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Biomedical subjects

M J Hughes

Publications and source records attributed to M J Hughes.

At least 19 recordsLinked to original sources
PubMed2001

Point mutations and overexpression of Ron induce transformation, tumor formation, and metastasis.

The receptor tyrosine kinase Ron is a member of the receptor family that includes the proto-oncogene Met and the avian oncogene Sea. The interaction of Ron with its ligand, known as hepatocyte growth factor-like protein (HGFL) or macrophage stimulating protein (MSP), induces crucial cellular responses including invasive growth, proliferation, cell scattering, and branching morphogenesis. Based on the homology and functional similarities between Met and Ron it was hypothesized that Ron may be important in tumor formation and metastasis. To test this hypothesis, wild-type mouse Ron and three mutant forms of Ron containing mutations similar to those found in the Met gene in human hereditary papillary renal carcinoma (HPRC), were expressed in NIH3T3 cells. A transformed phenotype was produced in cell lines expressing either wild-type Ron or the mutated Ron proteins. Further, these cell lines displayed oncogenic potential by exhibiting increased proliferation and constitutive phosphorylation of Ron. These cell lines were also tested for the ability to form solid tumors. Cells expressing wild-type Ron and the three proteins with single amino acid substitutions were highly tumorigenic in vivo. In a model of experimental metastasis, two of the cell lines with altered Ron protein formed highly aggressive tumors in the lungs. These results suggest that Ron may be an aggressive oncogene when either overexpressed or when activated by mutation.

3T3 Cells↗
PubMed2001

Age-dependent presence of antibodies in rat dams, capable of conferring protection against group B Streptococcus infection in neonates.

A rat model was used to investigate maternal age-dependent resistance on group B Streptococcus (GBS)-induced mortality of the offspring. Offspring from young (first time) or older (repeat litters) dams were challenged with GBS. There was an approximate log difference in the dose of GBS required to cause identical levels of mortality in the two groups. The sera of the dams from both groups were analysed by whole-cell ELISA, and it was demonstrated that sera from the older dams possessed circulating IgG cross-reactive to GBS. Since IgG is transplacentally transferred, we conclude that this is the method of observed protection.

Aging↗
PubMed2000

Treatment of iatrogenic femoral artery pseudoaneurysms using ultrasound-guided injection of thrombin.

AIM: To evaluate the use of ultrasound-guided percutaneous injection of thrombin for treatment of femoral artery pseudoaneurysms. METHOD: Nine patients with a confirmed femoral false aneurysm were included in the study. 0.5-1 ml of a 2000 U/ml solution of activated bovine thrombin was injected under ultrasound visualization into the neck of the aneurysm to induce thrombosis. The parent artery and adjacent major vessels were checked during and after the procedure to exclude propagation of thrombus. A check ultrasound examination was undertaken on the following day. RESULTS: Eight patients were successfully treated by a single injection. One patient required a second injection due to recurrence of their pseudoaneurysm 4 days after the initial treatment. The procedure was well tolerated in all cases and no complications were encountered. CONCLUSION: This small series provides further evidence that ultrasound-guided thrombin injection is a promising new method for the treatment of femoral false aneurysms.Hughes, M. J. et al. (2000). Clinical Radiology55, 749-751.

Aneurysm, False↗
PubMed1999

cDNA isolation, genomic structure, regulation, and chromosomal localization of human lung Kruppel-like factor.

Lung Kruppel-like factor (LKLF) is a zinc finger transcription factor critical for embryonic development. We have previously identified and isolated the mouse LKLF gene and examined its role using gene targeting. In this report, we describe the isolation and molecular characterization of the human homolog of murine LKLF. The human and mouse LKLF homologs exhibit an 85% nucleotide identity and share 90% amino acid similarity. Furthermore, the 5' sequence in the proximal promoter region and 3' untranslated region are also conserved between the two species. Of particular interest is the finding that while sequences in the proximal promoter have diverged between mouse and human, a region of 75 nucleotides is essentially identical. Site-directed mutagenesis in this region impairs the ability of the LKLF promoter to drive reporter gene expression, indicating that it represents a novel transcriptional element important in the regulation of LKLF gene expression. The activation domain is highly proline-rich and, similar to mouse LKLF, contains 22% proline residues. The human LKLF transcriptional unit is located in a genomic region of approximately 3 kb on chromosome 19p13.1. This region of chromosome 19 is known to contain genes involved in various human diseases. Like mouse LKLF, human LKLF consists of three exons that are interrupted by two small introns. The locations of intron/exon boundaries and splice sites are conserved between two homologs. Northern analysis shows that LKLF is expressed in lung in addition to heart, skeletal muscle, placenta, and pancreas. The isolation and chromosomal mapping of human LKLF will make it possible to initiate studies devoted to assess the involvement of this gene in human disease(s).

Amino Acid Sequence↗
PubMed1999

Characterization of the lung Krüppel-like transcription factor gene and upstream regulatory elements.

We previously described the isolation and characterization of the cDNA for lung Krüppel-like factor (LKLF), a zinc finger transcription factor that is predominately expressed in the lung of adult mice. In this study, we report the complete structure and nucleotide sequence of the mouse LKLF gene, which is comprised of three exons and two small introns. Moreover, the identification of critical sequence elements required for expression is described using reporter constructs with the LKLF promoter transfected into LA-4 lung cells. Results from these constructs reveal an important region for transcriptional activity that lies between the -490/-72bp upstream sequence. This region contains two canonical Sp1 binding sites that affect expression levels in a non tissue-specific manner. In addition, using a base-pair mutagenesis strategy, a region from -157/-72bp was found to be necessary for upregulating expression. In transfection assays, mutations of the -138/-111bp region resulted in approximately 70-80% loss of promoter activity. This cis-element does not appear to correspond to any known transcription factor consensus sequence. Moreover, mutations within this cis-region disrupt the binding of a protein complex from nuclear extracts of various tissues.

Animals↗
PubMed1999

Surviving OR construction projects from conception to completion.

Suppose an OR needs a new floor, new sterilizers, a new ventilation system, overhead lights, or a floor-to-ceiling renovation. How can an OR manager or director manage a project of this magnitude and continue to provide safe, effective, and efficient patient care? This article explains how, with proper planning, construction projects can be managed safely, effectively, and efficiently for patients, staff members, physicians, and contractors.

Communication↗
PubMed1999

Method of preparing emergency medicine residents for giving legal depositions.

This study was performed to determine if a simulated legal deposition increases emergency medicine (EM) residents' knowledge, self-confidence, and understanding of a legal deposition. This prospective study included a convenience sample of EM 1-3 residents. A knowledge and a self-assessment pretest were given, followed by a didactic session moderated by local attorneys, followed by knowledge and a self-assessment posttest. The total time involved was 2 hours. The mean score on the knowledge pretest was 4.5 and 5.25 on the posttest. Using a paired t-test, the authors found this difference to be statistically significant. (P < 0.01) Using Hotelling's T2 test, the authors compared presimulation and postsimulation self-assessment questions. The results revealed that there was a difference between these scores (P < 0.001). Participants in the deposition significantly improved their self-assessment ranking and knowledge inventory test scores by participating in a simulated legal deposition.

Adult↗
PubMed1998

Characterization of tomato PHYB1 and identification of molecular defects in four mutant alleles.

The structure of the gene encoding the apoprotein of phytochrome B (PHYB1) in tomato has been determined from genomic and cDNA sequences. In contrast to PHYA, PHYB1 lacks an intron upstream of the first ATG. A single transcription start site was found by 5' RACE at -116. Tomato PHYB1 spans 7 kb starting from the first ATG. The coding region is organized into four exons as for other angiosperm PHY. The deduced apoprotein consists of 1131 amino acids, with a molecular mass of 125.4 kDa. Tomato phytochrome B1 shares 78% and 74% identity with Arabidopsis phytochromes B and D, respectively. Along with the normally spliced full-length transcripts, sequences of reverse transcriptase-PCR clones revealed five types of alternative transcripts. Each type of alternative transcript was missing a considerable part of the coding region, including the chromophore-binding site. The four putative PHYB1 mutants in tomato, which are temporarily red-light insensitive (tri), were each confirmed to have a mutation in PHYB1. Each mutation arose from a different, single-base substitution. Allele tri1 is presumably a null because the mutation introduces a stop at codon 92. In tri3, val-238 is replaced by Phe. The importance of this valine residue is evidenced by the fact that the tri3 phenotype is as strong as that of tri1. Alleles tri2 and tri4 encode proteins truncated at their C-termini. The former lacks either 170 or 438 amino acids, depending upon which of two types of splicing occurs during transcript maturation, while the latter lacks 225.

Alleles↗
PubMed1998

Interstitial cells of Cajal generate a rhythmic pacemaker current.

Networks of interstitial cells of Cajal embedded in the musculature of the gastrointestinal tract are involved in the generation of electrical pacemaker activity for gastrointestinal motility. This pacemaker activity manifests itself as rhythmic slow waves in membrane potential, and controls the frequency and propagation characteristics of gut contractile activity. Mice that lack a functional Kit receptor fail to develop the network of interstitial cells of Cajal associated with Auerbach's plexus in the mouse small intestine and do not generate slow wave activity. These cells could provide an essential component of slow wave activity (for example, a biochemical trigger that would be transferred to smooth muscle cells), or provide an actual pacemaker current that could initiate slow waves. Here we provide direct evidence that a single cell, identified as an interstitial cell of Cajal by light microscopy, electron microscopy and expression of Kit mRNA, generates spontaneous contractions and a rhythmic inward current that is insensitive to L-type calcium channel blockers. Identification of the pacemaker of gut motility will aid in the elucidation of the pathophysiology of intestinal motor disorders, and provide a target cell for pharmacological treatment.

Animals↗
PubMed1997

A single nucleotide is a sufficient 5' untranslated region for translation in an eukaryotic in vitro system.

The 5' untranslated region of an RNA molecule is thought to play an important role in the regulation of translation. Following a recent report that a single nucleotide is sufficient to act in this role in the unicellular organism Giardia, we show that this is also the case for a mammalian in vitro system. These results also demonstrate that an RNA can initiate translation from a start codon where an ideal translational consensus sequence is impossible.

Amino Acid Sequence↗
PubMed1996

Non-histone protein 1 (NHP1) is a member of the Ku protein family which is upregulated in differentiating mouse myoblasts and human promyelocytes.

We have previously purified and characterized a ubiquitous non-histone protein (NHP1) which has a high affinity (Kd 10(-11) M) for different avian vitellogenin gene sequences containing CpGs (Hughes et al. (1989) Biochemistry 28, 9137-9142; Hughes and Jost (1989) Nucleic Acids Res. 17, 8511-8520). Here we show by microsequencing that the peptides derived from the purified p75 and p85 subunits of NHP1 from HeLa cells have between 64 and 100% identity with the human Ku autoantigen. During the differentiation of human HL-60 promyelocytes there is an increase in the amount of p85 subunit protein whereas the level of the p75 subunit is unchanged. In differentiating mouse G8 myoblasts there is, however, an upregulation of both the p75 and p85 subunits and of the p85 mRNA. An inhibition of mouse myoblast differentiation by either cAMP, 3-aminobenzamide or sodium butyrate abolishes the upregulation of the p85 subunit. In G8 myoblasts chemical, or physical stress by UV light or X-rays does not upregulate the level of the p85 subunit. The possible involvement of NHP1 in the active demethylation of bifilarly methylated DNA will be discussed.

Amino Acid Sequence↗
PubMed1996

A pilot study of combination therapy with interferon-alpha-2a and 5-fluorouracil in metastatic carcinoid and malignant endocrine pancreatic tumours.

BACKGROUND: In view of the encouraging single agent response rates to interferon and 5-fluorouracil (5-FU) in malignant carcinoid and endocrine pancreatic tumours and the theoretical benefits of combination therapy with 5-FU and interferon in other tumours a study was designed to look at the feasibility of this combination, given for 12 months, in these tumours. PATIENTS AND METHODS: Patients were treated with 5-FU 750 mg/m2 by intravenous bolus every week and 3 Mega Units of recombinant interferon-alpha-2a subcutaneously 3 times per week increasing, as tolerated, to 6 then 9 MU. Fifteen patients were entered into the study. RESULTS: One patient died suddenly of an unrelated illness and is not assessed. None of the remaining 14 patients had radiological evidence of response to treatment, although 6 had stable disease lasting for 7 to 64 weeks (median 40 weeks). Two patients did have biochemical evidence of a response, i.e., a 50% reduction in baseline urinary 5HIAA for 26 and 52 weeks. Treatment toxicity was significant. Six patients stopped treatment prematurely because of either nausea and/or diarrhoea. Overall treatment duration ranged from 4 to 64 weeks (median 7.5 weeks). CONCLUSION: Overall we found the treatment to be disappointing in terms of tolerance and response rate and do not recommend its use in malignant carcinoid or endocrine pancreatic tumours.

Adult↗
PubMed1995

The 3' untranslated region of bovine preprolactin contains a transferable non-poly(A) mRNA sequence that prolongs translation.

Preprolactin transcripts, synthesized in vitro, were actively translated for a prolonged period when injected into Xenopus oocytes. As a result, prolactin continued to be secreted into the media for up to 6 days after injection of the transcript. To investigate the role of the preprolactin 3' untranslated sequence in stabilizing transcripts, it was fused to coding regions derived from signal recognition particle receptor alpha-subunit or preproinsulin receptor. The translational half-life of the chimeric RNA was increased for both coding regions, suggesting that a sequence within the preprolactin 3' untranslated region that prolongs translation is transferable. Deletion mutagenesis of this untranslated region demonstrated that a sequence of 98 nucleotides immediately following the prolactin stop codon was sufficient to prolong translation of RNAs injected into Xenopus oocytes.

Animals↗
PubMed1995

Comparison of tetracaine-adrenaline-cocaine (TAC) with topical lidocaine-epinephrine (TLE): efficacy and cost.

Topical anesthesia in the form of TAC (tetracaine, adrenaline, cocaine) solution has been used for wound repair. This pilot study was designed to determine if the topical anesthesia achieved using a mixture of lidocaine (5%) and epinephrine (1:2000) (TLE) is equivalent to the topical anesthesia obtained using a solution of tetracaine (0.5%), epinephrine (1: 2000), and cocaine (10.4%) (TAC). A prospective, randomized, double-blind trial was carried out from May 1992 to August 1992 at a community-based teaching hospital Emergency Department (ED) that receives 50,000 annual visits. Patients with facial or scalp lacerations suitable for topical anesthesia presenting to the ED were included when study physicians were in attendance. Exclusion criteria included the presence of a sensory altering substance (eg, ethanol), age younger than two years, hypertension, pregnancy, allergy to any of the study's pharmacological agents, wounds greater than six hours old, grossly contaminated wounds, and wounds longer than six centimeters. Either a TAC or TLE solution was applied to lacerations before suturing. The laceration was repaired and the patient or physician evaluated the degree of pain from the procedure by using a standardized visual pain scale. A total of 35 patients were studied. Seventeen patients were in the TLE group; 18 in the TAC group. The mean ages were compared and found to be similar (P = .40) between the two test groups. The pain scale values, the diameter of tissue blanch around laceration (halo size), and the time to laceration repair from the onset of application of anesthetic were compared and no difference was shown between the TAC and TLE groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗