Acute barium poisoning with respiratory failure and rhabdomyolysis

Subchronic pulmonary toxicity of ambient particles containing cement production-related elements

Chronic respiratory disease is among the most common non-communicable diseases, and particulate materials (PM) are a major risk factor. Meanwhile, evidence of the relationship between the physicochemical characteristics of PM and pulmonary toxicity mechanism is still limited. Here, we collected particles (CPM) from the air of a port city adjacent to a cement factory, and we found that the CPM contained various elements, including heavy metals (such as arsenic, thallium, barium, and zirconium) which are predicted to have originated from a cement plant adjacent to the sampling site. We also delivered the CPM intratracheally to mice for 13 weeks to investigate the pulmonary toxicity of inhaled CPM. CPM-induced chronic inflammatory lesions with an increased total number of cells in the lung of mice. Meanwhile, among inflammatory mediators measured in this study, levels of IL-1β, TNF-α, CXCL-1, and IFN-γ were elevated in the treated group compared with the controls. Considering that the alveolar macrophage (known as dust cell) is a professional phagocyte that is responsible for the clearance of PM from the respiratory surfaces, we also investigated cellular responses following exposure to CPM in MH-S cells, a mouse alveolar macrophage cell line. CPM inhibited cell proliferation and formed autophagosome-like vacuoles. Intracellular calcium accumulation and oxidative stress, and altered expression of pyrimidine metabolism- and olfactory transduction-related genes were observed in CPM-treated cells. More interestingly, type I-LC3B and full-length PARP proteins were not replenished in CPM-treated cells, and cell cycle changes, apoptotic and necrotic cell death, and caspase-3 cleavage were not significantly detected in cells exposed to CPM. Taken together, we conclude that dysfunction of alveolar macrophages may contribute to CPM-induced pulmonary inflammation. In addition, given the possible transformation of heart tissue observed in CPM-treated mice, we suggest that further study is needed to clarify the systemic pathological changes and the molecular mechanisms following chronic exposure to CPM.

Life-threatening barium carbonate poisoning managed with intravenous potassium, continuous veno-venous haemodialysis and endoscopic removal of retained ceramic glazes

INTRODUCTION

Barium poisoning is rare but potentially severe. We describe a case of acute barium carbonate poisoning with cardiac arrest, managed with intravenous potassium, dialysis and endoscopic removal of retained ceramic glazes.

CASE REPORT

A 38-year-old woman presented with vomiting 90 min after ingesting 3 cups of barium and strontium carbonate. Initial bloods noted potassium 2.8 mmol/L and creatinine 53 μmol/L. Electrocardiogram demonstrated prolonged corrected QT interval 585msec. Initial management included intravenous potassium. Four hours post-ingestion she developed proximal muscle weakness in upper limbs with a potassium of 2.2 mmol/L. At 15 h post-ingestion she developed profound muscle weakness, polymorphic ventricular tachycardia and cardiac arrest. Treatment included defibrillation, endotracheal intubation and continuous veno-venous haemodialysis (CVVHD) for metabolic derangement and enhanced elimination of barium. Chest X-ray 17 h post-ingestion demonstrated a large radio-opaque mass in the stomach, thought to be the ceramic glaze. Endoscopy removed the retained material 41 h post-ingestion. She was extubated 58 h post-ingestion and CVVHD was ceased on day 3. Serum creatinine peaked at 348 μmol/L on day 7, but normalised by discharge. Biphasic barium concentrations were noted, notably 94 μmol/L on admission, 195 μmol/L at 16 h, 95 μmol/L at 20 h, and 193 μmol/L at 30 h post-ingestion.

CONCLUSION

In barium poisoning with hypokalaemia, prompt potassium supplementation is required but rebound hyperkalaemia can occur. Endoscopic removal of ceramic glazes may be useful more than 12 h post-ingestion. Consider extracorporeal methods to enhance barium elimination in severe cases.

Analytical survey of tattoo inks-A chemical and legal perspective with focus on sensitizing substances

BACKGROUND

Tattoo inks have been reported to elicit allergic contact dermatitis.

OBJECTIVES

To investigate the labels and the contents of metals and pigments in tattoo inks, considering restrictions within the European Union.

METHODS

Seventy-three tattoo inks currently available on the market, either bought or donated (already used), were investigated for trace metals and pigments by inductively coupled plasma mass spectrometry and by matrix-assisted laser desorption/ionization time of flight tandem mass spectrometry.

RESULTS

Ninety-three percent of the bought tattoo inks violated European, legal requirements on labeling. Fifty percent of the tattoo inks declared at least one pigment ingredient incorrectly. Sixty-one percent of the inks contained pigments of concern, especially red inks. Iron, aluminium, titanium, and copper (most in green/blue inks) were the main metals detected in the inks. The level of metal impurities exceeded current restriction limits in only a few cases. Total chromium (0.35-139 μg/g) and nickel (0.1-41 μg/g) were found in almost all samples. The levels of iron, chromium, manganese, cobalt, nickel, zinc, lead, and arsenic were found to covary significantly.

CONCLUSIONS

To prevent contact allergy and toxic reactions among users it is important for tattoo ink manufacturers to follow the regulations and decrease nickel and chromium impurities.

An unwitnessed case of foreign body aspiration of barium from an unknown source

Foreign body (FB) aspiration is potentially life-threatening in children. A variety of sources and objects have been noted in aspiration events with possible complications ranging from mild to life-threatening. While rare, barium aspiration can cause severe complications, and removal is particularly challenging. Complications of retained barium include acute respiratory distress syndrome, pneumonitis, sepsis, even death. Regardless of the foreign body's identity, substance removal is critical in management. Resourcefulness of removal techniques and an interdisciplinary approach may allow for maximally effective management. We present a case of a pediatric barium aspiration from an unknown source and review evaluation and management strategies.

Water Quality for Cattle: Metalloid and Metal Contamination of Water

Water is the most important nutrient for rangeland livestock. However, competition with municipalities, industry, and other water users often results in grazing livestock being forced to use water supplies that are less than perfect. Surface water in western rangleands are often contaminated by mineral extraction, irrigation runoff and other human activities. Mineral contaminants in drinking water are additive with similar contaminants in feedstuffs. The goal of this article is to provide producers and veterinarians with the basic background to make informed decisions about whether a given water supply is "safe" for livestock.

A newly validated and characterized spectrophotometric method for determination of a three water pollutants metal ions

A simple, fast and accurate spectrophotometric method had been developed to determine lead (II), chromium (III) and barium (II) ions in pure forms and in spiked water samples using thoron (THO) as a reagent forming colored complexes. It was found that the formed complexes absorbed maximally at 539, 540 and 538nm for Pb(II)-THO, Cr(III)-THO and Ba(II)-THO complexes, respectively. The optimum experimental conditions for these complexes had been studied carefully. Beer's law was obeyed in the range 1-35, 1-70, and 1-45μgmL^-1 for Pb (II), Cr(III) and Ba(II) ions with THO reagent, respectively. Different parameters such as linearity, selectivity, recovery, limits of quantification and detection, precision and accuracy were also evaluated in order to validate the proposed method. The results showed that, THO was effective in simultaneous determination of Pb(II), Cr(III) and Ba(III) ions in pure forms and in spiked water samples. Also, the results of the proposed method were compared with that obtained from atomic absorption spectrometry. The isolated solid complexes had been characterized using elemental analysis, X-ray powder diffraction (XRD), IR, mass spectrometry and TD-DFT calculations. Their biological activities were investigated against different types of bacteria and fungi organisms.

Essential and toxic element concentrations in monofloral honeys from southern Croatia

The concentrations of 24 elements in seven honey types (multifloral, heather, common heather, bearberry, sage, mandarin orange-blossom and honeydew) collected in southern Mediterranean regions of Croatia were determined using ICP-MS. Significant differences were found in the concentrations of Ag, As, Ba, Cu, Co, Fe, K, Mg, Mn, Mo, Na, Ni, Se, Sb, U and Th (p<0.05, all) among honeys. The highest element concentrations were determined in honeydew honeys, with the exception of multifloral (Ca, Cr, Mo, Se), common heather (Mg, Na), bearberry (Ba, Fe, Pb) and sage (Ag) honeys. Among the floral honeys, the highest concentrations were found in multifloral honey (Al, As, Be, Ca, Cr, Mn, Mo, Ni, Se, Th and U), common heather (Co, K, Mg, Na, V), sage (Ag, Cd, Cu), and bearberry (Ba, Fe, Pb, Sb, Zn). The results contribute to the evidence supporting the role of botanical origin on the elemental composition of honey.

Fatal barium chloride poisoning: four cases report and literature review

Barium is an alkaline earth metal which has a variety of uses including in the manufacturing industry and in medicine. However, adverse health effects and fatalities occur due to absorption of soluble barium compounds, notably the chloride, nitrate, and hydroxide, which are toxic to humans. Although rare, accidental and suicidal modes of poisoning are sporadically reported in the literature.We describe 4 cases of poisoning due to barium chloride in China. In witnessed cases, severe gastrointestinal symptoms, hypokalemia leading to muscle weakness, cardiac arrhythmias, and respiratory failure were noted. Autopsy showed some nonspecific but common findings, such as subendocardial hemorrhage in the ventricles, visceral petechiae, and fatty changes in the liver. Interestingly, microscopic examination showed degenerative changes and amorphous, flocculent foamy materials in the renal tubules. Toxicology was relevant for barium in blood and tissues. Three of the cases were accidental and 1 homicidal in nature. A round-up of relevant literature on fatal barium compounds poisoning is also provided. Forensic pathologists should be aware of the clinical presentations of barium compound poisoning and especially look for any evidence of hypokalemia. Still, postmortem toxicological and histological studies are essential for an accurate identification of the cause of death.

A review of the health impacts of barium from natural and anthropogenic exposure

There is an increasing public awareness of the relatively new and expanded industrial barium uses which are potential sources of human exposure (e.g., a shale gas development that causes an increased awareness of environmental exposures to barium). However, absorption of barium in exposed humans and a full spectrum of its health effects, especially among chronically exposed to moderate and low doses of barium populations, remain unclear. We suggest a systematic literature review (from 1875 to 2014) on environmental distribution of barium, its bioaccumulation, and potential and proven health impacts (in animal models and humans) to provide the information that can be used for optimization of future experimental and epidemiological studies and developing of mitigative and preventive strategies to minimize negative health effects in exposed populations. The potential health effects of barium exposure are largely based on animal studies, while epidemiological data for humans, specifically for chronic low-level exposures, are sparse. The reported health effects include cardiovascular and kidney diseases, metabolic, neurological, and mental disorders. Age, race, dietary patterns, behavioral risks (e.g., smoking), use of medications (those that interfere with absorbed barium in human organism), and specific physiological status (e.g., pregnancy) can modify barium effects on human health. Identifying, evaluating, and predicting the health effects of chronic low-level and moderate-level barium exposures in humans is challenging: Future research is needed to develop an understanding of barium bioaccumulation in order to mitigate its potential health impacts in various exposured populations. Further, while occupationally exposed at-risk populations exist, it is also important to identify potentially vulnerable subgroups among non-occupationally exposed populations (e.g., elderly, pregnant women, children) who are at higher risk of barium exposure from drinking water and food.

Extracellular potassium homeostasis: insights from hypokalemic periodic paralysis

Extracellular potassium makes up only about 2% of the total body's potassium store. The majority of the body potassium is distributed in the intracellular space, of which about 80% is in skeletal muscle. Movement of potassium in and out of skeletal muscle thus plays a pivotal role in extracellular potassium homeostasis. The exchange of potassium between the extracellular space and skeletal muscle is mediated by specific membrane transporters. These include potassium uptake by Na(+), K(+)-adenosine triphosphatase and release by inward-rectifier K(+) channels. These processes are regulated by circulating hormones, peptides, ions, and by physical activity of muscle as well as dietary potassium intake. Pharmaceutical agents, poisons, and disease conditions also affect the exchange and alter extracellular potassium concentration. Here, we review extracellular potassium homeostasis, focusing on factors and conditions that influence the balance of potassium movement in skeletal muscle. Recent findings that mutations of a skeletal muscle-specific inward-rectifier K(+) channel cause hypokalemic periodic paralysis provide interesting insights into the role of skeletal muscle in extracellular potassium homeostasis. These recent findings are reviewed.

Acute barium intoxication following ingestion of soap water solution

We present a rare case in which a young girl ingested a solution of a hair-removing soap. The ingestion resulted in profound hypokalemia and severe acidosis leading to flaccid paralysis, respiratory arrest and ventricular arrhythmias. Ultimately the patient made complete recovery. The soapwas found to contain barium sulfide. The degree of paralysis and acidosis appeared to be directly related to serum potassium levels.

Application of ICP-OES to the determination of barium in blood and urine in clinical and forensic analysis

Exposure to barium (Ba) mostly occurs in the workplace or from drinking water, but it may sometimes be due to accidental or intentional intoxication. This paper presents a reliable, sensitive method for the determination of Ba in blood and urine: inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave digestion of samples. The overall procedure was checked using Seronorm Whole Blood L-2, Trace Elements Urine and spiked blood and urine samples (0.5-10 µg/mL of Ba). The accuracy of the whole procedure (relative error) was 4% (blood) and 7% (urine); the recovery was 76-104% (blood) and 85-101% (urine). The limits of detection and quantification (Ba λ = 455.403 nm) were 0.11 and 0.4 µg/L of Ba, respectively; precision (relative standard deviation) was below 6% at the level of 15 µg/L of Ba for blood. This method was applied to a case of the poisoning of a man who had been exposed at the workplace for over two years to powdered BaCO3, and who suffered from paralysis and heart disorders. The concentrations of Ba, in μg/L, were 160 (blood), 460 (serum) and 1,458 (urine) upon his admission to the hospital, and 6.1 (blood) and 4.9 (urine) after 11 months (reference values: 3.34 ± 2.20 µg/L of Ba for blood and 4.43 ± 4.60 µg/L of Ba for urine).

Toxicology of explosives and fireworks in small animals

Intoxication with explosives or fireworks in dogs or cats is not common, but serious toxicosis can result from exposure to different types of explosives depending on the chemical class of explosive involved. This article will discuss the different types of materials/chemicals, clinical signs of toxicosis, and their treatment. Despite the complexities of explosives and plethora of different devices currently in use worldwide, the toxic potential is more easily explained by looking at the relatively short list of chemical classes used to produce these materials. This article combines structurally similar explosives into different groups and focuses on the toxicity of the most commonly available explosives.

The mammalian K(IR)2.x inward rectifier ion channel family: expression pattern and pathophysiology

Inward rectifier currents based on K(IR)2.x subunits are regarded as essential components for establishing a stable and negative resting membrane potential in many excitable cell types. Pharmacological inhibition, null mutation in mice and dominant positive and negative mutations in patients reveal some of the important functions of these channels in their native tissues. Here we review the complex mammalian expression pattern of K(IR)2.x subunits and relate these to the outcomes of functional inhibition of the resultant channels. Correlations between expression and function in muscle and bone tissue are observed, while we recognize a discrepancy between neuronal expression and function.

Intoxication by large amounts of barium nitrate overcome by early massive K supplementation and oral administration of magnesium sulphate

Suicide by ingestion of barium is exceptionally rare. Adverse health effects depend on the solubility of the barium compound. Severe hypokalemia, which generally occurs within 2 hours after ingestion, is the predominating feature of acute barium toxicity, subsequently leading to adverse effects on muscular activity and cardiac automaticity. We report one case of acute poisoning with barium nitrate, a soluble barium compound. A 75-year-old woman was hospitalized after suicidal ingestion of a burrow mole fumigant containing 12.375 g of barium nitrate. About 1 hour post-ingestion, she was only complaining of abdominal pain. The ECG recording demonstrated polymorphic ventricular premature complexes (VPCs). Laboratory data revealed profound hypokalemia (2.1 mmol/L). She made a complete and uneventful recovery after early and massive potassium supplementation combined with oral magnesium sulphate to prevent barium nitrate absorption.

Acute barium toxicity from ingestion of "snake" fireworks

INTRODUCTION

Ingestion of fireworks has been infrequently reported in the medical literature. We describe a case of acute barium poisoning following firework ingestion.

CASE REPORT

A 35-year-old male with a history of severe mental retardation presented with vomiting and diarrhea following ingestion of 16 small fireworks ("color snakes" and "black snakes"). His condition rapidly deteriorated and he developed obtundation, wide complex dysrhythmias, and respiratory failure. Approximately 12 hours following ingestion, his serum potassium level was 1.5 mmol/L with a serum barium level of 20,200 microg/mL (reference range <200 microg/L). The patient eventually recovered with ventilatory support and potassium supplementation.

DISCUSSION

Although firework ingestion is uncommon, clinicians should be prepared for potentially severe complications. In the case of barium poisoning, treatment consists of potassium supplementation, along with respiratory and hemodynamic support.

Mass barium carbonate poisoning with fatal outcome, lessons learned: a case series

INTRODUCTION

Barium, a heavy divalent alkaline metal, has long been known to cause human toxicity. The common mode is accidental ingestion and the common compound is Barium carbonate. Here we report an incident of food poisoning in 27 law enforcement personnel with rapidly developing sequelae and a high mortality due to ingestion of Barium carbonate contaminated flour.

CASE PRESENTATION

One midnight, 27 adult males were rushed to emergency department of Chittagong Medical College Hospital with abdominal pain, vomiting, loose motion, cramps and generalized paraesthesia. The ailment started 1-2 hours after Iftar (evening meal to break day long fast during Ramadan) which included fried vegetables coated with a flour paste. On admission, twenty of them were restless, agitated. 22 reported weakness of limbs and were unable to walk. 10 had hypotension. 22 had rapid and shallow respiration. 5 had carpopedal spasm. Different grades of limb weakness were noted with loss of tendon jerks. Ten (N12) patients had hypokalaemia, three had hypoglycaemia, 4 patients had high creatine kinase. Electrocardiogram showed flat ST with U waves in 4 patients. Potassium containing intravenous fluid and Oxygen was administered. Due to limited availability of mechanical ventilators patients were put on artificial respiration using Ambu bag; manually maintained by doctors, paramedics and attendants. Four patients were transferred to another hospital for mechanical ventilation. A total of 12 patients died over next 16 hours, 4 within 3 hrs. Other patients gradually improved. Chemical analysis of the vomitus, blood and flour used for preparation of meal revealed the presence of Barium. It was assumed that the flour was contaminated with the similar looking Barium carbonate powder which was kept in the kitchen as a rodenticide.

CONCLUSION

This event exemplifies the weakness of usual health care facility in resource poor settings to cope with this kind of massive poisoning event. The multiple reported incidences of accidental Barium poisoning due to unintentional mixing with food signifies the fact that the use and availability of Barium carbonate should be restricted. We hope to draw attention to this relatively uncommon poisoning and to the need for development of poison information centre in resource poor countries.

Mass barium carbonate poisoning with fatal outcome, lessons learned: a case series

INTRODUCTION

Barium, a heavy divalent alkaline metal, has long been known to cause human toxicity. The common mode is accidental ingestion and the common compound is Barium carbonate. Here we report an incident of food poisoning in 27 law enforcement personnel with rapidly developing sequelae and a high mortality due to ingestion of Barium carbonate contaminated flour.

CASE PRESENTATION

One midnight, 27 adult males were rushed to emergency department of Chittagong Medical College Hospital with abdominal pain, vomiting, loose motion, cramps and generalized paraesthesia. The ailment started 1-2 hours after Iftar (evening meal to break day long fast during Ramadan) which included fried vegetables coated with a flour paste. On admission, twenty of them were restless, agitated. 22 reported weakness of limbs and were unable to walk. 10 had hypotension. 22 had rapid and shallow respiration. 5 had carpopedal spasm. Different grades of limb weakness were noted with loss of tendon jerks. Ten (N12) patients had hypokalaemia, three had hypoglycaemia, 4 patients had high creatine kinase. ECG showed flat ST with U waves in 4 patients. Potassium containing intravenous fluid and Oxygen was administered. Due to limited availability of mechanical ventilators patients were put on artificial respiration using Ambu bag; manually maintained by doctors, paramedics and attendants. Four patients were transferred to another hospital for mechanical ventilation. A total of 12 patients died over next 16 hours, 4 within 3 hrs. Other patients gradually improved. Chemical analysis of the vomitus, blood and flour used for preparation of meal revealed the presence of Barium. It was assumed that the flour was contaminated with the similar looking Barium carbonate powder which was kept in the kitchen as a rodenticide.

CONCLUSION

This event exemplifies the weakness of usual health care facility in resource poor settings to cope with this kind of massive poisoning event. The multiple reported incidences of accidental barium poisoning due to unintentional mixing with food signifies the fact that the use and availability of barium carbonate should be restricted. We hope to draw attention to this relatively uncommon poisoning and to the need for development of poison information centre in resource poor countries.

Phenotypic and behavioral defects caused by barium exposure in nematode Caenorhabditis elegans

To examine the possible phenotypic defects from barium exposure, a model organism, Caenorhabditis elegans, was chosen to analyze the multiple toxicities in barium-exposed animals. Endpoints of life span, body size, brood size, generation time, head thrash, and body bend were selected for the assessment of barium toxicity. High concentrations (75 microM and 200 microM) of barium exposure caused severe life-span defects. Body sizes of exposed animals were markedly reduced compared to the controls, and high concentrations of barium exposure (75 microM and 200 microM) caused the appearance of vulva abnormality. In addition, barium exposure resulted in severe defects in reproductive capacity and reproductive speed. Body bends and head thrashes were also severely impaired after barium exposure. Furthermore, the stress responses to barium exposure suggest severe barium toxicity. The observed severe locomotion behavior and life-span defects in nematodes might be largely due to the deposition of barium toxicity in the muscle and intestine systems, respectively. Our data suggest that barium exposure could cause multiple biological defects by affecting the life span, development, reproduction, and locomotion behaviors. These multiple biological defects provide a new evaluation system to monitor the toxicity from barium exposure.

Hypophosphatemia: an evidence-based approach to its clinical consequences and management

Optimal cellular function is dependent on maintenance of a normal serum phosphorus concentration. Serum phosphorus concentration is affected by several determinants, the most important of which is regulation of phosphorus reabsorption by the kidney. The majority of this reabsorption (80%) occurs in the proximal tubule and is mediated by an isoform of the sodium-phosphate cotransporter (NaPi-II). Parathyroid hormone, via a variety of intracellular signaling cascades leading to NaPi-IIa internalization and downregulation, is the main regulator of renal phosphate reabsorption. Shift of phosphorus from extracellular to intracellular compartments, decreased gastrointestinal absorption, and increased urinary losses, are the primary mechanisms of hypophosphatemia, which affects approximately 2% of hospitalized patients. Hypophosphatemia has been implicated as a cause of rhabdomyolysis, respiratory failure, hemolysis and left ventricular dysfunction. With the exception of ventilated patients, there is little evidence that moderate hypophosphatemia has significant clinical consequences in humans, and aggressive intravenous phosphate replacement is unnecessary. By contrast, patients with severe hypophosphatemia should be treated. Intravenous repletion may be considered, especially for patients who have clinical sequelae of hypophosphatemia.

The speciation of metals in mammals influences their toxicokinetics and toxicodynamics and therefore human health risk assessment

Chemical form (i.e., species) can influence metal toxicokinetics and toxicodynamics and should be considered to improve human health risk assessment. Factors that influence metal speciation (and examples) include: (1) carrier-mediated processes for specific metal species (arsenic, chromium, lead and manganese), (2) valence state (arsenic, chromium, manganese and mercury), (3) particle size (lead and manganese), (4) the nature of metal binding ligands (aluminum, arsenic, chromium, lead, and manganese), (5) whether the metal is an organic versus inorganic species (arsenic, lead, and mercury), and (6) biotransformation of metal species (aluminum, arsenic, chromium, lead, manganese and mercury). The influence of speciation on metal toxicokinetics and toxicodynamics in mammals, and therefore the adverse effects of metals, is reviewed to illustrate how the physicochemical characteristics of metals and their handling in the body (toxicokinetics) can influence toxicity (toxicodynamics). Generalizing from mercury, arsenic, lead, aluminum, chromium, and manganese, it is clear that metal speciation influences mammalian toxicity. Methods used in aquatic toxicology to predict the interaction among metal speciation, uptake, and toxicity are evaluated. A classification system is presented to show that the chemical nature of the metal can predict metal ion toxicokinetics and toxicodynamics. Essential metals, such as iron, are considered. These metals produce low oral toxicity under most exposure conditions but become toxic when biological processes that utilize or transport them are overwhelmed, or bypassed. Risk assessments for essential and nonessential metals should consider toxicokinetic and toxicodynamic factors in setting exposure standards. Because speciation can influence a metal's fate and toxicity, different exposure standards should be established for different metal species. Many examples are provided which consider metal essentiality and toxicity and that illustrate how consideration of metal speciation can improve the risk assessment process. More examples are available at a website established as a repository for summaries of the literature on how the speciation of metals affects their toxicokinetics.

Acute barium nitrate intoxication treated by hemodialysis

A 22-year-old male was admitted to hospital with diarrhea and vomiting, cardiac arrhythmias, severe hypokalemia and gradual onset of muscular weakness. A potassium infusion was started, but for several hours serum potassium remained low. Evidence of toxic ingestion was initially lacking. When it became clear -- after a considerable delay -- that the patient had ingested barium nitrate, hemodialysis was started. This resulted in rapid clinical improvement with correction of hypokalemia and restored muscular function. Intoxication with barium causes hypokalemia, arrhythmias, muscular weakness and paralysis, often requiring respiratory support. This patient presented with symptoms typical of severe barium intoxication, non-responsive to potassium supplementation. There are few published reports on the use of hemodialysis in barium poisoning. This case confirms the possible benefit of hemodialysis in severe cases, where potassium supplementation alone is insufficient.

Acute barium intoxication and hemodiafiltration

We report a case of severe hypokalemia and flaccid muscle paralysis following a suicide attempt associating the calcium channel blocker amlodipine, the antidepressant fluoxetine and barium carbonate. Despite rapid correction of severe, life-threatening hypokalemia, areflexic quadriplegia persisted, suggesting a direct effect of barium on muscle cells. Continuous veno-venous hemodiafiltration (CVVHDF) was initiated. We determined barium concentration in the urine, plasma, and hemodiafiltrate during CVVHDF. We subsequently calculated the amounts of barium eliminated both by the CVVHDF and the kidneys. CVVHDF triples the measured barium elimination, reduced serum barium half-life by a factor of three, stabilized serum potassium levels, and rapidly improved motor strength, with complete neurological recovery within 24 h. Presentation and treatment of barium intoxication are discussed.

Poisoning as a result of barium styphnate explosion

BACKGROUND

Acute barium poisoning is most often the result of accidental or suicidal ingestion of the rodenticide, barium carbonate. We describe a trauma patient whose condition was complicated by severe acute barium toxicity from an explosion of the propellant, barium styphnate. In addition to critical injuries, the patient manifested classic signs of barium toxicity including repeated profound hypokalemia, cardiac arrhythmias, respiratory failure, prolonged gastrointestinal dysfunction, paralysis, myoclonus, hypertension, and profound lactic acidosis.

METHODS

The patient required lidocaine for ventricular bigeminy, massive infusions of potassium, prolonged ventilatory support, and parenteral nutrition to manage the effects of barium toxicity.

RESULTS

He is the first reported case to demonstrate recurrent profound hypokalemia as an effect of blood transfusions.

CONCLUSIONS

Considering the paucity of information concerning management of this life-threatening problem, the pathophysiology of barium toxicity, including the transfusion related hypokalemia, and its management is reviewed.

Barium reduces resting blood flow and inhibits potassium-induced vasodilation in the human forearm

BACKGROUND

Increasing extracellular K+ concentration within and just above the physiological range hyperpolarizes and relaxes vascular smooth muscle in vitro. These actions involve inwardly rectifying potassium channels (K(IR)) and Na+/K+ ATPase, which are inhibited, respectively, by Ba2+ and ouabain. The role (if any) of K(IR) in controlling human resistance vessel tone is unknown, and we investigated this in the forearm.

METHODS AND RESULTS

Blood flow was measured by plethysmography in healthy men. Drugs and electrolytes were infused through the brachial artery. BaCl2 (4 micromol/min, also used in subsequent experiments) increased Ba2+ plasma concentration in the infused forearm to 50+/-0.8 micromol/L (mean+/-SEM) and reduced blood flow by 24+/-4% (n=8, P<0.001) without causing systemic effects. Ouabain (2.7 nmol/min), alone and with BaCl2, reduced flow by 10+/-2% and 28+/-3%, respectively (n=10). Incremental infusions of KCl (0.05, 0.1, and 0.2 mmol/min) increased flow from baseline by 1.0+/-0.2, 2.0+/-0.4, and 4.2+/-0.5 mL/min per deciliter forearm, respectively. Responses to KCl (0.2 mmol/min) were inhibited by BaCl2, alone and plus ouabain, by 60+/-9% and 88+/-6%, respectively (both P< or =0.01). In control experiments, norepinephrine (240 pmol/min) reduced blood flow by 24+/-2% but had no significant effect on K+-induced vasodilation. BaCl2, alone or with ouabain, did not significantly influence responses to verapamil or nitroprusside.

CONCLUSIONS

Ba2+ increases forearm vascular resistance. K+-induced vasodilation is selectively inhibited by Ba2+ and almost abolished by Ba2+ plus ouabain, suggesting a role for K(IR) and Na+/K+ ATPase in controlling basal tone and in K+-induced vasorelaxation in human forearm resistance vessels.

Effect of replacement of the tightly bound Ca2+ by Ba2+ on actin polymerization

G-actin has a single tight-binding (high-affinity) site for divalent cations per mole of protein, whose occupancy is important for the stability of the molecule. Different tightly bound divalent cations differently influence the polymerization properties of actin. The tightly bound metal ion easily exchanges for free exogenous cations. Moreover, biochemical and structural evidence demonstrates that actin, in both the G- and F-forms, assumes different conformations depending on the metal ion bound with high affinity in the cleft between two main domains of the molecule. In this work, we used proteolytic susceptibility to detect possible local conformational alterations of the actin molecule following a brief incubation of Ca-G-actin with barium chloride and ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid. We found that substitution of Ba2+ for the tightly bound Ca2+ affects the regions around Arg-62 and Lys-68 in subdomain 2 of G-actin, as judged from inhibition of tryptic cleavage at these residues. Using the fluorescent chelator Quin-2, we observed that about 0.95 mol of Ba2+ is released per 1 mol of actin. We also examined the effect of replacement of the tightly bound Ca2+ by Ba2+ on actin polymerization. With respect to Ca-actin, Ba-actin shows an increased polymerization rate, mainly due to its enhanced nucleation and a higher critical concentration.

Disturbances of potassium homeostasis in poisoning

Unless renal function is impaired or rhabdomyolysis is severe, hyperkalemia is a relatively uncommon metabolic complication of poisoning. In contrast, marked hypokalemia is a more common problem and may have serious sequelae. Most potassium disturbances in acute poisoning are due to disruption of extra-renal control mechanisms, notably the activity of Na+/K+ ATPase and K+ channels. Hypokalemia occurs because of increased Na+/K+ ATPase activity (e.g. beta 2 agonist, theophylline or insulin poisoning), competitive blockade of K+ channels (e.g. barium or chloroquine poisoning), gastrointestinal losses and/or alkalosis. Hyperkalemia follows inhibition of Na+/K+ ATPase activity (e.g. by digoxin), increased uptake of potassium salts, disruption of intermediary metabolism (e.g. cyanide poisoning), activation of K+ channels (e.g. fluoride poisoning), and the presence of acidosis and rhabdomyolysis, particularly if the latter is complicated by renal failure. Hypokalemia results in generalized muscle weakness, paralytic ileus, ECG changes (flat or inverted T waves, prominent U waves, ST segment depression) and cardiac arrhythmias (atrial tachycardia +/- block, AV dissociation, VT, VF). Hyperkalemia is associated with abdominal pain, diarrhea, muscle pain and weakness, ECG changes (tall peaked T waves, ST segment depression, prolonged PR interval, QRS prolongation) and cardiac arrhythmias (VT, VF). Significant disturbances of potassium homeostasis are often unrecognized and may cause considerable morbidity and mortality. Prompt recognition and appropriate treatment of these disturbances could be life-saving.

[Voluntary barium poisoning]

A 45-year-old man attempted to commit suicide by ingesting a large amount of barium. In some hours, he experienced generalized muscle weakness with hypokalaemia, treated by large dose of potassium (440 mmol in the first day). This weakness resulted in difficulties in swallowing and respiratory failure requiring mechanical ventilation. An anuric renal insufficiency started early, requiring haemodialysis for three weeks. It was induced probably by renal toxicity of barium and recovered completely. Later, the patient experienced an extrapyramidal syndrome initiated by tremor and myoclonia. Hypertonia induced a parkinsonian rheumatism, fixing the two hands in an irreducible position. There was also a contracture of superior sphincter of oesophagus, with severe disturbance of deglutition, ending after three months only. MRI study showed a bilateral hypersignal in basal ganglia and thalamus. It remains unknown whether this neurological syndrome was toxic or ischaemic. This patient remained under mechanical ventilation for three months because of disturbances of deglutition. He was discharged to his home at the 6th month. One year later he was still adynamic, but able to carry our rather precise movements.