Changes in the incidence of periodontal pathogens during long-term monitoring and after application of antibacterial drugs.

The incidence of potential periodontal pathogens (Aggregatibacter actinomycetemcomitans, formerly Actinobacillus actinomycetemcomitans, Tannerella forsythia, Porphyromonas gingivalis, Prevotella nigrescens, Prevotella intermedia and Capnocytophaga ochracea) was monitored in patients with chronic periodontitis and in healthy control subjects. Two types of studies were carried out in which the composition of the bacterial communities in different niches of the same oral cavity ecosystem was investigated. Fluctuation or at least pronounced quantitative changes in the incidence of individual species in time were documented in the long-term study as well as after the local administration of antibacterial drug Chlo-Site or Metronidazole. Even within two weeks, a turnover of the monitored bacteria in separate niches of the oral biotope can be detected. A relatively high incidence of the tested periopathogens in the clinically healthy teeth of patients implies that even the "healthy" niches in the periodontal biotope function as a dynamic reservoir of periopathogenic microorganisms. This should be kept in mind when a local application of antibacterial compounds is used in the therapy of periodontal disease.

Interleukin- 1 gene polymorphisms as assessed in a 10-year study of patients with early-onset periodontitis.

Our 10-year study of early-onset periodontitis (EOP) patients includes repeated clinical observations, microbiological characteristics and analysis of genetic polymorphism of IL-1A and IL-1B genes. Twenty patients (age 15-26 years) were divided according to the clinical status in the 4th year into a group with mean number of teeth with bleeding on probing (BP) 9.8 and mean number of teeth with periodontal pocket (PP) 2.23, and a group with mean number of teeth with BP 5.37 and no PP. Significantly higher values of mean BP and PP were found among the groups during the study but a strong progression of disease was found only in 3 patients. The risk IL-1A allele-2 and IL-1B allele-2 genotype and bacterial presence were analyzed by DNA hybridization methods. No significant differences of bacteria composition (Treponema denticola, Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans) were found between the groups. A higher prevalence of composite IL-1 genotype was detected in the group of EOP patients with progressive disease. Early finding of the disease followed by conservative therapy could positively influence the disease progression. EOP treated in early stages may, but need not, develop into the aggressive form in the presence of risk genotype IL-1.

Effect of prostaglandin E2 on the ductus arteriosus in the newborn rat. An ultrastructural study.

A patent ductus arteriosus (DA) was maintained in newborn rats (Wistar strain) by administering prostaglandin E2 (PG E2) in doses of 15 micrograms.kg-1 at 30 min intervals up to 300 min after birth. In the control animals, the DA was functionally closed 300 min after birth. The lumen was blocked by clustered endothelial cells at various stages of degeneration. Elastic membranes of the media had disintegrated into irregular fragments and the smooth muscle cells were contracted. Cytoplasm excrescences formed on their surface as a result of contraction protruded as hernias into adjacent muscle cells and into endothelial cells. The smooth muscle cells degenerated. The administration of PG E2 inhibited contraction of the smooth muscle cells and so also the development of degenerative changes; 300 min after birth the DA was fully patent, the elastic membranes were structurally intact, regularly organized and continuous. The smooth muscle cells had the character of synthesizing cells with richly developed granular endoplasmic reticulum. The intima and its endothelial lining were likewise free from structural changes. The ultrastructural image of the wall of the DA correspondent to the state 10 min after birth, when the DA was fully patent. The administration of PG E2 did not induce any ultrastructural changes indicative of injury to the wall of the DA.

Effect of the administration of prostaglandins (PGE2) in the early postnatal period on closure of the ductus arteriosus in the laboratory rat.

Maintenance of a patent ductus arteriosus by means of prostaglandins enables the surgical correction of a congenital heart defect in infants to be postponed until a phase of development when the operation hazards are smaller. We investigated the pathophysiological consequences of this therapeutic measure in an experimental model in which E2 prostaglandin was administered to newborn laboratory rats. It was found that, physiologically, the ductus arteriosus (DA) closed progressively within 180 min after birth. The repeated administration of PGE2 (subcutaneously, 15 micrograms.kg-1 every 30 min from the 5th min after birth) blocked closure of the DA, which was still fully patent 300 min after birth. Histological tests showed no significant differences in the structure of the tunica media of the physiologically patent and the PGE2-treated DA. The results show that PGE2 also inhibit physiological closure of the DA in newborn rats. Long-term study of this pathophysiological process is at present impeded by the need for the continuous administration of prostaglandins.

The physiological closure of ductus arteriosus in the rat. An ultrastructural study.

The evolution of morphological changes in the wall of the ductus arteriosus during its physiological closure in newborn rats was examined by electron microscopy. The contraction of smooth muscle cells in the tunica media seems to be the primary mechanism which leads to the physiological closure of the ductus arteriosus. For this reason our attention was centred mainly on the morphology of the tunica media. No important changes in the ultrastructure of smooth muscle cells can be observed in the early phases of the closure. Most of them exhibit ultrastructural features of cells with enhanced synthetic activity during all phases of the closure. The permanent contraction of smooth muscle cells results in their morphological changes. The most striking is the herniation of smooth muscle cell cytoplasm into the endothelial and later into adjoining muscle cells. These changes together with signs of degeneration of the smooth muscle cells are already clearly discernible 120 min after birth. The elastic component of the tunica media exhibits surprisingly fast changes. As soon as 60 min after birth, the fragmentation of elastic membranes and their structural changes provided evidence about the degradation of elastic material. The matrix vesicles, probably derived from the lysosomal apparatus of the muscle cells, may play an essential role in this process.

Different effect of propranolol and verapamil on isoprenaline-induced changes in the chick embryonic heart.

Isoprenaline (IPRO) has been reported to cause pathological lesions of the embryonic heart. The purpose of the present study was to ascertain whether the development of IPRO-induced changes can be reduced--similarly as in adults--by beta blockade or calcium antagonists. IPRO was administered to 10-day-old chick embryos intraamnially (i.a.) in a dose of 2 X 10 mg.kg-1 per 48 h; propranolol (Inderal) and verapamil (Isoptin) were injected i.a. in a dose of 1.0 or 10.0 mg.kg-1 before each injection of IPRO. It was found that propranolol completely blocked the cardiac IPRO-induced changes, i.e. cardiomegaly, avascular areas and elevation of cAMP. On the other hand, verapamil was found to have no protective effect in any dose used. Furthermore, it increased the mortality of experimental embryos. This fact support the hypothesis that cardiac sensitivity to calcium antagonists may differ during prenatal development.

Calcium antagonists and the developing heart.

Ontogenetic differences in cardiac sensitivity to calcium antagonists were studied in chick embryonic and postnatal immature rat heart. It has been found that verapamil exhibits no protective effect on isoprenaline-induced changes of the chick embryonic heart. Furthermore, it increased the mortality of experimental embryos. The mortality of verapamil-treated rats was age-dependent, increasing with decreasing age of animals. Similarly, the intensity of negative inotropic response of the isolated right ventricular myocardium and isolated perfused rat heart was significantly greater in the youngest age groups. These results point to the possible negative consequences of the clinical use of calcium antagonists during the early phases of ontogeny.

The effect of oxidized isoprenaline on the chick embryonic heart.

Intra-amnial administration of isoprenaline (IPRO) to chick embryos induces a number of myocardial lesions. The purpose of the present study was to investigate whether similar changes may also be induced after injection of spontaneously oxidized isoprenaline and commercially obtained adrenochrome. Cardiotoxicity of these substances has been demonstrated in adult animals. IPRO, oxidized IPRO, or adrenochrome were administered intra-amnially to 10-day-old chick embryos at doses of 0.1, 1.0, 10.0, and 100.0 mg X kg-1. Parallel experimental groups received propranolol at a dose of 1 mg X kg-1, 15 s before injection of IPRO or oxidized IPRO. The cAMP level in the heart was determined by radioimmunoassay 2 and 30 min after administration of IPRO, oxidized IPRO, or adrenochrome at a single dose of 10.0 mg X kg-1. It has been found that in embryos the effect of IPRO and oxidized IPRO is dose dependent. The rise in mortality and development of cardiomegaly together with increased hydration and disturbances of the development of coronary vascularization were highly significant starting from the dose of 10 mg X kg-1. Furthermore, both drugs significantly increased cAMP levels in the embryonic heart. On the other hand, the administration of adrenochrome was without any effect. The changes induced by IPRO were prevented by the administration of the beta-blocking agent propranolol; the lesions induced by spontaneously oxidized IPRO were, however, prevented only partially.

Analysis of the cardiotoxic effect of isoproterenol in chick embryo.

Intraamnial administration of isoproterenol (IPRO) to chick embryo induces different types of pathological changes of the myocardial and liver tissue: their character depends upon the developmental period during which the drug was administered. Analysis of the embryotoxic effect of IPRO has revealed that the time-course of in vivo uptake of [3H]IPRO by the developing heart appears to present the same pattern as the embryonic liver tissue; both peak values (10 min and 6 h after injection) were, however, significantly higher in the liver as compared with the myocardium. IPRO is rapidly metabolized to 3-o-methyl-IPRO; the proportion of this fraction in both organs represents approximately 40% of total radioactivity as early as 5 min after administration. Intraamnial administration of IPRO significantly increases the cAMP content in the myocardium; dibutyryl cAMP-induced myocardial lesions occurred, however, only occasionally and in comparison with IPRO they were significantly less pronounced. The cardiotoxic effect of IPRO can be significantly reduced by beta-blockade; calcium antagonist, verapamil, was found to have no protective effect. Our results suggest that the following factors may participate in the IPRO-induced embryotoxicity: (1) IPRO, (2) its toxic metabolites, (3) cAMP.