Use of FT-NIR transmission spectroscopy for the quantitative analysis of an active ingredient in a translucent pharmaceutical topical gel formulation

The objective of this study was to demonstrate the use of transmission Fourier transform near-infrared (FT-NIR) spectroscopy for quantitative analysis of an active ingredient in a translucent gel formulation. Gels were prepared using Carbopol 980 with 0%, 1%, 2%, 4%, 6%, and 8% ketoprofen and analyzed with an FT-NIR spectrophotometer operated in the transmission mode. The correlation coefficient of the calibration was 0.9996, and the root mean squared error of calibration was 0.0775%. The percent relative standard deviation for multiple measurements was 0.10%. The results prove that FT-NIR can be a good alternative to other, more time-consuming means of analysis for these types of formulations.

Differential response to targeted recruitment strategies to fitness promotion research by African-American women of varying body mass index

OBJECTIVE

To assess patterns of recruitment into a community-based NCI-funded physical activity and dietary lifestyle change program targeting African-American women.

DESIGN

Acquisition of a convenience sample to be screened for participation in a randomized, controlled prevention intervention.

SETTING

African-American-owned and -operated health club located in an area of Los Angeles in which African Americans are concentrated.

PARTICIPANTS

893 African-American women. RECRUITMENT STRATEGIES: Social networking/word-of-mouth, staff presentations, mass and targeted media, and physician referral.

MAIN OUTCOME MEASURE

Completion of screening questionnaire indicating a desire to enroll in the study. Screening questionnaire domains included self-reported height and weight, recent participation in organized weight loss programs, ability to walk one mile unassisted, current medication use, smoking status, personal medical history of cancer, sociodemographic variables, and recruitment source.

RESULTS

Sociodemographic and anthropometric characteristics distinguished between respondents obtained through different recruitment strategies. In particular, women with a higher body mass index (BMI) were more likely than those with lower BMIs (P = .014) to be recruited through more personalized methods (eg, social networking).

CONCLUSIONS

Culturally tailored recruitment strategies are critical in securing the participation of members of "hard-to-reach" populations, who are both under-represented in health promotion research and at high risk for chronic diseases.

Psychosocial versus nicotine-only self-report measures for predicting follow-up smoking status

The most popular measure of tobacco dependence, the Fagerstrom Tolerance Questionnaire (FTQ), measures only tobacco-specific behaviors. In contrast, the most popular assessment of addiction among polydrug users is the Addiction Severity Index (ASI). Most of the subscales comprising the ASI are psychosocial measures, not drug-specific measures. A study was undertaken to compare the predictive utility of these two contrasting measures. The NAS (adapted from the FTQ) and the Addiction Severity Index (ASI) were used to predict future smoking status in a cohort of polydrug users followed annually for 3 years. The baseline NAS score explained more of the variance in Time 2 and Time 3 smoking status than did the ASI subscales. When previous smoking status was included as a covariate, however, the NAS no longer predicted future smoking status, whereas the ASI Subscales continued to explain significant variance in future smoking status. Results suggest that when past smoking behavior is known, a respondent's legal status and alcohol use may be more useful than a measure of tobacco dependence for predicting future smoking status.

Individual change amid stable smoking patterns in polydrug users over 3 years

The pattern of stability/change in smoking status was examined annually in 254 community-dwelling polydrug users over 3 years. Respondents' smoking status was classified as nonsmoker, intermittent smoker, or "everyday" smoker. Results showed that the typical probability of retaining the same smoking status across any two consecutive assessments was: 0.77 for nonsmokers (never smokers and former smokers combined), 0.82 for everyday smokers, and 0.16 for intermittent smokers. The transition matrix proved stable across three observations; the predicted equilibrium distribution matched well with observed distributions. Fifty-five percent of intermittent smokers converted to everyday smoking within a year, but 29% converted to former-smoker status in the same period. No other transition exceeded 12%. Considerable flux in individual smoking status, particularly among intermittent smokers, was observed despite stable prevalence of smoking status in this population. Intermittent smoking status appeared to be a temporary "way station" between the two more stable everyday smoker and nonsmoker classifications. Results challenge current assumptions about "occasional" or "chipper" smokers.

Overweight and depressive symptoms among African-American women

BACKGROUND

In a national survey, a correlation between overweight and depression was explained by dieting and poor health. This study examines overweight and depressive symptoms among urban African-American women, taking into account demographic factors, health status and practices, and psychosocial constructs.

METHODS

Respondents are 429 participants in a pilot for a culturally tailored intervention promoting healthful eating and exercising. Anthropomorphic and self-administered questionnaire data were collected at a community health club site.

RESULTS

Controlling for demographic factors, overweight is associated with symptoms of depression, a relationship that is partially explained by health status, but not by dietary restraint. Using multiple regression, poor health status, alcohol intake, hostility, and low levels of ethnic identity (connectedness with the African-American community) are independent predictors of depressed mood. In this study, dietary restraint reflects healthful eating and is inversely related to depression. The overweight/depression association is stronger among women with high levels of education and high levels of ethnic identity (statistical interactions).

CONCLUSION

Poor health likely contributes over time to both overweight and depressed mood. Ethnic identity enhancement strategies should be studied for their effectiveness in strengthening identity and for their potential in attracting individuals especially likely to benefit from lifestyle change programs.

Physical activity among African American and Latino middle school girls: consistent beliefs, expectations, and experiences across two sites

Physical inactivity is a major public health concern. Low levels of physical activity are reported in many subgroups of women including adolescent girls. More data are needed to better understand factors related to physical activity participation in adolescent girls. Therefore, we explored adolescent girls' reasons for participating and not participating in physical activity. Two independent samples were taken in California and Texas; the total sample included thirty-four African American and Latino girls. Six focus groups were conducted by trained facilitators. Based on independent qualitative analyses, six replicated themes emerged from the focus groups. Fun, social support, and concern with body image facilitated participation in activity. In contrast, negative experiences in physical education classes, concerns about appearance after activity, and lack of opportunity impeded participation in activity. Overall, the girls showed an interest in physical activity and identified activity motivators and barriers. We discuss the implications of our findings for future research.

Measures of success and health-related quality of life in lower-extremity vascular surgery

Lower-extremity vascular surgery is most often indicated for patients with critical leg ischemia but has increasingly been used for patients with disabling intermittent claudication. This article reviews indications, follow-up protocols, and procedure-related outcomes including perioperative and late mortality, complications, and long-term patency rates, which vary with patient risk factors, vascular disease severity, and hospital volume. Population-based studies have yet to establish whether rates of limb-preserving bypass surgery are related to overall amputation rates, partly because of the continued high rate of primary amputation. The functional benefits of vascular surgery have been traditionally assessed by treadmill protocols and batteries of physical tests. Claudication treatment is increasingly being measured by both generic and disease-specific functional and health-related quality-of-life questionnaires. Patient self-reported measures of physical functioning and walking ability are reviewed. Finally, conclusions are presented about trends in lower-extremity bypass surgery rates.

Functional status and walking ability after lower extremity bypass grafting or angioplasty for intermittent claudication: results from a prospective outcomes study

OBJECTIVE

The purpose of this study was the prospective comparison of functional outcomes after lower extremity bypass grafting surgery, angioplasty, or medical management of intermittent claudication.

METHODS

The study was designed as a prospective cohort study to compare functional outcomes for patients with interventional management to medical management, including a matched (younger, with more disability) subgroup, followed for a mean of 19 months. Sixteen Chicago-area vascular surgery clinics participated in the study. The subjects were consecutively enrolled patients with an abnormal ankle-brachial blood pressure index (ABI), without signs of rest pain, ulcer, or gangrene, and without prior lower extremity revascularization procedures. The main outcome measures were changes in physical functioning, community walking distance, bodily pain, leg symptoms, and ABI.

RESULTS

Of the 526 study patients, 20% underwent revascularization procedures (60 surgical bypass grafting and 44 angioplasty only). The mean ABI improved significantly for the patients who underwent bypass grafting surgery (0.20; P <.001) and modestly for the patients who underwent angioplasty (0.09; P <. 05). Patients undergoing bypass grafting and angioplasty maintained highly significant (P <.001) improvements in mean physical functioning, (17%, 14%), bodily pain (18%, 13%), and walking distance (28%, 27%) scores and reported greater leg symptom improvement. The results were far superior for the patients with greater improvement in ABI. The conditions of the 277 unmatched patients who underwent medical management declined on all outcome measures, and the conditions of the 145 matched patients who underwent medical management improved 5% (P <.001) on walking distance score. Eighteen percent of the study patients failed to complete the full study follow-up period.

CONCLUSION

Most of the functional improvement achieved by patients who underwent interventional management appears to be related to improved patency rather than to selection bias or placebo effects. The functional gains were approximately half those often reported for patients for hip arthroplasty and similar to patients who undergo elective coronary angioplasty.

Reoperative aortic surgery

The presentation of long-term complications after conventional aortic surgery and the treatment of patients that have had reoperative aortic operations are reviewed. Ninety-seven consecutive patients that had 102 subsequent aortic operations at a tertiary referral center were studied. Presenting symptoms, demographics, risk factors, indications for initial and second procedures, operative techniques and outcomes were recorded in a computerized database. There were 70 men and 27 women studied, with an average age of 64 years. First operations were performed primarily for aneurysm (56%) and occlusive disease (44%). The interval between procedures ranged up to 23 years, with a mean of 6 years. Indications for reoperation were subsequent aneurysm (65), graft occlusions (25) and/or infections (24). Seventy-three percent of the subsequent aneurysms were true metachronous aneurysms; the others were associated with the graft or an anastomosis. Para-anastomotic aneurysms may be more common with a primary end-to-side graft configuration. One-third of subsequent aneurysms were not palpable and asymptomatic. Graft occlusion can be treated safely with elective repeat bypass (mortality 0%). Graft infections that require total graft removal remain a challenging problem (mortality 17%). Although surgical approach for reoperations utilized more extensive exposure and proximal clamping, 59 elective aneurysm cases had a 5.1% mortality rate; eight emergent procedures for ruptured aneurysms resulted in 88% mortality. Reoperation for graft occlusion or infection showed a similar high mortality rate with emergent cases. In this referral practice, graft occlusion and infection are relatively less frequent, whereas metachronous aneurysm formation is now the most common indication for reoperation. These aneurysms often remain undetected until symptoms occur; frank rupture is usually lethal. As elective repair with modern reoperative techniques can be safely performed, routine computed tomographic examination is advisable at least every 5 years after aortic operations.

Natural history of composite sequential bypass: ten years' experience

BACKGROUND

We previously reported 48-month patency rates of composite sequential bypass (CSB) approaching 60%. Yet, extended patency and limb salvage rates are unknown.

HYPOTHESIS

Long-term patency and limb salvage rates of CSB are affected by sex, bypass configuration, and warfarin therapy.

DESIGN

Medical records of all patients who underwent CSB during a 10-year period were retrospectively reviewed.

SETTING

A referral center for the Chicago, Ill, region.

PATIENTS

One hundred consecutive patients (mean age, 68.8 years; 57% were men and 49% had diabetes) undergoing 102 CSBs for limb salvage (ulcer, 43%; rest pain, 39%; and gangrene, 18%) from January 1986 to January 1996 were identified.

INTERVENTIONS

Warfarin was used after surgery by 72% of patients and aspirin was used by the remainder of them.

MAIN OUTCOME MEASURES

Life table primary patency and limb salvage rates were compared for sex, diabetes mellitus status, location of distal prosthetic anastomosis (above knee vs. below knee), and anticoagulation drug therapy (warfarin sodium vs aspirin) with log-rank statistics.

RESULTS

Primary patency of CSB was 56% at 24 months, 29% at 48 months, and 20% at 84 months (SE <10%; mean follow-up, 19.6 months [range, 1.0-110.0 months]). Limb salvage rates were 64% at 24 months, 30% at 48 months, and 23% at 84 months (SE <10%); 66% and 90% of patients had failed grafts requiring amputation by 3 months and 1 year, respectively.

CONCLUSIONS

Composite sequential bypass for limb salvage provides reasonable 2-year patency. However, patency rates steadily declined from year 2 to year 5. After CSB failure, limb salvage rates are poor, with 90% of patients progressing to amputation within 1 year.

Comparing three preprocessing strategies for longitudinal data. An example in functional outcomes research

Longitudinal monitoring of individual patient data is becoming routine in physician office practice. This study compares three different methods for evaluating clinical outcomes for individual patients: raw change score analysis versus normative and ipsative statistical analyses. Two discrete samples of intermittent claudication patients making vascular surgery office visits--drawn from interventional management versus stable, routinely followed control groups--were tested four times using both generic and disease-specific functional status measures. Results indicated that the ipsative method was most consistent with several different types of a priori hypotheses that are often evaluated in analysis of repeated measures data.

Combined arterial reconstruction and free tissue transfer for limb salvage

PURPOSE

Lower-extremity arterial anatomy that is insufficient for successful vein bypass grafting and major proximal foot wounds often lead to leg amputation in patients with severe ischemia. Free tissue transfer, which can provide limb salvage in these patients after arterial reconstruction, was studied.

METHODS

During a 45-month period, 21 patients who otherwise would have undergone leg amputation were treated with arterial bypass by means of vein grafting and free tissue transfer. Ages of the patients ranged from 40 to 73 years (average, 59 years); 18 of the 21 patients had diabetes mellitus; and all patients except one were men. Arterial reconstruction was performed from the femoral (nine of 21 patients) or popliteal artery (12 of 21 patients) to the posterior tibial (eight patients), dorsalis pedis (five patients), peroneal (three patients), popliteal (one patient), or anterior tibial artery (one patient), or directly to the free flap (three patients). The tissue transferred included latissimus dorsi (five patients), rectus abdominus (five patients), omentum (five patients), gracilis (two patients), radial forearm flaps (three patients), and a scapular flap (one patient). Foot defects were debrided, including the appropriate toe or transmetatarsal amputation, covered with the transferred flap, and then split-thickness skin grafted. Arterial flow for all flaps was through the vein grafts, with direct arterial anastomosis and with venous outflow through adjacent tibial veins.

RESULTS

All 21 procedures were successful initially, without operative mortality, but three failed within 4 weeks because of uncontrolled infection (two) or embolization from a remote site (one) and required below-knee amputation. Grafts remained patent in 18 procedures, and follow-up of this cohort ranged from 1 to 45 months (mean, 13.3 months). Two patients died, one after 4 months and one after 6 months, of unrelated illness; at the time of death, they had functioning grafts. The remaining 19 patients are alive. Of these, 15 have patent arterial grafts, all viable free flaps. Thus, limb salvage was accomplished in 18 of 21 (86%) patients who otherwise would have required below-knee amputation.

CONCLUSION

Patients destined for leg amputation despite aggressive traditional arterial bypass grafting methods can achieve limb salvage with the additional technique of free tissue transfer.

Thoracoscopically-assisted thoraco-femoral bypass in a canine model

Interest in minimally invasive procedures for vascular disease has grown tremendously over the past few years. Herein, we report our initial experience with a thoracoscopically-assisted thoraco-femoral bypass in a larger animal model. Included are various approaches to a final recommendation for the technique.

Minimally invasive thoracoscopic thoraco-femoral bypass: a case report

Thoracoscopic techniques have improved a variety of thoracic surgical procedures. Thoraco-femoral bypass is an exceptional alternative to standard thoracoscopic thoraco-femoral bypass. Herein we report our initial human experience with a thoracoscopic thoraco-femoral bypass.

Mentholated cigarette smoking and lung-cancer risk

PURPOSE

Menthol smoking may lead to a greater increase in lung-cancer risk than smoking of nonmentholated cigarettes. Mentholation of cigarettes adds additional carcinogenic components to cigarette smoke and increases retention times for cigarette smoke in the lungs. Only two epidemiologic studies have been conducted on menthol smoking and lung cancer, and their results are conflicting. Of note, African American males have much higher rates of lung cancer than Caucasian males despite smoking fewer cigarettes per day. Because the consumption of menthol cigarettes is much more frequent among African Americans, it is of interest to examine the possible association between menthol smoking and lung-cancer risk in this population.

METHODS

We examined the association between menthol cigarette smoking and lung-cancer risk among smokers by comparing 337 incident cases of lung cancer with 478 population controls enrolled in a case-control study of lung cancer. Information on smoking history and other known and potential risk factors for lung cancer, including dietary intake, was obtained by in-person interviews.

RESULTS

The adjusted odds ratios did not differ appreciably between smokers of mentholated cigarettes versus exclusive nonmentholated cigarette smokers in the overall study group of smokers. The odds ratio (OR) for 32 pack-years or more of mentholated vs. nonmentholated cigarettes was 0.90 (95% confidence interval (CI) = 0.38-2.12) in African Americans and 1.06 (95% CI = 0.47-2.36) in Caucasians, and did not differ for either ethnic group (p = 0.98).

CONCLUSIONS

Our results suggest that the lung-cancer risk from smoking mentholated cigarettes resembles the risk from smoking non-mentholated cigarettes. Our data do not support the hypothesis that the increased risk of lung cancer among African Americans is due to the increased prevalence of menthol smoking.

Carotid plaque morphology correlates with presenting symptomatology

PURPOSE

In carotid artery disease, correlation of carotid plaque morphology with the patient's presenting symptoms has drawn conflicting conclusions. The purpose of this series was to correlate carotid plaque characteristics with the presenting symptoms from a large cohort of patients who underwent operation for carotid artery disease.

METHODS

From a series of 1252 consecutive patients who underwent carotid endarterectomy, presenting symptoms were divided into three groups: transiently symptomatic (transient ischemic attack [TIA] or amaurosis fugax), prior stroke, and asymptomatic. Plaque characteristics, including ulceration, intraplaque hemorrhage, and degree of stenosis, were recorded prospectively for 1008 procedures. All endarterectomy specimens were inspected during the procedure, and plaque characteristics were recorded immediately after operation.

RESULTS

There was a higher incidence of plaque ulceration in the transiently symptomatic and prior stroke groups (391 of 508 [77%] and 91 of 115 [79%]) than in the asymptomatic cohort (231 of 385 [60%]; p < 0.0001, chi2 test). There was no significant difference in the incidence of plaque hemorrhage between the transiently symptomatic and prior stroke patients compared with the asymptomatic patients. There was no statistical difference for ulcerated plaque or plaque hemorrhage between the transiently symptomatic and prior stroke group. Intraplaque hemorrhage occurred more frequently in patients with high-grade stenosis (90% to 99%) than in those with less than 90% stenosis (202 of 299 [68%] versus 97 of 299 [32%]; p = 0.01, chi2 test).

CONCLUSIONS

On gross examination of the carotid specimen in the operating room, plaque ulceration correlates with an initial presentation of amaurosis fugax, TIA, or prior stroke compared with patients operated on for asymptomatic disease. The presence of intraplaque hemorrhage is associated with more advanced stenosis of the internal carotid artery. These findings suggest that plaque morphology does play an important role in the presentation of carotid artery disease.

A classification tree analysis of selection for discretionary treatment

OBJECTIVES

To study treatment bias in observational outcomes research, the authors present a nonlinear classification tree model of clinical and psychosocial factors influencing selection for interventional management (lower extremity bypass surgery or angioplasty) for patients with intermittent claudication.

METHODS

The study sample includes 532 patients with mild to moderate lower extremity vascular disease, without prior peripheral revascularization procedures or symptoms of disease progression. All patients were enrolled in a prospective outcomes study at the time of an initial referral visit for claudication to one of the 16 Chicago-area vascular surgery offices or clinics in 1993-95. The influence of baseline sociodemographic, clinical, and patient self-reported health status data on subsequent treatment is analyzed. Study variables were derived from lower extremity blood flow records and patient questionnaires. Follow-up home health visits were used to ascertain the frequency of lower extremity revascularization procedures within 6 months of study enrollment. Hierarchically optimal classification tree analysis (CTA) was used to obtain a nonlinear model of treatment selection. The model retains attributes with the highest sensitivity at each node based on cutpoints that maximize classification accuracy. Experimentwise Type I error is ensured at P < 0.05 by the Bonferroni method and jackknife validity analysis is used to assess model stability.

RESULTS

Seventy-one of 532 patients (13.3%) underwent interventional procedures within 6 months. Ten patient attributes were used in the CTA model, which had an overall classification accuracy of 89.5% (67.6% sensitive and 92.9% specific), achieving 57.7% of the theoretical possible improvement in classification accuracy beyond chance. Eleven model prediction endpoints reflected a 33-fold difference in odds of undergoing lower extremity revascularization.

CONCLUSIONS

Initial ankle-brachial index (100%), leg symptom status over the previous six months (89%), self-reported community walking distance (74%) and prior willingness to undergo a lower extremity hospital procedure (39%) were used to classify most patients in the sample. These attributes are critical control variables for a valid observational study of treatment effectiveness.

Treatment of venous malformations by direct injection with ethanol

PURPOSE

Venous malformations (VMs) may be discrete or extensive, and larger lesions may be difficult to remove with surgery. Incompletely removed lesions have a tendency to recur. We report our experience with ethanol ablation of VMs.

METHODS

All 12 patients (seven women; mean age, 37 years) were evaluated with magnetic resonance imaging before treatment. A total of 19 prior surgical excisions had been performed for seven of the patients. Symptoms were present in all 12 patients and included bleeding, pain, swelling, and limitation of exercise. The VMs were present in the lower extremities of seven patients, in the upper extremities of three patients, and in the flank and buttocks in two patients.

RESULTS

The 12 patients have undergone 30 injection procedures, with six patients requiring one, three patients requiring two, two patients requiring three, and one patient having undergone 12 treatments. General anesthesia was used in 11 patients. Blood loss was minimal for all procedures, and 28 of the 30 procedures were technically successful. Skin ulceration was seen in approximately half of the treated VMs, all of which healed with local wound care. Focal VMs were injected in six patients and resolved with a single treatment in five patients. Patients were free of symptoms at a mean follow-up of 10 months. Extensive VMs were injected for discrete, symptomatic areas in five patients. These lesions all regressed and were asymptomatic at a mean follow-up of 23 months in all but one patient. However, these lesions required multiple treatments as additional areas became problematic.

CONCLUSIONS

Ethanol sclerosis is a well-tolerated, safe, and effective adjunct to the management of VMs. Advantages of ethanol injection include the ability to treat a very localized area without an incision. Conversely, extensive lesions may be palliated as symptoms occur.

Perioperative low molecular weight heparin for infrageniculate bypass

PURPOSE

Recent studies suggest that subcutaneous low molecular weight heparin (LMWH) is a safe, effective alternative to intravenous heparin (IVH) for deep venous thrombosis. LMWH may also be a safe, effective alternative to IVH when necessary for lower extremity bypass procedures performed with polytetrafluoroethylene (PTFE) grafts. The purpose of this study was to compare subcutaneous LMWH with IVH for perioperative anticoagulation in patients who underwent infrageniculate bypass procedures with PTFE grafts.

METHODS

Of 361 lower extremity bypass operations performed at a single center over a 32-month period, 76 were to the tibial or below-knee levels using PTFE grafts for limb salvage. Seven patients were excluded because of absolute indications for perioperative IVH (ventricular thrombus in 1 patient, prosthetic valve in 2, cardiac dysrhythmia in 2, and documented hypercoagulable syndrome in 2), leaving 68 patients (35 women; mean age, 69.8 years) with 69 bypass procedures for study. Grafts completed in the past 16 months were treated with LMWH (28 grafts; Oct. 1994 to Jan. 1996) and were compared with 41 consecutive control grafts from the previous 16-month interval (Apr. 1993 to Oct. 1994) who received IVH. There were similar percentages of composite bypasses (IVH, 50%; LMWH, 46%), patients with tissue loss or gangrene (IVH, 56%; LMWH, 61%), and patients with prior ipsilateral bypass (IVH, 57%; LMWH, 56%) in each group. Age, sex, and atherosclerotic risk factors were also similar between the two groups.

RESULTS

Morbidity rates (IVH, 19%; LMWH, 11%) and mortality rates (IVH, 2.5%; LMWH, 4%) were not significantly different. There were no significant differences in the number of grafts that failed before discharge (IVH, 1; LMWH, 0) or percentage of hemorrhagic complications (IVH, 15%; LMWH, 7%). The mean number of postoperative hospital days (IVH, 9.5; LMWH, 7.2; p < 0.009) and coagulation monitoring studies (IVH, 22; LMWH, 8.4; p < 0.0001) were significantly decreased in patients who were anticoagulated with LMWH. The mean number of days before conversion to oral anticoagulation (IVH, 7.3; LMWH, 8.0) did not differ significantly.

CONCLUSIONS

When perioperative anticoagulation is deemed necessary, LMWH provides a safe, effective alternative to IVH for infrageniculate PTFE bypass grafting procedures. LMWH may reduce the number of postoperative hospital days and coagulation studies by allowing discharge before therapeutic anticoagulation with warfarin.

Cytolytic activity of Bacillus thuringiensis CryIC and CryIAc toxins to Spodoptera sp. midgut epithelial cells in vitro

A sensitive lactate dehydrogenase (LDH) assay was modified to determine the cytolytic activity of Bacillus thuringiensis CryIC and CryIAc delta endotoxins to viable collagenase-dissociated midgut epithelial cells (MEC) from larvae of Spodoptera frugiperda and Spodoptera exigua. The MEC preparations from these Spodoptera sp. consisted predominantly of columnar cells (65-75%) and goblet cells (25-35%). Time course microscopy experiments indicated that only the columnar cells became swollen during CryIC toxin incubation. Also, comparative cytotoxicity studies were run with cell lines of nonmidgut origin established from S. frugiperda (SF21AE) and S. exigua (SEUCR1A). Optimum conditions for the cytotoxicity assay were similar for MEC and cell lines of both species, and were met in an assay in which 0.1-ml cell concentrations (8.5 +/- 0.5 x 10(4) cells) were incubated with toxin dilutions (0.01-20 micrograms) for 1 h at 24 degrees C at a final pH of 7.8. The Spodoptera sp. MEC were twofold more sensitive to CryIC (68% lysis) than CryIAc (32% lysis) at optimum toxin levels (2.5-5 micrograms). Also, the SEUCR1A cells were more sensitive (2.3-fold) to CryIC (70% lysis) than CryIAc (30% lysis) at optimum toxin levels of 5-10 micrograms. The SF21AE cells, however, were twofold less sensitive to CryIC (30% lysis) than SEUCR1A cells and response to CryIAc and CryIC was similar. Immunoblot analysis of either Spodoptera sp. MEC or brush border membrane vesicles (BBMV) identified seven CryIC binding proteins with molecular mass of 137, 120, 115, 68, 65, 63, and 45 kDa. Occasionally, a 148-kDa protein band was observed. The CryIAc toxin bound to two proteins on MEC and BBMV with molecular mass of 137 and 120 kDa.

Sarcoma arising from an abdominal aortic aneurysm

A rare case of retroperitoneal sarcoma arising from an aneurysm sac is diagnosed in a patient following tube graft repair of the abdominal aortic aneurysm. The radiographic studies illustrate the characteristics of malignancy which are distinguishable from more common vascular complications. Malignancy should be considered in the differential diagnosis of retroperitoneal masses during radiographic follow-up of patients after aortic surgery. Sarcoma is optimally treated with complete excision, sometimes requiring concomitant vascular reconstruction. Radical en bloc resection was not attempted in this case due to extensive involvement of the aorta and inferior vena cava.

Elevations of tissue-type plasminogen activator and differential expression of urokinase-type plasminogen activator in diseased aorta

PURPOSE

Elevations of plasmin have been implicated in the pathogenesis of abdominal aortic aneurysms (AAA) because of its ability to digest extracellular matrix proteins. Plasminogen activators regulate the conversion of plasminogen to plasmin. Tissue-type plasminogen activator (tPA) is more important in modulation of fibrinolysis, and urokinase-type plasminogen activator (uPA) is predominant in tissue remodeling. The purpose of this study was to determine the levels of plasminogen activators in diseased aorta because they may be responsible for the increased plasmin levels previously described in AAA.

METHODS

Levels of tPA and uPA in AAA, occlusive, and normal (organ donor) aorta were studied in tissue explant supernatants. Supernatant tPA and uPA levels were measured with an enzyme-linked immunosorbent assay. Northern analysis was used to quantitate uPA messenger RNA (mRNA) levels in aortic tissue.

RESULTS

Levels of tPA in the supernatants were similar in occlusive (20 +/- 4 ng/ml) and AAA (23 +/- 8) aorta, but threefold higher than in normal aorta (7 +/- 5; p < 0.005 for normal vs occlusive and p < 0.001 for normal vs AAA). In contrast, uPA supernatant levels were differentially expressed, with the highest level existing in AAA (9.7 +/- 2.7 ng/ml), followed by occlusive (4.9 +/- 3.5), and the lowest levels in normal aorta (1.2 +/- 0.7; p < 0.05 for normal vs occlusive, p < 0.001 for normal vs AAA, and p < 0.005 for occlusive vs AAA). Inhibition of protein or RNA synthesis by addition of cyclohexamide or actinomycin D, respectively, revealed no significant difference between treated and control supernatants, suggesting that the increases were caused by protein release rather than active synthesis. Levels of uPA mRNA followed the same trend as the supernatant uPA levels (AAA 1.07 +/- 0.54, occlusive 0.54 +/- 0.08, and normal aorta 0.01 +/- 0.01).

CONCLUSIONS

Levels of tPA were similar in aneurysmal and occlusive aorta, but exhibited a threefold increase over normal aorta, suggesting that the elevations of tPA are associated with the arteriosclerosis present in both aneurysmal and occlusive disease. Differences in uPA levels were significant between all three groups, with the highest levels in AAA and the lowest levels in normal specimens. Northern analysis of uPA mRNA followed the same trend, suggesting that the increase in uPA may be regulated at the level of transcription. As uPA plays an important role in tissue remodeling, our findings may also reflect the relative tissue repair activities in these three types of specimens and may explain the previously reported increased levels of plasmin seen in AAA.

Reduction in aortic aneurysm size: early results after endovascular graft placement. EVT Investigators

PURPOSE

Previous reports demonstrate initial technical success with transluminally placed endovascular grafts (TPEG) for the treatment of abdominal aortic aneurysms. However, long-term changes in the size of the aorta and aneurysmal segments are unknown. The purpose of this study was to determine aortic dimensions at several levels by computed tomographic (CT) scans 1 year after TPEG.

METHODS

Thirty-four patients underwent TPEG with 1-year CT scans. Patients were divided into three groups: group I, no perigraft leak; group II, early perigraft leak that sealed during the first year; and group III, persistent perigraft leak. Aortic minor and major diameters, perimeter, and area were measured at four locations: the celiac aorta, proximal neck, maximal aneurysm size, and distal neck.

RESULTS

There were 32 men and two women, with a mean age of 73 +/- 8 years. In group I there were 20 patients (58%), and groups II and III had seven patients (21%) each. The overall mean aneurysm minor diameter decreased from 4.79 +/- 0.68 cm at implantation to 4.39 +/- 0.86 cm at 1 year (p < 0.0001). The aneurysm sac decreased by 0.63 +/- 0.58 cm in group I, and by 0.34 +/- 0.24 cm in group II. In group III, however, the aneurysm sac increased by 0.19 +/- 0.21 cm. Aneurysm size change did not correlate with inferior mesenteric or lumbar artery patency. The dimensions of the celiac aorta and proximal neck did not change significantly. However, diameter of the distal neck enlarged by 0.12 +/- 0.27 cm (p < 0.01).

CONCLUSIONS

TPEG exclusion is associated with reduction of aneurysm size 1 year after implantation. Expansion of the aneurysms occurred with persistent perigraft leak. The aortic size at the celiac artery and proximal neck did not change. Dilation of the distal neck was minor but requires further long-term follow-up to determine clinical significance.

Plasminogen activator levels are influenced by location and varicosity in greater saphenous vein

PURPOSE

The plasminogen system, which includes tissue type plasminogen activator (tPA), urokinase type plasminogen activator (uPA), and their main inhibitor, plasminogen activator inhibitor type 1 (PAI-1), plays a major role in both fibrinolysis and tissue remodeling. This study compares the levels of tPA, uPA, and PAI-1 at the groin and ankle in normal and varicose greater saphenous vein (GSV).

METHODS

GSV was collected from patients undergoing varicose vein (VV) removal and from normal vein (NV) from arterial bypass procedures. Portions of the GSV at the groin and the ankle were minced and placed in serum-free media for 48 hours. Assays of the supernatants were obtained for tPA, uPA, and PAI-1 protein by enzyme-linked immunosorbent assay. Cyclohexamide and actinomycin D were also added to the media of the VV tissue explant supernatants to inhibit protein and RNA synthesis, respectively.

RESULTS

Levels of tPA were significantly higher at the groin (11 +/- 2) than the ankle (5 +/- 1) in the VV (p < 0.005), and this trend was also seen in the NV (groin 10 +/- 2 and ankle 7 +/- 3). Levels of uPA were significantly higher in the groin VV (14 +/- 4.3) than in NV (3.0 +/- 0.8, p < 0.05). This difference, although not statistically significant, applied to the ankle as well (VV 14.5 +/- 6.3 and NV 5.3 +/- 2.7). No significant difference was seen between NV and VV for PAI-1 (NV, groin 155 +/- 73 and ankle 113 +/- 53, VV, groin 161 +/- 20 and ankle 142 +/- 38) or tPA. Inhibitor studies revealed no significant difference among control, cyclohexamide, and actinomycin D supernatants for tPA, suggesting release of protein rather than active synthesis. In contrast, inhibitor supernatants were significantly lower for uPA and PAI-1 than control supernatants (p < 0.05), suggesting that uPA and PAI-1 were actively synthesized.

CONCLUSIONS

In the tissue explant supernatant model uPA and PAI-1 are actively synthesized, but tPA is not. Levels of PAI-1 were comparable in all four groups. Levels of uPA in the varicose GSV were higher than in NV, suggesting a role for uPA in the pathologic makeup of VV. Levels of tPA were higher at the groin versus the ankle position, potentially explaining the previously described increased fibrinolytic activity seen at the groin.

Peripheral vascular disease in spinal cord injury patients: a difficult diagnosis

The timely detection of peripheral vascular disease (PVD) in spinal cord injury (SCI) patients is difficult because the usual symptoms of claudication and rest pain are absent. In fact, the initial manifestation of PVD in SCI patients is often advanced gangrene, so that healing, primarily or following major amputation, is either difficult and prolonged or impossible. In addition, sacral and ischial pressure sores common among SCI patients may be exacerbated and reconstruction made more difficult by PVD. Five SCI patients presented with lower extremity gangrene as the initial recognized manifestation of PVD at our institution between January 1992 and January 1994. All 5 patients had risk factors for PVD. Four out of ten limbs in these patients required amputation, either above the knee or below the knee. Three patients required concurrent vascular reconstruction of the aortoiliac segments, including an aortobiprofunda femoral bypass, an iliac embolectomy with femoral-femoral bypass, and iliac angioplasty. Three patients had ischial and/or sacral pressure sores that had recurred following multiple musculocutaneous flap reconstructions before vascular disease was recognized. The timely diagnosis of PVD involving the iliac segment in the SCI patient is sometimes overlooked and is often necessary to optimize the treatment of both lower extremity ulcers and sacral/ ischial pressure sores common among these patients.

Current management of visceral artery aneurysms

BACKGROUND

Visceral artery aneurysms are an uncommon but important form of abdominal vascular disease. This study reviews a contemporary experience with special emphasis on newer methods of diagnosis and treatment.

METHODS

From 1980 to 1994, 37 patients were diagnosed with 46 visceral artery aneurysms. These consisted of 22 splenic, 10 hepatic, 4 superior mesenteric, 2 gastroduodenal, 3 celiac, 2 left gastric, 1 pancreatoduodenal, 1 jejunal-ileal, and 1 inferior mesenteric artery aneurysms. Follow-up was complete for 28 patients, average of 37.7 months. There were 17 asymptomatic and 29 symptomatic aneurysms, including 11 presenting with rupture.

RESULTS

Seventeen patients were treated surgically, with no surgical deaths. Surgical complications included splenic abscess (two) and failure to thrombose (one). Transcatheter embolization was used in 12 patients. Complications included splenic infarction (one) and recurrence (two), successfully treated with repeat embolization. Nine patients were treated with observation. Eight experienced no complications during follow-up; one died of a ruptured splenic artery aneurysm before treatment was initiated.

CONCLUSIONS

The widespread use of computed tomography has led to increased detection of asymptomatic visceral artery aneurysms. Although surgery remains necessary in many patients, transcatheter embolization is effective in the treatment of selected visceral artery aneurysms with few complications and low recurrence.

Effect of lower extremity blood pressure on physical functioning in patients who have intermittent claudication. The Chicago Claudication Outcomes Research Group

PURPOSE

Claudication patients' perceptions of walking impairment often influence recommendations for peripheral bypass and angioplasty. The actual relationship between lower extremity blood flow and physical functioning, however, has rarely been explicitly studied.

METHODS

Patients were enrolled at a visit to one of 16 vascular surgery offices and clinics that participated in a prospective outcomes study. A total of 555 patients (445 men and 110 women) with an abnormal ankle-brachial index (ABI), none of whom had had previous leg revascularization or symptoms of rest pain, skin ulcers, or gangrene, completed the SF36 Health Survey and the Peripheral Arterial Disease Walking Impairment Questionnaire (WIQ). Stepwise multiple regression analysis was used to test the statistical significance and strength of association between patients' ABI level and SF36 physical functioning (PF) and WIQ community walking distance scores, controlled for sociodemographic characteristics and the presence and severity of comorbid conditions.

RESULTS

Univariate correlations with ABI were modest but significant (PF score, r = 0.12, p = 0.004; WIQ distance score, r = 0.18, p < 0.001). ABI was a very significant predictor of both PF (b = 18.8; p = 0.001) and WIQ scores (b = 0.33; p < 0.0001) in the multiple regression analysis. Other positive predictors of PF scores were high-school graduation and male sex. Negative predictors of PF scores were heart, lung, and cerebrovascular disease; knee arthritis and chronic back pain; and enrollment at a Veterans Administration clinic rather than a private community or academic office.

CONCLUSION

Cross-sectional findings indicate that a 0.3 improvement in ABI is associated with an average improvement of 5.6% in PF or 10.3% in WIQ distance score. However, proper selection of individual candidates for interventional therapy, that is, those patients who have lower ABIs, lower initial functioning, and fewer disabling comorbidities would be predicted to produce a much greater functional benefit. Surgeons should make a rigorous functional evaluation when recommending interventional management of claudication.

Carotid endarterectomy. Lessons from intraoperative monitoring--a decade of experience

OBJECTIVE

The authors analyzed a single institution's 10-year experience with intraoperative monitoring during 709 primary carotid endarterectomies and investigated the impact of contralateral internal carotid artery stenosis on carotid artery stump pressure (SP).

SUMMARY BACKGROUND DATA

Stump pressure reflects the combination of contralateral carotid artery anatomy, collateral intracranial vasculature, and systemic blood pressure. By controlling for blood pressure with a stump index (SI) (SI = [SP/mean arterial pressure] x 100), a correlation between pressure and contralateral carotid artery anatomy can be demonstrated. Although the use of SP has long been advocated as an indicator of adequate cerebral perfusion, its correlation with perioperative complications while using an intraluminal shunt has not been evaluated completely.

METHODS

From a series of 886 primary carotid endarterectomy cases, SP and mean arterial pressure were measured prospectively in 709 procedures. Temporary intraluminal shunts were used in cases with demonstrated contralateral carotid occlusion, prior cerebrovascular accident (CVA), or SPs less than 35 mmHg. Ipsilateral and contralateral angiographic degree of carotid stenosis was recorded at the time of the operation. Neurologic status was recorded prospectively for all 709 procedures. Operative electroencephalogram (EEG) changes and SP then were compared with the neurologic status of the patient in the perioperative period.

RESULTS

The mean SP for the group (n = 709) was 46.7 +/- 15.3 mmHg (mean +/- standard deviation [SD]) with a mean SI of 54.9 +/- 22.6. The distribution for the SI is a more gaussian curve than that for SP. There were 19 ipsilateral CVAs (2.7%). The mean SP in the nonstroke group was 47.1 +/- 15.2 mmHg (mean SI = 54.7 +/- 16.5) compared with 31.9 +/- 13.2 mmHg (mean SI = 38.8 +/- 18.2) in the stroke group (P < 0.0001). Stroke rate for SP < or = 35 mmHg was 7% (13/185) versus 1.1% (6/524) for SP > 35 (p < 0.0001). Stump index and SP are related to contralateral carotid artery stenosis. The pattern of SI or SP versus contralateral stenosis is biphasic, with an increase at 75%. If SI is < or = 40, the mean contralateral stenosis is 55.1%; if SI is > 40, the mean contralateral stenosis is 35.1% (p < 0.05). Continuous EEG monitoring was completed for the 549 most recent operations. Patients who had a perioperative stroke had EEG changes observed during the procedure in only 6 of 12 cases (50% sensitivity), with 76% specificity. Using SP < or = 35 mmHg, sensitivity was 68% and specificity was 75%.

Elevated levels of plasminogen-activator inhibitor type 1 in atherosclerotic aorta

PURPOSE

Plasminogen activator inhibitor type I (PAI-1) inhibits the plasminogen activators that convert plasminogen to plasmin. In addition to initiating fibrinolysis, plasmin activates tissue matrix metalloproteinases, which cause degradation of the extracellular matrix (ECM) in the arterial wall. Elevated levels of PAI-1 ultimately decrease plasmin formation and may lead to an accumulation of ECM and arteriosclerosis.

METHODS

PAI-1 was studied by four methods in atherosclerotic (aneurysmal and occlusive) and normal (organ donor) aorta: (1) PAI-1 secretion by tissue explant supernatants, including time course and inhibition studies; (2) tissue PAI-1 by protein extraction; (3) PAI-1 mRNA was quantitated by Northern analysis using glyceraldehyde-3-phosphate dehydrogenase to normalize for RNA loading; and (4) in situ hybridization was used to localize the cells that produced PAI-1 mRNA.

RESULTS

Supernatant PAI-1 levels at 48 hours were 776 +/- 352, ng/ml in 11 atherosclerotic aortas and 248 +/- 98 ng/ml in 8 normal aortas (p < 0.005). Tissue PAI-1 levels per 100 mg of tissue were 99 +/- 58 ng in 11 atherosclerotic aortas and 38 +/- 20 ng in 5 normal aortas (p < 0.05). PAI-1 mRNA levels by Northern analysis were 0.91 +/- 0.49 in seven atherosclerotic aortas and 0.44 +/- 0.27 in five normal aortas. Supernatant time-course experiments revealed that PAI-1 increased over time. Inhibitor studies revealed that PAI-1 decreased to approximately one third of control values when cycloheximide or actinomycin D were added to the media, indicating that active synthesis of PAI-1 had occurred. In-situ hybridization localized PAI-1 mRNA predominately to endothelial cells and a few scattered vascular smooth muscle and inflammatory cells. Subgroup analysis revealed no statistically significant differences between aneurysmal and occlusive PAI-1 levels in any of the experiments.

CONCLUSION

PAI-1 secretion, as measured by tissue explant supernatants, and total tissue PAI-1 in the protein extracts were significantly increased in atherosclerotic aorta. This elevation was also observed in the mRNA, which suggests that the increase is controlled at the level of transcription. PAI-1 mRNA was localized to endothelial, vascular smooth muscle, and inflammatory cells. We conclude that elevated levels of PAI-1 exist in diseased aorta. These elevated levels may lead to an accumulation of ECM, thereby contributing to the arteriosclerosis found in aortic occlusive and aneurysmal disease.

Simultaneous abdominal aortic aneurysm repair and nephrectomy for neoplasm

BACKGROUND

Abdominal aortic aneurysm and renal neoplasm are occasionally discovered concurrently. Simultaneous operative therapy may be an effective alternate management strategy to a staged procedure.

PATIENTS AND METHODS

The medical records of 10 consecutive patients undergoing abdominal aortic aneurysm repair and nephrectomy for renal neoplasm were reviewed. Data collected included mode of presentation, preoperative evaluation, renal pathology, and in-hospital morbidity and mortality. Long-term follow-up was obtained through office records and telephone contact.

RESULTS

In 7 patients, the renal mass was identified during evaluation of abdominal aortic aneurysm. The aneurysm was identified during evaluation of hematuria in 2 patients. One patient was discovered to have both conditions simultaneously. All patients underwent successful aneurysm repair and nephrectomy. Pathology revealed 6 renal cell carcinomas, 2 complex cysts, 1 hemangiopericytoma, and 1 oncocytoma. Four patients have died in the follow-up period: 1 of metastatic cancer and 3 of unrelated causes. There have been no cases of graft infection.

CONCLUSION

Simultaneous abdominal aortic aneurysm repair and nephrectomy for neoplasm is an appropriate management strategy for selected patients.

Surgical management of atheroembolization

PURPOSE

Atheroembolization may cause limb loss or organ failure. Surgical outcome data are limited. We report the largest series of atheroembolization focusing on patterns of disease, surgical treatment and outcome.

METHODS

One hundred patients (70 men), mean age 62 +/- 11 years, operated on for lower extremity, visceral, or nonthoracic outlet upper extremity atheroemboli were identified prospectively and monitored over a 12-year period. The atheroembolic source was localized by use of a combination of computed tomography scanning (n = 55), arteriography (n = 93), duplex scanning (n = 25), transesophageal echocardiography (n = 6), and magnetic resonance imaging (n = 4). Occlusive aortoiliac disease (47 patients) and small aortic aneurysms (20 patients; mean aneurysm size 3.5 +/- 0.8 cm) were the most common source of atheroemboli. Imaging studies revealed 12 patients with extensive suprarenal aortic thrombus. Correction of the embolic source was achieved with aortic bypass (n = 52), aortoiliac endarterectomy and patch (n = 11), femoral or popliteal endarterectomy and patch (n = 11), infrainguinal bypass (n = 3), extraanatomic reconstruction (n = 6), graft revision (n = 3), upper extremity bypass (n = 11), or upper extremity endarterectomy and patch (n = 3).

RESULTS

All four deaths within 30 days and all seven deaths within the first 6 months after operation were among the 12 patients with suprarenal aortic thrombus. The cumulative survival probabilities for all patients at 1, 3, and 5 years were 89%, 83%, and 73%, respectively. After operation, nine patients required major leg amputations and 10 required toe amputations. Renal atheroemboli led to hemodialysis in 10 patients. Recurrent embolic events occurred in five of 97 patients monitored for a mean of 32 months. All five recurrences occurred in the first 8 months after operation. Three patients with recurrent emboli had suprarenal aortic disease, one of whom had undergone axillofemorofemoral bypass. Four of 15 patients receiving postoperative warfarin anticoagulation had development of recurrent embolism. Only one patient not receiving postoperative warfarin had a recurrent event (p < 0.05 by Fisher exact test).

CONCLUSION

The atheroembolic source is the aorta or iliac arteries in two thirds of patients who underwent operation. Computed tomography scanning of the aorta is a useful diagnostic technique. The source of the emboli can be eliminated surgically with low mortality or limb loss rates except when the suprarenal aorta is involved.

Mesenteric artery bypass: objective patency determination

PURPOSE

Many authors have reported extended relief of intestinal ischemia by use of a variety of reconstructive techniques, but all have relied on symptomatic follow-up. None have objectively measured patency rates. The purpose of this study was to determine the primary patency rates of bypass grafts placed for acute and chronic splanchnic atherosclerotic occlusive disease with use of objective follow-up with mesenteric duplex ultrasound scanning or arteriography.

METHODS

Twenty-five consecutive patients (mean age 61, female/male ratio of 2.7:1) who underwent placement of 38 splanchnic bypass grafts (29 saphenous vein grafts, 9 polytetrafluoroethylene) (22 retrograde, 16 antegrade) for ischemic symptoms (9 acute ischemia: 16 chronic ischemia) between 1984 and 1994 were monitored with either duplex scanning (30 grafts) or arteriography. Life-table and log rank analysis were used to determine and compare graft patency.

RESULTS

Three patients (12%, 2 acute ischemia and 1 chronic ischemia) died after operation. Six patients (30%) had significant morbidity (4 acute ischemia and 2 chronic ischemia). During follow-up from 1 to 136 months (mean 35 months), no patient died of bowel infarction or required revision for recurrent symptoms. Objective testing revealed three graft occlusions. Symptomatic follow-up had a sensitivity of only 33% for graft occlusion when compared with objective measurement. The life-table primary patency rate was 89% at 72 months. Life-table survival for the same patients was 75% at 36 months. Patency rates for antegrade (93% at 36 months) versus retrograde (95% at 36 months) bypass and saphenous vein grafts (95% at 36 months) versus polytetrafluoroethylene (89% at 36 months) were not significantly different (p = 0.47 and 0.43, respectively). Late patency rates of grafts placed for acute ischemia (92% at 36 months) versus chronic ischemia (89% at 36 months) were not significantly different (p = 0.77).

CONCLUSION

Splanchnic bypass for mesenteric ischemia, with a primary patency rate of 89% at 72 months, is an extremely durable form of revascularization. Long-term patency of grafts placed for acute ischemia does not differ significantly from that of bypasses for chronic occlusion. Duplex scanning allows standardized objective periodic follow-up of splanchnic reconstruction. Objective assessment is critical to accurately measure visceral revascularization patency rates.

Menthol vs nonmenthol cigarettes: effects on smoking behavior

OBJECTIVES

The purpose of this study was to examine intraindividual differences in smoking behavior between smoking regular and mentholated cigarettes.

METHODS

Healthy male smokers (n = 29) smoked either a regular or a mentholated cigarette in two separate sessions 1 week apart. Commercial brands with comparable tar, nicotine, and CO content were used. Smoking behavior was constrained by fixed 15-second interpuff intervals, but puff volume and number of puffs were unconstrained.

RESULTS

When smoking the non-mentholated brand of cigarettes, participants smoked 22% more puffs and had 13% higher mean volumes per puff than they did when smoking the mentholated brand of cigarettes. The aggregate 39% excess exposure to cigarette smoke in the regular-cigarette condition was not accompanied by commensurate excesses in expired carbon monoxide or in physiological measures normally correlated with nicotine exposure.

CONCLUSIONS

These findings parallel differences in physiological correlates of exposure to nicotine found in cross-sectional comparisons of African-American and White smokers and are consistent with the results of emerging laboratory investigations.

Arterial injuries in the thoracic outlet syndrome

PURPOSE

This article reviews experience with arterial injury caused by thoracic outlet syndrome. Special emphasis is placed on the influence of athletic or work activities on the axillary-subclavian artery system and the mechanism by which the humeral head compresses the axillary artery and the circumflex humeral arterial branches.

METHODS

Retrospective review identified 34 patients (age range 13 to 67 years) treated for upper extremity symptoms or ischemic complications of thoracic outlet syndrome from 1983 to 1993. Evaluation included assessment of occupational and recreational activities plus duplex ultrasonography and contrast arteriography with positional maneuvers.

RESULTS

Twenty-two patients (27 arms) had subclavian artery injury, which was most commonly caused by compression by a bony abnormality (cervical rib, 16; anomalous first rib, two; cervical rib and anomalous first rib, two). Fourteen of the 27 arms had distal embolization. All 27 had surgical decompression of the subclavian artery; 15 required concomitant arterial reconstruction. Twelve additional patients (nine athletes) had axillary artery involvement, all from arterial compression by the head of the humerus during abduction maneuvers; all had concomitant compression of the posterior circumflex humeral artery. Axillary arterial injury included thrombosis (one), aneurysm (two), and symptomatic extrinsic compression only (nine). Five patients with axillary artery involvement were treated without a surgical procedure; of the remainder, three underwent decompression procedures only, and four had direct arterial repair. In both groups all subclavian and axillary artery reconstructions were patent at last follow-up examination (mean 31 months).

CONCLUSION

Most patients with thoracic outlet syndrome who have arterial involvement have a bony anomaly causing subclavian artery compression. This study demonstrates that humeral head compression of the axillary artery and its circumflex branches is a surprisingly common pathologic mechanism. Awareness of this condition affords a better therapeutic approach to arterial injuries caused by thoracic outlet syndrome.