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Biomedical subjects

B W Thompson

Publications and source records attributed to B W Thompson.

At least 19 recordsLinked to original sources
PubMed1994

Wound healing in forefoot amputations: the predictive value of toe pressure.

A retrospective study of 136 men undergoing forefoot amputation was done to test the hypothesis that preoperative toe pressure (TP) could predict the likelihood of wound healing. Demographic data included age, smoking history, diabetes mellitus (DM), hypertension, hyperlipidemia, and coronary artery disease. Clinical data included infection, preoperative arterial Doppler data, TP, wound disposition, concomitant revascularization (REV), and healing outcome. Among diabetics, no primary amputation healed with a preoperative TP < 38 mm Hg. Among REV diabetics, no healing occurred with a TP < 40 mm Hg after bypass, but no failures occurred either with a TP > 68 mm Hg or an increase in TP > or = 30 mm Hg after bypass. Nondiabetic patients exhibited no threshold TP values. Univariate analysis revealed that DM and REV were significantly different in the healed (N = 83) vs. nonhealed (N = 53) populations (p = 0.027 and 0.034). In healed patients mean TP (71.8 +/- 3.5 mm Hg SEM) was significantly higher than in nonhealed patients (45.1 +/- 4.3 mm Hg SEM, p = 0.000). Logistic regression analysis identified age > 60 years (p = 0.03), DM (p = 0.003), preoperative TP (p < 0.001), and REV (p < 0.001) as significant independent predictors of forefoot amputation healing. Healing probability was calculated and plotted vs. TP for subpopulations based on age, DM, and REV status for both primary forefoot amputation and amputation concomitant with bypass. In this study population, therefore, preoperative TP appeared to be a useful clinical tool for predicting the healing potential of both primary forefoot amputations and amputations plus concomitant bypass for any given patient.

Adult↗
PubMed1994

Carotid-subclavian bypass: a twenty-two-year experience.

PURPOSE: A retrospective review of 124 patients who underwent carotid-subclavian bypass from 1968 to 1990 was done to assess primary patency and symptom resolution. METHODS: Preoperative data included age, atherosclerosis risk factors, and indications for surgery. Perioperative data included mortality and morbidity rates and graft conduit. Postoperative follow-up assessed graft patency, resolution of symptoms, and late survival. RESULTS: Age ranged from 42 to 78 years (mean 57.9). Indications for surgery were vertebrobasilar insufficiency in 24 (19%), extremity ischemia (EI) in 33 (27%), transient ischemic attacks (TIAs) in 13 (11%), both vertebrobasilar insufficiency and EI in 31 (25%), and both TIAs and EI in 23 (18%) patients. Graft conduits were polytetrafluoroethylene in 44 (35%) and Dacron in 80 (65%) cases. Concomitant ipsilateral carotid endarterectomy was done in 32 (26%) patients. During operation, death occurred in one patient (0.8%), and complications occurred in 10 (8%) patients. Thirty-day primary patency and symptom-free survival rates were 100%. Long-term follow-up ranging from 5 to 164 months was available for the 60 cases done between 1975 and 1990. Three grafts occluded at 30, 36, and 51 months after surgery for a primary patency rate of 95% at 5 and 10 years. Twenty-two patients died, yielding survival rates of 83% at 5 years and 59% at 10 years. Symptom recurrence occurred in six (10%) patients from 9 to 66 months after surgery. The symptom-free survival rate was 98% at 1 year, 90% at 5 years, and 87% at 10 years. Symptoms recurred in three patients with occluded grafts and three with patent grafts. The preoperative symptoms of drop attacks and TIAs did not recur. EI recurred in 5% and was noted only in the presence of graft occlusion. Dizziness recurred in 17% of patients admitted with this symptom and was observed despite graft patency. CONCLUSION: Carotid-subclavian bypass was a safe and durable procedure for relief of symptomatic occlusive disease of the subclavian artery. Long-term symptomatic relief appeared particularly likely in patients with drop attacks or upper extremity ischemia.

Adult↗
PubMed1994

Colour duplex ultrasound: a screening modality for femoropopliteal disease in patients with intermittent claudication.

In patients presenting with intermittent claudication, Colour Duplex Ultrasound (CDU) examination of the femoro-popliteal segment has been proposed as a screening modality. Those patients with atheromatous lesions suitable for percutaneous transluminal angioplasty (PTA) could proceed to diagnostic angiography. Patients with long segment occlusive disease demonstrated by CDU, who were not considered suitable candidates for surgery, would not require angiographic examination. This prospective study was performed on 46 limbs in 25 consecutive patients who presented for investigation of claudication. There was close correlation between the two methods in the demonstration of high-grade stenoses and occluded segments. Using angiography as the 'gold standard' this study indicated a diagnostic accuracy for CDU of 93% with a sensitivity of 89% and a specificity of 95%. Angiography tended to show longer occluded segments than CDU. Colour Duplex Ultrasound shows promise as a screening investigation in patients with intermittent claudication to detect lesions that may be suitable for PTA.

Aged↗
PubMed1993

Results of venous thrombectomy in the treatment of deep vein thrombosis.

Despite the infrequent use in the United States, venous thrombectomy seems to have a beneficial effect in carefully selected patients with acute iliofemoral thrombosis. The final decision to proceed with venous thrombectomy should be based on a balanced analysis of two factors--the characteristics of the thrombus and the characteristics of the patient. First, the diagnosis of acute deep vein thrombosis must be unequivocally established preoperatively. Accurate anatomic localization is usually achieved with venography, but duplex Doppler examination may be sufficient in selected instances. Second, the distribution of thromboses should be determined. Venous thrombectomy should be considered only in instances of deep vein thrombosis involving the iliofemoral venous segment. Thrombectomy for venous thrombosis below the inguinal ligament has not been consistently beneficial. Third, the age of the thrombus should be estimated. This can usually be accomplished though a careful analysis of the clinical history, but may be corroborated by duplex Doppler or venographic features of the thrombus. Venous thrombectomy should rarely be attempted if the age of the thrombus is thought to be greater than 72 hours. Unfortunately, in many instances the clinical history substantially underestimates the actual age of the underlying thrombus. Fourth, patient characteristics must be assessed preoperatively. While venous thrombectomy can usually be accomplished using local anesthesia, substantial shifts in fluid and acid base balance may be poorly tolerated by elderly, frail patients. In the setting of widespread metastatic disease, rethrombosis rates may be too high to justify thrombectomy in some patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Femoral Vein↗
PubMed1991

Recurrent intracaval renal cell carcinoma: the role of intravascular ultrasonography.

The presence of extension into the vena cava does not preclude curative resection for extensive renal cell carcinomas. However, preoperative assessment of (1) the proximal extent of the tumor and (2) the degree of adherence within the vena cava is necessary to plan operative strategies. The following report describes the successful use of intravascular ultrasonography in the preoperative evaluation of a patient with recurrent renal cell carcinoma with vena caval extension.

Carcinoma, Renal Cell↗
PubMed1990

Tissue plasminogen activator followed by percutaneous transluminal coronary angioplasty: one-year TIMI phase II pilot results. TIMI Investigators.

The TIMI phase II pilot study enrolled 288 patients with acute myocardial infarction who were treated with recombinant tissue plasminogen activator (rt-PA) within 4 hours of symptom onset and who were assigned to coronary angioplasty of the infarct-related vessel 18 to 48 hours after rt-PA treatment. The patients were followed to ascertain (1) vital status; (2) whether they suffered a recurrent myocardial infarction; (3) whether they received coronary angioplasty or bypass grafting; and (4) whether they were rehospitalized for a cardiac event. Risk factors for these events or combination of these events were identified and reported. The estimated 6-week, 6-month, and 1-year cumulative event rate of death or myocardial infarction was 9.1 +/- 1.7%, 12.9 +/- 2.0%, and 13.6 +/- 2.0%, respectively. With the exception of repeat hospital admissions, most of the above cardiac events occurred early during the patients' follow-up course. Cox proportional hazard analyses revealed that continuing chest pain after rt-PA administration, history of congestive heart failure, low systolic blood pressure at the time of initial evaluation, and history of hypertension increased the risk of death or recurrent myocardial infarction, while a history of chest discomfort at baseline evaluation and older age was predictive of future hospitalization or a revascularization procedure.

Angioplasty, Balloon, Coronary↗
PubMed1990

Traumatic left renal artery stenosis managed with splenorenal bypass: case report.

Splenorenal arterial bypass is a well established technique for the treatment of left renal artery occlusive disease. The following is a case report of the use of splenorenal bypass in the management of concomitant traumatic left renal artery intimal dissection and splenic laceration. Arteriographic and intraoperative findings are presented as well as a review of pertinent literature.

Humans↗
PubMed1990

Is routine duplex examination after carotid endarterectomy justified?

Routine follow-up of patients after carotid endarterectomy with duplex scanning is commonly practiced, yet the clinical significance of identifying those with asymptomatic restenosis is unclear. To address this issue we reviewed 120 consecutive patients who underwent 143 carotid endarterectomies from August 1983 to December 1988. One hundred one patients (118 operations) were available for clinical follow-up, and the overall incidence of recurrent symptoms was 6% (6/101). Sixty-three of these patients (78 carotid endarterectomies) had postoperative duplex examination. Two had evidence of residual disease from the time of surgery and were not included in further analysis. Significant recurrent stenosis (greater than 50% diameter reduction) developed in 14 of the remaining 76 arteries (18.2%). Twelve of 14 stenoses remained asymptomatic during follow-up from 18 to 72 months (mean 47.0 months) and did not undergo reoperation. Recurrent ipsilateral hemispheric symptoms developed in two patients with restenosis (14.3%). Four of the 62 arteries without significant recurrent stenosis developed ipsilateral symptoms (6.5%), but none required reoperation during follow-up from 1 to 71 months (mean 31.6 months). Life-table analysis showed no increased risk of transient ischemic attack, stroke, or death in patients with restenosis. This study supports regular clinical follow-up after carotid endarterectomy with emphasis on patient education in the recognition of symptoms. Although duplex scanning may be useful to follow known contralateral asymptomatic disease or evaluate those with recurrent symptoms, its routine use to identify patients with asymptomatic restenosis after carotid endarterectomy may be unnecessary.

Aged↗
PubMed1989

Improvement of flow-cytometric detection of multidrug-resistant cells by cell-volume normalization of intracellular daunorubicin content.

To improve the ability of flow cytometry to detect multidrug-resistant cells, we studied the extent to which cell volume heterogeneity accounts for the variance of intracellular daunorubicin (DNR) content. For P388 murine or HL-60 human leukemia cells exposed to DNR (1 micrograms/ml, 60 min), log intracellular DNR content varied in direct proportion to log cell volume measured by flow cytometry, with a correlation coefficient of .9. This relationship was confirmed by cell sorting based on intracellular DNR content with subsequent volume determination of the sorted cells. Normalization of intracellular DNR content for cell volume (thus obtaining intracellular DNR concentration) was accomplished by subtracting log cell volume from log intracellular DNR content for each cell. This resulted in a 34% decrease (range 23-58%) in standard deviation compared to DNR content measurements without volume normalization for all cell types tested. Following exposure to DNR (as above), intracellular DNR content of drug-sensitive P388 or HL-60 cells measured by flow cytometry was 12- and 8-fold greater than that of the multidrug-resistant sublines P388/ADR and HL-60/AR, respectively. However, because of the variance of intracellular DNR content, the predictive value of flow-cytometric determination of intracellular DNR content as a discriminant assay for detecting the frequency of drug-resistant cells in a mixed population was acceptable only when the frequency of resistant cells in the population exceeded 10%. In contrast, volume normalization of intracellular DNR content enhanced the ability of the flow-cytometric assay to discriminate resistant cells by 10-fold for P388 cells and 100-fold for HL-60 cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Serial noninvasive studies do not herald postoperative failure of femoropopliteal or femorotibial bypass grafts.

We performed a 5-year retrospective case-control study of 232 patients undergoing femoropopliteal (n = 188) or femorotibial (n = 44) bypass to determine if serial noninvasive studies herald postoperative graft failure. We correlated serial ankle/arm pressure indices (API) with graft patency. An interval drop in API of greater than or equal to 0.20 was considered hemodynamically significant, but interventional therapy was carried out only for clinically symptomatic graft failure and an API less than 0.20 above the preoperative value. The cumulative 5-year limb salvage rate was 82% and the patient survival was 63%. A significant drop in API did not correlate with cumulative 5-year graft patency. The 5-year cumulative primary graft patency rates were 60% and 62% in patients with stable and interval drops in API, respectively (Z = 0.15, p = N.S.) These results suggest that a significant drop in postoperative API does not predict patients with impending femoropopliteal or femorotibial graft failure. We believe that routine noninvasive surveillance and prophylactic intervention on detected asymptomatic lesions in leg bypass grafts may not be justified.

Adult↗
PubMed1988

Isolation of highly multidrug-resistant P388 cells from drug-sensitive P388/S cells by flow cytometric cell sorting.

To investigate the spontaneous frequency of occurrence of stable multidrug-resistant cells in a population of drug-sensitive cells, we exposed drug sensitive P388/S cells to daunorubicin (dnr) for 1 h, then used fluorescence-activated cell sorting based on intracellular dnr fluorescence to isolate cells within P388/S having different intracellular content of drug. One of the sort windows chosen (low dnr content sort window) isolated only P388/S cells with intracellular drug content equal to or less than that of the known multidrug-resistant subline P388/adr. This sort window constituted approximately 3% of P388/S cells with lowest dnr content. By such a procedure we were able, on one of seven attempts, to isolate and cultivate stable, highly multidrug-resistant cells (comparable to that of P388/adr) from the P388/S cells obtained from the low dnr-content sort window. Net growth of cells in culture was observed 15-20 days after sorting, indicating that of the P388/S cells collected from the low dnr-content sort window, very few were actually highly drug-resistant. On no occasion could resistant cells be cultivated from cells sorted from P388/S with higher dnr content, as would be expected if mutation to a multidrug-resistant phenotype had occurred as a result of exposure to drug. The resistant cells isolated from P388/S by sorting (called P388/LoSort) displayed low intracellular accumulation of dnr that was enhanced by verapamil, were cross-resistant to vincristine and actinomycin-D, and distinct from P388/S, possessed a 150- to 160-kD membrane species identified by Vinca alkaloid photoaffinity labeling.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Human percutaneous laser angioplasty. Patient selection criteria and early results.

Percutaneous transluminal laser angioplasty is a new method for treating atherosclerotic disease previously not amenable to routine percutaneous transluminal angioplasty techniques. Our results compared favorably with other clinical trials. Patient selection criteria include lesions in the superficial femoral or popliteal system not capable of being treated with routine percutaneous transluminal angioplasty. We think that these lesions include high-grade stenoses or short segmental occlusions. Heavily calcified vessels and long segment occlusions measuring greater than 12 cm in length are probably not amenable to percutaneous transluminal laser angioplasty. The long-term results of this form of therapy for peripheral vascular disease remain unknown.

Aged↗
PubMed1987

Repair time for oncogenic transformation in C3H/10T1/2 cells subjected to protracted X-irradiation.

With exponential cultures of C3H/10T1/2 cells, we have investigated the effect of X-ray dose protraction on oncogenic cell transformation in the dose range 0.25-2 Gy. Within a particular experiment a constant exposure time was used. In different experiments exposure time varied between 1 and 5h. Cell transformation was analysed using the linear-quadratic relation, gamma (D) = alpha 1D + alpha 2D2, between transformation frequency per surviving cell and X-ray dose. Based on values of the linear coefficients, we developed an empirical formula for relating slopes of dose induction curves obtained at high or reduced dose rate condition. Our estimate of repair half-time for cell transformation with 95 per cent confidence limits is 2.4 (1.8, 3.0) h.

Animals↗
PubMed1987

Transsphincteric approach to lesions of the rectum.

Transsphincteric posterior resection of villous adenomas and small carcinomas restored gastrointestinal continuity and preserved continence in 25 of 26 patients in this study. No patient had local recurrence. This procedure is suitable for villous tumors that are too high for transanal or too low for transabdominal resection, and for small mobile malignancies of the lower 5 cm of the rectum.

Adenoma↗
PubMed1986

A double beta-lactam combination versus an aminoglycoside-containing regimen as empiric antibiotic therapy for febrile granulocytopenic cancer patients.

The double beta-lactam combination of moxalactam plus piperacillin was compared with the aminoglycoside-containing regimen of moxalactam plus amikacin in a prospective, randomized trial of empiric therapy for 302 febrile episodes in granulocytopenic cancer patients. The moxalactam/piperacillin regimen was found to be as effective as the moxalactam/amikacin regimen (70 percent overall responses); responses with moxalactam/piperacillin and moxalactam/amikacin were similar for microbiologically documented infections (24 of 37, 65 percent, versus 20 of 35, 57 percent), for the subgroup with bacteremias (19 of 32 versus 14 of 28), and for clinically documented infections (41 of 58, 71 percent, versus 40 of 48, 83 percent). Responses were similar also for bacteremia in patients with persistent, profound (less than 100/microliter) granulocytopenia. Among profoundly (less than 100/microliter) granulocytopenic patients with gram-negative bacteremia, an increase in the granulocyte count to more than 100/microliter during therapy and a peak bactericidal activity of 1:16 or more (the latter noted in seven of nine moxalactam/piperacillin trials and six of nine moxalactam/amikacin trials) correlated with a favorable clinical response in 85 percent (p less than or equal to 0.00003) and 92 percent (p less than or equal to 0.044), respectively. Although serious side effects were minimal with either regimen, the double beta-lactam combination was associated with significantly less frequent nephrotoxicity (two of 145 versus 12 of 130; p less than or equal to 0.003) and ototoxicity (none of 34 versus seven of 34; p less than or equal to 0.006). The double beta-lactam combination of moxalactam plus piperacillin was found to be as effective as moxalactam plus amikacin but to have significantly less nephro- and ototoxicity.

Adolescent↗
PubMed1986

111 In-labeled leukocytes in the detection of prosthetic vascular graft infections.

Making a clinical diagnosis of infection in prosthetic vascular grafts is difficult but when undiagnosed, this condition has a high mortality rate. Using Indium-111-labeled white-blood cells, 30 scans were performed in 21 patients suspected of having a prosthetic graft infection. The diagnosis of infected graft was confirmed by surgery in all cases, and lack of infection was established by resolution of symptoms with conservative therapy. Twenty-four hour scans of autologous Indium-111 leukocytes were obtained, and correlative CT studies were done in 11 cases. There were 13 infected grafts at surgery (purulent material present), and scans were positive in all (100% sensitivity); of 17 scans, there were 15 true negatives and two false positives (88% specificity). Using the criteria of gas or fluid around the graft, the sensitivity of CT was only 37% in a small subset of these patients. One-half of the cases in which infection was suspected clinically had no infection and had negative scans. Various types of grafts and graft materials were used, and there was no correlation with presence or absence of infection on the basis of the type of graft. Extragraft infection sites were found in five patients. In conclusion, use of Indium-111 leukocytes has been found to be an accurate and valuable diagnostic method for evaluation of suspected prosthetic vascular graft infection, and to have higher diagnostic accuracy than CT.

Aged↗
PubMed1986

Metabolism of ara-C by blast cells from patients with ANLL.

The dose-response relationship between extracellular concentration of cytosine arabinoside (ara-C) and intracellular formation of the putative active metabolites of ara-C [ara-C incorporation into DNA and intracellular pools of ara-C in triphosphate form (ara-CTP)] was investigated in blast cells obtained from patients with acute nonlymphocytic leukemia (ANLL) by exposing these cells in vitro to 10, 100, or 1,000 nmol/L of ara-C. We studied 23 untreated patients who subsequently achieved complete remission (CR) with a regimen using daunorubicin and conventional doses of ara-C (ara-C-sensitive group), and 30 patients judged to be ara-C-resistant either by failing initial induction therapy (16 patients) or by having relapsed on an ara-C-containing maintenance regimen (14 patients). In both patient groups, ara-C incorporation into DNA and intracellular ara-CTP both displayed statistically significant increases in response to increasing extracellular concentrations of ara-C (P = .0001 in both cases), with the rate of increase of ara-CTP greater than that of ara-C incorporation. Moreover, blast cells from all patients, even those who were most clinically resistant to ara-C, were able to form ara-CTP and to incorporate ara-C into DNA. Each tenfold increment in extracellular ara-C concentration caused an 8.5-fold increase in ara-CTP, but only a 3.6-fold increase in ara-C incorporation into DNA. Thus, the efficiency of incorporation of ara-C into DNA (defined as the ratio of ara-C incorporation to ara-CTP pools) decreased by 58% with each tenfold increment in the extracellular concentration of ara-C (P less than .0001), presumably as a result of the inhibitory effect of ara-CTP on DNA polymerase. Using an analysis of covariance, modest differences were found in the levels of the ara-C metabolite variables in the ara-C-sensitive group as compared with the resistant group. However, because there was considerable overlap in ara-C metabolite formation among the patient groups, it was not possible to predict clinical outcome by these in vitro assessments of ara-C metabolism.

Acute Disease↗