Characteristics of steel slag under different cooling conditions.

Four types of steel slags, a ladle slag, a BOF (basic oxygen furnace) slag and two different EAF (electric arc furnace) slags, were characterized and modified by semi-rapid cooling in crucibles and rapid cooling by water granulation. The aim of this work was to investigate the effect of different cooling conditions on the properties of glassy slags with respect to their leaching and volume stability. Optical microscopy, X-ray diffraction, scanning electron microscope and a standard test leaching (prEN 12457-2/3) have been used for the investigation. The results show that the disintegrated ladle slag was made volume stable by water granulation, which consisted of 98% glass. However EAF slag 1, EAF slag 2 and the BOF slag formed 17%, 1% and 1% glass, respectively. The leaching test showed that the glass-containing matrix did not prevent leaching of minor elements from the modified slags. The solubility of chromium, molybdenum and vanadium varied in the different modifications, probably due to their presence in different minerals and their different distributions.

Seizure susceptibility in DBA and C57 mice: the effects of various convulsants.

Convulsive dose 50s (CD50s) for various convulsive drugs and minimal and maximal electroshock seizure thresholds were determined in DBA and C57 mice. DBA mice had lower maximal electroshock seizure thresholds (MESTs, 15%) and CD50s for homocysteine thiolactone (HTL, 23%) and bicuculline (69%), and a higher CD50 for pentylenetetrazol (PTZ) at 3 weeks of age, the age of maximal audiogenic seizure (AGS) susceptibility. At 8 weeks, when DBA mice are not susceptible to AGSs, significant differences were a lower minimal electroshock seizure threshold (mEST, 37%) and maximal EST (MEST) (19%), lower CD50s for N-methyl-D-aspartate (NMDA) (39%), kainic acid (KA, 50%), HTL (32%), strychnine (37%), and a higher CD50 for nicotine (55%) in DBA mice. Based on these data it is suggested that pathways involving NMDA and KA receptors are responsible for increased susceptibility to seizure initiation (mEST), and are opposed by glycine pathways, and that opposing GABA and cholinergic systems at higher CNS levels are involved in seizure spread (AGSs and MEST) in these mice. Latency patterns indicate that nicotine, strychnine, PTZ and bicuculline have high blood-brain barrier (BBB) penetrability. Picrotoxin and the excitatory amino acid receptor agonists had longer latencies, suggesting low BBB penetrability. Age-related changes in latency, however, give evidence that difficulty in drug penetration of the BBB is not responsible for differences observed in CD50s between strains.

Extracellular (36Cl) space, electrolyte, protein, and DNA content in brain of DBA and C57 mice: effects of age.

DBA/2J (DBA) mice are susceptible to audiogenic seizures (AGSs) in an age-dependent manner, susceptibility being maximal at 21 days and absent at 110 days of age. Previous studies have demonstrated that there is a decrease in anion transport and an increase in carbonic anhydrase (CA) activity in brain from DBA mice as compared with C57BL/6J (C57, non-AGS) mice at 21 days. Since these results suggest that there are alterations in cellular and electrolyte composition of brain from DBA mice, the present work was directed toward determining electrolyte content, extracellular space, and DNA content of brain from DBA and C57 mice at 21 and 110 days of age. There was a decrease in intracellular chloride and sodium content, and an increase in intracellular potassium content in cerebral cortex, cerebellum, and brainstem from DBA mice at both 21 and 110 days. Also, extracellular space was larger in these three brain tissues from DBA mice at both ages. DNA content, not different between the strains at 21 days, was significantly lower in cerebellum from DBA mice at 110 days. These findings give further evidence of alterations in the transport of ions in brain from DBA mice. In addition, they demonstrate that there are alterations in the intracellular and extracellular space values, an indication of changes in cellular composition of brain in these mice. Such changes may contribute to AGS susceptibility by disrupting the balance that normally exists in the neuronal microenvironment of the central nervous system.

Acute and chronic acetazolamide administration in DBA and C57 mice: effects of age.

The clinical utility of the carbonic anhydrase (CA) inhibitor acetazolamide (ACTZ) is limited because of rapid development of tolerance to its effects. Tolerance is thought to develop as a result of glial cell proliferation and/or increased CA synthesis. DBA mice, susceptible to audiogenic seizures (AGSs) in an age-dependent manner, have increased CA activity as compared with C57 (non-audiogenic seizure susceptible) mice at 21 and 110 days of age. The present work utilized ACTZ to help determine the relationship between increased CA activity in brain and AGSs in DBA mice. Also, minimal electroshock seizure threshold (EST) was measured at various ages in DBA and C57 mice to determine age-related changes in CNS excitability. EST was significantly lower in DBA as compared with C57 mice at 18 days and between 40 and 115 days of age, suggesting that DBA mice remain hyperexcitable to electrical stimulation after they develop resistance to AGSs. ACTZ ED50s against maximal electroshock seizures (MES) were significantly higher in DBA as compared with C57 mice at 26,36, and 115 days of age. This finding correlates with higher CA activity in this strain at 110 days of age, noted previously. However, at 21 days of age, when CA activity is also higher in DBA versus C57 mice, there were no significant differences in ACTZ ED50s against MES between the strains. ACTZ ED50s against AGSs in DBA mice were considerably lower than ACTZ ED50s against MES in either strain, suggesting that a particular fraction of CA is intimately involved in the production of AGSs.(ABSTRACT TRUNCATED AT 250 WORDS)

Subcellular distribution of carbonic anhydrase and Na+, K+- and HCO3--ATPases in brains of DBA and C57 mice.

DBA/2J mice are susceptible to audiogenic seizures (ASs) in an age-dependent manner, susceptibility being maximal at 21 days of age and declining thereafter. DBA, as compared with AS-resistant C57BL/6J (C57) mice, had higher carbonic anhydrase (CA) activity in cerebral cortex, brainstem, and cerebellum homogenates at 21 days of age. CA activity was also increased in cytosolic (82%), microsomal (167%), and myelin (68%) subcellular fractions from cerebral cortex, and in cytosolic (51%) and mitochondrial (102%) fractions from brainstem of DBA mice at 21 days of age. In addition, DBA mice had a higher Na+, K+-ATPase activity in myelin from cerebral cortex, and a lower HCO3--ATPase activity in mitochondria from brainstem. The differences in CA activity in the cerebral cortex and in HCO3--ATPase were not present at 110 days of age, when DBA mice are no longer susceptible to ASs. Because CA and HCO3--ATPase are involved in maintaining a proper ionic environment for neuronal function, these data suggest that alterations in activity of these enzymes are related to the age-dependent changes in AS susceptibility in DBA mice.

Radioiodide uptake in brain, CSF, thyroid, and salivary glands of audiogenic seizure mice.

DBA/2J (DBA) mice are susceptible to audiogenic seizures (ASs) in an age-dependent manner. Anion transport as measured by radioiodide uptake was determined in thyroid gland, salivary gland, skeletal muscle, cerebral cortex, cerebellum, brainstem, and CSF from these mice at various ages. Anion transport was also determined in C57BL/6J(C57) mice, an AS-resistant strain. In thyroid, DBA mice had an enhanced ability to concentrate iodide at 21 days of age when they have maximal AS susceptibility, as compared with the same-aged C57 mice. This difference in thyroid function was less marked at 40 days of age, when DBA mice are less AS susceptible, and was absent at 110 days of age, when DBA mice are AS resistant. In brain, differences in iodide uptake were also noted between these two strains of mice at 21 days of age. DBA mice had an increased concentration of iodide in CSF, an indication that they have a defect in the transport of iodide out of the CSF across the choroid plexus. In addition, DBA mice had a lower ratio of cerebral cortex to CSF iodide, which suggests that DBA mice have a defect in the transport of this anion into cerebral cortical cells from brain interstitial fluid. These differences in iodide transport in brain decreased with age as the AS susceptibility of DBA mice decreased. These results suggest a relation between anion transport in thyroid gland, cerebral cortex, and choroid plexus and AS susceptibility in DBA mice at 21 days of age.

Ionic and acid-base regulation of neurons and glia during seizures.

Much evidence shows that glia regulates the cation and anion content of brain interstitial space. In rats the pH and bicarbonate (HCO3-) concentration of neurons and glia were derived from carbon 14-labeled HCO3- and dimethyloxazolidinedione uptake into brain and cerebrospinal fluid. Acetazolamide increases the total CO2 concentration in neurons and decreases the pH and HCO3- concentration in glia. Inhibition of glial carbonic anhydrase (CA) reduces conversion of neuronally derived CO2 to HCO3-, glial pH is lowered, and neuronal CO2 accumulates. CA therefore has an essential role in regulating pH in neurons, glia, and interstitial fluid. In audiogenic seizure mice, glial CA activity is increased and glial anion transport is reduced. As the mice age, seizure susceptibility, the increased CA activity, and the defect in anion transport disappear concurrently. The enhanced CA activity in the glial cells of these mice is an adaptive mechanism to overcome the defect in anion transport that results from a deficiency of HCO3- -dependent and Na+- and K+ -dependent adenosine triphosphatase. Pentylenetetrazol stimulates neurons in neonatal rats, but after 10 days of age, when glia is present, it too is stimulated and the seizures are attenuated. Cobalt implantation in the cortex of rats also induces a glial response that ameliorates the focal seizures produced by this procedure.

Differences between arm span and stature in white children.

Arm span and stature were measured at 6-month intervals in 160 normal children from 8 to 15 years of age. The mean difference between arm span and stature is greater in boys than in girls at all ages. In boys, the mean arm span is always greater than mean stature. The difference in girls in always less than 1 cm, but the sign changes from negative to positive at 11.5 years. An arm span-stature difference outside the 90% confidence limits suggests the possibility of a clinical condition that differentially affects the elongation of the trunk and of the limbs.