Liquid-core nanocellulose-shell capsules with tunable oxygen permeability.

Encapsulation of oxygen sensitive components is important in several areas, including those in the food and pharmaceutical sectors, in order to improve shelf-life (oxidation resistance). Neat nanocellulose films demonstrate outstanding oxygen barrier properties, and thus nanocellulose-based capsules are interesting from the perspective of enhanced protection from oxygen. Herein, two types of nanocellulose-based capsules with liquid hexadecane cores were successfully prepared; a primary nanocellulose polyurea-urethane capsule (diameter: 1.66 µm) and a bigger aggregate capsule (diameter: 8.3 µm) containing several primary capsules in a nanocellulose matrix. To quantify oxygen permeation through the capsule walls, an oxygen-sensitive spin probe was dissolved within the liquid hexadecane core, allowing non-invasive measurements (spin-probe oximetry, electron spin resonance, ESR) of the oxygen concentration within the core. It was observed that the oxygen uptake rate was significantly reduced for both capsule types compared to a neat hexadecane solution containing the spin-probe, i.e. the slope of the non-steady state part of the ESR-curve was approximately one-third and one-ninth for the primary nanocellulose capsule and aggregated capsule, respectively, compared to that for the hexadecane sample. The transport of oxygen was modeled mathematically and by fitting to the experimental data, the oxygen diffusion coefficients of the capsule wall was determined. These values were, however, lower than expected and one plausible reason for this was that the ESR-technique underestimate the true oxygen uptake rate in the present systems at non-steady conditions, when the overall diffusion of oxygen was very slow.

Preparation of gold nanoparticles in an aqueous medium using 2-mercaptosuccinic acid as both reduction and capping agent.

Monolayer protected gold nanoparticles with diameters above 10 nm were prepared by a simple, one step reaction in water. 2-mercaptosuccinic acid (MSA) was used both as reduction agent for hydrogen tetrachloroaurate (HAuCl4) and as stabilizing agent for the gold nanoparticles. Size distribution and surface chemistry were investigated by UV-Vis spectroscopy, scanning electron microscopy and Fourier Transform Infrared Spectroscopy. Particle size can be controlled by adjusting the molar portions of the reactants. The resulting particles are efficiently stabilized against aggregation when MSA is used in a concentration of 40% and above. Below a minimum MSA concentration a long-term particle growth is observed.

Comparison of antioxidative capacities and inhibitory effects on cholesterol biosynthesis of quercetin and potential metabolites.

The flavonol quercetin is known to be rapidly metabolized after ingestion by enterocytes and bacteria in the intestinal tract which may influence the biological, e.g. antioxidative potency of this compound. Therefore, quercetin and several of its possible metabolites were compared with regard to their antioxidant activity and their capacity to inhibit hepatocellular cholesterol biosynthesis. Using the 2,2,-diphenylpicrylhydrazyl radical scavenger assay, all compounds with an ortho diphenolic structure acted as strong antioxidants. In contrast, in a cellular assay focusing on lipid peroxidation in cultured rat hepatocytes challenged with tert.-butylhydroperoxide only the lipophilic compounds quercetin and 3,4-dihydroxytoluene were active. Concerning the inhibition of cholesterol biosynthesis, 3,4-dihydroxytoluene surprisingly mimicked the effect of quercetin in primary rat hepatocytes, but much less so in HepG2 cells. All other metabolites were almost ineffective in both cell types. These results suggest that some of the biological functions of flavonoids detectable by in vitro assays may persist in vivo as long as comparably potent metabolites are systemically present.

Heterogeneous expression of mRNA in rat liver lobules as detected by differential display.

Although liver hepatocytes appear to be uniform histologically, they are considerably heterogeneous with respect to their individual physiological capacities. In order to find still unknown genes that are heterogeneously expressed and with the aim of evaluating the usefulness of the differential display technique for this purpose, we performed differential displays with mRNA isolated from hepatocytes from the periportal and pericentral zone of the rat liver. In this way we identified at least two mRNAs exclusively expressed in the pericentral fraction. Sequence analysis revealed that the corresponding genes encode proteins with proline-glutamate dipeptide repeats similar to ones previously identified in rat pheochromocytoma and brain. In situ hybridization confirmed the heterogeneous distribution of the mRNA. Only one to two cell lines surrounding the terminal hepatic venules were positive, strongly resembling the heterogeneous expression of the enzyme glutamine synthetase. Our work demonstrates that the differential display method is a useful tool for the identification of genes that are differentially expressed in individual parenchymal cells. In fact, our results prove that differential display technology can be used for the identification of cellular markers for distinct subpopulations of cells in a given tissue.

The linkage of Baltimore's mental health and public health systems.

The Institute of Medicine's The Future of Public Health calls for a strengthening of linkages between public health and mental health, with a view to integrating the functions at the service delivery level. This paper details the history of the mental health/public health interface in Baltimore, Maryland. In 1977, mental health and addiction services were merged into the Department of Health. More recently, in 1988 adult mental health services were split off into a quasi-public corporation. Children's mental health, however, was retained as a distinct service within the Department of Health in order to enhance coordination with other health services for children. Replication of such coordinated-care models is certainly feasible.

The ethics committee in the nursing home. Results of a national survey.

As the complexity, prevalence and visibility of ethical dilemmas in medical care of the elderly have grown, hospitals and nursing homes have attempted to develop mechanisms for responding to these difficult ethical issues. While it is known that many hospitals rely on education and advice provided by an ethics committee, little data exist on the responses of nursing homes, despite the unique nature of ethical issues in a long-term care setting. The present paper reports findings from a national survey of administrators of 4504 nursing homes in which mechanisms for handling ethical dimensions in patient care were investigated. Results from 29% of respondents reveal that few nursing homes have established ethics committees (2% of the sample) and that committee formation appears positively associated with facility size and religious affiliation. Committees that have been formed engage in policy review (81%), advisory case review (67%) and education (45%). Few committees include patients or their representatives as members, and few have the authority to make binding decisions (26%). While the most effective response to ethical issues in medical decision-making is being debated, standing committees provide one means to contribute to the quality of decision-making by patients, their family members and their physicians. However, broader inclusion of patient perspectives and education of members regarding ethical analysis are necessary precursors to effective functioning of ethics committees in long-term care.