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Biomedical subjects

J C Turner

Publications and source records attributed to J C Turner.

At least 19 recordsLinked to original sources
PubMed2001

Development of a routine method for the determination of trace metals in whole blood by magnetic sector inductively coupled plasma mass spectrometry with particular relevance to patients with total hip and knee arthroplasty.

BACKGROUND: Joint-replacement surgery has revolutionized the treatment of osteoarthritis and is still the most effective therapy. A recent clinical trend reintroducing metal-on-metal bearing surfaces has in turn stimulated a requirement for accurate measurement of the concentrations of relevant metals in both pre- and postoperative patients. Thus, there is a need for cost-effective, multielement methods for trace metal analysis in whole blood to monitor possible increases in wear metal concentrations. METHODS: A method was developed to allow routine analysis of whole blood samples for molybdenum, cobalt, chromium, and nickel. Sample preparation consisted of a simple 1:10 dilution of whole blood with a solution of 10 mL/L Triton X-100, 0.0002 mol/L EDTA, and 0.01 mol/L ammonium hydroxide. Final determination was performed by a double-focusing magnetic sector inductively coupled plasma mass spectrometer operated in medium-resolution mode (resolution, 3400). Online addition of rhodium was used for internal standardization. RESULTS: Detection limits in whole blood were 0.06 microg/L for chromium, cobalt, and molybdenum and 0.30 microg/L for nickel. Base concentrations of 0.22, 0.17, 0.62, and 0.99 microg/L for chromium, cobalt, molybdenum, and nickel, respectively, in whole blood have been found. Polyatomic interferences on all four elements have been shown to be resolved from the analyte masses by use of a resolution of >3000. CONCLUSIONS: The simple, rapid method of sample preparation is effective in minimizing potential contamination and enables 60 samples (run time, 8 h) to be analyzed before cleaning the instrument is necessary. A resolution >3000 was sufficient to separate polyatomic interferences from the masses of interest. The method was used to analyze a large number of blood samples taken from primary patients awaiting total hip arthroplasty. The method is sensitive enough to provide base concentrations for chromium, cobalt, and molybdenum in whole blood. The results for nickel were compromised by high signals for blank samples.

Arthroplasty, Replacement, Hip↗
PubMed2000

When are we better than them and they worse than us? A closer look at social discrimination in positive and negative domains.

This article argues that in-group favoritism occurs on positive and negative dimensions only when the dimensions of comparison provide an appropriate and meaningful basis for self-other definition, that is, when traits comparatively and normatively fit in-group-out-group categorizations. Three studies are reported in which groups were evaluated on positive or negative traits that varied in their degree of normative fit to in-group and out-group identity. In line with predictions, fit rather than stimulus valence was the crucial determinant of (a) in-group favoritism and (b) absolute level of differentiation between groups. Implications of the findings for explanations of positive-negative asymmetry and broader understandings of intergroup discrimination are discussed.

Adult↗
PubMed1998

Low plasma levels of adrenocorticotropic hormone in patients with acute influenza.

Plasma levels of adrenocorticotropic hormone (ACTH) and cortisol were measured in young adults with influenza virus type A (H3N2) infection for whom cultures were positive and in comparable controls without symptoms or other evidence of illness. The mean plasma ACTH level +/- SE in 19 patients with acute influenza was 13.5 +/- 2.1 pg/mL compared with 23 +/- 3.2 pg/mL in 11 controls (P = .02). Mean plasma ACTH levels +/- SE had risen to 21 +/- 4.1 pg/mL in specimens obtained from patients during convalescence. The mean plasma cortisol level +/- SE in patients with acute influenza was 13.7 +/- 1.4 micrograms/dL compared with 10.8 +/- 1.0 micrograms/dL in controls (P = not significant). ACTH levels in individual controls were relatively higher than their cortisol levels, but ACTH levels in patients tended to be lower than cortisol levels in paired specimens. These findings suggest that influenza virus type A infection may have an inhibitory effect on the production or release of ACTH.

Acute Disease↗
PubMed1997

Epidemiologic evidence for Lancefield group C beta-hemolytic streptococci as a cause of exudative pharyngitis in college students.

The isolation rates of strains of group C beta-hemolytic streptococci from throat swab cultures of patients with exudative pharyngitis, the common cold, and healthy controls were compared. By using a cohort study design in a college health service, patients with exudative pharyngitis were retrospectively identified by description of tonsillar exudate on chart review. Patients with rhinoviral infection were prospectively identified during a common cold study. Healthy controls were prospectively recruited from patients presenting with noninfectious conditions. Isolation of Lancefield group A and C beta-hemolytic streptococci from throat cultures was used as an outcome measurement. A total of 265 students (62% female; average age 20.2 years) with exudative pharyngitis were identified. A total of 75 students (60% female; average age, 21.7 years) from a common cold study with rhinoviral infection were identified. A total of 162 students (53% female; average age, 22.6 years) were recruited as healthy controls. Group A beta-hemolytic streptococci were isolated from 5% of patients with pharyngitis but none of those with rhinovirus (P = 0.045) and none of the controls (P = 0.007). Group C Streptococcus dysglactiae subsp. equisimilis was isolated from 11% of patients with pharyngitis but none of those with rhinovirus (P = 0.006) and 2% of controls (P = 0.001). Lancefield group C Streptococcus anginosus was isolated from 8% of patients with pharyngitis but 3% of those with rhinovirus (P = 0.18) and 1% of controls (P = 0.006). Heavier growth of colonies on the primary culture plate was observed for patients from whom S. equisimilis and group A beta-hemolytic streptococci were isolated. Lancefield group C beta-hemolytic streptococci appear to be associated with exudative pharyngitis in college students.

Adult↗
PubMed1996

M proteins of group C streptococci isolated from patients with acute pharyngitis.

We studied 15 strains of group C (Streptococcus equi subsp. equisimilis) [corrected] isolated from the throats of college students with acute pharyngitis and 5 strains isolated from patients with noninfectious problems. Nineteen of the 20 strains resisted phagocytic killing during incubation in normal human blood, suggesting that they might express M proteins. Genomic DNA from all 20 strains hybridized with a probe corresponding to the carboxyterminal one-third of the group A M-protein gene emm24, a region that is highly conserved among M proteins of group A and group G streptococci. The DNA sequences of the N-terminal (variable) regions of the M-protein-encoding genes from two disease-associated group C isolates and one control isolate were determined. The predicted amino acid sequences of the two pharyngitis strains were identical and were 88% homologous to the amino acid sequence of a group G M-protein gene. The predicted terminal amino acid sequence of the control strain does not correspond to any such sequences in the GenBank database. All three strains studied possess the conserved region domain common to class I group A M-protein types epidemiologically associated with rheumatic fever. These studies demonstrate the presence of M proteins in strains of S. equi subsp. equisimilis [corrected] isolated in cases of endemically occurring acute pharyngitis. Certain of these proteins are similar to those of group G streptococci, while others may represent new M types. The similarity in structure and function between M proteins of nonrheumatogenic serogroups and those of rheumatogenic group A streptococci suggests that factors other than or in addition to M protein per se are likely involved in the pathogenesis of rheumatic fever.

Acute Disease↗
PubMed1995

Social categorization and group homogeneity: changes in the perceived applicability of stereotype content as a function of comparative context and trait favourableness.

Using the Katz-Braly checklist subjects (N = 65) assigned five traits to a national group and estimated the percentage of group members who had those traits. This was either an in-group (Australians) or an out-group (Americans), and subjects either judged that group alone (one-group conditions) or also estimated the percentage of people from the other nation (the United States or Australia, respectively) who had those same traits (two-group conditions). Across one-group conditions there was a significant out-group homogeneity effect with traits being seen to apply to more Americans than Australians, but there was no such effect across the two-group conditions. These findings were predicted on the basis of self-categorization theory's analysis of the role of comparative context in determining level of social categorization. Across two-group conditions non-stereotypic traits were also applied to fewer in-group than out-group members. This result suggests that trait favourableness is an important normative-motivational determinant of perceived homogeneity. A second experiment (N = 297) confirmed this point through an additional manipulation of the favourableness of checklist traits. This study also replicated the effect for comparative context. Implications for the analysis of social categorization, perceived group homogeneity and stereotyping are discussed.

Adult↗
PubMed1994

Promoting responsible sexual behavior through a college freshman seminar.

A sexual health curriculum has been incorporated into our university's freshman seminar. The effectiveness of this program in changing sexuality-related knowledge, attitude, and behavior in college freshmen was studied. Seven hundred eighty-six freshmen students enrolled in 37 randomly selected English classes were surveyed at baseline and at 3 months. Survey outcome measurements included: knowledge regarding sexually transmitted diseases (STDs), attitudes about sexual behavior, and behaviors including the frequency of barrier contraceptive use, abstinence, and the number of sexual partners. At postintervention, mean knowledge, attitude, and behavior scores were significantly higher for those simultaneously enrolled in the freshman seminar than for those not enrolled. Abstinence among males in the seminar increased. White males in the seminar were more likely to be abstinent or to use a condom than nonwhites. Females not participating in the intervention reported increased frequency of "never" using condoms and decreased frequency of condom use at last intercourse. Students participating in a sexual health curriculum in a college freshman seminar report less frequent high-risk sexual behaviors than students not participating in the seminar.

Adolescent↗
PubMed1993

Reduction in sexual risk behaviors among college students following a comprehensive health education intervention.

Sexually active college students are at risk of contracting sexually transmitted diseases, including HIV infection. As a result, health education initiatives to prevent these infections are commonplace, but few controlled research studies have evaluated behavioral changes as a result of on-campus sex education. In a nonrandomized control trial, sexual risk behaviors of 341 students who had received a comprehensive health education intervention in a first-year seminar were compared with 227 students who were not enrolled in the seminar. The seminar curriculum included an intervention addressing facts about sexually transmitted diseases, safer sex, values, decision making, and assertiveness skills. Sexual abstinence (no sexual intercourse), number of sexual partners, consistent condom use, and methods of contraception were assessed at baseline and after 3 months. Compared with students who had not received the intervention, men in the seminar reported increased sexual abstinence but no change in consistent condom use; the women in the intervention group reported no change in sexual abstinence but an increase in consistent condom use. Women who had not received the intervention reported never using a condom more frequently than women who had received the intervention. The health education intervention on a college campus was associated with short-term reduction in sexual risk behaviors, but the reduction varied according to the students' gender.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Role of group C beta-hemolytic streptococci in pharyngitis: epidemiologic study of clinical features associated with isolation of group C streptococci.

All Lancefield group C beta-hemolytic streptococci isolated over 12 months from college students with clinical pharyngitis and age-matched healthy controls were identified. Clinical features of upper respiratory tract infection and pyogenic pharyngitis as well as colony counts were tabulated for each patient according to throat culture results. Of 1,480 patients, Lancefield group C Streptococcus equisimilis was isolated from 45 (3%) patients and Streptococcus anginosus ("Streptococcus milleri") was isolated from 164 (11.1%) patients. Patients from whom S. equisimilis was isolated had clinical features more suggestive of pyogenic infection than did patients from whom S. anginosus was isolated. Colony counts on primary throat culture plates from patients from whom S. equisimilis and Streptococcus pyogenes were isolated were higher than those from patients from whom S. anginosus was isolated. This study presents epidemiologic evidence supporting a role for S. equisimilis in causing pharyngeal infection and for S. anginosus as representing part of the normal oropharyngeal flora.

Adult↗
PubMed1992

Latex agglutination testing directly from throat swabs for rapid detection of beta-hemolytic streptococci from Lancefield serogroup C.

A latex agglutination method for the rapid detection of beta-hemolytic streptococci from Lancefield serogroup C in throat swabs from 403 university students with symptomatic pharyngitis was evaluated. Compared with culture, the rapid test was poorly sensitive (34.4%) but very specific (98.4%) in detecting group C beta-hemolytic streptococci. The sensitivity of the rapid test improved with an increasing quantity of growth on culture.

Adolescent↗
PubMed1991

Use of long catheters for multipatient anesthetic monitoring at high respiratory frequencies.

Anesthetic gases from several patients can be monitored simultaneously with a centrally located mass spectrometer. Such monitoring requires catheters from patient to spectrometer that are several meters long. Scamman (J Clin Monit 1988; 4:227-229) found that when the respiratory frequency is high, as with infants, the CO2 signal from the patient is unacceptably distorted during passage down the catheter. This is due to Taylor dispersion of the input signal. An outline of the theory of Taylor dispersion is given. The equations describe the interaction between the velocity distribution (which, in laminar flow, is parabolic) and the radial diffusion of CO2. This interaction keeps a tracer signal together in a pulse, as it moves down the tube with the mean velocity, spreading somewhat as it proceeds. How much does an initially sharp signal become blurred? The spread of such a signal when it reaches the detector, measured in time, can be expressed in various ways. Measurement is complicated, however, by the fact that the gas pressure may fall by as much as a factor of 10 along the line. The resultant expansion and acceleration of the gas cannot be ignored. A full treatment of this complication is given elsewhere, but the following simple equation is described: delta t = 3.54 x 10(-3) l [(1 + R2)/(1 - R2)]1/2. Typically, the spread time is up to a quarter of a second for catheters of 50 m, such as used by Scamman. This is comparable with the period of CO2 rise and fall for infants and explains the serious distortion in wave form that Scamman+ found.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesiology↗
PubMed1990

Association of group C beta-hemolytic streptococci with endemic pharyngitis among college students.

Throat cultures were performed throughout 2 school years to determine whether non-group A beta-hemolytic streptococci (NGA BHS) could be isolated more frequently in 232 college students who had symptomatic pharyngitis than from 198 age-matched controls with noninfectious problems. Duplicate throat swabs were inoculated onto plates that contained sheep blood agar, one plate being incubated in a 5% CO2 atmosphere and the other in an anaerobic environment. The BHS were grouped using latex agglutination. Among the NGA BHS, only those from group C were isolated significantly more often among the patients compared with the controls (26% vs 11%). Quantitative colony counts of isolates of group C BHS were generally higher among patients than controls. Patients with group C BHS had fever, exudative tonsillitis, and anterior cervical adenopathy significantly more frequently than did patients who had throat cultures that were negative for group C BHS. Group C BHS were epidemiologically associated with endemic pharyngitis in this college student population.

Adult↗
PubMed1990

A dominant mutation in Arabidopsis confers resistance to auxin, ethylene and abscisic acid.

We have screened a large population of M2 seeds of Arabidopsis thaliana for plants which are resistant to exogenously applied indole-acetic acid (IAA). One of the resistant lines identified in this screen carries a dominant mutation which we have named axr2. Linkage analysis indicates that the axr2 gene lies on chromosome 3. Plants carrying the axr2 mutation are severe dwarfs and display defects in growth orientation of both the shoot and root suggesting that the mutation affects some aspect of gravitropic growth. In addition, the roots of axr2 plants lack root hairs. Growth inhibition experiments indicate that the roots of axr2 plants are resistant to ethylene and abscisic acid as well as auxin.

Abscisic Acid↗
PubMed1990

Studies on selenate and selenite absorption by sheep ileum using an everted sac method and an isolated, vascularly perfused system.

1. Using everted sacs of sheep ileum, selenate uptake was shown to be more rapid than selenite uptake. 2. Sulphate, thiosulphate and ouabain all inhibited the uptake of selenate. A Na+K(+)-ATPase is probably responsible for energizing the ileal brush-border transport of selenate. 3. The isolated, vascularly perfused ileum was shown to absorb selenate more rapidly than selenite. 4. The perfusion system described would appear to be a useful tool for studying the kinetics of intestinal absorption and the measurement of metabolic transformations within the mucosa.

Animals↗
PubMed1990

Knowing what to think by knowing who you are: self-categorization and the nature of norm formation, conformity and group polarization.

We contrast two theoretical approaches to social influence, one stressing interpersonal dependence, conceptualized as normative and informational influence (Deutsch & Gerard, 1955), and the other stressing group membership, conceptualized as self-categorization and referent informational influence (Turner, Hogg, Oakes, Reicher & Wetherell, 1987). We argue that both social comparisons to reduce uncertainty and the existence of normative pressure to comply depend on perceiving the source of influence as belonging to one's own category. This study tested these two approaches using three influence paradigms. First we demonstrate that, in Sherif's (1936) autokinetic effect paradigm, the impact of confederates on the formation of a norm decreases as their membership of a different category is made more salient to subjects. Second, in the Asch (1956) conformity paradigm, surveillance effectively exerts normative pressure if done by an in-group but not by an out-group. In-group influence decreases and out-group influence increases when subjects respond privately. Self-report data indicate that in-group confederates create more subjective uncertainty than out-group confederates and public responding seems to increase cohesiveness with in-group - but decrease it with out-group - sources of influence. In our third experiment we use the group polarization paradigm (e.g. Burnstein & Vinokur, 1973) to demonstrate that, when categorical differences between two subgroups within a discussion group are made salient, convergence of opinion between the subgroups is inhibited. Taken together the experiments show that self-categorization can be a crucial determining factor in social influence.

Adolescent↗