Biomedical subjects

L E Wilson

Publications and source records attributed to L E Wilson.

At least 19 recordsLinked to original sources

PubMed2001

Dynamics of SEN virus infection among injection drug users.

SEN virus (SENV) is a recently discovered group of DNA viruses whose members (SENV-D and SENV-H) are linked to posttransfusion hepatitis. Of 397 injection drug users (IDUs) in Baltimore, Maryland, SENV-D infection was detected by polymerase chain reaction in serum samples from 130 (32.7%) and SENV-H infection in 149 (37.5%). Of 41 IDUs in whom SENV-D DNA was initially detected, retesting for viral persistence a median of 9.3 years later detected SENV-D in 25 (61.0%), whereas SENV-H was detected on retesting in only 14 (26.9%) of 52 IDUs in whom the virus was originally found. Reinfection was apparent (>5% nucleotide difference) in 77.8% of IDUs who repeatedly tested positive for SENV-D DNA and in 55.6% of those who repeatedly tested positive for SENV-H DNA. Among Baltimore IDUs, SENV-D and SENV-H infections are common and dynamic, including both viral clearance and reinfection. The clinical significance of SENV infection in this setting remains unknown.

Adult↗

PubMed2000

HTLV-II and bacterial infections among injection drug users.

OBJECTIVE: To examine whether select bacterial infections are associated with HTLV-II infection among injection drug users, we conducted a nested case control study within an ongoing cohort study. METHOD: HTLV-II status was determined by enzyme-linked immunosorbent assay, immunofluorescent assay, and immunoblot. Diagnosis of bacterial pneumonia, infective endocarditis, and skin abscess was confirmed by standardized chart reviews. Three sets of cases were identified based on diagnosis of bacterial pneumonia, infective endocarditis validated by chart review, or self-reported skin abscess. Each case was matched to a minimum of 5 controls by age, HIV status, and study follow-up duration. Risk factors for each bacterial infection were analyzed separately by conditional logistic regression methods. RESULTS: Prevalence of HTLV-II infection ranged from 7% to 11% in cases and controls. The bivariate association of HTLV-II and bacterial pneumonia revealed an odds ratio (OR) of 1.1 (95% confidence interval [CI], 0.6-2.0); the association of infective endocarditis and HTLV-II revealed an OR of 1.7 (95% CI, 0. 7-3.9); and the association between HTLV-II and skin abscess revealed an OR of 1.3 (95% CI, 0.6-2.0). These ORs were unaltered by adjustment for other factors. CONCLUSION: Our results suggest that these three bacterial infections were not significantly associated with HTLV-II infection within a population of injection drug users. Additional associations between HTLV-II infection and disease outcomes merit further exploration.

Abscess↗

PubMed2000

The natural history of hepatitis C virus infection: host, viral, and environmental factors.

CONTEXT: Hepatitis C virus (HCV) infection may resolve (viral clearance), persist without complications, or cause end-stage liver disease (ESLD). The frequency and determinants of these outcomes are poorly understood. OBJECTIVE: To assess the incidence and determinants of viral clearance and ESLD among persons who acquired HCV infection from injection drug use. DESIGN AND SETTING: Community-based prospective cohort study with enrollment in 1988-1989 and a median follow-up of 8.8 years. SUBJECTS: A total of 1667 persons aged 17 years or older with a history of injection drug use and an HCV antibody-positive test result during follow-up. MAIN OUTCOME MEASURES: Viral clearance was assessed in a subset of 919 patients and defined as failure to detect HCV RNA in at least 2 consecutive samples collected 5 or more months apart. End-stage liver disease was assessed at semiannual visits and by review of medical records and death certificates and defined by the presence of ascites, esophageal varices, or hepatic encephalopathy, or when ESLD was stated as a cause of death. RESULTS: Viral clearance was observed in 90 persons who were compared with 722 with persistent viremia, while the viremia of 107 was not resolved. Viral clearance occurred more often in nonblacks (adjusted odds ratio [OR], 5.15; 95% confidence interval [CI], 2.60-10.17) and those not infected with human immunodeficiency virus (HIV) (adjusted OR, 2.19; 95% CI, 1.26-3.47). Forty cases of ESLD were observed throughout follow-up (incidence, 3.1 per 1000 person-years). In a multivariate model, risk of ESLD was higher for persons aged 38 years or older at enrollment (adjusted relative incidence, 3.67; 95% CI, 1.96-6.88) and who reported ingestion of more than 260 g of alcohol per week (adjusted relative incidence, 3.60; 95% CI, 1.73-7.52). Of 210 patients without ESLD randomly selected for biopsy, only 2 had cirrhosis. CONCLUSIONS: Our results indicate that although HCV infection can be self-limited or associated with ESLD, the majority of adults have persistent viremia without clinically demonstrable liver disease. Further research is needed to explain the less frequent clearance of HCV infection among black persons and to improve utilization of treatment for those infected in the context of injection drug use. JAMA. 2000;284:450-456

Adult↗

PubMed2000

Dose-response relationship for radiation-induced mutations at micro- and minisatellite loci in human somatic cells in culture.

PURPOSE: The study was designed to determine the dose-response relationship for radiation induction of mutations at mini- and microsatellite loci in human somatic cells. Mutations induced by graded doses of gamma-irradiation were quantified by screening clones derived from single irradiated cells for micro- and minisatellite alterations following irradiation with 1, 2 or 3 Gy. MATERIALS AND METHODS: After irradiation, the moderately radioresistant glioma cell line UVW was seeded at low density into Petri dishes to allow formation of discrete colonies, 100 of which were examined at each dose. All the cells within a colony were presumed to have arisen from a single irradiated cell. Radiation-induced microsatellite alterations were determined at 16 different loci, by PCR amplification and visualization on polyacrylamide gels. Minisatellite alterations were identified at four different minisatellite loci by restriction enzyme digestion and Southern blotting. RESULTS: A dose-response curve for mutation frequency was obtained by analysis of 100 clones, yielding a minisatellite mutation rate of 5.5x10(-3) mutations/locus/Gy/cell and a microsatellite mutation rate of 8.75x10(-4) mutations/locus/ Gy/cell. At microsatellite loci, alterations were predominantly simple loss or gain of repeat units and loss of heterozygosity (LOH). The mutations in minisatellite loci resulted predominantly in LOH and variation in repeat number. The background instability at each locus was determined by analysis of non-irradiated clones. Only 2% and 1% of the micro-and minisatellite loci respectively showed altered bands. CONCLUSIONS: This is the first report of a dose-response relationship for radiation-induced micro- and minisatellite mutations in human somatic cells. Described is a sensitive method for analysis of low-dose radiation mutagenesis in somatic cells that may prove to be a useful tool for radiation protection and dosimetry.

Dose-Response Relationship, Radiation↗

PubMed2000

Expression of the green fluorescent protein carried by Autographa californica multiple nucleopolyhedrovirus in insect cell lines.

A recombinant AcMNPV containing the green fluorescent protein (gfp) gene under the polyhedrin promoter (polh) was used to investigate the expression of the gfp gene as well as the production of recombinant extracellular virus in 14 continuous insect cell lines, including Heliothis virescens (BCIRL-HV-AM1), Helicoverpa zea (BCIRL-HZ-AM1), Anticarsia gemmatalis (BCIRL-AG-AM1), Trichoplusia ni (TN-CL1), Spodoptera frugiperda (IPLB-SF21), Spodoptera exigua (BCIRL/AMCY-Se-E1 and BCIRL/AMCY-Se-E5), Bombyx mori (BMN), Sf9 (a clone of IPLB-SF21), and five cell line clones of BCIRL-HV-AM1. The susceptibility of the cell lines to the recombinant virus (AcMNPV.GFP) was ascertained by calculating the mean percentage number of green light-emitting cells as well as by TCID50 titration of extracellular virus with fluorescence as a sign of infection. Of the 14 cell lines tested, all were permissive with varying degrees to AcMNPV.GFP, except BCIRL-HV-AMCL2 and BCIRL-HZ-AM1, both grown in serum-containing medium, and BMN, grown in serum-free medium, which were nonpermissive to the virus. Except for BCIRL/AMCY-Se-E1, IPLB-SF21, and four of the five BCIRL-HV-AM1 clones, all the other cell lines (BCIRL-HV-AM1, BCIRL-AG-AM1, TN-CL1, Se-E5, and Sf9) expressed detectable levels of GFP by 48 h postinoculation. The BCIRL/AMCY-Se-E1 and IPLB-SF21 cells, grown in serum-free medium (Ex-Cell 401), expressed detectable levels of GFP at 72 h postinoculation. By contrast, in BCIRL/AMCY-Se-E1 in serum-containing medium (Ex-Cell 401 + 10% FBS [fetal bovine serum]), GFP was detected at 48 h postinoculation. Furthermore, TN-CL1 cells produced the largest mean percentage number of fluorescent (76.6%) cells in both serum-containing and serum-free medium (64.8%) at 120 h postinoculation. All the BCIRL-HV-AM1 clones showed no GFP expression until 96 h postinoculation, and only then about 1% of the cell population fluoresced. The mean extracellular virus (ECV) production at 120 h postinoculation was highest in BCIRL/AMCY-Se-E5 cells grown in Ex-Cell 401 + 10% FBS (37.8 x 10% TCID50/ml) followed by BCIRL-HV-AM1 in TC199-MK (33.4 x 10(6) TCID50/ml). Only the BCIRL-HV-AMCL3 clone produced any substantial level of ECV at 120 h postinoculation (16.9 x 10(6) TCID50/ml). However, there was no significant correlation between ECV production and the mean percentage number of fluorescent cells. This study provides further information on the susceptibility of 14 insect cell lines to a recombinant AcMNPV containing the green fluorescent protein gene. This information might avail researchers with information to facilitate decisions as to what other cell lines are available for in vitro studies of the gfp gene.

Animals↗

PubMed1999

Early therapeutic experience with the endothelin antagonist BQ-123 in pulmonary hypertension after congenital heart surgery.

OBJECTIVE: To assess the effect of endothelin type A (ET(A)) receptor antagonism in infants with pulmonary hypertension following corrective surgery for congenital heart disease. DESIGN: Open label, preliminary study. SETTING: Tertiary paediatric cardiothoracic surgical centre. PATIENTS: Three infants (aged 3 weeks, 7 weeks, and 8 months) with postoperative pulmonary hypertension unresponsive to conventional treatment, including inhaled nitric oxide. INTERVENTIONS: Patients received incremental intravenous infusions (0.1 to 0.3 mg/kg/h) of the ET(A) receptor antagonist BQ-123. MAIN OUTCOME MEASURES: The response to BQ-123 administration was determined using continuous invasive monitoring of cardiorespiratory variables. RESULTS: BQ-123 infusion caused a reduction in the ratio of pulmonary to systemic pressures (0.62 (0.01) to 0.52 (0.03), mean (SEM)) with an accompanying decrease in right ventricular stroke work index (4.6 (0.4) to 2.5 (0.3) g/m) and a tendency for the cardiac index to rise (2.1 (0.2) to 2.7 (0.6) l/min/kg/m(2)). This was associated with a well tolerated fall in the arterial partial pressure of oxygen (16.5 (4.1) to 12.4 (3.3) kPa) and mean systemic arterial pressure (57 (3) to 39 (3) mm Hg). CONCLUSIONS: ET(A) receptor antagonism in infants with postoperative pulmonary hypertension after corrective surgery for congenital heart disease led to significant improvement in pulmonary haemodynamic indices. However, these benefits were associated with reductions in systemic blood pressure and arterial oxygen saturation, the latter consistent with a ventilation-perfusion mismatch. On the basis of these results, studies in pulmonary hypertension will need to proceed with caution.

Endothelin Receptor Antagonists↗

PubMed1998

Heartburn requiring frequent antacid use may indicate significant illness.

BACKGROUND: Many otherwise healthy individuals with episodic heartburn self-medicate with over-the-counter antacids. We evaluated clinical characteristics of subjects who had never been medically diagnosed as having any upper gastrointestinal tract disorder and who used antacids for symptomatic relief of heartburn. SUBJECTS AND METHODS: Subjects with at least 3 months of frequent heartburn relieved by antacids, and with heartburn on at least 4 of 7 days during the week prior to study entry, had their medical history and gastrointestinal pathological characteristics recorded. Tests included esophagogastroduodenoscopy, esophageal motility and sensitivity studies, and 24-hour pH monitoring. RESULTS: Of 178 subjects screened, 13 were excluded on the basis of other gastrointestinal diseases at baseline, including diffuse esophageal spasm, peptic ulcer disease, dysplastic columnar metaplasia of the esophagus (Barrett's esophagus), and adenocarcinoma. Ten subjects were ineligible because of insufficient baseline heartburn. The remaining 155 eligible subjects had heartburn for an average of 11 years. Forty-seven percent had daily symptoms and 70% described heartburn severity as moderate, even though on endoscopy most (53%) had normal-appearing esophageal mucosa (grade 0 or 1). Esophageal acid sensitivity was present in 86% of subjects. Mean lower esophageal sphincter pressures and esophageal contractile amplitudes were at the lower limits of normal and total esophageal acid contact time was slightly increased. CONCLUSIONS: Chronic heartburn can reflect a wide range of diagnostic findings, including important underlying pathological features, and may warrant a full medical examination to detect such abnormal conditions and to permit selection of appropriate therapy.

Adenocarcinoma↗

PubMed1998

Assembly of Amsacta moorei entomopoxvirus spheroidin into spheroids following synthesis in insect cells using a baculovirus vector.

The gene encoding the major occlusion body protein, spheroidin, of Amsacta moorei entomopoxvirus (AmEPV) was introduced into a baculovirus vector under control of the polyhedrin gene promoter. A recombinant virus produced large, ovoid occlusion body-like structures in both Spodoptera frugiperda and Trichoplusia ni cells. These structures resembled the spheroids found in AmEPV-infected Lymantria dispar cells, except they were devoid of virus particles and were not surrounded by a membrane- or envelope-like structure. These results were confirmed by immunofluoresence microscopy and Western blotting using a specific antipeptide antibody to spheroidin, and suggest that the supramolecular assembly of spheroids is not dependent on other EPV-encoded gene products. Transmission electron microscopy and subcellular fractionation experiments revealed that the spheroid-like structures were assembled in both the nucleus and cytoplasm of the recombinant virus-infected cells. This contrasts with the solely cytoplasmic localization found in AmEPV-infected cells.

Animals↗

PubMed1997

Identification of recombinant baculoviruses using green fluorescent protein as a selectable marker.

A rapid procedure for the production and identification of recombinant baculoviruses is described that uses the autofluorescent properties of the Aquorea victoria green fluorescent protein (GFP). Expression of the GFP cDNA (without signal peptide sequence) in Spodoptera frugiperda cells resulted in the synthesis of a 30-kDa protein, which was confirmed as GFP by Western blotting and by the emission of green fluorescence when illuminated with longwave UV light (495 or 365 nm). To use GFP as a marker for the selection of recombinant baculoviruses, we prepared a virus, BacGFP1, in which the GFP cDNA was inserted in lieu of lacZ in BacPAK6. Before the use of BacPAK6 or BacGFP1 in a cotransfection to prepare recombinant baculoviruses, the virus DNA was linearized with Bsu361 to improve the recovery of non-parental virus plaques. The use of BacGFP1 DNA resulted in the recovery of 79%-91% plaques with the non-parental phenotype. Plaques were rapidly identified by simply exposing them briefly to longwave UV light (365 nm) without the need for exogenous substrates or biological stains.

Animals↗

PubMed1996

Hypothyroidism alters diaphragm muscle development.

The impact of hypothyroidism (Hyp) on myosin heavy chain (MHC) isoform expression, maximum specific force (P0), fatigability, and maximum unloaded shortening velocity (V0) was determined in the rat diaphragm muscle (Dia) at 0, 7, 14, 21, and 28 days of age. Hyp was induced by treating pregnant rats with 6-n-propyl-2-thiouracil (0.05% in drinking water) beginning at gestational day 10 and was confirmed by reduced plasma levels of 3,5,3'-triiodothyronine and thyroxine. MHC isoforms were separated on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels and analyzed by densitometry. Isometric P0 and fatigue resistance of the Dia were measured in vitro at 26 degrees C, and V0 was determined at 15 degrees C with the slack test. Compared with control muscles, expression of MHC-slow was higher and expression of adult fast MHC isoforms was lower in Hyp Dia at all ages. The neonatal isoform of MHC continued to be expressed in the Hyp Dia until day 28. At each age, P0 and fatigability were reduced and V0 was slower in the Hyp Dia. We conclude that Hyp-induced alterations in MHC isoform expression do not fully predict the changes in Dia contractile properties.

Aging↗

PubMed1995

Genetic modification of an entomopoxvirus: deletion of the spheroidin gene does not affect virus replication in vitro.

In the late stages of an entomopoxvirus infection, virions become embedded within a crystalline occlusion body or spheroid. Spheroids are composed primarily of a single polypeptide, spheroidin. We describe the construction of a genetically modified Amsacta moorei entomopoxvirus (AmEPV) in which the spheroidin gene coding sequences are deleted and replaced with those of a heterologous reporter gene encoding chloramphenicol acetyltransferase (CAT). A transfer vector, pAmCP1, was prepared containing a unique BamHI site in lieu of the spheroidin gene coding region, together with 1 kbp of upstream and downstream DNA sequence that flanks the spheroidin gene. The flanking sequences provide the transcriptional control signals and also guide homologous recombination so that the spheroidin gene coding region can be replaced with that of the foreign gene. The transfer vector was designed so that the translational start codon of the introduced foreign gene would be utilized. A recombinant virus, AmEPV.CAT, was produced by transfecting AmEPV-infected cells with the transfer vector encoding the CAT gene. The recombinant virus was isolated from wild-type virus by identifying plaques with a spheroidin-negative phenotype. Light microscopy and SDS-PAGE analysis demonstrated that no spheroids or spheroidin protein were produced in the recombinant virus-infected cells. The recombinant virus was able to replicate to high titres (10(7) p.f.u./ml) in insect cells indicating that the spheroidin gene is non-essential for AmEPV replication in vitro. Moderate levels of CAT were synthesized in recombinant virus-infected cells and temporal analyses indicated that CAT synthesis followed the pattern of spheroidin production suggesting that the spheroidin gene promoter was functioning under normal regulatory control in the genetically modified virus.

Base Sequence↗

PubMed1994

Contraceptive outcomes among post-partum and post-abortal adolescents.

Between January 1992 and January 1993, there were 280 teens (ages 13-18) who either delivered a baby or terminated a pregnancy at Johns Hopkins Bayview Medical Center. Of these, 92 chose to contracept with Norplant implants, and 188 chose another method including "no" method. In July 1993, telephone interviews were conducted with 37 of those who chose Norplant implants and 41 of the non-Norplant implants users. After 1 year, 47% of oral contraceptive (COC) users had discontinued the method compared to only 16% of Norplant implants users (P < 0.03). Reasons for discontinuation centered on side effects for both groups but with some COC and condom users, discontinuing use due to "forgetfulness" or failure (pregnancy). Among the COC group (which was the most common choice after Norplant implant), 25% of the adolescents had experienced a subsequent unplanned pregnancy compared to 0% of the Norplant implant group (P < 0.01). Norplant implants were clearly an acceptable and effective contraceptive for these post-partum and post-abortal teens, who articulated a high motivation to avoid a subsequent unplanned pregnancy. However, it is clearly not the only method teens will choose to use, and more attention must be paid to adequate counseling of those choosing another method.

Abortion, Induced↗

PubMed1994

Contractile properties of the developing diaphragm correlate with myosin heavy chain phenotype.

The objective of this study was to determine the relationship between developmental transitions in myosin heavy chain (MHC) composition and changes in maximum unloaded shortening velocity (Vo) and maximum specific force (Po) of the rat diaphragm muscle. The diaphragm was excised at postnatal days 0, 3, 7, 14, 21, and 28 and in adults. MHC isoform expression was determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and laser densitometry. In muscle fiber bundles, Vo was determined at 15 degrees C by use of the "slack" test. Isometric Po was determined at 15 and 26 degrees C. Simple and stepwise regressions were used to evaluate the correlations between Vo, Po, and MHC phenotype transitions and the various developmental ages. The progressive increases in Vo and Po with age were found to be inversely correlated to MHC-neonatal isoform expression (r2 = -0.84 and -0.63, respectively) and positively correlated to MHC-2X (r2 = 0.78 and 0.57) and MHC-2B (r2 = 0.51 and 0.40) isoform expression (P < 0.001). Changes in MHC-neonatal isoform expression contributed to most of the developmental variance in Vo and Po, with changes in MHC-2X and MHC-2B expression also contributing significant increments to total variance. The postnatal increase in Vo most likely relates to differences in the actomyosin adenosinetriphosphatase activity between neonatal and adult fast MHC phenotypes. The increase in Po may reflect inherent differences in myofibrillar density, cross-bridge cycling kinetics, and/or the force produced per cross bridge among fibers composed of the different MHC isoforms.

Aging↗

PubMed1993

A long-term follow-up study of children with supracondylar fractures of the humerus.

A retrospective study to assess the long-term results of the treatment of supracondylar fractures of the humerus was undertaken to provide guidance on the management of these troublesome injuries. In our experience as long as there was less than 25% displacement on an anteroposterior (A/P) or lateral x-ray, and less than 10 degrees angulation on an A/P or lateral x-ray, it is not essential to achieve an anatomical reduction, and good elbow function could be expected. Although children do not appear to correct for valgus or varus deformity there was no functional deficit from this deformity in this series. It was found that major displacements were more likely to have a worse result than undisplaced or minimally displaced fractures. These results would support a conservative approach to the management of these fractures--closed reduction followed by three weeks in a collar and cuff. If the position proved unstable, closed reduction was re-attempted or internal fixation performed. Conservative treatment was safe and effective, and the results comparable with other series that advocate internal fixation.

Child↗

PubMed1993

Mechanisms of the relaxant action of ketamine on isolated porcine trachealis muscle.

Ketamine is a potent bronchodilator, but its mode of action is unclear. We have studied the effect of ketamine on the peripheral vagus nerve motor pathway of isolated porcine trachealis muscle. Postsynaptic nicotinic cholinergic receptors of the intramural ganglia were stimulated selectively with 1,1-dimethyl-4-phenyl-piperazinium iodide, post-ganglionic nerve fibres with electrical field stimulation (in the presence of hexamethonium) and muscarinic cholinergic receptors with acetylcholine (in the presence of tetrodotoxin). Ketamine 10(-4) mol litre-1 significantly shifted the concentration-response curves of acetylcholine (P < 0.02) and electrical field stimulation (P < 0.001) to the right and abolished the response to 1,1-dimethyl-4-phenyl-piperazinium iodide (P < 0.02). Ketamine also caused a concentration-dependent relaxation of muscle strips precontracted with acetylcholine. This was unaffected by propranolol. Ketamine relaxed muscle strips precontracted with potassium chloride, in the absence and presence of atropine. We conclude that ketamine interacts with the peripheral vagus nerve by decreasing the excitability of the postsynaptic nicotinic receptors of the intramural ganglia, and by affecting the muscarinic receptor, smooth muscle, or both. Beta-2 adrenoceptors are not involved in the mechanism of relaxation.

Acetylcholine↗

PubMed1993

Postnatal adrenoreceptor maturation in porcine intrapulmonary arteries.

The effect of postnatal age on norepinephrine-induced alpha 2-adrenoreceptor-mediated release of endothelium-derived relaxing factor in porcine intramuscular pulmonary arteries was studied. Rings of pulmonary artery from fetal, newborn, 3-d-, 10-d-, 9-wk-, and 15-wk-old pigs with and without endothelium were suspended for isometric force measurement in Krebs-Ringer bicarbonate solution (37 degrees C, 95% O2-5% CO2). In 15- and 10-wk-old pigs, norepinephrine increased tone in arteries with and without endothelium but produced relaxations at high concentrations only in arteries with endothelium. These relaxations were not inhibited by the alpha 1-antagonist prazosin but were completely abolished by the alpha 2-antagonist yohimbine and the inhibitor of nitric oxide release N-omega-nitro-L-arginine methyl ester. This confirms that the norepinephrine-induced relaxations were due to alpha 2-mediated release of endothelium-derived relaxing factor. Arteries from only 50% of the 10-d-old animals showed endothelium-dependent relaxations, and at 3 d of age and younger no relaxations were seen. In animals less than 10 d old, only some of the vessels contracted to norepinephrine and the contractile response was diminished compared with 15-wk-old animals, whereas the response to prostaglandin F2 alpha and histamine was similar in the neonatal group (newborn, 3 d old, and 10 d old). This group showed a dose-dependent relaxation to nitric oxide, with 10-d-old animals more sensitive to nitric oxide than newborn animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

Efficient activation of transcription in yeast by the BPV1 E2 protein.

The full-length gene product encoded by the E2 open reading frame (ORF) of bovine papillomavirus type 1 (BPV1) is a transcriptional transactivator. It is believed to mediate its effect on the BPV1 long control region (LCR) by binding to motifs with the consensus sequence ACCN6GGT. The minimal functional cis active site, called the E2 response element (E2RE), in mammalian cells comprises two copies of this motif. Here we have shown that E2 can function in Saccharomyces cerevisiae by placing an E2RE upstream of a synthetic yeast assay promoter which consists of a TATA motif and an mRNA initiation site, spaced correctly. This E2RE-minimal promoter is only transcriptionally active in the presence of E2 protein and the resulting mRNA is initiated at the authentic start site. This is the first report of a mammalian viral transactivator functioning in yeast. The level of activation by E2 via the E2RE was the same as observed with the highly efficient authentic PGK promoter where the upstream activation sequence is composed of three distinct elements. Furthermore a single E2 motif which is insufficient in mammalian cells as an activation site was as efficiently utilized in yeast as the E2RE (2 motifs). Previous studies have shown that mammalian cellular activators can function in yeast and our data now extend this to viral-specific activators. Our data indicate however that while the mechanism of transactivation is broadly conserved there may be significant differences at the detailed level.

Base Sequence↗

PubMed1989

Topical ophthalmic exposure to rattlesnake venom.

An 18-year-old woman was struck in the eye from a distance of about 1 m by a stream of venom projected by a western diamond-back rattlesnake. She experienced an immediate burning sensation in the eye. The eye was irrigated first with tap water and later with a commercial eye wash solution. The patient's symptoms abated and no further eye injury was noted. Topical ophthalmic exposures to North American snake venom usually produce only transient symptoms, but the venom from tropical snakes has produced significant eye injury.

Adolescent↗