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H M Gurling

Publications and source records attributed to H M Gurling.

At least 19 recordsLinked to original sources
PubMed2001

Genetic association studies of schizophrenia using the 8p21-22 genes: prepronociceptin (PNOC), neuronal nicotinic cholinergic receptor alpha polypeptide 2 (CHRNA2) and arylamine N-acetyltransferase 1 (NAT1).

Schizophrenia is a common, genetically heterogeneous disorder with a lifetime prevalence of approximately 1% in the general population. Linkage studies of affected families have now strongly implicated a susceptibility locus on chromosome 8p21-22. Tests of allelic association with markers on 8p21-22 should be able to localise any quantitative trait nucleotides (QTN's) or susceptibility mutations to within a few hundred kilobases. Three brain expressed candidate susceptibility genes, prepronociceptin (PNOC), neuronal cholinergic receptor, nicotinic, alpha polypeptide 2 (CHRNA2) and arylamine N-acetyltransferase 1 (NAT1) have been mapped to chromosome 8p21-22. A case-control, allelic association study was performed using a novel highly polymorphic dinucleotide repeat, D8S2611 near the PNOC gene, two previously characterised dinucleotide repeats, D8S131 and D8S131P at the CHRNA2 locus and an RFLP at the 3'UTR of the arylamine N-acetyltransferase 1 (NAT1) gene. No differences were found in allele frequencies between the patient and control groups. DNA variations or mutations at or near the three genes under study are unlikely to increase susceptibility to schizophrenia in our population sample.

3' Untranslated Regions↗
PubMed2001

Enhanced cationic liposome-mediated transfection using the DNA-binding peptide mu (mu) from the adenovirus core.

Promising advances in nonviral gene transfer have been made as a result of the production of cationic liposomes formulated with synthetic cationic lipids (cytofectins) that are able to transfect cells. However few cationic liposome systems have been examined for their ability to transfect CNS cells. Building upon our earlier use of cationic liposomes formulated from 3beta-[N-(N',N'-dimethylaminoethane)carbamoyl] cholesterol (DC-Chol) and dioleoyl-L-alpha-phosphatidyl-ethanolamine (DOPE), we describe studies using two cationic viral peptides, mu (mu) and Vp1, as potential enhancers for cationic liposome-mediated transfection. Mu is derived from the condensed core of the adenovirus and was selected to be a powerful nucleic acid charge neutralising and condensing agent. Vp1 derives from the polyomavirus and harbours a classical nuclear localisation signal (NLS). Vp1 proved disappointing but lipopolyplex mixtures formulated from pCMVbeta plasmid, mu peptide and DC-Chol/DOPE cationic liposomes were able to transfect an undifferentiated neuronal ND7 cell line with beta-galactosidase reporter gene five-fold more effectively than lipoplex mixtures prepared from pCMVbeta plasmid and DC-Chol/DOPE cationic liposomes. Mu was found to give an identical enhancement to cationic liposome-mediated transfection of ND7 cells as poly-L-lysine (pLL) or protamine sulfate (PA). The enhancing effects of mu were found to be even greater (six- to 10-fold) when differentiated ND7 cells were transfected with mu-containing lipopolyplex mixtures. Differentiated ND7 cells represent a simple ex vivo-like post-mitotic CNS cell system. Successful transfection of these cells bodes well for transfection of primary neurons and CNS cells in vivo. These findings have implications for experimental and therapeutic uses of cationic liposome-mediated delivery of nucleic acids to CNS cells.

Animals↗
PubMed2001

Genomewide genetic linkage analysis confirms the presence of susceptibility loci for schizophrenia, on chromosomes 1q32.2, 5q33.2, and 8p21-22 and provides support for linkage to schizophrenia, on chromosomes 11q23.3-24 and 20q12.1-11.23.

We have performed genetic linkage analysis in 13 large multiply affected families, to test the hypothesis that there is extensive heterogeneity of linkage for genetic subtypes of schizophrenia. Our strategy consisted of selecting 13 kindreds containing multiple affected cases in three or more generations, an absence of bipolar affective disorder, and a single progenitor source of schizophrenia with unilineal transmission into the branch of the kindred sampled. DNA samples from these families were genotyped with 365 microsatellite markers spaced at approximately 10-cM intervals across the whole genome. We observed LOD scores >3.0 at five distinct loci, either in the sample as a whole or within single families, strongly suggesting etiological heterogeneity. Heterogeneity LOD scores >3.0 in the sample as a whole were found at 1q33.2 (LOD score 3.2; P=.0003), 5q33.2 (LOD score 3.6; P=.0001), 8p22.1-22 (LOD score 3.6; P=.0001), and 11q21 (LOD score 3.1; P=.0004). LOD scores >3.0 within single pedigrees were found at 4q13-31 (LOD score 3.2; P=.0003) and at 11q23.3-24 (LOD score 3.2; P=.0003). A LOD score of 2.9 was also found at 20q12.1-11.23 within in a single family. The fact that other studies have also detected LOD scores >3.0 at 1q33.2, 5q33.2, 8p21-22 and 11q21 suggests that these regions do indeed harbor schizophrenia-susceptibility loci. We believe that the weight of evidence for linkage to the chromosome 1q22, 5q33.2, and 8p21-22 loci is now sufficient to justify intensive investigation of these regions by methods based on linkage disequilibrium. Such studies will soon allow the identification of mutations having a direct effect on susceptibility to schizophrenia.

Chromosome Aberrations↗
PubMed2001

Mild learning difficulties and offending behaviour--is there a link with monoamine oxidase A deficiency?

We have attempted to replicate the findings of Brunner et al., who described a large Dutch kindred where several males were of borderline intelligence and showed characteristically aggressive and sometimes dangerous or extremely antisocial behaviour. The genetic defect for this syndrome was assigned to the p11-p21 region of the X chromosome following linkage analysis in a single kindred. Subsequent sequencing of a candidate gene, monoamine oxidase A (MAO-A), at the position of maximum linkage revealed a causative mutation in the coding region of the MAO-A gene in position 936. In addition to identifying both the phenotype and the associated mutation found by Brunner et al., we also wished to test the hypothesis that mutations elsewhere in the MAO-A gene could cause the low intelligence quotient/personality disorder phenotype associated with low urinary catecholamine degradation products. Fifty-four male subjects similar in clinical characteristics to the affected males in the Dutch kindred were identified within secure mental health facilities in England and Wales. All were assessed using the antisocial personality disorder section of the SCID-II interview instrument, and information about their offending behaviour and family history was obtained from the medical notes. A blood and early-morning urine sample was obtained from each patient. Analysis of urinary excretion patterns of biogenic amines and their metabolites, represented as ratios of normetanefrine to vanillylmandelic acid, revealed two possible cases of MAO-A deficiency, which were found to be negative after resampling.

Antisocial Personality Disorder↗
PubMed2000

Identification of a novel gene on chromosome 7q31 that is interrupted by a translocation breakpoint in an autistic individual.

The results of genetic linkage studies for autism have suggested that a susceptibility locus for the disease is located on the long arm of chromosome 7 (7q). An autistic individual carrying a translocation, t(7;13)(q31.3;q21), with the chromosome 7 breakpoint located in the region of 7q implicated by genetic studies was identified. A novel gene known as "RAY1" (or "FAM4A1") was found to be directly interrupted by the translocation breakpoint. The gene, which was found to be encoded by 16 exons with evidence of alternative splicing, spanned > or =220 kb of DNA at 7q31.3. Mutation screening of the entire coding region in a set of 27 unrelated autistic individuals failed to identify phenotype-specific variants, suggesting that coding region mutations are unlikely to be involved in the etiology of autism. Apparent homologues of RAY1 have also been identified in mouse, rat, pig, chicken, fruit fly, and nematode. The human and mouse genes share similar splicing patterns, and their predicted protein products are 98% identical.

Alternative Splicing↗
PubMed2000

An unstable trinucleotide-repeat region on chromosome 13 implicated in spinocerebellar ataxia: a common expansion locus.

Larger CAG/CTG trinucleotide-repeat tracts in individuals affected with schizophrenia (SCZ) and bipolar affective disorder (BPAD) in comparison with control individuals have previously been reported, implying a possible etiological role for trinucleotide repeats in these diseases. Two unstable CAG/CTG repeats, SEF2-1B and ERDA1, have recently been cloned, and studies indicate that the majority of individuals with large repeats as detected by repeat-expansion detection (RED) have large repeat alleles at these loci. These repeats do not show association of large alleles with either BPAD or SCZ. Using RED, we have identified a BPAD individual with a very large CAG/CTG repeat that is not due to expansion at SEF2-1B or ERDA1. From this individual's DNA, we have cloned a highly polymorphic trinucleotide repeat consisting of (CTA)n (CTG)n, which is very long ( approximately 1,800 bp) in this patient. The repeat region localizes to chromosome 13q21, within 1.2 cM of fragile site FRA13C. Repeat alleles in our sample were unstable in 13 (5.6%) of 231 meioses. Large alleles (>100 repeats) were observed in 14 (1. 25%) of 1,120 patients with psychosis, borderline personality disorder, or juvenile-onset depression and in 5 (.7%) of 710 healthy controls. Very large alleles were also detected for Centre d'Etude Polymorphisme Humaine (CEPH) reference family 1334. This triplet expansion has recently been reported to be the cause of spinocerebellar ataxia type 8 (SCA8); however, none of our large alleles above the disease threshold occurred in individuals either affected by SCA or with known family history of SCA. The high frequency of large alleles at this locus is inconsistent with the much rarer occurrence of SCA8. Thus, it seems unlikely that expansion alone causes SCA8; other genetic mechanisms may be necessary to explain SCA8 etiology.

Adult↗
PubMed1999

D2 dopamine receptor but not AMPA and kainate glutamate receptor genes show altered expression in response to long term treatment with trans- and cis-flupenthixol in the rat brain.

Glutamate receptor function has been hypothesized as an important factor in both the aetiology and treatment of schizophrenia. We have used a multiprobe oligonucleotide solution hybridization (MOSH) technique to examine the regulation of gene expression of the GluR1-7, KA1, and KA2 glutamate receptor subunits in the left rat brain following treatment with the optical isomers of flupenthixol at a dose of 0.2 mg kg-1 day-1 over a period of 4, 12, 24 weeks in order to understand how specific glutamate receptor genes are involved in the treatment of schizophrenia. The GluR2/3 and GluR6/7 subunit immunoreactivity in the right brain following 4 and 24 weeks of drug treatment was also examined by Western blotting. Neither trans- nor cis-flupenthixol was found to alter the gene expression of any of the 9 non-NMDA glutamate receptor subunits. On the other hand, we found a nearly two-fold increase in gene expression of the D2 dopamine receptor in specific brain regions. These results suggest that non-NMDA types of glutamate receptor subunits, in contrast to NMDA receptors, are less likely to have a role in the action of antipsychotic drugs.

Amino Acid Sequence↗
PubMed1999

Cationic liposome-mediated DNA transfection in organotypic explant cultures of the ventral mesencephalon.

We have examined the potential of cationic liposomes as a tool for approaches to gene therapy in the CNS. Our previous work has shown that cationic liposomes formulated from 3 beta-[N-(N',N'-dimethylaminoethane)carbamoyl] cholesterol (DC-Chol) and dioleoyl-L-alpha-phosphatidylethanolamine (DOPE) could achieve high transfection levels in a neuronal cell line (McQuillin et al. Neuroreport 1997; 8: 1481-1484). We therefore wished to assess transfection efficiencies in organotypic cultures from the brain with a reporter plasmid expressing E. coli beta-galactosidase in order to mimic an in vivo model. Explant cultures were generated according to the method of Stoppini et al (J Neurosci Meth 1991; 37: 173-182) with slight modifications. Brain slices were maintained on transparent porous membranes and were observed to maintain their intrinsic connectivity and cytoarchitecture to a large degree over periods of up to 6 weeks in culture. CNS tissue was obtained from rats at birth or 5 days after birth. After transfection beta-galactosidase expression was detected in cells of both neuronal and non-neuronal morphology. Control cultures were exposed to liposome alone and a plasmid that had the beta-galactosidase gene insert removed. Only low levels of endogenous beta-galactosidase reactivity were seen in these control cultures. DC-Chol/DOPE-mediated transfection was confirmed using a RT-PCR protocol capable of differentiating between untranscribed plasmid DNA and RNA generated from the transfected vector. These results suggest that cationic liposomes, particularly DC-Chol/DOPE liposomes, will be useful as delivery agents for gene transfer to CNS cells in vitro and possibly in vivo.

Animals↗
PubMed1999

No evidence for linkage of schizophrenia to DXS7 at chromosome Xp11.

There have been claims that a gene on the X chromosome may contribute to susceptibility to schizophrenia. Crow (1988) initially proposed that such a gene might lie in the pseudoautosomal region, but when evidence that weakened this hypothesis accumulated, he proposed that a susceptibility locus might be present elsewhere on the sex chromosomes instead. DeLisi et al. (1994) found a small nonsignificant positive lod score between the marker DXS7 and schizophrenia, but other failed to replicate this finding. Another study reported by Crow and DeLisi's group was also weakly positive for this marker (Dann et al., 1997). This locus was then investigated in a collaborative study by Laval et al. (1997), which produced a nonparametric lod score of 2.44. Using a sample of 17 pedigrees from Britain and Iceland, we have also tested the hypothesis of linkage between DXS7 and schizophrenia. The 17 families were selected from a larger sample on the basis of an absence of male-to-male transmission for schizophrenia. These families were originally selected for having multiple cases of schizophrenia within them and for having no cases of bipolar affective disorder. We genotyped subjects for a marker at DXS7 and performed classical lod score and model-free linkage analysis using broad and narrow definitions of affection with schizophrenia. We found strongly negative lod scores and no evidence for linkage using model-free analysis. Therefore, this study does not support the hypothesis of linkage of schizophrenia to DXS7, and the evidence for a susceptibility locus on this part of the X chromosome is weakened.

Chromosome Mapping↗
PubMed1999

Genetic association analysis of serotonin system genes in bipolar affective disorder.

OBJECTIVE: This study examined the putative role of serotonin genes in the etiology of bipolar affective disorder. METHOD: Genetic association analysis was performed for individuals with bipolar affective disorder and unaffected subjects closely matched in age, sex, and ethnic background (N=103 in each group). The allele and genotype frequencies of polymorphisms at the genes for serotonin receptors HTR1A, HTR1Dalpha, HTR1Dbeta, HTR2A, HTR2C, HTR7, tryptophan hydroxylase (TPH), and the serotonin transporter (hSERT) were compared in the two groups of subjects. RESULTS: Statistically significant positive associations were found for HTR2A and hSERT polymorphisms. However, results from an independent replication group of over 100 patients with bipolar affective disorder and their matched comparison subjects failed to confirm these associations. CONCLUSIONS: These results suggest that the serotonin genes studied are not associated with bipolar affective disorder, although transmission disequilibrium studies are required in order to confirm this conclusion.

Adult↗
PubMed1998

No evidence of expansion of CAG or GAA repeats in schizophrenia families and monozygotic twins.

Many diseases caused by trinucleotide expansion exhibit increased severity and decreased age of onset (genetic anticipation) in successive generations. Apparent evidence of genetic anticipation in schizophrenia has led to a search for trinucleotide repeat expansions. We have used several techniques, including Southern blot hybridization, repeat expansion detection (RED) and locus-specific PCR to search for expanded CAG/CTG repeats in 12 families from the United Kingdom and 11 from Iceland that are multiplex for schizophrenia and demonstrate anticipation. The unstable DNA theory could also explain discordance of phenotype for schizophrenia in pairs of monozygotic twins, where the affected twin has a greater number of repeats than the unaffected twin. We used these techniques to look for evidence of different CAG/CTG repeat size in 27 pairs of monozygotic twins who are either concordant or discordant for schizophrenia. We have found no evidence of an increase in CAG/CTG repeat size for affected members in the families, or for the affected twins in the MZ twin sample. Southern hybridization and RED analysis were also performed for the twin and family samples to look for evidence of expansion of GAA/TTC repeats. However, no evidence of expansion was found in either sample. Whilst these results suggest that these repeats are not involved in the etiology of schizophrenia, the techniques used for detecting repeat expansions have limits to their sensitivity. The involvement of other trinucleotide repeats or other expandable repeat sequences cannot be ruled out.

Base Sequence↗
PubMed1998

Gene expression studies of mRNAs encoding the NMDA receptor subunits NMDAR1, NMDAR2A, NMDAR2B, NMDAR2C, and NMDAR2D following long-term treatment with cis-and trans-flupenthixol as a model for understanding the mode of action of schizophrenia drug treatment.

It has been hypothesized that glutamate receptor function is important in both the aetiology and treatment of schizophrenia. In order to understand how specific glutamate receptor genes are involved in the treatment of schizophrenia we have used a multiprobe oligonucleotide solution hybridization (MOSH) technique to examine the regulation of gene express of the NMDAR1, 2A, 2B, 2C, 2D receptor subunits in the left rat brain following treatment with the optical isomers of flupenthixol. cis- and trans-flupenthixol are both present in the commonly used oral and depot treatments for schizophrenia and a controlled trial showed that cis-flupenthixol had a significantly superior ability to ameliorate the positive symptoms of schizophrenia compared to its trans-isomer. At a dose of 0.2 mg/kg/day over a period of 1, 2, 4, 8, 12 and 24 weeks, we found that both isomers down regulated the expression of NMDAR1 mRNA in most regions of the brain. NMDAR2A, 2B and 2C receptor subunits showed a significantly decreased expression from 12 to 24 weeks but after 2 weeks NMDAR2B, 2C, 2D expression was increased in several brain regions. The NMDAR1 receptor subunit immunoreactivity in the right brain following 4 and 24 weeks of drug treatment was also examined by Western blotting. Both trans- and cis-flupenthixol significantly decreased the NR1 immunoreactivity in the right cerebellum after 24 weeks of treatment. These results suggest that NMDA receptor subunits may have a role in the action of antipsychotic drugs. If we assume that the NMDA receptor expression changes reflect a beneficial and significant mechanism in the treatment of schizophrenia, it could be argued that NMDA receptor changes are more related to the negative or non-specific symptoms of schizophrenia.

Administration, Oral↗
PubMed1997

Neuroreceptor subunit genes and the genetic susceptibility to Gilles de la Tourette syndrome.

Segregation studies have shown that Gilles de la Tourette Syndrome (GTS) is probably transmitted as an autosomal dominant gene disorder and can therefore be studied by classical linkage analysis to identify susceptibility loci. Many neurotransmitter systems have been implicated in the etiology of GTS. Most recently the alpha-1 subunit of the glycine receptor etiologically responsible for hyperekplexia has been hypothesized as the cause of the susceptibility to GTS. Because of this and the high concentration of other neuroreceptor genes at 5q33-35, it was decided to study this region and the associated gene cluster on chromosome 4p12-16 in a large British kindred multiply affected with GTS and chronic motor tics. The genotypes of the microsatellite markers at these loci were determined by polymerase chain reaction. The allele data were analyzed using both parametric and nonparametric methods. Approximate multipoint maps were constructed across the regions of interest using FASTLINK. All of the lod scores produced were negative, showing no evidence of linkage to GTS in the family studied. The multipoint maps showed good exclusion across these regions. The glycine receptor gene responsible for hyperekplexia and the other neuroreceptor genes examined in this paper are not involved in the etiology of GTS in this large pedigree.

Alleles↗
PubMed1997

Optimization of liposome mediated transfection of a neuronal cell line.

A cell line derived from sensory neurons was transfected with high efficiency using cationic liposomes, formulated from 3 beta [N-(N',N'-dimethylaminoethane)carbamoyl]-cholesterol (DC-Chol) and dioleoyl L-alpha-phosphatidylethanolamine (DOPE). This is the first time that cationic liposomes of this type have been reported to transfect a neuronal cell line. We used a reporter gene construct expressing beta-galactosidase under the control of the cytomegalovirus immediate early promoter and routinely observed transfection efficiencies > 40%. Parameters affecting transfection efficiency were examined and the ratio of DNA to liposome proved to be crucial. Liposome formulation procedures and cell transfection protocols devised here will be used as a basis for further in vivo and in vitro work.

Animals↗
PubMed1997

Exclusion of linkage between schizophrenia and the gene encoding a neutral amino acid glutamate/aspartate transporter, SLC1A5.

An abnormality in glutamatergic function has been hypothesized as being of etiological importance in schizophrenia. Twenty-three multiplex English and Icelandic schizophrenia families were genotyped with a polymorphic dinucleotide repeat sequence in the 3'-untranslated region of the glutamate/aspartate transporter gene called SLC1A5. Using the lod and a model-free method of linkage analysis (MFLINK), no evidence of linkage between SLC1A5 and schizophrenia was found. Our results do not support the hypothesis that SLC1A5 gene mutations or allelic variants provide a major gene contribution to the etiology of schizophrenia. However, because of the likelihood of heterogeneity of linkage in schizophrenia, there is a case for testing other pedigrees for linkage to the SLC1A5 locus. The SLC1A5 locus is one of a complex family of genes encoding neutral amino acid transporter proteins and the genetic relation between these other loci and schizophrenia has not yet been established.

Alleles↗