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Biomedical subjects

A P Hollander

Publications and source records attributed to A P Hollander.

At least 19 recordsLinked to original sources
PubMed2006

The individual relationship between heart rate and oxygen uptake in people with a tetraplegia during exercise.

STUDY DESIGN: Descriptive study. OBJECTIVE: To examine the individual heart rate-oxygen uptake (HR-VO(2)) relationship during exercise in persons with tetraplegia (TP). SETTING: Rehabilitation Centre Heliomare, Wijk aan Zee, The Netherlands. METHODS: The HR-VO(2) relationship was determined in untrained subjects with motor complete TP (C5 or C6, n=10 and C7 or C8, n=10) during a discontinuous graded exercise hand cycle test. The mean HR and VO(2) of the final 60 s of 2-min exercise blocks were used for calculation of the individual correlation coefficient and the standard error of the estimate (SEE). RESULTS: Two subjects of the C5-C6 group were not able to complete the test. Individual Pearson's correlation coefficients (r) ranged from 0.68 to 0.97 and SEE from 2.6 to 22.4% VO(2)-Reserve (VO(2)R). The mean Pearson's r and SEE were 0.81+/-0.12 and 10.6+/-5.6% VO(2)R in the C5-C6 group and 0.91+/-0.07 and 7.0+/-3.2% VO(2)R in the C7-C8 group, respectively. Two subjects of the C5-C6 group and six subjects of the C7-C8 group attained a linear HR-VO(2) relationship with an acceptable SEE (< or =6.0%) and r (>0.90). CONCLUSIONS: The HR-VO(2) relationship appeared linear in only eight out of 18 subjects. An individual analysis of the HR-VO(2) relationship is necessary to determine whether HR can be used to quantify exercise intensity. The use of HR to prescribe training intensity should be reconsidered in persons with TP. SPONSORSHIP: This study is supported from a grant by ZON-MW.

Adult↗
PubMed2006

Cartilage tissue engineering by expanded goat articular chondrocytes.

In this study we investigated whether expanded goat chondrocytes have the capacity to generate cartilaginous tissues with biochemical and biomechanical properties improving with time in culture. Goat chondrocytes were expanded in monolayer with or without combinations of FGF-2, TGF-beta1, and PDGFbb, and the postexpansion chondrogenic capacity assessed in pellet cultures. Expanded chondrocytes were also cultured for up to 6 weeks in HYAFF-M nonwoven meshes or Polyactive foams, and the resulting cartilaginous tissues were assessed histologically, biochemically, and biomechanically. Supplementation of the expansion medium with FGF-2 increased the proliferation rate of goat chondrocytes and enhanced their postexpansion chondrogenic capacity. FGF-2-expanded chondrocytes seeded in HYAFF-M or Polyactive scaffolds formed cartilaginous tissues with wet weight, glycosaminoglycan, and collagen content, increasing from 2 days to 6 weeks culture (up to respectively 2-, 8-, and 41-fold). Equilibrium and dynamic stiffness measured in HYAFF M-based constructs also increased with time, up to, respectively, 1.3- and 16-fold. This study demonstrates the feasibility to engineer goat cartilaginous tissues at different stages of development by varying culture time, and thus opens the possibility to test the effect of maturation stage of engineered cartilage on the outcome of cartilage repair in orthotopic goat models.

Animals↗
PubMed2005

Human nasal cartilage responds to oncostatin M in combination with interleukin 1 or tumour necrosis factor alpha by the release of collagen fragments via collagenases.

BACKGROUND: The synergistic degradation of cartilage by oncostatin M (OSM) in combination with either interleukin 1 (IL1) or tumour necrosis factor alpha (TNFalpha) has been previously demonstrated using bovine nasal cartilage (BNC). OBJECTIVES: (a) To investigate if human nasal cartilage (HNC) responds in the same way as BNC to these cytokine combinations, particularly in collagen degradation. (b) To compare the response of human nasal and articular cartilages. METHODS: Collagen release was assessed by measuring the hydroxyproline content of culture supernatants and proteoglycan release by the dimethylmethylene blue assay. Matrix metalloproteinase (MMP)-1, MMP-13, and tissue inhibitor of metalloproteinase 1 release were measured by specific enzyme linked immunosorbent assays (ELISAs), and collagenolytic activity was measured by a bioassay using radiolabelled collagen. RESULTS: OSM in combination with either IL1 or TNFalpha acted synergistically to induce collagenolysis from HNC, with a maximum of 79% collagen release. This degradation strongly correlated with MMP-1 and MMP-13 levels and collagenolytic activity. CONCLUSION: Collagen release from human cartilage is marked and implicates both MMP-1 and MMP-13 in the synergistic degradation of human cartilage by OSM in combination with either IL1 or TNFalpha. HNC responds in the same way as BNC, thus validating the bovine cartilage degradation assay as a model relevant to human disease.

Adult↗
PubMed2005

Influence of task complexity on mechanical efficiency and propulsion technique during learning of hand rim wheelchair propulsion.

OBJECTIVE: To investigate the consequence of task complexity on gross mechanical efficiency and propulsion technique during the learning process of hand rim wheelchair propulsion. METHODS: Three groups of unimpaired subjects (N=10 each) received a 3-week wheelchair practice period (3 week(-1), nine practice trials) with different levels of complexity, i.e. propelling a stationary wheelchair ergometer, wheelchair propulsion on a motor-driven treadmill or at a circular wheelchair track. During practice trials 1 and 9, gross mechanical efficiency and propulsion technique variables (work per cycle, cycle frequency, push and cycle time, effective force) were measured. RESULTS: Using multi-level regression analysis, no differences in the development over time in mechanical efficiency and propulsion technique could be discerned between the three conditions of task complexity. Only the percentage push time during the cycle decreased significantly more in the group that practiced on the ergometer compared to the treadmill-practice group. For all three groups a change over time was shown for cycle frequency, push time and cycle time. DISCUSSION: Under the current experimental conditions, task complexity does not have an influence on gross mechanical efficiency and propulsion technique during the learning process of wheelchair propulsion. The 3-week practice period had a favorable practice effect on timing regardless of the task complexity.

Adaptation, Physiological↗
PubMed2004

Effect of matrix depleting agents on the expression of chondrocyte metabolism by equine chondrocytes.

This study was carried out to investigate the effect of two enzymes (collagenase and chondroitinase) and two cytokines/metabolites (interleukin-1beta and retinoic acid) of known catabolic activity on the expression of cartilage metabolism/phenotype in equine articular cartilage. Articular cartilage explants from 11 horses (5-13 years old) were treated for 48 h and assayed for total sulphated glycosaminoglycan (GAG), the incorporation of 35S-sulphate, collagen degradation and mRNA expression of the proteoglycans collagen II, collagen IIA, collagen III, collagen IX, collagen X, collagen XI and glyceraldehyde-3-phosphate (GAPDH). Purified collagenase and retinoic acid were responsible for increased GAG loss from the tissues. Chondroitinase, responsible for catalysing the elimination of glucuronate residues from chondroitin A, B and C (Chondroitinase ABC) and retinoic acid treatment induced an inhibition of proteoglycan synthesis, whereas collagenase treatment did not. Collagenase activity was correlated with increased appearance of the CB11B epitope and type II collagen denaturation. By RT-PCR there was evidence of expression of altered collagen type IIA in purified collagenase treated tissues.

Animals↗
PubMed2004

Effect of wheelchair stroke pattern on mechanical efficiency.

OBJECTIVE: To investigate the effect of different wheelchair stroke patterns on efficiency and propulsion technique (force application and timing). DESIGN: Inexperienced, able-bodied subjects were randomly divided into two velocity groups (1.11 m/sec [n = 13] and 1.39 m/sec [n = 11]). An external (medium) load was set at 0.23 N/kg. Subjects performed four 4-min exercise blocks on a wheelchair ergometer. The first block was performed with a freely chosen movement pattern of the hand. Thereafter, the pumping, semicircular, or single-looping over propulsion pattern were performed in a counterbalanced order. Gross mechanical efficiency and propulsion technique variables were measured with Oxycon Alpha and an instrumented wheelchair ergometer. RESULTS: A significant difference was found for mechanical efficiency, with pumping showing the highest efficiency and semicircular the lowest efficiency, regardless of velocity. Timing variables and negative power deflections before and after the push phase showed significant differences between the stroke patterns. CONCLUSIONS: Pumping is the energetically most efficient stroke pattern in contrast to the semicircular pattern in this subject group. Propulsion technique could not explain the difference in efficiency.

Adult↗
PubMed2003

The effects of 11 weeks whole body vibration training on jump height, contractile properties and activation of human knee extensors.

The purpose of the present study was to investigate whether 11 weeks of whole body vibration (WBV) training applied in a way that is commonly seen in practice, i.e. without additional loads, would improve muscle activation and/or contractile properties of the knee extensor muscles and counter movement jump height in healthy subjects. Ten subjects belonging to the experimental group trained three times a week and stood bare-foot with a 110 degrees knee angle on a vibration platform (30 Hz, 8 mm amplitude). They underwent five to eight sets of 1-min vibration with 1 min rest in between. Ten control subjects followed the same training programme but stood (110 degrees knee angle) beside the platform. Before, during and following the training period the subjects were tested. Values [mean (SEM)] obtained in the last test were expressed as percentages of the baseline value and presented for control and experimental groups. Quadriceps femoris isometric muscle force [105.4 (6.2)%, 99.9 (2.0)%; P=0.69], voluntary activation [107.1 (6.0)%, 101.1 (2.3)%; P=0.55] and maximal rate of voluntary force rise [95.4 (6.0)%, 103.3 (7.7)%; P=0.57] did not improve. The maximal rate of force rise during electrical stimulation was increased [102.3 (4.5)%, 123.6 (7.5)%; P=0.02]. Counter movement jump height was not affected by WBV [103.7 (1.8)%, 103.0 (2.8)%; P=0.71]. In conclusion, 11 weeks of standard two-legged WBV training without additional training loads did not improve functional knee extensor muscle strength in healthy young subjects.

Adult↗
PubMed2003

Short-term adaptations in co-ordination during the initial phase of learning manual wheelchair propulsion.

The purpose of this study was to analyse adaptations in kinematics and muscle activity/co-contraction in novice able-bodied subjects during the initial phase of learning hand rim wheelchair propulsion. Nine able-bodied subjects performed three 4-min practice blocks on a wheelchair ergometer. The external power output and velocity were constant for all blocks, respectively 0.25 W x kg(-1) and 1.11 m x s(-1). Electromyography of 16 arm, shoulder, back and chest muscles and kinematics were measured. Some small changes in the segmental movement pattern were seen during the practice period. Moreover, an increase in muscle activity and co-contraction of several muscles was found over time. The hypothesis that subjects instinctively search for an optimum frequency, in which the recovery phase is related to the eigenfrequency of the arms and, therefore, the least muscle activity, could not be supported. Since co-contraction of antagonist pairs remained the same or even increased, the hypothesis that there would be a decrease in muscle co-contraction as a result of practice, was not confirmed. This study was probably too short for the novice subjects to explore this new task of wheelchair propulsion completely and reach an optimum in terms of cycle frequency and muscle activity/co-contraction.

Adult↗
PubMed2003

Adaptations in physiology and propulsion techniques during the initial phase of learning manual wheelchair propulsion.

OBJECTIVE: The purpose of this study was to analyze adaptations in gross mechanical efficiency and wheelchair propulsion technique in novice able-bodied subjects during the initial phase of learning hand-rim wheelchair propulsion. DESIGN: Nine able-bodied subjects performed three 4-min practice blocks on a wheelchair ergometer. The external power output and velocity of all blocks was, respectively, 0.25 W/kg and 1.11 m/sec. Gross mechanical efficiency, force application, timing, and intercycle variability were measured. RESULTS: No change in gross mechanical efficiency was found. However, a decrease in push frequency occurred, which was accompanied by an increase in work per cycle and a decrease in percentage push time. The increase in work per cycle was associated with a higher peak torque. No changes in intercycle variability were visible over time. CONCLUSIONS: The timing variables had already changed during the initial phase of learning manual wheelchair propulsion. However, for other variables, such as force production, gross mechanical efficiency, and intercycle variability, a longer practice period might be necessary to induce a change. The effective force direction seemed to be optimized from the start of the learning process onward.

Adaptation, Physiological↗
PubMed2002

Short-term effects of whole-body vibration on maximal voluntary isometric knee extensor force and rate of force rise.

Whole-Body vibration (WBV) may lead to muscle contractions via reflex activation of the primary muscle spindle (Ia) fibres. WBV has been reported to increase muscle power in the short term by improved muscle activation. The present study set out to investigate the acute effects of a standard WBV training session on voluntary activation during maximal isometric force production (MVC) and maximal rate of force rise (MRFR) of the knee extensors. Twelve students underwent a single standard WBV training session: 5x1 min vibration (frequency 30 Hz, amplitude 8 mm) with 2 min rest in between. During vibration, subjects stood barefoot on the vibration platform with their knees at an angle of 110 degrees. At 90 s following vibration, maximal voluntary knee extensor force was reduced to 93 (5)% [mean (SD), P<0.05] of baseline value and recovered within the next 3 h. Voluntary activation remained significantly depressed (2-4%). Neither the electrically induced MRFR nor voluntary MRFR were significantly affected by WBV. In addition, six WBV training sessions in 2 weeks ( n=10) did not enhance either voluntary muscle activation during MVC [99 (2)% of the baseline value] or voluntary MRFR [98 (9)% of the baseline value]. It is concluded that in the short term, WBV training does not improve muscle activation during maximal isometric knee extensor force production and maximal rate of force rise in healthy untrained students.

Adult↗
PubMed2002

Differences in leg muscle activity during running and cycling in humans.

Delta (delta) efficiency is defined as the ratio of an increment in the external mechanical power output to the increase in metabolic power required to produce it. The purpose of the present study was to investigate whether differences in leg muscle activity between running and cycling can explain the observed difference in delta efficiency between the two activities. A group of 11 subjects performed incremental submaximal running and cycling tests on successive days. The delta efficiencies during running and cycling were based on five exercise stages. Electromyograph (EMG) measurements were made of three leg muscles (gastrocnemius, vastus lateralis and biceps femoris). Kendall's correlation coefficients between the mean EMG activity and the load applied were calculated for each muscle, for both running and cycling. As expected, the mean delta efficiency during running (42%) was significantly greater than that during cycling (25%). For cycling, all muscles showed a significant correlation between mean EMG activity and the load applied. For running, however, only the gastrocnemius muscle showed a significant, but low correlation ( r=0.33). The correlation coefficients of the vastus lateralis and biceps femoris muscles were not significantly different from 0. The results were interpreted as follows. In contrast to cycling, which includes only concentric contractions, during running up inclines eccentric muscle actions play an important role. With steeper inclines, more concentric contractions must be produced to overcome the external force, whereas the amount of eccentric muscle actions decreases. This change in the relative contribution of concentric and eccentric muscle actions, in combination with the fact that eccentric muscle actions require much less metabolic energy than concentric contractions, can explain the difference between the running and cycling delta efficiency.

Adult↗
PubMed2002

Consequence of feedback-based learning of an effective hand rim wheelchair force production on mechanical efficiency.

OBJECTIVE: Investigation of the effect of visual feedback on effective hand rim wheelchair force production and the subsequent effect on gross mechanical efficiency. DESIGN: Ten subjects in an experimental group and 10 subjects in a control group practised three weeks (3.wk(-1), i.e., a pre-test and 8 trials) on a computer-controlled wheelchair ergometer. Every trial consisted of two blocks of 4 min at 0.15 and 0.25 W.kg(-1) at 1.11 m.s(-1). On three trials an additional block at 0.40 W.kg(-1) was performed. The experimental group practised with and the control group practised without visual feedback on the effectiveness of force production. BACKGROUND: In mechanical terms, the low gross mechanical efficiency of hand rim wheelchair propulsion may be the result of ineffective force production. METHODS: During all trials oxygen uptake, power output, forces and torque on the hand rims were measured. RESULTS: In comparison with the control group, the experimental group at trial 8 had a significantly more effective force production compared to the control group (90-97% vs. 79-83%, respectively), but showed a significantly lower mechanical efficiency (5.5-8.5% vs. 5.9-9.9%, respectively). CONCLUSION: Findings indicate that the most effective force production from a mechanical point of view is not necessarily the most efficient way--in terms of energy cost-- from a biological point of view and that force direction is based on an optimization of cost and effect. RELEVANCE: Learning a more effective force production by visual feedback is not useful for increasing the mechanical efficiency of hand rim wheelchair propulsion.

Adult↗
PubMed2001

Expression of hypoxia-inducible factor 1alpha by macrophages in the rheumatoid synovium: implications for targeting of therapeutic genes to the inflamed joint.

OBJECTIVE: To determine if the rheumatoid synovium is a suitable target for hypoxia-regulated gene therapy. METHODS: Sequential sections of wax-embedded synovial membrane samples were obtained from 10 patients with rheumatoid arthritis (RA), 10 with primary osteoarthritis (OA), and from 6 healthy controls. Membrane sections from each patient were immunostained for hypoxia-inducible factor 1alpha (HIF-1alpha) and CD68 (a pan-macrophage marker). RESULTS: HIF-1alpha was expressed abundantly by macrophages in most rheumatoid synovia, predominantly close to the intimal layer but also in the subintimal zone. There was markedly lower expression of HIF-1alpha in OA synovia, and it was absent from all of the healthy synovia. CONCLUSION: These observations indicate that macrophages transduced with a therapeutic gene under the control of a hypoxia-inducible promoter could be administered to RA patients systemically. Migration of these cells to synovial tissue would result in the transgene being switched on in diseased joints but not in healthy tissues.

Adult↗
PubMed2001

Matrix turnover in human cartilage repair tissue in autologous chondrocyte implantation.

OBJECTIVE: Autologous chondrocyte implantation (ACI) is a form of tissue engineering that is being used increasingly to treat damaged articular cartilage. What happens at the graft site subsequent to the transplantation of chondrocytes beneath a periosteal flap has largely remained a matter of conjecture. We examined biopsy samples from the graft site using a panel of specific antibodies to investigate the cellular mechanisms involved and to determine whether remodeling of the matrix occurs. METHODS: Ten full-depth core biopsy samples were obtained from patients who had undergone ACI 9-30 months previously (ages 28-53 years), in addition to 6 "control" biopsy samples. Cryosections were evaluated by standard histologic examination using polarized light and immunohistochemistry. Antibodies specific for type II collagen (CIIC1) were used, as well as antibodies against the C-propeptide of type II collagen (R160) and its denaturation product (Col2-3/4m), as indicators of anabolism or catabolism. In addition, antibodies to the matrix proteinase-generated neoepitopes of the aggrecan core protein were used to demonstrate either aggrecanase (BC-3 and BC-13) or matrix metalloproteinase (MMP) (BC-4 and BC-14) activity. RESULTS: All biopsy samples stained for type II collagen, even in areas of fibrocartilaginous morphology. There was evidence of newly synthesized type II collagen in addition to denatured collagen. MMP and aggrecanase activity on the proteoglycan population was evident, with aggrecanase being more active in fibrocartilaginous areas. CONCLUSION: The findings of this study indicate that ACI is capable of not only cartilage repair but, in some cases, regeneration. This may be achieved by the turnover and remodeling of an initial fibrocartilaginous matrix via enzymatic degradation and synthesis of newly formed type II collagen.

Adolescent↗
PubMed2001

Type II collagen degradation in articular cartilage fibrillation after anterior cruciate ligament transection in rats.

OBJECTIVE: To investigate the kinetics of early cartilage changes in mechanically induced osteoarthritis (OA) and the association of these changes with damage to the type II collagen network. METHODS: Experimental OA was induced by anterior cruciate ligament transsection in the rat knee joint (ACLT-OA). Animals were sacrificed after 2, 7, 14, 28 and 70 days. Knee joints were evaluated using routine histology and immunohistochemistry for denatured (unwound) type II collagen to detect collagen damage. An antibody recognizing the collagenase cleavage site in type II collagen was used to study the role of collagenase in this process. RESULTS: The first changes of the articular cartilage after anterior cruciate ligament transection occurred in the superficial zone. These changes included loss of superficial chondrocytes, swelling of the remaining chondrocytes and superficial fibrillation. The swelling of the chondrocytes did not result from a change towards the hypertrophic phenotype, since these cells did not stain for type X collagen. A marked increase in denatured type II collagen staining was present in the fibrillated areas. Staining of the collagenase cleavage site showed the same distribution as denatured collagen but was clearly less intense. Collagen damage could never be detected before fibrillation occurred and was not present in non-fibrillated areas. CONCLUSIONS: These results indicate that in this model cartilage degeneration starts at the articular surface and that this degeneration is associated with a localized expression of type II collagen degradation products.

Animals↗
PubMed2001

Delta efficiencies of running and cycling.

PURPOSE: The purpose of the present study was to compare delta efficiencies of running with cycling, while several factors that can possibly influence delta efficiency were excluded. METHODS: Twelve subjects performed a submaximal running and cycling test on subsequent days. Delta efficiencies of running and cycling were compared at equal metabolic intensities. Furthermore, rest periods were included in the protocol to avoid fatigue. Pedaling and stride frequencies were held constant during the tests. Finally, the influence of two ways of applying extra external load (inclination of treadmill and horizontal impeding forces) on the delta efficiency of running and cycling was investigated. RESULTS: The results of the present study show that the mean delta efficiency of running (45.5%) is still significantly higher than the mean delta efficiency of cycling (25.7%). The way extra external load is applied does not influence delta efficiency. CONCLUSION: The way of loading and the difference in metabolic intensity can be excluded as causes for the observed difference in delta efficiency between running and cycling. It is suggested that a different contribution in the metabolic load attributable to muscular activity of the arms and/or trunk that does not directly contribute to the work needed to overcome the amount of applied external load may be a relevant factor.

Adult↗
PubMed2000

Differences in type II collagen degradation between peripheral and central cartilage of rat stifle joints after cranial cruciate ligament transection.

OBJECTIVE: Type II collagen degradation is thought to be the key process in cartilage degradation during the development of osteoarthritis (OA). In this study, we investigated the kinetics of type II collagen degradation during surgically induced OA. METHODS: Experimental OA was induced in male Wistar rats by transecting the cranial (anterior) cruciate ligament (CCL). Hematoxylin and eosin staining was used to study overall cartilage degradation, while immunostained sections were used to demonstrate denatured type II collagen (Col2-3/4m antibody) and the collagenase cleavage site in type II collagen (Col2-3/ 4Cshort antibody). RESULTS: During the first 3-4 weeks, cartilage destruction, associated with chondrocyte death, proteoglycan depletion, and a marked increase in the collagenase cleavage neoepitope, was mainly located at the margins of the cartilage. From weeks 3-4, the central part of the cartilage showed increased surface fibrillation and apparent chondrocyte death. In these areas, increased denatured type II collagen staining but little cleavage-site staining was present. CONCLUSION: These results indicate that cartilage degradation after CCL transection in the rat consists of 2 phases. An early phase located at the cartilage margins and a late phase located at the central part of the cartilage. In the early phase, collagenase-dependent cartilage damage occurred. During the late phase, the level of type II collagen denaturation increased.

Animals↗