportion of erroneous responses to distractor stimuli, but only neurologically healthy participants demonstrated a response time advantage for compatible target/distractor presentation. These results suggest anomalous regulation of distractor-related activity in HD.     

Treatment of ischemic leg ulcers with pentoxifylline: a case report and theoretical considerations

Ischemic ulcers remain difficult to treat. We describe a patient with bilateral ischemic leg ulcers treated preoperatively with pentoxifylline. She had a successful skin graft with no rejection of the graft. The theoretical advantage of treatment with pentoxifylline is discussed, with emphasis not only on its hemorheological properties, but also on its actions on the prostaglandin pathway, platelet aggregation, and thrombosis. We suggest that preoperative pentoxifylline treatment may be a useful adjunct in the closure of ischemic ulcers.     

Infectious laryngotracheitis virus growth,DNA replication,and protein synthesis

Summary The polypeptides associated with infection of primary chicken kidney (CK) cells with infectious laryngotracheitis virus (ILTV) were examined by metabolic labelling with [³⁵S]methionine and SDS-PAGE. Polypeptide synthesis was followed over the first 24 h post-infection (p.i.) as this was shown to be the period of viable virus production. A total of 16 ILTV encoded or induced polypeptides were identified using metabolic labelling. The use of inhibitors of protein and DNA synthesis in conjunction with metabolic labelling and viral DNA replication studies enabled a cascade pattern of gene expression, similar to that of herpes simplex virus type 1 (HSV-1), to be established for ILTV. Representatives of alpha, beta, gamma 1 and gamma 2 classes of genes were identified. In contrast to infection with HSV types 1 and 2, which leads to a rapid inhibition of total host cell polypeptide synthesis, ILTV infection of CK cells did not result in a complete inhibition of cellular protein synthesis, with only a small number of host cell polypeptides absent from infected cells.