Bacteriophage inactivation at the air-water-solid interface in dynamic batch systems.
Bacteriophages have been widely used as surrogates for human enteric viruses in many studies on virus transport and fate. In this investigation, the fates of three bacteriophages, MS2, R17, and phiX174, were studied in a series of dynamic batch experiments. Both MS2 and R17 readily underwent inactivation in batch experiments where solutions of each phage were percolated through tubes packed with varying ratios of glass and Teflon beads. MS2 and R17 inactivation was the result of exposure to destructive forces at the dynamic air-water-solid interface. phiX174, however, did not undergo inactivation in similar studies, suggesting that this phage does not accumulate at air-water interfaces or is not affected by interfacial forces in the same manner. Other batch experiments showed that MS2 and R17 were increasingly inactivated during mixing in polypropylene tubes as the ionic strength of the solution was raised (phiX174 was not affected). By the addition of Tween 80 to suspensions of MS2 and R17, phage inactivation was prevented. Our data suggest that viral inactivation in simple dynamic batch experiments is dependent upon (i) the presence of a dynamic air-water-solid interface (where the solid is a hydrophobic surface), (ii) the ionic strength of the solution, (iii) the concentration of surface active compounds in the solution, and (iv) the type of virus used. (+info)
Transponder-induced sarcoma in the heterozygous p53+/- mouse.
Heterozygous p53+/- transgenic mice are being studied for utility as a short-term alternative model to the 2-yr rodent carcinogenicity bioassay. During a 26-wk study to assess the potential carcinogenicity of oxymetholone using p-cresidine as a positive control, glass/polypropylene microchips (radio transponder identification devices) were subcutaneously implanted into male and female p53+/- mice. During week 15, the first palpable mass was clinically observed at an implant site. This rapidly growing mass virtually quadrupled in size by week 25. Microscopic examination of all implant sites revealed that 18 of 177 animals had a subcutaneous histologically malignant sarcoma. The neoplasms were characterized as undifferentiated sarcomas unrelated to drug treatment, as indicated by the relatively even distribution among dose groups, including controls. An unusual preneoplastic mesenchymal change characterized by the term "mesenchymal dysplasia" was present in most groups and was considered to be a prodromal change to sarcoma development. The tumors were observed to arise from dysplastic mesenchymal tissue that developed within the tissue capsule surrounding the transponder. The preneoplastic changes, including mesenchymal dysplasia, appeared to arise at the transponder's plastic anchoring barb and then progressed as a neoplasm to eventually surround the entire microchip. Capsule membrane endothelialization, inflammation, mesenchymal basophilia and dysplasia, and sarcoma were considered unequivocal preneoplastic/neoplastic responses to the transponder and were not related to treatment with either oxymetholone or p-cresidine. (+info)
Surgical treatment of tracheal collapse using pliable total ring prostheses: results in one experimental and 4 clinical cases.
Pliable total ring prostheses were created from the polyvinyl chloride drip chambers of intravenous administration sets. The total ring prostheses were placed in one clinically normal research dog and in 4 client-owned dogs diagnosed with tracheal collapse. The research dog was euthanized one month after placement of the prostheses. Histopathological analysis of the trachea adjacent to the prostheses revealed a mild inflammatory response. The follow-up period for the clinical cases was from 4 months to 11 years. Radiographs taken and fluoroscopy performed 1 day to 5 months after surgery revealed improvement or resolution of the tracheal collapse. One dog was asymptomatic 28 weeks following surgery. Two dogs died 7 and 9 years after surgery, with one requiring intermittent medical management for coughing. They were euthanized for nonrespiratory illness. One dog had a persistent nonproductive cough, due to collapse of the mainstem bronchi, when last evaluated 4 months postoperatively. Pliable total ring prostheses provided adequate stability to the trachea and had the advantage of conforming to the trachea and being easy to create, place, and suture. (+info)
Zona pellucida damage to human embryos after cryopreservation and the consequences for their blastomere survival and in-vitro viability.
The study objective was to quantify zona pellucida (ZP) damage in cryopreserved human embryos. The influence of two different freezing containers was investigated, and the influence of freezing damage on the survival and viability of the embryos evaluated. ZP damage did not differ according to whether embryos originated from in-vitro fertilization (IVF) cycles or from IVF cycles in association with intracytoplasmic sperm injection (ICSI). The freezing container, however, significantly influenced the occurrence of ZP damage after cryopreservation. More damage was observed when the embryos were frozen-thawed using plastic cryovials than using plastic mini-straws (16.6% versus 2.3%; P < 0.0001). A clear association was found between blastomere survival and ZP intactness. Consequently, the percentage of embryos with 100% blastomere survival was higher when embryos were frozen-thawed using plastic mini-straws. The further cleavage of frozen-thawed embryos suitable for transfer was not different whether there was ZP damage or not; however, it was higher when there was 100% blastomere survival as compared with when some blastomeres were damaged (79.0% versus 43.7%; P < 0.0001). Consequently, more embryos suitable for transfer cleaved further when they were frozen-thawed using plastic mini-straws. In conclusion, the aim of a cryopreservation programme should be to have as many fully intact embryos as possible after thawing. Increased ZP damage might indicate a suboptimal cryopreservation procedure. (+info)
Survival of enterococci and staphylococci on hospital fabrics and plastic.
The transfer of gram-positive bacteria, particularly multiresistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE), among patients is a growing concern. One critical aspect of bacterial transfer is the ability of the microorganism to survive on various common hospital surfaces. The purpose of this study was to determine the survival of 22 gram-positive bacteria (vancomycin-sensitive and -resistant enterococci and methicillin-sensitive and -resistant staphylococci) on five common hospital materials: smooth 100% cotton (clothing), 100% cotton terry (towels), 60% cotton-40% polyester blend (scrub suits and lab coats), 100% polyester (privacy drapes), and 100% polypropylene plastic (splash aprons). Swatches were inoculated with 10(4) to 10(5) CFU of a microorganism, assayed daily by placing the swatches in nutritive media, and examining for growth after 48 h. All isolates survived for at least 1 day, and some survived for more than 90 days on the various materials. Smaller inocula (10(2)) survived for shorter times but still generally for days. Antibiotic sensitivity had no consistent effect on survival. The long survival of these bacteria, including MRSA and VRE, on commonly used hospital fabrics, such as scrub suits, lab coats, and hospital privacy drapes, underscores the need for meticulous contact control procedures and careful disinfection to limit the spread of these bacteria. (+info)
Polypropylene mesh substitute for the fascial defect after using for the dural repair--technical note.
Use of the anterior sheath of the rectus abdominis muscle (anterior sheath) as a dural substitute and patching of the large defect of the anterior sheath with polypropylene mesh are described. Five patients were treated using the anterior sheath and the mesh. No postoperative complications such as cerebrospinal fluid leakage, infection, or abdominal wall hernia occurred. The mesh is useful as a patch for the sheath defect. (+info)
A comparison of suture repair with mesh repair for incisional hernia.
BACKGROUND: Incisional hernia is an important complication of abdominal surgery. Procedures for the repair of these hernias with sutures and with mesh have been reported, but there is no consensus about which type of procedure is best. METHODS: Between March 1992 and February 1998, we performed a multicenter trial in which we randomly assigned to suture repair or mesh repair 200 patients who were scheduled to undergo repair of a primary hernia or a first recurrence of hernia at the site of a vertical midline incision of the abdomen of less than 6 cm in length or width. The patients were followed up by physical examination at 1, 6, 12, 18, 24, and 36 months. Recurrence rates and potential risk factors for recurrent incisional hernia were analyzed with the use of life-table methods. RESULTS: Among the 154 patients with primary hernias and the 27 patients with first-time recurrent hernias who were eligible for the study, 56 had recurrences during the follow-up period. The three-year cumulative rates of recurrence among patients who had suture repair and those who had mesh repair were 43 percent and 24 percent, respectively, with repair of a primary hernia (P=0.02; difference, 19 percentage points; 95 percent confidence interval, 3 to 35 percentage points). The recurrence rates were 58 percent and 20 percent with repair of a first recurrence of hernia (P=0.10; difference, 38 percentage points; 95 percent confidence interval, -1 to 78 percentage points). The risk factors for recurrence were suture repair, infection, prostatism (in men), and previous surgery for abdominal aortic aneurysm. The size of the hernia did not affect the rate of recurrence. CONCLUSIONS: Among patients with midline abdominal incisional hernias, mesh repair is superior to suture repair with regard to the recurrence of hernia, regardless of the size of the hernia. (+info)
Patch reconstruction of hemidiaphragm agenesis by the polypropylene mesh prosthesis.
We present a case of a middle-aged woman with right hemidiaphragm agenesis, which became evident after a blunt injury. Ultrasound, X-ray, and computed tomography confirmed the diagnosis, and the diaphragmatic congenital defect was closed by insertion of a polypropylene mesh prosthesis. (+info)