The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform

David C. Paik - One of the best experts on this subject based on the ideXlab platform.

  • Ex vivo anti-microbial efficacy of various formaldehyde releasers against antibiotic resistant and antibiotic sensitive microorganisms involved in infectious keratitis
    BMC Ophthalmology, 2020
    Co-Authors: Daeryl E. Amponin, Anna Takaoka, Takayuki Nagasaki, Joanna Przybek-skrzypecka, Mariya Zyablitskaya, Leejee H. Suh, Stephen L. Trokel, David C. Paik
    Abstract:

    Background Corneal infections with antibiotic-resistant microorganisms are an increasingly difficult management challenge and chemically or photochemically cross-linking the cornea for therapy presents a unique approach to managing such infections since both direct microbial pathogens killing and matrix stabilization can occur simultaneously. The present study was undertaken in order to compare the anti-microbial efficacy, in vitro, of 5 candidate cross-linking solutions against 5 different microbial pathogens with relevance to infectious keratitis. Methods In vitro bactericidal efficacy studies were carried out using 5 different FARs [Diazolidinyl Urea (DAU), 1,3-bis(hydroxymethyl)-5,5-dimethylimidazolidine-2,4-dione (DMDM), sodium hydroxymethylglycinate (SMG), 2-(hydroxymethyl)-2-nitro-1,3-propanediol (NT = nitrotriol), 2-nitro-1-propanol (NP)] against 5 different microbial pathogens including two antibiotic-resistant species [methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), Pseudomonas aeruginosa (PA), and Candida albicans (CA)]. Standard in vitro antimicrobial testing methods were used. Results The results for MSSA were similar to those for MRSA. DAU, DMDM, and SMG all showed effectiveness with greater effects generally observed with longer incubation times and higher concentrations. Against MRSA, 40 mM SMG at 120 min showed a > 95% kill rate, p   94% kill rate, p  

  • Topical therapeutic corneal and scleral tissue cross-linking solutions: in vitro formaldehyde release studies using cosmetic preservatives.
    Bioscience reports, 2019
    Co-Authors: Anna Takaoka, Kerry Cao, Eric M. Oste, Takayuki Nagasaki, David C. Paik
    Abstract:

    Our recent tissue cross-linking studies using formaldehyde releasers (FARs) suggest that corneal and scleral tissue strengthening may be possible without using ultraviolet irradiation or epithelial removal, two requirements for the photochemical method in widespread clinical use. Thus, the present study was carried out in order to better understand these potential therapeutic solutions by studying the effects of concentration, pH, buffer, time, and tissue reactivity on formaldehyde release of these FARs. Three FARs, sodium hydroxymethyl glycinate (SMG), DMDM, and Diazolidinyl Urea (DAU) were studied using a chromotropic acid colorimetric FA assay. The effects of concentration, pH, and buffer were studied as well as the addition of corneal and scleral tissues. The main determinant of release was found to be dilution factor (concentration) in which maximal release was noted at the lowest concentrations studied (submillimolar). In time dependent studies, after 60 min, FA levels decreased by 38% for SMG, 30% for DMDM, and 19% for DAU with corneal tissue added; and by 40% for SMG, 40% for DMDM, and 15% for DAU with scleral tissue added. We conclude that concentration (dilution factor) was found to be the most important parameter governing the percent of FA released.

  • Cosmetic Preservatives as Therapeutic Corneal and Scleral Tissue Cross-Linking Agents
    Investigative ophthalmology & visual science, 2015
    Co-Authors: Natasha Babar, Anna Takaoka, Kerry Cao, Stephen L. Trokel, Mijung Kim, Yukari Shimizu, Su-young Kim, David C. Paik
    Abstract:

    PURPOSE Previously, aliphatic β-nitroalcohols (BNAs) have been studied as a means to chemically induce tissue cross-linking (TXL) of cornea and sclera. There are a number of related and possibly more potent agents, known as formaldehyde releasers (FARs), that are in commercial use as preservatives in cosmetics and other personal care products. The present study was undertaken in order to screen such compounds for potential clinical utility as therapeutic TXL agents. METHODS A chemical registry of 62 FARs was created from a literature review and included characteristics relevant to TXL such as molecular weight, carcinogenicity/mutagenicity, toxicity, hydrophobicity, and commercial availability. From this registry, five compounds [Diazolidinyl Urea (DAU), imidazolidinyl Urea (IMU), sodium hydroxymethylglycinate (SMG), DMDM hydantoin (DMDM), 5-Ethyl-3,7-dioxa-1-azabicyclo [3.3.0] octane (OCT)] were selected for efficacy screening using two independent systems, an ex vivo rabbit corneal cross-linking simulation setup and incubation of cut scleral tissue pieces. Treatments were conducted at pH 7.4 or 8.5 for 30 minutes. Efficacy was evaluated using thermal denaturation temperature (Tm), and cell toxicity was studied using the trypan blue exclusion method. RESULTS Cross-linking effects in the five selected FARs were pH and concentration dependent. Overall, the Tm shifts were in agreement with both cornea and sclera. By comparison with BNAs previously reported upon, the FARs identified in this study were significantly more potent but with similar or better cytotoxicity. CONCLUSIONS The FARs, a class of compounds well known to the cosmetic industry, may have utility as therapeutic TXL agents. The compounds studied thus far show promise and will be further tested.

Anna Takaoka - One of the best experts on this subject based on the ideXlab platform.

  • Ex vivo anti-microbial efficacy of various formaldehyde releasers against antibiotic resistant and antibiotic sensitive microorganisms involved in infectious keratitis
    BMC Ophthalmology, 2020
    Co-Authors: Daeryl E. Amponin, Anna Takaoka, Takayuki Nagasaki, Joanna Przybek-skrzypecka, Mariya Zyablitskaya, Leejee H. Suh, Stephen L. Trokel, David C. Paik
    Abstract:

    Background Corneal infections with antibiotic-resistant microorganisms are an increasingly difficult management challenge and chemically or photochemically cross-linking the cornea for therapy presents a unique approach to managing such infections since both direct microbial pathogens killing and matrix stabilization can occur simultaneously. The present study was undertaken in order to compare the anti-microbial efficacy, in vitro, of 5 candidate cross-linking solutions against 5 different microbial pathogens with relevance to infectious keratitis. Methods In vitro bactericidal efficacy studies were carried out using 5 different FARs [Diazolidinyl Urea (DAU), 1,3-bis(hydroxymethyl)-5,5-dimethylimidazolidine-2,4-dione (DMDM), sodium hydroxymethylglycinate (SMG), 2-(hydroxymethyl)-2-nitro-1,3-propanediol (NT = nitrotriol), 2-nitro-1-propanol (NP)] against 5 different microbial pathogens including two antibiotic-resistant species [methicillin-sensitive Staphylococcus aureus (MSSA), methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE), Pseudomonas aeruginosa (PA), and Candida albicans (CA)]. Standard in vitro antimicrobial testing methods were used. Results The results for MSSA were similar to those for MRSA. DAU, DMDM, and SMG all showed effectiveness with greater effects generally observed with longer incubation times and higher concentrations. Against MRSA, 40 mM SMG at 120 min showed a > 95% kill rate, p   94% kill rate, p  

  • Topical therapeutic corneal and scleral tissue cross-linking solutions: in vitro formaldehyde release studies using cosmetic preservatives.
    Bioscience reports, 2019
    Co-Authors: Anna Takaoka, Kerry Cao, Eric M. Oste, Takayuki Nagasaki, David C. Paik
    Abstract:

    Our recent tissue cross-linking studies using formaldehyde releasers (FARs) suggest that corneal and scleral tissue strengthening may be possible without using ultraviolet irradiation or epithelial removal, two requirements for the photochemical method in widespread clinical use. Thus, the present study was carried out in order to better understand these potential therapeutic solutions by studying the effects of concentration, pH, buffer, time, and tissue reactivity on formaldehyde release of these FARs. Three FARs, sodium hydroxymethyl glycinate (SMG), DMDM, and Diazolidinyl Urea (DAU) were studied using a chromotropic acid colorimetric FA assay. The effects of concentration, pH, and buffer were studied as well as the addition of corneal and scleral tissues. The main determinant of release was found to be dilution factor (concentration) in which maximal release was noted at the lowest concentrations studied (submillimolar). In time dependent studies, after 60 min, FA levels decreased by 38% for SMG, 30% for DMDM, and 19% for DAU with corneal tissue added; and by 40% for SMG, 40% for DMDM, and 15% for DAU with scleral tissue added. We conclude that concentration (dilution factor) was found to be the most important parameter governing the percent of FA released.

  • Cosmetic Preservatives as Therapeutic Corneal and Scleral Tissue Cross-Linking Agents
    Investigative ophthalmology & visual science, 2015
    Co-Authors: Natasha Babar, Anna Takaoka, Kerry Cao, Stephen L. Trokel, Mijung Kim, Yukari Shimizu, Su-young Kim, David C. Paik
    Abstract:

    PURPOSE Previously, aliphatic β-nitroalcohols (BNAs) have been studied as a means to chemically induce tissue cross-linking (TXL) of cornea and sclera. There are a number of related and possibly more potent agents, known as formaldehyde releasers (FARs), that are in commercial use as preservatives in cosmetics and other personal care products. The present study was undertaken in order to screen such compounds for potential clinical utility as therapeutic TXL agents. METHODS A chemical registry of 62 FARs was created from a literature review and included characteristics relevant to TXL such as molecular weight, carcinogenicity/mutagenicity, toxicity, hydrophobicity, and commercial availability. From this registry, five compounds [Diazolidinyl Urea (DAU), imidazolidinyl Urea (IMU), sodium hydroxymethylglycinate (SMG), DMDM hydantoin (DMDM), 5-Ethyl-3,7-dioxa-1-azabicyclo [3.3.0] octane (OCT)] were selected for efficacy screening using two independent systems, an ex vivo rabbit corneal cross-linking simulation setup and incubation of cut scleral tissue pieces. Treatments were conducted at pH 7.4 or 8.5 for 30 minutes. Efficacy was evaluated using thermal denaturation temperature (Tm), and cell toxicity was studied using the trypan blue exclusion method. RESULTS Cross-linking effects in the five selected FARs were pH and concentration dependent. Overall, the Tm shifts were in agreement with both cornea and sclera. By comparison with BNAs previously reported upon, the FARs identified in this study were significantly more potent but with similar or better cytotoxicity. CONCLUSIONS The FARs, a class of compounds well known to the cosmetic industry, may have utility as therapeutic TXL agents. The compounds studied thus far show promise and will be further tested.

Kerry Cao - One of the best experts on this subject based on the ideXlab platform.

  • Topical therapeutic corneal and scleral tissue cross-linking solutions: in vitro formaldehyde release studies using cosmetic preservatives.
    Bioscience reports, 2019
    Co-Authors: Anna Takaoka, Kerry Cao, Eric M. Oste, Takayuki Nagasaki, David C. Paik
    Abstract:

    Our recent tissue cross-linking studies using formaldehyde releasers (FARs) suggest that corneal and scleral tissue strengthening may be possible without using ultraviolet irradiation or epithelial removal, two requirements for the photochemical method in widespread clinical use. Thus, the present study was carried out in order to better understand these potential therapeutic solutions by studying the effects of concentration, pH, buffer, time, and tissue reactivity on formaldehyde release of these FARs. Three FARs, sodium hydroxymethyl glycinate (SMG), DMDM, and Diazolidinyl Urea (DAU) were studied using a chromotropic acid colorimetric FA assay. The effects of concentration, pH, and buffer were studied as well as the addition of corneal and scleral tissues. The main determinant of release was found to be dilution factor (concentration) in which maximal release was noted at the lowest concentrations studied (submillimolar). In time dependent studies, after 60 min, FA levels decreased by 38% for SMG, 30% for DMDM, and 19% for DAU with corneal tissue added; and by 40% for SMG, 40% for DMDM, and 15% for DAU with scleral tissue added. We conclude that concentration (dilution factor) was found to be the most important parameter governing the percent of FA released.

  • Cosmetic Preservatives as Therapeutic Corneal and Scleral Tissue Cross-Linking Agents
    Investigative ophthalmology & visual science, 2015
    Co-Authors: Natasha Babar, Anna Takaoka, Kerry Cao, Stephen L. Trokel, Mijung Kim, Yukari Shimizu, Su-young Kim, David C. Paik
    Abstract:

    PURPOSE Previously, aliphatic β-nitroalcohols (BNAs) have been studied as a means to chemically induce tissue cross-linking (TXL) of cornea and sclera. There are a number of related and possibly more potent agents, known as formaldehyde releasers (FARs), that are in commercial use as preservatives in cosmetics and other personal care products. The present study was undertaken in order to screen such compounds for potential clinical utility as therapeutic TXL agents. METHODS A chemical registry of 62 FARs was created from a literature review and included characteristics relevant to TXL such as molecular weight, carcinogenicity/mutagenicity, toxicity, hydrophobicity, and commercial availability. From this registry, five compounds [Diazolidinyl Urea (DAU), imidazolidinyl Urea (IMU), sodium hydroxymethylglycinate (SMG), DMDM hydantoin (DMDM), 5-Ethyl-3,7-dioxa-1-azabicyclo [3.3.0] octane (OCT)] were selected for efficacy screening using two independent systems, an ex vivo rabbit corneal cross-linking simulation setup and incubation of cut scleral tissue pieces. Treatments were conducted at pH 7.4 or 8.5 for 30 minutes. Efficacy was evaluated using thermal denaturation temperature (Tm), and cell toxicity was studied using the trypan blue exclusion method. RESULTS Cross-linking effects in the five selected FARs were pH and concentration dependent. Overall, the Tm shifts were in agreement with both cornea and sclera. By comparison with BNAs previously reported upon, the FARs identified in this study were significantly more potent but with similar or better cytotoxicity. CONCLUSIONS The FARs, a class of compounds well known to the cosmetic industry, may have utility as therapeutic TXL agents. The compounds studied thus far show promise and will be further tested.

Torkil Menné - One of the best experts on this subject based on the ideXlab platform.

  • FS04.1 Formaldehyde allergy – clinically relevant threshold reactions
    Contact Dermatitis, 2008
    Co-Authors: Claus Zachariae, Barbara Hall, M. Cottin, Klaus Ejner Andersen, Torkil Menné
    Abstract:

    The objective of the study was to establish eliciting threshold concentrations of Diazolidinyl Urea (Germall II)– derived formaldehyde in formaldehyde and/or in Diazolidinyl Urea – sensitive patients, using a leave-on face cream formulation in a repeated open application test (ROAT) applied to different anatomical regions. 150 patients with known formaldehyde allergy were reviewed for inclusion in the study. 108 patients were contacted and in 65 patients the formaldehyde sensitisation was reconfirmed by a patch test. Four groups of 10 formaldehyde allergic subjects were exposed to 0.05%, 0.15%, 0.3% and 0.6% Diazolidinyl Urea, corresponding to approximately 50, 100, 200 and 400 ppm free formaldehyde, respectively. Additional 10 individuals allergic to the formaldehyde donor – Diazolidinyl Urea itself – were exposed to 0.15% DiazolidinylUrea, corresponding to approximately 100 ppm free formaldehyde and 10 healthy non-allergic individuals were exposed to 0.6% of DiazolidinylUrea (approximately 400 ppm free formaldehyde). A ROAT was performed in a scheduled sequence: upper arm, neck and face. Contact allergy reactions were elicited in 39 out of 58 formaldehyde-sensitive and in 5 out of 7 Diazolidinyl Urea-sensitive individuals. Elicitation responses were dose- and anatomical region – dependent. No reactions were observed at the lowest dose, suggesting that an elicitation threshold was attained in the study.

  • ROAT: morphology of ROAT on arm, neck and face in formaldehyde and Diazolidinyl Urea sensitive individuals.
    Contact dermatitis, 2006
    Co-Authors: Claus Zachariae, Barbara Hall, Sylvie Cupferman, Klaus Ejner Andersen, Torkil Menné
    Abstract:

    The morphology of early allergic contact dermatitis reactions was studied in formaldehyde allergic individuals exposed to a cream product preserved with 4 different concentrations of Diazolidinyl Urea. The study was made using a dose-escalating design in 3 different anatomical regions, the upper arm, neck and face. On the arm and neck, the dominant initial morphology was an eczematous papular eruption. In the face, the initial skin changes were more homogeneous and infiltrated erythema.

  • Experimental elicitation of contact allergy from a Diazolidinyl Urea-preserved cream in relation to anatomical region, exposure time and concentration
    Contact dermatitis, 2005
    Co-Authors: Claus Zachariae, Barbara Hall, M. Cottin, Sylvie Cupferman, Klaus Ejner Andersen, Torkil Menné
    Abstract:

    The elicitation potential of the cosmetic preservative Diazolidinyl Urea was studied in formaldehyde- and Diazolidinyl Urea-sensitized volunteer patients using a stepwise controlled exposure design. The test product was a facial moisturizer, preserved with varying concentrations of Diazolidinyl Urea, ranging from 0.05% to 0.6%. A repeated open application-like exposure test was performed on volunteers and a control group with the test product containing increasing preservative concentrations, on arm, neck and face, sequentially, for 2 weeks or until dermatitis developed. The preservative action in the cream at different test concentrations was tested in microbial challenge tests and was found effective at all concentrations tested. The study established a non-eliciting concentration of Diazolidinyl Urea of 0.05% in formaldehyde-sensitive patients and showed that the skin reactivity depends on the anatomical region, increasing from the upper arm to neck and, possibly, to the face. The study design, beginning on the upper arm and moving on to the neck and face seems to be relevant for the study of reactions to cosmetic products. A clear dose-response relationship was seen regarding preservative concentration in the product.

  • Standardization of the TRUE Test imidazolidinyl Urea and Diazolidinyl Urea patches
    Contact dermatitis, 2001
    Co-Authors: Tove Agner, Klaus Ejner Andersen, Torkil Menné, Ulla Hoeck, Bo Kreilgaard, Bert Björkner, Magnus Bruze, P. J. Frosch, B Gruvberger, J Sommer
    Abstract:

    The preservatives imidazolidinyl Urea (IMID, Germall 115) and Diazolidinyl Urea (DU, Germall II) are commonly used in cosmetic products and are well-known sensitizers. The aim of the present study was to establish the optimal patch test concentration in hydrophilic dried-in vehicle (TRUE Test) for IMID and DU. 181 patients were included in the study. Of these, 150 were patients referred for patch testing, 12 were patients with known allergy to IMID and 19 were patients with known allergy to DU. 76 consecutive patients and the 12 IMID-allergic patients were patch tested with a dilution series IMID (0 to 600 microg/cm(2)), formaldehyde (180 microg/cm(2)) and DU (200 microg/cm(2)). 74 consecutive patients and the 19 DU-allergic patients were patch tested with a dilution series of DU (0 to 600 microg/cm(2)), formaldehyde (180 microg/cm) and IMID (200 microg/cm(2)). A positive dose-response relationship was found. The number of doubtful reactions decreased with increasing test concentrations. No late reactions were observed. A patch test concentration in hydrophilic dried-in vehicle (TRUE Test) of 600 microg/cm(2) was found to be adequate and safe for both IMID and DU.

Eva Nyhammar - One of the best experts on this subject based on the ideXlab platform.

  • A method for quantification of formaldehyde in the presence of formaldehyde donors in skin-care products.
    Contact Dermatitis, 1998
    Co-Authors: Ann-therese Karlberg, Ingrid Lindberg, Lizbet Skare, Eva Nyhammar
    Abstract:

    : Reliable and uncomplicated methods for detection of free formaldehyde in products preserved with formaldehyde donors are desirable to decrease the risk of allergic contact dermatitis. The aim of this study was to develop a method that could be used in clinics and workplaces for quantification of free formaldehyde in products preserved with formaldehyde donors. The method developed is named the closed container diffusion (CCD) method. Formaldehyde in a sample is allowed to evaporate in a closed container and react with 2,4-dinitrophenylhydrazine coated on a glass fibre filter. The hydrazone formed is analyzed with HPLC. The method was tested on 3 different formaldehyde donors, imidazolidinyl Urea, Diazolidinyl Urea and 2-bromo-2-nitropropane-1,3-diol, using 4 different cream bases. The results obtained with this method accord, with those obtained with the official method within the European Union (EU). The method is sensitive enough for analysis of patients' products and for control of labelled amounts of formaldehyde in technical products without solvent extraction. As a result of our studies, we observed a risk of exceeding the labelling limit for free formaldehyde in cosmetic products when using the highest amount of Diazolidinyl Urea allowed within the EU.

  • A method for quantification of formaldehyde in the presence of formaldehyde donors in skin‐care products
    Contact dermatitis, 1998
    Co-Authors: Ann-therese Karlberg, Ingrid Lindberg, Lizbet Skare, Eva Nyhammar
    Abstract:

    Reliable and uncomplicated methods for detection of free formaldehyde in products preserved with formaldehyde donors are desirable to decrease the risk of allergic contact dermatitis. The aim of this study was to develop a method that could be used in clinics and workplaces for quantification of free formaldehyde in products preserved with formaldehyde donors. The method developed is named the closed container diffusion (CCD) method. Formaldehyde in a sample is allowed to evaporate in a closed container and react with 2,4-dinitrophenylhydrazine coated on a glass fibre filter. The hydrazone formed is analyzed with HPLC. The method was tested on 3 different formaldehyde donors, imidazolidinyl Urea, Diazolidinyl Urea and 2-bromo-2-nitropropane-1,3-diol, using 4 different cream bases. The results obtained with this method accord, with those obtained with the official method within the European Union (EU). The method is sensitive enough for analysis of patients' products and for control of labelled amounts of formaldehyde in technical products without solvent extraction. As a result of our studies, we observed a risk of exceeding the labelling limit for free formaldehyde in cosmetic products when using the highest amount of Diazolidinyl Urea allowed within the EU.