Bulky Recurrent Juvenile Nasopharyngeal Angiofibroma: Bulky Recurrent Juvenile Nasopharyngeal Angiofibroma

Juvenile nasopharyngeal angiofibroma is a rare and highly vascularized tumor that accounts for 0.05 to 0.5% of all head and neck neoplasms. The aim of this work was to present a case of a large recurrent juvenile nasopharyngeal angiofibroma coexisting with a facial lipoma in a 16-year-old boy. The patient was referred to our institution because of frequent unilateral epistaxis. Computed tomography revealed a hypervascular tumor with ethmoidal cell destruction and spread to the nasopharynx. Operative treatment of nasal cavity tumors was carried out using a transpalatal approach. After 6 months, the recurrence of the angiofibroma was verified radiologically. Primary as well as secondary surgical procedures were assisted with an endoscopic procedure. Accurate preoperative assessment and staging are essential for choosing a surgical procedure. The primary treatment is surgical excision. Early diagnosis, accurate staging, adequate treatment, and regular postoperative follow-up are essential in the treatment of these lesions.

P-120 LAPAROSCOPIC REPAIR OF INCISIONAL HERNIA USING A NON-ABSORBABLE TRANSPARENT COMPOSITE PROSTHESIS TOTALLY IN POLYPROPYLENE - OUR EXPERIENCE

Introduction

Incisional ventral hernia is one of the most common surgical complications after laparotomy. The aim of this retrospective observational study is an evaluation of clinical outcomes after laparoscopic repair of incisional hernias with a non-absorbable and transparent composite prosthesis composed of a macro-porous monofilament polypropylene mesh and a transparent polypropylene film.

Materials and Methods

63 patients, from January 2016 to December 2021, were treated for incisional hernia at Center of minimal invasive surgery Nis, Serbia. The mesh was always positioned intraperitoneally after closing the defects and fixed with absorbable tacks and non-absorbable suture.

Results

In the considered cohort (54% female and 46% male) the median age and BMI were 54 years (range: 39–68) and 25,1 kg/m2 (range: 21.5–30.3), respectively. Concerning hernia position, 93.7% of the hernias were medial, 4.8% lumbar and 1.6% medio-lumbar. According to EHS classification, 58.7% of the hernias were W1, 36.5% W2 and 12.7% W3. The average duration of hospitalization was 2 days.

The rate of early post-operative complications was 6.3%, including 1 seroma (1.6%) and 3 patients reporting pain (4.8%). At a median follow up of 48 months (range: 6–60) we registered 2 cases of hernia recurrency (3.2%, both at 36 months follow-up) and 1 case of bowel obstruction (1.6%). All the considered variables did not result statistically significative in relation to post-operative complications.

Conclusion

Our clinical experience showed that intraperitoneal treatment of incisional hernia using a transparent composite prosthesis. The minimally invasive procedure allows a fast postoperative recovery and a consequent low economical cost.

The meta-signature guided investigation of miRNA candidates as potential biomarkers of oral cancer

OBJECTIVES

This study aimed to experimentally validate dysregulated expression of miRNA candidates selected through updated meta-analysis of most commonly deregulated miRNAs in oral cancer and to explore their diagnostic and prognostic potential.

MATERIALS AND METHODS

Five miRNAs (miR-31-3p, miR-135b-5p, miR-18a-5p, miR-30a-5p, miR-139-5p) from updated meta-signature were selected for validation by qRT-PCR method in 35 oral cancer clinical specimens and adjacent non-cancerous tissue.

RESULTS

Updated meta-analysis has identified 13 most commonly deregulated miRNAs in oral cancer. Seven miRNAs were consistently up-regulated (miR-21-5p, miR-31-3p, miR-135b-5p, miR-31-5p, miR-424-5p, miR-18a-5p, miR-21-3p), while five were down-regulated (miR-139-5p, miR-30a-3p, miR-375-3p, miR-376c-3p, miR-30a-5p). Increased expression of miR-31-3p, miR-135b-5p, as well as decreased expression of miR-139-5p and miR-30a-5p were confirmed in oral cancer compared to adjacent non-cancerous tissue. A three-miRNAs combination (miR-31-3p, miR-139-5p, miR-30a-5p) gave the most promising diagnostic potential for discriminating oral cancer from non-cancerous tissue (AUC: 0.780 (95% CI: 0.673-0.886), p<0.0005, sensitivity 94.3%, specificity 51.4%). High expression of miR-135b-5p, miR-18a-5p and miR-30a-5p was associated with poor survival (p=0.003, p=0.048, p=0.016, respectively).

CONCLUSION

miR-31-3p, miR-139-5p, miR-30a-5p panel was confirmed as a potential diagnostic biomarker when distinguishing oral cancer from non-cancerous tissue. miR-135b-5p, miR-18a-5p and miR-30a-5p might serve as potential biomarkers of poor survival of oral cancer patients.

Facial nerve palsy as the first sign of late breast cancer metastasis to the temporal bone

Introduction. Late metastases of malignant tumors in the temporal bone are very rare lesions. They can be asymptomatic for a long time and usually manifest them-selves in the form of hearing loss, dizziness, tinnitus, and paralysis of the facial nerve. Modern radiological diagnostics and explorative surgery with biopsy are essential for diagnosis. Case report. We present a rare and unusual case of a 66-year-old female patient with facial nerve paralysis that appeared as the first sign of metastatic breast cancer in the temporal bone 10 years after treatment. A sudden hearing loss and dizziness occurred six months later, and the value of CA 15-3 was elevated. Scintigraphy pointed to susceptible metastatic deposits of the axial skeleton without lesions in the temporal bone. Finally, repeated computed tomography revealed osteolytic changes in the temporal bone six months after that. Immunohistochemical analysis of mastoid tissue samples confirmed that it was a breast cancer metastasis. One year after palliative radiotherapy and oral hormone therapy, a patient had a good general condition with a better function of the facial nerve. Conclusion. A high degree of clinical suspicion sometimes requires repeated radio-logical diagnostics in order to detect osteolytic metastatic changes in the temporal bone but also in other bone structures within the hematogenous dissemination of the malignant disease.

Cytomegalovirus induces Interleukin-6 mediated inflammatory response in salivary gland cancer

PURPOSE

The purpose of this study was to examine whether cytomegalovirus (CMV) is present in different histological types of salivary gland cancer (SGC) by detecting CMV immediate-early (IE) and early gene products, and to determine the presence of its association with the overexpression of interleukin (IL)-6.

METHODS

Immunohistochemical analysis of 92 cases of different histological types of SGC was performed to determine the presence of IL-6 and CMV antigen and its intensity in tumor tissue. Twenty samples of normal salivary gland tissue obtained during autopsy served as healthy controls.

RESULTS

CMV antigens were not found in healthy acinar tissue of salivary glands, but were expressed in epithelium of salivary gland ducts. Negative expression of CMV antigens was also found in salivary gland tissue surrounding tumors. On the other hand, CMV was detected in 65/92 SGC cases (70.6%). Higher expression of IL-6 was found in SGC (70.7%) than in normal tissue (20%). There was a high association of CMV antigen presence with the presence of IL-6, and with the IL-6 expression intensity.

CONCLUSIONS

Positive expression of CMV antigens in a high percentage of SGC cells suggests that it might play an important role in carcinogenesis by increasing IL-6 production and leading to inhibition of apoptosis and tumor development.

The MMP-2 and MMP-9 promoter polymorphisms and susceptibility to salivary gland cancer

PURPOSE

Matrix metalloproteinases (MMPs) are a family of endopeptidases that may play an important role in the development of salivary gland cancer (SGC). MMP-2 and MMP-9, members of the gelatinase protein family, are capable of degrading type IV collagen of basement membranes, and their overexpression is often associated with tumor aggressiveness and poor prognosis. The aim of this study was to establish the role of single nucleotide polymorphisms (SNPs) in MMP-2 and MMP-9 genes as putative susceptibility factors for the development of SGC.

METHODS

The MMP-2 -1306 C>T, MMP-2 -1575 G>A and MMP-9 -1562 C>T polymorphisms were analyzed in 93 SGC cases and 100 controls using PCR-RFLP.

RESULTS

The T allele for the MMP-2-1306 C>T polymorphism exhibited its effect in heterozygous carriers, increasing the risk for SGC (odds ratio/OR 1.98, 95% CI 1.07-3.65, p=0.03). According to the dominant model, CT+TT genotypes had a 2-fold increased risk of developing SGCs (p=0.02).When the dominant model was applied for the MMP2 -1575 G>A, individuals with GA+AA genotypes exhibited a 1.77-fold increase in cancer risk, but with borderline significance (p=0.049). Heterozygous carriers of the variant T allele for the MMP-9 -1562 C>T polymorphism had roughly a 2-fold increase in susceptibility for SGC compared to wild type homozygotes (CC) (p=0.02).

CONCLUSION

Our findings suggest MMP-2-1306 C>T and MMP-9-1562 C>T polymorphisms genotypes seem to influence the development of SGCs, whereas MMP-2 -1575 G>A seems to be of a minor importance.

Zygomatic bone metastasis as an initial presentation of hepatocellular carcinoma

Hepatocellular carcinoma is the most common type of primary liver cancer. It metastasizes via blood or through lymphatic dissemination, most comonly to the lungs, abdominal lymph nodes, and bones. Metastases to the bones of the head and neck region, however, are extremely uncommon. A 70-year-old male was presented with a mass in the left zygomatic region. After the incisional biopsy, the histopathologic and immunohistochemical analysis confirmed a metastasis of hepatocellular carcinoma. An abdominal computerized tomography (CT) scan  revealed a large primary tumor in the right liver lobe. To the best of our knowledge, this is the second case of an isolated zygomatic metastasis as an initial presentation of hepatocellular carcinoma. We also reviewed the literature regarding clinical and histopathologic characteristics of hepatocellular carcinoma that produced metastases to the zygomatic bone and the maxilla.

Differentiation and function of human monocyte-derived dendritic cells under the influence of leflunomide

Leflunomide is an immunosuppressive drug effective in experimental models of transplantation and autoimmune diseases and in the treatment of active rheumatoid arthritis (RA). Having in mind that it has been shown that some other immunosuppressive drugs (glucocorticoids, mycophenolate mofetil, sirolimus etc.) impair dendritic cell (DC) phenotype and function, we investigated the effect of A77 1726, an active metabolite of leflunomide, on the differentiation and function of human monocyte-derived dendritic cells (MDDC) in vitro. Immature MDDC were generated by cultivating monocytes in medium supplemented with GM-CSF and IL-4. To induce maturation, immature MDDC were cultured for 2 additional days with LPS. A77 1726 (100 ?M) was added at the beginning of cultivation. Flow cytometric analysis showed that MDDC differentiated in the presence of A77 1726 exhibited an altered phenotype, with a down-regulated surface expression of CD80, CD86, CD54 and CD40 molecules. Furthermore, the continuous presence of A77 1726 during differentiation and maturation prevented successful maturation, judging by the decreased expression of maturation marker CD83, costimulatory and adhesive molecules on A77 1726-treated mature MDDC. In addition, A77 1726-pretreated MDDC exhibited a poor stimulatory capacity of the allogeneic T cells and a low production of IL-10 and IL-18. These data suggest that leflunomide impairs the differentiation, maturation and function of human MDDC in vitro, which is an additional mechanism of its immunosuppressive effect.

Surgical management of cervical paragangliomas

Carotid body tumors are rare, but represent the most common form of head and neck paraganglioma. We present 17 surgically treated patients. The present study reviews our experience in the diagnosis and treatment of these uncommon lesions. At surgery, 11 tumors were classified as Shamblin Class II and six as Class III. A cerebral angiogram was obtained in all cases before surgery. A cervical approach was the method of choice in 16 cases; in one case with mediastinal extension of the tumor we used a combined cervical and transsternal approach. Complete excision of the tumor was accomplished in all cases. Subadventitial tumor excision was performed in eight cases whereas internal carotid artery reconstruction was obtained in eight cases (three saphenous interposition vein grafts, two polytetrafluoroethylene (PTFE) 6 mm grafts, and end-to-end anastomosis in three cases). Resection of the left common carotid artery and reconstruction with a Dacron 8 mm graft was performed in the case with mediastinal tumor extension. Duplex scan along with angiography is effective in making the diagnosis. Excision is indicated for most tumors, and best results are achieved by an experienced vascular surgeon.

Inhibitory effect of select nitrocompounds on growth and survivability of Listeria monocytogenes in vitro

We report the effects of 2-nitro-1-propanol (2NPOH), 2-nitroethanol (2NEOH), and nitroethane (NE) on growth and survivability of Listeria monocytogenes. In all cases, inhibition was greatest with 2NPOH and least with NE. For example, specific growth rates of L. monocytogenes strain 18 declined (P < 0.05) 76, 60, and 29% from controls during aerobic culture at 37 degrees C in brain heart infusion broth containing 10 mM 2NPOH, 2NEOH, or NE, respectively. Mean specific growth rate for the controls incubated likewise without added nitrocompound was 0.62 +/- 0.02 h(-1). Specific growth rates of L. monocytogenes Scott A decreased (P < 0.05) 67, 45, and 11%, respectively, from controls (0.67 +/- 0.02 h(-1)) when cultured similarly. Specific growth rates for L. monocytogenes strain 18 incubated similarly except at 30 degrees C were reduced (P < 0.05) 76, 60, and 30%, respectively, and were reduced (P < 0.05) 78, 23, and 23% during anaerobic culture at 30 degrees C in brain heart infusion broth containing 15 mM 2NPOH, 2NEOH, or NE (control rates ranged from 0.37 +/- 0.07 to 0.74 +/- 0.05 h(-1)). Survivability of L. monocytogenes strain 18 was reduced (P < 0.05) during aerobic storage (4 months at 4 degrees C) in brain heart infusion broth containing 2NPOH or 2NEOH (by 7.8 and 1.9 log units, respectively) but not NE. The inhibitory effect of 2NPOH was approximately 20% greater during growth at pH 7.0 than at pH 5.6 or 8.0. These results demonstrate the differential inhibitory activity of 2NPOH, 2NEOH, and NE against L. monocytogenes in vitro.

Can food-related environmental factors induce different behaviour in two key serovars, 4b and 1/2a, of Listeria monocytogenes?

Listeria monocytogenes isolates (81 in total; 42 isolated from cases of human listeriosis: 39 isolated from food), belonging to serovars 1/2a or 4b, were studied for any group differences between serovars to selected factors associated with foods (two bacteriocins and mild heat treatment), growth kinetics at 37 degrees C and pathogenicity for chick embryos. The isolates were tested for sensitivity to two bacteriocins at 4 degrees C and 37 degrees C, and were tested for the remaining parameters both before and after exposure to cold storage (4 degrees C) with starvation. In addition, the isolates were typed using pulsed field gel electrophoresis (PFGE), multilocus enzyme electrophoresis (MEE) and phage typing to find any correlation between the types and group differences in the chosen parameters. Considerable strain diversity within each L. monocytogenes serovar with respect to the chosen parameters was observed, especially after exposure to cold storage. Nevertheless, the serovar 1/2a isolates, as a group, tended to be more resistant to the two antilisterial bacteriocins at 4 degrees C than the group of serovar 4b isolates. In contrast, after cold storage at 4 degrees C, L. monocytogenes serovar 4b isolates, as a group, tended to be more resistant to heat treatment at 60 degrees C than the group of 1/2a isolates. In addition, the serovar 4b group tended to have shorter lag phases and higher pathogenicity, when transferred from cold storage to body temperature (37 degrees C), than the group of serovar 1/2a isolates. No correlation between PFGE-, MEE- and phage-types and the tested parameters was found. Although the above serovar-related differences were observed only when mean values of the groups were compared (not all isolates within each group followed the group pattern), the results indicate interesting directions for further research.

Leflunomide protects mice from multiple low dose streptozotocin (MLD-SZ)-induced insulitis and diabetes

In certain animal models of autoimmunity the isoxasol derivative leflunomide has been reported to exert a protective effect against autodestruction. In the present study, the immunomodulatory potential of the main metabolite of leflunomide, A77 1726, in experimentally induced autoimmune diabetes was investigated. The disease was induced in genetically susceptible CBA/H mice by multiple low doses of streptozotocin (MLD-SZ, 40 mg/kg per day, given intraperitoneally for 5 consecutive days). Effects of leflunomide were evaluated by two treatment protocols: mice treated with MLD-SZ were injected intraperitoneally with A77 1726 for 10 consecutive days, either during the first 10 days of the disease (early treatment), or starting from day 10 after disease induction (late treatment). Disease manifestations defined by hyperglycaemia, mononuclear infiltration into pancreas, expression of interferon-gamma (IFN-gamma) and inducible nitric oxide synthase (iNOS) and destruction of the islets of Langerhans were reduced in a dose-dependent fashion after early treatment with A77 1726 (dose range of 5-35 mg/kg per day). Moreover, late treatment with the high dose of the drug (25 mg/kg per day), started when the autoimmune disease was already apparent, arrested progression of ongoing inflammatory response. Analysis of the effects of A77 1726 on the adhesive interactions of spleen-derived or peripheral blood-derived mononuclear cells from MLD-SZ-treated and normal mice demonstrated that the drug inhibits both ex vivo and in vitro spontaneous mononuclear cell aggregation, thus suggesting that an important component of leflunomide's immunomodulatory action is suppression of adhesive interactions. These results demonstrate both preventive and therapeutic effects of leflunomide in a model of MLD-SZ-induced diabetes and suggest that the drug may be considered a potent therapeutic tool for autoimmune inflammatory disorders, including diabetes.

The involvement of immune reactions in cardiac damage during acute myocardial infarction: role of cell-mediated immune response

This study was undertaken with the aim of investigating humoral and cell-mediated immune response in acute myocardial infarction (AMI) as possible mechanisms involved in the infarction enlargement. Twenty three patients with first AMI and 15 healthy volunteers were examined. Of the AMI patients, 14 had extensive infarction (group A), while 9 patients had small infarction (group B). Immunologic analyses were performed at admission, and repeated after 3, 7, 14 and 21 days of the acute event. Following parameters were tested: number of CD3+, CD4+, CD8+ and CD20+ cells; serum IgG, IgA, IgM, C3, C4, immune complex and anticardiac antibody levels; polymorphonuclear cell (PMN) function (chemotaxis, phagocytosis, metabolic activity); leukocyte migration in vitro in the presence of water-soluble homologous heart extract. It was demonstrated that the number of B cells, serum IgG, C3, immune complex and anticardiac antibody levels were elevated from 7th-14th days after AMI. Concerning these parameters, however, no significant differences were obtained between group A and group B of AMI patients. Chemotaxis and metabolic activity of peripheral blood PMN, but not phagocytosis, were enhanced during AMI, again changes of PMN did not correlate with the extension of infarction. In contrast, leukocyte migration inhibition in vitro revealed that only patients with extensive AMI have developed positive reaction during the first 14 days after the onset of the disease, while leukocyte inhibition reaction appeared in patients with nonextensive AMI not earlier than the 21st day after the infarction. These findings demonstrate generation of immune reactivity during AMI and indicate that humoral immune response seems more likely to be an epiphenomenon related to tissue necrosis, while cell-mediated immune reactions could influence the extensiveness of cardiac damage.

Leflunomide, a novel immunomodulating drug, inhibits homotypic adhesion of peripheral blood and synovial fluid mononuclear cells in rheumatoid arthritis

OBJECTIVE AND DESIGN

A novel immunomodulating drug, leflunomide has been shown recently to be effective and well tolerated in patients suffering from rheumatoid arthritis (RA). The present study evaluated the effect of the drug on cell adhesion in RA.

MATERIAL AND TREATMENT

Peripheral blood and synovial fluid mononuclear cells were obtained from a clinical trial, undertaken primarily to evaluate the efficacy and pharmacokinetic profile of multiple-dose pulsing leflunomide therapy in RA patients. PB MNC and corresponding synovial fluid (SF) MNC for in vitro homotypic aggregation (HA) assay were obtained from healthy volunteers and RA patients with active disease not treated with leflunomide in vivo.

METHODS

Expression of activation antigens (CD25, CD54, CD69, CD71, HLA-DR) on peripheral blood mononuclear cells (PB MNC), as well as ex vivo ability of cells to aggregate spontaneously were determined in patients before entering into the clinical trial and at the end of 6 months treatment. HA was measured by aggregation in vitro. Data were compared by Student's t-test.

RESULTS

There was a decreased expression of activation antigens and decreased spontaneous MNC clustering after leflunomide therapy. We found in the in vitro study that HA of PB and SF MNC was mainly mediated through beta 2-integrin molecules. The active metabolite of leflunomide, A77 1726, effectively suppressed both spontaneous and phorbol-ester (PMA)-induced HA. Disruption of cell aggregates by A77 1726 was dose-dependent and, most likely, unrelated to the quantitative modulation of integrin receptors.

CONCLUSIONS

Results from this study support the idea that leflunomide elicits its immunomodulatory action, at least partially, by modulating the adhesion process.

Safety and effectiveness of leflunomide in the treatment of patients with active rheumatoid arthritis. Results of a randomized, placebo-controlled, phase II study

OBJECTIVE

To assess the safety and effectiveness of leflunomide versus placebo in patients with active rheumatoid arthritis (RA) treated for 6 months.

METHODS

Four hundred two patients were randomly assigned to receive placebo or leflunomide at 5 mg, 10 mg, or 25 mg daily. A washout period of 6-12 weeks from prior second-line therapy was required.

RESULTS

Statistically significant improvement in primary and secondary outcome measures, as well as by responder analyses, occurred in the 10-mg and 25-mg dosage groups compared to placebo. Twenty-one patients (7.0%) in the active treatment groups withdrew due to adverse events (AEs). The incidence of AEs was higher with leflunomide than with placebo. Gastrointestinal symptoms, weight loss, allergic reactions, skin rash, and reversible alopecia were more common in the 10-mg and 25-mg dosage groups. The incidence of infections was similar between the treatment and placebo groups; no opportunistic infections were seen. Transient elevations in liver function studies were noted in a small number of patients.

CONCLUSION

Leflunomide is effective in daily doses of 10 mg and 25 mg in patients with active RA. Improved efficacy at the 25-mg dose was associated with a higher incidence of AEs. Randomized, placebo-controlled trials using daily doses of 10 mg and 20 mg are under way in the US and Europe to confirm these positive results.

Leflunomide (HWA 486), a novel immunomodulating compound for the treatment of autoimmune disorders and reactions leading to transplantation rejection

Leflunomide has been shown to be very effective in preventing and curing several autoimmune animal diseases. Further, this agent is as effective as cyclosporin A in preventing the rejection of skin and kidney transplants in rats. Preliminary results from patients suffering from severe cases of rheumatoid arthritis demonstrated that clinical and immunological parameters could be improved with leflunomide therapy. Mode of action studies revealed that this substance antagonizes the proliferation inducing activity of several cytokines and is cytostatic for certain cell types. In this light, we could show that tyrosine phosphorylation of the RR-SRC peptide substrate and the autophosphorylation of the epidermal growth factor (EGF) receptor were, dose dependently, inhibited by leflunomide. EGF activates the intrinsic tyrosine kinase of its receptor, which stimulates the phosphorylation of a variety of peptides, the amino acid residue in all cases is tyrosine. These results indicate that much of leflunomide's activity could be due to the inhibition of tyrosine-kinase(s), which is an important general mechanism for the proliferation of various cell types. Thus, leflunomide, which is effective against autoimmune diseases and reactions leading to graft rejection, would seem to have a mode of action separating it from known immunosuppressive drugs.

Neurophysiological approaches to chronic pain following spinal cord injury

Pain occurring in patients with spinal cord injury can be classified on clinical grounds into five types: peripheral, central, visceral, mechanical and psychic. An attempt has been made to correlate each type of pain with present neurophysiological knowledge. Mechanisms as to how unpleasant sensations reach the conscious level can be deduced when clinical and neurophysiological data are pooled. Eight case histories are presented which typify each class. The authors' evaluation and treatment offered is presented for each type.

Reflex effects of vibration in patients with spinal cord lesions

The vibration reflex was studied in 49 patients with traumatic spinal cord lesions. It was elicited in all patients, even after presumably complete division of the cord. The vibration relfex consisted of a short-latency, brief outburst of phasic activity of motor units, followed by rapidly decreasing phasic component and a later slowly declining tonic component. When periods of vibration were repeated at short intervals of 2 to 10 seconds, the responses showed an approximately exponential decline, although the beginning of each subsequent response was always larger than the end of the preceding response. A large part of this decline can be characterized as a habituation of the vibration reflex. In comparison with the vibration reflex in normal subjects, the phasic component was increased and the tonic one reduced. The tonic component was especially susceptible to potentiation and dishabituation by voluntary effort to contract the vibrated muscle, even in some patients with no other evidence that the lesion was incomplete. We suggest that the tonic component of the human vibration reflex depends, at least in part, on segmental interneurons and their descending spinal pathways, while the phasic component depends mainly on the excitability level of spinal motoneurons.