The role of antibody concentration and avidity in antiviral protection.

Neutralizing antibodies are necessary and sufficient for protection against infection with vesicular stomatitis virus (VSV). The in vitro neutralization capacities and in vivo protective capacities of a panel of immunoglobulin G monoclonal antibodies to the glycoprotein of VSV were evaluated. In vitro, neutralizing activity correlated with avidity and with neutralization rate constant, a measure of on-rate. However, in vivo, protection was independent of immunoglobulin subclass, avidity, neutralization rate constant, and in vitro neutralizing activity; above a minimal avidity threshold, protection depended simply on a minimum serum concentration. These two biologically defined thresholds of antibody specificity offer hope for the development of adoptive therapy with neutralizing antibodies.

Vitamin D levels and associated factors: a population-based study in Switzerland.

QUESTIONS UNDER STUDY: To update the prevalence of vitamin D insufficiency and to identify factors associated with vitamin D status in the Swiss adult population. METHODS: Data from the 2010-2011 Swiss Study on Salt intake, a population-based study in the Swiss population, was used. Vitamin D concentration in serum was measured by liquid chromatography- tandem mass spectrometry. Major factors that influence vitamin D levels were taken into account. Survey statistical procedures were used to estimate means and prevalences of vitamin D levels and status. Monthly-specific tertiles of vitamin D and ordinal logistic regression were used to determine the associations of covariates of interest with vitamin D status. RESULTS: The prevalences of vitamin D insufficiency (serum 25-hydroxyvitamin D: 20-29.9 ng/ml) and deficiency (<20 ng/ml) were the highest in the January-March period; 26.4% (95%CI: 21.6-31.7) and 61.6% (95%CI: 56.0-67.0), respectively. In the same period, more than 9 of ten men were vitamin D insufficient or deficient. Each unit increase of Body Mass Index was associated with an 8% decreased likelihood of being in a higher vitamin D tertiles. Oral contraceptive, altitude, urinary excretion of calcium, use of vitamin D supplement or treatment, high wine consumption, physical activity were associated with vitamin D tertiles. Compared to the French-speaking region, the Italian-speaking region was independently associated with a higher likelihood of being in higher vitamin D tertiles (OR: 1.66, 95%CI: 1.14-2.43). CONCLUSIONS: Low levels of vitamin D are common among Swiss adults, in particular during winter months and outside the Italian-speaking region.

Tandem use of solid-phase extraction and dispersive liquid-liquid microextraction for the determination of mononitrotoluenes in aquatic environment.

Solid-phase extraction (SPE) in tandem with dispersive liquid-liquid microextraction (DLLME) has been developed for the determination of mononitrotoluenes (MNTs) in several aquatic samples using gas chromatography-flame ionization (GC-FID) detection system. In the hyphenated SPE-DLLME, initially MNTs were extracted from a large volume of aqueous samples (100 mL) into a 500-mg octadecyl silane (C(18) ) sorbent. After the elution of analytes from the sorbent with acetonitrile, the obtained solution was put under the DLLME procedure, so that the extra preconcentration factors could be achieved. The parameters influencing the extraction efficiency such as breakthrough volume, type and volume of the elution solvent (disperser solvent) and extracting solvent, as well as the salt addition, were studied and optimized. The calibration curves were linear in the range of 0.5-500 μg/L and the limit of detection for all analytes was found to be 0.2 μg/L. The relative standard deviations (for 0.75 μg/L of MNTs) without internal standard varied from 2.0 to 6.4% (n=5). The relative recoveries of the well, river and sea water samples, spiked at the concentration level of 0.75 μg/L of the analytes, were in the range of 85-118%.

Réduction de la consommation de sel: opportunité, impact et stratégies. [Population reduction of salt consumption: opportunities, impact and strategies].

A national survey showed that Swiss people eat high quantity of salt (9.1 g per day on average). The Swiss Federal Office of Public Health (FOPH) has launched a strategy to reduce salt intake in the population in order to decrease cardiovascular morbidity and mortality, mainly via blood pressure reduction. The most effective public health measures are to reduce the salt content of processed food rich in salt because they do not need to change consumers' eating behaviours. The FOPH has chosen to collaborate with the food industry on a voluntary basis. Regular population-based surveys will be needed to monitor the impact of current measures on salt consumption, hypertension prevalence as well as cardiovascular morbidity and mortality in the years to come.

Usefulness of methadone plasma concentration measurement in patients receiving nevirapine or efavirenz.

Objective: To determine methadone plasma trough and peak concentrations in patients presenting opiate withdrawal symptoms after introduction of nevirapine or efavirenz. To describe the disappearance of these symptoms after methadone titration based on plasma concentrations rather than on the symptoms. Methods: Nine patients undergoing highly active antiretroviral therapy (HAART) and either nevirapine or efavirenz treatment were monitored daily for opiate withdrawal in a specialized drug addiction center. Methadone dose was titrated daily, and plasma concentrations were measured. The data are retrospective (case series). Results: Several patients complained of symptoms such as nausea, vomiting, accelerated intestinal transit, or insomnia. Even after methadone titration based on clinical symptoms, patients and health-care providers trained in infectious disease did not classify these as withdrawal symptoms and considered them as the side effects of HAART or anxiety. Methadone plasma trough concentration showed low levels of (R)- and (R,S)-methadone. Further methadone dose adjustment according to plasma level resulted in the disappearance of these withdrawal symptoms. The daily methadone dose was split when the peak/trough (R)-methadone ratio was more than 2. Conclusions: When introducing efavirenz or nevirapine to patients undergoing methadone treatment, withdrawal symptoms should be monitored, especially those such as insomnia, vomiting, or nausea. Methadone plasma trough and peak measurements can be of value in preventing unnecessary side effects of HAART.

Radioimmuno positron emission tomography with monoclonal antibodies: a new approach to quantifying in vivo tumour concentration and biodistribution for radioimmunotherapy.

Radioimmunodetection of tumours with monoclonal antibodies is becoming an established procedure. Positron emission tomography (PET) shows better resolution than normal gamma camera single photon emission tomography and can provide more precise quantitative data. Thus, in the present study, these powerful methods have been combined to perform radioimmuno PET (RI-PET). Monoclonal antibodies directed against carcinoembryonic antigen (CEA) an IgG, its F(ab')2 and a mouse-human chimeric IgG derived from it were labelled with 124I, a positron-emitting radionuclide with a convenient physical half-life of four days. Mice, xenografted with a CEA-producing human colon carcinoma, were injected with the 124I-MAb and the tumours were visualized using PET. The concentrations of 124I in tumour and normal tissue were determined by both PET and direct radioactivity counting of the dissected animals, with very good agreement. To allow PET quantification, a procedure was established to account for the presence of radioactivity during the absorption correction measurement (transmission scan). Comparison of PET and tissue counting indicates that this novel combination of radioimmunolocalization and PET (RI-PET) will provide, in addition to more precise diagnosis, more accurate radiation dosimetry for radioimmunotherapy.

Cytogenetic response to imatinib in chronic myeloid leukaemia patients: concentration dependency and associated influences under field-conditions

Introduction: Imatinib, a first-line drug for chronic myeloid leukaemia (CML), has been increasingly proposed for therapeutic drug monitoring (TDM), as trough concentrations >=1000 ng/ml (Cmin) have been associated with improved molecular and complete cytogenetic response (CCyR). The pharmacological monitoring project of EUTOS (European Treatment and Outcome Study) was launched to validate retrospectively the correlation between Cmin and response in a large population of patients followed by central TDM in Bordeaux.¦Methods: 1898 CML patients with first TDM 0-9 years after imatinib initiation, providing cytogenetic data along with demographic and comedication (37%) information, were included. Individual Cmin, estimated by non-linear regression (NONMEM), was adjusted to initial standard dose (400 mg/day) and stratified at 1000 ng/ml. Kaplan-Meier estimates of overall cumulative CCyR rates (stratified by sex, age, comedication and Cmin) were compared using asymptotic logrank k-sample test for interval-censored data. Differences in Cmin were assessed by Wilcoxon test.¦Results: There were no significant differences in overall cumulative CCyR rates between Cmin strata, sex and comedication with P-glycoprotein inhibitors/inducers or CYP3A4 inhibitors (p >0.05). Lower rates were observed in 113 young patients <30 years (p = 0.037; 1-year rates: 43% vs 60% in older patients), as well as in 29 patients with CYP3A4 inducers (p = 0.001, 1-year rates: 40% vs 66% without). Higher rates were observed in 108 patients on organic-cation-transporter-1 (hOCT-1) inhibitors (p = 0.034, 1-year rates: 83% vs 56% without). Considering 1-year CCyR rates, a trend towards better response for Cmin above 1000 ng/ml was observed: 64% (95%CI: 60-69%) vs 59% (95%CI: 56-61%). Median Cmin (400 mg/day) was significantly reduced in male patients (732 vs 899ng/ml, p <0.001), young patients <30 years (734 vs 802 ng/ml, p = 0.037) and under CYP3A4 inducers (758 vs 859 ng/ml, p = 0.022). Under hOCT-1 inhibitors, Cmin was increased (939 vs 827 ng/ml, p = 0.038).¦Conclusion: Based on observational TDM data, the impact of imatinib Cmin >1000 ng/ml on CCyR was not salient. Young CML patients (<30 years) and patients taking CYP3A4 inducers probably need close monitoring and possibly higher imatinib doses, due to lower Cmin along with lower CCyR rates. Patients taking hOCT-1 inhibitors seem in contrast to have improved CCyR response rates. The precise role for imatinib TDM remains to be established prospectively.

Blood pressure and renin-angiotensin system resetting in transgenic rats with elevated plasma Val5-angiotensinogen.

OBJECTIVE: : Increases in plasma angiotensinogen (Ang-N) due to genetic polymorphisms or pharmacological stimuli like estrogen have been associated with a blood pressure (BP) rise, increased salt sensitivity and cardiovascular risk. The relationship between Ang-N, the resetting of the renin-angiotensin system, and BP still remains unclear. Angiotensin (Ang) II-induced genetic hypertension should respond to lisinopril treatment. METHODS: : A new transgenic rat line (TGR) with hepatic overexpression of native (rat) Ang-N was established to study high plasma Ang-N. The transgene contained a mutation producing Val-Ang-II, which was measured separately from nontransgenic Ile-Ang-II in plasma and renal tissue. RESULTS: : Male homozygous TGR had increased plasma Ang-N (∼20-fold), systolic BP (ΔBP + 26 mmHg), renin activity (∼2-fold), renin activity/concentration (∼5-fold), total Ang-II (∼2-fold, kidney 1.7-fold) but decreased plasma renin concentrations (-46%, kidney -85%) and Ile-Ang-I and II (-93%, -94%) vs. controls. Heterozygous TGR exhibited ∼10-fold higher plasma Ang-N and 17 mmHg ΔBP. Lisinopril decreased their SBP (-23 vs. -13 mmHg in controls), kidney Ang-II/I (∼3-fold vs. ∼2-fold) and Ile-Ang-II (-70 vs. -40%), and increased kidney renin and Ile-Ang-I (>2.5-fold vs. <2.5-fold). Kidney Ang-II remained higher and renin lower in TGR compared with controls. CONCLUSION: : High plasma Ang-N increases plasma and kidney Ang-II levels, and amplifies the plasma and renal Ang-II response to a given change in renal renin secretion. This enzyme-kinetic amplification dominates over the Ang-II mediated feedback reduction of renin secretion. High Ang-N levels thus facilitate hypertension via small increases of Ang II and may influence the effectiveness of renin-angiotensin system inhibitors.

Impact de la consommation de sel sur la santé: les croyances de la population suisse [Impact of salt intake on health: beliefs of the Swiss population].

Excessive salt intake increases the risk of developing hypertension and cardiovascular disease. Sodium intake remains high both in developed and emerging countries. The Swiss Federal Office of Public Health has ordered a national survey on the salt intake in Switzerland, realized in different centers. This article presents the results of the awareness of the Swiss population concerning the relationship between excessive salt intake and health. This survey reveals a lack of knowledge regarding the association between high salt intake and cardiovascular disease, the sodium content of usual food, and the recommended daily value of sodium intake. Strategies to reduce salt consumption need to be reinforced by collaborations between health authorities and health care professionals.

Wheat germ cell-free expression: Two detergents with a low critical micelle concentration allow for production of soluble HCV membrane proteins.

Membrane proteins are notoriously difficult to express in a soluble form. Here, we use wheat germ cell-free expression in the presence of various detergents to produce the non-structural membrane proteins 2, 4B and 5A of the hepatitis C virus (HCV). We show that lauryl maltose neopentyl glycol (MNG-3) and dodecyl octaethylene glycol ether (C12E8) detergents can yield essentially soluble membrane proteins at detergent concentrations that do not inhibit the cell-free reaction. This finding can be explained by the low critical micelle concentration (CMC) of these detergents, which keeps the monomer concentrations low while at the same time providing the necessary excess of detergent concentration above CMC required for full target protein solubilization. We estimate that a tenfold excess of detergent micelles with respect to the protein concentration is sufficient for solubilization, a number that we propose as a guideline for detergent screening assays.

Salt subtraction in patients on maintenance hemodialysis. Efficacy and limitations.

In 6 hypertensive patients with terminal renal failure maintained on hemodialysis, the effects of 'salt subtraction' and of sequential ultrafiltrating were evaluated. Following each of 3 weekly hemodialysis sessions, salt subtraction was carried out by ultrafiltrating 1 liter and simultaneously infusing an equal volume of 5% dextrose. This resulted in a net sodium loss without hypovolemia. After a 2-week period of this procedure, the blood pressure prior to dialysis was lower (156/76 +/- 12/5 mm Hg) than after a comparable number of sequential ultrafiltration sessions (181/88 +/- 10/6 mm Hg; mean +/- SEM). This difference was not statistically significant. At the same time, body weight was comparable at 64.4 +/- 3 and 64.7 +/- 4 kg, respectively. Neither plasma renin activity nor plasma catecholamines responded with a clear increase to either procedure. The limited effect on blood pressure and the renin system of a marked sodium removal during salt subtraction suggests that sodium must still be present in excess in these patients. The procedure of salt subtraction appears safe and subjectively well tolerated, but it can probably not be used as the sole means of decreasing total body sodium without associating dietary measures to reduce sodium intake.

25-hydroxyvitamin D concentration is inversely associated with serum MMP-9 in a cross-sectional study of African American ESRD patients.

BACKGROUND: Circulating 25-hydroxyvitamin D [25(OH)D] concentration is inversely associated with peripheral arterial disease and hypertension. Vascular remodeling may play a role in this association, however, data relating vitamin D level to specific remodeling biomarkers among ESRD patients is sparse. We tested whether 25(OH)D concentration is associated with markers of vascular remodeling and inflammation in African American ESRD patients.METHODS: We conducted a cross-sectional study among ESRD patients receiving maintenance hemodialysis within Emory University-affiliated outpatient hemodialysis units. Demographic, clinical and dialysis treatment data were collected via direct patient interview and review of patients records at the time of enrollment, and each patient gave blood samples. Associations between 25(OH)D and biomarker concentrations were estimated in univariate analyses using Pearson's correlation coefficients and in multivariate analyses using linear regression models. 25(OH) D concentration was entered in multivariate linear regression models as a continuous variable and binary variable (<15 ng/ml and =15 ng/ml). Adjusted estimate concentrations of biomarkers were compared between 25(OH) D groups using analysis of variance (ANOVA). Finally, results were stratified by vascular access type.RESULTS: Among 91 patients, mean (standard deviation) 25(OH)D concentration was 18.8 (9.6) ng/ml, and was low (<15 ng/ml) in 43% of patients. In univariate analyses, low 25(OH) D was associated with lower serum calcium, higher serum phosphorus, and higher LDL concentrations. 25(OH) D concentration was inversely correlated with MMP-9 concentration (r = -0.29, p = 0.004). In multivariate analyses, MMP-9 concentration remained negatively associated with 25(OH) D concentration (P = 0.03) and anti-inflammatory IL-10 concentration positively correlated with 25(OH) D concentration (P = 0.04).CONCLUSIONS: Plasma MMP-9 and circulating 25(OH) D concentrations are significantly and inversely associated among ESRD patients. This finding may suggest a potential mechanism by which low circulating 25(OH) D functions as a cardiovascular risk factor.