Andrew L. Weinstein

Hydrogen Sulfide Protects Against Ischemia-Reperfusion Injury in an In Vitro Model of Cutaneous Tissue Transplantation

BACKGROUND Ischemia-reperfusion injury (IRI) is a source of morbidity and mortality in many clinical scenarios, and has as one of its many consequences the induction of cellular apoptosis. Hydrogen sulfide (H2S) may decrease cellular metabolism in a reversible, nontoxic manner. An in vitro model of cutaneous tissue transplantation was developed to assess whether H2S could ameliorate cellular injury caused by IRI. METHODS Human umbilical vein endothelial cells (HUVECs) were treated with media containing NaHS (0, 10 microM, 100 microM, or 1 mM) and exposed to normoxia (21% oxygen), hypoxia (1%), or anoxia (0%). Cells were then returned to normoxia, and apoptosis was quantified using a terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay. Fibroblasts (3T3s) were treated with H2S and exposed to anoxia in a similar fashion. RESULTS Treatment with H2S resulted in a significant decrease in apoptosis in HUVECs and 3T3s subjected to IRI. Toxicity of H2S was not observed, although the protective effect was less evident at higher doses. CONCLUSION This is the first study to examine H2S and the cellular components of cutaneous flaps in the setting of IRI. Our results demonstrate that H2S significantly decreases apoptosis in vitro in the setting of IRI. These data suggest H2S may mitigate IRI in vivo, and, therefore, has potential as a therapy for improving tissue survivability in clinical scenarios.

Therapeutic Metabolic Inhibition: Hydrogen Sulfide Significantly Mitigates Skeletal Muscle Ischemia Reperfusion Injury In Vitro and In Vivo

Background: Recent evidence suggests that hydrogen sulfide is capable of mitigating the degree of cellular damage associated with ischemia-reperfusion injury. The purpose of this study was to determine whether it is protective in skeletal muscle. Methods: This study used both in vitro (cultured myotubes subjected to sequential anoxia and normoxia) and in vivo (mouse hind-limb ischemia followed by reperfusion) models in which hydrogen sulfide (0 to 1000 &mgr;M) was delivered before the onset of oxygen deficiency. Injury score and apoptotic index were determined by analysis of specimens stained with hematoxylin and eosin and terminal deoxynucleotidyl transferase–mediated dUTP nick end labeling, respectively. Results: In vitro, hydrogen sulfide reduced the apoptotic index by as much as 99 percent (p = 0.001), with optimal protection conferred by raising intravascular hydrogen sulfide to 10 &mgr;M. In vivo, 10 &mgr;M hydrogen sulfide delivered before 3 hours of hind-limb ischemia followed by 3 hours of reperfusion resulted in protection against ischemia-reperfusion injury–induced cellular changes, as evidenced by significant decreases in injury score and apoptotic index (by as much as 91 percent; p = 0.001). These findings were consistent at 4 weeks after injury and reperfusion. Conclusion: These findings confirm that the preischemic delivery of hydrogen sulfide limits ischemia-reperfusion injury–induced cellular damage in myotubes and skeletal muscle and suggests that, when given in the appropriate dose, this molecule may have significant therapeutic applications in multiple clinical scenarios.

Therapeutic delivery of hydrogen sulfide for salvage of ischemic skeletal muscle after the onset of critical ischemia

BACKGROUND Recent evidence suggests that hydrogen sulfide is capable of mitigating the degree of cellular damage associated with ischemia-reperfusion injury (IRI). METHODS This study evaluated the potential utility of hydrogen sulfide in preventing IRI in skeletal muscle by using in vitro (cultured myotubes subjected to sequential hypoxia and normoxia) and in vivo (mouse hind limb ischemia, followed by reperfusion) models to determine whether intravenous hydrogen sulfide delivered after the ischemic event had occurred (pharmacologic postconditioning) conferred protection against IRI. Injury score and apoptotic index were determined by analysis of specimens stained with hematoxylin and eosin and terminal deoxynucleotide transferase-mediated deoxy-uridine triphosphate nick-end labeling, respectively. RESULTS In vitro, hydrogen sulfide reduced the apoptotic index after 1, 3, or 5 hours of hypoxia by as much as 75% (P = .002), 80% (P = .006), and 83% (P < .001), respectively. In vivo, hydrogen sulfide delivered after the onset of hind limb ischemia and before reperfusion resulted in protection against IRI-induced cellular changes, which was validated by significant decreases in the injury score and apoptotic index. The timing of hydrogen sulfide delivery was crucial: when delivered 20 minutes before reperfusion, hydrogen sulfide conferred significant cytoprotection (P < .001), but treatment 1 minute before reperfusion did not provide protection (P = NS). CONCLUSIONS These findings confirm that hydrogen sulfide limits IRI-induced cellular damage in myotubes and skeletal muscle, even when delivered after the onset of ischemia in this murine model. These data suggest that when given in the appropriate dose and within the proper time frame, hydrogen sulfide may have significant therapeutic applications in multiple clinical scenarios.

A portable high-intensity focused ultrasound device for noninvasive venous ablation

BACKGROUND Varicose veins and other vascular abnormalities are common clinical entities. Treatment options include vein stripping, sclerotherapy, and endovenous laser treatment, but all involve some degree of invasive intervention. The purpose of this study was to determine ex vivo the effectiveness of a novel hand-held, battery-operated, high-intensity focused ultrasound (HIFU) device for transcutaneous venous ablation. METHODS The ultrasound device is 14 x 9 x 4 cm, weighs 650 g, and is powered by 4 lithium ion battery packs. An ex vivo testing platform consisting of two different models comprised of sequentially layered skin-muscle-vein or skin-fat-vein was developed, and specimens were treated with HIFU. The tissues were then disassembled, imaged, and processed for histology. The luminal cross-sectional area of vein that had been treated with HIFU and nontreated controls were measured, and the values presented as median and interquartile range (IQR). The values were compared using a Wilcoxon rank-sum test, and statistical significance was set at P < .05. RESULTS On gross and histologic examination, veins that had been treated with HIFU showed evidence of coagulation necrosis. The surface of the muscle in direct contact with the vein had a pinpoint area of coagulation, whereas the adjacent fat appeared undisturbed; the skin, fat, and the surface of the muscle in contact with the transducer remained completely unaffected. The cross-sectional area was 3.79 mm(2) (IQR, 3.38-4.22) of the control vein lumen and 0.16 mm(2) (IQR, 0.04-0.39) in those that had been treated with HIFU (P = .0304). CONCLUSION This inexpensive, portable HIFU device has the potential to allow clinicians to easily perform venous ablation in a manner that is entirely noninvasive and without the expense or inconvenience of large, complicated devices. This device represents a significant step forward in the development of new applications for HIFU technology.

A rapidly resorbable hemostatic biomaterial based on dihydroxyacetone.

We have developed a rapid acting, rapidly resorbable, non-toxic, topical hemostatic agent comprised of a PEGylated, polymerized sequence of dihydroxyacetone (MPEG-pDHA) that is highly effective in vivo. Twenty-eight Sprague-Dawley rats underwent left lateral hepatectomy. To the cut edge of the liver, rats received MPEG-pDHA (50 mg), normal saline (0.5 mL), or Instat (50 mg), a commercially available hemostatic compound. Bleeding time and total blood loss were quantified. Coagulation studies and scanning electron microscopy were performed on phlebotomized blood combined with MPEG-pDHA. Rats treated with MPEG-pDHA had significantly decreased bleeding time (97 s) and total blood loss (1.35 g) compared to normal saline (464 s and 3.83 g, p < 0.05 for each), and a significantly shorter bleeding time compared to Instat (165 s, p < 0.05). Histology confirmed that all MPEG-pDHA was metabolized within 3 weeks. The addition of MPEG-pDHA to whole blood did not significantly affect prothrombin time (12.0 s vs. 13.2 s, p = 0.130), partial thromboplastin time (27.0 s vs. 21.8 s, p = 0.118), or thrombin clotting time. MPEG-pDHA is an effective and rapidly resorbable hemostatic agent that may find broad hemostatic application in a wide range of surgical procedures.

Intraoperative Comparison of Anatomical versus Round Implants in Breast Augmentation: A Randomized Controlled Trial

Background: The purpose of this randomized controlled trial was to determine whether anatomical implants are aesthetically superior to round implants in breast augmentation. Methods: Seventy-five patients undergoing primary breast augmentation had a round silicone implant of optimal volume, projection, and diameter placed in one breast and an anatomical silicone device of similar volume and optimal shape placed in the other. After intraoperative photographs were taken, the anatomical device was replaced by a round implant to complete the procedure. A survey designed to measure breast aesthetics was administered to 10 plastic surgeon and 10 lay reviewers for blind evaluation of the 75 cases. Results: No observable difference in breast aesthetics between anatomical and round implants was reported by plastic surgeons in 43.6 percent or by lay individuals in 29.2 percent of cases. When a difference was perceived, neither plastic surgeons nor lay individuals preferred the anatomical side more often than the round side. Plastic surgeons judged the anatomical side superior in 51.1 percent of cases and the round side superior in 48.9 percent of cases (p = 0.496). Lay individuals judged the anatomical side superior in 46.7 percent of cases and the round side superior in 53.3 percent (p = 0.140). Plastic surgeons identified implant shape correctly in only 26.5 percent of cases. Conclusions: This study provides high-level evidence supporting no aesthetic superiority of anatomical over round implants. Given that anatomical implants have important and unique disadvantages, a lack of proven aesthetic superiority argues against their continued use in breast augmentation. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, I.

Social networking services: implications for the next generation of physicians.

In 2010, the social networking service (SNS) Facebook surpassed Google as the most-visited site in the United States, according to the Internet analytics firm Experian Hitwise. The far-reaching success of SNSs is based on their ability to keep friends and family connected as well as to promote new connections between strangers with similar interests. Recently, however, it has become apparent that the modes through which SNSs accomplish these goals expose users to a plethora of privacy risks. For members of the medical community in particular, for whom the perception of professionalism is crucial to maintaining public trust, posting unprofessional material on SNSs compromises the boundaries that protect the physician–patient relationship and challenges the reputation of the medical profession. Current research indicates that medical professionals and preprofessionals commonly belong to SNSs with the highest rate of use among the youngest individuals. Mostaghimi et al characterized websites of 250 Massachusetts physicians with a median of 18 years since medical school graduation and determined that 10.8% had SNS profiles. The authors used Google to collect their data set, thus indicating that it is possible for anyone with an Internet connection to identify physicians on SNSs. Considering a younger population, Thompson et al showed that 13% of residents and 64% of medical students at the University of Florida, Gainesville had Facebook profiles. Taken together, these studies suggest that there might be a 6-fold

Hydrogen sulfide attenuates ischemia-reperfusion injury in in vitro and in vivo models of intestine free tissue transfer.

Background: Ischemia-reperfusion injury is the propagation of injury following reintroduction of oxygen to previously ischemic tissue. The purpose of this study was to evaluate whether hydrogen sulfide provides protection against ischemia-reperfusion injury in enteric tissue. Methods: In vitro (enterocyte anoxia-normoxia) and in vivo (rat intestinal ischemia-reperfusion) models of ischemia-reperfusion injury were tested with or without the addition of hydrogen sulfide. Apoptotic index was determined in vitro, and gross appearance, histology, and villus height (a measure of mucosal integrity) were assessed in vivo. Statistical analysis was performed, and significance was defined as p < 0.05. Results: In vitro, cells treated with 10 &mgr;M hydrogen sulfide after 1-hour anoxia experienced a significant decrease in apoptotic index compared with untreated control (0.5 ± 0.3 percent versus 2.8 ± 0.7 percent); after 3 hours of anoxia, cells treated with 1 &mgr;M, 10 &mgr;M, and 100 &mgr;M hydrogen sulfide experienced significant decreases in apoptotic index versus untreated control (1.6 ± 0.8 percent, 1.8 ± 0.9 percent, and 2.8 ± 0.7 percent versus 8.6 ± 1.7 percent). In vivo, intestine treated with [10 &mgr;M] or [100 &mgr;M] hydrogen sulfide retained normal coloration and villus architecture after 1-hour ischemia; after 2 hours of ischemia, only intestine treated with [10 &mgr;M] hydrogen sulfide appeared uninjured. After 1, 2, or 3 hours of ischemia, villus heights of intestine treated with [10 &mgr;M] or [100 &mgr;M] hydrogen sulfide were significantly higher than heights of non–hydrogen sulfide-treated villi. Conclusions: Hydrogen sulfide significantly attenuates ischemia-reperfusion injury in intestinal tissue in vitro and in vivo. These results have significant implications for enteric free tissue transfers and other gastrointestinal procedures in which ischemic intervals may be anticipated.

Hydrogen sulfide attenuates intestinal ischemia-reperfusion injury when delivered in the post-ischemic period

Background and Aim:  To investigate whether pharmacologic post‐conditioning of intestinal tissue with hydrogen sulfide (HS) protects against ischemia reperfusion injury (IRI).

A Prospective Analysis of the Association Between Indwelling Surgical Drains and Surgical Site Infection in Plastic Surgery

IntroductionMany surgeons fear that closed-suction drains serve as a portal for bacterial entry into surgical spaces. Despite a lack of supporting evidence, postoperative antibiotics are often prolonged while drains remain in place. MethodsMedical records of all patients who underwent intraoperative Jackson-Pratt drain placement and sterile removal over a 12-month period were prospectively analyzed. ResultsFifty-four patients with 101 drains were included. Drains were in place for 5 to 43 days [mean (SD), 13.5 (6.3) days]. Sixty-three percent of drains had positive cultures. All patients received perioperative antibiotics. Thirty-nine patients received postoperative antibiotics [mean (SD), 13.8 (13.8) days]. There were 2 cases of cellulitis. One patient required reoperation. ConclusionsSixty-six drains (65.3%) were placed in the presence of prosthetic material. Although nearly two thirds of drains were colonized with bacteria, our wound infection rate was extremely low (5.6%). Thus, closed-suction drains may be left in place for an extended period without increasing the risk of infection, even in the presence of prosthetic material.