Thomas F. Gale

Embryotoxic effects of chromium trioxide in hamsters

Chromium trioxide was administered iv at 5, 7.5, 10, and 15 mg/kg to pregnant golden hamsters early on the 8th gestation day. Fetuses were collected from the treated females on the 12th, 14th, and 15th gestation days and examined for the frequency and types of external, internal, and skeletal malformations. It is concluded that exposure of hamsters to this chemical form of a ubiquitous metallic element can kill fetuses in utero and produce edema and retardation as well as specific malformations in surviving fetuses. The most interesting malformations included cleft palate and defects in the ossification of the skeletal system. The results are discussed in relation to other teratogenic agents with particular emphasis on mechanisms of cleft palate formation.

A variable embryotoxic response to lead in different strains of hamsters

Lead nitrate was administered intravenously at 50 mg/kg to five inbred strains (MHA, LSH, LHC, CB, and P)4) and the non-inbred LVG strain of pregnant hamsters early on the 8th gestation day. All fetuses from treated and control hamsters were collected on the 15th gestation day and examined for the frequency and kinds of external, internal, and skeletal abnormalities. The major embryotoxic effects included resorptions, tail bud abnormalities, hydrocephalus, and skeletal defects. It is concluded that the LSH, LHC, LVG, and PD4 strains are susceptible while the MHA and CB strains are relatively resistant to the lead exposure.

The embryotoxic response produced by inorganic mercury in different strains of hamsters

Abstract This report compares the mercury-induced embryotoxicity among one noninbred (LVG) and five inbred (CB, LHC, LSH, MHA, PD4) strains of hamsters. A single dose of mercuric acetate (15 mg/kg, sc) was injected into pregnant hamsters on the morning of the 8th gestation day. Treated and control animals were killed on either the 12th or 15th gestation day and studied for the types and frequency of external and internal abnormalities as well as the incidence of resorption sites. The hamster strains exhibited significant resorption rates as well as a variety of abnormalities including edema, retardation, ventral wall defects, pericardial cavity distention, cleft palate, hydrocephalus, and heart defects. Significant but varied interstrain differences were observed for most of these indicators of mercury-induced embryotoxicity. The results of this study were compared with prior work in which the same hamster strains were exposed to cadmium or lead.

Effects of prenatal capsaicin treatment on fetal spontaneous activity, opiate receptor binding, and acid phosphatase in the spinal cord

Abstract Although the effects of capsaicin in neonatal and adult animals have been reported, the effects of prenatal capsaicin treatment are not known. We examined the teratologic and neurotoxic potential of capsaicin treatment in fetal rats. Capsaicin was injected into pregnant rats at various times during gestation. No gross external or internal malformations resulted. After injection on days 16 and 17 of gestation, a decrease in fetal spontaneous activity occurred as well as a loss of fetal responsiveness to morphine. This accompanied a loss of [3H]naloxone binding in the fetal spinal cord but not in the brain stem. [3H]Naloxone binding returned to normal by 24 days postnatally. Acid phosphatase, which normally appears in the substantia gelatinosa postnatally, was permanently reduced after capsaicin treatment at 16 and 17 days of gestation.

The embryotoxic response to maternal chromium trioxide exposure in different strains of hamsters

Abstract This paper compares the chromium trioxide-induced embryotoxic effects among one noninbred (LVG) and five inbred (CB, LHC, LSH, MHA, PD4) strains of hamsters. A single dose of chromium trioxide (8 mg/kg, iv) was injected into pregnant hamsters on the morning of gestation Day 8. Treated and control animals were killed on gestation Day 15 and studied for the types and incidence of external and internal abnormalities, as well as the frequency of resorption sites per uterus. The embryotoxic effects detected in this study include significant rates of resorptions, external abnormalities, cleft palate, and hydrocephalus. The results indicate that the MHA, LSH, and LVG strains are susceptible, while the CB, LHC, and PD4 strains are resistant to chromium trioxide-induced embryotoxicity. This study was compared with prior work in which the same hamster strains were treated with either cadmium, lead, or mercury.

Clinical anatomy of the popliteal blood vessels

The surgical management of venous injuries in the popliteal fossa is a contested issue. The basic options are ligation or repair. Most anatomy textbooks briefly describe a single popliteal vein, and the literature contains few references on venous patterns in this region. Although the primary objective of this study was to analyze venous variability in 52 dissected cadaveric popliteal fossae and 63 venograms, data were also collected on the popliteal artery. Nine groups (A–I) were designated regarding the manner of formation of the popliteal vein. These groupings were based primarily on differences in the union of the anterior tibial, posterior tibial, and fibular (peroneal) veins to form medial and lateral (popliteal) veins, and whether these two veins fused to form a singular popliteal vein proximal or distal to the transverse plane at the level of the distal edge of the femoral condyles (FC). In the majority of the dissections and venograms, multiple veins crossed the FC, and the medial vein was larger in diameter than the lateral vein. Two patterns of popliteal artery termination were observed based on differences in the site of origin of the fibular artery. The results were compared with anatomy and vascular surgery textbook descriptions and sparse literature reports on vascular variations in the popliteal fossa. It is hoped that these data will benefit surgeons performing procedures in this region. Clin. Anat. 13:347–353, 2000.

The amelioration of mercury-induced embryotoxic effects by simultaneous treatment with zinc

Prior work has demonstrated that inorganic mercury produces a number of toxic effects in embryos when this metal is administered to pregnant hamsters subcutaneously on the eighth gestation day. Also, treatment of various pregnant animals with zinc produces little evidence of embryotoxicity. The literature reveals that the simultaneous exposure of pregnant animals to different combinations of teratogenic and nonteratogenic agents produces variable responses which can be characterized as either protective or synergistic types of interactions. The purpose of this study was to determine the effect of subcutaneously injected combinations of zinc and mercury on the developing hamster embryo. The major conclusion drawn from this work is that the simultaneous maternal treatment with zinc and mercury ameliorates the harmful effects produced by treatment with mercury alone.

Toxic Effects of Cadmium and Amaranth on the Developing Hamster Embryo

The administration of a water soluble salt of the environmental contaminant, cadmium, is known to damage the developing hamster embryo. The major areas affected include the head, ribs and limbs; the area damaged is determined by the time of maternal exposure to this metal. The embryotoxic response produced by a single teratogen is often modified by the administration of combinations of two teratogens or a teratogen and a non-teratogen. For example, cadmium-induced cranial abnormalities are prevented by the simultaneous treatment with lead. Also, treatment with the nonteratogen, zinc helps protect the embryo from the detrimental effects of mercury administration. The purpose of the present study was to determine whether the maternal exposure to both amaranth and cadmium would alter the known embryotoxic effects of cadmium on the developing embryo.

Absence of correlation between transient cranial hemorrhages and congenital malformations following neural crest ablation in chicks

Ablation of premigratory cardiac neural crest has been used to produce and study extensively a model of abnormal cardiovascular dysmorphology. Previous and continuing research in this laboratory concerns different aspects of the involvement of cranial neural crest in the development of cranial, cervical and cardiac tissues in chick embryos. Recently, we detected the occurrence of transient cranial hemorrhages 24-48 hr after the ablation of selected segments of premigratory cranial neural crest. Since one possible mechanism of action for certain teratogens involves nonreparable damage to a primordial embryonic tissue by an antecedent hemorrhage, the objective of this study was to determine which of three different neural crest ablations is associated with hemorrhages and whether subsequent congenital abnormalities were correlated with the ablation procedure and/or hemorrhage. Premigratory neural crest was ablated from 3 different sites, designated cardiac, mesencephalic and trunk crest, respectively, of stage 8-10 chick embryos. Sham-operated embryos were controls. At 24, 30, and 48 hr after ablation, each embryo was observed for the presence of hemorrhages. On incubation day 11 all the living embryos were killed, fixed, weighed, and analyzed for selected length measurements, developmental stage, and the types and rates of congenital abnormalities. Cardiac and mesencephalic ablation group embryos exhibited significant incidences of cranial hemorrhages and changes in many of the parameters analyzed. It was concluded that the cardiac and mesencephalic, but not the trunk neural crest ablations, produced significant changes in incubation day 11 embryos. However, there was no correlation between the abnormalities and the prior occurrence of the transient cranial hemorrhages.

The effect of mercuric acetate on selected enzymes of maternal and fetal hamsters at different gestational ages

This study establishes levels of activity of glucose-6-phosphate dehydrogenase (G6PD), glycogen phosphorylase (GP), and cytochrome c oxidase (cyt c ox) in maternal, placental, and fetal tissues at Days 9, 12, and 15 in the 16-day gestation period of the hamster, and following a single dose of either 8 or 15 mg/kg mercuric acetate on the eighth gestational day. Mercury significantly elevated maternal kidney G6PD activity and decreased GP activity. The increase in kidney G6PD strongly correlated with observed urine and kidney abnormalities.