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Biomedical subjects

J Ekstrand

Publications and source records attributed to J Ekstrand.

At least 145 records · Page 8Linked to original sources
PubMed1982

Fluoride pharmacokinetics in the domestic pig.

Plasma fluoride concentrations were studied in 11 pigs following single oral or intravenous doses of fluoride. The results showed a less-than-20% bioavailability of fluoride when administered with calcium-rich food. Pharmacokinetic analyses showed that the plasma half-life varied from 0.6 to 1.4 h, depending on diet and route of fluoride administration. These data are comparable to those reported for man, and thus illustrate the suitability of the pig for studies of effects of fluoride on hard tissues.

Animals↗
PubMed1982

Lower extremity goniometric measurements: a study to determine their reliability.

Two series of healthy men were measured for range of passive motion of hip flexion, hip extension, hip abduction, knee flexion, and ankle dorsiflexion with the knee extended and flexed. Hip abduction was measured with a specially constructed double protractor goniometer, and the other movements were gauged with a flexometer. In series A measurements were based upon a commonly used clinical method. The intratester interassay coefficient of variation in series A was 7.5 +/- 2.9%, which corresponded well with other reports. In series B posture and measuring procedures were rigidly standardized by better fixation and by identification and marking of anatomical landmarks. The interassay coefficient of variation in series B was reduced to 1.9 +/- 0.7%. Range of motion measurement was repeated accurately by the same tester with methods requiring careful measurement technique but no elaborate equipment.

Ankle Joint↗
PubMed1981

Renal fluoride excretion and plasma fluoride levels during and after enflurane anesthesia are dependent on urinary pH.

To determine the effects of urinary pH on fluoride ion excretion and the resulting plasma fluoride concentration during and after enflurane anesthesia, renal function, plasma inorganic fluoride levels, and fluoride excretion were studied in two groups of patients pretreated with either NH4Cl or acetazolamide to produce acidic or alkaline urine, respectively. During anesthesia, urinary flow rate, inulin clearance (Cin) and para-aminohippurate (PAH) clearance (CPAH) were 7, 61, and 43 per cent of control values in the acidic-urine group and 22, 74, and 57 per cent of control values in the alkaline-urine group, respectively. Fractional fluoride clearances (CF/CIN) during anesthesia and operation were 0.06 +/- 0.05 in the acidic-urine group (urinary pH 5.08) and 0.68 +/- 0.23 in the alkaline-urine group (urinary pH 8.16). Values of total fluoride excretion during the same period were 0.06 +/- 0.04 mg and 0.87 +/- 0.29 mg, respectively. Mean maximal plasma levels of fluoride were 26.3 +/- 7.3 microM in the acidic-urine group and 13.5 +/- 2.4 microM in the alkaline-urine group. The differences between groups in fluoride clearance, fluoride excretion, and plasma fluoride levels were all statistically significant. The data clearly show that renal fluoride clearance is closely related to urinary pH.

Acetazolamide↗
PubMed1981

Dopamine infusion in man. Plasma catecholamine levels and pharmacokinetics.

Dopamine is widely used in the treatment of hypotensive conditions and/or impending renal failure, but the plasma levels of dopamine and other catecholamines in association with dopamine infusion are not known. Plasma catecholamines and dopamine pharmacokinetics during and after dopamine infusion were therefore studied in man. Two and 5 micrograms x kg-1 x min-1 of dopamine were infused for 30 min in two groups of five patients. Dose-dependent mean steady state levels with fairly large interindividual variations were reached within 5 min. Elimination of dopamine from plasma after termination of infusion had a biphasic course with t 1/2 alpha around 1 min and t 1/2 beta about 9 min in both groups. Noradrenaline plasma levels and blood pressure increased significantly in the 5 micrograms group. It is suggested that the vasoconstriction with deleterious effects on tissue perfusion, seen in conjunction with high-dose dopamine infusion, may be due to increased noradrenaline levels.

Adult↗
PubMed1981

Relationship between plasma, dentin and bone fluoride concentrations in rats following long-term fluoride administration.

A detailed knowledge of fluoride (F) pharmacokinetics is necessary if its pharmacologic and toxicologic effects are to be adequately understood. In the present study plasma F concentrations have been analysed using repeated blood samples taken from the ethmoidal sinus of rats given 25, 50, 100 and 150 p.p.m. F in drinking water ad libitum for 79 days. A close relationship between the F-concentration in the drinking water and plasma F concentrations was found. When the administration of F was stopped, a rapid decline in plasma F concentration was noted during 48 hrs in all groups. The plasma F concentrations in the 25 p.p.m. group returned to preexperimental levels but remained elevated in the other groups. The F concentrations of dentin and bone were determined and calculated on a dry fat free basis. The results show that there was a close relationship between plasma, bone and dentin concentrations.

Animals↗
PubMed1980

Fluoride pharmacokinetics during acid-base balance changes in man.

Five healthy subjects were each given fluoride 3.0 mg (F) as sodium fluoride tablets on two occasions - during production of acid urine, induced by giving NH4Cl, and during production of alkaline urine obtained by giving NaHCO3. Frequent plasma and urine samples were taken up to 12 h and were analyzed with a F- sensitive electrode. Control experiments without F administrations were also performed to permit calculation of net F concentration in plasma and urine. The urine F excretion was lower during acid than alkaline diuresis. Pharmacokinetic analysis of the net plasma F concentrations showed that the apparent plasma half-life of F was longer when urine was acid (4.3 +/- 0.6h: SD; n = 5) than when it was alkaline (2.4 +/- 0.4h). This could be explained by changes in the renal clearance of F, which was always lower with an acid (61.5 +/- 8.1 ml/min) than an alkaline (97.8 +/- 10.4 ml/min) urine. The apparent extra-renal clearance, which mainly represents clearance to the bone-pool, was also significantly higher during production of alkaline (109.2 +/- 20.2 ml/min) than of acid (86.3 +/- 21.3 ml/min) urine. It is suggested, that increased reabsorption of non-ionic hydrogen fluoride (HF) is responsible for the decreased renal clearance during acidic conditions.

Acid-Base Imbalance↗
PubMed1980

Renal fluoride excretion during and after enflurane anaesthesia: dependency on spontaneous urinary pH-variations.

Renal function, fluoride formation and excretion were studied in seven patients during and after enflurane anaesthesia and surgery. The mean maximal plasma level of fluoride was 17.4 microM. It was reached 2 h after termination of anaesthesia. Pre-operatively, fraction fluoride clearance (CF/CIn) was 0.31. During anaesthesia and surgery it decreased to 0.10 and postoperatively rose to 0.55 and 0.77 during two consecutive measurement periods. There was a highly significant correlation (P less than 0.001) between this increase in CF/CIn and the simultaneous rise in urinary pH between the two periods (r = 0.91).

Adult↗
PubMed1980

Subcutaneously implanted alginate as a continuous-release source of fluoride.

The fluoride concentrations of seven brands of alginate ranged from 8600 to 30,500 ppm. In acute and chronic in vivo studies, fluoride was continuously released from subcutaneously implanted alginate cylinders for up to three weeks. This technique is a simple and economical method for elevating soft and hard tissue fluoride levels.

Alginates↗
PubMed1980

Systemic absorption of fluoride from alginate impression material in humans.

Thirty minutes after routine alginate impressions in five adult subjects, plasma fluoride levels increased by an average of 2.6 times over control values. Urinary fluoride excretion rates increased approximately 2.9 times during the first two hours after the impressions. Average whole saliva fluoride levels at 15 minutes were over 100 times the average control concentration. When small amounts of alginate were deliberately ingested, plasma fluoride levels and urinary excretion rates increased sharply.

Absorption↗
PubMed1979

Influence of milk products on fluoride bioavailability in man.

The effect of milk products on the gastrointestinal absorption of fluoride from sodium fluoride tablets was studied in five healthy subjects. Two different diets were tested: (1) 250 ml standardized milk (3% fat) and (2) 500 ml of milk, 3 pieces of white bread with cheese and 150 ml of yoghurt. The 100% bioavailability of sodium fluoride tablets during fasting was greatly decreased by coadministration of milk products: with Diet 1 the absolute bioavailability calculated from combined plasma and urine data was in the range 50--79% and with Diet 2 it ranged from 50--71%. It is suggested that the decreased bioavailability produced by dairy products should be taken into account when establishing flouride dosage regimens for prophylaxis of caries.

Adult↗