A comparative review of cutaneous pH

Fluctuations in equine cutaneous pH and transepidermal water loss with time of day and ambient conditions

Cutaneous pH and transepidermal water loss (TEWL) are commonly utilized measures in dermatological research as they provide information concerning barrier function. The importance of dermal health has become more evident in recent years. Accordingly, the aim of this work was to identify natural fluctuations in the biophysical parameters of healthy equine skin. Cutaneous pH and TEWL was collected on nine mares at 6:00 AM, 12:00 PM, and 6:00 PM daily for five days on the nose, withers, girth area, mid-back, and base of tail. Ambient temperature and humidity were measured at each collection. Statistical analysis was completed using SAS On Demand. Tests included repeated measures, ANOVA, and regression analysis. Mean cutaneous pH significantly differed by day (P = 0.0052) and time (P = 0.0073) but was unaffected by anatomical location (P = 0.2841). Interestingly, cutaneous pH had a significant interaction of day and location (P = 0.0004). Mean TEWL measures significantly differed by day (P < 0.0001), time (P < 0.0001), and anatomical location (P = 0.0231). Interaction of day and time had a significant effect on TEWL (P < 0.0001) and also resulted in a three-way interaction of day, time, and location (P = 0.0167). There were no significant associations of pH with temperature and humidity. All measures of TEWL across all locations were significantly correlated with temperature and humidity (P < 0.0001). Cutaneous pH and TEWL measures are affected by environmental conditions which should be considered in future models and work using dermal characteristics of horses.

Nanozymes for the Therapeutic Treatment of Diabetic Foot Ulcers

Diabetic foot ulcers (DFU) are chronic, refractory wounds caused by diabetic neuropathy, vascular disease, and bacterial infection, and have become one of the most serious and persistent complications of diabetes mellitus because of their high incidence and difficulty in healing. Its malignancy results from a complex microenvironment that includes a series of unfriendly physiological states secondary to hyperglycemia, such as recurrent infections, excessive oxidative stress, persistent inflammation, and ischemia and hypoxia. However, current common clinical treatments, such as antibiotic therapy, insulin therapy, surgical debridement, and conventional wound dressings all have drawbacks, and suboptimal outcomes exacerbate the financial and physical burdens of diabetic patients. Therefore, development of new, effective and affordable treatments for DFU represents a top priority to improve the quality of life of diabetic patients. In recent years, nanozymes-based diabetic wound therapy systems have been attracting extensive interest by integrating the unique advantages of nanomaterials and natural enzymes. Compared with natural enzymes, nanozymes possess more stable catalytic activity, lower production cost and greater maneuverability. Remarkably, many nanozymes possess multienzyme activities that can cascade multiple enzyme-catalyzed reactions simultaneously throughout the recovery process of DFU. Additionally, their favorable photothermal-acoustic properties can be exploited for further enhancement of the therapeutic effects. In this review we first describe the characteristic pathological microenvironment of DFU, then discuss the therapeutic mechanisms and applications of nanozymes in DFU healing, and finally, highlight the challenges and perspectives of nanozyme development for DFU treatment.

Nanocomposite Gels Loaded with Flurbiprofen: Characterization and Skin Permeability Assessment in Different Skin Species

Nanocomposite gels consist of nanoparticles dispersed in a gel matrix. The main aim of this work was to develop nanocomposite gels for topical delivery of Flurbiprofen (FB) for humans and farm animals. Nanocomposite gels were prepared stemming from nanoparticles (NPs) freeze-dried with two different cryoprotectants, D-(+)-trehalose (NPs-TRE) and polyethylene glycol 3350 (NPs-PEG), sterilized by gamma (γ) irradiation, and gelled with Sepigel® 305. Nanocomposite gels with FB-NPs-TRE and FB-NPs-PEG were physiochemically characterized in terms of appearance, pH, morphological studies, porosity, swelling, degradation, extensibility, and rheological behavior. The drug release profile and kinetics were assessed, as well as, the ex vivo permeation of FB was assessed in human, porcine and bovine skin. In vivo studies in healthy human volunteers were tested without FB to assess the tolerance of the gels with nanoparticles. Physicochemical studies demonstrated the suitability of the gel formulations. The ex vivo skin permeation capacity of FB-NPs nanocomposite gels with different cryoprotectants allowed us to conclude that these formulations are suitable topical delivery systems for human and veterinary medicine. However, there were statistically significant differences in the permeation of each formulation depending on the skin. Results suggested that FB-NPs-PEG nanocomposite gel was most suitable for human and porcine skin, and the FB-NPs-TRE nanocomposite gel was most suitable for bovine skin.

Screen-printed wearable skin surface pH sensor for real-time monitoring of the buffering capacity of human skin

This study demonstrated for the first time that skin surface pH can be monitored in real-time, using a screen-printed wearable pH sensor, to evaluate the buffering capacity of the human skin. The screen-printed pH sensor was composed of a polyaniline-based pH-sensitive electrode and a nitrocellulose membrane-based liquid junction type of Ag/AgCl reference electrode. This sensor showed a reliable and reversible potentiometric response to pH with long-term potential stability. Intermittent monitoring of the buffering capacity of skin surface pH demonstrated the reliability of the proposed wearable pH sensor, which was comparable to that of a commercially available flat-tip pH sensor. We found that contact of the wearable pH sensor with the subject's skin via aqueous electrolyte solutions was necessary for the sensor to continuously monitor the skin surface pH while sustaining the natural buffer capacity of the human skin surface.

Pharmacotechnical aspects of a stable probiotic formulation toward multidrug-resistance antibacterial activity: design and quality control

As a well-known group of the probiotic family, the Lactobacillus has increasingly contributed to hindering the growth of pathogens, particularly resistant species, in the last decades. Since antibiotic resistance has become a severe problem in global healthcare systems and considerably increased the mortality and morbidity rate in infectious diseases, we aimed to obtain a new stable formulation of Lactobacillus to overcome resistant infections. For this purpose, we designed various gel formulations containing Lactobacillus rhamnosus (L. rhamnosus) as an active pharmaceutical ingredient (API) in a water base and oil base gel, evaluated the probiotic stability in formulation to obtain an optimum formulation, and finally, investigated the antibacterial activities of that against two common hospital-associated multidrug-resistant pathogens, methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus (VRE). Furthermore, the pharmaceutical aspects of the optimum formulation, including stability, homogeneity, spreadability, pH value, conductivity, and rheological behavior, were assessed.The results indicated that the optimum formulation based on glycerol exhibited desirable pharmaceutical properties, including long-term stability, a perfect level of homogeneity, an acceptable range of spreadability with pseudo-plastic thixotropic behavior, and a promising antibacterial potential against MRSA and VRE. Our findings indicate that this novel probiotic formulation could be an excellent candidate to cope with antibiotic-resistant species, representing a hopeful treatment potential for topical applications, particularly in incurable infections. However, further in vivo studies seem warranted to evaluate their bactericidal activity against multi-drug resistant microorganisms.

Meta-analysis Investigating the Efficacy of Liquid Dressing and Ostomy Powder for the Treatment of Incontinence-Associated Dermatitis

OBJECTIVE

To study the effect of liquid dressing and ostomy powder on the treatment of incontinence-associated dermatitis (IAD).

METHODS

The authors searched PubMed, Web of Science, CNKI (China National Knowledge Internet), and Google Scholar databases for literature through July 28, 2022. After literature screening, two investigators independently extracted data from the included studies and applied the Newcastle-Ottawa Scale to assess the quality of the included studies. The χ2-based Q statistic test and the I2 statistic were used to measure the heterogeneity of the included studies. Publication bias was measured with funnel plots and the Egger test. Sensitivity analysis was conducted by eliminating each study one by one.

RESULTS

Four high-quality studies were included in the meta-analysis, involving a total of 307 participants. The meta-analysis results showed that compared with traditional care, treatment with liquid dressing and ostomy powder significantly improved the effective rate (pooled odds ratio, 21.42; 95% CI, 8.58 to 53.44), shortened the healing time (pooled mean difference, -10.73; 95% CI, -12.92 to -8.54), and reduced the recurrence rate (pooled mean difference, -2.03; 95% CI, -2.30 to -1.77) of IAD. Among the included studies, no publication bias was detected. Sensitivity analysis results confirmed the robustness of the pooled estimates.

CONCLUSIONS

Treatment with liquid dressing and ostomy powder has clinical value for patients with IAD.

Impacts to canine dermal microbiota associated with repeated bathing

Introduction

Working dogs routinely operate in environmental conditions which may necessitate daily bathing to remove contaminants or soilage. The impacts of frequent or repeated bathing on the canine dermal microbiota are unknown. The objective of this study was to characterize changes in canine dermal microbial populations following repeated daily bathing.

Methods

Labrador retrievers (n = 16) were bathed daily using a dilute dish detergent solution (1.6% detergent solution) over the course of 14 days. Dermal microbial DNA was collected via sterile swabs (n = 142) taken at days 0, 7, 14, 16, 21, 28, 35, 42, and 49 and analyzed for alpha diversity, beta diversity and relative abundance to assess changes in the dermal microbiota via 16 s sequencing.

Results

Results indicate that daily bathing significantly increased Shannon diversity, Chao1, and several rare amplicon sequence variants. Although typically reported in highest abundance, relative abundance was decreased in the phyla Actinobacteria, Firmicutes, and Proteobacteria (p < 0.05).

Conclusion

Repeated daily bathing with dilute dish detergent significantly reduced normal healthy dermal microbial taxa and created significant changes in the dermal microbiota of canines. Disruption to the canine dermal microbiota may cause negative impacts to canine dermal health and require further investigation.

Preclinical Considerations for Long-acting Delivery of Tenofovir Alafenamide from Subdermal Implants for HIV Pre-exposure Prophylaxis

PURPOSE

Long-acting formulations of the potent antiretroviral prodrug tenofovir alafenamide (TAF) hold potential as biomedical HIV prevention modalities. Here, we present a rigorous comparison of three animal models, C57BL/6 J mice, beagle dogs, and merino sheep for evaluating TAF implant pharmacokinetics (PKs).

METHODS

Implants delivering TAF over a wide range of controlled release rates were tested in vitro and in mice and dogs. Our existing PK model, supported by an intravenous (IV) dosing dog study, was adapted to analyze mechanistic aspects underlying implant TAF delivery.

RESULTS

TAF in vitro release in the 0.13 to 9.8 mg d-1 range with zero order kinetics were attained. Implants with equivalent fabrication parameters released TAF in mice and sheep at rates that were not statistically different, but were 3 times higher in dogs. When two implants were placed in the same subcutaneous pocket, a two-week creep to Cmax was observed in dogs for systemic drug and metabolite concentrations, but not in mice. Co-modeling IV and TAF implant PK data in dogs led to an apparent TAF bioavailability of 9.6 in the single implant groups (compared to the IV group), but only 1.5 when two implants were placed in the same subcutaneous pocket.

CONCLUSIONS

Based on the current results, we recommend using mice and sheep, with macaques as a complementary species, for preclinical TAF implant evaluation with the caveat that our observations may be specific to the implant technology used here. Our report provides fundamental, translatable insights into multispecies TAF delivery via long-acting implants.

Determination of Selected Harmful Substances in Baby Diapers Available on the South African Market

Baby diaper rash is a common problem, especially allergic contact dermatitis, which could be due to heavy metals, pH, formaldehyde, or allergens in the diapers. This study reports on the determination of formaldehyde, heavy metals (Pb, As, Co, Cr, Ni, Cu, Zn, Mn, Sr, Fe, and Cd), and pH in diapers purchased from low-, medium-, and high-end stores. Inductively coupled plasma was used to determine the concentrations of heavy metals after extraction using artificial urine and artificial sweat. All heavy metals were found in all diapers except Sr, which was not found in sample M7. All samples had concentrations of heavy metals within the Oeko-Tex limits, except samples H2 and L2, whose Ni concentrations were above permissible limits. Fifty percent of diapers had a formaldehyde concentration above the Oeko-Tex recommended limits. The highest formaldehyde concentration of 17.62 mg/kg was found in diaper M2 and the lowest (ca. 10.4 mg/kg) in H1. All samples had pH values in the alkaline region, with only five samples having pH values within the recommended limits. The research concluded that the diaper rash experienced by some babies, among other factors, could be due to high alkaline skin pH and formaldehyde levels, which are higher than the Oeko-Tex recommended limits.

A comparison of canine decontamination cleansers: Implications for water use, dermal pH, and contaminant reduction

Environmental contamination is commonly experienced by working canines deployed in the field. Unfortunately, data regarding safety and efficacy of cleansers recommended for decontamination is lacking. Client-owned canines recruited from the community (n = 43) were randomly assigned to one of four treatment groups: povidone-iodine scrub [60mL Betadine® 7.5% povidone-iodine surgical scrub (Avrio Health L.P, Stamford, CT)], chlorhexidine scrub [60 mL Nolvasan® 2% chlorohexidine surgical scrub (Zoetis, Kalamazoo, MI)], dish detergent [60mL Dawn® dish detergent (Proctor & Gamble, Cincinnati, OH)], or water alone (control). A visual score assessing removal of a fluorescent marker (GloGerm, Moab, UT) applied between the shoulder blades was used to rate effectiveness of decontamination. Cleanser effect on canine dermal barrier function was determined by measuring pre- and post-decontamination dermal pH and trans-epidermal water loss (TEWL). Analysis of visual scores was performed using PROC FREQ and Chi Square. Significance was set a priori at 0.05 for all tests. Efficacy of fluorescent marker removal was significantly affected by cleanser (P<0.0001). Dermal pH was also highly affected by cleanser (P < 0.0001). In contrast, TEWL was unchanged across cleansers (P = 0.2686). Common veterinary cleansers utilized for canine decontamination demonstrate similarity in effectiveness for removal of a simulated contaminant and negative impact on dermal barrier function.

Effect of an ear cleaner instillation containing lipacids in a model of re-acidification of the external auditory canal in dogs

Background

In humans, the acidic pH of the ear canal plays a protective role against infection and a change towards alkalinity of the external auditory canal (EAC) is a local factor in the progression of acute to chronic otitis externa (OE). The use of acidic preparations alone for treatment of OE without concurrent antibiotic use is well‐documented in humans. In dogs, only one study has investigated the EAC pH in healthy dogs and in dogs with OE, and investigations to understand the role of EAC pH in the pathogenesis of canine OE are lacking.

Hypothesis/objectives

To obtain physiological EAC pH values in beagle dogs. To develop a model of re‐acidification of the EAC in dogs and to investigate how an acidic solution may accelerate the return to a physiological pH.

Animals

Ten healthy beagle dogs in a laboratory setting.

Materials and Methods

A model of re‐acidification of the EAC was developed by instillation of a pH 10.1 phosphate‐buffered saline (PBS) solution and the subsequent acidic effect of an ear cleaner containing lipacids was evaluated in this model.

Results

Mean physiological EAC pH was 6.12 (± 0.36). EAC re‐acidification took up to 9 h in this model. Mean pH values dropped immediately to 6.38 (± 0.27) on ears treated with an acidic ear cleaner. No abrupt drop was observed of the mean pH values for the control ears.

Conclusion and clinical importance

This study confirms that physiological EAC pH in dogs is acidic. This model of re‐acidification of the EAC pH allows investigations on acidic properties of topical ear products in healthy ears.

Background – In humans, the acidic pH of the ear canal plays a protective role against infection and a change towards alkalinity of the auditory canal (EAC) is a local factor in the progression of acute to chronic otitis externa (OE). The use of acidic preparations alone for treatment of OE without concurrent antibiotic use is well‐documented in humans. In dogs, only one study has investigated the EAC pH in healthy dogs and in dogs with OE, and investigations to understand the role of EAC pH in the pathogenesis of canine OE are lacking.

Hypothesis/objectives –To obtain physiological EAC pH values in beagle dogs. To develop a model of re‐acidification of the EAC in dogs and to investigate how an acidic solution may accelerate the return to a physiological pH.

Conclusion and clinical importance – This study confirms that physiological EAC pH in dogs is acidic. This model of re‐acidification of the EAC pH allows investigations on acidic properties of topical ear products in healthy ears.

Manipulating Microbiota to Treat Atopic Dermatitis: Functions and Therapies

Atopic dermatitis (AD) is a globally prevalent skin inflammation with a particular impact on children. Current therapies for AD are challenged by the limited armamentarium and the high heterogeneity of the disease. A novel promising therapeutic target for AD is the microbiota. Numerous studies have highlighted the involvement of the skin and gut microbiota in the pathogenesis of AD. The resident microbiota at these two epithelial tissues can modulate skin barrier functions and host immune responses, thus regulating AD progression. For example, the pathogenic roles of Staphylococcus aureus in the skin are well-established, making this bacterium an attractive target for AD treatment. Targeting the gut microbiota is another therapeutic strategy for AD. Multiple oral supplements with prebiotics, probiotics, postbiotics, and synbiotics have demonstrated promising efficacy in both AD prevention and treatment. In this review, we summarize the association of microbiota dysbiosis in both the skin and gut with AD, and the current knowledge of the functions of commensal microbiota in AD pathogenesis. Furthermore, we discuss the existing therapies in manipulating both the skin and gut commensal microbiota to prevent or treat AD. We also propose potential novel therapies based on the cutting-edge progress in this area.

Application of Levan-Rich Digestate Extract in the Production of Safe-to-Use and Functional Natural Body Wash Cosmetics

The study focused on the evaluation of the possibility of using a levan-rich digestate extract in the production of safe and functional body wash cosmetics. Model shower gels were designed and formulated on the basis of raw materials of natural origin. Prepared prototypes contained various extract concentrations (16.7; 33; 50%). A gel without extract was used as a reference. The samples were evaluated for their safety in use and functionality. The results showed that the use of high-concentration levan-rich digestate extract in a shower gel resulted in a significant reduction in the negative impact on the skin. For example, the zein value decreased by over 50% in relation to the preparation without the extract. An over 40% reduction in the emulsifying capacity of hydrophobic substances was also demonstrated, which reduces skin dryness after the washing process. However, the presence of the extract did not significantly affect the parameters related to functionality. Overall, it was indicated that levan-rich digestate extract can be successfully used as a valuable ingredient in natural cleansing cosmetics.

Skin Barrier Function in Infants: Update and Outlook

A good understanding of infant skin should provide a rationale for optimum management of the health of this integument. In this review, we discuss the skin barrier function of infants, particularly with reference to the use of diapers and baby wipes. The skin barrier of newborns continues to develop with age. Two years after birth, the barrier properties of infant skin closely resemble those of adult skin. However, several risk factors may contribute to impaired skin barrier and altered skin permeability in infants. Problems may arise from the use of diapers and baby wipes. The skin covered by a diaper is effectively an occluded environment, and thus is vulnerable to over-hydration. To date there has been no published information regarding dermal absorption of ingredients contained in baby wipes. Similarly, dermal absorption of topical ingredients in infants with underlying skin conditions has not been widely explored. Clearly, there are serious ethical concerns related to conducting skin permeation studies on infant skin. However, the increasing availability of non-invasive methods for in vivo studies is encouraging and offers new directions for studying this important patient group.

Skin pH varies among bat species and seasons and between wild and captive bats

Skin is a key aspect of the immune system in the defence against pathogens. Skin pH regulates the activity of enzymes produced both by hosts and by microbes on host skin, thus implicating pH in disease susceptibility. Skin pH varies inter- and intra-specifically and is influenced by a variety of intrinsic and extrinsic variables. Increased skin alkalinity is associated with a predisposition to cutaneous infections in humans and dogs, and inter-specific and inter-individual variation in skin pH is implicated in differential susceptibility to some skin diseases. The cutaneous pH of bats has not been characterized but is postulated to play a role in susceptibility to white-nose syndrome (WNS), a fungal infection that has decimated several Nearctic bat species. We used non-invasive probes to measure the pH of bat flight membranes in five species with differing susceptibility to WNS. Skin pH ranged from 4.67 to 8.59 and varied among bat species, geographic locations, body parts, age classes, sexes and seasons. Wild Eptesicus fuscus were consistently more acidic than wild Myotis lucifugus, Myotis leibii and Perimyotis subflavus. Juvenile bats had more acidic skin than adults during maternity season but did not differ during swarming. Male M. lucifugus were more acidic than females during maternity season, yet this trend reversed during swarming. Bat skin was more acidic in summer compared to winter, a pattern also reported in humans. Skin pH was more acidic in captive than wild E. fuscus, suggesting environmental impacts on skin pH. The pH of roosting substrates affects skin pH in captive bats and may partially explain seasonal patterns in wild bats that use different roost types across seasons. Future research on the influence of pH on microbial pathogenic factors and skin barrier function may provide valuable insights on new therapeutic targets for treating bat skin conditions.

Ichthyosis and hereditary cornification disorders in dogs

The stratum corneum (SC), the outermost layer of the epidermis, serves a crucial role in maintaining body hydration and protection from environmental insults. When the stratum corneum is injured or when the genetic blueprints are flawed, the body is at risk of dehydration, secondary infections and allergen sensitization. Advancements in veterinary dermatology have revealed a wide gamut of disease from relatively benign to lethal that specifically arise from flawed structural proteins, enzymes or lipids needed to create the corneocytes and lipid bilayers of the SC. Some conditions closely mimic their human counterparts while others are unique to the dog. This review will focus on forms of ichthyosis in the dog.

Clinical efficacy of artificially carbonated water bathing on superficial bacterial folliculitis in dogs

BACKGROUND

Bathing with artificially carbonated water is reported to be a valuable therapeutic option for various human skin disorders.

OBJECTIVE

To evaluate the clinical efficacy of artificially carbonated water bathing on superficial bacterial folliculitis (SBF) caused by Staphylococcus pseudintermedius (SP) in dogs.

ANIMALS

Nineteen dogs with SBF from whom SP was isolated from skin lesions were enrolled.

METHODS AND MATERIALS

Dogs with SBF were allocated randomly to either the artificially carbonated water bathing group or the control group bathed with tap water. The dogs were bathed with the designated water type on day (D)0, D7 and D14. Clinical scores and skin surface pH were evaluated on D0 and D21. Colony forming unit (cfu) assays were performed in vitro to investigate whether the artificially carbonated water affected growth of clinical SP isolates.

RESULTS

The mean rate of improvement in the clinical scores was significantly higher in the carbonated water group than in the control group. Dogs bathed with carbonated water exhibited significant decreases in their skin surface pH after bathing; dogs bathed with tap water did not. No dogs experienced significant adverse events. The cfus of SP incubated in vitro with artificially carbonated water did not significantly differ from those incubated with tap water.

CONCLUSION

Bathing with artificially carbonated water might be an effective and safe adjunctive therapy for canine SP-induced SBF.

Wolves, dogs and humans in regular contact can mutually impact each other's skin microbiota

In contrast to humans and dogs, the skin microbiota of wolves is yet to be described. Here, we investigated the skin microbiota of dogs and wolves kept in outdoor packs at the Wolf Science Center (WSC) via 16S rRNA gene amplicon sequencing. Skin swab samples were also collected from human care takers and their pet dogs. When comparing the three canine groups, representing different degrees of human contact to the care takers and each other, the pet dogs showed the highest level of diversity. Additionally, while human skin was dominated by a few abundant phylotypes, the skin microbiota of the care takers who had particularly close contact with the WSC animals was more similar to the microbiota of dogs and wolves compared to the humans who had less contact with these animals. Our results suggest that domestication may have an impact on the diversity of the skin microbiota, and that the canine skin microbiota can be shared with humans, depending on the level of interaction.

Influence of age, sex, body condition score, rectal temperature, anatomical location and hair on skin pH in dogs

BACKGROUND

Physiological skin pH levels are well-documented in human medicine, and assessment of variations may be important in assessing the efficacy of wound healing. By contrast, physiological skin pH levels in dogs are sparsely described.

HYPOTHESIS/OBJECTIVES

To determine the pH of intact skin in healthy dogs and to study the influence of different physiological factors on the pH level of canine skin.

ANIMALS

Seventy-seven client-owned dogs of various breeds, age and sex.

METHODS AND MATERIALS

A prospective study was designed and the pH of intact skin was measured at the concave surface of both pinnae, and in both axillary and inguinal regions. For each location, the colour and density of the hairs also was recorded. Each dog's rectal body temperature and body condition scores also were determined.

RESULTS

The skin pH in dogs <12 weeks of age was significantly lower (3.97-5.70) than in older dogs (4.40-8.18) (P < 0.001). In dogs >12 weeks of age, skin pH was significantly lower in the inguinal regions compared to the pinnae (P = 0.008), and female dogs had a significantly lower skin pH in the inguinal regions than male dogs (P = 0.043). Pinnae covered with light-coloured hair had a lower skin pH than those with dark-coloured hair (P = 0.04). No significant differences were found between dogs with different body condition scores, body temperatures or differences in hair density.

CONCLUSIONS AND CLINICAL RELEVANCE

The pH of intact healthy skin is lower in puppies of <12 weeks of age. Regional differences of body location also were seen which were variably affected by hair colour and sex. A baseline assessment of skin pH in healthy dogs is important for future studies of disease and wound healing.

Towards Optimal pH of the Skin and Topical Formulations: From the Current State of the Art to Tailored Products

Acidic pH of the skin surface has been recognized as a regulating factor for the maintenance of the stratum corneum homeostasis and barrier permeability. The most important functions of acidic pH seem to be related to the keratinocyte differentiation process, the formation and function of epidermal lipids and the corneocyte lipid envelope, the maintenance of the skin microbiome and, consequently, skin disturbances and diseases. As acknowledged extrinsic factors that affect skin pH, topically applied products could contribute to skin health maintenance via skin pH value control. The obtained knowledge on skins’ pH could be used in the formulation of more effective topical products, which would add to the development of the so-called products ‘for skin health maintenance’. There is a high level of agreement that topical products should be acidified and possess pH in the range of 4 to 6. However, formulators, dermatologists and consumers would benefit from some more precise guidance concerning favorable products pH values and the selection of cosmetic ingredients which could be responsible for acidification, together with a more extensive understanding of the mechanisms underlaying the process of skin acidification by topical products.

The examination of biophysical parameters of the skin in Polish Konik horses

This study aimed to assess the biophysical parameters of the skin in Polish Konik horses (Polish primitive horses). According to the authors, this is the first assessment performed on such a wide scale in this group of animals. The evaluation carried out is innovative both with regards to the breed of the animals and the wide scope of the physicochemical skin assessment. The study group comprised mares, stallions and geldings, and the evaluations concerned transepidermal water loss, corneometry, pH, skin temperature assessment and mexametry. These parameters were assessed in five skin regions: the lips, the right ear, the prosternum, the right side of the neck and the chest. The measurements were taken after spreading the hair apart, with the use of a Multiprobe Adapter System (MPA^®) and dedicated probes (Courage + Khazaka electronic GmbH, Cologne, Germany). The measurements revealed statistically significant differences in the values of transepidermal water loss in the lips in mares compared with stallions (P = 0.023) and also in stallions compared with geldings (P = 0.009). Corneometry showed significantly higher results in the neck region in mares compared with stallions (P = 0.037) and the prosternum areas in mares and geldings compared with stallions (P = 0.037 and P = 0.018). Skin pH measurement on the right side of the neck rendered significantly higher values in stallions than in mares (P = 0.037). In geldings, the skin temperature was significantly higher than in stallions (P = 0.049). Once the appropriate physicochemical values for specific animal species and breeds are determined, non-invasive methods of skin examination in many diseases and also methods of evaluation of the efficacy and/or adverse effects of applied medications can be established.

An assessment of working canine contamination from standing liquid hazards during a simulated disaster search scenario

Working canines have the potential to be exposed to hazardous materials during search and rescue deployments. Unfortunately, little data are available regarding likely areas of contamination on working canines or effective techniques for substance removal. We describe recent work using an oil-based UV fluorescent marker pooled to mimic standing liquid hazards in a simulated disaster scene to characterize anatomical locations likely to be contaminated. This study utilized three simulated "contaminated" environments situated across a disaster training complex. Federal Emergency Management Agency (FEMA) working canines (n = 11) searched the simulated disaster scene and traversed each contaminated environment. Following the search, all canines were kenneled for 30 minutes and then photographed to capture anatomic locations of exposure. The canines were then taken immediately to the decontamination station where handlers' attempts at canine decontamination were recorded. Anatomical locations were coded as ventral or dorsal, and then further subdivided to the neck, chest, lower legs, and paws for ventral exposures; and back, head, face, and hips for dorsal exposures. Contamination occurred consistently on the paws and lower legs with overall ventral exposure occurring in 39 of 44 (89%) observations. Contamination of the back and head was infrequent, with overall dorsal exposure occurring in 11 of 44 (25%) observations. Despite handler awareness of the exact anatomical locations of exposure with a greater frequency of exposure involving ventral (78%) versus dorsal (22%) regions of the canine (P < 0.0001), time spent decontaminating the two regions did not differ (P = 0.881). These data indicate a need for additional research to identify effective decontamination techniques. Furthermore, the results suggest that additional training may be needed to educate handlers and veterinary personnel regarding anatomic locations on working canines likely to be contaminated during disaster operations in environments where standing liquid hazards are present.

Preclinical studies indicate that INFLATIV, an herbal medicine cream containing Pereskia aculeata, presents potential to be marketed as a topical anti-inflammatory agent and as adjuvant in psoriasis therapy

OBJECTIVES

A previous study reported that the hexane fraction (HF) obtained from Pereskia aculeata leaves showed promising topical anti-inflammatory activity. Intending its future use in clinical practice, a herbal medicine cream named INFLATIV was developed. Its anti-inflammatory and antipsoriatic potential were investigated. INFLATIV was subjected to preliminary accelerated stability tests and to a degradation profile assessment.

METHODS

INFLATIV was prepared at 6% and 12%. The anti-inflammatory activity was assessed by croton oil single and multiple application challenge in mice. Mouse tail test was used for antipsoriatic potential investigation. Cutaneous atrophy test was performed. Preliminary accelerated stability tests were performed together with a degradation profile by GC-MS analysis.

KEY FINDINGS

The anti-inflammatory activity shown by INFLATIV was comparable to dexamethasone. However, the skin atrophy caused by that drug was not observed. INFLATIV modified skin parakeratotic differentiation into orthokeratosis, which revealed its antipsoriatic potential. The ingredients used were suitable to carry the bioactives as they were well permeated by the skin. The preliminary accelerated stability tests indicated that INFLATIV 6% is more stable than 12%.

CONCLUSIONS

The results demonstrated the relevant therapeutic and marketing potentials of INFLATIV, which is likely to be further evaluated in clinical trials for drug registration process with regulatory agencies.

Tailoring the Meso-Structure of Gold Nanoparticles in Keratin-Based Activated Carbon Toward High-Performance Flexible Sensor

Flexible biosensors with high accuracy and reliable operation in detecting pH and uric acid levels in body fluids are fabricated using well-engineered metal-doped porous carbon as electrode material. The gold nanoparticles@N-doped carbon in situ are prepared using wool keratin as both a novel carbon precursor and a stabilizer. The conducting electrode material is fabricated at 500 °C under customized parameters, which mimics A-B type (two different repeating units) polymeric material and displays excellent deprotonation performance (pH sensitivity). The obtained pH sensor exhibits high pH sensitivity of 57 mV/pH unit and insignificant relative standard deviation of 0.088%. Conversely, the composite carbon material with sp² structure prepared at 700 °C is doped with nitrogen and gold nanoparticles, which exhibits good conductivity and electrocatalytic activity for uric acid oxidation. The uric acid sensor has linear response over a range of 1-150 µM and a limit of detection 0.1 µM. These results will provide new avenues where biological material will be the best start, which can be useful to target contradictory applications through molecular engineering at mesoscale.

Role of pH Value in Clinically Relevant Diagnosis

As a highly influential physiological factor, pH may be leveraged as a tool to diagnose physiological state. It may be especially suitable for diagnosing and assessing skin structure and wound status. Multiple innovative and elegant smart wound dressings combined with either pH sensors or drug control-released carriers have been extensively studied. Increasing our understanding of the role of pH value in clinically relevant diagnostics should assist clinicians and improve personal health management in the home. In this review, we summarized a number of articles and discussed the role of pH on the skin surface as well as the factors that influence skin pH and pH-relevant skin diseases, but also the relationship of skin pH to the wound healing process, including its influence on the activity of proteases, bacterial enterotoxin, and some antibacterial agents. A great number of papers discussing physiological pH value have been published in recent decades, far too many to be included in this review. Here, we have focused on the impact of pH on wounds and skin with an emphasis on clinically relevant diagnosis toward effective treatment. We have also summarized the differences in skin structure and wound care between adults and infants, noting that infants have fragile skin and poor skin barriers, which makes them more vulnerable to skin damage and compels particular care, especially for wounds.

A microtiter plate-based quantitative method to monitor the growth rate of dermatophytes and test antifungal activity

Dermatophytosis is one of the most common superficial fungal infections, which is mainly caused by filamentous fungi such as Trichophyton species. A challenging aspect in dermatophyte research is the lack of a straightforward method to measure the rate of growth, in particular when growing dermatophytes in small volumes such as in microtitre plates. However, one characteristic of dermatophytes is their ability to produce compounds such as ammonia that make the growth medium more alkaline. The objective of this study was to test whether the change in pH in a liquid medium, colourimetrically established using the indicator phenol red, was linearly and directly proportional to the growth rate for Trichophyton rubrum and Trichophyton interdigitale. The changes in the colour determined by the phenol-red based assay showed a good correlation with the amount of fungal biomass over an incubation period of 24-120 h. The functionality of the phenol red assay was also validated in experiments on the growth of T. rubrum in the presence of antifungals. The changes in colour showed a clear dose-response relationship compounds and enabled determination of the minimum inhibitory concentration. The phenol red assay is thus a simple and straightforward assay to monitor the rate of growth of Trichophyton spp. and test antifungal activity.

Characterization of PdCP1, a serine carboxypeptidase from Pseudogymnoascus destructans, the causal agent of White-nose Syndrome

Pseudogymnoascus destructans is a pathogenic fungus responsible for White-nose Syndrome (WNS), a disease afflicting multiple species of North American bats. Pseudogymnoascus destructans infects susceptible bats during hibernation, invading dermal tissue and causing extensive tissue damage. In contrast, other Pseudogymnoascus species are non-pathogenic and cross-species comparisons may therefore reveal factors that contribute to virulence. In this study, we compared the secretome of P. destructans with that from several closely related Pseudogymnoascus species. A diverse set of hydrolytic enzymes were identified, including a putative serine peptidase, PdCP1, that was unique to the P. destructans secretome. A recombinant form of PdCP1 was purified and substrate preference determined using a multiplexed-substrate profiling method based on enzymatic degradation of a synthetic peptide library and analysis by mass spectrometry. Most peptide substrates were sequentially truncated from the carboxyl-terminus revealing that this enzyme is a bona fide carboxypeptidase. Peptides with arginine located close to the carboxyl-terminus were rapidly cleaved, and a fluorescent substrate containing arginine was therefore used to characterize PdCP1 activity and to screen a selection of peptidase inhibitors. Antipain and leupeptin were found to be the most potent inhibitors of PdCP1 activity.

Pilot study using five methods to evaluate skin barrier function in healthy dogs and in dogs with atopic dermatitis

BACKGROUND

Atopic dermatitis is associated with skin barrier defects. In people, noninvasive techniques are used to quantify the skin barrier functionality. In dogs, transepidermal water loss (TEWL), stratum corneum hydration and pH have been used to assess skin barrier function. However, few studies have determined their repeatability.

OBJECTIVE

To assess the repeatability of measurements of skin hydration, TEWL, pH, skin absorbance and erythema in healthy and atopic dogs.

ANIMALS

Fifteen healthy and 15 atopic privately owned dogs.

METHODS AND MATERIALS

Three repeated measurements using Corneometer®, Skin-pH-Meter®, Colorimeter® and VapoMeter® were obtained from inguinal, axilla, pinna and interdigital space by three investigators. Intra- and interobserver variability (coefficient of variation, correlation coefficients and intraclass correlation coefficients) and difference between the two groups (t-test or Mann-Whitney U-test) were determined.

RESULTS

High repeatability and low variation were observed both intra- and interobservers for all devices except the VapoMeter®. The most repeatable device was the Skin-pH-Meter®, whereas the VapoMeter® was the device with the highest intra- and interobserver variability. Atopic dogs had a significantly increased pH (inguinal P = 0.03; axilla P = 0.02) and erythema (inguinal P = 0.01; axilla P = 0.02) compared to healthy dogs. No differences between the two groups were detected using the Corneometer®, VapoMeter® or Colorimeter® (tartrazine absorption).

CONCLUSION AND CLINICAL SIGNIFICANCE

The results of this pilot study support the use of Corneometer®, Skin-pH-Meter® and Colorimeter® in the assessment of skin barrier function in dogs; further investigations to optimize measurements and confirm these results are needed.

Wearable Bioelectronics: Enzyme-Based Body-Worn Electronic Devices

In this Account, we detail recent progress in wearable bioelectronic devices and discuss the future challenges and prospects of on-body noninvasive bioelectronic systems. Bioelectronics is a fast-growing interdisciplinary research field that involves interfacing biomaterials with electronics, covering an array of biodevices, encompassing biofuel cells, biosensors, ingestibles, and implantables. In particular, enzyme-based bioelectronics, built on diverse biocatalytic reactions, offers distinct advantages and represents a centerpiece of wearable biodevices. Such wearable bioelectronic devices predominately rely on oxidoreductase enzymes and have already demonstrated considerable promise for on-body applications ranging from highly selective noninvasive biomarker monitoring to epidermal energy harvesting. These systems can thus greatly increase the analytical capability of wearable devices from the ubiquitous monitoring of mobility and vital signs, toward the noninvasive analysis of important chemical biomarkers. Wearable enzyme electrodes offer exciting opportunities to a variety of areas, spanning from healthcare, sport, to the environment or defense. These include real-time noninvasive detection of biomarkers in biofluids (such as sweat, saliva, interstitial fluid and tears), and the monitoring of environmental pollutants and security threats in the immediate surrounding of the wearer. Furthermore, the interface of enzymes with conducting flexible electrode materials can be exploited for developing biofuel cells, which rely on the bioelectrocatalytic oxidation of biological fuels, such as lactate or glucose, for energy harvesting applications. Crucial for such successful application of enzymatic bioelectronics is deep knowledge of enzyme electron-transfer kinetics, enzyme stability, and enzyme immobilization strategies. Such understanding is critical for establishing efficient electrical contacting between the redox enzymes and the conducting electrode supports, which is of fundamental interest for the development of robust and efficient bioelectronic platforms. Furthermore, stretchable and flexible bioelectronic platforms, with mechanical properties similar to those of biological tissues, are essential for handling the rigors of on-body operation. As such, special attention must be given to changes in the behavior of enzymes due to the uncontrolled conditions of on-body operation (including diverse outdoor activities and different biofluids), for maintaining the attractive performance that these bioelectronics devices display in controlled laboratory settings. Therefore, a focus of this Account is on interfacing biocatalytic layers onto wearable electronic devices for creating efficient and stable on-body electrochemical biosensors and biofuel cells. With proper attention to key challenges and by leveraging the advantages of biocatalysis, electrochemistry, and flexible electronics, wearable bioelectronic devices could have a tremendous impact on diverse biomedical, fitness, and defense fields.

Fluorescence-Based Detection of Natural Transformation in Drug-Resistant Acinetobacter baumannii

Acinetobacter baumannii is a nosocomial agent with a high propensity for developing resistance to antibiotics. This ability relies on horizontal gene transfer mechanisms occurring in the Acinetobacter genus, including natural transformation. To study natural transformation in bacteria, the most prevalent method uses selection for the acquisition of an antibiotic resistance marker in a target chromosomal locus by the recipient cell. Most clinical isolates of A. baumannii are resistant to multiple antibiotics, limiting the use of such selection-based methods. Here, we report the development of a phenotypic and selection-free method based on flow cytometry to detect transformation events in multidrug-resistant (MDR) clinical A. baumannii isolates. To this end, we engineered a translational fusion between the abundant and conserved A. baumannii nucleoprotein (HU) and the superfolder green fluorescent protein (sfGFP). The new method was benchmarked against the conventional antibiotic selection-based method. Using this new method, we investigated several parameters affecting transformation efficiencies and identified conditions of transformability one hundred times higher than those previously reported. Using optimized transformation conditions, we probed natural transformation in a set of MDR clinical and nonclinical animal A. baumannii isolates. Regardless of their origin, the majority of the isolates displayed natural transformability, indicative of a conserved trait in the species. Overall, this new method and optimized protocol will greatly facilitate the study of natural transformation in the opportunistic pathogen A. baumannii IMPORTANCE Antibiotic resistance is a pressing global health concern with the rise of multiple and panresistant pathogens. The rapid and unfailing resistance to multiple antibiotics of the nosocomial agent Acinetobacter baumannii, notably to carbapenems, prompt to understand the mechanisms behind acquisition of new antibiotic resistance genes. Natural transformation, one of the horizontal gene transfer mechanisms in bacteria, was only recently described in A. baumannii and could explain its ability to acquire resistance genes. We developed a reliable method to probe and study natural transformation mechanism in A. baumannii More broadly, this new method based on flow cytometry will allow experimental detection and quantification of horizontal gene transfer events in multidrug-resistant A. baumannii.

Does Flooring Substrate Impact Kennel and Dog Cleanliness in Commercial Breeding Facilities?

Evaluation of kennel flooring surfaces is needed to understand their impacts on dog health and well-being. This pilot study aimed to characterize aspects of physical health, kennel cleanliness, and dog body cleanliness on flooring types common in US breeding kennels. Subjects were 118 adult dogs housed on diamond-coated expanded metal (DCEM), polypropylene (POLY), or concrete (CON) flooring at five commercial breeding facilities in Indiana, U.S. Body condition, paw, elbow, and hock health scores were recorded. Each indoor kennel and dog was visually assessed for cleanliness. Kennels were swabbed immediately after cleaning with electrostatic dry cloths and cultured for Escherichia coli. Descriptive statistics were used for analysis. Mean body condition score (BCS), kennel and dog cleanliness scores were all near ideal (3, 1.15, and 1.04, respectively). Thirty-one percent or fewer kennels at each facility were culture-positive for E. coli after cleaning. No serious paw, elbow, or hock problems were identified. Overall, the findings indicate that with appropriate management and regular access to additional surfaces, dog foot health, cleanliness, and kennel cleanliness can be maintained on the flooring types investigated.

Specific dermatological benefits associated with quantities of lotion transferred to the skin

BACKGROUND

A growing number of manufacturers are taking advantage of the ability of absorbent consumer products to deliver lotion to the skin. The lotion is included on these products to help protect the skin from adverse skin effects that can occur, including: (1) irritation, (2) over hydration of the stratum corneum, (3) dryness that can occur from extended exposure to highly absorbent consumer products, and (4) changes in pH.

OBJECTIVE

This manuscript presents results of a quantitative lotion transfer study of adult incontinence products. Resulting lotion transfer is compared to the results of several separate experiments in which specific skin benefits have been correlated to lotion concentrations.

METHODS

The behind-the-knee (BTK) lotion transfer protocol was used to quantitate lotion transfer from adult incontinence (AI) test products constructed using 2 lotion formulations and 2 configurations of lotion application. A modified arm patch protocol, in which skin sites of a measured dimension were pre-treated with specific volumes of lotion, was used to evaluate protective effects of lotion against exposure to irritants, and over hydration from wetted absorbent products.

RESULTS

After a 6-hours continuous exposure in the BTK the 5-stripe lotion configuration products transferred (adjusted mean ± SE) 94 ± 11-104 ± 11 μg/cm² lotion. After 24 hours of wear, transfer had increased to 127 ± 22 and 149 ± 24 μg/cm² , respectively. The single-block configuration products transferred 289 ± 10-316 ± 10 μg/cm² (P = .04). Transfer after 24 hours of wear was 328 ± 23 and 472 ± 21 μg/cm² , respectively (P < .0001). Several protocols were used to evaluate the concentration of lotion required to provide four specific skin benefits. In studies evaluating protection against irritants, skin site pre-treated with lotion were patched with 0.5% sodium lauryl sulfate (SLS). Protective effects were assessed by visual assessment of erythema and trans-epidermal water loss (TEWL). In the first experiment, lotion pre-treatment concentrations as low as 165 μg/cm² exhibited significantly (P < .05) lower erythema and TEWL compared to the positive irritant control (ie, no lotion pre-treatment and SLS only). In the second experiment, lotion pre-treatment concentrations of 80 μg/cm² (P = .018) exhibited significantly (P = .018) lower TEWL. In two studies on protection from over hydration, lotion pre-treatment sites were subsequently patched with wetted absorbent consumer products. The change in TEWL was used as a measure of over hydration. Lotion concentrations significantly reduced the increase in TEWL at 80 μg/cm² (P = .007) and 70 μg/cm² (P ≤ .05). A BTK study was used to evaluate the ability of lotion to prevent dryness. After 6 hours of wear, test products transferring lotion concentrations of 110 or 133 μg/cm² produced significantly lower scores for dryness compared to products transferring 48 or 69 μg/cm² . Using collagen sheets to mimic the stratum corneum, an in vitro study was conducted to measure the ability of lotion to prevent passage of high pH buffer solution. Results demonstrated that the lowest concentration of lotion that was tested (110 μg/cm² ) interfered with passage of the high pH buffer through the collagen sheet, delaying the rise in pH.

CONCLUSIONS

We can conclude that pretreatment with 110 μg/cm² lotion acts as a barrier to high pH fluids such as urine. Using the measurement of lotion transfer from the AI products, together with the results of studies conducted to determine the concentration of lotion required to provide specific skin benefits, we conclude that the five-stripe lotion configuration AI test products transferred enough lotion (ie, ≥80 μg/cm² ) to provide skin protection with regard to: (1) irritant effects and (2) excess moisture. The single-block AI test products also transferred enough lotion to provide these skin benefits (ie, ≥165 μg/cm² ), and the additional benefits of skin protection against: (3) dryness, and (4) changes in pH.

Skin Health Connected to the Use of Absorbent Hygiene Products: A Review

Over the past 50 years, absorbent hygiene products such as baby diapers and incontinence products have become essential features of modern day life. Through innovation and enhanced technology, their design, composition and performance have been dramatically upgraded from their early forms, and they have transformed the lives of millions of people, improving their quality of life. Skin health related to the use of absorbent hygiene products has accordingly also greatly improved. Still, the wearing of absorbent hygiene products will affect the skin, and for some users the changes in microclimate, mechanical interactions and the exposure to urine and faeces may result in irritant contact dermatitis, i.e. diaper dermatitis (DD) or incontinence-associated dermatitis (IAD). Babies with developing skin and the elderly with deteriorating skin functions who are the most frequent users of absorbent hygiene products are more vulnerable to the causal factors. Although irritant reactions are the most common, allergic contact dermatitis should be considered if a DD/IAD fails to improve by recommended actions. There is also a connection between IAD and pressure ulcer development of which it is important to be aware. A holistic approach of using high-quality absorbent hygiene products in combination with appropriate skin care will help maintaining good skin health.

The in vitro antibacterial activity of incomplete iron salt of polyacrylic acid against Pseudomonas aeruginosa, meticillin-resistant Staphylococcus pseudintermedius and meticillin-resistant S. aureus

BACKGROUND

The incomplete iron salt of polyacrylic acid (IIS-PAA) has been used for its haemostatic, wound healing and antibacterial properties in human patients. IIS-PAA is a water-soluble, acidic, hydrophilic polymer that is active at pH 2.9-4.0.

HYPOTHESES/OBJECTIVES

To evaluate the antibacterial effect of IIS-PAA against Pseudomonas aeruginosa, meticillin-resistant Staphylococcus pseudintermedius (MRSP) and meticillin-resistant S. aureus (MRSA).

METHODS

This was a prospective, nonblinded in vitro study. Sixty canine isolates of P. aeruginosa, MRSP and MRSA were included. Minimum inhibitory concentrations (MICs) of IIS-PAA were determined by agar dilution on Mueller-Hinton agar using testing concentrations ranging from 0.0625-0.4% (raw material 100%) and based on Clinical and Laboratory Standards Institute guidelines.

RESULTS

The median MIC for P. aeruginosa was 0.2% (range 0.2-0.3%), mean 0.2% and standard deviation (SD) of 0.018%. The median MIC for MRSP was 0.05% (0.025-0.1%), mean 0.058% and SD 0.022%, and the median MIC for MRSA was 0.1% (0.00625-0.4%), mean 0.126% and SD 0.080%. There were significant differences in MICs between the three bacteria types with MICs highest for Pseudomonas and lowest for MRSP (all P < 0.0001).

CONCLUSIONS

IIS-PAA had in vitro antibacterial activity against three important bacterial pathogens. Further studies of IIS-PAA are indicated to assess the potential clinical benefit and in vitro studies to investigate the spectrum of anti-bacterial activity and mode of action.

Influence of horse breed on transepidermal water loss

Non-invasive methods of skin condition assessment include, among others, the evaluation of transepidermal water loss (TEWL). The aim of the study was to examine whether TEWL values depend on horse breed. The study was conducted on four breeds: "Felin" ponies (FP) (n=16), Polish koniks (PK) (n=15), Polish cold-blooded horses (PcbH) (n=11) and Wielkopolska horses (WH) (n=12). It was found that horse breed influences TEWL values. In the neck region, statistically significant differences were found between PK and FP (p=0.006), and PK and WH (p=0.0005). In the lumbar region, there were statistically significant differences between FP and PK (p=0.0009), FP and PcbH (p=0.0016) as well as between PK and WH (p=0.000037), and PcbH and WH (p=0.0006). In the inguinal region statistically significant differences were found between FP and PK (p=0.0003), FP and PcbH (p=0.0005), PK and WH (p=0.009) and PcbH and WH (p=0.006). In the lip region statistically significant differences were observed between FP and PK (p=0.013) as well as between PK and PcbH (p=0.029) and PK and WH (p=0.009). In the examination of TEWL animal breed should be taken into consideration. The non-significant differences found in three of the examined body regions may suggest that these regions are the most adequate for TEWL assessment.

A Cationic Amphiphilic Random Copolymer with pH-Responsive Activity against Methicillin-Resistant Staphylococcus aureus

In this report, we demonstrate the pH-dependent, in vitro antimicrobial activity of a cationic, amphiphilic random copolymer against clinical isolates of drug-resistant Staphylococcus aureus. The polymer was developed toward a long-term goal of potential utility in the treatment of skin infections. The proposed mechanism of action of the polymer is through selectively binding to bacterial membranes and subsequent disruption of the membrane structure/integrity, ultimately resulting in bacterial cell death. The polymer showed bactericidal activity against clinical isolates of methicillin-resistant or vancomycin-intermediate S. aureus. The polymer was effective in killing S. aureus at neutral pH, but inactive under acidic conditions (pH 5.5). The polymer did not exhibit any significant hemolytic activity against human red blood cells or display cytotoxicity to human dermal fibroblasts over a range of pH values (5.5–7.4). These results indicate that the polymer activity was selective against bacteria over human cells. Using this polymer, we propose a new potential strategy for treatment of skin infections using the pH-sensitive antimicrobial polymer agent that would selectively target infections at pH-neutral wound sites, but not the acidic, healthy skin.

Covalently-controlled drug delivery via therapeutic methacrylic tissue adhesives

Therapeutic methacrylic (TMA) monomers lend local, covalently-controlled release of therapeutics, tunable mechanical properties, and increased cytocompatibility to cyanoacrylate medical adhesives.

A Wearable Electrochemical Platform for Noninvasive Simultaneous Monitoring of Ca(2+) and pH

Homeostasis of ionized calcium in biofluids is critical for human biological functions and organ systems. Measurement of ionized calcium for clinical applications is not easily accessible due to its strict procedures and dependence on pH. pH balance in body fluids greatly affects metabolic reactions and biological transport systems. Here, we demonstrate a wearable electrochemical device for continuous monitoring of ionized calcium and pH of body fluids using a disposable and flexible array of Ca(2+) and pH sensors that interfaces with a flexible printed circuit board. This platform enables real-time quantitative analysis of these sensing elements in body fluids such as sweat, urine, and tears. Accuracy of Ca(2+) concentration and pH measured by the wearable sensors is validated through inductively coupled plasma-mass spectrometry technique and a commercial pH meter, respectively. Our results show that the wearable sensors have high repeatability and selectivity to the target ions. Real-time on-body assessment of sweat is also performed, and our results indicate that calcium concentration increases with decreasing pH. This platform can be used in noninvasive continuous analysis of ionized calcium and pH in body fluids for disease diagnosis such as primary hyperparathyroidism and kidney stones.

Longitudinal Evaluation of the Skin Microbiome and Association with Microenvironment and Treatment in Canine Atopic Dermatitis

Host-microbe interactions may play a fundamental role in the pathogenesis of atopic dermatitis, a chronic relapsing inflammatory skin disorder characterized by universal colonization with Staphylococcus species. To examine the relationship between epidermal barrier function and the cutaneous microbiota in atopic dermatitis, this study used a spontaneous model of canine atopic dermatitis. In a cohort of 14 dogs with canine atopic dermatitis, the skin microbiota were longitudinally evaluated with parallel assessment of skin barrier function at disease flare, during antimicrobial therapy, and post-therapy. Sequencing of the bacterial 16S ribosomal RNA gene showed decreased bacterial diversity and increased proportions of Staphylococcus (S. pseudintermedius in particular) and Corynebacterium species compared with a cohort of healthy control dogs (n = 16). Treatment restored bacterial diversity with decreased proportions of Staphylococcus species, concurrent with decreased canine atopic dermatitis severity. Skin barrier function, as measured by corneometry, pH, and transepidermal water loss also normalized with treatment. Bacterial diversity correlated with transepidermal water loss and pH level but not with corneometry results. These findings provide insights into the relationship between the cutaneous microbiome and skin barrier function in atopic dermatitis, show the impact of antimicrobial therapy on the skin microbiome, and highlight the utility of canine atopic dermatitis as a spontaneous nonrodent model of atopic dermatitis.

What is living on your dog's skin? Characterization of the canine cutaneous mycobiota and fungal dysbiosis in canine allergic dermatitis

To characterize the skin-associated fungal microbiota (mycobiota) in dogs, and to evaluate the influence of body site, individual dog or health status on the distribution of fungi, next-generation sequencing was performed targeting the internal transcribed spacer region. A total of 10 dogs with no history of skin disease were sampled at 10 distinct body sites consisting of haired and mucosal skin, and 8 dogs with diagnosed skin allergies were sampled at six body sites commonly affected by allergic disease. Analysis of similarities revealed that body site was not an influencing factor on membership or structure of fungal communities in healthy skin; however, the mucosal sites were significantly reduced in fungal richness. The mycobiota from body sites in healthy dogs tended to be similar within a dog, which was visualized in principle coordinates analysis (PCoA) by clustering of all sites from one dog separate from other dogs. The mycobiota of allergic skin was significantly less rich than that of healthy skin, and all sites sampled clustered by health status in PCoA. Interestingly, the most abundant fungi present on canine skin, across all body sites and health statuses, were Alternaria and Cladosporium—two of the most common fungal allergens in human environmental allergies.

The skin-associated fungal microbiota were characterized in healthy dogs and those with skin allergies using next-generation sequencing, and the authors identified significant influences of the dog and health status on the distribution and diversity of fungal communities.

Variation in bacterial ATP concentration during rapid changes in extracellular pH and implications for the activity of attached bacteria

In this study we investigated the relationship between a rapid change in extracellular pH and the alteration of bacterial ATP concentration. This relationship is a key component of a hypothesis indicating that bacterial bioenergetics - the creation of ATP from ADP via a proton gradient across the cytoplasmic membrane - can be altered by the physiochemical charge-regulation effect, which results in a pH shift at the bacteria's surface upon adhesion to another surface. The bacterial ATP concentration was measured during a rapid change in extracellular pH from a baseline pH of 7.2 to pH values between 3.5 and 10.5. Experiments were conducted with four neutrophilic bacterial strains, including the Gram-negative Escherichia coli and Pseudomonas putida and the Gram-positive Bacillus subtilis and Staphylococcus epidermidis. A change in bulk pH produced an immediate response in bacterial ATP, demonstrating a direct link between changes in extracellular pH and cellular bioenergetics. In general, the shifts in ATP were similar across the four bacterial strains, with results following an exponential relationship between the extracellular pH and cellular ATP concentration. One exception occurred with S. epidermidis, where there was no variation in cellular ATP at acidic pH values, and this finding is consistent with this species' ability to thrive under acidic conditions. These results provide insight into obtaining a desired bioenergetic response in bacteria through (i) the application of chemical treatments to vary the local pH and (ii) the selection and design of surfaces resulting in local pH modification of attached bacteria via the charge-regulation effect.

Physicochemical properties of pH-sensitive hydrogels based on hydroxyethyl cellulose-hyaluronic acid and for applications as transdermal delivery systems for skin lesions

We investigated the physicochemical properties of pH-sensitive hydroxyethyl cellulose (HEC)/hyaluronic acid (HA) complex hydrogels containing isoliquiritigenin (ILTG), and discussed potential applications as transdermal delivery systems for the treatment of skin lesions caused by pH imbalance. HA has skin compatibility and pH functional groups and HEC serves as scaffold to build hydrogels with varied HCE:HA mass ratio. Hydrogels were synthesized via chemical cross-linking, and three-dimensional network structures were characterized via scanning electron microscopy (SEM). The swelling properties and polymer ratios of the hydrogels were investigated at pH values in the range 1-13. HECHA13 (i.e., an HEC:HA mass ratio of 1:3) was found to have optimal rheological and adhesive properties, and was used to investigate the drug release efficiency as a function of pH; the efficiency was greater than 70% at pH 7. Antimicrobial activity assays against Propionibacterium acnes were conducted to take advantage of the pH-sensitive properties of HECHA13. At pH 7, we found that HECHA13, which contained ILTG, inhibited the growth of P. acnes. Furthermore, HECHA13 was found to exhibit excellent permeability into the skin, which penetrated mostly via the hair follicle. These results indicate that this pH-sensitive hydrogel is effective as a transdermal delivery system for antimicrobial therapeutics, with potential applications in the treatment of acne.

Hydrogen-bonded organic semiconductor micro- and nanocrystals: from colloidal syntheses to (opto-)electronic devices

Organic pigments such as indigos, quinacridones, and phthalocyanines are widely produced industrially as colorants for everyday products as various as cosmetics and printing inks. Herein we introduce a general procedure to transform commercially available insoluble microcrystalline pigment powders into colloidal solutions of variously sized and shaped semiconductor micro- and nanocrystals. The synthesis is based on the transformation of the pigments into soluble dyes by introducing transient protecting groups on the secondary amine moieties, followed by controlled deprotection in solution. Three deprotection methods are demonstrated: thermal cleavage, acid-catalyzed deprotection, and amine-induced deprotection. During these processes, ligands are introduced to afford colloidal stability and to provide dedicated surface functionality and for size and shape control. The resulting micro- and nanocrystals exhibit a wide range of optical absorption and photoluminescence over spectral regions from the visible to the near-infrared. Due to excellent colloidal solubility offered by the ligands, the achieved organic nanocrystals are suitable for solution processing of (opto)electronic devices. As examples, phthalocyanine nanowire transistors as well as quinacridone nanocrystal photodetectors, with photoresponsivity values by far outperforming those of vacuum deposited reference samples, are demonstrated. The high responsivity is enabled by photoinduced charge transfer between the nanocrystals and the directly attached electron-accepting vitamin B2 ligands. The semiconducting nanocrystals described here offer a cheap, nontoxic, and environmentally friendly alternative to inorganic nanocrystals as well as a new paradigm for obtaining organic semiconductor materials from commercial colorants.