Tooth pulp tissue promotes neurite outgrowth from rat trigeminal ganglia in vitro

The mammalian tooth pulp becomes innervated by nociceptive and sympathetic axons relatively late during development, when part of the root has formed. In the adult, regenerating axons from an injured tooth nerve or sprouting axons from uninjured nerves in the vicinity rapidly reinnervate denervated tooth pulps. These observations indicate that tooth pulp tissue can use molecular factors to attract pulpal axons from local nerve trunks. The present study examines the hypothesis that these factors include nerve growth factor (NGF), brain derived neurotrophic factor (BDNF) and glial cell line derived neurotrophic factor (GDNF). Explants of trigeminal ganglia from neonatal rat pups showed a distinct neurite outgrowth when co-cultured with pulpal explants collected from molar teeth of 12-day old pups, or after application of a pulpal extract. Control cultures, containing single ganglionic explants, or explants co-cultured with heat-treated pulpal tissue, exhibited a sparse neurite outgrowth. Exogenous NGF and/or GDNF, but not exogenous BDNF, stimulated neurite outgrowth from ganglionic explants. Unexpectedly, application of antibodies against NGF, BDNF and/or GDNF to co-cultures of ganglionic and pulpal explants did not inhibit neuritogenesis. Control experiments showed that IgG molecules readily penetrate the gel used for culture and that even very high concentrations of NGF and GDNF antibodies in combination failed to block neurite growth. On the basis of these data we suggest that other as yet unknown neurite-promoting factors might be present and active in TG/pulpal co-cultures.     

Mutations in C10orf11, a Melanocyte-Differentiation Gene,Cause Autosomal-Recessive Albinism

Autosomal-recessive albinism is a hypopigmentation disorder with a broad phenotypic range. A substantial fraction of individuals with albinism remain genetically unresolved, and it has been hypothesized that more genes are to be identified. By using homozygosity mapping of an inbred Faroese family, we identified a 3.5 Mb homozygous region (10q22.2–q22.3) on chromosome 10. The region contains five protein-coding genes, and sequencing of one of these, C10orf11, revealed a nonsense mutation that segregated with the disease and showed a recessive inheritance pattern. Investigation of additional albinism-affected individuals from the Faroe Islands revealed that five out of eight unrelated affected persons had the nonsense mutation in C10orf11. Screening of a cohort of autosomal-recessive-albinism-affected individuals residing in Denmark showed a homozygous 1 bp duplication in C10orf11 in an individual originating from Lithuania. Immunohistochemistry showed localization of C10orf11 in melanoblasts and melanocytes in human fetal tissue, but no localization was seen in retinal pigment epithelial cells. Knockdown of the zebrafish (Danio rerio) homolog with the use of morpholinos resulted in substantially decreased pigmentation and a reduction of the apparent number of pigmented melanocytes. The morphant phenotype was rescued by wild-type C10orf11, but not by mutant C10orf11. In conclusion, we have identified a melanocyte-differentiation gene, C10orf11, which when mutated causes autosomal-recessive albinism in humans.     

The Ciliated Brain Duct of Oikopleura dioica (Tunicata,Appendicularia)

Transmission electron microscopy revealed varying morphology of the dorsal part of the duct indicating the occurrence of different stages of activity. In some animals the tip cavity contains an amorphous substance which, at another phase of activity, is released into the surrounding hemocel through interstices in the walls of the tip. A transitional zone separates the dorsal tip from the large ventral part of the duct, where the wall, near the transitional zone, consists of a single layer of thin cells joined by tight junctions. Ventrally, the large ciliated cells lie in two levels near the opening into the buccal cavity. They bear numerous, tightly packed cilia which beat vigorously in living animals. The organization of this part resembles that of protonephridia. An excretory function is suggested for this part of the duct.     

Measurement of in situ rates of nitrification in sediment

A method has been developed for the measurement of nitrification rates in intact sediment cores without disturbing the concentration gradients of oxygen and ammonium. N-serve (2-chloro-6-trichloromethyl-pyridine), a specific inhibitor of the autotrophic ammonium oxidation, was injected into a 0–2 cm surface layer of the sediment (20 ppm) and added to the water column of sediment cores (5 ppm). N-serve in these concentrations was sufficient to inhibit nitrification, but did not change the rate of ammonium production or incorporation in sediment suspensions, which were incubated aerobically and anaerobically. The ammonium accumulation in cores injected with N-serve was thus equal to the amount of ammonium which was oxidized to nitrate in the control cores. Nitrification rates were in the range of 0–3 mmol N m^{–2 –1}     

The masticatory handicap of wearing removable dentures in elderly men

Objective: This study aimed at describing the masticatory handicap of wearing removable dentures measured by some masticatory tests and the intake of hard and soft foods. Materials and methods: The subjects were participants in a comprehensive health examination of 67–68‐year‐old men living in Malmö, Sweden. Four hundred eighty‐three men took part in a clinical oral examination which recorded the number of teeth and removable dentures. One hundred and one had complete dentures in both jaws and 131 had removable partial dentures in different combinations. Masticatory tests used almonds to record the number of stokes to the first swallow, and two‐coloured chewing gums for recording bolus kneading and shaping. A nutritionist paid a home visit to assess dietary habits including the consumption of hard and soft foods. The data could be split into groups of different tooth and denture situations which were large enough to enable statistical analysis to be carried out. The results of a regression analysis of the group with different numbers of natural teeth (NT) and no removable dentures could be used as a reference for correlation with the masticatory capacity of removable denture wearers. Results: Number of strokes to the first swallow revealed no masticatory limitations of wearing removable dentures, while chewing gum colour‐mixing and shaping revealed more differentiated impairments equivalent to the function of five to 16 teeth in a remaining natural dentition. Hard food intake for the removable denture groups was comparable to 17–19 NT. Soft food intake was not influenced by denture wearing. In a ranking of oral conditions, those with more than 24 NT had the highest test values for all tests, and those with complete sets of dentures the lowest except for the number of strokes to the first swallow of an almond. Conclusion: Removable denture wearing can be regarded as a handicap when measured with objective masticatory tests using chewing gum and the intake of hard foods. The number of chewing strokes to the first swallow of an almond and the intake of soft foods is not affected by the wearing of removable dentures.     

Graph-representation of oxidative folding pathways

Background  

The process of oxidative folding combines the formation of native disulfide bond with conformational folding resulting in the native three-dimensional fold. Oxidative folding pathways can be described in terms of disulfide intermediate species (DIS) which can also be isolated and characterized. Each DIS corresponds to a family of folding states (conformations) that the given DIS can adopt in three dimensions.     

Cerebrospinal fluid levels of free 3-nitrotyrosine are not elevated in the majority of patients with amyotrophic lateral sclerosis or Alzheimer's disease

The mechanisms behind the degeneration of neurons in diseases such as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS) are not fully understood. However, oxidation of certain amino acid residues in proteins may contribute to cell injury and some of these oxidized amino acids may also be suitable as biomarkers for oxidative injury. Therefore, it is suggested that the reaction between peroxynitrite (ONOO(-)) and tyrosine in vivo can be monitored by monitoring the formation of 3-nitrotyrosine (3-NT). In this work, a newly developed gas chromatographic-mass spectrometric method was applied to human cerebrospinal fluid (CSF). The free 3-NT levels were determined in the CSF from 19 controls, 17 patients with AD and 14 patients with ALS. The levels of free 3-NT in the CSF were considerably lower than those previously reported. The majority of the patients with AD or ALS had free 3-NT levels in the same range as seen in the control individuals and only a few patients showed increased levels of free 3-NT.     

Structural membrane alterations in Alzheimer brains found to be associated with regional disease development; increased density of gangliosides GM1 and GM2 and loss of cholesterol in detergent-resistant membrane domains

The formation of neurotoxic beta-amyloid fibrils in Alzheimer's disease (AD) is suggested to involve membrane rafts and to be promoted, in vitro, by enriched concentrations of gangliosides, particularly GM1, and the cholesterol therein. In our study, the presence of rafts and their content of the major membrane lipids and gangliosides in the temporal cortex, reflecting late stages of AD pathology, and the frontal cortex, presenting earlier stages, has been investigated. Whole tissue and isolated detergent-resistant membrane fractions (DRMs) were analysed from 10 AD and 10 age-matched control autopsy brains. DRMs from the frontal cortex of AD brains contained a significantly higher concentration (micromol/micromol glycerophospholipids), of ganglioside GM1 (22.3 +/- 4.6 compared to 10.3 +/- 6.4, p <0.001) and GM2 (2.5 +/- 1.0 compared to 0.55 +/- 0.3, p <0.001). Similar increases of these gangliosides were also seen in DRMs from the temporal cortex of AD brains, which, in addition, comprised significantly lower proportions of DRMs. Moreover, these remaining rafts were depleted in cholesterol (from 1.5 +/- 0.2 to 0.6 +/- 0.3 micromol/micromol glycerophospholipids, p <0.001). In summary, we found an increased proportion of GM1 and GM2 in DRMs, and accelerating plaque formation at an early stage, which may gradually lead to membrane raft disruptions and thereby affect cellular functions associated with the presence of such membrane domains.     

Reactivation of Delta–Notch Signaling after Injury: Complementary Expression Patterns of Ligand and Receptor in Dental Pulp

The evolutionarily conserved Notch-mediated intercellular signaling pathway is essential for proper embryonic development of many tissues and organs. Recent data suggest that Notch receptors and their membrane-bound ligands Delta and Serrate are involved in both patterning and cell fate determination during odontogenesis. It remains, however, uncertain if Notch signaling is important for tooth homeostasis and regeneration. Here we report on the expression of Notch receptors and the Delta1 ligand in dental pulp of normal and injured adult rat teeth. Notch receptors were absent from normal adult dental tissues, whereas expression was upregulated after injury. In injured teeth, Notch2 was expressed in mesenchymal cells of the pulp both close to the site of injury (i.e., in the dental crown) and at a distance from it (i.e., in the dental roots), Notch3 expression was mainly associated with vascular structures, while Notch1 expression was restricted to few pulpal cells close to the lesion. None of them was expressed in odontoblasts. Expression of Delta1 was upregulated in odontoblasts of the injured teeth, as well as in vascular structures. These results demonstrate the reactivation of the Notch signaling pathway during wound healing and, furthermore, highlight the similarity between developmental and regenerative processes.     

Reproductive structures of an extinct platanoid from the early Cretaceous (latest Albian) of eastern North America

Two new species of platanoid reproductive structure are described from the Bull Mountain locality in the Patapsco Formation (Potomac Group) of northeastern Maryland, USA. Pistillate inflorescences and infructescences (Platanocarpus elkneckensis sp. nov.) consist of flowers and fruits in sessile globose heads that are borne on an elongate axis. Individual pistillate flowers consist of five free carpels surrounded by prominent tepals. Staminate inflorescences, flowers and isolated stamens are assigned to Hamatia elkneckensis gen. et sp. nov. Staminate flowers are borne in a globose head with a small number of stamens (five?) per flower. Stamens consist of very short filaments, long anthers with strongly valvate dehiscence and an apically expanded connective. The connective expansion is frequently very well-developed, hook-like and extends down the ventral surface of the stamen. Anthers contain small, tricolporate, reticulate pollen. Association evidence, similarity of inflorescence structure and the occurrence of Hamatia-type pollen on flowers, carpels and fruits of Platanocarpus elkneckensis suggests that the staminate and pistillate material was produced by a single species of plant. The “Hamatia-plant” provides further evidence of pentamerous floral structure in mid-Cretaceous platanoids and documents the occurrence of unequivocal tricolporate pollen in the platanoid complex.