Fermi surface map of large-scale single-orientation graphene on SiO2.

Large scale tetraoctylammonium-assisted electrochemical transfer of graphene grown on single-crystalline Ir(1 1 1) films by chemical vapour deposition is reported. The transferred samples are characterized in air with optical microscopy, Raman spectroscopy and four point transport measurements, providing the sheet resistance and the Hall carrier concentration. In vacuum we apply low energy electron diffraction and photoelectron spectroscopy that indicate transferred large-scale single orientation graphene. Angular resolved photoemission reveals a Fermi surface and a Dirac point energy which are consistent with charge neutral graphene.

Topochemical polymerization of C70 controlled by monomer crystal packing.

Polymeric forms of C60 are now well known, but numerous attempts to obtain C70 in a polymeric state have yielded only dimers. Polymeric C70 has now been synthesized by treatment of hexagonally packed C70 single crystals under moderate hydrostatic pressure (2 gigapascals) at elevated temperature (300 degrees C), which confirms predictions from our modeling of polymeric structures of C70. Single-crystal x-ray diffraction shows that the molecules are bridged into polymeric zigzag chains that extend along the c axis of the parent structure. Solid-state nuclear magnetic resonance and Raman data provide evidence for covalent chemical bonding between the C70 cages.

1,25-Dihydroxyvitamin D3-induced alterations of lipid metabolism in human monocyte-macrophages.

An in vivo atherogenic role of dietary vitamin D has been postulated. To address this hypothesis we sought to determine the in vitro effects of its active circulating metabolite, 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on lipid metabolism in human monocyte-derived macrophages. When cultured 6 days in the presence of 10(-8) M 1,25(OH)2D3 monocyte-macrophages accumulated significantly more triglycerides than control cells: 987.6 +/- 26.8 vs. 779.3 +/- 24.1 micrograms/mg protein (P less than 0.001). Triglyceride accumulation was associated with a hormone-induced stimulation of triglyceride synthesis as determined by [3H]oleate incorporation into cellular triglycerides. The effect of the hormone was significant after 24 h and dose dependent [10(-11) to 10(-8) M 1,25(OH)2D3]. It was specific since 10(-7) M 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 did not stimulate triglyceride synthesis, and its magnitude decreased from 1 to 9 days of culture. 1,25(OH)2D3 (10(-8) M) modified the cholesteryl ester metabolism of monocyte-macrophages only in the presence of acetylated low-density lipoproteins (50 micrograms/ml); it induced a significant increase of cellular cholesteryl ester content (21.9 +/- 1.1 vs. 11.7 +/- 1.7 micrograms/mg protein; P less than 0.001) and of esterification rate of cholesterol measured by [3H]oleate incorporation into cellular cholesteryl esters (17.2 +/- 0.9 vs. 6.5 +/- 0.3 nmol.mg protein-1.24 h-1; P less than 0.001) by comparison with control cells. These results show that 1,25(OH)2D3 alters in vitro lipid metabolism in the human monocyte-macrophage and suggest a new in vivo role for the hormone.

Prophylaxis of amygdala kindling-induced epileptogenesis: comparison of a GABA uptake inhibitor and diazepam.

The prophylactic effect of an inhibitor of synaptosomal GABA uptake, SK&F 89976-A (N-[4,4-diphenyl-3-butenyl]-nipecotic acid), on the development of amygdala kindled seizures was studied in adult female rats. For comparative purposes, the action of diazepam was also investigated. Dosages of SK&F 89976-A and diazepam which were previously shown to be the ED50 for seizure inhibition in fully kindled rats (15 mg/kg and 2 mg/kg i.p., respectively) were administered daily 30 min prior to amygdala stimulation in naive, unkindled rats. Both drugs inhibited the evolution of full kindled seizure activity and markedly suppressed kindling-associated increases in the duration of behavioral and electrographic seizures. Control rats developed fully kindled stage 5 seizures after 8.9 +/- 1.1 amygdala stimulations but drug-treated rats did not progress beyond an early stage of kindled seizures as long as the animals were treated with the drugs (22 days). Diazepam produced significant CNS depressant effects throughout the course of administration but SK&F 89976-A prevented kindling with no depressant side effects. The ability of SK&F 89976-A and diazepam to inhibit the development of full amygdala kindled seizures may be related to enhancement of central inhibitory GABAergic systems.

Prevention of amygdala kindling with an inhibitor of gamma-aminobutyric acid uptake.

A novel, specific inhibitor of gamma-aminobutyric acid (GABA) uptake, SKF 89976-A (N-[4,4-diphenyl-3-butenyl]-nipecotic acid), was administered daily (15 mg/kg, i.p.) 30 min prior to amygdala stimulation in adult female rats. Whereas control rats developed full kindled seizures after 9.4 +/- 1.2 amygdala stimulations. SKF 89976-A-treated rats had not progressed beyond an early stage of kindled seizures by the termination of drug treatment after 22 episodes of daily amygdala stimulation. Following cessation of SKF 89976-A treatment, full kindled seizures developed after 4.1 +/- 0.9 additional amygdala stimuli. The data suggest that SKF 89976-A can inhibit generalization of amygdala-kindled seizures, possibly by enhancement of central GABAergic activity.

Age-related alterations in trimethoprim-sulfadiazine disposition following oral or parenteral administration in calves.

Age-related changes in the absorption and distribution patterns of trimethoprim/sulfadiazine were studied following oral or subcutaneous administration of 15 mg/kg of the drug combination in calves. Following oral administration, the time course of trimethoprim/sulfadiazine appearance and dissipation in serum, synovial fluid and urine was followed for periods up to 48 hours in calves one day, one week and six weeks of age. The profiles of drug appearance-disappearance in these body fluids were also determined after subcutaneous administration in seven week old calves. The peak serum and synovial fluid levels of trimethoprim/sulfadiazine achieved following oral administration were substantially lower with increasing maturation. In ruminating (six and seven week old) calves, subcutaneous or oral administration of the combination led to high serum levels of sulfadiazine but little or no serum trimethoprim was detected in animals at this age. The data indicate that, while therapeutic concentrations and optimum ratios of the drugs may be achieved for extended time periods in neonatal life, this dosage is unable to produce optimum serum and synovial fluid concentrations as the calves mature.

Teratogenic effect of calcium edetate (CaEDTA) in rats and the protective effect of zinc.

The calcium chelate of EDTA (CaEDTA) currently is the drug of choice in the treatment of lead intoxication. This study investigated the teratogenic potential of CaEDTA, administered parenterally during periods of organogenesis and determined if incorporating zinc into EDTA would protect against teratogenic effects. Four doses (2, 4, 6, and 8 mmol/m2/day) of CaEDTA, two concentrations (8 and 20 mmol/m2/day) of ZnEDTA and ZnCaEDTA (molar ratio 0.5:0.5:1) were used, and a saline control (0.9% NaCl). Timed-pregnant Long-Evans rats were assigned at random to the treatment groups, 20 per dose for each chelate and 30 to the saline control. Rats were injected with the chelate or saline solution sc, twice daily during the 11th through 15th days of gestation. Pups removed by cesarean section on the 21st day were processed for osseous and visceral examination. Additional animals per treatment group were used for maternal plasma and liver and fetal zinc determinations. Results showed increases in several abnormalities (submucous cleft, cleft palate, adactyly-syndactyly, curly tail, abnormal rib and vertebrae) with increasing amounts of CaEDTA. No malformations were seen with ZnEDTA at either dose or with ZnCaEDTA at 8 mmol/m2/day. However, submucous cleft was seen in 6 of 20 litters from the dams receiving the higher dose of ZnCaEDTA. It was concluded that CaEDTA is teratogenic in rats at concentrations which, except for decreased weight gain, produce no discernible toxicity to the dam, and which are comparable to the recommended therapeutic dosage in humans (1500 mg/m2/day corresponding to 4 mmol/m2/day). Protection is afforded by incorporating zinc in the chelate.

Lifetime lead intoxication: influence on the amygdaloid kindling model of epileptogenesis.

The nature of amygdaloid kindled seizures was studied in adult rats which were intoxicated with lead starting in neonatal life. Lactating females were exposed to lead via the drinking water (0.25% lead acetate) and the litters were continued on this level of lead after weaning at 27 days of age. When compared to controls, levels of lead in the blood and brain were significantly higher in lead-exposed rats, both at the time of weaning as well as postkindling, beyond 150 days of age. Parameters relating to amygdaloid kindled seizures, including the rate of kindling, seizure latency and seizure threshold were not significantly different in lead-treated rats than in controls. However, duration of behavioral seizures and afterdischarges was significantly longer in rats exposed to lead. Our data suggest that, although lead intoxication starting in neonatal life does not appear to affect the susceptibility to development of amygdaloid kindled seizures, it may enhance seizure severity in this model of epileptogenesis.

Lead intoxication and the amygdaloid kindling model of epileptogenesis in the adult rat.

The influence of lead intoxication on the seizure state produced by amygdaloid kindling was studied in rats. Exposure to 1% lead (in the form of lead acetate) in drinking water for periods up to 4 weeks led to significant increases in lead content in the blood and various brain regions. Signs of lead intoxication, including behavioral depression, loss of body weight and decreased hematocrit were produced by this treatment regime. The intensity and nature of behavioral convulsions as well as the rate of development of amygdaloid kindled seizures did not appear to be affected by lead intoxication. However, lead exposure during kindling led to significant increases in an electrographic aspect of the seizure, i.e., the afterdischarge duration. Although pair-fed controls were not utilized and therefore definitive conclusions cannot be made, our data would seem to indicate that lead intoxication has a relatively minor ability to potentiate amygdaloid kindling in adult rats.

Vitamin B12 binding proteins in bovine serum.

Examination of bovine serum by the diethylaminoethyl cellulose small column method revealed three proteins binding vitamin B12. The elution pattern suggested that they are similar to the three transcobalamins recognized in human serum. Distribution of unbound binding capacity among serum binders was assessed in serum from normal, ketotic, and B12- and Factor B-supplemented cows in early lactation. No major differences were observed among groups; however, cow serum displayed a pattern different from human serum. Mean total binding capacity of bovine serum for B12 as well as mean unbound binding capacity were lower than the corresponding means for human serum.