Mitochondrial DNA deletions in coronary artery bypass grafting patients

OBJECTIVE

Mitochondrial DNA (mitoDNA) deletions have been shown to increase with aging and ischemia and have been suggested to contribute to myocardial dysfunction. The purpose of this study was to determine the prevalence and specificity of mitoDNA deletions in coronary artery bypass patients.

METHODS

Right atrial appendix tissue from 51 cardiac surgical patients (30-93 years; mean 64+/-14 years) was obtained during cardiopulmonary bypass cannulation (Control), just prior to the removal of the venous cannula (Ischemia, 169+/-38 min) and following removal of the cannula (Reperfusion) and used for polymerase chain reaction (PCR) and sequence analysis.

RESULTS

A novel mitoDNA deletion (approximately 7.3 kb, mitoDNA(7.3)) was found in three unrelated, male patients (53, 67, 75 years old). All mitoDNA(7.3) deletion breakpoints were found downstream of the ATP synthase 8 genes and at the 3' end of the cytochrome b genes. The prevalence of the mitoDNA(7.3) deletion was significantly increased (P<0.05) following ischemia and reperfusion. Clinical data indicated that postoperative left ventricular ejection fraction was lower (38.3 vs. 46.4%), and the incidence of previous myocardial infarction higher (1.7 vs. 0.6) in patients exhibiting mitoDNA deletions.

CONCLUSION

Our results reveal a novel mitochondrial DNA deletion occurring within the genome region coding for the mitochondrial genes of oxidative phosphorylation that is significantly increased during ischemia and reperfusion. The incidence and prevalence of mitoDNA(7.3) deletions in patients with clinical indications of poor recovery suggests that mitoDNA(7.3) deletions may provide an important indicator to surgical outcome in the cardiac surgical patient.

Lowest hematocrit on bypass and adverse outcomes associated with coronary artery bypass grafting. Northern New England Cardiovascular Disease Study Group

BACKGROUND

Cardiac surgery patients' hematocrits frequently fall to low levels during cardiopulmonary bypass.

METHODS

We investigated the association between nadir hematocrit and in-hospital mortality and other adverse outcomes in a consecutive series of 6,980 patients undergoing isolated coronary artery bypass graft surgery. The lowest hematocrit during cardiopulmonary bypass was recorded for each patient. Patients were divided into categories based on their lowest hematocrit. Women had a lower hematocrit during bypass than men but both sexes are represented in each category.

RESULTS

After adjustment for preoperative differences in patient and disease characteristics, the lowest hematocrit during cardiopulmonary bypass was significantly associated with increased risk of in-hospital mortality, intra- or postoperative placement of an intraaortic balloon pump and return to cardiopulmonary bypass after attempted separation. Smaller patients and those with a lower preoperative hematocrit are at higher risk of having a low hematocrit during cardiopulmonary bypass.

CONCLUSIONS

Female patients and patients with smaller body surface area may be more hemodiluted than larger patients. Minimizing intraoperative anemia may result in improved outcomes for this subgroup of patients.

Predicting the risk of death from heart failure after coronary artery bypass graft surgery

Heart failure is the most common cause of death among coronary artery bypass graft (CABG) patients. In addition, most variation in observed mortality rates for CABG surgery is explained by fatal heart failure. The purpose of this study was to develop a clinical risk assessment tool so that clinicians can rapidly and easily assess the risk of fatal heart failure while caring for individual patients. Using prospective data for 8,641 CABG patients, we used logistic regression analysis to predict the risk of fatal heart failure. In multivariate analysis, female sex, prior CABG surgery, ejection fraction <40%, urgent or emergency surgery, advanced age (70-79 yr and >80 yr), peripheral vascular disease, diabetes, dialysis-dependent renal failure and three-vessel coronary disease were significant predictors of fatal postoperative heart failure. A clinical risk assessment tool was developed from this logistic regression model, which had good discriminating characteristics (receiver operating characteristic clinical source = 0.75, 95% confidence interval: 0.71, 0.78).

IMPLICATIONS

In contrast to previous cardiac surgical scoring systems that predicted total mortality, we developed a clinical risk assessment tool that evaluates risk of fatal heart failure. This distinction is relevant for quality improvement initiatives, because most of the variation in CABG mortality rates is explained by postoperative heart failure.

Improved in-hospital mortality in women undergoing coronary artery bypass grafting. Northern New England Cardiovascular Disease Study Group

BACKGROUND

Few studies have examined the changes in in-hospital mortality for women over time. We describe the changing case mix and mortality for women undergoing coronary artery bypass grafting (CABG) from 1987 to 1997 in northern New England.

METHODS

Data were collected on 8,029 women and 21,139 men undergoing isolated CABG. The study consisted of three time periods (1987 to 1989, 1990 to 1992, and 1993 to 1997) to account for regional efforts to improve quality of care that occurred during 1990 to 1992.

RESULTS

Compared with 1987 to 1989, women undergoing CABG in 1993 to 1997 were older, had poorer ventricular function, and more often required urgent or emergency operations. The crude and adjusted mortality rates for both women and men decreased significantly over time. The absolute magnitude of the change in adjusted rates was greater for women (3.1%) than for men (1.5%). Although women represented only 28% of the study population, the decrease in their mortality accounted for 44% of the total decrease in adjusted mortality during the study period.

CONCLUSIONS

Over the last decade there has been a marked decrease in CABG mortality for women, despite a worsening case mix.

Use of the internal mammary artery graft and in-hospital mortality and other adverse outcomes associated with coronary artery bypass surgery

BACKGROUND

There is clear evidence that patients having coronary artery bypass graft surgeries with an internal mammary artery (IMA) have better long-term survival. Some studies have suggested a short-term protective effect as well but, because older and sicker patients are less likely to receive an IMA graft, there has been concern that the apparent protective effect of the IMA on short-term mortality has been confounded by other risk factors. This study was intended to examine the independent effect of IMA grafts on in-hospital mortality while adjusting for patient and disease factors.

METHODS AND RESULTS

We studied the use of the left IMA (LIMA) in 21 873 consecutive, isolated, first-time coronary artery bypass graft procedures from 1992 through 1999. A total of 87% of the patients received a LIMA graft. LIMA graft use was associated with a significantly decreased risk of mortality. The crude odds ratio for death (LIMA versus no LIMA) was 0.26 (95% confidence intervals, 0.22, 0.31; P:<0.001). LIMA grafts were protective across all major patient and disease subgroups. The odds ratios by subgroup ranged from 0.13 to 0.48. After adjustment for all major risk factors, the odds ratio for death was 0.40 (95% confidence intervals, 0.33, 0.48; P:<0.001). Rates of cerebrovascular accident, return to cardiopulmonary bypass, return to the operating room for bleeding, and mediastinitis or sternal dehiscence requiring surgery were also less in the LIMA group, although not significantly so.

CONCLUSIONS

These data suggest that in addition to its well-documented patency and long-term beneficial effect, LIMA grafting has a strong protective effect on perioperative mortality.

Risks of morbidity and mortality in dialysis patients undergoing coronary artery bypass surgery. Northern New England Cardiovascular Disease Study Group

BACKGROUND

Although dialysis patients are undergoing CABG with increasing frequency, large studies specifically comparing patient characteristics and procedure-related risks in this population have not been performed.

METHODS AND RESULTS

We conducted a regional prospective cohort study of 15,500 consecutive patients undergoing CABG in northern New England from 1992 to 1997. We used multiple logistic regression analysis to examine associations between preoperative dialysis-dependent renal failure and postoperative events and to adjust for potentially confounding variables. The 279 dialysis-dependent renal failure patients (1.8%) were 4.4 times more likely to experience in-hospital mortality than were other CABG patients (12.2% versus 3.0%, respectively; P:<0.001). Dialysis-dependent renal failure patients were older and had more comorbidities and more severe cardiac disease than did other CABG patients. After adjusting for these factors in multivariate analysis, however, dialysis-dependent renal failure patients remained 3.1 times more likely to die after CABG (adjusted odds ratio [OR] 3.1, 95% CI 2.1 to 4.7; P:<0.001). Dialysis-dependent renal failure patients compared with other CABG patients also had a substantially increased risk of postoperative mediastinitis (3.6% versus 1.2%, respectively; adjusted OR 2.4, 95% CI 1.2 to 4.7; P:=0.011) and postoperative stroke (4.3% versus 1.7%, respectively; adjusted OR 2. 1, 95% CI 1.1 to 3.9; P:=0.016), even after controlling for potentially confounding variables. Risks of reexploration for bleeding were similar for patients with and without dialysis-dependent renal failure.

CONCLUSIONS

Preoperative dialysis-dependent renal failure is a strong independent risk factor for in-hospital mortality and mediastinitis after CABG.

Mediastinitis and long-term survival after coronary artery bypass graft surgery

BACKGROUND

Mediastinitis is a dreaded complication of coronary artery bypass surgery (CABG). The long-term effect of mediastinitis on mortality after CABG has not been well studied.

METHODS

We examined the survival of 15,406 consecutive patients undergoing isolated CABG surgery from 1992 through 1996. Patient records were linked to the National Death Index. Mediastinitis was defined as occurring during the index admission and requiring reoperation.

RESULTS

Mediastinitis occurred in 193 patients (1.25%). Patients with mediastinitis were older and more likely to have had emergency surgery, diabetes, peripheral vascular disease, chronic obstructive pulmonary disease, and preoperative dialysis-dependent renal failure. Patients with mediastinitis were also more likely to be severely obese and had somewhat lower preoperative ejection fraction. After multivariate adjustment for these factors, the first year post-CABG survival rate was 78% with mediastinitis and 95% without, and the hazard ratio for mortality during the entire follow-up period was 3.09 (CI 95% 2.28, 4.19; p < 0.0001).

CONCLUSIONS

Mediastinitis is associated with a marked increase in mortality during the first year post-CABG and a threefold increase during a 4-year follow-up period.

Decreasing mortality for aortic and mitral valve surgery in Northern New England. Northern New England Cardiovascular Disease Study Group

BACKGROUND

Although numerous reports have documented declining mortality rates associated with coronary artery bypass surgery in recent years, it is unknown whether similar trends have occurred with valve surgery during this time.

METHODS

We conducted a regional, prospective study to assess trends in patient casemix and in-hospital mortality rates over time with aortic valve replacement (AVR), mitral valve replacement (MVR), and mitral valve repair. Data were collected from all patients undergoing AVR (n = 2,596), MVR (n = 759), or mitral valve repair (n = 522) in Northern New England between January 1992 and December 1997. Logistic regression was used to identify significant predictors of in-hospital mortality and to calculate risk-adjusted mortality rates.

RESULTS

For AVR, the trend in patient casemix was toward increased risk with increases in patient age and in the proportion of patients with: body surface area less than 1.7, diabetes, coronary artery disease, and prior valve surgery. A decrease was noted in the proportion of patients undergoing additional surgical procedures. For MVR, patient risk improved over the time period with fewer female patients and fewer patients with coronary artery disease. For mitral valve repair patient risk increased over the time period with increases in the proportion of patients with coronary artery disease, diabetes, and whose surgical priority was classified as urgent. In addition, there was a borderline significant increase in the proportion of mitral valve repair patients in New York Heart Association class IV preoperatively. Risk-adjusted mortality decreased 44% from 9.3% in 1992 through 1993 to 5.3% in 1996 through 1997 for patients undergoing AVR (p = 0.01) and decreased 53% from 13.6% in 1992 through 1993 to 8.2% in 1996 through 1997 for patients undergoing MVR (p = 0.01). We observed a statistically insignificant increase in risk-adjusted mortality over the time period for patients undergoing mitral valve repair (from 3.6% in 1992 through 1993 to 5.0% in 1996 through 1997; p = 0.34).

CONCLUSIONS

Significant improvement in mortality rates with valve replacement was observed in northern New England during this time period. This improvement persisted following adjustment for changes in patient casemix over this time. These trends mirror improvements in mortality with other cardiac surgical interventions that have been observed in recent years in our region and nationally.

Predictors of 30-day hospital readmission after coronary artery bypass

BACKGROUND

Risk factors for 30-day hospital readmission following coronary artery bypass grafting (CABG) have not been established.

METHODS

We prospectively followed 485 consecutive patients who underwent isolated primary CABG at our institution in 1997. Patients were contacted by telephone at 30 days following operation to determine readmission status.

RESULTS

The overall readmission rate was 16% (76 of 485). Female gender (25% versus 11%, p = 0.001) and diabetes (22% versus 12%, p = 0.005) were associated with significantly higher readmission rates. The relationship between female gender and readmission persisted after correcting for age and other comorbidities. Congestive heart failure trended towards a significant relationship with increased readmission rate (22% versus 14%, p = 0.09). There were no significant associations between 30-day readmission rate and age, hypertension, chronic obstructive pulmonary disease, history of myocardial infarction, peripheral vascular disease, creatinine level of > or = 1.4 mg/dL, or decreased left ventricular ejection fraction (< 40%).

CONCLUSIONS

These data show that most of the classic risk factors for postoperative mortality are not necessarily associated with increased readmission. However, female gender and diabetes are associated with greater than twice the risk of 30-day readmission following CABG.

Trends in rates of reexploration for hemorrhage after coronary artery bypass surgery. Northern New England Cardiovascular Disease Study Group

BACKGROUND

While mortality rates associated with coronary artery bypass grafting (CABG) have been declining, it is unknown whether similar improvements in the rates of morbidity have been occurring. This study examines trends in reexploration rates for hemorrhage, one of the serious complications of CABG surgery. It also explores changes in patient characteristics and several surgeon practice patterns potentially related to bleeding risks that may explain variations in these rates.

METHODS

We performed a regional observational study of all of the 12,555 consecutive patients undergoing isolated CABG surgery in northern New England between 1992 and 1997. The rates of reexploration and patient characteristics were examined between two time intervals: period I (January 1, 1992 to June 1, 1994) and period II (June 1, 1995 to March 31, 1997). All of the region's 23 practicing surgeons responsible for these patients were surveyed to assess changes in practice patterns potentially related to bleeding risks.

RESULTS

The adjusted rates of reexploration for bleeding declined 46% between periods I and II (3.6% versus 2.0%, p < 0.001). All of the five cardiac centers in northern New England showed similar trends with adjusted risk reductions ranging from 32% to 48% between the two time periods. This decline occurred despite the patients in period II having higher percentages of risk factors for reexploration for bleeding compared to patients in period I. From the surgeon survey, the number of surgeons using antifibrinolytics markedly increased from period I to period II. More surgeons were also using preoperative aspirin and heparin up until the time of surgery in period II.

CONCLUSIONS

Similar to the rates of mortality, the rates of reexploration for bleeding following CABG surgery are substantially declining. This decrease in the reexploration rates occurred despite higher patient risks.

Gender and functional outcome after coronary artery bypass

BACKGROUND

Female gender is an established risk factor for increased mortality and morbidity after coronary artery bypass graft (CABG) surgery. However, the impact of gender on functional outcome after CABG is not well established.

METHODS

Functional status was assessed at baseline and at 6 months with the Duke Activity Status Index (DASI) in 196 consecutive patients undergoing isolated primary CABG. Follow-up data were complete in 158 (81%) patients. The functional status of the 54 (34%) female and the 104 (66%) male patients was compared.

RESULTS

The mean DASI score was significantly lower in women at baseline (19.3 +/- 13.8 vs 28.3 +/- 16.8, P = .001) and at 6 months (22.7 +/- 16.3 vs 32.8 +/- 18.2, P = .0007); however, the 6-month change in DASI score (3.3 +/- 16.9 vs 4.5 +/- 20.0, P = .7) was comparable. A similar proportion of women and men (54% vs 53%) had improved above their baseline functional level at 6 months.

CONCLUSIONS

These data demonstrate that women undergo CABG at a significantly lower functional level than men; however, the functional improvement after CABG is similar across genders.

Hospital readmission after cardiac surgery. Does "fast track" cardiac surgery result in cost saving or cost shifting?

BACKGROUND

Intense medical and economic pressures have created "fast track" cardiac surgery in which clinical services are streamlined and early discharge is encouraged. Does this strategy promote significant cost saving or merely cost shifting? In a global system of reimbursement, the economic benefit of decreasing patient length of stay may be offset by high rates of patient readmission. This study was undertaken to determine the 30-day readmission rate after cardiac surgery and to analyze trends of readmission diagnoses.

METHODS AND RESULTS

From October 1, 1996 to July 31, 1997, 460 consecutive cardiac surgical operations were performed at 1 institution. There were 25 deaths and 8 patients who remained as inpatients at the 30-day postoperative deadline for readmission. Two patients had 2 operations. Therefore, 527 operations were performed on 525 patients. There were 110 readmissions after 527 operations for a readmission rate of 20.9%. A significant number of readmissions (49%) were to outside hospitals. Readmission diagnoses were: atrial fibrillation (23%); angina, congestive heart failure, or ventricular tachycardia (20%); leg wound (15%); sternal wound (5%); pneumonia (5%); gastrointestinal complaints (5%); neurologic event (2%); and miscellaneous (25%). Patients discharged > or = 7 days postoperatively were twice as likely to be readmitted as those discharged on postoperative days 4, 5, or 6.

CONCLUSIONS

Readmission after cardiac surgery is common and frequently (49%) to outside institutions. Patients discharged > or = 7 days postoperatively represent the patients at greatest risk of readmission and, therefore, warrant closer scrutiny before discharge.

Central venous catheter use in low-risk coronary artery bypass grafting

BACKGROUND

To assess the impact of central venous pressure catheter monitoring in low-risk coronary artery bypass grafting (CABG), we compared the hospital course of patients undergoing CABG with central venous pressure catheter monitoring with that of similar patients undergoing CABG with pulmonary artery catheter monitoring.

METHODS

All isolated primary CABG procedures (n = 312) performed between April 22 and October 31, 1996, were evaluated, and 194 patients meeting six central venous pressure catheter use criteria were identified. Of these 194 patients, 133 (68%) underwent CABG with central venous pressure catheter monitoring, and 61 (32%) had pulmonary artery catheter monitoring owing to surgeon or anesthesiologist preference.

RESULTS

In-hospital mortality was similar. A trend toward increased overall complications was seen in the pulmonary artery catheter group. The total volume infused in the first 12 hours, the 24-hour weight gain, and the intubation time were significantly greater in the pulmonary artery catheter group. Increases in intensive care unit length of stay and in total hospital charges trended toward statistical significance in the pulmonary artery catheter group.

CONCLUSIONS

Pulmonary artery catheter use in low-risk patients undergoing CABG was associated with greater weight gain and longer intubation time and may be associated with increased morbidity and utilization of hospital resources.

Clinical and economic impact of diabetes following coronary artery bypass

BACKGROUND

Diabetes has been shown to have a negative impact on mortality following coronary artery bypass graft (CABG) surgery. This analysis examines the impact of diabetes on additional clinical and economic outcomes.

MATERIAL AND METHODS

Between May and October of 1996, 312 consecutive patients undergoing isolated primary CABG were followed through hospital discharge. A total of 114 diabetics (37%) and 198 nondiabetics (63%) was evaluated. Among the diabetics, 62 (54%) were insulin requiring and 52 (46%) were treated with oral hypoglycemic agents or with diet alone.

RESULTS

The incidences of major clinical complications including death, renal failure, stroke, reexploration for bleeding, and mediastinitis or sternal dehiscence were not significantly different among insulin-requiring diabetics, noninsulin-requiring diabetics, and nondiabetics. However, insulin-requiring diabetics had a significantly longer (P < 0.01) total length of stay compared to both noninsulin-requiring diabetics and nondiabetics (107 +/- 12.7 days vs. 5.6 +/- 1.5 days vs. 6.8 +/- 5.4 days, respectively), a significantly longer (P < 0.01) intensive care unit length of stay (5.3 +/- 12.4 days vs. 1.4 +/- 0.8 days vs. 2.0 +/- 3.9 days, respectively), and significantly greater (P, 0.01) total hospital charges (48.7 +/- 56.1 thousand dollars vs. 29.3 +/- 4.3 thousand dollar vs. 32.9 +/- 18.9 thousand dollars, respectively). There were no significant differences between the noninsulin-requiring diabetics and the nondiabetics with regard to these clinical and economic outcomes.

CONCLUSIONS

Diabetics treated with oral hypoglycemic agents or with diet alone have clinical and economic outcomes similar to nondiabetics following CABG. Insulin-requiring diabetes, however, predicts significantly increased hospital resource utilization. Future outcome assessment and resource utilization analyses must stratify diabetes by treatment to be completely accurate.

Reexploration for hemorrhage following coronary artery bypass grafting: incidence and risk factors. Northern New England Cardiovascular Disease Study Group

OBJECTIVE

To assess mortality and risk factors associated with reexploration for hemorrhage in patients undergoing coronary artery bypass grafting (CABG).

DESIGN

Regional cohort study. Patient characteristics, treatment variables, and outcome measures were collected prospectively.

SETTING

All 5 centers performing cardiac surgery in Maine, New Hampshire, and Vermont.

PATIENTS

A consecutive cohort of 8586 patients undergoing isolated CABG between 1992 and 1995.

MAIN OUTCOME MEASURES

Postoperative hemorrhage leading to reexploration, in-hospital mortality, and length of stay.

RESULTS

A total of 305 patients (3.6%) underwent reexploration for bleeding. In these patients, in-hospital mortality was nearly 3 times higher (9.5% vs 3.3% for patients not requiring reoperation, P<.001) and average length of stay from surgery to discharge was significantly longer (14.5 days vs 8.6 days, P<.001). High rates of reexploration for hemorrhage were observed in patients with prolonged (> 150 minutes) cardiopulmonary bypass (39 [11.1%] of 351) and in those requiring an intra-aortic balloon pump intraoperatively (12 [8%] of 139). In multivariate analysis, older age, smaller body surface area, prolonged cardiopulmonary bypass, and number of distal anastomoses were associated with increased bleeding risks. The use of thrombolytic therapy within 48 hours of surgery was weakly but not significantly associated with the need for reexploration. Factors not significantly associated with reexploration included patient sex, preoperative ejection fraction, surgical priority, history of liver disease, myocardial infarction, prior CABG, renal failure, and diabetes mellitus.

CONCLUSIONS

Hemorrhage requiring reexploration after CABG is associated with markedly increased mortality and length of stay. Patients predicted to have increased risks of bleeding may benefit from prophylactic use of aprotinin, aminocaproic acid, or other agents shown to reduce hemorrhage.

Successful surgical management of an aortic arch aneurysm with acute aorto-pulmonary fistula

Aortic arch aneurysm with acute aorto-pulmonary fistula is usually a postmortem diagnosis. Few reports of successful surgical management are noted. Despite the many advances in cardiac surgery over the last 30 years, the observed mortality rate for surgical correction has been very high. Early diagnosis and prompt surgical intervention using profound hypothermia and total circulatory arrest are essential to successful outcome.

Preoperative risk factors that predict hospital length of stay in coronary artery bypass patients > 60 years old

BACKGROUND

The ability to predict prolonged length of stay (LOS) is essential to control escalating hospital costs. Operative mortality is a poor predictor of LOS; morbidity as defined by hospitalization for > 14 days after coronary artery bypass graft surgery (CABG), appears to be responsible for increasing costs. The purpose of this study was to measure preoperative predictive indicators of increased LOS with an eventual plan to offer alternative cost-benefit therapeutic options.

METHODS AND RESULTS

Nine hundred twenty-four consecutive patients (age, 60-86 years) undergoing CABG were retrospectively studied by means of the Cox proportional hazards model. Seventeen variables, excluding death, were analyzed and quantified as to importance, and point totals were calculated for each patient. Scores were 12 for congestive heart failure and intra-aortic balloon assist device; 10, creatinine > 2; 6, intra-aortic balloon assist device only; 5, congestive heart failure only; 3, obesity; 6, age > 75 years; 3, age 70-75 years; and 2, 65-69 years.

CONCLUSIONS

Increasing index score directly correlated with an exponential increase in LOS. These data substantiate the hypothesis that a mathematical model can predict LOS in CABG patients and may offer rational alternative strategies in delivering cost-effective health care.

Review of coronary-subclavian steal following internal mammary artery-coronary artery bypass surgery

The syndrome of coronary-subclavian steal through an internal mammary artery graft following coronary artery bypass grafting is rare. We are aware of only eight cases reported in the world literature. The cases of these 8 patients are reviewed, and the case of the ninth patient is described. All patients but 1 have been successfully managed by subclavian-carotid artery bypass.

Effects of specific active immunization on tumor recurrence following primary tumor resection in WF rats with 1,2-dimethylhydrazine-induced bowel cancer

Primary gastrointestinal tumors were induced in male WF rats by 16 weekly sc injections of 1,2-dimethylhydrazine [(DMH) CAS: 540-73-8; 20 mg/kg/wk]. Twenty-four to 28 weeks after the start of DMH injections, all rats were surgically explored and gastrointestinal tumors were resected. Rats with no remaining microscopic disease after operation were immunized with one of four tumor isografts. The first isograft, DMH-W163, is a poorly differentiated mucinous adenocarcinoma explanted from a colon cancer in a DMH-treated animal. It has been shown to possess antigens that cross-react with other DMH-induced bowel adenocarcinoma isografts. The second isograft, DMH-W49, is a carcinosarcoma explanted from a DMH-treated primary colon cancer. It has intermediate antigenic cross-reactivity with other colon adenocarcinoma isografts in the WF model. The third isograft, DMH-W15, is a sarcoma explanted from a DMH-induced colon cancer that does not possess antigens cross-reactive with other DMH-induced colon adenocarcinomas. The fourth isograft, SPK, is a spontaneous (non-DMH-induced) renal cell carcinoma that is immunogenic but should not contain tissue-type-specific antigens cross-reacting with the bowel cancers. Immunized rats received three sc weekly injections of 1 X 10(3) irradiated cells. Concomitant control rats received no immunization after resection of the primary tumor. Within 24 weeks of primary tumor resection, 12 of 16 (75%) rats not immunized had tumor recurrence. Only 8 of 24 (34%) rats immunized with DMH-W163 had tumor recurrence (P less than .025 compared to controls). Fifty percent of animals (10/20) immunized with the carcinosarcoma DMH-W49 had a recurrence. Animals immunized with the non-cross-reacting DMH-W15 sarcoma isograft had a recurrence rate similar to that of controls (16/20, 75%). The rats immunized with SPK were not protected from recurrence. Twelve of 19 (63%) had a recurrence at or near the suture line within 24 weeks following primary tumor resection. These results confirm that adjuvant immunotherapy can decrease the rate of recurrence following primary tumor resection in this model. In addition, immunogens that possessed tissue-type-specific antigens were more effective in preventing tumor recurrence than those that did not.

The effect of 1,2-dimethylhydrazine (DMH) carcinogenesis on peripheral T cell subsets in the Wistar Furth rat

1,2-dimethylhydrazine (DMH)-induced colon cancer in Wistar/Furth (W/Fu) rats is analogous in many ways to human colorectal cancer. As part of our attempt to understand the immunobiology of these tumors, we have utilized the recently available monoclonal antibodies W3/25 and OX8 to monitor helper (Th) and suppressor (Ts) lymphocyte subpopulations. Normal untreated male W/Fu rats of less than 1 year of age were phenotyped (n = 43). The mean percentage of Th and Ts was 42 +/- 1 (mean +/- SEM) and 33 +/- 1, respectively. The mean Th/Ts ratio was 1.3 +/- 0.1. A Th/Ts equal to or greater than 1 is considered "normal" in the W/Fu rat. The DMH-treated rats (20 mg/kg/wk) were evaluated in initial experiments at various intervals after treatment. Rats studied 24 hours after a single DMH injection had no alterations in T cell subsets. Rats studied 28, 32, and 65 weeks after the start of 16 weekly DMH injections were found to have a decrease in the percentage of Th and a relative increase in Ts, with Th/Ts ratios of 0.6 +/- 0.2, 0.7 +/- 0.1, and 0.7 +/- 0.1, respectively (each P less than 0.01). In a separate experiment in which rats were studied after 4, 8, and 16 weeks of DMH injections, no alterations in T cell subsets were noted. Rats (n = 5) studied at 20 weeks after the start of DMH were found to have 41 +/- 3% Th and 36 +/- 2% Ts and a Th/Ts ratio of 1.2 +/- 0.1. Three of five rats were found to have adenocarcinomas. Four of five rats had Th/Ts less than 1. One rat with Th/Ts equal to 0.9 had metastatic disease. Rats studied at 25 weeks (n = 8) were found to have more advanced carcinomas (4/8) that were causing obstruction or bleeding in the animal. There was a significant decrease in Th and Ts in this group, with 24 +/- 3% and 26 +/- 3% respectively (P less than 0.001). The Th/Ts ratio for this group was 0.9 +/- 0.1 (P less than 0.01). In other experiments, rats were treated with DMH or placebo over a 16-week period and serially bled during and after treatment. No effect of DMH treatment on T cell subsets was noted. Repeated bleeding alone was noted to cause persistent alterations of T cell subpopulation.(ABSTRACT TRUNCATED AT 400 WORDS)

Identification of material with paternal HLA antigen immunoreactivity from purported circulating immune complexes in patients with gestational trophoblastic neoplasia

Circulating immune complex(es) (CIC) have been shown to rise progressively only when patients with hydatidiform molar pregnancy enter gonadotropin-documented remission. The CIC in 3 patients with gestational trophoblastic neoplasia (GTN)--1 with hydatidiform mole and 2 with choriocarcinoma--were characterized. Their clinical course was monitored by serial antigen-nonspecific polyethylene glycol (PEG) 6000-CIC assay and simultaneous human chorionic gonadotropin (HCG) assay from presentation until sustained gonadotropin-documented remission. As serial HCG progressively decreased to normal following surgical or chemotherapeutic reduction in tumor burden, PEG-CIC concurrently rose. Serum obtained at or near peak PEG-CIC levels was precipitated by 3.75% PEG 6000 and fractionated by column chromatography on Sephadex G-200 (exclusion limit, greater than 600,000 mol wt) in glycine-HCl and 1 M NaCl buffer at pH 2.8. None of the 5 elution fractions obtained from the 3 patients contained HCG or anti-HCG activity. However, in the hydatidiform molar patient, fractions 1 through 3 (mol wt greater than 67,000--and containing immunoglobulin) were shown to competitively inhibit complement-dependent antibody lysis on 1 of 4 paternal HLA haplotype (AW32) targets. In 2 of the 3 patients studied, low-molecular-weight fractions (not containing immunoglobulin) significantly inhibited reference anti-HLA binding of antisera directed against only 1 of 4 paternal HLA haplotypes. The immunospecificity of this inhibition was confirmed by criss-cross control assays in which elution fractions obtained from both of these patients were tested for inhibition of lymphocytolysis of both sets of paternal lymphocytes. None of these fractions were immunoreactive to maternal HLA haplotypes. Further analysis of serum from the hydatidiform molar patient revealed that no free complement-fixing antibody against paternal antigens could be found by conventional screening assays in unfractionated patient sera. Three of 4 paternal HLA antigens or non-complement-fixing anti-HLA immunoglobulin was detected in unfractionated pretreatment, treatment, and remission sera of the hydatidiform molar patient. Only in this patient's remission sera was unbound AW32 antigen or non-complement-fixing anti-AW32 antibody detected. These data demonstrate the successful characterization of at least 1 specific antigen fractionated from a tumor-associated immune complex. The implication that some patients with GTN may recognize and react to immunogenic paternal HLA antigens as part of their successful response to therapy for trophoblastic tumor is discussed.

Characterization of antigenic components from circulating immune complexes in patients with gestational trophoblastic neoplasia

The authors have studied serial circulating immune complex (CIC) levels in 15 patients with gestational trophoblastic neoplasia (GTN) for several reasons. Gestational trophoblastic neoplasia can easily be followed from presentation to remission, and CIC changes can be compared with changes in human chorionic gonadotropin (HCG) which is a specific and quantitative marker of trophoblastic tumor load. Twelve patients with hydatidiform molar pregnancy presented with normal CIC levels (255 delta OD450 +/- 97, mean SE [standard error]) as measured by our antigen nonspecific polyethylene glycol (PEG) turbidity assay. Only after reduction in tumor load as monitored by a fall in HCG did CIC rise. In contrast, three patients with choriocarcinoma presented with significantly elevated CIC levels (513 delta OD450 +/- 147, P less than 0.05 compared to normals) which slowly declined in parallel with HCG levels following evacuation and chemotherapy. Sera at peak PEG-CIC from three patients with molar pregnancy or choriocarcinoma were precipitated with 3.75% polyethylene glycol to concentrate circulating immune complexes. Circulating immune complex levels were fractionated on Sephadex G-200 in an acid buffer (pH = 2.8). An identifiable antigenic component of the CIC in both diseases was found to be paternal HLA antigen. This was demonstrated by the ability of the latest eluting CIC fraction to inhibit paternal lymphocyte lysis using anti-HLA antisera against the husband's HLA tissue type. In each case, this fraction contained no immunoglobulin or beta-2 microglobulin and was antigenically crossreactive with only one of the husband's HLA haplotypes. The authors believe the PEG-CIC assay has allowed them to define the kinetics of host humoral response in GTN, and has provided a method for recovering immunogenic tumor-associated antigens from these complexes which may apply to other solid tumors.

Gut-associated lymphoid tissue and dimethylhydrazine-induced colorectal carcinoma in the Wistar/Furth rat

Although gut-associated lymphoid tissue in the form of discrete lymphoid patches (LP-GALT) in mammalian intestine in most prominent in the distal ileum, appendix, and, in some species, the cecal appendage, LP-GALT can be found throughout the intestinal tract. LP-GALT appears as single or multiple subepithelial lymphoid follicles covered by a specialized, structurally unique epithelium. In the colon of the Wistar/Furth (W/Fu) rat, LP-GALT appears as aggregates of follicles, or lymphoid patches, that can be detected macroscopically. We studied the relationship between 1,2-dimethylhydrazine- (DMH) induced colon carcinomas and the lymphoid patch associated epithelium in these animals. In addition, we defined the normal distribution of colonic lymphoid patches in both DMH-treated and control rats. Patches were found macroscopically and confirmed by histologic examination at five constant sites: lower pole of cecum, proximal ascending colon, the major colonic flexure, mid descending colon, and the rectosigmoid. There are also the predominant sites of DMH induced carcinomas in W/Fu rats. In 120 DMH-treated animals, 109 colon carcinomas were found. Eight percent were in the lower pole of the cecum, 56% in the proximal ascending colon, 16% at the major flexure, 15% in the mid descending colon, and 5% in the rectosigmoid. Lymphoid patches could often be detected histologically in association with DMH-induced tumors. The depth of tumor invasion was found to correlate inversely with our ability to identify tumor-associated lymphoid patches suggesting that tumors arising at the anatomical sites were lymphoid patches occur progressively destroyed them. Of colon tumors confirmed histologically to be associated with lymphoid patches, 88% were superficial lesions confined to the submucosa and 12% were more extensive but confined to the bowel wall. No lymphoid patches could be found associated with tumors that extended through the bowel wall. Thus, DMH-induced colon carcinomas in W/Fu rats arise at sites containing preexisting LP-GALT with associated specialized epithelium.

Serial circulating immune complex levels and mitogen responses during progressive tumor growth in WF rats

Inbred male WF rats were given im injections of one of two antigenically and histologically distinct syngeneic tumor isografts, adenocarcinoma DMH-W 163 or spontaneous renal cell carcinoma SPK. Serum and peripheral blood lymphocytes were harvested from tumor-bearing and normal age-matched controls before and after isograft challenge at weekly intervals. Serial circulating immune complex (CIC) levels were quantitated by polyethylene glycol (PEG) insolubilization. T-cell mitogen responses to phytohemagglutinin (PHA) and concanavalin A (Con A) were followed serially. Tumor growth was measured at least weekly. PEG-CIC values rose early after tumor injection, increased with tumor growth, and declined in some animals just before death. Mitogen response to PHA was significantly decreased in isografted tumor-bearing rats, particularly at later stages of tumor development, compared to normal uninoculated controls. Responses to Con A were variable, and suppression was not always seen in tumor bearers. In animals that did not have progressive tumor growth after isograft injection, PEG-CIC levels did not change and responses to PHA were not suppressed. Patterns of CIC change and responses to PHA were not affected by differences in tumor histology or growth rates. Thus serial CIC levels measured by the PEG assay correlate with tumor growth and precede nonspecific suppression of T-cell mitogenic response in these animal tumor models.

Circulating immune complex levels in patients with molar pregnancy

Circulating immune complex levels were measured in patients with molar pregnancy to investigate the relationship between circulating immune complex and trophoblastic tumor burden. When 27 (87%) of 31 patients with molar pregnancy were first seen, circulating immune complex values were in the normal range. Three of the 4 patients with elevated levels had concurrent medical illness. Eighteen patients were followed with serial measurements until gonadotropin remission was achieved and all 18 patients developed increased levels as they entered remission (P less than .001). Circulating immune complex values remained elevated during gonadotropin remission from 6 to 16 weeks and then declined to initial levels. Further investigation should be undertaken to evaluate possible interactions between circulating immune complex and host immune defenses.

Management of combined segment disease

Eighty-five of 148 inflow procedures were performed for combined segment disease. Our study shows that aortofemoral bypass is clinically and functionally superior to axillofemoral bypass in limbs with combined segment disease and hemodynamic criteria for limb salvage. The results of these two procedures are comparable for claudicant limbs. A derivative of segmental plethysmography, the predictive index, can select preoperatively those limbs that will fail to respond to aortofemoral bypass alone. Finally, either in limbs selected for aortofemoral bypass with both ischemic tissue lesions and a predictive index greater than 0.2 or in limbs selected for axillofemoral bypass with ischemic tissue lesions alone, a synchronous procedure can be performed with relatively low morbidity and excellent early functional results.

A comparison of the early noninvasive hemodynamic results after aortofemoral or axillofemoral bypass graft

Aortofemoral (AF) and axillofemoral bypass grafts (AXFG) are alleged to have similar patency rates, but little is known of their comparative functional results. In 91 limbs clinically selected for AXFG or AF, pulse volume recording amplitude (PVR) and Dopper systolic ankle/brachial artery pressure ratio (DSP A/B) were measured before and 6 months after surgery. Preoperatively, the limbs were classified by angiography into aortoiliac disease alone (AI) or AI and femoropopliteal disease (AIFP), and were further classified by PVR and DSP A/B into claudication and limb salvage groups. Six months after surgery, the degree of hemodynamic improvement was comparable for AF and AXFG for limbs with AI. After AXFG in AIFP, however, the claudication group showed less of an improvement in DSP A/B ratio and PVR than with AF. There was no functional improvement after AXFG in the limb salvage group. AF appears to be associated with better functional results than AXFG in AIFP.

A prospective study of Doppler pressures and segmental plethysmography before and following aortofemoral bypass. Implications for predicting success and for adopting a uniform method of classifying arterial disease

To determine the clinical and hemodynamic changes associated with aortofemoral bypass, 44 limbs of 31 patients underwent segmental plethysmography (PVR) and Doppler pressures (DSP) before operation, immediately after operation, and again at 6 months. Prior to operation patients were separated by angiographic criteria into two groups: aortoiliac segment disease alone (AI) (n = 22), and aortoiliac and femoropopliteal segment disease (AIFP) (n = 22). At 6 months the two groups were subdivided into four groups based on relief (oSx) or lack of relief (+Sx) of symptoms. Before operation the only significant difference between the four groups was a higher thigh PVR and calf DSP in the AI + Sx group. Six month PVR values in AIoSx were improved nearly twofold over preoperative measurements at the thigh and calf, but at the thigh level only for AIFPxSx. DSP was increased at all three levels in both AI and AIFPoSx groups. No hemodynamic improvement occurred in either the AI or the AIFP + Sx groups. A derivative index of PVR (thigh-ankle/15 mm) or the FPomega was significantly lower in AIFOsSx before operation. There was a significant disparity between classification by hemodynamics and by symptoms prior to operation which lessened somewhat after operation. These studies suggest that success or failure can be predicted before operation in AIFP by FPomega, and arterial disease should be classified by a combination of symptoms, angiography, and hemodynamics.