Deep Tissue Sites Research Articles

The Maintenance of High Affinity Plasminogen Binding by Group A Streptococcal Plasminogen-binding M-like Protein Is Mediated by Arginine and Histidine Residues within the a1 and a2 Repeat Domains

Subversion of the plasminogen activation system is implicated in the virulence of group A streptococci (GAS). GAS displays receptors for the human zymogen plasminogen on the cell surface, one of which is the plasminogen-binding group A streptococcal M-like protein (PAM). The plasminogen binding domain of PAM is highly variable, and this variation has been linked to host selective immune pressure. Site-directed mutagenesis of full-length PAM protein from an invasive GAS isolate was undertaken to assess the contribution of residues in the a1 and a2 repeat domains to plasminogen binding function. Mutagenesis to alanine of key plasminogen binding lysine residues in the a1 and a2 repeats (Lys98 and Lys111) did not abrogate plasminogen binding by PAM nor did additional mutagenesis of Arg101 and His102 and Glu104, which have previously been implicated in plasminogen binding. Plasminogen binding was only abolished with the additional mutagenesis of Arg114 and His115 to alanine. Furthermore, mutagenesis of both arginine (Arg101 and Arg114) and histidine (His102 and His115) residues abolished interaction with plasminogen despite the presence of Lys98 and Lys111 in the binding repeats. This study shows for the first time that residues Arg101, Arg114, His102, and His115 in both the a1 and a2 repeat domains of PAM can mediate high affinity plasminogen binding. These data suggest that highly conserved arginine and histidine residues may compensate for variation elsewhere in the a1 and a2 plasminogen binding repeats, and may explain the maintenance of high affinity plasminogen binding by naturally occurring variants of PAM.

Immunohistochemical analysis of anaplastic lymphoma kinase expression in deep soft tissue calcifying fibrous pseudotumor: evidence of a late sclerosing stage of inflammatory myofibroblastic tumor?

Calcifying fibrous pseudotumor (CFT) is a rare benign soft tissue lesion composed of dense hyalinized fibrous tissue containing bland spindle-shaped cells admixed with a lymphoplasmacytic infiltrate and foci of dystrophic and often psammomatous calcifications. It has been suggested that CFT represents a late sclerosing stage of inflammatory myofibroblastic tumor (IMT). Recently, clonal cytogenetic abnormalities involving the anaplastic lymphoma kinase (ALK) gene on chromosome 2p have been identified in IMT, particularly those arising in deep soft tissue sites. We evaluated seven cases of deep soft tissue CFT diagnosed at the Cleveland Clinic Foundation and the University of Florida with available paraffin-embedded blocks using a monoclonal antibody to ALK (Dako, Carpenteria, CA) and a modified avidin-biotin complex method. The cohort included six women and one man with a median age at diagnosis of 43 years (range, 26 to 67 years). Sites of CFT included mesentery (3), peritoneum (1), omentum (1), serosa of small bowel (1), and anterior mediastinum (1). Immunohistochemically, only one case showed focal staining for ALK. The remaining six cases were negative, with appropriate positive and negative control staining. In conclusion, unlike IMT, CFT in deep soft tissue locations rarely expresses ALK by immunohistochemistry, suggesting that CFT is a different clinicopathologic entity than IMT, as opposed to representing a "burned out" IMT. Ann Diagn Pathol 5:10-14, 2001.

Subversion of integrins by enteropathogenic Yersinia.

Enteropathogenic Yersinia are gram-negative bacterial species that translocate from the lumen of the intestine and are able to grow within deep tissue sites. During the earliest stages of disease, the organism is able to bind integrin receptors that are presented on the apical surface of M cells in the intestine, which allows its internalization and subsequent translocation into regional lymph nodes. The primary integrin substrate is the outer-membrane protein invasin, which binds with extraordinarily high affinity to at least five different integrins that have the (beta)(1) chain. Bacterial uptake into host cells is modulated by the affinity of receptor-substrate interaction, receptor concentration and the ability of the substrate to aggregate target receptors.

Plasma Pharmacokinetics and Tissue Penetration of Alatrofloxacin in Morbidly Obese Individuals.

To characterise the peritoneal and subcutaneous adipose penetration of alatrofloxacin. If the extent of penetration of this lipophilic fluoroquinolone is adequate in patients with extensive adipose layers, it may provide better antimicrobial coverage than more commonly used antibiotics that are less lipophilic. Six morbidly obese individuals undergoing a Roux-Y gastric bypass procedure received single 1-hour infusions of alatrofloxacin equivalent to 300mg of its active metabolite, trovafloxacin. Blood samples were obtained over a 24-hour period and adipose tissue from subcutaneous and deep tissue sites were obtained approximately 3 hours post-infusion of alatrofloxacin. Plasma and adipose tissue concentrations of trovafloxacin were determined by high pressure liquid chromatography with fluorescence detection. The mean maximum plasma concentration, area under the concentration-time curve, and elimination half-life of trovafloxacin were 3.6 mg/L, 37.4 mg/L·h, and 12.1h, respectively. The mean tissue concentrations at the subcutaneous and deep adipose sites were 0.43 and 0.41 μ/g, respectively. These results indicated that the pharmacokinetics of trovafloxacin in morbidly obese individuals are similar to those in healthy control individuals. In addition, the concentrations of trovafloxacin achieved in the adipose tissue were above the minimum inhibitory concentration of most pathogens responsible for surgical and decubitus ulcer infections.

Tissue radiation dosages using the RVG-S with and without niobium filtration.

Tissue doses for a modified Rando head- and-neck phantom were measured for imaging with speed group E film with standardized aluminium filtration and the RVG-S both with and without added niobium filtration. Cylindrical holes drilled into the phantom's tissue-equivalent material permitted the placement of a small ionization chamber into anatomically correct sites representing the thyroid, parotid, submandibular and sublingual glands. To establish the necessary cone positions, angulations and time settings for each exposure, diagnostically acceptable images of six teeth, representative of different intraoral regions, were made for a DXXTR mannequin. Entrance and exit points were marked and transferred to the phantom to allow reproducible repeat exposures. The RVG-S provided reductions in average skin entrance dose of 31 per cent to 39 per cent with standard aluminium filtration and 51 per cent to 60 per cent with the addition of niobium filtration to attenuate the beam. While dose reductions relative to E-speed film usage were found for deep tissue sites, these were site and projection specific. The cumulative reduction from use of the RVG-S without niobium filtration was 32 per cent. It was 42 per cent with additional niobium filtration. It should be noted, however, that adding niobium filtration resulted in increased dosages to the deeper soft tissues such as the thyroid gland.