A method to generate perfusable physiologic-like vascular channels within a liver-on-chip model.

The human vasculature is essential in organs and tissues for the transport of nutrients, metabolic waste products, and the maintenance of homeostasis. The integration of vessels in in vitro organs-on-chip may, therefore, improve the similarity to the native organ microenvironment, ensuring proper physiological functions and reducing the gap between experimental research and clinical outcomes. This gap is particularly evident in drug testing and the use of vascularized models may provide more realistic insights into human responses to drugs in the pre-clinical phases of the drug development pipeline. In this context, different vascularized liver models have been developed to recapitulate the architecture of the hepatic sinusoid, exploiting either porous membranes or bioprinting techniques. In this work, we developed a method to generate perfusable vascular channels with a circular cross section within organs-on-chip without any interposing material between the parenchyma and the surrounding environment. Through this technique, vascularized liver sinusoid-on-chip systems with and without the inclusion of the space of Disse were designed and developed. The recapitulation of the Disse layer, therefore, a gap between hepatocytes and endothelial cells physiologically present in the native liver milieu, seems to enhance hepatic functionality (e.g., albumin production) compared to when hepatocytes are in close contact with endothelial cells. These findings pave the way to numerous further uses of microfluidic technologies coupled with vascularized tissue models (e.g., immune system perfusion) as well as the integration within multiorgan-on-chip settings.

Short communication: Effects of in-ovo injection of endocrine disruptors and methyltransferase inhibitor on quail growth and egg-laying performances.

Early experiences, including prenatal environment, are known to influence a wide variety of mechanisms involved in the phenotype elaboration. We investigated the effect of the addition of endocrine disruptors or of a methyltransferase inhibitor during the embryonic development of quails from different genetic backgrounds (four different quail lines) on their growth and egg-laying performances. Fifty-four pairs of parents per line were used and fertilised eggs from each pair were randomly divided into five groups: a control group without any injection, an injected control group treated by injection into the egg of sesame oil, and three groups treated by injection of Genistein, Bisphenol A or 5-Aza-2'-deoxycytidine. All quails were individually weighed at 8, 21, 36 and 78 days. The age at first egg laid and the number of eggs laid were recorded. These analyses revealed a significant impact of the treatment on growth but no influence on the egg-laying traits. All three molecules significantly affected at least one of the analysed growth traits. In conclusion, we showed that the injection of endocrine disruptors or DNA methyltransferase inhibitor into the egg had significant effects on quail development; these effects were specific to each treatment, but no interaction between line and treatment was observed.

Spontaneous fertility and variable spectrum of reproductive phenotype in a family with adult-onset X-linked adrenal insufficiency harboring a novel DAX-1/NR0B1 mutation.

BACKGROUND: Adrenal hypoplasia congenita (AHC) is an X-linked disorder that affects the adrenal cortex and hypothalamus-pituitary-gonadal axis (HPG), leading to primary adrenocortical insufficiency (PAI) and hypogonadotropic hypogonadism. AHC is caused by a mutation in the DAX-1 gene (NR0B1). More commonly, this disease is characterized by early-onset PAI, with symptoms in the first months of life. However, a less severe phenotype termed late-onset AHC has been described, as PAI signs and symptoms may begin in adolescence and adulthood. Here we describe a family report of a novel mutation within NR0B1 gene and variable reproductive phenotypes, including spontaneous fertility, in a very late-onset X-linked AHC kindred. CASE PRESENTATION: Three affected maternal male relatives had confirmed PAI diagnosis between 30 y and at late 64 y. The X-linked pattern has made the endocrinology team to AHC suspicion. Regarding the HPG axis, all males presented a distinct degree of testosterone deficiency and fertility phenotypes, varying from a variable degree of hypogonadism, oligoasthenoteratozoospermia to spontaneous fertility. Interestingly, the other five maternal male relatives unexpectedly died during early adulthood, most likely due to undiagnosed PAI/adrenal crisis as the probable cause of their premature deaths. Sequencing analysis of the NR0B1 gene has shown a novel NR0B1 mutation (p.Tyr378Cys) that segregated in three AHC family members. CONCLUSIONS: NR0B1 p.Tyr378Cys segregates in an AHC family with a variable degree of adrenal and gonadal phenotypes, and its hemizygous trait explains the disease in affected family members. We recommend that NR0B1 mutation carriers, even those that are allegedly asymptomatic, be carefully monitored while reinforcing education to prevent PAI and consider early sperm banking when spermatogenesis still viable.

Fate and control of pathogenic and spoilage micro-organisms in orange blossom (Citrus aurantium) and rose flower (Rosa centifolia) hydrosols.

AIM: Hydrosols are hydrodistillation products used in food and cosmetic industries, perfumery, pharmacy and aromatherapy. The ability of preservatives to control previously reported bacterial proliferation and spoilage was evaluated. All tested preservatives were authorized for food and cosmetic application. METHODS AND RESULTS: Major pathogens of concern for foods and cosmetics were poorly able to grow in rose and orange blossom hydrosols when inoculated and incubated at 30°C. Commercial antimicrobials, such as isothiazolinone, chlorphenesin and paraben solutions, benzyl alcohol and sodium benzoate at pH = 5·0, controlled the growth of Pseudomonas and Burkholderia sp. strains representative of the natural microbiota of both hydrosols for >90 days at 30°C, only at concentrations close to the authorized limits. Concentrations of some of the tested preservatives that controlled growth at 5°C were lower than at 30°C. CONCLUSION: Pathogenic micro-organisms likely represent a low risk in rose flower and orange blossom hydrosol. However, the oligotrophic character of hydrosols and the antimicrobial properties of their essential oils do not prevent microbiological spoilage by the naturally present microbiota. SIGNIFICANCE AND IMPACT OF THE STUDY: In the absence of aseptic conditions and microbial inactivation process, only preservatives can stabilize hydrosols for a several-month storage. Several effective preservatives have been identified.

Zinc-imidazolate polymers (ZIPs) as a potential carrier to brain capillary endothelial cells.

Herein, we report the synthesis and characterization of nanospheres of a biodegradable zinc-imidazolate polymers (ZIPs) as a proof-of-concept delivery vehicle into human brain endothelial cells, the main component of the blood-brain barrier (BBB). The ZIP particles can readily encapsulate functional molecules such as fluorophores and inorganic nanoparticles at the point of synthesis producing stable colloidal dispersions. Our results show that these biodegradable particles are not cytotoxic, and are able to penetrate and release cargo species to human brain capillary endothelial cells in vitro thus exhibiting significant potential as a novel platform for brain targeting treatments.

Microarray analysis of genes with impaired insulin regulation in the skeletal muscle of type 2 diabetic patients indicates the involvement of basic helix-loop-helix domain-containing, class B, 2 protein (BHLHB2).

AIMS/HYPOTHESIS: One of the major processes by which insulin exerts its multiple biological actions is through gene expression regulation. Thus, the identification of transcription factors affected by insulin in target tissues represents an important challenge. The aim of the present study was to gain a greater insight into this issue through the identification of transcription factor genes with insulin-regulated expression in human skeletal muscle. METHODS: Using microarray analysis, we defined the sets of genes modulated during a 3 h hyperinsulinaemic-euglycaemic clamp (2 mU min(-1) kg(-1)) in the skeletal muscle of insulin-sensitive control volunteers and in moderately obese insulin-resistant type 2 diabetic patients. RESULTS: Of the 1,529 and 1,499 genes regulated during the clamp in control and diabetic volunteers, respectively, we identified 30 transcription factors with impaired insulin-regulation in type 2 diabetic patients. Analysis of the promoters of the genes encoding these factors revealed a possible contribution of the transcriptional repressor basic helix-loop-helix domain-containing, class B, 2 protein (BHLHB2), insulin regulation of which is strongly altered in the muscle of diabetic patients. Gene ontology analysis of BHLHB2 target genes, identified after BHLHB2 overexpression in human primary myotubes, demonstrated that about 10% of the genes regulated in vivo during hyperinsulinaemia are potentially under the control of this repressor. The data also suggested that BHLHB2 is situated at the crossroads of a complex transcriptional network that is able to modulate major metabolic and biological pathways in skeletal muscle, including the regulation of a cluster of genes involved in muscle development and contraction. CONCLUSIONS/INTERPRETATION: We have identified BHLHB2 as a potential novel mediator of insulin transcriptional action in human skeletal muscle.

JunD is involved in the antiproliferative effect of Delta9-tetrahydrocannabinol on human breast cancer cells.

It has been recently shown that cannabinoids, the active components of marijuana and their derivatives, inhibit cell cycle progression of human breast cancer cells. Here we studied the mechanism of Delta(9)-tetrahydrocannabinol (THC) antiproliferative action in these cells, and show that it involves the modulation of JunD, a member of the AP-1 transcription factor family. THC activates JunD both by upregulating gene expression and by translocating the protein to the nuclear compartment, and these events are accompanied by a decrease in cell proliferation. Of interest, neither JunD activation nor proliferation inhibition was observed in human non-tumour mammary epithelial cells exposed to THC. We confirmed the importance of JunD in THC action by RNA interference and genetic ablation. Thus, in both JunD-silenced human breast cancer cells and JunD knockout mice-derived immortalized fibroblasts, the antiproliferative effect exerted by THC was significantly diminished. Gene array and siRNA experiments support that the cyclin-dependent kinase inhibitor p27 and the tumour suppressor gene testin are candidate JunD targets in cannabinoid action. In addition, our data suggest that the stress-regulated protein p8 participates in THC antiproliferative action in a JunD-independent manner. In summary, this is the first report showing not only that cannabinoids regulate JunD but, more generally, that JunD activation reduces the proliferation of cancer cells, which points to a new target to inhibit breast cancer progression.

Identification and characterization of two genes (MIP-1beta, VE-CADHERIN) implicated in acute rejection in human heart transplantation: use of murine models in tandem with cDNA arrays.

BACKGROUND: Genes and mechanisms of action involved in human acute rejection after allogeneic heart transplantation remain to be elucidated. The use of a murine allograft model in tandem with cDNA arrays and quantitative real-time polymerase chain reaction (Q-PCR) can greatly help in identifying key genes implicated in human heart acute rejection. METHODS AND RESULTS: Hearts from Balb/c mice were either not transplanted or transplanted heterotopically in the abdomen of Balb/c (isografts) and C57BL/6 (allografts) mice. Histological analysis showed acute rejection only in allografts. Total RNA was extracted from isografts (n=3), allografts (n=4), and not transplanted hearts (n=4); reverse transcribed; and labeled with P32. Each probe was hybridized to cDNA macroarrays. Eight genes were overexpressed and 7 genes were underexpressed in allografts compared with isografts. Macrophage inflammatory protein-1beta (MIP-1beta), an overexpressed gene, and VE-cadherin, an underexpressed gene, were validated by immunohistochemistry and Q-PCR in the murine models. Genes of interest, validated in the 3 murine groups, were then investigated in human heart tissues. Immunohistochemistry and Q-PCR performed on endomyocardial biopsies after heart transplantation showing no rejection (n=10) or grade IB (n=10) or IIIA (n=10) rejection, according to International Society of Heart and Lung Transplantation criteria, confirmed the results obtained from the murine model. CONCLUSIONS: We have demonstrated that the upregulation of MIP-1beta and downregulation of VE-cadherin may strongly participate in human acute heart rejection.

[Is the white coat effect an alert reaction?]. / L'effet blouse blanche est-il une réaction d'alerte?

Is the white coat effect an alert reaction? In this cross-sectional study we compared the white coat effect on systolic blood pressure with the systolic blood pressure reactivity obtained during a stress test. The influence of the sympathetic system (LF band of systolic BP) and the parasympathetic system (HF band of pulse rate) on white coat systolic blood pressure and stress test systolic blood pressure were analysed. We stratified 174 subjects into two groups, according to their blood pressure: hypertensives (HT, n=44, BP>140/90 mmHg) and normotensives (NT, n=130). The BP was recorded during an occupational health consultation, over 24 hours, and beat to beat during a stress test (Finapress). White coat systolic BP was calculated as the difference between the consultation BP and the average systolic BP over 24 hours. The white coat systolic BP was not related with an increase in pulse rate. In contrast, during the stress test the increases in systolic BP and pulse rate were correlated (r=0.44; p<0.001). The white coat systolic BP was lower than the stress test systolic BP in the NT (6.6 +/- 7.2 vs 23 +/- 12 mmHg; p<0.001) and in the HT (16 +/- 11 vs 29 +/- 17 mmHg; p<0.001). The HT had a lower parasympathetic index than the NT (0.45 +/- 0.43 vs 0.92 +/- 0.83 bpm2; p<0.001). In the HT the white coat systolic BP was positively correlated with the stress test systolic BP (r=0.47: p<0.01) and negatively with the parasympathetic activity index. In conclusion, for recently diagnosed and untreated HT an early alteration of the parasympathetic system reveals that the white coat effect is a low amplitude alert reaction.

[Markers of cardiovascular remodeling in hypertension]. / Marqueurs du remodelage cardiovascularire structural et fonctionnel dans l'hypertension.

UNLABELLED: Our goal was to study the relative influence of systolic blood pressure (SBP) and plasmatic markers of sympathetic and renin-aldosterone systems (RAS) activities to left atrial diameter (LAD), left ventricular posterior wall thickness (LVPWT) and pulse wave velocity (PWV), which reflect cardiovascular remodeling in hypertension. METHODS: In 227 consecutive patients with hypertension (mean age +/- SD: 53.3 years +/- 13.4, 126 men), we measured: PWV, LAD, LVPWT, mean 24-hours SBP, plasma renin activity, and plasma aldosterone and catecholamine levels. Multiples linear regression analyses were performed to test statistical associations between hemodynamic and neurohumoral factors, and cardiovascular remodeling parameters, after adjustment for age, gender and body mass index. RESULTS: LVPWT was positively correlated to SBP as well as to plasma aldosterone and meta-noradrenaline (p < 0.001). LAD and PWV were related to SBP but not to any of the biological variables. Moreover, LAD correlated to PWV independently of SBP (p < 0.05), whereas after SBP inclusion in the model, there was not significant correlation between LAD and LVPWT nor between LVPWT and PWV. CONCLUSION: In hypertension, the development of cardiac hypertrophy depends on SBP and the sympathetic and renin-aldosterone systems activities. The RAS is not involved in the PWV nor LAD modifications. Strong association between LAD and PWV suggest that left atrial enlargement, that may be considered as a marker of diastolic function, may results more from arterial stiffness than from ventricular hypertrophy.

[Risk profiles of hypertension in normotensive subjects]. / Profils de risque d'hypertension artérielle chez le normotendu.

The aim of this study was to evaluate the influence of 10 factors suspected to be involved in hypertension genesis (age, body mass index, alcohol consumption, sodium to potassium urinary excretion ratio, systolic BP and heart rate response to mental stress, baroreflex sensitivity (BRS), job demand, job latitude (Karasec's questionnaire), and personality (Bortner's score). A cohort of 213 normotensive healthy subjects was followed during five years. Using K-means clustering technique we have defined 7 homogeneous groups of subjects. Four groups with different combinations of these factors had a significantly higher 5-year systolic BP increase. The common characteristic of these groups was a low BRS. In conclusion, cluster analysis is well suited to analyse combined effect of factors on hypertension genesis. Only low BRS seems to be the common factor involved in hypertension development.

[Expression of cytokines and their receptors in left ventricular hypertrophy in TGR(mRen2)27 rats]. / Expression des cytokines et de leurs récepteurs dans le ventricule gauche hypertrophique du rat TGR(mRen2)27.

Variations in the expression of cytokines from the interleukin-6 (IL-6) family: ciliary neurotrophic factor (CNTF), leukaemia inhibitory factor (LIF), and cardiotrophin 1 (CT-1) were studied during cardiac remodelling leading to left ventricular hypertrophy (LVH) in TGR(mRen2)27 rats at the age of 8 and 20 weeks. The cytokines mRNA levels within the free wall of the left ventricle were measured by semi-quantitative RT-PCR standardised with 18S. They were compared between heterozygous rats for the mRen2 transgene (TG+/-) and control rats (TG-/-). No significant difference was observed between results obtained at 8 and 20 weeks of age. At 20 weeks of age, TGR(mRen2)27 rats showed higher levels of mRNA LIF and IL-6 respectively by 52 and 55% compared to the control rats [LIF TG+/-: 3.17 +/- 0.21, TG-/-: 2.09 +/- 0.03; p < 0.001; n = 5; and IL-6 TG+/-: 1.53 +/- 0.13; TG-/-: 0.99 +/- 0.17; p < 0.05; n = 5]. By contrast, no variation of mRNAs levels of CT-1 and gp 130 genes was observed between control and transgenic rats. Concerning the cytokine receptors, the levels of mRNA for IL-6R did not vary while those of receptor subunits LIFR and CNTFR were decreased respectively by 48 and 42% in transgenic rats vs controls [LIFR TG+/-: 0.48 +/- 0.01; TG-/-: 0.92 +/- 0.08 p < 0.001; n = 5; and CNTFR TG+/-: 1.07 +/- 0.08; TG-/-: 1.85 +/- 0.18; p < 0.01; n = 5]. Therefore, these results show a specific pattern of activation of the cytokines pathway in the LVH of the TGR(mRen2)27 rat.

Renal elimination of amikacin and the aging process.

OBJECTIVE: Although amikacin is primarily eliminated via glomerular filtration, drug concentrations are not consistently predicted in all patients. To better describe the relationship between amikacin clearance and both age and renal function, we used a new heuristic approach involving statistical analysis of dependence. DESIGN AND SETTING: Retrospective pharmacokinetic study using data from seven centres in France. PARTICIPANTS: 634 patients with sepsis aged between 18 and 98 years of age who received intravenous amikacin. METHODS: Clearance of amikacin was modelled using the NonParametric EM algorithm for a two-compartment model (NPEM2) with intravenous infusion. RESULTS: A total of 2499 serum amikacin determinations was available for analysis. The relationship between the clearance of amikacin and age was weak. Interestingly, the Z method, which filters data based on dependence criteria, selected data that were best fitted by a polynomial function (r = 0.90; p < 0.001). This representation of the polynomial function was similar to a previously proposed theoretical model describing covariations between the clearance of amikacin and age. However, the polynomial function applied to only 33% of the patients that were selected by the Z method. The correlation between the clearance of amikacin and renal function was also relatively low (r = 0.39). The Z method exhibited a continuous and strong dependence pattern between the clearance of amikacin and age for 49% of the patients. CONCLUSIONS: The Z methodology, which filters data using dependence criteria, confirms that age, renal function and amikacin clearance are strongly related, but only in less than half of a large sample of patients with sepsis without renal pathology. These results suggest that other variables should be taken into account in order to improve the description of the behaviour of amikacin. The Z methodology improved the classical description of relationships between variables, and should be applied to better select pertinent variables in pharmacokinetic studies.

Limits of clinical tests to screen autonomic function in diabetes type 1.

OBJECTIVES: A precocious detection of cardiac autonomic dysfunction is of major clinical interest that could lead to a more intensive supervision of diabetic patients. However, classical clinical exploration of cardiac autonomic function is not easy to undertake in a reproducible way. Thus, respective interests of autonomic nervous parameters provided by both clinical tests and computerized analysis of resting blood pressure were checked in type 1 diabetic patients without orthostatic hypotension and microalbuminuria. MATERIAL AND METHODS: Thirteen diabetic subjects matched for age and gender to thirteen healthy subjects volunteered to participate to the study. From clinical tests (standing up, deep breathing, Valsalva maneuver, handgrip test), autonomic function was scored according to Ewing's methodology. Analysis of resting beat to beat blood pressure provided autonomic indices of the cardiac function (spectral analysis or Z analysis). RESULTS: 5 of the 13 diabetic patients exhibited a pathological score (more than one pathological response) suggesting the presence of cardiovascular autonomic dysfunction. The most discriminative test was the deep breathing test. However, spectral indices of BP recordings and baro-reflex sensitivity (BRS) of these 5 subjects were similar to those of healthy subjects and of remaining diabetic subjects. CONCLUSION: Alteration in Ewing's score given by clinical tests may not reflect an alteration of cardiac autonomic function in asymptomatic type 1 diabetic patients, because spectral indices of sympathetic and parasympathetic (including BRS) function were within normal range. Our results strongly suggest to confront results provided by both methodologies before concluding to an autonomic cardiac impairment in asymptomatic diabetic patients.

Time versus frequency domain techniques for assessing baroreflex sensitivity.

BACKGROUND: Newer techniques to evaluate baroreflex sensitivity (BRS) are based on the analysis of blood pressure (BP) and heart rate (HR) time series in the time or frequency domain. These novel approaches are steadily gaining popularity, since they do not require injection of vasoactive substances, nor do they rely on a complex experimental set-up. AIM: This review outlines and compares some basic features of the latest methods to assess spontaneous baroreflex function. RESULTS: Modern techniques for the estimation of spontaneous BRS are based on a variety of signal processing schemes and derive information on the baroreflex function from different perspectives. Thus factors such as respiration and other non-stationary agents may have different influences on the estimates provided by each of these approaches. Notwithstanding such individual specificity, however, it has been observed that in several physiological and pathophysiological conditions these techniques often provide comparable information on BRS changes over time, particularly when the estimates are averaged over time windows of a few minutes. CONCLUSIONS: Due to the general agreement in the pattern of BRS among most modern methods, it seems reasonable to employ the most validated of these techniques, for which data obtained in several studies are already available.

Beat-to-beat stroke volume estimation from aortic pressure waveform in conscious rats: comparison of models.

Several methods for estimating stroke volume (SV) were tested in conscious, freely moving rats in which ascending aortic pressure and cardiac flow were simultaneously (beat-to-beat) recorded. We compared two pulse-contour models to two new statistical models including eight parameters extracted from the pressure waveform in a multiple linear regression. Global as well as individual statistical models gave higher correlation coefficients between estimated and measured SV (model 1, r = 0.97; model 2, r = 0.96) than pulse-contour models (model 1, r = 0.83; model 2, r = 0.91). The latter models as well as statistical model 1 used the pulsatile systolic area and thus could be applied to only 47 +/- 17% of the cardiac beats. In contrast, statistical model 2 used the pressure-increase characteristics and was therefore established for all of the cardiac beats. The global statistical model 2 applied to data sets independent of those used to establish the model gave reliable SV estimates: r = 0.54 +/- 0.07, a small bias between -8% to +10%, and a mean precision of 7%. This work demonstrated the limits of pulse-contour models to estimate SV in conscious, unrestrained rats. A multivariate statistical model using eight parameters easily extracted from the aortic waveform could be applied to all cardiac beats with good precision.

Influence of clinical history on airways bacterial colonization in subjects with chronic tracheostomy.

Patients with chronic tracheostomy are subject to significant bacterial colonization of the airways, a risk factor for respiratory infections. The aim of our study was to verify whether bacterial colonization and humoral immune response in the airways can be influenced by the disease which led to chronic respiratory failure and tracheostomy. Thirty-nine clinically stable outpatients with chronic tracheostomy were considered: 24 were affected by chronic obstructive pulmonary disease (COPD) (mean age 66 years, range 54-78, M/F 19/3; months since tracheostomy 23, range 3-62), 15 by restrictive lung disease (RLD) (12 thoracic wall deformities, three neuromuscular disease; age 57 years, range 41-72; M/F 3/12, months since tracheostomy 22, range 2-68). Recent antibiotic or corticosteroid treatments (< 1 month) were among exclusion criteria. Bacterial counts were assessed in tracheobronchial secretions with the method of serial dilutions. Identification of bacterial strains was performed by routine methods. Albumin, IgG, A, and M were measured in airways secretions with an immunoturbidimetric method. No significant differences were found between the two groups as regards either the quantitative bacterial cultures (RLD 81.4, 2.6-4200 x 10(4); COPD 75.9, 1.0-1530 x 10(4) colony forming units (cfu)/ml, geometric mean, range) or the prevalence of the main bacterial strains, (Pseudomonas species: 38 and 37%, Serratia marcescens: 31 and 23%, Staphylococcus aureus: 14 and 6%, Proteus species: 3 and 8%, for RLD and COPD respectively) as a percentage of total strains isolated (RLD = 26, COPD = 48). Immunoglobulin levels did not show significant differences, apart from being higher in underweight subjects. We conclude that in our series of stable outpatients with chronic tracheostomy, bacteria-host interaction in the airways was not influenced by the clinical history.

Mental stress-induced increase in blood pressure is not related to baroreflex sensitivity in middle-aged healthy men.

The baroreflex that acts to blunt blood pressure (BP) variations through opposite variations in heart rate should limit the BP increase produced by an emotional challenge. However, relations between baroreflex sensitivity and BP reactivity induced by a psychological stress in a large group of adults have never been firmly established. In 280 healthy men, rest (10 minutes) and stress (5 minutes) BP and heart rate were recorded beat to beat by a blood pressure monitor. The mental stress was elicited by a well-standardized computerized version of a word color conflict stress test (Stroop Color Test). Rest and stress baroreflex sensitivity was assessed by the cross-spectral analysis of BP and heart rate and by the sequence method. The stress-induced increase in systolic BP (22.4+/-0.1 mm Hg) was not correlated with resting baroreflex sensitivity but was slightly correlated (r=0.2, P<0.001) with BP variability assessed either by standard deviation or by mid-frequency band spectral power. Our results suggested that a centrally mediated sympathetic stimulation overcame cardiac autonomic regulation and emphasized the role of the sympathetic vasoconstriction in the pressure response at the onset of the stressing stimulation. During the sustained sympathoexcitatory phase, the cardiac baroreflex blunts BP variations but at a lower sensitivity.

In vivo efficacy of mefloquine for the treatment of Falciparum malaria in Brazil.

Ninety-four patients with falciparum malaria were treated with mefloquine (1000-mg single dose) and remained hospitalized in a malaria-free area for a minimum of 28 days. There was 1 parasitologic failure (grade I resistance [RI]) for a 99% cure rate (95% confidence interval, 94.2%-99.7%). Mean parasite clearance time by thick smear was 45.7 h (SD, 11.4 h). The subject in whom therapy failed had a parasite clearance time (71 h) >2 SD above the population mean. His plasma mefloquine level 48 h after administration was lower (578 ng/mL) than the range of levels from 8 randomly selected cured subjects (834-2360 ng/mL). The IC50 to mefloquine for the recrudescent strain of the RI failure was in the upper 90th percentile of IC50 values from 30 cured subjects. These results show a high mefloquine cure rate but document the onset and mechanism of the emergence of resistance.