Paleomagnetism Of The Wrangellia And Alexander Terranes And The Tectonic History Of Southern Alaska

Thesis (Ph.D.) University of Alaska Fairbanks, 1984Wrangellia was the first Alaskan tectonostratigraphic terrane to be widely accepted as allochthonous with respect to North America. There is, however, considerable disagreement as to the age of emplacement of this terrane as well as the hemisphere in which it originated. Some 800 paleomagnetic samples were collected from 24 localities in southern Alaska to elucidate the paleolatitude translation history of Wrangellia and other associated terranes. Data of known polarity from the Skolai Group (Pennsylvanian/Permian) strongly suggest that Wrangellia originated at 10-15 degrees North latitude. The Permian Pybus Dolomite yields a 9 degree S paleolatitude and suggests that the Alexander terrane moved southward in late Paleozoic and Triassic time. Evaluation of geologic data indicates that the Wrangellia and Alexander terranes amalgamated in an oceanic setting in mid to Late Jurassic time. Paleomagnetism of the Brothers Volcanics (Alexander terrane) and MacColl Ridge Formation (Wrangellia) documents a low latitude for both terranes during the Cretaceous, thereby precluding a pre-Tertiary age of emplacement for the amalgamated superterrane. Speculative apparent polar wander paths for Wrangellia and the Alexander terranes, in addition to geologic and biogeographic constraints, allow development of the following hypothetical tectonic model. Both the Alexander and Wrangellia terranes originated in the northern hemisphere adjacent to western North America in mid-paleozoic and late Paleozoic times, respectively. The Alexander terrane moved into the southern hemisphere during the Paleozoic and Wrangellia began moving southward in the Late Triassic or Early Jurassic. These two terranes amalgamated in mid to low southern paleolatitudes in later Jurassic time and formed part of a composite terrane, here termed the Southern Alaska superterrane. This superterrane began northward translation in Late Jurassic time, accreting to North America in Tertiary time

Magnetostratigraphy of Cueva Del Aleman, Isla de Mona, Puerto Rico and the Species Duration of Audobon\u27s Shearwater

Magnetostratigraphic analysis of deposits exposed in Cueva del Aleman shows two reversed and two normal chronozones. The lower normal polarity event is observed in a clastic dike and probably predates initial cave formation. Sediments deposited inside the cave proper show a R-N-R sequence and probably date to at least 1.8 Ma. A fossiliferous clastic dike contains normal polarity with an overlying reversed magnetozone. Audubon’s Shearwater (bird) bones occur in the dike, which is tentatively correlated with the lower N polarity zone predating cave formation. If this correlation is correct, the Audubon’s Shearwater (Puffinus lherminieri) range can be extended back to at least 1.8 Ma, the Olduvai subchron

cytokines in the nasal washes of children with respiratory syncytial virus bronchiolitis

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Macrophages Are Required for Dendritic Cell Uptake of Respiratory Syncytial Virus from an Infected Epithelium

We have previously shown that the respiratory syncytial virus [RSV] can productively infect monocyte derived dendritic cells [MoDC] and remain dormant within the same cells for prolonged periods. It is therefore possible that infected dendritic cells act as a reservoir within the airways of individuals between annual epidemics. In the present study we explored the possibility that sub-epithelial DCs can be infected with RSV from differentiated bronchial epithelium and that in turn RSV from DCs can infect the epithelium. A dual co-culture model was established in which a differentiated primary airway epithelium on an Air Liquid Interface (ALI) was cultured on a transwell insert and MoDCs were subsequently added to the basolateral membrane of the insert. Further experiments were undertaken using a triple co-culture model in which in which macrophages were added to the apical surface of the differentiated epithelium. A modified RSV [rr-RSV] expressing a red fluorescent protein marker of replication was used to infect either the MoDCs or the differentiated epithelium and infection of the reciprocal cell type was assessed using confocal microscopy. Our data shows that primary epithelium became infected when rr-RSV infected MoDCs were introduced onto the basal surface of the transwell insert. MoDCs located beneath the epithelium did not become infected with virus from infected epithelial cells in the dual co-culture model. However when macrophages were present on the apical surface of the primary epithelium infection of the basal MoDCs occurred. Our data suggests that RSV infected dendritic cells readily transmit infection to epithelial cells even when they are located beneath the basal layer. However macrophages appear to be necessary for the transmission of infection from epithelial cells to basal dendritic cells

Persistence of lung inflammation and lung cytokines with high-resolution CT abnormalities during recovery from SARS

BACKGROUND: During the acute phase of severe acute respiratory syndrome (SARS), mononuclear cells infiltration, alveolar cell desquamation and hyaline membrane formation have been described, together with dysregulation of plasma cytokine levels. Persistent high-resolution computed tomography (HRCT) abnormalities occur in SARS patients up to 40 days after recovery. METHODS: To determine further the time course of recovery of lung inflammation, we investigated the HRCT and inflammatory profiles, and coronavirus persistence in bronchoalveolar lavage fluid (BALF) of 12 patients at recovery at 60 and 90 days. RESULTS: At 60 days, compared to normal controls, SARS patients had increased cellularity of BALF with increased alveolar macrophages (AM) and CD8 cells. HRCT scores were increased and correlated with T-cell numbers and their subpopulations, and inversely with CD4/CD8 ratio. TNF-α, IL-6, IL-8, RANTES and MCP-1 levels were increased. Viral particles in AM were detected by electron microscopy in 7 of 12 SARS patients with high HRCT score. On day 90, HRCT scores improved significantly in 10 of 12 patients, with normalization of BALF cell counts in 6 of 12 patients with repeat bronchoscopy. Pulse steroid therapy and prolonged fever were two independent factors associated with delayed resolution of pneumonitis, in this non-randomized, retrospective analysis. CONCLUSION: Resolution of pneumonitis is delayed in some patients during SARS recovery and may be associated with delayed clearance of coronavirus, Complete resolution may occur by 90 days or later

The interferon gamma gene polymorphism +874 A/T is associated with severe acute respiratory syndrome

BACKGROUND: Cytokines play important roles in antiviral action. We examined whether polymorphisms of IFN-γ,TNF-α and IL-10 affect the susceptibility to and outcome of severe acute respiratory syndrome (SARS). METHODS: A case-control study was carried out in 476 Chinese SARS patients and 449 healthy controls. We tested the polymorphisms of IFN-γ,TNF-α and IL-10 for their associations with SARS. RESULTS: IFN-γ +874A allele was associated with susceptibility to SARS in a dose-dependent manner (P < 0.001). Individuals with IFN-γ +874 AA and AT genotype had a 5.19-fold (95% Confidence Interval [CI], 2.78-9.68) and 2.57-fold (95% CI, 1.35-4.88) increased risk of developing SARS respectively. The polymorphisms of IL-10 and TNF-α were not associated with SARS susceptibility. CONCLUSION: IFN-γ +874A allele was shown to be a risk factor in SARS susceptibility

Calf health from birth to weaning. III. housing and management of calf pneumonia

Calfhood diseases have a major impact on the economic viability of cattle operations. A three part review series has been developed focusing on calf health from birth to weaning. In this paper, the last of the three part series, we review disease prevention and management with particular reference to pneumonia, focusing primarily on the pre-weaned calf. Pneumonia in recently weaned suckler calves is also considered, where the key risk factors are related to the time of weaning. Weaning of the suckler calf is often combined with additional stressors including a change in nutrition, environmental change, transport and painful husbandry procedures (castration, dehorning). The reduction of the cumulative effects of these multiple stressors around the time of weaning together with vaccination programmes (preconditioning) can reduce subsequent morbidity and mortality in the feedlot. In most studies, calves housed individually and calves housed outdoors with shelter, are associated with decreased risk of disease. Even though it poses greater management challenges, successful group housing of calves is possible. Special emphasis should be given to equal age groups and to keeping groups stable once they are formed. The management of pneumonia in calves is reliant on a sound understanding of aetiology, relevant risk factors, and of effective approaches to diagnosis and treatment. Early signs of pneumonia include increased respiratory rate and fever, followed by depression. The single most important factor determining the success of therapy in calves with pneumonia is early onset of treatment, and subsequent adequate duration of treatment. The efficacy and economical viability of vaccination against respiratory disease in calves remains unclear