Homocysteinemia and schizophrenia as a case of methylation deficiency

Summary MK-801, a non-competitive antagonist of NMDA receptors, is known to exhibit a beneficial action in many animal models of Parkinson's disease. The aim of this study was to examine the influence of MK-801 on the reserpine-induced muscle rigidity. The rigidity was estimated by a direct mechanomyographic method. This method consists in successive bending and traightening of a rat's hind foot in the ankle joint and measuring the resistance of the foot to passive movements. Reserpine in doses of 5–10 mg/kg ip, given alone or in combination with -methyl-p-tyrosine (MT, 250 mg/kg ip), induced rigidity. The strongest muscle rigidity was induced by 10 mg/kg of reserpine 1 hour after administration. MK-801 (0.32–1.28 mg/kg sc) injected 70 min after reserpine (10 mg/kg ip) decreased the rigidity induced by the latter compound. Similarly, MK-801 (1.28 mg/kg sc), administered 27 h 40 after joint treatment with reserpine (10 mg/kg ip) and MT (250 mg/kg ip), strongly inhibited the reserpine-induced muscle rigidity. The obtained results show that the glutamatergic hyperactivity plays a significant role in the reserpine-induced rigidity. As the reserpine-induced motor disturbances are commonly accepted to be an animal model of parkinsonian symptoms, it may be assumed that the NMDA receptor blocking component may contribute substantially to the therapeutic action of antiparkinsonian drugs.     

Studies on duration of a late recovery period after chronic abuse of ethanol. A cross-sectional study of biochemical and psychiatric indicators

A cross-sectional study on patients with different abstinence time was performed to describe long-time biochemical and psychiatric changes due to withdrawal from heavy alcohol abuse. Physical, neurological, psychiatric and biochemical parameters were measured in 70 patients with a withdrawal period ranging from 2-90 days. The various parameters changed over time in different manners. Fatigability, reduced sleep, reduced sexual interest, apparent sadness, hostility and global ratings of abstinence improved significantly with the duration of the recovery period. Symptoms related to brain hyperexcitability such as fatigability, inner tension, insomnia and pains persisted for approximately 5 weeks. Of the biochemical parameters, the transaminases were normal in patients with more than 10 days of abstinence, while the levels of gamma-glutamyltransferase and HDL-cholesterol remained high for longer periods. The essential fatty acid status, measured by the fatty acid composition of serum lecithin, appeared to be normal only in patients with long recovery time. MAO in platelets was significantly lower than in the controls. The highest values were seen in the early recovery phase, which may indicate a temporary increase. Since polyunsaturated fatty acids are important constituents of synaptic membranes and since platelet MAO may reflect brain MAO, we consider these co-existing findings important in the interpretation of the psychiatric symptoms. The study demonstrated the existence of a subacute withdrawal syndrome lasting for 4-6 weeks.     

Experimental modelling of drug membrane permeability by capillary electrophoresis using liposomes, micelles and microemulsions

Capillary electrophoresis (CE) was evaluated as an in-vitro format for experimental modelling of membrane permeability using only nanogram quantities of drug compounds. The rationale for the CE technique emanates from emulation of a lipid-like pseudo-stationary phase that governs separations mainly as a result of differences in molecular size, lipophilicity, hydrogen bonding and charge, all of which also have a strong influence on in-vivo drug absorption. By means of micellar, microemulsion and liposome electrolytes, the migration behaviour was studied at 37 degrees C for 22 model drug compounds. The generated CE retention factor data were then compared with membrane permeability reference data. Both simple log D and more common Caco-2 cell parameters were evaluated. In addition, permeation through intestinal segments of rat ileum and rat colon was included. An improved correlation was obtained in the order: micellar < microemulsion < liposome systems. Although the correlation for the best liposome CE system was only R(2)=0.77, the evaluation results for all emphasized the strength and flexibility of CE for assessing specific drug-membrane interaction through tailor-made lipophilic media.     

Biochemical changes in Dementia disorders of Alzheimer type (AD/SDAT)

In postmortem investigations of patients with dementia of Alzheimer type (AD/SDAT) (n = 14) the brain weight was significantly reduced when compared to controls (n = 16). In four AD/SDAT-brain parts investigated the concentrations of 5-hydroxy-tryptamine and noradrenaline were significantly reduced while 3-methoxy-4-hydroxyphenylglycol was significantly increased. In the caudate nucleus of the AD/SDAT-brains the concentrations of dopamine and homovanillic acid were significantly reduced. The activity of monoamine oxidase B was increased suggesting a proliferation of extra neuronal tissue in the AD/SDAT-brains. The activity of choline acetyl transferase was reduced in the four brain parts investigated, showing a general reduction in the acetylcholine system in the AD/SDAT-brains. The ganglioside concentration was significantly reduced suggesting a reduced density of nerve endings in the demented brains. The AD/SDAT-group was according to rating scales severely demented. Patients with an early onset of the dementia disease were more severely intellectually reduced and had more pronounced biochemical disturbances than those with a late onset of the dementia.     

Statistical molecular design, parallel synthesis, and biological evaluation of a library of thrombin inhibitors

A library of thrombin inhibitors has been designed using statistical molecular design. An aromatic scaffold was used, with three varied positions corresponding to three pockets at the active site of thrombin (the S-, P-, and D-pockets). The selection was performed in the building block space, and previously acquired data were included in the design procedure. The design resulted in six, four, and six building blocks for the first (S), second (P), and third (D) pockets, respectively. A second round of selection applied to the combined selected building blocks resulted in a subset of 18 compounds. The selected library was synthesized in parallel and biologically evaluated. The compounds were analyzed with respect to their inhibition (pIC(50)) of thrombin; membrane permeability, estimated by migration behavior in micellar media (CE log k') and pK(a); and specificity with respect to inhibition (K(i)) of trypsin. Multivariate QSAR studies of the responses yielded valuable results and information that could only be found using statistical molecular design in combination with multivariate analysis.     

Is Alzheimer's a homogeneous disease, Are plaques critical and Does the blood brain barrier really contribute?

Several problems exist with the speculative hypothesis presented. The relationship between neuritic plaques and clinical symptoms is not well established and is further complicated by the likely existence of multiple subforms of Alzheimer's disease. Moreover, direct support for changes in the blood brain barrier with Alzheimer's disease is lacking, and the available circumstantial evidence argues against it having an important role in the pathogenesis of the disease.     

Concentration gradients for monoamine metabolites in lumbar cerebrospinal fluid

Summary Concentration gradients in lumbar cerebrospinal fluid (CSF) for the monoamine metabolites homovanillic acid (HVA), 5-hydroxy-indoleacetic acid (5-HIAA) and 4-hydroxy-3-methoxyphenylglycol (HMPG) were studied in 9 healthy controls and 47 neuropsychiatric patients without diseases causing disturbed CSF circulation. In a serial sampling of the first 24 ml of CSF, steep concentration gradients between the first (0–4 th ml) and last (21th–24th ml) portions of CSF were found for HVA (99±59% increase; p<0.001) and 5-HIAA (88±54% increase; p<0.001), while the concentration gradient was slight for HMPG (11±7% increase; p<0.001). The existence of marked concentration gradients for the monoamine metabolites HVA and 5-HIAA gives further evidence for an active transport system for these metabolites and indicates that the lumbar CSF-HVA and 5-HIAA levels reflect the dopamine and serotonin metabolism in the brain. Moreover, the existence of pronounced concentration gradients for HVA and 5-HIAA levels reflect the dopamine and serotonin metabolism in the brain. Moreover, the existence of pronounced concentration gradients for HVA and 5-HIAA stresses the importance of making analyses on a standardized volume of CSF.     

Differences in cerebrospinal fluid gangliosides between "probable Alzheimer's disease" and normal aging.

The four major brain gangliosides, GM1, GD1a, GD1b, and GT1b, were determined in cerebrospinal fluid (CSF) of 43 patients with "probable Alzheimer's disease (AD)" and 40 healthy controls without psychiatric or neurological disorders. The total concentration of the four gangliosides did not differ significantly between "probable AD" group (116 +/- 58 nmol/L) and controls (92 +/- 31 nmol/L), but the proportion between the gangliosides was changed. In the "probable AD" group compared with the age-matched control group, there was an increase in both the GM1 (22.6 +/- 9.3% vs 12.6 +/- 4.1%; p < 0.0001) and GD1a (32.1 +/- 9.8% vs 23.3 +/- 5.7%; p < 0.0005) proportion, and a decrease in the GD1b (20.0 +/- 6.6% vs 23.8 +/- 6.0%; p < 0.05) and GT1b (25.3 +/- 7.9 vs 40.3 +/- 9.3%; p < 0.0001) proportion. The proportion of GM1 showed a positive correlation with age in the control group (r = 0.45; p < 0.01), but a negative correlation with age in the "probable AD" group (r = -0.37; p < 0.05). Thus, although the increase in proportion GM1 in the "probable AD" group was preferentially found in younger "probable AD" patients, it was not caused by age differences. While the pathogenetic mechanism for these changes in CSF-gangliosides in "probable AD" remains to be established, it may reflect the degeneration of nerve cells and synapses.