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PubMed2000

Development of biodegradable films from whey proteins by cross-linking and entrapment in cellulose.

When cross-linked by heating or by gamma-irradiation and entrapped in cellulose, whey proteins can generate insoluble biofilms with good mechanical properties and high resistance to attack by proteolytic enzymes. Interchain cross-linking of proteins generated an increase in the puncture strength, and a decrease in water vapor permeability. Gelatin was added in film formulation as a stabilizer to improve the puncture strength and film appearance. The structure of the biofilms was also analyzed. SDS-PAGE revealed that heating and gamma-irradiation produce an increase of the molecular weight of the cross-linked protein. Size exclusion chromatography showed a molecular mass of 40 kDa for un-cross-linked whey proteins, whereas for the soluble fractions of the cross-linked proteins, molecular distributions were between 600 and 3800 kDa for the heated proteins and between 1000 and 2000 kDa for gamma-irradiated proteins. No major alteration of the structural conformation of the proteins was observed by FTIR for biofilms obtained after heat treatment, whereas gamma-irradiation induced some modifications in the protein structure. X-ray diffraction analysis suggests that cross-linking by gamma-irradiation seems to modify the conformation of proteins, which became more ordered and more stable.

Biodegradation, Environmental↗

PubMed1969

[Bronchiectasis. 250 cases].

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Adolescent↗

PubMedDate not supplied

Development of new jet injector for insulin therapy.

To improve diabetic patients' compliance to multiple injection protocols, we developed and tested a new insulin jet injector, the Preci-Jet 50. The prototype has the following features: small size (14 X 2 cm) and weight (160 g), capability of mixing two types of insulin, accuracy and reliability of the ejected volume (dose), ease of use and sterilization, simplicity of design, and capacity of adjusting jet pressure to individual skin resistance. The ejected volume, evaluated by gravimetry, was more accurate and more reliable with the injectors (N = 18) than with 0.5-cc disposable plastic syringes (N = 18). The dead space of the injectors (N = 16), as evaluated by isotopic recuperation of radioactive insulin, was minimal, allowing mixed insulin injections. The human-device interface evaluation demonstrated that diabetic patients (N = 13) learned easily to manipulate the injector and that their ability to use it properly improved after 1 mo of use. We conclude that this injector may be a practical tool for insulin-dependent diabetic patients.

Adult↗