Physicochemical properties and bacterial resistance of biodegradable milk protein films containing agar and pectin.

Free-standing sterilized edible films based on milk proteins, namely calcium caseinate and whey protein isolate, and polysaccharides, namely pectin and agar, were developed. Cross-linking of the proteins was achieved by the combination of thermal and radiative treatments. Autoclaving pectin and agar prior to their addition to the protein solutions generated films with an improved (P < or = 0.05) puncture strength. The presence of proteins and pectin-agar in the film formulation enhanced (P < or = 0.05) the moisture barrier of the films by 18%. A strain of Streptococcus thermophilus was used to assess the biodegradability behavior of the cross-linked films. Microbiological counts and soluble nitrogen analysis confirmed the biodegradability property of the milk protein films containing autoclaved pectin and agar.

Isothermal calorimetry study of calcium caseinate and whey protein isolate edible films cross-linked by heating and gamma-irradiation.

The contribution of thermal and radiative treatments as well as the presence of some excipients, namely glycerol, carboxymethylcellulose (CMC), pectin, and agar, on the formation of protein-protein interactions as well as the formation and loss of protein-water interactions was investigated by means of differential scanning calorimetry in an isothermal mode. Protein-water interactions were assessed through measurement of the heat of the wetting parameter. Isothermal calorimetry measurements pointed out that gamma-irradiation does not favor protein-water interactions, as reflected by its endothermic contribution (P < or = 0.05) to the heat of wetting values. Although significant (P < or = 0.05), the effect of the thermal treatment on endothermic responses using isothermal calorimetry was found to be somewhat lower. Among excipients added to biofilm formulations, glycerol generated the most important losses of protein-water interactions, as inferred by its significant (P < or = 0.05) endothermic impact on the heat of wetting values.

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.

Prevalence of spit tobacco use across studies of professional baseball players.

A review of published data, together with previously unpublished information, shows that the use of spit tobacco among professional baseball players continues to be alarmingly high. In spite of efforts to make players aware of the harmful effects, approximately 35 percent to 40 percent of professional baseball players still use spit tobacco, and about half of those have associated lesions. However, current efforts of the National Spit Tobacco Education Program, Major League Baseball, the Professional Baseball Athletic Trainers Society and the Major League Baseball Players Association are expected to result in a significant reduction in spit tobacco use in this population in the next decade.

A dental-based, athletic trainer-mediated spit tobacco cessation program for professional baseball players.

During 1997 spring training, the National Spit Tobacco Education Program provided a spit (smokeless) tobacco intervention program to 16 professional baseball clubs. The program consisted of an awareness-raising presentation and an opportunity to discuss quitting spit tobacco use with an expert cessation counselor. For two clubs, however, a more extensive intervention was pilot-tested for feasibility and acceptability among their major- and minor-league teams during their regularly scheduled health examinations at the beginning of spring training. The intervention included an oral exam by a dentist who advised spit tobacco users to stop and pointed out any spit tobacco-associated lesions in the player's mouth, brief cessation counseling by a specially trained dental hygienist, and ongoing support and follow-up by the certified athletic trainer to promote cessation. Findings from this pilot study indicate that this intervention, which is dependent upon involvement of dental professionals, was feasible to implement during spring training and appeared to be well-received by the athletes. Dental professionals are in an excellent position to advise and help spit tobacco users to quit and can have an important role in helping youth overcome this rapidly growing addiction.

A cyclin-dependent kinase inhibitor, Dacapo, is necessary for timely exit from the cell cycle during Drosophila embryogenesis.

In a screen for genes that interact with the Rap1 GTPase, we have identified a Drosophila gene, dacapo (dap), which is a member of the p21/p27 family of cdk inhibitors. Unlike mammalian cdk inhibitors studied to date, dap is essential for normal embryonic development. Dacapo inhibits cyclin-cdk activity in vitro. Overexpressing dap during eye development interferes with cell cycle progression and interacts genetically with the retinoblastoma homolog (Rbf) and cyclin E. dap expression in embryos parallels the exit of cells from the cell cycle. dap mutant embryos delay the normal cell cycle exit during development; many cells complete an additional cycle and subsequently become quiescent. Thus, dap functions during embryogenesis to achieve a precisely timed exit from the cell cycle.

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.