bluuebunny/crossref_metadata_2025_split huggingface dataset:
The metabolism of isoforms of human adiponectin: studies in human subjects and in experimental animals
Authors: Peake Philip W , Kriketos Adamandia D , Campbell Lesley V , Shen Yvonne , Charlesworth John A 
Published: August 2005

Objective: Little is known of the metabolism of different isoforms of adiponectin. We therefore (a) characterised the size distribution of human adiponectin in relation to gender, body composition and following a challenge with a fat meal or oral glucose in humans, and (b) studied the metabolism of isoforms of human adiponectin in rabbits.Method: Electrophoresis, blotting and chromatography were used to characterise human adiponectin in 36 healthy subjects, including 15 with at least two first-degree relatives with type 2 diabetes, before and after consumption of a fatty meal or glucose. The metabolism of column-fractionated human adiponectin was studied in rabbits, some of which were coinjected with insulin.Results: Females had a higher proportion of high molecular weight (HMW) and hexameric adiponectin (P= 0.002 and 0.004 respectively), and a lower proportion of trimers (P< 0.0001) than males. Females also showed a strong negative relationship between body fat measures and the proportion of HMW adiponectin. There were no differences in isoforms between insulin-resistant and -sensitive subjects, or following oral glucose or a fat meal. Adiponectin in rabbits had an extravascular/intravascular ratio of 0.71, and a half-life (T1/2) of 14.3 h. Metabolism was not influenced by insulin or reduction of sulphydryl bonds. HMW and trimeric isoforms had a significantly different T1/2 of 13.0 and 17.5 h respectively (P< 0.05), and these isoforms did not interconvertin vivo.Conclusions: Human adiponectin is present as trimers, hexamers and HMW forms. Females had a higher proportion and absolute amount of HMW species compared with males, and female, but not male, subjects showed a strong negative relationship between measures of body fat, and the proportion of HMW species. These isoforms did not respond to challenge in man with a fatty meal or oral glucose, and in the rabbit, to injected insulin. HMW adiponectin was more rapidly metabolised than the trimeric form, but both were stablein vivo, and did not interconvert. We conclude that human adiponectin is much longer-lived than is the case with other hormones, a finding with positive implications for the potential to supplement levels of adiponectin in man.
Hypoxia-induced leptin production in human trophoblasts does not protect from apoptosis
Authors: Meißner Udo , Spranger Robert , Lehner Manfed , Allabauer Ida , Rascher Wolfgang , Dötsch Jörg 
Published: August 2005

Objective: Theob-gene product, leptin, is an important regulator of placental and fetal development during pregnancy. Leptin, being induced by hypoxia in the placenta, is a known pro-apoptotic molecule in adipose tissue but is also known to inhibit apoptosis in other tissues like neuroblastoma cells. Based on these findings, we investigated if leptin has a pro- or anti-apoptotic effect on a trophoblastic cell line (JAr cells) in the presence or absence of oxygen.Methods and results: Measurement of leptin in the supernatant by using ELISA showed hypoxia-induced leptin production in JAr cellsin vitro. This could be confirmed by a leptin-specific RT-PCR. By analyzing leptin and/or hypoxia exposed cells with FACS cytometry we found that JAr cells can cope with hypoxia down to oxygen tensions of 1%. At this level, only a small number of cells underwent apoptosis. Interestingly, leptin added to the culture medium in high concentrations was not able to interfere with the rate of proliferation or apoptosis in these cells independent of the oxygen tension. Finally, an anti-caspase-3 and anti-caspase-9 Western blot was performed. Again, no difference in the expression of caspase-3 and -9 under the conditions tested was seen.Conclusions: These results show that leptin, produced by placental cells after hypoxiain vitro, has no influence on the rate of proliferation of these cells. Furthermore, it does not influence apoptotic pathways in the trophoblastic cell line tested under hypoxic and non-hypoxic conditions.
Extended clinical phenotype, endocrine investigations and functional studies of a loss-of-function mutation A150V in the thyroid hormone specific transporter MCT8
Authors: Biebermann Heike , Ambrugger Petra , Tarnow Patrick , von Moers Arpad , Schweizer Ulrich , Grueters Annette 
Published: August 2005

Objective: Thyroid hormones, besides having other functions, are known to be essential for the development of the human brain. Recently the monocarboxylate transporter 8 (MCT8) was identified as a thyroid hormone transporter which is expressed in different regions of the human brain. Here we describe in detail the clinical and biochemical features in response to thyroid hormone administration of a boy carrying an MCT8 mutation (A150V) in the second transmembrane domain.
Methods: To study the functional impact of the mutation we performed triiodothyronine (T3) uptake, immunofluorescence and dimerization studies.
Results: Thyroid hormone (l-thyroxine (LT4) and LT3) administration did not result in any significant clinical changes; however, with high doses of LT4, alone or in combination with T3, TSH suppression was achieved. We could show a robust uptake of 125I-T3 for wild type (WT) MCT8, whereas no specific uptake could be detected for the mutant A150V. Subcellular localization of WT and mutant MCT8 revealed a strong cell surface expression for the WT MCT8, in contrast to A150V, which is mostly retained intracellularly with only weak cell surface expression. We could also demonstrate for the first time that WT MCT8 as well as the mutant are able to form multimers.
Conclusion: Our findings open a wide field of possible interaction within the central nervous system and will help to understand the crucial role of MCT8 in early fetal brain development.
Glucagon inhibits ghrelin secretion in humans
Authors: Arafat M A , Otto B , Rochlitz H , Tschöp M , Bähr V , Möhlig M , Diederich S , Spranger J , Pfeiffer A F H 
Published: August 2005

Objective: It is well known that i.m. glucagon administration stimulates GH and cortisol release in humans, although the mechanisms are unclear. These effects are similar to those described for ghrelin on somatotroph and corticotroph function. The aim of the present study was to investigate the role of ghrelin in mediating the stimulatory effects of glucagon and to evaluate the effect of glucagon on ghrelin secretion.
Design and methods: We studied the endocrine and metabolic response to i.m. glucagon administration in 24 subjects (14 men, 10 women; age 19–65 years; body mass index, 25.3 ± 1 kg/m2), who were shown to have an intact anterior pituitary function as evaluated before enclosure.
Results: Serum ghrelin concentrations fell significantly at 30, 60, 120 and 180 min after glucagon administration (means ± s.e.m.; baseline, 377.9 ± 34.5 pg/ml; nadir, 294.6 ± 28.3 pg/ml (60 min); P < 0.01). Conversely, i.m. glucagon elicited an increase in GH (baseline, 1.5 ± 0.4 μg/l; peak, 14.2 ± 2.7 μg/l (180 min); P < 0.01) and cortisol concentrations (baseline, 452.6 ± 35.2 nmol/l; peak, 622.1 ± 44 nmol/l (180 min); P < 0.01). The changes in ghrelin concentration at both 120 and 180 min were still significant after correction for glucose and insulin (P < 0.05).
Conclusions: We show that i.m. glucagon decreases ghrelin significantly. Therefore, the already known stimulatory effects of i.m. glucagon on cortisol and GH are not mediated by a change in ghrelin concentrations. The mechanisms underlying the ghrelin suppression after i.m. glucagon are unlikely to include glucose or insulin variations and need to be further elucidated.
Xenotransplantation of porcine neonatal islets of Langerhans and Sertoli cells: a 4-year study
Authors: Valdés-González Rafael A , Dorantes Luis M , Garibay G Nayely , Bracho-Blanchet Eduardo , Mendez Armando J , Dávila-Pérez Roberto , Elliott Robert B , Terán Luis , White David J G 
Published: August 2005

Objective: Porcine islets of Langerhans for xenotransplantation into humans have been proposed as a solution to the shortage of human donors. Rejection is one of the main constraints. This study presents the results of a clinical trial using a novel method for transplanting and immunoprotecting porcine islets in type 1 diabetic patients.Design: A 4-year follow up of a clinical trial involving 12 patients, with no immunosuppressive drugs at any point. Eleven age matched untransplanted diabetics served as controls.Methods: We have developed a procedure for protecting neonatal porcine islets by combining them with Sertoli cells and placing them in a novel subcutaneous autologous collagen-covered device.Results: In the patients in the treatment group, no complications arose and no porcine endogenous retrovirus infection was detected. Half of the patients showed a significant reduction in insulin requirements compared with both their pre transplant levels and controls, and this reduction was maintained for up to 4 years. Two patients became insulin-independent for several months. Porcine insulin was detected in three patients’ sera following glucose stimulation up to 4 years post transplant. Three years post transplant, one of four devices was removed from four patients, and the presence of insulin-positive cells in the transplant was demonstrated by immunohistology in all 4 patients.Conclusions: Long-term cell survival with concurrent positive effects on metabolic control are possible by this technique.
Inhibition of pituitary type 2 deiodinase by reverse triiodothyronine does not alter thyroxine-induced inhibition of thyrotropin secretion in hypothyroid rats
Authors: Cettour-Rose P , Visser T J , Burger A G , Rohner-Jeanrenaud F 
Published: August 2005

Objectives: Intrapituitary triiodothyronine (T3) production plays a pivotal role in the control of TSH secretion. Its production is increased in the presence of decreased serum thyroxine (T4) concentrations and the enzyme responsible, deiodinase type 2 (D2), is highest in hypothyroidism. In order to document the role of this enzyme in adult rats we developed an experimental model that inhibited this enzyme using the specific inhibitor, reverse T3 (rT3).
Methods: Hypothyroidism was induced with propylthiouracil (PTU; 0.025 g/l in drinking water) which in addition blocked deiodinase type 1 (D1) activity, responsible for the rapid clearance of rT3 in vivo. During the last 7 days of the experiment, the hypothyroid rats were injected (s.c.) for 4 days with 0.4 or 0.8 nmol T4 per 100 g body weight (bw) per day. For the last 3 days, the same amount of T4 was infused via s.c. minipumps. In additional groups, 25 nmol rT3/100 g bw per day were added to the 3-day infusion of T4.
Results: Infusion of 0.4 nmol T4/100 g bw per day did not affect the high serum TSH levels, 0.8 nmol T4/100 g bw per day decreased them to 57% of the hypothyroid values. The infusions of rT3 inhibited D2 activity in all organs where it was measured: the pituitary, brain cortex and brown adipose tissue (BAT). In the pituitary, the activity was 27%, to less than 15% of the activity in hypothyroidism. Despite that, serum TSH levels did not increase, serum T4 concentrations did not change and the changes in serum T3 were minimal.
Conclusions: We conclude that in partly hypothyroid rats, a 3-day inhibition of D2 activity, without concomitant change in serum T4 and minimal changes in serum T3 levels, is not able to upregulate TSH secretion and we postulate that this may be a reflection of absent or only minimal changes in circulating T3 concentrations.
The threshold of bone mineral density for vertebral fractures in female patients with primary hyperparathyroidism
Authors: Kaji Hiroshi , Yamauchi Mika , Chihara Kazuo , Sugimoto Toshitsugu 
Published: August 2005

Background and objective: Primary hyperparathyroidism (pHPT) is one of the causal diseases that induce secondary osteoporosis. Although patients with pHPT have reduced bone mineral density (BMD) especially at the cortical bone, there have been controversies about risk of fracture. Moreover, no reports have been available about the threshold of BMD for fractures in pHPT patients.Methods: BMD values were measured by dual-energy x-ray absorptiometry at lumbar spine, femoral neck and distal one third of radius. Various indices were compared in 116 female pHPT patients and 716 control subjects. Moreover, we analyzed relationship between the cut-off values of BMD and the prevalence of vertebral fractures in pHPT and control subjects.Results: The prevalence of subjects with vertebral fractures was lower in pHPT patients, compared with that of control subjects. Age and body height were significantly higher and lower in pHPT women with vertebral fractures, respectively. Lumbar spine BMD was significantly lower in pHPT women with vertebral fractures, presumably due to their increased age. There were no differences in femoral neck and radius BMD or in bone metabolic indices between pHPT women with and without vertebral fractures. On the other hand, age-matched BMD was not significantly different between both groups at any measured site. Cut-off values of BMD at lumbar spine and femoral neck were lower in postmenopausal pHPT patients, compared with those of the postmenopausal control group. Moreover, cut-off values of BMD at radius was much lower in postmenopausal pHPT patients, compared with those of the postmenopausal control group (pHPT vs control (g/cm2): 0.670 vs 0.706 at lumbar spine; 0.549 vs 0.570 at femoral; 0.394 vs 0.474 at radius). Sensitivity and specificity of vertebral fractures was lower in pHPT patients, compared with those in control group.Conclusions: The present cross-sectional study demonstrated that thresholds of BMD for vertebral fractures were lower especially at radial bone in female patients with pHPT, compared with those in the control group.
Auxological and endocrine phenotype in a population-based cohort of patients with PROP1 gene defects
Authors: Lebl Jan , Vosáhlo Jan , Pfaeffle Roland W , Stobbe Heike , Černá Jana , Novotná Dana , Zapletalová Jiřina , Kalvachová Božena , Hána Václav , Weiss Vladimír , Blum Werner F 
Published: August 2005

Objective: Multiple pituitary hormone deficiency (MPHD) may result from defects of transcription factors that govern early pituitary development. We aimed to establish the prevalence of HESX1, PROP1, and POU1F1 gene defects in a population-based cohort of patients with MPHD and to analyse the phenotype of affected individuals.
Design and methods: Genomic analysis was carried out on 74 children and adults with MPHD from the Czech Republic (including four sibling pairs). Phenotypic data were collected from medical records and referring physicians.
Results: One patient carried a heterozygous mutation of POU1F1 (71C > T), and 18 patients (including three sibling pairs) had a PROP1 mutation (genotypes 150delA/301delGA/9/, 301delGA/301-delGA/8/, or 301delGA/349T > A/1/). A detailed longitudinal phenotypic analysis was performed for patients with PROP1 mutations (n = 17). The mean ( ±s.d.) birth length SDS of these patients (0.12 ± 0.76) was lower than expected based on their mean ( ±s.d.) birth weight SDS (0.63 ± 1.27; P = 0.01). Parental heights were normal. The patients’ mean ( ±s.d.) height SDS declined to −1.5 ± 0.9, −3.6 ± 1.3 and −4.1 ± 1.2 at 1.5, 3 and 5 years of age, respectively. GH therapy, initiated at 6.8 ± 3.2 years of age (mean dose: 0.022 mg/kg per day), led to substantial growth acceleration in all patients. Mean adult height (n = 7) was normal when adjusted for mid-parental height. ACTH deficiency developed in two out of seven young adult patients.
Conclusions: PROP1 defects are a prevalent cause of MPHD. We suggest that testing for PROP1 mutations in patients with MPHD might become standard practice in order to predict risk of additional pituitary hormone deficiencies.
Silicate layer dispersion in copolymer/clay nanocomposites
Authors: Hasegawa Naoki , Tsukigase Azusa , Usuki Arimitsu 
Published: August 2005

AbstractFactors of silicate layer dispersions in polymers have been studied with copolymers. The influence of the copolymerization ratio of copolymers and the alkyl chain lengths of organomodified reagents of organophilic clay has been examined. The dispersion of silicate layers in copolymers is dependent on the copolymerization ratios of the functional groups, that is, the polarity of the polymer matrix. The alkyl chain lengths of organomodified reagents also have an important influence on silicate layer dispersions. From a comprehensive viewpoint, the polarity matching between polymers and organophilic clay is an important factor for silicate layer dispersions in polymers. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1554–1557, 2005
Comparison of morphology and properties of polyelectrolyte complex particles formed from chitosan and polyanionic biopolymers
Authors: Barck Karolina , Butler Michael F. 
Published: August 2005

AbstractBeads containing a chitosan core and a polyelectrolyte complex (PEC) shell were formed by the dropwise addition of chitosan to solutions containing sodium alginate, gellan, pectin, κ‐carrageenan, or poly(acrylic acid). Hydrogel cores were formed by crosslinking chitosan with genipin, a natural bifunctional crosslinker. The shell thickness was generally only a few molecules thick and was impermeable to the transport of macromolecules but not low molecular weight molecules. Increasing the number of anionic groups and the strength of the chitosan–polyanion interaction through selection of different anionic species increased the mechanical strength of the PEC shell by increasing the number of interaction points in the shell. Because the core and shell swelled differentially, with the shell able to swell much less than the core, increasing the shell strength increasingly constrained the degree of swelling that could be attained for the entire bead. The degree of swelling could therefore be controlled via the mechanical properties of the shell, which could in turn be explained by the molecular structure of the PEC shell. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1581–1593, 2005
Conductivity of polyolefins filled with high‐structure carbon black
Authors: Yu J. , Zhang L. Q. , Rogunova M. , Summers J. , Hiltner A. , Baer E. 
Published: August 2005

AbstractThe electrical conductivities of various polyolefins filled with a high‐structure carbon black (CB) were studied. Typical percolation behaviors were observed in all of the materials studied. At a critical CB content, which defined the percolation threshold, CB formed conductivity pathways, and resistivity fell sharply from a value characteristic of an insulator into the range of 10–100 Ω cm. The dependence of the percolation threshold on the matrix viscosity was understood in terms of competing effects on CB dispersion during blending and CB flocculation during compression molding. For the conditions used in this study, polypropylene with a melt flow index of about 50 was optimum. Flocculation in the quiescent melt was studied directly by atomic force microscopy. Conductivity pathways formed over time by CB agglomeration. The temperature dependence of the percolation time was described by an Arrhenius relationship. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1799–1805, 2005
Substitution effects of methyl and trifluoromethyl groups on the physicochemical properties of epoxy resins
Authors: Lee Jae‐Rock , Jin Fan‐Long , Park Soo‐Jin 
Published: August 2005

AbstractWe studied the effects of functional groups on the physicochemical properties, such as rheological behavior, thermal stability, glass‐transition temperature, and electrical and mechanical properties, of 4,4′‐diaminodiphenyl methane (DDM) cured methyl‐substituted and trifluoromethyl‐substituted difunctional epoxy resins [i.e., 2‐diglycidylether of toluene (DGET) and 2‐diglycidylether of benzotrifluoride (DGEBTF)]. The DGEBTF/DDM system showed higher thermal stability and lower dielectric constant values than the DGET/DDM system. The impact strength of the DGEBTF/DDM system was significantly higher than that of the DGET/DDM system. The increase in intermolecular interactions because of the increasing polarity of the fluorine in the epoxy backbone was probably the key to these results. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1860–1864, 2005
Poly(butylene succinate)/twice functionalized organoclay nanocomposites: Preparation, characterization, and properties
Authors: Chen Guang‐Xin , Kim Eung‐Soo , Yoon Jin‐San 
Published: August 2005

AbstractA new method was attempted to improve the interaction between poly(butylene succinate) (PBS) and a commercially available organoclay, Cloisite 25A (C25A), by the addition of epoxy groups to the clay. Epoxy groups were grafted to C25A by a treatment with (glycidoxypropyl)trimethoxy silane to produce twice functionalized organoclay (TFC). Tethering PBS molecules to the epoxy groups on the surface of TFC was attempted through melt compounding. The morphological structure of the composites was analyzed with X‐ray diffractometry and transmission electron microscopy. The higher degree of exfoliation of the silicate layers in PBS/TFC and the improved mechanical properties, in comparison with those of PBS/C25A, were attributed to the increased interfacial interaction between PBS and TFC. TFC accelerated the crystallization of PBS more effectively than C25A, and this indicated that TFC was more efficacious for the nucleation than C25A. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1727–1732, 2005
Synthesis of polyurethane acrylates by hydrogenated castor oil and dimer‐based polyester diol and study on pressure‐sensitive adhesive
Authors: Ren Yaobin , Pan Huiming , Li Longsi , Xia Jianming , Yang Yongqiang 
Published: August 2005

AbstractSynthesis of polyurethane acrylate (PUA) and preparation of the UV‐cured pressure‐sensitive adhesives (PSA) are reported. Molecular weight (Mw) (by gel permeation chromatography) and viscosity (η*) of PUA were measured. Characterization of PUA and PSA before and after UV‐curing was made by FTIR. Increase of the hydroxyls from hydrogenated castor oil/hydroxyls from dimer‐based polyester diol (OHHCO/OHDiol) ratio decreased the Mw and η* value of PUA. Dynamic viscoelastic properties (by dynamic rheological spectrometer) and performance of the UV‐cured PSA were also studied. Increase of the OHHCO/OHDiol ratio increased the storage modulus (G′), the loss modulus (G″), and complex viscosity (Eta*) of the UV‐cured PSA, which, in turn, enhanced holding power and shear adhesion failure temperature (SAFT) and yet decreased peeling strength. Substitution of OB for DBTDL depressed the Mw and η* value of PUA, while the G″ and Eta* values of the UV‐cured PSA were elevated, which, in turn, increased the holding power and SAFT and yet depressed the peeling strength. Elevation of the tackifying resin content depressed the G′, G″, and Eta* values of the cured PSA and yet increased glass transition temperatures (Tg) of PSA, measured by differential scanning calorimetry. Peeling strength of PSA elevated as increasing the tackifying resin, while the holding power and SAFT fell. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1814–1821, 2005