Interaction of the small interstitial proteoglycans biglycan, decorin and fibromodulin with transforming growth factor beta

We have analysed the interactions of three proteoglycans of the decorin family, decorin, biglycan and fibromodulin, with transforming growth factor beta (TGF-beta). The proteoglycan core proteins, expressed from human cDNAs as fusion proteins with Escherichia coli maltose-binding protein, each bound TGF-beta 1. They showed only negligible binding to several other growth factors. Intact decorin, biglycan and fibromodulin isolated from bovine tissues competed with the fusion proteins for the TGF-beta binding. Affinity measurements suggest a two-site binding model with Kd values ranging from 1 to 20 nM for a high-affinity binding site and 50 to 200 nM for the lower-affinity binding site. The stoichiometry indicated that the high-affinity binding site was present in one of ten proteoglycan core molecules and that each molecule contained a low-affinity binding site. Tissue-derived biglycan and decorin were less effective competitors for TGF-beta binding than fibromodulin or the non-glycosylated fusion proteins; removal of the chondroitin/dermatan sulphate chains of decorin and biglycan (fibromodulin is a keratan sulphate proteoglycan) increased the activities of decorin and biglycan, suggesting that the glycosaminoglycan chains may hinder the interaction of the core proteins with TGF-beta. The fusion proteins competed for the binding of radiolabelled TGF-beta to Mv 1 Lu cells and endothelial cells. Affinity labelling showed that the binding of TGF-beta to betaglycan and the type-I receptors in Mv 1 Lu cells and to endoglin in endothelial cells was reduced, but the binding to the type-II receptors was unaffected. TGF-beta 2 and 3 also bound to all three fusion proteins. Latent recombinant TGF-beta 1 precursor bound slightly to fibromodulin and not at all to decorin and biglycan. The results show that the three decorin-type proteoglycans each bind TGF-beta isoforms and that slight differences exist in their binding properties. They may regulate TGF-beta activities by sequestering TGF-beta into extracellular matrix.

Antibodies against transforming growth factor-beta 1 suppress intimal hyperplasia in a rat model

Intimal hyperplasia is induced by therapeutic vascular interventions and often results in clinically important narrowing of the vascular lumen. Examination of the role of TGF-beta 1 in a rat carotid artery injury model confirmed the presence of a previously reported increase in TGF-beta 1 mRNA in the media of injured arteries. Administration of neutralizing anti- TGF-beta 1 antibodies significantly (P < 0.05) reduced the size of the intimal lesions that developed after carotid balloon injury. A control antibody had no effect. The intimal/medial area ratio was also reduced in the anti-TGF-beta 1 group relative to controls (P < 0.01). Immunohistochemical staining showed that two TGF-beta 1-induced extracellular matrix components, EDA + fibronectin and versican, were greatly increased in the untreated neointimal lesions, but were almost completely absent from the lesions of the anti-TGF-beta 1-treated animals. We conclude that TGF-beta 1 is causally involved in the development of intimal hyperplasia, and that anti-TGF-beta 1 agents may be useful in achieving at least partial control of this condition.

A novel assay for extracellular matrix remodeling associated with liver fibrosis: An enzyme-linked immunosorbent assay (ELISA) for a MMP-9 proteolytically revealed neo-epitope of type III collagen

OBJECTIVES

Accumulation of extracellular matrix (ECM) components and increased matrix-metalloprotease (MMPs) activity are hallmarks of fibrosis. We developed an ELISA for quantification of MMP-9 derived collagen type III (CO3) degradation.

DESIGN AND METHODS

A monoclonal antibody targeting a specific MMP-9 cleaved fragment of CO3 was used for development of a competitive ELISA. The assay was investigated in serum and tissues from bile duct ligated rats (BDL).

RESULTS

The ELISA showed no cross-reaction with either intact CO3, or other collagens. The intra- and inter-assay CV were below 10%. Liver fibrosis was demonstrated in BDL animals by semi quantitative scoring (P<0.0001). Serum levels of CO3-610 increased 2.5 fold in BDL animals (P<0.001). The CO3-610 levels were 5 fold higher in ex vivo cultures of fibrotic livers compared to controls (P<0.001).

CONCLUSION

We have developed a novel ELISA for measuring a specific fragment CO3 generated by MMP-9 important in pathogenesis of liver fibrosis.

The role of glycation cross-links in diabetic vascular stiffening

Previous studies have shown that biomechanical analysis of aorta from diabetic subjects reveals a marked increase in stiffness compared to aorta from age-matched control subjects. In the present paper we have proposed that this increased stiffness can be attributed to glycation-induced inter-molecular cross-links based on a direct analysis of the two known glycation cross-links, the fluorescent pentosidine and the non-fluorescent NFC-1. There was a significant difference in the increase in concentration of both cross-links with increasing age for both the intima (p < 0.0025) and the media (p < 0.0005) from the diabetic compared to the control subjects, but no correlation with the mature enzymic cross-link hy droxylysyl-pyridinoline. Finally, we have obtained a significant correlation of stiffness with both glycation cross-links (NFC-1, r = 0.86; p < 0.005 and pentosidine r = 0.75, p < 0.05), but the concentration of NFC-1 is about 50 times greater than that of pentosidine, indicating that it is the major glycation cross-link responsible for the stiffening of the aorta.

Increased plasma concentrations of osteoprotegerin in type 2 diabetic patients with microvascular complications

OBJECTIVE

Osteoprotegerin (OPG) is a newly identified inhibitor of bone resorption. Recent studies indicate that OPG also acts as an important regulatory molecule in the vasculature. Plasma levels of OPG seem to be elevated in subjects with diabetes as well as in non-diabetic subjects with cardiovascular disease. The aim of the present study was to examine the association between plasma OPG levels and microvascular complications and glycemic control in patients with type 2 diabetes.

DESIGN AND METHODS

Four groups of 20 subjects in each, individually matched for age and gender, were included in the study: (i) subjects with normal glucose tolerance (NGT); (ii) subjects with impaired glucose tolerance (IGT); (iii) type 2 diabetic patients without retinopathy; and (iv) type 2 diabetic patients with diabetic maculopathy (DMa). Plasma concentration of OPG was measured in duplicate by a sandwich ELISA method. Furthermore, fundus photography, flourescein angiography, and measurements of urinary albumin excretion rate (RIA) were performed.

RESULTS

Plasma OPG was significantly higher in diabetic (iii+iv) than in NGT (i) subjects (3.04+/-0.15 vs 2.54+/-0.16 ng/ml, P<0.05). Plasma OPG was significantly higher in the DMa (iv) group than in the NGT (i) group (3.25+/-0.23 vs 2.54+/-0.16 ng/ml, P=0.01). Moreover, plasma OPG was significantly higher (3.61+/-0.36 ng/ml) in the group of diabetic subjects with both microalbuminuria and DMa (n=7) than in the NGT (i) (2.54+/-0.16 ng/ml, P<0.01), IGT (ii) (2.82+/-0.21 ng/ml, P<0.05), and no retinopathy (iii) groups (2.83+/-0.20 ng/ml, P<0.05).

CONCLUSIONS

We found increased levels of OPG in plasma from diabetic patients with microvascular complications. This finding indicates that OPG may be involved in the development of vascular dysfunction in diabetes [corrected].

Arterial osteoprotegerin: increased amounts in diabetes and modifiable synthesis from vascular smooth muscle cells by insulin and TNF-alpha

AIMS/HYPOTHESIS

Extracellular matrix modifications and linear medial calcifications are elements of diabetic macroangiopathy. We hypothesised that the bone-related protein osteoprotegerin (OPG) may occur in altered amounts in the arterial wall in diabetes, putatively associated with altered synthesis from vascular cells.

METHODS

The amount of OPG in the thoracic aorta, obtained at autopsy from 21 diabetic and 42 sex- and age-matched controls, was measured in tissue extracts by an ELISA. The production of OPG was estimated in conditioned media by an ELISA, and OPG mRNA was estimated by RT-PCR in vascular cells grown in vitro.

RESULTS

The content of OPG was increased in tunica media samples from diabetic individuals. No differences between diabetic and non-diabetic subjects were observed in tunica intima. Human vascular smooth muscle cells (HVSMCs) produced approximately 30 times more OPG than human umbilical vein endothelial cells. The OPG production into the medium decreased dose- and time-dependently after insulin treatment (maximal effect approximately 60% of control) in HVSMCs, whereas TNF-alpha supplement gave rise to increased OPG synthesis in a time- and dose-dependent manner (maximal effect approximately 200% of control). Similar effects on OPG mRNA expression were observed. Addition of growth hormone (10 ng/ml) or extra glucose (25 mmol/l) to the growth medium had no effect.

CONCLUSIONS/INTERPRETATION

Increased OPG concentrations in the arterial wall in diabetes may be part of generalised matrix alterations, putatively related to the development of vascular calcifications. Altered arterial OPG content may be a consequence of the effects of hormones and cytokines, like insulin and TNF-alpha.

Increased aortic stiffness in patients with type 1 (insulin-dependent) diabetes mellitus

The biomechanical properties of aortic samples from patients with Type 1 (insulin-dependent) diabetes mellitus and age- and sex-matched control subjects were analysed using a materials testing machine. The specimens were prepared from tissue outside areas of visible atherosclerosis in order to discriminate between primary Type 1 diabetic alterations in the aortae and secondary changes due to increased atherosclerosis. We paid special attention to the correction of biomechanical parameters for differences in wall thickness and registration of specimen length values. In the Type 1 diabetic aortae a marked reduction was found in the extensibility and an increase in their stiffness. The reduced extensibility was correlated significantly to the duration of Type 1 diabetes. The pronounced alterations in the mechanical properties could not be explained by the increase in the wall thickness which was observed among the Type 1 diabetic patients and the alterations could not be correlated to the grade of atherosclerosis in the thoracic aorta. The results of the present study, therefore, strongly suggest that Type 1 diabetic patients develop alterations in the arterial connective tissue independent of the presence of atherosclerosis. Such primary alterations in the vessel wall may play a role in the pathogenesis of large vessel disease among these patients.

Medial arterial calcification in diabetes and its relationship to neuropathy

Calcification of the media of arterial walls is common in diabetes and is particularly associated with distal symmetrical neuropathy. Arterial calcification also complicates chronic kidney disease and is an independent risk factor for cardiovascular and all-cause mortality. The term calcification is not strictly accurate because the morphological changes incorporate those of new bone formation, i.e. ossification. The processes are complex, but are closely related to those involved in bone homeostasis, and it is relevant that calcification of the arterial wall and osteopenia often co-exist. One particular factor linked to the development of arterial calcification is distal symmetrical neuropathy; indeed, it has been suggested that neuropathy explains the distal distribution of arterial calcification in diabetes. It has also been suggested that the link with neuropathy results from loss of neuropeptides, such as calcitonin gene-related peptide, which are inherently protective. The association between distal symmetrical neuropathy and calcification of the arterial wall highlights the fact that neuropathy may be an independent risk factor for cardiovascular mortality.

Glycosaminoglycans in the human aorta in diabetes mellitus: a study of tunica media from areas with and without atherosclerotic plaque

Alterations in the connective tissue of the arterial wall have been suggested to play a role in the development of macrovascular disease in diabetes mellitus. The present study deals with changes in the content of GAG in aortic tunica media in human diabetes by separately analysing normal areas and areas with fibrous plaques. The thoracic aorta from 15 diabetic patients (7 with IDDM, 8 with NIDDM), and 30 sex- and age-matched non-diabetic subjects were collected at autopsy. Tunica intima was removed and GAG were isolated from the dried defatted and pulverized tunica media. GAG were quantified by uronic acid analysis and characterized by electrophoresis on cellulose acetate. Results showed that IDDM patients had a relative and absolute increase in hyaluronic acid in normal tunica media compared to non-diabetic subjects. There was a significant positive correlation between hyaluronic acid content of normal tunica media and duration of diabetes, but not between hyaluronic acid content and age. When tunica media from plaque areas was compared to normal areas the same pattern was evident in diabetic patients as in non-diabetic patients--significantly increased proportion of dermatan sulphate and reduced hyaluronic acid. The data agree with the notion that the arterial wall is subject to different pathological processes in diabetes, one of classical atherosclerosis with changes in GAG similar to non-diabetic subjects, and the other seen in areas without plaques with dissimilar alterations in GAG. These data therefore support the concept of the presence of a macrovascular disease in diabetes different from atherosclerosis.

Plasma osteoprotegerin levels predict cardiovascular and all-cause mortality and deterioration of kidney function in type 1 diabetic patients with nephropathy

AIMS/HYPOTHESIS

The bone-related peptide osteoprotegerin is produced by vascular cells and is involved in the process of vascular calcification. The aim of this study was to investigate the predictive value of plasma levels of osteoprotegerin in relation to mortality, cardiovascular events and deterioration in kidney function in patients with type 1 diabetes.

METHODS

This prospective observational follow-up study included 397 type 1 diabetic patients with overt diabetic nephropathy (243 men; age [mean+/-SD] 42.1 +/- 10.6 years, duration of diabetes 28.3 +/- 9.9 years, GFR 67 +/- 28 ml min(-1) 1.73 m(2)) and a group of 176 patients with longstanding type 1 diabetes and persistent normoalbuminuria (105 men; age 42.6 +/- 9.7 years, duration of diabetes 27.6 +/- 8.3 years).

RESULTS

The median (range) follow-up period was 11.3 (0.0-12.9) years. Among patients with diabetic nephropathy, individuals with high osteoprotegerin levels (fourth quartile) had significantly higher all-cause mortality than patients with low levels (first quartile) (covariate-adjusted hazard ratio [HR] 3.00 [1.24-7.27]). High osteoprotegerin levels also predicted cardiovascular mortality (covariate-adjusted HR 4.88 [1.57-15.14]). Furthermore, patients with high osteoprotegerin levels had significantly higher risk of progression to end-stage renal disease than patients with low levels (covariate-adjusted HR 4.32 [1.45-12.87]). In addition, patients with high levels of plasma osteoprotegerin had an elevated rate of decline in GFR.

CONCLUSIONS/INTERPRETATION

High levels of osteoprotegerin predict all-cause and cardiovascular mortality in patients with diabetic nephropathy. Furthermore, high levels of osteoprotegerin predict deterioration of kidney function towards end-stage renal disease.

Diverse effects of inhibition of 3-hydroxy-3-methylglutaryl-CoA reductase on the expression of VCAM-1 and E-selectin in endothelial cells

The expression of monocyte adhesion molecules, such as VCAM-1 (vascular cell adhesion molecule-1) and E-selectin, on the surface of the endothelium is an important step in the initiation and progression of atherosclerotic lesions. We hypothesized that the inhibition of 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase in endothelial cells could influence the expression of VCAM-1 and E-selectin. Using cultured human umbilical vein endothelial cells, we found that mevastatin (0.1-1 microM) significantly reduced the expression of VCAM-1 protein in cells activated by tumour necrosis factor-alpha (TNF-alpha) for 7 h. In contrast, TNF-alpha-induced E-selectin protein expression was augmented after mevastatin treatment. Mevastatin inhibited the mRNA expression of both VCAM-1 and E-selectin in TNF-alpha-stimulated endothelial cells. The activity of the transcription factor nuclear factor-kappa B, which is known to regulate the transcription of VCAM-1 and E-selectin, was significantly reduced after incubation with mevastatin. Analysis of the time-dependent variation in the TNF-alpha-induced expression of E-selectin, and estimation of the rate of surface disappearance of E-selectin together with measurement of the amounts of E-selectin molecules secreted, indicated that mevastatin inhibited the surface removal of E-selectin. This is compatible with the observed increase in E-selectin expression after statin treatment. All observed effects of mevastatin were reversed by mevalonate, the product of the HMG-CoA reductase reaction. In conclusion, inhibition of HMG-CoA reductase in endothelial cells attenuates VCAM-1 expression, but increases E-selectin expression, after cytokine induction. These diverse effects are associated with changes in the transcriptional regulation of the two adhesion molecule genes and modulation of the surface removal of E-selectin.

A role for collagen type IV in cardiovascular disease?

Over the past decade, studies have repeatedly found single-nucleotide polymorphisms located in the collagen ( COL) 4A1 and COL4A2 genes to be associated with cardiovascular disease (CVD), and the 13q34 locus harboring these genes is one of ~160 genome-wide significant risk loci for coronary artery disease. COL4A1 and COL4A2 encode the α₁- and α₂-chains of collagen type IV, a major component of basement membranes in various tissues including arteries. Despite the growing body of evidence indicating a role for collagen type IV in CVD, remarkably few studies have aimed to directly investigate such a role. The purpose of this review is to summarize the clinical reports linking 13q34 to coronary artery disease, atherosclerosis, and artery stiffening and to assemble the scattered pieces of evidence from experimental studies based on vascular cells and tissue collectively supporting a role for collagen type IV in atherosclerosis and other macrovascular disease conditions.

Diabetic macroangiopathy and atherosclerosis

In the present study, we have compared and analyzed published data related to the pathogenesis of the large vessel disease in diabetes. The prevailing opinion appears to be that diabetes accelerates the mechanism that leads to the development of classical atherosclerosis. However, as an alternative, we have amassed data that point to the presence of a diabetic macroangiopathy. This phenomenon comprises a constellation of nonatherosclerotic large vessel abnormalities. Today, we know that accumulation of periodic acid-Schiff (PAS)-positive material, as laminin, fibronectin, and type IV collagen, occurs together with hyaluronic acid and various types of connective tissue and calcium deposition. All these changes occur independent of the presence of atherosclerosis in the large vessels of diabetic patients. It seems to us that these observations emphasize that the concept of a specific diabetic macroangiopathy is a more fruitful working hypothesis than the usual theory of a link between atherosclerosis and diabetes. It provides a causal relationship (although the mechanism is unknown) between such changes and the abnormal metabolism in diabetes and a background for research strategy and tactics, aiming finally at the possibility of prevention and/or treatment of this common and dangerous disease.

Influence of insertion/deletion polymorphism in the ACE-I gene on the progression of diabetic glomerulopathy in type 1 diabetic patients with microalbuminuria

OBJECTIVE

To investigate the influence of the insertion/deletion polymorphism of the ACE gene on the progression of early diabetic glomerulopathy in patients with and without antihypertensive treatment (AHT).

RESEARCH DESIGN AND METHODS

There were 30 microalbuminuric patients with >5 years of type 1 diabetes who had renal biopsies taken at baseline and after 26-48 months of follow-up. Of the 30 patients, 13 (4 with II genotype and 9 with ID and DD genotypes) were randomized to AHT (enalapril or metoprolol) during the study. The ACE genotype was determined by a polymerase chain reaction. Glomerular structural changes were measured by stereological methods.

RESULTS

Of the patients, 8 had the II genotype, 19 had ID genotype, and 3 had DD genotype. During the study, basement membrane thickness, matrix star volume, and the overall diabetic glomerulopathy index were increased in patients with ID and DD genotypes only (P < 0.001, P = 0.01, P < 0.001, respectively). Among those with ID and DD genotypes, progression of basement membrane thickening and diabetic glomerulopathy index were increased in those without AHT, as compared with the antihypertensive treated patients (P < 0.001, P = 0.02, respectively). In multivariate analysis, the ACE genotype had an independent influence on the progression of basement membrane thickening (P = 0.01), when AHT (P < 0.001) and the mean HbAlc during the study (P < 0.001) were also taken into account. ACE genotype tended to be independently associated with the diabetic glomerulopathy index (P = 0.05).

CONCLUSIONS

Microalbuminuric type 1 diabetic patients carrying the D-allele have an increased progression of diabetic glomerulopathy. Presence of this allele and no AHT seems to enhance this process. Larger studies are needed to confirm the clinical significance of our findings.

Biomechanical wall properties and collagen content in the partially obstructed opossum esophagus

A specially designed probe was used to investigate biomechanical wall properties of the esophagus in opossums with distal esophageal banding. A balloon was stepwise inflated and deflated 6 cm above the lower esophageal sphincter before the banding and at 2 weeks postoperatively. After animals were killed, collagen content of the esophageal wall was determined. Preoperatively, cross-sectional area and wall tension at maximal inflation of the balloon, compliance, and hysteresis were 108.04 +/- 7.23 mm2, 5.8 +/- 0.3 cm H2O/m, 0.664 +/- 0.081 mm2/cm H2O, and 101.14 +/- 18.89 mm2, respectively. Postoperatively, the parameters increased to 357.45 +/- 54.22 mm2 (P < 0.001), 10.5 +/- 1.4 cm H2O/m (P < 0.001), 2.402 +/- 0.420 mm2/cm H2O (P < 0.001), and 225.86 +/- 44.56 mm2 (P < 0.05), respectively. The collagen content was 0.065 +/- 0.004 and 0.104 +/- 0.009 mg/mg dry defatted weight in the mid and distal normal esophagus, respectively, compared with 0.110 +/- 0.012 and 0.121 +/- 0.012 mg/mg in the banded group (P < 0.05 in the middle part). A positive correlation was shown between the maximal cross-sectional area and the collagen content in the mid-esophagus (P < 0.05). In conclusion, biomechanical wall properties were altered significantly, indicating dilatation and decreased ability of the esophageal wall to resist intraluminal pressure.

Expression of somatostatin receptors on human pituitary adenomas in vivo and ex vivo

The distribution and biologic activity of somatostatin receptor subtypes (SSTR) in pituitary adenomas is not clarified, especially regarding clinically non-functioning adenomas (NFPA). We therefore characterized SSTR in human pituitary adenomas by combining molecular biology and in vivo scintigraphy. Co-expression of gonadotropin-releasing hormone receptor (GnRH-R) mRNA was also assessed to see whether this feature was associated with adenoma subtype and SSTR status. Pituitary tumor biopsies were obtained during transsphenoidal adenomectomy from 21 patients (11 NFPA, 7 acromegalics, 2 prolactinomas, 1 Cushing's disease). Expression of mRNA encoding the 5 known SSTR subtypes and the GnRH-R was determined by RT-PCR. Twelve patients also underwent a pre-operative somatostatin receptor scintigraphy. Most adenomas (no.=18) expressed mRNA for more than one SSTR. SSTR2 mRNA was expressed in 18 cases, whereas SSTR4 was absent in all but one. SSTR3 was frequently expressed in NFPAs. Somatostatin receptor scintigraphy was positive in most cases, and with a significantly higher uptake index in GH-producing adenomas all of which expressed SSTR2 mRNA. The uptake index appeared to be related to receptor density rather than tumor volume. Expression of GnRH-R mRNA was found in both NFPAs and GH-producing adenomas and was not significantly associated with a particular SSTR subtype population.

IN CONCLUSION

1) the distribution of SSTR is not significantly different between NFPA and GH-producing adenomas; and 2) somatostatin receptor scintigraphy reveals a higher uptake in GH-producing adenomas which is not significantly related to either SSTR distribution or tumor volume.

Aortic collagen alterations in human diabetes mellitus. Changes in basement membrane collagen content and in the susceptibility of total collagen to cyanogen bromide solubilisation

Structural alterations in arterial extracellular matrix components have been suggested to play a role in the development of arterial disease among patients with diabetes mellitus. This study examines the quantity and quality of collagenous components in aortas from diabetic patients. In order to obtain data about the arterial tissue concentration of type IV and V collagen in diabetic and non-diabetic patients, aortas from 21 patients with diabetes (9 with Type 1 (insulin-dependent) diabetes and 12 with Type 2 (non-insulin-dependent) diabetes), were collected at autopsy together with aortas from groups of sex- and age-matched patients. Intima and media samples from normal and fibrous plaque areas from the individual vessels were evaluated. Pulverized, dried and defatted tissue samples were subjected to chemical solubilization with cyanogen bromide and subsequent immuno-chemical quantitation of the dissolved type IV and V collagen in an ELISA. It was found that the concentration of type IV collagen was increased in the tunica media both in plaque and non-plaque areas in the samples from the diabetic patient groups as compared to the non-diabetic groups. No consistent differences in type IV collagen concentrations were found between diabetic and non-diabetic patients in tunica intima. The type V collagen concentrations and the total collagen content were not altered in the diabetic samples. The fraction of the total collagen that was solubilized during cyanogen bromide treatment was determined, and it was found that this fraction was decreased in most tissue areas in the diabetic patient groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Laser-assisted microdissection of membrane-mounted paraffin sections for polymerase chain reaction analysis: identification of cell populations using immunohistochemistry and in situ hybridization

Laser microbeam microdissection (LMM) is an increasingly important method for obtaining pure cell samples for genetic and proteomic analysis. Immunohistochemistry (IHC) and in situ hybridization (ISH) are useful techniques for targeting specific cell populations for microdissection but are difficult to apply with the tissue support membranes often used during LMM. Using detection of cytokeratins and Epstein-Barr virus gene products in head and neck carcinoma as a model, we describe optimized protocols for membrane and section preparation and for low temperature antigen retrieval that allow IHC and ISH to be used reliably on membrane mounted paraffin tissue sections. Visualization of cellular targets was markedly improved by staining and this could be further improved using a variety of optical media before microdissection. Tissue fragments thus stained were suitable for subsequent polymerase chain reaction analysis of extracted DNA using standard techniques. These IHC and ISH procedures are generally applicable and will be useful for detecting a wide range of antigens and nucleic acids in paraffin sections in conjunction with LMM.

Production of hyaluronan and chondroitin sulphate proteoglycans from human arterial smooth muscle--the effect of glucose, insulin, IGF-I or growth hormone

BACKGROUND

Although it is recognized that the extracellular matrix is important for cell proliferation, migration and metabolism of growth factors, the regulation of the synthesis of hyaluronan and chondroitin sulphate proteoglycan (CSPG) in the vessel wall is poorly understood.

OBJECTIVE

To examine the role of glucose, insulin, IGF-I and human growth hormone (hGH) on the accumulation of hyaluronan and CSPG using cultures of human aortic smooth muscle cells.

METHODS

The cultures were exposed for 36 h. The CSPG content in the incubation medium was measured by a combination of digestion with testicular hyaluronidase and precipitation of [35SO4(2-)]-labelled material with ethanol and trichloroacetic acid. Hyaluronan was estimated using a radiometric assay.

RESULTS

Glucose and insulin reduced the amount of synthesized hyaluronan (2P<0.01). Stimulation of synthesis was seen with hGH (2P<0.01), whereas no effect was observed with IGF-I. The production of CSPG was increased with glucose and hGH (2P<0.01), but showed no change with insulin.

CONCLUSIONS

The present data obtained with human arterial smooth muscle cells in vitro showed that glucose, insulin and hGH can influence the accumulation of hyaluronan and CSPG. These observations may be relevant for an understanding of diabetic macroangiopathy.

Baseline findings of the population-based, randomized, multifaceted Danish cardiovascular screening trial (DANCAVAS) of men aged 65–74 years

Background

The challenge of managing age-related diseases is increasing; routine checks by the general practitioner do not reduce cardiovascular mortality. The aim here was to reduce cardiovascular mortality by advanced population-based cardiovascular screening. The present article reports the organization of the study, the acceptability of the screening offer, and the relevance of multifaceted screening for prevention and management of cardiovascular disease.

Methods

Danish men aged 65–74 years were invited randomly (1 : 2) to a cardiovascular screening examination using low-dose non-contrast CT, ankle and brachial BP measurements, and blood tests.

Results

In all, 16 768 of 47 322 men aged 65–74 years were invited and 10 471 attended (uptake 62·4 per cent). Of these, 3481 (33·2 per cent) had a coronary artery calcium score above 400 units. Thoracic aortic aneurysm was diagnosed in the ascending aorta (diameter 45 mm or greater) in 468 men (4·5 per cent), in the arch (at least 40 mm) in 48 (0·5 per cent) and in the descending aorta (35 mm or more) in 233 (2·2 per cent). Abdominal aortic aneurysm (at least 30 mm) and iliac aneurysm (20 mm or greater) were diagnosed in 533 (5·1 per cent) and 239 (2·3 per cent) men respectively. Peripheral artery disease was diagnosed in 1147 men (11·0 per cent), potentially uncontrolled hypertension (at least 160/100 mmHg) in 835 (8·0 per cent), previously unknown atrial fibrillation confirmed by ECG in 50 (0·5 per cent), previously unknown diabetes mellitus in 180 (1·7 per cent) and isolated severe hyperlipidaemia in 48 men (0·5 per cent).

In all, 4387 men (41·9 per cent), excluding those with potentially uncontrolled hypertension, were referred for additional cardiovascular prevention. Of these, 3712 (35·5 per cent of all screened men, but 84·6 per cent of those referred) consented and were started on medication.

Conclusion

Multifaceted cardiovascular screening is feasible and may optimize cardiovascular disease prevention in men aged 65–74 years. Uptake is lower than in aortic aneurysm screening.

Under control of the Ren-1c promoter, locally produced transforming growth factor-beta1 induces accumulation of glomerular extracellular matrix in transgenic mice

Our purpose was to elucidate the hypothesis that paracrine-produced transforming growth factor (TGF)-beta1 regulates the accumulation of extracellular matrix (ECM) in renal glomeruli, a hallmark of diabetic nephropathy. To produce TGF-beta1 from the juxtaglomerular apparatus in mouse kidneys, we cloned a mouse Ren-1c promoter fragment (-4.100 to +6 base pairs) upstream of porcine TGF-beta1 (pTGF-beta1) cDNA, mutated to ensure secretion of biologically active TGF-beta beta1. The resulting transgenic mice had significantly more TGF-beta1 in their kidneys than was in those of nontransgenic controls, as confirmed by immunohistochemistry, and the production of TGF-beta1 was enhanced in vivo by captopril-induced stimulation of the Ren-1c promoter. Overproduction of pTGF-beta1 close to the glomerulus resulted in a local accumulation of ECM, composed partly of collagen type IV and laminin, and thickening of the basement membrane, characteristic features of diabetic nephropathy. Interstitial accumulation of ECM and signs of tubular atrophy were present only in older mice (>5 months of age). Results from in situ hybridization and immunohistochemistry suggest that pTGF-beta1 stimulated the production of endogenous TGF-beta1 along collecting ducts and connecting tubules. The increased amount of biologically active TGF-beta1, transgenic as well as endogenous, was corroborated by heightened proteoglycan synthesis from incubated kidney slices. This transgenic model demonstrates that sustained local expression of TGF-beta1 leads to glomerulopathy. We conclude that autocrine- or paracrine-produced TGF-beta1 may play a role in the development of glomerular diseases, such as diabetic nephropathy.

Geographic variation of freeze-tolerance in the earthworm Dendrobaena octaedra

Freeze-tolerance and some of the underlying biochemical defence mechanisms in the earthworm Dendrobaena octaedra was investigated. Survival after slow cooling to -2 degrees C, -4 degrees C, or -6 degrees C was analysed in D. octaedra from three geographic regions representing large differences in winter temperature (Denmark, Finland and Greenland). A large variation in freeze-tolerance between the three populations of D. octaedra was found. Earthworms from the northern populations (Finland and Greenland) tolerated lower temperatures (-6 degrees C) than earthworms from the Danish population (poor survival at -4 degrees C and -2 degrees C). In the Finnish population, freezing led to the production of high concentrations of glucose, which reached values much higher than controls (94 mg g(-1) vs. 2 mg g(-1) dry weight). Other potential cryoprotectants were not elevated after freezing. The Danish and Greenlandic populations had substantially lower mean glucose levels after freezing than the Finnish population (about 15 mg g(-1)). Danish earthworms rapidly frozen did not accumulate glucose, and did not survive freezing at -2 degrees C. Danish earthworms exposed to osmotic stress in Ringer's solutions, containing different concentrations of glycerol, showed significantly elevated glucose levels, but did not survive rapid freezing. It was determined if freezing had an influence on the reproduction of the earthworms. After warming to summer temperatures (15 degrees C), survivors of freezing produced viable cocoons. In a field experiment it was tested if natural acclimatization during autumn and winter months had an effect on freeze-tolerance in the Danish population. There was a significant increase of post-freeze survival during this period. The results of the freezing experiments are discussed in relation to the general ecology of D. octaedra.

The DanCavas Pilot Study of Multifaceted Screening for Subclinical Cardiovascular Disease in Men and Women Aged 65-74 Years

OBJECTIVE/BACKGROUND

This pilot study of a large population based randomised screening trial investigated feasibility, acceptability, and relevance (prevalence of clinical and subclinical cardiovascular disease [CVD] and proportion receiving insufficient prevention) of a multifaceted screening for CVD.

METHODS

In total, 2060 randomly selected Danish men and women aged 65-74 years were offered (i) low dose non-contrast computed tomography to detect coronary artery calcification (CAC) and aortic/iliac aneurysms; (ii) detection of atrial fibrillation (AF); (iii) brachial and ankle blood pressure measurements; and (iv) blood levels of cholesterol and hemoglobin A1c. Web based self booking and data management was used to reduce the administrative burden.

RESULTS

Attendance rates were 64.9% (n = 678) and 63.0% (n = 640) for men and women, respectively. In total, 39.7% received a recommendation for medical preventive actions. Prevalence of aneurysms was 12.4% (95% confidence interval [CI] 9.9-14.9) in men and 1.1% (95% CI 0.3-1.9) in women, respectively (p < .001). A CAC score > 400 was found in 37.8% of men and 11.3% of women (p < .001), along with a significant increase in median CAC score with age (p = .03). Peripheral arterial disease was more prevalent in men (18.8%, 95% CI 15.8-21.8) than in women (11.2%, 95% CI 8.7-13.6). No significant differences between the sexes were found with regard to newly discovered AF (men 1.3%, women 0.5%), potential hypertension (men 9.7%, women 11.5%), hypercholesterolemia (men 0.9%, women 1.1%) or diabetes mellitus (men 2.1%, women 1.3%).

CONCLUSION

Owing to the higher prevalence of severe conditions, such as aneurysms and CAC ≥ 400, screening for CVD seemed more prudent in men than women. The attendance rates were acceptable compared with other screening programs and the logistical structure of the screening program proved successful.

Insulin resistance in vascular endothelial cells promotes intestinal tumour formation

The risk of several cancers, including colorectal cancer, is increased in patients with obesity and type 2 diabetes, conditions characterized by hyperinsulinemia and insulin resistance. Because hyperinsulinemia itself is an independent risk factor for cancer development, we examined tissue-specific insulin action in intestinal tumor formation. In vitro, insulin increased proliferation of primary cultures of intestinal tumor epithelial cells from Apc^Min/+ mice by over 2-fold. Surprisingly, targeted deletion of insulin receptors in intestinal epithelial cells in Apc^Min/+ mice did not change intestinal tumor number or size distribution on either a low or high-fat diet. We therefore asked whether cells in the tumor stroma might explain the association between tumor formation and insulin resistance. To this end, we generated Apc^Min/+ mice with loss of insulin receptors in vascular endothelial cells. Strikingly, these mice had 42% more intestinal tumors than controls, no change in tumor angiogenesis, but increased expression of vascular cell adhesion molecule-1 (VCAM-1) in primary culture of tumor endothelial cells. Insulin decreased VCAM-1 expression and leukocyte adhesion in quiescent tumor endothelial cells with intact insulin receptors and partly prevented increases in VCAM-1 and leukocyte adhesion after treatment with tumor necrosis factor-α. Knockout of insulin receptors in endothelial cells also increased leukocyte adhesion in mesenteric venules and increased the frequency of neutrophils in tumors. We conclude that although insulin is mitogenic for intestinal tumor cells in vitro, its action on tumor cells in vivo is via signals from the tumor microenvironment. Insulin resistance in tumor endothelial cells produces an activated, proinflammatory state that promotes tumorigenesis. Improvement of endothelial dysfunction may reduce colorectal cancer risk in patients with obesity and type 2 diabetes.

A new transcutaneous bilirubinometer, BiliCheck, used in the neonatal intensive care unit and the maternity ward

Transcutaneous bilirubin (TcB) was measured with a new bilirubinometer, BiliCheck, in 261 jaundiced infants in the neonatal intensive care unit (NICU) [gestational age (GA) 25-43 wk] (group 1) and in 227 healthy jaundiced term and near-term infants (GA 35-43 wk) (group 2). Imprecision of a single determination of TcB measured on the forehead [TcB(h)], expressed as 1 standard deviation, was 15-18 micromol l(-1). No statistically significant difference between intraoperator and interoperator imprecision was found. There was a good correlation between TcB(h) and total serum bilirubin (TSB) in both groups of infants, although TcB(h) was on average lower than TSB. In the NICU infants, TcB(h), other things being equal, was lower in males than in females, and decreased with increasing postnatal age, for the same TSB level. In the infants in both groups who had a GA > or = 35 wk, sick infants had a higher TcB(h) than healthy infants for the same TSB level. The differences were statistically significant, but small and of minor clinical significance. Blood haemoglobin concentration, GA and ethnic origin were not found to influence TcB(h), i.e. BiliCheck corrects sufficiently for these factors. In all 488 infants, TcB was measured at four different body sites. Measurements on the forehead and sternum [TcB(s)] correlated well with TSB, while measurements on the knee and foot correlated less well. In the NICU infants TcB(h) predicted TSB statistically significantly better than TcB(s), while in the healthy term and near-term infants TcB(h) and TcB(s) predicted TSB equally well. Therefore, the preferable body site for measurement of TcB under routine conditions is the forehead. By retrospective analysis of the data, a screening model is presented whereby TcB(h) can be used to screen infants who require phototherapy. We found that using screening limits for TcB(h), which are 70% of the currently used phototherapy limits for TSB, 80% of blood samples in healthy term and near-term infants, and 42% of NICU infants with GA > or = 32 wk, could be avoided.

CONCLUSION

BiliCheck is suitable for screening both NICU and healthy newborn infants with jaundice, with regard to the need for phototherapy. The authors recommend using a TcB(h) limit which is 70% of the currently recommended TSB limits for phototherapy, to decide whether TSB needs to be measured.