Impact of Gabapentin on Postoperative Hypotension in Enhanced Recovery after Surgery Protocols for Microvascular Breast Reconstruction.

Background: Enhanced recovery after surgery (ERAS) protocols have been associated with hypotensive episodes after autologous breast reconstruction. Gabapentin (Gaba), a nonopioid analgesic used in ERAS, has been shown to attenuate postoperative hemodynamic responses. This study assesses ERAS's impact, with and without Gaba, on postoperative hypotension after microvascular breast reconstruction. Methods: Three cohorts were studied: traditional pathway, ERAS + Gaba, and ERAS no-Gaba. We evaluated length of stay, inpatient narcotic use [morphine milligram equivalents (MME)], mean systolic blood pressure, hypotension incidence, and complications. The traditional cohort was retrospectively reviewed, whereas the ERAS groups were enrolled prospectively after the initiation of the protocol in April 2019 (inclusive of Gaba until October 2022). Results: In total, 441 patients were analyzed. The three cohorts, in the order mentioned above, were similar in age and bilateral reconstruction rates (57% versus 61% versus 60%). The ERAS cohorts, both with and without Gaba, had shorter stays (P < 0.01). Inpatient MME was significantly less in the ERAS + Gaba cohort than the traditional or ERAS no-Gaba cohorts (medians: 112 versus 178 versus 158 MME, P < 0.01). ERAS + Gaba significantly increased postoperative hypotensive events on postoperative day (POD) 1 and 2, with notable reduction after Gaba removal (P < 0.05). Across PODs 0-2, mean systolic blood pressure was highest in the traditional cohort, followed by ERAS no-Gaba, then the ERAS + Gaba cohort (P < 0.05). Complication rates were similar across all cohorts. Conclusions: Postmicrovascular breast reconstruction, ERAS + Gaba reduced overall inpatient narcotic usage, but increased hypotension incidence. Gaba removal from the ERAS protocol reduced postoperative hypotension incidence while maintaining similar stay lengths and complication rates.

Same-Day Discharge for Immediate Breast Reconstruction: A National Surgical Quality Improvement Program Study.

BACKGROUND: Patients undergoing immediate breast reconstruction with tissue expanders are frequently admitted after surgery for monitoring and pain control, which introduces additional costs and risks of nosocomial infection. Same-day discharge could conserve resources, mitigate risk, and return patients home for faster recovery. The authors used large data sets to investigate the safety of same-day discharge after mastectomy with immediate postoperative expander placement. METHODS: A retrospective review was performed of patients in the National Surgical Quality Improvement Program database who underwent breast reconstruction using tissue expanders between 2005 and 2019. Patients were grouped based on date of discharge. Demographic information, medical comorbidities, and outcomes were recorded. Statistical analysis was performed to determine efficacy of same-day discharge and identify factors that predict safety. RESULTS: Of the 14,387 included patients, 10% were discharged the same day, 70% on postoperative day 1, and 20% later than postoperative day 1. The most common complications were infection, reoperation, and readmission, which trended upward with length of stay (6.4% versus 9.3% versus 16.8%), but were statistically equivalent between same-day and next-day discharge. The complication rate for later-day discharge was statistically higher. Patients discharged later had significantly more comorbidities than same or next-day discharge counterparts. Predictors of complications included hypertension, smoking, diabetes, and obesity. CONCLUSIONS: Patients undergoing mastectomy with immediate tissue expander reconstruction are usually admitted overnight. However, same-day discharge was demonstrated to have an equivalent risk of perioperative complications as next-day discharge. For the otherwise healthy patient, going home the day of surgery is a safe and cost-effective option, although the decision should be made based on the individual patient. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

Enhanced Recovery after Surgery Protocol Decreases Length of Stay and Postoperative Narcotic Use in Microvascular Breast Reconstruction.

Background: Enhanced recovery after surgery (ERAS) protocols have demonstrated efficacy following microvascular breast reconstruction. This study assesses the impact of an ERAS protocol following microvascular breast reconstruction at a high-volume center. Methods: The ERAS protocol introduced preoperative counseling, multimodal analgesia, early diet resumption, and early mobilization to our microvascular breast reconstruction procedures. Data, including length of stay, body mass index, inpatient narcotic use, outpatient narcotic prescriptions, inpatient pain scores, and complications, were prospectively collected for all patients undergoing microvascular breast reconstruction between April 2019 and July 2021. Traditional pathway patients who underwent reconstruction immediately before ERAS implementation were retrospectively reviewed as controls. Results: The study included 200 patients, 99 in traditional versus 101 in ERAS. Groups were similar in body mass index, age (median age: traditional, 54.0 versus ERAS, 50.0) and bilateral reconstruction rates (59.6% versus 61.4%). ERAS patients had significantly shorter lengths of stay, with 96.0% being discharged by postoperative day (POD) 3, and 88.9% of the traditional cohort were discharged on POD 4 (P < 0.0001). Inpatient milligram morphine equivalents (MMEs) were smaller by 54.3% in the ERAS cohort (median MME: 154.2 versus 70.4, P < 0.0001). Additionally, ERAS patients were prescribed significantly fewer narcotics upon discharge (median MME: 337.5 versus 150.0, P < 0.0001). ERAS had a lower pain average on POD 0-3; however, this finding was not statistically significant. Conclusion: Implementing an ERAS protocol at a high-volume microvascular breast reconstruction center reduced length of stay and postoperative narcotic usage, without increasing pain or perioperative complications.

Sarcopenia Best Predicts Complications in Free Flap Breast Reconstruction.

Breast reconstruction remains a major component of the plastic surgeon's repertoire, especially free-flap breast reconstruction (FFBR), though this is a high-risk surgery in which patient selection is paramount. Preoperative predictors of complication remain mixed in their utility. We sought to determine whether the sarcopenia score, a validated measure of physiologic health, outperforms the body mass index (BMI) and modified frailty index (mFI) in terms of predicting outcomes. Methods: All patients with at least 6-months follow-up and imaging of the abdomen who underwent FFBR from 2013 to 2022 were included in this study. Appropriate preoperative and postoperative data were included, and sarcopenia scores were extracted from imaging. Complications were defined as any unexpected outcome that required a return to the operating room or readmission. Statistical analysis and regression were performed. Results: In total, 299 patients were included. Patients were split into groups, based on sarcopenia scores. Patients with lower sarcopenia had significantly more complications than those with higher scores. BMI and mFI both did not correlate with complication rates. Sarcopenia was the only independent predictor of complication severity when other factors were controlled for in a multivariate regression model. Conclusions: Sarcopenia correlates with the presence of severe complications in patients who undergo FFBR in a stronger fashion to BMI and the mFI. Thus, sarcopenia should be considered in the preoperative evaluation in patients undergoing FFBR.

Anaphylactic Reaction to Lymphazurin 1% during Breast Reconstruction Surgery: An Uncommon but Serious Complication.

Lymphazurin 1% (isosulfan blue dye) is the most frequently used blue dye in the United States, and it is commonly used for sentinel node biopsy in breast cancer patients. Although cases of allergic reaction to lymphazurin have been reported in the general surgery literature, to our knowledge, no cases of an adverse reaction to isosulfan blue have been reported in the plastic surgery literature. We describe a case of an intraoperative biphasic anaphylactic reaction to isosulfan blue in a female patient undergoing bilateral mastectomy and immediate bilateral DIEP breast reconstruction. The severity of her anaphylactic reaction required that we stop flap dissection and abort the reconstruction. Although an allergic reaction is uncommon, recognizing the signs of an acute hypersensitivity reaction is critical to good outcomes in these situations. Given the volume of combined breast oncologic and breast reconstruction surgeries and the increasing number of vascularized lymph node transfer and lymphovenous anastomosis performed annually, it is essential for the plastic surgeon to be cognizant of this rare hypersensitivity reaction.

Increasing Appropriate BRCA1/2 Mutation Testing: The Role of Family History Documentation and Genetic Counseling in a Multidisciplinary Clinic.

BACKGROUND: Findings show that 5-10 % of women with a diagnosis of breast cancer (BCa) have actionable genetic mutations. The National Comprehensive Cancer Network guidelines for testing to detect BRCA1/2 mutations include personal history (PH) variables such as age of 45 years or younger and a family history (FH) variables. Rates of FH documentation and overall rates of appropriate referral for genetic testing are low, ranging from about 30 to 60 %. The authors hypothesized that an upfront FH documentation and inclusion of a genetics counselor in a multidisciplinary clinic (MDC) setting would increase rates of appropriate referral for genetic testing. METHODS: The study enrolled 609 consecutive women with non-metastatic BCa seen in consultation between June 2012 and December 2015 at a multidisciplinary clinic. Rates of FH documentation and referral for genetic testing to detect BRCA1/2 mutations were assessed before and after inclusion of a genetic counselor in the MDC. RESULTS: The rates of FH documentation and appropriate referral were 100 and 89 %, respectively. Half (50 %) of the patients had only FH-based indications for testing. All the patients with PH-based indications were referred. The inclusion of a genetic counselor significantly increased appropriate referral rates among those with only FH-based indications (62 vs. 92 %) and overall (80 vs. 96 %) (p < 0.0001 for both). Among the 12 % of the patients with actionable mutations, 60 % were 45 years of age or younger, whereas 30 % had only FH-based testing indications. CONCLUSIONS: This report shows substantially higher FH documentation and appropriate genetic testing rates than prior reports. Many patients with indications for genetic testing may have only FH-based indications for testing, and this subset may account for the sizable proportion of patients with newly diagnosed BCa who have actionable mutations.

Comparison of immediate postoperative pain in implant-based breast reconstructions.

BACKGROUND: Implant-based techniques represent the most common form of breast reconstruction. However, substantial postoperative pain has been associated with implant-based breast reconstruction. OBJECTIVE: The objective of this study is to evaluate immediate postoperative pain in implant-based breast reconstruction. METHODS: We reviewed 378 patients who underwent implant-based reconstruction between January 2004 and December 2012. Each patient's visual analog scale (VAS) score, pain medication, and patient-controlled analgesia (PCA) attempts were used to assess in-hospital postoperative pain. We evaluated timing of reconstruction post mastectomy, tissue expander (TE) designed fill volume, TE initial fill volume, and single-stage immediate implant (II) versus TE reconstruction. RESULTS: No significant differences in pain parameters were noted between the immediate and delayed postmastectomy reconstruction cohorts. TEs with larger (>300 cc) designed volumes required significantly more narcotic use (p = 0.02) and PCA attempts (p < 0.01). Narcotic use was higher in the larger (>250-cc) TE initial fill group starting on postoperative day 2, but overall differences in VAS score and PCA attempts were not significant. Morphine equivalence (p < 0.01) and non-opioid oral analgesic use (average p = 0.03) of the TE cohort were significantly higher than those of the II cohort. CONCLUSION: Patients undergoing TE-based implant reconstruction show greater analgesic use than those with single-stage II-based reconstruction. This may indicate a higher immediate postoperative pain in TE procedures than in II procedures. Furthermore, higher initial fill and designed volume of TE require more morphine equivalence postoperatively. These findings may warrant further preoperative discussion for better pain management and patient satisfaction.

Comparison of postoperative pain control in autologous abdominal free flap versus implant-based breast reconstructions.

BACKGROUND: Women who undergo mastectomy and breast reconstruction are shown to express more pain than those who undergo mastectomy alone. The authors evaluated postoperative pain outcomes following breast reconstruction. METHODS: Patients undergoing primary implant-based (n = 1038) or flap-based (n = 837) reconstructions from 2004 to 2012 at the University of California, Los Angeles, were evaluated. Postoperative pain was measured using the visual analogue scale, total narcotic use, and number of patient-controlled analgesia attempts. Narcotic dosage was standardized to morphine equivalents per kilogram. The authors modeled postoperative narcotic use, patient-controlled analgesia attempts, and visual analogue scale scores over time using spline graphs for comparison between the two reconstruction methods. RESULTS: Both total narcotic use and patient-controlled analgesia attempts were higher in the implant-based group throughout the immediate postoperative period. Implant-based reconstruction patients had significantly higher visual analogue scale scores (p < 0.0001) and total narcotic use (p < 0.0001) through postoperative day 3 compared with autologous tissue-based reconstruction patients. When controlling for reconstruction method, bilateral procedures were more painful (visual analogue scale score and patient-controlled analgesia attempts, both p < 0.001). When controlling for laterality, unilateral implant-based and autologous reconstructions had comparable visual analogue scale scores (p = 0.38) and patient-controlled analgesia attempts. However, unilateral implant-based procedures required more narcotic use than unilateral autologous tissue-based procedures (p = 0.0012). CONCLUSION: Although commonly perceived as a less distressing operation, implant-based breast reconstruction may be more painful during the immediate postoperative hospitalization than abdominally based free tissue transfer. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, III.

The effect of prior abdominal surgery on abdominally based free flaps in breast reconstruction.

BACKGROUND: The abdomen has long remained the preferred donor site in breast reconstruction. Over time, the flap has evolved to limit morbidity with reduced muscular harvest. Previous abdominal operations, however, may limit the ability to perform a muscle- or fascia-sparing flap. The purpose of this study was to evaluate outcomes in women who had prior abdominal operations and underwent abdominally based autologous breast reconstruction. METHODS: All patients who underwent abdominally based breast free flap reconstruction between 2004 and 2009 were reviewed. A study group of patients with previous open abdominal surgery were compared to patients with no prior abdominal surgery. Patient demographics, operative details, and flap and donor-site complications were analyzed. RESULTS: A total of 539 patients underwent abdominally based breast free flap reconstruction. The study group consisted of 268 patients (341 flaps) and the control group consisted of 271 patients (351 flaps). Prior abdominal surgery led to greater muscular harvest, as 19.9 percent in the study group versus 12.0 percent required muscle-sparing 1-type harvest (p < 0.01). Both groups presented similar overall complications, with the exception of lower partial flap loss and increased wound healing complications in the study group (p < 0.05). Abdominal wall laxity became less frequent with increasing number of prior abdominal operations. CONCLUSIONS: Abdominally based flaps for breast reconstruction, including muscle-sparing 3 (deep inferior epigastric perforator) flaps, can be performed safely in patients with prior abdominal surgery. These patients should be informed, however, of an increased chance of muscular harvest and wound healing complications. CLINICAL QUESTION/LEVEL OF EVIDENCE: Risk, III.

Colony size optimisation in colony-based laser imaging for microbial source tracking.

The colony-based laser scatter imaging provides a convincing solution to microbial source tracking. The optical scattering patterns of bacterial colonies are tightly correlated to the corresponding growth patterns. This relationship is manifested as the development of optical scattering patterns with the increment of colony size. An investigation was conducted into this relationship and the optimal range of colony size for improving the accuracy of microbial source tracking technique. All the bacterial samples from five host species were cultivated under the same conditions. The optical scattering patterns were recorded for the average colony diameter from 0.1 mm to 1.5 mm, using a bench top laser imaging system. Gabor wavelet was utilised to encode image signatures. Fuzzy-C-means was employed to cluster the colony patterns from the same host species. The experimental results demonstrate that the optimal range of the colony diameters is 0.8-1.0 mm. The corresponding identification rate of microbial source tracking is >80%.

Recent trends in resident career choices after plastic surgery training.

The purpose of this study is to determine the initial career choice of plastic surgery residents after completion of training during the last five years and to identify any factors that may influence choice of career path. Demographic data were obtained from graduates of Accreditation Council for Graduate Medical Education (ACGME)-accredited US plastic surgery residency programs between the years of 2005 and 2010. The type of practice and pursuit of fellowship were recorded for each graduate. Sex, age at graduation, marital status, dependents, advanced degrees, previous research, type of training program, primary residency, and length of plastic surgery training were also documented. Comparison of outcomes between the two plastic surgery training pathways (integrated vs independent) was analyzed. Data were collected for 424 graduates from 37 different training programs. Of these programs, 11% were from the West coast, 32% from Midwest, 33% from East coast, and 24% from the South. Seventy-nine percent of residents were male, mean age at graduation was 35 (2.89) years. Forty-nine percent of residents were married, 30% had one or more dependents, 6% had advanced degrees, and 18% had previous research experience. Fifty-eight percent of graduates were from independent programs. Forty-eight percent of residents pursued private practice immediately after graduation, 8% pursued academic practice, 41% pursued specialty fellowships, and 3% had military commitments. Most of the residents chose to pursue private practice on completion of residency. Independent residents were significantly more likely to pursue private practice immediately compared to integrated/combined residents. No other factors were significant for practice choice.

Algorithms for modeling structural changes in human chromosomes.

Human cytogenetics is the study of chromosomes (typically at mitotic metaphase). The study of chromosomes has recently become integrated with molecular biology and genomics. Thus, it is an important part of genetics education. However, it is time consuming to train students and clinical technologists to recognize patterns of G-banded human chromosomes because of the dynamic nature of G-band resolutions in different metaphase spreads. Moreover, there are limited resources to obtain the images of abnormal chromosomes. We present in this paper an advanced version of computer based interactive tutorial program capable of simulating chromosome abnormalities, altering chromosome shapes, and manipulating G-band resolutions for human cytogenetic seduction. By simulating chromosomes using digital image processing and pattern recognition, the versatile software, together with various strategies such as website links and dialogs, will provide students with a virtual learning environment for self-practicing and testing, thus transforming the traditionally dry and ineffective approach into an exciting and efficient learning process.

Cost analysis of near-infrared spectroscopy tissue oximetry for monitoring autologous free tissue breast reconstruction.

Free flap monitoring typically requires specialized nursing that can increase medical costs. This study uses near-infrared spectroscopy (NIRS) tissue oximetry to monitor free tissue breast reconstruction. We hypothesize this practice will reduce medical costs by eliminating the need for specialized nursing. From August 2006 to January 2010, women undergoing unilateral free tissue breast reconstruction were enrolled and admitted postoperatively to either the surgical intensive care unit (ICU) or floor. Each underwent continuous monitoring using NIRS tissue oximetry and intermittent clinical examination with surface Doppler ultrasonography. Patient demographics, comorbidities, perioperative details, and financial data were recorded. There were 50 patients studied, all with abdominal-based flaps (25 per group). There were no statistically significant differences in patient demographics, comorbidities, mean flap weight, ischemia time, or length of stay between the ICU and floor groups. Four flaps had vascular complications, all detected by NIRS tissue oximetry. Comparison of hospital costs showed an average reduction of $1937 per patient when monitored on the surgical floor (P = 0.036). NIRS tissue oximetry is a sensitive and reliable monitoring tool, eliminating the need for specialized nursing care. The effect is decreased cost structure and increased hospital contribution margin for autologous free tissue breast reconstruction.

Early gene response of human brain microvascular endothelial cells to Listeria monocytogenes infection.

The gene expression of human brain microvascular endothelial cells (HBMEC) in response to 4 h of infection by Listeria monocytogenes was analyzed. Four hours after infection, the expression of 456 genes of HBMEC had changed (p < 0.05). We noted that many active genes were involved in the formyl-methionyl-leucyl-phenylalanine pathway in infected HBMEC. In the upregulated genes, mRNA levels of interleukin-8 and interleukin-15 in infected cells increased according to microarray and real-time reverse transcription - PCR analyses. Since both cytokines are regarded as potent chemotactic factors, the results suggest that HBMEC are capable of recruiting cells of innate and adaptive immune responses during early L. monocytogenes infection.

Perforator flaps in breast reconstruction.

Patients are well informed and seek autogenous breast reconstruction. The motivating factors include a preference for autologous tissue reconstruction and the complementary improvement in body contour, safety concerns surrounding implants, and implant-related complications in the setting of previous radiation therapy. In this article a variety of perforator flaps from donor sites that include the trunk (thoracodorsal artery perforator and intercostal artery perforator), abdomen (deep inferior epigastric artery perforator and superficial inferior epigastric artery), and buttock (superior gluteal artery perforator and inferior gluteal artery perforator) are described. Flaps from the trunk can be pedicled for partial breast reconstruction, and free flaps from the other donor sites can completely restore a natural-looking breast. The information obtained from preoperative CT and MRI can direct the surgeon toward the most successful operative plan. However, the decision as to which flap may be most appropriate for an individual patient is complex. This article reviews pertinent surgical anatomy, preoperative planning, intraoperative decision making in flap elevation, and reported outcomes.

Inclusion of mesh in donor-site repair of free TRAM and muscle-sparing free TRAM flaps yields rates of abdominal complications comparable to those of DIEP flap reconstruction.

BACKGROUND: Pedicled and free transverse rectus abdominis musculocutaneous (TRAM) flaps remain popular for autologous breast reconstruction, but the incidence of abdominal donor-site bulge and hernia is significantly greater when compared with deep inferior epigastric artery perforator (DIEP) flap reconstruction. Mesh repair after muscle harvest, however, may reduce the complication rate to that observed with perforator flaps alone. METHODS: A retrospective review of all free flap breast reconstructions at the University of California, Los Angeles Medical Center from 2002 to 2007 was performed. Abdominal bulge and hernia were noted for patients undergoing free TRAM and muscle-sparing free TRAM flap reconstructions and were compared with those observed following DIEP flap reconstructions. RESULTS: A total of 275 free TRAM plus muscle-sparing free TRAM flaps and 200 DIEP flaps were performed. Among patients with free and muscle-sparing free TRAM flaps, 11.3 percent were found to have postoperative abdominal bulge or hernia. Only 3.5 percent of DIEP flap patients had abdominal complications. Incorporating mesh into the rectus fascia repair significantly reduced the abdominal complications reported to 5.1 percent. Of the 86 free and muscle-sparing free TRAM flaps that were bilateral, 12.8 percent had hernias/bulges. Use of mesh with bilateral free and muscle-sparing free TRAM flaps reduced the complication rate to 3.7 percent. CONCLUSIONS: Incorporating mesh into rectus fascia repair in free and muscle-sparing free TRAM flap cases significantly reduces the rate of postoperative abdominal complications to levels equivalent to those for DIEP flap reconstructions. The authors advocate deciding intraoperatively between DIEP and muscle-sparing free TRAM flap dissections based on ease of dissection and whichever offers optimal safety and flap perfusion. Routine use of mesh in donor-site repair will decrease postoperative abdominal morbidity in unilateral and bilateral cases.

A comprehensive cytogenetics tutorial program, encompassing changeable G-band resolutions.

Chromosome analysis is a basic science with medical implication. Karyotyping is a procedure to study an individual's chromosome make-up. It is time consuming to train students and clinical technologists to recognize patterns of G-banded chromosomes because of the dynamic nature of G-band resolutions in different metaphase spreads. High resolution G-bands are desirable because they provide detailed information for structural analysis. However, it is challenging to identify chromosomes at higher resolution levels even for many cytogenetics technologists. In response to the need for training students to identify human chromosomes at variable G-band resolutions, we present in this paper an advanced version of virtual reality (VR)-based interactive karyotyping program capable of manipulating G-band resolutions for human cytogenetics education. The program can generate different metaphase spreads ranging from short and well separate chromosomes at low G-band resolutions to long, curved, and overlapped chromosomes at high G-band resolutions. Other features include a scoring system, helping strategies, and the progress reports. The traditional "cut and paste" karyotyping method for chromosome separation is incorporated in the software. This method is compared with the "simple clicking" method which is based on an edge detection technique for outlining each chromosome. The comprehensive program is suitable for in-depth training of advanced students.

Laser imaging for rapid Microbial Source Tracking.

DNA fingerprinting, PCR and other genomic technologies have recently been used to determine sources of fecal bacteria in waterways. Here, we report on the development of a simple and automated optical method for potential use in Microbial Source Tracking (MST) of E. coli. The method employs laser imaging of bacterial colonies and high-resolution optical scattering image analysis for information extraction and classification. Cross validation is used to statistically evaluate the robustness of the classifiers. The entire image analysis procedure can be fully automated, making this a potentially useful tool for future MST studies.

Interactive computer program for learning genetic principles of segregation and independent assortment through meiosis.

Teaching fundamental principles of genetics such as segregation and independent assortment of genes could be challenging for high school and college biology instructors. Students without thorough knowledge in meiosis often end up of frustration and failure in genetics courses. Although all textbooks and laboratory manuals have excellent graphic demonstrations and photographs of meiotic process, students may not always master the concept due to the lack of hands-on exercise. In response to the need for an effective lab exercise to understand the segregation of allelic genes and the independent assortment of the unlinked genes, we developed an interactive program for students to manually manipulate chromosome models and visualize each major step of meiosis so that these two genetic principles can be thoroughly understood.

Consistent deregulation of gene expression between human and murine MLL rearrangement leukemias.

Important biological and pathologic properties are often conserved across species. Although several mouse leukemia models have been well established, the genes deregulated in both human and murine leukemia cells have not been studied systematically. We performed a serial analysis of gene expression in both human and murine MLL-ELL or MLL-ENL leukemia cells and identified 88 genes that seemed to be significantly deregulated in both types of leukemia cells, including 57 genes not reported previously as being deregulated in MLL-associated leukemias. These changes were validated by quantitative PCR. The most up-regulated genes include several HOX genes (e.g., HOX A5, HOXA9, and HOXA10) and MEIS1, which are the typical hallmark of MLL rearrangement leukemia. The most down-regulated genes include LTF, LCN2, MMP9, S100A8, S100A9, PADI4, TGFBI, and CYBB. Notably, the up-regulated genes are enriched in gene ontology terms, such as gene expression and transcription, whereas the down-regulated genes are enriched in signal transduction and apoptosis. We showed that the CpG islands of the down-regulated genes are hypermethylated. We also showed that seven individual microRNAs (miRNA) from the mir-17-92 cluster, which are overexpressed in human MLL rearrangement leukemias, are also consistently overexpressed in mouse MLL rearrangement leukemia cells. Nineteen possible targets of these miRNAs were identified, and two of them (i.e., APP and RASSF2) were confirmed further by luciferase reporter and mutagenesis assays. The identification and validation of consistent changes of gene expression in human and murine MLL rearrangement leukemias provide important insights into the genetic base for MLL-associated leukemogenesis.