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Biomedical subjects

B Roger

Publications and source records attributed to B Roger.

At least 19 recordsLinked to original sources
PubMed2003

Hip-spine relationship: a radio-anatomical study for optimization in acetabular cup positioning.

The criteria for acetabular cup positioning during total hip replacement are a matter of considerable discussion, particularly with regards to the optimal degree of anteversion. "Anatomical anteversion" is defined in the transverse plane, and "surgical anteversion" in the sagittal plane. Computed tomography measurements of anteversion are characteristic of a given transverse section plane and fail to take into account the position of the pelvis. We suggest a simple method for evaluating acetabular cup position in both the transverse and sagittal planes during standing and sitting. By shedding new light on the relationships between the pelvis and the spine, this method may help to understand some cases of impingement, instability or abnormal wear.

Acetabulum↗
PubMed2001

Patellar tendon-lateral femoral condyle friction syndrome: MR imaging in 42 patients.

OBJECTIVE: To demonstrate the MR imaging findings that occur between the posterior inferolateral patellar tendon and the lateral femoral condyle in patients with chronic anterior and or lateral knee pain. PATIENTS AND DESIGN: A retrospective review of the MR images in 42 patients who presented with chronic anterior or lateral knee pain was performed by two musculoskeletal radiologists. In 15 patients, post-contrast images were available. RESULTS: Sagittal and axial imaging planes best demonstrated the patellar tendon and its relationship with the lateral femoral condyle. In 40 patients, there was obliteration of the fat planes and abnormal signal intensity in the lateral soft tissues of the inferior patellofemoral joint. Enhancement after administration of gadolinium was noted in all cases in which contrast was administered. Eighteen patients showed cystic changes in the soft tissues adjacent to the lateral femoral condyle in addition to fat plane obliteration. In two patients, only cystic changes were noted in the lateral soft tissues. Abnormal patellar alignment was noted in 37 patients. Patellar tendon pathology was seen in nine patients. CONCLUSION: In evaluating anterior knee symptoms, MR imaging allows identification of changes that may be related to patellar tendon-lateral femoral condyle friction syndrome and that should be distinguished from other causes of anterior or lateral knee pain.

Adolescent↗
PubMed2000

Interaction of nucleolin with an evolutionarily conserved pre-ribosomal RNA sequence is required for the assembly of the primary processing complex.

The first processing event of the precursor ribosomal RNA (pre-rRNA) takes place within the 5' external transcribed spacer. This primary processing requires conserved cis-acting RNA sequence downstream from the cleavage site and several nucleic acids (small nucleolar RNAs) and proteins trans-acting factors including nucleolin, a major nucleolar protein. The specific interaction of nucleolin with the pre-rRNA is required for processing in vitro. Xenopus laevis and hamster nucleolin interact with the same pre-rRNA site and stimulate the processing activity of a mouse cell extract. A highly conserved 11-nucleotide sequence located 5-6 nucleotides after the processing site is required for the interaction of nucleolin and processing. In vitro selection experiments with nucleolin have identified an RNA sequence that contains the UCGA motif present in the 11-nucleotide conserved sequence. The interaction of nucleolin with pre-rRNA is required for the formation of an active processing complex. Our findings demonstrate that nucleolin is a key factor for the assembly and maturation of pre-ribosomal ribonucleoparticles.

Animals↗
PubMed2000

MR arthrography of the hip: normal intra-articular structures and common disorders.

This pictorial review illustrates the anatomical features of normal intra-articular components of the hip and their common disorders on MR arthrography. On T1-weighted MR arthrograms, the normal contrast-filled joint cavity shows a homogeneous high signal intensity. Normal acetabular labrum appears as a well-delineated triangle showing a low signal intensity, surrounded by contrast material in the perilabral recess. Intra-articular paramagnetic contrast outlines labral tears, loose bodies, communicating labral cysts and cartilage lesions (traumatic tears, focal defects, degenerative fissures and thinning), and improves their detection. Overall, MR arthrography enables accurate detection and staging of hip intra-articular structure abnormalities.

Hip Joint↗
PubMed2000

Sagittal alignment in lumbosacral fusion: relations between radiological parameters and pain.

The objective of this study was to conduct a radiological analysis of posture before and after lumbosacral fusion to evaluate the influence of spinal alignment on the occurrence and pattern of post surgical pain. The study included 81 patients, of whom 51 had a history of previous low back surgery. We excluded patients with suspected or confirmed nonunion. In the fusion group, the 27 patients who were pain free after the procedure were compared to the 54 patients with residual pain. Thirty patients had pain only or primarily when they were standing immobile, 18 when they were sitting immobile, and six in both positions. Measurements were done on full-length lateral radiographs of the spine, with the patient standing according to Duval Beaupère criteria. The subgroup with postfusion pain was characterized at baseline by a more vertical sacrum with less sacral tilt (ST) (P < 0.0062) and more pelvic tilt (PT) (P < 0.0160). PT at last follow-up (PT fu) correlated with the presence of postfusion pain (NP: P = 0.0003). In the patients with postfusion pain, PT was almost twice the normal value. ST at last follow-up (ST fu) in the standing position was also correlated with the presence of postfusion pain (P < 0.0001) indicating that the sacrum remained abnormally vertical in the subjects with postfusion pain. Using logistic regression, the only prognostic factor for residual pain at last follow-up was ST fu. Both at pre-operative evaluation and at last follow-up, patients with pain in the standing position or in both the standing and sitting positions were characterized at pre-operative status by a more vertical sacrum with less sacral tilt. The results of this study indicate that, achieving a strong fusion should not be the only goal. Appropriate position of the fused vertebrae is also of paramount importance to minimize muscle work during posture maintenance. The main risk is failing to correct or to causing excessive pelvic retroversion with a vertical sacrum leading to a sagittal alignment that replicates the sitting position. This situation is often accompanied by loss of lumbar lordosis and adversely affects stiff or degenerative hips.

Adult↗
PubMed2000

Plantar fasciitis and fascial rupture: MR imaging findings in 26 patients supplemented with anatomic data in cadavers.

Understanding of the normal anatomy of the plantar aponeurosis (PA) and familiarity with pathologic conditions are required for an accurate evaluation of the patient with subcalcaneal heel pain. In this study, we evaluated the diagnostic capabilities of magnetic resonance (MR) imaging in the assessment of the PA with close anatomic correlation. Herein, we describe the MR imaging features of plantar fasciitis and fascial rupture in 26 patients. High-spatial-resolution MR imaging was performed in four cadaveric feet, and a prescribed imaging plane was used for depiction of the peroneal component of the PA. MR imaging delineated the anatomy of the PA and perifascial soft tissues. The peroneal component was best visualized in prescribed sagittal oblique images. Perifascial edema was the most common finding of plantar fasciitis, and it was remarkable in those cases with acute fascial rupture. MR imaging reliably delineated the anatomy of the PA and may allow precise localization and definition of the extent of involvement in disease processes.

Adolescent↗
PubMed2000

Anticoagulant activity and pharmacokinetic properties of a sub-cutaneously administered mixed micellar formulation of argatroban in experimental animals.

We have studied the anticoagulant properties of a novel mixed micellar formulation containing 14 mg/ml argatroban administered by the sub-cutaneous (s.c.) route to rats, rabbits, dogs and primates. Blood samples were taken at various times post-treatment for the determination of the thrombin time (TT), Ecarin clotting time (ECT) and the activated partial thromboplastin time (aPTT). Plasma levels of argatroban were determined in the dog and primate. Mixed micelles alone (0.15 M sodium glycocholate and 0.15 M egg lecithin) were without effect on the clotting parameters. The mixed micellar formulation of argatroban dose-dependently increased all three clotting parameters in the rat (1-4 mg/kg), the rabbit (1 and 2 mg/kg), the dog (1 and 2 mg/kg) and the primate (0.25 and 0.5 mg/kg). In each case the TT was the most sensitive parameter, followed by the ECT and the aPTT. The duration of action of argatroban in each species was dose dependent and varied from 3 h in the rat to 6 h in the dog. In the latter, the mixed micelle formulation had a significantly increased plasma half-life and mean residence time without affecting the overall area under the curve. The increases in the clotting time were strongly correlated with the plasma levels of argatroban and were linear across the range of concentrations obtained in the dog and the primate, although the aPTT plasma concentration response curve was very flat. Species differences were noted between the increase in clotting time for a given plasma concentration, with the primate being more sensitive than the dog (e.g. 4.7 times more so in terms of the ECT). Thus, a mixed micellar formulation of argatroban, which markedly enhances its solubility, could be useful as a potential anticoagulant for sub-cutaneous administration.

Animals↗
PubMed1999

Structure and functions of nucleolin.

Nucleolin is an abundant protein of the nucleolus. Nucleolar proteins structurally related to nucleolin are found in organisms ranging from yeast to plants and mammals. The association of several structural domains in nucleolin allows the interaction of nucleolin with different proteins and RNA sequences. Nucleolin has been implicated in chromatin structure, rDNA transcription, rRNA maturation, ribosome assembly and nucleo-cytoplasmic transport. Studies of nucleolin over the last 25 years have revealed a fascinating role for nucleolin in ribosome biogenesis. The involvement of nucleolin at multiple steps of this biosynthetic pathway suggests that it could play a key role in this highly integrated process.

Animals↗
PubMed1999

Imaging findings in the dominant shoulder of throwing athletes: comparison of radiography, arthrography, CT arthrography, and MR arthrography with arthroscopic correlation.

OBJECTIVE: Conventional radiography, arthrography, CT arthrography, and MR arthrography--including use of the abduction and external rotation position--were compared, with arthroscopic correlation, to determine the spectrum of abnormalities encountered and the relative benefits of each imaging method in the evaluation of shoulder lesions occurring in 17 throwing athletes. SUBJECTS AND METHODS: Each of 36 athletes with shoulder pain aggravated by abduction and external rotation was examined in a single visit during which conventional radiography, arthrography, CT arthrography, and MR arthrography were performed. In 17 of these athletes, imaging findings were compared with those at arthroscopy. All images were independently evaluated by two groups of musculoskeletal radiologists. RESULTS: Structures found to be affected were, in decreasing order of frequency, the following: the posterosuperior labrum, supraspinatus tendon, infraspinatus tendon, humeral head, glenoid cavity and rim, acromioclavicular joint, anteroinferior capsulolabral complex, biceps tendon, and subscapularis tendon. MR arthrography without and with abduction and external rotation yielded the highest sensitivity and specificity for all lesions with the exceptions of bone sclerosis and enthesophytes (which were best seen with CT arthrography). MR arthrography with abduction and external rotation was most accurate for diagnosis of rotator cuff and anteroinferior capsulolabral complex tears. CONCLUSION: On the basis of these preliminary results, we believe that MR arthrography with abduction and external rotation should be part of the imaging evaluation of shoulder pain in throwing athletes, owing to the high sensitivity of this imaging technique.

Adult↗
PubMed1999

Pericruciate meniscal cysts arising from tears of the posterior horn of the medial meniscus: MR imaging features that simulate posterior cruciate ganglion cysts.

OBJECTIVE: The purpose of this study is to describe MR imaging features of an unusual type of meniscal cyst arising from tears of the posterior horn of the medial meniscus in 10 patients. MATERIALS AND METHODS: Retrospective review of MR examinations of the knee was performed of 10 patients (nine men, one woman; mean age, 39 years) in whom evidence of a meniscal tear and a cyst-like structure around the posterior cruciate ligament (PCL) was seen. RESULTS: An oval mass with low signal intensity on T1-weighted MR images and increased signal intensity on T2-weighted MR images posterior to the PCL, simulating a PCL ganglion cyst, was seen in all 10 patients. A tear of the posterior horn of the medial meniscus was also seen in all patients. The sites of communication between the cyst and meniscal tear were observed in sagittal MR images in eight patients. Septation within the cyst and associated joint effusion were seen in eight and four patients, respectively. Arthroscopy in eight patients and transmeniscal needle drainage in the other two patients confirmed both the meniscal tear and the pericruciate meniscal cyst. CONCLUSION: Pericruciate meniscal cysts cause fluid collections posterior to the PCL, simulating a PCL ganglion cyst. Careful analysis of the posterior horn of the medial meniscus should be performed when a cyst-like structure is seen adjacent to the PCL.

Adolescent↗
PubMed1999

[Mobility of a polyethylene tibial insert in a mobile total knee prosthesis].

PURPOSE: We have studied the mobility of a mobile tibial implant in total knee arthroplasty (TKA) by a radiographical evaluation. MATERIAL AND METHODS: We analyzed mobility of the polyethylene tibial insert of 15 "G2S" TKA implanted for one year or more. We established a dynamic radiographical evaluation. We used 3 weight-bearing radiographs: AP in extension and two lateral (one in extension and one at 90 degrees of flexion), two AP with femoral internal and external rotation, 2 strict lateral X-rays in neutral rotation in antero-posterior replacement with a 25 kilograms strength Telos, and 2 AP in varus and valgus with Telos. Wilcoxon's test and Fisher's exact test were used for statistical evaluation. RESULTS: Our study demonstrated preservation of the polyethylene mobility in tibial TKA implant in all movements: in rotation, in antero-posterior translation with Telos, and even in antero-posterior translation during physiological condition with flexion-extension weight-bearing radiographs. Statistical tests were very significant. We noticed that flexion induced anterior translation of tibial polyethylene when PCL was preserved. CONCLUSION: This study answered to our question whether mobility of TKA tibial implant persists after implantation. This mobility should reduce loosening forces to the tibia and stress in the polyethylene component. Now we have to determine the amplitude of mobility required to reach this objective.

Arthroplasty, Replacement, Knee↗
PubMed1997

MRI of plantar fasciitis.

At present, MRI is the only imaging method that can precisely visualize lesions of the superficial plantar aponeurosis, whether they be musculoaponeurositides, enthesopathies or tears, and whether they be acute or chronic, with or without complications. By its direct visualization of the lesion, MRI enables an accurate assessment of the injury to be made and thereby better orients the therapeutic strategy.

Fascia↗
PubMed1997

Combined effects of caloric restriction and branched-chain amino acid supplementation on body composition and exercise performance in elite wrestlers.

Twenty-five competitive wrestlers restricted their caloric intake (28 kcal.kg-1.day-1) for 19 days, using a hypocaloric control (hC, n = 6), hypocaloric high-protein (hHP, n = 7), hypocaloric high-branched-chain amino acid (hBCAA, n = 6), hypocaloric low-protein (hLP, n = 6) diet to determine the effects of caloric restriction on body composition and performances versus control diet (C, n = 6). Anthropometric parameters (weight, percent body fat) and adipose tissue (AT) distribution measured by magnetic resonance imaging (MRI) obtained before and after diet, were compared. A significant highest body weight loss (-4 kg, p < 0.05) and decrease in the percent of body fat (-17.3%, p < 0.05) were observed for subjects of the hBCAA group. Subjects of the hBCAA group exhibited a significant reduction (-34.4%, p < 0.05) in abdominal visceral adipose tissue (VAT). There was no change in aerobic (VO2max) (p > 0.75) and anaerobic capacities (Wingate test) (p > 0.81), and in muscular strength (p > 0.82). We conclude that under our experimental conditions, the combination of moderate energy restriction and BCAA supplementation induced significant and preferential losses of VAT, and allowed maintainance of a high level of performance.

Amino Acids, Branched-Chain↗
PubMed1997

[Cystic compression of the suprascapular nerve. Value of imaging. Apropos of 6 cases and review of the literature].

Six cases of suprascapular nerve entrapment by a ganglion cyst within the spinoglenoid notch or developed from the glenoid labrum are reported. Causes of injury or entrapment of the suprascapular nerve are described including traction or kinking of the nerve, trauma, repetitive exercise, or compression by ganglion cyst. The patients had non specific pain, weakness, and atrophy of the spinatus musculature. Electromyography showed evidence of denervation atrophy. Patients had plain radiographs, arthrography, CT-arthrography, magnetic resonance imaging (MRI) and MR-arthrography. Masses that caused suprascapular nerve entrapment were well localized and characterized wit magnetic resonance imaging, reflecting the superior soft-tissue contrast of this modality. In addition, MRI may demonstrate atrophy of the spinatus muscles. MR-arthrography allows to visualize lesions of the glenoid labrum and in some cases, demonstrates cysts filling.

Adult↗