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1.
A modification of the method of Lewis and Jones clearly and selectively demonstrates elastin, reticulum, and collagen in the same section. The technique combines ammoniacal silver carbonate, orcein in acid alcohol, and aniline blue following phosphomolybdic acid. Vascular invasion and capsular infiltration caused by carcinoma and degenerative diseases of connective tissues and blood vessels are shown very clearly. Diagnosis is thus facilitated in both surgical and postmortem pathology. 相似文献
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We tested the hypothesis that development of the Antarctic urchin Sterechinus neumayeri under future ocean conditions of warming and acidification would incur physiological costs, reducing the tolerance of a secondary stressor. The aim of this study is twofold: (1) quantify current austral spring temperature and pH near sea urchin habitat at Cape Evans in McMurdo Sound, Antarctica and (2) spawn S. neumayeri in the laboratory and raise early developmental stages (EDSs) under ambient (?0.7 °C; 400 µatm pCO2) and future (+2.6 °C; 650 and 1,000 µatm pCO2) ocean conditions and expose four EDSs (blastula, gastrula, prism, and 4-arm echinopluteus) to a one hour acute heat stress and assess survivorship. Results of field data from 2011 to 2012 show extremely stable inter-annual pH conditions ranging from 7.99 to 8.08, suggesting that future ocean acidification will drastically alter the pH-seascape for S. neumayeri. In the laboratory, S. neumayeri EDSs appear to be tolerant of temperatures and pCO2 levels above their current habitat conditions. EDSs survived acute heat exposures >20 °C above habitat temperatures of ?1.9 °C. No pCO2 effect was observed for EDSs reared at ?0.7 °C. When reared at +2.6 °C, small but significant pCO2 effects were observed at the blastula and prism stage, suggesting that multiple stressors are more detrimental than single stressors. While surprisingly tolerant overall, blastulae were the most sensitive stage to ocean warming and acidification. We conclude that S. neumayeri may be unexpectedly physiologically tolerant of future ocean conditions. 相似文献
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Daniel J. Norton Victoria A. Nguyen Michaela F. Lewis Gretchen O. Reynolds David C. Somers Alice Cronin-Golomb 《PloS one》2016,11(3)
Parkinson’s disease (PD) is associated with deficits in visuospatial attention. It is as yet unknown whether these attentional deficits begin at a perceptual level or instead reflect disruptions in oculomotor or higher-order processes. In the present study, non-demented individuals with PD and matched normal control adults (NC) participated in two tasks requiring sustained visuospatial attention, both based on a multiple object tracking paradigm. Eye tracking was used to ensure central fixation. In Experiment 1 (26 PD, 21 NC), a pair of identical red dots (one target, one distractor) rotated randomly for three seconds at varied speeds. The task was to maintain the identity of the sole target, which was labeled prior to each trial. PD were less accurate than NC overall (p = .049). When considering only trials where fixation was maintained, however, there was no significant group difference, suggesting that the deficit’s origin is closely related to oculomotor processing. To determine whether PD had additional impairment in multifocal attention, in Experiment 2 (25 PD, 15 NC), two targets were presented along with distractors at a moderate speed, along with a control condition in which dots remained stationary. PD were less accurate than NC for moving (p = 0.02) but not stationary targets. This group difference remained significant when considering only trials where fixation was maintained, suggesting the source of the PD deficit was independent from oculomotor processing. Taken together, the results implicate separate mechanisms for single vs. multiple object tracking deficits in PD. 相似文献
8.
Bielmyer GK Gatlin D Isely JJ Tomasso J Klaine SJ 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2005,140(1):131-137
Mechanisms of copper toxicity and consequences of exposure vary due to uptake route and ionoregulatory status. The goal of this research was to develop a model fish system to assess the influence of different Cu exposure routes (waterborne or dietary) on bioavailability, uptake, and effects in hybrid striped bass (Morone chrysops x Morone saxatilis) acclimated to fresh- or saltwater. Initially, hybrid striped bass were exposed to dietary Cu concentrations of 571, 785, and 1013 mug Cu/g, along with a control (approximately 5 microg Cu/g), for 14 days in saltwater. Intestinal and liver Cu accumulated in a dose-dependent manner in fish exposed to increasing levels of dietary Cu. Chronic (42 days) experiments were then conducted to determine sub-lethal effects of aqueous, dietary, and combined aqueous and dietary Cu exposures to both freshwater- and saltwater-acclimated hybrid striped bass. Growth and Cu accumulation in the gill, intestine, and liver were measured. Although no significant effects were observed in fish exposed to waterborne Cu, those exposed through the diet accumulated significant liver and intestinal Cu but showed no significant change in growth. Overall, these results suggest that at the levels tested, exposure to elevated waterborne Cu did not cause significant long-term tissue Cu accumulation, whereas dietary Cu exposure caused significant liver and intestinal Cu accumulation in hybrid striped bass which was comparable in both freshwater and saltwater (15 g/L). 相似文献
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Angel M. Padilla Phil Y. Yao Tre J. Landry Gretchen M. Cooley Susan M. Mahaney Isabela Ribeiro John L. VandeBerg Rick L. Tarleton 《PLoS neglected tropical diseases》2021,15(3)
Trypanosoma cruzi, the causative agent of human Chagas disease, is endemic to the southern region of the United States where it routinely infects many host species. The indoor/outdoor housing configuration used in many non-human primate research and breeding facilities in the southern of the USA provides the opportunity for infection by T. cruzi and thus provides source material for in-depth investigation of host and parasite dynamics in a natural host species under highly controlled and restricted conditions. For cynomolgus macaques housed at such a facility, we used a combination of serial blood quantitative PCR (qPCR) and hemoculture to confirm infection in >92% of seropositive animals, although each method alone failed to detect infection in >20% of cases. Parasite isolates obtained from 43 of the 64 seropositive macaques were of 2 broad genetic types (discrete typing units, (DTU’s) I and IV); both within and between these DTU groupings, isolates displayed a wide variation in growth characteristics and virulence, elicited host immune responses, and susceptibility to drug treatment in a mouse model. Likewise, the macaques displayed a diversity in T cell and antibody response profiles that rarely correlated with parasite DTU type, minimum length of infection, or age of the primate. This study reveals the complexity of infection dynamics, parasite phenotypes, and immune response patterns that can occur in a primate group, despite being housed in a uniform environment at a single location, and the limited time period over which the T. cruzi infections were established. 相似文献
10.
Widespread invasion of riparian ecosystems by the large bamboo-like grass Arundo donax L. has altered community structure and ecological function of streams in California. This study evaluated the influence of
wildfire on A. donax invasion by investigating its relative rate of reestablishment versus native riparian species after wildfire burned 300 ha
of riparian woodlands along the Santa Clara River in southern California in October 2003. Post-fire A. donax growth rates and productivity were compared to those of native woody riparian species in plots established before and after
the fire. Arundo donax resprouted within days after the fire and exhibited higher growth rates and productivity compared to native riparian plants.
Arundo donax grew 3–4 times faster than native woody riparian plants—up to a mean of 2.62 cm day−1—and reached up to 2.3 m in height less than 3 months after the fire. One year post-fire, A. donax density was nearly 20 times higher and productivity was 14–24 times higher than for native woody species. Three mechanisms—fire-adapted
phenology, high growth rate, and growth response to nutrient enrichment—appear to promote the preemption of native woody riparian
species by A. donax after fire. This greater dominance of A. donax after wildfire increased the susceptibility of riparian woodlands along the Santa Clara River to subsequent fire, potentially
creating an invasive plant-fire regime cycle. Moreover, A. donax infestations appear to have allowed the wildfire to cross the broad bed of the Santa Clara River from the north, allowing
thousands of acres of shrubland to the south to burn. 相似文献