Ictal and interictal brain SPECT imaging in epilepsy using technetium-99m-ECD.

UNLABELLED: The aim of this study was to evaluate the use of 99mTc-ethyl cysteinate dimer (ECD), also known as 99mTc-bicisate, in the presurgical evaluation of patients suffering from medically intractable epilepsy. METHODS: Twenty-three brain SPECT studies (8 ictally and 15 interictally) were performed on 16 patients with a high-resolution annular SPECT system (CERASPECT). For the ictal studies, the tracer was injected in the very early phase of the seizure. The delay between seizure onset and 99mTc-ECD injection was 2-20 sec. RESULTS: Interictally, all patients showed circumscribed hypoperfusions. In four patients, the SPECT lesion represented only structural defects. Circumscribed increased tracer uptake was observed in all ictal studies. For all patients with temporal lobe epilepsy without significant mass lesion, in whom an interictal and ictal 99mTc-ECD-SPECT study could be obtained, the asymmetry index was 0.88 +/- 0.03 for the interictal and 1.23 +/- 0.08 for the ictal studies. CONCLUSION: The data suggest that 99mTc-ECD is an effective marker of cerebral perfusion imaging in epilepsy. In comparison to other tracers, it has a high in vitro stability and is therefore particularly useful for ictal studies in the very early phase after seizure onset.

Teratogenesis of calcium valproate in rabbits.

The calcium salt of valproic acid (Valontin) has been proposed for use in the treatment of absence, myoclonic, and tonic clonic seizures of the primarily generalized type. The present study was conducted to determine the teratogenic potential of calcium valproate in rabbits. Groups of 20 Dutch-belted rabbits were given oral doses of 50, 150, or 350 mg/kg on days 6-18 of gestation. A reference group was given 350 mg/kg sodium valproate and control groups were untreated or given vehicle alone. Animals were observed daily and body weights were recorded on gestation days 0, 6, 13, 18, and 30. Litter and fetal parameters were evaluated following uterotomies on day 30. No drug-related clinical signs or deaths occurred. Postimplantation loss and the incidence of malformed vertebrae and ribs, rudimentary or absent pollices, and extra vertebrae and ribs were increased at 350 mg/kg with both calcium and sodium salts of valproic acid. At the 150-mg/kg dose level, calcium valproate markedly increased the incidence of supernumerary ribs. No teratogenic or embryotoxic effects were seen with calcium valproate at 50 mg/kg. These data indicate that the sodium and calcium salts of valproic acid exhibit teratogenic potential in rabbits.

Teratology study in rats with amsacrine, an antineoplastic agent.

Amsacrine, an acridinylamino derivative used in the treatment of refractory leukemias, was evaluated for its teratogenic potential in pregnant rats. The compound was given by intraperitoneal (ip) administration on Days 6 to 9 of gestation to groups of 20 female CD rats at levels of 0.5, 1.0, and 2.0 mg/kg. Appropriate vehicle and untreated controls were included. Dams given 2.0 mg/kg lost weight during and after the treatment period. Food consumption was comparable to controls at all dose levels except for the high dose group in the post-treatment period. Decreased litter size, increased postimplantation loss, and reduced fetal weights occurred with doses of 2.0 mg/kg. Significantly reduced fetal body weight and increased incidence of stunting were the only adverse findings at 0.5 and 1.0 mg/kg, respectively. Two fetuses at 2.0 mg/kg, one at 1.0 mg/kg, one at 0.5 mg/kg, and two vehicle control fetuses had gross abnormalities. Fetotoxicity, manifested by inhibition of osteogenesis and minor skeletal abnormalities, occurred with doses of 0.5 mg/kg or more. The results indicate that amsacrine was embryolethal to rats at doses of 2.0 mg/kg and embryotoxic at lower dose levels. Teratogenicity was not evident at doses which did not affect fetal survival.

Teratology study with the synthetic prostaglandin ONO-802 given intravaginally to rabbits.

ONO-802, a synthetic E1 prostaglandin, was administered intravaginally via pessaries to Dutch belted rabbits at doses of 250, 62.5, and 12.5 micrograms/kg on days 6 through 18 of gestation. Rabbits in a vehicle control group were treated with pessaries that did not contain ONO-802 during the same period. Another group of animals remained untreated throughout gestation. Necropsies were performed on rabbits found dead and on those killed on gestation day 30. Body weight, food and water consumption, and clinical signs were monitored during the experiment. Major organs were weighed when the dams were necropsied on gestation day 30, and litter and fetal data were collected. Abortion and maternal deaths occurred in drug-treated groups. Body weight gains and food and water consumption were adversely affected by treatment particularly at the 250 and 12.5 micrograms/kg dose levels. Wastage (postimplantation loss) was significantly increased among treated groups (all dose levels), while other litter and fetal parameters were unaffected. ONO-802 was not teratogenic at maternal and embryotoxic dose levels.

Two-phase teratology study with the synthetic prostaglandin ONO-802 given intravaginally to rats.

The synthetic prostaglandin ONO-802 was administered intravaginally to Sprague Dawley rats at doses of 1.0, 0.5, and 0.125 mg/kg on days 6 through 15 of gestation. A vehicle control group was treated with pessaries that did not contain the drug while another group remained untreated. Body weight, food, water consumption, and clinical signs were monitored during the experiment. In Phase One, 20 pregnant animals from each group were sacrificed at term, major organs were weighted, and litter and fetal data were collected. In Phase Two ten dams per group were allowed to deliver their litters, and the offspring were evaluated for survival, growth, developmental signs, and physiological function. Selected F1 offspring were retained to assess learning and emotional behavior or reproductive capacity. Administration of either 0.5 or 1.0 mg/kg of ONO-802 resulted in a slight reduction in food consumption and body weight gain. Water consumption was increased both during and after the dosing period for the mid and high dose dams. Significantly increased weights for the heart, lungs, liver, adrenals, and ovaries and decreased weights for the thymus gland were noted at term sacrifice of the 1.0 mg/kg dams, whereas the 0.5 mg/kg group had increased weights of the adrenals and ovaries only. Litter parameters were unaffected by treatment. Weights of the female fetuses of the 1.0 and 0.5 mg/kg groups were significantly reduced when compared to controls. There were no significant drug-related abnormalities among the F1 offspring and no evidence that treatment of the F0 dams affected the development, behavior, or reproductive performance of the F1 offspring. Thus, ONO-802 was not teratogenic when given to rats by the intravaginal route.

Teratogenesis of calcium valproate in rats.

Studies were conducted to determine the teratogenic potential of the calcium salt of valproic acid in rats when given orally at doses of 600, 150, and 50 mg/kg on days 6--15 of gestation. The sodium salt of valproic acid was used as a reference agent at a dose level of 600 mg/kg. The administration of 600 mg/kg/day of either calcium or sodium valproate resulted in transient, severe sedation in the dams. Four dams receiving 600 mg/kg of either salt died during the experiment, with deaths occurring between day 7 and 11 of gestation. Food consumption and body weight gain were significantly reduced during the dosing period with both salts at dose levels of 600 mg/kg. Embryotoxicity at the high doses (600 mg/kg) with either salt was manifested by increases in fetal resorption, reduced body weights, and significantly increased incidence of supernumerary ribs and bifid vertebral centra among the surviving fetuses. A teratogenic effect was evident at 600 mg/kg with either salt of valproic acid. Seven of 16 fetuses from dams given the calcium salt were abnormal. Findings included one with omphalocele and six others with skeletal malformations. Eleven of 24 fetuses from dams given the sodium salt were abnormal: three littermates had bilateral ectrodactyly of the rear feet and malformed vertebral centra and eight others had skeletal malformations. No teratogenic effect was evident among the fetuses from dams given 150 mg/kg calcium salt. Embryotoxicity was demonstrated by a significant increase in the incidence of supernumerary ribs. No adverse effect was observed among the fetuses from dams given 50 mg/kg of the calcium salt.

Competitive progesterone antagonists: receptor binding and biologic activity of testosterone and 19-nortestosterone derivatives.

Testosterone and 19-nortestosterone derivatives were evaluated in a developmental scheme designed to identify competitive progesterone antagonists having abortifacient activity. Compounds that displayed significant binding to the rabbit uterine progesterone receptor were followed in biologic tests for progestational, antiprogestational, and abortifacient activities. Of the seven compounds tested for both progestational and antiprogestational activity, only one, 5 alpha-dihydronorethindrone, behaved exclusively as an antagonist. Five other 19-nortestosterones (19-nortestosterone, 17 beta-hydroxyestra-4, 9(10)-dien-3-one, norethindrone, norethindrone acetate, and R 2323) proved to be mixed agonists/antagonists. 5 alpha-Dihydronorethindrone, norethindrone, and 19-nortestosterone terminated pregnancy during the postnidatory period in rats; in addition, the latter two compounds inhibited progesterone-supported pregnancy in spayed rats and curtailed pregnancy during the postnidatory period in hamsters. These results demonstrate that several 19-nortestosterone derivatives bind to the uterine progesterone receptor and behave either as antagonists or mixed agonists/antagonists.

Cyclic and temporal differences in LH-RH-stimulated LH release in cultured rat pituitary cells.

To establish whether the enhanced LH-RH responsiveness shown by pituitary gonadotrophs at proestrus in vivo could be maintained in vitro, rat anterior pituitary cells were investigated to determine differences in LH release in response to LH-RH through the estrous cycle and with time in primary culture. Pooled or individual anterior pituitary glands from each day of the cycle were dissociated with collagenase, hyaluronidase and Viokase and cultured for from 1 to 4 days. Four-day cultures of proestrous cells did not show differences in LH-RH responsiveness when compared to estrous, diestrous I and diestrous II cells. In addition, proestrous cells did not show differences in LH-RH responsiveness when compared to diestrous II cells after 1, 2, 3 or 4 days of culture; however, over the same 1--4 days of culture, proestrous cells contained higher amounts of LH and released greater quantities of LH into the growth medium than did diestrous II cells. It was also observed that both proestrous and diestrous II cells exhibited significantly greater LH-RH responsiveness after 3 or 4 days of culture than after 1--2 days of culture. These results suggest that the differential LH-RH responsiveness shown by pituitary gonadotrophs at proestrus in vivo is not maintained when pituitary cells are placed in primary culture.

Potency of synthetic luteinizing hormone releasing hormone preparations in rat anterior pituitary cell cultures.

Selected synthetic luteinizing hormone releasing hormone preparations were assayed, and their potencies were determined relative to one sample utilizing primary cultures of enzymatically dispersed rat anterior pituitary cells. Preliminary cell culture experiments indicated that luteinizing hormone releasing hormone had to be in constant contact with cells for continued luteinizing hormone secretion. Luteinizing hormone levels in media reached a maximum concentration after 4 hr of continuous luteinizing hormone releasing hormone exposure. Cell culture bioassay was selected over the bioassay employing chronically ovariectomized steroid-blocked rats due to greater sensitivity and economy. The assay of each luteinizing hormone releasing hormone preparation was replicated four to seven times. Preparations from several companies were less potent (p less than 0.05) than the reference product. Contaminants were disclosed by TLC in preparations with potencies lower than the reference product.