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L F Dove

Publications and source records attributed to L F Dove.

15 recordsLinked to original sources
PubMed2001

TGF beta 2, LIF and FGF2 cooperate to induce nephrogenesis.

The metanephric kidney develops from interactions between the epithelial ureteric bud and adjacent metanephric mesenchyme, which is induced by the bud to form the epithelia of the nephron. We have found that leukemia inhibitory factor (LIF) and transforming growth factor beta 2 (TGF beta 2) are secreted by inductive rat bud cells and cooperate to enhance and accelerate renal tubule formation in uninduced rat metanephric mesenchymal explants. LIF alone or TGF beta 2 with fibroblast growth factor 2 induced numerous tubules in isolated mesenchymes over an 8 day period, while (in combination) all three caused abundant tubule formation in 72 hours. Furthermore, neutralization of Wnt ligands with antagonist-secreted Frizzled-related protein 1 abrogated these responses and combinatorial cytokine/growth factor stimulation of explants augmented nuclear activation of Tcf1/Lef1, suggesting that LIF and TGF beta 2/FGF2 cooperate to regulate nephrogenesis through a common Wnt-dependent mechanism.

Activin Receptors, Type I↗
PubMed2000

Mesenchymal-epithelial transition in the developing metanephric kidney: gene expression study by differential display.

The developing metanephric kidney is a convenient model to study molecular events associated with epithelial cell differentiation. To determine the genes involved in the defining event of this process, namely, the conversion of metanephric mesenchyme to the epithelium of the nephron, we applied differential display (DD) techniques. Explants of rat metanephric mesenchymes were induced to condense ex vivo with fibroblast growth factor 2 (FGF2) or to form tubules with FGF2 and conditioned medium (CM) from a cell line (RUB1) of ureteric bud, the renal inductive tissue. Three time points (6, 24, and 72 h) were chosen to track the dynamics of gene expression during morphogenesis. Seventy-two up- or down-regulated mRNAs were identified, including 36 novel sequences and those of cell cycle regulatory proteins (TGF-beta2, Cyclin D1, p57Kip2), transcription factors (beta-catenin, Sox11, DP1), signaling proteins (SH3-domain binding protein, G-protein-coupled receptor, Ser-Thr protein kinase), cell adhesion molecules (syndecan-4, integrin-beta1), and also gene33, H19, SM20, IGFBP5, MAMA receptor, lectin, keratin, beta-tubulin, calreticulin, GRP78, ERp72, MnSoD, thioredoxin, and others. Some have previously been associated with kidney development and serve as good controls for expected changes, while most have not been linked with kidney epithelial cell differentiation. Using thin sections of embryonic kidney and labeled antisense RNA probes, we applied RNA hybridization to confirm the results of DD and related the expression of these genes to specific cell lineages of the developing kidney. These results provide a window into the events that mediate this critical differentiation process and suggest that a limited number of interrelated events direct the epithelial conversion of metanephric mesenchyme. genesis 27:22-31, 2000. Published 2000 Wiley-Liss, Inc.

Animals↗
PubMed1999

neu mutation in schwannomas induced transplacentally in Syrian golden hamsters by N-nitrosoethylurea: high incidence but low allelic representation.

Peripheral nerve tumors (PNT) and melanomas induced transplacentally on day 14 of gestation in Syrian golden hamsters by N-nitrosoethylurea were analyzed for activated oncogenes by the NIH 3T3 transfection assay, and for mutations in the neu oncogene by direct sequencing, allele-specific oligonucleotide hybridization, MnlI restriction-fragment-length polymorphism, single-strand conformation polymorphism, and mismatch amplification mutation assays. All (67/67) of the PNT, but none of the melanomas, contained a somatic missense T --> A transversion within the neu oncogene transmembrane domain at a site corresponding to that which also occurs in rat schwannomas transplacentally induced by N-nitrosoethylurea. In only 2 of the 67 individual hamster PNT did the majority of tumor cells appear to carry the mutant neu allele, in contrast to comparable rat schwannomas in which it overwhelmingly predominates. The low fraction of hamster tumor cells carrying the mutation was stable through multiple transplantation passages. In the hamster, as in the rat, specific point-mutational activation of the neu oncogene thus constitutes the major pathway for induction of PNT by transplacental exposure to an alkylating agent, but the low allelic representation of mutant neu in hamster PNT suggests a significant difference in mechanism by which the mutant oncogene acts in this species.

Alkylating Agents↗
PubMed1996

Conditioned medium from a rat ureteric bud cell line in combination with bFGF induces complete differentiation of isolated metanephric mesenchyme.

Differentiation of metanephric mesenchyme is triggered by an inductive signal(s) from the epithelial ureteric bud. As a result of this induction, most of the metanephric mesenchyme converts into epithelium of a nephron. We have developed and characterized an explant culture system, in which metanephric mesenchyme can grow and completely differentiate in vitro in the absence of an inductive tissue. When separated 13 dpc rat metanephric mesenchymes were cultured in serum-free conditioned medium from a rat ureteric bud cell line (RUB1) in the presence of bFGF and TGFalpha, they were induced to differentiate into nephron epithelia and glomeruli-like structures. The nephric type of differentiation was confirmed by both morphological and molecular criteria and paralleled the developmental changes of nephron differentiation in vivo. Expression patterns of brush-border antigen as well as molecular markers of kidney differentiation Wt1, Lim1, Hgf and c-met, c-ret, Shh, Wnt4, Wnt7b, and Wnt11 were analyzed in explants by whole mount and tissue section in situ hybridization following 1-9 days in culture. The expression of secreted patterning molecules Bmp7 and Wnt7b, but not Shh or Wnt11, were demonstrated by RT-PCR and northern blot hybridization with RNA from the RUB1 cells. Our culture system lends itself to examining the relevance of these and other signaling molecules required for nephron differentiation.

Animals↗
PubMed1995

Basic fibroblast growth factor can mediate the early inductive events in renal development.

The earliest characterized events during induction of tubulogenesis in renal anlage include the condensation or compaction of metanephrogenic mesenchyme with the concurrent upregulation of WT1, the gene encoding the Wilms tumor transcriptional activator/suppressor. We report that basic fibroblast growth factor (FGF2) can mimic the early effects of an inductor tissue by promoting the condensation of mesenchyme and inhibiting the tissue degeneration associated with the absence of an inductor tissue. By in situ hybridization, FGF2 was also found to mediate the transcriptional activation of WT1 and of the hepatocyte growth factor receptor gene, c-met. Although FGF2 can induce these early events of renal tubulogenesis, it cannot promote the epithelial conversion associated with tubule formation in metanephrogenic mesenchyme. For this, an undefined factor(s) from pituitary extract in combination with FGF2 can cause tubule formation in uninduced mesenchyme. These findings support the concept that induction in kidney is a multiphasic process that is mediated by more than a single comprehensive inductive factor and that soluble molecules can mimic these inductive activities in isolated uninduced metanephrogenic mesenchyme.

Animals↗
PubMed1991

Induction of tubules in rat metanephrogenic mesenchyme in the absence of an inductive tissue.

Differentiation of metanephrogenic mesenchyme to renal tubular epithelium requires induction by the ureteric bud in vivo or any of several embryonic tissues in vitro. In an effort to eliminate the tissue requirement in embryonic induction, extracellular matrices and soluble factors were analyzed individually or in combination for their ability to stimulate tubulogenesis in uninduced metanephrogenic mesenchyme from 13-gestation-day rat embryos. These evaluations have established that pituitary extract and epidermal growth factor (EGF) in concert with a matrix can promote morphogenesis of mesenchymal rudiments in culture. While type I collagen, laminin, or fibronectin matrices all promoted tubulogenesis in the presence of pituitary extract and EGF, type IV collagen proved the most effective. Under these conditions, tubules were induced in 23/24 mesenchymal rudiments by 9 days in culture. Mesenchyme was not induced prior to explanation since it formed no tubules when cultured in a medium that allowed tubulogenesis in intact embryonic kidneys. Preliminary characterization of the undefined factor in pituitary extract was consistent with a protein of molecular weight greater than 100,000 but less than 300,000. When uninduced metanephrogenic mesenchyme from mouse was used instead of rat tissue, a similar pattern of morphogenesis was not observed, suggesting that the described medium is inappropriate for promoting differentiation in mouse or, less likely, that different mechanisms mediate differentiation in rat and mouse. These studies show that embryonic induction can occur in explanted rat renal mesenchyme in an appropriate environment and does not require the presence of an inductive tissue.

Animals↗
PubMed1989

Evaluation of the transplacental tumorigenicity of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone in mice.

The transplacental tumorigenicity of the tobacco-specific carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) was assessed in three strains of mice: A/J; C3H/He x C57BL/6 F1 (hereafter called C3B6F1); and Swiss outbred [Cr:NIH(S)]. NNK (100 mg/kg) was administered i.p. on Days 14, 16, and 18 of gestation to A/J and C3H/He mice and on Days 15, 17 and 19 of gestation to the Swiss mice. The effects of postnatal treatment with tumor-promoting agents, including 0.05% sodium barbital in the drinking water until death or a single dose of Aroclor 1254 (a mixture of polychlorinated biphenyls, PCB) given on Postnatal Day 8 or 56, were also examined. Progeny were sacrificed at age 24 wk (A/J) or 72 wk (C3B6F1 and Swiss). Significant incidences of tumors occurred in the lungs of strain A/J progeny and in the livers of male C3B6F1 and Swiss progeny. Lung tumor incidence was 8 of 34 (24%) in the female offspring of the A/J mice treated with NNK, compared with 1 of 39 (3%) in controls (P less than 0.05). A 2-fold difference in lung tumor incidence in male offspring of NNK-treated (4 of 23, 13%) versus control (3 of 48, 6%) A/J mice was not of statistical significance. However, the incidence of lung tumors in NNK-exposed progeny A/J mice in both sexes combined (12 of 66, 18%) was also significantly greater than in controls (4 of 87, 5%). The incidence of liver tumors in the male C3B6F1 mice exposed transplacentally to NNK was 12 of 30 (40%) compared to 8 of 46 (17%) in controls (P less than 0.05). No effects of postnatal sodium barbital or PCB were observed on transplacental NNK tumorigenicity in C3B6F1 mice. The combined incidence of liver carcinoma in male mice in all NNK-treated groups (13 of 141, 9%) was significantly greater (P less than 0.05) than in controls (5 of 144, 3%). In male Swiss mice exposed transplacentally to NNK, the incidence of liver tumors was 3 of 57 (5%) compared to 0 of 35 controls, and postnatal treatment with PCB on Day 56 caused a significant increase (5 of 26, 19%) (P less than 0.05) in the incidence of NNK-induced liver tumors. The combined incidence of liver tumors in the male offspring of the Swiss mice treated with NNK, with or without PCB, was 8 of 83 (10%) which was significantly greater (P less than 0.05) than in controls (0 of 66).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1985

Selective growth in culture of fetal rat renal collecting duct anlagen. Morphologic and biochemical characterization.

Cell culture conditions were devised that selectively supported growth of 13 or 14 gestation day F344 rat ureteric bud, the renal collecting duct anlagen. These same conditions also inhibited the growth of metanephrogenic mesenchyme, precursor of structures proximal to the duct. Isolated buds were cultured in Ham's F12 medium supplemented with epidermal growth factor, selenium, insulin, hydrocortisone, prostaglandin E1, transferrin, and triiodothyronine; fetal bovine serum (1%) was required for continuous propagation. Cultured cells were epithelial in morphology and formed domes. By electron microscopy, many structural characteristics of highly differentiated cells were evident: numerous mitochondria, Golgi apparatus, extensive endoplasmic reticulum, an occasional cilium, intracytoplasmic filaments, polarized formation of microvilli, and gap junctions. Histochemistry revealed considerable functional differentiation as well. Cultured bud cells, adult collecting duct, and fetal duct anlagen were positive for acid phosphatase, membrane-localized ATPase, and nonspecific esterase. Bud cells and fetal duct anlagen expressed high levels of gamma-glutamyl transpeptidase activity while adult collecting duct exhibited slight activity. In addition, immunocytochemical observation of intermediate filament expression revealed the presence of epithelial cytokeratins but absence of mesenchymal vimentin in cultured bud cells and fetal and adult collecting ducts. These results indicate that the culture conditions described can maintain the partially differentiated fetal collecting duct anlagen in a state consistent with its embryonal derivation, and therefore may be useful in culture studies of renal differentiation.

Acid Phosphatase↗
PubMed1985

Comparative tumor-promoting activities of phenobarbital, amobarbital, barbital sodium, and barbituric acid on livers and other organs of male F344/NCr rats following initiation with N-nitrosodiethylamine.

Tumor-promoting abilities of four barbiturates, phenobarbital [(PB) CAS: 50-06-6], amobarbital [(AB) CAS: 57-43-2], barbital sodium [(BB) CAS: 144-02-5], and barbituric acid [(BA) CAS: 67-52-7], on the development of neoplasms in livers and other organs of rats following initiation with N-nitrosodiethylamine [(DENA) CAS: 55-18-5] were compared. Four-week-old F344/NCr male rats were given a single ip injection of 75 mg DENA/kg body weight. Beginning 2 weeks later, they were given either tap water (group 1) or drinking water containing 500 ppm of PB (group 2), the sodium salt of BB (group 3), AB (group 4), or BA (group 5) for the remaining experimental period. Control groups (groups 6-10) received an ip injection of saline alone and 2 weeks later were given either tap water or drinking water containing barbiturates as listed above. Animals were sacrificed at either 52 weeks or 78 weeks. None of the barbiturates altered the growth and survival of animals. PB and BB increased liver weights and significantly enhanced the development of hepatocellular foci and hepatocellular adenomas at 52 weeks and hepatocellular foci, hepatocellular adenomas, and trabecular carcinomas at 78 weeks in DENA-treated rats. No such enhancing effects were observed with AB or BA. PB or BB did not significantly enhance the incidence of nonhepatic tumors at 52 weeks. However, at 78 weeks BB significantly enhanced the development of renal tubular adenomas and carcinomas, while PB enhanced the development of thyroid follicular cell neoplasms in DENA-treated rats. These results clearly showed that barbiturates exhibited structure-promoting activity relationships and that their promoting abilities were not restricted to liver alone. Substitution of both hydrogen atoms at the C-5 position of the pyrimidine ring by alkyl or aryl groups appears to be essential but not sufficient for tumor-promoting activity of barbiturates.

Amobarbital↗
PubMed1978

Histocompatibility difference between C3HfeB/HeN and C3H/HeN mice: tumour induced in C3HfeB/HeN mice expresses C3H/HeN-associated alloantigen.

A transplacentally induced lung tumour of C3HfeB/HeN mouse origin expresses, as a tumour-associated antigen, a normal tissue component of strain A mice. The genetic locus coding for this alloantigen has been shown to be linked to the H-2 major histocompatibility complex. In the present study we demonstrate that this antigen is also expressed on normal tissues of C3H/HeN mice. Skin grafts exchanged between C3HfeB/HeN and C3H/HeN mice are reciprocally rejected at approximately 3 weeks after grafting. C3HfeB/HeN mice were derived from C3H/HeN mice in 1945. These strains have apparently deviated since then in their genetic regulation of the expression of the MHC-linked genetic locus. The finding of the C3H/HeN-associated antigen on a C3HfeB/HeN mouse-derived lung tumour indicates that this deviation is reversible.

Animals↗
PubMedDate not supplied

DNA adducts in human and patas monkey maternal and fetal tissues induced by platinum drug chemotherapy.

Platinum-DNA adducts in placenta and blood from a woman exposed to 200 mg/m2 of cis-diamminedichloroplatinum(II) (cisplatin) and 300 mg/m2 diamminecyclobutanedicarboxylatoplatinum(II) (carboplatin) for ovarian cancer have been documented by cisplatin-DNA enzyme-linked immunosorbent assay (ELISA) and atomic absorbance spectrometry (AAS). A patas monkey model was used to investigate transplacentally induced cisplatin-DNA damage in fetal tissues. During the last trimester of gestation, 5 patas monkeys were given multiple doses of cisplatin to mimic human ovarian cancer treatment. In spite of careful choice of dose and treatment conditions, cumulative toxicity occurred in monkeys given doses comparable on a mg/m2 basis to those received by the human. A total dose of 12 mg/m2 (0.625 mg/kg body weight), given in the last trimester, supported fetal viability, and multiple tissues, taken by cesarean section, were examined in the fetal monkeys. By cisplatin-DNA ELISA and AAS, maternal tissues from the monkey receiving the highest dose contained approximately twice as much DNA damage as the fetal tissues. A similar relationship was observed when we compared DNA adduct formation in fetal liver and biopsies of liver taken from the monkey dams at cesarean delivery. In all of the monkey pairs studied there were very significant levels of DNA damage in the placenta, and high adduct levels in brains of fetuses that survived treatment. Thus, cisplatin does cross the placenta in the patas monkey. These observations imply that the human fetus, for which the total maternal dose was approximately 5.4 mg platinum drug/kg body weight, may also have sustained some DNA damage.

Adult↗
PubMedDate not supplied

Transplacental cisplatin exposure induces persistent fetal mitochondrial and genomic DNA damage in patas monkeys.

A previous attempt to model transplacental cisplatin exposure and genotoxicity employed several pregnant Erythrocebus patas monkeys; most of the animals were exposed near the end of gestation and cisplatin-DNA adduct analyses included only genomic DNA. Here, both genomic and mitochondrial DNA adduct formation have been determined in fetuses from two pregnant monkeys exposed at the end of the second trimester of gestation. Multiple fetal tissues were obtained after doses of 0.315 mg cisplatin/kg body weight (5.3 mg/m2 total) on days 101 and 106 of gestation. Cesarean sections were performed 24 h after exposure and 27 d after exposure. Cisplatin genomic (g)-DNA adducts were observed in fetal adrenal, brain, heart, kidney, liver, skin, spleen, and thymus. When placentas from the two animals were divided into four concentric regions at increasing distances from the umbilical cord, and g-DNA was assayed, cisplatin DNA adduct levels were similar in all four regions. Mitochondrial (mt)-DNA adducts were higher than g-DNA adducts in maternal liver and fetal liver, brain and kidney, suggesting that the mitochondria may constitute a particular target for cisplatin genotoxicity. The study demonstrates significant fetal genotoxicity in g-DNA and mt-DNA of patas monkeys exposed to cisplatin in utero, suggesting that similarly exposed human fetuses may also sustain drug-induced DNA damage.

Animals↗