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Educating medical students about the identification of risk factors for coronary disease and hypertension should be enhanced by exercises in which medical students identify their own risk factors and visualize the impact of current risk status on future risk of disease. A cohort of 1,130 former Johns Hopkins medical students were examined in medical school and followed annually from 1948 to 1964 to identify youthful factors associated with the development of coronary heart disease and hypertension in midlife. In the ensuing years through 1984, 51 cases of coronary heart disease and 114 cases of hypertension developed. Multiple risk equations using Cox proportional hazards regression were developed to predict these endpoints. Incidence of coronary heart disease was predicted best by an equation containing age, serum cholesterol at baseline, cigarette smoking at baseline, and paternal history of coronary disease. Hypertension was predicted best by an equation containing age, systolic blood pressure at baseline, paternal history of hypertension, and Quetelet index. These equations were applied to a class of present-day medical students to demonstrate the considerable variability in 30-year risk of coronary disease or hypertension. Thus, coronary heart disease and hypertension in midlife can be predicted by factors identified in youth. The Johns Hopkins multiple risk equations may be valuable as tools in preventive cardiology education to illustrate risk assessment and the importance of risk factor interventions.

We conducted a prospective investigation of the effect of coffee consumption on coronary heart disease in 1130 male medical students who were followed for 19 to 35 years. Changes in coffee consumption and cigarette smoking during follow-up were examined in relation to the incidence of clinically evident coronary disease in comparisons of three measures of coffee intake--base-line intake, average intake, and most recent intake reported before the manifestation of coronary disease. Clinical evidence of coronary disease included myocardial infarction, angina, and sudden cardiac death. In separate analyses for each measure of coffee intake, the relative risks for men drinking five or more cups of coffee per day, as compared with nondrinkers, were approximately 2.80 for all three measures in the univariate analyses (maximum width of 95 percent confidence intervals, 1.27 to 6.51). After adjustment for age, current smoking, hypertension status, and base-line level of serum cholesterol, the estimated relative risk for men drinking five or more cups of coffee per day (using the most recent coffee intake measure), as compared with those drinking none, was 2.49 (maximum width of 95 percent confidence interval, 1.08 to 5.77). The association between coffee and coronary disease was strongest when the time between the reports of coffee intake and the coronary event was shortest. These findings support an independent, dose-responsive association of coffee consumption with clinically evident coronary heart disease, which is consistent with a twofold to threefold elevation in risk among heavy coffee drinkers.

OBJECTIVE: Adult hypertension is independently associated with elevated C-reactive protein levels, after controlling for obesity and other cardiovascular risk factors. The objective of this study was to determine, with a nationally representative sample of children, whether the relationship between elevated blood pressure and C-reactive protein levels may be evident before adulthood. METHODS: Cross-sectional data for children 8 to 17 years of age who participated in the National Health and Nutrition Examination Survey between 1999 and 2004 were analyzed. Bivariate analyses compared children with C-reactive protein levels of >3 mg/L versus or=95th percentile and 1.3% had diastolic blood pressure of >or=95th percentile. Children with C-reactive protein levels of >3 mg/L had higher systolic blood pressure, compared with children with C-reactive protein levels of or=95th percentile was independently associated with C-reactive protein levels in boys but not girls. Subset analyses according to race/ethnicity demonstrated that the independent association of elevated systolic blood pressure with C-reactive protein levels was largely limited to black boys. CONCLUSIONS: These data indicate that there is interplay between race/ethnicity, elevated systolic blood pressure, obesity, and inflammation in children, a finding that has potential implications for disparities in cardiovascular disease later in life. [ABSTRACT FROM AUTHOR]

BACKGROUND: In subjects with a high prevalence of metabolic risk abnormalities, the preferred replacement for saturated fat is unresolved. OBJECTIVE: The objective was to study whether carbohydrate or monounsaturated fat is a preferred replacement for saturated fat. DESIGN: Fifty-two men and 33 women, selected to have any combination of HDL cholesterol < or = 30th percentile, triacylglycerol > or = 70th percentile, or insulin > or = 70th percentile, were enrolled in a 3-period, 7-wk randomized crossover study. The subjects consumed an average American diet (AAD; 36% of energy from fat) and 2 additional diets in which 7% of energy from saturated fat was replaced with either carbohydrate (CHO diet) or monounsaturated fatty acids (MUFA diet). RESULTS: Relative to the AAD, LDL cholesterol was lower with both the CHO (-7.0%) and MUFA (-6.3%) diets, whereas the difference in HDL cholesterol was smaller during the MUFA diet (-4.3%) than during the CHO diet (-7.2%). Plasma triacylglycerols tended to be lower with the MUFA diet, but were significantly higher with the CHO diet. Although dietary lipid responses varied on the basis of baseline lipid profiles, the response to diet did not differ between subjects with or without the metabolic syndrome or with or without insulin resistance. Postprandial triacylglycerol concentrations did not differ significantly between the diets. Lipoprotein(a) concentrations increased with both the CHO (20%) and MUFA (11%) diets relative to the AAD. CONCLUSIONS: In the study population, who were at increased risk of coronary artery disease, MUFA provided a greater reduction in risk as a replacement for saturated fat than did carbohydrate. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To examine whether the improvements in lipid profiles and low-density lipoprotein cholesterol (LDL-C) goal attainment found in the Ezetimibe Add-On to Statin for Effectiveness trial occurred equally in the black, Hispanic, and white patient populations enrolled in the study. PATIENTS AND METHODS: In this double-blind, placebo-controlled study, patients were recruited from 299 community-based practices across the United States (January to August 2003). Patients with, hypercholesterolemia and LDL-C levels exceeding National Cholesterol Education Program Adult Treatment Panel III goals were randomized (2:1) to receive either ezetimibe (10 mg/d) or placebo in addition to their ongoing statin therapy for 6 weeks. RESULTS: A total of 5802 patients were screened at baseline for the Ezetimibe Add-On to Statin for Effectiveness study. Of these, 2772 were excluded, and the remaining 3030 eligible patients were randomized. Ezetimibe, compared with placebo, added to statin therapy significantly reduced LDL-C levels from statin-treated baseline by 23.0% (white patients), 23.0% (black patients), and 21.0% (Hispanic patients). This effect was consistent across race and ethnicity groups (P > .50 for treatment-by-race interactions). Ezetimibe added to statin therapy also statistically significantly (P < .001) increased the percentage of patients attaining their LDL-C goal for their National Cholesterol Education Program Adult Treatment Panel III risk category in black (63.0%), Hispanic (64.8%), and white (72.3%) patients compared with placebo plus statin (32.9% black patients, 19.0% Hispanic patients, and 19.7% white patients). Ezetimibe treatment improved other lipid parameters across groups, including triglyceride, high-density lipoprotein cholesterol, non-high-density ilpoprotein cholesterol, and total cholesterol levels. Finally, the addition of ezetimibe reduced high-sensitivity C-reactive protein levels overall, and no significant interaction of treatment by race occurred (P = .83), Indicating a consistent effect across races. Ezetimibe was generally well tolerated, and no detectable differences occurred in the adverse event profile by race or ethnicity. CONCLUSION: Ezetimibe added to statin therapy is effective and well tolerated for improving the lipid profile and LDL-C goal attainment of patients regardless of race or ethnicity. [ABSTRACT FROM AUTHOR]

OBJECTIVE: To determine the extent of reduction in low-density lipoprotein cholesterol (LDL-C) level and improvement in National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III) LDL-C goal attainment when ezetimibe was added to ongoing statin therapy in a diverse population of community-based patients. PATIENTS AND METHODS: In this multicenter, double-blind, placebo-controlled trial (from January 2003 to August 2003), hypercholesterolemic patients (from 299 US primary care and specialty practices) with LDL-C levels exceeding NCEP ATP III goals were randomized (2:1) to receive ezetimibe (10 mg/d) or placebo in addition to their ongoing statin therapy for 6 weeks. RESULTS: In a study of 3030 randomized patients, ezetimibe added to statin therapy significantly reduced the LDL-C level by an additional 25.8% in the total population, compared with an additional 2.7% reduction with placebo plus statin (treatment difference, -23.1%; P<.001); the treatment difference ranged from -19.9% to -24.0% (P<.001) in each NCEP ATP III risk category subgroup. Significantly (P<.001) more patients (71.0%) treated with ezetimibe added to statin reached their NCEP ATP III target LDL-C level compared with those treated with placebo plus statin (20.6%). The addition of ezetimibe also resulted in improvement in other lipid parameters and high-sensitivity C-reactive protein levels. These benefits were consistent across sex, race, age, statin brand, and dose subgroups. Ezetimibe plus statin therapy was well tolerated, with a safety profile similar to placebo plus statin. CONCLUSION: Across multiple subgroups, ezetimibe added to statin therapy consistently produced significant additional improvements in LDL-C levels and goal attainment, as well as in other lipoproteins, compared with addition of placebo. The addition of ezetimibe to statin therapy should be considered for patients not achieving their NCEP ATP III LDL-C goals while receiving statin therapy alone. [ABSTRACT FROM AUTHOR]

Objectives: This study was designed to assess prospectively changes in serum lipid profile and myocardial perfusion with serial radionuclide single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) during the first six months of pravastatin therapy.Background: Morbid coronary events occur despite statin therapy and lipid-lowering in patients with coronary artery disease (CAD). A reliable strategy to identify responders with effective treatment from nonresponders on statin therapy before clinical events is needed.Methods: Rest and stress SPECT MPI and lipids were assessed serially in 25 patients (36% women) with CAD and dyslipidemia during the first six months of pravastatin therapy.Results: Total cholesterol, low-density lipoprotein cholesterol, and triglycerides declined (26%, 32%, and 30%, respectively) by six weeks and remained reduced at six months. Mean stress perfusion defect (summed stress score [SSS]) was severe (13.3 +/- 6.0) at baseline, showed no change at six weeks, and improved significantly at six months (10.3 +/- 7.3, p < 0.01). The six-month study SSS improved in 11 (48%) patients, was unchanged in 10 (43%) patients, and worsened in 2 (9%) patients. Changes in lipid levels did not reliably predict changes in myocardial perfusion at six weeks or six months in this small pilot study.Conclusions: Serial SPECT MPI demonstrated improved stress myocardial perfusion in 48% of patients treated for six months with pravastatin. Time course of improved myocardial perfusion during pravastatin therapy is delayed compared to lipids. Direction and magnitude of changes in the myocardial perfusion vary and do not correlate closely with improvements in lipids. [ABSTRACT FROM AUTHOR]

For the past 40 y the scientific community has decried the inadequacy of the training of physicians and other health professionals in the subject of human nutrition. In 1997 the National Heart, Lung, and Blood Institute developed the Nutrition Academic Award (NAA) Program, an initiative to improve nutrition training across a network of US medical schools. The purpose of this funding, which began in 1998, is to support the development and enhancement of nutrition curricula for medical students, residents, and practicing physicians to learn principles and practice skills in nutrition. The NAA recipients developed the Nutrition Curricular Guide for Training Physicians, a plan to incorporate clinical guidelines into physician practice skills, create educational and assessment practice tools, and evaluate curricula, materials, and teaching tools. Dissemination of NAA activities and materials will be facilitated by a national website, presentations and publications, and consultants and advisors from the NAA nutrition education programs. The NAA Program constitutes a major new effort to enhance nutrition knowledge and skills among health care providers and to effectively apply the science of human nutrition to clinical medicine. This article describes the purpose and aims of the NAA Program, the organizational structure of the network of recipients, a profile of the recipients and individual programs at 21 medical schools, the various strategies to overcome barriers in training physicians in human nutrition, and collaborative and dissemination efforts. Copyright © 2001 American Society for Clinical Nutrition [ABSTRACT FROM AUTHOR]

OBJECTIVES: To describe a rural, hospital-based public health intervention program and to evaluate its effectiveness in cardiovascular disease (CVD) risk reduction using cross-sectional studies and a panel study. METHODS: A rural population of 158,000 located in New York state comprised the intervention population. A similar but separate population was used for reference. A multifaceted, multimedia 5-year program provided health promotion and education initiatives to increase physical activity, decrease smoking, improve nutrition, and identify hypercholesterolemia and hypertension. To evaluate the effectiveness of the intervention, surveys were conducted at baseline in 1989 (cross-sectional) and at follow-up in 1994-95 (cross-sectional and panel). For cross-sectional studies, a random sample of adults was obtained using a three-stage cluster design. Self-reported and objective risk factor measurements were obtained. Comparison of pre- to post- changes in intervention versus reference populations was done using 2 x 2 randomized block ANOVA, 2 x 2 mixed ANOVA. and extension of the McNemar test. RESULTS: Smoking prevalence declined (from 27.9% to 17.6%) in the intervention population. Significant adverse trends were observed for high-density lipoprotein cholesterol and triglycerides. Systolic blood pressure was reduced while diastolic blood pressure remained stable. Body mass index increased significantly in both populations. CONCLUSIONS: This rural. 5-year CVD community intervention program decreased smoking. The risk reduction may be attributable to tailoring of a multifaceted approach (multiple risk factors, multiple messages, and multiple population subgroups) to a target rural population. The study period was too short to identify changes in CVD morbidity and mortality. [ABSTRACT FROM AUTHOR]

OBJECTIVES: There is a need among healthcare providers to acquire more knowledge about small-scale and low budget community intervention programmes. This paper compares risk factor outcomes in Swedish and US intervention programmes for the prevention of cardiovascular disease (CVD). The aim was to explore how different intervention programme profiles affect outcome. METHODS: Using a quasi-experimental design, trends in risk factors and estimated CVD risk in two intervention areas (Norsjo. Sweden and Otsego-Schoharie County, New York state) are compared with those in reference areas (Northern Sweden region and Herkimer County, New York state) using serial cross-sectional studies and panel studies. RESULTS: The programmes were able to achieve significant changes in CVD risk factors that the local communities recognized as major concerns: changing eating habits in the Swedish population and reducing smoking in the US population. For the Swedish cross-sectional follow-up study cholesterol reduction was 12%, compared to 5% in the reference population (p for trend differences <0.000). The significantly higher estimated CVD risk (as assessed by risk scores) at baseline in the intervention population was below that of the Swedish reference population after 5 years of intervention. The Swedish panel study provided the same results. In the US, both the serial cross-sectional and panel studies showed a > 10% decline in smoking prevalence in the intervention population, while it increased slightly in the reference population. When pooling the serial cross-sectional studies the estimated risk reduction (using the Framingham risk equation) was significantly greater in the intervention populations compared to the reference populations. CONCLUSIONS: The overall pattern of risk reduction is consistent and suggests that the two different models of rural county intervention can contribute to significant risk reduction. The Swedish programme had its greatest effect on reduction of serum cholesterol levels whereas the US programme had its greatest effect on smoking prevention and cessation. These outcomes are consistent with programmatic emphases. Socially less privileged groups in these rural areas benefited as much or more from the interventions as those with greater social resources. [ABSTRACT FROM AUTHOR]

OBJECTIVES: This paper aims to develop and describe a method for combining. comparing, and maximizing the statistical power of two longitudinal studies of risk factors for cardiovascular disease that did not have identical data collection methodologies. METHODS: Subjects from a 1986 cross-sectional study (n = 180) were pair-matched with subjects of corresponding gender and age (+5 years) from a 1990 cross-sectional study. The methodology is described and results are calculated for various measures of cardiovascular risk or risk factors (e.g. cholesterol. Finnish Risk Score). RESULTS: Box's test of equality and symmetry of covariance matrices gave chi-square values of 223.8 and 710.0 for two cardiovascular risk factors (cholesterol and cardiac risk score, respectively); these values were highly significant (p=0.0001) For the North Karelia Risk Score, repeated measures ANOVA revealed a borderline significant interaction for treatment by time (p=0.054) and a significant interaction for treatment by time by country (p=0.035). These probabilities compared favorably with a randomized blocks model. CONCLUSIONS: Creation of a synthetic longitudinal control group resulted in a statistically valid ANOVA model that increased the statistical power of the study. [ABSTRACT FROM AUTHOR]

With the antioxidant hypothesis gaining acceptance and the epidemiologic evidence impressive, the mixed results of clinical trials came as a surprise. Watch for more studies and additional interpretations of existing results. [ABSTRACT FROM AUTHOR]

Background: Low-fat diets increase plasma triacylglycerol and decrease HDL-cholesterol concentrations, thereby potentially adversely affecting cardiovascular disease (CVD) risk. High-monounsaturated fatty acid (MUFA), cholesterol-lowering diets do not raise triacylglycerol or lower HDL cholesterol, but little is known about how peanut products, a rich source of MUFAs, affect CVD risk. Objective: The present study compared the CVD risk profile of an Average American diet (AAD) with those of 4 cholesterol-lowering diets: an American Heart Association/National Cholesterol Education Program Step II diet and 3 high-MUFA diets [olive oil (OO), peanut oil (PO), and peanuts and peanut butter (PPB)]. Design: A randomized, double-blind, 5-period crossover study design (n = 22) was used to examine the effects of the diets on serum lipids and lipoproteins: AAD [34% fat; 16% saturated fatty acids (SFAs), 11% MUFAs], Step II (25% fat; 7% SFAs> 12% MUFAs), 00 (34% fat; 7% SFAs, 21 % MUFAs), PO (34% fat; 7% SFAs, 17% MUFAs), and PPB (36% fat; 8% SFAs, 18% MUFAs). Results: The high-MUFA diets lowered total cholesterol by 10% and LDL cholesterol by 14%. This response was comparable with that observed for the Step II diet. Triacylglycerol concentrations were 13% lower in subjects consuming the high-MUFA diets and were 11% higher with the Step II diet than with the AAD. The high-MUFA diets did not lower HDL cholesterol whereas the Step II diet lowered it by 4% compared with the AAD. The OO, PO, and PPB diets decreased CVD risk by an estimated 25%, 16%, and 21%, respectively, whereas the Step II diet lowered CVD risk by 12%. Conclusion: A high-MUFA, cholesterol-lowering diet may be preferable to a low-fat diet because of more favorable effects on the CVD risk profile. Copyright (c) 1999 American Society for Clinical Nutrition [ABSTRACT FROM AUTHOR]

Many hypercholesterolemic patients -- not just those with a history of heart disease -- may benefit from the cholesterol-lowering statins. But older drugs still have crucial roles. And, most important, so does diet. [ABSTRACT FROM AUTHOR]

Abstract Background Brucellosis is a worldwide disease of mammals caused by Alphaproteobacteria in the genus Brucella. The genus is genetically monomorphic, requiring extensive genotyping to differentiate isolates. We utilized two different genotyping strategies to characterize isolates. First, we developed a microarray-based assay based on 1000 single nucleotide polymorphisms (SNPs) that were identified from whole genome comparisons of two B. abortus isolates , one B. melitensis, and one B. suis. We then genotyped a diverse collection of 85 Brucella strains at these SNP loci and generated a phylogenetic tree of relationships. Second, we developed a selective primer-extension assay system using capillary electrophoresis that targeted 17 high value SNPs across 8 major branches of the phylogeny and determined their genotypes in a large collection ( n = 340) of diverse isolates. Results Our 1000 SNP microarray readily distinguished B. abortus, B. melitensis, and B. suis, differentiating B. melitensis and B. suis into two clades each. Brucella abortus was divided into four major clades. Our capillary-based SNP genotyping confirmed all major branches from the microarray assay and assigned all samples to defined lineages. Isolates from these lineages and closely related isolates, among the most commonly encountered lineages worldwide, can now be quickly and easily identified and genetically characterized. Conclusions We have identified clade-specific SNPs in Brucella that can be used for rapid assignment into major groups below the species level in the three main Brucella species. Our assays represent SNP genotyping approaches that can reliably determine the evolutionary relationships of bacterial isolates without the need for whole genome sequencing of all isolates.

Abstract Background An isolate originally labeled Bacillus megaterium CDC 684 was found to contain both pXO1 and pXO2, was non-hemolytic, sensitive to gamma-phage, and produced both the protective antigen and the poly-D-glutamic acid capsule. These phenotypes prompted Ezzell et al., (J. Clin. Microbiol. 28:223) to reclassify this isolate to Bacillus anthracis in 1990. Results We demonstrate that despite these B. anthracis features, the isolate is severely attenuated in a guinea pig model. This prompted whole genome sequencing and closure. The comparative analysis of CDC 684 to other sequenced B. anthracis isolates and further analysis reveals: a) CDC 684 is a close relative of a virulent strain, Vollum A0488; b) CDC 684 defines a new B. anthracis lineage (at least 51 SNPs) that includes 15 other isolates; c) the genome of CDC 684 contains a large chromosomal inversion that spans 3.3 Mbp; d) this inversion has caused a displacement of the usual spatial orientation of the origin of replication (ori) to the termination of replication (ter) from 180° in wild-type B. anthracis to 120° in CDC 684 and e) this isolate also has altered growth kinetics in liquid media. Conclusions We propose two alternative hypotheses explaining the attenuated phenotype of this isolate. Hypothesis 1 suggests that the skewed ori/ter relationship in CDC 684 has altered its DNA replication and/or transcriptome processes resulting in altered growth kinetics and virulence capacity. Hypothesis 2 suggests that one or more of the single nucleotide polymorphisms in CDC 684 has altered the expression of a regulatory element or other genes necessary for virulence.

Abstract Background Francisella tularensis, the causative agent of tularemia, displays subspecies-specific differences in virulence, geographic distribution, and genetic diversity. F. tularensis subsp. holarctica is widely distributed throughout the Northern Hemisphere. In Europe, F. tularensis subsp. holarctica isolates have largely been assigned to two phylogenetic groups that have specific geographic distributions. Most isolates from Western Europe are assigned to the B.Br.FTNF002-00 group, whereas most isolates from Eastern Europe are assigned to numerous lineages within the B.Br.013 group. The eastern geographic extent of the B.Br.013 group is currently unknown due to a lack of phylogenetic knowledge about populations at the European/Asian juncture and in Asia. In this study, we address this knowledge gap by describing the phylogenetic structure of F. tularensis subsp. holarctica isolates from the country of Georgia, and by placing these isolates into a global phylogeographic context. Results We identified a new genetic lineage of F. tularensis subsp. holarctica from Georgia that belongs to the B.Br.013 group. This new lineage is genetically and geographically distinct from lineages previously described from the B.Br.013 group from Central-Eastern Europe. Importantly, this new lineage is basal within the B.Br.013 group, indicating the Georgian lineage diverged before the diversification of the other known B.Br.013 lineages. Although two isolates from the Georgian lineage were collected nearby in the Ukrainian region of Crimea, all other global isolates assigned to this lineage were collected in Georgia. This restricted geographic distribution, as well as the high levels of genetic diversity within the lineage, is consistent with a relatively older origin and localized differentiation. Conclusions We identified a new lineage of F. tularensis subsp. holarctica from Georgia that appears to have an older origin than any other diversified lineages previously described from the B.Br.013 group. This finding suggests that additional phylogenetic studies of F. tularensis subsp. holarctica populations in Eastern Europe and Asia have the potential to yield important new insights into the evolutionary history and phylogeography of this broadly dispersed F. tularensis subspecies.

Abstract Background Phylogeographic reconstruction of some bacterial populations is hindered by low diversity coupled with high levels of lateral gene transfer. A comparison of recombination levels and diversity at seven housekeeping genes for eleven bacterial species, most of which are commonly cited as having high levels of lateral gene transfer shows that the relative contributions of homologous recombination versus mutation for Burkholderia pseudomallei is over two times higher than for Streptococcus pneumoniae and is thus the highest value yet reported in bacteria. Despite the potential for homologous recombination to increase diversity, B. pseudomallei exhibits a relative lack of diversity at these loci. In these situations, whole genome genotyping of orthologous shared single nucleotide polymorphism loci, discovered using next generation sequencing technologies, can provide very large data sets capable of estimating core phylogenetic relationships. We compared and searched 43 whole genome sequences of B. pseudomallei and its closest relatives for single nucleotide polymorphisms in orthologous shared regions to use in phylogenetic reconstruction. Results Bayesian phylogenetic analyses of >14,000 single nucleotide polymorphisms yielded completely resolved trees for these 43 strains with high levels of statistical support. These results enable a better understanding of a separate analysis of population differentiation among >1,700 B. pseudomallei isolates as defined by sequence data from seven housekeeping genes. We analyzed this larger data set for population structure and allele sharing that can be attributed to lateral gene transfer. Our results suggest that despite an almost panmictic population, we can detect two distinct populations of B. pseudomallei that conform to biogeographic patterns found in many plant and animal species. That is, separation along Wallace's Line, a biogeographic boundary between Southeast Asia and Australia. Conclusion We describe an Australian origin for B. pseudomallei, characterized by a single introduction event into Southeast Asia during a recent glacial period, and variable levels of lateral gene transfer within populations. These patterns provide insights into mechanisms of genetic diversification in B. pseudomallei and its closest relatives, and provide a framework for integrating the traditionally separate fields of population genetics and phylogenetics for other bacterial species with high levels of lateral gene transfer.

Abstract Background The global pattern of distribution of 1033 B. anthracis isolates has previously been defined by a set of 12 conserved canonical single nucleotide polymorphisms (canSNP). These studies reinforced the presence of three major lineages and 12 sub-lineages and sub-groups of this anthrax-causing pathogen. Isolates that form the A lineage (unlike the B and C lineages) have become widely dispersed throughout the world and form the basis for the geographical disposition of "modern" anthrax. An archival collection of 191 different B. anthracis isolates from China provides a glimpse into the possible role of Chinese trade and commerce in the spread of certain sub-lineages of this pathogen. Canonical single nucleotide polymorphism (canSNP) and multiple locus VNTR analysis (MLVA) typing has been used to examine this archival collection of isolates. Results The canSNP study indicates that there are 5 different sub-lineages/sub-groups in China out of 12 previously described world-wide canSNP genotypes. Three of these canSNP genotypes were only found in the western-most province of China, Xinjiang. These genotypes were A.Br.008/009, a sub-group that is spread across most of Europe and Asia; A.Br.Aust 94, a sub-lineage that is present in Europe and India, and A.Br.Vollum, a lineage that is also present in Europe. The remaining two canSNP genotypes are spread across the whole of China and belong to sub-group A.Br.001/002 and the A.Br.Ames sub-lineage, two closely related genotypes. MLVA typing adds resolution to the isolates in each canSNP genotype and diversity indices for the A.Br.008/009 and A.Br.001/002 sub-groups suggest that these represent older and established clades in China. Conclusion B. anthracis isolates were recovered from three canSNP sub-groups (A.Br.008/009, A.Br.Aust94, and A.Br.Vollum) in the western most portion of the large Chinese province of Xinjiang. The city of Kashi in this province appears to have served as a crossroads for not only trade but the movement of diseases such as anthrax along the ancient "silk road". Phylogenetic inference also suggests that the A.Br.Ames sub-lineage, first identified in the original Ames strain isolated from Jim Hogg County, TX, is descended from the A.Br.001/002 sub-group that has a major presence in most of China. These results suggest a genetic discontinuity between the younger Ames sub-lineage in Texas and the large Western North American sub-lineage spread across central Canada and the Dakotas.

Abstract Background The facultative, intracellular bacterium Burkholderia pseudomallei is the causative agent of melioidosis, a serious infectious disease of humans and animals. We identified and categorized tandem repeat arrays and their distribution throughout the genome of B. pseudomallei strain K96243 in order to develop a genetic typing method for B. pseudomallei. We then screened 104 of the potentially polymorphic loci across a diverse panel of 31 isolates including B. pseudomallei, B. mallei and B. thailandensis in order to identify loci with varying degrees of polymorphism. A subset of these tandem repeat arrays were subsequently developed into a multiple-locus VNTR analysis to examine 66 B. pseudomallei and 21 B. mallei isolates from around the world, as well as 95 lineages from a serial transfer experiment encompassing ~18,000 generations. Results B. pseudomallei contains a preponderance of tandem repeat loci throughout its genome, many of which are duplicated elsewhere in the genome. The majority of these loci are composed of repeat motif lengths of 6 to 9 bp with 4 to 10 repeat units and are predominately located in intergenic regions of the genome. Across geographically diverse B. pseudomallei and B.mallei isolates, the 32 VNTR loci displayed between 7 and 28 alleles, with Nei's diversity values ranging from 0.47 and 0.94. Mutation rates for these loci are comparable (>10-5 per locus per generation) to that of the most diverse tandemly repeated regions found in other less diverse bacteria. Conclusion The frequency, location and duplicate nature of tandemly repeated regions within the B. pseudomallei genome indicate that these tandem repeat regions may play a role in generating and maintaining adaptive genomic variation. Multiple-locus VNTR analysis revealed extensive diversity within the global isolate set containing B. pseudomallei and B. mallei, and it detected genotypic differences within clonal lineages of both species that were identical using previous typing methods. Given the health threat to humans and livestock and the potential for B. pseudomallei to be released intentionally, MLVA could prove to be an important tool for fine-scale epidemiological or forensic tracking of this increasingly important environmental pathogen.