Continuous arteriovenous hemodialysis: an alternative therapy for acute renal failure associated with critical illness.

Critically ill patients often cannot tolerate conventional hemodialysis because of hemodynamic instability. Continuous arteriovenous hemofiltration provides control of fluid and electrolyte balance but is inefficient in the management of azotemia. Continuous arteriovenous hemodialysis (CAVHD) combines dialysis with hemofiltration. We performed 15 CAVHD treatments of 2 or more days'' duration in 12 critically ill patients aged 23 to 85 (mean 64.4) years who had acute oliguric renal failure as a component of multiple organ system failure and who were unsuitable for conventional hemodialysis. The total treatment time was 106 days. The serum creatinine and urea levels were controlled in all the patients during CAVHD. The ultrafiltrate losses were sufficient to allow appropriate nutrition and fluid administration and still maintain a negative fluid balance. Renal function returned in five patients (42%), of whom four survived to be discharged home. CAVHD is an effective means of managing acute oliguric renal failure in critically ill patients.     

Hydrazine stress in the diabetic: ornithine decarboxylase activity

Streptozotocin-induced diabetes of 7 weeks duration increased male Sprague-Dawley rat kidney ornithine decarboxylase activity by 4.8-fold but did not affect the liver enzyme. Hydrazine treatment of 4 hr duration stimulated equally kidney ornithine decarboxylase activities of nondiabetic and diabetic rats. Hydrazine treatment increased liver ornithine decarboxylase activity in the nondiabetic rat but did not increase it in the diabetic rat. Since hydrazine stimulates ornithine decarboxylase activity prior to polyamine and protein syntheses, we speculate that the lack of hydrazine stimulation of ornithine decarboxylase in the diabetic liver may be related in part to the unrestrained gluconeogenesis and depressed Kreb's cycle activity: the latter being required for protein synthesis.     

微量元素对虫草蝠蛾幼虫生长发育的影响

按月采样,分析测定虫草蝠蛾幼虫体微量元素的组成。应用Q模式系统聚类方法,分析了幼虫受环境影响引起的元素代谢变化。结果表明虫体所含元素与环境温度的变化及自身的生理活动密切相关。5、10月份幼虫组的元素含量相近,前者正当幼虫结束休眠后恢复活动的时期,后者是幼虫处于准备进入越冬的前期,两组幼虫此时均处于取食高峰期。3、4月份组的亦较接近,幼虫正渐恢复活动但不取食。8月份幼虫蜕皮前后,消耗较大,需摄取大量食物。计算结果表明7、9月份的元素含量接近,这与上述现象有一定联系;应用对应因子分析法得到的结果是:元素Fe、P对10、11月份幼虫组的贡献值显著;Na、Ca、Mg对8、9月份的贡献值显著;Cu、Zn、Co、Cd、Si对4、5月份的贡献值显著。     

Identification of the ATP·Mg-dependent protein phosphatase activator (Fa ) as a synapsin I kinase that inhibits cross-linking of synapsin I with brain microtubules

The ATP·Mg-dependent protein phosphatase activating factor (Fa) has been identified and purified to near homogeneity from brain. In this report, as evidenced on SDS-polyacrylamide gel electrophoresis followed by autoradiography, factorFa has further been identified as a cAMP and Ca²⁺-independent brain kinase that could phosphorylate synapsin I, a neuronal protein that coats synaptic vesicles, binds to cytoskeleton, and is believed to be involved in the modulation of neurotransmission. Kinetic study further indicated that factorFa could phosphorylate synapsin I with a lowK _m value of about 2 µM and with a molar ratio of 1 mol of phosphate per mole of protein. Peptide mapping analysis revealed that factorFa specifically phosphorylated the tail region of synapsin I but on a unique site distinct from those phosphorylated by Ca²⁺/calmodulin-dependent protein kinase II and cAMP-dependent protein kinase, the two well-established synapsin I kinases. Functional study further revealed that factorFa could phosphorylate this unique specific site on the tail region of synapsin I and thereby inhibit cross-linking of synapsin I with microtubules. The results further suggest the possible involvement of factorFa as a synapsin I kinase in the regulation of axonal transport process of synaptic vesicles via the promotion of vesicles motility during neurotransmission.     

Effects of antiplatelet agents on platelet aggregation induced by platelet--activating factor (PAF) in human whole blood.

Impedance aggregometry was used to evaluate the potency of anti-platelet agents on Platelet Activating Factor (PAF)--induced platelet aggregation in citrated human whole blood. Drugs were tested for ability to inhibit maximum aggregation to PAF. Dose response curves were obtained and the concentration of drug producing 50% inhibition of maximum aggregation (ED50) determined. ED50's (microM) for specific PAF antagonists WEB 2086, Ro 19-3704, FR-900452, BN 52021, L-652,731, CV 3988, WEB 2118 and 48740 RP are: 0.39, 2.4, 4.7, 19.5, 21.0, 5.32, 161.0, 924.0, respectively. ED50's for non-specific PAF antagonists, diltiazem, propranolol, ketotifen, procaine HCL, and lidocaine HCL are: 38.0, 56.0, 250.0, 513.0 and 768.0, respectively. Ibuprofen was inactive at 2300 microM. Results are consistent with concept that there are specific receptors on platelets mediating PAF-induced aggregation in whole blood. Aggregation is inhibited potently by specific and competitive PAF receptor antagonists. Whole blood aggregometry may be a valid method for predicting in vivo activity of PAF antagonists.     

Stimulation of n-alkane conversion to dicarboxylic acid by organic-solvent- and detergent-treated microbes

Summary A wild-type strain of Cryptococcus neoformans and Pseudomonas aeruginosa were used to convert n-pentadecane to the corresponding dioic acid, tridecane 1,13-dicarboxylic acid (DC-15). Altering the cell permeability by treating C. neoformans with 1% (v/v) toluene or 7% (v/v) Triton X-100 stimulated production of DC-15 by 1.5-fold and fourfold, respectively. Furthermore, DC-15 productivity was increased from 2.5 mg/l per hour to 18 or 30 mg/l per hour, respectively. If 10% (v/v) hexane was used to treat the yeast culture, stimulation of DC-15 production could reach 200% and more viable cells remained compared to the toluene-treated culture. Data from the organic solvent treatment experiment indicated that the solvent with a higher polarity showed a more adverse effect on DC-15 production. P. aeruginosa was vulnerable to most organic solvents; however, Tween 80 could greatly stimulate the conversion of n-pentadecane to DC-15. Although organic solvents and non-ionic detergents could enhance DC-15 formation by microbial conversion, it was inhibited by elevated levels of DC-15.Offprint requests to: E.-C. Chan     

Genomic characterization ofCampylobacter jejuni by field inversion gel electrophoresis

The genome ofCampylobacter jejuni was characterized by field inversion gel electrophoresis (FIGE) after digestion with three rare-cutting restriction endonucleases. The restriction enzymesSac II (5-CCGCGG),Sal I (5-GTCGAC), andSma I (5-CCCGGG) were found to produce 13, 5, and 8 fragments respectively from theC. jejuni genome. The fragment sizes ranged from 1.6 kb to 1300 kb, which gaveC. jejuni a genome size of approximately 1900 kb. Furthermore, thegly A and rRNA genes ofC. jejuni were localized to specific fragments by use of Southern analysis, and thegly A gene was shown to be closely linked to one of the three rRNA genes.     

Primary sequence mapping of human apolipoprotein B-100 epitopes. Comparisons of trypsin accessibility and immunoreactivity and implication for apoB conformation

Differential trypsin-accessibility and monoclonal antibodies (Mabs) to human apolipoprotein (apo) B-100 are both important tools for probing apoB structure and conformation on low-density lipoproteins (LDL). In this study, we have mapped greater than 80% of the C-terminal region (720 residues) of LDL apoB-100 using trypsin digestion. Our results extend our previous data [Yang et al. (1986) Nature (Lond.) 323, 738-742] confirming that the C-terminal region of about 420 residues of apoB-100 is largely inaccessible to trypsin, whereas the part just preceding this region has interspersed trypsin-accessible and inaccessible peptides. We have determined the amino acid sequence of specific apoB-100 peptides containing epitopes recognized by four separate Mabs: two epitopes have been mapped to within 20 residues, one has been mapped to 36 residues, and the last to 80 residues. We used polyclonal antisera to identify 16 overlapping clones of varying lengths of apoB-100 cDNAs extending from the C-terminus of apoB-100 cloned in the expression vector, lambda gt11. These clones were then tested against individual Mabs. By nucleotide sequence analysis of overlapping clones that show differential reactivities to different Mabs, we have mapped the individual epitopes of each Mab to within about 50-150 amino acid residues predicted from the DNA sequences. Confirmation and further fine mapping were accomplished by competition for LDL binding using partially purified fusion proteins and chemically synthesized oligopeptides. Two epitopes (Mabs 7 and 22) were mapped to the C-terminal 20 amino acids of apoB-100, one (Mab 16) to residues 4154-4189, and another (Mab 20) to residues 3926-4005. Mab 16 precipitates more than 80% of LDL particles. Mab 20 precipitates only denatured apoB but not native LDL apoB [Milne et al. (1987) Mol. Immunol. 24, 435]. Mabs 7 and 22 are unique in that they precipitate LDL apoB modified by storage much better than freshly isolated LDL-apoB. Although epitope expression and trypsin-accessibility represent two useful probes for the study of protein conformation, there was no obvious correlation between these two parameters when applied to LDL apoB for the antibodies we have examined.     

The effect of repetitive haemorrhage on plasma cortisol, beta-endorphin and N-terminal pro-opiomelanocortin in conscious sheep

We measured the effect of repeated haemorrhagic stress, performed on four consecutive days in conscious adult sheep, on the plasma concentrations of cortisol and ACTH-related peptides to determine whether the pituitary-adrenal response was altered by stress repetition. Peptides from the C-terminus of the ACTH pro-hormone was measured by beta-endorphin RIA. Glycopeptides derived from the N-terminus of the ACTH pro-hormone were measured by tau 3-MSH RIA. The immunoreactive tau 3-MSH in sheep plasma was found to have an apparent molecular weight of approximately 10,000 by gel chromatography through Sephadex G-75, which is similar to the size of the major circulating form of pro-tau-MSH found in human and rat plasma. Daily haemorrhage consistently elevated plasma concentrations of cortisol and pro-tau-MSH. There was no significant difference in the daily responses of either cortisol or pro-tau-MSH when considered individually. However, there was a significant change over the four days in the relationship between the cortisol and pro-tau-MSH responses, as judged by analysis of variance of the difference in daily z-scores of cortisol and pro-tau-MSH. This trend indicated a relative increase in the secretion of pro-tau-MSH from the pituitary compared to the cortisol response, and suggested that repeated exposure to stressful stimuli may alter the pituitary-adrenal-axis.