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PubMed1993

[Determination of heavy metals in samples of herbal drugs using differential pulse polarography].

The contamination of the environment requires the content of heavy metals in medicinal plants to be limited and controlled. The present paper aims to demonstrate the possibilities of application and advantages of a modern polarographic method, differential pulse chromatography (DPP), in the identification and determination of heavy metals in the plant material. In the plant drugs Flos chamomillae and Flos calendulae, the heavy metals Pb, Cd, Ni, Zn, Cu and Fe were identified and determined. The World Health Organization (WHO) indicated Pb, Cd and Ni as dangerous toxic trace elements.

Metals↗
PubMed1993

Retinal blood flow by hydrogen clearance polarography in the streptozotocin-induced diabetic rat.

PURPOSE: The authors compared retinal blood flow in rats after 5 weeks of streptozotocin (STZ)-induced diabetes with that in age-matched control animals. METHODS: The flow measurements were based on the hydrogen clearance technique and the intraocular placement microelectrodes at the surface of the retina. The hydrogen was delivered by bolus injection (100 microliters) of hydrogen-saturated saline into the ipsilateral carotid artery using a cannula through the lingual artery. The rats were anesthetized and artificially ventilated. Care was taken to match the systemic blood pressure and blood gases in the two groups. RESULTS: The mean retinal blood flow in the STZ group after 5-6 weeks duration of hyperglycemia was 487 +/- 59 ml/min/100g (standard error) compared with 330 +/- 16 ml/min/100 g in the age-matched controls. The variation in retinal blood flow was far more pronounced in the STZ group, even in different locations in the same eye. Changes in fundus appearance were also noted, with second-order arterioles being more apparent and the retina more "pinkish" in appearance in the STZ animals. CONCLUSIONS: The mean retinal blood flow in the region of retina studied in the two groups was significantly higher in the STZ animals than in age-matched controls. The increased heterogeneity of retinal blood flow may reflect a disruption to the normal blood flow control mechanisms in the retina after only 5 weeks of STZ-induced diabetes.

Animals↗
PubMed1996

Simultaneous determination of In(III) and Cd(II) by differential pulse polarography in the presence of poly beta-cyclodextrin.

The difference in the peak potentials of In(III) and Cd(II), whose reduction potentials are very close to each other, becomes large in the presence of poly beta-cyclodextrin in sodium perchlorate medium. The relationships between the peak currents for these two ions and their concentrations are linear, suggesting that the simultaneous determination of the ions is possible in the presence of this reagent.

Journal Article↗
PubMed1983

Continuous direct tissue oxygen tension measurement by a new method using an implantable silastic tonometer and oxygen polarography.

A new method of tissue oxygen tension measurement that is suitable for human use has been described. An implanted Silastic tube tonometer is combined with polarographic oxygen electrodes. The techniques of preparation, insertion, and measurement have been described. The advantages and disadvantages of this method have been considered in relation to established methods of tissue oxygen tension measurement. The method is suitable for clinical use and can be used to aid clinical decision-making.

Oxygen↗
PubMed1986

Direct determination of zinc in insulin preparations by differential pulse polarography.

A rapid and direct differential pulse polarographic method for the determination of zine in insulin preparations is described. Optimum conditions were studied using 0.2 M acetate buffer (pH 4.1) as the supporting electrolyte. Agreement between the results by direct analysis and those by the procedure involving pressurized digestion was satisfactory.

Journal Article↗
PubMed2002

Study of Cd2+ complexation by the glutathione fragments Cys-Gly (CG) and gamma-Glu-Cys (gamma-EC) by differential pulse polarography.

A differential pulse polarographic study of the Cd2+/gamma-Glu-Cys and Cd2+/Cys-Gly systems assisted by the alternating least-squares multivariate curve resolution (MCR-ALS) method was carried out to obtain a better understanding of the different metal affinities of the complexation sites on glutathione (GSH). The simultaneous analysis of the titration of peptide with metal and of metal with peptide allowed the resolution of the Cd2+/Cys-Gly system, whereas in the analysis of the Cd2+/gamma-Glu-Cys system the analysis of a single titration experiment was sufficient. The analysis of the shape of the resulting pure voltammograms and concentration profiles of the resolved components suggested the presence of two different types of bound Cd2+ in the two systems considered, that could be attributed to Cd2+ bound to one or two sulfur atoms to form complexes of stoichiometry 1:1 and 1:2. respectively.

Journal Article↗
PubMed1976

Distribution of myocardial blood flow measured by hydrogen polarography.

Distribution of myocardial blood flow was studied by polarographic recording of hydrogen desaturation in open chest dogs. Flow was measured during normal cardiac activity, reactive hyperemia following 60 seconds of coronary artery occlusion, and left ventricular hypertension produced by either partial supravalvular aortic occlusion or subvalvular outflow constriction. During normal cardiac function, blood flows in the subepicardium and subendocardium were approximately equal. Reactive hyperemia increased flow to both the subepicardium and subendocardium. Left ventricular hypertension decreased subendocardial flow relative to subepicardial flow in proportion to the degree of hypertension. Marked supravalvular obstruction with ventricular hypertension reduced subendocardial flow to two-thirds that of subepicardial flow. This decrease was further accentuated when the left ventricular end diastolic pressure was elevated.

Animals↗