Bovine-derived hemoglobin-based oxygen carriers (HBOCs) have been investigated for use in humans (HBOC-201) and approved for veterinary medicine (HBOC-301). We infused pregnant beagles with HBOC-201 to test whether HBOC-induced developmental toxicity previously observed in rats would occur in a species devoid of an inverted visceral yolk sac (invVYS). Phase 1 assessed developmental toxicity of 6g/kg HBOC-201 on gestational day (GD) 21. Phase 2 investigated single infusions of 6g/kg HBOC-201 on one of GDs 21, 25, 29 or 33. Phase 3 studied multiple sequential infusions on GDs 21, 23,25,27,29, 31, and 33 at 0.52g/kg/day (3.6g/kg total dose). Mild to moderate maternal toxicity occurred in all phases. There was an unequivocal absence of developmental toxicity in all phases. Overall, our hypothesis that HBOC, which interferes with the function of the invVYS, would not affect the offspring in dogs was supported. The implications relative to human risk are discussed.

HBOC-201 is a bovine-derived, cross-linked, and stabilized hemoglobin (250 kDa) in physiological saline. Daily intravenous infusions of HBOC (1.95, 3.90, or 5.85 g/kg/day) during gestational days (GDs) 6-18 in Sprague-Dawley rats caused fetal mortality, reduced birth weight, and malformations. Subsequent single-day infusions (5.85 g/kg/day) showed that developmental toxicity was limited to GDs 7-9 when histiotrophic nutrition via the inverted visceral yolk sac (invVYS) is essential. Histiotrophic nutrition is receptor-mediated endocytosis of bulk maternal proteins and subsequent lysosomal degradation providing amino acids and other nutrients for embryonic growth. Controls for protein content, oncotic properties, and hemoglobin content indicated that toxicity was due to hemoglobin. Rat whole embryo cultures verified HBOC interference with invVYS transport capacity and resultant deficient embryonic nutrition. These mechanisms of action are not expected to impact human development based on differences in VYS morphology and function, although a complete understanding of early human embryonic nutrition is lacking. (C) 2015 Published by Elsevier Inc.

This chapter reviews historical and current trends in the evaluation of a male reproductive toxicant. This evaluation encompasses the design, conduct and interpretation of studies evaluating alterations in the structure and function of male reproductive organs. While the primary objective of any reproductive toxicity study is to quantitate reproductive outcome, newer investigators are often faced with challenging questions regarding the choice of endpoints and thus some of the important aspects of study design are discussed. The first half of this chapter discusses standard approaches and regulatory guidelines governing the timing and design of these studies. The latter half of the chapter discusses current methodologies for evaluating effects on male reproductive health, including functional assessments of spermatogenesis and fertility, along with gross macroscopic and microscopic evaluations. In addition, toxicant-induced effects on the developing male and aspects of male-mediated developmental toxicity are presented. Finally, data interpretation and the importance of evaluating the weight of the evidence are emphasized in the evaluation of a male reproductive toxicant.

Birth Defects Research Part A: Clinical and Molecular TeratologyVolume 76, Issue 5 p. 313-340 Platform Session Abstracts Teratology Society Platform Session Abstracts First published: 17 May 2006 https://doi.org/10.1002/bdra.20261Citations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume76, Issue5May 2006Pages 313-340 RelatedInformation

The potential for nelfinavir mesylate (VIRACEPT) to produce reproductive toxicity was evaluated in rats administered oral doses of 200, 500, or 1000mg/kg/day. In the fertility and early embryonic development to implantation study, male rats were treated beginning 28 days prior to mating until necropsy and females for 2 weeks prior to mating and through gestation day (GD) 7. In the pre- and postnatal development study, pregnant rats were treated from GD 6 through lactation day (LD) 20. Selected F(1) pups from this study were evaluated in sensory and behavioral tests and were subsequently mated. Pregnant F(1) females were euthanized on GD 20 and their F(2) fetuses were examined. F(1) animals were not directly dosed with the drug. No treatment-related effects were observed on any male reproductive parameters. Administration of nelfinavir did not produce adverse effects on fertility, pregnancy, embryo-fetal development, parturition, or lactation in the F(0) generation. Similarly, no adverse effects of nelfinavir treatment were observed on pre- and postnatal growth, development, reproductive performance and embryo-fetal development in the F(1) offspring. Based on the results of this study, the no-observed-adverse-effect-level (NOAEL) for developmental and reproductive toxicity in rats was considered to be 1000mg/kg/day, the highest dose tested.

The potential for nelfinavir mesylate (VIRACEPT) to induce maternal and embryo-fetal toxicity was evaluated in rats and rabbits following oral administration. The drug was administered by gavage to rats at doses of 200, 500, or 1000mg/kg/day on days 6-17 of gestation and to rabbits at doses of 200, 400, or 1000mg/kg/day on days 7-20 of gestation. Dams and does were euthanized on GD20 and 29, respectively, and the offspring were weighed and examined for external, visceral, and skeletal alterations. Maximum plasma nelfinavir concentrations (C(max)) in rats were comparable to C(max) values in humans and were 3- to 6-fold higher than the reported human trough levels, while plasma nelfinavir levels in rabbits were approximately 0.13-0.17x the human C(max) and 0.25-0.5x the human trough. In rats, no treatment-related maternal or embryo-fetal toxicity was observed at any dose level and the NOAEL for both maternal and fetal toxicity was considered to be 1000mg/kg/day. Two rabbits in the 400mg/kg/day group died prior to scheduled termination. Because no deaths occurred in the high dose group and there were no other treatment-related signs of clinical toxicity in any dose group, these deaths were considered unrelated to nelfinavir. Group mean body weight loss in rabbits was observed at 1000mg/kg/day on gestation days 7-10. Food consumption was also reduced in this treatment group throughout the dosing period. There were no treatment-related findings in other maternal or fetal parameters. Thus, the no-observed-adverse-effect-level (NOAEL) for maternal toxicity in the rabbit was considered to be 400mg/kg/day (based on maternal body weight loss in the high dose group), while the NOAEL for embryo-fetal toxicity in the rabbit was considered to be 1000mg/kg/day. Thus, under the conditions of this study, nelfinavir was not considered to be toxic to the rat or rabbit conceptus.

A thorough review of the literature revealed no published repeated-dose oral developmental toxicity studies of inorganic arsenic in rats. In the present study, which was conducted according to modern regulatory guidelines, arsenic trioxide was administered orally beginning 14 days prior to mating and continuing through mating and gestation until gestational day 19. Exposures began prior to mating in an attempt to achieve a steady state of arsenic in the bloodstream of dams prior to embryo-foetal development. Groups of 25 Crl:CD(SD)BR female rats received doses of 0, 1, 2.5, 5 or 10mg/kg/day by gavage. The selection of these dose levels was based on a preliminary range-finding study, in which excessive post-implantation loss and markedly decreased foetal weight occurred at doses of 15 mg/kg/day and maternal deaths occurred at higher doses. Maternal toxicity in the 10mg/kg/day group was evidenced by decreased food consumption and decreased net body weight gain during gestation, increased liver and kidney weights, and stomach abnormalities (adhesions and eroded areas). Transient decreases in food consumption in the 5mg/kg/day group caused the maternal no-observed-adverse-effect level (NOAEL) to be determined as 2. 5mg/kg/day. Intrauterine parameters were unaffected by arsenic trioxide. No treatment-related foetal malformations were noted in any dose group. Increased skeletal variations at 10mg/kg/day were attributed to reduced foetal weight at that dose level. The developmental NOAEL was thus 5mg/kg/day. Based on this study, orally administered arsenic trioxide cannot be considered to be a selective developmental toxicant (i.e. it is not more toxic to the conceptus than to the maternal organism), nor does it exhibit any propensity to cause neural tube defects, even at maternally toxic dose levels.

Assessment of risks to human health from chemical agents is a complex process that requires the assembly, careful analysis, and integration of human and animal data collected from studies performed at different times, for disparate purposes, and under varying conditions. The application of risk assessment methods to data without consideration of the relevance of critical experimental parameters such as route of exposure or magnitude of dose can lead to specious determinations of the risk posed by exposure to environmental agents. A case study of the purported risk of developmental toxicity from inorganic arsenic is presented to illustrate (1) the nature of the problem, (2) how extant data from all studies are useful, (3) how appropriately designed modern studies can clarify the situation, and (4) how conflicted data should be evaluated in terms of appropriateness for use in risk assessment.

A review of the literature revealed no published inhalational developmental toxicity studies of arsenic performed according to modern regulatory guidelines and with exposure throughout gestation. In the present study, inorganic arsenic, as arsenic trioxide (As(+3), As2O3), was administered via whole-body inhalational exposure to groups of twenty-five Crl:CD(SD)BR female rats for six h per day every day, beginning fourteen days prior to mating and continuing throughout mating and gestation. Exposures were begun prior to mating in order to achieve a biological steady state of As(+3) in the dams prior to embryonal-fetal development. In a preliminary exposure range-finding study, half of the females that had been exposed to arsenic trioxide at 25 mg/m3 died or were euthanized in extremis. In the definitive study, target exposure levels were 0.3, 3.0, and 10.0 mg/m3. Maternal toxicity, which was determined by the occurrence of rales, a decrease in net body weight gain, and a decrease in food intake during pre-mating and gestational exposure, was observed only at the 10 mg/m3 exposure level. Intrauterine parameters (mean numbers of corpora lutea, implantation sites, resorptions and viable fetuses, and mean fetal weights) were unaffected by treatment. No treatment-related malformations or developmental variations were noted at any exposure level. The no-observed-adverse-effect level (NOAEL) for maternal toxicity was 3.0 mg/m3; the NOAEL for developmental toxicity was greater than or equal to 10 mg/m3, 760 times both the time-weighted average threshold limit value (TLV) and the permissible exposure limit (PEL) for humans. Based on the results of this study, we conclude that arsenic trioxide, when administered via whole-body inhalation to pregnant rats, is not a developmental toxicant.

Numerous studies have suggested that single-day intraperitoneal (IP) injection of inorganic arsenic results in failure of neural tube closure and other malformations in rats, hamsters, and mice. Most of these studies involved treatment of limited numbers of animals with maternally toxic doses of arsenic (generally As(V)), without defining a dose-response relationship. In the present Good Laboratory Practice-compliant study, sodium arsenate (As(V)) was administered IP and arsenic trioxide (As(III)) was administered either IP or orally (by gavage) on gestational day 9 to groups of 25 mated Crl:CD(R)(SD)BR rats. Only at dose levels that caused severe maternal toxicity, including lethality, did IP injection of arsenic trioxide produce neural tube and ocular defects; oral administration of higher doses of arsenic trioxide caused some maternal deaths but no treatment-related fetal malformations. In contrast, IP injection of similar amounts of sodium arsenate (based on the molar amount of arsenic) caused mild maternal toxicity but a large increase in malformations, including neural tube, eye, and jaw defects. In summary, neural tube and craniofacial defects were observed after IP injection of both As(V) and As(III); however, no increase in malformations was seen following oral administration of As(III), even at maternally lethal doses. These results demonstrate that the frequently cited association between prenatal exposure to inorganic arsenic and malformations in laboratory animals is dependent on a route of administration that is not appropriate for human risk assessment.