Deficits in category learning in older adults: rule-based versus clustering accounts

Memory research has long been one of the key areas of investigation for cognitive aging researchers but only in the last decade or so has categorization been used to understand age differences in cognition. Categorization tasks focus more heavily on the grouping and organization of items in memory, and often on the process of learning relationships through trial and error. Categorization studies allow researchers to more accurately characterize age differences in cognition: whether older adults show declines in the way in which they represent categories with simple rules or declines in representing categories by similarity to past examples. In the current study, young and older adults participated in a set of classic category learning problems, which allowed us to distinguish between three hypotheses: (i) rule-complexity: categories were represented exclusively with rules and older adults had differential difficulty when more complex rules were required, (ii) rule-specific: categories could be represented either by rules or by similarity, and there were age deficits in using rules, and (iii) clustering: similarity was mainly used and older adults constructed a less-detailed representation by lumping more items into fewer clusters. The ordinal levels of performance across different conditions argued against rule-complexity, as older adults showed greater deficits on less complex categories. The data also provided evidence against rule-specificity, as single-dimensional rules could not explain age declines. Instead, computational modelling of the data indicated that older adults utilized fewer conceptual clusters of items in memory than did young adults

Minimizing the postoperative complications of severe hypospadias using a simple technique

Background The aim of this study was to decrease complication rates in proximal hypospadias surgery.Methods A simple method of stenting using a polypropylene stent has been developed for the most severe form of hypospadias during the period from January 2008 to January 2011 in the Department of Pediatric Surgery. The total number of patients was 46. The patients were classified into group 1 (n= 23), in which a polypropylene stent was used, and group 2 (n= 23), in which a polypropylene stent was not used.Results In group 1, complications occurred in three patients (13.04%), whereas in group 2 it occurred in 12 patients (52.2%). The difference in the total number of complications between groups was highly significant (P < 0.001). In group 1, no patient needed redo surgery, and in group 2 four patients (17.39%) needed redo surgery (P < 0.05). All other patients responded to repeated dilatation in the follow-up.Conclusion Although the sample size was small, this simple modification can decrease the complication rate significantly in the most severe form of hypospadias. Keywords: polypropylene stent, proximal hypospadias, surgical complications, urethroplast

Jejunal atresia presenting with mesenteric cyst in a neonate: a case report

Jejunoileal atresia is a congenital anomaly that is characterized clinically by bilious vomiting and abdominal distension. It has been associated with various congenital anomalies but its association with mesenteric cyst has only been reported sporadically. As this is a very rare entity, it is being reported with a brief review of literature

ATM, ATR, and DNA-PK: The Trinity at the Heart of the DNA Damage Response

In vertebrate cells, the DNA damage response is controlled by three related kinases: ATM, ATR, and DNA-PK. It has been 20 years since the cloning of ATR, the last of the three to be identified. During this time, our understanding of how these kinases regulate DNA repair and associated events has grown profoundly, although major questions remain unanswered. Here, we provide a historical perspective of their discovery and discuss their established functions in sensing and responding to genotoxic stress. We also highlight what is known regarding their structural similarities and common mechanisms of regulation, as well as emerging non-canonical roles and how our knowledge of ATM, ATR, and DNA-PK is being translated to benefit human health

Read-Across for Rat Oral Gavage Repeated-Dose Toxicity for Short-Chain Mono-Alkylphenols: A Case Study

Short-chain mono-alkylphenols provide an example of where a category-approach to read-across may be used to estimate the repeated-dose endpoint for a number of derivatives. Specifically, the NOAELs of 50 mg/kg bw/d for mono-methylphenols based on a LOAEL of very low systemic toxicity can be read across with confidence to untested mono-alkylphenols in the category. These simple alkylphenols are non-reactive and exhibit an unspecific, reversible polar narcosis mode of toxic action. Briefly, polar narcotics act via unspecific, reversible interactions with biological membranes in a manner similar to cataleptic anaesthetics. The read-across premise includes rapid and complete absorption via the gastrointestinal tract, distribution in the circulatory system, first-pass Phase 2 metabolism in the liver, and elimination of sulphates and glucuronides in the urine. Thus, toxicokinetic parameters are considered to be similar and have the same toxicological significance. Five analogues have high quality experimental oral repeated-dose toxicity data (i.e., OECD TG 408 or OECD TG 422). These repeated-dose toxicity test results exhibit qualitative consistency in symptoms. Typical findings include decreased body weight and slightly increased liver and kidney weights which are generally without concurrent histopathological effects. The sub-chronic findings are quantitatively consistent with the No Observed Adverse Effect Level (NOAEL) of ≥ 50 mg/kg bw/d. Chemical similarity between the analogues is readily defined, and data uncertainty associated with the similarities in toxicokinetic properties, as well as toxicodynamic properties, are low. Uncertainty associated with mechanistic relevance and completeness of the read-across is low-to-moderate, largely because there is no adverse outcome pathway or intermediate event data. Uncertainty associated with mechanistic relevance and completeness of the read-across is reduced by the concordance of in vivo, in vitro, USEPA toxicity forecaster (ToxCast) results, as well as the in silico data. The rat oral repeated-dose NOAEL values for the source substances can be read across to fill the data gaps of the untested analogues in this category with uncertainty deemed equivalent to results from a TG 408 assessment

Synovial cell metabolism and chronic inflammation in rheumatoid arthritis

Metabolomic studies of body fluids show that immune-mediated inflammatory diseases such as rheumatoid arthritis (RA) are associated with metabolic disruption. This is likely to reflect the increased bioenergetic and biosynthetic demands of sustained inflammation and changes to nutrient and oxygen availability in damaged tissue. The synovial membrane lining layer is the principle site of inflammation in RA. Here the resident cells are the fibroblast-like synoviocytes (FLS) and the synovial tissue macrophages (STM), which are transformed toward overproduction of enzymes which degrade cartilage and bone, and cytokines which promote immune cell infiltration. Recent studies have shown metabolic changes in both FLS and macrophages from RA patients and these may be therapeutically targetable. However, as the origins and subset specific functions of synoviocytes are poorly understood and the signaling modules which control metabolic deviation in RA synovial cells are yet to be explored, significant additional research is needed to translate these findings toward clinical application. Furthermore, in many inflamed tissues, different cell types can forge metabolic collaborations through solute carriers (SLC) in their membranes, to meet a high demand for energy or biomolecules. Such relationships are likely to exist in the synovium and are yet to be explored. Finally, it is not yet known whether metabolic change is a consequence of disease or if primary changes to cellular metabolism might underlie or contribute to early stage disease pathogenesis. This article collates what is known about metabolism in synovial tissue cells and highlights future research directions in this area

Pediatric carcinoma of rectum - Varanasi experience

Background : Primary gastrointestinal system malignancies constitute approximately 2% of pediatric neoplasm and of these; colorectal carcinoma is the second most common malignancy. This is one of the rarer diseases in children. Aim : We reviewed our records to study the clinical features, outcome and the follow-up of this condition with evaluation of the prognostic factors. Settings and Design: Tertiary care Pediatric Surgery centre. Retrospective study. Materials and Methods : The data of all patients with diagnosis of colorectal carcinoma from January 1986 to January 2006 were reviewed. The confirmation of the diagnosis was by biopsy from the lesion. The age, sex, family history, clinical features, response to the treatment and follow-up were studied. Results : There were four male patients. All had bleeding per rectum as the presenting complaint. Three patients had advanced disease at presentation. All the patients had signet cell adenocarcinoma. The two patients expired and one was lost to follow-up. One patient is alive after one year of follow up and is receiving treatment. Conclusion : Colorectal cancer in children though rare can be a reality, hence any children presenting with pain in abdomen along with doubtful history of constipation and rectal bleeding should be examined carefully with special emphasis on digital rectal examination

Atomic-scale combination of germanium-zinc nanofibers for structural and electrochemical evolution

Alloys are recently receiving considerable attention in the community of rechargeable batteries as possible alternatives to carbonaceous negative electrodes; however, challenges remain for the practical utilization of these materials. Herein, we report the synthesis of germanium-zinc alloy nanofibers through electrospinning and a subsequent calcination step. Evidenced by in situ transmission electron microscopy and electrochemical impedance spectroscopy characterizations, this one-dimensional design possesses unique structures. Both germanium and zinc atoms are homogenously distributed allowing for outstanding electronic conductivity and high available capacity for lithium storage. The as-prepared materials present high rate capability (capacity of similar to 50% at 20 C compared to that at 0.2 C-rate) and cycle retention (73% at 3.0 C-rate) with a retaining capacity of 546 mAh g(-1) even after 1000 cycles. When assembled in a full cell, high energy density can be maintained during 400 cycles, which indicates that the current material has the potential to be used in a large-scale energy storage system

Double coin in esophagus at same location and same alignment - a rare occurrence: a case report

Coin is the most common foreign body swallowed by pediatric age group. The multiple coin swallowing is extremely rare and very few cases had been reported in English literature. Most of them were present at different site and had different alignment in the esophagus. The location of the coin (trachea vs. esophagus) is commonly determined by the alignment of the coin on radiographic studies. A 4-year-girl was presented to us with history of coin ingestions one day back without any respiratory distress. On radiological study there was suspicion of two coins on same location and alignment. The diagnosis was confirmed after removal. The both coin was removed successfully by esophagoscopy. Unexpected second foreign bodies in pediatric esophageal coin ingestions are rare and it is mandatory to do post operative radiography after removal to exclude duplex coin or tracheal coin. We are presenting this case because of its rarity, difficulty in diagnosis especially when proper history is not available

Elucidating the Limit of Li Insertion into the Spinel Li4Ti5O12

In this work, we show that the well-known lithium-ion anode material, Li4Ti5O12, exhibits exceptionally high initial capacity of 310 mAh g-1 when it is discharged to 0.01 V. It maintains a reversible capacity of 230 mAh g-1, far exceeding the "theoretical" capacity of 175 mAh g-1 when this anode is lithiated to the composition Li7Ti5O12. Neutron diffraction analyses identify that additional Li reversibly enters into the Li7Ti5O12 to form Li8Ti5O12. density functional theory (DFT) calculations reveal the average potentials of the Li4Ti5O12 to Li7Ti5O12 step and the Li7Ti5O12 to Li8Ti5O12 step are 1.57 and 0.19 V, respectively, which are in excellent agreement with experimental results. Transmission electron microscopy (TEM) studies confirm that the irreversible capacity of Li4Ti5O12 during its first cycle originates from the formation of a solid electrolyte interface (SEI) layer. This work clarifies the fundamental lithiation mechanism of the Li4Ti5O12, when lithiated to 0.01 V vs Li