Dual Orbital Degeneracy Lifting in a Strongly Correlated Electron System.

The local structure of NaTiSi_{2}O_{6} is examined across its Ti-dimerization orbital-assisted Peierls transition at 210 K. An atomic pair distribution function approach evidences local symmetry breaking preexisting far above the transition. The analysis unravels that, on warming, the dimers evolve into a short range orbital degeneracy lifted (ODL) state of dual orbital character, persisting up to at least 490 K. The ODL state is correlated over the length scale spanning ∼6 sites of the Ti zigzag chains. Results imply that the ODL phenomenology extends to strongly correlated electron systems.

Robust Phonon-Plasmon Coupling in Quasifreestanding Graphene on Silicon Carbide.

Using inelastic electron scattering in combination with dielectric theory simulations on differently prepared graphene layers on silicon carbide, we demonstrate that the coupling between the 2D plasmon of graphene and the surface optical phonon of the substrate cannot be quenched by modification of the interface via intercalation. The intercalation rather provides additional modes like, e.g., the silicon-hydrogen stretch mode in the case of hydrogen intercalation or the silicon-oxygen vibrations for water intercalation that couple to the 2D plasmons of graphene. Furthermore, in the case of bilayer graphene with broken inversion symmetry due to charge imbalance between the layers, we observe a similar coupling of the 2D plasmon to an internal infrared-active mode, the LO phonon mode. The coupling of graphene plasmons to vibrational modes of the substrate surface and internal infrared active modes is envisioned to provide an excellent tool for tailoring the plasmon band structure of monolayer and bilayer graphene for plasmonic devices such as plasmon filters or plasmonic waveguides. The rigidity of the effect furthermore suggests that it may be of importance for other 2D materials as well.

Local orbital degeneracy lifting as a precursor to an orbital-selective Peierls transition.

Fundamental electronic principles underlying all transition metal compounds are the symmetry and filling of the d-electron orbitals and the influence of this filling on structural configurations and responses. Here we use a sensitive local structural technique, x-ray atomic pair distribution function analysis, to reveal the presence of fluctuating local-structural distortions at high temperature in one such compound, CuIr2S4. We show that this hitherto overlooked fluctuating symmetry-lowering is electronic in origin and will modify the energy-level spectrum and electronic and magnetic properties. The explanation is a local, fluctuating, orbital-degeneracy-lifted state. The natural extension of our result would be that this phenomenon is likely to be widespread amongst diverse classes of partially filled nominally degenerate d-electron systems, with potentially broad implications for our understanding of their properties.

Access to the superior mediastinum.

Surgical access for diseases that involve the superior mediastinum can be achieved without thoracotomy by utilizing the suprasternal approach with extension of the head and neck and transection of the interclavicular ligament, median sternotomy, resection of the medial third to one half of the clavicle, or resection of the manubrium sterni. There has been minimal morbidity and no operative or postoperative mortality in a review of 53 consecutive patients. There has been no significant disability. Combined with exposure at the base of the neck, the access to the superior mediastinum is good to excellent.

Anatomic correlates of normal and diseased adenoids in children.

In order to better understand the pathogenesis and sequelae of obstructive adenoid hyperplasia in children, the anatomic relationships of the adenoids to the hard and soft palates, oropharynx, and nasopharynx were studied in vivo in 94 children. Direct, intraoperative palatal, nasopharyngeal, and oropharyngeal measurements were performed in 19 children with normal, nondiseased adenoids (controls [C]) and compared to 75 children undergoing adenoidectomy for obstructive adenoid hyperplasia (OAH) (n = 44) or chronic adenoid infection (CAI) (n = 31). As expected, the weight and volume of the adenoids removed were significantly greater in the OAH vs. CAI group (P < .001). Before adenoidectomy, the volume of the nasopharynx was significantly smaller in the OAH group; however, nasopharyngeal volumes after adenoidectomy were quite similar in all three groups and ranged from 5.4 to 6.2 cc. Only the change in the volume of the nasopharynx after adenoidectomy for obstruction was significant (2.5 +/- 1.2 cc, P < .01). Differences in oropharyngeal and palatal dimensions were not associated with longstanding obstruction from adenoid hyperplasia. These data indicate that the nasal obstruction from adenoid hyperplasia is due to an absolute increase in adenoid size rather than a relatively smaller nasopharynx. Differences in palatal and oropharyngeal dimensions usually described and attributed to longstanding nasal obstruction could not be demonstrated in this study.

Qualitative and quantitative immunoglobulin production by specific bacteria in chronic tonsillar disease.

Tonsillar tissue lymphocyte (TTL) function as measured by immunoglobulin production was assessed in vitro in 60 tonsils, 51 diseased and 9 normal controls. The diseased specimens were from children (aged 3 to 10 years) clinically classified as having recurrent tonsillitis (RT), idiopathic tonsillar hyperplasia (ITH), or recurrent tonsillitis with hyperplasia (RT/H). TTLs were challenged with intact, heat-inactivated bacteria found in the core of diseased tonsils--Streptococcus pyogenes (SP) and Haemophilus influenzae type B (HIB) as well as the dominant bacterium (DB) grown from that particular tonsillar core. The phytomitogen, leukoagglutinin (LA), was used as a nonspecific activator. Qualitative immunoglobulin production was assessed for the immunoglobulin G (IgG), immunoglobulin M (IgM), and immunoglobulin A (IgA) classes. Immunoglobulin-specific production was quantified at the basal level, and at 2, 4, and 6 days following stimulation. Stimulation with HIB produced the greatest amount of IgG and IgM in TTLs from control tonsils. The DB was a relatively weak stimulator of normal (control) TTLs, yet produced relatively brisk IgG responses in the RT and ITH categories. It did, however, yield only marginal IgM secretion in these groups. IgA was consistently produced after stimulation in diseased TTLs, yet was not elicited from normal TTLs. The aforementioned findings suggest a differential qualitative and quantitative immunoglobulin response for healthy, recurrently infected, and hyperplastic tonsils. Lymphocyte hypofunction along with structural changes associated with hyperplasia may be central to the etiology of chronic tonsillar disease. The tonsillar immunologic response in disease and health is discussed.

Effect of specific bacteria on lymphocyte proliferation in diseased and nondiseased tonsils.

Tonsillar tissue lymphocyte (TTL) function as measured by lymphocyte proliferation was assessed in vitro in 38 tonsils--30 diseased and 8 normal controls. TTLs from diseased and control tonsils were challenged with intact, heat-inactivated bacteria which may be found in the core of diseased tonsils; these bacteria were Streptococcus pyogenes and Hemophilus influenzae type B (HIB), as well as the dominant bacterium (DB) grown from that particular tonsillar core. The phytomitogen leukoagglutinin (LA) was used as a nonspecific activator. Lymphocyte proliferation was quantified and reported using a stimulation index (SI) which was based upon viable cell counts at 2, 4, and 6 days following inoculation. Overall, the greatest degree of lymphocyte proliferation in diseased TTLs (SI = .91) was produced by HIB. However, both SP and HIB produced more lymphocyte proliferation in the nondiseased TTLs than in the diseased TTLs (P < .01). H influenzae (non-B) and group A beta-hemolytic streptococci were the pathogens most frequently cultured as the dominant bacteria from the core of diseased tonsils; Streptococcus viridans was most frequently cultured in nondiseased tonsils. The DB caused greater TTL proliferation in diseased (SI = .89) versus control (SI = .63) TTLs (P < .001). These findings suggest a differential proliferative response in vitro for diseased and nondiseased TTLs in response to specific bacteria. The role of possibly pathogenic bacteria and commensals, as well as the implications for clinical disease, are discussed.

Contemporary management of the aging brow and forehead.

Management of the aging brow and forehead has recently evolved based on available innovative technologies. Likewise, procedure-specific indications have changed based on collective surgical experiences. No longer is the approach based solely on hair pattern or degree of brow ptosis. Patients require varying combinations of brow elevation (prior to blepharoplasty), correction of brow asymmetries, and hairline-preserving forehead elevation. Some may only require excisional or paralytic procedures of the frontalis muscle (horizontal forehead creases), corrugator supercilii muscles (vertical glabellar furrows), and procerus muscle (horizontal glabellar furrows). We present a 3-year experience using a problem-specific approach. This incorporates endoscopic technology, botulinum toxin type A purified neurotoxin complex (Botox, Allergan, Irvine, CA) intramuscular injection, and traditional procedures such as the coronal, pretrichial, midforehead, and direct browlift. Current indications, patient selection, and results are also discussed.

The failing flap in facial plastic and reconstructive surgery: role of the medicinal leech.

OBJECTIVE: To review the use of the medicinal leech, Hirudo medicinalis, in salvaging the failing, venous-congested flap. A protocol for the use of leeches is presented. Four illustrative cases of failing flaps (pectoralis major, midline forehead, and temporalis) are presented. STUDY DESIGN: Literature review comprised of MEDLINE search 1965 to present. Retrospective review of four cases involving the management of the failing, venous-congested flap. METHODS: A retrospective review of four cases of failing, venous-congested flaps was performed. RESULTS: The authors' experience, as well as the data from the reviewed medical literature, demonstrates the importance of early intervention in order to salvage the failing, venous-congested flap. Leeches are an immediate and efficacious treatment option. CONCLUSIONS: 1. Review of the literature indicates that the survival of the compromised, venous-congested flap is improved by early intervention with the medicinal leech. H medicinalis injects salivary components that inhibit both platelet aggregation and the coagulation cascade. The flap is decongested initially as the leech extracts blood and is further decongested as the bite wound oozes after the leech detaches. 2. When a flap begins to fail, salvage of that flap demands early recognition of reversible processes, such as venous congestion. The surgeon must be familiar with the use of leeches and should consider their use early, since flaps demonstrate significantly decreased survival after 3 hours if venous congestion is not relieved. In the four cases presented, a standardized protocol facilitated early leech use and provided for the psychological preparation of the patient, availability of leeches, and an antibiotic prophylaxis regimen. 3. The complications associated with leech use can be minimized with antibiotic therapy, wound care, and hematocrit monitoring. 4. The use of the medicinal leech for salvage of the venous-congested flap is a safe, efficacious, economical, and well-tolerated intervention.

Direct bonded orthodontic brackets for maxillomandibular fixation.

OBJECTIVES/HYPOTHESIS: Mandibular fracture treatment often includes arch bar maxillomandibular fixation (MMF), either alone or in combination with open reduction/internal fixation (ORIF) techniques. The glove perforation rate associated with arch bar placement, the incidence of blood-borne pathogen positivity in facial fracture patients, and the injurious effects of arch bars on dental enamel and gingiva have prompted the development of safer alternatives to arch bar MMF. This study evaluates the efficacy, ease of use, and safety profile of one such alternative: orthodontic direct bonded bracket fixation (MMF/DBB). STUDY DESIGN: Prospective study of consecutive mandible fracture patients treated with MMF/DBB. METHODS: Thirty-two patients with mandibular fractures were evaluated from January 1994 to July 1997. Fourteen were appropriate for treatment with MMF/DBB (12 men and two woman; mean age, 24.6+/-7.2 y; range, 16-42 y). Fracture sites included symphysis, angle, condylar neck, coronoid, and body. Nine patients underwent MMF/DBB alone; five underwent MMF/DBB with subsequent ORIF. RESULTS: No infection, malocclusion, malunion/nonunion, or enamel/ gingiva injury occurred. Mean follow-up was 6 months (range, 1-12 mo). Oral hygiene with MMF/DBB was superior to historical controls using arch bars. CONCLUSIONS: MMF/DBB can serve as the single treatment method with satisfactory results in patients with favorable, less complicated mandible fractures, although with increased experience, we have treated several more complex cases with MMF/DBB alone. In cases necessitating ORIF, MMF/DBB can be performed preoperatively to align fracture segments and reestablish occlusion. This facilitates placement of osteosynthesis plates and reduces ORIF operative time. MMF/DBB is an economical, safe technique that minimizes blood-borne-pathogen risk to the operative team, eliminates periodontal injury, facilitates postoperative dental hygiene, and is painless to apply and remove.

Bacteriology and immunology of normal and diseased adenoids in children.

Adenoid physiology as reflected in the qualitative and quantitative bacteriology and immune cell distribution was correlated with clinical presentation in 69 children (16 to 130 months of age) undergoing adenoidectomy for obstructive adenoid hyperplasia (n = 38) or chronic adenoid infection (n = 31) and in 16 adenoid core biopsy specimens from 16 nondiseased controls. In the control adenoids, few potentially pathogenic bacteria were found as the dominant bacteria in the adenoid core (25%), and significantly greater concentrations of nonpathogens (commensals) were isolated (P < .01). Potential pathogens as the dominant bacteria were found twice as often in obstructive adenoid hyperplasia (62%) and in chronic adenoid infection (55%) (P < .05). Haemophilus influenzae was most common in the diseased adenoids, 53% in obstructive adenoid hyperplasia and 48% in chronic adenoid infection, compared with only 19% in the controls (P < .05). No significant differences in lymphocyte density, B and T cells, as well as T-helper subsets, were found between clinical classifications. However, T-suppressor cells, monocytes-macrophages, and natural killer cells were significantly increased in chronic adenoid infection only (P < .05). The findings in this study support roles for both alterations in bacterial homeostasis and an altered immune profile in the etiology of chronic adenoid disease in children.

Growth of tissue-engineered human nasoseptal cartilage in simulated microgravity.

OBJECTIVE: To evaluate the feasibility of in vitro fabrication of tissue-engineered cartilage from human nasoseptal chondrocytes for autologous reconstruction. DESIGN: Hyaline cartilage was reconstituted from chondrocyte-polyglycolic acid scaffolding constructs in a 3-dimensional mammalian cell culture cascade. This included monolayer cellular amplification, cell seeding in the spinner flask, and tissue growth in simulated microgravity. RESULTS: The quality of the fabricated cartilage analogue was found to depend on the initial cell density, duration of incubation, and bioreactor type. Dynamic seeding was nearly completed within the first 10 hours of inoculation regardless of the cell source (cryogenically preserved vs fresh chondrocytes) or presence of serum. A duration of incubation in excess of 4 weeks was required for complete matrix biosynthesis at low seeding densities in the spinner flasks. Seeding densities greater than 2.3x10(6) chondrocytes per scaffold were required for early hyaline cartilage formation as well as longer-time mature matrix regeneration. In addition, maintaining the structural integrity of the unreinforced scaffold, which is necessary for continued mature matrix regeneration, was achievable through postseeding tissue growth in simulated microgravity. CONCLUSION: Once combined with polyglycolic acid scaffolds in the bioreactor cascades that allow efficient seeding and quiescent tissue growth, human septal chondrocytes become a valuable source of reproducible ex vivo cartilage regeneration in the laboratory.

Basic fibroblast growth factor and insulinlike growth factor I support the growth of human septal chondrocytes in a serum-free environment.

OBJECTIVE: To determine if insulinlike growth factor I (IGF-I) and basic fibroblast growth factor (bFGF), individually or in combination, support the growth and viability of human septal chondrocytes in a serum-free medium (SFM) and a serum-enhanced culture medium. DESIGN: Chondrocytes were recovered from enzymatically digested human septal cartilage and were plated for monolayer culture in a newly developed medium. The medium included Dulbecco modified Eagle medium mixed 1:1 with Ham F12 medium and a supplement of known amounts of 2 growth factors-bFGF (100 ng/mL) and IGF-I (100 ng/mL)-used in combination and separately. RESULTS: The combination of IGF-I and bFGF enhanced chondrocyte growth and maintained a high degree of viability in SFM and 10% fetal calf serum. After an initial lag, the SFM, augmented with both growth factors, produced a comparable number of viable cells (4.25+/-0.31 x 10(4)) to that of the medium with 10% fetal calf serum (4.64+/-0.35 x 10(4)) by the seventh day of the experiment. Combined with the 2 growth factors, 10% fetal calf serum provided the greatest proliferation by the end of the experiment. However, the overall mean cell counts for the IGF-I- and bFGF-enhanced SFM were not statistically different. CONCLUSIONS: The combination of IGF-I and bFGF in a serum-free and a serum-supplemented environment supports the growth and viability of human septal chondrocytes in short-term culture. In an SFM, the results obtained approximate those produced in a medium enhanced with 10% fetal calf serum.

Combined use of superpulsed carbon dioxide laser and cryotherapy for treatment of facial rhytids.

OBJECTIVE: To compare the effect of superpulsed carbon dioxide (CO2) laser alone with that of cryotherapy in combination with CO2 laser in treatment of facial rhytids. DESIGN: A randomized prospective study. SETTING: Facial Plastic Surgery Clinic at Standford University Medical Center, Standford, Calif. PATIENTS: Twenty patients with perioral rhytids were randomized in the study, 11 in the laser group and 9 in the cryotherapy and laser group. INTERVENTION: Patients in the laser group were treated with superpulsed CO2 laser. Initially, the shoulders of rhytids were spot treated. The area was then wiped and rehydrated. The entire surface was then treated with a second pass. A third pass, if deemed necessary, was then used to treat the shoulders. Patients in the combined group underwent cryotherapy of the entire perioral region followed by CO2 laser treatment similar to that previously described. MAIN OUTCOME MEASURE: Improvement in facial rhytids with laser treatment alone was compared with improvement using cryotherapy and laser. A skin wrinkle grading system was used and patients were graded by 3 independent observers. Close-up photographs were obtained preoperatively and postoperatively. A questionnaire was filled out by each patient 1 month following treatment and was used to rate overall patient satisfaction. RESULTS: There was no statistically significant difference between the 2 groups regarding final outcome, amount of anesthetic agents required for each patient, or rate of complications. CONCLUSION: Superpulsed CO2 skin resurfacing alone is as effective as combined cryotherapy and superpulsed CO2 laser for treatment of perioral rhytids.

Closed dressings after laser skin resurfacing.

OBJECTIVE: To evaluate the safety, efficacy, and patient acceptance of closed dressings after full facial resurfacing with the carbon dioxide laser. DESIGN: Prospective cohort of men and women undergoing full facial carbon dioxide laser resurfacing. SETTING: Ambulatory surgical center at a university hospital. PATIENTS: Forty consecutive patients randomized to 1 of 4 dressing groups. INTERVENTIONS: All patients underwent full facial resurfacing with a carbon dioxide laser system. One of 5 closed dressings (single- or 3-layer composite foam, plastic mesh, hydrogel, or polymer film) was placed immediately after the procedure. Closed dressings were changed on postoperative day 2 and removed on postoperative day 4. OUTCOME MEASURES: Objective postoperative criteria of erythema, scarring, reepithelialization, and surface irregularities were recorded and photodocumented. Comparisons were made among the closed dressing groups as well as with a group of historical control subjects treated with open dressings. The ease of application, office time for preparation and application, and cost of the individual dressings were collected. Patient characteristics of overall acceptance, comfort, and ease of maintenance were recorded with a visual analog scale. RESULTS: There were no complications of scarring, surface irregularities, or contact dermatitis from the application or maintenance of the closed dressings. There were no significant differences in the number of days of postoperative erythema or in the rate of facial reepithelialization among the groups. Most patients preferred not to continue with the closed dressings past 2 days. Positive features from the use of closed dressings included reduction in crust formation, decreased pruritus, decreased erythema, and decreased postoperative pain, compared with historical controls. Negative features included time in preparation and application of the dressings. Costs ranged from $9.79 to $50 per dressing change. CONCLUSIONS: Closed dressings are safe and offer benefits noted during the first 4 postoperative days. Patients can be expected to maintain a closed dressing for at least 24 hours but no longer than 4 days. The positive features of closed dressings and patient acceptance outweigh the cost and office time involved with their application and maintenance.

Transcalvarial suture fixation for endoscopic brow and forehead lifts.

OBJECTIVE: To evaluate the safety and effectiveness of transcalvarial suture fixation during endoscopic repair of brow ptosis. DESIGN: Case series. SETTINGS: A private ambulatory surgicenter and a Veterans Affairs Hospital. PARTICIPANTS: Fifty patients with brow ptosis with minimum follow-up of 12 months. RESULTS: Patients had improvement in brow position in all cases. There were no adverse effects of performing cortical tunnels and suture fixation. CONCLUSION: Transcalvarial suture fixation can be performed safely with good to excellent results and avoids the need for screw or plate fixation.

Distortion of the auriculocephalic angle following rhytidectomy. Recognition and prevention.

Distortion of ear protrusion after rhytidectomy results in an aesthetically unfavorable appearance. We have seen cases in which the auriculocephalic angle has widened postoperatively, producing a noticeable deformity. Herein, we report 3 cases that resulted in abnormal postsurgical ear protrusion. We also discuss prevention through the use of conchal setback sutures.

Growth of keloid-producing fibroblasts in commercially available serum-free media.

The purpose of this study was to update our in vitro serum-free keloid fibroblast (KF) model by use of commercially available media. Prior evaluations of fibroblast characteristics in vitro, especially that of growth factor measurement, have been confounded by the presence of serum-containing media. KFs were obtained from patients undergoing facial keloid removal. The 4 commercially available serum-free media evaluated were AIM-V (Gibco, Grand Island, NY), Fibroblast Growth Medium (FGM; Clonetics, San Diego, CA), HB GRO (Irvine Scientific, Santa Ana, CA), and UltraCULTURE (BioWhittaker Inc, Walkersville, MD). The main outcome measures were sustained KF growth and viability as compared with serum-based models. The KFs in UltraCULTURE had a higher viability but did not grow as well as in FGM. The KFs in HB GRO and AIM-V demonstrated significantly decreased viability. Because of FGM's satisfactory proliferative support and viability comparable with serum-based medium, it is recommended for the in vitro propagation of keloid-producing fibroblasts.

Controversies in the management of inferior turbinate hypertrophy: a comprehensive review.

Nasal obstruction must frequently be addressed during functional rhinoplasty. Even after a properly performed septorhinoplasty correcting septal deflection and/or nasal valve collapse, nasal obstruction may persist due to turbinate hypertrophy. Turbinates have many important functions, including warming and humidification of inspired air, and numerous factors can contribute to pathologic enlargement. Management of inferior turbinate hypertrophy has been actively debated for more than a century. The primary goal of therapy is to maximize the nasal airway for as extended a period as possible while minimizing complications of therapy, such as nasal drying and hemorrhage. This review describes the various medical and surgical therapeutic modalities widely used today, with emphasis placed on surgical management of the inferior turbinates. Advantages, disadvantages, complications, and controversies of each form of treatment are reviewed and discussed. A staged protocol of increasingly invasive interventions is proposed.

The effect of superpulsed carbon dioxide laser energy on keloid and normal dermal fibroblast secretion of growth factors: a serum-free study.

An in vitro model was used to determine the effect of superpulsed CO2 laser energy on normal dermal and keloid-producing fibroblast proliferation and release of growth factors. Growth factors assayed included basic fibroblast growth factor (bFGF) and transforming growth factor beta1 (TGF-beta1). bFGF is mitogenic, inhibits collagen production, and stabilizes cellular phenotype. TGF-beta1 stimulates growth and collagen secretion and is thought to be integral to keloid formation. Growth in a serum-free medium allowed measurement of these growth factors without confounding variables. Keloid and normal dermal fibroblasts cell lines were established from facial skin samples using standard explant techniques. Samples consisted of three separate keloid and three separate normal dermal fibroblast cell lines. Cells were used at passage 4 to seed 24-well trays at a concentration of 6 x 10(4) cells per milliliter in serum-free medium. At 48 hours, 18.8 percent of each cell well was exposed to a fluence of 2.4, 4.7, and 7.3 J/cm2 using the superpulsed CO2 laser. Cell viability and counts were established at four time points: 0 (time of superpulsed CO2 laser treatment), 24, 72, and 120 hours. Supernatants were collected and assessed for bFGF and TGF-beta1 using a sandwich enzyme immunoassay. All cell lines demonstrated logarithmic growth through 120 hours (conclusion of experiment), with a statistically significant shorter population doubling time for keloid fibroblasts (p < 0.05). Use of the superpulsed CO2 laser shortened population doubling times relative to that of controls; the differences were statistically significant in keloid dermal fibroblasts when fluences of 2.4 and 4.7 J/cm2 were used (p < 0.05 and 0.01, respectively). bFGF was present in greater levels in normal dermal fibroblasts than in keloid dermal fibroblasts. Application of superpulsed CO2 demonstrated a trend toward increased bFGF secretion in both fibroblast types; the increase was significant in the keloid group at 4.7J/cm2. A consistent trend in suppression of TGF-beta1 was seen in both groups exposed to superpulsed CO2, with the maximal effect occurring at 4.7 J/cm2. Serum-free culture sustains logarithmic cell growth and allows growth factor measurement without confounding variables from serum-containing media. Superpulsed CO2 enhances fibroblast replication and seems to stimulate bFGF secretion and to inhibit TGF-beta1 secretion. Given the function of these growth factors, the application of superpulsed CO2 may support normalized wound healing. These findings may explain the beneficial effects of laser resurfacing on a cellular level and support the use of superpulsed CO2 in the management of keloid scar tissue.