Upper motor neuron assessment in amyotrophic lateral sclerosis using the patellar tendon reflex and motor-evoked potentials to the lower limbs.

Amyotrophic lateral sclerosis (ALS) diagnosis relies on signs of progressive damage to both lower motoneuron (LMN), given by clinical examination and electromyography (EMG), and upper motoneuron (UMN), given by clinical examination only. Recognition of UMN involvement, however, is still difficult, so that diagnostic delay often remains too long. Shortening the time to clinical and genetic diagnosis is essential in order to provide accurate information to patients and families, avoid time-consuming investigations and for appropriate care management. This study investigates whether combined patellar tendon reflex recording with motor-evoked potentials to the lower limbs (T-MEP-LL) is relevant to assess corticospinal function in ALS, so that it might serve as a tool improving diagnosis. T-MEP-LL were recorded in 135 patients with suspected motor neuron disease (MND) from February 2010 to March 2021. The sensitivity, specificity, and ability to improve diagnosis when added to Awaji and Gold Coast criteria were determined. The main finding of the study is that T-MEP-LL can detect UMN dysfunction with a 70% sensitivity and 63% specificity when UMN clinical signs are lacking. The sensitivity reaches 82% when considering all MND patients. Moreover, at first evaluation, using T-MEP-LL to quantify reflex briskness and to measure central conduction time, can improve the diagnostic accuracy. T-MEP-LL is easy to perform and does not need any electrical stimulation, making the test rapid, and painless. By the simultaneous quantification of both UMN and LMN system, it could also help to identify different phenotype with more accuracy than clinical examination in this broad-spectrum pathology. The question whether T-MEP-LL could further be a real biomarker need further prospective studies.

Amino Acids Content in Germinating Seeds and Seedlings from Castanea sativa L.

During germination the chestnut (Castanea sativa L.) var ecotype 33 accumulates a large amount of asparagine in the cotyledons. This compound also accumulates in the growing axis:shoots and roots. In the cotyledons, gamma-aminobutyrate (GABA) represents a major amino compound during germination and early seedling growth. In young seedlings, 35 days old, arginine predominates over the other soluble amino acids, particularly in roots. Five enzymic activities involved in arginine and GABA have been measured in the storage organ of the seed: arginase and ornithine carbamyltransferase decrease during germination indicating the slowing down of the urea cycle. In contrast, ornithine aminotransferase increases. Glutamate decarboxylase is particularly active about 21 days after imbibition and GABA aminotransferase activity decreases during germination. These two activities are in good agreement with the likely transport of GABA from cotyledons to growing axis. Asparagine, arginine, and GABA are the three amino compounds obviously involved in the mobilization of nitrogen reserves in the germinating chestnut seeds Castanea sativa.