Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 4 uppsatser.

Familial lipoprotein lipase (LPL) deficiency is a rare disorder of lipid metabolism associated with massive chylomicronaemia. Patients often present early in life with abdominal pain, pancreatitis, hepatosplenomegaly, eruptive xanthomata and zero to near zero levels of LPL activity in post-heparin plasma. The genetic heterogeneity underlying this disease is well-characterised and over 40 mutations have been described at the LPL gene loci. In this report three mutations are described at the LPL locus in two unrelated probands, namely, JJ (Kindred I) and LB (Kindred II). JJ presented early in childhood with signs and symptoms suggestive of LPL-deficiency. These were abdominal pain, hepatosplenomegaly and a markedly reduced LPL activity (38% of normal) in post-heparin plasma. DNA studies showed JJ to be a compound heterozygote for two point mutations in the LPL gene, these being, the I194T and C418Y substitutions, which occur in exons 5 and 9, respectively. Several mutation detection systems were set up as part of the characterisation and screening workup for these mutations; these were, allele-specific oligo nucleotide (ASO) hybridisation, "ARMS" PCR, PCR-SSCP, RT-PCR and DNA sequence analysis. In an earlier separate study, in vitro transfection results showed that the I194T mutant was catalytically inactive. Our findings of zero LPL activity in JJ's post-heparin plasma, implies that the C418Y mutation is also likely to produce an inactive protein product. The differences in LPL activity observed during the pre- and post-pubertal stages, if not artefactual, may be due to differential processing of LPL during human development with loss of activity post puberty. LB was first diagnosed with pancreatitis during the third trimester of her pregnancy. Although her child, BB, was successfully delivered by caesarean section, LB died of haemorrhagic pancreatitis with the marked hyperlipidaemia being suggestive of an underlying deficiency in LPL activity. Genomic DNA from her parents was first subjected to mutation analysis, since only slide specimens of post-mortem material were available from LB. Maternal DNA revealed a 0-A transition at nucleotide position 1516 which results in the substitution of lysine for glutamic acid at codon 421 in exon 9 (E421K), while paternal DNA show a single polymorphism at codon 108 in exon 3 of the LPL gene. Analysis of archival DNA obtained from histopathological slides of spleen tissue from LB also showed the E421K mutation. This mutation was also detected in her offspring, BB indicating maternal inheritance in three generations. While, this mutation may produce a catalytically defective product, the evidence is insufficient to propose a role for LPL deficiency as the primary cause of death in this patient, hence the search for a second mutation in the LPL gene of LB is imperative to establish this association.

No description available.

Haemonchus contortus is a parasitic nematode that is controlled in large part by nematocidal drugs that target receptors of the parasitic nervous system. Hco-UNC-49 is a nematode GABA receptor that has a relatively low overall sequence homology to mammalian GABA receptors but is very similar to the UNC-49 receptor found in the free living nematode Caenorhabditis elegans. However, the nematode receptors do exhibit different sensitivities to GABA which may be linked to differences in the putative GABA binding domains. Mutational analysis conducted in this study identified at least one amino acid, positioned near the GABA binding domain, which may partially account for differences in nematode GABA sensitivity. In addition, positions reported to be crucial for GABA sensitivity in mammalian receptors also affect GABA sensitivity in Hco- UNC-49 suggesting that the GABA binding domains of the mammalian and nematode GABA receptors share some pharmacological similarities. However, there were some differences observed. For example, in mammalian GABAA receptors amino acids from both  and  subunits appear to be important for GABA sensitivity. For residues examined in this study, only those on the UNC-49B subunit, and not UNC-49C, appear important for GABA sensitivity. / UOIT

Diss. (sammanfattning) Linköping : Linköpings universitet, 2007. / Härtill 4 uppsatser.

Thesis (Ph. D.)--University of Washington, 1998. / Vita. Includes bibliographical references (leaves [104]-114).

by Chiu Wing Lok Abe Kurtz. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (p. 218-230). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

The CsgD protein is the master regulator of a pathway leading to the formation of curli, in essence regulating the switch between a motile and a sessile lifestyle for bacteria. The 5’-UTR region of the csgD mRNA is a hotspot for multiple regulatory small RNAs (sRNA) involved in a complex regulatory network. Even though it is previously known how the interaction takes place it is unknown how sRNA binding affects the translational activity. In order to suggest a mode of regulation a mutational assay was performed by making changes in the csgD 5’-UTR and investigate what the translational effects were. Mutations in different regions are shown to affect the translation levels in various ways.

Tuberous sclerosis complex (TSC) is an autosomal dominant disorder that affects several organs in the human body including the brain, heart, kidneys, eyes, skin, spleen, liver and lungs [Roach, et al., 1999]. TSC is characterized by hamartomas that rarely progress to malignancy in the affected organs. Clinical symptoms of TSC include cortical tubers and subependymal nodules in the brain, seizures, mental retardation, ungual and periungual fibromas, angiofibromas of the face, and angiomyolipomas in the kidneys [Roach, et al., 1999]. TSC displays genetic heterogeneity with two known loci: TSC1 on chromosome 9q34 [Fryer, et al., 1987a] and TSC2 on chromosome 16p13.3 [Kandt, et al., 1992]. The genes for both loci have been isolated and characterized [ The European Chromosome 16 Tuberous Sclerosis Consortium, 1993; van Slegtenhorst, et al., 1997]. The TSC1 gene contains 21 coding and two non-coding exons and encodes for an 8.6 kb mRNA. It spans 45 kb of genomic DNA and codes for hamartin, a 1,164 amino acid protein of 130 kDa. The TSC2 encodes for a 200 kDa protein, tuberin, and spans 43 kb of genomic DNA. The TSC2 gene consists of 41 coding exons and one non-coding exon and encodes for a 5.4 kb mRNA. Both genes are known to function as tumor suppressors [Carbonara, et al., 1994; Green, et al., 1994a; Green, et al., 1994b]. Several groups have performed mutation analysis of both the genes in patients mainly from the western and Japanese populations. A total of 133 mutations in the TSC1 gene and 350 mutations in the TSC2 gene have been reported so far (Human Gene Mutation Database; http://archive.uwcm.ac.uk/uwcm/mg/hgmd0.html). However, there is no report on the mutation analysis of the TSC genes from the Indian population. In this study, a total of 24 TSC cases were ascertained from the Indian population and a comprehensive mutation analysis of both the TSC genes was carried out in them to understand the function of both the genes, to locate important domains and also to find the mutational hotspots for molecular diagnosis of TSC. A total of 12 mutations, including seven novel mutations were identified. It was also shown that the most recurrent mutations (c.1831C>T and c.1832G>A) are, in part, due to methylation of the CpG dinucleotide. There are still 15-25% TSC cases in western populations with undetected mutations [Cheadle, et al., 2000a]. Further, there are familial TSC cases linked either to the TSC1 on 9q34 or TSC2 on 16p13.3 which fail to show any mutations in the coding sequences of both genes [Cheadle, et al., 2000a]. The failure to detect mutations in these cases could be due to several reasons. First, it could be that the mutations lie in the regulatory regions (promoters and enhancers) of both the genes, presently unidentified for the TSC1 gene [Cheadle, et al., 2000a]. Second, it is possible that the mutations lie outside of the coding sequences, within intronic sequences, or in the 5’ or 3’ UTRs [Cheadle, et al., 2000a]. Third, it may be due to the limitation of the techniques used to identify mutations [Cheadle, et al., 2000a]. In order to look for mutations in the promoter, the TSC1 gene promoter was characterized using luciferase reporter gene transfection assay. The promoter for the TSC2 gene is known [Kobayashi, et al., 1997]. The promoters of both TSC1 and TSC2 genes were sequenced in all the 24 cases to look for mutations. During the characterization of the TSC1 gene promoter, a novel isoform involving the non-coding exon 1 of the TSC1 gene was discovered serendipitously.

Thesis (Ph. D.)--University of Virginia, 2007. / Includes bibliographical references. Also available online through Digital Dissertations.