Homogeneity of Trypanosoma cruzi I, II, and III populations and the overlap of wild and domestic transmission cycles by Triatoma brasiliensis in northeastern Brazil

The genetic variability of 24 Trypanosoma cruzi isolates from humans (11) and triatomines (13) in northeastern Brazil was analyzed by random amplified polymorphic DNA (RAPD) and compared with taxonomic groups, host, and geographical origin of the parasite. TcI (12.5 %), TcII (45.8 %), and TcIII (41.6 %) showed a similarity coefficient (SC) of 0.74 using the mean of three primers and 0.80, 0.75, and 0.66 for λgt11-F, M13-40F, and L15996 primers, respectively. The samples were clustered according to their phylogenetic origin in two polymorphic and divergent branches: one associated with TcI and the other with two subbranches corresponding to TcII and TcIII. TcI was only identified in humans and correlated with the Id homogenous group (0.80 SC). TcII from humans and Triatoma brasiliensis showed 0.86 SC and was clustered according monoclonal or polyclonal populations with similar RAPD profiles detected among the vector and/or humans in different municipalities. TcIII was isolated exclusively in sylvatic cycles from T. brasiliensis and Panstrongylus lutzi and showed low variability (0.84 SC) and high homology mainly among isolated populations at the same locality. The homology of T. cruzi among different hosts and locations suggests the distribution of principal clones circulating and reveals an overlapping between the sylvatic and domestic cycles in this area, where T. brasiliensis infected with TcII acts as link in both environments. This species is important to maintain TcII and TcIII in wild cycles and deserves particular attention due an emergent risk of these populations being introduced into the domestic cycle; moreover, its clinical and epidemiological implications remain unknown.     

2-Methacryloyloxyethyl phosphorylcholine (MPC)-polymer suppresses an increase of oral bacteria: a single-blind,crossover clinical trial

Clinical Oral Investigations - The biocompatible 2-methacryloyloxyethyl phosphorylcholine (MPC)-polymers, which mimic a biomembrane, reduce protein adsorption and bacterial adhesion and inhibit...     

Serum soluble CD163 levels in patients with influenza-associated encephalopathy

Background: Influenza-associated encephalopathy (IE) is a serious complication during influenza viral infection. Common clinical symptoms of IE include seizures and progressive coma with high-grade fever. We previously reported that hypercytokinemia and monocyte/macrophage activation may play an important role in the pathogenesis of IE. CD163 is a scavenger receptor for hemoglobin–haptoglobin complexes and is expressed by monocytes/macrophages. Proteolytic cleavage of monocyte-bound CD163 by matrix metalloproteinases releases soluble CD163 (sCD163). However, there have been no reports regarding serum sCD163 levels in IE patients. Methods: We measured serum levels of sCD163 as a marker of monocyte/macrophage activation in IE patients with poor outcomes, those without neurological sequelae, influenza patients without IE, and control subjects. Results: Serum sCD163 levels were significantly higher in IE patients with poor outcomes than in those without neurological sequelae. In particular, sCD163 levels in cases of death were significantly higher than those in other cases. Conclusions: Our results suggest that monocyte/macrophage activation is related to the pathogenesis of severe IE.     

Chloroquine-induced hyperpigmentation of the hard palate

This article reports a rare case of extensive palatal pigmentation secondary to long-term chloroquine treatment. Chloroquine was originally used as an antimalarial agent, but it is now widely used as an adjunct in the treatment of autoimmune diseases. Adverse effects of chloroquine usually include skin changes such as bullous pemphigoid, exacerbation of psoriasis, and pigmentation of the skin and mucous membranes as well as retinopathy, gastrointestinal alterations, and neuromuscular disorders. Extensive oral pigmentation is an uncommon feature of an adverse drug effect, and diagnosis should be based on clinicopathological findings.     

A bottom-up control on fresh-bedrock topography under landscapes

The depth to unweathered bedrock beneath landscapes influences subsurface runoff paths, erosional processes, moisture availability to biota, and water flux to the atmosphere. Here we propose a quantitative model to predict the vertical extent of weathered rock underlying soil-mantled hillslopes. We hypothesize that once fresh bedrock, saturated with nearly stagnant fluid, is advected into the near surface through uplift and erosion, channel incision produces a lateral head gradient within the fresh bedrock inducing drainage toward the channel. Drainage of the fresh bedrock causes weathering through drying and permits the introduction of atmospheric and biotically controlled acids and oxidants such that the boundary between weathered and unweathered bedrock is set by the uppermost elevation of undrained fresh bedrock, Z_b. The slow drainage of fresh bedrock exerts a “bottom up” control on the advance of the weathering front. The thickness of the weathered zone is calculated as the difference between the predicted topographic surface profile (driven by erosion) and the predicted groundwater profile (driven by drainage of fresh bedrock). For the steady-state, soil-mantled case, a coupled analytical solution arises in which both profiles are driven by channel incision. The model predicts a thickening of the weathered zone upslope and, consequently, a progressive upslope increase in the residence time of bedrock in the weathered zone. Two nondimensional numbers corresponding to the mean hillslope gradient and mean groundwater-table gradient emerge and their ratio defines the proportion of the hillslope relief that is unweathered. Field data from three field sites are consistent with model predictions.Uplift and erosion of bedrock commonly leads to ridge and valley topography variably mantled with weathered bedrock and soil. Quasi-steady-state conditions may develop in which the topography is statistically constant as channels incise, hillslope surfaces erode, and fresh bedrock is uplifted to the surface. As this fresh bedrock rises up, it enters a near-surface zone where weathering irreversibly breaks and alters the rock before it is entrained into the mobile soil mantle and transported to adjacent streams. Variably weathered bedrock occupies the zone between the top of the fresh bedrock and the bottom of the soil. Here we identify Z_b as the elevation of the transition from fresh to weathered bedrock (Fig. 1).Open in a separate windowFig. 1.Conceptual model showing the elevation of fresh bedrock, Z_b, under ridge and valley topography with a thin soil mantle overlying a weathered bedrock zone that extends to Z_b. Channel incision, at the rate C_o, drives hillslope erosion and drainage of fresh bedrock (flow paths illustrated with blue arrows). (Left) The model framework and assumptions. At the ridgetop (x = 0), the surface elevation is Z_s0 and the fresh-bedrock elevation is Z_b0. Groundwater flux, q_w, is horizontal and proportional to the water table gradient, Z_b. Soil transport, q_s, is proportional to the surface slope, Z_s. All soil and water leaves the hillslope at L where the hillslope meets the channel. At steady state, the rate of channel incision (C_o) is equal to the uplift rate such that the ground surface, Z_s and surface of the fresh bedrock, Z_b, are stationary.The transport of sediment and water from hillslopes to stream channels is influenced by the rock property changes that result from weathering. Hence, the depth to and topography of Z_b is an important driver in runoff generation and landscape evolution. Weathering tends to increase bedrock hydraulic conductivity and porosity, allowing infiltrating waters to perch on underlying fresh bedrock and flow laterally to stream channels (Fig. 1). Field studies that have instrumented the weathered rock zone have shown that this perched groundwater path can deliver most of the stream runoff (1–4) and can be the source of sustained summer baseflow (5). The chemical evolution of hillslope runoff may be strongly dictated by the depth to Z_b and flow paths through the weathered zone (6–8). The weathering of bedrock may also increase moisture retention, which can be exploited by vegetation to sustain transpiration (9, 10). Furthermore, water exfiltration from this zone on steep slopes can cause localized elevated pore pressures and landslides (11), and the change in rock mass strength across this boundary due to weathering may localize deep-seated landslides (12, 13).Collectively, these observations suggest that, aside from the ground surface, the topography of Z_b is the most important boundary controlling surface and near-surface processes, and as such, observation and theory are needed to understand what controls its structure across a landscape. Field studies that have directly documented the depth to fresh bedrock underlying ridge and valley topography (e.g., refs. 14, 15) are rare and none have depicted the detailed 3D pattern of Z_b relative to surface topography. Nonetheless, the few studies that have mapped Z_b under hillslopes have found a tendency for the weathered zone to be thickest at the ridge top and progressively thin downslope (14–18) (as illustrated in Fig. 1). Although Pavich (15) and Feininger (18) associate this trend with areas of low relief, studies in steep landscapes in the California and Oregon Coast Ranges (5, 6) have documented a systematic upslope thickening of the weathered zone as well (Fig. S1).It is commonly assumed that the depth of weathered bedrock is controlled by downward propagating (top-down) processes driven by the advance of chemically reactive meteoric water into the underlying fresh bedrock (e.g., ref. 19). The top-down hypothesis leads to a weathered zone thickness that is set by the relative rates of erosion and the downward propagation of the weathering front. Approaches to addressing this hypothesis have included reactive transport modeling (e.g., ref. 20) and extension of the soil production function (21) to the weathered bedrock zone through a negative feedback between weathered zone thickness and erosion rate (e.g., ref. 22). For a convex 2D hillslope with a mobile weathered layer composed of soil and weathered bedrock, Lebedeva and Brantley (20) propose that the downslope steepening of the topographic surface may lead to progressively less water flux normal to the underlying reactive bedrock and, consequently, a weathered zone that thins downslope.An alternative hypothesis for the downslope decrease in depth to Z_b under hillslopes is suggested by field observations of weathering profiles. Some of the earliest quantitative observations of weathering profiles identified the role of groundwater in impeding chemical weathering, and restricting the depth of the weathered zone (e.g., refs. 14, 16, 23, 24), such as occurs in supergene enrichment processes (25). In fresh bedrock of sufficiently low hydraulic conductivity, nearly stagnant or slowly moving water will reach chemical equilibrium and chemical weathering reactions will slow or stop (19, 26). In addition, the chronic saturation of fresh bedrock prevents mechanical breakdown due to swelling and contraction cycles associated with wetting and drying (27). Drainage of this fresh bedrock permits meteoric fluids to enter from above, thus allowing atmospherically and biotically controlled acids and oxidants to enter pore spaces and induce weathering reactions.These observations suggest a “bottom up” control on the elevation of fresh bedrock under hillslopes in which drainage of saturated fresh bedrock is the key process. We propose that: (i) fresh bedrock that is advected into the near-surface environment through uplift and erosion arrives saturated with nearly stagnant pore fluid that is in chemical equilibrium with surrounding mineral surfaces; (ii) in this environment, channel incision creates a lateral head gradient in the fresh bedrock and induces drainage toward the adjacent channel; and (iii) drainage may cause drying and fracturing of the bedrock and permit meteoric water to enter the fresh bedrock, inducing weathering at the rate that the fresh bedrock is drained. For these conditions, we propose that the fresh-bedrock drainage profile defines Z_b. The depth of fresh bedrock along a hillslope will depend on both this groundwater-drainage control and on the erosion shaping the surface topography. Here we predict the thickness of the weathered bedrock zone by coupling a groundwater flow model with a surface erosion model.     

Inferior Alveolar Neurosensory Deficiency Associated With Placement of Dental Implants

Background: This study reports and analyzes a large series of patients with neurosensory deficiency related to the placement of dental implants (DIs) and resulting in liability claims (LCs). Methods: From 1998 to 2009, there were 92 LCs related to persistent altered sensation post DI placements in Israel. Patients’ demographics, year and source of LCs, interval between the procedure that resulted in a neurosensory deficiency and the LC, qualifications of the surgeon, preoperative imaging modality, DI length, available alveolar bone for DI placement, placement site, timing of DI placement (immediately after tooth extraction or after socket healing), and treatment after the diagnosis of neurosensory deficiency were recorded and analyzed. Results: There were 21 cases during the first 5 years of the study (mean 4.2/year) and 63 cases (mean 12.6/year) over the following 5 years. Thirty LCs were issued during the second postoperative year and 15 LCs after >5 years. Most LCs (76%) involved procedures that were planned and performed according to radiographs and 24% after computed tomography. Sixty‐five percent of the LCs were performed by general dental practitioners and 35% by specialists. More than one DI was performed during the surgical procedure that resulted in a neurosensory deficiency in 73 LCs (79.3%), and the DI was >10 mm in 55 (59.8%) cases. Conclusions: LCs for DIs that result in a neurosensory deficiency pose a legal risk to the practitioner long after the injury has occurred.