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Biomedical subjects

I Gordon

Publications and source records attributed to I Gordon.

At least 37 records · Page 2Linked to original sources
PubMed2001

Diuretic renography in infants with prenatal unilateral hydronephrosis: an explanation for the controversy about poor drainage.

OBJECTIVE: To present an explanation for impaired drainage on diuretic renography in infants with a prenatal diagnosis of unilateral renal pelvic dilatation (RPD) who are stable both in terms of renal function and dilatation on follow-up investigations, despite undergoing no surgical intervention, and who undergo diuretic renography postnatally; this should provide some insight into whether impaired drainage is a sign of obstruction in these asymptomatic infants. MATERIALS AND METHODS: Using a combination of published studies on the technique of diuretic renography and an analysis of such studies, a theoretical model of the infant kidney was developed to assess the possibility of prolonged drainage. RESULTS: The results from the model showed prolonged drainage in many different situations, thus offering an explanation of expected impaired drainage even if there was no obstruction. CONCLUSION: Understanding the pathophysiology of prenatally diagnosed RPD allows different interpretations of the diuretic renogram and may affect the treatment of these children.

Child, Preschool↗
PubMed2001

Preoperative assessment of hand circulation by means of Doppler ultrasonography and the modified Allen test.

OBJECTIVE: The aims of this study were as follows: (1) to evaluate Doppler ultrasonography in assessing hand collateral circulation; (2) to define the criteria for an abnormal Doppler ultrasonography dynamic test result; and (3) to validate the modified Allen test. METHODS: The hand circulation of 71 patients scheduled for coronary artery bypass grafting was assessed by means of the Allen test and Doppler ultrasonography. The flow in the superficial palmar branch of the radial artery, the ulnar artery, and the dorsal digital thumb artery with and without radial artery compression were recorded. Flow patterns in the superficial palmar branch of the radial artery, the ulnar artery, and the dorsal digital thumb artery with radial artery compression were categorized into 4 groups: (1) no flow; (2) decreased flow; (3) reversed flow; and (4) increased flow. RESULTS: Among the 71 hands, 4 (5.6%) had an abnormal Allen test result (>10 seconds). Seven (10.6%) of 66 superficial palmar branches of the radial artery, 3 (4.2%) of 71 ulnar arteries, and 2 (2.8%) of 71 dorsal digital thumb arteries showed no flow with radial artery compression, as measured by Doppler ultrasonography. There were significant differences among the 4 groups (superficial palmar branch of the radial artery: F = 7.0, P <.001; ulnar artery: F = 13.1, P <.001; and dorsal digital thumb artery: F = 8.4, P <.001) for the Allen test. Pairwise comparisons showed that when subjected to an Allen test, category 1 patients (no flow) had significantly longer recovery times compared with the other groups (P <.02 in all cases) for the superficial palmar branch of the radial artery, the ulnar artery, and the dorsal digital thumb artery. CONCLUSION: Absence of flow in the dorsal digital thumb artery with radial artery compression is considered an absolute contraindication to radial artery harvesting. An increased recovery time with the modified Allen test predicts absence of flow in the dorsal digital thumb artery in Doppler ultrasonographic flow patterns. This demonstrates the validity of the modified Allen test for primary screening.

Aged↗
PubMed2001

Neonatal hypothyroid disease: absent salivary gland evident on technetium-99m pertechnetate scan.

PURPOSE: Technetium-99m pertechnetate scintigraphy is a well-established technique for diagnosing congenital hypothyroid disease. However, the biodistribution of pertechnetate (TcO4-) in neonates and young infants is not well documented. The purpose of this study was to analyze and document the biodistribution of TcO4- in young infants. MATERIALS AND METHODS: Scintigraphic studies of 31 patients being examined for hypothyroid disease were analyzed. All patients had elevated levels of thyroid-stimulating hormone. Dyshormonogenesis was diagnosed in 7 patients, ectopic thyroid glands in 19, and agenesis in 5. RESULTS: Images of the neck, chest, and abdomen taken in the anterior and left lateral positions using a low-energy, all-purpose collimator were reviewed. Twenty-six of the patients had no accumulation of the isotope in the salivary glands and 11 had no gastric uptake on either view. CONCLUSIONS: Based on the absence of salivary gland activity in the patients examined, this study suggests that this is a normal finding in infants younger than 3 months. A lateral view of the neck with markers is sufficient to localize the thyroid gland, because any activity in the neck region would belong to the thyroid. Furthermore, poor and variable uptake of the isotope in the stomach may lead to false-negative results, so caution is urged in the use of this tracer in Meckel's scintigraphy in young infants, particularly if the study findings are within normal limits.

Congenital Hypothyroidism↗
PubMed2000

Quantitative analysis of the developing rat kidney: absolute and relative volumes and growth curves.

The development of the permanent kidney, or metanephros, is a complex process. In the present study, stereological methods were used at the light microscopic level to estimate the absolute volumes and volume densities of seven compartments in the developing rat metanephros, from embryonic day 14 (E14) to E21. Metanephroi from time-mated Sprague-Dawley rats were embedded whole in glycolmethacrylate, exhaustively sectioned at 2 microm and stained with PAS. The left metanephros from three embryos from each of three mothers were analysed at each of the ages (a total of 72 metanephroi). Relative volumes were multiplied by total metanephric volume to obtain absolute volumes. Total metanephric volume increased approximately 300-fold during the 7-day period studied. At E14, 92% of the metanephros was composed of undifferentiated mesenchyme, whilst the ureteric epithelium made up approximately 5% of the volume. By E21 the undifferentiated mesenchyme comprised 47% of the kidney, while the ureteric epithelium comprised 9% and the various components of developing nephrons (epithelial vesicles, comma-shaped bodies, S-shaped bodies, glomeruli, tubules) comprised 43%. Equations with prediction intervals describing the growth of the whole kidney as well as the absolute and relative growth of the seven kidney compartments were generated. These data provide a baseline for future studies on the roles of specific molecules in renal development.

Animals↗
PubMed2000

The combination of bcl-2 expression and NGF-deprivation facilitates the selective destruction of BAD protein in living sympathetic neurons.

Bcl-2 overexpression prevents neuronal death after injury or neurotrophic factor-deprivation but the biochemical consequences of survival maintenance by Bcl-2 have hardly been explored. We show that unlike NGF, adenovirally delivered hBcl-2 supports the survival of over 80% of the neurons without activating ERK and Akt phosphorylation, or suppressing JNK phosphorylation, or enhancing cell growth. However, the proapoptotic protein BAD, whose phosphorylation is induced by NGF, is degraded in NGF-deprived neurons expressing hBcl-2, while the level of Bcl-xL remains unaffected. Interestingly, degradation of BAD protein is prevented by the pan-caspase inhibitor Boc.Asp(OMe)fmk. We propose that NGF-deprivation promotes dephosphorylation of BAD while hBcl-2 facilitates its release into the cytoplasm where it is degraded by noncaspase, Boc.Asp(O-Me)fmk-inhibitable proteases. The potential importance of BAD degradation is suggested by our finding that overexpressed BAD kills NGF-maintained sympathetic neurons by apoptosis, while hBcl-2 prevents BAD-induced death.

Adenoviridae↗
PubMed2000

Potential pitfalls in nuclear medicine: a paediatric teaching case.

An infant with complex cardiac defects and isomerism had a persistent pyrexia of undetermined aetiology following cardiac surgery. Radionuclide leucocyte scan showed a focus of increased uptake in the right upper quadrant (RUQ) felt to be compatible with an abscess. However, correlation with clinical data and multimodality imaging allowed the correct diagnosis of ectopic splenic tissue in the RUQ to be made. This report emphasises the need for an integrated approach to imaging. Patients with abnormalities of viscero-atrial situs require careful assessment of their splenic status. Visceral heterotaxy may result in confusing imaging appearances unless the anatomy has been accurately documented.

Abdomen↗
PubMed2000

Time course of severe respiratory syncytial virus infection in mechanically ventilated infants.

The time course of intensive care for severe respiratory syncytial virus (RSV) lower respiratory tract illness may be predicted by the severity of gas exchange during the first 48 h of mechanical ventilation. To test this hypothesis, two studies were undertaken in RSV-positive mechanically ventilated patients who did not have chronic lung disease, congenital heart disease or immunodeficiency. First, a retrospective criteria-generating review of 45 infants was carried out. In these infants, more severe lower airway disease, as demonstrated by four-quadrant consolidation on chest X-ray, was associated with 'best' alveolar arterial oxygen gradients (AaDO2, torr) and mean airway pressure (MAP, cm H2O) values as follows: first 24h, AaDO2 > 400 and MAP > 10 (positive and negative predictive values 100% and 97%, respectively); second 24 h, AaDO2 > or = 300 and MAP > 10 (positive and negative predictive values 91% and 100%, respectively). The second study, a prospective, hypothesis-testing, analysis of length-of-stay in 44 infants stratified according to the above AaDO2 and MAP criteria demonstrated that the duration of intensive care was longer in the severe group: median (interquartile range in days) 17 (15-39) vs 7 (4-8) (p < 0.01). We suggest that, in mechanically ventilated infants with RSV, the time course of intensive care is predictable based on early clinical features and respiratory parameters. Therefore reports on the effectiveness of special therapies using intensive care stay as a measure of outcome should be interpreted with respect to these observations before drawing conclusions about efficacy.

Humans↗