Factors influencing the relation between corticospinal output and muscle force during voluntary contractions

The mechanisms by which voluntary forces of different strengths are produced in human muscles are not clear. We studied the relation between force and surface electromyography (sEMG) variables over a wide range of voluntary contraction strengths of biceps brachii (BIC) and abductor digiti minimi (ADM). The relation between force and motor evoked potentials (MEPs) to transcranial magnetic stimulation of motor cortex was also assessed. The root mean square of sEMG and median frequency (Mf) of the sEMG power spectrum as well as the MEP area of ADM and BIC were calculated up to the maximum voluntary contraction (MVC). The root mean square of ADM and BIC increased with increasing force levels up to the MVC. The Mf of BIC increased with force levels up to 70% MVC after which it rapidly declined. The Mf of ADM peaked at 40% MVC to slowly decline thereafter. The MEP changes with force were similar to Mf changes. Thus, corticospinal output, as tested by the Mf and MEPs, does not parallel force increments across the contraction range. This decline, which is contingent on the relative contribution of motor unit recruitment and rate coding to force production in each muscle, may depend on reduced motoneurone responsiveness at high firing rates. We suggest that, under controlled conditions, the frequency content of the sEMG signal may be taken to indicate motor unit recruitment range. This information may improve the utility of the Mf to enable evaluation of voluntary activation under different conditions.     

Ancient schwannoma arising in a lymph node: report of a case and review of the literature

We report a case of an intranodal schwannoma in a 79-year-old woman. The patient underwent a left colectomy for a colonic adenocarcinoma, with regional lymph node dissection. Macroscopic examination of the specimen revealed a well-circumscribed 4 cm nodule located in the pericolic fat. Macroscopically, it was interpreted as a metastatic lymph node. Microscopically, the nodule was composed of a proliferation of bland spindle cells, was immunohistochemically positive for S100 protein, and negative for smooth muscle actin, desmin, and cytokeratin. The pathological findings led to the diagnosis of a very rare case of primary schwannoma of the lymph node.     

Tricyclic heteroaromatic systems. Synthesis of 1,3 and 1,2 disubstituted [1]benzopyrano[4,3-b]pyrrol-4-ones and structure-activity relationships as benzodiazepine receptor ligands.

The synthesis of some 1,3- and 1,2- disubstituted [1]benzopyrano-pyrrol-4-ones is reported as well as their benzodiazepine receptor affinity, as measured by the ability to displace [3H]flunitrazepam from its specific central binding. The structure-activity relationships on the whole series of disubstituted [1]benzopyrano-pyrrol-4-ones show the importance of the presence of the 1-aryl substituent and the size limitation of the 3-substituent. The size of the latter seems also to be important for the "in vitro" efficacy.     

Viral load and CD69 molecule expression on freshly isolated and cultured mitogen-stimulated lymphocytes of children with perinatal HIV-1 infection

HIV-1 in adults changes the proportion of mitogen-stimulated lymphocytes expressing the CD69 activation molecule, but little is known about this molecule expression on lymphocytes of HIV-1-infected (HIV-1+) children. Freshly isolated CD3+, CD4+, CD8+ and CD19+ and phytohaemagglutinin (PHA)-stimulated CD3+, CD4+ and CD8+ lymphocytes co-expressing CD69 were investigated cross-sectionally (adopting a MoAb double-staining technique) in 24 HIV-1+ children with severe disease and given anti-retroviral therapy and in 24 age-matched healthy children. CD69 results in HIV-1+ children were correlated with plasma HIV-1 RNA load prospectively determined. HIV-1+ compared with healthy children had higher frequencies of freshly isolated CD3+CD69+ (2.4 +/- 2.2% versus 0.9 +/- 0.5%; P = 0.002) and CD8+CD69+ (1.5 +/- 1.1% versus 0. 5 +/- 0.2%; P < 0.0001) lymphocytes. The frequencies of CD4+CD69+ and CD19+CD69+ lymphocytes were similar. High viral load correlated with an elevated proportion of freshly isolated CD3+CD69+ and CD8+CD69+ lymphocytes. HIV-1+ children showed reduced frequencies of PHA-stimulated CD3+CD69+ (60.7 +/- 7.6% versus 86.1 +/- 7.6%; P < 0. 001), CD4+CD69+ (73.6 +/- 18.2% versus 92.6 +/- 5.1%; P < 0.001), and CD8+CD69+ (51.0 +/- 19.1% versus 65.3 +/- 15.4%; P = 0.007) lymphocytes. Virologic worsening within 6 months correlated with a low proportion of PHA-stimulated CD3+CD69+ and CD8+CD69+ lymphocytes. CD69 molecule expression reflected the coexistence of immune activation and immune deficiency in HIV-1 infection. Changes partly differed from those observed in HIV-1+ adults. CD8+CD69+ (but not CD4+CD69+) lymphocyte proportion correlated with virologic course, and an impaired ability of CD8+ lymphocytes to express CD69 upon PHA stimulation preceded a virologic worsening.     

GLUCOSE INFUSION IN THE PREGNANT RABBIT AND ITS EFFECT ON GLYCOGEN CONTENT AND ACTIVITY OF FOETAL HEART UNDER ANOXIA1

The object of the present study was to determine the possibility of increasing the glycogen content of the foetal myocardium, and thus its ability to survive under anoxic conditions, by infusing glucose in the mother animal before delivery. The material consisted of 41 rabbits; 23 were given a glucose infusion, and 18 served as controls. On the 29th day of pregnancy, a solution of 30% glucose was infused over a 6-hour period. Immediately after the infusion, the mother was sacrificed, and the foetuses delivered abdominally. They were maintained at 37°C, but without the possibility of lung aeration. The ECG of one foetus in each litter was recorded until no heart activity remained. Concurrently, the other foetuses were sacrificed at irregular intervals, and studied with respect to the glycogen content of heart and liver, blood pH and blood glucose. These parameters were correlated to foetal heart activity. It was found that glucose infusion in the mother did, in fact, increase the glycogen content of the foetal heart. This, in turn, seemed to increase the ability of the foetal heart to continue its activity under anoxic conditions.