A histomorphological study in age related changes in the elastic fiber system of the basilar artery

The aim of the study was to quantify the distribution of elastic fibers within the wall of the basilar artery. Three age groups were studied: 1) 0-1 yr.; 2) 20-50 yr. 3) > 50 yr. A histomorphometrical study was undertaken using an estimation of the linear density of the components of the fibrous elastic tissue system: the full length in the proximal and distal segments of the basilar artery was evaluated. Our results showed that: The elastic tissue of the basilar artery is not evenly distributed throughout the tunica media. Compared to the 0 to 1-year age group, mature elastic, elauninic and oxytalan fibers decreased with age. In all age groups the linear density of the mature elastic fibers was more evident in the proximal than in the distal segment of the artery.     

Contrast media-enhanced magnetic resonance imaging visualizes myocardial changes in the course of viral myocarditis

BACKGROUND: The course of tissue changes in acute myocarditis in humans is not well understood. Diagnostic tools currently available are unsatisfactory. We tested the hypothesis that inflammation is reflected by signal changes in contrast-enhanced magnetic resonance imaging (MRI). METHODS AND RESULTS: We assessed 44 consecutive patients with symptoms of acute myocarditis. Nineteen patients met the inclusion criteria revealing ECG changes, reduced myocardial function, elevated creatine kinase, positive troponin T, serological evidence for acute viral infection, exclusion of coronary heart disease, and positive antimyosin scintigraphy. We studied these patients on days 2, 7, 14, 28, and 84 after the onset of symptoms. We obtained ECG-triggered, T1-weighted images before and after application of 0.1 mmol/kg gadolinium. We measured the global relative signal enhancement of the left ventricular myocardium related to skeletal muscle and compared it with measurements in 18 volunteers. The global relative enhancement was higher in patients on days 2 (4.8+/-0.3 [mean+/-SE] versus 2.5+/-0.2; P<.0001); 7 (4.7+/-0.5, P<.0001); 14 (4.6+/-0.5, P<.0002); and 28 (3.9+/-0.4, P=.009) but not on day 84 (3.1+/-0.3; P=NS). On day 2, the enhancement was focal, whereas at later time points, the enhancement was diffuse. In patients with evidence of ongoing disease, the values remained elevated. CONCLUSIONS: Acute myocarditis evolves from a focal to a disseminated process during the first 2 weeks after onset of symptoms. Contrast media-enhanced MRI visualizes the localization, activity, and extent of inflammation and may serve as a powerful noninvasive diagnostic tool in acute myocarditis.     

Quorum sensing in Escherichia coli and Salmonella typhimurium

Escherichia coli and Salmonella typhimurium strains grown in Luria-Bertani medium containing glucose secrete a small soluble heat labile organic molecule that is involved in intercellular communication. The factor is not produced when the strains are grown in Luria-Bertani medium in the absence of glucose. Maximal secretion of the substance occurs in midexponential phase, and the extracellular activity is degraded as the glucose is depleted from the medium or by the onset of stationary phase. Destruction of the signaling molecule in stationary phase indicates that, in contrast to other quorum-sensing systems, quorum sensing in E. coli and S. typhimurium is critical for regulating behavior in the prestationary phase of growth. Our results further suggest that the signaling factor produced by E. coli and S. typhimurium is used to communicate both the cell density and the metabolic potential of the environment. Several laboratory and clinical strains of E. coli and S. typhimurium were screened for production of the signaling molecule, and most strains make it under conditions similar to those shown here for E. coli AB1157 and S. typhimurium LT2. However, we also show that E. coli strain DH5alpha does not make the soluble factor, indicating that this highly domesticated strain has lost the gene(s) or biosynthetic machinery necessary to produce the signaling substance. Implications for the involvement of quorum sensing in pathogenesis are discussed.     

Improved mimicry of a foot-and-mouth disease virus antigenic site by a viral peptide displayed on beta-galactosidase surface

A major antigenic site (site A) of foot-and-mouth disease virus includes multiple overlapping epitopes located within the flexible G-H loop of capsid protein VP1. We have studied the antigenicity of several recombinant E. coli beta-galactosidases displaying the site A from a serotype C virus in different surface regions of the bacterial enzyme. In each one of the explored insertion sites, the recombinant peptide shows different specificity with a set of anti-virus monoclonal antibodies directed to site A. In some of them, the inserted stretch mimics better than free or haemocyanin-coupled peptide the antigenicity of site A in the intact virus. In particular, an insertion within an exposed loop involved in the activating interface of beta-galactosidase (amino acids 272 to 287) led to a significant improvement of the overall reactivity. Since insertions at this site renders proteins enzymatically active, the activating interface could be an adequate place for the presentation of foreign antigens in correctly assembled beta-galactosidase tetramers. These results also suggest that anti-virus antibodies directed against the major antigenic site of FMDV recognize different conformations of the G-H loop, which are better reproduced in some of the recombinant proteins because of the dissimilar restrictions imposed by each particular insertion site.     

Comparative evaluation of National Committee for Clinical Laboratory Standards broth macrodilution and agar dilution screening methods for testing fluconazole susceptibility of Cryptococcus neoformans

A simple screening method for fluconazole susceptibility of Cryptococcus neoformans using 2% dextrose Sabouraud dextrose agar (SabDex) with fluconazole was compared to the National Committee for Clinical Laboratory Standards (NCCLS) broth macrodilution method. By this method, fluconazole-susceptible C. neoformans isolates are significantly smaller on medium with fluconazole than on fluconazole-free medium. Isolates with decreased susceptibility have normal-size colonies on medium containing fluconazole. The 48-h NCCLS broth macrodilution MICs (NCCLS MICs) for isolates with normal-size colonies on 8- or 16-microg/ml fluconazole plates were predicted to be > or =8 or > or =16 microg/ml, respectively. On medium with 16 microg of fluconazole per ml, all strains (84 of 84) for which the NCCLS MICs were <16 microg/ml were correctly predicted, as were all isolates (7 of 7) for which the MICs were > or =16 microg/ml. Agar dilution appears to be an effective screening method for fluconazole resistance in C. neoformans.     

Comparison of Etest and National Committee for Clinical Laboratory Standards broth macrodilution method for azole antifungal susceptibility testing

The use of Etest strips for antimicrobial susceptibility testing is a new and promising method with broad applications in microbiology. Since these strips contain a predefined continuous gradient of a drug, it is possible to obtain a reproducible, quantitative MIC reading. We performed a prospective and double-blinded study to compare the Etest and National Committee for Clinical Laboratory Standards (Villanova, Pa.) broth macrodilution methods for determining the MICs of fluconazole, itraconazole, and ketoconazole for 100 clinical isolates (25 Candida albicans, 25 Cryptococcus neoformans var. neoformans, 20 Torulopsis [Candida] glabrata, 15 Candida tropicalis, and 15 Candida parapsilosis). The Etest method was performed according to the manufacturer's instructions, and the reference method was performed according to National Committee for Clinical Laboratory Standards document M27-P guidelines. Despite differences between results for some species-drug combinations, Etest and macrobroth MICs were, in general, in good agreement. The MIC agreement rates for the two methods, within +/- 1 dilution, were 71% for ketoconazole, 80% for fluconazole, and 84% for itraconazole. According to our data, Etest has potential utility as an alternative method.     

p53 expression, DNA content and cell proliferation in primary and synchronous metastatic lesions from ovarian surface epithelial-stromal tumours

The aim of this study was to investigate biological heterogeneity between primary and metastatic ovarian cancer lesions from individual patients as a means of elucidating steps in clinical progression. Cancer tissue from 61 untreated patients with ovarian surface epithelial-stromal tumours was examined. p53 expression detected immunocytochemically by the PAb1801 antibody, DNA content evaluated by flow cytometry, and cell proliferation evaluated as the [3H]thymidine labelling index were investigated in primary tumours and corresponding synchronous metastases. The frequency of p53 positivity was similar in primary (62%) and metastatic (66%) sites, with an agreement between the two lesions from the same patient in 97% of the cases. Similarly, aneuploidy frequency (80%) and DNA indices were superimposable in primary and metastatic lesions from the same patient, with a 94% agreement. The frequency of aneuploidy was higher in p53-positive than in p53-negative lesions. An overall poor agreement (rs = 0.44) was observed for proliferative activity of primary and metastatic lesions, due to a heterogeneous profile in omental with respect to primary tumours, which was mainly evident in p53-positive cancers. Conversely, cell proliferation of peritoneal, abdominal and pelvic lesions was qualitatively similar to that of the primary tumour in 88% of patients.