Evidence that the receptor for soluble CD14:LPS complexes may not be the putative signal-transducing molecule associated with membrane-bound CD14.

Membrane-bound CD14 acts as a receptor for lipopolysaccharide (LPS) on monocytes/macrophages and neutrophils. Studies have suggested that the activation of monocytes/macrophages by the binding of LPS to membrane-bound CD14 may require the association of a signal-transducing molecule with membrane-bound CD14. The observation that non-CD14 expressing cells, such as endothelial cells, can nevertheless be activated by a complex of LPS and a soluble form of CD14 (sCD14) suggests that the receptor for this complex may be identical to the signal transducing molecule associated with membrane-bound CD14. The studies described show that two CD14-specific MoAb are able to block the LPS-induced activation of endothelial cells but do not affect the response of monocytes to LPS. This suggests that the interaction of the sCD14:LPS complex with endothelial cells is distinct from the interaction of membrane-bound CD14 with its putative signal-transducing molecule.

Recombinant soluble CD14 prevents mortality in mice treated with endotoxin (lipopolysaccharide).

Endotoxic shock is a life-threatening condition mediated by cytokines released after exposure to bacterial LPS/endotoxin. Activation of monocytes and neutrophils by the binding of LPS to the membrane receptor, CD14, plays a key role in this response. Furthermore, a soluble form of the CD14 receptor enhances the endothelial cell response to LPS. We show here that despite the agonist effects of soluble CD14 on the endothelial cell response to LPS, recombinant soluble CD14 is able to protect mice from LPS-induced lethality. This protection appears to be associated with the inhibition of TNF-alpha release. These results suggest that the soluble CD14 receptor may represent a new form of therapy for endotoxic shock in humans.

Inhibition of lipopolysaccharide and IL-1 but not of TNF-induced activation of human endothelial cells by suramin.

The binding and trans-endothelium migration of inflammatory cells is believed to play a critical role in a variety of inflammatory conditions. This study investigates the ability of the experimental drug suramin to block the activation of HUVEC by endotoxin and by the proinflammatory cytokines IL-1 and TNF. We demonstrate that the inducible expression of several adhesion molecules by LPS and IL-1 beta but not by TNF-alpha is prevented by suramin. In a dose-dependent manner, suramin inhibits the binding of neutrophils and T lymphocytes to LPS and IL-1 beta but not to TNF-alpha-activated HUVEC. The inhibitory effect of the drug on IL-1 beta-induced but not on LPS-induced cell stimulation can be completely reversed by the addition of excess cytokine but not by excess LPS. Because LPS activation of HUVEC is known to depend on serum/plasma-derived soluble CD14, we set out to determine whether suramin inhibition involves interference with the action of the CD14-LPS complex on HUVEC. Indeed, the drug prevents the binding of radioactive LPS in the presence of serum and inhibits LPS-induced cell activation in serum-free medium supplemented with recombinant soluble CD14. The results suggest that suramin interferes with the CD14-dependent activation of HUVEC and that it also may be a useful agent in blocking infectious endotheliopathies in vivo.

Recombinant soluble CD14 inhibits LPS-induced tumor necrosis factor-alpha production by cells in whole blood.

CD14 functions as a cell surface receptor for LPS in the activation of monocytes/macrophages and neutrophils by endotoxin. To assess the utility of soluble forms of the CD14 receptor as a possible therapeutic for endotoxin shock, we have produced recombinant human soluble CD14 using a baculovirus expression system. We find that the recombinant protein is not only expressed on the surface of the insect cells as a glycosyl phosphatidylinositol (GPI)-anchored protein, but is also released into the culture medium as a soluble form that lacks the GPI anchor. Functional analyses of recombinant human soluble CD14 show that it binds specifically to LPS and can inhibit the LPS-induced release of TNF-alpha by macrophages and mononuclear cells as well as by cells in whole human blood when used at concentrations of approximately 70 micrograms/ml. Thus, soluble CD14 may be useful as an adjunct in the treatment of endotoxin shock.

[Colles fracture and instability of wrist joint].

We reviewed 51 cases of colles fracture patients with 3-6 years follow-up and found 20 cases had dorsal carpal subluxation (DCS) in this group. Long term results were analysed and compared between the simple Colles fracture and the Colles fracture with DCS. It was shown that the remote function of the wrist in the simple Colles fracture was much more satisfactory than in that with DCS. That indicated the DCS is a very important factor to the late results of the wrist after Colles fracture. The authors pointed out that the DCS occurs frequently in the severely displaced type caused by high energy force and in the fracture associated with scapholunate dissociation. During the close reduction of the Colles fracture associated with DCS, correction of the palmar angulation and decrease of the angle of palmar tilt should be required, as well as the neutral or light dorsal flexion fixation of the wrist after reduction.

Endotoxin-mediated endothelial cell injury and activation: role of soluble CD14.

Vascular endothelial cell (EC) injury by lipopolysaccharides (LPS) plays a major role in the pathogenesis of gram-negative bacterial sepsis and endotoxic shock. The studies described here were performed to define further the molecular mechanisms involved in the EC responses to LPS. We showed that serum was required for LPS-mediated cytotoxicity for bovine brain microvessel, pulmonary, and aortic ECs and that anti-human CD14 antibodies completely blocked LPS-mediated cytotoxicity for ECs in the presence of human serum. The addition of a recombinant soluble form of human CD14 to serum-free medium restored the LPS-mediated cytotoxicity, whereas the addition of LPS binding protein (LBP), a serum protein that potentiates LPS-induced responses to monocytes, had no effect. A similar dependency on serum or recombinant soluble CD14 (under serum-free conditions) was observed for LPS-induced secretion of interleukin-6 by human umbilical vein ECs. These findings indicate that soluble CD14 is required for LPS-mediated EC responses independently of LPB, suggesting that serum soluble CD14 represents a naturally occurring agonist for EC responses to LPS.

Recombinant soluble CD14 mediates the activation of endothelial cells by lipopolysaccharide.

Recent studies have suggested that soluble CD14 found in serum is involved in the LPS-induced activation of endothelial cells (EC). To more fully investigate the relevance of sCD14 to LPS-induced activation of EC, we have used recombinant soluble CD14 (rsCD14) and have examined, under serum-free conditions, its role in the LPS-induced EC response in the presence of LPS alone as well as in the presence of LPS-binding protein. Our studies show that EC can be activated by high concentrations of LPS in the presence of rsCD14 alone. However, at low concentrations of LPS (5 and 10 ng/ml), the rsCD14-stimulated activation is strongly enhanced by LPS-binding protein. In addition, we show that LPS binds to rsCD14 directly; in the presence of low concentrations of LPS this binding is enhanced by the presence of LPS-binding protein. These results show that while the membrane form of CD14 can function as a receptor, its soluble form can function as a co-ligand with LPS in the EC-LPS response.

Transgenic mice expressing human CD14 are hypersensitive to lipopolysaccharide.

In vitro studies have previously shown that the myelomonocytic differentiation antigen CD14 is a receptor for a complex consisting of lipopolysaccharide (LPS) and LPS-binding protein. To investigate the role of CD14 in vivo and its relationship to induction of LPS-induced endotoxin shock, transgenic mice expressing human CD14 were produced. These mice express human CD14 strongly on the surface of their monocytes, neutrophils, and Thy-1(+) lymphocytes and are hypersensitive to LPS, as evidenced by their increased susceptibility to endotoxin shock. These results document the importance of CD14 in vivo as a primary mediator of this lethal syndrome. Furthermore, these mice provide an important model for testing the therapeutic effects of agents directed specifically against the human, as opposed to the murine, CD14 protein in preventing LPS-induced endotoxin shock.

The role of cruciate ligaments in maintaining knee joint stability.

The role of the cruciate ligaments in maintaining the stability of the knee joint is delineated by experimental studies on 21 fresh adult knee specimens in addition to the analysis of symptoms in 111 cases of cruciate ligament injuries. Cruciate ligaments maintain not only the anteroposterior stability, but also rotational and one-plane medial or lateral stability together with the medial and lateral structures. The anterior cruciate ligament (ACL) plays a part in maintaining anterior one-plane stability and rotational stability of the knee, while the posterior cruciate ligament plays a major part in maintaining both posterior one-plane stability and rotational stability of the knee. An isolated medial (or lateral) ligament (ML) tear can only result in medial or lateral one-plane instability and an increased rotation, but no shift of the axis of rotation occurs. It is not a genuine rotational instability. Both ACL and ML tears are present in one-plane medial, one-plane anterior, and anteromedial rotational instability, but the anterior drawer test or abduction stress test may be negative if the tear of the ACL or ML is partial.

Coverage of wounds in the distal lower leg by advancement of an enlarged medial gastrocnemius skin flap.

Advancement of a medial gastrocnemius flap is a new technique in treating skin defects of the lower third of the lower leg, including that at the anteromedial aspect of the distal portion of the lower leg. Satisfactory results have been obtained in two clinical cases using this technique. In this modified technique, the size of the flap is enlarged, the origin of the medial head of the gastrocnemius is severed so that the island myocutaneous flap may be advanced 8 to 9 cm distally, and good blood supply to the flap is also maintained. In the authors' opinion, this method is a new approach that is simple, easy, safe, and reliable in treating skin defects of the lower leg.