Strong ion and weak acid analysis in severe preeclampsia: potential clinical significance

BACKGROUND

The influence of common disturbances seen in preeclampsia, such as changes in strong ions and weak acids (particularly albumin) on acid-base status, has not been fully elucidated. The aims of this study were to provide a comprehensive acid-base analysis in severe preeclampsia and to identify potential new biological predictors of disease severity.

METHODS

Fifty women with severe preeclampsia, 25 healthy non-pregnant- and 46 healthy pregnant controls (26-40 weeks' gestation), were enrolled in this prospective case-control study. Acid-base analysis was performed by applying the physicochemical approach of Stewart and Gilfix.

RESULTS

Mean [sd] base excess was similar in preeclamptic- and healthy pregnant women (-3.3 [2.3], and -2.8 [1.5] mEq/L respectively). In preeclampsia, there were greater offsetting contributions to the base excess, in the form of hyperchloraemia (BE(Cl) -2 [2.3] vs -0.4 [2.3] mEq/L, P<0.001) and hypoalbuminaemia (BE(Alb) 3.6 [1] vs 2.1 [0.8] mEq/L, P<0.001). In preeclampsia, hypoalbuminaemic metabolic alkalosis was associated with a non-reassuring/abnormal fetal heart tracing (P<0.001). Quantitative analysis in healthy pregnancy revealed respiratory and hypoalbuminaemic alkalosis that was metabolically offset by acidosis, secondary to unmeasured anions and dilution.

CONCLUSIONS

While the overall base excess in severe preeclampsia is similar to that in healthy pregnancy, preeclampsia is associated with a greater imbalance offsetting hypoalbuminaemic alkalosis and hyperchloraemic acidosis. Rather than the absolute value of base excess, the magnitude of these opposing contributors may be a better indicator of the severity of this disease. Hypoalbuminaemic alkalosis may also be a predictor of fetal compromise.

CLINICAL TRIAL REGISTRATION

clinicaltrials.gov: NCT 02164370.

Retinoic acid modulation of CD8 effector and memory differentiation. (110.4)

A plethora of work implicates important effects of the Vitamin A derivative, retinoic acid (RA), in myeloid differentiation, while fewer studies explore the role of RA on lymphoid cells. Most work has looked at the role of RA on CD4 T cells, focusing on regulatory CD4 T cell differentiation and maintenance of this phenotype along with some Th1 functions. There is little information about the role of RA in CD8 T cell differentiation, and even less on cell-intrinsic effects in the CD8 T cell. In this study we explored the role of RA on effector and memory differentiation in a direct and cell intrinsic manner in the context of vaccinia virus infection. We used dominant negative RA alpha-receptor (RARα DN) expressing mice and bone marrow chimeric mice containing both WT and RARα DN compartments. We observed the loss of the short-lived effector cell phenotype and an enhanced memory precursor phenotype at the effector and contraction phase of the CD8 response in the absence of RA signaling. Further, the lack of RA increased the proportion of central memory CD8s. Vitamin A is used in conjunction with various vaccines (e.g. Measles vaccine), these results will elucidate the effect of RA in shaping the effector and memory response helping to tailor the supplement to better enhance the outcome of vaccination.

MiR-155 modulates effector and memory CD8 T cell differentiation in response to murine γ herpes virus. (110.13)

MicroRNAs (miRNAs) have emerged as a major regulatory network with profound effects on many physiological processes. They are particularly important for determining cell fate decisions. Several processes mediate CD8 T cell differentiation. While many studies have revealed the importance of transcriptional and epigenetic regulation, it is likely that miRNAs also contribute to this programming. miRNAs are critical in determining B and CD4 T cell lineage, yet little is known about their effect on CD8 T cell differentiation. Studies with in vitro skewed central memory CD8 T cells show a down regulation of miR-155 relative to skewed effector memory cells. Using murine gammaherpesvirus 68 as a model, we examined the influence of miR-155 on CD8 differentiation in vivo. Our results showed lowered CD8 responses in the absence of miR-155 accompanied by a phenotypic skewing towards a memory precursor phenotype at the acute phase, which resulted in more central memory cells. The resulting memory cells in the absence of miR-155 were as functionally competent as their wild type counterparts, as revealed by their ability to recall to the same antigen. Our data indicate the importance of mIR-155 in effector differentiation, which may be a critical piece of the puzzle in CD8 differentiation giving useful information for vaccine research.

Increased noradrenergic activity in prefrontal cortex slices of an animal model for attention-deficit hyperactivity disorder--the spontaneously hypertensive rat

Spontaneously hypertensive rats (SHR) are used as a model for attention-deficit/hyperactivity disorder (ADHD) since SHR are hyperactive and they show defective sustained attention in behavioral tasks. Using an in vitro superfusion technique we showed that norepinephrine (NE) release from prefrontal cortex slices of SHR was not different from that of their Wistar-Kyoto (WKY) control rats when stimulated either electrically or by exposure to buffer containing 25 mM K(+). The monoamine vesicle transporter is, therefore, unlikely to be responsible for the deficiency in DA observed in SHR, since, in contrast to DA, vesicle stores of NE do not appear to be depleted in SHR. In addition, alpha(2)-adrenoceptor mediated inhibition of NE release was reduced in SHR, suggesting that autoreceptor function was deficient in prefrontal cortex of SHR. So, while DA neurotransmission appears to be down-regulated in SHR, the NE system appears to be under less inhibitory control than in WKY suggesting hypodopaminergic and hypernoradrenergic activity in prefrontal cortex of SHR. These findings are consistent with the hypothesis that the behavioral disturbances of ADHD are the result of an imbalance between NE and DA systems in the prefrontal cortex, with inhibitory DA activity being decreased and NE activity increased relative to controls.