Identification and structural and functional characterization of human enamelysin (MMP-20)

A cDNA encoding a new human matrix metalloproteinase (MMP) has been cloned from RNA prepared from odontoblastic cells. The open reading frame of the cloned cDNA codes for a polypeptide of 483 amino acids and is extensively similar to the sequence of recently described porcine enamelysin, suggesting that the isolated cDNA codes for the human homologue of this enzyme. Human enamelysin (MMP-20) has a domain organization similar to other MMPs, including a signal peptide, a prodomain with the conserved motif PRCGVPD involved in maintaining enzyme latency, a catalytic domain with a Zn-binding site, and a COOH-terminal fragment similar to the sequence of hemopexin. The calculated molecular mass of human enamelysin is about 54 kDa, which is similar to that of collagenases or stromelysins. However, this human MMP lacks a series of structural features distinctive of these subfamilies of MMPs. The full-length human enamelysin cDNA has been expressed in Escherichia coli, and the purified and refolded recombinant protein is able to degrade synthetic peptides used as substrates of MMPs, confirming that human enamelysin belongs to this family of proteases. Furthermore, the recombinant human enamelysin is able to degrade amelogenin, the major protein component of the enamel matrix. On the basis of its degrading activity on amelogenin, and its highly restricted expression to dental tissues, we suggest that human enamelysin plays a central role in the process of tooth enamel formation. Finally, we have found that the human enamelysin gene (MMP-20) maps to chromosome 11q22, clustered to at least seven other members of the MMP gene family.     

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The muscarinic acetylcholine antagonist scopolamine impairs short-distance homing pigeon navigation

The present study employed intramuscular (i.m.) injections of the acetylcholine (ACh) receptor antagonist scopolamine hydrobromide (0.10 mg/kg) to investigate the possible involvement of ACh in naturally occurring spatial navigation in homing pigeons (Columba livia). Control pigeons receiving injections of saline or scopolamine methylbromide, an ACh antagonist that does not cross the blood-brain barrier, were oriented in a homeward direction when released from a location 8 km from home. In contrast, pigeons injected with scopolamine hydrobromide (0.10 mg/kg, i.m.) were less well oriented and took more time to return home from the same location. These results suggest that homing pigeon navigation is regulated, in part, by central cholinergic mechanisms.     

Antioxidant activity and free radical-scavenging capacity of a selection of wild-growing Colombian plants

BACKGROUND: The replacement of some synthetic food antioxidants by safe natural antioxidants has fostered research on the screening of raw materials to find new vegetable sources of antioxidants. In this study the antioxidant activity of eight wild‐growing Colombian plants was assessed by four complementary assays. RESULTS: An evaluation of the antioxidant activity of ten ethanolic extracts from Baccharis chilco, Cinnamomum triplinerve, Ilex laurina, Lachemilla orbiculata, Lepechinia conferta, Quercus humboldtii, Rubus urticifolius and Tephrosia cinerea was carried out. Furthermore, the total phenolic content was determined by the Folin–Ciocalteu method, and the relationship between phenolic content and activity was also statistically investigated. Cinnamomum triplinerve, L. conferta and I. laurina were found to have the highest phenolic contents. Baccharis chilco, C. triplinerve, I. laurina, L. conferta, Q. humboldtii and R. urticifolius showed higher radical‐scavenging activity (DPPH and superoxide assays) than commercial rosemary oleoresin (reference). Lachemilla orbiculata and R. urticifolius showed higher antioxidant activity (β‐carotene‐bleaching test) than the reference. The protection factor of all studied plant extracts was below that of the reference according to the Rancimat test. CONCLUSION: On the basis of the results obtained, C. triplinerve, Q. humboldtii and R. urticifolius seem to be the most promising species for further investigation in order to identify the compounds responsible for their activity. Copyright © 2011 Society of Chemical Industry     

Irrational beliefs, optimism, pessimism, and psychological distress: a preliminary examination of differential effects in a college population

A study was made of the prevalence of voice disorders and their risk factors in teaching professionals of Logro?o, Spain. A prevalence and case-control study was made, including interviews, ENT examination, videostrobolaryngoscopy, perceptual evaluation of hoarseness, basic aerodynamic tests, the physical range of phonation, and a physical analysis of the acoustic signal. The prevalence of voice disorders among Logro?o teachers was 17.7% (confidence interval: 12.1-25%). Nodular lesions (8.1%) were the most frequent pathology, followed by hyperfunctional dysphonia (4.1%), chronic laryngitis (2.7%), polyps (1.4%), hypofunctional dysphonia (0.7%), and submucous suffusion (0.7%). Voice disorders were more prevalent in women (19.3%) than in men (15.6%), and among teachers of the lowest grades: 36.4% in nursery schools, 25% in elementary school, and 20.8% in junior school. The width and depth of classrooms, larger number of students, longer classroom hours, and noise level were related with the frequency of voice disorders.     

Peptide amidating activity in human bronchoalveolar lavage fluid

Monitoring respiratory epithelial biology may reveal individuals with incipient lung cancer. The expression of neuroendocrine (NE) markers in pulmonary epithelium is thought to be central to lung development, repair of injury and may contribute to carcinogenesis. In this study, we evaluate several candidate NE markers to determine the feasibility of prospective analysis of clinical specimens. The potential NE markers include the enzyme L-DOPA decarboxylase (DDC), the neuropeptide gastrin releasing peptide (GRP), and peptidyl-glycine alpha-amidating monooxygenase (PAM), the bifunctional enzyme responsible for the final bioactivation step of many neuropeptides. A comparison of PAM activity and DDC levels in 30 lung cancer cell lines indicated that peptide amidating activity may be an indicator of NE status. Bronchoalveolar lavage (BAL) fluid from subjects at risk of developing second primary lung cancer and from volunteers was obtained. The activity of the first PAM enzyme, peptidylglycine alpha-hydroxylating monooxygenase (PHM), ranged from not detectable to 507 pmol/h/mg protein in 57 specimens. The second PAM enzyme, peptidylamidoglycolate lyase (PAL), ranged from not detectable to 414 pmol/h/mg protein in 56 specimens. Using cluster analysis by the average linkage method, a group of enzyme values with PHM greater than 230 pmol/h/mg protein was determined. Long-term follow-up of these patients for new second primary lung cancers may help to determine the potential predictive value of PAM detected in the BAL fluid.     

The Peyer's patch high endothelial receptor for lymphocytes, the mucosal vascular addressin, is induced on a murine endothelial cell line by tumor necrosis factor-alpha and IL-1

The specificity of lymphocyte homing from the blood into a tissue is determined in part by complementary pairs of adhesion receptors on lymphocytes and endothelial cells termed homing receptors and vascular addressins, respectively. The mucosal vascular addressin involved in lymphocyte homing to Peyer's patches is a 66-kDa glycoprotein, MAdCAM-1. Investigation of the regulation and molecular genetics of MAdCAM-1 have been hampered by the lack of a murine cell line expressing this adhesion molecule. We show herein using indirect immunofluorescence studies that MAdCAM-1 can be induced on a murine endothelial cell line, bEnd.3, by cytokines and LPS. Western blot analysis of MAdCAM-1 purified by affinity column chromatography from TNF-alpha-treated bEnd.3 cells demonstrates a 66-kDa protein that comigrates in SDS-PAGE with the MAdCAM-1 constitutively found on high endothelial venules in murine mesenteric lymph nodes. Comparison of MAdCAM-1 expression on the bEnd.3 cells was made to the expression of adhesion molecules ICAM-1 and VCAM-1. MAdCAM-1 and VCAM-1 are not constitutively expressed on the bEND.3 surface but can be induced in a concentration-dependent manner by LPS, TNF-alpha, and IL-1. ICAM-1 is constitutively expressed on the endothelioma surface and expression is increased by TNF-alpha, IL-1, LPS, and IFN-gamma. Surface expression of MAdCAM-1 peaks 12 to 18 h after exposure to TNF-alpha and remains elevated at 48 h, whereas expression of VCAM-1 peaks at 4 h and inducible ICAM-1 peaks between 4 and 18 h. Interestingly, IFN-gamma has differential effects on expression of these three adhesion receptors. IFN-gamma alone induces VCAM-1 and enhances ICAM-1 expression, but does not induce MAdCAM-1. Furthermore, although, preincubation of bEND.3 cells with IFN-gamma modestly increases the induction of ICAM-1 and VCAM-1 in response to TNF-alpha and IL-1, it dramatically reduces the TNF-alpha, IL-1, and LPS-induced expression of MAdCAM-1. MAdCAM-1 on bEnd.3 cells is functional as the murine T lymphoma TK1, known to bind MAdCAM-1, also binds to TNF-alpha-stimulated endothelioma but not to unstimulated cells. This binding is blocked by the antibodies against MAdCAM-1 and against the alpha 4-chain of its integrin receptor, alpha 4 beta 7, on TK1 cells.(ABSTRACT TRUNCATED AT 400 WORDS)