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Biomedical subjects

P L Allan

Publications and source records attributed to P L Allan.

At least 19 recordsLinked to original sources
PubMed1992

Screening patients with claudication from femoropopliteal disease before angioplasty using Doppler colour flow imaging.

Time, expense, risk and discomfort are incurred by arteriography in patients with intermittent claudication who might be candidates for percutaneous transluminal angioplasty (PTA). A valid screening technique could reduce the need for arteriography in patients found to have lesions not amenable to PTA. Agreement between Doppler colour flow imaging (DCFI) and angiography for detecting haemodynamically significant lesions is high, but DCFI may not identify lesions suitable for angioplasty. A total of 36 limbs in 30 patients were studied using DCFI before angiography. Agreement between the two methods was excellent (kappa = 0.91), and the predictive accuracy of DCFI for lesions amenable to PTA was good (kappa = 0.78, sensitivity 94 per cent, specificity 85 per cent, positive predictive value 83 per cent, negative predictive value 94 per cent, overall accuracy 89 per cent). DCFI is a useful screening process that may prevent unnecessary angiography, with consequent financial savings and clinical benefit.

Aged↗
PubMed1992

Ultrasonography of the native kidney in dialysis and transplant patients.

The native kidneys in patients on dialysis or after transplantation tend to be overlooked until problems occur in relation to them. Their appearance can be variable and does not bear any consistent relationship to the cause of the renal failure; although in some cases, such as polycystic kidney disease, there are specific changes to be seen. Size can also be variable with little correlation to pathology in most cases. Acquired cystic disease of the kidneys is seen in up to 92% of long-term dialysis patients and also can be seen in patients with chronic renal failure. Proliferative changes occur in the kidneys which result in the development of cysts, adenomas and, in approximately 1% to 2% of dialysis patients, malignant lesions. It is probable that these changes are caused by a combination of factors, including circulating agents which are not cleared adequately by dialysis. There is some evidence that these changes are halted, or even reversed following a successful transplant. Problems with infection and hemorrhage may occur in patients with polycystic kidney disease. Problems with infection may also occur in patients with calculi, with longstanding pyelonephritis, or reflux.

Humans↗
PubMed1992

Validity of duplex scanning in the detection of peripheral arterial disease in the general population.

Duplex scanning has the potential to identify asymptomatic atherosclerosis of the lower limbs in the general population. The aim of this study was to assess the validity of scanning in a group of men and women aged 55-74, sampled from a population survey. Disease was measured using the WHO questionnaire on claudication, the ankle brachial pressure index, and a reactive hyperaemia test. In 73 cases of peripheral arterial disease and 91 controls, a duplex scan was conducted on both legs from the inguinal ligament to the lower popliteal region. The two radiologists performing the scans were blind to the arterial status of the subjects. Interpretation of the image, waveform and peak systolic velocity resulted in a sensitivity of 78%, specificity of 65% and positive predictive value of only 19%. The image alone had the best positive predictive value (62%) and specificity (97%). These results suggest that duplex scanning may currently be of limited use as a diagnostic screening test in the general population. Interpretation of the image alone, however, may be useful in some settings in identifying healthy subjects free of disease.

Aged↗
PubMed1992

Effects of angiotensin converting enzyme inhibition in adult polycystic kidney disease.

The pathogenesis of hypertension in autosomal-dominant polycystic kidney disease (ADPKD) is unclear, but increased activity of the renin-angiotension system may contribute. The renal and systemic hemodynamic response to lisinopril, an angiotension converting enzyme (ACE) inhibitor, in patients with ADPKD without renal failure was compared with the response in matched unaffected family members. Mean blood pressure and renal vascular resistance decreased in the affected group after lisinopril, with no significant change in the unaffected group. Glomerular filtration rate (GFR) was unchanged and therefore filtration fraction fell significantly. Changes in urinary excretion of 6-keto-PGF1 alpha and kallikrein suggested that increased renal synthesis of PGI2 or activation of the renal kallikrein-kinin system were not likely to be responsible for the hemodynamic effects. The acute decrease in renal vascular resistance without change in GFR suggests that ACE inhibition may have a particular value in the treatment of hypertension associated with ADPKD which should be assessed by further long-term studies.

6-Ketoprostaglandin F1 alpha↗
PubMed1992

Effect of treatment mode on the natural history of acquired cystic disease of the kidney in patients on renal replacement therapy.

The natural history of acquired cystic disease of the kidney has been investigated in a long-term follow-up study of patients on renal replacement therapy. A cohort of 145 end-stage renal failure patients was initially investigated with ultrasonography to determine the degree of cystic change. Seventy-three patients were available for follow up a minimum of 3 years later. The grade of cystic disease progressed in dialysis patients and progression was more marked in haemodialysis patients than patients maintained on CAPD. Patients with functioning renal transplants did not show progression of cystic change and in two patients regression was seen. Nine patients maintained on chronic dialysis at the time of initial ultrasound subsequently received renal grafts, and three of these patients had evidence of regression of cystic change on follow-up scanning. After 3 years follow-up a single haemodialysis patient had evidence of a solid lesion in a cystic kidney and this has not progressed during a further 12 months of follow-up. Acquired cystic disease of the kidney is a progressive disease in chronic dialysis patients. However, over a follow-up period of 3 years, patients with functioning renal grafts do not show similar progression. The incidence of solid renal tumours has been shown to be low.

Adult↗
PubMed1992

Multipoint mapping of adult onset polycystic kidney disease (PKD1) on chromosome 16.

Analysis of genetic linkage data in 33 adult onset polycystic kidney (ADPKD) families was carried out using probes for the D16S85, D16S84, and D16S94 loci. The data set of 33 families shows no evidence of genetic heterogeneity since one unlinked family was previously excluded. Two point linkage analysis showed maximum likelihood values of the recombination fraction of 0.07 for ADPKD and D16S85 (lod score 18.78), 0.02 for ADPKD and D16S84 (lod score 7.55), and 0.00 for ADPKD and D16S94 (lod score 6.73). Multipoint analysis showed a maximum likelihood order of tel-D16S85-0.06-D16S84-0.02-(PKD1, D16S94)-cen with a multipoint lod score of 32.16. Analysis of rare recombinants lying close to PKD1 gave results consistent with this order.

Chromosome Mapping↗
PubMed1992

An audit of ultrasound diagnosis of gallbladder calculi.

Many series suggest that ultrasound is an accurate method for demonstrating cholelithiasis. However, these series were often prospective and the examinations performed by experienced sonographers. This audit addresses whether the accuracy is maintained in daily practice. We reviewed the ultrasound scans of 128 patients who underwent cholecystectomy for cholelithiasis and compared the findings. The operative and ultrasound findings were at variance in eight of the 128 patients (6.2%). Five were reported as having gallstones on ultrasound but none were found at cholecystectomy, a false positive rate for ultrasound of 3.9%. Three had abnormal gallbladders with no gallstones on ultrasound but gallstones were found at operation, a false negative rate of 2.3%. To avoid false positive diagnoses, suboptimal examinations should be repeated and the scan should be repeated immediately pre-operatively if only small calculi are seen. Alternative imaging should be performed if necessary, either cholescintigraphy in the acute situation or elective oral cholecystography. Some false negative examinations may be avoided by performing repeat examinations if the gallbladder is thick-walled and tender. With these provisos we conclude that ultrasound correctly diagnoses cholelithiasis in daily practice.

Cholecystectomy↗
PubMed1992

Conventional 15 G needle technique for renal biopsy compared with ultrasound-guided spring-loaded 18 G needle biopsy.

Two techniques for percutaneous renal biopsy were retrospectively reviewed to assess their relative safety and efficacy. Ultrasound localization of the kidney by a radiologists, with subsequent biopsy performed by a renal physician using a hand-held 15 G cutting needle (Tru-Cut), was compared with biopsy performed by a radiologist using an 18 G cutting needle with a spring-loaded biopsy device (Biopty) and real-time ultrasound guidance. The smaller needle with real-time ultrasound is more reliable at retrieving an adequate specimen for histological examination (93%) than the "conventional" technique (79%). Fewer complications occurred in the Biopty group although the difference did not reach statistical significance. The average length of stay in hospital was significantly shorter for elective biopsies with the Biopty device (1.80 compared with 2.93 nights, p less than 0.01). We recommend the use of the Biopty device with an 18 G needle and real-time ultrasound guidance as the method of choice for percutaneous renal biopsy.

Adolescent↗
PubMed1992

Cricopharyngeal dysfunction.

The aim of the study was to determine the manometric patterns in dysphagic patients with radiologic evidence of upper esophageal sphincter (UES) dysfunction. Nineteen patients with radiographic abnormalities of the UES underwent measurement of several parameters of UES tonic pressure and pharyngoesophageal water swallow dynamics. At least two UES tonic pressures were elevated in six subjects, compared with a control group of 67 healthy volunteers. No patients had UES achalasia. The cricopharyngeal impression in the remaining patients may represent muscular hypertrophy or deficiency of UES opening, despite manometric relaxation, but its relationship to the patient's symptoms remains unknown. Cricopharyngeal myotomy appears to be a reasonable treatment for patients with manometric UES hypertonicity.

Adult↗
PubMed1991

Doppler colour flow imaging in peripheral arterial disease.

Duplex scanning is unique in its ability to provide both anatomical and physiological information about the circulation, but it is time-consuming and difficult to perform. Technological advances now allow the Doppler information to be colour-coded, making scanning both quicker and more accurate. This article describes the technique and potential use of Doppler colour flow imaging in the investigation and treatment of peripheral arterial disease.

Arterial Occlusive Diseases↗
PubMed1990

Ultrasound assessment of the position of the tongue during induction of anaesthesia.

Tongue position was assessed in 15 female patients at induction of anaesthesia with either thiopentone or propofol. A video recording of a midline sagittal section of the tongue was made using an ultrasound transducer placed below the chin, and representative figures analysed by an observer who was not aware of the patient's state. In 11 satisfactory recordings, the tongue movement was inconsistent in direction and not more than 8 mm in the anterior tongue and 6 mm in the posterior tongue. The movements detected did not suggest that the tongue is likely to be an important cause of airway obstruction on induction of anaesthesia.

Adult↗
PubMed1989

Pharyngoesophageal dysmotility in globus sensation.

Ambulatory esophageal pH monitoring, radiologic examination, endoscopy, and manometry were undertaken in 142 patients with globus. The results demonstrate that abnormal gastroesophageal reflux occurred in 23% of patients, implying that, while reflux may be responsible for globus in some patients, it is not the cause of globus sensation in the majority of individuals with this symptom. Comparing patients with globus and control subjects, there were no differences in lower esophageal sphincter pressures, esophageal body motility, or tonic upper esophageal sphincter pressures, but patients with globus exhibited higher pharyngeal and upper esophageal sphincter after-contraction pressures during deglutition. The physiological significance of this pharyngeal and upper esophageal dysmotility is not clear and it may be no more than a secondary phenomenon. Alternatively, it may contribute to the generation of globus, perhaps in combination with other physical and psychological triggers.

Diagnosis, Differential↗
PubMed1987

Globus sensation is not due to gastro-oesophageal reflux.

Oesophageal manometry and prolonged ambulatory pH monitoring were performed in 47 patients with the globus sensation, 48 control subjects and 28 patients with documented oesophagitis. Globus patients also underwent video-recorded barium examination and rigid endoscopy. Manometry was normal in 38 of the globus group (94%). The mean percentage time below pH 4 was 4.16 in controls, 5.11 in globus patients (NS) and 18.54 in oesophagitis patients (P less than 0.0005). Oesophageal acid exposure did not correlate with sex, smoking or heartburn and correlated with age only in oesophagitis patients (P less than 0.001). Biopsy showed mild laryngitis in 2 globus patients and distal oesophagitis in 6 (13%). Abnormal oesophageal acid exposure and distal oesophageal dysmotility are not aetiological factors in the majority of patients with globus pharyngis.

Adult↗
PubMed1987

Studies of genetic linkage between adult polycystic kidney disease and three markers on chromosome 16.

Adult polycystic kidney disease (APKD) is a common genetic disorder that is inherited as an autosomal dominant trait. Recent reports show that, in some families, the APKD gene shows close genetic linkage to two chromosome 16 specific genetic markers. We have been conducting a genetic linkage study using 29 polymorphic isoenzyme and antigenic markers in 184 members of 12 APKD families. We present here the results of linkage analysis using three of these markers which have also been reported to be located on chromosome 16: phosphoglycolate phosphatase (PGP), glutamate pyruvate transaminase (GPT), and haptoglobin (HP). The results show that APKD is closely linked to the PGP locus on the short arm of chromosome 16 (16p13----p12), which is consistent with the previously reported linkage both to PGP and to the alpha globin locus. The genetic distance between PGP and APKD shows a maximum likelihood value of the recombination fraction at zero with a lod score of 5 X 5. There is no evidence of linkage between APKD and either GPT or HP. The PGP polymorphism potentially provides a useful predictive test to complement the use of alpha globin probes in genetic counselling. These tests should provide an efficient means of primary screening of family members at risk, as well as introducing the possibility of prenatal diagnosis.

Alanine Transaminase↗