The effect of dicoumarol and aesculine on the accumulation ofD-galactose by the intestinal rings of hamsters

Summary The accumulation ofD-galactose by rings of hamster small intestine shows a Michaelis-Menten kinetics with an apparent K_m of 5.5 mM and a maximum rate of net penetration of 0.35 micromoles/100 mg tissue w.w./min. Dicoumarol when present in the medium at concentrations 10^–5 to 10^–4 M, markedly inhibits (40–72%) galactose accumulation, behaving as a noncompetitive inhibitor with an apparent K_i of 5.5×10^–5 M. The drug also inhibits the oxygen uptake by the tissue in the absence of added substrate.Inhibition of galactose active transport by dicoumarol was also observed if the incubation was carried out after a preincubation with the drug. This effect could not be eliminated by repeated washings of the rings after preincubation.The effects of dicoumarol are explained as due to binding to cellular constituents and to inhibition of cell metabolism. Aesculine up to 10^–4 M concentration does not affect galactose accumulation.     

腹上部腹膜腔积液的CT研究

目的　探讨腹上部腹膜腔积液的ＣＴ 分布特点及断层解剖学基础。方法　搜集１３８ 例腹上部腹膜腔积液者,按不同积液量分为少量、中等量、大量３ 组,观察腹上部腹膜腔积液分布的规律及对少量积液的敏感解剖部位。结果　右肝上间隙积液显示率最高,左肝上后间隙显示率最低,肝周间隙显示率高于脾周间隙,右肝周间隙高于左肝周间隙。腹上部腹膜腔中对少量积液最易显示的部位是右肝上间隙而不是肝肾隐窝。结论　腹上部腹膜腔积液的分布遵循力学原则,符合解剖学基础。对少量积液显示最敏感的部位是右肝上间隙。     

Hexavalent chromium induced stress and metabolic responses in hybrid willows

Metabolic responses to hexavalent chromium (Cr⁶⁺) stress and the uptake and translocation of Cr⁶⁺ were investigated using pre-rooted hybrid willows (Salix matsudana Koidz × Salix alba L.) exposed to hydroponic solution spiked with K₂CrO₄ at 24.0 ± 1°C for 192 h. Various physiological parameters of the plants were monitored to determine toxicity from Cr⁶⁺ exposure. At Cr⁶⁺ treatments of ≤2.1 mg Cr/l, the transpiration rate of plants was > 50% higher than that of the non-treated control plants. As Cr concentrations were increased further, a slight increase in the transpiration rate was also observed compared with the controls. Negligible difference in the chlorophyll contents in leaves between the treated and the non-treated control plants was measured, except for willows exposed to 1.05 mg Cr/l. The response of soluble proteins in leaves of willows to Cr treatments was remarkable. Cr-induced toxicity appeared in all treatments resulting in reduced activities of catalase (CAT) and peroxidase (POD) compared to the controls. Superoxide dismutases (SOD) activity in the leaf cells showed a positive increase after Cr exposure. Of all selected parameters, soluble proteins in leaves were the most sensitive to Cr⁶⁺ doses, showing a significant linear correlation negatively (R ² = 0.931). Uptake of Cr⁶⁺ by willows grown in flasks was found to increase linearly with the added Cr⁶⁺ (a zero order kinetics), as indicated by the high R ² (0.9322). Recovery of Cr in different parts of plant materials varied significantly with roots being the dominant site of Cr accumulation. Although the translocation to shoots was detected, the amount of Cr translocated to shoots was considerably small. The capacity of willows to assimilate Cr⁶⁺ was also evaluated using detached leaves and roots in sealed glass vessels in vivo. Uptake of Cr by roots was mediated possibly through an active transport mechanism, whereas the cuticle of leaves was the major obstacle to uptake Cr from the hydroponic solution. In addition, both cysteine and ascorbic acid showed a remarkable potential to reduce Cr⁶⁺ at a neutral pH. Results indicated that the added Cr did not cause deleterious effects on plant physiological functions over a 192-h period of exposure. Significant removal of Cr from the hydroponic solution was observed in the presence of hybrid willows. The data also suggest that phytoremediation of Cr⁶⁺ is possible and ecologically safe due to the minor translocation of Cr to aerial tissues.     

Cadmium accumulation,sub-cellular distribution and chemical forms in rice seedling in the presence of sulfur

Changes in cadmium (Cd) accumulation, distribution, and chemical form in rice seedling in the joint presence of different concentrations of sulfur (S) remain almost unknown. Therefore, the indoor experiments were performed to determine the accumulation, sub-cellular distribution and chemical forms of Cd under three S levels in rice seedling for the first time. The result showed that Cd accumulation in rice roots was more than in shoots. Sub-cellular distribution of Cd in rice roots and shoots indicated that the largest proportion of Cd accumulated in cell walls and soluble fractions. As S supply increased, the proportion of Cd in cell walls reduced, while it increased in the soluble fractions. The majority of Cd existed in inorganic form, and then gradually changed to organic forms that included pectates and proteins with increased S supply. The results showed that S supply significantly influenced Cd accumulation, distribution, and chemical forms, suggesting that S might provide the material for the synthesis of sulfhydryl protein and thereby affect Cd stress on plants. These observations provided a basic understanding of potential ecotoxicological effects of joint Cd and S exposure in the environment.     

RESISTANT MECHANISMS OF CISPLATIN IN HUMAN LUNG ADENOCARCINOMA CELL LINE A_(549)DDP

ＲＥＳＩＳＴＡＮＴＭＥＣＨＡＮＩＳＭＳＯＦＣＩＳＰＬＡＴＩＮＩＮＨＵＭＡＮＬＵＮＧＡＤＥＮＯＣＡＲＣＩＮＯＭＡＣＥＬＬＬＩＮＥＡ５４９ＤＤＰＺｈａｎＭａｏｃｈｅｎｇ詹茂程ＬｉｕＸｕｙｉ刘叙仪ＣａｉＰｅｎｇ蔡鹏ＸｕＧｕａｎｇｗｅｉ徐光炜ＳｃｈｏｌｏｆＯ...     

南方某地产妇和婴儿体内多氯联苯蓄积水平的调查

目的了解我国南方某多氯联苯(PCBs)高暴露地区的产妇及其婴儿体内PCBs的蓄积水平。方法采集在当地某医院中符合条件的50对母婴对的母乳和脐带血,用GC-MS法进行PCBs含量的测定。结果母乳中13种PCBs总浓度的最大值为237 ng/g类脂,几何均数为138 ng/g类脂。脐带血中13种PCBs总浓度的最大值为102 ng/g类脂,几何均数为56.9 ng/g类脂。结论该地区妇女和婴儿体内普遍检测出较高水平的PCBs     

Accumulation and metabolism of arsenic in mice after repeated oral administration of arsenate

Exposure to the human carcinogen inorganic arsenic (iAs) occurs daily. However, the disposition of arsenic after repeated exposure is not well known. This study examined the disposition of arsenic after repeated po administration of arsenate. Whole-body radioassay of adult female B6C3F1 mice was used to estimate the terminal elimination half-life of arsenic after a single po dose of [(73)As]arsenate (0.5 mg As/kg). From these data, it was estimated that steady-state levels of whole-body arsenic could be attained after nine repeated daily doses of [(73)As]arsenate (0.5 mg As/kg). The mice were whole-body radioassayed immediately before and after the repeated dosing. Excreta were collected daily and analyzed for arsenic-derived radioactivity and arsenicals. Whole-body radioactivity was determined 24 h after the last repeated dose, and five mice were then euthanized and tissues analyzed for radioactivity. The remaining mice were whole-body radioassayed for 8 more days, and then their tissues were analyzed for radioactivity. Other mice were administered either a single or nine repeated po doses of non-radioactive arsenate (0.5 mg As/kg). Twenty-four hours after the last dose, the mice were euthanized, and tissues were analyzed for arsenic by atomic absorption spectrometry (AAS). Whole-body radioactivity was rapidly eliminated from mice after repeated [(73)As]arsenate exposure, primarily by urinary excretion in the form of dimethylarsinic acid (DMA(V)). Accumulation of radioactivity was highest in bladder, kidney, and skin. Loss of radioactivity was most rapid in the lung and slowest in the skin. There was an organ-specific distribution of arsenic as determined by AAS. Monomethylarsonic acid was detected in all tissues except the bladder. Bladder and lung had the highest percentage of DMA(V) after a single exposure to arsenate, and it increased with repeated exposure. In kidney, iAs was predominant. There was a higher percentage of DMA(V) in the liver than the other arsenicals after a single exposure to arsenate. The percentage of hepatic DMA(V) decreased and that of iAs increased with repeated exposure. A trimethylated metabolite was also detected in the liver. Tissue accumulation of arsenic after repeated po exposure to arsenate in the mouse corresponds to the known human target organs for iAs-induced carcinogenicity.     

Accumulation of gliotoxin, a cytotoxic mycotoxin from Aspergillus fumigatus, in blue mussel (Mytilus edulis).

A strain of Aspergillus fumigatus has been isolated from sediments of a mussel bed. When cultured in hyper saline conditions (with sea-water), it produces a cytotoxic and immunosuppressive toxin, gliotoxin, which is excreted in an exudate. In order to know if this toxin could represent a risk for shellfish consumers, an experiment of bioaccumulation of gliotoxin in mussel has been carried out. After 6 days of contamination, toxin was accumulated in the meat of the mussels, at a level up to 2.9 microg/mg of extract weight, with a mode of contamination different to the classical digestive process described for a majority of marine toxins, but similar to the contamination mode of domoic acid.     

Acute toxicity, accumulation and tissue distribution of copper in the blue crab Callinectes sapidus acclimated to different salinities: in vivo and in vitro studies

In vivo and in vitro studies were performed to evaluate acute toxicity, organ-specific distribution, and tissue accumulation of copper in Callinectes sapidus acclimated to two different experimental salinities (2 and 30 ppt). Blue crabs were quite tolerant to copper. Acute dissolved copper toxicity (96-h LC₅₀ and its corresponding 95% confident interval) was higher at salinity 2 ppt (5.3 (3.50-8.05) μM Cu) than at 30 ppt (53.0 (27.39-102.52) μM Cu). The difference between salinities can be completely explained based on the water chemistry because it disappeared when 96-h LC₅₀ values were expressed as the free Cu²⁺ ion (3.1 (1.93-4.95) μM free Cu at 2 ppt versus 5.6 (2.33-13.37) μM free Cu at 30 ppt) or the Cu²⁺ activity (1.4 (0.88-2.26) μM Cu activity at 2 ppt versus 1.7 (0.71-4.07) μM Cu activity at 30 ppt). The relationships between gill Cu burden and % mortality were very similar at 2 and 30 ppt, in accord with the Biotic Ligand Model. In vivo experiments showed that copper concentration in the hemolymph is not dependent on metal concentration in the surrounding medium at either experimental salinity. They also showed that copper flux into the gills is higher than into other tissues analyzed, and that anterior and posterior gills are similarly important sites of copper accumulation at both experimental salinities. In vitro experiments with isolated-perfused gills showed that there is a positive relationship between copper accumulation in this tissue and the metal concentration in the incubation media for both anterior and posterior gills. A similar result was observed at both low and high salinities. Furthermore, in vitro experiments showed that copper accumulation in posterior gills is also positively and strongly dependent on the incubation time with copper. Gill copper accumulation occurred at a lower rate in the first 2 h of metal exposure, increasing markedly after this “steady-state” period. This finding was corroborated by a significant increase in copper influx to the gill perfusate (corresponding to crab hemolymph) after this time, measured using ⁶⁴Cu. In vivo, after uptake from solution, ⁶⁴Cu was primarily accumulated in the gills and the rest of the body rather than in the hemolymph, hepatopancreas, or other internal tissues. Overall, the present findings indicate that gills are a key target organ for copper accumulation, as well as an important biological barrier against the excessive uptake of copper into the hemolymph and the subsequent distribution of this metal to internal organs of the blue crab.     

POPs accumulated in fish and benthos bodies taken from Yangtze River in Jiangsu area

The persistent organic pollutants of DDTs, PCBs, PAHs and HCHs accumulated in the bodies of fish and benthos taken at seven sites were measured to understand the issue of ecological health of Yangtze River at Jiangsu section. The highest levels for DDTs, the total 20 PCBs, the total 16 PAHs and HCHs in fish bodies were 0.076 μg/kg, 23.1 μg/kg, 7.44 ng/kg and 0.028 μg/kg, respectively and that in benthos bodies were 0.082 μg/kg, 14.3 μg/kg, 21.1 ng/kg and 0.026 μg/kg. The PAHs concentrations in benthos were higher than that in fish and they had a significant positive correlation (P < 0.05). Among the detectable chemicals, DDTs were 100% of p,p′-DDE isomers, the main PCBs were 4- and 5-chlorinated biphenyls in which PCB 105 had the highest detection frequency and the main PAHs were the compounds of 2–4 rings. PCBs were accumulated in fish bodies which enrichment factors were as high as 508–42,414 folds occurred at three sites. The results demonstrated that the accumulation measurements can be used to test the effects of PAHs, DDTs, PCBs and HCHs on aquatic ecological health.