不同离子强度下SiO_2胶体对磺胺嘧啶土壤吸附迁移行为的影响

通过室内批实验和土柱出流实验,以二氧化硅胶体作为外源胶体,定量分析了改变离子强度时胶体对磺胺嘧啶(Sulfadiazine,SDZ)在土壤中吸附、迁移行为的影响。批实验结果表明,离子强度为0.001、0.003 mol L-1时胶体的加入能够抑制SDZ的吸附,而0.005、0.010 mol L-1时胶体的加入对SDZ吸附的影响与SDZ初始浓度有关。Freundlich模型能较好地拟合SDZ在土壤中的吸附情况,R2在0.958~0.997范围内。土柱实验结果表明,不加胶体时,高离子强度会促进SDZ在土壤中的迁移,SDZ在土柱中出流早,相对浓度峰值高且持续时间长;加胶体时,高离子强度下胶体出流量小,抑制SDZ在土壤中的迁移,SDZ的相对浓度峰值降低且更难洗脱,而低离子强度时胶体全部或部分出流,促进SDZ的迁移,SDZ出流早且相对浓度峰值高。总之,吸附迁移实验表明,低离子强度时,胶体的加入促进了SDZ的迁移抑制SDZ的吸附,高离子强度时则相反。该结果有助于全面理解土壤中磺胺类抗生素的运移,指导磺胺类抗生素的风险评估及防治。     

CANINE VENTRAL BODY WALL LYMPHOSCINTIGRAPHY

The scintigraphic characteristics of lymph nodes draining the ventral body wall were analyzed in 12 dogs as to their pattern of appearance and image contrast. Each dog was scanned using ^99mTc-antimony sulfide colloid and ^99mTc-dextran, and the imaging characteristics of these agents were compared. A large degree of variability exists in the number and pattern of lymph node appearance with either agent. No significant difference in average numbers of lymph nodes per dog was shown between agents. However, ^99mTc-antimony sulfide colloid provided a significantly (p<.05) better target-to-background ratio, which determines the contrast with which lymph nodes stand out from background activity. From these findings, it is suggested that too great a variability in lymph node appearance exists using this procedure to allow a high degree of confidence in the diagnosis of metastasis to lymph nodes of the ventral body wall. However, for other purposes, ^99mTc-antimony sulfide colloid is the lymphoscintigraphic agent of choice.     

The use of 25% human serum albumin: outcome and efficacy in raising serum albumin and systemic blood pressure in critically ill dogs and cats

Objective: To report on the use of 25% human serum albumin (25% HSA) (Plasbumin®), associated outcome, and efficacy in raising serum albumin and systemic blood pressure (BP) in critically ill dogs and cats. Design: Retrospective clinical study. Animals: Client‐owned cats and dogs. Interventions: Administration of 25% HSA. Measurements and main results: The medical records of 66 animals (64 dogs, 2 cats) at the Ontario Veterinary College, which received 25% HSA (Plasbumin®) from June 1997 to December 2001 were reviewed for age, body weight, clinical problems, albumin and globulin (g/L) levels pre‐ and within 18‐hour post‐transfusion and upon discharge from hospital, total solids (TS), systolic and diastolic BP pre‐ and post‐transfusion total volume administered, adverse reactions, blood products and synthetic colloids used, and outcome. Twenty‐five percent HSA was prescribed for a range of clinical problems, which were grouped into 6 categories for analysis. The age range was 4 months–12 years and body weight range 1.4–65 kg. The maximum volume administered to any dog was 25 mL/kg, mean volume administered was 5 mL/kg, maximum volume given as a slow push or bolus was 4 mL/kg with a mean of 2 mL/kg volume. The range for a constant rate infusion (CRI) was 0.1–1.7 mL/kg/hr over 4–72 hours. Forty‐seven (71%) animals survived to discharge; 11(16%) were euthanized, and 8 (12%) died. Serum albumin and TS increased significantly (P<0.0001) above pre‐transfusion levels as did systolic BP (P<0.01). Conclusions: Twenty‐five percent HSA can be safely administered to critically ill animals, and an increase in albumin levels and systemic BP can be expected.     

Fluid therapy for the traumatized patient

Objective: To review the rationale behind and experiences with traditional and newly evolving concepts of fluid therapy in the traumatized patient, and to review conventional and novel fluid preparations for use in trauma resuscitation. Data sources: Human and veterinary clinical and research studies. Human data synthesis: Current treatment guidelines recommend aggressive fluid resuscitation with lactated ringers solution (LRS) or saline as optimum management of hemorrhagic shock in trauma, regardless of whether bleeding is controlled or not. The rationale behind this strategy is to restore intravascular volume as rapidly as possible to ensure adequate vital organ perfusion. Recently, this strategy has been challenged, especially in patients with uncontrolled hemorrhage, as neither laboratory evidence nor clinical trials support this practice. Current research indicates that vigorous fluid infusion may exacerbate bleeding and cause severe hemodilution, both impairing resuscitation outcome. As a result, a new line of thinking is emerging that balances the risks and benefits of intravenous volume infusion by offering the clinician alternative treatment strategies and emphasizes continuous endpoint‐oriented monitoring. ‘Hypotensive’ or ‘hypovolemic’ resuscitation techniques as well as initial volume replacement with fluids other than LRS or saline (e.g., hypertonic saline [HTS], HTS with dextran 70 [HTS‐D]) have been introduced in human medical practice as additional options for treatment of victims of trauma under certain circumstances. Clinical studies evaluating the use of hemoglobin‐based oxygen carriers (HBOCs) in the trauma setting are underway and may soon lead to an expansion of the fluid arsenal available to the clinician for treatment of trauma patients. Veterinary data synthesis: Based on available animal data, neither strict guidelines nor a clear fluid preference for resuscitation of traumatic shock have been defined. Although systematic clinical trials are missing, combinations of crystalloid and colloid (natural or artificial) appear to be as effective for resuscitation as crystalloid alone. Judicious use of an HBOC (e.g., Oxyglobin^®) as a substitute for blood/red blood cells may be recommended in situations where whole blood or pRBCs are not or not yet available. Conclusions: The search for optimal methods of fluid resuscitation in trauma is ongoing. At this point the best solution is a differentiated approach to fluid therapy, one that tailors type and volume of resuscitation solution(s) used to the type and severity of injury in an individual patient and uses monitoring of perfusion and oxygenation parameters to guide resuscitation. Crystalloid fluids are effective for resuscitation but may need to be combined with or replaced by colloidal fluids in certain clinical situations.     

Single Layer Centrifugation with 20% or 30% Porcicoll separates the majority of spermatozoa from a sample without adversely affecting sperm quality

Centrifugation of boar semen through one layer of 40% colloid (Porcicoll) was previously shown to separate spermatozoa from bacteria without having a detrimental effect on sperm quality. However, some spermatozoa were lost. The purpose of the present study was to determine whether 20% or 30% Porcicoll could be used to recover most of the spermatozoa without impacting on sperm quality. Insemination doses (n = 10) from a commercial boar station were sent to the laboratory at the Swedish University of Agricultural Sciences and processed by Single Layer Centrifugation with 20% and 30% Porcicoll approximately 7 hr after semen collection. The resulting sperm samples and controls were evaluated for sperm quality immediately and again after storage at 16–18°C for 4 and 7 days. Sperm recovery was 94 ± 18% and 87 ± 15% for 20% and 30% Porcicoll, respectively (p > .05). Sperm mitochondrial membrane potential and chromatin integrity were unaffected (p > .05). The proportion of live spermatozoa producing superoxide (9 ± 8%, 7 ± 6% and 3 ± 1%; p < .05), and the proportion of spermatozoa with high stainability DNA (0.68 ± 19%, 0.61 ± 0.22% and 0.96 ± 0.23%; p < .05- <0.01), were marginally increased whereas membrane integrity, although high, was lower in the centrifuged samples than in the controls (82 ± 8%, 83 ± 5% versus 92 ± 4%; p < .05). In conclusion, centrifugation through 20% or 30% Porcicoll enables most spermatozoa to be recovered, without having a major effect on sperm quality. These results are encouraging for further studies involving microbiological investigation of the processed samples, and scaling-up to process larger volumes of boar ejaculates.     

四川盆地紫色水稻土胶体电荷性质研究

四川盆地中性，石灰性和酸性紫色水稻土胶体负电荷分别为47.9±9.7、37.6±10.0和48.2±11.0m·e/100g，负电荷密度分别为15.2±3.1、12.2±3.2和10.1±2.3μc/cm^2。负电荷性质极大地受蒙脱石、蛭石、14A°过渡矿物含量的影响。pH值对酸性紫色水稻土胶体负电荷的影响最大，其次是中性和石灰性紫色水稻土，3种土壤胶体有90%以上的负电荷是永久负电荷，有机质对3种土壤胶体负电荷的影响不明显，罢 游离氧化铁后，3种土壤胶体负电荷均有降低趋势。去除非晶质氧化铝能显地释放负电荷点，羟基释放量与电荷的pH值因变性之间有密切关系。     

胶体配制探索

制备胶体溶液的方法很多,许多教学书参考书中都有介绍,但实践中都往往出现异常,以 Fe(OH)_3胶体的制备介绍制备条件方法的最优选择.