Mild synthesis of poly(HEMA)-networks as well-defined nanoparticles in supercritical carbon dioxide.

Free-radical dispersion polymerisation of 2-hydroxyethyl methacrylate was carried out in supercritical carbon dioxide (scCO2) in the presence of stabilisers based on polyethylene oxide (PEO) and poly(heptadecafluorodecyl acrylate) (PFDA). Different architectures of copolymers (random, palm-tree and diblock) were tested for their surface tension, cloud point and as a stabilising agent. The diblock architecture was found to be the best candidate resulting in poly(HEMA) spherical particles with a size of 316 nm. Furthermore, the effect of the CO2-phobic block (PEO) in the diblock architecture was investigated by using three different chain lengths (1000, 2000, 5000 g mol-1). By optimizing the stabiliser composition and structure, mild reaction conditions have been identified allowing us to obtain well-defined spherical cross-linked poly(HEMA) particles with a mean diameter of unprecedented low size (216 nm) at a temperature as low as 35 °C.

EGFR/TGFα and TGFß/CTGF Signaling in Neuroendocrine Neoplasia: Theoretical Therapeutic Targets.

Neuroendocrine neoplasms (NENs) are a heterogeneous family of malignancies whose proliferation is partially dependent on growth factors secreted by the microenvironment and the tumor itself. Growth factors which were demonstrated to be important in experimental models of NENs include EGF (epidermal growth factor), TGF (transforming growth factor) α, TGFß and CTGF (connective tissue growth factor). EGF and TGFα bind to the EGF receptor to stimulate an intact RAS/RAF/MAPK pathway, leading to the transcription of genes associated with cell proliferation, invasion and metastasis. Theoretically, TGFα stimulation can be inhibited at several points of the MAPK pathway, but success is limited to NEN models and is not evident in the clinical setting. TGFß1 stimulates TGFß receptors (TGFßRI and TGFßRII) resulting in inhibition of neuroendocrine cell growth through SMAD-mediated activation of the growth inhibitor P21(WAF1/CIP1). Although some NENs are inhibited by TGFß1, paradoxical growth is seen in experimental models of gastric and small intestinal (SI) NENs. Therapeutic targeting of TGFß1 in NENs is therefore complicated by uncertainty of the effect of TGFß1 secretion on the direction of proliferative regulation. CTGF expression is associated with more malignant clinical phenotypes in a variety of cancers, including NENs. CTGF promotes growth in gastric and SI-NEN models, and is implicated as a mediator of local and distant fibrosis caused by NENs of enterochromaffin cell origin. CTGF inhibitors are available, but their anti-proliferative effect has not been tested in NENs. In summary, growth factors are essential for NEN proliferation, and although interventions targeting these proteins are effective in experimental models, only limited clinical efficacy has been identified.

Protective effect of a caspase inhibitor in models for cerebral ischemia in vitro and in vivo.

In primary neuronal-astrocyte cultures from mouse brain, ischemic conditions were simulated by combined oxygen-glucose deprival (OGD) for 2 hrs. This treatment resulted in near complete neuronal damage 24 hrs. later and was accompanied by DNA degradation and apoptotic nuclear morphology. Since caspases are key enzymes in the propagation and execution of programmed cell death, we evaluated the effect of the caspase inhibitor z-VAD-fmk. Damage following 2 hrs. OGD could be reduced by up to 56% with z-VAD-fmk (p<0.05). DNA-fragmentation and caspase activation has been also reported in an in vivo model of cerebral ischemia imitating human stroke. In this model the middle cerebral artery (MCA) is permanently occluded resulting in focal cerebral ischemia and subsequent infarction. Since z-VAD.fmk does not penetrate the blood-brain barrier it was applied intraventricularly as a bolus injection given 30 min. before MCA occlusion which was followed by 24 hrs. of infusion. Infarct volume was determined 48 hrs. after MCA occlusion by means of in vivo magnetic resonance imaging. Z-VAD.fmk dose dependently reduced infarct volume reaching a significant decrease of the cortical infarct by 45% when given as a 120 ng bolus followed by 40 ng/hr. infusion (p<0.05). In summary, our study supports the concept that caspase inhibitors are beneficial in brain ischemia.

[Diagnosis of extrauterine pregnancy]. / Diagnosi della gravidanza extrauterina.

In pregnancies, the incidence of ectopic pregnancy varies from 1.2% to 1.4%. Diagnostic management of ectopic pregnancy is made by biochemical and ultrasonographic analysis. The evaluation of symptoms and anamnesis improves both comprehension and evaluation of technical data. This review analyzed the risk factors most commonly reported in women with ectopic pregnancy. According to the literature, the improvement of biochemical knowledge has determined the study of many substances: beta hCG, specific glycoproteins beta 1, creatine kinase, renine, progesterone. Transvaginal ultrasound examination presents different specificity and sensitivity. When ultrasonic imagining is not clear, it is useful to study uterine and adnexal vascularization by color Doppler and pulsed Doppler. The majority of authors consider laparoscopy as a gold standard for diagnosing an ectopic pregnancy. The endoscopic approach has multiple advantages: it could be in the same time diagnostic and therapeutic. The curettage of uterine cavity has been proposed as a diagnostic tool for analyzing by frozen section the presence or not of chorial villi. In personal opinion, an easy and simple diagnostic management should involve the clinical, biochemical and ultrasonographic procedures. Laparoscopy should be the last step in order to confirm a diagnosis and to establish the best therapeutical approach.

Cloning and expression of the cDNA coding for a human lymphocyte IgE receptor.

Low-affinity receptors (Fc epsilon R) and secreted factors (IgE-BF) which bind to immunoglobulins of the IgE isotype play a key role in the regulation of human IgE synthesis. We report here the cloning of a cDNA coding for the Fc epsilon R of the human B-lymphoblast cell line RPMI 8866. The nucleotide sequence of this cDNA predicts a polypeptide with 321 amino acids and a mol. wt of 36,281 daltons. A functional Fc epsilon R capable of binding IgE was expressed in Chinese hamster ovary cells after stable transformation with the cDNA which had been cloned into a mammalian expression vector. Amino acid sequence analysis of IgE-BF purified from RPMI 8866 cells revealed an amino-terminal sequence of 19 residues which coincides with the predicted amino acid sequence of the Fc epsilon R, starting at residues 148 and 150. A computer search with the translated amino acid sequence of the Fc epsilon R revealed a domain of 120 amino acids having striking homology to the human asialoglycoprotein receptors.

Microtubule-associated protein 2 and tubulin are differently distributed in the dendrites of developing neurons.

We have followed the appearance of two microtubule proteins, tubulin and microtubule-associated protein 2, in rat hippocampal neurons differentiating in cell culture. Double-label immunofluorescence staining showed that from day 1 in vitro onward tubulin appeared as filaments but that microtubule-associated protein 2 remained distributed throughout the cytoplasm. This difference persisted throughout development and was also detectable in cells that had reached morphological maturity. When cells were treated with the microtubule-depolymerizing agent nocodazole, the depolymerized tubulin became spread throughout the cytoplasm so that its distribution was then identical to microtubule associated protein 2. At the same time, multiple side branches began to emerge along the dendrites. When cells which had been exposed to nocodazole were allowed to recover before staining, the tubulin was again present as filaments but the microtubule-associated protein 2 remained distributed throughout the dendritic cytoplasm. Under these conditions the previously extended proximal side branches were resorbed into the main process. These results suggest that cellular microtubule-associated protein 2 is not necessarily exclusively associated with microtubules. Neuronal dendrites in particular appear to contain this protein at levels in excess of the capacity of microtubular microtubule-associated protein 2 binding sites. In view of the known effectiveness of microtubule-associated protein 2 as a promoter of tubulin polymerization, its abundance in dendrites suggests that it acts to ensure total polymerization of dendritic microtubules. In this way it would contribute both to the support of the growing process and the suppression of adventitious sidebranching.