No abstract

We have studied the effect of extradural compliance and extradural resistance on the spread of extradural analgesia. In 111 patients aged 21-75 yr, compliance and resistance of the extradural space were calculated by a mathematical analysis (using the Windkessel theory) of the extradural pressure-response curve to injection of a given volume of local anaesthetic. The calculated mean extradural compliance was 0.39 (SD 0.13) ml mm Hg-1 and this increased with advancing age (P less than 0.01). The total number of analgesic segments blocked was related to extradural compliance (P less than 0.01). Segmental dose requirement was related inversely to extradural compliance (P less than 0.01). Calculated extradural resistance was 26.8 (14.5) mm Hg s ml-1 and this decreased with advancing age (P less than 0.05). The total number of analgesic segments blocked was related inversely to extradural resistance (P less than 0.05). Segmental dose requirement was related to extradural resistance (P less than 0.05).

Distinctive abnormality in the organization of keratin intermediate filaments (KIFs) was found for the first time in cultured epidermal keratinocytes from two patients with hereditary epidermolysis bullosa simplex (EBS), which showed cleavages above the basement membrane zone due to the fragility of basal cells. KIFs in EBS keratinocytes revealed an irregular radial arrangement composed of sparse but thick KIF bundles. Furthermore, these KIF bundles in many cells changed into numerous ball-like keratin aggregates and disappeared beyond these keratin aggregates in the peripheral cytoplasm. Electron microscopy of cultured EBS keratinocytes showed that many ball-like structures consisting of fine filaments or granules or homogeneous substances were scattered in the peripheral regions of the cell attaching to the dish, and intermediate filaments appeared to be emanating from or surrounding the structures. These ball-like keratin aggregates have never been observed in normal human keratinocytes.

We have studied the effects of i.v. bolus doses of magnesium sulphate (MgSO4) 60, 90 and 120 mg kg-1 on haemodynamic state, the coronary circulation and myocardial metabolism in nine dogs anaesthetized with pentobarbitone and fentanyl. MgSO4 produced dose-dependent decreases in arterial pressure, heart rate, left ventricular dP/dtmax and left ventricular minute work index (LVMWI) and an increase in the time constant of left ventricular isovolumic relaxation. Stroke volume increased, systemic vascular resistance decreased and cardiac output did not change significantly. MgSO4 produced decreases in coronary perfusion pressure, coronary vascular resistance and myocardial oxygen consumption (MVO2). Coronary sinus blood flow, lactate extraction ratio and the ratio of LVMWI to myocardial MVO2, that is an index of cardiac efficiency, did not change significantly. This study indicated that the depressant effect of MgSO4 on cardiac function was offset by lowering of peripheral vascular resistance, so that cardiac pump function remained effective, and the almost constant coronary sinus blood flow resulted from the decrease in coronary vascular resistance even at higher doses.

It has been suggested that pemphigus antibodies (PA) react with the surface molecules on keratinocytes, and induce the production and release of proteases resulting in acantholysis. If this is the case, the immunoreactions on the cell surface may send signals to the interior of the cell across the membrane. The present study was carried out to determine whether or not cytoskeletons [microtubules (MT) and keratin-intermediate filaments (KIF)] respond to PA-immunoreactions in cultured human keratinocytes, by indirect immunofluorescence microscopy using anti-keratin and anti-alpha-tubulin antibodies. During incubation for 30 min to 72 h in a PA-containing medium with a normal concentration of Ca2+ (1.2 mM), no changes in MT or KIF organization were detected. Alterations in the organization of these filaments were observed 96 h after addition of PA. When cells grown in a normal medium for 5-7 days were transferred to a medium containing PA and a low level of Ca2+ (0.07-0.14 mM) the reorganization of KIFs and MTs occurred after 1 h incubation. However, no reorganization of the cytoskeletons was detected in the absence of cell detachment. These observations suggest that the pemphigus antibody-induced reorganization of MTs and KIFs does not precede acantholysis and is probably secondary to it, but is not a direct transmembrane response. The present study also showed that immunofluorescence microscopy of KIFs may be one of the most sensitive methods for detecting early cell-to-cell dissociation in cultured keratinocytes.