Research progress on the application of magnesium phosphate bone cement in bone defect repair: A review

BACKGROUND

Bone defects arising from diverse causes, such as traffic accidents, contemporary weapon usage, and bone-related disorders, present significant challenges in clinical treatment. Prolonged treatment cycles for bone defects can result in complications, impacting patients' overall quality of life. Efficient and timely repair of bone defects is thus a critical concern in clinical practice.

OBJECTIVE

This study aims to assess the scientific progress and achievements of magnesium phosphate bone cement (MPC) as an artificial bone substitute material. Additionally, the research seeks to explore the future development path and clinical potential of MPC bone cement in addressing challenges associated with bone defects.

METHODS

The study comprehensively reviews MPC's performance, encompassing e.g. mechanical properties, biocompatibility, porosity, adhesion and injectability. Various modifiers are also considered to broaden MPC's applications in bone tissue engineering, emphasizing drug-loading performance and antibacterial capabilities, which meet clinical diversification requirements.

RESULTS

In comparison to alternatives such as autogenous bone transplantation, allograft, polymethyl methacrylate (PMMA), and calcium phosphate cement (CPC), MPC emerges as a promising solution for bone defects. It addresses limitations associated with these alternatives, such as immunological rejection and long-term harm to patients. MPC can control heat release during the curing process, exhibits superior mechanical strength, and has the capacity to stimulate new bone growth.

CONCLUSION

MPC stands out as an artificial bone substitute with appropriate mechanical strength, rapid degradation, non-toxicity, and good biocompatibility, facilitating bone repair and regeneration. Modification agents can enhance its clinical versatility. Future research should delve into its mechanical properties and formulations, expanding clinical applications to create higher-performing and more medically valuable alternatives in bone defect repair.

d,l-Methionine in combination with amoxicillin-clavulanic acid successfully dissolves spontaneously occurring infection-induced struvite urocystoliths in dogs: a pilot study

OBJECTIVE

To determine the efficacy and safety of a urinary acidifier (d,l-methionine [Methio-Form]) and an antimicrobial agent (amoxicillin-clavulanic acid [Clavamox]) without changing diet for dissolving infection-induced struvite urocystoliths in dogs.

ANIMALS

14 dogs were recruited for this prospective study; 11 completed it and 3 dogs withdrew due to inability of the owners to administer the treatment (n = 2) or refusal of treatment by the dog (1).

PROCEDURES

All dogs were administered d,l-methionine (approx initial dose of 75 mg/kg, PO, q 12 h) and amoxicillin-clavulanic acid (22 mg/kg, PO, q 12 h) based on urine culture and sensitivity. Urine pH, urinalysis, urine culture, venous blood gas and serum biochemical analysis, and lateral survey abdominal radiographic images were evaluated initially and every 4 weeks until urolith dissolution (success) or lack of change in size and/or shape of urocystoliths on 2 consecutive reevaluation points (failure) occurred.

RESULTS

Uroliths dissolved in 8 of 11 dogs in a median of 2 months (range, 1 to 4 months) with a final effective dosage of d,l-methionine of approximately 100 mg/kg, PO, every 12 hours. In 3 dogs, uroliths failed to dissolve and were removed surgically; they contained variable amounts of calcium oxalate. No adverse events occurred.

CLINICAL RELEVANCE

Infection-induced struvite urolithiasis is 1 of the 2 most common minerals occurring in canine uroliths. Results of this study supported the use of d,l-methionine and amoxicillin-clavulanic acid without changing diet for dissolution of infection-induced struvite urocystoliths in dogs.

GEO-PGS composite shows synergistic and complementary effect on Escherichia coli and improvement of intestinal dysfunction

Palygorskite (PGS) is a kind of clay minerals with the property of absorbent capacity, and ginger essential oil (GEO) is a kind of natural antibacterial substances. In the present study PGS was used as carrier of GEO, and thus, a kind of new anti-bacterial composite GEO-PGS has been obtained. Characterization, inhibitory effect of GEO-PGS on Escherichia coli (E. coli) and its function of improvement of intestinal health would be investigated. Results showed that characterization analysis of GEO-PGS (FTIR, TG-DSC, BET, Zeta potential, specific surface area, total pore volume and size, TEM observation) demonstrated combination of GEO and PGS, and GEO was absorbed on the surface of PGS, partially filled the micropores of PGS. GEO-PGS had obvious inhibitory effect on E.coli, in combination of the antibacterial activity of GEO and bacteria-absorbed capability of PGS. GEO-PGS also had ameliorating effect on enteritis and intestinal dysfunction in vivo, which might be related to the inhibition of gene expression of inflammatory cytokines (TLR2, IL-6, TNFα, and IL-8). In conclusion, the novel composite GEO-PGS has the potential usage as functional component having effect of improving intestinal health.

Control of metabolic predisposition to cardiovascular complications of chronic kidney disease by effervescent calcium magnesium citrate: a feasibility study

Aims

Cardiovascular (CV) complications are common in chronic kidney disease (CKD). Numerous metabolic disturbances including hyperphosphatemia, high circulating calciprotein particles (CPP), hyperparathyroidism, metabolic acidosis, and magnesium deficiency are associated with, and likely pathogenic for CV complications in CKD. The goal of this feasibility study was to determine whether effervescent calcium magnesium citrate (EffCaMgCit) ameliorates the aforementioned pathogenic intermediates.

Methods

Nine patients with Stage 3 and nine patients with Stage 5D CKD underwent a randomized crossover study, where they took EffCaMgCit three times daily for 7 days in one phase, and a conventional phosphorus binder calcium acetate (CaAc) three times daily for 7 days in the other phase. Two-hour postprandial blood samples were obtained on the day before and on the 7th day of treatment.

Results

In Stage 5D CKD, EffCaMgCit significantly increased T50 (half time for conversion of primary to secondary CPP) from baseline by 63% (P = 0.013), coincident with statistically non-significant declines in serum phosphorus by 25% and in saturation of octacalcium phosphate by 35%; CaAc did not change T50. In Stage 3 CKD, neither EffCaMgCit nor CaAc altered T50. With EffCaMgCit, a significant increase in plasma citrate was accompanied by statistically non-significant increase in serum Mg and phosphate. CaAc was without effect in any of these parameters in Stage 3 CKD. In both Stages 3 and 5D, both drugs significantly reduced serum parathyroid hormone. Only EffCaMgCit significantly increased serum bicarbonate by 3 mM (P = 0.015) in Stage 5D.

Conclusions

In Stage 5D, EffCaMgCit inhibited formation of CPP, suppressed PTH, and conferred magnesium and alkali loads. These effects were unique, since they were not observed with CaAc. In Stage 3 CKD, neither of the regimens have any effect. These metabolic changes suggest that EffCaMgCit might be useful in protecting against cardiovascular complications of CKD by ameliorating pathobiologic intermediates.

Electroacupuncture plus standard of care for managing refractory functional dyspepsia: protocol of a pragmatic trial with economic evaluation

INTRODUCTION

This trial proposes to compare the effectiveness and cost-effectiveness of electroacupuncture (EA) plus on-demand gastrocaine with waiting list for EA plus on-demand gastrocaine in providing symptom relief and quality-of-life improvement among patients with functional dyspepsia (FD).

METHODS AND ANALYSIS

This is a single-centre, pragmatic, randomised parallel-group, superiority trial comparing the outcomes of (1) EA plus on-demand gastrocaine group and (2) waiting list to EA plus on-demand gastrocaine group. 132 (66/arm) endoscopically confirmed, Helicobacter pylori-negative patients with FD will be recruited. Enrolled patients will respectively be receiving (1) 20 sessions of EA over 10 weeks plus on-demand gastrocaine; or (2) on-demand gastrocaine and being nominated on to a waiting list for EA, which entitles them 20 sessions of EA over 10 weeks after 12 weeks of waiting. The primary outcome will be the between-group difference in proportion of patients achieving adequate relief of symptoms over 12 weeks. The secondary outcomes will include patient-reported change in global symptoms and individual symptoms, Nepean Dyspepsia Index, Nutrient Drink Test, 9-item Patient Health Questionnaire (PHQ9), and 7-item Generalised Anxiety Disorder Scale (GAD7). Adverse events will be assessed formally. Results on direct medical costs and on the EuroQol (EQ-5D) questionnaire will also be used to assess cost-effectiveness. Analysis will follow the intention-to-treat principle using appropriate univariate and multivariate methods. A mixed model analysis taking into account missing data of these outcomes will be performed. Cost-effectiveness analysis will be performed using established approach.

ETHICS AND DISSEMINATION

The study is supported by the Health and Medical Research Fund, Government of the Hong Kong Special Administrative Region of China. It has been approved by the Joint Chinese University of Hong Kong - New Territories East Cluster Clinical Research Ethics Committee. Results will be published in peer-reviewed journals and be disseminated in international conference.

TRIAL REGISTRATION NUMBER

ChiCTR-IPC-15007109; Pre-result.

Efficacy of Medical Expulsive Therapy in Renal Calculi Less than or Equal to 5 Millimetres in Size

PURPOSE

Natural history and modality of treatment for asymptomatic renal calculi less than or equal to 5 millimetres in size is still unknown. Many options are available ranging from medical expulsive therapy to minimally invasive surgery. Till date no study has focussed on this very common but asymptomatic issue. Hence, this study is undertaken to evaluate efficacy of medical expulsive therapy in renal calculi less than or equal to 5mm in size.

MATERIALS AND METHODS

A prospective, parallel group, randomized study was carried out from 1st June 2014 to 31st May 2015, with total of 100 patients, 50 patients in each group. Patients with renal stones less than or equal to 5mm were included in the study. Group A Patients were administered medical expulsive therapy which included  tamsulosin 0.4 mg daily at night time, furosemide 20mg, spironolactone 50mg in a single morning dose, and syrup potassium magnesium citrate 20Meq per dose three times a day for 12 weeks while group B patients were given placebo. The primary outcome variable was number of patients achieving clearance of stone during 12-week treatment period in both groups.

RESULTS

No statistically significant differences in age, gender, stone size, and calyceal stone location was found between the two treatment arms. A spontaneous stone expulsion rate of 50% (at 6 weeks) and 86 %( at 12 weeks) was noted in group A versus 28% (at 6 weeks) and 38 % (at 12 weeks) in group B. Less number of pain episodes and less analgesic medication was required in group A as compared to group B.

CONCLUSION

Medical Expulsive therapy for 12 weeks significantly improves stone free rates in renal calyceal calculi less than or equal to 5mm.

Citrate salts for preventing and treating calcium containing kidney stones in adults

BACKGROUND

Kidney stones affect people worldwide and have a high rate of recurrence even with treatment. Recurrences are particularly prevalent in people with low urinary citrate levels. These people have a higher incidence of calcium phosphate and calcium oxalate stones. Oral citrate therapy increases the urinary citrate levels, which in turn binds with calcium and inhibits the crystallisation thus reduces stone formation. Despite the widespread use of oral citrate therapy for prevention and treatment of calcium oxalate stones, the evidence to support its clinical efficacy remains uncertain.

OBJECTIVES

The objective of this review was to determine the efficacy and adverse events associated with citrate salts for the treatment and prevention of calcium containing kidney stones.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Specialised Register to 29 July 2015 through contact with the Trials' Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) that assessed the efficacy and adverse events associated with citrate salts for the treatment and prevention of calcium containing kidney stones in adults treated for a minimum of six months.

DATA COLLECTION AND ANALYSIS

Two authors assessed studies for inclusion in this review. Data were extracted according to predetermined criteria. Summary estimates of effect were obtained using a random-effects model, and results were expressed as risk ratios (RR) and their 95% confidence intervals (CI) for dichotomous outcomes, and mean difference (MD) and 95% CI for continuous outcomes.

MAIN RESULTS

We included seven studies that included a total of 477 participants, most of whom had oxalate stones. Of these, three studies (247 participants) compared potassium citrate with placebo or no intervention; three (166 participants) compared potassium-sodium citrate with no intervention; and one (64 participants) compared potassium-magnesium citrate with placebo. Overall, quality of the reporting of the included studies was considered moderate to poor, and there was a high risk of attrition bias in two studies.Compared with placebo or no intervention, citrate therapy significantly reduced the stone size (4 studies, 160 participants: RR 2.35, 95% CI 1.36 to 4.05). New stone formation was significantly lower with citrate therapy compared to control (7 studies, 324 participants: RR 0.26, 95% CI 0.10 to 0.68). The beneficial effect on stone size stability was also evident (4 studies, 160 participants: RR 1.97, 95% CI 1.19 to 3.26). Adverse events were reported in four studies, with the main side effects being upper gastrointestinal disturbance and one patient reported a rash. There were more gastrointestinal adverse events in the citrate group; however this was not significant (4 studies, 271 participants: RR 2.55, 95% CI 0.71 to 9.16). There were significantly more dropouts due to adverse events with citrate therapy compared to control (4 studies, 271 participants: RR 4.45, 95% CI 1.28 to 15.50). The need for retreatment was significantly less with citrate therapy compared to control (2 studies, 157 participants: RR 0.22, 95% CI 0.06 to 0.89).

AUTHORS' CONCLUSIONS

Citrate salts prevent new stone formation and reduce further stone growth in patients with residual stones that predominantly contain oxalate. The quality of reported literature remains moderate to poor; hence a well-designed statistically powered multi-centre RCT is needed in order to answer relevant questions concerning the efficacy of citrate salts.

Effects of Systemic Magnesium on Post-operative Analgesia: Is the Current Evidence Strong Enough?

BACKGROUND

Clinical studies have been previously carried out on the efficacy of systemic magnesium to minimize postoperative pain, however, with controversial results. A quantitative meta-analysis was performed to evaluate the analgesic efficacy and safety of systemic magnesium on post-operative pain.

STUDY DESIGN

Comprehensive systematic review of all relevant, publsished randomized controlled trials.

METHODS

A search was conducted of published literature in MEDLINE, PsycINFO, Scopus, EMBASE, and the Cochrane Central Register of Controlled Trials (CENTRAL) databases from inception to Sep-Oct 2014. Randomized controlled trials (RCTs) that compared magnesium with placebo were identified. Effects were summarized using standardized mean differences (SMDs), weighed mean differences (WMD), or odds ratio (OR) with suitable effect model.

RESULTS

Twenty-seven RCTs involving 1,504 patients were included. In total, peri-operative magnesium significantly reduced the pain score at rest (SMD, -1.43, 95% CI, -2.74 to -0.12, < 0.01). Magnesium significantly reduced analgesic consumption (SMD, -1.72, 95% CI, -3.21 to -0.23) in patients undergoing urogenital, orthopaedic, and cardiovascular surgeries, but was inconclusive for patients receiving gastrointestinal surgeries. The obvious analgesia of systemic magnesium was observed on reducing the pain score during movement at 24 hours after operation (SMD, -0.05, 95% CI, -0.43 to 0.32). Moreover, magnesium administration showed a beneficial effect with regard to intra-operative hemodynamics and reduced extubation time in the cardiovascular surgery patients (WMD, -29.34 min, 95% CI, -35.74 to -22.94, P < 0.01).

LIMITATIONS

Focused only on the quality of analgesia on postoperative pain with regards to surgery type.

CONCLUSIONS

Our study suggests that systemic magnesium during general anesthesia significantly decreases post-operative pain scores without increasing adverse events. It should be noted that since there are 18 ongoing RCTs without published data, it is still premature to draw conclusions on the long-term analgesic effects of magnesium as well as potential gender or age difference.

The use of a magnesium-based bone cement to secure immediate dental implants

PURPOSE

The use of a magnesium-based bone cement, OsteoCrete, has shown promise as a means to secure bone and tendon-to-bone connections in orthopedic medicine. The presence of a bone cement to fill the residual socket and stabilize a dental implant during healing could make immediate implant placement in molar sites more predictable. The aim of this study was to determine whether this magnesium-based bone cement can be used predictably for this purpose.

MATERIALS AND METHODS

The mandibular third premolars and first molars were extracted bilaterally from four mongrel dogs (60 to 80 lb each). Implants were placed in each extraction socket and supported by only 2 to 3 mm of apical furcation bone. OsteoCrete bone cement was placed randomly for implant stabilization in half of the sites. Clinical healing was evaluated until the 4-month time point. All animals were then sacrificed, and mandibular en bloc resection was performed for histologic evaluation of the biologic response and bone-to-implant contact.

RESULTS

Clinically, healing showed a poor response when the test site implant was left exposed in a one-stage manner. No statistically significant difference was noted in bone-to-implant contact (52% in test sites versus 44% in control sites). Histologic specimens showed no adverse biologic response to the material but only minimal replacement at 4 months.

CONCLUSIONS

OsteoCrete bone cement was successful in stabilizing the immediate dental implant in a large extraction socket when placed in a closed environment in the dog model but did not show a benefit as compared to controls. The limited data warrant further studies to determine the further potential of this material.

Magnesium maintenance therapy for preventing preterm birth after threatened preterm labour

BACKGROUND

Magnesium maintenance therapy is one of the types of tocolytic therapy used after an episode of threatened preterm labour (usually treated with an initial dose of tocolytic therapy) in an attempt to prevent the onset of further preterm contractions.

OBJECTIVES

To assess whether magnesium maintenance therapy is effective in preventing preterm birth after the initial threatened preterm labour is arrested.

SEARCH METHODS

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (31 January 2013).

SELECTION CRITERIA

Randomised controlled trials of magnesium therapy given to women after threatened preterm labour.

DATA COLLECTION AND ANALYSIS

The review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. We checked data entry.

MAIN RESULTS

We included four trials involving 422 women. Three trials had high risk of bias and none included any long-term follow-up of infants. No differences in the incidence of preterm birth or perinatal mortality were seen when magnesium maintenance therapy was compared with placebo or no treatment; or alternative therapies (ritodrine or terbutaline). The risk ratio (RR) for preterm birth (less than 37 weeks) for magnesium compared with placebo or no treatment was 1.05, 95% confidence interval (CI) 0.80 to 1.40 (two trials, 99 women); and 0.99, 95% CI 0.57 to 1.72 (two trials, 100 women) for magnesium compared with alternative therapies. The RR for perinatal mortality for magnesium compared with placebo or no treatment was 5.00, 95% CI 0.25 to 99.16 (one trial, 50 infants); and 5.00, 95% CI 0.25 to 99.16 (one trial, 50 infants) for magnesium compared with alternative treatments.Women taking magnesium preparations were less likely to report side effects (RR 0.67, 95% CI 0.47 to 0.96, three trials, 237 women), including palpitations or tachycardia (RR 0.26, 95% CI 0.13 to 0.52, three trials, 237 women) than women receiving alternative therapies. Women receiving magnesium were however, more likely to experience diarrhoea (RR 6.79, 95% CI 1.26 to 36.72, three trials, 237 women).

AUTHORS' CONCLUSIONS

There is not enough evidence to show any difference between magnesium maintenance therapy compared with either placebo or no treatment, or alternative therapies (ritodrine or terbutaline) in preventing preterm birth after an episode of threatened preterm labour.

Interventions for preventing post-operative atrial fibrillation in patients undergoing heart surgery

BACKGROUND

Atrial fibrillation is a common post-operative complication of cardiac surgery and is associated with an increased risk of post-operative stroke, increased length of intensive care unit and hospital stays, healthcare costs and mortality. Numerous trials have evaluated various pharmacological and non-pharmacological prophylactic interventions for their efficacy in preventing post-operative atrial fibrillation. We conducted an update to a 2004 Cochrane systematic review and meta-analysis of the literature to gain a better understanding of the effectiveness of these interventions.

OBJECTIVES

The primary objective was to assess the effects of pharmacological and non-pharmacological interventions for preventing post-operative atrial fibrillation or supraventricular tachycardia after cardiac surgery. Secondary objectives were to determine the effects on post-operative stroke or cerebrovascular accident, mortality, cardiovascular mortality, length of hospital stay and cost of treatment during the hospital stay.

SEARCH METHODS

We searched the Cochrane Central Register of ControlLed Trials (CENTRAL) (Issue 8, 2011), MEDLINE (from 1946 to July 2011), EMBASE (from 1974 to July 2011) and CINAHL (from 1981 to July 2011).

SELECTION CRITERIA

We selected randomized controlled trials (RCTs) that included adult patients undergoing cardiac surgery who were allocated to pharmacological or non-pharmacological interventions for the prevention of post-operative atrial fibrillation or supraventricular tachycardia, except digoxin, potassium (K(+)), or steroids.

DATA COLLECTION AND ANALYSIS

Two review authors independently abstracted study data and assessed trial quality.

MAIN RESULTS

One hundred and eighteen studies with 138 treatment groups and 17,364 participants were included in this review. Fifty-seven of these studies were included in the original version of this review while 61 were added, including 27 on interventions that were not considered in the original version. Interventions included amiodarone, beta-blockers, sotalol, magnesium, atrial pacing and posterior pericardiotomy. Each of the studied interventions significantly reduced the rate of post-operative atrial fibrillation after cardiac surgery compared with a control. Beta-blockers (odds ratio (OR) 0.33; 95% confidence interval) CI 0.26 to 0.43; I(2) = 55%) and sotalol (OR 0.34; 95% CI 0.26 to 0.43; I(2) = 3%) appear to have similar efficacy while magnesium's efficacy (OR 0.55; 95% CI 0.41 to 0.73; I(2) = 51%) may be slightly less. Amiodarone (OR 0.43; 95% CI 0.34 to 0.54; I(2) = 63%), atrial pacing (OR 0.47; 95% CI 0.36 to 0.61; I(2) = 50%) and posterior pericardiotomy (OR 0.35; 95% CI 0.18 to 0.67; I(2) = 66%) were all found to be effective. Prophylactic intervention decreased the hospital length of stay by approximately two-thirds of a day and decreased the cost of hospital treatment by roughly $1250 US. Intervention was also found to reduce the odds of post-operative stroke, though this reduction did not reach statistical significance (OR 0.69; 95% CI 0.47 to 1.01; I(2) = 0%). No significant effect on all-cause or cardiovascular mortality was demonstrated.

AUTHORS' CONCLUSIONS

Prophylaxis to prevent atrial fibrillation after cardiac surgery with any of the studied pharmacological or non-pharmacological interventions may be favored because of its reduction in the rate of atrial fibrillation, decrease in the length of stay and cost of hospital treatment and a possible decrease in the rate of stroke. However, this review is limited by the quality of the available data and heterogeneity between the included studies. Selection of appropriate interventions may depend on the individual patient situation and should take into consideration adverse effects and the cost associated with each approach.

Tocolytic therapy for acute preterm labor

The pathophysiology leading to preterm labor is not well understood and often multifactorial; initiating factors include intrauterine infection, inflammation, ischemia, overdistension, and hemorrhage. Given these different potential causes, directing therapy for preterm labor has been difficult and suboptimal. To date, no single drug has been identified as successful in treating all of the underlying mechanisms leading to preterm labor. In addition, the methodology of many of the tocolytic studies is limited by lack of sufficient patient numbers, lack of comparison with a placebo, and inconsistent use of glucocorticoids. The limitations in these individual studies make it difficult to evaluate the efficacy of a single tocolytic by meta-analysis. Despite these limitations, the goals for tocolysis for preterm labor are clear: To complete a course of glucocorticoids and secure the appropriate level of neonatal care for the fetus in the event of preterm delivery. The literature demonstrates that many tocolytic agents inhibit uterine contractility. The decision as to which tocolytic agent should be used as first-line therapy for a patient is based on multiple factors, including gestational age, the patient’s medical history, common and severe side effects, and a patient’s response to therapy. In a patient at less than 32 weeks gestation, indomethacin may be a reasonable first choice based on its efficacy, ease of administration, and minimal side effects. Concurrent administration of magnesium for neuroprotection may be given. At 32 to 34 weeks, nifedipine may be a reasonable first choice because it does not carry the fetal risks of indomethacin at these later gestational ages, is easy to administer, and has limited side effects relative to beta-mimetics. In an effort to review a commonly faced obstetrical complication, this article has provided a summary of the most commonly used tocolytics, their mechanisms of action, side effects, and clinical data regarding their efficacy.

[Place of magnesium salts in the treatment of cardiovascular disease]

The article examines the role of magnesium in the metabolism and the pathogenesis of common cardiovascular diseases, and provides research data on the use of magnesium salts as adjunctive therapy of these diseases.

[The effect of nitrates on the outcome of acute experimental ischemic stroke]

Effects of nitrates NaNO(3), KNO(3), Mg(NO(3)) 2 on animals (Wistar rats) were studied on the basis of the experimental model of ischemic stroke induced by the occlusion of two carotid arteries. The animals were divided into two groups: the main group (n=60) and the control group (n=30). Three series of experiments were conducted. In each experiment, the rats of the main group were treated with one of nitrates and the control group was treated with physiological solution. It has been shown that nitrates exert either positive or negative effect depending on the cation type, nitrate concentration and the duration of their action on the dynamics of neurologic disturbances. Conditions of the development of neuroprotective effect of nitrates are discussed.

[Prevention of postoperative hyperalgesia]

Three types of hyperalgesia can occur during the postoperative period: primary hyperalgesia, which disappears with wound healing, secondary or central hyperalgesia, which can lead to chronic pain, and opiate-induced hyperalgesia. Different drugs, most of which are NMDA receptors antagonists, are used to decrease or prevent the risk of central or opiate-induced hyperalgesia. However, it is difficult to determine whether they are really effective and at which dosage: the results of most published studies are difficult to interpret because of methodological problems. The two most frequent of those are: absence of objective measurement of secondary hyperalgesia and difficulties targeting an at risk population.

[Pharmacotherapy for preventing calcium containing stone formation]

Many urinary tract stones consist of calcium, and has high relapse rate. Accordingly, it is very important to prevent calcium-containing stone formation. This paper describes about effects and mechanisms for Xanthine oxidase inhibitor, citrate formulation, magnesium formulation, thiazides, vitamin B(6), extract of Quercus salicina Blume and chorei-to (medical herb) . Recent new drugs and the elucidation of new metabolic pathways may lead to the development of prevention of urolithiasis.

Comparison of magnesium-enriched hydroxyapatite and porcine bone in human extraction socket healing: a histologic and histomorphometric evaluation

PURPOSE

Different graft materials have been proposed to minimize the reduction in ridge volume after tooth extraction. The aim of the present study was to compare the use of synthetic magnesium-enriched hydroxyapatite (MHA) with porcine bone (PB) grafts in fresh sockets by histologic and histomorphometric analyses.

MATERIALS AND METHODS

Forty-five fresh extraction sockets were selected in 15 patients. A split-mouth design was used: 15 sockets received MHA in one side of the jaw (MHA group), 15 sockets on the other side received PB (PB group), and 15 random unfilled sockets were considered the control group. Four months after surgery, cylindric bone specimens were harvested for histologic and histomorphometric analyses.

RESULTS

Histologic examinations revealed an absence of inflammatory cells, bone formation in all treated sites, and the presence of biomaterial particles and connective tissue. Mean vital bone measurements for the MHA, PB, and control groups were 36.5% ± 2.6%, 38.0% ± 16.2%, and 30.3% ± 4.8%, respectively. Statistically significant differences were found between the MHA and control groups and between the PB and control groups; differences between the MHA and PB groups were not significant. Connective tissue percentages averaged 33.3% ± 1.5% for the MHA group, 25.3% ± 9.4% for the PB group, and 58.3% ± 7.1% for the control group. Statistically significant differences were found between all groups. Residual graft material occupied 32.2% ± 3.2% of the MHA-grafted sites and 36.6% ± 4.8% of the PB sites. This difference was not statistically significant.

CONCLUSIONS

Within the limits of this study, histologic examination showed the same biologic behavior in bone formation and resorption processes for the two examined biomaterials.

Abrasion, polishing, and stain removal characteristics of various commercial dentifrices in vitro

OBJECTIVE

To evaluate, using conventional in vitro procedures, the abrasivity, enamel polishing properties, and stain removal effectiveness of various commercial dentifrices that have a variety of compositions and are marketed for cleaning, whitening, and/or polishing capabilities, and to examine their relationships between stain removal and abrasivity.

METHODS

The Relative Dentin Abrasivity (RDA) method was used to measure abrasivity, and the Pellicle Cleaning Ratio (PCR) procedure was used to evaluate stain removal performance. A Cleaning Efficiency Index (CEI) was calculated using the RDA and PCR values. Enamel polish was determined on bovine enamel specimens using a reflectometer. All treatments were performed on a V-8 cross-brushing machine using aqueous dentifrice slurries and standard nylon-bristle toothbrushes. A total of 26 dentifrices, purchased at retail, were tested against the American Dental Association (ADA) calcium pyrophosphate reference standard.

RESULTS

All dentifrices removed extrinsic stain and produced some dentin abrasion, but scores ranged widely between products (from 36 to 269 for RDA and from 25 to 138 for PCR). The majority of dentifrices contained hydrated silicas, and those with high PCR scores often, but not always, had higher RDA values. Products containing other abrasives (e.g., dicalcium phosphate, sodium bicarbonate, and calcium carbonate) generally had lower RDA values and usually lower PCR scores. There were exceptions (e.g., refined kaolin clay) that had high PCR scores and low RDA values, resulting in higher CEI values. Similarly, brushing with all dentifrices significantly increased reflectance readings of acid-dulled teeth, but polish scores also were highly variable among products (ranging from 38 to 97). The polish scores of dentifrices containing hydrated silica varied extensively (ranging from 38 to 80), and the scores of products containing other abrasives fell within this same range, except for dentifrices containing either Fuller's earth (86) or kaolin (97).

CONCLUSION

With only a few exceptions, dentifrices marketed as "whitening" products were generally more abrasive to dentin, especially for those containing silicas. Similarly, aside from two non-silica products, those dentifrices advertised for polishing ability generally were no more effective than other products. The relationship between stain-removal ability and abrasivity of dentifrices was not necessarily direct.

Magnesium maintenance therapy for preventing preterm birth after threatened preterm labour

BACKGROUND

Magnesium maintenance therapy is one of the types of tocolytic therapy used after an episode of threatened preterm labour (usually treated with an initial dose of tocolytic therapy) in an attempt to prevent the onset of further preterm contractions.

OBJECTIVES

To assess whether magnesium maintenance therapy is effective in preventing preterm birth after the initial threatened preterm labour is arrested.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (May 2010).

SELECTION CRITERIA

Randomised controlled trials of magnesium therapy given to women after threatened preterm labour.

DATA COLLECTION AND ANALYSIS

The review authors independently assessed the studies for inclusion, assessed risk of bias and carried out data extraction. We checked data entry.

MAIN RESULTS

We included four trials, which recruited 422 women. Three trials had high risk of bias and none included any long-term follow up of infants. No differences in the incidence of preterm birth or perinatal mortality were seen when magnesium maintenance therapy was compared with placebo or no treatment; or alternative therapies (ritodrine or terbutaline). The risk ratio (RR) for preterm birth (less than 37 weeks) for magnesium compared with placebo or no treatment was 1.05, 95% confidence interval (CI) 0.80 to 1.40 (two trials, 99 women); and 0.99, 95% CI 0.57 to 1.72 (2 trials, 100 women) for magnesium compared with alternative therapies. The RR for perinatal mortality for magnesium compared with placebo or no treatment was 5.00, 95% CI 0.25 to 99.16 (one trial, 50 infants) and also compared with alternative treatments, was 5.00, 95% CI 0.25 to 99.16 (one trial, 50 infants). Women taking magnesium preparations were less likely to report palpitations or tachycardia than women receiving alternative therapies (RR 0.26, 95% CI 0.13 to 0.52, three trials, 237 women) but were much more likely to experience diarrhoea (RR 7.66, 95% CI 2.18 to 26.98, three trials, 237 women).

AUTHORS' CONCLUSIONS

There is not enough evidence to show any difference between magnesium maintenance therapy compared with either placebo or no treatment, or alternative therapies (ritodrine or terbutaline) in preventing preterm birth after an episode of threatened preterm labour.

N-acetylcysteine and magnesium improve biochemical abnormalities associated with myocardial ischaemic reperfusion in South Indian patients undergoing coronary artery bypass grafting: a comparative analysis

INTRODUCTION

The clinical presentation of ischaemic reperfusion in postoperative patients correlates with oxidative stress. The limited clinical success of anti-ischaemic reperfusion agents has prompted a comparison of the efficacy of N-acetylcysteine (NAC) and magnesium (Mg) in South Indian patients undergoing coronary artery bypass grafting (CABG).

METHODS

In Clinical Trial I, 52 South Indian patients who had undergone CABG surgery (with intraoperative Mg supplementation) and 40 controls (without Mg supplementation) were selected and matched. The control patients underwent the same protocol without Mg. In Clinical Trial II, the study population consisted of 50 patients, where 25 patients received NAC just before the release of the aortic cross clamp. In the NAC untreated group, dextrose solution was administered at the same time as the placebo. Six blood samples were taken at different times during the cardiac surgery and the antioxidant enzymes, ATPase and cardiac markers from the coronary sinus blood samples were analysed.

RESULTS

Increased blood lipid peroxidation was observed in patients who were not treated with Mg/NAC. The administration of Mg/NAC just before the release of the aortic cross clamp reduced the lipid peroxidation significantly (p-value is less than 0.05). The above observations were supported by the antioxidant enzyme levels. Significant improvements to the erythrocyte ATPase and cardiac markers in patients treated with Mg/NAC correlated with a reduction in postoperative abnormalities. Based on the biochemical status of the patients, Mg was shown to mediate better recovery from postoperative changes.

CONCLUSION

NAC and Mg decreased pump-induced oxidative stress during cardiopulmonary bypass (CPB), suggesting that it could be a novel therapy for assisting in the prevention of CPB-induced oxidative stress.

[Effects of mangesium salts and their combinations with vitamin B6 on oxalates crystalluria in rats fed with pyridoxine-deficient diet]

We studied the effects of oral magnesium (Mg) salts either alone or in combination with pyridoxine hydrochloride in rats on pyridoxine-deficient diet. Fifty-four male rats were randomized into two groups and were fed either a standard diet or a pyridoxine-deficient diet for 3 weeks. A significant rise of the EGOT index ( > 1.5), oxaluria (from 74.8 +/- 5.2 to 117.9 +/- 12.3 mcM/l, p = 0.035), and crystalluria in rats fed with pyridoxine deficient diet were revealed. Oral Mg chloride, Mg L-aspartate either alone or in combination with pyridoxine in comparison with magnesium sulfate, magne B6 (Mg lactate with pyridoxine) and pyridoxine alone were administered (50 mg of magnesium and/or 5 mg of pyridoxine per kg body weight). Magnesium salts in combination with pyridoxine lowered an oxalate level and crystalluria whereas magnesium salts alone reduced only crystalluria. Antilithis effects of Mg L-aspartate and Mg chloride in combination with pyridoxine were comparable with those observed in magne B6 or pyridoxine treatment and were significantly higher than in magnesium sulfate treatment.

Magnesium for acute traumatic brain injury

BACKGROUND

Acute traumatic brain injury is a leading cause of death and disability in young adults. Numerous pharmacological and non-pharmacological tools have been investigated and considered as potential mechanisms for improving neurological outcome. Magnesium has been considered as one of these potential therapeutic tools because of its activity on NMDA-receptors, calcium channels and neuron membranes. Animal studies have indicated a beneficial effect of magnesium on outcome after brain injury, but its efficacy in humans is unknown.

OBJECTIVES

To quantify the effect of magnesium administration on mortality and morbidity in patients with acute traumatic brain injury.

SEARCH STRATEGY

We searched the Cochrane Injuries Group's specialised register, Cochrane Central Register of Controlled Trials, CENTRAL (The Cochrane Library issue 2, 2008), MEDLINE (and PubMed to 28 May, 2008: last 60 days), EMBASE, National Research Register, Current Controlled Trials, SIGLE, LILACS, and Zetoc. Searches were initially conducted in July 2005. The latest search was conducted in May 2008.

SELECTION CRITERIA

We included all randomized controlled trials comparing any magnesium salt with no magnesium or with placebo, in patients following acute traumatic brain injury.

DATA COLLECTION AND ANALYSIS

Two authors independently screened search results and assessed the full texts of potentially relevant studies for inclusion. Data were extracted and methodological quality was examined.

MAIN RESULTS

Four studies met the inclusion criteria; one of which is an ongoing study. Data from three studies were included in the analysis. Data on mortality were only available in one study; RR 1.48 [1.00, 2.19], Test for overall effect: Z = 1.96 (P = 0.05). Glasgow Outcome Score at six months was described in the three studies. The Mean Difference = 0.02 (95% CI -0.38 to 0.041), Test for overall effect: Z = 0.08 (P = 0.94).

AUTHORS' CONCLUSIONS

There is currently no evidence to support the use of magnesium salts in patients with acute traumatic brain injury.

Antimotility agents for chronic diarrhoea in people with HIV/AIDS

BACKGROUND

AIDS-related diarrhoea is a common cause of morbidity and mortality in HIV positive individuals, especially in the sub-Saharan Africa where 70% of deaths from HIV occur. It often compromises quality of life both in those receiving antiretroviral therapy (ART) and the ART naive. Empirical antidiarrhoeal treatment may be required in about 50% of cases which are non-pathogenic or idiopathic and in cases resulting from antiretroviral therapy. Antimotility agents (Loperamide, Diphenoxylate, Codeine) and adsorbents (Bismuth Subsalicylate, Kaolin/Pectin, Attapulgite) are readily available, and have been found to be useful in this condition and so, are often used. Antimotilitics are opioids, decreasing stool output by reducing bowel activity thereby increasing fecal transit time in the gut, promoting fluid and electrolyte retention while adsorbents act by binding to fluids, toxins and other substances to improve stool consistency and eliminate the toxins. Due to its potential impact on the management of chronic diarrhoea in persons with HIV/AIDS, we reviewed the effectiveness of antimotility agents in controlling chronic diarrhoea in immunocompromised states caused by HIV/AIDS.

OBJECTIVES

To assess the effectiveness of antimotility agents in controlling chronic diarrhoea in people with HIV/AIDS.

SEARCH STRATEGY

We searched Medline, EMBASE, the Cochrane Controlled Trials Register, the Cochrane HIV/AIDS Register and AIDSearch databases in November 2006. We also contacted WHO, CDC, pharmaceutical companies and experts in the field for information on previous or on-going trials and checked reference list from retrieved studies, irrespective of language and publication status.

SELECTION CRITERIA

Randomised controlled trials comparing an antimotility agent or an adsorbent with another antimotility agent, placebo, an adsorbent or no treatment in children and adults diagnosed with HIV and presenting with diarrhoea of three or more weeks duration.

DATA COLLECTION AND ANALYSIS

Two authors independently undertook study selection and examined full articles of potentially eligible studies.

MAIN RESULTS

One trial was found assessing the use of an adsorbent (attapulgite) compared to a placebo for chronic diarrhoea in people with HIV/AIDS. It included 91 adults (Aged 18 to 60), diagnosed with AIDS and experiencing diarrhoea for at least 7 days. There was no evidence that attapulgite is superior to placebo in controlling diarrhoea by reducing stool frequency and normalising stool consistency on days 1 (0.34 (95% CI 0.01 - 8.15)), 3 (1.35 (95% CI 0.51 - 3.62)) and 5 (1.74 (95% CI 0.89 - 3.38)). This was a small trial and may not have had enough power to show evidence of effects. Five deaths were reported which was not classified according to the arms of the study.Studies assessing the use of antimotility agents were not found.

AUTHORS' CONCLUSIONS

This review highlights the absence of evidence for the use of antimotility agents and adsorbents in controlling diarrhoea in people with HIV/AIDS. While no trials assessing the use of Antimotilitics were found, the retrieved study showed that attapulgite was not better than placebo in controlling diarrhoea in HIV/AIDS patients . For optimum patient care, these agents can still be used, with greater emphasis placed on adjunct therapies like massive fluid replacement while evidence for practice is awaited from further studies and reviews.

[Depression-like and anxiety-related behaviour of rats fed with magnesium-deficient diet]

The aims of this study were to estimate of psychomotor activity, emotional status and magnesium (Mg) content in blood of rats fed with Mg-deficient diet for 49 days; and to find out whether the combination of vitamin B6 with Mg will reveal antidepressant- and anxiolytic-like activity and reduce the length of the treatment needed to recover rats from Mg-deficient condition. To induce hypomagnesemia, seventy-nine rats were placed on a Mg-deficient diet (Mg content < or = 15 mg/kg) and demineralized water for 7 weeks. Eight control rats were fed a basal control diet. On the forty-ninth day of Mg-deficient diet, rats were treated one of the six supplementations: Mg L-aspartate alone and in combination with pyridoxine, MgCl2 x 6H2O alone and in combination with pyridoxine, Magne B6 (Mg lactate with pyridoxine) and Mg sulfate (50 mg Mg and 5 mg vitamin B6 per kg). In our study Mg-deficiency was associated with depleted intraerythrocytic (0.748 +/- 0.036 vs. 1.83 +/- 0.026 mmol/l, p < 0.001) and plasma (0.567 +/- 0.029 vs. 1.20 +/- 0.030 mmol/l, p < 0.001) Mg level compared to control rats. It was shown Mg deficiency resulted in depression-like and anxiety-related behavior in rats. Open field test result in rats including locomotor activity (number of crossed squares) and vertical activity (number of standing on hind paws), number of visiting in central squares were decreased significantly. In the elevated plus maze test, the number of visiting open arms (by 63.6%) and residence time (by 78.5%) of rats were significantly less as compared with the control group. In the forced swimming test, time immobile was significantly increased (by 70.2%) and time of swimming was decreased (by 15%) compared to control. Mg salts alone and in combination with vitamin B6 administered to Mg-deficient rats increased the Mg level in plasma and erythrocytes. Furthermore, this increase was in relation to vitamin B6 given to the animal. It was established, that the application of Mg L-aspartate and MgCl2 x 6H2O in combinations with pyridoxine led to correction of behavioural disturbances of Mg-deficient animals. Antidepressant- and anxiolytic-like activity of studied salts was comparable with those observed in Magne B6 treatment and significantly higher than in Mg sulfate treatment.

Potassium, magnesium, and calcium: their role in both the cause and treatment of hypertension

Despite advances in the prevention and treatment of hypertension over the past decade, hypertension remains an important public health challenge. Recent efforts to reduce the prevalence of hypertension have focused on nonpharmacologic means, specifically diet. An increased intake of minerals such as potassium, magnesium, and calcium by dietary means has been shown in some but not all studies to reduce blood pressure in patients with hypertension. This review will discuss the roles of potassium, magnesium, and calcium in the prevention and treatment of essential hypertension with specific emphasis on clinical trial evidence, mechanism of action, and recommendations for dietary intake of these minerals. A high intake of these minerals through increased consumption of fruits and vegetables may improve blood pressure levels and reduce coronary heart disease and stroke.

[The use of Magne B6 in order to increase compensatory-adaptive possibilities in youths with primary mitral valve prolapse]

The aim of the study--to estimate the effect of therapy with Magne 6 on the indices of cardiac hemodynamics, tolerance to physical load, activity of antioxidant protection enzymes and grade of hypoxia in youths with 1 grade mitral valve prolapse (MVP) without regurgitation. In 73 cases with impaired compensatory adaptive possibilities the extent of main syndromes of autonomic dystonia and state of cardiac hemodynamic indices were evaluated. The activity of catalase (C), glutathione reductase (GR), superoxide dismutase (SOD), lactate (L) and pyruvate (P) level were detected in red blood cells, the coefficient lactate/pyruvate (L/P) was been calculated according to the standard method. In the study the high-grade of autonomic dystonia (36.6 +/- 2.1 scores) was been revealed. The number of scores in the control group is 10.8 +/- 1.8. There was found the confident increase of stroke by 37.18%, cardiac output by 24%, stroke index--by 38.45% and cardiac index--by 43.06% in comparison with healthy persons (a < 0.05). The time of cycle ergometer load was significantly lower than in reference group 20.22% (a < 0.05). The red blood cells levels of PVK and L were correspondingly 95.4% and 51.4% higher than in control (p < 0.05). The L/P ratio was 22.5% in excess of the value in reference group (p < 0.05). C activity was 4.59 times less, SOD and GR activity were correspondingly 6.23 and 1.85 times (p < 0.05) as mush, than in healthy persons. Associated with Magne 6 therapy for a month the improvement in indices of cardiac hemodynamics, rising of tolerance to physical load, the fall in GR activity and decrease of hypoxia were been noted. Magne 6 may be used for magnifying of compensatory--adaptive possibilities in youths with 6 MVP.

[Magnesium deficiency in an endocrinologist's practice]

The review concerning a value of magnesium in an organism in healthy persons and cases with endocrine disorders is presented. The causes of magnesium-deficient conditions in cases with type 1 and type 2 diabetes, thyrotoxic goiter, hypothyroidism and obesity were analyzed. Participation of magnesium in secretion of parathormone and a control of calcium exchange is shown. The clinical semiology of hypomagnesemia seems to be nonspecific and manifold, and, therefore, as a rule, in most of endocrine patients magnesium deficiency remains to be undiagnosed. Questions on preventive measures and management of treatment magnesium-deficient conditions are considered.

[The role of alimentary magnesium deficiency in development of nephrolithiasis and its correction with magnesium salts in rats]

Aims of our work were to appraise the quantity and nature of renal calcifications and mineral metabolism in the magnesium-deficient rats; and to find out whether the combination of pyridoxine with Mg L-aspartate or Mg chloride will reduce the length of the treatment needed to recover rats from magnesium deficient condition and urolithiasis state. To induce hypomagnesemia, fifty rats were placed on a magnesium-deficient diet (magnesium content < or = 15 mg/kg) and demineralized water for 10 weeks. On the forty-ninth day of magnesium-deficient diet, rats were treated one of the six supplementations: MgCl2, Mg-L-Asp or their combinations with pyridoxine hydrochloride, magnesium sulfate, magne B6.

The use of esmolol and magnesium to prevent haemodynamic responses to extubation after coronary artery grafting

BACKGROUND AND OBJECTIVE

The haemodynamic responses during extubation can cause complications after open-heart surgery. In this study, we aimed to examine the effect of esmolol and magnesium before extubation on these haemodynamic responses.

METHODS

Following the approval of local Ethics Committee, 120 patients having coronary artery bypass grafting with extubation in the intensive care unit were included in the study. Patients were allocated to receive esmolol 1 mg kg-1 (group I, n = 40), magnesium 30 mg kg-1 (Group II, n = 40) or normal saline (Group III, n = 40). Study medication was administered as a 20-min infusion in a volume of 20 mL. Patients were extubated just after termination of the infusion. Heart rate, blood pressure and central venous pressure were recorded prior to drug administration, before extubation, during extubation and 1 min after extubation.

RESULTS

Heart rate was lower in Group I than in Groups II (P < 0.05) and III (P < 0.001) and lower in Group II than in Group III (P < 0.05) during extubation. It was also lower in Group I than in Group III (P < 0.05) after extubation. Systolic blood pressure was lower in Group I than in Groups II and III (P < 0.001) during extubation. Diastolic blood pressure was higher in Group III than in Groups I and II during extubation (P < 0.001) and after extubation (P < 0.05). Mean arterial pressure was lower in Group I than in Groups II and III (P < 0.001) during extubation, lower in Group II than in Group III (P < 0.05) during extubation and lower in Group I than in Group III (P < 0.05) after extubation.

CONCLUSION

We found that using esmolol before extubation following coronary artery bypass graft surgery prevents undesirable haemodynamic responses while magnesium reduces undesirable haemodynamic responses but does not prevent them.

Early restenosis following biodegradable stent implantation in an aortopulmonary collateral of a patient with pulmonary atresia and hypoplastic pulmonary arteries

Traditionally, the implantation of stents in young children with small blood vessels has been avoided as the presence of a metallic or fixed stent structure limits the ability to further dilate the stent with vessel growth. Pulmonary atresia with ventricular septal defect and hypoplastic pulmonary arteries represents one such cohort where the placement of fixed nondegradable stents has been difficult. We report a 2-month-old girl with pulmonary atresia, VSD, and multiple aorto-pulmonary collaterals with severely hypoplastic pulmonary arteries who underwent placement of a biodegradable magnesium stent within a stenotic aorto-pulmonary collateral. Although there was an initial significant increase in vessel diameter, significant restenosis occurred 4 months after stent placement. This to our knowledge represents the first case of the use of biodegradable stents in a child with severely hypoplastic pulmonary arteries. Although further refinements in stent technology are required, this development will hopefully usher in a new era of potential intervention in children previously deemed unsuitable for stent placement.

Advances in the management of organophosphate poisoning

Organophosphate (OP) poisoning is commonly encountered in agricultural communities. The mainstay of therapy in OP poisoning is the use of atropine. However, several other therapies have been evaluated. Although oxime has been the most studied antidote, results in humans have been disappointing and limited by the lack of well-designed, prospective, randomised controlled trials. The key factor in determining outcomes in OP poisoning appears to be the timing of antidote administration. Other adjuvants, such as magnesium, fresh frozen plasma and haemoperfusion appear promising, and need to be explored further. A multi-faceted approach may be the answer to improving outcomes in OP poisoning. This review evaluates the advances in OP management over the last 20 years.

Effects of a magnesium adhesive cement on bone stability and healing following a metatarsal osteotomy in horses

OBJECTIVE

To compare biodegradable magnesium phosphate cement (Mg-cement), calcium phosphate cement (Ca-cement), and no cement on bone repair, biocompatibility, and bone adhesive characteristics in vivo in horses.

ANIMALS

8 clinically normal adult horses.

PROCEDURES

Triangular fragments (1-cm-long arms) were created by Y-shaped osteotomy of the second and fourth metatarsal bones (MTII and MTIV, respectively). Fragments were replaced in pairs to compare Mg-cement (MTII, n = 8; MTIV, 8) with Ca-cement (MTIV, 8) or with no cement (MTII, 8). Clinical and radiographic evaluations were performed for 7 weeks, at which time osteotomy sites were harvested for computed tomographic measurement of bone density and callus amount, 3-point mechanical testing, and histologic evaluation of healing pattern and biodegradation.

RESULTS

All horses tolerated the procedure without clinical problems. Radiographically, Mg-cement secured fragments significantly closer to parent bone, compared with Ca-cement or no treatment. Callus amount and bone remodeling and healing were significantly greater with Mg-cement, compared with Ca-cement or no cement. Biomechanical testing results and callus density among treatments were not significantly different. Significantly greater woven bone was observed adjacent to the Mg-cement without foreign body reaction, compared with Ca-cement or no cement. The Mg-cement was not fully degraded and was still adhered to the fragment.

CONCLUSIONS AND CLINICAL RELEVANCE

Both bone cements were biocompatible in horses, and Mg-cement may assist fracture repair by osteogenesis and fragment stabilization. Further studies are warranted on other applications and to define degradation characteristics.

Reduction of Renal Stone Risk by Potassium-Magnesium Citrate During 5 Weeks of Bed Rest

PURPOSE

Exposure to the microgravity environment of space increases the risk of kidney stone formation, particularly for calcium oxalate and uric acid stones. This study was performed to evaluate the efficacy of potassium alkali as potassium-magnesium citrate in reducing renal stone risk and bone turnover.

MATERIALS AND METHODS

This study was performed as a double-blind, placebo controlled trial. We studied 20 normocalciuric subjects randomized to either placebo or potassium-magnesium citrate (42 mEq potassium, 21 mEq magnesium, 63 mEq citrate per day) before and during 5 weeks of strict bed rest. The study was performed in the General Clinical Research Center and under a controlled dietary regimen composed of 100 mEq of sodium, 800 mg of calcium, 0.8 gm/kg animal protein and 2,200 kcal per day. Two 24-hour urine collections were obtained under oil each week for assessment of stone risk parameters and relative saturation of calcium oxalate, brushite and undissociated uric acid. Blood was also collected for determination of serum immunoreactive parathyroid hormone and vitamin D metabolites.

RESULTS

Bed rest promoted a rapid increase in urinary calcium excretion of approximately 50 mg per day in both groups. Despite this increase subjects treated with potassium-magnesium citrate demonstrated significant decreases in the relative saturation of calcium oxalate and in the concentration of undissociated uric acid compared to placebo. Immunoreactive parathyroid hormone, serum 1,25-dihydroxyvitamin D and intestinal calcium absorption all decreased in both groups with no difference in response between the 2 treatment arms.

CONCLUSIONS

Provision of alkali as potassium-magnesium citrate is an effective countermeasure for the increased risk of renal stone disease associated with immobilization. Despite an increase in urine calcium concentration, the relative saturation of calcium oxalate decreased due to citrate chelation of calcium and the concentration of undissociated uric acid decreased due to the significant increase in urine pH.

Lidocaine-magnesium blood cardioplegia was equivalent to potassium blood cardioplegia in left ventricular function of canine heart

This study evaluated the effects of lidocaine-magnesium blood cardioplegia on left ventricular function compared with potassium blood cardioplegia. Crystalloid cardioplegia which contains lidocaine has been reported but blood cardioplegia is rare. Thirteen dogs received 60 min of global ischemia under hypothermic cardioplumonary bypass (30 degrees C). Potassium blood cardioplegia was administered every 20 min in group A (n=6), and lidocaine-magnesium blood cardioplegia in group B (n=7). We compared the ratio of Emax obtained during IVC occlusion at pre- and post-global ischemia (%Emax) and LVSW (%LVSV). Cardiac function was evaluated prior to CPB and 60 min after reperfusion. There was no difference in time required for cardiac arrest between the two groups (group A: 78+/-3 s, group B: 89+/-9 s). Percentage maximal elastance was significantly better in group B (group A: 63+/-3%, group B: 76+/-4%, P<0.05). Percentage tissue water content of the myocardium after CPB was significantly lower in group B (group A: 82.3+/-4%, group B: 75.5+/-2%, P<0.05). Lidocaine-magnesium blood cardioplegia was equivalent to potassium blood cardioplegia in systolic left ventricular function and reduced myocardial edema in canine heart.

Magnesium for acute traumatic brain injury

BACKGROUND

Acute traumatic brain injury is a leading cause of death and disability in young adults. Magnesium had been considered as a potential therapeutic tool because of its activity on NMDA-receptors, calcium channels and neuron membranes. Animals studies have indicated a beneficial effect of magnesium on outcome after brain injury, but its efficacy in humans is unknown.

OBJECTIVES

To quantify the effect of magnesium administration on mortality and morbidity in patients with acute traumatic brain injury.

SEARCH STRATEGY

We searched the Cochrane Injuries Group's specialised register, Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, National Research Register, Current Controlled Trials, SIGLE, LILACS, Zetoc. The searches were conducted in July 2005.

SELECTION CRITERIA

We included all randomized controlled trials comparing any magnesium salt with no magnesium or with placebo, in patients following acute traumatic brain injury.

DATA COLLECTION AND ANALYSIS

Two authors independently screened search results and assessed the full texts of potentially relevant studies for inclusion. Data were extracted and methodological quality was examined.

MAIN RESULTS

Three studies met the inclusion criteria, one of which is an ongoing study. Two studies were included in the analysis. No data on mortality were available. For Glasgow Outcome Score at six months the pooled WMD = 0.55 (95% CI -0.15 to 1.26), P = 0.12.

AUTHORS' CONCLUSIONS

There is currently no evidence to support the use of magnesium salts in patients with acute traumatic brain injury.

[Experimental study on magnesium phosphate cement in fracture treatment]

OBJECTIVE

To investigate the effect of magnesium phosphate cement (MPC) to fix fractures.

METHODS

In vitro: fifty-four pairs of fresh pig femoral heads were made 1 cm2 fracture and divided into 6 groups (n=9 pairs ). MPC was used to agglutinate fracture of femoral heads at 100% humidity and at 25 degrees C, 37 degrees C respectively. At 30 minutes, 2 and 24 hours after agglutination, the biomechanical strength was measured. In vivo: the tibia plateau fracture models on both sides of 24 rabbits were made, one side was fixed with "L" shaped plate, and the other side was fixed with MPC. Then the effect of treatment was investigated by macrography, micrography, radiography and the In vitro: the adhesive ability of changes of serum electrolyte levels at 3 days, 3, 6 and 9 weeks after operation.

RESULTS

MPC was strong. At 24 hours after MPC agglutination, the average tensile strength was 117.16 +/- 23.29 N/cm2. In vivo: after 6 weeks of fixation, the X-ray results showed that all rabbits' tibia plateau fractures were healed without displacement, and MPC was absorbed gradually. The changes of serum electrolyte levels were very minimal. The macrography observation showed that reduction of fracture were good at 3 days after operation, partial MPC remained in fracture end at 3 weeks, fracture line disappeared at 6 weeks and good remodeling was achieved at 9 weeks after operation in the experimental group. The micrography observation showed that the interface between bone and MPC was distinct at 3 days, MPC was degraded gradually and trabeculae began to grow into MPC at 3 weeks, and almost all MPC was degraded at 6 and 9 weeks of operation.

CONCLUSION

MPC is a promising biomaterial, and might potentially be used for fracture treatment.

Effect of Lomodex-MgSO(4) in the prevention of reperfusion injury following unilateral testicular torsion: an experimental study in rats

Fertility in patients treated for unilateral testicular torsion has been shown to be significantly reduced in all the reported series to date, implying that the present-day treatment requires further refinement in the form of adjunct pharmacotherapeutic intervention (Lomodex and MgSO(4)) in addition to scrotal exploration. Prepubertal Holtzman strain rats (35 days old) were used for our study. Two sets were formed with six groups of rats in each set. Rats were treated as follows: group 1, sham-operated group; group 2, torsion (4 h); group 3, torsion + detorsion (1 h); group 4, torsion + ATP-MgCl(2) + detorsion; group 5, torsion + Lomodex-MgSO(4) + detorsion; group 6, torsion + normal saline + detorsion. Whereas the first set of animals was sacrificed immediately at the end of experiment, animals in set 2 were sacrificed 8 weeks after the end of the experiment to look for the development of antisperm antibodies. Parameters studied were thiobarbituric acid reductase (TBAR) assay, histology of testicular tissue, and sperm agglutination test. Student's t-test was used for significance. With detorsion (149.95+/-30.68) there was a significant rise in the TBAR values (P<0.05) compared with torsion (57.39+/-14.47). Treatment with both Lomodex-MgSO(4) (40.74+/-6.39) and ATP-MgCl(2) (48.30+/-18.35) yielded TBAR levels comparable to those in the sham group (31.35+/-11.96). Similar injury was also seen on the contralateral testis, with detorsion (114.28+/-10.68) much more detrimental than torsion (40.59+/-15.02) and rescue seen following treatment with Lomodex-MgSO(4) (27.55+/-8.64) as well as ATP-MgCl(2) (38.61+/-12.23). Regarding th histology, with detorsion there was evidence of severe distortion of tubules, with almost all the tubules showing maturation arrest and a few tubules completely devoid of any germinal cells. Treatment with Lomodex-MgSO(4) as well as ATP-MgCl(2) showed preservation of tubular morphology. Our study failed to document the presence of agglutinating antibodies (antisperm antibodies) in any of the groups. Unilateral testicular torsion has bilateral effects and is a form of ischemia-reperfusion injury. Treatment of torsion by detorsion alone does not prevent testicular damage. The results of the present study show that administration of Lomodex + MgSO(4) prior to detorsion results in prolonged testicular salvage with a potential of subsequent improvement in semen quality and fertility and reduction in long-term morbidity. The presence of agglutinating antibodies could not be detected in the present study.

Magnesium in cardiovascular and other disorders

PURPOSE

The physiological role and metabolism of magnesium, the causes of magnesium deficiency, clinical data on the benefits of magnesium supplementation, and the management of magnesium deficiency are discussed.

SUMMARY

Magnesium is an often overlooked electrolyte that is essential to life. Magnesium plays a role in more than 300 enzymatic reactions and is critically involved in energy metabolism, glucose utilization, protein synthesis, fatty acid synthesis and breakdown, ATPase functions, and virtually all hormonal reactions. Magnesium is closely involved in maintaining cellular ionic balance through its association with sodium, potassium, and calcium. Deficiency of magnesium is becoming more common in the U.S. population and may be attributed to decreased dietary consumption and the use of diuretics; in the elderly, magnesium deficiency may be a consequence of reduced appetite, decreased mitochondrial respiratory activity, and increased myocardial collagen. Conditions that may be associated with magnesium deficiency include hypertension, congestive heart failure, arrhythmia, myocardial infarction, diabetes mellitus, and preeclampsia; in many of these, magnesium supplementation has been found beneficial in clinical studies. Supplementation should be considered for patients with risk factors for deficiency and should be instituted for patients showing symptoms of deficiency. In addition to instituting supplementation when appropriate, the clinician should identify and correct the underlying cause of the deficiency.

CONCLUSION

Magnesium deficiency may contribute to pathological processes. Clinicians should consider using magnesium supplementation to prevent deficiency in patients at risk and to treat deficiency when it occurs.