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Biomedical subjects

D Engel

Publications and source records attributed to D Engel.

At least 19 recordsLinked to original sources
PubMed1992

Reduction in adherence of Actinomyces viscosus after exposure to low-frequency acoustic energy.

The ability of low-frequency (200 Hz) acoustic energy to reduce the adherence of Actinomyces viscosus T14V to saliva-treated hydroxyapatite (SHA) disks was studied. An acoustic pressure range between 0 and 65 kPa and exposure durations between 0 and 8 min were used to study the levels necessary to significantly alter adherence. The effects of acoustic exposure on both bacteria in liquid and bacteria already adhering to SHA disks were studied. A modified enzyme-linked immunosorbent assay was used to assess bacterial adherence. For bacterial suspensions exposed prior to addition to SHA disks, it was found that reductions in adherence were greater for lower bacterial concentrations. Exposure of bacteria already adhering to SHA disks resulted in a decrease in adherence that was independent of the bacterial concentration and linearly related to the logarithm of the exposure duration. In addition to affecting adherence, acoustic energy also dispersed bacterial aggregates. Our results support the concept that low-frequency sonic energy applied orally may be of therapeutic value in reducing adherence and colonization of teeth by plaque bacteria.

Acoustic Stimulation↗
PubMed1992

Activated lymphocyte subsets in adult periodontitis.

The activation state of T and B lymphocytes in the peripheral blood of periodontitis patients may be a reflection of disease activity. We have utilized 2- and 3-color flow cytometric analyses using a new chromophore, peridinin chlorophyll A protein, and conventional dyes, fluorescein isothiocyanate and phycoerythrin, conjugated to monoclonal antibodies against activated lymphocyte surface markers to measure blood lymphocyte subsets from 18 periodontitis patients and 16 periodontally healthy control subjects. Two-color flow cytometric analysis demonstrated that the frequency of CD4+ and CD5+ T cells, CD20+ B cells, and CD16+ NK (natural killer) cells were increased in periodontitis patients. Of particular interest, CD4+ activated "memory" T cells, CD5+ B cells, and CD56+ NK effector cells were increased significantly in periodontitis patients (p less than 0.05). While the relationship of lymphocyte activation to periodontal disease activity remains unclear, there may be potential for using 2- and 3-color flow cytometry to subcategorize periodontitis patients into high- and moderate-risk groups.

Adult↗
PubMed1992

Opsonic antibody activity against Actinobacillus actinomycetemcomitans in patients with rapidly progressive periodontitis.

Actinobacillus actinomycetemcomitans has been closely associated with early-onset, severe periodontitis, and such patients often have serum immunoglobulin G (IgG) antibodies reactive with antigens of this gram-negative pathogen. We examined the functionality and potential importance of these antibodies. The opsonic activity against A. actinomycetemcomitans of sera from 30 patients with rapidly progressive periodontitis (RPP) and from 28 periodontally normal subjects was tested by using polymorphonuclear leukocyte (PMN) chemiluminescence and bactericidal assays. Peak chemiluminescence values correlated strongly with killing observed in the PMN-dependent bactericidal assay (r = 0.88; P < 0.001). Neither the mean IgG titer nor the mean peak chemiluminescence differed significantly between the two groups. However, when the relationship between chemiluminescence and titer was examined, regression analysis showed that antibodies present in low-titer normal sera were significantly more effective at opsonizing A. actinomycetemcomitans than antibodies present in low-titer RPP patient sera (P = 0.04). Thus, periodontally normal individuals may be better able than RPP patients to clear A. actinomycetemcomitans in early stages of colonization, and anti-A. actinomycetemcomitans antibodies in RPP patients may be relatively ineffective in preventing infection by this organism.

Adult↗
PubMed1992

Serum immunoglobulin G antibody to Porphyromonas gingivalis in rapidly progressive periodontitis: titer, avidity, and subclass distribution.

Porphyromonas gingivalis is a suspected pathogen in rapidly progressive periodontitis (RPP). We have determined the anti-P. gingivalis serum immunoglobulin G (IgG) isotype response and avidity and the subclass titer distributions for 30 RPP patients and 30 age-, sex-, and race-matched healthy subjects by using enzyme-linked immunosorbent assay technology. Patients and control subjects were classified as seropositive if their total IgG response to P. gingivalis was twofold or more than the median response in healthy subjects. The predominant antibody responses for both patients and healthy subjects were IgG2 and IgG3, with a subclass order of IgG2 greater than IgG3 greater than IgG1 greater than IgG4. The avidity of the IgG response was highest for the seropositive healthy subjects and was no different between seronegative and seropositive RPP patients. The subclass antibody responses did not depend on gender, and there were no correlations between titer, avidity, or subclass with disease severity in the RPP patients as measured by pocket depth or bone loss on dental X rays. The seronegative RPP patients exhibited antibody responses that were greater than the responses of seronegative healthy subjects for all four subclasses, while the seropositive RPP patients had higher IgG1 and IgG4 levels than seropositive healthy subjects. These findings are consistent with the hypothesis that both carbohydrate and protein antigens are important in the IgG response to P. gingivalis. The relative predominance of IgG2, a subclass which lacks strong complement fixation and opsonic properties, and the low avidity of patient anti-P. gingivalis IgG antibodies suggest that humoral responsiveness to infection with P. gingivalis may be ineffective in clearing this organism.

Adolescent↗
PubMed1992

[AIDS counseling in social welfare for prostitutes in the rural area].

Prostitute welfare and AIDS counselling are in the hands of one person in the rural area of the Westerland district. This offers the opportunity of continuously preventing this disease and giving guidance and the "human touch" in close care in case of a possible infection, especially in view of the lower number of cases examined and advised compared with the figures in the big cities. An anonymous poll among 41 prostitutes shows that they approve of and are satisfied with the concept of the "G-welfare". It also shows that the prostitutes themselves are hardly aware of the HIV-risk, that their customers only rarely accept condoms and that there are problems in the use and the toleration of condoms. These difficulties are the main aspects of the preventive work, as well as the psycho-social care and the personal relationship to those examining.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Altered lymphocyte populations in sphha/sphha mice with chronic hemolytic anemia.

Lymphocyte kinetics and phenotype were examined in mutant anemic sphha/sphha mice that manifest a lifelong lymphocytosis which accompanies their chronic hemolytic anemia. Anemic mice have significant increases in CD4+, CD8+, and sIgM+ lymphocytes in peripheral blood. Pulse and continuous infusion studies with [3H]TdR suggest that this apparent lymphoid expansion is not due to increased production of lymphocytes in bone marrow or thymus but rather to a redistribution of lymphocytes from the spleen to other peripheral lymphoid tissue sites as well as increased proliferation of T and B lymphocytes in lymph nodes. This murine model could be useful to examine lymphocyte perturbations that may accompany chronic hemolytic anemia in humans.

Anemia, Hemolytic, Congenital↗
PubMed1991

Humoral immune responses to Porphyromonas gingivalis before and following therapy in rapidly progressive periodontitis patients.

We have performed studies aimed at elucidating the nature of the humoral immune response in rapidly progressive periodontitis (RPP). We analyzed the sera of 36 periodontally normal subjects and 36 RPP patients for titers and avidities of IgG antibodies reactive with the antigens of Porphyromonas gingivalis using ELISA, prior to and following treatment. We used whole-cell sonicate, purified lipopolysaccharide (LPS), and total extractable protein as plate antigens. Twelve of the patients had antibody titers at least 2-fold greater than the median of the controls and were designated as seropositive. The remaining 24 patients had titers that did not exceed twice the median titer of the controls and were designated as seronegative. For both patient groups, antibody titers were highest when whole-cell antigen was used, intermediate for LPS, and lowest for the protein fraction. Following treatment, median titer for seropositive patients decreased from pretreatment values of 241.7 to 76.5, while median titer for seronegative patients increased from 39.5 to 80.1. Avidities of pretreatment sera from both patient groups for all 3 antigen preparations were lower than the median avidities of the control sera. Avidity significantly increased following treatment to levels greater than those for control sera in both patient groups. Thus, some young adults with severe periodontitis mount a humoral immune response and produce high levels of serum IgG antibodies reactive with antigens of P. gingivalis, while others do not. The antibodies produced are of relatively low avidity, and may therefore be relatively ineffective biologically. Therapy, which greatly reduces antigen load, appears to stimulate production of higher avidity IgG antibodies in both patient groups; in the seropositive group, low avidity antibodies appear to be replaced by antibodies of higher avidity. Both the purified LPS and protein fractions contain reactive antigen(s), although LPS binds more antibody. Our data are consistent with the idea that many RPP patients do not produce protective levels of biologically functional antibody during the course of their natural infection, but they may be stimulated to do so by treatment.

Adult↗
PubMed1979

The effects of intra-arterially administered histamine on vascular permeability.

The influence of intra-arterially administered histamine on the permeability of the articular barrier (synovial membrane plus vascular endothelium) was studied in cats. The dye penetration from the blood through the barrier was tested by perfusing the two knee joints with saline; the histamine solution was infused through one of the circumflex branches of the femoral artery. The dye content of the two perfusates was measured colorimetrically, the local blood supply of the two knee joints thermo-electrically. In the great majority of experiments it was found that the dye excretion was considerably reduced on the histamine-infused side, in spite of marked improvement of blood supply.

Animals↗
PubMed1979

The gastroauricular phenomenon and related vagus reflexes.

Eight lesser known reflexes were grouped together because of their anatomical and physiological relationship. In all of them a branch of the vagus nerve forms a bridge between a circumscribed area of the skin, mostly the external auditory meatus, and an internal organ, namely the stomach, esophagus, lungs, heart, uterus, and some male and female sex organs. The eight reflexes are: (1) Gastroauricular phenomenon (Gaph) (Engel, 1922) in man; (2) Auricular phenomenon (Malherbe, 1958) in man; (3) Pulmonoauricular phenomenon (Deutsch, 1919) in man; (4) Auriculogenital reflex (Bradford, 1937) in cat; (5) Auriculouterine reflex (Vasiliu, 1932) in women; (6) Oculocardiac reflex (Aschner, 1967) in man; (7) Kalchschmidt's reflex in cattle (1956); and (8) Coughing attack with heartburn (Berlin, 1959) in man. The organs involved are either effector or receptor organs. The six reflexes observed in man are of diagnostic significance. Attention is also drawn to analogous reflexes in which the meningeal branch of the vagus is involved.

Animals↗
PubMed1979

The vaginal influx and its significance in the diagnosis of infections of the urinary tract.

The vaginal influx during miction is a frequent phenomenon. In our clinical study it showed a rate of 54 per cent. The significance of pathomorphological substrates is diminishing with the advancing vesical descensus. The posture during miction has but little influence on the vaginal deviation of the urinary stream. The mid-stream urine is relevantly contaminated in every other girl and, therefore, it may be used only for screening. Indication for an antibacterial therapy is based on catheter or puncture urine.

Adolescent↗
PubMed1979

A cat model for the evaluation of mechanisms of bone resorption: induction of bone loss by simulated immune complexes and inhibition by indomethacin.

When simulated immune complexes (SIC) (heat-aggregated IgG) possessing many of the properties of true antigen-antibody complexes were injected via the root canal into the periapical tissues of cat maxillary cuspids, radiographically and histologically evident bone resorption occurred at these sites within 7 days. Bone loss was accompanied in all cases by inflammation of the surrounding collagenous connective tissues and was characterized by the presence of osteoclasts. Bone resorption, but not the accumulation of inflammatory cells, was blocked by the systemic administration of indomethacin, an inhibitor of prostaglandin synthetase. The most likely explanation is that SIC-activated mechanisms such as the complement cascade, prostaglandin synthesis, and neutrophil degranulation were responsible for the bone loss. The minor inflammation and bone loss that followed the repeated injections of BSA and of monomeric IgG can best be explained as a response to trauma. The data presented establish that the cat maxillary cuspid is a useful model in which to explore the mechanism underlying pathological bone resorption.

Animals↗
PubMed1979

The significance of leucocytosis in the X-irradiated tumour-bed.

(1) Present experiments confirm previous studies (Beck and Engel[1], 1927) according to which a tumour implanted s.c. into an X-irradiated area of mice is inhibited in its growth by 50 to 66% as compared with the implant of the nonirradiated side of the same animal. In the present series the growth inhibition amounted to practically 50%. (2) Exposure of the mouse skin to X-radiation caused a marked hyperleucocytosis within the first 24 hours, with a rapid decrease to normal levels within 4 or 5 days. (3) The inhibitory effect of X-radiation on the tumour growth and the inflammatory response of the skin (leucocyte count) did not run a parallel course except during the first few days after irradiation. The conclusion is drawn that hyperleucocytosis of the tumour bed is not the only cause for the tumour growth inhibition.

Animals↗
PubMed1978

The influence of the sympathetic nervous system on capillary permeability.

1. The influence of the sympathetic nervous system on capillary permeability was studied in cats. The dye penetration from the blood through the synovial membrane was tested by perfusing the two knee joints, one of which was deprived of its sympathetic nerve supply by unilateral lumbosacral sympathectomy. 2. In confirmation of previous experiments, it was found in a great majority of experiments that, in spite of marked vasodilatation, the dye excretion was considerably reduced on the sympathectomised side. 3. A large amount of experimental evidence, supporting directly or indirectly, my views, has been reviewed. 4. A permeability factor under the influence of the sympathetic nervous system has been postulated; its character and mechanism is still unknown. 5. Further unpublished experiments seem to support the view that increased blood supply is associated with decreased vascular permeability.

Animals↗
PubMed1978

Morphological features and functional properties of human fibroblasts exposed to Actinomyces viscosus substances.

Connective tissue fibroblasts undergo cytopathic degenerative changes during certain long-term inflammatory diseases such as rheumatoid arthritis and periodontitis. The failure of inflamed tissues to repair properly may result from functional alterations of fibroblasts within the affected tissues. Numerous previous studies indicate that direct cytotoxicity by bacterial or other substances may be responsible for the cellular alterations observed in vivo. We have tested this hypothesis by exposing cultures of human diploid fibroblasts to homogenates of Actinomyces viscosus (a microorganism associated with periodontitis and capable of causing other chronic inflammatory diseases) and analyzing the effects on cell viability, morphology, and function. The cells bind and subsequently engulf relatively large quantities of the bacterial substances. These substances do not appear to be toxic to fibroblasts as determined by 51Cr release and microcytotoxicity assays, although there is a slight but significant decrease in protein synthesis (P less than 0.01) as measured by the incorporation of [14C]proline. However, collagen production was not altered, and the cytopathic alterations observed in diseased tissues in vivo did not occur in the exposed cells. These findings suggest that A. viscosus substances do not directly cause injury to connective tissue fibroblasts in periodontal disease but may, through cell-surface binding, mark these cells for subsequent immune-mediated damage.

Actinomyces↗
PubMed1978

[Late results following palliative vascular embolization in inoperable kidney tumors. (Preliminary report)].

During 18 months in 15 patients with inoperable renal tumours palliative therapeutic vascular embolisations were carried out with the help of an own catheter technique. In contrast to preoperative embolisation (16 patients) in the inoperable cases a non-absorpable polyvinyl alcohol foam substance ("Ivalon") was used, which leads to a secure permanent vascular occlusion. The haematuria occurring in all patients which many times threateningly increased was removed in all cases. There did not appear any essential complications. However, on account of the formation of a symptomatology of renal infarction a clinical after-treatment is necessary. In 12 patients regulary clinical and paraclinical control examinations during an observation period of on an average 11 months were carried out (minimum 6 months, maximum 18 months). 11 of these patients were still alive at the end of the report and had a tolerable or even improved general condition. In angiographical after-controls of 4 patients, and in one case by autopsy, permanent vascular occlusions with formation of necroses of a large area and partly considerable restriction of the tumour kidneys were found. In these cases the therapeutic embolisation led to a provable damage of the tumorous process. An influence of metastases distant from the primary tumour was not observed.

Embolization, Therapeutic↗