Our library of drug research abstracts drawn from the medical literature is updated on a regular schedule, and you can be assured that new retin research articles will be listed here shortly after becoming available to us.
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Medical research on retin
Exp Eye Res. 2008 Jun 7;
Brennan LA, Kantorow M
Oxidative stress occurs when the level of prooxidants exceeds the level of antioxidants in cells resulting in oxidation of cellular components and consequent loss of cellular function. Oxidative stress is implicated in wide range of age-related disorders including Alzheimer's disease, Parkinson's disease amyotrophic lateral sclerosis (ALS), Huntington's disease and the aging process itself [Lin, T.L., Beal, M.F., 2006. Mitochondrial dysfunction and oxidative stress in neurodegenerative diseases. Nature 443, 787-795]. In the anterior segment of the eye, oxidative stress has been linked to lens cataract [Truscott, R.J.W., 2005. Age-related nuclear cataract - oxidation is the key. Exp. Eye Res. 80, 709-725] and glaucoma [Tezel, G., 2006. Oxidative stress in glaucomatous neurodegeneration: mechanisms and consequences. Prog. Retin. Eye Res. 25, 490-513], while in the posterior segment of the eye oxidative stress has been associated with macular degeneration [Hollyfield, J.G., Bonilha, V.L., Rayborn, M.E., Yang, X., Shadrach, K.G., Lu, L., Ufret, R.L., Aalomen, R.G., Perez, V.L. 2008. Oxidative damage-induced inflammation initiates age-related macular degeneration. Nat. Med. 14 (2), 194-198]. Key to many oxidative stress conditions are alterations in the efficiency of mitochondrial respiration resulting in superoxide (O(2)(-)) production. Superoxide production precedes subsequent reactions that form potentially more dangerous reactive oxygen species (ROS) species such as the hydroxyl radical (OH), hydrogen peroxide (H(2)O(2)) and peroxynitrite (OONO(-)). The major source of ROS in the mitochondria, and in the cell overall, is leakage of electrons from complexes I and III of the electron transport chain. It is estimated that 0.2-2% of oxygen taken up by cells is converted to ROS, through mitochondrial superoxide generation, by the mitochondria [Hansford, R.G., Hogue, B.A., Mildazien, V., 1997. Dependence of H(2)O(2) formation by rat heart mitochondria on substrate availability and donor age. J. Bioenerg. Biomembr. 29, 89-95]. Generation of superoxide at complexes I and III has been shown to occur at both the matrix side of the inner mitochondrial membrane and the cytosolic side of the membrane [Kakkar, P., Singh, B.K., 2007. Mitochondria: a hub of redox activities and cellular distress control. Mol. Cell. Biochem. 305, 235-253]. While exogenous sources of ROS such as UV light, visible light, ionizing radiation, chemotherapeutics, and environmental toxins may contribute to the oxidative milieu, mitochondria are perhaps the most significant contribution to ROS production affecting the aging process. In addition to producing ROS, mitochondria are also a target for ROS which in turn reduces mitochondrial efficiency and leads to the generation of more ROS in a vicious self-destructive cycle. Consequently, the mitochondria have evolved a number of antioxidant and key repair systems to limit the damaging potential of free oxygen radicals and to repair damaged proteins (Fig. 1). The aging eye appears to be at considerable risk from oxidative stress. This review will outline the potential role of mitochondrial function and redox balance in age-related eye diseases, and detail how the methionine sulfoxide reductase (Msr) protein repair system and other redox systems play key roles in the function and maintenance of the aging eye.
Active learning methods for interactive image retrieval.
IEEE Trans Image Process. 2008 Jul; 17(7): 1200-11
Gosselin PH, Cord M
Active learning methods have been considered with increased interest in the statistical learning community. Initially developed within a classification framework, a lot of extensions are now being proposed to handle multimedia applications. This paper provides algorithms within a statistical framework to extend active learning for online content-based image retrieval (CBIR). The classification framework is presented with experiments to compare several powerful classification techniques in this information retrieval context. Focusing on interactive methods, active learning strategy is then described. The limitations of this approach for CBIR are emphasized before presenting our new active selection process RETIN. First, as any active method is sensitive to the boundary estimation between classes, the RETIN strategy carries out a boundary correction to make the retrieval process more robust. Second, the criterion of generalization error to optimize the active learning selection is modified to better represent the CBIR objective of database ranking. Third, a batch processing of images is proposed. Our strategy leads to a fast and efficient active learning scheme to retrieve sets of online images (query concept). Experiments on large databases show that the RETIN method performs well in comparison to several other active strategies.
Stratum corneum barrier integrity controls skin homeostasis.
Int J Cosmet Sci. 1999 Apr; 21(2): 99-106
Smith W
The stratum corneum water barrier controls structural and functional properties of both the epidermis and the dermis. Treatments which chronically disrupt the stratum corneum water barrier can induce changes similar to those seen with 'anti-aging' treatments such as (-Hydroxy acids (AHAs) and Retin Atrade mark. Barrier disruption via daily tape stripping increases epidermal and dermal thickness, superficial and integral skin firmness, and improves skin surface texture. Modest or transitory disruption did not produce such effects. Similar results were observed with topical application of AHAs, retinoids or mild irritants after about 4-6 weeks provided such treatments resulted in prolonged elevation in TEWL (trans-epidermal water loss). Treatments that did not chronically elevate TEWL could also produce positive cosmetic effects, but such effects were in general restricted to the skin surface or epidermis. Irritation, which was observed with some treatments, was not solely responsible for the positive effects observed.
A multi-sample design for assessing the comedolytic activity of topical products.
Int J Cosmet Sci. 2004 Oct; 26(5): 239-43
Knaggs H, Santanastasio H, Bowman J, Pagnoni A
Background: Facial comedolytic studies allow testing of a maximum of two products. The upper back provides a larger area with a more uniform distribution of microcomedones for comedolytic studies. Objective: To design a multi-sample method for assessing comedolytic activity of topical products on the back. The effect of season on product discrimination was also explored. Methods: Three cleansing formulations (products B, C and D), a negative water control and 0.025% Retin-A((R)) cream (positive control) were tested. Seven subjects were recruited in summer and nine in fall. Products were applied for 8 weeks, comedolysis was assessed by visually evaluating cyanoacrylate follicular biopsies taken at baseline and post-treatment. Results: In all data sets (summer, fall and combined), sites treated with Retin-A((R)) had a significantly lower number of microcomedones as compared to the negative water control. In addition, cleansers B and D showed a significant reduction from baseline in the fall and combined (summer and fall) data, but not in summer data alone indicating different responses to treatment during the year. Conclusions: The design was sensitive enough to detect differences between cleansing formulations under normal washing conditions. Reduced sensitivity observed during summer suggests hot humid conditions may decrease the comedolytic performance of topical products. Résumé
Eur J Pharm Biopharm. 2007 Sep; 67(2): 387-97
Taepaiboon P, Rungsardthong U, Supaphol P
The present contribution reports the use of mats of electrospun cellulose acetate (CA; acetyl content=39.8%; Mw=30,000 Da) nanofibers as carriers for delivery of the model vitamins, all-trans retinoic acid or vitamin A acid (Retin-A) and alpha-tocopherol or vitamin E (Vit-E). The amounts of Vit-E and Retin-A loaded in the base CA solution [17% w/v in 2:1 v/v acetone/N,N-dimethylacetamide (DMAc)] were 5 and 0.5 wt% (based on the weight of CA), respectively. Cross-sectionally round and smooth fibers were obtained. The average diameters of these fibers ranged between 247 and 265 nm. The total immersion of the vitamin-loaded as-spun CA fiber mats in the acetate buffer solutions containing either 0.5 vol % Tween 80 or 0.5 vol % Tween 80 and 10 vol % methanol was used to arrive at the cumulative release of the vitamins from the fiber mat samples. The same was also conducted on the vitamin-loaded solution-cast CA films for comparison. In most cases, the vitamin-loaded as-spun fiber mats exhibited a gradual and monotonous increase in the cumulative release of the vitamins over the test periods (i.e., 24 h for Vit-E-loaded samples and 6 h for Retin-A-loaded ones), while the corresponding as-cast films exhibited a burst release of the vitamins.
Clinical inquiries. What is the best treatment for mild to moderate acne?
J Fam Pract. 2006 Nov; 55(11): 994-6
Rao S, Malik MA, Wilder L, Mott T
For mild comedonal acne, monotherapy with topical retinoids is the treatment of choice (strength of recommendation [SOR]: A). For moderate comedonal and mild to moderate papulopustular acne, combination therapy with either benzoyl peroxide or topical retinoids (adapalene [Differin], tazarotene [Tazorac], tretinoin [Retin-A]) plus topical antibiotics (erythromycin or clindamycin) is proven most effective (SOR: A). Six to 8 weeks should be allowed for most treatments to work before altering the regimen (SOR: A).
Gynecol Oncol. 2007 Mar; 104(3): 547-50
Black D, Tornos C, Soslow RA, Awtrey CS, Barakat RR, Chi DS
OBJECTIVES: Vulvar Paget's disease is a rare neoplasm that usually occurs in postmenopausal women. Treatment with surgical excision can be complicated by extension of microscopic disease in an irregular manner well beyond the visible margins of the lesion. The objective or our study was to analyze the outcomes of patients with primary vulvar intraepithelial Paget's disease who had positive microscopic margins after primary excision. METHODS: We reviewed the records of all patients with Paget's disease of the vulva treated at our institution from 1/80 to 9/02. Patients whose sample showed stromal invasion or an underlying carcinoma were excluded. Data were collected regarding patient demographics, disease location, treatment, surgical margin status, additional treatment, and clinical outcome. RESULTS: The medical records and histopathologic specimens of 28 women with intraepithelial Paget's disease of the vulva were evaluated. Surgical treatment consisted of radical vulvectomy in 3 patients (11%), simple vulvectomy in 18 patients (64%), and wide local excision in the other 7 patients (25%). Of the 20 patients with microscopically positive margins, 14 (70%) developed recurrent disease and the remaining 6 (30%) are disease free. Of the 8 patients with negative margins, 3 (38%) developed disease recurrence and the remaining 5 (63%) are disease free. With a median follow-up of 49 months (range, 3-186 months), there was no correlation between disease recurrence and margin status (P=0.20). Of the 17 patients who recurred, 14 (82%) underwent additional surgical excision and 1 patient was treated with Retin-A. The remaining 2 patients refused further treatment and were lost to follow-up. In those patients who underwent surgery for recurrence, between 1 and 3 re-excisions were performed. Of the 15 evaluable patients who were treated for recurrent disease, 12 (80%) had no evidence of persistent disease and 3 (20%) had persistent disease at a median follow-up of 63.7 months (range, 18.5-186 months). CONCLUSIONS: Microscopically positive margins following surgical excision of vulvar intraepithelial Paget's disease is a frequent finding, and disease recurrence is common regardless of surgical margin status. Long-term monitoring of patients is recommended, and repeat surgical excision is often necessary.
Schools of pharmacology: retinoid update.
J Drugs Dermatol. 2006 Oct; 5(9): 921-2
Scheinfeld N
The most widely used retinoids include topical tretinoin (Retin-A), adapalene (Differin), topical tazarotene (Tazorac), isotretinoin (Accutane), and acitretin (Soriatane). This article will review new uses and developments in tazarotene (its failure to secure FDA approval in oral form for psoriasis), adapalene (its new 0.3% gel form and use in rosacea), alitretinoin (its use in photoaging), bexarotene (its use for psoriasis and chronic hand dermatitis), isotretinoin (the IPledge program, its use for neuroblastoma and branded formulation pharmacological superiority to generics), and retinoic acid metabolism-blocking agents (RAMBAs) (liarazole use for ichthyosis and psoriasis).
Safety and efficacy of Tretin-X compared with Retin-A in patients with mild-to-severe acne vulgaris.
Skinmed. 2006 May-Jun; 5(3): 114-8
Webster GF
BACKGROUND AND OBJECTIVE: The therapeutic efficacy of the tretinoin products Tretin-X (Triax Pharmaceuticals, Cranford, NJ) and Retin-A (Johnson & Johnson, New Brunswick, NJ) in the treatment of acne vulgaris was compared in four bioequivalence studies. METHODS: Four double-blind, three-treatment, parallel-group studies randomly assigned 1642 adolescents and adults, 12-40 years of age, with mild-to-severe acne vulgaris to receive topical tretinoin therapy with Tretin-X, Retin-A, or placebo (drug vehicle) as 0.1% cream (study 1), 0.025% cream (study 2), 0.025% gel (study 3), and 0.01% gel (study 4) once daily for 84 days. The primary efficacy measures were overall acne severity and the number of inflammatory lesions. The secondary efficacy measure was the total number of lesions. RESULTS: In each trial, Tretin-X and Retin-A were clinically equivalent according to all primary and secondary end points at Weeks 2, 4, 8, and 12, a finding also demonstrated by the averaged scores from Weeks 2 through 12. Moreover, each active treatment was significantly more efficacious than placebo at the conclusion of the study (p
Retin-A may help diabetic foot ulcers heal.
Health News. 2006 Apr; 12(4): 7