Reproducibility of plasma catecholamine metabolites in normal subjects.

BACKGROUND: Plasma homovanillic acid (HVA) and methoxy-hydroxy-phenylglycol (MHPG) are often used in repeated measurement designs to assess dopamine and norepinephrine metabolism in clinical research. However, only limited data on the reproducibility of these metabolites are currently available. METHODS: Plasma HVA and MHPG were measured in normal volunteers on five nonconsecutive mornings under fasting conditions and restricted smoking and physical activity. RESULTS: Intraclass correlation coefficients (ICC) for plasma HVA and MHPG across 5 days were determined to be 0.85 and 0.79, respectively. ICC improved to 0.90 for HVA and 0.91 for MHPG when the average of the first 2 days was examined against the average of the last 2 days. CONCLUSIONS: Results suggested that under controlled conditions plasma HVA and MHPG measurements have good reproducibility.

Control of renal factors in plasma homovanillic acid measurements.

To identify and control renal factors affecting plasma homovanillic acid (HVA), a dopamine metabolite and an indicator of brain dopamine activity in clinical research, nine healthy subjects were studied on 5 nonconsecutive days. First study day was the baseline and on the other days base, salt, water, or probenecid loads were given. On each day serial concentrations of HVA and serotonin metabolite 5-hyroxyindoleacetic acid (HIAA), another organic anion, in plasma were measured. Results suggested that base, salt, and water loads did not affect plasma concentrations of either metabolite. Probenecid, which partially blocks renal organic anion transport, induced similar increases in plasma HVA and HIAA. When plasma HVA:HIAA ratio was used to control for the effect of probenecid, differences between baseline and probenecid days were no longer significant. Results suggest that HVA and HIAA are similarly handled by the kidney and that simultaneously measured plasma HIAA could be used to distinguish renal influences in plasma HVA studies.

Influencing immune perturbations by prolonged corticotherapy in the chronic active liver disease.

This paper deals with the influencing of the imbalance of humoral and cellular immunity in chronic active liver disease (CALD) due to prolonged administration of continuous corticotherapy in moderate doses. This paper presents a controlled study carried out in 30 patients with CALD of whom 15 received corticotherapy, while the other 15 only a conventional hepatotropic treatment for a year. The results obtained show, beside a clinical and biological improvement, a positive influence on the immune parameters with a tendency of restoration of immune homeostasis, i.e., an increase of the T total and T1 (suppressing/cytotoxic) lymphocytes in the peripheral blood, with the concomitant decrease of IgG, IgM and circulating immune complexes (CIC). In the control group the changes were insignificant, but sometimes an aggravation of the immune disturbances could be observed. This study confirms the favourable effect of prolonged corticotherapy in CALD and argues for its immune-modulating action.