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Biomedical subjects

G Turner

Publications and source records attributed to G Turner.

At least 127 records · Page 7Linked to original sources
PubMed1996

Expression of alternatively spliced isoforms of the parathyroid hormone (PTH)/PTH-related peptide receptor messenger RNA in human kidney and bone cells.

Using a PCR-based strategy, two variants of the PTH/PTH-related peptide (PTH-rp) receptor mRNA were identified in human kidney, SaOS-2 human osteoblast cells, and rat bone that are produced by alternative splicing of exons coding for the N-terminal portion of the receptor. In the S-N3-E2 isoform, the exon coding the signal peptide (S) is spliced to an alternative 3'-acceptor site, producing a product respecting the reading frame, but in which the E1 exon is replaced by 12 amino acids derived from the N3 intron. In the S-E2 isoform, in which the E1 exon is deleted by cassette exclusion, the reading frame is changed, but a truncated receptor may be produced by reinitiation of translation at an overlapping stop/start codon. After transfection of COS and Chinese hamster ovary cells with the originally described S-E1-E2 isoform and the two splice variants, active transcription of PTH/PTH-rp receptor mRNA was detected by RT-PCR in all cases. Cell lines transfected with the S-E1-E2 and S-N3-E2 isoforms displayed a 15- to 25-fold and 2- to 3-fold increase, respectively, in cAMP content after stimulation with 2.4 x 10(-7) M human PTH(1-34), whereas cells transfected with the S-E2 isoform did not respond. PTH elicited an increase in intracellular calcium only in cells transfected with the S-E1-E2 isoform. Studies evaluating the surface expression of receptors using anti-human PTH/PTH-rp receptor antibodies and the ability of transfected cells to bind [125I]PTH-rp indicated that the low or absent responses to PTH stimulation resulted, at least in part, from low surface expression of the S-N3-E2 and S-E2 isoforms. These studies support the conclusion that exon E1 is extremely important in promoting surface expression of the PTH/PTH-rp receptor but indicate that isoforms lacking this exon can retain the ability to recognize PTH. The possible intracellular expression of these splice variants, which account for 15-20% of total PTH/PTH-rp receptor mRNA, needs to be evaluated.

Alternative Splicing↗
PubMed1996

Development and evaluation of a classification of high risk youths entering a juvenile assessment center.

We report the results of developing and evaluating a classification of high risk youth entering a Juvenile Assessment Center in Hillsborough County, Florida, involving over 2,000 youths processed at the center during its first 8 months of operation. Cluster analysis of the youths' potential problems probed by the Problem Oriented Screening Instrument for Teenagers defined four groups. The usefulness of the typology was supported by a discriminant analysis and by recidivism information. The research implications of these results are discussed.

Adolescent↗
PubMed1996

Examination of the reliability of the Problem Oriented Screening Instrument for Teenagers (POSIT) among arrested youths entering a juvenile assessment center.

The Problem Oriented Screening Instrument for Teenagers (POSIT) serves as a key aspect of the preliminary screening activities at the Hillsborough County Juvenile Assessment Center. We report on a reliability study of POSIT, involving an examination of the relationships between the youths' initial and second admission POSIT results for different time intervals between administration of the instrument. The results indicate the POSIT provides consistent indication of potentially troubled youths who are in need of in-depth assessment and intervention or treatment services.

Adolescent↗
PubMed1996

Affected-sib-pair analyses reveal support of prior evidence for a susceptibility locus for bipolar disorder, on 21q.

In 22 multiplex pedigrees screened for linkage to bipolar disorder, by use of 18 markers on chromosome 21q, single-locus affected-sib-pair (ASP) analysis detected a high proportion (57%-62%) of alleles shared identical by descent (IBD), with P values of .049-.0008 on nine marker loci. Multilocus ASP analyses revealed locus trios in the distal region between D21S270 and D21S171, with excess allele sharing (nominal P values <.01) under two affection-status models, ASM I (bipolars and schizoaffectives) and ASM II (ASM I plus recurrent unipolars). In addition, under ASM I, the proximal interval spanned by D21S1436 and D21S65 showed locus trios with excess allele sharing (nominal P values of .03-.0003). These findings support prior evidence that a susceptibility locus for bipolar disorder is on 21q.

Bipolar Disorder↗
PubMed1996

Expression of full-length human dystrophin cDNA in mdx mouse muscle by HVJ-liposome injection.

Duchenne muscular dystrophy (DMD) is an X-linked progressive muscle disorder which is caused by a defect of dystrophin, a 427-kDa muscle cell membrane protein. One of the possible means of DMD therapy is to express the dystrophin gene in patients' muscles. In this study, full length dystrophin cDNA was expressed in mdx (muscular dystrophy model) mouse muscle using the hemagglutinating virus of Japan (HVJ)-liposome method. With the HVJ-liposome method, the lacZ reporter genes were expressed in 50-80% of cultured mdx mouse myoblasts, which suggested its potential usefulness for an in vivo gene study. Three expression vectors containing human full length dystrophin cDNA driven by Rous sarcoma virus (RSV), mouse leukemia virus, or human dystrophin promoters, were used. HVJ-liposomes containing these plasmids were directly injected into mdx mouse quadriceps muscle. The highest efficiency of expression of dystrophin was in 26% of the muscle fibers at the injected site on day 3 after HVJ-liposome injection of the RSV-based vector. The expression was decreased on day 10. The study thus demonstrates the feasibility of full length human dystrophin cDNA transfer and dystrophin expression using HVJ-liposomes in vivo.

Animals↗
PubMed1996

Investigating paediatric airways by non-bronchoscopic lavage: normal cellular data.

BACKGROUND: Bronchoscopic bronchoalveolar lavage in children to investigate bronchial disorders such as asthma has both ethical and procedural difficulties. OBJECTIVE: The aim of this study was to establish a standardized non-bronchoscopic method to perform bronchoalveolar lavage in children attending for elective surgery to obtain normal cellular data. METHODS: Bronchoalveolar lavage was performed on normal children (n = 55) by infusing saline (20 mL) through an 8 FG suction catheter passed after endotracheal intubation. Oxygen saturation, heart and respiratory rate were monitored during the bronchoalveolar lavage procedure. Cellular analysis and total protein estimation of the lavage fluid were performed. Epithelial lining fluid volume was calculated (n = 15) using the urea dilution method. RESULTS: The procedure was well tolerated by all children. Total cell count and differential cell count for children (macrophages 70.8 +/- 2.3%, lymphocytes 3.8 +/- 0.6%, neutrophils 5.7 +/- 1.0%, eosinophils 0.14 +/- 0.03%, epithelial cells 19.6 +/- 2.1%, mast cells 0.21 +/- 0.02%) were similar to those reported for adults. Age and sex comparisons revealed no differences between groups. The mean total protein recovered in the cell free supernatant was 49.72 +/- 4.29 mg/L and epithelial lining fluid volume was 0.82 +/- 0.11% of return lavageate. CONCLUSION: This method allows bronchoalveolar lavage to be performed safely and quickly on children attending for routine elective surgery. Using this method and taking the 'window of opportunity' of elective surgery, the presence or absence of airway inflammation could be studied in children with various patterns of asthma during relatively asymptomatic periods.

Adolescent↗
PubMed1995

The Tay-Sachs disease prevention program in Australia: Sydney pilot study.

OBJECTIVES: To determine the frequency of heterozygous carriers of the Tay-Sachs disease gene in an asymptomatic Ashkenazi Jewish population and to compare the acceptability of different community testing strategies. DESIGN: Pilot survey of carrier rates and community attitudes. SETTING: Sydney, February 1993 to November 1994. PARTICIPANTS: 147 self- or medically referred people of Ashkenazi Jewish origin were tested. Jewish religious, medical and community organisations and leaders were consulted. OUTCOMES: Prevalence of HEXA mutations, client and community preference for different testing and reporting strategies. RESULTS: Frequency of heterozygous carriers was 1 in 18, with a relative frequency of the three major allelic variants similar to that in overseas studies. Most subjects were medically referred and preferred individual reporting of their carrier status. Community representatives had serious reservations about this strategy and few orthodox Jews participated in the study. An alternative strategy was developed for future testing. CONCLUSIONS: Frequency of heterozygous carriers of the Tay-Sachs disease gene was higher than found among Ashkenazi Jews in other countries, possibly because of ascertainment bias. A testing strategy with medical referral and individual reporting of carrier status may not be appropriate for all the community at risk and a modified strategy is necessary.

Genetic Testing↗
PubMed1995

Adrenocorticotropin receptor/melanocortin receptor-2 maps within a reported susceptibility region for bipolar illness on chromosome 18.

We have examined the possible linkage of adrenocorticotropin receptor/melanocortin receptor-2 (ACTHR/MC-2) to a reported putative susceptibility locus for bipolar illness (BP) in 20 affected pedigrees. Initially, allelic variants of the gene were identified by polymerase chain reaction-single stranded conformation polymorphism (PCR-SSCP) and the gene was genetically mapped using both the Centre d'Etudes du Polymorphisme Humain (CEPH) pedigrees and the BP pedigrees used in this study. We found that the ACTHR/MC-2 gene maps between D18S53 and D18S66. These loci span a region of chromosome 18 which, in a previous study [Berrettini et al.: Proc Natl Acad Sci USA 91:5918-5921, 1994) revealed a putative predisposing locus to BP through nonparametric methods of linkage analysis. Linkage of ACTHR/MC-2 to BP was not demonstrable under parametric and nonparametric methods of analyses, although affected sib-pair (ASP) method revealed an increase in allele sharing among ill individuals, P = 0.023. Since this receptor is within a potential linkage region, ACTHR/MC-2 could be considered a candidate gene for BP.

Base Sequence↗
PubMed1995

Isolation and characterisation of genes for sulphate activation and reduction in Aspergillus nidulans: implications for evolution of an allosteric control region by gene duplication.

A region of the Aspergillus nidulans genome carrying the sA and sC genes, encoding PAPS reductase and ATP sulphurylase, respectively, was isolated by transformation of an sA mutant with a cosmid library. The genes were subcloned and their functions confirmed by retransformation and complementation of A. nidulans strains carrying sA and sC mutations. The physical distance of 2 kb between the genes corresponds to a genetic distance of 1 cM. While the deduced amino acid sequence of the sA gene product shows homology with the equivalent MET16 gene product of Saccharomyces cerevisiae, the sC gene product resembles the equivalent MET3 yeast gene product at the N-terminal end, but differs markedly from it at the C-terminal end, showing homology to the APS kinases of several microorganisms. It is proposed that this C-terminal region does not encode a functional APS kinase, but is responsible for allosteric regulation by PAPS of the sulphate assimilation pathway in A. nidulans, and that the ATP sulphurylase encoding-gene (sC) of filamentous ascomycetes may have evolved from a bifunctional gene similar to the nodQ gene of Rhizobium meliloti.

Adenosine Triphosphate↗
PubMed1995

A possible screening test for inherited p53-related defects based on the apoptotic response of peripheral blood lymphocytes to DNA damage.

The cellular response, in terms of cell cycle arrest(s) and apoptosis, to radiation-induced DNA damage was studied. Experiments were performed on both mitogen-stimulated and resting peripheral blood lymphocytes (PBLs) from normal and cancer-prone (C-P) individuals. The C-P individuals comprised three patients carrying germline p53 mutations and three members of two families apparently without such mutations, but with an inherited defect which results in p53 deregulation as shown by high levels of stabilised p53 protein in normal tissues. Interestingly, mitogen-stimulated PBL, from both normal and C-P individuals failed to demonstrate a G1 arrest after gamma radiation. However, a clear difference was seen in the apoptotic response to DNA damage, of PBL from normal and C-P individuals; PBLs from C-P individuals with inherited p53-related defects had a reduced apoptotic response (P = 0.0003). There was a wide margin of separation, with no overlap between the two groups, supporting the possibility of using this altered apoptotic response as a screening test. This simple and rapid procedure could be used to identify those individuals in a C-P family who carry germline p53-related defects. The method appears to detect both individuals with p53 mutations and those apparently without mutations but with other p53-related defects.

Adult↗
PubMed1995

Expression of human full-length and minidystrophin in transgenic mdx mice: implications for gene therapy of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a lethal X-linked recessive disorder with a high spontaneous mutation rate and no effective treatment, hence development of genetic based therapies is an important goal. We report that expression of a recombinant human minidystrophin cDNA, compatible with current viral vectors, can significantly reduce the myopathic phenotype in transgenic mdx mice, even when expressed at only 20-30% of endogenous dystrophin levels at the sarcolemma. To the extent that data obtained in mouse studies are applicable to DMD, the virtual elimination of morphological and biochemical abnormalities in the mdx mouse supports the use of this cDNA in somatic gene therapy protocols for DMD.

Animals↗
PubMed1995

Molecular defect of a phosphoglycerate kinase variant associated with haemolytic anaemia and neurological disorders in a large kindred.

The X-chromosome-linked phosphoglycerate kinase (PGK) deficiency associated with severe chronic and acute haemolytic anaemia and mental disorders was first described in a large Chinese kindred in 1969. The molecular abnormality of this original variant remained to be identified. The red cell PGK activity was only about 5%, but the activity of the patients' lymphoblastoid cells was about 15% of normal. The PGK mRNA content of the patients' lymphoblastoid cells were normal. Analysis of the patients' mRNA showed the existence of a nucleotide transversion A-->T at position 491 (counting from adenine of the initiation codon). The mutation should cause an amino acid substitution Asp-->Val at position 163 of the enzyme. The replacement of the acidic aspartic acid by a hydrophobic valine is expected to induce drastic structural instability resulting in severe enzyme deficiency in the patients' tissues. The genotypes of two affected males, their mothers and 22 females of the family were identified by the PCR-mediated method using their genomic DNA samples. 13/24 females examined were found to be variant heterozygous. In this large family, affected males over three generations have died at a pre-adult age. Post- and pre-natal genotyping of the family members may prevent future problems.

Anemia, Hemolytic, Congenital↗
PubMed1995

Heterogeneity in Li-Fraumeni families: p53 mutation analysis and immunohistochemical staining.

We have screened two families for constitutional TP53 mutations, one family with Li-Fraumeni syndrome and the other with features of this syndrome. We report a germline mutation in exon 7 of the TP53 gene in the family with "Li-Fraumeni-like" syndrome. The mutation occurred at codon 245 and causes a Gly-Ser amino acid change. It was inherited by both affected and unaffected subjects. Malignant tumours from all members of this family showed strong positive nuclear immunohistochemical staining with antibodies CM-1 and DO1, directed against TP53. In contrast, no constitutional TP53 mutations were found in a "classic" Li-Fraumeni family. In this family positive staining was seen in both malignant and normal tissues. These results support previous findings that variants of the Li-Fraumeni syndrome exist since not all LFS families carry TP53 germline mutations. Secondly, immunohistochemical positivity is not synonymous with an underlying mutation and is therefore inadequate as an exclusive diagnostic marker.

Adolescent↗