Controlled contrast transcranial Doppler and arterial blood gas analysis to quantify shunt through patent foramen ovale.

BACKGROUND AND PURPOSE: A right-to-left shunt can be identified by contrast transcranial Doppler ultrasonography (c-TCD) at rest and/or after a Valsalva maneuver (VM) or by arterial blood gas (ABG) measurement. We assessed the influence of controlled strain pressures and durations during VM on the right-to-left passage of microbubbles, on which depends the shunt classification by c-TCD, and correlated it with the right-to-left shunt evaluation by ABG measurements in stroke patients with patent foramen ovale (PFO). METHODS: We evaluated 40 stroke patients with transesophageal echocardiography-documented PFO. The microbubbles were recorded with TCD at rest and after 4 different VM conditions with controlled duration and target strain pressures (duration in seconds and pressure in cm H2O, respectively): V5-20, V10-20, V5-40, and V10-40. The ABG analysis was performed after pure oxygen breathing in 34 patients, and the shunt was calculated as percentage of cardiac output. RESULTS: Among all VM conditions, V5-40 and V10-40 yielded the greatest median number of microbubbles (84 and 95, respectively; P<0.01). A significantly larger number of microbubbles were detected in V5-40 than in V5-20 (P<0.001) and in V10-40 than in V10-20 (P<0.01). ABG was not sensitive enough to detect a shunt in 31 patients. CONCLUSIONS: The increase of VM expiratory pressure magnifies the number of microbubbles irrespective of the strain duration. Because the right-to-left shunt classification in PFO is based on the number of microbubbles, a controlled VM pressure is advised for a reproducible shunt assessment. The ABG measurement is not sensitive enough for shunt assessment in stroke patients with PFO.

Role of CCR5 genetic polymorphisms in clinical and histological outcomes of hepatitis C

Background: The CCR5 32-base deletion (CCR5D32), which results into the expression of a non-functioning receptor, has been associated with H CV c learance a nd may influence fibrosis progression i n hepatitis C . We a ssessed t he link between C CR5D32 and c linical outcomes o f HCV. Methods: Genomic D NA was isolated and analyzed b y PCR to i dentify C CR5D32 in 1 303 anti-HCV-positive persons (161 clearers and 1142 chronically infected, 1007 with a liver biopsy). Results: Overall, 200 (15.3%) w ere heterozygote a nd 16 (1.2%) homozygote for CCR5D32. H CV c learance (by univariate) was associated with m ale sex (OR 0.633, 9 5% C I 0.428-0.935, P=0.022), HCV acquisition by blood transfusion (OR 0.360, 95% CI 0.175-0.741, P =0.0056), polymorphisms at IL28B rs12979860 ( OR 0.482, 9 5% C I 0.277-0.839, P =0.0098) a nd rs8099917 ( OR 0.291, 95% CI 0.167-0.508, P=0.000014), but not with CCR5D32. However, CCR5D32 was associated with spontaneous HCV clearance when the 482 females only w ere considered, although the number of homozygotes was small (1/427 chronic vs 3/51 clearers) (OR 24.56, 95% C I 12.5-241.4, P =0.006). T he CCR5D32 deletion was not associated with liver grading and staging scores, fibrosis progression rate, or t herapy response. Conclusions: At v ariance w ith a p revious report (Nattermann et a l, 2011), suggesting that a n on-functional CCR5 m ay hamper H CV clearance, C CR5D32 appeared to b e associated with an increased spontaneous eradication in women (but not men). Given the small number of CCR5D32 homozygote persons, these data need further validation.

Genome-wide association study identifies variants associated with progression of liver fibrosis from HCV infection.

Polymorphisms in IL28B were shown to affect clearance of hepatitis C virus (HCV) infection in genome-wide association (GWA) studies. Only a fraction of patients with chronic HCV infection develop liver fibrosis, a process that might also be affected by genetic factors. We performed a 2-stage GWA study of liver fibrosis progression related to HCV infection. We studied well-characterized HCV-infected patients of European descent who underwent liver biopsies before treatment. We defined various liver fibrosis phenotypes on the basis of METAVIR scores, with and without taking the duration of HCV infection into account. Our GWA analyses were conducted on a filtered primary cohort of 1161 patients using 780,650 single nucleotide polymorphisms (SNPs). We genotyped 96 SNPs with P values <5 × 10(-5) from an independent replication cohort of 962 patients. We then assessed the most interesting replicated SNPs using DNA samples collected from 219 patients who participated in separate GWA studies of HCV clearance. In the combined cohort of 2342 HCV-infected patients, the SNPs rs16851720 (in the total sample) and rs4374383 (in patients who received blood transfusions) were associated with fibrosis progression (P(combined) = 8.9 × 10(-9) and 1.1 × 10(-9), respectively). The SNP rs16851720 is located within RNF7, which encodes an antioxidant that protects against apoptosis. The SNP rs4374383, together with another replicated SNP, rs9380516 (P(combined) = 5.4 × 10(-7)), were linked to the functionally related genes MERTK and TULP1, which encode factors involved in phagocytosis of apoptotic cells by macrophages. Our GWA study identified several susceptibility loci for HCV-induced liver fibrosis; these were linked to genes that regulate apoptosis. Apoptotic control might therefore be involved in liver fibrosis.

Transforming growth factor beta 1 production by CD4+ CD25+ regulatory T cells in peripheral blood mononuclear cells from healthy subjects stimulated with Leishmania guyanensis.

Transforming growth factor beta (TGF-beta) has been shown to be a central immunomodulator used by leishmaniae to escape effective mechanisms of protection in human and murine infections with these parasites. However, all the information is derived from studies of established infection, while little is known about TGF-beta production in response to Leishmania stimulation in healthy subjects. In this study, TGF-beta1 production was demonstrated in peripheral blood mononuclear cells from healthy subjects never exposed to leishmaniae in response to live Leishmania guyanensis, and the TGF-beta1-producing cells were described as a distinct subpopulation of CD4(+) CD25(+) regulatory T cells. The suppressive properties of CD4(+) CD25(+) T cells were demonstrated in vitro by their inhibition of production of interleukin 2 (IL-2) and IL-10 by CD4(+) CD25(-) T cells in the presence of either anti-CD3 or L. guyanensis. Although neutralization of TGF-beta1 did not reverse the suppressive activity of CD4(+) CD25(+) T cells activated by anti-CD3, it reversed the suppressive activity of CD4(+) CD25(+) T cells activated by L. guyanensis. Altogether our data demonstrated that TGF-beta1 is involved in the suppressive activity of L. guyanensis-stimulated CD4(+) CD25(+) T cells from healthy controls.

Genetic dissection of sodium and potassium transport along the aldosterone-sensitive distal nephron: Importance in the control of blood pressure and hypertension.

In this review, we discuss genetic evidence supporting Guyton's hypothesis stating that blood pressure control is critically depending on fluid handling by the kidney. The review is focused on the genetic dissection of sodium and potassium transport in the distal nephron and the collecting duct that are the most important sites for the control of sodium and potassium balance by aldosterone and angiotensin II. Thanks to the study of Mendelian forms of hypertension and their corresponding transgenic mouse models, three main classes of diuretic receptors (furosemide, thiazide, amiloride) and the main components of the aldosterone- and angiotensin-dependent signaling pathways were molecularly identified over the past 20years. This will allow to design rational strategies for the treatment of hypertension and for the development of the next generation of diuretics.

Rapid diagnosis of human brucellosis by peripheral-blood PCR assay.

A single-step PCR assay with genus-specific primers for the amplification of a 223-bp region of the sequence encoding a 31-kDa immunogenetic Brucella abortus protein (BCSP31) was used for the rapid diagnosis of human brucellosis. We examined peripheral blood from 47 patients, with a total of 50 cases of brucellosis, and a group of 60 control subjects, composed of patients with febrile syndromes of several etiologies other than brucellosis, asymptomatic subjects seropositive for Brucella antibodies, and healthy subjects. Diagnosis of brucellosis was established in 35 cases (70%) by isolation of Brucella in blood culture and in the other 15 cases (30%) by clinical and serological means. The sensitivity of our PCR assay was 100%, since it correctly identified all 50 cases of brucellosis, regardless of the duration of the disease, the positivity of the blood culture, or the presence of focal forms. The specificity of the test was 98.3%, and the only false-positive result was for a patient who had had brucellosis 2 months before and possibly had a self-limited relapse. In those patients who relapsed, the results of our PCR assay were positive for both the initial infection and the relapse, becoming negative once the relapse treatment was completed and remaining negative in the follow-up tests at 2, 4, and 6 months. In conclusion, these results suggest that the PCR assay is rapid and easy to perform and highly sensitive and specific, and it may therefore be considered a useful tool for diagnosis of human brucellosis.

Strategy for optimizing DNA amplification in a peripheral blood PCR assay used for diagnosis of human brucellosis.

We studied two of the possible factors which can interfere with specific DNA amplification in a peripheral-blood PCR assay used for the diagnosis of human brucellosis. We found that high concentrations of leukocyte DNA and heme compounds inhibit PCR. These inhibitors can be efficiently suppressed by increasing the number of washings to four or five and decreasing the amount of total DNA to 2 to 4 microg, thereby avoiding false-negative results.

Incremental Prognostic Value of Myocardial Blood Flow Quantification with Rb-82 Cardiac PET in Patients With Known or Suspected CAD

Rb-82cardiac PET has been used to non-invasively assess myocardial blood flow (MBF)and myocardial flow reserve (MFR). The impact of MBF and MFR for predictingmajor adverse cardiovascular events (MACE) has not been investigated in aprospective study, which was our aim. MATERIAL AND METHODS: In total, 280patients (65±10y, 36% women) with known or suspected CAD were prospectivelyenrolled. They all underwent both a rest and adenosine stress Rb-82 cardiacPET/CT. Dynamic acquisitions were processed with the FlowQuant 2.1.3 softwareand analyzed semi-quantitatively (SSS, SDS) and quantitatively (MBF, MFR) andreported using the 17-segment AHA model. Patients were stratified based on SDS,stress MBF and MFR and allocated into tertiles. For each group, annualizedevent rates were computed by dividing the number of annualized MACE (cardiacdeath, myocardial infarction, revascularisation or hospitalisation forcardiac-related event) by the sum of individual follow-up periods in years.Outcome were analysed for each group using Kaplan-Meier event-free survivalcurves and compared using the log-rank test. Multivariate analysis wasperformed in a stepwise fashion using Cox proportional hazards regressionmodels (p<0.05 for model inclusion). RESULTS: In a median follow-up of 256days (range 168-440d), 44 MACE were observed. Ischemia (SDS≥2) was observed in95 patients who had higher annualized MACE rate as compared to those without(55% vs. 9.8%, p<0.0001). The group with the lowest MFR tertile (MFR<1.76)had higher MACE rate than the two highest tertiles (51% vs. 9% and 14%,p<0.0001). Similarly, the group with the lowest stress MBF tertile(MBF<1.78mL/min/g) had the highest annualized MACE rate (41% vs. 26% and 6%,p=0.0002). On multivariate analysis, the addition of MFR or stress MBF to SDSsignificantly increased the global χ2 (from 56 to 60, p=0.04; and from56 to 63, p=0.01). The best prognostic power was obtained in a model combiningSDS (p<0.001) and stress MBF (p=0.01). Interestingly, the integration ofstress MBF enhanced risk stratification even in absence of ischemia.CONCLUSIONS: Quantification of MBF or MFR in Rb-82 cardiac PET/CT providesindependent and incremental prognostic information over semi-quantitativeassessment with SDS and is of value for risk stratification.

Modelling the cardiovascular system for automatic interpretation of the blood pressure curve

A four compartment model of the cardiovascular system is developed. To allow for easy interpretation and to minimise the number of parameters, an effort was made to keep the model as simple as possible. A sensitivity analysis is first carried out to determine which are the most important model parameters to characterise the blood pressure signal. A four stage process is then described which accurately determines all parameter values. This process is applied to data from three patients and good agreement is shown in all cases.

Blood pressure and cognitive function: a prospective analysis among adolescents in Seychelles.

OBJECTIVE: An inverse relationship between blood pressure (BP) and cognitive function has been found in adults, but limited data are available in adolescents and young adults. We examined the prospective relation between BP and cognitive function in adolescence. METHODS: We examined the association between BP measured at the ages of 12-15 years in school surveys and cognitive endpoints measured in the Seychelles Child Development Study at ages 17 (n = 407) and 19 (n = 429) years, respectively. We evaluated multiple domains of cognition based on subtests of the Cambridge Neurological Test Automated Battery (CANTAB), the Woodcock Johnson Test of Scholastic Achievement (WJTA), the Finger Tapping test (FT) and the Kaufman Brief Intelligence Test (K-BIT). We used age, sex and height-specific z-scores of SBP, DBP and mean arterial pressure (MAP). RESULTS: Six out of the 21 cognitive endpoints tested were associated with BP. However, none of these associations were found to hold for both males and females or for different subtests within the same neurodevelopmental domain or for both SBP and DBP. Most of these associations disappeared when analyses were adjusted for selected potential confounding factors such as socio-economic status, birth weight, gestational age, BMI, alcohol consumption, blood glucose, and total n-3 and n-6 polyunsaturated fats. CONCLUSIONS: Our findings do not support a consistent association between BP and subsequent performance on tests assessing various cognitive domains in adolescents.

Hyperlactatémie et acidose lactique chez le patient critique [Hyperlactatemia and lactic acidosis in the critically ill patient].

Hyperlactatemia is associated with an ominous prognosis in critical illness and must be rapidly detected. Lactate is produced by glycolysis through reduction of pyruvate, itself oxidized in the mitochondria. It is transported to the liver and converted to glucose through gluconeogenesis (Cori's cycle). Hyperlactatemia can result from excessive production or reduced clearance. Excess production can occur in aerobic conditions, following an increase in pyruvate generation, or in anaerobic conditions, due to impaired pyruvate oxidation. Reduced lactate clearance occurs as a result of liver hypoperfusion or hepatic failure. Lactate/pyruvate ratio, as well as the concomitant existence of metabolic acidosis (lactic acidosis), help distinguish the different mechanisms leading to hyperlactatemia, which are reviewed in detail in this article.

Administration intra-vitréenne de liposomes pour la vectorisation de principes actifs [The use of liposomes as intravitreal drug delivery system].

Liposomes are vesicular lipidic systems allowing encapsulation of drugs. This article reviews the relevant issues in liposome structure (composition and size), and their influence on intravitreal pharmacokinetics. Liposome-mediated drug delivery to the posterior segment of the eye via intravitreal administration has been addressed by several authors and remains experimental. Liposomes have been used for intravitreal delivery of antibiotics, antivirals, antifungal drugs, antimetabolites, and cyclosporin. Encapsulation of these drugs within liposomes markedly increased their intravitreal half-life, and reduced their retinal toxicity. Liposomes have also shown an attractive potential for retinal gene transfer by intravitreal delivery of plasmids or oligonucleotides.

High heritability of ambulatory blood pressure in families of East African descent.

We estimated the heritability of ambulatory systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP) in east African families with at least 2 hypertensive siblings and living in the Seychelles islands (Indian Ocean). The sample consisted of 314 individuals (147 men and 167 women), both normotensive and hypertensive, from 76 pedigrees (mean+/-SD of 4.1+/-2.8 persons per pedigree). After a 2-week off-treatment period, daytime and nighttime ambulatory blood pressure (BP) was monitored. Office BP was measured with a standard mercury sphygmomanometer. We estimated by maximum likelihood the age- and sex-adjusted heritabilities from the additive polygenic component of the variance of the traits allowing for the presence of other familial correlations. We also adjusted for ascertainment (ie, for the fact that 2 siblings had to be hypertensive) and examined the effect of adjusting for body mass index, 24-hour urinary excretion of sodium and potassium, plasma renin activity, and plasma aldosterone concentration. Heritability estimates (+/-SE) for ambulatory SBP, DBP, and PP were, respectively, 0.37+/-0.12/0.24+/-0.12/0.54+/-0.12 for daytime and 0.34+/-0.13/ 0.37+/-0.15/0.47+/-0.12 for nighttime measurements (P<0.05 for all estimates). Heritability estimates for office SBP, DBP, and PP were, respectively, 0.20+/-0.11, 0.05+/-0.09, and 0.37+/-0.12. Heritability estimates for SBP varied markedly according to whether participants were treated for hypertension at baseline. The present data show that ambulatory BP and PP have a high heritability in families of African descent. They also demonstrate that antihypertensive treatment and the number of BP measurements have a major influence on the heritability estimates.