Steven M. Levine

Polymorphisms of Helicobacter pylori HP0638 Reflect Geographic Origin and Correlate with cagA Status

ABSTRACT Since the associations between Helicobacter pylori genotype and disease differ in Asia and the West, we investigated the correlation between HP0638, encoding an outer membrane protein, and potential markers of virulence (cagA, vacA, and iceA). For 109 strains from nine countries, the status of cagA, vacA, and iceA was determined by PCR and/or a line probe assay. We also studied 18 strains from 8 patients (parents and 6 daughters) from a Dutch family and paired strains collected on average 8 years apart from 11 patients. When the HP0638 signal sequences were amplified by PCR and DNA sequence determinations were performed, 89 (96%) of 93 cagA-positive strains had HP0638 in frame, versus none (0%) of 16 cagA-negative strains (P < 0.001). Among strains in which HP0638 was in frame, a six-CT dinucleotide repeat pattern was dominant in Western countries (23 of 33 strains [70%]), while a pattern of three CT repeats with another CT after four T’s (3 + 1-CT-repeat pattern) was dominant in East Asia (31 of 46 strains [67%]); however, specific CT repeat patterns did not correlate with clinical outcome. HP0638 phylogenetic trees also showed geographic characters. The HP0638 frame status and CT dinucleotide repeat patterns were identical for 9 of 11 pairs of strains obtained on average 8 years apart from individuals and the 15 strains obtained from the mother and all six daughters. Thus, HP0638 frame status and cagA status are strongly correlated. The CT dinucleotide repeat pattern in the putative HP0638 signal sequence has geographic characters and appears stable in particular patients and families over a period of years. Analysis of HP0638 CT polymorphisms may serve as a new typing system to discriminate H. pylori isolates for epidemiological purposes.

Natural Transformation of Helicobacter pylori Involves the Integration of Short DNA Fragments Interrupted by Gaps of Variable Size

Helicobacter pylori are gram-negative bacteria notable for their high level of genetic diversity and plasticity, features that may play a key role in the organisms ability to colonize the human stomach. Homeologous natural transformation, a key contributor to genomic diversification, has been well-described for H. pylori. To examine the mechanisms involved, we performed restriction analysis and sequencing of recombination products to characterize the length, fragmentation, and position of DNA imported via natural transformation. Our analysis revealed DNA imports of small size (1,300 bp, 95% confidence limits 950–1850 bp) with instances of substantial asymmetry in relation to selectable antibiotic-resistance markers. We also observed clustering of imported DNA endpoints, suggesting a possible role for restriction endonucleases in limiting recombination length. Additionally, we observed gaps in integrated DNA and found evidence suggesting that these gaps are the result of two or more separate strand invasions. Taken together, these observations support a system of highly efficient short-fragment recombination involving multiple recombination events within a single locus.

PCR-Based Detection of Bacillus anthracis in Formalin-Fixed Tissue from a Patient Receiving Ciprofloxacin

ABSTRACT We demonstrate that Bacillus anthracis may be detected from a formalin-fixed, paraffin-embedded biopsy specimen, even after the patient has received antibiotic treatment. Although traditional PCR methods may not be sufficiently sensitive for anthrax detection in such patients, cycle numbers can be increased or PCR can be repeated by using an aliquot from a previous PCR as the template.

Plastic cells and populations: DNA substrate characteristics in Helicobacter pylori transformation define a flexible but conservative system for genomic variation

Helicobacter pylori, bacteria that colonize the human gastric mucosa, are naturally competent for transformation by exogenous DNA, and show a panmic‐tic population structure. To understand the mechanisms involved in its horizontal gene transfer, we sought to define the interval required from exposure to substrate DNA until DNA uptake and expression of a selectable phenotype, as well as the relationship of transforming fragment length, concentration, homol‐ogy, symmetry, and strandedness, to the transformation frequency. We provide evidence that natural transformation in H. pylori differs in efficiency among wild‐type strains but is saturable and varies with substrate DNA length, symmetry, strandedness, and species origin. We show that H. pylori cells can be transformed within one minute of contact with DNA, by DNA fragments as small as 50 bp, and as few as 5 bp on one flank of a selectable single nucleotide mutation is sufficient substrate for recombination of a transforming fragment, and that double‐stranded DNA is the preferred (1000‐fold > single‐stranded) substrate. The high efficiency of double‐stranded DNA as transformation substrate, in conjunction with strain‐specific restriction endonucle‐ases suggests a model of short‐fragment recombination favoring closest relatives, consistent with the observed H. pylori population biology.—Levine S. M., Lin, E. A., Emara, W., Kang, J., DiBenedetto, M., Ando, T., Falush, D., Blaser M. J. Plastic cells and populations: DNA substrate characteristics in Helicobacter pylori transformation define a flexible but conservative system for genomic variation. FASEB J. 21, 3458–3467 (2007)

Free tissue transfer to the lower extremity distal to the zone of injury: indications and outcomes over a 25-year experience.

Background: Microvascular free flap anastomoses performed for lower extremity reconstruction are traditionally proximal to the zone of injury. The authors assessed the feasibility and outcomes of microvascular free flaps with anastomoses performed distal to the zone of injury. Methods: The authors retrospectively reviewed all microvascular free flaps performed at their institution over the past 10 years for lower extremity reconstruction and compared this group with their previously published experience (January of 1979 through August of 1995). Between September of 1995 and May of 2005, 119 flap procedures were performed for lower extremity reconstruction. Twenty-eight flaps (24 percent) were anastomosed distal to the zone of injury and 87 (76 percent) were anastomosed proximally. There were insufficient data on the location of the anastomosis for four free flaps (all successful). Results: Twenty-seven of 28 distal microvascular free flaps were successful (96 percent); two (7 percent) required emergent postoperative reexploration of the anastomosis. Of the 87 proximal flaps, 79 (91 percent) were successful and eight (9 percent) failed. There was no statistically significant difference in the success rate of microvascular free flaps between the proximal and distal anastomosis groups (p = 0.30, Fisher’s exact test). Combined with the data from the authors’ previous series (January of 1979 to August of 1995), there were 63 free flaps with anastomosis performed distal to the zone of injury; 61 (97 percent) were successful. Conclusion: The authors’ extensive 25-year experience with lower extremity reconstruction demonstrates that in appropriately selected patients, free tissue transfer to recipient vessels distal to the zone of injury is reliable and in certain cases preferable.

Outcomes of delayed abdominal-based autologous reconstruction versus latissimus dorsi flap plus implant reconstruction in previously irradiated patients.

BackgroundLocal recurrence after breast conservation therapy is usually managed with salvage mastectomy. Multiple methods of reconstruction are possible, although delayed autologous reconstruction provides the most reliable results. MethodsWe compared complications in delayed abdominal-based [transverse rectus abdominis muscle (TRAM)/deep inferior epigastric perforator (DIEP)] reconstruction with delayed latissimus dorsi plus implant-based reconstruction in previously irradiated breasts. The authors reviewed 133 consecutive cases of delayed breast reconstructions performed in patients who had postmastectomy radiation therapy and reconstruction with abdominal-based methods (single-pedicle TRAM, supercharged pedicle TRAM, muscle-sparing TRAM free flap, DIEP flap, and superficial inferior epigastric artery flap) or a pedicled latissimus dorsi flap plus implant. Complications for donor and recipient sites were recorded including infection, seroma, hematoma, and partial flap loss. ResultsSeventy-five patients were reconstructed with abdominal-based flaps (37 muscle-sparing TRAMs, 19 pedicled TRAMs, 12 DIEPs, 6 supercharged pedicled TRAMs, and 1 superficial inferior epigastric artery). Their median age was 50 years and mean follow-up was 22.7 months. Three (4.0%) patients required reoperation during the same hospital visit for vascular compromise that resulted in 2 (2.7%) flap failures. Three (4.0%) patients had partial flap loss that ultimately required debridement and primary closure. Seventeen (22.7%) patients had minor complications including seroma, small hematoma, cellulitis, and abdominal bulge. Fifty-six patients were reconstructed with latissimus dorsi flaps plus implants. Their median age was 47 years and mean follow-up was 32 months. Three (5.4%) patients developed infections resulting in implant loss. Four (7.1%) patients had partial flap loss that required debridement and primary closure. Thirteen (23.2%) patients had minor complications including seroma (12 patients) and hematoma (1 patient) that required drainage. Fisher exact test was used to determine statistical significance of complication and failure rates between the 2 types of reconstruction. In patients who had postmastectomy radiation therapy, those with abdominal-based reconstructions had fewer complications compared with latissimus dorsi flap plus implant reconstructions (28.0% vs 30.4%, P = 0.846). Also, fewer reconstructions failed in patients with abdominal-based reconstruction (2.7% vs 5.4%, P = 0.650). ConclusionsAbdominal-based autologous reconstruction had fewer complications and fewer reconstruction failures than latissimus dorsi flap plus implant reconstructions in patients with postmastectomy radiation therapy in our series; however, these rates were not statistically significant.

Evidence-based medicine: liposuction.

Learning Objectives: After reading this article, the participant should be able to: 1. Perform preoperative assessment and patient selection for liposuction surgeries. 2. Explain the differences among the various types of anesthesia and wetting solutions used in liposuction. 3. Identify the available literature about skin-tightening procedures. 4. Convey to patients the complication profile for various modalities of liposuction. 5. Recall important ASPS consensus guidelines when discussing liposuction. Summary: The article was prepared to feature recent evidence-based publications pertaining to liposuction. The authors placed special emphasis on the most clinically relevant data. In addition, they highlighted current data regarding liposuction-related fields, including autologous fat transfer and minimally invasive skin tightening.

Surgical Treatment of Malignant Melanoma Practical Guidelines

Melanoma is currently the fifth and sixth most common solid malignancy diagnosed in men and women, respectively. Although accounting for only 4% of cases of all cutaneous malignancies, melanoma accounts for more than 75% of all deaths from skin cancer. This article discusses epidemiology and risk factors, proper biopsy technique, advanced histologic evaluation of biopsy material, assessment of tumor thickness and staging, preoperative metastatic evaluation, excision margin, treatment of regional lymph nodes, treatment of recurrence, and some special clinical situations.

An evidence-based approach to the surgical management of pressure ulcers.

ObjectiveThis study aims to use the evidenced-based approach to better understand the surgical management and treatment of pressure ulcers. Summary of Background DataPressure sores are a cause of significant morbidity in the medical community. Although there are a multitude of preventative and treatment options, there remains some degree of uncertainty in the literature in defining the best way to treat and manage pressure sores. MethodsAn exhaustive literature search was performed using several electronic databases. The search revealed several identified modalities for treatment of pressure ulcers. We then assessed each modality individually for the level of evidence that exists in the most current literature, with preference given to more recent studies (2005-present). ResultsHere, we reviewed the most relevant, high-level evidence that exists for the following modalities for managing pressure ulcers from a surgical perspective: wound cleansers, repositioning, negative pressure therapy, enteral and parenteral feeding, vitamin and mineral supplementation, specialized mattresses, ultrasound therapy, honey, cellular therapy, debridement, ostectomy, and musculocutaneous and fasciocutaneous flap closure. ConclusionsAlthough many of the previously mentioned modalities are used, we encourage clinicians and health care providers to consider the evidence-based data when deciding how to most appropriately manage their patient’s pressure sores.

Perforator Flap Breast Reconstruction After Unsatisfactory Implant Reconstruction

In 2009, 86,424 breast reconstructions were performed in the United States, with 76% being implant-based procedures. Capsular contracture and infection are the 2 most cited indications for implant explantation, resulting in a reconstruction failure. However, several patients are dissatisfied with implant reconstruction even without the aforementioned complications. We hypothesize that microvascular autologous tissue transfer with perforator free-flap breast reconstruction provides an excellent salvage modality in the face of an unsatisfactory implant reconstruction, resulting in an improved cosmetic and functional outcome, with low risk of complications. We retrospectively reviewed the charts of patients in the senior authors practice who underwent perforator flap breast reconstruction between the years 1998 through 2008, and identified all patients who had prior implant reconstruction. Indications for implant explantation, medical history, operative procedure, and postoperative complications were reviewed. During the study period, 1846 perforator flaps were performed. We found 191 patients who underwent autologous breast reconstruction after implant reconstruction with a total of 284 flaps (15.4%). The most frequent patient complaint was unnatural appearance and feel of the implants (Baker I or Baker II), and the majority of patients had not undergone radiation. Most patients were reconstructed using abdominal flaps with 164 deep inferior epigastric perforators, 50 superior gluteal artery perforators, 30 superficial inferior epigastric arteries, 35 inferior gluteal artery perforators, and 5 transverse upper gracilis. The total complication rate was 7.4%, with most complications related to wound healing at the donor site. There were 3 flap losses (1%), all of which were later successfully reconstructed with another perforator flap. Implant failures are traditionally thought to be in patients with Baker grade III/IV capsular contractures and in patients status post radiation therapy. However, in our study, the majority of patients seeking perforator flap reconstruction after implant reconstruction complained of an unnatural feel and appearance of their breasts, and did not have a severe capsular contracture deformity (Baker III/IV), nor had they undergone radiation. This suggests that implant reconstruction can lead to patient dissatisfaction severe enough to warrant removal even with Baker I/II results, and not in the setting of postradiation changes.