Biomedical subjects

H Xia

Publications and source records attributed to H Xia.

At least 19 recordsLinked to original sources

PubMed2001

AsMamDB: an alternative splice database of mammals.

The objective of database AsMamDB is to facilitate the systematic study of alternatively spliced genes of mammals. Version 1.0 of AsMamDB contains 1563 alternatively spliced genes of human, mouse and rat, each associated with a cluster of nucleotide sequences. The main information provided by AsMamDB includes gene alternative splicing patterns, gene structures, locations in chromosomes, products of genes and tissues where they express. Alternative splicing patterns are represented by multiple alignments of various gene transcripts and by graphs of their topological structures. Gene structures are illustrated by exon, intron and various regulatory elements distributions. There are 4204 DNAs, 3977 mRNAs, 8989 CDSs and 126 931 ESTs in the current database. More than 130 000 GenBank entries are covered and 4443 MEDLINE records are linked. DNA, mRNA, exon, intron and relevant regulatory element sequences are provided in FASTA format. More information can be obtained by using the web-based multiple alignment tool Asalign and various category lists. AsMamDB can be accessed at http://166.111.30.65/ASMAMDB.html.

Alternative Splicing↗

PubMed2000

Enhanced secretion of ApoB by transfected HepG2 cells overexpressing fibrinogen.

HepG2 cells stably transfected with cDNA-encoding single fibrinogen chains overexpress fibrinogen and have increased (4-fold) secretion of apolipoprotein B. Overexpression of fibrinogen does not affect the secretion of three representative acute-phase proteins but causes a small increase in albumin secretion. Enhanced apolipoprotein B secretion is due to less intracellular degradation and not to increased expression. The increased secretion of apolipoprotein B is independent of the acute-phase response, since stimulation of fibrinogen gene expression by interleukin 6 did not affect secretion. HepG2 cells overexpressing fibrinogen chains had increased 3-hydroxy-3-methylglutaryl coenzyme A reductase mRNA levels, enhanced cholesterol production but normal levels of triglyceride and phospholipid synthesis and of sterol response binding proteins. These results, that associate overexpression of fibrinogen with enhance apolipoprotein B secretion, may be significant since epidemiological studies indicate that elevated levels of fibrinogen and lipids are independent risk factors in coronary artery disease.

Acute-Phase Proteins↗

PubMed2000

Potentiation of benzo[a]pyrene-induced pulmonary and forestomach tumorigenesis in mice by D,L-buthionine-S,R-sulfoximine-mediated tissue glutathione depletion.

In vitro studies have suggested that the glutathione (GSH) S-transferase (GST)-catalyzed GSH conjugation is an important mechanism for the detoxification of (+)-anti-7,8-dihydroxy-9, 10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE], which is the activated form of the widespread environmental pollutant benzo[a]pyrene (BP). However, in vivo experimental evidence for the importance of GSH/GST system in defense against carcinogenic effects of BP is lacking. We hypothesized that if GSH/GST were to play an important role in the detoxification of (+)-anti-BPDE, the tumorigenic activity of BP would be increased by depleting the levels of GSH, which is the required nucleophilic substrate for GST-catalyzed conjugation reactions. In the present study, we have tested the above hypothesis by determining the effect of D, L-buthionine-S,R-sulfoximine (BSO)-mediated tissue GSH depletion on BP-induced tumorigenesis of the lung and forestomach in female A/J mice. Treatment of mice with three i.p. injections of 2.5 mmol BSO/kg (12 h apart) plus 20 mM BSO in drinking water, resulted in a statistically significant reduction in hepatic, pulmonary and forestomach GSH levels. At the same time, BSO-administration caused a statistically significant increase in BP-induced pulmonary and forestomach tumor multiplicity. To the best of our knowledge, the present study is the first report that provides in vivo experimental evidence for the importance of GSH/GST system in cellular protection against carcinogenic effects of BP.

Animals↗

PubMed2000

Biochemical mechanism of cross-resistance to paclitaxel in a mitomycin c-resistant human bladder cancer cell line.

9-fold more resistant to mitomycin C (MMC) than parental cells (J82/WT). The IC(50) values for paclitaxel in J82/WT and J82/MMC-2 cell lines were 0.7+/-0.03 and 2.8+/-0.7 microM, respectively (P<0. 05). Thus, the J82/MMC-2 cell line exhibited 4-fold cross-resistance to paclitaxel compared with J82/WT. Intracellular accumulation of [(3)H]paclitaxel was comparable in J82/WT and J82/MMC-2 cell lines. There were no qualitative or quantitative differences between the J82/WT and J82/MMC-2 cell lines in terms of their alpha-tubulin and beta-tubulin contents. Paclitaxel-induced apoptosis could not be detected in either cell line over a wide range of drug concentrations. These results indicate that cross-resistance to paclitaxel in the J82/MMC-2 cell line is not linked to reduced drug accumulation, increased drug efflux, alterations in tubulin content or reduced paclitaxel-induced apoptosis. Paclitaxel-induced DNA strand breakage, however, determined by alkaline elution, was markedly lower in the J82/MMC-2 cell line than in J82/WT. These results suggest that paclitaxel cross-resistance in J82/MMC-2 may be attributed to reduced paclitaxel-induced DNA strand breakage. The precise mechanism of reduced paclitaxel-induced DNA strand breakage in J82/MMC-2 cell line relative to J82/WT cells, however, remains to be elucidated.

Antineoplastic Agents↗

PubMed2000

A simple method for the rapid generation of recombinant adenovirus vectors.

Recombinant adenoviruses are useful vectors for basic research. When the vectors are used for delineating protein function, several viruses, each containing a mutated version of the transgene are compared at the same time. However, methods to generate multiple vectors simultaneously within a short time period are cumbersome. In this report, we show that a novel backbone plasmid, when cotransfected with routinely used shuttle vectors into HEK293 cells allowed for production of recombinant viruses in an average of 14 days. The recombinant viruses had no detectable wild-type virus contamination by A549 plaque assay and only three to 300 E1a copies per 109 adenovirus genomes by a sensitive PCR-based assay. Further culturing or serial amplification did not result in wild-type revertants nor did cultures show increased levels of E1a copy number by quantitative PCR. Thus, recombinant adenovirus vectors can be produced very simply, rapidly and with little to no contaminating wild-type particles. This system should facilitate the generation of multiple genetic variants by eliminating the need for time-consuming plaque purification and the need to manipulate and screen very large plasmids. We call this the RAPAd.I system.

Adenoviridae↗

PubMed2000

Reporter gene imaging: effects of ganciclovir treatment on nucleoside uptake, hypoxia and perfusion in a murine gene therapy tumour model that expresses herpes simplex type-1 thymidine kinase.

Perfusion, hypoxia and nucleoside uptake during ganciclovir therapy were determined in a murine HSV-1 TK-expressing tumour model (KBALB-STK). HSV-1 TK mRNA transcription in this cell line was confirmed by RT-PCR. BALB/c mice bearing KBALB-STK tumours accumulated (E)-5-(2-[125I]iodovinyl)-2'-fluoro-2'-deoxyuridine ([125I]IVFRU) (2.54% injected dose.g-1) and could be readily detected with planar imaging following administration of [131I]IVFRU. However, a single dose of ganciclovir (100 mg.kg-1 intraperitoneally) decreased tumour uptake of [125I]IVFRU to 0.33% injected dose.g-1. Subsequent single daily doses of ganciclovir over 3 consecutive days had a negligible effect on [125I]IVFRU uptake, which remained low. Tumour perfusion during 3 days of ganciclovir treatment was monitored with intravenous [99Tcm]HMPAO. Tumour perfusion increased from day 0 (no ganciclovir treatment) with 1.83% injected dose.g-1 tumour, to a maximum at day 2 (3.77% injected dose.g-1). In the same animals, accumulation of [3H]misonidazole decreased from 0.70% injected dose.g-1 at day 0 to a minimum at day 3 (0.24% injected dose.g-1), indicating that tumour tissue had become less hypoxic over the ganciclovir regimen. The uptake of [125I]IVFRU into the acid insoluble fraction of KBALB-STK cells in vitro in the presence of ganciclovir (2.0 microM) was completely inhibited, leading to a 57% decrease in total cellular accumulation of radioactivity. However, cytosolic entrapment of [125I]IVFRU was not affected by the presence of ganciclovir. These results indicate that the mechanisms leading to IVFRU exclusion during ganciclovir treatment of HSV-1 TK-expressing tumours can be attributed, at least partially, to inhibition of [125I]IVFRU-nucleotide incorporation into DNA.

Animals↗

PubMed2000

Recombinant human adenovirus: targeting to the human transferrin receptor improves gene transfer to brain microcapillary endothelium.

Some inborn errors of metabolism due to deficiencies of soluble lysosomal enzymes cause global neurodegenerative disease. Representative examples include the infantile and late infantile forms of the ceroid lipofuscinoses (CLN1 or CLN2 deficiency, respectively) and mucopolysaccharidoses type VII (MPS VII), a deficiency of beta-glucuronidase. Treatment of the central nervous system component of these disorders will require widespread protein or enzyme replacement, either through dissemination of the protein or through dissemination of a gene encoding it. We hypothesize that transduction of brain microcapillary endothelium (BME) with recombinant viral vectors, with secretion of enzyme product basolaterally, could allow for widespread enzyme dissemination. To achieve this, viruses should be modified to target the BME. This requires (i) identification of a BME-resident target receptor, (ii) identification of motifs targeted to that molecule, (iii) the construction of modified viruses to allow for binding to the target receptor, and (iv) demonstrated transduction of receptor-expressing cells. In proof of principal experiments, we chose the human transferrin receptor (hTfR), a molecule found at high density on human BME. A nonamer phage display library was panned for motifs which could bind hTfR. Forty-three clones were sequenced, most of which contained an AKxxK/R, KxKxPK/R, or KxK motif. Ten peptides representative of the three motifs were cloned into the HI loop of adenovirus type 5 fiber. All motifs tested retained their ability to trimerize and bind transferrin receptor, and seven allowed for recombinant adenovirus production. Importantly, the fiber-modified viruses facilitated increased gene transfer (2- to 34-fold) to hTfR expressing cell lines and human brain microcapillary endothelia expressing high levels of endogenous receptor. Our data indicate that adenoviruses can be modified in the HI loop for expanded tropism to the hTfR.

Adenoviruses, Human↗

PubMed2000

Neural crest-derived defects in experimental esophageal atresia.

Esophageal atresia (EA) is often associated with cardiovascular and other malformations that are likely neural crest derived. The present study tests the hypothesis that the heart and great vessels and the thymus and parathyroids may be abnormal in the rat model of EA as a result of disturbed neural crest development. Time-mated pregnant rats received intraperitoneally on d 8 and 9 of gestation either 2 mg/kg adriamycin or vehicle. Esophageal, heart, and thymic malformations were sought under the microscope in term fetuses. The parathyroids were histologically investigated. Control fetuses had no malformations, whereas 69 of 109 fetuses exposed to adriamycin had EA and 45 of 69 had 15 right aortic arches, nine aberrant right subclavia, eight ventricular septal defects, six narrow pulmonary outflow tracts, five tetralogies of Fallot, three double outflow right ventricles, three double aortic arches, three atrial septal defects, three right ductus arteriosus, and two truncus. The thymus was absent in 19, hypoplastic in 12, and ectopic in five out of 36 fetuses with EA in which it was studied, whereas the parathyroid glands were absent in 16, single in four, and ectopic in one of the 23 fetuses with EA in which they were studied. In conclusion, the nature of the cardiovascular, thymic, and parathyroid malformations associated with EA in rats is consistent with the hypothesis of neural crest participation in their pathogenesis. Mechanisms simultaneously disturbing foregut septation, somitic segmentation, and neural crest development should be sought to explain the combined occurrence of malformations in EA.

Animals↗

PubMed1999

Dynamin-dependent endocytosis of ionotropic glutamate receptors.

Little is known about the mechanisms that regulate the number of ionotropic glutamate receptors present at excitatory synapses. Herein, we show that GluR1-containing alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors (AMPARs) are removed from the postsynaptic plasma membrane of cultured hippocampal neurons by rapid, ligand-induced endocytosis. Although endocytosis of AMPARs can be induced by high concentrations of AMPA without concomitant activation of N-methyl-D-aspartate (NMDA) receptors (NMDARs), NMDAR activation is required for detectable endocytosis induced by synaptically released glutamate. Activated AMPARs colocalize with AP2, a marker of endocytic coated pits, and endocytosis of AMPARs is blocked by biochemical inhibition of clathrin-coated pit function or overexpression of a dominant-negative mutant form of dynamin. These results establish that ionotropic receptors are regulated by dynamin-dependent endocytosis and suggest an important role of endocytic membrane trafficking in the postsynaptic modulation of neurotransmission.

Adaptor Protein Complex 2↗

PubMed1999

Metabolic fate of glutathione conjugate of benzo[a]pyrene-(7R,8S)-diol (9S,10R)-epoxide in human liver.

Benzo[a]pyrene-(7R,8S)-diol (9S,10R)-epoxide [(+)-anti-BPDE] is believed to be the activated form of the widely spread environmental pollutant benzo[a]pyrene. Glutathione (GSH) S-transferase (GST)-catalyzed conjugation of (+)-anti-BPDE with GSH is an important mechanism in its cellular detoxification. Here, we report that the GSH conjugate of (+)-anti-BPDE [(-)-anti-BPD-SG] is a potent inhibitor (K(i) 15 microM) of class Mu human GST isoenzyme, which, among human liver GSTs, is a highly efficient detoxifier of (+)-anti-BPDE. Thus, the inhibition of GST activity by (-)-anti-BPD-SG may hinder GSH conjugation of (+)-anti-BPDE, unless the conjugate is metabolized and/or eliminated. The results of the present study show that gamma-glutamyltranspeptidase (gamma-GT) can metabolize (-)-anti-BPD-SG at a rate of about 0.29 nmol/min/mg protein. Our studies also show that (-)-anti-BPD-SG is transported across the human canalicular liver plasma membrane (cLPM) in an ATP-dependent manner at a rate of about 0.33 nmol/min/mg protein. The ATP-dependent transport of (-)-anti-[(3)H]BPD-SG across human cLPM follows Michaelis-Menten kinetics (K(m) 84 microM; V(max) 0.33 nmol/min/mg). In conclusion, the results of the present study suggest that both gamma-GT-mediated metabolism and ATP-dependent canalicular transport may be important steps in overall detoxification of (+)-anti-BPDE in the human liver.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗

PubMed1999

The degradation of nascent fibrinogen chains is mediated by the ubiquitin proteasome pathway.

Recent studies have shown that ubiquitin-dependent proteolysis by proteasomes plays an essential role in the degradation of ER-retained proteins. We investigated the degradation of individual fibrinogen chains in transfected COS cells which express but do not secrete single chains. In transfected COS cells, the degradation of fibrinogen Bbeta and gamma chain was markedly inhibited by the proteasome inhibitors lactacystin and MG132. These specific proteasome inhibitors also partially affected the degradation of Aalpha chain. In HepG2 cells, which synthesize and secrete fibrinogen, the degradation of intracellular free gamma chain was also inhibited by MG132. We also detected high molecular weight polyubiquitinated forms of fibrinogen chains in transfected COS cells and in HepG2 cells by sequential immunoprecipitation. These results implicate proteasomes in the degradation of fibrinogen chains. In COS cells, gamma chains have a longer half-life than Bbeta chains and Aalpha chains, suggesting that the presence of surplus gamma chains in fibrinogen-producing cells is due to the unequal degradation rate of fibrinogen chains. These results indicate that the ubiquitin-proteasome pathway may be a major system for the degradation of unassembled fibrinogen chains.

Acetylcysteine↗

PubMed1999

Amino acid substitutions at positions 207 and 221 contribute to catalytic differences between murine glutathione S-transferase Al-1 and A2-2 toward (+)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9, 10-tetrahydrobenzo[a]pyrene.

We have previously identified a novel Alpha class murine glutathione (GSH) S-transferase isoenzyme (designated mGSTAl-2) which is exceptionally efficient in catalyzing the GSH conjugation of (+)-anti-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(+)-anti-BPDE], the ultimate carcinogen of widespread environmental pollutant benzo[a]pyrene. Furthermore, we have demonstrated that the Al-type subunit of this isoenzyme is significantly more active toward (+)-anti-BPDE than the other subunit (mGSTA2). To establish the basis for catalytic differences between mGSTAl and mGSTA2, which differ in their primary structures by 10 amino acids [distributed in three sections (I-III) as clusters of two (residues 65 and 95), three (residues 157, 162, and 169), and five (residues 207, 213, 218, 221, and 222) amino acids], three chimeric enzymes were expressed and tested for their activity toward (+)-anti-BPDE. These studies revealed that amino acid substitution(s) in section III determined the high catalytic activity of mGSTAl. Molecular modeling studies suggested that amino acid substitutions at positions 207 and/or 221, but not at positions 213, 218, and 222, may be responsible for such a difference. To test this possibility, amino acids at positions 207 and 221 of mGSTAl were mutated with the equivalent residues of mGSTA2. Kinetic analysis of the wild type and the mutant enzymes revealed that both methionine-207 and isoleucine-221 are critical for higher activity of mGSTA1-1 toward (+)-anti-BPDE compared with that of mGSTA2-2.

Amino Acid Substitution↗

PubMed1999

Human placental Na+-dependent multivitamin transporter. Cloning, functional expression, gene structure, and chromosomal localization.

We have cloned the human Na+-dependent multivitamin transporter (SMVT), which transports the water-soluble vitamins pantothenate, biotin, and lipoate, from a placental choriocarcinoma cell line (JAR). The cDNA codes for a protein of 635 amino acids with 12 transmembrane domains and 4 putative sites for N-linked glycosylation. The human SMVT exhibits a high degree of homology (84% identity and 89% similarity) to the rat counterpart. When expressed in HRPE cells, the cDNA-induced transport process is obligatorily dependent on Na+ and accepts pantothenate, biotin, and lipoate as substrates. The relationship between the cDNA-specific uptake rate of pantothenate or biotin and Na+ concentration is sigmoidal with a Na+:vitamin stoichiometry of 2:1. The human SMVT, when expressed in Xenopus laevis oocytes, induces inward currents in the presence of pantothenate, biotin, and lipoate in a Na+-, concentration-, and potential-dependent manner. We also report here on the structural organization and chromosomal localization of the human SMVT gene. The SMVT gene is approximately 14 kilobase pairs in length and consists of 17 exons. The SMVT gene is located on chromosome 2p23 as evidenced by somatic cell hybrid analysis and fluorescence in situ hybridization.

Amino Acid Sequence↗

PubMed1999

Gender related differences in ATP-dependent transport of dinitrophenyl-glutathione conjugate across murine canalicular liver plasma membrane.

The present study reports gender related differences in ATP-dependent transport of dinitrophenyl-glutathione (GSH) conjugate (DNP-SG), a model GSH xenobiotic conjugate, across murine canalicular liver plasma membrane (cLPM). ATP-dependent transport of DNP-SG across female A/J mouse cLPM was mediated by two components, a high-affinity and a low-affinity component, with corresponding Km of 18 microM (Vmax 0.02 nmol/min.mg) and 500 microM (Vmax 0.23 nmol/min.mg), respectively. On the other hand, only one component for the ATP-dependent transport of DNP-SG was observed in male mouse cLPM (K(m) 130 microM; Vmax 0.18 nmol/min.mg). Moreover, the rate of ATP-dependent transport of DNP-SG was markedly higher in the cLPM fraction of male mouse compared with that of the female. Presence of two transport components in female mouse cLPM, but only one system in the cLPM fraction of male mouse, was confirmed by measuring DNP-SG mediated stimulation of ATP hydrolysis (DNP-SG ATPase activity). To the best of our knowledge, the present study is the first report on gender related differences in ATP-dependent murine canalicular transport of GSH conjugates.

Adenosine Triphosphate↗

PubMed1999

The tracheobronchial tree is abnormal in experimental congenital diaphragmatic hernia.

Neonates with congenital diaphragmatic hernia (CDH) have other malformations that contribute to the high mortality. The nitrofen rat model allows experimental study of these anomalies. This study examines whether the tracheobronchial tree is also abnormal in this model. Time-mated rats received 100 mg nitrofen on gestational day 9. 5; 90 fetuses were harvested on day 21 (near full term) and dissected. The trachea and bronchi were stained with alcian blue-alizarin red and their anatomy was examined by transillumination under a microscope. The findings were compared with those of 11 suitable controls. Control pups had no malformations. Those with CDH (n = 57) had significantly decreased numbers of tracheal rings in comparison with controls (22.9 +/- 1.9 vs 26 +/- 1.9, P < 0.05) and 40/57 had fragmented rings (0 in controls). Twelve CDH animals had, in addition, tracheal stenoses of variable severity, sometimes related to vascular rings. Nitrofen fetuses without CDH (n = 33) had only short tracheas and 4 had mild stenoses. Nitrofen-exposed fetuses have, in addition to lung hypoplasia and sometimes CDH, severe tracheobronchial anomalies that suggest the involvement of pathogenetic mechanisms capable of acting on various tissue components. The genetic control of organogenesis is most probably disturbed by the teratogen.

Animals↗

PubMed1999

Lung hypoplasia caused by nitrofen is mediated by down-regulation of thyroid transcription factor TTF-1.

Prenatal exposure to nitrofen induces lung hypoplasia and diaphragmatic hernias very similar to those in human disease, but the mechanisms are still unknown. Thyroid transcription factor 1 (TTF-1) is involved in lung ontogeny and regulation of the expression of surfactant proteins, and is likely abnormally expressed in nitrofen-induced lung hypoplasia. This study examines the effect of nitrofen on TTF-1 messenger RNA (mRNA) expression in the lungs of prenatal rat fetuses and a human lung-cell line (NCI-H441) that expresses both TTF-1 and surfactant proteins in vivo. Lungs from preterm fetuses harvested from rats with 100 mg nitrofen on gestational day 9.5 and NCI-H441 cells maintained in RPMI medium containing 10% fetal bovine serum and exposed to nitrofen for different times and concentrations were assayed for TTF-1 mRNA by northern blot analysis. mRNA for TTF-1 was decreased in nitrofen-exposed pups in comparison with controls, and exposure to nitrofen caused a dose- and time-related decrease in TTF-1 expression in H441 cell cultures. These results indicate that nitrofen downregulates TTF-1 both in vivo and in vitro. Since this interferes with lung development, it is reasonable to accept that lung hypoplasia in this model is in part due to the direct effect of the teratogen rather than to compression by the abdominal viscera herniated into the thorax. This mechanism should be explored in the clinical setting.

Animals↗

PubMed1999

Cardiovascular malformations in congenital diaphragmatic hernia: human and experimental studies.

BACKGROUND/PURPOSE: Cardiovascular malformations (CVM) associated with congenital diaphragmatic hernia (CDH) account in part for the high mortality caused by this defect. The aim of this study is to examine the nature of these malformations in a large series of autopsies and to assess if similar defects are also present in rat fetuses with experimental CDH. METHODS: The incidence of CVM and their nature were examined in the autopsy records of 136 stillborns and neonates with CDH admitted to our institution in the last 30 years. Experimental CDH was induced in rat fetuses by giving 100 mg of nitrofen to their mothers on gestational day 9.5, and the fetuses were harvested on day 21 (near full term). The presence of CDH and the anatomy of the heart and great vessels were studied under dissecting microscope after formalin fixation. Unexposed fetuses were used as controls. RESULTS: Thirty-three newborns with CDH (24%) had CVM, either isolated or associated with other defects, and 7 had heart hypoplasia. Most CVM (ventricular septal defect, tetralogy of Fallot, transposition of the great vessels, double-outlet right ventricle) involved the outflow tract. In our animal experiments, no malformations were found in 21 control pups. Conversely, 80 of 130 nitrofen-exposed fetuses (61%) had CDH, and 59 of them (74%) had CVM. A significant association (Fisher's Exact test, P<.01) was found between CDH and CVM because only 25 of the 50 exposed animals without CDH (50%) had CVM. Again, most defects involved the outflow tract and were similar to those seen in human CDH (tetralogy of Fallot, persistent truncus, ventricular septal defect, double-outlet right ventricle, aberrant right subclavian artery, agenetic ductus, and interrupted aortic arch). Animals with CDH had significantly decreased heart weight to fetal weight ratio in comparison with controls and with those without CDH. CONCLUSIONS: The similar nature of the cardiovascular defects found in babies succumbing to CDH and in nitrofen-exposed rats suggests that a similar disturbance of the regional organogenesis related to the neural crest might be involved in both settings, and further validates the use of this animal model for clarifying the cellular and molecular pathogenetic mechanisms.

Animals↗

PubMed1999

Skeletal malformations associated with esophageal atresia: clinical and experimental studies.

BACKGROUND/PURPOSE: Patients with esophageal atresia (EA) often have skeletal malformations. The purpose of this study is to examine if similar defects occur in rat fetuses prenatally exposed to Adriamycin, a chemical capable of causing EA in these animals. METHODS: The charts of 443 babies with EA were reviewed to assess the incidence and nature of these defects in them. Time-mated female rats were given either 2 mg/kg intraperitoneal Adriamycin (experimental group, n = 16) or no treatment (control group, n = 4) on gestational days 8 and 9, and the fetuses were removed near term. Skeletal anatomy was studied after alcian blue and alizarin red staining. RESULTS: A total of 528 skeletal malformations, mainly abnormal segmentation and vertebral identity (extra or defective bodies or ribs), mishaped vertebral bodies, and limb malformations like radial aplasia or hypoplasia were found in 245 babies (55%). Costal fusion and sternal anomalies were present in 17 and 4 babies, respectively. In the animal study, all control fetuses were normal, whereas 83 of 134 experimental fetuses (62%) had EA accompanied by other malformations. No segmentation or vertebral identity anomalies were seen, but butterfly, wedged, and asymmetric vertebral bodies were found at various levels in all animals with EA and in about half of those without it. Three fetuses had rib anomalies, and 3 more had sternal malformations. Ossification of limbs was delayed in treated fetuses and short, thick, and crooked bones were seen in 4 of 31 fetuses with EA and in none of the Adriamycin-exposed ones without EA. CONCLUSIONS: Adriamycin exposure induces in fetal rats, in addition to esophageal, duodenal, and anorectal atresias, high proportions of vertebral malformations and some limb defects of nature not identical but quite similar to that of babies with EA. This further validates this model for investigating the nature of the processes leading to EA and its associated malformations.

Animals↗