Associations between long-term averages of metabolic parameters in adulthood and cardiac structure and function in later life

The effects of long-term levels of body mass index (BMI), blood pressure (BP), plasma lipids and fasting blood glucose (FBG) on the cardiac structure and function in later life in general population are to evaluate. We included adult participants without heart failure from Framingham Heart Study. The respective averages over a span of 30-36 years of seven parameters were pooled into linear regression models simultaneously to evaluate their associations with subsequent left atrial internal dimension (LAID), left ventricular mass index (LVMi), internal dimension (LVID), ejection fraction (LVEF), global longitudinal strain (GLS) and mitral inflow velocity to early diastolic mitral annular velocity (E/é). In 1838 participants (56.0% female, mean age 66.1 years), per 1-standard deviation (SD) increment of mean BMI correlated with larger LAID and LVID (β 0.05~0.17, standard error [SE] 0.01 for all), greater LVMi (β [SE], 1.49 [0.46]), worse E/é (β [SE], 0.28 [0.05]). Per 1-SD increment of mean systolic BP correlated with greater LVMi (β [SE], 4.70 [0.69]), LVEF (β [SE], 0.73 [0.24]), E/é (β [SE], 0.52 [0.08]), whereas increase of mean diastolic BP correlated with smaller LVMi (β [SE], -1.61 [0.62]), LVEF (β [SE], -0.46 [0.22]), E/é (β [SE], -0.30 [0.07]). Per 1-SD increment of mean high density lipoprotein cholesterol (HDL-c) correlated with smaller LVID (β [SE], -0.03 [0.01]) and better systolic function (LVEF, β [SE], 0.63 [0.19]; GLS, β [SE], -0.20 [0.10]). The variabilities of BMI, BP and HDL-c also correlated with certain cardiac measurements. In long-term, BMI affected the size and mass of heart chambers, systolic and diastolic BP differently influenced left ventricular mass and function, higher HDL-c linked to better systolic function. Clinical trial registration: URL: https://clinicaltrials.gov . Identifier: NCT00005121.

Prognostic impact of abnormal sodium burden in heart failure patients with preserved ejection fraction

BACKGROUND

Sodium abnormality is common in patients with heart failure (HF) and is associated with adverse clinical outcomes. The aim of this study is to determine the impact of abnormal sodium burden on long-term mortality and hospitalization in HF with preserved ejection fraction (HFpEF).

METHODS

We analysed participants from the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) trial with available baseline and follow-up data (n = 1717). Abnormal sodium burden was defined as the proportion of days with abnormal sodium plasma levels (either <135 mmol/L or > 145 mmol/L). To determine the independent prognostic impact of abnormal sodium burden on the long-term clinical adverse outcomes (The primary outcome was any cause death, the secondary outcomes include cardiovascular disease death, HF hospitalization, any cause hospitalization and the primary endpoint of the original study), a multivariable Cox proportional hazard model and time-updated Cox regression model were performed.

RESULTS

Abnormal sodium burden occurred in 717 patients (41.76%). A high abnormal sodium burden was associated with 1.47 (95% CI, 1.15-1.89) higher risk with any cause mortality, 1.51 (95% CI, 1.08-2.09) higher risk with CVD death and 1.31 (95% CI, 1.02-1.69) higher risk with HF hospitalization when compared with no burden group. When sodium level changes over time were accounted for in time-updated models, abnormal sodium level was still associated with poor clinical outcomes. Diuretic and spironolactone usage did not show a statistical interaction effect on the prognostic significance.

CONCLUSIONS

In HFpEF patients, abnormal sodium burden was an independent predictor long-term any-cause mortality and HF hospitalization.

Association between epicardial adipose tissue and incident heart failure mediating by alteration of natriuretic peptide and myocardial strain

BACKGROUND

Epicardial adipose tissue (EAT) has been suggested to exert deleterious effects on myocardium and cardiovascular disease (CVD) consequence. We evaluated the associations of EAT thickness with adverse outcomes and its potential mediators in the community.

METHODS

Participants without heart failure (HF) who had undergone cardiac magnetic resonance (CMR) to measure EAT thickness over the right ventricular free wall from the Framingham Heart Study were included. The correlation of EAT thickness with 85 circulating biomarkers and cardiometric parameters was assessed in linear regression models. The occurrence of HF, atrial fibrillation, coronary heart disease (CHD), and other adverse events was tracked since CMR was implemented. Their associations with EAT thickness and the mediators were evaluated using Cox regression and causal mediation analysis.

RESULTS

Of 1554 participants, 53.0% were females. Mean age, body mass index, and EAT thickness were 63.3 years, 28.1 kg/m², and 9.8 mm, respectively. After fully adjusting, EAT thickness positively correlated with CRP, LEP, GDF15, MMP8, MMP9, ORM1, ANGPTL3, and SERPINE1 and negatively correlated with N-terminal pro-B-type natriuretic peptide (NT-proBNP), IGFBP1, IGFBP2, AGER, CNTN1, and MCAM. Increasing EAT thickness was associated with smaller left ventricular end-diastolic dimension, thicker left ventricular wall thickness, and worse global longitudinal strain (GLS). During a median follow-up of 12.7 years, 101 incident HF occurred. Per 1-standard deviation increment of EAT thickness was associated with a higher risk of HF (adjusted hazard ratio [HR] 1.43, 95% confidence interval [CI] 1.19-1.72, P < 0.001) and the composite outcome consisting of myocardial infarction, ischemic stroke, HF, and death from CVD (adjusted HR [95% CI], 1.23 [1.07-1.40], P = 0.003). Mediation effect in the association between thicker EAT and higher risk of HF was observed with NT-proBNP (HR [95% CI], 0.95 [0.92-0.98], P = 0.011) and GLS (HR [95% CI], 1.04 [1.01-1.07], P = 0.032).

CONCLUSIONS

EAT thickness was correlated with inflammation and fibrosis-related circulating biomarkers, cardiac concentric change, myocardial strain impairment, incident HF risk, and overall CVD risk. NT-proBNP and GLS might partially mediate the effect of thickened EAT on the risk of HF. EAT could refine the assessment of CVD risk and become a new therapeutic target of cardiometabolic diseases.

TRIAL REGISTRATION

URL: https://clinicaltrials.gov . Identifier: NCT00005121.

Mean corpuscular haemoglobin concentration and outcomes in heart failure with preserved ejection fraction

AIMS

This study aims to evaluate the prognostic value of mean corpuscular haemoglobin concentration (MCHC) on clinical outcomes in patients with heart failure with preserved ejection fraction (HFpEF).

METHODS AND RESULTS

We analysed HFpEF participants from the Americas in the Treatment of Preserved Cardiac Function Heart Failure with an Aldosterone Antagonist (TOPCAT) trial with available baseline data (n = 1747). Patients were grouped into hypochromia or non-hypochromia group according to a MCHC cut-off level of 330 g/L. Cox proportional hazard model was used to explore the prognostic value of hypochromia on the long-term clinical outcomes (the primary endpoint [composite of cardiovascular mortality, HF hospitalization and aborted cardiac arrest], any-cause and HF hospitalization, all-cause and cardiovascular mortality). Patients were further stratified according to baseline estimated glomerular filtration rate (eGFR) to explore the impact of renal dysfunction on the prognostic value of hypochromia. Baseline hypochromia was prevalent (n = 662, 37.9%) and strongly associated with worse clinical outcomes. In patients with worse renal function (eGFR < 60 mL/min per 1.73 m² ), hypochromia was independently associated with primary endpoint (hazard ratio [HR], 1.56; 95% confidence interval [CI], 1.23-1.98; P < 0.001), any-cause hospitalization (HR, 1.43; 95% CI, 1.20-1.71, P < 0.001) and HF hospitalization (HR, 1.40; 95% CI, 1.07-1.84; P = 0.015), whereas no significant association between hypochromia and these outcomes was found in patients with better renal function.

CONCLUSIONS

Among HFpEF patients, hypochromia (i.e. MCHC ≤ 330 g/L) is independently associated with adverse clinical outcomes, especially when in the presence of co-morbidity renal dysfunction.

Phenotypes of heart failure with preserved ejection fraction and effect of spironolactone treatment

Aims

The aims of this study were to explore phenotypes of heart failure with preserved ejection fraction (HFpEF) and evaluate differential effects of spironolactone treatment.

Methods and results

A swap‐stepwise algorithm was used for variable selection. Latent class analysis based on 10 selected variables was employed in a derivative set of 1540 patients from the TOPCAT trial. Cox proportional hazard models were used to evaluate the prognoses and effects of spironolactone treatment. Three phenotypes of HFpEF were identified. Phenotype 1 was the youngest with low burden of co‐morbidities. Phenotype 2 was the oldest with high prevalence of atrial fibrillation, pacemaker implantation, and hypothyroidism. Phenotype 3 was mostly obese and diabetic with high burden of other co‐morbidities. Compared with phenotype 1, phenotypes 2 (hazard ratio [HR]: 1.46; 95% confidence interval [CI]: 1.14–1.89; P = 0.003) and 3 (HR: 2.35; 95% CI: 1.80–3.07; P < 0.001) were associated with higher risks of the primary composite outcome. Spironolactone treatment was associated with a reduced risk of the primary outcome only in phenotype 1 (HR: 0.63; 95% CI: 0.40–0.98; P = 0.042).

Conclusions

Three distinct HFpEF phenotypes were identified. Spironolactone treatment could improve clinical outcome in a phenotype of relatively young patients with low burden of co‐morbidities.

Associations of BMI with mortality in HFpEF patients with concomitant diabetes with insulin versus non-insulin treatment

BACKGROUND

Obesity confers paradoxical survival benefits in heart failure with preserved ejection fraction (HFpEF). The purpose of this study was to examine the impact of DM and insulin treatment status on the associations of body mass index (BMI) with the death risks in HFpEF patients.

METHODS

HFpEF patients from the TOPCAT trial were included. Cox regression model was constructed to assess the relationship of BMI with the risks of all-cause death and cardiovascular death. Restricted cubic splines were used to characterize the dose-response associations of BMI with risks of death.

RESULTS

Compared with normal weight, hazard ratios of all-cause death in overweight and class I obesity were 0.62 (0.45-0.85), 0.67 (0.47-0.94) in no DM HFpEF patients, and 0.48 (0.25-0.91), 0.41 (0.22-0.79) in non-insulin-treated DM patients. However, insulin treatment removed this beneficial effect. Consistent results were found when modeling for time-updated BMI. Cubic spline analyses suggested a linear trend of increased death risk with higher BMI in insulin-treated DM patients.

CONCLUSIONS

The "obesity paradox" was present in HFpEF patients without DM or with non-insulin-treated DM but absent in those with insulin-treated DM. Insulin treatment may be a crucial confounder of the obesity paradox in HFpEF patients.

CLINICAL TRIAL REGISTRATION

URL: https://clinicaltrials.gov. Unique identifier: NCT00094302.

Comparison of two ultrasound contrast agents for left ventricular opacification

Funding Acknowledgements

Type of funding sources: None.

Background

Several ultrasound contrast agents have been approved and used for measurement of LV volumes and ejection fraction (EF). However, there has been no direct comparison between these agents.

Purpose

To compare different imaging parameters between two widely used ultrasound contrast agents for LV opacification when imaged with a low power contrast specific imaging modality

Methods

A retrospective study was performed using recordings of the local echocardiography registry for patients undergoing chemotherapy for cancer treatment.  Patients were included who underwent follow-up echocardiograms (3 months) with 2 different ultrasound contrast agents and had only minor changes in the LV ejection fraction (EF) between the studies (&lt;5%). Qualitative and quantitative analysis of the contrast effect was performed in apical four- and two chamber views (4CV,2CV). For quantitative analysis of the LV opacification square regions of interest (ROI) were placed in the apical and basal regions of the ventricle in each echocardiographic recording and the arithmetic mean and standard deviation of pixel intensity within each ROI was recorded throughout the entire loop. Qualitative visual assessment was performed using a three step visual score in order to assess the endocardial border delineation, basal attenuation and apical swirling. Wilcoxon signed-rank test was used to compare the measurements obtained with different contrast agents.

Results

41 patients fulfilled the inclusion criteria. In all patients suitable recordings for measurement of LV volumes and EF were obtained. The mean + standard deviation of the EF was 61 + 9%. Both contrast agents provided intensive LV opacification in the basal and apical cavities. The video intensities (mean + standard deviation) in the apical and basal cavities were comparable across both contrast agents in the 2CV apical ROI (219.96 + 21.42 vs 224.69 + 20.23, p = 0.32), the 2CV basal ROI (114.55, 42.02 vs 112.79, 42.57, p = 0.81), the 4CV apical ROI (228.02, 17.80 vs 225.51, 20.37, p = 0.30), and the 4CV basal ROI (100.05, 41.11 vs 92.84, 42.54, p = 0.37). Visual assessment of endocardial delineation on end-diastolic and end-systolic frames revealed no statistical difference between the contrast agents.

Conclusion

In patients with normal LV function no clinically relevant differences were found between the two contrast agents regarding LV opacification and endocardial border delineation.

Hispidulin Attenuates Cardiac Hypertrophy by Improving Mitochondrial Dysfunction

Cardiac hypertrophy is a pathophysiological response to harmful stimuli. The continued presence of cardiac hypertrophy will ultimately develop into heart failure. The mitochondrion is the primary organelle of energy production, and its dysfunction plays a crucial role in the progressive development of heart failure from cardiac hypertrophy. Hispidulin, a natural flavonoid, has been substantiated to improve energy metabolism and inhibit oxidative stress. However, how hispidulin regulates cardiac hypertrophy and its underlying mechanism remains unknown. We found that hispidulin significantly inhibited pressure overload-induced cardiac hypertrophy and improved cardiac function in vivo and blocked phenylephrine (PE)-induced cardiomyocyte hypertrophy in vitro. We further proved that hispidulin remarkably improved mitochondrial function, manifested by increased electron transport chain (ETC) subunits expression, elevated ATP production, increased oxygen consumption rates (OCR), normalized mitochondrial morphology, and reduced oxidative stress. Furthermore, we discovered that Sirt1, a well-recognized regulator of mitochondrial function, might be a target of hispidulin, as evidenced by its upregulation after hispidulin treatment. Cotreatment with EX527 (a Sirt1-specific inhibitor) and hispidulin nearly completely abolished the antihypertrophic and protective effects of hispidulin on mitochondrial function, providing further evidence that Sirt1 could be the pivotal downstream effector of hispidulin in regulating cardiac hypertrophy.

MON-536 SPOCK1 Promotes the Progression of Papillary Thyroid Cancer ViaPI3K/Akt Signaling Activation

With the increasing incidence, thyroid cancer as one of the most common malignancy, has got widespread attention during the past few years. Papillary thyroid cancer (PTC) is the most common thyroid cancer type. Understanding the underlining molecular mechanisms of PTC is of great interest. The oncogenic role of SPARC/osteonectin, cwcv, and kazal-like domain proteoglycan 1 (SPOCK1) has been demonstrated in several cancers, however, the clinical and functional significance of SPOCK1 in PTC are largely unknown. Here, we found that the expression of SPOCK1 was upregulated in PTC tissues when comparing with the adjacent normal thyroid tissues. The overexpression of SPOCK1 was associated with the clinicopathological characteristics of the patients with PTC. We demonstrated that the proliferation of PTC cells was significantly promoted and the apoptosis of PTC cells was significantly inhibited in cells with overexpression of SPOCK1. Furthermore, we showed that knockdown of SPOCK1 arrested the cell cycle in G0/G1 phase and promoted the apoptosis in PTC cell lines. Importantly, our data suggested that SPOCK1 promoted the progression of PTC cell via regulating the PI3K/Akt signaling pathway. Taking together, our findings demonstrate that SPOCK1 enhances the activation of PI3K/Akt signaling pathway, thereby promoting the proliferation and inhibiting the apoptosis of PTC cells.

Long Noncoding RNA LOC100129940-N Is Upregulated in Papillary Thyroid Cancer and Promotes the Invasion and Progression

Thyroid cancer is the most common endocrine malignancy, and its incidence has increased rapidly in recent decades worldwide. Papillary thyroid cancer (PTC) is the most common type of all thyroid cancers. The molecular mechanisms underlying the disease still need to be further investigated. Long noncoding RNAs (lncRNAs), a class of noncoding RNAs (ncRNAs) longer than 200 nucleotides, are aberrantly expressed in malignant diseases, including PTC. Here, we identified a novel isoform of LOC100129940 and designated it as LOC100129940-N. We demonstrated that the expression level of LOC100129940-N was elevated in PTC, indicating that LOC100129940-N may be involved in PTC development and progression. Moreover, our results showed that overexpression of LOC100129940-N promoted, whereas silencing of LOC100129940-N suppressed, PTC cell proliferation, invasion, and migration. Mechanistically, LOC100129940-N played an important role in activating Wnt/β-catenin signaling and upregulating downstream target genes. Taken together, we demonstrate that LOC100129940-N promotes the activation of Wnt/β-catenin signaling, which in turn regulates the downstream target genes, thereby enhancing invasion and progression of PTC.

Test characteristics of a level I or II fetal ultrasound in detecting structural heart disease

At the University of California Davis Medical Center, a screening fetal ultrasound examination (level I or II) incorporates a comprehensive segmental evaluation of the fetal heart. This study evaluated the reliability of the fetal ultrasound exam in the detection of abnormal heart anatomy. Our retrospective study reviewed results of 614 antenatal patients that had a screening fetal ultrasound exam. All patients subsequently underwent a detailed targeted fetal cardiac ultrasound exam performed by a pediatric cardiac sonographer and reviewed by a board-certified pediatric cardiologist. Of these 614 patients, 60 fetuses had structural heart disease by the targeted fetal exam. The screening fetal ultrasound exam correctly identified 55 of the 60, with 5 false negatives (8.3% false-negative rate) and 1 false positive (1.7% false-positive rate). Our study suggests that if a screening fetal ultrasound exam incorporates a segmental evaluation of the fetal heart it can reliably detect abnormal heart anatomy. At our institution a targeted fetal cardiac exam is now used to confirm and provide detailed assessment of the heart anatomy when a screening fetal exam is positive for heart disease.

Ethanol inhibits spontaneous activity of central nucleus of the amygdala neurons but does not impair retention in the passive-avoidance task

BACKGROUND

Behavioral studies using pharmacological manipulations that increase neuronal activity of the central nucleus of the amygdala (CeA) have implicated the CeA in enhancement of memory modulation. To date, however, there has been a dearth of studies investigating the effect of a drug that decreases CeA activity on memory modulation-a drug that inhibits the neuronal activity of the CeA might be expected to impair memory modulation. To determine whether ethanol inhibits CeA activity and, if so, whether decreased CeA activity is associated with impairment of memory modulation, this study investigated the effect of ethanol on spontaneous single-unit activity of CeA neurons and retention in the passive-avoidance task.

METHODS

The effect of ethanol (0.35, 0.75, 1.5, 2.5 g/kg) was determined on spontaneously firing neurons in the CeA in urethane-anesthetized rats by use of standard in vivo single-unit electrophysiological recording techniques. Additionally, the effect of ethanol when administered immediately after training in a standard passive-avoidance task was determined on retention the following day.

RESULTS

Ethanol profoundly inhibited spontaneous CeA firing rates in urethane-anesthetized rats at all doses tested. Maximal inhibition was related to dose. Each dose of ethanol significantly inhibited CeA activity within 15 min of administration; within 35 min of administration, 0.75 g/kg of ethanol inhibited CeA activity by 65.2%, and the highest dose (2.5 g/kg) produced nearly complete suppression of CeA activity (81.3%). Although ethanol markedly inhibited CeA activity, these same doses of ethanol failed to impair retention in the passive-avoidance task: 0.35, 0.75, 1.5, and 2.5 g/kg of ethanol, administered immediately after training, failed to alter latency to step-through the following day.

CONCLUSIONS

These results show that ethanol profoundly inhibits spontaneous CeA activity and suggest that inhibition of the CeA is not sufficient to impair retention in the passive-avoidance task.

Structural organization of the rat mitogen-activated protein kinase phosphatase 2 gene

Mitogen-activated protein kinase (MAPK) phosphatases (MKPs) are dual specificity protein phosphatases that specifically inactivate MAPKs. Regulated expression of MKPs plays a key role in determining their physiological function. However, little is known about the molecular mechanism of the activation of MKP genes. In this study, we cloned the rat MKP-2 gene and characterized its structure. The MKP-2 gene has four exons and three introns. The organization of exons of the MKP-2 gene is very similar to that of the MKP-1 gene, suggesting that MKP-1 and MKP-2 are derived from the same ancestral gene. We identified multiple transcription start sites (TSSs) for the MKP-2 gene. There is no functional TATA motif in the 5' proximal region of the TSSs. Instead, this region is highly GC-rich and has two putative Sp1 sites. A 1.8 kb 5' flanking region of the MKP-2 gene is sufficient to mediate transcriptional activation of the luciferase reporter gene by phorbol ester in GH3 cells. These results provide essential information about structural organization and regulatory sequences of the MKP-2 gene for further investigation of the molecular mechanisms of MKP-2 induction by extracellular stimuli.

Stromal-derived factor 1-induced megakaryocyte migration and platelet production is dependent on matrix metalloproteinases

Despite the discovery of thrombopoietin (TPO) and its contribution to megakaryocytopoiesis, the exact mechanisms and sites of platelet production are unknown. It has been shown that mature megakaryocytes (MKs) functionally express the stromal-derived factor 1 (SDF-1) receptor, CXCR4. SDF-1-induced migration of mature MKs through endothelial cell layers results in increased platelet production. Because the migration of polyploid MKs from the bone marrow microenvironment requires remodeling of the perivascular extracellular matrix, it was hypothesized that mature polyploid MKs may express matrix metalloproteinases (MMPs), facilitating their exit into the bone marrow extravascular space. In this report, it is demonstrated that SDF-1 induces the expression and release of gelatinase B (MMP-9) by purified mature polyploid human MKs and an adeno-CXCR4-infected megakaryocytic cell line. Neutralizing antibody to MMP-9, but not MMP-2, blocked SDF-1-induced migration of MKs through reconstituted basement membrane, suggesting that expression of MMP-9 is critical for MK migration. Incubation of mature MKs with a synthetic MMP inhibitor, 5-phenyl-1,10-phenanthrolene, resulted in the inhibition of platelet formation, suggesting that the expression of MMPs is not only critical for megakaryocyte migration but also for subsequent platelet release. Confirming these results, adeno-SDF-1 injection into normal mice resulted in increased platelet counts, a process that could be blocked by a synthetic MMP inhibitor. These results suggest mobilization of MKs involves sequential expression and activation of chemokine receptors such as CXCR4, MMP-9, followed by transendothelial migration. MMP inhibitors may have potential use in the treatment of thrombotic and myeloproliferative disorders. (Blood. 2000;96:4152-4159)

Liposomal mediated transfection of mature rat astrocytes in vitro: a comparison of ten reagents

Ten cationic liposomes were tested for their ability to transfect mature, astrocyte monolayers in vitro using the eucaryotic expression vector plasmid p cytomegalovirus (CMV)-beta. Liposomal agents were examined for optimum length of exposure and optimum cDNA/lipid ratios. Lipofectin demonstrated the highest transfection efficiencies of all agents tested (3.3%). When examined at 3 days following transfection, 24-h exposures yielded higher efficiencies compared to 6 h exposures (1.9%, P=0.07). Although expression appeared to decline by up to 80%, positive cells were still detected up to 2 weeks after transfection with all reagents. Lipofectin represents a useful tool for transfecting mature astrocytes for investigation of gene transfer in vitro.

Autocrine stimulation of VEGFR-2 activates human leukemic cell growth and migration

Emerging data suggest that VEGF receptors are expressed by endothelial cells as well as hematopoietic stem cells. Therefore, we hypothesized that functional VEGF receptors may also be expressed in malignant counterparts of hematopoietic stem cells such as leukemias. We demonstrate that certain leukemias not only produce VEGF but also express functional VEGFR-2 in vivo and in vitro, resulting in the generation of an autocrine loop that may support leukemic cell survival and proliferation. Approximately 50% of freshly isolated leukemias expressed mRNA and protein for VEGFR-2. VEGF(165) induced phosphorylation of VEGFR-2 and increased proliferation of leukemic cells, demonstrating these receptors were functional. VEGF(165) also induced the expression of MMP-9 by leukemic cells and promoted their migration through reconstituted basement membrane. The neutralizing mAb IMC-1C11, specific to human VEGFR-2, inhibited leukemic cell survival in vitro and blocked VEGF(165)-mediated proliferation of leukemic cells and VEGF-induced leukemic cell migration. Xenotransplantation of primary leukemias and leukemic cell lines into immunocompromised nonobese diabetic mice resulted in significant elevation of human, but not murine, VEGF in plasma and death of inoculated mice within 3 weeks. Injection of IMC-1C11 inhibited proliferation of xenotransplanted human leukemias and significantly increased the survival of inoculated mice. Interruption of signaling by VEGFRs, particularly VEGFR-2, may provide a novel strategy for inhibiting leukemic cell proliferation.

Absent pulmonary valve with tricuspid atresia or severe tricuspid stenosis: report of three cases and review of the literature

Absence of the pulmonary valve occurs usually in association with tetralogy of Fallot and occasionally with an atrial septal defect or as an isolated lesion. Very rarely it occurs with tricuspid atresia, intact ventricular septum, and dysplasia of the right ventricular free wall and of the ventricular septum. We present the clinical, anatomic, and histologic findings of a new case, and for the first time, the data from two patients with absent pulmonary valve and severe tricuspid stenosis, who exhibited similar histologic findings. We also reviewed the clinical and anatomic data of 24 previously published cases and compared them with the new cases. In all three new cases, the myocardium of the right ventricle was very abnormal. In the two cases with tricuspid stenosis, large segments of myocardium were replaced with sinusoids and fibrous tissue. In the case with tricuspid atresia, the right ventricular free wall contained only fibroelastic tissue. The ventricular septum in all three patients showed asymmetric hypertrophy and in two of the three patients, multiple sinusoids had replaced large segments of myocardial cells. The left ventricular free wall myocardium and the walls of the great arteries were unremarkable. Our data indicate that myocardial depletion involving the right ventricular free wall and the ventricular septum and its replacement by sinusoids and fibroelastic tissue occur not only in cases of absent pulmonary valve with tricuspid atresia but also in cases of absent pulmonary valve with tricuspid stenosis. The degree of myocardial depletion varies and is more severe when the tricuspid valve is atretic.

Reactivity and assay restriction profiles of monoclonal and polyclonal antibodies to acid phosphatases: a preliminary study

The development of secure diagnostic immunoassays requires, among others, rigorous characterisation of potential antibody reagents. The reactivity profiles of seven antibodies (six monoclonal [MAb] and one polyclonal [PAb]) with putative specificity for tartrate-resistant acid phosphatase (TRAP) and/or osteoclasts were evaluated in enzyme-linked immunosorbent assay (ELISA) and/or immunocytochemistry. MAbs 2H1, 4E6 and 5Cl demonstrated assay restriction: exhibiting reactivity only in ELISA. The remaining three MAbs (G211D, G312G and V35B) and the PAb 8023 recognised recombinant TRAP (rTRAP) in ELISA and native acid phosphatases in selected tissues and cell lines. The latter were cytochemically assessed for both tartrate-sensitive acid phosphatase (TSAP) and TRAP. V35B showed reactivity against the monocytic leukaemia cell line U937 and guinea pig kidney tissue (both TSAP+ and TRAP+) and ECV304 (TSAP+) cells. Interestingly, the reactivity of MAb G211D co-localised with TRAP activity in the membrane of osteoclasts but also detected cytoplasmic components in U937 cells and human embryonic lung fibroblasts (TRAP+ and TRAP+). G211D exhibited immunoreactivity against placental trophoblasts (positive for total AP). Intriguingly, MAbs 2H1, 4E6, 5Cl and PAb 8023 cross-reacted with potato acid phosphatase in ELISA, suggesting reactivity to conformationally similar epitopes. Thus, some of these reagents could be used in the development of standardised diagnostic immunoassays or as drug-targeting agents for conditions in which the pathological process involves bone resorption, the MAbs G211D, 2H1, 4E6, 5Cl and PAb 8023 being useful in ELISA but not immunocytochemical detection of TRAP.

Bisdiamine inhibits extracellular matrix formation and cell proliferation of atrioventricular mesenchyme from developing chick heart valves

Abnormalities of the cushion tissues lead to atrioventricular septal defects (AVSD) and truncus arteriosus (TA). Bisdiamine exposure in the embryo frequently causes AVSD and TA in the newborn chick, mouse, or rat. We studied the effects of bisdiamine on mesenchymal cells grown in aggregate culture isolated from the developing atrioventricular valves of the stage-36 chick embryo. Fibronectin extracellular matrix formation and cell proliferation in the aggregates were assessed in various media. Chick serum stimulated the cells to produce an extracellular matrix and to divide, and the inclusion of bisdiamine inhibited both responses. If we isolated an extracellular matrix from a monolayer of mesenchymal cells and added the sonicated matrix to the medium containing serum and bisdiamine, the matrix incorporated into the aggregates and the cells entered the mitotic cycle. Our previous work established that cells need to attach to an intact extracellular matrix to begin cell division. Thus, we suggest that bisdiamine inhibits the normal formation of the extracellular matrix, leading to reduced cell proliferation, but it does not affect matrix-cell interaction. The lack of cushion growth in situ may be the cause of AVSD or TA.

Comparing a mass-balance algorithm with a Bayesian regression analysis computer program for predicting serum phenytoin concentrations

The ability of a mass-balance algorithm to predict non-steady-state phenytoin concentrations in neurosurgery patients was compared with that of Phenda, a computerized Bayesian regression analysis program. Fifty neurosurgery patients who had had two or more initial phenytoin serum concentrations measured at least 60 hours apart and at least 1 hour after any i.v. doses, with the second concentration being not more than twice and not less than half of the first, and who had had a third or final phenytoin measurement (for use in a prediction analysis) were evaluated. The patients' maximum rates of metabolism were calculated by using the two initial phenytoin concentrations and a mass-balance algorithm, and the third phenytoin concentration was predicted. The patients' demographics and phenytoin dosages and concentrations were entered into Phenda, which was used to predict the third phenytoin concentration. The ability of the two methods to predict the third concentration was evaluated by the method of Sheiner and Beal. Fifty observations from 48 patients were evaluated. The mass-balance algorithm had a positive prediction bias of 2.52 mg/L and a precision error of 5.08 mg/L, compared with 2.30 and 5.30, respectively, for Phenda. The difference in the results between the two methods was not significant. There was no significant difference between the mass-balance algorithm and Phenda in the ability to predict phenytoin concentrations.

Fibroblast growth factor-2 stimulates embryonic cardiac mesenchymal cell proliferation

The proliferation response of stage 36 chick atrioventricular valve mesenchymal cells to fibroblast growth factor-2 (FGF-2) was studied in the tissue-like environment of three-dimensional cell aggregates maintained in organ culture. The mitogenic effects of FGF-2 on mesenchymal tissue depended on the FGF-2-stimulated formation of a fibronectin-containing extracellular matrix. The matrix was absent in unstimulated aggregates, and co-localized with regions of actively proliferating cells in stimulated aggregates. Inhibition of fibronectin matrix formation by the inclusion of Arg-Gly-Asp-containing peptides, which compete with fibronectin for binding to the cell surface alpha 5 beta 1 integrin receptors, abolished the proliferation effects of FGF-2. Inhibition of sulfation of cell surface glycosaminoglycans by treatment with sodium chlorate significantly reduced both the formation of the fibronectin matrix and cell proliferation in response to FGF-2, suggesting an involvement of the low-affinity sulfated glycosaminoglycan FGF receptor system. Thus, the FGF-stimulated growth of embryonic atrioventricular valve mesenchyme in vitro involves the production of a fibronectin matrix. We suggest that the stimulation of the fibronectin matrix represents an essential element in growth factor signaling of mesenchymal tissue, with the matrix serving as an anchorage substratum for the proliferating cells.

Fecal occult blood testing for colorectal cancer in an ethnically diverse population

Fecal occult blood test kits were distributed throughout the ethnically diverse Hawaiian Islands during a 3-week period in 1989. Occult blood was detected in 1,631 persons (11.8%). At least 83% of the participants with positive tests sought medical advice. Subsequently, 76 (4.7%) were diagnosed as having colorectal adenomas and an additional 1.4% had malignant neoplasms (3 gastric and 20 colorectal adenocarcinomas). Three quarters of the colorectal cancers were localized and node-negative. Participation in this program and the type of diagnostic studies done on participants with positive tests varied according to sex and ethnicity. Therefore, these demographic variables must be considered in designing fecal occult blood screening programs.

Cardiomyopathy induced by phenylpropanolamine

A 14-year-old girl had evidence of an acute cardiomyopathy after a minimal overdose of phenylpropanolamine. She had myocardial dysfunction, ventricular dysrhythmia, and secondary pulmonary edema without any associated systemic hypertension. The cardiomyopathy resolved after several days.

Fibroblast behavior in the embryonic chick heart

Intracardiac fibroblasts (mesenchymal cells) of Hamburger and Hamilton stage 36 chick heart reside in the epicardium and atrioventricular valves. The characteristics of the epicardial fibroblasts include segregation from the myocytes of the heart wall myocardium, voluminous extracellular matrix production, and some cell proliferation activity. The atrioventricular fibroblasts intermingle with myocytes at the mutual border between these tissues, produce smaller amounts of extracellular matrix, and show very active cell proliferation. Is the behavior of each population of fibroblasts predetermined or is each responding in a reversible fashion to local environment? A cell aggregate culture system, which permits 3-dimensional cell-cell and cell-matrix interactions, is used to study the behavior of each isolated population of fibroblasts in vitro. In the presence of serum-free medium, each population produces very little extracellular matrix, has relatively low mitotic activity, and does not segregate from myocytes when the aggregate is composed of randomly intermixed myocytes and fibroblasts. In the presence of chicken serum, each population increases matrix production, increases cell proliferation, and sorts from myocytes. Thus, we suggest that the two populations of fibroblasts in the developing heart are responding to local environments and the differences observed in vivo are not the consequence of irreversible states of cellular differentiation.

Fate of the atrioventricular endocardial cushions in the developing chick heart

To determine the fate of the atrioventricular endocardial cushions in cardiac development, we used staining methods for extracellular fibronectin, which is abundant in the endocardial cushions, and actin, which is abundant in the myocytes. White Leghorn chick embryo hearts were harvested at Hamburger and Hamilton stages 26 to 36, and serial sections of the atrioventricular valve region were stained. Before atrioventricular valve formation, fibronectin and actin staining reveal separation between the fibronectin-rich endocardial cushions and the actin-rich myocardial layer. The developing mitral valve leaflets at all of the observed stages contain a fibronectin-rich matrix but no actin-rich myocytes. In contrast, the tricuspid band includes both fibronectin matrix and actin-rich cells. We conclude that the mitral valve leaflets in the chick form predominantly from the endocardial cushion tissue, and the tricuspid band receives contributions from both the endocardial cushions and surrounding myocardium.

Properties of human thymic B cells

B cells, distinct from those seen in myasthenia gravis, are present in normal human thymic medulla, concentrated around the Hassall's corpuscles. We have shown that they constitute 33 +/- 4.8% of the total cells in the thymic medulla. In tissue sections they were often seen to have rosettes of thymocytes around them, a relationship which was maintained when the cells were isolated from the thymus. Thymic B cells expressed cytoplasmic immunoglobulins IgD, IgM and IgG but only rarely IgA. Unlike murine thymic B cells, human thymic B cells were CD5-. Freshly isolated thymic B cells were activated cells, but they rapidly became quiescent and died in culture over a 10-day period unless stimulated with mitogens. Thymic B cells responded to polyclonal B-cell activators SAC and TPA and when stimulated, maintained their relationship with thymocytes. Electron microscopic studies showed that two morphologically different thymocyte populations associated with the B cells. The plasma membranes of larger thymocytes were juxtaposed to the B-cell membrane, but smaller thymocytes with darker cytoplasm were associated with the B cells via cytoplasmic strands. Studies in mice have suggested that B cells are involved in thymic negative selection. The close association between activated B cells and thymocytes observed in this study supports this hypothesis.

Ebstein's anomaly appearing in the neonate. A new surgical approach

Ebstein's anomaly appearing during the neonatal period carries a high mortality rate. These infants exhibit cyanosis, acidosis, and congestive heart failure. The pathophysiologic characteristics consist of severe tricuspid regurgitation and functional pulmonary atresia. As a result of the inability of the right ventricle to generate forward flow through the pulmonary arteries, these infants remain dependent on ductal patency. Since May 1988, five newborn infants with severe Ebstein's anomaly have been admitted for treatment at our institution. At initial examination, they weighed 3.6 +/- 1.8 kg and had a mean oxygen tension of 29.6 +/- 2.3 mm Hg and a mean pH of 7.20 +/- 0.05. Chest roentgenography demonstrated a mean cardiothoracic ratio of 0.81 +/- 0.02. As determined by echocardiography, the right atria were massively enlarged, severe tricuspid regurgitation was present in all patients, and the pulmonary valves were not opening. All infants were dependent on prostaglandin E1 and attempts to wean them from this drug were unsuccessful. Palliative treatment consisted of tricuspid closure with autologous pericardium and an aortopulmonary shunt of 4 mm polytetrafluoroethylene tubing. There were no operative or late deaths. At discharge, mean oxygen tension was 42.2 +/- 0.85 mm Hg and mean systemic oxygen saturation was 83.2% +/- 1.94%. Infants have grown satisfactorily during the follow-up period. Three infants have since returned for further surgical intervention. One infant, at 11 months of age, underwent a Glenn anastomosis for progressive oxygen desaturation. Two infants have returned, at ages 23 and 22 months, for Fontan procedures, which represent their definitive operative management. We believe this new procedure offers excellent palliative treatment for Ebstein's anomaly in critically ill neonates. Feasibility of later definitive correction is demonstrated by the good results obtained with the Fontan procedure in two infants.

Transforming growth factor-beta 1 localized within the heart of the chick embryo

Transforming growth factor-beta 1 is a pleiotropic peptide mediator of growth, differentiation, and extracellular matrix synthesis. In the embryonic chick heart prior to the formation of the endocardial cushions, evidence from in vitro experiments suggests that transforming growth factor-beta 1 may be an inducer of the differentiation of atrioventricular endothelial cells into endocardial cushion mesenchyme. Further in vitro evidence suggests that the factor stimulates mesenchymal cell proliferation, and, thus, growth of the cushions. Using an antibody made against a peptide duplicating the aminoterminal 30 amino acid sequence of transforming growth factor-beta 1, we stained sections of stage 11, 18, 23, 26, and 36 chick hearts by an in situ immunofluorescence technique. Transforming growth factor-beta 1 staining localized to the endocardial surface and epicardial surface of the stage 11 heart, but it decreased from these locations in later stages. The cardiac jelly (stage 11), endocardial cushions (stage 18, 23, and 26), and, subsequently, the heart valve leaflets (stage 36) stained intensely for the growth factor.

Effects of ischemia on epicardial segment shortening

To evaluate the effects of nontransmural ischemia on epicardial contractile function, we implanted sonomicrometers in 15 open-chest, anesthetized (halothane) dogs. One cylindrical crystal (radiating ultrasound 360 degrees) was used as a transmitter for three conventional flat plate crystals arrayed to measure epicardial segment shortening along three different axes that were deviated 0 degree (parallel), 45 degrees (oblique), and 90 degrees (perpendicular) from surface fiber orientation in the anteroapical or posterior-basal left ventricle. During baseline conditions, epicardial shortening was maximal parallel with fiber orientation. Shortening decreased in a non-linear manner as deviation from fiber orientation increased, but there were significant differences between the two left ventricular regions suggesting that more substantial lateral strain occurs in the anterior-apical than the posterior-basal area. During coronary inflow restriction, changes in epicardial segment shortening also varied greatly depending on location and alignment. At levels of wall thickening impairment associated with normal subepicardial perfusion, changes in epicardial function were restricted to the segments aligned perpendicular to fiber orientation whereas the parallel and oblique segments displayed moderate dysfunction or none at all. Thus, transmural tethering modifies epicardial segmental motion during coronary inflow restriction, but the severity of the influence depends on the alignment and location of the epicardial measurements.

Regulation of proliferation of embryonic heart mesenchyme: role of transforming growth factor-beta 1 and the interstitial matrix

Proliferation of atrioventricular cushion mesenchyme of the embryonic avian heart maintained in three-dimensional aggregate culture is stimulated by interaction with the interstitial matrix. Chicken serum or transforming growth factor-beta 1, which stimulates proliferation, induces matrix deposition in regions of the aggregate showing high labeling indices with tritiated thymidine. Dispersed heart mesenchyme interstitial matrix introduced into serum-free culture is incorporated into the aggregate and stimulates cellular proliferation similar to serum or transforming growth factor-beta 1. Proliferation is reversibly inhibited by the peptide Gly-Arg-Gly-Asp-Ser-Pro. It is suggested that transforming growth factor-beta 1 stimulates the production of interstitial matrix and that a sufficient stimulus for proliferation in this system is the presence of the matrix, which acts as the adhesive support for cellular anchorage.

Hereditary long Q-T syndrome presenting as epilepsy: electroencephalography laboratory diagnosis

Patients with hereditary Q-T interval prolongation can present with seizures, syncope, and sudden death. In 2 siblings with autosomal dominant familial long Q-T syndrome, electroencephalographic examinations performed 6 and 2 years before diagnosis included electrocardiographic tracings documenting the cardiac abnormality. A timely diagnosis of this condition may have prevented the death of 1 of these patients. Measurement of the corrected Q-T interval on electrocardiographic tracings obtained in the electroencephalography laboratory should be considered in selected patients.

Subendocardial segment length shortening at lateral margins of ischemic myocardium in dogs

The lateral borders of an infarcted area are sharply delineated in terms of perfusion, but functional impairment extends a limited distance into adjacent nonischemic myocardium. To determine the distribution of functional impairment we arrayed three ultrasonic dimension gauges to measure two subendocardial segment lengths in series. The center crystal, placed at the perfusion boundary (PB) between left anterior descending and circumflex arteries, radiated ultrasound to receiver crystals 7-17 mm to either side of the PB. The locations of the functional measurements relative to the PB were determined with myocardial blood flow (microsphere) "maps" constructed from multiple small tissue samples obtained circumferentially. On the nonischemic side of the PB, segment shortening (dL) increased from 2.00 +/- 0.37 mm during control conditions to 2.20 +/- 0.43 mm (P less than 0.05) after left circumflex coronary occlusion. Similar results were obtained in four conscious chronically instrumented dogs, supporting the conclusion that segment function adjacent to the ischemic margin is well preserved after coronary occlusion. On the ischemic side of the PB, dL decreased from 2.24 +/- 0.54 to 0.42 +/- 0.39 mm (P less than 0.01). By adding the data from the two segments in series, a combined measurement of dL across heterogeneously perfused myocardium was derived that decreased by 38% from control. The level of shortening represented an integral of normal and abnormal motion that was proportional to the mean reduction in blood flow (-44%) in all of the muscle spanned by the crystals. We conclude that subendocardial segment lengths "average" shortening in the muscle they subtend when arrayed across the perfusion boundary.

Paradoxical hypertension after repair of coarctation of the aorta in children: balloon angioplasty versus surgical repair

The incidence and possible causes of paradoxical hypertension were evaluated in eight children who underwent balloon dilatation and seven children who underwent surgical repair of coarctation of the aorta. Both procedures resulted in a significant reduction in the coarctation gradient. Both systolic and diastolic blood pressures increased in the surgical group after repair, whereas systolic pressures decreased and diastolic pressures remained unchanged after balloon angioplasty. In the surgical group, but not in the balloon angioplasty group, plasma catecholamines and plasma renin activity rose during the first 2 days after relief of the coarctation. The data presented in this report support the hypothesis that the sympathetic nervous system and the renin angiotensin system are important mediators of the paradoxical hypertension that occurs after surgical repair of coarctation. Furthermore, balloon angioplasty of coarctation of the aorta does not stimulate either system and thus paradoxical hypertension is not a complication of this procedure.

Direct measurement of inner and outer wall thickening dynamics with epicardial echocardiography

Simple geometric models of the left ventricle and indirect experimental measurements suggest that the inner myocardial wall contributes the largest fraction to total wall thickening. We measured transmural differences in regional wall thickening directly, using an epicardial M mode echocardiographic transducer (6 mm diameter, 5 MHz) placed on the anterior free wall of the left ventricle. Wall thickness was partitioned into inner and outer regions by inserting a waxed, 3-0 suture at different depths within the wall. The suture was used as an intramural echo target that was imaged simultaneously with the endocardium to determine inner and outer fractional contribution to total wall thickness. Data were collected in open-chest dogs at rest, during inotropic stimulation with isoproterenol, and during right heart bypass, which was used to vary cardiac output and preload. Results obtained with this method demonstrated that systolic wall thickness was nonuniform at rest and during each intervention. The fractional contributions to total wall thickening of the inner, middle, and outer thirds of the myocardial wall were estimated from the data to be 58%, 25%, and 17%, respectively. The experimental findings corresponded closely to theoretical predictions, supporting the conclusion that a gradient of thickening exists across the myocardial wall, with the inner portion of the wall contributing the largest fraction to total systolic thickening.

The distribution of functional impairment across the lateral border of acutely ischemic myocardium

To evaluate the degree and lateral extent of dysfunction in nonischemic myocardium adjacent to ischemic muscle, we measured systolic wall thickening with sonomicrometers during circumflex coronary occlusion in 12 anesthetized, open-chest dogs. The locations of the wall thickness measurements relative to the perfusion boundary were determined with myocardial blood flow (microspheres) maps constructed from multiple, small tissue samples. Five minutes after circumflex occlusion, systolic wall thickening in the central ischemic zone decreased from 3.00 +/- 0.61 (mean +/- SD) mm to -0.61 +/- 0.36 mm (P less than 0.01). In nonischemic myocardium greater than 10 mm from the perfusion boundary, systolic wall thickening increased from 2.56 +/- 0.57 to 3.24 +/- 0.72 mm (P less than 0.01). In nonischemic myocardium within 10 mm of the perfusion boundary, systolic wall thickening was slightly but significantly reduced compared with control (2.72 +/- 0.80 to 2.44 +/- 0.79 mm, P less than 0.05), supporting the concept of regional dysfunction in nonischemic myocardium at the lateral borders of an ischemic area. Sigmoid curves were fitted to the data to model changes in wall thickening as a continuous function of distance from the perfusion boundary. This allowed estimation of the extent of dysfunction into nonischemic myocardium which averaged less than 8 mm (approximately 30 degrees of endocardial circumference) at one border. The level of functional impairment in this zone was relatively modest, and systolic wall thickening in the immediate border area was reduced more than 50% from control only in tissue characterized by a blood supply of mixed ischemic and nonischemic origin. We conclude that a functional border zone exists lateral to an acutely ischemic area, but measurement of regional function produces relatively small exaggeration of the size of the acutely ischemic zone if severe reduction in mechanical performance is used to define the extent of the ischemic area.

Dissociation between epicardial and transmural function during acute myocardial ischemia

The relationship between epicardial and transmural function (measured with sonomicrometers) was examined in 13 anesthetized open-chest dogs. Systolic wall thickening was used as a standard of integrated transmural function to compare with epicardial function measured as segment shortening parallel to surface fibers. Three levels of coronary inflow restriction were produced by using decrements in systolic wall thickening as an index of changes in the transmural distribution of myocardial blood flow (microspheres) in myocardium perfused by the left anterior descending artery (anterior-apical group, n = 7) or circumflex artery (posterior-basal group, n = 6). Levels 1 and 2 were characterized by reductions in systolic wall thickening of 35% and 80%, respectively, and marked decreases in deep myocardial blood flow. In the subepicardium, myocardial blood flow was minimally affected at levels 1 and 2 and there was no change in posterior-basal epicardial segment shortening, but anterior segment shortening decreased significantly (by 21% and 37%, respectively). At level 3 myocardial blood flow was reduced transmurally, producing systolic wall thinning and marked epicardial dysfunction in both groups. Parallel epicardial segment shortening underestimated the extent of transmural dysfunction in both groups at levels 1 and 2 but the degree of underestimation was greatest in the posterior-basal group. Anterior-apical segment shortening was impaired at levels 1 and 2, whereas posterior-basal segment shortening was unaffected, suggesting that significant regional variability exists in the epicardial response to nontransmural ischemia.

Body temperature and 5-hydroxytryptamine during early postnatal maturation in mice

A relationship between the maturational increases in body temperature and brain indoleamines has been explored through altering brain 5-hydroxytryptamine (5-HT) content. Effects on body temperature at approximately constant ambient temperature (about 24 degrees C) have been studied following pharmacological manipulations in mice up to 16 days postpartum. Administration of 5-hydroxytryptophan (5-HTP) to increase 5-HT levels was associated with decreased body temperature throughout the maturational period. Depletion of 5-HT with p-chlorophenylalanine (p-CPA) was associated with increased body temperature at all ages studied, although 5-HT depletion was less effective in young animals than in older animals. The drug NSD-1034 acts at a different enzymatic step, and is effective in both central and peripheral tissues to reduce 5-HT and norepinephrine (NE) levels. NSD-1034 decreased body temperature up to 10 days of age; however, the effect was reversed at about 14 days, and the drug increased body temperature significantly in 16-day-old animals. These results suggest a role for 5-HT in the mechanisms of heat production in early postnatal life.