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V A Pedrini

Publications and source records attributed to V A Pedrini.

11 recordsLinked to original sources
PubMed1995

Morphological and biochemical effects of strenuous exercise on immature long bones.

To determine the effects of intense exercise on the growth of long bones in immature animals, young male white leghorn chickens were run five days per week starting at four weeks of age on motor-driven treadmills. Work intensity was determined on the basis of maximal oxygen consumption (VO2 max) with the exercise intensity maintained at 70-80 percent VO2 max. Young animals ran continuously for 30 minutes, older animals 45 to 60 minutes each day. Runners and controls (10 animals per group) were sacrificed at 8, 12, 14 and 20 weeks of age. The lengths of the femurs and tibiotarsus were significantly stunted at 8-, 12- and 14 weeks in the runners but had nearly recovered at 20 weeks of age. Both bones also demonstrated significantly decreased total cross-sectional areas in 8-, 12- and 14 week-old runners as well as decreased cortical cross-sectional areas. The tibiotarsus also remained significantly smaller in the 20-week-old runners, but the femur had recovered in terms of radial growth. Intermolecular pyridinoline collagen crosslinks were identical in amount in the two groups with the femur collagen significantly less cross-linked than the tibiotarsus. The delayed growth of the exercised avian young bone is consistent with data obtained from children and young mammalian models. The osteogenic response to exercise that produces an increased bone mass in adult tissue appears either suppressed or overcome in young avian bone indicating that it may be erroneous to assume that data obtained from adult tissue are also applicable to young growing bone.

Animals↗
PubMed1992

Effects of microgravity on the composition of the intervertebral disk.

The lumbar annuli of rats flown on COSMOS 2044 were compared with those of three control groups and a tail-suspension experimental model. The wet and dry weights of the annuli were significantly smaller (P less than 0.05) in the flight group than in three control groups. The collagen-to-proteoglycan ratio was significantly greater (P less than 0.001) in the flight group than in the three control groups, but there were no detectable changes in the relative proportions of type I and II collagen or in the number of pyridinoline cross-links. When the annuli were immersed in water for 2 h, more proteoglycans (P less than 0.001) leached from the annuli of flown rats than from the tissue of control animals, suggesting abnormal or smaller proteoglycans. Safranin-O indicated a normal spatial distribution of the proteoglycans within the annulus. Tail suspension did not affect the size of the annuli, but more proteoglycans (P less than 0.05) leached from the tissue of suspended animals than from the normal annuli. The reasons for smaller disks and the abnormal ratio between the fibrous collagenous network and the proteoglycan gel in the flight group are unknown at this time. It is, however, probable that these changes may affect the biomechanical functions of the annulus, although they may be temporary and totally reversible if injuries are avoided in the interim period.

Animals↗
PubMed1988

Response of immature chicken meniscus to strenuous exercise: biochemical studies of proteoglycan and collagen.

Male white Leghorn chickens were exercised on a treadmill at 70-80% of their maximal oxygen consumption starting at 4 weeks and continuing up to 20 weeks of age. The effect of the strenuous exercise regime on the extracellular matrix of menisci was followed through studies of proteoglycans and collagen. Avian menisci contain type I collagen, chondroitin sulfate proteoglycans, which increase with age in amount and degree of aggregation, and dermatan sulfate proteoglycans, which decrease with age. Five weeks of exercise cause a premature decrease of dermatan sulfate proteoglycans, while the chondroitin sulfate-containing molecules become significantly more aggregated than those of the tissue of age-matched controls. Strenuous exercise also causes a significant decrease in the number of pyridinoline crosslinks per mole of collagen in the menisci of young runners. The exercise-induced changes of proteoglycan and collagen occur only during the period of active growth, and all parameters return to normal when the animals reach skeletal maturity. The early proteoglycan aggregation and dermatan sulfate decrease induced by exercise are probably an adaptation to the increased loading. Although the mechanism by which strenuous exercise reduces or delays the formation of collagen pyridinoline crosslinks in menisci of skeletally immature animals is unknown, their decrease could negatively affect the mechanical properties of the tissue during the period of active growth.

Adaptation, Physiological↗
PubMed1986

Structural and mechanical adaptation of immature bone to strenuous exercise.

To investigate the adaptive responses of immature bone to increased loads, young (3-wk-old) White Leghorn roosters were subjected to moderately intense treadmill running for 5 or 9 wk. The training program induced significant increases in maximal O2 consumption and muscle fumarase activity in the 12-wk-old birds, demonstrating that growing chickens have the ability to enhance their aerobic capacity. The structural and mechanical properties of the runners' tarsometatarsus bones were compared with sedentary age-matched controls at 8 and 12 wk of age. Suppression of circumferential growth occurred with exercise at both ages, whereas exercise enhanced middiaphysial cortical thickening, especially on the bones' concave surfaces. Although cross-sectional area moments of inertia did not change with exercise, significant decreases in bending stiffness, energy to yield, and energy to fracture were observed. It was concluded that strenuous exercise may retard long-bone maturation, resulting in more compliant bones.

Adaptation, Physiological↗
PubMed1985

Morphological and biochemical effects of sodium morrhuate on tendons.

The purpose of this study was to determine some of the morphological and biochemical effects of sodium morrhuate injections into intact rabbit patellar tendons and Achilles tendons. The effects of one, three, and five 100 microliters injections of sodium morrhuate on tendon circumference, cell content, collagen fibril diameter, collagen-proteoglycan relationships, water content, amino sugar content, and hydroxyproline content were investigated over periods of 1, 4, and 9 weeks. In general, sodium morrhuate injected tendons were larger in diameter and contained more cells, smaller collagen fibrils, increased water and amino sugar content, and reduced hydroxyproline content compared with their contralateral controls. As a sclerosing agent, sodium morrhuate appears to mimic the early stages of an injury-repair sequence when injected directly into intact tendons. Whether sodium morrhuate may hasten repair responses or improve joint laxity remains to be determined.

Achilles Tendon↗
PubMed1985

Patellar tendon matrix changes associated with aging and voluntary exercise.

Male rats maintained under constant environmental conditions were randomly assigned to nonrunner (NR) and voluntary exercise (R) groups. At 9 mo, voluntary exercise significantly increased muscle cytochrome c concentration and citrate synthase activity. Also, at the same age, R animals had significantly greater glycosaminoglycan concentration than NR, but no changes in dry weight and collagen concentration were significant. By age 28 mo, the R groups had reduced daily running by 70%, and elevation of tendon glycosaminoglycans relative to NR animals was no longer statistically significant. A similar trend was noted for muscle mitochondrial markers. Aging significantly decreased tendon glycosaminoglycans and increased collagen concentration. Although aging reduced the total amount of voluntary exercise, the concentration of tendon glycosaminoglycans in 28-mo-old runners was equivalent to levels in 9-mo-old sedentary rats, suggesting that voluntary exercise slowed the decline in galactosamine-containing glycosaminoglycans with aging.

Aging↗
PubMed1984

Pseudoachondroplasia: biochemical and histochemical studies of cartilage.

Cartilage from patients with pseudoachondroplasia is characterized by unique inclusions in the cisternae of the endoplasmic reticulum and proteoglycan abnormalities have been suggested in this form of dwarfism. To elucidate the nature of the proteoglycan defect, we determined the amount of the individual glycosaminoglycans present in iliac-crest cartilage of three patients and extracted the proteoglycan monomers from one of the samples. Sections of iliac-crest cartilage and proximal fibular growth plates were examined by electron microscopy and also stained with hematoxylin and eosin, safranin O-fast green, and alcian blue in the presence of increasing concentrations of magnesium chloride (zero to one molar). The chondrocytes of the iliac crest and fibular physes were arranged in clusters more than in columns and contained characteristic endoplasmic reticulum inclusions, which were particularly large in the hypertrophic cells. The cartilage stained very poorly with hematoxylin and eosin and with safranin O-fast green. The alcian-blue stain was abolished from perilacunar areas and from longitudinal septa by magnesium chloride concentrations that were lower than those required by normal tissue. The proteoglycans of iliac-crest cartilage were found to be significantly enriched in keratan sulphate and had a below-normal ratio of chondroitin-4-sulphate to chondroitin-6-sulphate, although the amount of the two isomeric chondroitin sulphates combined was within normal limits. The urinary excretion of glycosaminoglycan by the three patients was normal. Pseudoachondroplasia appears to be a generalized cartilage disorder involving abnormalities of proteoglycans, probably related to the core protein or to enzymes that are responsible for the formation of the glycosaminoglycan chains.(ABSTRACT TRUNCATED AT 250 WORDS)

Achondroplasia↗
PubMed1983

Histochemical properties of cartilage proteoglycans.

Proteoglycan interaction with alcian blue at different concentrations of magnesium chloride was studied both in vitro and in histological sections of paraffin-embedded tissues. Our experiments indicate that a) proteoglycans with different contents of chondroitin sulfate and keratan sulfate, prepared under nondegradative conditions, are not distinguishable on the basis of the critical electrolyte concentrations at which staining is abolished; b) the state of aggregation of proteoglycans only very slightly affects the alcian blue affinity of the macromolecules at different concentrations of magnesium chloride; c) the interaction of proteoglycans with other components of the connective tissue matrix is an important factor in determining the strength of binding of alcian blue to the polyanionic macromolecules in histological sections. These factors should be considered in interpreting histochemical data obtained by staining tissue sections with alcian blue at different concentrations of magnesium chloride. Proteoglycans, like glycosaminoglycans, are only weakly periodic acid-Schiff-positive.

Achondroplasia↗