Biomedical subjects

M Ayalon

Publications and source records attributed to M Ayalon.

7 recordsLinked to original sources

PubMed2000

Reliability of isokinetic strength measurements of the knee in children with cerebral palsy.

This study evaluates the reliability of isokinetic testing of the knee flexors and extensors in children with cerebral palsy (CP). Twelve children (seven girls, five boys), aged 9 to 15 years, participated in this study. The children's strength was measured bilaterally, using a dynamometer. Each participant was tested twice at an interval of 1 week. During each session, the participant performed five consecutive cycles of knee extension and flexion. Testing velocity was set at 90 degrees/s, and the range of motion was 80 degrees, starting with the knee flexed at 80 degrees and ending in full extension. The measured variable was the peak torque. Reliabilities were determined using intraclass coefficient (ICC) with two-way ANOVA model. The ICCs for individual sessions range from 0.90 to 0.99. ICCs for the eight repetitions over the two sessions range from 0.95 to 0.98. The findings indicate that measuring isokinetic strength in the tested population is highly reliable and should be considered in rehabilitation protocols.

Adolescent↗

PubMed2000

Isokinetic strength and endurance of the knee extensors and flexors in trans-tibial amputees.

Significant levels of muscular fatigue alter the co-ordination patterns and the ability to accomplish proper daily functions, especially in patients with initial low levels of strength. The purpose of this study was to evaluate the strength and endurance of the quadriceps and hamstring muscles in trans-tibial amputees. Concentric strength and endurance of the thigh muscles were measured bilaterally by an isokinetic dynamometer. The measured variables were torque and angle. For the endurance test, a fatigue index was calculated. Peak torque for extension and flexion was significantly higher in the sound limb (p<0.01). The fatigue index for extension was not significantly different in the sound limb from the amputated limb. The fatigue index for flexion is significantly higher in the sound limb (p<0.01). The finding may imply that from a metabolic point of view, the muscles of the amputated limb function properly. It is of great importance to reduce the bilateral deficit and the degree of atrophy as soon as possible in order to improve the level of performance. By choosing a correct strength and endurance training programme, one may expect to get a significant and good reaction from the muscles of the amputated limb as is expected from training the muscles of a sound limb.

Adaptation, Physiological↗

PubMed1997

Endoplasmic reticulum quality control of asialoglycoprotein receptor H2a involves a determinant for retention and not retrieval.

The human asialoglycoprotein receptor H2a subunit contains a charged pentapeptide, EGHRG, in its ectodomain that is the only sequence absent from the H2b alternatively spliced variant. H2b exits the endoplasmic reticulum (ER) even when singly expressed, whereas H2a gives rise to a cleaved soluble secreted ectodomain fragment; uncleaved membrane-bound H2a molecules are completely retained and degraded in the ER. We have inserted the H2a pentapeptide into the sequence of the H1 subunit (H1i5), which caused complete ER retention but, unexpectedly, no degradation. This suggests that the pentapeptide is a determinant for ER retention not colocalizing in H2a with the determinant for degradation. The state of sugar chain processing and the ER localization of H1i5, which was unchanged at 15 degrees C or after treatment with nocodazole, indicate ER retention and not retrieval from the cis-Golgi or the intermediate compartment. H1i5 folded similarly to H1, and both associated to calnexin. However, whereas H1 dissociated with a half time of 45 min, H1i5 remained bound to the chaperone for prolonged periods. The correct global folding of H2a and H1i5 and of other normal precursors and unassembled proteins and the true ER retention, and not exit and retrieval, suggest a difference in their quality control mechanism compared with that of misfolded proteins, which does involve retrieval. However, both pathways may involve calnexin.

3T3 Cells↗

PubMed1996

Membrane-bound versus secreted forms of human asialoglycoprotein receptor subunits. Role of a juxtamembrane pentapeptide.

The H2a alternatively spliced variant of the human asialoglycoprotein receptor H2 subunit differs from the H2b variant by an extra pentapeptide, EGHRG, present in the ectodomain next to the membrane-span. This difference causes retention and degradation in the endoplasmic reticulum (ER) of H2a when expressed without the H1 subunit in 3T3 cells. In contrast, a significant portion of singly expressed H2b is Golgi-processed and reaches the cell surface. Using a new specific anti-H2a antibody, we found that in HepG2 cells, H2a is rapidly cleaved to a 35-kDa fragment, comprising the entire ectodomain, most of which is secreted into the medium. The cleavage site for the secreted fragment was located at the lumenal end of the membrane span. No membrane-bound H2a exits the ER, indicating that the pentapeptide is a signal for ER retention and degradation of the membrane form but does not hinder secretion of the cleaved soluble form. H2a does not form a membrane receptor complex with H1 as H2b does. H2a is therefore not a subunit of the receptor but a precursor for a secreted form of the protein; signal peptidase is probably responsible for the cleavage to the soluble fragment. Therefore, the juxtamembrane sequence regulates the function of the transmembrane domain of a type II membrane protein as either a signal-anchor sequence (H2b) or as a cleaved signal sequence, which generates a secreted product (H2a).

3T3 Cells↗

PubMed1986

Bone marrow transplantation with T-cell-depleted grafts. I. Reconstitution of immunohemopoietic functions in lethally irradiated mice transplanted with unseparated or T-cell-depleted syngeneic bone marrow grafts.

The potential role of donor's mature T lymphocytes on the recovery of various immunological functions and hematopoiesis was investigated in lethally irradiated BALB/c mice by studying reconstitution with normal, as compared with T-cell-depleted, syngeneic marrow grafts. Recovery of total, as well as mononuclear, peripheral white blood cell counts, platelets, hemoglobin levels, proportion of Thy 1.2+ cells, responses to concanavalin A, phytohemagglutinin and lipopolysaccharide, mixed lymphocyte response, cell-mediated lympholysis response, anti-SRBC agglutinins and natural killer activity were basically similar in recipients of unmanipulated (as compared with T cell depleted) syngeneic marrow grafts. The data suggest that in a syngeneic murine bone marrow transplantation setting, mature donor T lymphocytes do not seem to play a major role in immunohemopoiesis. Normal T cell number and T-cell-dependent immune function can be readily regenerated out of the stem cell reservoir of adult donors following transplantation into lethally ablated recipients.

Animals↗

PubMed1985

The teacher interview.

The teachers and caretakers (on kibbutzim) of the index and control children were questioned about a variety of behaviors, including emotional adjustment, school performance and achievement, interests and activities, and relations with others. Index children were rated as more impaired or disturbed than control subjects in the following areas: schoolwork, mood, suspiciousness, daydreaming, antisocial behavior, hypochondriasis, and accident proneness. No differences were seen in anxiety, aggression, phobias, obsessive-compulsive behavior, eating and sleep disturbances, shame, and frustration tolerance. There were few differences between assessments of index and control children on kibbutzim and towns. Male index subjects tended to be seen as especially poorly adjusted.

Achievement↗

PubMed1985

Clinical-subjective evaluation of high-risk children: integration and discussion.

Clinical evaluations of index and control children from the point of view of the clinical interview, observations of the subjects during testing, the subjects' parents, and their teachers were compared. There was general agreement that index children showed more psychopathological symptoms, poorer ego development, poorer interpersonal relations, and poorer use of leisure time than their controls. By contrast, behaviors related to aggression, phobias, shame, sleep pathology, eating disorders, frustration tolerance, sexual behavior, and verbal communication skills failed to show consistent group differences. Index boys showed greater anxiety than their controls, while there were no such differences among the girls. Rearing environment exerted no apparent effect on the psychosocial functioning of the children. Factor analysis disclosed that a general factor, accounting for 32.6 percent of the variance, discriminated between index and control children, while several special factors, which represented rarely seen traits, did not discriminate. Group differences, therefore, appeared to stem from global impairment of psychosocial functioning rather than from several distinct patterns of deficit. The present results are in general agreement with previously reported evaluations of children at risk for schizophrenia.

Adaptation, Psychological↗