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Background The presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in human semen and its role in virus contagion and semen quality after recovery from coronavirus disease 2019 (COVID-19) is still unclear. Recent reports evidence that, after SARS-CoV-2 infection, male reproductive function and semen quality may be damaged. Aim To evaluate the semen parameters and inflammation of sexually active men following recovery from SARS-CoV-2 infection at 1 month and 3 months follow-up after the second negative nasopharyngeal swab. Materials and methods A prospective cross-sectional study on sexually active men recovered from SARS-CoV-2 infection was performed. For previously hospitalized COVID-19 patients, data on serum inflammatory markers were retrospectively collected. One month after the second SARS-CoV-2 negative nasopharyngeal swab and 3 months later, four biological fluid samples, namely saliva, pre-ejaculation urine, semen, and post-ejaculation urine, were collected. The occurrence of SARS-CoV-2 RNA in the specimen was evaluated in all the biological fluids collected by RT-PCR. Female partners were retested if any specimen was found to be SARS-CoV-2 positive. Semen parameters were evaluated according to the World Health Organization manual edition V. Furthermore, semen inflammation was assessed by quantification of semen leukocytes and interleukin-8 (IL-8) levels and evaluation of a panel of sperm cytokine levels by a two-step ELISA method. Results A total of 43 men were enrolled in the study. Three patients (7%) tested positive for at least one sample (one saliva; one pre-ejaculation urine; one semen and one post-ejaculation urine), so the next day new nasopharyngeal swabs were collected. The results from these 3 patients and their partners were all negative for SARS-CoV-2. At 1-month follow-up, 25% of the men with recent SARS-Cov-2 infections and proven healing were oligo-cryptoazoospermic, despite the absence of virus RNA in semen. Of the 11 men with semen impairment, 8 were azoospermic and 3 were oligospermic. Serum inflammatory markers (procalcitonin and C-reactive protein) were analyzed in previously hospitalized patients both at admission and at peak of infection. Levels at admission were statistically significantly higher in patients resulting in crypto-azoospermic with respect to those resulting in normozoospermic (p = 0.05; p = 0.03 and p = 0.02, respectively) after healing. Oligo-crypto-azoospermia was significantly related to COVID-19 severity (P A total of 33 patients (76.7%) showed pathological levels of IL-8 in semen. Interleukin-1β and tumor necrosis factor-α levels were significantly negatively related to sperm total number and concentration, whereas interleukin-4 was correlated with sperm motility. At 3-months follow-up, 8/10 men with semen impairment showed an overall increase of semen parameters compared to levels assessed after 1 month. Of the 4 crypto-/azoo-spermic men 1 month after healing, 2 resulted oligozoospermic, 1 normozoospermic and only 1 remained azoospermic. Two of the 3 oligozoospermic men turned normozoozpermic. Semen cytokine levels remained elevated after 3 months, except for IL-6. Discussion and conclusion SARS-CoV-2 can be detected in saliva, urine, and semen in a small percentage of men who recovered from COVID-19. 25% of men who recovered from COVID-19 demonstrated oligo-crypto-azoospermia. Negative correlations between interleukin-1β and tumor necrosis factor-α and sperm number and the overall high levels of semen cytokines indicate a potential detrimental role of SARS-CoV-2 driven inflammation on spermatogenesis. An overall tendency to an improvement of semen parameters was found although a genital tract inflammatory condition appears to persist at least 3 months after COVID-19 recovery. Despite the low number of enrolled patients may limit the statistical power of study and the fact that the previous semen quality of these men was unknown, our results indicate that male of reproductive age recovering from COVID-19 deserve accurate follow-up for their fertility status.

Natural products and their structural analogues have historically made a major contribution to pharmacotherapy, especially for cancer and infectious diseases. Nevertheless, natural products also present challenges for drug discovery, such as technical barriers to screening, isolation, characterization and optimization, which contributed to a decline in their pursuit by the pharmaceutical industry from the 1990s onwards. In recent years, several technological and scientific developments — including improved analytical tools, genome mining and engineering strategies, and microbial culturing advances — are addressing such challenges and opening up new opportunities. Consequently, interest in natural products as drug leads is being revitalized, particularly for tackling antimicrobial resistance. Here, we summarize recent technological developments that are enabling natural product-based drug discovery, highlight selected applications and discuss key opportunities. © 2021, Springer Nature Limited.

The search for more efficient machines leads to the reduction of friction in the lubricated contacts. One of the ways of achieving this goal is by texturing the surface of the contact. Much has been learned from textures imposed to the bearing casing or pads (static part of the lubricated contact), but there is still a gap in the knowledge of textured journals (moving part of the contact) and their resultant effects on the performance of the bearing. In this work, we present the experimental analysis of a journal bearing whose journal is textured with four different patterns: chevron, saw tooth, oblong dimple, and aligned dimple. Such patterns were imposed to the surface of the journal by the pattern grinding technology. We analyze the resultant eccentricity, attitude angle, and the driving torque of the journal for different operating conditions of the bearing (different Sommerfeld numbers). The obtained results show that the chevron pattern and the oblong dimple pattern present the biggest effects on the studied parameters. Such effect can be either positive or negative depending on the direction of motion of the pattern in the bearing (for unsymmetrical patterns). The aligned dimple texture did not present any significant effect on the bearing performance in comparison to the untextured case.

Water soluble LiFePO 4 inks for lithium ion battery cathodes were prepared and characterized. The pH versus aging time plot shows that stable inks have pH values around 9.13. Inductively Coupled Plasma (ICP) and X-ray Diffraction (XRD) results indicate that impurities are generated as the pH reaches its stable value. Electrical conductivity measurements however suggest that non-electrochemically active impurities lower the electrical conductivity of LiFePO 4 . A LiFePO 4 particle size change due to different binder adsorption mechanisms on the carbon surface is caused by changes in ion concentration which is determined by the initial pH values. Electrodes are fabricated by inkjet printing using ink prepared with an initial pH of 9.13 on two current collectors (aluminum foil and carbon nanotube paper (CNT paper)). A clear boundary between the aluminum current collector and electrode materials was observed using Scanning Electron Microscopy (SEM), which is possibly caused by the reaction between the alkaline dispersing solvent and the Al foil. XRD results also suggest the existence of impurities like LiAlO 2 and AlPO 4 after inkjet printing. Despite the uniform morphology of the electrode, electrochemical performance is still poor due to the impurities between the Al current collector and active materials. In contrast, a strong connects between active materials and CNT paper was confirmed by SEM. Battery with CNT paper current collector exhibited better electrochemical performance than Al current collector. This indicates that CNT paper is an alternative to the Al-foil current collector for LiFePO 4 aqueous based ink.

This work reports a complete characterization of buriti oil. Physicochemical properties were determined according to AOCS methodologies and thermophysical properties were measured using a controlled stress rheometer and a digital electronic density meter. β-carotene and tocopherol contents were obtained using HPLC systems. Fatty acids and acylglycerol classes were determined using GC and HPSEC systems, respectively, while triacylglycerol composition was estimated using the software PrOleos. Thermal behavior (crystallization and melting) was analyzed using a DSC. The results attested high levels of total carotenoids with β-carotene as the major one; total tocopherols contained α- and β-tocopherols which accounted for 91% of the total; and monounsaturated fatty acids were mainly represented by oleic acid. The results showed close agreement between density and viscosity of buriti and olive oils. The crystallization and melting peaks occurred at -43.06 °C and -2.73 °C, respectively. These properties enable Buriti oil to be recommended as an excellent alternative for enriching foods with bioactive compounds. En este trabajo realiza una completa caracterización del aceite de buriti. Las propiedades fisicoquímicas se llevaron a cabo de acuerdo con las metodologías AOCS y se midieron las propiedades termo-físicas usando un reómetro de esfuerzo controlado y un medidor de densidad electrónico digital. Se obtuvieron los contenidos de β-caroteno y tocoferol utilizando HPLC. Los ácidos grasos y las diferentes clases de acilgliceroles se determinaron utilizando GC y HPSEC, respectivamente, mientras que la composición de triacilglicéridos se estimó utilizando el software PrOleos. El comportamiento térmico (cristalización y fusión) se analizó utilizando un DSC. Los resultados ponen de manifiesto altos niveles de carotenoides totales con β-caroteno como mayoritario, tocoferoles totales, con α- y β-tocoferoles que representan el 91% del total, y ácidos grasos monoinsaturados representados principalmente por ácido oleico. Hay una estrecha relación entre la densidad y la viscosidad del aceite de buriti y las de los aceites de oliva. Los picos de cristalización y de fusión se dan a -43,06 °C y -2,73 °C, respectivamente. Estas propiedades permiten que el aceite de Buriti sea recomendado como una excelente alternativa para enriquecer alimentos con compuestos bioactivos.

SHG microscopy was successfully used to characterize the orientation of sutural lamellae within corneal samples by means of an epi-detection scheme. Sutural lamellae are located in the first 30 ?m of the stromal layer below Bowman's membrane; they affect the mechanical properties of the cornea and are responsible of the overall corneal stiffness. This stromal layer is particularly interesting for diagnosing and following-up keratoconus, an eye disorder that features a reduced stiffness of the cornea and its consequent pathological deformation. The methodology was tested by acquiring image stacks of the central portion of the cornea in ex vivo samples of healthy corneas, keratoconic corneas and keratoconic corneas treated with cross-linking (CXL), a treatment aimed at hindering the progression of keratoconus. The samples were imaged and characterized based on forward/backward SHG ratio, finding a different ratio in keratoconus with respect to both the healthy cornea and cross-linked keratoconus. The inclination of corneal sutural lamellae was then characterized by means of a three-dimensional correlation analysis on SHG images, acquired using a backward detection geometry. Such method provided good discrimination capabilities, demonstrating that this approach can be used not only for diagnosing keratoconus in a very early stage, but also for performing treatment follow-up on cross-linked corneas.

The Terahertz Time Domain Reflection Spectroscopy (THz-TDS) method of paint layer diagnostics is a non-contact electromagnetic technique analogous to pulsed-ultrasound with the added capability of spectroscopic characterization. The THz-TDS sensor emits a near-single cycle electromagnetic pulse with a bandwidth from 0.1 to 3 THz. This wide bandwidth pulse is focused on the coating, and echo pulses are generated from each interface (air-coating, layer-layer, coating-substrate). In this paper, the THz-TDS method is applied to specialty aircraft coatings. The THz-TDS method is able to penetrate the whole coating stack and sample the properties of each layer. Because the reflected pulses from individual layers typically overlap in time, the complex permittivity function and thickness of each layer is determined by a best fit of the measured reflection (either in time or frequency domain) to a layered model of the paint. The THz- TDS method is applied to specialty coatings prior to and during accelerated aging on a series of test coupons. The coupons are also examined during aging using ATR (attenuated total reflectance)-FTIR spectroscopy, Raman scattering spectroscopy, and Scanning Electron Microscopy (SEM) to ascertain, quantify, and understand the breakdown mechanisms of the coatings. In addition, the same samples are characterized using THz-TDS techniques to determine if the THz-TDS method can be utilized as a non-destructive evaluation technique to sense degradation of the coatings. Our results suggest that the degradation mechanism begins in the top coat layer. In this layer, 254 nm UV illumination in combination with the presence of moisture works partially with oxides as catalysts to decompose the polymer matrix thereby creating porosity in the top coat layer. Since the catalytic effect is partial, loss of the oxides by chemical reaction can also occur. As the topcoat layer becomes more porous, it allows water vapor to permeate the topcoat layer and interact with the rain erosion layer via carbonization of the polymer matrix in the rain erosion layer. The presence of the salt accelerates the pitting degradation. The goal of this paper is to determine if THz-TDS can be used to sense degradation of the coating.

Malignant pleural mesothelioma is a fatal malignancy linked to asbestos exposure. The main challenge for mesothelioma treatment is to go beyond the drug resistance, in particular against cisplatin (CDDP), one of the most used chemotherapeutic drug. 3-O-methylfunicone (OMF) is a metabolite produced by the fungus Penicillium pinophilum; its antiproliferative properties have been previously studied in vitro. Particularly, OMF is able to inhibit mesothelioma cell motility. To improve the effects of CDDP by-passing the resistance of mesothelioma cells to this drug, in the present study we investigated the combined treatment of OMF with CDDP respectively in an established mesothelioma cell line (NCI) and primary mesothelioma cells (Mest). As compared to the effect of single treatments, the combination of OMF and CDDP resulted in a stronger inhibition of NCI and Mest cell proliferation. OMF combination with CDDP was also able to affect the migratory ability of NCI and Mest cells by down-regulating αv and β5 expression and reducing metalloproteinase 2 (MMP-2) production. In addition, this association was effective in modulating VEGF gene expression. This finding highlights the possibility to use OMF and CDDP together to regulate angiogenesis and tumour progression in mesothelioma.

Asphondylia spp. (Diptera: Cecidomyiidae) are known for inducing gall formation on many diverse plants in both wild and agricultural contexts. The species Asphondylia serpylli is herewith reported for the first time on thyme (Thymus vulgaris) cropped in Poland. The associated fungus has been identified as Botryosphaeria dothidea, representing its first record from cecidomyiid galls on a species of Lamiaceae. Moreover, a short account is given on the parasitoid species active in this particular ecological context. These findings point out the basic role of B. dothidea in the organization of these three-component biotic systems regardless of the varied assortments between the midge species and their host plant.

Keratoconus is an eye disorder that features a reduced stiffness of the cornea and its consequent pathological deformation. Cross-Linking (CXL) treatment has proven useful in hindering the progression of keratoconus, offering a minimally-invasive alternative to corneal surgical transplantation. In this study, the biomechanical characteristics of a human keratoconic cornea were clinically examined in vivo soon before keratoplasty, and the morphological alterations of the collagen scaffold in the same cornea were examined ex vivo by means of Second-Harmonic Generation (SHG) microscopy. A healthy cornea and a CXL-treated keratoconus were compared. In particular, the lamellar organization in the three corneal samples was characterized in different stromal layers by detecting both forward- and backwardscattered SHG signal and then considering the forward/backward (F/B) ratio as parameter. The F/B ratio was used to characterize the morphological organization of collagen lamellae within different stromal layers, finding an increased disorder at the level of Bowman's membrane, opposed to a more regular organization within deeper stromal layers in all the examined samples. The organization of collagen lamellae in CXL-treated keratoconic samples was similar to that one found in healthy corneas, demonstrating that the CXL is able to rearrange the collagen scaffold and partially recover the properties of a healthy condition. The obtained results are in agreement with previous results obtained in studies aimed at monitoring the organization of fibrillar collagen using F/B SHG ratio. In conclusion, the proposed method might be useful for both diagnosing keratoconus as well as for monitoring the effects of the CXL treatment.

SHG microscopy was successfully used to characterize the orientation of sutural lamellae within corneal samples by means of an epi-detection scheme. In particular, the attention was focused on the organization and orientation of corneal collagen lamellae in the first 30 mu m of the stromal layer below Bowman's membrane. In fact, it is thought that the irregular orientation of these specific lamellae, an in particular the existence of so-called sutural lamellae, affects the mechanical properties of the cornea and is responsible of the overall corneal stiffness. The methodology was tested by acquiring image stacks of the central portion of the cornea in ex vivo samples of healthy corneas, keratoconic corneas and keratoconic corneas treated with cross-linking. These samples represent a good benchmark for testing the methodology, considering that keratoconus is an ophthalmic disease in which the cornea loses its stiffness and acquires an abnormal conical shape because of a different organization of sutural lamellae. The samples were first imaged and characterized on the basis of forward/backward SHG ratio, finding a different ratio in keratoconus with respect to both the healthy cornea and cross-linked keratoconus. The inclination of corneal sutural lamellae was then characterized by means of a three-dimensional correlation analysis on SHG images, acquired using a backward detection geometry. Such method provided good discrimination capabilities, demonstrating that this approach can be used not only for diagnosing keratoconus in a very early stage, but also for performing treatment follow-up on cross-linked corneas.

SHG image acquired with sagittal optical sectioning (A) of a healthy cornea and (B) of a keratoconic cornea. Scale bars: 30 μm. Keratoconus is an eye disorder that causes the cornea to take an abnormal conical shape, thus impairing its refractive functions and causing blindness. The late diagnosis of keratoconus is among the principal reasons for corneal surgical transplantation. This pathology is characterized by a reduced corneal stiffness in the region immediately below Bowman's membrane, probably due to a different lamellar organization, as suggested by previous studies. Here, the lamellar organization in this corneal region is characterized in three dimensions by means of second-harmonic generation (SHG) microscopy. In particular, a method based on a three-dimensional correlation analysis allows to probe the orientation of sutural lamellae close to the Bowman's membrane, finding statistical differences between healthy and keratoconic samples. This method is demonstrated also in combination with an epi-detection scheme, paving the way for a potential clinical ophthalmic application of SHG microscopy for the early diagnosis of keratoconus.

Background Although lumbar zygapophyseal joint synovial cysts are fairly well recognized, they are an uncommon cause of lumbosacral radicular pain. Nonoperative treatments include percutaneous aspiration of the cysts under computed tomography or fluoroscopic guidance with a subsequent corticosteroid injection. However, there are mixed results in terms of long-term outcomes and cyst reoccurrence. This study prospectively evaluates percutaneous ruptures of zygapophyseal joint (Z-joint) synovial cysts for the treatment of lumbosacral radicular pain. Objectives Primary: To determine whether percutaneous rupture of symptomatic Z-joint synovial cysts leads to sustained improvements in radicular pain and function. Secondary: To assess the rates of cyst recurrence and progression to surgical intervention following percutaneous rupture of symptomatic Z-joint synovial cysts. Design Prospective cohort study. Setting Outpatient academic spine practice. Participants Adults with primary radicular pain due to a facet synovial cyst. Methods Participants underwent fluoroscopically guided percutaneous Z-joint synovial cyst ruptures under standard-of-care practice. Data on pain, physical function, satisfaction, and progression to surgery were collected at 2 weeks, 6 weeks, 3 months, 6 months, and 1 year after rupture. An intention-to-treat analysis was used for assessment of patient-reported outcome measures. Main Outcome Measures The Numerical Rating Scale, Oswestry Disability Index, and modified North American Spine Society questionnaires were used to measure pain, function, and satisfaction with the procedure, respectively. Results Thirty-five participants were included in the study, and data were analyzed by an independent researcher. Statistically significant changes in Oswestry Disability Index were reported at 2 weeks, 3 months, and 1 year postintervention ( P = .034, .040, and .039, respectively). A statistically and clinically significant relief of current pain was reported at 2 weeks ( P = .025) and 6 weeks ( P = .014) with respect to baseline. Patients showed significant improvements for best pain at 6 weeks with respect to baseline ( P = .031). Patients' worst pain showed the greatest amount of improvement with clinically meaningful changes at all time points compared with baseline. Patient-reported satisfaction was found nearly 70% of the time at all time points. Forty percent (14/35) of participants required repeat cyst rupture, and 31% (11/35) required surgical interventions. Conclusions There were statistically and clinically significant improvements in pain and function after percutaneous rupture of Z-joint synovial cysts. In addition, the outcomes support previous retrospective studies indicating that approximately 40% of patients will need surgery. This study provides further research to determine the utility of this procedure and to precisely define a subset of ideal candidates. Level of Evidence Level II.

Keratoconus is an ophthalmic disease in which the cornea acquires an abnormal conical shape that prevents the correct focusing on the retina, causing visual impairment. The late diagnosis of keratoconus is among the principal causes of corneal transplantation surgery. In this study, we characterize the morphology of keratoconic corneas by means of the correlation of SHG images, finding that keratoconus can be diagnosed by analyzing the inclination of lamellae below Bowman’s membrane. In addition, imaging performed with both sagittal and “en face” geometry demonstrated that this morphological features can be highlighted both ex vivo and in vivo.

Keratoconus is an ophthalmic disease in which the cornea acquires an abnormal conical shape that prevents the correct focusing on the retina, causing visual impairment. The late diagnosis of keratoconus is among the principal causes of corneal transplantation surgery. In several previous studies, a different organization sutural lamellae was observed in keratoconic corneas compared to healthy corneas. This study is intended to investigate this anomaly by means of Second Harmonic Generation (SHG) microscopy, using an optical scheme relevant for clinical applications. In particular, we propose a method based on 3D correlation of SHG image stacks, able to appreciate statistical differences in the orientation distribution of sutural lamellae between healthy and keratoconic corneas. The proposed method offers the potential for diagnosing keratoconus in an early stage.

The present study was designed to reveal possible differences in the degree of frusemide response and retention index between essential and renovascular hypertension

Differential scanning calorimetry (DSC) was used to determine phase transitions of freeze-dried plums. Samples at low and intermediate moisture contents, were conditioned by adsorption at various water activities (0.11≤aw≤0.90) at 25°C, whereas in the high moisture content region (aw>0.90) samples were obtained by direct water addition, with the resulting sorption isotherm being well described by the Guggenheim-Anderson-deBoer (GAB) model. Freeze-dried samples of separated plum skin and pulp were also analysed. At aw≤0.75, two glass transitions were visible, with the glass transition temperature (Tg) decreasing with increasing aw due to the water plasticising effect. The first Tg was attributed to the matrix formed by sugars and water. The second one, less visible and less plasticised by water, was probably due to macromolecules of the fruit pulp. The Gordon-Taylor model represented satisfactorily the matrix glass transition curve for aw≤0.90. In the higher moisture content range Tg remained practically constant around Tg′ (−57.5°C). Analysis of the glass transition curve and the sorption isotherm indicated that stability at a temperature of 25°C, would be attained by freeze dried plum at a water activity of 0.04, corresponding to a moisture content of 12.9% (dry basis).

Background/aims: Many cytokines are involved in the pathogenesis of retinal proliferative diseases, but none has been shown to be related to a specific disorder. The aim of this study was to provide a selective marker of diabetes induced proliferative retinopathies. Methods: 10 vitreous samples from 10 subjects affected by quiescent proliferative diabetic retinopathy (PDR), 20 vitreous samples from 20 subjects affected by active PDR, and 15 samples from 15 patients with proliferative vitreoretinopathy (PVR) were studied. Samples from 18 patients with a macular hole (n = 8) or pucker (n = 10) served as controls. Vitreous samples were obtained via pars plana vitrectomy. The polyamines spermidine, putrescine, and spermine, vascular endothelial growth factor (VEGF), interleukin 8 (IL-8), and transforming growth factor 1β (TGF-1β) were measured by high performance liquid chromatography (HPLC) and enzyme linked immunosorbent assay (ELISA), and the correlation coefficients between the vitreous polyamine content and VEGF, IL-8, and TGF-1β levels were determined. Results: Spermidine and putrescine were expressed in normal vitreous, but spermine was not detectable. In all the test groups spermidine was 3–4 times higher than in control vitreous and putrescine was similarly lower. The spermine content was up to 15 times higher only in vitreous from patients affected by PDR. Correlation coefficients showed that the spermidine and putrescine level variations correlated with the VEGF and IL-8 content in the active PDR and PVR groups, but not in those with quiescent PDR patients, while spermine was correlated to these cytokines in PDR, but not in PVR groups. Conclusions: These data suggest a significant role for spermidine and putrescine as markers of proliferative diseases of the retina. The increase in spermine, restricted to diabetic states, may indicate that this polyamine is a unique and specific index of PDR.

Subanaesthetic doses of the N-methyl-D-aspartate (NMDA) antagonist ketamine have been shown to determine a dual modulating effect on glutamatergic transmission in experimental animals, blocking NMDA receptor activity and enhancing non-NMDA transmission through an increase in the release of endogenous glutamate. Little is known about the effects of ketamine on the excitability of the human central nervous system. The effects of subanaesthetic, graded incremental doses of ketamine (0.01, 0.02 and 0.04 mg kg-1 min-1, I.V.) on the excitability of cortical networks of the human motor cortex were examined with a range of transcranial magnetic and electric stimulation protocols in seven normal subjects. Administration of ketamine at increasing doses produced a progressive reduction in the mean resting motor threshold (RMT) (F(3, 18) = 22.33, P0.001) and active motor threshold (AMT) (F(3, 18) = 12.17, P0.001). Before ketamine administration, mean RMT +/- S.D. was 49 +/- 3.3 % of maximum stimulator output and at the highest infusion level it was 42.6 +/- 2.6 % (P0.001). Before ketamine administration, AMT +/- S.D. was 38 +/- 3.3 % of maximum stimulator output and at the highest infusion level it was 33 +/- 4.4 % (P0.002). Ketamine also led to an increase in the amplitude of EMG responses evoked by magnetic stimulation at rest; this increase was a function of ketamine dosage (F(3, 18) = 5.29, P = 0.009). In contrast to responses evoked by magnetic stimulation, responses evoked by electric stimulation were not modified by ketamine. The differential effect of ketamine on responses evoked by magnetic and electric stimulation demonstrates that subanaesthetic doses of ketamine enhance the recruitment of excitatory cortical networks in motor cortex. Transcranial magnetic stimulation produces a high-frequency repetitive discharge of pyramidal neurones and for this reason probably depends mostly on short-lasting AMPA transmission. An increase in this transmission might facilitate the repetitive discharge of pyramidal cells after transcranial magnetic stimulation which, in turn, results in larger motor responses and lower thresholds. We suggest that the enhancement of human motor cortex excitability to transcranial magnetic stimulation is the effect of an increase in glutamatergic transmission at non-NMDA receptors similar to that described in experimental studies.