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Reduced Performance (reduced + performance)

Distribution by Scientific Domains

Medical Sciences	70%
Life Sciences	20%

Selected Abstracts

Introduction Strategies Put to the Test: Local Adaptation versus Heterosis

CONSERVATION BIOLOGY, Issue 3 2004
PHILIPPINE VERGEER
exogamia; introducciones multi-fuente; introducciones uni-fuente; Succisa pratensis Abstract:,Plant biodiversity has declined seriously because of both habitat deterioration and habitat fragmentation. As a result, many species have been forced into small, fragmented, and isolated populations and are believed to suffer from higher extinction risks. Genetic reinforcement and the establishment of new populations are now widely used to prevent extinction. However, the genetic background of transplants may seriously affect the long-term success of these populations because increased genetic variation may reduce the risk of inbreeding or lead to better performance by restored heterozygosity levels (heterosis). Introduced transplants, however, may be poorly adapted to the new local conditions. We tested the initial success of alternative introduction strategies. We evaluated the potential for inbreeding, heterosis, and/or local adaptation after introduction of artificial populations of Succisa pratensis. We introduced individuals from local and distant artificial populations that were created from either small or large populations. We created the artificial populations with the same census population size but varying effective population sizes by adjusting the relatedness of individuals. We analyzed the demographic consequences of inbreeding, heterosis, and/or local adaptation of these artificial populations. Reduced performance after selfing was manifested by a reduction in seed production, seed weight, germination, and flowering percentage. Seed production, seed weight, flowering percentage, and number of flowerheads were negatively affected by small population size. Local adaptation increased biomass and flowering percentage for local individuals. Seed weight and seed production exhibited significant heterosis. Our results demonstrate that threatened populations can benefit from introduction and genetic reinforcement of individuals from related populations. Significant differences among the artificial populations for several measured performance components suggest that introduction or reinforcement is best achieved through material from a local population or, when unavailable, from several large populations. Resumen:,La biodiversidad de plantas ha declinado seriamente tanto por el deterioro como la fragmentación de hábitats. Como resultado, muchas especies han sido relegadas a poblaciones pequeñas, fragmentadas y aisladas cuyos riesgos de extinción se piensa que son mayores. El reforzamiento genético y el establecimiento de poblaciones nuevas se utilizan ampliamente en la actualidad para prevenir la extinción. Sin embargo, los antecedentes genéticos de transplantes pueden afectar seriamente el éxito de estas poblaciones a largo plazo debido a que el incremento en la variación genética puede reducir el riesgo de endogamia o puede conducir a un mejor rendimiento por lograr niveles de heterocigosidad restaurados (heterosis). No obstante, los trasplantes introducidos pueden adaptarse deficientemente a las nuevas condiciones locales. Probamos el éxito inicial de estrategias de introducción alternativas. Evaluamos el potencial de endogamia, heterosis y/o adaptación local después de la introducción de poblaciones artificiales de Succisa pratensis. Introdujimos individuos de poblaciones locales y de poblaciones artificiales distantes que fueron creadas a partir de poblaciones tanto pequeñas como grandes. Las poblaciones artificiales fueron creadas con el mismo tamaño poblacional censal pero variaron en tamaños poblacionales efectivos al ajustar la parentela de los individuos. Analizamos las consecuencias demográficas de la endogamia, heterosis y/o adaptación local de estas poblaciones artificiales. Después de la autofecundación se manifestó una reducción en el rendimiento por reducción en la producción y peso de semillas y en el porcentaje de germinación y floración. La producción y peso de semillas, el porcentaje de floración y el número de botones florales fueron afectados negativamente por el tamaño poblacional pequeño. La adaptación local incrementó la biomasa y el porcentaje de floración en individuos locales. El peso y producción de semillas mostró heterosis significativa. Nuestros resultados demuestran que las poblaciones amenazadas pueden beneficiarse de la introducción y del reforzamiento genético de individuos de poblaciones emparentadas. Las diferencias significativas entre las poblaciones artificiales en varios de los componentes de rendimiento medidos sugiere que la introducción o reforzamiento se logra mejor con material de una población local o, cuando no disponible, con material de varias poblaciones grandes. [source]

Cognitive dysfunction and health-related quality of life after a cardiac arrest and therapeutic hypothermia

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 6 2010
J. TORGERSEN
Background: Evidence-based treatment protocols including therapeutic hypothermia have increased hospital survival to over 50% in unconscious out-of-hospital cardiac arrest survivors. In this study we estimated the incidence of cognitive dysfunctions in a group of cardiac arrest survivors with a high functional outcome treated with therapeutic hypothermia. Secondarily, we assessed the cardiac arrest group's level of cognitive performance in each tested cognitive domain and investigated the relationship between cognitive function and age, time since cardiac arrest and health-related quality of life (HRQOL). Methods: We included 26 patients 13,28 months after a cardiac arrest. All patients were scored using the Cerebral Performance Category scale (CPC) and Mini-Mental State Examination (MMSE). Twenty-five of the patients were tested for cognitive function using the Cambridge Neuropsychological Test Automated Battery (CANTAB). These patients were tested using four cognitive tests: Motor Screening Test, Delayed Matching to Sample, Stockings of Cambridge and Paired Associate Learning from CANTAB. All patients filled in the Short Form-36 for the assessment of HRQOL. Results: Thirteen of 25 (52%) patients were classified as having a cognitive dysfunction. Compared with the reference population, there was no difference in the performance in motor function and delayed memory but there were significant differences in executive function and episodic memory. We found no associations between cognitive function and age, time since cardiac arrest or HRQOL. Conclusion: Half of the patients had a cognitive dysfunction with reduced performance on executive function and episodic memory, indicating frontal and temporal lobe affection, respectively. Reduced performance did not affect HRQOL. [source]

Mal de Debarquement and Posture: Reduced Reliance on Vestibular and Visual Cues

THE LARYNGOSCOPE, Issue 3 2004
Zohar Nachum MD
Abstract Objective The neural mismatch theory assumes that the intersensory conflicts leading to motion sickness are resolved by changes in the relative weighting of the various senses that contribute to orientation. If this sensory rearrangement persists after disembarkment, it might result in mal de debarquement (MD): ataxia and a rocking sensation sometimes felt after landing. The objective of the present study was to examine possible changes in sensory organization in naval crew members with differing susceptibility to MD with computerized dynamic posturography (CDP). Study Design Cross-sectional parallel-group design. Methods Seventeen subjects susceptible to MD (SMD) and 17 subjects nonsusceptible to MD (NSMD) (healthy male volunteers aged 18,22) participated in the study. CDP was performed twice with each subject, before and immediately after sailing, using the EquiTest system (NeuroCom, Inc., Clackamas, OR). Results The SMD group showed a significant reduction in their scores on sensory organization tests 3, 4, and 5 after sailing. Sensory pattern analysis revealed reduced use of inputs from the vestibular and visual systems to maintain balance. Prolonged latencies of the motor responses to unexpected pitch perturbations were also recorded in the postsailing CDP of the SMD group. Reduced performance on the presailing CDP task, which presents the greatest challenge to the vestibular system, was found to control for the presence of MD postsailing. Conclusions The results show that MD is associated with postural instability, slower motor reflexes, and larger sways in response to abrupt changes in the body's center of gravity. These findings may be explained by under reliance on vestibular and visual inputs and increased dependence on the somatosensory system for the maintenance of balance. [source]

Cognitive dysfunction and health-related quality of life after a cardiac arrest and therapeutic hypothermia

Repetition effect in visual recognition of letters1

JAPANESE PSYCHOLOGICAL RESEARCH, Issue 2 2004
TOSHINORI KUWANA
Abstract:, This study examined the influence of the repetitive presentation of a letter on the recognition of two letters. In two experiments4, two letters, which were either identical or not, were presented successively for a short duration at different spatial locations, and the subjects were required to identify them. In Experiment 1, the presentation time of the first letter was varied, whereas that of the second letter was constant. The results revealed that a reduced performance in identifying a second letter was observed in the case that the first letter, which was identical to the second letter, could be identified correctly. Experiment 2 examined whether or not this reduction was due to the identity of the visual shape of two letters. The first letter was presented either in the usual vertical orientation or rotated orientation by 180 degrees and the second letter was constantly presented in the usual orientation. The results revealed that a reduced performance in identifying a repeated letter was observed, regardless of the orientation of the first letter. The findings from the two experiments suggested that the identity of the information in memory was a main cause of the interference effect by repetition. [source]

Rapid evolution towards heavy metal resistance by mountain birch around two subarctic copper,nickel smelters

JOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2008
J. K. ERÄNEN
Abstract Adaptations to pollution among long-lived trees have rarely been documented, possibly because of their long reproductive cycles and the evolutionarily short timescales of anthropogenic pollution. Here, I present the results of a greenhouse experiment that suggest rapid evolutionary adaptation of mountain birch [Betula pubescens subsp. czerepanovii (Orlova) Hämet-Ahti] to heavy metal (HM) stress around two copper,nickel smelters in NW Russia. The adaptation incurs a cost with reduced performance of adapted seedlings in pristine conditions. The industrial barrens around the studied smelters are extremely high-stress sites with low seed germination and survival. It is likely that strong natural selection has eliminated all sensitive genotypes within one or two generations, with only the most tolerant individuals persisting and producing adapted seeds in the individual barrens. The results were similar from around both smelters, suggesting parallel evolution towards HM resistance. [source]

Ethanol Attenuates Spatial Memory Deficits and Increases mGlu1a Receptor Expression in the Hippocampus of Rats Exposed to Prenatal Stress

ALCOHOLISM, Issue 8 2009
Vincent Van Waes
Background:, Although it is generally believed that chronic ethanol consumption impairs learning and memory, results obtained in experimental animals are not univocal, and there are conditions in which ethanol paradoxically improves cognitive functions. In the present work, we investigated the effects of prenatal stress and of chronic ethanol exposure during adulthood on spatial memory in rats. Methods:, Rats were subjected to a prenatal stress delivered as 3 daily 45-minute sections of restraint stress to the mothers during the last 10 days of pregnancy (PRS rats). After 7 months of ethanol exposure (ethanol 10%, oral intake), memory performances were evaluated in a spatial discrimination test in control and PRS male rats. Then, the oxidative damages and the expression of metabotropic glutamate (mGlu) receptors were assessed in their hippocampus. Results:, Chronic ethanol exposure resulted in a reduced performance in a spatial recognition task in control animals. Unexpectedly, however, the same treatment attenuated spatial memory deficits in rats that had been subjected to prenatal stress. This paradigm of ethanol administration did not produce detectable signs of oxidative damage in the hippocampus in either unstressed or PRS rats. Interestingly, ethanol intake resulted in differential effects in the expression of mGlu receptor subtypes implicated in mechanisms of learning and memory. In control rats, ethanol intake reduced mGlu2/3 and mGlu5 receptor levels in the hippocampus; in PRS rats, which exhibited a constitutive reduction in the levels of these mGlu receptor subtypes, ethanol increased the expression of mGlu1a receptors but did not change the expression of mGlu2/3 or mGlu5 receptors. Conclusion:, Our findings support the idea that stress-related events occurring before birth have long-lasting effects on brain function and behavior, and suggest that the impact of ethanol on cognition is not only dose- and duration-dependent, but also critically influenced by early life experiences. [source]

A behavioural investigation of human visual short term memory for colour

OPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 5 2010
V. A. Nemes
Abstract We examined visual short term memory (VSTM) for colour using a delayed-match-to-sample paradigm. In these experiments we measured the effects of increasing inter-stimulus interval (ISI), varying between 0 and 10 s, on the ability of five colour normal human observers to make colour matches between a reference and subsequently presented test stimuli. The coloured stimuli used were defined by different chromatic axes on the isoluminant plane of DKL colour space. In preliminary experiments we used a hue scaling procedure to identify a total of 12 colour stimuli which served as reference hues in the colour memory experiments: four stimuli were exemplars of red, green, blue and yellow colour appearance categories, four were located between these categories and a further four were located on the cardinal axes that isolated the activity of the cone-opponent mechanisms. Our results demonstrate that there is a reduction in the ability of observers to make accurate colour matches with increasing ISIs and that this reduced performance was similar for all colour stimuli. However, the shifts in hue that were measured between the reference and matched test stimuli were significantly greater for the cardinal stimuli compared to those measured for the stimuli defined by the hue scaling procedure. This deterioration in the retention of hue in VSTM for stimuli that isolate cone-opponent mechanisms may be a reflection of the reorganisation of colour processing that occurs in the cortex where colour appearance mechanisms become more prominent. [source]

Functional impairment after latissimus dorsi flap

ANZ JOURNAL OF SURGERY, Issue 1-2 2009
Cherry E. Koh
Abstract Background:, Available published reports suggest that loss of latissimus dorsi muscle following latissimus myocutaneous flap does not lead to functional impairment. However, significant functional impairment has been observed in clinical practice, prompting this study to evaluate the functional deficit in patients who had undergone reconstruction using latissimus dorsi muscle. Methods:, A retrospective review was undertaken between 1998 and 2003. Patients were identified from the audit of the plastic surgery unit at St Vincent's Hospital and recruited by direct telephone contact. They were assessed using the Disability of Arm, Shoulder and Hand questionnaire. Results:, There were 25 participants. Eighteen completed their questionnaires. Six of 18 patients reported scores of 30 or more, which corresponded to a global moderate functional deficit. These patients were severely limited in their ability to carry out housework. Major postoperative complications were associated with high Disability of Arm, Shoulder and Hand scores (P = 0.028). Three of five patients involved with sports reported impaired performance in sports. The subgroup of four patients who underwent bilateral latissimus dorsi flaps also experienced significant morbidity with all four reporting moderate to severe impairment in their ability to return to gardening and/or sports. Conclusion:, Patients undergoing this procedure should be fully informed of potential sequelae. Athletic patients and patients undergoing bilateral latissimus dorsi flaps should also be warned of possible reduced performance in sports. Alternatively, perforator cutaneous flaps, which preserve the latissimus muscle, should be chosen when feasible. [source]

LUTS/BPH in clinical practice: the importance of nocturia and quality of sleep

BJU INTERNATIONAL, Issue 2006
EMMANUEL CHARTIER-KASTLER
Various studies indicate that nocturia is one of the most bothersome of lower urinary tract symptoms suggestive of benign prostatic hyperplasia (LUTS/BPH). Nocturia has a negative impact on quality of sleep (QoS), which might lead to daytime fatigue, reduced performance the next day and might ultimately affect the patient's overall quality of life (QoL). However, the evaluation of a patient with LUTS/BPH and assessment of benefits of LUTS/BPH treatment are mainly focused on voiding symptoms or flow rate, and the impact of nocturia on the patient's QoL is often neglected. At the Sixth International Consultation on Prostate Cancer and Prostate Diseases in 2005, a discussion forum about nocturia and its impact on QoS and QoL was organized, followed by a meeting of an expert consensus panel. Both recognized the importance of assessing nocturia and its impact on QoS and QoL in the initial evaluation of patients with LUTS/BPH, and in assessing the benefits of (new) LUTS/BPH treatments. However, currently used instruments that measure the severity of nocturia and its impact on QoS and QoL were not specifically designed for this purpose and lack sensitivity. At the expert consensus meeting, the expert panel stated that new instruments are required that can fully monitor the impact of nocturia on QoS and QoL. Potential new instruments that address these requirements are nocturia-specific questionnaires such as the Nocturia QoL questionnaire. Furthermore, the expert panel acknowledged the assessment of ,hours of undisturbed sleep' (HUS) as a potential new method to evaluate the impact of nocturia on QoS and QoL. HUS refers to the time from falling asleep to the first awakening to void. Sleep assessment tools such as sleep diaries and actigraphy are potential instruments to measure HUS. [source]