黄药,黑药,二号油在水体中的降解试验研究

本文总结了黄药，黑药，二号油在水体中降解变化规律和其影响因素，为治理浮选废水，预测其对自然环境影响提供了科学依据。     

Fat-free mass, total body water, and intracellular water in the aged rat

Total body water (TBW) and intracellular water (ICW = TBW minus extracellular water), when related to fat-free body mass (FFB), were recently observed to remain stable in healthy aged men and women. To expand these findings, a group of male Sprague-Dawley rats was followed from weaning to death. The design minimized several perturbations common to aging studies. At about 100-day intervals from 297 to 888 days, representative animals were killed for chemical studies. TBW/FFB was stable from 362 to 715 days, then significantly higher at 800 and 888 days. Extracellular water content of the fat-free body (ECW/FFB) increased significantly during middle life (362--579 days), then remained stable through 888 days. Changes of ICW/FFB were not significant. Aside from a uniquely higher value at 638 days, protein content did not differ significantly at any age. The stability of these major constituents suggested approximate maintenance of cell mass in healthy rats at late ages, a conclusion supported by additional observations of this colony and of an aged human population. We are unable to confirm the hypothesis that loss of FFB is part of the normal aging process.     

Bedside diagnostic testing of body fluids

Numerous bedside diagnostic modalities are appropriate for the practice of emergency medicine. The proliferation of sophisticated technology is likely to increase both the availability and accuracy of commercial testing products. If health care reform in the United States results in a relaxation of the CLIA regulations, there will be a rapid expansion of research and development aimed at the biotechnology market. How much this would pertain to hospital-based emergency practice remains to be seen. Cost containment pressures may act in both directions on the utilization of available bedside technology. Although these tests are often less expensive than centralized laboratory determinations, the ready availability of near-patient testing may result in an increase in use that negates the lower cost. As with other diagnostic modalities, a thoughtful, considered approach based on scientific evidence will be necessary to formulate the appropriate use of bedside testing in individual emergency practice settings.     

Bioimpedance spectroscopy technique: intra-, extracellular, and total body water

The purpose of this study was to test the validity of a multiple frequency bioimpedance spectroscopy (BIS) technique that estimates extracellular fluid volume (ECV), intracellular fluid volume (ICV), and total body water (TBW). Thirteen healthy males (mean +/- SD: age, 23 +/- 3 yr; body mass, 80.6 +/- 14.7 kg) had their TBW and ECV measured by ingesting dilution tracers (7.27 g deuterium oxide, 1.70 g sodium bromide; blood samples at 0 and 4 h). ICV was calculated as TBW minus ECV. Impedance was measured (50-500 kHz) at rest, on a nonconducting surface, with a BIS analyzer. Electrode placement, posture, exercise, food/fluid intake, and ambient temperature were controlled. Dilution measures (TBW, 51.00 +/- 9.30; ECV, 19.88 +/- 3.14; ICV, 31.12 +/- 6.80 L) and BIS volumes (TBW, 50.03 +/- 7.67; ECV, 20.95 +/- 3.33; ICV, 29.04 +/- 4.51 L) were significantly different for ECV (P < 0.01) and ICV (P < 0.05); some individual differences were large. The correlation coefficients of dilution versus BIS volumes (r = 0.93 to 0.96) were significant at P < 0.0001; SEEs were: TBW, 2.23 L; ECV, 1.26 L; and ICV, 1.71 L. We concluded that BIS is valid for between-subject comparisons of body fluid compartments, is appropriate in clinical settings where change in ECV/ICV ratio is important, and should be used by comparing the required level of accuracy to the inherent technique error/variance.     

Oral toxicity in mice of algal toxins from the diarrheic shellfish toxin (DST) complex and associated toxins

Mussel samples from four locations along the Norweigian coast were extracted by methods for diarrheic shellfish toxins (DST) and tested by chemical and biological methods, including histopathology. All samples had previously been found to be highly toxic in mice, with symptoms indicating the presence of non-diarrheagenic toxins in the mouse bioassay. Chemical analysis revealed that the DST okadaic acid (OA) and dinophysistoxin-1 (DTX1) were present each one in one sample, but only a minor part of the total toxicity could be attributed to these toxions. In the other two samples, OA and DTX1 were absent. Incubation of the mussel extracts from all four samples with freshly prepared hepatocytes indicated the presence of unknown toxin(s) which may not be classified within the DST complex. Purified mussel samples were given to baby mice both via intraperitoneal (i.p.) injections and by oral intubation. Oral toxicity was about 25-50 times lower than toxicity obtained by i.p. injections, a result in accordance with acute toxic properties of many toxins. Risk assessment of the unknown toxin(s) requires chemical identification, but the preliminary results obtained indicate a large margin of safety, based on the large amounts of mussel extracts necessary to yield toxic effects in the intestine and liver in experimental animals upon oral exposure versus human intake.     

Development and use of a multiplex PCR system for the rapid screening of heat labile toxin I, heat stable toxin II and shiga-like toxin I and II genes of Escherichia coli in water

Enterotoxigenic Escherichia coli (ETEC) may produce heat-labile toxin (LT) I and LTII and heat-stable toxin (ST) I and STII, while shiga toxin producing E. coli (STEC) strains, including enterohaemorrhagic E. coli (EHEC), may produce shiga-like toxin (SLT) I and/or SLTII. Both ETEC and STEC are pathogenic to humans, pigs and cattle. As contamination of environmental water by any of these pathogenic E. coli cells is possible, a multiplex polymerase chain reaction (PCR) system for the rapid screening of LTI, STII, and SLTI and SLTII genes of E. coli was developed. The PCR primers used were the SLTI and SLTII genes specific primers developed by the present authors and the LTI and STII genes specific primers reported by other laboratories. The detection specificity of this multiplex PCR system was confirmed by PCR assay of ETEC, STEC and other E. coli cells as well as non-E. coli bacteria. Its detection limit was 10(2)-10(3) cfu each of the target cells per assay. When this multiplex PCR system was used for the rapid screening of LTI, STII ETEC and STEC in water samples such as tap, underground and lake waters, it was found that after the enrichment step, as few as 10(0) cells 100 ml-1 of the water sample could be detected. Therefore, this PCR system could be used for the rapid monitoring of ETEC and/or STEC cells contaminating water samples.     

矩形镍铁电炉炉体的膨胀与检测

叙述了矩形镍铁电炉炉体的结构特点以及炉体膨胀检测的意义与方法,介绍了某大型矩形镍铁电炉开炉过程中炉体的膨胀及检测情况.     

Measurement of total body water content in horses, using deuterium oxide dilution

OBJECTIVE: To measure total body water (TBW) content in horses, using deuterium oxide (D2O) dilution. ANIMALS: Six 8- to 10-year-old healthy untrained mixed-breed horses, weighing (mean +/-SD) 503.4 +/- 64.0 kg. PROCEDURE: After a 12-hour nonfeeding period, 6 horses were given D2O (0.14 g/kg of body weight) via nasogastric tube. Blood samples were collected from a preplaced indwelling jugular vein catheter prior to and 1 to 8, 10, 12, 14, and 24 hours after administration of D2O. Blood samples were centrifuged immediately, and plasma was collected and stored at -70 C until analysis. The D2O content in plasma was measured by zinc reduction to deuterium gas. The resulting gas was measured, using an isotope ratio mass spectrometer. RESULTS: Deuterium oxide was rapidly absorbed from the gastrointestinal tract of all horses, and reached peak (mean +/- SD) plasma concentration (1,454.4 +/- 163 delta D/ml or parts/thousand) 1 hour after administration. Plasma concentration decreased slowly during the next 2 to 3 hours, then remained statistically constant from 2 to 5 hours (early plateau phase) and 3 to 7 hours (late plateau phase) after administration. Mean +/- SEM TBW content was 623.0 +/- 2.2 ml/kg (62.3% of body weight) for the early plateau phase and 630.3 +/- 2.2 ml/kg (63.0% of body weight) for the late plateau phase. CONCLUSION: Deuterium oxide dilution appears to be of value for measurement of TBW content in horses, and has a 4-hour plateau effect. Equilibration of D2O with large intestinal water may be the reason for the prolonged equilibrium time and plateau effect seen in these horses. CLINICAL RELEVANCE: Deuterium oxide appears safe and efficacious for determining TBW content in horses and may be helpful for determining changes in TBW content during exercise and disease.