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Biomedical subjects

C Burgess

Publications and source records attributed to C Burgess.

At least 19 recordsLinked to original sources
PubMed2001

Identification of a novel human fibroblast growth factor and characterization of its role in oncogenesis.

The fibroblast growth factor (FGF) family of signaling molecules has been implicated in normal developmental and physiological processes, as well as in human malignancy. Using a homology-based genomic DNA mining process, we identified a human gene encoding a novel member of the FGF family, that we designate FGF-20. The FGF-20 cDNA was isolated, and its sequence confirmed the gene prediction. FGF-20 is expressed in normal brain, particularly the cerebellum, and in some cancer cell lines. Recombinant FGF-20 protein induces DNA synthesis in a variety of cell types and is recognized by multiple FGF receptors. Ectopic expression of FGF-20 in NIH 3T3 cells renders the cells transformed in vitro and tumorigenic in nude mice. These results underscore the utility of mining genomic DNA databases and reveal FGF-20 to be a novel oncogene that may play a role in human cancer.

3T3 Cells↗
PubMed2001

Formation of N-nitroso-N-methylurea in various samples of smoked/dried fish, fish sauce, seafoods, and ethnic fermented/pickled vegetables following incubation with nitrite under acidic conditions.

In continuation of our previous studies on N-nitroso-N-methylurea (NMU) formation in cured meats following incubation with nitrite at gastric pH, we extended the investigation to other foods mentioned in the title of this paper. The main objective was to determine whether these foods have the potential to form NMU at pH's that can be found in the human stomach. This was done by nitrosating an aliquot (5 g for fish sauce, 10 g for the others) of each with 7.25 microM to 1.59 mM levels of sodium nitrite for 2 h at room temperature at pH 0.8--1.5 and measuring the amounts of NMU formed. Of the samples tested, fish sauce formed 2--712 ng of NMU, followed in decreasing order by herring (<0.3--688 ng); dried anchovy, shrimp, and other fishes (<0.3--134 ng); crab and lobster paté (<0.3--342 ng); sardines (6--59 ng); oysters and mussels (11--31 ng); dried squid (3--47 ng); kimchi (7--107 ng); and Japanese pickled radish (<0.3--72 ng). Incorporation of 200-2000 ppm of ascorbic acid in the fish sauce and other foods, prior to nitrosation, appreciably inhibited such NMU formation. Although previous researchers in China reported NMU formation in nitrosated samples of fish sauce, this is the first reported formation of NMU upon nitrosation of the other foods mentioned above, and the first reported inhibition of such formation by added ascorbic acid.

Animals↗
PubMed2000

Agony and ecstasy: a review of MDMA effects and toxicity.

BACKGROUND: Ecstasy is a recreational drug with an anecdotal reputation for safety. However, reports of adverse effects and fatalities have increased in the medical and popular press. METHOD: Literature search and review. RESULTS: Acute Ecstasy toxicity does not appear to be due to overdose and cannot be solely attributed to the nature of the usual ambient environment. Adverse effects include hyperthermia, seizures, cardiac arrhythmias, hepatotoxicity, hyponatraemia and many psychiatric disorders. Ecstasy causes serotonergic neurotoxicity in the brains of animals at doses close to those used by humans, but its long-term effect on the human brain is unknown. CONCLUSION: Ecstasy toxicity should be considered in the differential diagnosis of a variety of medical and psychiatric conditions. Given its popularity, both the acute and the potential long-term effects are a cause for concern.

Acute Disease↗
PubMed2000

Investigation on the possible formation of N-nitroso-N-methylurea by nitrosation of creatinine in model systems and in cured meats at gastric pH.

N-Nitroso-N-methylurea (NMU) is a highly potent direct-acting carcinogen that has been shown to induce cancer in a number of animal species. Although previous research has indicated that nitrosation of creatinine (CRN), a common constituent of meats, dried fish, and seafoods, can form traces of NMU, there is uncertainty as to (1) the yield of NMU and (2) whether detectable amounts of NMU can be formed from cured meats following nitrosation under acidic conditions given the low residual levels of nitrite found in cured meats at the present time. Lack of sensitive and specific analytical methods most likely has hindered progress in research in these areas. An HPLC postcolumn denitrosation-thermal energy analyzer technique and a GC-MS confirmation technique were developed for the determination of NMU in cured meats. Both techniques are highly sensitive (0.5 and 0.03 ppb, respectively) and specific. The optimum pH for NMU formation from CRN ranged between pH 1 and pH 3, and the yields of NMU under variable reactant concentrations ranged between 0.00004 and 0.0046%. When 27 samples of various cured meats (10 g aliquots each) were acidified with HCl (final pH values of 0.8-2.5) and incubated at room temperature for 2 h, without any additional nitrite, 24 gave results below detectable levels but 3 formed 2-26 ng of NMU/10 g of meat. Incubation of the negative meats with additional nitrite (50-500 microg/g of meat) formed 0.6-176 ng of NMU/10 g of sample. Although the amounts of NMU formed were extremely small, this seems to be the first reported formation of NMU from cured meats with and without additional nitrite.

Creatinine↗
PubMed2000

Suggestion difficulty as a hypothesized moderator of the relation between absorption and suggestibility: a new spectral analysis.

Measures of hypnotic suggestibility and absorption were administered to 146 participants in the guise of different experiments. A spectral analysis was performed by correlating the difficulty of individual hypnotic suggestions with the magnitude of the association between suggestions and absorption. Contrary to the two-component model, absorption was not more highly correlated with passing difficult suggestions than easier suggestions. This was confirmed by a meta-analysis of this and other spectral analysis studies. In addition, cross-study correlations revealed that the magnitude of the association between absorption and individual suggestions is highly variable, rendering the two-component model very difficult to test. These findings indicate that discrepant results in previous spectral analyses may have been due to low reliability of associations with individual scale items, as well as the relatively small number of correlations that constitute the raw data of these analyses.

Female↗
PubMed2000

An evaluation of near patient tests for detecting herpes simplex virus type-2 antibody.

OBJECTIVES: To examine the "in use" test characteristics of the POCkit "near patient" HSV-2 rapid test for the detection of HSV-2 IgG antibodies for use in the clinic. This test relies on a visual interpretation of the result. METHODS: 2093 serum samples, 229 from UK and 919 from Italian genitourinary medicine clinic patients and 945 from obstetric and gynaecology clinic patients in Italy were tested. Tests were carried out according to manufacturers' protocol in the United Kingdom and Italy. Three readers independently recorded a score for each test carried out and the results were compared. RESULTS: In the UK study, the three readers disagreed on the result on 5.2% of tests. In the Italian study, there was disagreement in 10.2% of tests. CONCLUSIONS: This study has demonstrated a problem in the subjective nature of the interpretation of the POCkit HSV-2 test. It highlights the need for adequate training of clinic staff and the need for clinics to adopt policies of quality assurance and ongoing monitoring which will ensure the validity and accuracy of this clinic based test.

Antibodies, Viral↗
PubMed2000

A computational approach to modeling population differences.

Four experiments were conducted to determine whether the Hyperspace Analogue to Language (HAL) model of semantic memory could differentiate between two different populations. An analysis of the differences in densities (or average distances between word neighbors in semantic space) in HAL matrices--generated from text corpora derived from younger and older adults--confirmed that HAL was able to distinguish between the two age groups. This difference was again detected when structured interview data were used to build the corpora. A third experiment, designed to test the specificity of HAL in detecting differences between groups, did not detect any difference in the densities of the memory representations when older adults generated both the test corpora. The final experiment, conducted on the language of adults with Alzheimer's and normal adults, again demonstrated that HAL could discriminate between the two populations. These results suggest that HAL is capable of modeling, on the basis of changes in mean density, some of the differences between populations without modifying the model itself but, rather, by changing the text corpus from which the model creates its representations in semantic space.

Adult↗
PubMed1999

Cerebral hemispheric mechanisms linking ambiguous word meaning retrieval and creativity.

The deferral of ambiguity resolution has been thought to be an important component of creativity. The time course of priming of dominant and subordinate meanings of ambiguous words was investigated using a divided visual field priming paradigm with subjects that varied on a measure of creativity. The Wallach-Kogan similarities subtest was used to group 72 subjects into three levels of verbal creativity to compare their performance on the ambiguity resolution task (Burgess & Simpson, 1988a). Results suggest that both the left and right hemispheres contribute to the maintenance of multiple word meanings in highly creative subjects, while less creative subjects show sustained subordinate priming only in the right hemisphere or no sustained subordinate priming. These results support an interactive, collaborative theory of verbal creativity (Bogen & Bogen, 1969) and suggest that there are important individual differences that expand on the basic time course model of hemispheric processing (Burgess & Simpson, 1988a).

Brain↗
PubMed1999

Beta-agonists: what is the evidence that their use increases the risk of asthma morbidity and mortality?

In this article, studies that have examined the effects on morbidity and mortality of beta-agonist drugs are reviewed. With regard to morbidity, there is considerable evidence that the regular use of beta-agonist drugs as a class could potentially lead to worsening asthma control because of the effects on bronchial hyperresponsiveness, the development of tolerance and reduced protection against provoking stimuli, an increased allergen load, and masking of the symptoms of deteriorating asthma. Despite these effects, the short-acting beta-agonist drugs albuterol and terbutaline and the long-acting beta-agonist drugs salmeterol and formoterol have, in general, not been associated with a significant worsening of asthma control or an increased frequency of severe attacks. In contrast, there is evidence that the regular use of isoproterenol and fenoterol may lead to worsening asthma control. With regard to deaths, available evidence indicates that the high-dose preparations of isoproterenol and fenoterol are associated with increased mortality and were the major causes of the epidemics of asthma mortality observed in some countries. The increased risk of death associated with isoproterenol and fenoterol is probably the result of both long-term effects with their regular use leading to worsening asthma control and acute effects resulting from their overuse in the situation of a life-threatening attack of asthma. In contrast, the use of the short-acting beta-agonists albuterol and terbutaline is not associated with an increased risk of mortality. Although this lack of risk may also apply to formoterol and salmeterol, in the absence of sufficient studies specifically addressing the risk of death, this remains uncertain.

Adrenergic beta-Agonists↗
PubMed1999

The effect of time course and context on the facilitation of semantic features in the cerebral hemispheres.

Two divided visual field priming experiments were designed to determine the nature of lexical retrieval in the cerebral hemispheres by studying the facilitation of semantic features of unambiguous nouns. Unambiguous nouns have a single meaning, yet semantic features associated with these nouns may vary in the degree to which they are compatible with this single meaning (e.g., LAMB-WOOL as compared with LAMB-CHOPS). Results suggest that the left hemisphere selects both strongly and weakly associated semantic features that are compatible with the dominant representation of the noun. Dominance compatibility, rather than association strength, seems to be the more important factor for deciding what features are maintained in the left hemisphere. In contrast, the right hemisphere maintains more varied information, including features that are less compatible with the dominant representation (Experiment 1) and context information (Experiment 2).

Brain↗
PubMed1999

Large-scale databases of proper names.

Few tools for research in proper names have been available--specifically, there is no large-scale corpus of proper names. Two corpora of proper names were constructed, one based on U.S. phone book listings, the other derived from a database of Usenet text. Name frequencies from both corpora were compared with human subjects' reaction times (RTs) to the proper names in a naming task. Regression analysis showed that the Usenet frequencies contributed to predictions of human RT, whereas phone book frequencies did not. In addition, semantic neighborhood density measures derived from the HAL corpus were compared with the subjects' RTs and found to be a better predictor of RT than was frequency in either corpus. These new corpora are freely available on line for download. Potentials for these corpora range from using the names as stimuli in experiments to using the corpus data in software applications.

Databases as Topic↗
PubMed1998

The extrapulmonary effects of increasing doses of formoterol in patients with asthma.

OBJECTIVE: To assess the cardiovascular and metabolic responses to increasing doses of formoterol administered from a dry powder inhaler. METHODS: Twenty patients with mild to moderate asthma were given 12, 24, 48 and 96 microg of formoterol or a matched placebo on separate days. The doses were administered using a randomised, cross-over, double-blind design. The effects on heart rate, blood pressure, electromechanical systole (QS2I), the electrocardiographic QTc interval, plasma potassium (K); blood glucose and FEV1 were assessed prior to, and for 9 h following each dose. RESULTS: There was no difference between the maximum effects of formoterol 12 microg and placebo; the 24 microg dose significantly decreased plasma K (-0.2 mmol x l(-1)) and increased blood glucose (1.8 mmol x l(-1)) compared to placebo. The two highest doses affected most of the variables with the 96 microg dose being significantly different from placebo for all indices, heart rate (9 beats x min(-1)), systol BP (4 mmHg), diastolic BP (-3 mmHg), QS2I (-11 ms), QTc (17 ms), plasma K (-0.5 mmol x l(-1)) and blood glucose (2.6 mmol x l(-1)). All doses of formoterol increased FEV1. CONCLUSION: Although there were dose-dependent effects on the extrapulmonary measurements, only the effects at the highest dose may be of clinical significance.

Administration, Inhalation↗
PubMed1998

Experiential scoring for the Waterloo-Stanford Group C scale.

A scale is presented that assesses subjective experiences associated with the test suggestions contained in the Waterloo-Stanford Group C scale (WSGC), a group adaptation of the Stanford Hypnotic Susceptibility Scale: Form (SHSS:C). This scale, along with the standard behavioral scoring system of the WSGC, was given to 926 students at the University of Connecticut. Normative data from this sample indicate that the experiential scoring scale is both reliable and valid as a measure of suggestibility. It is suggested that it may be useful to supplement behavioral scoring with experiential scoring when the WSGC is used.

Adult↗
PubMed1998

False negativity by an anti-HIV assay kit (IMx 8B32) and evaluation of its replacement (IMx 8C98).

False negativity in a commercial anti-HIV kit (IMx HIV-1/HIV-2 3rd Generation Plus (code 8B32) was investigated, and the kit that superseded it (IMx HIV-1/HIV-2 III Plus, code 8C98) was evaluated. In a comparison on 574 freshly collected anti-HIV-1-positive specimens, 97.2% were more reactive in 8C98 than in 8B32; 35.5% were more than twice as reactive and 8.5% were more than four times as reactive. In 8B32, the signal from 55 specimens selected because of weak reactivity was enhanced 1.5 to 8.8 times by preliminary heating at 56 degrees C for 30 min. The reactivity of the 55 heated sera was then similar to that of the same specimens tested without heat treatment in the 8C98 assay. Reactivity in 8B32 was also increased in 66 of 76 (at least twofold in 20) randomly chosen anti-HIV-positive serum specimens by the addition of EDTA (10 mM final concentration). One of these specimens was false negative (signal:cutoff (S:CO) ratio 0.76) in 8B32, though its reactivity was restored by addition of EDTA (S:CO ratio 9.54). These findings indicate that the inhibitory effect that originally led to false negative findings in 8B32 was probably due to complement activity, and that the same activity was present in the freshly collected specimens used here to evaluate the replacement IMx anti-HIV assay (8C98). The specimen panel employed to evaluate 8C98 included 1,892 anti-HIV-positive and 779 anti-HIV-negative specimens. There were no false negative reactions. The lowest S:CO ratio observed was 6.2 and only 17 (0.2%) anti-HIV-positive specimens gave ratios less than 10. Nine unreproducible false positive reactions arose, all possibly attributable to specimen carryover by the IMx instrument. The performance of 8C98 was also compared with that of 10 other current anti-HIV kits using 21 sets of seroconversion specimens (127 specimens in total), and five performance assessment panels (92 specimens in total) comprised mostly of single bleeds from recent seroconverters. IMx 8C98 was the second most sensitive assay. We found no evidence that the 8C98 kit was prone to the effect that had given rise to false negative results in its predecessor (8B32).

AIDS Serodiagnosis↗