High-resolution (1)H NMR spectroscopy in organs and tissues using slow magic angle spinning.

It is shown that high-resolution (1)H NMR spectra of intact excised tissues and organs can be obtained by rotating the sample slowly about an axis at the magic angle of 54 degrees 44' with the external magnetic field. In this way tissue and cellular damage invoked by standard magic angle spinning (MAS) experiments, where spinning speeds of several kHz are typically employed, are minimized. Special RF pulse sequences, developed originally in solid state NMR, can be used to produce a spinning sideband-free isotropic spectrum. In this article the first results are shown of the brain, heart, liver, gluteus muscle, and kidney excised from mice using the 2D-phase-altered spinning sidebands (PASS) technique and employing MAS spinning speeds of 43-125 Hz. It was found that with slow sample spinning similar, and in some cases even better, spectral resolutions are obtained as compared with fast MAS.

An investigation of rat mammary healthy and R3230AC tumor tissues and cells by means of solid-state 13C NMR.

The first results are shown of a low temperature 13C solid-state, cross-polarization magic angle spinning (CPMAS) NMR study of R3230AC rat mammary carcinoma transplanted into female Fischer rats. Intact, healthy mammary tissues and tumor tissues, quickly frozen at -78 degrees C after excision, were examined, as were normal epithelial cells and tumor cells extracted from these tissues. The experiments were performed at -100 degrees C and -40 degrees C. The solid-state 13C NMR spectrum of the healthy tissue is dominated by the triacylglycerols present in the adipose tissue. The solid-state spectra of the other compounds differ significantly from the spectrum of the healthy tissue, and are dominated by the phospholipids and the large molecular weight proteins, for a major part present in the membranes. The spectra of the tumor tissues and the tumor cells were very similar, in accordance with the fact that the tumor tissues consisted of 80-90% tumor cells. The spectrum of the normal cells shows the same general features as those of the tumor tissue and tumor cells, but also exhibits some significant differences. The main difference at -100 degrees C is that, in the tumor samples, the relative intensity of the resonance line arising at 30 ppm, which is due to methylene chains, is reduced. At -40 degrees C this intensity is further reduced in the tumor samples, whereas the spectrum of the normal cells remains unaltered. It is tentatively concluded that the spectral differences between the normal and the malignant cells are due to changes in mobilities occurring in the cells after tumorigenesis, and that compared with normal epithelial cells the tumor cells contain an increased amount of mobile methylene chains. These differences virtually disappear if the samples are preserved at temperatures equal to or above 4 degrees C, emphasizing the importance of sample preservation at low temperatures, and hence of the solid-state NMR approach to investigate structures and dynamics in cells before and after tumor formation.

Reproduction, growth, and development of rats during chronic exposure to multiple field strengths of 60-Hz electric fields.

A study with multiple exposure groups and large group sizes was performed to establish whether exposure to 60-Hz electric fields would result in reproductive and developmental toxicity. A response model was developed from previous results and tested in groups of rats exposed to electric fields at various field strengths. Female rats were mated, and sperm-positive animals randomly distributed among four groups: sham-exposed or exposed to 10, 65, or 130 kV/m, 60-Hz vertical electric fields. Animals were exposed for 19 hr/day throughout the experiment. During gestation, exposure to the higher field strengths resulted in slightly depressed weight gains of dams. Offspring were born in the field and remained with their dams through the suckling period. Numbers of pups per litter and pup mortality did not differ among the exposure groups. Dams exposed at 65 kV/m lost slightly more weight through the lactation period than the control group. Male pups exposed to higher field strengths gained slightly less weight from 4 to 21 days of age than did sham-exposed animals. At weaning, two F1 females per litter (randomly selected) continued on the same exposure regimen were mated at 11 weeks of age to unexposed males, and euthanized at 20 days of gestation. Uterine contents were evaluated, and all live fetuses were weighed and examined for external, visceral, and skeletal malformations. Fertility and gestational weight gain of F1 females were not affected by exposure, nor was prenatal viability or fetal body weight. No significant increase in the incidence of litters with malformations was observed. Although no developmental toxicity was detected, exposures produced physical changes in the dams, evidenced as a rust-colored deposit on the muzzle and ears (chromodacryorrhea) that increased in incidence and severity at 65 and 130 kV/m. Incidence of chromodacryorrhea was not significantly different between sham-exposed rats and those exposed at 10 kV/m.

Brown-colored deposits on hair of female rats chronically exposed to 60-Hz electric fields.

An increased incidence and severity of a brownish coloration of hair has been observed around the nose and on the ears of female rats that were chronically exposed to 60-Hz electric fields. Microscopic examination of the colored areas revealed a red-brown globular deposit on hair shafts in affected areas without signs of physical injury.

Rats reproduce and rear litters during chronic exposure to 150-kV/m, 60-Hz electric fields.

Mature female rats and their subsequent litters were exposed either to 112- or to 150-kV/m, 60-Hz electric fields or sham-exposed for 19 h daily through pre-breeding, breeding, and rearing periods of experimentation. Exposed females mated in equal percentages and reared litters of equal numbers, and mean body masses of pups were the same as those of sham-exposed animals. Thus, experiments to investigate electric-field effects on reproduction and development in rats are feasible at effective field strengths of 112 and 150 kV/m.

Developmental studies of Hanford miniature swine exposed to 60-Hz electric fields.

Evaluations of reproductive and developmental toxicology, including teratology, were included as part of a broad screening study in Hanford Miniature swine (HMS) to detect effects of exposure to electric fields. One group (E) was exposed to a uniform, vertical, 60-Hz, 30-kV/m electric field for 20 h/day, 7 days/week; sham-exposed (SE) swine were housed in a separate, environmentally equivalent building. The first generation (F0) gilts were bred after 4 months of study; some were killed for teratologic assays at 100 days of gestation (dg), and the others produced an F1 generation of offspring. The pooled incidence of terata in these litters (teratologic assays and live births) was similar in the E and SE groups. The F0 females, which produced the F1 generation, were bred again after 18 months of exposure and were killed at 100 dg. Malformation incidence in E litters (75%) was significantly greater than in SE litters (29%). No consistent differences in litter size, fetal mass, or mass of fetal organs were detected. The F1 gilts were bred at 18 months of age; defective offspring were found in significantly more of the E litters (71%) than in SE litters (33%). These F1 females were bred again 10 months later and teratologic assays were performed on their second litters at 100 dg. The percentage of litters with malformed fetuses was essentially identical in the E and SE groups (70% and 73%, respectively). There appears to be an association between chronic exposure to a strong electric field and developmental effects in swine, although the change in incidence of malformations between generations and between the first and second breedings makes it impossible to conclude unequivocally that there is a cause-and-effect relation.

Reproduction and development in rats chronologically exposed to 60-Hz electric fields.

Previous studies have raised the possibility of reproductive and developmental changes in miniature swine chronically exposed to a strong 60-Hz electric field. Two replicate experiments on rats were performed to determine if similar changes could be detected in animals exposed under a comparable regime, which was based on average, induced-current densities and on the chronology of reproductive development, as dosimetrically and biologically scaled. Beginning at three months of age, female rats of the F0 generation and their subsequent offspring were chronically exposed to a 60-Hz electric field (100 kV/m unperturbed) for 19 h/day for the duration of experimentation. After four weeks of exposure, F0 female rats were mated to unexposed male rats during the field-off period. No significant developmental effects were detected in their litters, confirming our previous results with swine and rats. The F0 females were mated for a second time at 7.2 months of age, and the fetuses were evaluated shortly before term. In the first experiments, the incidence of intrauterine mortality was significantly less in exposed than in sham-exposed litters, and there was a tendency (P = .12) for an increased incidence of malformed fetuses in exposed litters. Neither end point was significantly affected in the second experiment. Copulatory behavior of the female F1 offspring, which were bred at three months of age, was not affected in either experiment. There was a statistically significant decrease in the fertility of F1 exposed females and a significant increase in the fraction of exposed litters with malformed fetuses in the first experiment; both end points were essentially the same in the sham and exposed groups of the second experiment. That the significant effects detected in the first experiment were not seen in the second may be attributed to random or biological variation. Alternatively, the finding may indicate that the response threshold for induction of malformations lies near 100 kV/m.

Developmental toxicity following oral administration of a high-boiling coal liquid to pregnant rats.

Heavy distillate (HD), the highest-boiling coal liquid from the solvent-refined coal-II process (SRC-II), was administered by intragastric (IG) intubation to pregnant rats. Five dose levels of HD (0.09, 0.14, 0.18, 0.36 and 0.74 g kg-1), were given daily from 12 to 16 days of gestation and the rats were killed at 20 days of gestation. Maternal body weights and weights of the liver, kidneys, spleen, adrenals, thymus, ovaries and the gravid uterus were obtained. Gravid uteri were evaluated for prenatal mortality. Live fetuses were examined for malformations and weighed; fetal lungs were excised and weighed. Maternal (extragestational) weight gains and thymic weights diminished in all groups that received the SRC material. Adrenal weights were increased in all treated animals, except for those in the lowest-dose group (0.9 g kg-1). There was significant maternal mortality at 0.74 g kg-1 and increased intrauterine mortality at doses of 0.37 and 0.74 g kg-1. Placental weight was depressed, and the incidence of fetal anomalies was increased at 0.14 g kg-1 and all higher dose levels.

Effect of day gestation on inductions of lambing with flumethasone.

Three-hundred and sixty-nine ewes were examined for the effect of day of flumethasone injection on induction of parturition. Ewes were treated with either 2 mg flumethasone (FLU) or physiological saline (control) on days 138 through 144 of gestation as determined by date of marking by rams. Average time to lambing post-treatment was 86.7 +/- 8.0 hr for FLU-injected ewes and 155.9 +/- 7.9 hr for control ewes (P less than 0.1). Sixty-four percent of the FLU-injected ewes lambed within 72 hr after treatment, compared to 17% of the control ewes (P less than .01). The average interval to lambing for the FLU-treated ewes responding within 72 hr was 49.5 +/- 2.1 hours. FLU treatment on days 140 through 144 of gestation resulted in a shorter (P less than .05) interval from treatment to birth and more (P less than .01) ewes lambing within 72 hr after treatment than did treatment on days 138 and 139.