Assessment of atmospheric microbial contamination in a mobile dental unit.

INTRODUCTION: Bioaerosols are important considerations in infection control as well as in occupational health. Bioaerosols may carry potentially hazardous microbes, viruses, fungi, allergens, and other toxic substances that may harm the dental operator, patient, and the dental assistant by causing nosocomial infections. OBJECTIVE: To assess the level of atmospheric microbial contamination before, during, and after dental treatment procedures in the dental operatory of a mobile dental unit (MDU). MATERIALS AND METHODS: The study included three treatment sessions on different working days, with an interval of one month. The MDU was fumigated before the start of the study. Brain Heart Infusion Agar with 5% sheep blood was used to collect the gravitometric settling of aerosols produced before, during, and after dental treatment procedures. The agar plates were sent for aerobic and anaerobic culture. RESULTS: The results showed that atmospheric microbial contamination (CFUs/plate) was 4 times higher during working sessions as compared to the levels before the working sessions. At the end of the working day, aerosols decreased by almost 3 times that seen during work. CONCLUSION: The aerosols increased during and after work sessions. This shows the increased risk of transmission of infectious agents to the dentists who work in the MDU. Hence, all necessary preventive measures should be advised and need to be followed strictly.     

Effects of protective immune serum on the yields of parasites and pulmonary cell reactions in schistosome-infected rats

Yields of parasites during the period of worm migration from the lungs to the portal circulation were measured in S. mansoni-infected Fischer rats passively immunized with protective serum from twice-infected donor rats. Two effects of protective serum were observed in recipient rats relative to normal serum recipients: yields of schistosomula from lungs were higher and yields of (immature) worms from the portal circulation were lower throughout the period analyzed. Histopathological analysis of lung tissue confirmed the presence of greater numbers of schistosomula in lungs of passively immunized rats. In addition, the percent of lung schistosomula involved in all categories of inflammatory reactions was greater in recipients of protective rat serum. The kinetics of accumulation of worms perfused from the portal circulation of normal and passively immunized rats indicate that in the latter group a smaller fraction of worms successfully migrates to the portal circulation. These findings support the hypothesis that protective activity of the serum prevents a portion of worms from successfully completing migration from the lung to the portal circulation.     

Borrelia burgdorferi OspC protein required exclusively in a crucial early stage of mammalian infection

This study demonstrates a strict temporal requirement for a virulence determinant of the Lyme disease spirochete Borrelia burgdorferi during a unique point in its natural infection cycle, which alternates between ticks and small mammals. OspC is a major surface protein produced by B. burgdorferi when infected ticks feed but whose synthesis decreases after transmission to a mammalian host. We have previously shown that spirochetes lacking OspC are competent to replicate in and migrate to the salivary glands of the tick vector but do not infect mice. Here we assessed the timing of the requirement for OspC by using an ospC mutant complemented with an unstable copy of the ospC gene and show that B. burgdorferi's requirement for OspC is specific to the mammal and limited to a critical early stage of mammalian infection. By using this unique system, we found that most bacterial reisolates from mice persistently infected with the initially complemented ospC mutant strain no longer carried the wild-type copy of ospC. Such spirochetes were acquired by feeding ticks and migrated to the tick salivary glands during subsequent feeding. Despite normal behavior in ticks, these ospC mutant spirochetes did not infect naive mice. ospC mutant spirochetes from persistently infected mice also failed to infect naive mice by tissue transplantation. We conclude that OspC is indispensable for establishing infection by B. burgdorferi in mammals but is not required at any other point of the mouse-tick infection cycle.     

In vivo liver tracking with a high volume rate 4D ultrasound scanner and a 2D matrix array probe

The effectiveness of intensity-modulated radiation therapy (IMRT) is compromised by involuntary motion (e.g. respiration, cardiac activity). The feasibility of processing ultrasound echo data to automatically estimate 3D liver motion for real-time IMRT guidance was previously demonstrated, but performance was limited by an acquisition speed of 2 volumes per second due to hardware restrictions of a mechanical linear array probe. Utilizing a 2D matrix array probe with parallel receive beamforming offered increased acquisition speeds and an opportunity to investigate the benefits of higher volume rates. In?vivo livers of three volunteers were scanned with and without respiratory motion at volume rates of 24 and 48 Hz, respectively. Respiration was suspended via voluntary breath hold. Correlation-based, phase-sensitive 3D speckle tracking was applied to consecutively acquired volumes of echo data. Volumes were omitted at fixed intervals and 3D speckle tracking was re-applied to study the effect of lower scan rates. Results revealed periodic motion that corresponded with the heart rate or breathing cycle in the absence or presence of respiration, respectively. For cardiac-induced motion, volume rates for adequate tracking ranged from 8 to 12 Hz and was limited by frequency discrepancies between tracking estimates from higher and lower frequency scan rates. Thus, the scan rate of volume data acquired without respiration was limited by the need to sample the frequency induced by the beating heart. In respiratory-dominated motion, volume rate limits ranged from 4 to 12 Hz, interpretable from the root-mean-squared deviation (RMSD) from tracking estimates at 24 Hz. While higher volume rates yielded RMSD values less than 1 mm in most cases, lower volume rates yielded RMSD values of 2-6 mm.     

The use of suture anchors in repair of the ruptured patellar tendon: a biomechanical study

BACKGROUND: Rupture of the patellar tendon is a disabling injury that usually requires surgical treatment. The standard method of repair involves placing suture loops through transpatellar tunnels. The use of suture anchors in patellar tendon repair has not been previously described. HYPOTHESIS: No difference exists in the amount of gap formation during cyclic loading or in ultimate load-to-failure strength between repairs performed with anchors and those performed with 2 types of transpatellar sutures. STUDY DESIGN: Controlled laboratory study. METHODS: Six matched pairs of cadaveric knees were tested in a custom biomechanical apparatus based on an established model. Repairs were performed using either suture anchors with No. 2 FiberWire or transpatellar suture tunnels using 2 different types of suture-No. 5 Ethibond and No. 2 FiberWire. Gap formation across the repair site during 250 cycles of extension as well as ramp-up load to failure were measured for each repair. RESULTS: The mean total gap formation across the repair site at 250 cycles was 4.1 +/- 1.9 mm for the suture anchor group, 6.7 +/- 1.8 mm for the FiberWire tunnel group, and 8.5 +/- 2.7 mm for the Ethibond tunnel group. Mean load to failure was 779 +/- 183 N, 730 +/- 83 N, and 763 +/- 231 N, respectively. CONCLUSION: Significantly less gap formation throughout 250 cycles (P = .009) and no difference in load to failure occurred with patellar tendon repairs performed with suture anchors as compared with repairs performed with transpatellar tunnels. CLINICAL RELEVANCE: The newly described method, using suture anchors for repair of patellar tendon ruptures, may be clinically equal or superior to the established method of using transpatellar tunnels.     

Chondrosarcoma of the bones of the feet

Twelve chondrosarcomas of the bones of the feet from 11 patients in the Scottish Bone Tumor Registry were reviewed. One patient with diaphyseal aclasis (osteochondromatosis) developed 2 chondrosarcomas. The mean age of patients was 52.3 years (range, 17 to 83 years). Men were predominantly affected. Four tumors affected the tarsal bones; the rest involved the short tubular bones. The usual clinical presentation was a painful, progressively enlarging swelling. Radiologically, most showed some bone expansion, cortical destruction with indistinct margins, and soft-tissue extension. Histologically, the majority were middle-grade tumors. Treatment included curettage or local excision for 4 tumors and amputation or ray resection for 8 tumors. Follow-up varied from 6 months to 18 years (average, 5.8 years). Local recurrence after surgery was seen in 3 patients. All 3 died because of metastases to the lungs or brain.     

A case of mucormycosis limited to the parotid gland

BACKGROUND: Mucormycosis is a rare fungal infection commonly affecting structures in the head and neck such as air sinuses, orbits, and the brain. Common predisposing factors include diabetes and immunosuppression. To date, only one case of mucormycosis involving the parotid gland has been reported, and this infection was associated with a fatal outcome. METHODS: We report a case of parotid gland mucormycosis in a 45-year-old woman with type 2 diabetes, who was successfully treated with a superficial parotidectomy and intravenous amphotericin B. RESULTS: After initial surgical and antifungal therapy, the patient was left with a residual facial nerve palsy for which multiple sling procedures were performed. She is currently alive and well 6 years after the diagnosis of mucormycosis. CONCLUSIONS: Mucormycosis of the parotid gland is a rare form of this often-fatal infection. In this case, infection remained isolated to the parotid gland and was diagnosed soon after presentation. The patient most likely survived because of the early diagnosis, successful surgical removal of all infected tissue, use of intravenous amphotericin therapy, and the aggressive management of comorbidities such as her diabetes.