bluuebunny/crossref_metadata_2025 huggingface dataset:
Correlates of endothelial function and their relationship with inflammation in patients with familial hypercholesterolaemia
Authors: HAELST Paul L. van , DOORMAAL Jasper J. van , ASSELBERGS Folkert W. , ROON Arie M. van , VEEGER Nic J. G. M. , HENNEMAN Maureen M. , SMIT Andries J. , TERVAERT Jan Willem COHEN , MAY Johan F. , GANS Rijk O. B.
Published: September 2003

Atherosclerosis is characterized by a low-grade systemic inflammatory response and endothelial dysfunction. The aim of the present study was to investigate a possible relationship between systemic markers of inflammation, serum markers of endothelial activation and endothelium-dependent vasodilatation in a group of high-risk patients, and to evaluate the effects of intervention with high doses of simvastatin on these parameters. In patients with heterozygous familial hypercholesterolaemia, without atherosclerotic events, flow-mediated vasodilatation (FMD) of the brachial artery was measured after a wash-out period for lipid-lowering drugs (baseline) and after 6 weeks of treatment with simvastatin 80 mg daily. Levels of C-reactive protein (CRP), soluble intercellular cell-adhesion molecule (s-ICAM) and soluble E-selectin (s-E-selectin) were determined at baseline and again after 6 weeks and 12 months of therapy. A total of 35 subjects participated in the study (mean age 42 years; 60% male). When divided into tertiles according to FMD (<3.9%, 3.9–9.0% and >9.0%), no differences in levels of CRP, s-ICAM-1 and/or s-E-selectin were detected between the groups. Moreover, no changes in FMD, levels of CRP or levels of s-ICAM-1 and/or s-E-selectin were found during treatment with simvastatin. We conclude that endothelial function, as reflected by FMD, does not seem to be related to markers of inflammation in familial hypercholesterolaemia subjects at high risk of, but without clinically overt signs of, atherosclerosis. Moreover, aggressive lipid-lowering therapy with simvastatin does not result in improved endothelial function or in a reduction of markers of inflammation in these patients.
Effects of incremental levels of continuous positive airway pressure on cerebral blood flow velocity in healthy adult humans
Authors: SCALA R. , TURKINGTON P. M. , WANKLYN P. , BAMFORD J. , ELLIOTT M. W.
Published: September 2003

Sleep disordered breathing is common in patients with cerebrovascular disease, and could exacerbate the cerebral damage in acute stroke. Data about the effects of continuous positive airway pressure (CPAP) upon cerebral perfusion are conflicting. We investigated whether increasing levels of CPAP may affect cerebral haemodynamics, assessed by transcranial Doppler (TCD) in normal humans. A group of 25 healthy young volunteers were evaluated before (CPAP0-pre), during (CPAP5, CPAP10 and CPAP15, denoting CPAP at 5, 10 and 15 cmH2O respectively) and after (CPAP0-post) application of incremental levels of CPAP delivered through a mouthpiece. The mean cerebral blood flow velocity (CBFV) and the pulsatility index (PI; an indirect measure of cerebrovascular resistance) in the middle cerebral artery were measured with TCD. Respiratory rate, heart rate, end-tidal carbon dioxide pressure (PETCO2), transcutaneous haemoglobin oxygen saturation (SpO2), mean arterial blood pressure and anxiety score were also recorded. Compared with CPAP0-pre, CBFV was significantly decreased as higher levels of CPAP were applied (P<0.0001). CPAP15 increased PI (P<0.05), PETCO2 was reduced by CPAP10 and CPAP15 (P<0.0001), and anxiety score and SpO2 increased at all levels of CPAP (P<0.05). Heart rate, respiratory rate and mean arterial pressure did not change. The decrease in CBFV was correlated with the fall in PETCO2 (CPAP15) and the increase in PI (CPAP10, CPAP15) (P<0.05). In conclusion, even low levels of CPAP delivered through a mouthpiece in awake, young volunteers led to a decrease in CBFV, measured by TCD. This fall in CBFV was associated with hypocapnia and with an increase in both cerebrovascular resistance and anxiety due to breathing against positive pressure. As the negative consequences of a fall in CBFV may outweigh the therapeutic effects of CPAP in the post-stroke setting, further studies of the cerebrovascular effects of CPAP with different interfaces in elderly patients with and without stroke are needed before intervention trials can be performed safely.
Gene therapy for ocular angiogenesis
Authors: BAINBRIDGE James W. B. , MISTRY Ajay R. , THRASHER Adrian J. , ALI Robin R.
Published: September 2003

Ocular neovascularization is a central feature of diabetic retinopathy and age-related macular degeneration. These conditions are the major causes of blindness in the developed world. Current treatments are of limited efficacy and associated with significant adverse effects. Characterization of the molecular and cellular events involved in angiogenesis has led to the identification of a number of angiostatic molecules with potential therapeutic value. The systemic administration of small molecule angiostatic proteins risks significant systemic adverse effects and the effect of their intraocular injection is short-lived. Local gene transfer, however, offers the possibility of targeted, sustained and regulatable delivery of angiostatic proteins to the retina after a single procedure to introduce a vector to an intraocular site. The effect of intra-ocular delivery of recombinant viruses carrying genes encoding angiostatic proteins has been demonstrated in rodent models of ocular neovascularization. Recombinant adeno-associated virus-mediated local gene transfer of a vascular endothelial growth factor inhibitor controls both retinal and choroidal neovascularization. The clinical application of this approach may require the means to regulate gene expression in order to minimize the potential for adverse effects. Regulation of transgene expression by means of a hypoxia-responsive promoter offers an attractive strategy for the targeted and regulated delivery of angiostatic proteins to the retina in the management of ischaemia-induced ocular neovascularization. Preclinical studies of gene transfer in a large animal model following subretinal delivery of a recombinant adeno-associated virus vector have demonstrated efficient sustained reporter gene expression in cells of the outer retina. Recent progress has enabled the planning of clinical trials of gene therapy for ocular neovascular disorders.
Cerebrospinal fluid levels of catechols in patients with neurogenic orthostatic hypotension
Authors: GOLDSTEIN David S. , HOLMES Courtney , PATRONAS Nicholas , KOPIN Irwin J.
Published: September 2003

In multiple system atrophy (MSA) and pure autonomic failure (PAF), orthostatic hypotension (OH) results from deficient noradrenaline release from sympathetic nerves during standing. Post-mortem findings have indicated loss of central noradrenergic cells in both diseases. The present study sought in vivo neurochemical evidence for central noradrenergic deficiency in patients with OH due to MSA or PAF. A total of 28 patients with OH (18 with MSA; 10 with PAF) had cerebrospinal fluid and blood sampled for levels of noradrenaline and its neuronal metabolite dihydroxyphenylglycol. A control group of 44 subjects included 10 elderly normal volunteers, 10 patients with Alzheimer's disease, 18 patients with dysautonomia (postural tachycardia syndrome or neurocardiogenic syncope) and six patients with MSA in the absence of OH. Patients with OH had lower cerebrospinal fluid concentrations of noradrenaline (0.53±0.07 nmol/l) and dihydroxyphenylglycol (6.52±0.46 nmol/l) than did control subjects (0.90±0.09 and 9.64±0.46 nmol/l respectively; P=0.0001). The MSA + OH group had higher plasma levels of both catechols (noradrenaline, 1.31±0.16 nmol/l; dihydroxyphenylglycol, 5.08±0.43 nmol/l) than did the PAF group (noradrenaline, 0.38±0.08 nmol/l; dihydroxyphenylglycol, 2.53±0.30 nmol/l; P<0.001), despite similarly low cerebrospinal fluid levels. Among MSA patients, those with OH had lower cerebrospinal fluid levels of noradrenaline and dihydroxyphenylglycol than those without OH (noradrenaline, 1.71±0.64 nmol/l; dihydroxyphenylglycol, 10.41±1.77 nmol/l respectively; P=0.006). The findings are consistent with central noradrenergic deficiency in both MSA + OH and PAF. In MSA, central noradrenergic deficiency seems to relate specifically to OH.
Decreased insulin sensitivity during dietary sodium restriction is not mediated by effects of angiotensin II on insulin action
Authors: PERRY Colin G. , PALMER Tim , CLELAND Steven J. , MORTON Ian J. , SALT Ian P. , PETRIE John R. , GOULD Gwyn W. , CONNELL John M. C.
Published: September 2003

We have previously reported that modest dietary sodium restriction, as advocated in management guidelines for diabetes, may reduce insulin sensitivity. It has since been suggested that this effect may be mediated via cross-talk between insulin and angiotensin II (AII)-stimulated intracellular second messengers. In order to assess the effect of 5 days of modest sodium restriction (to <80 mmol/day target sodium intake) on insulin sensitivity, 15 healthy males underwent a double-blind, placebo-controlled, randomized, cross-over euglycaemic hyperinsulinaemic clamp study. One phase was supplemented with sodium tablets and the other with matched placebo. Insulin sensitivity (M) was reduced during dietary sodium restriction [median M value, 10.2 mg/kg per min (interquartile range 9.50–13.85) versus 12.8 mg/kg per min (interquartile range 9.60–14.30), P<0.05]. To elucidate potential mechanisms that may explain this observation, we investigated the effect of AII on insulin action in isolated adipocytes obtained from healthy females. No effect of AII on insulin-mediated glucose transport or suppression of lipolysis was observed. In conclusion, despite the observation that dietary sodium restriction was associated with a median 15% reduction in insulin sensitivity, we found no evidence of a direct effect of AII on insulin action in human adipocytes.
Apolipoprotein E gene polymorphism and colorectal cancer: gender-specific modulation of risk and prognosis
Authors: WATSON Mark A. , GAY Laura , STEBBINGS William S. L. , SPEAKMAN Chris T. M. , BINGHAM Sheila A. , LOKTIONOV Alexandre
Published: September 2003

Apolipoprotein E (ApoE) gene polymorphism is a major factor in lipid metabolism. It has been suggested that this polymorphism can modulate colorectal tumour risk. We tested this hypothesis for colorectal cancer (CRC). ApoE genotype was determined in 206 patients with CRC and 353 healthy controls from the East Anglia region of the U.K. Compared with individuals possessing the most common ɛ3/ɛ3 genotype, those with the ɛ2/ɛ3 genotype had an increased risk of colon cancer [odds ratio (OR) = 1.91; 95% confidence interval 1.05–3.45]. However, this association was strongly affected by gender. Separate analysis of male and female subjects revealed a highly significant association in men (OR = 2.71; 95% confidence interval 1.30–5.65), but no association in women (OR = 1.01; 95% confidence interval 0.37–2.77). Likewise, the proportion of male patients with more advanced tumours (Dukes' C&D) was significantly increased among those with the ApoE ε2/ε3 genotype (OR = 4.16; 95% confidence interval 1.36–12.75). No significant effect of the presence of the ε4 allele on CRC risk was found; however, there were no ε4/ε4 homozygotes among patients with proximal colon cancers. The ApoE ε3/ε3 majority genotype appeared to be associated with the lowest risk of CRC. These results suggest that ApoE genotype can influence both CRC risk and prognosis of the existing disease in a gender-dependent manner.
Ethnic differences in circulating soluble adhesion molecules: the Wandsworth Heart and Stroke Study
Authors: MILLER Michelle A. , SAGNELLA Giuseppe A. , KERRY Sally M. , STRAZZULLO Pasquale , COOK Derek G. , CAPPUCCIO Francesco P.
Published: September 2003

The aim of this study was to investigate whether soluble adhesion molecule levels differ by ethnic group. Soluble plasma adhesion molecules [soluble P-selectin (sP-selectin), soluble E-selectin (sE-selectin), soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1)] were measured in 261 white (120 females), 188 African origin (99 females) and 215 South Asian (99 females) individuals living in England. All were free from coronary heart disease, stroke and other cardiovascular disease, diabetes, drug therapy for hypertension or high lipids, hormone-replacement therapy or oral contraceptive pill. The results of the study indicated that there were important differences in the levels of adhesion molecules by sex and smoking. However, when adjusting for these and other potential confounders, there were no differences in levels between white subjects and individuals of South Asian origin. In contrast, people of African origin had significantly lower levels of sICAM-1 [Caribbean -30% (-36 to -23%); West African -22% (-29 to -15%), values are means (95% confidence intervals)], sVCAM-1 [Caribbean -14% (-19 to -8%); West African -10% (-17 to -3%)] and sP-selectin [Caribbean -10% (-17 to -2%); West African -24% (-31 to -16%)] than white individuals. In conclusion, circulating levels of some soluble adhesion molecules are lower in individuals of Caribbean or West African origin compared with white or South Asian individuals. These relationships may contribute to the low risk of coronary heart disease seen in people of African origin living in England.
Detection and analysis of urinary peptides by on-line liquid chromatography and mass spectrometry: application to patients with renal Fanconi syndrome
Authors: CUTILLAS Pedro R. , NORDEN Anthony G.W. , CRAMER Rainer , BURLINGAME Alma L. , UNWIN Robert J.
Published: September 2003

Urinary proteomics has become a topical and potentially valuable field of study in relation to normal and abnormal renal function. Filtered bioactive peptides present in high concentration in the nephron of patients with tubular proteinuria may have downstream effects on renal tubular function. In renal Fanconi syndromes, such as Dent's disease, peptides implicated in altered tubular function or injury have recently been measured in urine by immunochemical methods. However, the limited availability of antibodies means that only certain peptides can be detected in this way. We have used nanoflow liquid chromatography and tandem mass spectrometry (nanoLC-MS/MS) as a complementary technique to analyse urinary peptides. Urine was desalted by solid-phase extraction (SPE) and its peptides were then separated from neutral and acidic compounds by strong cation-exchange chromatography (SCX), which was also used to fractionate the peptide mixture. Fractions from the SCX step were separated further by reversed-phase LC and analysed on-line by MS/MS. Extraction by SPE showed a good recovery of small peptides. We detected over 100 molecular species in urine samples from three individuals with Dent's disease. In addition to plasma and known urinary proteins, we identified some novel proteins and potentially bioactive peptides in urine from these patients, which were not present in normal urine. These data show that nanoLC-MS/MS complements existing techniques for the identification of polypeptides in urine. This approach is a potentially powerful tool to discover new markers and/or causative factors in renal disease; in addition, its sensitivity may also make it applicable to the direct ultramicroanalysis of renal tubule fluid.
Chronic fatigue syndrome: new evidence for a central fatigue disorder
Authors: GEORGIADES Evelina , BEHAN Wilhelmina M. H. , KILDUFF Liam P. , HADJICHARALAMBOUS Marios , MACKIE Eileen E. , WILSON John , WARD Susan A. , PITSILADIS Yannis P.
Published: September 2003

Considerable evidence points towards a prominent role for central nervous system (CNS) mechanisms in the pathogenesis of chronic fatigue syndrome (CFS), a disorder characterized chiefly by persistent, often debilitating, fatigue. We wished to characterize circulating profiles of putative amino acid modulators of CNS 5-hydroxytryptamine (5-HT; serotoninergic) and dopaminergic function in CFS patients at rest, as well as during symptom-limited exercise and subsequent recovery. Groups of 12 CFS patients and 11 age- and sex-matched sedentary controls, with similar physical activity histories, underwent ramp-incremental exercise to the limit of tolerance. Plasma amino acid concentrations, oxygen uptake and ratings of perceived exertion were measured at rest, and during exercise and recovery. Peak oxygen uptake was significantly lower in the CFS patients compared with controls. Rating of perceived exertion in the patients was higher at all time points measured, including at rest, relative to controls. Levels of free tryptophan (free Trp), the rate-limiting 5-HT precursor, were significantly higher in CFS patients at exhaustion and during recovery, whereas concentrations of branched-chain amino acids (BCAA) and large neutral amino acids (LNAA) were lower in CFS patients at exhaustion, and for LNAA also during recovery. Consequently, the [free Trp]/[BCAA] and [free Trp]/[LNAA] ratios were significantly higher in CFS patients, except at rest. On the other hand, levels of tyrosine, the rate-limiting dopaminergic precursor, were significantly lower at all time points in the CFS patients. The significant differences observed in a number of key putative CNS 5-HT and dopaminergic modulators, coupled with the exacerbated perception of effort, provide further evidence for a potentially significant role for CNS mechanisms in the pathogenesis of CFS.
Renal function and angiotensin AT1 receptor expression in young rats following intrauterine exposure to a maternal low-protein diet
Authors: SAHAJPAL Vandana , ASHTON Nick
Published: September 2003

Recent studies have proposed a link between impaired nephrogenesis, decreased activity of the renin–angiotensin system and the onset of hypertension in rats exposed in the uterus to a maternal low-protein diet. However, there is no detailed information about renal function in this model; hence the aim of the present study was to assess renal function in young (4-week-old) rats exposed in the uterus to a maternal low-protein diet. Pregnant Wistar rats were fed isocalorific diets containing either 18% (normal protein; offspring denoted NP rats) or 9% (low protein; offspring denoted LP rats) (w/w) protein from conception until birth. At 4 weeks of age, male offspring were anaesthetized and prepared for the study of renal function, during which animals received saline alone, a bolus of enalapril (5 mg·kg-1) or a bolus of enalapril followed by an infusion of angiotensin II (30 ng·min-1·kg-1). Under control conditions, renal haemodynamic and tubular function did not differ. However, when challenged with angiotensin II, LP rats responded with a greater decrease in glomerular filtration rate than did NP rats [NP, 2.0±0.2 ml·min-1·g-1 kidney weight (n=9); LP, 1.0±0.2 ml·min-1·g-1 kidney weight (n=5); P<0.05]. Renal electrolyte excretion did not differ. LP rats had significantly fewer glomeruli than NP rats (P<0.01). Renal angiotensin II AT1 receptor expression was increased (P<0.01) by 24% in LP rats. It is concluded that blood pressure may be elevated in LP rats in order to maintain glomerular filtration rate against a background of fewer nephrons. Increased AT1 receptor expression, which may arise as a result of the direct effect of protein restriction or in response to the reported decrease in renal tissue angiotensin II concentration, could also contribute to the elevated blood pressure of this model.
Beyond lysis: how complement influences cell fate
Authors: COLE Duncan S. , MORGAN B. Paul
Published: September 2003

Complement is a central component of the innate immune system involved in protection against pathogens. For many years, complement has been known to cause death of targets, either indirectly by attracting and activating phagocytes or directly by formation of a membrane pore, the membrane attack complex. More recently, it has been recognized that complement may cause other ‘non-classical’ effects that may not directly be aimed at killing of pathogens. Products of complement activation collaborate with the adaptive immune system to enhance responses to antigens. The membrane attack complex of complement, apart from lysing cells, can also trigger diverse events in target cells that include cell activation, proliferation, resistance to subsequent complement attack and either resistance to, or induction of, apoptosis. Various complement products play important roles in signalling for clearance by phagocytes of apoptotic self cells. Here we review some of these non-classical activities of complement and stress the roles that they may play in maintaining the integrity of the organism.
Perception of bronchoconstriction in obstructive pulmonary diseases (disease-specific dyspnoea)
Authors: EKICI Aydanur , YILMAZ Sevda , EKICI Mehmet , KALPAKLIOĞLU Füsun , KARADENIZ Yasemin , ARSLAN Mesut , ITEGINLI Ahmet , KARA Turkan , KURTIPEK Ercan
Published: September 2003

The perception of dyspnoea differs between subjects with obstructive pulmonary diseases, partly because the underlying mechanisms for bronchoconstriction are different. We investigated the perception of bronchoconstriction in subjects with bronchiectasis, asthma and chronic bronchitis and possible contributing factors. Forty-seven non-smoking subjects with bronchiectasis, 50 subjects with asthma and 31 with chronic bronchitis were challenged with histamine. The Borg score was assessed before and after each challenge. The perception score corresponding to a fall in the forced expiratory volume in 1 s (FEV1) by 20% (PS20) was calculated. The mean values of ΔBorg/ΔFEV1 (the Borg score change divided by the change in FEV1 as a percentage of the baseline FEV1) and PS20 of subjects with bronchiectasis and chronic bronchitis were significantly lower than in subjects with asthma after histamine challenge. The ratio of non-perceivers was higher in bronchiectasis (25.5%) and in chronic bronchitis (32.3%) than in asthma (4.0%). When all subjects were considered, ΔBorg/ΔFEV1 values were significantly related to female sex (r2=11.5%, P=0.0001), but not to age, duration of the disease, PD20 or baseline FEV1%. The present study indicates that perception of histamine-induced bronchoconstriction is lower in patients with bronchiectasis and chronic bronchitis than in asthmatic patients, and that sex partially contributes to this difference.
Higher prevalence of Chlamydia pneumoniae seropositivity in Finnish twins compared with co-twins living in Sweden: relationships with markers of subclinical atherosclerosis
Authors: JARTTI Laura , RAITAKARI Olli T. , JÄRVISALO Mikko J. , HAMMAR Niklas , KAPRIO Jaakko , KOSKENVUO Markku , MARNIEMI Jukka , SAIKKU Pekka , RÖNNEMAA Tapani
Published: September 2003

Mortality rates from coronary heart disease are lower in Swedish men and among Finnish migrants who have lived in Sweden for over 20 years than in men living in Finland. Sero-epidemiological studies, investigations of atheromatous plaque specimens, in vitro animal models and anti-chlamydial antibiotic trials have given support to the hypothesis that Chlamydia pneumoniae (Cpn) has a role in atherosclerosis. We investigated whether men with a similar genetic background but living permanently in Finland or Sweden have differences in the prevalence of Cpn seropositivity, and whether chronic Cpn infection is associated with markers of subclinical atherosclerosis. We measured anti-Cpn antibodies and ultrasonographic markers of subclinical atherosclerosis, including carotid intima-media thickness, carotid artery compliance and brachial artery flow-mediated dilatation, in a population of 76 migrant-discordant male twin pairs (152 men). The number of men with seropositivity to Cpn infection (defined as IgA⩾1:64 and IgG⩾1:128) was greater in Finland than in Sweden (21.5% compared with 10.5%; P=0.046). Cpn seropositivity accompanied by elevated C-reactive protein (CRP) levels (>1 mg/l) was associated with attenuated brachial artery flow-mediated dilatation (3.3±0.3%, compared with 5.5±0.4% in men with no signs of Cpn infection; P<0.001).Thus, among Finnish twin brothers discordant for migration to Sweden, the prevalence of Cpn seropositivity is higher for those living in Finland, and men with Cpn seropositivity combined with elevated CRP levels had attenuated endothelial function. These findings offer insight into the mechanism whereby chronic Cpn infection may increase the risk of coronary heart disease.
Estimation of central aortic pressure by SphygmoCor® requires intra-arterial peripheral pressures
Authors: CLOUD Geoffrey C. , RAJKUMAR Chakravarthi , KOONER Jaspal , COOKE Jonathan , BULPITT Christopher J.
Published: September 2003

Central arterial pressure, measured close to the heart, may be of more patho-physiological importance than conventional non-invasive cuff blood pressure. The technique of applanation tonometry using SphygmoCor® has been proposed as a non-invasive method of estimating central pressure. This relies on mathematically derived generalized transfer functions, which have been previously validated using invasive peripheral pressure measurements. We compared simultaneous estimates of central aortic pressure using this technique with those measured directly during the routine diagnostic cardiac catheterization of 30 subjects (age range 27–84 years), half of whom were aged 65 years or more. This was done by applanating the left radial artery and recording the non-invasive brachial cuff blood pressure to generate a central aortic pressure estimate, using the SphygmoCor® radial transfer function. The comparative results were analysed using Bland—Altman plots of mean difference. SphygmoCor®, on average, underestimated systolic central arterial pressure by 13.3 mmHg and overestimated diastolic pressure by 11.5 mmHg. The results were similar in patients aged under and above 65 years. Furthermore, non-invasively measured brachial pressures were seen to give an overall closer estimate of the central arterial pressure than the SphygmoCor® system. The transfer function has been validated from invasively measured arterial pressures and the current use by the system of non-invasive measures may explain the discrepancies. However, age, drugs and arterial disease would also be expected to play a role.
Effect of epidermal growth factor administration on intestinal cell proliferation, crypt fission and polyp formation in multiple intestinal neoplasia (Min) mice
Authors: BASHIR O. , FITZGERALD A. J. , BERLANGA-ACOSTA J. , PLAYFORD R. J. , GOODLAD R. A.
Published: September 2003

Recombinant epidermal growth factor (EGF) may be useful to treat severe ulcerative gastrointestinal injury. There is concern, however, that systemic use of this potent mitogen might increase tumour development and/or progression in susceptible subjects. We therefore examined the effect of chronic administration of systemic EGF to multiple intestinal neoplasia (Min) mice, who have a genetic defect in the adenomatous polyposis coli (APC) gene, leading to increased polyp development. Min mice (n=26) and wild-type littermates (n=26) received saline or EGF (223 μg of EGF/kg per day) for 4 weeks using subcutaneous osmotic mini-pumps. Cell proliferation and crypt fission were analysed using microdissection techniques and the number and size of polyps in the small and large intestines were determined. EGF increased wet weight and crypt cell proliferation rate by approx. 20% (all P<0.01 compared with the relevant control) in the small intestine and colon of both control and Min mice. In both groups, EGF reduced the colonic fission index by approx. 40% (P<0.01), but did not affect crypt fission in the small intestine. In Min mice, administration of EGF did not increase numbers of polyps or degree of dysplasia, but resulted in a 40% increase in the polyp size in the proximal intestine (P<0.02), but not in the remainder of the small intestine or colon. No polyps were found in control mice given EGF. EGF did not initiate polyp formation in control or Min mice. However, as polyp size is an important determinant for subsequent risk of malignant change in human colon cancer, further studies appear justified.
Increased expression of angiopoietin-2 and Tie2 receptor in a rat model of myocardial ischaemia/reperfusion
Authors: SHYU Kou-Gi , CHANG Chih-Chuan , WANG Bao-Wei , KUAN Peiliang , CHANG Hang
Published: September 2003

The angiopoietins and Tie receptors are involved in blood vessel formation. The role of the angiopoietin/Tie receptor system in myocardial ischaemia/reperfusion is not well known. To investigate the participation of angiopoietins and Tie receptors in myocardial ischaemia/reperfusion, adult Wistar rats were studied in which the left coronary artery was ligated for 30 min, followed by reperfusion. Angiopoietin-1 (Ang1), angiopoietin-2 (Ang2), Tie1 and Tie2 were measured immediately after relief of occlusion, and 1, 6, 24 and 72 h after reperfusion, by Northern blot, Western blot and immunohistochemical staining. Ang2 mRNA was increased significantly at 24 h and 48 h after reperfusion, and returned to baseline levels at 72 h, in the jeopardized myocardium. Tie2 mRNA increased 3.4-fold immediately after the relief of occlusion, reached a maximum 8-fold increase at 24 h after reperfusion and remained elevated up to 72 h. Ang2 protein levels also increased after reperfusion, reaching a maximum 2.2-fold increase at 48 h after reperfusion. Tie2 protein increased immediately after relief of ischaemia, and showed a significant increase from 6 h to 72 h after reperfusion as compared with the sham control. Ang1 and Tie1 mRNA and protein did not show significant changes after ischaemia/reperfusion. Immunohistochemical studies also showed increased immunoreactivity of Ang2 and Tie2 in the jeopardized myocardium after ischaemia/reperfusion. In conclusion, expression of both Ang2 and Tie2 increased after ischaemia/reperfusion in the rat ventricular myocardium, while the expression of Ang1 and Tie1 did not.
Reduction in hepatic endothelin-1 clearance in cirrhosis
Authors: DUC Anh Thu TRAN , SCHWAB Andreas J. , SIMARD André , VILLENEUVE Louis , DUPUIS Jocelyn
Published: September 2003

Circulating endothelin-1 (ET-1) levels are increased in cirrhosis. The liver is an important site for circulating ET-1 clearance through the ETB receptor. We evaluated ET-1 kinetics in cirrhosis to determine if a reduced liver clearance contributes to this process. Cirrhosis was induced by carbon tetrachloride in rats. Hepatic ET-1 clearance was measured in isolated perfused livers using the single bolus multiple indicator-dilution technique. Plasma ET-1 levels doubled in cirrhosis from 0.49±0.04 fmol/ml (mean±S.E.M.) to 1.0±0.18 fmol/ml (P<0.01). Liver ET-1 extraction was reduced from 81±1% (mean±S.E.M.) in controls to 50±6% in cirrhosis (P<0.01). Kinetic modelling revealed a major irreversible binding site for ET-1 that is blocked by the selective ETB receptor antagonist BQ788 and a minor non-specific reversible binding site that cannot be blocked with BQ788 or the selective ETA antagonist BQ123. Reduced hepatic clearance correlated with the biochemical markers of cirrhosis, portal vein perfusion pressure (r=-0.457; P<0.001) and the increase in ET-1 levels (r=-0.462; P=0.002). Immunohistofluorescence with specific anti-(ETB receptor) antibodies revealed a preponderant distribution of ETB receptors on hepatic stellate cells, which was increased in cirrhosis. We conclude that cirrhosis reduces ET-1 clearance probably by capillarization of hepatic sinusoids and reduced access to ETB receptors. This relates to the severity of cirrhosis and may contribute to the increase in circulating ET-1 levels.
Periodontal disease is associated with lower antioxidant capacity in whole saliva and evidence of increased protein oxidation
Authors: SCULLEY Dean V. , LANGLEY-EVANS Simon C.
Published: September 2003

The aim of this cohort study was to determine whether periodontitis and gingivitis are associated with impaired salivary antioxidant status and increased oxidative injury. One hundred and twenty-nine patients attending a routine dental check-up were recruited for the study. Periodontal disease status was characterized using the Community Periodontal Index of Treatment Needs (CPITN) system. Total salivary antioxidant capacity and salivary ascorbate, urate and albumin were determined in a sample of whole unstimulated saliva. Protein carbonyl concentrations were determined as an index of oxidative injury. Patients in the lowest tertile of CPITN score exhibited decreased salivary delivery of antioxidants and specifically urate than patients in the upper tertile. Poor periodontal health was associated with increased concentrations of protein carbonyls in saliva. Women had significantly lower total antioxidant status than men, regardless of periodontal health. Periodontal disease is associated with reduced salivary antioxidant status and increased oxidative damage within the oral cavity.
Up-regulation of vascular and renal mitogen-activated protein kinases in hypertensive rats is normalized by inhibitors of the Na+/Mg2+ exchanger
Authors: TOUYZ Rhian M. , YAO Guoying
Published: September 2003

In the present in vivo study, we have investigated whether inhibitors of the Na+/Mg2+ exchanger quinidine and imipramine influence the development of hypertension and whether this is associated with modulation of mitogen-activated protein (MAP) kinase activation in arteries and kidneys of hypertensive rats. Sprague—Dawley rats were divided into four groups (n=6/group): control (vehicle), angiotensin II (Ang II; 150 ng/kg of body weight per min subcutaneously), quinidine [Ang II (150 ng/kg of body weight per min)+quinidine (5 mg/kg of body weight per day in food)] and imipramine groups [Ang II (150 ng/kg of body weight per min)+imipramine (5 mg/kg/day in food)]. Rats were studied for 3 weeks. Phosphorylation of vascular and renal extracellular-signal-regulated protein kinase 1/2 (ERK1/2), p38MAP kinase and c-Jun N-terminal kinase (JNK) were assessed using phospho-specific antibodies. Ang II increased systolic blood pressure from 112±5 mmHg to 215±9 mmHg (P<0.01). Development of hypertension was attenuated in Ang II-infused rats treated with quinidine (173±6 mmHg) and imipramine (152±6 mmHg) (P<0.01). Phosphorylation of ERK1/2, p38MAP kinase and JNK, which were increased 2–3-fold in arteries of the Ang II group, were reduced by quinidine and imipramine (P<0.05). Activation of renal MAP kinases was also increased in the Ang II group (P<0.05). Quinidine and imipramine reduced the phosphorylation of renal ERK1/2, but did not modify renal p38MAP kinase or JNK. Our data demonstrate that Ang II induces severe hypertension in Sprague—Dawley rats and this is associated with increased phosphorylation of vascular and renal MAP kinases. Quinidine and imipramine attenuated the development of hypertension and normalized MAP kinase activity. The findings from this study suggest a possible role for the Na+/Mg2+ exchanger in vascular signalling events associated with blood pressure elevation in Ang II-dependent hypertension.
Chylomicron-remnant-like particles inhibit the basal nitric oxide pathway in porcine coronary artery and aortic endothelial cells
Authors: GOULTER Andrew B. , AVELLA Michael , BOTHAM Kathleen M. , ELLIOTT Jonathan
Published: September 2003

The effects of chylomicron remnants on the activity of basally produced nitric oxide (NO) from porcine coronary artery rings and porcine aortic endothelial cells were studied by investigating the effects of chylomicron-remnant-like particles (CMR-LPs) containing porcine apolipoprotein E on the vessel tone of porcine coronary arteries and on cGMP release by aortic endothelial cells. CMR-LPs were oxidized by incubation with CuSO4 (10 μM) for 18 h at 37 °C. Nω-nitro-L-arginine (L-NOARG) and oxidized CMR-LPs (oxCMR-LPs), but not native CMR-LPs, increased the vessel tone of static porcine coronary artery rings (increase in tone as a percentage of the tone induced by depolarizing Krebs–;Henseleit solution: L-NOARG, 14.24±2.09; oxCMR-LPs, 4.98±0.88; and native CMR-LPs, 0.47±0.21). L-NOARG, endothelium removal and oxCMR-LPs also all significantly increased the maximum relaxation of the vessels to S-nitroso-N-acetyl-DL-penicillamine. In addition, oxCMR-LPs reduced the amounts of cGMP released by porcine aortic endothelial cells into the culture medium from 116±12.0 to 84.2±11.6 fmol/μg of cellular protein, mimicking the effects of L-NOARG. These results indicate that oxCMR-LPs, but not native CMR-LPs, inhibit the activity, production or release of NO from unstimulated porcine coronary and aortic endothelial cells. oxCMR-LPs mimicked the addition of L-NOARG and endothelium removal in these experimental systems, suggesting that the lipoproteins were interfering with the L-arginine/NO pathway. This study provides further evidence to support a role of chylomicron remnants in the development of atherosclerosis.
Modulation of the natriuretic peptide system in heart failure: from bench to bedside?
Authors: SCHMITT Matthias , COCKCROFT John R. , FRENNEAUX Michael P.
Published: September 2003

Since the discovery of atrial natriuretic peptide, the unravelling of the natriuretic peptide system has been a story of scientific success. However, bridging the gap between bench and bedside has proved difficult, and as yet has not provided any major clinical progress. In this review we will first give a detailed outline of the key elements constituting the natriuretic peptide system. Secondly, we will briefly explain the underlying rationale, basic concepts and evidence behind currently pursued strategies to potentiate the natriuretic peptide system. Thirdly, we will highlight some of the problems that have so far hindered successful translation of these theoretically viable treatment options into tangible clinical progress.
Terminal vessel hyperperfusion despite organ hypoperfusion in familial dysautonomia
Authors: STEMPER Brigitte , AXELROD Felicia B. , MARTHOL Harald , BROWN Clive , BRYS Miroslav , WELSCH Goetz , HILZ Max J.
Published: September 2003

Patients with familial dysautonomia (FD) exhibit orthostatic hypotension as well as recumbent hypertension. In addition, during dysautonomic crises, patients have hypertensive blood pressure that is presumed to be secondary to episodic vasoconstriction, as well as swollen hands that are presumed to be secondary to vasodilatation. This discrepancy in vascular control is poorly understood, yet may provide insight into the pathophysiology of autonomic crises. To evaluate the pathological mechanisms of overall blood flow and end-organ perfusion, we assessed resting and post-ischaemic limb and skin blood flow in FD patients. In groups of 15 FD patients and 15 controls, we measured resting and post-ischaemic forearm blood flow using venous occlusion plethysmography, and superficial skin blood flow using laser Doppler flowmetry. At rest, arterial inflow was averaged from eight venous occlusion measurements and expressed as percentage volume change/min. Post-ischaemic plethysmographic inflow was determined from the peak influx during the first venous occlusion following 3 min of ischaemia. Transcutaneous forearm partial pressures of oxygen and carbon dioxide were monitored continuously. At rest, plethysmographic limb perfusion was lower in FD patients than in controls, while skin blood flow did not differ between the two groups. After ischaemia, hyperperfusion of the forearm and hand was less pronounced in FD patients than in controls, while skin blood flow was significantly higher in patients than in controls. Partial pressures of O2 and CO2 did not differ between the two groups. We conclude that the reduced overall limb perfusion in patients with FD is due to hypertension-induced structural changes to vessel walls, with an increase in resistance vessel rigidity. The exaggerated post-ischaemic skin perfusion in FD patients seems to be due to deficient sympathetic innervation of precapillary vessels and arteriovenous shunts and to denervation hypersensitivity of intradermal small nerve fibres. Both the reduced limb perfusion and the dysfunctional end-organ blood supply in FD patients are likely to be major contributors to the vasomotor instability observed in these subjects, particularly during periods of stress.
Effects of two lipid-lowering, carotenoid-controlled diets on the oxidative modification of low-density lipoproteins in free-living humans
Authors: AHUJA Kiran D. K. , ASHTON Emma L. , BALL Madeleine J.
Published: September 2003

This study compares the effects of two lipid-lowering diets [a diet enriched in MUFAs (monounsaturated fatty acids) and a HCLF (high-carbohydrate/low-fat) diet] with a controlled carotenoid content on risk factors for coronary heart disease, including in vitro copper-induced LDL (low-density lipoprotein) oxidation and serum lipid levels. A randomized crossover dietary intervention study, with two diets each consumed for 14–16 days, was conducted in 18 women and 13 men aged 20–70 years, recruited via personal contacts and advertisements in newspapers. Both diets (MUFA-enriched diet and HCLF diet) contained the same basic foods and had a controlled carotenoid content, high in lycopene. The in vitro copper-induced oxidation of isolated LDL showed a longer lag phase (mean difference 7.4 min in women and 7.34 min in men) after the MUFA-enriched diet compared with the HCLF diet. Serum total cholesterol, LDL cholesterol and carotenoid levels were similar after the two diets. Serum triacylglycerol levels were significantly lower and those of HDL (high-density lipoprotein) cholesterol were significantly higher at the end of the MUFA-enriched diet compared with the HCLF diet. It is concluded that the significantly longer lag phase for oxidation of LDL, the higher HDL cholesterol level and the lower triacylglycerol level in subjects following a carotenoid-controlled, MUFA-enriched diet may decrease the risk of coronary heart disease.
N-Acetylcysteine improves the disturbed thiol redox balance after methionine loading
Authors: RAIJMAKERS Maarten T. M. , SCHILDERS Geurt W. , ROES Eva Maria , VAN TITS Lambertus J. H. , HAK-LEMMERS Heidy L. M. , STEEGERS Eric A. P. , PETERS Wilbert H. M.
Published: September 2003

Methionine loading seems to be accompanied by increased oxidative stress and damage. However, it is not known how this oxidative stress is generated. We performed the present crossover study to further elucidate the effects of methionine loading on oxidative stress in the blood of healthy volunteers, and to examine possible preventative effects of N-acetylcysteine (NAC) administration. A total of 18 healthy subjects were given two oral methionine loads of 100 mg/kg body weight, 4 weeks apart, one without NAC (Met group), and one in combination with supplementation with 2×900 mg doses of NAC (Met+NAC group). Blood samples were collected before and 2, 4, 8 and 24 h after methionine loading for measurements of thiol levels, protein carbonyls, lipid peroxidation, cellular fibronectin and ferric reducing ability of plasma (FRAP; i.e. antioxidant capacity). After methionine loading, whole-blood levels of free and oxidized cysteine and homocysteine were increased in both groups. Furthermore, the total plasma levels of homocysteine were higher, whereas those of cysteine were lower, after methionine loading in both groups. Lower levels of oxidized homocysteine and a higher free/oxidized ratio were found in the Met+NAC group compared with the Met group. Although the antioxidant capacity decreased after methionine loading, no major changes over time were found for protein carbonyls or cellular fibronectin in either group. Our results suggest that methionine loading may initiate the generation of reactive oxygen species by the (auto)-oxidation of homocysteine. In addition, supplementation with NAC seems to be able to partially prevent excessive increases in the levels of homocysteine in plasma and of oxidized homocysteine in whole blood, and might thereby contribute to the prevention of oxidative stress.
Haemodynamic response to peripheral venous congestion in patients with unexplained recurrent syncope
Authors: BELLARD Elisabeth , FORTRAT Jacques-Olivier , DUPUIS Jean-Marc , VICTOR Jacques , LEFTHÉRIOTIS Georges
Published: September 2003

In patients with recurrent unexplained syncope, exaggerated peripheral venous pooling and impaired circulatory adjustment is thought to contribute to the outcome of a head-up tilt (HUT) test. The present study investigated the role of leg volume changes during venous congestion in the haemodynamic response of patients with recurrent unexplained syncope and the ability to predict the outcome of a HUT test. Changes in calf volume (strain gauge plethysmography), heart rate and arterial blood pressure were recorded in 60 patients with history of unexplained syncope (without postural tachycardia symptom) during venous congestion provoked by pneumatic thigh cuffs while supine at rest and during the initial 10 min of a 45 min 70° HUT test. Twenty-seven patients [age (mean±S.D.), 39±16 years] exhibited symptoms [HUT(+)] and 33 patients (45±14 years) were asymptomatic [HUT(-)]. During venous congestion, mean±S.E.M. calf volume increased in both groups [HUT(-), 4.5±0.2; HUT(+), 4.8±0.4 ml·100 ml-1, not significant), but significantly less during head-upright tilt [HUT(-), 3.3±0.2, P<0.01; HUT(+), 2.6±0.3 ml·100 ml-1, P<0.001] without differences between the groups. During venous congestion, arterial pressure increased significantly in asymptomatic HUT(-) patients, but not in the HUT(+) patients. Calf volume changes did not correlate with a symptomatic outcome to a 70° HUT. The lack of exaggerated venous pooling during venous congestion and the inability of calf volume changes to predict a positive HUT suggest that excessive venous pooling does not contribute to the outcome of HUT. Attenuated changes in arterial pressure during venous congestion while supine suggest impaired adjustment of peripheral resistance to leg venous occlusion.
Cardiac function during mental stress: cholinergic modulation with pyridostigmine in healthy subjects
Authors: SANT'ANNA Isis Délio , DE SOUSA Eduardo Branco , DE MORAES Alvaro Villela , LOURES Débora Lopes , MESQUITA Evandro Tinoco , DA NÓBREGA Antonio Claudio Lucas
Published: September 2003

Mentally or emotionally stressful situations occur throughout our lives and cause physiological haemodynamic responses. In patients with coronary artery disease, such events can also induce myocardial ischaemia and ventricular arrhythmias, increasing mortality rates. The purpose of the present study was to determine the acute effects of the oral administration of pyridostigmine, a reversible cholinesterase inhibitor and thus an indirect cholinomimetic drug, on echocardiographic variables during mental stress in healthy subjects. A total of 18 healthy young volunteers were subjected to mental stress tests (mental arithmetic and the Stroop colour–word test) 2 h after the oral administration of either placebo or pyridostigmine bromide (45 mg), using a balanced-randomized, double-blind, crossover protocol. During mental stress, heart rate (pyridostigmine, 64±1 beats/min; placebo, 70±1 beats/min; P=0.0003) and diastolic blood pressure (pyridostigmine, 66±2 mmHg; placebo, 79±3 mmHg; P=0.01) were lower in the pyridostigmine group, but systolic pressure was not (pyridostigmine, 124±3 mmHg; placebo, 123±3 mmHg; P=0.40). There were no detectable abnormalities in the left ventricular wall motion score during mental stress, but left ventricular outflow tract mean velocity (pyridostigmine, 0.68±0.02 m/s; placebo, 0.64±0.02 m/s; P<0.05) and mitral inflow velocity deceleration (placebo, 4.05±0.18 m/s2; pyridostigmine, 4.41±0.16 m/s2; P<0.05) were higher in the pyridostigmine group. In conclusion, cholinergic stimulation with pyridostigmine seems to increase left ventricular diastolic function during mental stress in healthy subjects.