Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “cycle threshold value”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 739 records · Page 41Linked to original sources
PubMed1984

Sensitivity of maximal aerobic power to training is genotype-dependent.

Ten pairs of monozygotic twins of both sexes were submitted to a 20-wk endurance-training program, four and five times per week, 40 min per session, at an average of 80% of the maximal heart rate reserve. Testing and training were performed on cycle ergometers. Maximal aerobic power (MAP in ml O2 X min-1 X kg-1) and ventilatory aerobic (VAT) and anaerobic (VANT) thresholds (ml O2 X min-1 X kg-1) were measured before and after the training program, as well as during the 7th and 14th week to adjust training to changes in maximal heart rate. Considering the 20 individuals as a group, training significantly (P less than or equal to 0.01) increased MAP (from 44 +/- 6 to 50 +/- 6), VAT (25 +/- 3 to 30 +/- 4), and VANT (36 +/- 5 to 42 +/- 6). Thus, MAP improved by 12% of the pre-test value, while mean changes in VAT and VANT reached 20% and 17%, respectively. There were, however, considerable interindividual differences in training gains as exemplified by a range of about 0% to 41% for MAP. Differences in the MAP response to training were not distributed randomly among the twin pairs. Thus, intraclass correlations computed with the amount of improvement in MAP (ml O2 X min-1 X kg-1) reached 0.74 (P less than 0.01) indicating that members of the same twin-pair yielded approximately the same response to training. The same coefficient reached 0.43 and 0.24 for VAT and VANT, respectively (P greater than 0.05). These results suggest that there are considerable individual differences in the adaptive capacity to short-term endurance training. Moreover, sensitivity of maximal aerobic power to such training is largely genotype-dependent.

Adolescent↗
PubMed2005

Effect of endurance training on different mechanical efficiency indices during submaximal cycling in subjects unaccustomed to cycling.

The purpose of this study was to evaluate different efficiency indices, i.e., gross (GE: no baseline correction), net (NE: resting metabolism as baseline correction), and work (WE: unloaded exercise as baseline correction), to reveal the effect of endurance training on mechanical efficiency. Nine healthy sedentary women undertook an incremental test and submaximal cycling exercise, at an intensity corresponding to 50% of the pretraining peak oxygen uptake, before and after 6 weeks of endurance training (18 sessions of 45 min). The training effects on efficiency indices were tested by comparisons based on GE, NE, and WE as well as by the differences between the percentage changes of all indices (%GE, %NE, %WE). Endurance training resulted in significantly higher GE (+11.1%; p < 0.001) and NE (+9.1%; p < 0.01). Only minor significant improvement (+2.4%; p < 0.05) was observed with the WE index because the value used for baseline subtraction was significantly reduced by the training sessions, due perhaps to improvement in pedaling skill. As a consequence, %WE was significantly lower than %GE (p < 0.01) and %NE (p < 0.05), while %GE and %NE were not significantly different. We conclude that mechanical efficiency of cycling increases with training in women previously unfamiliar with cycling, and that the WE index is less sensitive to this training effect than GE and NE indices.

Adult↗
PubMed1993

Electrocardiogram signal variance analysis in the diagnosis of coronary artery disease--a comparison with exercise stress test in an angiographically documented high prevalence population.

Variance electrocardiography (variance ECG) is a new resting procedure for detection of coronary artery disease (CAD). The method measures variability in the electrical expression of the depolarization phase induced by this disease. The time-domain analysis is performed on 220 cardiac cycles using high-fidelity ECG signals from 24 leads, and the phase-locked temporal electrical heterogeneity is expressed as a nondimensional CAD index (CAD-I) with the values of 0-150. This study compares the diagnostic efficiency of variance ECG and exercise stress test in a high prevalence population. A total of 199 symptomatic patients evaluated with coronary angiography was subjected to variance ECG and exercise test on a bicycle ergometer as a continuous ramp. The discriminant accuracy of the two methods was assessed employing the receiver operating characteristic curves constructed by successive consideration of several CAD-I cutpoint values and various threshold criteria based on ST-segment depression exclusively or in combination with exertional chest pain. Of these patients, 175 with CAD (> or = 50% luminal stenosis in 1 + major epicardial arteries) presented a mean CAD-I of 88 +/- 22, compared with 70 +/- 21 in 24 nonaffected patients (p < 0.01). Variance ECG provided a stochastically significant discrimination (p < 0.01) which was matched by exercise test only when chest pain variable was added to ST-segment depression as a discriminating criterion. Even then, the exercise test diagnosed single-vessel disease with a significantly lower sensitivity. At a cutpoint of CAD-I > or = 70, compared with ST-segment depression > or = 1 mm combined with exertional chest pain, the overall sensitivity of variance ECG was significantly higher (p < 0.01) than that of exercise test (79 vs. 48%). When combined, the two methods identified 93% of coronary angiography positive cases. Variance ECG is an efficient diagnostic method which compares favorably with exercise test for detection of CAD in high prevalence population.

Adult↗
PubMed1980

Aerobic and anaerobic threshold of Japanese male adults.

Aerobic threshold (AerT) and anaerobic threshold (AnT) were determined in 20 non-athletes (physical education majors) and 10 athletes (varsity athletes), aged 20.8-31.5 years, during incremental exercise on the cycle ergometer; workloads were increased by 0.25 Kp every 3 minutes at 50 rpm. AerT was determined using selected respiratory gas exchange parameters, i.e., non-linear increase in VE and VCO2, and peak VO2 . VE-1. AnT was estimated from break-away VE and the onset of decrease in FECO2. The reliability of the testing procedure was studied separately on 24 physical education majors. VO2 max was measured during another incremental exercise on the cycle ergometer. The mean values of VO2 max for non-athletes and athletes were 3.17 l/min (48.1 ml/kg . min) and 3.64 l/min (54.7 ml/kg . min), respectively. The test-retest correlation coefficients were 0.961 for VO2-AerT and 0.786 for VO2-AnT. The mean values of VO2-AerT and %AerT were 1.62 l/min and 51.0% for non-athletes, and 2.23 l/min and 61.9% for athletes. The mean values of VO2-AnT and %AnT were 2.09 l/min and 66.3% for non-athletes, 2.49 l/min and 69.2% for athletes.

Adult↗
PubMed2000

Increased risk of early pregnancy loss by profound suppression of luteinizing hormone during ovarian stimulation in normogonadotrophic women undergoing assisted reproduction.

The impact of suppressed concentrations of circulating luteinizing hormone (LH) during ovarian stimulation on the outcome of in-vitro fertilization or intracytoplasmic sperm injection treatment in 200 consecutive, normogonadotrophic women (couples) was analysed retrospectively. A standard stimulation protocol with mid-luteal gonadotrophin-releasing hormone (GnRH) agonist down-regulation and ovarian stimulation with recombinant follicle stimulating hormone (FSH) was used in all cases. Blood was sampled from each woman on stimulation days 1 and 8 for analysis of oestradiol and LH in serum. A threshold value of serum LH of 0.5 IU/l on stimulation day 8 (S8) was chosen to discriminate between women with low or 'normal' LH concentrations. Low concentrations of LH on S8 (<0.5 IU/l) were found in 49% (98/200) of the women. This group of women was comparable with the normal LH group with regard to pre-treatment clinical parameters, and to the parameters characterizing the stimulation protocol with the exception of serum oestradiol concentration, which on S8 was significantly lower than in the normal LH group (P < 0.001). The proportion of positive pregnancy tests was similar in the two groups (30% versus 34% per started cycle), but the final clinical treatment outcome was significantly different, with a five-fold higher risk of early pregnancy loss (45% versus 9%; P < 0.005) in the low LH group and consequently a significantly poorer chance of delivery than in the normal LH group. It is concluded that a substantial proportion of normogonadotrophic women treated with GnRH agonist down-regulation in combination with FSH, devoid of LH activity, experience LH suppression, which compromises the treatment outcome. Whether these women would benefit from supplementation with recombinant LH or human menopausal gonadotrophin during ovarian stimulation, remains to be proven in the future by prospective randomized trials.

Abortion, Spontaneous↗
PubMed2003

Population dynamics of male-killing and non-male-killing spiroplasmas in Drosophila melanogaster.

The endosymbiotic bacteria Spiroplasma spp. are vertically transmitted through female hosts and are known to cause selective death of male offspring in insects. One strain of spiroplasma, NSRO, causes male killing in Drosophila species, and a non-male-killing variant of NSRO, designated NSRO-A, has been isolated. It is not known why NSRO-A does not kill males. In an attempt to understand the mechanism of male killing, we investigated the population dynamics of NSRO and NSRO-A throughout the developmental course of the laboratory host Drosophila melanogaster by using a quantitative PCR technique. In the early development of the host insect, the titers of NSRO were significantly higher than those of NSRO-A at the first- and second-instar stages, whereas at the egg, third-instar, and pupal stages, the titers of the two spiroplasmas were almost the same. Upon adult emergence, the titers of the two spiroplasmas were similar, around 2 x 10(8) dnaA copy equivalents. However, throughout host aging, the two spiroplasmas showed strikingly different population growth patterns. The titers of NSRO increased exponentially for 3 weeks, attained a peak value of around 4 x 10(9) dnaA copy equivalents per insect, and then decreased. In contrast, the titers of NSRO-A were almost constant throughout the adult portion of the life cycle. In adult females, consequently, the titer of NSRO was significantly higher than the titer of NSRO-A except for a short period just after emergence. Although infection of adult females with NSRO resulted in almost 100% male killing, production of some male offspring was observed within 4 days after emergence when the titers of NSRO were as low as those of NSRO-A. Based on these results, we proposed a threshold density hypothesis for the expression of male killing caused by the spiroplasma. The extents of the bottleneck in the vertical transmission through host generations were estimated to be 5 x 10(-5) for NSRO and 3 x 10(-4) for NSRO-A.

Animals↗
PubMed1988

Comparison of objective methods for determining ventilatory threshold.

This study was undertaken to compare and re-examine the relation of lactate threshold (LT) and ventilatory threshold (VT), using six objective determination methods proposed previously. Twenty-one young male subjects performed a cycle exercise test in which the work rate was increased by 150 kg.m every 2 min up to his limit of volitional fatigue. Through each test, gas exchange parameter measurements were made every 1 min (every 30 s at nearly maximal level), and the venous blood samples were taken from a warmed ear lobe at each work rate for determining blood lactate concentration. LT and its variance were determined by the intersecting straight lines regression. LT ranged from 0.72 to 1.40 l/min in terms of VO2, and the mean value of S.D. for each LT was about 0.1 l/min. Each objective method for determining VT used in this study was based on the simple modelling of the criterion for visual detection of VT, that is the non-linear increase in VE or the systematic increase in VE/VO2. When the relationship between LT and VT was examined, VT by the objective methods based on determining minimum value of VE/VO2 showed relatively high consistency with LT. Of 16-20 individuals out of all 21 subjects, there were VT within LT +/- 0.2 in VO2. It is concluded that VE/VO2 is a more sensitive index for detecting VT than VE in the gas exchange parameters, and the objective VT determination method based on minimum value of VE/VO2 could facilitate estimation of LT within an error of +/- 0.2 l/min VO2 in most normal individuals.

Adult↗
PubMed1994

Heart rate threshold related to lactate turn point and steady-state exercise on a cycle ergometer.

The aim of this study was to investigate heart rate threshold (HRT) related exercise intensities by means of two endurance cycle ergometer tests using blood lactate concentration [La], pulmonary ventilation (VE), oxygen uptake (VO2), heart rate (HR) and electromyogram (EMG) activity of working muscle. Firstly, 16 healthy female students [age, 21.4 (SD 2.8) years; height, 167.1 (SD 5.1) cm; body mass 62.7 (SD 7.1) kg] performed an incremental exercise test (10 W each minute) on an electrically braked cycle ergometer until they felt exhausted. The HRT and lactate turn point (LTP) were assessed by means of computer-aided linear regression break point analysis from the relationship of HR or [La] to power output. No significant difference was found between HRT and LTP for all the variables measured. Secondly, two endurance tests (ET) of 20 min duration were performed by 7 subjects. The first (ET I) was performed at an exercise intensity which was about 10% lower than the power output at HRT [61.2 (SD 3.1)% maximal oxygen uptake (VO2max)], the second (ET II) at an exercise intensity about 10% higher than the power output at HRT [79.2 (SD 3.4) % VO2max]. The parameters measured showed a clear steady state in ET I. All mean values were lower than values at HRT [power, 138.7 (SD 18.9) W; HR, 172.1 (SD 4.7) beats.min-1; VO2, 2.2 (SD 0.3) l.min-1; VE, 54.0 (SD 9.1) l.min-1; [La], 3.7 (SD 1.1) mmol.l-1; EMG, 81.1 (SD 24.0) microV] except HR which was the same.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2002

Determinants of VO(2) kinetics at high power outputs during a ramp exercise protocol.

PURPOSE: To determine the relationship between the additional, nonlinear increase in oxygen uptake (Delta VO(2)) that occurs at high power outputs during a ramp cycle ergometer test, on one hand; and possible explanatory mechanisms of the phenomenon, such as cardiorespiratory work, blood lactate, fitness level, or muscle fiber distribution, on the other. METHODS: Ten healthy, sedentary young adults (age (mean +/- SEM), 22 +/- 1 yr) were chosen as subjects. A muscle biopsy specimen was taken from the vastus lateralis of the right leg to determine fiber type distribution by immunohistochemical identification of myosin heavy chain (MHC) isoforms. During the ramp tests (power output increases of 5 W every 15-s interval), the ventilatory threshold (VT) and lactate threshold (LT) were measured. We defined Delta VO(2) as the difference between "true" VO(2) values observed at the maximal power output (VO(2)obs) and those expected (VO(2)exp) from the previous linear VO2:power output relationship below the VT. RESULTS: A nonlinear increase was observed in VO2 (Delta VO(2) = 239 +/- 79 mL x min(-1), P < 0.05 for VO(2)obs vs VO(2)exp), which was significantly correlated with the percentage of type IIX fibers (r = 0.80, P < 0.05). No other correlations were found between Delta VO(2) and possible explanatory mechanisms. CONCLUSION: A greater percentage of type IIX fibers is associated with a higher excess VO(2) at high power outputs (above VT).

Adult↗
PubMed1993

Determination of lactate threshold by respiratory gas exchange measures and blood lactate levels during incremental load work.

OBJECTIVE: The purpose of this investigation was the determination of the lactate threshold (LT) by selected respiratory gas exchange measures and venous blood lactate levels during incremental load work on a mechanically braked cycle ergometer. DESIGN: Repeated measures design. SETTING: Human Performance Laboratory. PARTICIPANTS: Eight healthy trained soccer players (mean age 21.9 +/- 3.0 yr, mean VO2max = 59.2 +/- 3.6 ml.kg.min-1). OUTCOME MEASURE: Subjects conducted two incremental load work tests. Incremental load work was increased by 1 kilopond (kp) every third minute at 60 rpm until voluntary exhaustion. Blood samples from a forearm vein were collected during the second trial (T2) only and analyzed for lactic acid [LA-]. RESULTS: One-way analysis of variance (ANOVA) with repeated measures indicated no statistically significant difference between the two tests for maximal oxygen uptake (VO2max), maximal carbon dioxide production (VCO2max), maximal heart rate (HRmax), maximal pulmonary ventilation (VEBTPSmax) and lowest ventilatory equivalent of oxygen (VE/VO2), respectively; however, there was a significant difference among the oxygen uptake (VO2) values at the LT for the four determination methods. In our subjects, the measured (mean +/- SD) VE/VO2 in relation to VO2 for the first trial (T1) of 22.9 +/- 1.9 occurred at VO2 of 1.27 +/- 0.8 l.min-1. The lowest VE/VO2 and the onset of [LA-] accumulation calculated from individual exponential equations relating VE to VO2 yielded VO2 values of 1.77 +/- 0.18 and 1.74 +/- 0.25 l.min-1 for the T2. Utilizing natural log for lactate ln [LA-] to natural log for ln (VO2) equations, the LT for T2 occurred at VO2 of 1.30 +/- 0.70 l.min-1. CONCLUSION: LT was best predicted by the measured lowest VE/VO2 and the plot of the ln [LA-] to ln VO2 relationship. The methods used in this study provide a valid estimate of the LT and support the use of measured lowest VE/VO2 as an indirect measure of the LT.

Acidosis, Lactic↗
PubMed2006

Meta-analysis based on control of false discovery rate: combining yeast ChIP-chip datasets.

MOTIVATION: High-throughput microarray technology can be used to examine thousands of features, such as all the genes of an organism, and measure their expression. Two important issues of microarray bioinformatics are first, how to combine the significance values for each feature across experiments with high statistical power, and second, how to control the proportion of false positives. Existing methods address these issues separately, in spite of their linked usage. RESULTS: We present a novel method (ESP) to address the two requirements in an interdependent way. It generalizes the truncated product method of Zaykin et al. to combine only those significance values which clear their respective experiment-specific false discovery restrictive thresholds, thus allowing us to control the false discovery rate (FDR) for the final combined result. Further, we introduce several concepts that together offer FDR control, high power, quality control and speed-up in meta-analysis as done by our algorithm. Computational and statistical methods of research synthesis like the one described here will be increasingly important as additional genome-wide datasets accumulate in databases. We apply our method to combine three well-known ChIP-chip transcription factor binding datasets for budding yeast to identify significant intergenic regulatory sequences for nine cell cycle regulating transcription factors, both with high power and controlled FDR.

Algorithms↗
PubMed1978

Macdonald's model and the transmission of bilharzia.

The paper considers a model for the transmission of bilharzia based on Macdonald's assumptions, in the light of data observed in the field. It is shown, in particular, that the threshold parameter governing whether or not an endemic cycle can be established is closely related to the proportion of infected snails in a community, and that this proportion is normally observed to be rather smaller than is compatible with the model. By considering more sophisticated models, allowing for the latent period of infection in the snails, and also for spatial and seasonal heterogeneity, the effective proportion of infected snails, from the point of view of Macdonald's model, is shown to be rather larger, and expressions are given whereby it can be evaluated from observable quantities. However, for the data from Malirong which are taken as illustration, it is also demonstrated that an even more plausible threshold value is obtained from a simple model incorporating human immunity in addition to the assumptions of Macdonald's model, and that, if this model were reasonable, human immunity would appear to be the most important factor in controlling the level of the disease in Malirong.

Animals↗
PubMed2001

Comparison of the effectiveness of recombinant and urinary FSH preparations in the achievement of follicular selection in chronic anovulation.

In order to compare the effectiveness of urinary and recombinant FSH (rFSH) preparations in achieving the threshold of follicular growth, stimulated cycles from patients with chronic anovulation, treated with a constant dose of FSH until the emergence of a selected follicle, were retrospectively analysed. Sixty-four cycles were performed using a similar starting dose of either urinary FSH (group 1) or rFSH (group 2), which was kept constant up to the time of follicular selection, assessed on ultrasound (follicular diameter >10 mm). The results of this study showed that, while the number of selected follicles was similar, the mean daily FSH dose required to achieve the threshold of follicular selection was significantly lower in group 2 (70.4 +/- 3.4 IU/day) than in group 1 (86.5 +/- 4 IU/day; P < 0.005). Furthermore, at the time of human chorionic gonadotrophin (HCG) administration, the total FSH dose was significantly lower in group 2 than in group 1, but plasma oestradiol values were equivalent. These data suggest that the higher effectiveness of rFSH preparations over urinary ones may be explained by a lower threshold dose required to achieve follicular selection.

Journal Article↗
PubMed2003

EMG signs of neuromuscular fatigue related to the ventilatory threshold during cycling exercise.

We questioned whether electromyographic (EMG) signs of neuromuscular fatigue accompany the changes in respiratory variables measured at the ventilatory threshold (VTh) during exercise on a cycloergometer. This was based on the assumption that the activation of muscle afferents sensitive to accumulation of lactate and potassium is suspected to elicit both the EMG signs of fatigue and hyperventilation. In 39 subjects performing an incremental cycling, the EMG estimates of neuromuscular fatigue in vastus lateralis were a non-linear increase in root mean square (RMS), a decrease in median frequency (MF), a non-linear increase in low-frequency EMG energies (EL), and/or a decrease in high-frequency energies (EH). VTh was determined from a non-linear increase in VCO2 [VTh(VCO2 slope)] and an increased value of the respiratory equivalent for oxygen [VTh(VE/VO2)]. We measured a significant increase in venous blood concentration of lactate and potassium, and a significant pHv fall at VTh. One EMG estimate of fatigue was detected in 33/39 individuals and two EMG estimates in 17 subjects. Highly significant positive correlations were found between the oxygen uptakes corresponding to each EMG estimate and to each detection criterion of VTh. These observations suggest that the activation of muscle sensory pathways contribute to the mechanism of VTh.

Acidosis, Lactic↗
PubMed2004

Sweat lactate response during cycling at 30 degrees C and 18 degrees C WBGT.

Sweat lactate reflects eccrine gland metabolism. However, the metabolic tendencies of eccrine glands in a hot versus thermoneutral environment are not well understood. Sixteen male volunteers completed a maximal cycling trial and two 60-min cycling trials [30 degrees C = 30 +/- 1 degrees C and 18 degrees C = 18 +/- 1 degrees C wet bulb globe temperature (WBGT)]. The participants were requested to maintain a cadence of 60 rev min(-1) with the intensity individualized at approximately 90% of the ventilatory threshold. Sweat samples at 10, 20, 30, 40, 50 and 60 min were analysed for lactate concentration. Sweat rate at 30 degrees C (1380 +/- 325 ml x h(-1)) was significantly greater (P < 0.05) than at 18 degrees C (632 +/- 311 ml x h(-1)). Sweat lactate concentration was significantly greater (P < 0.05) at each time point during the 18 degrees C trial, with values between trials tending to converge across time. During the 30 degrees C trial, both heart rate (20, 30, 40, 50 and 60 min) and rectal temperature (30, 40, 50 and 60 min) were significantly higher than in the 18 degrees C trial. Higher sweat lactate concentrations coupled with lower sweat rates may indicate a greater relative contribution of oxygen-independent metabolism within eccrine glands during exercise at 18 degrees C. Decreases in sweat lactate concentration across time suggest either greater dilution due to greater sweat volume or increased reliance on aerobic metabolism within eccrine glands. The convergence of lactate concentrations between trials may indicate that time-dependent modifications in sweat gland metabolism occur at different rates contingent partially on environmental conditions.

Adult↗
PubMed1995

[Dose intensity in cancer chemotherapy: definition, average relative dose intensity and effective dose intensity].

The cytotoxic activity of cancer chemotherapy is related to the dose and to the amount of drug delivered per time unit. The significance of time in the effectiveness of a treatment program is frequently overlooked. The term of dose intensity (DI) is used to define the drug dose delivered per time unit and is expressed as mg/m2 per week. A delay in the sequence of treatment cycles decreases the DI in the same proportion as a reduction of dose. Average relative DI corresponds to the mean DI of combined agents and is expressed as a fraction of a similar combination selected as a standard. DI is useful to compare the dose actually received with the prescribed dose. The relation of DI with tumor response or survival has not been fully demonstrated. A threshold DI level for therapeutic activity is evident. Above this threshold, a linear relationship of DI and effectiveness is not obvious, particularly regarding high-dose chemotherapy. The term of DI is more useful in its principle than in the significance of its calculated value.

Animals↗
PubMed1975

Influence of sympathetic tone on ventricular fibrillation threshold during experimental coronary occlusion.

The effects of increased and decreased cardiac sympathetic tone and coronary occlusion on ventricular fibrillation were determined in 14 open chest dogs anesthetized with sodium pentobarbital. Heart rate was kept constant by pacing the right atrium at cycle lengths of 500 msec. Ventricular fibrillation threshold was measured by delivering 350 msec trains of constant current stimuli with a frequency of 100 hertz and 2 msec duration. The minimal current of the train that induced fibrillation was taken as the ventricular fibrillation threshold. In seven animals, the effects of stellate stimulation were studied. Ventricular fibrillation threshold was measured during control periods, after 2 minutes of cornoary occlusion, after 2 minutes of stellate stimulation and after 2 minutes of stellate stimulation and coronary occlusion. Coronary occlusion alone decreased ventricular fibrillation threshold an average of 35 percent of control valvues and stellate stimulation alone decreased the threshold an average of 42 percent of control values. The combination of both these interventions decreased ventricular fibrillation threshold an average of 63 percent of control values. The effects of stellate ablation were studied in seven animals. Ventricular fibrillation threshold was measured during control periods, and during coronary occlusion before and after stellate ganglionectomy. Stellectomy increased the threshold an average of 31 percent above control values. After stellectomy, coronary occlusion decreased ventricular fibrillation threshold by only 11 percent of control values, a value 26 percent higher than the threshold during coronary occlusion before stellectomy. These findings may have therapeutic implications for the management of arrhythmias in patients with acute myocardial infarction or some forms of central nervous system disease.

Animals↗
PubMed1988

Irregular pupil cycling as a characteristic abnormality in patients with demyelinative optic neuropathy.

We used an infrared videopupillometer combined with an electronic circuit that regulated the retinal light level as a function of pupil area to assess the regularity of pupil cycling in normal subjects and in patients with known abnormalities in the pupil light reflex pathways. The light stimulus was turned on whenever pupil area exceeded a preset value. Two types of abnormalities were observed for patients with demyelinative optic neuropathy: a failure of the pupil to cycle despite a preserved pupillary response to a single light pulse; and, for those patients in whom cycling was possible, a characteristic intermittent irregularity in the amplitude of pupil cycling. These abnormalities were not seen in normal subjects or in patients with ischemic optic neuropathy, surgical lesions involving the optic chiasm, Adie's syndrome, or Horner's syndrome.

Adolescent↗