Lytic to temperate switching of viral communities.

Microbial viruses can control host abundances via density-dependent lytic predator-prey dynamics. Less clear is how temperate viruses, which coexist and replicate with their host, influence microbial communities. Here we show that virus-like particles are relatively less abundant at high host densities. This suggests suppressed lysis where established models predict lytic dynamics are favoured. Meta-analysis of published viral and microbial densities showed that this trend was widespread in diverse ecosystems ranging from soil to freshwater to human lungs. Experimental manipulations showed viral densities more consistent with temperate than lytic life cycles at increasing microbial abundance. An analysis of 24 coral reef viromes showed a relative increase in the abundance of hallmark genes encoded by temperate viruses with increased microbial abundance. Based on these four lines of evidence, we propose the Piggyback-the-Winner model wherein temperate dynamics become increasingly important in ecosystems with high microbial densities; thus 'more microbes, fewer viruses'.

Low-energy helium-neon laser irradiation increases the motility of cultured human keratinocytes.

Helium-neon (HeNe) laser irradiation is known to stimulate wound healing. We investigated whether the biostimulatory effects of HeNe irradiation result from enhancement of keratinocyte proliferation or motility. HeNe effects on keratinocyte motility were evaluated by irradiating a "wounded" culture with 0.8 J/cm2 3 times over a 20-h period. At 20 h post-irradiation, videocinemicroscopy and sequential quantitative measurements of the leading edge were taken over a 6-h period. There was a significant difference in migration of the leading edge in irradiated "wounds" compared to non-irradiated "wounded" controls (12.0 microns/h vs 4.0 microns/h, p less than 0.0001). To determine if the increase in migration observed in irradiated cultures resulted from a proliferative effect of HeNe irradiation, subconfluent human keratinocyte cultures were irradiated with single or multiple doses of different fluences of HeNe irradiation (0.4 to 7.2 J/cm2) and evaluated 72 h post-irradiation. Irradiated and non-irradiated keratinocyte cultures grown on a microporous membrane surface were co-cultured with irradiated and non-irradiated fibroblasts to determine if HeNe irradiation induced a paracrine effect on keratinocyte proliferation. No significant increase in keratinocyte proliferation was demonstrated in any of these treatments. The biostimulatory effects of HeNe irradiation may now be extended to include enhancement of keratinocyte motility in vitro; this may contribute to the efficacy of HeNe irradiation in wound healing.

Low-energy helium neon laser irradiation does not alter human keratinocyte differentiation.

There are reports that low-energy HeNe irradiation can enhance wound healing in vivo. We have previously demonstrated that HeNe irradiation increases the motility of human epidermally derived keratinocytes in vitro. Here we investigate whether HeNe irradiation alters normal keratinocyte differentiation, which is essential for the formation of a normal, functioning epidermis. Subconfluent keratinocyte cultures were irradiated three times within 24 h with either 0, 0.8, 3, or 7.2 J/cm2. After cultures reached post-confluence, parameters of growth and differentiation, such as cell number, cornified envelope (CE) formation, and transglutaminase activity were measured. No significant differences were found between the control (0 J) and irradiated cultures in these assays. We also examined the pattern of newly synthesized keratins in cultures irradiated with 7.2 J/cm2 three times within a 24-h period. Both control and irradiated cultures exhibited similar keratin patterns. These results provide evidence that HeNe irradiations of up to 7.2 J/cm2 have no direct deleterious effect on normal keratinocyte differentiation needed for the formation of a functional epidermis. Hence, it is anticipated that the clinical use of the HeNe laser irradiance that enhances keratinocyte migration in vitro (0.8 J/cm2) to promote wound healing in vivo will not alter the ultimate integrity or differentiated function of the epidermis that migrates to cover the wounded area.

Redox regulation of wound healing? NF-kappaB activation in cultured human keratinocytes upon wounding and the effect of low energy HeNe irradiation.

The complex process of wound healing as well as the signaling systems orchestrating this intricate process remain incompletely defined. Using human keratinocytes in primary culture, we sought to characterize their NF-kappaB responses to wounding alone or in combination with other treatments. We initially characterized these cultured human keratinocytes responses to known NF-kappaB activators (PMA, TNF-alpha and IL-1) using two different assays, immunohistochemistry and electrophoretic mobility shift (EMSA). After eliciting the expected NF-kappaB responses, we applied these same assays to assess responses to either wounding or HeNe irradiation alone. The results obtained indicated that only a modest/sporadic activation of NF-kappaB was elicited by these which was only detectable using immunohistochemistry. When the combination of wounding and HeNe irradiation on NF-kappaB status was assessed, a marked, localized activation of NF-kappaB in keratinocytes along the wound edge was found. Treatment induced NF-kappaB activation (e.g., wounding, HeNe irradiation and combined wounding and HeNe irradiation) was abrogated by pyrrolidine dithiocarbamate (PDTC) which inhibits NF-kappaB activation through an as yet incompletely understood (antioxidant?) mechanism. These data therefore suggest that NF-kappaB and oxidation mediated changes in its activation state likely play important roles in normal cutaneous wound healing.

Multispecialty approach to complex dermatofibrosarcoma protuberans of the forehead.

We describe a 38-year-old woman with extensive dermatofibrosarcoma protuberans of the forehead and discuss the advantages of using a multispecialty approach in the treatment of this case. The patient had had an incomplete resection 15 years previously, with a misdiagnosis of the actual tumor type. After undergoing a biopsy and a computed tomographic scan, the patient underwent Mohs micrographic surgery, followed by split-thickness grafting. Ultimate reconstruction was performed 15 months later using bilateral temporoparietal fascial flaps, in addition to split-thickness grafting. The patient remains tumor-free 3 years after resection.

Operative ankle arthroscopy. Long-term followup.

Ankle arthroscopy has become an accepted procedure for the treatment of various intraarticular disorders. More than 100 ankle arthroscopies have been performed at our institution since 1983. To better define the role of arthroscopic surgery in the treatment of ankle disorders, we evaluated the preoperative examination and indications, operative data, and radiographs of those patients with a minimum of 1 year of followup. Fifty-eight ankles in 57 patients were identified; their average follow-up period was 25 months (range, 12 to 49 months). Preoperative diagnoses were synovitis (26), transchondral defects of the talus (17), degenerative joint disease (8), and osteophytes or loose bodies (7). Subjective results were good or excellent in 64% of cases. The best overall results were achieved in patients with synovitis (77%) and transchondral defects of the talus (71%). Degenerative joint disease patients did not do well. They had only 12% good or excellent results and a 43% rate of subsequent fusion. Complications included superficial and deep infections, temporary and permanent paresthesias, and hemarthroses; the overall complication rate was 15%. In conclusion, operative ankle arthroscopy can be useful in selected patients. It is an effective surgical procedure in patients with synovitis and transchondral defects of the talus. The benefits and long-term results are less predictable with loose bodies and impinging osteophytes; the results are poor with degenerative joint disease. There appears to be a significant risk of complication with ankle arthroscopy; however, with proper indications, a thorough knowledge of anatomical landmarks, and meticulous technique, good results can be obtained.

Wound healing.

The biology of wound healing is not only important to scientists, but also to those involved clinically in caring for wounds. Knowledge gained about wound healing from the laboratory influences not only how certain wounds are created and treated, but also influences development of new products and methods designed to facilitate wound healing.

Nodular fasciitis of the forehead.

BACKGROUND: Nodular fasciitis is a benign, fibrohistiocytic tumor most commonly arising on the trunk. Histopathologically it can be misdiagnosed as a sarcoma. OBJECTIVE: To describe a case of nodular fasciitis on the forehead and to review the clinical and histologic characteristics of the tumor. METHODS: Case report and review of the literature. RESULTS: Local excision to completely remove tumor has proven curative at 1 year of follow-up. CONCLUSION: Nodular fasciitis can be encountered on the head and neck and should be regarded as a benign tumor. Either minimal excision or even a "watch and wait" plan can be successful in treating this tumor.

Antibiotic prophylaxis.

The appropriate use of antibiotic prophylaxis is confusing for all surgeons and it is certainly not straight-forward for dermatologists. There are no set guidelines which encompass skin surgery. This article reviews antibiotic prophylaxis both to prevent wound infections and to prevent endocarditis. Some of the issues and controversies surrounding the use of antibiotic prophylaxis are discussed, and guidelines are provided which should be of assistance to those who perform dermatologic surgery.

Recalcitrant breast lymphangioma circumscriptum treated by UltraPulse carbon dioxide laser.

BACKGROUND: Lymphangioma circumscriptum is a relatively rare cutaneous disorder, consisting of superficial and deep lymphatic cisterns. These vascular blebs are difficult to treat, frequently recur, and can cause patients significant morbidity. OBJECTIVE: We report a difficult case of lymphangioma circumscriptum, recurrent from a two prior surgical treatments, which was treated in a straightforward manner by one of the newer, high-energy, short-pulse carbon dioxide (CO2) lasers. METHODS: Report of a case and literature review. CONCLUSION: Like continuous-wave CO2 laser systems, the newer, high-energy, short-pulse CO2 laser may be effective in vaporizing some of the surface lymphatic vessels, which may in turn seal some of the communicating channels to the deeper cisterns, yielding functionally and cosmetically acceptable results for this difficult disorder. However, given the nature of the lesion, the potential for recurrence exists no matter what modality is chosen.

Antibiotic prophylaxis in dermatologic surgery.

Antibiotic prophylaxis is generally administered either to prevent wound infection or to hinder the development of endocarditis. Although the use of antibiotics in certain circumstances to prevent wound infection can be straightforward, there are other circumstances in which the decision to use antibiotics is much less clear. Endocarditis prophylaxis has traditionally been based on the American Heart Association's guidelines, which do not cover dermatologic surgery. This article discusses the rationale and controversies surrounding the use of antibiotic prophylaxis for prevention of both wound infection and endocarditis, reviews the few studies that pertain to dermatology, and provides recommendations for antibiotic prophylaxis on a case-by-case basis for those who perform dermatologic surgery.

Angiolymphoid hyperplasia with eosinophilia of the hand. A case report.

Angiolymphoid hyperplasia with eosinophilia is an uncommon benign vascular neoplasm manifested by multiple or solitary subcutaneous nodules, usually on or about the head of young adults. Angiolymphoid hyperplasia with eosinophilia is characterized microscopically by marked proliferation of large endothelial cells with a mixed inflammatory infiltrate consisting of lymphocytes, histiocytes, and eosinophils. This benign skin disorder may resemble an angiosarcoma both clinically and histologically. We wish to report a patient with angiolymphoid hyperplasia with eosinophilia on the palm of the hand and discuss therapeutic recommendations.

Spindle cell lipoma of the scalp: a case report and review.

Cutaneous surgeons frequently evaluate and manage soft tissue tumors arising on the head and neck of adults. Of these, the most common tumor is the lipoma, and specific mesenchymal variants of lipoma occur classically on the head and neck. We describe a case of a large spindle cell lipoma of the posterior scalp, in order to highlight the classic location and differential diagnosis of the lipoma variants presenting commonly in this anatomic region. In addition, we review the role of preoperative imaging studies of scalp soft tissue tumors and discuss how imaging may assist the dermatologic surgeon in establishing the diagnosis and designing a rational surgical approach.

Retropharyngeal hematomas.

Hyperextension of the cervical spine in the elderly can cause retropharyngeal hematomas. We report this unusual cause of retropharyngeal hematoma in a 77-year-old women. The airway must be thoroughly evaluated in any such patient in whom this lesion is suspected.