Animal models of fetal renal disease

A Simplified Iohexol-Based Method to Measure Renal Function in Sheep Models of Renal Disease

Sheep are highly adequate models for human renal diseases because of their many similarities in the histology and physiology of kidney and pathogenesis of kidney diseases. However, the lack of a simple method to measure glomerular filtration rate (GFR) limits its use as a model of renal diseases. Hence, we aimed to develop a simple method to measure GFR based on the plasma clearance of iohexol by assessing different pharmacokinetic models: (a) CL2: two-compartment (samples from 15 to 420 min; reference method); (b) CL1: one-compartment (samples from 60 to 420 min); (c) CLlf: CL1 adjusted by a correction formula and (d) SM: simplified CL2 (15 to 300 min). Specific statistics of agreement were used to test the models against CL2. The agreement between CL1 and CL2 was low, but both CL1f and SM showed excellent agreement with CL2, as indicated by a total deviation index of ~5–6%, a concordance correlation of 0.98–0.99% and a coverage probability of 99–100%, respectively. Hence, the SM approach is preferable due to a reduced number of samples and shorter duration of the procedure; two points that improve animal management and welfare.

Managing Ureteropelvic Junction Obstruction in the Young Infant

In the last decade, management of congenital UPJ obstruction has become progressively observational despite the lack of precise predictors of outcome. While it is clear that many children will have resolution of their hydronephrosis and healthy kidneys, it is equally clear that there are those in whom renal functional development is at risk. Surgical intervention for the young infant, under 6 months, has become relatively infrequent, yet can be necessary and poses unique challenges. This review will address the clinical evaluation of UPJO in the very young infant and approaches to determining in whom surgical intervention may be preferable, as well as surgical considerations for the small infant. There are some clinical scenarios where the need for intervention is readily apparent, such as the solitary kidney or in child with infection. In others, a careful evaluation and discussion with the family must be undertaken to identify the most appropriate course of care. Further, while minimally invasive pyeloplasty has become commonly performed, it is often withheld from those under 6 months. This review will discuss the key elements of that practice and offer a perspective of where minimally invasive pyeloplasty is of value in the small infant. The modern pediatric urologist must be aware of the various possible clinical situations that may be present with UPJO and feel comfortable in their decision-making and surgical care. Simply delaying an intervention until a child is bigger may not always be the best approach.

Proteomic identification of early changes in the renal cytoskeleton in obstructive uropathy

Bilateral ureteral obstruction (BUO) is associated with renal damage and impaired ability to concentrate urine and is known to induce alterations in an array of kidney proteins. The aim of this study was to identify acute proteomic alterations induced by BUO. Rats were subjected to BUO for 2, 6, or 24 h. Mass spectrometry-based proteomics was performed on the renal inner medulla, and protein changes in the obstructed group were identified. Significant changes were successfully identified for 109 proteins belonging to different biological classes. Interestingly, proteins belonging to the cytoskeleton and proteins related to cytoskeletal regulation were found to be biologically enriched in BUO using online-accessible tools. Western blots confirmed the selected results, demonstrating acute downregulation of proteins belonging to all three cytoskeletal components. The microfilament protein β-actin and the intermediate filament proteins pankeratin and vimentin were all downregulated. β-Tubulin, an important microtubular protein, was found to be significantly downregulated after 24 h. Also, there was significant upregulation of cofilin, an actin-binding protein known to be upregulated in other nephropathy models. Furthermore, both upregulation and downregulation of cytoskeletal motor and regulatory proteins were observed. These findings were confirmed by immunohistochemistry, which clearly showed alterations in labeling in the inner medulla. Interestingly, we were able to confirm selected results in mpkCCD cells exposed to mechanical stretch. Our findings add to the knowledge of BUO-induced acute changes in the renal cytoskeleton and suggest that these molecular changes are partly mediated by increased stretch of the cells during obstruction.

Chronic diseases, chromosomal abnormalities, and congenital malformations as risk factors for respiratory syncytial virus hospitalization: a population-based cohort study

BACKGROUND

Little is known about how chronic conditions other than prematurity, heart disease, and Down syndrome affect the risk and severity of hospitalization for respiratory syncytial virus (RSV). We assess the risk and severity of RSV hospitalization in children with chronic conditions in this register-based, population-based cohort study.

METHODS

Data on RSV tests, maternal smoking, siblings, single parenthood, mode of delivery, gestational age at birth, major surgery, asthma diagnosis, chronic conditions, and hospitalization and discharge dates were obtained from the Danish RSV database, the National Patient and Birth Registries, and the Civil Registration System.

STATISTICS

Cox regression models were used to estimate incidence rate ratios (IRRs) for RSV hospitalization between groups stratified by sex and date of birth. Duration of RSV hospitalization was analyzed in a linear regression and reported as geometric mean ratios.

RESULTS

A total of 391 983 children aged 0-23 months were included in the analysis. A total of 10,616 (2.7%) had a diagnosis for chronic disease. IRRs (95% confidence intervals) for RSV hospitalization in children with any congenital or acquired chronic condition were 2.18 (2.01-2.36) and 2.25 (1.94-2.61), respectively. Several new risk factors for RSV hospitalization, including malformations, interstitial lung disease, neuromuscular disease, liver disease, chromosomal abnormalities, congenital immunodeficiencies, and inborn errors of metabolism, were identified. Duration of RSV hospitalization was increased in many chronic conditions.

CONCLUSIONS

Chronic disease per se is an important risk factor for RSV hospitalization.

Matrilysin (MMP-7) inhibition of BMP-7 induced renal tubular branching morphogenesis suggests a role in the pathogenesis of human renal dysplasia

Congenital renal dysplasia (RD) is a severe form of congenital renal malformation characterized by disruption of normal renal development with cyst formation, reduced or absent nephrons, and impaired renal growth. The authors previously identified that matrilysin (matrix metalloproteinase-7) was overexpressed in a microarray gene expression analysis of human RD compared to normal control kidneys. They now find that active matrilysin gene transcription and protein synthesis occur within dysplastic tubules and epithelial cells lining cysts in human RD by RT-PCR and immunohistochemistry. Similar staining patterns were seen in obstructed kidneys of pouch opossums that show histological features similar to that of human RD. In vitro, matrilysin inhibits formation of branching structures in mIMCD-3 cells stimulated by bone morphogenetic protein-7 (BMP-7) but does not inhibit hepatocyte growth factor-stimulated branching. BMP-7 signaling is essential for normal kidney development, and overexpression of catalytically active matrilysin in human embryonic kidney 293 cells reduces endogenous BMP-7 protein levels and inhibits phosphorylation of BMP-7 SMAD signaling intermediates. These findings suggest that matrilysin expression in RD may be an injury response that disrupts normal nephrogenesis by impairing BMP-7 signaling.

The leucine zipper putative tumor suppressor 2 protein LZTS2 regulates kidney development

Members of the leucine zipper putative tumor suppressor (LZTS) family play crucial roles in transcription modulation and cell cycle control. We previously demonstrated that LZTS2 functions as a novel β-catenin-interacting protein and represses β-catenin-mediated transcription on T-cell factor/lymphoid enhancing factor. Here, we investigate the biological role of LZTS2 using newly established Lzts2 KO mice. Homozygosity for loss-of-function of the Lzts2-targeted allele resulted in severe kidney and urinary tract developmental defects, including renal/ureteral duplication, hydroureter, and hydronephrosis, which were visible prenatally. Altered ureteric bud outgrowth was identified in Lzts2 null embryos. Further analysis indicated that β-catenin subcellular localization was altered in fibroblasts isolated from Lzts2 null embryos. In addition, Wnt growth factor-induced β-catenin-mediated transcriptional activity was increased in Lzts2 null fibroblasts, suggesting a direct role for Lzts2 in the Wnt signaling pathway. These data demonstrate a critical role of LZTS2 in renal development and implicate LZTS2 as a critical regulator of β-catenin-mediated nephrogenesis.

Noninvasive assessment of antenatal hydronephrosis in mice reveals a critical role for Robo2 in maintaining anti-reflux mechanism

Antenatal hydronephrosis and vesicoureteral reflux (VUR) are common renal tract birth defects. We recently showed that disruption of the Robo2 gene is associated with VUR in humans and antenatal hydronephrosis in knockout mice. However, the natural history, causal relationship and developmental origins of these clinical conditions remain largely unclear. Although the hydronephrosis phenotype in Robo2 knockout mice has been attributed to the coexistence of ureteral reflux and obstruction in the same mice, this hypothesis has not been tested experimentally. Here we used noninvasive high-resolution micro-ultrasonography and pathological analysis to follow the progression of antenatal hydronephrosis in individual Robo2-deficient mice from embryo to adulthood. We found that hydronephrosis progressed continuously after birth with no spontaneous resolution. With the use of a microbubble ultrasound contrast agent and ultrasound-guided percutaneous aspiration, we demonstrated that antenatal hydronephrosis in Robo2-deficient mice is caused by high-grade VUR resulting from a dilated and incompetent ureterovesical junction rather than ureteral obstruction. We further documented Robo2 expression around the developing ureterovesical junction and identified early dilatation of ureteral orifice structures as a potential fetal origin of antenatal hydronephrosis and VUR. Our results thus demonstrate that Robo2 is crucial for the formation of a normal ureteral orifice and for the maintenance of an effective anti-reflux mechanism. This study also establishes a reproducible genetic mouse model of progressive antenatal hydronephrosis and primary high-grade VUR.

Congenital ureteropelvic junction obstruction: human disease and animal models

Ureteropelvic junction (UPJ) obstruction is the most frequently observed cause of obstructive nephropathy in children. Neonatal and foetal animal models have been developed that mimic closely what is observed in human disease. The purpose of this review is to discuss how obstructive nephropathy alters kidney histology and function and describe the molecular mechanisms involved in the progression of the lesions, including inflammation, proliferation/apoptosis, renin-angiotensin system activation and fibrosis, based on both human and animal data. Also we propose that during obstructive nephropathy, hydrodynamic modifications are early inducers of the tubular lesions, which are potentially at the origin of the pathology. Finally, an important observation in animal models is that relief of obstruction during kidney development has important effects on renal function later in adult life. A major short-coming is the absence of data on the impact of UPJ obstruction on long-term adult renal function to elucidate whether these animal data are also valid in humans.

Localization of genetic loci controlling hydronephrosis in the Brown Norway rat and its association with hematuria

The aim of this study was to investigate the genetic basis of congenital hydronephrosis (HN), a poorly defined pathological entity, with a rat model. The Brown Norway (BN) strain spontaneously presents a high incidence of apparently asymptomatic HN, whereas the LOU strain does not. A backcross was established between these two strains [BN x (BN x LOU)] and a genomewide scan was performed with 193 microsatellite markers on 121 males and 118 females of this population, which had been phenotyped and scored for HN severity (defined as degree of renal pelvic dilation), followed by linkage analysis with Mapmaker/QTL software. Bilateral HN score was significantly linked to a locus on chromosome 6 (Z scores 4.4 and 4.8 for all rats and for females, respectively). Suggestive loci were identified on chromosomes 2 (for only right-sided HN) and 4. This is the first study in rats to identify genetic loci for HN. Three candidate genes present in these loci were sequenced and insertions detected in Id2 and Agtr1b genes in BN, which did not, however, lead to modified expression as measured by quantitative PCR. Production of a congenic line for part of the chromosome 6 locus confirmed its involvement in HN, but the phenotype was mild. Evidence of hematuria was observed in 9.6% of the backcross rats, mostly males and only in kidneys with HN, but not necessarily in the most severely affected. Hematuria also occurs in the BN colony used here, where it is due to papilloma-like lesions involving pelvic epithelial proliferation, but not in the LOU rat.

pVHL and PTEN tumour suppressor proteins cooperatively suppress kidney cyst formation

In patients with von Hippel-Lindau (VHL) disease, renal cysts and clear cell renal cell carcinoma (ccRCC) arise from renal tubular epithelial cells containing biallelic inactivation of the VHL tumour suppressor gene. However, it is presumed that formation of renal cysts and their conversion to ccRCC involve additional genetic changes at other loci. Here, we show that cystic lesions in the kidneys of patients with VHL disease also demonstrate activation of the phosphatidylinositol-3-kinase (PI3K) pathway. Strikingly, combined conditional inactivation of Vhlh and the Pten tumour suppressor gene, which normally antagonises PI3K signalling, in the mouse kidney, elicits cyst formation after short latency, whereas inactivation of either tumour suppressor gene alone failed to produce such a phenotype. Interestingly, cells lining these cysts frequently lack a primary cilium, a microtubule-based cellular antenna important for suppression of uncontrolled kidney epithelial cell proliferation and cyst formation. Our results support a model in which the PTEN tumour suppressor protein cooperates with pVHL to suppress cyst development in the kidney.

Fetal Sheep Development on Ultrasound and Magnetic Resonance Imaging: A Standard for the in utero Assessment of Models of Congenital Abnormalities

OBJECTIVE

To establish normative data for the size, conspicuity, and imaging characteristics of normal developing fetal sheep organs on ultrasound (US) and magnetic resonance (MR) imaging.

METHODS

US and MR images of ten normal pregnant sheep, at 40, 65, 90, 115, and 140 gestational days (term = 145 days), were scored for organ conspicuity and imaging characteristics. Imaging biometry was correlated with specimens. Gestational age-based growth parameters were modeled using regression.

RESULTS

Imaging biometry showed excellent correlation with specimens. Kidney, bladder, stomach, lung, liver, and spine were seen well from 65 days to term by US. More organs were consistently visible from 90 days to term by MR than by US. Most organ imaging characteristics tended not to change throughout gestation.

CONCLUSION

Normal fetal sheep biometry, organ conspicuity, and imaging characteristics are established for US and MR and have potential use for the in utero assessment of sheep models of congenital abnormalities.

Congenital progressive hydronephrosis (cph) is caused by an S256L mutation in aquaporin-2 that affects its phosphorylation and apical membrane accumulation

Congenital progressive hydronephrosis (cph) is a spontaneous recessive mutation that causes severe hydronephrosis and obstructive nephropathy in affected mice. The mutation has been mapped to the distal end of mouse chromosome 15, but the mutated gene has not been found. Here, we describe the identification of a single base pair change in aquaporin-2 (Aqp2) in cph mutants through genetic linkage mapping. The C-T change led to the substitution of a Ser (S256) by a Leu in the cytoplasmic tail of the Aqp2 protein, preventing its phosphorylation at S256 and the subsequent accumulation of Aqp2 on the apical membrane of the collecting duct principal cells. The interference with normal trafficking of Aqp2 by this mutation resulted in a severe urine concentration defect. cph homozygotes demonstrated polydipsia and produced a copious amount of hypotonic urine. The urine concentration defect could not be corrected by [deamino-Cys1,D-Arg8]-vasopressin (DDAVP, a vasopressin analog), characteristic of nephrogenic diabetes insipidus. The nephrogenic diabetes insipidus symptoms and the absence of developmental defects in the pyeloureteral peristaltic machinery in the mutants before the onset of hydronephrosis suggest that the congenital obstructive nephropathy is most likely a result of the polyuria. This study has revealed the genetic basis for the classical cph mutation and has provided direct genetic evidence that S256 in Aqp2 is indispensable for the apical accumulation, but not the general glycosylation or membrane association, of Aqp2.

Abnormal lung development precedes oligohydramnios in a transgenic murine model of renal dysgenesis

PURPOSE

Renal development regulates prenatal lung growth by maintaining fetal urine output and liquor volume. However, shared signaling pathways underpinning renal and lung morphogenesis indicate that lung hypoplasia in the presence of renal dysgenesis may not result from oligohydramnios alone. We used a transgenic model of renal agenesis/anuria to test whether lung hypoplasia precedes any possible influence of oligohydramnios.

MATERIALS AND METHODS

E12 lung primordia from normal and gamma1III4 deficient murine embryos (fetal anuria and renal agenesis-dysgenesis) were cultured for 72 hours. Morphological lung development was measured at 24, 48 and 78 hours by bud counting and tracings of lung epithelial contour using image analysis software and photomicrographs. Genotyping was performed by a separate blinded investigator.

RESULTS

E12 homozygous mutant lungs branched but had significant decreases in bud count, epithelial area and perimeter compared to heterozygous or WT controls. These changes presented prior to oligohydramnios and persisted in isolation from the developing renal tract throughout the 72-hour culture period.

CONCLUSIONS

Lethal lung hypoplasia seen at term in this model is present from the earliest stages of development, persists in vitro and, therefore, it is not consequent on renal dysfunction. These data implies that 1) fetal interventions for severe prenatal uropathies may have variable success for protecting future lung function and 2) patients with fetal uropathies may warrant greater scrutiny of prenatal lung growth and long-term postnatal lung function.

Obstructive nephropathy: insights from genetically engineered animals

Congenital obstructive nephropathy is the primary cause for end-stage renal disease (ESRD) in children. An increasingly used animal model of obstructive nephropathy is unilateral ureteral obstruction (UUO). This model mimics, in an accelerated manner, the different stages of obstructive nephropathy leading to tubulointerstitial fibrosis: cellular infiltration, tubular proliferation and apoptosis, epithelial-mesenchymal transition (EMT), (myo)fibroblast accumulation, increased extracellular matrix (ECM) deposition, and tubular atrophy. During the last decade genetically modified animals are increasingly used to study the development of obstructive nephropathy. Although the use of these animals (mainly knockouts) has highlighted some pitfalls of this approach (compensation by closely related gene products, absence of temporal knockouts) it has brought important information about the role of specific gene-products in the pathogenesis of obstructive nephropathy. Besides confirming the important pathologic role for angiotensin II (Ang II) and transforming growth factor-beta (TGF-beta) in obstructive nephropathy, these animals have shown the complexity of the development of tubulointerstitial fibrosis involving a large number of closely functionally related molecules. More interestingly, the use of these animals has led to the discovery of unexpected and contradictory roles (both potentially pro- and antifibrotic) for Ang II, for ECM degrading enzymes matrix metalloproteinase 9 (MMP-9) and tissue plasminogen activators (PAs), for plasminogen activator inhibitor 1 (PAI-1), and for the adhesion molecule osteopontin (OPN) in obstructive nephropathy. Further use of these animals, especially in combination with pharmacologic tools, should help to better identify potential antifibrotic strategies in obstructive nephropathy.

Id2 haploinsufficiency in mice leads to congenital hydronephrosis resembling that in humans

Congenital hydronephrosis is one of the most common anomalies found in humans and may cause renal failure in childhood. Half of the cases are due to obstruction at the ureteropelvic junction (UPJ). Here we report that mice lacking Id2, an inhibitor of basic helix-loop-helix (bHLH) transcription factors, exhibit hydronephrosis mimicking the characteristics of human cases such as unilaterality and male preponderance. Hydronephrosis was found even in Id2+/- mice. The penetrance was 67.2% in Id2-/- males, 48.8% in Id2+/- males, 28.0% in Id2-/- females and 20.0% in Id2+/- females. Distortion or high insertion of the ureter at the UPJ was frequently observed and these morphological changes were evident in late embryogenesis. Histologically, the muscle layer, where Id2 is normally expressed, was hypertrophic and/or irregular at the UPJ. Furthermore, gene expression analysis suggested that BMP4 (bone morphogenetic protein 4), which is known to be involved in the development of hydronephrosis, appears to function as an upstream factor of Id2. Our results thus raise the possibility that Id2 is a gene responsible for the pathogenesis of hydronephrosis in man.

Concomitant anomalies in 100 children with unilateral multicystic kidney

OBJECTIVES

To determine the incidence and type of associated urogenital anomalies in children with a unilateral multicystic kidney and to assess in children with nephrectomy the additional diagnostic value of cystoscopy and, in girls, of colposcopy.

METHODS

This was a follow-up study of 100 fetuses with antenatally detected unilateral multicystic kidneys. After ultrasound confirmation of the diagnosis within a few days after birth voiding cystourethrography and isotope scan were performed in 83 of the surviving children to exclude vesicoureteral reflux and to establish renal function. Eighty-one children underwent nephrectomy and, prior to surgery, all underwent cystoscopy and girls also underwent colposcopy.

RESULTS

Seventy-five children had one or more additional urogenital anomalies: 39 had anomalies of the contralateral kidney, 40 had anomalies of the ipsilateral kidney and 30 had one or more anomalies of the lower urogenital tract. With cystoscopy 54 anomalies of the genitourinary tract were detected in 48 children and with colposcopy three anomalies were detected in 35 girls. Eighty-one children had a nephrectomy or heminephrectomy and 33 of them needed other urological intervention. Thirteen fetuses died (mostly from agenesis of the contralateral kidney) and six infants had no surgery at all.

CONCLUSION

Children with a unilateral multicystic kidney are at considerable risk of having other urogenital anomalies. When cystoscopy and colposcopy are added to routine investigations the rate of detection of anomalies is 75%, twice that reported in the literature.

Calcineurin is required in urinary tract mesenchyme for the development of the pyeloureteral peristaltic machinery

Congenital obstructive nephropathy is the principal cause of renal failure in infants and children. The underlying molecular and cellular mechanisms of this disease, however, remain largely undetermined. We generated a mouse model of congenital obstructive nephropathy that resembles ureteropelvic junction obstruction in humans. In these mice, calcineurin function is removed by the selective deletion of Cnb1 in the mesenchyme of the developing urinary tract using the Cre/lox system. This deletion results in reduced proliferation in the smooth muscle cells and other mesenchymal cells in the developing urinary tract. Compromised cell proliferation causes abnormal development of the renal pelvis and ureter, leading to defective pyeloureteral peristalsis, progressive renal obstruction, and, eventually, fatal renal failure. Our study demonstrates that calcineurin is an essential signaling molecule in urinary tract development and is required for normal proliferation of the urinary tract mesenchymal cells in a cell-autonomous manner. These studies also emphasize the importance of functional obstruction, resulting from developmental abnormality, in causing congenital obstructive nephropathy.

Perinatal obstructive nephropathy

Significant advances have been made recently in elucidating the cellular consequences of urinary tract obstruction during renal development. Urinary tract obstruction impairs growth and maturation of the kidney, and can also cause renal maldevelopment. This includes a reduction in the number of nephrons, tubular atrophy, and progressive interstitial fibrosis. Apoptosis (programmed cell death) accounts for much of the loss of tubular epithelial cells. Factors contributing to apoptosis include stretching of cells in dilated tubules, altered renal production of growth factors, and infiltration of the renal interstitium by macrophages. Two major controversies remain regarding the surgical management of congenital obstructive nephropathy: first, which fetuses with bladder outlet obstruction should undergo prenatal intervention, and second, which infants should undergo early pyeloplasty for ureteropelvic junction obstruction? Even after successful surgery for congential obstructive nephropathy, all patients should be followed for hypertension, proteinuria, or renal deterioration.

[Experimental ureteral obstruction and knockout animals]

Obstructive uropathies caused by congenital malformations of the urinary tract are relatively frequent in newborn. These obstructive lesions are the main cause for renal disease in infancy. Most of these uropathies are treated by surgical interventions restoring the drainage function of the urinary tract. Clinically these patients are cured but the question remains wether these patients will develop renal disease in adult life, since it has been recently shown in animal models that transient, neonatal and prenatal, ureteral obstruction induces significant renal deterioration later in life. Except for angiotensin converting enzyme inhibitors that slow down the progression of renal disease, no specific drugs reducing renal fibrosis exist. Animal models of ureteral obstruction have allowed to clearly identify the events leading to tubulointerstitial fibrosis. Furthermore, more recently, the use of ureteral obstruction in genetically engineered animals has shown pro- and anti-fibrotic properties of a large number of molecules. These studies using genetically engineered animals have suggested several new future promising therapeutic directions to treat renal fibrosis.

Purification of bovine IGFBP-3 and the development of an enzyme immunoassay for the protein

Insulin-like growth factor binding protein-3 (IGFBP-3), the most prominent IGF-binding protein in serum, has been demonstrated to modulate the effects of the IGFs but also to exert IGF-independent actions. Quantification of IGFBP-3 in livestock species, in particular ruminants, is commonly limited to blotting methods in spite of the importance of these species. Here we describe the development of a specific homologous enzyme-linked immunosorbent assay (ELISA) to measure bovine IGFBP-3 in bovine plasma, serum and milk. IGFBP-3 purified from bovine serum was used both as standard and also for tracer synthesis. A specific antiserum was raised in rabbits using a synthetic peptide based on the sequence of bovine IGFBP-3. The measuring range of the assay was between 50 and 1000 ng IGFBP-3 per milliliter of plasma or milk. Mean recovery was 97.3% for plasma and 100.1% for milk. Intra- and interassay coefficients of variation were 6.2% and 9.3%, respectively. For the biological verification of the assay, IGFBP-3 was determined in plasma obtained from 12 dairy cows before and after being injected with a depot-formulated growth hormone (GH) preparation. GH, a well-characterized stimulator of IGFBP-3, led to a 1.3-fold increase of basal IGFBP-3 concentrations during days 3 to 19 after the injection. The availability of an ELISA procedure which permits precise and sufficiently sensitive quantification of bovine IGFBP-3 and which can be used on large sample numbers thereby avoiding the need for radioactive labels, should facilitate further research studies.

The effects of chronic ethanol consumption during early pregnancy on conceptus health and uterine function in pigs

BACKGROUND

Maternal ethanol consumption impairs fetal health, but it is unclear if this occurs through direct actions on the conceptus or indirectly through effects on the uterus. The objective of this study was to determine if chronic ethanol consumption in swine would impair early embryonic and fetal health either through direct effects on the conceptus or indirect effects on the endometrium.

METHODS

Four experiments evaluated the effects of chronic ethanol consumption during early pregnancy. Female pigs were fed either 350 ml of 95% ethanol or an isocaloric amount of dextrose at 10 to 14-hr intervals beginning on day 10 after pubertal estrus and continuing until ovariohysterectomy 11 to 35 days after mating. At the second estrus, pigs were mated to a fertile boar that did not consume alcohol.

RESULTS

In experiment 1, ethanol consumption increased (p < 0.01) blood alcohol concentrations that peaked 2-3 hr after feeding. In experiment 2, ethanol was detectable in uterine flushings 2 hr after feeding on day 11 of pregnancy and was highly correlated (r = 0.989, p < 0.001) with blood alcohol concentration. In experiment 3, ethanol consumption did not affect endometrial phospholipase C activity on days 11 and 16 of pregnancy but decreased (p < 0.05) basal endometrial prostaglandin F(2alpha) production on day 16. However, ethanol consumption did not decrease the number of conceptuses on day 11 or conceptus DNA content on days 11 or 16. In experiment 4, ethanol consumption decreased (p < 0.05) fetal survival rate to 58% versus 85% in dextrose-fed controls on day 35 of pregnancy. For viable conceptuses, ethanol consumption reduced (p < 0.01) fetal weight, fetal crown-rump length, placental weight and volume of placental (chorio-allantoic + amniotic) fluid.

CONCLUSION

These results indicate that chronic ethanol consumption may impair conceptus health directly or indirectly through actions upon the endometrium. Thus, the pig may be a valuable experimental model for studies on the effects of maternal alcohol consumption on conceptus development.

Programming the cardiovascular system, kidney and the brain--a review

The concept that 'life before birth' or the 'first environment' is important in determining subsequent risk for the development of cardiovascular/metabolic disease is now gaining acceptance. There are substantial data from animal experiments that complement and enhance the epidemiological data from human studies. We argue that any factor which disrupts nephrogenesis, and lowers nephron number, during the period of active nephrogenesis, will induce malapadaptive changes in the future functioning of that kidney and predispose to the onset of adult hypertension. Such factors include exposure of the mother, to a particular low-protein diet, excess synthetic or natural glucocorticoid at certain critical periods, mild vitamin A deficiency, elevated blood glucose, unilateral nephrectomy during the period of nephrogenesis, as well as the deletion of one allele of a gene (GDNF) involved in normal metanephric development. All of these stresses are associated with a reduction (20-40 per cent) in total nephron number in the adult, and the development of hypertension. In some hypertensive models, (rats) there is evidence of alterations in the components of the hippocampal/hypothalamic/pituitary/adrenal axis, whereas in others (sheep) there are alterations in the expression of angiotensinogen (hypothalamus) and angiotensin II receptor type I (AT(1)) in the medulla oblongata. The surprising finding is that the period when the kidney and brain are most vulnerable is very early in development, when both organs are in an extremely primitive state of development.