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Biomedical subjects

B Finlayson

Publications and source records attributed to B Finlayson.

At least 19 recordsLinked to original sources
PubMed1991

Decreasing the risk of human immunodeficiency virus or hepatitis B virus infection during endoscopic surgery.

The risk of transmission of human immunodeficiency virus and hepatitis B virus infection is small but finite. Urological surgeons are exposed through needle punctures in open surgery and splashes during endoscopic surgery. Safety glasses are difficult to use during endoscopic surgery and they do not offer complete protection. The Steri-Shield, a facial shield designed to be fixed to the endoscope, is described.

Endoscopes↗
PubMed1991

Interaction energies in the coagulation of calcium oxalate monohydrate.

In the present work, Gregory's approximation was used to calculate the Hamaker constant (A131) for the van der Waals interactions between calcium oxalate monohydrate (COM) particles in water. An average value of 1.135 (+/- 0.341) x 10(-20) J for A131 was calculated for COM particles at 37 degrees C in aqueous solutions. Theoretical calculations predicting coagulation behavior based on the calculated A131 are consistent with experimental data.

Calcium Oxalate↗
PubMed1990

Extracorporeal shock-wave lithotripsy in horseshoe kidneys.

Using the Dornier HM-3 lithotriptor, 10 patients (11 renal units) with calculi in horseshoe kidneys were treated with extracorporeal shock-wave lithotripsy (ESWL) and ancillary procedures. Six renal units (55%) underwent pre-ESWL manipulation consisting of a Double J stent, ureteral catheter, or percutaneous nephrostomy. The "blast path" was employed to treat five renal units which could not be positioned at F2. Good initial stone fragmentation was obtained in eight renal units (73%). There were two episodes of post-ESWL obstruction requiring intervention; both occurred in the same patient. A total of seven post-ESWL procedures were performed on two renal units. After all procedures, eight renal units (73%) were rendered stone-free, six (55%) with ESWL alone. The average follow-up interval was twelve months (range 1-28 months). ESWL can be used effectively to treat some patients with calculi in horseshoe kidneys. The ectopic location of these renal units may make it difficult to position calculi at F2, thus necessitating treatment on the blast path or placement of the patient in prone position. Multiple ancillary procedures may be necessary.

Adult↗
PubMed1989

A model system for assessing physicochemical factors affecting calcium absorbability from the intestinal tract.

An in vitro model system was utilized to critically examine physicochemical factors that could play a role in determining the amount of potentially absorbable ionic calcium as well as soluble complexes in the proximal jejunum following ingestion of tricalcium dicitrate, calcium carbonate, or tricalcium diphosphate. The solubility of calcium salts (500 mg calcium each) was tested in 300 ml water containing varying amounts of hydrochloric acid (0, 0.72, 2.4, 7.26, and 24.2 mEq) intended to mimic achlorhydric to peak acid secretory states. Whereas 20% of calcium citrate dissolved in the absence of hydrochloric acid, a negligible amount of calcium carbonate and calcium phosphate underwent dissolution. In solutions containing 0.72-7.26 mEq hydrochloric acid, calcium citrate was more than twofold soluble than calcium carbonate, and calcium phosphate had intermediate solubility. At simulated peak acid secretion, all three salts were completely soluble, or nearly so. To simulate pancreatic bicarbonate secretion, the filtrates obtained from solubility studies were titrated to pH 5, 6, and 7 with sodium hydroxide. Reprecipitation of calcium citrate and calcium carbonate did not occur. However, substantial calcium phosphate reprecipitation took place especially at high pH and in filtrates derived from high hydrochloric acid content. In filtrates derived from reprecipitation experiments (at pH 6 and 7), anionic complexation of calcium was calculated in order to estimate the amount of ionic and complexed calcium. Considerable amount of calcium from dissolved calcium citrate was complexed (60-65%), principally as soluble CaCit-, whereas calcium complexation was negligible in the calcium carbonate and calcium phosphate systems.

Anions↗
PubMed1989

Use of retrograde lavage catheter during ESWL treatments.

Use of a retrograde lavage catheter utilizing a Water-Pik for the removal of stone fragments during an extracorporeal shock-wave lithotripsy (ESWL) treatment is described. Three of 4 patients treated to date have been essentially stone-free at the end of their ESWL treatment. Urinary extravasation and ureteral stricturing have not occurred.

Adult↗
PubMed1989

Overview of surgical treatment of urolithiasis with special reference to lithotripsy.

In the early 1980s, 2 elegant innovations were added to open surgery in the management of stones: endourology and extracorporeal shock wave lithotripsy. The decision strategy for treating stones is not yet codified and it depends on several factors, such as equipment, type and size of stones, needs of the patient and skills of the surgeon. After open stone surgery convalescence lasts approximately 4 to 6 weeks and repeated surgery is more difficult. With endourology convalescence can be reduced to a few days in an uncomplicated case, the risk of complication is approximately 10 per cent and retreatment is not more complicated. Convalescence with extracorporeal shock wave lithotripsy often is negligible and some extracorporeal shock wave lithotripsy units are run on an outpatient basis. However, as with all stone surgeries, extracorporeal shock wave lithotripsy causes renal bleeding of varying degrees. There are reports of diastolic hypertension after extracorporeal shock wave lithotripsy in up to 8 per cent of the patients. Retreatment is easy but the late consequences of retreatment are unknown. Extracorporeal shock wave lithotripsy is the dominant means of surgical management for stones in the western world; 87 per cent of our patients are treated with extracorporeal shock wave lithotripsy and 4 per cent with open surgery.

Humans↗
PubMed1989

Renal transplantation: a 20-year experience at the University of Florida.

Substantial gains have been made in both patient and graft survival during 20 years of transplanting kidneys at the University of Florida. The number of transplant recipients yearly has increased from six in 1966 to more than 100 in 1986. The use of immunosuppression reflects our evolving understanding of transplant immunology, with current morbidity and mortality rates considerably improved over those of the early years. This paper summarizes our transplantation experience over the past two decades.

Adolescent↗
PubMed1989

Use of the computer program EQUIL to estimate pH in model solutions and human urine.

The computer program EQUIL was designed to calculate relative supersaturations of solute components of common urinary stones. In an extended software version, quantitative consideration of charge balance for a priori or a posteriori pH estimation was added. The reliability of this computation was tested with hydrogen ion titration of buffer solutions containing HEPES [N-(2-hydroxyethyl)piperaizine-N'-ethanesulfonic acid] as well as samples of normal human urine. In the model solutions with HEPES, the difference between calculated pH values and the measured pH was smaller than 1.2% for any titration step within the buffer zone (pH 8.5-6.8). The pH values calculated for whole urine differed from the measured pH by 7% to 53%, and the calculated charge inbalance ranged from 2.6 to 9.6 mM. This net cation inbalance indicates that there is a need to account for other anionic components, including hippurate, amino acids, and isocitrate. In experimental solutions, charge balance calculations with EQUIL can be of great utility because they permit a priori estimation of pH or computation of the composition at a desired pH.

Buffers↗
PubMed1988

Extracorporeal shock-wave lithotripsy (ESWL). I. In vitro results of blast path treatment of human gallstones.

To evaluate the efficacy of extracorporeal shock-wave lithotripsy (ESWL) for human gallstone fragmentation, biliary calculi of different size and composition were evaluated to determine clinical applicability of this technique. Human biliary calculi composed primarily of cholesterol (Group I, N = 6) and calcium bilirubinate (Group II, N = 6) were shocked in vitro at varying positions along the ESWL blast path. All calculi subjected to lithotripsy were fragmented. Cumulative fragment size was less than or equal to 2, 3, 5, and 8 mm in 73, 86, 94, and 100% of all stones treated, respectively. No statistically significant differences were observed following stone fragmentation when the two groups were compared. Further, no statistically significant differences were evident when comparing the energy expended during fracture of stones in the two groups, or in comparison of fracture with old or new electrodes. However, when fragmentation for stone remnants less than or equal to 2 mm in size was compared at 6- and 10-cm positions on the blast path, a statistically significant difference was noted (P less than 0.001). Stone fragmentation was greatest at positions closest to F2. These data indicate that biliary calculi can be fragmented when subjected to lithotripsy and positioned on the ESWL blast path.

Cholelithiasis↗
PubMed1988

Extracorporeal shock-wave lithotripsy (ESWL). II. In vivo canine results of blast path treatment of human gallstones.

To evaluate the role of ESWL in vivo for the treatment of human gallstones positioned on the blast path, a canine model was developed to determine the efficacy of stone fragmentation and the subsequent histopathological injury that occurs as a result of this therapeutic technique. Twenty-four 16- to 20-kg mongrel dogs were divided into five groups: I: ESWL without stone, autopsy at 48 hr (N = 6); II: ESWL with stone (mean diameter 16.8 mm, range = 14-19 mm), autopsy at 48 hr (N = 10); III: ESWL without stone, autopsy at 41-46 days (N = 6); IV: ESWL without stone, autopsy immediately after ESWL (N = 1); V: No ESWL or stone, autopsy 2 hr after anesthesia induction (N = 1). A human gallstone (96% cholesterol) was inserted by cholecystotomy (N = 10) in Group II only. All groups (N = 24) had operative placement of a 6.5 Fr accordion catheter into the gallbladder for radiographic visualization. For each blast path treatment, 2000 discharges were delivered at 18-24 kV. Histopathologically, the Group V gallbladder served as a control. Groups I, II, and IV revealed mild subacute injury; dog gallbladders in Group III showed regression of these changes. Total surface area (TSA) of Group II stones increased from a pre-ESWL mean of 6.60 +/- 0.0.84 cm2 to 53.84 +/- 26.8 cm2 post-ESWL (P less than 0.001). Cumulative post-ESWL fragment sizes for particles in less than or equal to 2-, less than or equal to 3-, less than or equal to 5-, less than 10- and greater than or equal to 10-mm categories represented 32.9, 41.6, 49.4, 74.3, and 100% of pretreatment stone weight, respectively. These data indicate that human gallstones can be fractured to a variable degree when treated on the ESWL blast path and that TSA increased significantly. Gallbladder histopathologic changes appear to be reversible by 41-46 days post-ESWL.

Animals↗
PubMed1988

Simulation of ventilatory-induced stone movement and its effect on stone fracture during extracorporeal shock wave lithotripsy.

Because ventilation influences renal movement, we investigated the effect of stone motion on the efficiency of extracorporeal shock-wave lithotripsy (ESWL). Comparisons of the rates of fragmentation of an experimental model of renal calculi were made between simulated high-frequency jet ventilation at 100 breaths/min. with four-mm. stone movement as measured from the fluoroscope screen, conventional mechanical ventilation at 10 breaths/min. with 32-mm. stone movement as measured from the fluoroscope screen, and a static control. Fragmentation did not differ significantly between high-frequency jet ventilation and no ventilation (static control), but was significantly greater with high-frequency jet ventilation than with conventional ventilation.

High-Frequency Jet Ventilation↗
PubMed1988

Combination extracorporeal shock wave lithotripsy and percutaneous extraction of calculi in a renal allograft.

Renal calculi are a well documented although uncommon complication of kidney transplantation and may be associated with significant morbidity in this immunosuppressed population with a single functioning kidney. We describe a patient who presented with 2 episodes of staphylococcal bacteremia associated with a ureteral structure and struvite calculi involving the calices, renal pelvis and proximal ureter of a cadaveric renal allograft. The patient was treated successfully with a combination of extracorporeal shock wave lithotripsy, percutaneous extraction and balloon dilation of the ureteral stricture. Renal transplant function was not altered postoperatively. In selected cases shock wave lithotripsy can be used as effective adjunctive therapy in a renal allograft harboring stones.

Combined Modality Therapy↗
PubMed1987

ESWL: a look from different angles.

Rapid and accurate stone positioning prior to shock wave administration is the key to efficient extracorporeal shock wave lithotripsy (ESWL). On the Dornier HM-3 machine, the operator uses the control panel to move the stone image along the x, y, or z axis, but many operators are uncertain about the direction and speed of the target when the control buttons are activated. Since knowledgeable, full use of ESWL controls probably results in reduced positioning time and x-ray exposure, the angles and relative velocities from simple and complex maneuvers are presented as a didactic aid.

Humans↗
PubMed1987

Pathologic effects of ESWL on canine renal tissue.

The introduction of extracorporeal shock wave lithotripsy (ESWL) has provided an avenue for dealing with many urinary stones noninvasively. The margin of safety for the kidney during shock wave administration is largely undefined. A pilot study was performed where six kidneys in five female mongrel dogs were shocked. Group A kidneys were given 1,776, 4,500, 6,000, or 8,000 shocks, respectively, at 18-24 kV. Group B kidneys received 1,600 and 8,000 shocks (18-24 kV). The number of shocks per electrode ranged from 500 to 4,538 and averaged 2,490. The dogs were sacrificed forty-eight to seventy-two hours (Group A) or twenty-eight to thirty-two days (Group B) post-treatment. Modest damage (hematoma and/or interstitial hemorrhage) was noted in all kidneys. Evidence of permanent change (fibrosis) was noted in both Group B kidneys. Complete necrosis of the kidney was not seen after administration of 8,000 shocks. These preliminary data indicate that lithotripsy can, in some circumstances, produce renal damage in the canine model.

Animals↗