RESUMEN

A comprehensive investigation into the effects of nonlinear material behaviour of polymeric (MN) and skin on the dynamics of the MN insertion in skin was undertaken in this study using experiments and numerical simulations. The nonlinearity of the material behaviour was incorporated by employing the Ramberg-Osgood and neo-Hookean equations for stress-strain relationships for the MN materials and skin, respectively. For this purpose, a characteristic type of dissolving MN array was selected. This type of MN is made by a combination of poly(vinyl alcohol) and poly(vinyl pyrrolidone). The numerical simulations were validated using experimental investigations where the MNs were fabricated using laser-engineered silicone micromould templates technology. Young's modulus, Poisson's ratio, and compression breaking force for the MN polymers were determined using a texture analyser. The alignment between experimental findings and simulation data underscores the accuracy of the parameters determined through mechanical testing and mathematical calculations for both MN materials (PVP/PVA) and skin behaviour during the MN insertion. This study has demonstrated a strong alignment between the experimental findings and computational simulations, confirming the accuracy of the established parameters for MNs and skin interactions for modelling MN insertion behaviour in skin, providing a solid foundation for future research in this area.

Asunto(s)

Asunto(s)

RESUMEN

This study aimed to determine whether there was a difference in skin permeability to methylene blue dye or skin morphology between dairy cows that differed in their susceptibility to digital dermatitis (DD) and to assess the effect of contact with slurry on skin permeability. Twenty nine dairy cows were monitored for DD during the winter housing period and classed as DD+ (previous DD infection, n = 17), or DD- (no recorded infection, n = 12). The animals were culled and a skin sample was taken from above the heel of each hind foot and frozen. Samples were later defrosted and one sample from each cow was tested for permeability, whereas the other was treated with slurry for 24 h before permeability testing. To test permeability, methylene blue dye was applied to the skin surface in a Franz diffusion cell. After 48 h, the amount of dye that had passed through the skin was estimated. The stratum corneum thickness and the density of hair follicles were determined from additional heel skin samples. Skin permeability to methylene blue dye was significantly greater for samples that had been treated with slurry but did not differ between DD+ and DD- animals. No difference was found in the stratum corneum thickness or density of hair follicles between DD+ and DD- animals. These findings imply that individual differences in general skin permeability are not a major factor in determining DD susceptibility and suggest that contact with slurry could contribute to DD infection by increasing the permeability of the skin, which may facilitate pathogen entry. Further work is required to clarify the role played by slurry in the pathogenesis of DD.

Asunto(s)

RESUMEN

BACKGROUND: The work in this study appraised photodynamic treatment (PDT) as a treatment method for vulval intraepithelial neoplasia (VIN) using a novel bioadhesive patch to deliver aminolevulinic acid. An analysis of changes in expression of apoptotic and cell cycle proteins (p53, p21, Mdm2, Blc-2, Bax, Ki-67) in response to PDT was evaluated. METHODS: PDT was performed using non-laser light, either as a one or two-cycle treatment, with clinical and pathological assessment following after 6 weeks. Twenty-three patients with 25 VIN lesions underwent 49 cycles of PDT. Patches were designed to conform to uneven vulval skin and contained 38 mg cm(-2) aminolevulinic acid. Assessment was carried out at 6 weeks post-treatment. Patient-based treatment assessment, along with clinical and pathological changes, were monitored. Immunohistochemical staining was used to elucidate a possible biomolecular basis for induced cellular changes. RESULTS: Most patients (52%) reported a symptomatic response, with normal pathology restored in 38% of lesions. The patch was easy to apply and remove, causing minimal discomfort. Fluorescence inspection confirmed protoporphyrin accumulation. Pain during implementation of PDT was problematic, necessitating some form of local analgesia. Changes in expression of cell cycle and apoptotic-related proteins suggested involvement of apoptotic pathways. Down regulation of p21 and inverse changes in Bcl-2 and Bax were key findings. CONCLUSION: Treatment of VIN lesions using a novel bioadhesive patch induced changes in cell cycle and apoptotic proteins in response to PDT with possible utilisation of apoptotic pathways. The efficacy of PDT in treating VIN could be improved by a better understanding of these apoptotic mechanisms, the influence of factors, such as HPV status, and of the need for effective pain management.

Asunto(s)

Asunto(s)

RESUMEN

OBJECTIVE: To assess the efficacy of using an iodized talc slurry as a sclerosing agent instilled into the pleural space via a 12-French pigtail catheter for controlling malignant pleural effusions. DESIGN: A prospective study in which patients were followed until their death. SETTING: A university-affiliated tertiary-care teaching hospital. PATIENTS: Medical oncology patients admitted with symptomatic malignant pleural effusions were considered for iodized talc pleurodesis. MAIN OUTCOME MEASURES: The control of pleural effusion. Treatment failure was defined as any reaccumulation of fluid in the pleural space. RESULTS: Fifteen patients were treated for a total of 17 instillations. The median follow-up on all patients until death was 6 months (range 1-20). The most frequent adverse effect in the study group was pleuritic chest pain (60%). The probability of control of effusion, as determined by the method of Kaplan-Meier, was 81% (SEM 9.7%). The cost of preparing 5 g of iodized talc was $4.32 (US). CONCLUSIONS: Iodized talc slurry instilled through a small-bore pigtail catheter is a safe, economical, and effective treatment for malignant pleural effusion.

Asunto(s)

RESUMEN

The physical and chemical stability of preservative-free meperidine hydrochloride solutions in polypropylene syringes was studied. Solutions of meperidine hydrochloride were diluted in dextrose 5% and normal saline to 0.25, 1, 10, 20, and 30mg/mL, repectively, and stored at either 22 deg C or 4 deg C for 28 days. All solutions were protected from light druing storage. Triplicate samples were taken from each syringe on days zero, one, three, seven, 14 and 28 and frozen at -72 deg C. Samples were analyzed in duplicate using a stability-indiicating high-pressure liquid chromatography assay. All samples remained colorless and free of precipitate throughout the course of the study. The concentration of meperidine remaining after the 28-day storage period was greater than 90% of the initial concentration for all the concentrations, diluents and temperatures studied.

Asunto(s)

Asunto(s)

Asunto(s)

Asunto(s)