Man against machine: diagnostic performance of a deep learning convolutional neural network for dermoscopic melanoma recognition in comparison to 58 dermatologists

Background

Deep learning convolutional neural networks (CNN) may facilitate melanoma detection, but data comparing a CNN's diagnostic performance to larger groups of dermatologists are lacking.

Methods

Google's Inception v4 CNN architecture was trained and validated using dermoscopic images and corresponding diagnoses. In a comparative cross-sectional reader study a 100-image test-set was used (level-I: dermoscopy only; level-II: dermoscopy plus clinical information and images). Main outcome measures were sensitivity, specificity and area under the curve (AUC) of receiver operating characteristics (ROC) for diagnostic classification (dichotomous) of lesions by the CNN versus an international group of 58 dermatologists during level-I or -II of the reader study. Secondary end points included the dermatologists' diagnostic performance in their management decisions and differences in the diagnostic performance of dermatologists during level-I and -II of the reader study. Additionally, the CNN's performance was compared with the top-five algorithms of the 2016 International Symposium on Biomedical Imaging (ISBI) challenge.

Results

In level-I dermatologists achieved a mean (±standard deviation) sensitivity and specificity for lesion classification of 86.6% (±9.3%) and 71.3% (±11.2%), respectively. More clinical information (level-II) improved the sensitivity to 88.9% (±9.6%, P = 0.19) and specificity to 75.7% (±11.7%, P < 0.05). The CNN ROC curve revealed a higher specificity of 82.5% when compared with dermatologists in level-I (71.3%, P < 0.01) and level-II (75.7%, P < 0.01) at their sensitivities of 86.6% and 88.9%, respectively. The CNN ROC AUC was greater than the mean ROC area of dermatologists (0.86 versus 0.79, P < 0.01). The CNN scored results close to the top three algorithms of the ISBI 2016 challenge.

Conclusions

For the first time we compared a CNN's diagnostic performance with a large international group of 58 dermatologists, including 30 experts. Most dermatologists were outperformed by the CNN. Irrespective of any physicians' experience, they may benefit from assistance by a CNN's image classification.

Clinical trial number

This study was registered at the German Clinical Trial Register (DRKS-Study-ID: DRKS00013570; https://www.drks.de/drks_web/).

The regions of the Fe65 protein homologous to the phosphotyrosine interaction/phosphotyrosine binding domain of Shc bind the intracellular domain of the Alzheimer's amyloid precursor protein

Fe65 is a protein mainly expressed in several districts of the mammalian nervous system. The search of protein sequence data banks revealed that Fe65 contains two phosphotyrosine interaction (PID) or phosphotyrosine binding (PTB) domains, previously identified in the Shc adaptor molecule. The two putative PID/PTB domains of Fe65 were used to construct glutathione S-transferase-Fe65 fusion proteins. Co-precipitation experiments demonstrated that the Fe65 PID/PTB domains interacted with several proteins of apparent molecular mass 135, 115, 105, and 51 kDa. The region of Fe65 containing the PID/PTB domains was used as a bait to screen a human brain cDNA library in yeast by the two-hybrid system. Three different cDNA clones were isolated, two of which contain overlapping segments of the cDNA encoding the COOH terminus of the Alzheimer's beta-amyloid-precursor protein (APP), that represents the short intracellular domain of this membrane protein. The third clone contains a cDNA fragment coding for the COOH terminus of the human counterpart of a mouse beta-amyloid-like precursor protein. The alignment of the three APP encoding cDNA fragments found in the screening suggests that the region of APP involved in the binding is centered on the NPTY sequence, which is analogous to that present in the intracellular domains of the growth factor receptors interacting with the PID/PTB domain of Shc.

The WW domain of neural protein FE65 interacts with proline-rich motifs in Mena, the mammalian homolog of Drosophila enabled

The neural protein FE65 contains two types of protein-protein interaction modules: one WW binding domain and two phosphotyrosine binding domains. The carboxyl-terminal phosphotyrosine binding domain of FE65 interacts in vivo with the beta-amyloid precursor protein, which is implicated in Alzheimer disease. To understand the function of this adapter protein, we identified binding partners for the FE65 WW domain. Proline-rich sequences sharing a proline-proline-leucine-proline core motif were recovered by screening expression libraries for ligands of the FE65 WW domain. Five proteins of molecular masses 60, 75, 80, 140, and 200 kDa could be purified from mouse brain lysates by affinity to the FE65 WW domain. We identified two of these five proteins as the 80- and 140-kDa isoforms encoded by Mena, the mammalian homolog of the Drosophila Enabled gene. Using the SPOTs technique of peptide synthesis, we identified the sequences in Mena that interact with the FE65 WW domain and found that they contain the signature proline-proline-leucine-proline motif. Finally, we demonstrated that Mena binds to FE65 in vivo by coimmunoprecipitation assay from COS cell extracts. The specificity of the Mena-FE65 WW domain association was confirmed by competition assays. Further characterization of the FE65-Mena complex may identify a physiological role for these proteins in beta-amyloid precursor protein biogenesis and may help in understanding the mechanism of molecular changes that underlie Alzheimer disease.

A p53-independent pathway for activation of WAF1/CIP1 expression following oxidative stress

Incubating human cells in diethylmaleate (DEM) depletes the intracellular pool of reduced glutathione (GSH) and increases the concentration of oxidative free radicals. We found that DEM-induced oxidative stress reduced the ability of p53 to bind its consensus recognition sequence and to activate transcription of a p53-specific reporter gene. Nevertheless, DEM treatment induced expression of WAF1/CIP1 but not GADD45 mRNA. The fact that N-acetylcysteine, a precursor of GSH that blocks oxidative stress, prevented WAF1/CIP1 induction by DEM suggests that WAF1/CIP1 induction probably was a consequence of the ability of DEM to reduce intracellular GSH levels. DEM induced WAF1/CIP1 expression in Saos-2 and T98G cells, both of which lack functional p53 protein. DEM treatment did not produce an increase in membrane-associated protein kinase C, but ERK2, a mitogen-activated protein kinase, was phosphorylated in a manner consistent with ERK2 activation. DEM treatment also produced a dose-dependent delay in cell cycle progression, which at low concentrations (0.25 mM) consisted of a G2/M arrest and at higher concentrations (1 mM) also involved G1 and S phase delays. Our results indicate that oxidative stress induces WAF1/CIP1 expression and arrests cell cycle progression through a mechanism that is independent of p53. This mechanism may provide for cell cycle checkpoint control under conditions that inactivate p53.

Functions of WW domains in the nucleus

The WW domain is a protein module found in a wide range of signaling proteins. It is one of the smallest protein modules that folds as a monomer without disulfide bridges or cofactors. WW domains bind proteins containing short linear peptide motifs that are proline-rich or contain at least one proline. Although the WW domain was initially considered a 'cytoplasmic module', the proteins containing WW domains have also been localized in the cell nucleus. Moreover, these proteins have been documented to participate in co-activation of transcription and modulation of RNA polymerase II activity. The carboxy-terminal domain (CTD) of RNA polymerase II acts as an assembly platform for distinct WW domain-containing proteins that affect the function of the RNA polymerase II. The formation of complexes between CTD and WW domain-containing proteins is regulated by phosphorylation of the CTD. Since the CTD sequence is highly repetitive and a target of several post-translational modifications and conformational changes, it presents a unique structure capable of enormous molecular diversity. The WW domain has been implicated in several human diseases including Alzheimer's disease. The WW domain-containing iso-prolyl isomerase named Pin1, a protein known to be essential for cell cycle progression, was shown to be active in restoration of the microtubule-binding activity of Tau, a protein of neurofibrillar tangles found in the brains of Alzheimer's patients. It is the WW domain of Pin1 that interacts directly with Tau protein. In addition, the WW domain-containing adapter protein FE65 was shown to regulate processing of Alzheimer's amyloid precursor protein. It is expected that by understanding the details of the WW domain-mediated protein-protein interactions, we will be able to illuminate numerous signaling pathways which control certain aspects of transcription and cell cycle.

Structured exercise training programme versus hypocaloric hyperproteic diet in obese polycystic ovary syndrome patients with anovulatory infertility: a 24-week pilot study

BACKGROUND

Lifestyle modifications are successfully employed to treat obese and overweight women with polycystic ovary syndrome (PCOS). The aims of the current pilot study were (i) to compare the efficacy on reproductive functions of a structured exercise training (SET) programme with a diet programme in obese PCOS patients and (ii) to study their clinical, hormonal and metabolic effects to elucidate potentially different mechanisms of action.

METHODS

Forty obese PCOS patients with anovulatory infertility underwent a SET programme (SET group, n = 20) and a hypocaloric hyperproteic diet (diet group, n = 20). Clinical, hormonal and metabolic data were assessed at baseline, and at 12- and 24-week follow-ups. Primary endpoint was cumulative pregnancy rate.

RESULTS

The two groups had similar demographic, anthropometric and biochemical parameters. After intervention, a significant improvement in menstrual cycles and fertility was noted in both groups, with no differences between groups. The frequency of menses and the ovulation rate were significantly (P < 0.05) higher in the SET group than in diet group but the increased cumulative pregnancy rate was not significant. Body weight, body mass index, waist circumference, insulin resistance indexes and serum levels of sex hormone-binding globulin, androstenedione and dehydroepiandrosterone sulphate changed significantly (P < 0.05) from baseline and were significantly different (P < 0.05) between the two groups.

CONCLUSIONS

Both SET and diet interventions improve fertility in obese PCOS patients with anovulatory infertility. We hypothesize that in both interventions an improvement in insulin sensitivity is the pivotal factor involved in the restoration of ovarian function but potentially acting through different mechanisms.

Interaction of the phosphotyrosine interaction/phosphotyrosine binding-related domains of Fe65 with wild-type and mutant Alzheimer's beta-amyloid precursor proteins

The two tandem phosphotyrosine interaction/phosphotyrosine binding (PID/PTB) domains of the Fe65 protein interact with the intracellular region of the Alzheimer's beta-amyloid precursor protein (APP). This interaction, previously demonstrated in vitro and in the yeast two hybrid system, also takes place in vivo in mammalian cells, as demonstrated here by anti-Fe65 co-immunoprecipitation experiments. This interaction differs from that occurring between other PID/PTB domain-containing proteins, such as Shc and insulin receptor substrate 1, and activated growth factor receptors as follows: (i) the Fe65-APP interaction is phosphorylation-independent; (ii) the region of the APP intracellular domain involved in the binding is larger than that of the growth factor receptor necessary for the formation of the complex with Shc; and (iii) despite a significant similarity the carboxyl-terminal regions of PID/PTB of Fe65 and of Shc are not functionally interchangeable in terms of binding cognate ligands. A role for Fe65 in the pathogenesis of familial Alzheimer's disease is suggested by the finding that mutant APP, responsible for some cases of familial Alzheimer's disease, shows an altered in vivo interaction with Fe65.

A population-based study of the incidence and prognosis of lacunar stroke

OBJECTIVE

To evaluate incidence and prognosis of lacunar stroke in a prospective, population-based patient registry.

METHODS

The authors included first-ever strokes occurring between 1994 and 1998. They assessed incidence, risk factors, mortality, and recurrence in patients with lacunar stroke.

RESULTS

The authors identified 491 patients (15.3%) with lacunar stroke (252 men and 239 women) and 2,153 patients (67.3%) with nonlacunar stroke (998 men and 1,155 women). Crude annual incidence rate for a first-ever lacunar stroke was 33.0/100,000 (95% CI 30.2 to 36.0). At the univariate logistic regression analysis among patients with lacunar stroke there was a higher proportion of cigarette smoking and hypercholesterolemia and a lower proportion of chronic atrial fibrillation than in patients with nonlacunar stroke. For lacunar stroke, the 30-day case-fatality rate was 4.3% (95% CI 2.5 to 6.1) and the 1-year case-fatality rate was 13.0% (95% CI 10.0 to 16.0). During the first year of follow-up the average annual stroke recurrence rate was lower in patients with lacunar (2.83%; 95% CI 1.36 to 4.30) than in those with nonlacunar stroke (5.10%; 95% CI 4.17 to 6.03) while from the second year onward, rates were similar in both groups.

CONCLUSION

In the short term, patients with nonlacunar stroke had more vascular events, but in the long term, the risk of death and of stroke recurrence was similar.

The DNA-binding efficiency of Sp1 is affected by redox changes

We have previously demonstrated that the DNA-binding efficiency of Sp1 is greatly decreased in nuclear extracts from 30-month-old rat tissues compared to those from young ones, although its gene appears to be normally expressed. As reactive oxygen intermediates are known to accumulate in aged animals, we investigated the effect of oxidation on the Sp1 DNA-binding activity. Electrophoretic mobility shift assays and DNase I footprintings showed that high concentrations of dithiothreitol, added to the aged tissue extracts, fully restore the Sp1 DNA-binding efficiency. However, in young nuclear extracts hydrogen peroxide treatment strongly decreases the Sp1 DNA-binding activity that is restored by the treatment with high dithiothreitol concentrations. To ascertain whether the oxidative stress is directed toward the Sp1 molecule alone, or whether it acts on unknown Sp1 cofactor(s) necessary for DNA binding, we purified Sp1 from young rat liver and demonstrated that when the purified protein is added to aged nuclear extracts, it efficiently binds to its DNA cis-element. Moreover, purified Sp1 treated with hydrogen peroxide lost its ability to bind its cis-element and the DNA-binding efficiency was fully restored after incubation with dithiothreitol.

The Fe65 adaptor protein interacts through its PID1 domain with the transcription factor CP2/LSF/LBP1

The neural protein Fe65 possesses three putative protein-protein interaction domains: one WW domain and two phosphotyrosine interaction/phosphotyrosine binding domains (PID1 and PID2); the most C-terminal of these domains (PID2) interacts in vivo with the Alzheimer's beta-amyloid precursor protein, whereas the WW domain binds to Mena, the mammalian homolog of Drosophila-enabled protein. By the interaction trap procedure, we isolated a cDNA clone encoding a possible ligand of the N-terminal PID/PTB domain of Fe65 (PID1). Sequence analysis of this clone revealed that this ligand corresponded to the previously identified transcription factor CP2/LSF/LBP1. Co-immunoprecipitation experiments demonstrated that the interaction between Fe65 and CP2/LSF/LBP1 also takes place in vivo between the native molecules. The localization of both proteins was studied using fractionated cellular extracts. These experiments demonstrated that the various isoforms of CP2/LSF/LBP1 are differently distributed among subcellular fractions. At least one isoform, derived from alternative splicing (LSF-ID), is present outside the nucleus; Fe65 was found in both fractions. Furthermore, transfection experiments with an HA-tagged CP2/LSF/LBP1 cDNA demonstrated that Fe65 interacts also with the nuclear form of CP2/LSF/LBP1. Considering that the analysis of Fe65 distribution in fractionated cell extracts demonstrated that this protein is present both in nuclear and non-nuclear fractions, we examined the expression of Fe65 deletion mutants in the two fractions. This analysis allowed us to observe that a small region N-terminal to the WW domain is phosphorylated and is necessary for the presence of Fe65 in the nuclear fraction.

Magnetic poly(ε-caprolactone)/iron-doped hydroxyapatite nanocomposite substrates for advanced bone tissue engineering

In biomedicine, magnetic nanoparticles provide some attractive possibilities because they possess peculiar physical properties that permit their use in a wide range of applications. The concept of magnetic guidance basically spans from drug delivery and hyperthermia treatment of tumours, to tissue engineering, such as magneto-mechanical stimulation/activation of cell constructs and mechanosensitive ion channels, magnetic cell-seeding procedures, and controlled cell proliferation and differentiation. Accordingly, the aim of this study was to develop fully biodegradable and magnetic nanocomposite substrates for bone tissue engineering by embedding iron-doped hydroxyapatite (FeHA) nanoparticles in a poly(ε-caprolactone) (PCL) matrix. X-ray diffraction analyses enabled the demonstration that the phase composition and crystallinity of the magnetic FeHA were not affected by the process used to develop the nanocomposite substrates. The mechanical characterization performed through small punch tests has evidenced that inclusion of 10 per cent by weight of FeHA would represent an effective reinforcement. The inclusion of nanoparticles also improves the hydrophilicity of the substrates as evidenced by the lower values of water contact angle in comparison with those of neat PCL. The results from magnetic measurements confirmed the superparamagnetic character of the nanocomposite substrates, indicated by a very low coercive field, a saturation magnetization strictly proportional to the FeHA content and a strong history dependence in temperature sweeps. Regarding the biological performances, confocal laser scanning microscopy and AlamarBlue assay have provided qualitative and quantitative information on human mesenchymal stem cell adhesion and viability/proliferation, respectively, whereas the obtained ALP/DNA values have shown the ability of the nanocomposite substrates to support osteogenic differentiation.

Burden of first-ever ischemic stroke in the oldest old: Evidence from a population-based study

OBJECTIVE

To evaluate the contribution of subjects 80 years old or older to the burden of ischemic stroke as compared with subjects younger than 80 years.

METHODS

All first-ever ischemic strokes occurring in a 5-year period (1994 to 1998) in the population-based L'Aquila registry were traced. Incidence, total health care utilization, disability, and mortality were assessed in patients 80 years old or older, and differences with those younger than 80 years were assessed by univariate and survival analyses.

RESULTS

One thousand three hundred sixteen of 3,594 first-ever ischemic strokes (36.6%) occurred in patients 80 years old or older, accounting on average for one-third of health care utilization. The crude annual incidence rate was 21.54 per 1,000 (95% CI 20.42 to 22.72). At the 1-year follow-up, 27.7% of patients had mild or no disability, 20.7% had severe disability, and 51.6% had died. With respect to patients under 80 years of age, older patients showed a higher proportion of women (61.3 vs 47.7%), atrial fibrillation (30.2 vs 20.7%), coronary heart disease (31.0 vs 23.4%), and peripheral arterial disease (14.6 vs 10.8%) and a lower proportion of cigarette smoking (15.3 vs 29.2%) and hypercholesterolemia (20.4 vs 29.4%). Thirty-day (34.6 vs 13.4%) and 1-year (51.6 vs 22.3%) mortality were higher in patients 80 years old or older than in those younger than 80, mostly in the presence of atrial fibrillation (hazard ratio [HR] was 1.39 for 30-day mortality and 1.37 for 1-year mortality) and diabetes mellitus (HR was 1.39 for 30-day mortality and 1.31 for 1-year mortality).

CONCLUSION

The burden of ischemic stroke is high in subjects 80 years old or older, contributing about one-third of health care utilization and 59.8% of deaths within 30 days.

The beta-amyloid precursor protein functions as a cytosolic anchoring site that prevents Fe65 nuclear translocation

In this study we addressed the question of the intracellular localization of Fe65, an adaptor protein interacting with the beta-amyloid precursor protein (APP) and with the transcription factor CP2/LSF/LBP1. By using tagged Fe65 expression vectors, we observed that a significant fraction of Fe65 is localized in the nucleus of transfected COS7 cells. Furthermore, the isolation of nuclei from untransfected PC12 cells allowed us to observe that a part of the endogenous Fe65 is present in the nuclear extract. The analysis of Fe65 mutant constructs demonstrated that the region of the protein required for its nuclear translocation includes the WW domain, and that, on the other hand, a small fragment of 100 residues, including this WW domain, contains enough structural information to target a reporter protein (green fluorescent protein (GFP)-GFP) to the nucleus. To evaluate whether the Fe65-APP interaction could affect Fe65 intracellular trafficking, COS7 cells were cotransfected with APP(695) or APP(751) and with GFP-Fe65 expression vectors. These experiments demonstrated that Fe65 is no longer translocated to the nucleus when the cells overexpress APP, whereas the nuclear targeting of GFP-Fe65 mutants, unable to interact with APP, is unaffected by the coexpression of APP, thus suggesting that the interaction with APP anchors Fe65 in the cytosol.

Standardization of dermoscopic terminology and basic dermoscopic parameters to evaluate in general dermatology (non-neoplastic dermatoses): an expert consensus on behalf of the International Dermoscopy Society

BACKGROUND

Over the last few years, several articles on dermoscopy of non-neoplastic dermatoses have been published, yet there is poor consistency in the terminology among different studies.

OBJECTIVES

We aimed to standardize the dermoscopic terminology and identify basic parameters to evaluate in non-neoplastic dermatoses through an expert consensus.

METHODS

The modified Delphi method was followed, with two phases: (i) identification of a list of possible items based on a systematic literature review and (ii) selection of parameters by a panel of experts through a three-step iterative procedure (blinded e-mail interaction in rounds 1 and 3 and a face-to-face meeting in round 2). Initial panellists were recruited via e-mail from all over the world based on their expertise on dermoscopy of non-neoplastic dermatoses.

RESULTS

Twenty-four international experts took part in all rounds of the consensus and 13 further international participants were also involved in round 2. Five standardized basic parameters were identified: (i) vessels (including morphology and distribution); (ii) scales (including colour and distribution); (iii) follicular findings; (iv) 'other structures' (including colour and morphology); and (v) 'specific clues'. For each of them, possible variables were selected, with a total of 31 different subitems reaching agreement at the end of the consensus (all of the 29 proposed initially plus two more added in the course of the consensus procedure).

CONCLUSIONS

This expert consensus provides a set of standardized basic dermoscopic parameters to follow when evaluating inflammatory, infiltrative and infectious dermatoses. This tool, if adopted by clinicians and researchers in this field, is likely to enhance the reproducibility and comparability of existing and future research findings and uniformly expand the universal knowledge on dermoscopy in general dermatology. What's already known about this topic? Over the last few years, several papers have been published attempting to describe the dermoscopic features of non-neoplastic dermatoses, yet there is poor consistency in the terminology among different studies. What does this study add? The present expert consensus provides a set of standardized basic dermoscopic parameters to follow when evaluating inflammatory, infiltrative and infectious dermatoses. This consensus should enhance the reproducibility and comparability of existing and future research findings and uniformly expand the universal knowledge on dermoscopy in general dermatology.

The beta-amyloid precursor protein APP is tyrosine-phosphorylated in cells expressing a constitutively active form of the Abl protoncogene

The cytosolic domain of the beta-amyloid precursor protein APP interacts with three PTB (phosphotyrosine binding domain)-containing adaptor proteins, Fe65, X11, and mDab1. Through these adaptors, other molecules can be recruited at the cytodomain of APP; one of them is Mena, that binds to the WW domain (a protein module with two conserved tryptophans) of Fe65. The enabled and disabled genes of Drosophila, homologues of the mammalian Mena and mDab1 genes, respectively, are genetic modulators of the phenotype observed in flies null for the Abl tyrosine kinase gene. The involvement of Mena and mDab1 in the APP-centered protein-protein interaction network suggests the possibility that Abl plays a role in APP biology. We show that Fe65, through its WW domain, binds in vitro and in vivo the active form of Abl. Furthermore, in cells expressing the active form of Abl, APP is tyrosine-phosphorylated. Phosphopeptide analysis and site-directed mutagenesis support the hypothesis that Tyr(682) of APP(695) is the target of this phosphorylation. Co-immunoprecipitation experiments demonstrate that active Abl and tyrosine-phosphorylated APP also form a stable complex, which could result from the interaction of the pYENP motif of the APP cytodomain with the SH2 domain of Abl. These results suggest that Abl, Mena, and mDab1 are involved in a common molecular machinery and that APP can play a role in tyrosine kinase-mediated signaling.

Fe65 and the protein network centered around the cytosolic domain of the Alzheimer's beta-amyloid precursor protein

A distinctive tract of all the forms of Alzheimer's disease is the extracellular deposition of a 40-42/43 amino acid-long peptide derived from the so-called beta-amyloid precursor protein (APP). This is a membrane protein of unknown function, whose short cytosolic domain has been recently demonstrated to interact with several proteins. One of these proteins, named Fe65, has the characteristics of an adaptor protein; in fact, it possesses three protein-protein interaction domains: a WW domain and two PID/PTB domains. The interaction with APP requires the most C-terminal PID/PTB domain, whereas the WW domain is responsible for the interaction with various proteins, one of which was demonstrated to be the mammalian homolog of the Drosophila enabled protein (Mena), which in turn interacts with the cytoskeleton. The second PID/PTB domain of Fe65 binds to the CP2/LSF/LBP1 protein, which is an already known transcription factor. The other proteins interacting with the cytosolic domain of APP are the G(o) heterotrimeric protein, APP-BP1 and X11. The latter interacts with APP through a PID/PTB domain and possesses two other protein-protein interaction domains. The small size of the APP cytodomain and the overlapping of its regions involved in the binding of Fe65 and X11 suggest the existence of competitive mechanisms regulating the binding of the various ligands to this cytosolic domain. In this short review the possible functional roles of this complex protein network and its involvement in the generation of Alzheimer's phenotype are discussed.

Nerve growth factor inhibits apoptosis in memory B lymphocytes via inactivation of p38 MAPK, prevention of Bcl-2 phosphorylation, and cytochrome c release

Survival of memory B lymphocytes is tightly linked to the integrity of the Bcl-2 protein and is regulated by a nerve growth factor (NGF) autocrine circuit. In factor-starved memory B cells, the addition of exogenous NGF promptly induced p38 mitogen-activated protein kinase (MAPK), but not c-Jun N-terminal kinase (JNK), dephosphorylation. Conversely, withdrawal of endogenous NGF was followed by p38 MAPK activation and translocation onto mitochondria, whereby it combined with and phosphorylated Bcl-2, as assessed by co-immunoprecipitation and kinase assays in vivo and in vitro. Mitochondria isolated from human memory B cells, then exposed to recombinant p38 MAPK, released cytochrome c, as did mitochondria from Bcl-2-negative MDCK cells loaded with recombinant Bcl-2. Apoptosis induced by NGF neutralization could be blocked by the specific p38 MAPK inhibitor SB203580 or by Bcl-2 mutations in Ser-87 or Thr-56. These data demonstrate that the molecular mechanisms underlying the survival factor function of NGF critically rely upon the continuous inactivation of p38 MAPK, a Bcl-2-modifying enzyme.

Waterborne outbreak of Norwalk-like virus gastroenteritis at a tourist resort, Italy

In July 2000, an outbreak of gastroenteritis occurred at a tourist resort in the Gulf of Taranto in southern Italy. Illness in 344 people, 69 of whom were staff members, met the case definition. Norwalk-like virus (NLV) was found in 22 of 28 stool specimens tested. The source of illness was likely contaminated drinking water, as environmental inspection identified a breakdown in the resort water system and tap water samples were contaminated with fecal bacteria. Attack rates were increased (51.4%) in staff members involved in water sports. Relative risks were significant only for exposure to beach showers and consuming drinks with ice. Although Italy has no surveillance system for nonbacterial gastroenteritis, no outbreak caused by NLV has been described previously in the country.

Collagen-low molecular weight hyaluronic acid semi-interpenetrating network loaded with gelatin microspheres for cell and growth factor delivery for nucleus pulposus regeneration

Intervertebral disc (IVD) degeneration is one of the main causes of low back pain. Current surgical treatments are complex and generally do not fully restore spine mobility. Development of injectable extracellular matrix-based hydrogels offers an opportunity for minimally invasive treatment of IVD degeneration. Here we analyze a specific formulation of collagen-low molecular weight hyaluronic acid (LMW HA) semi-interpenetrating network (semi-IPN) loaded with gelatin microspheres as a potential material for tissue engineering of the inner part of the IVD, the nucleus pulposus (NP). The material displayed a gel-like behavior, it was easily injectable as demonstrated by suitable tests and did not induce cytotoxicity or inflammation. Importantly, it supported the growth and chondrogenic differentiation potential of mesenchymal stem cells (MSC) and nasal chondrocytes (NC) in vitro and in vivo. These properties of the hydrogel were successfully combined with TGF-β3 delivery by gelatin microspheres, which promoted the chondrogenic phenotype. Altogether, collagen-LMW HA loaded with gelatin microspheres represents a good candidate material for NP tissue engineering as it combines important rheological, functional and biological features.

The first systematic analysis of 3D rapid prototyped poly(ε-caprolactone) scaffolds manufactured through BioCell printing: the effect of pore size and geometry on compressive mechanical behaviour and in vitro hMSC viability

Novel additive manufacturing processes are increasingly recognized as ideal techniques to produce 3D biodegradable structures with optimal pore size and spatial distribution, providing an adequate mechanical support for tissue regeneration while shaping in-growing tissues. With regard to the mechanical and biological performances of 3D scaffolds, pore size and geometry play a crucial role. In this study, a novel integrated automated system for the production and in vitro culture of 3D constructs, known as BioCell Printing, was used only to manufacture poly(ε-caprolactone) scaffolds for tissue engineering; the influence of pore size and shape on their mechanical and biological performances was investigated. Imposing a single lay-down pattern of 0°/90° and varying the filament distance, it was possible to produce scaffolds with square interconnected pores with channel sizes falling in the range of 245-433 µm, porosity 49-57% and a constant road width. Three different lay-down patterns were also adopted (0°/90°, 0°/60/120° and 0°/45°/90°/135°), thus resulting in scaffolds with quadrangular, triangular and complex internal geometries, respectively. Mechanical compression tests revealed a decrease of scaffold stiffness with the increasing porosity and number of deposition angles (from 0°/90° to 0°/45°/90°/135°). Results from biological analysis, carried out using human mesenchymal stem cells, suggest a strong influence of pore size and geometry on cell viability. On the other hand, after 21 days of in vitro static culture, it was not possible to detect any significant variation in terms of cell morphology promoted by scaffold topology. As a first systematic analysis, the obtained results clearly demonstrate the potential of the BioCell Printing process to produce 3D scaffolds with reproducible well organized architectures and tailored mechanical properties.

A rat brain mRNA encoding a transcriptional activator homologous to the DNA binding domain of retroviral integrases

We have isolated a rat cDNA, named FE65, hybridizing to an mRNA of about 2,300 nucleotides present in rat brain, undetectable in rat liver and very poorly represented in other tissues. An mRNA of the same size is present in human neuroblastoma cells and is absent from other human cell lines. The FE65 cDNA contains an open reading frame (ORF) coding for a polypeptide of 499 amino acids in which 143 residues can be aligned with the DNA binding domain of the integrases encoded by mammalian immunodeficiency viruses. The remaining part of the FE65 ORF is not homologous with the correspondent regions of the integrases; the first 206 residues of the FE65 ORF show numerous negative charges and a short sequence not dispensable for the function of the transactivating acidic domain of the jun family transcriptional factors. A plasmid which expresses FE65 amino acids 1-232 fused to the yeast GAL4 DNA binding domain was co-transfected with a plasmid containing five GAL4 binding sites upstream of a minimal Adenovirus promoter controlling the expression of the CAT gene. This experiment showed that the fused protein GAL4-FE65 is able to obtain a 30-40 fold increase of the CAT gene expression compared to the expression observed in the presence of the GAL4 DNA binding domain alone. Two types of FE65 mRNA are present in rat brain, differing only for six nucleotides. We demonstrate that this is the consequence of a neuron-specific alternative splicing of a six-nucleotide miniexon, which is also present in the human genome, in an intron/exon context very similar to that of the rat FE65 gene.

Redox-mediated regulation of p21(waf1/cip1) expression involves a post-transcriptional mechanism and activation of the mitogen-activated protein kinase pathway

p21(waf1/cip1) gene expression is induced by DNA damage in cells with wild-type p53 and contributes to the arrest of cell growth. It was demonstrated that under many experimental conditions, including oxidative stress, p21(waf1/cip1) expression can be induced through p53-independent pathways. Since most of these experimental conditions induce the phosphorylation of mitogen-activated protein kinase (MAPK) and thus its activation, we evaluated p21(waf1/cip1) mRNA levels in cells exposed to an oxidative stress, induced by diethylmaleate (Et2Mal), and in which the MAPK pathway was blocked. The expression of a dominant-negative mutant of MEK, the MAPK kinase that phosphorylates and activates MAPK, and of a dominant-negative [Asn17]Ras mutant prevented the Et2Mal-induced accumulation of p21(waf1/cip1) mRNA. Similarly, the expression of MEK- and of [Asn17]Ras mutants decreased the 12-O-tetradecanoyl-phorbol 13-acetate (TPA)-mediated p21(waf1/cip1) induction. Furthermore, TPA-induced and serum-induced p21(waf1/cip1) mRNA accumulation was blocked by pretreating the cells with the antioxidant compound N-acetylcysteine, suggesting that oxidative stress is involved in these responses. p21(waf1/cip1) mRNA levels reached a maximum within 2 h of adding Et2Mal or TPA; however, the rate of transcription from a p21(waf1/cip1)-promoter construct did not increase during this period. In contrast, cells treated with actinomycin D show an increase of p21(waf1/cip1) mRNA stability after Et2Mal treatment. This result suggests that the increase in p21(waf1/cip1) mRNA at early times results from post-transcriptional regulatory events. Longer exposure to TPA may activate p21(waf1/cip1) gene transcription through an Sp1-dependent mechanism, while Et2Mal treatment gradually inhibits p21(waf1/cip1) gene transcription through oxidative changes that affect Sp1 binding to DNA.