Impaired facial emotion recognition and preserved reactivity to facial expressions in people with severe dementia.

The ability of decoding the emotional facial expressions may be early damaged in frontotemporal dementia, but relatively well preserved in the Alzheimer's disease (AD). Nevertheless, the data about the relationship of the dementia severity with the ability of recognizing the face emotions are conflicting and insufficient, mainly for the moderate-severe stage of the disease. The present study extends to the existing literature by: (1) assessing people in the moderate and severe stage of dementia, compared with people without cognitive impairment; (2) assessing not only recognition but also reactivity to the facial expression of emotion. The capability of understanding the facial emotions has been evaluated in 79 patients with dementia compared to 64 healthy elderly people. The test consisted in showing them 14 photographic representations of 7 emotions both from male and from female faces, representing happiness, sadness, fear, disgust, boredom, anger and surprise. Patients were asked to observe the face and to recognize the emotion either with a denomination or a description. Then the spontaneous reactivity to the face expressions was videotaped and classified as a congruous or incongruous reaction by two independent observers who showed a good inter-rater reliability. Of the patients, 53% with dementia recognized up to 5 emotions out of 14, while in the healthy controls this number of mean recognition raised to 8.4, a value reached by the patients who scored 16 at MMSE. The most identified emotion is happiness both for the patients and for the controls. In general, positive emotions are better recognized than the negative ones, confirming the literary data. About the reactions to face emotion stimuli, there is no significant difference for any of the face emotion between the control group and the people with dementia. These data show that patients with dementia can recognize and react to facial emotions also in the severe stage of the disease, suggesting the usefulness of a non-verbal, emotional communication and supporting the need for more emotional education for care givers, both relatives and professionals.

Ultra rapid calcium events in electrically stimulated frog nerve terminals.

Fast calcium events occurring in cytoplasmic organelles after a single electrical stimulus were investigated by electron spectroscopic imaging (an electron microscope technique that reveals total calcium with high sensitivity and spatial resolution) in quick frozen presynaptic terminals of the frog neuromuscular junction. In resting preparations synaptic vesicles showed a prominent calcium signal whereas mitochondria were mostly negative and only some of the cisternae of the endoplasmic reticulum were clearly positive. In preparations quick frozen 10 ms after the application to the nerve of a single, supramaximal electric stimulus, no obvious change was observed in synaptic vesicles, while calcium levels rose to high values in the endoplasmic reticulum cisternae and in the matrix of mitochondria. Voltage-induced influx of Ca(2+) within synaptic terminals appears therefore to induce an extremely rapid uptake into selected organelles. The possible physiological role of this response is discussed.

The frog neuromuscular junction revisited after quick-freezing-freeze-drying: ultrastructure, immunogold labelling and high resolution calcium mapping.

Until now, most ultrastructural studies on the neuromuscular junction have been carried out on samples first exposed to chemical treatments--with fixatives and/or dehydration agents--that are known to induce, or to be inadequate to prevent, artefactual changes of the native state. We report here on the potential of a physical approach to the preparation of samples that combines quick-freezing and freeze-drying (with or without exposure to OsO4 vapours) followed by direct embedding of the samples in various resins. Thin sections from physically processed frog neuromuscular junctions, when compared to their chemically fixed counterparts, exhibit an overall excellent preservation, with the organelles retaining their native density and shape. These preparations were also investigated by electron spectroscopic imaging and electron energy loss spectroscopy, obtaining high resolution maps of native total calcium distribution within the nerve terminal. Finally, thin sections from analogously processed, however unfixed, preparations embedded in Lowicryl, were immunogold labelled before exposure to OsO4. Nerve-muscle preparations treated this way exhibited adequate preservation of ultrastructure and revealed the distribution of synaptophysin with high sensitivity and resolution. In conclusion, we provide an overview of the potential of the quick-freezing-freeze-drying approach in the study of the neuromuscular junction function.

High-resolution calcium mapping of the endoplasmic reticulum-Golgi-exocytic membrane system. Electron energy loss imaging analysis of quick frozen-freeze dried PC12 cells.

The calcium pools segregated within the endoplasmic reticulum, Golgi complex, exocytic, and other organelles are believed to participate in the regulation of a variety of cell functions. Until now, however, the precise intracellular distribution of the element had not been established. Here, we report about the first high-resolution calcium mapping obtained in neurosecretory PC12 cells by the imaging mode of the electron energy loss spectroscopy technique. The preparation procedure used included quick freezing of cell monolayers, followed by freeze-drying, fixation with OSO4 vapors, resin embedding, and cutting of very thin sections. Conventional electron microscopy and high-resolution immunocytochemistry revealed a high degree of structural preservation, a condition in which inorganic elements are expected to maintain their native distribution. Within these cells, calcium signals of nucleus, cytosol, and most mitochondria remained below detection, whereas in other organelles specific patterns were identified. In the endoplasmic reticulum, the distribution was heterogeneous with strongly positive cisternae (more often the nuclear envelope and stacks of parallel elements that are frequent in quick frozen preparations) lying in the proximity of or even in direct continuity with other, apparently negative cisternae. The Golgi complexes were labeled strongly and uniformly in all cisternae and part of their vesicles, with no appreciable differences along the cis-trans axis. Weaker or negative signals were recorded from the trans-Golgi network elements and from scattered vesicles, whereas in contrast secretion granules were strongly positive for calcium. These results are discussed in relation to the existing knowledge about the mechanisms of calcium transport in the variations organelles, and about the processes and functions regulated by organelle lumenal calcium in eukaryotic cells.

High resolution ultrastructural mapping of total calcium: electron spectroscopic imaging/electron energy loss spectroscopy analysis of a physically/chemically processed nerve-muscle preparation.

We report on a procedure for tissue preparation that combines thoroughly controlled physical and chemical treatments: quick-freezing and freeze-drying followed by fixation with OsO4 vapors and embedding by direct resin infiltration. Specimens of frog cutaneous pectoris muscle thus prepared were analyzed for total calcium using electron spectroscopic imaging/electron energy loss spectroscopy (ESI/EELS) approach. The preservation of the ultrastructure was excellent, with positive K/Na ratios revealed in the fibers by x-ray microanalysis. Clear, high-resolution EELS/ESI calcium signals were recorded from the lumen of terminal cisternae of the sarcoplasmic reticulum but not from longitudinal cisternae, as expected from previous studies carried out with different techniques. In many mitochondria, calcium was below detection whereas in others it was appreciable although at variable level. Within the motor nerve terminals, synaptic vesicles as well as some cisternae of the smooth endoplasmic reticulum yielded positive signals at variance with mitochondria, that were most often below detection. Taken as a whole, the present study reveals the potential of our experimental approach to map with high spatial resolution the total calcium within individual intracellular organelles identified by their established ultrastructure, but only where the element is present at high levels.