Real-time detection of Brucella abortus, Brucella melitensis and Brucella suis

Real-time PCR-based assays specific for Brucella abortus, Brucella melitensis and Brucella suis were developed. The assays utilize an upstream primer that is derived from 3' end of the genetic element IS 711, whereas the downstream primers and probes are designed from signature sequences specific to a species or a biovar. The PCR reactions were monitored for fluorescence resonance energy transfer by including two adjacent labeled probes that hybridize to the amplicons as they are formed. The upstream probes were labeled with fluorescein at 3' end while Cy5 was attached to the 5' end of the downstream probes. An increase in the ratio of fluorescein to Cy5 fluorescence during the cycling was indicative of positive amplification event. The assays were accomplished in less than 30 min using a LightCycler in real-time mode. The assays were tested on known strains as well as field isolates and were found to be specific for all known biovars of B. abortus, B. melitensis and biovar 1 of B. suis. Therefore, specificity, sensitivity, speed and real-time detection make these assays attractive for use in epidemiological and ecological studies.

Identification of bacteria from a non-healing diabetic foot wound by 16 S rDNA sequencing

Approximately 10-20% of diabetic foot wounds fail initial antibiotic treatment. It is generally believed that several bacterial species may be present in these types of wounds. Because some of these organisms cannot be easily cultured, proper identification is problematic and thus, appropriate treatment modalities cannot be applied. This report examined the bacterial flora present in a chronic diabetic foot wound that failed antibiotic treatment. A tissue sample was collected from the base of the wound and used for standard microbiological culturing. DNA from the sample was used to amplify bacterial 16 S rDNA gene sequences and a library of these sequences was made. The clones were placed into two major groups on the basis of their melting temperatures. Representatives of these groups were sequenced, and information was used to identify the bacteria present in the wound. The culture-based method identified a single anaerobic species, Bacteroides fragilis. The method employing rDNA sequencing identified B. fragilis as a dominant organism and Pseudomonas (Janthinobacterium) mephitica as a minor component. The results indicate that rDNA sequencing approach can be an important tool in the identification of bacteria from wounds.

Accelerated atherosclerosis and premature calcified cartilaginous metaplasia in the aorta of diabetic male Apo E knockout mice can be prevented by chronic treatment with 17 beta-estradiol

Epidemiological data indicate that estrogens significantly reduce the risk of morbidity and mortality due to cardiovascular diseases in postmenopausal women. Although numerous animal studies demonstrated inhibition of early atheromatous lesion formation by estrogen treatment in several species, information about the potential benefits of estrogens on complex, advanced atherosclerotic lesions is still lacking. The present study was designed to test whether chronic treatment with 17 beta-estradiol affects hyperglycemia-induced premature advanced lesion formation in 40-week-old male apolipoprotein E-deficient (Apo E-KO) mice. In order to accelerate advanced lesion formation, we treated male Apo E-KO mice with streptozotocin (STZ) at the age of 6 weeks. Two weeks later the STZ-treated mice received a slow release pellet containing either 17 beta-estradiol or placebo. STZ treatment caused sustained hyperglycemia without changes in serum total cholesterol or triglyceride levels compared to citrate control mice. STZ-treated Apo E-KO mice developed significantly more lesions in some (but not all) parts of the aorta and its main branches, and caused premature calcified cartilaginous metaplasia in the lesions of the proximal aorta. Chronic treatment with 17 beta-estradiol lead to a significant decrease in blood glucose and triglyceride levels, reduced the lesion area in all vascular segments studied and prevented cartilaginous metaplasia in STZ-treated Apo E-KO mice. The results of this study show that STZ treatment leads to significant acceleration of atherosclerotic lesion formation and premature occurrence of calcified cartilaginous areas in Apo E-KO mice, which could be effectively prevented by chronic estrogen treatment.

Expression of interleukin-6 in atherosclerotic lesions of male ApoE-knockout mice: inhibition by 17beta-estradiol

Increased levels of interleukin-6 (IL-6) have been proposed to contribute to a number of pathological disorders, including osteoporosis and Alzheimer's disease. In human atherosclerotic lesions, IL-6 protein and mRNA have been detected, although the role of IL-6 in plaque formation is unknown. We have examined the expression pattern of IL-6 mRNA and secreted protein in male apolipoprotein E-knockout (apoE-KO) mice aortas. Furthermore, we have evaluated the effects of 17beta-estradiol (E2), a vasculoprotective sex steroid hormone, on the secretion of this inflammatory cytokine from isolated male apoE-KO mice aortas. The expression of IL-6 mRNA was detected by reverse transcription-polymerase chain reaction in the apoE-KO mouse aortas but not in the aortas of age-matched control mice. Similarly, the secretion of IL-6 protein from isolated apoE-KO aortic segments was significantly greater than that from aortas of age-matched control animals. The secretion of IL-6 from isolated aortic rings of apoE-KO mice ranging in age from 6 to 48 weeks showed a significant, positive correlation with percent lesion area measured in the same tissue. Immunohistochemical staining of apoE-KO mouse aortic tissue sections demonstrated colocalization of IL-6 expression with macrophages. Treatment of male apoE-KO mice with E2 for 3 weeks resulted in a statistically significant 50% reduction in IL-6 secretion from ex vivo aortic tissue segments. There was no significant change in total serum cholesterol and triglyceride levels in the E2-treated group compared with placebo-treated controls. These data demonstrate that (1) IL-6 mRNA and protein are expressed in the atherosclerotic plaques of apoE-KO mice aortas and (2) IL-6 production is suppressed by E2 treatment, which may contribute to the antiatherosclerotic effects of E2 in the apoE-KO mouse model of atherosclerosis.

CD4-independent association between HIV-1 gp120 and CXCR4: functional chemokine receptors are expressed in human neurons

BACKGROUND

Chemokines are a family of proteins that chemoattract and activate immune cells by interacting with specific receptors on the surface of their targets. We have shown previously that chemokine receptors including the interleukin-8 receptor B (CXCR2) and the Duffy blood group antigen are expressed on subsets of neurons in various regions of the adult nervous system.

RESULTS

Using a combination of immunohistochemical staining and receptor binding studies, we show that hNT cells, which are differentiated human neurons derived from the cell line NTera2, express functional chemokine receptors of the C-X-X and C-C types. These chemokine receptors include CXCR2, CXCR4, CCR1 and CCR5. We demonstrate high-affinity binding of both types of chemokines to hNT neurons and dose-dependent chemotactic responses to these chemokines in differentiated, but no t undifferentiated, NTera 2 cells. In addition, we show that the envelop glycoprotein from the T-cell-tropic human immunodeficiency virus 1 (HIV-1) strain IIIB is a CD4-independent, dose-dependent inhibitor of the binding of stromal cell-derived factor 1 to its receptor, CXCR4.

CONCLUSIONS

These data support recent findings that members of the chemokine family, including CCR5 and LESTR/Fusin (CXCR4), function as coreceptors in combination with CD4 for HIV-1 invasion. This is the first report of functional expression of chemokine receptors on human neurons. Furthermore, our studies provide for direct CD4-independent association of the viral envelope protein of the HIV-1 strain III with the chemokine receptor CXCR4.