Glucosamine reduces the inhibition of proteoglycan metabolism caused by local anaesthetic solution in human articular cartilage: an in vitro study

Background

We assessed whether local anaesthetics caused inhibition of proteoglycan metabolism in human articular cartilage and whether the addition of Glucosamine sulphate could prevent or allow recovery from this adverse effect on articular cartilage metabolism.

Methods

Cartilage explants obtained from 13 femoral heads from fracture neck of femur patients (average age 80 years, 10 female) were exposed to either 1% Lidocaine, 2% Lidocaine, 0.25% Bupivacaine, 0.5% Bupivacaine, 0.5% Levo-bupivacaine or a control solution (M199 culture medium). Glucosamine-6-Sulphate was added during or 1 h after exposure to 0.5% Bupivacaine to assess its protective and reparative effects. After exposure, the explants were incubated in culture medium containing radio labelled 35-sulphate and uptake was measured after 16 h to give an assessment of proteoglycan metabolism.

Results

The reduction in 35-S uptake compared to control was 65% for 1% Lidocaine (p < 0.001), 79% for 2% Lidocaine (p < 0.001), 61% for 0.25% Bupivacaine (p < 0.001), 85% for 0.5% Bupivacaine (p < 0.001) and 77% for 0.5% Levobupivacaine (p < 0.001). Glucosamine was able to protect the articular cartilage by reducing the inhibition of proteoglycan metabolism of 0.5% Bupivacaine from 85 to 30% (p < 0.001). When added after 0.5% Bupivacaine exposure, Glucosamine allowed some recovery with inhibition of metabolism to 70% (p = 0.004).

Conclusion

Our results showed that all local anaesthetic solutions inhibited proteoglycan metabolism in articular cartilage and the addition of Glucosamine was able to reduce the inhibition of metabolism caused by 0.5% Bupivacaine. Intra-articular injection of local anaesthetics requires careful consideration of risks and benefits.

Absence of germline infection in male mice following intraventricular injection of adenovirus

The possibility of inadvertent exposure of gonadal tissue to gene therapy vectors has raised safety concerns about germline infection. We show here that the receptor for coxsackie B viruses and adenoviruses 2 and 5 (CXADR) is expressed in mouse germ cells, suggesting the possibility that these viruses could infect germ cells. To directly assess the risk of germline infection in vivo, we injected an adenovirus carrying the germ-cell-specific protamine promoter fused to the bacterial lacZ reporter gene into the left ventricular cavity of mice and then monitored expression of the reporter gene in germ cells. To differentiate between infection of stem cells and differentiating spermatogenic cells, we analyzed expression of the reporter cassette at different times after viral delivery. Under all conditions tested, mice did not express the Escherichia coli beta-galactosidase protein in developing spermatids or in mature epididymal spermatozoa. Primary germ cells cultured in vitro were also refractory to adenoviral infection. Our data suggest that the chance of vertical germline transmission and insertional mutagenesis is highly unlikely following intracoronary adenoviral delivery.

Coagulation factor IX: successful surgical experience with a purified factor IX concentrate

The use of plasma-derived coagulation factor concentrates has been marked by the transmission of viral agents. Infusions of factor IX complex concentrates have been additionally complicated by inappropriate thrombosis. Use of these concentrates in the neonate, in those with liver disease, and in surgical patients results in increased risk for this complication. Twenty patients have been infused with a purified coagulation factor IX concentrate for fall-off and recovery studies. A two-compartment model indicated an initial phase half-life of 4.06 +/- 2.86 hr and a beta phase half-life of 20.0 +/- 3.8 hr following the administration of AlphaNine, Coagulation Factor IX (Human). In vivo recovery was 62.7% +/- 13.8%, with an average factor IX coagulant level of 73% +/- 16% at 15 min after the infusion of a mean dose of 45 U/kg. Thirteen previously transfused patients with hemophilia B underwent major orthopedic or general or dental surgery using this purified factor IX. Operative outcomes were excellent in all patients. No excessive bleeding was noted. There was no laboratory or clinical evidence for a disseminated intravascular coagulopathy. The excellent surgical outcomes observed in this multitransfused group with biochemical evidence for active liver disease demonstrates the utility and safety of a purified coagulation factor IX concentrate.

Separation of luminal and abluminal membrane enriched domains from cultured bovine aortic endothelial cells: monoclonal antibodies specific for endothelial cell plasma membranes

Two kinds of membrane (luminal and abluminal membrane domains) fractions have been isolated from bovine aortic endothelial cells by fractionation of whole cell homogenate on discontinuous sucrose density gradients. The luminal membrane domain was enriched 12-16-fold for angiotensin-converting enzyme activity and 8-10-fold in alkaline phosphatase activity. The abluminal membrane domain displayed an enrichment of 8-fold in (Na+ + K+)-ATPase activity. Both of the membrane domains were minimally contaminated with mitochondria, microsomes and Golgi bodies, as assessed by their corresponding marker enzyme activities. 125I-labeling of endothelial cell monolayers by the Enzymo-Bead lactoperoxidase-catalyzed iodination procedure, followed by isolation of membranes, revealed that the radioactivity was predominantly associated with membranes enriched in angiotensin-converting enzyme activity, corresponding to the luminal membrane domain. However, when cells were radioiodinated in suspension culture, radioactivity was found equally associated in both the luminal and abluminal membrane fractions. Electron microscopy of freeze-fractured and sectioned material showed both luminal and abluminal membrane domains to be in the form of vesicles varying in size from 100 to 400 nm in diameter. To characterize the separation of endothelial cell membrane domains, we have attempted to prepare monoclonal antibodies specific for endothelial cells. Several clones were obtained, producing antibodies which bound to endothelial cells of arterial, venous and capillary origin. Two antibodies of these clones, XIVC6 and XVD2, were studied in more detail. In the ELISA assay, these antibodies reacted with bovine vascular endothelial cells, but not with human umbilical cord endothelial cells, nor with bovine corneal endothelial cells, smooth muscle cells or fibroblasts. Both of these antibodies are directed against an antigen of approximately 130 kDa, under reducing and non-reducing conditions, as assayed by the immunoprecipitation method. Western blot analysis of luminal and abluminal membrane fractions revealed that only MAb XVD2 reacted with an antigen, indicating that the antibody XIVC6 is directed against an epitope which is denatured by SDS. Moreover, MAb XVD2 preferentially reacted with the luminal membrane compared to the abluminal membrane domain of the endothelial cell. These monoclonal antibodies do not react with platelet membrane proteins, indicating that this 130 kDa membrane antigen is not common to both endothelial cells and platelets.(ABSTRACT TRUNCATED AT 400 WORDS)

Development of the nematocyte junctional complex in hydra tentacles in relation to cellular recognition and positioning

Formation of the nematocyte-battery cell-mesoglea (NBM) junctional complex of hydra was studied. Normal animals were grafted to nematocyte-free animals and the tentacles of the repopulating host were examined by transmission electron microscopy. Migrating nematocytes extend cytoplasmic processes between battery cell myonemes to contact the mesoglea. Tufts of extracellular filaments radiate from the base of the battery cell adjacent to some of these regions of contact. The fascial desmosome of the NBM complex develops from a lateral fusion of macular desmosomes which often lie near a condensation of extracellular filaments. Microtubules within the intervening battery cell process become oriented perpendicularly to form the apposing half of the desmosomal junction and connect it with the hemidesmosomal portion of the NBM complex. These findings suggest that a migrating nematocyte receives environmental cues associated with the mesoglea-battery cell interface which may serve to direct the nematocyte to its definitive position and induce the subsequent formation of the complete NBM complex.