Amyloid histology stain for rapid bacterial endospore imaging

Bacterial endospores are some of the most resilient forms of life known to us, with their persistent survival capability resulting from a complex and effective structural organization. The outer membrane of endospores is surrounded by the densely packed endospore coat and exosporium, containing amyloid or amyloid-like proteins. In fact, it is the impenetrable composition of the endospore coat and the exosporium that makes staining methodologies for endospore detection complex and challenging. Therefore, a plausible strategy for facile and expedient staining would be to target components of the protective surface layers of the endospores. Instead of targeting endogenous markers encapsulated in the spores, here we demonstrated staining of these dormant life entities that targets the amyloid domains, i.e., the very surface components that make the coats of these species impenetrable. Using an amyloid staining dye, thioflavin T (ThT), we examined this strategy. A short incubation of bacillus endospore suspensions with ThT, under ambient conditions, resulted in (i) an enhancement of the fluorescence of ThT and (ii) the accumulation of ThT in the endospores, affording fluorescence images with excellent contrast ratios. Fluorescence images revealed that ThT tends to accumulate in the surface regions of the endospores. The observed fluorescence enhancement and dye accumulation, coupled with the sensitivity of emission techniques, provide an effective and rapid means of staining endospores without the inconvenience of pre- or posttreatment of samples.     

Prevalence of Internal Hernias After Laparoscopic Colonic Surgery

Introduction  Laparoscopic approach for colorectal resections is gaining popularity. Internal small bowel herniation (SBH) through a mesenteric defect has been described and, although rare, is a severe complication. The aim of this study was to evaluate the incidence and outcome of internal hernias after laparoscopic colorectal resection. Material and methods  During a 5-year period, all patients who underwent laparoscopic left colon resection were included in the study. A retrospective data base query was performed searching for all patients in whom SBH required surgical reintervention. Results  A total of 436 laparoscopic left colorectal resections were performed from January 2000 to July 2006. Five male patients presented symptomatic internal hernias and required re-operation. Four had a resection for cancer and one for sigmoiditis. The mesenteric defect was not initially closed in three cases. In all cases, we found small bowel hernias through the mesocolon defect. One patient was re-operated on post-op day 2 for mesenteric ischemia and died after 24 h. Discussion  Internal hernia is a rare but fatal complication after laparoscopic colonic resection. Suspicion of this diagnosis requires emergency re-operation because symptoms are nonspecific. Conclusion  All mesenteric defects created during colorectal laparoscopy surgery should be meticulously closed. SAGES April 2007, Las Vegas     

Ameloblastic fibrosarcoma of the maxillary sinus in an infant: a case report with long-term follow-up

Ameloblastic fibrosarcoma (AFS) or ameloblastic sarcoma is an extremely rare odontogenic neoplasm. The authors report AFS in the maxillary sinus of a 4-month-old boy. The tumor was composed of odontogenic epithelium, resembling that of ameloblastoma, and a mesenchymal part exhibiting features of fibrosarcoma. We also found some areas with deposition of dentinoid material closely adjacent to the ameloblastic epithelium. Although AFS has occurred in a wide age range, this is the first report of this tumor in infancy with long-term follow-up.     

Emergence of mupirocin-resistant MRSA among Iranian clinical isolates

Mupirocin is a topical antimicrobial agent which is increasingly used for the treatment and eradication of Staphylococcus aureus colonization from the noses of patients and hospital staff. However, the extensive use of this antibiotic has given rise to mupirocin resistance in S. aureus. The present study evaluated the rate of mupirocin resistance in S. aureus clinical isolates from burns patients. A total of 125 S. aureus nonduplicate consecutive clinical isolates were collected from the burns patients in Iranian Burns Hospital, and the presence of mecA and mupA genes was assessed through polymerase chain reaction. From the 125 isolates, 107 (85.6 %) and 40 (32 %) had the mecA and mupA genes, respectively. The high prevalence of mupirocin-resistant S. aureus in this burns hospital in comparison with other general hospitals in Iran requires revision in the current mupirocin therapy strategies. In tandem with other countries, the rate of mupirocin resistance is increasing in Iran, which necessitates regular monitoring.     

Laser-induced collagen remodeling and deposition within the basilar membrane of the mouse cochlea

The cochlea is the mammalian organ of hearing. Its predominant vibratory element, the basilar membrane, is tonotopically tuned, based on the spatial variation of its mass and stiffness. The constituent collagen fibers of the basilar membrane affect its stiffness. Laser irradiation can induce collagen remodeling and deposition in various tissues. We tested whether similar effects could be induced within the basilar membrane. Trypan blue was perfused into the scala tympani of anesthetized mice to stain the basilar membrane. We then irradiated the cochleas with a 694-nm pulsed ruby laser at 15 or 180 Jcm(2). The mice were sacrificed 14 to 16 days later and collagen organization was studied. Polarization microscopy revealed that laser irradiation increased the birefringence within the basilar membrane in a dose-dependent manner. Electron microscopy demonstrated an increase in the density of collagen fibers and the deposition of new fibrils between collagen fibers after laser irradiation. As an assessment of hearing, auditory brainstem response (ABR) thresholds were found to increase moderately after 15 Jcm(2) and substantially after 180 Jcm(2). Our results demonstrate that collagen remodeling and new collagen deposition occurs within the basilar membrane after laser irradiation in a similar fashion to that found in other tissues.     

Glycoprotein Ib–IX-mediated activation of integrin αIIbβ3: effects of receptor clustering and von Willebrand factor adhesion

Summary. The interaction between the platelet glycoprotein (GP) Ib–IX complex and von Willebrand factor (VWF) initiates both hemostasis and pathological thrombosis. This interaction is not only the first adhesive event of platelets at sites of vessel injury, but also facilitates fibrinogen binding to α_IIbβ₃, which subsequently results in platelet aggregation. Since it has been suggested that GP Ib–IX clustering may promote platelet activation, we investigated the effect of such clustering on both VWF–GP Ib–IX and fibrinogen–α_IIbβ₃ bonds using optical tweezers. In our system, fusion of tandem repeats of FK506‐binding protein (FKBP) to the cytoplasmic tail of the GP IX subunit of the GP Ib–IX complex allowed subsequent receptor clustering within the plasma membrane by the bivalent, cell‐permeant small molecule ligand AP20187. We measured binding forces between polystyrene beads coated with either plasma‐derived VWF or the VWF A1 domain and GP Ib–IX(FKBP)₂, and those between fibrinogen‐coated beads and α_IIbβ₃ expressed on Chinese hamster ovary cells. The minimal detachment force between GP Ib–IX(FKBP)₂ and A1 or plasma‐derived VWF doubled after AP20187 was added. The binding force between immobilized fibrinogen and α_IIbβ₃ was not changed by the clustering agent; however, the strength of single fibrinogen–α_IIbβ₃ bonds increased significantly after ligation of GP Ib–IX(FKBP)₂ by A1. These results demonstrate that GP Ib–IX clustering increases the overall strength of its interaction with VWF. Furthermore, signals from GP Ib–IX can activate α_IIbβ₃, thereby increasing the strength of its interaction with fibrinogen.