Calcium deprivation increases the palatability of calcium solutions in rats

Calcium-deprived rats have elevated intakes of CaCl2, other calcium salts, and some non-calcium compounds. We used taste reactivity to examine the effects of calcium deprivation on the palatability of CaCl2 and other solutions. Nine male Sprague-Dawley rats were calcium-deprived by maintenance on a low-calcium diet, and eight replete rats were used as controls. All rats were videotaped during intraoral infusion of the following solutions: 30 and 300 mM CaCl2, 30 mM calcium lactate, 100 and 600 mM NaCl, 30 mM MgCl2, 1 mM quinine.HCl, 2.5 mM sodium saccharin, and deionized water. We counted individual orofacial and somatic movements elicited by the infusions and used them to calculate total ingestive and aversive scores. Relative to controls, calcium-deprived rats gave a significantly larger number of tongue protrusions and had higher total ingestive scores for CaCl2, calcium lactate, NaCl, and MgCl2. Our results suggest that CaCl2, calcium lactate, NaCl, and MgCl2 taste more palatable to rats when they are calcium-deprived than replete, and this may be responsible for the increased intake of these solutions following calcium deprivation.

[Evaluation of the protective effect of magnesium on amikacin ototoxicity by electrophysiologic tests in guinea pigs]

OBJECTIVES

This experimental study was performed to evaluate the protective effect of magnesium on amikacin ototoxicity.

STUDY DESIGN

Twenty-seven guinea pigs (54 ears) with normal auropalpebral reflexes and otomicroscopic examination, auditory brain stem responses (ABR), and transient evoked otoacoustic emissions (TEOAE) were randomly divided into four groups to receive amikacin once 15 mg/kg daily (group 1 and 3) and twice 7.5 mg/kg daily (group 2 and 4) for seven days. Groups 3 and 4 were administered oral MgCl an hour after amikacin use at a dose of 39 mmol/l and 19.5 mmol/l, respectively, for seven days. Otomicroscopic examination, ABR and TEOAE measurements were repeated on the third, fifth, and seventh days.

RESULTS

Compared to group 1, decreases in TEOAE amplitudes and reproducibility and increases in ABR thresholds were significant in group 2 (p<0.05). However, in groups 3 and 4, TEOAE amplitudes remained unchanged, or even increased and the reproducibility of TEOAE responses and ABR thresholds showed no significant changes (p>0.05).

CONCLUSION

Our data show that oral magnesium may play a protective role on amikacin ototoxicity.

Manipulating the Dietary Cation-Anion Difference via Drenching to Early-Lactation Dairy Cows Grazing Pasture

Diets offered to grazing dairy cows can vary considerably in their dietary cation-anion difference (DCAD) and are often well in excess of what has been considered optimal. The effects of a range of DCAD on the health and production of pasture-based dairy cows in early lactation was examined in a randomized block design. Four groups of 8 cows were offered a generous allowance of pasture (45 +/- 6 kg/d of dry matter (DM) per cow) for 35 d and achieved mean pasture intakes of approximately 17 kg/d of DM per cow. Cows were drenched twice daily with varying combinations of mineral compounds to alter the DCAD. Dietary cation-anion difference ranged from +23 to +88 mEq/100 g of DM. A linear increase in blood pH and HCO(3)(-) concentration and blood base excess, and a curvilinear increase in the pH of urine with increasing DCAD indicated a nonrespiratory effect of DCAD on metabolic acid-base balance. Plasma concentrations of Mg, K, and Cl declined as DCAD increased, whereas Na concentration increased. Urinary excretion of Ca decreased linearly as DCAD increased, although the data suggest that the decline may be curvilinear. These results in conjunction with the increased concentrations of ionized Ca suggest that intestinal absorption of Ca or bone resorption, or both, increased as DCAD declined. Dry matter intake, as measured using indigestible markers, was not significantly affected by DCAD. However, the linear increase in the yield of linolenic acid, vaccenic acid, and cis-9, trans-11 conjugated linoleic acid in milk, as DCAD increased is consistent with a positive effect of DCAD on DM intake. Increasing DCAD did not significantly affect milk yield or milk protein, but the concentration and yield of milk fat linearly increased with increasing DCAD. The increased milk fat yield was predominantly a result of increased de novo synthesis in the mammary epithelial cells, although an increase in the yield of preformed fatty acids also occurred. Milk production results suggest that DCAD for optimal production on pasture diets may be higher than the +20 mEq/100 g of DM previously identified for total mixed rations.

Magnesium inhibits norepinephrine release by blocking N-type calcium channels at peripheral sympathetic nerve endings

Although Mg2+ contributes to blood pressure regulation partly in terms of vasodilator action, its sympatholytic effect may also play an important role to control blood pressure. Thus, in the present study, we investigated the effect of Mg2+ on sympathetic tone and blood pressure. We studied its actions on the blood pressure response to hydralazine, a direct vasodilator, in conscious spontaneously hypertensive rats (SHRs), and to electrical stimulation in the pithed Sprague-Dawley rat; catecholamine release by peripheral sympathetic nerve endings; and the N-type Ca2+ channels of cultured neural cells. Intravenous Mg2+ infusion (MgSO4: 3x10(-6) mol/kg body weight/min) induced the greater hypotensive response to hydralazine with attenuated reflex tachycardia in SHRs. In pithed rats, Mg2+ infusion significantly attenuated the blood pressure elevation (2+/-2 mm Hg versus 27+/-6 mm Hg, P<0.01) in response to spinal electrical stimulation. In the perfused mesenteric arteries system, norepinephrine release was significantly attenuated (51+/-2%, P<0.01) by high Mg2+ concentration solution (4.8 mmol/L) compared with normal Mg2+ solution (1.2 mmol/L). When we applied the perforated whole-cell patch clamp method to nerve growth factor-treated PC12 cells, Mg2+ blocked voltage-gated Ca2+ currents in a concentration-dependent manner. The majority of the voltage-gated Ca2+ currents were carried through N-type channels, followed by L-type channels. Mg2+ blocked both of these channels. These findings suggest that Mg2+ blocks mainly N-type Ca2+ channels at nerve endings, and thus inhibits norepinephrine release, which decreases blood pressure independent of its direct vasodilating action.

Magnesium therapy and recovery of function in experimental models of brain injury and neurodegenerative disease

The role of magnesium (Mg(2+)) in brain injury has been well established. The present paper reviews the use of Mg(2+) therapy to facilitate recovery of function in a focal model of brain injury. Specifically a summary of the ability of magnesium chloride (MgCl(2)) to induce recovery of chronic behavioral impairments and the establishment of MgCl(2)'s wide therapeutic window is presented. These results suggest that Mg(2+) therapy is effective in facilitating recovery of function and exhibits very robust and unique effects.

Magnesium in addition to sotalol does not influence the incidence of postoperative atrial tachyarrhythmias after coronary artery bypass surgery

OBJECTIVE

Postoperative atrial tachyarrhythmias (POATs) after coronary artery bypass grafting (CABG) are reported in 11% to 40% of patients. Several etiologic factors are mentioned. Prophylactic intervention with sotalol is reported to reduce the incidence of POAT. The authors studied the effect of magnesium chloride (MgCl2) in addition to sotalol in the prevention of POAT.

DESIGN

Prospective, randomized, double-blinded, placebo-controlled trial.

SETTING

Single center.

PARTICIPANTS AND INTERVENTIONS

After institutional approval and written informed consent, patients undergoing CABG with use of cardiopulmonary bypass were included in a prospective, randomized, placebo-controlled double-blind study. In 74 patients, intravenous MgCl2, 50 mmol/24 hours, was continuously administered after the induction of anesthesia during 36 hours; 73 patients received placebo. In both groups, sotalol orally was started 16 to 24 hours after CABG. The incidence and duration of in-hospital POAT were evaluated.

MEASUREMENTS AND MAIN RESULTS

A total of 147 patients could be evaluated: in the magnesium-treated group (n = 74), 25 patients developed POAT (34%) and in the placebo group (n = 73) 19 patients (26%) (p = 0.36). There was no statistically significant difference in duration of POAT between the groups. In the magnesium-treated group, 9 patients experienced serious bradyarrhythmias (12%), and in the placebo group no serious bradyarrhythmias were observed (p = 0.003). There was no mortality in either group.

CONCLUSIONS

These results show that MgCl(2), in addition to sotalol, is not more effective than sotalol alone in the prevention of tachyarrhythmias after CABG. The data showed that this combination may also induce serious bradyarrhythmias.

Oral Magnesium supplementation improves insulin sensitivity in non-diabetic subjects with insulin resistance. A double-blind placebo-controlled randomized trial

OBJECTIVE

Although hypomagnesemia reduces insulin sensitivity, benefits of magnesium supplementation to non-diabetic insulin resistant subjects has not been established. Our purpose was to determine whether oral magnesium supplementation with magnesium chloride (MgCl2) 2.5 g daily modify insulin sensitivity in non-diabetic subjects.

MATERIAL AND METHODS

This study was a 3 months randomized double-blind placebo-controlled trial. Apparently healthy subjects were eligible to participate if they had insulin resistance (HOMA-IR index equal or greater than 3.0) and hypomagnesemia (Serum magnesium levels equal or lower than 0.74 mmol/l). Subjects were randomized to receive either, MgCl2 2.5 g daily or placebo by 3-months.

RESULTS

At baseline there were not significant anthropometric or laboratory differences between both groups. At ending of the study, magnesium-supplemented subjects significantly increased their serum magnesium levels (0.61 +/- 0.08 to 0.81 +/- 0.08 mmol/l, p<0.0001) and reduced HOMA-IR index (4.6 +/- 2.8 to 2.6 +/- 1.1, p<0.0001), whereas control subjects did not (0.62 +/- 0.08 to 0.61 +/- 0.08 mmol/l, p=0.063 and 5.2 +/- 1.9 to 5.3 +/- 2.9, p=0.087).

CONCLUSIONS

Oral magnesium supplementation improves insulin sensitivity in hypomagnesemic non-diabetic subjects. Clinical implications of this finding have to be established.

Uptake of MnCl2and mangafodipir trisodium in the myocardium: A magnetic resonance imaging study in pigs

PURPOSE

To examine the changes in the longitudinal relaxation times (DeltaR1) induced in pig myocardium and blood following injections of 5, 10, and 15 micromol mangafodipir trisodium (Mn-DPDP) or MnCl2/kg of body weight (b.w.).

MATERIALS AND METHODS

Twelve pigs were divided into two groups, one group receiving MnCl2 and the other receiving Mn-DPDP. Three consecutive doses of contrast agent (5, 10, and 15 micromol/kg of b.w.) were injected in each animal with a 40-minute time interval between each dose. Measurements of T1 in blood and myocardium were made 5, 15, 25, and 35 minutes after each injection. Additionally, relaxivity measurements in blood samples were performed.

RESULTS

An increase in myocardial R1 was observed for both contrast agents at all concentration levels tested. This increase peaked 5 minutes after injection and then declined. An increase could still be detected 35 minutes after injection. The effect was larger when using MnCl2 than when using Mn-DPDP.

CONCLUSION

The dissociation kinetics of Mn2+ from the DPDP ligand limits the relaxation increase of Mn-DPDP relative to that of MnCl2. On the other hand, the toxicity of MnCl2 may exclude it from clinical use.

[Bishofit in the treatment of rheumatoid arthritis]

AIM

To evaluate effectiveness of a natural mineral bishofit in combined treatment of rheumatoid arthritis (RA).

MATERIAL AND METHODS

The study included 71 RA patients with minimal activity of the pathological process and articular disorders of stage II. Bishofit was used in baths and compresses. 33 AR patients of group 1 took bishofit baths (14 procedures) and non-steroid anti-inflammatory drugs (NSAID), 27 RA patients of group 2 were treated with bishofit compresses (14 procesures) and NSAID, 11 patients of group 3 (controls) received NSAID alone. The effect of the treatment was assessed on the basis of clinical data, the length of the affected joint circumference, antitryptic blood activity, activity of malate dehydrogenase, lactate dehydrogenase isoenzymes, plasmin, plasminogen, ESR, sialic acids.

RESULTS

Bishofit-treated patients showed earlier (by 5-6 days) and greater (by 25-35%) decrease of the pain, joint and inflammatory indices as well as duration of morning stiffness, length of the affected joint circumference and joint mobility, improvement of the tests' results. A response and an appreciable response to combined therapy with bishofit were achieved in 62.9-63.6% of cases vs 45.5% in the control group. Bishofit baths and compresses did not differ considerably by therapeutic efficacy.

Three-dimensional MRI of cerebral projections in rat brain in vivo after intracortical injection of MnCl2

In this study we investigated the potential of in vivo MRI detection of axonal Mn2+ transport for tracing neuronal projections originating in the sensorimotor cortex in healthy and lesioned rat brains. Special attention was given to the potential of visualizing neuronal sprouting of central nervous system across the midline. After injecting unchelated MnCl2 into the forelimb area of sensorimotor cortex of 18 healthy and 10 lesioned rats corticofugal projections could be traced through the internal capsule to the cerebral peduncle and the pyramidal decussation. Although the neuronal tract was visible as early as 6 h after MnCl2 injection, best contrast was achieved after 24-48 h. Beside the cortico-spinal tract, the cortico-thalamic fibres were also visualized by anterograde Mn2+ transport. Cortico-striatal fibres were partially masked by the very high signal near the MnCl2 injection site but could be discerned as well. Slight, diffuse signal enhancement of cortical tissue contralateral to the MnCl2 injection site in healthy rat brains suggests interhemispheric connections or passive diffusion of Mn2+. However, enhanced fibre tract contrast connecting both hemispheres was visible 16 weeks after onset of focal photothrombotic cortical injury. In conclusion our study has shown that we were able to visualize reproducibly the main descending corticofugal projections and interhemispheric connections by non-invasive MRI after localized injection of MnCl2. The appearance of interhemispheric Mn2+-enhanced fibres after photothrombotic focal injury indicates that the method may bear potential to follow non-invasively gross plastic changes of connectivity in the brain after injury.

Oral magnesium supplementation improves insulin sensitivity and metabolic control in type 2 diabetic subjects: a randomized double-blind controlled trial

OBJECTIVE

To determine whether oral magnesium supplementation (as magnesium chloride [MgCl(2)] solution) improves both insulin sensitivity and metabolic control in type 2 diabetic subjects with decreased serum magnesium levels.

RESEARCH DESIGN AND METHODS

This study was a clinical randomized double-blind placebo-controlled trial. A total of 63 subjects with type 2 diabetes and decreased serum magnesium (serum magnesium levels </=0.74 mmol/l) treated by glibenclamide received either 50 ml MgCl(2) solution (containing 50 g MgCl(2) per 1,000 ml solution) or placebo daily for 16 weeks. Chronic diarrhea, alcoholism, use of diuretic and/or calcium antagonist drugs, and reduced renal function were exclusion criteria. Homeostasis model assessment for insulin resistance (HOMA-IR) was used as the parameter of insulin sensitivity and glucose and HbA(1c) as parameters of metabolic control.

RESULTS

At the end of the study, subjects who received magnesium supplementation showed significant higher serum magnesium concentration (0.74 +/- 0.10 vs. 0.65 +/- 0.07 mmol/l, P = 0.02) and lower HOMA-IR index (3.8 +/- 1.1 vs. 5.0 +/- 1.3, P = 0.005), fasting glucose levels (8.0 +/- 2.4 vs. 10.3 +/- 2.1 mmol/l, P = 0.01), and HbA(1c) (8.0 +/- 2.4 vs. 10.1 +/- 3.3%, P = 0.04) than control subjects.

CONCLUSIONS

Oral supplementation with MgCl(2) solution restores serum magnesium levels, improving insulin sensitivity and metabolic control in type 2 diabetic patients with decreased serum magnesium levels.

Sulfur and chlorine play a non-acid base role in periparturient calcium homeostasis

The increased risk of periparturient hypocalcaemia through offering high-K feeds in the precalving period has been reported previously. Two experiments (experiment 1 and 2) investigated the effect of KCl fertilizer on pasture mineral concentration, the dietary cation-anion difference (DCAD), and the subsequent effect of this on periparturient plasma and urine mineral status. Experiment 2 examined the effect of precalving Mg source (MgO, MgSO4, and MgCl2) and postcalving Ca supplementation on the concentration of Ca and Mg in plasma and urine. Unexpectedly, pasture DCAD increased (P = 0.06) from 434 to 535 mEq/kg DM in experiment 1 as pasture K concentration decreased from 4.2 to 3.5%, primarily because of a corresponding and greater decrease in pasture Cl concentration (from 1.9 to 1.3%). Plasma Ca or Mg concentrations were not affected by pasture K concentration. A linear decline (P < 0.10) in urine Mg suggested a decline in Mg absorption as pasture K increased. In experiment 2, pasture DCAD decreased (P < 0.05) linearly from 403 to 350 mEq/kg DM as pasture K concentration decreased from 3.8 to 3.3%. However, precalving urine pH was not affected by the declining DCAD. Postcalving plasma Ca concentration was affected by precalving Mg source with MgSO4 > MgCl2 > MgO. Differences in acid-base balance do not explain the difference between Mg salts. These results indicate that precalving dietary S and Cl concentration plays an important role in Ca homeostasis, in addition to its role in acid-base balance. Supplementation with Ca postcalving increased plasma Ca concentration for 2 d postcalving. Milk production was not affected.

In vivo 3D MRI staining of mouse brain after subcutaneous application of MnCl2

Follow-up T(1)-weighted 3D gradient-echo MRI (2.35 T) of murine brain in vivo (N = 5) at 120 microm isotropic resolution revealed spatially distinct signal increases 6-48 hr after subcutaneous application of MnCl(2) (20 mg/kg). The effects result from a shortening of the water proton T(1) relaxation time due to the presence of unchelated paramagnetic Mn(2+) ions, which access the brain by systemic circulation and crossing of the blood-brain barrier (BBB). A pronounced Mn(2+)-induced signal enhancement was first seen in structures without a BBB, such as the choroid plexus, pituitary gland, and pineal gland. Within 24 hr after administration, Mn(2+) contrast highlighted the olfactory bulb, inferior colliculi, cerebellum, and the CA3 subfield of the hippocampus. The affinity of Mn(2+) to various brain systems suggests the neuronal uptake of Mn(2+) ions from the extracellular space and subsequent axonal transport. Thus, at least part of the Mn(2+) contrast reflects a functional brain response of behaving animals, for example, in the olfactory system. In vivo MRI staining of the brain by systemic administration of MnCl(2) may contribute to phenotyping mutant mice with morphologic and functional alterations of the central nervous system.

Intravenous nutrient therapy: the "Myers' cocktail"

Building on the work of the late John Myers, MD, the author has used an intravenous vitamin-and-mineral formula for the treatment of a wide range of clinical conditions. The modified "Myers' cocktail," which consists of magnesium, calcium, B vitamins, and vitamin C, has been found to be effective against acute asthma attacks, migraines, fatigue (including chronic fatigue syndrome), fibromyalgia, acute muscle spasm, upper respiratory tract infections, chronic sinusitis, seasonal allergic rhinitis, cardiovascular disease, and other disorders. This paper presents a rationale for the therapeutic use of intravenous nutrients, reviews the relevant published clinical research, describes the author's clinical experiences, and discusses potential side effects and precautions.

Detection of genetically modified coho salmon using polymerase chain reaction (PCR) amplification

A PCR-based protocol for the identification of genetically modified salmon carrying a growth hormone transgene was developed. Several primer pairs were examined, and the primers that gave consistent results were selected to conduct routine testing. Comparison among several DNA extraction procedures, as well as different buffer compositions, led to the adoption of TriZol as the method of choice. Low potassium and high magnesium chloride concentrations were very important in the overall success of the PCR reaction, whereas buffer pH, ranging from 8.3 to 9.2, had little impact on the amplification reaction. The optimal primer annealing temperature was 52 degrees C. Although fish muscle tissues were the primary source for DNA samples, detection of the transgene was also possible in bones, skin, fins, and other organs. No benefits were achieved by the addition of additives such as dimethyl sulfoxide and betaine to the PCR reaction. This optimized PCR method was used to identify all samples tested (61 samples and 17 controls) with 100% accuracy.

Development of brain damage as measured by brain impedance recordings, and changes in heart rate, and blood pressure induced by different stunning and killing methods

Poultry are electrically stunned before slaughter to induce unconsciousness and to immobilize the chickens for easier killing. From a welfare point of view, electrical stunning should induce immediate and lasting unconsciousness in the chicken. As an alternative to electroencephalography, which measures brain electrical activity, this study used brain impedance recordings, which measure brain metabolic activity, to determine the onset and development of brain damage. Fifty-six chickens were surgically equipped with brain electrodes and a canula in the wing artery and were subjected to one of seven stunning and killing methods: whole body electrical stunning; head-only electrical stunning at 50, 100 or 150 V; or an i.v. injection with MgCl2. After 30 s, the chickens were exsanguinated. Brain impedance and blood pressure were measured. Extracellular volume was determined from the brain impedance data and heart rate from the blood pressure data. An immediate and progressive reduction in extracellular volume in all chickens was found only with whole body stunning at 150 V. This treatment also caused cardiac fibrillation or arrest in all chickens. With all other electrical stunning treatments, extracellular volume was immediately reduced in some but not all birds, and cardiac fibrillation or arrest was not often found. Ischemic conditions, caused by cessation of the circulation, stimulated this epileptic effect. A stunner setting of 150 V is therefore recommended to ensure immediate and lasting unconsciousness, which is a requirement for humane slaughter.

Effect of magnesium on calcium-dependent brain function that prolongs ethanol-induced sleeping time in mice

The effect of intracerebroventricular (i.c.v.) administration of magnesium on calcium- and dopamine-dependent brain function was investigated behaviorally and biochemically. The duration of ethanol-induced sleeping time in mice was prolonged following i.c.v. administration of calcium chloride (10 micromol/kg) or dopamine (30nmol/mouse); however, it was not affected by magnesium chloride (10 or 40 micromol/kg). The ability of calcium to prolong ethanol-induced sleeping time was inhibited by the administration of magnesium chloride. The brain dopamine level in mice was significantly increased following i.c.v. administration of calcium chloride. Taking into consideration these results and those from previous studies, it is suggested that calcium enhances dopamine synthesis in the brain through a calmodulin-dependent system, and the increase in dopamine level prolongs ethanol-induced sleeping time. However, magnesium inhibits dopamine release. Therefore, magnesium may inhibit calcium-dependent brain function through dopaminergic neurons, and consequently reduce the effect of calcium on ethanol activity.

Effects of ATP-MgCl2 administration in hypovolemic dogs

BACKGROUND

The aim of the study was to evaluate the efficacy of ATP-MgCl2 on myocardial insufficiency associated with hypovolemic shock in dogs. We designed the study as a controlled randomized study.

METHODS

Six mixed-breed dogs weighing 22 +/- 3 kg were included in the control group and 20 +/- 3 kg in the ATP-MgCl2 group. After the animals were anesthetized 40 ml/kg of blood was withdrawn in 15 minutes. Animals were observed for 45 minutes after removal of blood. Six animals received 45 ml/kg of lactated Ringer's solution and the other animals were treated with 45 ml/kg of lactated Ringer's solution and ATP-MgCl2. All measurements were made before removal of blood, 45 min after exsanguination and at 1 hour intervals for 3 hours. The following parameters were measured; systemic and pulmonary arterial pressures, pulmonary capillary wedge pressure, central venous pressure, cardiac output, rectal temperature, arterial pH, PCO2 and PO2 and mixed venous hemoglobin oxygen saturation. In addition blood samples were collected for the analysis of lactate and tumor necrosis factor (TNF) concentrations.

RESULTS

After hemorrhage, cardiac index (CI) decreased significantly from 122 +/- 9 to 52 +/- 9 ml/kg/min in the control group (p < 0.0001) and from 124 +/- 11 ml/kg/min to 50 +/- 6 ml/kg/min in the ATP-MgCl2 group, respectively (p < 0.0001). After volume replacement, Cl was 93 +/- 6 ml/kg/min in the control group and 111 +/- 4 ml/kg/min in the ATP-MgCl2 group 3 hours after the onset of reinfusion, respectively (p < 0.05). TNF was 36 +/- 5 pg/ml in the control group and 21 +/- 3 pg/ml in the ATP-MgCl2 group (p < 0.05). Three hours after the onset of hemorrhagic shock, oxygen consumption and delivery were 126 +/- 14 and 206 +/- 19 ml/min in the control group and 198 +/- 16 and 305 +/- 27 ml/min in the ATP-MgCl2 group, respectively. At the same time point the oxygen extraction ratio was 0.49 +/- 0.04 in the control group and 0.61 +/- 0.03 in the ATP-MgCl2 group (p < 0.01).

CONCLUSIONS

Hemorrhagic shock causes TNF release which may cause multiple organ failure. Organ dysfunction still persists even after the appropriate treatment. ATP-MgCl2 attenuates the release of TNF which may improve the adverse effects of hemorrhagic shock.

Competition between Li+ and Mg2+ for red blood cell membrane phospholipids: A 31P, 7Li, and 6Li nuclear magnetic resonance study

The mode of action of the lithium ion (Li+) in the treatment of manic depression or bipolar illness is still under investigation, although this inorganic drug has been in clinical use for 50 yr. Several research reports have provided evidence for Li+/Mg2+ competition in biomolecules. We carried out this study to characterize the interactions of Li+ and Mg2+ with red blood cell (RBC) membrane components to see whether Li+/Mg2+ competition occurs. 31P nuclear magnetic resonance chemical shift measurements of the phospholipids extracted from the RBC membranes indicated that the anionic phospholipids, phosphatidylserine and phosphatidylinositol, bind Li+ and Mg2+ most strongly. From 6Li relaxation measurements, the Li+ binding constant to the phospholipid extract was found to be 45 +/- 5 M(-1). Thus, these studies showed that the phospholipids play a major role in metal ion binding. 7Li spin-lattice relaxation measurements conducted on unsealed and cytoskeleton-depleted RBC membrane in the presence of magnesium indicated that the removal of the cytoskeleton increases lithium binding to the more exposed anionic phospholipids (357 +/- 24 M(-1)) when compared to lithium binding in the unsealed RBC membrane (221 +/- 21 M(-1)). Therefore, it can be seen that the cytoskeleton does not play a major role in Li+ binding or in Li+/Mg2+ competition.

[Clinical and experimental rationale of policatan administration in upper respiratory tract inflammation]

Experimental and clinical trials of policatan in ENT inflammation have established that maximal antiinflammatory effect of the drug manifests in experimental serotonin, histamine and corragenin edema, less pronounced--in formaline-induced edema. The drug accelerated healing of infected burn ulcer in rabbit nose by 37%. This may be explained not only antiinflammatory effect of policatan, but also by stimulation of macrophage phagocytosis and bacteriostatic potential. Policatan proved effective in acute and chronic maxillary sinusitis, chronic frontal sinusitis and rhinitis, chronic hyperplastic maxilloethmoiditis. The drug reduced contamination with pathogenic and opportunistic microflora and reestablished saprophyte microflora.

Hemodynamic and metabolic alterations associated with intravenous infusion of a combination of adenosine triphosphate and magnesium chloride in conscious horses

OBJECTIVE

To determine hemodynamic and metabolic effects of IV infusion of ATP-MgCl2 combination and maximal safe IV infusion rate in conscious horses.

ANIMALS

6 adult female horses.

PROCEDURE

All horses received an IV infusion of ATP-MgCl2 combination, beginning at a rate of 0.05 mg of ATP/kg of body weight/min, which was increased by 0.05 mg/kg/min increments at 10-minute intervals until a rate of 1.0 mg/kg/min was achieved. Data were collected prior to the start of the infusion, at the end of each infusion rate, and at 15-minute intervals for the next hour after discontinuation of the infusion. Measured or calculated hemodynamic variables included cardiac output, cardiac index, heart rate, stroke volume, systemic and pulmonary arterial pressures, and systemic and pulmonary vascular resistances. Arterial blood gas tensions, CBC, plasma biochemical profiles, urine volume and specific gravity, and selected clinical signs of disease also were evaluated.

RESULTS

Intravenous infusion of ATP-MgCl2 significantly increased cardiac output, decreased systemic vascular resistance, and caused mild pulmonary hypertension. Magnitude of the hemodynamic alterations was dependent on rate of infusion. Maximal safe infusion rate for these horses was 0.3 mg/kg/min. All horses became lethargic, and their appetites diminished during the infusion; 5 horses had mild signs of abdominal discomfort. Flank sweating was observed in all horses as infusion rate increased. Urine volume and specific gravity and hematologic, biochemical, and arterial blood gas alterations were detected during and after infusion.

CONCLUSIONS AND CLINICAL RELEVANCE

Intravenous administration of ATP-MgCl2 in healthy, conscious, adult horses caused various metabolic and hemodynamic alterations that were without appreciable detrimental effects.

[The effect of polikatan on the ototoxic action of kanamycin]

Experiments on guinea pigs demonstrated that preliminary injection of polycatan (standardized magnesium solution containing the mineral bischofite) into the parotid region by means of electrophoresis reduces the ototoxic effect of the aminoglycoside antibiotic kanamycin. Polycatan prevents kanamycin-induced degenerative changes of the hair cells found in the labyrinth of the internal ear and improves the local blood flow.

Sequential pharmacotherapy with magnesium chloride and basic fibroblast growth factor after fluid percussion brain injury results in less neuromotor efficacy than that achieved with magnesium alone

Combinational pharmacotherapy with individually efficacious agents is a potential strategy for the treatment of traumatic central nervous system (CNS) injury. Basic fibroblast growth factor (bFGF) has been shown to be neuroprotective against excitotoxic, ischemic, and traumatic injury to the CNS, while acute posttraumatic treatment with magnesium (Mg2+) has been shown to decrease the motor and cognitive deficits following experimental brain injury. In this study, bFGF and Mg2+ were evaluated separately and in combination to assess their potential additive effects on posttraumatic neurological recovery and histological cell loss (lesion volume). Twenty minutes after fluid percussion (FP) brain injury of moderate severity (2.2-2.4 atm), anesthetized rats received a 15-min intravenous infusion of either 125 mumol of MgCl2 or vehicle, followed 5 min later by a 24-h constant intravenous infusion of either bFGF (16 micrograms/h) or vehicle. Injured animals had a significant motor deficit when compared to sham (uninjured) animals at both 48 h and 7 days postinjury. At 48 h postinjury, there were no significant differences among injured animals when compared by treatment. By 7 days postinjury, injured animals treated with MgCl2 alone displayed significantly improved motor function when compared to brain-injured, vehicle-treated animals (p < 0.05). Animals treated with either bFGF alone or a combination of MgCl2 and bFGF displayed no significant neurological improvement relative to vehicle-treated injured animals at 7 days. No effect of any drug treatment of combination was observed on the extent of the postinjury lesion volume in the injured cortex. These results suggest that caution must be exercised when combining "cocktails" of potentially neuroprotective compounds in the setting of traumatic brain injury.

Oral magnesium for tocolysis: a comparison of magnesium gluconate and enteric-coated magnesium chloride

PURPOSE

Following parenteral magnesium tocolysis for patients in preterm labor. The choice of oral tocolytic medications is controversial.

METHODS

Over a six-month period, 47 patients who were inpreterm labor were randomized after parenteral magnesium tocolysis to receive magnesium gluconate ([Mg-g] 648 mg elemental magnesium/day) or magnesium chloride ([Mg-c] 640 mg elemental magnesium/ day). A serum magnesium was obtained 24 hours after the initiation of oral therapy.

RESULTS

In the 25 patients were treated with Mg-g and 22 with Mg-c there were no differences in patient demographics, initial cervical dilatation hours on parenteral magnesium sulfate, recurrent contractions, or side effects between the two groups. The cost was also similar (Mg-c, $1.40/d; Mg-g, $2.11/d). The serum magnesium levels were higher in the Mg-c group (1.80 +/- 0.28 mg/dl) compared to the Mg-g group (1.63 +/- 0.30 mg/dl) but the difference was not significant.

CONCLUSION

These two preparations of magnesium are similar in their effects on uterine activity and serum levels when used at these dosages.

Multiplex PCR: critical parameters and step-by-step protocol

By simultaneously amplifying more than one locus in the same reaction, multiplex PCR is becoming a rapid and convenient screening assay in both the clinical and the research laboratory. While numerous papers and manuals discuss in detail conditions influencing the quality of PCR in general, relatively little has been published about the important experimental factors and the common difficulties frequently encountered with multiplex PCR. We have examined various conditions of the multiplex PCR, using a large number of primer pairs. Especially important for a successful multiplex PCR assay are the relative concentrations of the primers at the various loci, the concentration of the PCR buffer, the cycling temperatures and the balance between the magnesium chloride and deoxynucleotide concentrations. Based on our experience, we propose a protocol for developing a multiplex PCR assay and suggest ways to overcome commonly encountered problems.