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PubMed2004

Structural characteristics of purified beta-conglycinin from soybeans stored under four conditions.

Four storage conditions including adverse conditions [84% relative humidity (RH), 30 degrees C], mild conditions (57% RH, 20 degrees C), cold conditions (4 degrees C), and uncontrolled ambient conditions were used for storing soybeans. The storage time was 9 months for the adverse conditions and 18 months for the other three conditions. Beta-conglycinin was purified and characterized with respect to its molecular properties. After storage under the adverse conditions, beta-conglycinin showed no significant changes in total sugar content, surface hydrophobicity, free SH and SS bonds, and amino acid composition within 6 months; however, it showed a significant decrease in surface hydrophobicity and a significant increase in total free SH and total SH including SS content after 6 months. Analysis of the secondary structure showed a significant increase in alpha-helix content, but a significant decrease in beta-sheet content after 3 months. For the other three conditions, no significant changes occurred to the structures of beta-conglycinin when compared to the control. The molecular mass of beta-conglycinin remained in the range of 199-212 kDa for all conditions during the entire storage periods.

Amino Acids↗
PubMed2004

Health-related quality of life associated with chronic conditions in eight countries: results from the International Quality of Life Assessment (IQOLA) Project.

CONTEXT: Few studies and no international comparisons have examined the impact of multiple chronic conditions on populations using a comprehensive health-related quality of life (HRQL) questionnaire. OBJECTIVE: The impact of common chronic conditions on HRQL among the general populations of eight countries was assessed. DESIGN: Cross-sectional mail and interview surveys were conducted. PARTICIPANTS AND SETTING: Sample representatives of the adult general population of eight countries (Denmark, France, Germany, Italy, Japan, The Netherlands, Norway and the United States) were evaluated. Sample sizes ranged from 2031 to 4084. MAIN OUTCOME MEASURES: Self-reported prevalence of chronic conditions (including allergies, arthritis, congestive heart failure, chronic lung disease, hypertension, diabetes, and ischemic heart disease), sociodemographic data and the SF-36 Health Survey were obtained. The SF-36 scale and summary scores were estimated for individuals with and without selected chronic conditions and compared across countries using multivariate linear regression analyses. Adjustments were made for age, gender, marital status, education and the mode of SF-36 administration. RESULTS: More than half (55.1%) of the pooled sample reported at least one chronic condition, and 30.2% had more than one. Hypertension, allergies and arthritis were the most frequently reported conditions. The effect of ischemic heart disease on many of the physical health scales was noteworthy, as was the impact of diabetes on general health, or arthritis on bodily pain scale scores. Arthritis, chronic lung disease and congestive heart failure were the conditions with a higher impact on SF-36 physical summary score, whereas for hypertension and allergies, HRQL impact was low (comparing with a typical person without chronic conditions, deviation scores were around -4 points for the first group and -1 for the second). Differences between chronic conditions in terms of their impact on SF-36 mental summary score were low (deviation scores ranged between -1 and -2). CONCLUSIONS: Arthritis has the highest HRQL impact in the general population of the countries studied due to the combination of a high deviation score on physical scales and a high frequency. Impact of chronic conditions on HRQL was similar roughly across countries, despite important variation in prevalence. The use of HRQL measures such as the SF-36 should be useful to better characterize the global burden of disease.

Adult↗
PubMed2002

Stabilities of 58 volatile organic compounds in fused-silica-lined and SUMMA polished canisters under various humidified conditions.

Fused-silica-lined (FSL) canisters and SUMMA polished (SUMMA) canisters were compared for the recoveries and the stabilities of 58 volatile organic compounds (VOCs) at low ppbv (volume/volume) levels under various humidified conditions using a three-stage preconcentration method followed by GC-MS analysis. The target VOCs included non-polar VOCs (e.g. halogenated hydrocarbons and aromatic hydrocarbons) and polar VOCs (e.g. alcohols, ketones, esters, ethers, nitriles and thiols). The three-stage preconcentration method was initially optimized for simultaneous analysis of non-polar and polar VOCs because determination of canister stability is dependent on the accuracy of analytical measurements. The method showed good linearity over the concentration range from 1 to 25 ppbv for all target analytes, and the correlation coefficients were higher than 0.9974. The method detection limits ranged from 0.023 to 0.39 ppbv. The test mixtures loaded in both type of canisters (n = 3) had concentrations of 1.7-2.5 ppbv per compound at ambient pressure under various humidified conditions (%RH = 1.6, 8.0, 27, 39, 53 and >99% with excess water present). All canister samples were initially analyzed on day 0 (after 6-12 h). The effect of competitive adsorption of water vapor and polar VOCs on active sites of interior surface was remarkably observed for SUMMA canisters. Polar VOCs had a greater requirement for water vapor to be present. The RH percentages that ensured good recovery on day 0 were RH > 8% for non-polar VOCs and RH > 27% for polar VOCs (except alcohols under the condition of RH > 99%). All thiols were not recovered from SUMMA canisters under all conditions. FSL canisters showed good recoveries of more than 86% for all VOCs under all conditions on day 0 (except alcohols under the condition of RH > 99%). The recoveries of alcohols in both canisters under the condition of RH > 99% displayed relatively low recoveries in the range 25-76% because of the partitioning effect into condensed water. The canister samples under the conditions of RH 8.0, 27, 53 and > 99% were analyzed for the stability test on days 3, 7, 14 and 28 after loading. All non-polar VOCs were reasonably stable in the FSL canisters under all examined conditions over 28 days. However, several polar VOCs that have relatively lower vapor pressure, e.g. MIBK, butyl acetate and alcohols except ethanol, showed unstable characteristics under relatively dry conditions (RH 8 and 27%) during 28 days. RH > 53% was needed to ensure good stabilities of all analytes except thiols with the recoveries of > 80% over 28 days for both canisters. Although the FSL canister showed good recoveries of more than 86% for thiols on day 0, drastic degradations were observed after day 3 and they were not detected after day 14.

Air Pollutants↗
PubMed1999

Effects of monitoring condition and frequency-altered feedback on stuttering frequency.

The purpose of the study was to examine stuttering frequency during speaking conditions that are believed to mitigate stuttering frequency both with normal nonaltered auditory feedback (NAF) and a known fluency-enhancing feedback. Specifically, stuttering frequency was examined as a function of three monitoring conditions under NAF and frequency-altered feedback (FAF): no monitoring (i.e., speaking alone, in the absence of audio and visual recording), audiovisual monitoring (i.e., speaking alone with audiovisual recording), and audiovisual monitoring with observers (i.e., speaking with audiovisual recording in the presence of two observers). Seven adults and one adolescent who stutter served as participants. Stuttering frequency was differentially affected across monitoring conditions under each auditory feedback condition (p = .027). Post hoc analyses revealed no significant difference in stuttering frequency between the two conditions in the absence of the observers (i.e., no monitoring vs. audiovisual monitoring) under NAF (p = .45). There was, however, a significant difference in stuttering frequency for the no-monitoring and audiovisual-monitoring conditions relative to the audiovisual-monitoring-with-observers condition (p = .0002). There was no statistically significant difference in stuttering frequency across monitoring conditions under FAF (p > .05). The findings are consistent with the notion that during NAF stuttering frequency varies as a function of hierarchical socio-environmental conditions in which inanimate monitoring conditions constitute one entity. Such a relationship does not exist during FAF.

Adult↗
PubMed2003

Condition-dependent sex allocation in a lek-breeding wader, the ruff (Philomachus pugnax).

Sex allocation theory predicts that females should bias the production of offspring towards the sex that will maximize maternal fitness. Here we demonstrate evidence for nonrandom sex allocation by female ruffs (Philomachus pugnax), at both the individual and population level in relation to female condition. At the population level, female condition varies significantly across 3 years and is mirrored by population sex ratio, such that in years when females are in poor condition the population offspring sex ratio is female-biased, while in years when females are in better condition there was little or no bias. In the year when females were in overall poor condition, females in better condition produced more daughters. The same relationship is also revealed by comparing the sex ratios of individual females breeding in two consecutive years in different condition. As the condition of an individual female improves (across years) she tends to produce more female offspring. Although we have shown that, as in other birds, female condition is an important determinant of sex allocation, our results also suggest that such nonrandom allocation does not occur in every year, being particularly strong in a year when females, on average, are in poorer condition. We suggest that our results are consistent with the idea that skewing the sex ratio is likely to carry a cost to females and that it is adaptive only when the fitness differential between sons and daughters is sufficient to outweigh probable costs.

Animals↗
PubMed2000

Secondary conditions and women with physical disabilities: a descriptive study.

OBJECTIVE: To examine secondary conditions and their relationship to life satisfaction in women with physical disabilities. DESIGN: Survey research. SETTING: Metropolitan Philadelphia. PARTICIPANTS: Women aged 18 to 65 years with self-reported functional limitations associated with neurologic, neuromuscular, brain, sensory, arthritic, spinal cord, orthopedic, or other chronic conditions. MAIN OUTCOME MEASURES: Secondary conditions, health status, functional status, and life satisfaction. RESULTS: In the past year, an average of 12 +/- 6.1 (SD) secondary conditions were experienced. Fatigue, mobility, physical deconditioning, spasticity, and joint pain were reported most frequently, followed by depression, chronic pain, access problems, weight problems, and isolation. In comparing women with multiple sclerosis (MS) and those with other disabling conditions, women with MS had higher secondary conditions problem index (SCPI) scores for bladder, bowel, and sexual dysfunction than women in the mixed disability group. Other secondary conditions with the highest SCPI scores remained similar. Self-reported emotional health status and SCPI scores were the only significant predictors of life satisfaction. CONCLUSION: Secondary conditions influence health status and quality of life for women with physical disabilities. Despite differences among disability groups in terms of the type of secondary conditions, common secondary conditions experienced by most women may be amenable to non-disability-specific health promotion programs.

Activities of Daily Living↗
PubMed1996

The cost of preventable conditions in adults with spina bifida.

Adults with spina bifida are at risk of developing secondary health conditions that are causally related to the primary condition and are to some degree preventable. By investigating preventable secondary conditions in adults with spina bifida, we can determine the burden of care that might be reduced if preventive strategies were developed. We audited hospitalizations of adults with spina bifida to gain insight into serious secondary conditions in this population. We reviewed all admissions of adults with spina bifida to a large American tertiary care center (Johns Hopkins Hospital; Baltimore, Maryland) over 11 years. We determined the discharge diagnoses for each admission and the hospital costs associated with admission. We defined preventable secondary conditions in this adult population and calculated the percentage of total admissions and of total costs for these secondary conditions. The patient population consisted of spina bifida patients 18 years and over admitted from January 1982 to December 1992, including 59 females and 39 males. 77 of our patients were identified as white, 20 as black, and 1 as "other". Patient age ranged from 18 to 61 years with an average age of 25.8 years. There were 353 admissions and admissions per patient ranged from 1 to 25 over the 11-year period. The average number of admissions per patient was 3.6 and the average length of stay for all admissions was 11.2 days. Of the 353 total admissions, 166 (47.0%) were due to potentially preventable secondary conditions such as serious urologic infections, renal calculi, pressure ulcers, and osteomyelitis. For admissions due to these secondary conditions, the average length of stay was 12.5 days. The total hospital costs, excluding professional fees, were $175,885, $247,355, and $437,262 for 1990, 1991, and 1992 respectively. Permanent loss of function resulting from secondary conditions, not investigated in this study, can also be a source of long-term financial and psychological cost to the patient. This study found a high number of patients with multiple admissions and that many admissions qualified as potentially preventable. More information is needed if we are to understand the factors associated with secondary health conditions in adults with spina bifida. We need to investigate the roles played by physician and patient knowledge, attitudes, and behaviors in contributing to patient outcome.

Adolescent↗
PubMed2000

Disease-related conditions in relatives of patients with hemochromatosis.

BACKGROUND: Hemochromatosis occurs in approximately 5 white people per 1000 and is usually due to homozygosity for mutations in the HLA-linked HFE gene. Although screening has been proposed, the proportion of homozygotes with conditions related to hemochromatosis is uncertain. METHODS: We studied the prevalence of disease-related conditions among relatives of probands with hemochromatosis. We identified probands who presented to a clinic with signs or symptoms of hemochromatosis or who had elevated transferrin-saturation values. We identified homozygous relatives, mainly siblings, on the basis of HLA identity with the proband and by HFE genotyping. Disease-related conditions were cirrhosis, hepatic fibrosis, elevated amino-transferase values, and hemochromatotic arthropathy. RESULTS: We identified 214 homozygous relatives of 291 homozygous probands. Of the 113 men in this group (mean age, 41 years), 96 (85 percent) had iron overload, and 43 (38 percent) had at least one disease-related condition. Of the 52 men over 40 years of age, 27 (52 percent) had at least one disease-related condition. Of the 101 female homozygous relatives (mean age, 44 years), 69 (68 percent) had iron overload, and 10 (10 percent) had at least one disease-related condition. Of the 43 women over 50 years of age, 7 (16 percent) had at least one disease-related condition. If the proband had a disease-related condition, relatives who were men were more likely to have morbidity than if the proband had no disease-related condition. CONCLUSIONS: A substantial number of homozygous relatives of patients with hemochromatosis--more commonly men than women--have conditions related to hemochromatosis that have yet to be detected clinically.

Adult↗
PubMed2002

Thermoregulatory responses during prolonged upper-body exercise in cool and warm conditions.

The thermoregulatory responses of upper-body trained athletes were examined at rest, during prolonged arm crank exercise and recovery in cool (21.5 +/- 0.9 degrees C, 43.9 +/- 10.1% relative humidity; mean +/- s) and warm (31.5 +/- 0.6 degrees C, 48.9 +/- 8.4% relative humidity) conditions. Aural temperature increased from rest by 0.7 +/- 0.7 degrees C (P< 0.05) during exercise in cool conditions and by 1.6 +/- 0.7 degrees C during exercise in warm conditions (P< 0.05). During exercise in cool conditions, calf skin temperature decreased (1.5 +/- 1.3 degrees C), whereas an increase was observed during exercise in warm conditions (3.0 +/- 1.7 degrees C). Lower-body skin temperatures tended to increase by greater amounts than upper-body skin temperatures during exercise in warm conditions. No differences were observed in blood lactate, heart rate or respiratory exchange ratio responses between conditions. Perceived exertion at 45 min of exercise was greater than that reported at 5 min of exercise during the cool trial (P< 0.05), whereas during exercise in the warm trial the rating of perceived exertion increased from initial values by 30 min (P < 0.05). Heat storage, body mass losses and fluid consumption were greater during exercise in warm conditions (7.06 +/- 2.25 J x g(-1) x degrees C(-1), 1.3 +/- 0.5 kg and 1,038 +/- 356 ml, respectively) than in cool conditions (1.35 +/- 0.23 J x g(-1) x degrees C(-1), 0.8 +/- 0.2 kg and 530 +/- 284 ml, respectively; P < 0.05). The results of this study indicate that the increasing thermal strain with constant thermal stress in warm conditions is due to heat storage within the lower body. These results may aid in understanding thermoregulatory control mechanisms of populations with a thermoregulatory dysfunction, such as those with spinal cord injuries.

Adult↗
PubMed2002

Content and context effects in children's and adults' conditional reasoning.

We have recently shown that children interpret conditional sentences with binary terms (e.g., male/female) in both the antecedent and the consequent as biconditionals (Barrouillet & Lecas, 1998). We hypothesized that the same effect can be obtained with conditionals that do not contain binary terms provided that they are embedded in a context that restricts to only two the possible values on both the antecedent and the consequent. In the present experiment, we asked 12-year-old children, 15-year-old children, and adults to draw conclusions from conditional syllogisms that involved three types of conditional sentence: (1) conditionals with binary terms (BB), (2) conditionals with non-binary terms (NN), and (3) conditionals with non-binary terms embedded in a restrictive context (NNR). As we predicted, BB conditionals elicited more biconditional response patterns than did NN conditionals in all age groups. On the other hand, manipulating the context had the same effect in children but not in adults. Content and context constraints on conditional reasoning along with developmental issues are discussed within the framework of the mental models theory.

Adolescent↗
PubMed2004

Maternal dominance, maternal condition, and offspring sex ratio in ungulate mammals.

Trivers and Willard's suggestion that natural selection favors maternal control of offspring sex ratio in relation to maternal condition has been much debated. The theoretical plausibility of the idea, under some conditions, is firmly established, and there is strong empirical support for conditional sex allocation in some taxa. However, the extent to which this hypothesis can be applied to mammals, particularly ungulates, has been more controversial. We used meta-analysis to review published studies of the Trivers-Willard hypothesis within ungulates and to assess the overall level of empirical support for the hypothesis. Overall, data from 37 studies of 18 species suggested a weak but significant positive correlation between maternal condition and sex ratio (r=+0.09). However, average effect size differed markedly between different categories of studies. Studies using measures of maternal condition that were taken preconception and on the basis of behavioral dominance provided strong evidence for a relationship between maternal condition and the sex ratio (r=+0.17-0.25). In contrast, studies that used morphological or physiological measures of condition that were measured postconception provided little or no evidence for a relationship between maternal condition and sex ratio (r=+0.05-0.06). There are several reasons to suggest that data collected postconception and relying on morphological measures of condition are less likely to capture variables that cause selection for biased sex allocation. In addition, we found that the relationship between sex ratio and maternal condition depended on life-history characteristics; relationships were stronger when sexual size dimorphism was more male biased and when gestation periods were longer. Overall, our analyses suggest that data from ungulates are consistent with the Trivers-Willard hypothesis but only when appropriate measures are used.

Animals↗
PubMed2004

Sex-biased maternal investment in voles: importance of environmental conditions.

Adaptive bias in sex allocation is traditionally proposed to be related to the condition of mothers as well as to the unequal fitness values of produced sexes. A positive relationship between mother condition and investment into male offspring is often predicted. This relationship was also recently found to depend on environmental conditions. We studied these causalities experimentally using a design where winter food supply was manipulated in eight outdoor-enclosed populations of field voles Microtus agrestis. At the beginning of the breeding season in spring, food-supplemented mothers seemed to be in a similar condition, measured as body mass, head width, body condition index and parasite load (blood parasite Trypanosoma), to non-supplemented mothers. Food supplements affected neither the litter size, the reproductive effort of mothers, nor the litter sex ratios at birth. However, food supplementation significantly increased the birth size of male offspring and improved their condition, as indicated by reduced parasite loads (intestinal Eimeria). Interestingly, mothers in good body condition produced larger male offspring only when environmental conditions were improved by food supplements. Although the adaptiveness of variation in mammalian sex ratios is still questionable, our study indicates that mothers in good condition bias their investment towards male offspring, but only when environmental conditions are favourable.

Analysis of Variance↗
PubMed1998

Pain description and severity of chronic orofacial pain conditions.

A multidisciplinary pain centre study of 120 consecutive chronic orofacial pain patients assessed pain description and intensity ratings, gender differences, prevalence of concurrent conditions, and interinstrument relationships of the McGill Pain Questionnaire and visual analogue scale. Pain words chosen by patients to describe conditions were predominantly sensory words, and patients with concurrent conditions often listed words indicating a substantial affective component. Results showed pain intensity ratings of chronic orofacial pain conditions have similar or higher pain ratings when compared with other medical chronic pain conditions such as back pain, cancer pain and arthritis. There was a significantly higher female: male ratio (88:32) with gender playing an important but poorly understood causal role. The most frequent condition diagnosed was atypical facial pain (n = 40), followed by temporomandibular disorder (n = 32), atypical odontalgia (n = 29) and pathology of the orofacial region (n = 19). Temporomandibular disorder was present in 75 of the 120 subjects, as the sole pain complaint (n = 32) or as an associated secondary condition (n = 43), indicating concurrent pain conditions exist and may be related. There were significantly higher total pain scores of the McGill Pain Questionnaire in patients with multiple conditions compared with patients with a single condition. The visual analogue scale showed a significant correlation to the number of words chosen index of the McGill Pain Questionnaire for orofacial pain.

Adolescent↗
PubMed1991

The body condition of feral ponies on Assateague Island.

The summer body condition of 47 adult feral ponies on Assateague Island (off the coast of Maryland, USA) was assessed in June 1988 using a visual body condition scoring system. Winter body condition for 36 of the ponies was assessed in February and March, 1989. The ponies were categorised by gender, reproductive status and location on the island, and body condition scores of the ponies in each category were then compared by statistical analyses. No significant seasonal differences were found in the body conditions of the ponies. However, body condition of stallions was better than that of mares. Also, lactating mares had lower body condition scores than non-lactating mares. Finally, in the summer, ponies on the southern part of the island were in better condition than those on the northern end where food and other resources were more limited. Thus gender, reproductive status and habitat, according to the criteria of this study, all had an effect on the body condition of Assateague Island feral ponies, whereas seasonal effects were not evident. Future studies could clarify the correlation between the condition of the mares during the breeding season and birth rate and survival of foals the following spring.

Animals↗
PubMed1988

Speech masking. II: Simultaneous masking thresholds under "naturalistic" listening conditions.

This article investigates the role of listening conditions in determining thresholds for probe tones masked by natural speech. These thresholds are of interest because they are a sensitive probe of the activity profile, or spectrum, of sounds such as speech in the auditory system. Most human performance tests are carried out under highly artificial listening conditions, which may not reflect how people listen to speech in common listening environments. In this study, reference conditions (similar to minimal uncertainty listening conditions used in many performance tests) were compared to a "naturalistic" listening condition and to another, intermediate, condition. In the naturalistic listening condition, listeners did not know the frequency or the position of probe tones; additionally, they were required to attend to the semantic content of sentences. In the reference condition, listeners knew the frequency and position of probe tones masked by single syllables. Average thresholds were elevated by 4 dB in the naturalistic listening condition with respect to the reference condition, and thresholds tended to be elevated more for higher-frequency probe tones. The results provide previously unknown information about the resolution of speech sounds in the auditory system during speech comprehension.

Adolescent↗
PubMed2004

Protection against acoustic trauma by forward and backward sound conditioning.

The purpose of the present study was to determine if short-term sound conditioning provides protection when delivered either before (forward sound conditioning) or after (backward sound conditioning) a traumatic exposure in the guinea pig. Two different sound conditioning paradigms were studied (1 kHz, 81 dB SPL, 24 h; 6.3 kHz, 78 dB SPL, 24 h). The 1-kHz forward sound conditioning paradigm (81 dB SPL, 24 h) protected distortion product otoacoustic emissions (DPOAEs) against a short-duration acoustic trauma (2.7 kHz, 103 dB SPL, 5 min) compared to the group exposed to the acoustic trauma alone. The 1-kHz forward sound conditioning paradigm (81 dB SPL, 24 h) also protected both the auditory brainstem response (ABR) thresholds and DPOAEs against a longer-duration acoustic trauma (2.7 kHz, 103 dB SPL, 30 min). The group exposed to the acoustic trauma alone showed ABR threshold shifts between 15 and 24 dB, and DPOAE amplitude shifts between 11 and 24 dB, while the group with 1-kHz forward sound conditioning showed statistically significant protection at all ABR frequencies and at all DPOAE frequencies. The 1-kHz backward sound conditioning paradigm protected against acoustic trauma (2.7 kHz, 103 dB SPL, 30 min). The ABR thresholds were protected at 1, 2 and 4 kHz, and DPOAEs at all frequencies (except 8 kHz) when compared to the group exposed only to the acoustic trauma. The 6.3-kHz forward sound conditioning paradigm protected against acoustic trauma (5.5 kHz, 109 dB SPL, 30 min) at 6.3, 8 and 10 kHz. The 6.3-kHz backward sound conditioning paradigm showed no protection against acoustic trauma at any DPOAE frequency. Taken together, these findings are important for understanding how the auditory system can be modulated by acoustic stimulation and highlights the importance of the acoustic environment during the recovery process of the auditory system.

Acoustic Stimulation↗
PubMed1979

Effect of a physical conditioning program upon left ventricular ejection fractions determined serially by a noninvasive technique.

6 clinically normal subjects underwent a 3-month physical conditioning program with the ejection fractions determined before and after physical conditioning using a scintillation probe. All subjects achieved a conditioning effect as evidenced by increased treadmill test duration after conditioning (mean duration before conditioning: 658 vs. 715 sec after conditioning; p less than 0.02). All 6 subjects increased resting ejection fractions after conditioning (mean ejection fraction before conditioning: 54.5 +/- 5.4%; mean ejection fraction after conditioning: 67.0 +/- 9.0%; p less than 0.01). Thus, an aerobic physical conditioning program appears to increase resting ejection fractions in normal subjects.

Adult↗
PubMed1990

Dynamic and static conditioning pressures evoke equivalent rapid resetting in rat aortic baroreceptors.

A recent study suggested that exposure of carotid sinus baroreceptors to pulsatile pressures for a period of minutes can decrease the static threshold pressure at which they begin to discharge; that is, the exposure can sensitize baroreceptors. Another study found that the rapid resetting of carotid sinus baroreceptors to elevated conditioning pressures was reduced or eliminated by pulsatile conditioning. In the present study, we tested the responses of aortic baroreceptors in an in vitro preparation to a range of static and dynamic conditioning pressures lasting 15 minutes. Slow test ramps of increasing pressure were used to assess static discharge properties (threshold and gain). To be accepted for analysis (n = 12), each baroreceptor had to successfully complete static and dynamic test sequences for at least three different conditioning mean arterial pressure levels. We measured aortic diameter simultaneously with pressure and baroreceptor discharge. Generally, we found no significant difference between the static pressure threshold measured before and after dynamic conditioning. The static pressure threshold was linearly related to the mean level of the conditioning pressure, and no differences in the slopes of these relations (a measure of the ability of a baroreceptor to rapidly reset) were found between static and dynamic conditioning. After dynamic conditioning, discharge rates returned to near control levels in all cases within a few seconds of the return to static conditioning. Two baroreceptors exposed to the vasodilator nitroprusside throughout the experiment showed similar results. Diameter measurements indicated no role of vessel diameter changes during dynamic or static conditioning. In conclusion, we found no evidence of a long-lasting sensitization of aortic baroreceptors by dynamic pressure inputs.(ABSTRACT TRUNCATED AT 250 WORDS)

Action Potentials↗