Gramicidin, a Bactericidal Antibiotic, Is an Antiproliferative Agent for Ovarian Cancer Cells.

Background and Objectives: Gramicidin, a bactericidal antibiotic used in dermatology and ophthalmology, has recently garnered attention for its inhibitory actions against cancer cell growth. However, the effects of gramicidin on ovarian cancer cells and the underlying mechanisms are still poorly understood. We aimed to elucidate the anticancer efficacy of gramicidin against ovarian cancer cells. Materials and Methods: The anticancer effect of gramicidin was investigated through an in vitro experiment. We analyzed cell proliferation, DNA fragmentation, cell cycle arrest and apoptosis in ovarian cancer cells using WST-1 assay, terminal deoxynucleotidyl transferase dUTP nick and labeling (TUNEL), DNA agarose gel electrophoresis, flow cytometry and western blot. Results: Gramicidin treatment induces dose- and time-dependent decreases in OVCAR8, SKOV3, and A2780 ovarian cancer cell proliferation. TUNEL assay and DNA agarose gel electrophoresis showed that gramicidin caused DNA fragmentation in ovarian cancer cells. Flow cytometry demonstrated that gramicidin induced cell cycle arrest. Furthermore, we confirmed via Western blot that gramicidin triggered apoptosis in ovarian cancer cells. Conclusions: Our results strongly suggest that gramicidin exerts its inhibitory effect on cancer cell growth by triggering apoptosis. Conclusively, this study provides new insights into the previously unexplored anticancer properties of gramicidin against ovarian cancer cells.

Gramicidin S and melittin: potential anti-viral therapeutic peptides to treat SARS-CoV-2 infection.

The COVID19 pandemic has led to multipronged approaches for treatment of the disease. Since de novo discovery of drugs is time consuming, repurposing of molecules is now considered as one of the alternative strategies to treat COVID19. Antibacterial peptides are being recognized as attractive candidates for repurposing to treat viral infections. In this study, we describe the anti-SARS-CoV-2 activity of the well-studied antibacterial peptides gramicidin S and melittin obtained from Bacillus brevis and bee venom respectively. The EC50 values for gramicidin S and melittin were 1.571 µg and 0.656 µg respectively based on in vitro antiviral assay. Significant decrease in the viral load as compared to the untreated group with no/very less cytotoxicity was observed. Both the peptides treated to the SARS-CoV-2 infected Vero cells showed viral clearance from 12 h onwards with a maximal viral clearance after 24 h post infection. Proteomics analysis indicated that more than 250 proteins were differentially regulated in the gramicidin S and melittin treated SARS-CoV-2 infected Vero cells against control SARS-CoV-2 infected Vero cells after 24 and 48 h post infection. The identified proteins were found to be associated in the metabolic and mRNA processing of the Vero cells post-treatment and infection. Both these peptides could be attractive candidates for repurposing to treat SARS-CoV-2 infection.

Glycolysis regulates Hedgehog signalling via the plasma membrane potential.

Changes in cell metabolism and plasma membrane potential have been linked to shifts between tissue growth and differentiation, and to developmental patterning. How such changes mediate these effects is poorly understood. Here, we use the developing wing of Drosophila to investigate the interplay between cell metabolism and a key developmental regulator-the Hedgehog (Hh) signalling pathway. We show that reducing glycolysis both lowers steady-state levels of ATP and stabilizes Smoothened (Smo), the 7-pass transmembrane protein that transduces the Hh signal. As a result, the transcription factor Cubitus interruptus accumulates in its full-length, transcription activating form. We show that glycolysis is required to maintain the plasma membrane potential and that plasma membrane depolarization blocks cellular uptake of N-acylethanolamides-lipoprotein-borne Hh pathway inhibitors required for Smo destabilization. Similarly, pharmacological inhibition of glycolysis in mammalian cells induces ciliary translocation of Smo-a key step in pathway activation-in the absence of Hh. Thus, changes in cell metabolism alter Hh signalling through their effects on plasma membrane potential.

Building upon Nature's Framework: Overview of Key Strategies Toward Increasing Drug-Like Properties of Natural Product Cyclopeptides and Macrocycles.

The pharmaceutical industry has focused mainly in the development of small-molecule entities intended for oral administration for the past decades. As a result, the majority of existing drugs address only a narrow range of biological targets. In the era of post-genomics, transcriptomics, and proteomics, there is an increasing interest on larger modulators of proteins that can span larger surfaces, access new therapeutic mechanisms of action, and provide greater target specificity. Traditional drug-like molecules developed using "rule-of-five" (Ro5) guidelines have been proven ineffective against a variety of challenging targets, such as protein-protein interactions, nucleic acid complexes, and antibacterial modalities. However, natural products are known to be effective at modulating such targets, leading to a renewed focus by medicinal chemists on investigating underrepresented chemical scaffolds associated with natural products. Here we describe recent efforts toward identification of novel natural cyclopeptides and macrocycles as well as selected medicinal chemistry strategies to increase drug-like properties or further exploration of their activity.

Current Trends in the Use of Two Combination Antifungal/Corticosteroid Creams.

Superficial fungal infections are among the most commonly managed skin problems by general practitioners. Although evidence shows combination antifungal/corticosteroid topicals are more expensive and less effective than single-agent antifungals, practitioners continue to prescribe combination agents. We examined current prescription trends of 2 combination antifungal/corticosteroid medications, Lotrisone and Mycolog-II.

Multidisciplinary care of a paediatric patient with Gradenigo's syndrome.

A 10-year-old girl presented with signs and symptoms suggestive of Gradenigo's syndrome, a condition characterised by otorrhoea, diplopia due to abducens nerve palsy and pain in the region of the trigeminal nerve. This case examines the presentation of this condition, and the appropriate investigations. We also highlight the importance of the involvement of multiple specialities in discussing and devising a suitable management plan.

Irritation and allergy patch test analysis of topical treatments commonly used in wound care: evaluation on normal and compromised skin.

BACKGROUND: Topical agents indicated for the treatment of superficial wounds have the potential to cause irritation or allergic contact dermatitis, particularly when applied to an impaired skin barrier. OBJECTIVE: We sought to compare the irritancy potential of 5 topical wound care products commonly used in dermatologic practice on normal and compromised skin. METHODS: Agents tested included Aquaphor Healing Ointment (AHO) (Beiersdorf Inc, Wilton, CT); bacitracin; Biafine Topical Emulsion (BTE) (OrthoNeutrogena, Los Angeles, CA); Neosporin (Poly/Bac/Neo) (Johnson & Johnson, New Brunswick, NJ); and Polysporin (Poly/Bac) (Johnson & Johnson). Study 1 assessed cumulative irritation using a modified human repeat insult patch test on normal back skin with an induction phase (test materials applied under occlusive patch 9 times at 48- to 72-hour intervals) and a challenge phase (test materials applied to original and naïve sites for 48 hours, 12-24 days postinduction). Irritation was graded for erythema and type IV allergy skin responses. Study 2 assessed the acute irritation potential of agents on tape-stripped ("wounded") back skin. Test sites were graded for erythema, transepidermal water loss, and skin color (Chroma Meter a∗) (Minolta, Osaka, Japan) at 48 and 72 hours poststripping. RESULTS: In study 1, cumulative irritation testing in 108 subjects classified AHO, bacitracin, Poly/Bac/Neo, and Poly/Bac as "mild," and BTE as "probably mild." In study 2 at 72 hours, mean clinical grading scores were significantly higher for BTE and Poly/Bac/Neo than AHO. Transepidermal water loss and colorimeter a∗ values were significantly lower for AHO and bacitracin compared with BTE. No allergic contact dermatitis was seen in either study. CONCLUSIONS: Patch test studies demonstrated that BTE showed the greatest irritancy potential in both normal and compromised skin whereas AHO showed the least.

Postprocedural wound-healing efficacy following removal of dermatosis papulosa nigra lesions in an African American population: a comparison of a skin protectant ointment and a topical antibiotic.

BACKGROUND: Removal of dermatosis papulosa nigra (DPN) lesions results in superficial cutaneous wounds that are frequently treated with topical antibiotic ointments. We hypothesize that antibiotics are not necessary for effective and safe healing of such wounds. OBJECTIVE: This study compared the wound healing efficacy and safety of the skin protectant Aquaphor Healing Ointment (AHO) (Beiersdorf Inc, Wilton, CT) and Polysporin first-aid ointment (Poly/Bac) (polymyxin B sulfate/bacitracin zinc) (Johnson & Johnson, New Brunswick, NJ) after removal of DPN lesions. METHODS: This double-blind, split-face, pilot study removed two DPN lesions from each side of the face of 20 African American subjects. Wounds on opposite sides of the face were treated with AHO or Poly/Bac twice daily for 21 days. Wounds were evaluated for erythema, edema, crusting, scabbing, epithelial confluence, melanin confluence, general wound appearance, and subjective irritation on days 1, 3, 7, 10, 14, and 21 after surgery using 5-point scales. RESULTS: Wound healing parameter assessments showed no differences between wounds treated with AHO versus Poly/Bac in erythema, edema, epithelial confluence, crusting, scabbing, melanin confluence, or postinflammatory hyperpigmentation at any time point. Subjective irritation was similar between treatments for burning, stinging, itching, tightness, tingling, and pain. No adverse events were reported. LIMITATIONS: This was a small study in a homogenous population of African Americans. CONCLUSIONS: Postprocedural treatment with AHO and Poly/Bac demonstrated equivalent wound healing in an African American population. These results support the hypothesis that antibiotics are not necessary for safe and effective healing of facial wounds resulting from removal of DPN lesions.

Long-term follow-up of the Hemodialysis Infection Prevention with Polysporin Ointment (HIPPO) Study: a quality improvement report.

BACKGROUND: Infection is a common and serious complication in hemodialysis patients accessed using central venous catheters (CVCs). Previously, a randomized double-blinded trial (HIPPO [Hemodialysis Infection Prevention With Polysporin Ointment] Study) showed that application of a topical polyantibiotic ointment at the CVC exit site decreased CVC-related infections, including bacteremias and their adverse consequences. Based on this study's results, our institution implemented a policy of routine topical polyantibiotic ointment application for CVC-related infection prophylaxis. The main purpose of this prospective observational study was to determine whether the low rate of CVC-related infection achieved by topical polyantibiotic ointment use during a randomized controlled trial would be observed during long-term prophylaxis as part of routine clinical care. STUDY DESIGN: Quality improvement report. SETTING & PARTICIPANTS: All adult long-term hemodialysis patients using a tunneled cuffed CVC in a large university-affiliated outpatient hemodialysis program in 2004-2009 were included. QUALITY IMPROVEMENT PLAN: To prospectively monitor the impact of a policy-wide strategy of topical polyantibiotic ointment application at CVC exit sites (1 time/wk) as infection prophylaxis. A multidisciplinary team approach to the surveillance, prospective tracking, and management of hemodialysis CVC-related infection was used. OUTCOMES & MEASUREMENTS: Rates of CVC-related infections (exit-site infections and bacteremias), percentages of contributing organisms, and consequences of CVC-related infections. RESULTS: After 6 years, CVC exit-site infection and bacteremia rates remained low (<1.0/1,000 catheter-days). Gram-positive organisms accounted for 61.2% of exit-site infections and 72.1% of bacteremias. LIMITATIONS: A center effect of the same institution conducting the randomized trial and the quality improvement study may limit the study's generalizability to other centers. The impact of possible unmeasured cointerventions cannot be excluded. CONCLUSION: Long-term use of topical antibiotic application at CVC exit sites resulted in a sustained decrease in all CVC-related infections. A multidisciplinary effort to monitor and track outcomes allowed safe and effective implementation of a new prophylactic strategy.

Interventions for preventing infectious complications in haemodialysis patients with central venous catheters.

BACKGROUND: Central venous catheters (CVC) continue to play a prominent role in haemodialysis vascular access with 46% to 70% of patients commencing haemodialysis via a CVC. CVC access is associated with catheter-related infections, increased patient hospitalisations and death due to infection. A variety of interventions are used to prevent CVC infection. OBJECTIVES: To evaluate the benefits and harms of prophylactic topical antimicrobials, topical antiseptics, medicated and non-medicated dressings on infectious complications among haemodialysis patients with CVC. SEARCH STRATEGY: We searched the Cochrane Renal Group's specialised register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and reference lists of articles without language restriction. SELECTION CRITERIA: We included randomised controlled trials (RCTs) and quasi-RCTs investigating any intervention that prevented infectious complications among haemodialysis patients with CVC. We excluded antimicrobial impregnated CVC or CVC using locking solutions with antimicrobial properties. DATA COLLECTION AND ANALYSIS: Two authors assessed study quality and extracted data. Dichotomous outcomes were expressed as risk ratios (RR) with 95% confidence intervals (CI) and continuous outcomes as mean differences (MD). MAIN RESULTS: Ten studies (786 patients) were included. Mupirocin ointment reduced the risk of catheter-related bacteraemia (RR 0.17, 95%CI 0.07 to 0.43) and had a significant effect on catheter-related infections caused by S. aureus. The risk of catheter-related bacteraemia was reduced by polysporin (RR 0.40, 95%CI 0.19 to 0.86) and povidone-iodine ointment (RR 0.10, 95%CI 0.01 to 0.72). Subgroup analysis suggested mupirocin (RR 0.12, 95%CI 0.01 to 2.13) and povidone-iodine ointment (RR 0.84, 95%CI 0.24 to 2.98) had no effect on all-cause mortality while polysporin ointment showed a significant reduction (RR 0.22, 95%CI 0.07 to 0.74). Mortality related to infection was not reduced by mupirocin, polysporin or povidone-iodine ointment. Topical honey did not reduce the risk of exit site infection (RR 0.45, 95%CI 0.10 to 2.11) or catheter-related bacteraemia (RR 0.80, 95%CI 0.37 to 1.73). Transparent polyurethane dressing compared to dry gauze dressing did not reduce the risk of CVC or exit site infection, or catheter-related bacteraemia. AUTHORS' CONCLUSIONS: Mupirocin ointment appears effective in reducing the risk of catheter-related bacteraemia. Insufficient reporting on mupirocin resistance was noted and needs to be considered in future studies. A lack of high quality data on the routine use of povidone-iodine ointment, polysporin ointment and topical honey warrant larger RCTs. Insufficient data were available to determine which dressing type (transparent polyurethane or dry gauze dressing) has the lowest risk of catheter-related infections.

Therapeutic index of gramicidin S is strongly modulated by D-phenylalanine analogues at the beta-turn.

Analogues of the cationic antimicrobial peptide gramicidin S (GS), cyclo(Val-Orn-Leu-D-Phe-Pro)2, with d-Phe residues replaced by different (restricted mobility, mostly) surrogates have been synthesized and used in SAR studies against several pathogenic bacteria. While all D-Phe substitutions are shown by NMR to preserve the overall beta-sheet conformation, they entail subtle structural alterations that lead to significant modifications in biological activity. In particular, the analogue incorporating D-Tic (1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid) shows a modest but significant increase in therapeutic index, mostly due to a sharp decrease in hemolytic effect. The fact that NMR data show a shortened distance between the D-Tic aromatic ring and the Orn delta-amino group may help explain the improved antibiotic profile of this analogue.

Topical ciprofloxin versus topical framycetin-gramicidin-dexamethasone in Australian aboriginal children with recently treated chronic suppurative otitis media: a randomized controlled trial.

BACKGROUND: Chronic suppurative otitis media (CSOM) affects many children in disadvantaged populations. The most appropriate topical antibiotic treatment in children with persistent disease is unclear. METHODS: Children with CSOM despite standard topical treatment were randomized to 6-8 weeks of topical ciprofloxacin (CIP) versus topical framycetin-gramicidin-dexamethasone (FGD). Otoscopic, audiologic, and microbiologic outcomes were measured using standardized assessments and blinding. RESULTS: Ninety-seven children were randomized. Ear discharge failed to resolve at the end of therapy in 70% children regardless of allocation [risk difference = -2%; (95% CI: -20 to 16)]. Healing of the tympanic membrane occurred in one of 50 children in the CIP group and none of 47 children in the FGD group. Severity of discharge failed to improve in more than 50% children in each group, and mean hearing threshold (38 dB and 35 dB) and proportion of children with greater than 25 dB hearing loss (98% and 88%) were not significantly different between the CIP and FGD groups. Side effects were rare. CONCLUSIONS: This study showed a similarly low rate of improvement or cure in children with persistent CSOM for both CIP and FGD topical therapies. Complications and side effects were insufficient to cease therapy or inform prescribing of either therapy.

A randomized controlled trial comparing mupirocin versus Polysporin Triple for the prevention of catheter-related infections in peritoneal dialysis patients (the MP3 study).

BACKGROUND: Peritonitis remains the most serious complication of peritoneal dialysis (PD). Gram-positive organisms are among the most common causes of PD peritonitis; however, recent trends show increasing rates of gram-negative and fungal infections. Strategies to prevent peritonitis include the use of prophylactic topical mupirocin at the site where the PD catheter exits from the abdominal wall; however, mupirocin does not afford protection against gram-negative or fungal infections. The aim of this study is to determine if the incidence of catheter-related infections (exit-site infection, tunnel infection, or peritonitis) is significantly reduced by the routine application of Polysporin Triple antibiotic ointment (Pfizer Canada, Markham, Ontario, Canada) in comparison to mupirocin ointment. METHODS AND DESIGN: The Mupirocin Versus Polysporin Triple Study (MP3) is a multicenter, randomized, double-blinded controlled study comparing Polysporin Triple (P3) against the current standard of care. The aim of the study is to recruit 200 patients being treated with or starting on PD and randomize them to receive either mupirocin or P3 at the catheter exit site. Patients will be followed for 18 months or until death or transfer from PD to an alternate treatment modality. The primary outcome will be the time to first catheter-related infection. Catheter-related infections will be strictly defined using current guidelines and categorized into exit-site infections, infective peritonitis, or tunnel infections. The primary analysis will be an intention-to-treat analysis. DISCUSSION: The results of this study will help determine if the use of P3 is superior to mupirocin ointment in the prevention of catheter-related infections and will help guide evidence-based best practices.

Treatment with a novel hemigramicidin-TEMPO conjugate prolongs survival in a rat model of lethal hemorrhagic shock.

OBJECTIVE: We sought to develop a therapeutic agent that would permit prolongation of survival in rats subjected to lethal hemorrhagic shock (HS), even in the absence of resuscitation with asanguinous fluids or blood. METHODS AND RESULTS: We synthesized a series of compounds that consist of the electron scavenger and superoxide dismutase mimic, 4-amino-2,2,6,6-tetramethylpiperidine-N-oxyl (4-NH2-TEMPO), conjugated to fragments and analogs of the membrane-active cyclopeptide antibiotic, gramicidin S. Using an in vivo assay, wherein isolated intestinal segments were loaded inside the lumen with various test compounds, we studied these compounds for their ability to prevent ileal mucosal barrier dysfunction induced by subjecting rats to profound HS for 2 hours. The most active compound in this assay, XJB-5-131, ameliorated peroxidation of the mitochondrial phospholipid, cardiolipin, in ileal mucosal samples from rats subjected to HS. XJB-5-131 also ameliorated HS-induced activation of the pro-apoptotic enzymes, caspases 3 and 7, in ileal mucosa. Intravenous treatment with XJB-5-131 (2 micromol/kg) significantly prolonged the survival of rats subjected to profound blood loss (33.5 mL/kg) despite administration of only a minimal volume of crystalloid solution (2.8 mL/kg) and the absence of blood transfusion. CONCLUSION: These data support the view that mitochondrially targeted electron acceptors and SOD mimics are potentially valuable therapeutics for the treatment of serious acute conditions, such as HS, which are associated with marked tissue ischemia.

Myringoplasty: a comparison of bismuth iodoform paraffin paste gauze pack and tri-adcortyl ointment ear dressing.

OBJECTIVES: To assess the myringoplasty graft take rate, comparing two methods of post-operative ear packing: bismuth iodoform paraffin paste (BIPP) gauze versus tri-adcortyl ointment (TAO). METHODS: A retrospective study of patients who had undergone myringoplasty at our department within a three-year period was undertaken. Data, including age, site and size of perforation, grade of surgeon, surgical approach, use of post-operative ear dressings, complications, and audiometric outcome, were collected from the patient notes and analysed. The overall success rate of the operation (with success being defined as an intact tympanic membrane at six months) was noted. RESULTS: One hundred and seventy myringoplasties were performed over the study period, but data were complete on 154 patients and these constituted the study population. Age ranged from nine to 71 years (mean age 34 years) and the mean follow-up period was seven months. Consultants performed 62 per cent of the operations, with an 85 per cent success rate, whereas trainees performed the remaining 38 per cent, with a success rate of 73 per cent (p=0.059). The overall success rate was 80 per cent; 79 per cent for BIPP and 83 per cent for TAO (p=0.55), and 87 per cent for small perforations and 75 per cent for subtotal perforations (p=0.22). There was audiometric improvement in 74 per cent of cases. CONCLUSION: We found no significant difference in outcome between patients packed with TAO and BIPP. Packing with TAO is therefore a suitable alternative to BIPP gauze ear dressing following myringoplasty.

Observational study of bone-anchored hearing aid infection rates using different post-operative dressings.

INTRODUCTION: Avoidance of infection at the implant site is a crucial element to the success of bone-anchored hearing aid (BAHA) implantation. However, little evidence exists to suggest the best post-operative wound dressing to use. MATERIAL AND METHODS: We report our experience with 160 consecutive BAHA patients, using four types of post-operative BAHA wound dressing (Tri-adcortyl, Mepitel, Allevyn, and Acticoat 7 with Allevyn). Patients were reviewed at week one and week two post-operatively. Infection was defined as a positive wound swab culture or evidence of cellulitis at the BAHA site. RESULTS: Post-operative BAHA infection rates were 16 per cent, 50 per cent, 10 per cent and 5 per cent, for each of the four dressings respectively, and the mean number of additional visits to wound care clinic were 1.5, 3.7, one and 0.4, respectively. DISCUSSION: Acticoat 7 with Allevyn produced the lowest infection rate and thus became the dressing of choice for our BAHA programme.

Alternative therapies in antibiotic-resistant infection.

CASE REPORT: A 24-year-old woman suffering from post-influenza otitis media infection was initially treated with several series of a steroid (Elocon) and a combination of steroids and antibiotics (Atecortin, Dicortineff) without significant medical benefit. The isolated bacterial strains were identified as Staphylococcus homis and Staphylococcus epidermidis. Specific phage therapy applied sequentially over a period of three weeks resulted only in a partial reduction in inflammation and limited improvement in overall health condition. Oral application of lactoferrin (LF; 50-mg daily oral doses for seven days with two-week intervals) led to a complete clearance of both bacterial strains and full recovery of the patient. The recovery was associated with increased myelopoiesis and a sustained elevation of serum endogenous LF. In conclusion, specific bacteriophage therapy combined with the administration of lactoferrin proved to be effective in the treatment of antibiotic-resistant external ear infection.

Effectiveness of combined antibiotic ophthalmic solution in the treatment of hordeolum after incision and curettage: a randomized, placebo-controlled trial: a pilot study.

The presented pilot study compared the effectiveness of combined antibiotic ophthalmic solution (neomycin sulfate, polymyxin B sulfate and gramicidin) with a placebo (artificial tear) in the treatment of hordeolum after incision and curettage (I&C). A randomized, placebo-controlled trial with patients and investigators blinded from the start started from June 2002 to May 2003. Subjects were patients with untreated hordeolum who subsequently underwent I&C at the Ophthalmology Department. The patients were randomized into 2 groups: group A for combined antibiotic ophthalmic solution, and group B for artificial tear containing the antibiotic solution base. Pain score, mass size and duration of cure were recorded before and on the 3rd and 7th day after treatment. The study included 14 patients in each group. Two subjects in group A and three subjects in group B dropped out. There were no statistically significant differences of all outcomes in both groups, even with the intention-to-treat analysis. The conclusion is combined antibiotic ophthalmic solution is not more effective than placebo in the treatment of hordeolum after I&C.