Development and Application of a Method for Rapid and Simultaneous Determination of Three β-agonists (Clenbuterol, Ractopamine, and Zilpaterol) using Liquid Chromatography-tandem Mass Spectrometry

β-agonists are anabolic compounds that promote fat loss and muscle gain, and their administration to livestock may provide economic benefits by increasing growth rate and feed efficiency. For these reasons, β-agonists are also commonly added to livestock feed as growth promoters. This can introduce a significant risk of secondary human poisoning through intake of contaminated meat. A new method for the simultaneous determination of three β-agonists (clenbuterol, ractopamine, and zilpaterol) was developed in this study and applied to various meat samples. The limits of quantification, derived through a validation test following Codex guidelines, were 0.2 μg/kg for clenbuterol and zilpaterol, and 0.4 μg/kg for ractopamine. The average recoveries for clenbuterol, ractopamine, and zilpaterol ranged from 109.1% to 118.3%, 95.3% to 109.0%, and 94.1% to 120.0%, respectively. The recovery and coefficient of variation (CV) values fell within the acceptable range according to the Codex guidelines. This method reduced the analysis time without decreasing detection efficiency by modifying the pretreatment steps. This method could be utilized to manage the safety of imported meat products from countries where zilpaterol use is still permitted, thereby improving public health and preventing β-agonist poisoning due to secondary contamination.

EEG Source Imaging in Partial Epilepsy in Comparison with Presurgical Evaluation and Magnetoencephalography

Background and Purpose

The aim of this study was to determine the usefulness of three-dimensional (3D) scalp EEG source imaging (ESI) in partial epilepsy in comparison with the results of presurgical evaluation, magnetoencephalography (MEG), and electrocorticography (ECoG).

Methods

The epilepsy syndrome of 27 partial epilepsy patients was determined by presurgical evaluations. EEG recordings were made using 70 scalp electrodes, and the 3D coordinates of the electrodes were digitized. ESI images of individual and averaged spikes were analyzed by Curry software with a boundary element method. MEG and ECoG were performed in 23 and 9 patients, respectively.

Results

ESI and MEG source imaging (MSI) results were well concordant with the results of presurgical evaluations (in 96.3% and 100% cases for ESI and MSI, respectively) at the lobar level. However, there were no spikes in the MEG recordings of three patients. The ESI results were well concordant with MSI results in 90.0% of cases. Compared to ECoG, the ESI results tended to be localized deeper than the cortex, whereas the MSI results were generally localized on the cortical surface. ESI was well concordant with ECoG in 8 of 9 (88.9%) cases, and MSI was also well concordant with ECoG in 4 of 5 (80.0%) cases. The EEG single dipoles in one patient with mesial temporal lobe epilepsy were tightly clustered with the averaged dipole when a 3 Hz high-pass filter was used.

Conclusions

The ESI results were well concordant with the results of the presurgical evaluation, MSI, and ECoG. The ESI analysis was found to be useful for localizing the seizure focus and is recommended for the presurgical evaluation of intractable epilepsy patients.

Synergistic Inhibition of Tumor Necrosis Factor-Alpha-Stimulated Pro-Inflammatory Cytokine Expression in HaCaT Cells by a Combination of Rapamycin and Mycophenolic Acid

Background

Keratinocytes release various pro-inflammatory cytokines, chemokines, and adhesion molecules such as intercellular adhesion molecule 1 (ICAM-1) in response to cytokines such as tumor necrosis factor (TNF)-α and interferon (IFN)-γ. Rapamycin and mycophenolic acid (MPA) have potent immunosuppressive activity because they inhibit lymphocyte proliferation.

Objective

We investigated the effects of rapamycin and MPA on the expression of inflammation-related factors such as ICAM-1 and inducible nitric oxide synthase (iNOS), pro-inflammatory cytokines and chemokines, and related signaling pathways in TNF-α-stimulated HaCaT cells.

Methods

The viability of HaCaT cells treated with rapamycin and MPA was confirmed using MTT assay. The expression of various cytokines such as interleukin (IL)-1β, IL-6, and IL-8; inflammation-related factors such as ICAM-1 and iNOS; and the activation of mitogen activated protein kinase (MAPK) signaling pathways mediated by extracellular signal-related kinases (ERK), p38, and c-Jun N-terminal kinases (JNK) in TNF-α-stimulated HaCaT cells were confirmed using reverse transcription-polymerase chain reaction and western blotting.

Results

Combined treatment of TNF-α-induced HaCaT cells with rapamycin and MPA decreased ICAM-1 and iNOS expression and ERK and p38 activation more than treatment with either drug alone. The most significant decrease was observed with a combination of rapamycin (80 nM) and MPA (20 nM). These results show that co-treatment with these agents has a synergistic anti-inflammatory effect by blocking the activation of the ERK/p38 MAPK signaling pathway and thus suppressing the TNF-α-induced expression of ICAM-1 and iNOS.

Conclusion

The combination of rapamycin and MPA could potentially be used as a therapeutic approach in inflammatory skin diseases.

Naphthazarin enhances ionizing radiation-induced cell cycle arrest and apoptosis in human breast cancer cells

Naphthazarin (Naph, DHNQ, 5,8-dihydroxy-l,4-naphthoquinone) is one of the naturally available 1,4-naphthoquinone derivatives that are well-known for their anti-inflammatory, antioxidant, antibacterial and antitumor cytotoxic effects in cancer cells. Herein, we investigated whether Naph has effects on cell cycle arrest and apoptosis in MCF-7 human breast cancer cells exposed to ionizing radiation (IR). Naph reduced the MCF-7 cell viability in a dose-dependent manner. We also found that Naph and/or IR increased the p53-dependent p21 (CIP/WAF1) promoter activity. Noteworthy, our ChIP assay results showed that Naph and IR combined treatment activated the p21 promoter via inhibition of binding of multi-domain proteins, DNMT1, UHRF1 and HDAC1. Apoptosis and cell cycle analyses demonstrated that Naph and IR combined treatment induced cell cycle arrest and apoptosis in MCF-7 cells. Herein, we showed that Naph treatment enhances IR-induced cell cycle arrest and death in MCF-7 human breast cancer cells through the p53-dependent p21 activation mechanism. These results suggest that Naph might sensitize breast cancer cells to radiotherapy by enhancing the p53-p21 mechanism activity.

First Report of Neocosmospora vasinfecta var. vasinfecta Causing Soybean Stem Rot in South Korea

In September 2010, stem rot symptoms were observed on soybean plants (cv. Daepungkong) growing in a field located at Daegu (35.52° N, 128.35° E), South Korea. The first noticeable symptoms, observed on the top leaves, were difficult to distinguish from those of sudden death syndrome (SDS). However, after splitting the stems of symptomatic plants, typical stem rot symptoms appeared as reddish-brown to dark-brown discoloration of the pith. Stem lesions extended 15 to 20 cm upward from the soil surface. To isolate the causal agent, sections of diseased stems were surface disinfected with 1% sodium hypochlorite, placed on potato dextrose agar (PDA) containing streptomycin sulfate, and incubated at 25°C with a 12-h light regime. Two isolates were obtained (SSLNV17 and SSLNV18). Mycelia were white and floccose. Conidia (4.5 to 11.2 × 2.2 to 3.4 μm) were cylindrical to oblong-ellipsoidal, hyaline, and one-celled. Both isolates produced abundant perithecia after 3 to 4 weeks. Perithecia (205 to 331 mm in diameter) were orange to red, globose and ostiolate, with a short neck (80 to 126 mm in diameter). Unitunicate asci (88.6 to 115.3 × 14.5 to 17.3 mm) were cylindrical to clavate, with a short stalk (6.0 to 9.5 × 5.0 to 6.8 mm), and eight spores. Ascospores (13.3 to 17.5 × 10.7 to 12.7 mm) were uniseriately arranged, globose to oval, one-celled, and hyaline to pale brown, with walls with a rugose ornamentation. These morphological features are consistent with those of Neocosmospora vasinfecta var. vasinfecta (1). The internal transcribed spacer (ITS) region, partial translation elongation factor 1-alpha (EF1-α), and β-tubulin genes of rDNA of the two isolates were sequenced using primers ITS4/ITS5 (GenBank Accession Nos. KF662732 and KF662733), EF1-728F/EF1-986R (KF758839 and KF758840), and Bt2a/Bt2b (KF771004 and KF771005), respectively. Sequences of the ITS region, EF1-α, and β-tubulin genes of both isolates showed 99% similarity with several reported N. vasinfecta strains by BLAST analysis. Both morphological and sequence analyses confirmed that the two isolates were N. vasinfecta var. vasinfecta. Pathogenicity tests of both isolates were performed on 15 three-week-old seedlings of soybean cv. Williams inoculated with a spore suspension containing 1.0 × 10⁶ spores/ml, using stem puncture inoculation procedure under controlled conditions (4). Control plants were inoculated in the same way with sterile water. The results were observed by splitting the stem longitudinally and checking for discoloration of the pith 4 to 5 weeks after inoculation. Reddish-brown to dark-brown discoloration was observed in the stem pith of inoculated plants, with occasional chlorosis of the leaves. Moreover, numerous orange-red perithecia were produced on the inoculated stems. However, no symptoms were visible on control plants. The pathogen was re-isolated from the diseased plants, confirming Koch's postulates. Neocosmospora stem rot of soybean was first discovered in Japan and since then it has been reported in the United States and China (2,3,4). To our knowledge, this is the first record of soybean stem rot caused by N. vasinfecta var. vasinfecta in Korea. Our report indicates that Neocosmospora stem rot is a new threat to soybean production in Korea. References: (1) P. F. Cannon and D. L. Hawksworth. Trans. Br. Mycol. Soc. 82:673, 1984. (2) Y. Gai et al. Plant Dis. 95:1031, 2011. (3) F. A. Gray et al. Plant Dis. 64:321, 1980. (4) D. V. Phillips. Phytopathology 62:612, 1972.

Formal protocol for emergency treatment of ruptured intracranial aneurysms to reduce in-hospital rebleeding and improve clinical outcomes

OBJECT

While the incidence of a recurrent hemorrhage is highest within 24 hours of subarachnoid hemorrhage (SAH) and increases with the severity of the clinical grade, a recurrent hemorrhage can occur anytime after the initial SAH in patients with both good and poor clinical grades. Therefore, the authors adopted a 24-hour-a-day, formal protocol, emergency treatment strategy for patients with ruptured aneurysms to secure the aneurysms as early as possible. The incidences of in-hospital rebleeding and clinical outcomes were investigated and compared with those from previous years when broadly defined early treatment was used (<3 days of SAH).

METHODS

During an 11-year period, a total of 1224 patients with a ruptured aneurysm were managed using a strategy of broadly defined early treatment between 2001 and 2004 (Period B, n=423), a mixture of early or emergency treatment between 2005 and 2007, and a formal emergency treatment protocol between 2008 and 2011 (Period A, n=442). Propensity score matching was used to adjust the differences in age, sex, modified Fisher grade, World Federation of Neurosurgical Societies (WFNS) clinical grade at admission, size and location of a ruptured aneurysm, treatment modality (clip placement vs coil embolization), and time interval from SAH to admission between the two time periods. The matched cases were allotted to Group A (n=280) in Period A and Group B (n=296) in Period B and then compared.

RESULTS

During Period A under the formal emergency treatment protocol strategy, the catheter angiogram, endovascular coiling, and surgical clip placement were started at a median time from admission of 2.0 hours, 2.9 hours, and 3.1 hours, respectively. After propensity score matching, Group A showed a significantly reduced incidence of in-hospital rebleeding (2.1% vs 7.4%, p=0.003) and a higher proportion of patients with a favorable clinical outcome (modified Rankin Scale score 0-3) at 1 month (87.9% vs 79.7%, respectively; p=0.008). In particular, the patients with good WFNS grades in Group A experienced significantly less in-hospital rebleeding (1.7% vs 5.7%, respectively; p=0.018) and better clinical outcomes (1-month mRS score of 0-3: 93.8% vs 87.7%, respectively; p=0.021) than the patients with good WFNS grades in Group B.

CONCLUSIONS

Patients with ruptured aneurysms may benefit from a strategy of emergency application of surgical clip placement or endovascular coiling due to the reduced incidence of recurrent bleeding and improved clinical outcomes.

Thermoelectric characteristics of the p-type (Bi, Sb)2Te3 nanocomposites processed with silicon nanodispersion

The p-type (Bi0.2Sb0.8)2Te3 powders were mechanically alloyed and hot pressed at 500 degrees C for 30 minutes with dispersion of Si nanopowders up to 3 vol%. The thermal conductivity of the (Bi0.2Sb0.8)2Te3 nanocomposite was substantially reduced with dispersion of 0.3-3 vol% Si nanopowders due to the enhanced phonon scattering. The maximum dimensionless figure-of-merit of 1.32 at 75 degrees C was obtained for the (Bi0.2Sb0.8)2Te3 nanocomposite dispersed with 1 vol% Si nanopowders, compared to 1.08 of the specimen without Si nanopowder dispersion.

Spontaneous Pneumomediastinum, Pneumopericardium, and Pneumothorax with Respiratory Failure in a Patient with AIDS and Pneumocystis jirovecii Pneumonia

Spontaneous pneumothorax occurs in up to 35% of patients with Pneumocystis jirovecii pneumonia. However, spontaneous pneumomediastinum and pneumopericardium are uncommon complications in patients infected with human immunodeficiency virus, with no reported incidence rates, even among patients with acquired immunodeficiency syndrome (AIDS) and P. jirovecii pneumonia. We report a case of spontaneous pneumomediastinum, pneumopericardium, and pneumothorax with respiratory failure during treatment of P. jirovecii pneumonia in a patient with AIDS; the P. jirovecii infection was confirmed by performing methenamine silver staining of bronchoalveolar lavage specimens. This case suggests that spontaneous pneumomediastinum and pneumopericardium should be considered in patients with AIDS and P. jirovecii pneumonia.

Nurses' Willingness to Report Near Misses: A Multilevel Analysis of Contributing Factors

Although potential future medical errors can best be prevented through reporting near misses, on-site error reporting is not being achieved to a satisfactory level. We surveyed 489 nurses working in 34 wards at a university hospital in Korea in regard to their understanding of factors related to error reporting. Survey items included willingness to report near misses, defensive silence, leader-member exchange, role clarity, and knowledge-sharing climate. Results indicated that defensive silence in the workplace and unclearly defined roles reduced nurses' willingness to report errors, whereas trust-based leader-member exchange (LMX) increased the intention. Knowledge-sharing climates contributed to increasing nurses' intention to report errors, even among those of a silent disposition and in settings where the quality of LMX between the nurses and head nurse was not high.

Increased risk of acute kidney injury associated with higher infusion rate of mannitol in patients with intracranial hemorrhage

Object

Mannitol, an osmotic agent used to decrease intracranial pressure, can cause acute kidney injury (AKI). The objectives of this study were to assess the impact of mannitol on the incidence and severity of AKI and to identify risk factors and outcome for AKI in patients with intracranial hemorrhage (ICH).

Methods

The authors retrospectively evaluated 153 adult patients who received mannitol infusion after ICH between January 2005 and December 2009 in the neurosurgical intensive care unit. Multivariate analysis was used to evaluate the risk factors for AKI after ICH. Based on the odds ratio, weighted scores were assigned to predictors of AKI.

Results

The overall incidence of AKI among study participants was 10.5% (n = 16). Acute kidney injury occurred more frequently in patients who received mannitol infusion at a rate ≥ 1.34 g/kg/day than it did in patients who received mannitol infusion at a rate < 1.34 g/kg/day. A higher mannitol infusion rate was associated with more severe AKI. Independent risk factors for AKI were mannitol infusion rate ≥ 1.34 g/kg/day, age ≥ 70 years, diastolic blood pressure (DBP) ≥ 110 mm Hg, and glomerular filtration rate < 60 ml/min/1.73 m2. The authors developed a risk model for AKI, wherein patients with a higher risk score showed a graded association with a higher incidence of AKI.

Conclusions

The incidence of AKI following mannitol infusion in patients with ICH was 10.5%. A higher mannitol infusion rate was associated with more frequent and more severe AKI. Additionally, age ≥ 70 years, DBP ≥ 110 mm Hg, and established renal dysfunction before starting mannitol therapy were associated with development of AKI.

Polyphenols and antioxidant capacity of a spontaneous reddish mutant in Satsuma mandarin, Shinheungri

A Satsuma mandarin (Citrus unshiu Marc. cv. Miyagawa) spontaneous mutant, Shinheungri, produces fruit with an abnormal red-coloured peel during ripening. The peel and pulp extracts of Shinheungri fruit were evaluated for polyphenolic contents and antioxidant activities by using various in vitro assays. Compared with those of wild type (WT), Shinheungri exhibited slightly higher total flavonoid content and antioxidant activities. The results of UPLC analyses indicate that the peel and pulp extracts of Shinheungri fruit were rich in mainly hesperidin, and they had different flavonoid composition. The present data on Shinheungri revealed a potential source of powerful flavonoids for further detailed phytochemical investigation.

Staufen1-mediated mRNA decay induces Requiem mRNA decay through binding of Staufen1 to the Requiem 3'UTR

Requiem (REQ/DPF2) was originally identified as an apoptosis-inducing protein in mouse myeloid cells and belongs to the novel Krüppel-type zinc finger d4-protein family of proteins, which includes neuro-d4 (DPF1) and cer-d4 (DPF3). Interestingly, when a portion of the REQ messenger ribonucleic acid (mRNA) 3′ untranslated region (3′UTR), referred to as G8, was overexpressed in K562 cells, β-globin expression was induced, suggesting that the 3′UTR of REQ mRNA plays a physiological role. Here, we present evidence that the REQ mRNA 3′UTR, along with its trans-acting factor, Staufen1 (STAU1), is able to reduce the level of REQ mRNA via STAU1-mediated mRNA decay (SMD). By screening a complementary deoxyribonucleic acid (cDNA) expression library with an RNA–ligand binding assay, we identified STAU1 as an interactor of the REQ mRNA 3′UTR. Specifically, we provide evidence that STAU1 binds to putative 30-nucleotide stem–loop-structured RNA sequences within the G8 region, which we term the protein binding site core; this binding triggers the degradation of REQ mRNA and thus regulates translation. Furthermore, we demonstrate that siRNA-mediated silencing of either STAU1 or UPF1 increases the abundance of cellular REQ mRNA and, consequently, the REQ protein, indicating that REQ mRNA is a target of SMD.

The Efficacy of Fimasartan for Cardiovascular Events and Metabolic Syndrome (K-MetS Study): Rationale, Design and Participant Characteristics

Fimasartan, the eighth angiotensin receptor blocker, was launched in March 2011 and was found to have an excellent efficacy and safety profile in a large cross-sectional population study [Safety and Efficacy of Fimasartan in Patients with Arterial Hypertension (Safe-KanArb); Park et al.: Am J Cardiovasc Drugs 2013;13:47-56]. However, there is no long-term study to evaluate its efficacy for major adverse cardiovascular events (MACE) and other effects. The purpose of this study (K-MetS study) was to evaluate whether the early reduction of blood pressure (BP) and/or correction of metabolic derangements with fimasartan will affect MACE and the development of diabetes after long-term use in patients with hypertension. A total of 10,734 patients were screened between October 2011 and October 2012. Of these, 10,601 patients from 582 private clinics and 11 university hospitals were enrolled and are currently treated with fimasartan. The primary endpoints are MACE (cardiovascular mortality, stroke, myocardial infarction, and hospitalization for heart failure) and the development of diabetes after 3 years of follow-up. In addition to BP monitoring in the clinic, home BP monitoring is performed in about two thirds of patients. The patients were 56.2 ± 10.9 years old (mean ± SD), with 48.4% being women. The mean clinic and home systolic/diastolic BP at baseline were 145.0 ± 17.0/88.8 ± 11.4 and 138.6 ± 14.8/82.6 ± 9.9 mm Hg, respectively. The metabolic syndrome was found in 56.4%, increased abdominal circumference in 52.8%, elevated fasting glucose in 46.8%, hypertriglyceridemia in 44.7%, and low high-density lipoprotein cholesterol in 33.3% of patients. Further, complicated hypertension with diabetes occurred in 15.1%, ischemic heart disease in 3.3%, stroke in 0.9%, heart failure in 0.7%, and atrial fibrillation in 0.4% of patients. Most participants in this study had a low-to-moderate risk for hypertension. The K-MetS study is expected to provide valuable information about the effects of early BP control and correction of metabolic abnormalities on future cardiovascular outcomes relative to low-risk hypertension.

Vascular endothelial growth factor-receptor 1 inhibition aggravates diabetic nephropathy through eNOS signaling pathway in db/db mice

The manipulation of vascular endothelial growth factor (VEGF)-receptors (VEGFRs) in diabetic nephropathy is as controversial as issue as ever. It is known to be VEGF-A and VEGFR2 that regulate most of the cellular actions of VEGF in experimental diabetic nephropathy. On the other hand, such factors as VEGF-A, -B and placenta growth factor bind to VEGFR1 with high affinity. Such notion instigated us to investigate on whether selective VEGFR1 inhibition with GNQWFI hexamer aggravates the progression of diabetic nephropathy in db/db mice. While diabetes suppressed VEGFR1, it did increase VEGFR2 expressions in the glomerulus. Db/db mice with VEGFR1 inhibition showed more prominent features with respect to, albuminuria, mesangial matrix expansion, inflammatory cell infiltration and greater numbers of apoptotic cells in the glomerulus, and oxidative stress than that of control db/db mice. All these changes were related to the suppression of diabetes-induced increases in PI3K activity and Akt phosphorylation as well as the aggravation of endothelial dysfunction associated with the inactivation of FoxO3a and eNOS-NOx. In cultured human glomerular endothelial cells (HGECs), high-glucose media with VEGFR1 inhibition induced more apoptotic cells and oxidative stress than did high-glucose media alone, which were associated with the suppression of PI3K-Akt phosphorylation, independently of the activation of AMP-activated protein kinase, and inactivation of FoxO3a and eNOS-NOx pathway. In addition, transfection with VEGFR1 siRNA in HGECs also suppressed PI3K-Akt-eNOS signaling. In conclusion, the specific blockade of VEGFR1 with GNQWFI caused severe renal injury related to profound suppression of the PI3K-Akt, FoxO3a and eNOS-NOx pathway, giving rise to the oxidative stress-induced apoptosis of glomerular cells in type 2 diabetic nephropathy.

Evaluation of Bioactive Components and Antioxidant and Anticancer Properties of Citrus Wastes Generated during Bioethanol Production

In the bioethanol production process employing citrus peels, a large amount of enzymatic hydrolyzed residues is generated as waste material. The bioactive compounds, and antioxidant and anticancer activities of these residues were investigated in the present study. Hydrolyzed citrus residues exhibited similar antioxidant activity as the unhydrolyzed control, which was positively correlated to the contents of total phenols, flavonoids and total carotenoid. Some flavonoids (naringin, naringenin, hesperetin and neohesperidin) and two high value co-products (D-limonene and galacturonic acid) were detected only in hydrolyzed residues. In addition, hydrolyzed residues showed antiproliferative activity and sub-Gl arrest in human melanoma A375 and colon cancer HCT116 cells. These results provide an alternative use for hydrolyzed citrus residues in the functional food, cosmetic and pharmaceutical industries.

A screen for short-range paracrine interactions

Conventional methods for studying paracrine signaling in vitro may not be sensitive to short-range effects resulting from signal dilution or decay. We employ a microfabricated culture substrate to maintain two cell populations in microscale proximity. Individual populations can be quickly retrieved for cell-specific readouts by standard high-throughput assays. We show that this platform is sensitive to short-range interactions that are not detectable by common methods such as conditioned media transfer or porous cell culture inserts, as revealed by gene expression changes in a tumor-stromal crosstalk model. In addition, we are able to detect population-specific gene expression changes that would have been masked in mixed co-cultures. We thus demonstrate a tool for investigating an important class of intercellular communication that may be overlooked in conventional biological studies.

Evaluation of bioactive components and antioxidant and anticancer properties of citrus wastes generated during bioethanol production

In the bioethanol production process employing citrus peels, a large amount of enzymatic hydrolyzed residues is generated as waste material. The bioactive compounds, and antioxidant and anticancer activities of these residues were investigated in the present study. Hydrolyzed citrus residues exhibited similar antioxidant activity as the unhydrolyzed control, which was positively correlated to the contents of total phenols, flavonoids and total carotenoid. Some flavonoids (naringin, naringenin, hesperetin and neohesperidin) and two high value co-products (D-limonene and galacturonic acid) were detected only in hydrolyzed residues. In addition, hydrolyzed residues showed antiproliferative activity and sub-G1 arrest in human melanoma A375 and colon cancer HCT116 cells. These results provide an alternative use for hydrolyzed citrus residues in the functional food, cosmetic and pharmaceutical industries.

Effects of glucocorticoid exposure on growth and structural maturation of the heart of the preterm piglet

Inadequate maintenance of systemic blood flow in neonates following preterm birth is associated with increased morbidity and mortality, and may be due in part to structural immaturity of the myocardium. Maternal glucocorticoid administration is associated with improved cardiovascular function, and possibly promotes structural maturation of the myocardium. This study assessed the structural maturity of the myocardium in male and female preterm and term piglets, and preterm piglets exposed to a regimen of maternal glucocorticoids as used clinically. In preterm, term and glucocorticoid exposed preterm piglets cardiomyocyte maturity was examined by measuring the proportion of binucleated myocytes and the volumes of single living ventricular cardiomyocytes with fluorescence microscopy. Ventricular apoptosis and proliferation were measured by immunohistochemistry. Preterm piglet hearts had fewer binucleated myocytes, smaller myocytes, and more proliferative and fewer apoptotic nuclei than term hearts. Maternal glucocorticoid treatment resulted in increased binucleation with no increase in myocyte volume, and levels of proliferation and apoptosis that were more similar to the term heart. Atrial weights were increased and in female piglets there was an increase in the ratio of left to right ventricular weight. The observed changes in atrial mass and myocyte structural maturation correlated with changes in cardiac function of isolated hearts of littermates. In conclusion, the association between increased myocardial maturation following glucocorticoid exposure, improved cardiac function in littermates, and clinical improvement in human neonatal cardiac function exposed to antenatal glucocorticoids, suggests that glucocorticoid exposure contributes to improved cardiovascular function in preterm infants by promoting myocardial structural maturity.

Expression of adrenoceptor subtypes in preterm piglet heart is different to term heart

Preterm delivery increases the risk of inadequate systemic blood flow and hypotension, and many preterm infants fail to respond to conventional inotrope treatments. If the profile of cardiac adrenoceptor subtypes in the preterm neonate is different to that at term this may contribute to these clinical problems. This study measured mRNA expression of β1, β2, α1A, α2A and α2B-adrenoceptor subtypes by real time PCR in term (113d), preterm (91d) and preterm piglets (91d) exposed to maternal glucocorticoid treatment. Abundance of β-adrenoceptor binding sites in the left ventricle was measured using saturation binding assays. Relative abundance of β1-adrenoceptor mRNA in untreated preterm hearts was ∼50% of term abundance in both left and right ventricles (P<0.001). Trends in receptor binding site density measurements supported this observation (P = 0.07). Glucocorticoid exposure increased β1-adrenoceptor mRNA levels in the right ventricle of preterm hearts (P = 0.008) but did not alter expression in the left ventricle (P>0.1). Relative abundance of α1A-adrenoceptor mRNA was the same in preterm and term piglet hearts (P = >0.1) but was reduced by maternal glucocorticoid treatment (P<0.01); α2A-adrenoceptor mRNA abundance was higher in untreated and glucocorticoid exposed preterm piglet hearts than in term piglets (P<0.001). There was no difference between male and female piglets in mRNA abundance of any of the genes studied. In conclusion, there is reduced mRNA abundance of β1-adrenoceptors in the preterm pig heart. If this lower expression of β-adrenoceptors occurs in human preterm infants, it could explain their poor cardiovascular function and their frequent failure to respond to commonly used inotropes.