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PubMed2005

Method to compare mu-tensile bond strength of a self-etching adhesive and mu-cohesive strength of adjacent dentin.

UNLABELLED: Laboratory results from tensile or micro-tensile testing of adhesive/restorative systems need a gold standard to make their interpretation possible. This can be done by comparing the mu-tensile bond strength (muTBS) of the tested adhesive(s) with the mu-tensile cohesive strength (muTCS) of the adjacent dentin, which is meant to be replaced by the restoration. OBJECTIVES: To test immediate muTBS of an adhesive/restorative system versus muTCS of the dentin adjacent to the bonded interface, in perfused specimens. METHODS: Enamel and roots of five-third sound molars were removed and teeth were perfused (30 cm distilled H2O) until after the bonding procedure was completed. Parallel grooves (1.5-mm widex 1.5-mm deep, separated by 1.5mm), were drilled in the exposed dentin, under water refrigeration. Teeth were restored (AdheSE/Filtek Z250). Specimens were sawn from grooves to test muTBS (n = 30) and from between grooves to test muTCS (n = 32) of dentin, adjacent to adhesive interfaces, both areas to be tested at the same relative depth. Areas to be studied were rounded (mean bonded surface area for both groups, BA = 0.68 mm2), and muTBS and muTCS were found. As not all BAs were identical, residuals of muTBS and muTCS values to the regression line relating BA and tensile test results (representing the null hypothesis, i.e. muTBS = muTCS) were compared using a non-parametric test. RESULTS: Difference in the means of residuals was not statistically significant (two tails p = 0.067). SIGNIFICANCE: mean muTBS of the tested adhesive was not different to mean muTCS of adjacent dentine. The null hypothesis was not rejected.

Acrylic Resins↗
PubMedDate not supplied

Effect of re-using nickel-chromium alloy on its ultimate tensile strength, yield strength and modulus of elasticity.

In order to bring down the cost of the castings used in fixed partial denture prosthesis, a study was conducted by reusing the nickel chromium alloy without adding any new material. We studied the effect on the ultimate tensile strength, yield strength and modulus of elasticity after reusing the nickel-chromium alloys. Results showed degenerative changes in the properties evaluated after recasting. These changes were statistically significant, suggesting that it can not be reused.

Chromium Alloys↗
PubMed1989

[Testing metal/acrylic bonds for shear strength, axial tensile strength and maximum bending stress].

The effects of thermocycling and water penetration on the bond strength of resin-metal-systems and improvements using bonding agents have been tested by shear, bending and tensile tests. After 10,000 cycles within 10 days in different water-baths with 5-37-55 degrees C, there is a decrease in bond strength by 40 to 60%. The use of bonding agents increases the adhesion of the resin to the metal by more than 100%. No significant differences were found between the three bonding agents Silicoater, Sebond MKV and OVS.

Acrylic Resins↗
PubMed1982

Heritabilities of ego strength (factor C), super ego strength (factor G), and self-sentiment (factor Q3) by multiple abstract variance analysis.

Tested over 3,000 boys (identical and fraternal twins, ordinary sibs, general population) aged 12-18 on Ego Strength, Super Ego Strength, and Self Sentiment. The Multiple Abstract Variance Analysis (MAVA) method was used to obtain estimates of abstract (hereditary, environmental) variances and covariances that contribute to total variation in the three traits. Within-family heritabilities for these traits were about .30, .05, and .65. Between-family heritabilities were .60, .08, and .45. Within-family correlations of genetic and environmental deviations were trivial, unusually so among personality variables, but between-family values showed the usual high negative values, consistent with the law of coercion to the biosocial mean.

Adolescent↗
PubMedDate not supplied

Bone mineral density and muscle strength of lower extremities after long-term strength training, subsequent knee ligament injury and rehabilitation: a unique 2-year follow-up of a 26-year-old female student.

Physical training is shown to have potential to increase the mass of healthy bones. In contrast, immobilization, used as a treatment of soft tissue and bone injuries, is shown to result in atrophy of these tissues. In this unique 26-month follow-up of a 26-year-old female student, we determined the effects of a 1-year strenuous unilateral lower limb strength training and subsequent anterior cruciate ligament (ACL) rupture on bone mineral density (BMD) of lumbar spine and lower extremities (femoral neck, distal femur, patella, proximal tibia, calcaneus), measured repeatedly (11 times) by dual-energy X-ray absorptiometry (DXA). Also, the strength and functional characteristics of the lower extremities were repeatedly examined. This prospective study strikingly demonstrated the deleterious effects of an ACL rupture on the BMD of the affected limb in contrast to beneficial but modest effects of the preceding controlled training. The site-specific increases in the BMD were 1.8-3.1% during the training. The posttraumatic decrease in the BMD of the injured knee was rapid and corresponded to approximately 2 SD (approximately 20%) observed in the age- and sex-matched population. A year after the injury, the subject's knee function and muscular performance as well as the usage of the injured limb were completely recovered, but the site-specific BMDs were still approximately 1 SD below the subject's baseline BMD, although continuously increasing. This study suggests that considerable posttraumatic osteopenia at the affected bone sites occurs quickly regardless of appropriate preventive and rehabilitative actions, and the time needed for steady-state and recovery will be long.(ABSTRACT TRUNCATED AT 250 WORDS)

Absorptiometry, Photon↗
PubMedDate not supplied

Individual V(H) promoters vary in strength, but the frequency of rearrangement of those V(H) genes does not correlate with promoter strength nor enhancer-independence.

The process of V(D)J recombination is highly regulated. Germline transcription of unrearranged gene segments precedes V(D)J rearrangement, and the correlation between germline transcription and accessibility for recombination is strong; thus it has been suggested that germline transcription may be required for rearrangement. If germline transcription is essential for rearrangement, then the level of transcription of individual gene segments might affect the relative frequency of recombination of those genes. Also, since the intronic enhancer, E(mu), is very distant from V(H) genes before they rearrange, then any promoters which were enhancer dependent might have a transcriptional advantage. Here we study in luciferase vectors the promoters of three functional genes of the V(H)S107 family, and compare them to that of the most frequently rearranging gene in the mouse I(g)H locus, V(H)81X, and to a V(H)J558 gene. Within the V(H)S107 family, the three V(H) genes rearrange with very different relative frequencies, with V1 rearranging the most, and V13 seldom rearranging. We show that only the strong V(H)J558 promoter has significant luciferase reporter gene activity in the absence of E(mu). V1 has only 20% as much activity as J558 in the absence of E(mu), and the other promoters have less than 8% of the activity of J558. Notably, the 81X promoter has essentially no enhancer-independent activity. In the presence of E(mu), V1 has equivalent activity to J558, while the other promoters show much less activity. Again, 81X is the weakest promoter of all, despite being the most frequently rearranging gene. Finally, we show that the steady state level of V(H)S107 and V(H)7183 germline transcripts in vivo is very low. Thus, these data show little correlation between the strength or enhancer-independence of these V(H) promoters and the relative frequency of recombination of the corresponding V(H) genes. In addition, the data show that individual V(H) promoters have different strengths even in the presence of E(mu), demonstrating that even promoters within a single V(H) family can be quite heterogeneous.

Animals↗
PubMed2003

Recovery of skeletal muscle contractility and hormonal responses to strength exercise after two weeks of high-volume strength training.

Exercise induced neuromuscular fatigue, recovery and hormonal responses were studied before (R1) and after (R2) 2 weeks of heavy strength training. Seventeen weight-trained male students were recruited into a heavy training group (HT, n = 10) and a control group (n = 7). During heavy training HT exercised leg extensors every day while control group exercised twice a week. Test workouts (R1 and R2) were used to induce neuromuscular fatigue and hormonal responses. Acute fatigue after the test workouts was reduced after heavy training in the HT group (P < 0.05) but not in the control group. Twenty-two hrs after the test workouts recovery from fatigue was not complete before heavy training, but recovery was complete after heavy training in both groups. The relative change in exercise induced cortisol and GH response, from before to after heavy training, was significantly different between groups, but for both hormones alterations in the control groups response was responsible for the between groups difference. IGF-1 concentration was reduced 22 h after the test workout performed after heavy training in the HT group (P < 0.05). In conclusion, two weeks of high volume strength training attenuated neuromuscular fatigue after a test workout with only minor changes in exercised induced hormone response.

Adult↗
PubMedDate not supplied

[Implant fixation strength and osseointegration following systemic administration of recombinant factor XIII and factor XIII concentrate. Animal experiment with implant fixation strength and osseointegration of porous surface implants].

30 cylindrical commercially pure titanium fiber porous coated Ti6A14V implants were inserted press-fit into the proximal humeral portion of 30 sheep humeri to determine the systemic effect of recombinant factor XIII and placenta-derived factor XIII concentrate on bone ingrowth and on strength of fixation. For both the recombinant factor XIII and the factor XIII concentrate group the volume fraction of bone ingrowth and the strength of fixation was higher when compared with the control specimens. However the difference was only significant for the factor XIII concentrate group.

Alloys↗
PubMed1993

Isokinetic trunk strength and lifting strength measures. Differences and similarities between low-back-injured and noninjured workers.

Fifty-eight back pain patients and 21 entry-level Postal Service workers without low-back pain were evaluated using a variety of lumbar function measures. Isolated trunk strength and full lifting strength were gauged with isokinetic and isometric methods. Lumbar range-of-motion was computed using toe-touch and goniometers. Conventional clinical techniques such as toe touch and straight leg raise were effective in distinguishing back-injured from normal subjects. Isometric and isokinetic peak force and torque tests failed to show significant differences between low-back pain and job applicant groups. When compared with published norms, our job applicant group was significantly deconditioned. Our data suggest that asymptomatic, deconditioned subjects could be mistaken for back-impaired patients or symptom magnifiers.

Adult↗
PubMed1988

Comparison between a solid-phase low-ionic-strength solution antiglobulin test and conventional low-ionic-strength antiglobulin test: assessment for the screening of antierythrocyte antibodies.

A solid-phase low-ionic strength salt antiglobulin test (LISS-SPAT) has been developed using a microplate coated with dried sera as a solid phase. Before coating, the in vitro C3d fragment generation was activated by adding heat-aggregated immunoglobulin. The LISS-SPAT was compared with low-ionic strength conventional antiglobulin test (LISS-AGT) and also with a test using polybrene or papain microplates. When detecting the IgG and IgM antierythrocyte antibodies the reaction was developed in the same way in LISS-SPAT and LISS-AGT. In routine work, the LISS-SPAT provides a fast, reliable, handy and inexpensive screening of antibodies. This method appears to be an additional method to the papain and polybrene tests in microplates.

Blood Group Antigens↗
PubMed2004

Human jaw muscle strength and size in relation to limb muscle strength and size.

The aim of the present study was to investigate to what extent general factors (e.g. genotype, hormones) and factors at the craniofacial level (e.g. craniofacial size, jaw muscle architecture) contribute to the size and strength of the jaw muscles. A strong relationship of jaw muscle size and strength with that of other muscles would argue for general influences, whereas a weak relationship would argue for craniofacial influences. In 121 adult individuals, moments of maximal bite force, arm flexion force and leg extension force were measured. In addition, thicknesses of jaw muscles, arm flexor muscles and leg extensor muscles were measured using ultrasound. Relationships were assessed by using a principal component analysis. In females, one component was found in which all force moments were represented. Bite force moment, however, loaded very low. In males, two components were found. One component loaded for arm flexion and leg extension moments, the other loaded for bite force moments. In both females and males, only one component was found for the muscle thicknesses in which all muscle groups loaded similarly. It was concluded that the size of the jaw muscles was significantly related to the size of the limb muscles, suggesting that they were both subject to the same general influences. Maximal voluntary bite force moments were not significantly related to the moments of the arm flexion and leg extension forces, suggesting that besides the general influence on the muscle size, variation in bite force moment was also influenced by local variables, such as craniofacial morphology.

Adolescent↗
PubMed2004

Strength and conditioning practices of National Hockey League strength and conditioning coaches.

This study describes the results of a survey of the practices of National Hockey League strength and conditioning (NHL S&C) coaches. The response rate was 76.6% (23 of 30). This survey examines (a) background information, (b) physical testing, (c) flexibility development, (d) speed development, (e) plyometrics, (f) strength/power development, (g) unique aspects, and (h) comments. Results indicate, in part, that coaches assess an average of 7.2 parameters of fitness, with tests of strength and power being the most common. All coaches used a variety of flexibility-development strategies. Results reveal that 21 of 23 (91.3%) of NHL S&C coaches follow a periodization model (PM). Of the coaches who follow a PM, 21 of 21 (100%) indicated that their athletes used Olympic-style lifts, and 21 of 21 coaches (100%) trained athletes with plyometric exercises. For those who used plyometrics with their athletes, 17 of 21 (80.1%) reported no plyometric-related injuries in the past year. Coaches who report they did not follow a PM also did not use Olympic-style lifts, plyometrics, or speed development strategies, such as assisted, resisted, or interval training, with their athletes. Finally, coaches reported that the squat and their variations, as well at the Olympic-style lifts and its variations, were most frequently used with their athletes. The survey serves as a review, as well as a source of applied information and new ideas.

Hockey↗
PubMed2005

Strength and conditioning practices of Major League Baseball strength and conditioning coaches.

This study describes the results of a survey of the practices of Major League Baseball strength and conditioning (MLB S&C) coaches. The response rate was 70.0% (21 of 30). This survey examines (a) background information, (b) physical testing, (c) flexibility development, (d) speed development, (e) plyometrics, (f) strength/power development, (g) unique aspects, and (h) comments. Results indicate, in part, that coaches assess an average of 3.6 parameters of fitness, with body composition testing being the most commonly assessed parameter. All coaches use a variety of flexibility development strategies. All coaches use speed development strategies, with form running drills being the most common. Twenty of 21 (95.2%) coaches employ plyometric exercises with their athletes. Eighteen of 21 (85.7%) of MLB S&C coaches follow a periodization model (PM). Five of 21 coaches (23.8%) indicated that their athletes use Olympic-style lifts. The squat and its variations and the lunge and its variations were most frequently identified as the first and second most important exercises used to train the athletes. This survey provides detailed information about strength and conditioning practices at the most competitive level of baseball and serves as a review, as well as a source of applied information and new ideas.

Baseball↗
PubMed1978

Studies on mechanical strength of bone. II. Torsional strength of cortial bone after rigid plate fixation with and without compression.

Biomechanical properties of intact rabbit tibio-fibulae were investigated with torional loading 1 day to 36 weeks after fixation using 4-hole stainless steel ASIF/DCP plates with and without compression. During the first 12 weeks energy absorption and torque moment increased slightly as a result of subperiosteal new bone formation following application of the plates. There was a concomitant increase in the yielding properties of the bone, reflecting progressive porotic transformation. Thereafter, up to 36 weeks postoperatively, the values for energy absorption, torque moment and angular deformation gradually declined in both groups of bones. The differences between normal control bones and plated bones at 36 weeks were 70.1, 53.0 and 26.3 per cent, respectively. The decay of torsional strength was the same whether or not compression was used in the plate fixation. The results suggest that even in normal bone rigid plates induce a considerable loss of strength due to the cancellous transformation they are known to cause in cortical bone.

Animals↗
PubMed2001

Strength and conditioning practices of National Football League strength and conditioning coaches.

This article describes the results of a survey of the practices of National Football League strength and conditioning (NFL S&C) coaches. The response rate was 87% (26 of 30). This survey examines survey participant (a) background information, (b) physical testing, (c) flexibility development, (d) speed development, (e) plyometrics, (f) strength/power development, (g) unique aspects, and (h) comments. Results reveal that 18 of 26 (69%) NFL S&C coaches follow a periodization model (PM). Of these coaches, 14 of 16 (88%) who responded to the question reported their athletes used Olympic-style lifts, and 17 of 18 coaches (94%) employed plyometric exercises. Coaches who reported following a PM tested an average of 9.8 variables of fitness, which is an average of 3.55 times per year. Seven of 26 (27%) NFL S&C coaches did not follow a PM (NPM). Five of 7 (71%) of these coaches reported following "high-intensity training" (HIT) principles. None of these coaches reported using Olympic-style lifts. Two of 7 (29%) reported using plyometrics. NFL S&C coaches who follow an NPM reported testing an average of 2.12 variables of fitness, which is an average of 2 times per year. A variety of other strength and conditioning practices were examined.

Adaptation, Physiological↗
PubMed2001

[Measuring grip strength of the hand with a sensor glove by gripping with submaximal and maximal strength].

Grip strength measurements with the aid of dynamometers are dependent on the cooperation and motivation of the individual examined. Recognising a simulated loss of grip is a hitherto unresolved problem. With a sensor glove developed at the Berlin University of Technology, the force distribution pattern of any form of grip can be captured via ten pressure sensors and evaluated by computer. In five subjects, the force distribution patterns at submaximum and maximum force of five different grips were determined in three successive measurements each. The data were recorded in force-time diagrams. For each act of grasping, the measurements produced a curve with near-constant measuring signals within a defined period (plateau). The difference in the plateau heights of successive grips and the structures of the individual plateaux (oscillation, standard deviation) were used as distinguishing criteria. The dynamics of the measuring signals showed statistically significant differences between grips with submaximum and maximum force (p < 0.0001).

Adult↗
PubMed1992

Ego-strength revised: a comparison of the MMPI-2 and MMPI-1 versions of the Barron Ego-strength scale.

This study evaluated the equivalence of the original MMPI and the shortened MMPI-2 versions of the Barron (1953) Ego-strength scale, an important research scale. Three hundred fifty-five subjects took the MMPI-2 and the 16 MMPI-1 items dropped from the original scale. The omitted items appear to contribute little to the original scale. The revised version compares favorably with the old in terms of internal consistency, and the two versions are highly intercorrelated. Confirmatory Factor Analysis indicates that four of Stein and Chu's (1967) five groupings of the original items provide a reasonably good fit for the MMPI-2 as well. Compared to the original, the new version was slightly more correlated with other paper-and-pencil measures of psychological health and well-being.

Ego↗