bluuebunny/crossref_metadata_2025 huggingface dataset:
Polymorphisms of the tumour necrosis factor‐α gene, coronary heart disease and obesity
Authors: Herrmann  , Ricard  , Nicaud  , Mallet  , Arveiler  , Evans  , Ruidavets  , Luc  , Bara  , Parra  , Poirier  , Cambien
Published: March 2003

Background

Tumour necrosis factor‐α (TNF‐α) is a cytokine that has multiple functions. Through its effects on lipid metabolism, coagulation, insulin resistance and endothelial function, TNF‐α could be involved in cardiovascular pathophysiology. Given this possibility, we hypothesized that polymorphisms of the TNF‐α gene might be associated with a predisposition to coronary heart disease (CHD).

Methods

The entire coding region and 1053 bp upstream of the transcription start site of the TNF‐α gene were screened for polymorphisms using polymerase chain reaction–single‐strand conformation polymorphism (PCR‐SSCP) and sequencing. Five polymorphisms were identified: four were located in the upstream region at positions −857, −851, −308, −238 from the first transcribed nucleotide and one was found in a non‐translated region at position +691. Six‐hundred and forty‐one patients with myocardial infarction (MI) and 710 control subjects from the ECTIM Study were genotyped.

Results

The genotype frequencies were similar in cases and control subjects in the high‐risk population of Belfast and in France; however, the TNF‐α/−308A allele was more frequent in Belfast than in France (0.242 vs. 0.157; P < 0.0001), and carriers of this allele were more frequently obese than non‐carriers [1.52 (1.15–1.99), P < 0.004]. No associations were found for the other polymorphisms.

Conclusions

These results suggest that polymorphisms of the TNF‐α gene are unlikely to contribute to CHD risk in an important way, but the TNF‐α/−308 polymorphism should be investigated further in relation to obesity.
Different efficacy of soluble CD14 treatment in high‐ and low‐dose LPS models
Authors: Stelter  , Witt  , Fürll  , Jack  , Hartung  , Schütt
Published: March 2003

Background

About 50% of septic shock cases are attributed to Gram‐negative bacteria or their cell wall compound lipopolysaccharide (LPS, endotoxin). An attractive therapeutic strategy could target the binding of LPS to its cellular receptors. In vitro the soluble form of the endotoxin receptor CD14 (sCD14) competitively prevents binding of LPS to membrane‐bound CD14 and inhibits LPS‐stimulated macrophage responses.

Methods

We tested the in vivo endotoxin‐neutralizing capacity of human recombinant sCD14 using a mouse model of shock induced by 8 μg g−1 of LPS from Salmonella abortus equi.

Results

In this model, treatment with sCD14 reduced mortality if administered before or simultaneously with LPS. However, application of sCD14 had no effect on the secretion of early proinflammatory cytokines and did not protect the animals against the development of apparent shock symptoms and liver injury. sCD14 also failed to prevent LPS‐inducible (7.5 ng g−1) liver injury in galactosamine‐sensitized mice.

Conclusion

In line with these findings, sCD14 did not block LPS‐induced activation of Kupffer cells in vitro, which might explain why the compound only partially protected in vivo.
Gastrin/cholecystokinin type B receptors in the kidney: molecular, pharmacological, functional characterization, and localization
Authors: De Weerth  , Jonas  , Schade  , Schöneberg  , Wolf  , Pace  , Kirchhoff  , Schulz  , Heinig  , Greten  , Von Schrenck
Published: March 2003

Background

Gastrin/cholecystokinin type B receptors (CCKBRs) can be found on parietal cells and smooth muscle cells and are the predominant brain CCK receptors. Recent cloning studies indicate that this receptor type might also be expressed in the kidney.

Materials and methods

We used Northern blot analysis in guinea pig. kidney and reverse transcriptase polymerase chain reaction (RT‐PCR) in several murine kidney cell lines to evaluate this organ for the expression of the CCKBRs. The receptor was pharmacologically characterized by displacement experiments using [125I]‐BH‐CCKs and various agonists and antagonists. Polyclonal antibodies vs. the CCKBRs were raised in chicken, and immunohistochemistry on tissue sections was used to localize the receptor within the organ. The effect of gastrin on renal cell growth was measured using proximal tubulus (MCT) cells, which were cultured with gastrin (10−9 M) for 24–72 h. Cell counts and [3H]‐thymidine incorporation experiments were performed.

Results

CCKBR transcripts can be detected in kidney RNA (tubules > glomeruli > interstitium). RT‐PCR revealed CCKBR transcripts in proximal tubules (MCT cells) and in mesangium (MMC). The medullary thick ascending limb of Henle's loop and several control tissues such as liver and muscle were negative. Displacement experiments using [125I]‐BH‐CCK and various agonists and antagonists identified binding sites with typical CCKBR pharmacology. CCKBRs were localized in the proximal tubulus, distal collecting ducts and mesangium cells. Treatment of rested MCT cells with gastrin 17‐1 induced cell proliferation and [3H]‐thymidine incorporation by at least 40% compared with normal growth (P < 0.05).

Conclusion

These results show for the first time that CCKBRs are present in selected areas of the kidney, and strongly confirm our previous observation that this organ expresses binding sites for [125I]‐gastrin. Furthermore, gastrin might act as a growth factor in the kidney.
Effects of omega‐3 fatty acids and/or antioxidants on endothelial cell markers
Authors: Seljeflot  , Arnesen  , Brude  , Nenseter  , Drevon  , Hjermann
Published: March 2003

Background

Increased expression of cell adhesion molecules and increased procoagulant activity of the vascular endothelium have been postulated to characterize dysfunctional endothelium. The cellular effects of n‐3 fatty acids (n‐3 FAs) and antioxidants are still not clarified.

Methods

In a randomized, factorial two‐by‐two design study, we have investigated 41 male smokers with hyperlipidaemia before and after 6 weeks of supplementation with either n‐3 FAs (4.8 g daily) or placebo with the addition of antioxidants (150 mg of vitamin C, 75 mg of vitamin E and 15 mg of β‐carotene daily) or placebo with regard to the effects on some endothelial cell markers: thrombomodulin (sTM), von Willebrand factor (vWF), tissue plasminogen activator antigen (tPAag) and soluble forms of the cell adhesion molecules E‐selectin, P‐selectin and vascular cell adhesion molecule 1 (VCAM‐1).

Results

In the n‐3 FA group, significant reductions in the plasma levels of vWF (P = 0.034) and sTM (P < 0.001) were demonstrated compared with placebo, whereas increased levels were found for E‐selectin (P = 0.001) and VCAM‐1 (P = 0.010). In the antioxidant group, no differences in changes were noted for any of the variables.

Conclusion

The reduction in the levels of sTM and vWF with n‐3 FA supplementation could indicate an improvement with regard to the haemostatic markers of endothelial dysfunction, whereas the simultaneous increase in the soluble forms of E‐selectin and VCAM‐1 may suggest an adverse effect on the inflammatory system. The antioxidants seem to be neutral in their effect on these endothelial cell markers in our study population of smokers. The interpretation of the soluble forms of these molecules are, however, still debatable.
Hyperglycaemia reduces gastrin‐stimulated gastric acid secretion in humans
Authors: Lam  , Masclee  , De Boer  , Lamers
Published: March 2003

Background

Recent studies have pointed to the role of plasma glucose in the regulation of gastrointestinal function.

Methods

We have investigated the effect of acute hyperglycaemia on gastric acid secretion and pancreatic polypeptide (PP) release. Gastric acid output was measured under basal conditions and in response to intravenous infusion of gastrin‐17 in two doses: 5 pmol kg−1 h for 60 min and 15 pmol kg−1 h for another 60 min. Seven healthy subjects were studied during normoglycaemia and during acute hyperglycaemia at 15 mmol L−1. Acid output was measured by continuous aspiration using phenol red as recovery marker. Plasma PP levels were determined at regular intervals.

Results

Gastrin infusion at 5 pmol kg−1 h significantly (P < 0.05) increased acid output both during normoglycaemia and during hyperglycaemia. Gastrin infusion at 15 pmol kg−1 h further and significantly (P < 0.05) increased the acid output during both experiments. Hyperglycaemia significantly (P < 0.05) reduced basal acid output (2.5 ± 0.9 vs. 6.3 ± 1.9 mmol h−1), low‐dose gastrin stimulated acid output (6.5 ± 1.7 vs. 13.0 ± 1.8 mmol h−1) and high‐dose gastrin stimulated acid output (11.7 ± 3.0 vs. 19.4 ± 3.0 mmol h−1) compared with normoglycaemia. Plasma PP levels were not stimulated by gastrin‐17 infusion and were significantly (P < 0.05) reduced during hyperglycaemia.

Conclusions

(a) Basal and gastrin‐17‐stimulated gastric acid secretion are reduced during hyperglycaemia; (b) infusion of gastrin‐17 to physiological post‐prandial levels does not affect plasma PP levels; (c) plasma PP levels are reduced during hyperglycaemia, suggesting vagal‐cholinergic inhibition of gastric acid secretion during hyperglycaemia.
Type I and type III procollagen propeptides in amniotic fluid of normal pregnancies and in a case of mild osteogenesis imperfecta
Authors: Kauppila  , Tekay  , Risteli  , Koivisto  , Risteli
Published: March 2003

Background

The propeptides derived from type I and III procollagens, PICP, PINP and PIIINP, indicate the synthesis of the corresponding collagens. Their circulating concentrations reflect the growth velocity in infants and children

Methods

We measured these propeptides in 145 samples of amniotic fluid of normal pregnancy. In addition, we have analysed an amniotic fluid and serum sample from a mother with osteogenesis imperfecta, and later the infant's serum sample was also collected for procollagen propeptide analysis.

Results

High concentrations of propeptides, 100–1000 times higher than those in adult serum, were found in early second trimester, decreasing significantly towards term, reflecting the decreased foetal growth rate. Interestingly, the amino‐terminal propeptide of type I procollagen, PINP, decreased more that the corresponding carboxy‐terminal propeptide, PICP, although both are in principle derived from the same protein. At both stages of pregnancy, the discrepant ratio of PICP to PINP indicated a molar excess of PINP. Abnormally low concentrations of PICP and PINP with normal PIIINP concentrations measured in amniotic fluid and in the serum indicated decreased synthesis of type I procollagen in a foetus/infant with mild osteogenesis imperfecta.

Conclusions

Our data show a decrease in collagen synthesis with the stage of pregnancy and lower values of type I procollagen propeptides in a case of OI.
Decreased nitric oxide‐mediated natural killer cell activation in chronic fatigue syndrome
Authors: Ogawa  , Nishiura  , Yoshimura  , Horikawa  , Yoshida  , Okajima  , Matsumura  , Ishikawa  , Nakao  , Tomiyama  , Kanayama  , Kanakura  , Matsuzawa
Published: March 2003

Background

L‐Arginine (
L‐Arg), one of the essential amino acids, has been reported to have an immunomodulatory effect. The precise mechanism of the
L‐Arg‐induced natural killer (NK) cell activation remains unresolved ,and the effect of
L‐Arg on NK cells in chronic fatigue syndrome (CFS) patients has not been estimated.

Methods

NK cell function was evaluated in 20 subjects with CFS and compared with that in 21 healthy individuals.

Results

In healthy control subjects, NK activity was significantly increased after treatment with L‐Arg, an NK function enhancer, for 24 h, whereas the same treatment failed to enhance NK activity in the CFS patients. We thus focused on
L‐Arg metabolism, which involves nitric oxide (NO) production through NO synthase (NOS). The expression of inducible NO synthase (iNOS) transcripts in peripheral blood mononuclear cells was not significantly different between healthy control subjects and CFS patients. The
L‐Arg‐mediated NK cell activation was abolished by addition of NG‐monomethyl‐
L‐arginine, an inhibitor for iNOS. Furthermore, incubation with S‐nitroso‐N‐acetyl‐penicillamine, an NO donor, stimulated NK activity in healthy control subjects but not in CFS patients.

Conclusion

These results demonstrate that the L‐Arg‐induced activation of NK activity is mediated by NO and that a possible dysfunction exists in the NO‐mediated NK cell activation in CFS patients.
In vitro expression of soluble and cell surface‐associated CD44 on endometrial cells from women with and without endometriosis
Authors: Prifti  , Sillem  , Arslic  , Monga  , Rehberger  , Runnebaum
Published: March 2003

Background

Endometriosis is one of the most common benign gynaecological diseases, and attachment of retrogradely shed viable endometrial cells is considered to be important in its development. CD44 is a multifunctional adhesion molecule that undergoes alternative splicing, giving rise to different isoforms.

Methods

The expression of cell surface‐associated CD44 std, v4, v5, v6 and v10 variants before and after cytokine treatment was investigated in endometrial cultures derived from 10 endometriosis patients and 22 women without the disease using immunocytochemistry. The immunoreactivity of soluble CD44 std, v5 and v6 variants was measured in culture medium using an enzyme immunoassay kit.

Results

We report on the presence of soluble CD44 in endometrial culture supernatants. In particular, circulating CD44 standard form levels were significantly higher than levels of splice variants. We also found that both epithelial and stromal cells express surface‐associated CD44 molecules in a distinct pattern and that this expression is not modulated by tumour necrosis factor (TNF)‐α or/and interleukin 1 (IL‐1) α/β. Finally, cell surface‐associated as well as soluble CD44 expression was similar in the two groups.

Conclusion

Our results indicate that endometrial cells can serve as a source of circulating CD44, but a direct role in the pathogenesis of endometriosis is rather improbable.
Lack of interleukin 10 regulation of antigen presentation‐associated molecules expressed on colonic epithelial cells
Authors: Bourreille  , Segain  , Raingeard de la Blétière  , Siavoshian  , Vallette  , Galmiche  , Blottière
Published: March 2003

Background

Colonic epithelial cells may behave as antigen‐presenting cells. Interleukin 10 (IL‐10) is known to play a major role in the intestinal immune system; however, it remains to be determined whether human intestinal epithelial cells express IL‐10 receptor, and whether this cytokine modulates their expression of antigen presentation‐associated molecules

Methods

The binding of biotinylated IL‐10 was studied in SW 1116, HT‐29 and T84 human colonic epithelial cell lines and freshly isolated normal colonic epithelial cells. Reverse transcription‐polymerase chain reaction was also performed to detect IL‐10 receptor mRNA. The effect of IL‐10 on antigen presentation associated molecules was assessed by flow cytometry.

Results

Biotinylated IL‐10 bound to SW 1116, HT‐29, T84, and normal colonic epithelial cells. IL‐10 receptor mRNA was detected in SW 1116 and normal epithelial cells. SW 1116 and HT‐29 cells expressed MHC class I and ICAM‐1, but not CD80, and SW 1116 constitutively expressed HLA‐DR. Interferon‐γ up‐regulated HLA‐DR and ICAM‐1 expression on both cells, whereas lipopolysaccharide increased ICAM‐1 expression only on SW 1116. IL‐10 failed to modulate these antigens, even after stimulation by lipopolysaccharide or interferon‐γ. Moreover, these molecules decreased IL‐10 binding in both lines.

Conclusion

The presence of IL‐10 receptor on intestinal epithelial cells suggest that IL‐10 may play a role in mucosal physiology, however its effect on the immune response remains to be determined.
Parathyroid hormone is not a key hormone in the rapid minute‐to‐minute regulation of plasma Ca2+ homeostasis in rats
Authors: Wang  , Lewin  , Olgaard
Published: March 2003

Background

The role of parathyroid hormone (PTH) in the rapid minute‐to‐minute regulation of plasma Ca2+ (p‐Ca2+) was studied in vivo in rats.

Materials and methods

The rapid calcaemic response to exogenous rat PTH1–34 (16 μg) was examined in normal rats, and the long‐term calcaemic response was examined in parathyroidectomized (PTX) rats receiving PTH1–34 for 24 h at 0.2, 0.4 and 0.8 μg h−1. Acute hypocalcaemia was induced by EGTA for 30 min, and then the rapid recovery of p‐Ca2+ was studied for 130 min in normal rats, 24 h after PTX and in PTX rats infused with exogenous rat PTH1–34. The dynamics of the rapid recovery of p‐Ca2+ was studied at two additional doses of EGTA.

Results

No rapid calcaemic response was observed in the first 60 min after administration of PTH and no hypocalcaemia was seen for 2 h after acute PTX. This slow effect of PTH suggests that PTH might not be responsible for maintaining the stable p‐Ca2+ on a rapid minute‐to‐minute basis. EGTA induced acute hypocalcaemia in both normal and PTX rats (P < 0.01). In both groups a rapid and similar increase in p‐Ca2+ took place 10 min after discontinuing EGTA (P < 0.05). Within 60 min, p‐Ca2+ increased further, independently of the presence of PTH. Infusion of PTH to PTX rats did not affect the rapid recovery of p‐Ca2+ (P < 0.05) from EGTA induced hypocalcaemia.

Conclusion

PTH is not a key hormone in the rapid recovery of p‐Ca2+ after induction of hypocalcaemia, but might, however, set the long‐term levels of p‐Ca2+ maintained by mammalian organisms. The involvement of an as yet unknown factor in the rapid regulation of p‐Ca2+ is suggested.
Delayed post‐prandial lipid metabolism in subjects with intra‐abdominal visceral fat accumulation
Authors: Taira  , Hikita  , Kobayashi  , Bujo  , Takahashi  , Murano  , Morisaki  , Saito
Published: March 2003

Background

Individuals with obesity, in particular those with intra‐abdominal visceral fat accumulation, are known to have various complications, such as hyperlipidaemia, impaired glucose tolerance, hyperinsulinaemia and hypertension, leading to the development of coronary heart disease. Post‐prandial hyperlipidaemia has repeatedly been shown to be an independent risk factor for coronary heart disease. The aim of the present study was to investigate post‐prandial lipoprotein metabolism in subjects with excessive visceral fat accumulation.

Materials and methods

Eighty‐three patients (52 men, 31 women) [average age 48 ± 14 years; mean body mass index (BMI) 25 ± 5 kg m−2] were recruited to the study. Visceral (or subcutaneous) fat accumulation was analysed as areas of fat deposition by computerized tomography at the umbilicus level. After a 12‐h overnight fast, oral vitamin A and a fatty meal (40 g m−2 fresh cream containing 50 000 units m−2 vitamin A) were administered to these subjects. The concentration of retinyl palmitate (RP) was measured by high‐performance liquid chromatography.

Results

The visceral fat area (V) was positively correlated with plasma triglyceride (TG) 0, 2, 4 and 6 h after fat loading and with plasma RP 0, 4 and 6 h after fat loading. The BMI did not show any correlation with plasma TG and RP at any point. The visceral fat area was positively correlated with the RP area under the curve (AUC) in the serum from the subjects [V vs. RP AUC: n = 83, r = 0.327, P = 0.013]. The BMI of the subjects did not show any correlation with the RP AUC (r = 0.021, P = 0.85).

Conclusion

These results suggest that post‐prandial lipid metabolism is impaired in subjects with intra‐abdominal visceral fat accumulation, irrespective of BMI, leading to the development and progression of coronary atherosclerosis.
Energetics and function of the failing human heart with dilated or hypertrophic cardiomyopathy
Authors: Kalsi K. K. , Smolenski R. T. , Pritchard R. D. , Khaghani A. , Seymour A‐M. L. , Yacoub M. H.
Published: March 2003

Background

Impaired energy metabolism in the failing human heart could be an important mechanism of functional deterioration. The purpose of this study was to assess the changes of myocardial energy metabolism in the human heart at end‐stage heart failure.

Materials and methods

The left ventricular myocardium of patients undergoing heart transplantation due to dilated (DCM, n = 14) or hypertrophic cardiomyopathy (HCM, n = 5) and non‐diseased donor heart samples (n = 4) were analysed for citrate synthase (CS), enzymes of the glycolytic pathway as well as concentrations of phosphocreatine (PCr), creatine (Cr), adenine and guanine nucleotides.

Results

Total creatine levels (phosphocreatine + creatine) were significantly decreased (P < 0.05) in both groups of diseased hearts (3.87 ± 0.57 in DCM, 5.09 ± 1.23 in HCM compared with control 10.7 ± 3.5 μmol g−1 wet weight). There was a trend for higher guanine nucleotide content in failing hearts, but no significant differences were observed in total adenine nucleotides and total NAD content. CS was markedly reduced (P < 0.05) in both groups of diseased hearts: in the DCM to 13.8 ± 1.3 μmol min−1 g−1 wet weight, and in HCM to 11.9 ± 2.4 compared with the control 29.2 ± 2.2. Glycolytic enzymes were decreased compared with the control, and this decrease was greater in DCM than in HCM. Echocardiographic indices of contractility were considerably better in hypertrophic cardiomyopathy.

Conclusion

Despite the different mechanisms of cardiac failure and the differences in contractility of the heart we have observed, metabolic changes are very similar in hypertrophic and dilated cardiomyopathy. Depletion of the creatine pool suggests an alteration in the intracellular energy reserves and transfer, whereas the decrease in citrate synthase activity suggests reduced oxidative capacity in both dilated and hypertrophic cardiomyopathy.
Elevation of plasma leptin concentrations in obese hyperinsulinaemic hypothyroidism before and after treatment
Authors: Kautzky‐Willer  , Ludwig  , Nowotny  , Roden  , Huemer  , Widhalm  , Vierhapper  , Waldhäusl  , Roden
Published: March 2003

Background

Plasma leptin is considered to play a role in maintenance of energy balance and body weight by neuroendocrine mechanisms. Thyroid hormones are permissive for adrenergic activation, which in turn has been shown to decrease leptin expression. This study was therefore designed to test the hypothesis that hyperthyroidism results in lower leptin concentrations, whereas hypothyroidism leads to higher plasma leptin concentrations. In addition, the effects of normalization of thyroid function on plasma leptin were investigated.

Materials and methods

Fasting plasma leptin concentrations and body fat mass (total body electrical conductivity) were measured in patients with overt hypothyroidism and hyperthyroidism before and after successful treatment. Plasma leptin, glucose, insulin and free fatty acid concentrations were monitored during an oral glucose tolerance test (OGTT 75 g).

Results

Fasting plasma leptin concentrations were similar in lean patients, independently of their thyroid function (hyperthyroid 12.5 ± 2 ng mL−1, hypothyroid 10.2 ± 2 ng mL−1, euthyroid 12.7 ± 3 ng mL−1). In obese hypothyroid patients, plasma leptin was threefold higher (P < 0.0005) than in lean hypothyroid patients, twofold higher (P < 0.005) than in obese hyperthyroid patients matched for fat mass and 30% increased (P < 0.01) compared with obese euthyroid subjects. There were no differences between fasting and post‐prandial (OGTT) leptin concentrations in any group. Normalization of thyroid function did not affect plasma leptin, which remained elevated (P < 0.005) in formerly obese hypothyroid patients. Plasma leptin was not associated with serum thyroid hormones but highly correlated with body mass index and body fat mass in all patients (r = 0.85, P < 0.001). Plasma leptin correlated with plasma insulin concentration only in hyperthyroid patients (P < 0.01, r = 0.64), who presented with blunted stimulation of insulin release and higher plasma glucose (P < 0.05) than hypothyroid subjects.

Conclusion

The results indicate that (a) the correlation of leptin with body fat mass is preserved in thyroid dysfunction, (b) plasma leptin is markedly increased in obese hypothyroid hyperinsulinaemic patients and (c) plasma leptin is not affected by oral glucose loading.
Comparison of bolus versus fractionated oral applications of [13C]‐linoleic acid in humans
Authors: Demmelmair  , Iser  , Rauh‐Pfeiffer  , Koletzko
Published: March 2003

Background

The endogenous conversion of linoleic acid into long‐chain polyunsaturated fatty acids is of potential importance for meeting substrate requirements, particularly in young infants. After application of [13C]‐linoleic acid, we estimated its conversion to dihomo‐γ‐linolenic and arachidonic acids from only two blood samples.

Design

Oral tracer doses were given to five healthy adults as a single bolus. In four subjects the tracer was given in nine equal portions over 3 days. Concentration and 13C content of fatty acids from serum phospholipids were analysed by gas chromatography combustion isotope ratio–mass spectrometry. Areas under the tracer–concentration curves were calculated, and fractional transfer and turnover rates estimated from compartmental models.

Results

The median fractional turnover of linoleic acid was 93.7% per day (interquartile range 25.3) in the bolus group and 80.0% per day (6.3) in the fraction group (NS). Fractional conversion of linoleic to dihomo‐γ‐linolenic acid was 1.5% (0.9) vs. 2.1% (0.7) (bolus vs. fraction, P < 0.05), and fractional conversion of linoleic to arachidonic acid was 0.3% (0.3) vs. 0.6% (0.3) (bolus vs. fraction, NS). In the fraction group conversion was significantly higher based on areas under the curve. The ratio of tracer concentration in conversion products to linoleic acid 48 h after dosing correlated very well (r ≥ 0.94, P < 0.05) with the ratio of areas under the curve.

Conclusions

Using areas under the curve overestimates the conversion, because different residence times are not considered. Estimation of conversion intensity appears possible with only one blood sample obtained after tracer application.
Physiological doses of calcium regulatory hormones do not normalize bone cells in uraemic rats
Authors: Szabó A. , Freesmeyer M. G. , Abendroth K. , Stein G. , Rosivall L. , El‐Shakmak A. , Ritz E.
Published: March 2003

Background

Low bone turnover despite normal parathyroid hormone (PTH) concentrations has been found in many patients with end‐stage renal failure. Hyporesponsiveness to the calcaemic action is also a known feature of uraemia. Hyporesponsiveness of bone surface cells involved in bone modelling has not been demonstrated to date. It was the purpose of this study using a rat model of moderate renal failure to investigate whether doses of PTH and calcitriol that reverse the effect of parathyroidectomy on calcaemia also normalize bone surface cell activity.

Materials and methods

Sham‐operated pair‐fed male Spraque–Dawley rats were compared with subtotally nephrectomized (SNX), parathyroidectomized (PTX) rats that received either solvent or calcitriol (5 pmol kg −1 h−1) + 1,34 rat PTH (100 ng kg −1 h−1) by osmotic mini‐pump. Histomorphometric measurements were carried out in the vertebral body (L5).

Results

In SNX/PTX animals, calcitriol + 1,34 rat PTH caused a modest increase in serum calcium (S‐Ca) within the normal range. Osteoclast surface per cent was significantly lower in solvent‐treated SNX/PTX rats than in sham‐operated controls [3.7 ± 2.8 osteoclast surface/bone surface (OcS/BS%) vs. 6.3 ± 3.9], and this was not normalized by PTH + calcitriol (3.3 ± 3). In contrast, osteoblast surface per cent and osteoid surface per cent were increased over values in sham‐operated rats; as a result, co‐administration of calcitriol and 1,34 rat PTH caused a highly significant increase in fractional bone volume (BV/TV).

Conclusions

The results show that administration of PTH and calcitriol in doses that raise serum calcium fails to normalize the percentage of osteoclast surface, but was effective in raising osteoblast number and osteoblast volume in experimental renal failure. The results argue for abnormal response of bone cells to calcium‐regulating hormones and/or the action of factors other than calcium regulatory hormones in the genesis of skeletal abnormalities of renal failure.
Pneumocystis carinii major surface glycoprotein induces interleukin‐8 and monocyte chemoattractant protein‐1 release from a human alveolar epithelial cell line
Authors: Benfield  , Lundgren  , Shelhamer  , Lundgren
Published: March 2003

Background

The major surface glycoprotein (MSG) is an abundant, immunogenic glycoprotein located on the surface of Pneumocystis carinii. Little is known about the proinflammatory effects of MSG.

Design

We have investigated the effect of human MSG on the secretion of the chemokines interleukin 8 (IL‐8) and monocyte chemoattractant protein‐1 (MCP‐1) from an alveolar epithelial cell line (A549).

Results

Incubation of A549 cells with MSG in concentrations from 0.4 to 10 μg mL−1 for 24 h caused dose‐dependent increases in IL‐8 release (3.4‐fold above control, P < 0.01). Time course experiments showed increases in IL‐8 release at 4 h, 8 h and 24 h compared with control cultures (all P < 0.01). There was a minor (13%) dose‐ and time‐related increase in MCP‐1 release at 24 h (P = 0.02). Co‐incubation of MSG with mannan or β‐glucan decreased IL‐8 release by 48% and 42% respectively, suggesting that MSG stimulates A549 cells in part through carbohydrate moieties. Dexamethasone significantly inhibited MSG‐induced IL‐8 release in concentrations of 10−6–10−8 mol L−1 compared with control experiments (P < 0.01). Ribonuclease protection assays for steady‐state IL‐8 mRNA showed that increases in response to MSG stimulation occurred by 4 h and persisted throughout 8 h of stimulation.

Conclusion

These findings suggest that MSG can alter alveolar epithelial cytokine release and may be capable of modulating the local inflammatory response in this manner.
A novel visual immunoassay for coeliac disease screening
Authors: Garrote  , Sorell  , Alfonso  , Acevedo  , Ortigosa  , Ribes‐Koninckx  , Gavilondo  , Méndez
Published: March 2003

Background

To date, the most commonly accepted techniques for the screening of coeliac disease are indirect immunofluorescence and enzyme‐linked immunosorbent assay (ELISA), which reveal antiendomysium and antigliadin antibodies respectively. We report the use of a simple visual system for coeliac disease screening based on the use of Staphylococcus aureus protein A, which binds to both IgG and IgA, thus avoiding the need for two parallel immunoassays.

Materials and methods

Opaque polystyrene microwell strips coated with a wheat gliadin extract were incubated with sera followed by incubation with protein A–colloidal gold conjugate. The resulting colour was compared with that of positive and negative control sera. The procedure took less than an hour.

Results

One hundred and forty‐five biopsy‐proven sera, 94 from active coeliac patients and 51 from non‐coeliac patients with diverse gastrointestinal pathologies or diabetes mellitus, were assayed. Ninety of the 94 sera from the active coeliac patients were positive, whereas only 3 of the 51 non‐coeliac control subjects were positive. The technique has a sensitivity of 95.7% and a specificity of 94.1%.

Conclusions

The sensitivity and specificity of the visual system are greater than those of most ELISA systems and are similar to those observed with IgA antiendomysium antibodies when tested in the same population. Moreover, it is inexpensive, quick, simple to perform and easy to interpret, i.e. it requires no qualified personnel. It is for these features, together with the outstanding sensitivity and specificity, that we propose this immunoassay as a new test for reliable coeliac disease screening.
Laureate ESCI award for excellence in clinical science 1999 Cytokines and the human immunodeficiency virus: from bench to bedside
Authors: Poli
Published: March 2003

Replication of the human immunodeficiency virus (HIV), the causative agent of the acquired immunodeficiency syndrome (AIDS), is under the control of both viral and host factors. Among the latter, the regulatory network of cytokines has been shown to affect virtually every step of the virus life cycle, from cell entry to budding of new progeny virions. Proinflammatory cytokines, such as tumour necrosis factor α, can either trigger or potentiate HIV expression via activation of the cellular transcription factor NF‐κB. Other molecules, including interleukin 6 (IL‐6) and the interferons, can up‐regulate HIV expression by acting predominantly at post‐transcriptional and/or post‐translational levels. Anti‐inflammatory cytokines, including transforming growth factor β, IL‐4 and IL‐10, counteract these effects but can also potentiate viral replication under different experimental conditions. Chemotactic cytokines (chemokines) have recently entered the arena of host factors controlling viral spreading as potent inhibitors competing with the virus for cell‐surface 7‐transmembrane domain receptors also acting, together with CD4, as entry co‐receptors for HIV. The cytokine network is constitutively activated in most HIV‐infected individuals, as demonstrated by recent analysis of intracellular signalling molecules such as the Janus kinase/signal transducer and activator of transcription pathway. Finally, cytokines have already shown their potential use as pharmacological agents able to restore at least some of the compromised immune functions in infected individuals, as exemplified by the potent enhancing effect of IL‐2 on the number of circulating CD4+ T lymphocytes.
The growth and the control of human immunodeficiency virus in the lung: implications for highly active antiretroviral therapy
Authors: White  , Agostini  , Israel‐Biet  , Semenzato  , Clarke
Published: March 2003

In recent years, it has become apparent that the lung is an important niche for the proliferation of human immunodeficiency virus (HIV), which may have implications for highly active antiretroviral therapy (HAART). The lung itself is a major site for the opportunistic infections associated with the progression to acquired immune deficiency syndrome (AIDS), specifically Pneumocystis carinii, Myobacterium tuberculosis and pyogenic bacteria. These cases of active pulmonary complications are direct indicators of enhanced progression to AIDS‐defining illness and increased morbidity and mortality. It is therefore essential that the interaction between the lung and HIV is fully understood. Recent research indicates the lung may be a major sanctuary for the virus, with distinct evolution and replication in contrast to other target organs for HIV. In this review, we will discuss the recent findings of HIV infection, evolution, host factors involved in the control of HIV within the lung and the impact this may have on current therapy.
Amino acid concentration in the interstitium of human skeletal muscle: a microdialysis study
Authors: Gutierrez  , Anderstam  , Alvestrand
Published: March 2003

Background

The microdialysis technique has been widely used for in vivo monitoring of the interstitial composition of several tissues. Remarkably high concentrations of taurine and glycerol were reported in a recent human study. As taurine and glycerol are predominantly present in the intracellular space, cellular trauma after probe insertion may have resulted in elevated interstitial concentrations. With the present study we wanted to investigate the impact of the initial trauma on the interstitial concentrations of amino acids and glycerol.

Methods

Microdialysis probes were inserted into the vastus lateralis muscle in eight subjects. Using a slow perfusion rate of 0.3 μL min−1, dialysate samples were collected in five 75‐min periods. Simultaneously, plasma samples were taken from a peripheral vein for amino acid determination.

Results

During the first collection period, the dialysate concentration for 21 measured amino acids was on average 180% ± 51% higher than the concentration in plasma water. This difference decreased to 52% ± 15%, 32% ± 8%, 37% ± 8% and 31% ± 7% during periods 2, 3, 4 and 5 respectively. Carnosine, which is not present in plasma, was detected in high concentrations in the interstitium during the first collection period and decreased subsequently.

Conclusion

In the post‐absorptive phase, the concentrations of most amino acids in muscle interstitium are slightly higher than in venous plasma water. The leakage of intracellular amino acids, because of probe insertion, will initially lead to an overestimation of the actual interstitial concentration of amino acids. Therefore, reliable baseline values of amino acids cannot be obtained until 120–150 min after probe insertion. The dialysate concentration of carnosine may be used as a marker of cellular leakage.
Hydroxyurea interferes with antigen‐dependent T‐cell activation in vitro
Authors: Orendi  , Nottet  , De Vos  , Visser  , Snippe  , Boucher  , Verhoef
Published: March 2003

Background

Hydroxyurea is believed to inhibit human immunodeficiency virus type 1 (HIV‐1) in HIV disease by decreasing the amount of intracellular deoxynucleotides needed for viral replication. A plasma concentration of 400 μmol L−1 is tolerated in oncological diseases. The present study focused on the possible interference of hydroxyurea with antigen‐dependent T‐cell activation as an alternative explanation for inhibiting HIV replication in vivo.

Methods

The effect of hydroxyurea on common antigen‐induced cell proliferation was studied in peripheral blood mononuclear cells (PBMC) in vitro.

Results

Hydroxyurea inhibited Candida albicans‐induced cell proliferation at a low concentration (1 μmol L−1), while at least 10 μmol L−1 was required to block HIV‐1 replication in phytohaemagglutinin (PHA)‐stimulated PBMC.

Conclusion

Hydroxyurea inhibits antigen‐induced lymphoproliferation in vitro at a concentration at which it does not inhibit PHA‐induced HIV replication. Hydroxyurea may inhibit HIV‐1 in CD4+ T cells in vivo not only by decreasing the amount of intracellular deoxynucleotides, but more specifically by interfering with antigen‐dependent T‐cell activation, thereby causing a reduction in the number of HIV target cells.
Distal procto‐colitis and n‐3 polyunsaturated fatty acids: the mechanism(s) of natural cytotoxicity inhibition
Authors: Almallah  , El‐Tahir  , Heys  , Richardson  , Eremin
Published: March 2003

Background

Altered natural killer (NK) and lymphokine‐activated killer (LAK) cell activities have been reported with ulcerative colitis (UC). Previously, we have shown that in patients with UC, the n‐3 polyunsaturated fatty acids (PUFAs), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), specifically inhibit natural cytotoxicity with clinical improvement in disease activity. The aim of this study therefore was to evaluate the possible mechanism(s) involved in this inhibition, and in particular the alteration of production of interleukin 2 (IL2) and the arachidonic acid metabolite leukotriene B4 (LTB4), both known to modulate NK cell activity.

Materials and methods

Each patient with procto‐colitis received either fish oil extract (EPA 3.2 g, DHA 2.4 g; n = 9) or placebo (n = 9) daily for 6 months. Monthly assessment included disease activity using clinical and sigmoidoscopic scores. Peripheral blood mononuclear (PBMN) cells were isolated and NK cell cytotoxic activity in vitro was measured. Monthly serum samples were analysed for LTB4, IL2 and soluble IL2 receptors (sIL2R).

Results

The n‐3 PUFAs group had significantly reduced NK cell activity, compared with the placebo group (P < 0.05, Mann–Whitney U‐test). In the n‐3 PUFA group, incubation of PBMN cells for 72 h with recombinant interleukin 2 (rIL2) reversed the NK inhibition. In patients with active proctocolitis, serum levels of LTB4 correlated positively with NK cell cytotoxicity (r = 0.873, P < 0.05, Kendall's correlation coefficient). After six months of n‐3 PUFAs supplementation, serum levels of LTB4 were undetectable with concurrent significant reduction in NK cell cytotoxic activity. The latter was associated with significant reduction of serum IL2 and sIL2R levels (P < 0.05).

Conclusion

This study has demonstrated both evidence of suppression of immune reactivity and concurrent reduction in disease activity in patients with proctocolitis receiving n‐3 PUFAs supplementation. This may have important implications for therapy in patients with UC.
Insulin resistance, lipid and fatty acid concentrations in 867 healthy Europeans
Authors: Baldeweg  , Golay  , Natali  , Balkau  , Del Prato  , Coppack
Published: March 2003

Background

Insulin resistance, dyslipidaemia and abnormal nonesterified fatty acid (NEFA) metabolism are features of the ‘metabolic syndrome’, but the mechanisms of these relationships are uncertain.

Materials and methods

We studied associations between insulin resistance and lipoprotein concentrations by retrospective analysis of euglycaemic hyperinsulinaemic clamp data from 867 normoglycaemic subjects in 21 European centres. Data on NEFA concentrations were available in a subgroup of 541 subjects from 9 clinical centres. These subjects' characteristics do not vary significantly from those of the whole cohort.

Results

After adjustment for the effects of age, sex, obesity and intercentre variability, regression analysis showed relationships between triglycerides and markers of insulin sensitivity. There were significant correlations between triglycerides and fasting plasma glucose (P < 0.0001), fasting plasma insulin (P < 0.0001) and mean glucose infusion rate at steady state (M‐value, P < 0.0001). Indices of insulin resistance were related to NEFA concentrations. Fasting NEFA were negatively correlated with the M‐value (P < 0.0001). Non‐esterified fatty acids at steady state were positively correlated with fasting markers of insulin resistance: fasting plasma glucose (P < 0.05), fasting plasma insulin (P < 0.005) and negatively correlated with the M‐value (P < 0.0005). There were relationships between fasting concentrations of plasma lipids and of NEFAs. Non‐esterified fatty acids at steady state correlated with fasting triglycerides (P < 0.0001), but not with any of the other plasma lipoprotein concentrations. The associations of fasting triglycerides with the M‐value and with NEFAs at steady state were independent of each other. All these associations were independent of obesity and geographical location

Conclusion

The results in this large cohort of healthy European subjects suggest that triglyceride concentrations depend upon both insulin's gluco‐regulation (estimated by glucose uptake) and antilipolytic insulin action (measured by NEFA levels) during an euglycaemic clamp.
Effects of percutaneous transluminal coronary angioplasty on coronary adenosine concentrations in humans
Authors: Paganelli  , Saadjian  , Sampol  , Maixent  , Levy  , Guieu
Published: March 2003

Background

Even minimal amounts of adenosine is released during myocardial ischemia. Its role in coronary blood flow has been extensively studied, but little is known about its behaviour during percutaneous transluminal angioplasty (PTCA) in man.

Material and methods

Using in situ samples the aim of this study was to evaluate adenosine plasma concentration before and after PTCA. Ten patients (8 men and 2 women, mean age 65 ± 9 years) with a single stenosis of the left anterior descending coronary artery (LAD) of at least 70% and 10 healthy volunteers (4 men and 6 women, mean age 55 ± 9 years) were included in the study.

Results and discussion

We found that there is a close relationship between the degree of the stenosis and the adenosine concentrations in the great cardiac vein and in the LAD, and that after PTCA there is a drop in adenosine concentration downstream from the stenosis. This study confirms the crucial role of adenosine in coronary blood flow control.
Plasma membrane polarity of polymorphonuclear leucocytes from children with primary ciliary dyskinesia
Authors: Fiorini  , Littarru  , Coppa  , Kantar
Published: March 2003

Background

Polymorphonuclear leucocytes (PMN) from subjects with primary ciliary dyskinesia (PCD) can have abnormal locomotory systems. The locomotory activity of PMN is the result of biochemical events mediated by the plasma membrane. In this study we investigated plasma membrane polarity of PMN from children with PCD.

Design

Membrane polarity was studied in 11 children with PCD and in healthy controls by measuring the steady‐state fluorescence excitation and emission spectra of 2‐dimethylamino[6‐lauroyl]naphthalene (Laurdan), which is known to be incorporated at the hydrophobic–hydrophilic interface of the bilayer, displaying spectral sensitivity to the polarity of its surroundings. Laurdan shows a marked steady‐state emission red shift in polar solvents, with respect to nonpolar solvents. Moreover, the effect of the microtubule disassembling agent colchicine on PMN membrane polarity was evaluated.

Result

Our results show a red shift of the fluorescence excitation and emission spectra of Laurdan in PMN from the PCD group with respect to the control group. These data indicate an increase in membrane polarity of PMN from the PCD group. Treatment of PMN with colchicine induced a red shift in the Laurdan excitation and emission spectra with the same trend observed in PMN from the PCD group.

Conclusion

PMN from children with PCD are characterized by an increased plasma membrane polarity. These changes could be the basis of the modifications in the locomotory activities of PMN. The observed alterations may be attributed to abnormalities in the cytoskeleton.
Molecular mechanisms of dissociative glucocorticoid activity
Authors: Bamberger C. M. , Schulte H. M.
Published: March 2003

Background

Glucocorticoids mediate their effects on target cells via transactivation and transrepression of certain target genes. While conventional glucocorticoids do not distinguish between transactivation and transrepression, new glucocoticoids should be able to dissociate these effects, thus lowering the potential of unwanted side‐effects of glucocorticoids in clinical use. In this study, we developed a new experimental system to test potentially selective glucocorticoids in normal lymphocytes.

Materials and methods

Following pretreatment with phytohaemagglutinin, normal lymphocytes were transfected, using electroporation, with pGL3 luciferase reporter vectors under the control: (1) of the human IL‐2 promoter; and (2) of a glucocorticoid response element (GRE). Luciferase activity was measured in response to various steroid compounds, including the potentially dissociative glucocorticoid medroxyprogesterone acetate (MPA).

Results

The IL‐2 promoter was induced 267.2 ± 27.5‐fold (mean ± SD) by phorbol ester and ionomycin. In these cells, hydrocortisone and dexamethasone caused a 22.9 ± 3.6% and a 38.4 ± 10% reduction in luciferase activity, respectively. Under GRE control, hydrocortisone stimulated luciferase activity 6.4 ± 0.50‐fold and dexamethasone 8.2 ± 0.4‐fold. MPA‐induced transrepression was 73.3 ± 7.2% for the IL‐2 promoter, and transactivation was 2.4 ± 0.4‐fold with the GRE‐driven construct. The natural progestin progesterone did not have significant effects on either construct.

Conclusions

This is the first system that allows efficient analysis of glucocorticoid‐dependent transactivation and transrepression in normal human lymphocytes. Compared to conventional glucocorticoids, MPA can be reffered to as a dissociative glucocorticoid, its transrepression/transactivation ratio being 6.6 (transrepression 1.91/transactivation 0.29), with dexamethasone being the standard (transrepression 1/transactivation 1). We conclude that MPA is a highly promising substance for the treatment of autoimmune/inflammatory diseases.