Biomedical subjects
Publications and source records attributed to F Koch.
Skill mix changes can have a severe impact on patient outcomes. In recent years, changes in staffing patterns have been necessitated by an effort to reduce the cost of health care. The increased use of Unlicensed Assistive Personnel has raised the question of what is a safe-cost-effective skill mix.
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Immature dendritic cells (DC), such as freshly isolated Langerhans cells (LC), are excellent at processing native protein Ag. During short term culture they shut off MHC class II synthesis and down-regulate their processing capacity. They retain, however, the MHC/peptide complexes, up-regulate adhesion and costimulatory molecules, and acquire the ability to sensitize T cells. Two reports describing substantial processing activity in populations of mature DC prompted us to undertake an extensive comparative study of the Ag-processing capacities of immature vs mature DC. We used a panel of 17 peptide-specific T cell hybridomas restricted by six different MHC class II molecules: I-Ab, I-A(d), I-E(d), hybrid I-A beta dE alpha, I-Ak, and I-Ek. Side by side comparisons revealed in all cases that freshly isolated LC were superior to cultured mature LC in their ability to process native proteins. With some hybridomas, however, we found a considerable degree of processing by populations of cultured LC at high doses of Ag or Ag-presenting cells. This activity, however, did not correlate with the MHC haplotype. Direct comparison over wide ranges of DC doses or Ag doses showed that it was always less than that of corresponding fresh immature LC. Immunoperoxidase staining of cytospins and flow cytometry with mAb In1 disclosed a small (20% maximum) subset of cultured LC expressing the MHC class II-associated invariant chain, indicating ongoing biosynthesis of this molecule and, thus, incomplete maturation of these LC. Therefore, the residual processing activity observed in populations of mature DC may be explained by small subpopulations of incompletely matured DC.
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Perioperative services team members at Presbyterian Hospital of Dallas employed a methodical redesign process to redefine team members' relationships and revise roles to be patient focused. One outcome of this redesign process was the creation of multiskilled worker (ie, unlicensed assistive personnel) roles within self-managed perioperative specialty teams. An initial pilot project using the multiskilled workers in the neurosurgical specialty service resulted in increased physician and perioperative nurse collaboration and efficiency.
PURPOSE: To free both of the surgeon's hands for bimanual work in the vitreous cavity, Koch and coworkers developed the multiport illumination system, which, however, requires enlarged sclerotomies. PATIENTS AND METHODS: To evaluate the safety of the multiport illumination system we analyzed the first postoperative year of those 104 vitrectomies, that were performed using this system between January and December 1991. It was used only for patients suffering from advanced vitreoretinal changes that most likely require bimanual surgery. RESULTS: No specific intraoperative or postoperative complications were encountered that might possibly have been caused by the multiport illumination system. Postoperative fibrinous reactions were noted in the vitreous cavity of 7 patients, and in the anterior chamber of 15 patients. Rebleeding was observed in a total of 17 patients. CONCLUSION: When these complications were compared to data from other retrospective studies of vitrectomy and its complications, the multiport illumination, system was found to be as safe as conventional devices.
BACKGROUND: Severe complications such as a traumatic wound dehiscence have been described very rarely after radial keratotomy. The following case demonstrates for the first time that wound healing is not completed even 31/2 years postoperatively and that therefore an ocular blunt trauma may still cause a dehiscence of the radial incisions. CASE REPORT: A 22-year-old patient presented in July 1993 to our emergency unit because of a corneal perforation in his right eye after a blunt trauma. His past medical history was significant for radial keratotomy surgery performed in January 1990 to correct a bilateral low-degree myopia (OD = -3.25 D; OS = -3.75 D). At surgery a horizontal rupture running through the entire cornea and including the two radial keratotomies at the 3 and 9 o'clock position was evident. The whole iris and lens were missing. The retina was completely detached. The corneal laceration was sutured. Twelve days later the retina was reattached with an encircling band, vitrectomy, endolaser and cryocoagulation, as well as silicone oil fill. Finally, a penetrating keratoplasty was performed 6 months after the accident. Thereafter, visual acuity improved to 0.1. The histologic examination of the corneal button showed that the wound healing of the incisions that had remained intact was not completed yet. Epithelial plugs of various size were still filling the somewhat dehiscent wound margins. Fibroblastic activity was detected in the surrounding stroma. CONCLUSION: Even several years after surgery, blunt traumas represent a definite risk for eyes undergoing radial keratotomy.
Two men with recent history of lightining strike were referred to our hospital. Both patients complained of metamorphosia in one eye and reduced visual acuity. Funduscopy revealed target-like alterations at the fovea. Fluorescein angiography showed window defects of the central retinal pigment epithelium in both patients. One patient developed an anterior subcapsular cataract. If the eye is part of the current-circuit, the melanin granules of the iris, pigment epithelium, and choroid might act as a resistor. The resulting accumulation of heat may lead to damage of the surrounding tissues.
PURPOSE: To evaluate whether oxidative tissue damage and inflammatory reactions occur in epiretinal membranes of eyes suffering from proliferative diabetic retinopathy (PDR), proliferative vitreoretinopathy (PVR), and macular pucker (MP). METHODS: Epiretinal membranes were removed during surgery and frozen at -80 degrees C (PDR, n = 26; PVR, n = 24; MP, n = 15), and oxidative tissue damage and inflammatory activity (MPO) of the membrane tissue were determined. The values are expressed as means of thiobarbituric acid-reactive substances (TBARS, nmol/mg) and MPO (units/mg). RESULTS: Both TBARS and MPO activity were significantly elevated (P < 0.05) in membranes of eyes suffering from PVR and PDR compared to MP. The myeloperoxidase activity in PDR membranes was significantly increased (P < 0.05) compared to PVR. CONCLUSIONS: Inflammatory cells and oxidative metabolites lead to oxidative reactions in PDR and PVR. The proliferation of membrane tissue may be enhanced through products of the lipoxygenase pathway, which is active in inflammatory cells and leads to oxidative tissue damage. Chemoattraction of leukocytes by oxidative metabolites renders the process self-progagating. Since patients suffering from MP have an intact vitreous body with an intact antioxidative system, this reaction occurs to a lesser degree, resulting in less membrane-growth activity. The cell-growth-enhancing properties of inflammatory cells should be further investigated in PDR and PVR with regard to new therapeutic interventions.
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Dendritic cells form a system of antigen presenting cells that are specialized to stimulate T lymphocytes, including quiescent T cells. The lineage of dendritic cells is not fully characterized, although prior studies have shown that growth and differentiation are controlled by cytokines, particularly granulocyte/macrophage colony-stimulating factor (GM-CSF). To further elucidate the nature and control of the dendritic cell lineage, we have studied the expression of specific cytokine receptors. Sufficient numbers of dendritic cells were purified from spleen and skin to do quantitative binding studies with radiolabeled M-CSF, GM-CSF, and interleukin 1 (IL-1). To verify the nonlymphoid nature of dendritic cells, we made an initial search for rearrangements in T cell receptor and immunoglobulin genes and none were found. M-CSF binding sites, a property of mononuclear phagocytes, also were absent. In contrast, GM-CSF receptors were abundant on mature dendritic cells, with approximately 3,000 binding sites/cell with a single Kd of 500-1,000 pM. Substantial numbers of high affinity (< 100 pM) IL-1 binding sites were identified as well; cultured epidermal dendritic cells (i.e., epidermal Langerhans cells) had 500/cell and spleen dendritic cells approximately 70/cell. Cross-linking approaches showed the 80-kD species that is expected of high-affinity type 1 IL-1 receptor. Anti-type 1 IL-1 receptor (R) mAbs also visualized these receptors by flow cytometry on freshly isolated epidermal dendritic cells. These results provide new evidence that dendritic cells represent a differentiation pathway distinct from lymphocytes and monocytes. Together with recent findings on the effects of IL-1 and GM-CSF on epidermal dendritic cells in situ (see Results and Discussion), the data lead to a proposal whereby IL-1 signals IL-1R to upregulate GM-CSF receptors and thereby, the observed responsiveness of dendritic cells to GM-CSF for growth, viability, and function.
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