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Biomedical subjects

J Widmer

Publications and source records attributed to J Widmer.

At least 55 records · Page 3Linked to original sources
PubMed1978

[Differences between human and rat blood towards 3,4-dihydroxy-L-phenylalanine and 5-hydroxy-L-tryptophan in vitro. Biochemical and histochemical data (author's transl)].

When incubated with whole human blood at ordinary temperature, 3,4-dihydroxy-L-phenylalanine remains unchanged for at least 30 min. Under the same experimental conditions, 5-hydroxy-L-tryptophan shows a tendency to decrease. When incubated with blood from pentobarbital anaesthetized rats, these aminoacids decrease to about 50% of the added quantity in less than 5 min; thereafter, their level remains stable (3,4-dihydroxy-L-phenyl-alanine) or slowly decreases (5-hydroxy-L-tryptophan).

5-Hydroxytryptophan↗
PubMed1976

Renal excretion of uric acid in the rat: a micropuncture and microperfusion study.

Free-flow micropuncture experiments were done in rats of three strains infused with small amounts of urate [plasma urate (P urate) = 95 +/- 8 muM]. Urate concentrations in tubular fluid were measured by an accurate chemical fluorometric ultramicromethod. In fluid from surface glomeruli, the glomerular fluid-to-plasma urate ratio [GF/P) urate] was 0.99 +/- 0.03 (n=11), i.e., lower than expected for total ultrafiltrability of plasma urate. Along proximal convolutions, net reabsorption of 55% of filtered urate was demonstrated. Small amounts of urate may have been reabsorbed between late proximal and early distal sites. Net transepithelial movements of urate did not occur in distal tubules or collecting ducts. In microperfusion experiments on proximal tubules, both a reabsorptive flow of urate (loss of perfused [2-14C]urate) and a secretory flow (entrance of cold urate into perfusate) of the same order of magnitude were demonstrated. Neither flow was influenced by simultaneous water movements. Microperfusion of Henle's loops indicated a significant but very small net reabsorption.

Aminohippuric Acids↗
PubMedDate not supplied

Does cartoon movie distraction decrease burned children's pain behavior?

The purpose of this study was to evaluate cartoon movie viewing as a practical and low-cost intervention to decrease burned children's pain behavior during dressing changes. Thirteen children, 4 to 12 years of age, with a mean TBSA burn of 7.9% were assessed using a reversal, single-subject experimental design. The experimental condition consisted of the presentation of a cartoon movie as a nonpharmacologic intervention in conjunction with a standardized analgesic medication. In the control condition children's pain was treated with the standardized analgesic medication only. Behavioral distress was measured during the first six dressing changes postburn with the Observational Scale of Behavioral Distress. No significant effect of cartoon movie distraction on observed behavioral distress in patients was found. Interrater reliability of the Observational Scale of Behavioral Distress was good (kappa =.87-.98). Wound debridement was found to be the most painful part of the dressing change. A simple, easily applicable, and low-cost distraction intervention such as presenting cartoon movies does not seem to be sufficiently powerful to measurably reduce burned children's distress during dressing changes. Findings are based on purely observational data. Inclusion of self-report measures in future studies might reveal intervention effects on anxiety and subjective pain perception.

Attention↗
PubMedDate not supplied

Reversible in vitro decrease of L-tyrosine and L-tryptophan influx across the human erythrocyte membrane induced by cytochalasin B, the specific inhibitor of D-glucose transport.

For many years, we have been studying, in psychiatric conditions, the influx of tyrosine (TYR) and tryptophan (TRP), the two amino acid precursors of monoamines, across the membrane of human blood cells. We have also attempted to characterize better the transport mechanisms. In a previous paper, we suggested a close relationship between glucose and the two neuter amino acid transports in vitro. The purpose of the present study is to test the effect of cytochalasin B, the specific and potent inhibitor of glucose transport. Our data show that at high concentrations, the cytochalasin B induces a reversible inhibition of about 70% or more on the temperature-dependent influx of the two amino acids, depending on the medium of incubation. The effect of cytochalasin B was about 200 times less for TYR and TRP transport than for glucose. The cytochalasin E, claimed to be a nonspecific inhibitor, decreased both these transports only when used at very high concentrations, as described for sugar influx in the same structure. In conclusion, we suggest that there is a relationship between the transport of glucose and nucleosides, both carried into the cells by the glycoprotein band 4.5, and the two amino acid precursors of monoamines.

Adult↗
PubMedDate not supplied

[Erythrocyte membrane transport of amino acid precursors of monoamines in schizophrenic patients. Comparison with depressive patients].

The study concerned 72 schizophrenic and 200 depressed patients hospitalised between 1983 and 1990. The erythrocyte membrane transports (EMT) of L-tyrosine and L-tryptophan (at 37 degrees, 0 degrees and 37-0 degrees) of schizophrenics without treatment nor depression were different compared to controls and depressed patients. The schizophrenics under neuroleptic treatment and/or depressed showed same means of EMT values as depressed patients. The slopes of the correlations between EMT of tyrosine or tryptophan at 37 degrees, 0 degrees and 37-0 degrees, as well as that between plasma levels of these amino acids, were parallel. However the slopes of the correlations between EMT of tyrosine and tryptophan were different according to the subgroups of patients: the perturbations of EMT were related to the clinical characteristics. In depressed patients and in schizophrenic patients under neuroleptic treatment and/or depressed, little changes in EMT of tyrosine were related to high changes of EMT of tryptophan.

Antipsychotic Agents↗
PubMedDate not supplied

[Erythrocyte membrane transports of monoamine precursor amino acids in schizophrenia].

We have determined the erythrocyte membrane uptake of the monoamine precursors L-tyrosine (L-TYR) and L-tryptophane (L-TRYP) in 72 patients with schizophrenia: 21 without neuroleptic treatment and not depressed, 15 with neuroleptic treatment and depressed, 33 without neuroleptic treatment, 27 depressed, compared to: 59 control subjects, and 54 depressed patients. We found that the ratio of L-TYR facilitated membrane diffusion to that of L-TRYP is: decreased when the patients are depressed, increased when they are untreated. When untreated patients receive neuroleptics and are depressed, the ratio tends to equal that of depressed patients'. The meaning of these anomalies is analysed, using our up-to-date knowledge of the erythrocytes's role in uptaking and dispatching the human body amino-acids, and of the role of these uptakes in regulating the functional monoamine balance. We postulate that in depressions, Parkinson's disease and schizophrenia, a change of membrane fluidity occurs, being decreased in depressions and Parkinsons's disease, and increased in schizophrenia.

Adult↗
PubMedDate not supplied

[Efficacy of antidepressants selected as a function of erythrocyte membrane transport and plasma levels of L-tyrosine and L-tryptophan].

The present study concerned 69 depressed patients (26 men, 43 women). The antidepressant drug was prescribed in accordance with perturbations of tyrosine and tryptophan membrane transports (MT) across the red cell, measured in vitro after a wash-out period of ten days. After two to four months of treatment, the clinical results were divided into two groups: normal mood (AMDP - Depression Scale less than 6) and no recovery (AMDP - Depression Scale greater than 6). The initial criteria (e.g. MT) was completed by using plasma tyrosine, tryptophan and the product MT by plasma level. Indeed, the success of this treatment was corresponding to precise abnormalities of variable: (i) tyrosine and tryptophan values for imipramine, (ii) tyrosine values, plasma tryptophan and tryptophan product for desipramine, (iii) tryptophan variables and plasma tyrosine for fluvoxamine (and indalpine). The analysis of clinical failures permitted to complete our previous choice of antidepressant drug.

Adult↗
PubMedDate not supplied

[Joint evolution of erythrocyte membrane transport of tyrosine and tryptophan as a function of the clinical course of depression].

The clinical state and the erythrocyte membrane transports of tyrosine and tryptophan were studied longitudinally during one year (minimum period of 3 months) in 44 depressive patients, 21 men and 23 women of 30 to 77 years of age. According to the DSM III, 18 patients had bipolar disorders (8 with short cycles), 14 had recurrent major depressions and 12 dysthymic disorders. Abnormal values for the membrane transports are found in the majority of patients; the pattern of these abnormalities differs among the nosological groups but decreased ratio of the tyrosine to tryptophan is the predominant finding. The membrane transports normalize as the clinical status improves. In bipolar disorders, the changes observed at the time of switching into mania differ among short and long cyclers. Short cyclers who become manic generally present a short period of normal mood and show values of membrane transports higher than when depressed or euthymic and higher than those of normal controls. Long cyclers directly switch into mania, and when manic have the same ratio of tyrosine to tryptophan than when depressed. Based on these biochemical observations, long cyclers resemble patients with recurrent major depression and short cyclers resemble dysthymic disorder patients, a group for which it has been suggested that one fifth become bipolar within years of evolution.

Adult↗
PubMedDate not supplied

[Erythrocyte membrane transport and plasma levels of tyrosine and tryptophan in depression].

L-Tyrosine and L-Tryptophan were studied in 80 depressed patients, hospitalised in Genova and Marseille. After a washout period of ten days, the erythrocyte membrane transports (MT) of L-Tyrosine and L-Tryptophan were measured, as well as their plasma levels; plasma phenylalanine was moreover measured. 33 normal subjects served as control group. In the whole population of patients, the mean of MT's was different compared to controls (MT tyrosine low and MT tryptophan high) and the plasma tyrosine was low. The perturbations of these variables were different according to diagnostic groups (DSM III): MT tyrosine, plasma tyrosine and tryptophan low in bipolar disorders depressed; MT tyrosine low, MT tryptophan high, plasma tryptophan low in major depressions; MT tryptophan high in dysthymic disorders. Phenylalanine was in the normal range compared to controls. The perturbations of MT's involved the part incubated at 37 degrees C for tyrosine, e.g. the facilitated diffusion, and the part incubated at 0 degrees C for tryptophan, e.g. probably the passive and facilitated diffusion. These results were in agreement with the monoaminergic hypothesis of affective disorders and might provide a useful peripheral model.

Adult↗
PubMedDate not supplied

[Erythrocyte membrane transport of L-tyrosine and L-tryptophan in 66 patients with depressive syndromes. Preliminary results].

The transport of Tyrosine and Tryptophan by the membrane of red blood cells has been studied in a group of 66 depressed patients (DSM-III: 27 major depressions, single episode or recurrent; 17 bipolar disorders, depressed; 22 dysthymic disorders). Anomalies were observed: tyrosine transport was decreased in the bipolar disorders and in the major depressions; tryptophan transport was increased in the major depressions and in the dysthymic disorders. These results suggest that membrane transports are disturbed in depressed syndromes, and may be related to dysfunction in the monoaminergic balance.

Adult↗
PubMedDate not supplied

[Choice of antidepressive agents as a function of membrane transport (erythrocytes) of monoamine precursors (L-tyrosine and L-tryptophan)].

In a group of 66 depressed patients, the choice of the antidepressant drug was based upon the result of tyrosine and tryptophan uptake by the membrane of red blood cells. After one month of treatment, 56 subjects were improved, that is 85% of the cases. This result is discussed in comparison with the percentage of improvement described in the literature.

Antidepressive Agents↗