猫隔核微量注射异丙肾上腺素对皮质醇浓度的影响

本工作采用猫隔核微量注射β受体激动剂异丙肾上腺素(ISO)及其阻断剂心得安,了解其对血浆皮质醇浓度的影响。实验观察到:隔核微量注射ISO,可引起血浆皮质醇浓度降低;β受体阻断剂心得安有颉颃ISO降低血浆皮质醇浓度的作用;心得安阻断ISO降低血浆皮质醇的结果提示,隔核内去甲肾上腺素能神经系统可能通过β受体对肾上腺皮质分泌机能进行调制。     

A review of the bioavailability of petroleum constituents

Exposure to petroleum constituents at contaminated sites may occur through a variety of pathways, including inhalation of vapors and particulates, ingestion of water and soils, and dermal contact with water and soils. Accurately assessing the human health risks from such exposures requires information on the medium‐ and route‐specific bioavailability of petroleum constituents (e.g., how well these chemicals enter the body via the gastrointestinal tract and skin). For example, when the medium or exposure route in an animal toxicity assay (e.g., ingestion of water) differs from the actual route of human exposure at the petroleum contaminated site (e.g., dermal contact with soil), adjustments should be made that reflect the relative bioavailability of the chemical in the different media. The focus of this article is on (1) the availability of oral and dermal absorption data for one PAH (benzo[a]pyrene, (B[a]P) and three VOCs in soil (benzene, toluene, and xylene); (2) factors affecting the uptake of these PAHs and VOCs from soil; and (3) ways to incorporate bioavailability data into human health risk assessments. Based on our review, we recommend the following default values for the oral and dermal absorption of B[a]P, benzene, toluene, and xylene from soil:

A review of the bioavailability of petroleum constituents

All authors

Jennifer Bramard & Barbara D. Beck

https://doi.org/10.1080/15320389209383417

Published online:

02 December 2008

Display Table

Site‐specific information such as chemical concentrations in soil, soil characteristics, soil loadings on the skin, contact site, and contact time could result in modifications of these numbers. As shown, our default absorption values are generally less than those recommended by the U.S. EPA (1991a,b,c). The implications of these estimates of bioavailability for risk assessment and for the selection of soil cleanup levels at petroleum‐contaminated sites are discussed.     

Relationship Between Meloidogyne hapla Density and Damage to Carrots in Organic Soils

Field and growth chamber experiments were conducted to determine the effect of five initial densities (Pi - 20 - 240/100 cm³ soil) of Meloidogyne hapla on carrot development and yield of storage roots at maturity. Carrots growing in infested and noninfested organic soil were harvested after 15, 29, 44, 59, and 106 days of growth in controlled environment chambers and after l l 0 days in field plots. Nematodes affected weight of roots and foliage, weight and length of the storage portion of tap roots, and induced malformations (forking), galling, and hairiness of tap roots. In most cases the data could not be represented satisfactorily by the exponential model of Seinhorst: y = m + (l-m) Z^P-t. In growth chambers the weight of mature storage roots was not correlated to initial nematode density, but there was a significant negative correlation between weight of storage roots and initial nematode density in field plots. Tolerance levels were calculated as points where the regression lines reached the growth level on noninoculated plants. The tolerance levels of foliage were higher than those of roots, and increased with age of plants. The tolerance level of marketable weight in field plots, average crop value, and a hypothetical control cost function are used to discuss the possibility of optimizing chemical control of root-knot nematode in organic soils.     

Evaluation of chemical methods for estimating available zinc and response of green gram (Phaseolus aureus roxb) to applied zinc in non-calcareous soils

Summary Studies were conducted in 22 non-calcareous soils (India) to evaluate various extractants,viz. (6N HCl, 0.1N HCl, EDTA (NH₄)₂CO₃, EDTA NH₄OAc, DTPA+CaCl₂ and 1M MgCl₂) to find critical levels of soil and plant Zn for green gram (Phaseolus aureus Roxb.). The order of extractability by the different extractants was 6N HCl>0.1N HCl>EDTA (NH₄)₂CO₃<EDTA NH₄OAc DTPA+CaCl₂>1M MgCl₂. Critical levels of 0.48 ppm DTPA × CaCl₂ extractable Zn, 0.80 ppm EDTA NH₄OAc extractable Zn, 0.70 ppm EDTA (NH₄)₂CO₃ extractable Zn, and 2.2 ppm 0.1N HCl extractable Zn were estimated for the soils tested. The critical Zn concentration in 6 weeks old plants was found to be 19 ppm. The 0.1N HCl method gave the best correlation (r=0.588^**) between extractable Zn and Bray's per cent yield, while with DTPA+CaCl₂, it was slightly low (r=0.542^**). The DTPA + CaCl₂ method gave significant (r=0.73^**) correlation with plant Zn concentration. The 0.1N HCl gave the higher correlation with Zn uptake (r=0.661^**) than DTPA (r=0.634^**) 6N HCl and 1M MgCl₂ method gave nonsignificant positive relationship with Bray's per cent yield. For noncalcareous soils apart from the common use of DTPA+CaCl₂, 0.1N HCl can also be used for predicting soil available Zn. The use of 0.1N HCl would be much cheaper than DTPA and other extractants used in the study.     

Radioimmunoassay for plasma betamethasone 17-benzoate.

A sensitive radioimmunoassay for plasma betamethasone 17-benzoate has been developed. The antiserum used was obtained by immunizing rabbits with betamethasone 17-benzoate-21-hemisuccinate-bovine-serum-albumin conjugate. All of the endogenous steroids tested cross reacted less than 0.10%. A standard curve was established with a useful range from 0.05-5 ng. Reliability criteria were satisfactory. Measurement of plasma concentrations of betamethasone 17-benzoate was performed in patients and in rabbits following occlusive dressing of betamethasone 17-benzoate cream and gel base.     

Influence of CCK and bombesin on ACTH and cortisol secretion in the conscious dog

Bombesin and cholecystokinin (CCK) have a variety of similar actions. Previous investigations have demonstrated that IP injections of bombesin and CCK-33 increased corticosterone secretion in conscious, freely-moving, fed rats. In this study bombesin or CCk-8 was administered by continuous, intravenous infusion to conscious, awake, fasted, mongrel dogs. Following a 30-40 minute control infusion, a progressively-increasing, stepwise infusion of either bombesin (0.1, 1.0 and 2.0 micrograms/kg-hr) or CCK-8 (62.5, 125, and 250 ng/kg-hr) was administered. Each drug dose was infused for 40-45 minutes and blood samples were drawn at 20-22.5 minutes intervals. Bombesin caused significant, dose-dependent increases in plasma cortisol (286 +/- 39% of control) and plasma ACTH (176 +/- 33% of control). CCK-8 had no consistent effect on either cortisol or ACTH secretion. Whether the lack of effect of CCK-8 in dogs, as compared to rats, is due to species variations or to the differing experimental designs is unknown.     

The Life Cycle of Cryptochlora perforans (Chlorarachniophyta)

Observations on the behaviour of different life cycle stages, gamete fusions, and measurements of nuclear DNA contents in Cryptochlora perforans resulted in a first concept concerning life histories in Chlorarachniophyta: the life cycle of Cr. perforans is diplohaplontic (gamete fusion with karyogamy - mitosis - meiosis - mitosis). In the haploid as well as in the diploid life cycle phases amoeboid and coccoid stages occur. The isomorphic gametes are modified amoebae frequently without filopodia. Only haploid flagellate stages are known representing mito- or meiozoospores. Diploid coccoid stages have a granular cytoplasmic structure and may be somewhat larger than haploid ones. Nevertheless, positive identification of haploid (gametophytic) and diploid (sporophytic) stages is only possible on the basis of nuclear DNA contents.     

Establishing the European diagnostic reference levels for interventional cardiology

Interventional cardiac procedures may be associated with high patient doses and therefore require special attention to protect the patients from radiation injuries such as skin erythema, cardiovascular tissue reactions or radiation-induced cancer. In this study, patient exposure data is collected from 13 countries (37 clinics and nearly 50 interventional rooms) and for 10 different procedures. Dose data was collected from a total of 14,922 interventional cardiology procedures. Based on these data European diagnostic reference levels (DRL) for air kerma-area product are suggested for coronary angiography (CA, DRL = 35 Gy cm²), percutaneous coronary intervention (PCI, 85 Gy cm²), transcatheter aortic valve implantation (TAVI, 130 Gy cm²), electrophysiological procedures (12 Gy cm²) and pacemaker implantations. Pacemaker implantations were further divided into single-chamber (2.5 Gy cm²) and dual chamber (3.5 Gy cm²) procedures and implantations of cardiac resynchronization therapy pacemaker (18 Gy cm²). Results show that relatively new techniques such as TAVI and treatment of chronic total occlusion (CTO) often produce relatively high doses, and thus emphasises the need for use of an optimization tool such as DRL to assist in reducing patient exposure. The generic DRL presented here facilitate comparison of patient exposure in interventional cardiology.     

Artificial radiofrequency driven life-table parameters of perilla seed bugs (Nysius sp.) (Heteroptera: Lygaeidae)

The genus Nysius (Hemiptera: Lygaeidae) are polyphagous pests of various plants that damage seeds, foliage, and flowers. Here, we studied the life-table parameters and adult performances of Nysius plebeius Distant and Nysius hidakai Nakatani after exposure to five radiofrequencies: 0 (control), 5, 10, 20, and 30 kHz in infested perilla seeds. In addition, we measured the follow on effects of treatment for four generations (Parent, F1-, F2-, and F3-generation), for both Nysius species. Radiofrequency application significantly affected the life-table parameters of both Nysius species. Radiofrequency exposures affected bug oviposition, developmental period, adult weight, and longevity. Exposure also negatively affected the fecundity of subsequent generations; total developmental period from egg to adult emergence was longer while adult longevity was shorter in the radiofrequency treatments than in the untreated control. Low radiofrequency levels had the greatest effect on the life-table parameters of Nysius species, with the lowest rate of adult emergence and the shortest adult longevity at 5 kHz. The potential of using Nysius bug susceptibilities to radiofrequency as an alternative to chemical treatment is discussed.     

Grazing simplifies soil micro‐food webs and decouples their relationships with ecosystem functions in grasslands

Livestock grazing often alters aboveground and belowground communities of grasslands and their mediated carbon (C) and nitrogen (N) cycling processes at the local scale. Yet, few have examined whether grazing‐induced changes in soil food webs and their ecosystem functions can be extrapolated to a regional scale. We investigated how large herbivore grazing affects soil micro‐food webs (microbes and nematodes) and ecosystem functions (soil C and N mineralization), using paired grazed and ungrazed plots at 10 locations across the Mongolian Plateau. Our results showed that grazing not only affected plant variables (e.g., biomass and C and N concentrations), but also altered soil substrates (e.g., C and N contents) and soil environment (e.g., soil pH and bulk density). Grazing had strong bottom‐up effects on soil micro‐food webs, leading to more pronounced decreases at higher trophic levels (nematodes) than at lower trophic levels (microbes). Structural equation modeling showed that changes in plant biomass and soil environment dominated grazing effects on microbes, while nematodes were mainly influenced by changes in plant biomass and soil C and N contents; the grazing effects, however, differed greatly among functional groups in the soil micro‐food webs. Grazing reduced soil C and N mineralization rates via changes in plant biomass, soil C and N contents, and soil environment across grasslands on the Mongolian Plateau. Spearman's rank correlation analysis also showed that grazing reduced the correlations between functional groups in soil micro‐food webs and then weakened the correlation between soil micro‐food webs and soil C and N mineralization. These results suggest that changes in soil micro‐food webs resulting from livestock grazing are poor predictors of soil C and N processes at regional scale, and that the relationships between soil food webs and ecosystem functions depend on spatial scales and land‐use changes.