Targeted intracellular voltage recordings from dendritic spines using quantum-dot-coated nanopipettes.

Dendritic spines are the primary site of excitatory synaptic input onto neurons, and are biochemically isolated from the parent dendritic shaft by their thin neck. However, due to the lack of direct electrical recordings from spines, the influence that the neck resistance has on synaptic transmission, and the extent to which spines compartmentalize voltage, specifically excitatory postsynaptic potentials, albeit critical, remains controversial. Here, we use quantum-dot-coated nanopipette electrodes (tip diameters ∼15-30 nm) to establish the first intracellular recordings from targeted spine heads under two-photon visualization. Using simultaneous somato-spine electrical recordings, we find that back propagating action potentials fully invade spines, that excitatory postsynaptic potentials are large in the spine head (mean 26 mV) but are strongly attenuated at the soma (0.5-1 mV) and that the estimated neck resistance (mean 420 MΩ) is large enough to generate significant voltage compartmentalization. Nanopipettes can thus be used to electrically probe biological nanostructures.

Topical Minocycline Effectively Decontaminates and Reduces Inflammation in Infected Porcine Wounds.

BACKGROUND: Wound infection can impair postoperative healing. Topical antibiotics have potential to treat wound infection and inflammation and minimize the adverse effects associated with systemic antibiotics. METHODS: Full-thickness porcine wounds were infected with Staphylococcus aureus. Using polyurethane wound enclosure devices, wounds were treated with topical 100 µg/ml minocycline, topical 1000 µg/ml minocycline, topical saline control, or 4 mg/kg intravenous minocycline. Bacteria were quantified in wound tissue and fluid obtained over 9 hours. Immunosorbent assays were used to analyze inflammatory marker concentrations. Minocycline's effect on in vitro migration and proliferation of human keratinocytes and fibroblasts was tested using scratch assays and metabolic assays, respectively. RESULTS: After 6 hours, 100 and 1000 µg/ml topical minocycline decreased bacteria in wound tissue to 3.5 ± 0.87 and 2.9 ± 2.3 log colony-forming units/g respectively, compared to 8.3 ± 0.9 log colony-forming units/g in control wounds (p < 0.001) and 6.9 ± 0.2 log colony-forming units/g in wounds treated with 4 mg/kg intravenous minocycline (p < 0.01). After 2 hours, topical minocycline reduced concentrations of the inflammatory cytokines interleukin-1ß, interleukin-6, and tumor necrosis factor-α (p < 0.01), and inflammatory cell counts in wound tissue (p < 0.05). In noninfected wounds, topical minocycline significantly reduced interleukin-1ß, interleukin-6, and inflammatory cell counts after 4 hours (p < 0.01). Matrix metalloproteinase-9 concentrations decreased after 1-hour treatment (p < 0.05). Keratinocyte and fibroblast in vitro functions were not adversely affected by 10 µg/ml minocycline or less. CONCLUSIONS: Topical minocycline significantly reduces bacterial burden and inflammation in infected wounds compared with wounds treated with intravenous minocycline or control wounds. Minocycline also decreases local inflammation independently of its antimicrobial effect.

Full-thickness porcine burns infected with Staphylococcus aureus or Pseudomonas aeruginosa can be effectively treated with topical antibiotics.

Burn and blast injuries are frequently complicated by invasive infections, which lead to poor wound healing, delay in treatment, disability, or death. Traditional approach centers on early debridement, fluid resuscitation, and adjunct intravenous antibiotics. These modalities often prove inadequate in burns, where compromised local vasculature limits the tissue penetration of systemic antibiotics. Here, we demonstrate the treatment of infected burns with topical delivery of ultrahigh concentrations of antibiotics. Standardized burns were inoculated with Staphylococcus aureus or Pseudomonas aeruginosa. After debridement, burns were treated with either gentamicin (2 mg/mL) or minocycline (1 mg/mL) at concentrations greater than 1,000 times the minimum inhibitory concentration. Amount of bacteria was quantified in tissue biopsies and wound fluid following treatment. After six days of gentamicin or minocycline treatment, S. aureus counts decreased from 4.2 to 0.31 and 0.72 log CFU/g in tissue, respectively. Similarly, P. aeruginosa counts decreased from 2.5 to 0.0 and 1.5 log CFU/g in tissue, respectively. Counts of both S. aureus and P. aeruginosa remained at a baseline of 0.0 log CFU/mL in wound fluid for both treatment groups. The findings here demonstrate that super-therapeutic concentrations of antibiotics delivered topically can rapidly reduce bacterial counts in infected full-thickness porcine burns. This treatment approach may aid wound bed preparation and accelerate time to grafting.

Implications of Rheumatic Disease and Biological Response-Modifying Agents in Plastic Surgery.

The preoperative evaluation for any reconstructive or aesthetic procedure requires a detailed history of existing medical conditions and current home medications. The prevalence of rheumatic diseases such as rheumatoid arthritis, gout, and psoriasis is high, but the impact of these chronic illnesses on surgical outcome and the side effects of the powerful medications used for treatment are often underappreciated. In this review, the authors highlight key perioperative considerations specific to rheumatologic diseases and their associated pharmacologic therapies. In particular, the authors discuss the perioperative management of biological response-modifying agents, which have largely become the new standard of therapy for many rheumatic diseases. The literature reveals three key perioperative concerns with biological therapy for rheumatic disease: infection, wound healing delays, and disease flare. However, data on specific perioperative complications are lacking, and it remains controversial whether withholding biological therapy before surgery is of benefit. The risk of these adverse events is influenced by several factors: age, sex, class of biological agent, duration of exposure, dosage, onset and severity of disease, and type of surgical procedure. Overall, it remains best to develop an individualized plan. In younger patients with recent onset of biological therapy, it is reasonable to withhold therapy based on 3 to 5 half-lives of the specific agent. In older patients with a substantial history of rheumatic disease, the decision to discontinue therapy must be weighed and decided carefully in conjunction with the rheumatologist.

Topical delivery of ultrahigh concentrations of gentamicin is highly effective in reducing bacterial levels in infected porcine full-thickness wounds.

BACKGROUND: Injury to the skin can predispose individuals to invasive infection. The standard of care for infected wounds is treatment with intravenous antibiotics. However, antibiotics delivered intravenously may have poor tissue penetration and be dose limited by systemic side effects. Topical delivery of antibiotics reduces systemic complications and delivers increased drug concentrations directly to the wound. METHODS: Porcine full-thickness wounds infected with Staphylococcus aureus were treated with ultrahigh concentrations (over 1000 times the minimum inhibitory concentration) of gentamicin using an incubator-like wound healing platform. The aim of the present study was to evaluate clearance of infection and reduction in inflammation following treatment. Gentamicin cytotoxicity was evaluated by in vitro assays. RESULTS: Application of 2000 µg/ml gentamicin decreased bacterial counts in wound tissue from 7.2 ± 0.3 log colony-forming units/g to 2.6 ± 0.6 log colony-forming units/g in 6 hours, with no reduction observed in saline controls (p < 0.005). Bacterial counts in wound fluid decreased from 5.7 ± 0.9 log colony-forming units/ml to 0.0 ± 0 log colony-forming units/ml in 1 hour, with no reduction observed in saline controls (p < 0.005). Levels of interleukin-1ß were significantly reduced in gentamicin-treated wounds compared with saline controls (p < 0.005). In vitro, keratinocyte migration and proliferation were reduced at gentamicin concentrations between 100 and 1000 µg/ml. CONCLUSIONS: Topical delivery of ultrahigh concentrations of gentamicin rapidly decontaminates acutely infected wounds and maintains safe systemic levels. Treatment of infected wounds using the proposed methodology protects the wound and establishes a favorable baseline for subsequent treatment.

Current preventive measures for health-care associated surgical site infections: a review.

Healthcare-associated infections (HAIs) continue to be a tremendous issue today. It is estimated 1.7 million HAIs occur per year, and cost the healthcare system up to $45 billion annually. Surgical site infections (SSIs) alone account for 290,000 of total HAIs and approximately 8,000 deaths. In today's rapidly changing world of medicine, it is ever important to remain cognizant of this matter and its impact both globally and on the individual lives of our patients. This review aims to impress upon the reader the unremitting significance of HAIs in the daily practice of medicine. Further, we discuss the etiology of HAIs and review successful preventive measures that have been demonstrated in the literature. In particular, we highlight preoperative, intraoperative, and postoperative interventions to combat SSIs. Finally, we contend that current systems in place are often insufficient, and emphasize the benefits of institution-wide adoption of multiple preventive interventions. We hope this concise update and review can inspire additional dialogue for the continuing progress towards improving patient care and patient lives.

Transillumination of the occult submucous cleft palate.

Occult submucous cleft palate is a congenital deformity characterized by deficient union of the muscles that normally cross the velum and aid in elevation of the soft palate. Despite this insufficient muscle coverage, occult submucous cleft palate by definition lacks clear external anatomic landmarks. This absence of anatomic signs makes diagnosis of occult submucous cleft less obvious, more dependent on ancillary tests, and potentially missed entirely. Current diagnostic methodologies are limited and often are unrevealing in the presurgical patient; however, a missed diagnosis of occult submucous cleft palate can result in velopharyngeal insufficiency and major functional impairment in patients after surgery on the oropharynx. By accurately and easily diagnosing occult submucous cleft palate, it is possible to defer or modify pharyngeal surgical intervention that may further impair velopharyngeal function in susceptible patients. In this report, we introduce transillumination of the soft palate using a transnasal or transoral flexible endoscope as an inexpensive and simple technique for identification of submucous cleft palate. The use of transillumination of an occult submucous cleft palate is illustrated in a patient case and is compared to other current diagnostic methodologies.