Durable vision improvement after a single intravitreal treatment with antisense oligonucleotide in CEP290-LCA: Replication in two eyes.

Purpose: An intravitreally injected antisense oligonucleotide, sepofarsen, was designed to modulate splicing within retinas of patients with severe vision loss due to deep intronic c.2991 + 1655A > G variant in the CEP290 gene. A previous report showed vision improvements following a single injection in one eye with unexpected durability lasting at least 15 months. The current study evaluated durability of efficacy beyond 15 months in the previously treated left eye. In addition, peak efficacy and durability were evaluated in the treatment-naive right eye, and re-injection of the left eye 4 years after the first injection. Observations: Visual function was evaluated with best corrected standard and low-luminance visual acuities, microperimetry, dark-adapted chromatic perimetry, and full-field sensitivity testing. Retinal structure was evaluated with OCT imaging. At the fovea, all visual function measures and IS/OS intensity of the OCT showed transient improvements peaking at 3-6 months, remaining better than baseline at ∼2 years, and returning to baseline by 3-4 years after each single injection. Conclusions and Importance: These results suggest that sepofarsen reinjection intervals may need to be longer than 2 years.

Imposter Syndrome Relation to Gender Across Osteopathic Medical Schools.

This study explores the rate of Imposter Syndrome (IS) in osteopathic medical students specifically in regard to gender. Additionally, we compare IS with previous performance on the Medical College Admission Test (MCAT) and undergraduate science GPA. IS has been described as a psychological term that refers to a pattern of behavior wherein people doubt their abilities and have a persistent fear of being exposed as a fraud regardless of adequate external evidence of success. Females in professional fields have been shown to experience IS at a significantly higher rate than their male counterparts, the cause of which is unknown. We performed an anonymous survey distributed to osteopathic medical students in the USA from the classes of 2020-2023. The final data included information from 23 classes across 9 osteopathic medical schools. Students were asked eight questions from the Young Imposter Scale questionnaire to determine if a student had IS. Students were also asked to provide MCAT scores and undergraduate science GPA information. This study confirms that female osteopathic medical students experience IS at a higher rate than their male counterparts. This phenomenon is not dependent on gender ratios in medical school classes, nor is it dependent on previous student success on the MCAT or undergraduate science GPA. This indicates that medical schools need to be aware of IS throughout the student population, not just high-achieving individuals. IS is a significant problem in medical education, which can lead to physician burnout and deteriorating well-being.

A simple and rapid method for enzymatic synthesis of CRISPR-Cas9 sgRNA libraries.

CRISPR-Cas9 sgRNA libraries have transformed functional genetic screening and have enabled several innovative methods that rely on simultaneously targeting numerous genetic loci. Such libraries could be used in a vast number of biological systems and in the development of new technologies, but library generation is hindered by the cost, time, and sequence data required for sgRNA library synthesis. Here, we describe a rapid enzymatic method for generating robust, variant-matched libraries from any source of cDNA in under 3 h. This method, which we have named SLALOM, utilizes a custom sgRNA scaffold sequence and a novel method for detaching oligonucleotides from solid supports by a strand displacing polymerase. With this method, we constructed libraries targeting the E. coli genome and the transcriptome of developing zebrafish hearts, demonstrating its ability to expand the reach of CRISPR technology and facilitate methods requiring custom libraries.

Short-Wavelength Sensitive Cone (S-cone) Testing as an Outcome Measure for NR2E3 Clinical Treatment Trials.

Recessively-inherited NR2E3 gene mutations cause an unusual retinopathy with abnormally-increased short-wavelength sensitive cone (S-cone) function, in addition to reduced rod and long/middle-wavelength sensitive cone (L/M-cone) function. Progress toward clinical trials to treat patients with this otherwise incurable retinal degeneration prompted the need to determine efficacy outcome measures. Comparisons were made between three computerized perimeters available in the clinic. These perimeters could deliver short-wavelength stimuli on longer-wavelength adapting backgrounds to measure whether S-cone vision can be quantified. Results from a cohort of normal subjects were compared across the three perimeters to determine S-cone isolation and test-retest variability. S-cone perimetry data from NR2E3-ESCS (enhanced S-cone syndrome) patients were examined and determined to have five stages of disease severity. Using these stages, strategies were proposed for monitoring efficacy of either a focal or retina-wide intervention. This work sets the stage for clinical trials.

Microsurgical Reconstruction of the Burned Hand and Upper Extremity.

Improvements in critical care and burn victim resuscitation have led to increased survival of burned patients. Initial resuscitation, early excision of burned tissues, prevention of burn wound sepsis, and wound coverage remain mainstays of care. Many burn wounds require complex reconstruction. This is particularly important in the hand. Coverage of tendons, ligaments, joints, vessels, nerves, and bones of the hand requires healthy vascularized tissue to maintain viability and function. Local flaps or regional flaps may be within the burn zone of injury. Refined microvascular free tissue transfer techniques offer free tissue transfer as a procedure that can be safely performed.

Macular function in macular degenerations: repeatability of microperimetry as a potential outcome measure for ABCA4-associated retinopathy trials.

PURPOSE: To measure macular visual function in patients with unstable fixation, to define the photoreceptor source of this function, and to estimate its test-retest repeatability as a prerequisite to clinical trials. METHODS: Patients (n = 38) with ABCA4-associated retinal degeneration (RD) or with retinitis pigmentosa (RP) were studied with retina-tracking microperimetry along the foveo-papillary profile between the fovea and the optic nerve head, and point-by-point test-retest repeatability was estimated. A subset with foveal fixation was also studied with dark-adapted projection perimetry using monochromatic blue and red stimuli along the horizontal meridian. RESULTS: Macular function in ABCA4-RD patients transitioned from lower sensitivity at the parafovea to higher sensitivity in the perifovea. RP patients had the inverse pattern. Red-on-red microperimetric sensitivities successfully avoided ceiling effects and were highly correlated with absolute sensitivities. Point-by-point test-retest limits (95% confidence intervals) were ±4.2 dB; repeatability was not related to mean sensitivity, eccentricity from the fovea, age, fixation location, or instability. Repeatability was also not related to the local slope of sensitivity and was unchanged in the parapapillary retina. CONCLUSIONS: Microperimetry allows reliable testing of macular function in RD patients without foveal fixation in longitudinal studies evaluating natural disease progression or efficacy of therapeutic trials. A single estimate of test-retest repeatability can be used to determine significant changes in visual function at individual retinal loci within diseased regions that are homogeneous and those that are heterogeneous and also in transition zones at high risk for disease progression.

Retinal disease course in Usher syndrome 1B due to MYO7A mutations.

PURPOSE. To determine the disease course in Usher syndrome type IB (USH1B) caused by myosin 7A (MYO7A) gene mutations. METHODS. USH1B patients (n = 33, ages 2-61) representing 25 different families were studied by ocular examination, kinetic and chromatic static perimetry, dark adaptometry, and optical coherence tomography (OCT). Consequences of the mutant alleles were predicted. RESULTS. All MYO7A patients had severely abnormal ERGs, but kinetic fields revealed regional patterns of visual loss that suggested a disease sequence. Rod-mediated vision could be lost to different degrees in the first decades of life. Cone vision followed a more predictable and slower decline. Central vision ranged from normal to reduced in the first four decades of life and thereafter was severely abnormal. Dark adaptation kinetics was normal. Photoreceptor layer thickness in a wide region of central retina could differ dramatically between patients of comparable ages; and there were examples of severe losses in childhood as well as relative preservation in patients in the third decade of life. Comparisons were made between the mutant alleles in mild versus more severe phenotypes. CONCLUSIONS. A disease sequence in USH1B leads from generally full but impaired visual fields to residual small central islands. At most disease stages, there was preserved temporal peripheral field, a potential target for early phase clinical trials of gene therapy. From data comparing patients' rod disease in this cohort, the authors speculate that null MYO7A alleles could be associated with milder dysfunction and fewer photoreceptor structural losses at ages when other genotypes show more severe phenotypes.

Epicondylectomy versus denervation for lateral humeral epicondylitis.

BACKGROUND: Traditional management of lateral humeral epicondylitis ("tennis elbow") relies upon antiinflammatory medication, rehabilitation, steroid injection, counterforce splinting, and, finally, surgery to the common extensor origin. The diversity of surgical approaches for lateral humeral epicondylitis (LHE) suggests perhaps that the ideal technique has not been determined. Denervation of the lateral humeral epicondyle is the concept of interrupting the neural pathway that transmits the pain message. Epicondylectomy may accomplish its relief of LHE by denervating the epicondyle. METHODS: Since it is known that the posterior branch of the posterior cutaneous nerve of the forearm innervates the lateral humeral epicondyle, 30 patients who were treated surgically for refractory LHE were retrospectively evaluated. Group 1 consisted of 17 patients who were treated with epicondylectomy alone, group II consisted of seven patients who were treated with lateral epicondylectomy plus neurectomy, and group III consisted of seven patients treated with lateral denervation alone. RESULTS: Denervation alone gave statistically significantly greater improvement in pain relief (p < 0.001) and statistically significantly faster return to work than did epicondylectomy alone (p < 0.001). Denervation plus epicondylectomy gave results that were the same as denervation alone. CONCLUSION: It is concluded that denervation gives significant relief from LHE once traditional non-surgical treatment has failed.

Closed Zone III Rupture of the Flexor Digitorum Profundus Tendons of the Right Index, Long, and Ring Fingers in a Bowler: Gutterball Syndrome.

Zone III flexor tendon injuries are relatively rare in comparison to other flexor tendon injuries in zones I, II, IV, and V. Often, these are open injuries resulting from an electrical device like a saw; however, closed injures are even rarer, and those mid-substance ruptures resulting from bowling with no evidence of underlying tendinopathy from diseases like gout are highly unusual. The principles underlying tendon repair remain the same regardless of the etiology. In this case, we delineate some of the options and stress the guiding principles of the various methods available in this interesting and unusual case.

CERKL mutations cause an autosomal recessive cone-rod dystrophy with inner retinopathy.

PURPOSE: To define the phenotype of the retinal degeneration associated with mutations in the CERKL gene. METHODS: Six patients (ages, 26-54 years) from three unrelated families with CERKL mutations were studied clinically and by electroretinography, kinetic, and chromatic static perimetry, autofluorescence (AF) imaging, and optical coherence tomography (OCT). RESULTS: Three siblings were homozygotes for p.R257X mutation; two siblings were compound heterozygotes for p.R257X and a novel p.C362X mutation; and one patient had only p.R257X mutation identified to date. There was a spectrum of severity: from mild visual acuity loss to light perception; from full kinetic fields with relative central scotomas to remnant peripheral islands; from reduced ERGs (some with negative waveforms) to nondetectable signals. Maculopathy showed residual foveal islands or extensive central rod and cone scotomas. With AF imaging, there was evidence of hyperautofluorescence at earlier and hypoautofluorescence at later disease stages. Peripheral function was generally less affected than central function. With OCT there were small foveal islands of outer nuclear layer (ONL) in those with preserved acuity. Eccentric to an annular region with no discernible ONL, there could be ONL in the midperiphery. At early disease stages, ganglion cell layer thickness was less affected than ONL. Later disease stages were accompanied by inner nuclear layer and nerve fiber layer abnormalities. CONCLUSIONS: CERKL mutations are associated with widespread retinal degeneration with prominent maculopathy. The clinical presentation is that of an autosomal recessive cone-rod dystrophy. Photoreceptor loss appears at all stages of disease and inner laminopathy complicates the phenotype at later stages.

Replantation outcomes.

Replantation aims to restore the amputated part to its anatomical site, preserving function and appearance. Outcome depends on factors intrinsic to the patient and to the nature of the injury. Young patients who have distal, cleanly amputated extremities have the best return of function; multiple levels of injury, crush, or avulsing injuries have less. Patients must be fully informed about the commitment to rehabilitation and the possibility of multiple surgeries needed for best results. Similarly, patient and surgeon expectations should be evaluated and addressed before replantation. Meticulous microsurgical technique, comprehensive occupational therapy, and perseverance are needed for success. Addressing these issues promotes a team rehabilitation to restore function while getting the amputation patient back to productive position in society.

Extremity reconstruction using nonreplantable tissue ("spare parts").

After a severe digital or extremity injury, the replantation surgeon should always seek to make the best use out of what tissue is available for reconstruction. Exercising sound surgical judgment and being creative allow the surgeon to restore function to critical areas of the hand or extremity by the judicious use of available tissues that would otherwise be discarded. The use of "spare parts" should, therefore, always be considered to facilitate digital or extremity reconstruction when routine replantation is not possible or is likely to produce a poor functional result. The surgeon should always try to use available nonreplantable tissue to preserve length, obtain soft tissue coverage, or most importantly improve the function of remaining less injured digits. This article presents several case studies that illustrate the principals of spare parts reconstruction performed at the time of the initial debridement using nonreplantable tissue to provide coverage or improve function.

Tissue engineering: bridging the gap between replantation and composite tissue allografts.

This article explores issues related to tissue engineering and composite tissue allografts that employ physiologic and anatomic autogenous replicates to restore tissue loss. Composite tissue allotransplantation has become a controversial option for reconstruction, most prominently for reconstruction involving the hand and, recently, the face. While the side-effect profile of systemic immunosuppression continues to improve, the long-term risks of immunosuppression leaves composite tissue allotransplantation a domain for cautious exploration. Meanwhile, tissue engineering could, conceivably, be the gap between replantation and composite tissue allografts. Whereas the perils of immunosuppression may limit the routine use of allografts, employing constructions made of the patient's own cells negates the need for any antirejection therapy.

The "pixie" ear deformity following face lift surgery revisited.

BACKGROUND: The "pixie" ear deformity can be recognized by its "stuck on" or "pulled" appearance, which is caused by the extrinsic pull of the medial cheek and jawline skin flaps at the earlobe attachment point, the otobasion inferius. The tension results in migration of the otobasion inferius from a posterior cephalad position to an anterior caudal position. Although this deformity has been described clinically, it has yet to be objectively defined. METHODS: Recently, the two components of the earlobe, the attached cephalic segment (intertragal to otobasion inferius distance) and the free caudal segment (otobasion inferius to subaurale distance), were shown to be essential in evaluating for earlobe ptosis and pseudoptosis. These two components can be used to designate an objective criterion for the pixie ear deformity. The deformity, as defined by the authors' parameters, was assessed in 44 patients who had undergone rhytidectomy. A simple and accurate surgical treatment is demonstrated by a cadaver dissection and a clinical case. RESULTS: The deformity can be defined as an increase in the attached cephalic segment (intertragal to otobasion inferius distance) and a decrease in the free caudal segment (otobasion inferius to subaurale distance) to 0 mm following rhytidectomy. The incidence of pixie ear deformity was 5.7 percent in the authors' series of patients. CONCLUSIONS: A medially based triangular excision over the attached cephalic segment is presented as a simple and accurate surgical treatment of pixie ear deformity. A more accurate and objective designation may allow for improved detection, avoidance, and treatment of this deformity.

Anomalous flexor digitorum superficialis muscle transposition for vascular coverage of the median nerve in recurrent carpal tunnel syndrome.

Recurrent carpal tunnel syndrome is uncommon yet troublesome. Significant adhesions and scarring around the median nerve can render it relatively ischemic. A number of vascular flaps have been described to provide vascular coverage in attempts to decrease further cicatricial adhesions and to improve local blood supply around the median nerve. A rare case of an anomalous muscle in the distal forearm used as tissue to provide good vascularized coverage of the median nerve that was severely scarred in its bed is reported. The anomalous muscle was distal to the flexor digitorum superficialis tendon and inserted in the palmar fascia on the ulnar aspect of the hand. Referring branches from the ulnar artery provided vascular supply to the anomalous muscle. The muscle on these vascular pedicles was transposed over the median nerve, providing good, stable, unscarred coverage. The patient had an excellent result with resolution of the carpal tunnel symptoms. The redundant anomalous muscle provided a unique vascularized source for coverage of the median nerve in recurrent carpal tunnel syndrome.

La récidive du syndrome du tunnel carpien est un phénomène rare, mais ennuyeux. La formation d'adhésions et de tissu cicatriciel importants autour du nerf médian peut rendre ce dernier relativement ischémique. Un certain nombre de lambeaux ont été décrits pour assurer la couverture vasculaire et réduire les adhésions cicatricielles et améliorer ainsi l'irrigation sanguine locale autour du nerf médian. On décrit ici un cas rare de transposition d'un muscle de l'avant-bras distal pour fournir une bonne vascularisation du tendon médian gravement cicatrisé. Le muscle était situé à la portion distale du tendon du flexor digitorum superficialis et inséré dans l'aponévrose palmaire de la portion cubitale de la main. Les branches de l'artère cubitale ont fourni l'irrigation vasculaire vers le muscle greffé. Le muscle chevauchant ces pédoncules vasculaires a été transposé sur le nerf médian, lui offrant une bonne couverture, stable et non cicatrisée. La patiente a obtenu d'excellents résultats avec résolution de ses symptômes. La greffe musculaire a constitué une source hors pair de vascularisation du nerf médian dans ce cas de récidive de syndrome du tunnel carpien.

Surgical design and algorithm for correction of earlobe ptosis and pseudoptosis deformity.

A previously described classification system for earlobe ptosis and criterion for earlobe pseudoptosis deformity was based on height measurements of the two earlobe components: the free caudal segment and the attached cephalic segment. The "ideal" ear lobule free caudal segment was found to be between 1 and 5 mm (grade I ptosis), and the "ideal" attached cephalic segment was 15 mm or less. Earlobe pseudoptosis was defined by an attached cephalic segment measuring greater than 15 mm. Previous studies revealed an association between the elongated free caudal segment and increasing patient age and between the elongated attached cephalic segment and rhytidectomy. Sixteen fresh cadaver earlobes were used to design surgical patterns that would differentially reduce the free caudal segment, the attached cephalic segment, or both. A horizontal, medially based triangular excision pattern was designed. Triangular excisions limited to the attached cephalic segment resulted in 98 +/- 5 percent reduction of excision height from the attached cephalic segment but also resulted in an unexpected 32 +/- 2 percent augmentation of the excision height in the free caudal segment. Triangular excisions limited to the free caudal segment resulted in 88 +/- 4 percent reduction of the excision height from the free caudal segment and negligible reduction of 4 +/- 4 percent of excision height in the cephalic attached segment. An algorithm for correction of earlobe ptosis and pseudoptosis was subsequently derived and implemented in a clinical case. The authors propose that surgical treatment of patients with pseudoptosis be dependent on the ptosis grade. If the ptosis is grade I (1 to 5 mm), then excision of only the attached cephalic segment is recommended. If the ptosis is grade II or higher (more than 5 mm), then a combined attached cephalic and free caudal segment excision is recommended. In cases of isolated ptosis grade II or higher without pseudoptosis, then excision location of only the free caudal segment is recommended. The above simple algorithm and surgical designs will enable plastic surgeons to differentially correct earlobe ptosis and pseudoptosis.

Capsule induction technique in a rat model for bladder wall replacement: an overview.

The search for a reliable technique for functional genitourinary tissue replacement remains a challenging task. The most recent advances in cell biology and tissue engineering have utilized various avascular and acellular collagen scaffolds with or without seeded cells. These techniques, however, are frequently complicated by tissue necrosis, contracture and resorption due to limited vascularization. We employed a new three-stage, evolving animal model with stage I optimizing the culture delivery vehicle, stage II employing a seeded vascularized capsule flap, and stage III adding a contractile matrix in the form of pedicled gracilis muscle prelaminated with autologous, in vitro-expanded urothelial cells to reconstruct an entire supratrigonal bladder-wall defect in rats.Specimens stained with hematoxylin and eosin (H&E), alpha(1)-actin staining, and a specific immunohistochemical staining (AE(1)&AE(3)-anticytoceratin monoclonal antibody stain) showed a continuous, multilayered, functioning urothelial lining along the transposed prelaminated gracilis flap in the animals of the final-stage experiment. Successful urinary reconstruction requires a contractile neoreservoir resistant to resorption over time and a stable, protective urothelial lining. We demonstrated that a gracilis muscle flap can be seeded with autologous cultured urothelial cells suspended in fibrin glue. This prelaminated flap can be safely transposed onto its pedicle and become successfully integrated into the remaining bladder wall, demonstrating urothelial lining and the potential to contract. Further studies in larger animals with urodynamic assessment is warranted to determine if this type of bladder-wall replacement technique is suitable for urinary reconstruction in humans.

Age-related differences of neutrophil activation in a skeletal muscle ischemia-reperfusion model.

Free tissue transfers and replantation of amputated limbs are better tolerated by young adolescents than mature adults. The authors hypothesized that this observation may be, in part, because of an attenuated ischemia-reperfusion (IR) injury in younger patients. Because neutrophils have been identified as a critical cell line responsible for IR injury, the authors investigated the effects of animal age on the degree of neutrophil activation in a rat model. Activation was evaluated by monitoring expression of integrin surface markers (mean fluorescence intensity [MFI] of CD11b) and oxidative burst potential (MFI of dihydrorhodamine [DHR] oxidation) by flow cytometry in neutrophils analyzed after 4 hours of ischemia and 1, 4, and 16 hours of reperfusion in a gracilis muscle flap model in mature adult and young adolescent rats. Neutrophil activation was also evaluated in control sham-operated animals, which underwent elevation of gracilis muscle flaps without exposure to an ischemic insult. Muscle edema, determined by wet-to-dry muscle weight ratio, and muscle viability, determined by nitro blue tetrazolium (NBT) staining, were completed for gracilis muscles exposed to ischemia after 24 hours of reperfusion for each of the groups. Integrin expression, assessed by MFI of CD11b, was increased significantly in ischemic muscles of mature adult rats at 4 hours of reperfusion (71.10+/-3.53 MFI vs. 54.88+/-12.73 MFI, p=0.025). Neutrophil oxidative potential, assessed by MFI of DHR oxidation, was increased significantly in ischemic muscles of mature adult rats compared with young adolescent rats at 1 hour of reperfusion (78.10+/-9.53 MFI vs. 51.78+/-16.91 MFI, p=0.035) and 4 hours of reperfusion (83.69+/-15.29 MFI vs. 46.55+/-8.09 MFI, p=0.005). Increased edema formation was observed in the ischemic muscles of mature adult rats when compared with young adolescent rats (1.25+/-0.04 vs. 1.12+/-0.05, p=0.031) after 24 hours of reperfusion. A trend toward decreased muscle viability was observed in the mature adult rats when compared with young adolescent rats (23.7+/-3.1% NBT staining vs. 32.3+/-13.7% NBT staining, p=0.189) after 24 hours of reperfusion. The authors present evidence of an attenuated IR injury in young adolescent animals when compared with mature adult rats. These findings emphasize the importance that studies involving IR injury should be performed with consideration of animal age.

Secondary procedures following mutilating hand injuries.

Mutilating hand injuries result in injury to multiple anatomic structures, which increases the possibility that secondary procedures or staged reconstruction will be necessary. Secondary procedures often are required to provide stable wound coverage, restore sensation, provide bony stability, increase range of motion, or allow prehension, all of which are performed to improve hand function. The patient, the surgeon, and the therapist must all work together to achieve the best functional result following a severe mutilating hand injury.

Local hypothermia during early reperfusion protects skeletal muscle from ischemia-reperfusion injury.

Amputated tissue maintained in a hypothermic environment can endure prolonged ischemia and improve replantation success. The authors hypothesized that local tissue hypothermia during the early reperfusion period may provide a protective effect against ischemia-reperfusion injury similar to that seen when hypothermia is provided during the ischemic period. A rat gracilis muscle flap model was used to assess the protective effects of exposing skeletal muscle to local hypothermia during ischemia only (p = 18), reperfusion only (p = 18), and both ischemia and reperfusion (p = 18). Gracilis muscles were isolated and exposed to hypothermia of 10 degrees C during 4 hours of ischemia, the initial 3 hours of reperfusion, or both periods. Ischemia-reperfusion outcome measures used to evaluate muscle flap injury included muscle viability (percent nitroblue tetrazolium staining), local edema (wet-to-dry weight ratio), neutrophil infiltration (intramuscular neutrophil density per high-power field), neutrophil integrin expression (CD11b mean fluorescence intensity), and neutrophil oxidative potential (dihydro-rhodamine oxidation mean fluorescence intensity) after 24 hours of reperfusion. Nitroblue tetrazolium staining demonstrated improved muscle viability in the experimental groups (ischemia-only: 78.8 +/- 3.5 percent, p < 0.001; reperfusion-only: 80.2 +/- 5.2 percent, p < 0.001; and ischemia-reperfusion: 79.6 +/- 7.6 percent, p < 0.001) when compared with the nonhypothermic control group (50.7 +/- 9.3 percent). The experimental groups demonstrated decreased local muscle edema (4.09 +/- 0.30, 4.10 +/- 0.19, and 4.04 +/- 0.31 wet-to-dry weight ratios, respectively) when compared with the nonhypothermic control group (5.24 +/- 0.31 wet-to-dry weight ratio; p < 0.001, p < 0.001, and p < 0.001, respectively). CD11b expression was significantly decreased in the reperfusion-only (32.65 +/- 8.75 mean fluorescence intensity, p < 0.001) and ischemia-reperfusion groups (25.26 +/- 5.32, p < 0.001) compared with the nonhypothermic control group (62.69 +/- 16.93). There was not a significant decrease in neutrophil CD11b expression in the ischemia-only group (50.72 +/- 11.7 mean fluorescence intensity, p = 0.281). Neutrophil infiltration was significantly decreased in the reperfusion-only (20 +/- 11 counts per high-power field, p = 0.025) and ischemia-reperfusion groups (23 +/- 3 counts, p = 0.041) compared with the nonhypothermic control group (51 +/- 28 counts). No decrease in neutrophil density was observed in the ischemia-only group (40 +/- 15 counts per high-power field, p = 0.672) when compared with the nonhypothermic control group (51 +/- 28 counts). Finally, dihydrorhodamine oxidation was significantly decreased in the reperfusion-only group (45.83 +/- 11.89 mean fluorescence intensity, p = 0.021) and ischemia-reperfusion group (44.30 +/- 11.80, p = 0.018) when compared with the nonhypothermic control group (71.74 +/- 20.83), whereas no decrease in dihydrorhodamine oxidation was observed in the ischemia-only group (65.93 +/- 10.3, p = 0.982). The findings suggest a protective effect of local hypothermia during early reperfusion to skeletal muscle after an ischemic insult. Inhibition of CD11b expression and subsequent neutrophil infiltration and depression of neutrophil oxidative potential may represent independent protective mechanisms isolated to local tissue hypothermia during the early reperfusion period (reperfusion-only and ischemia-reperfusion groups). This study provides evidence for the potential clinical utility of administering local hypothermia to ischemic muscle tissue during the early reperfusion period.