Ghrelin and growth hormone serum levels during the clonidine test in children with short stature and variable growth hormone status

OBJECTIVE

The exact role of ghrelin in the control of growth hormone (GH) secretion has not been completely clarified as yet. The aim of the present study was 1) to investigate the effect of a substance promoting GH secretion (clonidine) on ghrelin levels in children with short stature with growth hormone deficiency (GHD) and normal growth hormone (NGH), and 2) to assess possible correlations between GH and ghrelin values during the clonidine test.

DESIGN

Eighteen prepubertal children with short stature were included in the study. Using the results of two GH-provocative tests (glucagon and clonidine), the participants were divided into two groups: GHD and NGH. In both groups, ghrelin levels were determined during the clonidine stimulation test.

RESULTS

Different responses regarding ghrelin levels during the clonidine stimulation test were observed in the two study groups (GHD and NGH). A decrease in ghrelin levels was observed in the NGH children accompanied by a rise in the circulating GH levels, whereas the GHD children demonstrated a rise in both ghrelin and GH levels.

CONCLUSIONS

The data indicate an inverse relationship between circulating ghrelin and GH in NGH children, suggesting the presence of a negative feedback loop between ghrelin and GH. Analogous changes were not observed in GHD children.

Involvement of signaling molecules on na/h exchanger-1 activity in human monocytes

Background:

Sodium/hydrogen exchanger-1 (NHE-1) contributes to maintaining intracellular pH (pHi). We assessed the effect of glucose, insulin, leptin and adrenaline on NHE-1 activity in human monocytes in vitro. These cells play a role in atherogenesis and disturbances in the hormones evaluated are associated with obesity and diabetes.

Methods and Results:

Monocytes were isolated from 16 healthy obese and 10 lean healthy subjects. NHE-1 activity was estimated by measuring pHi with a fluorescent dye. pHi was assessed pre- and post-incubation with glucose, insulin, leptin and adrenaline. Experiments were repeated after adding a NHE-1 inhibitor (cariporide) or an inhibitor of protein kinase C (PKC), nitric oxide synthase (NOS), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, phosphoinositide 3-kinases (PI3K) or actin polymerization. Within the whole study population, glucose enhanced NHE-1 activity by a processes involving PKC, NOS, PI3K and actin polymerization (p = 0.0006 to 0.01). Insulin-mediated activation of NHE-1 (p = <0.0001 to 0.02) required the classical isoforms of PKC, NOS, NADPH oxidase and PI3K. Leptin increased NHE-1 activity (p = 0.0004 to 0.04) through the involvement of PKC and actin polymerization. Adrenaline activated NHE-1 (p = <0.0001 to 0.01) by a process involving the classical isoforms of PKC, NOS and actin polymerization. There were also some differences in responses when lean and obese subjects were compared. Incubation with cariporide attenuated the observed increase in NHE-1 activity.

Conclusions:

Selective inhibition of NHE-1 in monocytes could become a target for drug action in atherosclerotic vascular disease.

Evaluation of prooxidant-antioxidant balance in chronic heroin users in a single assay: an identification criterion for antioxidant supplementation

BACKGROUND

Opiate abuse has been linked to oxidative stress, through the separate evaluation of oxidants and antioxidants.

OBJECTIVES

To determine prooxidant-antioxidant balance (PAB) in chronic heroin users in a single assay, easily applied in a clinical setting. Specifically, to examine whether PAB values correlate with the duration of abuse or with the presence of anti-HCV antibodies.

METHODS

Sixty-four chronic heroin users - 34 cases and 30 controls - participated in this study. PAB was determined by an Enzyme-linked immunosorbent assay (ELISA) method, developed by members of the study group.

RESULTS

In heroin users, oxidative balance was disrupted in favor of prooxidants. There was no correlation of PAB values with the duration of abuse or with the presence of anti-Hepatitis C virus (HCV) antibodies.

CONCLUSIONS

Chronic heroin users can benefit from an antioxidant therapy, and the method currently presented can be used as an identification criterion.

Effect of epinephrine and insulin resistance on human monocytes obtained from lean and obese healthy participants: a pilot study

We assessed the effect of epinephrine on human monocytes. Monocytes were isolated from 16 healthy obese and 10 lean healthy subjects. Insulin sensitivity was assessed by euglycemic hyperinsulinemic clamp. Obese subjects were subdivided into 2 sub-groups, insulin sensitive (IS) and insulin resistant (IR). Monocyte properties [attachment to laminin 1, migration through laminin 1, oxidized-low density lipoprotein (oxLDL) phagocytosis] were assessed pre- and post-stimulation in vitro with epinephrine. Experiments were repeated after incubation with a Na(+)/H( +) exchanger-1 inhibitor (NHE-1) (cariporide). Epinephrine increased monocyte attachment to laminin in lean and obese IR subjects through involvement of NHE-1, PKC, NO synthase, NADPH oxidase and actin polymerization. In contrast, epinephrine did not affect monocyte migration. Epinephrine increased oxLDL phagocytosis in all groups studied. Incubation with cariporide attenuated oxLDL phagocytosis. Epinephrine induces monocyte dysfunction which may be atherogenic.

Effect of glucose and insulin on oxidized low-density lipoprotein phagocytosis by human monocytes: a pilot study

We assessed the effect of glucose and insulin on human monocytes. Monocytes were isolated from 16 healthy obese and 10 lean healthy participants. Insulin sensitivity was assessed by euglycemic hyperinsulinemic clamp. Obese participants were subdivided into 2 subgroups: insulin sensitive (IS) and insulin resistant (IR). Monocyte oxidized low-density lipoprotein (oxLDL) phagocytosis was assessed pre and poststimulation in vitro with glucose or insulin. Experiments were repeated after incubation with a Na(+)/H(+) exchanger-1 inhibitor ([NHE-1]; cariporide) or rosiglitazone. Glucose increased oxLDL phagocytosis in all groups studied (at 1 or 3 hours incubation; P = .037-.002). Insulin increased oxLDL phagocytosis in all groups studied after 1-hour incubation (P = .027-.015) but not at 3 hours. Incubation with cariporide attenuated oxLDL phagocytosis except in the obese IS group. Rosiglitazone eliminated glucose- and insulin-induced increase in oxLDL phagocytosis in all studied groups. Glucose and insulin induce oxLDL phagocytosis.

Effect of leptin and insulin resistance on properties of human monocytes in lean and obese healthy participants

We assessed the effect of leptin on human monocytes. Monocytes were isolated from 16 healthy obese and 10 lean healthy participants. Insulin sensitivity was assessed by euglycemic hyperinsulinemic clamp. Obese participants were subdivided into 2 subgroups, insulin sensitive (IS) and insulin resistant (IR). Monocyte properties (attachment to laminin 1, migration through laminin 1, surface expression of CD36, oxidized low-density lipoprotein [oxLDL] phagocytosis) were assessed pre- and poststimulation in vitro with leptin. Experiments were repeated after incubation with rosiglitazone and a Na(+)/H(+) exchanger-1 inhibitor (cariporide). We found a significant correlation between insulin resistance and monocyte attachment to laminin and oxLDL phagocytosis. Leptin increased the atherosclerosis-related properties of monocytes in all groups, apart from surface expression of CD36 in IS obese participants. Incubation with rosiglitazone or cariporide attenuated the observed effects. Leptin induces monocyte dysfunction which may be atherogenic. Correlation with insulin resistance suggests that atherosclerosis might be accelerated before the onset of diabetes.

Addition of adipose-derived stem cells in cord blood cultures stimulates their pluripotent differentiation

INTRODUCTION

Adipose tissue is recognized as an important source of postnatal mesenchymal stem cells for generative medicine applications. Moreover, cord blood stem cells have been shown to contain pluripotent stem cells called unrestricted somatic stem cells (USSCs). However, this population is rare and cannot be generated from every cord blood sample. In this study, we have presented a new method of co-culture of adipose-derived stem cells (ADPCs) and cord blood stem cells that results in pluripotent differentiation.

MATERIALS AND METHODS

ADPCs were obtained from a piece of adipose tissue after treatment with 0.075% collagenase, which was subsequently inactivated with DMEM/10% FBS. The cellular pellet of centrifugation was plated at 5-7 x 10(6) cells/mL in T25 culture flasks in a low-glycose DMEM with 30% FCS. Cord blood stem cells were obtained by centrifugation following double-processing in the presence of 2% HES 200/0.5 and plated at 5-7 x 10(6) cells/mL in the same medium. To investigate the crucial role of ADPCs in pluripotent cord blood differentiation, we added a ADPCS as (1 x 10(4) cells/mL) to the cord blood cultures and analyzed the contribution of ADPCs using a microscope as well as with flow cytometry.

RESULTS

After only 3 days, adherent cells (USSC colonies) of fibroblastic morphology were detected in all co-cultured samples, whereas this was observed later or not at all in the non-co-cultured samples. The greater density of colonies in the co-coltured samples was another point. Hematopoietic CD45 cells were no longer detected after the first passage. Pluripotent stem cells were obtained from all co-cultured samples that contained stem cells positive for CD29, CD44, CD49e, CD90, CD105, CD51 Stro, and C-kit antibodies but negative for CD34, CD45, CD133, and glycophorin A.

CONCLUSION

Addition of ADPCs was crucial to generate pluripotent-derived stem cells from cord blood samples. This double culture may be a useful tool for a universal allogeneic stem cell source for tissue repair or regeneration.

Oxidized laminin-1 induces increased monocyte attachment and expression of ICAM-1 in endothelial cells

Atherosclerosis has been associated with increased oxidative stress and monocyte recruitment by endothelial cells. Sub-endothelial basement membrane proteins, such as laminins that play a central role in cell adhesion, are exposed to reactive oxygen species. In the present study monocyte attachment on human umbilical cord vein endothelial cells (HUVEC) that were preattached to oxidized or native laminin, was investigated. Intracellular cell adhesion molecule-1 (ICAM-1) expression by HUVEC was estimated by an enzyme-linked immunosorbent assay. HUVEC attachment to oxidized or native laminin-1 was examined using the Hemacolor kit. Anti-alphaL, anti-alphaM, anti-alpha2 and anti-beta2 integrin subunit antibodies were used in order to further investigate the above phenomena. HUVEC that were preattached to oxidized laminin expressed higher levels of ICAM-1 and monocytes attached at a higher degree to these cells as compared to HUVEC that were preattached to native laminin. Incubation of monocytes with monoclonal antibodies against the alphaM and beta2 integrin subunits equalized the above mentioned differences. Moreover, HUVEC attached to oxidized laminin at a higher degree as compared to native laminin. This difference was equalized after incubation with the antibody against the alpha2 integrin subunit. These results indicate a modified interaction between HUVEC and the basement membranes in cases where laminin is oxidatively modified. This modified interaction results in increased ICAM-1 expression by endothelial cells and consequently increased monocyte recruitment capacity.

Progression of mild cognitive impairment to Alzheimer's disease: improved diagnostic value of the combined use of N200 latency and beta-amyloid(1-42) levels

BACKGROUND/AIMS

The aim of this study was to investigate the role of cerebrospinal fluid beta-amyloid(1-42) levels and auditory event-related potentials (AERPs) in the progress of mild cognitive impairment (MCI) to Alzheimer's disease (AD).

METHODS

In 53 MCI patients, lumbar puncture was performed and beta-amyloid(1-42) levels were determined. Twenty patients were reexamined after 11 months. During this period, 5 of them progressed to AD. Neuropsychological and ERP analyses were performed on all patients during both baseline and endpoint examinations.

RESULTS

Compared to stable MCI patients, those that progressed to AD had significantly lower beta-amyloid(1-42) levels (Mann-Whitney test, Z = -2.952, p = 0.003; effect size r = -0.41) and significantly prolonged N200 latencies (Mann-Whitney test, Z = -3.561, p < 0.001, effect size r = -0.49). From ERP variables, only the N200 latency significantly correlated with beta-amyloid(1-42) levels (baseline examination: r(s) = -0.421, p = 0.002; follow-up examination: r(s) = -0.574, p = 0.008).

CONCLUSIONS

The combined use of these two parameters enabled discrimination of stable MCI patients from those who developed AD, with 100% sensitivity and specificity. Therefore, this method could be of high diagnostic value for the early diagnosis of AD.

The ambiguous role of the Na+-H+ exchanger isoform 1 (NHE1) in leptin-induced oxidative stress in human monocytes

Leptin, a 16-kDa cytokine produced mainly by the adipose tissue, is known to increase energy expenditure while at the same time lowering food intake by acting directly on the hypothalamus. ObRb, the leptin receptor mostly involved in intracellular signaling, is expressed in a wide range of tissues, thus allowing leptin to affect a much broader diversity of biological processes. High concentrations of leptin are encountered in patients with hyperleptinemia, a condition which very often accompanies obesity and which is a direct result of leptin resistance. In the present study, moderate and high concentrations of leptin (16 and 160 ng/ml) were mostly utilized in order to investigate the role of this cytokine in oxidative stress levels in human monocytes. Leptin was found to increase oxidative species production as measured with 2',7'-dichlorodihydrofluorescein diacetate (general marker of oxidative species, but not O2-*) and dihydroethidium (marker of O2-*). Surprisingly, it also augmented superoxide dismutase activity. Inhibition of the Na+-H+ exchanger isoform 1 (NHE1) also inhibited leptin-induced superoxide anion production but at the same time amplified leptin-induced production of other oxidative species. Signaling proteins such as phosphoinositide 3 kinase and conventional isoforms of protein kinase C (alpha-, beta(i)-, beta(ii)-), as well as NADPH oxidase, also participated in leptin signaling. Finally, leptin was found to increase glutathionylation levels of NHE1-bound heat shock protein 70 kDa (Hsp70) but not Hsp70 binding to NHE1.

Oxidative effects of inorganic and organic contaminants on haemolymph of mussels

We applied a newly-established method in haemolymph of mussels, Mytilus galloprovincialis, exposed to different concentrations of heavy metals, such as zinc and cadmium and organic pollutants, such as PAHs and lindane, for the detection of total antioxidant capacity (TAC). The susceptibility of exposed mussels was increased in relation to oxidative stress induced by contaminants tested. Oxidative modifications of proteins were estimated by measuring protein carbonyl content (PCC) and malondialdehyde levels (MDA). For PCC measurement, a highly sensitive and accurate ELISA method, which requires only 5 microg of protein, was used. The significant increase of PCC and MDA in haemolymph of exposed mussels reinforces its role as biomarkers of oxidative stress. Significant correlation of TAC assay, PCC and MDA was conducted in order to evaluate the utility of PCC and TAC assay, used in the present study, as tools for determining oxidative effects of pollutants in mussels. The results reinforce the application of PCC method as useful tool for the determination of PCC alterations in haemolymph of mussels exposed to different levels of contaminants. In addition, the TAC method gives encouraging results, concerning its ability to predict antioxidant efficiency in haemolymph of mussels exposed to inorganic and organic contaminants.

Late postoperative opacification of hydrogel intraocular lenses: analysis of 13 explanted lenses

PURPOSE

We report the clinical, morphological, and ultrastructural findings of 13 consecutively explanted opacified Hydroview(R) (hydrogel) intraocular lenses (IOLs). Our purpose was to provide a comprehensive account on the possible factors involved in late postoperative opacification of these IOLs.

PATIENTS AND METHODS

Thirteen consecutive opacified hydrogel IOLs (Hydroview H 60 M, Bausch & Lomb) were explanted due to the significant visual impairment they caused. The IOLs underwent macroscopical examination, transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrophoresis for protein detection. Three unused control Hydroview IOLs served for comparison.

RESULTS

Macroscopical examination showed a diffuse or localized grey-whitish opacification within the IOL optic. TEM confirmed the presence of lesions inside the optic in all the explanted IOLs and revealed 3 patterns of deep deposits: a) diffuse, thick, granular, electron-dense ones; b) small, thin, lattice-like ones, with prominent electron-lucent areas; and c) elongated electron-dense formations surrounded by electron-lucent halos. SEM showed surface deposits on four IOLs. EDS revealed oxygen and carbon in all IOLs and documented calcium, phosphorus, silicon and/or iron in the deposits. Two of the patients with iron in their IOLs had eye surgery prior to their phacoemulsification. Iron correlated well with the second TEM pattern of deep lesions, whereas calcium with the third TEM pattern. No protein bands were detected on electrophoresis. Control lenses did not show any ultrastructural or chemical abnormality.

CONCLUSIONS

The present study supports the presence of chemical alterations inside the polymer of the optic in late postoperative opacification of Hydroview IOLs. This opacification does not follow a unique pathway but may present under different ultrastructular patterns depending on the responsible factors. Mechanical stress during surgery may initiate a sequence of events where ions such as calcium, phosphorus, silicon, and/or iron, participate in a biochemical cascade that leads to gradual alteration of the polymer network. Intraocular inflammation due to previous operation may be a factor inducing opacification through increase of iron-binding capacity in the aqueous humour. Calcification accounts only partially for the opacification noted in this type of IOL.

Monocyte attachment to laminin in diabetes mellitus: The role of ATP

Monocyte-extracellular matrix interactions have been implicated in atherosclerosis pathophysiology. Laminin, the main basement membrane protein contains cell binding domains that can be cryptic, presented only after protein modification. In the present study we evaluated monocyte attachment to laminin-1 in the presence of ATP. Monocytes were derived from either healthy volunteers or patients with diabetes mellitus type II. For the estimation of monocyte attachment to laminin the myeloperoxidase assay was used. Monocytes derived from diabetic patients, showed an increased ability to attach to laminin (p = 0.0055). The presence of ATP increased the attachment of control monocytes to laminin (p = 0.0022). On the contrary, the presence of ATP did not affect the attachment of monocytes derived from diabetic patients to laminin. Our results indicate a modified interaction between monocytes and laminin-1 in diabetes mellitus.

Receptor of Advanced Glycation End Products (RAGE) Positively Regulates CD36 Expression and Reactive Oxygen Species Production in Human Monocytes in Diabetes

Introduction: Advanced glycation end products (AGEs) engagement of a monocyte surface receptor (RAGE) induces atherosclerosis. AGEs also act as CD36 ligands. We studied reactive oxygen species (ROS) and CD36 expression after siRNA inhibition of RAGE expression in human monocytes. Methods: We isolated monocytes from: a) 10 type 2 diabetics, and b) 5 age- and sex-matched healthy individuals. CD36 expression and ROS production were evaluated before and after RAGE knockdown. Results: After incubation of monocytes with AGE + bovine serum albumin (BSA), CD36 expression and intracellular ROS increased significantly in all groups. In RAGE-knockdown monocytes, AGE-induced CD36 expression and ROS generation were also significantly inhibited. Conclusions: Blocking RAGE expression using siRNA in human monocytes led to a significant inhibition of CD36 expression and ROS production, suggesting a positive interaction between RAGE, CD36 expression and ROS generation in monocytes.

Fibrinogen beta-chain tyrosine nitration is a prothrombotic risk factor

Elevated levels of circulating fibrinogen are associated with an increased risk of atherothrombotic diseases although a causative correlation between high levels of fibrinogen and cardiovascular complications has not been established. We hypothesized that a potential mechanism for an increased prothrombotic state is the post-translational modification of fibrinogen by tyrosine nitration. Mass spectrometry identified tyrosine residues 292 and 422 at the carboxyl terminus of the beta-chain as the principal sites of fibrinogen nitration in vivo. Immunoelectron microscopy confirmed the incorporation of nitrated fibrinogen molecules in fibrin fibers. The nitration of fibrinogen in vivo resulted in four distinct functional consequences: increased initial velocity of fibrin clot formation, altered fibrin clot architecture, increased fibrin clot stiffness, and reduced rate of clot lysis. The rate of fibrin clot formation and clot architecture was restored upon depletion of the tyrosine-nitrated fibrinogen molecules. An enhanced response to the knob "B" mimetic peptides Gly-His-Arg-Pro(am) and Ala-His-Arg-Pro(am) suggests that incorporation of nitrated fibrinogen molecules accelerates fibrin lateral aggregation. The data provide a novel biochemical risk factor that could explain epidemiological associations of oxidative stress and inflammation with thrombotic complications.

Asymmetrical dimethylarginine in systemic sclerosis-related pulmonary arterial hypertension

OBJECTIVES

SSc is a CTD characterized by vascular involvement, with generalized disturbance of the microcirculation, which may lead to pulmonary artery hypertension (PAH). Asymmetrical dimethylarginine (ADMA) is an endogenous nitric oxide (NO) inhibitor. Increased concentrations of plasma ADMA may also contribute to endothelial dysfunction in patients with pulmonary vascular disease. The aim of our study was to elucidate the possible relationship between serum ADMA and PAH in patients with SSc. Moreover, we sought to investigate the effect of ADMA levels on the functional capacity of these patients.

METHODS

Plasma ADMA levels were measured in 66 patients with SSc (63 females, mean age 57.8 +/- 12.8 yrs, median duration of disease 9.9 yrs, 47 with lcSSc and 19 with dcSSc disease) and 30 healthy controls (29 females, mean age 58.2 +/- 8.4 yrs). Systolic pulmonary artery pressure (sPAP) assessed by echocardiography, lung function tests, 6-min walk test (6MWT) and serum ADMA levels were recorded from patients.

RESULTS

In 24 patients, the diagnosis of PAH was established. Mean value of ADMA for SScPAH patients was 0.44 +/- 0.22 micromol/l compared with 0.26 +/- 0.18 micromol/l for patients without PAH and 0.25 +/- 0.20 micromol/l for controls (P = 0.001). ADMA levels were inversely correlated with the 6MWT (r = -0.55, P = 0.005).

CONCLUSIONS

In patients with SScPAH, increased ADMA serum levels and their negative association with exercise capacity suggests that the NO pathway is involved in the development of pulmonary vascular disease.

Serum and seminal plasma ghrelin levels in men with normospermia and dyspermia

AIMS

To investigate the existence of ghrelin in seminal plasma and the levels of serum ghrelin in men with normospermia and dyspermia.

SUBJECTS AND METHODS

Ninety-eight men were classified into three groups: Group 1, men with normospermia and proven fertility (n = 26); Group 2, men with idiopathic oligo-astheno-teratozoospermia (n = 62); and Group 3, men with idiopathic azoospermia (n = 10). Spermiograms and determination of ghrelin in serum and seminal plasma were performed in all men.

RESULTS

Ghrelin was present in the seminal plasma of men from all groups at a concentration of 27%, 18% and 30% of the corresponding serum levels (mean +/- standard error: Group 1, 127.7 +/- 14.7 vs. 468.3 +/- 35.5 pmol/l, p = 0.003; Group 2, 117.0 +/- 10.1 vs. 637.0 +/- 29.3 pmol/l, p < 0.001; Group 3, 166.2 +/- 32.5 vs. 557.7 +/- 25.4 pmol/l, p = 0.068). When Group 1 men were compared with men from Groups 2 and 3 combined, there were no significant differences in serum (mean +/- standard error: 468.3 +/- 35.5 vs. 628.0 +/- 26.4 pmol/l, p = not significant) or seminal plasma ghrelin (mean +/- standard error: 127.7 +/- 14.7 vs. 123.9 +/- 9.9 pmol/l, p = not significant). In the total group of studied men (Groups 1 to 3), serum ghrelin was positively correlated with semen volume (r = 0.309, p = 0.037), whereas seminal plasma ghrelin was negatively correlated with age (r = -0.268, p = 0.008) and semen volume (r = -0.385, p < 0.000).

CONCLUSIONS

Ghrelin is present in human seminal plasma at lower levels than in serum. There is no difference in seminal plasma ghrelin levels between men with normospermia and dyspermia.