Ganglioside changes associated with temporal lobe epilepsy in the human hippocampus

To understand better the molecular and cellular events associated with status epilepticus, a multifaceted analysis has begun on hippocampal tissues therapeutically removed from patients with temporal lobe epilepsy. In this first study, quantitative changes in major ganglioside species are reported, as well as the immunocytochemical localization on the ganglioside GD3 in epileptic human hippocampus. Although significant variations were found between patients, the pattern of change was consistent when compared to normal values obtained from an autopsied specimen and the literature. Total ganglioside content was reduced in epileptic hippocampi, which was attributable, in part, to pyramidal cell loss found in CA1 and CA3. In each case, the percentage of ganglioside GD3 was increased significantly, while ganglioside GD1a decreased. The former change is probably associated with reactive astrocytosis and the latter with loss of neuronal dendrites. Immunocytochemical localization revealed GD3 in the stratum radiatum and the subgranular layer of the dentate gyrus. In these areas, GD3 was present in punctate structures and astrocytes. These findings indicate that GD3 increases in selected areas of the sclerotic hippocampus and is presumably related to localized accumulation of reactive glial cells. Since gangliosides have a high affinity for calcium and localized increase in extracellular calcium could disrupt normal neuronal function, the localized increase in GD3 may not only denote reactive glial cells but may contribute directly to the altered, hyperexcitable condition of epilepsy.     

Differential adhesivity of neuroepithelial cells and pioneering circumferential axons

To determine the initial growth pattern of pioneering axons and investigate the factors that may influence their guidance, the lateral margin of a stage 16+ chick brachial spinal cord was examined in serial thin sections. The specimen was prepared with hypertonic fixative which partially shrank the tissue and increased extracellular space. The retention of surface contact after shrinkage was used as an index of the relative adhesiveness between cells in situ. Six axons and growth cones were found within the reconstructed tissue; five were oriented dorsoventrally and one apparent motor neuron growth cone was oriented radially. The five circumferential axons originated from presumptive interneurons distributed in a dispersed pattern along the neural tube lateral wall. Four terminated with growth cones, and each extended a short distance (less than 30 microns) ventrally along the outer margin. No contact was found between these nonfasciculating axons or growth cones. Thus, the earliest intracentral axons appear to grow dorsoventrally from the outset with no appreciable wandering. Morphological features that may indicate their mechanism of guidance, including preformed cellular guides, extracellular channels, contact with basal lamina, and intercellular junctions were not found. The preferential retention of surface contact between adjacent endfeet, as well as between pioneering circumferential axons and neuroepithelial cells, suggests that these particular surfaces are mutually adherent. These findings are consistent with a proposed dorsal-to-ventral adhesive gradient mechanism of circumferential axonal guidance.     

Survival and transport of bacteria in egg washwater.

An evaluation of methods for monitoring the quality of water used to wash eggs at grading stations was undertaken to improve maintenance of bacterial viability during overnight sample transport. Bacterial content of samples at analysis would then better reflect conditions at the time eggs were washed. The interactive effects of temperature and the highly alkaline water conditions upon viability were the subjects of this study. Nine transport methods were examined for their efficacy in recovering total and coliform bacteria from recycled water used to wash eggs, and these were compared with samples analyzed at two commercial egg grading stations. Samples were shipped under test to the laboratory for analysis the following day. The survival of Staphylococcus aureus and Escherichia coli was also examined, but in a synthetic washwater matrix under various combinations of temperature (6 to 32 degrees C) and pH (9.5 to 10.5) to determine whether there was likely to be a different response to variations in transport treatment among gram-positive and -negative bacteria. S. aureus was much more resistant to the lethal effects of high pH and moderate temperature than E. coli. These results indicated that samples of high pH should be held (transported) at less than or equal to 13 degrees C to optimize bacterial survival. Considering cost, ease of manipulation, and the ability to protect both coliforms and the bacterial population as a whole, the method of choice for transport of industrial samples was the direct addition of washwater to containers in which powdered KH2PO4 and Na2S2O3 had been placed to yield final concentrations, when dissolved, of 0.2 and 0.05% (wt/vol), respectively.     

Strain and sex differences in the response of mice to drugs that induce protoporphyria: role of porphyrin biosynthesis and removal

A hepatic green pigment, inhibitory toward ferrochelatase, has been isolated from the liver of mice treated with griseofulvin, isogriseofulvin, or 3,5-diethoxycarbonyl-1,4-dihydrocollidine and has been shown to exhibit identical chromatographic characteristics to authentic N-methyl protoporphyrin. All four possible structural isomers have been demonstrated, and each drug produced primarily the same isomer. N-Methyl protoporphyrin has also been found in very small amounts in the liver of untreated mice, but the isomeric composition appeared to differ from that of the drug-induced N-methyl protoporphyrin. Intraperitoneal administration of 3,5-diethoxy-carbonyl-1,4-dihydrocollidine to female C3H/He/Ola and NIH/Ola inbred mice produced a marked dose-related loss of hepatic ferrochelatase activity, which was identical in magnitude in the two strains. Induction of hepatic 5-aminolevulinate synthase (ALA-S), and accumulation of liver protoporphyrin, however, were greater in C3H/He/Ola mice. The strain difference in ALA-S response was most marked when inhibition of ferrochelatase (the "specific" effect of the drug) was maximal, and this suggests that a genetic variation exists in the sensitivity of ALA-S to a second drug action, the so-called nonspecific action, which is shared by many lipid-soluble compounds. Male mice of three strains accumulated greater amounts of hepatic protoporphyrin than females after treatment with griseofulvin, yet no significant difference was found between the two sexes in the extent of ferrochelatase inhibition. Stimulation of ALA-S activity was slightly greater in males, but when porphyria was very marked, ALA-S activities were significantly lower in this sex.(ABSTRACT TRUNCATED AT 250 WORDS)     

NAD metabolism in Salmonella typhimurium: isolation of pyridine analogue supersensitive (pas) and pas suppressor mutants

Mutants of Salmonella typhimurium supersensitive to the nicotinic acid analogue 6-amino-nicotinic acid (6ANA) were isolated as unable to grow on what are normally subinhibitory concentrations of the analogue. The mutations were classified on the basis of their map positions as pasA (89-92 units), pasB (66-69 units), pasC (18-22 units), pasD (18 units) and pasE (55 units). The mutants exhibited a wide range of minimal inhibitory concentrations towards 6ANA, and several were affected in terms of growth. The data suggest that most of the mutations probably reside in genes whose products utilize nicotinamide adenine dinucleotide (NAD) as a cofactor, the altered gene products being more sensitive to internal 6-amino NAD concentrations. Secondary mutations which suppress the Pas- phenotype were found to reside in the following NAD-related loci; pncB, nadB and nadD. Two of the pncB mutants appear to be affected in the expression of NAPRTase while several of the nadB mutants are apparently insensitive to feedback inhibition by internal NAD concentrations.     

Cell shape, spatial patterns of cilia, and mucus-net construction in the ascidian endostyle

The endostyle of the ascidian Ciona intestinalis secretes a mucus-net composed of regularly spaced longitudinal and transverse mucoprotein filaments. It is a gutter-shaped organ composed of eight different longitudinally aligned epithelial zones numbered 1-8. Each zone, with the exception of zone 7 which is unciliatcd. has a characteristic cell shape and spatial pattern of cilia and microvilli. Zones 1.5 and 8 are composed of multiciliated cells, and zones 2,3,4 and 6 of monociliated cells. Cell apices in zones 2, 3 and 4 are rectangular in cross-section, and bear highly ordered rows of cilia. Spacings between cilia both within and between rows are different in each of these zones, but they are similar to interfilament spacings in the mucus-net. The basic structure of the mucus-net is probably secreted and constructed by secretory cells and cilia in zones 1-4. Further secretion may be added in zones 6 and 7 whilst cilia in zones 5, 6 and 8 propel the net out on to the inner surface of the pharynx where it acts as a food filter. The highly organized and structurally complex pattern of ciliated cpithelia in the aseidian endostyle is surprising when compared with the endostyle of the cephalochordate Branchiostoma lanceolatum, which is composed entirely of monociliated cells that differ very little in structure between epithelial zones.     

Frog olfaction: odour groups, acceptor distribution and receptor categories

A numerical matrix of electrophysiological data on odour discriminationin frog's olfactory receptors has been published by Revial etal. (1978). Pearson's "r" correlation coefficient and Benzecri's"analyse des correspondences" were used to analyse the informationcontained in the original matrix about similarities betweenodours and between receptors. Data analysis revealed five factorsthat accounted for 71% of the total variance, with one factormarkedly prevailing over the other four. Camphoraceous compoundswere opposed to aromatic compounds with respect to this firstfactor. Four groups of odorants were evidenced: i—an aromaticgroup including benzene, anisole, bromobenzene and dichlorobenzene;thiophenol seems to be related to this group; ii—a camphoraceousgroup with camphor and cineole; iii—a group includingcyclohexanol, cyclohexanone and tert-butyl alcohol; iv—afatty acid group with butyric, valeric and isovaleric acids.In addition, a sulphur group represented by thiophene is suggested.The functional implications of the groups are discussed. Itis proposed that a group is due to a number of types of acceptorsites sharing some common, sterical and energetical properties.Receptor cells combine multiple sensitivities and, consequently,do not fall under simple categories.     

Binding, internalization, and degradation of epidermal growth factor by balb 3T3 and BP3T3 cells: relationship to cell density and the stimulation of cell proliferation.

Epidermal growth factor (EGF) stimulates the growth of both benzo[a]pyrene-transformed Balb 3T3 cells (BP3T3) and untransformed Balb 3T3 cells. We describe here the binding, internalization, and degradation of [125I]-EGF by BP3T3 cells and 3T3 cells. Binding of [125I]-EGF reaches a maximum after 45 to 90 minutes incubation at 37 degrees C. In both BP3T3 and 3T3 cells the extent of EGF binding required to stimulate DNA synthesis is density dependent; sparse cultures require a 15-30% occupancy to elicit a maximal response whereas dense cultures require a 70-85% occupancy. At physiological concentrations the total binding of [125I]-EGF to 3T3 cells is higher than to BP3T3 cells, and this difference increases at higher cell densities. The rate of degradation of [125I]-EGF is directly proportional to the total [125I]-EGF binding in each cell type. This supports the hypothesis that one cause of the diminished serum requirement of BP3T3 cells is a reduced rate of utilization of serum growth factors.     

Problems of being a cell in a soft body

Many soft bodied coelenterates are highly deformable or contractile. In the absence of hard skeletal elements, the epithelia are subjected to mechanical forces which cause a wide range of structural changes in the component epithelial cells. What kinds of structural change occur and how are the cells adapted to them? These questions are addressed with reference to cell surface area, cell membranes, cell junctions and epithelial cilia.