1
|
Zakharova MN, Bakulin IS, Abramova AA. Toxic Damage to Motor Neurons. NEUROCHEM J+ 2021. [DOI: 10.1134/s1819712421040164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Abstract—Amyotrophic lateral sclerosis (ALS) is a multifactor disease in the development of which both genetic and environmental factors play a role. Specifically, the effects of organic and inorganic toxic substances can result in an increased risk of ALS development and the acceleration of disease progression. It was described that some toxins can induce potentially curable ALS-like syndromes. In this case, the specific treatment for the prevention of the effects of the toxic factor may result in positive clinical dynamics. In this article, we review the main types of toxins that can damage motor neurons in the brain and spinal cord leading to the development of the clinical manifestation of ALS, briefly present historical data on studies on the role of toxic substances, and describe the main mechanisms of the pathogenesis of motor neuron disease associated with their action.
Collapse
|
2
|
Baguma M, Nzabara F, Maheshe Balemba G, Malembaka EB, Migabo C, Mudumbi G, Bito V, Cliff J, Rigo JM, Chabwine JN. Konzo risk factors, determinants and etiopathogenesis: What is new? A systematic review. Neurotoxicology 2021; 85:54-67. [PMID: 33964344 DOI: 10.1016/j.neuro.2021.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 05/01/2021] [Accepted: 05/03/2021] [Indexed: 12/13/2022]
Abstract
Konzo is a toxico-nutritional upper motor neuron disease causing a spastic paraparesis in schoolchildren and childbearing women in some African countries. Almost a century since the first description of konzo, its underlying etiopathogenic mechanisms and causative agent remain unknown. This paper aims at refreshing the current knowledge of konzo determinants and pathogenesis in order to enlighten potential new research and management perspectives. Literature research was performed in PubMed and Web of Science databases according to the PRISMA methodology. Available data show that cassava-derived cyanide poisoning and protein malnutrition constitute two well-documented risk factors of konzo. However, observational studies have failed to demonstrate the causal relationship between konzo and cyanide poisoning. Thiocyanate, the current marker of choice of cyanide exposure, may underestimate the actual level of cyanide poisoning in konzo patients as a larger amount of cyanide is detoxified via other unusual pathways in the context of protein malnutrition characterizing these patients. Furthermore, the appearance of konzo may be the consequence of the interplay of several factors including cyanide metabolites, nutritional deficiencies, psycho-emotional and geo-environmental factors, resulting in pathophysiologic phenomena such as excitotoxicity or oxidative stress, responsible for neuronal damage that takes place at sparse cellular and/or subcellular levels.
Collapse
Affiliation(s)
- Marius Baguma
- Department of Internal Medicine, Hôpital Provincial Général de Référence de Bukavu (HPGRB), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo; Biomedical Research Institute (BIOMED), UHasselt - Hasselt University, Agoralaan, 3590 Diepenbeek, Belgium.
| | - Fabrice Nzabara
- Department of Internal Medicine, Hôpital Provincial Général de Référence de Bukavu (HPGRB), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo; École Régionale de Santé Publique (ERSP), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo
| | - Ghislain Maheshe Balemba
- Department of Internal Medicine, Hôpital Provincial Général de Référence de Bukavu (HPGRB), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo
| | - Espoir Bwenge Malembaka
- École Régionale de Santé Publique (ERSP), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo
| | - Christiane Migabo
- Faculty of Agronomy, Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo; Department of Geography and Environmental Studies, College of Social Sciences and Humanities, Jimma University, Jimma, Ethiopia
| | - Germain Mudumbi
- Department of Pediatrics, Hôpital Provincial Général de Référence de Bukavu (HPGRB), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo
| | - Virginie Bito
- Biomedical Research Institute (BIOMED), UHasselt - Hasselt University, Agoralaan, 3590 Diepenbeek, Belgium
| | - Julie Cliff
- Faculty of Medicine, Department of Community Health, Eduardo Mondlane University, Maputo, Mozambique
| | - Jean-Michel Rigo
- Biomedical Research Institute (BIOMED), UHasselt - Hasselt University, Agoralaan, 3590 Diepenbeek, Belgium
| | - Joëlle Nsimire Chabwine
- Department of Internal Medicine, Hôpital Provincial Général de Référence de Bukavu (HPGRB), Université Catholique de Bukavu (UCB), Bukavu, Democratic Republic of the Congo; Department of Neuroscience and Movement Science, Faculty of Science and Medicine, University of Fribourg, Fribourg, Switzerland
| |
Collapse
|
3
|
Feinstein A, Choonara I. Arms sales and child health. BMJ Paediatr Open 2020; 4:e000809. [PMID: 32954017 PMCID: PMC7482471 DOI: 10.1136/bmjpo-2020-000809] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/19/2020] [Accepted: 08/20/2020] [Indexed: 01/11/2023] Open
Abstract
The adverse effects of armed conflict on child health are well recognised. The relationships among the arms trade, armed conflict and child health are less clearly defined. The arms trade is one of the largest industries in the world (total expenditure US$1917 billion in 2019), generating colossal profits to private companies and individuals at the expense of taxpayers throughout the world. The money wasted on weapons designed to kill and maim should be used for more socially useful products, such as clean water, food, health and education. The sustainable development goals can be funded by diverting money from the arms companies. Health professionals and their organisations have a responsibility to children to try and curb the ever-expanding arms industry.
Collapse
Affiliation(s)
- Andrew Feinstein
- Shadow World Investigations (formerly Corruption Watch UK), London, UK
| | - Imti Choonara
- Child Health, University of Nottingham School of Medicine, Derby, UK
| |
Collapse
|
4
|
Kadir A, Shenoda S, Goldhagen J. Effects of armed conflict on child health and development: A systematic review. PLoS One 2019; 14:e0210071. [PMID: 30650095 PMCID: PMC6334973 DOI: 10.1371/journal.pone.0210071] [Citation(s) in RCA: 75] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Accepted: 12/17/2018] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Armed conflicts affect more than one in 10 children globally. While there is a large literature on mental health, the effects of armed conflict on children's physical health and development are not well understood. This systematic review summarizes the current and past knowledge on the effects of armed conflict on child health and development. METHODS A systematic review was performed with searches in major and regional databases for papers published 1 January 1945 to 25 April 2017. Included studies provided data on physical and/or developmental outcomes associated with armed conflict in children under 18 years. Data were extracted on health outcomes, displacement, social isolation, experience of violence, orphan status, and access to basic needs. The review is registered with PROSPERO: CRD42017036425. FINDINGS Among 17,679 publications screened, 155 were eligible for inclusion. Nearly half of the 131 quantitative studies were case reports, chart or registry reviews, and one-third were cross-sectional studies. Additionally, 18 qualitative and 6 mixed-methods studies were included. The papers describe mortality, injuries, illnesses, environmental exposures, limitations in access to health care and education, and the experience of violence, including torture and sexual violence. Studies also described conflict-related social changes affecting child health. The geographical coverage of the literature is limited. Data on the effects of conflict on child development are scarce. INTERPRETATION The available data document the pervasive effect of conflict as a form of violence against children and a negative social determinant of child health. There is an urgent need for research on the mechanisms by which conflict affects child health and development and the relationship between physical health, mental health, and social conditions. Particular priority should be given to studies on child development, the long term effects of exposure to conflict, and protective and mitigating factors against the harmful effects of armed conflict on children.
Collapse
Affiliation(s)
- Ayesha Kadir
- Malmö Institute for Studies of Migration, Diversity and Welfare, Malmö University, Malmö, Sweden
- Médecins Sans Frontières, Geneva, Switzerland
| | - Sherry Shenoda
- Division of Community and Societal Pediatrics, University of Florida College of Medicine—Jacksonville, Jacksonville, Florida, United States of America
| | - Jeffrey Goldhagen
- Division of Community and Societal Pediatrics, University of Florida College of Medicine—Jacksonville, Jacksonville, Florida, United States of America
| |
Collapse
|
5
|
Tamele IJ, Silva M, Vasconcelos V. The Incidence of Tetrodotoxin and Its Analogs in the Indian Ocean and the Red Sea. Mar Drugs 2019; 17:E28. [PMID: 30621279 PMCID: PMC6357042 DOI: 10.3390/md17010028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2018] [Revised: 12/28/2018] [Accepted: 12/29/2018] [Indexed: 11/24/2022] Open
Abstract
Tetrodotoxin (TTX) is a potent marine neurotoxin with bacterial origin. To date, around 28 analogs of TTX are known, but only 12 were detected in marine organisms, namely TTX, 11-oxoTTX, 11-deoxyTTX, 11-norTTX-6(R)-ol, 11-norTTX-6(S)-ol, 4-epiTTX, 4,9-anhydroTTX, 5,6,11-trideoxyTTX, 4-CysTTX, 5-deoxyTTX, 5,11-dideoxyTTX, and 6,11-dideoxyTTX. TTX and its derivatives are involved in many cases of seafood poisoning in many parts of the world due to their occurrence in different marine species of human consumption such as fish, gastropods, and bivalves. Currently, this neurotoxin group is not monitored in many parts of the world including in the Indian Ocean area, even with reported outbreaks of seafood poisoning involving puffer fish, which is one of the principal TTX vectors know since Egyptian times. Thus, the main objective of this review was to assess the incidence of TTXs in seafood and associated seafood poisonings in the Indian Ocean and the Red Sea. Most reported data in this geographical area are associated with seafood poisoning caused by different species of puffer fish through the recognition of TTX poisoning symptoms and not by TTX detection techniques. This scenario shows the need of data regarding TTX prevalence, geographical distribution, and its vectors in this area to better assess human health risk and build effective monitoring programs to protect the health of consumers in Indian Ocean area.
Collapse
Affiliation(s)
- Isidro José Tamele
- CIIMAR/CIMAR-Interdisciplinary Center of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto, Avenida General Norton de Matos, 4450-238 Matosinhos, Portugal.
- Institute of Biomedical Science Abel Salazar, University of Porto, R. Jorge de Viterbo Ferreira 228, 4050-313 Porto, Portugal.
- Faculty of Sciences, Eduardo Mondlane University, Av. Julius Nyerere, nr 3453, Campus Principal, 257 Maputo, Mozambique.
| | - Marisa Silva
- CIIMAR/CIMAR-Interdisciplinary Center of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto, Avenida General Norton de Matos, 4450-238 Matosinhos, Portugal.
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4619-007 Porto, Portugal.
| | - Vitor Vasconcelos
- CIIMAR/CIMAR-Interdisciplinary Center of Marine and Environmental Research, University of Porto, Terminal de Cruzeiros do Porto, Avenida General Norton de Matos, 4450-238 Matosinhos, Portugal.
- Department of Biology, Faculty of Sciences, University of Porto, Rua do Campo Alegre, 4619-007 Porto, Portugal.
| |
Collapse
|
6
|
Boivin MJ, Okitundu D, Makila-Mabe B, Sombo MT, Mumba D, Sikorskii A, Mayambu B, Tshala-Katumbay D. Cognitive and motor performance in Congolese children with konzo during 4 years of follow-up: a longitudinal analysis. Lancet Glob Health 2017; 5:e936-e947. [PMID: 28807191 PMCID: PMC5594926 DOI: 10.1016/s2214-109x(17)30267-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Revised: 06/13/2017] [Accepted: 06/26/2017] [Indexed: 11/23/2022]
Abstract
BACKGROUND Konzo is an irreversible upper-motor neuron disorder affecting children dependent on bitter cassava for food. The neurocognitive ability of children with konzo over time has yet to be fully documented. METHODS We did a longitudinal study in a konzo outbreak zone continuously affected by konzo since 1990, in the district of Kahemba, southern Bandundu Province, Congo. We enrolled children with a record of neurological diagnosis of konzo in Kahemba town. For all study children with konzo enrolled in the final sample for the baseline assessment, a neurological exam was done by neurologists to confirm konzo diagnosis using the 1996 WHO criteria at 2 years and 4 years. In the initial baseline sample for each child with konzo, we attempted to get consent from a comparison child without konzo (1996 WHO criteria) within 2 years of age, from a neighbouring household who met inclusion criteria. The neuropsychological assessments were the Kaufman Assessment Battery for Children, second edition (KABC-II), and the Bruininks-Oseretsky Test of Motor Proficiency, second edition (BOT-2). FINDINGS Data collection occurred between Oct 12, 2011, and Aug 14, 2015, in the town of Kahemba. 123 children from the Congo with konzo and 87 presumably healthy children without konzo from neighbouring households were enrolled. The planned assessments were completed by 76 children with konzo and 82 children without konzo at 2-year follow-up, and by 55 children with konzo and 33 children without konzo at 4-year follow-up. Boys with konzo did worse than those without konzo on the KABC-II Learning (p=0·0424) and on the Mental Processing Index (MPI; p=0·0111) assessments at 2-year follow-up, but girls did not. These differences observed in boys might have been caused by stunting. At 4-year follow-up, the difference in KABC-II MPI score between boys or girls with or without konzo was not significant. Both boys and girls with konzo had lower scores on BOT-2 than children without konzo at both follow-up times (p<0·0001). These differences were not attenuated when controlling for physical growth. Boys with and without konzo declined on BOT-2 fine motor proficiency at 2-year follow-up (boys with konzo p=0·0076; boys without konzo p=0·0224) and KABC-II MPI performance at 2-year follow-up and 4-year follow-up (2 years: boys with konzo p<0·0001, boys without konzo p=0·0213; 4 years: boys with konzo p=0·0256, boys without konzo p=0·10), but that was not the case for the girls with scores remaining stable regardless of konzo status. For boys, increases in urinary thiocyanate concentration was significantly associated with reductions in BOT-2 motor proficiency (p=0·0321), but was not significantly associated in girls and urinary thiocyanate concentration was not associated with KABC-II MPI score for either boys or girls. INTERPRETATION Motor and cognitive performance continues to be significantly impaired in boys with konzo at 2-year follow-up compared with boys without konzo. Because these impairments are associated in part with exposure to poorly processed cassava as measured by urinary thiocyanate, interventions are urgently needed to ensure improved processing of cassava to detoxify this food source. FUNDING US National Institutes of Health.
Collapse
Affiliation(s)
- Michael J Boivin
- Department of Psychiatry and Neurology & Ophthalmology, Michigan State University, East Lansing, MI, USA.
| | - Daniel Okitundu
- Centre NeuroPsychopathologique (CNPP), University of Kinshasa, Kinshasa, Congo
| | - Bumoko Makila-Mabe
- Centre NeuroPsychopathologique (CNPP), University of Kinshasa, Kinshasa, Congo
| | - Marie-Therese Sombo
- Centre NeuroPsychopathologique (CNPP), University of Kinshasa, Kinshasa, Congo
| | - Dieudonne Mumba
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Congo; National Institute for Biomedical Research (INRB), Kinshasa, Congo
| | - Alla Sikorskii
- Department of Psychiatry and Department of Statistics and Probability, Michigan State University, East Lansing, MI, USA
| | - Banea Mayambu
- Ministry of Health National Program on Nutrition (PRONANUT), Kinshasa, Congo
| | - Desire Tshala-Katumbay
- Centre NeuroPsychopathologique (CNPP), University of Kinshasa, Kinshasa, Congo; National Institute for Biomedical Research (INRB), Kinshasa, Congo; Department of Neurology and School of Public Health, Oregon Health & Science University, Portland, OR, USA
| |
Collapse
|
7
|
Pattern and Epidemiology of Poisoning in the East African Region: A Literature Review. J Toxicol 2016; 2016:8789624. [PMID: 27882048 PMCID: PMC5108859 DOI: 10.1155/2016/8789624] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2016] [Accepted: 09/19/2016] [Indexed: 11/19/2022] Open
Abstract
The establishment and strengthening of poisons centres was identified as a regional priority at the first African regional meeting on the Strategic Approach to International Chemicals Management (SAICM) in June 2006. At this meeting, the possibility of a subregional poisons centre, that is, a centre in one country serving multiple countries, was suggested. The WHO Headquarters following consultation with counterparts at the WHO Regional Office for Africa (AFRO) and the SAICM Africa Regional Focal Point successfully submitted a proposal to the SAICM Quick Start Programme (QSP) Trust Fund Committee for a feasibility study into a subregional poisons centre in the Eastern Africa subregion. However, before such a study could be conducted it was deemed necessary to carry out a literature review on the patterns and epidemiology of poisoning in this region so as to inform the feasibility study. The current paper presents the results of this literature review. The literature search was done in the months of June and July 2012 by two independent reviewers with no language or publication date restrictions using defined search terms on PUBMED. After screening, the eventual selection of articles for review and inclusion in this study was done by a third reviewer.
Collapse
|
8
|
Gleadow R, Pegg A, Blomstedt CK. Resilience of cassava (Manihot esculenta Crantz) to salinity: implications for food security in low-lying regions. JOURNAL OF EXPERIMENTAL BOTANY 2016; 67:5403-5413. [PMID: 27506218 PMCID: PMC5049390 DOI: 10.1093/jxb/erw302] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Rising sea levels are threatening agricultural production in coastal regions due to inundation and contamination of groundwater. The development of more salt-tolerant crops is essential. Cassava is an important staple, particularly among poor subsistence farmers. Its tolerance to drought and elevated temperatures make it highly suitable for meeting global food demands in the face of climate change, but its ability to tolerate salt is unknown. Cassava stores nitrogen in the form of cyanogenic glucosides and can cause cyanide poisoning unless correctly processed. Previous research demonstrated that cyanide levels are higher in droughted plants, possibly as a mechanism for increasing resilience to oxidative stress. We determined the tolerance of cassava to salt at two different stages of development, and tested the hypothesis that cyanide toxicity would be higher in salt-stressed plants. Cassava was grown at a range of concentrations of sodium chloride (NaCl) at two growth stages: tuber initiation and tuber expansion. Established plants were able to tolerate 100mM NaCl but in younger plants 40mM was sufficient to retard plant growth severely. Nutrient analysis showed that plants were only able to exclude sodium at low concentrations. The foliar cyanogenic glucoside concentration in young plants increased under moderate salinity stress but was lower in plants grown at high salt. Importantly, there was no significant change in the cyanogenic glucoside concentration in the tubers. We propose that the mechanisms for salinity tolerance are age dependent, and that this can be traced to the relative cost of leaves in young and old plants.
Collapse
Affiliation(s)
- Ros Gleadow
- School of Biological Sciences, Monash University, Clayton, Melbourne, Victoria 3800, Australia
| | - Amelia Pegg
- School of Biological Sciences, Monash University, Clayton, Melbourne, Victoria 3800, Australia
| | - Cecilia K Blomstedt
- School of Biological Sciences, Monash University, Clayton, Melbourne, Victoria 3800, Australia
| |
Collapse
|
9
|
Pinto-Zevallos DM, Pareja M, Ambrogi BG. Current knowledge and future research perspectives on cassava (Manihot esculenta Crantz) chemical defenses: An agroecological view. PHYTOCHEMISTRY 2016; 130:10-21. [PMID: 27316676 DOI: 10.1016/j.phytochem.2016.05.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Revised: 05/25/2016] [Accepted: 05/31/2016] [Indexed: 05/10/2023]
Abstract
Cassava (Manihot esculenta Crantz) is one of the most important staple crops worldwide. It constitutes the major source of carbohydrates for millions of low-income people living in rural areas, as well as a cash crop for smallholders in tropical and sub-tropical regions. The Food and Agriculture Organization of the United Nations predicts that cassava plantations will increase and production systems will intensify in the future, highlighting the need for developing strategies that improve the sustainability of production. Plant chemical defenses hold the potential for developing pest management strategies, as these plant traits can influence the behavior and performance of both pests and beneficial arthropods. Cassava plants are well-defended and produce a number of compounds involved in direct defense, such as cyanogenic glycosides, flavonoid glycosides, and hydroxycoumarins. In addition, volatile organic compounds induced upon herbivory and the secretion of extrafloral nectar act as indirect defense against herbivores by recruiting natural enemies. Here, cassava chemical defenses against pest arthropods are reviewed, with the aim of identifying gaps in our knowledge and areas of research that deserve further investigation for developing sound pest control strategies to improve sustainable production of this crop, and how these defenses can be used to benefit other crops. Cyanogenic content in cassava is also highly toxic to humans, and can cause irreversible health problems even at sub-lethal doses when consumed over prolonged periods. Therefore, the promotion of chemical defense in this crop should not aggravate these problems, and must be accompanied with the education on processing methods that reduce human exposure to cyanide.
Collapse
Affiliation(s)
- Delia M Pinto-Zevallos
- Laboratório de Ecologia Química, Departamento de Ecologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe - UFS, Av. Marechal Rondon, s/n - Jardim Rosa Elze, CEP 49100-000, São Cristóvão, SE, Brazil.
| | - Martín Pareja
- Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas - UNICAMP, Caixa Postal 6109, Rua Monteiro Lobato 255, CEP 13083-862, Campinas, SP, Brazil
| | - Bianca G Ambrogi
- Laboratório de Ecologia Química, Departamento de Ecologia, Centro de Ciências Biológicas e da Saúde, Universidade Federal de Sergipe - UFS, Av. Marechal Rondon, s/n - Jardim Rosa Elze, CEP 49100-000, São Cristóvão, SE, Brazil
| |
Collapse
|
10
|
Tshala-Katumbay DD, Ngombe NN, Okitundu D, David L, Westaway SK, Boivin MJ, Mumba ND, Banea JP. Cyanide and the human brain: perspectives from a model of food (cassava) poisoning. Ann N Y Acad Sci 2016; 1378:50-57. [PMID: 27450775 DOI: 10.1111/nyas.13159] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 05/29/2016] [Accepted: 06/01/2016] [Indexed: 11/26/2022]
Abstract
Threats by fundamentalist leaders to use chemical weapons have resulted in renewed interest in cyanide toxicity. Relevant insights may be gained from studies on cyanide mass intoxication in populations relying on cyanogenic cassava as the main source of food. In these populations, sublethal concentrations (up to 80 μmol/l) of cyanide in the blood are commonplace and lead to signs of acute toxicity. Long-term toxicity signs include a distinct and irreversible spastic paralysis, known as konzo, and cognition deficits, mainly in sequential processing (visual-spatial analysis) domains. Toxic culprits include cyanide (mitochondrial toxicant), thiocyanate (AMPA-receptor chaotropic cyanide metabolite), cyanate (protein-carbamoylating cyanide metabolite), and 2-iminothiazolidine-4-carboxylic acid (seizure inducer). Factors of susceptibility include younger age, female gender, protein-deficient diet, and, possibly, the gut functional metagenome. The existence of uniquely exposed and neurologically affected populations offers invaluable research opportunities to develop a comprehensive understanding of cyanide toxicity and test or validate point-of-care diagnostic tools and treatment options to be included in preparedness kits in response to cyanide-related threats.
Collapse
Affiliation(s)
- Desire D Tshala-Katumbay
- Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, Oregon. .,Department of Neurology, University of Kinshasa, Kinshasa, Congo. .,National Nutrition Program, Ministry of Health, and Kinshasa School of Public Health, Kinshasa, Congo.
| | | | - Daniel Okitundu
- Department of Neurology, University of Kinshasa, Kinshasa, Congo
| | - Larry David
- Department of Biochemistry and Proteomic Share Resource, Oregon Health & Science University, Portland, Oregon
| | - Shawn K Westaway
- Department of Neurology, School of Medicine, Oregon Health & Science University, Portland, Oregon
| | - Michael J Boivin
- Department of Psychiatry and Neurology/Ophthalmology, Michigan State University, East Lansing, Michigan
| | - Ngoyi D Mumba
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Congo.,Institut National de Recherches Biomédicales (INRB), Kinshasa, Congo
| | - Jean-Pierre Banea
- National Nutrition Program, Ministry of Health, and Kinshasa School of Public Health, Kinshasa, Congo
| |
Collapse
|
11
|
Banea JP, Bradbury JH, Nahimana D, Denton IC, Foster MP, Mekob N, Kuwa N, Bokundabi G, Foley WJ. Health factors associated with persistent konzo in four villages in the Democratic Republic of Congo (DRC). ACTA ACUST UNITED AC 2016. [DOI: 10.5897/ajfs2015.1378] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
|
12
|
Tshala-Katumbay D, Mwanza JC, Rohlman DS, Maestre G, Oriá RB. A global perspective on the influence of environmental exposures on the nervous system. Nature 2015; 527:S187-92. [PMID: 26580326 PMCID: PMC4772865 DOI: 10.1038/nature16034] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Economic transitions in the era of globalization warrant a fresh look at the neurological risks associated with environmental change. These are driven by industrial expansion, transfer and mobility of goods, climate change and population growth. In these contexts, risk of infectious and non-infectious diseases are shared across geographical boundaries. In low- and middle-income countries, the risk of environmentally mediated brain disease is augmented several fold by lack of infrastructure, poor health and safety regulations, and limited measures for environmental protection. Neurological disorders may occur as a result of direct exposure to chemical and/or non-chemical stressors, including but not limited to, ultrafine particulate matters. Individual susceptibilities to exposure-related diseases are modified by genetic, epigenetic and metagenomic factors. The existence of several uniquely exposed populations, including those in the areas surrounding the Niger Delta or north western Amazon oil operations; those working in poorly regulated environments, such as artisanal mining industries; or those, mostly in sub-Saharan Africa, relying on cassava as a staple food, offers invaluable opportunities to advance the current understanding of brain responses to environmental challenges. Increased awareness of the brain disorders that are prevalent in low- and middle-income countries and investments in capacity for further environmental health-related research are positive steps towards improving human health.
Collapse
Affiliation(s)
- Desire Tshala-Katumbay
- Department of Neurology, Oregon Health &Science University, Portland, Oregon, 97239, USA.,National Institute of Biomedical Research, 1197 Kinshasa I, Congo.,Department of Neurology, University of Kinshasa, 825 Kinshasa XI, Congo
| | - Jean-Claude Mwanza
- Department of Ophthalmology, University of North Carolina at Chapel Hill, North Carolina 27599, USA
| | - Diane S Rohlman
- Occupational and Environmental Health, The University of Iowa, Iowa 52242, USA.,Oregon Institute of Occupational Health Sciences, Oregon Health and Science University, Portland, Oregon, 97239, USA
| | - Gladys Maestre
- G. H. Sergievsky Center, Columbia University Medical Center, New York, New York 10032, USA
| | - Reinaldo B Oriá
- Department of Morphology and Institute of Biomedicine, Faculty of Medicine, Federal University of Ceara, Fortaleza 60020, Brazil
| |
Collapse
|
13
|
Reducing neurodevelopmental disorders and disability through research and interventions. Nature 2015; 527:S155-60. [PMID: 26580321 DOI: 10.1038/nature16029] [Citation(s) in RCA: 92] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We define neurodevelopment as the dynamic inter-relationship between genetic, brain, cognitive, emotional and behavioural processes across the developmental lifespan. Significant and persistent disruption to this dynamic process through environmental and genetic risk can lead to neurodevelopmental disorders and disability. Research designed to ameliorate neurodevelopmental disorders in low- and middle-income countries, as well as globally, will benefit enormously from the ongoing advances in understanding their genetic and epigenetic causes, as modified by environment and culture. We provide examples of advances in the prevention and treatment of, and the rehabilitation of those with, neurodevelopment disorders in low- and middle-income countries, along with opportunities for further strategic research initiatives. Our examples are not the only possibilities for strategic research, but they illustrate problems that, when solved, could have a considerable impact in low-resource settings. In each instance, research in low- and middle-income countries led to innovations in identification, surveillance and treatment of a neurodevelopmental disorder. These innovations have also been integrated with genotypic mapping of neurodevelopmental disorders, forming important preventative and rehabilitative interventions with the potential for high impact. These advances will ultimately allow us to understand how epigenetic influences shape neurodevelopmental risk and resilience over time and across populations. Clearly, the most strategic areas of research opportunity involve cross-disciplinary integration at the intersection between the environment, brain or behaviour neurodevelopment, and genetic and epigenetic science. At these junctions a robust integrative cross-disciplinary scientific approach is catalysing the creation of technologies and interventions for old problems. Such approaches will enable us to achieve and sustain the United Nations moral and legal mandate for child health and full development as a basic global human right.
Collapse
|
14
|
Gibb H, Devleesschauwer B, Bolger PM, Wu F, Ezendam J, Cliff J, Zeilmaker M, Verger P, Pitt J, Baines J, Adegoke G, Afshari R, Liu Y, Bokkers B, van Loveren H, Mengelers M, Brandon E, Havelaar AH, Bellinger D. World Health Organization estimates of the global and regional disease burden of four foodborne chemical toxins, 2010: a data synthesis. F1000Res 2015; 4:1393. [PMID: 26918123 PMCID: PMC4755404 DOI: 10.12688/f1000research.7340.1] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 11/19/2015] [Indexed: 01/07/2023] Open
Abstract
Background Chemical exposures have been associated with a variety of health effects; however, little is known about the global disease burden from foodborne chemicals. Food can be a major pathway for the general population's exposure to chemicals, and for some chemicals, it accounts for almost 100% of exposure. Methods and Findings Groups of foodborne chemicals, both natural and anthropogenic, were evaluated for their ability to contribute to the burden of disease. The results of the analyses on four chemicals are presented here - cyanide in cassava, peanut allergen, aflatoxin, and dioxin. Systematic reviews of the literature were conducted to develop age- and sex-specific disease incidence and mortality estimates due to these chemicals. From these estimates, the numbers of cases, deaths and disability adjusted life years (DALYs) were calculated. For these four chemicals combined, the total number of illnesses, deaths, and DALYs in 2010 is estimated to be 339,000 (95% uncertainty interval [UI]: 186,000-1,239,000); 20,000 (95% UI: 8,000-52,000); and 1,012,000 (95% UI: 562,000-2,822,000), respectively. Both cyanide in cassava and aflatoxin are associated with diseases with high case-fatality ratios. Virtually all human exposure to these four chemicals is through the food supply. Conclusion Chemicals in the food supply, as evidenced by the results for only four chemicals, can have a significant impact on the global burden of disease. The case-fatality rates for these four chemicals range from low (e.g., peanut allergen) to extremely high (aflatoxin and liver cancer). The effects associated with these four chemicals are neurologic (cyanide in cassava), cancer (aflatoxin), allergic response (peanut allergen), endocrine (dioxin), and reproductive (dioxin).
Collapse
Affiliation(s)
- Herman Gibb
- Gibb Epidemiology Consulting LLC, Arlington, VA, USA
| | - Brecht Devleesschauwer
- Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium
- Institute of Health and Society (IRSS), Université catholique de Louvain, Brussels, Belgium
- Department of Biomedical Sciences, Institute of Tropical Medicine, Antwerp, Belgium
- Emerging Pathogens Institute and Animal Sciences Department, University of Florida, Gainesville, FL, USA
| | - P. Michael Bolger
- Exponent, Center for Chemical Regulation and Food Safety, Washington, DC, USA
| | - Felicia Wu
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, MI, USA
- Department of Agricultural, Food, and Resource Economics, Michigan State University, East Lansing, MI, USA
| | - Janine Ezendam
- National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands
| | - Julie Cliff
- Faculdade de Medicina, Universidade Eduardo Mondlane, Maputo, Mozambique
| | - Marco Zeilmaker
- National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands
| | - Philippe Verger
- Department of Food Safety and Zoonoses, World Health Organization, Geneva, Switzerland
| | - John Pitt
- CSIRO Food and Nutrition Flagship, North Ryde, Australia
| | - Janis Baines
- Food Data Analysis Section, Food Standards Australia New Zealand, Canberra, Australia
| | - Gabriel Adegoke
- Department of Food Technology, University of Ibadan, Ibadan, Nigeria
| | - Reza Afshari
- Environmental Health Services, British Columbia Centre for Disease Control, Vancouver, BC, Canada
| | - Yan Liu
- INTERTEK, Oak Brook, IL, USA
| | - Bas Bokkers
- National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands
| | - Henk van Loveren
- National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands
| | - Marcel Mengelers
- National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands
| | - Esther Brandon
- National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands
| | - Arie H. Havelaar
- National Institute for Public Health and the Environment (RIVM), Bilthoven, Netherlands
- Emerging Pathogens Institute and Animal Sciences Department, University of Florida, Gainesville, FL, USA
- Institute for Risk Assessment Sciences, Utrecht University, Utrecht, Netherlands
| | - David Bellinger
- Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| |
Collapse
|
15
|
Oluwole OSA. Cyclical konzo epidemics and climate variability. Ann Neurol 2015; 77:371-80. [PMID: 25523348 DOI: 10.1002/ana.24334] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Revised: 11/30/2014] [Accepted: 12/07/2014] [Indexed: 11/05/2022]
Abstract
Konzo epidemics have occurred during droughts in the Democratic Republic of Congo (DR Congo) for >70 years, but also in Mozambique, Tanzania, and the Central African Republic. The illness is attributed to exposure to cyanide from cassava foods, on which the population depends almost exclusively during droughts. Production of cassava, a drought-resistant crop, has been shown to correlate with cyclical changes in precipitation in konzo-affected countries. Here we review the epidemiology of konzo as well as models of its pathogenesis. A spectral analysis of precipitation and konzo is performed to determine whether konzo epidemics are cyclical and whether there is spectral coherence. Time series of environmental temperature, precipitation, and konzo show cyclical changes. Periodicities of dominant frequencies in the spectra of precipitation and konzo range from 3 to 6 years in DR Congo. There is coherence of the spectra of precipitation and konzo. The magnitude squared coherence of 0.9 indicates a strong relationship between variability of climate and konzo epidemics. Thus, it appears that low precipitation phases of climate variability reduce the yield of food crops except cassava, upon which the population depends for supply of calories during droughts. Presence of very high concentrations of thiocyanate (SCN(-) ), the major metabolite of cyanide, in the bodily fluids of konzo subjects is a consequence of dietary exposure to cyanide, which follows intake of poorly processed cassava roots. Because cyanogens and minor metabolites of cyanide have not induced konzo-like illnesses, SCN(-) remains the most likely neurotoxicant of konzo. Public health control of konzo will require food and water programs during droughts. [Correction added on 26 February 2015, after first online publication: abstract reformatted per journal style]
Collapse
|
16
|
Makila-Mabe BG, Kikandau KJ, Sombo TM, Okitundu DL, Mwanza JC, Boivin MJ, Ngoyi MD, Muyembe JJT, Banea JP, Boss GR, Tshala-Katumbay D. Serum 8,12-iso-iPF2α-VI isoprostane marker of oxidative damage and cognition deficits in children with konzo. PLoS One 2014; 9:e107191. [PMID: 25222616 PMCID: PMC4164531 DOI: 10.1371/journal.pone.0107191] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Accepted: 08/07/2014] [Indexed: 11/21/2022] Open
Abstract
We sought to determine whether motor and cognitive deficits associated with cassava (food) cyanogenic poisoning were associated with high concentrations of F2-isoprostanes, well-established indicators of oxidative damage. Concentrations of serum F2-isoprostanes were quantified by LC-MS/MS and anchored to measures of motor proficiency and cognitive performance, which were respectively assessed through BOT-2 (Bruininks/Oseretsky Test, 2nd Edition) and KABC-II (Kaufman Assessment Battery for Children, 2nd edition) testing of 40 Congolese children (21 with konzo and 19 presumably healthy controls, overall mean age (SD): 9.3 (3.2) years). Exposure to cyanide was ascertained by concentrations of its main metabolite thiocyanate (SCN) in plasma and urine. Overall, SCN concentrations ranged from 91 to 325 and 172 to 1032 µmol/l in plasma and urine, respectively. Serum isoprostanes ranged from 0.1 to 0.8 (Isoprostane-III), 0.8 to 8.3 (total Isoprostane-III), 0.1 to 1.5 (Isoprostane-VI), 2.0 to 9.0 (total Isoprostane-VI), or 0.2 to 1.3 ng/ml (8,12-iso-iPF2α-VI isoprostane). Children with konzo poorly performed at the BOT-2 and KABC-II testing relative to presumably healthy children (p<0.01). Within regression models adjusting for age, gender, motor proficiency, and other biochemical variables, 8,12-iso-iPF2α-VI isoprostane was significantly associated with the overall cognitive performance (β = −32.36 (95% CI: −51.59 to −13.03; P<0.001). This model explained over 85% of variation of the KABC-II score in children with konzo, but was not significant in explaining the motor proficiency impairment. These findings suggest that cognitive deficits and, possibly, brain injury associated with cassava poisoning is mediated in part by oxidative damage in children with konzo. 8,12-iso-iPF2α-VI isoprostane appears to be a good marker of the neuropathogenic mechanisms of konzo and may be used to monitor the impact of interventional trials to prevent the neurotoxic effects of cassava cyanogenic poisoning.
Collapse
Affiliation(s)
| | - Kambale J. Kikandau
- Department of Biomedical Sciences, University of Kinshasa, Kinshasa, Congo-Kinshasa
| | - Thérèse M. Sombo
- Department of Neurology, University of Kinshasa, Kinshasa, Congo-Kinshasa
| | - Daniel L. Okitundu
- Department of Neurology, University of Kinshasa, Kinshasa, Congo-Kinshasa
| | - Jean-Claude Mwanza
- Department of Ophthalmology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America
| | - Michael J. Boivin
- Department of Psychiatry and Neurology/Ophthalmology, Michigan State University, East Lansing, Michigan, United States of America
| | - Mumba D. Ngoyi
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Congo-Kinshasa
- Department of Parasitology, Institut National de Recherches Biomédicales, Kinshasa, Congo-Kinshasa
| | - Jean-Jacques T. Muyembe
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Congo-Kinshasa
- Department of Parasitology, Institut National de Recherches Biomédicales, Kinshasa, Congo-Kinshasa
| | - Jean-Pierre Banea
- Department of Nutrition, School of Public Health & National Nutrition Program, Ministry of Health, Kinshasa, Congo-Kinshasa
| | - Gerard R. Boss
- Department of Medicine, University of California San Diego, La Jolla, California, United States of America
| | - Desiré Tshala-Katumbay
- Department of Neurology, University of Kinshasa, Kinshasa, Congo-Kinshasa
- Department of Neurology, Oregon Health & Science University, Portland, Oregon, United States of America
- Oregon Institute of Occupational Health Sciences, Oregon Health & Science University, Portland, Oregon, United States of America
- * E-mail:
| |
Collapse
|
17
|
Bradbury JH, Denton IC. Mild method for removal of cyanogens from cassava leaves with retention of vitamins and protein. Food Chem 2014; 158:417-20. [DOI: 10.1016/j.foodchem.2014.02.132] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 08/30/2013] [Accepted: 02/23/2014] [Indexed: 10/25/2022]
|
18
|
Boivin MJ, Okitundu D, Makila-Mabe Bumoko G, Sombo MT, Mumba D, Tylleskar T, Page CF, Tamfum Muyembe JJ, Tshala-Katumbay D. Neuropsychological effects of konzo: a neuromotor disease associated with poorly processed cassava. Pediatrics 2013; 131:e1231-9. [PMID: 23530166 PMCID: PMC3608487 DOI: 10.1542/peds.2012-3011] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Konzo is an irreversible upper-motor neuron disorder affecting children dependent on bitter cassava for food. Although the neuroepidemiology of konzo is well characterized, we report the first neuropsychological findings. METHOD Children with konzo in the Democratic Republic of Congo (mean age 8.7 years) were compared with children without konzo (mean age 9.1 years) on the Kaufman Assessment Battery for Children, second edition (KABC-II), and the Bruininks-Oseretsky Test of Motor Proficiency, second edition (BOT-2). Both groups were also compared with normative KABC measures from earlier studies in a nearby nonkonzo region. RESULTS Using a Kruskal-Wallis test, children with konzo did worse on the KABC-II simultaneous processing (visual-spatial analysis) (K [1] = 8.78, P = .003) and mental processing index (MPI) (K [1] = 4.56, P = .03) than children without konzo. Both konzo and nonkonzo groups had poorer KABC sequential processing (memory) and MPI relative to the normative group from a nonkonzo region (K [2] = 75.55, P < .001). Children with konzo were lower on BOT-2 total (K [1] = 83.26, P < .001). KABC-II MPI and BOT-2 total were predictive of konzo status in a binary logistic regression model: odds ratio = 1.41, P < .013; 95% confidence interval 1.13-1.69. CONCLUSIONS Motor proficiency is dramatically affected, and both children with and without konzo have impaired neurocognition compared with control children from a nonoutbreak area. This may evidence a subclinical neurocognitive form of the disease, extending the human burden of konzo with dramatic public health implications.
Collapse
Affiliation(s)
| | | | | | | | - Dieudonne Mumba
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo;,Institut National de Recherches Biomédicales, Kinshasa, Democratic Republic of Congo
| | - Thorkild Tylleskar
- Center for International Health, University of Bergen, Bergen, Norway; and
| | - Connie F. Page
- Department of Statistics and Probability, Michigan State University, East Lansing, Michigan
| | - Jean-Jacques Tamfum Muyembe
- Department of Tropical Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo;,Institut National de Recherches Biomédicales, Kinshasa, Democratic Republic of Congo
| | - Desire Tshala-Katumbay
- Department of Neurology, and,Department of Neurology and Center for Research on Occupational and Environmental Toxicology, Oregon Health and Science University, Portland, Oregon
| |
Collapse
|
19
|
Assessing diet in populations at risk for konzo and neurolathyrism. Food Chem Toxicol 2011; 49:655-61. [DOI: 10.1016/j.fct.2010.08.006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 06/29/2010] [Accepted: 08/05/2010] [Indexed: 11/20/2022]
|
20
|
Adamolekun B. Neurological disorders associated with cassava diet: a review of putative etiological mechanisms. Metab Brain Dis 2011; 26:79-85. [PMID: 21327546 DOI: 10.1007/s11011-011-9237-y] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Accepted: 02/02/2011] [Indexed: 10/18/2022]
Abstract
Tropical ataxic neuropathy (TAN) and epidemic spastic paraparesis (konzo) are two neurological disorders associated with the consumption of cassava (Manihot esculenta) in several African countries. TAN is characterized by sensory polyneuropathy, sensory ataxia, bilateral optic atrophy and bilateral sensori-neural deafness. It occurs in elderly individuals subsisting on a monotonous cassava diet with minimal protein supplementation. Konzo is a syndrome of symmetrical spastic paraparesis with a predilection for children and young women and invariably associated with consumption of inadequately processed bitter cassava roots with minimal protein supplementation. Despite numerous epidemiological, clinical and biochemical studies aimed at elucidating the etiological mechanisms of these disorders, their etiologies remain unknown, and there is no known treatment. The diseases continue to be prevalent in endemic areas, causing significant disability and increased mortality. A fresh appraisal of the putative etiologic mechanisms proposed for these intriguing and enigmatic syndromes is presented in this paper. Evidences against a causal role for cyanide intoxication are discussed, and evidences implicating thiamine deficiency as a unifying etiological mechanism for these neurological syndromes are presented. It is concluded that urgent research is needed to evaluate thiamine status and implement a therapeutic trial of thiamine in these debilitating neurological disorders.
Collapse
Affiliation(s)
- Bola Adamolekun
- Department of Neurology, University of Tennessee Health Science Center, 855 Monroe Avenue, Memphis, TN 38163, USA.
| |
Collapse
|
21
|
Muoki PN, Maziya-Dixon B. Household Utilization of Manioc (Manihot EsculentaCrantz) in Northern Mozambique. Ecol Food Nutr 2010; 49:337-56. [DOI: 10.1080/03670244.2010.507435] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
22
|
Affiliation(s)
- Kolawole O. Falade
- a Department of Food Technology , University of Ibadan , Ibadan , Nigeria
| | - John O. Akingbala
- b Food Science and Technology Unit, Department of Chemical Engineering , The University of the West Indies , St Augustine , Trinidad and Tobago
| |
Collapse
|
23
|
Adamolekun B. Etiology of Konzo, epidemic spastic paraparesis associated with cyanogenic glycosides in cassava: Role of thiamine deficiency? J Neurol Sci 2010; 296:30-3. [DOI: 10.1016/j.jns.2010.06.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2010] [Revised: 05/25/2010] [Accepted: 06/16/2010] [Indexed: 11/17/2022]
|
24
|
Chabwine JN, Masheka C, Balol'ebwami Z, Maheshe B, Balegamire S, Rutega B, Wa Lola M, Mutendela K, Bonnet MJ, Shangalume O, Balegamire JM, Nemery B. Appearance of konzo in South-Kivu, a wartorn area in the Democratic Republic of Congo. Food Chem Toxicol 2010; 49:644-9. [PMID: 20691241 DOI: 10.1016/j.fct.2010.07.050] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 06/22/2010] [Accepted: 07/29/2010] [Indexed: 10/19/2022]
Abstract
Konzo is an upper motor neuron disease characterized by sudden-onset and irreversible spastic paraparesis occurring in nutritionally compromised people. It is associated with consumption of insufficiently processed cyanogenic-toxic cassava. Cassava, the main caloric source in the Democratic Republic of Congo, has been safely consumed for decades in the Eastern Province of South-Kivu. However, in the context of long-lasting war and violent conflicts, cases of spastic paraparesis resembling konzo appeared in a populous area (Burhinyi). Two field surveys (2003 and 2005) identified 41 subjects meeting clinical criteria of konzo and suffering from (chronic) malnutrition. Their urinary thiocyanate concentrations (median 129, range 20-688, SD 146 μg/L), and cyanogen levels (median 20 ppm, range 5-300 ppm, SD 73 ppm) in cassava roots from their household stocks were high. The source of cyanogenic-toxicity was unprocessed fresh cassava roots during harvest period, but probably also insufficiently processed roots. This first report of konzo in South-Kivu concludes that occurrence of konzo was triggered by food shortages because of the longstanding state of insecurity. Contributory factors included the introduction of new varieties of (bitter) cassava, but konzo may actually be caused by a combination of factors that are yet to be understood.
Collapse
Affiliation(s)
- J N Chabwine
- Faculty of Medicine, Université Catholique de Bukavu, PO Box 02, Cyangugu, Rwanda
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
25
|
Cliff J, Muquingue H, Nhassico D, Nzwalo H, Bradbury JH. Konzo and continuing cyanide intoxication from cassava in Mozambique. Food Chem Toxicol 2010; 49:631-5. [PMID: 20654676 DOI: 10.1016/j.fct.2010.06.056] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2010] [Revised: 06/16/2010] [Accepted: 06/18/2010] [Indexed: 11/26/2022]
Abstract
In Mozambique, epidemics of the cassava-associated paralytic disease, konzo, have been reported in association with drought or war: over 1100 cases in 1981, over 600 cases in 1992-1993, and over 100 cases in 2005. Smaller epidemics and sporadic cases have also been reported. Large epidemics have occurred at times of agricultural crisis, during the cassava harvest, when the population has been dependent on a diet of insufficiently processed bitter cassava. Konzo mostly affects women of child-bearing age and children over 2 years of age. When measured, serum or urinary thiocyanate concentrations, indicative of cyanide poisoning, have been high in konzo patients during epidemics and in succeeding years. Monitoring of urinary thiocyanate concentrations in schoolchildren in konzo areas has shown persistently high concentrations at the time of the cassava harvest. Inorganic sulphate concentrations have been low during and soon after epidemics. Programmes to prevent konzo have focused on distributing less toxic varieties of cassava and disseminating new processing methods, such as grating and the flour wetting method. Attention should be given to the wider question of agricultural development and food security in the regions of Africa where dependence on bitter cassava results in chronic cyanide intoxication and persistent and emerging konzo.
Collapse
Affiliation(s)
- J Cliff
- Department of Community Health, Faculty of Medicine, Universidade Eduardo Mondlane, Maputo, Mozambique.
| | | | | | | | | |
Collapse
|
26
|
Konzo outbreak among refugees from Central African Republic in Eastern region, Cameroon. Food Chem Toxicol 2010; 49:579-82. [PMID: 20538034 DOI: 10.1016/j.fct.2010.05.081] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2009] [Revised: 05/07/2010] [Accepted: 05/31/2010] [Indexed: 11/22/2022]
Abstract
Konzo is a spastic paraparesis of sudden onset, linked to the exclusive consumption of insufficiently processed bitter cassava as staple food combined with low protein intake. Around 60,000 refugees from the Central African Republic sought refuge in villages in eastern Cameroon between 2005 and 2007. Médecins Sans Frontières was providing nutritional and medical assistance in the villages affected by displacement. We describe cases of konzo seen at the mobile clinics organized in these villages. Basic information including demographic data, history and clinical presentation was recorded for each konzo patient. All patients were given nutritional supplements, and selected cases were referred for physiotherapy to a rehabilitation center. A total of 469 patients were diagnosed with konzo. The majority (80%) were refugees. Children and women of reproductive age predominated. Most of the patients developed symptoms after 2007 in a seasonal pattern with most of the cases occurring during the dry winter season. Most of the patients complained about walking difficulties and weight loss and had exaggerated lower limb reflexes and muscle wasting on observation. Eastern Cameroon is an area with konzo. More effort needs to be put into preventive and educational measures. In addition, timely balanced food rations have to be provided to refugees.
Collapse
|
27
|
Kassa RM, Kasensa NL, Monterroso VH, Kayton RJ, Klimek JE, David LL, Lunganza KR, Kayembe KT, Bentivoglio M, Juliano SL, Tshala-Katumbay DD. On the biomarkers and mechanisms of konzo, a distinct upper motor neuron disease associated with food (cassava) cyanogenic exposure. Food Chem Toxicol 2010; 49:571-8. [PMID: 20538033 DOI: 10.1016/j.fct.2010.05.080] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Revised: 05/18/2010] [Accepted: 05/19/2010] [Indexed: 12/29/2022]
Abstract
Konzo is a self-limiting central motor-system disease associated with food dependency on cassava and low dietary intake of sulfur amino acids (SAA). Under conditions of SAA-deficiency, ingested cassava cyanogens yield metabolites that include thiocyanate and cyanate, a protein-carbamoylating agent. We studied the physical and biochemical modifications of rat serum and spinal cord proteins arising from intoxication of young adult rats with 50-200mg/kg linamarin, or 200mg/kg sodium cyanate (NaOCN), or vehicle (saline) and fed either a normal amino acid- or SAA-deficient diet for up to 2 weeks. Animals under SAA-deficient diet and treatment with linamarin or NaOCN developed hind limb tremors or motor weakness, respectively. LC/MS-MS analysis revealed differential albumin carbamoylation in animals treated with NaOCN, vs. linamarin/SAA-deficient diet, or vehicle. 2D-DIGE and MALDI-TOF/MS-MS analysis of the spinal cord proteome showed differential expression of proteins involved in oxidative mechanisms (e.g. peroxiredoxin 6), endocytic vesicular trafficking (e.g. dynamin 1), protein folding (e.g. protein disulfide isomerase), and maintenance of the cytoskeleton integrity (e.g. α-spectrin). Studies are needed to elucidate the role of the aformentioned modifications in the pathogenesis of cassava-associated motor-system disease.
Collapse
Affiliation(s)
- Roman M Kassa
- Center for Research on Occupational and Environmental Toxicology, Oregon Health and Science University, Portland, OR, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Chemical ecology in coupled human and natural systems: people, manioc, multitrophic interactions and global change. CHEMOECOLOGY 2010. [DOI: 10.1007/s00049-010-0047-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
29
|
Soler-Martín C, Riera J, Seoane A, Cutillas B, Ambrosio S, Boadas-Vaello P, Llorens J. The targets of acetone cyanohydrin neurotoxicity in the rat are not the ones expected in an animal model of konzo. Neurotoxicol Teratol 2009; 32:289-94. [PMID: 19932169 DOI: 10.1016/j.ntt.2009.11.001] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Revised: 11/12/2009] [Accepted: 11/12/2009] [Indexed: 11/30/2022]
Abstract
Konzo is a neurotoxic motor disease caused by excess consumption of insufficiently processed cassava. Cassava contains the cyanogenic glucoside linamarin, but konzo does not present the known pathological effects of cyanide. We hypothesized that the aglycone of linamarin, acetone cyanohydrin, may be the cause of konzo. This nitrile rapidly decomposes into cyanide and acetone, but the particular exposure and nutrition conditions involved in the emergence of konzo may favor its stabilization and subsequent acute neurotoxicity. A number of preliminary observations were used to design an experiment to test this hypothesis. In the experiment, young female Long-Evans rats were given 10mM acetone cyanohydrin in drinking water for 2 weeks, and then 20mM for 6 weeks. Nutrition deficits associated with konzo were modeled by providing tapioca (cassava starch) as food for the last 3 of these weeks. After this period, rats were fasted for 24h in order to increase endogenous acetone synthesis, and then exposed to 0 (control group) or 50 micromol/kg-h of acetone cyanohydrin for 24h (treated group) through subcutaneous osmotic minipump infusion (n=6/group). Motor activity and gait were evaluated before exposure (pre-test), and 1 and 6 days after exposure. Brains (n=4) were stained for neuronal degeneration by fluoro-jade B. Rats exposed to 50 micromol/kg-h of acetone cyanohydrin showed acute signs of toxicity, but no persistent motor deficits. Two animals showed fluoro-jade staining in discrete thalamic nuclei, including the paraventricular and the ventral reuniens nuclei; one also exhibited labeling of the dorsal endopiriform nucleus. Similar effects were not elicited by equimolar KCN exposure. Therefore, acetone cyanohydrin may cause selective neuronal degeneration in the rat, but the affected areas are not those expected in an animal model of konzo.
Collapse
Affiliation(s)
- Carla Soler-Martín
- Departament de Ciències Fisiològiques II, Universitat de Barcelona, 08907 Hospitalet de Llobregat, Spain
| | | | | | | | | | | | | |
Collapse
|
30
|
Résurgence de la maladie de konzo dans la région sanitaire no 2 en République centrafricaine. Rev Neurol (Paris) 2009; 165:466-70. [DOI: 10.1016/j.neurol.2008.10.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Revised: 09/04/2008] [Accepted: 10/08/2008] [Indexed: 11/18/2022]
|
31
|
Ghorbel H, Fetoui H, Mahjoubi A, Guermazi F, Zeghal N. Thiocyanate effects on thyroid function of weaned mice. C R Biol 2008; 331:262-71. [DOI: 10.1016/j.crvi.2008.01.010] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 01/17/2008] [Accepted: 01/30/2008] [Indexed: 11/26/2022]
|
32
|
Chapter 18 Toxic disorders of the upper motor neuron system. HANDBOOK OF CLINICAL NEUROLOGY 2007; 82:353-72. [DOI: 10.1016/s0072-9752(07)80021-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
|
33
|
Cardoso A, Mirione E, Ernesto M, Massaza F, Cliff J, Rezaul Haque M, Bradbury J. Processing of cassava roots to remove cyanogens. J Food Compost Anal 2005. [DOI: 10.1016/j.jfca.2004.04.002] [Citation(s) in RCA: 148] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
34
|
Mwanza JC, Tshala-Katumbay D, Tylleskär T. Neuro-ophthalmologic manifestations of konzo. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2005; 19:491-496. [PMID: 21783517 DOI: 10.1016/j.etap.2004.12.012] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Konzo is a permanent spastic paraparesis of acute onset attributed to the effect of cyanogenic compounds from insufficiently processed bitter cassava in combination with low protein intake. In all studies of konzo, ophthalmologic complaints have been presented but only recently systematic studies of the neuro-ophthalmologic disturbances in konzo have been done. In this review, we see that about half the patients have an optic neuropathy with decreased visual acuity, alterations of the visual fields, atrophy of the temporal part of the retinal nerve fibre layer linked with temporal pallor of the optic disk. About half of the konzo patients also have abnormal visual evoked potentials, with both delayed latency and reduced amplitude. A small number of konzo patients have an ocular motor disturbance leading to a pendular nystagmus. The severity of the neuro-ophthalmologic involvement is not parallel to the severity of the motor disturbance in konzo. This may suggest that two different pathogenic mechanisms are involved.
Collapse
Affiliation(s)
- Jean-Claude Mwanza
- Department of Ophthalmology, Kinshasa University Hospital, Kinshasa, Congo
| | | | | |
Collapse
|
35
|
Abstract
Cyanogenic glucosides are naturally present in plant foods especially in staple foods (cassava) consumed by millions of people in tropical countries. Most traditional processing methods are effective in detoxifying such goitrogens to safe levels of consumption. Nevertheless, residual cyanide (CN) is rapidly metabolized to thiocyanate (SCN) by existing metabolic pathways. There are concerns that goitrogens may reach the nursing infants through breast feeding or cow's milk based formulas. SCN adverse effects are commonly observed in relation to cigarette smoking. Breast-feeding is effective in protecting infants from anti-thyroid effects of eventual or habitual maternal exposure to CN exposure in food (cassava) or recreation habits (cigarette smoking). SCN goitrogenic effects occur secondary to iodine deficiency in special circumstances of high consumption of incomplete detoxified cassava and insufficient protein intake. Only during inadequate protein nutrition can SCN aggravate endemic iodine-deficient disorders (IDD).
Collapse
Affiliation(s)
- Jose G Dorea
- Faculdade de Ciências da Saúde, Universidade de Brasília, Brasília, Brazil
| |
Collapse
|
36
|
Dórea JG. Cassava cyanogens and fish mercury are high but safely consumed in the diet of native Amazonians. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2004; 57:248-256. [PMID: 15041248 DOI: 10.1016/j.ecoenv.2003.12.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2003] [Revised: 11/17/2003] [Accepted: 12/08/2003] [Indexed: 05/24/2023]
Abstract
The two most important staple foods (cassava and fish) in the diet of native Amazonians contain neurotoxins (linamarin and monomethyl mercury, MMHg). These same neurotoxins are public health issues in other parts of the world. Factors such as chemistry, environment, and human ecology determine the endemism of neuropathies caused by consumption of cassava (Manihot esculenta Crantz) and fish. Linamarin is a natural component of cassava tubers that can be destroyed before consumption by proper processing. Furthermore, small amounts of the toxin absorbed by people consuming cassava can be effectively metabolized if the diet contains adequate protein-containing sulfur amino acids. Naturally occurring Hg in the waters of the Amazonian rain forest is methylated to MMHg by microorganisms and bioconcentrated in the aquatic food chain. There is no effective method for MMHg removal from fish. Despite high concentrations of naturally occurring neurotoxins in cassava (linamarin) and fish (MMHg), daily consumption of these foods in large amounts over the course of a lifetime poses no health hazards for Amazonians.
Collapse
Affiliation(s)
- José G Dórea
- Faculdade de Ciĉncias da Saúde, Universidade de Brasília, Brasília, Brazil.
| |
Collapse
|
37
|
Enfermedades neurológicas asociadas al consumo de variedades de mandioca con alto contenido en gluconitrilos. ACTA ACUST UNITED AC 2004. [DOI: 10.1016/s1575-0922(04)74638-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
38
|
Ernesto M, Cardoso AP, Nicala D, Mirione E, Massaza F, Cliff J, Haque MR, Bradbury JH. Persistent konzo and cyanogen toxicity from cassava in northern Mozambique. Acta Trop 2002; 82:357-62. [PMID: 12039675 DOI: 10.1016/s0001-706x(02)00042-6] [Citation(s) in RCA: 102] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We aimed to detect new cases of konzo and monitor cyanogen exposure from cassava flour in communities previously affected by konzo epidemics in Nampula Province, northern Mozambique. Other objectives were to detect subclinical upper motor neuron damage in schoolchildren and test a new kit to measure urinary thiocyanate concentration. In 1999 and 2000, we carried out active and passive case detection for konzo in Memba and Mogincual Districts. In July and October, 1999, we collected cassava flour from 30 houses in three communities and measured cyanogen concentrations with a picrate kit. In October 1999, we examined all schoolchildren in three communities for ankle clonus and measured urinary thiocyanate concentration in thirty schoolchildren in each of five communities with a picrate kit. We found 27 new cases of konzo in Mogincual District. Mean total cyanogen concentrations in cassava flour varied between both seasons and years, but were always high, ranging from 26 to 186 ppm. Very high mean levels at three sites in November 1998 and July 1999 were probably due to low rainfall in the 1997-1998 season. The proportion of schoolchildren with ankle clonus varied from 8 to 17%. The new picrate kit for urinary thiocyanate worked well; mean concentrations in schoolchildren ranged from 225 to 384 micromol x l(-1). Konzo and sub-clinical upper motor neuron damage persist in poor rural communities in northern Mozambique, associated with high cyanogen concentrations in cassava flour and high urinary thiocyanate concentrations in schoolchildren.
Collapse
Affiliation(s)
- Mario Ernesto
- Direcção Provincial da Saúde, CP 14, Nampula, Mozambique
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Tshala-Katumbay D, Edebol Eeg-Olofsson K, Kazadi-Kayembe T, Fällmar P, Tylleskär T, Kayembe-Kalula T. Abnormalities of somatosensory evoked potentials in konzo--an upper motor neuron disorder. Clin Neurophysiol 2002; 113:10-5. [PMID: 11801419 DOI: 10.1016/s1388-2457(01)00705-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
OBJECTIVE To determine whether the somatosensory pathways are involved or not in konzo. METHODS In 1998, 21 konzo subjects (15 females and 6 males; mean age 21 years) underwent a SEP study with a two-channel-equipment (Medtronic Keypoint, Denmark) whereas in 2000, 15 subjects (7 females and 8 males; mean age 21 years) participated in a study with a 4-channel-equipment. RESULTS Most subjects (19/21 in 1998 and 12/15 in 2000) showed normal median SEPs. The remainders had no median cortical responses. All 21 subjects in 1998 and 9 out of 15 in 2000 showed abnormalities of tibial SEPs mainly consisting of absence of cortical responses, prolonged cortical latencies, and central sensory delay to the lumbar spine. Most subjects showed normal absolute latencies both at peripheral and spinal levels. The SEP findings did not correlate with the severity, neither the duration of konzo, nor the experience or not of sensory symptoms at the onset of the disease. CONCLUSION Our findings are not specific of konzo. However, they suggest involvement of intracranial somatosensory pathways and point to similarities with other motor neuron diseases.
Collapse
|
40
|
Cyanogens in Cassava Flour and Roots and Urinary Thiocyanate Concentration in Mozambique. J Food Compost Anal 2000. [DOI: 10.1006/jfca.1999.0847] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
41
|
Andersen MD, Busk PK, Svendsen I, Møller BL. Cytochromes P-450 from cassava (Manihot esculenta Crantz) catalyzing the first steps in the biosynthesis of the cyanogenic glucosides linamarin and lotaustralin. Cloning, functional expression in Pichia pastoris, and substrate specificity of the isolated recombinant enzymes. J Biol Chem 2000; 275:1966-75. [PMID: 10636899 DOI: 10.1074/jbc.275.3.1966] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The first committed steps in the biosynthesis of the two cyanogenic glucosides linamarin and lotaustralin in cassava are the conversion of L-valine and L-isoleucine, respectively, to the corresponding oximes. Two full-length cDNA clones that encode cytochromes P-450 catalyzing these reactions have been isolated. The two cassava cytochromes P-450 are 85% identical, share 54% sequence identity to CYP79A1 from sorghum, and have been assigned CYP79D1 and CYP79D2. Functional expression has been achieved using the methylotrophic yeast, Pichia pastoris. The amount of CYP79D1 isolated from 1 liter of P. pastoris culture exceeds the amounts that putatively could be isolated from 22,000 grown-up cassava plants. Each cytochrome P-450 metabolizes L-valine as well as L-isoleucine consistent with the co-occurrence of linamarin and lotaustralin in cassava. CYP79D1 was isolated from P. pastoris. Reconstitution in lipid micelles showed that CYP79D1 has a higher k(c) value with L-valine as substrate than with L-isoleucine, which is consistent with linamarin being the major cyanogenic glucoside in cassava. Both CYP79D1 and CYP79D2 are present in the genome of cassava cultivar MCol22 in agreement with cassava being allotetraploid. CYP79D1 and CYP79D2 are actively transcribed, and production of acyanogenic cassava plants would therefore require down-regulation of both genes.
Collapse
Affiliation(s)
- M D Andersen
- Plant Biochemistry Laboratory, Department of Plant Biology, Royal Veterinary and Agricultural University, Copenhagen, Denmark
| | | | | | | |
Collapse
|