Lars Bjerkenstedt

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BACKGROUND Tyrosine supplementation in humans has been shown to improve cognitive functioning. Several studies have demonstrated a decreased maximal transport capacity of tyrosine (Vmax) across the cell membrane and an increased affinity (Km) of tyrosine to membrane binding sites in schizophrenic patients. A lack of tyrosine for dopamine synthesis with(More)
Eighty-one women with psychosis of schizophrenic and paranoid type were assigned to a double-blind study comparing the clinical effects of melperone (l00 mg × 3) and thiothixene (10 mg × 3). The antipsychotic effect was evaluated by clinical rating according to the CPRS and the NOSIE-30 scales before and after 2 and 4 weeks of drug treatment. A satisfactory(More)
OBJECTIVE To further evaluate the controversial putative association between a Ser9Gly variant in the first exon of the dopamine D3 receptor gene (DRD3) and schizophrenia. METHODS Swedish patients with schizophrenia ( n=156) and control subjects ( n=463) were assessed for the DRD3 Ser9Gly variant. Meta-analyses including previous and the present Swedish(More)
Autism is a developmental, cognitive disorder clinically characterized by impaired social interaction, communication and restricted behaviours. The present study was designed to explore whether an abnormality in transport of tyrosine and/or alanine is present in children with autism. Skin biopsies were obtained from 11 children with autism (9 boys and 2(More)
Clinical and biochemical effects of melperone (100 mg × 3) and thiothixene (10 mg × 3) were studied in women with psychoses of schizophrenic or paranoid type. Psychotic morbidity and side effects were determined by rating scales. Concentrations of the major monoamine metabolites homovanillic acid (HVA), 4-hydroxy-3-methoxyphenyl-ethylene glycol (MOPEG), and(More)
Dopamine receptor gene variation has been hypothesized to influence personality traits characterized by novelty seeking and related traits. We analyzed a dopamine D(3) receptor gene (DRD3) variant in a Swedish population (n = 373) investigated with one or more of several personality questionnaires. No significant relationships were found between DRD3(More)
Human fibroblast cells are an advantageous model to study the transport of amino acids across cell membranes, since one can control the environmental factors. A major problem in all earlier studies is the lack of precise and detailed knowledge regarding the expression and functionality of tyrosine transporters in human fibroblasts. This motivated us to(More)
Several mechanisms have been suggested to account for altered dopaminergic neurotransmission in schizophrenia. The brain is the only organ for which amino-acid transport is limited and competition for transport over the blood-brain barrier (BBB) occurs at physiological plasma concentrations. One line of research suggests that patients with schizophrenia(More)
The catecholaminergic and serotonergic neurotransmitter systems are implicated in the pathophysiology of attention-deficit/hyperactivity disorder (ADHD). The amino acid tyrosine is the precursor for synthesis of the catecholamines dopamine and norepinephrine, while tryptophan is the precursor of serotonin. A disturbed transport of tyrosine, as well as other(More)
OBJECTIVE Disturbances in catecholamine transmission have been implicated in schizophrenia. Dopamine beta-hydroxylase catalyses the conversion of dopamine to norepinephrine in noradrenergic cells. We attempted to investigate a putative functional promoter polymorphism in the dopamine beta-hydroxylase gene (DBH) for association with schizophrenia. METHODS(More)