Determination of 3,4-dihydroxyphenylalanine (DOPA) in plasma and cerebrospinal fluid by high performance liquid chromatography with electrochemical detection

We report a reliable method for determining DOPA levels in plasma and cerebrospinal fluid. The method is based on complete conversion of DOPA to dopamine and quantification by HPLC-ECD of the dopamine formed. Lower limit of detection was 0.5 nmol/l. No differences in plasma DOPA levels were found between normal children (0-15 yr, n = 60), normal adults (n = 39) and patients with essential hypertension (n = 40) or Parkinson's disease (no DOPA therapy, n = 30). In normal individuals and in patients with essential hypertension venous plasma levels were higher than arterial levels (10.2 vs 9.3 nmol/l, p less than 0.001, V/A ratio 1.11 (SD 0.08), n = 15). Sympathetic stimuli (standing, tilting, bicycle exercise, tyramine) did not influence DOPA levels. In untreated depressed patients (n = 10) and in non-parkinsonian neurological patients (n = 12) cerebrospinal fluid levels of DOPA were 4.5 (SD 2.4) and 5.2 (SD 1.3) nmol/l respectively. A direct method for the measurement of DOPA by HPLC-ECD after deproteinization of plasma is also described and compared with the conversion method. Good agreement was found when plasma DOPA levels exceeded 0.25 mumol/l (y(conversion method) = 0.943x (direct method) + 0.118; n = 60; r = 0.985). The direct method, because of greater simplicity and the possibility of simultaneous measurement of the DOPA metabolite 3-O-methyldopa, is the method of choice with plasma samples from DOPA-treated patients. In non-DOPA treated individuals the conversion method is superior and has proved to be an accurate and sensitive method for the determination of DOPA levels in plasma and cerebrospinal fluid.     

The effect of ethanol intake on tendon healing: a histological and biomechanical study in a rat model

Introduction  

Ethanol has a suppressive effect on inflammation and the immune system, but the effect of ethanol on tendon healing in vivo has not been studied. The purpose of this study was to investigate the histological and biomechanical effects of ethanol intake on tendon healing in a rat tendon injury model.     

Some new clinical applications of rhinomanometry

Clinical applications of active anterior rhinomanometry of the oscillation type had been carried out for the purposes other than the conventional uses of rhinomanometry. 1. Effect of acupuncture upon the nasal resistance to airflow: Among 8 acupuncture points which were recorded in Chinese traditional medical literatures as effective for improving nasal breathing, Ingxiang point had been proved to possess definite effect of lowering the nasal resistance to air-flow in patients with congestion of nasal mucosa, whereas in other acupuncture points this effect was not certain. 2. The severity of snoring before and after treatment could be determined objectively by the measurement of nasal resistance to air-flow and the breathing pattern of the patient.