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K Evans

Publications and source records attributed to K Evans.

At least 127 records · Page 7Linked to original sources
PubMed1991

Estimation of technetium-99m-MAG3 renal clearance in children: two gamma camera techniques compared with multiple plasma samples.

Dynamic renal scintigraphy using technetium-99m mercaptoacetylglycylglycylglycine (MAG3) has been described in adults, and clearance values have been established using multiple plasma samples. This study of renal clearance has compared two fundamentally different gamma camera techniques (both of which require a single blood sample) with the multiple blood sampling technique in children (n = 30). Results show that a 40-min dynamic 99mTc-MAG3 renal scintigram coupled with a single plasma sample will allow analysis of the data so that clearance values, which are similar to those from multiple plasma samples, may be calculated. The curve generated from the cardiac region of interest (ROI) provided clearances values that had a high correlation coefficient (0.939-0.951) compared to the multiple-plasma sample technique immaterial of the timing of the blood sample. The renal uptake method of clearance had a lower correlation coefficient (0.89-0.92), which varied with the timing of the blood sample compared to the multiple-plasma sampling technique. This study has demonstrated that an extended gamma camera acquisition coupled with a single-plasma sample may be used for quantitative renal function studies using 99mTc-MAG3.

Adolescent↗
PubMed1990

Quantitation of vesico-ureteral reflux by radionuclide cystography and urodynamics.

A method is described for the quantitation of vesico-ureteral reflux by synchronous combined direct radionuclide cystography and urodynamics. Intravesical pressures and volumes are co-ordinated with volumes of reflux. Peak reflux volumes in 11 children diagnosed as having severe (grades 3-4) reflux on conventional contrast cystography ranged from 1 to 50 ml/kidney. A number of different patterns of reflux were observed. Reflux may occur progressively throughout low pressure filling or incrementally with unstable bladder contractions. Reflux during voiding may be maximal as detrusor pressure falls. The method requires wider application to explore the potential for a functional classification of the reflux problem.

Child↗
PubMed1990

Physical determinants of the endocardial P wave.

UNLABELLED: Reliable atrial sensing of intrinsic P wave activity is important to ensure optimal atrial or dual chamber pacemaker function. Various physical factors (e.g., posture, respiration, exercise) may influence P wave characteristics and impair adequate sensing. To investigate this phenomenon, we measured the average of three P wave amplitudes (PWA) and calculated slew rates from telemetered printouts acquired from Pacesetter pacemakers in 32 patients. These measurements were performed in various body positions, with upright exercise and in varying stages of respiration. RESULTS: the mean supine PWA increased on full inspiration (3.56 +/- 1.3 mV versus 3.25 +/- 1.2 mV during quiet respiration, P less than 0.001), and also increased significantly with full expiration. The mean PWA increased on assuming the erect position (3.25 +/- 1.2 mV increasing to 3.49 +/- 1.3 mV, P less than 0.001); in the upright position, the mean erect PWA during quiet respiration was not significantly influenced by the stage of respiration. The mean upright exercise PWA did not differ significantly from the preexercise erect PWA (3.50 +/- 1.2 with exercise, and 3.47 +/- 1.5 before exercise; P = NS). Calculated slew rates were not different lying versus standing. CONCLUSIONS: the mean supine PWA increases significantly at the extremes of respiration and on assuming the erect body position; upright exercise results in no appreciable change in the erect PWA. Atrial sensitivity adjustments based on standard supine testing should be adequate for all body positions.

Adolescent↗
PubMed1990

True incidence of pacemaker syndrome.

Although the purported incidence of pacemaker syndrome according to the literature is only 5%-15%, this is based on a series of patients with VVI pacing. Increasing numbers of studies are being reported in which patients prefer the dual chamber mode despite little benefit being demonstrated on objective testing, suggesting that pacemaker syndrome may be more common than is generally reported. This study was designed to evaluate the reported symptoms in a series of patients programmed to both the VVI and one or more dual chamber modes. Forty unselected patients with dual chamber pacemakers were entered into a blind, randomized trial comparing the symptoms associated with VVI pacing to those associated with dual chamber pacing. Patients were randomized to either VVI or dual chamber pacing. At the end of 1 week, questionnaires rating 16 different symptoms were completed. Blood pressure, LV function, presence of ventriculoatrial conduction, and ability to override the pacemaker were evaluated. The pacemaker was then programmed to the other mode. Overall, 12 of 16 symptoms were significantly worse in the VVI as compared to dual chamber mode. The most highly significant (P less than 0.005) were shortness of breath, dizziness, fatigue, pulsations in the neck or abdomen, cough, and apprehension. Pacemaker syndrome was clinically recognized in 83% of patients paced in the VVI mode with 65% of patients experiencing moderate to severe symptoms. There were no readily identified clinical, hemodynamic, or electrophysiological parameters that predicted which patients would develop pacemaker syndrome. Thus, when patients have an opportunity to experience both pacing modes in close proximity to one another, there is a high incidence of pacemaker syndrome in the VVI mode.

Aged↗
PubMed1989

The accumulation of organotins in adult and seed oysters from selected estuaries prior to the introduction of U.K. regulations governing the use of tributyltin-based antifouling paints.

Between April and November, 1985, a study of the levels of organotins in adult and seed Crassostrea gigas grown in the southwest and southeast of England was carried out. This work corresponds with a similar study of organotin water levels (reported separately). The analytical procedure used was directly coupled high performance liquid chromatography-flame atomic absorption spectrometry. Individual adult oysters and groups of 20-40 seed oysters were taken for analysis on a monthly basis. The profiles of tributyltin (TBT), dibutyltin (DBT) and monobutyltin (MBT) are discussed in relation to each other and levels found in the waters. In general, levels of all three organotin species were found to be higher in the seed oysters. Mean levels of TBT reached 3.1 micrograms g-1 in seed oysters from the Exe, Devon, in October, whereas mean levels of DBT and MBT reached 16.1 and 16.7 micrograms g-1 in Teign, Devon, seed oysters in October. Bioconcentration factors of approximately 1000 were found, but seem to be greater when lower levels of TBT were present in the water, perhaps indicating a more 'efficient' removal from the water. The degree of shell thickening was calculated for all oysters submitted for analysis. The highest percentage of adult oysters with severely thickened shells was found at Tollesbury Fleet, where 61% of oysters showed shell thickness index values of six or less. Generally, two peaks in TBT levels in the oysters were observed, in the late spring and early summer: these seem to correlate with peak levels of TBT in the waters immediately preceding these times. A large proportion of the DBT and MBT found in the oysters seems to come from the metabolism of the TBT ingested. It is suggested that high sediment loadings may contribute to the severe deformation of oysters grown at Tollesbury Fleet, but only in the presence of TBT.

Aging↗
PubMed1989

Impact of new radiotherapy modalities on the surgical management of cancer of the esophagus and cardia.

At the Cancer Control Agency of British Columbia, 483 patients with cancer of the esophagus and cardia were seen from 1970-1980. Four hundred and one out of 483 (83%) had tumors larger than 5 cm (T2) and in 288/483 (60%) the disease had extended beyond the esophageal wall (T3). The overall 5-year survival rate was only 9% for all patients treated by external irradiation. The 5-year survival for a selected group having esophagectomy was 20%. Most patients died of persistent cancer at the primary site (83%); the cause of death was aspiration pneumonia (82%) due to obstruction caused by the persistent cancer. Our most recent experience using intracavitary irradiation either prior to or after external irradiation in 211 patients has been safe and simple and preliminary analysis of treatment results suggests that it has improved the therapeutic ratio. The analysis of quality of life at 6 months following therapy as it relates to performance status, swallowing ability, weight, and pain indicated significant improvement in all of these parameters. Of 171 patients, 33% were still alive at 1 year, 26% at 2 years, and 19% at 3 years following treatment. Of 43 patients suitable for preoperative irradiation, only 26 patients were actually resected and 19 of them are still alive with no evidence of disease, 8 to 30 months. The rationale and technical aspects of the combined treatment are described in detail. Treatment results, complications and an outline for future programs based on this experience are also described.

Body Weight↗
PubMed1988

Two routes for 99mTc-DMSA uptake into the renal cortical tubular cell.

Critical factors determining the renal handling of 99mTc-dimercaptosuccinic acid (DMSA) are protein binding in plasma and the renal 99mTc-DMSA extraction efficiency. Comparison of the count rate over soft tissue with that over the cardiac blood pool about 1 h after injection demonstrated that 99mTc-DMSA is not exclusively an intravascular label. 99mTc-DMSA was 76% protein bound in plasma as demonstrated by HPLC and gel filtration. Assuming that the 24% that is not protein bound is filtered at the glomerulus, the renal extraction efficiency of 99mTc-DMSA by glomerular filtration is about 5%. Since the total renal extraction efficiency was also found to be about 5%, the majority of the activity that becomes fixed in the renal cortex arrives there as a result of filtration followed by tubular reabsorption rather than by direct extraction from peritubular blood. However, discordant changes in DMSA and DTPA uptake induced by captopril in renovascular hypertension (RVH) suggested that a minority of uptake was by direct peritubular extraction. This kinetic model was supported by indirect measurement of protein binding and extraction efficiency based on the kinetics of 99mTc-DMSA disappearance from plasma and kinetics of uptake in the kidneys. Furthermore, differential functional studies based on 99mTc-DMSA and 99mTc-DTPA before and after captopril in patients with RVH due to unilateral renal artery stenosis confirmed filtration followed by tubular reabsorption as the predominant route for DMSA uptake by the kidney.

Adult↗
PubMed1988

The biodistribution and pharmacokinetics of meta-iodobenzylguanidine in childhood neuroblastoma.

MIBG is generating considerable interest for the treatment of neuroblastoma. This study has investigated the biological variation in handling of the compound in children with neuroblastoma. The biodistribution of the compound has been characterised in children undergoing tracer administrations of 123I and 131I-mIBG. Estimates of hepatic and whole body radiation dose delivery have been made. The results indicate substantial interpatient variation in hepatic dose delivery. This organ may be critical in some patients undergoing targeted radiotherapy with mIBG.

3-Iodobenzylguanidine↗
PubMed1988

Background in 99Tcm DTPA renography evaluated by the impact of its components on individual kidney glomerular filtration rate.

Following injection for renography, 99Tcm-labelled diethylenetriamine-pentacetic acid (DTPA) rapidly enters the extravascular space. Background therefore comprises two components, a falling intravascular signal and an extravascular signal which initially rises. We estimated the relative magnitudes of these two components in terms of their impact on the calculation of differential renal function and individual kidney glomerular filtration rate (IKGFR) from the second phase of the 99Tcm-labelled DTPA renogram in 56 paediatric kidneys. We expressed each of the two background signals as a GFR equivalent. The GFR equivalent of the intravascular signal recorded from a peri-renal background region of interest (ROI), scaled by a factor equal to the ratio of the pixel numbers in the renal and background ROIs, was -39 (S.D. 14) ml min-1. The GFR equivalent of the extravascular signal was smaller than this and opposite to it at 23 (S.D. 10) ml min-1, giving a median ratio for the two equivalents of -1.68. Because of the opposing effects of the two background components on the second phase of the renogram, techniques recently described for the quantification of IKGFR from the renogram, and which eliminate the intravascular component, offer no theoretical advantage over a method of analysis which uses 'direct' subtraction of the total background signal. In practice, however, these new techniques are superior in their handling of 'noisy' data, consistently giving a lower coefficient of variation in their estimation of IKGFR.

Child↗
PubMed1987

Laser treatment of obstructive endobronchial tumors: factors which determine response.

To investigate whether computerized tomography (CT) and radionuclide quantitative ventilation-perfusion lung scan add any useful information to a carefully performed endoscopic examination in determining the response of patients with obstructive endobronchial tumors to laser treatment, the findings in 40 patients treated with photodynamic therapy (PDT) or the Nd:YAG laser were analysed. Endoscopic laser treatment was found to be most effective when the tumor was polypoid in appearance bronchoscopically, with little or no submucosal invasion or peribronchial extension seen on CT. When bronchoscopy and CT showed increasing submucosal and/or peribronchial disease, the immediate and long-term response to treatment was poorer. CT provided valuable information regarding the extent of the peribronchial involvement and airway distortion which were often underestimated by bronchoscopy alone. Reduction of regional perfusion out of proportion to ventilation on scintigraphy in the involved lung zone was found to be associated with extensive peribronchial involvement. We conclude that the addition of CT and radionuclide quantitative ventilation-perfusion lung scan to bronchoscopic examination is useful in predicting the response of patients with obstructive endobronchial tumors to laser treatment. Whether PDT or YAG laser is more effective in relieving endobronchial obstruction by tumor awaits a randomized controlled trial.

Aged↗
PubMed1987

Abnormalities of copper in Gilles de la Tourette syndrome.

The Gilles de la Tourette syndrome is a disorder whose etiology and pathogenesis are little understood. The number of biochemical abnormalities described in this disorder is minimal. Ten of a total of 80 patients were found to have an abnormally low serum copper. A report is presented on two patients who consented to further detailed investigation and in whom copper radioisotope studies were carried out. Both exhibited abnormalities of copper handling, in that we observed an abnormally fast disappearance of copper from the plasma and an abnormally slow uptake by the liver. The rates of intestinal absorption and urinary excretion were normal. We did not identify an abnormal site of sequestration of the metal in the body.

Adult↗
PubMed1987

Background in the 99mTc DTPA renogram: analysis of intravascular and extravascular components.

Individual kidney glomerular filtration rate (IKGFR) was calculated from the upslope of the 99mTc-diethylenetriamine pentaacetic acid (DTPA) renogram in ten children with a normal solitary kidney (on the right in five and on the left in five). By using a method of renogram analysis that is independent of the intravascular (IV) component of background (BG) activity, the IV and extravascular (EV) components of background were separately quantified in various regions in proximity to the nephrectomy site. The size of the IV compartment was expressed as an absolute plasma volume (PV-BG), and that of the EV compartment was expressed as a "GFR equivalent," i.e., the undirectional rate of fluid transfer from the IV to EV spaces in ml per min (GFR-BG). The region areas from which these parameters were calculated were normalised to the area projected by the solitary kidney. In a region centred over the lower pole of the imagined absent kidney, PV-BG was 129 +/- 7 ml (SE) and GFR-BG was 28 +/- 1.8 ml per min. The corresponding values centred over the liver/spleen on the nephrectomised side were 353 +/- 24 ml and -2 +/- 2.9 ml per min, respectively. PV-BG, but not GFR-BG, was significantly higher over the liver (397 ml and -6.8 +/- 1.5 ml per min) compared with the spleen (287 ml, P less than .05; and 4.5 +/- 3.2 ml per min, P greater than .05). PV-BG and GFR-BG in a region placed over the centre of the nephrectomy site were intermediate between those superior and inferior: 231 +/- 17 ml and 15 +/- 2.7 ml per min, respectively. The IV signal rises while the EV falls during the second phase of the renogram. In the analysis of the renogram during this phase, therefore, background should be based on both supra- and subrenal regions of interest.

Child↗
PubMed1987

Uncorrected refractive error among a hospital population.

Patients admitted for general medical care to a North London Hospital were screened using a pinhole disc in conjunction with their usual visual aid. One third of the group showed significant improvement in visual acuity, suggesting a change in refractive correction was necessary. These people were not more likely to have had less recent eye examinations or to complain of poor vision. They were more likely to be over 50 years old, have poor mobility, to have no idea of cost of change in refractive correction and to subjectively note improvement in vision with pinhole disc.

Adolescent↗
PubMed1986

Isolation and sequence of cDNA clones coding for the precursor to the gamma subunit of mouse muscle nicotinic acetylcholine receptor.

cDNA libraries have been constructed in plasmid (pBR322) and bacteriophage lambda gammagt10) vectors with poly (A+) RNA isolated from the nonfusing mouse muscle cell line BC3H-1. The libraries were screened with a restriction fragment derived from a genomic clone coding for a human acetylcholine receptor gamma subunit. Several clones were obtained whose cDNA inserts possessed nucleotide and deduced amino acid sequence homology with acetylcholine receptor gamma subunits from Torpedo californica, chick, calf, and human. One isolate, lambda BMG419, has 88 nucleotides of 5'-untranslated sequence, an open reading frame of 1,557 nucleotides coding for the precursor to the mouse acetylcholine receptor gamma subunit, and 144 nucleotides of 3'-untranslated sequence. Alignment of the lambda BMG419-deduced amino acid sequence with homologs from other species predicts a precursor peptide of 519 amino acids and a mature protein of 497 amino acids, with nonglycosylated molecular weights of 58,744 and 56,424 daltons, respectively. Comparison of the deduced amino acid sequence of the mouse gamma subunit with Torpedo, chick, calf, and human sequences showed overall homologies of 54%, 67%, 90%, and 90%, respectively; however, significantly higher homologies were found in several putative functional domains. Radiolabeled lambda BMG419 has been used to identify homologous RNA species, one of approximately 2 kb and one of about 3.5 kb, in poly (A+) RNA prepared from BC3H-1 cells and denervated mouse limb muscle. gamma Subunit-coding RNA species are considerably more abundant in denervated than in innervated muscle, suggesting that neural regulation of the abundance of the gamma subunit is exerted through regulation of the amount of its mRNA.

Animals↗
PubMed1986

Children's pain vocabulary.

This paper will address children's pain vocabulary, that is, the self-reported words provided by the children, in a descriptive study carried out to examine how a group of school-age children view their pain. This was an initial step to demonstrate that children can describe pain and do possess a pain vocabulary. Our aim was to determine the feasibility of achieving a meaningful grouping of children's pain words and the pain intensity implied by the words. A sample of 40 school-age children were the subjects for this study. All the pain word descriptors used by the children in response to the question 'Can you think of words to describe what pain feels like?' were categorized on the basis of the Melzack classification.

Child↗