Immunolocalization of laminin, heparan-sulfate proteoglycan, entactin, and type IV collagen in the rat anterior pituitary. I. An in vivo study.

The distribution of three components of basement membranes (BM): heparan-sulfate proteoglycan (HSPG), entactin (ENT), and type IV collagen (Coll. IV), was studied in the adult rat anterior pituitary and compared to the distribution of laminin (LAM) described in an earlier report (Vila-Porcile et al., 1987, J. Histochem. Cytochem., 35, 287). Several immunocytochemical methods were applied at both light and electron microscope levels. The three components were detected in all the pituitary BM and in endothelial and perivascular connective cells, as previously observed for LAM. In contrast to the prominent labeling previously observed for LAM within epithelial cells, however, only a faint immunoreaction could be detected for the other components, with nonetheless a discrete signal for Coll. IV. These findings indicate that 1) the four studied components are present in all the BM of the rat anterior pituitary; 2) pituitary endocrine cells contain LAM, and to a lesser extent Coll. IV, and thus could participate to the elaboration of the BM; and 3) the presence of the four components in non-epithelial cells also suggests their cooperation in BM building. The questions of the turnover and intracellular pathways of each of these components were addressed but remain unanswered.     

Centric relation and programming semiadjustable articulators with the universal jig. Part I: Technique

To obtain centric relation and program recordings, a universal jig was made to be molded after adjustment to the upper incisors by means of dental plaster. The jig can be produced by means of an autopolymerizing resin mold based on the wax model. Once the jig is in position, the patient is asked to produce left and right lateral movements until muscular relaxation is obtained. This allows centric relation to be recorded by whatever method use. After plaster has been injected on the occlusal surfaces of the teeth, the patient is asked to close his jaws on the jig and to perform either a propulsion movement or left- or right-lateral movement so as to obtain two plaster "bites" ready for the programming of semiajustable articulators.     

Intravenous diltiazem versus nitroglycerin for silent and symptomatic myocardial ischemia in unstable angina pectoris

For 18 patients consecutively admitted to the coronary care unit for unstable angina, 48-hour electrocardiographic Holter monitoring was performed after they were randomly assigned in a single-blind fashion to 1 of 2 treatment groups. The first group was treated with acetylsalicylic acid (ASA) and intravenous nitroglycerin, the second with ASA and intravenous diltiazem. All of the patients treated with nitroglycerin still had ischemic episodes after 48 hours (33% were symptomatic), in contrast with 11% of the diltiazem group (11% asymptomatic). Maximal ST-segment depressions of symptomatic and asymptomatic episodes were significantly different; and no significant increases in heart rate were observed either during the 15 seconds before ischemia began or during the ischemic episode. During the 48 hours, the diltiazem group had significantly fewer ischemic episodes (17) than did the nitroglycerin group (145). We concluded that "on-line" ST-segment observation is of prime importance for monitoring unstable angina; that the majority of the ischemic episodes associated with unstable angina are silent; and that intravenous diltiazem could be an effective pretreatment for patients who must undergo mechanical or surgical therapy.     

In vitro action of hypothalamic luteinizing hormone releasing factor (IRF) on lamb anterior pituitary. II. Ultrastructural study of incubated tissues

The ultrastructural evolution of ewe-lamb pituitary slices incubated as function of time (30 min, 60 min, 90 min, 2 hr, 3 hr, 4 hr, 8 hr and 24 hr) was studied in absence or presence of a purified hypothalamic luteinizing hormone releasing factor (LRF) and in one case in the presence of a brain cortex extract. High resolution autoradiography was utilized in order to appreciate the protein synthesis ability of the cells.     

Effect of RGD functionalization and stiffness modulation of polyelectrolyte multilayer films on muscle cell differentiation

Skeletal muscle tissue engineering holds promise for the replacement of muscle damaged by injury and for the treatment of muscle diseases. Although arginylglycylaspartic acid (RGD) substrates have been widely explored in tissue engineering, there have been no studies aimed at investigating the combined effects of RGD nanoscale presentation and matrix stiffness on myogenesis. In the present work we use polyelectrolyte multilayer films made of poly(l-lysine) (PLL) and poly(l-glutamic) acid (PGA) as substrates of tunable stiffness that can be functionalized by a RGD adhesive peptide to investigate important events in myogenesis, including adhesion, migration, proliferation and differentiation. C2C12 myoblasts were used as cellular models. RGD presentation on soft films and increasing film stiffness could both induce cell adhesion, but the integrins involved in adhesion were different in the case of soft and stiff films. Soft films with RGD peptide appeared to be the most appropriate substrate for myogenic differentiation, while the stiff PLL/PGA films induced significant cell migration and proliferation and inhibited myogenic differentiation. ROCK kinase was found to be involved in the myoblast response to the different films. Indeed, its inhibition was sufficient to rescue differentiation on stiff films, but no significant changes were observed on stiff films with the RGD peptide. These results suggest that different signaling pathways may be activated depending on the mechanical and biochemical properties of multilayer films. This study emphasizes the advantage of soft PLL/PGA films presenting the RGD peptide in terms of myogenic differentiation. This soft RGD-presenting film may be further used as a coating of various polymeric scaffolds for muscle tissue engineering.     

Clinical and pathological impact of an optimal assessment of brain invasion for grade 2 meningioma diagnosis: lessons from a series of 291 cases

Brain invasion has not been recognized as a standalone criterion for atypical meningioma by the WHO classification until 2016. Since the 2007 edition suggested that meningiomas harboring brain invasion could be classified as grade 2, brain invasion study was progressively strengthened in our center, based on a strong collaboration between neurosurgeons and neuropathologists regarding sample orientation and examination. Practice changes were considered homogeneous enough in 2011. The aim of the present study was to evaluate the impact of gross practice change on the clinical and pathological characteristics of intracranial meningiomas classified as grade 2.

The characteristics of consecutive patients with a grade 2 meningioma surgically managed before (1998–2005, n?=?125, group A) and after (2011–2014, n?=?166, group B) practices changed were retrospectively reviewed.

Sociodemographical and clinical parameters were comparable in groups A and B, and the median age was 62 years in both groups (p?=?0.18). The 5-year recurrence rates (23.2% vs 29.5%, p?=?0.23) were similar. In group A, brain invasion was present in 48/125 (38.4%) cases and was more frequent than in group B (14/166, 8.4%, p?<?0.001). In group A, 33 (26.4%) meningiomas were classified as grade 2 solely based on brain invasion (group A_SBI), and 92 harbored other grade 2 criteria (group A_OCA). Group A_SBI meningiomas had a similar median progression-free survival compared to groups A_OCA (68 vs 80 months, p?=?0.24) and to A_OCA and B pooled together (n?=?258, 68 vs 90 months, p?=?0.42).

An accurate assessment of brain invasion is mandatory as brain invasion is a strong predictor of meningioma progression.

     

The effect of delivering the chemokine SDF-1α in a matrix-bound manner on myogenesis

Several chemokines are important in muscle myogenesis and in the recruitment of muscle precursors during muscle regeneration. Among these, the SDF-1α chemokine (CXCL12) is a potent chemoattractant known to be involved in muscle repair. SDF-1α was loaded in polyelectrolyte multilayer films made of poly(l-lysine) and hyaluronan to be delivered locally to myoblast cells in a matrix-bound manner. The adsorbed amounts of SDF-1α were tuned over a large range from 100 ng/cm² to 5 μg/cm², depending on the initial concentration of SDF-1α in solution, its pH, and on the film crosslinking extent. Matrix-bound SDF-1α induced a striking increase in myoblast spreading, which was revealed when it was delivered from weakly crosslinked films. It also significantly enhanced cell migration in a dose-dependent manner, which again depended on its presentation by the biopolymeric film. The low-crosslinked film was the most efficient in boosting cell migration. Furthermore, matrix-bound SDF-1α also increased the expression of myogenic markers but the fusion index decreased in a dose-dependent manner with the adsorbed amount of SDF-1α. At high adsorbed amounts of SDF-1α, a large number of Troponin T-positive cells had only one nucleus. Overall, this work reveals the importance of the presentation mode of SDF-1α to emphasize its effect on myogenic processes. These films may be further used to provide insight into the role of SDF-1α presented by a biomaterial in physiological or pathological processes.     

Manipulation of the adhesive behaviour of skeletal muscle cells on soft and stiff polyelectrolyte multilayers

Polyelectrolyte multilayer coatings have emerged as substrates to control a variety of cell behaviour, including adhesion, proliferation and differentiation. In particular, it is possible to modulate film stiffness by physical or chemical cross-linking. In this study, we evaluate the adhesive behaviour of skeletal muscle cells (C2C12 myoblasts) during the initial steps of spreading on layer-by-layer films of controlled stiffness made of poly(l-lysine) and hyaluronan as model biomaterial surfaces for muscle tissue engineering. We show that integrin clustering, integrin actin cytoskeleton connection and focal adhesion formation for cell spreading can be decoupled by controlling film stiffness. This made it possible to switch the cells morphologically between round and spreading shapes depending on the stiffness of the microenvironment. Although hyaluronan is one of the main components of cross-linked multilayer films, the HA receptor CD44 did not appear to mediate early adhesion as suggested by the use of blocking antibodies. In contrast, integrins were found to play a pivotal role in early adhesion: their activation significantly enhanced C2C12 myoblast spreading on soft films, where they were otherwise round. Integrin clustering was also induced by the softer films and enhanced on the stiffest films. Conversely, the use of soluble inhibitors or blocking antibodies directed against integrins induced a round phenotype on stiff films, where cells were well spread out in control conditions. We show that specific integrins were involved in the adhesion process as blocking β₃, but not β₁, integrins inhibited cell adhesion. These soft, stiff films can thus be used to tune the adhesion of C2C12 myoblasts, an early key event in myogenesis, via integrin clustering and subsequent signalling. They may be further used to decorticate the signalling pathways associated with β₃ integrins.