渭北刺槐和油松人工林林分质量初步研究

林木质量等级组成和期望成材类型的蓄积量被作为表达渭北黄土高原刺槐和油松人工林的林分质量的数量指标。结果表明，没有利用价值的林木占总林木株数的50%以上；龄级间各期望成材类型的蓄积均值趋于随着龄级的增长而增加，但波动较大，特别是在好的立地条件下生长的刺槐乔林；油松和刺槐矮林在好的立地条件下，期望成材的蓄积量高于其在并的立地条件下的值，对刺槐乔林来说则截然相反；在相同龄级内刺槐乔林的期望成材蓄积量高于刺槐矮林和油松林；由于林分间变异系数太大，因而龄级和好坏立地条件之间各期望成材类型的蓄积量差异并不显著，仅有个别龄级在好和差的立地条件下可见微小的差异；这是由无规则的抚育间代利用造成的，立地越好，采伐强度越大。     

Isolation, structure determination, and sensory activity of mouth-drying and astringent nitrogen-containing phytochemicals isolated from red currants (Ribes rubrum)

Application of chromatographic separation and taste dilution analyses recently revealed, besides a series of flavon-3-ol glycosides and (E)/(Z)-aconitic acid, four nitrogen-containing phytochemicals as the key astringent and mouth-drying compounds in red currants (Ribes rubrum). The isolation and structure determination of the astringent indoles 3-carboxymethyl-indole-1-N-beta-D-glucopyranoside (1) and 3-methylcarboxymethyl-indole-1-N-beta-D-glucopyranoside (2), as well as the astringent, noncyanogenic nitriles 2-(4-hydroxybenzoyloxymethyl)-4-beta-D-glucopyranosyloxy-2(E)-butenenitrile (3) and 2-(4-hydroxy-3-methoxybenzoyloxymethyl)-4-beta-D-glucopyranosyloxy-2(E)-butenenitrile (4) by means of 1D/2D NMR, LC-MS/MS, and UV-vis spectroscopy are reported. The structures of compounds 1 and 2 were confirmed by synthesis. Using the recently developed half-tongue test, human recognition thresholds for the astringent and mouth-drying nitrogen compounds were determined to be between 0.0003 and 5.9 micromol/L (water). In particular, the extraordinarily low threshold of 0.0003 micromol/L evaluated for the indole 1 represents the lowest recognition threshold of any astringent phytochemical reported to date.     

The avian lung-associated immune system: a review

The lung is a major target organ for numerous viral and bacterial diseases of poultry. To control this constant threat birds have developed a highly organized lung-associated immune system. In this review the basic features of this system are described and their functional properties discussed. Most prominent in the avian lung is the bronchus-associated lymphoid tissue (BALT) which is located at the junctions between the primary bronchus and the caudal secondary bronchi. BALT nodules are absent in newly hatched birds, but gradually developed into the mature structures found from 6-8 weeks onwards. They are organized into distinct B and T cell areas, frequently comprise germinal centres and are covered by a characteristic follicle-associated epithelium. The interstitial tissue of the parabronchial walls harbours large numbers of tissue macrophages and lymphocytes which are scattered throughout tissue. A striking feature of the avian lung is the low number of macrophages on the respiratory surface under non-inflammatory conditions. Stimulation of the lung by live bacteria but not by a variety of bacterial products elicits a significant efflux of activated macrophages and, depending on the pathogen, of heterophils. In addition to the cellular components humoral defence mechanisms are found on the lung surface including secretory IgA. The compartmentalisation of the immune system in the avian lung into BALT and non BALT-regions should be taken into account in studies on the host-pathogen interaction since these structures may have distinct functional properties during an immune response.     

An octahedral coordination complex of iron(VI)

The hexavalent state, considered to be the highest oxidation level accessible for iron, has previously been found only in the tetrahedral ferrate dianion, FeO4(2-). We report the photochemical synthesis of another Fe(VI) compound, an octahedrally coordinated dication bearing a terminal nitrido ligand. M?ssbauer and x-ray absorption spectra, supported by density functional theory, are consistent with the octahedral structure having an FeN triple bond of 1.57 angstroms and a singlet d2(xy) ground electronic configuration. The compound is stable at 77 kelvin and yields a high-spin Fe(III) species upon warming.     

Effect of orally administered probiotic E. coli strain Nissle 1917 on intestinal mucosal immune cells of healthy young pigs

Several beneficial effects of probiotics have been described in studies using rodent disease models and in human patients; however, the underlying mechanisms remained mostly unclear. Only a few studies focused on the effects of probiotics on the intestinal mucosal immune system. Here, we studied the effect of the probiotic strain E. coli Nissle 1917 (EcN) administered orally to young pigs at two concentrations (10(9) and 10(11)CFU/d for 21 days) on the gut-associated lymphatic tissue. This probiotic strain was shown recently to reduce recurrence of inflammation in ulcerative colitis patients. We quantified the number and distribution of intestinal immune cells (granulocytes, mast cells, CD4+, CD8+, CD25+, IgA+ lymphocytes) and the mucosal mRNA expression of cytokines (IFN-gamma, TNF-alpha, TGF-beta, IL-10) and antimicrobial peptides (PR-39, NK-lysin, prepro-defensin-beta 1, protegrins). The number and distribution of cells were highly different between small intestinal and colon segments in all groups, but were not influenced by EcN, except high dose EcN fed pigs (10(11) CFU/d) showing an increase in mucosal CD8+ cells in the ascending colon. The mRNA analysis revealed no changes associated with EcN feeding. In conclusion, according to our analyses EcN has only minor effects on the distribution of mucosal immune cells in the gut of healthy individuals. The well-established preventive effects of EcN might therefore be relate to other mechanisms than simple modulation of immune cell distribution.     

Predicting depth translocation of base cations after forest liming: results from long-term experiments

Forest liming is a common measure to counteract soil acidification. In forest practice, lime is applied to the forest floor where it changes the chemical properties. However, little is known about the depth impact of liming and the depth translocation of lime components. To investigate the long-term impact of forest liming, several study plots have been established in the 1980s in Germany in stands with different site conditions. We analysed soil chemical data obtained during the last 28?years from 45 of the study plots. We examined the depth impact of liming and predicted the main factors responsible for the increase in Calcium (Ca) and Magnesium (Mg) stocks after liming in the mineral soil using multiple linear regression analyses (MLR). Stocks of Ca and Mg as well as base saturation (BS) showed a strong depth gradient with significant differences between limed and control plots down to 40?cm of the mineral soil. About 65–70?% of applied Ca and Mg were recovered in the forest floor and the upper 40?cm of the mineral soil. BS in 0–40?cm increased by a mean of 11?%. MLR models could explain 48–74?% of the variation in mean changes of Ca and Mg in 0–10, 10–20 and 20–40?cm soil depth when soil and climate variables, amount of applied lime and years after liming are included in the model. After testing the model robustness with a cross-validating procedure, we concluded that these models might be applied to many regions in Central Europe with comparable soil and climate conditions and thus, have widespread application.     

Schmallenberg virus challenge models in cattle: infectious serum or culture-grown virus?

Schmallenberg virus (SBV), discovered in Europe in 2011, causes mild transient disease in adult ruminants, but fetal infection can lead to severe malformation in cattle, sheep and goats.To elucidate the pathogenesis of this novel orthobunyavirus, considerable efforts are required. A reliable and standardized infection model is essential for in vivo studies. In the present study, two groups of four cattle were inoculated with either serum passaged in cattle only or cell culture-grown virus. The replication of culture-grown SBV in cattle was reduced compared to virus inoculated via infectious serum. In a second experiment, the infectious serum was titrated in calves; the tested batch contained 10^2.83 infectious doses per mL. Hence, serum-borne virus that was only passaged in the natural host is a suitable option for a standardized SBV infection model.     

Experimental infection of South American camelids with bluetongue virus serotype 8

Bluetongue (BT) is an infectious, non-contagious disease of wild and domestic ruminants. It is caused by bluetongue virus (BTV) and transmitted by Culicoides biting midges. Since 1998, BT has been emerging throughout Europe, threatening not only the na?ve ruminant population. Historically, South American camelids (SAC) were considered to be resistant to BT disease. However, recent fatalities related to BTV in captive SAC have raised questions about their role in BTV epidemiology. Data on the susceptibility of SAC to experimental infection with BTV serotype 8 (BTV-8) were collected in an animal experiment. Three alpacas (Vicugna pacos) and three llamas (Lama glama) were experimentally infected with BTV-8. They displayed very mild clinical signs. Seroconversion was first measured 6-8 days after infection (dpi) by ELISA, and neutralising antibodies appeared 10-13 dpi. BTV-8 RNA levels in blood were very low, and quickly cleared after seroconversion. However, spleens collected post-mortem were still positive for BTV RNA, over 71 days after the last detection in blood samples. Virus isolation was only possible from blood samples of two alpacas by inoculation of highly sensitive interferon alpha/beta receptor-deficient (IFNAR(-/-)) mice. An in vitro experiment demonstrated that significantly lower amounts of BTV-8 adsorb to SAC blood cells than to bovine blood cells. Although this experiment showed that SAC are generally susceptible to a BTV-8 infection, it indicates that these species play a negligible role in BTV epidemiology.     

Effects of lidocaine constant rate infusion on sevoflurane requirement, autonomic responses, and postoperative analgesia in dogs undergoing ovariectomy under opioid-based balanced anesthesia

The effects of constant rate infusion (CRI) of lidocaine on sevoflurane (SEVO) requirements, autonomic responses to noxious stimulation, and postoperative pain relief were evaluated in dogs undergoing opioid-based balanced anesthesia. Twenty-four dogs scheduled for elective ovariectomy were randomly assigned to one of four groups: BC, receiving buprenorphine without lidocaine; FC, receiving fentanyl without lidocaine; BL, receiving buprenorphine and lidocaine; FL, receiving fentanyl and lidocaine. Dogs were anesthetized with intravenous (IV) diazepam and ketamine and anesthesia maintained with SEVO in oxygen/air. Lidocaine (2mg/kg plus 50μg/kg/min) or saline were infused in groups BL/FL and BC/FC, respectively. After initiation of lidocaine or saline CRI IV buprenorphine (0.02mg/kg) or fentanyl (4μg/kg plus 8μg/kg/h CRI) were administered IV in BC/BL and FC/FL, respectively. Respiratory and hemodynamic variables, drug plasma concentrations, and end-tidal SEVO concentrations (E'SEVO) were measured. Behaviors and pain scores were subjectively assessed 1 and 2h post-extubation. Lidocaine CRI produced median drug plasma concentrations <0.4μg/mL during peak surgical stimulation. Lidocaine produced a 14% decrease in E'SEVO in the BL (P<0.01) but none in the FL group and no change in cardio-pulmonary responses to surgery or postoperative behaviors and pain scores in any group. Thus, depending on the opioid used, supplementing opioid-based balanced anesthesia with lidocaine (50μg/kg/min) may not have any or only a minor impact on anesthetic outcome in terms of total anesthetic dose, autonomic responses to visceral nociception, and postoperative analgesia.