Histology and histopathology Vol.25, nº9 (2010)

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Standard bone healing stages occur during delayed bone healing, albeit with a different temporal onset and spatial distribution of callus tissues
(Murcia: F. Hernández, 2010) Peters, Anja; Schell, Hanna; Bail, Hermann J.; Hannemann, Marion; Schumann, Tanja; Duda, Georg N.; Lienau, Jasmin
Bone healing is considered as a recapitulation of a developmental program initiated at the time of injury. This study tested the hypothesis that in delayed bone healing the regular cascade of healing events, including remodeling of woven to lamellar bone, would be similar compared to standard healing, although the temporal onset would be delayed. A tibial osteotomy was performed in sheep and stabilized with a rotationally unstable fixator leading to delayed healing. The sheep were sacrificed at 2, 3, 6, 9 weeks and 6 months postoperatively. The temporal and spatial tissue distributions in the calluses and the bone microstructure were examined by histology. Although histological analysis demonstrated temporal and spatial callus tissue distribution differences, delayed healing exhibited the same characteristic stages as those seen during uneventful standard healing. The delayed healing process was characterized by a prolonged presence of hematoma, a different spatial distribution of new bone and delayed and prolonged endochondral bone formation. A change in the spatial distribution of callus formation was seen by week 6 leading to bone formation and resorption of the cortical bone fragments, dependent on the degree to which the cortical bone fragments were dislocated. At 6 months, only 5 out of 8 animals showed complete bony bridging with a continuous periosteum, although lamellar bone and newly formed woven bone were present in the other 3 animals. This study demonstrates that during delayed bone healing all stages of the healing cascade likely take place, even if bony consolidation does not occur. Furthermore, the healing outcome might be related to the periosteum’s regenerative capacity leading to bony union or absence of bony bridging.
Open Access
Molecular mechanisms of gap junction mutations in myelinating cells
(Murcia : F. Hernández, 2010) Sargiannidou, Irene; Markoullis, Kyriaki; Kleopa, Kleopas A.
There is an emerging group of neurological disorders that result from genetic mutations affecting gap junction proteins in myelinating cells. The X-linked form of Charcot Marie Tooth disease (CMT1X) is caused by numerous mutations in the GJB1 gene encoding the gap junction protein connexin32 (Cx32), which is expressed in both Schwann cells in the PNS and oligodendrocytes in the CNS. Patients with CMT1X present mainly with a progressive peripheral neuropathy, showing mixed axonal and demyelinating features. In many cases there is also clinical or subclinical involvement of the CNS with acute or chronic phenotypes of encephalopathy. Furthermore, mutations in the GJA12/GJC2 gene encoding the gap junction protein Cx47, which is expressed in oligodendrocytes, have been identified in families with progressive leukodystrophy, known as Pelizaeus-Merzbacher-like disease, as well as in patients with hereditary spastic paraplegia. Recent studies have provided insights into the pattern of gap junction protein expression and function in CNS and PNS myelinating cells. Furthermore, in vitro and in vivo disease models have clarified some of the molecular and cellular mechanisms underlying these disorders. Here we provide an overview of the clinical, genetic, and neurobiological aspects of gap junction disorders affecting the nervous system.
Open Access
EGFR expression and activation are common in HER2 positive and triple-negative breast tumours
(Murcia : F. Hernández, 2010) Koletsa, T.; Kotoula, Vassiliki; Karayannopoulou, Georgia; Nenopoulou, E.
EGFR has been associated with unfavourable prognosis in patients with triple-negative breast carcinomas, although little is known about EGFR activation in these tumours. In a series of breast carcinomas (archived formalin fixed tumours, n=100), we investigated EGFR phosphorylation status at Tyr992 (pEGFR-Y992) and Tyr1068 (pEGFR-Y1068) by immunohistochemistry, along with EGFR protein expression (extracellular domain), gene amplification status (fluorescent in situ hybridization) and conventional clinicopathologic parameters. EGFR protein was present in 21.9%, while phosphorylation at Y1068 and Y992 was observed in 27.8% and 50.5% of tumours, respectively. None of the tumours showed EGFR gene amplification, whereas 21.1% exhibited chromosome 7 polysomy. The above EGFR parameters were usually not simultaneously detected and were not associated with each other. High grade (p=0.003), lymph node positive (p=0.045), estrogen receptor (ER) negative (p<0.001) tumours often expressed EGFR protein. EGFR-Y992 and Y1068 phosphorylation was inversely associated with ER presence (p=0.023 and p=0.029, respectively) but positively with HER2 expression status (p<0.001 and p=0.002, respectively). The global positivity for any EGFR parameter did not significantly differ between triple-negative and HER2 positive tumours. In conclusion, EGFR phosphorylation is commonly encountered in breast carcinomas, although unrelated to EGFR protein presence and gene amplification. EGFR may appear activated even in cases where the extracellular domain of this protein is not observed with immunohistochemistry. These findings may be useful for further studies aiming at the assessment of EGFR parameters on this type of material
Open Access
A role for mammalian target of rapamycin -mTOR- pathway in non alcoholic steatohepatitis related-cirrhosis
(Murcia : F. Hernández, 2010) Kubrusly, Márcia Saldanha; Corrêa-Giannella, Maria Lúcia; Bellodi-Privato, Marta; de Sá, Sandra Valéria; Cauduro Soares, Iberê; Wakamatsu, Alda; Avancini Ferreira Alves, Venâncio; Giannella-Neto, Daniel; Bacchella, Telesforo; Cerqueira Cesar Machado, Marcel; Carneiro D’Albuquerque, Luiz Augusto; Pinto Marques Souza de Oliveira, Claudia
Summary. Non-alcoholic fatty liver disease (NAFLD) encompasses the whole spectrum of steatosis, nonalcoholic steatohepatitis (NASH), and NASH-related cirrhosis (NASH/Cir). Although molecular advances have been made in this field, the pathogenesis of NAFLD is not completely understood. The gene expression profiling associated to NASH/Cir was assessed, in an attempt to better characterize the pathways involved in its etiopathogenesis. Methods: In the first step, we used cDNA microarray to evaluate the gene expression profiles in normal liver (n=3) and NASH/Cir samples (n=3) by GeneSifter™ analysis to identify differentially expressed genes and biological pathways. Second, tissue microarray was used to determine immunohistochemical expression of phosphorylated mTOR and 4E-BP1 in 11 normal liver samples, 10 NASH/Cir samples and in 37 samples of cirrhosis of other etiologies to further explore the involvement of the mTOR pathway evidenced by the gene expression analysis. Results: 138 and 106 genes were, respectively, up and down regulated in NASH/Cir in comparison to normal liver. Among the 9 pathways identified as significantly modulated in NASH/Cir, the participation of the mTOR pathway was confirmed, since expression of cytoplasmic and membrane phosphomTOR were higher in NASH/Cir in comparison to cirrhosis of other etiologies and to normal liver. Conclusions: Recent findings have suggested a role for the cellular “nutrient sensor” mTOR in NAFLD and the present study corroborates the participation of this pathway in NASH/Cir. Phospho-mTOR evaluation might be of clinical utility as a potential marker for identification of NASH/Cir in cases mistakenly considered as cryptogenic cirrhosis owing to paucity of clinical data.
Open Access
Morphologic changes and methodological issues in the rabbit experimental model for diaphragmatic hernia
(Murcia : F. Hernández, 2010) Roubliova, Xenia I.; Deprest, Jan A.; Biard, Jean Marc; Ophalvens, Lieve; Gallot, Denis; Jani, Jacques C.; Van de Ven, Cornelis P.; Tibboel, Dick; Verbeken, Erik K.
Summary. Fetal lung development may be impaired by some congenital anomalies or in utero events. Animal models are used to understand the pathophysiology of these diseases and explore therapeutic strategies. Our group has an interest in the prenatal management of congenital diaphragmatic hernia (CDH). Isolated CDH remains associated with a 30% mortality because of lung hypoplasia and pulmonary hypertension. On day 23 of gestation (pseudoglandular stage) CDH was created in both ovarian-end fetuses (n=28) in 14 time-mated pregnant white rabbits (hybrid of Dendermonde and New-Zealand White). At term (day 30) all survived operated fetuses and size-matched controls were harvested. Fetuses/lungs were assigned randomly to formalin fixation either under pressure of 25 cm H2O (CDH25 n=5; CTR25 n=5) or without (0 cm H2O (CDH0 n=7; CTR0 n=7). Fetuses and lungs were first weighed, and then the lungs were processed for morphometry. Pulmonary development was evaluated by lung-to-body weight ratio (LBWR) and airway and vascular morphometry. Surgical induction of CDH does reduce the LBWR to hypoplastic levels. The contralateral lung weight is 81% of what is expected, whereas the ipsilateral lung is only 46% of the normal. This was accompagnied by a loss of conducting airway generations, precisely, terminal bronchioles (TB), which were surrounded by less alveoli. The ipsilateral CDH lung demonstrated a thickened media in the peripheral arteries as well. As a result, in the severely hypoplastic ipsilateral lung, an airway fixation pressure of 25 H2O has no significant effect on the morphometric indices. The contralateral lung has a normal amount of alveoli around a single TB, which also behave like alveoli of the normal lung, i.e. expand under pressure fixation. The present study on severely hypoplastic lungs that never respirated, shows that in contrast to normal lungs, the morphometric indices are not significantly influenced by a difference in fixation pressure. Increasing fixation pressure seems to expand the lung only when sufficient alveolated parenchyma is present.

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