A Simple Mathematical Model of Intradialytic Sodium Kinetics: “in vivo” Validation During Hemodialysis with Constant or Variable Sodium

A simple mathematical model of the intradialytic relationship between natraemia and dialysate sodium concentration is presented. The model includes a bicompartmental description of sodium, urea and fluid kinetics and an algebraic characterization of diffusive/convective mass-transfer across the dialysis membrane. Its ability to provide realistic responses has been validated comparing model predictions by a priori parameter tuning against quantities measured during in vivo sessions with both constant and variable dialysate sodium concentration. A quantitative analysis of model predictions indicates that the mean deviation between data calculated by the model and those measured in vivo is 1.32 mEq/l for sodium and 0.76 mmol/l for urea, values which do not greatly exceed the measurement errors of current instruments. The model's predictive capacity thus proves reliable. The ability of the model to calculate the amount of sodium removed and the time course of intra-extracellular volumes during the dialysis session makes it possible to forecast the patient's clinical tolerance to a given sodium dialysate concentration.

The aging population and Natural Occurring Retirement Communities (NORCs); local government, healthy aging, and healthy-NORCs

BACKGROUND

The term Naturally Occurring Retirement Communities (NORCs) has been used since the 1980s. NORCs are defined as communities where people remain or move to when they retire. NORCs develop 'naturally', meaning that seniors tend to remain or move there when they retire, although the residences and physical environment were not constructed for a senior population. The term, Healthy-NORC, has been introduced and is associated with healthy aging.

OBJECTIVES/METHODS

We describe how demographic trends will facilitate a dramatic growth in NORCs. Acknowledging the 'Determinants of Health' model, we suggest that some determinants impact people differently at different ages. We also suggest that more attention be focused on the impact of physical/social environments on health, and that some determinants of health are particularly relevant for seniors. We argue that NORCs exist on a spectrum, from NORC to H-NORC, and that health benefits for seniors increase as NORCs adopt additional characteristics associated with improved senior health. We also illustrate H-NORC research methods and policy options for local governments.

RESULTS/CONCLUSION

Compared to the provision of additional medical and social services, H-NORCs represent a low-cost approach to facilitating healthy aging. Municipal governments can promote healthy aging and should pursue policies that will stimulate H-NORC development.

Bridging the research gap: aboriginal and academic collaboration in FASD prevention. The Healthy Communities, Mothers and Children Project

OBJECTIVES

The objective was to assist with the prevention of Fetal Alcohol Spectrum Disorder through a participatory research approach involving local women and health care workers. Our interest was in understanding how well communities could develop culturally appropriate methods of helping women to reduce their alcohol consumption during pregnancy.

STUDY DESIGN

Four geographically distant Aboriginal communities were presented with a task of adapting a standard Brief Alcohol Intervention, and in particular to develop a culturally appropriate means of using the Intervention with women in the community.

METHODS

Academic and Aboriginal community researchers worked together in partnership, using a participatory action research approach to address alcohol use during pregnancy.

RESULTS

The outcome of the project was the design of four differing models of culturally appropriate community interventions designed to support vulnerable women in their childbearing years. The intervention models developed by the four communities have five core characteristics: (1) identification of women at risk; (2) assessment of the woman's drinking/ drug use; (3) provision of information to the women; (4) delivery method facilitates the decision to adopt healthier behaviors; and (5) means to monitor changes.

CONCLUSION

This project was considered successful in many respects: (1) each community developed a culturally-relevant prevention tool; (2) community involvement in the design lead to better understanding of its usefulness; (3) considerable knowledge exchange between academic and community partners took place; and (4) most importantly, it was found that community members can be active members in developing and implementing solutions to important public health issues.

A simple mathematical model of intradialytic sodium kinetics: "in vivo" validation during hemodialysis with constant or variable sodium

A simple mathematical model of the intradialytic relationship between natraemia and dialysate sodium concentration is presented. The model includes a bicompartmental description of sodium, urea and fluid kinetics and an algebraic characterization of diffusive/convective mass-transfer across the dialysis membrane. Its ability to provide realistic responses has been validated comparing model predictions by a priori parameter tuning against quantities measured during in vivo sessions with both constant and variable dialysate sodium concentration. A quantitative analysis of model predictions indicates that the mean deviation between data calculated by the model and those measured in vivo is 1.32 mEq/l for sodium and 0.76 mmol/l for urea, values which do not greatly exceed the measurement errors of current instruments. The model's predictive capacity thus proves reliable. The ability of the model to calculate the amount of sodium removed and the time course of intra-extracellular volumes during the dialysis session makes it possible to forecast the patient's clinical tolerance to a given sodium dialysate concentration.

High-performance liquid chromatographic profiles of aloe constituents and determination of aloin in beverages, with reference to the EEC regulation for flavouring substances

Characteristic HPLC profiles of fresh and aged aloe solutions, detected at 360 and 220 nm, are presented and compared. Several aloe constituents (aloesin, aloeresin A, hydroxyaloin, aloin A and B and aloinoside A and B) were simultaneously separated and identified. The determination of aloin is described (detection limit 0.15 ppm) and discussed. In aloe-based alcoholic beverages, the aloins could not be detected, owing to their instability and degradation in solution; this is discussed in relation to the EEC Council Directive 88/388, which fixed the values of maximum allowable concentrations for aloin in food and beverages. Instead of aloin, other aloe compounds (e.g., aloeresin A or aloesin) should perhaps be used as an index of the presence of aloe in alcoholic beverages.

Is vestibular papillomatosis associated with human papillomavirus?

The origin and clinical significance of vestibular papillae were evaluated by comparing histological features with the presence of human papillomavirus (HPV) types 6/11 and 16/18, as revealed by Southern blot DNA hybridization. Twenty women with vestibular papillomatosis underwent clinical evaluation and follow-up. When available, male partners were also examined. Histological changes suggestive of HPV infection were present in all the 20 specimens. Sixteen cases (80%) contained DNA sequences homologous to the viral probes. In particular, 12 cases (60%) reacted with the HPV 16/18 probe. Follow-up for more than 18 months revealed no variation in the distribution and appearance of vestibular papillae. No male partner showed signs of HPV lesions. The study shows that HPV 16 is frequently associated with vestibular papillae but does not support a productive infection. Therefore the most appropriate management of these patients should be evaluated clinically in each individual case.