Publications

The direct binding of bacteria to platelets is a central interaction in the pathogenesis of infective endocarditis. GspB is a serine-rich, cell wall glycoprotein of Streptococcus gordonii that mediates the binding of this organism to human platelets in vitro. To assess the contribution of this adhesin to the pathogenesis of endocarditis, we compared the virulence of S. gordonii M99 (which expresses GspB) with an isogenic, gspB mutant (PS846) in two rat models of endovascular infection. In the first group of experiments, animals were infected intravenously with M99 or PS846, and sacrificed 72 h later, to assess levels of bacteria within cardiac vegetations, kidneys, and spleens. When inoculated with 10(5)CFU, rats infected with PS846 had significantly lower densities of organisms within vegetations (mean: 3.84 log(10)CFU/g) as compared with M99-infected rats (6.67 log(10)CFU/g; P<0.001). Marked differences were also seen in rats co-infected with M99 and PS846, at a 1:1 ratio. While M99 was found at high levels within vegetations, kidneys and spleens (mean log(10)CFU/g: 6.62, 5.07 and 4.18, respectively) PS846 was not detected within these tissues. Thus, platelet binding by GspB appears to be a major interaction in the pathogenesis of endocarditis due to S. gordonii.

Genetic structure in the European American population reflects waves of migration and recent gene flow among different populations. This complex structure can introduce bias in genetic association studies. Using Principal Components Analysis (PCA), we analyze the structure of two independent European American datasets (1,521 individuals-307,315 autosomal SNPs). Individual variation lies across a continuum with some individuals showing high degrees of admixture with non-European populations, as demonstrated through joint analysis with HapMap data. The CEPH Europeans only represent a small fraction of the variation encountered in the larger European American datasets we studied. We interpret the first eigenvector of this data as correlated with ancestry, and we apply an algorithm that we have previously described to select PCA-informative markers (PCAIMs) that can reproduce this structure. Importantly, we develop a novel method that can remove redundancy from the selected SNP panels and show that we can effectively remove correlated markers, thus increasing genotyping savings. Only 150-200 PCAIMs suffice to accurately predict fine structure in European American datasets, as identified by PCA. Simulating association studies, we couple our method with a PCA-based stratification correction tool and demonstrate that a small number of PCAIMs can efficiently remove false correlations with almost no loss in power. The structure informative SNPs that we propose are an important resource for genetic association studies of European Americans. Furthermore, our redundancy removal algorithm can be applied on sets of ancestry informative markers selected with any method in order to select the most uncorrelated SNPs, and significantly decreases genotyping costs.

AIMS

Recent large association studies have revealed associations between genetic polymorphisms and myocardial infarction and coronary heart disease (CHD). We performed a replication study of 10 polymorphisms and CHD in a population with familial hypercholesterolemia (FH), individuals at extreme risk of CHD.

METHODS AND RESULTS

We genotyped 10 polymorphisms in 2145 FH patients and studied the association between these polymorphisms and CHD in Cox proportional hazards models. We confirmed the associations between four polymorphisms and CHD, the rs1151640 polymorphism in the olfactory receptor family 13 subfamily G member 1 (OR13G1) gene (HR 1.14, 95% CI 1.01-1.28, P = 0.03), the rs11881940 polymorphism in the heterogeneous nuclear ribonucleoprotein U-like 1 (HNRPUL1) gene (HR 1.27, 95% CI 1.07-1.51, P = 0.007), the rs3746731 polymorphism in the complement component 1 q subcomponent receptor 1 (CD93) gene (HR 1.26, 95% CI 1.06-1.49, P = 0.01), and the rs10757274 polymorphism near the cyclin-dependent kinase N2A and N2B (CDKN2A and CDKN2B) genes (HR 1.39, 95% CI 1.15-1.69, P < 0.001).

CONCLUSION

We confirmed previously found associations between four polymorphisms and CHD, but refuted associations for six other polymorphisms in our large FH population. These findings stress the importance of replication before genetic information can be implemented in the prediction of CHD.

PURPOSE

This study reports on prostate edema after prostate brachytherapy using Cesium-131 ((131)Cs) and describes our method to compensate.

METHODS AND MATERIALS

Thirty-one patients underwent brachytherapy using an afterloading technique. Volume measurements of the prostate were taken at various time intervals relative to the date of implant. Real-time operating room dosimetry was used for seed placement on the postneedle prostate volume. The prostate volumes at the various time points were used to determine the effect of prostate edema on dosimetry.

RESULTS

Increase in prostate volume occurred immediately after needle placement, as measured by both ultrasound (mean increase of 17.7% (0-75.0%) from 36.8 to 46.9 cc) and Day 0 CT (mean increase of 15.3% (0-54.8%) to 45.9 cc). Day 0 assessment of dosimetry revealed a median D(90) of 102.7% (86.7-133.4%), median V(100) of 91.8% (75.9-98.4%), median V(150) of 44.4% (23.8-81.3%), and median V(200) of 16.3% (7.8-36.9%). This edema dissipated over the next 4 weeks, with resultant changes in dosimetric parameters. By 4 weeks, prostate volume had returned to the preimplant volume (37.7 cc) with increased D(90) (118.2%), V(100) (95.6%), V(150) (63.9%), and V(200) (28.4%).

CONCLUSIONS

There is significant immediate edema with prostate brachytherapy. This affects the dosimetry of the implant substantially. Because of this edema, our planning for brachytherapy is done on the postneedle implant volume. Quality assurance studies should be done on the same day as the implant to avoid substantial overestimation of dosimetric parameters.

BACKGROUND

Fluorescent reporters are useful for assaying gene expression in living cells and for identifying and isolating pure cell populations from heterogeneous cultures, including embryonic stem (ES) cells. Multiple fluorophores and genetic selection markers exist; however, a system for creating reporter constructs that preserve the regulatory sequences near a gene's native ATG start site has not been widely available.

METHODOLOGY

Here, we describe a series of modular marker plasmids containing independent reporter, bacterial selection, and eukaryotic selection components, compatible with both Gateway recombination and lambda prophage bacterial artificial chromosome (BAC) recombineering techniques. A 2A self-cleaving peptide links the reporter to the native open reading frame. We use an emerald GFP marker cassette to create a human BAC reporter and ES cell reporter line for the early cardiac marker NKX2-5. NKX2-5 expression was detected in differentiating mouse ES cells and ES cell-derived mice.

CONCLUSIONS

Our results describe a NKX2-5 ES cell reporter line for studying early events in cardiomyocyte formation. The results also demonstrate that our modular marker plasmids could be used for generating reporters from unmodified BACs, potentially as part of an ES cell reporter library.

PURPOSE OF REVIEW

Evaluation and management of patients with pulmonary nodules continue to be a significant clinical challenge due to the possibility of malignancy.

RECENT FINDINGS

With advances in technology, several minimally invasive diagnostic options are available for diagnosis of peripheral pulmonary lesions. Development and refinement of minimally invasive sampling techniques will aid in clinical decision making, as well as help advance scientific understanding of lung cancer growth and metastasis.

SUMMARY

Although most surgical candidates should be referred promptly for resection, transthoracic or bronchoscopic biopsy may be particularly helpful when an infectious cause is suspected, when the patient is a marginal or poor candidate for surgery, or when a surgical candidate desires proof of malignancy before proceeding to surgery.Newer minimally invasive techniques should be rigorously evaluated for their role in the diagnostic algorithm of peripheral lung lesions.