Electrochemical biosensors for extracorporeal measurements.
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Biosensing Techniques↗
Biomedical subjects
G Palleschi
Publications and source records attributed to G Palleschi.
Lactate and glucose electrochemical biosensors for the evaluation of the aerobic and anaerobic threshold in runners.
Lactate and glucose are measured in whole blood of athletes running on a treadmill by using two extracorporeal electrochemical biosensors. The lactate sensor was fixed to an endocrine artificial pancreas (Betalike) which had been used in previous extracorporeal experiments. The lactate sensor gave a signal which resulted in a well defined curve that allowed the evaluation of the aerobic as well as the anaerobic threshold. The results obtained with the glucose sensor supported the theory that muscle anaerobic glycolysis is dependent on muscle glycogen rather than on blood glucose.
Adult↗
Determination of serum cholinesterase activity and dibucaine numbers by an amperometric choline sensor.
Serum cholinesterase activity and the dibucaine numbers have been determined by using a hydrogen peroxide electrode and the enzyme choline oxidase immobilized on a nylon net. The analysis procedure is extremely simple and very fast allowing 30 cholinesterase determinations per hour. Both cholinesterase activity and dibucaine number measurements could be performed in 5 min and by using serum samples of only 10 microliters. When used in sera the probe showed no interference from electroactive compounds present in blood, and also showed good stability and reproducibility. These features make this sensor appropriate for continuous extracorporeal circuit blood monitoring of succinylcholine during surgery.
Alcohol Oxidoreductases↗
Extracorporeal determination of glucose, lactate and potassium with electrochemical biosensors.
Glucose, lactate and potassium ions have been continuously measured in whole blood by using two extracorporeal electrochemical biosensors and a new flow through potassium electrode. For experiments involving the "glucose clamp", lactate and potassium electrodes have been connected in series to an endocrine artificial pancreas "Betalike" properly modified. The same artificial pancreas has been used in experiments measuring the anaerobic threshold (AT) by continuous monitoring of lactate in athletes. In this case glucose and lactate sensors were connected in series for continuous measurement of both metabolites in blood in real time. The results are in agreement with the biochemical pathways involving such metabolites.
Adult↗
A study of interferences in glucose measurements in blood by hydrogen peroxide based glucose probes.
The main blood constituents which could interfere in clinical glucose measurements using a hydrogen peroxide based glucose electrode have been investigated using several different membranes and constant and sweeping potentials. Both diluted and whole undiluted sera were investigated. With a 3500 molecular weight cut-off (MWCO) membrane, acetaminophen, cysteine, and ascorbic acid can interfere. With a 100 MWCO membrane, only acetaminophen interfered.
Blood Glucose↗
Determination of choline-containing phospholipids in human bile and serum by a new enzyme sensor.
A simple method for direct determination both of choline and lecithin (phosphatidylcholine) in human bile and blood sera was developed. An enzyme electrode, based on immobilized choline oxidase on nylon net and an oxygen Clark electrode was assembled. Phosphatidylcholine can be determined by use of phospholipase D as hydrolyzing agent. Reliable results were obtained in the case of determination of lecithin and choline in bile samples.
Alcohol Oxidoreductases↗
An L-lactate sensor with immobilized enzyme for use in in vivo studies with an endocrine artificial pancreas.
We report the features of a sensor for determining L-lactate. An oxygen sensor, coupled to a nylon net with chemically bound L-lactate oxidase (EC 1.1.3.2), is inserted into an artificial pancreas (Biostator, Miles) "downstream" from the glucose sensor. We used the sensor to continuously monitor the L-lactate concentration in blood after a "glucose clamp" experiment with a diabetic patient. L-Lactate determinations in blood drawn from the patient every 15 min agreed well with results obtained by use of the L-lactate sensor.
Enzymes, Immobilized↗
Lecithin determination in foods and drugs by an amperometric enzymatic sensor.
A new enzymatic-amperometric method for the determination of lecithin as an additive in foods and as a component of commercial drugs is proposed. The method is based on a detector realized with two enzymes, choline oxidase and phospholipase D, the former immobilized, the latter free in solution, and by an oxygen Clark electrode. The experimental conditions were investigated in order to obtain wide applications with different samples. Extraction or dissolution of the samples in ethanol proved satisfactory. The precision of the method was found to be about 1.5%, inaccuracy less than or equal to 4%. Correlation between the proposed enzymatic-amperometric method and an enzymatic-spectrophotometric reference method was satisfactory.
Alcohol Oxidoreductases↗
Molecular detection of microsatellite instability in basal cell carcinoma.
Several studies have shown that the presence of genetic instability can be associated to carcinogenesis process. The detection of microsatellite instability (MI) that consists of an expansion and/or deletion of DNA within repeat sequences, may constitute a sensitive marker for the presence of gene mutations. A series of 18 basal cell carcinoma (BCC) consecutive patients was examined for the presence of alteration in 12 DNA microsatellite markers, in order to better understand the molecular significance of MI in the genesis and progression of BCC. Molecular alterations were detected in 6 out of 12 analyzed microsatellite loci. Five out of 18 BCC samples showed loss of heterozygosity at chromosome loci localized in the vicinity of the tumor suppressor genes, whereas six out of 18 BCC patients presented at least one altered microsatellite (instability). We demonstrated molecular genetic alterations at 2p16 locus, in the proximity of MSH2 gene and 17p21, in the proximity of the p53 gene. These data validate and confirm a role of MI in genesis and progression of BCC, by analysis of markers localized at specific chromosome region in proximity of oncogenes and tumor suppressor genes.
Adult↗