Optimal control strategy of SEIR endemic model with continuous age‐structure in the exposed and infectious classes

In this paper, we consider an endemic Susceptible‐Exposed‐Infectious‐Recovered model with continuous age‐structure for exposed and infectious classes. This work is appropriate for those infectious diseases that have exposed period such as tuberculosis and herpes virus infection. Key result is the existence of an optimal control problem. To control the spread of the disease, we use an objective functional with a suitable control and present an optimal control problem. Finally, we present some simulations that support our theoretical findings and show the effectiveness of the model.     

Hippocampal contributions to recollection in retrograde and anterograde amnesia

Lesions restricted to the hippocampal formation and/or extended hippocampal system (hippocampal formation, fornix, mammillary bodies, and anterior thalamic nuclei) can disrupt conscious recollection in anterograde amnesia, while leaving familiarity-based memory relatively intact. Familiarity may be supported by extra-hippocampal medial temporal lobe (MTL) structures. Within-task dissociations in recognition memory best exemplify this distinction in anterograde amnesia. The authors report for the first time comparable dissociations within recognition memory in retrograde amnesia. An amnesic patient (A.D.) with bilateral fornix and septal nuclei lesions failed to recognize details pertaining to personal past events only when recollection was required, during recognition of episodic details. His intact recognition of generic and semantic details pertaining to the same events was ascribed to intact familiarity processes. Recollective processes in the controls were reflected by asymmetrical Receiver's Operating Characteristic curves, whereas the patient's Receiver's Operating Characteristic was symmetrical, suggesting that his inferior recognition performance on episodic details was reliant on familiarity processes. Anterograde and retrograde memories were equally affected, with no temporal gradient for retrograde memories. By comparison, another amnesic person (K.C.) with extensive MTL damage (involving extra-hippocampal MTL structures in addition to hippocampal and fornix lesions) had very poor recognition and no recollection of either episodic or generic/semantic details. These data suggest that the extended hippocampal system is required to support recollection for both anterograde and retrograde memories, regardless of their age.     

Semantic memory recognition is supported by intrinsic recollection-like processes: “The butcher on the bus” revisited

Dual-process models suggest that recognition memory is independently supported by recollection and familiarity. Current theories attribute recollection solely to hippocampally mediated episodic memory (EM), and familiarity to both episodic and semantic memory (SM) supported by medial temporal lobe cortex (MTLC) and prefrontal cortex. We tested whether, contrary to this view, recollection-like processes also intrinsically support SM recognition and whether MTL structures are involved in their execution. A semantic Process Dissociation Procedure (PDP) with famous and non-famous names was used in three experiments. Experiment 1 revealed that recollection-like processes in semantic memory were not associated with episodic memory for the public events, were predicted by performance on standard SM tasks and were independent of EM tasks, suggesting they are intrinsic to SM. Experiment 2 demonstrated the independence of the two process estimates by showing only familiarity was affected by shifting response criterion while only recollection estimates were significantly altered under divided-attention. Finally experiment 3 tested amnesic patients with varying degrees of hippocampal and MTLC damage. Despite normal overall fame recognition performance, recollection estimates were specifically affected by MTL damage. When damage was primarily hippocampal, only retrograde recollection estimates were reduced, while more extensive MTLC damage led to both retrograde and anterograde recollection deficits. We conclude that recognition of semantic information is supported by at least two independent processes akin to the ones that support EM recognition. Recollection-like processes are intrinsic to SM and likely do not reflect EM contribution to SM performance. Together with previous studies of recollection in remote memory, these data suggest that recollection is not a unitary phenomenon. In EM it involves autonoetic re-experiencing, and is supported by interaction of fronto-temporal networks; in EM and SM it supports retrieval of contextual/associative information regardless of consciousness type, and is dependent on intact MTL function. Familiarity processes and neural substrates may also differ between lifetime familiarity and within-session familiarity.     

Assessment of executive functions in children and adolescents with acquired brain injury (ABI) using a novel complex multi-tasking computerised task: The Jansari assessment of Executive Functions for Children (JEF-C©)

ABSTRACT

Objectives: The Jansari assessment of Executive Functions for Children (JEF-C^©) is a new non-immersive computerised assessment of executive functions. The objectives of the study were to test the feasibility and validity of JEF-C^© in children and adolescents with acquired brain injury (ABI).

Methods: Twenty-nine patients with ABI aged 10–18 years and 30 age-and gender-matched controls were tested. Participants performed JEF-C^©, Wechsler Abbreviated Scale of Intelligence (WASI) and the Behavioural Assessment of the Dysexecutive Syndrome for Children (BADS-C), while parents completed the Behaviour Rating Inventory of Executive Function (BRIEF) questionnaire.

Results: The JEF-C^© task proved feasible in patients with ABI. The internal consistency was medium (Cronbach’s alpha?=?0.62 and significant intercorrelations between individual JEF-C^© constructs). Patients performed significantly worse than controls on most of the JEF-C^© subscales and total score, with 41.4% of participants with ABI classified as having severe executive dysfunction. No significant correlations were found between JEF-C^© total score, the BRIEF indices, and the BADS-C. Significant correlations were found between JEF-C^© and demographic characteristics of the sample and intellectual ability, but not with severity/medical variables.

Conclusion: JEF-C^© is a playful complex task that appears to be a sensitive and ecologically valid assessment tool, especially for relatively high-functioning individuals.     

Is there a relationship between executive functions and academic success in children with neurofibromatosis type 1?

The present study aimed to compare the executive function (EF) of children with neurofibromatosis type 1 (NF1) to those of typically developing children and to investigate whether those abilities could predict the child's academic success in terms of academic skills and enablers. Twenty-nine children with NF1 and 27 age-and-gender-matched controls (aged 8–16 years) were examined with two tests to measure EF in an ecologically valid manner: the Behavioural Assessment of the Dysexecutive Syndrome in Children (BADS-C) and the parent questionnaire for the Behavior Rating Inventory of Executive Function (BRIEF). In order to evaluate academic success we used the Academic Competence Evaluation Scales (ACES). The performance of the NF1 group was significantly lower on the Water and Key search subtest of the BADS-C and on four scales of the BRIEF: initiate; working memory; plan/organise and organisation of materials. Significant correlations and predictive models via regression analysis were generated for: BADS-C, BRIEF and ACES scores. Based on these findings, children with NF1 have executive dysfunction that partially accounts for their difficulties in academic achievements.     

Treatment-refractory schizophrenia

Between one-third and one-half of the individuals who meet diagnostic criteria for schizophrenia remain actively ill despite optimal pharmacological treatment. These individuals tend to progressively deteriorate in terms of social and vocational functioning despite major public and private investments in their rehabilitation. For patients who do not respond to the first prescribed antipsychotic drug, current clinical practice is to switch to a second and a third drug, and eventually to clozapine, the only antipsychotic drug proven to be effective in treatment-refractory schizophrenia (TRS). Occasionally, two antipsychotics are given concomitantly or psychotropic drugs are added to antipsychotic drugs; however, very few empirical data exist to support this practice. Although there are many exceptions, patients who do not benefit from the first prescribed drug will not benefit from any pharmacological intervention. Therefore, efforts are under way to determine the reason for lack of response to available treatments and devise novel, more effective treatments. To be successful these efforts must result in a more specific definition of TRS, as well as in a better understanding of the illness pathophysiology and the mechanism of action of the drugs.     

Effect of a niobium-containing titanium alloy on osteoblast behavior in culture

Background: The chemistry of titanium is a key factor in determining implant–tissue interactions. Reports that a vanadium-based titanium alloy (Ti–6Al–4V) exhibits some cytotoxicity led to a search for an alternative.
Aim: The aim of the present study was to investigate the behavior of human osteoblast-like cells (Saos-2) cultured on Ti–6Al–4V or Ti–6Al–7Nb disks with a rough or a machined surface.
Results: In all four groups, the cells proliferated rapidly between days 1 and 3, and then plateaued. On day 1 of culture, the highest proliferation rate was of cells cultured on disks containing Nb with a machined surface. On day 7, there was no significant difference in cell density on all the tested surfaces. Alkaline phosphatase (ALP) activity was lower on the machined surfaces, regardless of the material used, suggesting that cells on rough surfaces exhibit a more mature phenotype. On day 3, cells cultured on rough disks made of Ti–6Al–7Nb showed the highest ALP activity; the lowest activity was observed on the machined Ti–6Al–4V surface. The highest level of osteocalcin (day 7) was found in the cells cultured on rough Ti–6Al–7Nb disks. Also, higher levels of transforming growth factor (TGFβ) were noted for cells cultured on the rough Ti–6Al–7Nb disks, suggesting that the Nb-containing alloy supports more rapid maturation of the osteoblast.
Conclusions: The results of the present study suggest that according to our cell culture preclinical model, Ti–6Al–7Nb may replace the Ti–6Al–4V alloy as an implant material.     

Pseudo-precocious puberty in a young boy due to interstitial cell adenomas of the testis

A case of pseudo-precocious puberty in a 2 4/12-year-old boy, due to Leydig cell adenomas of the testicle, is described. The special endocrine investigations revealed high levels of plasma testosterone and other androgens together with suppressed plasma gonadotropins unresponsive to stimulation. After operation the hormones returned to normal. The growth velocity and bone age were only gradually decreased, during a period of one year, while the sexual manifestations were the last to disappear, in the third year.