National resident survey in dermatopathology: The role of slide scanners in resident learning.

BACKGROUND: Dermatology residents gain exposure to dermatopathology through a variety of educational modalities. While virtual pathology applications have risen dramatically, resident utilization of digital libraries, slide scanner availability, and comfort with virtual slides are not well-known. This study aims to assess the current landscape of educational resources used by dermatology residents. METHODS: A 17-question survey was sent to dermatology residents through a national email database. The survey was a self-assessment of their experience in dermatopathology education and the use of departmental slide scanners. RESULTS: The use of digital dermatopathology is high among trainees, despite only half of respondents reporting slide scanner access. Residents report using virtual images more often in non-clinical dermatopathology didactics and independent studies compared to clinical dermatopathology rotations. Public slide set use was common, while professional society and departmental slide sets may be underutilized. Over half of respondents report being extremely or very comfortable navigating interactive scanned slides. CONCLUSIONS: Survey data suggests digital slides are currently predominantly used in non-clinical dermatopathology rotations and independent studies. Incorporation of slide scanners into departments may benefit resident education through the development of high-quality, curated departmental slide sets.

Control of Diabetic Gustatory Hyperhidrosis With Topical 20% Aluminum Chloride Hexahydrate.

Diabetic gustatory hyperhidrosis is a late sequela of diabetes and can have profound consequences. We report a case of diabetic gustatory hyperhidrosis controlled with topical aluminum chloride hexahydrate and support this as a first-line treatment. Aluminum chloride hexahydrate is a safe, effective, inexpensive and commercially available treatment.

Snagfall the first decade after severe bark beetle infestation of high-elevation forests in Colorado, USA.

The persistence and fall rate of snags (standing dead trees) generated during bark beetle outbreaks have consequences for the behavior, effects, and suppression of potential wildfires, hazard tree and timber salvage operations, wildlife habitat, and numerous ecosystem processes. However, post-beetle snagfall dynamics are poorly understood in most forest types. We tagged standing live and dead lodgepole pine (Pinus contorta), subalpine fir (Abies lasiocarpa), and Engelmann spruce (Picea engelmannii), including beetle-killed pine snags following the peak of a recent mountain pine bark beetle outbreak in watersheds at the Fraser Experimental Forest in northcentral Colorado and sampled snagfall 10 and 12 years later. Bark beetle attacks began in 2003, peaked by 2006, and killed 78% of overstory lodgepole pine in 133 plots distributed across a range of stand and site conditions. Of those snags, only 17% fell between 2007 and 2018. Most snags broke at ground level, due to butt rot, and were oriented downhill. In contrast, snags that tipped up or snapped off above the ground were oriented with the prevailing winds. Equal numbers of snags fell singly and in multiple-tree groups, and equal numbers remained elevated rather than in contact with the ground. Lodgepole pine snagfall was 1.6-times higher on steep slopes (>40%) where dead pine density was higher, compared to flatter sites. Based on our findings and previous research, we estimate that one-half the beetle-killed lodgepole pine in high-elevation forests such as those at Fraser may fall within 15-20 yr of beetle infestation, but that some pine snags are likely to persist for decades longer. Post-outbreak snagfall dynamics create a multiple-decade legacy of bark beetle outbreaks that will persist longer in high-elevation compared to lower-elevation forests.

Cutaneous intestinal metaplasia: An unusual cause of peristomal complication with malignant potential.

Peristomal ulcer with cutaneous intestinal metaplasia, defined by scattered colonic crypts within variably intact epidermis, is an exceedingly rare pathologic diagnosis, which possesses the potential to progress to primary adenocarcinoma. Herein, we report the third case of cutaneous intestinal metaplasia in a peristomal ulcer and emphasize the importance of diagnosis and surveillance when managing this rare entity.

Creation and Preliminary Characterization of Pregnane X Receptor and Constitutive Androstane Receptor Knockout Rats.

The nuclear receptors pregnane X receptor (PXR) and constitutive androstane receptor (CAR) are closely related transcription factors that regulate the expression of phase I (cytochrome P450s) and phase II metabolizing enzymes and transporter genes in response to stimulation from xenobiotics, including prescription drugs. PXR and CAR knockout and humanized mouse models have proven useful. However, the rat being bigger in size is a preferred model system for studying drug metabolism and pharmacokinetics. Here, we report the creation and preliminary characterization of PXR and CAR knockout rats and PXR/CAR double knockout rats. Whereas the expression of phase I and II enzymes and transporter genes were not upregulated by nuclear receptor-specific agonists pregnenlone-16α-carbonitrile and 1,4-bis-[2-(3,5-dichloropyridyloxy)] benzene in the knockout rats, confirming the disruption of respective nuclear receptor(s), our data demonstrate that PXR appears to suppress the basal expression levels of Cyp2b2, Cyp3a23/3a1, Cyp3a2, Cyp3a18, and Ugt2b1 genes, while CAR maintains Cyp2b2 and Ugt2b1 and suppresses Cyp3a9 basal expression levels. In wild-type rats, agonist binding of the nuclear receptors relieves the suppression, and target genes are expressed at levels comparable to knockout rats, with or without drug treatment. Overall, our findings are in good agreement with data obtained from human primary hepatocytes, nuclear receptor knockout cell lines, and mouse knockout models. We believe these models are a useful complement to their mouse counterparts for drug development and as importantly, for functional studies on metabolic pathways involving nuclear receptors.

Landscape variation in tree regeneration and snag fall drive fuel loads in 24-year old post-fire lodgepole pine forests.

Escalating wildfire in subalpine forests with stand-replacing fire regimes is increasing the extent of early-seral forests throughout the western USA. Post-fire succession generates the fuel for future fires, but little is known about fuel loads and their variability in young post-fire stands. We sampled fuel profiles in 24-year-old post-fire lodgepole pine (Pinus contorta var. latifolia) stands (n = 82) that regenerated from the 1988 Yellowstone Fires to answer three questions. (1) How do canopy and surface fuel loads vary within and among young lodgepole pine stands? (2) How do canopy and surface fuels vary with pre- and post-fire lodgepole pine stand structure and environmental conditions? (3) How have surface fuels changed between eight and 24 years post-fire? Fuel complexes varied tremendously across the landscape despite having regenerated from the same fires. Available canopy fuel loads and canopy bulk density averaged 8.5 Mg/ha (range 0.0-46.6) and 0.24 kg/m3 (range: 0.0-2.3), respectively, meeting or exceeding levels in mature lodgepole pine forests. Total surface-fuel loads averaged 123 Mg/ha (range: 43-207), and 88% was in the 1,000-h fuel class. Litter, 1-h, and 10-h surface fuel loads were lower than reported for mature lodgepole pine forests, and 1,000-h fuel loads were similar or greater. Among-plot variation was greater in canopy fuels than surface fuels, and within-plot variation was greater than among-plot variation for nearly all fuels. Post-fire lodgepole pine density was the strongest positive predictor of canopy and fine surface fuel loads. Pre-fire successional stage was the best predictor of 100-h and 1,000-h fuel loads in the post-fire stands and strongly influenced the size and proportion of sound logs (greater when late successional stands had burned) and rotten logs (greater when early successional stands had burned). Our data suggest that 76% of the young post-fire lodgepole pine forests have 1,000-h fuel loads that exceed levels associated with high-severity surface fire potential, and 63% exceed levels associated with active crown fire potential. Fire rotations in Yellowstone National Park are predicted to shorten to a few decades and this prediction cannot be ruled out by a lack of fuels to carry repeated fires.

Twenty-four years after theYellowstone Fires: Are postfire lodgepole pine stands converging in structure and function?

Disturbance and succession have long been of interest in ecology, but how landscape patterns of ecosystem structure and function evolve following large disturbances is poorly understood. After nearly 25 years, lodgepole pine (Pinus contorta var. latifolia) forests that regenerated after the 1988 Yellowstone Fires (Wyoming, USA) offer a prime opportunity to track the fate of disturbance-created heterogeneity in stand structure and function in a wilderness setting. In 2012, we resampled 72 permanent plots to ask (1) How have postfire stand structure and function changed between 11 and 24 yr postfire, and what variables explain these patterns and changes? (2) How has landscape-level (among-stand) variability in postfire stand structure and function changed between 11 and 24 yr postfire? We expected to see evidence of convergence beginning to emerge, but also that initial postfire stem density would still determine trajectories of biomass accumulation. After 24 yr, postfire lodgepole pine density remained very high (mean = 21,738 stems/ha, range = 0-344,067 stems/ha). Stem density increased in most plots between 11 and 24 yr postfire, but declined sharply where 11-yr-postfire stem density was > 72,000 stems/ha. Stems were small in high-density stands, but stand-level lodgepole pine leaf area, foliage biomass, and live aboveground biomass increased over time and with increasing stem density. After 24 yr, mean annual lodgepole pine aboveground net primary production (ANPP) was high (mean = 5 Mg · ha⁻¹ · yr⁻¹, range = 0-16.5 Mg · ha⁻¹ · yr⁻¹). Among stands, lodgepole pine ANPP increased with stem density, which explained 69% of the variation; another 8% of the variation was explained by environmental covariates. Early patterns of postfire lodgepole pine regeneration, which were contingent on prefire serotiny and fire severity, remained the dominant driver of stand structure and function. We observed mechanisms that would lead to convergence in stem density (structure) over time, but it was landscape variation in functional variables that declined substantially. Stand structure and function have not converged across the burned landscape, but our evidence suggests function will converge sooner than structure.

Inorganic nitrogen availability after severe stand-replacing fire in the Greater Yellowstone ecosystem.

Understanding ecosystem processes as they relate to wildfire and vegetation dynamics is of growing importance as fire frequency and extent increase throughout the western United States. However, the effects of severe, stand-replacing wildfires are poorly understood. We studied inorganic nitrogen pools and mineralization rates after stand-replacing wildfires in the Greater Yellowstone Ecosystem, Wyoming. After fires that burned in summer 2000, soil ammonium concentration peaked in 2001 (33 mg NH(4)-N x kg(soil)(-1)); soil nitrate increased subsequently (2.7 mg NO(3)-N.kg(soil)(-1) in 2003) but was still low. However, annual net ammonification rates were largely negative from 2001 to 2004, indicating ammonium depletion. Thus, although net nitrification rates were positive, annual net nitrogen mineralization (net ammonification plus net nitrification) remained low. Aboveground net primary production (ANPP) increased from 0.25 to 1.6 Mg x ha(-1) x yr(-1) from 2001 to 2004, but variation in ANPP among stands was not related to net nitrogen mineralization rates. Across a broader temporal gradient (stand age zero to >250 yr), negative rates of net annual ammonification were especially pronounced in the first postfire year. Laboratory incubations using (15)N isotope pool dilution revealed that gross production of ammonium was reduced and ammonium consumption greatly exceeded gross production during the initial postfire years. Our results suggest a microbial nitrogen sink for several years after severe, stand-replacing fire, confirming earlier hypotheses about postdisturbance succession and nutrient cycling in cold, fire-dominated coniferous forests. Postfire forests in Yellowstone seem to be highly conservative for nitrogen, and microbial immobilization of ammonium plays a key role during early succession.