Dorsal fractures of the triquetrum: MRI findings with an emphasis on dorsal carpal ligament injuries.

OBJECTIVE: The objective of our study was to report the MRI findings in dorsal fractures of the triquetrum, with an emphasis on dorsal carpal ligament injuries. MATERIALS AND METHODS: A total of 21 patients (16 men, five women; mean age, 41.9 years) with acute or subacute (≤ 6 weeks) dorsal triquetral fractures on radiography and MRI were included in this two-center retrospective study. MRI of the wrist was performed on 3-T units with transverse T1-weighted, coronal or transverse (or both) fat-suppressed T2weighted, transverse gadolinium-enhanced fat-suppressed T1-weighted turbo spin-echo, and 3D gadolinium-enhanced fat-suppressed T1-weighted gradient-recalled echo sequences. Three musculoskeletal radiologists evaluated the ulnar styloid process index (USPI) on radiographs and the following MRI features: fracture pattern (types 1-6), bone fragment size and displacement, bone marrow edema distribution, and dorsal carpal ligament tears. RESULTS: Eight type 1, one type 2, six type 3, five type 4, and one type 5 fractures were identified. These fractures were associated with 14 (66.7%), 17 (81.0%), and 16 (76.2%) tears of the dorsal radiocarpal, ulnotriquetral, and intercarpal ligaments, respectively. There was no correlation between bone marrow edema distribution and dorsal carpal ligament injuries (all p > 0.05). The mean (± SD) bone fragment volume and displacement were 205 ± 157 mm(3) and 1.0 ± 1.1 mm, respectively. The mean USPI was 0.21 ± 0.10. CONCLUSION: Dorsal fractures of the triquetrum are frequently associated with dorsal carpal ligament injuries. Bone marrow edema distribution is not correlated with these ligament tears.

New insights into the role of the immune microenvironment in breast carcinoma.

Recently, immune edition has been recognized as a new hallmark of cancer. In this respect, some clinical trials in breast cancer have reported imppressive outcomes related to laboratory immune findings, especially in the neoadjuvant and metastatic setting. Infiltration by tumor infiltrating lymphocytes (TIL) and their subtypes, tumor-associated macrophages (TAM) and myeloid-derived suppressive cells (MDSC) seem bona fide prognostic and even predictive biomarkers, that will eventually be incorporated into diagnostic and therapeutic algorithms of breast cancer. In addition, the complex interaction of costimulatory and coinhibitory molecules on the immune synapse and the different signals that they may exert represent another exciting field to explore. In this review we try to summarize and elucidate these new concepts and knowledge from a translational perspective focusing on breast cancer, paying special attention to those aspects that might have more significance in clinical practice and could be useful to design successful therapeutic strategies in the future.

Large gangliocytic paraganglioma of the duodenum: A rare entity.

Gangliocytic paragangliomas are rare tumors that almost exclusively occur within the second portion of the duodenum. Although these tumors generally have a benign clinical course, they have the potential to recur or metastasize to regional lymph nodes. The case report presented here describes a 57-year-old female patient with melena, progressive asthenia, anemia, and a mass in the second-third portion of the duodenum that was treated by local excision. The patient was diagnosed with a friable bleeding tumor. The histologic analysis showed that the tumor was a 4 cm gangliocytic paraganglioma without a malignant cell pattern. In the absence of local invasion or distant metastasis, endoscopic resection represents a feasible, curative therapy. Although endoscopic polypectomy is currently considered the treatment of choice, it is not recommended if the size of the tumor is > 3 cm and/or there is active or recent bleeding. Patients diagnosed with a gangliocytic paraganglioma should be closely followed-up for possible local recurrence.

Post-collisional Neogene magmatism of the Mediterranean Maghreb margin: a consequence of slab breakoff

A 1 200 km-long linear magmatic belt extends along the Mediterranean coast the Maghreb from Eastern Tunisia to Morocco. This belt is mainly composed of Langan calc-alkaline metaluminous to peraluminous granitoids and associated andesites/cites Central and Eastern Algeria. In Tunisia and Oranie/Western Morocco, calc alkaline activity started later (during the Serravallian) and was followed by the placement of alkali basalts and basanites since the Tortonian to the Pliocene and, in me places, the Pleistocene. Available data on the tectonic setting, petrology, age and biochemistry of this belt show that most of its striking features, e.g. (1) very low magma production rate, subduction-related geochemical imprint, extensive crustal contamination the calc-alkaline magmatism and (2) progressive magmatic change from calc-alkaline alkaline, are consistent with magma generation during a slab breakoff process as proposed Carminati et al, in 1998. The magmatism associated with this breakoff started in Central Eastern Algeria at 16 Ma, then propagated eastwards and westwards, The upward of asthenospheric enriched plume-type mantle through the tear in the downgoing first triggered melting of the overlying lithospheric mantle which had been metasomatised during a previous subduction period. Heat supply from this uprising asthenosphere may have warmed up the continental crust and made its involvement in assimilation processes easier. As the asthenosphere ascended through the `window' in the slab, partial melting occurred at the uprising boundary between asthenosphere and lithosphere, generating basalts with transitional characteristics between those of calc-alkaline and alkaline basalts. As the asthhenospheric upwelling proceeded partial:melting then occurred in the sole asthenospheric mantle, producing alkali basalts. (C) 2000 Academie des sciences Editions scientifiques et medicales Elsevier SAS.

Luteinizing hormone (LH) and prolactin-releasing pituitary tumor: possible malignant transformation of the LH cell line.

A pituitary tumor was diagnosed in a prepubertal 13-yr-old girl, who had elevated plasma LH (58 mIU/ml) and PRL (93 ng/ml) levels; decreased GH, ACTH, and FSH secretion; and diabetes insipidus. After surgery, plasma LH and PRL declined, but not to normal levels. Conventional external radiotherapy to the pituitary was immediately followed by a decrease in LH to prepubertal values (0.7 mIU/ml), while PRL levels became normal only after a long course of bromocriptine therapy. The pituitary tumor was composed of two distinct cell types: small polygonal cells, which were PRL positive by immunohistochemistry, and clusters of pleomorphic large frequently mitotic polynucleated cells, which were LH positive, some of them also being positive for the alpha-subunit or beta LH but not for beta FSH. Four years after surgery and radiotherapy, the patient deteriorated neurologically. Computed tomographic scan showed widespread frontal and periventricular tumor, which had the histological features of a poorly differentiated carcinoma. No PRL, LH, or alpha- or beta-subunits were detectable on immunocytochemistry. While the PRL-positive cells of the pituitary tumor displayed the histological and clinical features of PRL adenomas, the morphological characteristics of LH cells and the sharp decline of plasma LH levels after radiotherapy were suggestive of malignant transformation. In this context, the later brain tumor could have been the result of subependymal spread of the pituitary tumor after it lost its hormone-secreting capacity.

Excision of the Staphylococcal Cassette Chromosome mec (SCCmec) and its crucial role in the horizontal transfer of methicillin resistance in staphylococci.

Staphylococcus aureus est un pathogène humain majeur ayant développé des résistances contre la quasi totalité des antibiotiques disponibles, incluant la très importante famille des β- lactamines. La résistance à cette classe d'antibiotiques est conférée par la « Staphylococcal Cassette Chromosome mec » (SCCmec), qui est un élément génétique mobile capable de s'insérer dans le chromosome bactérien et capable d'être transféré horizontalement chez d'autres staphylocoques. Le mécanisme moléculaire impliqué dans ce transfert horizontal demeure largement inconnu. L'une des premières étapes du transfert est l'excision du SCC mec du chromosome bactérien. Cette excision est promue par des enzymes codées par l'élément SCCmec lui- même et appelées de ce fait « Cassette Chromosome Recombinases » (Ccr). L'un des buts de ce travail de thèse a été de comprendre la régulation de l'expression des gènes codant pour les Ccr recombinases. En utilisant des outils moléculaires originaux, nous avons été en mesure de démontrer en premier lieu que les Ccr recombinases étaient exprimées de façon « bistable », c'est à dire qu'uniquement quelques pourcents de cellules dans une population exprimaient ces gènes à un temps donné. Dans un deuxième temps, nous avons également démontré que l'expression de ces gènes était régulée par des facteurs étrangers au SCC mec. L'expression bistable des recombinases est un concept important. Effectivement, cela permet à la majorité des cellules d'une population de conserver l'élément SCC mec, alors que seulement une petite fraction le perd afin de le rendre disponible pour un transfert. Ainsi, alors que l'élément SCC mec continue de se propager avec la multiplication des bactéries Staphylococcus aureus résistant à la méticilline (SARM), il peut être simultanément transmis à des souches susceptibles (Staphylococcus aureus susceptible à la méticilline, SASM), entraînant l'apparition de nouveaux SARM. De façon très intéressante, le fait que cette bistabilité est contrôlée par les bactéries, et non le SCCmec lui-même, montre que la décision de transférer ou non la cassette SCC mec appartient à la bactérie. En conséquence, il doit exister dans la nature des souches qui sont plus ou moins aptes à effectuer ce transfert. En nous appuyant sur ces observations, nous avons montré que l'excision du SCC mec était effectivement régulée de façon très étroite au cours de la division cellulaire, et ne se passait que pendant un temps limité au début de la croissance. Ce résultat est compatible avec une régulation génétique commandée par la densité cellulaire, qui pourrait être dépendante de la production de signaux extracellulaires, du type que l'on rencontre dans le quorum sensing. Les signaux hypothétiques entraînant l'excision du SCC mec restent inconnus à l'heure actuelle. La connaissance de ces signaux pourrait se révéler très importante afin de développer des stratégies pour interférer avec la dissémination de la résistance au β-lactamines. Deux sujets additionnels ont été logiquement investigués au vu de ces premiers résultats. Premièrement, si certaines souches de SARM sont plus ou moins aptes à déclencher l'excision du SCC mec, de même certaines souches de SASM devraient être plus ou moins aptes à acquérir cet élément. Deuxièmement, afin d'étudier ces mécanismes de transfert au niveau épidémiologique, il nous a été nécessaire de développer des outils nous permettant d'explorer le phénomène à une plus large échelle. Concernant le premier point, il a été postulé que certains SASM seraient réfractaires à l'intégration génomique d'un SCC mec en raison de polymorphismes particuliers à proximité du site d'insertion chromosomique (attB). En étudiant plus de 40 isolais de S. aureus, provenant de porteurs sains, nous avons confirmé ce polymorphisme dans l'environnement à'attB. De plus, nous avons pu montrer que ces régions polymorphiques ont évolué parallèlement à des groupes phylogénétiques bien connus. Ainsi, si des telles régions réfractaires à l'intégration de SCC mec existent, celles-ci devraient ségréger dans des complexes clonaux bien définis qui devraient être facilement identifiables au niveau épidémiologique. Concernant le second point, nous avons été capables de construire un système rapporteur de l'excision du SCCmec, en utilisant un plasmide à faible copie. Ce système consistait en un promoteur fort et un gène codant pour une protéine verte fluorescente (GFP) sous le contrôle d'un promoteur fort séparés à l'aide d'un élément SCC artificiel portant trois terminateurs de transcription. Ainsi, la fluorescence ne s'exprime que si l'élément SCC est excisé du plasmide. Ce système a été testé avec succès dans plusieurs types de staphylocoques, et est actuellement évalué dans d'autres souches et conditions stimulant ou inhibant l'excision. De manière générale, cette dissertation représente parcours scientifique à travers plusieurs aspects d'un problème de santé publique majeur en rapport avec la résistance bactérienne aux antibiotiques. Ce travail s'attaque à des problèmes fondamentaux concernant le transfert horizontal de l'élément SCC mec. De plus, il s'intéresse à des aspects plus généraux de cet élément génétique mobile qui pourraient se révéler très importants en terme de mouvement de gènes au sein des staphylocoques, voir d'autres bactéries gram-positives. Finalement ce travail de thèse met en place le fondamentaux requis pour des recherches futures visant à interférer avec le transfert horizontal de la résistance aux β-lactamines. - Staphylococcus aureus is a major human pathogen. Moreover, S. aureus have developed resistance to almost all available antibiotics, including the important family of β-lactam molecules. Intrinsic resistance to β-lactams is conferred by the Staphylococcal Cassette Chromosome mec (SCCmec), which is a mobile genomic island that inserts into the staphylococcal chromosome and can be horizontally transferred into other staphylococci. However, little is known about the molecular mechanisms involved in this horizontal transfer into naïve strains. One of the first steps in SCC mec horizontal transfer is its excision from the chromosome. Excision is mediated by recombinase enzymes that are encoded by SCC mec itself, and named accordingly Ccr recombinases - for Cassette Chromosome recombinases. One goal of this thesis was to understand the regulation these recombinase genes. By using original molecular tools we could demonstrate first that the Ccr recombinases were expressed in a "bistable" manner, i.e. in only few percentages of the bacterial cells at a given time, and second that they were regulated by determinants that were not encoded on the SCC mec element, but elsewhere on the staphylococcal genome. "Bistable" expression Ccr recombinases is an important concept. It allows SCC mec to be excised and thus available for horizontal transfer, while ensuring that only some cells, but not the whole population, loose their valuable SCC mec genes. Thus, while the SCC mec element expands with the multiplication of the MRSA colony, it can simultaneously be transmitted into methicillin-susceptible S. aureus (MSSA), which convert into new MRSA. Most interestingly, the fact that bistability was regulated by the cells, rather than by SCC mec, indicates that it was the choice of the bacteria to trigger or not SCC mec transfer. As a consequence, there must be, in nature, staphylococcal strains that are more or less prone to sustain SCC mec transfer. Following these seminal observations we found that excision was indeed tightly regulated during bacterial division, and occurred only during a limited period of time at the beginning of bacterial growth. This is compatible with cell-density mediated gene regulation, and may depend on the production of extracellular signal molecules that transmit appropriate orders to neighboring cells, such as in quorum sensing. The potential signal triggering SCCmec excision is as yet unknown. However, it could be critical in promoting the horizontal transfer of methicillin resistance, or for the possible development of means to interfere with it. Two additional hypothesis were logically investigated in the view of these first results. First, if some strains of MRSA might be more prone than others to promote SCC mec excision, then some strains of MS SA might be more or less prone to acquire the element as well. Second, to investigate these multiple mechanisms at an epidemiological level, one would need to develop tools amenable to explore S. aureus strains at a larger scale. Regarding the first issue, it was postulated by others that some MSSA might be refractory to SCC mec integration because they had peculiar DNA polymorphisms in the vicinity of the site-specific chromosomal entry point {attB) of SCC mec. By studying >40 S. aureus isolates from healthy carriers, we confirmed the polymorphism of the attB environment. Moreover, we could show that these polymorphic regions co-evolved with well-known phylogenic clonal clusters. Therefore, if SCCwec-refractory attB environments exist, then they would segregate in well- defined S. aureus clonal clusters that would be easy to identify at the epidemiological level. Regarding the second issue, we were able to construct a new excision reporter system in a low copy number S. aureus plasmid. The reporter system consists in a strong promoter driving a green fluorescent protein {gfp) gene, separated by an artificial SCC-like element carrying three transcriptional terminators. Thus, fluorescence is not expressed unless the SCC-like element is excised. The system has been successfully tested in several aureus and non- aureus staphylococci, and is now being applied to more strains and various excision- triggering or inhibiting conditions. Altogether the dissertation is a scientific journey through various aspects of a salient medical problem with regard to antibiotic resistance and public health threat. The research work tackles fundamental issues about the mechanisms of horizontal transfer of the SCC mec element. Moreover, it also addresses more general features of this mobile element, which could be of larger importance with regard to gene trafficking in staphylococci, and maybe other gram-positive bacteria. Finally, the dissertation sets the fundamentals for future work and possible new ways to interfere with the horizontal transfer of methicillin resistance.

Dynamical features of reaction-diffusion fronts in fractals

The speed of front propagation in fractals is studied by using (i) the reduction of the reaction-transport equation into a Hamilton-Jacobi equation and (ii) the local-equilibrium approach. Different equations proposed for describing transport in fractal media, together with logistic reaction kinetics, are considered. Finally, we analyze the main features of wave fronts resulting from this dynamic process, i.e., why they are accelerated and what is the exact form of this acceleration

Jaffé-Campanacci syndrome: an extremely rare cause of pathologic fracture of the femur

Introduction: Non-ossifying fibromas are common benign bone tumors of children and young adults. They are usually single, asymptomatic and regress spontaneously in adulthood. Some rare cases of pathologic fractures have been described. Jaffé-Campanacci syndrome is the association of multiple non-ossifying fibromas, "café-au-lait" spots and some degree of type 1 neurofibromatosis. While the relationship between the two entities remains unclear, there seems to be some genetic similarities (partial or complete deletion of the gene NF1). Case Report: A 17 yo female patient with a neurofibromatosis type 1 was referred to our tertiary centre with a pathologic fracture of the distal femur through a non-ossifying fibroma. She had a slight mental retardation and "café-au-lait" spots. Imaging revealed multiple typical non-ossifying fibromas of both distal femurs and proximal tibias. There was no impending fracture of the controlateral side, and no other findings on thoraco-abdominal CT scanner. The fracture was treated by minimal invasive plate osteosynthesis. Histological analysis of tissue samples taken during the intervention confirmed the histologic diagnosis of non-ossifying fibroma. The fracture healed eventless and the patient returned to work after 3 months. At 12 months follow-up, the patient remained pain-free. Imaging revealed remodelling of the lesions. Conclusion: Jaffé-Campanacci syndrome is an extremely rare cause of pathologic femur fracture. These fractures can be treated like any other, and good outcome is expected. There is still no consensus in regards to definition of the disease and its relationship with type 1 neurofibromatosis.

Structural alterations of the coronary arterial wall are associated with myocardial flow heterogeneity in type 2 diabetes mellitus.

PURPOSE: To determine the relationship between carotid intima-media thickness (IMT), coronary artery calcification (CAC), and myocardial blood flow (MBF) at rest and during vasomotor stress in type 2 diabetes mellitus (DM). METHODS: In 68 individuals, carotid IMT was measured using high-resolution vascular ultrasound, while the presence of CAC was determined with electron beam tomography (EBT). Global and regional MBF was determined in milliliters per gram per minute with (13)N-ammonia and positron emission tomography (PET) at rest, during cold pressor testing (CPT), and during adenosine (ADO) stimulation. RESULTS: There was neither a relationship between carotid IMT and CAC (r = 0.10, p = 0.32) nor between carotid IMT and coronary circulatory function in response to CPT and during ADO (r = -0.18, p = 0.25 and r = 0.10, p = 0.54, respectively). In 33 individuals, EBT detected CAC with a mean Agatston-derived calcium score of 44 +/- 18. There was a significant difference in regional MBFs between territories with and without CAC at rest and during ADO-stimulated hyperemia (0.69 +/- 0.24 vs. 0.74 +/- 0.23 and 1.82 +/- 0.50 vs. 1.95 +/- 0.51 ml/g/min; p < or = 0.05, respectively) and also during CPT in DM but less pronounced (0.81 +/- 0.24 vs. 0.83 +/- 0.23 ml/g/min; p = ns). The increase in CAC was paralleled with a progressive regional decrease in resting as well as in CPT- and ADO-related MBFs (r = -0.36, p < or = 0.014; r = -0.46, p < or = 0.007; and r = -0.33, p < or = 0.041, respectively). CONCLUSIONS: The absence of any correlation between carotid IMT and coronary circulatory function in type 2 DM suggests different features and stages of early atherosclerosis in the peripheral and coronary circulation. PET-measured MBF heterogeneity at rest and during vasomotor stress may reflect downstream fluid dynamic effects of coronary artery disease (CAD)-related early structural alterations of the arterial wall.

Fourteen new cases contribute to the characterization of the 7q11.23 microduplication syndrome.

Interstitial deletions of 7q11.23 cause Williams-Beuren syndrome, one of the best characterized microdeletion syndromes. The clinical phenotype associated with the reciprocal duplication however is not well defined, though speech delay is often mentioned. We present 14 new 7q11.23 patients with the reciprocal duplication of the Williams-Beuren syndrome critical region, nine familial and five de novo. These were identified by either array-based MLPA or by array-CGH/oligonucleotide analysis in a series of patients with idiopathic mental retardation with an estimated population frequency of 1:13,000-1:20,000. Variable speech delay is a constant finding in our patient group, confirming previous reports. Cognitive abilities range from normal to moderate mental retardation. The association with autism is present in five patients and in one father who also carries the duplication. There is an increased incidence of hypotonia and congenital anomalies: heart defects (PDA), diaphragmatic hernia, cryptorchidism and non-specific brain abnormalities on MRI. Specific dysmorphic features were noted in our patients, including a short philtrum, thin lips and straight eyebrows. Our patient collection demonstrates that the 7q11.23 microduplication not only causes language delay, but is also associated with congenital anomalies and a recognizable face.

Mixed medullary-papillary carcinoma of the thyroid: report of a case and review of the literature.

BACKGROUND: Mixed medullary-follicular thyroid carcinoma denotes a rare and heterogeneous group of tumors displaying morphological and immunophenotypical features of both origins within the same lesion. METHOD: We report a case of a 41-year-old woman with a lump in the right side of the neck, increasing in pain and size over several weeks. Serum levels of calcitonine (1140 ng/L) and carcinoembryonic antigen (288 microg/L) were very high. Fine-needle aspiration cytology suggested a diagnosis of medullary thyroid carcinoma. Total thyroidectomy, along with bilateral functional neck and mediastinal lymph-node dissection, were performed. RESULTS: The histopathological examination yielded a diagnosis of medullary carcinoma in the right thyroid lobe, closely intermingled with a nonencapsulated classical papillary carcinoma. One ipsilateral lymph node showed micrometastasis of the medullary counterpart. CONCLUSION: When compared with other cases reported in literature, this particular presentation should be recognized, if required, morphologic and functional criteria are used. The treatment is mostly surgical, driven by the medullary component. The presence of micrometastasis in 1 ipsilateral cervical lymph-node underlines the importance of cervicomediastinal lymph-node dissection and careful searching for metastatic disease.

Anachronistic facies from a drowned Lower Triassic carbonate platform: Lower member of the Alwa Formation (Ba'id Exotic), Oman Mountains

- The lower member of the Alwa Formation (Lower Olenekian), found within the Ba'id Exotic in the Oman Mountains (Sultanate of Oman), consists of ammonoid-bearing, pelagic limestones that were deposited on an isolated, drowned carbonate platform on the Neotethyan Gondwana margin. The strata contain a variety of unusual carbonate textures and features, including thrombolites, Frutexites-bearing microbialites that contain synsedimentary cements, matrix-free breccias surrounded by isopachous calcite cement, and fissures and cavities filled with large botryoidal cements. Thrombolites are found throughout the study interval, and occur as 0.5-1.0 m thick lenses or beds that contain laterally laterally-linked stromatactis cavities. The Frutexites-bearing microbialites occur less frequently, and also form lenses or beds, up to 30 cm thick; the microbialites may be laminated, and often developed on hardgrounds. In addition, the Frutexites-bearing microbialites also contain synsedimentary calcite cement crusts and botryoids (typically <1 cm thick) that harbour layers or pockets of what appear to be bacterial sheaths and coccoids, and are indicative of biologically mediated precipitation of the cement bodies. Slumping following lithification led to fracturing of the limestone and the precipitation of large, botryoidal aragonite cements in fissures that cut across the primary fabric. Environmental conditions, specifically palaeoxygenation and the degree of calcium carbonate supersaturation, likely controlled whether the thrombolites (high level of calcium carbonate supersaturation associated with vertical mixing of water masses and dysoxic conditions) or Frutexites-bearing microbialites (low level of calcium carbonate supersaturation associated with anoxic conditions and deposition below a stable chemocline) formed. The results of this study point to continued environmental stress in the region during the Early Triassic that likely contributed to the uneven recovery from the Permian-Triassic mass extinction.

The transcriptome of the arbuscular mycorrhizal fungus Glomus intraradices (DAOM 197198) reveals functional tradeoffs in an obligate symbiont.

? The arbuscular mycorrhizal symbiosis is arguably the most ecologically important eukaryotic symbiosis, yet it is poorly understood at the molecular level. To provide novel insights into the molecular basis of symbiosis-associated traits, we report the first genome-wide analysis of the transcriptome from Glomus intraradices DAOM 197198. ? We generated a set of 25,906 nonredundant virtual transcripts (NRVTs) transcribed in germinated spores, extraradical mycelium and symbiotic roots using Sanger and 454 sequencing. NRVTs were used to construct an oligoarray for investigating gene expression. ? We identified transcripts coding for the meiotic recombination machinery, as well as meiosis-specific proteins, suggesting that the lack of a known sexual cycle in G. intraradices is not a result of major deletions of genes essential for sexual reproduction and meiosis. Induced expression of genes encoding membrane transporters and small secreted proteins in intraradical mycelium, together with the lack of expression of hydrolytic enzymes acting on plant cell wall polysaccharides, are all features of G. intraradices that are shared with ectomycorrhizal symbionts and obligate biotrophic pathogens. ? Our results illuminate the genetic basis of symbiosis-related traits of the most ancient lineage of plant biotrophs, advancing future research on these agriculturally and ecologically important symbionts.

Morphological and physiological species-dependent characteristics of the rodent Grueneberg ganglion.

In the mouse, the Grueneberg ganglion (GG) is an olfactory subsystem implicated both in chemo- and thermo-sensing. It is specifically involved in the recognition of volatile danger cues such as alarm pheromones and structurally-related predator scents. No evidence for these GG sensory functions has been reported yet in other rodent species. In this study, we used a combination of histological and physiological techniques to verify the presence of a GG and investigate its function in the rat, hamster, and gerbil comparing with the mouse. By scanning electron microscopy (SEM) and transmitted electron microscopy (TEM), we found isolated or groups of large GG cells of different shapes that in spite of their gross anatomical similarities, display important structural differences between species. We performed a comparative and morphological study focusing on the conserved olfactory features of these cells. We found fine ciliary processes, mostly wrapped in ensheating glial cells, in variable number of clusters deeply invaginated in the neuronal soma. Interestingly, the glial wrapping, the amount of microtubules and their distribution in the ciliary processes were different between rodents. Using immunohistochemistry, we were able to detect the expression of known GG proteins, such as the membrane guanylyl cyclase G and the cyclic nucleotide-gated channel A3. Both the expression and the subcellular localization of these signaling proteins were found to be species-dependent. Calcium imaging experiments on acute tissue slice preparations from rodent GG demonstrated that the chemo- and thermo-evoked neuronal responses were different between species. Thus, GG neurons from mice and rats displayed both chemo- and thermo-sensing, while hamsters and gerbils showed profound differences in their sensitivities. We suggest that the integrative comparison between the structural morphologies, the sensory properties, and the ethological contexts supports species-dependent GG features prompted by the environmental pressure.

Orthotropic active strain models for the numerical simulation of cardiac biomechanics

An active strain formulation for orthotropic constitutive laws arising in cardiac mechanics modeling is introduced and studied. The passive mechanical properties of the tissue are described by the Holzapfel-Ogden relation. In the active strain formulation, the Euler-Lagrange equations for minimizing the total energy are written in terms of active and passive deformation factors, where the active part is assumed to depend, at the cell level, on the electrodynamics and on the specific orientation of the cardiac cells. The well-posedness of the linear system derived from a generic Newton iteration of the original problem is analyzed and different mechanical activation functions are considered. In addition, the active strain formulation is compared with the classical active stress formulation from both numerical and modeling perspectives. Taylor-Hood and MINI finite elements are employed to discretize the mechanical problem. The results of several numerical experiments show that the proposed formulation is mathematically consistent and is able to represent the main key features of the phenomenon, while allowing savings in computational costs.