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PubMed1990

The effect of rate control on the intelligibility and naturalness of dysarthric speech.

Speaking rates of individuals with severe ataxic dysarthria (n = 4) and severe hypokinetic dysarthria (n = 4) were reduced to 60% and 80% of habitual rates using four different pacing strategies (Additive Metered, Additive Rhythmic, Cued Metered, and Cued Rhythmic). Effects of rate control on sentence and phoneme intelligibility and speech naturalness were examined. Sentence intelligibility improved for both groups, with metered pacing conditions associated with the largest improvement in scores. Similar improvements as speaking rates were reduced were not seen for the phoneme intelligibility task; however, one must recognize that sentence and phoneme intelligibility tasks are different. Slowing the rate of dysarthric speakers did not have as marked an impact on speech naturalness as it did for normal speakers whose naturalness decreased at slowed rates. Metered rate control strategies were associated with the lowest ratings of naturalness for all subject groups. A potential explanation for the discrepancies between the findings for sentence and phoneme intelligibility is offered.

Adult↗
PubMed1998

An empirical study of the effect of the control rate as a predictor of treatment efficacy in meta-analysis of clinical trials.

If the control rate (CR) in a clinical trial represents the incidence or the baseline severity of illness in the study population, the size of treatment effects may tend to very with the size of control rates. To investigate this hypothesis, we examined 115 meta-analyses covering a wide range of medical applications for evidence of a linear relationship between the CR and three treatment effect (TE) measures: the risk difference (RD); the log relative risk (RR), and the log odds ratio (OR). We used a hierarchical model that estimates the true regression while accounting for the random error in the measurement of and the functional dependence between the observed TE and the CR. Using a two standard error rule of significance, we found the control rate was about two times more likely to be significantly related to the RD (31 per cent) than to the RR (13 per cent) or the OR (14 per cent). Correlations between TE and CR were more likely when the meta-analysis included 10 or more trials and if patient follow-up was less than six months and homogeneous. Use of weighted linear regression (WLR) of the observed TE on the observed CR instead of the hierarchical model underestimated standard errors and overestimated the number of significant results by a factor of two. The significant correlation between the CR and the TE suggests that, rather than merely pooling the TE into a single summary estimate, investigators should search for the causes of heterogeneity related to patient characteristics and treatment protocols to determine when treatment is most beneficial and that they should plan to study this heterogeneity in clinical trials.

Humans↗
PubMed2006

Cryopreservation of murine embryos, human spermatozoa and embryonic stem cells using a liquid nitrogen-free, controlled rate freezer.

A Stirling Cycle Cryocooler has been developed as an alternative to conventional liquid nitrogen controlled rate freezers. Unlike liquid nitrogen systems, the Stirling Cycle freezer does not pose a contamination risk, can be used in sterile conditions and has no need for a constant supply of cryogen. Three types of samples from two species (murine embryos, human spermatozoa and embryonic stem cells), each requiring different cooling protocols, were cryopreserved in the Stirling Cycle freezer. For comparison, cells were also frozen in a conventional liquid nitrogen controlled rate freezer. Upon thawing, the rates of survival of viable cells were generally greater than 50% for mouse embryos and human embryonic stem cells, based on morphology (mouse embryos) and staining and colony formation (human embryonic stem cells). Survival rates of human spermatozoa frozen in the Stirling Cycle freezer, based on motility and dead cell staining, were similar to those of samples frozen in a conventional controlled rate freezer using liquid nitrogen.

Animals↗
PubMed2003

Propafenone versus ibutilide for post operative atrial fibrillation following cardiac surgery: neither strategy improves outcomes compared to rate control alone (the PIPAF study).

BACKGROUND: It is unclear whether acute conversion of atrial fibrillation (AF) with anti-arrhythmic drugs following cardiac surgery restores and/or maintains sinus rhythm or reduces hospital length of stay (LOS). MATERIAL/METHODS: A randomized prospective pilot study was conducted in 2 teaching hospitals from 3/28/98 to 8/2/99 to study the effect of the early use of ibutilide or propafenone on the duration of AF, rhythm at discharge, and LOS. A total of 42 stable patients with new AF after surgery were randomized to oral propafenone (600mg, single dose; n=20), ibutilide (1 mg up to 2 doses if necessary; n=10), or rate control only (n=12). Agents used for rate control were left to the discretion of the primary physician but beta-blockers were encouraged. RESULTS: Pre-randomization distribution of diabetes, CHF, previous AF, and the use of beta-blockers were similar in all groups. At 24 hours 0%, 65% and 34% of patients in the ibutilide (p=0.01), propafenone (p=ns), and rate control groups respectively remained in AF. Although ibutilide decreased AF duration, recurrence rates were 90%, 41%, and 58% in those groups (p=ns compared to rate control). Of the 3 patients who did not convert, all received propafenone. There was no difference in LOS or rhythm at discharge. CONCLUSIONS: Ibutilide but not propafenone decreases the duration of AF after cardiac surgery and neither appears to affect LOS or rhythm at discharge. This data suggests that post operative AF is transient and routine anti-arrhythmic therapy is not necessary for the majority of patients.

Adrenergic beta-Antagonists↗
PubMed1990

Vagal heart rate control after percutaneous transluminal coronary angioplasty.

Impairment of vagal heart rate control is common in coronary artery disease. To evaluate whether percutaneous transluminal coronary angioplasty (PTCA) has any beneficial effect on this impairment we measured heart rate responses to deep breathing and to standing up, standard tests of cardiac parasympathetic activity, in 28 patients before and 4 weeks after successful PTCA. Before PTCA, 10 patients (36%) had an abnormal heart rate response to deep breathing and one patient (4%) an abnormal response to standing up. The heart rate responses did not change significantly from the preoperative values after PTCA. Thus, the relief of critical coronary obstruction by PTCA seems to have no beneficial effect on vagal heart rate control.

Adult↗
PubMed1998

Rate control and sinus rhythm maintenance in atrial fibrillation: national trends in medication use, 1980-1996.

BACKGROUND: Little is known about national patterns of pharmacological treatment of atrial fibrillation, in particular, use of medications for ventricular rate control and for restoration and maintenance of sinus rhythm. METHODS: We analyzed 1555 visits by patients with atrial fibrillation to randomly selected office-based US physicians included in National Ambulatory Medical Care surveys conducted in 1980, 1981, 1985, and 1989 through 1996. To determine national trends, we evaluated the proportion of atrial fibrillation visits with reported use of rate control medications (digoxin and antiarrhythmics in classes II and IV) and sinus rhythm medications (classes IA, IC, and III). RESULTS: The use of rate control agents decreased from 79% of atrial fibrillation visits in 1980-1981 to 62% in 1994-1996. Declining use was noted for both digoxin (76% in 1980-1981 to 53% in 1994-1996) and beta-blockers (19%-13%). After their introduction, the use of verapamil hydrochloride and diltiazem hydrochloride increased to 15% of atrial fibrillation visits in 1994-1996. Sinus rhythm agent use decreased from 18% of visits in 1980-1981 to 4% in 1992-1993 and then rose to 13% in 1994-1996. The use of class IA agents declined from 18% in 1980-1981 to 3.5% in 1992-1993 and then increased to 8% in 1994-1996. Quinidine remained the most widely used sinus rhythm medication, despite its declining share of this category. Newly available sotalol hydrochloride and amiodarone hydrochloride were used in 3.6% of visits in 1994-1996. CONCLUSIONS: Despite changes in the treatment of atrial fibrillation, digoxin remains the dominant rate control medication. Medications for sinus rhythm maintenance are not widely used. Quinidine use declined prominently in the 1980s, possibly because of concerns about proarrhythmic effects. The use of sinus rhythm agents, however, is now rising.

Adrenergic beta-Antagonists↗
PubMed2003

Rhythm or rate control in atrial fibrillation: insights from the randomized controlled trials.

Pharmacologic treatment remains the mainstay of therapy in patients with atrial fibrillation for the maintenance of normal sinus rhythm. Initial therapy of atrial fibrillation is often directed toward the maintenance of sinus rhythm by means of cardioversion and the use of antiarrhythmic drugs. Heart rate control is often only pursued when rhythm control fails. Four randomized controlled trials have carefully evaluated the yield of these two treatment strategies as the initial approach to patients with paroxysmal or persistent atrial fibrillation. In essence, all four trials demonstrated that an initial strategy of rate control is equally effective compared to the rhythm control approach in terms of clinically important outcome measures including mortality, stroke prevention, or quality of life. Accordingly, rate control can be considered as an initial approach to therapy in patients with paroxysmal or persistent atrial fibrillation. The four randomized trials clearly demonstrate that continuous anticoagulation is mandatory in all patients with atrial fibrillation and risk factors for stroke, irrespective of the initial therapeutic approach of rhythm or rate control.

Anti-Arrhythmia Agents↗
PubMed1994

Effect of radiation fraction size on local control rates for early glottic carcinoma. A model analysis for in vivo tumor growth and radio-response parameters.

BACKGROUND: Two recent studies have suggested that the probability of local control for early glottic carcinoma (stages T1 and T2) following radiation therapy is lower when daily fractions of 1.8 Gy are given instead of 2.0 Gy when the total dose is kept constant at approximately 66 Gy. METHODS: We reviewed our experience with a total of 42 patients with T1, N0, M0 squamous cell carcinoma of the glottic larynx who were treated with radiation alone during the period 1979 to 1989. All patients received conventional fractionation radiation therapy (one treatment per day, 5 days per week). Eight patients received 2.0 Gy per fraction for an average total dose of 64.8 Gy, and 34 patients received 1.8 Gy per fraction for an average total dose of 66.7 Gy. We also calculated overall survival statistics. Combining the clinical data from our series and those of patients from other series (171 total patients), we analyzed the tumor response curve and doubling time for early glottic carcinoma by using a time-dependent, linear quadratic equation model. The analysis is valid for the typical range of radioresponsiveness for most tumors in healthy tissue. RESULTS: Using statistical z analysis, we noted a significant difference in the local control rates at 5 years, with better local control in the group that received 2.0 Gy per fraction (100% vs 70%). Our results for the calculated doubling time and tumor response curves correspond with experimental values for in vitro squamous cell carcinoma systems. CONCLUSION: It appears from the literature and from our data that the control rates for T1, N0, M0 glottic carcinoma may be significantly improved by using 2.0 Gy per fraction dose vs 1.8 Gy per fraction dose. Our analysis has provided a model of in vivo tumor response of early glottic carcinomas based on reported local control rates using these two different treatment regimens.

Carcinoma, Squamous Cell↗
PubMed1998

Auditory vs visual speech timing cues as external rate control to enhance verbal intelligibility in mixed spastic-ataxic dysarthric speakers: a pilot study.

Metronome, singing, and board pacing were used as external rate control techniques for the purpose of comparing the effectiveness of auditory and visual speech timing cues for reducing speech rate and increasing intelligibility in three traumatically brain injured mixed spastic-ataxic dysarthric speakers. A single system design with baseline reversal (ABACAD) was used in this preliminary investigation. Results demonstrated statistically significant (p < 0.05) changes in increased speech intelligibility during all three pacing conditions for the two more involved subjects. Differences between treatment conditions were not statistically significant. However, auditory metronome cuing showed the best results for the two subjects who benefited from rate control. Lower baseline intelligibility was strongly correlated with higher benefit from rate control. Furthermore, the two auditory rhythmic pacing conditions exhibited a close synthronization effect between the frequency rate of the cue and speech rate. Significant correlation coefficients between decreased speech rate and increased intelligibility were only found for the two more involved subjects. These findings suggested a differential benefit of slowing speech rate to improve intelligibility contingent upon severity of speech deficits.

Adult↗
PubMed1983

Effects of dietary sodium restriction on heart rate control in rats.

The effects of dietary sodium restriction on heart rate control were evaluated in male Wistar rats maintained for 4 wk on a low- (22 meq/kg diet) or standard (141 meq/kg diet) sodium diet. In conscious low-sodium rats, atropine produced heart rate increases greater than in standard sodium animals, indicating that basal parasympathetic tone was elevated. Sodium restriction did not affect basal sympathetic tone, since similar reductions in heart rate were produced by propranolol in both dietary groups. However, sympathetically mediated tachycardic responses to sodium nitroprusside were augmented in low-sodium rats. This enhancement of sympathetic function was also observed in low-sodium animals after pithing. The increases in heart rate produced by spinal sympathetic stimulation were significantly accentuated; whereas, responses to norepinephrine were not affected by the diets. This finding is in agreement with the observation that the chronotropic responses elicited by isoproterenol in isolated atria were not altered. When neuronal influences on heart rate were blocked by combined administration of atropine and propranolol or chlorisondamine in conscious rats, the underlying intrinsic cardiac rate was found to be significantly higher in low-sodium rats. In summary, the present study identifies three effects of sodium restriction on heart rate control in the rat: 1) basal parasympathetic tone is increased, 2) heart rate responses to sympathetic activation are enhanced, and 3) the intrinsic cardiac rate is elevated.

Animals↗
PubMed1984

[Relationship between histological classification and local control rate in cases of carcinoma of the uterine cervix].

One hundred and seven cases (53 of fast neutrons and 54 of photons) of stage 3b and 4a carcinoma of the uterine cervix wer treated by irradiation between November, 1975 and November, 1979 at the National Institute of radiological Sciences Hospital. These cases were analyzed with regard to the relationship between histological types (K.L.S. and R.S. classification) and local control rate. Local control rates of fast neutrons and photons were 75% and 67% in general materials, 78% and 58% in L type classification, 55% and 52% in R type and 85% and 76% in S type, respectively. There was no significant difference between the neutrons and the photons.

Carcinoma, Squamous Cell↗
PubMedDate not supplied

Heart rate control and aversive stimulation.

College students were required to train heart rate control (heart rate increase and decrease) with visual feedback for three sessions in a within-person design. In the second and third sessions a test period was added when electric shocks were delivered during half in the trials. Subjects had been grouped in advance in an Aware and an Unaware group on the basis of the Automatic Perception Questionnaire (APQ). The results contradicted some findings by other authors which claim that biofeedback can be used to ameliorate subjective effects of aversive stimulation. Alternative interpretations of the discrepant findings were discussed in terms of expectancy effects that may influence autonomically Aware subjects more strongly than Unaware subjects.

Adult↗
PubMed1997

The effect of atrial fibrillation and the ventricular rate control on exercise capacity.

BACKGROUND: Atrial fibrillation (AF) is a common cardiac arrhythmia, affecting approximately 1.5 million patients in the United States. HYPOTHESIS: This study was designed to determine the effect of AF and the ventricular rate control during AF on cardiovascular performance as measured by exercise endurance on a standard Bruce protocol. METHODS: Sixty-three patients with AF who underwent exercise stress testing during both sinus rhythm and AF were analyzed. Heart rate, blood pressure, heart rate acceleration, exercise duration, and left ventricular (LV) systolic function were measured. RESULTS: Atrial fibrillation resulted in a small but statistically significant decrease in exercise endurance (426 +/- 180 vs. 402 +/- 168 s, p < 0.05). The drop in exercise tolerance was consistent regardless of the underlying heart condition or adequate ventricular rate control during AF. Heart rate in AF was consistently faster than in sinus rhythm, at rest, and at peak exercise (63 vs. 79 beats/min and 125 vs. 149 beats/min, respectively, p < 0.001). CONCLUSION: Our analyses indicated that (1) the loss of atrioventricular synchrony had minimal effect on cardiovascular performance in patients with preserved LV function, (2) the decrease in cardiovascular performance was related to loss of atrioventricular synchrony but not to underlying heart disease or ventricular rate control, and (3) compensation for the loss of the atrial contribution was provided by consistently faster heart rate during AF.

Atrial Fibrillation↗
PubMed2004

Affinity and intrinsic efficacy (IE) of 5'-carbamoyl adenosine analogues for the A1 adenosine receptor--efforts towards the discovery of a chronic ventricular rate control agent for the treatment of atrial fibrillation (AF).

The SAR for the affinity to the A(1) adenosine receptor and relative intrinsic efficacy (IE, [(35)S]-GTPgammaS binding) of a series of 5'-carbamate and 5'-thionocarbamate derivatives of tecadenoson is described. Based on this SAR, selected compounds were evaluated in guinea pig isolated hearts to determine whether they were partial or full agonists with respect to their negative dromotropism, an A(1) AdoR mediated effect. Progress towards obtaining a partial A(1) AdoR agonist to potentially control ventricular rate during atrial fibrillation has been made with the discovery of several potent partial A(1) AdoR agonists (compounds 13, 14, and 17).

Adenosine↗
PubMed1981

A simple apparatus for controlled rate corneal freezing II.

A corneal freezer without electrical or mechanical function is described. Cooling is achieved by partial immersion of the freezing unit in liquid nitrogen. The cooling rate is controlled by the heat content in the unit and the facility for heat removal from the unit. Corneas are frozen in aluminum vials. Corneas are thawed in less than 30 sec without risk of over heating, when the vials are placed on the metal core of another freezing unit at room temperature.

Animals↗
PubMed1978

Effect of heart-rate control training on heart-rate discrimination.

4 subjects were exposed to discrimination-testing procedures before and later biofeedback training to increase and decrease their heart rates. Results indicated significant increases and decreases in heart rate, as well as a significant improvement in accuracy of discrimination. The results suggest improvements in discrimination may occur as a function of feedback training.

Biofeedback, Psychology↗
PubMed1998

Atrial fibrillation: drug therapies for ventricular rate control and restoration of sinus rhythm.

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, and its prevalence increases with age. Etiologies include coronary artery disease, hypertension, valvular heart disease, thyrotoxicosis, and other cardiac and noncardiac conditions. AF can lead to reversible impairment of left ventricular (LV) function, LV dilatation, clinical heart failure, angina pectoris, stroke, and increased mortality. Digoxin, beta blockers, or calcium channel blockers are used to control ventricular rate in new-onset AF with hemodynamically stable rhythm and in chronic AF where rhythm cannot be restored. These drugs can be used alone or in combination, depending on the clinical situation. The most complete relief of symptoms occurs when sinus rhythm is restored. Class IA, IC, and III antiarrhythmic agents can be used to restore and maintain sinus rhythm in selected patients.

Adrenergic beta-Antagonists↗