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Lathyrism and konzo are two similar self-limiting cortical motor neuron disorders characterized by spastic disability of the lower extremities and, in severe cases, with disability in the upper extremities and even (in konzo only) pseudobulbar dysfunction. They are caused by prolonged and almost exclusive dietary dependence on grass pea (lathyrism) or insufficiently processed bitter cassava (konzo), with poor nutritional state a significant risk factor and excessive exercise an apparent precipitating factor. Only lathyrism has been partially modeled in laboratory primates. Experimental studies suggest these toxic neurodegenerative disorders are primary neuronopathies dominated by bilateral involvement of upper motor neurons and their axonal projections. Those cortical motor neurons with the longest axonal projections seem to be most vulnerable, possibly because they have the largest dendritic tree and available glutamate receptors that are likely targets of the culpable grass pea neurotoxin (BOAA) and the neurotoxic cassava metabolites (SCN, OCN ti]Onset of lathyrism and konzo is often abrupt, and some degree of clinical improvement is characteristic before the clinical signs stabilize into a pure form of spastic para/ tetraparesis. Clinical progression may occur with continued intake of the offending foodstuff. Prolonged lower-level intake of cassava has been associated with distinct neurological syndromes in adults, notably an ataxic (myelo)neuropathy for which OCN is a likely etiological factor.

The desert mouse (Pseudomys desertor) is one of the most common and widespread native rodent species across arid and semiarid Australia. The species occurs in a variety of habitats and like many arid-zone rodents, its distribution and abundance is known to fluctuate with environmental conditions. Following the capture of a suspected specimen of P. desertor outside the current known range of the species, we used molecular-based methods to confirm the specimen’s identification as P. desertor. This note presents a record of the species north of Dalwallinu, Western Australia, which represents a significant range extension for the species of 324 km from the nearest confirmed record.

Lathyrism is a disorder of the central motor system, induced by heavy consumption of the grass-pea, Lathyrus sativus an environmentally tolerant legume containing the neurotoxic excitatory amino acid beta-N-oxalylamino-L-alanine (BOAA). A complete door-to-door resurvey of the Dembia and Fogera regions of northwestern Ethiopia, areas endemic for lathyrism, revealed an estimated mean disease prevalence of 0.6%-2.9%. Most patients developed the disease in the epidemic of 1976/77, although new cases appear to have occurred with an estimated mean annual incidence of 1.7:10,000. Production and consumption of grass-pea is increasing in Ethiopia, making attempts to develop low-BOAA strains to prevent lathyrism increasingly important.

beta-N-Oxalylamino-L-alanine (BOAA) and beta-N-methylamino-L-alanine (BMAA) are chemically related excitant amino acids isolated from the seed of Lathyrus sativus (BOAA) and Cycas circinalis (BMAA), consumption of which has been linked to lathyrism (an upper motor neuron disorder) and Guam amyotrophic lateral sclerosis (ALS), respectively. Both diseases are associated with degeneration of motor neurons. Experimentally, single doses of BOAA or BMAA induce seizures in neonatal mice and postsynaptic neuronal oedema and degeneration in explants of mouse spinal cord and frontal cortex. Preliminary studies show that these behavioural and pathological effects are differentially blocked by glutamate-receptor antagonists. In macaques, several weeks of daily oral doses of BOAA produce clinical and electrophysiological signs of corticospinal dysfunction identical to those seen in comparably well-nourished animals receiving a fortified diet based on seed of Lathyrus sativus. By contrast, comparable oral dosing with BMAA precipitates tremor and weakness, bradykinesia and behavioural changes, with conduction deficits in the principal motor pathway. BOAA and BMAA (or a metabolite thereof) are the first members of the excitotoxin family to have been shown to possess chronic motor-system toxic potential. These observations provide a rational basis for searching for comparable endogenous neurotoxins in sporadic and inherited forms of human motor neuron disease.

The aromatic hydrocarbon 1,2-diacetylbenzene (1,2-DAB) is a protein-reactive gamma-diketone metabolite of the neurotoxic solvent 1,2-diethylbenzene (1,2-DEB). The effect of neurotoxic 1,2-DAB and its non-neurotoxic isomer 1,3-DAB has been studied on motor proteins and cytoskeletal proteins of rat spinal cord (SC). For in vitro studies, SC slices were incubated with 1, 2, 5, 10 mM of DAB isomers for 30 min at 37 degrees C. For in vivo studies, rats received (i.p.) 20 mg/kg/day of 1,2-DAB or 1,3-DAB, or vehicle (2% acetone in saline), 5 days a week for 2 weeks. Spinal cord and sciatic nerve proteins were subjected to Western blotting using monoclonal mouse antibodies to NF-M, kinesin, dynein, and tau. Proteins were quantified and paired mean comparisons performed to assess concentration-dependent changes in native protein bands. In vitro, 1,2-DAB produced a concentration-dependent decrease of motor and cytoskeletal proteins. While dynein and tau appeared similarly affected by 1,2-DAB, kinesin was most affected by the toxicant. In vivo, 1,2-DAB affected motor and cytoskeletal proteins of sciatic nerves and spinal cord differentially. In general, sciatic nerve proteins were much more affected than spinal cord proteins. The results show that motor proteins that drive axonal transport anterogradely (kinesin) and retrogradely (dynein), cytoskeletal protein NF-M, which is slowly transported in the anterograde direction, and microtubule-associated protein, tau, which is involved in axonal transport, are differentially impacted by 1,2-DAB. By contrast, non-neurotoxic isomer 1,3-diacetylbenzene (1,3-DAB), had no adverse effect on neural proteins either in vitro or in vivo. 2D-Differential in gel electrophoresis (2D-DIGE) of sciatic nerves from neurotoxic 1,2-DAB and non-neurotoxic 1,3-DAB treated rats revealed 197 and 304 protein spots, respectively.

Lathyrism and konzo are two similar self-limiting cortical motor neuron disorders characterized by spastic disability of the lower extremities and, in severe cases, with disability in the upper extremities and even (in konzo only) pseudobulbar dysfunction. They are caused by prolonged and almost exclusive dietary dependence on grass pea (lathyrism) or insufficiently processed bitter cassava (konzo), with poor nutritional state a significant risk factor and excessive exercise an apparent precipitating factor. Only lathyrism has been partially modeled in laboratory primates. Experimental studies suggest these toxic neurodegenerative disorders are primary neuronopathies dominated by bilateral involvement of upper motor neurons and their axonal projections. Those cortical motor neurons with the longest axonal projections seem to be most vulnerable, possibly because they have the largest dendritic tree and available glutamate receptors that are likely targets of the culpable grass pea neurotoxin (BOAA) and the neurotoxic cassava metabolites (SCN, OCN ti]Onset of lathyrism and konzo is often abrupt, and some degree of clinical improvement is characteristic before the clinical signs stabilize into a pure form of spastic para/ tetraparesis. Clinical progression may occur with continued intake of the offending foodstuff. Prolonged lower-level intake of cassava has been associated with distinct neurological syndromes in adults, notably an ataxic (myelo)neuropathy for which OCN is a likely etiological factor.

Background Treatment of medically trivial disorders by intravenous drug infusion has been widespread in China. Children with common colds are routinely given antibiotics intravenously, and students faced with stressful exams receive amino acids intravenously. Adverse outcomes from intravenous infusion reached 0·74% in one study. In December 2011, China reported its citizens consumed on average 138 g antibiotics annually, ten-times the per capita use in the USA. 70% of inpatients in Chinese hospitals receive antibiotics compared with a maximum of 30% recommended by WHO. Overall, three times as many Chinese patients are prescribed penicillin compared with the international norm. Explanations for high rates of intravenous infusion usage range from market-based reforms rewarding physicians, hospitals, and manufacturers, to overwhelming patient demand. The aim of this study was to assess patient demand for intravenous infusion. Methods We collected qualitative information from participants in one health centre and one university: respectively, the Qilidian Community Health Service Center, Runzhou, Zhenjiang and Jiangsu University, Zhenjiang, Jiangsu Province, both of which reviewed and approved the project. We utilised the method of purposive sampling (a method used in the study of cultural phenomena) by selecting persons with knowledge or experience with intravenous infusion. Patients, health providers, and medical students served as respondents, each of whom provided informed verbal consent before discussing their views and experience with intravenous infusion (primary outcomes). People who were acutely sick and those unable to communicate in Mandarin or Cantonese were excluded. We observed the practice of and interviewed 30 patients (inpatients and outpatients), five nurses (including three head nurses), three pharmacists, 11 medical doctors and directors, and more than ten medical students. These participants were considered to form a representative group of stakeholders from which to obtain information for use in the design of a future formal research study. Findings About 30% of outpatients received intravenous infusions, which is substantially lower than rates of up to 96% reported in Guangdong Province. Patients receiving drugs intravenously typically presented with illnesses of varying severity: childhood pneumonia, weakness, diarrhoea, a few days' history of coughing or fever, tonsillitis, and dizziness secondary to low blood pressure. Intravenous treatment spanned 2 h/day for 1–5 days depending on the drug. Despite this time commitment, patient preference for intravenous treatment was dominated by the desire for rapid recovery driven by the need to return to school (to maintain academic competitiveness) or work (to maintain an income stream). These considerations surmounted patient perceptions of procedural risk, although needle puncture, unpleasant sensations, nausea, fainting, bruising, rash, and even antibiotic resistance, were acknowledged on occasion. The cost of intravenous drug delivery was considered acceptable. Doctors described huge patient loads, insufficient time to discuss the benefits and risks of intravenous infusion, and potential physician endangerment for failing to comply with a patient's wishes. Interpretation Although overuse of intravenous therapy might cause adverse outcomes, including the potential for antibiotic resistance, patient perception of rapid therapeutic benefit still dominates demand. The public has been urged by health departments to use intravenous infusion as a last resort, and not the norm, yet this risky practice continues. These preliminary observations provide the foundation to design a formal research-education study of stakeholder understanding of the use, value, and risks of intravenous infusion in primary healthcare settings. Funding Jiangsu University and OHSU Foundation Global Health Center Fund.

This note shows that there is an error in the mathematical argument deployed by Ford et al. (1992). Once this is corrected, we see that, remarkably, the standard opportunity cost based weighting system remains appropriate even in the face of non-neutral technical change.

The chromogenic and neurotoxic gamma-diketone 1,2-diacetylbenzene (1,2-DAB), but not its isomer 1,3-DAB, induces blue discoloration of tissues and urine, clustering of axonal microtubules and proximal neurofilament-filled axonal swellings in rodents. The remarkable chromogenic property of 1,2-DAB, a monocyclic aromatic hydrocarbon, arises from reaction with lysine residues of proteins and formation of dimeric and polymeric derivatives. Tetralin, a dicyclic solvent structurally related to acetyl ethyl tetramethyl tetralin, a chromogenic and neurotoxic agent, reportedly induces excretion of green urine, and causes neurological disturbances in humans. Monocyclic aromatic 1,2,4-triethylbenzene (1,2,4-TEB), but not its isomer 1,3,5-TEB, is also reportedly chromogenic and induces neurophysiological deficits in rodents consistent with axonal neuropathy, but without neuropathological confirmation. We treated 12-week-old C57Bl/6 mice by gavage with 300, 600, or 900 mg/kg/day 1,2,4-TEB, or equivalent doses of 1,3,5-TEB, 3 days/week, for up to 12 weeks, or intraperitoneally with 400 mg/kg/day tetralin, or 50 or 100 mg/kg/day of its alpha-tetralol analogue, 5 days/week, for up to 5 weeks. Animals treated with 1,2,4-TEB, but not 1,3,5-TEB, tetralin or alpha-tetralol, developed hind limb weakness, excreted greenish urine, and showed 1,2-DAB-like neuropathology. These findings support the hypothesis that 1,2-spaced ethyl (or acetyl) moieties on a benzene ring of hydrocarbons are required for hydrocarbons to induce chromogenic changes and proximal giant neurofilamentous axonopathy. Key molecular targets of these compounds likely reside in the axon where they serve to maintain normal cytoskeletal organization.

Examination of blood films as part of a study to assess the health status of the southern brown bandicoot Isoodon obesulus (Shaw) in Western Australia revealed the gamonts of a haemogregarine parasite in some samples, the first to be recognised in a bandicoot in this state. Light microscope morphological characteristics and partial sequence of the 18S rRNA gene were used to describe these organisms. Morphological characters did not differentiate the organism in the current study from previously reported Hepatozoon peramelis (Welsh & Dalyell, 1909). Phylogenetic analysis has not previously been reported for any species of Hepatozoon from Australian marsupials and consequently could not be used to confirm the identity of the organism in the current study as that described in the 1900s. If this organism is H. peramelis, then it has a wide distribution, being found in three species of bandicoot, in western and eastern Australia and the in island state of Tasmania.

Lathyrus sativus (grass pea) is a high-yielding, drought-resistant legume consumed as a food in Northern India and neighboring countries as well as in Ethiopia. Its development into an important food legume, however, has been hindered by the presence of the neurotoxin - beta-N-oxalyl-L-alpha,beta-diaminopropionic acid (beta-ODAP) in seeds which, if consumed in large quantities for prolonged periods, can cause irreversible paralysis. Recently, some low-toxin lines have been developed that may prove safe for both animal and human foods. Cultivation of L. sativus should thus be considered in suitable regions because the demand for legume animal feed protein products is expected to increase. This paper addresses advances in understanding L. sativus from the perspective of its taxonomy, genetics, ecology, chemistry, nutrition, medicine, biology and for animal nutrition.

Background: In response to Gulf War veterans’ concerns of high rates of ALS, this investigation sought to determine if Gulf War veterans have an elevated rate of ALS. Methods: A nationwide epidemiologic case ascertainment study design was used to ascertain all occurrences of ALS for the 10-year period since August 1990 among active duty military and mobilized Reserves, including National Guard, who served during the Gulf War (August 2, 1990, through July 31, 1991). The diagnosis of ALS was confirmed by medical record review. Risk was assessed by the age-adjusted, average, annual 10-year cumulative incidence rate. Results: Among approximately 2.5 million eligible military personnel, 107 confirmed cases of ALS were identified for an overall occurrence of 0.43 per 100,000 persons per year. A significant elevated risk of ALS occurred among all deployed personnel (RR = 1.92; 95% CL = 1.29, 2.84), deployed active duty military (RR = 2.15, 95% CL = 1.38, 3.36), deployed Air Force (RR = 2.68, 95% CL = 1.24, 5.78), and deployed Army (RR = 2.04; 95% CL = 1.10, 3.77) personnel. Elevated, but nonsignificant, risks were observed for deployed Reserves and National Guard (RR = 2.50; 95% CL = 0.88, 7.07), deployed Navy (RR = 1.48, 95% CL = 0.62, 3.57), and deployed Marine Corps (RR = 1.13; 95% CL = 0.27, 4.79) personnel. Overall, the attributable risk associated with deployment was 18% (95% CL = 4.9%, 29.4%). Conclusions: Military personnel who were deployed to the Gulf Region during the Gulf War period experienced a greater post-war risk of ALS than those who were deployed to the Gulf.

The purpose of this study was to investigate the presence of the anaerobic intestinal spirochetes Brachyspira aalborgi and Brachyspira pilosicoli in the feces of captive nonhuman primates ( n = 35) from 19 species housed at the Zoological Gardens, Perth, Western Australia. Both spirochete species are known to infect human beings. DNA was extracted from freshly collected feces with a commercially available QIAamp DNA stool minikit and subjected to PCR protocols amplifying portions of the 16S rRNA genes of the two spirochete species. The feces were also subjected to selective culture for the spirochetes. Subsequently, feces from 62 other captive animals or birds representing 39 species at the zoo were examined by PCR to determine whether they were reservoirs of infection. Six fecal samples from individuals from four primate species (two vervet monkeys, two Tonkean macaques, one Japanese macaque, and one hamadryas baboon) tested positive in the B. aalborgi PCR. B. aalborgi was not detected by PCR in any of the other animal or bird species tested, and B. pilosicoli was not detected in the primates or any of the other animals or birds. B. aalborgi was isolated from both PCR-positive vervet monkeys. This is the first time that B. aalborgi has been isolated from nonhuman primates and the first time that it has been isolated from the feces of any species.

Succinic dehydrogenase in mouse cortical explant cultures was inhibited by 3-nitropropionic acid (3-NPA). ATP concentrations declined upon application of 3-NPA. At 4 h, ATP levels of cultures treated with 3-NPA alone were no different from those in cultures treated additionally with MK-801 (20 microM), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX; 10 microM) or a combination thereof. However, MK-801 and MK-801 plus CNQX mitigated morphological lesions caused by 3-NPA. CNQX alone did not influence the extent of morphological damage. In conclusion, MK-801, at concentrations which were neuroprotective against 3-NPA lesions in cortical explant cultures, did not modify 3-NPA dependent decreases in cellular ATP levels. These data indicate that the neuroprotective effects of glutamate receptor antagonists in this model are probably receptor mediated and do not involve effects on cellular metabolism.

Populations in fragmented urban remnants may be at risk of genetic erosion as a result of reduced gene flow and elevated levels of inbreeding. This may have serious genetic implications for the long-term viability of remnant populations, in addition to the more immediate pressures caused by urbanisation. The population genetic structure of the generalist skink Ctenotus fallens was examined using nine microsatellite markers within and among natural vegetation remnants within a highly fragmented urban matrix in the Perth metropolitan area in Western Australia. These data were compared with samples from a large unfragmented site on the edge of the urban area. Overall, estimates of genetic diversity and inbreeding within all populations were similar and low. Weak genetic differentiation, and a significant association between geographic and genetic distance, suggests historically strong genetic connectivity that decreases with geographic distance. Due to recent fragmentation, and genetic inertia associated with low genetic diversity and large population sizes, it is not possible from these data to infer current genetic connectivity levels. However, the historically high levels of gene flow that our data suggest indicate that a reduction in contemporary connectivity due to fragmentation in C. fallens is likely to result in negative genetic consequences in the longer term.

Background: During the 1991 Gulf War, some Allied troops were potentially exposed to chemical warfare agents as the result of the detonation of Iraqi munitions at Khamisiyah. Methods: In 1999, we conducted a computer-assisted telephone survey of 2918 Gulf War veterans from Oregon, Washington, California, North Carolina, and Georgia to evaluate the prevalence of self-reported medical diagnoses and hospitalizations among this potentially exposed population and among comparison groups of veterans deployed and nondeployed to the Southwest Asia theater of operations. Results: Troops reported to be within 50 kilometers of the Khamisiyah site did not differ from other deployed troops on reports of any medical conditions or hospitalizations in the 9 years following the Gulf War. Hospitalization rates among deployed and nondeployed troops did not differ. Deployed troops were significantly more likely to report diagnoses of high blood pressure (odds ratio [OR]=1.7); heart disease (OR=2.5); slipped disk or pinched nerve (OR=1.5); post-traumatic stress disorder (OR=14.9); hospitalization for depression (OR=5.1); and periodontal disease (OR=1.8) when compared to nondeployed troops. There was a trend for deployed veterans to report more diagnoses of any cancer (OR=3.0). Conclusions: These findings do not provide evidence of any long-term health effect associated with exposure to the detonation of chemical warfare agents, but support findings from other investigations of increased morbidity among deployed troops. The prevalence of cancer among this population of deployed troops merits ongoing attention.

The gamma-diketone analogs 1,2-diacetylbenzene (1,2-DAB) and 2,5-hexanedione (2,5-HD), but not the delta-diketone 1,3-diacetylbenzene (1,3-DAB) or the beta-diketone 2,4-hexanedione, induce neuropathological changes in the rodent central and peripheral nervous systems. The molecular targets of these neurotoxic aromatic and aliphatic gamma-diketones, and of their nonneurotoxic structural analogs and ninhydrin, are examined by assessing their differential reactivity with neural and nonneural amino acids and proteins in vitro and in vivo. Whereas 1,2-DAB is chromogenic and forms polymers with amino acids (notably lysine) and proteins (especially lysine-rich proteins), 1,3-DAB lacks these properties. Ninhydrin forms a chromophore without evidence of protein polymerization. 1,2-DAB preferentially targets neurofilament over microtubule protein in vitro and in situ. Based on protein reactivity, 1,2-DAB is three orders of magnitude more reactive than 2,5-HD. Lysine-rich neurofilament protein subunits NF-H and NF-M are more susceptible than lysine-poor NF-L and beta-tubulin to 1,2-DAB. These observations correlate with the development of proximal (1,2-DAB) and distal (2,5-HD) neurofilament-filled axonal swellings and segregated intact microtubules observed during systemic treatment with aromatic and aliphatic gamma-diketones.

Many factors have been considered as possible causes of the unexplained illness reported by veterans of the Gulf War (GW). In this study, we report an analysis of risk factors and unexplained illness in a population-based sample of GW veterans who underwent clinical evaluation. Multiple risk factors were compared in 241 veterans who met criteria for unexplained illness and 113 healthy controls. Results suggest that GW unexplained illness is most highly associated with combat conditions, heat stress, and having sought medical attention during the GW. When controlling for multiple simultaneous exposures during the GW, interactions around pyridostigmine bromide, insecticides and repellents, and stress were not significant. These results indicate that most unexplained illness in GW veterans cannot be explained by neurotoxic effects of exposures to chemicals that inhibit cholinesterase activity.

Objectives To test for any temporal association of Nodding syndrome with wartime conflict, casualties and household displacement in Kitgum District, northern Uganda. Methods Data were obtained from publicly available information reported by the Ugandan Ministry of Health (MOH), the Armed Conflict Location & Event Data (ACLED) Project of the University of Sussex in the UK, peer-reviewed publications in professional journals and other sources. Results Reports of Nodding syndrome began to appear in 1997, with the first recorded cases in Kitgum District in 1998. Cases rapidly increased annually beginning in 2001, with peaks in 2003–2005 and 2008, 5–6 years after peaks in the number of wartime conflicts and deaths. Additionally, peaks of Nodding syndrome cases followed peak influxes 5–7 years earlier of households into internal displacement camps. Conclusions Peaks of Nodding syndrome reported by the MOH are associated with, but temporally displaced from, peaks of wartime conflicts, deaths and household internment, where infectious disease was rampant and food insecurity rife.

Several widely used aromatic hydrocarbon solvents reportedly induce blue-green discoloration of tissues and urine in animals and humans. The chomophore has been proposed to result from a ninhydrin-like reaction with amino groups in proteins. The present study examines the neurotoxic property of 1,2-diacetylbenzene (1,2-DAB), the active metabolite of the chromogenic and neurotoxic aromatic solvent 1,2-diethylbenzene. Rats treated with 1,2-DAB, but not with the nonchromogenic isomer 1,3-DAB or with ninhydrin developed blue discoloration of internal organs, including the brain and spinal cord. Only 1,2-DAB induced limb weakness associated with nerve fiber changes, which were most prominent in spinal cord and spinal roots. Changes began with the formation of proximal, neurofilament-filled axonal swellings of the type seen after treatment with 3,4-dimethyl-2,5-hexanedione, a potent derivative of the active metabolite of the neurotoxic aliphatic hydrocarbon solvents n-hexane and methyl n-butyl ketone. These compounds are metabolized to a gamma-diketone that forms pyrroles with target proteins, such as neurofilament proteins. A comparable mechanism is considered for 1,2-DAB, an aromatic gamma-diketone.

An ideal classification of neurotoxic substances should link the vulnerable target of chemical attack to alterations in neural function. There is little basis for classifying agents based on their common use or physico-chemical properties. Outlined in this article are the principal cellular targets of substances that perturb the nervous system structure and function.

Idiopathic Parkinson’s disease (PD) and related neurodegenerative disorders are characterized clinically by insidious onset and relentless advance that presumably reflect an ever-increasing loss of neuronal connectivity. Disconnection of neural pathways may result from primary degeneration of dendrites, neuronal perikarya, axons, or nerve terminals. Specificity of neuronal damage appears to be linked to factors such as: the structure and potency of the agent; the architecture, size, and activity of the neuronal pathway; and the presence of neuronal receptors and transporters for neurotransmitters and other molecules. Foreign substances that perturb axonal transport are associated with distal, retrograde (dying-back) degeneration, while those that interfere with glutamate neurotransmission may compromise dendritic integrity and trigger neuronal degeneration. Neither type of agent appears to be able to induce a progressive neuronal disease, a property that might be associated with substances that up-regulate the neuronal response to glutamate neurotransmission by persistently interfering with nucleic acid function. Discovery of environmental factors that act on normal or susceptible genotypes to trigger PD and related neurodegenerative disorders may open the way for disease prevention.

There is increasing evidence that defects in mitochondrial energy metabolism play an important role in the pathogenesis of major human neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), Huntington’s disease (HD), amyotrophic lateral sclerosis (ALS), and dystonia. AD is the most common form of dementia that occurs in the elderly and may result from various genetic and environmental influences (1). A genetic defect arising from mitochondrial DNA (mt DNA) that is inherited solely from the mother could account for defects in the electron transport chain and contributes to deficits in energy levels in AD (2–4). Recent work has shown that mutations in cytochrome c oxidase may impair energy metabolism that may lead to a cascade of events resulting in AD. PD is characterized clinically by bradykinesia, rigidity, and tremors and pathologically by the damage of dopaminergic neurons in the substantia nigra. Some forms of PD are inherited and other forms may be triggered by environmental agents. A significant decrease of mitochondrial complex I activity has been observed in the substantia nigra of Parkinson’s patients (5–8).

It is generally agreed that ALS/PDC is triggered by a disappearing environmental factor peculiar to the lifestyle of people of the western Pacific (i.e., Guam, Irian Jaya, Indonesia, and the Kii Peninsula of Japan). A strong candidate is the cycad plant genotoxin cycasin, the beta-D-glucoside of methylazoxymethanol (MAM). We propose that prenatal or postnatal exposure to low levels of cycasin/MAM may damage neuronal DNA, compromise DNA repair, perturb neuronal gene expression, and irreversibly alter cell function to precipitate a slowly evolving disease ("slow-toxin" hypothesis). In support of our hypothesis, we have demonstrated the following: 1. DNA from postmitotic rodent central nervous system neurons is particularly sensitive to damage by MAM. 2. MAM reduces DNA repair in human and rodent neurons, whereas DNA-repair inhibitors potentiate MAM-induced DNA damage and toxicity in mature rodent nervous tissue. 3. Human neurons (SY5Y neuroblastoma) that are deficient in DNA repair are susceptible to MAM-induced cytotoxicity and DNA damage, whereas overexpression of DNA repair in similar cells is protective. 4. MAM alters gene expression in SY5Y human neuroblastoma cells and, in the presence of DNA damage and reduced DNA repair, enhances glutamate-modulated expression of tau mRNA in rat primary neurons; the corresponding protein (TAU) is elevated in ALS/PDC and Alzheimer's disease. These findings support a direct relationship between MAM-induced DNA damage and neurotoxicity and suggest the genotoxin may operate in a similar manner in vivo. More broadly, a combination of genotoxin-induced DNA damage (via exogenous and/or endogenous agents) and disturbed DNA repair may be important contributing factors in the slow and progressive degeneration of neurons that is characteristic of sporadic neurodegenerative disease. Preliminary studies demonstrate that DNA repair is reduced in the brain of subjects with western Pacific ALS/PDC, ALS, and Alzheimer's disease, which would increase the susceptibility of brain tissue to DNA damage by endogenous/exogenous genotoxins. Interindividual differences in the extent of prior exposure to DNA-damaging agents and/or the efficiency of its repair might produce population variety in the rate of damage accumulation and explain the susceptibility of certain individuals to sporadic neurodegenerative disease. Studies are underway using DNA-repair proficient and deficient neuronal cell cultures and mutant mice to explore gene-environment interplay with respect to MAM treatment, DNA damage, and DNA repair, and the age-related appearance of neurobehavioral and neuropathological compromise.

Concerns that chemical warfare (CW) agents themselves or in combination with other chemicals may cause long-term damage to nerve and muscle are reviewed and discussed. Experiments on mice and hens underway with agent GA and pyridostigmine bromide (PB) and their effects (either separately or together) are presented.

Sodium cyanate, a neurotoxic chemical in rodents, primates and humans, is implicated in neurodegenerative disorders in protein-deficient populations subsisting in parts of Africa on the cyanogenic plant cassava. The molecular and cellular mechanisms of cyanate neurotoxicity are not understood. This study investigates the effect of sodium cyanate on glutathione (GSH) homeostasis in rodent brain and liver in vitro and in vivo. GSH levels in mouse brain were rapidly, time- and dose-dependently decreased following intraperitoneal administration of 100, 200 or 300 mg/kg sodium cyanate. By contrast, GSH disulfide (GSSG) levels were increased and GSH/GSSG ratios were decreased in a dose-dependent manner in rat brain. Sodium cyanate depleted GSH levels in all regions of mouse brain. Brain glutathione reductase activity was dose-dependently inhibited, while glutathione peroxidase activity was not affected by sodium cyanate. The disruption of GSH homeotasis, as evidenced by reduced tissue GSH/GSSG ratios, likely results from cyanate-induced inhibition of glutathione reductase activity. The results of this study suggest that cyanate neurotoxicity, and perhaps cassava-associated neurodegenerative diseases, are mediated in part by disruption of glutathione homeostasis in neural tissue.

Pyridostigmine bromide (PB) promotes and then silences cholinergic muscle activity, and disrupts the junctional regions of muscle fibers and associated nerve terminals, in organotypic mouse spinal cord-muscle cultures continuously treated with low concentrations of the drug for up to 14 days. Spontaneous muscle activity is restored within 1 week of drug removal.

Ancient DNA is becoming increasingly recognised as a tool in conservation biology to audit past biodiversity. The widespread loss of Australian biodiversity, especially endemic mammal populations, is of critical concern. An extreme example occurred on Depuch Island, situated off the north-west coast of Western Australia, where an unidentified species of rock-wallaby (Petrogale sp.) became extinct as a result of predation by red foxes. Two potential candidate species, Petrogale lateralis and P. rothschildi, both have ranges adjacent to Depuch Island, making identification based on geography difficult. A museum bone (one of the only surviving Depuch Island specimens) was subjected to standard ancient DNA analyses and procedures. Mitochondrial DNA cytochrome b and hypervariable control region were targeted for species identification. Ancient DNA was successfully recovered from the bone: 200 base pairs (bp) of control region and 975 bp of the cytochrome b gene. Bayesian phylogenetic analyses were employed to model the Depuch Island rock-wallaby DNA sequences together with sequences of other rock-wallaby taxa from GenBank. Evidence suggests that of the two Petrogale lateralis subspecies proposed to have inhabited Depuch Island, Petrogale lateralis lateralis was identified as the most likely. The identification of the Depuch Island rock-wallaby population may assist in the reintroduction of an insurance population of Petrogale lateralis lateralis, which is becoming increasingly threatened on mainland Australia.

beta-N-Oxalylamino-L-alanine (L-BOAA), a non-protein neuroexcitatory amino acid present in the seeds of Lathyrus sativus (chickling or grass pea), is known to produce its neurotoxic effects by overstimulation of non-N-methyl-D-aspartate receptors, especially alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) receptors, at micromolar concentrations. It has recently been reported that L-BOAA selectively inhibits mitochondrial enzyme NADH-dehydrogenase (NADH-DH) in brain slices at subpicomolar concentrations. The present study finds that up to 4 mM concentrations of pure L-BOAA fail to inhibit NADH-DH activity in mouse brain homogenate and isolated brain mitochondria. Two known inhibitors (rotenone and 1-methyl-4-phenylpyridinium ion, MPP+) of this mitochondrial enzyme produced significant inhibition under identical conditions. NADH-DH inhibition was also not observed in the homogenate or mitochondria from the brains of animals systemically treated with convulsive doses of L-BOAA. Some inhibition (20-37%) of NADH-DH activity was observed in mouse brain slices incubated with 100-1,000 microM concentrations of L-BOAA for 1 h at 37 degrees C in an atmosphere of 95% O2 and 5% CO2, but the inhibition was nonselective, because the activity of another mitchondrial enzyme, succinic dehydrogenase, was similarly inhibited by L-BOAA. These results are in contrast with the report that L-BOAA inhibits mitochondrial NADH-DH selectively at subpicomolar concentrations. We suggest the observed nonselective NADH-DH inhibition in mouse brain slices treated with L-BOAA is caused by neuronal damage through an excitotoxic mechanism.

Electrophysiological and receptor binding techniques were used to determine whether the neurotoxin β-N-4-methylamino-l-alanine (BMAA), a monocarboxylic amino acid, can act at the strychnine-insensitive glycine modulatory site to modify the activity of N-methyl-d-aspartate receptors. dl-BMAA but not l-BMAA reversibly potentiated the amplitude of NMDA-activated currents. Neither dl-BMAA nor l-BMAA were able independently to activate currents. The reversal potential and the potential-dependence of the amplitude were not affected by dl-BMAA. The dl-BMAA effect was reversibly antagonized by 7-chlorokynurenic acid. Concentration jump experiments showed that the time course of the “off” response of NMDA-activated currents in the presence of dl-BMAA is faster than in the presence of glycine, suggesting that dl-BMAA dissociates from the receptor more rapidly than glycine. dl-BMAA produced a concentration-dependent displacement of [3H]glycine binding which was additive with that of 7-chlorokynurenic acid. These data indicate that d-BMAA could act as a stereospecific modulator of NMDA receptor function by acting as an agonist at the strychnine-insensitive glycine modulatory site of the NMDA receptor.

Two non-protein amino acids of Lathyrus sativus, beta-(isoxazoline-5-on-2-yl)-alanine (BIA) and its higher homologue alpha-amino-gamma-(isoxazoline-5-on-2-yl)-alanine (ACI) were tested for excitotoxic potential. BIA (0.5-2.0 mM) but not ACI (2.0 mM) produced a concentration-dependent neurodegeneration in mouse cortical explants. The neuronal damage was prevented by the prior and simultaneous application of 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), indicating that it was mediated by non-N-methyl-D-aspartate type receptors. BIA (0.5-2.0 mM) activated CNQX-sensitive currents which were significantly smaller than those activated by 3-N-oxalyl-L-2,3-diaminopropanoic acid (beta-ODAP) or alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) in the majority of neurons. In a small number of cells, BIA (2 mM) produced currents which were similar in amplitude to those activated by beta-ODAP (50 microM). These results suggest that Lathyrus sativus plants engineered to block the synthesis of beta-ODAP may accumulate a neurotoxic precursor and therefore must be tested for the presence of both BIA and beta-ODAP.

The Julia Creek dunnart (Sminthopsis douglasi) was not recognized as a distinct species until 1979. The description was based on three specimens held in museum collections and, prior to 1991, it was thought that the species might have become extinct. A few small populations are now known to exist but the species is currently listed as endangered. Here we characterize seven dinucleotide microsatellite loci with between two and nine alleles per locus and expected heterozygosities ranging from 0.53 to 0.91. These markers provide an additional approach to the study of the ecology and conservation status of the Julia Creek dunnart.

Epidemics of neurotoxic disease in developing regions of the world are often associated with dietary dependence on plant components with inherent toxic potential or which have spoiled and become contaminated with mycotoxins. Diseases triggered by plant toxins include lathyrism and cassavism, types of irreversible spastic parapareses associated with staple diets of grass pea and bitter cassava root, respectively. Mildewed sugarcane poisoning, an encephalopathy and tardive dystonia, illustrates the neurotoxic effects of a widely distributed plant and fungal toxin. Food and medicinal use of the neurotoxic cycad plant is thought to have a role in the etiology of western Pacific amyotrophic lateral sclerosis and parkinsonism-dementia. Plant-associated neurotoxicity is a significant and preventable cause of morbidity in certain regions of Africa, Asia, and Oceania. © 1993 Academic Press, Inc.

We present the first set of microsatellite markers developed exclusively for an extinct taxon. Microsatellite data have been analysed in thousands of genetic studies on extant species but the technology can be problematic when applied to low copy number (LCN) DNA. It is therefore rarely used on substrates more than a few decades old. Now, with the primers and protocols presented here, microsatellite markers are available to study the extinct New Zealand moa (Aves: Dinornithiformes) and, as with single nucleotide polymorphism (SNP) technology, the markers represent a means by which the field of ancient DNA can (preservation allowing) move on from its reliance on mitochondrial DNA. Candidate markers were identified using high throughput sequencing technology (GS-FLX) on DNA extracted from fossil moa bone and eggshell. From the 'shotgun' reads, >60 primer pairs were designed and tested on DNA from bones of the South Island giant moa (Dinornis robustus). Six polymorphic loci were characterised and used to assess measures of genetic diversity. Because of low template numbers, typical of ancient DNA, allelic dropout was observed in 36-70% of the PCR reactions at each microsatellite marker. However, a comprehensive survey of allelic dropout, combined with supporting quantitative PCR data, allowed us to establish a set of criteria that maximised data fidelity. Finally, we demonstrated the viability of the primers and the protocols, by compiling a full Dinornis microsatellite dataset representing fossils of c. 600-5000 years of age. A multi-locus genotype was obtained from 74 individuals (84% success rate), and the data showed no signs of being compromised by allelic dropout. The methodology presented here provides a framework by which to generate and evaluate microsatellite data from samples of much greater antiquity than attempted before, and opens new opportunities for ancient DNA research.

β-N-Methylamino- l -alanine , a component of the neurotoxic Cycas circinalis plant, activates an ionic current which is antagonized by extracellular Ca 2+ but not by the excitatory amino acid receptor antagonists d,l -2-amino-5-phosphonovalerate (10–100 μM) or 6-cyano-7-nitroquinoxaline-2,3-dione (1–10 μM). This current was reduced by 50% in 0.5 mM extracellular Ca 2+ and 92% in 3.0 mM Ca 2+ when compared to those recorded in 0.1 mM Ca 2+ . Addition of 10 or 20 mM NaHCO 3 to β-N-methylamino- l -alanine (500 μM) potentiated the currents 224% and 578%, respectively. Addition of NaHCO 3 to the extracellular Ringers (pH 7.2) shifted the pH to 7.7 (10 mM) or 8.3 (20 mM). β-N-Methylamino- l -alanine was potentiated by NaHCO 3 at pH 7.2, 7.7 and 8.3, but the potentiation with NaHCO 3 (20 mM) was larger at pH 8.3 (5.7-fold) compared to pH 7.2 (3-fold). NaHCO 3 (20 mM) had no effect on quisqualate-, N-methyl- d -aspartate - or kainate-activated ionic currents. The β-N-methylamino- l -alanine-NaHCO 3 -activated currents were reduced 49% by 1 μM and 80% by 10 μM 6-cyano-7-nitroquinoxaline-2,3-dione suggesting an agonist action at non-N-methyl- d -aspartate-type receptors. Activity at N-methyl- d -aspartate receptors is unlikely since the gb-N-methylamino- l -alanine-NaHCO 3 currents are not antagonized by d,l -2-amino-5-phosphonovalerate (10–100 μM), potentiated by addition of glycine (10 μM) or blocked by extracellular Mg 2+ . These data are consistent with the hypothesis that interaction between β-N-methylamino- l -alanine and bicarbonate produced a new agonist species, which activates quisqualate/kainate-type glutamate receptors and may be responsible for the neurotoxicity of β-N-methylamino- l -alanine in NaHCO 3 solutions. A similar mechanism could describe how normally innocuous amino acids could acquire neurotoxic potential vivo .

The effect of acrylamide treatment on the immunocytochemical localization of microtubule-associated proteins (MAP1 and MAP2) was studied in different brain regions (cerebellum, cerebral cortex, and hippocampus) of adult rats. Animals were treated with acrylamide (estimated mean dose: 15 mg/kg/d) orally for 2 wk when they showed slight hindlimb weakness. Immunoreactivity for MAP1 and MAP2 was detected in tissue sections with monoclonal antibodies according to the Sternberger’s peroxidase-antiperoxidase technique. Intense MAP1 immunoreactivity was observed in neuronal perikarya and dendrites, with faint staining in axons. By contrast, MAP2 immunostaining was selectively observed in dendrites and neuronal perikarya. Treatment of animals with acrylamide reduced immunoreactivity for both MAP1 and MAP2 in hippocampus and cerebellum, with relatively little change in cerebral cortex. Loss of MAPs immunoreactivity in affected brain areas likely proceeded from dendrite to perikaryon. The results of this study indicate that hippocampal compromise is part of the neurotoxic picture associated with rodent exposure to acrylamide.