Epileptic phenomena in bismuth toxic encephalopathy

A review of bismuth-based nanoparticles and their applications in radiosensitising and dose enhancement for cancer radiation therapy

About 50% of cancer patients receive radiation therapy. Despite the therapeutic benefits of this method, the toxicity of radiation in the normal tissues is unavoidable To improve the quality of radiation therapy, in addition to other methods such as IMRT, IGRT, and high radiation dose, nanoparticles have shown excellent potential when ionising radiation is applied to the target volume. Recently, bismuth-based nanoparticles (BiNPs) have become particularly popular in radiation therapy due to their high atomic numbers (Z), high X-ray attenuation coefficient, low toxicity, and low cost. Moreover, it is easy to synthesise in a variety of sizes and shapes. This study aimed to review the effects of the bismuth-based NP and its combination with other compounds, and their potential synergies in radiotherapy, discussed based on their physical, chemical, and biological interactions. Targeted and non-targeted bismuth-based NPs used in radiotherapy as radiosensitizers and dose enhancement effects are described. The results reported in the literature were categorised into various groups. Also, this review has highlighted the importance of bismuth-based NPs in different forms of cancer treatment to find the highest efficiency for applying them as a suitable candidate for various cancer therapy and future clinical applications.

Simultaneous Dual-Contrast Imaging of Small Bowel With Iodine and Bismuth Using Photon-Counting-Detector Computed Tomography: A Feasibility Animal Study

OBJECTIVES

Dual-energy and multienergy computed tomography (DECT/MECT) has the potential to simultaneously visualize two contrast agents in the small bowel: arterial enhancement of iodine in the bowel wall and enteric enhancement of bismuth in the bowel lumen. The purpose of this study was to explore its feasibility in a swine study using a research whole-body photon-counting-detector (PCD) computed tomography (CT) system.

MATERIALS AND METHODS

A phantom study was initially performed to evaluate the quantification accuracy of iodine and bismuth separation from a single PCD-CT scan, which also served as the calibration reference for material decomposition of in vivo swine PCD-CT data. In the animal study, a test bolus scan was first performed to determine the time-attenuation curve for the arterial enhancement, based on which the timing of the PCD-CT dual-contrast scan was determined. A 600 mL homogeneous bismuth-saline solution (180 mL Pepto-Bismol + 420 mL normal saline) was orally administered to the pig using esophageal intubation. Approximately 1 hour after bismuth administration, 40 mL iodine contrast (Omnipaque 350, 5 mL/s) was injected intravenously. A PCD-CT scan was performed 13 seconds after the initiation of the contrast injection to simultaneously capture the arterial enhancement of iodine and the enteric enhancement of bismuth. To provide optimal material separation and quantification, all PCD-CT scans in both phantom and animal studies were operated at 140 kV with 4 energy thresholds of 25, 50, 75, and 90 keV.

RESULTS

Using a generic image-based material decomposition method, the iodine and bismuth samples were successfully delineated and quantified in the phantom images with a root-mean-square-error of 1.32 mg/mL in iodine measurement and 0.64 mg/mL in bismuth measurement. In the pig study, the enhancing bowel wall containing iodine and the small bowel loop containing bismuth were not differentiable in the original PCD-CT images. However, they were clearly distinctive from each other in the iodine- and bismuth-specific images after material decomposition, as reviewed by an abdominal radiologist. In addition, quantitative analysis showed that the misclassification between the two contrast materials was less than 1.0 mg/mL.

CONCLUSIONS

Our study demonstrated the feasibility of simultaneous imaging of iodine and bismuth in small bowel of swine using PCD-CT.

A Short Review on Biomedical Applications of Nanostructured Bismuth Oxide and Related Nanomaterials

In this review, we reported the main achievements reached by using bismuth oxides and related materials for biological applications. We overviewed the complex chemical behavior of bismuth during the transformation of its compounds to oxide and bismuth oxide phase transitions. Afterward, we summarized the more relevant studies regrouped into three categories based on the use of bismuth species: (i) active drugs, (ii) diagnostic and (iii) theragnostic. We hope to provide a complete overview of the great potential of bismuth oxides in biological environments.

Bismuth encephalopathy- a rare complication of long-standing use of bismuth subsalicylate

BACKGROUND

Drugs containing bismuth, although usually safe, may rarely cause neurotoxicity.

CASE PRESENTATION

We describe the case of a 44-year-old woman treated with bismuth subsalicylate for about 20 years, who developed abnormal behaviour and postural instability in two weeks. On examination, she had greyish discoloration of teeth, was confused and presented generalized myoclonic jerks. In the next days, her clinical condition deteriorated, with a reduction in alertness and more exuberant myoclonus. Brain MRI was unremarkable. CSF revealed mild elevation of protein content (47 mg/dL; reference range: 15-45 mg/dL) and elevation of white blood cell count (10/μL). Bismuth levels in urine (375 μg/L), serum (260 μg/L) and CSF (21.4 μg/L) samples were highly above the threshold for toxicity. Following supportive treatment and bismuth discontinuation, she made a full recovery within weeks.

CONCLUSIONS

Although rare, bismuth encephalopathy should be considered in patients presenting with subacute encephalopathy and myoclonus. This encephalopathy can be subacute even after a chronic exposure. Cessation of bismuth can lead to a complete resolution in weeks.

Iatrogenic bismuth toxicity associated with inadvertent long term De-Noltab ingestion

A prolonged course of oral tripotassium dicitratobismuthate (De-Noltab) was administered to an elderly woman. The patient developed extrapyramidal neurological symptoms and subsequently sustained accidental fracture of the right neck of the femur before bismuth toxicity was identified. The parkinsonian features that presented in this patient were thought to be possibly related to the accumulation of bismuth in the basal ganglia as a result of the long term ingestion of tripotassium dicitratobismuthate.

Prolonged treatment with the drug should be discouraged and repeat prescriptions should always be queried.

Bismuth tracing in organotypic cultures of rat hippocampus

Bismuth is known to have neurotoxic side effects in humans and animals. In the 1970s France experienced about a thousand cases of patients suffering from bismuth-induced encephalopathy. Studies suggest that bismuth may provoke a selective degeneration of CA1 pyramidal cells in the organotypic cultures of rat hippocampus. A currently established technique for the histochemical visualization of bismuth was applied on hippocampal tissue cultures allowing the tracing of bismuth in concentrations hitherto not possible. The accumulation and subcellular localization of bismuth is demonstrated in the tissue cultures of rat hippocampus. CA1 pyramidal cells in the rat hippocampus exhibit the highest uptake of bismuth. High bismuth citrate concentrations (10 microM) are able to totally destroy the cytoarchitecture of the hippocampus. At ultrastructural levels bismuth was found to be located exclusively in lysosome-like organelles.

The role of toxins in disorders of mood and affect

This article deals with disorders of mood and the interaction between mood and cognitive function. The various ways in which environmental toxins can lead to disorders of mood are presented, and discussions regarding the neurobiology of mood are presented.

Distribution of bismuth in the brain after intraperitoneal dosing of bismuth subnitrate in mice: implications for routes of entry of xenobiotic metals into the brain

Bismuth (Bi) can produce neurotoxic effects in both humans and animals under certain dosing conditions, but little else is known about the effects of Bi in the brain. In the present study we determined the distribution of Bi in the brains of adult female Swiss-Webster mice 4, 7, 14, 21 and 28 days after a single 2500 mg/kg i.p. injection of Bi subnitrate (BSN), which establishes a depot of absorbable Bi and produces morphological signs of neurotoxicity. Sections of brains were processed by autometallographic (AMG) procedures that produced silver grains at the site of Bi localization (AMGBi). Ventricular dilation was observed in all BSN-dosed mice. Among treated mice there were marked interanimal differences in the absolute amount of AMGBi, but consistent regional and cellular patterns of AMGBi were observed. AMGBi was observed in many cell types in brain regions adjacent to fenestrated blood vessels of the circumventricular organs (CVOs) and olfactory epithelium. Prominent intrasomal AMGBi was observed in nuclei containing large cell bodies, including cranial motor neurons innervating somatic muscle, lateral vestibular and red nucleus and pontine/medullary reticular nuclei. In the hypothalamus, the supraoptic and paraventricular nuclei demonstrated the densest AMGBi. In the cerebellum, Purkinje and granule cell layers with the densest AMGBi were in folia adjacent to the fourth ventricle. In the hippocampus, AMGBi was densest in the fasciola cinerum, polymorph cells of the dentate gyrus, and pyramidal cell layer of the CA3 regions. Neuropil of subcortical auditory nuclei (cochlear nucleus, trapezoid body, lateral lemniscus and nucleus of lateral lemniscus, medial geniculate nucleus and inferior colliculus) had a high density of AMGBi. Among nonneuronal cells, ependyma and meninges lining the ventricular and subarachnoid spaces were labeled extensively. Glial labeling was prominent adjacent to CVOs, in subependymal regions, and in fiber tracts. Presumptive perivascular cells lining large blood vessels had extremely dense AMGBi as early as 4 days after dosing. Smaller blood vessels had moderate AMGBi. However, in regions (e.g. cerebral cortex, striatum) known to have low brain Bi levels after i.p. dosing, vascular deposits accounted for most of the AMGBi. Several animals had foci of AMGBi which suggested that vascular or perivascular aberrations may have contributed to the unusually dense accumulations. The results of the present studies indicate that Bi accumulates predictably in certain regions and cell types. The pattern of regions and cells with the highest AMGBi accumulations is very similar to pattern reported for other xenobiotic metals (i.e. mercury, silver, gold), and supports the hypothesis that these metals may share some mechanisms for entry, distribution and storage in the brain.

Bismuth subsalicylate toxicity as a cause of prolonged encephalopathy with myoclonus

Bismuth subsalicylate preparations are over-the-counter products for gastrointestinal complaints. Bismuth toxicity causes delirium, psychosis, ataxia, myoclonus, and seizures and is reversible over several weeks or months, when bismuth intake is stopped. We report a 54-year-old man with a 6-week history of progressive confusion and memory difficulty and a 2-3-week history of involuntary movements and gait impairment. His encephalopathy was further characterized by marked multifocal myoclonic jerks, coarse postural tremors, postural instability, and gait ataxia. He gradually improved. Extensive toxic, metabolic, and infectious workup demonstrated bismuth toxicity. Spinal tap and brain magnetic resonance scan were normal. Electroencephalography showed bihemispheric slowing. As his encephalopathy cleared, he reported using bismuth subsalicylate long term (daily intake of 8 oz). Bismuth levels 5 weeks after cessation of bismuth were elevated and normalized after 12 weeks. He followed a typical course for bismuth toxicity with subacute progressive encephalopathy and gradual recovery. Creutzfeldt-Jakob was strongly considered due to his rapidly progressive encephalopathy, multifocal myoclonus, and ataxia. Due to its rarity, bismuth toxicity is often overlooked. We hope this presentation will increase recognition of bismuth toxicity. We believe more detailed labeling of bismuth products is needed to avoid similar toxicity from this readily available product.

Extradural application of bismuth iodoform paraffin paste causing relapsing bismuth encephalopathy: a case report with CT and MRI studies

Bismuth iodoform paraffin paste (BIPP) is used in dressings in ear, nose, and throat, dental, and neurosurgical practice. Neurotoxicity due to absorption of bismuth from the BIPP pack is rare. It is preventable and reversible but likely to be fatal if unrecognised. A case of relapsing but reversible toxic encephalopathy due to a large extradural BIPP pack is reported in a 57 year old Caucasian woman, operated on for a huge basal cell carcinoma of the vertex invading the skull and extradural space. Clinical, neuroradiological (CT and MRI), and biochemical studies are presented and discussed in the light of the available literature.

Comparison of plasma bismuth levels after oral dosing with basic bismuth carbonate or tripotassium dicitrato bismuthate

In 20 healthy subjects plasma bismuth concentration was measured after single oral doses of basic bismuth carbonate or tripotassium dicitrato bismuthate. The drugs were administered in the fasted state or immediately after ingestion of a standard breakfast. After basic bismuth carbonate, plasma bismuth rose to concentrations between 0.7 and 2.6 micrograms/L in the fasted state, while after the meal the maximal level was only 1.3 micrograms/L. In contrast to these very low levels after basic bismuth carbonate, the administration of tripotassium dicitrato bismuthate was paralleled by an increase of plasma bismuth to concentrations between 15 and 232 micrograms/L with a mean peak value of 64 +/- 15.3 (S.E.M.) micrograms/L in the fasted state. Postprandial ingestion of tripotassium dicitrato bismuthate attenuated the peak concentrations to 10.9 +/- 6.3 micrograms/L. One subject, however, had a value of 120 micrograms/L. This study demonstrates that basic bismuth carbonate leads to very low plasma bismuth concentrations, which are far below the critical range that might eventually be associated with bismuth neurotoxicity. Therefore this compound can be considered potentially useful for bismuth therapy of gastrointestinal disorders.

Encephalopathy resembling Creutzfeldt-Jakob disease following oral, prescribed doses of bismuth nitrate

A patient given bismuth nitrate in the recommended dose range over 16 months developed panic attacks and a major depressive syndrome and, after 15 months, a myoclonic encephalopathy resembling Creutzfeldt-Jakob disease. He recovered four months after bismuth had been discontinued. Bismuth preparations are becoming popular in the treatment of gastritis; close attention to neurological and psychiatric symptoms seems mandatory.

Bismuth therapy in gastrointestinal diseases

Bismuth therapy has shown efficacy against two major gastrointestinal disorders: peptic ulcer disease and diarrhea. In peptic ulcer disease it is as effective as the H2-receptor antagonists, costs considerably less, and offers a lower rate of relapse. When Helicobacter pylori is implicated, bismuth acts as an antimicrobial agent, suppressing the organism but not eliminating it. In recent studies, bismuth compounds have been used with conventional antibiotics, producing elimination of the organism, histological improvement, and amelioration of symptoms for periods longer than one year. Bismuth subsalicylate has shown modest efficacy in treating traveler's diarrhea and acute and chronic diarrhea in children, and it is effective prophylactically for traveler's diarrhea. An epidemic of neurological toxicity was reported in France in the 1970's with prolonged bismuth treatment, usually bismuth subgallate and subnitrate. Such toxicity has been rare with bismuth subsalicylate and colloidal bismuth subcitrate. However, recent studies have demonstrated intestinal absorption of bismuth (about 0.2% of the ingested dose) and sequestration of this heavy metal in multiple tissue sites, even occurring with conventional dosing over a 6-week period. These findings have inspired recommendations that treatment periods with any bismuth-containing compound should last no longer than 6-8 weeks, followed by 8-week bismuth-free intervals.

Bipp: a case of toxicity?

Ribbon gauze impregnated with bismuth iodoform paraffin paste is a dressing used in both oral and ENT surgery. A case is presented in which it was implicated in increased postoperative morbidity highly suggestive of a toxic state.

Pharmacokinetics and toxicity of bismuth compounds

Inorganic bismuth salts are poorly soluble in water: solubility is influenced by the acidity of the medium and the presence of certain compounds with (hydr)oxy or sulfhydryl groups. The analysis of bismuth in biological material is not standardised and is subject to large variation; it is difficult to compare data from different studies, and older data should be approached with caution. The normal concentration of bismuth in blood is between 1 and 15 micrograms/L, but absorption from oral preparations produces a significant rise. Distribution of bismuth in the organs is largely independent of the compound administered or the route of administration: the concentration in kidney is always highest and the substance is also retained there for a long time. It is bound to a bismuth-metal binding protein in the kidney, the synthesis of which can be induced by the metal itself. Elimination from the body takes place by the urinary and faecal routes, but the exact proportion contributed by each route is still unknown. Elimination from blood displays multicompartment pharmacokinetics, the shortest half-life described in humans being 3.5 minutes, and the longest 17 to 22 years. A number of toxic effects have been attributed to bismuth compounds in humans: nephropathy, encephalopathy, osteoarthropathy, gingivitis, stomatitis and colitis. Whether hepatitis is a side effect, however, is open to dispute. Each of these adverse effects is associated with certain bismuth compounds. Bismuth encephalopathy occurred in France as an epidemic of toxicity and was associated with the intake of inorganic salts including bismuth subnitrate, subcarbonate and subgallate. In the prodromal phase patients developed problems in walking, standing or writing, deterioration of memory, changes in behaviour, insomnia and muscle cramps, together with several psychiatric symptoms. The manifest phase started abruptly and was characterised by changes in awareness, myoclonia, astasia and/or abasia and dysarthria. Patients recovered spontaneously after discontinuation of bismuth. Intestinal lavage, forced diuresis and haemodialysis have been tried without positive effects on the clinical condition of the patient or on blood bismuth concentration, and the use of dimercaprol as an antidote has produced reports of both positive and negative findings. To confirm the diagnosis of bismuth encephalopathy, it is essential to find elevated bismuth concentrations in blood, plasma, serum or CSF. A safety level of 50 micrograms/L and an alarm level of 100 micrograms/L have been suggested in the past, but no proof is available to support the choice of these levels.(ABSTRACT TRUNCATED AT 400 WORDS)

Divalent transition-metal ions (Cu2+ and Zn2+) in the brains of epileptogenic and normal mice

The concentrations of Cu2+ and Zn2+ in 3 strains of mice were determined spectrophotometrically. The brain of the inborn audiogenic mouse (DBA/2J) contains higher levels of Zn2+ and Cu2+ than those found in the normal mouse (CBA/Ca or Parkes). Small differences in the metallic content in the whole brains of audiogenic and normal mice are accentuated in the hippocampus and the colliculus.

Experimentally induced susceptibility to audiogenic seizure

By injecting metal ions and pyridoxal-5'-phosphate, we made the normal mouse prone to sound-induced epilepsy. We showed that the levels of glutamate and aspartate in its inferior colliculus were elevated and the concentration of gamma-aminobutyrate was lowered. The time course of audiogenic susceptibility after the treatment was closely mirrored by changes in the concentrations of glutamate, aspartate, and gamma-aminobutyrate in the inferior colliculus.

Antidotes for acute bismuth intoxication

Nine chelating agents were tested as antidotes for acute bismuth intoxication in mice. Of these, those with sulfhydryl groups, adjacent aromatic hydroxy groups or appropriately positioned phosphonate groups proved themselves to be effective antidotes. Of the compounds currently approved for therapeutic use, D-penicillamine was the most effective.