Cortical GABA markers identify a molecular subtype of psychotic and bipolar disorders.

BACKGROUND: Deficits in gamma aminobutyric acid (GABA) neuron-related markers, including the GABA-synthesizing enzyme GAD67, the calcium-binding protein parvalbumin, the neuropeptide somatostatin, and the transcription factor Lhx6, are most pronounced in a subset of schizophrenia subjects identified as having a 'low GABA marker' (LGM) molecular phenotype. Furthermore, schizophrenia shares degrees of genetic liability, clinical features and cortical circuitry abnormalities with schizoaffective disorder and bipolar disorder. Therefore, we determined the extent to which a similar LGM molecular phenotype may also exist in subjects with these disorders. METHOD: Transcript levels for GAD67, parvalbumin, somatostatin, and Lhx6 were quantified using quantitative PCR in prefrontal cortex area 9 of 184 subjects with a diagnosis of schizophrenia (n = 39), schizoaffective disorder (n = 23) or bipolar disorder (n = 35), or with a confirmed absence of any psychiatric diagnoses (n = 87). A blinded clustering approach was employed to determine the presence of a LGM molecular phenotype across all subjects. RESULTS: Approximately 49% of the subjects with schizophrenia, 48% of the subjects with schizoaffective disorder, and 29% of the subjects with bipolar disorder, but only 5% of unaffected subjects, clustered in the cortical LGM molecular phenotype. CONCLUSIONS: These findings support the characterization of psychotic and bipolar disorders by cortical molecular phenotype which may help elucidate more pathophysiologically informed and personalized medications.

[ZSE-DUO - dual guidance structure at the centre for rare diseases]. / ZSE-DUO ­ duale Lotsenstruktur im Zentrum für Seltene Erkrankungen.

BACKGROUND: Patients with an unclear diagnosis and suspected rare disease pose special challenges to physicians, among others. AIM OF THE STUDY (RESEARCH QUESTION): The ZSE-DUO project aims to establish whether patient care under the joint supervision of a somatic expert and a mental health expert can improve diagnostic efficacy and precision, as well as shorten the time to diagnosis. MATERIAL AND METHODS: ZSE-DUO has successfully recruited more than 1000 patients at eleven national centres for rare diseases in a control and an intervention group. The findings are being analysed by three evaluating institutions. RESULTS AND DISCUSSION: The study is currently in its final phase. The results will be published in further papers.

Potential double-flipping mechanism by E. coli MutY.

To understand the structural basis of the recognition and removal of specific mismatched bases in double-stranded DNAs by the DNA repair glycosylase MutY, a series of structural and functional analyses have been conducted. MutY is a 39-kDa enzyme from Escherichia coli, which to date has been refractory to structural determination in its native, intact conformation. However, following limited proteolytic digestion, it was revealed that the MutY protein is composed of two modules, a 26-kDa domain that retains essential catalytic function (designated p26MutY) and a 13-kDa domain that is implicated in substrate specificity and catalytic efficiency. Several structures of the 26-kDa domain have been solved by X-ray crystallographic methods to a resolution of up to 1.2 A. The structure of a catalytically incompetent mutant of p26MutY complexed with an adenine in the substrate-binding pocket allowed us to propose a catalytic mechanism for MutY. Since reporting the structure of p26MutY, significant progress has been made in solving the solution structure of the noncatalytic C-terminal 13-kDa domain of MutY by NMR spectroscopy. The topology and secondary structure of this domain are very similar to that of MutT, a pyrophosphohydrolase. Molecular modeling techniques employed to integrate the two domains of MutY with DNA suggest that MutY can wrap around the DNA and initiate catalysis by potentially flipping adenine and 8-oxoguanine out of the DNA helix.

Structures of Thymosin Proteins.

The thymosin proteins are all short, highly charged, intrinsically unstructured proteins under natural conditions. However, structure can be induced in many of the thymosin proteins by providing charge neutralization at low pH or by the addition of Zn(2+) ions, organic reagents such as trifluoroethanol, hexafluoropropanol, or n-dodecyltrimethylammonium bromide, or interactions with their natural binding partner proteins. The differing structures of thymosin alpha and thymosin beta proteins have been studied by circular dichroism, nuclear magnetic resonance, and crystallographic methods in order to better understand the role of these proteins. In this structural biology review the structures of prothymosin, parathymosin, thymosin alpha-1, and several beta thymosin proteins, in both native states and under secondary structure-inducing conditions are discussed.

Decreased glutamic acid decarboxylase67 messenger RNA expression in a subset of prefrontal cortical gamma-aminobutyric acid neurons in subjects with schizophrenia.

BACKGROUND: Markers of gamma-aminobutyric acid (GABA) neurotransmission seem to be altered in the prefrontal cortex (PFC) of subjects with schizophrenia. We sought to determine whether the expression of the messenger RNA (mRNA) for the synthesizing enzyme of GABA, glutamic acid decarboxylase67 (GAD67), is decreased in the PFC of subjects with schizophrenia, whether this change is present in all or only some GABA neurons, and whether long-term treatment with haloperidol decanoate contributes to altered GAD67 mRNA expression. METHODS: Tissue sections from 10 pairs of subjects with schizophrenia and control subjects and 4 pairs of haloperidol-treated and control monkeys were processed for in situ hybridization histochemical analysis with sulfur-35-labeled oligonucleotide probes for GAD67 mRNA and exposed to nuclear emulsion. Within each layer of PFC area 9, neurons expressing a detectable level of GAD67 mRNA were quantified for cell density and the relative level of mRNA expression per cell (grain density per neuron). RESULTS: In subjects with schizophrenia, the density of labeled neurons was significantly (P<.05) decreased by 25% to 35% in cortical layers 3 to 5. In contrast, the mean grain density per labeled neuron did not differ across subject groups. Similar analyses in monkeys revealed no effect of long-term haloperidol treatment on either the density of the labeled neurons or the grain density per labeled neuron. CONCLUSIONS: These findings indicate that in subjects with schizophrenia, GAD67 mRNA expression is relatively unaltered in most PFC GABA neurons but is reduced below a detectable level in a subset of GABA neurons. Altered GABA neurotransmission in this subset may contribute to PFC dysfunction in subjects with schizophrenia.

Altered GABA neurotransmission and prefrontal cortical dysfunction in schizophrenia.

Dysfunction of the dorsolateral prefrontal cortex appears to be a central feature of the pathophysiology of schizophrenia, and this dysfunction may be related to alterations in gamma aminobutyric acid (GABA) neurotransmission. Determining the causes and consequences of altered GABA neurotransmission in schizophrenia, and the relationship of these changes to other abnormalities in prefrontal cortical circuitry, requires an understanding of which of the multiple subpopulations of cortical GABA neurons are affected. The chandelier class of GABA neurons, especially those located in the middle layers of the prefrontal cortex (PFC), have been hypothesized to be preferentially involved in schizophrenia because they 1) receive direct synaptic input from dopamine axons, 2) exert powerful inhibitory control over the excitatory output of layer 3 pyramidal neurons, and 3) undergo substantial developmental changes during late adolescence, the typical age of onset of schizophrenia. Consistent with this hypothesis, the axon terminals of chandelier neurons, as revealed by immunoreactivity for the GABA membrane transporter, are reduced substantially in the middle layers of the PFC in schizophrenic subjects. This alteration appears to be selective for the chandelier class of GABA neurons and for the disease process of schizophrenia. These findings provide insight into the pathophysiologic mechanisms underlying prefrontal cortical dysfunction in schizophrenia, and they reveal new targets for therapeutic intervention in this illness.

GABA transporter-1 mRNA in the prefrontal cortex in schizophrenia: decreased expression in a subset of neurons.

OBJECTIVE: Within the prefrontal cortex of schizophrenic subjects, alterations in markers of gamma-aminobutyric acid (GABA) neurotransmission, including decreased immunoreactivity for the GABA membrane transporter GAT-1, may be most prominent in a subset of inhibitory neurons. In the present study, the authors sought to determine whether the alterations in GAT-1 protein could be attributed to a reduction in GAT-1 mRNA expression. METHOD: Tissue sections containing prefrontal cortex area 9 from 10 matched pairs of schizophrenic and comparison subjects were processed for in situ hybridization histochemistry with (35)S-oligonucleotide probes for GAT-1 mRNA. RESULTS: In the schizophrenic subjects, the relative density of labeled neurons was 21%-33% lower in layers 1-5 of the prefrontal cortex but was unchanged in layer 6. In contrast, cellular levels of GAT-1 mRNA expression, as reflected in grain density per labeled neuron, did not differ by more than 11% between subject groups in any layer. These findings indicate that GAT-1 mRNA expression is relatively unaltered in the majority of prefrontal cortex GABA neurons in schizophrenic subjects but is reduced below a detectable level in a subset of GABA neurons. Furthermore, the magnitude and laminar pattern of these results were strikingly similar to those found in a previous study of mRNA expression for the synthesizing enzyme of GABA, glutamic acid decarboxylase(67), in the same subjects. CONCLUSIONS: Both GABA synthesis and reuptake appear to be altered at the level of gene expression in a subset of GABA neurons, and the resulting changes in GABA neurotransmission may contribute to prefrontal cortex dysfunction in schizophrenia.

Radiation induction of drug resistance in RIF-1: correlation of tumor and cell culture results.

The RIF-1 tumor line contains cells that are resistant to various anti-neoplastic drugs, including 5-fluorouracil (5FU), methotrexate (MTX), adriamycin (ADR), and etoposide (VP16). The frequency of these drug-resistant cells is increased after irradiation. The frequency of drug-resistant cells and the magnitude of radiation-induced drug resistance are different in cell culture than in tumors. The dose-response and expression time relationships for radiation induction of drug resistance observed in RIF-1 tumors are unusual. We hypothesize that at high radiation doses in vivo, we are selecting for cells that are both drug resistant and radiation resistant due to microenvironmental factors, whereas at low radiation doses in vivo and all radiation doses in vitro, we are observing true mutants. These studies indicate that there can be significant differences in drug-resistance frequencies between tumors and their cell lines of origin, and that radiation induction of drug resistance depends significantly on whether the induction is done in tumors or in cell culture. These results imply that theories about the induction of drug resistance that are based on cell culture studies may be inapplicable to the induction of drug resistance in tumors.

Depression in the context of human immunodeficiency virus infection: implications for treatment.

A chart review of 90 male outpatients was conducted to document the type of depressive symptomatology associated with HIV infection and to review the nature of antidepressant treatment provided in two university-affiliated outpatient settings. Forty-five individuals who tested positive for HIV infection and who were treated with antidepressant medications were compared with a like number of individuals who had no known risk factors as determined by chart review for HIV infection. Although depressive symptoms were generally similar among the two groups, HIV-positive individuals reported greater decreases in sleep and appetite than the HIV-negative comparison group. Overall, imipramine and fluoxetine earned the most favorable efficacy ratings while producing minimal side effect ratings in both HIV-positive and HIV-negative patients. Among the HIV-positive patients, the asymptomatic group had a better response to treatment with antidepressant medications than either the ARC or AIDS patient groups.

Chronic hypoxia induced ultrastructural changes in the rat adrenal zona glomerulosa.

The adrenal cortex plays an important role in adaptation to various forms of stress, including hypoxia. While physiological changes in the aldosterone metabolism during hypoxia have been extensively described, few studies have focused on the morphological changes in the adrenal glands under chronic hypoxia. We studied the ultrastructure of the zona glomerulosa of 6-month-old Wistar rats exposed to chronic normobaric hypoxia. Animals were divided into two groups: control (n=12) and hypoxic (n=12). In this latter group, the animals were kept at 7% O2 concentration after a gradual adaptation (21, 15, 12, 10, 8, 7 vol% O2). The duration of the study was 112 days. In comparison with normoxic rats, body weight and adrenal gland weight of hypoxic animals was significantly reduced by 18.5% (p=0.006) and 14.7% (p=0.001) respectively. The thickness of the zona glomerulosa decreased due to atrophy of cells. The main ultrastructural changes observed were: 1) a decrease in, or complete elimination of, lipid droplet content; 2) a marked increase in lysosome number; and 3) the presence of giant mitochondria. Our findings show that rats fail to adapt to severe chronic hypoxia. The ultrastructural changes in the zona glomerulosa found in the present study could reflect changes in the aldosterone pathway.

Increased density of microtubule associated protein 2-immunoreactive neurons in the prefrontal white matter of schizophrenic subjects.

Recent studies have suggested that schizophrenia may be related to prenatal disturbances in the cortical subplate, a transient but essential structure in the formation of cerebral cortical circuitry. Although most subplate neurons die during later development, some remain as the interstitial neurons of the adult white matter. In this study we used a monoclonal antibody against the cytoskeletal protein, microtubule associated protein-2 (MAP2), to quantify the density and distribution of labeled neurons in postmortem brain specimens containing the prefrontal white matter from five schizophrenic cases and matched controls. In both schizophrenics and matched controls, the density of white matter neurons decreased with increasing white matter depth. However, the mean density of MAP2-immunoreactive neurons was greater in the superficial white matter of the schizophrenic subjects compared to the matched controls. In contrast, no difference in the density of labeled neurons was seen in the deeper white matter. These findings are consistent with an abnormality in the development of the cortical subplate in at least some cases of schizophrenia.

Toxoplasma infection and cell free extract of the parasites are able to reverse multidrug resistance of mouse lymphoma and human gastric cancer cells in vitro.

A large number of compounds are known to reduce the ATP-dependent efflux pump activity of multidrug resistant (mdr) tumor cells. Here we report that an infection of cancer cells with T. gondii reduced the multidrug resistance of the tumour cells against cytostatic drugs. Two mouse lymphoma cell lines (Mdr L 5718 and Par 5718) were infected with Toxoplasma gondii in vitro and the reduction of efflux pump activity of the cells was measured. The drug accumulation (Rhodamin-123) was increased in the infected mdr cell lines compared with non- infected mdr-cells, and no effect was shown after infection of the parental cell line. The same effect was also achieved by incubation of Mdr-tumor cells with cell lysate of Toxoplasma gondii. Mdr-1-gene expression was reduced in the infected cell lines 48 hours after infection. Co-cultivation of Toxoplasma gondii with mdr cell lines separated by a microfilter from tumor cells was performed, but this cocultivation did not change the mdr efflux activity. The effect of Toxoplasma gondii infection on the efflux pump activity and mdr-1 gene expression was also examined in the human gastric cancer cells. A sensitization of resistant gastric cancer cells was also achieved by parasite infection. This phenomenon is an evidence that a reduction of resistance in tumor cells can be achieved by a natural parasite infection. It is as yet unclear whether an active infection or another substance of T. gondii is responsible for this phenomenon.

Glycogen storage disease type IB.

During the past decade, several cases of glycogen storage disease (GSD) type IB have been reported. However, there has not been a detailed morphologic description of this entity to date. We studied GSD type IB in two siblings, of which one case was enzymatically proved. We compared light and electron microscopic observations with those of GSD type I.

Population oscillations in a discrete model of neural networks of the brain.

A discrete model of biological neural networks is used to find out how synchronized firing of neurons emerges in a randomly connected neural population. The objective is to understand the mechanisms underlying brain waves and to find and characterize conditions which support spontaneous switching from disordered to rhythmic population activity as in case of an epileptic seizure. The model is kept as simple as possible to achieve on one hand a fast performance of computer simulations of networks with up to 10,000 neurons and to keep on the other hand an overview of parameter dependences. Dynamics of the model can be classified into different regimes: random fluctuations, rhythmic oscillations and silence. When the ratio of the inhibitory/excitatory connectivity is raised the system crosses from the fluctuating regime through the rhythmic oscillating region to the silence regime. Close to the boundary between the fluctuating and the oscillating regimes the network shows spontaneous bursting of high amplitude rhythmic oscillations, which is characteristic of epileptiform behavior. The simulation results are in agreement with recent theories saying that focal epilepsy after injury of the brain could result from axonal sprouting of GABAergic neurons in the injured region.

Prenatal ontogeny as a susceptibility period for cortical GABA neuron disturbances in schizophrenia.

Cognitive deficits in schizophrenia have been linked to disturbances in GABA neurons in the prefrontal cortex (PFC). Furthermore, cognitive deficits in schizophrenia appear well before the onset of psychosis and have been reported to be present during early childhood and even during the first year of life. Taken together, these data raise the following question: Does the disease process that produces abnormalities in prefrontal GABA neurons in schizophrenia begin prenatally and disrupt the ontogeny of cortical GABA neurons? Here, we address this question through a consideration of evidence that genetic and/or environmental insults that occur during gestation initiate a pathogenetic process that alters cortical GABA neuron ontogeny and produces the pattern of GABA neuron abnormalities, and consequently cognitive difficulties, seen in schizophrenia. First, we review available evidence from postmortem human brain tissue studies characterizing alterations in certain subpopulations of prefrontal GABA neuron that provide clues to a prenatal origin in schizophrenia. Second, we review recent discoveries of transcription factors, cytokine receptors, and other developmental regulators that govern the birth, migration, specification, maturation, and survival of different subpopulations of prefrontal GABA neurons. Third, we discuss recent studies demonstrating altered expression of these ontogenetic factors in the PFC in schizophrenia. Fourth, we discuss the potential role of disturbances in the maternal-fetal environment such as maternal immune activation in the development of GABA neuron dysfunction. Finally, we propose critical questions that need to be answered in future research to further investigate the role of altered GABA neuron ontogeny in the pathogenesis of schizophrenia.