Parvalbumin interneurons constrain the size of the lateral amygdala engram.

Memories are thought to be represented by discrete physiological changes in the brain, collectively referred to as an engram, that allow patterns of activity present during learning to be reactivated in the future. During the formation of a conditioned fear memory, a subset of principal (excitatory) neurons in the lateral amygdala (LA) are allocated to a neuronal ensemble that encodes an association between an initially neutral stimulus and a threatening aversive stimulus. Previous experimental and computational work suggests that this subset consists of only a small proportion of all LA neurons, and that this proportion remains constant across different memories. Here we examine the mechanisms that contribute to the stability of the size of the LA component of an engram supporting a fear memory. Visualizing expression of the activity-dependent gene Arc following memory retrieval to identify neurons allocated to an engram, we first show that the overall size of the LA engram remains constant across conditions of different memory strength. That is, the strength of a memory was not correlated with the number of LA neurons allocated to the engram supporting that memory. We then examine potential mechanisms constraining the size of the LA engram by expressing inhibitory DREADDS (designer receptors exclusively activated by designer drugs) in parvalbumin-positive (PV+) interneurons of the amygdala. We find that silencing PV+ neurons during conditioning increases the size of the engram, especially in the dorsal subnucleus of the LA. These results confirm predictions from modeling studies regarding the role of inhibition in shaping the size of neuronal memory ensembles and provide additional support for the idea that neurons in the LA are sparsely allocated to the engram based on relative neuronal excitability.

Impact of production strategies and animal performance on economic values of dairy sheep traits.

The objective of this study was to carry out a sensitivity analysis on the impact of various production strategies and performance levels on the relative economic values (REVs) of traits in dairy sheep. A bio-economic model implemented in the program package ECOWEIGHT was used to simulate the profit function for a semi-extensive production system with the Slovak multi-purpose breed Improved Valachian and to calculate the REV of 14 production and functional traits. The following production strategies were analysed: differing proportions of milk processed to cheese, customary weaning and early weaning of lambs with immediate sale or sale after artificial rearing, seasonal lambing in winter and aseasonal lambing in autumn. Results of the sensitivity analysis are presented in detail for the four economically most important traits: 150 days milk yield, conception rate of ewes, litter size and ewe productive lifetime. Impacts of the differences in the mean value of each of these four traits on REVs of all other traits were also examined. Simulated changes in the production circumstances had a higher impact on the REV for milk yield than on REVs of the other traits investigated. The proportion of milk processed to cheese, weaning management strategy for lambs and level of milk yield were the main factors influencing the REV of milk yield. The REVs for conception rate of ewes were highly sensitive to the current mean level of the trait. The REV of ewe productive lifetime was most sensitive to variation in ewe conception rate, and the REV of litter size was most affected by weaning strategy for lambs. On the basis of the results of sensitivity analyses, it is recommended that economic values of traits for the overall breeding objective for dairy sheep be calculated as the weighted average of the economic values obtained for the most common production strategies of Slovak dairy sheep farms and that economic values be adjusted after substantial changes in performance levels of the traits.

Ileus, pregnancy or leiomyoma? A case of a large intraabdominal tumor.

OBJECTIVE: Authors evaluate a case of an extremely large leiomyoma, its symptomatology, diagnosis and surgical treatment. They present the possible peroperative complications and emphasize the necessity of the interdisciplinary approach. METHODS: The set of patients consists of 21 patients with leiomyomas of various localizations. All patients were operated by means of conventional operation. The material was sent for classical bioptic examination with the use of immuno-histochemical analysis. RESULTS: Unlike found in literature, the most common appearance of leiomyoma in our set of patients was on small bowel, namely 10 of 21 patients had tumors in this localization. Furthermore there were three tumors of gynecological origin. Two of them had acute abdominal disease (AAD) while in these cases, ileus was a reason for urgent operations. In all three gynecological cases it was difficult to diagnose preoperatively the origin of tumors. In one patient, the preparation led to partial iatrogenic lesion of left ureter which was subsequently treated with primary suture. The authors describe zero mortality. CONCLUSION: Despite the relatively simple diagnosis of leiomyomas, in some cases of extreme size of the tumor combined with its localization in the small pelvis makes it difficult to distinguish it from other mesenchymal tumors. In order eliminate the peroperative complications it is possible to introduce a urethral catheter and to set up a multidisciplinary operation team to achieve combined experience (Fig. 5, Ref. 14).

[Colorectal malignancies with respect to hemocoagulation]. / Malignómy kólonu a rekta z pohl'adu hemokoagulácie.

AIM: Relationship between malignants tumors and damage of hemocoagulation is known. The aim is analyse this damage and evaluate the thrombotic markers. MATERIAL AND METHODICS: Authors analyses group of 137 patients with colorectal malignants tumors. They notifyes to relationship between plasmatic preoperative D dimer, PAI-1, F 1+2, Protein C level with controll group. RESULTS: Especially aggressive forms of colorectal tumours have increased levels of D dimer and PAI-1. Protrombin fragments 1+2 were enhanced in the course of anastomotic dehiscence. Protein C level was reduced in 6.-7. decade and in advanced clinical stage. CONCLUSION: Praeoperative thrombotic markers assays inform about risk of thrombosis and clinical diseases stage. They prefere mini-invasive operations procedures. The maximall validity provides D dimer and PAI-1.

Langerhans' cell histiocytosis in adults.

Three cases of Langerhans' cell histiocytosis with unusual clinical and histopathologic features are described. The first two cases illustrate diagnostic pitfalls that underscore the importance of considering Langerhans' cell histiocytosis in the differential diagnosis of purpuric papular eruptions of the scalp and intertriginous areas, particularly in association with hypothalamic, pituitary, or liver disease. The third case is the first report of Langerhans' cell histiocytosis presenting as a vesicular eruption.