Biomedical subjects

L Charron

Publications and source records attributed to L Charron.

23 records · Page 2Linked to original sources

PubMed1978

Polyneuropathy and folate deficiency.

We studied five patients (two men and three women, age between 58 and 76 years) with clinical and electrophysiological signs of polyneuropathy. Routine neurological, hematological, and gastroenterological studies as well as procedures to test fat malabsorption were performed. Folate determinations were done using both radioactive and Lactobacillus casei methods. Two patients displayed the signs of subacute combined degeneration of the spinal cord with polyneuropathy, while three had only signs of neuropathy. All had low serum folate concentration, long-standing gastrointestinal disease, and deficient folate intake. The D-xylose absorption test gave values in all patients, while none displayed the classical malabsorption syndrome. The patients had substantial improvement or recovered (according to clinical and electrophysiological measurements) after periods ranging from 9 to 39 months of folate therapy. Such acquired folate-responsive polyneuropathy has two principal characteristics: mixed sensorimotor with mainly sensory deficits, and involvement of one or both of the lower extremities much more extensively than the upper extremities.

Aged↗

PubMed1976

Multipotentiality of Schwann cells in cross-anastomosed and grafted myelinated and unmyelinated nerves: quantitative microscopy and radioautography.

Cross-anastomoses and autogenous grafts of unmyelinated and myelinated nerves were examined by electron microscopy and radioautography to determine if Schwann cells are multipotential with regard to their capacity to produce myelin or to assume the configuration seen in unmyelinated fibres. Two groups of adult white mice were studied. (A) In one group, the myelinated phrenic nerve and the unmyelinated cervical sympathetic trunk (CST) were cross-anastomosed in the neck. From 2 to 6 months after anastomosis, previously unmyelinated distal stumps contained many myelinated fibres while phrenic nerves joined to proximal CSTs became largely unmyelinated. Radioautography of distal stumps indicated that proliferation of Schwann cells occurred mainly in the first few days after anastomosis but was also present to a similar extent in isolated stumps. (B) In other mice, CSTs were grafted to the myelinated sural nerves in the leg. One month later, the unmyelinated CSTs became myelinated and there was no radioautographic indication of Schwann cell migration from the sural nerve stump to the CST grafts. Thus, Schwann cell proliferation in distal stumps is an early local response independent of axonal influence. At later stages, axons from the proximal stumps cause indigenous Schwann cells in distal stumps from the previously unmyelinated nerves to produce myelin while Schwann cells from the previously unmyelinated nerves to produce myelin while Schwann cells from the previously myelinated nerves become associated with unmyelinated fibres. Consequently, the regenerated distal nerve resembled the proximal stump. It is suggested that this change is possible because Schwann cells which divide after nerve injury reacquire the developmental multipotentiality which permits them to respond to aoxonal influences.

Animals↗

PubMed1976

Potential of Schwann cells from unmyelinated nerves to produce myelin: a quantitative ultrastructural and radiographic study.

In adult mice, most fibres in the cervical sympathetic trunk (CST) are unmyelinated whereas a large proportion of sural nerve fibres are myelinated. This study of nerve grafts in syngeneic mice was designed to determine if Schwann cells originating from the unmyelinated CST would produce myelin when in contact with regenerating axons of the sural nerve. Quantitative microscopy of triated thymidine-labelled CST segments grafted to unlabelled sural nerve stumps revealed that, one month after grafting, previously unmyelinated grafts contained many myelinated fibres. By phase and electron microscope radioautography, nearly 40% of the myelin-producing cells in the reinnervated graft were shown to have originated in the unmyelinated CST. These findings indicate that Schwann cells originating from unmyelinated fibres are able to differentiate into myelin producing cells.

Animals↗

PubMedDate not supplied

Muscle reorganization after partial denervation and reinnervation.

The normal rat tibialis anterior (TA) muscle was found to be innervated by approximately 154 spinal motor cells of which 95 are alpha motoneurons. Most of these axons ran in the L4 root and connected with glycolytic type 2B muscle fibers. The L5 root supplied 8.4% to 14.7% of the motor axons of TA muscle and innervated type 1 and 2A muscle fibers rich in oxidative enzymes. Two months after section of the peroneal nerve, there was marked fiber-type grouping and compact rearrangement of the L4 and L5 motor units. After section of the L4 radicular nerve, the TA muscle remained atrophic with no evidence of fiber-type grouping until 3 months when the L4 regenerating axons reached the muscle. Similar results were obtained after ligation of the divided ends of the L4 radicular nerve, which delayed but did not prevent reinnervation. These data suggest that, after partial denervation, muscle reinnervation by collateral sprouting is a slowly developing process.

Animals↗

PubMedDate not supplied

Patient self-management of continuous subcutaneous insulin infusion.

Continuous subcutaneous insulin infusion (CSII) is one of the ways to control blood glucose for prolonged periods. This study was undertaken to establish the long-term feasibility and efficacy of CSII with patient self-management. Patients were instructed to maintain their calorie and carbohydrate intake. Basal infusion of insulin, representing 50% of the total pre-CSII dose, was supplemented by boluses of insulin based on carbohydrate intake for each meal. With this type of regimen, blood glucose and M-values were easily normalized during the physician-directed periods. This study demonstrated that near-normalization of blood glucose, M-values, and glycosylated hemoglobin was maintained after a 1 1/2-yr period of patient self-management. We attributed this successful management in part to the protocol used, in which boluses were related solely to carbohydrate intake while basal insulin was adjusted according to fasting blood glucose. The chronic normalization of blood glucose resulted in improvement of platelet function as witnessed by responsiveness to antiaggregating (PGE1) and aggregating (epinephrine) agents. An improvement was noticed in doppler measurement of ankle-arm blood pressure and a near-normalization of nerve latency and conductivity was observed.

Adult↗