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Biomedical subjects

A Kayali

Publications and source records attributed to A Kayali.

7 recordsLinked to original sources
PubMed2001

Blood mercury levels of dental students and dentists at a dental school.

OBJECTIVE: To determine the blood mercury levels in dental students and clinical teaching staff in a dental school using amalgam as a restorative material. SETTING: A dental school in Ege University, Turkey surveyed during one academic year. SUBJECTS AND METHODS: Cross-sectional study of groups of dental students (n=92) in years I to V, clinical teachers in restorative dentistry (n=16) and controls (n=14). Mercury concentration was estimated in venous blood samples using a cold vapour atomic absorption method at the commencement and end of the academic year. Daily air mercury levels were determined in clinical and teaching areas by measuring the darkening of palladium chloride discs using spectrophotometry. RESULTS: There were statistically significant increases (p<0.001) in plasma mercury concentration between measurements in all groups at the end of the academic year. Red cell mercury levels were also consistently elevated. Although the highest levels of mercury were recorded in persons working with amalgam, increased levels were also found in subjects working in the teaching classrooms but not with amalgam (controls and first year students). CONCLUSION: Increased mercury levels appeared to be due to background exposure from spillage of mercury and amalgam residues on floors. Increased mercury hygiene and regular control of working atmosphere should be implemented to prevent mercury exposure in the dental pre-clinical laboratory.

Air Pollution, Indoor↗
PubMed1982

Histamine as a ligand in blood plasma. Part 5. Computer simulated distribution of metal histamine complexes in normal blood plasma and discussion of the implications of a possible role of zinc and copper in histamine catabolism.

Previously physiological experiments carried out on mice have proved that copper and zinc can interfere with the pharmacological effects of histamine that lead to anaphylactic shock. A quantitative study of the interactions between essential metal ions and histamine in plasma was thus undertaken. The progressive approach towards a reliable computer-simulated distribution of the histamine-containing plasma species necessitated a large series of physicochemical determinations of the formation constants of the binary and ternary metal complexes involved. The present paper deals with the determination of the formation constants in the zinc-serine, zinc-histamine-serine, zinc-histamine-lysine, copper-serine, copper-histamine-serine, and copper-histamine-valine systems, which were still necessary to reach the reliable simulation required. The subsequent final distribution of histamine in plasma has thus been computed, and interpreted in terms of a possible role for zinc in assisting the histamine catabolism process. Further computer calculations simulating the increase of the zinc concentration in human blood plasma support this interpretation. The antagonizing role of copper against that of zinc has also been examined.

Animals↗
PubMedDate not supplied

Pharmacokinetics of carbamazepine. Part I: A new bioequivalency parameter based on a relative bioavailability trial.

The relative bioavailability of three carbamazepine generics available in Turkey, were investigated in 5 healthy male volunteers. When issuing a license to any drug, FDA stipulates at most a difference of 20% from the reference drug only in peak concentration and AUC (area under the curve). This condition may cause some problems, as two generics of the same drug can yield the same total amount (AUC) and can be accepted as bioequivalent despite different curves of the two drugs. In this study, to compare drugs from the point of view of bioequivalency, we suggest a new calculation method that takes into account ka (absorption rate constant), ke (elimination rate constant), tmax (time to peak), MRT (mean residence time) and AUC. Should this formula be used in comparison of bioequivalency, all the parameters related to the kinetics of drugs will have been taken into account. The suggested parameter is: [formula: see text] However, amongst three carbamazepine generics-Tegretol, Temporol and Karazepin-the most desirable curve is that of Tegretol, while bioavailability values are respectively F = 0.86, 0.93, 0.85 and AUC = 145, 161, 127. The A parameter values are respectively 49.3, 47.2, 42.9.

Adult↗
PubMedDate not supplied

Bioequivalency evaluation by comparison of in vitro dissolution and in vivo absorption using reference equations.

Using in vitro dissolution and in vivo absorption of different generics or batches for an appropriate drug and dosage form, a reference equation of form: ka = a+bkd+dkd2 can be proposed. In the case of availability of standardised in vitro-in vivo data for a specific drug, a Level A a correlation of this type containing experimentally determined a, b, d parameters would serve to predict in vivo absorption phase of the drug. The larger number of batches, the stronger will be the predictive power of these parameters.

Absorption↗
PubMedDate not supplied

An attempt to predict daily erythrocyte lithium fluctuations.

Erythrocyte lithium concentration, which is a better predictor of brain lithium levels than plasma lithium concentrations, possesses the disadvantage of precise hourly determination following the last intake. The variability in RBC lithium accumulation increases as the extracellular lithium concentration increases. This increase is also time dependent and it would be very useful if the pharmacokinetic rate constant were known. Unfortunately, low lithium levels do not allow measurements within confidence intervals. In this work, we tried to determine, in vitro, the kinetic rate constants in erythrocytes of healthy volunteers. Different high lithium loaded plasma-like media were used for an extrapolation procedure of constants allowing the determination of an erythrocyte load constant namely K0 = 0.0161 +/- 0.0005 h-1 at corresponding plasma lithium concentrations. The abnormalities of lithium transport determined by in vitro procedures would be very useful in understanding the etiology of affective illness. Lithium flux pre-controls corrected with this rate constant would be very helpful in enlarging laboratory time management.

Antimanic Agents↗
PubMedDate not supplied

The effect of delayed gastric emptying and absorption on pharmacokinetic parameters of lithium.

Gastrointestinal motility is one of the most important factors than can influence drug absorption from gastrointestinal tract. The aim of the present study was to investigate the effect of delayed gastric emptying and intestinal transit on pharmacokinetic parameters of lithium. Treatment animals were administered an anticholinergic agent (propantheline bromide, 4 mg/kg, p.o.) 10 min before lithium chloride (1.5 mM/kg, p.o.) administration, whereas the control group was administered the same dose of lithium p.o., alone. Plasma lithium levels were measured by flame spectrophotometry and calculated with a computer programme (SIPHAR). Differences detected in AUC, fractionated AUC values, Cmax and tmax suggest that using delayed absorption process, it is possible to prolong by 272% the plateau time of the drug in the therapeutic range and this approach might be an alternative way to prevent some undesirable effects due to peak plasma levels above the maximal therapeutic level. This approach might be more important as an alternative for suitable slow release formulations.

Animals↗