Effects of lidocaine and epinephrine on cutaneous blood flow.

BACKGROUND: Local anaesthetic agents in combination with epinephrine are frequently used in local reconstructive procedures such as skin tumour excision and local flap closure. The purpose of this study was to measure the effect of subdermal injection of lidocaine combined with epinephrine on cutaneous blood flow in the forearm and in the face. METHODS: Thirty injections were performed on the forearm and 40 injections were performed on the face in five healthy volunteers. In both anatomical regions, 0.9% phosphate buffered saline (PBS) was used as a control, and experimental injections included 1% lidocaine either alone or in combination with 1:100,000 epinephrine, and an additional combination of 1% lidocaine with 1:200,000 epinephrine used in the facial experiments. Cutaneous blood flow was measured indirectly using laser Doppler imaging (moorLDI-Mark 2). RESULTS: A statistically significant increase in blood flow was achieved with injection of lidocaine in the forearm compared to saline, whereas a non-statistically significant increase was achieved with saline injection compared to lidocaine in the face. This occurred in the first 5 min in the forearm and 2 min in the face. The addition of 1:100,000 epinephrine to lidocaine resulted in an immediate decrease in cutaneous blood flow which was maximal at 10 min in the forearm and 8 min in the face. This was statistically significant compared to all other injections except for the combination of 1:200,000 epinephrine with lidocaine, injected in the face. CONCLUSIONS: The vascularity of different anatomical areas may account for blood flow differences following injection with saline and lidocaine. Incisions should be delayed for 10 min in the forearm and 8 min in the face following lidocaine+epinephrine injection to allow maximal benefit to take effect. There were no significant differences between 1:100,000 and 1:200,000 epinephrine combined with lidocaine in facial injections his study.

Chondrosarcoma of the anterior mandible. A case report.

Chondrosarcomas of the maxillofacial region are extremely rare tumors, accounting for approximately 1% of chondrosarcomas of the entire body. This case represents the 12th case of mandibular symphyseal chondrosarcoma reported in the literature. It presented as a painful swelling of the alveolus, associated with a mobile mandibular incisor. The patient remains free from recurrence six years after a marginal resection.

High affinity IgG receptor activation of Src family kinases is required for modulation of the Shc-Grb2-Sos complex and the downstream activation of the nicotinamide adenine dinucleotide phosphate (reduced) oxidase.

We used the U937 cell line to examine the modulation of adaptor protein interactions (Shc, Grb2, and Cbl) after high affinity IgG receptor (FcgammaRI) cross-linking, leading to the formation of the Grb2-Sos complex, the activation of Ras, and the regulation of the respiratory burst. Cross-linking of FcgammaRI induced the conversion of GDP-Ras to GTP-Ras reaching a maximum 5 min after stimulation. Concomitant with Ras activation, Sos underwent an electrophoretic mobility shift and the Sos-Grb2 association was increased (6-fold). The Grb2-Sos complex was present only in the membrane fraction and was augmented after FcgammaRI stimulation. Tyrosine-phosphorylated Shc, mainly the p52 isoform, was observed to transiently onload to the membrane Grb2-Sos complex on FcgammaRI stimulation. Cross-linking of FcgammaRI induces the tyrosine phosphorylation of Cbl, which forms a complex with Grb2 and Shc via the Cbl C terminus. Kinetic experiments confirm that Cbl-Grb2 is relatively stable, whereas Grb2-Sos, Grb2-Shc, and Cbl-Shc interactions are highly inducible. The Src family tyrosine kinase inhibitor, PP1, was shown to completely inhibit Shc tyrosine phosphorylation, the Shc-Grb2 interaction, and the FcgammaR-induced respiratory burst. Our results provide the first evidence that the upstream activation of Src kinases is required for the modulation of the Shc-Grb2 interaction and the myeloid NADPH oxidase response.

Role of Src in the modulation of multiple adaptor proteins in FcalphaRI oxidant signaling.

Cross-linking of Fc receptors for IgA, FcalphaR (CD89), on monocytes/macrophages is known to enhance phagocytic activity and generation of oxygen free radicals. We provide evidence here that the FcalphaR signals through the gamma subunit of FcepsilonRI in U937 cells differentiated with interferon gamma (IFNgamma). Our results provide the first evidence that FcalphaR-mediated signals modulate a multimolecular adaptor protein complex containing Grb2, Shc, SHIP, CrkL, Cbl, and SLP-76. Cross-linking of FcalphaRI using anti-FcalphaRI induces the phosphorylation of the gamma subunit as detected by mobility retardation on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Stimulation of FcalphaRI induced the tyrosine phosphorylation of Shc and increased the association of Grb2 with Shc and CrkL. Grb2 associates constitutively with Sos, and the latter undergoes mobility shift upon FcalphaRI stimulation. The complex adapter proteins, Cbl and SLP-76, are physically associated in myeloid cells and both proteins undergo tyrosine phosphorylation upon FcalphaR stimulation. These data indicate that the stimulation of FcalphaR results in the modulation of adaptor complexes containing tyrosine-phosphorylated Cbl, Shc, SHIP, Grb2, and Crkl. Experiments performed with the Src kinase inhibitor, PP1, provide the first evidence that Src kinase activation is required for FcalphaRI-induced production of superoxide anions and provide insight into the mechanism for FcalphaR-mediated activation of downstream oxidant signaling in myeloid cells.

Cbl functions downstream of Src kinases in Fc gamma RI signaling in primary human macrophages.

Cbl is a cytosolic protein that is rapidly tyrosine phosphorylated in response to Fc receptor activation and binds to the adaptor proteins Grb2, CrkL, and Nck. A few reports describe Cbl interactions in primary human hematopoietic cells. We show evidence that Cbl participates in signaling initiated by Fc gammaRI receptor cross-linking in human primary macrophages, and functions downstream of Src family kinases in this pathway. Fc gammaRI stimulation in human macrophages was associated with rapid and transient tyrosine phosphorylation of the Cbl adaptor protein. Immunoprecipitated Cbl was complexed with several tyrosine phosphorylated proteins, the most prominent of which was a 38-kDa band identified as the CrkL adaptor protein. CrkL associated with tyrosine-phosphorylated Cbl and itself became tyrosine phosphorylated after Fc gammaRI cross-linking. SLP-76, a recently cloned Grb2-associated protein, was strongly tyrosine phosphorylated after Fc gammaRI stimulation and was associated with both Cbl and Grb2. Grb2 and Cbl binding to SLP-76 were inducible after Fc gammaRI stimulation of the macrophages. Nck was inducibly bound to Cbl after Fc gammaRI stimulation, whereas Grb2 was constitutively associated with it. Shc was also inducibly tyrosine phosphorylated and bound to Grb2 after Fc gammaRI stimulation of the macrophages. PP1, a specific inhibitor of Src kinases, inhibited the Fc gammaRI-induced respiratory burst, as well as the tyrosine phosphorylation of Cbl and its inducible association with CrkL. These results suggest a fundamental role for the tyrosine phosphorylation of Cbl, CrkL, SLP-76, and Shc and the association of Cbl with CrkL, SLP-76, and Nck in Fc gammaRI signaling in human macrophages. Experiments performed with PP1, the specific Src kinase inhibitor, demonstrate the first evidence that Cbl and the Cbl-Crkl interaction are downstream targets for myeloid Src kinases required for the activation of myeloid NADPH oxidase activity.

Characterization of Cbl-Nck and Nck-Pak1 interactions in myeloid FcgammaRII signaling.

Fc receptors modulate inflammatory processes, including phagocytosis, serotonin and histamine release, superoxide production, and secretion of cytokines. Aggregation of FcgammaRIIa, the low-affinity receptor for monomeric IgG, activates nonreceptor protein tyrosine kinases such as Lyn, Hck, and Syk, potentially driving the phosphorylation of the downstream adaptor proteins, including Cbl and/or Nck. Previous work from our laboratory using interferon-gamma-differentiated U937 (U937IF) myeloid cells investigated mechanisms which regulate Fcgamma receptor-induced assembly of adaptor complexes. Herein we report that FcgammaRII receptor signaling in U937IF and HEL cells involves Cbl and Nck, suggesting that Cbl-Nck interactions may link FcgammaRII to downstream activation of Pak kinase. FcgammaRII crosslinking induced the phosphorylation of Cbl and Nck on tyrosine. The alphaCbl immunoprecipitations revealed constitutive binding of Nck and Grb2 to Cbl and FcgammaRII-inducible binding of CrkL to Cbl. The interactions of Cbl with Nck and CrkL were phosphorylation dependent since dephosphorylation of cellular proteins with potato acid phosphatase abrogated binding. GST-Nck fusion protein pulldown experiments show that Cbl and Pak1 bind to the second SH3 domain of Nck. A specific Src inhibitor, PP1, was shown to completely abrogate the FcgammaR-induced superoxide response, correlating with a decrease in Cbl and Nck tyrosine phosphorylation. Our results provide the first evidence that Src is required for FcgammaR activation of the respiratory burst in myeloid cells and suggest that Cbl-Nck, Cbl-Pak1, and Nck-Pak1 interactions may regulate this response.