Chronic wound healing by controlled release of chitosan hydrogels loaded with silver nanoparticles and calendula extract.

As the skin is the main protective organ of the body, it is exposed to wounds or injuries which carry out a healing process during a period of approximately 15 days depending on the severity of the injury. In the present research, the development of chitosan-based hydrogels loaded with silver nanoparticles and calendula extract (Ch-AgNPs-Ce) was proposed. This can be used to fulfill the hemostatic, anti-infective, antibacterial, healing and anti-inflammatory functions through controlled release of the nanoparticles and calendula extract in substitution of commonly used drugs. The physical properties of the silver nanoparticles were analyzed by UV-visible spectroscopy, scanning and transmission electron microscopy, showing a size between 50 and 100 nm. The antibacterial properties were evaluated by the agar well diffusion method. Antimicrobial testing of the hydrogels showed that the inclusion of silver nanoparticles provides concentration-dependent antibacterial behavior against E. coli and S. aureus. The healing properties of the system were tested in two diabetic patients to whom said hydrogels were placed, obtaining a positive curative result after a few weeks. Therefore, it can be concluded that Ch-AgNPs-Ce hydrogels can achieve healing in chronic or exposed wounds after a period of time which can be used in alternative treatments in patients with poor healing capacity.

Mitochondrial ATPase activity and membrane fluidity changes in rat liver in response to intoxication with buckthorn (Karwinskia humboldtiana).

BACKGROUND: Karwinskia humboldtiana (Kh) is a poisonous plant of the rhamnacea family. To elucidate some of the subcellular effects of Kh toxicity, membrane fluidity and ATPase activities as hydrolytic and as proton-pumping activity were assessed in rat liver submitochondrial particles. Rats were randomly assigned into control non-treated group and groups that received 1, 1.5 and 2 g/Kg body weight of dry powder of Kh fruit, respectively. Rats were euthanized at day 1 and 7 after treatment. RESULTS: Rats under Kh treatment at all dose levels tested, does not developed any neurologic symptoms. However, we detected alterations in membrane fluidity and ATPase activity. Lower dose of Kh on day 1 after treatment induced higher mitochondrial membrane fluidity than control group. This change was strongly correlated with increased ATPase activity and pH gradient driven by ATP hydrolysis. On the other hand, membrane fluidity was hardly affected on day 7 after treatment with Kh. Surprisingly, the pH gradient driven by ATPase activity was significantly higher than controls despite an diminution of the hydrolytic activity of ATPase. CONCLUSIONS: The changes in ATPase activity and pH gradient driven by ATPase activity suggest an adaptive condition whereby the fluidity of the membrane is altered.

Calculating the metabolizable energy of macronutrients: a critical review of Atwater's results.

The current values for metabolizable energy of macronutrients were proposed in 1910. Since then, however, efforts to revise these values have been practically absent, creating a crucial need to carry out a critical analysis of the experimental methodology and results that form the basis of these values. Presented here is an exhaustive analysis of Atwater's work on this topic, showing evidence of considerable weaknesses that compromise the validity of his results. These weaknesses include the following: (1) the doubtful representativeness of Atwater's subjects, their activity patterns, and their diets; (2) the extremely short duration of the experiments; (3) the uncertainty about which fecal and urinary excretions contain the residues of each ingested food; (4) the uncertainty about whether or not the required nitrogen balance in individuals was reached during experiments; (5) the numerous experiments carried out without valid preliminary experiments; (6) the imprecision affecting Atwater's experimental measurements; and (7) the numerous assumptions and approximations, along with the lack of information, characterizing Atwater's studies. This review presents specific guidelines for establishing new experimental procedures to estimate more precise and/or more accurate values for the metabolizable energy of macronutrients. The importance of estimating these values in light of their possible dependence on certain nutritional parameters and/or physical activity patterns of individuals is emphasized. The use of more precise values would allow better management of the current overweight and obesity epidemic.

Mitochondrial ATPase activity and membrane fluidity changes in rat liver in response to intoxication with Buckthorn (Karwinskia humboldtiana)

BACKGROUND: Karwinskia humboldtiana (Kh) is a poisonous plant of the rhamnacea family. To elucidate some of the subcellular effects of Kh toxicity, membrane fluidity and ATPase activities as hydrolytic and as proton-pumping activity were assessed in rat liver submitochondrial particles. Rats were randomly assigned into control non-treated group and groups that received 1,1.5 and 2 g/Kg body weight of dry powder of Kh fruit, respectively. Rats were euthanized at day 1 and 7 after treatment. RESULTS: Rats under Kh treatment at all dose levels tested, does not developed any neurologic symptoms. However, we detected alterations in membrane fluidity and ATPase activity. Lower dose of Kh on day 1 after treatment induced higher mitochondrial membrane fluidity than control group. This change was strongly correlated with increased ATPase activity and pH gradient driven by ATP hydrolysis. On the other hand, membrane fluidity was hardly affected on day 7 after treatment with Kh. Surprisingly, the pH gradient driven by ATPase activity was significantly higher than controls despite an diminution of the hydrolytic activity of ATPase. CONCLUSIONS: The changes in ATPase activity and pH gradient driven by ATPase activity suggest an adaptive condition whereby the fluidity of the membrane is altered.