68 research outputs found
Bacteriological studies of blood, tissue fluid, lymph and lymph nodes in patients with acute dermatolymphangioadenitis (DLA) in course of ‘filarial’ lymphedema
Filarial lymphedema is complicated by frequent episodes of dermatolymphangioadenitis (DLA). Severe systemic
symptoms during attacks of DLA resemble those of septicemia. The question we asked was whether bacterial isolates
can be found in the peripheral blood of patients during the episodes of DLA. Out of 100 patients referred to us with
‘filarial’ lymphedema 14 displayed acute and five subacute symptoms of DLA. All were on admission blood
microfilariae negative but had a positive test in the past. Blood bacterial isolates were found in nine cases, four acute
(21%) and five subacute (26%). In 10 acute cases blood cultures were found negative. Six blood isolates belonged to
Bacilli, four to Cocci and one was Sarcina. To identify the sites of origin of bacterial dissemination, swabs taken from
the calf skin biopsy wounds and tissue fluid, lymph and lymph node specimens were cultured. Swabs from the calf
skin biopsy wound contained isolates in nine (47%) cases. They were Bacilli in nine, Cocci in three, Acinetobacter and
Erwinia in two cases. Tissue fluid was collected from 10 patients and contained Bacilli in four (40%) and
Staphylococci in three (30%). Lymph was drained in four patients and contained isolates in all samples (100%). They
were Staphylococcus epidermis, xylosus and aureus, Acinetobacter, Bacillus subtilis and Sarcina. Three lymph nodes
were biopsied and contained Staphylococcus chromogenes, xylosus, Enterococcus and Bacillus cereus. In six cases the
same phenotypically defined species of bacteria were found in blood and limb tissues or fluids. In the ‘control’ group of patients with lymphedema without acute or subacute changes all blood cultures were negative. Interestingly, swabs
from biopsy wound of these patients contained isolates in 80%, tissue fluid in 68%, lymph in 70% and lymph nodes
in 58% of cases. In healthy controls, tissue fluid did not contain bacteria, and lymph isolates were found only in 12%
of cases. This study demonstrates that patients with acute episodes of DLA reveal bacteriemia in a high percentage
of cases. Diversity of blood and tissue bacterial isolates in these patients points to a breakdown of the skin immune
barrier in lymphedema and subsequently indiscriminate bacterial colonization of deep tissues and spread to an blood
circulation. © 1999 Elsevier Science B.V. All rights reserved
Actively Controlling Buffet-Induced Excitations
High performance aircraft, especially those with twin vertical tails, encounter unsteady buffet loads when flying at high angles of attack. These loads result in significant random stresses, which may cause fatigue damage leading to restricted capabilities and availability of the aircraft. An international collaborative research activity among Australia, Canada and the United States, conducted under the auspices of The Technical Cooperation Program (TTCP) contributed resources toward a program that coalesced a broad range of technical knowledge and expertise into a single investigation to demonstrate the enhanced performance and capability of the advanced active BLA control system in preparation for a flight test demonstration. The research team investigated the use of active structural control to alleviate the damaging structural response to these loads by applying advanced directional piezoelectric actuators, the aircraft rudder, switch mode amplifiers, and advanced control strategies on an F/A-18 aircraft empennage. Some results of the full-scale investigation are presented herein
Controlling Buffeting Loads by Rudder and Piezo-Actuation
High performance aircraft, especially those with twin vertical tails, encounter unsteady buffet loads when flying at high angles of attack. These stochastic loads result in significant stresses, which may cause fatigue damage leading to restricted capabilities and availability of the aircraft. An international collaborative research activity among Australia, Canada and the United States, conducted under the auspices of The Technical Cooperation Program (TTCP) contributed resources toward a program that coalesced a broad range of technical knowledge and expertise into a single investigation to demonstrate the enhanced performance and capability of the advanced active Buffet Load Alleviation ( ) control system in preparation for a flight test demonstration. The research team investigated the use of active structural control to alleviate the damaging structural response to these loads by applying advanced directional piezoelectric actuators, the aircraft rudder, switch mode amplifiers, and advanced control strategies on an F/A-18 aircraft empennage. Some results of the full-scale investigation are presented herein
Temporal, spatial, and structural patterns of adult trembling aspen and white spruce mortality in Quebec's boreal forest
Temporal, spatial, and structural patterns of adult trembling aspen (Populus tremuloides Michx.) and white spruce (Picea glauca (Moench) Voss) mortality were studied in intact 150-year-old stands in the southwestern boreal forest of Quebec. For both species, mortality decreases (number of dead trees/total number of trees) with distance from the lake edge until 100-150 m, from which point it slightly increases. Strong peaks in mortality were found for 40- to 60-year-old aspen mainly between 1974 and 1992. Such mortality in relatively young aspen is likely related to competition for light from the dominant canopy trees. Also, the recruitment of this young aspen cohort is presumably the result of a stand breakup that occurred when the initial aspen-dominated stand was between 90 and 110 years old. For spruce, strong peaks in mortality were found in 110- to 150-year-old trees and they occurred mainly after 1980. No clear explanation could be found for these peaks, but we suggest that they may be related to senescence or weakening of the trees following the last spruce budworm outbreak. Suppressed and codominant aspen had a much higher mortality ratio than spruce in the same height class, while more surprisingly, no difference in mortality rate was found between dominant trees of the two species. Most spruce trees were found as standing dead, which leads us to reject the hypothesis that windthrow is an important cause of mortality for spruce in our forests
RecombinantWolbachia surface protein (WSP)-induced T cell responses in Wuchereria bancrofti infections
Human lymphatic filariasis is a debilitating parasitic
disease characterized by downregulation of the host’s
immune response in asymptomatic carriers along with
profound hyperreactivity in chronic patients apart from
putatively immune endemic normals. The endosymbiont
Wolbachia, a bacterium of filarial nematodes has received
much attention as possible chemotherapeutic target and its
involvement in disease pathogenesis. The role of recombinant
Wolbachia surface protein (rWSP), one of the most
abundantly expressed proteins of the endosymbiont, in
modulating cell-mediated immune responses in patients
harboring Wuchereria bancrofti infections was evaluated in
the current study. rWSP-induced lymphoproliferation with
peripheral blood mononuclear cells suggested an impaired
proliferative response in asymptomatic microfilaremic (MF)
and symptomatic chronic pathology (CP) patients compared
to endemic normals (EN). This was further supported by a significantly diminished expression of CD69 along with
elevated levels of CD127 and CD62L in filarial patients
(MF and CP) compared to EN. Further, rWSP induced
the expression of regulatory T cell markers CTLA-4 and
CD25 along with suppressor cytokines IL-10 and TGF-β
in MF and CP patients compared to EN. However, the
rWSP-stimulated expression of IFN-γ was diminished
significantly in filarial patients compared to endemic
normals. Thus, these findings suggest that WSP may also
contribute to the suppression of immune responses seen
in filarial patients
Management of genital manifestations of lymphatic filariasis
Genital lymphedema secondary to filariasis is a common problem in most of the filarial endemic regions of the world. Repeated filarial attacks lead to obstruction of lymph flow resulting in various types of genital manifestations in both males and females. Currently there is no cure for lymphedema. As yet no operative procedure has restored normal lymphatic function, and significant swelling recurs after all of the currently available approaches. Progress has been made by micro-lymphatic operations combined with conservative measures to relieve many of these patients of much of their swelling without resort to lifetime use of conservative measures
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