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Results for “Differential Threshold”

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PubMed2001

Influence of Local Cooling on Proprioceptive Acuity in the Quadriceps Muscle.

OBJECTIVE: To test the influence of cooling on proprioceptive acuity as reflected in the ability to discriminate weights. DESIGN AND SETTING: Participants were trained to perform a weight-discrimination task. Their ability to correctly report small increments in weight was compared before and after local cooling (a 20-minute application of a crushed-ice pack) of the quadriceps muscle group. Data were collected at a university research laboratory. SUBJECTS: Twenty young, physically active adults (undergraduate students; 14 men, 6 women; mean age, 22.1 +/- 2.6 years). MEASUREMENTS: We calculated overall performance in the weight-discrimination task (percentage of discrimination correct) for each participant to estimate the differential threshold (ie, minimal increment in weight that yields a probability of 75% correct responses). RESULTS: Before local cooling, participants discriminated increments in the order of 4% to 10% from the standard weight (mean threshold, 0.17 +/- 0.06 kg). After local cooling, the discriminative performance remained, on average, very similar to that seen before cooling (mean threshold, 0.17 +/- 0.08 kg; paired t test: t = 0.24, P =.81). Only a small group of participants (n = 5) showed evidence of a decreased ability to discriminate weight after cooling. CONCLUSIONS: The perception of force signals required for weight discrimination does not appear to be affected by local cooling of the quadriceps muscle group. This finding provides additional evidence for the relative safety of cold applications and their effect on proprioceptive perceptual abilities.

Journal Article↗
PubMed2002

Effect of the moderate exercise on performance in upper/lower limb during long term bed rest.

The purpose of this study was to investigate that considers the influence of the moderate exercise has on the upper limbs and the legs during 21 days head down bed rest. Therefore motor evoked potential (MEP) induced by transcranial magnetic stimulation (TMS) in lower leg muscles of four healthy subjects were investigated before/after and during bed rest. There were no significant differences statistically between soleus MEPs before and after bed rest in all subjects. However there were decreased tendancy in MEPs during non-exercise group. And then there were not change discriminal ability on differential threshold of weight sensory in scale test in all subjects during head down bed rest. Theses results indicate that the assign cognitive performance, sensory in scale for upper limb no changes during and after head down bed rest.

Journal Article↗
PubMedDate not supplied

[Modulators of intracellular metabolism in the treatment of diseases of the internal ear].

Stress reactions develop in different organs as a result of the effect of unfavourable factors which increase the differential threshold for men. These derangements mainly occur in the organs where we can observe an inadequacy between high level of metabolism in the cell and instability of energy supply. Under such conditions stress reactions in the cells have the following stages in succession: intensiveness of the lipolysis in mitochondria, accumulation in the cells of fatty acid metabolites, destruction of the membranous apparatus of the cells, increase in the presence of Ca++ in the cells.

Animals↗
PubMed1991

Homeostatic equilibrium of L-carnitine family before and after i.v. administration of propionyl-L-carnitine in humans, dogs and rats.

Propionyl-L-carnitine is a minor component of L-carnitine family which, when exogenously administered, proved to possess interesting cardiovascular activities. In this paper the pharmacokinetics of propionyl-L-carnitine was investigated in humans, dogs and rats after intravenous administration. In all the three species the base homeostatic equilibrium was carefully investigated in plasma and in urine during the 24 h period before the administration. Propionyl-L-carnitine, acetyl-L-carnitine, L-carnitine and total acid soluble L-sensitive were assayed in plasma and urine with very sensitive enantioselective radioenzyme assay. After dosing propionyl-L-carnitine rapidly increased, and then decreased reaching the base value within 6 h or more, depending on the species and the dose. Also L-carnitine in all the three species and acetyl-L-carnitine in rats and dogs increased, but the increase was more sustained when compared to propionyl-L-carnitine. Urinary excretion paralleled plasma concentration, reaching the highest value in the 24 h-period after dosing. Renal clearance also increased reflecting the behaviour of plasma concentration and urinary excretion. Results obtained all the conclusion that two homeostatic equilibrium of L-carnitine family components, namely the inter-exchange between L-carnitine and its esters catalyzed by carnitine acyl transferases, and a saturable tubular reabsorption process with differentiated threshold for each component.

Acetylcarnitine↗
PubMed1991

Protein binding of L-carnitine family components.

L-carnitine and its short-, medium- and long-chain acyl esters constitute the L-carnitine family. These compounds in the body are equilibrated according to a homeostatic equilibrium preserved and, when impaired, restored by a dynamic inter-exchange between L-carnitine and its esters, catalysed by carnitine acyl transferases, and a tubular reabsorption process with differentiated thresholds for each component. The interaction of these compounds with albumin and plasma proteins of rats, dogs and humans was carefully investigated by means of ultrafiltration and gel filtration techniques. Results obtained demonstrate that L-carnitine and its short-chain esters, namely acetyl-L-carnitine and propionyl-L-carnitine, do not interact with either albumin or plasma proteins; octanoyl-L-carnitine interacts in a measurable even if poor extent (12-30%), whereas palmitoyl-L-carnitine, a molecule with a detergent activity, is completely bound to albumin and plasma proteins.

Acetylcarnitine↗
PubMed1990

[Characteristics of presbycusis: evaluated by pure tone audiometry].

In order to explore the incidence and course of presbycusis, 82 elderly and aged as well as 16 young persons were studied by Bekesy audiometry, including tone stimuli of different durations, SISI, and tone decay tests. Results showed that the hearing threshold has elevated in all the old persons. Positive correlations were found between age and hearing problems. Based on analyses of the DLI, temporal integration and tone decay tests, characteristics of the cochlear lesion had been suggested and some might exhibit retrocochlear dysfunctions.

Age Factors↗
PubMed1989

Injuries to children in a Native American community.

The rate of hospitalization of children with injuries in one service unit was three times that of the Albuquerque Area Indian Health Service as a whole. To determine the reasons, mortality and hospitalization data were analyzed and an indepth review of medical records was performed. Among the possible explanations for the high injury rate that were excluded were an artifact of reporting, uncertain denominator data, lack of age-adjustment, lower socioeconomic status of the community, differential thresholds for hospitalization, and an increase in a few specific types of injury. Alternative hypotheses involve life-style issues and psychosocial stress. These hypotheses are supported by data concerning alcohol abuse and foster care and have profound implications for injury control efforts in this community.

Accidents↗
PubMedDate not supplied

[Modeling of auditory mechanisms of pitch perception].

A hypothesis of two subordinately interconnected pitch perception systems is put forward and described. The leading system is responsible for the analysis of periodical sequences of spikes along audioneurons whose generation moments are synchronized by the acting sound oscillations. This system allows measuring of any periodical sound--simple or complex--including the residual sound. However, the system of periodicity analysis does not ensure the experimentally determined precision of pitch change perception. It is shown that the signal distribution along the basilar membrane enables the activation of the second system which analyses the spatial--temporal image by means of a great number of well innervated internal receptor cells. This system functioning is characterized by small values of differential threshold pitches, since as a discriminatory characteristic a curt decline of the basilar membrane oscillation envelope is used which is formed after a prolonged sinusoidal sound.

Basilar Membrane↗
PubMed1995

[The follow-up of therapeutic remission in alcoholics].

Usage of alcohol during the period of therapeutic remission of chronic alcoholism without complete restoration of its symptoms indicates failure of therapeutic remission (FTR). A method was suggested to detect FTR by enzymic activity of gamma-glutamyltranspeptidase, aspartate transaminase, alanintransaminase and glutamate dehydrogenase. FTR is stated at differential threshold of the above enzymes 32, 25, 26 and 6.5 u/l, respectively. Validity of the method was confirmed at examination of 110 chronic alcoholics and 61 healthy persons. Early FTR detection prevents occurrence of true recurrence of chronic alcoholism.

Adult↗
PubMedDate not supplied

[Temporal resolving capacity of the auditory analyzer of the dolphin Tursiops truncatus].

Differential threshold of discrimination of paired stimuli in relation to interimpulse interval has been investigated in man and porpoise. Similar features in mechanisms of discrimination of paired impulses in man and porpoise are noted. It was shown that threshold-interimpulse interval surve may be divided into several parts: two zones in which discrimination is made by different characters, and single transitional zone from one character to another.

Animals↗
PubMed1997

Intra-operative electrocochleography in stapedectomy and ossicular reconstruction.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of intraoperative electrocochleography (ECOG) in predicating the postoperative hearing improvement in surgery for conductive hearing loss. STUDY DESIGN: This study was a prospective study of 22 patients undergoing intraoperative electrocochleography during a stapedectomy. SETTING: The study was performed in a tertiary referral center. PATIENTS: Intraoperative electrocochleography was performed in 22 patients 27-73 years of age undergoing a stapedectomy for otosclerosis under general anesthesia. INTERVENTION: For each patient, the N1 threshold to click stimulation was measured intraoperatively, before and after the reconstruction. MAIN OUTCOME MEASURES: The intraoperative ECOG thresholds were compared with the pre and postoperative audiograms. RESULTS: Postreconstruction ECOG's demonstrated improvements in the N1 threshold in 19 cases, and were unchanged in 1 case. In each of these cases, improvement in the intraoperative N1 threshold corresponded with improvement in the postoperative audiogram compared with the preoperative studies. In two other cases the postreconstruction ECOG was nearly unobtainable, despite improved hearing postoperatively. CONCLUSION: Intraoperative ECOG appears to be an effective tool for verifying the functional integrity of ossicular reconstructions as in stapedectomies. We speculate that intraoperative ECOG may allow the surgeon to "fine tune" the reconstruction to optimize the hearing results.

Adult↗
PubMed1998

Transient frequency and intensity sensitivities of central auditory neurons determined with sweep tone.

To determine the transient frequency and intensity sensitivities of central auditory neurons, we implemented an exponential sweep tone stimulus (2 sec in period, mean sweep rate 3.3 octave/sec), intensity of which varied systematically across trials. Response of single units to the stimulus was studied at the inferior colliculus (IC) of urethane-anesthetized rats. Most IC units responded to the sweep tone by one or more transient increases in discharge rate. The area of increased discharge, or response area (RA), was delineated on the frequency-intensity plane. The tip of RA gives the best frequency (BF) and minimum threshold (MT) of the cell. We also compared the BF and MT concurrently obtained with another method, viz., the conventional 'audio-visual' method of subjective judgment. Results showed that for the same population of cells (n=130), correlation between the two methods is better for BF (r=0.91) than for MT (r=0.78). Such discrepancy was discussed in relation to the response characteristics of these central auditory neurons.

Acoustic Stimulation↗
PubMed2005

Distortion product otoacoustic emissions for hearing threshold estimation and differentiation between middle-ear and cochlear disorders in neonates.

Our aim in the present study was to apply extrapolated DPOAE I/O-functions [J. Acoust. Soc. Am. 111, 1810-1818 (2002); 113, 3275-3284 (2003)] in neonates in order to investigate their ability to estimate hearing thresholds and to differentiate between middle-ear and cochlear disorders. DPOAEs were measured in neonates after birth (mean age = 3.2 days) and 4 weeks later (follow-up) at 11 test frequencies between f2 = 1.5 and 8 kHz and compared to that found in normal hearing subjects and cochlear hearing loss patients. On average, in a single ear hearing threshold estimation was possible at about 2/3 of the test frequencies. A sufficient test performance of the approach is therefore suggested. Thresholds were higher at the first measurement compared to that found at the follow-up measurement. Since thresholds varied with frequency, transitory middle ear dysfunction due to amniotic fluid instead of cochlear immaturity is suggested to be the cause for the change in thresholds. DPOAE behavior in the neonate ears differed from that found in the cochlear hearing loss ears. From a simple model it was concluded that the difference between the estimated DPOAE threshold and the DPOAE detection threshold is able to differentiate between sound conductive and cochlear hearing loss.

Acoustic Stimulation↗
PubMed2004

Where to set the threshold between well differentiated and poorly differentiated follicular carcinomas of the thyroid.

A critical review of the literature reveals that different types of thyroid carcinomas have been interpreted as poorly differentiated, including the tall and columnar cell variants as well as carcinomas with insular, trabecular, and solid growth patterns. In some publications the growth patterns have been emphasized, while in others histologic patterns and cytologic features are considered important for identification. However, insular, trabecular, nodular, and solid growth patterns lack specificity because they can be observed in hyperplastic lesions and benign thyroid tumors. The cytologic features of the vast majority of poorly differentiated thyroid carcinomas are similar to or overlap with those of papillary or follicular carcinomas. Cytologic atypia, mitotic activity, and necrosis--believed by some investigators to be useful clues in the diagnosis of poorly differentiated carcinomas--do not reflect cell differentiation, especially in endocrine organs. It is therefore not surprising that the immunohistochemical profile and the molecular abnormalities described in this heterogeneous group of carcinomas lack specificity and are not useful diagnostic tools. Because poorly differentiated thyroid carcinomas have not been well defined, currently it is not possible to set the threshold between well-differentiated and poorly differentiated thyroid carcinomas with follicular phenotype. The authors believe that the vast majority of poorly differentiated thyroid carcinomas are in fact examples of papillary or follicular carcinomas with unusual growth patterns.

Adenocarcinoma, Follicular↗