Biomedical subjects

D J Hall

Publications and source records attributed to D J Hall.

At least 73 records · Page 4Linked to original sources

PubMed1993

Downregulation of c-myc expression by antisense oligonucleotides inhibits proliferation of human smooth muscle cells.

BACKGROUND: Proliferation of smooth muscle cells (SMCs) plays an important role in vascular pathobiology, being involved in the development of coronary restenosis and atherosclerosis. The activation of nuclear proto-oncogenes appears to be a final common pathway onto which various mitogenic signals coverage. Accordingly, we attempted to determine whether the activation of the c-myc nuclear proto-oncogene is essential for human SMC proliferation and explored the possibility of inhibiting their growth using antisense oligonucleotides directed against c-myc messenger RNA (mRNA). METHODS AND RESULTS: Proliferation of human SMCs was associated with an increase in c-myc mRNA expression after growth stimulation. Using 15-mer phosphorothioate oligonucleotides (oligomers), we tested their growth-inhibitory effect in SMCs in vitro. Antisense oligomers directed against the translation initiation region of the human c-myc gene exhibited a significant antiproliferative effect, whereas sense and mismatched oligomers did not inhibit the growth. The growth-inhibitory effect of c-myc antisense oligomers was dose dependent and preventable by an excess of sense oligomers. Furthermore, growth inhibition of SMCs treated with c-myc antisense oligomers was associated with a marked decrease in the c-myc mRNA level. Phosphorothioate oligomers remained stable in medium containing 20% serum and were detectable in SMCs as early as 1 hour after cell exposure. Intact oligomers rapidly accumulated intracellularly and persisted within human SMCs for at least 16 hours. CONCLUSIONS: c-myc antisense oligomers reduced c-myc expression and produced a significant growth inhibition of human SMCs, indicating an important role of c-myc gene activation in the process of SMC proliferation. Furthermore, extracellular stability and rapid cellular uptake provide the basis for future studies assessing the therapeutic role of the c-myc antisense approach in reducing SMC proliferation in the process of vascular restenosis.

Cell Division↗

PubMed1993

The Nithsdale schizophrenia surveys. XI: Relatives' expressed emotion. Stability over five years and its relation to relapse.

The level of expressed emotion (EE) in 32 relationships between relatives and schizophrenic patients was assessed on three separate occasions over five years. EE was high on all three occasions in 25% of relatives, low on all three in 38%, and fluctuating in 38%; that is, in the majority of relatives (63%) the level of EE was stable over time. Three relatives who had previously shown high EE had evidence of dementia at the time of the third assessment, and showed low EE. Fourteen patients relapsed at least once over five years; patients who relapsed were evenly spread throughout those living in a home in which EE was consistently high, consistently low, or fluctuating. However, patients living in low-EE homes who did relapse did so significantly less often than those who relapsed and were living in homes in which EE was high or fluctuating. At the time of relapse, EE was not consistently high, and some patients in consistently high-EE homes did not relapse at all over five years.

Adult↗

PubMed1993

Successful conservative management of spontaneous spinal extradural haematoma.

A 69-year-old man developed severe neck and back pain with paraparesis which resolved within 2 h of onset. A CT myelogram demonstrated an extensive anterior extradural haematoma. This and several other cases from the literature suggest that patients with spontaneous spinal haematomas who rapidly recover from their neurological deficit do not require urgent surgical decompression.

Aged↗

PubMed1992

Isolation of a novel cDNA encoding a zinc-finger protein that binds to two sites within the c-myc promoter.

The ME1a1 and ME1a2 elements are cis-acting DNA sequences that exist at positions -46 and -85, respectively, within the P2 promoter of the c-myc gene. These elements are required for optimal transcription initiation from P2. The proteins that bind to these elements are identical or very similar. Here we have isolated a cDNA clone that encodes the carboxy-terminal 494 amino acids of the human ME1a1/ME1a2 factor. This factor is referred to as "ZF87" (zinc-finger protein, 87 kilodaltons). ZF87 specifically binds the ME1a1 element with higher affinity than the ME1a2 element. Western blot analysis indicates that the full-length protein has a relative molecular mass of approximately 87,000 daltons, and Northern blot analysis shows that it is encoded by a 5-kb transcript. ZF87 contains six zinc-finger domains, of the Cys2-His2 type, at the carboxy terminus of the protein. The protein also contains extended tracts of polyalanine.

Amino Acid Sequence↗

PubMed1992

Wild-type murine p53 represses transcription from the murine c-myc promoter in a human glial cell line.

Here we analyzed the effect of the suppressor proto-oncogene p53 on transcription from the P2 promoter of the murine c-myc gene. c-myc promoter constructs were coupled to the chloramphenicol acetyl-transferase (CAT) gene and were transiently transfected into a human glial cell along with plasmids overexpressing wild-type or mutant p53. It was found that significant repression of c-myc transcription took place following cotransfection with wild-type but not mutant p53. However wild-type p53 did not suppress transcription from the SV40 early promoter or from the MHC promoter. Promoter-CAT constructs containing only the ME1a2 or E2F elements, from the P2 promoter, were repressed by p53, indicating that p53 may exert its effect at these two sites within the P2 promoter. Finally, when the SV40 T antigen and wild-type p53 were expressed together in glial cells the repressive effect of p53 was abolished.

Animals↗

PubMed1992

Proteolytic processing of the cardioviral P2 region: primary 2A/2B cleavage in clone-derived precursors.

The primary 2A/2B cleavage within cardiovirus polyprotein was examined by construction of cDNA plasmids which linked fragments from the P2 region of encephalomyocarditis virus (EMCV) and Mengovirus genomes to the EMCV 5' nontranslated region. When RNA transcripts from these clones were tested in reticulocyte extracts, the synthesized proteins were cotranslationally processed at the 2A/2B site. No viral segments outside of the P2 region were required for this activity. Engineered deletions which removed the amino-terminal two-thirds of protein 2A or the carboxyl half of protein 2B had no effect on this scission, nor did insertions into a Ser-Ala-Phe sequence (SAF) within 2B, which is conserved in most cardio- and aphthoviruses. In contrast, mutations which disrupted a conserved Asn-Pro-Gly-Pro (NPGP) sequence abolished primary scission. Precursors thus inactivated were unable to serve as substrate when simultaneously expressed with active (wild-type) 2AB sequences. Microsequencing placed the EMCV primary cleavage site between the Gly/Pro pair within the NPGP sequence. It was also determined that endogenous viral protease 3C is the previously unidentified agent responsible for cardiovirus 1D/2A scission, a cleavage that is part of the primary processing reaction in poliovirus.

Amino Acid Sequence↗

PubMed1992

The Nithsdale schizophrenia surveys. X: Obstetric complications, family history and abnormal movements.

Obstetric histories of 54 schizophrenic patients and 114 siblings were obtained from their mothers and scored using the Obstetric Complications Scale. There were no statistically significant difference in the proportion of schizophrenic patients (35%) and siblings (29%) who had at least one definite obstetric complication. There was no evidence that schizophrenic patients with a history of obstetric complications were less likely to have a first-degree relative with a history of psychiatric illness leading to in-patient care. Schizophrenic patients with a history of obstetric complications were more likely to have drug-induced Parkinsonism. There was a trend for tardive dyskinesia to be more common in those schizophrenic patients with no obstetric complications but a family history of schizophrenia.

Adult↗

PubMed1992

The metabolism of imiloxan hydrochloride in healthy male volunteers.

1. The metabolism of imiloxan hydrochloride [(+-)-2-(1-ethyl-2-imidazoyl)methyl-1,4-benzodioxane hydrochloride], an alpha 2-adrenoceptor antagonist, was studied in four male volunteers given a 500 mg oral dose containing 0.48 MBq of the 14C-labelled material. Compound-related radioactivity was rapidly excreted chiefly in the urine within 24 h of dosing. 2. Metabolites derived by initial oxidation on either or both the benzodioxane and imidazoyl moieties followed by glucuronic acid and sulphate conjugation, and an N-glucuronide of imiloxan were tentatively identified in urine. 3. The major urinary metabolites, comprising some 37-41% of the dose, appeared to be +-2-(1-ethyl-2-imidazoyl)methyl-1,4-benzodioxane-6/7-sulphonic acid (19% of dose), [+-2-(1-ethyl-2-imidazoyl)methyl-1,4-benzodioxane- 6/7-ylium D-glucopyranoside]uronate (10-14% of dose), and a glucuronide conjugate of +-2-(1-ethyl-2-imidazoyl-4/5-hydroxy)methyl-1,4-benzodioxane (8% of dose).

Adrenergic alpha-Antagonists↗

PubMed1992

Three distinct elements within the murine c-myc promoter are required for transcription.

We have undertaken a detailed analysis of the cis-acting elements that are required for optimal transcription initiation from P2, the major promoter of the murine c-myc gene. We find that three elements contribute to promoter strength, termed ME1a2, E2F and ME1a1 at positions -85, -64 and -46 respectively (relative to P2). Individually the elements are weak, but combined they contribute to full promoter activity, all acting in a positive fashion. The E2F element is the site at which the SV40 large T antigen transactivates the c-myc promoter. However, transactivation requires the presence of the ME1a2 or ME1a1 elements in addition to E2F. By a number of criteria it appears that the ME1a2 and ME1a1 elements bind the same or a very closely related protein (monomer Mr 94,000). It was found that Hela cells contain a novel factor that is capable of binding to the ME1a1 and ME1a2 elements but only in the presence of the protein-dissociating agents deoxycholate or formamide. Finally, the E2F factor binds DNA both as a monomer and as a multiprotein complex; the latter is cell type specific. Both types of bound E2F factor form less stable protein-DNA complexes than the ME1a2/ME1a1 factor.

3T3 Cells↗

PubMed1991

Tyrosine phosphorylation of a yeast 40 kDa protein occurs in response to mating pheromone.

Tyrosine phosphorylation of proteins in the yeast Saccharomyces cerevisiae has been examined following exposure to the mating pheromone alpha-factor. When a cells are treated with alpha-factor a protein of approximately 40 kDa molecular weight is tyrosine phosphorylated. This tyrosine phosphorylation response requires an intact signal transduction pathway, is not restricted to a short interval of the cell division cycle, and requires protein synthesis for its maximal accumulation. Mating competent fus3 deletion strains fail to elaborate the phosphotyrosine response. The possibility that FUS3 encodes the 40 kDa protein is discussed.

Blotting, Western↗

PubMed1991

Analysis of the c-myc P2 promoter.

The cis-acting elements governing transcription from the murine c-myc P2 promoter have not been well defined. To gain a better understanding of the nature of the protein-DNA interactions that take place on the P2 promoter, protein binding assays were performed. The ME1a2 and E2F factors appear to be the predominant proteins bound to a region spanning positions -140 to -24 relative to the P2 transcription start site. By a number of criteria, these factors appear to be distinct. When c-myc promoter sequences were coupled to the chloramphenicol acetyltransferase gene (CAT) and transiently transfected into tissue culture cells it was found that optimal transcription from P2 was heavily dependent on the ME1a2 element.

Animals↗

PubMed1991

Anterior plate fixation in spine tumor surgery. Indications, technique, and results.

Anterior decompression by vertebrectomy is now well established as the procedure of choice to optimize neurologic recovery in patients with a deficit due to tumor involvement of the vertebral body. Fifteen patients with tumor involvement of the cervical or thoracic spine and neurologic deficit were treated by single-stage anterior decompression and AO plate stabilization. No patient suffered neurologic deterioration after surgery. All patients with thoracic lesions who were unable to walk on presentation and who managed to survive their primary disease improved to a level that allowed independent ambulation with a frame. There were no problems, such as loss of fixation or deformity. It is concluded that standard AO plates provide adequate stabilization of the cervical and thoracic spine after vertebrectomy for tumor involvement.

Bone Cements↗

PubMed1990

The metabolism of nafimidone hydrochloride in the dog, primates and man.

1. The biotransformation of nafimidone, an imidazole-substituted anticonvulsant, has been studied by characterization of urinary metabolites in dogs, cynomolgus monkeys, baboons and man. 2. The biotransformation of nafimidone in these laboratory animals and man is initially very similar, in each case proceeding by reduction to the aliphatic alcohol metabolite, nafimidone alcohol or 1-[2-hydroxy-2-(2-naphthyl)ethyl]imidazole. 3. Further transformation of this metabolite involves oxidation in the naphthyl and imidazole functions, and/or conjugation. 4. The dog differs from the higher primates in that no metabolic modification of the naphthyl group takes place, the major metabolite in the dog being the O-beta-glucuronide of nafimidone alcohol. 5. In higher primates and man two isomers involving dihydroxylation in the naphthyl ring--1-[2-hydroxy-2-(5,6- or 7,8-dihydroxydihydro-2-naphthyl)ethyl]imidazole--were tentatively identified. These species alone showed evidence of an imidazole linked N-glucuronide of nafimidone alcohol. 6. The possible occurrence of stereoselective metabolism by the introduction of a chiral centre at C-9 in nafimidone alcohol was indicated in human urine by the presence of both epimers of the O-beta-glucuronide of nafimidone alcohol in a 2:1 ratio.

Adult↗

PubMed1990

Regulation of c-myc transcription in vitro: dependence on the guanine-rich promoter element ME1a1.

P2 is the major promoter for the murine c-myc proto-oncogene. The cis-acting elements that are required for initiation of transcription from P2 have not been well defined. In this report elements involved in initiating transcription from P2 were analysed in an in vitro system. In addition to a consensus TATA element at position -28, a guanine-rich element exists at position -48. This element, termed ME1a1, increases transcription initiation when inserted into a deletion mutant that lacks it. When mutations are engineered into ME1a1 it no longer acts to increase the level of initiation. Gel-shift and DNAase I footprinting analysis indicate that Me1a1 binds a protein. ME1a1 does not show any striking similarity to other promoter elements and therefore may be a novel cis-acting element.

Base Sequence↗

PubMed1989

Interleukin-1 is a potent regulator of JE and KC gene expression in quiescent BALB/c fibroblasts.

Interleukin-1 alpha and beta are polypeptide hormones with a broad range of biological activities. Both interleukins are recognized by a receptor that has been characterized as a member of the immunoglobin superfamily. The interleukin-1 receptor does not appear to be a tyrosine protein kinase. Moreover, the intracellular events that mediate the multiple interleukin-1 responses are poorly understood. Here we show that the JE and KC genes, first isolated and characterized as platelet-derived growth factor inducible in quiescent BALB/c-3T3 fibroblasts, are induced by femtomolar concentrations of recombinant interleukin-1 alpha (rIL-1). The response of JE and KC to IL-1 occurs at the transcriptional level. These observations suggest that an analysis of the JE and KC transcriptional response to rIL-1 may aid in identifying elements involved in interleukin-1-mediated signal transduction

Animals↗

PubMed1989

The role of arthroscopy in children and adolescents.

A retrospective review of the first 5 years' experience with arthroscopy at the Adelaide Children's Hospital was conducted. Two hundred and twelve arthroscopies were performed in 192 patients. The average period of follow-up was 5.9 months. The most common arthroscopic finding was anterior cruciate ligament (ACL) injury, followed by meniscal lesions, chondromalacia patellae, patellar dislocations, and osteochondritis dissecans. There was a high rate of associated lesions with ACL tears and acute patellar dislocation. Septic arthritis responded well to arthroscopic drainage and lavage. We concluded that arthroscopy is a safe and accurate diagnostic and therapeutic tool in childhood and adolescence. Arthroscopy is recommended when a joint is too painful to allow adequate clinical examination, in hemarthroses, for ACL injury, after acute patellar dislocation, and to treat septic arthritis. There is only a 56% chance of making a correct diagnosis on clinical grounds, which contrasts with an accuracy in excess of 99% with arthroscopy.

Adolescent↗

PubMed1989

Anterior cruciate ligament injury in children and adolescents.

Although the natural history of anterior cruciate ligament (ACL) injuries in the adult is well documented, the natural history of ACL injury in children and adolescents has not previously been reported. A case note review revealed 31 cases with ACL pathology out of 212 arthroscopies performed in the Adelaide Children's Hospital from November 1980 until June 1986. Partial tears were more common than complete midsubstance tears. In 27 cases there was no bony involvement. All 27 patients were available for analysis. The average age was 14.3 years, with a range of 8-18 years. Twelve of the 27 patients were younger than 14 years old. All patients completed a questionnaire and were interviewed. The average follow-up was 51 months (range 26-87 months). At the time of initial injury, 11 of the 27 patients (41%) had associated pathology. Subsequently, four patients have undergone further arthroscopic surgery, four patients have had a reconstruction of the ACL, and a further three have had reconstruction recommended. We conclude that this is not as benign an injury as was previously believed.

Adolescent↗

PubMed1989

Paraplegia following surgery of the descending thoracic aorta.

Paraplegia remains an uncontrollable complication of aortic reconstructive surgery. Twenty-one consecutive patients undergoing surgery at the Royal Adelaide Hospital for lesions of the descending thoracic aorta were reviewed. Those patients suffering an acute traumatic transection had a much higher rate of postoperative paraplegia (40%) than those undergoing elective reconstruction of chronic aneurysms (10%). The incidence of paraplegia after surgery for an acute transection when bypass was not employed was greater than 50%. In contrast, the outcome was successful in all patients who underwent reconstruction using left heart extracorporeal bypass. Based on these findings, the routine use of bypass during reconstruction of the thoracic aorta is recommended, particularly for acute traumatic transection.

Adult↗