Impact of housing temperature on adipose tissue HDAC9 expression and adipogenic differentiation in high fat-fed mice

OBJECTIVE

Impaired adipogenic differentiation exacerbates metabolic disease in obesity. This study reported that high-fat diet (HFD)-fed mice housed at thermoneutrality exhibited impaired adipogenic differentiation, attributed to increased expression of histone deacetylase 9 (HDAC9). However, the impact of HFD on adipogenic differentiation is reportedly variable, possibly reflecting divergent environmental conditions such as housing temperature.

METHODS

C57BL/6J (wild-type [WT]) mice were housed at either thermoneutral (28-30°C) or ambient (20-22°C) temperature and fed HFD or chow diet (CD) for 12 weeks. For acute exposure experiments, WT or transient receptor potential cation channel subfamily M member 8 (TRPM8) knockout mice housed under thermoneutrality were acutely exposed to ambient temperature for 6 to 24 h.

RESULTS

WT mice fed HFD and housed at thermoneutrality, compared with ambient temperature, gained more weight despite reduced food intake. They likewise exhibited increased inguinal adipose tissue HDAC9 expression and reduced adipogenic differentiation in vitro and in vivo compared with CD-fed mice. Conversely, HFD-fed mice housed at ambient temperature exhibited minimal change in adipose HDAC9 expression or adipogenic differentiation. Acute exposure of WT mice to ambient temperature reduced adipose HDAC9 expression independent of sympathetic β-adrenergic signaling via a TRPM8-dependent mechanism.

CONCLUSIONS

Adipose HDAC9 expression is temperature sensitive, regulating adipogenic differentiation in HFD-fed mice housed under thermoneutrality.

Integrative multiomics analysis of neointima proliferation in human saphenous vein: implications for bypass graft disease

Introduction

Human saphenous veins (SV) are widely used as grafts in coronary artery bypass (CABG) surgery but often fail due to neointima proliferation (NP). NP involves complex interplay between vascular smooth muscle cells (VSMC) and fibroblasts. Little is known, however, regarding the transcriptomic and proteomic dynamics of NP. Here, we performed multi-omics analysis in an ex vivo tissue culture model of NP in human SV procured for CABG surgery.

Methods and results

Histological examination demonstrated significant elastin degradation and NP (indicated by increased neointima area and neointima/media ratio) in SV subjected to tissue culture. Analysis of data from 73 patients suggest that the process of SV adaptation and NP may differ according to sex and body mass index. RNA sequencing confirmed upregulation of pro-inflammatory and proliferation-related genes during NP and identified novel processes, including increased cellular stress and DNA damage responses, which may reflect tissue trauma associated with SV harvesting. Proteomic analysis identified upregulated extracellular matrix-related and coagulation/thrombosis proteins and downregulated metabolic proteins. Spatial transcriptomics detected transdifferentiating VSMC in the intima on the day of harvesting and highlighted dynamic alterations in fibroblast and VSMC phenotype and behavior during NP. Specifically, we identified new cell subpopulations contributing to NP, including SPP1 + , LGALS3 + VSMC and MMP2 + , MMP14 + fibroblasts.

Conclusion

Dynamic alterations of gene and protein expression occur during NP in human SV. Identification of the human-specific molecular and cellular mechanisms may provide novel insight into SV bypass graft disease.

Mediastinal esophageal leiomyosarcoma abutting a retroesophageal right subclavian artery: A case report

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Esophageal leiomyosarcoma represent a rare esophageal malignancy.

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Arteria lusoria is defined by the anomalous development of an aberrant right subclavian artery posterior to the esophagus.

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Comprehensive and detailed preoperative planning were essential to a successful esophagus-preserving resection.

Introduction

Esophageal leiomyosarcoma and arteria lusoria represent rare entities in thoracic disease. In the setting of arteria lusoria, careful surgical planning and preoperative imaging is essential.

Presentation of case

A 53-year old male presented with a history of cough. Imaging demonstrated a 7-cm mediastinal mass at the level of the trachea and upper esophagus, abutting an incidentally found retroesophageal right subclavian artery. The right carotid artery originated from the aortic arch.

Comprehensive evaluation demonstrated a mediastinal sarcoma. Given the tumor size and close association with vital structures, induction chemotherapy was given without response. He was therefore taken for resection, including possible esophagectomy. The mass was well-encapsulated, permitting mobilization off the surrounding structures, and was identified arising from the muscular layer of the esophagus. Postoperatively, he had a low-volume chyle leak, which resolved with conservative management. He was offered mediastinal adjuvant radiation due to close margins, but declined. The patient remained without evidence of disease for over two years, at which time a single pulmonary metastasis was noted and resected.

Discussion

Esophageal leiomyosarcoma are an uncommon intrathoracic malignancy and may present with symptoms of mass effect. While patients with arteria lusoria are typically asymptomatic, they may suffer surgical morbidity if this entity is not identified preoperatively. In this case, the aberrant artery was intimately involved with the leiomyosarcoma, increasing complexity and rendering complete oncologic resection challenging.

Conclusion

Herein we present a challenging surgical resection of esophageal leiomyosarcoma in the setting of arteria lusoria, which was successfully treated tumor enucleation.

Delayed Presentation of Cardiac Perforation After Modified Ravitch Pectus Excavatum Repair

Pectus excavatum repair using a Nuss bar is a widely performed procedure and generally regarded to be quite safe. Rare catastrophic cardiovascular complications have been previously reported, by even the most experienced surgeons. These cases typically present with fulminant cardiogenic shock and have an associated high mortality rate. We present a delayed and atypical presentation for a patient with a cardiac perforation after repair of pectus excavatum who underwent successful repair.

Management of Symptomatic Hepatic "Mega" Hemangioma

The majority of giant hepatic cavernous hemangiomas are asymptomatic and can safely be observed. However, when a lesion becomes symptomatic, affecting quality of life or cannot be distinguished from a malignancy, then operative therapy should be considered. We herein present a case of a symptomatic 12cm × 14cm × 17cm "mega" hemangioma (>10cm) of the left hepatic lobe. This lesion was initially refractory to transarterial embolization of the left hepatic artery, but was subsequently treated successfully with a left lateral extended hepatic segmentectomy (resection). We thus advocate a rational treatment algorithm for management of hepatic "mega" hemangiomas.

Perforated esophageal intervention focus (PERF) study: a multi-center examination of contemporary treatment

The treatment of esophageal perforation (EP) remains a significant clinical challenge. While a number of investigators have previously documented efficient approaches, these were mostly single-center experiences reported prior to the introduction of newer technologies: specifically endoluminal stents. This study was designed to document contemporary practice in the diagnosis and management of EP at multiple institutions around the world and includes early clinical outcomes. A five-year (2009-2013) multicenter retrospective review of management and outcomes for patients with thoracic or abdominal esophageal perforation was conducted. Demographics, etiology, diagnostic modalities, treatments, subsequent early outcomes as well as morbidity and mortality were captured and analyzed. During the study period, 199 patients from 10 centers in the United States, Canada, and Europe were identified. Mechanisms of perforation included Boerhaave syndrome (60, 30.1%), iatrogenic injury (65, 32.6%), and penetrating trauma (25, 12.6%). Perforation was isolated to the thoracic segment alone in 124 (62.3%), with 62 (31.2%) involving the thoracoabdominal esophagus. Mean perforation length was 2.5 cm. Observation was selected as initial management in 65 (32.7%), with only two failures. Direct operative intervention was initial management in 65 patients (32.6%), while 29 (14.6%) underwent esophageal stent coverage. Compared to operative intervention, esophageal stent patients were significantly more likely to be older (61.3 vs. 48.3 years old, P < 0.001) and have sustained iatrogenic mechanisms of esophageal perforation (48.3% vs.15.4%). Secondary intervention requirement for patients with perforation was 33.7% overall (66). Complications included sepsis (56, 28.1%), pneumonia (34, 17.1%) and multi-organ failure (23, 11.6%). Overall mortality was 15.1% (30). In contemporary practice, diagnostic and management approaches to esophageal perforation vary widely. Despite the introduction of endoluminal strategies, it continues to carry a high risk of mortality, morbidity, and need for secondary intervention. A concerted multi-institutional, prospectively collected database is ideal for further investigation.

Endoscopic Ultrasound Estimates for Tumor Depth at the Gastroesophageal Junction Are Inaccurate: Implications for the Liberal Use of Endoscopic Resection

BACKGROUND

Endoscopic resection is increasingly utilized for treating early stage esophageal cancer, and endoscopic ultrasound (EUS) frequently guides treatment selection. Studies report greater than 80% sensitivity and 90% specificity, but our experience suggests less accuracy at the gastroesophageal (GE) junction. The objective of this study is to determine the accuracy of EUS for depth of GE junction cancer and the potential treatment implications.

METHODS

A retrospective review of a prospective database was performed for patients from 1995 to 2014 with GE junction esophageal cancer that underwent EUS staging and resection (surgical or endoscopic) without neo-adjuvant therapy. Patient, tumor, EUS, and pathologic characteristics were examined.

RESULTS

For the 181 patients that met criteria, the median age was 66 years, 17% were female, 91% white, and 98% had adenocarcinoma. Concordance between EUS (u) T and pathologic (p) T was 48%, with 23% under-staged and 29% over-staged. The EUS was accurate in the following: uT0 6% (1 of 18); uT1a 56% (23 of 41); uT1b 58% (41 of 71); uT2 10% (2 of 21); and uT3 70% (21 of 30). Inaccurate EUS depth had potential to lead to over-treatment in 38% (27 of 71) of uT1b and 76% (16 of 21) of uT2. In 50% of pT1a tumors, EUS depth was T1b or greater. Logistic regression revealed tumor length (continuous variable) to be associated with inaccurate uT (p = 0.016). Accurately staged tumors were significantly longer than inaccurately staged tumors (2.7 vs 1.7 cm, p = 0.011).

CONCLUSIONS

Early to intermediate GE junction tumors are frequently over-staged. This highlights the importance of diagnostic endoscopic resection for determining accurate tumor depth and selecting correct therapy.

Laparoscopic sleeve gastrectomy: outcomes at a military training center

Laparoscopic sleeve gastrectomy (LSG) has gained support as a single-staged and stand-alone bariatric procedure. Reports of excess weight loss of 35 to 83 per cent, reduction in comorbidities, and decreased operative morbidity have garnered support for LSG. This study represents an initial outcome analysis of LSG performed solely at a military treatment center. This study is a retrospective analysis of all patients receiving LSG at Dwight D. Eisenhower Army Medical Center from September 2007 to December 2009. The patients were planned for a stand-alone procedure. One hundred and fifteen patients received LSG over this time period with a mean body mass index of 45.5 +/- 6.2 (range 35.1-58.3). The average age was 47.4 +/- 12.5 years. Diabetes mellitus was seen in 47 per cent and 68 per cent of patients had hypertension. The mean and median length of operation was 124 +/- 48 and 115.5 minutes. The mean percentage of excess weight loss was 16.6 +/- 6.40 per cent at 1 month, 31.5 +/- 7.6 per cent at 3 months, 41.2 +/- 13.9 per cent at 6 months, and 53.7 +/- 12.5 per cent at 1 year from surgery. One or more of patient's preoperative diabetic or hypertensive medications were improved postoperatively in 18.7 per cent and 16.3 per cent, respectively. Incidence of major complications occurred in 4.35 per cent of patients in this study to include four leaks (3.4%), one death (0.87%), and 10 readmissions. Midterm analysis of outcomes related to LSG as a single-stage bariatric procedure is promising as long-term outcome data is collected; the efficacy of this procedure as a sole bariatric procedure will continue to be borne out.

Laparoscopic Sleeve Gastrectomy: Outcomes at a Military Training Center

Laparoscopic sleeve gastrectomy (LSG) has gained support as a single-staged and stand-alone bariatric procedure. Reports of excess weight loss of 35 to 83 per cent, reduction in comorbidities, and decreased operative morbidity have garnered support for LSG. This study represents an initial outcome analysis of LSG performed solely at a military treatment center. This study is a retrospective analysis of all patients receiving LSG at Dwight D. Eisenhower Army Medical Center from September 2007 to December 2009. The patients were planned for a stand-alone procedure. One hundred and fifteen patients received LSG over this time period with a mean body mass index of 45.5 ± 6.2 (range 35.1-58.3). The average age was 47.4 ± 12.5 years. Diabetes mellitus was seen in 47 per cent and 68 per cent of patients had hypertension. The mean and median length of operation was 124 ± 48 and 115.5 minutes. The mean percentage of excess weight loss was 16.6 ± 6.40 per cent at 1 month, 31.5 ± 7.6 per cent at 3 months, 41.2 ± 13.9 per cent at 6 months, and 53.7 ± 12.5 per cent at 1 year from surgery. One or more of patient's preoperative diabetic or hypertensive medications were improved postoperatively in 18.7 per cent and 16.3 per cent, respectively. Incidence of major complications occurred in 4.35 per cent of patients in this study to include four leaks (3.4%), one death (0.87%), and 10 readmissions. Midterm analysis of outcomes related to LSG as a single-stage bariatric procedure is promising as long-term outcome data is collected; the efficacy of this procedure as a sole bariatric procedure will continue to be borne out.

Comparison of Surgisis, AlloDerm, and Vicryl Woven Mesh grafts for abdominal wall defect repair in an animal model

BACKGROUND

Surgisis and AlloDerm, two biosynthetic materials, have been previously used with success in abdominal wall repairs in the setting of contaminated fields. Historically, Vicryl Woven Mesh, a synthetic material, has also been used in such settings as a temporary bridge for abdominal wall reconstruction. This study compares Surgisis and AlloDerm with Vicryl Woven Mesh with respect to tensile strength, collagen remodeling, and neovascularization using a rat hernia model.

METHODS

A prospective randomized trial of 54 Sprague-Dawley rats were assigned to the Surgisis, AlloDerm, or Vicryl Woven Mesh group with baseline, 30-day, and 60-day end points. A 1.5-cm x 5.0-cm defect was created in the right abdominis rectus muscle and repaired with an underlay bridge graft using the different treatment materials. Tensile strength was measured using an Instron tensiometer. Histologic specimens were evaluated for neovascularization, collagen deposition, and collagen organization at the 30- and 60-day time points.

RESULTS

Surgisis had significantly greater tensile strength compared to Vicryl Woven Mesh at the baseline time point (0.142 vs. 0.091 MPa, p < 0.05). There were no differences between groups tensile strength at 30 or 60 days postoperatively. The Vicryl Woven Mesh and AlloDerm groups showed increases in tensile strength at 30 days postoperatively versus baseline (p < 0.05). Vicryl Woven Mesh, Surgisis, and AlloDerm all showed increases in tensile strength at 60 days postoperatively compared to 30 days postoperatively and at baseline (p < 0.05). Surgisis and AlloDerm had significantly greater (p < 0.05) amounts of collagen deposition and organization at 30 and 60 days compared to Vicryl Woven Mesh. There was no significant difference between AlloDerm and Surgisis with respect to collagen deposition and organization. Surgisis and AlloDerm showed a significantly greater amount (p < 0.05) of neovascularization than Vicryl Woven Mesh at both time points. In addition, Surgisis had a significantly greater amount (p < 0.05) of neovascularization than AlloDerm at both 30 and 60 days.

CONCLUSION

Surgisis has increased baseline tensile strength compared to Vicryl Woven Mesh. Tensile strength in Vicryl Woven Mesh is equal to biosynthetic grafts after tissue incorporation. Biosynthetic grafts showed superior collagen deposition and organization. Surgisis mesh showed increased neovascularization over both AlloDerm and Vicryl Woven Mesh.

Pre-engraftment syndrome after double-unit cord blood transplantation: a distinct syndrome not associated with acute graft-versus-host disease

Pre-engraftment syndrome (PES) occurring after cord blood transplantation (CBT) is poorly characterized. We reviewed 52 consecutive double-unit CBT recipients treated for high-risk hematologic malignancies. PES was defined as unexplained fever >38.3 degrees C (101 degrees F) not associated with infection and unresponsive to antimicrobials, and/or unexplained rash occurring before or at neutrophil recovery. CBT recipients (median age, 38 years; range, 3-66 years) received either myeloablative (MA; n=36) or nonmyeloablative (NMA; n=16) conditioning. Sixteen patients (31%) fulfilled PES criteria: 15 with fever (median at onset, 39 degrees C [102.2 degrees F]), 13 of whom also had rash, and 1 with rash alone. The median onset was 9 days (range, 5-12 days) posttransplantation (a median of 14 days before neutrophil recovery). Sixteen patients (14 with PES and 2 with infection and possible PES) received intravenous methylprednisolone (median dose, 1mg/kg; median duration, 3 days); 15 (94%) experienced resolution of fever within 24 hours. Recurrent PES (n=3) resolved with retreatment. There was no association between the development of PES and the likelihood of sustained donor engraftment, speed of neutrophil recovery, grade II-IV acute graft-versus-host disease (aGVHD), day-180 treatment-related mortality (TRM), or survival. PES is common after CBT, precedes neutrophil recovery, is distinct from and does not predict for aGVHD, and responds promptly to short-course corticosteroid therapy.

A "no-wash" albumin-dextran dilution strategy for cord blood unit thaw: high rate of engraftment and a low incidence of serious infusion reactions

Preparation of cord blood (CB) units for infusion by albumin-dextran dilution without centrifugation may be advantageous for adult patients to minimize cell loss and, unlike a bedside thaw, is still conducted in the controlled laboratory environment. Therefore, we studied CB transplantation (CBT) using this technique in 54 consecutive CBT recipients >20 kg. Patients (median age=42 years [range: 7-66 years]; median weight=71 kg [range: 24-109]) were transplanted for high-risk hematologic malignancies with myeloablative (n=35) or nonmyeloablative (n=19) conditioning and 4-6/6 human leukocyte antigen (HLA)-matched double-unit grafts. One hundred seven units were thawed with dilution, whereas 1 red blood cell (RBC)-replete unit was washed. A 5:1 dextran 40%/25% albumin solution was used. RBC-depleted units (n=104) were diluted >or=5.5-fold (median final volume 200 mL [range: 200-500]), whereas RBC-replete units (n=3) were diluted >or=4-fold (median final volume 400 mL [range: 400-535]). Total nucleated cell (TNC) recovery was 86%; the median infused TNC dose was 2.17x10(7)/kg/unit. Although 35 patients (65%) had a total of 45 infusion reactions (6 nausea, 31 hypertension, 3 pain, 1 rigors/fever, 2 transient hypoxia, 2 renal impairment) requiring additional therapy, there were no infusion-related serious adverse events, and reactions were not related to dimethyl sulfoxide (DMSO) dose/kg. Cumulative incidence of sustained donor engraftment was 94% (95% cumulative incidence [CI]: 87-100) with neutrophil recovery occurring at a median of 25 days (range: 13-43) in myeloablative and 10 days (range: 7-36) in nonmyeloablative recipients. CB thaw with albumin-dextran dilution reduces unit manipulation, and minimizes cell loss, speeds time to infusion, is associated with a tolerable infusion reaction profile, and a high rate of sustained engraftment in CBT recipients >or=20 kg.

The role of FDG-PET imaging and involved field radiotherapy in relapsed or refractory diffuse large B-cell lymphoma

We examined the role of fluorodeoxyglucose-positron emission tomography (FDG-PET) and the addition of involved field radiotherapy (IFRT) as potential modifiers of salvage therapy. From January 2000 to June 2007, 83 patients with chemosensitive relapsed or primary refractory diffuse large B-cell lymphoma (DLBCL) underwent FDG-PET scans following second-line chemotherapy before high-dose therapy with autologous stem cell rescue (HDT/ASCR). We evaluated the prognostic value of having a negative FDG-PET scan before HDT/ASCR and whether IFRT improved the outcomes. Median follow-up was 45 months, and the 3-year PFS, disease-specific survival (DSS) and OS were 72, 80 and 78%, respectively. Multivariate analysis revealed that a positive FDG-PET scan had worse PFS (hazard ratio=(HR) 3.4; P=0.014), DSS (HR=7.7; P=0.001) and OS (HR=5.4; P=0.001), and that patients not receiving IFRT had worse PFS (HR=2.7; P=0.03) and DSS (HR=2.8, P=0.059). Patients who received IFRT had better local control with fewer relapses within prior involved sites compared with those that did not receive IFRT (P=0.006). These outcomes confirm the important prognostic value of FDG-PET scans before undergoing HDT/ASCR. It also suggests that the role of IFRT should be evaluated further.

Evaluation of pharyngeal and laryngeal structure and function in patients with oculo-auriculo-vertebral spectrum

OBJECTIVE

This study described the occurrence and expression of pharyngeal and laryngeal anomalies in a population of patients with oculo-auriculo-vertebral spectrum (OAVS).

DESIGN

Cross-sectional study using chart review, physical examination, and endoscopic evaluation of the pharynx and larynx, and perceptual and aerodynamic evaluation of speech for assessment of vocal tract function.

SETTING

Academic tertiary referral center.

PATIENTS

Chart review of 41 patients with a diagnosis of OAVS and clinical evaluation of 23 of the patients identified in the initial chart review, ranging in age from 9 months to 17 years.

MAIN OUTCOME MEASURES

Data from chart review pertaining to airway and speech symptoms. Physical examination and endoscopic studies of pharyngeal and laryngeal structure and function and perceptual and aerodynamic evaluation of speech, resonance, and voice.

RESULTS

Chart review showed a high occurrence of indicators of pharyngeal and laryngeal abnormalities such as velopharyngeal inadequacy and airway obstruction. Clinical evaluations documented a variety of abnormalities in pharyngeal and laryngeal structure and function as well as impairment in speech articulation, resonance, and voice. Presence and severity of pharyngeal and laryngeal abnormalities were not correlated with the severity of expression of the spectrum based on mandibular morphology.

CONCLUSIONS

Oculo-auriculo-vertebral spectrum appears to be associated with a high occurrence of structural and functional abnormalities of the pharynx and larynx that may contribute to increased risk of airway obstruction, communication impairment, and morbidity.

Use of the tunable dye laser to delay McFarlane skin flaps

OBJECTIVE

To determine whether the argon tunable dye laser, used in a noncutting, hemocoagulative mode, improves skin flap survival as effectively as a surgical delay procedure.

DESIGN

A physiologic, controlled trial was completed with three groups: acute control skin flaps, surgical delay skin flaps, and experimental laser delay skin flaps. The outcome variable was percentage of skin flap survival.

SUBJECTS

Forty-four male Sprague-Dawley rats.

INTERVENTIONS

McFarlane skin flaps were raised in all groups. The first group had no delay procedure, the second had the standard surgical delay, and the third group was lased at the periphery of the flap 2 weeks before raising the acute flap.

RESULTS

The acute control group had survival of 85.7% +/- 1.5% (mean +/- SE) of skin flaps; surgical control group, 94.4% +/- 0.7%; laser delay group, 96.5% +/- 0.1%. The survival of the experimental group was better than the acute control group and was not different from the surgical delay group by the Scheffé multiple comparison test.

CONCLUSIONS

This research may lead to a technique to reproduce the benefits of the delay phenomenon without the risks and cost of a surgical procedure.

Comparison of tunable dye and KTP lasers in nonsurgical delay of cutaneous flaps

PROBLEM

Reproducing the benefits of the delay phenomenon without the risks and costs of a surgical procedure has long been a goal of skin flap physiologists. After the success of the suture-delay technique and argon tunable dye laser in improving survival in McFarlane skin flaps, important questions remained: (1) will laser delay be effective in dermal flaps, (2) can induction of collateral blood flow be documented, and (3) is the KTP laser, which is generally more available to otolaryngologists, more effective than the argon tunable dye laser.

METHODS

The KTP and argon tunable dye lasers were compared by use of the laser-delay technique, with two outcome measures - blood flow and survival. The laser-delay procedure was accomplished with the laser in a noncutting mode in an attempt to coagulate cutaneous vessels at the periphery of a planned skin flap. The objective was to induce collateralization and improve skin flap survival. Patterns of blood flow were tested by use of the base occlusion test. Flap survival of an acute control flap group was compared with that of the laser delay groups.

RESULTS

Blood flowing to the distal flap area originated from the base of the flap area after laser delay. Flap survival of the laser delay groups was significantly improved over that of the control group.

CONCLUSION

Both lasers were able to effectively induce collateralization and improve flap survival.

Comparison of Tunable Dye and KTP Lasers in Nonsurgical Delay of Cutaneous Flaps

PROBLEM: Reproducing the benefits of the delay phenomenon without the risks and cost of a surgical procedure has long been a goal of skin flap physiologists. After the success of the suture-delay technique and argon tunable dye laser in improving survival in McFarlane skin flaps, important questions remained: (1) will laser delay be effective in dermal flaps, (2) can induction of collateral blood flow be documented, and (3) is the KTP laser, which is generally more available to otolaryngologists, more effective than the argon tunable dye laser.

METHODS: The KTP and argon tunable dye lasers were compared by use of the laser-delay technique, with two outcome measures-blood flow and survival. The laser-delay procedure was accomplished with the laser in a noncutting mode in an attempt to coagulate cutaneous vessels at the periphery of a planned skin flap. The objective was to induce collateralization and improve skin flap survival. Patterns of blood flow were tested by use of the base occlusion test. Flap survival of an acute control flap group was compared with that of the laser delay groups.

RESULTS: Blood flowing to the distal flap area originated from the base of the flap area after laser delay. Flap survival of the laser delay groups was significantly improved over that of the control group.

CONCLUSION: Both lasers were able to effectively induce collateralization and improve flap survival.

Merkel cell tumor of the head and neck. Five new cases with literature review

Merkel cell carcinoma (MCC) of the skin is an uncommon, but highly aggressive neoplasm with a marked propensity for local and distant metastasis. Despite the fact that more than half of the 600 cases of MCC reported in the literature involved primary sites in the head and neck, MCC has rarely been discussed in otolaryngology publications. We present five new cases of MCC of the head and neck and summarize 89 additional cases from the literature in which detailed treatment and survival data were given. Our findings again emphasize the difficulty in making the initial histopathologic diagnosis of MCC and demonstrate the necessity of early diagnosis and multimodality treatment.