Titer and subclass distribution of serum IgG antibody reactive with Actinobacillus actinomycetemcomitans in localized juvenile periodontitis

Most patients with localized juvenile periodontitis (LJP) manifest serum IgG antibodies specifically reactive with antigens of Actinobacillus actinomycetemcomitans serotype b (Aa-b). Whether these antibodies are protective, destructive, or irrelevant to the progress of the disease remains unclear. We report results of studies aimed at assessing the subclass IgG responses in 35 LJP patients and 35 periodontally normal control subjects using well-characterized monoclonal antibody subclass reagents in an enzyme-linked immunosorbent assay. Our data show that the mean value for total IgG reactive with antigens of Aa-b was more than sevenfold higher for patients than for normal control sera (2349.6 micrograms/ml for patients vs 332.2 micrograms/ml for controls). Individual patients and control subjects were classified as high- or low-titer, using twice the median value for total anti-Aa-b IgG in control sera as the cutoff. Of 35 patients, 26 (74%) were high-titer, and 9 (26%) were low-titer. This compares to 5 normal control subjects (14%) high-titer and 30 (86%) low-titer. IgG2 accounted for the major quantitative response in both patients and control subjects. Indeed, the mean IgG2 values for both concentration and percentage of total specific IgG were greater than the combined values for specific anti-Aa-b IgG1, IgG3, and IgG4. Of the 26 high-titer sera, IgG2 predominated in 24, with IgG1 and IgG3 predominating in 1 each; IgG2 predominated in only 2 of the low-titer sera.     

Attachment loss and serum antibody levels against autologous and reference strains of Actinobacillus actinomycetemcomitans in untreated localized juvenile periodontitis patients

Immunological data have been suggested to be a potential tool in the diagnosis, classification and monitoring of periodontal diseases. However, the role of circulating antibodies in periodontal patients is poorly understood. Patients suffering from localized juvenile periodontitis (LJP) are often reported to show high titers of serum IgG antibodies against Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans), but several affected patients do not. Most studies use well-known reference strains of the bacterium for testing against the patients' sera. The aim of the present investigation was to study the relationship between serum IgG antibody levels to autologous A. actinomycetemcomitans strains and clinical attachment loss (CAL). In addition, we wanted to assess the patients' serum titers against 4 well-known reference strains of the bacterium as well as their general potential immunoglobulin response. Intravenous blood samples were taken from 23 LJP patients and 10 healthy individuals, and autologous A. actinomycetemcomitans strains were cultured from 18 of the LJP patients. CAL was measured at 4 different sites around all present teeth and assessed as a % of teeth with at least 1 site moderately > or = 2 < 5 mm) or severely (> or = 5 mm) involved. An enzyme-linked immunosorbent assay (ELISA) was performed to evaluate the serum titers of IgG antibodies to A. actinomycetemcomitans antigens. No significant correlation was found between serum IgG antibody titers to autologous strains and CAL. However, there was a trend that low responders had more moderately affected teeth than had high responders and patients with undetectable A. actinomycetemcomitans levels, which is in agreement with a hypothetically protective role of the antibodies. The total counts of immunoglobulin assessed in all participants showed that the predominant class was IgG and the reference group displayed significantly less (p < 0.05) IgG and IgG1 counts than the LJP patients. Both the reaction pattern against reference and autologous strains varied widely. We conclude that the specific antibody response against A. actinomycetemcomitans shows a weak correlation to clinical attachment levels in LJP patients.     

Serum antibodies to Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in juvenile periodontitis and adult periodontitis (part I)

Recent microbiological studies support the concept that specific gram negative bacteria play a major role in the etiology and pathogenesis of human chronic inflammatory periodontal disease. Actinobacillus actinomycetemcomitans has been isolated frequently from juvenile periodontitis and Porphyromonas gingivalis has been shown to be a prominent species in adult periodontitis in humans. The purpose of this study was to determine levels of the specific antibodies to A.actinomycetemcomitans and P.gingivalis in 17 patients with juvenile and 15 patients with adult periodontitis and 24 healthy subjects. IgG and IgM antibody titers against these antigens were determined by enzyme-linked immunosorbent assay (ELISA). The levels of antibodies against A.actinomycetemcomitans were significantly higher in the juvenile periodontitis compared to the adult periodontitis patients and controls. Anti-P.gingivalis antibodies were elevated in adult periodontitis compared to juvenile periodontitis patients and controls.     

Subcellular localization and cytotoxic activity of the GroEL-like protein isolated from Actinobacillus actinomycetemcomitans

The subcellular locations, ultrastructure, and cytotoxic activity of the GroEL-like protein from Actinobacillus actinomycetemcomitans were investigated. Two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) clearly indicated that synthesis of the GroEL-like protein is substantially increased after a thermal shock. Analysis of the purified native GroEL-like protein by transmission electron microscopy revealed the typical 14-mer cylindrical molecule, which had a diameter of about 12 nm. A. actinomycetemcomitans cells grown at 35 degreesC and heat shocked at 43 degreesC were fractionated, and fractions were separated by SDS-PAGE and analyzed by Western immunoblotting using antibodies to GroEL- and DnaK-like proteins. The GroEL-like protein was found in both the soluble and membrane fractions, whereas the DnaK-like protein was mostly found in the cytoplasm. An increase in specific proteins, including the GroEL- and DnaK-like proteins, was found in heat-shocked cells. The subcellular localization of the GroEL-like protein was examined by immunoelectron microscopy of whole cells. More GroEL-like protein was detected in stressed cells than in unstressed cells, and most of it was found not directly associated with outer membranes but rather in extracellular material. The native GroEL-like protein was assessed for cytotoxic activities. The GroEL-like protein increased the proliferation of periodontal ligament epithelial cells at concentrations between 0.4 and 1.0 microgram/ml. The number of cells in the culture decreased significantly at higher concentrations. A cell viability assay using HaCaT epithelial cells indicated that the GroEL-like protein was strongly toxic for the cells. These studies suggest the extracellular nature of the GroEL-like protein and its putative role in disease initiation.     

Binding of the capsule-like serotype-specific polysaccharide antigen and the lipopolysaccharide from Actinobacillus actinomycetemcomitans to human complement-derived opsonins

We investigated the molecular mechanism of resistance of Actinobacillus actinomycetemcomitans to complement-dependent chemiluminescence response by human polymorphonuclear leukocytes. Whole cells of serotype b-specific polysaccharide antigen-defective mutants ST2 and ST5 were constructed by inserting transposon Tn916 into A. actinomycetemcomitans strain Y4. These strains induced strong chemiluminescence response by human polymorphonuclear leukocytes and markedly bound to human complement-derived opsonins. In contrast, strain Y4 induced weak chemiluminescence response and weakly bound to complement-derived opsonins. The biosensor analysis revealed that lipopolysaccharide from strain Y4 strongly bound to human C3b, but serotype b-specific polysaccharide antigen did not. The serotype b-specific polysaccharide antigen molecule might sterically hinder the interaction between complement-derived opsonins and lipopolysaccharide to reduce complement-dependent chemiluminescence response by human polymorphonuclear leukocytes.     

LPS from Actinobacillus actinomycetemcomitans and production of nitric oxide in murine macrophages J774

Nitric oxide (NO) plays a complex role in the modulation of the inflammatory response, having either a pro-inflammatory or a protective role. Actinobacillus actinomycetemcomitans is considered an important etiological agent in localized juvenile periodontitis. We have studied the effect of lipopolysaccharide (LPS) extracted from this periodontopathogenic bacterium on NO synthesis in an in vitro murine macrophage system. LPS from A. actinomycetemcomitans induced a significant production of NO even at concentrations as low as 1 ng/ml, whereas LPS from E. coli had to be added in concentrations of 100 ng/ml to obtain similar effects. Production of NO was blocked by NG-nitro-L-arginine methylester, and pre-treatment of LPS from A. actinomycetemcomitans with polymyxin B abolished the production of NO, while prostaglandin E2 enhanced the synthesis of NO.     

Cloning and sequencing of part of the S10 operon from Actinobacillus actinomycetemcomitans FDC Y4

Linear dye penetration was evaluated in teeth with open apices in which calcium phosphate cement was used as an apical barrier to facilitate obturation. The apical foramens of 42 extracted single-rooted human teeth were opened to a size 90 file. Half the teeth received apical barriers consisting of calcium phosphate cement (CPC) followed by obturation using a customized gutta-percha cone/ lateral condensation technique. The other half were obturated without benefit of apical barriers. Linear dye penetration was measured after 48 h exposure to India ink. The teeth receiving apical CPC barriers before obturation had significantly less dye penetration than teeth without apical barriers. Based on its proven biocompatibility and osteconductive potential, calcium phosphate cement may serve well as a replacement for calcium hydroxide in a single-visit immediate apical barrier apexification technique.     

Epidemiology and transmission of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans among children and their family members. A report of 4 surveys

The distribution and transmission of Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans in 4 families were studied. The families were included, based on the isolation of P. gingivalis from a young child or adolescent. The probands of these 4 families were: a 5-year old periodontally healthy boy; a 17-year old girl with severe generalized juvenile periodontitis; an 11-year old girl with prepubertal periodontitis; 2 sisters, 5 and 17-years old, with untreated severe periodontitis as a component of the Papillon-Lefèvre syndrome. All members of the 4 families were examined clinically and microbiologically for the presence of P. gingivalis and A. actinomycetemcomitans. Most of the parents appeared to be adult periodontitis patients; the parents of one proband were edentulous. Results showed that in all cases at least one of the parents was positive for P. gingivalis. On the basis of indistinguishable restriction endonuclease patterns (REPs) of P. gingivalis and A. actinomycetemcomitans isolates from parents and their children, and distinct REPs from unrelated individuals, the present study indicates that P. gingivalis and A. actinomycetemcomitans were transmitted between parents and their children.     

The effects of periodontal therapy on serum antibody levels to Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis (part II)

Levels of IgG and IgM antibodies were estimated against Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis were determined by enzyme linked immunosorbent assay (ELISA) in 17 patients with juvenile periodontitis, 15 with adult periodontitis and 24 healthy controls at the beginning of treatment and 3 to 8 months after periodontal therapy. After treatment, antibodies to A. actinomycetemcomitans and P.gingivalis had decreased in patients, but the levels were still significantly higher than in healthy controls. Whether or not an of antibody level against a specific bacteria changes after periodontal treatment is however, still debatable.     

Relationship of structure and function of the avian respiratory system to disease susceptibility

The avian respiratory system exchanges oxygen and carbon dioxide between the gas and the blood utilizing a relatively small, rigid, flow-through lung, and a system of air sacs that act as bellows to move the gas through the lung. Gas movement through the paleopulmonic parabronchi, the main gas exchanging bronchi, in the lung is in the same direction during both inspiration and expiration, i.e., from the mediodorsal secondary bronchi to the medioventral secondary bronchi. During inspiration, acceleration of the gas at the segmentum accelerans of the primary bronchus increases gas velocity so it does not enter the medioventral secondary bronchi. During expiration, airway resistance is increased in he intrapulmonary primary bronchus because of dynamic compression causing gas to enter the mediodorsal secondary bronchi. Reduction in air flow velocity may decrease the efficiency of this aerodynamic valving and thereby decrease the efficiency of gas exchange. The convective gas flow in the avian parabronchus is orientated at a 90 degree angle with respect to the parabronchial blood flow; hence, the cross-current designation of this gas exchanger. With this design, the partial pressure of oxygen in the blood leaving the parabronchus can be higher than that in the gas exiting this structure, giving the avian lung a high gas exchange efficacy. The relationship of the partial pressure of oxygen in the moist inspired gas to that in the blood leaving the lung is dependent on he rate of ventilation. A low ventilation rate may produce a ow oxygen partial pressure in part of the parabronchus, thereby inducing hypoxic vasoconstriction in the pulmonary arterioles supplying this region. Inhaled foreign particles are removed by nasal mucociliary action, by escalator in the trachea, primary bronchi, and secondary bronchi. Small particles that enter parabronchi appear to be phagocytized by the epithelial cells in eh atria and infundibulum. These particles can e transported to interstitial macrophages but the disposition of the particles from this site is unknown. The predominant site of respiratory infections in the caudal air sacs, compared to other parts of the respiratory system, can be explained by the gas flow pathway and the mechanisms present in the parabronchi for particle removal.     

Involvement of prostaglandin E2 and interleukin-1 alpha in the differentiation and survival of osteoclasts induced by lipopolysaccharide from Actinobacillus actinomycetemcomitans Y4

Lipopolysaccharide (LPS) is a bacterial cell component that plays multifunctional roles in inflammatory reactions. LPS from various periodontal pathogens is supposed to be a major virulence factor of periodontal diseases. In the present study, we demonstrated that LPS from periodontopathic bacterium Actinobacillus actinomycetemcomitans Y4 (Y4 LPS) stimulated osteoclast formation in mouse bone marrow culture systems. Addition of anti-interleukin-1 alpha (IL-1 alpha) antibody or indomethacin in the marrow cultures resulted in the suppression of osteoclast differentiation. Quantitative analyses revealed that Y4 LPS stimulated the production of IL-1 alpha and prostaglandin E2 (PGE2) by bone marrow cells. Furthermore, an immunoblot analysis showed that Y4 LPS stimulated bone marrow cells to upregulate the expression of cyclooxygenase-2, a rate-limiting enzyme for the conversion of arachidonic acid to prostanoids. These findings suggest that both IL-1 alpha and PGE2 are involved in the LPS-mediated osteoclast differentiation. In addition, we found that Y4 LPS supported the survival of osteoclasts. Addition of anti-IL-1 alpha antibody in the osteoclast culture resulted in a reduction of osteoclast survival. Indomethacin, however, showed no effect on osteoclast survival. These findings suggest that the increased PGE2 and IL-1 alpha synthesis by bone marrow cells may play an important role in the differentiation and survival of osteoclasts induced by A. actinomycetemcomitans LPS.     

Relationship between physical structure and machinability of green compacts

Abstract

The dependence of green machinability on compact density and strength was investigated for room temperature and warm compacted steel powder compacts containing two different types of lubricant. Brazilian disc compression tests were employed to determine green strength, while machinability was assessed in terms of response to drilling.

For the room temperature compacted materials, it was found that high compact densities and strength were not, in most cases, associated with improvements in machinability. Furthermore, it was shown that lubrication (both type and quantity) and compaction pressure plays a critical role in determining the level of breakouts observed. In contrast, the use of warm compaction, in conjunction with specially designed lubricants, has been shown to be a suitable method of producing high density, high strength compacts while retaining good green machining characteristics. Mechanisms responsible for the observed behaviours of both the room temperature and warm compacted specimens have been forwarded in the present paper.     

梯度硬质合金结构与性能的关系

采用真空烧结-渗碳处理工艺制备了梯度结构硬质合金,通过力学性能测试、物理性能测试和光学显微分析研究了渗碳处理前的真空烧结工艺和渗碳处理时间对合金抗弯强度、冲击韧性、密度、矫顽磁力以及表层双相区厚度的影响。结果表明:在渗碳的开始阶段,合金的抗弯强度、冲击韧性以及表面硬度均随渗碳时间的延长而增大;继续延长渗碳时间,合金的力学性能开始下降;合理控制渗碳时间以便得到适当厚度的WC+Co两相区是获得高性能梯度结构硬质合金的关键因素之一;在渗碳过程中,合金的矫顽磁力和密度随渗碳时间的增加而下降,表层WC+Co两相区的厚度随渗碳时间的增加而增加。     

Relationship between gender and holistic representations of health and illness

Steady-state arterial spin tagging MRI approaches were used to quantitate regional cerebral blood flow increases during finger tapping tasks in seven normal subjects. Statistically significant increases in cerebral blood flow were observed in the contralateral primary sensorimotor cortex in all seven subjects and in the supplementary motor area in five subjects. The intrinsic spatial resolution of the cerebral blood flow images was approximately 4 mm. If no spatial filtering was applied, the average increase in cerebral blood flow in the activated primary sensorimotor cortex was 60 +/- 10 cc/100 g/min (91 +/- 32%). If the images were filtered to a spatial resolution of 15 mm, the average increase in cerebral blood flow in the activated primary sensorimotor cortex was 23 +/- 7 cc/100 g/min (42 +/- 15%), in agreement with previously reported 133Xe and PET results.     

The relationship of the changing structure of families and the health of children

The changing family structure impacts on the physical and mental health, emotional state and academic performance of children. Children reared in other than a family with both biological parents have increased difficulties. Pediatric dentists will need to consider these realities in their treatment of an increasing diverse population of children.     

Relationship between QRS score and the extent of coronary artery disease

We studied 92 patients to determine the relationship between the QRS treadmill score (QTS) and extent of coronary artery disease. The results were compared to those of ST segment deviation in a < (+)QRS score > population. A cut off point of < 5 mm was used for mild to moderate risk patients whereas a QTS of < 3 was considered high risk for the patients. 43% of the patients had high risk QTS and 57% mild to moderate QTS. A highly significant correlation was observed between the extent of coronary artery disease and the high risk group of patients, whereas nonsignificant changes were observed in the control group (p < 0.001). Finally, the results indicate that in patients with a (+) QTS score (< 5 mm), coronary artery disease was significant and accordingly extensive during coronary angiography. On the other hand, a (+) QRS score proved to be superior to ST deviation in predicting critical coronary stenoses in the same population (F ratio; 41 vs 24).