Caveolin-1 expression and membrane cholesterol content modulate N-type calcium channel activity in NG108-15 cells.

Caveolins are the main structural proteins of glycolipid/cholesterol-rich plasmalemmal invaginations, termed caveolae. In addition, caveolin-1 isoform takes part in membrane remodelling as it binds and transports newly synthesized cholesterol from endoplasmic reticulum to the plasma membrane. Caveolin-1 is expressed in many cell types, including hippocampal neurons, where an abundant SNAP25-caveolin-1 complex is detected after induction of persistent synaptic potentiation. To ascertain whether caveolin-1 influences neuronal voltage-gated Ca2+ channel basal activity, we stably expressed caveolin-1 into transfected neuroblastoma x glioma NG108-15 hybrid cells [cav1(+) clone] that lack endogenous caveolins but express N-type Ca2+ channels upon cAMP-induced neuronal differentiation. Whole-cell patch-clamp recordings of cav1(+) cells demonstrated that N-type current density was reduced in size by approximately 70% without any significant change in the time course of activation and inactivation and voltage dependence. Moreover, the cav1(+) clone exhibited a significantly increased proportion of membrane cholesterol compared to wild-type NG108-15 cells. To gain insight into the mechanism underlying caveolin-1 lowering of N-current density, and more precisely to test whether this was indirectly caused by caveolin-1-induced enhancement of membrane cholesterol, we compared single N-type channel activities in cav1(+) clone and wild-type NG108-15 cells enriched with cholesterol after exposure to a methyl-beta-cyclodextrin-cholesterol complex. A lower Ca2+ channel activity was recorded from cell-attached patches of both cell types, thus supporting the view that the increased proportion of membrane cholesterol is ultimately responsible for the effect. This is due to a reduction in the probability of channel opening caused by a significant decrease of channel mean open time and by an increase of the frequency of null sweeps.

Functional and psychological recovery during intensive hospital rehabilitation following cardiac surgery in the elderly.

UNLABELLED: The recovery process in the elderly after cardiac surgery is influenced not only by clinical cardiac conditions, but also by comorbidity, cognitive decline and disability. We evaluated the relationship between clinical objective and self-perceived factors and their influence on functional recovery in 204 consecutive, over-70s pts who were admitted into an intensive hospital rehabilitation program following cardiac surgery. The variables taken into consideration were: comorbidity (Charlson index), length of hospital stay and complications in cardiac surgery and rehabilitation, disability (nursing needs score index), functional status (6-min walking test), left ventricular EF, number of training sessions, self-perceived health status (EuroQol questionnaire), emotional impairment (anxiety/depression, CBA-2.0/interview). RESULTS: Functional capacity: the distance walked was 198 +/- 103 m at admission and 287 +/- 121 m at discharge (p < 0.0001). Only the nursing needs score index resulted as a weak, independent predictor of the distance walked at admission (r2 = 0.14, p < 0.001, beta = 0-.21), which (beta = 0.49), together with complications during rehabilitation (beta = -0.15), self-perceived health status at discharge (beta = 0.15) and number of training sessions (beta = 0.20), was independently correlated with the distance walked at time of discharge (r2 = 050, p < 0.0001). Patients mood: anxiety correlated with depression. Emotional scores did not correlate with functional measures. Patients self-perceived health status: only the nursing needs score index was a weak, independent predictor of well-being at entry (r2 = 0.15, p < 0.0001, beta = -0.29), which, in turn, was the only predictor of perception at discharge (r2 = 0.33, p < 0.0001, beta = 0-.42). CONCLUSIONS: In an intensive hospital rehabilitation program following cardiac surgery in patients over 70 a) there was no correlation between clinical and psychological variables; b) anxiety and depression were associated, but neither influenced the recovery process nor correlated to health status perception; c) functional impairment was strongly influenced by nursing needs which also affected the self-perceived health status; d) both functional and perception recovery were influenced by disability at time of admission and reacted positively after rehabilitation.

In vitro production of lymphocyte and granulocyte proliferation inhibitors (chalones?) from living cells.

Media conditioned with viable rat and calf spleen lymphocytes were seen to be able to inhibit 3H-thymidine uptake by rat thymocytes and the mitogenic response of human lymphocytes to PHA but not bone marrow cells proliferation. The inhibitor appeared to have a molecular weight greater than 50,000 daltons, as determined by Amicon Diaflo ultrafiltration. Media conditioned with rat granulocytes had a similar tissue specific but species non-specific inhibitory action. Also human leukemic cells appeared able to produce in vitro an inhibitor of cell proliferation when a certain degree of differentiation was present.