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Biomedical subjects

N Nouri

Publications and source records attributed to N Nouri.

At least 19 recordsLinked to original sources
PubMed2005

Lower oesophageal sphincter pressure and timed barium oesophagogram: two objective parameters in the non-invasive assessment of primary achalasia.

BACKGROUND: The non-invasive assessment of primary achalasia is not precise. AIM: To compare investigations before and 1 month after balloon dilation in achalasia. METHODS: Fifty-two patients with primary achalasia were enrolled. Subjective and objective variables of oesophageal functions were analysed before and 1 month after balloon dilation. RESULTS: The mean predilation symptom score, lower oesophageal sphincter pressure, height and volume of barium at 5 min were 7.7 +/- 2.6, 62.0 +/- 25.1 mmHg, 9.2 +/- 6.1 cm and 53.2 +/- 49.8 mL respectively; the mean postdilation values were 3.0 +/- 3.0, 34.1 +/- 12.5 mmHg, 7.9 +/- 5.1 cm and 28.0 +/- 30.1 mL respectively. The before dilation volume of barium at 5 min correlates significantly with lower oesophageal sphincter pressure (P < 0.01). The mean symptom scores, lower oesophageal sphincter pressure and volume of barium at 5 min dropped significantly after intervention (P < 0.01), but the reduction in barium height at 5 min was not significant. The percentage changes in volume at 5 min significantly predicted the percentage changes in lower oesophageal sphincter pressure (P < 0.01). CONCLUSIONS: The volume of barium retention at 5 min can predict the lower oesophageal sphincter pressure before and after balloon dilation in primary achalasia. This could be used as a non-invasive objective tool for initial and post-dilation assessment.

Adult↗
PubMed1999

Absence of linkage and linkage disequilibrium to chromosome 15q11-q13 markers in 139 multiplex families with autism.

Chromosomal region 15q11-q13 has been implicated to harbor a susceptibility gene or genes underlying autism. Evidence has been derived from the existence of cytogenetic anomalies in this region associated with autism, and the report of linkage in a modest collection of multiplex families. Most recently, linkage disequilibrium with the marker GABRB3-155CA2 in the candidate locus GABRB3, located in this region, has been reported. We searched for linkage using eight microsatellite markers located in this region of chromosome 15 in 147 affected sib-pairs from 139 multiplex autism families. We also tested for linkage disequilibrium in the same set of families with the same markers. We found no evidence for excess allele sharing (linkage) for the markers in this region. Also, we found no evidence of linkage disequilibrium, including for the locus GABRB3-155CA2. Thus, it appears that the role of this region of chromosome 15 is minor, at best, in the majority of individuals with autism.

Adolescent↗
PubMed1999

Exclusion of linkage to the HLA region in ninety multiplex sibships with autism.

Several studies have suggested a role for the histocompatibility complex of loci (HLA) in the genetic susceptibility to autism. We have tested this hypothesis by linkage analysis using genetic marker loci in the HLA region on chromosome 6p in multiplex families with autism. We have examined sharing of alleles identical by descent in 97 affected sib pairs from 90 families. Results demonstrate no deviation from the null expectation of 50% sharing of alleles in this region; in fact, for most marker loci, the observed sharing was less than 50%. Thus, it is unlikely that loci in this region contribute to the genetic etiology of autism to any significant extent in our families.

Adolescent↗
PubMed1999

A genomic screen of autism: evidence for a multilocus etiology.

We have conducted a genome screen of autism, by linkage analysis in an initial set of 90 multiplex sibships, with parents, containing 97 independent affected sib pairs (ASPs), with follow-up in 49 additional multiplex sibships, containing 50 ASPs. In total, 519 markers were genotyped, including 362 for the initial screen, and an additional 157 were genotyped in the follow-up. As a control, we also included in the analysis unaffected sibs, which provided 51 discordant sib pairs (DSPs) for the initial screen and 29 for the follow-up. In the initial phase of the work, we observed increased identity by descent (IBD) in the ASPs (sharing of 51.6%) compared with the DSPs (sharing of 50.8%). The excess sharing in the ASPs could not be attributed to the effect of a small number of loci but, rather, was due to the modest increase in the entire distribution of IBD. These results are most compatible with a model specifying a large number of loci (perhaps >/=15) and are less compatible with models specifying </=10 loci. The largest LOD score obtained in the initial scan was for a marker on chromosome 1p; this region also showed positive sharing in the replication family set, giving a maximum multipoint LOD score of 2.15 for both sets combined. Thus, there may exist a gene of moderate effect in this region. We had only modestly positive or negative linkage evidence in candidate regions identified in other studies. Our results suggest that positional cloning of susceptibility loci by linkage analysis may be a formidable task and that other approaches may be necessary.

Adolescent↗
PubMed1997

Comparative studies of the CAG repeats in the spinocerebellar ataxia type 1 (SCA1) gene.

The CAG repeat tract at the autosomal dominant spinocerebellar ataxia type 1 (SCA1) locus was analyzed in SCA1 families and French-Acadian, African-American, Caucasian, Greenland Inuit, and Thai populations. The normal alleles had 9-37 repeats, whereas disease alleles contained 44-64 repeats. The CAG repeat tract contained one or two CAT interruptions in 44 of 47 normal human chromosomes and in all five chimpanzees examined. In contrast, no CAT interruptions were found in Old World monkeys or expanded human alleles. The number and positions of CAT interruptions may be important in stabilizing CAG repeat tracts in normal chromosomes. At least five codons occupy the region corresponding to the polyglutamine tract at the SCA1 locus in mice, rats, and other rodents. They comprise three or four CCN (coding for proline) in addition to one or two CAG repeats.

Amino Acid Sequence↗
PubMed1996

Analysis of CAG repeat of the Machado-Joseph gene in human, chimpanzee and monkey populations: a variant nucleotide is associated with the number of CAG repeats.

Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder associated with an unstable and expanded CAG repeat. We analyzed this locus from various sources including MJD families, Acadian, African American, Caucasian, Greenland Inuit and Thai populations. The range of the CAG repeat size was 14-40 in the normal alleles while the MJD alleles contained 73-78 repeats in our studies. We found 25 different alleles on normal chromosomes with a heterozygosity of 0.86 in combined populations. The most common alleles were 23 (22.9%) and 14 (25.5%) repeats. We also examined 16 chimpanzees and various Old World monkeys: a pigtail macaque, a mangabey and 12 rhesus macaques. The DNA sequences surrounding the CAG repeat did not vary among species. The range of the number of the CAG repeats is 13-14 in macaques, 16 in mangabey and 14-20 in chimpanzees. Variant CAA or AAG triplets in the CAG repeat tracts were found in all 268 human, 28 monkey and 32 chimpanzee chromosomes. As reported in a previous study [Kawaguchi et al. (1994) Nature Genet. 8, 221-228] the common variant positions were the third (CAA), fourth (AAG) and sixth (CAA) positions. However, we found three human chromosomes containing CAG at the sixth position and the mangabey had AAG at the ninth position. In addition, we found CAG at the fourth position and AAG at the sixth position in all macaque chromosomes. The nucleotide following the CAG repeat tract was usually G in all species studied. However, we sometimes found C at this position in human and chimpanzee chromosomes. Interestingly, this variant C was found in all expanded chromosomes and in 54.5% of chromosomes with 27-40 CAG repeats but it was not found in any chromosomes with less than 20 CAG repeats. We hypothesize that the variant C may be associated with CAG repeat instability.

Animals↗
PubMed1995

A locus for axonal motor-sensory neuropathy with deafness and mental retardation maps to Xq24-q26.

DNA markers on the X chromosome were used to map the locus for an unusual form of X-linked recessive hereditary motor and sensory neuropathy with associated deafness and mental retardation in a three-generation family that was originally reported by Cowchock et al. (Am, J. Hum. Genet. 35: 85A, 1993; Am. J. Med. Genet. 20: 307-315, 1985). This family included seven affected males, three obligate carrier females, and four unaffected males. The patients were severely affected within the first few years of life with distal weakness, muscle atrophy, sensory loss, areflexia, pes cavus, and hammer toes. Five of the seven affected males showed associated deafness, and three of these five individuals also presented with mental retardation or social developmental delay. Motor nerve conduction velocities in affected males were normal to mildly delayed, and sensory conduction was markedly abnormal. Heterozygous females were asymptomatic. Close linkage to the Xg blood group locus (Xp22) and the PGK locus (Xq13) was previously excluded in this family, while weak linkage of the disease gene to DXYS1 (XQ21.3) was suggested. Our current linkage studies and haplotype analysis of 19 microsatellite markers on the long arm of the X chromosome demonstrate that DXS425 (Xq24) and HPRT (Xq26.1) are flanking markers and that the disease gene is closely linked to the markers DXS1122, DXS994, DXS737, DXS1206, and DXS1047.

Chromosome Mapping↗
PubMed1995

The deafness locus (dn) maps to mouse chromosome 19.

The deafness mouse has profound sensorineural hearing loss with degeneration of hair cells soon after birth. The mode of inheritance is recessive, and there are no associated phenotypic anomalies. Thus, this mouse provides a model for recessive, non-syndromic, prelingual deafness. We have mapped the gene causing deafness in the mouse to Chromosome (Chr) 19 by analysis of 230 intersubspecific backcross progeny. No recombinants were found with the microsatellite marker D19Mit14. The loci for two guanine nucleotide-binding proteins are tightly linked to this marker, and they are being investigated as possible candidate genes. The identification of the defective gene in the mouse will help to explain the mechanism that causes hair cell degeneration and is likely to identify a homologous gene for deafness in humans.

Animals↗
PubMed1995

Mapping of the gene for hormone sensitive lipase (LIPE) to chromosome 19q13.1-->q13.2.

Free fatty acids are the major source of fuel for mammals, and hormone sensitive lipase (LIPE) plays a critical role in lipid metabolism by mobilizing free fatty acids from stored triglycerides. We have identified and sequenced a partial cDNA for LIPE. Cosmids were identified by hybridization and mapped to 19q13.1-->q13.2 by FISH. Direct sequence analysis of a 1 kb segment of cosmid 26710 identifies a dinucleotide repeat in an intron upstream of exon 8 of human LIPE. This marker was heterozygous 82% of the time with 12 alleles (166-190 bp) detected in 122 chromosomes. The most likely order for this gene is: qter-[D19S178/LIPE]-(3 cM)-D19S47-(1 cM)-D19S190-RYR1-cen.

Alleles↗
PubMed1994

A gene for Crouzon craniofacial dysostosis maps to the long arm of chromosome 10.

Crouzon craniofacial dysostosis (CFD) is an autosomal dominant craniofacial disorder characterized by premature craniosynostosis, shallow orbits and hypoplastic maxilla. To map the gene responsible, we have used a mapping strategy of testing for linkage to known developmental genes. Analysis of a large kindred established linkage between CFD and three loci (D10S190, D10S209 and D10S216) that span a 13 cM region on chromosome 10q. A maximum pairwise lod score of 4.42 (theta = 0) at D10S190 was obtained and the addition of a second kindred produced a combined pairwise lod score of 5.32 (theta = 0) at the same locus. The developmental gene, PAX2, located within this region, is an attractive candidate gene.

Chromosome Mapping↗
PubMed1994

Tightly linked flanking microsatellite markers for the Usher syndrome type I locus on the short arm of chromosome 11.

Usher syndrome type I is an autosomal recessive disease characterized by profound congenital hearing impairment and vestibular dysfunction followed by the onset of progressive pigmentary retinopathy in childhood or early adolescence. A locus (USH1C) for one form of this disease was previously assigned to the short arm of chromosome 11 through linkage studies in the Acadian population of southwestern Louisiana. Linkage analyses of a set of microsatellite markers in 27 Acadian families provide evidence that USH1C lies between D11S861 and D11S928. Three markers (D11S419, D11S921, and D11S899) that lie between the flanking markers show no recombination with USH1C, and all 54 chromosomes with the abnormal allele at the disease locus have identical alleles for D11S419 and D11S921. This haplotype was found on only 10 of 50 chromosomes with the normal allele at the disease locus, suggesting a strong founder effect. Of the 54 chromosomes with the abnormal allele, 12 had a divergent allele at D11S899. These results suggest that USH1C is in the 2-3-cM interval between D11S861 and D11S899.

Chromosomes, Human, Pair 11↗
PubMed1993

Linkage mapping of the human thromboxane A2 receptor (TBXA2R) to chromosome 19p13.3 using transcribed 3' untranslated DNA sequence polymorphisms.

The actions of thromboxane A2 as a prostaglandin mediator are dependent on its recently cloned and sequenced receptor. The identification and characterization of DNA polymorphisms in the thromboxane A2 receptor (TBXA2R) will advance the study of this gene as a candidate in a number of medical disorders. We amplified a 573-nucleotide fragment of the transcribed 3' untranslated region of the TBXA2R gene using the polymerase chain reaction (PCR) and the published cDNA sequence. This region was found to contain two sequence polymorphisms within an Alu. These DNA polymorphisms were demonstrated using an efficient method of direct solid-phase sequence analysis. Three of the four expected alleles were observed in the CEPH families. TBXA2R was localized to chromosome 19 by PCR amplification in a series of monochoromosomal human/rodent somatic cell hybrids. Linkage mapping places TBXA2R closest to the anonymous marker D19S120, with a maximal LOD = 19.55, at a theta = 0.05 in the CEPH panel of DNAs. Multipoint linkage analysis places TBXA2R between the markers D19S120 and PMS207 on the telomeric end of chromosome 19p13.3.

Base Sequence↗
PubMed1991

Evidence for genetic heterogeneity in malignant hyperthermia susceptibility.

Malignant hyperthermia susceptibility (MHS) is a clinically heterogeneous pharmacogenetic disorder characterized by accelerated metabolism, hyperthermia, and frequently muscle rigidity. MHS is elicited by all commonly used potent inhalation anesthetics and depolarizing neuromuscular blockers and remains an important cause of death due to anesthesia. Recent linkage studies suggest a single genetic locus for this disorder on chromosome 19q13.1. The results of our linkage analyses exclude several loci on 19q13.1 as a site for the gene(s) that produces the MHS phenotype in three unrelated families and clearly establish genetic heterogeneity in this disorder. These results are consistent with the hypothesis that the genetic defect that alters thermoregulation may vary in MHS and that clinical variability in the expression of MHS may be explained by genetic heterogeneity.

Chromosomes, Human, Pair 19↗
PubMed1987

Pleiotropic changes in cycloheximide-resistant insect cell clones.

Somatic cell mutants resistant to drugs that interact with the eukaryotic ribosome provide a useful tool for studies on ribosome structure, function, and genetics. From Aedes albopictus (mosquito) cells, cycloheximide-resistant mutants (Cx-705 and Cx-738) that were about 30-fold more resistant to cycloheximide than the parental cells have been obtained. The observation that protein synthesis in cell-free lysates from Cx-705 and Cx-738 cells was resistant to cycloheximide led us to suspect that the alteration in these mutants might affect the ribosome. The present studies show that the cycloheximide-resistant cells grow poorly and eventually die at 34.5 degrees C, a temperature at which wild-type cells grow normally. Relative to control cells, the cycloheximide-resistant cells show increased sensitivity to G-418, another antibiotic that interacts with the eukaryotic ribosome. However, there were no differences between cycloheximide-resistant cells and wild-type cells in sensitivity to puromycin, emetine, or cryptopleurine. Cx-705 cells were predominantly diploid; in contrast, the frequency of tetraploid nuclei in Cx-738 cells was about 40%.

Aedes↗
PubMed1979

Incidence and significance of candiduria.

The 100,000 colony count has been used without careful evaluation for the diagnosis of renal candidiasis. Therefore, a prospective study was done on 1,004 urine samples from patients without signs of candidiasis to determine the incidence of candiduria and Candida colony counts. These were compared with colony counts from histologically proved cases of renal candidiasis. The incidence of candiduria varied from a low of 4% in men to a high of 39% in girls during their second week of antibiotic therapy. The overall mean colony count was 1,292 +/- 1,500. The mean colony count in clean-catch urine specimens from six proved cases of renal candidiasis was 23,750 +/- 12,311. The difference in colony counts from proved and unproved cases is statistically significant. Counts greater than 10,000 Candida organisms per milliliter require further investigation.

Adult↗