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The high affinity sulfonylurea receptor 1 (SUR1) is involved in the metabolism of glucose in pancreatic β-cells. We investigated the impact of the SUR1 intron 16−3tc polymorphism on non-insulin-dependent diabetes mellitus (NIDDM) prevalence in a large representative sample of French men and women, 35–64 years old, and explored potential relationships between the SUR1 intron 16 −tc polymorphism and sulfonylurea therapy efficiency. This study took place in Lille (northern), Strasbourg (eastern), and Toulouse (southern France). One hundred and twenty-two subjects with NIDDM were registered. We stratified NIDDM subjects according to their medical treatment: sulfonylureas (n = 70) versus other treatments (n = 50). From the three populations, a control group was selected (n = 1,250). Subjects carrying the cc intron 16 genotype had an increased risk of NIDDM [odds ratio (OR) = 1.76, 95% confidence interval (CI) 1.10–2.80; P = 0.017]. Subjects bearing at least one −3c allele and treated with sulfonylurea agents had fasting plasma triglyceride concentrations 35% lower than subjects that were tt homozygous (P = 0.026), whereas no difference could be detected between genotypes in NIDDM subjects treated with other treatments. The SUR1 intron 16 −3tc polymorphism was associated with an increased susceptibility to NIDDM in this population study, and seems to modulate the sulfonylurea therapy efficiency on hypertriglyceridemia reduction. This observation may help to better target the various therapies available for treatment of NIDDM. © 2001 Wiley-Liss, Inc.

The ubiquitous form of the sodium–hydrogen exchanger, NHE1, is devoted to the regulation of intracellular pH and cell volume. In addition, NHE1 activity is stimulated by growth factors and increased NHE rates are found in both circulating and immortalized cells during diabetes or diabetic nephropathy. In this context, we searched for polymorphisms of the 5′-flanking regulatory region of NHE1 gene in subjects with type-I diabetes. We identified a C/T transition 696 bases upstream the translation initiation start site which disrupts a repeated palindromic GC sequence. The TT genotype was significantly more frequent in type-1 diabetics and may have functional importance. Genetic linkage between NHE1 and diabetes has been previously described in NOD mice strains with consequences on NHE rates. Hence, the polymorphism described hereby may act as a predisposition factor to type-I diabetes or to diabetic complications, and may be useful to investigate the genetic involvement of NHE1 in human pathophysiology.

OBJECTIVE Long-term experience of growth hormone (GH) replacement therapy in a large population of hypopituitary adults with GH deficiency (GHD) is limited, and safety surveillance is clearly essential. KIMS, the Pharmacia & Upjohn International Metabolic Database, is a long-term, open, outcomes research programme of hypopituitary adult patients with GHD who are treated in a conventional clinical setting. PATIENTS The present analysis encompasses data from 1034 hypopituitary adult GHD patients treated with GH for a total of 818 patient years. RESULTS Prior to GH therapy, the KIMS patient population exhibited an increased prevalence of obesity, diabetes mellitus (in females) and hyperlipidaemia, compared with normal populations described in published studies. Quality of life, assessed using a disease-specific questionnaire (QoL-AGHDA), was also reduced in KIMS patients. The maintenance dose of GH was significantly higher in patients who were receiving GH prior to enrolment into KIMS (non-naive patients) compared with patients who commenced GH at the time of enrolment (naive patients). In addition, dose of GH correlated significantly with body weight in the former group of patients. Analysis of serum levels of IGF-I indicated that overtreatment with GH was markedly more common in non-naive than in naive patients. The frequency of adverse events in KIMS patients was no higher than that reported in patients receiving placebo in previous clinical trials. Recurrence of pituitary or CNS tumours was reported in six patients, a rate consistent with data from control series. Three deaths were reported, none of which was obviously associated with GH treatment. CONCLUSIONS Our data, drawn from a large population of hypopituitary adults treated with GH for a total of more than 800 patient years, confirm previous reports that untreated GHD in hypopituitary adults is associated with a number of important clinical problems. In addition, the results suggest that there has been a shift in recent years from determination of GH dose on the basis of body weight to dose titration of individual patients, and indicate that the latter technique has important advantages. The data provide further evidence that GH replacement therapy is well-tolerated in adults. However, it is possible that some adverse events may not become evident over the time scale covered by the present analysis, and continued surveillance therefore remains mandatory.

OBJECTIVE: To compare the efficacy of 2 intensified insulin regimens, continuous subcutaneous insulin infusion (CSII) and multiple daily injections (MDI), by using the short-acting insulin analog lispro in type 1 diabetic patients. RESEARCH DESIGN AND METHODS: A total of 41 C-peptide-negative type 1 diabetic patients (age 43.5+/-10.3 years; 21 men and 20 women, BMI 24.0+/-2.4 kg/m2, diabetes duration 20.0+/-11.3 years) on intensified insulin therapy (MDI with regular insulin or lispro, n = 9, CSII with regular insulin, n = 32) were included in an open-label randomized crossover study comparing two 4-month periods of intensified insulin therapy with lispro: one period by MDI and the other by CSII. Blood glucose (BG) was monitored before and after each of the 3 meals each day. RESULTS: The basal insulin regimen had to be optimized in 75% of the patients during the MDI period (mean number of NPH injections per day = 2.65). HbA1c values were lower when lispro was used in CSII than in MDI (7.89+/-0.77 vs. 8.24+/-0.77%, P

OBJECTIVE To compare the efficacy of the short-acting insulin analog lispro (LP) with that of regular insulin in IDDM patients treated with an external pump. RESEARCH DESIGN AND METHODS Thirty-nine IDDM patients (age, 39.4 ± 1.5 years; sex ratio, 22M/17W; BMI, 24.4 ± 0.4 kg/m2; diabetes duration, 22.5 ± 1.6 years) who were treated by external pump for 5.1 ± 0.5 years were involved in an open-label, randomized, crossover multicenter study comparing two periods of 3 months of continuous subcutaneous insulin infusion with LP or with Actrapid HM, U-100 (ACT). Boluses were given 0–5 min (LP) or 20–30 min (ACT) before meals. Blood glucose (BG) was monitored before and after the three meals every day. RESULTS The decrease in HbA1c was more pronounced with LP than with ACT (−0.62 ± 0.13 vs. −0.09 ± 0.15%, P = 0.01). BG levels were lower with LP (7.93 ± 0.15 vs. 8.61 ± 0.18 mmol/l, P < 0.0001), particularly postprandial BG levels (8.26 ± 0.19 vs. 9.90 ± 0.20 mmol/l, P < 0.0001). Standard deviations of all the BG values (3.44 ± 0.10 vs. 3.80 ± 0.10 mmol/l, P = 0.0001) and of postprandial BG values (3.58 ± 0.10 vs. 3.84 ± 0.10 mmol/l. P < 0.02) were lower with LP. The rate of hypoglycemic events defined by BG < 3.0 mmol/l did not significantly differ between LP and ACT (7.03 ± 0.94 vs. 7.94 ± 0.88 per month, respectively), but the rate of occurrences of very low BG, defined as BG < 2.0 mmol/l, were significantly reduced with LP (0.05 ± 0.05 vs. 0.47 ± 0.19 per month, P < 0.05). At the end of the study, all but two (95%) of the patients chose LP for the extension phase. CONCLUSIONS When used in external pumps, LP provides better glycemic control and stability than regular insulin and does not increase the frequency of hypoglycemic episodes.

The passage of substances across the blood-brain barrier is regulated by cerebral capillaries which possess certain distinctly different morphological and enzymatic properties compared to capillaries of other organs. Investigations of the functional characteristics of brain capillaries have been facilitated by the use of cultured brain endothelial cells, but in most studies a number of characteristics of the in vivo system are lost. To provide an in vitro system for studies of brain capillary functions, we developed a method of isolating and producing a large number of bovine brain capillary endothelial cells. These cells, absolutely free of pericyte contamination, are subcultured, at the split ratio of 1:20 (20-fold increase of the cultured surface), with no apparent changes in cell morphology up to the fiftieth generation (10 passages). Retention of endothelial-specific characteristics (factor VIII-related antigen, angiotensin-converting enzyme, and nonthrombogenic surface) is shown for brain capillary-derived endothelial cells up to passage 10, even after frozen storage at passage 3. Furthermore, we showed that bovine brain capillary endothelial cells retain, up to the fiftieth generation, some of the characteristics of the blood-brain barrier: occurrence of tight junctions, paucity of pinocytotic vesicles, and monoamine oxidase activity.

Exposure of bovine vascular endothelial cell cultures to 25-hydroxycholesterol (50--100 microgram/ml) result in a 5--10-fold increase in cell surface binding sites of high density lipoprotein (HDL). This increase in HDL-binding sites was dependent on time and temperature. After a 48-h exposure to the oxygenated sterol, a maximal increase in HDL binding could be observed, and newly binding sites disappeared rapidly once 25-hydroxycholesterol was removed from the medium. No increase in HDL-binding sites was observed when cells were maintained at 4 degrees C. In contrast, cultures maintained at 37 degrees C did show an increase in HDL-binding sites when exposed to 25-hydroxycholesterol. Since simultaneous exposure of the cells to 25-hydroxycholesterol and cycloheximide resulted in an inhibition of HDL binding to the cells, it is suggested that de novo synthesis of HDL-binding sites is induced by 25-hydroxycholesterol. When the abilities of HDL2 and HDL3 to bind to newly synthesized HDL-binding sites were compared, HDL3 was found to bind more efficiently than HDL2. It is therefore unlikely that apoprotein E plays a major role in the binding of HDL to newly synthesized HDL-binding sites. When the properties of newly synthesized HDL-binding sites were analyzed, they were found to have a high affinity for HDL, since half-maximal binding was reached at a concentration as low as 5 microgram HDL protein/ml, and were saturable. Such HDL-binding sites had a relaxed specificity, since they were capable of binding low density liprotein (LDL). However, when LDL bound to newly synthesized HDL binding sites, it was no longer internalized, as reflected by a 90% reduction of LDL degradation, and instead of being cytotoxic it became mitogenic.

ONE of the objectives pursued actively for the past 80 years by cell biologists has been to reconstruct from single cells maintained in vitro the corresponding functional tissue. This not only requires that cells obtained from a given tissue and maintained singly in vitro proliferate actively but also that upon reaching confluence they reconstruct the tissue to which they belong in vivo in such a way that both the morphological characteristics of the tissue and its functions are preserved. In recent years, the discovery of mitogenic factors that maintained cells in an active stage of proliferation, thereby preventing their precocious senescence in vitro, has made it possible, in the case of a few tissues, to achieve these objectives. The discovery of growth factors is in a sense not a recent occurrence. The first growth factor to be identified was erythropoietin. This factor, first identified by Carnot and Deflandre in 1906, controls the proliferation of erythroblasts, the progenitors of red blood cells (...

Previous studies have shown that high-density lipoprotein (HDL) is mitogenic for low-density vascular endo thelial cell cultures. In contrast, low-density lipoprotein(LDL) at physiological concentration is cytotoxic for this cell type [Tauber et al. (1980) J.Clin.Invest. 66, 696-709]. In order to relate these observations to the physico-chemical events occurring after the interaction of these lipoproteins with the cells, we have studied the binding, internalization, and degradation of HDL as a function of cell density and organization and have compared the results to those obtained with LDL. Cultured vascular endothelial cells bind HDL to an extent which, on a molar basis, is similar to that of LDL. Since an 80% loss of the LDL receptor sites in cells that were preexposed to LDL was not associated with a detectable decrease in HDL binding, it is likely that HDL and LDL binding sites exist on the cell surface as distinct entities A 5-10 fold molar excess of LDL over 125 I-HDL was almost as effective as a similar excess of unlabeled HDL in reducing the binding of 125, indicationg that LDL can comete with HDL for HDL binding sites. In contrast, 125 I-LDL binding and uptake were reduced by less than 20% in the presence of a 50-fold molar excess of unlabeled HDL. Both uptake and degradation of HDL were 10-20 fold lower than those of LDL. HDL degradation was only slightly or not inhibited by chloroquine at a concentration which almost fully inhibited the degradation of LDL. Confluent and highly orgainized endothelial cell cultures bind HDL and LDL particles to an extent which is half of the amount bound to sparse or subconfluent culture However. The formation of a resting endothelial cell monlayer was associated with only a twofold decrease in the uptake of HDL, as compard to a 10-20-fold decrease in the uptake and degradation of LDL. In both sparse and confluent endothelial cultures, uptake via fluid pinocytosis non-specific adscorptive endocytosis could account for most of the HDL uptake. The different pathways of internalization of HDL when added at high concentration to sparse and actively growing cultures.

The growth-promoting activity of human high-density lipoproteins (HDL) and of their apolipoprotein components on bovine vascular endothelial cells in vitro has been compared. When maintained on plastic culture dishes and exposed to medium containing lipoprotein-deficient serum and fibroblast growth factor, these cells do not proliferate. Addition of either HDL or the total HDL apolipoproteins induces significant cell proliferation. Apolipoprotein C1, purified by chromatography on the ion-exchanger resin Polybuffer exchanger 94, has an effect on the cell growth similar to that of the total apolipoproteins of HDL.

Transforming Growth Factor-beta (TGF-beta) inhibits the serum and basic fibroblast growth factor (bFGF)-induced proliferation of cultured bovine retinal endothelial capillary (BREC) cells in a dose-dependent manner. The concentration of TGF-beta required to get half-maximal inhibition (ED50) are 10 pg ml-1 in serum and 17 pg ml-1 in the presence of additional bFGF (1 ng ml-1). These TGF-beta ED50 values are greatly increased when BREC cells were seeded at high density: 610 pg ml-1 in serum and 1 ng ml-1 in the presence of additional bFGF. At low initial cell density BREC cells are more sensitive to TGF-beta than aortic bovine arch endothelial (ABAE) cells for which TGF-beta ED50 values are respectively 40 pg ml-1 and 100 pg ml-1 in serum and in the presence of additional bFGF. In contrast, at high cell density BREC cells appeared to be more resistant to TGF-beta inhibition than ABAE cells for which TFG-beta ED50 values are 210 and 300 pg ml-1. Moreover bFGF added at increasing concentrations neutralize totally TGF-beta inhibition of BREC cell proliferation but only partially that of ABAE cell proliferation. Our results suggest a key role of equilibrium TFG-beta bFGF on the proliferation of BREC cells.

Adult bovine aortic endothelial (ABAE) cells, exposed to serum-free medium, specifically bind 125I-labeled human high-density lipoprotein (125I-HDL). Addition of human lipoprotein-deficient serum (LPDS) reduces the specific binding of 125I-HDL in a concentration-dependent manner, such that LPDS at a concentration of 6 mg protein/ml almost completely inhibits the specific binding of 125I-HDL. ABAE cultures exposed to 125I-labeled LPDS (125I-LPDS) specifically bind two peptides, which appear as minor iodinated components in 125I-LPDS. The binding of these two components is abolished in the presence of excess amounts of unlabeled LPDS or HDL. Preincubation of ABAE cells with 25-hydroxycholesterol (25-HC) results in an increase in the binding of the two 125I-LPDS components, similar to the increase observed in 125I-HDL binding in the presence of 25-HC. These two LPDS components comigrate on sodium dodecyl sulfate/polyacrylamide gel electrophoresis (SDS-PAGE) with apolipoproteins A-I and A-IV of molecular masses 28 kDa and 43 kDa respectively. Furthermore, these two proteins were transferred from the SDS gel to nitrocellulose paper and interacted specifically with anti-(A-I) and anti-(A-IV) sera respectively. When ABAE cultures, pretreated with 25-HC in the presence of LPDS, are subjected to cell-surface iodination, the A-IV appears as one of the major proteins on the cell surface accessible to iodination. The interaction of A-IV with the cell surface of 25-HC-treated cells is not specific to ABAE cells and appears also in human skin fibroblasts. Analysis of the relative amounts of various apolipoproteins in the 125I-HDL bound to ABAE cells demonstrates a decrease in the relative amount of iodinated A-II concomitant with increase in the relative amounts of the other iodinated apolipoproteins, when compared to the composition of the native 125I-HDL. These changes are similar whether the binding is done in the presence or absence of LPDS. It indicates that the decrease in 125I-HDL binding in the presence of LPDS is not due to displacement of the iodinated apolipoproteins A-I and A-IV in the 125I-HDL by unlabeled A-I and A-IV present in LPDS. The results indicate that free apolipoproteins A-I and A-IV, present in LPDS, can displace HDL on the cell surface of ABAE cells. Thus, free A-I and A-IV, present in plasma, control the binding of HDL to endothelial cells and may regulate the process of cholesterol removal from the cells performed by HDL.

Fibroblast growth factors (FGFs) are mitogenic for bovine retinal capillary endothelial cells (BREC) seeded at a low density. Seeding BREC cells at a high density greatly reduces their requirement for basic FGF (bFGF) in order to proliferate actively. We show here that monolayers of BREC cells synthesize and release into the culture medium a growth factor, which on the basis of biological activity, heparin affinity, immuno-cross reactivity with anti-bFGF antibodies and mRNA analysis, has been identified as basic fibroblast growth factor. These data indicate that BREC cells are able to synthesize and release bFGF, which can act as a promoting-growth factor for these cells by a para- and/or autocrine mechanism. We suggest thus, that this para- and/or autocrine mechanism involving bFGF may play a key role in preretinal neovascularization, particularly in diabetic patients presenting a proliferative retinopathy.

The cellular action of growth factors, among them basic fibroblast growth factor (bFGF), is mediated by their interaction with a cell surface receptor, but the mechanism of transfer of mitogenic (or other) signals to the nucleus has not been identified. In this work, we show that bFGF is translocated to and accumulated in the nucleolus. Furthermore, the nucleolar localization of bFGF is correlated with a stimulation of transcription of ribosomal genes during G0----G1 transition induced by bFGF alone in adult bovine aortic endothelial cells (ABAE cells). Stimulation of ribosomal gene transcription is preceded by a significant increase of the major nonhistone nucleolar protein, nucleolin. In vitro, the growth factor has a direct effect on the enhancement of RNA polymerase I activity in isolated nuclei from quiescent sparse (G0) ABAE cells. The direct action of bFGF on the level of ribosomal gene transcription could correspond to an additional growth-signaling pathway, mediated by this growth factor.