Lactate production as a response to intrapartum hypoxia in the growth-restricted fetus

Immunohistochemical localization of HCA1 receptor in placenta in presence of fetal growth restriction

INTRODUCTION

Glucose metabolism produces lactate and hydrogen ions in an anaerobic environment. Fetuses with intrauterine growth restriction are considered to become progressively lactacidemic as well as hypoxic. Roles of lactate in the placenta in the presence of fetal growth restriction (FGR) remain to be clarified.

METHODS

Immunohistochemical localization of lactate-related substances, such as a receptor for lactate (hydroxy-carboxylic acid 1 receptor (HCA1 receptor/GPR81)), monocarboxylate transporters (MCTs) for lactate, lactate dehydrogenases (LDHs), and proteins expressed in syncytiotrophoblasts or cytotrophoblasts was examined in placentas of appropriate weight for gestational age (AGA) fetus and those showing FGR.

RESULTS

Immunoreactivity for the HCA1 receptor was present in the cytoplasm of some trophoblasts, predominantly localized to their basal (fetus-facing) side, and was frequently colocalized with that for E-cadherin or serine peptidase inhibitor, Kunitz type 1 (SPINT1), a marker protein of cytotrophoblasts. Immunoreactivity for MCT1 and MCT4 was present on the basal and the microvillous (maternal-facing) membranes of trophoblasts in both groups, respectively. Clear immunoreactivity for LDHA and LDHB was also observed in the cytoplasm of trophoblasts, mainly localized to their basal side. However, there were no significant differences in immunohistochemically stained areas of lactate-related substances between AGA and late-onset FGR groups. On the other hand, there were correlations between coefficients of the presence of chorioamnionitis and the values of LDHB and E-cadherin.

DISCUSSION

Immunohistochemical localization of the HCA1 receptor was predominantly observed in the cytoplasm located on the basal side of trophoblasts, suggesting a role of lactate in human placental development, including syncytialization.

Preparation of Conductive Cellulose Coated with Conductive Polymer and Its Application in the Detection of pH and Characteristic Substances in Sweat

Rich biological information in sweat provides great potential for health monitoring and management. However, due to the complexity of sweat, the development of environmentally friendly green electronic products is of great significance to the construction of ecological civilization. This study utilized a simple combination of polystyrene sulfonate sodium (PSS) and filter paper (FP) to prepare cellulose materials coated with conductive polymers, developing an electrochemical sensor based on the modified materials. The mechanical and electrochemical properties of the fabricated PSS/FP membrane were optimized by adjusting the feeding dosage of PSS. The realized PSS/FP composite containing 7% PSS displayed good conductivity (9.1 × 10-2 S/m), reducing electric resistance by 99.2% compared with the original FP membrane (6.7 × 10-4 S/m). The stable current of the membrane in simulated sweat under different pH environments is highly correlated with the pH values. Additionally, when the membrane is exposed to simulated sweat with varying ion concentrations, the current signal changes in real time with the concentration variations. The response time averages around 0.3 s.

Interface-Stabilized Fiber Sensor for Real-Time Monitoring of Amniotic Fluid During Pregnancy

Diseases in pregnancy endanger millions of fetuses worldwide every year. The onset of these diseases can be early warned by the dynamic abnormalities of biochemicals in amniotic fluid, thus requiring real-time monitoring. However, when continuously penetrated by detection devices, the amnion is prone to loss of robustness and rupture, which is difficult to regenerate. Here, an interface-stabilized fiber sensor is presented for real-time monitoring of biochemical dynamics in amniotic fluid during pregnancy. The sensor is seamlessly integrated into the amnion through tissue adhesion, amniotic regeneration, and uniform stress distribution, posing no risk to the amniotic fluid environment. The sensor demonstrates a response performance of less than 0.3% fluctuation under complex dynamic conditions and an accuracy of more than 98% from the second to the third trimester. By applying it to early warning of diseases such as intrauterine hypoxia, intrauterine infection, and fetal growth restriction, fetal survival increases to 95% with timely intervention.

Elevated blood pressure among children born to women with obstructed labour in Eastern Uganda: a cohort study

BACKGROUND

Globally, high systolic blood pressure accounts for 10.8 million deaths annually. The deaths are disproportionately higher among black people. The reasons for this disparity are poorly understood, but could include a high burden of perinatal insults such as birth asphyxia. Therefore, we aimed to assess the incidence of elevated blood pressure and to explore associated factors among children born to women with obstructed labour.

METHODS

We followed up children born to women with obstructed labour aged 25 to 44 months at Mbale regional referral hospital that had participated in the sodium bicarbonate trial ( Trial registration number PACTR201805003364421) between October 2021 and April 2022. Our primary outcome was elevated blood pressure defined as blood pressure (either systolic or diastolic or both) ≥ the 90th percentile for age, height, and sex in the reference population based on the clinical practice guideline for screening and management of high blood pressure in children and adolescents. We used logistic regression to estimate odds ratios between selected exposures and elevated blood pressure.

RESULTS

The incidence of elevated blood pressure was (39/140, 27.9%: 95% (CI: 20.6-36.1)). Participants aged three years and above had twice the odds of elevated blood pressure as those aged less than three years (Adjusted odds ratio (AOR) 2.46: 95% CI (1.01-5.97). Female participants had 2.81 times the odds of elevated blood pressure as their male counterparts (AOR 2.81 95% CI (1.16-6.82). Participants with reduced estimated glomerular filtration rate had 2.85 times the odds of having elevated blood pressure as those with normal estimated glomerular filtration rate (AOR 2.85 95% CI (1.00-8.13). We found no association between arterial cord lactate, stunting, wealth index, exclusive breastfeeding, food diversity and elevated blood pressure.

CONCLUSION

Our findings show a high incidence of elevated blood pressure among children. We encourage routine checking for elevated blood pressure in the pediatric population particularly those with known risk factors.

Metabolomics profiling of maternal and umbilical cord blood in normoglycemia macrosomia

Background: Macrosomia is a common disorder that occurs during pregnancy. We investigated the comprehensive metabolite profiles of pregnant maternal and fetal sera in normoglycemic macrosomia in a Chinese population. Methods: Forty pregnant women and their fetuses were included in the study (twenty macrosomia patients and twenty normal-weight controls). Maternal and umbilical cord serum metabolites were identified using ultra-performance liquid chromatography coupled with tandem mass spectrometry. Results: In total, 203 metabolites were identified. Lipids and lipid-like molecules were the predominant metabolites. Fifty-three metabolites with significant differences were obtained in the maternal samples. In the macrosomia group, the levels of docosahexaenoic acid, eicosapentaenoic acid, and arachidonic acid were significantly higher than those in the control group. Umbilical cord serum samples were obtained for 24 different metabolites. The maternal-fetal gradient of polyunsaturated fatty acids was decreased in the macrosomia group. Aconitic acid, citric acid, isocitric acid, 2-methylhexanoic acid, and 12-hydroxystearic acid were the common differential metabolites in the maternal and umbilical cord serum samples. Conclusion: There were obvious metabolic abnormalities in the sera of pregnant women and fetuses with macrosomia. Lipids and lipid-like molecules were the predominant differential metabolites but had different classifications in the maternal and umbilical cord serum. These results may provide new insights into the long-term metabolic disorders associated with macrosomia.

Maternal obesity-associated disruption of polarized lactate transporter MCT4 expression in human placenta

Maternal obesity is associated with an increased risk of adverse pregnancy outcomes including stillbirth, and their etiology is thought to be related to placental and fetal hypoxia. In this study, we sought to investigate the levels of lactate in maternal and umbilical cord blood, a well characterized biomarker for hypoxia, and expression of plasma membrane lactate transporter MCT1 and MCT4 in the placental syncytiotrophoblast (STB), which are responsible for lactate uptake and extrusion, respectively, from pregnant women with a diagnosis of obesity following a Cesarean delivery at term. With use of approaches including immunofluorescence staining, Western blot, RT-qPCR and ELISA, our results revealed that in controls the expression of MCT1 was equally observed between basal (fetal-facing, BM) and microvillous (maternal-facing, MVM) membrane of the STB, whereas MCT4 was predominantly expressed in the MVM but barely detected in the BM. However, obese patients demonstrated significant decreased MCT4 abundance in the MVM coupled with concurrent elevated expression in the BM. We also found a linear trend toward decreasing MCT4 expression ratio of MVM to BM with increasing maternal pre-pregnancy BMI. Furthermore, our data showed that the lactate ratios of fetal cord arterial to maternal blood were remarkably reduced in obese samples compared to their normal counterparts. Collectively, these results suggest that the loss of polarization of lactate transporter MCT4 expression in placental STB leading to disruption of unidirectional lactate transport from the fetal to the maternal compartment may constitute part of mechanisms linking maternal obesity and pathogenesis of stillbirth.

Blood gas measures as predictors for neonatal encephalopathy severity

OBJECTIVE

To correlate arterial umbilical cord gas (aUCG) and infant blood gas with severity of neurological injury.

STUDY DESIGN

Retrospective single-site study of infants evaluated for therapeutic hypothermia. Clinical neurological examination and a validated MRI scoring system were used to assess injury severity.

RESULTS

Sixty-eight infants were included. aUCG base deficit (BD) and lactate correlated with infant blood gas counterparts (r = 0.43 and r = 0.56, respectively). aUCG and infant pH did not correlate. Infant blood gas lactate (R_ADJ² = 0.40), infant BD (R_ADJ² = 0.26), infant pH (R_ADJ² = 0.17), aUCG base deficit (R_ADJ² = 0.08), and aUCG lactate (R_ADJ² = 0.11) were associated with clinical neurological examination severity. aUCG and infant blood gas measures were not correlated with MRI score.

CONCLUSION

Metabolic measures from initial infant blood gases were most associated with the clinical neurological examination severity and can be used to evaluate hypoxic-ischemic cerebral injury risk.

Calcium and lactate in the fetal-to-neonatal transition

OBJECTIVE

To explore the relationship between calcium and lactate in arterial cord blood of healthy term neonates in response to the stress of labor.

METHODS

This was a prospective cohort study of consecutive, vaginal, term births in a community medical center (April 2029 to February 2020). Calcium and lactate were measured in cord blood gas analysis immediately after delivery.

RESULTS

In the arterial cord blood of 480 neonates, calcium levels were 1.5 (1.4; 1.5) mmol/L and lactate levels were 3.8 (2.9; 4.9) mmol/L. Calcium and lactate showed a statistically significant positive correlation (Pearson's correlation, r = 0.15, p = .001). Calcium levels had a significant positive correlation with PaCO₂ and a significant negative correlation with pH, PaO₂, HCO₃^-, and ABE levels. Multivariable analysis models confirmed that calcium levels were associated with HCO₃^-, gestational age, and birth weight, all accounting for 7% of the variability.

CONCLUSION

In healthy term vaginally delivered neonates, it was found that calcium and lactate were strongly correlated, together pointing to a neonatal response to the stress of labor and delivery. Cord blood calcium regulation may have an ancillary role in defining neonatal adaptation to extrauterine life.

Incidence and determinants of perinatal mortality among women with obstructed labour in eastern Uganda: a prospective cohort study

BACKGROUND

In Uganda, the incidence and determinants of perinatal death in obstructed labour are not well documented. We determined the incidence and determinants of perinatal mortality among women with obstructed labour in Eastern Uganda.

METHODS

Between July 2018 and September 2019, 584 with obstructed labour were recruited and followed up to the 7th day postnatal. Information on maternal characteristics, obstetric factors and laboratory parameters was collected. Each patient received the standard perioperative care. We used a generalized linear model for the Poisson family, with a log link and robust variance estimation to determine the association between the exposure variables and perinatal death.

RESULTS

Of the 623 women diagnosed with obstructed labour, 584 met the eligibility criteria. There were 24 fresh still births (FSB) and 32 early neonatal deaths (ENND) giving an FSB rate of 43.8 (95% CI 28.3-64.4) deaths per 1000 total births; early neonatal death rate of 58.4 (95% CI 40.3-81.4) deaths per 1000 and an overall perinatal mortality rate of 102.2 (95% CI 79.4-130.6) deaths in the first 7 days of life. A mother being referred in active labour adjusted risk ratio of 2.84 (95% CI: 1.35-5.96) and having high blood lactate levels at recruitment adjusted risk ratio 2.71 (95% CI: 1.26-4.24) were the determinants of perinatal deaths.

CONCLUSIONS

The incidence of perinatal death was four times the regional and national average. Babies to women referred in active labour and those with high maternal blood lactate were more likely to die.

Venous blood gas parameters in healthy Mediterranean buffalo calves in the first 72 hours of life

In the first hours after calving the neonate radically modifies its anatomy and physiology to adapt to extrauterine life. These modifications, however, make the calf prone to respiratory and metabolic dysfunction. Thus, stillbirth, defined as the death of the neonate within 48 h after birth, represents a relevant issue for buffalo farming. Of the clinical procedures, the blood gas analysis of venous samples provides useful information regarding the acid-base status of the neonate, allowing the optimal management of potential illness calves. However, the blood gas parameters have never been studied in the buffalo calf in the first 72 h of life. Thus, this study aimed to report blood gas parameters at calving and 1, 12, 24, and 72 h after birth in healthy buffalo neonates born after normal parturition. The study involved 20 healthy buffalo calves, born from normal pregnancy and parturition. The parturition and the first hours after were monitored by closed-circuit television cameras, and within 1 min after calving the buffalo neonate received a clinical evaluation (APGAR, temperature), venous blood sampling for blood gas (pH, partial pressure carbon dioxide - pCO₂, partial pressure oxygen - pO₂, base excess, bicarbonate concentration, oxygen saturation, total carbon dioxide - tCO₂, and lactate), and glycemia analysis. The same evaluations were performed after 1, 12, 24, and 72 h. The present study showed a moderate mixed acidosis at calving, similar to that reported in the bovine neonate, likely due to the high venous blood pCO₂ and lactate. This acidemia resolved spontaneously within 12 h as a reduction of pCO₂ (P ≤ 0.05). Lactate reduced significantly (P ≤ 0.05) only at 72 h, similarly to the trend reported previously for the bovine calf. Blood lactate concentration was correlated with glycemia at calving and 1 h (r = 0.677, P = 0.014), and with stage 2 duration (r = 0.647, P = 0.006). These findings support a possible mechanism of glucose generation induced by catecholamines coupled to anaerobic metabolism soon after calving. After calving, all the blood gas parameters changed rapidly reaching values comparable with those reported in the literature for older buffalo calves from 72 h after calving. No correlations were found between APGAR score and venous blood gas parameters, likely due to the inclusion criteria that selected only health buffalo calves born after normal parturition. The findings suggested that the venous blood gas analysis could be considered supportive rather than an alternative to the clinical evaluation of the buffalo calf.

Risk factors and complications of small for gestational age

Objective:

The objective of this study was to find out the maternal risk factors and perinatal complications in small for gestational age (SGA) newborns.

Methods:

A total of 181 SGA cases and 1299 cases of appropriate for gestational age (AGA) with the same gestational age between January 2015 and December 2016 were enrolled in Linyi People’s Hospital, China. The risk factors were analyzed and the frequencies of perinatal complications were compared between the two groups.

Results:

The frequencies of maternal risk factors such as pregnancy-induced hypertension, abnormal placenta and twins in the SGA group were significantly higher than that in the AGA group (P<0.05). The incidence of hyperbilirubinemia and hypoglycemia in the perinatal period was also higher in the SGA newborns group (P<0.05), while there were no significant differences in the incidence of pneumonia, apnea, septicemia, intracranial hemorrhage, neonatal asphyxia, congenital malformations, hypoxic-ischemic encephalopathy, respiratory distress syndrome and necrotizing enterocolitis between the two groups.

Conclusions:

SGA can cause perinatal complications including neonatal hypoglycemia and hyperbilirubinemia. It is necessary to strengthen the perinatal monitoring and antenatal care to reduce SGA and the perinatal complications of SGA.

Assessment of lactate production as a response to sustained intrapartum hypoxia in large-for-gestational-age newborns

INTRODUCTION

Lactate concentration in umbilical cord blood is an important measure of intrapartum anaerobic metabolism. The aim of the study was to compare lactate production of large-for-gestational-age (LGA) fetuses against appropriate-for-gestational-age (AGA) fetuses during hypoxia, in diabetic and non-diabetic mothers.

MATERIAL AND METHODS

A total of 17 358 validated paired arterial and venous umbilical cord blood samples taken at birth with a full panel of pH, glucose, and lactate were analyzed relative to LGA (n = 2789) and AGA (n = 14 569). Umbilical cord blood acidemia (pH < mean minus 2 SD) was identified in 518 cases.

RESULTS

Diabetes, but not acidemia, was more common among LGA (5.4%) than AGA cases (2.9%) (respectively P < .0001 and P < .69). At normal pH, glucose was lower in non-diabetes LGA cases, but not in diabetes LGA compared with corresponding AGA cases (respectively P < .0001 and P < .067). Glucose levels were higher in all groups during acidemia (P ≤ .0005), with lower values in non-diabetes LGA but not in diabetes LGA compared with corresponding AGA cases (respectively P = .005 and P < .58). At normal pH, lactate was lower in non-diabetes LGA but not in diabetes LGA compared with corresponding AGA cases (respectively P < .0001 and P < .98); during acidemia, lactate levels were higher in all groups (P < .0001), resulting in no significant difference between LGA and AGA in diabetes as well as in non-diabetes cases (respectively P = .29 and P < .084).

CONCLUSIONS

Considering cord acidemia a proxy for intrapartum hypoxia, LGA fetuses showed no impaired ability to produce lactate during hypoxia. Maternal diabetes did not hamper the ability of LGA fetuses to produce lactate during hypoxia.

The small-for-gestational-age fetus has an intact ability to develop lacticemia when exposed to hypoxia: a retrospective comparative register study

OBJECTIVE

To investigate the ability of small-for-gestational-age (SGA) fetuses to develop lacticemia during hypoxia.

METHODS

Umbilical cord arterial and venous pH, lactate and glucose concentrations were determined in 1777 SGA (<10th percentile) and 14,569 AGA newborns and related to acidemia (pH < mean -2SD). Non-parametric statistics with two-sided p < .05 were considered significant.

RESULTS

Glucose and lactate were linearly related and both variables correlated negatively with pH. Glucose was equal in SGA and AGA at a normal pH, but at severe acidemia it was lower in SGA. Glucose was higher in both groups during acidemia. Lactate was higher in SGA at both a normal and a low pH, and in both groups lactate increased progressively with the severity of acidemia.

CONCLUSIONS

In both SGA and AGA fetuses, glucose was mobilized during acidemia; lactate was higher in SGA at both a normal and low pH. Considering SGA being a proxy for fetal growth restriction, and acidemia a proxy for hypoxia, it is concluded that growth-restricted fetuses have an intact ability to develop lacticemia during hypoxia.

Impact of transient period of metabolic adaptation on perinatal asphyxia in neonates with intrauterine growth retardation

INTRODUCTION

Temperature, glycemia and respiration make neonatal energy triangle (NET). In growth retardation (IUGR) neonates pathological metabolic adaptation exists in transient neonatal period.

AIM

The of this study was to examine the occurrence of pathological NET and check its impact on perinatal asphyxia during the transient period in IUGR neonates.

MATERIAL AND METHODS

One hundred and fifty-nine neonates with IUGR were classified into - early preterm, late preterm and term neonates. By the presence of hypothermia, hypoglycemia and hypoxia in the first hour after birth neonates were classified into: group of pathological NET, group of unstable NET and group of stable NET. We analyzed distribution per body mass, gestational age, type of IUGR, gender and the frequency of perinatal asphyxia between the groups.

RESULTS

The late preterm neonates were the most frequent in the group of pathological NET. Perinatal asphyxia was diagnosed in 52 (32.7%) neonates, with highest frequency in the group of pathological NET. Univariate binary logistic regression analysis showed that pathological NET in neonates with IUGR is significant predictor for perinatal asphyxia occurrence (OR = 8.57; CI = 4.05-18.12; p < 0.001 R² = 0.27).

CONCLUSION

Poor metabolic adaptation in neonates with IUGR in the first hour after birth is significant risk factor for the perinatal asphyxia.

Lactate point-of-care testing for acidosis: Cross-comparison of two devices with routine laboratory results

Objectives

Lactate is a major parameter in medical decision making. During labor, it is an indicator for fetal acidosis and immediate intervention. In the Emergency Department (ED), rapid analysis of lactate/blood gas is crucial for optimal patient care. Our objectives were to cross-compare-for the first time-two point-of-care testing (POCT) lactate devices with routine laboratory results using novel tight precision targets and evaluate different lactate cut-off concentrations to predict metabolic acidosis.

Design and methods

Blood samples from the delivery room (n=66) and from the ED (n=85) were analyzed on two POCT devices, the StatStrip-Lactate (Nova Biomedical) and the iSTAT-1 (CG4+ cassettes, Abbott), and compared to the routine laboratory analyzer (ABL-735, Radiometer). Lactate concentrations were cross-compared between these analyzers.

Results

The StatStrip correlated well with the ABL-735 (R=0.9737) and with the iSTAT-1 (R=0.9774) for lactate in umbilical cord blood. Lactate concentrations in ED samples measured on the iSTAT-1 and ABL-735 showed a correlation coefficient of R=0.9953. Analytical imprecision was excellent for lactate and pH, while for pO₂ and pCO₂ the coefficient of variation was relatively high using the iSTAT-1.

Conclusion

Both POCT devices showed adequate analytical performance to measure lactate. The StatStrip can indicate metabolic acidosis in 1 μl blood and will be implemented at the delivery room.

Lactate in cord blood and its relation to fetal gluconeogenesis in at term deliveries

BACKGROUND

In the human fetus, an increased lactate and glucose level can be anticipated when hypoxia and stress are present and is likely to be a function of both anaerobic metabolism and catecholamine-mediated glycogenolysis/glycolysis.

AIM

We assessed if measurement of lactate in cord artery blood after vaginal and cesarean delivery may predict glucose concentration.

STUDY DESIGN

Umbilical artery cord blood lactacidemia, acidemia, and glucose concentration was tested by 'mini-lab' Radiometer ABL90 FLEX analyzers (Radiometer®, Copenhagen, Denmark) after vaginal delivery (VD), spontaneous (n=493) and by vacuum extractor (n=41) or by cesarean delivery (CD), elective (n=120) and emergency (n=68) in at term, vigorous neonates delivered from March to December 2012 at the 2nd level maternity ward of Policlinico Abano Terme, Abano Terme (Italy).

RESULTS

Cord blood lactacidemia and glucose levels were significantly higher in VD by vacuum extractor than in all other groups (5.32±1.96mmol/L, p=0.050 and 103.6±30.5mg/dL, p<0.001, respectively) and significantly lower in elective CD group (1.77±0.99mmol/L, p<0.001 and 69.8±13.0mg/dL, p<0.001). The cord blood lactate concentration was significantly and positively correlated with glucose levels (r=0.434, p<0.001), but significantly and negatively correlated with pH (r=-0,662, p<0.001), NaHCO3(-) (r=-0,802, p<0.001), and base excess (BE) (r=-0,698, p<0.001). However, in multivariate linear regression analysis, only BE, PaCO2 and cord blood lactate were significant predictive variables (R(2)=0.410; p<0.001) of glucose levels at birth.

CONCLUSION

Cord blood artery lactate and glucose concentration are significantly and positively correlated at birth in healthy, at term vaginally and cesarean delivered neonates, but BE is the best indicator of activated fetal gluconeogenesis.

Flavocytochrome b₂-based enzymatic method of L-lactate assay in food products

L-lactate, a key metabolite of the anaerobic glycolytic pathway, plays an important role as a biomarker in medicine, in the nutritional sector and food quality control. For these reasons, there is a need for very specific, sensitive, and simple analytical methods for the accurate L-lactate measuring. A new highly selective enzymatic method for L-lactate determination based on the use of flavocytochrome b₂ (EC 1.1.2.3; FC b₂) isolated from the recombinant strain of the yeast Hansenula polymorpha has been developed. A proposed enzymatic method exploits an enzymatic oxidation of L-lactate to pyruvate coupled with nitrotetrazolium blue (NTZB) reduction to a colored product, formazan. The maximal absorption peak of the colored product is near λ = 525 nm and the linear range is observed in the interval 0.005–0.14 mM of L-lactate. The main advantages of the proposed method when compared to the LDH-based routine approaches are a higher sensitivity (2.0 μM of L-lactate), simple procedure of analysis, usage of inexpensive, nontoxic reagents, and small amount of the enzyme. Enzymatic oxidation of L-lactate catalyzed by flavocytochrome b₂ and coupled with formazan production from nitrotetrazolium blue was shown to be used for L-lactate assay in food samples. A high correlation between results of the proposed method and reference ones proves the possibility to use flavocytochrome b₂-catalysed reaction for enzymatic measurement of L-lactate in biotechnology and food chemistry.