Is Sentinel Lymph Node Biopsy Reliable After Recent Oncoplastic Breast Reduction?

An oncoplastic breast reduction may disrupt normal lymphatic drainage and make subsequent identification of the sentinel lymph nodes (SLNs) unreliable. There are little data on the success rate of sentinel lymph node biopsy (SLNB) after recent oncoplastic breast reduction, and there is no agreement on whether SLNB should be done at the time of the partial mastectomy and reduction for ductal carcinoma in situ (DCIS). The primary goals of this study were to evaluate the identification rate of SLNB after recent oncoplastic or functional breast reduction and to examine recurrence rates in this setting. Results reveal SLNB is feasible in this setting. At least one SLN was found in all patients, and there were no recurrences with an average follow-up of 34 months.

Closed-Incision and Surrounding Soft Tissue Negative Pressure Dressings in Post-Mastectomy Pre-Pectoral Direct-to-Implant Breast Reconstruction: A Pilot Study.

Background: Closed-incision and surrounding soft tissue negative pressure therapy (cistNPT) is theorized to decrease infection, reduce tissue edema, and promote healing of the mastectomy skin flap. We report our early experience with this dressing in pre-pectoral direct-to-implant (pDTI) breast reconstruction. Methods: We retrospectively reviewed all patients who underwent post-mastectomy pDTI breast reconstruction with cistNPT between July 2019 and February 2020. All reconstructions utilized smooth round silicone gel implants and human acellular dermal matrix. Results: Thirty-five female patients underwent 58 mastectomies. Mean age and body mass index were 49.9 years and 28.9 kg/m2, respectively. Eleven (31.4%) patients had neoadjuvant chemotherapy. The mean sternal notch-to-nipple distance was 27.0 cm. The median specimen weight was 483 g, while the median implant volume was 495 cc. The mean implant-to-specimen ratio was 1.4 for nipple-sparing, 1.1 for skin-sparing, and 0.7 for skin-reducing mastectomy. Total drain volume was 483.1 cc from each breast. Post-operative complications included seroma (5.2%), peri-incisional necrosis (8.6%), and superficial skin epidermolysis (13.8%). There were no cases of surgical site infection, dehiscence, or hematoma. Rate of return to the operative room was 3.4%. Mean follow-up was 90 days. Conclusions: In our series of pDTI breast reconstructions with cistNPT, no patients experienced hematoma, dehiscence, or infection complications. Rates of seroma, skin necrosis requiring operative debridement, and total drain volumes were lower than those reported in literature.

Contexte: La thérapie par pression négative des incisions fermées et des tissus mous environnants (cistNPT) doit théoriquement diminuer l'infection, réduire l'œdème tissulaire et faciliter la guérison du lambeau cutané de mastectomie. Nous fournissons notre première expérience avec ce pansement de reconstruction mammaire prépectorale directe à l'implant (pDTI). Méthodes: Nous avons revu rétrospectivement toutes les patientes ayant subi une reconstruction mammaire pDTI post mastectomie entre juillet 2019 et février 2020. Toutes les reconstructions ont utilisé des implants en gel de silicone lisses et ronds avec une matrice dermique acellulaire humaine. Résultats: Trente-cinq femmes ont subi 58 mastectomies. L'âge moyen était de 49,9 ans et l'IMC moyen de 28,9 kg/m2. Onze patientes (31,4 %) recevaient une chimiothérapie néoadjuvante. La distance moyenne du sommet du manubrium sternal au mamelon était de 27,0 cm. Le poids médian de l'échantillon était de 483 g tandis que le volume médian de l'implant était de 495 cc. Le rapport moyen implant/échantillon était de 1,4 pour la préservation du mamelon, 1,1 pour la préservation de la peau et de 0,7 pour la mastectomie de réduction cutanée. Le volume total de drainage de chaque sein a été de 483,1 cc. Les complications postopératoires ont été, notamment, un sérome (5,2 %), une nécrose péri-incision (8,6 %) et une épidermolyse superficielle de la peau (13,8 %). Il n'y a pas eu de cas d'infection du site chirurgical, de déhiscence ou d'hématome. Le taux de reprise chirurgicale a été de 3,4 %. Le suivi moyen a été de 90 jours. Conclusions: Dans notre série de reconstructions du sein par pDTI, aucune patiente n'a eu d'hématome, de déhiscence ou de complication infectieuse. Les taux de sérome, de nécrose cutanée nécessitant un débridement chirurgical et les volumes totaux de drainage étaient inférieurs aux chiffres publiés.

Outcomes of Margin Reexcision after Oncoplastic Breast Reduction.

Tissue rearrangement after an oncoplastic breast reduction may complicate identification of margins during reexcision. Little is known about outcomes of reoperation in this setting. Methods: This is a single-institution, retrospective analysis of outcomes of margin reexcisions after lumpectomy with concurrent oncoplastic Wise-pattern reduction from 2015 to 2020. Outcomes assessed were the rate of successful breast conservation, in-breast recurrence, wound issues or complications, effect on cosmesis, and delay to onset of adjuvant therapy. Results: From 2015 to 2020, 649 patients underwent lumpectomy with oncoplastic Wise-pattern reduction. Forty-seven patients (7.2%) had greater than or equal to one positive margin(s); of these, 28 went directly to mastectomy, and 19 underwent margin reexcision. Residual disease was found in seven of 19 patients (37%) at reexcision. The rate of successful breast-conserving therapy was 95% with a mean follow-up of 31 months. There was one (5%) in-breast recurrence (invasive ductal carcinoma [IDC] occurring 30 months after the original operation); this patient had a mastectomy for treatment of her recurrence. The overall complication rate was 37%. Radiation was administered to 18 patients (95%), and two patients (11%) had delay of radiation past 6 weeks due to wound complications. Of the 14 patients with photographs available, 12 of 14 patients (86%) were blindly assessed to have equivalent or better cosmesis after margin reexcision (versus initial lumpectomy). Conclusion: Margin reexcision after oncoplastic breast reduction with Wise-pattern is feasible and effective, and can be done without compromising the initial cosmetic results.

Hospital-Based Same-Day Compared to Overnight-Stay Mastectomy: An American College of Surgeons National Surgical Quality Improvement Program Analysis.

Background: Enhanced Recovery after Surgery for mastectomy has resulted in increased use of outpatient same-day mastectomy (SDM). Whether SDM leads to increased readmissions or reoperations is not well documented. This study examines national data to compare outcomes of SDM to an overnight stay. Methods: We analyzed the American College of Surgeons National Surgical Quality Improvement Program Participant Use Data File from 2016 to 2018 for all mastectomy cases. Cases with a length of stay (LOS) >1 day were excluded. Cases were then categorized into 2 LOS cohorts: SDM vs 1-day LOS. Results: A total of 22,642 cases (80.8% 1-day LOS vs 19.2% SDM) were identified for the final analysis. Patients in the 1-day LOS group were more likely to be older (57.9 vs 54.0 years, P<0.01), be female (98.0% vs 79.8%, P<0.01), and have greater comorbidity (38.1% vs 30.7% American Society of Anesthesiologists classification 3 or 4, P<0.01) compared to the SDM group. Multivariate analysis demonstrated no difference in risk for 30-day wound complications between the SDM and 1-day LOS groups. The risks for 30-day medical complications (1.60 odds ratio [OR], 95% CI 1.06-2.42, P=0.02), reoperations (1.46 OR, 95% CI 1.17-1.81, P<0.01), and readmissions (1.60 OR, 95% CI 1.25-2.05, P<0.01) were higher in the 1-day LOS group. Even after excluding patients undergoing reoperation on the day of surgery, the risk for reoperations (2.3% vs 3.3%, P<0.01) remained higher in the 1-day LOS group. Characteristics associated with 1-day LOS were hypertension, steroid use, diabetes, dyspnea, dependent functional status, bilateral procedures, and breast reconstruction. Conclusion: We demonstrate that SDM is a safe procedure, with no increase in risk for 30-day postoperative complications. Appropriate patients should be offered SDM.

Rinse But Don't Repeat: Single Application V.A.C. VERAFLO Salvages Infected Breast Prostheses.

INTRODUCTION: Existing salvage protocols for infected breast prostheses using negative pressure wound therapy with instillation and dwell (NPWTi-d) require multiple returns to the operating room and prolonged length of stay. We present our expedited salvage protocol and discuss outcomes and associated costs savings. METHODS: Using a retrospective review, we identified 25 consecutive patients (27 breasts) with peri-prosthetic breast infection. Nine patients (10 breasts) underwent removal of infected breast prostheses followed by autologous or staged implant-based reconstruction. Sixteen patients (17 breasts) underwent our single application salvage protocol. A cost analysis was performed comparing the two groups, and an economic model was used to project the cost savings associated with using single application NPWTi-d protocol. RESULTS: Fifteen of the 16 patients (94%) who underwent single application NPWTi-d had successful implant salvage. Average duration of NPWTi-d was 2 days, 7 hours, and average length of stay was 4.43 days. Compared to control, patients who received the single application protocol required significantly fewer hospitalizations and office visits. A total savings of $58,275 could have been achieved by using the single application NPWTi-d protocol in the patients who did not undergo NPWTi-d. CONCLUSIONS: Single application of NPWTi-d is a simple, safe, and cost-effective technique for salvage of breast prostheses, with 94% success rate, even in immunocompromised patients and severe infection. Compared to previous protocols, ours requires fewer trips to the operating room, shorter length of stay, and more permanent implants placed during salvage. Our protocol is also associated with fewer office visits and fewer returns to the operating room.

Two-stage Prosthetic Prepectoral Breast Reconstruction: Comparing Tissue Expansion with Carbon Dioxide and Saline.

BACKGROUND: The AeroForm tissue expander is a carbon dioxide-filled breast tissue expander that allows gradual, needle-free expansion using a hand-held remote controller. This study evaluates 2-stage, prepectoral tissue expander-to-implant breast reconstruction with the carbon-dioxide tissue expanders and compares the outcomes to our recent experience with saline tissue expanders. METHODS: This was a retrospective study of consecutive patients from a single institution. The subjects consisted of women who underwent mastectomy and either immediate or delayed breast reconstruction with AeroForm or saline tissue expanders. Outcomes encompassed postoperative complications including mastectomy flap necrosis, infection requiring readmission and/or intravenous antibiotics, capsular contracture, hematoma, seroma, skin dehiscence, extrusion, premature explant, and loss of communication with the device (AeroForm) or rupture of the device (saline). RESULTS: This study evaluated 115 patients with 185 breast reconstructions. Of the 185 breast reconstructions, 74 (40%) utilized AeroForm tissue expanders and 111 (60%) utilized traditional saline tissue expanders. Treatment was successful in 100% and 94% in the AeroForm and saline groups, respectively (P = 0.025). The incidence of adverse events was greater in the saline group (45.9% versus 32.4%). Surgical-site infection occurred more commonly in the saline group (5.4% versus 0%). Full-thickness skin necrosis occurred at a significantly higher rate in the saline cohort as compared with AeroForm (5.4% versus 0%). CONCLUSIONS: The use of AeroForm tissue expanders offers notable advantages for breast reconstruction. This device when employed in the prepectoral space may be associated with reduced infection rates and decreased utilization of healthcare and patient resources.

Porcine acellular dermal matrix (PADM) vascularises after exposure in open necrotic wounds seen after complex hernia repair.

Biological alternatives to synthetic meshes are increasingly utilised in complex abdominal wall reconstruction. There is a lack of evidence demonstrating that non-cross-linked porcine acellular dermal matrix vascularizes and integrates with human tissue in suboptimal wound conditions. We aimed to evaluate these properties in Strattice™ (Life Cell Inc., Branchburg, NJ) following ventral hernia repair. A retrospective review of patients with high-risk ventral hernia repair utilising Strattice™ as an onlay after open component separation was conducted. Patients with postoperative wound exploration and exposure of the onlay were included in this review. One patient underwent punch biopsy for histological analysis. Eleven patients with wound complications necessitating postoperative debridement and exposure of Strattice™ onlay were identified. The onlay was partially debrided in two cases, and one case required complete excision. Vascularisation was clinically evident in 10 of 11 cases (91%) as demonstrated by the presence of granulation tissue and/or the ability to support a skin graft. Histological analysis of one onlay 3 months postoperatively showed neovascularisation and collagen remodelling with minimal inflammatory response. Strattice™ demonstrated resistance to rejection, ability to undergo vascularisation and incorporation into host tissues in sub-optimal wound conditions following ventral hernia repair.

Massive localized lymphedema revisited: a quickly rising complication of the obesity epidemic.

Massive localized lymphedema (MLL) is a rising and potentially fatal complication of the obesity epidemic. Described as a benign lymphoproliferative overgrowth of obese patients, MLL is a form of secondary lymphedema, caused by the obstruction of lymphatic flow, with characteristic clinical and histological presentation. Patients have a large mass with classic skin changes often accompanied by lymphatic weeping that require complex reconstruction. Although oftentimes benign, if left untreated, MLL can progress to angiosarcoma, further supporting the need for more research into MLL and its sequelae. We present a unique case of MLL of the mons pubis in a 52-year-old man with a body mass index of 75.7 kg/m. The literature was comprehensively reviewed with a total of 65 cases of MLL being described, 9 of which resulted in angiosarcoma (10.3% of all cases), 6 of which resulted in death (9.2% of all cases). We found a female predominance of 1.24 to 1, an average weight of 183 kg, and a 48.5% majority of cases in the thigh.

Utility of indocyanine green fluorescence lymphography in identifying the source of persistent groin lymphorrhea.

SUMMARY: Surgical manipulation of the groin can result in lymphatic injury in a significant number of patients leading to poor wound healing or infectious complications. Surgical repair of lymphatic injury is greatly aided by the precise and prompt intraoperative localization of the injured lymphatic vessels. We assessed and identified lymphatic leaks in 2 cases of surgical wound lymphorrhea occurring after instrumentation of the groin using laser-assisted indocyanine green lymphography paired with isosulfan blue injection. Both cases healed without complication, and no lymphatic leak recurrence was observed during postoperative follow-up. Laser-assisted indocyanine green lymphography is a useful adjunct in the management of lymphatic leaks after surgery of the groin and may have potential for prophylactic evaluation of high-risk groin wounds.

Identification of novel NOTCH1 mutations: increasing our knowledge of the NOTCH signaling pathway.

BACKGROUND: Alterations in the NOTCH1 signaling pathway are found in about 60% of pediatric T-ALL, but its impact on prognosis remains unclear. PROCEDURE: We extended the previously published CoALL cohort (n = 74) to a larger cohort (n = 127) and additionally included 38 Argentine patients from ALL IC-BFM to potentially identify novel mutations and decipher a stronger discriminatory effect on the genotype/phenotype relationship with regard to early treatment response and long-term outcome. RESULTS: Overall, 101 out of 165 (61.2%) T-ALL samples revealed at least one NOTCH1 mutation, 28 of whom had combined NOTCH1 and FBXW7 mutations. Eight T-ALL samples (4.8%) exclusively revealed FBXW7 mutations. Fifty-six T-ALL (33.9%) exhibited a wild-type configuration of either gene. Four novel NOTCH1 mutations were identified localized in the C-terminal PEST domain, in the rarely affected LNR repeat domain and in the ankyrin domain. Novel LNR mutations may contribute to a better understanding of the structure of the NOTCH1 negative regulatory region (NRR) and the R1946 mutation in the ankyrin domain may represent an unusual loss-of-function mutation. CONCLUSIONS: Overall, NOTCH1 pathway mutations did not affect the relapse rate and outcome of the extended T-ALL cohort uniformly treated according to CoALL protocols, although NOTCH1 mutations were associated with good response to induction therapy (P = 0.009). Individually, HD and PEST domain mutations might exert distinct functional effects on cellular homeostasis under treatment NOTCH1 pathway activity with prognostic implications.

Efficiency of different selection strategies against boar taint in pigs.

The breeding scheme of a Swiss sire line was modeled to compare different target traits and information sources for selection against boar taint. The impact of selection against boar taint on production traits was assessed for different economic weights of boar taint compounds. Genetic gain and breeding costs were evaluated using ZPlan+, a software based on selection index theory, gene flow method and economic modeling. Scenario I reflected the currently practiced breeding strategy as a reference scenario without selection against boar taint. Scenario II incorporated selection against the chemical compounds of boar taint, androstenone (AND), skatole (SKA) and indole (IND) with economic weights of -2.74, -1.69 and -0.99 Euro per unit of the log transformed trait, respectively. As information sources, biopsy-based performance testing of live boars (BPT) was compared with genomic selection (GS) and a combination of both. Scenario III included selection against the subjectively assessed human nose score (HNS) of boar taint. Information sources were either station testing of full and half sibs of the selection candidate or GS against HNS of boar taint compounds. In scenario I, annual genetic gain of log-transformed AND (SKA; IND) was 0.06 (0.09; 0.02) Euro, which was because of favorable genetic correlations with lean meat percentage and meat surface. In scenario II, genetic gain increased to 0.28 (0.20; 0.09) Euro per year when conducting BPT. Compared with BPT, genetic gain was smaller with GS. A combination of BPT and GS only marginally increased annual genetic gain, whereas variable costs per selection candidate augmented from 230 Euro (BPT) to 330 Euro (GS) or 380 Euro (both). The potential of GS was found to be higher when selecting against HNS, which has a low heritability. Annual genetic gain from GS was higher than from station testing of 4 full sibs and 76 half sibs with one or two measurements. The most effective strategy to reduce HNS was selecting against chemical compounds by conducting BPT. Because of heritabilities higher than 0.45 for AND, SKA and IND and high genetic correlations to HNS, the (correlated) response in units of the trait could be increased by 62% compared with scenario III with GS and even by 79% compared with scenario III, with station testing of siblings with two measurements. Increasing the economic weights of boar taint compounds amplified negative effects on average daily gain, drip loss and intramuscular fat percentage.

Incisional negative-pressure wound therapy versus conventional dressings following abdominal wall reconstruction: a comparative study.

BACKGROUND: Improvements in surgical techniques have allowed us to achieve primary closure in a high percentage of large abdominal hernia repairs. However, postoperative wound complications remain common. The benefits of negative-pressure wound therapy (NPWT) in the management of open abdominal wounds are well described in the literature. Our study investigates the effects of incisional NPWT after primary closure of the abdominal wall. METHODS: A retrospective chart review was performed for the period between September 2008 and May 2011 to analyze the outcomes of patients treated postoperatively with incisional NPWT versus conventional dry gauze dressings. Patient information collected included history of abdominal surgeries, smoking status, and body mass index. Postoperative complications were analyzed using χ exact test and logistic regression analysis. RESULTS: Fifty-six patients were included in this study; of them, 23 were treated with incisional NPWT, whereas 33 received conventional dressings. The rates of overall wound complications in groups I and II were 22% and 63.6%, respectively (P = 0.020). The rates of skin dehiscence were 9% and 39%, respectively (P = 0.014). Both outcomes achieved statistical significance. Rates of infection, skin and fat necrosis, seroma, and hernia recurrence were 4%, 9%, 0%, and 4% for group I and 6%, 18%, 12%, 9% for group II, respectively. CONCLUSIONS: This study suggests that incisional NPWT following abdominal wall reconstruction significantly improves rates of wound complication and skin dehiscence when compared with conventional dressings. Prospective, randomized, controlled studies are needed to further characterize the potential benefits of this therapy on wound healing after abdominal wall reconstruction.

A performance test for boar taint compounds in live boars.

Genetically reducing boar taint using low-taint lines is considered the most sustainable and economic long-term alternative to surgical castration of male pigs. Owing to the high heritability of the main boar taint components (androstenone, skatole and indole), breeding is an excellent tool for reducing the number of tainted carcasses. To incorporate boar taint into breeding programmes, standardized performance testing is required. The objective of this study was to develop and formally present a performance test for the main boar taint compounds on live breeding candidates. First, a standardized performance test for boar taint was established. A biopsy device was developed to extract small tissue samples (200 to 300 mg) from breeding candidates. Quantification of boar taint components from these small samples using specialized chemical extraction methods proved accurate and repeatable (r = 0.938). Following establishment of the method, biopsy samples of 516 live boars (100 to 130 kg live weight) were collected in the second step. Various mixed linear models were tested for each boar taint compound; models were ranked in terms of their information content. Pedigree information of 2245 ancestors of biopsied animals was included, and genetic parameters were estimated using univariate and multivariate models. Androstenone (in µg/g liquid fat (LF): mean = 0.578, σ = 0.527), skatole (in µg/g LF: mean = 0.033, σ = 0.002) and indole (in µg/g LF: mean = 0.032, σ = 0.002) levels obtained by biopsy were plausible. Heritability estimates for androstenone calculated with univariate (0.453) and multivariate (0.452) analyses were comparable to those in the literature. Heritabilities for skatole (0.495) and indole (0.550) were higher than that for androstenone. Genetic and phenotypic correlations were similar to those published previously. Our results show that data on boar taint compounds from small adipose samples obtained by biopsy provide similar genetic parameters as that described in the literature for larger samples and are therefore a reliable performance test for boar taint in live breeding candidates.

Effects of systemic tadalafil on skin flap survival in rats.

OBJECTIVE: Phosphodiesterase-5 inhibitors, used to increase penile blood flow in erectile dysfunction patients, have recently been postulated to increase blood flow and flap survival in cutaneous flaps based on random blood supply. This study aims to investigate the phosphodiesterase-5 inhibitor tadalafil, administered orally, on random flap survival. METHODS: Modified McFarlane flaps measuring 8 cm × 2.5 cm were raised on the backs of 37 male Sprague-Dawley rats. Rats received were divided into a control group, a low-dose group (10 mg/kg tadalafil), and a high-dose group (20 mg/kg tadalafil). Treatment doses were administered once preoperatively and every 24 hours postoperatively for a total of 7 doses. On postoperative day 7 and 14, the area of flap survival was calculated and compared. RESULTS: All rats survived and thrived throughout the experimental period. Control group rats showed an average flap survival of 77% ± 11% at 7 days and 77% ± 9% at 14 days. Low-dose-group rats showed an average flap survival of 82% ± 10% at 7 days (P=0.21), and 81% ± 12% at 14 days (P=0.41). High-dose group rats showed an average flap survival of 81% ± 11% at 7 days (P = 0.45) and 80% ± 12% at 14 days (P = 0.53). Statistical analysis was performed using the Mann-Whitney test. CONCLUSIONS: Our results indicate a trend toward increased random-pattern flap survival with both high- and low-dose oral tadalafil in a rat model. Because this trend did not achieve statistical significance, further studies are warranted.

An effective technique for salvage of cardiac-related devices.

Millions of patients require implantable cardiac devices for management of cardiac dysrhythmias. These devices are susceptible to erosion, exposure, or infection and plastic surgeons are consulted when salvage is required. As of yet, an anterior muscle-splitting approach to effectively and safely relocate the device into the subpectoral position has not been described in the plastic surgery literature. The authors retrospectively reviewed the charts of 7 patients who required repositioning of cardiac devices. Indications for repositioning included exposure, erosion, infection, hematoma at the time of primary placement (3), and one cosmetic revision. All patients were treated with subpectoral repositioning of the device into the subpectoral space via an anterior muscle-splitting approach. Six of 7 patients (86%) achieved successful long-term repositioning in the subpectoral position without recurrent exposure or hematoma and with good cosmetic results. One patient who had a prior history of multiple failed device placements required reoperation due to recurrent infection. The anterior muscle-splitting technique proposed by the authors for defibrillator or pacemaker salvage is a feasible technique with promising results. Plastic surgeons should be aware of this simple and effective approach.

Significant predictors of complications after sternal wound reconstruction: a 21-year experience.

BACKGROUND: We sought to identify patient comorbidities that predict complications after tissue flap sternal reconstruction. METHODS: A retrospective study, December 1989 to December 2010, analyzed numerous comorbidities, including diabetes mellitus (DM), hypertension (HTN), coronary artery disease, congestive heart failure (CHF), and renal insufficiency, as independent risk factors for postoperative complications. Pearson χ2 test, Fisher exact test, 2-sample t test, and median-unbiased estimation were used for data analysis. Significance was P≤0.05. RESULTS: In all, 106 patients received 161 sternal tissue flap repairs. Nineteen patients (18%) required reoperation because of complications, including recurrent wound infection, tissue necrosis, wound dehiscence, mediastinitis, and hematoma formation. Our analysis found DM, HTN, and CHF as significant predictors of complications after sternal reconstruction (P=0.014, 0.012, and 0.006). CONCLUSIONS: Results suggest DM, HTN, and CHF may contribute to complications after tissue flap repair of sternal wounds, possibly through impaired perfusion and healing of repairs.

Parent-of-origin effects cause genetic variation in pig performance traits.

In order to assess the relative importance of genomic imprinting for the genetic variation of traits economically relevant for pork production, a data set containing 21 209 records from Large White pigs was analysed. A total of 33 traits for growth, carcass composition and meat quality were investigated. All traits were recorded between 1997 and 2006 at a test station in Switzerland and the pedigree included 15 747 ancestors. A model with two genetic effects for each animal was applied: the first corresponds to a paternal and the second to a maternal expression pattern of imprinted genes. The imprinting variance was estimated as the sum of both corresponding genetic variances per animal minus twice the covariance. The null hypothesis of no imprinting was tested by a restricted maximum likelihood ratio test with two degrees of freedom. Genomic imprinting significantly contributed to the genetic variance of 19 traits. The proportion of the total additive genetic variance that could be attributed to genomic imprinting was of the order between 5% and 19%.

The use of acellular dermal matrix to prevent capsule formation around implants in a primate model.

BACKGROUND: Implant-based breast reconstruction is a popular option after mastectomy, but capsular contracture may detract from long-term outcomes. The authors have observed that breast implants covered with acellular dermal matrix (AlloDerm) are less likely to develop a capsule in the area where the implant is in direct contact with the acellular matrix. The authors tested this observation experimentally by comparing capsular formation around implants in the presence and absence of AlloDerm in primates. METHODS: Eight smooth-surfaced tissue expanders were implanted into eight African green monkeys. In four experimental animals, a sheet of AlloDerm was draped over the tissue expander so as to cover the implant. Four control animals underwent placement of a tissue expander only. Animals were killed after 10 weeks and specimens underwent histologic and immunohistochemical analysis. RESULTS: Hematoxylin and eosin staining of control specimens revealed the presence of a distinct layer of wavy, parallel arrays of collagen fibers consistent with capsule formation. Immunostaining identified abundant myofibroblasts, a profibrotic cell found in breast capsules. In the AlloDerm-covered specimens, no capsule layer was visible, and specimens stained weakly for myofibroblasts. The difference in myofibroblast staining intensity was statistically significant. CONCLUSIONS: The use of AlloDerm to partially enclose implants effectively prevented formation of a capsule in areas where AlloDerm contacted the implant at 10 weeks. Long-term studies will be required to determine whether this is a durable result that can be reproduced in humans.

Acellular dermal matrix compared with synthetic implant material for repair of ventral hernia in the setting of peri-operative Staphylococcus aureus implant contamination: a rabbit model.

BACKGROUND: Implant infection is a common clinical complication of abdominal hernia repair. Our objectives were to determine if acellular dermal matrix (ADM) grafts resisted Staphylococcus aureus infection better (as measured by ability to reduce or clear bacterial counts) than synthetic (polytetrafluoroethylene [PTFE]) mesh when used in abdominal wall reconstruction, and to determine whether vascularization of the implant occurred. We hypothesized that the ability of the ADM grafts to vascularize and allow cellular ingrowth would allow the immune system to clear the infection better in these animals. METHODS: In New Zealand White rabbits (average weight, 3.0 kg), a full-thickness 3 x 3 cm(2) abdominal defect was created, then repaired with an interpositional implant (ADM, n = 62; PTFE, n = 57). Before skin closure, the epidermal surface of each implant was inoculated with 1 mL of S. aureus at various concentrations (10(4) colony-forming units [CFU]/mL, n = 82; 10(6) CFU/mL, n = 27; 10(9) CFU/mL, n = 10), and the rabbits were harvested at either day 7 or day 21. RESULTS: At day 7, ADM grafts inoculated with 10(4) CFU had lower counts or no bacteria (p = 0.006), fewer adhesions (p = 0.005), and fewer abscesses (p = 0.008) than PTFE grafts. By day 21, more ADM (n = 12) than PTFE (n = 0) grafts were free of bacteria (p = 0.002). Fewer rabbits with ADM grafts formed abscesses (13 vs. 19; p = 0.03). When evaluating the 7- and 21-day 10(4) CFU groups combined, a total of 15 rabbits with ADM cleared the bacteria completely vs. none of those with PTFE grafts (p < 0.001). There was no significant difference in bacterial counts or wound complications at days 7 or 21 between PTFE and ADM implants when inoculated with 10(6) CFU. All rabbits inoculated with 10(9) CFU died of sepsis within 48 h. Herniation did not occur in any of the animals. CONCLUSIONS: Our study demonstrates that ADM resists surgical site infection caused by S. aureus in an animal model without compromising the ventral hernia repair. This ability of ADM grafts to perform well in the setting of infection is most likely attributable to their capacity to vascularize and aid clearance of bacteria.