bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression pattern of tumour necrosis factor receptors in subcutaneous and omental human adipose tissue: role of obesity and non‐insulin‐dependent diabetes mellitus
Authors: Hube  , Birgel  , Lee  , Hauner
Published: March 2003

Background

Tumour necrosis factor α (TNF) mRNA expression has been reported to be up‐regulated in adipose tissue from several rodent models of obesity and diabetes and from obese humans. This elevated expression has been assumed to be associated with the development of insulin resistance. However, the biological signal of TNF may be influenced by the expression of the two TNF receptors: the p60 TNF receptor, TNFR60, and the p80 TNF receptor, TNFR80.

Design

The aim of this study was to investigate the mRNA expression pattern of the two TNF receptors and their ligand in two adipose tissue depots of glucose‐tolerant obese women [n = 18, body mass index (BMI) 48.2 ± 8.4 kg m−2], obese women with impaired glucose tolerance or overt non‐insulin‐dependent diabetes mellitus (NIDDM) (n = 10, BMI 49.1 ± 11.6 kg m−2) and healthy non‐obese control subjects (n = 12, BMI 25.8 ± 2.7 kg m−2). RNA expression was assessed by a semiquantitative reverse transcriptase polymerase chain reaction (RT‐PCR) technique.

Results

The mean mRNA levels of both TNF receptors were two‐ to threefold higher in adipose tissue samples from the obese than from the non‐obese women (P < 0.01 for each). Although TNFR60 mRNA did not vary within each obese group, there was a wide variation in the levels of TNFR80 mRNA and of TNF mRNA. A comparison of the expression levels between the subcutaneous abdominal and the omental adipose tissue depots showed significantly higher expression in the former. The TNFR60 expression level was positively correlated with BMI and fat cell size, whereas TNFR80 and TNF mRNA levels showed positive associations with serum insulin and triglyceride concentrations. No significant differences in the expression levels were observed between obese individuals with and without impaired glucose tolerance/NIDDM.

Conclusion

These results indicate that severe obesity in women is characterized by increased amounts of the two TNF receptor mRNAs. The role of this up‐regulation for the development of obesity‐associated insulin resistance remains to be elucidated.
Anti‐PR‐3 antibodies induce endothelial IL‐8 release
Authors: Mayet  , Schwarting  , Barreiros  , Schlaak  , Neurath
Published: March 2003

Background

It has been shown that interaction of anti‐PR‐3 antibodies with human endothelial cells (EC) leads to an activation of EC in vitro, i.e. induction of adhesion molecules like E‐selectin, VCAM‐1 and tissue factor. The aim of this study was to investigate the effect of anti‐PR‐3 antibodies on endothelial IL‐8 expression.

Materials and methods

EC were cultured in 96‐well plates and stimulated with TNF‐α and IL‐1β for 1 h to induce membrane expression of endothelial PR‐3. Anti‐PR‐3 antibodies were purified from sera from patients with clinically active Wegener's granulomatosis. Purified anti‐Ro, anti‐centromere, anti‐dsDNA antibodies and a monoclonal anti‐PR‐3 antibody (WGM2) served as controls. Induction of IL‐8 mRNA was detected by RT‐PCR. IL‐8 was measured in the supernatant of EC by ELISA. In addition, induction of NFκB was investigated by PAGE of nuclear extracts of EC and Western blot with ab against p65.

Results

In contrast to controls, interaction of anti‐PR‐3 antibodies (patients and WGM2) with cytokine activated EC led to the highest amount of IL‐8 synthesis. Priming of EC with cytokines alone induced a markedly lower IL‐8 level. The lowest levels of IL‐8 could be measured after incubation of unprimed EC with anti‐PR‐3 antibodies. Anti‐PR‐3 antibody induced endothelial IL‐8 expression could be inhibited by cycloheximide. In addition, we established that the activation of NF‐κB is critically involved in anti‐PR‐3 antibody induced endothelial IL‐8 production.

Conclusion

In summary, we were able to show that anti‐PR‐3 antibodies induce endothelial IL‐8 synthesis by activating NF‐κB. As IL‐8 represents a powerful neutrophil chemoattractant, our data provide further evidence for a direct pathogenic effect of anti‐PR‐3 antibodies in ANCA related diseases.
Compound heterozygosity of Leu252Val and Leu252Arg causing lipoprotein lipase deficiency in a Chinese patient with hypertriglyceridemia
Authors: Chan  , Mak  , Tomlinson  , Baum  , Wu  , Masarei  , Pang
Published: March 2003

Background

We investigated lipoprotein lipase (LPL) gene mutations in a Chinese male with severe hypertriglyceridemia and recurrent pancreatitis.

Methods

We screened for LPL sequence mutation in the LPL gene in this patient, his relatives and 160 unrelated hypertriglyceridaemic subjects. We determined the postheparin plasma LPL activity of subjects carrying a LPL mutation and studied the in vitro expression of mutant LPL in COS‐1 cells.

Results

The proband was found to be a compound heterozygote for a novel Leu252Val and a reported Leu252Arg mutation in the LPL gene. He had low plasma levels of postheparin LPL activity and mass. The two mutations segregated independently in his family. In vitro expression analysis showed that Leu252Arg abolished both the catalytic function and secretion of LPL, while Leu252Val abolished the catalytic function but only reduced secretion by about half. We have also detected heterozygous Leu252Val and Leu252Arg mutations each in one hypertriglyceridaemic individual.

Conclusion

These results indicated that the leucine 252 is critical for the catalytic activity and secretion of LPL. Why the substitution by valine instead of arginine resulted only in a partial suppression of LPL secretion, remains to be investigated. Leu252Val and Leu252Arg are the likely cause of hypertriglyceridemia in these subjects because of their deleterious effects on LPL activity or secretion. Leu252Val/Leu252Arg is the first compound heterozygous mutation known to occur in the same codon of the LPL gene. So far they are found only in Chinese.
Effect of transdermal nitroglycerin on glucose‐stimulated insulin release in healthy male volunteers
Authors: Kovacs  , Szilvassy  , Hegyi  , Nemeth  , Ferdinandy  , Tosaki
Published: March 2003

Background

Morpholinosydnonimine, a nitric oxide (NO) donor, has been reported to inhibit insulin release in isolated pancreatic islets. We studied whether transdermal application of nitroglycerin, another NO donor widely used for angina prophylaxis, influenced glucose‐stimulated insulin release in healthy, young, male volunteers.

Methods and results

Oral glucose tolerance tests [(OGTT) 75 g glucose in 200 mL of water) were performed in the presence of placebo patches or nitroglycerin‐releasing ‘active’ patches (approx. 0.4 mg hour−1 nitroglycerin) in the same patients with a 2‐week intertest interval. Venous blood samples were taken before and 15, 30, 60, 90, 120 and 180 min after the glucose load and evaluated for plasma glucose level and immunoreactive insulin responses (radioimmunoassay). Glucose‐stimulated maximum increase in plasma insulin immunoreactivity were 36.3 ± 5 and 78.8 ± 6.1 mU mL−1 (P < 0.05) in the presence of active and placebo patches, respectively. Nevertheless, both fasting and postload blood glucose levels were the same at either patch. Active patches significantly decreased blood pressure with a marginal increase in heart rate.

Conclusion

We conclude that inhibition of glucose‐stimulated insulin release by transdermal nitroglycerin without causing hyperglycaemia may serve as a novel component of the antianginal mechanism of action of nitrates.
Assessment of bilirubin toxicity to erythrocytes. Implication in neonatal jaundice management
Authors: Brito  , Silva  , Tiribelli  , Brites
Published: March 2003

Background

Neonatal hyperbilirubinaemia remains one of the most common clinical conditions requiring therapeutic intervention. Nevertheless, reliable indicators of bilirubin toxicity are still missing. This prompted us to investigate (a) the progression of cytotoxic events produced by increasing concentrations of bilirubin; (b) the relevance of the membrane lipid package on bilirubin binding to erythrocytes; and (c) the reliability of chloroform extraction compared with albumin extraction to evaluate erythrocyte‐bound bilirubin and cytotoxicity.

Materials and methods

Morphological alterations, free bilirubin, erythrocyte‐bound bilirubin (albumin‐ and chloroform‐extractable), haemolysis and membrane‐released lipids, were determined in human erythrocytes at 4 °C or 37 °C, after 4 h incubation at pH 7.4, with increasing molar ratios of bilirubin to albumin (0.5–5). The reversibility of cytotoxicity by albumin washing was assessed by morphological analysis.

Results

Decreased free bilirubin, lower erythrocyte‐bound bilirubin concentration by albumin extraction (superficial/non‐aggregated bilirubin) and higher values by chloroform extraction (deep/aggregated bilirubin) were observed for 37 °C vs. 4 °C, at molar ratios > 1. Echinocytosis increased with bilirubin concentration and temperature and was not fully reversed by albumin washing. Haemolysis was already significant at a molar ratio of 1, and was enhanced by temperature at molar ratios 3 and 5 (P < 0.01). The loss of membrane lipids was remarkable at molar ratios ≥ 0.5, both at 4 °C and 37 °C (P < 0.01), although correlation with bilirubin concentration was only significant at 37 °C (r = 0.971; P < 0.01).

Conclusions

These results suggest that increased lipid fluidity and high bilirubin concentrations promote membrane bilirubin translocation and toxicity. They also show that albumin is not able to displace the bilirubin located deeply or aggregated within the membrane, which in turn is removed by chloroform. Accordingly, chloroform‐extractable rather than albumin‐extractable bilirubin is a more accurate parameter to assess erythrocyte‐bound bilirubin during severe hyperbilirubinaemia.
Iron supplementation affects the production of pro‐inflammatory cytokines in IL‐10 deficient mice
Authors: Oldenburg  , Van Berge Henegouwen  , Rennick  , Van Asbeck  , Koningsberger
Published: March 2003

Background

Iron supplements may increase disease activity in inflammatory bowel disease through the production of the hydroxyl radical because of its catalytic activity in the Fenton reaction. The purpose of this study was to assess the effect of dietary and locally administered iron in the IL‐10 knock‐out (−/−) mouse, a model of chronic inflammatory bowel disease.

Materials and methods

IL10−/− and wild‐type mice received a standard or a high‐iron diet (35 mg kg−1 ferrosulphate vs. 500 mg kg−1 ferrosulphate) after weaning. After 4 weeks the mice were sacrificed. Furthermore, a group of adult IL‐10 knock‐out mice was given three iron‐containing enema's (0.2 mL of 1 m
m ferrous‐ammonium sulphate) or phosphate buffered saline. These mice were sacrificed after 1 week. Production of pro‐inflammatory cytokines by colon tissue cultures, haematological parameters and histology was determined to assess inflammatory activity.

Results

Oral as well as rectal administration of iron resulted in increased pro‐inflammatory cytokine production in IL‐10−/− mice. Neutrophil counts in IL10−/− on a high iron diet increased as well. No enhanced colonic inflammation was noted on histology after iron supplementation.

Conclusion

We conclude that dietary or topical administered iron increases pro‐inflammatory cytokine production in the colon of IL10−/− mice. No significant increase of histological intestinal inflammation was observed.
Immortalisation of human bone marrow endothelial cells: characterisation of new cell lines
Authors: Rood  , Calafat  , Kr. Von dem Borne  , Gerritsen  , Van Der Schoot
Published: March 2003

Background

Adhesion of haematopoietic progenitor cells (HPC) to human bone marrow endothelial cells (HBMEC) plays a key role in homing of HPC to bone marrow. Here we describe four new HBMEC cell lines that can be used to study the (specific) adhesion of HPC to HBMEC.

Design

HBMEC were immortalised with a retroviral construct containing the human papilloma virus 16 E6/E7 genes. Four cell lines were characterised.

Results

The cell lines showed their endothelial nature by the expression of von Willebrand Factor and VE‐cadherin (CD144). Electron microscopic analysis revealed normal endothelial‐cell characteristics, including the presence of Weibel‐Palade bodies and intercellular junction structures. An extensive phenotypic analysis of the cell‐lines was performed, they were found to resemble primary HBMEC. The only difference found was the absence of expression of E‐selectin (CD62e) and VCAM‐1 (CD106) on resting HBMEC cell lines. Upon stimulation with IL‐1β the expression of E‐selectin, VCAM‐1 and ICAM‐1 (CD54) was upregulated. All resting cell lines bound CD34+ HPC. Adhesion was increased by addition of the phorbol ester PMA. Two cell lines showed increased binding upon IL‐1β prestimulation. Highest adhesion was observed after the combination of IL‐1β prestimulation of the endothelial cells and addition of PMA. Binding of CD34+ HPC to HBMEC was compared with the binding to human umbilical vein endothelial cell lines and to a human dermal microvascular endothelial cell line (HMEC‐1). So far, we have only found relatively less binding of HPC to IL‐1β prestimulated HMEC‐1 cells, which could be explained by a reduced induction of E‐selectin and VCAM‐1 upon IL‐1β stimulation of these cells.

Conclusion

The immortalised HBMEC cell lines have maintained their normal phenotype for the majority of characteristics examined. The expression of E‐selectin and VCAM‐1, which are not constitutively expressed on the cell lines, can be induced by stimulation of the endothelial cells with IL‐1β. The cell lines have furthermore maintained their capability to bind HPC. They will therefore be useful to investigate the interactions between HPC and HBMEC involved in homing of HPC.
Amelioration of hyperglycemic and hyperosmotic induced vascular dysfunction by in vivo inhibition of protein kinase C and p38 MAP kinase pathway in the rat mesenteric microcirculation
Authors: Schäffler  , Arndt  , Schölmerich  , Palitzsch
Published: March 2003

Background

Recently, we demonstrated in vivo effects of acutely induced hyperglycemia, diabetes and mannitol infusions on rat mesenteric microcirculation concerning leukocyte–endothelial‐cell interaction (Schäffler et al. EJCI 28: 886–893, 1998).

Design

In this study we have investigated the possible involvement of the protein kinase C (PKC) and p38 MAP kinase cascade as signal transducing elements during hyperglycemic and osmotic stress in an in vivo rat model.

Results

Acutely induced hyperglycemia resulted in a significant increase in leukocyte adhesion. This effect could be mimicked by mannitol. Both PKC and p38 MAP kinase were involved in the effects mediated by glucose and mannitol. Acutely induced hyperglycemia resulted in a significant increase in leukocyte emigration. This effect could be imitated by mannitol. However, PKC and p38 MAP kinase were only involved under osmotic stimulation. The hyperglycemia‐induced reduction in leukocyte rolling velocity seemed to be a glucose‐specific effect, since mannitol did not influence leukocyte rolling velocity. This glucose effect on leukocyte rolling velocity was mediated by an activation of the PKC/p38 MAP kinase cascade. Both hyperglycemia and osmotic stimuli alone were able to reduce venular shear rate without recruitment of the p38 MAP kinase cascade. The observed reduction of shear rate seems to be mediated only by the osmotic effects of glucose via activation of the PKC system.

Conclusion

The observed effects of glucose on adhesion, emigration and shear rate are due to osmotic effects. The PKC/MAP kinase cascade is involved as a signal transducing component. The reduction of leukocyte rolling velocity is a glucose‐specific effect, mediated by the activation of both the PKC and the p38 MAP kinase cascade. Venular shear rate and leukocyte emigration can be influenced by glucose and mannitol due to different regulation mechanisms. It is concluded, that isoform‐specific inhibitors of PKC and specific MAP kinase inhibitors represent a potential drug target for preventing microvascular dysfunction in diabetes.
A β‐turn rich oats peptide as an antigen in an ELISA method for the screening of coeliac disease in a paediatric population
Authors: Ribes‐Koninckx  , Alfonso  , Ortigosa  , Escobar  , Suárez  , Arranz  , Méndez
Published: March 2003

Background

ELISA methods for the measurement of IgA antigliadin antibodies (AGA), both home‐made and commercial systems, routinely employ wheat gliadin fractions as coating antigens. We investigate the sensitivity and specificity for CD diagnosis of a new ELISA method using a highly immunoreactive β‐turn rich γ3‐avenin peptide as an alternative coating antigen.

Methods

The assay was standardized with antihuman IgA peroxidase‐conjugated as the second antibody. Alternatively, an ELISA based on the use of protein A‐peroxidase was assayed to measure both IgG plus IgA antibodies. Sixty‐three sera from healthy controls were analized to establish the system's cut‐off point. Sera from 103 coeliac and from 65 noncoeliac children were tested; for diagnosis purposes, a small intestinal biopsy had been performed in all of them.

Results

For the IgA class antibodies assay a high sensitivity and specificity of 90.3% and 98.5%, respectively, was obtained, comparable to those achieved for IgA antiendomysium antibodies (EmA) with the same sera.

Conclusions

In view of the high sensitivity and specificity obtained together with water solubility of the peptide and easiness for large‐scale reproducible synthesis, the new AGA IgA avenin peptide ELISA represents a significant improvement in CD diagnosis in comparison with conventional established AGA IgA ELISA using crude gliadins as coating antigens.
The noradrenaline plasma concentration and its gradient across the lung
Authors: Marenzi  , Agostoni  , Guazzi  , Lauri  , Assanelli  , Guazzi
Published: March 2003

Background

We investigated the lung contribution to circulating noradrenaline (NA) homeostasis. Evaluation of the transpulmonary NA gradient, related to the NA amount entering the lungs, is potentially important, mainly regarding clinical conditions, such as congestive heart failure (CHF), that are associated with excessive circulating NA.

Materials and methods

15 moderate (group 1) and 15 severe (group 2) CHF patients, and 10 normal individuals had determination of NA transpulmonary gradient in the baseline and during rise (exercise, in normals and group 1) or fall (withdrawal from plasma by ultrafiltration, in group 2) of plasma NA.

Results

NA gradient (pg mL−1) at rest was 30 ± 3 in normals, 21 ± 6 in group 1 and 5 ± 8 in group 2. Increase of NA concentration in the mixed venous blood with exercise was paralleled by depression of the transpulmonary gradient. Pulmonary arteriovenous difference disappeared when NA entering the lungs averaged 1300 pg mL−1. In group 2, ultrafiltration lowered NA in the mixed venous blood from 1225 ± 213 to 718 ± 182, which caused transpulmonary gradient to increase from 5 ± 8 to 22 ± 9.

Conclusions

Transpulmonary gradient of NA diminishes when NA entering the lungs increases, and 1300 pg mL−1 in the pulmonary artery is, both in patients and normal subjects, the level at which gradient disappears; which likely reflects cessation of NA uptake or achievement of a balance between lung uptake and production. This may have physiological and pathological implications.
Elevated serum dipeptidyl peptidase IV (CD26, EC 3.4.14.5) activity in experimental liver cirrhosis
Authors: Lakatos  , Firneisz  , Borcsiczky  , Zalatnai  , Selmeci  , Szalay
Published: March 2003

Background

Dipeptidyl peptidase IV (DPP IV) is a cell surface ectoenzyme widely distributed in the rat body, present on the epithelial cells of the brush border membranes (e.g. bile canaliculi) and on the surface of reactive lymphocytes and fibroblasts. DPP IV has been implicated in hepatocyte–extracellular matrix interactions, fibroblast activation and proliferation and in T‐cell activation. Aberrant DPP IV expression was found in human liver cirrhosis, and elevated serum DPP IV activity was reported in patients with primary biliary cirrhosis and chronic hepatitis C virus infection. The aim of the study was to examine serum DPP IV activity in experimental liver cirrhosis.

Methods

Liver cirrhosis was induced by administering diethyl‐nitrosamine, phenobarbital and CCl4 in Fischer‐344 male rats (n = 22). Phenobarbital‐treated (n = 9) and nontreated (n = 9) male rats were used as controls. Serum DPP IV activity was measured using a microplate‐based continuous‐monitoring assay. Recombinant rat DPP IV was used as standard and Gly‐Pro‐PNA was used as substrate. Enzyme activity was given in nmol mL−1 min−1 (U L−1).

Results

Significantly higher DPP IV activity was found in the sera of rats with experimental liver cirrhosis (39.2 ± 3.7; mean ± SD) compared to phenobarbital‐treated (11 ± 4, P < 0.000002) and nontreated (10.9 ± 0.9, P < 0.000002) rats. There was a positive correlation between DPP IV activity and concentrations of aspartate aminotransferase (r = 0.73, P = 0.0001) and alanine aminotransferase (r = 0.69, P = 0.0004).

Conclusions

The significantly higher serum DPP IV activity found in experimental liver cirrhosis is in concordance with human observations. The elevation was probably not due to the enzyme induction effect of phenobarbital. In this experimental model, serum DPP IV seems to be an indicator for chronic liver injury.
Biliary lipid composition in patients with cholesterol and pigment gallstones and gallstone‐free subjects: deoxycholic acid does not contribute to formation of cholesterol gallstones
Authors: Gustafsson U. , Sahlin S. , Einarsson C.
Published: March 2003

Four main disturbances have been attributed to cholesterol gallstone disease: hypersecretion of cholesterol from the liver with cholesterol supersaturation in bile; disturbed motility with defective absorption and secretion by the gallbladder; increased crystallisation of cholesterol in the gallbladder bile; and slow intestinal transit with increased amount of deoxycholic acid in the bile acid pool. We aimed to evaluate the biliary lipid composition in a large series of gallstone patients, with emphasis on the amount of deoxycholic acid and with respect to number of stones, compared to gallstone free subjects.

Materials and methods Bile was sampled during operations through puncture of the gallbladder from 145 cholesterol gallstone patients, 23 patients with pigment stones and 87 gallstone free patients undergoing cholecystectomy. Biliary lipid composition, cholesterol saturation, bile acid composition, nucleation time and cholesterol crystals were analysed.

The patients with cholesterol gallstones showed higher molar percentage of cholesterol, lower total biliary lipid concentration, higher cholesterol saturation, shorter nucleation time and higher proportion of crystals in bile than the other groups. The nucleation time was significantly shorter in multiple cholesterol gallstone patients, but this was not due to higher cholesterol saturation. Male cholesterol gallstone patients showed higher cholesterol levels, lower total biliary lipid concentration, and higher cholesterol saturation in bile than female patients. There was no difference in biliary content of deoxycholic acid, but significantly lower content of cholic acid in gallstone patients compared to gallstone free patients.

We conclude that deoxycholic acid does not contribute to gallstone formation in cholesterol gallstone patients. The short nucleation time in patients with multiple cholesterol stones is not due to higher cholesterol saturation.
Insulin‐mediated increases in renal plasma flow are impaired in insulin‐resistant normal subjects
Authors: Ter Maaten J. C. , Bakker S. J. L. , Serné E. H. , Moshage H. J. , Donker A. J. M. , Gans R. O. B.
Published: March 2003

Impaired vasodilatation in skeletal muscle is a possible mechanism linking insulin resistance to blood pressure regulation. Increased renal vascular resistance has been demonstrated in the offspring of essential hypertensives. We assessed whether insulin‐mediated renal vasodilatation is impaired in insulin‐resistant normal subjects.

In two groups of 10 insulin‐resistant and 10 insulin‐sensitive normal subjects, we compared the effects of sequential physiological and supraphysiological insulin dosages (50 and 150 mU kg−1 h−1) on renal plasma flow (RPF) and leg blood flow using the euglycaemic clamp technique, 131I‐labelled Hippuran clearances and venous occlusion plethysmography. Time‐control experiments were performed in the same subjects.

Whole‐body glucose uptake amounted to 4·9 ± 2·1 and 11·0 ± 2·4 mg kg −1min−1 in the insulin‐resistant and to 12·7 ± 2·3 and 17·4 ± 2·6 mg kg −1min−1 in the insulin‐sensitive subjects during physiological and supraphysiological hyperinsulinaemia, respectively. RPF increased more in insulin‐sensitive compared to insulin‐resistant subjects during physiological hyperinsulinaemia (13·7 vs. 6·8%, P < 0·05). RPF increased to comparable levels during supraphysiological hyperinsulinaemia. Insulin‐mediated changes in leg blood flow did not differ between groups. In the combined group, we found a positive correlation between insulin‐mediated glucose uptake and changes in RPF during physiological hyperinsulinaemia (r = 0·57, P = 0·009), whereas insulin‐mediated glucose uptake correlated with changes in leg blood flow during supraphysiological hyperinsulinaemia (r = 0·54. P = 0·017).

Our results suggest that the sensitivities of the skeletal muscle and renal vascular bed differ for insulin's vasodilatory action. Insulin‐mediated increases in RPF are impaired in insulin‐resistant but otherwise normal subjects during physiological hyperinsulinaemia.
The role of the insulin‐like growth factor system in adrenocortical tumourigenesis
Authors: Weber M. M. , Fottner C. , Wolf E.
Published: March 2003

Background

The insulin‐like growth factor (IGF) system plays a central role in the mechanism of transformation and tumourigenesis. Elevated levels of IGF‐II and IGF‐I have been found in adrenocortical carcinomas.

Material and methods

We examined binding characteristics and concentrations of both IGF‐receptors in normal adult human adrenocortical glands, and compared them with the IGF‐I receptor binding in adrenocortical tumours of various origins. The human IGF‐I receptor was overexpressed in the mouse adrenocortical tumour cell line Y1, and growth studied in response to IGF stimulation. The influence of IGF‐II on adrenal morphology and function was assessed in transgenic mice that postnatally overexpress IGF‐II.

Results

While the abundance of the IGF‐I receptor in adrenocortical hyperplasias and adenomas was similar to normal tissue, a strong overexpression of the intact IGF‐I receptor was found in three out of four adrenocortical carcinomas. Y1 cells overexpressing the human IGF‐I receptor respond to IGF‐I with an increase in thymidine incorporation by 140%. Furthermore, the antiproliferative effect of ACTH is blunted. In transgenic mice postnatally overexpressing IGF‐II, adrenal weight is increased, mainly due to a 50% increase in the number of zona fasciculata cells. Plasma corticosterone levels in these mice are twofold higher than in controls, in contrast to similar plasma ACTH levels, thus indicating a direct effect of IGF‐II on adrenal cell hyperplasia and function.

Conclusion

There is substantial evidence that the IGF‐system is involved in adrenal growth and tumourigenesis. High local levels of IGF‐II in combination with elevated IGF‐I receptor concentrations would represent a significant growth advantage of the adrenocortical carcinoma cell and could contribute to a highly malignant phenotype. IGF‐II overexpression alone seems not to be sufficient for malignant transformation.
Immunopathogenesis of cholestatic autoimmune liver diseases
Authors: Medina J. , Jones E. A. , García‐Monzón C. , Moreno‐Otero R.
Published: March 2003

Primary biliary cirrhosis and primary sclerosing cholangitis are well recognized chronic cholestatic liver diseases that are considered to have an autoimmune basis. Recent progress in the study of autoimmune liver diseases has improved the recognition and characterization of these conditions. An important component of this progress has been the identification of liver disease‐associated autoantibodies and their respective target antigens, and the development of specific assays for these autoantibodies. In addition, some nonhumoral immunological findings imply an involvement of specific immunopathogenic mechanisms in the development of these conditions. Furthermore, immunogenetic factors associated with increased susceptibility to some of these diseases have been identified. This article reviews the most relevant information relating to the postulated autoimmune pathogenesis of these diseases, with special emphasis on their associated humoral and cellular immunological abnormalities and immunopathogenetic factors. Some of the remaining important unresolved issues relating to the pathogenesis of these diseases, that need to be addressed in further research, are highlighted.
Cardiovascular effects of beta 3‐adrenoceptor stimulation in perinephritic hypertension
Authors: Donckier J. E. , Massart P.‐E. , Van Mechelen H. , Heyndrickx G. R. , Gauthier C. , Balligand J.‐L.
Published: March 2003

Background A new beta 3‐adrenoceptor (β3‐AR) has been shown to mediate peripheral vasodilation. This study was conducted to evaluate effects of the β3‐AR agonist, SR58611 in normal and hypertensive dogs.

Materials and Methods In protocol 1, SR58611 was infused in normal dogs after placebo, after β1/β2 blockade with nadolol, after β1/β2/β3 blockade with bupranolol and after combined autonomic blockade (CAB). In protocol 2, perinephritic hypertension was produced in dogs, which received SR58611 at 3 and 6 weeks of hypertension. Effects of SR58611 were evaluated at 7 weeks of hypertension after CAB.

Results In normal dogs, SR58611 produced a dose‐dependent decrease in mean aortic pressure (AOP) (from 116 ± 19 to 100 ± 19 mmHg, − 14%; P < 0·05) that was accompanied by baroreflex activation (heart rate increased by 70%; P < 0·01). This hypotensive effect resulting from peripheral vasodilation persisted after nadolol or CAB while baroreflex activation was blunted or abolished. A biphasic response of cardiac output, characterized by a rise and a decline (P < 0·05) reflected a reduction in after‐ and pre‐load. After CAB, SR58611 did not modify cardiac contractility. SR58611 stimulated lipolysis as reflected by a 4‐fold increase in blood free fatty acids (FFA) (P < 0·0005). Under CAB, the rise of FFA was reduced (P < 0·01). In hypertensive dogs, SR58611 produced a dose‐dependent decrease in mean AOP (from 168 ± 32 to 125 ± 35 mmHg; − 26%, P < 0·0001), that was greater than in normal dogs (P < 0·05). Reflex‐mediated tachycardia also occurred but at higher blood pressure values. Blood FFA rose similarly (P < 0·0001). Under CAB, heart rate remained unchanged but SR58611 still induced a decrease (P < 0·0001) in mean AOP concomitantly with a rise of (dP/dt)/DP40 (P < 0·005), an effect not observed in normal dogs.

Conclusions β3‐AR stimulation exerts hypotensive effects, increases cardiac contractility and stimulates lipolysis in hypertensive dogs.
Zinc salts precipitate unconjugated bilirubin in vitro and inhibit enterohepatic cycling of bilirubin in hamsters
Authors: Méndez‐Sánchez N. , Roldán‐Valadez E. , Flores M. A. , Cárdenas‐Vázquez R. , Uribe M.
Published: March 2003

Background We have evidence for enterohepatic cycling of bilirubin experimentally and in vivo in humans. This study was designed to investigate whether Zn salts might inhibit such cycling of bilirubin.

Materials and methods Micellar bile salt solutions with unconjugated bilirubin were prepared, appropriate concentrations of Zn salts were added, and unconjugated bilirubin precipitation was measured. Hamsters and Wistar rats were fed a chow diet or a chow diet enriched with 1% ZnSO4, and bilirubin secretion rates were monitored.

Results Unconjugated bilirubin was precipitated maximally (90%) after a 10‐min incubation with 5 mM Zn salts in the pH range of 6·8–9·0. In control hamsters, total bilirubin secretion rates into bile were 36·0 ± 2·8 nmol h−1 100g −1 body weight, whereas they were 25·0 ± 3·3 nmol h−1 100 −1g in the ZnSO4 group (P < 0·05).

Conclusions Zn salts that flocculate at physiological pH adsorb unconjugated bilirubin almost completely from unsaturated micellar BS solutions. In addition, Zn salts administered orally suppress biliary bilirubin secretion rates in hamsters. These findings suggest that the administration of Zn salts may inhibit the enterohepatic cycling of unconjugated bilirubin in humans who are predisposed to pigment gallstone formation due to diet, disease or drugs.
Incidence and geographical distribution of sudden infant death syndrome in relation to content of nitrate in drinking water and groundwater levels
Authors: George M. , Wiklund L. , Aastrup M. , Pousette J. , Thunholm B. , Saldeen T. , Wernroth L. , Zarén B. , Holmberg L.
Published: March 2003

Background Previous studies indicate that the enteral bacterial urease is inhibited in victims of sudden infant death syndrome (SIDS). One possible inhibitor of this bacterial activity is nitrate. If ambient pollution by nitrate is involved in the etiology of SIDS only a fraction of the nitrate concentration not infrequently found in drinking water would be enough for this inhibition.

Methods Occurrence of SIDS (n = 636) in Sweden during the period 1990 through 1996 were analysed regarding geographical and seasonal distribution in relation to the nitrate concentration in drinking water and changes in the groundwater level.

Results Both the birth rate and the incidence of SIDS decreased during the study period. One quarter of the municipalities constituting 11% of the population had no cases, the maximum incidence being 6·5 per 1000 live births. Seasonality: The northernmost parts of the country had its highest incidence when the rest of the country had its lowest incidence, and the occurrence of individual deaths was associated with the recharge of groundwater which increases its nitrate content. The local incidence of SIDS was correlated (rs = 0·34–0·87) to maximally recorded concentrations of nitrate in drinking water.

Conclusions The seasonal distribution of SIDS was widely different from the south to the north of the country and seems to be associated with differences in the groundwater level changes subsequent to precipitation, frost penetration, and melting of snow. Use of drinking water with high peak concentrations or great variations in nitrate concentration was correlated to the incidence of SIDS.
Glutathione in blood of patients with Friedreich's ataxia
Authors: Piemonte F. , Pastore A. , Tozzi G. , Tagliacozzi D. , Santorelli F. M. , Carrozzo R. , Casali C. , Damiano M. , Federici G. , Bertini E.
Published: March 2003

Oxidative stress and mitochondrial dysfunction have long been considered to play a role in Friedreich's ataxia, a neurodegenerative disease due to a GAA expansion in a gene coding for a mitochondrial protein (frataxin), implicated in the regulation of iron metabolism. Since glutathione is an important antioxidant whose role has been recently proposed in the pathogenesis of some neurodegenerative diseases, we investigated glutathione metabolism in the blood of 14 patients with Friedreich's ataxia by measuring total, free and protein‐bound glutathione concentrations.

Blood samples were obtained from 14 unrelated patients with Friedreich's ataxia (nine males, five females) and 20 age‐matched healthy controls (10 males, 10 females). Total and free glutathione concentrations were determined by reverse‐phase liquid chromatography with fluorescence detection; the glutathionyl‐haemoglobin separation from healthy and pathological subjects was obtained by electrospray ionization–mass spectrometry.

We consistently found a reduction of free glutathione levels (0·55 ± 0·06 nmol mg−1 haemoglobin, vs. 8·4 ± 1·79 nmol mg−1 haemoglobin, P < 0·001) in the blood of patients with Friedreich's ataxia, a total glutathione concentration comparable to the controls (15 ± 2·6 nmol mg−1 haemoglobin, vs. 15·4 ± 1·4 nmol mg−1 haemoglobin), and a significant increase of glutathione bound to haemoglobin (15 ± 1·5 vs. 8 ± 1·8%, P < 0·05) in erythrocytes.

Our findings give evidence of an impairment in vivo of glutathione homeostasis in Friedreich's ataxia, suggesting a relevant role of free radical cytotoxicity in the pathophysiology of the disease; this study may also prove useful in the search for an oxidative stress marker in neurodegeneration.
Secretases as targets for drug design in Alzheimer’s disease
Authors: Hendriksen J. V. R. B. , Nottet H. S. L. M. , Smits H. A.
Published: March 2003

Abstract Alzheimer’s disease accounts for the majority of dementia in the elderly. Worldwide, approximately 20 million people are suffering from this devastating disease, with no effective treatment currently available. For efficient drug design, it is important to identify the molecular mechanisms underlying the pathology of the disease. An invariant feature in the pathology of Alzheimer’s disease is the amyloid‐β peptide. Amyloid‐β is produced by endoproteolytic cleavage of the amyloid precursor protein by β‐ and γ‐secretase. In the past 2 years, the protein responsible for β‐secretase activity has been isolated and researchers are close to identifying γ‐secretase. These recent achievements in Alzheimer’s disease research have provided helpful tools for the development of therapeutics.
Alcohol consumption alters insulin secretion and cardiac autonomic activity
Authors: Flanagan D. E. H. , Pratt E. , Murphy J. , Vaile J. C. , Petley G. W. , Godsland I. F. , Kerr D.
Published: March 2003

Background Alcohol may have a cardioprotective effect. One possible mechanism is by modifying insulin resistance/secretion. The aims of this study were: (i) to examine the effect of short‐term alcohol consumption on the metabolic control of glucose tolerance; (ii) to study the influence of short‐term alcohol consumption on cardiac autonomic activity using spectral analysis of heart rate variability.

Methods Twenty‐one healthy subjects, in a randomized crossover design, either received three units of ethanol daily for 1 week or abstained from ethanol. The control of glucose tolerance was assessed using the intravenous glucose tolerance test with minimal modelling.

Results There was no difference in fasting glucose, fasting insulin or insulin sensitivity between the two groups. Alcohol showed a lower insulin first phase insulin response (no alcohol 659·0 ± 394·1 SD, alcohol 535·2 ± 309·1) pmol L−1 min−1, P = 0·027). There was no difference in heart rate or blood pressure but a significant difference in the ratio of high to low frequency spectral power of heart rate variability; (no alcohol 4·55 ± 3·78, alcohol 8·16 ± 6·77, P = 0·033). This suggests decreased sympathetic and/or increased vagal modulation of heart rate in the alcohol group.

Conclusion The finding of no difference in insulin sensitivity between the two groups contrasts with, but does not entirely contradict, the results of previous epidemiological studies – perhaps suggesting that longer term changes such as liver enzyme induction may be important. The difference in insulin secretion questions the validity of previous studies of the influence of alcohol on insulin sensitivity, where insulin levels were used as a surrogate for insulin resistance.
Can a determination of tartrate‐resistant acid phosphatase predict postmenopausal loss of bone mass?
Authors: Rico H. , Arribas I. , Villa L. F. , Casanova F. J. , Hernández E. R. , Cortés‐Prieto J.
Published: March 2003

Background  A study was carried out over a 24‐month interval to determine if an initial measurement of serum tartrate‐resistant acid phosphatase would be predictive of bone mass loss quantified by dual‐energy X‐ray absorptiometry, as total bone mineral content and total bone mineral content corrected for weight.

Design  Sixty‐two women were studied (at onset: mean age 59·7 ± 8·9 years, 10·8 ± 8·8 years since menopause; at conclusion: mean age 61·9 ± 8·8 and 13·0 ± 8·7 since menopause).

Results  A paired Wilcoxon test showed a small, but significant, increase in weight (P < 0·05) and decrease in height (P < 0·05). Total bone mineral content and total bone mineral content corrected for weight decreased (P < 0·005 and 0·0001, respectively). Serum tartrate‐resistant acid phosphatase increased (P < 0·005). Single‐regression analysis showed that the per cent bone mass loss observed between the first and second body bone mineral content measurements correlated negatively with the first serum tartrate‐resistant acid phosphatase determination (r = −0·62, P < 0·0001). Changes in tartrate‐resistant acid phosphatase correlated negatively with changes in total bone mineral content (r = −0·79, P < 0·0001). In a multiple regression analysis of per cent change in bone mass against initially important variables such as age, years since menopause, weight, and tartrate‐resistant acid phosphatase, only tartrate‐resistant acid phosphatase was significant (P < 0·0001). The sensitivity and specifity of tartrate‐resistant acid phosphatase for evaluating bone loss were 86% and 78%, respectively, and the area under the curve was of 0·83 (95% CI 0·71–0·95).

Conclusion  These results show that a simple measurement of serum tartrate‐resistant acid phosphatase can help to predict the potential rate of bone mass loss in women.
Hyperhomocysteinemia and impaired vasomotor function in type 2 diabetes mellitus
Authors: Tan K. C. B. , Karmin O. , Chow W.‐S. , Ai V. H. G. , Siow Y. L. , Lam K. S. L.
Published: March 2003

Background Hyperhomocysteinemia has been shown to adversely affect vascular function. The aim of this study was to determine whether hyperhomocysteinemia was independently associated with changes in endothelium‐dependent and ‐independent vasomotor functions in patients with type 2 diabetes mellitus.

Materials and methods Fasting homocysteine (tHcy) was measured in 123 patients with type 2 diabetes and in 61 nondiabetic controls. Endothelium‐dependent and ‐independent vasodilation was measured using high‐resolution vascular ultrasound.

Results Plasma tHcy concentration was increased in the diabetic patients (11·1 ± 3·7 µmol L−1 vs. 9·8 ± 2·9, P < 0·05). The prevalence of hyperhomocysteinemia (defined as tHcy > 15 µmol L−1) was higher in the diabetic patients (P < 0·05). Within group comparisons showed that both the abnormalities in endothelium‐dependent and ‐independent vasodilation were significantly more severe in diabetic patients with tHcy 10–15 (P < 0·05) and tHcy > 15 µmol L−1 (P < 0·05) than in those patients with tHcy < 10 µmol L−1. When compared with nondiabetic controls matched for tHcy levels, impairment of endothelium‐dependent and ‐independent vasodilation were already evident, even in patients with normal tHcy levels (P < 0·01). Despite significant univariate relationships between tHcy and endothelium‐dependent (r = −0·24, P < 0·01) and ‐independent vasodilation (r = −0·33, P < 0·01) in patients with diabetes, only the relationship between tHcy and endothelium‐independent vasodilation remained significant after adjusting for other cardiovascular risk factors in multiple regression analysis.

Conclusions Impairment of endothelium‐dependent and ‐independent vasodilation was already present in diabetic patients with normal tHcy levels, and these abnormalities became more severe with increasing tHcy levels. Only the association between tHcy and endothelium‐independent vasodilation was free of other cardiovascular risk factors.
Biological effects of secretory phospholipase A2 group IIA on lipoproteins and in atherogenesis
Authors: Jaross Werner , Eckey Rolf , Menschikowski Mario
Published: March 2003

Secretory phospholipase A2 group IIA(sPLA2 IIA) can be produced and secreted by various cell types either constitutionally or as an acute‐phase reactant upon stimulation by proinflammatory cytokines. The enzyme prefers phosphatidylethanolamine and phosphatidylserine as substrates. One important biological function may be the hydrolytic destruction of bacterial membranes. It has been demonstrated, however, that sPLA2 can also hydrolyse the phospholipid monolayers of high density lipoprotein (HDL) and low density lipoprotein (LDL) in vitro. Secretory phospholipase A2‐modified LDL show increased affinity to glycosaminoglycans and proteoglycans, a tendency to aggregate, and an enhanced ability to deliver cholesterol to cells. Incubation of cultured macrophages with PLA2‐treated LDL and HDL is associated with increased intracellular lipid accumulation, resulting in the formation of foam cells. Elevated sPLA2(IIA) activity in blood serum leads to an increased clearance of serum cholesterol. Secretory phospholipase A2(IIA) can also be detected in the intima, adventitia and media of the atherosclerotic wall not only in developed lesions but also in very early stages of atherosclerosis. The presence of DNA of Chlamydia pneumoniae, herpes simplex virus, and cytomegalovirus was found to be associated with sPLA2(IIA) expression and other signs of local inflammation. Thus, sPLA2(IIA) appears to be one important link between the lipid and the inflammation hypothesis of atherosclerosis.
Gastric emptying in myotonic dystrophy
Authors: Rönnblom A. , Andersson S. , Hellström P. M. , Danielsson Å.
Published: March 2003

BackgroundGastrointestinal symptoms are common and important for the quality of life in patients with myotonic dystrophy (MD). Gastric emptying was studied in patients with MD who suffered from symptoms suggesting slow gastric emptying and the effect of prokinetic treatment was evaluated.

MethodsGastric emptying was studied in 10 patients with MD who were suffering from nausea, early satiety, bloating, regurgitation, vomiting, or abdominal pain using a99Tc‐labelled test meal, and was compared with gastric emptying in a group of healthy controls. The patients were subsequently treated with erythromycin and their gastrointestinal symptoms were recorded and the gastric emptying test was repeated.

ResultsPatients with MD had a significantly longer gastric lag phase (46·1 ± 4·3 vs. 31·9 ± 4·0 min,P = 0·03), a slower emptying phase (7·1 ± 0·9 vs. 10·2 ± 0·9 kJ min−1,P = 0·02) and a longer half‐emptying time,T50(141·7 ± 10·5 vs. 98·6 ± 8·7 min,P = 0·01) than a matched control group. Erythromycin did not stimulate the gastric emptying rate. The effect on gastrointestinal symptoms was modest, except for a reduction of diarrhoea.

ConclusionsPatients with MD suffering from nausea, vomiting and early satiety, displayed a slow gastric emptying. Treatment with erythromycin had only moderate effect on gastric emptying or gastric symptoms, but reduced diarrhoea in a majority of the patients.