An N-terminal peptide from link protein is rapidly degraded by chondrocytes, monocytes and B cells

A peptide cleaved from the link-protein component of human and pig proteoglycan aggregates by trypsin and stromelysin was taken up and degraded further by human monocytes, B cells, chondrocytes and by mouse peritoneal macrophages. Monocytes were able to process the peptide twice as rapidly as peritoneal macrophages and some 16 times more rapidly than articular chondrocytes. The B cell line Priess, which unlike the monocytes and macrophages could not take up or degrade whole proteoglycan aggregates, was able to degrade the peptide at a rapid rate. Synthetic, unglycosylated peptides consisting of the first 16 and 13 N-terminal amino acids of human link protein, corresponding to its stromelysin-cleavage and trypsin-cleavage products, were also taken up and degraded in a similar manner to the natural products and, in addition, were able to block uptake of the 125I-labelled natural peptides. The isoelectric points of the re-secreted breakdown fragment from both the synthetic and natural peptides were identical and each peptide was processed by the cells to produce a single radiolabelled fragment. Each of these fragments was eluted with the same retention time during HPLC, indicating that the natural peptides were derived from the N-terminal region of the link. Since a proportion of the link protein extracted from human and pig cartilage has already undergone proteolysis to remove peptides from its N-terminal region, these peptides may be produced in articular cartilage during the normal process of turnover and ageing. Although a physiological function for this protein has not been established, it may have a homeostatic role in the regulation of proteoglycan synthesis.

Rapid release of an alpha-adrenergic receptor ligand from photolabile analogues

A series of 2-nitrobenzyl derivatives of the alpha 1-selective adrenergic agonist, L-phenylephrine [(R)-N-[2-(3-hydroxyphenyl)-2-hydroxyethyl]-N-methylammonium chloride], have been synthesized and characterized for the purpose of developing biologically inert compounds that can be rapidly converted to L-phenylephrine by near-UV irradiation. The compounds, derivatized on the phenolic oxygen, were O-(1-(2-nitrophenyl)ethyl)phenylephrine (I), O-(2-nitrobenzyl)phenylephrine (II), O-(4,5-dimethoxy-2-nitrobenzyl)phenylephrine (III), and O-(alpha-carboxyl-2-nitrobenzyl)phenylephrine (IV). All four compounds photolyzed to free phenylephrine following a brief exposure to 300-350-nm light or 347-nm laser light with steady-state quantum yields ranging from 0.05 to 0.28. The rates of phenylephrine formation on photolysis were estimated from the decay rates of aci-nitro intermediates detected by absorbance between 380 and 500 nm. Compound IV displayed the highest quantum yield (0.28) and most rapid photolysis rate (1980 s-1) measured under near physiological conditions, pH 7.0, 22 degrees C. Biological properties of the compounds were examined in smooth muscle from rat caudal artery. Laser pulse photolysis of IV at 347 nm initiated a maximal contraction in Krebs buffer, pH 7.1, 25 degrees C, that mimicked the response to 50 microM phenylephrine but was faster in onset. Photoinitiated contractions were characterized by a delay of 0.93 +/- 0.09 s followed by a rising phase with a 10-90% rise time of 3.56 +/- 0.17 s (n = 7). Responses were fully blocked by the alpha 1-selective antagonist prazosin.(ABSTRACT TRUNCATED AT 250 WORDS)

Proliferating cell nuclear antigen (PCNA) in atypical and malignant meningiomas

Because it is not easy to determine the tumor status of meningiomas by current diagnostic procedures, we investigated these tumors immunohistochemically using the monoclonal antibody PC 10. This antibody recognizes a fixation- and processing-resistant epitope of the proliferating cell nuclear antigen (PCNA), which is a 36-KD nuclear antigen associated with the cell cycle. We studied paraffin-embedded and formalin-fixed tissue specimens of a group of 21 atypical/malignant meningiomas together with 18 benign meningiomas. PCNA staining results were compared with the mean number of silver-stained nucleolar organizer region-associated proteins (AgNORs), tumor grading, and mitotic indices of these tumors. The percentage of PCNA-positive cells was found to range between 0.1% and 40%, irrespective of the tumor grade. When all tumors were collectively considered, no positive correlation was found between PCNA scores and histologic grading and only a weak one between PCNA score and mitotic index. A higher correlation was seen between AgNOR counts and tumor grading. Our results suggest that PCNA labeling and histologic grading seem to be independent parameters. The correlations found between AgNOR counts and tumor grading should be substantiated in further series.

Histomorphometric comparison of canals prepared by four techniques

Numerous methods of root canal preparation have been recommended and used by clinicians. This study used histomorphometrics to determine the area of root canal preparations using four currently popular techniques. Clinicians that were highly skilled in each technique prepared curved canals in acrylic blocks. Each clinician described this technique and discussed the technique with regard to the use of acrylic blocks as compared with dentin. Analysis of the areas of the root canals after preparation revealed a significant difference among the groups. The mean areas after treatment were step-back technique, 17.33 mm2; Cavi-Endo technique, 15.87 mm2; Canal Master technique, 13.56 mm2; and balanced force technique, 17.31 mm2. Photographs of the blocks used in the study were included for inspection by the reader.

Comparative effects of a recommended lipid-lowering diet vs a diet rich in monounsaturated fatty acids on serum lipid profiles in healthy young adults

This crossover study investigated the effects of two fat-reduced diets, one rich in monounsaturated fatty acids (MUFAs), the other rich in polyunsaturated fatty acids (PUFAs), on serum lipid profiles in 38 healthy young adults initially on a typical western diet. After being randomly assigned to two groups, the subjects received the MUFA or PUFA diet for 3-wk and then the other diet for 3 wk. Both test diets led to significant reductions in serum cholesterol, LDL cholesterol, and HDL cholesterol (P less than 0.001). Both reduced apolipoprotein B (P less than 0.001) and apolipoprotein A-I concentrations (P less than 0.01 for the MUFA, P less than 0.001 for the PUFA diet). Apolipoprotein A-I was significantly higher on the MUFA than on the PUFA diet. The ratio of apolipoprotein A-I to B significantly increased on both diets. Thus, a low-fat, MUFA-rich diet is as effective as a low-fat, PUFA-rich diet in lowering total and LDL cholesterol, but both also lowered HDL cholesterol concentrations. The MUFA-rich diet may be more advantageous than the PUFA-rich one because it does not lower apolipoprotein A-I concentrations as much as the PUFA-rich diet.

Influence of preoperative dexamethasone therapy on proliferating cell nuclear antigen (PCNA) expression in comparison to other parameters in meningiomas

We conducted a trial in 42 benign and malignant meningiomas to assess a possible influence of preoperative dexamethasone therapy on mitotic index, labelling indices of proliferating cell nuclear antigen (PCNA), progesterone receptor, epidermal growth factor receptor (EGF-R), c-erbB-2 oncoprotein, cathepsin D, gamma-gamma enolase as well as the mean number of silver-stained nucleolar organizer region-associated proteins (AgNORs). Tumors with preceding dexamethasone therapy for more than 1 day display significantly less immunohistochemical staining for PCNA. A correlation between the labelling index of PCNA and the degree of malignancy could not be identified. There was no significant effect of preoperative dexamethasone therapy on the other parameters. Our data suggest that dexamethasone may selectively inhibit the expression of PCNA in the G1/S-phase of the cell cycle. Thus, we emphasize the necessity to heed factors, e.g. dexamethasone, which may affect the expression of proliferating markers.

Nucleolar organizer region-associated proteins in cancer cells. Quantitative investigations on gliomas, meningiomas, urinary bladder carcinomas and pleural lesions

Using a modified silver staining technique, we investigated nucleolar organizer region-associated proteins (AgNORs) in paraffin sections of 156 neoplastic tissues and other lesions, including gliomas (n = 41), meningiomas (n = 20), urinary bladder carcinomas (n = 58), and neoplastic and reactive lesions of the mesothelium of the pleural cavity (n = 37). We found significant differences in the mean number and area of AgNORs per nucleus between nonanaplastic and anaplastic astrocytomas. In meningiomas AgNOR analysis may be useful to distinguish between mostly benign tumors (grade 1 tumors) and atypical ones. Urinary bladder carcinomas exhibited a statistically significant increase in both AgNOR number and area as the grade of malignancy increased. Diagnostically useful differences in the AgNOR configuration between inflammatory and neoplastic processes were found for mesothelial lesions. In general, a higher grade of malignancy correlated with an increase in the AgNOR number. This was accompanied by an increase in the total AgNOR area per nucleus, irrespective of whether the size of the individual AgNORs had changed.

Karyotypes in 90 human gliomas

Cytogenetic studies were performed on 90 human gliomas including 26 astrocytomas, 12 oligodendrogliomas, three oligo-astrocytomas, seven ependymomas, eight pilocytic astrocytomas, and 33 malignant gliomas (anaplastic astrocytomas and glioblastomas). The most common abnormalities were trisomy 7 in 23 cases, monosomy 22 in 15 cases, losses of the Y chromosome in 19 of 50 male cases, and losses of the X chromosome in 10 of 39 female cases. There are evident differences between the particular subgroups of gliomas. Monosomy 10 and double minutes are typical for malignant gliomas. The 58 determined chromosomal breakpoints were located on 45 different sites. Chromosomes 1, 9, 6, 3, 10, and 17 were predominantly involved.

Serotonin-like immunoreactivity in Merkel cells and their afferent neurons in touch domes from the hairy skin of rats

Immunoreactivity to serotonin was observed in Merkel cells as well as the afferent type I nerves terminating upon them in touch domes excised from the belly skin of rats. Type I nerves were strongly immunoreactive and could be traced through the dermis of the domal papilla. Merkel cell immunoreactivity was sometimes seen in the entire cell, but was often localized in the Merkel cell cytoplasm adjacent to nerve terminals and may have been in the terminals themselves. Domes were fixed by immersion in 4% paraformaldehyde-lysine-sodium-m-periodate (PLP) fixative at 4 degrees C for 2.5-3 hours and cryoprotected in 30% sucrose overnight. Sections were processed with the avidin-biotin complex peroxidase (ABC), peroxidase-antiperoxidase (PAP), and indirect immunofluorescence techniques with rabbit antiserum generated against serotonin.

A proteolytic fragment from human link protein is taken up and processed by monocytes and B cells

Mild digestion of 125I-labelled human proteoglycan aggregates with trypsin or stromelysin produced specific peptides that were taken up rapidly by THP-1 monocytes. SDS/PAGE of undigested aggregate showed that the three components of molecular mass 48, 44 and 41 kDa, corresponding to isoforms of link protein originally present, had been converted into a single component of 41 kDa by trypsin treatment, and that fragments of 6-12 kDa were present in fractions containing the high-uptake peptide. Separate proteolysis of isolated proteoglycan monomer and link protein confirmed that the specific high-uptake fragment was derived from link protein. Uptake of the link fragment was rapid, reaching a maximum after 5 min, and specific, since it was blocked by metabolic or serine proteinase inhibitors and at 4 degrees C. After uptake the cleaved fragment was processed further, with 50% of the radiolabel being released as degraded peptides within 5 min. In contrast, accumulation of whole aggregate reached a maximum after 45 min and only 50% had been released after 2 h. Uptake of aggregate was less affected by inhibitors or at low temperature, suggesting that a separate mechanism existed for its turnover. The aggregate was transported to lysosomes after uptake, although the link fragment did not sediment with either lysosomes or plasma membranes, suggesting that it was present in the cytoplasm or in very labile vesicles. However, the mode of handling of the peptide by the cells remains unclear. The link fragment was taken up by several different monocytic and B cell lines, but not by mouse fibroblasts or peritoneal macrophages. These data suggest that a surface serine proteinase on monocytes and B cells enables them to process and take up a fragment of link protein derived by extracellular proteolysis.

Cleanliness, disinfection, and sterilization of the root canal

Disinfection is a key aspect in the preparation of root canals prior to obturation. Irrigation and intracanal medicaments are the chemical means of debridement. The bacterial role is significant, and intracanal medicaments must be cidal in their effect on bacteria and the dentinal tubules. Topical application of medicaments seem to be as effective or more effective than antibiotic applications. Glutaraldehyde and calcium hydroxide are two of the more recently studied medicaments. Calcium hydroxide shows promise as an effective microbicide. The importance of removal of bacteria and necrotic debris from the canal by chemomechanical means--mechanical preparation, cidal irrigation, antimicrobial medicaments--will enhance the successful outcome of endodontic therapy.