Interaction of inflammatory cells and oral microorganisms. IV. In vitro release of lysosomal constituents from polymorphonuclear leukocytes exposed to supragingival and subgingival bacterial plaque

The deposition of bacterial plaques on tooth surfaces appears to be responsible for the initiation and progression of periodontal disease. In this study, human peripheral blood polymorphonuclear leukocytes (PMNs) actively released lysosomal constituents upon in vitro exposure to either viable or irradiated, supragingival or subgingival dental plaque. Plaques were obtained from the PMN donors (autologous plaque) or from pooled samples (homologous plaque) secured from patients with periodontal lesions. Fresh sera from PMN donors amplified the release reactions to supragingival and subgingival plaques. Heated (56 degrees C, 30 min) sera also enhanced release reactions, but not as consistently as fresh serum. It was postulated that modulation of PMN release by serum is mediated by complement components and/or antibodies to plaque bacteria. Electron microscopic observations indicated that degranulation and discharge of PMN lysosomal enzymes may be associated with phagocytosis of gram-positive and gram-negative plaque bacteria and with reverse endocytosis of lysosomes from cells contacting relatively large masses of aggregated plaque bacteria. These data suggest that PMN lysosome release in response to plaque may serve as a potential mechanism of tissue injury in the pathogenesis of gingival and periodontal inflammation.

Experimental toxemia in the pregnant primate

In order to develop a model for the study of eclamptogenic toxemia, a series of experiments were carried out on 31 female baboons. In Group 1, consisting of 10 animals, metal clips were placed around the uterine arteries in order to partially occlude them, and the ovarian vessels were transected. The animals were subsequently mated. Nine developed hypertension and proteinuria, and one aborted. The renal lesions in these animals were indistinguishable from those described in human toxemia. Group 2 consisted of three of the 10 baboons from Group 1, which became pregnant a second time. They again developed hypertension and proteinuria. In Group 3, three baboons at 100 days of gestation were treated as in Group 1 with similar results. Groups 4 and 5 served as pregnant (3) and nonpregnant (15) controls. It is concluded that a toxemia model has been developed in a subhuman primate. This model will prove useful in the further study of eclamptogenic toxemia.

Mutagen-nucleic acid intercalative binding: structure of a 9-aminoacridine: 5-iodocytidylyl(3'-5')guanosine crystalline complex

9-Aminoacridine forms a crystalline complex with the dinucleoside monophosphate, 5-iodocytidylyl(3'-5')guanosine. We have solved the three-dimensional structure of this complex by x-ray crystallography and have observed two distinct intercalative binding modes by this drug to miniature Watson-Crick double helical structures. The first of these involves a pseudosymmetric stacking interaction between 9-aminoacridine molecules and guanine-cytosine base-pairs. This configuration may be used by 9-aminoacridine when intercalating into DNA. The second configuration is an asymmetric interaction, largely governed by stacking forces between acridine and guanine rings. This type of association may play an important role in the mechanism of frameshift mutagenesis.

Organization of DNA in chromatin

Conformational changes in DNA that accompany drug intercalation have led us to ask if DNA first bends or "kinks" to accept an intercalative drug or dye. Kinking is made possible by altering the normal C2' endo deoxyribose sugar ring puckering in B DNA to a mixed sugar puckering pattern of the type C3' and partially unstacking base-pairs. A kinking scheme such as this would require minimal stereochemical rearrangement and would also involve small energies. This has prompted us to ask more generally if a conformational change such as this could be used by proteins in their interactions with nucleic acids. In this papter we describe an interesting superhelical DNA structure formed by kinking DNA every 10 base-pairs. The structure may be used in the organization of DNA in chromatin.

Drug-nucleic acid interaction: X-ray crystallographic determination of an ethidium-dinucleoside monophosphate crystalline complex, ethidium: 5-iodouridylyl(3'-5')adenosine

The intercalative trypanosomal drug, ethidium bromide, forms a crystalline complex with the dinucleoside monophosphate, 5-iodiuridylyl(3'-5')adenosine (iodoUpA). These crystals are monoclinic, space group C2, with unit cell dimensions, a = 2.845 nm, b = 1.354 nm, c = 3.413 nm, beta = 98.6 degrees. The structure has been solved to atomic resolution by Patterson and Fourier methods, and refined by full matrix least squares to a residual of 0.29 on 2017 observed reflexions. The asymmetric unit contains two ethidium molecules, two iodoUpA molecules, twenty water molecules and four methanol molecules, a total of 156 atims excluding hydrogens. The two iodoUpA molecules are held together by adenine-uracil Watson-Crick base-pairing. Adjacent base-pairs within this paired iodoUpA structure and between neighbouring iodoUpA molecules in adjoining unit cells are separated by 0.68 nm. This separation results from intercalative binding by one ethidium molecule and stacking by the other symmetry is utilized in this model drub-nucleic acid interaction, the intercalative ethidium molecule being oriented such that its phenyl and ethyl groups lie in the narrow groove of the miniature nucleic acid double helix. Solution studies have indicated a marked sequence specificity for ethidium-dinucleotide interactions and a probable structural explanation for this has been provided by this study.

X-ray crystallographic visualization of drug-nucleic acid intercalative binding: structure of an ethidium-dinucleoside monophosphate crystalline complex, Ethidium: 5-iodouridylyl (3'-5') adenosine

We have cocrystallized the drug ethidium bromide with the dinucleoside monophosphate 5-iodouridylyl(3'-5')adenosine and have solved the three-dimensional structure to atomic resolution by x-ray crystallography. This has allowed the direct visualization of intercalative binding by this drug to a fragment of a nucleic acid double helix.

Heterophile antibodies and tissue injury. 3. A role for platelets in the development of lethal vascular injury during Forssman shock in guinea pigs

Platelets appear to be pathogenetic determinants in the development of lethal Forssman shock, which was provoked in guinea pigs by an intravenous injection of rabbit antiserum to sheep erythrocyte stromata. Within moments, circulating platelets (prelabeled with (14)C-serotonin) were removed from the blood stream and impacted in the lungs, where they liberated (14)C into the tissues. When animals were depleted of platelets prior to the production of shock, they survived for prolonged periods of time or were protected against death. Pretreatment with antiinflammatory compounds capable of inhibiting platelet aggregation and release phenomena had a similar protective influence. It would appear, therefore, that Forssman shock is a convenient and accessible model for investigating the mechanisms whereby platelets mediate immune vascular damage.

Heterophile antibodies and tissue injury. 1. Ultrastructure of pulmonary vascular lesions produced by Forssman antiserum in guinea-pigs

The ultrastructural features of pulmonary vascular lesions were studied in guinea-pigs subjected to lethal Forssman shock. Within moments after an intravenous injection of Forssman antiserum the endothelia of venules and capillaries exhibited a wide range of morphological changes. Relatively mild lesions were characterized by the appearance of focal erosions in the cell membrane, cytoplasmic swelling and vacuolization. Severe lesions were associated with overt necrosis and disintegration of the endothelial lining, leaving the basement membrane in direct communication with the intravascular compartment. Platelets and PMN-leucocytes were consistently found to be adhering to denuded or damaged vascular surfaces and forming thromboembolic obstructions within blood channels. These data support the concept that vascular endothelium is a primary target tissue in Forssman shock. In addition, our findings suggest that platelets and PMN-leucocytes may be pathogenetic determinants in the development of Forssman shock.

The effect of ovariectomy on gonadotropin release

The sequential changes in the concentration and pattern of circulating luteinizing hormone (LH) and follicle-stimulating hormone (FSH)(1) following bilateral ovariectomy were determined in 10 premenopausal women. The initial (1st wk) and delayed (3 wk) secretory responses of serum LH and FSH as related to the phases of the menstrual cycle were examined. Ovariectomy during follicular phase was accompanied by a prompt and much greater rise in both LH and FSH during the 1st wk. This rapid rise was followed by a transient decline between the 7th and 10th day which resulted in a biphasic pattern. In contrast, a slower and progressive rise in serum LH and FSH was observed in subjects ovariectomized during luteal phase of the cycle. The quantitative secretion (area under the curve) during the 1st wk after ovariectomy was significantly greater in patients operated on during the follicular phase than during the luteal phase for both LH (P < 0.05) and FSH (P < 0.01). Thereafter, a similar pattern of gonadotropin rise was observed for patients ovariectonized during either phase of the cycle and reached a plateau by the end of the 3rd wk. At this time, the mean LH concentration increased 6-fold for follicular phase surgery and 8-fold for luteal phase surgery. The mean serum FSH concentration increased 8-fold for follicular phase surgery and 12-fold for luteal phase surgery. The net increase in serum FSH level was higher than that in the serum LH level after surgery in both phases of the cycle and thus a reversal of FSH/LH ratio occurred. These data provide indirect evidence that the phase of ovarian steroid secretion may exert a quantitative influence on the gonadotropin turnover rate within the hypothalamic-pituitary system. The augmented gonadotropin release and the reversal of FSH/LH ratio following ovariectomy presumably could be due to an increased gonadotropin net synthesis which is more pronounced for FSH than for LH.