Transfer of functional insulin receptors to receptor-deficient target cells.

Purified human insulin receptors incorporated into phospholipid vesicles have previously been shown to retain insulin binding as well as insulin-stimulated beta-subunit autophosphorylating activity. These vesicles were used as a vehicle to transfer receptors to the insulin receptor-deficient Madin-Darby canine kidney (MDCK) cell line. Fusion of control [14C] dioleoylphosphatidylcholine-labeled phospholipid vesicles with MDCK cells was found to be dependent on both the amount of time and the concentration of polyethylene glycol used for fusion. Optimal insulin receptor transfer, as determined by recovery of [125I]insulin binding, occurred when MDCK cells were incubated for 45 min at 37 C in the presence of 15% polyethylene glycol plus receptor-containing vesicles. Scatchard analyses for insulin receptor binding before and after vesicle fusion demonstrated no postfusion alteration in insulin receptor affinity and a 10-fold increase in the number of insulin receptors present in the MDCK cells. Fusion transfer of insulin receptors to MDCK cells rendered the cells sensitive to insulin (10-100 nM) for stimulation of glycogen synthesis. Chloroquine (0.1 mM) was found to block endosomal processing of receptor-bound [125I] insulin within 1 h. These findings indicate that insulin receptors function as dissociable units which can be inserted into target plasma membranes with resultant recoupling to cellular systems.

[Tibiotarsal and subtalar instability of the ankle. Importance of an original dynamic test in the treatment choice. Experimental study and clinical application]. / Instabilité tibio-tarsienne et sous-astragalienne de la cheville. Apport d'un testing dynamique original dans le choix thérapeutique. Etude expérimentale et applications cliniques.

Various ligamentoplasties are available allowing formation of new proprioceptive chains in cases of failure of physiotherapy. Most of these plasties sacrifice half or all of the fibulolateral tendon, causing stiffness of the subtalar joint. This is a too serious complication to accept for simple tibiotarsal instability: hence the importance of preoperative assessment to determine the type of plasty most appropriate for each type of instability. We have designed an adjustable boot, linked to a dynamometer by means of a metal rod, with a radiological marker attached to the boot, to measure subtalar mobility preoperatively. We studied this boot with the ankles of 15 cadavers, on which we sectioned the ligaments of the tibiotarsal and subtalar joints to measure the degree of laxity. Accurate assessment is possible if the mobility of the tibiotarsal and subtalar joints is measured in cases of acute sprain, in particular in isolated lesions of the anterior talofibular ligament and lesions of the calcaneofibular ligament; or in chronic instability, including: purely tibiotarsal, purely subtalar, and mixed types. This method allows optimal therapeutic choice.

[Reflections on a small series of cementless total hip prostheses]. / Réflexions à propos d'une courte série de prothèses totales de hanche sans ciment.

We report on our series of 48 patients with uncemented hip prostheses, with an average follow-up of 3 years. The clinical results, according to the Merle d'Aubigné's classification, are comparable to those obtained with cemented prostheses except for transitory pain, very often localized to the lateral aspect of the thigh, which seems to be correlated with the bone adaptation to the implant. Radiological findings are valuable in the assessment of long-term results with uncemented prostheses. During the operation, it is of utmost importance that the surgeon obtain a very tight fit of the prosthesis into the bone, which must be confirmed on postoperative X-ray. Under such conditions, the radiological appearance remains the same, showing a condensation line outlining the cup and absence of radiolucent lines along the stem. On the other hand, cortical thickening, bony condensation around the tip of the stem and sclerotic lines are the radiological evidence of bone adaptation to the prosthesis. They are not indicative of a less good result. Finally, radiolucent lines wider than 1 millimeter, extending along the stem, or a progressive sinking of the femoral component are the radiological signs of implant instability. In these rare cases, the prognosis may be compromised.