Fourier transform infrared (FTIR) spectroscopy has been used to explore the thermal unfolding of three helical, alanine-based peptides. Each of the peptides follows the general sequence Ac-(AAAX)nA-NH2 where X is either Lys+ or Arg+ and n = 3 or 4. These particular peptides were chosen because they contain varying amounts of 3(10)- and alpha-helix. The amide I' bands for all three peptides, under helix forming conditions, are between 1632 and 1635 cm-1. These results are incongruous with the assignment for alpha-helices in proteins where amide I' bands are usually found above 1650 cm-1. At elevated temperatures, all the peptides exhibit amide I' bands of 1642 cm-1, which is the accepted value for random coil. Variable temperature spectra for the 4K peptide (n = 4, X = Lys+), which is the most alpha-helical of the three peptides at 1 degree C, reveal an isosbestic point suggesting a cooperative two-state unfolding transition. The other peptides, however, did not reveal an isosbestic point, thereby indicating the presence of an intermediate, perhaps 3(10)-helix, along the thermal unfolding pathway.

Alanine↗

PubMedDate not supplied

Characterization of bones by speckle interferometry.

Speckle photography interferometry (SPI) is used to evaluate the stress-strain behaviour of animal bones under loads by recording the speckle fields generated on the bone surface and thus finding the relationship between the fractal dimension D(s) and the compression load P. The procedure consists of application of slow and monotonous compression loads, and recording of the deformation levels and vertical displacements of the specimen. A He-Ne laser beam directed at the surface of bone specimen produces light scattering which generates the speckle. The optical fields show significant differences before and after fracture, due to the changes of the bone surface generated by the strain. Our results support previous suggestions of a relationship between fractal characteristics and parameters related to the mechanical behaviour of materials.

Animals↗

PubMedDate not supplied

Expression of vimentin intermediate filament in human odontoblast.

BACKGROUND: Vimentin (57 Kda) is a cytoskeletal protein. Odontoblasts contain vimentin and it seems that this protein may function to keep the organelles and the nucleus in a definite place. However little is known about vimentin in the cytoskeleton of odontoblast processes. The purpose of the present study was, therefore to immunolocalize vimentin intermediate filament in odontoblast body and process in order to clarify the distribution of this cytoskeletal element. METHODS: 12 extracted intact premolars, from children, were used in the present study. Each specimen was decalcified in EDTA. Each tissue portion was embedded in paraffin. On sections a monoclonal anti-vimentin antibody was applied. The immunoreaction was visualized by ABC technique. RESULTS: Vimentin was expressed in the cell body and cell process of odontoblasts, however with a different immunolabeling pattern related to the topographical area of observations. In odontoblast cell bodies vimentin showed a perinuclear and cytoplasmatic staining. In the very initial portion of odontoblast process immunoreaction products for vimentin were observed in the core of the process. In the middle zone of dentin vimentin immunoreactions products also showed a granular and cross-bridge arrangements, and also, vimentin was also detected under the plasma membrane, at the periphery of the odontoblast process. Nearby the dentino-enamel junction vimentin immunolabeling was appreciated, mainly under the plasma membrane. CONCLUSIONS: On the basis of vimentin distribution in the odontoblast process it seems plausible to assume that this IF vimentin is important in forming a flexible scaffold essential for structuring cytoplasm.

Child↗

PubMedDate not supplied

[Histo-ontogenetic study of the major salivary glands and Chievitz's organ].

Salivary glands development has been studied by optical microscopy in 8 fetuses aged from 8 to 20 weeks of fetal life. From the observation of the sections obtained we can assume that submandibular gland is the first gland to be detectable, later the parotid gland and then the sublingual gland. In tight connection with the parotid gland Chievitz organ has been demonstrated. It is not known whether this organ may or may not contribute to parotid gland.

Cheek↗

PubMedDate not supplied

[Structure and ultrastructure of the human TMJ meniscus].

This ultrastructural study is concerned on demonstrating the presence and the distribution of the elastic system fibers in human TMJ disc. Oxytalan and pre-elastic fibers were found to occur in the anterior, intermediate and posterior band of the disc. These fibers run parallel to collagen fibers in the outer portion of the disc while in the deeper portion they were canted compared to collagen fibers arrangement. The presence of an elastic system fibers in human TMJ disc it is plausible to assume that it enables the disc to resist to a wider range of reversible deformation.

Cartilage, Articular↗

PubMedDate not supplied

[Histology of the cartilage of the human fetal condyle].

The Authors have examined with optical microscopy the articular cartilages from the supero-posterior area of the mandibular condyles of ten TMJ of 5 human fetuses. In this study have been shown the cellular components of the 3 outer areas of the condyle. Further it has been pointed out that the fibrous lining of the cartilage is not only composed of collagen fibrils, proteoglycans and fibroblasts but also contains elastic fibers.

Cartilage, Articular↗

PubMedDate not supplied

[Melanosomes, melanocytes and keratinocytes in the human epidermis in incontinentia pigmenti].

A functioning epidermal melanin unit implies a melanocyte capable of transferring melanosomes to keratinocytes; this requires not only melanocytes with adequate dendrites but also "receptive" keratinocytes. Skin with incontinentia pigmenti was examined by electron microscopy. Premelanosomes were occasionally found within keratinocytes and deposits of extracellular granular material that came from vacuolar degeneration of keratinocytes adjacent to melanocytes.

Humans↗

PubMedDate not supplied

[Light microscope study of human dental morphogenesis].

Human teeth morphogenesis was studied by optical microscopy from the 10th to 20th week of fetal life. Enamel, dentin and pulp development were analyzed. An important observation on mandibu teeth arises from this investigation that consists in a biforcation of mandibular ossification in two branches, this could allow to the teeth to develop inside the mandibular arch.

Dental Arch↗

PubMedDate not supplied

Non-productive or thalassemic-like heavy-chain gene rearrangement in a K-chain CLL clone.

Information obtained from the study of immunoglobulin (Ig) gene rearrangement in different types of lymphoproliferative disorders has led to the suggestion that Ig gene activation obeys a precise hierarchy in which heavy-chain gene rearrangement procedes light-chain gene recombination. However no information is available on the mechanism(s) controlling this sequential activation. We report here a case of CLL which suggests that the expression of the heavy-chain genes is not necessary for light-chain gene rearrangement, or that very low amounts of heavy-chain mRNA and/or heavy chains are sufficient to activate k-chain genes.

Aged↗

PubMedDate not supplied

[Changes in the TMJ in the intrauterine and extrauterine period of life].

The aim of this work is the study of hte prenatal and postnatal development of the human temporomandibular joint. Ten of human embryos and fetuses and six joint of young children were sectioned sagittally and frontally, decalcified where necessary and stained using Mallory and Cajall-Callengo techniques. At the eighteen gestational week the condylar blastema became evident, the temporal blastema appeared later. At the twenty-second week all the structure of the joint were present, but the morphogenesis was not completed as one could observe from the preparations the Meckel's cartilage. A key observation from the study of features and embryos was that the condylar cartilage wasn't uniformly distributed on the condylar surface bur it was located in posterior-lateral area. At birth TMJ showed some characteristics typical of this period such as : a flat temporal component a disc with blood vessels and a condyle with connective-vascular channels. These characteristics will disappear later in the life at about 3-5 years.

Female↗