Sorsa T, Uitto V-J, Suomalainen K, Vauhkonen M, Lindy S.: Comparison of interstitial coliagenases from human gingiva, sulcular fluid and polymorphonuclear leukocytes. J Periodont Res 1988: 23: 386-393. Mammalian coliagenases (EC 3.4,24,7) have been suggested as playing an essential role in the initiation of the collagen degradation in periodontal diseases. Two distinct types of interstitial coliagenases have been characterized in vertebrate tissues. These enzymes, the fibrobiast-and the neutrophil-type coliagenases,, differ in molecular weight and antigenic properties, as well as substrate specificity and mechanism of activation. In order to determine the cellular origin and mode of action of coliagenase in periodontal tissue, we studied the molecular size, the substrate specificity and the activation of coliagenases partially purified from inflamed human gingival extracts, sulcular fluid, gingival expiant culture medium and polymorphonuclear leukocytes (PMN). Types I, II and III collagens used as substrates were purifted from bovine tendon, cartilage and amnion membrane, respectively. Apparent molecular weights of 70-75 k were obtained for gingival extract, sulcular fluid and PMN coliagenases and 45 k for gingival expiant culture collagenase by gel filtration technique. The gingival extract and sulcular fiuid coliagenases as well as PMN collagenase could be activated by gold thioglucose and gold thiomalate; no activation of gingival expiant culture collagenase was noted. The gingival extract collagenase. sulcular fluid collagenase and PMN collagenase degraded preferentially types I and 11 collagens relative to type-Ill collagen. In contrast, gingival expiant culture coliagenase degraded preferentially types I and III collagens relative to type-II collagen. The results indicate that collagenase in extracts of inflamed human gingiva and in sulcular fluid during inflammation is mostly derived from PMN cells. On the other hand, collagenase produced by gingival explants in culture is probably synthesized by fibrobiasts.

The diagnosis of atrophic gastritis obtained with the blood test panel of S-G-17, S-PGI and H. pylori antibodies is in good agreement with the endoscopic and biopsy findings. The panel is a tool for non-endoscopic diagnosis and screening of atrophic gastritis.

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The lateral organization of fluid cholesterol-dimyristoylphosphatidylcholine (DMPC) bilayers was studied by measuring the response of fluorescent membrane probes, dipyrenylphosphatidylcholines (diPyrxPCs) or merocyanine 540, to the variation of cholesterol concentration. Parallel absorbance and light-scattering measurements were also carried out. The excimer-to-monomer ratio of diPyrxPCs displayed abrupt deviations at particular cholesterol mole fractions (CMFs). The most notable of these occurred at CMFs of 0.15, 0.33, and 0.67. Deviations were also frequently observed at CMFs of 0.12, 0.20, 0.25, and 0.40. Merocyanine 540 reproducibly reported deviations at CMFs of 0.15 and 0.33 and frequently reported values close to 0.12, 0.20, and 0.25. In absorbance (turbidity) and light scattering versus CMF plots, well-defined kinks were observed at CMFs of 0.16, 0.33, 0.52, and 0.67. The occurrence of kinks or other deviations at those particular CMFs is most readily explained in terms of a superlattice model previously developed to explain the lateral distribution of pyrenylphospholipids in bilayers [Somerharju, et al. (1985) Biochemistry 24, 2773-2781; Virtanen, J. A., et al. (1988) J. Mol. Electron. 4, 233-236]. This model is based on the assumptions that (i) each cholesterol molecule replaces a single acyl chain in a hexagonal lattice, (ii) cholesterol molecules, because of their larger size, perturb the lattice, (iii) this perturbation is minimized when the cholesterol molecules are maximally separated from each other, and (iv) the maximal separation is achieved when the cholesterol molecules form a hexagonal or centered rectangular superlattice. All detected critical CMFs, except that at CMF 0.67, are predicted by the model, thus strongly supporting its validity. The critical CMF at 0.67 is a limiting case, which can be accounted for by assuming that cholesterol and phospholipid molecules form alternating rows, i.e., formation of a cholesterol superlattice with rectangular symmetry. As predicted by the superlattice model, composition-driven order-to-disorder transitions occur between the critical CMFs, as indicated by increased data scatter and sample fluctuations in those regions. Another important prediction of the superlattice model is that domains with different cholesterol superlattices should coexist at most cholesterol concentrations. Such domains do not have to be extensive to account for the critical events observed here; rather, they are expected to be dynamic entities of limited size. It is very likely that such microscopic domains with distinct cholesterol superlattices also coexist in biological membranes. This is expected to have remarkable effects on both the structure and functions of these membranes.

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The lateral mobility of pyrenyl phospholipid probes in dimyristoylphosphatidylcholine (DMPC) vesicles was determined from the dependence of the pyrene monomeric and excimeric fluorescence yields on the molar probe ratio. The analysis of the experimental data makes use of the milling crowd model for two-dimensional diffusivity and the computer simulated random walks of probes in an array of lipids. The fluorescence yields for 1-palmitoyl-2-(1'-pyrenedecanoyl)phosphatidylcholine (py10PC) in DMPC bilayers are well fitted by the model both below and above the fluid-gel phase transition temperature (Tc) and permit the evaluation of the probe diffusion rate (f), which is the frequency with which probes take random steps of length L, the host membrane lipid-lipid spacing. The lateral diffusion coefficient is then obtained from the relationship D = fL2/4. In passing through the fluid-gel phase transition of DMPC (Tc = 24 degrees C), the lateral mobility of py10PC determined in this way decrease only moderately, while D measured by fluorescence photobleaching recovery (FPR) experiments is lowered by two or more orders of magnitude in gel phase. This difference in gel phase diffusivities is discussed and considered to be related either to (a) the diffusion length in FPR experiments being about a micrometer or over 100 times greater than that of excimeric probes (approximately 1 nm), or (b) to nonrandomicity in the distribution of the pyrenyl probes in gel phase DMPC. At 35 degrees C, in fluid DMPC vesicles, the diffusion rate is f = 1.8 x 10(8) s-1, corresponding to D = 29 microns2 s-1, which is about three times larger than the value obtained in FPR experiments. The activation energy for lateral diffusion in fluid DMPC was determined to be 8.0 kcal/mol.

In the intramolecular excimeric membrane probe, dipyrenylphosphatidylcholine (dipyn PC), pyrene moieties are linked to the terminal carbons of the two acyl chains, each of which contains n carbons. We show here how the probe intramolecular excimer production rate, K, may be determined from the excimer/monomer intensity ratio, rl, by making use of the fluorescence titrations of the related monopyrenyl probe, pyn PC, analyzed according to the milling crowd model. rl and the rate K of dipy10 PC in four model membrane systems were measured over a wide temperature range and both parameters are shown to be sensitive functions of the lateral fluidity of the host matrix. A model for relating the intramolecular and intermolecular excimer formation rates is proposed according to which both processes are limited by the reorientational rate of the pyrene moiety. Above the fluid-gel transition temperature, Tc, the diffusion rate (f) of the monopyrenyl probe (pyn PC) is accordingly related to K by: pE approximately K/(K + 1/2f + tau -1M), where pE is the probability of excimer formation between nearest neighbor pyn PC probes, and tau M is the monomer lifetime. Values of pE derived in this way are found to be consistent with pE values derived from the milling crowd analysis of fluorescence yield titration experiments. K for dipy10 PC in DMPC multibilayers ranges from 0.21 x 10(7) s-1 at 10 degrees C in the gel phase, to 5.7 x 10(7) s-1 at 60 degrees C in the fluid phase, whereas the lateral diffusion coefficient, D, for py10 PC in the same bilayers ranged from 8 to 34 microns2 s-1, when calculated with D = fL2/4, L being the average lipid-lipid spacing of the host membrane. Above Tc and at the same reduced temperature, (T - Tc)/Tc, both f for py10 PC, and K for dipy10 PC were found to have relative magnitudes in the order: DPPC greater than DMPC greater than POPC greater than DOPC. This and the similarity of the activation energies for f and K suggest that the rotation of the the pyrene moiety is the rate-limiting step for both the lateral mobility of py10 PC and intramolecular excimer formation in dipy10 PC.