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Biomedical subjects

J M Fitzpatrick

Publications and source records attributed to J M Fitzpatrick.

At least 37 records · Page 2Linked to original sources
PubMed1990

Pulse oximetry: a new non-invasive assessment of peripheral arterial occlusive disease.

Peripheral skin perfusion reflects the level of vascularity and viability of a limb and may help in planning the site of amputation or bypass surgery in patients with vascular disease. This study used peripheral pulse oximetry in 20 healthy volunteers and in 20 patients with limb ischaemia. Pulse oximetry saturation levels (Psa,O2) were compared with ankle artery Doppler pressures and transcutaneous oxygen measurements (Ptc,O2). Recordings were taken at two standard sites distally and referenced to finger and forearm to calculate an index. A significant correlation was found between Ptc,O2 and Psa,O2 in patients with ischaemia (r = 0.68, P less than 0.01). A further group of 12 patients with acute limb ischaemia was similarly assessed before and after revascularization. After revascularization mean(s.d.) Ptc,O2 increased from 38(13) to 44(1) mmHg (P greater than 0.05) and mean(s.d.) Psa,O2 increased from 86(3) to 90(4) per cent (P less than 0.01). These data suggest that pulse oximetry is a more sensitive index of peripheral perfusion than Ptc,O2 or ankle artery Doppler pressure and that, because of its accuracy and simplicity, it merits further use.

Angioplasty, Balloon↗
PubMed1990

Free radical inhibition and serial chemiluminescence in evolving experimental pancreatitis.

Oxygen free radical activity and inhibition were examined in experimental pancreatitis. Twenty-five rats were randomized to five groups: controls received intravenous saline, to simulate pancreatitis one group received intravenous caerulein (5 micrograms kg-1 h-1), and three groups received sodium taurocholate via the pancreatic duct (0.2 ml, 5 per cent), either alone, following allopurinol or immediately before superoxide dismutase. Chemiluminescence (a phenomenon based on the emission of light during chemical reactions and which is dependent on oxygen free radical activity) was used as an index of oxygen free radical activity and was measured in tissue samples at 5-min intervals following induction of pancreatitis. The control mean(s.e.m.) serum amylase level 1 h after induction of pancreatitis was 635(13) units. It was significantly elevated in caerulein-induced pancreatitis, 1833(118) units (P less than 0.05) and exceeded 3000 units in all taurocholate-infused animals. Mean(s.e.m.) chemiluminescence ranged from 44 (8) mV 100 mg-1 at time zero to 404(113) mV 100 mg-1 at 1 h in controls. In caerulein-induced pancreatitis mean(s.e.m.) chemiluminescence peaked at 20 min (1399(239) mV 100 mg-1, P less than 0.02) and in taurocholate-induced pancreatitis at 15 min (2316(95) mV 100 mg-1, P less than 0.004). Superoxide dismutase significantly reduced chemiluminescence and hyperamylasaemia in taurocholate groups. Increasing oxygen free radical activity paralleled evolving pancreatitis. Superoxide dismutase may have a therapeutic role in pancreatitis.

Allopurinol↗
PubMed1990

The skeletal framework of human kidney and renal cell carcinoma. A scanning electron microscopic study.

The three dimensional architecture of the connective tissue framework of normal human kidney and three renal cell carcinomas was studied. A sodium hydroxide maceration technique was used to remove the cellular elements thus exposing the underlying connective tissue structures. The collagen fibrillar network was visualized using the scanning electron microscope. In normal kidney the fibres were fine, and smooth, and corresponded to the shapes of the original parenchymal constituents. The fibres of the kidney tumours were coarse in nature and irregularly distributed. The technique provides a rapid method for studying connective tissue fibres in normal and diseased tissue. The three dimensional architecture thus exposed enhances our knowledge of tumour stroma.

Carcinoma, Renal Cell↗
PubMed1990

An experimental technique for renal intrapelvic access.

This study describes an experimental technique for insertion of an indwelling cannula into the canine renal pelvis, and demonstrates its use in the measurement of pelviureteric pressure and motility, creatinine clearance, Whitaker tests, nephrostograms and nephrostomy drainage. The system, which consists of cannula, Heplock and plastic fixation disc, has been inserted into 53 canine kidneys (48) dogs, and percutaneous needle passage into the subcutaneously placed Heplock was used to gain access to the renal pelvis. This technique was successful in virtually all cases (131 separate procedures), and there were few complications. The indwelling intrapelvic cannula is a simple, cheap and reliable method of gaining longterm renal intrapelvic access in the dog, and has many experimental applications.

Animals↗
PubMed1990

Tapetool: a software tool for importing image data from image acquisition computers to image processing computers.

Currently, the image distribution gap between image acquisition computers and image processing computers is bridged through magnetic tapes. The tape formats used by the manufacturers of the image acquisition computers are idiosyncratic and fairly complex. A general purpose window based software tool is herein described, which frees the clinical and research sectors of the responsibility of understanding and decoding these complex formats in order to import image databases from acquisition computers to image processing computers. This software tool provides a cornerstone for developing image processing software for diagnostic, therapeutic and surgical planning purposes.

Algorithms↗
PubMed1990

Extracorporeal shockwave lithotripsy monotherapy for paediatric urinary tract calculi.

The role of extracorporeal shockwave lithotripsy (ESWL) in the management of paediatric urinary tract calculi was evaluated. The study group included 22 children (13 male, 9 female) with an age range of 2 to 13 years. The renal calculi, including staghorn and ureteric calculi, varied in size from 0.3 to 5 cm. Overall stone clearance at 3 months was 79% with a low incidence of complications (2 children required nephrostomy drainage for sepsis). ESWL is a non-invasive method of managing even complex stones in children of all ages, irrespective of size or position.

Adolescent↗
PubMed1990

Effects of pulmonary vascular obstruction on right ventricular afterload.

We compared the effects of three forms of vascular obstruction: positive end-expiratory pressure (PEEP), ensnarement of the left main pulmonary artery (SN), and pulmonary thromboembolism (EMB) on right ventricular afterload. We measured right ventricular and pulmonary arterial pressures and flow in open-chested dogs under anesthesia (n = 8). Pulmonary artery input impedance (Zin) was calculated by Fourier analysis of the pressure and flow waves. Characteristic impedance (Zc) and pulmonary arterial compliance (Ca) were estimated from Zin with a lumped parameter model. Although PEEP, SN, and EMB all increased mean pulmonary arterial pressure, PEEP, had negligible effect on Zc and Ca, whereas SN increased Zc but decreased Ca (+24% and -49%, respectively), and EMB decreased both Zc and Ca (-33% and -39%, respectively). These changes of Zc affect wave reflection and alter the energy transmission ratio, which is the ratio of hydraulic power output in the measured and forward waves (Wm/Wf). Under control conditions, Wm/Wf was 62% and was not affected significantly by SN (59%) or by PEEP (46%), but it fell significantly to 30% after EMB. Simulation of these experiments in a mathematical model suggested that the increase of Zc with SN was due to an active neurohumoral effect; all other responses were consistent with passive mechanical effects. In additional experiments, we tested the effects of meclofenamate (n = 6) and ketanserin (n = 6) and of atropine and vagotomy (n = 5) on the response to SN and EMB. The serotonin antagonist, ketanserin, blunted the increase of Zc to SN, but none of the interventions significantly affected the response of Zc or Ca to EMB.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Three-dimensional morphological study of the pancreatic microvasculature in caerulein-induced experimental pancreatitis.

A morphological study of the pancreatic microvasculature in experimental pancreatitis was performed in dogs, using three-dimensional scanning electron microscopy vascular casting and transmission electron microscopy. Animals with pancreatitis were characterized by a marked reduction in the number of capillaries outlined by the cast and by distortion of those that were outlined, with irregularity of the capillary lumen, abruptly terminating capillary buds and leakage of the cast material through the capillary membrane. The study provides convincing morphological evidence that one of the earliest changes in acute pancreatitis is distortion of the capillary circulation.

Acute Disease↗
PubMed1989

Prognostic value of nucleolar organizer regions and ploidy values in advanced colorectal cancer.

The prognostic value of nucleolar organizer regions and ploidy status in patients with Dukes' C colorectal cancer was determined. In addition, nucleolar organizer regions and ploidy status were compared with the established prognostic indices age, sex, tumour location and degree of histological differentiation. Fifty-one patients (27 men, 24 women) aged 35-81 years (median 64.8 years) were studied. Five years after presentation, 16 patients were alive and well. Survivors had significantly lower nucleolar organizer region counts (median value and range) in primary tumours 12 (8-15) and lymph node metastases 11 (8-15) than non-survivors 17 (14-25) and 18 (13-25) respectively (P less than 0.05). Fewer survivors had aneuploid tumours than non-survivors: four survivors compared with 17 non-survivors. In a regression analysis model, nucleolar organizer regions were the most important individual variable for predicting survival (chi2 = 15, P less than 0.01) while ploidy values (chi2 = 6, P less than 0.2) were equivalent to histological differentiation.

Adult↗
PubMed1989

Diurnal insulin and glucose profiles following transplantation of fresh and cryopreserved canine pancreatic islets.

Dispersed islet autotransplants (fresh and cryopreserved) can produce normal fasting insulin and glucose concentrations. Following an intravenous glucose challenge, however, the insulin response is impaired and glucose clearance delayed. This study examines the diurnal insulin and glucose response to feeding in recipients of fresh islet autografts (n = 6), recipients of cryopreserved islet autografts (n = 3), normal unoperated controls (n = 10) and insulin treated pancreatectomized diabetic dogs (n = 7). Mean fasting insulin and glucose levels were similar in all groups. After feeding, insulin profiles in both transplant groups were near normal while significant hyperinsulinaemia occurred in insulin treated diabetic dogs. Mild postprandial carbohydrate intolerance was observed in transplant recipients but glycosylated haemoglobin levels were similar (mean(s.d.] to normals (6.88(0.86) per cent, 6.86(0.5) per cent respectively). Dispersed islet autotransplantation with portal insulin delivery produces near normal insulin and glucose profiles suggesting that this may represent a suitable treatment for insulin dependent diabetes.

Animals↗
PubMed1989

Endoscopic treatment of urinary tract calculi.

Removal of urinary tract calculi by endourological techniques is now widely practised and has reduced the indications for open surgical removal to a minority of cases. A review of 270 consecutive patients who presented to the Meath Hospital Urology department with urinary tract calculi and were treated by percutaneous or transurethral endoscopy is herein reported. The rates of successful clearance of renal (95%) and ureteric (78%) calculi compare well with previous reports. The majority of complications were minor and a low overall complication rate was experienced at ureterorenoscopy. In our experience, endourological treatment of urinary tract calculi is successful, efficient and safe and is the recommended approach to urinary tract calculi that require surgical intervention.

Adult↗
PubMed1989

Renal injury and recovery in partial ureteric obstruction.

Partial ureteric obstruction was produced by insertion of an obstructing stent into the left ureter of 21 mongrel dogs and the duration of obstruction was varied as follows: Group A (n = 7) for 60 days; Group B (n = 7) for 28 days; Group C (n = 7) for 14 days. Intrapelvic pressure monitoring confirmed that obstruction had been produced by stent insertion and relieved by reimplantation of the left ureter following the designated obstruction period. The extent of recovery of renal function was assessed by creatinine clearance, with group C maintaining normal function, group B recovering 31% and group A recovering 8% of control function. Methyl-methacrylate extrusion casts of the renal microvasculature were made in group B and C kidneys and studied by scanning electron microscopy. During obstruction there was evidence of arteriolar constriction. These changes provide a morphological basis for the renal functional alterations and support the concept that post-obstructive renal failure is a vascular injury.

Animals↗
PubMed1989

The Whitaker test: experimental analysis in a canine model of partial ureteric obstruction.

The Whitaker test has been described as a means of reaching a diagnosis in equivocal upper urinary tract obstruction, but there has been conflicting evidence regarding the validity of this test. The present study assesses the reliability of the test in an experimental model which creates an accurate and predetermined degree of partial obstruction of the ureter. The Whitaker test was performed using the standard perfusion rate of 10 ml./min. in male adult dogs using a long-term indwelling renal intrapelvic cannula before and after application of ureteric obstruction, and after one month. Control animals underwent a sham procedure. Results of in vivo and in vitro perfusion studies were compared. Perfusion studies at multiple flow rates were also performed. The Whitaker test reliably detected the presence of ureteric obstruction and the degree of partial obstruction could be determined. Multiple flow rate studies did not significantly improve test results. Provoked pressures in the highest grade of obstruction were less than expected and this may be due to pyelovenous reflux.

Animals↗
PubMed1989

Extracorporeal shock wave lithotripsy with the Lithostar lithotriptor.

Early experience of extracorporeal shock wave lithotripsy (ESWL) using the Lithostar lithotriptor is reported; 145 patients underwent 185 treatments for 189 stones. Treatments were performed with either intravenous sedation and analgesia (90%) or general anaesthesia (10%). There were 123 renal calculi, 44 ureteric calculi and 22 staghorn calculi. Stone fragmentation was achieved with 1724 +/- 1035 shocks at 19 kv. The immediate stone fragmentation rate was 90% and the 3-month clearance rate 88%. Secondary treatments were required in 19% of patients and additional procedures in 17%. A comparison between stone size and the number of shock waves required to achieve stone fragmentation revealed a linear relationship. The Lithostar is a very effective second generation lithotriptor which can be used for renal, staghorn and ureteric calculi in situ, without manipulation.

Adolescent↗