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Biomedical subjects

M Moreau

Publications and source records attributed to M Moreau.

At least 55 records · Page 3Linked to original sources
PubMed2002

Development of the neurocentral junction as seen on magnetic resonance images.

The neurocentral junction (NCJ) is a cartilaginous growth plate in the vertebra that has been implicated as a potential cause of adolescent idiopathic scoliosis (AIS) since the early 1900s. Studies to date have focused on the age of closure without characterizing normal NCJ development. Using MRI, the normal development of the NCJ image can be determined and the stages preceding the disappearance of the NCJ image can be characterized. 405 NCJs from 11 pediatric patients were examined using MRI and the various images were categorized. NCJ development encompassed five stages, with a specific pattern of absence of the NCJ image noted in each vertebra and in the vertebral column as a whole. The image of the NCJ first became absent in the cervical region (age 6), then in the lumbar region (age 12) and finally in the thoracic region (age 14). These patterns of development serve as a baseline to evaluate NCJ pathology in conditions such as adolescent idiopathic scoliosis (AIS).

Adolescent↗
PubMed2002

The components of the magnetic resonance image of the neurocentral junction.

The neurocentral junction (NCJ) is a cartilaginous growth plate located between the vertebral centrurn and the neural arch. In characterizing the age of closure of this growth plate, anatomic studies have suggested that the NCJ closes before age 10, whereas MRI studies have suggested that the NCJ does not fuse until adolescence In this study, gross anatomic and histologic sections were correlated with MR images to determine the components of the NCJ image. The NCJ image appeared as a thick white line that was shown to encompass the cartilage of the growth plate, the surrounding woven bone and a portion of the trabecular bone of the vertebra. Although the MR pixels were too large to completely resolve the tissues that surround the growth plate, MRI was shown to be a valuable technique of visualizing the NCJ cartilage and further MRI studies of the human NCJ are needed.

Age Factors↗
PubMed2002

Spine-Straight device for the treatment of kyphosis.

Kyphosis is an excessive rounding of the upper spine. Its treatment depends upon the severity, the age of the patient and the levels of the spine that are affected. Early diagnosis is a key to providing optimal treatment. In a skeletally immature patient, an exercise program or bracing is the most commonly used treatment. However, the compliance of bracing for adolescents is poor and exercise training is labor intensive. The purpose of this study is to determine whether a Spine-Straight device can help patients to correct their kyphosis themselves and there by reduce back pain without the biomechanical support of a brace. The Spine-Straight device consists of an accelerometer and a microcomputer unit. The accelerometer is used to measure the kyphotic angle and the microcomputer unit controls a pager vibrator to alert patients when their posture exceeds personalized thresholds. The system was tested in the laboratory before used by subjects. The results were compared to back data obtained from a laser scanner imaging system. The maximum angle deviation between the laser scanner and the Spine-Straight device was 1.5 degrees. Two volunteers tested the systems for 2 days. The accelerometer was placed at the T3 location and the microcomputer unit was carried during daily activities. The angle measurement was recorded at 1 minute intervals during daily activity over a period of 2 days. The preliminary trials demonstrate subjects can improve their posture when feedback signals were provided.

Adult↗
PubMed2002

Long-term follow-up of surgically treated AIS patients.

The aim of this study was to determine the long-term changes in spine and trunk alignment in patients who have undergone scoliosis surgery. Twenty-three (16F; 7M; at age of surgery 15.7 +/- 4.9 years) patients with adolescent idiopathic scoliosis agreed to participate and had posterior-anterior radiographs and surface topography prior to derotation surgery, within 6 months of surgery, at 2 years post-operatively and 5-10 years (mean follow-up period 6.11 +/- 1.6 years) after surgery. Cobb angles, surface trunk rotations, and cosmetic scores were measured at each visit. A questionnaire assessed back appearance and pain at the 5-10 year follow-up. The results of the questionnaire were compared to 25 patients with idiopathic scoliosis who had recently undergone surgery. A paired two-tailed Student's t-test with p=0.05 was used to compare the deformity between visits. The Cobb angle and cosmetic score improved after surgery while the change in trunk rotation was insignificant (p=0.37). Between the two-year and 5-10 year review, the Cobb angle, cosmetic score, and surface trunk rotation significantly increased. Self-perception of appearance and pain were similar to the control group. Surgical correction of scoliosis is not completely maintained during adulthood although the radiographic and surface deterioration does not appear to be clinically significant.

Adolescent↗
PubMed2002

Assessing the impact of pelvic obliquity in post-operative neuromuscular scoliosis.

The goal of this pilot study was to explore the relationship between pelvic obliquity and patient pain, sitting tolerance, pressure sores, and function. Five neuromuscular patients who underwent spinal surgery 6-26 weeks prior to assessment took part in this on-going study (4F; 1M); age at surgery (14.6 +/- 2.6 years). Pelvic obliquity was measured from pre- and post-operative anterior-posterior radiographs. A force-sensing pad with a grid of sensors was placed on a flat surface and the weight distribution pattern was recorded. The pressures were divided into left and right sides and peak levels were noted on each side. The parents or caregivers completed a questionnaire on their child's pain, sitting tolerance, pressure sores, and functional abilities. Pelvic obliquity was reduced after surgery by approximately 50% depending on the method used to assess pelvic obliquity. The major curve was reduced from 64 degrees(10 degrees) to 39 degrees (10 degrees). Post operatively, the average pressure (left/right side) ranged from 1.2 to 2.0 (average 1.6). The peak pressure ratio ranged from 1.1 to 1.9 (average 1.4). The ratio of left/right pressure correlated with improvement in pelvic obliquity (r2=0.9). Pain was moderate/severe in the 2 patients with the least correction as measured with the Cobb angle from surgery; both improved following surgery. Two patients suffered pressure sores pre-operatively and one post-operatively. Only 3/5 felt sitting endurance had increased. All parents felt their child sat straighter after surgery. The outcome measures of pain, pressure sores, sitting tolerance, and function were not well related to the amount of pelvic obliquity. More candidates and a longer follow-up may shed light on the many relationships.

Activities of Daily Living↗
PubMed2001

Evaluation of contraceptive efficacy and cycle control of a transdermal contraceptive patch vs an oral contraceptive: a randomized controlled trial.

CONTEXT: Oral contraceptive (OC) pills are effective, but poor compliance increases rates of pregnancy during treatment. OBJECTIVE: To compare the contraceptive efficacy, cycle control, compliance, and safety of a transdermal contraceptive patch and an OC. DESIGN: Randomized, open-label, parallel-group trial conducted October 1997 to June 1999. SETTING: Forty-five clinics in the United States and Canada. PARTICIPANTS: A total of 1417 healthy adult women of child-bearing potential. INTERVENTIONS: Participants were randomly assigned to receive a transdermal contraceptive patch (n = 812) vs an OC (n = 605) for 6 or 13 cycles. Patch treatment consisted of application of 3 consecutive 7-day patches followed by 1 patch-free week. MAIN OUTCOME MEASURES: Overall and method-failure Pearl Indexes (number of pregnancies/100 person-years of use) and life-table estimates of the probability of pregnancy were calculated. Cycle control, compliance, patch adhesion, and adverse events were also assessed. RESULTS: Overall and method-failure Pearl Indexes were numerically lower with the patch (1.24 and 0.99, respectively) vs the OC (2.18 and 1.25, respectively); this difference was not statistically significant (P =.57 and.80, respectively). The incidence of breakthrough bleeding and/or spotting was significantly higher only in the first 2 cycles in the patch group, but the incidence of breakthrough bleeding alone was comparable between treatments in all cycles. The mean proportion of participants' cycles with perfect compliance was 88.2% (811 total participants, 5141 total cycles) with the patch and 77.7% (605 total participants, 4134 total cycles) with the OC (P <.001). Only 1.8% (300/16 673) of patches completely detached. Both treatments were similarly well tolerated; however, application site reactions, breast discomfort, and dysmenorrhea were significantly more common in the patch group. CONCLUSION: The contraceptive patch is comparable to a combination OC in contraceptive efficacy and cycle control. Compliance was better with the weekly contraceptive patch than with the OC.

Administration, Cutaneous↗
PubMed2001

Pineal transplantation after pinealectomy in young chickens has no effect on the development of scoliosis.

STUDY DESIGN: Three experimental groups and one control group of chickens underwent different surgical procedures to determine the effects of pineal gland transplantation on the development of scoliosis. OBJECTIVE: To determine whether transplantation of the pineal gland to the body wall musculature maintains serum melatonin levels at normal values and prevents the development of scoliosis. SUMMARY OF BACKGROUND DATA: Scoliosis occurs consistently after pinealectomy in young chickens. Many characteristics of this scoliosis are similar to those seen in patients with adolescent idiopathic scoliosis. It is not clear whether the underlying mechanism is dependent on reduced levels of serum melatonin or some other aspect of the extensive surgery. METHODS: Four groups of chickens were selected: normal chickens, pinealectomized chickens, chickens that underwent simple cutting of the pineal stalk, and chickens that underwent transplantation of the pineal gland into the body wall. Development of scoliosis was determined from measurement of the Cobb angle from weekly radiographs. RESULTS: All of the experimental groups showed the same levels of incidence and the same patterns of scoliosis development. Serum melatonin levels were reduced to nearly zero in all the experimental groups for the duration of the experiment. Scoliosis developed in none of the normal chickens. CONCLUSIONS: Neither transplantation of the pineal gland into the body wall musculature nor simple cutting of the pineal stalk was able to maintain normal levels of serum melatonin because both procedures reduced levels to nearly zero. The incidence and pattern of scoliosis development in these groups were the same as those for the pinealectomized group. Reduction of serum melatonin levels remains a prerequisite for scoliosis development in young chickens.

Animals↗
PubMed2001

Quantitative determination of C-polysaccharide in Streptococcus pneumoniae capsular polysaccharides by use of high-performance anion-exchange chromatography with pulsed amperometric detection.

Capsular polysaccharides of Streptococcus pneumoniae are used to formulate polyvalent pneumococcal vaccines. A sensitive method, using high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD), has been developed to quantify the contamination of pneumococcal capsular polysaccharides (PnPs) with the C-polysaccharide (C-Ps). As this polysaccharide is highly immunogenic, and since anti C-Ps antibodies are not protective, the need to monitor and reduce its level is of uppermost importance. The method is based on the quantification by HPAEC-PAD of ribitol, which is released by a two-step hydrolysis of the PnPs using aqueous hydrofluoric acid (HF) followed by trifluoroacetic acid hydrolysis (TFA). This simple method has been shown to provide both qualitative and quantitative information about the purity of polysaccharide preparations.

Bacterial Capsules↗
PubMed2001

Development of scoliosis following pinealectomy in young chickens is not the result of an artifact of the surgical procedure.

Pinealectomy in young chickens consistently results in scoliosis, which has many characteristics similar to those seen in adolescent idiopathic scoliosis. The mechanism underlying this phenomenon remains a mystery and it is not yet entirely clear whether some unidentified aspect of the extensive surgery is the major factor rather than the removal of the pineal gland. Four different types of pinealectomy surgery were performed on young chickens as well as deliberate damage to the cerebral cortex which simulated the extreme of any accidental damage that might occur during surgery. Scoliosis was assessed from weekly radiographs. No differences in incidence of scoliosis, degree of severity, or pattern of curve development were observed for any of the experimental groups when compared with controls. In all groups approximately 55% of the chickens developed scoliosis that progressed rapidly. Different pinealectomy procedures and deliberate damage to the cerebral cortex produce scoliosis in young chickens with the same incidence and characteristics. This suggests strongly that the mechanism behind the phenomenon is due to the removal of the pineal gland and not some artifact of the extensive surgery. The pinealectomy model in young chickens is proving to be a good model for studying AIS in humans. An understanding of the mechanism underlying this phenomenon has the potential to provide further insights into the etiology of AIS and can lead to the development of novel treatment methods.

Animals↗
PubMed2001

The critical stage of pinealectomy surgery after which scoliosis is produced in young chickens.

STUDY DESIGN: Stages of the surgical procedure for pinealectomy in chickens were identified. Groups of chickens were selected for each stage. Scoliosis development was identified from radiographs. OBJECTIVES: To determine the critical stage of surgery for pinealectomy after which scoliosis develops in young chickens. SUMMARY OF BACKGROUND DATA: Pinealectomy in young chickens consistently produces scoliosis in young chickens that has many characteristics similar to those seen in patients with adolescent idiopathic scoliosis. The mechanism behind this phenomenon remains unknown. METHODS: Five distinct stages in the pinealectomy surgery were identified. Groups of chickens were selected to undergo surgery to represent these five stages. Scoliosis was determined from weekly radiographs. RESULTS: Cutting the pineal stalk was identified as the critical stage in the surgery after which scoliosis developed. The incidence of scoliosis did not increase after more extensive surgery in which the pineal bulb was removed from the skull. This stage was also correlated with a significant reduction of serum melatonin levels. CONCLUSIONS: Cutting the pineal stalk was identified as the critical stage of pinealectomy surgery after which scoliosis may develop. This stage was also correlated with the significant reduction of average serum melatonin levels. These results allow the focus of attention into the mechanism behind this phenomenon to center on the consequences of cutting the pineal stalk rather than total removal of the pineal gland.

Animals↗
PubMed2001

Weak TCR stimulation induces a calcium signal that triggers IL-4 synthesis, stronger TCR stimulation induces MAP kinases that control IFN-gamma production.

Th1 and Th2 cells produce different cytokines and have distinct functions. Th1/Th2 cell differentiation is influenced, among other factors, by the nature of TCR-MHC interactions. However, how the TCR transduces a signal resulting in IFN-gamma or IL-4 production is a matter of debate. For example, some authors reported a loss of calcium signaling pathway in Th2 cells. We used a T cell hybridoma producing IL-4 upon weak TCR stimulation and both IL-4 and IFN-gamma for strong TCR engagement as a model to study how TCR signaling pathways are differentially activated in both conditions of stimulation and how this influences the production of cytokines. We show that: (1) the calcium response is identical following weak and strong TCR stimulation; (2) mitogen-activated protein kinase(MAPK) activation is a gradual phenomenon depending upon the strength of TCR activation; (3) a calcium response, even weak, triggers IL-4 expression; (4) IFN-gamma synthesis requires not only a calcium response but also MAPK activation. The MAPK pathway is dispensable for IL-4 production, although it amplifies IL-4 synthesis upon strong TCR stimulation; (5) TCR-induced IL-4 production also depends on calcium signaling in Th2 cells, while IFN-gamma synthesis is dependent, in addition, on MAPK activation in Th1 cells.

Animals↗
PubMed2001

Texture analysis of X-ray radiographs is a more reliable descriptor of bone loss than mineral content in a rat model of localized disuse induced by the Clostridium botulinum toxin.

Botulism is a generalized paralyzing disease caused by the toxin of Clostridium botulinum (BTX). The toxin acts 3-4 days after injection by blocking the release of acetylcholine to the muscle. Six Wistar rats received a 2-U injection of BTX in the right quadriceps. Six rats were similarly injected with saline and were used as control. Paralysis of the quadriceps was obtained 4-5 days after the injection. Animals were killed 4 weeks after the BTX injection. The bone mineral content (BMC) was measured by dual-energy X-ray absorptiometry (DXA) on the femur and tibia. No side-to-side difference was observed for BMC on the whole tibia and femur in the BTX group. When subregions were selected in the bones, a significant decrease in BMC was obtained on the proximal tibia (-17.4 +/- 2.5%, p < 0.02). No significant difference could be observed on the proximal or distal femur, nor on the diaphyseal shafts. Numeric X-rays were done and a region of interest was transferred to an image analyzer. The texture of the trabecular bone was analyzed by the run length and fractal methods (skyscrapers and blanket). Significant differences were obtained on the proximal tibia for all methods except with fractal skyscrapers. On the distal femur, significant differences were obtained with the run length method, and the skyscrapers and the blanket method in the vertical direction. No differences were obtained with any method on the tibia and femur from control animals. Bone is a highly anisotropic material and its architecture at the microscopic level is conditioned by strains. The trabecular pattern differs in the proximal tibia than in the distal femural. Depending on the trabecular anisotropy, the algorithms can be more or less pertinent. BTX induced a significant bone loss on the bony subparts that are directly influenced by disuse. Texture analysis of X-ray images can reveal differences that were not evidenced by naked eyes. However, a combination of several methods appears necessary to appreciate the bone loss.

Absorptiometry, Photon↗
PubMed2001

[Calcium and bioluminescent probes].

Ca2+ is an universal second messenger in numerous cell physiological processes. Aequorin, a bioluminescent calcium-binding protein is used today as a cellular probe to measure and image variations in calcium concentrations. The paper describes the characteristics and the use of aequorin as a luminescent calcium probe, and the future in the use of this protein for calcium imaging.

Aequorin↗
PubMed2001

[Calcium-dependent pathways involved in the production of cytokines in lymphocytes].

CD4+ T lymphocytes are divided in Th1 cells producing IFN gamma and Th2 cells that synthetize IL-4. This paper describes signaling pathways activated following T cell receptor (TCR) engagement and emphasizes differences that can account for differential cytokine production. This paper focuses on a new signaling pathway involved in IL-4 synthesis. This pathway couples the TCR to PKC that controls a calcium entry through dihydropyridine sensitive calcium channels. The calcium response is sufficient to initiate IL-4 gene transcription. Differing from that of IL-4, IFN gamma gene expression always requires MAP-kinase activation in addition to a calcium signal.

Calcium↗
PubMed2001

[HIV-1 Tat protein induces IL-10 production by human monocytes: implications of the PKC and calcium pathway].

In asymptomatic patients infected by HIV-1, the level of IL-10, a cytokine with immunosuppressive activity, is associated with the course of HIV infection towards AIDS. We show that HIV-1 Tat, a viral protein secreted by infected cells, induces IL-10 production by human peripheral blood monocytes. The analysis of the signal transduction pathways strongly suggests that the protein kinase C may play an essential role in this induction. Stimulation by Tat induces nuclear translocation of the transcription factor NFkB the activation of which seems to be necessary for IL-10 production. Using microspectrofluorimetry and confocal microscopy, we also show that Tat induces a calcium influx.

Calcium↗
PubMed2001

[Neural determination in Xenopus laevis embryos: control of early neural gene expression by calcium].

In amphibian embryos the central nervous system derives from the dorsal region of the ectoderm. Molecular studies led to the formulation of the "neural default model" in which neural development is under the inhibitory control of members of the BMP family. These growth factors also act as epidermis inducers. The neural fate is revealed by factors secreted by the Spemann Organizer such as noggin, chordin, follistatin, Xnr3 and cerberus which act by blocking BMP signalling. We propose a new model for neural cell determination in which a signalling pathway controlled by an increase in intracellular calcium suppresses the epidermis fate and activates the neural fate instead. This increase in calcium is due to an influx through calcium channels of the L-type, expressed in ectodermal cells during gastrulation. The possible involvement of a calcium-dependent phosphatase (calcineurin) to inhibit the epidermis fate and a calcium-calmodulin kinase (CaMkinase II) which activates the neural fate is discussed.

Animals↗