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Biomedical subjects

R Brons

Publications and source records attributed to R Brons.

At least 19 recordsLinked to original sources
PubMed1997

Locus coeruleus activation by colon distention: role of corticotropin-releasing factor and excitatory amino acids.

The present study was designed to elucidate the neurotransmitters involved in activation of the noradrenergic nucleus, locus coeruleus, by distention of the distal colon. Locus coeruleus spontaneous discharge rate was recorded from halothane-anesthetized rats before, during and after distention of the colon produced by inflation of a balloon catheter with varying volumes of water. Locus coeruleus activation by colon distention was volume-dependent and reversible. Activation of cortical electroencephalographic activity was temporally correlated with locus coeruleus activation during colon distention and prolonged distention (greater than 2 min) resulted in tachyphalaxis to both locus coeruleus and cortical electroencephalographic activation. The corticotropin-releasing factor antagonist, DPheCRF(12-41), administered intracerebroventricularly (3 microg) or microinfused into the locus coeruleus (10 ng) significantly attenuated locus coeruleus activation produced by lower, but not higher magnitudes of colon distention, implicating corticotropin-releasing factor afferents to the locus coeruleus in this response. Consistent with this, prior exposure to 30 min of footshock stress, which desensitizes locus coeruleus neurons to corticotropin-releasing factor, produced a similar attenuation of locus coeruleus activation by low, but not high magnitudes of distention. Kynurenic acid, administered intracerebroventricularly (5 micromol), significantly antagonized locus coeruleus activation by all magnitudes of colon distention. However, this excitatory amino acid antagonist was ineffective when administered directly into the locus coeruleus (0.3 nmol). Together, these findings suggest that low magnitudes of colon distention activate the locus coeruleus-noradrenergic system via corticotropin-releasing factor release within the locus coeruleus and that excitatory amino acid neurotransmission at a site distal to the locus coeruleus is necessary for this response. Activation of the locus coeruleus-noradrenergic system during colon distention may serve as a cognitive limb of the peripheral parasympathetic response. This activation may also play a role in disorders characterized by comorbidity of colonic and psychiatric symptoms, such as irritable bowel syndrome.

Animals↗
PubMed1997

[Harmony of the facial profile. Part IV. Sagittal rules].

Different inclines characterize the respective parts of the profile. These inclines are identified by the values of the angles created by the individual reference line and the lines representing the inclines. It is shown how these inclines should relate to achieve individual formal perfection of the profile.

Cephalometry↗
PubMed1996

[Harmony of the facial profile. Part III. Vertical rules].

Rules for profile harmony in the vertical direction reflect the acceptable relations between the heights of the different facial parts. The relation between the maxillary and nasal heights determines the acceptable range for the mandibular height.

Cephalometry↗
PubMed1996

[Harmony of the facial profile. Part I. Introduction and concept definition].

The terms beauty, attractiveness and harmony can be brought together under the notion of esthetics. Harmony is the only notion to provide us with the possibility of formulating objective and generally applicable criteria for an acceptable facial profile. The prerequisites for these criteria are outlined.

Cephalometry↗
PubMed1996

[Harmony of the facial profile. Part II. The analysis].

Rules for harmony of the facial profile reflect the individual perfection of the whole profile. A system of coordinates can be obtained in the same manner in every individual, reflecting the individual form. These coordinates provide valid rules for individual application.

Cephalometry↗
PubMed1992

The supportive effects of IL-7 on eosinophil progenitors from human bone marrow cells can be blocked by anti-IL-5.

Human rIL-7 was studied for its effects on myeloid and erythroid progenitors from human bone marrow cells. IL-7 did not support the granulocytic/monocytic or erythroid lineage but exclusively stimulated eosinophil colony formation (CFU-Eo) (4 +/- 3 vs 48 +/- 17 CFU-Eo/10(5) nonadherent fraction-non-T cell (NAF-NT) cells). This supportive effect was not mediated by T cells or monocytes because similar results were obtained with or without T cell or adherent depleted cell fractions. In addition, it was shown that CD34+ sorted cells could be stimulated by IL-7 (0 vs 15 +/- 9 CFU-Eo/3 x 10(3) CD34+ cells) Furthermore studies with IL-3 or granulocyte-macrophage CSF (GM-CSF) demonstrated an additive effect on the IL-7 supported colony formation. Finally, experiments were performed with anti-IL-3, anti-GM-CSF, anti-IL-1, and anti-IL-5 to exclude the possibility that IL-7 indirectly stimulated the eosinophil progenitor cell. Anti-GM-CSF, anti-IL-1, or anti-IL-3 did not influence the supportive effects of IL-7. However, anti-IL-5 did abolish the effects of IL-7 on the eosinophil colony formation (69 +/- 15 vs 3 +/- 2 CFU-Eo/10(5) NAF-NT, n = 3). Similar results were obtained with CD34+ sorted cells. Moreover, IL-5 mRNA expression could be demonstrated in IL-7-stimulated NAF-NT cells. These data suggest that the supportive effects of IL-7 on eosinophil precursors are mediated by the endogenous release of IL-5.

Antigens, CD↗
PubMed1991

In vitro evaluation of a high-efficiency leukocyte adherence filter.

In view of the currently available data, prevention of alloimmunization requires filters with higher efficiency to achieve a reduction in the number of leukocytes below 10 million per transfusion. Two versions (Pall PL-100 and PL-50) of the new generation leukocyte-depletion filters were studied. Single donor (SDPC)- and pooled multiple donor (MDPC) platelets were run in parallel. At a flow rate of 10 ml/min, the PL-100 filter was shown to effectively reduce the number of residual leukocytes to far below the critical immunogenic threshold of 10 million in all SDPC units and in 77% of MDPC units. Apheresis platelets appear not only to be better depleted than pooled multiple donor platelets, but also to have a better post-filtration platelet recovery (96% versus 84%). The efficiency of the smaller version of the filter (Pall-50) was higher than that of the Pall-100 filter for both single and pooled multiple donor platelet concentrates (PC). Leukocytes were absent in more than 92% of units in both types of concentrates. The maximal number of detected leukocytes was 2.2 million in a pool of 6 units. The outcome of filtration of 5-day-old pooled platelets was less favorable than filtration of 1- or 2-day-old pooled platelets, indicating that filtration soon after preparation is preferred to filtration after storage. Post-filtration platelet integrity, activation state, function, and morphology were all well preserved in both single and multiple PCs.

Blood Component Removal↗
PubMed1990

[Glass ionomer cement used as a retrograde filling material after apicoectomy: a review].

When an apicoectomy is performed, using retrograde sealing with amalgam, the healing of the periapical area is not always perfect. In a number of cases the cause of this imperfect healing may be due to the improper sealing ability and the moderate tissue compatibility of amalgam. A literature study has been carried out, based on the assumption that glass ionomer cement will provide a better sealing and will cause less tissue reaction. It appeared that, at least in theory, glass ionomer cement is to be preferred to amalgam when it comes to apical sealing properties and tissue reaction. In terms of usability, resorption, hardness and costs no significant differences were found. The conclusion is drawn that glass ionomer cement is an equal or perhaps even better alternative for retrograde amalgam.

Apicoectomy↗
PubMed1987

A comparative study of myocardial infarct detection using Tc99m pyrophosphate and In111 DTPA antimyosin (R11D10 Fab).

A crossover study to examine the potential of In111 antimyosin Fab fragment to detect fresh myocardial infarcts in comparison with Tc99m pyrophosphate is reported. In 27 cases indium antimyosin correctly diagnosed 19 patients with infarcts and 4 true negatives. There were also 2 false positive and 2 false negative scintigrams. Tc99m pyrophosphate detected 21 infarcts and 6 true negatives correctly.

Diphosphates↗
PubMed1977

Visor osteotomy and vestibuloplasty--a one-stage procedure. A preliminary report.

The visor osteotomy as described by HARLE gives a considerable increase of the absolute height of the atrophic mandible, between the mental foramina. After 6 weeks a total vestibuloplasty with mucosal grafting (and a lowering of the floor of the mouth) is performed. A method is described in which the visor osteotomy and the vestibuloplasty are performed in one stage.

Atrophy↗
PubMed1977

Treatment of mandibular fractures by means of stable internal wire fixation.

Treatment according to the principles of stable internal fixation offers great advantages for fractures of the mandibular body. Most authors believe that a stable internal fixation can be achieved only by means of bone plating or screw fixation. At Groningen a wire connection was designed by BRONS which could be considered to be stable. The application of this stable internal wire fixation and the results of treatment in 272 fractures of the mandibular body between 1967 and 1976 are discussed.

Fracture Fixation, Internal↗
PubMed1977

Operative treatment of arthrosis deformans of the temporomandibular joint: a preliminary report.

If patients with arthrosis deformans of the temporomandibular joint are treated without success by conservative means, operative therapy may be indicated. The type of operation depends on the complaints: a)resection of the auriculotemporal nerve and superficial temporal artery; or b) the same operation in combination with condylar shaving. Twenty-four joints in 14 patients underwent a denervation. Thirty joints in 19 patients were also shaved. The results were very satisfactory.

Arthritis, Rheumatoid↗