Stroke Volume Recruitability during the Third Trimester of Pregnancy.

OBJECTIVE: It is unknown whether the heart operates in the ascending or flat portion of the Starling curve during normal pregnancy. Pregnant women do not respond to the passive leg-raising maneuver secondary to mechanical obstruction of the inferior vena cava by the gravid uterus. Our objective was to evaluate if administration of a fluid bolus increases baseline stroke volume (SV) among healthy pregnant patients during the third trimester. STUDY DESIGN: Healthy pregnant women who underwent elective term cesarean sections were included. A noninvasive cardiac output monitor was used to measure hemodynamic variables at baseline and after administration of a 500-mL crystalloid bolus. RESULTS: Forty-five women were included in the study. Fluid administration was associated with a statistically significant increase in SV from a baseline value of 71 ± 11 to 90 ± 19 mL (95% confidence interval [CI]: 13.67-21.49; p < 0.01) and a significant decrease in maternal heart rate from a baseline of 87 ± 9 beats per minute to 83 ± 8 after the fluid bolus (95% CI: -6.81 to -2.78; p = 0.03). No changes in peripheral vascular resistances or any other measured hemodynamic parameters were noted with volume expansion. CONCLUSION: In healthy term pregnancy, the heart operates in the ascending portion of the Starling's curve, rendering it fluid responsive.

Remote control of neuronal signaling.

A significant challenge for neuroscientists is to determine how both electrical and chemical signals affect the activity of cells and circuits and how the nervous system subsequently translates that activity into behavior. Remote, bidirectional manipulation of those signals with high spatiotemporal precision is an ideal approach to addressing that challenge. Neuroscientists have recently developed a diverse set of tools that permit such experimental manipulation with varying degrees of spatial, temporal, and directional control. These tools use light, peptides, and small molecules to primarily activate ion channels and G protein-coupled receptors (GPCRs) that in turn activate or inhibit neuronal firing. By monitoring the electrophysiological, biochemical, and behavioral effects of such activation/inhibition, researchers can better understand the links between brain activity and behavior. Here, we review the tools that are available for this type of experimentation. We describe the development of the tools and highlight exciting in vivo data. We focus primarily on designer GPCRs (receptors activated solely by synthetic ligands, designer receptors exclusively activated by designer drugs) and microbial opsins (e.g., channelrhodopsin-2, halorhodopsin, Volvox carteri channelrhodopsin) but also describe other novel techniques that use orthogonal receptors, caged ligands, allosteric modulators, and other approaches. These tools differ in the direction of their effect (activation/inhibition, hyperpolarization/depolarization), their onset and offset kinetics (milliseconds/minutes/hours), the degree of spatial resolution they afford, and their invasiveness. Although none of these tools is perfect, each has advantages and disadvantages, which we describe, and they are all still works in progress. We conclude with suggestions for improving upon the existing tools.

Maternal and Neonatal Outcomes of Pregnancy within 7 years after Roux-Y Gastric Bypass or Sleeve Gastrectomy Surgery.

PURPOSE: Few studies examine whether maternal and neonatal outcomes differ by time from metabolic and bariatric surgery (MBS) to conception. We describe maternal and neonatal outcomes among women with pregnancy after Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) overall and by whether conception occurred during the period when pregnancy is not recommended (< 18 months postoperative) versus later. MATERIALS AND METHODS: A prospective cohort study enrolled 135 US adult women (median age, 30 years, body mass index [BMI], 47.2 kg/m2) who underwent RYGB or SG (2006-2009) and subsequently reported ≥ 1 pregnancy within 7 years. Participants self-reported pregnancy-related information annually. Differences in prevalence of maternal and neonatal outcomes by postoperative conception timeframe (< 18 versus ≥ 18 months) were assessed. RESULTS: Thirty-one women reported ≥ 2 postoperative pregnancies. At time of postoperative conception (median 26 [IQR:22-52] months postoperative) median BMI was 31 (IQR:27-36) kg/m2. Excessive gestational weight gain (55%), cesarean section (42%) and preterm labor or rupture of membranes (40%) were the most common maternal outcomes. Forty percent of neonates had a composite outcome of still birth (1%), preterm birth (26%), small for gestational age (11%), or neonatal intensive care unit admission (8%). Prevalence of outcomes did not statistically significantly differ by timeframe. CONCLUSION: In US women who conceived ≤ 7 years following RYGB or SG, 40% of neonates had the composite neonatal outcome. The prevalence of maternal and neonatal outcomes post-MBS were not statistically significant by conception timeframe.

Management of Viral Complications of Pregnancy: Pharmacotherapy to Reduce Vertical Transmission.

Viral infections are common complications of pregnancy. Although some infections have maternal sequelae, many viral infections can be perinatally transmitted to cause congenital or chronic infection in fetuses or infants. Treatments of such infections are geared toward reducing maternal symptoms and complications and toward preventing maternal-to-child transmission of viruses. The authors review updates in the treatment of herpes simplex virus, cytomegalovirus, hepatitis B and C viruses, human immunodeficiency virus, and COVID-19 during pregnancy.

Early Pregnancy Blood Pressure Elevations and Risk for Maternal and Neonatal Morbidity.

OBJECTIVE: To investigate whether women with early pregnancy elevated blood pressure (BP) or stage 1 hypertension exhibit increased risk of preeclampsia and maternal or neonatal morbidity. METHODS: We conducted a clinical cohort study of 18,162 women who delivered a singleton neonate from 2015 to 2018 and attended at least two prenatal appointments before 20 weeks of gestation. Data were collected within the Magee Obstetric Maternal and Infant database, an aggregate of prenatal and delivery health records. Early pregnancy BP was defined as average BP before 20 weeks of gestation, and women were classified with normal, elevated BP, stage 1 or 2 hypertension according to current guidelines. The primary outcome was preeclampsia. Secondary outcomes were severe maternal morbidity, placental abruption, gestational diabetes, and composite neonatal morbidity. RESULTS: Overall, 75.2% of the women were categorized with normal BP, 13.9% with elevated BP, 5.4% with stage 1 hypertension, and 5.5% with stage 2 hypertension. Risk of preeclampsia increased in a stepwise fashion with increasing BP category, adjusted for covariates (normal BP, 4.7%, referent; elevated BP, 7.3%, adjusted odds ratio [aOR] 1.29, 95% CI 1.07-1.56; stage 1, 12.3%, aOR 2.35, 95% CI 1.86-2.96), and stage 2, 30.2%, aOR 6.49, 95% CI 5.34-7.89). Results were similar among black and white women. Gestational diabetes was more prevalent among women with stage 1 (11.4%; aOR 1.50, 95% CI 1.18-1.91] and stage 2 hypertension (14.2%; aOR 1.65, 95% CI 1.30-2.10). Severe maternal morbidity and neonatal morbidity were increased only among women with stage 2 hypertension (aOR 2.99, 95% CI 2.26-3.99, and aOR 2.67, 95% CI 2.28-3.12, respectively). CONCLUSION: Women with elevated BP, and stage 1 and 2 hypertension in early pregnancy are at increased risk for preeclampsia. These findings emphasize the importance of applying the 2017 BP guidelines to reproductive-aged women. Strategies to incorporate these guidelines into obstetric care may also be warranted.

Parallel functional activity profiling reveals valvulopathogens are potent 5-hydroxytryptamine(2B) receptor agonists: implications for drug safety assessment.

Drug-induced valvular heart disease (VHD) is a serious side effect of a few medications, including some that are on the market. Pharmacological studies of VHD-associated medications (e.g., fenfluramine, pergolide, methysergide, and cabergoline) have revealed that they and/or their metabolites are potent 5-hydroxytryptamine(2B) (5-HT(2B)) receptor agonists. We have shown that activation of 5-HT(2B) receptors on human heart valve interstitial cells in vitro induces a proliferative response reminiscent of the fibrosis that typifies VHD. To identify current or future drugs that might induce VHD, we screened approximately 2200 U.S. Food and Drug Administration (FDA)-approved or investigational medications to identify 5-HT(2B) receptor agonists, using calcium-based high-throughput screening. Of these 2200 compounds, 27 were 5-HT(2B) receptor agonists (hits); 14 of these had previously been identified as 5-HT(2B) receptor agonists, including seven bona fide valvulopathogens. Six of the hits (guanfacine, quinidine, xylometazoline, oxymetazoline, fenoldopam, and ropinirole) are approved medications. Twenty-three of the hits were then "functionally profiled" (i.e., assayed in parallel for 5-HT(2B) receptor agonism using multiple readouts to test for functional selectivity). In these assays, the known valvulopathogens were efficacious at concentrations as low as 30 nM, whereas the other compounds were less so. Hierarchical clustering analysis of the pEC(50) data revealed that ropinirole (which is not associated with valvulopathy) was clearly segregated from known valvulopathogens. Taken together, our data demonstrate that patterns of 5-HT(2B) receptor functional selectivity might be useful for identifying compounds likely to induce valvular heart disease.

Treatment of Viral Infections During Pregnancy.

Viral infections are common complications of pregnancy. Although some infections have maternal sequelae, many viral infections can be perinatally transmitted to cause congenital or chronic infection in fetuses or infants. Treatments of such infections are geared toward reducing maternal symptoms and complications and toward preventing maternal-to-child transmission of viruses. This article reviews the treatment of herpes simplex virus, cytomegalovirus, hepatitis B and C viruses, and human immunodeficiency virus during pregnancy.

Rapid, reversible activation of AgRP neurons drives feeding behavior in mice.

Several different neuronal populations are involved in regulating energy homeostasis. Among these, agouti-related protein (AgRP) neurons are thought to promote feeding and weight gain; however, the evidence supporting this view is incomplete. Using designer receptors exclusively activated by designer drugs (DREADD) technology to provide specific and reversible regulation of neuronal activity in mice, we have demonstrated that acute activation of AgRP neurons rapidly and dramatically induces feeding, reduces energy expenditure, and ultimately increases fat stores. All these effects returned to baseline after stimulation was withdrawn. In contrast, inhibiting AgRP neuronal activity in hungry mice reduced food intake. Together, these findings demonstrate that AgRP neuron activity is both necessary and sufficient for feeding. Of interest, activating AgRP neurons potently increased motivation for feeding and also drove intense food-seeking behavior, demonstrating that AgRP neurons engage brain sites controlling multiple levels of feeding behavior. Due to its ease of use and suitability for both acute and chronic regulation, DREADD technology is ideally suited for investigating the neural circuits hypothesized to regulate energy balance.

Directed molecular evolution of DREADDs: a generic approach to creating next-generation RASSLs.

G protein-coupled receptors (GPCRs) and their downstream signaling cascades contribute to most physiological processes and a variety of human diseases. Isolating the effects of GPCR activation in an in vivo experimental setting is challenging as exogenous ligands have off-target effects and endogenous ligands constantly modulate the activity of native receptors. Highly specific designer drug-designer receptor complexes are a valuable tool for elucidating the effects of activating particular receptors and signaling pathways within selected cell types in vivo. In this study, we describe a generic protocol for the directed molecular evolution of designer receptors exclusively activated by designer drugs (DREADDs). First, the yeast system is validated with the template receptor. Second, a mutant library is generated by error-prone PCR. Third, the library is screened by drug-dependent yeast growth assays. Mutants exhibiting the desired properties are selected for further rounds of mutagenesis or for characterization in mammalian systems. In total, these steps should take 6-8 weeks of experimentation and should result in the evolution of a receptor to be activated by the chosen ligand. This protocol should help improve the experimental targeting of select cell populations.

Remote control of neuronal activity in transgenic mice expressing evolved G protein-coupled receptors.

Examining the behavioral consequences of selective CNS neuronal activation is a powerful tool for elucidating mammalian brain function in health and disease. Newly developed genetic, pharmacological, and optical tools allow activation of neurons with exquisite spatiotemporal resolution; however, the inaccessibility to light of widely distributed neuronal populations and the invasiveness required for activation by light or infused ligands limit the utility of these methods. To overcome these barriers, we created transgenic mice expressing an evolved G protein-coupled receptor (hM3Dq) selectively activated by the pharmacologically inert, orally bioavailable drug clozapine-N-oxide (CNO). Here, we expressed hM3Dq in forebrain principal neurons. Local field potential and single-neuron recordings revealed that peripheral administration of CNO activated hippocampal neurons selectively in hM3Dq-expressing mice. Behavioral correlates of neuronal activation included increased locomotion, stereotypy, and limbic seizures. These results demonstrate a powerful chemical-genetic tool for remotely controlling the activity of discrete populations of neurons in vivo.

Engineered GPCRs as tools to modulate signal transduction.

Different families of G-protein-coupled receptors (GPCRs) have been engineered to provide exclusive control over the activation of these receptors and thus to understand better the consequences of their signaling in vitro and in vivo. These engineered receptors, named RASSLs (receptors activated solely by synthetic ligands) and DREADDs (designer receptors exclusively activated by designer drugs), are insensitive to their endogenous ligands but can be activated by synthetic drug-like compounds. Currently, the existing RASSLs and DREADDs cover the Gi, Gq, and Gs signaling pathways. These modified GPCRs can be utilized as ideal tools to study GPCR functions selectively in specific cellular populations.