Atomic-Scale Variations of the Mechanical Response of 2D Materials Detected by Noncontact Atomic Force Microscopy.

We show that noncontact atomic force microscopy (AFM) is sensitive to the local stiffness in the atomic-scale limit on weakly coupled 2D materials, as graphene on metals. Our large amplitude AFM topography and dissipation images under ultrahigh vacuum and low temperature resolve the atomic and moiré patterns in graphene on Pt(111), despite its extremely low geometric corrugation. The imaging mechanisms are identified with a multiscale model based on density-functional theory calculations, where the energy cost of global and local deformations of graphene competes with short-range chemical and long-range van der Waals interactions. Atomic contrast is related with short-range tip-sample interactions, while the dissipation can be understood in terms of global deformations in the weakly coupled graphene layer. Remarkably, the observed moiré modulation is linked with the subtle variations of the local interplanar graphene-substrate interaction, opening a new route to explore the local mechanical properties of 2D materials at the atomic scale.

Vipericidins: a novel family of cathelicidin-related peptides from the venom gland of South American pit vipers.

Cathelicidins are phylogenetically ancient, pleiotropic host defense peptides-also called antimicrobial peptides (AMPs)-expressed in numerous life forms for innate immunity. Since even the jawless hagfish expresses cathelicidins, these genetically encoded host defense peptides are at least 400 million years old. More recently, cathelicidins with varying antipathogenic activities and cytotoxicities were discovered in the venoms of poisonous snakes; for these creatures, cathelicidins may also serve as weapons against prey and predators, as well as for innate immunity. We report herein the expression of orthologous cathelicidin genes in the venoms of four different South American pit vipers (Bothrops atrox, Bothrops lutzi, Crotalus durissus terrificus, and Lachesis muta rhombeata)-distant relatives of Asian cobras and kraits, previously shown to express cathelicidins-and an elapid, Pseudonaja textilis. We identified six novel, genetically encoded peptides: four from pit vipers, collectively named vipericidins, and two from the elapid. These new venom-derived cathelicidins exhibited potent killing activity against a number of bacterial strains (S. pyogenes, A. baumannii, E. faecalis, S. aureus, E. coli, K. pneumoniae, and P. aeruginosa), mostly with relatively less potent hemolysis, indicating their possible usefulness as lead structures for the development of new anti-infective agents. It is worth noting that these South American snake venom peptides are comparable in cytotoxicity (e.g., hemolysis) to human cathelicidin LL-37, and much lower than other membrane-active peptides such as mastoparan 7 and melittin from bee venom. Overall, the excellent bactericidal profile of vipericidins suggests they are a promising template for the development of broad-spectrum peptide antibiotics.

Influence of conjugation chemistry and B epitope orientation on the immune response of branched peptide antigens.

Multimeric presentation, a well-proven way of enhancing peptide immunogenicity, has found substantial application in synthetic vaccine design. We have reported that a combination of four copies of a B-cell epitope with one of a T-cell epitope in a single branched construct results in a peptide vaccine conferring total protection against foot-and-mouth disease virus in swine, a natural host (Cubillos et al. (2008) J. Virol. 82, 7223-7230). More recently, a downsized version of this prototype with only two copies of the B epitope has proven as effective as the tetravalent one in mice. Here we evaluate three approaches to bivalent platforms of this latter type, involving different chemistries for the conjugation of two B epitope peptides to a branching T epitope. Comparison of classical thioether, "reverse" thioether (Monsó et al. (2012) Org. Biomol. Chem. 10, 3116-3121) and thiol-ene conjugation chemistries in terms of synthetic efficiency clearly singles out the latter, maleimide-based strategy as most advantageous. We also examine how minor structural differences among the conjugates--including the N- or C-terminal attachment of the B epitope to the branching T epitope--bear on the immunogenicity of these vaccine candidates, with the maleimide-based conjugate again emerging as the most successful.

Visualization of π-hole in molecules by means of Kelvin probe force microscopy.

Submolecular charge distribution significantly affects the physical-chemical properties of molecules and their mutual interaction. One example is the presence of a π-electron-deficient cavity in halogen-substituted polyaromatic hydrocarbon compounds, the so-called π-holes, the existence of which was predicted theoretically, but the direct experimental observation is still missing. Here we present the resolution of the π-hole on a single molecule using the Kelvin probe force microscopy, which supports the theoretical prediction of its existence. In addition, experimental measurements supported by theoretical calculations show the importance of π-holes in the process of adsorption of molecules on solid-state surfaces. This study expands our understanding of the π-hole systems and, at the same time, opens up possibilities for studying the influence of submolecular charge distribution on the chemical properties of molecules and their mutual interaction.

Efficacy of cecropin A-melittin peptides on a sepsis model of infection by pan-resistant Acinetobacter baumannii.

Pan-resistant Acinetobacter baumannii have prompted the search for therapeutic alternatives. We evaluate the efficacy of four cecropin A-melittin hybrid peptides (CA-M) in vivo. Toxicity was determined in mouse erythrocytes and in mice (lethal dose parameters were LD(0), LD(50), LD(100)). Protective dose 50 (PD(50)) was determined by inoculating groups of ten mice with the minimal lethal dose of A. baumannii (BMLD) and treating with doses of each CA-M from 0.5 mg/kg to LD(0). The activity of CA-Ms against A. baumannii was assessed in a peritoneal sepsis model. Mice were sacrificed at 0 and 1, 3, 5, and 7-h post-treatment. Spleen and peritoneal fluid bacterial concentrations were measured. CA(1-8)M(1-18) was the less haemolytic on mouse erythrocytes. LD(0) (mg/kg) was 32 for CA(1-8)M(1-18), CA(1-7)M(2-9), and Oct-CA(1-7)M(2-9), and 16 for CA(1-7)M(5-9). PD(50) was not achieved with non-toxic doses (≤ LD(0)). In the sepsis model, all CA-Ms were bacteriostatic in spleen, and decreased bacterial concentration (p < 0.05) in peritoneal fluid, at 1-h post-treatment; at later times, bacterial regrowth was observed in peritoneal fluid. CA-Ms showed local short-term efficacy in the peritoneal sepsis model caused by pan-resistant Acinetobacter baumannii.

Real-space imaging of anisotropic charge of σ-hole by means of Kelvin probe force microscopy.

An anisotropic charge distribution on individual atoms, such as σ-holes, may strongly affect the material and structural properties of systems. However, the spatial resolution of such anisotropic charge distributions on an atom represents a long-standing experimental challenge. In particular, the existence of the σ-hole on halogen atoms has been demonstrated only indirectly through the determination of the crystal structures of organic molecules containing halogens or with theoretical calculations, consequently calling for its direct experimental visualization. We show that Kelvin probe force microscopy with a properly functionalized probe can image the anisotropic charge of the σ-hole and the quadrupolar charge of a carbon monoxide molecule. This opens a new way to characterize biological and chemical systems in which anisotropic atomic charges play a decisive role.

[Prevalence of cardiovascular disease in uraemia and relevance of cardiovascular risk factors]. / Prevalencia de enfermedad cardiovascular en la uremia y relevancia de los factores de riesgo cardiovascular.

AIM: To evaluate the prevalence of cardiovascular disease (CVD) and its association with cardiovascular risk factors, as well as their control in end-stage renal disease (ESRD) patients under maintenance hemodialysis (HD). PATIENTS AND METHODS: A total of 265 patients with ESRD on maintenance HD from a University Hospital and 4 dialysis units were included in this multicenter and cross-sectional study that analyzed the prevalence of CVD and the possible association with classic and new cardiovascular risk factors. Usual biochemical and haemathological parameters were analyzed, as well as plasma levels of homocysteine, troponin-I, BNP, lipoprotein(a), C reactive protein, IL-6, fibrinogen, asymmetrical dimethylarginine (ADMA), advanced oxidation protein products (AOPP), malondialdehyde, adiponectin, osteoprotegerin, and fetuin. In a subset of patients an echocardiography and carotid artery Doppler echography were also performed. RESULTS: The prevalence of CVD was 52.8%. Factors positively associated with prevalent CVD were age, BMI, left ventricular hypertrophy, hypertension, dyslipidemia and diabetes mellitus, dialysis vintage, Charlson s comorbility index, levels of fibrinogen, osteoprotegerin, BNP and CRP, as well as carotid intima-media thickness, left ventricular mass and pulse pressure. Factors negatively associated with prevalent CVD were: previous renal transplant, ejection fraction or levels of LDL-c and phosphorous. In the multivariate analysis dyslipidemia, left ventricular hypertrophy, age and LDL-c (negatively) were associated with CVD. CONCLUSIONS: In HD patients the prevalence of CVD is high and is associated with the presence of cardiovascular risk factors and subclinical CVD.

Experimental study of the application of a new bone cement loaded with broad spectrum antibiotics for the treatment of bone infection. / Estudio experimental de la aplicación de un nuevo cemento óseo cargado con antibióticos de amplio espectro para el tratamiento de la infección ósea.

OBJECTIVES: To evaluate the in vivo behaviour of a new bone cement loaded with antibiotics, in a rabbit bone infection model. MATERIAL AND METHODS: Sixteen New Zealand rabbits divided into 4 groups were used, depending on the cement (commercial or experimental) and the antibiotic (vancomycin or linezolid) used to control a bone infection caused by Staphylococcus aureus. The commercial cement is Palacos® R and the experimental cement has been achieved by adding PLGA to the solid phase of Palacos® R cement. A novel histological staging method based on bone histoarchitecture has been used. This staging allows us a global vision of bone repair capacity, in the presence of modified cement, and also allows us to correlate the damage generated with the functionality of the tissue. RESULTS: The degree of bone destructuration found depended on the type of cement and antibiotic, and was higher in the groups with commercial cement than in the experimental group (P<.01) and in the groups with linezolid with respect to vancomycin (P=.04) The percentage of macrophages varied exclusively depending on the antibiotic used, and was higher in the vancomycin groups (P=.04). DISCUSSION: The development of new formulations of bone cement that release more, and more prolonged, new generation antibiotics such as linezolid, present an in vivo behaviour superior to commercial cement, respecting the bone structure. This behaviour would have a clinical implication in fighting infections by increasingly resistant germs in the treatment of prosthetic infection.

Development of advanced biantibiotic loaded bone cement spacers for arthroplasty associated infections.

The incidence increase of infections in patients with hip or knee implants with resistant pathogens (mainly some S. coagulase-negative and gram positive bacteria) demands advanced antibiotic loaded formulations. In this paper, we report the design of new biantibiotic acrylic bone cements for in situ delivery. They include a last generation antibiotic (daptomycin or linezolid) in combination with vancomycin and are performed based on a novel modification of the Palacos R® acrylic bone cement, which is based on two components, a liquid (methyl methacrylate) and a solid (polymeric phase). Hence, the solid component of the experimental formulations include 45wt% of microparticles of poly(D,L-lactic-co-glycolic) acid, 55wt% of poly(methyl methacrylate) beads and supplements (10wt-% each) of antibiotics. These formulations provide a selective and excellent control of the local release of antibiotics during a long time period (up to 2 months), avoiding systemic dissemination. The antimicrobial activity of the advanced spacers tested against S. aureus shows that single doses would be enough for the control of the infection. In vitro biocompatibility of cements on human osteoblasts is ensured. This paper is mainly focused on the preparation and characterization of cements and the studies of elution kinetics and bactericidal effects. Developed formulations are proposed as spacers for the treatment of infected arthroplasties, but also, they could be applied in other antibiotic devices to treat relevant bone-related infection diseases.

Single-view screening mammography: psychological, endocrine and immunological effects of recalling for a complete three-view examination.

To investigate influences of a recall due to inconclusive findings on screening mammography, 45 women were examined with psychological ('mood' and 'coping'), endocrine and immunological tests immediately after complete mammography (first interview), 2-3 days after the initial screening mammography, and 3 weeks after the women had been informed of normal findings (second interview). The mood score in the first interview was significantly lower than in the second. No differences were found in the endocrine and immunological tests. The recall for complete mammography provoked a significant short-term emotional reaction not reflected in changes in the endocrine and immune functions.

Adrenocortical and gonadal steroids during sleep deprivation.

Twelve healthy males were exposed to 48 hr of sleep deprivation under conditions of strictly controlled activity and of food and drink intake. During the experiment the subjects were isolated from external time cures, i.e. no daylight, clocks, etc. Plasma samples were obtained before and at the end of the vigil, as well as after 5 days of recovery. Samples were analyzed for adrenal and gonadal steroid hormones and for follicle-stimulating (FSH) and luteinizing hormones (LH). The levels of all unconjugated steroids studied (cortisol, 17-hydroxypregnenolone, 17-hydroxyprogesterone, androstenedione, dihydrotestosterone) were significantly lower at the end of the sleep deprivation period. Self-ratings of fatigue were significantly higher at the end of the deprivation period. After recovery, all values returned to base line. No changes were observed in the levels of FSH, LH, or most conjugated steroids. It was concluded that the results were not consistent with the view that sleep deprivation induces an emergency reaction with increased activation, but rather that it results in lower levels of both psychological and physiological activation.

Low sulpho-conjugated steroid hormone levels in systemic lupus erythematosus (SLE).

In a clinical study the blood levels of dehydroepiandrosterone sulphate (DHEAS), pregnenolone sulphate (5-PS), testosterone sulphate (TS) and their respective unconjugated steroids were measured in: 20 patients with systemic lupus erythematosus (SLE) who were receiving either no treatment (11 patients) or else treatment with chloroquine (9 patients), in some cases combined with non-steroidal anti-inflammatory drugs (NSAIDs); in 26 patients receiving corticosteroid (Prednisolone) treatment; and in healthy men and women. The patients not on corticosteroid exhibited substantially reduced DHEAS, 5-PS and TS levels (geom. mean: 2300 vs. normal 4300 nmol/l DHEAS; 200 vs. 320 nmol/l 5-PS; and 120 vs. 360 nmol/l TS; p less than 0.001), irrespective of the difference in sex, age or chloroquine treatment. The patients on corticosteroid treatment displayed a similar pattern of levels, but the reduction was much more marked than in the patients not on the steroid (geom. mean: 610 nmol/l DHEAS, 55 nmol/l 5-PS; and 35 nmol/l TS; p less than 0.001). No consistent changes were observed in the unconjugated steroid levels, although they were also reduced by the treatment with prednisolone. The data indicate that a deficiency in sulpho-conjugated steroids is a permanent feature of patients with SLE and that this is accentuated by the administration of corticosteroid derivatives. Further studies are needed to establish the pathophysiological significance of these findings.

Low blood and synovial fluid levels of sulpho-conjugated steroids in rheumatoid arthritis.

Using radioimmunoassays (RIA) we measured the concentrations of prolactin, cortisol, dehydroepiandrosterone sulphate (DHEAS), pregnenolone sulphate (5-PS) and testosterone sulphate (TS) in peripheral blood and synovial fluid (SF) from 50 patients with arthritis of the knee associated with different diagnoses. These included RA (25 cases); and psoriasis, ankylosing spondylitis, reactive arthritis, post-traumatic arthritis, unspecified polyarthritis, polyarthritis and sacroilitis, and regional enteritis (25 cases). Fifty-six healthy subjects (age 19 to 60 years) were used as controls. No significant difference was found between the blood prolactin levels in patients and controls. The mean levels of cortisol, 5-PS, DHEAS and TS were significantly reduced in the patients with RA (mean 133 vs 286 nmol/l cortisol, 26 vs 80 nmol/l 5-PS, 930 vs 3290 nmol/l DHEAS and 25 vs 40 nmol/l TS; p less than 0.001 for cortisol, 5-PS and DHEAS, and p less than 0.05 for TS). The reduction was more marked in the DHEAS levels in patients with positive rheumatoid factor (RF) reactivity. Patients with diagnoses other than RA had normal levels of the various steroids except patients on steroid treatment, who also exhibited reduced levels. The 5 hormones measured in the SF were found in relatively high concentrations, parallelling those in the blood. The ratios (SF/blood) varied from 0.66 for 5-PS to 1.1 for cortisol, and the correlation coefficients between 0.66 for 5-PS and 0.94 for DHEAS (p less than 0.001). Low blood and SF levels of sulpho-conjugated steroids, particularly DHEAS, are a permanent disorder in patients with RA and positive RF reactivity.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood and tissue dehydroepiandrosterone sulphate levels and their relationship to chronic inflammatory bowel disease.

OBJECTIVE: To evaluate the levels of dehydroepiandrosterone sulphate (DHEAS) in the blood and tissues of patients with inflammatory bowel disease (IBD). METHODS: DHEAS levels were measured by radioimmunoassay in blood from 112 patients with IBD: 46 with ulcerative colitis (UC) and 66 with Crohn's disease. The levels were compared with those in 80 healthy controls. In addition, DHEAS concentrations were measured in gut tissue from 40 patients (28 patients with IBD and 12 with other bowel disorders) who had undergone gut surgery. Correlation analyses were carried out between the blood and tissue levels of DHEAS. RESULTS: The mean levels of DHEAS in the blood were markedly lower in the two patient groups (1350 nmol/l in UC and 1850 nmol/l in Crohn's disease vs. 3300 nmol/l in controls; p < 0.001 and p < 0.01 respectively). A diminution below the confidence limits of the controls (< 2500 nmol/l) was found in 37 (79%) of the patients with UC and in 49 (74%) of those with Crohn's disease. The remainder had DHEAS levels within the normal range (> 2500 nmol/l). The overall mean DHEAS concentration in gut tissue was 226 nmol/kg. A significant correlation was found between levels in the blood and those in tissues (correlation coefficient = 0.469; p < 0.002). CONCLUSION: These data indicate that low blood DHEAS is a feature in a majority of patients with UC or Crohn's disease. The possibility that there is a functional relationship between low DHEAS levels and some of the pathophysiologic features of IBD needs to be investigated.

Blood dehydroepiandrosterone sulphate (DHEAS) levels in pemphigoid/pemphigus and psoriasis.

Serum dehydroepiandrosterone sulphate (DHEAS) levels and diagnostic autoantibody titers were measured in patients with pemphigoid/pemphigus [n = 46/4; 21 men and 29 women, 42 to 93 years of age (mean 79)]. Twenty-four patients were either on peroral Prednisolone (n = 11), or topical treatment with betamethasone (n = 13), and the other 26 were either receiving non-steroidal drugs or were untreated. Their DHEAS levels were compared to those of 20 patients with psoriasis, and to 23 patients with secondary osteoarthritis (OA). Assessing the patients by group, the mean DHEAS level was markedly lower in the pemphigoid/pemphigus than in the psoriasis and OA patients (geometric mean 600 vs. 2130 and 2100 nmol/l, respectively; p < 0.001). This difference was independent of steroid treatment. No correlation was found between the DHEAS levels and antibody titers. The low levels found in pemphigoid/pemphigus are concordant with those reported for systemic lupus erythematosus, rheumatoid arthritis and polymyalgia rheumatica/giant cell arteritis. DHEAS deficiency is a permanent feature in these autoimmune diseases, and may contribute to their etiology and/or pathophysiology.

Blood cortisol and dehydroepiandrosterone sulphate (DHEAS) levels and CD4 T cell counts in HIV infection.

OBJECTIVE: Blood cortisol and dehydroepiandrosterone sulphate (DHEAS) levels, and CD4 T cell counts were assessed in a group of 44 patients with HIV infection (17 asymptomatic and 27 symptomatic). The steroid levels were compared to those in 80 healthy subjects. RESULTS: The mean cortisol level did not differ between the HIV patients and controls. However, a broad variability existed among the patients; thus, asymptomatic HIV patients revealed a significantly higher mean level than the controls (348 nmol/l vs. 280 nmol/l; p < 0.01). Furthermore, 20 patients had levels above, 16 within, and 8 below the confidence limits of the cortisol levels in controls. This variability might reflect differences in adrenocortical responses to psychological stress and adaptive reactions among patients with HIV infection. The mean DHEAS was markedly lowered in the patient group (1450 nmol/l in patients vs. 3300 nmol/l in controls; p < 0.001). A decrease below the confidence limits of the controls existed in 41 (93%) of the 44 patients. A significant correlation was also found between the low DHEAS levels and low CD4 T cell counts in the patients (p < 0.01), while no such correlation existed for cortisol. CONCLUSION: Whether low DHEAS levels might contribute to some of the pathophysiologic features and/or symptoms seen in HIV infection needs to be investigated.

Blood dehydroepiandrosterone sulphate (DHEAS) levels in polymyalgia rheumatica/giant cell arteritis and primary fibromyalgia.

Blood levels of dehydroepiandrosterone sulphate (DHEAS) were measured by radioimmunoassay (RIA) in patients with: a) polymyalgia rheumatica/giant cell arteritis (PMR:TA; N = 25), with and without cortisone derivative treatment (N = 10 and N = 15, respectively); and b) primary fibromyalgia (PF; N = 15). The mean DHEAS levels were found to be significantly reduced in PMR:TA, compared to those in PF (Geom. mean 820 vs. 2300 nmol/l, respectively; p < 0.001), and the reduction was more marked in patients on cortisone derivative treatment. The DHEAS levels found in PF were found to be normal and consistent with those previously reported in non-immune mediated rheumatological diseases such as osteoarthritis, and in healthy subjects, using the same method of analysis. The low levels found in patients with PM:TA are in accordance with those previously reported in immune-mediated diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis, suggesting that diminution of DHEAS is a constant endocrinologic feature in these categories of patients. The pathophysiological significance of these low DHEAS levels needs to be investigated.

Relationship between blood and joint tissue DHEAS levels in rheumatoid arthritis and osteoarthritis.

To assess the relationship between blood and tissue steroid levels, cortisol and dehydroepiandrosterone sulphate (DHEAS) were measured by radioimmunoassay (RIA) in blood and joint tissues from a group of patients with RA (N = 29) ranging in age from 26 to 80 years (mean 63, SD: 13) and another group with secondary osteoarthritis (OA; N = 23), ranging in age from 47 to 86 years (mean 66, SD: 9), all of whom were scheduled for surgical correction of joint dysfunction. Seventeen of the RA patients were on steroid treatment at the time of the study. Assessing all the patients together, it was found that the tissue concentrations of DHEAS very closely paralleled the blood levels (r = 0.875; p < 0.001). The mean blood and tissue concentrations of DHEAS were found to be significantly reduced in RA, compared to those in OA (geometric means 540 vs. 2100 nmol/l blood, respectively, and 160 vs. 420 nmol/kg tissue, p < 0.001). Individual data indicated, however, that: (a) 3/29 patients with RA exhibited normal levels; (b) the reduction was more accentuated in those patients on steroid treatment; and (c) 5/23 patients with OA, who were treated for cardiovascular disorders, also had reduced DHEAS levels. Significant differences were not found between the mean cortisol levels in RA and those in OA, nor was there a correlation between the blood and tissue levels of this steroid. The possible influence of reduced DHEAS levels on immune-mediated diseases and/or pathophysiology is unknown, and needs to be investigated.

Intratesticular steroid levels and their hormonal control.

Litter-mate adult male rats were treated with daily intramuscular injections of ACTH (10.5 micrograms), dexamethasone (2.0 mg), ethynyl estradiol (1.7 micrograms) and hCG (5 IU) for three consecutive days. The animals were sacrificed on the fourth day and the intratesticular and peripheral plasma steroid levels were analyzed. The steroids measured by radioimmunoassay included pregnenolone, 17-hydroxypregnenolone, dehydroepiandrosterone, progesterone, 17-hydroxyprogesterone, androstenedione, testosterone and dihydrotestosterone. In addition, the sulphoconjugated forms of pregnenolone, dehydroepiandrosterone, testosterone and dihydrotestosterone were estimated in the peripheral blood. The administration of ACTH diminished the intratesticular levels of all steroids studied. Also dexamethasone and ethynyl estradiol treatment suppressed all intratesticular steroid levels, except that of pregnenolone (the former) and of 17-hydroxyprogesterone (the latter). The suppressive effect of ethynyl estradiol was strongest on the levels of the delta 5-steroids and that of dexamethasone on the delta 4-steroids; the latter was significantly stronger than the effect of ACTH. The stimulatory effect of hCG was limited to the metabolism of progesterone and was restricted to the sequence: 17-hydroxyprogesterone----androstenedione----testosterone---- dihydrotestosterone. Dexamethasone-suppression, and hCG-stimulation of the intratesticular levels of delta 4-steroids, was mirrored by corresponding changes in the peripheral plasma levels, with the exception of the plasma levels of androstenedione which were not influenced by any of the treatments studied. Also the suppression of intratesticular testosterone and dihydrotestosterone levels by ACTH, dexamethasone, or ethynyl estradiol was closely reflected by their plasma levels both in the unconjugated and sulphoconjugated forms. On the hand, the administration of ACTH diminished the intratesticular levels of pregnenolone and progesterone but significantly increased those in the plasma. Moreover, both ACTH and ethynyl estradiol reduced the levels of all delta 5-steroids in testicular tissue, but not in the peripheral plasma, although they decreased the circulating levels of pregnenolone sulphate and dehydroepiandrosterone sulphate. The data are interpreted as suggesting that the hormonal agents studied interfere with testicular steroidogenesis through different mechanisms.

Psoriatic fibroblasts secrete lower amounts of IL-6 than healthy fibroblasts before and after stimulation with TNF-alpha.

Altered function of the fibroblasts is thought to contribute to the pathogenesis of psoriasis. To further elucidate this point, we compared the ability of fibroblasts from psoriatic lesions and of fibroblasts from healthy individuals to produce interleukin-6 (IL-6). The IL-6 levels were measured by ELISA in serum-free culture medium before and after stimulation of monolayer fibroblasts with various concentrations of tumour necrosis factor-alpha (TNF-alpha), platelet-derived growth factor (PDGF), and interferon-gamma (IFN-gamma), alone and in different combinations. The production of IL-6 in the fibroblast cultures was stimulated by TNF-alpha (0.01-10 nm/ml medium) in a dose-dependent way. Fibroblasts from psoriatic lesions produced lower amounts of IL-6 than fibroblasts from healthy individuals both before and after stimulation with the different concentrations of TNF-alpha (P = 0.012). The ratios between the IL-6 concentrations before and after stimulation with TNF-alpha were similar in both types of fibroblasts, indicating that the capacity to produce IL-6 is reduced in psoriatic fibroblasts compared with healthy ones. The production of IL-6 was not influenced by either PDGF or IFN-gamma. These findings support the view that the phenotype of the fibroblast is altered in psoriasis.