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choreoathetosis, therefore the two loci should be close to each other.4 Identification of the earwax locus could contribute to further anthropogenetic studies and to physiological and pathological understanding of apocrine-gland development. Contributors H Tomita designed and organised the study, obtained phenotypic information and DNA samples from family 1, did genotyping and linkage analysis of all the families, and wrote the report. K Yamada, M Ghadami, T Ogura, and Y Yanai obtained phenotypic information and DNA samples from one of the families, and did genotyping of this family. K Nakatomi, M Sadamatsu, A Masiu, and N Kato obtained phenotypic information and DNA samples from one of the families. N Niikawa organised and supervised the study, obtained phenotypic information and DNA samples from one of the families, and wrote the report.
Conflict of interest statement None declared.
Acknowledgments The project was funded by Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation. The sponsor of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report. 1 2 3 4
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Matsunaga E. The dimorphism in human normal cerumen. Ann Hum Genet 1962; 25: 273–86. Ibraimov AI. Cerumen phenotypes in certain populations of Eurasia and Africa. Am J Phys Anthropol 1991; 84: 209–11. Petrakis NL. Physiologic, biochemical, and cytologic aspects of nipple aspirate fluid. Breast Cancer Res Treat 1986; 8: 7–19. Tomita H, Nagamitsu S, Wakui K, et al. Paroxysmal kinesigenic choreoathetosis locus maps to chromosome 16p11·2-q12·1. Am J Hum Genet 1999; 65: 1688–97. Sadamatsu M, Masui A, Sakai T, Kunugi H, Nanko S, Kato N. Familial paroxysmal kinesigenic choreoathetosis: an electrophysiologic and genotypic analysis. Epilepsia 1999; 40: 942–49.
Department of Human Genetics, Nagasaki University School of Medicine, Nagasaki, and Core Research for Evolutional Science and Technology, Japan Science and Technology Corporation, Kawaguchi, Japan (H Tomita MD, K Yamada MD, M Ghadami MD, T Ogura, Y Yanai, N Niikawa MD); Second Department of Internal Medicine, Nagasaki University School of Medicine, Nagasaki (K Nakatomi MD); Health Service Center, University of Tokyo, Tokyo (M Sadamatsu MD); Department of Psychiatry, Shiga University of Medical Science, Otsu (A Masui MD); and Department of Neuropsychiatry, Faculty of Medicine, University of Tokyo, Tokyo (N Kato MD) Correspondence to: Dr Hiroaki Tomita, Department of Psychiatry and Human Behaviour, University of California Irvine, D346 MED SCI I, CA 92697-1675, USA (e-mail:
[email protected])
An epidemic Burkholderia cepacia complex strain identified in soil John J LiPuma, Theodore Spilker, Tom Coenye, Carlos F Gonzalez Life threatening infection with species of the Burkholderia cepacia complex frequently occurs as a result of cross infection among individuals with cystic fibrosis. Stringent infection control measures have decreased but not eliminated such infection in this vulnerable population, implying that non-patient reservoirs contribute to ongoing acquisition. However, strains common to both the natural environment and patients with cystic fibrosis have not yet been described. By use of various genotyping methods, we have identified from agricultural soil the B cepacia genomovar III strain that is most frequently recovered from cystic fibrosis patients in the mid-Atlantic region of the USA. This finding indicates that human pathogenic strains are not necessarily distinct from environmental strains, and might help explain ongoing human acquisition despite strict infection control measures.
Lancet 2002; 359: 2002–03 Species of the Burkholderia cepacia complex have long been recognised as important pathogens in people with cystic fibrosis, in whom respiratory tract infection is often refractory to antimicrobial therapy and associated with life threatening
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decline in pulmonary function. Infection in cystic fibrosis is commonly linked to interpatient spread of specific epidemic clones. Indeed, harsh infection control policies in cystic fibrosis centres have decreased, but not entirely eliminated, new acquisition of B cepacia complex. More recently, these species have also been recognised as opportunistic pathogens capable of causing nosocomial infection among debilitated patients who do not have cystic fibrosis.1 In these instances the source of infection is frequently not known. At the same time that optimal infection control measures have been sought to prevent human infection due to B cepacia complex, these species have also attracted considerable attention for their potential use both in the biocontrol of plant disease and the bioremediation of recalcitrant environmental xenobiotics.2 Some B cepacia complex strains have the capacity to degrade pollutants including organophosphorous insecticides, polychlorinated biphenyls (PCBs), and chlorinated ethenes such as trichloroethylene (TCE)—one of the world’s most widespread ground water contaminants. This capacity could be exploited in environmental clean-up programmes. Other strains may be used as biopesticides to antagonise soilborne fungi such as Pythium spp and Fusarium spp, phytopathogens with wide host range, worldwide distribution, and substantial economic impact. The notion that human pathogenic and environmental strains of B cepacia complex are clearly distinguishable has raised hopes that naturally occurring strains could be developed for commercial use. In fact, strains common to both patients with cystic fibrosis and the natural environment have been sought but none have yet been described. In an ongoing study we have used several bacterial genotyping methods to assess isolates recovered from patients with cystic fibrosis and environmental sources in order to understand better the potential reservoirs of human infection due to B cepacia complex. We analysed 175 B cepacia complex isolates recovered during two consecutive growing seasons (1999 and 2000) from organic soils in four agricultural fields (from two counties located about 200 miles apart in New York State) that had been planted with onions for several years. Species determination using both recA- and 16S rDNA-targeted PCR assays identified 38 of these as genomovar III, the species most frequently recovered from sputum culture of patients with cystic fibrosis.3 Genotyping analyses using repetitive extragenic palindromic PCR (rep-PCR) and randomly amplified polymorphic DNA (RAPD) typing showed that several of these genomovar III isolates were the same strain type. Computerassisted analyses of rep-PCR and RAPD profiles, using UPMGA based clustering and a 0·8 similarity coefficient cutoff,4 indicated that this strain type was the same as PHDC, the genomovar III strain recovered from nearly all cystic fibrosis patients who were infected with B cepacia complex in large treatment centres in the mid-Atlantic region of the US.5 PHDC contains neither BCESM nor cblA markers, both of which are features of ET12, the genomovar III strain that predominates among infected cystic fibrosis patients in Canada and the UK. To further assess clonality we examined recA and flagellin (fliC) genes, loci that have been used previously in phylogenetic assessment and strain typing of B cepacia complex species. Among a subset of eight PHDC soil isolates and ten PHDC isolates from sputum culture taken from patients with cystic fibrosis, the mean recA DNA sequence identity was 99·1%, and all had identical fliC RFLP profiles after digestion with each of five restriction enzymes (AluI, DdeI, HaeIII, MspI, RsaI). By contrast, recA DNA sequences of 22 other genomovar III isolates from unrelated cystic fibrosis patients or soil sources exhibited 93·9% to 98·1% identity to the recA sequence of PHDC strain AU1107, and 19 different fliC RFLP profiles. Although genomic macrorestriction analysis by
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Conflict of interest statement None declared.
Acknowledgments This work was supported by grants from the Cystic Fibrosis Foundation. The sponsors of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the report. 1 Holmes A, Nolan R, Taylor R, et al. An epidemic of Burkholderia cepacia transmitted between patients with and without cystic fibrosis. J Infect Dis 1999; 179: 1197–205. 2 Parke JL, Gurian-Sherman D. Diversity of the Burkholderia cepacia complex and implications for risk assessment of biocontrol strains. Ann Rev Phytopathol 2001; 39: 225–58. 3 LiPuma JJ, Spilker T, Gill L, Campbell PW, Liu L, Mahenthiralingam E. Disproportionate distribution of Burkholderia cepacia complex species and transmissibility factors in cystic fibrosis. Am J Respir Crit Care Med 2001; 164: 92–96. 4 Cho J-C, Tiedje JM. Biogeography and degree of endemicity of fluorescent Pseudomonas strains in soil. Appl Environ Microbiol 2000; 66: 5448–56. 5 Chen JS, Witzmann K, Spilker T, Fink R, LiPuma JJ. Endemicity and inter-city spread of Burkholderia cepacia genomovar III in cystic fibrosis. J Pediatr 2001; 139: 643–49.
Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, 8323 MSRB III, Box 0646, Ann Arbor, MI 48109, USA (J J LiPuma MD, T Spilker BS, T Coenye PhD); and Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX 77843, USA (C F Gonzalez PhD) Correspondence to: Dr J J LiPuma (e-mail:
[email protected])
Breastfeeding and lowering the risk of childhood obesity Julie Armstrong, John J Reilly, and the Child Health Information Team Isolate genotyping by SpeI macrorestriction digestion and pulsed field gel electrophoresis Lane A, size markers; lane B, CF sputum isolate AU1107; lane C, onion field soil isolate HI2424; lane D, unrelated genomovar III soil isolate included for contrast.
digestion with SpeI and pulsed field gel electrophoresis (PFGE) showed slight variations in banding profile among the onion field and CF PHDC isolates, some—eg, cystic fibrosis isolate AU1107 and onion field isolate HI2424, were identical (figure). Finally, PHDC clonal isolates from both cystic fibrosis patients and soil sources macerated onion tissue and contained an identical pehA gene (encoding a pectic hydrolase), phytopathogenic features infrequently found among genomovar III CF-related strains. (Additional methodological details are at http://go.to/cepacia). Our finding in soil samples of a B cepacia genomovar III clone that causes extensive infection in patients with cystic fibrosis indicates that human pathogenic strains are not necessarily distinct from environmental strains, an issue central to the debate over commercial use of B cepacia complex species in agriculture and bioremediation. This finding also has important implications for infection control in patients with cystic fibrosis, which presently focuses on preventing interpatient spread of B cepacia complex. Acquisition of B cepacia complex from the natural environment might explain why current control measures have not eliminated the incidence of this infection in patients with cystic fibrosis. Further study is needed to define more specifically the preferred natural habitats of each B cepacia complex species. The risk posed by soil-borne strains and the optimal measures to mitigate this risk can then be determined. Contributors C F Gonzalez did the initial identification and characterisation of the soil isolates and the pehA gene analyses. T Coenye did the fliC RFLP analyses. T Spilker did the speciation, genotyping, and cluster analyses. J J LiPuma did the idenfication and genotyping analyses and wrote the paper. All investigators helped to write and revise the report.
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Breastfeeding might confer protection against obesity later in life, but the evidence is inconclusive. We tested the hypothesis that breastfeeding is associated with a reduced risk of obesity in a population-based sample of 32 200 Scottish children studied at age 39–42 months in 1998 and 1999. Obesity was defined as body-mass index (BMI) at the 95th and 98th percentiles or higher. The prevalence of obesity was significantly lower in breastfed children, and the association persisted after adjustment for socioeconomic status, birthweight, and sex. The adjusted odds ratio for obesity (BMI ⭓98th percentile) was 0·70 (95% CI 0·61–0·80). Our results suggest that breastfeeding is associated with a reduction in childhood obesity risk.
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Few strategies for prevention of childhood obesity are evidence based.1 Breastfeeding is one strategy that has many benefits, in addition to a possible protective effect on risk of obesity later in life. There are several probable mechanisms by which breastfeeding might protect against obesity, but evidence is inconclusive: most previous studies were limited by sample size and failure to control for confounding variables.2 In one study,3 the confounding effect of socioeconomic status was not adequately considered. The results of two other studies1 were also inconclusive, in part because of limited sample size. Our aim was to test the hypothesis that breastfeeding is associated with a reduced risk of obesity in young children in a populationbased, contemporary sample. We investigated a cohort of Scottish children born in 1995 or 1996, who were routinely reviewed by their health visitor at age 6–8 weeks as part of the Child Health Surveillance Programme. More than 98% of Scottish children attend these health reviews. At this review, the health visitor records whether the baby has been breastfed, fed on formula, or both. In our cohort, 25% of infants were fed only breastmilk, 7% were fed breastmilk and formula, and 68% were fed only formula. Children recorded as exclusively breastfed or exclusively fed on formula were included in the analysis, resulting in a total of 52 394 eligible children. This information was linked to the Child Health
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