A linear approach for sparse coding by a two-layer neural network

Many approaches to transform classification problems from non-linear to linear by feature transformation have been recently presented in the literature. These notably include sparse coding methods and deep neural networks. However, many of these approaches require the repeated application of a learning process upon the presentation of unseen data input vectors, or else involve the use of large numbers of parameters and hyper-parameters, which must be chosen through cross-validation, thus increasing running time dramatically. In this paper, we propose and experimentally investigate a new approach for the purpose of overcoming limitations of both kinds. The proposed approach makes use of a linear auto-associative network (called SCNN) with just one hidden layer. The combination of this architecture with a specific error function to be minimized enables one to learn a linear encoder computing a sparse code which turns out to be as similar as possible to the sparse coding that one obtains by re-training the neural network. Importantly, the linearity of SCNN and the choice of the error function allow one to achieve reduced running time in the learning phase. The proposed architecture is evaluated on the basis of two standard machine learning tasks. Its performances are compared with those of recently proposed non-linear auto-associative neural networks. The overall results suggest that linear encoders can be profitably used to obtain sparse data representations in the context of machine learning problems, provided that an appropriate error function is used during the learning phase

Neural Networks with Non-Uniform Embedding and Explicit Validation Phase to Assess Granger Causality

A challenging problem when studying a dynamical system is to find the interdependencies among its individual components. Several algorithms have been proposed to detect directed dynamical influences between time series. Two of the most used approaches are a model-free one (transfer entropy) and a model-based one (Granger causality). Several pitfalls are related to the presence or absence of assumptions in modeling the relevant features of the data. We tried to overcome those pitfalls using a neural network approach in which a model is built without any a priori assumptions. In this sense this method can be seen as a bridge between model-free and model-based approaches. The experiments performed will show that the method presented in this work can detect the correct dynamical information flows occurring in a system of time series. Additionally we adopt a non-uniform embedding framework according to which only the past states that actually help the prediction are entered into the model, improving the prediction and avoiding the risk of overfitting. This method also leads to a further improvement with respect to traditional Granger causality approaches when redundant variables (i.e. variables sharing the same information about the future of the system) are involved. Neural networks are also able to recognize dynamics in data sets completely different from the ones used during the training phase

Immunohistochemical expression and distribution of orexin, orphanin and leptin in the major salivary glands of some mammals

Abstract: The aim of the study was to assess the involvement of apoptotic factors, cytokeratins and metalloproteinase- 9 in the histogenesis of both Epithelialized Gingival Lesions (EGL) and Periapical Lesions (PAL). 55 consecutive patients, 30 with PAL and 25 with EGL, were selected for the study after clinical and radiological examinations. The PAL patients had severe periapical lesions and tooth decay with exposure of the pulp chamber. All PAL and EGL biopsies were surgically extracted, fixed in 10% buffered formalin, and processed for routine light microscopy. Ten biopsies of each category were processed for immunohistochemistry (IHC). Serial paraffin sections were stained by IHC with appropriate antibodies to detect cytokeratins (CKs) 1, 5, 8, 10 and 14, caspase-3 and -9, metalloproteinase-9, and for PCNA and TUNEL assays. Both PAL and EGL showed a high expression of the cytokeratin 1, 5 and 8 with higher expression in EGL. Moreover, CK10 was markedly less intense expressed in EGL compared to PAL, while CK14 was almost three times stronger expressed in EGL. The expression of caspase-3 and -9 was stronger in PAL compared to EGL, however, the difference was only significant for caspase-9. In PAL apoptosis detected by TUNNEL method and the expression of MMP-9 were higher than in EGL, whereas PCNA was significantly more expressed in EGL. The results clearly suggest that both lesions have exclusively an epithelial origin and that epithelial proliferation was correlated with the degree of apoptosis in both entities. PAL and EGL presented mostly similar cytokeratin expression except for CK10 and CK14, though with marked differences in the distribution and intensity of IHC reactions. Finally, the degradation of extracellular matrix in both lesions could be partially attributed to the strong presence of MMP-9. (Folia Histochemica et Cytobiologica 2012, Vol. 50, No. 4, 497–503)The aim of the study was to determine by immunochemistry the expression of leptin, orexin A and orphanin FQ in the major salivary glands (parotid, submandibular and sublingual) of rat, sheep and cow. These peptides, originally synthesized in central nervous system, adipose tissue and peripheral tissues including gastrointestinal tract, play an orexigenic (orphanin and orexin) or anorexigenic (leptin) roles in the intricate neuronal network appointed to the control of nutritional homeostasis. Peptide-specific immunoreactivity was present in the studied salivary glands with various intensities in different species, in the ductal epithelium, sometimes in the acinar epithelium, and in nervous trunks spread in connective tissue stroma. The obtained data show that salivary glands present an unexpected source of orexigenic and anorexigenic peptides which with their autocrine, paracrine, and endocrine mechanisms of action may participate in the control of salivary gland function

Non-motor impairments affect walking kinematics in Parkinson disease patients: A cross-sectional study

Background: In patients with Parkinson disease (PD), severe postural and gait impairments are rarely observed in early stage of disease and non-motor symptoms (NMS) are often overlooked. Objective: This observational study aimed to characterize the impact of non-motor impairments on walking kinematics in early stages PD patients, and to assess the differences of gait parameters and NMS between PD patients with and without mild cognitive impairment (MCI). Methods: Twenty-six patients with Modified Hoehn and Yahr Scale score≤2 were evaluated for NMS using Kings Parkinson's Pain Scale, Parkinson Fatigue Severity scale, Parkinson Anxiety Scale, Beck Depression Inventory and Epworth Sleepiness Scale, kinematic parameters through an inertial sensor and cognitive performance by a comprehensive neuropsychological battery. Results: Fatigue had a moderate negative correlation with step cadence, and a moderate to strong positive correlation with gait duration, Timed Up and Go (TUG) and TUG Dual Task (p < 0.01). Pain showed positive moderate correlation with gait duration (p < 0.01). Twelve patients resulted affected by MCI and reported significantly worse scores in gait duration, pain and fatigue (p < 0.05). According to cognitive z scores, PD-MCI group showed a moderate negative correlation between visuospatial abilities and fatigue (p < 0.05). Conclusions: NMS significantly affect walking kinematics whereas a limited role of cognitive status on motor performance occur in the early PD stages

Rare histotypes of epithelial biliary tract tumors: A literature review

Adenocarcinoma represents the most frequent biliary tract cancer. However, other rare histotypes can be found in the biliary tract, such as cholangiolocellular carcinoma, cholangiocarcinoma with ductal plate malformation pattern, adenosquamous carcinoma, mucinous carcinoma, signet ring cell carcinoma, clear cell carcinoma, mucoepidermoid carcinoma, lymphoepithelioma-like carcinoma, and sarcomatous cholangiocarcinoma. These cancer types account for less than 10 % of all the already rare biliary tract tumors. Yet, they represent a relevant issue in everyday clinical practice, given the lack of therapeutic recommendations and the overall scarcity of data, mainly deriving from isolated small center-specific cohorts of patients.The shifts of such histotypes from the most common ones reflect genetic and molecular differences, determine changes in clinical aggressiveness, and suggest a possible variability in sensitivity to the standard treatments of biliary adenocarcinomas. The consistency and degree of these variables are still to be solidly demonstrated and investigated. Therefore, this paper aims to review the current literature concerning very infrequent and rare epithelial biliary tract cancers, focusing our attention on the clinical, molecular, and immunohistochemical features of these tumors

Effects of dietary protein and phosphorus restriction on the progression of early renal failure

Effects of dietary protein and phosphorus restriction on the progression of early renal failure. Three groups of patients with chronic renal failure were studied. Group 1 comprised 25 patients with a mean serum creatinine of 2.18mg/dl and a mean arterial pressure of 117mm Hg. Group 2 had 20 patients with a mean serum creatinine of 4.24mg/dl and a mean arterial pressure of 119mm Hg. All these patients were kept for 18 to 76 months on a diet containing about 40 kcal/kg, 0.6 g/kg of protein, 700mg of phosphorus, and 1,000 to 1,500mg of calcium (orally supplemented). Group 3 comprised 30 patients with a mean serum creatinine of 2.28mg/dl and a mean arterial pressure of 116mm Hg. They had followed no specific dietary regimen for 3 to 72 months, and their dietary calorie, protein, phosphorus, and calcium intakes averaged 35 kcal/kg, 70 g, 900mg, and 800mg, respectively. The plots of reciprocal creatinine against time gave slopes of -0.0008 and -0.0010 in patients in groups 1 and 2, and a slope of -0.020 in group 3 patients. The slopes of both groups 1 and 2 were statistically different (analysis of variance and “F” test, P < 0.01) from that of group 3. No evidence of progressive protein and phosphorus depletion was observed in groups 1 and 2 patients. We conclude that a moderate dietary restriction of protein and phosphorus is an acceptable and effective regimen for delaying progression of functional deterioration in early renal failure.Effet de la restriction protéique et phosphorée alimentaire sur la progression de l'insuffisance rénale débutante. Trois groupes de malades ayant une insuffisance rénale chronique ont été étudiés. Le groupe 1 comprenait 25 malades ayant une créatinine sérique moyenne de 2,18mg/dl et une pression artérielle moyenne de 117mm Hg. Le groupe 2 comportait 20 malades ayant une créatinine sérique moyenne de 4,24mg/dl et une pression artérielle moyenne de 119mm Hg. Tous ces malades ont été soumis pendant 18 à 76 mois à un régime contenant environ 40 kcal/kg, 0,6kg de protéines, 700mg de phosphore, et 1000 à 1500mg de calcium (par supplémentation orale). Le groupe 3 comprenait 30 malades ayant une créatinine sérique moyenne de 2,28mg/dl et une pression artérielle moyenne de 116mm Hg. Ils n'avaient pas suivi de régime alimentaire spécifique pendant 3 à 72 mois, et leurs apports alimentaires caloriques, protéiques, phosphorés et calciques étaient en moyenne de 35 kcal/kg, 70 g, 900mg, et 800mg, respectivement. Les courbes de créatinine en fonction du temps ont donné des pentes de -0,0008 et de -0,0010 chez les malades des groupes 1 et 2, et une pente de -0,020 chez ceux de groupe 3. Des pentes des groupes 1 et 2 différaient statistiquement (analyse de variance et test de “F”, P < 0,01) de ceux du groupe 3. Il n'a pas été observé de preuve de déplétion progressive en protéines et en phosphore chez les malades des groupes 1 et 2. Nous concluons qu'une restriction alimentaire modérée en protéines et en phosphore est un régime acceptable et efficace pour retarder la progression de la détérioration fonctionnelle au cours de l'insuffisance rénale précoce

Long QT syndrome and left ventricular non-compaction in a family with KCNH2 mutation: A case report

Background: Left ventricular non-compaction (LVNC) is an abnormality of the myocardium, characterized by prominent left ventricular trabeculae and deep inter-trabecular recesses. Long QT syndrome (LQTS) is a cardiac ion channelopathy presenting with a prolonged QT interval on resting electrocardiogram and is associated with increased susceptibility to sudden death. The association between LVNC and LQTS is uncommon. Case presentation: We report an Italian family with a novel pathogenic KCNH2 variant who presented with clinical features of LVNC and LQTS. The proband came to our attention after two syncopal episodes without prodromal symptoms. His ECG showed QTc prolongation and deep T wave inversion in anterior leads, and the echocardiogram fulfilled LVNC criteria. After that, also his sister was found to have LQTS and LVNC, while his father only presented LQTS. Conclusions: Physicians should be aware of the possible association between LVNC and LQTS. Even if this association is rare, patients with LVNC should be investigated

Influence of age and gender variations on glomerular filtration rate estimated by the MCQE formula

Uvod: U kliničkoj se praksi stopa glomerularne filtracije (enq. glomerularfil-tration rate, GFR) rutinski određuje jednadžbom temeljenoj na koncentraciji kreatinina u serumu, razvijenoj i potvrđenoj u okviru studije MDRD (engl. Modification of Dietin Renal Disease Study, MDRD). Međutim, budući da jednadžba podcjenjuje smanjenje GFR, razvijena je jednadžba MCQE (engl. Mayo Clinic Quadratic Equation, MCQE). Ispitanici i metode: Svrha ovoga istraživanja bila je analizirati utjecaj varijacije dobi i spola kod određivanja GFR pomoću jednadžbe MCQE. Iz baze podataka našega laboratorijskog informatičkog sustava uzeti su rezultati 16.631 određivanja koncentracije kreatinina u serumu provedenih na uzastopnim ispitanicima. Rezultati: Razlika u određivanju GFR između muškaraca i žena bila je statistički značajna kod računanja objema jednadžbama (MDRD i MCQE). Statistički značajne razlike zabilježene su kod svih dobnih skupina u razredima od po deset godina kod računanja jednadžbom MCQE, a kod računanja jednadžbom MDRD samo kod ispitanika starijih od 51 godine. Zabilježena je i statistički značajna razlika u srednjoj vrijednosti GFR određenoj objema jednadžbama između različ itih dobnih skupina u razredima od po deset godina kod oba spola. Zaključak: Rezultati ove epidemiološke analize potvrđuju da se niti jednadžbom MCQE ne mogu nadomjestiti varijacije dobi i spola.Background: In clinical practice, the glomerular filtration rate (GFR) is routinely estimated by the creatinine-based equation developed and validated from the Modification of Diet in Renal Disease (MDRD) Study. However, since this formula estimates the rate of decline in GFR, the Mayo Clinic Quadratic Equation (MCQE) has been developed. Petients and methods: The purpose of this study was to assess the influence of age and gender variations on GFR estimated by this new equation. Results of 16,631 serum creatinine tests performed in consecutive outpatients were retrieved from the database of our Laboratory Information System. GFR was estimated by both the MDRD and MCQE formulas. Results: The difference in the estimated GFR between males and females was significantly different when calculated with either MDRD or MCQE formula. Significant gender differences were observed in all age decades by MCQE and in subjects aged >51 years by MDRD. A significant difference in the mean GFR values estimated by either formula was also observed between different age decades in both genders. Conclusions: The results of this epidemiological analysis indicated the MCQE formula also fail to compensate for age and gender variations

Changes in Corticospinal Circuits During Premovement Facilitation in Physiological Conditions.

Changes in corticospinal excitability have been well documented in the preparatory period before movement, however, their mechanisms and physiological role have not been entirely elucidated. We aimed to investigate the functional changes of excitatory corticospinal circuits during a reaction time (RT) motor task (thumb abduction) in healthy subjects (HS). 26 HS received single pulse transcranial magnetic stimulation (TMS) over the primary motor cortex (M1). After a visual go signal, we calculated RT and delivered TMS at three intervals (50, 100, and 150 ms) within RT and before movement onset, recording motor evoked potentials (MEP) from the abductor pollicis brevis (APB) and the task-irrelevant abductor digiti minimi (ADM). We found that TMS increased MEPAPB amplitude when delivered at 150, 100, and 50 ms before movement onset, demonstrating the occurrence of premovement facilitation (PMF). MEP increase was greater at the shorter interval (MEP50) and restricted to APB (no significant effects were detected recording from ADM). We also reported time-dependent changes of the RT and a TMS side-dependent effect on MEP amplitude (greater on the dominant side). In conclusion, we here report changes of RT and side-dependent, selective and facilitatory effects on the MEPAPB amplitude when TMS is delivered before movement onset (PMF), supporting the role of excitatory corticospinal mechanisms at the basis of the selective PMF of the target muscle during the RT protocol