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Biomedical subjects

A Verdonck

Publications and source records attributed to A Verdonck.

32 records · Page 2Linked to original sources
PubMed1998

Effect of testosterone replacement after neonatal castration on craniofacial growth in rats.

Neonatal castration precludes the pubertal increase in serum testosterone and reduces general and craniofacial growth in the male Wistar rat. This study aimed to determine whether exogenous testosterone given at an age beyond the normal pubertal peak restores general and craniofacial growth in male, neonatally castrated rats. The design was a randomized, double-controlled, cross-sectional trial. Male Wistar rats were assigned by weighted randomization to be either castrated early after birth (n = 35) or not (n = 15). On day 57, a 1.5-cm Silastic tube with testosterone was implanted in 18 of the castrated rats. On day 70 and day 110, body length, weight, and craniofacial growth were measured together with the weight of the prostate, and blood samples taken. The exogenous testosterone resulted in a significant increase in serum testosterone and prostate weight. All measures of general and craniofacial growth had higher mean values in the non-castrated control group than in the castrated group, while in the testosterone-implant group the mean values lay between these of the castrated animals and the non-castrated controls. Two-way ANOVA indicated a significant effect of the testosterone administration on lower-incisor growth and the size of the total skull vault.

Analysis of Variance↗
PubMed1998

Comparative effects of neonatal and prepubertal castration on craniofacial growth in rats.

The role of endogenous testosterone in the craniofacial growth of the young male rat was investigated. First, the effect of neonatal surgical castration was examined in a randomized, cross-sectional study in which male Wistar rats were allocated to be either castrated or sham-operated 4 h after birth. Then, the effect of prepubertal chemical castration was analysed in a second, randomized longitudinal study in which male Wistar rats were randomly allocated either to a control group or to two experimental groups, one injected with triptorelin at day 25 and the other injected on day 25 and on day 45. Every tenth day between 20 and 70 days of age for the first study, and between 30 and 110 days of age for the second, body length and weight were measured, cephalometric X-rays taken, and blood samples obtained. Neonatal and prepubertal castration resulted in decreased plasma concentrations of testosterone and in delayed growth of somatic and craniofacial components. The initiation, duration and magnitude of the effect was dependent on individual bones (cranial base, skull roof) and on the lower incisor, and related to the testosterone concentrations. These results suggest that testosterone effects participate in the process of normal craniofacial growth, particularly during puberty.

Aging↗
PubMed1997

Pain and other cardinal TMJ dysfunction symptoms: a longitudinal survey of Japanese female adolescents.

Longitudinal data were obtained for 4 years from 361 Japanese high school girls between the ages of 12 and 16. The data were analysed for the occurrence of pain and its associations with the occurrence of other cardinal TMJ dysfunction symptoms and occlusal states. It was determined that even if pain or noise or jaw-deviation symptoms appeared, those symptoms did not necessarily last thereafter. The symptoms were not persistent but rather appeared and disappeared repetitively. Those who exhibited noise during at least one of the surveys of the 4-year survey period showed a significantly higher prevalence of pain than those who did not exhibit noise at all (P < 0.05). Those who exhibited noise by the age of 13 showed a significantly higher prevalence of pain than those who exhibited noise after age 14 (P < 0.1). The temporal occurrence of pain depended upon the appearance of noise and the age at which noise first appeared. On the other hand, the occurrence of pain symptoms was not necessarily related to specific types of malocclusions, which suggests the significance of multifactorial contributions in understanding the aetiology of pain rather than the occlusal factor.

Adolescent↗
PubMed1994

Contraction patterns during isokinetic eccentric and concentric contractions after anterior cruciate ligament injury.

Muscular fatigue was investigated in m. rectus femoris, m. vastus lateralis and medialis of 15 patients after an anterior cruciate ligament injury. Using a Lido active (isokinetic) dynamometer, combined eccentric and concentric contractions were carried out at intermediate contractile velocity speeds (150 degrees, 240 degrees/s). In addition, concentric contractions were also performed at fast angular velocities (300 degrees, 400 degrees/s). The results indicated that fatigue was significantly greater for the intermediate speeds. Given one angular velocity, the average eccentric force decline was more pronounced than the concentric one. At all velocities the relative decrease of peak torque (PT) was smaller than for contractional work (CW).

Adult↗
PubMed1994

The prevalence of cardinal TMJ dysfunction symptoms and its relationship to occlusal factors in Japanese female adolescents.

Cross-sectional data were obtained from 1182 Japanese high school girls of 12 and 15 years old. The data were analysed for the prevalence of specific occlusal features and the prevalence of cardinal Temporomandibular Joint Dysfunction (TMJD) symptoms in different occlusion groups. The associations between occlusal features and TMJD symptoms were analysed by the Z-analysis. The results were as follows: the prevalence of TMJD symptoms (total) was about 23% in both age groups examined. Noise had the highest prevalence of the specific TMJD symptoms in both age groups (16% and 11%). With age and for different occlusion groups, there was a significant increase in deviation on opening (P < 0.001) and a decrease in pain and noise (P < 0.05). No significant associations were found between the occurrence of TMJD symptoms (total) and occlusal features in all the examined occlusion groups. With respect to specific TMJD symptoms, however, the investigation of the different groups revealed a significant association (P < 0.05) of intra-arch occlusal (crowding) features with the occurrence of deviation on opening and with the occurrence of the combined TMJD symptoms which include deviation on opening. This indicates that crowding may be an important sign for predisposing TMJD. For the other single disorder symptoms (except pain), we did not find a significant relationship (P < 0.05) with aspects of occlusion, which may confirm a multifactorial TMJD problem wherein occlusal features can have a contribution to TMJD.

Adolescent↗
PubMed1994

[Relationship between endocrinology and craniofacial growth. I: Puberty and craniofacial growth. II: Growth of the craniofacial skeleton].

In this literature, a review is given of the endocrinology and morphology of the craniofacial complex. This article reviews in a first part the endocrinology of puberty and general growth aspects. Afterwards the adolescence growth spurt of the face and the hormonal regulation will be focused. In a second part the morphogenetic aspects together with growth area's and growth theories of the craniofacial complex will be discussed. At last a detailed description of the maxillary and mandibular growth is given.

Adolescent↗
PubMed1993

The interaction between soft tissues and the sagittal development of the dentition and the face.

The purpose of this study was to investigate whether there are relationships between the cross-sectional surface area (CSSA) of the lips and the sagittal structure of the skeletal parts of the face and the dentition in the midsagittal plane and whether the sagittal structure of the face and the dentition is related to the class of malocclusion. The CSSA of the upper and lower lip was measured with a planimeter on the lateral cephalograms of 156 patients before their orthodontic treatment with a closed lip relation in rest. They were divided into 18 groups according to their age, sex, and Angle classification. The Quick Ceph program (Orthodontic Processing, Chula Vista, Calif.) was used to digitize and analyze 23 dental and skeletal parameters. The parameters were tested by an analysis variance to show differences between the three classes of malocclusion. The regression analysis was used to look for relations between the CSSA and the skeletal or dental parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Mucormycosis during deferoxamine therapy is a siderophore-mediated infection. In vitro and in vivo animal studies.

This study investigates the pathophysiology of mucormycosis caused by Rhizopus, which has been reported in 46 dialysis patients, while treated with deferoxamine (DFO). This drug aggravates mucormycosis, which we experimentally induced in guinea pigs and which lead to a shortened animal survival (P < or = 0.01). The drug's effect on Rhizopus is not mediated through the polymorphonuclear cells. Fe.DFO, the iron chelate of DFO, abolishes the fungistatic effect of serum on Rhizopus and increases the in vitro growth of the fungus (P < or = 0.0001). This effect is present at Fe.DFO concentrations > or = 0.01 microM, at which fungal uptake of radioiron from 55Fe.DFO is observed. A 1,000-fold higher concentration of iron citrate is required to achieve a similar rate of radioiron uptake and of in vitro growth stimulation as observed with Fe.DFO. These in vitro effects of Fe.DFO (1 microM) in serum on radioiron uptake and on growth stimulation are more striking for Rhizopus than for Aspergillus fumigatus and are practically absent for Candida albicans. For these three fungal species, the rates of radioiron uptake from 55Fe.DFO and of growth stimulation in the presence of Fe.DFO in serum are directly related (r = 0.886). These results underscore the major role of Fe.DFO in the pathogenesis of DFO-related mucormycosis. Pharmacokinetic changes in uremia lead to a prolonged accumulation of Fe.DFO after DFO administration, which helps explain the increased sensitivity of dialysis patients to DFO-related mucormycosis.

Animals↗
PubMed1991

[Lack of fatigue of the musculature in patients after immobilization--a paradox?].

The isometric strength of knee extensors was measured in patients six weeks after cruciate ligament surgery over a contraction period of 30 sec. The characteristics of the graph obtained form the measurement system were compared to the graphs of uninjured knee extensor muscles. Apart from strength reductions, as expected for atrophic muscle, the pattern of the strength graph led to the impression that these muscles did not fatigue during prolonged contraction. This paradoxical phenomenon can be explained by the existence of central inhibitory mechanisms.

Anterior Cruciate Ligament↗
PubMed1987

Influence of acylcarnitines of different chain length on pure and mixed phospholipid vesicles and on sarcoplasmic reticulum vesicles.

Palmitoyl-, myristoyl- and lauroylcarnitine destabilize small unilamellar vesicles of 1,2-dipalmitoyl-n-glycero-3-phosphorylcholine (DPPC) and 1,2-dimyristoyl-n-glycero-3-phosphorylcholine (DMPC) into multilamellar liposomes. Their effect on the bilayer is dependent on the acyl chain length of the acylcarnitine, the ratio of the lengths of the acyl chains of the phospholipid and the acylcarnitine and the molar ratio of the phospholipid to acylcarnitine but not the absolute concentration of the acylcarnitine in the solute. Sarcoplasmic reticulum vesicles are broken down by each of the acylcarnitines at concentrations below their critical micellar concentrations (CMC). These three acylcarnitines stimulate the Mg2+, Ca2+-ATPase activity in SR-vesicles to a certain maximum, after which a net inhibition is observed. The maximum degree of stimulation depends highly on acyl chain length: the shorter the chain length, the more effective. In the same concentration range where the Mg2+, Ca2+-ATPase activity is increased, the net Ca2+-uptake is markedly decreased.

1,2-Dipalmitoylphosphatidylcholine↗
PubMedDate not supplied

[Muscle stress of rehabilitation-oriented concentric and concentric-eccentric implemented isokinetic training].

The method of lactate diagnostics is used to compare the isokinetic concentric and eccentric work pattern in conjunction with relevant muscular stress. Therefore two training groups performed at isokinetic velocity spectra of 90 degrees/s, 120 degrees/s, 150 degrees/s and 180 degrees/s four series each. The factor "work" was kept identical by performing the same training extent. Over the four series it turned out that the eccentric training group had a continuously higher lactate value of 0.5 mmol/l than the concentric training group used as comparison. The results of both groups gave a similar lactate concentration during practice. Nevertheless it showed that a two minute break is not sufficient to initiate a regeneration process.

Adult↗
PubMedDate not supplied

[Effects of various load intensities in the framework of postoperative stationary endurance training on performance deficit of the quadriceps muscle of the thigh].

The development of a muscular hypertrophy represents one of the most important purpose in a postoperative training. With the example of an isokinetic training the present study was meant to record if the choice of the load intensity is of importance in this connection. 36 patients with an anterior crucial ligament rupture, who were divided into three groups, underwent a stationary training for a period of four weeks. Thereby it could be proved that high intensity mainly influences the intramuscular coordination while the load intensity is far less relevant to the influence on a muscular cross-section. In this connection rather the total extent of practice time makes up the specific stimulus for a hypertrophy.

Adult↗