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Biomedical subjects

J G Wright

Publications and source records attributed to J G Wright.

At least 163 records · Page 9Linked to original sources
PubMed1989

Laser angioplasty for limb salvage: observations on early results.

During a 27-month period laser thermal angioplasty (LTA) was attempted in 15 patients who had totally occluded segments of their superficial femoral--popliteal arteries (SFA) with limb-threatening ischemia (rest pain or tissue necrosis). In five patients (33%) laser perforation of the SFA precluded successful angioplasty, and those five patients have been excluded from further analysis. In the remaining 10 patients the prelaser angiogram demonstrated an average SVS/ISCVS runoff score of 7.7 (best possible score, 1; worst possible score, 10). Seven patients (70%) had occlusions of all infrapopliteal arteries. All 10 patients were available for clinical follow-up, and follow-up angiograms were available for eight patients (80%). Clinical failure was defined as recurrence of the clinical signs or symptoms for which the LTA was performed. After 6 months of follow-up clinical failures occurred in nine patients (90%). Four patients had no clinical improvement. Five patients had transient clinical improvement after LTA, and all subsequently had early recurrence of symptoms. The average time from LTA to recurrence of symptoms was 1.7 months. Seven patients had subsequent bypasses or amputations an average of 2.2 months after laser angioplasty. The SFA patency rate by life-table analysis was 25% at 6 months. The single patient with clinical success (at 12 months) had no tibial vessel disease evident on his prelaser angiogram, and he underwent a concomitant inflow procedure at the time of his LTA. We believe that the disappointing results in this small series of patients can be attributed to tibial vessel disease that was not addressed by this technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Heparin decreases ischemia-reperfusion injury in isolated canine gracilis model.

The mechanisms of ischemia-reperfusion injury in skeletal muscle remain controversial. Some investigators have demonstrated that heparin can ameliorate ischemic injury to heart, brain, and renal tissue. We investigated the ability of heparin sodium to decrease ischemia-reperfusion injury in an isolated gracilis muscle model in ten anesthetized mongrel dogs. One gracilis muscle was perfused normally while the contralateral muscle was subjected to six hours of ischemia followed by one hour of reperfusion. Five dogs were given a preischemic bolus of heparin sodium (200 U/kg, intravenously followed by a continuous infusion (15 U/kg/h, intravenously), and five control dogs received no heparin. Quantitation of skeletal muscle ischemia-reperfusion injury was determined by histochemical staining with triphenyl tetrazolium-chloride and computerized planimetry of the infarct size. Results from the ischemic muscle demonstrate a significant beneficial effect of heparinization. The nonheparinized dogs had a 72% +/- 5% infarct size, which was significantly reduced to 24% +/- 8% in the heparinized dogs. The mechanism of this protective effect may be due to heparin's anticoagulant, antiplatelet, or anti-inflammatory action.

Acute Disease↗
PubMed1988

Rate of reperfusion blood flow modulates reperfusion injury in skeletal muscle.

The mechanisms of ischemia-reperfusion (I-R) injury in skeletal muscle remain controversial. We investigated the effect of the rate of reperfusion blood flow on I-R injury in an isolated in vivo canine gracilis muscle model in six anesthetized dogs. In all animals, both gracilis muscles were subjected to 6 hr of ischemia followed by 1 hr of reperfusion. During reperfusion, one gracilis artery was partially occluded to limit the rate of reperfusion blood flow to its preischemic rate (limited reperfusion, LR), while the contralateral artery was allowed to perfuse freely at a normal rate (normal reperfusion, NR). Muscle injury was quantified by histochemical staining (triphenyltetrazolium chloride, TTC) with computerized planimetry of the infarct size, and by spectrophotometric determination of technetium-99m pyrophosphate uptake. Endothelial permeability was quantified by measurement of gracilis muscle weight gain and 125I-albumin radioactivity after intravenous injection. Results are presented as the means +/- SEM, and differences are considered to be statistically significant if P less than 0.05 by Student's t test for paired data. LR resulted in significantly less blood flow (9.7 +/- 1.7 cc/min/100 g) when compared to NR (55.7 +/- 11.6 cc/min/100 g). I-R injury was significantly reduced by LR as evidenced by a decrease in TTC infarct size from 41 +/- 7% to 11 +/- 5%, and a decrease in technetium-99m pyrophosphate uptake from 512 +/- 20 to 163 +/- 44 X 10(3) counts/min/g. LR also significantly decreased the postreperfusion edema formation as evidenced by a reduction in the muscle weight gain from 27 +/- 6 to 9 +/- 1 g, and a reduction in the 125I-albumin radioactivity from 45 +/- 14 to 32 +/- 8 counts/min/g. These data suggest that the hyperemic rate of reperfusion blood flow is a significant factor in the pathophysiology of postreperfusion edema and that clinical control of reperfusion injury in skeletal muscle may be achieved by limiting the rate of reperfusion blood flow.

Animals↗
PubMed1988

A new quantitative spectrophotometric assay of ischemia-reperfusion injury in skeletal muscle.

Characterization of ischemia-reperfusion injury of skeletal muscle remains poorly defined. A new quantitative assay to measure ischemic skeletal muscle injury is described and validated in a rat hindlimb model. This biochemical spectrophotometric technique measures triphenyltetrazolium chloride reduction in ischemic muscle. The reduction assay demonstrated significant injury after 3 hours of ischemia (25.4 +/- 9.7 percent of control activity; p less than 0.05). More severe injury occurred after 4 or more hours (less than 3 percent of control activity; p less than 0.05). This assay is an objective and quantitative method for characterizing ischemia-reperfusion injury.

Animals↗
PubMed1988

Regional hypothermia protects against ischemia-reperfusion injury in isolated canine gracilis muscle.

Regional hypothermia is known to protect many tissues from ischemic injury. We investigated the relationship between regional hypothermia and skeletal muscle ischemia-reperfusion injury in a bilateral in vivo isolated canine gracilis muscle model. In five anesthetized dogs, one gracilis muscle was subjected to 6 hours of ischemia followed by 1 hour of reperfusion while the contralateral muscle served as a nonischemic control. Localization and quantitation of skeletal muscle injury was determined by histochemical staining with triphenyl tetrazolium chloride (TTC) followed by computerized planimetry of the infarct size. Muscle pH and temperature were monitored continuously in the proximal, middle, and distal segments by using pH electrodes and needle thermistors. Muscle pH was calculated by use of the Nernst equation with temperature correction, and hydrogen ion washout rates (H+) were derived from the observed change in muscle pH during reperfusion. A significant (p less than 0.05) regional hypothermia was observed in the distal third of the muscle. The preischemic temperature in the distal muscle was 27 +/- 2 degrees (SEM) C, compared to 34 +/- 1 degree and 32 +/- 2 degrees C in the proximal and middle segments of muscle, respectively. This temperature gradient was sustained throughout the experiment. The distal third of the ischemic muscle demonstrated significantly less (p less than 0.05) injury than the proximal and middle thirds as measured by TTC infarct size (31 +/- 10%, compared to 71 +/- 3% and 78 +/- 6%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Fibrinolysis during normal human pregnancy: complex inter-relationships between plasma levels of tissue plasminogen activator and inhibitors and the euglobulin clot lysis time.

Although it has been previously considered that blood fibrinolytic capacity is reduced during pregnancy, this has been disputed. Also the mechanisms underlying any change in fibrinolysis in pregnancy require clarification. We have therefore measured the plasma activity of tissue plasminogen activator (t-PA) and inhibitors (t-PAi) and the concentration of the pregnancy specific inhibitor (PA12) antigen, as well as the euglobulin clot lysis time (ECLT) during normal pregnancy. Plasma concentrations of fibrinogen, plasminogen, fibrin(ogen) degradation products (FDP) and cross-linked products (D-dimer) were also monitored. We confirm a marked reduction of the fibrinolytic activity of the plasma euglobulin fraction from the second trimester, and a parallel reduction in t-PA and increase in t-PAi activities, with rapid return to non-pregnant levels post-partum. In contrast, PAI2, whilst undetectable in non-pregnant control plasma, was already measurable in the first trimester, increased through pregnancy, and remained at a high concentration up to at least 48 h post-partum. Fibrinogen and plasminogen concentrations rose progressively through pregnancy and FDP and D-dimer were frequently detectable in late pregnancy plasma. Changes in the ECLT and plasma t-PA and t-PAi activities in pregnancy cannot therefore be directly related to the concentration of PAI2 antigen. Also, despite the apparent marked reduction in fibrinolytic capacity fibrin(ogen) breakdown products are frequently present in increased plasma concentrations in late pregnancy.

Female↗
PubMed1988

Heparinization reduces endothelial permeability and hydrogen ion accumulation in a canine skeletal muscle ischemia-reperfusion model.

Skeletal muscle injury after revascularization (ischemia-reperfusion) continues to be a major clinical problem. Although heparinization has been recommended, its action in an experimental model of I-R has not been evaluated. We investigated the ability of heparinization to decrease I-R injury in 10 anesthetized dogs (nonheparinized, n = 5; heparinized, n = 5), subjecting one gracilis muscle to 6 hours of ischemia followed by 1 hour of reperfusion while the identically prepared contralateral muscle served as a nonischemic control. Skeletal muscle infarction was determined by Tc-PYP uptake. Endothelial permeability was quantified by measurement of skeletal muscle 125I-Alb activity after intravenous injection. Interstitial hydrogen ion (H+) accumulation was determined by a miniature pH electrode inserted into the gracilis muscle. Isotopic activities from the ischemic muscle were calculated as a percentage of the contralateral nonischemic muscle (mean +/- SEM). Nonheparinized ischemic muscles had an increase in the activities of Tc-PYP and 125I-Alb of 684% +/- 149% and 742% +/- 130%, which were reduced to 218% +/- 54% and 378% +/- 85% by heparinization, respectively (p less than 0.05). During ischemia, the nonheparinized muscles accumulated 1223 +/- 121 nmol of H+ compared with 785 +/- 95 nmol in the heparinized animals (p less than 0.01). This significant reduction in I-R injury may be causally related to diminished endothelial permeability and H+ accumulation.

Animals↗
PubMed1987

Multivariate discriminant analysis of risk factors for operative mortality following isolated coronary artery bypass graft. Loyola University Medical Center experience, 1970 to 1984.

The Loyola Open-Heart Registry is a fully operational database that contains detailed data on approximately 9,000 patients who have undergone coronary bypass or cardiac valve replacement from January 1970 to December 1984. We analyzed the registry data using multivariate discriminant analysis to identify and quantitate those factors that might predict operative mortality (OM) for patients undergoing coronary artery bypass grafts at Loyola University Medical Center: Operative mortality was defined as death within 30 days following surgery. A total of 50 clinical and angiographic variables were analyzed for possible univariate association with operative mortality. Twenty-two variables were found to have significant univariate association with OM, and these 22 variables were subjected to multivariate discriminant analysis. For patients undergoing isolated, elective coronary artery bypass, the factors found to be predictive of OM are age (greater than 70) (F = 11.57), severe (more than six stenoses) coronary artery disease (F = 5.81), diffuse disease (F = 5.54), positive family history (F = 5.17), and number of coronary arteries bypassed (F = 4.78).

Coronary Artery Bypass↗
PubMed1985

A database management system for cardiovascular disease.

The Loyola Open-Heart Registry is a fully operational database that has hundreds of programs designed to input, modify, verify, maintain, update and analyze its raw data. It contains retrospectively collected data on approximately 4000 patients who underwent coronary bypass (CABG) or cardiac valve replacement (CVR) from January 1970 to May 1981. Since 1981 we have collected detailed information on approximately 1300 patients per year. The system is described in clinical and technical terms. The means of data acquisition and input are described and a flow chart for the collection of data is provided. The system's hardware is described briefly, and the nature and limitations of the software are discussed. Specific datasheets are described, and examples of output retrievals are provided. A few comments are made regarding the administrative aspects of database management. The entire paper is summarized, and our future plans and areas of development are described.

Cardiovascular Diseases↗
PubMedDate not supplied

Measuring disability of the upper extremity: a rationale supporting the use of a regional outcome measure.

OBJECTIVE: Many existing upper extremity outcome measures have been designed for a specific anatomic site (e.g., shoulder) or a specific disease entity (e.g., carpal tunnel syndrome). The purpose of this paper is to examine whether questionnaire items taken from very specific measures are considered relevant only to that specific region or are applicable to the whole extremity. METHODS: Fifteen practicing clinicians categorized a sample of 132 items from existing questionnaires according to whether the items reflected disability specific to an anatomic site or were relevant to the whole extremity. RESULTS: Seventy-two percent of the items were categorized as relevant to the extremity as a whole, while only 21% of the items were categorized as specific to an anatomic site. CONCLUSION: Items in existing specific upper extremity questionnaires are also relevant to other regions and conditions. This finding is in agreement with kinesiologic and biomechanical theories that the upper extremity acts as a single functional unit. Questionnaires designed for the whole extremity could provide a more practical and still valid measure of upper extremity disability.

Activities of Daily Living↗
PubMedDate not supplied

The treatment of supracondylar fractures in children with an absent radial pulse.

The purpose of this study was to determine the outcome of patients with a supracondylar fracture and an absent radial pulse. All children with displaced extension-type supracondylar fractures from 1984-1992 were eligible. Of 326 children with supracondylar fractures, 22 had an absent radial pulse on admission. Fifteen of the 22 children had a well-perfused hand after closed reduction and K-wire fixation. Five had no pulse but a well-perfused hand after reduction and immobilization of the elbow in slight flexion; none had any problem at final review. Seven patients who had a cold white hand after closed reduction received open reduction of fracture and arterial exploration. In conclusion, the initial treatment for children with displaced supracondylar fractures with an absent radial pulse should be closed reduction, K-wire fixation, and immobilization in < 90 degrees of flexion. Children who have a well-perfused hand but an absent radial pulse after satisfactory closed reduction do not necessarily require routine exploration of the brachial artery.

Child↗