Kayvan T. Khiabani

Levels of Evidence in Research Published in The Journal of Bone and Joint Surgery (American Volume) Over the Last Thirty Years

BACKGROUND The recent emphasis on evidence-based medicine has led to increasing levels of evidence being published in surgical journals. The purpose of the present study was to review the levels of evidence in reports published in The Journal of Bone and Joint Surgery (American Volume) over the last thirty years. METHODS We reviewed all of the articles published in The Journal in the years 1975, 1985, 1995, and 2005. Cadaver studies, animal studies, basic-science studies, review articles, Instructional Course Lectures, and correspondence were excluded. Articles were scored according to The Journals levels of evidence for a primary research question. RESULTS A total of 1058 articles were reviewed. Of these, 134, 123, 120, and 174 articles met the inclusion criteria for the years 1975, 1985, 1995, and 2005, respectively, and were ranked according to level of evidence. The number of articles for each level of evidence rating was then expressed as a percentage of the total number of articles meeting the inclusion criteria for that year. There was a significant trend toward higher levels of evidence, with the combined percentage of Level-I, II, and III studies increasing from 17% to 52% (p < 0.01). The percentage of Level-I studies increased from 4% in 1975 to 21% in 2005. The average level of evidence rating improved from 3.72 to 2.90 during the study period. CONCLUSIONS The level of evidence in The Journal has improved significantly over the last thirty years.

Melatonin reduces ischemia/reperfusion-induced superoxide generation in arterial wall and cell death in skeletal muscle

Abstract:  The purpose of this study was to determine the effect of melatonin on superoxide generation in arterial wall at an early phase of reperfusion and on endothelial dysfunction of microvasculature and cell viability of cremaster muscle at late phase of reperfusion (24 hr) after prolonged ischemia. Bilateral vascular pedicles which supply blood flow to the cremaster muscle were exposed. After surgical preparation, microvascular clamps were applied on the right iliac, femoral and spermatic arteries to create 4 hr of ischemia in both feeding vessels and the unexposed cremaster muscle. The vascular clamping was omitted on the left iliac, femoral and spermatic arteries and served as an internal control. Melatonin or Vehicle was via by intravenous injection at 10 min prior to reperfusion and 10 min after reperfusion. In the first experiment, the vascular pedicle was harvested after reperfusion to measure superoxide generation in real time by lucigenin‐derived chemiluminescence. In the second experiment, endothelial‐dependent and ‐independent vasodilatation was examined in the terminal arteriole of cremaster muscle which was then harvested to examine cell viability by WST‐1 assay on day 2. Superoxide generation in arterial wall peaked at first 5‐min of reperfusion and declined to near baseline after 60 min of reperfusion. Melatonin treatment significantly reduced superoxide generation in arterial walls and improved cell viability in cremaster muscles. Melatonin treatment also significantly reduced microvascular endothelial dysfunction which was still observable in the microcirculation of cremaster muscle after 24 hr of reperfusion. Melatonin reduces superoxide generation in the early phase of reperfusion resulting in attenuating endothelial dysfunction and muscle cell death in the late phase of reperfusion.

Melatonin attenuates I/R-induced mitochondrial dysfunction in skeletal muscle.

BACKGROUND Our recent studies have shown that ischemia/reperfusion (I/R) produces significant necrosis and apoptosis in the cells of skeletal muscle. Our previous studies also demonstrated that melatonin provides significant protection against superoxide generation, endothelial dysfunction, and cell death in the skeletal muscle after I/R. Mitochondria are essential for cell survival, because of their roles as ATP producers as well as regulators of cell death. However, the efficacy of melatonin on I/R-induced mitochondrial dysfunction in the skeletal muscle in vivo has not been demonstrated in the literature. MATERIALS AND METHODS Vascular pedicle isolated rat gracilis muscle model was used. After 4 h of ischemia followed by 24 h of reperfusion, gracilis muscle was harvested, and mitochondrial as well as cytosolic fractions were isolated. Mitochondrial dysfunction was determined by the alteration of mitochondrial membrane potential and the release of the proapoptotic protein, cytochrome c. Three groups were designed; sham I/R, I/R-V (I/R with vehicle), and I/R-Mel (I/R with melatonin). Melatonin or vehicle was given intravenously 10 min prior to reperfusion and 10 min after reperfusion. RESULTS We found that the capability of uptake of fluorescent JC-1 dye in skeletal muscle cells was substantially improved in I/R-Mel group compared with I/R-V group. Melatonin significantly inhibited the outflow of cytochrome c from mitochondria to cytoplasm, which was demonstrated in the I/R-V group. CONCLUSIONS Melatonin significantly attenuates I/R-induced mitochondrial dysfunction, such as the depolarization of mitochondrial membrane potential and the release of the proapoptotic protein, cytochrome c, from the mitochondria.

Contributing Variables to Post Mastectomy Tissue Expander Infection

Abstract:  Tissue expander breast reconstruction is a common post mastectomy breast procedure performed by plastic surgeons. The purpose of this study was to define the incidence of breast reconstruction prosthetic infection, relate patient characteristics with increased rate of infection, and analyze the influence of postoperative complications to expander/implant infection. A retrospective, single‐institution chart review of 195 women with post mastectomy tissue expander/implant reconstructions performed from 2006 through 2008 was conducted. Total periprosthetic infection rate was calculated. Patient factors, operative technique, and noninfectious complications were analyzed and related to increased periprosthetic infection rate. A binary logistic regression model was fitted using periprosthetic infection as the dependent variable and 12 patient characteristics as independent variables, followed by a step‐wise model for best fit with a limited number of independent variables. The overall periprosthetic infection rate per patient over the 2 year period was 5.1%. The incidence of periprosthetic infection per reconstructed breast was 3.2%. Odds ratio estimates indicated that the presence of cellulitis increased the odds of periprosthetic infection more than 200 times (p = <0.0001), and inpatient procedures increased the odds 16 times (p = 0.02). Other variables (i.e., age > 65, DM, flap necrosis, smoking, dehiscence, AlloDerm, etc) failed to reach statistical significance (p > 0.05). Postoperative breast cellulitis and inpatient status appear to be significant risk factors for increased periprosthetic infection. No significant increase in periprosthetic infection rate was noted with other variables in this model.

Microcirculatory effects of melatonin in rat skeletal muscle after prolonged ischemia.

Abstract:  The purpose of this study was to determine microcirculatory effects and response of nitric oxide synthase (NOS) to melatonin in skeletal muscle after prolonged ischemia. A vascular pedicle isolated rat cremaster muscle model was used. Each muscle underwent 4 hr of zero‐flow warm ischemia followed by 2 hr of reperfusion. Melatonin (10 mg/kg) or saline as a vehicle was given by intraperitoneal injection at 30 min prior to reperfusion and the same dose was given immediately after reperfusion. After reperfusion, microcirculation measurements including arteriole diameter, capillary perfusion and endothelial‐dependent and ‐independent vasodilatation were performed. The cremaster muscle was then harvested to measure endothelial NOS (eNOS) and inducible NOS (iNOS) gene expression and enzyme activity. Three groups of rats were used: sham‐ischemia/reperfusion (I/R), vehicle + I/R and melatonin + I/R. As compared with vehicle + I/R group, administration of melatonin significantly enhanced arteriole diameter, improved capillary perfusion, and attenuated endothelial dysfunction in the microcirculation of skeletal muscle after 4 hr warm ischemia. Prolonged warm ischemia followed by reperfusion significantly depressed eNOS gene expression and constitutive NOS activity and enhanced iNOS gene expression. Administration of melatonin did not significantly alter NOS gene expression or activity in skeletal muscle after prolonged ischemia and reperfusion. Melatonin provided a significant microvascular protection from reperfusion injury in skeletal muscle. This protection is probably attributable to the free radical scavenging effect of melatonin, but not to its anti‐inflammatory effect.

Hyperbaric Oxygen Inhibits Ischemia-reperfusion–induced Neutrophil Cd18 Polarization by a Nitric Oxide Mechanism

Background: Hyperbaric oxygen decreases ischemia-reperfusion–induced neutrophil/intercellular adhesion molecule-1 adhesion by blocking CD18 polarization. The purpose of this study was to evaluate whether this hyperbaric oxygen effect is nitric oxide dependent and to determine whether nitric oxide synthase is required. Methods: A gracilis muscle flap was raised in nine groups of male Wistar rats. Global ischemic injury was induced by clamping the gracilis muscle pedicle artery and vein for 4 hours. The hyperbaric oxygen treatment consisted of 100% oxygen at 2.5 atm absolute during the last 90 minutes of ischemia. Groups were repeated with and without various nitric oxide synthase inhibitors and carboxy-2-phenyl-4,4,5,5,-tetramethylimidazoline-1-oxyl-3-oxide (C-PTIO), a nitric oxide scavenger. Normal neutrophils were exposed to activated plasma on intercellular adhesion molecule-1–coated coverslips (percentage adherent) and labeled with fluorescein isothiocyanate/antirat-CD11b for confocal microscopy (percentage polarized). The percentage of adherent and polarized cells was reported as mean ± SEM. Statistical analysis was by analysis of variance. A value of p ≤ 0.05 was considered significant. Results: C-PTIO–treated ischemia-reperfusion/hyperbaric oxygen plasma showed a significant increase in the percentage polarization of CD18 compared with ischemia-reperfusion/hyperbaric oxygen–untreated plasma from 4.1 ± 2.5 percent to 33.7 ± 7.7 percent (p ≤ 0.05). The nitric oxide scavenger C-PTIO also increased the percentage of adherent cells from 1.6 ± 0.4 percent to 20.3 ± 5.9 percent (p ≤ 0.05). Administration of NG-nitro-L-arginine methyl ester and other nitric oxide synthase inhibitors before hyperbaric oxygen treatment restored neutrophil adhesion and CD18 polarization to ischemia-reperfusion control values, significantly greater than ischemia-reperfusion/hyperbaric oxygen alone. Conclusion: These results suggest that the hyperbaric oxygen reduction of ischemia-reperfusion–induced neutrophil polarization of CD18 and adherence to intercellular adhesion molecule-1 is mediated through a nitric oxide mechanism that requires nitric oxide synthase.

The effects of the nitric oxide donor SIN-1 on ischemia-reperfused cutaneous and myocutaneous flaps.

Ischemia-reperfusion injury causes tissue damage that leads to a decrease in bioavailability of nitric oxide. The authors hypothesized that an exogenous supply of nitric oxide will have beneficial effects on survival of skin and skeletal muscle subjected to ischemia-reperfusion injury. By using the nitric oxide donor SIN-1 (3-morpholino-sydnonimine) the effects of direct intraarterial infusion of an exogenous source of nitric oxide in reperfused flaps was studied. Bilateral island buttock skin flaps and latissimus dorsi myocutaneous flaps were elevated in eight pigs, for a total of 32 flaps. Flaps were subjected to 6 hours of ischemia followed by 18 hours of reperfusion. Flaps on one side of each animal were randomized to be treated with the nitric oxide donor (treatment group). The contralateral side was treated with an equivalent volume of saline vehicle (infusion control) SIN-1, or saline was administered as a continuous direct intraarterial infusion at the onset of reperfusion and continued during the observation period. Outcomes measured were tissue neutrophil accumulation by using myeloperoxidase assay and tissue survival (intravenous fluorescein and nitroblue tetrazolium for skin and muscle, respectively). In both skin and myocutaneous flaps, SIN-1 treatment caused a significant improvement in survival and a decrease in neutrophil accumulation. Nitric oxide may play an important role in the pathophysiologic process of ischemia-induced reperfusion injury in skin and skeletal muscle. Nitric oxide donors may be a promising family of therapeutic agents for the prevention of ischemia-induced reperfusion injury in cutaneous and myocutaneous flaps.

A Quantitative Method for Determining Polarization of Neutrophil Adhesion Molecules Associated with Ischemia Reperfusion

Ischemia-reperfusion–induced neutrophil adhesion to endothelium is CD18-dependent, but information regarding polarity of CD18 adhesion molecules remains speculative. This study evaluated neutrophil adhesion using an in vitro cell adhesion assay and introduces a quantitative method of measuring CD18 membrane distribution using confocal microscopy. Neutrophils from normal animals were isolated from whole blood and incubated with plasma from rat gracilis muscle flaps with no ischemia and reperfusion (nonischemic control, n = 10) or 4 hours of ischemia and 90 minutes of reperfusion (ischemia/reperfusion, n = 10), on coverslips pretreated with and without (phosphate-buffered saline) soluble intercellular adhesion molecules. Coverslips without intercellular adhesion molecules represented a negative control (intercellular adhesion molecules were required for adhesion). Percent adherence to intercellular adhesion molecules was expressed as a ratio of adherent cells/total cells. CD18 polarization was assessed by staining neutrophils with fluorescein isothiocyanate–labeled anti-CD11b, followed by confocal microscopy and Z-stack analysis. Membrane-associated CD18 was expressed as fluorescence intensity units in three equal areas of the cell membrane. Capping was defined as twice as much fluorescence in 33 percent of the cell membrane as in the remaining 67 percent. Neutrophils exposed to ischemia and reperfusion plasma showed a significant increase in adhesion (0.8 ± 0.1 percent versus 16.7 ± 2.2 percent, p < 0.001) and CD18 polarization (6.2 ± 1.7 percent versus 43.9 ± 12.2 percent, p = 0.0206) compared with controls. This article describes an in vitro assay that reliably reproduces the neutrophil adhesion phenomenon associated with ischemia-reperfusion injury. Results from confocal microscopy allowed for quantitative estimation of membrane-associated receptor polarization.

Effect of liposuction on skin perfusion

Clinical reports of full-thickness skin necrosis have raised concern about the thermal and dermal ischemic effects of ultrasound-assisted liposuction. The purpose of this study was to evaluate skin perfusion in patients treated with ultrasound-assisted liposuction or suction-assisted liposuction. Patients (n = 75) were studied prospectively in the perioperative period surrounding their suction-assisted liposuction (31 patients) or ultrasound-assisted liposuction (64 patients). The laser Doppler flowmeter was used to monitor skin perfusion in the treated regions preoperatively, intraoperatively, and postoperatively at a series of time intervals. The effects of the anesthetic, wetting solution, and type of liposuction (suction-assisted liposuction or ultrasound-assisted liposuction) on skin perfusion were measured. Anesthetic induction significantly increased measured skin perfusion. Wetting solution infusion significantly decreased skin perfusion (-57.4 percent +/- 2.0) by 15 minutes postinfusion. Skin perfusion in the ultrasound-assisted liposuction group was significantly greater than that of the suction-assisted liposuction patients at 1 hour, 1 day, and 1 week postoperatively; however, by 2 to 5 weeks, no difference in skin perfusion was noted and skin perfusion had returned to preoperative levels in both groups. Although skin perfusion in the suction-assisted liposuction group was significantly lower than in the ultrasound-assisted liposuction group in the early postoperative period, no differences in skin perfusion between the groups were noted beyond 1 week postoperatively, suggesting that neither technique impairs perfusion.

Reperfusion-induced neutrophil CD18 polarization: effect of hyperbaric oxygen.

BACKGROUND Hyperbaric oxygen (HBO) inhibits ischemia reperfusion (IR) -induced neutrophil adhesion to endothelium through an unknown mechanism. This study evaluates the effect of HBO on IR-stimulated neutrophil adhesion and polarization of expressed CD18 adhesion molecules using a novel in vitro adhesion assay and confocal microscopy. MATERIALS AND METHODS Neutrophils from normal animals were isolated from whole blood and incubated with plasma from rat gracilis muscle flaps on coverslips pretreated with ICAM. Percent adherence to ICAM and CD18 polarization was evaluated in the following five groups: (1) Nonischemic control, n = 15; (2) 4 h ischemia (IR, n = 15); (3) 4 h ischemia with HBO treatment (100% oxygen at 2.5 atmospheres absolute (IR + HBO, n = 15)); (4) 4 h ischemia with 100% oxygen at room temperature and pressure (RTP) (IR + normobaric hyperoxia, n = 5); and (5) 4 h ischemia with 8% oxygen at 2.5 atmospheres absolute (IR + hyperbaric normoxia, n = 5). Direct HBO treatment of neutrophils was also evaluated. RESULTS Neutrophils exposed to IR plasma showed a significant increase in percent adherent (0.8 +/- 0.1% versus 16.7 +/- 2.2%, P < 0.05) and polarized cells (6.2 +/- 1.7% versus 43.9 +/- 12.2%, P < 0.05) compared to controls. Hyperbaric oxygen significantly reduced the adhesion and polarization to 1.6 +/- 0.3 and 4.1 +/- 2.5%, respectively (P = < 0.05). Normobaric hyperoxia and hyperbaric normoxia did not affect neutrophil adherence or CD18 polarization following IR. Direct HBO treatment of neutrophils did not change the percent of polarized cells in IR. CONCLUSIONS Hyperbaric oxygen inhibits IR-induced neutrophil adhesion by blocking CD18 surface polarization and requires plasma exposure to HBO. Treatment with oxygen or pressure alone is not effective.