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Biomedical subjects

P Netter

Publications and source records attributed to P Netter.

At least 253 records · Page 14Linked to original sources
PubMed1988

Effects of changes in brain 5-HT activity on indicators of cortical arousal.

Clinical studies on fluoxetine have reported occasional symptoms of increased fatigue in depressed patients. On the other hand, experimental studies in healthy subjects have demonstrated evidence for fluoxetine-induced increases in cortical arousal. The present placebo-controlled study with 24 healthy subjects was designed to answer the following questions: Does fluoxetine increase measures of cortical arousal and decrease feelings of alertness, and does the 5HT2 receptor blocker ritanserin produce inverse effects to fluoxetine? Analyses of covariance revealed the following results: Fluoxetine produced a slight increase, ritanserin a marked decrease in critical flicker fusion frequency. Time perception was slightly improved by both drugs. Self-ratings on alertness and energy were significantly reduced by both fluoxetine and ritanserin as compared to placebo. Effects for fatigue were increased accordingly. Possible underlying neurophysiological mechanisms and specificity of the effects for cortical as opposed to limbic arousal will be discussed.

Adult↗
PubMed1987

Total and free ketoprofen in serum and synovial fluid after intramuscular injection.

Free and total ketoprofen levels in serum and synovial fluid were determined in 37 patients after a single intramuscular injection of ketoprofen, 100 mg. Free drug was separated by equilibrium dialysis. Ketoprofen was assayed by HPLC. Ketoprofen penetrated into the joints rapidly and significant concentrations were found at 15 minutes. The equilibrium time was about 3 1/2 hours. The AUC for total ketoprofen was greater in serum than in synovial fluid. On the other hand, the free fraction AUC in the serum and synovial fluid were quite similar. The mean residence time in the joint was about three times that in the systemic circulation. Ketoprofen was strongly bound to proteins and the percentage of free ketoprofen was not significantly different between serum and synovial fluid. These results provide a possible explanation for duration of the therapeutic effect of ketoprofen despite the short elimination half-life from the serum.

Adolescent↗
PubMed1987

Clinical pharmacokinetics of D-penicillamine.

Penicillamine exists as 2 stereoisomers, but only the D-isomer is used therapeutically. Its chemical reactivity derives from its functional groups, of which the thiol group seems the most important. It is difficult to determine penicillamine in biological fluids because of its instability, the presence of endogenous compounds with a thiol function, and the various chemical forms in which it occurs, namely reduced free penicillamine, penicillamine bound to proteins, and internal (P-S-S-P) and mixed (P-S-S-C) disulphides. The earliest assay methods (colourimetry, isotopic methods, gas-phase chromatography) were neither sensitive nor specific. High performance liquid chromatography with electrochemical detection has led to a more specific assay for D-penicillamine, with detection based on either derivatisation reactions or on electro-oxidisation of the thiol function. With dual-electrode detectors (Au/Hg) disulphides can be assayed directly. D-penicillamine is absorbed rapidly but incompletely (40 to 70%) in the intestine, with wide interindividual variations. Food, antacids and, in particular, iron reduce absorption of the drug. Its bioavailability is also dramatically decreased in patients with malabsorption states. The peak plasma concentration occurs at 1 to 3 hours after ingestion, regardless of dose, and is of the order of 1 to 2 mg/L after an oral dose of 250 mg; some investigators have reported a double peak in plasma, which is probably not due to an enterohepatic cycle. The concentration in plasma then decreases rapidly, generally following a biphasic curve. When long term treatment is discontinued, there is a slow elimination phase lasting 4 to 6 days, which suggests that there is a 'deep compartment' or 'slow pool of the drug reversibly bound to tissues', particularly the skin. This may explain the persistence of its therapeutic effect and the occurrence of undesirable side effects after treatment has been stopped. During long term treatment plasma concentrations are highly variable between individuals. They do not seem to be correlated with the activity or the toxicity of D-penicillamine in patients with rheumatoid arthritis. More than 80% of plasma D-penicillamine is bound to proteins, particularly albumin. The rest is mainly in the free reduced form or as disulphides. Only a small portion of the dose is metabolised in the liver to S-methyl-D-penicillamine. The route of elimination is mainly renal; disulphides represent the main compounds found in the urine. Faecal excretion corresponds mainly to the non-absorbed fraction of the drug.

Chromatography, High Pressure Liquid↗
PubMed1987

[Configuration frequency analysis. XXIII. Types and syndromes of a higher order].

Configural Frequency analysis (CFA) is a method for the detection of significantly high or low frequencies in multivariate contingency tables. As a criterion for the comparisons. CFA uses expected frequencies from log-linear models which reflect assumptions on the association structure of the variables under study. The present paper extends models of CFA such that triplet associations or even higher order associations can be considered. Examples use empirical data from research on depression in children. Results show the existence of higher order types.

Child↗
PubMed1987

Psychological aspects of catecholamine response patterns to pain and mental stress in essential hypertensive patients and controls.

In an experimental study on hypertensive and healthy subjects, the role of anxiety, sex, and disease for the response of plasma epinephrine (E) and norepinephrine (NE) to pain (venipuncture) and mental stress (word alliteration) was investigated. Pain elicited higher E values than mental stress in healthy subjects and higher NE responses in both sexes, but hypertensive subjects did not respond by generally higher catecholamine values than normotensive subjects did. They were, instead, characterized by decreases of NE upon mental stress. Trait anxiety, as measured by questionnaire scores, was associated with higher E values in healthy and hypertensive subjects but mainly after physical pain and not after mental stress. NE responses to pain were significantly lower in anxious than in nonanxious hypertensive subjects, and the opposite held true for normotensive subjects. Thus, high E/low NE response emerged as an indicator of trait anxiety, as well as state anxiety. Correlations between experienced aversiveness and catecholamine levels identified NE as a hormone of successful coping on which hypertensive subjects seem to rely more than normotensive subjects do when trying to counteract their particular threat of physical pain.

Adult↗
PubMed1986

[Familial articular chondrocalcinosis].

Articular chondrocalcinosis is a well-defined radiological entity with or without clinical manifestations. A familial form was described by Sitaj and Zitnan in 1957. Attention has mostly been paid to chondrocalcinosis associated with metabolic diseases and to "sporadic" chondrocalcinosis, usually due to ageing of the joint. Familial chondrocalcinosis, of which more and more cases are reported, is increasingly under study and is used as a model for pathogenic research. It already appears that familial chondrocalcinosis, of dominant autosomal transmission, is a new metabolic disease.

Calcium Pyrophosphate↗
PubMed1986

Association and transfer functions for analysis of drug binding to proteins.

A global association function is proposed that characterizes the apparent overall equilibrium of drug protein binding. It is defined as a function of the total drug concentration and may be directly calculated from each experimental result. The binding transfer function represents the relative rates of change in the bound and free concentrations from the total concentration. Two applications are presented: one is an investigation of the effect of temperature on binding of salicylic acid to proteins in plasma; and the other is a comparison of the phenomenon in two different biological fluids (protein binding of sodium salicylate in plasma and in synovial fluid).

Blood Proteins↗