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Biomedical subjects

C Ring

Publications and source records attributed to C Ring.

At least 55 records · Page 3Linked to original sources
PubMed1994

Cardiac stimulus intensity and heartbeat detection: effects of tilt-induced changes in stroke volume.

The effects of variations in stroke volume on the intensity of cardiac stimuli was examined in a series of three experiments that employed classical psychophysical methods to assess heartbeat detection. Stroke volume was manipulated by passive body tilt and recorded using impedance cardiography while subjects performed heartbeat detection tasks. The postural manipulation generated little or no change in contractility or momentum but did produce substantial changes in stroke volume. However, this potential source of variation in cardiac stimulus magnitude did not influence either the precision of heartbeat detection or the temporal location of heartbeat sensations. It is concluded that the intensity dimension of the heartbeat stimulus is not determined by stroke volume.

Adolescent↗
PubMed1993

A method of constant stimuli for examining heartbeat detection: comparison with the Brener-Kluvitse and Whitehead methods.

A method of constant stimuli (MCS) for measuring heartbeat detection was examined by comparing performance on this method with the Brener and Kluvitse (BK) method and a variant of the Whitehead (WH') method. All methods required subjects to judge the simultaneity of heartbeat sensations and tones, and each yielded measures of judgment precision and of the temporal location of heartbeat sensations relative to the electrocardiogram R-wave. Both measures were found to be significantly correlated across tasks. A greater proportion of subjects met criteria for classification as heartbeat detectors on the MCS (54%) and BK (50%) tasks than on the WH' task (33%). In the MCS and BK tasks, subjects judged tones presented 100-300 ms after the R-wave to be most simultaneous with heartbeat sensations. Intratask correlations showed that only the MCS procedure yielded stable measurements of both judgment precision and temporal location. The MCS procedure possesses commendable psychometric properties and provides a simpler means than the BK procedure of examining heartbeat detection.

Adult↗
PubMed1992

Hepatitis C viraemia rebound after "successful" interferon therapy in patients with chronic non-A, non-B hepatitis.

A quantitative polymerase chain reaction (PCR) assay for hepatitis C viral RNA (HCV-RNA) was used to monitor viraemia levels in six patients at multiple time points before, during, and after interferon therapy for chronic non-A, non-B hepatitis (NANBH). Prior to therapy, serum HCV-RNA was detected in all patients at approximately 10(4)-10(5) HCV genomes/ml. HCV viraemia became undetectable within 1 month of commencing interferon in three of the five patients whose alanine aminotransferase (ALT) levels decreased to normal on therapy. In the remaining two responder patients, viraemia levels declined more slowly, becoming undetectable after a period of several months. Recurrence of viraemia during therapy was observed in two cases. The one patient whose serum ALT levels remained elevated throughout therapy showed no decline in viraemia. On stopping interferon after a 6 months course, HCV genome titres climbed rapidly in all patients, reaching higher levels than had been observed prior to therapy. Biochemical relapse occurred within 7 months of ending interferon treatment in all but one of the patients who demonstrated this viraemia "rebound" phenomenon.

Adult↗
PubMed1992

Hepatitis C viraemia in United Kingdom blood donors. A multicentre study.

Of 10,633 blood donations tested in three regional blood transfusion centres with two commercial first generation screening assays for antibodies to the hepatitis C virus (HCV), 65 (0.61%) were found to be repeatedly reactive in one or both assays. Five of the 65 were confirmed positive by recombinant immunoblot assay (Ortho RIBA-2) and a further 4 were judged indeterminate. All 5 RIBA-2 positive donations and 1 of the 4 RIBA-2 indeterminates were shown to be viraemic by HCV-RNA polymerase chain reaction (PCR) assays performed at three independent reference laboratories. The remaining 56 screen test reactive donations proved negative by RIBA-2 and, with 1 exception, negative by PCR. We conclude that while first generation anti-HCV screening assays generate a high proportion of false reactions when screening low prevalence populations, results of the RIBA-2 confirmatory test correlate well with PCR findings and thus indirectly with both hepatitis C viraemia and infectivity.

Base Sequence↗
PubMed1992

The temporal locations of heartbeat sensations.

This experiment examined individual differences in the temporal location of heartbeat sensations and the reliability of their detection. Following practice on a familiarization task in judging light-tone simultaneity, 50 subjects were studied for two sessions on a heartbeat detection task, which required judging the simultaneity of heartbeat sensations and tones presented at six intervals following the onset of ventricular contraction. Subjects inspected the heartbeat-tone intervals as frequently and for as long as desired before choosing the one in which heartbeat sensations and tones were most simultaneous. The temporal locations of heartbeat sensations in subjects classified as "good heartbeat perceivers" (n = 16) ranged from 131 and 363 ms following ventricular contraction (mean = 228 ms). Correlations between the familiarization and heartbeat detection tasks in the accuracy of simultaneity judgments and in the frequency and duration of interval inspections suggest that general perceptual abilities and strategies may underlie success in detecting heartbeat sensations.

Adult↗
PubMed1992

[Environmental and food hygiene aspects of cestode infections of humans].

Cysticercus bovis s. inermis, the larvae phase of Taenia saginata is still widely spread. Many reasons are at the origin thereof, e.g. incomplete destruction of the eggs of Taenia saginata during the waste water purification process and differing meat inspection practises. In an area with the same environmental and animal breeding and fattening conditions a yearly average of 6.49% infestation is found in one slaughterhouse, whilst the yearly average in a neighbouring slaughterhouse is 0.93%. The masseter muscles are the main site of infestation. The meat inspection legislation contributes to the infestation with tape-worms in man because of the weakening of the official inspection procedures.

Animals↗
PubMed1991

Effect of alpha-interferon therapy on hepatitis C viraemia in community-acquired chronic non-A, non-B hepatitis: a quantitative polymerase chain reaction study.

Sera from 30 patients with community-acquired, biopsy-proven chronic non-a,non-B hepatitis (NANBH) were tested for antibodies to the C100 protein of hepatitis C virus (HCV). The 20 patients who showed reactivity in this assay were followed prospectively for 6 months, during which time seven were treated with recombinant alpha-interferon. HCV RNA was detected by "nested" polymerase chain reaction (PCR) in 19 of the 20 anti-C100-positive sera taken at the onset of the study and also in five of the ten anti-C100-negative sera. Pretreatment viraemia levels ranged from 2 x 10(3) to 2 x 10(8) HCV genomes/ml. After 6 months of interferon, elevated serum alanine aminotransferase (ALT) levels had fallen to normal in four of the seven treated patients. In each case the response to interferon was accompanied by either a disappearance of or a decline (1 log to 8 log reduction) in viraemia. HCV genome titres in the three nonresponders and in the 13 untreated anti-C100-positive patients did not change significantly over this 6 month period. These findings confirm the aetiological role of HCV in community-acquired NANBH and suggest that quantitative PCR will become a valuable technique for monitoring the antiviral effect of interferon and other experimental treatments.

Adult↗
PubMed1991

Hepatitis C viraemia in adults with type 2 autoimmune hepatitis.

Sera from 14 patients with type 2 autoimmune hepatitis (anti-LKM1 positive) were investigated for evidence of hepatitis C virus (HCV) infection. Antibodies to HCV were detected in 13 patients by both commercial and "in-house" ELISAs and also by a second generation recombinant immunoblot assay. Nine of the 13 (69%) anti-HCV positive patients were shown to be viraemic by a polymerase chain reaction-based assay for serum HCV RNA. Neither anti-HCV nor serum HCV RNA were detected in any of 6 controls with primary biliary cirrhosis or in 39 healthy blood donors. These findings strongly suggest a role for HCV in the pathogenesis of type 2 autoimmune hepatitis.

Adolescent↗
PubMed1991

Hepatitis C antibody profile and viraemia prevalence in adults with severe haemophilia.

Sera from 21 patients who had received large amounts of unheated factor VIII concentrate were tested for antibodies to the hepatitis C virus (HCV) by both commercial (Ortho C100) and 'in house' ELISAs. 'In house' assays utilized recombinant structural (core) or non-structural (replicase) HCV proteins generated by a baculovirus expression system. Antibodies to HCV were detected in 100% of the sera by the core protein based ELISA but in only 62% and 19% by the C100 and replicase based ELISAs, respectively. Hepatitis C viraemia was demonstrated in 90% of the patients by in vitro amplification of the 5' non-coding region of the HCV genome. Amplification with primer sets from two other regions of the genome proved less efficient at detecting viraemia. We conclude that the prevalence of hepatitis C infection in haemophiliacs may have been underestimated previously and that almost all HCV-infected patients have evidence of on-going viral replication.

Adult↗
PubMed1989

[The economic value of a protective vaccination against enzootic bronchopneumonia of cattle].

The bovine enzootic bronchopneumonia is a multi-causal determined and by several factors triggered general factor-disease. Since therapy is mostly disappointing, prophylaxis is the most advantageous way to curb the disease. Vaccination with combined vaccines has been very promising. A cost-benefit-analysis shows that the decrease in morbidity from 72% to 7.3% and in mortality from 5.1 to 0.9% results in a benefit-cost-relation between 5 to 1 and 7 to 1. That means preventive vaccination against crowding associated enzootic bronchopneumonia saves approximately 180,- DM per animal and 250,- DM per animal in case of seasonal enzootic bronchopneumonia.

Animals↗
PubMed1989

Comparison of 3H-misonidazole binding between CHO and 9L cells using the sandwich system.

3H-misonidazole binding of 9L cells was compared with that of CHO cells using an in vitro tumor analog, the sandwich system. In sandwiches there is a gradient of microenvironments, with cells adjacent to the necrotic center subjected to low concentrations of oxygen and glucose and to high concentrations of metabolites. Mixed sandwiches, having 9L and CHO cells interspersed, were used along with sandwiches of each individual cell line. MISO binding was assessed in situ, using autoradiography. Grains per cell were counted and detailed statistics were obtained on the variation in MISO binding among cells located in the same microenvironment. In all cases binding in the regions near the necrotic center was more than 50 times the binding found at the sandwich edge and found in control monolayers, indicating radiobiological hypoxia near the necrotic center. 9L cells began to significantly increase binding of MISO metabolites at a somewhat higher oxygen concentration than did CHO cells. At all oxygen tensions, average per cell binding of the 9L cells was 3 times or more that of the CHO cells, a factor greater than can be explained by the ratio of cell volumes alone. Statistical analyses of the variation in binding among cells in a given microenvironment give some evidence that in the mixed CHO/9L sandwiches there are interactions between the cells of the two different lines which affect the growth patterns of the cells. No preferred binding of misonidazole in the nucleus or cytoplasm was noted within the cells.

Animals↗
PubMed1989

The effect of visual deprivation and proprioceptive change on postural sway in healthy adults.

In 39 healthy active people aged 17 to 79 who had not fallen, anteroposterior sway during quiet standing increased slightly with age; there was no increase with age in lateral sway. Sway increased on deprivation of visual information and altered proprioception due to foot pressure sensory change in all age groups, and especially when both forms of sensation were altered concurrently; but the increase of sway on pressure sensory change was no greater in the older than in the younger subjects.

Adolescent↗
PubMed1989

[CO2-stunning of swine for slaughter from the anesthesiological viewpoint].

For investigations of CO2-stunning of feeder- and slaughter-pigs parameters of behaviour, blood-gas-analyses and electroencephalograms were chosen. The following results were obtained: 1. Blood-gas-analyses proved that the CO2-stunning does not produce unconsciousness due to a lack of oxygen. 2. The criterias of general anaesthesia: unconsciousness, muscle-relaxation and analgesia with total reversibility could be confirmed. 3. The violent convulsive symptoms were evaluated as reactions identical with the stage II of GUEDEL's scheme of anaesthesia. 4. Muscular agitation, which sometimes appeared a few seconds before the stage of excitation, was judged to belong either to the start of the excitation phase or to the end of Guedel's stage of analgesia, during which the sensitivity is decreased. Neither study of behavior nor objective measurements showed, during the first 10 to 20 seconds of exposure to the CO2, any sign of pain or suffering related to the Act for Prevention of Cruelty to Animals, and accordingly such suffering should not be ascribed to the CO2 stunning method.

Abattoirs↗