Thrombus of the ascending aorta: a rare cause of myocardial infarction.

We present two cases of a thrombus in the ascending aorta causing an acute myocardial infarction (AMI) and review the 10 other cases previously reported in the literature. This life-threatening condition appears to be more common in female smokers in their fifth decade. Suspicion should be raised in individuals at low risk for atherosclerotic disease with coronary angiographic findings not in keeping with the clinical presentation. The diagnosis may be obtained by transesophageal echocardiography, and we generally recommend surgical thrombectomy.     

Perceived environment and physical activity in youth

The examination of physical environments to explain and promote physical activity is an important yet under-investigated area of research inquiry. This study explored relationships between the perceived availability of physical environmental resources and the perceived importance of these resources in relation to physical activity levels amongst youth. A self-report questionnaire was completed by 610 students (mean age = 15.5 years old; 62% female participants) from four high schools (grades 9-12) in rural Alberta, Canada. Perceived physical environment constructs explained 5% of the variance in physical activity, with home, neighborhood, and school as significant domains. Perceived importance constructs explained 8% of the variance in physical activity with school context showing the only significant relationship with physical activity. A hierarchical regression analysis entered sex, grade, self-efficacy, peer, family and physical education teacher relationships, as the first block and eight environmental constructs as the second block. The first block variables accounted for 22% of the variance and environmental constructs accounted for an added 4% of the variance in physical activity. Perceived importance of the school environment was the only environment variable significantly associated with physical activity (β = .14; p < .05) after taking into account the impact of these traditional predictors. These findings reinforce the need to provide and support school physical environments related to physical activity.     

Titanium particles identified by energy-dispersive X-ray microanalysis within the lungs of a painter at autopsy

A 72-year-old male painter, who complained of his "lungs burning" for 2 weeks, died suddenly. Autopsy examination revealed severe coronary atherosclerosis with plaque rupture as the cause of death. Examination of the lungs revealed emphysema, interstitial fibrosis, and multinucleated giant cells with intra- and extracellular brown-black, crystalline, polarizable foreign material. Energy-dispersive X-ray microanalysis showed the material to contain titanium, aluminum, silicon, and iron. An increased incidence of respiratory disease has been reported in professional painters. Titanium is widely used as a pigment in the manufacturing of commercial paints. Cases of pneumoconiosis and alveolar proteinosis have been described in painters in which analysis of lung tissue revealed increased levels of titanium. This case is presented as an example of a rarely reported phenomenon, which may have clinical implications for evaluation and management of lung disease in painters.     

Disruption of the gene homologous to mammalian Nramp1 in Mycobacterium tuberculosis does not affect virulence in mice

Natural-resistance-associated macrophage protein 1 (Nramp1) is a divalent cation transporter belonging to a family of transporter proteins highly conserved in eukaryotes and prokaryotes. Mammalian and bacterial transporters may compete for essential metal ions during mycobacterial infections. The mycobacterial Nramp homolog may therefore be involved in Mycobacterium tuberculosis virulence. Here, we investigated this possibility by inactivating the M. tuberculosis Nramp1 gene (Mramp) by allelic exchange mutagenesis. Disruption of Mramp did not affect the extracellular growth of bacteria under standard conditions. However, the Mramp mutation was associated with growth impairment under conditions of limited iron availability. The Mramp mutant displayed no impairment of growth or survival in macrophages derived from mouse bone marrow or in Nramp1(+/+) and Nramp1(-/-) congenic murine macrophage cell lines. Following intravenous challenge in BALB/c mice, counts of parental and Mramp mutant strains were similar in the lungs and spleens of the animals at all time points studied. These results indicate that Mramp does not contribute to the virulence of M. tuberculosis in mice.     

Inherited partial duplication of chromosome No. 15

A boy with unusual facial appearance and mental retardation was found to have duplication for the distal half of the long arm of chromosome No. 15 and possibly deficiency for the distal end of the long arm of No. 21. The chromosome abnormality was inherited from his mother, who had a translocation involving chromosomes Nos. 15 and 21. Giemsa-banding localized the break point in chromosome No. 15 just distal to the intense band at the midportion of the long arm. The break point in chromosome No. 21 appeared to be at the distal end of the long arm. The difficulty encountered in cytogenetic analysis of the propositus with conventional staining, the importance of chromosome analysis of the parents, and the application of differential staining techniques are also presented.     

In vitro studies with recombinant Plasmodium falciparum apical membrane antigen 1 (AMA1): production and activity of an AMA1 vaccine and generation of a multiallelic response

Apical membrane antigen 1 (AMA1) is regarded as a leading malaria blood-stage vaccine candidate. While the overall structure of AMA1 is conserved in Plasmodium spp., numerous AMA1 allelic variants of P. falciparum have been described. The effect of AMA1 allelic diversity on the ability of a recombinant AMA1 vaccine to protect against human infection by different P. falciparum strains is unknown. We characterize two allelic forms of AMA1 that were both produced in Pichia pastoris at a sufficient economy of scale to be usable for clinical vaccine studies. Both proteins were used to immunize rabbits, singly and in combination, in order to evaluate their immunogenicity and the ability of elicited antibodies to block the growth of different P. falciparum clones. Both antigens, when used alone, elicited high homologous anti-AMA1 titers, with reduced strain cross-reactivity. Similarly, sera from rabbits immunized with a single antigen were capable of blocking the growth of homologous parasite strains at levels theoretically sufficient to clear parasite infections. However, heterologous inhibition was significantly reduced, providing experimental evidence that AMA1 allelic diversity is a result of immune pressure. Encouragingly, rabbits immunized with a combination of both antigens exhibited titers and levels of parasite inhibition as good as those of the single-antigen-immunized rabbits for each of the homologous parasite lines, and consequently exhibited a broadening of allelic diversity coverage.     

Experimental infection of cattle of different ages with infectious bovine rhinotracheitis virus (Strichen strain)

The clinical signs and pathological lesions which developed in various ages of cattle experimentally infected intranasally with the "Strichen" strain of IBR virus were similar to, but generally milder than, those of the field disease. The clinical signs were most severe 4 days after infection and had almost wholly regressed after 12 days. Serum neutralizing antibodies were detected in every animal. Virus was isolated from nasal and ocular swabs for up to 13 days and 10 days, respectively, after infection. The clinical signs and the pathological lesions were more severe in the younger animals.     

Strain variation in tumor necrosis factor induction by parasites from children with acute falciparum malaria.

A small proportion of individuals infected with Plasmodium falciparum develop cerebral malaria. Why it affects some infected individuals but not others is poorly understood. Since tumor necrosis factor (TNF) has been implicated strongly in the pathogenesis of cerebral malaria, here we have compared different parasite isolates for their ability to induce TNF production by human mononuclear cells in vitro. Wild isolates were collected from 34 Gambian children with cerebral malaria and 66 children with uncomplicated malaria fever. Cerebral malaria isolates tended to stimulate more TNF production than mild malaria isolates, but there was considerable overlap between the two groups, and the present data provide only limited support for the hypothesis that cerebral malaria is caused by strains of P. falciparum inducing high levels of TNF. However, it is notable that the amounts of TNF induced by different wild isolates from a single locality differed by over 100-fold. The biological significance of this polymorphism deserves further scrutiny in view of the central role that TNF is believed to play in host defense and in the clinical symptomatology of human malaria.     

Impact of selenium status on the pathogenesis of mycobacterial disease in HIV-1-infected drug users during the era of highly active antiretroviral therapy

The risk of mycobacterial disease is significantly increased in drug abusers as well as in immunocompromised HIV-1-infected individuals. The essential trace element selenium has an important function in maintaining immune processes and may, thus, have a critical role in clearance of mycobacteria. The impact of selenium status on the development of mycobacterial diseases in HIV-1-seropositive drug users was investigated over a 2-year period (1999-2001). Twelve cases of mycobacterial disease (tuberculosis, 9; infection due to atypical Mycobacterium species, 3) occurred; these 12 cases were compared with 32 controls with no history of respiratory infections who were matched on age, sex, and HIV status. Significant risk for development of mycobacterial disease was associated with a CD4 cell count of <200/mm 3, malnutrition, and selenium levels of 相似文献