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Biomedical subjects

G Owens

Publications and source records attributed to G Owens.

At least 19 recordsLinked to original sources
PubMed2006

Alphavirus replicon approach to promoterless analysis of IRES elements.

Here we describe a system for promoterless analysis of putative internal ribosome entry site (IRES) elements using an alphavirus (family Togaviridae) replicon vector. The system uses the alphavirus subgenomic promoter to produce transcripts that, when modified to contain a spacer region upstream of an IRES element, allow analysis of cap-independent translation of genes of interest (GOI). If the IRES element is removed, translation of the subgenomic transcript can be reduced >95% compared to the same transcript containing a functional IRES element. Alphavirus replicons, used in this manner, offer an alternative to standard dicistronic DNA vectors or in vitro translation systems currently used to analyze putative IRES elements. In addition, protein expression levels varied depending on the spacer element located upstream of each IRES. The ability to modulate the level of expression from alphavirus vectors should extend the utility of these vectors in vaccine development.

Alphavirus↗
PubMed2006

A randomized trial of local anesthesia with intravenous sedation vs general anesthesia for the vaginal correction of pelvic organ prolapse.

The purpose of this study is to compare the feasibility of local anesthesia with IV sedation versus general anesthesia for vaginal correction of pelvic organ prolapse. Patients with pelvic organ prolapse who were scheduled for an anterior or posterior colporrhaphy, or an obliterative procedure, and who did not have a contraindication or preference to type of anesthesia were randomized to one of the two anesthesia groups. Nineteen patients were randomized to the general group and 21 patients were randomized to the local group. Mean operating room, anesthesia, and surgical time were similar in each group, and 10 patients in the local group bypassed the recovery room. Requests and doses of antiemetics, postoperative verbal numerical pain scores and length of hospital stay were similar between the two groups. Mean recovery room and total hospital costs were significantly lower in the local group. Local anesthesia with IV sedation is a feasible alternative for vaginal surgery to correct pelvic organ prolapse.

Aged↗
PubMed2004

Potent thyrotrophin receptor-blocking antibodies: a cause of transient congenital hypothyroidism and delayed thyroid development.

OBJECTIVE: We describe an infant with surprisingly severe neonatal hypothyroidism due to transplacental passage of thyrotrophin receptor (TSH-R)-blocking antibodies (TBAb). DESIGN AND METHODS: TBAb were detected using a cell line which stably expresses the human TSH-R and a cAMP-responsive luciferase reporter by their ability to inhibit TSH-stimulated luciferase expression. Potent TBAb were detected in maternal serum and initially in the infant's serum but, in the latter, TBAb decreased over time to within the reference range by 3-4 months of age, illustrating the transient nature of this condition. RESULTS: The thyroid function of this child did not return to normal on withdrawal of thyroxine therapy at 16 months of age when he developed transient compensated hypothyroidism. CONCLUSIONS: We propose that the presence of potent TBAb in utero and in the first weeks of life may have implications for the development of a normally sized thyroid gland. We have demonstrated the presence of TBAb in the mother's milk and, as far as we are aware, this is the first such report. However, the TBAb in the milk probably did not contribute significantly to hypothyroidism in the child, given the reducing antibody titre in his circulation.

Autoantibodies↗
PubMed2003

Rapsyn mutations in hereditary myasthenia: distinct early- and late-onset phenotypes.

Rapsyn mutations in 16 unrelated patients with a congenital/hereditary myasthenic syndrome were identified, and a mutation (N88K) common to each of them was found. Two distinct phenotypes were noted: early and late onset. The former is frequently associated with arthrogryposis multiplex congenita and life-threatening crises. The late-onset phenotype developed in adolescence or adulthood and was initially mistaken for seronegative myasthenia gravis. Recognition of this late-onset phenotype should prevent inappropriate immunotherapy.

Adolescent↗
PubMed2003

Chemistry of chromium in soils with emphasis on tannery waste sites.

Worldwide chromium contamination of soils has arisen predominantly from the common practice of land-based disposal of tannery wastes under the assumption that the dominant species in the tannery waste would be the thermodynamically stable Cr(III) species. However, significant levels of toxic Cr(VI) recently detected in surface water and groundwater in India, China, Australia, and elsewhere raise critical questions relating to current disposal criteria for Cr-containing wastes. It now appears that despite the thermodynamic stability of Cr(III), the presence of certain naturally occurring minerals, especially Mn oxides, can enhance oxidation of Cr(III) to Cr(VI) in the soil environment. This factor is of public concern because at high pH, Cr(VI) is bioavailable, and it is this form that is highly mobile and therefore poses the greatest risk of groundwater contamination. A review of the current literature indicates that extensive research has been performed on the speciation of Cr in soil, the effect of pH on soil solution concentrations of Cr(III) and Cr(VI), soil adsorption phenomenon of Cr species, redox reactions, and transformation of Cr(II) and Cr(VI) together with remediation strategies to decontaminate Cr-contaminated soils. Most of the studies were conducted using an uncontaminated soil artificially spiked with Cr, and very limited research has been conducted in the contaminated soil environment. Furthermore, studies on tannery waste contaminated soils are limited, and obviously a serious gap of knowledge exists in understanding the influence of long-term tannery waste contamination on Cr behavior in soil.

Chromium↗
PubMed2001

In utero gene delivery by intraamniotic injection of a retroviral vector producer cell line in a nonhuman primate model.

In utero gene therapy (IUGT) offers the promise of treating a wide variety of genetic diseases before the development of disease manifestations. The most convenient and potentially easiest method of targeting the fetus is through injection into the amniotic cavity. For long-term correction of genetic defects, retroviral vectors have great potential as a tool for gene therapy strategies. However, retroviral vectors are limited by growth to low titers. In an attempt to increase the amount of vector particles delivered and assess the potential of intraamniotic administration, we injected a retroviral vector producer cell line encoding the lacZ gene into the amniotic fluid of a nonhuman primate model. After birth the infants were analyzed for vector-mediated transduction. Two of four fetuses were successfully transduced, with transgene expression detected in the esophagus, trachea, and stomach. In some sections of tissue, nearly 100% of the cells lining the lumen of these tissues were positive for transduction. Although successful, the limited number of tissues in which transduction was observed led to an in vitro analysis of the effects of amniotic fluid (AF). The presence of amniotic fluid inhibited transduction by 99%. AF affected both the transducing activity of the vector and the health of the packaging cells. The negative effects of AF were gestational age dependent; greater inhibition was observed from AF collected at later stages of pregnancy. The fact that transduction was successful despite these negative effects indicates that this approach is a promising strategy for gene therapy.

3T3 Cells↗
PubMed2001

Cloning of the 18S rDNA gene, an internal transcribed spacer, and the 5' region of the 28S rDNA gene of Cope's gray treefrog, Hyla chrysoscelis.

The location of rDNA genes on the chromosomes of most species is identical within that species, usually occurring on the same chromosome or chromosomes. This is not the case in Cope's gray treefrog, Hyla chrysoscelis, where the rDNA genes are polymorphic for chromosome location. The occasions leading to this polymorphism have yet to be determined. The first step in understanding the nature of the polymorphism is the characterization of the ribosomal gene array. Here we describe the cloning, sequencing, and confirmation, by fluorescence in situ hybridization, of the 18S rDNA gene, a region which includes the end of the 18S rDNA gene, an internal transcribed spacer, and a portion of the 5' end of the 28S rDNA gene in H. chrysoscelis.

5' Untranslated Regions↗
PubMed2000

The redox-sensitive transcriptional activator OxyR regulates the peroxide response regulon in the obligate anaerobe Bacteroides fragilis.

The peroxide response-inducible genes ahpCF, dps, and katB in the obligate anaerobe Bacteroides fragilis are controlled by the redox-sensitive transcriptional activator OxyR. This is the first functional oxidative stress regulator identified and characterized in anaerobic bacteria. oxyR and dps were found to be divergently transcribed, with an overlap in their respective promoter regulatory regions. B. fragilis OxyR and Dps proteins showed high identity to homologues from a closely related anaerobe, Porphyromonas gingivalis. Northern blot analysis revealed that oxyR was expressed as a monocistronic 1-kb mRNA and that dps mRNA was approximately 500 bases in length. dps mRNA was induced over 500-fold by oxidative stress in the parent strain and was constitutively induced in the peroxide-resistant mutant IB263. The constitutive peroxide response in strain IB263 was shown to have resulted from a missense mutation at codon 202 (GAT to GGT) of the oxyR gene [oxyR(Con)] with a predicted D202G substitution in the OxyR protein. Transcriptional fusion analysis revealed that deletion of oxyR abolished the induction of ahpC and katB following treatment with hydrogen peroxide or oxygen exposure. However, dps expression was induced approximately fourfold by oxygen exposure in DeltaoxyR strains but not by hydrogen peroxide. This indicates that dps expression is also under the control of an oxygen-dependent OxyR-independent mechanism. Complementation of DeltaoxyR mutant strains with wild-type oxyR and oxyR(Con) restored the inducible peroxide response and the constitutive response of the ahpCF, katB, and dps genes, respectively. However, overexpression of OxyR abolished the catalase activity but not katB expression, suggesting that higher levels of intracellular OxyR may be involved in other physiological processes. Analysis of oxyR expression in the parents and in DeltaoxyR and overexpressing oxyR strains by Northern blotting and oxyR'::xylB fusions revealed that B. fragilis OxyR does not control its own expression.

Amino Acid Sequence↗
PubMed1996

A comparative study of the clinical efficacy of nedocromil sodium and placebo. How does cromolyn sodium compare as an active control treatment?

Nedocromil sodium and cromolyn sodium are the only two currently available nonsteroid anti-inflammatory agents for treatment of asthma. Clinical differences between the two agents remain under continuous investigation with reports differentiating the two on the basis of atopy of the patient and reversibility of bronchoconstriction. This study investigated the efficacy of nedocromil sodium (4 mg, qid) for treatment of mild-to-moderate asthma in comparison to placebo using cromolyn sodium (2 mg, qid) as an active control treatment. Patients were primarily allergic asthmatics (with at least 15% reversibility) previously maintained on a regimen of regular bronchodilator therapy. During a 2-week run-in period, the patient's slow-release theophylline therapy was removed, and the patients were randomized to treatment after deterioration of asthma control (asthma symptom summary score of 3 for 7 of the 14 days). After 8 weeks of treatment, patients were returned to as occasion requires bronchodilator therapy, as per the 2-week baseline period. The results demonstrate that patients treated with nedocromil sodium showed statistically significant improvements during the primary time period (mean weeks 3 through 8) over placebo-treated patients as evidenced by all indexes of asthma symptoms, pulmonary function measures, and decreased bronchodilator reliance (p<0.05). Patients treated with cromolyn sodium demonstrated similar improvements over placebo-treated patients. Comparisons between nedocromil sodium and cromolyn sodium showed the two agents to be comparable in this group of primarily allergic patients with reversible disease. Between-group differences were noted for 3 of the 13 variables (nighttime asthma, FEV1, and forced expiratory flow rate between 25 % and 75% of the FVC) in favor of cromolyn sodium when the data were pooled during the primary time period. The number of patients missing 1 or more days from work/school/regular activity due to asthma was significantly fewer compared with placebo, and favoring nedocromil sodium over cromolyn sodium. No differences were observed among the three treatments for adverse events. This study demonstrated that in primarily allergic patients with reversible airways disease, nedocromil sodium and cromolyn sodium are both significantly more effective than placebo for treatment of mild-to-moderate asthma.

Activities of Daily Living↗
PubMed1994

The ETO portion of acute myeloid leukemia t(8;21) fusion transcript encodes a highly evolutionarily conserved, putative transcription factor.

The 8;21 translocation, t(8;21)(q22;q22.3), is seen only in acute myelogenous leukemia and is characteristically associated with the M2 subtype. Subsequent to our identification of the t(8;21) breakpoint region on chromosome 21, we reported that the translocation results in the fusion of the AML1 gene on chromosome 21 with a novel gene on chromosome 8 which we called ETO (for eight twenty-one). Recently, the AML1 portion of the fusion protein has been shown to correspond to the DNA-binding and dimerization domains of the mouse gene, polyoma enhancer binding protein 2 alpha B (pebp 2 alpha B). We report here the complete sequence of the ETO portion of the fusion transcript as compiled from complementary DNAs from a t(8;21) AML patient and compare this with the ETO sequence from a mouse brain transcript. The deduced amino acid sequences are 99% identical. ETO has several features consistent with it being a transcription factor. The ETO sequence is different from the portion of PEBP 2 alpha B it replaces in the AML1/ETO fusion protein, except for their common high content of proline, serine, and threonine residues. Because neither the putative zinc fingers nor the TAF110 homology domain of ETO is present in PEBP2 alpha B, one might expect functional differences in the ability of AML1/ETO protein to affect the levels of transcription of genes normally regulated to some degree by AML1 (PEBP2 alpha B) during myeloid differentiation. The relatively high levels of ETO in developing brain suggest that it could be involved in the regulation of some aspect of neural proliferation or differentiation.

Amino Acid Sequence↗
PubMed1994

Inhibition of IL-1 release from human monocytes and suppression of streptococcal cell wall and adjuvant-induced arthritis in rats by an extract of Tripterygium wilfordii Hook.

1. It was investigated whether an extract of Tripterygium wilfordii Hook f (TW) inhibits IL-1 production by monocytes and suppresses the development of IL-1-dependent arthritis induced in rats with streptococcal cell wall and adjuvant. 2. TW preferentially inhibited IL-1 alpha and IL-1 beta production by bacterial lipopolysaccharide (LPS)-stimulated human monocytes with IC50 of approximately 1 microgram/ml. 3. Oral administration of TW dose-dependently suppressed joint swelling and structural damage in streptococcal cell wall-induced arthritis (ED50 = 20 mg/kg/day) and in adjuvant-induced arthritis (ED50 = 46 mg/kg/day for developing and 8 mg/kg/day for established arthritis).

Animals↗
PubMed1994

Varicella-zoster virus (VZV) transcription during latency in human ganglia: construction of a cDNA library from latently infected human trigeminal ganglia and detection of a VZV transcript.

The entire varicella-zoster virus (VZV) genome appears to be present in latently infected human ganglia, but the extent of virus DNA transcription is unknown. Conventional methods to study virus gene transcripts by Northern (RNA) blotting are not feasible, since ganglia are small and VZV DNA is not abundant. To circumvent this problem, we prepared radiolabeled cDNA from ganglionic RNA, hybridized it to Southern blots containing VZV DNA, and demonstrated the presence of a transcript within the SalI C fragment of the virus genome (R. Cohrs, R. Mahalingam, A. N. Dueland, W. Wolf, M. Wellish, and D. H. Gilden, J. Infect. Dis. 166:S24-S29, 1992). To further map VZV transcripts, in the work described here we constructed a cDNA library from poly(A)+ RNA obtained from latently infected human ganglia. Phage DNA isolated from the library was used in PCR amplifications to detect VZV-specific inserts. The specificity of the PCRs was provided by selection of a primer specific for VZV gene 17, 18, 19, 20, or 21 and a second vector-specific primer. VZV gene 21-specific sequences were identified by PCR amplification. The PCR product contained the XhoI cloning site and poly(A)+ sequences between vector and VZV gene 21 sequences. The sequence motif at the 3' end of VZV gene 21, determined by cloning and sequencing of the PCR product, consisted of 49 to 51 nucleotide bases of 3'-untranslated DNA, the termination codon for the VZV gene 21 open reading frame, and DNA sequences reading into the VZV gene 21 open reading frame.

Aged↗
PubMed1993

Patient simulation using seamless digital video.

This manuscript describes a method for using digital-video technology to create patient simulations in which the simulated patient is always active on the computer screen. We outline the technical method we have developed, and we present the lessons learned in applying the method to develop a prototype patient simulation.

Computer-Assisted Instruction↗
PubMed1992

Isolated diffusing capacity reduction in systemic sclerosis.

OBJECTIVE: To determine the long-term outcome of patients with systemic sclerosis (SSc) and an isolated reduction in the diffusing capacity for carbon monoxide (DLCO) at the time of initial evaluation. METHODS: Patients with an isolated reduction in DLCO (i.e., normal forced vital capacity [FVC] and normal ratio of the forced expiratory volume in one second [FEV1] to the FVC) on initial evaluation were identified from among 815 patients with SSc who were carefully followed up throughout their illness. We requested that patients have repeat pulmonary function testing (PFT), and the outcomes of these tests, as well as cardiopulmonary and survival outcomes, were determined. RESULTS: An isolated reduction in DLCO, with a normal FVC was detected in 152 (19%) of the 815 patients. A subset of those with an isolated reduction in DLCO (11%) developed isolated pulmonary hypertension and had severely reduced survival rates. Pulmonary hypertension was strongly associated with an initial DLCO of less than 55% of predicted normal and a FVC (% predicted)/DLCO (% predicted) ratio of greater than 1.4. Among all patients in whom this ratio was greater than 1.4, 22% developed isolated pulmonary hypertension, compared with only 2% of those whose ratio was less than 1.4 (P less than 0.01). Of the 152 patients with isolated DLCO reduction, 73 (48%) underwent PFTs a mean of 5.4 years (range 2.0-13.2) after the initial PFT. Only 6 (8%) of these 73 patients ever had serious pulmonary disease: 5 had isolated pulmonary hypertension, and 1 had severe pulmonary fibrosis. Half of the patients with a low initial DLCO demonstrated a significant improvement (greater than 20%) at followup testing that could not be explained by the demographic, clinical, or laboratory findings at the first visit. CONCLUSION: Isolated reduction in DLCO is a frequent abnormality in SSc. Overall, it is associated with a good prognosis for survival and for pulmonary morbidity. A small subset of patients (11%) who have a very low DLCO (less than 55% of predicted) have developed isolated pulmonary hypertension, all of whom had limited scleroderma.

Carbon Monoxide↗
PubMed1990

Studies of the initiation of myelination by Schwann cells.

The rapid morphologic changes in Schwann cells and in their relationships to axons during the transition from the premyelinating to the myelinating state have been known for more than 15 years. The sorting of axons by dividing Schwann cells, the establishment of a 1:1 relationship between a postmitotic Schwann cell, and the onset of myelin sheath formation have all been described in detail. However, the chain of molecular events and mechanisms by which these morphologic changes are regulated has not been elucidated. In this chapter we have reviewed results that strongly suggest that the adhesion molecule L1 is one of the important determinants that mediate the elongation of the Schwann cell along the axon, and the extension of Schwann processes to engulf axons. Thus, L1 functions to promote the spreading of the Schwann cell process over the surface of the axon. L1 does not appear to be exclusively involved in the adhesion of Schwann cells to axons, in the activation of Schwann cell proliferation by axons, or in the induction of synthesis of extracellular matrix proteins. The results from the anti-L1 blocking experiments further provided clues for an understanding of how the expression of GalC and MAG, which are both likely to be involved in the initiation of myelination, are regulated. These results imply that the overall regulation of expression of these early myelin components could require controls other than a single signaling mechanism derived from contact with axons. We propose that the deposition of basal lamina or one of its components could also be involved. Finally, the results from anti-GalC-blocking experiments indicated that GalC is involved in the mechanism of early growth of the myelin spiral.

Animals↗