Stability and Temperature-Induced Agglomeration of Rh Nanoparticles Supported by CeO2.

The effects of reduction by H2 and by heat treatment in vacuum and in O2 flow on Rh particle size changes of Rh/CeO2 samples were studied by X-ray photoelectron spectroscopy (XPS), high-resolution electron microscopy (HRTEM), and CO adsorption followed by diffuse reflectance infrared spectroscopy (DRIFTS). Low-temperature (373-423 K) reduction of Rh without agglomeration is demonstrated. An average particle size of 2.3 ± 1.1 nm was measured by HRTEM regardless of the metal loading (1-5%). On Rh/CeO2, a significant particle size increase of the Rh particles was detected on heating (773 K). In this work, we suggest that the temperature-induced surface decrease resulting from the sintering of Rh is favored only for well-dispersed particles. XP spectra revealed that the mobile oxygens of CeO2 fundamentally determine the oxidation state of the supported metals. At elevated temperature, the oxidation of the reduced support surface as well as the metal component takes place because of the segregation of ceria oxygens. When the aggregated particles were reoxidized, the redispersion of Rh was observed probably because of the formation of Rh-O-Ce bonds.

Cord serum dipeptidyl-peptidase 4 activity in gestational diabetes.

BACKGROUND: Tissue-specific dipeptidyl-peptidase 4 (DPP4) dysregulation has been described in adults with diabetes mellitus. The DPP4 -incretin system has not been studied in foetal life. In this study, DPP4 activity and glucagon-like peptide-1 (GLP-1) levels were assessed in cord blood of neonates born to women with gestational diabetes mellitus (GDM) and nondiabetic controls. MATERIAL AND METHODS: This study has been conducted in two Hungarian and one Austrian centres. PATIENTS: A total of 568 pregnant women were enrolled in the study after their OGTT between the 24th and 28th gestational week. Cord blood samplings with DPP4 activity and GLP-1 level measurements were possible in 270 (DPP4: 159 control, 111 GDM) and 112 (GLP-1: 72 control, 40 GDM) cases. OGTT (24-28th gestational week) and cord blood sampling at delivery were performed. Cord serum DPP4 activity was determined in a continuous monitoring microplate-based kinetic assay, and cord plasma GLP-1 was measured using a fluorescence ELISA method. RESULTS: Cord serum DPP4 activity was lower in GDM [mean (95% CI): 28.07 U/L (26.32-29.82 U/L)] than in controls [31.61 U/L (29.93-33.29 U/L), MWU P = 0.0015]. Cord plasma active GLP-1 levels were close to the lower detection limit and were not altered in GDM (control: mean = 3.43 pM, 95% CI: 3.04-3.82 pM, GDM: mean = 3.61 pM, 95% CI: 2.96-4.28 pM - MWU test P = 0.6). CONCLUSIONS: Decreased cord serum DPP4 activity in gestational diabetes mellitus might be the result of an adaptive foetal response or an early dysregulation in the entero-insular axis with consequences beyond the incretin system. Cord plasma GLP-1 levels may reflect the missing oral intake with a limited glucose sensing of L cells via the circulation in foetal life.

[Analysis of laboratory data of 155 patients with pheochromocytoma-paraganglioma syndrome diagnosed during the past 20 years]. / A laboratóriumi diagnosztika eredményei az elmúlt 20 évben kórismézett 155 phaeochromocytoma/paraganglioma szindrómás beteg adatainak elemzése alapján.

INTRODUCTION: Laboratory diagnosis of pheochromocytoma-paraganglioma syndrome has been markedly improved during the past two decades. AIM: Retrospective assessment of diagnostic utility of urinary catecholamines and their metabolites as well as serum chromogranin A in 155 patients diagnosed at the 2nd Department of Medicine, Semmelweis University. METHOD: Urinary catecholamines and metabolites were measured using high-performance liquid chromatography with electrochemical detection in 155 patients with pheochromocytoma-paraganglioma (of whom 28.4% had hereditary background) and in 170 non-pheochromocytoma patients used as controls. Serum chromogranin A was measured by immunoradiometry. RESULTS: Sensitivity (93.2%) and specificity (87.0%) of urinary fractionated metanephrines were higher than those of urinary catecholamines (90.9% vs. 85.7%, respectively) and serum chromogranin A (88.7% and 77.5%, respectively). Urinary normetanephrine and serum chromogranin A correlated positively with tumor size (r = 0.552, p<0.0001 and r = 0.618, p<0.0001, respectively). CONCLUSIONS: These data confirm the diagnostic utility of urinary catecholamines and their metabolites. Urinary normetanephrine and serum chromogranin A may help to estimate tumour mass and probably tumour progression.

General and electrophysiological toxic effects of manganese in rats following subacute administration in dissolved and nanoparticle form.

In an attempt to model occupational and environmental Mn exposures and their possible interaction, young male Wistar rats were exposed to Mn by oral administration in dissolved form (MnCl(2)·4H(2)O, 14.84 and 59.36 mg/kg b.w.) and by intratracheal application of MnO(2) nanoparticles (2.63 mg/kg b.w.). After 3 and 6 weeks oral, or 3 weeks oral plus 3 weeks intratracheal, exposure, general toxicological, and electrophysiological tests were done. Body weight gain was significantly reduced after 6 and 3 plus 3 weeks exposure, but the effect of the latter on the pace of weight gain was stronger. Organ weights signalized systemic stress and effect on lungs. Changes in evoked electrophysiological responses (cortical sensory evoked potential and nerve action potential) indicated that the 3 plus 3 weeks combined exposure caused equal or higher changes in the latency of these responses than 6 weeks of exposure, although the calculated summed Mn dose in the former case was lower. The results showed the importance of the physicochemical form of Mn in determining the toxic outcome, and suggested that neurofunctional markers of Mn action may indicate the human health effect better than conventional blood Mn measurement.

Low-temperature large-scale synthesis and electrical testing of ultralong copper nanowires.

Copper nanowires (NWs) with uniform diameters and lengths ranging from several hundreds of nanometers to several micrometers have been prepared with high yield by a simple hydrothermal procedure. The X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS) analysis data indicate that the copper nanowires are free of any contamination, while the electron diffraction (ED) analysis has revealed the nanowires to be single crystals. The nanowire growth mechanism has also been discussed. Hexadecylamine is the surface stabilizing agent in our method, while glucose facilitates formation of single-crystalline seeds on which the copper nanowires grow. The electrical properties of the as-synthesized copper NWs have also been investigated.

[Outcome of somatostatin analogue treatment in acromegaly]. / A szomatosztatinanalóg kezelés eredményei acromegaliában.

UNLABELLED: During the past decade the importance of medical therapy, especially treatment with somatostatin analogues has increased significantly in patients with active acromegaly. AIMS: Authors analyzed the outcome of somatostatin analogue treatment in acromegalic patients evaluated and followed up at the 2nd Department of Medicine, Faculty of Medicine, Semmelweis University, during the past 10 years. PATIENTS AND METHODS: Changes in serum growth hormone (GH) and insulin-like growth factor-1 (IGF-1) concentration, as well as morphologic changes of pituitary adenomas followed by MRI scans were evaluated and compared in 32 acromegalic patients (26 women, 6 men) during long-term somatostatin analogue treatment (mean+/-SE, 3.1+/-0.3 years, range, 1-7 years). Primary somatostatin analogue treatment was applied in 10 patients (7 women and 3 men), whereas 15 patients (14 women and 1 man) had pituitary surgery and 7 patients (5 women and 2 men) underwent both pituitary surgery and irradiation therapy prior to somatostatin analogue treatment. RESULTS: After a 3-month treatment with somatostatin analogues, both serum GH and IGF-1 levels decreased significantly and they remained around the same decreased levels throughout the treatment period. Serum GH decreased from 15.7+/-4.9 to 5.5+/-1.4 ng/ml, and serum IGF-1, expressed as a percentage of the upper limit of age- and sex-adjusted reference value, decreased from 204+/-14% to 135+/-12% at the end of treatment. The efficacy of somatostatin analogue treatment was not influenced by surgical or surgical and irradiation therapies which were applied prior to medical treatment. At the end of treatment 36.7% of patients had safe serum GH (<2.5 ng/ml), while serum IGF-1 returned below the upper limit of age- and sex-adjusted reference range in 41.4% of patients. Pituitary MRI showed regression of the adenoma in 46% of patients, and none of the patients had progression of the pituitary adenoma. CONCLUSIONS: Somatostatin analogues are effective therapeutic options for acromegalic patients when primary surgical treatment cannot be performed due to complications and associated disorders, or in patients whose acromegaly remains active after pituitary surgery or after pituitary surgery and irradiation.

True MEN1 or phenocopy? Evidence for geno-phenotypic correlations in MEN1 syndrome.

PURPOSE: Multiple endocrine neoplasia type 1 is a rare tumor syndrome caused by germline mutations of MEN1 gene. Phenotype varies widely, and no definitive correlation with the genotype has been observed. Mutation-negative patients with MEN1-associated tumors represent phenocopies. By comparing mutation-positive and mutation-negative patients, we aimed to identify phenotype features predictive for a positive genetic test and to evaluate the role of MEN1 mutations in phenotype modulation. METHODS: Mutation screeening of MEN1 gene by Sanger sequencing and assessment of clinical data of 189 consecutively enrolled probands and relatives were performed at our national and European Reference Center. Multiple ligation probe amplification analysis of MEN1 gene and Sanger sequencing of CDKN1B were carried out in clinically suspicious but MEN1-negative cases. RESULTS: Twenty-seven probands and twenty family members carried MEN1 mutations. Five mutations have not been described earlier. Pronouncedly high number of phenocopies (>70%) was observed. Clinical suspicion of MEN1 syndrome emerged at significantly earlier age in MEN1-positive compared to MEN1-negative probands. Gastroenteropancreatic neuroendocrine tumors developed significantly earlier and more frequently in carriers compared to non-carriers. Probands with high-impact (frameshift, nonsense, large deletions) mutations, predicted to affect menin function significantly, developed GEP-NETs more frequently compared to low-impact (inframe and missense) mutation carriers. CONCLUSIONS: MEN1 phenocopy is common and represents a significant confounder for the genetic testing. GEP-NET under 30 years best predicted a MEN1 mutation. The present study thus confirmed a previous proposal and suggested that GEP-NET under 30 years should be considered as a part of the indication criteria for MEN1 mutational analysis.

Antioxidant measurements.

Chemical reactions, including oxidation and reduction of molecules, occur in every cell. These reactions can lead to the production of free radicals. Free radicals react with organic substrates such as lipids, proteins, and DNA. Through oxidation free radicals cause damage to these molecules, disturbing their normal function, and may therefore contribute to a variety of diseases. The anti-oxidation system, which consists of enzymatic antioxidants and non-enzymatic antioxidants, defends against oxidative stress. The aim of this review is to summarize general aspects of methods to measure the antioxidant defence system all in one (total antioxidant capacity) and discuss a number of methods which are currently used for detection of antioxidant properties.

Plasma ghrelin response to an oral glucose load in growth hormone-deficient adults treated with growth hormone.

BACKGROUND: Little is known about the pathophysiology of ghrelin secretion in growth hormone-deficient adults treated with growth hormone, and the relationship between plasma ghrelin and hyperinsulinemia induced by an oral glucose load has not been investigated in these patients. OBJECTIVE: In the present study we examined the relationship between plasma ghrelin, insulin, C-peptide and leptin after an oral glucose load in growth hormone-deficient adults receiving treatment with growth hormone. METHODS: Plasma ghrelin, leptin, insulin, C-peptide and blood glucose were measured before and then at 30, 60, 90 and 120 min after the ingestion of glucose (75 g orally) in 20 growth hormone-deficient adults (12 women and 8 men), who had been treated with growth hormone for 7.2 +/- 1.3 years (mean +/- SE). Plasma ghrelin was also determined before and after the glucose load in 10 age-and weight-matched healthy persons (5 women and 5 men). RESULTS: The oral glucose load induced a similar percent suppression of plasma ghrelin in the growth hormone-deficient patients and in the healthy persons. In both groups plasma ghrelin decreased significantly 30 min after the glucose load and remained suppressed throughout the test period. In the patients plasma insulin (baseline, 15.9 +/- 3.9 microIU/ml) and C-peptide (baseline, 2.5 +/- 0.3 ng/ml) showed opposite changes with peak responses at 30 min (insulin, 109.5 +/- 15.6 microIU/ml) or 60 min (C-peptide, 10.3 +/- 1.1 ng/ml). In these patients, post-glucose, but not baseline plasma ghrelin levels correlated negatively with plasma insulin, C-peptide and blood glucose levels, whereas baseline plasma ghrelin correlated inversely with baseline plasma leptin. CONCLUSIONS: The similar suppression of plasma ghrelin in growth hormone-deficient patients treated with growth hormone and in healthy persons after an oral glucose load argues against disturbed regulation of ghrelin secretion in these patients. The correlations between post-glucose plasma ghrelin, insulin and blood glucose support the existence of a previously proposed link between hyperinsulinemia (or increased blood glucose) and suppression of ghrelin levels.

Structure-Independent Proton Transport in Cerium(III) Phosphate Nanowires.

Understanding of water-related electrical conduction is of utmost importance in applications that utilize solid-state proton conductors. However, in spite of the vast amount of theoretical and experimental work published in the literature, thus far its mechanism remained unsolved. In this study, the structure-related ambient temperature electrical conduction of one-dimensional hydrophilic nanostructures was investigated. Cerium phosphate nanowires with monoclinic and hexagonal crystal structures were synthesized via the hydrothermal and ambient temperature precipitation routes, and their structural and surface properties were examined by using high-resolution transmission electron microscopy, X-ray diffractometry, nitrogen and water sorption, temperature-programmed ammonia desorption, and potentiometric titration techniques. The relative humidity (RH)-dependent charge-transport processes of hexagonal and monoclinic nanowires were investigated by means of impedance spectroscopy and transient ionic current measurement techniques to gain insight into their atomistic level mechanism. Although considerable differences in RH-dependent conductivity were first found, the distinct characteristics collapsed into a master curve when specific surface area and acidity were taken into account, implying structure-independent proton conduction mechanism in both types of nanowires.

[Ghrelin: a new peptide regulating the neurohormonal system and energy homeostasis]. / Ghrelin: a neurohormonális rendszert es az energia egyensúlyt szabályozó uj peptid.

Ghrelin: a new peptide regulating the neurohormonal system and energy homeostasis. Research leading to the identification of ghrelin started with the discovery of growth hormone secretagogues, continued with the description of ghrelin receptors and ended with description of the chemical structure of ghrelin. However, several aspects concerning the role of ghrelin in physiology and pathophysiology are still under investigation. The majority of ghrelin is produced in the stomach, but it is also expressed in the hypothalamus, pituitary, intestine, kidney, heart, pancreas and gonads. Ghrelin stimulates growth hormone secretion via growth hormone secretagogue receptors, and it increases appetite. Ghrelin secretion in the stomach depends on both acute and chronic changes in energy balance. Presently available data support the hypothesis that the stomach, in addition to its important role in digestion, not only influences pituitary hormone secretion via ghrelin production but it also sends orexigenic (appetite increasing) signals to hypothalamic nuclei involved in the regulation of energy homeostasis. In addition to these main effects, ghrelin influences the cardiovascular, gastrointestinal, reproductive and endocrine functions. It can be anticipated that further research on the physiological and pathophysiological role of ghrelin will lead to a better understanding of neurohormonal processes and the central regulation of energy homeostasis.

Photocatalytic H2 Production Using Pt-TiO2 in the Presence of Oxalic Acid: Influence of the Noble Metal Size and the Carrier Gas Flow Rate.

The primary objective of the experiments was to investigate the differences in the photocatalytic performance when commercially available Aeroxide P25 TiO2 photocatalyst was deposited with differently sized Pt nanoparticles with identical platinum content (1 wt%). The noble metal deposition onto the TiO2 surface was achieved by in situ chemical reduction (CRIS) or by mixing chemically reduced Pt nanoparticle containing sols to the aqueous suspensions of the photocatalysts (sol-impregnated samples, CRSIM). Fine and low-scale control of the size of resulting Pt nanoparticles was obtained through variation of the trisodium citrate concentration during the syntheses. The reducing reagent was NaBH4. Photocatalytic activity of the samples and the reaction mechanism were examined during UV irradiation (λmax = 365 nm) in the presence of oxalic acid (50 mM) as a sacrificial hole scavenger component. The H2 evolution rates proved to be strongly dependent on the Pt particle size, as well as the irradiation time. A significant change of H2 formation rate during the oxalic acid transformation was observed which is unusual. It is probably regulated both by the decomposition rate of accumulated oxalic acid and the H⁺/H2 redox potential on the surface of the catalyst. The later potential is influenced by the concentration of the dissolved H2 gas in the reaction mixture.

Photocatalytic H2 Evolution Using Different Commercial TiO2 Catalysts Deposited with Finely Size-Tailored Au Nanoparticles: Critical Dependence on Au Particle Size.

One weight percent of differently sized Au nanoparticles were deposited on two commercially available TiO2 photocatalysts: Aeroxide P25 and Kronos Vlp7000. The primary objective was to investigate the influence of the noble metal particle size and the deposition method on the photocatalytic activity. The developed synthesis method involves a simple approach for the preparation of finely-tuned Au particles through variation of the concentration of the stabilizing agent. Au was deposited on the TiO2 surface by photo- or chemical reduction, using trisodium citrate as a size-tailoring agent. The Au-TiO2 composites were synthetized by in situ reduction or by mixing the titania suspension with a previously prepared gold sol. The H2 production activities of the samples were studied in aqueous TiO2 suspensions irradiated with near-UV light in the absence of dissolved O2, with oxalic acid or methanol as the sacrificial agent. The H2 evolution rates proved to be strongly dependent on Au particle size: the highest H2 production rate was achieved when the Au particles measured ~6 nm.

Diagnostic performance of salivary cortisol and serum osteocalcin measurements in patients with overt and subclinical Cushing's syndrome.

OBJECTIVE: The cut-off value for salivary cortisol measurement for the diagnosis of Cushing's syndrome (CS) may depend both on the severity of the disease and the composition of control group. Therefore, we examined the utility of midnight salivary cortisol measurements in patients who were evaluated for signs and symptoms of CS or because they had adrenal incidentalomas. Because serum osteocalcin (OC) is considered as a sensitive marker of hypercortisolism, we also investigated whether OC could have a role in the diagnosis of CS. PATIENTS AND METHODS: Each of the 151 patients was included into one of the following groups: (A) overt CS (n=23), (B) subclinical CS (n=18), (C) inactive adrenal adenomas (n=40), (D) patients without HPA disturbances (n=70). Patients (C+D) were used as controls. Serum, salivary and urinary cortisol, and OC were measured by electrochemiluminescence immunoassay. RESULTS: Group A had suppressed OC as compared to both group B and group (C+D). Serum and salivary cortisol concentrations showed strong negative correlations with OC in patients with overt CS. The areas under the curves of salivary and serum cortisol at 24:00 h (0.9790 and 0.9940, respectively) serum cortisol after low dose dexamethasone test (0.9930) and OC (0.9220) obtained from ROC analysis for the diagnosis of overt CS were not statistically different. CONCLUSION: This study confirms the usefulness of midnight salivary cortisol measurements in the diagnosis of overt CS in the everyday endocrinological praxis. Our results suggest that OC may have a role in the diagnosis of overt CS.

Rapid progression of amyotrophic lateral sclerosis in an acromegalic patient after surgical resection of a growth hormone-producing pituitary adenoma.

INTRODUCTION: Insulin-like growth factor-1 (IGF-1) promotes the survival of neurons, mediates neuritic growth, and in 1 clinical trial human recombinant IGF-1 delayed the progression of functional impairment and decline of health-related quality of life in patients with amyotrophic lateral sclerosis (ALS). CASE REPORT: We describe a case of a 65-year-old woman with a 2-year history of symptoms and signs of acromegaly because of a pituitary microadenoma. The patient posed a challenging diagnostic dilemma because of the presence of dysarthria, which was initially considered as the consequence of acromegaly. After octreotide long-acting release (LAR) treatment, the patient underwent uneventful pituitary surgery. Although postoperative evaluation indicated a cure of acromegaly, progressive bulbar symptoms developed, which were followed by upper limb weakness and muscle atrophy. Neurologic investigations confirmed the diagnosis of ALS and riluzole therapy was given. One year after surgery growth-hormone deficiency was diagnosed, but a trial with human recombinant growth hormone failed to produce any significant improvement. Two years after surgery the patient died of a sudden respiratory arrest. Histopathologic examination of the brain and spinal cord confirmed the diagnosis of ALS. CONCLUSIONS: This is the first report showing a rapid progression of ALS after a surgical cure of coexisting acromegaly presumably because of cessation of high endogenous IGF-I levels.

Ghrelin: a new peptide regulating the neurohormonal system, energy homeostasis and glucose metabolism.

Identification of ghrelin started with the discovery of growth hormone secretagogues, continued with the description of ghrelin receptors and ended with the elucidation of the chemical structure of ghrelin. However, several issues concerning the role of ghrelin in physiological and pathophysiological processes are still under investigation. Most of the ghrelin produced in the body is secreted in the stomach, but it is also expressed in the hypothalamus, pituitary, pancreas, intestine, kidney, heart and gonads. Ghrelin stimulates growth hormone secretion via growth hormone secretagogue receptors. Ghrelin secretion in the stomach depends on both acute and chronic changes in nutritional status and energy balance. Current data support the hypothesis that the stomach, in addition to its important role in digestion, not only influences pituitary hormone secretion but, via ghrelin production, it also sends orexigenic (appetite increasing) signals to hypothalamic nuclei involved in the regulation of energy homeostasis. In addition to these main effects, ghrelin influences insulin secretion and glucose metabolism and it may exert potentially important effects on cardiovascular and gastrointestinal functions. Because of its effects on a large number of physiological functions, ghrelin may be involved in the pathomechanism of several human disorders, including disturbances of appetite, energy homeostasis and glucose metabolism. Further research might lead to a better understanding of the pathophysiology of ghrelin and might provide more effective therapy for the above disorders.