Biomedical subjects

C Chen

Publications and source records attributed to C Chen.

At least 703 records · Page 39Linked to original sources

PubMed1997

Defining extracellular integrin alpha-chain sites that affect cell adhesion and adhesion strengthening without altering soluble ligand binding.

It was previously shown that mutations of integrin alpha4 chain sites, within putative EF-hand-type divalent cation-binding domains, each caused a marked reduction in alpha4beta1-dependent cell adhesion. Some reports have suggested that alpha-chain "EF-hand" sites may interact directly with ligands. However, we show here that mutations of three different alpha4 "EF-hand" sites each had no effect on binding of soluble monovalent or bivalent vascular cell adhesion molecule 1 whether measured indirectly or directly. Furthermore, these mutations had minimal effect on alpha4beta1-dependent cell tethering to vascular cell adhesion molecule 1 under shear. However, EF-hand mutants did show severe impairments in cellular resistance to detachment under shear flow. Thus, mutation of integrin alpha4 "EF-hand-like" sites may impair 1) static cell adhesion and 2) adhesion strengthening under shear flow by a mechanism that does not involve alterations of initial ligand binding.

Amino Acid Sequence↗

PubMed1997

Effects of aging and food restriction on alpha 1-adrenergic receptors and G-protein in the rat parotid gland.

The aim of this study is to investigate age-related changes in alpha 1-adrenergic receptor and G-protein in rat parotid gland, and to examine whether the age-related changes are modulated by food restriction. The binding characteristics of alpha 1-adrenergic receptor were measured in parotid cell membranes from 3-, 6-, 12-, 18-, and 24-month-old ad libitum-fed (AL) and food-restricted (FR) rats. The number of alpha 1-adrenergic receptors (Bmax) increased between 3 and 6 months by 24.5% and 16.2% in AL and FR rats, respectively, with no further significant change up to 24 months of age. The Kd values of [3H]prazosin binding increased by 53.6% in AL rats, but decreased by 16.1% in FR rats between 3 and 6 months, and the changes were maintained up to 24 months of age. The binding activity of G-protein with [35S]guanosine 5'-[gamma-Thio]triphosphate (GTP[gamma S]) in parotid cell membranes was measured in 6- and 24-month-old AL and FR rats. Basal GTP binding capacity decreased by 22.3% and 26.0% in AL and FR rats, respectively, between 6 and 24 months. Epinephrine-stimulated increase in GTP binding capacity decreased by 19.2% between 6 and 24 months in AL rats, but not in FR rats. The Kd values of [35S]GTP[gamma S] binding were not affected by aging or food restriction. In summary: (1) FR decreased maturation-related increase in the number of alpha 1-adrenergic receptors and prevented maturation-related decrease in receptor binding affinity between 3 and 6 months of age. However, between 6 and 24 months of age FR had no further significant effect on the number of alpha 1-adrenergic receptors and on receptor binding affinity. (2) FR prevented age-related decrease in alpha 1-adrenergic agonist-stimulated increase in GTP binding capacity. We conclude that FR may have a modulatory effect on age-related impairment in alpha 1-adrenergic receptor function resulting from altered G-protein binding activity in the rat parotid gland.

Aging↗

PubMed1997

Dioctyl sodium sulphosuccinate increases net ultrafiltration in peritoneal dialysis.

BACKGROUND: The surface-active substance dioctyl sodium sulphosuccinate (DSS) has been reported to increase the peritoneal clearances of urea and creatinine. This study investigated the effects of DSS on the fluid and solute transport characteristics of the peritoneum. DESIGN: A 4-h single-dwell experiment session of peritoneal dialysis using 25 ml of 3.86% glucose dialysis solution with an intraperitoneal volume maker was performed in 16 male Sprague-Dawley rats. In eight rats, 0.005% (50 p.p.m.) DSS was added to the dialysis fluid. No DSS was given to the other eight rats (control group). The transport of fluid, glucose, potassium, sodium, urea, phosphate and urate were analysed. RESULTS: There was a significant increase in the intraperitoneal volume in the DSS group. At 240 min, the drain volume in DSS group (33.0 +/- 2.9 ml) was significantly higher compared to the control group (28.8 +/- 2.1 ml, P < 0.01). This increase in the drain volume was mainly due to a decrease in peritoneal fluid absorption rate in the DSS group (0.040 +/- 0.013 ml/min) as compared to the control group (0.054 +/- 0.010 ml/min, P < 0.05). There was no significant difference in the diffusive permeability and sieving coefficient for the small solutes between these two groups. However, the clearances for urea and sodium were higher in the DSS group, mainly due to the increase in the dialysate volume. CONCLUSION: Our results suggest that DSS significantly increases the net ultrafiltration of peritoneal dialysis. This effect, which was mainly due to a decrease in the fluid absorption rate, contributed to the increased clearances for urea and sodium. DSS did not alter the diffusive permeability and sieving coefficient for the small solutes.

Animals↗

PubMed1997

Effect of cutting the plantar fascia on mechanical properties of the foot.

A biomechanical model was used to calculate the loadbearing characteristics of the plantar fascia and to determine the effect of cutting the plantar fascia on the stiffness of the foot. With a load of 683 N applied to the foot, the model predicted a 17% increase in vertical displacement and a 15% increase in horizontal elongation when the plantar fascia was cut, compared with the corresponding value when the plantar fascia was intact. Plantar fasciotomy, although clinically satisfactory in cases of recalcitrant heel pain, decreases the stiffness of the foot and creates a less rigid and more deformable arch. The biomechanical model described can help to evaluate the possible outcome of such a procedure.

Elasticity↗

PubMed1997

Childhood hearing impairment: processing dependencies in multidimensional speech perception for an auditory level of analysis.

OBJECTIVE: Our purpose was to determine whether the influence of childhood hearing impairment (HI) on multidimensional speech processing is a purely linguistic effect or whether childhood HI also affects the processing of speech dimensions representing an auditory level of analysis. DESIGN: The processing dependencies characterizing the two dimensions of talker-gender and spatial location were studied in 40 children with HI and in two normal-hearing (NH) comparison groups representing similar chronological ages (N = 30) or similar vocabulary skills (N = 70). The processing interactions were assessed with a speeded selective-attention task requiring listeners to attend selectively to the gender of the talker and to ignore the spatial location and vice versa. The logic is that performance for the target dimension will not be affected by what is happening on the nontarget dimension if the dimensions are processed independently. On the other hand, if the dimensions are not processed independently, listeners will not be able to attend selectively and performance for the relevant dimension will be affected by what is happening on the irrelevant dimension. In the latter case, results may be analyzed in terms of Garner interference (the effect on performance of irrelevant variability in the to-be-ignored dimension) (Garner, 1974a) and Simon interference (the effect on performance of an irrelevant spatial source) (Simon, 1990). RESULTS: Overall results in all listeners, those with NH or HI, showed significant interference when the participants were attending to the gender of the talker and ignoring spatial location and vice versa. The talker-gender and spatial-location dimensions of speech were not processed independently by these children. When the processing interactions were compared between the NH and HI groups, the presence of childhood HI as a general rule significantly diminished the degree of interference from spatial location. The degree of interference from the gender of the talker, on the other hand, remained normal in the presence of childhood HI. All listeners seemed stimulus bound by the gender of the talker. The degree of Garner interference did not show age-related or degree of loss-related change. The degree of Simon interference showed significant change as a function of age in the children with mild-moderate HI, but not in the children with severe HI. The developmental function for Simon interference in the children with mild-moderate HI was delayed to a degree that corresponded to the duration of the auditory deprivation. CONCLUSIONS: The overall pattern of results indicates that the influence of childhood HI on multidimensional speech processing is not a purely linguistic effect.

Age Factors↗

PubMed1997

Absence of Porphyromonas asaccharolytica, Bacteroides fragilis and Chlamydia pneumoniae in human subgingival plaque.

Little is known about the presence of common medical pathogens in the human oral cavity. Using a 16S rRNA-based PCR identification method, this study determined the occurrence of Porphyromonas asaccharolytica, Bacteroides fragilis and Chlamydia pneumoniae in subgingival plaque from 50 adults with advanced periodontitis. Each patient contributed samples from 3 deep periodontal pockets collected by paper points. The PCR primers were for P. asaccharolytica 5'-CTC TAG CTA GAG TGT ACT GG-3' and 5'-ATA GGG TTT ATA GAT TAG CTC TCT-3', for B. fragilis 5'-AAT GAT TCC GCA TGG TTT CAT TA-3' and 5'-GCG GTG ATT GCT CAC TGA CA-3', and for C. pneumoniae 5'- TGA CAA CTG TAG AAA TAC AGC-3' and 5'-CGC CTC TCT CCT ATA AAT-3'. The primers yielded a single amplicon with the respective reference strains and produced no amplicon with colonies of 25 groups of oral organisms. None of the three test species were detected in any of the 50 pooled subgingival samples tested. P. asaccharyolytica, B. fragilis and C. pneumoniae do not seem to be part of the periodontopathic microbiota in humans.

Adult↗

PubMed1997

G(o)2 and Gi3 proteins mediate the action of somatostatin on membrane Ca2+ and K+ currents in ovine pituitary somatotrophs.

1. Growth hormone (GH) secretion from the anterior pituitary gland is mainly regulated by hypothalamic GH-releasing hormone (GHRH) and somatostatin (SRIF). Somatostatin reduces both spontaneous and GHRH-stimulated GH secretion. 2. Exocytosis of GH is mainly determined by the intracellular free Ca2+ concentration ([Ca2+]i), which is regulated by the influx of Ca2+ via membrane Ca2+ channels. Somatostatin reduces the influx of Ca2+ through two separate mechanisms, namely a direct action on Ca2+ channels and an indirect action on membrane potentials through the activation of K+ channels. 3. In the present experiments, somatotroph-enriched cells were obtained from the ovine pituitary gland by means of collagenase dissociation and Percoll-gradient centrifugation. Further identification was based on the effect of SRIF (10 nmol/L) on Ca2+ or K+ currents. 4. A significant reduction in Ca2+ currents and an increase in K+ currents was obtained in response to local application of SRIF (10 nmol/L), but vehicle application had no effect. The responses of Ca2+ and K+ currents to SRIF were reversible after removal of SRIF. 5. Dialysis of GTP-gamma-s (200 mumol/L) abolished the recovery phase of K+ current response to SRIF after its removal, whereas GDP-beta-s (200 mumol/L) totally blocked the response. Pretreatment of the cells with pertussis toxin (100 nmol/L) overnight abolished the Ca2+ current response to SRIF. 6. Intracellular dialysis of antibodies to alpha o, alpha i1-3, alpha i1-2 and alpha i3 subunits of the G-proteins into cells via whole-cell patch-clamp pipettes was confirmed by immunofluorescent staining of the antibodies. 7. Dialysis of anti-alpha i1-3 or anti-alpha i3 antibodies significantly attenuated the increase in the K+ current in response to 10 nmol/L SRIF, whereas neither anti-alpha o nor anti-alpha i1-2 antibodies diminished the effect of SRIF on the K+ current. 8. Dialysis of anti-alpha o antibodies significantly attenuated the reduction in the Ca2+ current that was obtained upon application of 10 nmol/L SRIF. Neither anti-alpha i1-2 nor anti-alpha i3 antibody dialysis diminished the effect of SRIF on the Ca2+ current. 9. Dialysis of the alpha o common antisense oligonucleotides (ASm) but not the alpha i3 AS significantly diminished the inhibitory effect of SRIF on the Ca2+ current. This effect of alpha o ASm dialysis occurred at 12 h incubation after dialysis, reaching a maximal level at 48 h and partially recovering at 72 h incubation. Antisense oligonucleotides specific for alpha o1 (alpha o1 AS) or alpha o2 (alpha o2 AS) were dialysed into somatotrophs and only alpha o2 AS significantly attenuated the inhibition of SRIF on the Ca2+ current. 10. It is concluded that the Gi3 protein mediates the effect of SRIF on the K+ current and that the G(o)2 protein mediates the effect of SRIF on the Ca2+ current in primary cultured ovine somatotrophs.

Animals↗

PubMed1997

Comparison of charcoal- and starch-based media for testing susceptibilities of Legionella species to macrolides, azalides, and fluoroquinolones.

We compared growth characteristics of 46 Legionella strains grown on buffered charcoal yeast extract alpha (BCYE alpha) agar and buffered starch yeast extract (BSYE) agar and MICs of macrolides, azalides, and fluoroquinolones for these organisms. Growth was poor and not reproducible on BSYE agar. Growth was excellent on BCYE alpha, and MICs were easy to interpret. BCYE alpha is superior to BSYE for testing susceptibilities of Legionella species by agar dilution.

Anti-Bacterial Agents↗

PubMed1997

Magnesium-induced conformational change of packaging RNA for procapsid recognition and binding during phage phi29 DNA encapsidation.

Bacteriophage phi29 is typical of double-stranded DNA viruses in that its genome is packaged into a preformed procapsid during maturation. An intriguing feature of phi29 assembly is that a virus-encoded RNA (pRNA) is required for the packaging of its genomic DNA. Psoralen cross-linking, primer extension, and T1 RNase partial digestion revealed that pRNA had at least two conformations; one was able to bind procapsids, and the other was not. In the presence of Mg2+, one stretch of pRNA, consisting of bases 31 to 35, was confirmed to be proximal to base 69, as revealed by its efficient cross-linking by psoralen. Two cross-linking sites in the helical region were identified. Mg2+ induced a conformational change of pRNA that exposes the portal protein binding site by promoting the refolding of two strands of the procapsid binding region, resulting in the formation of pRNA-procapsid complexes. The procapsid binding region in this binding-competent conformation could not be cross-linked with psoralen. When the two strands of the procapsid binding region were fastened by cross-linking, pRNA could neither bind procapsids nor package phi29 DNA. A pRNA conformational change was also discernible by comparison of migration rates in native EDTA and Mg2+ polyacrylamide gel electrophoresis and was revealed by T1 RNase probing. The Mg2+ concentration required for the detection of a change in pRNA cross-linking patterns was 1 mM, which was the same as that required for pRNA-procapsid complex formation and DNA packaging and was also close to that in normal host cells.

Bacillus Phages↗

PubMed1997

Sequential action of six virus-encoded DNA-packaging RNAs during phage phi29 genomic DNA translocation.

A 120-base pRNA encoded by bacteriophage b29 has a novel and essential role in genomic DNA packaging. Six DNA-packaging RNAs (pRNAs) were bound to the sixfold symmetrical portal vertex of procapsids during the DNA translocation process and left the procapsid after the DNA-packaging reaction was completed, suggesting that the pRNA participated in the translocation of genomic DNA into procapsids. To further investigate the mechanism of DNA packaging, it is crucial to determine whether these six pRNA molecules work as an integrated entity or each pRNA acts as a functional individual. If pRNAs work individually, then do they work in sequence with communication or in random order without interaction? Results from compensation and complementation analysis did not support the integrated model. Computation of the probability of combination between wild-type and mutant pRNAs and experimental data of competitive inhibition excluded the random model while favoring the proposal that the six pRNAs functioned sequentially. Sequential action of the pRNA also explains why the pRNA is so sensitive to mutation, since the effect of a pRNA mutation will be amplified by 6 orders of magnitude after six consecutive steps, resulting in the observed complete loss of DNA-packaging activity caused by small alterations. When any one of the six pRNAs was replaced with an inactive one, complete blockage of DNA packaging resulted, strongly supporting the speculation that individual pRNAs, presumably together with other components such as the packaging ATPase gp16, take turns mediating successive steps of packaging. Although the data provided here could not exclude the integrated model completely, there is no evidence so far to argue against the model of sequential action.

Bacillus Phages↗

PubMed1997

Molecular genetic analysis of synaptic plasticity, activity-dependent neural development, learning, and memory in the mammalian brain.

Recently, dozens of mutant mice generated with gene targeting or transgenic technologies have been shown to exhibit a distinct set of impairments in the brain and behavior. In this review, we discuss how studies of mutant mice have helped elucidate the mechanisms that underlie synaptic plasticity and the relationship of these synaptic mechanisms to the activity-dependent phase of neural development and learning and memory. We focus on the recent progress in the analysis of whisker-related pattern formation, elimination of climbing fibers, long-term potentiation, long-term depression, and various learning and memory tasks in mutant mice.

Animals↗

PubMed1997

Can one acquire periodontal bacteria and periodontitis from a family member?

Recent findings suggest that two major periodontal pathogenes, Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis, are transmitted among family members. The authors discuss the evidence of person-to-person transmission of periodontal bacteria, the significance of saliva as a vehicle of transmission and the methods of verifying clonal similarity of bacterial strains obtained from family members. The authors also discuss the prophylactic and therapeutic implications of the person-to-person spread of periodontal bacteria.

Adult↗

PubMed1997

The role of protein kinase C in GH secretion induced by GH-releasing factor and GH-releasing peptides in cultured ovine somatotrophs.

The involvement of protein kinase C (PKC) in the action of GH-releasing factor (GRF) and synthetic GH-releasing peptides (GHRP-2 and GHRP-6) was investigated in ovine somatotrophs in primary culture. In partially purified sheep somatotrophs, GRF and GHRP-2 caused translocation of PKC activity from the cytosol to the cell membranes and caused GH release in a dose- and time-dependent manner. GHRP-6 did not cause PKC translocation. The PKC inhibitors, calphostin C, staurosporine and chelerythrine, partially reduced GH release in response to GRF and GHRP-2 at doses which selectively inhibit PKC activity. These inhibitors totally abolished GH release caused by phorbol 12-myristate 13-acetate (PMA). Down-regulation of PKC by the treatment of cells with phorbol 12,13-dibutyrate for 16 h caused a significant (P < 0.001) reduction in total PKC activity and totally abolished PKC translocation in response to a challenge with GRF, GHRP-2 or PMA. In addition, down-regulation abolished GH release in response to GRF, GHRP-2 or GHRP-6. Treatment of cells with H89, a selective PKA inhibitor, totally blocked GH release caused by either GRF or GHRP-2 and partially reduced PMA-induced GH release. H89 had no effect on PKC translocation caused by GRF, GHRP-2 or PMA and did not affect GH release caused by GHRP-6. These data suggest that GHRP-2 and GRF activate PKC in addition to stimulating adenylyl cyclase activity. Although the cAMP-protein kinase A (PKA) pathway is the major signalling pathway employed by GRF and GHRP-2, the activation of PKC may potentiate signalling via the cAMP-PKA pathway in ovine GH secretion. Importantly, the effect of PMA in increasing the secretion of GH from ovine somatotrophs is effected, in part, by up-regulation of the cAMP-PKA pathway. We conclude that there is cross-talk between the PKC pathway and the cAMP-PKA pathway in ovine somatotrophs during the action of GRF or GHRP.

Alkaloids↗

PubMed1997

Hyaluronan decreases peritoneal fluid absorption in peritoneal dialysis.

Hyaluronan, exhibiting a high resistance against water flow, acts in the tissue as a barrier against rapid changes in water content. To test whether hyaluronan has any effect on the peritoneal fluid and solute transport, and, in particular, on the peritoneal fluid absorption, a 4-h dwell study with an intraperitoneal volume marker (radiolabeled human serum albumin [RISA]) was conducted in 21 male Sprague Dawley rats (three groups, seven rats in each group). Each rat was injected intraperitoneally with 25 ml of 1.36% glucose solution alone (control group), with 0.005% hyaluronan (HA1 group), or with 0.01% hyaluronan (HA2 group). Dialysate and blood samples were taken frequently for analyses of fluid and solute (urea, glucose, and protein) transport. The intraperitoneal volume was calculated from the dilution of RISA with a correction for RISA disappearance from the peritoneal cavity. This study shows that adding hyaluronan to peritoneal dialysis solution significantly (P < 0.01) increased the net peritoneal fluid removal, mainly due to a significant decrease in the peritoneal fluid absorption rate (P < 0.01). The diffusive mass transfer coefficients for glucose, urea, and protein did not differ between the three groups. The peritoneal clearance of urea increased significantly in the two hyaluronan groups compared with the control group, due to the increased net fluid removal in the hyaluronan groups. These results suggest that intraperitoneal administration of hyaluronan during a single peritoneal dialysis exchange may significantly increase the peritoneal fluid and solute removal by decreasing peritoneal fluid absorption.

Absorption↗

PubMed1997

Oral food consumption and subgingival microorganisms: subgingival microbiota of gastrostomy tube-fed children and healthy controls.

This study examined the effect of oral food consumption on the prevalence and levels of subgingival bacteria and yeasts in 20 gastrostomy tube-fed children and 24 healthy controls. Microbial identification was carried out using anaerobic culture and 16S rRNA-based PCR identification methods. Streptococcal and Actinomyces species were recovered from 100% and 76% of all subjects and averaged 66% and 11% of total cultivable organisms, respectively. In decreasing order of prevalence, Fusobacterium, enteric rods, Prevotella intermedia/Prevotella nigrescens, Capnocytophaga, Propionibacterium, yeasts, Actinobacillus actinomycetemcomitans, coagulase-negative Staphylococcus, Campylobacter rectus, Bacteroides forsythus, and Porphyromonas gingivalis were detected in 48% to 2% of the study subjects. The cultivable levels of these species varied widely among subjects. PCR detection showed C. rectus and Eikenella corrodens both to occur in 93% of the study subjects and to be the most prevalent putative periodontal pathogens examined. In decreasing order of prevalence, PCR identified Treponema denticola, A. actinomycetemcomitans, P. nigrescens, P. intermedia, B. forsythus, and P. gingivalis in 38% to 21% of the subjects studied. Tube-fed children and healthy controls exhibited similar subgingival microbial compositions. It appears from this study that oral food consumption is not a major determinant for the establishment of subgingival microbiota in children.

Actinomyces↗

PubMed1997

Determination of human NAT2 acetylator genotype by oligonucleotide ligation assay.

The oligonucleotide ligation assay (OLA) was adapted to the genotyping of the N-arylamine-acetyltransferase (NAT2) gene. This assay allows the use of 96-well microplates and robotic workstations for high sample throughput. We found this assay to be accurate, efficient and reliable. Another advantage for epidemiological studies where the DNA supply is limited is the small amount of genomic DNA required. A single PCR with an input of 50-100 ng of genomic DNA provides sufficient amounts of amplified NAT2 fragment to analyze five missense mutations.

Alleles↗

PubMed1997

Correlation of high-resolution CT and pulmonary function in bronchiolitis obliterans: a study based on 24 patients associated with consumption of Sauropus androgynus.

OBJECTIVE: An outbreak of Sauropus androgynus-associated bronchiolitis obliterans occurred in Taiwan in the summer of 1995. We undertook a study of the correlation between high-resolution CT findings and pulmonary function testing in patients from this outbreak. MATERIALS AND METHODS: We evaluated inspiratory-expiratory high-resolution CT scans of 24 patients with S. androgynus-associated bronchiolitis obliterans. The presence of bronchiectasis was assessed by two visual scores (a bronchial dilatation score and a bronchiectasis extent score). Extent of air-trapping was assessed visually and given a score. We also used computer software to assess the extent of air-trapping and generate scores of dynamic attenuation. Spirometry, plethysmography, and diffusion capacity of each patient were also obtained. RESULTS: All four scores had statistically significant correlation with forced expiratory volume in 1 sec (FEV1) (p < .05 for both bronchiectasis scores; p < .001 for both air-trapping scores). The two air-trapping scores had statistically significant correlation with forced vital capacity and diffusion capacity. We found the scores for dynamic attenuation had the greatest correlation with FEV1 (r = .85). We also found that mosaic attenuation was notable on expiratory CT scans alone in nine patients (type 1 air-trapping) and on both inspiratory and expiratory CT scans in 15 patients (type 2 air-trapping). In the latter group, FEV1 was significantly lower (p < .01). CONCLUSION: Findings from high-resolution CT of air-trapping were more important than findings of bronchiectasis when correlating pulmonary function with S. androgynus-associated bronchiolitis obliterans. Type 2 air-trapping suggested a more severe air-flow obstruction than did type 1. Scores for quantitative attenuation generated by computer software were helpful in assessing air-trapping and correlating it with pulmonary function. These findings may apply to patients with bronchiolitis obliterans from other causes.

Adult↗

PubMed1997

Thigh muscle size and strength after anterior cruciate ligament reconstruction and rehabilitation.

It is the hypothesis of the senior author (GAA) that high circumference measurements are not an accurate reflection of thigh muscle cross-sectional area or muscle strength after standard rehabilitation following anterior cruciate ligament reconstruction. Likewise, normal quadriceps femoris strength is not achieved in these patients despite aggressive rehabilitation. The purpose of our study was to quantify thigh muscle size and strength and correlate thigh circumference, muscle cross-sectional area by magnetic resonance imaging (MRI), and isokinetic strength in our patients. Thirty-three patients with anterior cruciate ligament repair utilizing autografts of iliotibial band (N = 28), semitendinosus autograft (N = 3), and bone-patellar tendon-bone autograft (N = 2) were retrospectively evaluated 48.7 +/- 6.91 months after surgery. We compared involved operated extremities with uninjured, uninvolved contralateral extremities, measuring thigh circumference, isokinetic peak torque, and cross-sectional area by MRI. We found a significant 1.8% decrease in thigh circumference, a 10% decrease in average quadriceps torque, and a 8.6% decrease in quadriceps cross-sectional area by MRI in the involved extremities compared with the uninvolved extremities. A positive correlation between MRI cross-sectional area, quadriceps, and hamstring peak torque was recorded in involved and uninvolved extremities. A positive correlation between thigh circumference, quadriceps, and hamstring peak torque was found in uninvolved extremities but not in operated extremities. The authors concluded that thigh circumference underestimates atrophy and is not correlated with cross-sectional thigh muscle area by MRI or strength in operated extremities. Persistent quadriceps weakness and decreased cross-sectional area at 49 months postsurgery and rehabilitation continue to challenge our efforts. The pathophysiology of the decrease in thigh muscle size and quadriceps femoris strength is discussed.

Adolescent↗