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Biodegradable magnesium (Mg) alloys exhibit improved mechanical properties compared to degradable polymers while degrading in vivo circumventing the complications of permanent metals, obviating the need for surgical removal. This study investigated the safety and efficacy of Mg-Y-Zn-Zr-Ca (WZ42) alloy compared to non-degradable Ti6Al4V over a 14-week follow-up implanted as pins to fix a full osteotomy in rat femurs and as wires wrapped around the outside of the femurs as a cerclage. We used a fully load bearing model allowing implants to intentionally experience realistic loads without immobilization. To assess systemic toxicity, blood cell count and serum biochemical tests were performed. Livers and kidneys were harvested to observe any accumulation of alloying elements. Hard and soft tissues adjacent to the fracture site were also histologically examined. Degradation behavior and bone morphology were determined using micro-computed tomography scans. Corrosion occurred gradually, with degradation seen after two weeks of implantation with points of high stress observed near the fracture site ultimately resulting in WZ42 alloy pin fracture. At 14 weeks however, normal bone healing was observed in femurs fixed with the WZ42 alloy confirmed by the presence of osteoid, osteoblast activity, and new bone formation. Blood testing exhibited no significant changes arising from the WZ42 alloy compared to the two control groups. No recognizable differences in the morphology and more importantly, no accumulation of Mg, Zn, and Ca in the kidney and liver of rats were observed. These load bearing model results collectively taken, thus demonstrate the feasibility for use of the Mg-Y-Zn-Zr-Ca alloy for long bone fracture fixation applications.

Elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide (E/C/F/TAF) is a potent fixed-dose, once-daily regimen for HIV-1 treatment and has rare emergence of drug resistance. We report a potential drug-drug interaction in 2 female patients both receiving treatment for HIV and cerebral toxoplasmosis: one case between E/C/F/TAF with calcium carbonate and a second case involving leucovorin as calcium salt. Both cases resulted in rise in HIV RNA levels and emergence of M184 V mutation and resistance to elvitegravir and raltegravir. To the best of our knowledge, these 2 cases are the first reports of rapid emergence of mutation from coadministration of E/C/F/TAF and calcium.

Background: Calciphylaxis is a rare disorder that is very unusual outside the setting of end-stage kidney disease., Case Summary: A 64-year-old woman with normal renal function presented with painful leg ulcers. She had previously received 300 000 IU of vitamin D 3 followed by daily calcium and vitamin D 3 supplementation. A skin biopsy was consistent with calciphylaxis, and she was treated with sodium thiosulphate infusions and wound debridement., Conclusion: Calcium and vitamin D 3 supplements are widely prescribed. We report a case of calciphylaxis triggered by calcium and vitamin D 3 supplementation in a patient with none of the typical risk factors. Our patient had an excellent response to treatment with sodium thiosulphate.

The authors report the case of a patient with symptomatic early bioprosthetic mitral valve deterioration in the setting of calcium supplementation. This was further complicated by a large left atrial thrombus despite supratherapeutic anticoagulation and a previously oversewn left atrial appendage. As mechanical valves are less predisposed to calcification in comparison with bioprosthetic implants, the patient underwent a mechanical mitral valve replacement in addition to a left atrial thrombectomy.

Objectives: Besides low mortality and morbidity rates in cardiac surgery, the associated cognitive dysfunction is the focus of interest. One possible reason is microembolisation., Methods and Results: The authors analysed the crystallogenesis in the calcium-containing prime, inspired by their observation that the fluid sometimes becomes turbid during the priming process. Lactated Ringer-based prime solutions were tested, adding mannitol, NaHCO(3), and heparin. The oxygenator was ventilated with compressed medical air. Samples were taken for dynamic light scattering particulate level analysis. The priming was furthermore modelled in the laboratory by mixing the components and then ventilating the mixture through with compressed air. Turbid solutions from the operating room contained 100-6500 nm crystals, while clear solutions contained 20-473 nm particles. In the model, continuous pH measurement showed pH 6.4-7.4 after blending the solutions, which then elevated the pH to 7.5-8.0 after ventilation with concomitant turbidity. The pH of the prime can be stabilized by the addition of ascorbic acid (1-2 mg/ml) and, also, the turbidity may be prevented., Conclusion: Ventilating the lactated Ringer-based calcium-containing primes after blending is not advisible because of alkalization and crystallogenesis. Ascorbic acid stabilizes the pH and prevents crystallogenesis in the prime. Pre-bypass filtration is recommended.

Background: One of the origins of cardiovascular disease in dialysis patients is arterial stiffness. The aim of our study was to assess the relationship between the calcium content of peritoneal dialysis (PD) solution and arterial stiffness., Patients and Methods: We enrolled into the study 49 PD patients who had been treated with the same PD solution for the preceding 6 months. The calcium content of the PD solution was 1.25 mmol/L in 34 patients (low-Ca group) and 1.75 mmol/L in 15 patients (high-Ca group). Study patients were followed for 6 months on the same PD prescription. Arterial stiffness was assessed by measurement of augmentation index (AI) and brachial pulse wave velocity (PWV) at baseline and at month 6 (SphygmoCor: Atcor Medical, West Ryde, NSW, Australia). Demographic data were recorded from patient charts., Results: Mean age of the whole group was 51 +/- 11 years, prevalence of diabetes was 14%, duration of PD was 43 +/- 30 months, percentage of women was 45%, and percentage of patients using a cycler was 33%. We observed no differences between groups with regard to those variables or creatinine clearance, residual renal function, Ca, phosphorus, parathormone, C-reactive protein, lipid parameters, and use of phosphate binder with or without Ca content. Mean arterial pressure was higher in the high-Ca group, but the difference was not statistically significant (100 +/- 22 mmHg vs 88 +/- 18 mmHg, p = 0.06). At baseline, AI was significantly higher in the high-Ca group than in the low-Ca group (27% +/- 10% vs 21% +/- 9%, p < 0.05). Measurements of PWV were not different between the groups (8.4 +/- 1.1 m/s vs 8.5 +/- 1.7 m/s). Measurement of arterial stiffness parameters at month 6 revealed that PWV had increased in the high-Ca group (to 9.6 +/- 2.3 m/s from 8.4 +/- 1.1 m/s, p < 0.05), but had not changed in the low-Ca group (to 8.2 +/- 1.9 m/s from 8.5 +/- 1.7 m/s). The AI did not change in either group., Conclusions: These data suggest that Ca exposure through PD solution plays a role in the progression of arterial stiffness, which may be related to increased vascular calcification.

Background: We previously reported a very high incidence of calciphylaxis, mainly in peritoneal dialysis (PD) patients. Although we identified several risk factors for the condition, including PD, we were unable to identify why our particular unit had such a high frequency of the condition and a reliable treatment., Objectives: To assess the apparent changing frequency of the condition and the response to therapy, and to attempt to determine putative factors that might explain our uniquely high incidence of calciphylaxis., Methods: A prospective clinical record was kept on all patients that developed calciphylaxis in our center [both PD and hemodialysis (HD) units] between 1998 and 2006., Results: Of the 59 patients that developed calciphylaxis, 54 were on PD, 4 were on HD, and 1 was in predialysis. In the PD population, the mean yearly incidence from 1998 to 2003 was 4.5/100 patient-years, falling to 1.3/100 patient-years in 2004-2006. The percent of patients not taking calcium salts fell during this time period. Conversion to HD led to marked early improvement. A marked discrepancy between the levels of ionized calcium (routinely used in our center) and corrected serum calcium was found, with most cases of hypercalcemia (corrected) being missed by using ionized values., Conclusions: The incidence of calciphylaxis is falling dramatically. This may be related partially to reduction in usage of calcium salts. Conversion to HD is beneficial. Our uniquely high incidence of calciphylaxis may be related to our use of ionized calcium levels to monitor these patients.

Objective: To investigate the risk factors for the development of calciphylaxis in renal failure, a poorly understood and often fatal condition characterized by calcium deposition in tissues., Design: Retrospective case-control study., Setting: University hospital peritoneal dialysis center., Patients: Eight continuous ambulatory peritoneal dialysis (CAPD) patients with calciphylaxis were identified in a 3-year period. We matched up to five controls for dialysis modality and length of time on dialysis with each case., Statistics: Multivariate conditional logistic regression analysis for matched case-controls., Main Outcome Measures: Laboratory data and demographics were collected as well as cumulative calcium and vitamin D ingestion over the year prior to disease onset., Results: All the patients were female, versus only 38% (14/37) of controls (p < 0.0001). While not statistically significant, a majority of the patients were diabetic [62.5% (5/8) vs 32% (12/37)]. Peak and average levels of serum calcium, phosphate, calcium x phosphate product, parathyroid hormone (PTH), albumin, iron, total iron-binding capacity (TIBC), and ferritin were not significantly different in cases compared with controls. The use of calcitriol alone or with calcium carbonate was not found to be a significant risk factor for the development of calciphylaxis. In a multivariate analysis, iron intake seemed to be protective, contrary to previous reports, while the use of calcium carbonate was associated with a strong trend to increased risk of calciphylaxis development (odds ratio = 1.029/g and 1.011/g calcium ingested per month, at 1 and 2 - 3 months prior to calciphylaxis development; p = 0.0556 and 0.0565, respectively)., Conclusion: These data, although limited by the small numbers of index cases, suggest that calcium ingestion is a risk factor for calciphylaxis. The increased use of calcium salts as a phosphate binder in recent years might explain the apparent increased incidence of calciphylaxis in our and other centers. The preponderance of female diabetics among cases reported elsewhere was confirmed in our study.

A retrospective study in coronary artery bypass graft patients was undertaken to assess the effect of gentamicin and a bypass prime with a high calcium on the incidence of renal failure. Patients who received both Haemaccel (polygeline, Hoechst Marion Roussel) (calcium concentration 6.25 mmol/l) in the bypass prime and gentamicin perioperatively had a higher incidence of renal failure compared with those who received only Haemaccel (P = 0.005), only gentamicin (P = 0.002) or neither (P = 0.0001). We suggest that the combination be avoided in this group of patients.

Calcium has a fundamental role in the maintenance of myocardial function and vascular tone. The ionized form of calcium is the most important physiologically, and this form needs to be measured to assess physiologically active calcium levels. Ionized hypocalcemia can occur as a result of various pathophysiological disturbances, and it is seen frequently in critically ill patients. Several investigators have observed a poorer prognosis in those patients with ionized hypocalcemia. It is unclear whether calcium supplementation is beneficial in these patients. It may improve cardiovascular performance, but, in contrast, it may contribute to cellular damage (especially during hypoxia following cardiopulmonary resuscitation). In sepsis, there may be an increased cellular influx of calcium, which may be deleterious to cellular function; indeed, calcium entry blockers in this situation may be protective. We review the role of calcium as an inotropic agent, its interaction with other inotropic agents, and its use during blood transfusion and during cardiopulmonary resuscitation.

Parathyroid cysts are uncommon. They can be divided into functional and nonfunctional cysts depending on whether or not they are associated with hypercalcemia. Functioning cysts are very rare with less than twenty reported cases. We report a case of functioning parathyroid cyst associated with hypocalciuric hypercalcemia. We have been unable to find a similar case previously reported in the literature.