Caries Presentation in Illict Drug Users and Excessive Soft Drink Consumers.

PosterAdvanced cervical caries in anterior teeth is common to two different patient behaviors. Rampant cervical caries (“meth mouth”) is a common presentation in drug users. Extensive consumption of soft drinks also presents a similar pattern of cervical caries. Two cases are presented and dental treatment considerations are discussed. Case One: excessive soft drink consumption. A young male presented to IUSD for evaluation and treatment of a painful #9. Clinical exam: #9 had extensive facial and cervical caries with a pulp exposure. Cervical caries on teeth #6, 7,8,10,11,12,13. Patient’s history revealed frequent daily consumption of multiple sweet soft drinks. #9 had become increasingly painful and that caused him to seek treatment. Pulpal and Percussion/Palpation testing and radiographic exam of #9 were conducted. Diagnosis: #9 Pulpal Necrosis with Symptomatic Apical Periodontitis. Treatment: Oral hygiene instruction to reduce the frequency of soft drink consumption. #9 was endodontically treated and restored. Caries in #6, 7,8,10,11,12,13 were treated and teeth restored. Case Two: cocaine abuse. A young female presented to IUSD for evaluation and treatment of a painful #9. Clinical exam: #9 had extensive cervical caries. Cervical caries on #7, 8, 9 and dental attrition. Patient reports having used cocaine for many years. Pulpal and Percussion/Palpation testing and radiographic exam of #9 were conducted. Diagnosis: #9 Pulpal Necrosis with Symptomatic Apical Periodontitis. Treatment considerations: Local anesthesia was achieved without the use of epinephrine due to possible occasional unreported use of cocaine. #9 was endodontically treated and restored. Patient did not return for continued treatment at IUSD. Conclusion: Cervical caries in anterior teeth associated with soft drinks demonstrate similar characteristics to those observed in patients with reported cocaine abuse. This should alert dental providers dentists to be aware of both illicit drug use and soft drink intake as part of the patient’s medical, dental, and social history information

Ecotypic differences in the phenology of the tundra species Eriophorum vaginatum reflect sites of origin

Eriophorum vaginatum is a tussock-forming sedge that contributes significantly to the structure and primary productivity of moist acidic tussock tundra. Locally adapted populations (ecotypes) have been identified across the geographical distribution of E. vaginatum; however, little is known about how their growth and phenology differ over the course of a growing season. The growing season is short in the Arctic and therefore exerts a strong selection pressure on tundra species. This raises the hypothesis that the phenology of arctic species may be poorly adapted if the timing and length of the growing season change. Mature E. vaginatum tussocks from across a latitudinal gradient (65–70°N) were transplanted into a common garden at a central location (Toolik Lake, 68°38′N, 149°36′W) where half were warmed using open-top chambers. Over two growing seasons (2015 and 2016), leaf length was measured weekly to track growth rates, timing of senescence, and biomass accumulation. Growth rates were similar across ecotypes and between years and were not affected by warming. However, southern populations accumulated significantly more biomass, largely because they started to senesce later. In 2016, peak biomass and senescence of most populations occurred later than in 2015, probably induced by colder weather at the beginning of the growing season in 2016, which caused a delayed start to growth. The finish was delayed as well. Differences in phenology between populations were largely retained between years, suggesting that the amount of time that these ecotypes grow has been selected by the length of the growing seasons at their respective home sites. As potential growing seasons lengthen, E. vaginatum may be unable to respond appropriately as a result of genetic control and may have reduced fitness in the rapidly warming Arctic tundra

Differential responses of ecotypes to climate in a ubiquitous arctic sedge: implications for future ecosystem C cycling

The response of vegetation to climate change has implications for the carbon cycle and global climate. It is frequently assumed that a species responds uniformly across its range to climate change. However, ecotypes—locally adapted populations within a species—display differences in traits, which may affect their gross primary productivity (GPP) and response to climate change. To determine if ecotypes are important for understanding the response of ecosystem productivity to climate we measured and modeled growing season GPP in reciprocally transplanted and experimentally warmed ecotypes of the abundant arctic sedge Eriophorum vaginatum. Transplanted northern ecotypes displayed home site advantage in GPP that was associated with differences in leaf area index. Southern ecotypes exhibited a greater response in GPP when transplanted. The results demonstrate that ecotypic differentiation can impact the morphology and function of vegetation with implications for carbon cycling. Moreover they suggest that ecotypic control of GPP may limit the response of ecosystem productivity to climate change. This investigation shows that ecotypes play a substantial role in determining GPP and its response to climate. These results have implications for understanding annual to decadal carbon cycling where ecotypes could influence ecosystem function and vegetation feedbacks to climate change

Interspecific and intraspecific variation in leaf toughness of Arctic plants in relation to habitat and nutrient supply

Leaf toughness is an important functional trait that confers resistance to herbivory and mechanical damage. We sought to determine how species composition, climate, seasonality, and nutrient availability influence leaf toughness in two types of tundra in northern Alaska. We measured leaf toughness as force to punch for 11 species of Arctic plants in tussock tundra and dry heath tundra at 17 sites distributed along a latitudinal gradient. Rubus chamaemorus and the graminoids occupied opposite ends of the leaf toughness spectrum, with R. chamaemorus requiring the least force to punch, while one of the graminoids, Eriophorum vaginatum, required the most. Leaf toughness increased with mean summer temperature for E. vaginatum and Betula nana, while it declined with warmer temperatures for the other species. Toughness of mature leaves of E. vaginatum did not vary through the growing season but declined significantly after senescence. Application of N and P fertilizer in an experimental site decreased leaf toughness in three species but had no effect on four others. Leaf toughness of four out of five species in dry heath was greater than for the same species in tussock tundra, but there was no difference in community-weighted mean toughness between tussock tundra and dry heath.Output Status: Forthcoming/Available Onlin

Intra-specific variation in phenology offers resilience to climate change for Eriophorum vaginatum

Phenology of arctic plants is an important determinant of the pattern of carbon uptake and may be highly sensitive to continued rapid climate change. Eriophorum vaginatum has a disproportionate influence over ecosystem processes in moist acidic tundra, but it is unclear whether its growth and phenology will remain competitive in the future. We asked whether northern tundra ecotypes of E. vaginatum could extend their growing season in response to direct warming and transplanting into southern ecosystems. At the same time, we asked whether southern ecotypes could adjust their growth patterns in order to thrive further north, should they disperse quickly enough. Detailed phenology measurements across three reciprocal transplant gardens and two years showed that some northern ecotypes were capable of growing for longer when conditions were favourable, but their biomass and growing season length was still shorter than the southern ecotype. Southern ecotypes retained large leaf length when transplanted north and mirrored the growing season length better than the others, mainly due to immediate green-up after snowmelt. All ecotypes retained the same senescence timing, regardless of environment, indicating a strong genetic control. E. vaginatum may remain competitive in a warming world if southern ecotypes can migrate north.Output Status: Forthcoming/Available Onlin

Crystal structure of rhodopsin bound to arrestin by femtosecond X-ray laser.

G-protein-coupled receptors (GPCRs) signal primarily through G proteins or arrestins. Arrestin binding to GPCRs blocks G protein interaction and redirects signalling to numerous G-protein-independent pathways. Here we report the crystal structure of a constitutively active form of human rhodopsin bound to a pre-activated form of the mouse visual arrestin, determined by serial femtosecond X-ray laser crystallography. Together with extensive biochemical and mutagenesis data, the structure reveals an overall architecture of the rhodopsin-arrestin assembly in which rhodopsin uses distinct structural elements, including transmembrane helix 7 and helix 8, to recruit arrestin. Correspondingly, arrestin adopts the pre-activated conformation, with a ∼20° rotation between the amino and carboxy domains, which opens up a cleft in arrestin to accommodate a short helix formed by the second intracellular loop of rhodopsin. This structure provides a basis for understanding GPCR-mediated arrestin-biased signalling and demonstrates the power of X-ray lasers for advancing the frontiers of structural biology

Caries Presentation in Illict Drug Users and Excessive Soft Drink Consumers.

PosterAdvanced cervical caries in anterior teeth is common to two different patient behaviors. Rampant cervical caries (“meth mouth”) is a common presentation in drug users. Extensive consumption of soft drinks also presents a similar pattern of cervical caries. Two cases are presented and dental treatment considerations are discussed. Case One: excessive soft drink consumption. A young male presented to IUSD for evaluation and treatment of a painful #9. Clinical exam: #9 had extensive facial and cervical caries with a pulp exposure. Cervical caries on teeth #6, 7,8,10,11,12,13. Patient’s history revealed frequent daily consumption of multiple sweet soft drinks. #9 had become increasingly painful and that caused him to seek treatment. Pulpal and Percussion/Palpation testing and radiographic exam of #9 were conducted. Diagnosis: #9 Pulpal Necrosis with Symptomatic Apical Periodontitis. Treatment: Oral hygiene instruction to reduce the frequency of soft drink consumption. #9 was endodontically treated and restored. Caries in #6, 7,8,10,11,12,13 were treated and teeth restored. Case Two: cocaine abuse. A young female presented to IUSD for evaluation and treatment of a painful #9. Clinical exam: #9 had extensive cervical caries. Cervical caries on #7, 8, 9 and dental attrition. Patient reports having used cocaine for many years. Pulpal and Percussion/Palpation testing and radiographic exam of #9 were conducted. Diagnosis: #9 Pulpal Necrosis with Symptomatic Apical Periodontitis. Treatment considerations: Local anesthesia was achieved without the use of epinephrine due to possible occasional unreported use of cocaine. #9 was endodontically treated and restored. Patient did not return for continued treatment at IUSD. Conclusion: Cervical caries in anterior teeth associated with soft drinks demonstrate similar characteristics to those observed in patients with reported cocaine abuse. This should alert dental providers dentists to be aware of both illicit drug use and soft drink intake as part of the patient’s medical, dental, and social history information

Data from: Biogenic silica accumulation varies across tussock tundra plant functional type

1. Silica (SiO2) accumulation by terrestrial vegetation is an important component of the biological silica cycle because it improves overall plant fitness and influences export rates of silica from terrestrial to marine systems. However, most research on silica in plants has focused on agricultural and forested ecosystems, and knowledge of terrestrial silica cycling in the Arctic, as well as the potential impacts of climate change on the silica cycle is severely lacking. 2. We quantified biogenic silica (BSi) accumulation in above and belowground portions of three moist acidic tundra (MAT) sites spanning a 300 km latitudinal gradient in central and northern Alaska, USA. We also examined plant silica accumulation across three main tundra types found in the Arctic (MAT, moist non-acidic tundra (MNT), and wet sedge tundra (WST)). 3. BSi concentrations in live Eriophorum vaginatum, a tussock-forming sedge that is the foundation species of tussock tundra, were not significantly (p<0.05) different across the three main sites. Concentrations of BSi in live aboveground tissue were highest in the graminoid species (0.55 ± 0.07 % BSi in sedges from WST, and 0.27 ± 0.01% in E. vaginatum across the three MAT sites). Both inter-tussock tundra species and shrubs contained substantially lower BSi concentrations than E. vaginatum. 4. Our results have implications for how shifts in vegetation cover associated with climatic warming may alter silica storage in tussock tundra vegetation. Our calculations suggest that shrub expansion via warming will increase BSi storage in Arctic land plants due to the higher biomass associated with shrub tundra, whereas conversion of tussock tundra to WST via permafrost thaw would produce the opposite effect in the terrestrial plant BSi pool. Such changes in the size of the terrestrial vegetation silica reservoir could have direct consequences for the rates and timing of silica delivery to receiving waters in the Arctic