摘要:

AbstractTransplacental carcinogenesis is surveyed with emphasis on major problems currently constituting active areas of research. These include identification of transplacental carcinogens and the tissues they preferentially affect in different species; enzyme‐mediated metabolism of carcinogens; formation of reactive metabolites in maternal, placental, and fetal tissues; transplacental passage of carcinogens and their localization in fetal tissues; changing susceptibilities of different tissues during embryonic and fetal development; differences in susceptibility to a given agent between corresponding tissues of fetus and adult; carcinogenic effects in later generations not directly exposed to carcinogens in utero; tissue culture systems for identification of transformed cells used in combination with transplacental exposure to carcinogens; and relevance of animal experiments to cancer in man, including the special case of cancer in childhood and the possible interaction of teratogenic and carcinogenic agent

ISSN:0040-3709    

DOI:10.1002/tera.1420080202

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractMidsagittal sections of the heads of day 14.5–15.0 control A/J mouse fetuses revealed three areas of rapidly growing cartilage in the cranial base:mesethmoid, presphenoid, and craniopharyngeal. There was a curvature in the presphenoid, which straightened by the time of palatine shelf movement In fetuses of females treated with 6‐aminonicotinamide (6‐AN) on gestation day 13 the presphenoid had not straightened by day 15.5 and these fetuses all had cleft palate. In nontreated mice with spontaneous cleft lip and palate the presphenoid straightening was not impaired. Autoradiographs of [3H] thymidine uptake in the cranial base of experimental fetuses revealed selective impairment of cell proliferation in the presphenoid as judged by a significant decrease in labeled nuclei. It is proposed that straightening of the presphenoid is necessary for palatine shelf movement and normal palate cl

ISSN:0040-3709    

DOI:10.1002/tera.1420080203

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractThirty milligrams of hydrocortisone administered im to pregnant golden hamsters at gestation day 10:20 (i.e., 10 days, 20 h postconception), 11:00, or 11:04 produced 91, 100, and 100% cleft palate, respectively. Smaller doses (15, 20, or 25 mg) produced higher incidences of cleft palate at day 11:00 than 10:20 or 11:04, indicating that day 11:00 is the optimal time for yield of cleft palate with this system.

ISSN:0040-3709    

DOI:10.1002/tera.1420080204

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractIntraperitoneal administration of acetazolamide to pregnant female mice on day 9 or 10 of gestation (750 mg/kg given twice, at 10 AM and 4 PM) produced postaxial abnormalities of the forelimbs with high frequency in the CBA/J and C57BL/6J strains, intermediate frequency in A/J and DBA/2J, and low frequency in C3H/HeJ and SWR/J. CBA/J was most susceptible to treatment on day 10, A/J on days 9 and 10, and C57BL/6J and C3H/HeJ on day 9. There was no reduction in amount of amniotic fluid 4 h after the last injection.

ISSN:0040-3709    

DOI:10.1002/tera.1420080205

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractInfection with the H‐1 strain of parvovirus results in death and deformities in hamster embryos, retardation of skeletal growth and development in immature hamsters, and delayed repair of osseous wounds in older animals. Several aspects of this interference with bone growth can be reproduced as a laboratory model by infection of organ cultures of fetal hamster tibiae with H‐1 virus. To investigate the pathogenesis of this virus‐induced retardation of skeletal growth, the incorporation and release of35S by infected and control tibiae was measured in this organ culture model to determine the effect of H‐1 virus infection on the rates of synthesis and loss of mucopolysaccharides by fetal bone. Ash weights and mineral‐free dry weights of infected and control bones were also compared to detect differences in degrees of mineralization and cartilage formation. By these methods, growth retardation was found to be associated with decreased cartilage formation and increased synthesis and loss of mucopolysaccharides or their components. No difference was found between the mineral contents of infected and control bones. It is proposed that H‐1 virus infection interferes with formation of the matrix of cartilage and that intensified35S incorporation reflects a compensatory but ineffective effort to reverse this inhibition by increasing mucopolysaccharide synthesis. Although no quantitative difference was detected between the mineral contents of infected and control bones, it is suggested that disordered matrix formation may contribute to the delayed or incomplete mineralization of osseous tissues that occurs during later stages of maturation in this animal model of virus‐ind

ISSN:0040-3709    

DOI:10.1002/tera.1420080206

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractCortisone has long been used experimentally to induce cleft palate in mice, but the mechanisms by which it causes this effect remain controversial. It has been repeatedly demonstrated that after administration of cortisone the movement of the palatal shelves from a vertical to a horizontal position is delayed. The long‐accepted hypothesis is that during this delay growth of the head continues so that when the palatal shelves finally do become horizontal they are too far apart to meet in the midline and fuse. We found that maternally administered cortisone induced 95% cleft palate in ICR/DUB mouse fetuses observed at days 15–18 of gestation. Observations made on frozen, cryostat‐cut sections of fetal heads during the time of palate closure indicated that shelf elevation in experimental animals was delayed by as much as 12–14 h. However, when the shelves finally reached the horizontal they made contact with both the nasal septum and each other. It seems therefore that cortisone, beside causing delay in self movement, may also interfere with processes that occur subsequent to horizontalization leading to shelf

ISSN:0040-3709    

DOI:10.1002/tera.1420080207

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractThalidomide was taken by 113 pregnant women during August 1959 to December 1961. Of these, only seven women took the drug during the critical period, i.e., between the 34th and 50th day after the last menstrual period. Three of them delivered malformed babies, including one spontaneously aborted by the 101st day after the last menstrual period. The remaining four women had children without apparent malformations. Two of the four children were reexamined by the age of 11 years. Rentgenograms were taken of the entire skeleton, and no malformation attributable to thalidomide was found. The first day of thalidomide intake in these four cases ranged from the 46th–49th day after the last menstrual period. It seems that a “thalidomide‐resistant pregnancy” occurred in some of the cases in which the drug was taken only by the 46th day or later in the critical period. In the case of two other women, thalidomide was taken earlier than the critical period: one by the 19th day and the other by the 23rd. The former underwent an induced abortion, and the latter had a spontaneous abortion by the 49th day. In the remaining 104 cases, in which thalidomide was prescribed later than the critical period, the offspring were apparently normal, except for one case of anal s

ISSN:0040-3709    

DOI:10.1002/tera.1420080208

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractImplantation of 20‐methylcholanthrene (MC), 3,4 benzopyrerne (BP), and 7,12‐dimethylbenz [a] anthracene in the tail ofBufo arenarumtadpoles induced toratogenic effects as well as lymphocyte or pleomorphic cell nodule formation. The development of nodules was modified by a regenerative field. The incidence and intensity of the teratogenic effects (supernumerary fins, accessory notochords—the latter reported here for the first time in amphibia) were enhanced by a regenerative field caused by tail amputation. MC and BP produced only supernumerary fins, and did so infrequently; whereas DMBA produced both defects, and in relative large freque

ISSN:0040-3709    

DOI:10.1002/tera.1420080209

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

AbstractPregnant Long‐Evans rats were fed a synthetic diet lacking folic acid and containing 9‐methylpteroylglutamic acid on the llth day of gestation and then fed a complete diet beginning on the 14th day. Treated and untreated pregnant rats injected with 10 μCi of [14C] ethanolamine on the 12th or 14th day of gestation were killed on the 14th, 15th, or 16th day. The total radioactivity and radioactivities of phosphatidylethanolamine (PE), phosphatidylcholine (PC), and lysophosphatidylethanolamine (LPE) were determined in chloroform extracts of homogenates and subcellular fractions prepared from whole emhryos on the designated days of gestation. The specific radioactivity of phospholipids extracted from the lysosomal‐rich fraction of treated embryos was twice that of controls but the phospholipid‐specific radioactivity of the low‐speed fraction from treated embryos was one‐half of that of controls on the 14th day. The relative distribution of radioactivity in PE and PC extracted from subcellular organelles of either treated or untreated embryos suggested a precursor‐product relation. The conversion of radiolabeled PE to PC seemed to occur faster in almost all subcellular fractions of the treated embryos and did not occur in the same temporal order from fraction to fraction as was found for untreated embryos. These data were interpreted to mean that the teratogen (1) stimulated lysosomal synthesis and depressed nuclear synthesis, (2) perturbed intraembryonic transmethylation of PE to lecithin, perhaps shifting the embryo to a greater dependence on placental metabolism or transport, and (3) disturbed the chemical composition of various intraernbryonic subcell

ISSN:0040-3709    

DOI:10.1002/tera.1420080210

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY

摘要:

Abstract5‐fluoro‐2'‐deoxycytidine (FCdR) was administered ip to pregnant ICR‐JCL mice on days 7 to 12 of pregnancy either at a single dose of 1.5 mg/kg orfive fractionated doses of the same total amount at 3‐h intervals. The fraction‐ ated injections resulted in much stronger teratogenic effects than single injectionon days 9, 10, and 11 of pregnancy. Embryocidal effects of fractionated injections were more severe than single injection on days 9 and 10 of pregnancy. The mal‐formation frequency produced by fractionated injection was at least equivalent to single doses of 7.5 mg/kg when the drug was given on day 9

ISSN:0040-3709    

DOI:10.1002/tera.1420080211

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1973

数据来源: WILEY