Evaluation of the accuracy of enzymatically determined carrier status for Krabbe disease by DNA-based testing.
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Case-Control Studies↗
Biomedical subjects
E Randell
Publications and source records attributed to E Randell.
Changes in serum carbohydrate-deficient transferrin and gammaglutamyl transferase after moderate wine consumption in healthy males.
Serum carbohydrate-deficient transferrin (CDT) concentrations and gammaglutamyl transferase (GGT) activities were measured in the fasting serum of healthy male subjects before and after 4 weeks consumption each day of 375 ml wine or 500 ml grape juice. After wine consumption, serum CDT concentrations rose in 38 of 48 individual test procedures, and the mean +/- SEM increased from 17.8 +/- 0.86 u/l to 20.9 +/- 1.14 u/l (t0 = 4.66; P < 0.001). Serum GGT activity rose in 35 of these test procedures, and the mean +/- SEM increased from 19.6 +/- 1.40 u/l to 22.3 +/- 1.79 u/l (t0 = 3.58; P < 0.001). When wine consumption was followed by 2 weeks of abstinence from alcohol, significant reductions in both CDT and GGT were noted, virtually reaching baseline levels. No significant change in either index occurred after 4 weeks of consuming grape juice. The correlation between CDT and GGT was rather low, suggesting that their responses to alcohol occur by different mechanisms. The results indicate that the response of CDT to alcohol dose is continuous, and that even moderate consumption can cause significant elevations in a healthy population.
Adult↗
Evidence for phosphatidylcholine hydrolysis by phospholipase C in rat platelets.
Production of [3H]1,2-dipalmitoylglycerol ([3H]DAG) from 1-palmitoyl-2-[9,10-3H]palmitoyl-sn-glycero-3-phosphocholine and [3H]phosphorylcholine from 1,2-dipalmitoyl-sn-glycero-3-[Me-3H]phosphocholine was studied using sonicated rat platelets. The formation of [3H]DAG and [3H]phosphorylcholine occurred at a comparable rate. [3H]Phosphorylcholine formation was dependent on the concentration of the substrate, platelet sonicates and calcium in the incubation medium. The [3H]phosphorylcholine formation increased in presence of 0.01% deoxycholate and 0.01% Triton X-100. The phosphatidylcholine-phospholipase C (PC-PLC) in the platelet sonicates was recovered in both the supernatant and particulate fractions obtained after ultracentrifugation at 105,000 x g for 1 h. The PC-PLC activity in both fractions was inhibited by 2 mM EDTA. In the presence of 0.01% deoxycholate and 0.01% Triton X-100 the activity in the particulate fraction increased compared to the activity in the supernatant, which was inhibited by 0.01% Triton X-100. The pH optima for PC-PLC in both fractions was between pH 7.2 and 7.6. PC-PLC activity was also found in rabbit and human platelet sonicates, but the activity was significantly lower than in rat platelet sonicates. There was no evidence to suggest presence of phosphatidylcholine-specific phospholipase D activity in rat sonicated platelets. This data, therefore, provides direct evidence for the presence of PC-PLC activity in rat platelets.
Animals↗
In vitro inhibition of rat platelet aggregation by ochratoxin A.
The mycotoxin ochratoxin A (OA) consists of 5-chloro-3-methyl-3,4-dihydro-8-hydroxyisocoumarin moiety linked by an amide bond to beta-L-phenylalanine. When added to washed rat platelets in vitro, OA caused a dose-dependent inhibition of aggregation induced by agonists such as adenosine diphosphate (ADP) or thrombin. The aggregatory response induced by prior addition of an agonist was also reversed in a dose-dependent manner by OA. Inhibition of aggregation appeared to be irreversible since exposure of platelets to OA followed by several washings removed most of the mycotoxin associated with the platelets but did not diminish the inhibitory response. Serotonin secretion from dense granules and arachidonic acid release from membrane phospholipid (especially phosphatidylcholine) as well as its further metabolism were also inhibited by OA. These results suggest that a disruption of the platelet plasma membrane structure by OA is probably responsible for inhibition of the primary and secondary phases of aggregation.
Animals↗
Binding of rat serum phosphorylcholine binding protein to platelets.
Rat serum phosphorylcholine binding protein (PCBP), a normal component of rat serum, inhibits in vitro aggregation of rat, rabbit and human platelets by interacting with platelets. In the present study, we have demonstrated the calcium-dependent, specific and saturable binding of 125I-PCBP to rat, rabbit and human platelets. Scatchard analysis of the binding data reveal a class of specific high-affinity binding sites with Kd values of 45.2 +/- 14.9, 26.1 +/- 8.3 and 32.2 +/- 9.9 nM on rat, rabbit and human platelets, respectively. These platelets also expressed a high capacity for binding to 125I-PCBP. The binding of 125I-PCBP to platelets was calcium- and time-dependent, and could be inhibited by phosphorylcholine (IC50 = 5.6 microM). Occupation of these binding sites by PCBP may be responsible for inhibition of platelet aggregation.
Animals↗
Interaction between rat serum phosphorylcholine binding protein and platelet activating factor.
The binding of rat serum phosphorylcholine binding protein (PCBP) to platelet activating factor (PAF) has been demonstrated using a HPLC-gel filtration technique. The bulk of the bound [3H]-PAF eluted with a higher molecular weight species of PCBP, possibly an aggregated form of PCBP. A smaller amount of [3H]-PAF co-eluted with the major monomeric species of PCBP. Formation of the PCBP-PAF complex was calcium dependent and could be inhibited by phosphorylcholine, suggesting the involvement of the phosphorylcholine binding site on PCBP. Binding of albumin and alpha 1-acid glycoprotein to PAF was not affected by phosphorylcholine or calcium. The specificity of this binding may explain the inhibitory effect of PCBP and related phosphorylcholine binding proteins on PAF induced aggregation of platelets.
Animals↗
Effect of rat phosphorylcholine-binding protein on platelet aggregation.
Rat serum phosphorylcholine-binding protein (PCBP), also referred to as rat C-reactive protein, is present in serum under normal physiological conditions. In the present study, PCBP is shown to inhibit, in a dose-dependent manner, ADP- and platelet-activating factor (PAF)-induced platelet aggregation, using either washed rat platelets or platelet-rich plasma from rats or humans. Rat platelets, as expected, were refractory to aggregation by PAF. However, when rabbit antiserum against PCBP was added to rat platelet-rich plasma, it resulted in aggregation of platelets by PAF. PCBP also inhibited the PAF-induced aggregation of human platelets in a dose-dependent manner. The inhibition of ADP-induced platelet aggregation by PCBP was reversed by adding phosphorylcholine. Our results suggest that PCBP present in rat serum could be the cause of the refractory response of rat plasma to PAF. It is possible that PCBP inhibits platelet aggregation by binding to the platelet surface phospholipids.
Adenosine Diphosphate↗