Hyperbilirubinemia diminishes respiratory drive in a rat pup model

Although apnea is common in premature babies, there is a paucity of information concerning the pathophysiologic basis of these episodes and their relationship to other perinatal conditions such as hyperbilirubinemia. Unconjugated hyperbilirubinemia in premature infants, even in moderately high levels, may cause encephalopathy affecting brainstem functions and has been linked to increased incidence of apnea in these infants. Thus, there is a need to clarify mechanisms by which bilirubin may alter respiratory control and induce apnea of prematurity. In this study, bilirubin or placebo was infused i.v. in 9-d-old rat pups (n = 36). Serum hyperbilirubinemia peaked in the first hours after bilirubin infusion. Twenty-four hours after bilirubin infusion, respiration was recorded by plethysmography at rest and under hypercapnic and hypoxic conditions. In treated pups, minute ventilation in room air was significantly reduced, hyperventilatory response to CO2 was blunted, and hypoxic ventilatory depression was increased, compared with placebo-injected rat pups. Brainstem bilirubin deposition and immunoreactivity to bilirubin was detected in the brainstem on histologic analysis. We speculate that high serum bilirubin levels may cause prolonged inhibition of brainstem autonomic function and that this could underlie the exacerbation of apnea noted in premature babies who have experienced jaundice.     

Child rearing and positive deviance in the development of preschoolers: a microanalysis

OBJECTIVE: To study the maternal child-rearing behaviors, parental attributes and socio-economic status of the family and to analyze their association with positive deviance in the developmental status of preschool children between 1-5 years of age. DESIGN: Cross-sectional. SETTING: Rural community. METHODS: A total of 260 children and their mothers were evaluated. Weight and height-for-age indices were used to assess growth. ICMR Developmental Screening Test was used to assess psychosocial development. Bhatia's Performance Test was used to assess maternal intelligence. Narayan Rao's Rating Scale was used to assess socio-economic status and a child-rearing interview schedule developed and pretested for the purpose of the study to assess maternal child-rearing practices and behaviors. RESULTS: Stepwise multiple regression with psychosocial development as dependent variable indicated significant associations between specific maternal behavioral categories and psychosocial development of 1-5 year old children. Children, whose mothers were responsive to their needs, were consistent in their interaction with them and were also emotionally stable during specific child rearing situations were those identified as "positive deviants" with regard to their development. Other factors, which were significantly associated with positive deviance in children, were paternal literacy and nuclear type of family. Significant differences were observed between genders. CONCLUSIONS: The data generated from the study could identify the important factors that were associated with "positive deviance" in the development of children. These factors can be useful components for parental counseling in clinical practice and as educational material in community programmes such as the ICDS and self-help groups at the village level.     

Adriamycin mouse model: a variable but reproducible model of tracheo-oesophageal malformations

A spectrum of tracheo-oesophageal malformations is seen in humans: oesophageal atresia, tracheal agenesis and laryngotracheo-oesophageal clefts. They are thought to share a common but unknown aetiology. These birth defects are frequently associated with other VACTERL anomalies. The adriamycin rat model (ARM) has proved to be a valuable model of the VACTERL anomalies, illustrating the dysmorphogenesis of oesophageal atresia and tracheal agenesis. As organogenesis relies on temporaspatially co-ordinated signalling systems, the next step would be to study the molecular pathogenesis of tracheo-oesophageal malformations. However, the mouse is the foremost mammal studied by developmental biologists, offering an expanding wealth of knowledge and scientific research techniques with which to investigate these anomalies. A limited dose response analysis of the teratogenicity of adriamycin in the mouse has identified a dose and timing of injections that produced tracheo-oesophageal malformations and other VACTERL anomalies. A clear account of the types and variability of the tracheo-oesophageal malformations produced by this dose is essential in order to be able to plan and interpret any future investigations of early gestation fetuses. CBA/Ca mice were accurately time-mated (n = 10). Nine dams received intraperitoneal injections of adriamycin (6 mg/kg) and one control dam received saline injections, on days 7 and 8. Fetuses were harvested on day 18, near term. Tracheo-oesophageal malformations were examined by dissecting microscope and serial transverse sections. Results are reported in the standard teratological manner as mean percentage per litter (±SEM). The resorption rate of the adriamycin treated fetuses was 50.4%. There were 29 adriamycin treated fetuses for inspection. Tracheo-oesophageal malformations were found in 29.2% (±10.3), affecting five out of nine litters. Oesophageal atresia occurred in 15.6% (±8.1), laryngotracheo-oesophageal cleft in 10.4% (±7) and tracheal agenesis in 3.1% (±3.1). All of these malformations occurred with a tracheo-oesophageal fistula. Unlike the ARM, the AMM can produce fetuses with complete laryngotracheo-oesophageal cleft as well as oesophageal atresia or tracheal agenesis. Their occurrence was found to be reproducible but variable. These are important considerations when planning and interpreting experiments using this model.     

Synergistic effect of influenza a virus on endotoxin-induced mortality in rat pups: a potential model for sudden infant death syndrome

Sudden infant death syndrome is the most common cause of postneonatal infant mortality in the developed world. It is a diagnosis of exclusion with peak age of incidence between 2 and 6 mo. Fifty to 63% of these infants have a preexisting upper respiratory tract infection before death. We hypothesized that the immature immune system may be altered by a primary infection, preventing a protective response after secondary challenge. To mimic dual infection, we used a nonlethal strain of a rat-adapted influenza A virus and a sublethal dose of endotoxin to establish a model that results in pathology and death in 12-d-old rat pups similar to that seen in infants dying of sudden infant death syndrome. Mortality only occurred when specific criteria such as timing between infectious insults and developmental age of the pup were met. Results suggest that mortality is caused by a rapid systemic shock event rather than lung-specific damage. Gross pathologic findings such as lung petechiae and liquid blood around the heart on necropsy were consistent with those seen in infants dying of sudden infant death syndrome. Histopathologic lesions including subendocardial hemorrhage and mild cortical thymocyte necrosis were found with greater severity and frequency in dually challenged animals. Macrophage subpopulation in rat-adapted influenza A virus-inoculated animals was significantly elevated in the spleen at the time of death. Our model suggests that the developing immune system can be primed to respond in an exaggerated way to a second immune challenge resulting in unexpected death.     

Temporal and regional evolution of aquaporin-4 expression and magnetic resonance imaging in a rat pup model of neonatal stroke

Edema formation can be observed using magnetic resonance imaging (MRI) in patients with stroke. Recent studies have shown that aquaporin-4 (AQP4), a water channel, is induced early after stroke and potentially participates in the development of brain edema. We studied whether induction of AQP4 correlated with edema formation in a rat pup filament stroke model using high field (11.7-Tesla) MRI followed by immunohistochemical investigation of AQP4 protein expression. At 24 h, we observed increased T2 values and decreased apparent diffusion coefficients (ADC) within injured cortical and striatal regions that reflected the edema formation. Coincident with these MR changes were significant increases in AQP4 expression on astrocytic end-feet in the border regions of injured tissues. Striatal imaging findings were still present at 72 h with a slow normalization of AQP4 expression in the border regions. At 28 d, AQP4 expression normalized in the border while in this region ADC values increased. We show that induction of AQP4 is increased during the period of active edema formation in the border region without regional correlation with edema. Finally, induction of AQP4 on astrocyte end-feet could participate in tissue preservation after ischemia in the immature rat brain.     

Regression of retinopathy by squalamine in a mouse model

The goal of this study was to determine whether an antiangiogenic agent, squalamine, given late during the evolution of oxygen-induced retinopathy (OIR) in the mouse, could improve retinal neovascularization. OIR was induced in neonatal C57BL6 mice and the neonates were treated s.c. with squalamine doses begun at various times after OIR induction. A system of retinal whole mounts and assessment of neovascular nuclei extending beyond the inner limiting membrane from animals reared under room air or OIR conditions and killed periodically from d 12 to 21 were used to assess retinopathy in squalamine-treated and untreated animals. OIR evolved after 75% oxygen exposure in neonatal mice with florid retinal neovascularization developing by d 14. Squalamine (single dose, 25 mg/kg s.c.) given on d 15 or 16, but not d 17, substantially improved retinal neovascularization in the mouse model of OIR. There was improvement seen in the degree of blood vessel tuft formation, blood vessel tortuosity, and central vasoconstriction with squalamine treatment at d 15 or 16. Single-dose squalamine at d 12 was effective at reducing subsequent development of retinal neovascularization at doses as low as 1 mg/kg. Squalamine is a very active inhibitor of OIR in mouse neonates at doses as low as 1 mg/kg given once. Further, squalamine given late in the course of OIR improves retinopathy by inducing regression of retinal neovessels and abrogating invasion of new vessels beyond the inner-limiting membrane of the retina.     

产前感染对新生大鼠肺发育的影响

目的 动态观察产前炎症暴露后新生大鼠肺形态及炎症细胞表达变化,探讨产前感染对新生大鼠肺发育影响的病理机制.方法 Wistar孕鼠按照随机数字表分为实验组和对照组,分别于孕19d和20d腹腔注射脂多糖(lipopolysaccharide,LPS)2.5mg/kg和等量生理盐水,足月自然分娩后,于日龄1d、3d、7d、14d、21 d及28 d两组分别取8只新生鼠,麻醉处死后取肺组织,以髓过氧化物酶(myeloperoxidase,MPO)和CD68作为中性粒细胞及巨噬细胞标志物,计数炎症细胞数量、图像分析测定肺泡数量、肺泡面积占组织面积比例、肺泡间隔厚度.结果 随日龄增加,新生鼠肺泡数量、肺泡占组织面积比例逐渐增加,肺泡间隔变薄,实验组炎症细胞数量逐渐减少.日龄1d、3d、7d及14d,实验组平均肺泡数量(88、89、102、127,单位:个/mm2)明显少于同日龄对照组(105、109、123和156,单位:个/mm2),P分别为0.024、0.009、0.013和0.004;日龄1d、3d和7d,实验组肺泡占组织面积比例(0.552、0.603和0.533)明显大于同日龄对照组(0.478、0.485和0.404),P分别为0.003、0.001和0.000;日龄1d及3d,实验组肺泡间隔厚度(12.30和10.75,单位:μm)明显小于同日龄对照组(17.13和16.13,单位:μm),P分别为0.000和0.000.日龄1d、3d、7d及14d,实验组中性粒细胞数量(681、582、393和379,单位:个/mm2)明显多于同日龄对照组(164、211、145和179,单位:个/mm2),P分别为0.000、0.000、0.000及0.003;日龄1d、3d及7d,实验组巨噬细胞数量(613、578和337,单位:个/mm2)明显多于同日龄对照组(170、182和127,单位:个/mm2),P分别为0.000、0.000和0.000.结论 产前炎症暴露使新生大鼠肺泡增大,数量减少,炎症细胞增多.随着新生鼠日龄的增加,肺泡发育接近正常.     

Epithelial Bmp (Bone morphogenetic protein) signaling for bulbourethral gland development: a mouse model for congenital cystic dilation

The bulbourethral gland (BUG) is a male-specific organ, which secretes part of the semen fluid. As the BUG is located in the deep pelvic floor, its developmental process is still unclear. Bone morphogenetic protein (Bmp) signaling plays pivotal roles in various organs. However, the function of Bmp signaling for BUG development is still unclear. The present study aimed to elucidate the role of Bmp signaling in the development of the BUG. We observed the prominent nuclear accumulation of phosphorylated (p) SMAD1/5/8, the downstream molecules of Bmp signaling, during BUG epithelial development. These results suggest that Bmp signaling contributes to BUG development. Bmp receptor1a (Bmpr1a) is known as the major type 1 signal transducer in some organogeneses. To analyze the Bmp signaling function for BUG development, we examined epithelial cell-specific Bmpr1a gene conditional mutant mice utilizing the tamoxifen-inducible Cre recombinase system. We observed cystic dilation and epithelial hyperplasia of the BUG in the Bmpr1a conditional knockout mice. The mutant cystic BUG specimens also showed inflammatory lesions. These BUG abnormalities resembled some of the BUG malformations observed in human congenital syndromes. The current study suggests that Bmp signaling possesses an essential role in BUG development and homeostasis. This would be the first report showing that the mutation of the Bmpr1a gene in the BUG epithelia phenocopied some abnormalities of human congenital syndromes affecting the BUG duct.     

Preclinical testing of tandutinib in a transgenic medulloblastoma mouse model

Overexpression of platelet-derived growth factor receptor alpha (PDGFR-A) has been documented in association with primary tumors and metastasis in medulloblastoma. Tumors from our genetically engineered sonic hedgehog-driven medulloblastoma mouse model overexpress PDGFR-A in primary tumors and thus this mouse model is a good platform with which to study the role of PDGFR-A in this central nervous system malignancy. We hypothesized that inhibition of PDGFR-A in medulloblastoma can slow or inhibit tumor progression in living individuals. To test our hypothesis, we targeted PDGFR-A mediated tumor growth in vitro and in vivo using the tyrosine kinase inhibitor, tandutinib (MLN-518), which strongly inhibits PDGFR-A. Although PDGFR-A inhibition by this agent resulted in reduced mouse tumor cell growth and increased apoptosis in vitro, and reduced tumor cell proliferation in vivo, tandutinib did reduce tumor volume at the doses tested (360 mg/kg) in vivo. Thus, tandutinib may be an agent of interest for sonic hedgehog-driven medulloblastoma if a synergistic drug combination can be identified.     

Antibiotic-induced mesenteric adenopathy in an intussusception mouse model: a randomized, controlled trial

BACKGROUND: Idiopathic intussusception is a leading cause of intestinal obstruction in young children. Although the etiology remains obscure, lymphoid hyperplasia is found in a majority of cases. Antibiotics, the most frequently prescribed medication class in the pediatric population, have been recently associated with intussusception. The authors sought to determine whether enteral antibiotic exposure influences the development of mesenteric adenopathy, bowel dilation or intussusception in an animal model. MATERIALS AND METHODS: The authors conducted a randomized, controlled animal trial using a previously described intussusception model. Mice were gavaged with normal saline, amoxicillin-clavulanate or azithromycin twice daily for 5 days to assess the influence of enteral antibiotic exposure on intussusception, mesenteric adenopathy and bowel dilation. One pediatric surgeon performed all laparotomies and was blinded to group designation. Chi2 and Fisher exact tests were used to evaluate differences between antibiotic exposed and control groups. RESULTS: Mesenteric adenopathy was identified in 4.1% of the normal saline controls compared with 54.1% (P < 0.01) and 38.9% (P < 0.01) of the amoxicillin-clavulanate and azithromycin exposed animals, respectively. A total of four intussusceptions were observed in the antibiotic-exposed groups combined whereas no intussusception cases were identified in the control group (P = 0.30). CONCLUSIONS: This is the first study to describe a significant association between antibiotic use and mesenteric adenopathy in any animal species.     

Alendronate treatment for infants with osteogenesis imperfecta: demonstration of efficacy in a mouse model

Recent non-placebo-controlled studies of the bisphosphonate pamidronate have shown it to be effective in reducing fractures and improving bone density in infants and children with osteogenesis imperfecta (OI). To evaluate the effects of bisphosphonate treatment in a controlled study, the oim/oim mouse model of OI was studied. Nursing infant mouse pups (approximately 2 wk old) with moderate to severe OI (oim/oim mouse) and age- and background-matched control mice (+/+) were treated either with the third-generation bisphosphonate alendronate (ALN), or with saline. Fracture risk, bone quality, and growth were evaluated over a 12-wk treatment period. ALN at a dose of 0.03 mg/kg/d or saline was administered via s.c. injection to infant oim/oim and wild-type (+/+) mice from 2 to 14 wk of age (n = 20 per subgroup). The average number of fractures sustained by the ALN-treated oim/oim mice was reduced significantly compared with the untreated oim/oim mice (0.7 +/- 0.7 fractures/mouse versus 2.0 +/- 0.2 fractures/mouse). Bone density increased significantly in the femur and the spine with treatment (2.0 +/- 0.5 versus 1.2 +/- 0.5 in femur and 2.1 +/- 0.5 versus1.6 +/- 0.5 in spine). Histologic evaluation revealed the percentage of metaphyseal tibial bone increased significantly with treatment in both +/+ and oim/oim mice. Mechanical testing revealed an increase in structural stiffness for both treated +/+ and oim/oim mice compared with untreated animals. None of the material properties examined were significantly altered with treatment, nor was spinal curvature affected. Weight gain and long bone growth were comparable in the treated and untreated oim/oim mice. In wild-type mice, femur lengths were significantly shorter in the treated mice compared with untreated counterparts. This animal study demonstrates that treatment of OI in mice as early as 2 wk of age with ALN appears to be effective in reducing fractures and increasing bone properties. Based on the data from this study, ALN therapy in infants with OI should prove to be effective.     

先天性马蹄内翻足动物模型胚胎后肢(芽)评分系统的建立

Objective Quantification of the severity of congenital clubfoot is essential for its re-search and treatment. Up to date, no scoring system is available for hind limb bud development. In this study,a scoring system was established based on a murine model Methods Sixty female Wistar rats weighing 220～250 g were randomized into the six control groups and six experimental groups. Vaginal sperm plug detection day was considered to be day 0 of gestation. Hind limb buds from fetuses of E13, 14, 15,16,17 and 18 days were removed and processed. Results Morphogenetic differentiation changes were detected in the experimental groups. According the new scoring system, clubfoot-like deformity was present in 80.9% of the experimental fetuses. We were able to quantify the extent morphogenetic diffcrentiation of the hind limb accordingly. Conclusions Congenital clubfoot deformities begin at early developmental stage and become exaggerated as the fetuses mature. The scoring system can quantify the extent of congenital clubfoot deformity and facilitate its management.     

先天性马蹄内翻足动物模型胚胎后肢(芽)评分系统的建立

Objective Quantification of the severity of congenital clubfoot is essential for its re-search and treatment. Up to date, no scoring system is available for hind limb bud development. In this study,a scoring system was established based on a murine model Methods Sixty female Wistar rats weighing 220～250 g were randomized into the six control groups and six experimental groups. Vaginal sperm plug detection day was considered to be day 0 of gestation. Hind limb buds from fetuses of E13, 14, 15,16,17 and 18 days were removed and processed. Results Morphogenetic differentiation changes were detected in the experimental groups. According the new scoring system, clubfoot-like deformity was present in 80.9% of the experimental fetuses. We were able to quantify the extent morphogenetic diffcrentiation of the hind limb accordingly. Conclusions Congenital clubfoot deformities begin at early developmental stage and become exaggerated as the fetuses mature. The scoring system can quantify the extent of congenital clubfoot deformity and facilitate its management.     

先天性马蹄内翻足动物模型胚胎后肢(芽)评分系统的建立

Objective Quantification of the severity of congenital clubfoot is essential for its re-search and treatment. Up to date, no scoring system is available for hind limb bud development. In this study,a scoring system was established based on a murine model Methods Sixty female Wistar rats weighing 220～250 g were randomized into the six control groups and six experimental groups. Vaginal sperm plug detection day was considered to be day 0 of gestation. Hind limb buds from fetuses of E13, 14, 15,16,17 and 18 days were removed and processed. Results Morphogenetic differentiation changes were detected in the experimental groups. According the new scoring system, clubfoot-like deformity was present in 80.9% of the experimental fetuses. We were able to quantify the extent morphogenetic diffcrentiation of the hind limb accordingly. Conclusions Congenital clubfoot deformities begin at early developmental stage and become exaggerated as the fetuses mature. The scoring system can quantify the extent of congenital clubfoot deformity and facilitate its management.     

先天性马蹄内翻足动物模型胚胎后肢(芽)评分系统的建立

Objective Quantification of the severity of congenital clubfoot is essential for its re-search and treatment. Up to date, no scoring system is available for hind limb bud development. In this study,a scoring system was established based on a murine model Methods Sixty female Wistar rats weighing 220～250 g were randomized into the six control groups and six experimental groups. Vaginal sperm plug detection day was considered to be day 0 of gestation. Hind limb buds from fetuses of E13, 14, 15,16,17 and 18 days were removed and processed. Results Morphogenetic differentiation changes were detected in the experimental groups. According the new scoring system, clubfoot-like deformity was present in 80.9% of the experimental fetuses. We were able to quantify the extent morphogenetic diffcrentiation of the hind limb accordingly. Conclusions Congenital clubfoot deformities begin at early developmental stage and become exaggerated as the fetuses mature. The scoring system can quantify the extent of congenital clubfoot deformity and facilitate its management.     

先天性马蹄内翻足动物模型胚胎后肢(芽)评分系统的建立

Objective Quantification of the severity of congenital clubfoot is essential for its re-search and treatment. Up to date, no scoring system is available for hind limb bud development. In this study,a scoring system was established based on a murine model Methods Sixty female Wistar rats weighing 220～250 g were randomized into the six control groups and six experimental groups. Vaginal sperm plug detection day was considered to be day 0 of gestation. Hind limb buds from fetuses of E13, 14, 15,16,17 and 18 days were removed and processed. Results Morphogenetic differentiation changes were detected in the experimental groups. According the new scoring system, clubfoot-like deformity was present in 80.9% of the experimental fetuses. We were able to quantify the extent morphogenetic diffcrentiation of the hind limb accordingly. Conclusions Congenital clubfoot deformities begin at early developmental stage and become exaggerated as the fetuses mature. The scoring system can quantify the extent of congenital clubfoot deformity and facilitate its management.     

先天性马蹄内翻足动物模型胚胎后肢(芽)评分系统的建立

目的 建立一套稳定的评分系统,提供客观的观察指标来确认胚胎早期先天性马蹄内翻足(congenital clubfoot,CCF),进行序列胚胎研究.方法 60只Wistar大白鼠,体重220～250 g,随机分成实验组和对照组各6组.从怀孕第10天起,将维甲酸玉米油混悬液经胃管单次注入,以建立马蹄内翻足动物模型,分别在受孕第13、14、15、16、17、18天取出胎鼠的后肢芽并经过一系列处理.应用评分系统对胎鼠进行评分.结果 经评分系统得出的动物模型CCF发病率为80.9%,经评分系统矫正后的CCF发病率较既往报道高.在实验组和对照组之间的软骨分化存在显著差异.结论 应用评分系统可以有效地筛选出CCF,可以对筛选出的CCF胚胎在关键的研究时间窗口进行系列研究,有效地解决了长期困扰CCF研究难以深入的瓶颈问题.