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Biomedical subjects

G Papeschi

Publications and source records attributed to G Papeschi.

11 recordsLinked to original sources
PubMed1990

Determination of flubendazole in pharmaceutical dosage forms by differential pulse polarography and UV spectroscopy.

A precise and accurate differential pulse polarographic method was developed for the determination of flubendazole in dosage forms without any prior extraction procedure of interference from the other stated ingredients. A UV spectroscopic procedure was also described and used as reference method. Analyses were generally performed at the 4 micrograms ml-1 flubendazole level. Flubendazole or its dosage forms were dissolved in 70% perchloric acid and diluted with a pH 2.6 sodium phosphate-citric acid buffer as polarographic supporting electrolyte or spectrophotometric solvent. The peak potential occurred at about -0.9 V (vs. Ag/AgCl reference electrode), depending on the pH of the assayed solution. The irreversible electrochemical reduction involved the transfer of two electrons. The UV absorption spectrum showed a sharp maximum at 237 nm with a specific extinction coefficient of 886. No advantage was found in the use of first and second-order derivative spectrophotometry.

Indicators and Reagents↗
PubMed1989

Determination of isosorbide-5-mononitrate in tablets by differential pulse polarography.

A differential pulse polarographic method requiring little sample separation was developed for the determination of isosorbide-5-mononitrate in tablet dosage form with the standard addition technique and without interference from common excipients. Britton-Welford buffer (pH 3.0) was used as the supporting electrolyte, the single peak occurring at -0.36 V vs. a reference Ag/AgCl electrode. The irreversible, diffusion controlled, two-electron reduction process at the dropping mercury electrode permits a precise and accurate determination of the active ingredient in the 0.4-20 microgram/ml concentration range.

Indicators and Reagents↗
PubMed1978

Preliminary experience with the pH-triggered pacemaker.

A cardiac pacemaker capable of responding to blood acidosis by change in its stimulation rate allows adjustment to a patient's metabolic needs. The blood pH is sensed by an iridium oxide electrode in the right atrium. During exercise, the venous pH decreases and the paced ventricular rate increases. If acidosis persists, the paced rate gradually returns to baseline and reaches it after about 70 minutes. A pH-triggered pacemaker has been implanted in a 72-year-old male. The pacemaker remained responsive one year after implant, increasing rate during exercise, cold pressor stress, ischemia of the arms and emotional stress.

Aged↗
PubMed1978

[Clinical and biological aspects in patient with pH-triggered implanted pacemaker (author's transl)].

The Authors have selected the variations of blood pH to drive the pacing rate according to the new biological balance created by exercise. The clinical tests performed on the patients who have had a pH-triggered pacemaker implanted one year previously demonstrated that: a) during physical exercise there is an increase of cardiac rate triggered by the pacemaker, comparable with that noted when sinus rhythm is present; b) situations causing an increased production of cathecolamines and thus a pH variation--Cold Pressor Test, Ischaemic Test, as well as emotional stress--cause an increase of the stimulation rate of pH triggered pacemaker.

Blood↗
PubMed1977

[Scanning electron microscopy study of rat lung tissue].

Parts of rat lung tissue have been examined by means of a scanning electron microscope after either chemical or physical fixage. Chemical fixage produces retraction on the tissue structures and the alveoles appear of irregular shape. Physical fixage gives the possibility to observe lung morphology without distorsions; details reproduced are in this case very clear and in a shape which appears very close to the original conditions.

Animals↗
PubMed1976

Use of an iridium electrode for direct measurements of pI of proteins after isoelectric focusing in polyacrylamide gel.

The use of an iridium microelectrode 0.5 mm in diameter is proposed for measuring the pH gradient in polyacrylamide gels after isoelectric focusing. The electrode exhibits a perfectly linear potential/pH relationship; thus it can be used directly in conjunction with a pH meter using the pH scale for readings. pH equilibrium values are rapidly reached (10-15 s) and pI determinations are obtainable with good accuracy (better than 0.1 pH).

Calorimetry↗
PubMed1976

[Effects of citidine diphosphocholine (citicholine) and phospholipids on the elastic properties of the lung and on the physico-chemical properties of the irrigation liquid].

The effect of citidin-diphosphocholine and of phospholipids treatments on the elastic properties as well as on the washing liquid physical-chemical properties of rat lungs is studied. Significant increase of the compliance and decrease of the tendency to collapse of the airways are observed after treatment with citidin-diphosphocholine.

Animals↗