A new approach regarding the treatment of preeclampsia and preterm labor

Aminopeptidases in Cardiovascular and Renal Function. Role as Predictive Renal Injury Biomarkers

Aminopeptidases (APs) are metalloenzymes that hydrolyze peptides and polypeptides by scission of the N-terminus amino acid and that also participate in the intracellular final digestion of proteins. APs play an important role in protein maturation, signal transduction, and cell-cycle control, among other processes. These enzymes are especially relevant in the control of cardiovascular and renal functions. APs participate in the regulation of the systemic and local renin-angiotensin system and also modulate the activity of neuropeptides, kinins, immunomodulatory peptides, and cytokines, even contributing to cholesterol uptake and angiogenesis. This review focuses on the role of four key APs, aspartyl-, alanyl-, glutamyl-, and leucyl-cystinyl-aminopeptidases, in the control of blood pressure (BP) and renal function and on their association with different cardiovascular and renal diseases. In this context, the effects of AP inhibitors are analyzed as therapeutic tools for BP control and renal diseases. Their role as urinary biomarkers of renal injury is also explored. The enzymatic activities of urinary APs, which act as hydrolyzing peptides on the luminal surface of the renal tubule, have emerged as early predictive renal injury biomarkers in both acute and chronic renal nephropathies, including those induced by nephrotoxic agents, obesity, hypertension, or diabetes. Hence, the analysis of urinary AP appears to be a promising diagnostic and prognostic approach to renal disease in both research and clinical settings.

Comparison of protease and aminopeptidase activities in meconium: A pilot study

The successive accumulation of proteases and aminopeptidases in meconium are important physiological components of the intrauterine environment in which a fetus develops. The aim of the present study was to assess the changes in the activities of these enzymes in meconium of healthy infants, and to investigate whether there were any statistically significant associations between activity of the enzymes of interest and the mode of delivery. The activities of proteases and aminopeptidases were determined in meconium portions (n=110) using the substrates BODIPY FL casein and L-leucine-7-amido-4-methylcoumarin hydrochloride, respectively. Serial meconium samples (2-5 per neonate) were collected from healthy infants born vaginally (n=14), and by a cesarean section (n=16). Protease activity (10⁴ RFU/h) was lower in the first meconium sample compared with the final sample from the same infant (3.99±2.03 vs. 5.76±2.24, respectively, mean ± standard deviation; P=0.004). Conversely, there was no significant difference in aminopeptidase activity (10³ nM/l/h) between consecutive meconium samples (P=0.702). The ratios of the first-meconium sample enzyme activity to the last-meconium sample enzyme activity were lower for proteases compared with aminopeptidases (0.76±0.48 vs. 1.35±1.04, respectively mean ± standard deviation; P=0.014), and sustained in the infants born by a cesarean section (P=0.008). Spearman's correlation coefficient analysis between the first and last meconium samples showed the correlation increased in the infants born vaginally compared with the rest of the infants (proteases, R=0.618 vs. R=0.314; aminopeptidases, R=0.688 vs. R=0.566). Aminopeptidase activity did not exhibit any notable dynamic changes during meconium accumulation in the fetal intestine. In infants born vaginally compared with those born by a cesarean section, the activity of both proteases and aminopeptidases in the first meconium sample showed an improved correlation with the activity of the final meconium sample. This may suggest that in the intrauterine environment, during accumulation of meconium in the digestive tract of the fetus, the activity and/or levels of these enzymes and the substrates they catalyze were more stable in newborns born vaginally compared with infants born by caesarean section.

Maternal-fetal vitamin D receptor polymorphisms significantly associated with preterm birth

PURPOSE

Preterm birth (PTB) is a complex trait with strong genetic background, whose etiology is not fully understood. It was recently suggested that pregnancy duration is affected by fetal genetic variation even more than by the maternal genome. Vitamin D receptor (VDR) is involved in embryonic implantation and fertility. We studied the association between both maternal and neonatal vitamin D receptor (VDR) genetic variation and PTB.

METHODS

Maternal and fetal (umbilical cord) DNA was isolated from Jewish Israeli idiopathic preterm newborns (24-36 weeks, n = 146) and control term newborns (>37 weeks, n = 229). Maternal and fetal VDR polymorphisms (FokI, ApaI, BsmI, TaqI) were analyzed by restriction fragment length polymorphism analysis. Using SPSS analysis to correlate VDR genotypes with phenotypic variation: pregnancy duration, preterm birth and spontaneous miscarriages, adjusted for gravidity, parity and gender of newborn.

RESULTS

Women homozygous to VDR ApaI (AA) genotype had significant twofold increase risk for PTB [OR 1.973, (CI) 1.183-3.289, p = 0.009] compared to heterozygous women. Male newborns had significant (p < 0.05) 1.73-fold increase of PTB. Women with history of previous (≥1) spontaneous miscarriage had a significant increased risk for PTB if their newborn carried either of the VDR BsmI homozygous (BB or bb) genotypes compared to the heterozygous (Bb) genotype [OR 6.857, (CI) 1.273-36.934, p = 0.018 and OR 9.231, (CI) 1.753-48.618, p = 0.008, respectively], or VDR ApaI homozygous (AA or aa) genotype compared to heterozygous (Aa) genotype [OR 4.33, (CI) 1.029-18.257, p = 0.046 and OR 7.2, (CI) 1.34-38.917, p = 0.021, respectively].

CONCLUSIONS

We show association between maternal and fetal VDR genotype variants with PTB.

Excess of Aminopeptidase A in the Brain Elevates Blood Pressure via the Angiotensin II Type 1 and Bradykinin B2 Receptors without Dipsogenic Effect

Aminopeptidase A (APA) cleaves angiotensin (Ang) II, kallidin, and other related peptides. In the brain, it activates the renin angiotensin system and causes hypertension. Limited data are available on the dipsogenic effect of APA and pressor effect of degraded peptides of APA such as bradykinin. Wistar-Kyoto rats received intracerebroventricular (icv) APA in a conscious, unrestrained state after pretreatment with (i) vehicle, (ii) 80 μg of telmisartan, an Ang II type-1 (AT1) receptor blocker, (iii) 800 nmol of amastatin, an aminopeptidase inhibitor, and (iv) 1 nmol of HOE-140, a bradykinin B2 receptor blocker. Icv administration of 400 and 800 ng of APA increased blood pressure by 12.6 ± 3.0 and 19.0 ± 3.1 mmHg, respectively. APA did not evoke drinking behavior. Pressor response to APA was attenuated on pretreatment with telmisartan (vehicle: 22.1 ± 2.2 mmHg versus telmisartan: 10.4 ± 3.2 mmHg). Pressor response to APA was also attenuated with amastatin and HOE-140 (vehicle: 26.5 ± 1.1 mmHg, amastatin: 14.4 ± 4.2 mmHg, HOE-140: 16.4 ± 2.2 mmHg). In conclusion, APA increase in the brain evokes a pressor response via enzymatic activity without dipsogenic effect. AT1 receptors and B2 receptors in the brain may contribute to the APA-induced pressor response.

[Proteolytic activity of fetoplacental complex in norm and pathology]

The activity of angiotensin converting enzyme (ACE), carboxypeptidase N (CPN), and leucine aminopeptidase (LAP) has been investigated in the fetoplacental complex (FPC) in normal and placental insufficiency (FPI). ACE and LAP activities were significantly higher in the placental tissue than in maternal serum and umbilical vein serum. CPN activity was significantly lower in umbilical vein serum as compared to that of women in childbirth. Probably, the studied enzymes are involved in formation of reduced sensitivity of FPC of blood vessels during physiological pregnancy. In cases of placental insufficiency a significant increase of LAP activity was found in the placental tissue and umbilical vein serum. In addition, the pathological course of pregnancy caused a significant increase of CPN activity in serum of pregnant women in comparison to the norm. The obtained data suggest that during FPI proteolytic enzymes participate in the formation of compensatoty-adaptive reactions in the FPC. Results of this study are interesting in context of development of methods for prevention and correction of metabolic disorders in pathologies of pregnancy.

Maternal outcomes of magnesium sulphate and diazepam use in women with severe pre-eclampsia and eclampsia in Ethiopia

Background

Preferred anticonvulsant used to treat and prevent fits in eclampsia currently is magnesium sulphate. Clinical monitoring of tendon reflexes, respiration rate and measuring hourly urine output should be done to ensures safe administration of magnesium sulphate

Objective

This study was conducted to evaluate maternal outcomes of magnesium sulphate and diazepam use in the management of severe pre-eclampsia and eclampsia in Jimma University Specialized Hospital.

Methods

A retrospective hospital based cross-sectional comparative study was conducted using data collection format. Data was collected from the hospital delivery care register and patient chart records of all pregnant women who presented with the diagnosis of severe pre-eclampsia and eclampsia in two years and three months period from January, 2010 to April, 2012. Data analysis was done by SPSS version 16.0. A P-value of <0.05 was considered statistically significant in all tests.

Results

A total of 357 patient charts, 217 from magnesium sulphate and 140 from diazepam treated pregnant women group, were reviewed and analyzed. Three pregnant women from the magnesium sulphate treated group and eleven pregnant women from diazepam treated group had at least one convulsion after taking the drug. Greater proportion of patients in the magnesium sulphate treated group had less than four days postpartum stay as compared to the diazepam treated patients (82.3% versus 66.2%). Seizure occurrence, duration of postpartum hospital stays and birth outcome had a statistically significant association with the type of anticonvulsant used.

Conclusions

Magnesium sulphate is more effective than diazepam in the management of severe pre-eclamptic and eclamptic pregnant women in terms of seizure prevention, shortening postpartum hospital stay and reducing maternal morbidities.

Focus on Brain Angiotensin III and Aminopeptidase A in the Control of Hypertension

The classic renin-angiotensin system (RAS) was initially described as a hormone system designed to mediate cardiovascular and body water regulation. The discovery of a brain RAS composed of the necessary functional components (angiotensinogen, peptidases, angiotensins, and specific receptor proteins) independent of the peripheral system significantly expanded the possible physiological and pharmacological functions of this system. This paper first describes the enzymatic pathways resulting in active angiotensin ligands and their interaction with AT₁, AT₂, and mas receptor subtypes. Recent evidence points to important contributions by brain angiotensin III (AngIII) and aminopeptidases A (APA) and N (APN) in sustaining hypertension. Next, we discuss current approaches to the treatment of hypertension followed by novel strategies that focus on limiting the binding of AngII and AngIII to the AT₁ receptor subtype by influencing the activity of APA and APN. We conclude with thoughts concerning future treatment approaches to controlling hypertension and hypotension.