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Biomedical subjects

T J Quinn

Publications and source records attributed to T J Quinn.

At least 19 recordsLinked to original sources
PubMed2004

There is no evidence of an association in children and teenagers between the apolipoprotein E epsilon4 allele and post-traumatic brain swelling.

Traumatic brain injury (TBI) is an important cause of mortality and disability in children and teenagers. A particular feature of the neuropathology at post-mortem is brain swelling. The cause of the swelling in some cases is not known, while in others it is associated with traumatic axonal injury or hypoxia. Apolipoprotein E (APOE) epsilon4 allele is known to be an important genetic determinant of outcome in children after TBI. We hypothesized a relationship between possession of APOEepsilon4 and diffuse traumatic brain swelling. A total of 165 cases aged between 2 and 19 years were identified from the department's tissue archive. APOE genotype was determined by polymerase chain reaction (PCR) in 106 cases. Bilateral swelling was present in 44 cases (11 with APOEepsilon4), unilateral swelling in 25 cases (7 with APOEepsilon4) and in 36 cases (9 with APOEepsilon4) there was no evidence of brain swelling. There was no significant relationship between possession of APOEepsilon4 and the presence of cerebral swelling (chi(2) = 0.09, df = 2, P = 0.96). The 95% confidence interval for difference in proportions with swelling in those with and without the APOE epsilon4 is -19% to 22%. Thus, a significant relationship was not found between diffuse brain swelling and possession of APOEepsilon4, and in this cohort of patients there was an identifying cause of the brain swelling in all cases.

Adolescent↗
PubMed2002

Physiological variables at lactate threshold under-represent cycling time-trial intensity.

BACKGROUND: The importance of lactate threshold (LT) as a determinant of performance in endurance sports has been established. In addition, it has been shown that during running and selected other endurance competitions, athletes perform at a velocity and VO2 slightly above LT for the duration of the event. Prior work indicates however, that this may not be true during a cycling time-trial (TT). This investigation sought to compare physiological variables during a 20-k TT with those corresponding to the athlete's LT. METHODS: Thirteen male cyclists (22.7+/-0.8 yrs; 180.6+/-8.0 cm; 77.1+/-10.0 kg; 8.3+/-2.5% fat; 4.9+/-2.2 l x min(-1), VO2max) participated in the study. Subjects performed a graded protocol starting at 150 Watts (W) to determine LT (2 mmol x L(-1) above baseline) which consisted of 20 W increases every 4-min. Following an 8 min-recovery, subjects cycled at the wattage corresponding to LT-20 W for 1 min and then workload increased 20 W every minute until volitional exhaustion to determine VO2max x On a separate occasion a self-paced, 20-k TT was completed. RESULTS: Mean values of blood lactate, HR and % HRmax, VO2 and % VO2max, and power output throughout the 20-k TT were greater (p<0.01) than those at LT. During the TT these cyclists performed at an intensity well above LT (blood lactate=252.0+/-0.1%, HR=9.4+/-0.03%, %HRmax=9.2+/-0.15%, VO2=26.5+/-0.7%, %VO2max=17.2+/-0.08% and power out-put=14.8+/-0.14% above LT) for over 30 min. CONCLUSIONS: Therefore, while LT may be highly correlated to performance, it may not be representative of race pace for a cycling TT, and may be questionable as a benchmark used to prescribe training intensity for competitive TT-cycling.

Adult↗
PubMed2001

A new determination of G using two methods.

We present the results of a measurement of G made with a torsion-strip balance used in two substantially independent ways. The two results agree to within their respective uncertainties; the correlation coefficient of the two methods is -0.18. The result is G = 6.675 59(27)x10(-11) m(3) kg(-1) s(-2) with a standard uncertainty of 4.1 parts in 10(5). Our result is 2 parts in 10(4) higher than the recent result of Gundlach and Merkowitz.

Journal Article↗
PubMed2001

Impact of starting strategy on cycling performance.

In order to determine an optimal starting technique, the first four-min of two 20 km time trials (TT) were manipulated. Thirteen competitive, male cyclists (22.7 +/- 0.8 yr, 180.6 +/- 2.2 cm; 77.1 +/- 2.8kg; 8.3+/-0.7% fat; 4.9+/-0.21 x min(-1), 71.7+/-1.4% of VO2max) performed three, 20 km TTs. The pace of the first TT was self-selected (SS). Min 1-4 of the subsequent, randomly assigned TTs were performed 15% below and 15% above the average power output (PO) of min 1-4 of the SS TT, subjects then completed the TT as quickly as possible. As a percent change from the SS TT, the 15% below TT was (p < 0.05) faster than 15% above TT. Lactic acid values at min 4 of the 15% below TT (4.87+/-0.73mM x l(-1)) were lower (p<0.05) than both SS TT (9.78+/-1.05mM x l(-1)) and 15% above TT (11.54+/-1.00mM x l(-1)). Following min 4 to the finish there were no differences in VE, HR, or RPE. However, VO2, VO2 with respect to lactic acid threshold, and PO were all elevated in the 15% below TT as compared to both SS TT and 15% above TT. The initially high LA resulting from the starting strategies of the SS TT and 15% above TT may have reduced the work capacity of active muscle.

Adult↗
PubMed2001

Physiological determinants of cross-country ski racing performance.

PURPOSE: Previous laboratory testing has identified the importance of upper-body aerobic and anaerobic power to cross-country skiing performance. The purpose of this investigation was to extend laboratory research into a field setting to identify predictors of performance through ski-specific testing. METHODS: Thirteen male collegiate skiers performed three field-testing sessions on roller skis to establish lactate threshold (LT) and ski economy (ECON) and maximal oxygen uptake (SK VO(2max)) and a 1-km double-pole time trial (UBTT) to determine peak upper-body oxygen uptake (UB VO(2)). As a measure of skiing performance, the subjects performed a 10-km skating time trial (TT) and were ranked according to competitive season performance (RANK). RESULTS: Significant correlations (P < 0.05) were found between SK VO(2max), LT VO(2), UB VO(2), and RANK (r = -0.66 to -0.84) and TT time (r = -0.74 to -0.79), as well as ECON to RANK (r = 0.57) and TT time (r = 0.68). Time to complete the UBTT (UB time) exhibited the strongest correlation to both RANK (r = 0.95) and TT time (r = 0.92). Multiple regression analyses revealed that UB time was the best predictor of RANK and TT time, as demonstrated by the significant beta values (0.77, P < 0.001, and 0.79, P < 0.001, respectively). The importance of the UB component was further seen in that UB time was still the best predictor of performance when the subjects were divided into two distinct groups of greater and lesser competitive ability. CONCLUSIONS: These findings identify the importance of the upper body component to cross-country skiing performance, suggesting a need to focus on upper-body conditioning within a well-rounded endurance training program. Additionally, the UBTT exhibits potential as a simple field test to predict cross-country skiing performance over more sophisticated and costly laboratory and field testing.

Adolescent↗
PubMed2001

Exercise and lactation: are they compatible?

Lactation is an energy-demanding physiological process for the maternal organism and life-giving for the offspring. Likewise, exercise is an energy-demanding process. This review addresses the compatibility of exercise during lactation. Human studies suggest no detrimental effect of exercise during lactation on milk composition and volume, infant growth and development, or maternal health. Studies also demonstrate improved cardiovascular fitness in lactating, exercising women and suggest a quicker return to pre-pregnancy body weight and a more positive sense of well-being, compared to sedentary controls. Findings from rodent studies, although of questionable value for humans, have generally shown no detrimental influence of exercise during pregnancy and lactation on pup growth and development. To date, findings suggest that exercise and lactation are compatible activities.

Animals↗
PubMed2001

TNF-alpha and IL-1 beta are not essential to the inflammatory response in LPS-induced airway disease.

To determine the role of tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta in the lower respiratory tract inflammatory response after inhalation of lipopolysaccharide (LPS), we conducted inhalation exposure studies in mice lacking expression of TNF-alpha and/or IL-1 receptor type 1 and in mice with functional blockade of these cytokines using adenoviral vector delivery of soluble receptors to one or both cytokines. Alterations in airway physiology were assessed by pulmonary function testing before and immediately after 4 h of LPS exposure, and the cellular inflammatory response was measured by whole lung lavage and assessment of inflammatory cytokine protein and mRNA expression. Airway resistance after LPS exposure was similarly increased in all groups of mice without evidence that blockade of either or both cytokines was protective from this response. Additionally, all groups of mice demonstrated significant increases in lung lavage fluid cellularity with a complete shift in the population of cells to a predominantly neutrophilic infiltrate as well as elevation in inflammatory cytokine protein and mRNA levels. There were no significant differences between the groups in measures of lung inflammation. These results indicate that TNF-alpha and IL-1 beta do not appear to have an essential role in mediating the physiological or inflammatory response to inhaled LPS.

Animals↗
PubMed2000

Twenty-four hour, ambulatory blood pressure responses following acute exercise: impact of exercise intensity.

OBJECTIVES: Mild to moderate acute, endurance exercise has generally been shown to reduce blood pressure (BP) in hypertensive (HT) individuals. Whether a slightly more strenuous bout of exercise can elicit a greater and more prolonged BP reduction is unknown. Therefore, the purpose of this study was to examine the effects of two, 30-min exercise bouts, conducted at 50% and 75% of maximal oxygen uptake (VO2max), on the quantity and quality of BP reduction over a 24-h period. METHODS: Sixteen, Stage 1 and 2 non-medicated, HT (8 men/8 women) subjects were matched with normotensive (NT) men and women (n = 16). All subjects were evaluated for VO2max with a symptom-limited treadmill test and then completed a 30-min exercise bout at 50% and 75% of VO2max as well as a control (no exercise) session in random fashion on separate days. Twenty-four hour ambulatory BPs were measured after both the exercise and control settings. Data was assessed at 1, 3, 6, 12, and 24 h post-exercise and control session. RESULTS: A repeated-measures ANOVA showed non-significant differences between HT men and women and that both exercise intensities, relative to the control session, significantly (P<0.05) reduced systolic (S) and diastolic (D) BPs. NT subjects showed non-significant reductions following both intensities. The reductions in the HT men and women averaged 4 and 9 mm Hg (SBP)/5 and 7 mm Hg (DBP) for 50% and 75%, respectively. On average, the HT subjects (men and women combined) maintained significant SBP reductions for 13 h after the 75% bout compared to 4 h after the 50% intensity. Likewise, DBP was reduced for an average of 11 h following the 75% bout compared to 4 h after the 50% intensity. CONCLUSIONS: These results suggest that an exercise bout conducted between 50-75% VO2max significantly decreases SBP and DBP in HT subjects and that a greater and longer-lasting absolute reduction is evident following a 75% of maximum bout of exercise.

Adult↗
PubMed2000

IL-10 reduces grain dust-induced airway inflammation and airway hyperreactivity.

To determine whether interleukin-10 (IL-10) could alter the development of grain dust-induced airway disease, we pretreated mice with either saline or IL-10 intravenously, exposed the mice to an inhalation challenge with corn dust extract (CDE), and measured inflammation and the development of airway hyperreactivity. Pretreatment with IL-10, in comparison to saline, reduced the concentration and percentage of polymorphonuclear cells in the lavage fluid 30 min after the inhalation challenge with CDE (P < 0. 05). In comparison to saline-treated mice, IL-10 did not significantly alter the degree of airway hyperreactivity 30 min after the exposure to CDE. IL-10-treated mice lavaged 18 h after challenge with CDE also exhibited a lower percentage of polymorphonuclear cells in the lavage fluid (P < 0.05) and had significantly less airway hyperreactivity than did mice pretreated with the saline placebo (P < 0.05). These findings indicate that exogenous IL-10 is effective in reducing airway inflammation and airway hyperreactivity due to the inhalation of CDE.

Animals↗
PubMed2000

Sonography of Morton's neuromas.

OBJECTIVE: The objective is to evaluate the sonographic characteristics of Morton's neuromas and the usefulness of sonography in detecting them. MATERIALS AND METHODS: Thirty intermetatarsal spaces were evaluated with sonography to diagnose Morton's neuromas. The prospective sonographic reports were correlated with surgical and pathologic findings. Each sonogram was then blindly and retrospectively reviewed to characterize mass echotexture, location, size, and continuity with the plantar digital nerve when present. RESULTS: Surgery revealed 27 Morton's neuromas, one synovial cyst with infarcted tissue, one ganglion cyst, and one giant cell tumor of the tendon sheath. The prospective sonographic reports correctly identified neuromas in 85% of the cases. Retrospectively, 79.2% (19/24) of the neuromas were characterized as hypoechoic compared with muscle, whereas 12.5% (3/24) were of mixed echotexture and 8.3% (2/24) were anechoic. One half (50%) of the neuromas were located dorsal to the plantar aspect of the metatarsal heads, and 50% were both dorsal and plantar to this level. No statistical difference in height and width was found between neuromas and nonneuromas; however, nonneuromas were statistically greater in length than neuromas. All 15 masses in which presumed plantar digital nerve continuity with the mass was identified were neuromas. CONCLUSION: Sonography can reveal a Morton's neuroma in 85% of cases. Identification of the presumed plantar digital nerve in continuity with the mass improves diagnostic confidence. The finding of an interdigital mass greater than 20 mm in length should raise suspicion of an abnormality other than a neuroma.

Adult↗
PubMed2000

Sonography and MR imaging of bifid median nerve with anatomic and histologic correlation.

OBJECTIVE: Imaging of a bifid median nerve has not been previously described in the radiology literature. We present three cases of bifid median nerve. The first is a patient with carpal tunnel syndrome seen on sonography and confirmed at surgery. The other two were found among 10 cadaveric specimens and were imaged with sonography and MR imaging. Confirmation of bifid median nerve in these two specimens was obtained using anatomic and histologic correlation. CONCLUSION: Sonography and MR imaging can allow effective diagnosis and delineation of a bifid median nerve in the wrist. This diagnosis is important to make before carpal tunnel release or other wrist surgeries are performed to avoid nerve injury. Furthermore, the sonographic size criteria for diagnosing carpal tunnel syndrome in nonbifid median nerves may not be accurate in evaluating bifid median nerves.

Adolescent↗
PubMed1999

Bacterial DNA or oligonucleotides containing unmethylated CpG motifs can minimize lipopolysaccharide-induced inflammation in the lower respiratory tract through an IL-12-dependent pathway.

To determine whether the systemic immune activation by CpG DNA could alter airway inflammation, we pretreated mice with either i.v. bacterial DNA (bDNA) or oligonucleotides with or without CpG motifs, exposed these mice to LPS by inhalation, and measured the inflammatory response systemically and in the lung immediately following LPS inhalation. Compared with non-CpG oligonucleotides, i. v. treatment with CpG oligonucleotides resulted in higher systemic concentrations of polymorphonuclear leukocytes, IL-10, and IL-12, but significantly reduced the concentration of total cells, polymorphonuclear leukocytes, TNF-alpha, and macrophage inflammatory protein-2 in the lavage fluid following LPS inhalation. The immunoprotective effect of CpG-containing oligonucleotides was dose-dependent and was most pronounced in mice pretreated between 2 and 4 h before the inhalation challenge, corresponding to the peak levels of serum cytokines. bDNA resulted in a similar immunoprotective effect, and methylation of the CpG motifs abolished the protective effect of CpG oligonucleotides. The protective effect of CpG oligonucleotides was observed in mice with either a disrupted IL-10 or IFN-gamma gene, but release of cytokines in the lung was increased, especially in the mice lacking IFN-gamma. In contrast, CpG DNA did not protect mice with a disrupted IL-12 gene against the LPS-induced cellular influx, even though CpG DNA reduced the release of TNF-alpha and macrophage inflammatory protein-2 in the lung. These findings indicate that CpG-containing oligonucleotides or bDNA are protected against LPS-induced cellular airway inflammation through an IL-12-dependent pathway, and that the pulmonary cytokine and cellular changes appear to be regulated independently.

Administration, Inhalation↗
PubMed1999

Does exercise intensity or diet influence lactic acid accumulation in breast milk?

PURPOSE: This study examined the relationships among diet, exercise intensity, and breast milk composition in lactating women. METHODS: Twelve lactating women were randomly assigned to either a high (N = 6; 5.03 g carbohydrate (CHO) x kg body mass (BM)(-1)) or moderate (N = 6; 3.89 g CHO x kg BM(-1)) carbohydrate diet. Milk and blood samples were collected before and after a nonexercise session (control) and maximal, lactic acid-threshold (LAT), and 20% below the LAT (LAT-20) intensities. RESULTS: The 30-min exercise LAT bout was more stressful than the 30-min LAT-20 bout (rating of perceived exertion (RPE) = 15 vs 12, respectively, P < 0.05). Milk LA was significantly higher at 0 min following maximal exercise in the high and moderate CHO groups (1.27+/-0.56 and 1.52+/-0.49 mM, respectively) and following LAT exercise (0.19+/-0.16 and 0.25+/-0.12 mM, respectively), when compared with the control session (0.08+/-0.03 and 0.09+/-0.05 mM, respectively). This was not observed following the LAT-20 exercise in the high and moderate CHO groups (0.11+/-0.04 and 0.12+/-0.08 mM, respectively). Elevated milk LA persisted in the 30-min collection point after maximal exercise only. There was no significant effect of dietary treatment on milk or blood LA at any of the collection points. CONCLUSIONS: In lactating women whose caloric needs are being met: 1) dietary CHO intake, within a practical range, does not influence LA levels in breast milk at rest or after exercise; 2) LA appearance in the milk is a function of exercise intensity; and 3) moderate intensity exercise (RPE = 12) will not increase breast milk LA levels.

Adult↗
PubMed1998

Lactic acid accumulation in cardiac patients performing circuit weight training: implications for exercise prescription.

OBJECTIVE: Because blood lactic acid (LA) levels may be important in prescribing exercise for cardiac patients, this study documented the LA response to four different circuit weight training (CWT) protocols and compared these responses to both maximal treadmill and LA threshold values. DESIGN: Intervention study following a crossover trial design. SETTING: A phase III community-based setting. PATIENTS: All subjects had documented cardiac disease and were volunteers. INTERVENTIONS: We used 40% and 60% of the one-repetition maximum (1-RM) for six exercises and 30 or 60sec of rest between each station, resulting in four protocols, performed in random order. A discontinuous treadmill test was conducted, and the LA threshold was determined. MAIN OUTCOME MEASURE: The main dependent variable was LA after each CWT protocol. RESULTS: No signs or symptoms suggestive of cardiovascular distress during any of the four CWT protocols were reported. A repeated-measures analysis of variance showed that the LA threshold value was significantly less than all four CWT protocols (p < .05). The CWT responses were also compared with the traditional LA threshold value of 4.0mmol/L, and both 60% protocols were significantly elevated (p < .05). CONCLUSION: Because no positive signs or symptoms were reported, we recommend starting stable cardiac patients on a CWT program with an initial load between 40% and 60% 1-RM and allowing at least 60sec of rest between exercises.

Aged↗
PubMed1998

Cardiac arrest as a result of intraabdominal extravasation of fluid during arthroscopic removal of a loose body from the hip joint of a patient with an acetabular fracture.

The case of a fifty-year-old man who suffered an isolated, associated, both-column fracture of the left acetabulum is presented. He underwent an uncomplicated open reduction and internal fixation through an ilioinguinal approach. A follow-up computed tomographic scan was performed postoperatively, which documented intraarticular fragments. Hip arthroscopy was performed to remove the fragments. During the procedure, arthroscopic fluid extravasated through the fracture site under pump pressure and resulted in an intraabdominal compartment syndrome that presented as cardiopulmonary arrest. An emergent exploratory laparotomy was performed to release the fluid and resume blood flow. Despite prolonged asystole, the patient survived without neurologic sequelae. The literature on compartment syndrome secondary to arthroscopic procedures is reviewed. Because of this previously unreported potentially lethal complication, we do not advocate hip arthroscopic procedures for acute or healing acetabular fractures.

Acetabulum↗
PubMed1998

Grain dust-induced lung inflammation is reduced by Rhodobacter sphaeroides diphosphoryl lipid A.

To further determine the importance of endotoxin in grain dust-induced inflammation of the lower respiratory tract, we evaluated the efficacy of pentaacylated diphosphoryl lipid A derived from the lipopolysaccharide of Rhodobacter sphaeroides (RsDPLA) as a partial agonist of grain dust-induced airway inflammation. RsDPLA is a relatively inactive compound compared with lipid A derived from Escherichia coli (LPS) and has been demonstrated to act as a partial agonist of LPS-induced inflammation. To assess the potential stimulatory effect of RsDPLA in relation to LPS, we incubated THP-1 cells with RsDPLA (0.001-100 micrograms/ml), LPS (0.02 microgram endotoxin activity/ml), or corn dust extract (CDE; 0.02 microgram endotoxin activity/ml). Incubation with RsDPLA revealed a tumor necrosis factor (TNF)-alpha stimulatory effect at 100 micrograms/ml. In contrast, incubation with LPS or CDE resulted in TNF-alpha release at 0.02 microgram/ml. Pretreatment of THP-1 cells with varying concentrations of RsDPLA before incubation with LPS or CDE (0.02 microgram endotoxin activity/ml) resulted in a dose-dependent reduction in the LPS- or CDE-induced release of TNF-alpha with concentrations of RsDPLA of up to 10 micrograms/ml but not at 100 micrograms/ml. To further understand the role of endotoxin in grain dust-induced airway inflammation, we utilized the unique LPS inhibitory property of RsDPLA to determine the inflammatory response to inhaled CDE in mice in the presence of RsDPLA. Ten micrograms of RsDPLA intratracheally did not cause a significant inflammatory response compared with intratracheal saline. However, pretreatment of mice with 10 micrograms of RsDPLA intratracheally before exposure to CDE (5.4 and 0.2 micrograms/m3) or LPS (7.2 and 0.28 micrograms/m3) resulted in significant reductions in the lung lavage concentrations of total cells, neutrophils, and specific proinflammatory cytokines compared with mice pretreated with sterile saline. These results confirm the LPS-inhibitory effect of RsDPLA and support the role of endotoxin as the principal agent in grain dust causing airway inflammation.

Animals↗
PubMed1998

The effect of of glucocorticoids on grain dust-induced airway disease.

STUDY OBJECTIVES: To determine the effect of glucocorticoids on grain dust-induced airflow obstruction and airway inflammation. DESIGN: Randomized controlled trial. SETTING: University hospital. PARTICIPANTS: Health volunteers. INTERVENTIONS: Two randomized, placebo-controlled trials, each studying 10 healthy volunteers who were pretreated with either triamcinolone acetonide (Azmacort) oral inhaler 4 puffs twice daily (800 microg daily) for 7 consecutive days or IV hydrocortisone (3 microg/kg/min) as a 14-h continuous infusion, then subjected to a controlled inhalation exposure to corn dust extract (CDE) (endotoxin exposure dose of 3 microg/kg). A single-blind, crossover study design was performed for each trial enrolling 10 healthy, lifetime nonsmokers, with no history of lung disease or environmental exposure to grain dust. MEASUREMENTS AND RESULTS: Following each inhalation exposure to CDE, spirometry was performed at regular intervals and BAL was performed at 4 h. Both treatment and placebo groups demonstrated significant decrements in spirometry and increments in BAL cellularity following CDE inhalation compared with placebo. Inhaled steroid treatment resulted in a significantly higher FEV1 only at the 2-h time point following CDE inhalation with no significant differences observed in the BAL total cell concentration or cellular differential compared with placebo. IV hydrocortisone treatment resulted in a significantly higher FEV1 and FVC between 2 and 4 h after CDE inhalation, as well as significant reductions in the BAL total cell, macrophage, and eosinophil concentrations. Interestingly, the concentration of tumor necrosis factor-alpha and interleukin-8 in the BAL fluid was also decreased following treatment with IV glucocorticoids. CONCLUSIONS: These results demonstrate that glucocorticoids, administered IV and perhaps by inhalation, have a mildly protective effect on airflow obstruction and airway inflammation induced by inhalation of grain dust.

Administration, Inhalation↗