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Biomedical subjects

C Ring

Publications and source records attributed to C Ring.

At least 37 records · Page 2Linked to original sources
PubMed2000

Contributions of local and central sensations to the perception of exertion during cycling: effects of work rate and cadence.

There is evidence to suggest that perception of exertion during exercise is based on both local and central sensations. The aim of the present experiment was to determine the relative contributions of different sensations to overall perceived exertion during cycling. Eighteen trained cyclists pedalled on a cycle ergometer for 4 min at each of three work rates (100, 150 and 200 W) and cadences (50, 70 and 90 rev x min(-1)). At the end of each bout, they used Borg's category-ratio (CR-10) scale to rate their overall perceived exertion, leg muscle pain, knee pain, breathlessness and heart beat intensity. The results indicated that cadence only influenced local sensations (muscle pain and knee pain), which were significantly higher at slower pedalling rates. Neither overall perceived exertion nor central sensations (breathlessness and heart beat intensity) were significantly affected by cadence. In contrast, increases in work rate were associated with higher ratings for all sensations. Further analyses revealed that variations in these overall ratings of perceived exertion as a function of work rate were accounted for by variations in ratings of muscle pain and breathlessness. The general implication is that perceived exertion during cycling derives from a combination of muscle and respiratory sensations.

Adult↗
PubMed2000

Do depression and anxiety predict recurrent coronary events 12 months after myocardial infarction?

We examined the association between depression and anxiety and recurrent coronary heart disease events during the first 12 months subsequent to myocardial infarction. The Beck Depression Inventory and the State-Trait Anxiety Inventory were completed during hospitalization by 288 myocardial infarction patients. Peel Index score and Killip class were used as indices of disease severity. The 12-month incidence of recurrent coronary heart disease events (fatal and non-fatal) was determined. Eighty-two patients experienced recurrent coronary heart disease events, including 27 cardiac fatalities, during follow-up. Whereas the Peel Index differentiated patients who experienced recurrent events from those who did not (OR 3.00, 95% CI 1.46-6.20), symptoms of depression (OR 0.97, 95% CI 0. 55-1.70) and anxiety (OR 1.00, 95% CI 0.98-1.02) were unrelated to outcome. Depression and anxiety did not predict subsequent coronary heart disease events and were not associated with either Peel Index scores or Killip class.

Anxiety↗
PubMed2000

Secretory immunoglobulin A and cardiovascular reactions to mental arithmetic, cold pressor, and exercise: effects of alpha-adrenergic blockade.

The mechanism underlying acute changes in secretory immunoglobulin A (sIgA) remains to be determined. In this experiment, sIgA and cardiovascular activity were monitored at rest and while participants performed a mental arithmetic task, cold pressor, and submaximal cycle exercise following placebo or 1 mg of the alpha-adrenergic blocker, doxazosin. Under placebo, the tasks produced patterns of cardiovascular activity indicative of combined alpha- and beta-adrenergic, alpha-adrenergic, and beta-adrenergic activation, respectively. Doxazosin was associated with reduced blood pressure during cold pressor, but not during arithmetic or exercise. Mental arithmetic elicited increases in sIgA concentration and exercise produced increases in both sIgA concentration and secretion rate; these changes were unaffected by alpha blockade. In contrast, the cold pressor was associated with decreases in both sIgA concentration and secretion rate, which were blocked by doxazosin. These data suggest that acute decreases, but not increases, in sIgA are mediated by alpha-adrenergic mechanisms.

Adrenergic alpha-Antagonists↗
PubMed1999

Prevalence of Campylobacter spp. in poultry and poultry meat in Germany.

Of 509 samples from poultry flocks, 209 isolates (41.1%) were Campylobacter positive. The number of positive cases in broiler carcasses was 45.9%. Of 52 pheasants investigated, 25.9% were Campylobacter positive. Campylobacter jejuni was isolated from 86 (42.0%) poultry flock samples, 47 (43%) broiler samples and 15 (28%) wild pheasant samples. C. coli was found at a rate of 1.2% in poultry flocks, 13% in broilers and 21% in pheasants.

Animals↗
PubMed1999

Secretory immunoglobulin A and cardiovascular reactions to mental arithmetic, cold pressor, and exercise: effects of beta-adrenergic blockade.

We investigated the influence of sympathetic nervous system processes on mucosal immunity by comparing the effects of beta-adrenoceptor blockade with 40 mg propranolol and placebo on secretory immunoglobulin A (sIgA) at rest and during paced serial arithmetic, cold pressor, and submaximal cycling. These tasks produced patterns of cardiovascular activity indicative of combined alpha- and beta-adrenergic, alpha-adrenergic, and beta-adrenergic activation, respectively. The effectiveness of the beta blockade was confirmed by the attenuation under propranolol of the shortening of the cardiac preejection period and the tachycardia elicited by mental arithmetic and exercise. The cold pressor test did not affect sIgA under either the placebo or the propranolol. Mental arithmetic increased sIgA concentration, and this increase was not blocked by propranolol. Exercise elicited increases in both sIgA concentration and sIgA secretion rate, which were not diminished by beta blockade. These data suggest that sIgA is not regulated by beta-adrenergic mechanisms.

Adrenergic beta-Antagonists↗
PubMed1999

Secretory immunoglobulin A and cardiovascular activity during mental arithmetic and paced breathing.

The role of the autonomic nervous system in secretory immunoglobulin A (sIgA) responses to laboratory challenge was explored in a study in which sIgA and cardiovascular activity were recorded at rest and during mental arithmetic and paced breathing. These tasks were selected to preferentially engage the sympathetic and parasympathetic nervous systems, respectively. Mental arithmetic elicited a mixed pattern of increased alpha- and beta-adrenergic activity and a reduction in parasympathetic activity; diastolic blood pressure, total peripheral resistance, and systolic blood pressure increased, preejection period shortened, and heart rate variability decreased. In contrast, paced breathing primarily elicited an increase in parasympathetic activity; heart rate variability increased. Mental arithmetic also provoked an increase in sIgA concentration but no change in saliva volume, whereas paced breathing affected neither sIgA concentration nor saliva volume. These data suggest that sIgA responses to laboratory challenges are mediated by sympathetic rather than parasympathetic processes.

Adult↗
PubMed1998

Endogenous monoamine oxidase A inhibitory activity (tribulin), measured in saliva, is related to cardiovascular reactivity in normal individuals.

Salivary monoamine oxidase A inhibitory activity (MAO-AI), mean arterial blood pressure (MAP) and heart rate (HR) were determined simultaneously in healthy male students (n = 13) at rest, before a mild psychological stressor, twice during the task and 18 minutes after the end of the task. The sample as a whole showed significant differences in MAP and HR across occasions (respectively, p < 0.001 for both). Salivary MAO-AI could distinguish novice and experienced game players (p < 0.02) and was consistently positively correlated with MAP (r = 0.58, p < 0.05 on occasion 2). Pre-task measures of MAO-AI for an increased sample (n = 18) were associated with higher MAP (but not HR) throughout the experiment (p < 0.05). Those subject with falling MAO-AI profiles from task to recovery showed significantly greater simultaneous decline in HR than those with a rising MAO-AI profile (p < 0.05).

Adult↗
PubMed1998

A test of the validity of the method of constant stimuli as an index of heartbeat detection.

A heartbeat detection task, based on the method of constant stimuli (MCS), requires participants to judge which of a series of tones presented at different delays following a heartbeat are coincident with the heartbeat. Two experiments were conducted to test the validity of the MCS in assessing individual differences in the ability to detect heartbeat sensations. The first experiment found the MCS to be valid, in that about one-third of subjects met the criterion for classification as heartbeat detectors when the tones were presented with respect to their actual heartbeats, but only one subject met the criterion when the tones were presented with respect to previously recorded heartbeats. The second experiment manipulated the timing of the comparison intervals (i.e., R + 100-600 ms rather than R + 0-500 ms) to examine the validity of the median R-wave to tone interval as an index of temporal location of perceived heartbeats, and found it to be a valid index.

Acoustic Stimulation↗
PubMed1998

[Campylobacter spp. in the surroundings of poultry meat production-- incidence and chinolone resistance].

The incidence of Campylobacter in poultry meat production and in poultry meat gives cause for increasing concern in this field. Results of studies about clinical cases of Campylobacter in humans show a growing tendency. With poultry and foal mainly C. jejuni and C. coli are isolated, while C. jejuni has been identified as one of the most frequent bacterial pathogens of enteritis in humans also. Of altogether 509 samples from poultry herds, 209 isolates (41.1%) were Campylobacter positive. Tests in slaughter-houses showed that there are various factors that influence the contamination of the carcass during the process of slaughtering. The number of positive cases with chicken carcass is about 45.9% which is higher than with the animals, flocks. Of 52 pheasants 25.9% were Campylobacter positive. During the last 3 years Campylobacter isolates showed a growing Chinolone resistance (19.14% in butchered roast chicken and 28.5% in pheasants.

Abattoirs↗
PubMed1998

Secretory immunoglobulin A and cardiovascular reactions to mental arithmetic and cold pressor.

Secretory immunoglobulin A (sIgA) in saliva and cardiovascular reactions to mental arithmetic and cold pressor tasks were recorded in 16 healthy young men on two sessions, 4 weeks apart. Both tasks elicited significant increases in sIgA secretion rate, reflecting increases in both salivary volume and sIgA concentration. Whereas mental arithmetic elicited a mixed pattern of alpha- and beta-adrenergic cardiovascular reactions, the pattern of reactions to cold pressor was predominantly alpha-adrenergic. Task levels of sIgA secretion rate, sIgA concentration, and saliva volume showed moderate to high test-retest reliability (r = .52-.83), although test-retest correlations were less impressive for change scores (r = -.19-.53). The pattern of correlations between change in sIgA secretion rate and cardiovascular reactivity variables was inconsistent.

Adult↗
PubMed1997

Sensitivity to mechanical stimuli and the role of general sensory and perceptual processes in heartbeat detection.

Sensitivity to heartbeat sensations is commonly assessed using tasks that require individuals to judge the simultaneity of heartbeats and tones. In two experiments, we investigated the suitability of this paradigm for examining cardioception. In the first experiment, participants judged the simultaneity of near-threshold vibrations and suprathreshold tones. Precision in judging vibration-tone simultaneity was directly related to the detectability of the mechanical stimuli, thereby supporting use of the simultaneity paradigm to assess heartbeat detection. In the second experiment, we examined the influences of sensitivity to mechanical stimuli and the ability to make intermodality simultaneity judgments on the precision of heartbeat detection. We measured participants' vibrotactile thresholds, precision in judging light-tone simultaneity, and precision in judging heartbeat-tone simultaneity. The ability to judge the simultaneity of lights and tones accounted for 24.3% of the variance in precision of heartbeat detection, and mechanical sensitivity accounted for a further 8.5%.

Adolescent↗
PubMed1996

Expression pattern of collagen IX and potential role in the segmentation of the peripheral nervous system.

Segmentation of the peripheral nervous system of vertebrates requires guidance cues located in the adjacent somitic mesoderm. Recent experiments suggest that inhibitory molecules in the posterior somite may influence segmentation by restricting the outgrowth of axons and the migration of neural crest cells to the anterior somite. A potential candidate for an inhibitory molecule is collagen IX, a chondroitin sulfate proteoglycan made by sclerotome cells of the somite and by the notochord. Immunohistochemical localization of collagen IX demonstrated that its expression in the posterior sclerotome of the somite correlates with axon outgrowth and neural crest cell migration through the anterior sclerotome. In vitro, sensory neurites on fibronectin, and motor neurites on basal lamina extract, avoid regions which contain substrate-bound collagen IX. This effect can be abolished by chondroitinase treatment, suggesting that the glycosaminoglycan component of the molecule is responsible for this activity. Further, collagen IX elicits a similar avoidance behavior by neural crest cells in vitro. These data suggest that collagen IX contributes to the segmentation of the peripheral nervous system in vivo.

Animals↗
PubMed1996

Influence of beliefs about heart rate and actual heart rate on heartbeat counting.

The heartbeat counting task is used widely to assess the ability to perceive cardiac sensations. However, performance on this task may be determined by processes other than sensitivity to cardiac stimuli. Beliefs about the effects of postural and exercise challenges on heart rate were assessed by questionnaire prior to performing the heartbeat counting task, and then actual heart rate was manipulated during the counting task by changes in posture and exercise. On average, counted heart rates were closer to beliefs about heart rate than to actual heart rate. Hierarchical multiple regression analyses indicated that (a) believed heart rates predicted counted heart rates while controlling for actual heart rates and (b) actual heart rates also predicted counted heart rate while controlling for heart rate beliefs. These data suggest that the rate of heartbeat counting is influenced by beliefs about heart rate and by the processing of cardiac sensations.

Adult↗
PubMed1996

Secretory immunoglobulin A and cardiovascular responses to acute psychological challenge.

Cardiovascular activity and secretory immunoglobulin A (sIgA) in saliva were recorded at rest, during a 30-min computer game task, and during subsequent recovery. Blood pressure (BP) rose and remained elevated during the task and returned to resting levels during recovery. This pressor response was produced by increased total peripheral resistance rather than increased cardiac output. SIgA secretion rate also increased during the task, although the effect proved significant only toward the end of the task. As such, the data provide preliminary indication that sIgA is sensitive to acute psychological challenge in the laboratory. Although correlational analyses revealed that sIgA reactions were stable, they were not significantly correlated with pressor reactions. The influence of task uncertainty was explored by comparing individuals who had previously played the computer game with those who had not. Task-induced increases in BP and sIgA were a feature of individuals new to the computer game. In contrast to these novice players, experienced players showed minimal increases in BP and no increases in sIgA.

Journal Article↗
PubMed1996

EU experimental study on wild boar trichinellosis.

From January 1994 onwards the Council Directive 92/45 EEC concerning the examination of wild game meat for trichinellosis is valid. Laboratory methods required are identical to those used for the examination of pork. In an international experiment the suitability of these methods to control wild boar meat was tested. Required meat parts of experimentally with T. spiralis infected wild boars were shipped to seven laboratories in Europe under code. It was concluded that trichinoscopy and pool sample digestion methods meant for pork examination could equally well be used for control of wild boar meat. The so called Trichomatic method required a few adaptations. Moreover it was demonstrated that extra washing procedures were required to prevent cross contamination between samples with Trichomatic equipment.

Animals↗
PubMed1995

Two chondroitin sulfate proteoglycans differentially expressed in the developing chick visual system.

Two monoclonal antibodies, 2B9 and 9BA12, were used to identify and characterize two different chondroitin sulfate proteoglycans (CSPGs) associated with the embryonic chick visual system. Monoclonal antibody 2B9 recognizes a carbohydrate epitope of collagen type IX proteoglycan. Immunohistochemistry showed that collagen type IX proteoglycan was abundant in the vitreous body and meninges, but absent in brain and retina. In developing trunk regions, collagen type IX proteoglycan is segmentally distributed in the somites, appearing only in the posterior sclerotome. Monoclonal antibody 9BA12 recognizes collagen type IX proteoglycan from vitreous body and an unidentified chondroitin sulfate proteoglycan in retina and brain, herein referred to as 9BA12 CSPG. Immunohistochemistry showed that 9BA12 CSPG is present in the optic fiber layer of the retina, coinciding temporally and spatially with the onset and cessation of ganglion cell axon growth. In the trunk region, 9BA12 immunostaining appears in the developing spinal cord and throughout the sclerotome. In culture, neither the collagen type IX proteoglycan nor the brain-derived 9BA12 CSPG were able to support neurite outgrowth from retinal ganglion cell explants. In combination with basal lamina proteins, collagen type IX proteoglycan slightly inhibited neurite outgrowth and led to a stronger fasciculation of retinal axons. In contrast, 9BA12 CSPG had no inhibitory effect on the outgrowth of retinal axons and had no effect on their fasciculation. Our study demonstrates the existence of two chondroitin sulfate proteoglycans in the developing visual system of the chick. Based on the developmental expression and the results from neurite outgrowth experiments, it was concluded that the 9BA12 CSPG does not operate as a neurite outgrowth inhibitor for retinal axons.

Animals↗
PubMed1994

Effects of data limitations on heartbeat detection in the method of constant stimuli.

In the method of constant stimuli applied to measuring heartbeat detection, subjects judge the simultaneity of heartbeats and exteroceptive comparison stimuli presented at various intervals after the R-wave (0, 100, 200, 300, 400, and 500 ms). Using versions of this procedure, investigators have found that between 20% (Yates, Jones, Marie, & Hogben, 1985) and 54% (Brener, Liu, & Ring, 1993) of subjects can detect heartbeat sensations. Whereas Yates et al. used a single comparison stimulus on each trial and Brener et al. used 10, the present study examined whether this disparity in heartbeat detection performance could be attributed to the number of comparison stimuli presented on each trial. In each of 360 trials, 30 subjects judged the simultaneity of heartbeat sensations and tones following 1, 5, or 10 comparison stimulus presentations. Significantly fewer subjects met the criterion for heartbeat detection with 1 tone presentation (13%) than with either 5 (43%) or 10 (47%) tone presentations. It is concluded that a single stimulus presentation imposes data limitations that result in underestimation of the accuracy of heartbeat detection. The presentation of at least 5 stimuli in each trial alleviates this limitation.

Adolescent↗