Making informed choices on incorporating chemoprevention into carE (MiCHOICE, SWOG 1904): Design and methods of a cluster randomized controlled trial

INTRODUCTION

Women with atypical hyperplasia (AH) or lobular carcinoma in situ (LCIS) have a significantly increased risk of breast cancer, which can be substantially reduced with antiestrogen therapy for chemoprevention. However, antiestrogen therapy for breast cancer risk reduction remains underutilized. Improving knowledge about breast cancer risk and chemoprevention among high-risk patients and their healthcare providers may enhance informed decision-making about this critical breast cancer risk reduction strategy.

METHODS/DESIGN

We are conducting a cluster randomized controlled trial to evaluate the effectiveness and implementation of patient and provider decision support tools to improve informed choice about chemoprevention among women with AH or LCIS. We have cluster randomized 26 sites across the U.S. through the SWOG Cancer Research Network. A total of 415 patients and 200 healthcare providers are being recruited. They are assigned to standard educational materials alone or combined with the web-based decision support tools. Patient-reported and clinical outcomes are assessed at baseline, after a follow-up visit at 6 months, and yearly for 5 years. The primary outcome is chemoprevention informed choice after the follow-up visit. Secondary endpoints include other patient-reported outcomes, such as chemoprevention knowledge, decision conflict and regret, and self-reported chemoprevention usage. Barriers and facilitators to implementing decision support into clinic workflow are assessed through patient and provider interviews at baseline and mid-implementation.

RESULTS/DISCUSSION

With this hybrid effectiveness/implementation study, we seek to evaluate if a multi-level intervention effectively promotes informed decision-making about chemoprevention and provide valuable insights on how the intervention is implemented in U.S.

CLINICAL SETTINGS

TRIAL REGISTRATION

NCT04496739.

Life Events, Barriers to Care, and Outcomes Among Minority Women Experiencing Depression: A Longitudinal, Mixed-Method Examination

ABSTRACT

The long-term course of depression is not well-understood among minority women. We assessed depression trajectory, barriers to depression care, and life difficulties among minority women accessing health and social service programs as part of the Community Partners in Care study. Data include surveys ( N = 339) and interviews ( n = 58) administered at 3-year follow-up with African American and Latina women with improved versus persistent depression. The majority of the sample reported persistent depression (224/339, 66.1%), ≥1 barrier to mental health care (226/339, 72.4%), and multiple life difficulties (mean, 2.7; SD, 2.3). Many barriers to care ( i.e. , related to stigma and care experience, finances, and logistics) and life difficulties ( i.e. , related to finances, trauma, and relationships) were more common among individuals reporting persistent depression. Results suggest the importance of past experiences with depression treatment, ongoing barriers to care, and negative life events as contributors to inequities in depression outcomes experienced by minority women.

Growing a Community-Academic Partnership: Lessons Learned in Forming a Qualitative Interview Team for the Community Partners in Care Study

By engaging, partnering, and building trust with community members, research on vulnerable populations may offer opportunities to improve population health in communities that suffer from health disparities. While the literature on participatory and partnered approaches offers techniques and strategies for forming community-academic partnerships, less information is available about how partnerships can grow and evolve over time. In this article, we describe the expansion of a long-standing partnership that uses principles of community partnered participatory research (CPPR), a variant of community-based participatory research (CBPR). We outline the preparation and executive phases of conducting qualitative interviewing with highly vulnerable study participants who have already been participants in a longitudinal survey. We describe the challenges and concerns at each phase of the research and summarize some lessons learned. To grow and evolve, the partnership must constantly be reaffirmed in the experiences of new members.

Abstract GS5-07: Weight change in postmenopausal women and breast cancer risk in the women's health initiative observational study

Purpose

While obesity is an established breast cancer risk factor, information about the influence of weight loss on breast cancer risk in postmenopausal women is mixed precluding generation of a strong public health message regarding potential benefits of weight loss with respect to cancer risk. Therefore, we evaluated associations between weight change and invasive breast cancer risk in postmenopausal women participating in the Women's Health Initiative (WHI) Observational Study.

Patients and Methods

Postmenopausal women (n=61,335) with no prior breast cancer and normal mammogram who were not underweight (body mass index [BMI] ≥ 18.5 kg/m2), ages 50-79 years at WHI enrollment between 1993 and 1998 at 40 US clinical centers, had body weight and height measured and BMI calculated at the clinical centers at baseline and at year 3. Weight change over 3 years was categorized as: stable (no change ≤ 5%), loss (change ≥ 5%), or gain (change ≥ 5%) with weight lost intentionality determined by self-report response to direct query at year 3. Breast cancers were initially ascertained through annual survey and were centrally confirmed by medical record review. Multi-variable Cox proportional hazards regression models incorporating breast cancer risk factors and baseline BMI were used to evaluate relationships between weight change and breast cancer incidence.

Results

During 11.4 years (mean) of follow-up, 3,061 women developed invasive breast cancer. In multi-variable analyses, compared with women with stable weight (n=41,139), women with weight loss (≥ 5%) (n=8,175) had a significantly lower breast cancer risk (hazard ratio [HR] 0.88 95% confidence interval [CI] 0.78-0.98). Adjustment for mammography did not alter findings (HR 0.88 95% CI 0.78-0.99). There was no significant interaction for breast cancer effect by weight loss intentionality. Women with weight loss ≥ 15% had even lower breast cancer risk (HR 0.63 95% CI 0.45-0.90). While weight gain (≥ 5%) (n=12,021) was not associated with higher overall breast cancer risk, women with weight gain had a significantly higher risk of triple negative breast cancer (HR 1.54 95% CI 1.16-2.05). Weight change association with breast cancer incidence was examined in four subgroups: by tumor subtype (hormone receptor and HER2 status based), baseline BMI (normal, overweight, obese), race/ethnicity, and age group (50, -<70 years). Effects in all subgroups was similar with no evidence of heterogeneity as no interaction term test in these analyses was significant.

Conclusion

Weight loss in postmenopausal women is associated with lower breast cancer risk. These findings suggest that postmenopausal women who lose weight may reduce their breast cancer risk.

Citation Format: Chlebowski RT, Luo J, Anderson GL, Simon M, Barrington W, Reding K, Manson JE, Rohan T, Wactawki-Wende J, Lane D, Strickler H, Mossavar-Rahmani Y, Freudenheim J, Saquib ATN, Stefanick M. Weight change in postmenopausal women and breast cancer risk in the women's health initiative observational study [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr GS5-07.

Continuous Combined Estrogen Plus Progestin and Endometrial Cancer: The Women's Health Initiative Randomized Trial

BACKGROUND

While progestin addition to estrogen mitigates endometrial cancer risk, the magnitude of the effect on incidence, specific endometrial cancer histologies, and endometrial cancer mortality remains unsettled. These issues were assessed by analyses after extended follow-up of the Women's Health Initiative (WHI) randomized clinical trial evaluating continuous combined estrogen plus progestin use.

METHODS

The WHI enrolled 16 608 postmenopausal women into a randomly assigned, double-blind, placebo-controlled trial. Women age 50 to 79 years with intact uteri with normal endometrial biopsy at entry were randomly assigned to once-daily 0.625 mg conjugated equine estrogen plus 2.5mg medroxyprogesterone acetate (n = 8506) as a single pill or matching placebo (n = 8102). Follow-up beyond the original trial completion date required reconsent, obtained from 12 788 (83%) of surviving participants. Analyses were by intent-to-treat. All statistical tests were two-sided.

RESULTS

After 5.6 years' median intervention and 13 years' median cumulative follow-up, there were fewer endometrial cancers in the combined hormone therapy compared with the placebo group (66 vs 95 case patients, yearly incidence, 0.06% vs 0.10%; hazard ratio [HR] = 0.65, 95% confidence interval [CI] = 0.48 to 0.89, P = .007). While there were somewhat fewer endometrial cancers during intervention (25 vs 30, respectively; HR = 0.77, 95% CI = 0.45 to 1.31), the difference became statistically significant postintervention (41 vs 65, respectively; HR = 0.59, 95% CI = 0.40 to 0.88, P = .008), but hazard ratios did not differ between phases (P difference = .46). There was a statistically nonsignificant reduction in deaths from endometrial cancer in the estrogen plus progestin group (5 vs 11 deaths, HR = 0.42, 95% CI = 0.15 to 1.22).

CONCLUSION

In postmenopausal women, continuous combined estrogen plus progestin decreases endometrial cancer incidence.

Of conflicts, conspiracies, red herrings, and black swans

The impact of the findings from the Women's Health Initiative trial of estrogen plus progestin cannot be attributed to any real or imagined conflicts of interest between government, researchers, and journals. Rather, the findings overturned decades of dogma in part promoted by the pharmaceutical industry, and the reaction to these unexpected findings was in direct proportion to their importance in reversing a misguided practice of prescribing the drug for chronic disease prevention. The findings have been widely accepted, as shown by the sustained subsequent reduction in prescriptions. However, conflicts of interest may influence a minority unwilling to accept the findings. The decrease in the use of a drug with an adverse risk profile for prevention of chronic disease is a public good.

Abstract OT3-3-02: Phase IIB randomized double-blind placebo-controlled biomarker modulation study of high dose vitamin D in premenopausal women at high-risk for breast cancer: SWOG S0812

Background: Priorities in breast cancer chemoprevention include developing agents effective against estrogen receptor (ER)-negative breast cancer and validating intermediate biomarkers which correlate with breast cancer risk. Vitamin D is a fat-soluble vitamin which regulates calcium and bone homeostasis, but also has diverse biological effects relevant to breast carcinogenesis. The biologically active form of vitamin D [1,25(OH)D] interacts with the vitamin D receptor (VDR) to modulate cell proliferation, differentiation, apoptosis, and angiogenesis. Epidemiologic data suggests that serum 25(OH)D levels >40-50 ng/ml are associated with a 40-50% reduction in breast cancer risk compared to women with vitamin D deficiency (<20 ng/ml). Given the high prevalence of vitamin D deficiency in the general population, vitamin D3 3000-4000 IU daily would be required to raise 25(OH)D to this putative target level. The central hypothesis of this proposal is that high-dose vitamin D will modulate biomarkers of breast cancer risk.

Trial Design: This trial is a phase IIB, randomized, double-blind, placebo-controlled study of oral vitamin D3 (cholecalciferol) 20,000 IU (2 capsules) weekly for one year in 200 premenopausal women at high-risk for breast cancer. Both groups will be supplemented with a standard dose of vitamin D3 600 IU daily. Participants will undergo a mammogram and optional random core breast biopsy timed within 10 days after the start of their menstrual cycle at baseline and 1 year and blood collections at baseline, 6, and 12 months. Participants will be monitored for toxicity, particularly hypercalcemia and hypercalciuria, every 3 months during the 1-year intervention.

Main Eligibility Criteria: High-risk is defined as a 5-year Gail risk score ≥1.67% or lifetime risk ≥20%, history of atypical hyperplasia, lobular or ductal carcinoma in situ, germline mutations in BRCA1, BRCA2, p53, or PTEN, history of stage I-II breast cancer in remission for >5 years, or baseline mammographic density >50%. Other eligibility criteria include baseline serum 25(OH)D ≤32 ng/ml, normal serum calcium and urine calcium/creatinine ratio, and no history of kidney stones.

Specific Aims: The primary endpoint is change in mammographic density at 12 months compared to baseline between the vitamin D and placebo groups. Secondary exploratory endpoints include breast tissue-based biomarkers (Ki-67, cleaved caspase-3, ER, VDR, and 1α-hydroxylase) and blood-based biomarkers (25(OH)D, 1,25(OH)D, PTH, IGF-1, IGFBP-3, VDR polymorphisms).

Statistical Methods: Power calculations are based on a two-sample comparison of normal deviates, using a 2-sided, 0.05-level test. To be conservative, we assume that 15% will have missing breast density data at 12 months and a 2% difference in mammographic density between intervention and control at 12 months with a the standard deviation for each arm of 4%. With 200 women randomized, the study will have 90% power to detect this difference.

Target Accrual: 200. Sixty-seven patients accrued as of June 2013. Accrual completion expected December 2014.

Contact: Katherine Crew, Columbia University Medical Center, kd59@columbia.edu.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr OT3-3-02.

Health risks and benefits from calcium and vitamin D supplementation: Women's Health Initiative clinical trial and cohort study

SUMMARY

The Women's Health Initiative (WHI) double-blind, placebo-controlled clinical trial randomly assigned 36,282 postmenopausal women in the U.S. to 1,000 mg elemental calcium carbonate plus 400 IU of vitamin D(3) daily or placebo, with average intervention period of 7.0 years. The trial was designed to test whether calcium plus vitamin D supplementation in a population in which the use of these supplements was widespread would reduce hip fracture, and secondarily, total fracture and colorectal cancer.

INTRODUCTION

This study further examines the health benefits and risks of calcium and vitamin D supplementation using WHI data, with emphasis on fractures, cardiovascular disease, cancer, and total mortality.

METHODS

WHI calcium and vitamin D randomized clinical trial (CT) data through the end of the intervention period were further analyzed with emphasis on treatment effects in relation to duration of supplementation, and these data were contrasted and combined with corresponding data from the WHI prospective observational study (OS).

RESULTS

Among women not taking personal calcium or vitamin D supplements at baseline, the hazard ratio [HR] for hip fracture occurrence in the CT following 5 or more years of calcium and vitamin D supplementation versus placebo was 0.62 (95 % confidence interval (CI), 0.38-1.00). In combined analyses of CT and OS data, the corresponding HR was 0.65 (95 % CI, 0.44-0.98). Supplementation effects were not apparent on the risks of myocardial infarction, coronary heart disease, total heart disease, stroke, overall cardiovascular disease, colorectal cancer, or total mortality, while evidence for a reduction in breast cancer risk and total invasive cancer risk among calcium plus vitamin D users was only suggestive.

CONCLUSION

Though based primarily on a subset analysis, long-term use of calcium and vitamin D appears to confer a reduction that may be substantial in the risk of hip fracture among postmenopausal women. Other health benefits and risks of supplementation at doses considered, including an elevation in urinary tract stone formation, appear to be modest and approximately balanced.

Effect of fat content on infection by Listeria monocytogenes in a mouse model

An estimated 2,500 cases of listeriosis occur annually in the United States. Listeriosis is particularly severe among pregnant women and immunocompromised individuals. Little is known regarding the effect of the food matrix on the ability of L. monocytogenes to survive in the gastrointestinal tract and cause systemic infection. Mice were inoculated with various doses of L. monocytogenes in skim milk, Half & Half, or whipping cream to determine whether differences in milk fat content influence the ability of L. monocytogenes to survive passage through the gut and infect the liver or spleen. The number of fecal samples positive for L. monocytogenes increased with increasing doses of L. monocytogenes for all three vehicles. The number of L. monocytogenes cells isolated from liver or spleen of mice dosed with L. monocytogenes was not significantly different among treatment vehicles. Dose-response models revealed that as the dosage of L. monocytogenes was increased in different milk vehicles, the number of L. monocytogenes cells in liver or spleen also increased. Although fat content of food had no dose-dependent effect on L. monocytogenes infection in the murine gastrointestinal tract, we cannot discount the possibility that it may be a factor in L. monocytogenes infections of humans because of differences in the physiology of gastrointestinal tracts of mice and humans.

Intervention approaches against I/R-induced arterial insufficiency in reconstructive surgery

Ischemia and reperfusion in skeletal muscle is unavoidable during many reconstructive surgeries. Typical examples include replantation, transplantation, and free muscle transfer. One important complication during or after surgery is arterial insufficiency or a no-reflow phenomenon. The microcirculation is a primary target of ischemia and reperfusion injury. Vasoconstriction, poor blood flow, and capillary no-reflow, are the prominent features in the microcirculation seen during reperfusion. Currently, extensive efforts have focused on the theory that reactive oxygen species induce endothelial dysfunction in the microcirculation during reperfusion. Some intervention approaches, including ischemic preconditioning, are developing to interfere with or modulate the pathophysiological processes that are set in motion during ischemia and reperfusion.

The initiating factors of late preconditioning in skeletal muscle

PURPOSE

The goal of these studies was to determine the initiating factors for late preconditioning in the microcirculation of skeletal muscle.

MATERIALS AND METHODS

The cremaster muscle of male Sprague-Dawley rats underwent 4 h of ischemia and then 60 min of reperfusion. Ischemic preconditioning (IPC) consisted of 45 min of ischemia but was done 24 h before the 4 h of ischemia. To mimic the effects of IPC in the late phase, adenosine (ADO) or sodium nitroprusside (SNP) was given 24 h before the prolonged ischemia via local intraarterial infusion. To block the effects of IPC in the late phase, 8-sulfophenyl-theophylline (a nonspecific ADO receptor blocker) or N(W)-nitro-l-arginine (a nonselective nitric oxide synthase antagonist) was given prior to IPC. Microvascular response to IPC and pharmacological preconditioning were determined by measuring arteriole diameters and capillary perfusion using intravital microscopy.

RESULTS

Administration of ADO or SNP on day 1 without IPC produced a similar microvascular protection against prolonged ischemia/reperfusion on day 2 as that induced by IPC alone. In contrast, blocking ADO receptors or nitric oxide synthase on day 1 just prior to IPC eliminated the IPC-induced microvascular protection seen on day 2. In addition, inhibition of nitric oxide synthase on day 1 diminished the protection induced by ADO, but blocking ADO receptors on day 1 did not compromise the protection induced by SNP.

CONCLUSION

The results from these studies suggest that up regulation of ADO is the initiating factor with secondary up regulation of nitric oxide in late preconditioning. Both ADO and nitric oxide contribute to initiating microvascular protection in the late phase of IPC.

Assessment of sublethal endpoints for toxicity testing with the nematode Caenorhabditis elegans

Toxicity tests in invertebrates often use sublethal endpoints, which may exhibit different sensitivity for various toxicants. Our objective was to characterize the sensitivity of movement, feeding, growth, and reproduction as endpoints for heavy metal toxicity testing with Caenorhabditis elegans. Growth and feeding were assessed in the same nematode samples used to assess movement and reproduction. Median effective concentrations (EC50s) for 24-h exposures to Pb, Cu, and Cd were determined for movement, feeding, and growth and a 72-h EC50 was derived for reproduction. The order of toxicity was Cu > Pb > Cd for each endpoint, including lethality and movement. There were no differences in sensitivity among endpoints for any metal. When exposed for 4 h at (sublethal) concentrations that were 14 times the 24-h EC50 value, Pb and Cu reduced feeding to the same extent while movement was reduced significantly more by Pb than by Cu. Thus, a difference in sensitivity of endpoints was apparent at 4 h, which was not evident at 24 h. These observations suggest potentially different mechanisms of toxicity for 24- and 4-h tests.

Microcirculatory changes following different temperature washouts in a free flap model

In spite of the extensive experimental work on vascular washout in free flap surgery, an optimal temperature for the washout solution has not been established. This study was designed to determine the effect of the washout solution temperature on the degree to which the microcirculation is cleared of blood. The cremaster muscle flap in the rat was used, in which the microcirculation can be directly viewed and the presence of blood and perfusion parameters within various vessels can be measured during and after washout. Washout was started with a single, high-pressure infusion and continued at 130 mmHg for 15 minutes. The temperature of the washout solution was either 2-3, 20-22, or 35 degrees C. In all three groups, washout cleared the microcirculation almost completely within the first minute. However, we observed that a cold or room temperature washout cleared the microcirculation more completely than a warm washout did. The temperature of the washout solution did not effect post washout capillary perfusion and/or arterial diameters.

Caenorhabditis elegans as an alternative animal species

Caenorhabditis elegans has proven useful in toxicity testing of known toxicants, but its potential for assessing the toxicity of new pharmaceuticals is relatively unexplored. In this study the procedures used in aquatic testing of toxicants were modified to permit testing of small amounts (<40 mg) of gadolinium-based magnetic resonance imaging (MRI) compounds. Five blinded compounds were tested. The toxicity of these compounds determined using C. elegans was compared to existing mammalian test system data (minimum lethal dose [MLD] values for mice). Four of five compounds tested had the same relative sensitivity with C. elegans as with the mouse test system. Testing with C. elegans is efficient and could markedly reduce the cost of screening potentially useful compounds.

Initiation of microvascular protection by nitric oxide in late preconditioning

The authors hypothesized that nitric oxide is induced by a brief period of ischemia/reperfusion (ischemic preconditioning, IPC) on postoperative day (POD) 1, and that this released nitric oxide is responsible for initiating a delayed microvascular protection against a prolonged period of ischemia in skeletal muscle on POD day 2. The cremaster muscle of male Sprague-Dawley rats underwent 4 hr of ischemia, and then 60 min of reperfusion. IPC consisted of 45 min of ischemia but was done 24 hr before the prolonged ischemia. Local intraarterial infusion of sodium nitroprusside (SNP, a donor of nitric oxide) or Nw-nitro-L-arginine (L-NA, a nonselective nitric oxide synthase antagonist) were also given 24 hr before prolonged ischemia. Arteriole diameters and capillary perfusion were measured using intravital microscopy. Four groups were compared: 1) control; 2) IPC; 3) SNP + sham IPC; and 4) L-NA + IPC. Four hours of ischemia followed by reperfusion created a significant vasoconstriction and capillary no-reflow in the microcirculation of cremaster muscles. These alterations were largely prevented by IPC. Local intraarterial infusion of SNP without IPC created a similar microvascular protection to that induced by IPC alone. In contrast, intraarterial infusion of L-NA prior to IPC eliminated the IPC-induced microvascular protection. In conclusion, in late preconditioning, nitric oxide contributes to the initiation of a delayed microvascular protection against prolonged ischemia in skeletal muscle.

Interaction of angiogenesis inhibitor TNP-470 with basic fibroblast growth factor receptors

TNP-470 is a synthetic analogue of fumagillin that acts as a potent angiogenesis inhibitor. Recently, our laboratory demonstrated that systemic administration of TNP-470 (5.0 mg/kg) decreased the rate of cutaneous wound healing by greater than 20%. In this study, we tested the hypothesis that TNP-470 interferes with the wound repair-stimulating action of basic fibroblast growth factor (bFGF) by competing with endogenous bFGF for its binding sites on the receptor protein. The influence of TNP-470 was examined in vitro in a ligand competition assay of high- and low-affinity receptor binding to (125)I-bFGF in NIH/3T3 cells. Results demonstrated that recognition of (125)I-bFGF by low-affinity growth factor binding sites was significantly decreased (P < 0.01) in the presence of TNP-470. However, TNP-470 inhibition of radiolabeled bFGF binding to high-affinity sites was not significantly affected (P = 0.07). In view of recent studies demonstrating that the low-affinity receptors of bFGF were heparan sulfate proteoglycans, we suggest that the influence of TNP-470 on diminished wound healing is due to its direct recognition by these molecules.

Do leukocytes contribute to impaired microvascular tissue perfusion after arterial repair?

Impaired capillary perfusion may result in flap failure. Platelet emboli, polymorphonuclear leukocytes (PMNs), and/or vasospasm have been identified as possible causes. This study investigates the role of PMNs in causing impaired capillary perfusion in a free flap model. PMN concentrations were depleted using antineutrophil serum. The cremaster muscles of 20 Sprague-Dawley rats were isolated on a single neurovascular pedicle and after a simulated technically poor arterial anastomosis upstream and reperfusion, capillary perfusion was measured each hour for 6 hours. Even though the number of PMNs was significantly reduced in the animals treated with antineutrophil serum, capillary perfusion was not changed compared with controls. These results demonstrate that depleting circulating PMNs does not protect capillary perfusion in our model. These findings suggest that reduced capillary perfusion downstream from an anastomotic repair is not mediated by the presence of PMNs in the microcirculation.

Anatomy of the feeding blood vessels of the cremaster muscle in the rat

Since the early seventies over 300 studies have used the cremaster muscle as a flap model, yet little has been reported on the upstream feeding vessels of this muscle. The purpose of this study was to investigate the anatomy of the cranial feeding vessels of the left and right cremaster muscle in Sprague-Dawley rats. An additional aim was to compare these results with the anatomy of the feeding vessels of the cremaster muscle in another strain (Wistar). To permit identification of the cranial feeding vessels, the pedicle was dissected very carefully and thereafter perfused with green dye, which was administered through a cannula placed in the distal femoral artery. In Sprague-Dawley rats it was found that the cremaster muscle in only 30% of the animals received its total blood supply through the superior external pudendal artery. In Wistar rats the same was true in less than 45%. The cremaster muscle of the rest of the animals appeared to receive its blood either in part or in total from the hypogastric trunk. We suggest that the name pudic-epigastric trunk be abandoned.

Ischemia increases the angiogenic potency of basic fibroblast growth factor (FGF-2)

The aim of this study was to investigate the angiogenic response to exogenously administered basic fibroblast growth factor (FGF-2) in normal and ischemic skin, using the hairless mouse ear microcirculatory model. The hairless mouse ear is a well-established model for in vivo studies of skin microcirculation. Using this model, angiogenesis- and angiogenesis-associated changes in the microcirculation can be directly and continuously viewed and quantified in a variety of different experimental settings. To create ischemia in the mouse ear, all but one of the three to four feeding vessels nourishing the ear were ligated 3 days prior to a local subdermal injection of FGF-2 (9.3 + 1-0.5 mm/mm2) or saline into the dorsum of the ears. Angiogenesis was quantified by direct observation, at high magnification, of the injection site where increases in total vessel length (TVL) were measured repeatedly over 18 days following injection. We found a significant (P < 0.01) increase in TVL in normal and ischemic ears injected with FGF-2. Saline injection also induced a significant increase in TVL in ischemic ears. However, the angiogenic response to FGF-2 in ischemic ears was significantly stronger than saline alone in ischemic ears or saline or FGF-2 in normal ears. This response could be used clinically to accelerate angiogenesis and thus increase perfusion in ischemic tissue.

In vitro platelet aggregation studies in microvascular surgery research: a method in the rat model

There is now a growing awareness of the central role of platelet function in microvascular thrombosis. Platelet aggregation studies remain one of the most useful ways of studying platelet function and response to different stimuli. This brief communication highlights some of the main variables that can affect platelet aggregation in rats and emphasizes the existence of important differences in these variables compared with human platelet aggregation.

Platelet-activating factor contributes to postischemic vasospasm

BACKGROUND

The purpose of the present study was to determine if platelet-activating factor is an important mediator that produces vasospasm during reperfusion after ischemia in skeletal muscle.

MATERIALS AND METHODS

A vascular isolated cremaster muscle in male Sprague-Dawley rats was coupled with local intraarterial drug infusion as a model to study microcirculation responses to ischemia/reperfusion injury. Arteriole diameters and capillary perfusion were measured using intravital microscopy. Group 1: platelet-activating factor dose response. Group 2: Effects of a cyclooxygenase inhibitor; indomethacin, and a thromboxane synthetase inhibitor, imidazole, on the response to platelet-activating factor. Group 3: Effects of nitric oxide synthesis inhibitor; N(omega)-nitro-L-arginine methyl ester, on the response to platelet-activating factor. Group 4: Effects of a platelet-activating factor receptor antagonist, CV-3988, indomethacin, and imidazole after 4 h of warm ischemia and reperfusion.

RESULTS

Intraarterial infusion of platelet-activating factor produced a dose-related but mild vasoconstriction. Pretreatment with indomethacin or imidazole resulted in significant vasodilation actually emanating from platelet-activating factor infusion. Nitric oxide inhibition (with N(omega)-nitro-L-arginine methyl ester) enhanced the vasoconstriction produced by platelet-activating factor. Pretreatment with CV-3988, indomethacin, or imidazole significantly attenuated ischemia/reperfusion-induced vasospasm and capillary no-reflow in the cremaster muscles.

CONCLUSIONS

Ischemia/reperfusion-induced vasoconstriction is at least in part mediated by platelet-activating factor and thromboxane A(2).

Individually randomized intervention trials for disease prevention and control

It is argued that randomized, controlled trials should fulfil a critical role in the identification of practical approaches to the prevention and control of chronic diseases. Because of the great public health potential of chemopreventive and behavioural approaches to chronic disease prevention there is need for a major interdisciplinary scientific effort aimed at intervention development. Because of the cost and duration of controlled trials to evaluate specific interventions there is a need for well-conducted feasibility, pilot and intermediate outcome trials, to inform and to justify corresponding full-scale trials having clinical disease outcomes. Compared to therapeutic trials, prevention trials need to have a greater emphasis on overall benefit versus risk assessment. Such trials need to be large enough, and of sufficient duration, to yield powerful tests of key hypotheses, and informative benefit versus risk summary statements. These requirements have a range of implications for intervention trial design, conduct, monitoring and reporting, which are reviewed and discussed. The clinical trial component of the ongoing Women's Health Initiative provides illustration throughout this discussion.

Leukocyte-endothelium interaction in arterioles after ischemia and reperfusion

Leukocyte-endothelium interaction in postcapillary venules plays an important role in reperfusion injury, inflammation, shock, and sepsis. This phenomenon is poorly described in precapillary arterioles. In fact, many researchers have reported no evidence of leukocyte adherence in arterioles whatsoever. Most research has focused on venules of larger rodents, in which observation of the microcirculation, especially arterioles, is limited. We have developed a model which provides a clearer view of these microvessels using the mouse cremaster muscle. This muscle has an approximate thickness of 100 microm allowing images produced by transillumination to be very clear. After vascular isolation, the right cremaster muscle was subjected to 4 h of ischemia, followed by 2 h of reperfusion. The left muscle was not rendered ischemic, thereby allowing it to serve as the animal's own internal control. We observed leukocyte rolling in arterioles in both the ischemic and the nonischemic muscles. Leukocyte sticking was seen in arterioles and venules on both sides, except in control arterioles. The number of rolling and sticking leukocytes on the ischemic side was significantly higher than in controls (P < 0.05) for both arterioles and venules. During the reperfusion period, this number did not change significantly. Transmigration of leukocytes was observed only in venules, but not in arterioles. The number of perfused capillaries was reduced on the ischemic side compared to controls and did not change significantly during the 2 h of reperfusion. Our results demonstrate that leukocyte-endothelium interaction occurs in muscle arterioles of mice. This phenomenon is more pronounced after ischemia and reperfusion, i.e., depends on the extent of tissue insult.

Estimation of the correlation between nutrient intake measures under restricted sampling

Food frequency questionnaires (FFQs) are commonly used to assess dietary intake in epidemiologic research. To evaluate the FFQ reliability, the commonly used approach is to estimate the correlation coefficient between the data given in FFQ and those in food records (for example, 4-day food records [4DFR]) for nutrients of interest. However, in a dietary intervention study, a criterion for eligibility may be to select participants who have baseline FFQ-measured dietary intake of percent energy from fat above a prespecified quantity. Other instruments, such as the 4DFR, may be subsequently administrated only to eligible participants. Under these circumstances, analysis without adjusting for the restricted population will usually lead to biased estimation of correlation coefficients and other parameters of interest. In this paper, we apply likelihood-based and multiple imputation (MI) methods to accommodate such incomplete data obtained as a result of the study design. A simulation study is conducted to examine finite sample performance of various estimators. We note that both the MI estimate and the maximum likelihood (ML) estimate based on a bivariate-normal model are not sensitive to departures from this normality assumption. This led us to investigate robustness properties of the ML estimator analytically. We present some data analyses from a dietary assessment study from the Women's Health Initiative to illustrate the methods.

Traditional criteria for observation of splenic trauma should be challenged

Age less than 55 years, normal Glasgow Coma Score (GCS), and absence of hypotension are traditional criteria for the selection of adult patients with blunt splenic trauma for observation. The objective of this study is to challenge these criteria. Two hundred twelve patients who presented with blunt splenic injury between 1992 and 1997 were identified from the Trauma Registry at our Level I trauma center. The patients were divided into three groups: 100 patients (47%) were observed, 108 (51%) underwent immediate splenorrhaphy or splenectomy, and 4 (2%) failed observation. The three groups were compared by participants' ages, GCSs, and histories of hypotension. No statistical differences were noted between the successfully observed patients and those requiring immediate surgery with respect to these criteria. Of the 4 patients who failed observation, all were younger than 55 years, all had a GCS >12, and all were normotensive. Our findings suggest that traditional criteria used to select patients for splenic trauma observation are not absolute indicators and should be liberalized: patients can be successfully observed despite having criteria that, in the past, would have led to immediate operative intervention.

Late-preconditioning protection is evident in the microcirculation of denervated skeletal muscle

We investigated whether ischemic preconditioning induces microvascular protection in skeletal muscle at the late phase (after 24 hours) when the same muscles are subjected to prolonged warm global ischemia. The cremaster muscle of the male Sprague-Dawley rat underwent vascular isolation and was subjected to 4 hours of ischemia and 60 minutes of reperfusion. Early preconditioning consisted of 45 minutes of ischemia followed by 15 minutes of reperfusion before prolonged ischemia/reperfusion; late preconditioning also consisted of 45 minutes of ischemia but was done 24 hours (24-hour period of reperfusion) before the prolonged ischemia/reperfusion. Arteriole diameters and capillary perfusion were measured with use of intravital microscopy. Four groups were compared: rats that underwent early preconditioning, their controls, rats that underwent late preconditioning, and their controls. Early and late preconditioning significantly attenuated vasospasm and capillary no-reflow compared with the controls for each. Average arteriole diameter was significantly larger in the rats that underwent late preconditioning than in any other rats; it was also significantly larger in the controls for late preconditioning than in those for early preconditioning. We introduce a model of the rat cremaster muscle that has been isolated from its vascular supply as a useful preparation to study the effects of late preconditioning on microcirculation in skeletal muscle. Late preconditioning provided better microvascular protection than did early preconditioning. The mechanism for this preconditioning protection is being investigated because it should provide a means for therapeutic intervention.

Antiphospholipid antibodies from antiphospholipid syndrome patients activate endothelial cells in vitro and in vivo

BACKGROUND

Antiphospholipid (aPL) antibodies are associated with thrombosis in patients diagnosed with antiphospholipid syndrome (APS) and enhance thrombus formation in vivo in mice, but the mechanism of thrombosis by aPL is not completely understood. Although aPL antibodies have been shown to inhibit protein C activation and activate endothelial cells (ECs) in vitro, no study has examined whether these antibodies activate ECs in vivo. Therefore, human affinity-purified aPL (ap aPL) antibodies from APS patients were tested in a mouse model of microcirculation using the cremaster muscle that allows direct microscopic examination of thrombus formation and adhesion of white blood cells (WBCs) to ECs as an indication of EC activation in vivo. Adhesion molecule expression on human umbilical vein endothelial cells (HUVECs) after aPL exposure was performed to confirm EC activation in vitro.

METHODS AND RESULTS

All 6 ap aPL antibodies significantly increased the expression of VCAM-1 (2.3- to 4.4-fold), with one of the antibodies also increasing the expression of E-selectin (1.6-fold) on HUVECs in vitro. In the in vivo experiments, each ap aPL antibody except for 1 preparation increased WBC sticking (mean number of WBCs ranged from 22.7 to 50.6) compared with control (14.4), which correlated with enhanced thrombus formation (mean thrombus size ranged from 1098 to 6476 versus 594 microm2 for control).

CONCLUSIONS

Activation of ECs by aPL antibodies in vivo may create a prothrombotic state on ECs, which may be the first pathophysiological event of thrombosis in APS.

Angiogenesis inhibitor TNP-470 inhibits murine cutaneous wound healing

BACKGROUND

TNP-470 (AGM-1470) is a potent inhibitor of angiogenesis with potential therapeutic applications in neoplastic and angio-proliferative diseases. This study evaluated its effect on cutaneous wound healing in a murine dorsal excisional wound model.

MATERIALS AND METHODS

Full-thickness wounds (1.60 cm2) were created on the dorsum of homozygous/hairless mice (7 to 9 weeks). Wound areas were measured on alternate days for 16 days. Experimental groups consisted of (1) TNP-470 administered in doses of 0.05, 0.5, and 5.0 mg/kg on Days 0, 2, and 4 or Days 0 through 6; (2) TNP-470 (5.0 mg/kg) coadministered with minocycline (4.0 and 10 mg/kg) on Days 0, 2, and 4; and (3) TNP-470 (5.0 mg/kg on Days 0, 2, and 4) coadministered with topical basic fibroblast growth factor (bFGF) 1. 0 microg/wound on Days 0, 1, and 2. Hematoxylin and eosin staining was used to compare experimental and control wounds.

RESULTS

TNP-470 administration significantly decreased wound healing in a dose-dependent manner versus controls (P <.05). The 5.0 mg/kg concentration yielded the greatest effect by maintaining an average wound area 20.4% greater than controls and a marked delay in wound healing on H&E staining. Alternate-day dosing was as effective as consecutive day administration. Minocycline did not augment the wound healing inhibition of TNP-470. Coadministration of TNP-470 and bFGF eliminated any rate-altering effect of TNP-470 upon wound healing and resulted in wound areas similar to controls.

CONCLUSION

Therapy with TNP-470 induces a significant delay in murine cutaneous wound healing. This effect may be exploited for use in situations where wound healing is excessive and debilitating. Topical application of bFGF can overcome TNP-470-induced wound healing inhibition.

An animal model to study microcirculatory changes associated with vascular delay

Vascular delay is a surgical procedure that renders a flap partially ischaemic several days prior to its transfer in order to increase its viability after its transfer. Though much debate exists regarding the actual mechanism of vascular delay, most theories agree that changes in the microcirculation play a key role. In this paper, we describe four experiments that establish the ear of the homozygous (hr/hr) hairless mouse as an effective model for directly viewing and measuring delay-induced changes in microcirculation. In our first experiment, we compared mouse ears that were delayed (n = 18) with ones that were not (control) (n = 13) and showed that vascular delay significantly (P < 0.05) reduced ear flap necrosis. In a second experiment, we delayed mouse ears for 2 (n = 9), 4 (n = 14), 6 (n = 10), 8 (n = 10), 10 (n = 10), 20 (n = 18), 40 (n = 10) and 80 (n = 11) days and found that the reduction in necrosis becomes statistically significant (P < 0.05) over non-delayed controls (n = 12) after a minimum delay period of 6 days. In a third experiment, we delayed mouse ears by ligating only the vein (n = 14), only the artery (n = 11), only the nerve (sympathectomy) (n = 14), and vein, artery and nerve (n = 14) of the main neurovascular pedicle and found significant (P < 0.05) reductions in flap necrosis in all groups compared to nondelayed controls (n = 12). Finally, in a fourth experiment, we measured vessel directionality changes in mouse ears that were delayed for 6 (n = 4), 10 (n = 4), 20 (n = 4), 40 (n = 4) and 80 (n = 4) days, and found that directionality changes became significant (P < 0.05) at 6 days of delay and remained so for all the days studied when compared with non-delayed controls (n = 4).

Activation of K-Cl cotransport by mild warming in guinea pig red cells

Unidirectional, ouabain-insensitive K+ influx rose steeply with warming at temperatures above 37 degreesC in guinea pig erythrocytes incubated in isotonic medium. The only component of ouabain-insensitive K+ influx to show the same steep rise was K-Cl cotransport (Q10 of 10 between 37 and 41 degrees C); Na-K-Cl cotransport remained constant or declined and residual K+ influx in hypertonic medium with ouabain and bumetanide rose only gradually. Similar results were obtained for unidirectional K+ efflux. Thermal activation of K-Cl cotransport-mediated K+ influx was fully dependent on the presence of chloride in the medium; none occurred with nitrate replacing chloride. The increase of K+ influx through K-Cl cotransport from 37 to 41 degrees C was blocked by calyculin A, a phosphatase inhibitor. The Q10 of K-Cl cotransport fully activated by hydroxylamine and hypotonicity was about 2. The time course of K+ entry showed an immediate transition to a higher rate when cells were instantly warmed from 37 to 41 degrees C, but there was a 7-min time lag in returning to a lower rate when cells were cooled from 41 to 37 degrees C. These results indicate that the steepness of the response of K-Cl cotransport to mild warming is due to altered regulation of the transporter. Total unidirectional K+ influx was equal to total unidirectional K+ efflux at 37-45 degrees C, but K+ influx exceeded K+ efflux at 41 degrees C when K-Cl cotransport was inhibited by calyculin or prevented by hypertonic incubation. The net loss of K+ that results from the thermal activation of isosomotic K-Cl cotransport reported here would offset a tendency for cell swelling that could arise with warming through an imbalance of pump and leak for Na+ or for K+.

Evaluation of N,N-diethyl-m-toluamide (DEET) as a topical agent for preventing skin penetration by cercariae of Schistosoma mansoni

The effect of skin application of N,N-diethyl-m-toluamide (DEET) on the penetration and migration behavior of cercariae of Schistosoma mansoni was evaluated in vitro and in vivo in a mouse model. These studies showed that DEET at concentrations of 7.5% or higher was 100% effective in immobilizing and killing cercariae of S. mansoni in vitro. Ultrastructural studies on such DEET-exposed cercariae showed transformative and degenerative changes involving both tegument and deeper parenchymal structures. Fatal tissue lesions were evident as early as 5 min postexposure to DEET, and became more extensive with increasing exposure time. Cutaneous application of DEET (as a pure chemical in isopropanol or as a commercial insect repellent preparation) was more than 99% effective in preventing entry of S. mansoni cercariae into the mouse tail skin. Radiolabeling and tracer studies confirmed that 7.5% DEET applied to the skin prior to infection was highly effective in preventing schistosomular migration to the lungs.

Glucose-induced intestinal hyperemia is mediated by nitric oxide

Glucose-induced absorptive hyperemia of the intestine has been well demonstrated through microsphere blood flow experiments. We have previously demonstrated that glucose, when applied topically to rat ileal epithelium, restores microvascular vessel diameters and blood flow following Escherichia coli bacteremia or hemorrhage/resuscitation. However, the mechanisms of this hyperemia are not completely understood. We hypothesize that nitric oxide is a mediator of the microvascular response to glucose exposure on the rat intestinal epithelium.

METHODS

Male Sprague-Dawley rats, 200-225 g, were monitored for hemodynamic stability with mean arterial blood pressure and heart rate. A 2-cm segment of the terminal ileum with intact neurovascular supply was exposed for intravital videomicroscopy. Intestinal arteriolar diameters (A1D, inflow; and A3D, premucosal arterioles) and microvascular blood flow (A1Q) were measured following topical application of isoosmotic glucose or saline, with or without l-NAME (LN, 100 mM), a competitive inhibitor of nitric oxide synthase. Statistical analysis was performed by ANOVA followed by Tukey-Kramer honestly significant difference test.

RESULTS

All data are expressed as mean percentage changes from baseline +/- standard error of the mean. Hemodynamic variables did not change during the experimental procedure and there were no significant differences among group baselines. Addition of isotonic glucose to the bath solution caused a significant increase in A3D that persisted throughout the experiment (at 30 min, 19.2 +/- 4.2 vs -3.9 +/- 4.5, P < 0.05). This vasodilation was blocked by topical administration of LN (3.1 +/- 2.9, P < 0.05). A1D remained at baseline levels (saline and glucose) or constricted (LN) in all groups. Topical LN also attenuated A1Q in both the saline and glucose groups.

CONCLUSIONS

These data demonstrate that glucose-induced intestinal hyperemia is primarily characterized by premucosal A3 arteriole dilation in this model and that nitric oxide is a mediator of glucose-induced intestinal hyperemia. These findings suggest that either (1) glucose directly causes endothelial nitric oxide production or (2) epithelial cells transduce a vasodilatory signal through vascular endothelial-derived nitric oxide during postprandial intestinal hyperemia.

Inhibition of wound contraction with locally injected lathyrogenic drugs

BACKGROUND

Previous studies using systematically administered lathyrogens to inhibit wound contractures have produced inconsistent results. The purpose of this study was to investigate the effects of lathyrogenic drugs on wound contraction when injected locally.

METHODS

Two symmetrical full-thickness wounds were made on the dorsum of either side of hairless (hr/hr) mice; thus, each animal served as its own control. Animals were divided into groups receiving daily local injections of beta-aminopropionitrile or D-penicillamine, or both beta-aminopropionitrile and D-penicillamine and normal saline vehicle (control side) for 5 or 10 days. The rate of contraction was determined by serial measurements of the surface area of each wound during the treatment period. At the end of the treatment period, the wounds were excised en bloc with the chest wall and prepared for blinded histological analysis. Granulation tissue thickness, number of fibroblasts in granulation tissue per unit area, number of inflammatory cells (neutrophils, lymphocytes, macrophages and mast cells) in subjacent muscle per unit area, and collagen deposition in subjacent muscle were determined.

RESULTS

Wound contraction, granulation tissue thickness, and collagen deposition in subjacent muscle were decreased only in wounds treated with beta-aminopropionitrile plus D-penicillamine. Collagen deposition in subjacent muscle was also decreased in wounds treated with D-penicillamine alone. Neither drug alone nor the combination affected the number of inflammatory cells in subjacent muscle. Body weight was not affected by the experimental procedures.

CONCLUSIONS

The combination of beta-aminopropionitrile and D-penicillamine is potentially useful for inhibiting contracture formation when injected locally.

Vascular delay in skeletal muscle: a model for microcirculatory studies

Dynamic myoplasty is a relatively new use for muscle flaps and has led us to revisit the mechanisms of vascular delay as a means of optimizing blood supply to muscle flaps. Despite the well-documented effectiveness of vascular delay in skin flaps, vascular delay in muscle flaps has not been widely reported. Regardless of the many mechanisms postulated in the literature as contributors to the delay effect in skin, the one element common to all these hypotheses is the importance placed on changes in the microcirculation. Based on this factor, in the present study we developed and validated an animal model in which delay-induced microvascular changes could be measured in skeletal muscle flaps. We used the hairless mouse latissimus dorsi muscle flap because its vascular distribution is similar to that of humans and its thin structure will enable us in future studies to directly view and measure its microvasculature using videomicroscopy. In 12 animals, we found that delay significantly (p < 0.01) reduced necrosis of the distal part of the muscle from 57 +/- 9 percent in nondelayed flaps (n = 7) to 22 +/- 3 percent in delayed (n = 5) flaps. In these studies, we also determined that the hairless mouse latissimus dorsi muscle flap will serve as an excellent model for defining microvascular changes throughout delay.

Blunt carotid artery injuries

BACKGROUND

Blunt carotid artery trauma remains a rare but potentially devastating injury. Early detection and treatment remain the goals of management. Our objective was to identify patients sustaining blunt carotid injuries at a regional trauma center and report on the incidence, demographics, diagnostic workup, management, and outcome.

STUDY DESIGN

A retrospective chart review was performed of patients sustaining blunt carotid artery injury between 1990 and 1996.

RESULTS

Twenty patients were identified during the 7-year period. All patients suffered blunt trauma, with motor vehicle accidents being the most common mechanism, and the internal carotid the most frequently injured vessel. Associated injuries were present in all patients, with head (65%) or chest (65%) injuries being the most common. The combination of head and chest trauma (45%) was found to be associated with a 14-fold increase in the likelihood of carotid injury. Cerebral angiography was diagnostic in all patients and the majority were treated nonoperatively with anticoagulation. Twenty percent of patients were discharged with a normal neurologic exam, while 45% left with a significant neurologic deficit. Overall mortality was 5%.

CONCLUSIONS

Blunt carotid injuries are rare but are associated with significant morbidity and mortality. The combination of craniofacial and chest wounds should raise the index of suspicion for blunt carotid injury. Anticoagulation was associated with the least morbidity.

Effect of low dose aspirin on thrombus formation at arterial and venous microanastomoses and on the tissue microcirculation

In free flap/replantation surgery, failure is usually associated with thrombotic occlusion of a microvascular anastomosis (risk zone I) or, on occasion, flow impairment in the microcirculation of the transferred or replanted tissue (risk zone II). The objective of this study is to describe the effect of low dose aspirin on blood flow at both risk zones in microvascular surgery. Risk zone I: In rat femoral arteries and veins, thrombus formation was measured at the anastomoses using transillumination and videomicroscopy. Forty male Wistar rats were assigned in equal numbers to four groups: either arterial or venous injury with either aspirin (5 mg/kg systemically) or saline treatment. We found that aspirin significantly reduces thrombus formation at the venous anastomosis (p = 0.001). Risk zone II: In the isolated rat cremaster muscle downstream from an arterial anastomosis, we measured capillary perfusion, arteriolar diameters, and the appearance of platelet emboli for 6 hours in the muscle microcirculation. Sixteen male Wistar rats in two equal groups received either aspirin (5 mg/kg systemically) or saline. We found that in aspirin-treated animals, capillary perfusion is significantly (p = 0.002) improved, whereas arteriolar diameters and emboli only slightly increased. In conclusion, low dose aspirin inhibits anastomotic venous thrombosis and improves microcirculatory perfusion in our rat model. These studies provide quantitative data confirming and clarifying the beneficial effects of low dose aspirin in microvascular surgery.

Platelet-derived thromboxane A2 decreases microvascular perfusion after arterial repair

Previous work suggests that cod liver oil helps to protect the microcirculation from the consequence of thromboembolic events. The possibility that altered synthesis of thromboxane A2 accounts for the protective effects seen with cod liver oil was investigated in the present study. This was done using the combined thromboxane A2 synthetase inhibitor and thromboxane A2-prostaglandin H2 receptor blocker R68070 (Ridogrel). A standardized microvascular injury was inflicted on the right iliac artery of the rat to generate emboli. The downstream cremaster muscle was used to visualize the passage of the ensuing emboli and to assess the effects of this arterial injury on capillary perfusion and arteriole diameters. The number of visible emboli was not changed by either cod liver oil diet or Ridogrel administration. However, capillary perfusion was preserved by using cod liver oil (n = 7) and was significantly increased by using Ridogrel (n = 7) in comparison with untreated controls (n = 7) in which capillary perfusion was decreased because of the emboli. The administration of Ridogrel to cod liver oil-treated animals (n = 7) provided no additive benefit. The percentage change in A-2 vessel diameters in cod liver oil-treated (n = 7) animals was no different from the control group (n = 7). Ridogrel (n = 7), on the other hand, produced a significant increase in A-3 vessel (n = 21) diameters, but its effects were comparatively less in the cod liver oil-treated animals (n = 7). The formation of platelet aggregates (emboli) appears relatively independent of thromboxane A2 in the rat. Ridogrel is very effective in protecting the microcirculation, and these effects appear to be mediated by A-3 vasodilatation, which, therefore, is at least partially thromboxane A2-dependent. The positive effects of cod liver oil may be mediated by a mechanism that reduces thromboxane A2 synthesis, but further studies are necessary.

Prefabricated jejunal free-tissue transfer for tracheal reconstruction: an experimental study

Reconstruction of long-segment tracheal defects is a problem for the reconstructive surgeon. Difficulties arise with the use of prosthetic materials because of their propensity for infection and extrusion. Autologous tissue is limited by poor structural characteristics and technical complexity. We propose a simple composite bioprosthesis that, through a process of prefabrication and subsequent neovascularization, may provide a functional tracheal analogue superior to existing forms of reconstruction. Ten rats had composite flaps constructed by combining an isolated, perfused, mucosectomized segment with an outer covering of a ring-reinforced woven Dacron vascular graft. This unit remained in the intraabdominal milieu for 20 days and was then inspected for viability, incorporation of jejunum and graft, flexibility, and tolerance to negative pressure. Seven experimental animals survived the initial phase. The jejunal bioprostheses in all cases tolerated negative pressures to -200 mmHg, rotation of 180 degrees, and flexion to 90 degrees without collapse of the graft segments. Vascular casts and standard histologic examination showed neovascularization of the Dacron graft and dense fibrovascular ingrowth into the interstices of the graft. We conclude that prefabrication utilizing autologous and prosthetic components to create a single axial flap for transfer is a feasible solution to long-segment tracheal reconstruction. Neovascularization permeates the full thickness of the prosthetic component and is accompanied by dense fibrous ingrowth during the delay period. This neotracheal analogue also possesses structural characteristics similar to those of the native trachea and a durable submucosal layer that can support ingrowth of epithelium.

Inhibition of wound contraction with colchicine and D-penicillamine

The effects of locally injected combined colchicine and D-penicillamine on wound contraction were investigated in a murine model. Two full-thickness excisional wounds were made on either side of the back of hairless (hr/hr) mice. A volume of 0.15 ml of colchicine, D-penicillamine, or combined colchicine and D-penicillamine in normal saline vehicle were injected daily into the wound on one side of the animal and 0.15 ml of vehicle alone was injected into the wound on the other side for 5 or 10 days; thus, each animal served as its own control. The surface area of each wound was measured on Days 0, 5, and 10 to determine an index of the rate of wound contraction. At the end of the experimental period (Day 5 or 10), wounds were excised en bloc from euthanized animals for histological studies. The following histological parameters were determined: the thickness of the granulation tissue, the number of fibroblasts in granulation tissue per unit area, and the number of inflammatory cells (neutrophils, lymphocytes, macrophages, mast cells) in subjacent muscle per unit area. Our data showed that after 5 days of treatment, wound contraction was significantly inhibited only in wounds treated with combined colchicine and D-penicillamine. Wound contraction was significantly inhibited even after 10 days of treatment with the combination. Histological studies revealed that although the thickness of the granulation tissue and the number of inflammatory cells in subjacent muscle were decreased by D-penicillamine alone, only combined colchicine and D-penicillamine decreased the thickness of the granulation tissue, fibroblasts in granulation tissue, and inflammatory cells in subjacent muscle. Our data suggests that very low concentrations of colchicine and D-penicillamine when combined and injected locally may be potentially useful in controlling surface scar formation.

Characterization of microvascular vasoconstriction following ischemia/reperfusion in skeletal muscle using videomicroscopy

This study investigated the possible contribution of microvascular vasoconstriction to no-reflow following ischemia/reperfusion in a mouse skeletal muscle model. Using paired cremaster muscles, arterioles of diameter 10-100 microns were directly viewed and measured by the use of an in vivo videomicroscopy before and after a 6-hr period of complete ischemia at 27 degrees C. Following ischemia/reperfusion, feeder and arcading arterioles constricted significantly to 54.5 and 62% of pre-ischemic baseline diameters respectively (P < .05). While the calcium antagonist diltiazem and nitroprusside were both able to reverse arteriolar constriction, endothelium-dependent acetylcholine-induced dilatation was markedly impaired following reperfusion (P < 0.05). Superoxide dismutase did not attenuate the microvascular response, suggesting that the mechanism is likely to be at least partly free radical-independent.

Introduction of new technologies to the medical undergraduate curriculum

The rate at which new educational technologies are introduced is growing at a tremendous pace. This is in large part due to the recommendations of the AAMC Steering Committee on the Evaluation of Medical Education which strongly supported the use of Medical Informatics technologies for education. Some institutions have attempted to implement these technologies; however, a scientific study has not yet been conducted to document their potential benefit. Our attempts to conduct such a study were met with obstacles of resistance from faculty, administration, and students. To overcome these obstacles we have developed a solution which addresses all of the resistance that we encountered. This solution is based upon three premises: 1) adjunct introduction, 2) multicenter studies, and 3) scientific educational benefit analyses.

Endothelin-1 expression in the small intestine during chronic peritonitis

Endothelins (ET) have been demonstrated to mediate intestinal microvascular constriction during acute Escherichia coli bacteremia, however, their role during chronic infection is unknown. The purpose of this study was to determine whether ET-1 is synthesized in the small intestine in a more chronic peritonitis model. ET-1 mRNA levels of the terminal ileum in mice following cecal ligation and puncture (CLP) were compared to sham-operated animals and normal unoperated animals. ET gene expression was analyzed using differential reverse transcriptase chain reaction (RT-PCR) with co-amplification of beta-actin as an internal standard. To assess ET peptide expression, serum and intestinal tissue levels were measured using a specific enzyme immunoassay (ELISA). The pattern of ET-1 gene expression post-CLP with a single puncture of the cecum with a 23 ga. needle demonstrated a 3.6-fold increase at 8 h, and a return to sham levels by 24 h (374 +/- 64% at 8 h, p < .05, 128 +/- 13%). An increase of mRNA levels at 24 h post-CLP was observed with a double puncture with an 18 ga. needle (230 +/- 36%, p < .05) accompanied by an increase in serum ET levels (270 +/- 31%, p < .05) and higher tissue ET levels. These data indicate a time-dependent response of ET-1 gene expression in the terminal ileum post-CLP which is related to severity of infection.

Can varying flow velocity across an arterial anastomosis prevent thromboembolic injury?

In this study, simulated "poor" repairs applied to transverse incisions in the iliac arteries of 40 rats were the basis for comparing the effect of variations in blood flow on thromboembolism. Using vital microscopy and digital image processing, we performed 2 experiments. In the first experiment (n = 20), the reduction of post-repair blood flow by approximately 50% resulted in an 83% reduction in the total number of emboli appearing in the microcirculation of the cremaster muscle distal to the repair. In the second experiment (n = 20), the same reduction in blood flow typically resulted in larger repair-site thrombi which required significantly more time to grow to their maximum size. We conclude that reducing pedicle artery blood flow to approximately half in our rat model during reperfusion can protect the downstream microcirculation from embolic injury without increasing the incidence of thrombotic occlusion.

Comparison of the effects of commonly used wound agents on epithelialization and neovascularization

BACKGROUND

The primary effect sought with most topical wound therapy is antimicrobial. Topical wound agents are thought to promote normal healing by protecting the wound from infection. In this study, we examined the effect of six commonly used topical wound agents (bacitracin, sodium hypochlorite, silver nitrate, silver sulfadiazine, mafenide acetate, and povidone-iodine) on epithelialization and neovascularization in noninfected wounds. For this study, a new wound model was used in which direct visualization and quantification of wound epithelialization and neovascularization were carried out throughout the entire healing process.

STUDY DESIGN

We measured the effect which 500 U per g of bacitracin, 0.25 percent of sodium hypochlorite, 0.5 percent silver nitrate, 1 percent silver sulfadiazine, 8.5 percent mafenide acetate, and 10 percent povodione-iodine had on the rate of wound epithelialization and neovascularization. The agents were applied topically to 99 circular full-thickness wounds (2.25 mm diameter, 0.125 mm depth) created on the dorsum of male hairless mouse ears. This model enabled us to visualize and measure directly wound epithelialization and neovascularization repeatedly throughout healing, using intravital video microscopy and computerized digitized planimetry.

RESULTS

Control wounds and wounds treated with silver sulfadiazine (n = 18) and mafenide acetate (n = 14) epithelialized in 7.2 +/- 0.7, 7.1 +/- 0.3, and 7.3 +/- 0.3 days, respectively. This was significantly (p < 0.01) faster than the wounds treated with povidone-iodine (n = 10), sodium hypochlorite, (n = 8), and bacitracin (n = 13). Wounds treated with povidone-iodine epithelialized the slowest (11.8 +/- 0.55 days). Wound neovascularization was completed most rapidly in the groups treated with povidone-iodine and silver sulfadiazine (15.0 +/- 0.4 and 15.3 +/- 0.7 days, respectively). This was significantly (p < 0.05) faster than wounds treated with silver nitrate (n = 15), which neovascularized in 18.4 +/- 0.56 days. One-half of the wounds treated with sodium hypochlorite (eight of 16) did not epithelialize or neovascularize.

CONCLUSIONS

The various antimicrobial agents studied in our in vivo model affect wound epithelialization and neovascularization differently. These effects on these two very important aspects of healing should be taken into consideration when indicating a specific agent for treatment of different types of wounds.

Mammography screening: how important is cost as a barrier to use?

OBJECTIVES

Recent legislation will improve insurance coverage for screening mammography and effectively lower its cost to many women. Although cost has been cited as a barrier to use, evidence of the magnitude of its effect on use is limited.

METHODS

Mammography use in the past 2 years among women aged 50 to 75 residing in four suburban or rural counties in Washington State was estimated from 1989 survey data. Logistic regression analysis was used to estimate the odds ratio of mammography use as a function of economic and other variables. Within a residential area, averages were used to measure the market price of mammography and the time cost to obtain a mammogram.

RESULTS

Use was lower among women who faced a higher net price or who preferred to obtain a mammogram during weekend or evening hours and higher among women with higher incomes. Visiting no doctor regularly and smoking were predictors of failure to use mammography.

CONCLUSION

The effects of economic variables on mammography use are important and stable across subsets of the population, but they are modest in size.

Microcirculatory consequences of microvascular surgery

Although free tissue transfer success has been greatly improved by developments in operating microscopes, microsutures, microinstruments, and technique, free flap and replant failure remain a significant problem under certain adverse circumstances. The nature of these failures is often multifactorial and remains poorly understood. A greater understanding of the processes involved would provide the potential for greater pharmacological control of any adverse conditions prevailing and would thus offer the prospect of more effective adjunctive therapy in the presence of such adverse conditions. Research endeavors in this area have been hindered by the absence of good research models. The isolated rat cremaster muscle model is a recently developed model that simulates the conditions of free tissue transfer. Using this model, both thrombus formation and numerous microcirculatory parameters can be measured. The microcirculatory parameters studied to date include the formation of thromboembolism, capillary perfusion, vessel diameters, red blood cell velocity, leukocyte-endothelium interaction, and microvascular leakage. The isolated rat cremaster muscle model addresses many of the shortcomings of earlier research models and offers the promise of answering at least some of the many unanswered questions relating to free flap and replant failure.

Direct visualization and measurements of wound neovascularization: application in microsurgery research

Neovascularization or angiogenesis is an essential yet poorly understood component of the healing process. In wound healing research, there is a lack of models enabling quantitative and continuous measurements of wound neovascularization. The hairless mouse ear wound model permits quantitative measurements of wound epithelialization and neovascularization continuously throughout the healing process. On the ears of male homozygous (hr/hr) hairless mice, standardized circular full thickness dermal wounds are produced; then, using vital microscopy, these two processes are directly viewed and measured at day 0 and every third day thereafter until these are complete. This model system and its application to clinically relevant situations are reviewed.

Direct visualization and measurement of microsurgically induced thromboembolism

A common cause of free flap and replant failure is thrombotic occlusion of the anastomosed pedicle vessel(s). Clinical observations and subsequent experimental studies showed that platelet emboli generated at the arterial anastomosis caused significant alterations in the downstream microcirculation. To study both the thrombogenic arterial (anastomosis) site and the downstream microcirculation, we developed an animal model (the isolated rat cremaster) in which we could directly view and quantitatively analyze thrombus formation and the appearance of emboli in the downstream microcirculation. Using this model we studied the effect that reducing blood flow across the arterial anastomotic site had on thrombus formation at the anastomotic site and the appearance of emboli in the downstream microcirculation. In 40 male Sprague-Dawley rats we found that reducing blood flow velocity to approximately half of normal during reperfusion nearly eliminated emboli appearing in the downstream microcirculation compared with controls, 43.9 +/- 31.5 vs. 259.5 +/- 117.8 emboli, respectively. We also found that the same low flow had no effect on thrombus size at the pedicle artery injury site yet significantly decreased the rate at which thrombus formation occurred (time to maximum thrombus size; low flow = 25.3 +/- 8 minutes, normal flow = 6.6 +/- 3 minutes). From these studies we conclude that reducing pedicle artery blood flow in our rat model during reperfusion can protect the down-stream microcirculation from platelet emboli-induced injury; however, the same reduction in flow does not affect thrombus formation in the pedicle artery. Further studies using direct observation/measurement techniques are needed for a better understanding of the mechanisms regulating free flap and replant failure.