Increased (L+)-lactic acid production in lysozyme-inactivated suspensions of human dental plaque

The effect of lysozyme-inactivation on L(+)-lactic acid (LA) production in dental plaque suspensions was evaluated. From 10 children 24-h plaque was collected and lysozyme activity inhibited by addition of goat antiserum to human lysozyme. Acid production was stimulated by addition of glucose. The results showed significantly increased LA levels (50-150%) in lysozyme-inactivated plaque suspensions from 8 of the subjects compared to untreated controls. The increase in acid production activity was not related to plaque lysozyme levels. The findings indicate that the presence of lysozyme may be limiting on acid production in the early dental plaque.     

Levodopa up-regulates platelet alpha 2-adrenoceptors

Treatment of dogs for 21 days with oral levodopa (100 mg b.i.d.) plus benserazide (25 mg b.i.d.) induced a significant increase in the number of platelet alpha 2-adrenoceptors labelled by [3H] yohimbine with no change in Kd. The rise was maximal at the end of the treatment and remained significant during the month following the cessation of treatment. Plasma catecholamine levels did not vary. Competition experiments showed a low affinity of both dopamine and levodopa for platelet alpha 2-adrenoceptors. These results suggest that levodopa treatment regulates alpha 2-adrenoceptor number in dog platelets.     

Comparison of two analytical procedures for the determination of free urinary catecholamines under the demands of shiftwork experiments

Summary A typical shiftwork experiment was chosen to prove the validity of an automated procedure for the analysis of free noradrenaline and adrenaline in urine. The method consists of a column switching technique with an adsorption/elution clean-up and a reversed phase high performance liquid chromatography followed by chemical reaction detection based on the trihydroxyindole method. The analysis of variance was performed using a second data set obtained by a semi-automated procedure for which the accuracy had already been confirmed. The analysis of covariance showed that for field studies, as well as for laboratory experiments in which the variances contributed by the experiments themselves are greater than 10% rel., the data sets of the two methods provide the same information.Dedicated to Prof. H. Hartkamp, University of Wuppertal, on the occasion of his 60th birthday     

Respiratory function and bronchial reactivity in mill workers

Professional exposure to vegetable dusts affect the respiratory function of the exposed subjects. A previous survey conducted in an industrial flour-mill demonstrated a higher frequency of respiratory symptoms in workers compared to a control group. Ten subjects employed in a work site particularly exposed to dust were studied. Each subject answered a questionnaire and performed on Mondays and Fridays, at the begenning and end of his work shift, a flow volume curve and an isocapnic hyperventilation test. The aerobiology of the professional environment was also measured. We noted: 1) in the flow volume curves: a drop in the FEV₁ during the Monday morning shift, a significant difference between the FEV₁ (p<0.05) and the MMEFR 25–75 (p<0.05) measured at 6 am on Monday and Friday, and between the MMEFR 25–75 values obtained at 12 noon on Monday and Friday (p<0.05). 2) after isocapnic hyperventilation, a significant drop in the MMEFR 25–75 at 6 am on Monday (p<0.01) and in the FEV₁ and MMEFR 25–75 at 12 noon on Mondays (p<0.05), a significant drop in the FEV₁ at 1 pm on Monday (p<0.01).     

ACETALDEHYDE ADDUCTS WITH HAEMOGLOBIN: DETERMINATION OF ACETALDEHYDE RELEASED FROM HAEMOGLOBIN BY ACID HYDROLYSIS

Acetaldehyde, the first metabolite of ethanol, reacts with haemoglobinin vitro to produce acetaldehyde—haemoglobin adducts.Some clinical studies on the minor haemoglobins have suggestedthat these adducts may be formed in people abusing alcohol.Under hydrolysis of haemoglobin, with oxalic acid at 100°Cin sealed vials, some acetaldehyde was released and then specificallydetermined by HPLC. The kinetics of hydrolysis were studiedusing haemoglobin previously labelled with ¹⁴[C] acetaldehyde.The maximum liberation of ¹⁴[C] acetaldehyde was obtained after3 hr 30 min hydrolysis and this time factor was then utilizedin the analysis of alcoholic and control haemoglobin. Thus,we have confirmed the formation of acetaldehyde haemoglobinadducts in vivo. It must be noted that the released acetaldehydecorresponds only to an index of the stable adducts. The levelswere higher in alcoholics than in controls (1.417±0.171and 1.295±0.139 nmol/mg Hb, respectively, P<0.001).In conclusion, this marker is not a convenient tool for themonitoring of alcohol exposure levels because of the low differencesbetween alcoholic and control haemoglobins.