Biomedical subjects

D C Price

Publications and source records attributed to D C Price.

At least 37 records · Page 2Linked to original sources

PubMed1990

A replicated five cluster MMPI typology of morbidly obese female candidates for gastric bypass.

This study clusters empirically into subgroups the preoperative MMPI profiles of morbidly obese females seeking a gastric bypass, assesses the replicability of clusters across different subject populations and tests the hypotheses that cluster inclusion bears a significant relationship to weight loss and post-operative follow-up behavior. One hundred seventy women participated: 85 were patients at The University of Texas Health Science Center at San Antonio, Texas (UTHSCSA), and 85 were from the Cherryhill Medical Surgical Center (CMSC), Albion, Michigan. A hierarchical cluster analytic technique was applied using the cosine measure and average linkage within groups method. Purification of the two samples resulted in seven groups with 59 cases in the UTHSCSA sample and six groups with 62 cases in the CMSC sample. Five groups containing 94 subjects (55 percent) replicated across the two samples (UTHSCSA = 44; CMSC = 50). Discriminant analysis yielded four statistically significant functions. The chi 2 test was employed to discern significant differences based on group inclusion. Demographic differences between the two geographic samples are discussed. One year follow-up studies found that personality type bears a significant relationship to indexed weight loss, follow-up appointment frequency, and follow-up duration for the San Antonio sample.

Adult↗

PubMed1989

Use of a fibre-optic hydrophone in measuring acoustic parameters of high power hyperthermia transducers.

A fibre-optic hydrophone consisting of a polarisation-maintaining fibre carrying light from a laser source has been used to measure the acoustic output parameters of a single focused hyperthermia transducer and a six-transducer assembly. Beam profiles of the transducers were measured using the fibre-optic hydrophone and the results compared with those obtained using a PVDF hydrophone. The acoustic power output from the hyperthermia transducer was measured using a radiation force balance. It was observed that the root mean square voltage of the fibre-optic hydrophone output is proportional to the square root of the acoustic power up to more than 80 W. It was also observed that, under continuous-wave operation, the fibre optic hydrophone can stand up to very high power (more than 200 W) without being damaged. As its sensing element is the fibre itself, whose diameter is considerably narrower than the width of the ultrasonic beam, it can provide resolution of about 80 microm in beam profile measurement. The fibre is a line sensor and a computer tomographic technique is used to recover the pressure profile from the hydrophone output voltage. In typical clinical operations, the six-transducer assembly is driven with less than 150 W of electrical power input. In such cases, each individual transducer receives less than 25 W of input power and non-linearity and generation of high frequency harmonics at the focus is not a significant problem.

Acoustics↗

PubMed1989

Rapid, contrast-enhanced, diuretic magnetic resonance imaging of unilateral partial ureteral obstruction. An experimental study in micropigs.

The value of rapid, contrast-enhanced, diuretic magnetic resonance (MR) imaging (using ferrioxamine B and furosemide) in demonstrating partial unilateral ureteral obstruction and the potential of such MR imaging in differentiating obstructive from nonobstructive hydronephrosis was assessed in six micropigs. MR imaging (0.35 Tesla, partial-flip technique with repetition time [TR] of 125 milliseconds, echo-delay time [TE] of 20 milliseconds, and flip angle of 70 degrees) was performed before, and at 5, 12, and 19 days after partial ureteral obstruction. Additionally, MR images were acquired 5, 12, and 19 days after release of obstruction. The diuretic was injected 10 minutes after the contrast medium. MR findings were correlated with results from nuclear scintigraphy (99mTc-DMSA uptake). MR images provided good morphologic detail from which renal size, parenchymal thickness, and degree of hydronephrosis could be determined. Contrast medium allowed assessment of cortical uptake and urinary excretion. The course of cortical signal enhancement best characterized the difference between obstructive and nonobstructive hydronephrosis. Normal kidneys and kidneys with nonobstructive hydronephrosis showed progressive decrease in cortical signal enhancement (-11.7% within 40 minutes) after furosemide injection. The kidneys with obstructive hydronephrosis demonstrated a plateau of signal enhancement without decrease (-0.7% within 40 minutes). These results demonstrate the utility of rapid contrast-enhancing, diuretic MR imaging in differentiating obstructive from nonobstructive hydronephrosis.

Animals↗

PubMed1989

Noncontrast and contrast enhanced MR imaging in the evaluation of partial ureteral obstruction: an experimental study in the micropig.

Twelve Yucatan micropigs (3 controls; 3 sham-operated; 6 with unilateral obstruction) were studied to assess the value of noncontrast and contrast-enhanced (Gadolinium-DTPA) magnetic resonance (MR) imaging in the evaluation of partial ureteral obstruction. MR findings were correlated with findings of quantitative (Tc-99m-DMSA) scintigraphy, and histology. On noncontrast T1-weighted images, the normal porcine kidney demonstrated good corticomedullary contrast (CMC = 16.8% +/- 5.0). Five minutes after administration of Gd-DTPA, there was enhancement of the renal cortex (+24.4% and medulla (+46.2%), and CMC was no longer discernible. Enhancement of the urine within the collecting system (+119.1%) was also observed. The obstructed kidneys demonstrated marked thinning of the renal parenchyma and decreased signal intensity on noncontrast T1- and T2-weighted images (P less than 0.01). Urine in the dilated collecting system did not differ significantly from urine in controls except in the three animals with urinary tract infection (P less than 0.05). Five minutes following injection of Gd-DTPA, there was enhancement of the renal parenchyma in all kidneys. Excretion was seen in three pigs and no excretion in two. Thus, useful information can be obtained in partial ureteral obstruction from both pre-contrast and Gd-DTPA-enhanced MR images of the kidney.

Animals↗

PubMed1988

Localization of abscess in adult polycystic kidney by indium-111 leukocyte scan.

In patients with adult polycystic kidney disease (APKD) infected cysts are difficult to localize with current radiographic techniques, especially those dependent on renal function. Indium-111 leukocyte (In-WBC) imaging is both highly sensitive and effective in detecting and localizing abscesses in patients with renal failure. We report on a patient with APKD and sepsis in whom computed tomography, ultrasound, and physical examination failed to locate the renal abscess, which was found by In-WBC scanning.

Abscess↗

PubMed1988

Complete and partial ureteral obstruction: evaluation of renal effects with P-31 MR spectroscopy and Tc-DMSA scintigraphy.

Phosphorus-31 magnetic resonance (MR) spectroscopy was used to study the effects of partial and complete ureteral obstruction on the porcine kidney; results were compared with renal tubular function as determined with technetium-99m dimercaptosuccinic acid (DMSA) scintigraphy. Twenty-seven pigs were used: nine as sham-operated controls, six with partial ureteral obstruction, and 12 with complete ureteral obstruction. P-31 MR spectra and Tc-DMSA scintiscans were obtained weekly over 3 weeks. Partial obstruction caused no significant change in P-31 MR spectra, whereas Tc-DMSA scintiscans showed a 74% decrease in tubular function by the end of 3 weeks. Complete obstruction caused a 43% reduction in the mean adenosine triphosphate (ATP) to inorganic phosphate (Pi) ratio, which paralleled the 96% decrease in Tc-DMSA uptake over 3 weeks. The difference in ATP/Pi ratios between control and completely obstructed kidneys was significant (P less than .01) at 2 and 3 weeks after ligation. These results indicate that radionuclide Tc-99m DMSA uptake is very sensitive to the pathophysiologic changes in renal tubular function, while the organ average cellular bioenergetic state (ATP/Pi) is not as strongly affected.

Adenosine Triphosphate↗

PubMed1987

Assessment of clinical renal preservation by phosphorus-31 magnetic resonance spectroscopy.

To evaluate the role of magnetic resonance spectroscopy (MRS) and to develop surface coils for assessing cadaveric renal viability during hypothermic storage, we used the monophosphate/inorganic phosphate ratio (MP/Pi) to monitor phosphorous metabolites in intact kidneys during various renal preservation maneuvers. Eighteen canine kidneys and 16 cadaveric kidneys were studied as follows: Group 1 (N = 4) in situ kidneys were monitored by implanted MRS coils; Group 1 (N = 4) ex vivo kidneys were immediately attached to vascular cannulas and monitored by MRS surface coils during normothermic perfusion; Group 3 (N = 4) kidneys were removed, cold-flushed and, after 24 hours of 4C storage, monitored by MRS surface coils before and during four hours of reperfusion via vascular cannulas; Group 4 (N = 6) kidneys were removed, cold-flushed and monitored by surface coils during cold storage up to 72 hours. In addition, 16 cadaveric kidneys were studied while in sterile cold-storage containers. Postoperative renal function was followed in recipient patients. The MP/Pi ratios in Group 1 kidneys correlated with the ability to regenerate adenosine triphosphate (ATP). Groups 2 and 3 showed similar regeneration of ATP and MP/Pi after postischemic reperfusion, and the signal-to-noise ratios of the surface coils were better than those in the implanted coils in Group 1. Surface-coil monitoring in Group 4 kidneys showed predictable decay rates of MP/Pi during one to 72 hours of cold storage; in contrast, simultaneous cortical medullary microcirculation studies with 99mTc-macroaggregated albumin were inconclusive. Human cadaveric kidneys with high MP levels were associated with excellent renal function after transplantation, while those with low MP (less than or equal to 0.50) were associated with nonviability. We conclude that MRS is a practical and safe diagnostic modality for clinical transplantation.

Adenosine Triphosphate↗

PubMed1987

Liquid thickness vs. vertical pressure gradient in a model of the pleural space.

In recent studies using relatively noninvasive techniques, the vertical gradient in pleural liquid pressure was 0.2-0.5 cmH2O/cm ht, depending on body position, and pleural liquid pressure closely approximated lung recoil (J. Appl. Physiol. 59: 597-602, 1985). We built a model to discover why the vertical gradient in pleural pressure is less than hydrostatic (1 cmH2O/cm). A long rubber balloon of cylindrical shape was inflated in a plastic cylinder. The "pleural" space between the balloon and cylinder was filled with blue-dyed water. With the cylinder vertical, we measured pleural pressure by a transducer through side taps at 2-cm intervals up the cylinder. The pressure was measured with different amounts of water in the pleural space. With a clear separation between the balloon and the container, the vertical gradient in pleural liquid pressure was hydrostatic. As water was withdrawn from the pleural space, the balloon approached the wall of the container. Over an 8-cm-long midregion of the model where the balloon diameter matched the cylinder diameter, the vertical gradient was not hydrostatic and was virtually absent. In this region, the pleural liquid pressure was uniform and equal to the recoil of the balloon. In this section we could not see any pleural space. By scintillation imaging using 99mTc-diethylenetriamine pentaacetic acid in the water, we estimated the thickness of this flat "costal" pleural space to be approximately 20 microns. Radioactive tracer injected at the top of the pleural space appeared by 24 h at the bottom, which indicated a slow drainage of liquid by gravity.(ABSTRACT TRUNCATED AT 250 WORDS)

Body Fluids↗

PubMed1986

Intracoronary platelet aggregation: pattern of deposition after ischemia, cardioplegia, and reperfusion.

Platelet deposition in the coronary microvasculature has not been completely defined in the temporal relationship to acute myocardial ischemia, the application of crystalloid cardioplegia, and during reperfusion on heart bypass. Twenty-two canine hearts were serially biopsied for the analysis of radioactively tagged platelets. Eleven hearts underwent an isolated heart support preparation with seven followed by potassium cardioplegic arrest and reperfusion while the remaining 4 were maintained on continuous bypass. All 11 hearts undergoing bypass experienced transient (less than 90 sec) ischemia during bypass preparation and produced platelet aggregation in the myocardium (51.12 +/- 24.0 as compared to nonischemic control group 12.3 +/- 4.7; P = 0.005). Potassium cardioplegia did not completely wash out these platelets to the nonischemic control levels (27.8 +/- 14.9; P = 0.04). With the onset of reperfusion after 1 hr of cardioplegic arrest, platelet radioactivity profoundly increased (133.3 +/- 72.8; P = 0.0101) and remained high throughout the hour of reperfusion (324.7 +/- 269.3; P = 0.0369). In summary, intracoronary platelets are activated after transient ischemic episodes during initiation of heart bypass. These ischemia-activated platelet aggregations persist despite the application of cardioplegia during the arrest period. This deposition, in turn, allowed an ongoing pattern of platelet aggregation during the early and subsequent reperfusion. This pattern of ischemia-activated platelet aggregations probably accounts for the progressive reperfusion injury and support of an antiplatelet treatment for coronary microvasculature protection.

Animals↗

PubMed1986

Prevention of ischemia-induced myocardial platelet deposition by exogenous prostacyclin.

The antithrombotic effects of prostacyclin infusion on myocardial platelet deposition were studied in a canine model during and after global ischemia. Eleven isolated heart preparations were subjected to 1 hour of cardioplegic arrest under moderate hypothermia (27 degrees to 28 degrees C), including a control group (n = 7) and a prostacyclin-treated group (n = 4). The hearts of four other dogs were continuously perfused for 180 minutes. Platelet deposition was measured at 15 minute intervals throughout the 3 hour study. Serial full-thickness myocardial biopsy specimens were analyzed for activity of 111In-labeled platelets with 99mTc-labeled erythrocyte correction for tissue blood content. The pattern of platelet distribution was determined by scintiscans of each heart, taken with a gamma camera at the end of the 60 minute reperfusion period. Substantial myocardial platelet deposition was found in the control hearts after ischemia but not in the prostacyclin-treated group (p less than 0.05). Furthermore, prostacyclin infusion had a significant disaggregatory effect on intracoronary platelet deposits when the precardioplegic and postcardioplegic biopsy specimens were analyzed (p less than 0.05). Three hours of continuous perfusion did not increase tissue 111In-labeled platelet activity. Ex vivo images showed platelet deposition to be a diffuse patchy process with significantly more 111In activity in the endocardium than in the epicardium after global ischemia (p less than 0.05). These data show the potent antithrombotic properties of prostacyclin in preventing and disaggregating ischemia-induced intracoronary platelet deposition during and after cardioplegic arrest.

Animals↗

PubMed1986

Total hepatic arterial perfusion after occlusion of variant lobar vessels: implications for hepatic arterial chemotherapy.

The surgical placement of hepatic arterial cannulas, followed by intra-arterial chemotherapy, is a promising technique for the treatment of unresectable hepatic malignancies. Complete perfusion of the liver with drugs is essential, but may be difficult to achieve in some patients with variant arterial anatomy. In 79 patients, we encountered 15 with variant anatomy that precluded standard single or dual cannulation techniques. In 12 patients variant lobar arteries were ligated at surgery. Postoperative transarterial coil occlusion was used in three patients. In each case, the remaining hepatic lobar artery was perfused with a single catheter. Complete bilobar hepatic perfusion was documented by a technetium 99m macroaggregated albumin scan in 13 of 15 (87%) patients. Of patients scanned more than 5 days after occlusion, six of six (100%) had full perfusion of the region supplied by the variant lobar vessels. Postocclusion hepatic arteriography demonstrated translobar collateral vessels that provided perfusion of the region of the occluded variant artery. There was no added morbidity from lobar arterial occlusion and no disparity in tumor response between perfusion by direct cannulation and perfusion by collateral flow. Occlusion of variant hepatic lobar arteries in conjunction with single catheter cannulation to infuse the remaining lobar vessels is a useful technique to provide total hepatic arterial perfusion in patients with variant hepatic arterial anatomy.

Adult↗

PubMed1985

Avoidance of gastroduodenal toxicity in patients receiving hepatic arterial 5-fluoro-2'-deoxyuridine.

Gastroduodenal inflammation and ulceration have been frequently observed in patients receiving continuous hepatic arterial infusions of 5-fluoro-2'-deoxyuridine (FUDR) for liver malignancy. Thirty-five patients with metastatic colon cancer received hepatic arterial FUDR administered with implanted infusion pumps. At surgery, particular care was taken to identify and divide those vessels arising from the hepatic arteries distal to the point of cannulation that supplied the superior border of the distal stomach and proximal duodenum. None of the patients developed signs or symptoms of gastritis or ulcer attributable to chemotherapy. We contend that gastritis and ulcer in patients receiving hepatic arterial FUDR are due to misperfusion of drug into the upper gastrointestinal tract and that these complications can be largely avoided by use of appropriate surgical techniques.

Colonic Neoplasms↗

PubMed1985

Prostacyclin production in regions of arterial stenosis.

The effect of abnormal flow dynamics on prostacyclin (PGI2) production by intact endothelium is unknown. To investigate this we studied the effects of graded stenoses on vessel wall PGI2 production in dogs (n = 8) whose femoral and carotid arteries (n = 32) were narrowed by machine-milled clips, producing 1.0 cm segmental stenoses of 25%, 50%, 75%, and 90% diameter reduction. Three dogs were injected with Indium 111-labeled platelets and 12 vessels were scanned for platelet deposition. All stenotic vessels were excised at 6 weeks for histologic study (hematoxylin-eosin section and immunohistochemistry for factor VIII) and PGI2 radioimmunoassay (as the metabolite 6-keto PGF1 alpha). All vessels remained patent with no thrombus formation in any segment. Vessel imaging in platelet-labeled animals showed no significant deposition. Histologic analysis demonstrated an intact endothelial surface in the stenotic segments, confirmed by the demonstration of factor VIII production by these cells. PGI2 production (per unit surface area) by the arterial segments with greater than or equal to 50% stenosis markedly exceeded the PGI2 production by the normal proximal and distal segments (p less than 0.0002) and showed further significantly increased production with increasing degrees of stenosis (p less than 0.00001). The data indicate increased PGI2 production by normal endothelium in regions of arterial stenosis. The mechanism of this increase is unknown, but this endothelial "turn on" effect may serve to inhibit deposition of platelets and thrombus formation in the presence of disordered flow patterns.

Animals↗

PubMed1984

A comparative study of skin blood flow in musculocutaneous and random pattern flaps.

The present study in dogs was performed to evaluate the development of blood flow in cranial-based, rectus abdominis musculocutaneous (MCF) and random pattern (RPF) flaps and in adjacent intact skin before and after operation. Prior to raising of the flaps the intact skin area had the same blood flow in all the test injections. Following flap elevation blood flow in the MCF increased and on the second postoperative day (POD) it was 2.6 times the preoperative value. From POD 2 through POD 15 only minor changes were found for blood flow in MCF. Blood flow in the RPF immediately after surgery was only 31% of the preoperative value and 24% of the MCF value. After POD 2-3 blood flow in RPF, however, increased and reached the preoperative level and continued to increase through POD 15. Intact adjacent skin showed changes similar to those of MCF through POD 6, however, by POD 15 blood flow had decreased and was lower than that in MCF and RPF. Blood flow rates at remote sites in the groin and shoulder were identical and showed only a slight increase during the first two postoperative days. It is concluded that MCF have an early and continuous increase in blood flow after raising, while RPF have an early decrease. RPF, however, develop a subsequent increase in flow lasting through POD 15. Intact adjacent skin also showed increased blood flow which could not be attributed to a generalized increase in skin blood flow.

Animals↗

PubMed1984

Site of deposition and factors affecting clearance of aerosolized solute from canine lungs.

We determined the influence of several factors on lung solute clearance using aerosolized 99mTc-diethylenetriaminepentaacetate. We used a jet nebulizer-plate separator-balloon system to generate particles with an activity median aerodynamic diameter of 1.1 micron, administered the aerosol in a standard fashion, and determined clearance half times (t1/2) with a gamma-scintillation camera. The following serial studies were performed in five anesthetized, paralyzed, intubated, mechanically ventilated dogs: 1) control, with ventilatory frequency (f) = 15 breaths/min and tidal volume (VT) = 15 ml/kg during solute clearance; 2) repeat control, for reproducibility; 3) increased frequency, with f = 25 breaths/min and VT = 10 ml/kg; 4) positive end-expiratory pressure (PEEP) of 10 cmH2O; 5) unilateral pulmonary arterial occlusion (PAO); and 6) bronchial arterial occlusion (BAO). Control t1/2 was 25 +/- 5 min and did not change in the repeat control, increased frequency, or BAO experiments. PEEP markedly decreased t1/2 to 13 +/- 3 min (P less than 0.01), and PAO increased it to 37 +/- 6 min (P less than 0.05). We conclude that clearance from the lungs by our method is uninfluenced by increased frequency, increases markedly with PEEP, and depends on pulmonary, not bronchial, blood flow.

Aerosols↗

PubMed1983

Cadmium, zinc, and copper metabolism in the mottled mouse, an animal model for Menkes' kinky hair syndrome.

Studies of uptake and release of 64Cu, 109Cd, and 65Zn in suckling C57BL/6J male mice revealed kinetics and distributions that differed for each metal both within and among the organs analyzed, suggesting distinct, albeit overlapping, mechanisms for transport and binding of each metal. In mutants, there were tissue-specific increases in copper-binding capacity. In hemizygotes (Moblo/y) accumulation of 64Cu was increased in kidney, lung, and duodenum. In heterozygotes (Moblo/+), 64Cu content was increased in kidney, with a smaller increase in lung, and no change in duodenal Cu. Decreased 64Cu accumulation was seen in liver in both hemi- and heterozygotes. In contrast, 64Zn and 109Cd accumulation in organs of heterozygote mice was not significantly distinguishable from normal. In skin and connective tissues there is excessive accumulation of 64Cu in Moblo/+ and Moblo/y, no abnormality in heterozygote 65Zn accumulation, but a clear decrease in heterozygote 109Cd content. In both mutant kidney and liver, there was an aberrant subcellular distribution of 64Cu, with the major fraction of sequestered 64Cu in the cytosol. Our studies establish that in spite of the ubiquity of metallothioneins and the structural similarities of those that have been characterized, there is specificity and functional heterogeneity in metal binding among tissues. The aggregate data suggest that there are unique regulatory mechanisms for the metabolism of copper and zinc, while there exists, in part, an inverse relationship between the binding of copper and cadmium. Our data further suggest that the blotchy mutation involves a specific cytosolic copper storage or transport protein also capable of binding cadmium.

Animals↗

PubMed1983

Vessel wall and indium-111-labelled platelet response to carotid endarterectomy.

Postendarterectomy platelet deposition and thrombus formation may play an important role not only in vessel wall healing but also in the small incidence of postoperative cerebral ischemia and postoperative stenosis. A study has been performed using a canine model to investigate the healing response to carotid endarterectomy and the validity of an in vivo indium-111 (In-111) radiotracer technique in the assessment of postendarterectomy deposition of autologous labelled platelets. Sixteen endarterectomized carotid arteries showed uptake of autologous In-111 platelets immediately after infusion, reaching a maximum by 1 hour with little increase at 24 or 48 hours. No uptake was seen in ten control vessels following platelet infusion (P less than 0.05). At autopsy, seven vessels were demonstrated to have In-111 platelet deposition immediately prior to sacrifice of the animals. Postmortem scanning confirmed the localization to the vessel lumens, and microscopy revealed thrombus formation with or without partial endothelialization. Complete reendothelialization had occurred in the vessels that failed to show platelet deposition. Delayed healing was associated with continuing platelet deposition, excessive thrombus formation, and luminal stenosis. Arteriotomy closure with a vein patch altered the healing characteristics of the vessel with segmental thrombus formation over the vein patch. A preliminary study of the postendarterectomy in vivo In-111 platelet response in humans demonstrated platelet deposition that was not influenced by the administration of antiplatelet drugs at currently prescribed levels.

Animals↗

PubMed1981

Detecting and localizing peripheral arterial disease: assessment of 201Tl scintigraphy.

Detection and localization of peripheral arterial disease was evaluated by intravenous injection of 201Tl at peak exercise in 22 subjects. Images of the gluteals (G), thighs (T), knees (K), and calves (C) were obtained at exercise and after a 3 hr delay, and stored in a computer, interextremity (T/T and C/C) and intraextremity (G/T, T/C, T/K) counts ratios were calculated. Normal values were defined in 11 control subjects and compared with those obtained in 11 patients with angiographically proven peripheral arterial disease. Bilateral disease was detected scintigraphically in all patients. T/T and G/T ratios correctly predicted proximal disease in nine of 12 limbs, while C/C, T/C, T/K ratios correctly predicted distal disease in 21 of 21 involved limbs. Delay images 3 hr after stress generally reverted towards the norm. Objective systematic evaluation of limb isotope uptake permits accurate detection and localization of peripheral arterial disease. Method accuracy compares favorably with physical signs and with other noninvasive methods of detection of peripheral vascular disease. Scintigraphy presents advantages which indicate great clinical potential.

Adult↗