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Biomedical subjects

M Landry

Publications and source records attributed to M Landry.

At least 73 records · Page 4Linked to original sources
PubMed1996

Interleukin-11: stimulation in vivo and in vitro by respiratory viruses and induction of airways hyperresponsiveness.

To address the role of IL-11 in viral airways dysfunction, we determined whether infectious agents that exacerbate asthma stimulate stromal cell IL-11 production, determined whether IL-11 could be detected at sites of viral infection and evaluated the effects of IL-11 on airway physiology. Respiratory syncytial virus (RSV), parainfluenza virus type 3 (PIV3), and rhinovirus (RV) 14 were potent stimulators while cytomegalovirus and adenovirus only weakly stimulated and herpes simplex virus type 2 and bacteria did not stimulate IL-11 elaboration. IL-11 was not detected or barely detected in nasal aspirates from children without, but was detected in aspirates from children with viral upper respiratory tract infections. The levels of IL-11 were highest in patients with clinically detectable wheezing. IL-11 also caused nonspecific airways hyperresponsiveness in BALB/c mice. These studies demonstrate that three major causes of viral-induced asthma, RSV, RV, and PIV, in contrast to other viruses and bacteria, share the ability to induce stromal cell IL-11 production. They also demonstrate that IL-11 can be detected in vivo during viral respiratory infections, that the presence of IL-11 correlates with clinical bronchospasm and that IL-11 is a potent inducer of airways hyperresponsiveness. IL-11 may be an important mediator in viral airways disorders.

Animals↗
PubMed1996

[Evaluation of bones using quantitative ultrasonography].

The evaluation of bone by ultrasound is a new, transportable and non-irradiating method. It measures attenuation of ultrasound (BUA), as well as velocity (SOS) of ultrasound in a given tissue. For the measurement of bone, the most frequently used bone is the calcaneus. We have used this technique (Achilles, Lunar) to evaluate the reproducibility of measurements in healthy volunteers and to determine the correlations between the results of ultrasound measurements and those of conventional densitometry (DXA) in a population of postmenopausal females who consulted for screening or diagnosis of osteoporosis. Although several publications have already dealt with the same questions, it is important to reexamine them locally before the technique is uncritically used even in unspecialized centers. The coefficients of variation corresponded to that reported by others: 1.8% for BUA and 0.3% for SOS. The correlations between the ultrasound measurements and the results of DXA at lumbar spine, femoral neck and calcaneus in 57 postmenopausal women aged +/- 59 (43-78) years and in part osteoporotic (DXA results below 2.5 SD-T-score) (Hologic QDR 2000) were all significant (p < 0.001). The best correlation between the two techniques (DEXA and ultrasound) is found when applied to the same site, i.e. the calcaneus (r > 0.8). These results also agree with the literature. Low ultrasound values (BUA < 100 dB/MHz, SOS < 1495 m/s) are highly suggestive of osteoporosis, while high ultrasound values are almost exclusively found in non-osteoporotic women. This information provides the basis for further investigations, such as correlation with fracture risk, in cross-sectional and longitudinal studies.

Absorptiometry, Photon↗
PubMed1996

Computed tomography of the knee joint as an indicator of intraarticular tophi in gout.

OBJECTIVE: To evaluate the utility of computed tomography (CT) of the knee joint for detecting intraarticular tophaceous deposits. METHODS: A prospective study of 16 patients with gout affecting the knee was conducted. A condition for inclusion in the study was the presence of needle-shaped crystals with negative birefringence in the knee joint synovial fluid. Conventional radiography and CT were performed in each case. RESULTS: Intraarticular opacities in the capsule and the synovium, consistent with the presence of tophaceous deposits, were found in 5 of the 16 patients (9 knee joints). The mean duration of gout was longer in the patients with intraarticular tophi than in those without tophi, and 2 of the patients with tophi had poor tolerance to antihyperuricemic therapy. CONCLUSION: Intraarticular opacities considered to represent tophi were observed in approximately one-third of the patients. The presence of tophi correlated with a longer duration of the disease and a poor tolerance to medication. We therefore suggest that CT of the knees could be useful in the assessment and followup of certain patients with gout.

Adult↗
PubMed1996

Enthesopathy and tendinopathy in gout: computed tomographic assessment.

OBJECTIVE: To establish if computed tomography (CT) imaging, which has proved helpful in detecting intra-articular tophi in gout, can also be used to document gouty enthesopathy and tendinopathy. METHODS: Three patients with tophaceous gout and clinical involvement of the Achilles tendon (two cases) or patellar tendon (one case) were assessed with CT examination and plain radiographs. RESULTS: In the first two cases, CT images revealed linear or nodular high attenuation opacities within the substance of the Achilles tendons and their calcaneal insertion. In case 3, dense linear opacities were seen within the patellar tendon and within its tibial insertion. No such opacities of the tendons and entheses were seen on standard radiographs of these patients. CONCLUSIONS: CT appears to be the imaging method of choice for demonstrating monosodium urate deposits in entheses and tendons in tophaceous gout.

Achilles Tendon↗
PubMed1996

Segmental body composition assessed by bioelectrical impedance analysis and DEXA in humans.

The present study assessed the relative contribution of each body segment to whole body fat-free mass (FFM) and impedance and explored the use of segmental bioelectrical impedance analysis to estimate segmental tissue composition. Multiple frequencies of whole body and segmental impedances were measured in 51 normal and overweight women. Segmental tissue composition was independently assessed by dual-energy X-ray absorptiometry. The sum of the segmental impedance values corresponded to the whole body value (100.5 +/- 1.9% at 50 kHz). The arms and legs contributed to 47.6 and 43.0%, respectively, of whole body impedance at 50 kHz, whereas they represented only 10.6 and 34.8% of total FFM, as determined by dual-energy X-ray absorptiometry. The trunk averaged 10.0% of total impedance but represented 48.2% of FFM. For each segment, there was an excellent correlation between the specific impedance index (length2/impedance) and FFM (r = 0.55, 0.62, and 0.64 for arm, trunk, and leg, respectively). The specific resistivity was in a similar range for the limbs (159 +/- 23 cm for the arm and 193 +/- 39 cm for the leg at 50 kHz) but was higher for the trunk (457 +/- 71 cm). This study shows the potential interest of segmental body composition by bioelectrical impedance analysis and provides specific segmental body composition equations for use in normal and overweight women.

Absorptiometry, Photon↗
PubMed1996

The stability of estrogen and progesterone receptors in patients receiving preoperative chemotherapy for locally advanced breast carcinoma.

The determination of estrogen (ER) and progesterone receptor (PR) content is routine in the management of carcinoma of the breast. Such data are commonly used to predict responses to endocrine therapy. Preoperative chemotherapy is often utilized in the treatment of patients with locally advanced carcinoma of the breast. However, little attention has been focused upon the effect of preoperative chemotherapy on hormonal receptor expression in that setting. The purpose of this study is to evaluate the effect of preoperative chemotherapy on ER and PR expression in patients with locally advanced breast carcinoma. Patients with T3 or T4 adenocarcinoma of the breast from Charity Hospital in New Orleans were studied. Levels of ER and PR were determined from tissue blocks obtained at diagnostic biopsy, as well as after the preoperative chemotherapy. The receptor levels were determined using immunohistochemistry and quantified using image analysis. We evaluated 21 locally advanced cancer patients who received at least three cycles of standard chemotherpay regimens. Of these patients, 11 achieved a partial response, with 3 achieving a complete response after preoperative chemotherapy. A total of 33 per cent of patients had a significant change in hormonal receptor content after preoperative chemotherapy. ER changed in 17%, PR in 22%, and both ER and PR in 6%. These data show that ER and/or PR expression changed in 33% of patients studied. Further, ER and PR status does not appear to predict or correlate with response to chemotherapy. This suggests that determination of ER and PR may best be performed from definitive resection specimens in patients who receive preoperative chemotherapy.

Adenocarcinoma↗
PubMed1996

Influences of body weight, body composition, and substrate oxidation rate on resting postabsorptive glucose production and gluconeogenesis.

OBJECTIVE: To determine the influence of body weight, fat mass, and fat distribution on resting endogenous glucose production in healthy lean and overweight individuals. DESIGN: measurements were performed in the resting postabsorptive state in individuals receiving an unrestricted diet. SETTING: Institute of Physiology of Lausanne University. MEASUREMENTS: resting post absorptive glucose production, glycogenolysis and gluconeogenesis; resting energy expenditure and net substrate oxidation. RESULTS: Endogenous glucose production was positively correlated with body weight, lean body mass, energy expenditure and carbohydrate oxidation. Gluconeogenesis was positively correlated with net lipid oxidation and energy expenditure, and negatively correlated with net carbohydrate oxidation. No correlation with body fat or fat distribution was observed. CONCLUSIONS: Gluconeogenesis shows a large interindividual variability. Net lipid oxidation and not body fat appears to be a major determinant of gluconeogenesis.

Adult↗
PubMed1995

[Correlation between arthroscopy and MRI in the diagnosis of meniscal tears of the knee].

The sensibility and specificity of MRI diagnosis of meniscal tears are still debated. We compared the radiologic and arthroscopic diagnosis of 37 patients who underwent MRI study of the knee, followed by arthroscopic surgery. Meniscal lesions were classified according to their size and the grading system of Lotysch and Crues (1). In patients without previous arthroscopic surgery (n = 32), 92% of the grade-3b lesions are found to be torn at surgery. The probability for tears is weaker for grade-3a lesions (one meniscus torn out of three). An intact or slightly degenerated meniscus on MRI (grades 1 and 2) relates in 91% of cases to a normal fibrocartilage at arthroscopy. In patients with previous knee surgery (n = 5), the specificity of MRI for grade-3b lesions is weak (55%), owing to the presence of granulation tissue. Our results agree with those of recent publications, confirming the high value of MRI in the diagnosis of traumatic or degenerative meniscal tears. The use of a grading system incorporating the size of the lesion gives a better specificity to MRI diagnosis.

Adult↗
PubMed1995

Comparison between magnetic resonance imaging and arthroscopy in the diagnosis of patellar cartilage lesions: a prospective study.

A blind and prospective study was conducted to assess the accuracy of magnetic resonance imaging (MRI) for diagnosing patellar cartilage lesions. Thirty-three consecutive patients undergoing knee arthroscopy were examined by MRI prior to surgery. Imaging was performed in the axial plane on a 1.5-Tesla unit with spin-echo and gradient-echo T1 and T2 sequences. The MRI and arthroscopic data were compared using a four-grade classification and a patellar map which divided the patellar surface into four quadrants. The overall sensitivity of MRI was 84.7% and the specificity 97.2%. The same pit-fall led to two MRI false positives. A perfect correlation of grading was obtained in 76.5%. When discordance was found, the tendency with MRI was commonly to underestimate the grade of the lesions. The MRI accuracy was high in this study in spite of a high rate of low-grade lesions which are difficult to assess. Related criteria for cartilage assessment with MRI and arthroscopy are suggested for further studies.

Adolescent↗
PubMed1995

Concha bullosa: frequency and appearances on CT and correlations with sinus disease in 308 patients with chronic sinusitis.

The purposes of this study were to determine the prevalence of concha bullosa in patients with chronic sinusitis, to assess the origin of the pneumatisation (from the anterior or posterior ethmoid cells), and to evaluate the significance of the concha bullosa in the genesis of inflammatory sinus disease. We reviewed the CT studies of 308 patients with chronic sinusitis, assigning four grades of pneumatisation: absent, small, medium and large. Unilateral or bilateral concha bullosa was found in 164 patients (53%). In 79% of cases it was pneumatised via the posterior ethmoidal cells and in 21% via the anterior. A small concha bullosa was associated with abnormalities of the maxillary sinus, ethmoidal cells and ostiomeatal unit respectively in 49%, 28% and 34% of cases, whereas with a large concha bullosa the association was 55%, 36% and 41% respectively on the ipsilateral side and 55%, 32% and 41% on the contralateral side. The usually accepted hypothesis that the concha bullosa may contribute to the pathogenesis of inflammatory sinus disease seems doubtful.

Adult↗
PubMed1995

Lidocaine via iontophoresis in laceration repair: a preliminary safety study.

Iontophoresis is a painless technique for topical anesthesia that uses an electric field to drive charged ions across an epithelial surface. The safety of this technique for laceration repair has never been demonstrated. The purpose of this study was to investigate the effect of iontophoretic fields on rapidly proliferating cells involved in laceration wound healing. The study was a prospective single-blinded animal study using a guinea pig model. Twelve guinea pigs each received four induced, uncontaminated lacerations. Each guinea pig was randomly assigned to 1 of 3 groups (4 guinea pigs in each group). One group received lidocaine via iontophoresis, one group received injected lidocaine, and one group received half iontophoresis and half injected lidocaine. After anesthetic treatment, wounds were then repaired in a standard fashion. The wounds were examined grossly on a daily basis and on day 10 the incised skin containing the laceration was examined by a pathologist blinded to the treatment group. A total of 48 wounds were assessed for wound healing, 24 of which received lidocaine via iontophoresis and 24 lidocaine via injection. The power of the study to determine a 40% difference between the two groups was 0.8. There was significantly more granuloma and granulation tissue formation in the iontophoresis group than in the injected lidocaine control group (P = .0004, Fisher's exact test).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Short-term effects of centrally administered galanin on the hyperosmotically stimulated expression of vasopressin in the rat hypothalamus. An in situ hybridization and immunohistochemistry study.

Galanin (GAL) is a 29-amino acid peptide that is present in the hypothalamic magnocellular neurons of the rat supraoptic nucleus (SON) and paraventricular nucleus (PVN). Since previous studies revealed a possible role of GAL in the hydro-osmotic regulation, we have investigated the effects of GAL on the vasopressin (AVP) mRNA content in the hypothalamic magnocellular neurons. We demonstrated by in situ hybridization (ISH) and immunohistochemistry that 100 pmol of GAL or GAL fragment (1-16) injected into the lateral ventricle of anesthetized dehydrated male rats induced a rapid (10 min time interval) decrease of AVP mRNA and AVP content in the magnocellular cell bodies of SON and PVN. These effects were quantified on an autoradiographic film and were also obvious at the cellular level by using ISH with a radiolabeled or digoxigenin-labeled oligonucleotide probe. Oxytocin mRNA content is not altered by the same injection either in dehydrated male or lactating female rats. Under the same conditions of lactation, AVP mRNA content is not modified and the i.c.v. injection of GAL has no effect. GAL antagonist (M15) injection suppressed the GAL-induced decrease of AVP mRNA in the dehydrated rats and increased AVP mRNA level in control rats. The efficacy of M15 in antagonizing GAL effects on AVP mRNA suggests the involvement of GAL receptors in the regulation of the vasopressinergic cell bodies. Moreover, endogenous GAL seems to depress the AVP mRNA content of SON and PVN in vivo. The possible origin of endogenous GAL and the mechanisms by which GAL can regulate the AVP mRNA content are also discussed.

Animals↗
PubMed1994

Epithelial interleukin-11. Regulation by cytokines, respiratory syncytial virus, and retinoic acid.

Interleukin-11 (IL-11) is a pleiotropic cytokine with effects that overlap with IL-6. To determine if IL-11 is produced by epithelial cells, we determined whether human alveolar A549 cells and airway 9HTE cells produce IL-11. We also determined whether retinoic acid (RA) altered this IL-11 production. Unstimulated cells produced low levels of IL-11, while IL-1, transforming growth factor (TGF-beta 1), and respiratory syncytial virus (RSV) stimulated IL-11 protein production and mRNA accumulation in a time- and dose-dependent fashion. IL-1 and TGF-beta 1 also interacted in a synergistic, and presumedly transcriptional, fashion since they augmented A549 cell IL-11 protein production and mRNA accumulation without altering IL-11 mRNA half-life. In contrast, IL-4 only weakly stimulated, and IL-7, hepatocyte growth factor, and herpes simplex virus Type 2 did not stimulate, IL-11 production. RA did not alter the IL-11 production of unstimulated or RSV infected cells. It did, however, inhibit rIL-1-stimulated and synergistically augment TGF-beta-stimulated IL-11 production. Thus, IL-1, TGF-beta, and RSV stimulate epithelial-like cell IL-11 production, and RA regulates these inductive processes in a stimulus-specific fashion.

Cells, Cultured↗
PubMed1994

Conversion of anterior limb bud cells to ZPA signaling cells in vitro and in vivo.

Following a graft of posterior (zone of polarizing activity or ZPA) cells into the anterior margin of the developing chick wing bud, anterior cells are induced to alter their developmental fate and form structures that are normally composed of posterior cells. When anterior cells are cultured under microdissociation conditions they develop ZPA signaling ability within 24 hr. ZPA signaling in these cultures is transient and once established the level of ZPA signaling declines with time in culture. ZPA signaling in anterior cells is sensitive to treatment with fibroblast growth factor-2 (FGF-2); the development of ZPA signaling is inhibited when nonsignaling anterior cells are cultured in the presence of FGF-2. Conversely, when anterior cells that have developed ZPA signaling are treated with FGF-2, ZPA signaling levels are maintained. Thus, our results suggest that FGF-2 maintains or stabilizes the positional character of anterior (nonsignaling) cells, as well as anterior ZPA signaling converted cells, and posterior (ZPA signaling) limb bud cells in vitro (R. Anderson, M. Landry, and K. Muneoka (1993) Development 117, 1421-1433). In addition, anterior cells will convert to ZPA signaling cells in vivo following apical ectodermal ridge (AER) removal, suggesting that a factor(s) localized to the AER prevents anterior cells from developing ZPA signaling capability during limb outgrowth. These findings indicate that nonsignaling anterior limb bud cells have the potential to become ZPA signaling cells and that FGF-2, or a related factor, functions in the maintenance of positional states in the developing limb.

Animals↗
PubMed1994

[A model of phenotypic plasticity: the hypothalamo-posthypophyseal neurons].

In neurons, which are post-mitotic cells, a structural and biochemical plasticity occurs, namely for the mediators. The magnocellular hypothalamic neurons innervating the neural lobe are a favourable model for the study of the dynamic aspects of neuropeptides expression. In fact, they synthetize these peptides in large amounts, as a function of the physiological or experimental conditions. In addition to the major neuropeptides, oxytocin (OT) and vasopressin (VP) which are contained in control rats within different neuronal populations, immunocytochemistry and in situ hybridization used alone or in combination in the same preparations have revealed other neuropeptides and corresponding mRNAs respectively. These multiple labellings demonstrate that after osmotic stimulation or during lactation some neurons are able to synthetize OT and VP simultaneously, together with galanin and even tyrosine hydroxylase (but not catecholamines). Similarly, hypophysectomy or transection of the pituitary stalk differentially modify the contents in mRNA coding for VP, OT and galanin. These results have also been described in other neuronal types such as spinal ganglia sensory neurons, suggesting possible mechanisms at different levels of genetic expression: transcription, translation, post-translational events and possibly interneuronal exchanges of mRNA. The in vivo regulation of this neurochemical plasticity probably involves the innervation of these neurons and perhaps the colocalized peptides themselves. In fact, galanin selectively inhibits the expression of VP but not that of OT. Functional implications of the neuronal phenotypic plasticity in the adaptation of the nervous system to the changing physiological conditions are discussed, together with its possible implications in pathology and therapeutics.

Humans↗
PubMed1993

Maintenance of ZPA signaling in cultured mouse limb bud cells.

The positional signal localized to the posterior (zone of polarizing activity or ZPA) region of the vertebrate limb is transiently expressed during development and a decline in ZPA signaling is accelerated when posterior cells are dissociated and cultured in vitro. The evidence that cultured posterior cells display a precocious decline in ZPA signaling when compared to in vivo studies suggests that a factor present in the limb bud maintains or stabilizes ZPA signaling during limb outgrowth and that this maintenance factor is lost and/or exhausted in in vitro studies. We have developed a new culture technique, 'microdissociation', which preserves extracellular components that we have found to be necessary for ZPA signal maintenance. Our data suggest that the limb bud ectoderm produces a maintenance activity that becomes stored in the extracellular matrix where it acts on limb bud cells to stabilize the activity of the ZPA signal. Using our initial characterization of this maintenance activity, we have identified a growth factor, FGF-2 (bFGF), that can replace all of the ZPA signaling maintenance activity observed in microdissociate cultures. The existence of various members of the FGF family in the developing limb strongly argues a role for FGF in stabilizing ZPA signaling in vivo.

Animals↗