982 resultados para masque nasal


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Advertisements: p. [1] at end.

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Mode of access: Internet.

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"The name of this new heir to the Shakespearian mantle ... is that of ... Robert Devereux, second earl of Essex."--Introd.

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Mode of access: Internet.

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Objective To determine the efficacy and toxicity of chemotherapy in the treatment of canine nasal tumours. Design Retrospective clinical study Procedure Eight dogs with histologically confirmed nasal tumours were staged by means of complete blood count, serum biochemical analysis, cytological analysis of fine needle aspirate of the regional lymph nodes, thoracic radiographs and computed tomography scan of the nasal cavity. All dogs were treated with alternating doses of doxorubicin, carboplatin and oral piroxicam. All dogs were monitored for side effects of chemotherapy and evaluated for response to treatment by computed tomography scan of the nasal cavity after the first four treatments. Results Complete remission was achieved in four dogs, partial remission occurred in two dogs and two had stable disease on the basis of computed tomography evaluation. There was resolution of clinical signs after one to two doses of chemotherapy in all dogs. Conclusions This chemotherapy protocol was efficacious and well tolerated in this series of eight cases of canine nasal tumours.

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A 12-year-old male castrated Samoyed dog was presented with left-sided epistaxis and sneezing. Diagnostic procedures included haematology and biochemistry testing, thoracic radiography, fine needle aspiration of regional lymph nodes, CT, rhinoscopy, incisional biopsy and histopathology. Squamous cell carcinoma of the rostral nasal cavity was diagnosed, with no evidence of metastatic disease. External beam radiation was not an accessible treatment option. Complete surgical resection of the tumour would have required a larger, more disfiguring resection of nasal planum and maxilla than the owner was prepared to accept and may have been associated with an unacceptable morbidity. As an alternative, the extent of disease was reduced using a combination of carboplatin, doxorubicin and piroxicam chemotherapy. This allowed a less extensive nasal planum removal to be performed to remove residual disease with clean margins. The patient achieved a 14 month disease free interval from the time of surgery to the time of local recurrence. Survival time from diagnosis to eventual euthanasia for progressive local disease was 18 months.

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There is currently, no ideal system for studying nasal drug delivery in vitro. The existing techniques such as the Ussing chamber and cell culture all have major disadvantages. Most importantly, none of the existing techniques accurately represent the interior of the nasal cavity, with its airflow and humidity; neither do they allow the investigation of solid dosage forms.The work in this thesis represents the development of an in vitro model system in which the interior characteristics of the nasal cavity are closely represented, and solid or minimal volume dosage forms can be investigated. The complete nasal chamber consists of two sections: a lower tissue, viability chamber and an upper nasal chamber. The lower tissue viability chamber has been shown, using existing tissue viability monitoring techniques, to maintain the viability of a number of epithelial tissues, including porcine and rabbit nasal tissue, and rat ileal and Payers' patch tissue. The complete chamber including the upper nasal chamber has been shown to provide tissue viability for porcine and rabbit nasal tissue above that available using the existing Ussing chamber techniques. Adaptation of the complete system, and the development of the necessary experimental protocols that allow aerosol particle-sizing, together with videography, has shown that the new factors investigated, humidity and airflow, have a measurable effect on the delivered dose from a typical nasal pump. Similarly, adaptation of the chamber to fit under a confocal microscope, and the development of the necessary protocols has shown the effect of surface and size on the penetration of microparticulate materials into nasal epithelial tissues. The system developed in this thesis has been shown to be flexible, in allowing the development of the confocal and particle-sizing systems. For future nasal drug delivery studies, the ability to measure such factors as the size of the delivered system in the nasal cavity, the depth of penetration of the formulation into the tissue are essential. Additionally, to have access to other data such as that obtained from drug transport in the same system, and to have the tissue available for histological examination represents a significant advance in the usefulness of such an in vitro technique for nasal delivery.

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The nasal absorption of larger peptide and protein drugs is generally low. The importance of the mucus layer and enzymic degradation in reducing absorption were investigated. Reversed-phase high-performance liquid chromatographic (HPLC) methods were developed to assay a variety of compounds. Pig gastric mucus (PGM) was selected to investigate the importance of the mucus layer. A method of treating and storing PGM was developed and evaluated which was representative of the gel in vivo. The nature of the mucus barrier was evaluated in vitro with three-compartment diffusion cells and a series of compounds with differing physicochemical properties. Mucus retarded the diffusion of all the compounds with molecular weight and charge exerting a marked effect. Binding to mucus was investigated by a centrifugation method. All of the compounds tested were found to bind to mucus with the exception of the negatively charged molecule benzoic acid. The small peptides did not demonstrate greater binding to mucus than any of the other compounds evaluated. The effect of some absorption enhancers upon the rate of diffusion of tryptophan through mucus was determined in vi tro. At the concentrations employed the enhancers EDTA, N-acetylcysteine and taurodeoxycholic acid exerted no effect, whilst taurocholic acid and cholic acid, were found to slightly reduce the rate of diffusion. The intracellular and luminal proteolytic activity of the nose was investigated in the sheep animal model with a nasal mucosal homogenate and a nasal wash preparation respectively and a series of chemically similar peptides. Hydrolysis was also investigated with the proteolytic enzymes carboxypeptidase A, cytosolic leucine aminopeptidase and microsomal leucine aminopeptidase. Sheep nasal mucosa possesses significant peptide hydrolase activity capable of degrading all the substrates tested. Considerable variation in susceptibility was observed. Degradation occurred excl us i ve ly at the pept ide bond between the aromatic amino ac id and glycine, indicating some specificity for aromatic amino acids. Hydrolysis profiles indicated the presence of both aminopeptidase and carboxypeptidase enzymes. The specific activity of the microsomal fraction was found to be greater than the cytosolic fraction. Hydrolysis in the nasal wash indicated the presence of either luminal or loosely-bound proteases, which can degrade peptide substrates. The same specificity for aromatic amino acids was observed and aminopeptidase activity demonstrated. The specific activity of the nasal wash was smaller than that of the homogenate.