The effect of sorafenib on liver regeneration and angiogenesis after partial hepatectomy in rats.

BACKGROUND: Liver regeneration is vital for the survival of patients submitted to extensive liver resection as a treatment of hepatocellular carcinoma (HCC). Sorafenib is a multikinase inhibitor of angiogenesis and cell division, both of which are integral components of liver regeneration. We investigated the effect of preoperative treatment with sorafenib, a drug used for the treatment of HCC, on liver regeneration and angiogenesis in healthy rats, after two-thirds partial hepatectomy (PH2/3). METHODS: In total 48 Wistar rats received intragastric injections of sorafenib (30 mg/kg/d) or vehicle, underwent PH2/3, and were sacrificed at 48, 96 or 168 hours after that. The regenerative index of the liver remnant was studied, as well as the mitotic index. DNA synthesis and angiogenesis were estimated by immunohistochemistry for the Ki-67 and CD34 antigens, respectively. RESULTS: Sorafenib reduced significantly the regenerative index at all time points but not the mitotic index at 48, 96 or 168 hours. Deoxyribonucleic acid (DNA) synthesis and angiogenesis were not affected significantly either. CONCLUSIONS: Sorafenib, when administered preoperatively, reduces incompletely and transiently the regeneration of the liver after PH2/3 in rats. This could mean that sorafenib can be used as neoadjuvant treatment of patients with HCC prior to liver resection, but further experimental and clinical studies are needed to establish the safety of this treatment. Hippokratia 2015; 19 (3): 249-255.

Non-invasive stimulation of the vibrissal pad improves recovery of whisking function after simultaneous lesion of the facial and infraorbital nerves in rats.

We have recently shown that manual stimulation of target muscles promotes functional recovery after transection and surgical repair to pure motor nerves (facial: whisking and blink reflex; hypoglossal: tongue position). However, following facial nerve repair, manual stimulation is detrimental if sensory afferent input is eliminated by, e.g., infraorbital nerve extirpation. To further understand the interplay between sensory input and motor recovery, we performed simultaneous cut-and-suture lesions on both the facial and the infraorbital nerves and examined whether stimulation of the sensory afferents from the vibrissae by a forced use would improve motor recovery. The efficacy of 3 treatment paradigms was assessed: removal of the contralateral vibrissae to ensure a maximal use of the ipsilateral ones (vibrissal stimulation; Group 2), manual stimulation of the ipsilateral vibrissal muscles (Group 3), and vibrissal stimulation followed by manual stimulation (Group 4). Data were compared to controls which underwent surgery but did not receive any treatment (Group 1). Four months after surgery, all three treatments significantly improved the amplitude of vibrissal whisking to 30° versus 11° in the controls of Group 1. The three treatments also reduced the degree of polyneuronal innervation of target muscle fibers to 37% versus 58% in Group 1. These findings indicate that forced vibrissal use and manual stimulation, either alone or sequentially, reduce target muscle polyinnervation and improve recovery of whisking function when both the sensory and the motor components of the trigemino-facial system regenerate.

Recovery of whisking function after manual stimulation of denervated vibrissal muscles requires brain-derived neurotrophic factor and its receptor tyrosine kinase B.

Functional recovery following facial nerve injury is poor. Neuromuscular junctions (NMJs) are "bridged" by terminal Schwann cells and numerous regenerating axonal sprouts. We have shown that this poly-innervation of NMJs can be reduced by manual stimulation (MS) with restoration of whisking function. In addition, we have recently reported that insulin-like growth factor-1 (IGF-1) is required to mediate the beneficial effects of MS. Here we extend our findings to brain derived neurotrophic factor (BDNF). We then examined the effect of MS after facial-facial anastomosis (FFA) in heterozygous mice deficient in BDNF (BDNF(+/-)) or in its receptor TrkB (TrkB(+/-)). We quantified vibrissal motor performance and the percentage of NMJ bridged by S100-positive terminal Schwann cells. In intact BDNF(+/-) or TrkB(+/-) mice and their wild type (WT) littermates, there were no differences in vibrissal whisking nor in the percentage of bridged NMJ (0% in each genotype). After FFA and handling alone (i.e. no MS) in WT animals, vibrissal whisking amplitude was reduced (60% lower than intact) and the percentage of bridged NMJ increased (27% more than intact). MS improved both the amplitude of vibrissal whisking (not significantly different from intact) and the percentage of bridged NMJ (11% more than intact). After FFA and handling in BDNF(+/-) or TrkB(+/-) mice, whisking amplitude was again reduced (53% and 60% lower than intact) and proportion of bridged NMJ increased (24% and 29% more than intact). However, MS failed to improve outcome in both heterozygous strains (whisking amplitude 55% and 58% lower than intact; proportion of bridged NMJ 27% and 18% more than intact). We conclude that BDNF and TRkB are required to mediate the effects of MS on target muscle reinnervation and recovery of whisking function.

Histological alterations of the human myocardium during minimally invasive direct coronary artery bypass operation

To study the ischaemia caused to myocardial cells during the Minimally Invasive DirectCoronary Artery Bypass (MIDCAB) procedure,ten patients underwent surgical revascularizationof the anterior descending artery using the MIDCAB technique. During the anastomosis, the left anterior descending (LAD) was snared with two sutures 4-0 prolene.The time of ischaemia was 13-22 min (mean 16.4 min). Three biopsies were taken from the anteroapical part of the left ventricle: a) Prior to the ischaemia b) At the end of theischaemic period c) 25 minutes after bloodflow had been restored. The degree of cellular and perivascular damage was studied by electron microscopy.Simultaneously, an electrocardiogram (ECG)was performed and the biochemical markers of myocardial ischaemia were measured.There were no deaths or myocardial infarctions.Slight ischaemic changes were found in all tissue samples before occlusion of the LAD. A semiquantitative analysis showed that a large percentage of myocytes (83.5-90%) in all phases were normal or only slight changes. A few myocytes (3-6%) were severely or irreversibly damaged. The morphometric analysisof mitochondrial oedema revealed no statisticallysignificant differences. In conclusion, the MIDCAB technique can be applied for the surgical revascularization of the LAD without significant ischaemic changes to the myocardial cells (AU)

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Hypoxic pretreatment protects against neuronal damage of the rat hippocampus induced by severe hypoxia.

The present study investigates whether under conditions of successive hypoxic exposures pretreatment with mild (15% O(2)) or moderate (10% O(2)) hypoxia, protects hippocampal neurones against damage induced by severe (3% O(2)) hypoxia. The ultrastructural findings were also correlated with regional superoxide dismutase (SOD) activity changes. In unpretreated rats severe hypoxia induced ultrastructural changes consistent with the aspects of delayed neuronal death (DND). However, in preexposed animals hippocampal damage was attenuated in an inversely proportional way with the severity of the hypoxic pretreatment. The ultrastructural hypoxic tolerance findings were also closely related to increased regional SOD activity levels. Thus the activation of the endogenous antioxidant defense by hypoxic preconditioning, protects against hippocampal damage induced by severe hypoxia. The eventual contribution of increased endogenous adenosine and/or reduced excitotoxicity to induce hypoxic tolerance is discussed.

Dentinogenic activity of allogenic plasma fibronectin on dog dental pulp.

The response of ectomesenchymal cells of dog dental pulp to implantation of Millipore filters supplemented with bovine plasma fibronectin was evaluated after observation periods of one or four weeks. Two concentrations of plasma fibronectin were used (0.2 and 1 mg/mL). Experiments also included implants treated with control solutions (PBS or 1 mg/mL of dog albumin). Formation of a layer of elongated, polarized cells was demonstrated in direct contact with the implants treated with 1 mg/mL of plasma fibronectin solution, after one week post-operatively. Microfilamentous organization and orientation of rough endoplasmic reticulum was observed mainly in the supranuclear zone of the polarized cells. Implants treated with the same solution were consistently surrounded by a thick layer of dentinal matrix after four weeks of their exposure to pulp sites. Implants treated with control solutions or with the low concentration of fibronectin never showed any sign of cell polarization and matrix synthesis. These data provide evidence that the pulp cells can express their odontoblastic phenotype in response to a surface containing concentrated fibronectin (even allogenic), without the need of other molecules as exogenous inductive factors.

Short-term dentinogenic response of dog dental pulp tissue after its induction by demineralized or native dentine, or predentine.

The events initiating the expression of odontoblastic potential by pulpal ectomesenchymal cells were investigated by exposing the pulp to demineralized, native and unmineralized autogenous dentine. The pulp responses to implants were histologically evaluated 3, 7 and 10 days postoperatively, while the surface structure of the newly mineralized matrices was examined 12 and 28 days after implantation. Differentiation of odontoblast-like cells in close proximity to the implanted matrix was consistently demonstrated after exposure to predentine. Scattered columnal cells undergoing polarization, characterized ultrastructurally by the orientation of their rough endoplasmic reticulum, were also found in direct contact with the demineralized dentine. However, in response to demineralized implants, groups of differentiated odontoblast-like cells were clearly seen only in association with a zone of matrix secreted in a polar, predentine-like pattern, indicating an asynchronous inductive influence of this type of implant on pulp cells. Further, the response of pulp cells to native dentine was characterized by the elaboration of a two-layered matrix (a fibrous and a polarly deposited matrix) before initiation of secondary dentinogenesis. Scanning electron microscopy of the newly deposited matrices revealed differences between the indirect matrix synthesis, observed in short-term response to implants of demineralized or native dentine, and the specific, dentinogenic function of the odontoblast-like cells. These observations indicate that the dentine-induced dentinogenesis is initiated by two mechanisms--direct induction of odontoblast-like cells as well as indirect matrix synthesis, which further controls cell polarization. Immobilization of the cells on implanted matrix seems to be the critical requirement for direct expression of the odontoblastic phenotype.

Ultrastructural study of bronchial epithelium in chronic respiratory diseases.

The fine structure of bronchial epithelium in thirty-six patients, thirty-one men and five women, suffering from chronic obstructive pneumonopathy or bronchial carcinoma was studied. No remarkable alterations were found with electron microscopy, in most non-smokers in contrast to the smokers who presented destruction of the epithelial cells and loss of the cilia or many pathological cilia with an abnormal microtubular configuration and irregular orientation. The severity, however, of the alterations was not related to the severity of smoking and to the presence of bronchial cancer.

Ultrastructure of the rat hippocampus after isobaric respirative hyperoxia.

After exposing rats to an environment of isobaric hyperoxia, the ultrastructural alterations of the hippocampus were studied. No major alterations were found in the nerve cells. Of importance was the moderate osmiophilia and the spindle-like transformation of the mitochondria. Vacuolated synapses and neuraxons were found, containing amorphous material. Astrocytic perivascular end feet were found vacuolated in many places. Many endothelial cells of the capillaries presented high osmiophilia, which sometimes prevented structural details. Quantitatively, the findings were proportionally related to the time of exposure in the pure oxygen atmosphere (24, 48 and 65 hours).