Biomedical subjects

R Miralles

Publications and source records attributed to R Miralles.

At least 19 recordsLinked to original sources

PubMed2006

Laterotrusive occlusal schemes and their effect on supra- and infrahyoid electromyographic activity.

The objective of this study was to determine the effects of canine guidance and group function on supra- and infrahyoid electromyographic (EMG) activity. The sample included 40 healthy subjects, 20 with bilateral canine guidance and 20 with bilateral group function. Surface electrodes were used to record the integrated EMG (IEMG) activity of the left supra- and infrahyoid muscles during (1) grinding from intercuspal position to lateral edge-to-edge contact position (with canine guidance or group function), (2) static clenching in edge-to-edge lateral contact position with canine guidance or group function, and (3) grinding from lateral edge-to-edge contact position (with canine guidance or group function) to intercuspal position. IEMG activity in the suprahyoid or infrahyoid muscles was not significantly different with canine guidance or group function. Supra- and infrahyoid IEMG activity in condition 2 was significantly higher than in condition 3, which was significantly higher than in condition 1. Supra- and infrahyoid IEMG activity was not significantly different with canine guidance and group function. Supra- and infrahyoid IEMG activity during the static recording (clenching) was significantly higher than during the dynamic recordings (grinding). Activity during grinding from the lateral edge-to-edge contact position to the intercuspal position was higher than vice versa.

Adolescent↗

PubMed2005

Breathing type and body position effects on sternocleidomastoid and suprahyoid EMG activity.

The objective of this study was to determine the effects of breathing type and body position on sternocleidomastoid and suprahyoid electromyographic (EMG) activity. The sample included 18 subjects with upper costal breathing type (study group) and 15 subjects with costo-diaphragmatic breathing type (control group). All individuals had natural dentition and bilateral molar support. EMG recordings at rest and while swallowing saliva were carried out by placing surface electrodes on the left sternocleidomastoid and left suprahyoid muscles. EMG activity was recorded while standing, seated upright, and in the lateral decubitus position. Upper costal breathing type subjects showed a significantly higher suprahyoid EMG activity at rest than costo-diaphragmatic subjects in all body positions studied (mixed model with unstructured covariance matrix). In the lateral decubitus position, both breathing types showed a significantly higher sternocleidomastoid EMG activity at rest and while swallowing saliva. The suprahyoid muscles demonstrated a significantly higher EMG activity at rest as well as in the lateral decubitus position (mixed model with unstructured covariance matrix). These results are relevant because sternocleidomastoid and suprahyoid muscles play an important role in controlling the head posture and mandible dynamics. The neurophysiological mechanisms involved are discussed.

Adult↗

PubMed2004

Previous cognitive impairment and failure to thrive syndrome in patients who died in a geriatric convalescence hospitalization unit.

Cognitive impairment and depression are commonly associated with poor outcomes in geriatric patients. Both are part of the "failure to thrive syndrome" (FTS), that is a combined group of symptoms as a result from progressive functional, mental and nutritional impairment status in older patients. This paper was aimed at evaluating the presence of FTS in the patients who died in a geriatric convalescence unit (GCU) (intermediate care facility) and comparing the characteristics of patients with primary FTS (not associated with an evident identifiable disease) and secondary FTS (associated with an evident identifiable disease). Finally, we wanted to analyze if the presence of cognitive impairment before admission was associated with the type of FTS. We analyzed 78 patients retrospectively. The presence of the next three conditions was necessary to define the FTS: (i) Impaired functional status and malnutrition. (ii) Cognitive impairment and/or depression. (iii) Absence of improvement, after a specific geriatric intervention program during the hospitalization. Functional status for basic and instrumental activities of daily living (ADL and IADL) and the presence of symptoms cognitive impairment before admission were evaluated. Of the 78 analyzed patients, there were 30 (38.4%) with symptoms of FTS. Seventeen of them (56.6%) had a secondary FTS and 13 (43.3%) a primary one. This last group of patients had a significantly higher mean age (84.7 +/- 5.8 vs. 78.6 +/- 7.2; p < 0.02) and before admission they were significantly more dependent for ADL: 10 patients (76.9%) vs. 7 (41.0%) chi2 = 3.833, p < 0.05. A higher proportion of subjects with cognitive impairment before admission was found in the group of patients with primary FTS, than in those secondary FTS, although this difference did not reach statistical significance. Patients with primary FTS seem to be older and more dependent for ADL before admission, than those with secondary FTS.

Aged↗

PubMed2004

Clinical impact of different scores of the mini nutritional assessment (MNA) in the diagnosis of malnutrition in patients with cognitive impairment.

It was aimed at evaluating the clinical usefulness of the mini nutritional assessment (MNA) to identify malnutrition in elderly patients with cognitive impairment, admitted to a geriatric convalescence unit (intermediate care facility). Sixty-three patients with cognitive impairment were studied. Cognitive impairment was considered when mini mental state examination (MMSE) scores were below 21. MNA and a nutritional evaluation according to the sequential model of the American Institute of Nutrition (AIN) were performed at admission. According to the AIN criteria, malnutrition was considered, if there were abnormalities in at least one of the following parameters: albumin, cholesterol, body mass index (BMI), and branchial circumference. Based on these criteria, 27 patients (42.8%) proved to be undernourished at admission, whereas if taking the original MNA scores, 39 patients (61.9%) were undernourished, 23 (36.5%) were at risk of malnutrition, and 1 (1.5%) was normal. The analyzed population was divided in four categories (quartiles) of the MNA scores: very low (</= 13.5), low (> 13.5 and </= 16), intermediate (> 16 and </= 18.5) and high (> 18.5). Likelihood ratios of each MNA quartile were obtained by dividing the percentage of patients in a given MNA category who were undernourished (according to AIN) by the percentage of patients in the same MNA category who were not undernourished. In the very low MNA quartile, this likelihood ratio was 2.79 and for the low MNA quartile it was 0.49. For intermediate and high MNA categories, likelihood ratios were 1.0 and 0.07 respectively. In the present study, MNA identified undernourished patients with a high clinical diagnostic impact value only, when very low scores (</= 13) are obtained.

Aged↗

PubMed2004

Evaluation of functional improvement in older patients with cognitive impairment, depression and/or delirium admitted to a geriatric convalescence hospitalization unit.

Cognitive impairment, depression and delirium are problems of high prevalence in older patients. The geriatric convalescence unit (GCU) is a hospitalization facility offering an interdisciplinary geriatric intervention program that may be more appropriate for these patients. This study intended to analyze the functional improvement (FI) in older patients with cognitive impairment, depression and/or delirium admitted to a GCU. A group of 107 patients received specific nurse care, habitually performed in GCU and they also were included in a rehabilitation program. Cognitive impairment, depression and delirium were diagnosed according to standardized protocols. The analyzed variables were: age, functional status (Barthel index) before admission (BBA), at admission (BA) and at discharge(BD), diagnostic categories, cognitive function (mini mental state examination: MMSE) and post-discharge destination. The corrected Heinemann index (CHI) was used to evaluate FI obtained during GCU-stay, where CHI = 100 x (BD-BA)/(BBA-BA), and the efficiency index(El) was used to analyze the relationship between FI and the length of stay in the GCU,where El = (BD-BA)/(days in GCU). According to CHI, patients were divided in three groups. Group I: CHI = 0 or negative (patients who lost functional capacity during hospitalization,those who died or were transferred to hospital owing to acute deterioration. Group II: CHI < 35 % (high FI). Mean age was 77.6 +/- 9.1 years, the diagnostic categories were: fractures/orthopedics 49 (45.7 %), neurological 27(25.2 %), pulmonary/cardiologic 6 (5.6 %) and other cases 25 (23.3 %). Mean MMSE and BA scores were 16.9 +/- 9.4 and 29.6 +/- 18.9, respectively. Post-discharge destinations were:63 patients (58.8 %) returned home, 28 (26.1 %) were definitively institutionalized, 11 (10.2%) died and finally 5 (4.6 %) were transferred to acute care hospital. In-Group I, there were 35 patients (32.7 %) with a mean value of the El = 0.12 +/-1.1; in Group II, 13 (12.1 %) and 0.26 +/- 0.38; in Group III, 59 (55.1 %) and 0.94 +/- 0.97, respectively. In spite of the presence of cognitive impairment, depression and/or delirium, a high proportion of patients (67.2 %)obtained a significant improvement in their functional capacity.35 % (moderate FI). Group III: CHI >/=

Aged↗

PubMed2004

Validation of a modified version of the Gijon's social-familial evaluation scale (SFES): the "Barcelona SFES Version", for patients with cognitive impairment.

The aim was to validate an abbreviated version of the Gijon's social-familial evaluation scale (SFES) (Barcelona-SFES version), on patients with cognitive impairment. A group of 34 patients with cognitive impairment, admitted to an intermediate-long-term-care facility, were analyzed. Mean age was 80.2 +/- 7.4 years. Gijón's SFES was abbreviated and only the first three item groups corresponding to family conditions, social contacts and assistance from the social network were selected. Barcelona-SFES version had a range score between 3 to 15 points, in which low scores identify older patients who live with their family, have good contacts, and participate in community activities. In contrast, high scores identify older persons who live alone and have poor social support and little participation with community activities. Three social risk categories were established according to the Barcelona-SFES score: low social risk (>/= 7 points), intermediate social risk (8-9 points) and high social points). Validation criteria used in the present study were: predictive value of Barcelona-SFES score of post-discharge destination (home or institution), and patient's (or family's) request for a definitive institutionalization in a nursing home. There were 9 patients with low social risk (26.4 %), 8 with intermediate social risk (23.5 %) and 17 with high social risk (50 %). A significant relationship between Barcelona-SFES scores and post-discharge destination was found. Eighty percent of patients discharged to an institution(nursing and residential homes), they had high social risk SFES scores (>/= 10) Also, a significant correlation was found between the number of patients for which a definitive institutionalization request was performed and the Barcelona-SFES scores. Fifteen (88.2 %) of the 18 patients for whom the request was done, were in the high social risk group. The lowest scores from SFES were predictive of home discharge, while the highest scores were predictive of a definitive institutionalization.

Aged↗

PubMed2004

Observational scale and geriatric depression scale of Yesavage to identify depressive symptoms in older patients.

The diagnosis of depression by clinical interview may be difficult in the patients with communication problems (aphasia, severe cognitive impairment or severe deafness). In these cases, depressive symptoms may be observed by others (nurses and caregivers). The aim of this study was to evaluate the clinical usefulness of an observational scale to identify depression in older patients. Seventy-six institutionalized patients in an intermediate-long-term care center were evaluated. Of them, 39 were excluded because they were unable to perform a clinical interview, needed to diagnose depression. Of the excluded patients, 18 had aphasia, 7 showed severe cognitive impairment: their mini mental state examination (MMSE) score < 14, and 14 collaborated very poorly. Thus 37 patients were analyzed, mean age was 83 +/- 0.86 years (30 women and 7 men). Diagnostic categories were: neurological 16 patients (43.2%), fractures/orthopedics 6 (16.2%), pulmonary/cardiology 5 (13.5%) and others 10 (27.1%). The mean Barthel index was 57.0 +/- 31.6 and mean MMSE score was 21.1 +/- 4.3. The observational scale (OS) designed with six items, was applied to all patients. Each item was scored as never (0 points), sometimes (1 point) and always (2 points). Thus total OS score ranged from 0 to 12. Two observers, who knew the patients (nurses), applied the OS. A trained geriatrician, using the 15-item geriatric depression scale (GDS) performed detection of depressive symptoms. There were 15 patients (40.5 %) with depression on the GDS. OS scale score with a cutoff point of 5 or more was present in 13 patients; nine of them had depression (69.2 %). In the remaining 24 patients with an OS score < 5, depression was present only in 6 cases (25%) (chi2 = 6.844; p < 0.01). The OS >/= 5, in the present study, obtained a sensitivity of 60 %, a specificity of 81 %, a positive predictive value of 69 %, and a negative predictive value of 75 %.We concluded that (i) the OS has been useful for identifying depressive symptoms with an acceptable sensitivity and specificity, and (ii) the OS may be an alternative to detect depression in patients who are unable to perform a clinical interview.

Aged↗

PubMed2004

Prevalence of delirium in a geriatric convalescence hospitalization unit: patient's clinical characteristics and risk precipitating factor analysis.

The aim was to evaluate the prevalence of delirium among patients discharged from an acute care hospital and admitted to a geriatric convalescence unit (GCU), and to analyze patient's characteristics and risk precipitating factors. Sixty-eight patients were analyzed during a 2-week period. The confusion assessment method (CAM) was used to detect delirium. The precipitating factors evaluated were: major surgery-intensive care unit(ICU) stay, pulmonary and heart failure, acute infections, metabolic disorders/anemia,psychoactive medications, other drugs, severe pain, changing environmental influences and others. According to CAM, fifteen patients presented delirium (22%), and in 14 of them(93.3 %) the delirium was developed before admission at GCU. The precipitating factors in the studied population were the following: changing environmental influences in 66 patients(97%) (15 with delirium and 51 without delirium); other drugs 56 (82.3 %) (11 vs. 45);others 56 (82.3%) (9 vs. 24); psychoactive medications 50 (73.5%) (12 vs. 38); acute infections 48 (70.5 %) (13 vs. 35); metabolic disorders/anemia 40 (58.8 %) (9 vs. 31); major surgery-ICU stay 28 (41 .1%) (8 vs. 20); severe pain 26 (38.2%) (6 vs. 20); pulmonary and heart failure 22 (32.3%) (5 vs. 17). The univariant analysis showed that, none of the precipitating factors studied was significantly related to delirium. Seventy-two patients (91.1%) had simultaneously >3 precipitating factors. There were 16 patients with >6 precipitating factors, 7 of 15 with delirium and 9 of the 53 without delirium (46.6 % vs 16.9 %) (p < 0.05). The prevalence of delirium has been 22 %. Most of the patients had developed delirium before the admission at GCU. A high proportion of patients had >3 precipitating factors. In the study the presence of > 6 precipitating factors simultaneously has been significantly related to delirium.

Aged↗

PubMed2004

On estimating the center frequency of ultrasonic pulses.

In this paper we propose a new technique for estimating the center frequency of the ultrasound pulse from records of backscattering noise. We start by considering that the conventional maximum frequency method can be seen as a filtering (differentiator) of the pulse spectrum magnitude followed by a searching for the zero-crossing value. The new approach replaces the differentiator by a Hilbert transformer. We show in the paper that the proposed method has less variance than the maximum frequency method. In particular, we analyse the performance assuming that the real cepstrum method is used for extracting pulse spectrum magnitude. We give an upper bound for the variance reduction when practical criteria are applied for fitting the cepstrum cut-off frequency. The analytical work is verified by real and simulated data.

Journal Article↗

PubMed2001

Vertical dimension. Part 1: comparison of clinical freeway space.

This study was conducted in order to compare the clinical freeway space measurements using three simple methods commonly used by dentists in their practices. The study was performed in 15 young healthy subjects with natural dentition and bilateral molar support. Artificial landmarks (adhesive tape) were placed on the more prominent parts of the nose and chin of each subject. Vertical dimension of occlusion (VDO) was measured in the intercuspal position. Postural vertical dimension (PVD) was measured in the following functional conditions: after swallowing saliva, after pronouncing the word "Mississippi", and in a relaxed postural mandibular position (RPMP). Then, the clinical freeway space value in each functional condition was obtained by subtracting VDO from PVD value. Significant differences among clinical freeway space values using three different methods were observed (ANOVA). A significantly higher clinical freeway space value was found using phonetics method than after swallowing and with the mandible in a relaxed postural position (Bonferroni multiple comparison test). No significant differences between swallowing and relaxed methods were found. These results seem to suggest that the measures of clinical freeway space depend upon the method used.

Adult↗

PubMed2000

The evolution of RNA viruses: A population genetics view.

RNA viruses are excellent experimental models for studying evolution under the theoretical framework of population genetics. For a proper justification of this thesis we have introduced some properties of RNA viruses that are relevant for studying evolution. On the other hand, population genetics is a reductionistic theory of evolution. It does not consider or make simplistic assumptions on the transformation laws within and between genotypic and phenotypic spaces. However, such laws are minimized in the case of RNA viruses because the phenotypic space maps onto the genotypic space in a much more linear way than on higher DNA-based organisms. Under experimental conditions, we have tested the role of deleterious and beneficial mutations in the degree of adaptation of vesicular stomatitis virus (VSV), a nonsegmented virus of negative strand. We also have studied how effective population size, initial genetic variability in populations, and environmental heterogeneity shapes the impact of mutations in the evolution of vesicular stomatitis virus. Finally, in an integrative attempt, we discuss pros and cons of the quasispecies theory compared with classic population genetics models for haploid organisms to explain the evolution of RNA viruses.

Biological Evolution↗

PubMed2000

Effects of head and neck inclination on bilateral sternocleidomastoid EMG activity in healthy subjects and in patients with myogenic cranio-cervical-mandibular dysfunction.

This study was conducted in order to determine the effect of head and neck position on bilateral electromyographic (EMG) activity of the sternocleidomastoid muscles. The study was performed on 16 patients with myogenic cranio-cervical-mandibular dysfunction (CMD) and 16 healthy subjects. EMG recordings at rest and during swallowing of saliva and maximal voluntary clenching were performed by placing surface electrodes on the right and left sternocleidomastoid muscles. EMG activity was recorded in the left lateral decubitus position, in a darkened room and with the individual's eyes closed, under the following experimental conditions: 1. Head, neck, and body horizontally aligned; 2. Head and neck upwardly inclined with respect to the body, simulating the effect of a thick pillow, 3. Head and neck downwardly inclined with respect to the body, simulating the effect of a thin pillow. Variation of head and neck positions was determined by measuring the distance from the angle of neck and shoulder and the apex of the shoulder (SND = shoulder-neck distance) of each individual. Then, head and neck were forward or downwardly inclined with respect to the body at one-third of SND. A significantly higher contralateral EMG activity and a more asymmetric EMG activity were observed in the CMD group than in the healthy subjects (Kruskal-Wallis Test). These results suggest a different behavior of bilateral sternocleidomastoid EMG activity in CMD patients than in healthy subjects depending on the positioning of the head and neck.

Adult↗

PubMed2000

The two faces of mutation: extinction and adaptation in RNA viruses.

From a population standpoint, two main features characterize the replication of RNA viruses and viruses that use RNA as a replicative intermediate: high genetic variability, and enormous fluctuations in population size. Their genetic variability mainly reflects a lack of the proof-reading and post-replicative error correction mechanisms that operate during cellular DNA replication, but recombination and segment exchange can also play an important role. Viral population size can change tremendously as a consequence of transmission between hosts or between different tissues within an infected host. A new infection can be initiated with very few particles that subsequently expand many trillion-fold. Repeated bottleneck events can lead to drastic fitness losses or even to viral extinction, whereas continuously large population sizes result in fitness gains and adaptation. Here we review experimental evidence for the effects of mutation, selection, and genetic drift on the adaptation and extinction of RNA viruses.

Adaptation, Physiological↗

PubMed2000

Diminishing returns of population size in the rate of RNA virus adaptation.

Whenever an asexual viral population evolves by adapting to new environmental conditions, beneficial mutations, the ultimate cause of adaptation, are randomly produced and then fixed in the population. The larger the population size and the higher the mutation rate, the more beneficial mutations can be produced per unit time. With the usually high mutation rate of RNA viruses and in a large enough population, several beneficial mutations could arise at the same time but in different genetic backgrounds, and if the virus is asexual, they will never be brought together through recombination. Thus, the best of these genotypes must outcompete each other on their way to fixation. This competition among beneficial mutations has the effect of slowing the overall rate of adaptation. This phenomenon is known as clonal interference. Clonal interference predicts a speed limit for adaptation as the population size increases. In the present report, by varying the size of evolving vesicular stomatitis virus populations, we found evidence clearly demonstrating this speed limit and thus indicating that clonal interference might be an important factor modulating the rate of adaptation to an in vitro cell system. Several evolutionary and epidemiological implications of the clonal interference model applied to RNA viruses are discussed.

Adaptation, Physiological↗

PubMed2000

Comparative study between children with and without cleft lip and cleft palate, part 1: cephalometric analysis.

OBJECTIVE: This study was conducted to compare craniofacial relationships, position, and curvature of the cervical spine between children with cleft lip and cleft palate who had been operated on and children without clefts. METHOD: This study was performed in 28 children with mixed dentition. They were divided into two groups. The study group included 14 children with unilateral operated cleft lip and cleft palate, ranging in age from 6 to 12 years, who clinically presented with a short upper lip, abnormal lip seal, and inhibition of sagittal development of the midface that was radiographically assessed. The control group included 14 children without clefts, ranging in age from 8 to 11 years. All of them had normal lip seal, nasal breathing, and a clinically normal body posture. DESIGN: A lateral craniocervical radiograph in a self-balanced natural head position in an erect posture, and without using a head holder, was taken for each child of both groups, with the mandible in maximum intercuspation and lips in habitual posture. The true vertical was marked on all the films. Specific angular and linear dimensions were used to assess the craniocervical relationships, as were the position of the cervical spine, its curvature, or both. RESULTS AND CONCLUSIONS: The study group presented a significant increase in the extension of the head on the neck, forward position of the cervical spine, and a decrease in the curvature of the cervical spine in comparison with the children without clefts. These results are more relevant considering that the study group also presented higher significant values of lower facial height than children without clefts.

Cephalometry↗

PubMed2000

Comparative study between children with and without cleft lip and cleft palate, part 2: electromyographic analysis.

OBJECTIVE: This study was conducted to compare electromyographic (EMG) activity of superior orbicularis oris muscle between children with repaired cleft lip and cleft palate and children without clefts. METHODS: This study included 28 children with mixed dentition. They were divided into two groups. The study group included 14 children with repaired unilateral cleft lip and cleft palate, ranging in age from 6 to 12 years, who presented clinically with a short upper lip, abnormal lip seal, and inhibition of sagittal development of the midface as assessed radiographically. The control group included 14 children without clefts ranging in age from 8 to 11 years. All had normal lip seal, nasal breathing, and a clinically normal body posture. DESIGN: Bipolar surface electrodes were used for EMG recordings of resting level activity and during swallowing of saliva, speech, and chewing and swallowing of an apple. RESULTS AND CONCLUSIONS: A significantly higher level of activity at rest and during swallowing of saliva was observed in the cleft lip and cleft palate group. Similar activity during speech and chewing and swallowing of an apple was observed in both groups. The higher level of activity at rest and during swallowing of saliva in children with cleft lip and cleft palate seems to suggest that upon higher functional demands their activity increases less than in children without clefts. From a clinical point of view, if increased EMG activity at rest and during swallowing of saliva reflects increased force on the maxilla, then our findings may corroborate Bardach's findings (1990) that surgical treatment of cleft lip has an iatrogenic effect on facial growth, although the lack of significant correlation between the cephalometric data and EMG findings in the present study.

Child↗

PubMed2000

[Effectiveness and cost of total hip replacement in seven hospitals in Catalonia, Spain].

BACKGROUND: To quantify short-term benefits of total hip replacement, prognostic factors of the outcome, and to assess hospital costs of this surgical procedure in Catalonia, Spain. PATIENTS AND METHODS: Multicentric prospective study in seven hospitals in Catalonia. All patients undergoing this procedure in one year were included. They were evaluated prior to the operation, and six months later. This evaluation involved: clinical assessment, the Hip Pain and Function Scale, the Nottingham Health Profile (NHP), and the EuroQol (EQ-5D), in order to measure cost-utility. Hospital costs were estimated by means of a specific questionnaire. RESULTS: Information was obtained for 332 patients. The mean age was 65 years (range: 27-89 years); 58% were women; the most common diagnosis was arthritis; 59% of patients had associated pathology and 13% presented some type of postoperative complication. The improvement in health status was important according to all instruments. An outcome of "excellent" or "good" was achieved by 70.8% of the patients, in terms of hip function and pain. The factors associated with not achieving an outcome of this level were: associated pathology, complications, diagnoses other than arthritis, and operation carried out in a tertiary hospital. The total cost of the procedure was 838,480 pesetas. This average varied significantly with the cost of the prosthesis, and as a function of the length of stay. The three-year cost-utility of the procedure was estimated as 507,500 pesetas. CONCLUSIONS: Total hip replacement greatly improves the pain, hip function and overall perceived health of the patient. This improvement is greater among patients with a diagnosis of arthritis, with good overall health, operated on by a surgeon experienced in this procedure. The benefit is high in relation to the cost, although there is a margin for improvement, reducing complications, shortening length of stay, and controlling the price of implants.

Adult↗

PubMed1999

Clonal interference and the evolution of RNA viruses.

In asexual populations, beneficial mutations that occur in different lineages compete with one another. This phenomenon, known as clonal interference, ensures that those beneficial mutations that do achieve fixation are of large effect. Clonal interference also increases the time between fixations, thereby slowing the adaptation of asexual populations. The effects of clonal interference were measured in the asexual RNA virus vesicular stomatitis virus; rates and average effects of beneficial mutations were quantified.

Adaptation, Physiological↗