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Sanchez-Padilla E, Grais RF, Guerin PJ, Steele AD, Burny ME, Luquero FJ. Burden of disease and circulating serotypes of rotavirus infection in sub-Saharan Africa: systematic review and meta-analysis. THE LANCET. INFECTIOUS DISEASES 2009; 9:567-76. [DOI: 10.1016/s1473-3099(09)70179-3] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Aminu M, Esona MD, Geyer A, Steele AD. Epidemiology of rotavirus and astrovirus infections in children in northwestern Nigeria. Ann Afr Med 2009; 7:168-74. [PMID: 19623918 DOI: 10.4103/1596-3519.55658] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND Recent estimates attribute 527,000 deaths in children less than five years of age to rotavirus diarrhea annually, with 145,000 occurring in sub-Saharan Africa. Human astroviruses have been identified as one of the most frequent causes of infantile diarrhea, second in incidence only to rotavirus. This study was conducted to determine the prevalence of rotavirus and astrovirus and also to establish the circulating strains of rotavirus in a community in Nigeria where most diarrheic patients do not visit clinics or health care centers. METHODS A total of 154 stool samples (134 diarrheic and 20 non-diarrheic) were collected from infants and young children less than 5 years of age from January-March 2002. Samples were obtained by house-to-house visit in randomly selected districts in Zaria, Northwestern Nigeria. The samples were screened for rotavirus and astrovirus antigens using commercially available Enzyme Linked Immunosorbent Assay (ELISA) kits. All positive group A rotavirus samples were further subjected to VP6 sub-group ELISA, Polyacrylamide gel electrophoresis (PAGE) to determine their RNA electropherotypes and Reverse transcription polymerase chain reaction (RT-PCR) to determine their VP7 and VP4 genotypes. RESULTS Rotavirus and astrovirus antigens were detected in 9% (12) and 5% (7) of the 134 diarrheic stool samples respectively. No viral antigen was detected in the non-diarrheic stools. Rotavirus infection was more common in younger children than astrovirus infection. VP6 sub-group II specificity (58.3%), long RNA electropherotypes (41.6%), VP7 genotype G1 (33.3%) and VP4 genotype P [6] (33.3%) were the most common strains in circulation at that time in the community. Of significance is the fact that a large proportion of the rotavirus strains in circulation could not be assigned either a VP6 subgroup or RNA electrophoretic pattern probably as a result of low viral load. CONCLUSION In this community-based study, rotavirus and astrovirus were significantly associated with diarrhea. However, the prevalence of rotavirus infection among children appears to be low while that of astrovirus falls in the range seen in hospital-based studies around the continent.
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Abstract
Inactivation of mahogunin, an E3 ubiquitin ligase, causes a spongiform encephalopathy resembling prion disease. Chakrabarti and Hegde (2009) now report that prion proteins with aberrant topologies inactivate mahogunin, providing a plausible explanation for certain aspects of prion pathology.
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Aminu M, Ameh EA, Geyer A, Esona MD, Taylor MB, Steele AD. Role of astrovirus in intussusception in Nigerian infants. J Trop Pediatr 2009; 55:192-4. [PMID: 19052076 DOI: 10.1093/tropej/fmn101] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Intussusception (IS) is a form of intestinal obstruction in which a segment of the bowel prolapses into a more distal segment. Viral infections, mostly adenovirus, enteroviruses, human herpesvirus and Epstein-Barr virus are reported in 20-50% of childhood cases of IS. Between January and July 2004, six stool specimens collected from infants 0- to 8-months old diagnosed and admitted for IS were investigated for the presence of rotavirus, astrovirus and adenovirus antigens. Astrovirus antigen was detected in three of the six stool specimens by enzyme immune assay (EIA) and confirmed in two specimens by reverse transcription-polymerase chain reaction (RT-PCR). Rotavirus, non-enteric adenovirus and astrovirus were detected by EIA, as mixed infections in a single specimen. The rotavirus strain revealed a SGI+II, mixed G1G2G8P[6] genotype and had no visible electrophoretic profile. A larger study is needed to determine the extent of involvement of astroviruses in IS in infants and the virus should be included in studies investigating the aetiology of IS.
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Kiulia NM, Kamenwa R, Irimu G, Nyangao JO, Gatheru Z, Nyachieo A, Steele AD, Mwenda JM. The epidemiology of human rotavirus associated with diarrhoea in Kenyan children: a review. J Trop Pediatr 2008; 54:401-5. [PMID: 18593738 DOI: 10.1093/tropej/fmn052] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Rotavirus gastroenteritis still remains a major cause of morbidity and mortality among young children in developing countries, with approximately 150,000-200,000 deaths occurring annually in sub-Saharan Africa. We reviewed papers published over the last 30 years on the epidemiology of rotavirus diarrhoea among the hospitalized and out-patient children in Kenya. The analysis shows rotavirus prevalence of 6-56% with diarrhoea occurring throughout the year and generally exhibiting distinct peaks during the dry months. Among the common genotype, G1 was the most predominant up to the year 2002 but more recently there has been an emergence of genotype G9 as the most predominant genotype and to a less extent G8. It is important to continue rotavirus surveillance in Kenya to determine accurately the burden of rotavirus disease and the emerging new genotypes. This will assist policy makers in decision making on rotavirus vaccine introduction and determining the impact of the vaccine.
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Aminu M, Ahmad AA, Umoh JU, Dewar J, Esona MD, Steele AD. Epidemiology of rotavirus infection in north-western Nigeria. J Trop Pediatr 2008; 54:340-2. [PMID: 18344546 DOI: 10.1093/tropej/fmn021] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Rotaviruses (RV) are associated with approximately 33 000 deaths in children <5 years of age annually in Nigeria. However, limited data exit on RV infection in north-western Nigeria. During July 2002 to July 2004, 1063 (869 diarrhoeic and 194 control) stool samples were collected from children <5 years of age presenting with diarrhoea in north-western Nigeria. The stools were analysed for RV antigen and further characterized by antigenic and genomic methods. RV was detected in 18% of children with diarrhoea and 7.2% of the age-matched case controls. The highest RV burden was detected in children <6-months-old. Long electropherotypes and VP6 subgroup I + II specificity predominated.
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Chen D, Steele AD, Hutter G, Bruno J, Govindarajan A, Easlon E, Lin SJ, Aguzzi A, Lindquist S, Guarente L. The role of calorie restriction and SIRT1 in prion-mediated neurodegeneration. Exp Gerontol 2008; 43:1086-93. [PMID: 18799131 DOI: 10.1016/j.exger.2008.08.050] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 08/20/2008] [Accepted: 08/21/2008] [Indexed: 10/21/2022]
Abstract
A central focus of aging research is to determine how calorie restriction (CR) extends lifespan and delays diseases of aging. SIRT1, the mammalian ortholog of Sir2 in yeast, is a longevity factor which mediates dietary restriction in diverse species. In addition, SIRT1 plays a protective role in several models of neurodegenerative disease. We tested the role of SIRT1 in mediating the effects of CR in a mouse model of prion disease. Prion diseases are protein misfolding disorders of the central nervous system with many similarities to other neurodegenerative diseases, including deposition of aggregated protein, gliosis, and loss of synapses and neurons. We report that the onset of prion disease is delayed by CR and in the SIRT1 KO mice fed ad libitum. CR exerts no further effect on the SIRT1 KO strain, suggesting the effects of CR and SIRT1 deletion are mechanistically coupled. In conjunction, SIRT1 is downregulated in certain brain regions of CR mice. The expression of PrP mRNA and protein is reduced in the brains of CR mice and in SIRT1 knockout mice, suggesting a possible mechanism for the delayed onset of disease, as PrP levels are a critical determinant of how quickly mice succumb to prion disease. Surprisingly, CR greatly shortens the duration of clinical symptoms of prion disease and ultimately shortens lifespan of prion-inoculated mice in a manner that is independent of SIRT1. Taken together, our results suggest a more complex interplay between CR, SIRT1, and neurodegenerative diseases than previously appreciated.
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Steele AD. All quiet on the neuronal front: NMDA receptor inhibition by prion protein. J Gen Physiol 2008; 131:i3. [PMID: 18504309 DOI: 10.1085/jgp1316oia3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The normal function of the prion protein (PrP)--the causative agent of mad cow or prion disease--has long remained out of reach. Deciphering PrP's function may help to unravel the complex chain of events triggered by PrP misfolding during prion disease. In this issue of the JCB, an exciting paper (Khosravani, H., Y. Zhang, S. Tsutsui, S. Hameed, C. Altier, J. Hamid, L. Chen, M. Villemaire, Z. Ali, F.R. Jirik, and G.W. Zamponi. 2008. J. Cell Biol. 181:551-565) connects diverse observations regarding PrP into a coherent framework whereby PrP dampens the activity of an N-methyl-D-aspartate (NMDA) receptor (NMDAR) subtype and reduces excitotoxic lesions. The findings of this study suggest that understanding the normal function of proteins associated with neurodegenerative disease may elucidate the molecular pathogenesis.
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Steele AD. All quiet on the neuronal front: NMDA receptor inhibition by prion protein. J Exp Med 2008. [DOI: 10.1084/jem2055oia14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Abstract
The normal function of the prion protein (PrP)—the causative agent of mad cow or prion disease—has long remained out of reach. Deciphering PrP's function may help to unravel the complex chain of events triggered by PrP misfolding during prion disease. In this issue of the JCB, an exciting paper (Khosravani, H., Y. Zhang, S. Tsutsui, S. Hameed, C. Altier, J. Hamid, L. Chen, M. Villemaire, Z. Ali, F.R. Jirik, and G.W. Zamponi. 2008. J. Cell Biol. 181:551–565) connects diverse observations regarding PrP into a coherent framework whereby PrP dampens the activity of an N-methyl-d-aspartate (NMDA) receptor (NMDAR) subtype and reduces excitotoxic lesions. The findings of this study suggest that understanding the normal function of proteins associated with neurodegenerative disease may elucidate the molecular pathogenesis.
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Dzikwi AA, Umoh JU, Kwaga JKP, Ahmad AA, deBeer M, Steele AD. Electropherotypes and subgroups of group A rotaviruses circulating among diarrhoeic children in Kano, Nigeria. Ann Afr Med 2008; 7:163-7. [DOI: 10.4103/1596-3519.55659] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Bordone L, Cohen D, Robinson A, Motta MC, van Veen E, Czopik A, Steele AD, Crowe H, Marmor S, Luo J, Gu W, Guarente L. SIRT1 transgenic mice show phenotypes resembling calorie restriction. Aging Cell 2007; 6:759-67. [PMID: 17877786 DOI: 10.1111/j.1474-9726.2007.00335.x] [Citation(s) in RCA: 520] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We generated mice that overexpress the sirtuin, SIRT1. Transgenic mice have been generated by knocking in SIRT1 cDNA into the beta-actin locus. Mice that are hemizygous for this transgene express normal levels of beta-actin and higher levels of SIRT1 protein in several tissues. Transgenic mice display some phenotypes similar to mice on a calorie-restricted diet: they are leaner than littermate controls; are more metabolically active; display reductions in blood cholesterol, adipokines, insulin and fasted glucose; and are more glucose tolerant. Furthermore, transgenic mice perform better on a rotarod challenge and also show a delay in reproduction. Our findings suggest that increased expression of SIRT1 in mice elicits beneficial phenotypes that may be relevant to human health and longevity.
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Steele AD, Hetz C, Yi CH, Jackson WS, Borkowski AW, Yuan J, Wollmann RH, Lindquist S. Prion pathogenesis is independent of caspase-12. Prion 2007; 1:243-7. [PMID: 19164919 PMCID: PMC2634538 DOI: 10.4161/pri.1.4.5551] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The pathogenic mechanism(s) underlying neurodegenerative diseases associated with protein misfolding is unclear. Several studies have implicated ER stress pathways in neurodegenerative conditions, including prion disease, amyotrophic lateral sclerosis, Alzheimer's disease and many others. The ER stress response and upregulation of ER stress-responsive chaperones is observed in the brains of patients affected with Creutzfeldt-Jacob disease and in mouse models of prion diseases. In particular, the processing of caspase-12, an ER-localized caspase, correlates with neuronal cell death in prion disease. However, the contribution of caspase-12 to neurodegeneration has not been directly addressed in vivo. We confirm that ER stress is induced and that caspase-12 is proteolytically processed in a murine model of infectious prion disease. To address the causality of caspase-12 in mediating infectious prion pathogenesis, we inoculated mice deficient in caspase-12 with prions. The survival, behavior, pathology and accumulation of proteinase K-resistant PrP are indistinguishable between caspase-12 knockout and control mice, suggesting that caspase-12 is not necessary for mediating the neurotoxic effects of prion protein misfolding.
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Akoua-Koffi C, Akran V, Peenze I, Adjogoua V, de Beer MC, Steele AD, Dosso M, Ehouman A. [Epidemiological and virological aspects Rotavirus diarrhoea in Abidjan, Côte d'Ivoire (1997-2000)]. BULLETIN DE LA SOCIETE DE PATHOLOGIE EXOTIQUE (1990) 2007; 100:246-249. [PMID: 17982852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Viruses, mainly rotaviruses are aetiological agents in more than 80% of the cases of acute diarrhoea in children. In order to determine the epidemiological characteristics and genotypes of human rotaviruses involved in gastroenteritis in diarrheic children aged from 0 to 5 years old in Abidjan, 642 specimens of stools were collected between 1997 and 2000 in the urban health centres and University Teaching Hospitals in Abidjan. The antigenic detection of rotaviruses carried out by ELISA test was followed by the antigenic (VP6 sub-groups) and molecular characterization: polyacrylamide gel electrophoresis and genetic typing. The general prevalence of Rotavirus diarrhoea was 27.9%. Among the children who were found positive, those whose age ranged from 0 to 11 months old accounted for 45.8% against 41.3% and 12.9% for those whose age ranged from 1 to 2 and 3 to 5 years old respectively proving thus the precocity of rotavirus infection. From an electrophoretypical and antigenic point of view 74.5% of 141 extracts of RNA had a "long" profile and belonged to the VP6 II sub-group against 24.8% of "short" profile belonging to sub-group I. The electrophoretypes with short profile were identified in majority in infants whose age ranged from 0 to 2 years old. Out of the P genotypes identified, the P [8] genotype (59.6%) was predominant followed by the P [6] genotype (26.2%), P [4] (2.8%) and one mosaic genotype P[6,8] which represented 11.4%. These results will need to be completed by the determination of VP7 genotypes in order to provide interesting information on rotaviruses before the introduction of anti-Rotavirus vaccines in the country.
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Chouikha A, Fodha I, Noomen S, Bouzid L, Mastouri M, Peenze I, De Beer M, Dewar J, Geyer A, Sfar T, Gueddiche N, Messaadi F, Trabelsi A, Boujaafar N, Steele AD. Group A rotavirus strains circulating in the eastern center of Tunisia during a ten-year period (1995-2004). J Med Virol 2007; 79:1002-8. [PMID: 17516524 DOI: 10.1002/jmv.20919] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
An epidemiological survey investigating rotavirus infections in children was undertaken in the Eastern Center of Tunisia between January 1995 and December 2004. A total of 982 faecal specimens collected from children less than 5 years in age were screened by enzyme-linked immunosorbent assay (ELISA) or latex agglutination assay for the presence of group A rotavirus antigen. Rotavirus-positive samples were used for G and P typing by multiplex semi-nested reverse transcription-PCR. Rotaviruses were detected in 22% (n = 220) of stools. Of these, 164 were typed for VP7: G genotypes found were G1 (59%), G2 (2%), G3 (9%), G4 (10%), G8 (1%), and G9 (1%). Sixteen specimens (9%) showed mixed G profiles. A total of 119 specimens were typed for VP4. P genotypes detected were P[8] (32%), P[6] (15%), and P[4] (13%). Mixed P profiles were also detected (6%). Although the distribution of the detected genotypes appeared to change annually, G1P[8] rotavirus strains always predominated during the 10-year period of study. This is the first report of rotaviruses in Tunisia with unconventional VP7 serotypes such as G8 and G9, highlighting the need for continual surveillance of emerging strains in Northern Africa. Indeed, the new commercial vaccines only contain the VP7 genes that dictate G1 or G1 to G4 specificities. These vaccines may protect less well against unusual strains circulating in countries planning to implement a rotavirus vaccine strategy.
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Kiulia NM, Mwenda JM, Nyachieo A, Nyaundi JK, Steele AD, Taylor MB. Astrovirus infection in young Kenyan children with diarrhoea. J Trop Pediatr 2007; 53:206-9. [PMID: 17308325 DOI: 10.1093/tropej/fml093] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Human astroviruses (HAstV) have been commonly identified worldwide as important aetiological agents of acute gastroenteritis in all age groups including the young, elderly and immunocompromised. However, limited data exist on the prevalence of this important pathogen in Kenya. The aim of this study was therefore to determine the prevalence of astrovirus (AstV) infection in Kenyan children younger than 10 years of age with diarrhoea. During the period February 1999 to September 2005, stool samples were collected from 476 children attending clinics in Nairobi (and its environs) and the Maua Methodist Hospital, Meru North, Kenya. The faecal specimens were tested by a commercial enzyme immunoassay kit for HAstV. AstV prevalence rates were found to be 6.3%. There was significantly high prevalence of AstV infection in children <or=5 years [5.3% (25/476)] than those >5 years [0.2% (1/476)] ( p < 0.01). Also, we showed a significantly high prevalence of AstV infection in children of <or=5 years [5.8% (20/341)] in Nairobi (urban setting) as compared with those of similar age in Maua (a rural setting) [3.7% (5/135)] ( p < 0.01). This study indicates that HAstV is an important pathogen associated with diarrhoea in young Kenyan children.
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Fodha I, Chouikha A, Dewar J, Trabelsi A, Boujaafar N, Steele AD. [Prevalence of adenovirus antigens in children presenting with acute diarrhoea]. MEDECINE TROPICALE : REVUE DU CORPS DE SANTE COLONIAL 2007; 67:256-8. [PMID: 17784677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Viral diarrhoea remains a major cause of childhood morbidity and mortality worldwide. Four major categories of viruses are now recognized as clinically important, including rotavirus, astrovirus, adenovirus, and calicivirus. This retrospective epidemiological study was conducted in the East centre part of Tunisia. A total of 638 stool samples were collected from children under 5 years of age presenting with acute diarrhoea at hospitals the East centre part of Tunisia between October 2003 and September 2005. All samples were analyzed using commercially available immunoenzymatic assay (EIA) kits to detect specific adenovirus antigens. Samples positive for adenovirus antigen were further screened using an ELISA technique allowing specific detection of species F enteric adenovirus types 40 and 41. Adenovirus was detected in 6% of the stools tested using ELISA. Among stool samples testing positive for adenovirus, 57% (20/35) were found to contain species F adenovirus types 40/41. In addition to diarrhoea that was present in all children studied, vomiting and fever were observed in 89% and 53% respectively and were associated with respiratory troubles in 32%. Enteric adenoviruses appear to play an important role in paediatric diarrhoea in Tunisia. Use of simple effective viral diagnostic techniques in paediatric hospitals could improve patient care by reducing unnecessary use of antibiotics.
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Steele AD, Lindquist S, Aguzzi A. The prion protein knockout mouse: a phenotype under challenge. Prion 2007; 1:83-93. [PMID: 19164918 DOI: 10.4161/pri.1.2.4346] [Citation(s) in RCA: 118] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The key pathogenic event in prion disease involves misfolding and aggregation of the cellular prion protein (PrP). Beyond this fundamental observation, the mechanism by which PrP misfolding in neurons leads to injury and death remains enigmatic. Prion toxicity may come about by perverting the normal function of PrP. If so, understanding the normal function of PrP may help to elucidate the molecular mechansim of prion disease. Ablation of the Prnp gene, which encodes PrP, was instrumental for determining that the continuous production of PrP is essential for replicating prion infectivity. Since the structure of PrP has not provided any hints to its possible function, and there is no obvious phenotype in PrP KO mice, studies of PrP function have often relied on intuition and serendipity. Here, we enumerate the multitude of phenotypes described in PrP deficient mice, many of which manifest themselves only upon physiological challenge. We discuss the pleiotropic phenotypes of PrP deficient mice in relation to the possible normal function of PrP. The critical question remains open: which of these phenotypes are primary effects of PrP deletion and what do they tell us about the function of PrP?
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Steele AD, Jackson WS, King OD, Lindquist S. The power of automated high-resolution behavior analysis revealed by its application to mouse models of Huntington's and prion diseases. Proc Natl Acad Sci U S A 2007; 104:1983-8. [PMID: 17261803 PMCID: PMC1794260 DOI: 10.1073/pnas.0610779104] [Citation(s) in RCA: 141] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Automated analysis of mouse behavior will be vital for elucidating the genetic determinants of behavior, for comprehensive analysis of human disease models, and for assessing the efficacy of various therapeutic strategies and their unexpected side effects. We describe a video-based behavior-recognition technology to analyze home-cage behaviors and demonstrate its power by discovering previously unrecognized features of two already extensively characterized mouse models of neurodegenerative disease. The severe motor abnormalities in Huntington's disease mice manifested in our analysis by decreased hanging, jumping, stretching, and rearing. Surprisingly, behaviors such as resting and grooming were also affected. Unexpectedly, mice with infectious prion disease showed profound increases in activity at disease onset: rearing increased 2.5-fold, walking 10-fold and jumping 30-fold. Strikingly, distinct behaviors were altered specifically during day or night hours. We devised a systems approach for multiple-parameter phenotypic characterization and applied it to defining disease onset robustly and at early time points.
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Steele AD, Yi CH. Neuromuscular denervation: Bax up against the wall in amyotrophic lateral sclerosis. J Neurosci 2007; 26:12849-51. [PMID: 17171827 PMCID: PMC6674958 DOI: 10.1523/jneurosci.4086-06.2006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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Aminu M, Ahmad AA, Umoh JU, de Beer MC, Esona MD, Steele AD. Adenovirus infection in children with diarrhea disease in Northwestern Nigeria. Ann Afr Med 2007; 6:168-73. [DOI: 10.4103/1596-3519.55702] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
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Kiulia NM, Peenze I, Dewar J, Nyachieo A, Galo M, Omolo E, Steele AD, Mwenda JM. Molecular characterisation of the rotavirus strains prevalent in Maua, Meru North, Kenya. ACTA ACUST UNITED AC 2006; 83:360-5. [PMID: 17089495 DOI: 10.4314/eamj.v83i7.9447] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND Rotavirus is the most common cause of severe infantile diarrhoea disease in infants and young children below five years worldwide. Rotavirus is associated with high cases of morbidity and mortality and it is estimated that up to 650,000 deaths in young children occur annually in the less developed countries and approximately 150,000-200,000 deaths occur in Africa alone. OBJECTIVE To characterise the circulating rotavirus strains in Maua, Meru North district, Kenya. DESIGN A prospective study to investigate and characterise rotavirus serotypes/genotypes and electropherotypes in infants and children with severe diarrhoea hospitalised and/or attending the outpatient department of Maua Methodist Hospital during the period April 2004 to September 2005. SETTING Maua Methodist Hospital, Meru North, Kenya. SUBJECTS Faecal samples were collected from 135 infants and children with acute diarrhoea and were screened first for the presence of human Group A rotavirus antigen using commercially available enzyme linked immunosorbent assay kit (ELISA). The positive samples were evaluated by sodium dodecyl polycrylamide gel electrophoresis (SDS-PAGE) to determine the viral RNA electropherotype profile. Rotavirus strains were also genotyped using reverse transcriptase polymerase chain reaction (RT-PCR) of the VP7 gene. RESULTS Assay of these samples with commercial ELISA showed that 17.8% (24/135) were positive for group A rotavirus antigen. Twenty of these ELISA positive samples were also analysed by SDS-PAGE of which 75% (15/20) gave detectable electropherotype pattern with the long electropherotype being predominant 80.0% (12/15) followed by the short RNA profile 20.0% (2/ 15). Seventeen of the ELISA positive samples were genotyped for VP7 and the results showed that G9 was the most predominant genotype comprising 47.1% (8/17) followed by G8 29.4% (5/17), GI 17.4% (3/17) and the mixed genotype was G8/G9 5.9% (1/17). Most patients with rotavirus infection were of the age of 3 - 60 months, with 79% being less than 18 months old. CONCLUSION The overall prevalence of rotavirus infection in young children with diarrhoea hospitalised and/or attending the out-patient department of Maua Methodist Hospital was 17.8% with the predominant serotype being G9. These results show that rotavirus plays an important role in severe viral diarrhoea in young children in Maua Meru North district, Kenya. Furthermore, this high G9 rotavirus prevalence in Kenya may require vaccine trials to be held in Kenya so as to determine the efficacy of new rotavirus vaccine candidates that do not include the G9 serotype.
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van Zyl WB, Page NA, Grabow WOK, Steele AD, Taylor MB. Molecular epidemiology of group A rotaviruses in water sources and selected raw vegetables in southern Africa. Appl Environ Microbiol 2006; 72:4554-60. [PMID: 16820443 PMCID: PMC1489384 DOI: 10.1128/aem.02119-05] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Group A rotaviruses (RVs) are the most important cause of acute viral gastroenteritis in infants and young children. In this study raw and treated drinking water supplies at plants in two geographic areas, as well as selected irrigation water and corresponding raw vegetables in three regions of southern Africa, were screened for the presence of RVs using molecular techniques. Group A RVs were detected in 11.8% of partially treated and 1.7% of finally treated drinking water samples and in 14% of irrigation water samples and 1.7% of corresponding raw vegetable samples. Type-specific reverse transcriptase-PCR and sequence analysis revealed the presence of multiple types (G1, G2, G8, and G9) in irrigation water and single types (G1 or G3) in raw and treated drinking water. Group A RVs detected in all samples consisted of mixed P types (P[4], P[6], P[8], and P[9]), with P[6] predominating. The detection of types G8, G9, and P[6] reflects the emergence of these types in clinical infections. The similarity of environmental types to those in patients with clinical RV infections confirms the value of wastewater screening as a tool for assessing RVs circulating in communities, with the benefit of detecting types that cause both clinical and subclinical infections. The results provide new information on RV types in water and related environments and identify the potential risk of waterborne transmission. In addition, the presence of RVs in drinking water underlines shortcomings in quality specifications. These data provide valuable information regarding the prevalence of RVs in environmental sources, with important implications for vaccine development.
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Steele AD, Emsley JG, Özdinler PH, Lindquist S, Macklis JD. Prion protein (PrPc) positively regulates neural precursor proliferation during developmental and adult mammalian neurogenesis. Proc Natl Acad Sci U S A 2006; 103:3416-21. [PMID: 16492732 PMCID: PMC1413927 DOI: 10.1073/pnas.0511290103] [Citation(s) in RCA: 212] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The misfolding of the prion protein (PrP(c)) is a central event in prion diseases, yet the normal function of PrP(c) remains unknown. PrP(c) has putative roles in many cellular processes including signaling, survival, adhesion, and differentiation. Given the abundance of PrP(c) in the developing and mature mammalian CNS, we investigated the role of PrP(c) in neural development and in adult neurogenesis, which occurs constitutively in the dentate gyrus (DG) of the hippocampus and in the olfactory bulb from precursors in the subventricular zone (SVZ)/rostral migratory stream. In vivo, we find that PrP(c) is expressed immediately adjacent to the proliferative region of the SVZ but not in mitotic cells. In vivo and in vitro studies further find that PrP(c) is expressed in multipotent neural precursors and mature neurons but is not detectable in glia. Loss- and gain-of-function experiments demonstrate that PrP(c) levels correlate with differentiation of multipotent neural precursors into mature neurons in vitro and that PrP(c) levels positively influence neuronal differentiation in a dose-dependent manner. PrP(c) also increases cellular proliferation in vivo; in the SVZ, PrP(c) overexpresser (OE) mice have more proliferating cells compared with wild-type (WT) or knockout (KO) mice; in the DG, PrP(c) OE and WT mice have more proliferating cells compared with KO mice. Our results demonstrate that PrP(c) plays an important role in neurogenesis and differentiation. Because the final number of neurons produced in the DG is unchanged by PrP(c) expression, other factors must control the ultimate fate of new neurons.
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Zhang CC, Steele AD, Lindquist S, Lodish HF. Prion protein is expressed on long-term repopulating hematopoietic stem cells and is important for their self-renewal. Proc Natl Acad Sci U S A 2006; 103:2184-9. [PMID: 16467153 PMCID: PMC1413720 DOI: 10.1073/pnas.0510577103] [Citation(s) in RCA: 185] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Although the wild-type prion protein (PrP) is abundant and widely expressed in various types of tissues and cells, its physiological function(s) remain unknown, and PrP knockout mice do not exhibit overt and undisputed phenotypes. Here we showed that PrP is expressed on the surface of several bone marrow cell populations successively enriched in long-term (LT) hematopoietic stem cells (HSCs) using flow cytometry analysis. Affinity purification of the PrP-positive and -negative fractions from these populations, followed by competitive bone marrow reconstitution assays, shows that all LT HSCs express PrP. HSCs from PrP-null bone marrow exhibited impaired self-renewal in serial transplantation of lethally irradiated mouse recipients both in the presence and absence of competitors. When treated with a cell cycle-specific myelotoxic agent, the animals reconstituted with PrP-null HSCs exhibit increased sensitivity to hematopoietic cell depletion. Ectopic expression of PrP in PrP-null bone marrow cells by retroviral infection rescued the defective hematopoietic engraftment during serial transplantation. Therefore, PrP is a marker for HSCs and supports their self-renewal.
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