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Biomedical subjects

I Gordon

Publications and source records attributed to I Gordon.

At least 127 records · Page 7Linked to original sources
PubMed1994

Effect of recovery method on yield of bovine oocytes per ovary and their developmental competence after maturation, fertilization and culture in vitro.

An important aim of an oocyte recovery method is to maximize the number of oocytes per ovary which can be employed for in vitro maturation (IVM), in vitro fertilization (IVF) and in vitro culture (IVC). In this study, primary bovine oocytes were collected by 2 methods: aspiration of visible follicles (2 to 6mm in diameter) or surface dissection in which the ovary surface is finely dissected. The oocytes were classified on the basis of cumulus cover and cytoplasmic appearance. The total number of oocytes and the yield of good-quality oocytes recovered per ovary by surface dissection and aspiration were 44.2 and 13.9 and 13.5 and 4.6 (P<0.05), respectively. When a sample group of selected oocytes recovered by each method was measured, no significant difference was found in the mean diameter (144.11m vs 142.54m). A representative sample of good-quality oocytes recovered by each method was put through the IVM/IVF/IVC procedure: no significant difference in cleavage rate, cleavage index or blastocyst yield was found. However, when the blastocyst yield was compared on a per ovary basis, a significant difference was observed in favor of surface dissection (3.30+/-0.46 vs 0.96+/-0.16;P<0.05). When unselected oocytes recovered by surface dissection of the ovaries were put through the standard embryo production system, an average of 15.4 blastocysts per dam was obtained.

Journal Article↗
PubMed1994

Improving the accuracy of 99Tcm-mercaptoacetyltriglycine clearance by using two blood samples instead of one? Paediatric Task Group of the EANM.

From a database of 133 patients (98 children and 35 adults) who underwent multiple blood sampling for 99Tcm-mercaptoacetyltriglycine (MAG3) clearance, we determined simplified algorithms allowing the estimation of clearance. A one-compartment model with two blood samples was applied. The best choices for the adult population were the 12 and 90 min blood samples, giving a standard error of the estimate (S.E.E.) of less than 10 ml min-1 1.73 m-2; for the children, the 10 and 80 min blood samples gave a S.E.E. of 20 ml min-1 1.73 m-2; for both the adults and the children, the 10 and 70 min blood samples gave the best results with, however, a S.E.E. of 19 ml min-1 1.73 m-2. The use of such a combined algorithm will therefore result in a degradation of the results in adults, suggesting that a separate algorithm for each group is preferable. We compared the accuracy of the two blood sample method to the one blood sample method based on previously published algorithms for children and adults, respectively. The S.E.E. was significantly lower, in adults as well as in children, using the empirical two blood sample method. This two blood sample method seems potentially useful for routine practice in adult patients. The advantages of using such a method in children is balanced by the practical problems inherent in the need to take a second blood sample during the first 10 min, at a time when the plasma activity is rapidly decreasing.

Adult↗
PubMed1994

Mercapto-acetyltriglycine (MAG 3) renography and indirect radionuclide cystography in posterior urethral valves.

OBJECTIVE: To assess dynamic isotope renography with 99mTc-labelled mercapto-acetyltriglycine (MAG 3) in conjunction with indirect radionucleide cystography (IRC) in the follow-up of boys with posterior urethral valves. PATIENTS AND METHODS: Fifty-one boys (95 renal units; mean age = 89 months, range 65-118) with previously treated posterior urethral vales underwent MAG 3 renography followed by IRC. Glomerular filtration rate (GFR) was estimated from the plasma clearance of 51Cr-ethylenediamine tetra-acetic acid following single intravenous injection. Renographic parameters noted were renal function based on the quality of renal visualization and background activity as well as renal drainage and the appearance of isotope in ureter and bladder. Following the dynamic 20 min MAG 3 renogram the child was allowed to leave the department and to return when he wished to void. IRC was then performed. Diuretics were not administered. RESULTS: Initial drainage from 30 kidneys was normal, in 36 drainage was delayed and in 25 drainage did not occur during the renogram phase. In four kidneys function was so poor as to preclude assessment. After the IRC, drainage was noted in 17 of 25 units which had not drained during the renogram, six units did not drain and in two drainage was equivocal due to the presence of vesico-ureteric reflux. The quality of the scan was good or very good in 42 patients (mean GFR = 92 ml/min/1.73 m2 SA) and moderate or poor in nine patients (median GFR = 20 ml/min/1.73 m2 SA) (P < 0.001). A residual urine was noted following micturition in 35 boys; this was due to incomplete bladder emptying in 14 and to immediate secondary refilling from dilated upper tracts in the remainder. CONCLUSION: IRC in conjunction with traditional dynamic renography using MAG 3 provides valuable additional information about upper tract drainage. The necessity for diuresis renography is obviated in the majority of patients. IRC also allows an excellent non-invasive, physiological assessment of both upper and lower urinary tract function which is superior to conventional single examination techniques. We recommend the use of MAG 3 with IRC in the routine follow-up of boys with posterior urethral valves.

Child↗
PubMed1994

Functional magnetic resonance imaging of focal seizures.

Magnetic resonance imaging (MRI) can now provide maps of human brain function with high spatial and temporal resolution. We aimed to establish whether this noninvasive technique could also map the cortical activation that occurs during focal seizures. In order to do this, we used a conventional 1.5-tesla clinical MRI system for the investigation of a 4-year-old boy suffering from frequent partial motor seizures of his right side. We acquired FLASH images (TE = 60 msec) every 10 seconds over intervals of 10 minutes and derived activation images by subtracting baseline images from images obtained during clinical seizures. Functional MRI revealed sequential activation associated with specific gyri within the left hemisphere with each of five consecutive clinical seizures, and also during a period that was not associated with a detectable clinical seizure. The activated regions included gyri that were structurally abnormal. We concluded that functional MRI can provide new insights into the dynamic events that occur in the epileptic brain and their relationship to brain structure.

Brain↗
PubMed1994

Imaging in systemic hypertension in paediatrics.

The role of imaging is to establish the cause of systemic hypertension, the main focus being the kidneys. All children require a Doppler ultrasound examination followed by a radioisotope study, usually 99mTc-DMSA. This combination will resolve most clinical situations. There is no role for the intravenous urogram in the majority of children. Arteriography and renal vein renin sampling are reserved for a small proportion of children. Imaging should always start with the least invasive procedure with the lowest radiation burden and high radiation techniques reserved for selected cases. The use of ACE inhibition may allow the diagnosis of renovascular disease in paediatrics noninvasively.

Angiography↗
PubMed1994

Normalization of glomerular filtration rate in children: body surface area, body weight or extracellular fluid volume?

UNLABELLED: Glomerular filtration rate (GFR) is usually expressed in relation to body surface area (BSA) for standardization and comparison between individuals of different sizes, although relating it to extracellular fluid volume (ECV) is technically much simpler because the ratio GFR/ECV is almost equal to the rate constant of the second exponential of the 51Cr-EDTA plasma clearance curve. The aim of this study was to investigate the physiological validity of expressing GFR in relation to ECV by comparing it with GFR normalized for BSA and body weight. METHODS: GFR was measured from a five-sample 51Cr-EDTA plasma clearance curve. After appropriate scaling, the rate constant of the terminal exponential is equal to GFR/ECV. RESULTS: GFR normalized by any of the three variables increased between 0-6 mo, but was less in the case of GFR/weight compared with the other two. From 6 to 24 mo, GFR/BSA continued to increase, whereas GFR/ECV and, in particular, GFR/weight remained relatively constant. It appears that as the child grows to age 6 mo, weight outstrips BSA and ECV but is followed by GFR. From 6 to 24 mo, weight, ECV and GFR increase at a faster rate than BSA. By applying regression analysis to the curves of GFR and its normalization variables versus age, expected (e) and relative (r, i.e., observed/expected) values were obtained for each patient. In the age group 6-24 mo, but not 0-6 mo, r[GFR/ECV] was significantly closer to e[GFR/ECV] than the corresponding comparisons with r and e[GFR/BSA] (p < 0.001) and r and e[GFR/weight] (p < 0.002), supporting the hypothesis that as ECV deviates from the expected value for the patient's age, it tends to be followed by GFR. CONCLUSION: Our data show that ECV is the optimal normalization variable in children, particularly those over the age of 6 mo.

Aging↗
PubMed1993

Determination of the technetium-99m mercaptoacetyltriglycine plasma clearance in children by means of a single blood sample: a multicentre study. The Paediatric Task Group of the EANM.

A multicentre European study was undertaken in order to determine a reasonable algorithm allowing the determination of overall technetium-99m mercaptoacetyltriglycine clearance using a single blood sample. Employing multiple blood sample clearance as a reference method, it was shown that an acceptable estimation of the MAG3 renal clearance could be obtained using a blood sample taken at any time between 30 and 40 min after tracer injection. After correction for body surface area, comparison of clearance determined using (a) the single blood sample and (b) the multiple blood samples provided a coefficient of correlation of 0.949 and an SEE of 27 ml/min. This algorithm is valid for clearance values higher than 100 ml/min/1.73 m2 and for children older than 1 year of age.

Algorithms↗
PubMed1993

Hypertension in paediatrics: can pre- and post-captopril technetium-99m dimercaptosuccinic acid renal scans exclude renovascular disease?

In children over 1 year of age, renal disease is the commonest cause of hypertension. Arteriography is considered the reference method to establish the diagnosis of renovascular disease; however, it is an invasive technique with a high radiation burden for children. This was a retrospective study of pre- and post-capto-technetium-99m dimercaptosuccinic acid (DMSA) imaging compared with arteriography in 18 children between the ages of 3 and 17 years. Alone, the 99mTc-DMSA scan is a sensitive indicator of renal parenchymal disease, although non-specific in suggesting the pathology. The combination of pre- and post-captopril studies may increase the sensitivity and specificity in the diagnosis of renovascular disease in the presence of hypertension. This work suggests that a screening investigation with a low radiation burden can be carried out at most institutions; if the investigation is positive, there will be a high index of suspicion that renovascular disease is the cause of the hypertension.

Adolescent↗
PubMed1993

Can renal blood flow, glomerular filtration rate or 99mTc-DMSA uptake predict outcome in experimental unilateral renal obstruction?

Single kidney glomerular filtration rate (SK GFR), single kidney blood flow (SK BF) and differential renal function (DRF), using both technetium labelled diethylene-pentaacetic acid (99mTc-DTPA) and dimercaptosuccinic acid (99mTc-DMSA), were examined as predictors of outcome in a pig model of complete unilateral ureteric obstruction. SK GFR and SK BF were unable to predict outcome following relief of obstruction but there was a high curvilinear correlation between DRF assessed at the end of defined periods of obstruction and after relief of obstruction using 99mTc-DMSA. Functional recovery was near complete using DMSA when the loss in DRF did not exceed 30%, after which there was an exponential decline in expected recovery. There was no difference between DRF using 99mTc-DTPA or 99mTc-DMSA in controls or before or after obstruction but significant differences between assessment by these radionuclides existed in the obstructed kidney at 24 h, 5 days, 10 days and 20 days. 99mTc-DMSA is a sensitive agent in the prediction of outcome following acute complete obstruction in the pig but its assessment of DRF in the obstructed kidney differs markedly from that of 99mTc-DTPA.

Animals↗
PubMed1993

Late pulmonary scintigraphic defects after uneventful recovery from simple focal pneumonia of childhood.

We present a pilot study designed to determine whether pneumonia in children accompanied by focal consolidation on the chest radiograph (CXR) is associated with late abnormality as detected by radionuclide lung scintigraphy. 14 children with focal pneumonia were assessed 1 year after initial presentation. In 12 both krypton-81m ventilation and technetium-99m MAA perfusion studies were performed, while in two only perfusion studies were obtained. All cases had a further CXR. Abnormal or equivocal cases were reviewed clinically. Scans and CXRs were independently assessed by two observers and subsequently consensus reached by discussion. There were five abnormal and nine normal lung scans. Two defects matched the site of the initial pneumonia while three did not. A CXR at the time of lung scanning was normal except for one case with a small focus of consolidation on the opposite side to the initial pneumonia but with a normal lung scan. Similarly, clinical assessment at the time of scanning was unremarkable, with no history of further respiratory episodes except in one child excluded from the study because of an interval diagnosis of asthma. This pilot study indicates that lung scan defects are common in the medium term after supposedly uncomplicated pneumonia in childhood. The cause of these defects remains uncertain. The correlation with the site of the initial radiological abnormality is variable, pointing to the need for further research in this area. The importance of independent blind interpretation is also highlighted.

Child↗
PubMed1993

Obliterative bronchiolitis with atypical features: CT scan and necropsy findings.

We describe the natural history of cryptogenic bronchiolitis obliterans in a patient followed for 24 yrs with serial pulmonary function tests and radiology. Severe, progressive airway obstruction developed, with overinflation but preservation of KCO. There was progressive hypoxaemia, which worsened on exertion; hypercapnoea was modest until late in the illness. Neither bronchodilators nor steroids were effective. The chest radiograph remained normal; CT showed irregular areas of low attenuation peripherally throughout the lungs, with Hounsfield numbers typical of emphysema, but no bullae. Postmortem studies included histology and quantitative studies of a corrosion cast of one lung. They showed marked airway narrowing at all levels, with pruning of peripheral branches, mucus plugging, and some emphysema. The case illustrates that cryptogenic bronchiolitis obliterans may be chronic and difficult to distinguish clinically or by investigation from other forms of chronic obstructive airways disease, particularly emphysema.

Adult↗
PubMed1992

Effect of posture on regional ventilation in children.

Little information has been published concerning the pattern of regional ventilation in children, yet many differences in lung and chest wall mechanics in childhood, supported by clinical observation, have led to the hypothesis that the pattern of regional ventilation seen in children may not be the same as in adults. Forty-three children and 16 adult volunteers underwent Krypton (Kr) 81m radionuclide ventilation lung scans in the supine and right and left decubitus postures. In children aged 2-10 years mean fractional ventilation to the right lung (VfR) was 46.1%. This fell to 36% when dependent and rose to 56.1% in the uppermost position. Redistribution of ventilation away from the dependent towards the uppermost lung was seen in all children. In children aged 10-18 years VfR was 57.2% (supine), 48.0% (dependent), and 62.9% (uppermost). An identical pattern was seen in children with normal or abnormal pulmonary function tests (peak expiratory flow rate, and FEV1: FVC ratio). In subjects over 18 years of age a different pattern was seen: mean VfR was 52.4% (supine), rising to 53.4% (dependent), and falling to 48.9% (uppermost). Postural redistribution of ventilation, as assessed by Kr81m ventilation imaging, changes late in the second decade of life. This will have clinical consequences in the management of children with unilateral lung disease.

Adolescent↗
PubMed1992

Urinary endothelin (ET1) in complete ureteric obstruction in the miniature pig.

Segmental renal scarring occurs in experimental obstructive uropathy in the multipapillary porcine kidney, and segmental abnormalities in renal perfusion are likely to be responsible. This preliminary study examines the urinary excretion of the potent locally active vasoconstrictor endothelin 1 (ET 1) in a pig model of renal obstruction and subsequent relief. Significant urinary excretion of ET 1 from the postobstructive kidney was found to occur after longstanding obstruction. Preglomerular arteriolar stenosis may be the cause of the renal ischaemia in obstruction that is at first reversible but later becomes irreversible if the stimulus persists. ET 1 may be implicated in the pathogenesis of this injury.

Animals↗
PubMed1992

Vesico-ureteric reflux in the damaged non-scarred kidney.

Renal damage without scarring is a rare manifestation of reflux nephropathy, and is infrequently reported in the literature. A retrospective review of a large series of patients with urinary tract disorders at the hospital for Sick Children, Great Ormond Street, identified 12 patients with vesico-ureteric reflux (VUR) with no evidence of scarring but with renal damage as assessed using technetium 99m dimercaptosuccinic acid (99mTc-DMSA) scan. There were 9 simplex kidneys, the differential function was between 33% and 43% (mean 38%). On follow-up to date (mean 6.7 years) all kidneys show stable differential function with neither improvement nor deterioration. Only 8 children had a urinary tract infection. Renal damage without evidence of a focal scar associated with VUR may be a manifestation of growth arrest possibly due to glomerular damage. The sensitivity of 99mTc-DMSA may reveal the permanent nature of the renal damage.

Child↗