Temporal relationships among changes in the RR-interval and the powers of the low- and high-frequency components of heart rate variability in normal subjects.

Spectral analysis of heart rate variability (HRV) is widely used as a non-invasive method to assess the cardiovascular autonomic function. Of the two main frequency components of HRV, namely low-frequency (LF, 0.04-0.15 Hz) and high-frequency (HF, 0.15-0.4 Hz) components, it is generally accepted that the HF power reflects modulation of heart rate which is mediated by cardiac parasympathetic (vagal) nerve activity. In contrast, the origin and functional correlates of the LF component are still controversial. Although several lines of evidence have indicated a close correlation between LF power and the baroreflex modulation of autonomic outflows, the detailed mechanisms underlying the genesis of the LF component remain unclarified. In this study, we conducted an ultra-short-term (UST) spectral analysis of R-R interval (RRI) time series using Fast Fourier Transform (FFT) with 5- and 25-s windows to clarify the temporal relationships among transient changes in the RRI and, LF and HF powers in healthy subjects. We found that during active standing, transient RRI increases occurred sporadically. The UST spectral analysis revealed that this RRI increase was associated with a simultaneous increase in HF power which was closely linked to the prominent LF power increase. These results indicate that during active standing, increases in LF and HF powers occur simultaneously, and they may reflect enhanced cardiac vagal activity which generates transient bradycardia.

Expression patterns of beta1-related alpha integrin subunits in murine lens during embryonic development and wound healing.

PURPOSE: To study the expression patterns of b1-related alpha integrin subunits in murine lens epithelial cells, comparing embryonic fiber differentiation with injury-induced epithelial mesenchymal transition (EMT). METHODS: Adult mice type C57BL/6, pregnant as well as with an eye injured, were sacrificed at different time-course intervals. The embryonic and the injured eyes were obtained and deparaffinized sections of these eyes were processed for immunohistochemistry staining for detection of integrin a subunits. RESULTS: Embryonic lens epithelial cells expressed primarily a3 and a5 subunits, whereas embryonic fiber cells expressed a2, a5, and a6 subunits. Adult lens epithelial cells expressed a3, and a6 subunits,whereas injured lens cells expressed a2, a3, and a6 integrin subunits. CONCLUSIONS: The phenotypic changes of lens epithelial cells during embryonic fiber differentiation and EMT are characterized by different expression of integrin subunits as a result both of the altered extracellular matrix conditions and of the altered cell signaling pathways recruited in each process.

Cornea with Peters' anomaly: perturbed differentiation of corneal cells and abnormal extracellular matrix in the corneal stroma.

PURPOSE: We examined histopathologically the anterior ocular segment including the cornea and lens of an eye which had been enucleated in a patient with Peters' anomaly because of untreatable corneal perforation. Special effort was made to differentiate the corneal stromal and endothelial cells, and the stromal extracellular matrix. METHODS: Light microscopy, with hematoxylin and eosin staining, and transmission electron microscopy were employed. RESULTS: Corneal endothelial cells and Descemet's membrane were not detected in the central cornea, where there were immature cells with a fibroblastic configuration. The inner surface of the peripheral cornea was covered with cells containing pigment granules in the cytoplasm. Cell density in the central corneal stroma was relatively high. The diameter of the stromal collagen fibrils was not uniform. A mature collagen fibril-free area was also seen in the central corneal stroma. CONCLUSIONS: Differentiation of neural crest-derived cells in corneal stroma and endothelium might have been perturbed in the cornea of this patient with Peters' anomaly, inducing the defect in the corneal endothelium and the qualitative and quantitative abnormalities of the extracellular matrix.