Comparison of amounts and properties of collagen and proteoglycans in condylar, costal and nasal cartilages

In this study we compared the compositions of extracellular matrices of condylar, costal and nasal cartilages to characterize differences in growth patterns in relation to matrix composition. Condylar, costal and nasal cartilages of 25- and 35-day-old rabbits were extracted and subjected to bio- and histochemical analysis to determine total amounts of collagen and amounts and aggregating properties of proteoglycans. We found that proteoglycan content and aggregate formation were greatest in nasal cartilage, and lower in costal and markedly lower in condylar cartilage. The amount of proteoglycans increased by varying amounts in all samples with age. Collagen content was highest in costal cartilage. In 25-day-old rabbits the quantity of collagen in condylar cartilage exceeded that in nasal cartilage. In 35-day-old rabbits the quantities were nearly the same. It is suggested that collagen does not only provide tensile strength, but counteracts forces responsible for interstitial growth such as osmotic pressure. Based on the results, it seems that the amount of proteoglycans is greater in cartilages, which have greater independent growth potential. Variations in increase in amount of proteoglycans with age could reflect differences in the timing of growth of such cartilages.     

Incidence, nature, and causes of ice hockey injuries. A three-year prospective study of a Swedish elite ice hockey team

In this prospective study, we have investigated incidence of injuries of different severity, types of injury, and mechanisms of injury during ice hockey practice and games. One Swedish elite hockey team was closely observed during three seasons (1982 to 1985). There was a total number of 95 injuries and 29 facial lacerations. The majority of injuries were minor (73%) and only 8% were classified as major. Seventy-six percent of the injuries occurred during games and 24% during practice. The incidence of injury during practice was 1.4 per 1,000 player-practice hours and 78.4 per 1,000 player-game hours. In comparison with other sports, the incidence of injury during hockey practice is very low, while that during games is high. Eighty percent of the injuries were caused by trauma and 20% by overuse. The most common types of injury were contusions, strains, and sprains. Complete tear of the medial collateral ligament of the knee was the most common severe injury. Most injuries resulted from body contact, predominantly tackling (checking), and from puck or stick contact. A reduction of the number of minor and moderate injuries should be possible by stricter enforcement of the hockey rules, especially against stick violations, and more widespread use of visors.     

Effect of hypoxia on the synthesis of glycosaminoglycans and collagen by rabbit aortic smooth muscle cells in culture

This study evaluated the effect of hypoxia on the connective tissue metabolism of rabbit aortic smooth muscle cells (SMCs) in culture. When the oxygen saturation of the incubation medium was lowered from 20% to 2-3%, synthesis of sulphated glycosaminoglycans (GAGs) and hyaluronic acid, as determined from the incorporation of [3H]glucosamine, was stimulated. However, this occurred only after 24 h preincubation of the SMCs in hypoxia. The collagen synthesis of the cells was determined from the incorporation of [3H]proline into protein hydroxyproline and calculated in mass units from the specific intracellular precursor radioactivity. The total protein synthesis was similarly determined from the incorporation of [3H]proline into protein-bound proline. Hypoxia decreased the collagen synthesis, but did not affect the total protein synthesis of the cells. When compared with the control cultures the cell protein of the SMC cultures kept in hypoxia, decreased on the first day in hypoxia whereafter it increased. These results may explain the mechanisms by which hypoxia affects the connective tissue metabolism of the arterial wall in vivo.     

Selection of criteria for assessment of occlusal acceptability

There is no general agreement on criteria that could be applied to distinguish between orthodontically acceptable and non-acceptable occlusions after the completion of dental development. The aim of the present study was to analyse morphological and functional features that could be used as an index to define an acceptable occlusion in young adults. Three expert panels representing specialists in orthodontics and stomatognathic physiology participated in a modified Delphi method. Each panel responded to a questionnaire concerning the usefulness of various occlusal features, and a set of characteristics was selected on the basis of the responses; thereafter, applicability of the chosen characteristics and their cutoffs for an acceptable-non-acceptable dichotomy was tested clinically. To obtain a consensus level of 100%, the last panel session was completed with a group discussion. Assessments made using the morphological criteria were compared with those made with the dental health component of the Index of Orthodontic Treatment Need. The selected morphological characteristics consisted of overjet, overbite, canine relationship, crossbite, scissors bite and midline deviation. The functional evaluation comprised assessments of discrepancy between the centric relation and the intercuspal position, working- and non-working-side contacts and protrusion contacts. The dental health component and our morphological criteria showed different sensitivity to contact point displacements, interdigitation in buccal segments and increased overbite. This study provides a set of morphological and functional indicators reflecting the current consensus opinion of Finnish professionals. Further studies are needed to analyse the reproducibility of assessment of the characteristics included.     

Balance board training: prevention of traumatic injuries of the lower extremities in female soccer players?

This prospective randomized intervention investigated whether training on a balance board could reduce the amount of traumatic injuries of the lower extremities in female soccer players. A total of 221 female soccer players from 13 different teams playing in the second and third Swedish divisions volunteered to participate in the study. Seven teams (n = 121) were randomized to an intervention group and six teams (n = 100) to a control group and were followed during one outdoor season (April-October). Before and after the season muscle flexibility and balance/postural sway of the lower extremities were measured in the players. There were no significant differences in age, height, weight, muscle flexibility and balance/postural sway of the lower extremities between the intervention and the control group. During the season the players in the intervention group performed a special training program consisting of 10-15 min of balance board training in addition to their standard soccer practice and games. After a 37% drop-out the intervention group consisted of 62 players and the control group of 78 players. The results showed no significant differences between the groups with respect either to the number, incidence, or type of traumatic injuries of the lower extremities. The incidence rate of "major" injuries was higher in the intervention group than in the control group. Four of five anterior cruciate ligament injuries occurred in the intervention group, which means that we could not prevent severe knee injuries in female soccer players with balance board training. However, among the players who had been injured during the 3-month period prior to this investigation there were significantly more players from the control group than from the intervention group who sustained new injuries during the study period.     

Demonstration of Cerebral Plasticity by Intra-Operative Neurophysiological Monitoring: Report of an Uncommon Case

Summary  It has been postulated long ago that “eloquent” areas shift their location in patients with arteriovenous malformations (AVM). Obviously the “motor region” in not located in the precentral gyrus in a patient with an AVM in the “motor region”.  We report on the case of a 15-year old boy with an AVM in the left sensorimotor cortex, in whom intra-operative mapping showed an inexcitability of the precentral gyrus, while stimulation of the cortex anterior to the primary motor cortex elicited motor responses. This indicates that motor function was translocated from the primary to the supplementary motor cortex. Surgery was performed under general anaesthesia. Neurophysiological monitoring was performed throughout surgery. The central sulcus was identified by phase reversal of the somatosensory evoked potentials. The motor cortex was mapped by direct high-frequency (500 Hz) monopolar anodal stimulation.  In the patient herein reported, stimulation of the “anatomically” defined primary motor cortex induced no motor response, as expected. Motor response was elicited only by stimulation of the cortex anterior to the precentral gyrus. There was no postoperative deterioration of motor function. These observations indicate that the precentral gyrus was functionally “useless”. The motor region was relocated into more rostral areas in the supplementary motor cortex. This translocation of function in the presence of an AVM indicates cerebral plasticity.     

Placental protein 12 (PP12): factors affecting levels in late pregnancy

The circulating concentration of placental protein 12 was measured by radioimmunoassay in 109 pregnant women. The effect on the serum PP12 level of temperature, repeat freezing and thawing, and day-to-day and diurnal variation were assessed and the post partum changes of levels were studied. On average, PP12 levels in plasma are about one-half of those in serum in the same individual. PP12 immunoreactivity is destroyed by heating but not by repeated freezing and thawing. Changes in serum PP12 levels at various times of day showed a significant and consistent diurnal variation (F = 7.21; d.f.24; 96; P less than 0.001). The peak mean (+/- s.e.m.) value at 0800 h (80.8 +/- 8.7 ng/ml) was 41 per cent higher than the 24-h mean (P less than 0.05), and the nadir concentration at 1400 h (40.4 +/- 5.4 ng/ml) was 29 per cent lower than the 24-h mean (P less than 0.025). There is also considerable day-to-day variation (up to 72 per cent) in serum PP12 levels. If serum samples are taken at 0700 h, there is a slight negative correlation between PP12 concentration and placental weight (P less than 0.05), but not between PP12 level and birthweight of the child. In term pregnancy, the levels taken at 0700 h are higher (163.7 +/- 12.4 ng/ml) than at 0900 to 1300 h (115.7 +/- 11.4 ng/ml, P less than 0.001). The PP12 level is not affected by labour.(ABSTRACT TRUNCATED AT 250 WORDS)     

Anterior cruciate ligament injuries in young females playing soccer at senior levels

The aim of this investigation was to study the consequences of anterior cruciate ligament injuries in female soccer players. Special interest was focused on young female soccer players (< 16 years) sustaining anterior cruciate ligament injuries when playing at a senior level, which means playing together with players 19 years or older. In Sweden, all players belonging to an organized soccer club are insured by the same insurance company, the Folksam Insurance Company. Data of all soccer-related knee injuries in females reported to the Folksam Insurance Company between 1994 and 1998 were collected. A questionnaire was sent to 978 females who were registered to have sustained a knee injury before the age of 20 years. The response rate was 79%. Three hundred and ninety-eight female soccer players who had sustained an anterior cruciate ligament injury before the age of 19 years were analysed. Most of their anterior cruciate ligament injuries had been diagnosed using arthroscopy or magnetic resonance imaging (84%). Thirty-eight percent of the players had been injured before the age of 16 years. Of these, 39% were injured when playing in senior teams. When playing in senior teams 59% of the players below the age of 16 years and 44% of the players 16 years or older sustained their ACL injuries during contact situations. At the time of this investigation (2-7 years after the anterior cruciate ligament injury), altogether 78% (n = 311) reported that they had stopped playing soccer. The most common reason (80%) was symptoms from their anterior cruciate ligament-injured knee. It appears that many young female soccer players injure their anterior cruciate ligament when playing at a senior level. Therefore, we suggest that female soccer players under the age of 16 years should be allowed to participate only in practice sessions but not games at a senior level.