Genome-wide CRISPR screen reveals CLPTM1L as a lipid scramblase required for efficient glycosylphosphatidylinositol biosynthesis.

SignificanceScramblases translocate lipids across the lipid bilayer without consumption of ATP, thereby regulating lipid distributions in cellular membranes. Cytosol-to-lumen translocation across the endoplasmic reticulum (ER) membrane is a common process among lipid glycoconjugates involved in posttranslational protein modifications in eukaryotes. These translocations are thought to be mediated by specific ER-resident scramblases, but the identity of these proteins and the underlying molecular mechanisms have been elusive. Here, we show that CLPTM1L, an integral membrane protein with eight putative transmembrane domains, is the major lipid scramblase involved in efficient glycosylphosphatidylinositol biosynthesis in the ER membrane. Our results validate the long-standing hypothesis that lipid scramblases ensure the efficient translocations of lipid glycoconjugates across the ER membrane for protein glycosylation pathways.

Osteoprotegerin in Cardiometabolic Disorders.

Osteoprotegerin (OPG), a glycoprotein traditionally implicated in bone remodelling, has been recently related to cardiovascular disease (CVD). Human studies show a positive relationship between circulating OPG, vascular damage, and CVD, and as such OPG has emerged as a potential biomarker for CVD. This review focuses on the relationship between circulating OPG and different endocrine cardiometabolic alterations such as type 1 and 2 diabetes. The association of OPG with diabetic complications (neuropathy, nephropathy, or retinopathy) as well as with atherosclerosis, coronary artery calcification, morbidity, and mortality is pointed out. Moreover, OPG modulation by different treatments is also established. Besides, other associated diseases such as obesity, hypertension, and metabolic syndrome, which are known cardiovascular risk factors, are also considered.

Influence of pre-analytical and analytical factors on osteoprotegerin measurements.

INTRODUCTION: Osteoprotegerin (OPG), an osteoclastogenesis inhibitor implicated in bone remodelling, has emerged as a potential biomarker for cardiovascular disease. In order to implement OPG determination in the clinical laboratory, it is crucial to identify the most appropriate specimen type, preparation and measurement conditions. The present study focuses on identifying the pre-analytical variables that may influence OPG measurements. METHODS: Serum and plasma (in EDTA, heparin and citrate) were collected from 45 healthy volunteers (men (n=21, 46.7%), women (n=24, 53.3%)). OPG was analysed by ELISA. The influence of the centrifugation speed, the number of freeze-thaw cycles, delay in sample processing, thermo-stability and endogenous interfering agents (haemolysis, triglycerides, bilirubin, cholesterol and RANKL) were studied. RESULTS: OPG concentrations were significantly lower (p<0.0001) in serum (1015±357 pg/mL) than in all plasma samples (1314±448 pg/mL in EDTA, 1209±417 pg/mL in heparin and 1260±498 pg/mL in citrate). Increasing centrifugation speed (200 g to 3000 g) did not change serum OPG concentration (p=0.88). However, OPG concentration significantly increased when centrifuged serum samples were stored at 48 h at room temperature (p<0.0001). Repeated freeze-thaw cycles did not modify OPG levels until 4 cycles (p<0.0001). Increasing time before processing the samples (2 h and 6 h) raised OPG concentrations both at room temperature (p<0.0001) or 4°C (p<0.001). Positive concentration-dependent interference of triglycerides was found in the analysed pooled samples; however, OPG concentrations were falsely diminished with haemoglobin interference. Bilirubin, cholesterol and RANKL did not interfere with OPG measurements.

Correlation between serum content of the main COPs (cholesterol oxidation products) from autoxidation and cardiovascular risk factors.

BACKGROUND/AIMS: Risk factors for cardiovascular disease (CVD) have been proven to be associated with an increased oxidative stress. Several studies have considered cholesterol oxidation products (COPs) as specific in vivo markers of oxidative stress. The aim of this study was to investigate the association between the levels of COPs derived from autoxidation processes and established cardiovascular risk factors, comparing the levels of serum COPs in subjects with or without showing values out of the reference ranges. METHODS: It was a cross-sectional study in which 88 subjects were recruited and individual and total COPs from autoxidation origin was analyzed in serum by GC-MS. The simultaneous correlation of COPs with different CVD risk factors have been analyzed. RESULTS AND DISCUSSION: A great variability of total COPs concentrations were found. Subjects presented total COPs values from 0.091 to 2.052 µg/mL. Total COPs were significantly higher (p < 0.05) in patients with hypertriglycerolemia, hypertension, diabetes and overweight/ obesity status compared to those subjects who did not present those CVD risk factors. Moreover, 7α and 7ß hydroxycholesterol and 7-ketocholesterol were significantly higher (p < 0.05) in patients with hypertension and diabetes. No significant differences in total COPs were found between patients with and without hypercholesterolemia. CONCLUSIONS: The obtained results showed that the analyzed COPs correlate well with at least 4 out of 6 risk factors of development of CVD.

Correlation between serum content of the main COPs (cholesterol oxidationproducts) from autoxidation and cardiovascular risk factors / Correlación entre los productos de oxidación de colesterol (COPs) formados por autooxidación y factores de riesgo cardiovascular

Background/aims: Risk factors for cardiovascular disease (CVD) have been proven to be associated with an increased oxidative stress. Several studies have considered cholesterol oxidation products (COPs) as specific in vivo markers of oxidative stress. The aim of this study was to investigate the association between the levels of COPs derived from autoxidation processes and established cardiovascular risk factors, comparing the levels of serum COPs in subjects with or without showing values out of the reference ranges. Methods: It was a cross-sectional study in which 88 subjects were recruited and individual and total COPs from autoxidation origin was analyzed in serum by GC-MS. The simultaneous correlation of COPs with different CVD risk factors have been analyzed. Results and discussion: A great variability of total COPs concentrations were found. Subjects presented total COPs values from 0.091 to 2.052 μg/mL. Total COPs were significantly higher (p < 0.05) in patients with hyper-triglycerolemia, hypertension, diabetes and overweight/ obesity status compared to those subjects who did not present those CVD risk factors. Moreover, 7α and 7β hydroxycholesterol and 7-ketocholesterol were significantly higher (p < 0.05) in patients with hypertension and diabetes. No significant differences in total COPs were found between patients with and without hypercholes-terolemia. Conclusions: The obtained results showed that the analyzed COPs correlate well with at least 4 out of 6 risk factors of development of CVD (AU)

Introducción: Se ha demostrado que los factores de riesgo cardiovascular están estrechamente asociados con un elevado nivel de estrés oxidativo. Varios estudios consideran a los productos de oxidación del colesterol (COPs) como marcadores específicos in vivo de estrés oxidativo. El objetivo de este trabajo fue estudiar la asociación entre los niveles de COPs derivados de procesos de autooxidación de colesterol y factores de riesgo cardiovascular, comparando el contenido sérico de COPs en sujetos afectados o no por dichos factores. Métodos: Se trata de un estudio transversal en el que se reclutaron 88 personas a las que se analizó el perfil de óxidos de colesterol en suero procedentes de autooxidación, por cromatografía de gases-espectrometría de masas. Se valoró la correlación de los niveles de COPs con diferentes factores de riesgo cardiovascular. Resultados y discusión: Se encontró una gran variabilidad en el contenido en COPs totales, observándose valores entre 0,091 y 2,052 μg/mL. COPs totales fueron significativamente superiores (p < 0,05) en pacientes con hipertrigliceridemia, hipertensión, diabetes y sobrepeso/ obesidad con respecto a aquellos sujetos que no presentaron estos factores de riesgo cardiovascular. Además, 7α y 7β-hidroxicolesterol y 7-ketocolesterol mostraron valores mayores (p < 0,05) en pacientes con hipertensión y diabetes. No se observaron diferencias en COPs totales entre pacientes con y sin hipercolesterolemia. Conclusiones: Los resultados de este estudio mostraron que los COPs analizados presentan altos niveles de correlación con, al menos, 4 de 6 factores de riesgo cardiovascular considerados (AU)

Adiponectin diminishes platelet aggregation and sCD40L release. Potential role in the metabolic syndrome.

The proinflammatory and proatherogenic mediator, soluble CD40 ligand (CD40L), is increased in the metabolic syndrome (MS) and released from platelets. We hypothesized that adiponectin modulates platelet function, and we sought to evaluate the association of adiponectin and sCD40L levels with platelet aggregation in MS and the effects of adiponectin on platelet aggregation and activation. Platelet aggregation and circulating adiponectin, sCD40L and P-selectin were determined in 30 controls and 30 patients with MS. Also, in vitro studies were performed in platelet-rich plasma from nine healthy volunteers. Adiponectin receptors were demonstrated by Western blotting and flow cytometry. ADP and epinephrine platelet aggregation was measured after preincubation with adiponectin. sCD40L and P-selectin secretion was measured in the supernatants by ELISA. Patients with MS had higher sCD40L and P-selectin than controls (5.96 +/- 0.50 vs. 4.28 +/- 0.41 ng/ml, P < 0.05, and 151 +/- 8 vs. 122 +/- 9 ng/ml, P < 0.05). By contrast, adiponectin was lower in patients with MS than in controls (5.25 +/- 0.30 vs. 7.35 +/- 0.34 microg/ml, P < 0.001). Higher platelet aggregation was found in MS. Adiponectin inversely correlated with P-selectin (R = -0.35, P = 0.009), sCD40L (r = -0.24, P = 0.05) and epinephrine and collagen induced aggregation (r = -0.80, P = 0.005; r = -0.70, P = 0.011). Platelets express the receptors for adiponectin. Platelet aggregatory response to epinephrine and ADP significantly decreased following preincubation with adiponectin (96 +/- 4 vs. 23 +/- 3%, P < 0.001, and 102 +/- 9 vs. 85 +/- 9%, P = 0.004). Adiponectin prevented platelet sCD40L release (1.63 +/- 0.15 vs. 2.04 +/- 0.20 ng/ml, P < 0.001). Enhanced platelet aggregation and activation markers are found in MS associated with low adiponectin concentrations. Novel evidence is provided demonstrating that adiponectin has antithrombotic properties, since it inhibits platelet aggregation and platelet activation.

Advantage of salivary cortisol measurements in the diagnosis of glucocorticoid related disorders.

OBJECTIVE: Salivary cortisol in the assessment of glucocorticoid related disorders. DESIGN-METHODS: Serum and salivary cortisol were measured in 189 patients (22 Cushing's syndrome, 67 pseudo-Cushing, 11 Addison's disease, 89 controls) at 8:00 and 24:00 h. RESULTS: Serum and salivary cortisol correlated in the whole study population (r=0.62, p=0.000). Morning serum and saliva cortisol in Addison's disease were lower than in controls (6.74+/-1.69 vs 22.58+/-1.78 microg/dL, and 0.15+/-0.25 vs 0.67+/-0.12 microg/dL) (p<0.001). Morning serum cortisol was similar in controls and patients with Cushing's syndrome or pseudo-Cushing (22.58+/-1.78 vs 13.96+/-6.02 vs 16.13+/-1.69 microg/dL). Morning serum and salivary cortisol at 8:00 had the same sensitivity to distinguish patients with Addison's disease from healthy controls. 24:00 am serum cortisol in controls (2.61+/-0.20 microg/dL) was lower than in the pseudo-Cushing group (6.53+/-0.77 microg/dL, p<0.001) and in Cushing's syndrome (10.90+/-2.36 microg/dL, p=0.003). 24:00 am salivary cortisol in controls (0.0025+/-0.001 microg/dL) was lower than in patients with Cushing's syndrome (0.58+/-0.11 microg/dL, p<0.001) and those higher than in patient with pseudo-Cushing (0.10+/-0.06 microg/dL, p=0.001). Both salivary cortisol and serum cortisol presented high specificity (82% and 100%) to detect Cushing's syndrome but salivary cortisol higher sensitivity (saliva 88% and serum 50%). CONCLUSION: Morning salivary cortisol is as good as serum as screening test for patients with Addison's disease and nighttime salivary cortisol is more adequate than serum in the screening of Cushing's syndrome.

Soluble CD40L and cardiovascular risk in women.

BACKGROUND: The immune-signaling dyad CD40/CD40L promotes atherogenesis, and patients with unstable angina have elevated plasma levels of soluble CD40L (sCD40L) and membrane-bound CD40L. It is unknown, however, whether elevations of circulating sCD40L precede the onset of acute cardiovascular symptoms. METHODS AND RESULTS: In a prospective, nested case-control evaluation of healthy middle-aged women, mean concentrations of sCD40L at baseline were significantly higher among 130 participants who subsequently developed myocardial infarction, stroke, or cardiovascular death (cases), compared with 130 age- and smoking-matched women who remained free of cardiovascular disease (controls) during a 4-year follow-up (2.86 ng/mL for cases versus 2.09 ng/mL for controls; P=0.02). Women with concentrations above the 95th percentile of the control distribution (>3.71 ng/mL) had a significantly increased relative risk (RR) of developing future cardiovascular events (RR, 3.3; 95% CI, 1.2 to 8.6; P=0.01) that remained after adjustment for usual cardiovascular risk factors (multivariate RR, 2.8; 95% CI, 0.9 to 8.0; P=0.05). CONCLUSIONS: High plasma concentrations of sCD40L may be associated with increased vascular risk in apparently healthy women.

Biochemical assessment of myocardial fibrosis in hypertensive heart disease.

Fibrous tissue accumulation is an integral feature of the adverse structural remodeling of cardiac tissue seen with hypertensive heart disease. Given the importance of fibrous tissue in leading to myocardial dysfunction and failure, noninvasive monitoring of myocardial fibrosis by use of serological markers of collagen turnover could prove a clinically useful tool, particularly given the potential for cardioprotective and cardioreparative pharmacological strategies. An emerging experimental and clinical experience holds promise for the use of radioimmunoassays of various serological markers of fibrillar collagen type I and type III turnover in arterial hypertension. More specifically, the measurement of serum concentrations of procollagen type I C-terminal propeptide (a peptide that is cleaved from procollagen type I during the synthesis of fibril-forming collagen type I) may provide indirect diagnostic information on both the extent of myocardial fibrosis and the ability of antihypertensive treatment to diminish collagen type I synthesis and reduce myocardial fibrosis. This approach represents an exciting and innovative strategy, and available data set the stage for larger trials, in which noninvasive measures of fibrosis in hypertensive heart disease could prove useful.

Usefulness of serum carboxy-terminal propeptide of procollagen type I in assessment of the cardioreparative ability of antihypertensive treatment in hypertensive patients.

BACKGROUND: We investigated whether serum concentration of carboxy-terminal propeptide of procollagen type I (PIP), a marker of collagen type I synthesis, can be used to assess the ability of antihypertensive treatment to regress myocardial fibrosis in hypertensive patients. METHODS AND RESULTS: The study was performed in 37 patients with essential hypertension and hypertensive heart disease. After randomization, 21 patients were assigned to losartan and 16 patients to amlodipine treatment. At baseline and after 12 months, right septal endomyocardial biopsies were performed to quantify collagen volume fraction (CVF) on picrosirius red-stained sections with an automated image-analysis system. Serum PIP was measured by specific radioimmunoassay. Nineteen patients in the losartan group and 11 in the amlodipine group finished the study. Time-course changes in blood pressure during treatment were similar in the 2 groups of patients. In losartan-treated patients, CVF decreased from 5.65+/-2.03% to 3.96+/-1.46% (P<0.01) and PIP from 127+/-30 to 99+/-26 microgram/L (P<0.01). Neither CVF or PIP changed significantly in amlodipine-treated patients. CVF was directly correlated with PIP (r=0.44, P<0.001) in all hypertensives before and after treatment. CONCLUSIONS: These findings suggest that the ability of antihypertensive treatment to regress fibrosis in hypertensives with biopsy-proven myocardial fibrosis is independent of its antihypertensive efficacy. Our data also suggest that blockade of the angiotensin II type 1 receptor is associated with inhibition of collagen type I synthesis and regression of myocardial fibrosis in hypertensives. Thus, determination of serum PIP may be useful to assess the cardioreparative properties of antihypertensive treatment in hypertensives.

Characterisation with stable isotopes of the presence of a lag phase in the gastric emptying of liquids.

BACKGROUND: Gastric emptying of non-nutrient liquids usually lacks the presence of an initial delay phase (lag phase), and so it has been considered to be monoexponential with an initial rapid phase followed by a slower emptying phase. However a lag phase in the gastric emptying of liquids can be found if there is a high caloric density in the liquid meal. AIM OF THE STUDY: To characterise with stable isotopes the presence of a lag phase in the gastric emptying of non-solid meals. METHODS: Healthy volunteers ingested a low caloric liquid meal (345 KJ/ 200 mL) (LCLM), a high caloric liquid meal (1135 KJ/180 mL) (HCLM) or a semisolid meal (1403 KJ/500 mL) (SSM). Test meals were labelled with 13C-acetate. Breath samples were collected for 13CO2 measurement and data were fitted to a power exponential function. RESULTS: Non-solid meals can have different behaviour related to the initial emptying. The presence of a lag phase in the gastric emptying of liquids was not masked by the processing of the tracer previous to its detection in breath. While the LCLM and SSM showed a rapid initial emptying phase (no lag phase), the HCLM has an initial slow emptying phase. The slower gastric emptying of the HCLM compared to the SSM was related to the presence of a lag phase in the gastric emptying of the HCLM. CONCLUSIONS: The 13C-acetate breath test is very accurate to identify and study the lag phase if present of liquid meals.

Transforming growth factor beta in hypertensives with cardiorenal damage.

We investigated whether a relationship exists between circulating transforming growth factor beta -1 (TGF-beta(1)), collagen type I metabolism, microalbuminuria, and left ventricular hypertrophy in essential hypertension and whether the ability of the angiotensin II type 1 receptor antagonist losartan to correct microalbuminuria and regress left ventricular hypertrophy in hypertensives is related to changes in TGF-beta(1) and collagen type I metabolism. The study was performed in 30 normotensive healthy controls and 30 patients with never-treated essential hypertension classified into 2 groups: those with microalbuminuria (urinary albumin excretion >30 and <300 mg/24 h) associated with left ventricular hypertrophy (left ventricular mass index >116 g/m(2) for men and >104 g/m(2) for women) (group B; n=17) and those without microalbuminuria or left ventricular hypertrophy (group A; n=13). The measurements were repeated in all patients after 6 months of treatment with losartan (50 mg once daily). The serum concentration of TGF-beta(1) was measured by a 2-site ELISA method, and the serum concentrations of carboxy-terminal propeptide of procollagen type I (a marker of collagen type I synthesis) and carboxy-terminal telopeptide of collagen type I (a marker of collagen type I degradation) were measured by specific radioimmunoassays. The duration of hypertension and baseline values of blood pressure were similar in the 2 groups of patients. No differences in serum TGF-beta(1), carboxy-terminal propeptide of procollagen type I, and carboxy-terminal telopeptide of collagen type I were found between normotensives and group A of hypertensives. Serum TGF-beta(1), carboxy-terminal propeptide of procollagen type I, and the ratio of carboxy-terminal propeptide of procollagen type I to carboxy-terminal telopeptide of collagen type I were increased (P<0.05) in group B of hypertensives compared with group A of hypertensives and normotensives. No differences in carboxy-terminal telopeptide of collagen type I were found among the 3 groups of subjects. After treatment with losartan, microalbuminuria and left ventricular hypertrophy persisted in 6 patients (then considered nonresponders) and disappeared in 11 patients (then considered responders) from group B. Compared with nonresponders, responders exhibited similar control of blood pressure and higher (P<0.05) blockade of angiotensin II type 1 receptors (as assessed by a higher increase in plasma levels of angiotensin II). Whereas TGF-beta(1), carboxy-terminal propeptide of procollagen type I, and the ratio of carboxy-terminal propeptide of procollagen type I to carboxy-terminal telopeptide of collagen type I decreased (P<0.05) in responders, no changes in these parameters were observed in nonresponders. These findings show that an association exists between an excess of TGF-beta(1), stimulation of collagen type I synthesis, inhibition of collagen type I degradation, and cardiorenal damage in a group of patients with essential hypertension. In addition, our results suggest that the ability of losartan to blunt the synthesis of TGF-beta(1) and normalize collagen type I metabolism may contribute to protect the heart and the kidney in a fraction of patients with essential hypertension.

[Biochemical diagnosis of hypertensive myocardial fibrosis]. / Diagnóstico bioquímico de la fibrosis miocárdica hipertensiva.

A substantial increase in fibrillar collagen has been observed in the left cardiac ventricle of animals and humans with arterial hypertension. Hypertensive myocardial fibrosis is the result of both increased collagen types I and III due to the fact that its synthesis by fibroblasts and myofibroblasts is stimulated and its extracellular collagen degradation unchanged or decreased extracellular collagen degradation. Hemodynamic and non-hemodynamic factors may be involved in the disequilibrium between collagen synthesis and degradation that occurs in hypertension. As shown experimentally and clinically, an exaggerated rise in fibrillar collagen content promotes abnormalities of cardiac function, contributes to the decrease in coronary reserve and facilitates alterations in the electrical activity of the left ventricle. Although microscopic examination of cardiac biopsies is the most reliable method for documenting and measuring myocardial fibrosis, the development of non-invasive methods to indicate the presence of myocardial fibrosis in hypertensive patients would be useful. We have therefore applied a biochemical method based on the measurement of serum peptides derived from the tissue formation when synthesized and degradation of fibrillar collagens to monitor the turnover of these molecules in rats with spontaneous hypertension and patients with essential hypertension.

Chronic AT(1) blockade stimulates extracellular collagen type I degradation and reverses myocardial fibrosis in spontaneously hypertensive rats.

It has been suggested that left ventricular fibrosis in spontaneously hypertensive rats (SHR) is the result of both exaggerated collagen synthesis and insufficient collagen degradation. We have shown previously that chronic treatment with the angiotensin II type 1 receptor antagonist losartan results in diminished synthesis of collagen type I molecules and reversal of myocardial fibrosis in SHR. This study was designed to investigate whether losartan also affects the extracellular degradation of collagen type I fibers in the left ventricle of SHR. The study was performed in 30-week-old normotensive Wistar-Kyoto rats (WKY), untreated SHR, and SHR treated with orally administered losartan (20 mg/kg per day) for 14 weeks before they were killed. Ventricular collagenase activity was determined by degradation of [(14)C]collagen with tissue extracts. Ventricular expression of tissue inhibitor of metalloproteinases 1 (TIMP-1) mRNA was analyzed by Northern blot. A histomorphometric study of the left ventricle was performed in all rats. Compared with WKY, SHR exhibited left ventricular hypertrophy, increased (P<0.05) blood pressure, left ventricular collagen volume fraction and TIMP-1 mRNA, and diminished (P<0.05) collagenase activity. After the treatment period, blood pressure was higher (P<0.05) in losartan-treated SHR than in WKY, and no significant differences were noted in the remaining parameters between the 2 strains of rats. Compared with untreated SHR, treated SHR showed no left ventricular hypertrophy, diminished (P<0.05) blood pressure, left ventricular collagen volume fraction and TIMP-1 mRNA, and increased (P<0.05) collagenase activity. These results suggest that the transcription of the TIMP-1 gene is upregulated in the hypertrophied and fibrotic left ventricle of adult SHR. Upregulation of TIMP-1 may account for diminished collagenase activity in the myocardium of those rats. Chronic angiotensin II type 1 receptor blockade with losartan resulted in inhibition of TIMP-1 expression and stimulation of collagenase activity in the left ventricle of SHR. It is proposed that angiotensin II may facilitate myocardial fibrosis in SHR by depressing the collagenase-mediated extracellular degradation of collagen fibers.

Serum carboxy-terminal propeptide of procollagen type I is a marker of myocardial fibrosis in hypertensive heart disease.

BACKGROUND: This study was designed to investigate whether the serum concentration of the carboxy-terminal propeptide of procollagen type I (PIP), a marker of collagen type I synthesis, is related to myocardial fibrosis in hypertensive patients. METHODS AND RESULTS: The study was performed in 26 patients with essential hypertension in which ischemic cardiomyopathy was excluded after a complete medical workup. Right septal endomyocardial biopsies were performed in hypertensive patients to quantify collagen content. Collagen volume fraction (CVF) was determined on picrosirius red-stained sections with an automated image analysis system. The serum concentration of PIP was measured by specific radioimmunoassay. Compared with normotensives, both serum PIP and CVF were increased (P<0.001) in hypertensives. A direct correlation was found between CVF and serum PIP (r=0.471, P<0.02) in all hypertensives. Histological analysis revealed the presence of 2 subgroups of patients: 8 with severe fibrosis and 18 with nonsevere fibrosis. Serum PIP was higher (P<0.05) in patients with severe fibrosis than in patients with nonsevere fibrosis. Using receiver operating characteristic curves, we observed that a cutoff of 127 microg/L for PIP provided 78% specificity and 75% sensitivity for predicting severe fibrosis with a relative risk of 4.80 (95% CI, 1.19 to 19.30). CONCLUSIONS: These results show a strong correlation between myocardial collagen content and the serum concentration of PIP in essential hypertension. Although preliminary, these findings suggest that the determination of PIP may be an easy and reliable method for the screening and diagnosis of severe myocardial fibrosis associated with arterial hypertension.

Losartan inhibits the post-transcriptional synthesis of collagen type I and reverses left ventricular fibrosis in spontaneously hypertensive rats.

OBJECTIVE: Previous studies have shown that as well as left ventricular hypertrophy, myocardial fibrosis develops early in rats with spontaneous hypertension (SHR). The present study was designed to investigate whether chronic treatment with the angiotensin II type 1 (AT1) receptor antagonist losartan modifies collagen type I metabolism and reverses left ventricular fibrosis in young SHR with left ventricular hypertrophy. DESIGN: The study was performed in 30-week-old normotensive Wistar-Kyoto (WKY) rats, untreated SHR and SHR treated with losartan (20 mg/mg per day, orally) for 14 weeks before they were killed. METHODS: Ventricular pro-alpha 1 (I) collagen messenger RNA was analyzed by Northern blot. Serum levels of the carboxy-terminal propeptide of procollagen type I (PIP) and the pyridoline cross-linked telopeptide domain of collagen type I (CITP) were determined by specific radioimmunoassays as markers of collagen type I synthesis and degradation, respectively. Collagen volume fraction was determined in the left ventricle by quantitative morphometry. RESULTS: Compared with WKY rats, SHR exhibited increased (P < 0.05) mean arterial pressure, pro-alpha 1 (I) collagen messenger RNA, PIP and left ventricular collagen volume fraction, and similar CITP values. After the treatment period, mean arterial pressure was higher (P < 0.05) in losartan-treated SHR than in WKY rats. Compared with untreated SHR, treated SHR showed no left ventricular hypertrophy and diminished (P < 0.05) values of mean arterial pressure, PIP and left ventricular collagen volume fraction. No changes in pro-alpha 1 (I) collagen messenger RNA and CITP values were observed with treatment in SHR. No significant differences in the left ventricular collagen volume fraction were observed between treated SHR with normal blood pressure and treated SHR with abnormally high blood pressure at the end of the treatment period. CONCLUSIONS: These results suggest that chronic AT1 blockade with losartan decreases the post-transcriptional synthesis of fibril-forming collagen type I molecules in young SHR. This effect may be involved in the ability of this drug to reverse left ventricular fibrosis in young rats with genetic hypertension. Apart from its antihypertensive action, other mechanisms may mediate the antifibrotic effect of losartan in this animal model.

Abnormalities of the extracellular degradation of collagen type I in essential hypertension.

BACKGROUND: This study was designed to investigate whether collagen type I degradation is altered in patients with essential hypertension and whether this alteration could be related to disturbances in the serum matrix metalloproteinase pathway of collagen degradation. A second aim of the study was to assess whether some relation exists between serum markers of collagen type I degradation and left ventricular hypertrophy in hypertensive patients. METHODS AND RESULTS: We measured serum concentrations of carboxy-terminal telopeptide of collagen type I (CITP) as a marker of extracellular collagen type I degradation, of total matrix metalloproteinase-1 (MMP-1), or collagenase, of total tissue inhibitor of metalloproteinases 1 (TIMP-1), and of MMP-1/TIMP-1 complex in 37 patients with never-treated essential hypertension and in 23 normotensive control subjects. Serum concentrations of free MMP-1 and free TIMP-1 were calculated by subtracting the values of MMP-1/TIMP-1 complex from the values of total MMP-1 and total TIMP-1, respectively. Measurements were repeated in 26 hypertensive patients after 1 year of treatment with the ACE inhibitor lisinopril. Baseline free MMP-1 was decreased (P<0.001) and baseline free TIMP-1 was increased (P<0.001) in hypertensives compared with normotensives. No significant differences were observed in the baseline values of CITP between the 2 groups of subjects. Hypertensive patients with baseline left ventricular hypertrophy exhibited lower values of free MMP-1 (P<0.01) and CITP (P<0.05) and higher (P<0.001) values of free TIMP-1 than hypertensive patients without baseline left ventricular hypertrophy. Treated patients attained an increase (P<0.001) in free MMP-1 and a decrease (P<0.05) in free TIMP-1. In addition, serum CITP was increased (P<0.05) in treated hypertensives compared with normotensive subjects. CONCLUSIONS: These findings suggest that systemic extracellular degradation of collagen type I is depressed in patients with essential hypertension and can be normalized by treatment with lisinopril. A depressed degradation of collagen type I may facilitate organ fibrosis in hypertensive patients, namely, in those with left ventricular hypertrophy.

[Studying of gastric emptying for solids and liquids by means of using stable isotopes]. / Estudio del vaciamiento gástrico de sólidos y líquidos mediante el empleo de isótopos estables.

The study of gastric emptying is usually performed by scintigraphy. Over the last years alternative non radioactive methods have been developed based on the stable isotopes technology. Such techniques use 13C-octanoic acid to measure gastric emptying of solids and sodium 13C-acetate to measure liquids emptying. The enrichment of 13C in breath air along the time reflects the velocity of gastric emptying. Kinetic parameters can be obtained from this enrichment to quantify gastric emptying. Samples can be obtained outside the processing laboratory. Due to the characteristics of the method, it is adequate and safe to evaluate pathologies related to gastric emptying and the efficiency of the therapy.