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S N Jones

Publications and source records attributed to S N Jones.

At least 19 recordsLinked to original sources
PubMed1992

Targeting of hexokinase 1 to liver and hepatoma mitochondria.

The proportion of hexokinase (HK; EC 2.7.1.1) isozyme 1 (HK1) that is bound to the outer mitochondrial membrane is tissue specific and developmentally regulated. HK activity is known to be markedly elevated in many cancer cells and a significant fraction is mitochondrial bound. This study examined the role of the 15-amino acid N-terminal domain of HK1 in binding to liver and hepatoma mitochondria. A chimeric reporter construct, pCMVHKCAT, encoding this HK1 domain coupled to the chloramphenicol acetyltransferase (CAT) gene was electroporated into mouse Hepa 1-6 hepatoma cells. After digitonin treatment, cell fractions were assayed for HK, lactate dehydrogenase, and CAT activities. Digitonin (75 micrograms/mg of protein) caused cytosolic leak but 70% of HK remained with the pellet. HKCAT, like HK, remained predominantly with the pellet; CAT form the control, pCMVCAT, remained mostly unbound. Binding of membrane-free cell extracts to rat liver mitochondria in vitro showed 91% of the HKCAT bound, whereas only 12% of CAT bound. Specificity of HKCAT binding to mitochondria was demonstrated by competition of HK1 for HKCAT binding sites on rat liver mitochondria as well as by blockage of HKCAT binding by N,N'-dicyclohexylcarbodiimide, which covalently binds to porin and blocks HK1 binding. Deletional mutant constructs of HKCAT showed reduced binding with increasing deletion size. In summary, these studies demonstrate that the 15-amino acid N-terminal domain of HK1 is necessary and sufficient to confer mitochondrial binding properties to CAT and that there is specificity for this binding to the mitochondria.

Animals↗
PubMed1992

Retroviral-mediated gene transfer of human ornithine transcarbamylase into primary hepatocytes of spf and spf-ash mice.

The sparse fur (spf) and the sparse fur/abnormal skin and hair (spf-ash) mice are two murine models of the human X-linked disorder ornithine transcarbamylase (OTC) deficiency. A defective recombinant retrovirus, delta N2OTC was used to transduce primary hepatocytes derived from these mutant animals. Transduction of the primary cultures was highly efficient, with an average proviral copy number of 0.5-2 per cell in the population of transduced hepatocytes. Northern analysis and slot blots of total RNA isolated from transduced cells showed levels of human OTC mRNA to be equivalent to that present in normal human liver. Enzymatic assays demonstrated that a partial biochemical correction of the defect was achieved. After retroviral transduction, the hepatocytes were trypsinized and replated for long-term culture. Viability after replating exceeded 90%, indicating that the transduced cells might be useful for transplantation. The successful in vitro correction of OTC deficiency by this vector suggests that it will also be useful in somatic gene therapy experiments.

Animals↗
PubMed1992

Functional diversity of E1A gene autoregulation among human adenoviruses.

Autoregulation of the adenovirus E1A gene involves its constitutive expression and positively and negatively regulated transcription. Dissection of this process will identify basal-level cis elements and autoregulatory targets of the E1A promoter and functional domains within the trans-acting E1A gene products. In this report, the DNA sequence of the human subgroup B adenovirus type 3 (Ad3) E1A gene is presented and compared with that of the E1A genes of similar and distantly related human adenoviruses. The cDNA forms of the Ad3 E1A gene, corresponding to two major early mRNA species, are cloned, sequenced, and subcloned into plasmid expression vectors. Cotransfections of cell cultures are performed with Ad5 or Ad3 E1A gene expression plasmids and a reporter gene under control of the Ad5 or Ad3 E1A promoter. The Ad5 and Ad3 E1A promoters are similarly repressed by either serotype's 12S cDNA gene products. The Ad3 E1A promoter responds much more strongly than the Ad5 E1A promoter to transactivation by 13S cDNA gene products. In contrast, the 13S cDNA gene of Ad5 has greater transactivation activity than that of Ad3. Experiments with missense mutations of the Ad5 E1A gene indicate that transactivation of the Ad5 E1A promoter is weak, just reversing or balancing negative autorepression. Single amino acid substitutions in the conserved, repressive functional domain 2 of the E1A gene modulate transactivating activity that is usually associated with the separate and distal conserved functional domain 3. These results suggest a strong structure-function relationship influenced by the variable sequences separating these conserved domains.

Adenovirus Early Proteins↗
PubMed1991

Induction of the Cyp1a-1 dioxin-responsive enhancer in transgenic mice.

Cyp1a-1, whose product, aryl hydrocarbon hydroxylase, assists in detoxification of polycyclic aromatic hydrocarbons, is the best characterized of the murine cytochrome P450 genes. The Cyp1a-1 dioxin-responsive enhancer region has been previously analyzed in vitro and found to induce expression of heterologous genes upon exposure of transfected cells to various aromatic hydrocarbons. A 2.58 kbp DNA fragment containing the Cyp1a-1 enhancer elements and promoter region was coupled to the chloramphenicol acetyltransferase (CAT) reporter gene and used to create transgenic mice. CAT assays were performed on tissues harvested from three different lines of transgenic mice following mock-induction or induction using the aromatic hydrocarbon, 3-methylcholanthrene. Basal levels of expression were detected in the spleen and small bowel of non-induced mice, with little or no expression detected in the liver. Treatment with 3-methylcholanthrene increased hepatic expression levels by as much as 10,000-fold. More modest levels of induction were also recorded in the spleen, small bowel, kidney, and lung. The results indicate that the dioxin-responsive enhancer region functions as a strongly inducible promoter in vivo. Differences in the response to induction between male and female mice suggest that Cyp1a-1 expression may be governed in a gender related manner.

Animals↗
PubMed1991

'Anoddia'.

Explore the source record for details and available documents.

Adult↗
PubMed1990

Ectopic correction of ornithine transcarbamylase deficiency in sparse fur mice.

The sparse fur (spf) mutant mouse is a model for human X-linked ornithine transcarbamylase (OTC) deficiency. Human OTC cDNA placed under transcriptional control of the mouse OTC promoter was microinjected into fertilized oocytes of spf mice. Two founder lines of transgenic mice were phenotypically and biochemically corrected for OTC deficiency by the expression of the human gene at high levels in the small intestine with little or no expression occurring in the liver. The tissue pattern of expression of transgenic mice bearing the chloramphenicol acetyltransferase gene placed under the control of the mouse OTC promoter parallels these results. These experiments demonstrate that human OTC cDNA is selectively expressed in small bowel by a truncated OTC promoter, and such ectopic expression corrects the spf phenotypic and metabolic features of this inborn error. These data suggest that somatic gene therapy of OTC deficiency can be achieved by intestine-targeted gene transfer.

Animals↗
PubMed1989

The interpretation of retrograde pancreatography in the elderly.

Endoscopic retrograde pancreatography is regarded as the most specific technique in the diagnosis of chronic pancreatitis. In the elderly the relevance of endoscopic retrograde pancreatography changes in establishing the diagnosis is disputed. The pancreatograms of 101 patients aged seventy-five years or more, who had endoscopic retrograde pancreatography for suspected biliary or pancreatic pathology, were reviewed. Only four patients subsequently proved to have unequivocal chronic pancreatitis. There was no significant difference in the size or contour of the main pancreatic duct, or in side branch changes between those patients presenting with common bile duct stones, incidental biliary pathology and pain of probable pancreatic origin. Three definite diagnostic criteria for the diagnosis of chronic pancreatitis emerged--duct obstruction with a stricture, gross irregularity of the main pancreatic duct and the presence of large cavities.

Aged↗
PubMed1989

Non-operative management of gallstones--a preliminary review.

We describe our initial experience with extracorporeal shock-wave lithotripsy, direct solvent dissolution with methyl tert-butyl ether and mechanical extraction, in 17 symptomatic patients without significant gall-bladder wall disease using existing criteria for selection. Extracorporeal shock-wave lithotripsy and mechanical extraction are promising techniques. Methyl tert-butyl ether therapy has been fraught with difficulty.

Adult↗
PubMed1989

Fibrin sealant as a plug for the post liver biopsy needle track.

Some patients are at particular risk of haemorrhage after liver biopsy. We describe the use of a two-component fibrin sealant (Tisseel, Immuno) for embolising the track left after biopsy with the 18 gauge 'Biopty' needle. In our series of five cases there have been no bleeding complications. We consider Tisseel much easier to apply than previously described embolisation materials.

Biopsy, Needle↗
PubMed1989

Upstream DNA sequences determine different autoregulatory responses of the adenovirus types 5 and 3 E1A promoters.

Adenovirus types 5 and 3 (Ad5 and Ad3), two human adenovirus serotypes of evolutionarily divergent subgroups, show very different levels of E1A gene expression early after infection of permissive cells. Since adenovirus E1A gene expression is known to be transcriptionally autoregulated, we have investigated the difference between Ad3 and Ad5 by monitoring transient expression of a reporter gene under transcriptional control of the E1A promoter of Ad5 or Ad3. There was only a modest difference between the basal levels of transcription driven by these two E1A promoters. This difference was amplified from 10 to 100 times by the different net responses of the E1A promoters to concomitantly expressed E1A genes. Each promoter had a characteristic net response to positive and negative regulation by E1A gene products. The Ad5 E1A promoter was more strongly repressed, whereas the Ad3 E1A promoter was more strongly activated by E1A gene products. Experiments with a chimeric Ad5/3 E1A promoter indicated that these different autoregulatory responses are determined by DNA sequences which are more than 50 base pairs upstream from the E1A transcriptional start site. A plausible target DNA sequence for positive and negative autoregulation by E1A gene products is discussed.

Adenovirus Early Proteins↗
PubMed1988

Diagnosis and grading of chronic pancreatitis by morphological criteria derived by ultrasound and pancreatography.

The most commonly used modalities in the diagnosis of chronic pancreatitis are ultrasonography, computed tomography (CT) and endoscopic retrograde pancreatography (ERP). Computed tomography scanning is only of value in severe chronic pancreatitis. Both ultrasound and pancreatography are capable of showing ductal changes in mild forms of the disease, but comparison of the two methods has been difficult. A scheme of morphological criteria and descriptive terminology of pancreatitis was applied to 58 out of 85 patients with a firm clinical diagnosis of chronic pancreatitis. Twenty-seven patients were excluded from the study, four with a faulty clinical diagnosis and 23 with non-diagnostic pancreatograms. There was an exact classification into normal, equivocal, mild, moderate or marked chronic pancreatitis in 50 out of 58 patients (86%) and an almost perfect correlation (+ or - one grade) in 54 out of 58 (93%). There were four discrepancies. Ultrasound examination missed focal pancreatitis in the tail, a small cavity in the uncinate process and a variant of chronic pancreatitis. One ultrasound scan was of poor quality. Morphological grading by different techniques is feasible and use of this scheme can reduce diagnosis to a simple and specific set of rules.

Cholangiopancreatography, Endoscopic Retrograde↗
PubMed1986

Autoregulation of adenovirus E1A gene expression.

We examined E1A gene expression by two evolutionarily divergent human adenoviruses, type 5 (subgroup C) and type 3 (subgroup B). Adenovirus type 3 (Ad3)-infected A549 cells contained much larger amounts of E1A-specific RNA than adenovirus type 5 (Ad5)-infected cells, from very early (3 h) through the late stages (20 h) after infection. The appearance of such abundant Ad3 E1A transcripts was delayed after infection of Ad5 E1A-expressing 293 cells, suggesting a down regulation of the Ad3 E1A gene by Ad5 E1A gene products. In a reciprocal manner, coinfection of A549 cells led to typically early and intense Ad3 E1A transcription and strongly inhibited transcription of the Ad5 E1A gene. Transient expression assays were developed so that the autoregulation of the E1A gene could be studied apart from the more complex background of infected cells. The DNA sequence surrounding the transcription start site of the Ad3 E1A gene was placed 5' to the sequence which encodes the bacterial chloramphenicol acetyltransferase gene. Cotransfection of HeLa cells with Ad3 or Ad5 E1A-expression plasmids increased the expression of the Ad3 E1A promoter-driven chloramphenicol acetyltransferase gene. Taken together, these results suggest dual autoregulatory features of adenovirus E1A gene expression. The positive and negative effects appear to be temporally distinguished under different conditions, both in viral infection and in transient assays with plasmid-cloned genes.

Acetyltransferases↗