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Biomedical subjects

B Ross

Publications and source records attributed to B Ross.

At least 145 records · Page 8Linked to original sources
PubMed1987

Age predicts effective epidural morphine dose after abdominal hysterectomy.

To determine whether there is a relation between patient age and the effective dose of epidural morphine for relief of incisional pain after abdominal hysterectomy, experience treating 66 patients between the ages of 22 and 84 years was retrospectively examined. Linear regressions were plotted for age vs effective 24-hr morphine dose, age vs pain at rest, and age vs pain during coughing. To evaluate the frequency of side effects, the population was classified into three age groups (less than 40, 40-60, greater than 60 yr) and examined by Fisher's exact test for possible differences. Although there was wide interpatient variability, there was a correlation between patient age and effective 24-hr morphine dose (r = -0.40, P less than 0.01). The relation is described by the following equation: 24-hr morphine dose (mg) = 18-age(0.15). The quality of analgesia did not diminish with the smaller doses administered to the older patients. The frequency of side effects did not differ significantly in the three age groups. These observations may be related to higher CSF morphine concentrations or to a greater analgesic effect from morphine absorbed systemically from the epidural space in older patients.

Adult↗
PubMed1986

Contributions of nuclear magnetic resonance to renal biochemistry.

31P NMR as a descriptive technique is of interest to nephrologists. Particular contributions of 31P NMR to our understanding of renal function may be enumerated.: "Free" metabolite levels are different from those classically accepted; in particular, ADP and Pi are low with implications for the control of renal metabolism and Pi transport, and, via the phosphorylation potential, for Na+ transport. Renal pH is heterogeneous; between cortex, outer medulla, and papilla, and between cell and lumen, a large pH gradient exists. Also, quantitation between cytosol and mitochondrion of the pH gradient is now feasible. In acute renal failure of either ischemic or nonischemic origin, both ATP depletion and acidification of the renal cell result in damage, with increasing evidence for the importance of the latter. Measurements of renal metabolic rate in vivo suggest the existence of a prodromal phase of acute renal failure, which could lead to its detection at an earlier and possibly reversible stage. Human renal cancers show a unique 31P NMR spectrum and a very acidic environment. Cancer chemotherapy may alter this and detection of such changes with NMR offers a method of therapeutic monitoring with significance beyond nephrology. Renal cortex and medulla have a different T1 relaxation time, possibly due to differences in lipid composition. It seems that NMR spectroscopy has much to offer to the future understanding of the relationship between renal biochemistry and function.

Acute Kidney Injury↗
PubMed1986

Fistula and sinus formation in xanthogranulomatous pyelonephritis. A clinicopathological review and report of four cases.

Fistula or deep sinus formation as a complication of xanthogranulomatous pyelonephritis (XPN) has not been described previously in the British literature. We present the clinicopathological features of one case of a nephrodiaphragmatic sinus complicating XPN, and three cases of nephrocolic fistula, including the first recorded case of fistula in childhood XPN. The detailed clinical, radiological and pathological features of XPN and its complications are reviewed. Total nephrectomy, together with primary excision of sinuses or fistulae, is the treatment of choice.

Adult↗
PubMed1984

Diagnosis of deep-vein thrombosis: comparison of clinical evaluation, ultrasound, plethysmography, and venoscan with X-ray venogram.

In 50 patients with suspected deep-vein thrombosis the diagnostic accuracy of standardised clinical examination, doppler ultrasound, impedance plethysmography, and technetium-99m-labelled-fibrinogen scintigraphy (venoscan) was compared with that of X-ray venography. Physical examination was the least accurate method. Impedance plethysmography, venoscan, and ultrasound had accuracies of 65%, 80%, and 82%, respectively. The initial X-ray venogram report had an accuracy of 90% compared with the interpretation of two experienced radiologists. The venoscan was equivocal in 32% of patients, and in the remaining patients the accuracy was 97%. Objective methods of investigation are essential for diagnosing deep-vein thrombosis. Of those tested, the X-ray venogram was the only investigation suitable for definitive diagnosis. The venoscan may have a role as a screening procedure, to be followed by X-ray venography in patients with equivocal venoscan results.

Adolescent↗
PubMed1984

Monitoring response to chemotherapy of intact human tumours by 31P nuclear magnetic resonance.

10 kidneys bearing adenocarcinoma (hypernephroma), 1 ureteric tumour, 2 Wilms' tumour from patients undergoing nephrectomy, and normal human and animal kidneys were preserved and later tested to see whether normothermic blood perfusion restored glomerular filtration, oxygen consumption, and energy metabolism, as monitored by 31P nuclear magnetic resonance (NMR). NMR spectra of normal human kidney and of renal tumours were characteristic of kidney in other species (rat, rabbit, and dog), with six principal resonances assigned to adenosine monophosphate, inorganic phosphate (Pi), glycerophosphoryl choline, gamma, alpha, and beta adenosine triphosphate and an intrarenal pH 7.0-7.2. 7 out of 9 hypernephromas and 1 of the 2 Wilms' tumours produced an additional resonance at +4.2 ppm. This peak was absent from all normal kidney spectra and may represent Pi in a specific and highly acidic environment (pH 6.1-6.5) found in actively metabolising human tumours. Furthermore, in 1 tumour (out of 5 tested) the +4.2 ppm peak rose rapidly after the addition of chemotherapeutic agents to the perfusing blood. This observation may indicate drug sensitivity of this one tumour. The results suggest that 31P NMR imaging may be used to monitor therapeutic response during regional perfusion of malignant tumours in man.

Animals↗
PubMed1984

Weighted averaging--theory and application to electric response audiometry.

A weighted averaging technique has been developed to overcome the shortcomings of conventional, unweighted averaging in the case of nonstationary noise. The technique is based on the linear least-mean-square estimate of a periodic signal in a simple model of non-stationary noise. This estimate weights each recorded epoch according to the magnitude of the noise within the epoch. In the estimation of a known signal, the weighted averaging procedure yielded smaller root-mean-square errors in comparison with the normal unweighted average. The weighted averaging procedure offers many advantages over conventional averaging or averaging with automatic gain control preamplifiers.

Audiometry↗
PubMed1984

Psychophysical determination of coordinate representation of human arm orientation.

The coordinate representation of the sense of limb orientation was investigated psychophysically by asking subjects to match the orientation of the arm or of the forearm in several different coordinate representations. Movement of all degrees of freedom of one arm was permitted while movement of the other limb was restricted to the degree of freedom investigated in that particular experiment. Performance on the tasks was assessed by calculating the standard deviation of the difference in the angles of the two limbs. According to this criterion, we suggest that limb orientation is represented by the angular elevation of the limb and by the yaw angle, referred to a spatial reference frame.

Arm↗
PubMed1984

Cholecystoduodenocolic fistula and gallstone ileus.

A patient with cholecystoduodenocolic fistula and gallstone ileus is described. Barium enema and barium meal and follow through demonstrated the passage of the gallstone from the gallbladder region to the small bowel. The clinical features and operative management are discussed in the light of four previously recorded cases.

Aged↗
PubMed1984

Coughs cause systemic blood flow.

Although it is known that rhythmic coughing can preserve consciousness during ventricular fibrillation, the arterial pressure transients which result have not yet been shown to reflect forward blood flow in man. The effectiveness of cough in causing forward flow in eight normal volunteers with bradycardia was studied. They coughed between cardiac cycles, using an audio and visual display of the electrocardiogram. The force of the cough was varied and measured with an oesophageal balloon. Blood flow was recorded with a Döppler velocity probe over the radial artery and a finger or ear photoplethysmograph. Motion artefact on the Döppler record due to coughing was excluded by transiently obstructing the brachial artery. We compared the areas under 5-10 consecutive Döppler and photoplethysmograph pulse flow tracings due to the cough and heart beat with those due to the immediately preceding heart beat alone. They were significantly increased. This augmentation was greater in those flow pulses accompanied by a more vigorous cough. It is concluded that coughing is associated with an effort dependent forward flow pulse in the arterial circulation.

Adult↗
PubMed1983

Energetics of sodium transport in the kidney. Saturation transfer 31P-NMR.

31P-NMR has been used to quantify inorganic phosphate (Pi) and high-energy phosphates in the isolated, functioning perfused rat kidney, while monitoring oxygen consumption, glomerular filtration rate and sodium reabsorption. Compared with enzymatic analysis, 100% of ATP, but only 25% of ADP and 27% of Pi are visible to NMR. This is indicative that a large proportion of both ADP and Pi are bound in the intact kidney. NMR is measuring free, and therefore probably cytosolic concentrations of these metabolites. ATP synthesis rate, measured by saturation transfer NMR shows the P:O ratio of 2.45 for the intact kidney. This is close to the theoretical value, suggesting the NMR visible pool is that which is involved in oxidative phosphorylation. The energy cost of Na transport, calculated from the theoretical Na:ATP of 3.0 exceeded the measured rate of ATP synthesis. Instead, Na:ATP for active transport in the perfused kidney was 12. Since the phosphorylation potential ( [ATP]/[ADP]X[Pi] ) by NMR was 10 000 M-1, the free-energy of ATP hydrolysis was 52 kJ/mol. Using this figure, the rate of ATP hydrolysis observed could fully account for the observed rate of sodium reabsorption.

Adenine Nucleotides↗
PubMed1983

Should surgeons operate on the evidence of ultrasound alone in jaundiced patients?

The biliary ultrasound scans of 132 patients having a laparotomy for jaundice have been reviewed to assess the role of ultrasound in the selection of patients for surgery. When scans were technically satisfactory the finding of a dilated extrahepatic duct (EHD) indicated obstructive jaundice in all cases, but the obstructing lesion in 5 per cent of such cases was too proximal for jaundice to be relieved by direct surgical decompression. Scans were further classified on the basis of abnormalities detected in the gallbladder. When EHD dilation was associated with gall bladder findings 'typical' of distal common bile duct (CBD) obstruction due to gall stones (small gallbladder with multiple gallstones) or tumour (dilated gallbladder without gallstones), surgically remediable obstruction was always present. Although ultrasound identified the obstructing lesion itself in a minority of cases, the cause of obstruction could be correctly inferred in 95 per cent of 'typical' scans. These results suggest that it is safe to proceed directly to surgery only when an experienced ultrasonographer demonstrates findings 'typical' of distal CBD obstruction due to gallstones or tumour.

Bile Ducts↗