Chlorambucil-induced abnormalities of the urogenital system of rat fetuses

Pattern of Response of Intact Drosophila to Known Teratogens

Drosophila, as the test organism, was used to assess 17 chemicals. The teratogenic potential of 15 of these chemicals is well established from animal studies or human epidemiology. The test involves examination of adult flies following treatment during larval stages of development. Flies are examined for abnormal external morphology. The incidence of abnormalities in treated and control populations is compared using the Chi-square test. All 17 chemicals were active to varying degrees in the test system. Most chemicals produced a unique response yielding individual patterns of abnormalities. These results suggest that Drosophila may have the potential to become a valuable teratogen screen, but further, more rigorous examination–particularly with nonteratogens–is required.

Human pregnancy safety for agents used to treat rheumatoid arthritis: adequacy of available information and strategies for developing post-marketing data

For female patients with rheumatoid arthritis, the availability of a host of new disease modifying antirheumatic drugs has raised important questions about fetal safety if a woman becomes pregnant while she is being treated. In addition, there is limited safety information regarding many of the older medications commonly used to treat rheumatoid arthritis in women of reproductive age. Current summary pregnancy risk information for selected medications used to treat rheumatoid arthritis is reviewed in the context of the pregnancy label category. In addition, the strengths and weaknesses of post-marketing strategies for developing new pregnancy safety information are described.

High prevalence of ectopic kidney in Coast Province, Kenya

OBJECTIVE

To establish the prevalence of congenital urinary tract abnormalities in a full population-based ultrasound survey of an area of coastal Kenya.

METHODS

Ultrasound examination of 3118 residents of 912 households, including all available subjects over 2 years of age, residing in five contiguous rural villages 50 km south of Mombasa.

RESULTS

Survey findings indicated simple renal ectopia in 11 of 3118 subjects (0.35%) and renal agenesis in three (0.096%). No cases of horseshoe kidney or complex urinary anomaly were detected, and no cases of multiple congenital anomaly were found. Ectopia cases were evenly distributed between men and women, and across the five study villages. None of the individuals affected by renal ectopia were closely related (i.e. <5th-degree relations).

CONCLUSION

There is an unusually high prevalence of ectopia among unrelated subjects in this area. In this setting, the findings suggest either a common exposure to teratogenetic factors, or a hereditary condition with variable penetrance, where more severely affected individuals are not observed because of foetal/infant mortality.

Immunosuppressive drug use during pregnancy

Women with rheumatic diseases frequently need treatment throughout pregnancy and lactation. Physicians must confront the dual challenge of monitoring the possible effects of the underlying maternal disease and the medications on both mother and child. It is essential that the maternal disease be well controlled before, during, and after pregnancy to ensure the best possible outcome for the mother and child. Corticosteroids have been used extensively and safely in pregnant patients with systemic lupus erythematosus and rheumatoid arthritis; there have been no reports of congenital malformations in the exposed infants. There is considerable experience using azathioprine during pregnancy if the maternal condition requires use of a cytotoxic drug; there has been no increased risk of congenital malformations in the exposed infants. There is limited information on the safety of other medications, including 6-mercaptopurine, cyclophosphamide, and cyclosporine. Methotrexate is contraindicated during pregnancy, and chlorambucil should be avoided because there are other effective immunosuppressive agents available for use. Corticosteroids (prednisone and methylprednisolone) can be used safely during lactation. All other immunosuppressive medications, azathioprine and 6-mercaptopurine, chlorambucil, cyclophosphamide, cyclosporine, and methotrexate, are contraindicated during lactation.

Evaluation of the embryotoxic potential of ten chemicals in the whole mouse embryo culture

Ten widely different chemicals, actinomycin D, mithramycin, podophyllotoxin, vincristine sulfate, triaziquone, chlorambucil, mercaptopurine riboside, methyl-mercaptopurine riboside, dimethylsulfoxide, and L-lysine were tested in the whole mouse embryo culture system. The highest concentration was always the concentration that induced 100% lethality (ELC100). The lowest concentration varied from 1/2 to 1/10 of the ELC100. The chemicals that had the most noxious effect on embryonic growth and differentiation were actinomycin D, triaziquone, and mercaptopurine riboside. Podophyllotoxin, methyl-mercaptopurine riboside, and L-lysine were the less embryotoxic. As a whole, no significant discrepancies were observed between the results and the teratological data obtained from the literature. These observations support the assumption that the whole murine embryo culture system can give valuable information on the teratogenicity of chemicals.

Critical prenatal periods for chlorambucil-induced functional alterations of the rat kidney

Previous studies have demonstrated that exposure of rats to chlorambucil during the period of metanephric differentiation results in morphological and functional alterations of the kidneys after birth. The present study describes the effects of chlorambucil treatment at various gestational ages on neonatal renal function to determine if critical periods other than day 11 exist for inducing functional developmental toxicity of the kidneys. Groups of pregnant Sprague-Dawley rats were exposed to 4.5 mg/kg of chlorambucil on gestation days 9, 11, 13 or 15 and the offspring were evaluated for neonatal growth and viability, gross malformations of the kidneys, and renal physiology. The results demonstrate that the critical period for the induction of specific renal defects and hypoplasia lies on day 11 of gestation, but functional alterations of the kidneys were observed after exposure on day 15 of gestation. In terms of practical application, a combination of the basal clearance test and the renal concentration test together provide an efficient means for detecting prenatally induced functional alterations of the kidneys. When renal malformations or anomalies are observed in standard teratology bioassays, studies using techniques similar to those described here may be extremely useful in determining the biological significance as well as permanence or transience of effects such as renal hypoplasia, dilated renal pelvis, and dilated ureter.

Chlorambucil induced congenital renal hypoplasia: effects on basal renal function in the developing rat

Administration of chlorambucil to pregnant rats on day 11 of gestation induced dose-related alterations in renal growth and function in the postnatal offspring. These effects occurred above and beyond the reductions in body growth and were evident in animals that displayed no overt malformation of the urogenital tract. Reductions in overall growth amounted to 0, 6 and 15% in the 3,4.5 and 6 mg/kg groups, respectively, while kidney weights were reduced by 7, 15 and 23%. The weights of the kidneys relative to the body were reduced 5, 9 and 10% with increasing dose. Although basal renal function was not affected by the degree of hypoplasia seen in the low dose group, reduced glomerular and tubular function were evident following a basal clearance test in the 2 highest dose groups. The data indicate that chlorambucil induced renal hypoplasia results in reductions in renal function that persist for at least the first 3 weeks after birth in the rat and that physiological assessment of developmental toxicity can provide an extremely useful addendum to the more classical morphological criteria.

A selection of candidate compounds for in vitro teratogenesis test validation

The Consensus Workshop on In Vitro Teratogenesis Testing recommended that test validation be facilitated by a listing of agents with defined teratogenicity; subsequently, a panel was convened to review and select such agents. This communication established a list of 47 compounds or conditions which demonstrate a wide range of teratogenicity in vivo. The agents were chosen primarily on the strength of the literature base denoting their in vivo effects. The tables note a number of general biological and toxicological characteristics for each agent, and the details of representative in vivo teratology studies are summarized and referenced. This list is intended to serve as a base for in vitro teratogenesis test validation and should prove useful in developing and identifying those systems which will contribute to a more effective testing program.

Morphometric, biochemical, and physiological assessment of perinatally induced renal dysfunction

Three chemicals, known either to alter renal development when administered during fetal development or to affect renal function when administered to adult rats, were administered to Sprague-Dawley rats at critical periods of renal development. Chlorambucil (CHL) was administered ip on d 11 of gestation at doses of 0, 3, and 6 mg/kg; nitrofen (2,4-dichlorophenyl p-nitrophenyl ether) (NIT) was given po on d 8-16 of gestation at 0, 4.17, 12.5, and 25 mg/kg . d; and mercuric chloride (MER) was given sc on postnatal d 1 at 0, 14, and 28 micrograms/pup. To assess the effects of these toxicants on the functional development of the kidneys, a diuresis test with and without antidiuretic hormone was applied on postnatal d 3 (PD 3); a hydropenia test on PD 6; and kidney weights, glomerular counts in midhilar cross sections, and the specific activity of renal alkaline phosphatase were determined on PD 3 and 6. Data from pups with obvious malformations of the kidneys was eliminated from the statistical analyses of the data so that emphasis could be placed on alterations of functional development in individuals with apparently morphologically normal kidneys. CHL retarded the growth and biochemical differentiation of the kidney at 6 mg/kg. Pups from this treatment groups showed an attenuated response to exogenously administered antidiuretic hormone. NIT impaired growth and altered renal morphology at a dose of 12.5 mg/kg . d and altered physiological responses in the absence of anatomical changes at a dose of 4.17 mg/kg . d. MER, at doses near the maximum tolerated, failed to alter any parameter, indicating that the very young animal differs markedly from the adult in response to that compound. The data indicate that relatively simple tests of renal function are useful in the detection of perinatally induced nephrotoxicity.

An analysis of fetotoxicity using biochemical endpoints of organ differentiation

The biochemical differentiation of the brain, lungs, liver, and kidneys of the late gestation rat fetus was examined to characterize the immediate implications of retarded growth on fetal development. Initially, the normative profile of development of the brain (weight, DNA content, and protein content), lungs (weight and surfactant accumulation), liver (weight and glycogen deposition), and kidneys (weight, alkaline phosphatase activity, and protein content) was determined on gestation days 19, 20, 21, and 22 (day 1 = finding of sperm in the vaginal smear). Subsequently, five compounds known to induce fetotoxicity (chlorambucil, methyl salicylate, mirex, nitrofen, and toxaphene) were administered during organogenesis, and the effects on organ differentiation were determined in day 21 fetuses. The effects of fetal growth retardation resulting from exposure to exogenous agents were not equally distributed among the organs studied. The liver and kidney appeared more sensitive to insult by these agents than did the brain and lungs.

Marrow neutrophil reserve after adjuvant chemotherapy for carcinoma of the breast

The hematologic factors of 16 female patients with breast carcinoma who had received adjuvant chemotherapy with L-phenylalanine-based programs for two years were compared with those for 13 normal female volunteers of similar age. The findings include significant suppression of the mean hemoglobin level, of leukocyte counts, and of circulating neutrophils and lymphocytes in patients 3-27 months after chemotherapy. Marrow neutrophil reserve studies with prednisolone stimulation again demonstrated significant suppression for the patients who had received chemotherapy. The authors conclude that there is a chronic hematologic toxicity associated with this therapy.

Correlation between the growth inhibitory effects, partition coefficients and teratogenic effects of lipophilic acids

The inhibition of cell duplication by many lipophilic acids was measured in Bacillus subtilis and in the following mammalian cell lines, the human epithelial-type cell lines HeLa, strain R and strain L-132, the human fibroblast cell line VA-13, and the rat glial cell line C. The results were correlated to the partition coefficient and the distribution coefficient (= apparent partition coefficient at pH 7.2) of the compounds, using octanol/water partition coefficients and pKa values either from the literature or measured for this work. For B. subtilis, the logarithm of the inhibitory potency of most compounds increases linearly with the logarithm of the partition coefficient. Exceptional high potencies were observed for compounds that can efficiently delocalize the charge of the negative ion over the whole molecule. Most compounds inhibit tissue cultures at least as potently as they inhibit B. subtilis. But some compounds are significantly more potent in tissue cultures than would have been expected from the B. subtilis data; such compounds (analgesics/antipyretics, anti-inflammatory compounds, butyrate, norepinephrine) presumably inhibits mammalian cells by specific reactions with certain cell components. However, most compounds inhibit the different cell lines to a similar degree, indicating no cellular specificity; exceptions to this rule are chlorambucil, chlortetracycline and dexamethasone. Many of the lipophilic acids that are potent inhibitors of mammalian cell replication are also teratogenic. Exceptional compounds may not reach the embryo. We propose that a number of other lipophilic acids that are potenta inhibitors and to which humans are frequently exposed should be tested for their teratogenic effect.

Arsenate-induced renal agenesis in rats

The developmental origin of arsenate-induced renal agenesis was investigated. Pregnant Wistar rats were each injected once ip with 45 mg/kg sodium arsenate at day 10 (sperm day = day 0). Pregnancy was terminated at various times following injection and the embryos recovered and serially sectioned. Renal agenesis resulted when the mesonephric duct failded to give rise to a ureteric bud with subsequent failure of induction of the metanephric blastema. The underlying defect was retardation in growth of the mesonephric duct, first observed 48 hours after arsenate injection. A shortened mesonephric duct also resulted in a failure of the mesonephros to attain normal size and in the male resulted in absence of the ductus deferens, seminal vesicle a variable portion of the epididymis. Due to the intimate association of the mesonephric and growing paramesonephric ducts, a shortened mesonephric duct resulted in a shortened paramesonephric duct with resultant lack of a uterine horn.

Urogenital anomalies in fetal rats produced by the anticancer agent 4(5)-(3,3-dimethyl-1-triazeno) imidazole-4-carboxamide

Pregnant Wistar rats injected intraperitoneally on gestational day 12 with single doses (100-1,000 mg/kg) or 600 mg/kg of 4(5)-(3,3-dimethyl-1-triazeno) imidazole-4-carboxamide (dic) were autopsied on day 21 (100-1,000 mg/kg) or at 24-hour intervals on days 13-20 (600 mg/kg). Controls received CMC on the same schedule. All fetuses were weighed and examined for urogenital system (UGS) malformations. Those given 600 mg/kg were also studied histologically. DIC produced significant growth retardation at all doses on day 21 (18-72%). UGS malformations occurred in 27-67% of the fetuses at 200-400 mg/kg and in 100% of those given 600 mg/kg or more of DIC. Abnormalities included renal growth inhibition, fusion, ectopia, and ureteropelvic dilatation. At 600 mg/kg renal and body weights were reduced 40 and 55%, respectively. Ureteropelvic dilation was common, and cortical glomeruli, nephric collecting tubules, and papillae were retarded in development. The juxtamedullary glomeruli were well developed. Proximal nephric tubular mitotic activity was 85% greater than in control animals (day 17). On the basis of pertinent morphological and physiological data, it is postulated that the dilated upper urinary tracts represent functional hydronephrosis incident to severe renal retardation and its resultant compensatory response.

Teratogenic effects of chlorambucil on in vivo and in vitro organogenesis in mice

Pregnant ICR/DUB mice were each given a single oral injection of chlorambucil (14.2 or 20 mg/kg) on the 10th, 11th, 12th, or 13th day of gestation (plug day = 1st day). Fetuses examined on the 18th day were decreased in weight and had tail, cranial, and limb defects. They type and frequency of malformations differed according to the dosage and day of treatment. Limb defects resulted from treatment on the 11th or 12th days of gestation and tail defects from treatment on all days. Control limb buds from 12th day embryos cultured for 6 days in serum-supplemented BGJ medium containing 0.5-2 mug/ml chlorambucil were retarded in development and had cartilage abnormalities. The extent of the deformities was dose related. Limb buds were also taken from embryos 24 h after in vivo exposure to teratogenic doses of chlorambucil and cultured in control medium. After 6 days in culture these limbs also had growth impairment and cartilage abnormalities. The defects in limbs exposed in vitro were similar to those in limbs exposed in vivo.

Renal ectopia and fusion. Embryologic Basis

To determine when horseshoe kidneys and crossed fused ectopic kidneys might develop, the authors studied the Carnegie collection of human embryos. They found that renal fusion must occur before the kidneys ascend between the umbilical arteries.