Exchangeable magnesium pool masses in healthy women: effects of magnesium supplementation.

BACKGROUND: Studying magnesium pools in the body with use of stable isotopes may be helpful for evaluating magnesium status. Data on the evaluation of magnesium pools in humans are scarce. OBJECTIVE: We undertook this study to evaluate the effects of a magnesium supplementation program on the size of the exchangeable body pools of magnesium and on classic indexes of magnesium status in healthy women with normal magnesium status. DESIGN: Ten healthy women participated in a kinetic study with magnesium stable isotopes before and after 8 wk of magnesium supplementation. Each woman received 3 supplements containing 5.08 mmol (122 mg) elemental Mg/d (366 mg/d). Before and at the end of the supplementation period, each woman received an intravenous injection of 1.67 mmol (40 mg) (25)Mg, and the plasma magnesium disappearance curve was followed for the next 7 d. Two methods were used to analyze the exchangeable pools of magnesium: 1) formal multicompartmental modeling and 2) a simplified estimation of the total mass of the rapidly exchangeable magnesium pool (EMgP). RESULTS: In these healthy women, exchangeable magnesium pools represented 11-12% of total body magnesium on the basis of multicompartmental analysis. The simplified estimation of EMgP overestimated the size of the exchangeable magnesium pools by approximately 45-50%. Eight weeks of magnesium supplementation did not significantly modify the size of the exchangeable magnesium pools, whereas urinary magnesium excretion was significantly higher after 8 wk of supplementation. CONCLUSION: Women with no clinical evidence of magnesium deficiency may not respond to short-term supplementation with increases in the mass of the exchangeable magnesium body pool or in magnesium turnover rates.     

Interstitial and vascular pancreas rejection in relation to graft survival

To examine the incidence of interstitial and vascular rejection in pancreas allografts and its impact on graft survival, we studied 36 percutaneous pancreas biopsies and 10 pancreas transplantectomy specimens from 32 patients who had undergone simultaneous pancreas-kidney transplantation. Interstitial rejection (IR) was predominantly found in the biopsies, while vascular rejection (VR) was most prominent in the transplantectomies. Pancreas graft survival was significantly decreased for pancreas grafts that had suffered from vascular rejection when compared to those with only interstitial rejection. Potential rejection markers, i. e., serum amylase, glucose, creatinine, and urinary amylase, did not correlate with histological signs of rejection, although increased levels of serum amylase were, in all but one case, associated with rejection.We conclude that a percutaneous pancreas biopsy remains the most reliable method to determine pancreas rejection, and that by distinguishing between IR andVR, a pancreas biopsy may provide important diagnostic as well as prognostic information. Received: 6 March 1997 Received after revision: 5 June 1997 Accepted: 30 June 1997     

Newly developed hybrid suture without lubricant: noninvasive in vivo assessment of biocompatibility with multiparametric MR imaging.

Magnetic resonance imaging (MRI) and magnetic resonance (MR) relaxometry were used to assess noninvasively the tissue response of a new uncoated hybrid braided suture made from a combination of ultra-high-molecular-weight polyethylene (UHMWPE) and polyester (polyethylene terephthalate) (PET) yarns in comparison to a silicone impregnated braided 100% polyester (PET) control suture (Ticron). Both biomaterials were monitored for a period of 30 days following implantation in both incised and nonincised paravertebral rabbit muscles. In all cases, MR images and relaxometry demonstrated that the hybrid suture elicited either a milder or a similar tissue and cellular response compared to the control suture. These findings were confirmed by conventional histological analysis of the surrounding tissues. They also demonstrated that the hybrid suture promoted faster healing in terms of collagen infiltration between the yarns and individual filaments. This milder inflammatory reaction and improved biocompatibility represent a real advantage in the healing performance of sutures for cardiac and vascular surgery, and support the need for continued research and development of hybrid structures. This study also demonstrated the ability of MRI techniques to noninvasively evaluate the biocompatibility of biomaterials. By extending the capacity of MR diagnostic tools from patients to experimental animals, it is now possible to validate the healing performance of foreign materials with statistical reliability and fewer animals.     

Challenges in accessing multidisciplinary pain treatment facilities in Canada

PURPOSE: The objective of this survey was to examine the services offered by multidisciplinary pain treatment facilities (MPTFs) across Canada and to compare access to care at these MPTFs. METHODS: A MPTF was defined as a clinic that advertised specialized multidisciplinary services for the diagnosis and management of patients with chronic pain, having a minimum of three different health care disciplines (including at least one medical speciality) available and integrated within the facility. The search method included approaching all hospital and rehabilitation centre administrators in Canada, the Insurance Bureau of Canada, the Workplace Safety and Insurance Board or similar body in each province. Designated investigators were responsible for confirming and supplementing MPTFs from the preliminary list for each province. Administrative leads at each eligible MPTF were asked to complete a detailed questionnaire regarding their MPTF infrastructure, clinical, research, teaching and administrative activities. RESULTS: Completed survey forms were received from 102 MPTFs (response rate 85%) with 80% concentrated in major cities, and none in Prince Edward Island and the Territories. The MPTFs offer a wide variety of treatments including non-pharmacological modalities such as interventional, physical and psychological therapy. The median wait time for a first appointment in public MPTFs is six months, which is approximately 12 times longer than non-public MPTFs. Eighteen pain fellowship programs exist in Canadian MPTFs and 64% engage in some form of research activities CONCLUSION: Canadian MPTFs are unable to meet clinical demands of patients suffering from chronic pain, both in terms of regional accessibility and reasonable wait time for patients' first appointment.