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Biomedical subjects

L J Taylor

Publications and source records attributed to L J Taylor.

At least 19 recordsLinked to original sources
PubMed2001

Salmonella typhimurium translocates flagellin across intestinal epithelia, inducing a proinflammatory response.

This study investigated whether soluble paracrine factors mediated Salmonella-induced IL-8 expression in polarized model intestinal epithelia. We found that the basolateral media of model epithelia that had been apically infected with Salmonella typhimurium for a short period (10 minutes) could activate IL-8 secretion in virgin model epithelia, demonstrating that a proinflammatory factor (PIF) was indeed present. Initial characterization found that PIF was a heat-stable protein with a molecular mass of about 50 kDa that acts on the basolateral, but not apical, surface of model intestinal epithelia to elicit IL-8 secretion. PIF was not present in the media of model epithelia stimulated with other inducers of IL-8 secretion (TNF-alpha or carbachol) but was present in S. typhimurium supernatants, indicating PIF is of bacterial origin. PIF was purified from bacterial culture supernatants by anion/cation exchange chromatography and SDS-PAGE and found by using microsequencing to be the protein flagellin. In support of this finding, flagellin-deficient S. typhimurium mutants did not secrete detectable levels of PIF (i.e., a bioactivity that induced IL-8 secretion when placed basolaterally on model epithelia). Furthermore, viable flagellin-deficient mutant organisms (fliC/fljB and flhD) failed to elicit IL-8 secretion when added apically to model intestinal epithelia. These findings indicate that translocation of flagellin across epithelia, subsequent to apical epithelial-S. typhimurium interaction, is likely a major means of activating a mucosal inflammatory response.

Cell Line↗
PubMed2000

Structural requirements for the specific recognition of an m7G mRNA cap.

7-Methylguanosine (m(7)G), also known as the mRNA "cap", is used as a molecular tag in eukaryotic cells to mark the 5' end of messenger RNAs. The mRNA cap is required for several key events in gene expression in which the m(7)G moiety is specifically recognized by cellular proteins. The configurations of the m(7)G-binding pockets of a cellular (eIF4E) and a viral (VP39) cap-binding protein have been determined by X-ray crystallography. The binding energy has been hypothesized to result from a pi-pi stacking interaction between aromatic residues sandwiching the m(7)G base in addition to hydrogen bonds between the base and acidic protein side chains. To further understand the structural requirements for the specific recognition of an m(7)G mRNA cap, we determined the effects of amino acid substitutions in eIF4E and VP39 cap-binding sites on their affinity for m(7)GDP. The requirements for residues suggested to pi-pi stack and hydrogen bond with the m(7)G base were examined in each protein by measuring their affinities for m(7)GDP by fluorimetry. The results suggest that both eIF4E and VP39 require a complicated pattern of both orientation and identity of the stacking aromatic residues to permit the selective binding of m(7)GDP.

Amino Acid Substitution↗
PubMed2000

Induction of the cellular E2F-1 promoter by the adenovirus E4-6/7 protein.

The adenovirus type 5 (Ad5) E4-6/7 protein interacts directly with different members of the E2F family and mediates the cooperative and stable binding of E2F to a unique pair of binding sites in the Ad5 E2a promoter region. This induction of E2F DNA binding activity strongly correlates with increased E2a transcription when analyzed using virus infection and transient expression assays. Here we show that while different adenovirus isolates express an E4-6/7 protein that is capable of induction of E2F dimerization and stable DNA binding to the Ad5 E2a promoter region, not all of these viruses carry the inverted E2F binding site targets in their E2a promoter regions. The Ad12 and Ad40 E2a promoter regions bind E2F via a single binding site. However, these promoters bind adenovirus-induced (dimerized) E2F very weakly. The Ad3 E2a promoter region binds E2F very poorly, even via a single binding site. A possible explanation of these results is that the Ad E4-6/7 protein evolved to induce cellular gene expression. Consistent with this notion, we show that infection with different adenovirus isolates induces the binding of E2F to an inverted configuration of binding sites present in the cellular E2F-1 promoter. Transient expression of the E4-6/7 protein alone in uninfected cells is sufficient to induce transactivation of the E2F-1 promoter linked to chloramphenicol acetyltransferase or green fluorescent protein reporter genes. Further, expression of the E4-6/7 protein in the context of adenovirus infection induces E2F-1 protein accumulation. Thus, the induction of E2F binding to the E2F-1 promoter by the E4-6/7 protein observed in vitro correlates with transactivation of E2F-1 promoter activity in vivo. These results suggest that adenovirus has evolved two distinct mechanisms to induce the expression of the E2F-1 gene. The E1A proteins displace repressors of E2F activity (the Rb family members) and thus relieve E2F-1 promoter repression; the E4-6/7 protein complements this function by stably recruiting active E2F to the E2F-1 promoter to transactivate expression.

Adenoviridae↗
PubMed1999

Nucleolar Arf sequesters Mdm2 and activates p53.

The Ink4/Arf locus encodes two tumour-suppressor proteins, p16Ink4a and p19Arf, that govern the antiproliferative functions of the retinoblastoma and p53 proteins, respectively. Here we show that Arf binds to the product of the Mdm2 gene and sequesters it into the nucleolus, thereby preventing negative-feedback regulation of p53 by Mdm2 and leading to the activation of p53 in the nucleoplasm. Arf and Mdm2 co-localize in the nucleolus in response to activation of the oncoprotein Myc and as mouse fibroblasts undergo replicative senescence. These topological interactions of Arf and Mdm2 point towards a new mechanism for p53 activation.

3T3 Cells↗
PubMed1998

Assessing the individual with asthma.

Seven to 20 million Americans have asthma. Deaths related to asthma have increased 46% from 1980 to 1989. Individuals with asthma who are at risk for adverse outcomes are those who have low incomes and poor access to health care, have psychosocial problems, and do not understand or fail to follow treatment regimens. Additional risk factors include hospitalization within the past year, a previous near-fatal asthma attack, and a history of intubation for asthma. Assessment and appropriate treatment can prevent fatalities associated with asthma, especially in the home setting.

Asthma↗
PubMed1997

Interpretation of arterial blood gases by nurses.

Many clinical nurses find the concept of acid/base balance confusing. This article presents a step-by-step approach to arterial blood gas (ABG) analysis. In addition, the components of ABGs (pH, PCO2 and HCO3) are presented; metabolic and respiratory abnormalities (acidosis and alkalosis) are discussed in relation to cause and signs and symptoms; the concept of compensation is reviewed; the degrees of compensation are explained; the five steps of ABG analysis are outlined; and practice problems are provided and explained. By using this approach, the nurse can analyze the ABG values confidently and make a wise choice about appropriate nursing actions.

Acidosis↗
PubMed1997

Caring for the patient with a gastrostomy/jejunostomy tube.

A gastrostomy or jejunostomy (G or J) tube is useful for feeding malnourished patients and is preferred to prolonged use of total parenteral nutrition. Because enteral feeding has become commonplace in both the hospital and home setting, it is vital that health care workers instruct caregivers on the treatment of individuals with G tubes and/or J tubes. Many problems can be prevented when caregivers know how to care for the patient and troubleshoot potential concerns.

Community Health Nursing↗
PubMed1996

Androgen regulation of ribosomal RNA synthesis in LNCaP cells and rat prostate.

Androgen-dependent growth of prostate tissue has been well documented. An additional prerequisite for cellular growth is the accumulation of ribosomes. It is thus reasonable to hypothesize that ribosomal DNA (rDNA) transcription in prostate tissue must be stimulated by androgen either directly or indirectly. This hypothesis was tested using both LNCaP cells, an androgen-dependent tissue culture line and in a rat animal model. Nuclear run-on assays confirmed that the administration of DHT to LNCaP cells resulted in a two- to three-fold increase in the rate of rRNA synthesis when compared to cells maintained in the absence of androgen. Enzymatic analysis and Western blots were carried out to measure the amount (activity and mass) of RNA polymerase I in DHT treated LNCaP cells. These assays demonstrated that neither the catalytic activity of RNA polymerase I nor the amount of the enzyme varied in response to DHT. However, Western blots revealed that the amount of the auxiliary RNA polymerase I transcription factor UBF, was significantly increased (two- to three-fold) in cells grown in the presence of DHT. Similar experiments were carried out with prostatic tissue obtained from orchiectomized rats maintained on either placebo or testosterone pellets. In this model, both the catalytic activity as well as the amount of RNA polymerase I protein decreased. However, in agreement with the tissue culture model, UBF protein decreased in prostates from orchiectomized rats and was maintained in animals supplemented with testosterone. These lines of evidence are consistent with the hypothesis that androgens stimulate rRNA synthesis by increasing the quantities of the components of the rDNA transcription system.

Animals↗
PubMed1995

Activity of RNA polymerase I transcription factor UBF blocked by Rb gene product.

The protein encoded by the retinoblastoma susceptibility gene (Rb) functions as a tumour suppressor and negative growth regulator. As actively growing cells require the ongoing synthesis of ribosomal RNA, we considered that Rb might interact with the ribosomal DNA transcription apparatus. Here we report that (1) there is an accumulation of Rb protein in the nucleoli of differentiated U937 cells which correlates with inhibition of rDNA transcription; (2) addition of Rb to an in vitro transcription system inhibits transcription by RNA polymerase I; (3) this inhibition requires a functional Rb pocket; and (4) Rb specifically inhibits the activity of the RNA polymerase I transcription factor UBF (upstream binding factor) in vitro. This last observation was confirmed by affinity chromatography and immunoprecipitation, which demonstrated an interaction between Rb and UBF. These results indicate that there is an additional mechanism by which Rb suppresses cell growth, namely that Rb directly represses transcription of the rRNA genes.

Amino Acid Sequence↗
PubMed1994

Anterior lumbar fusion: results, assessment techniques and prognostic factors.

One hundred and fifty-one patients underwent anterior interbody lumbar spinal fusion for intractable back pain. A solid bony fusion was obtained in 76%. The method of outcome assessment profoundly affected the results; whereas 68% of patients rated themselves as significantly improved by the procedure, only 40% achieved a good or excellent result on the more objective low-back outcome score. Patients who underwent a second procedure did not do well, and "salvage" surgery is not recommended. Posterior distraction instrumentation neither increased the rate of union nor improved the final results. The rate of fusion was influenced by the presence of a compensation claim. Compensation status and psychological disturbance at presentation were significant prognostic factors. Psychological disturbance at review had a profound effect on the outcome and patient satisfaction ratings. It is recommended that future studies employ a recognised outcome score and that the analysis specifically includes compensation status and psychological disturbance.

Adult↗
PubMed1994

Anterior lumbar fusion. A comparison of noncompensation patients with compensation patients.

One hundred fifty-one patients had an anterior interbody lumbar spinal fusion for intractable back pain. A solid bony fusion was obtained in 76% of the patients. Of patients unemployed before surgery, 50% had returned to work at review. Sixty-eight percent of patients rated themselves as significantly improved by the procedure. Posterior distraction instrumentation neither increased the rate of union nor improved the final results. Compensation status and psychological disturbance at presentation were significant prognostic factors. Psychological disturbance at review had a profound effect on the outcome and patient satisfaction ratings. It is recommended that in future studies compensation status and psychological disturbances are explicitly included in the outcome statistics.

Adolescent↗
PubMed1993

A clinical trial of prostaglandin E2 in recurrent aphthous ulceration.

Thirty-five patients suffering from minor recurrent aphthous ulceration (RAU) entered a single-phase double-blind clinical trial of treatment with topical prostaglandin E2 (PGE2). The PGE2 was applied as a gel at a dose of 0.3 mg twice daily for 10 days. The vehicle alone acted as control. Patients were examined on days 1, 3, 5, 7 and 10 and also maintained daily diary cards. Of the 33 patients (94%) who completed the study, 18 had been allocated the active PGE2 and 15 the placebo. The two volunteers who failed to complete were excluded on technical grounds related to the strict study design and did not withdraw on the basis of adverse reactions to the trial preparation. Patients using the active PGE2 gel experienced significantly fewer new lesions than those on placebo (P < 0.05) over the 10-day trial period. There were no significant differences between the PGE2 and placebo gels in terms of speed of healing or pain relief of established aphthous ulcers. Prostaglandin E2 may, therefore, have useful prophylactic activity in RAU.

Administration, Topical↗
PubMed1993

Rheological basis of oral characteristics of fluid and semi-solid foods: a review.

Oral viscosity plays an important role in the textural appreciation of fluid and semi-solid foods. Oral assessments of viscosity, thickness, stickiness and sliminess correlate with both small-deformation and large-deformation rheological measurements. Small-deformation measurements of viscosity at an oscillatory frequency of 50 rad.s-1 have the highest correlation with assessed thickness of texture but there is still much speculation as to what forces actually operate in the mouth.

Drinking↗
PubMed1993

An evaluation of surveillance methods for detecting infections in hospital inpatients.

Eight selective surveillance methods were compared with a reference method for their ability to detect hospital infections in patients was also assessed. In the reference method, case records were reviewed three times a week, and during the 11-month period of study, 668 infections were identified amongst 3326 patients. Three hundred and thirty-eight were community acquired infections (CAI) and 330 were hospital acquired infections (HAI). The time for data collection was 18.1 h per 100 beds per week. Of the selective surveillance methods, those based on the review of treatment and temperature charts detected the highest proportion (70%) of CAI; and the review of microbiology reports with regular ward liaison identified the highest proportion (71%) of HAI. The time for data collection in the eight methods ranged from 1.2 h per 100 beds per week to 6.5 h per 100 beds per week. After considering the sensitivity for identifying patients with HAI and time for data collection, the review of microbiology reports with regular ward liaison was judged to be an effective and efficient method of surveillance.

Cross Infection↗
PubMed1993

Introduction of laboratory based ward liaison surveillance of hospital infection into six district general hospitals.

A previous study demonstrated that laboratory based ward liaison surveillance (LBWLS) of hospital infection was an effective and efficient method. The method involved the follow-up of positive microbiology reports by the review of patient records and liaison with ward nursing staff to consider whether any patients had infection. Here we report the introduction of LBWLS into six district general hospitals to determine whether it is feasible to use this method on an everyday basis. The time required for data collection was assessed and the method was compared with a reference method in one hospital to check its ability to detect infections. To assess reproducibility two infection control nurses (ICNs) performed LBWLS independently, but concurrently, for 5 weeks. The method could be used in all hospitals studied; however, the time for data collection ranged from 3.0 to 6.8 h/100 beds per week. In comparison with the reference method, LBWLS detected 15/41 (37%) of community acquired infections and 30/43 (70%) of hospital acquired infections. In the reproducibility assessment 72 patients were identified by both ICNs. There was agreement about the infected/non-infected status of 65 of these patients. The mean pair agreement and Kappa statistic were 0.88 and 0.72. Laboratory based ward liaison was readily used in all hospitals and was reproducible.

Adolescent↗