Lymphoid depletion in ileal loops: mechanism and clinical implications

Recent long-term follow-up studies of children undergoing ileal loop urinary diversion have shown a number of complications arising in these patients: recurrent urinary tract infections, deteriorating renal function, and late midloop stricture. We suggest that all three may be related to the same underlying problem, namely, a severe depletion of lymphoid elements in the intestine. In both clinical and animal studies urine exposure to intestinal segments resulted in a marked depletion of lymphoid elements from the Peyer's patches and from beneath the intestinal villi in the intestine. In addition there was an associated hypertrophy of the lymph nodes in the ileal loop mesentery. When the intestine was no longer exposed to urine, there was a prompt regeneration and reappearance of the lymphoid elements. The lymphocytes seemed to "home in" on the submucosal areas and reform Peyer's patches once the urine was removed. The hyperplastic lymph nodes in the ileal loop mesentery regressed when urine exposure was removed. Conventional treatment of ileal loop infections focuses on the upper urinary tracts. Mid-loop stenoses are treated by resection and creation of a new ileal loop conduit. Local therapy in the form of antibiotics and/or steroid enemas may relieve some late midloop obstruction and prevent further damage to renal parenchyma.     

Fungal endophyte-infected grasses: Alkaloid accumulation and aphid response

The occurrence of the alkaloidsN-formyl andN-acetyl loline, peramine, lolitrem B, and ergovaline and the response of aphids to plants containing these compounds were determined in species and cultivars ofFestuca,Lolium, and other grass genera infected with fungal endophytes (Acremonium spp., andEpichloe typhina). Twenty-nine of 34 host-fungus associations produced one or more of the alkaloids, most frequently peramine or ergovaline. Three alkaloids (lolines, peramine, and ergovaline) were found in tall fescue and in perennial ryegrass infected withA. coenophialum, while peramine, lolitrem B, and ergovaline were present in perennial ryegrass and in tall fescue infected withA. lolii and inF. longifolia infected withE. typhina. WhileA. coenophialum andA. lolii produced similar patterns of alkaloids regardless of the species or cultivar of grass they infected, isolates ofE. typhina produced either no alkaloids or only one or two different alkaloids in the grasses tested. Aphid bioassays indicated thatRhopalosiphum padi andSchizaphis graminum did not survive on grasses containing loline alkaloids and thatS. graminum did not survive on peramine-containing grasses. Ergovaline-containing grasses did not affect either aphid.     

Coated ultrafine precipitated CaCO3 as impact modifier extender in low molecular weight PVC

Work reported earlier had shown that the addition of 0.07 micron stearate coated ultrafine precipitated CaCO₃ (CUPCC) in medium to high molecular weight PVC resulted in a significant improvement in notched Izod impact strength. The improvement was much more dramatic when the filler loading exceeded 10 phr. The addition of CUPCC to low molecular weight PVC had practically no effect on the notched Izod impact strength at equivalent loadings. More recent studies have demonstrated that when CUPCC is added to an impact modified low molecular weight PVC, it dramatically enhances the efficiency of impact modifier. This was found to be consistent with threee general classes of commercially available impact modifiers used in this study. The ability to extend the impact modifier with CUPCC in low molecular weight PVC, which has gained a wide acceptance in injection molding operations, will result in significant cost savings. The effect of CUPCC addition on other key properties and cost benefits will also be presented.     

Microbiological and meteorological analysis of two Australian dust storms in April 2009

Dust is an important source of bioaerosols including bacteria. In this study, the microbiology and meteorology of specific dust storms in Australia were investigated. The samples were collected from two dust events in April 2009 that were characterised by intense cold fronts that entrained dust from the highly erodible and drought-stricken Mallee and Riverina regions of Victoria and central NSW. In the first storm, the dust travelled eastward over Canberra and Sydney, and in the second storm, the dust travelled east/southeastward over Canberra and Melbourne. Rain fell on both cities during the second dust storm. Dust and rain samples were collected, cultured, and the composition compared using polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE). Multiple bands were evident on DGGE indicative of a diverse microflora, and identification of several bands confirmed the presence of multiple genera and species representing three phyla. Numerous bands represented Bacillus species, and these were present in multiple dust samples collected from both Canberra and Melbourne. Interestingly, the microflora present in rain samples collected in Canberra during the second dust storm was quite different and the DGGE banding patterns from these samples clustered separately to most dust samples collected at the same time. Identification of several DGGE bands and PCR products from these rain samples indicated the presence of Pseudomonas species. These results indicate that Australian dust and rain have a diverse microflora and highlights the contribution of dust events to the distribution of microbes in the environment.     

The surgical management of giant cervicofacial lymphatic malformations

Giant cervicofacial lymphatic malformation, a potentially life-threatening congenital malformation, historically has been removed in staged resections. However, complete surgical extirpation is desirable and can be achieved with the aid of a multidisciplinary team. The authors present the case of a 12-year-old girl who had an extensively enlarged cervicofacial lymphatic malformation. Effective treatment involved aggressive surgical excision, facilitated by mandibular osteotomies to provide access to the floor of the mouth, the tongue, and the pharyngeal wall. In addition, total removal of involved facial and neck skin was performed. The remaining soft tissue defect was reconstructed primarily with an abdominal musculocutaneous free flap. In the 5 years since the procedure, there has been no recurrence. Based on this experience, excision of involved skin and mandibular access osteotomies are important techniques to help completely remove cervicofacial lymphatic malformations with oral involvement, thus potentially reducing the number of recurrences. In addition, these cases require the best efforts of a multidisciplinary team to achieve a successful result so that complete and radical excision can be performed with the hope of avoiding the pitfalls of multiple resections.     

Friction reduction by texturing of DLC coatings sliding against steel under oil lubrication

It has been demonstrated that tetrahedral amorphous carbon (ta-C) films provide excellent wear and friction properties in dry sliding. Recently the applications of ta-C coatings in lubricated conditions have become more important. The use of carbon coatings aims at reducing the wear and coefficient of friction under minimum lubrication and without hazardous lubricant additives. For optimum tribological performance, a modification of the ta-C coated surfaces is required. The present paper describes an innovative method of coated surface texturing, by which nanometer and micrometer size pores are processed by various methods. Particle masking was used for processing micrometer size pores and for controlling the coating growth conditions in order to produce nanometer size pores in the ta-C surface. The masking by particles yielded a pore geometry which varied from complex shaped channels to small individual pores. The texturing was performed by distributing metallic powder particles on the surface or by direct chemical deposition of metal particles on the substrate in prior to pulsed vacuum arc deposition. The tribological characterization was carried out by applying reciprocating friction tests with controlled lubricant replenishment, in order to simulate metal forming processes. The friction reducing effect, which was observed in the tribological tests, indicated a microlubrication effect of the textured coating surfaces.     

Fc receptor-triggered insertion of secretory granules into the plasma membrane of human neutrophils: selective retrieval during phagocytosis

We studied the kinetics of secretion in human neutrophils stimulated by IgG-opsonized zymosan. Secretion of azurophilic and specific granules was quantified measuring the appearance of the granule markers CD63 and CD66b, respectively, at the cell surface. The kinetics of secretion was compared with the course of phagocytosis, revealed by the trapping of the fluid phase marker, Lucifer Yellow, in vacuoles containing zymosan particles. We found that secretion of both azurophilic and specific granules precedes phagosome sealing. An initial rapid phase of secretion was followed by a decrease in the amount of CD63 and CD66b at the cell surface. This subsequent disappearance of surface CD63 and CD66b was inhibited by cytochalasin B and probably represents internalization of the granular markers into the forming phagosome. The decrease in the amount of CD63 and CD66b exposed at the cell surface was not accompanied by a commensurate reduction in cell surface area, measured with the amphiphilic fluorescent dye FM1-43. These findings imply that CD63 and CD66b are selectively retrieved from the plasma membrane following secretion. Evidence is also presented that calcium is not the sole mediator of the rapid secretion of azurophilic and specific granules triggered by IgG-opsonized particles and that cytochalasin does not impair signaling of the calcium transient elicited by Fc receptors. Instead, actin disassembly appears to reduce the efficiency of the interaction between opsonized particles and their receptors, an effect that can be overcome by increasing the concentration of the stimulating particles.