Proceedings of The National Academy of Sciences, 1998
Postmortem prefrontal cortices (PFC) (Brodmann's areas 10 and 46), temporal cortices (Brodmann's ... more Postmortem prefrontal cortices (PFC) (Brodmann's areas 10 and 46), temporal cortices (Brodmann's area 22), hippocampi, caudate nuclei, and cerebella of schizophrenia patients and their matched nonpsychiatric subjects were compared for reelin (RELN) mRNA and reelin (RELN) protein content. In all of the brain areas studied, RELN and its mRNA were significantly reduced (Ϸ50%) in patients with schizophrenia; this decrease was similar in patients affected by undifferentiated or paranoid schizophrenia. To exclude possible artifacts caused by postmortem mRNA degradation, we measured the mRNAs in the same PFC extracts from ␥-aminobutyric acid (GABA) A receptors ␣ 1 and ␣ 5 and nicotinic acetylcholine receptor ␣ 7 subunits. Whereas the expression of the ␣ 7 nicotinic acetylcholine receptor subunit was normal, that of the ␣ 1 and ␣ 5 receptor subunits of GABA A was increased when schizophrenia was present. RELN mRNA was preferentially expressed in GABAergic interneurons of PFC, temporal cortex, hippocampus, and glutamatergic granule cells of cerebellum. A protein putatively functioning as an intracellular target for the signaltransduction cascade triggered by RELN protein released into the extracellular matrix is termed mouse disabled-1 (DAB1) and is expressed at comparable levels in the neuroplasm of the PFC and hippocampal pyramidal neurons, cerebellar Purkinje neurons of schizophrenia patients, and nonpsychiatric subjects; these three types of neurons do not express RELN protein. In the same samples of temporal cortex, we found a decrease in RELN protein of Ϸ50% but no changes in DAB1 protein expression. We also observed a large (up to 70%) decrease of GAD67 but only a small decrease of GAD65 protein content. These findings are interpreted within a neurodevelopmental͞vulnerability ''twohit'' model for the etiology of schizophrenia.
The relationship between hypothalamic-pituitary-adrenal (HPA) axis function and platelet monoamin... more The relationship between hypothalamic-pituitary-adrenal (HPA) axis function and platelet monoamine oxidase (MAO) activity was examined
Acute Dietary Tryptophan Depletion: Effects on Schizophrenic Positive and Negative Symptoms
Neuropsychobiology, 1997
Because brain serotonin levels depend directly on the amounts of exogenous tryptophan (TRP) avail... more Because brain serotonin levels depend directly on the amounts of exogenous tryptophan (TRP) available for its synthesis, amounts of TRP in the diet may be manipulated to alter the corresponding levels of serotonin. This technique has been used for probing the role of serotonin in mediating various forms of pyschopathology. In this study, 16 patients meeting DSM III-R criteria for schizophrenia (n = 14) or schizoaffective disorder (n = 2) were assessed for the effects of acute dietary TRP depletion under controlled conditions. The hypothesis was that lowering of serotonin would result in a diminution of 'positive' and/or 'negative' symptoms of psychotic disorders. No clinically or statistically significant improvement compared to baseline occurred when TRP depletion was imposed. Indeed, there was a statistically significant deterioration on measures of negative symptoms. The results are discussed in the context of the methodological issues.
Background: Reelin (RELN) is a glycoprotein secreted preferentially by cortical ␥-aminobutyric ac... more Background: Reelin (RELN) is a glycoprotein secreted preferentially by cortical ␥-aminobutyric acidergic (GABAergic) interneurons (layers I and II) that binds to integrin receptors located on dendritic spines of pyramidal neurons or on GABAergic interneurons of layers III through V expressing the disabled-1 gene product (DAB1), a cytosolic adaptor protein that mediates RELN action. To replicate earlier findings that RELN and glutamic acid decarboxylase (GAD) 67 , but not DAB1 expression, are down-regulated in schizophrenic brains, and to verify whether other psychiatric disorders express similar deficits, we analyzed, blind, an entirely new cohort of 60 postmortem brains, including equal numbers of patients matched for schizophrenia, unipolar depression, and bipolar disorder with nonpsychiatric subjects.
A recent report suggests that the down-regulation of reelin and glutamic acid decarboxylase (GAD ... more A recent report suggests that the down-regulation of reelin and glutamic acid decarboxylase (GAD 67 ) mRNAs represents 2 of the more consistent findings thus far described in post-mortem material from schizophrenia (SZ) patients [reviewed in . (2005). Neurochemical markers for schizophrenia, bipolar disorder amd major depression in postmortem brains. Biol Psychiatry 57, 252-260]. To study mechanisms responsible for this down-regulation, we have analyzed the promoter of the human reelin gene. Collectively, our studies suggest that SZ is characterized by a gamma-amino butyric acid (GABA)-ergic neuron pathology presumably mediated by promoter hypermethylation facilitated by the over-expression of the methylating enzyme DNA methyltransferase (Dnmt) 1. Using transient expression assays, promoter deletions and co-transfection assays with various transcription factors, we have shown a clear synergistic action that is a critical component of the mechanism of the trans-activation process. Equally important is the observation that the reelin promoter is more heavily methylated in brain regions in patients diagnosed with SZ as compared to non-psychiatric control subjects [Grayson, D. R., Jia, X., Chen, Y., Sharma, R. P., Mitchell, C. P., & Guidotti, A., et al. (2005). Reelin promoter hypermethylation in schizophrenia. Proc Natl Acad Sci U S A 102, 9341-9346]. The combination of studies in cell lines and in animal models of SZ, coupled with data obtained from post-mortem human material provides compelling evidence that aberrant methylation may be part of a core dysfunction in this psychiatric disease. More interestingly, the hypermethylation concept provides a coherent mechanism that establishes a plausible link between the epigenetic misregulation of multiple genes that are affected in SZ and that collectively contribute to the associated symptomatology.
Reln mRNA and protein levels are reduced by ∼50% in various cortical structures of post-mortem br... more Reln mRNA and protein levels are reduced by ∼50% in various cortical structures of post-mortem brain from patients diagnosed with schizophrenia or bipolar illness with psychosis. To study mechanisms responsible for this down-regulation, we have analyzed the promoter of the human reelin gene. We show that the reelin promoter directs expression of a reporter construct in multiple human cell types: neuroblastoma cells (SHSY5Y), neuronal precursor cells (NT2), differentiated neurons (hNT) and hepatoma cells (HepG2). Deletion constructs confirmed the presence of multiple elements regulating Reln expression, although the promoter activity is promiscuous, i.e. activity did not correlate with expression of the endogenous gene as reflected in terms of reelin mRNA levels. Co-transfection of the -514 bp human reelin promoter with either Sp1 or Tbr1 demonstrated that these transcription factors activate reporter expression by 6-and 8.5-fold, respectively. Within 400 bp of the RNA start site there are 100 potential CpG targets for DNA methylation. Retinoic acid (RA)-induced differentiation of NT2 cells to hNT neurons was accompanied by increased reelin expression and by the appearance of three DNase I hypersensitive sites 5′ to the RNA start site. RA-induced differentiation was also associated with demethylation of the reelin promoter. To test if methylation silenced reelin expression, we methylated the promoter in vitro prior to transfection. In addition, we treated NT2 cells with the methylation inhibitor aza-2′-deoxycytidine and observed a 60-fold increase in reelin mRNA levels. The histone deacetylase inhibitors trichostatin A (TSA) and valproic acid also induced expression of the endogenous reelin promoter, although TSA was considerably more potent. These findings indicate that one determinant responsible for regulating reelin expression is the methylation status of the promoter. Our data also raise the interesting possibility that the down-regulation of reelin expression documented in psychiatric patients might be the consequence of inappropriate promoter hypermethylation.
An implementation and analysis of a concurrent built-in self-test technique
The authors propose a built-in concurrent self-test (BICST) technique for testing combinational l... more The authors propose a built-in concurrent self-test (BICST) technique for testing combinational logic circuits concurrently with their normal operation. They also introduce a concept of sharing the test hardware between identical circuits to reduce the overall area overhead. They implemented this technique in the design of an ALU (arithmetic logic unit) with online test capability in CMOS technology. The additional hardware used for a 12-bit ALU was 19% of the total chip area, and it did not impose any timing overhead on the operation of the ALU. The overhead decreases with an increase in the size of the ALU. The authors define some measures for evaluating the performance of the BICST technique and discuss methods for their computation and include both simulation and analytical results. In addition to detecting permanent faults, the BICST technique can also be used for detecting intermittent and transient faults. The authors propose some methods for detecting intermittent faults and for computing the transient fault coverage.>
IEEE Transactions on Computer-aided Design of Integrated Circuits and Systems, 1988
In this paper, we present a method of testing digital circuits during normal operation. The resou... more In this paper, we present a method of testing digital circuits during normal operation. The resources used to perform on-line testing are those which are inserted to alleviate the off-line testing problem. The off-line testing resources are modified such that during system operation they can also observe the normal inputs and outputs of a combinational circuit under test. The normal inputs to the circuit under test are compared with test vectors in its test set. When a normal input matches a test vector, the circuit output for such an input is typically compressed into a developing signature. When all of the test vectors in the test set have appeared as normal inputs, the signature is read and verified.
Proceedings of The National Academy of Sciences, 1998
Postmortem prefrontal cortices (PFC) (Brodmann's areas 10 and 46), temporal cortices (Brodmann's ... more Postmortem prefrontal cortices (PFC) (Brodmann's areas 10 and 46), temporal cortices (Brodmann's area 22), hippocampi, caudate nuclei, and cerebella of schizophrenia patients and their matched nonpsychiatric subjects were compared for reelin (RELN) mRNA and reelin (RELN) protein content. In all of the brain areas studied, RELN and its mRNA were significantly reduced (Ϸ50%) in patients with schizophrenia; this decrease was similar in patients affected by undifferentiated or paranoid schizophrenia. To exclude possible artifacts caused by postmortem mRNA degradation, we measured the mRNAs in the same PFC extracts from ␥-aminobutyric acid (GABA) A receptors ␣ 1 and ␣ 5 and nicotinic acetylcholine receptor ␣ 7 subunits. Whereas the expression of the ␣ 7 nicotinic acetylcholine receptor subunit was normal, that of the ␣ 1 and ␣ 5 receptor subunits of GABA A was increased when schizophrenia was present. RELN mRNA was preferentially expressed in GABAergic interneurons of PFC, temporal cortex, hippocampus, and glutamatergic granule cells of cerebellum. A protein putatively functioning as an intracellular target for the signaltransduction cascade triggered by RELN protein released into the extracellular matrix is termed mouse disabled-1 (DAB1) and is expressed at comparable levels in the neuroplasm of the PFC and hippocampal pyramidal neurons, cerebellar Purkinje neurons of schizophrenia patients, and nonpsychiatric subjects; these three types of neurons do not express RELN protein. In the same samples of temporal cortex, we found a decrease in RELN protein of Ϸ50% but no changes in DAB1 protein expression. We also observed a large (up to 70%) decrease of GAD67 but only a small decrease of GAD65 protein content. These findings are interpreted within a neurodevelopmental͞vulnerability ''twohit'' model for the etiology of schizophrenia.
The relationship between hypothalamic-pituitary-adrenal (HPA) axis function and platelet monoamin... more The relationship between hypothalamic-pituitary-adrenal (HPA) axis function and platelet monoamine oxidase (MAO) activity was examined
Acute Dietary Tryptophan Depletion: Effects on Schizophrenic Positive and Negative Symptoms
Neuropsychobiology, 1997
Because brain serotonin levels depend directly on the amounts of exogenous tryptophan (TRP) avail... more Because brain serotonin levels depend directly on the amounts of exogenous tryptophan (TRP) available for its synthesis, amounts of TRP in the diet may be manipulated to alter the corresponding levels of serotonin. This technique has been used for probing the role of serotonin in mediating various forms of pyschopathology. In this study, 16 patients meeting DSM III-R criteria for schizophrenia (n = 14) or schizoaffective disorder (n = 2) were assessed for the effects of acute dietary TRP depletion under controlled conditions. The hypothesis was that lowering of serotonin would result in a diminution of 'positive' and/or 'negative' symptoms of psychotic disorders. No clinically or statistically significant improvement compared to baseline occurred when TRP depletion was imposed. Indeed, there was a statistically significant deterioration on measures of negative symptoms. The results are discussed in the context of the methodological issues.
Background: Reelin (RELN) is a glycoprotein secreted preferentially by cortical ␥-aminobutyric ac... more Background: Reelin (RELN) is a glycoprotein secreted preferentially by cortical ␥-aminobutyric acidergic (GABAergic) interneurons (layers I and II) that binds to integrin receptors located on dendritic spines of pyramidal neurons or on GABAergic interneurons of layers III through V expressing the disabled-1 gene product (DAB1), a cytosolic adaptor protein that mediates RELN action. To replicate earlier findings that RELN and glutamic acid decarboxylase (GAD) 67 , but not DAB1 expression, are down-regulated in schizophrenic brains, and to verify whether other psychiatric disorders express similar deficits, we analyzed, blind, an entirely new cohort of 60 postmortem brains, including equal numbers of patients matched for schizophrenia, unipolar depression, and bipolar disorder with nonpsychiatric subjects.
A recent report suggests that the down-regulation of reelin and glutamic acid decarboxylase (GAD ... more A recent report suggests that the down-regulation of reelin and glutamic acid decarboxylase (GAD 67 ) mRNAs represents 2 of the more consistent findings thus far described in post-mortem material from schizophrenia (SZ) patients [reviewed in . (2005). Neurochemical markers for schizophrenia, bipolar disorder amd major depression in postmortem brains. Biol Psychiatry 57, 252-260]. To study mechanisms responsible for this down-regulation, we have analyzed the promoter of the human reelin gene. Collectively, our studies suggest that SZ is characterized by a gamma-amino butyric acid (GABA)-ergic neuron pathology presumably mediated by promoter hypermethylation facilitated by the over-expression of the methylating enzyme DNA methyltransferase (Dnmt) 1. Using transient expression assays, promoter deletions and co-transfection assays with various transcription factors, we have shown a clear synergistic action that is a critical component of the mechanism of the trans-activation process. Equally important is the observation that the reelin promoter is more heavily methylated in brain regions in patients diagnosed with SZ as compared to non-psychiatric control subjects [Grayson, D. R., Jia, X., Chen, Y., Sharma, R. P., Mitchell, C. P., & Guidotti, A., et al. (2005). Reelin promoter hypermethylation in schizophrenia. Proc Natl Acad Sci U S A 102, 9341-9346]. The combination of studies in cell lines and in animal models of SZ, coupled with data obtained from post-mortem human material provides compelling evidence that aberrant methylation may be part of a core dysfunction in this psychiatric disease. More interestingly, the hypermethylation concept provides a coherent mechanism that establishes a plausible link between the epigenetic misregulation of multiple genes that are affected in SZ and that collectively contribute to the associated symptomatology.
Reln mRNA and protein levels are reduced by ∼50% in various cortical structures of post-mortem br... more Reln mRNA and protein levels are reduced by ∼50% in various cortical structures of post-mortem brain from patients diagnosed with schizophrenia or bipolar illness with psychosis. To study mechanisms responsible for this down-regulation, we have analyzed the promoter of the human reelin gene. We show that the reelin promoter directs expression of a reporter construct in multiple human cell types: neuroblastoma cells (SHSY5Y), neuronal precursor cells (NT2), differentiated neurons (hNT) and hepatoma cells (HepG2). Deletion constructs confirmed the presence of multiple elements regulating Reln expression, although the promoter activity is promiscuous, i.e. activity did not correlate with expression of the endogenous gene as reflected in terms of reelin mRNA levels. Co-transfection of the -514 bp human reelin promoter with either Sp1 or Tbr1 demonstrated that these transcription factors activate reporter expression by 6-and 8.5-fold, respectively. Within 400 bp of the RNA start site there are 100 potential CpG targets for DNA methylation. Retinoic acid (RA)-induced differentiation of NT2 cells to hNT neurons was accompanied by increased reelin expression and by the appearance of three DNase I hypersensitive sites 5′ to the RNA start site. RA-induced differentiation was also associated with demethylation of the reelin promoter. To test if methylation silenced reelin expression, we methylated the promoter in vitro prior to transfection. In addition, we treated NT2 cells with the methylation inhibitor aza-2′-deoxycytidine and observed a 60-fold increase in reelin mRNA levels. The histone deacetylase inhibitors trichostatin A (TSA) and valproic acid also induced expression of the endogenous reelin promoter, although TSA was considerably more potent. These findings indicate that one determinant responsible for regulating reelin expression is the methylation status of the promoter. Our data also raise the interesting possibility that the down-regulation of reelin expression documented in psychiatric patients might be the consequence of inappropriate promoter hypermethylation.
An implementation and analysis of a concurrent built-in self-test technique
The authors propose a built-in concurrent self-test (BICST) technique for testing combinational l... more The authors propose a built-in concurrent self-test (BICST) technique for testing combinational logic circuits concurrently with their normal operation. They also introduce a concept of sharing the test hardware between identical circuits to reduce the overall area overhead. They implemented this technique in the design of an ALU (arithmetic logic unit) with online test capability in CMOS technology. The additional hardware used for a 12-bit ALU was 19% of the total chip area, and it did not impose any timing overhead on the operation of the ALU. The overhead decreases with an increase in the size of the ALU. The authors define some measures for evaluating the performance of the BICST technique and discuss methods for their computation and include both simulation and analytical results. In addition to detecting permanent faults, the BICST technique can also be used for detecting intermittent and transient faults. The authors propose some methods for detecting intermittent faults and for computing the transient fault coverage.>
IEEE Transactions on Computer-aided Design of Integrated Circuits and Systems, 1988
In this paper, we present a method of testing digital circuits during normal operation. The resou... more In this paper, we present a method of testing digital circuits during normal operation. The resources used to perform on-line testing are those which are inserted to alleviate the off-line testing problem. The off-line testing resources are modified such that during system operation they can also observe the normal inputs and outputs of a combinational circuit under test. The normal inputs to the circuit under test are compared with test vectors in its test set. When a normal input matches a test vector, the circuit output for such an input is typically compressed into a developing signature. When all of the test vectors in the test set have appeared as normal inputs, the signature is read and verified.
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Papers by Rajiv Sharma