Surgery (RMH) - Research Publications
Now showing items 1-12 of 705
Constitutive activation of the Src family kinase Hck results in spontaneous pulmonary inflammation and an enhanced innate immune response
(ROCKEFELLER UNIV PRESS, 2002-09-02)
To identify the physiological role of Hck, a functionally redundant member of the Src family of tyrosine kinases expressed in myelomonocytic cells, we generated Hck(F/F) "knock-in" mice which carry a targeted tyrosine (Y) to phenylalanine (F) substitution of the COOH-terminal, negative regulatory Y(499)-residue in the Hck protein. Unlike their Hck(-/-) "loss-of-function" counterparts, Hck(F/F) "gain-of-function" mice spontaneously acquired a lung pathology characterized by extensive eosinophilic and mononuclear cell infiltration within the lung parenchyma, alveolar airspaces, and around blood vessels, as well as marked epithelial mucus metaplasia in conducting airways. Lungs from Hck(F/F) mice showed areas of mild emphysema and pulmonary fibrosis, which together with inflammation resulted in altered lung function and respiratory distress in aging mice. When challenged transnasally with lipopolysaccharide (LPS), Hck(F/F) mice displayed an exaggerated pulmonary innate immune response, characterized by excessive release of matrix metalloproteinases and tumor necrosis factor (TNF)alpha. Similarly, Hck(F/F) mice were highly sensitive to endotoxemia after systemic administration of LPS, and macrophages and neutrophils derived from Hck(F/F) mice exhibited enhanced effector functions in vitro (e.g., nitric oxide and TNFalpha production, chemotaxis, and degranulation). Based on the demonstrated functional association of Hck with leukocyte integrins, we propose that constitutive activation of Hck may mimic adhesion-dependent priming of leukocytes. Thus, our observations collectively suggest an enhanced innate immune response in Hck(F/F) mice thereby skewing innate immunity from a reversible physiological host defense response to one causing irreversible tissue damage.
Lyn-deficient mice develop severe, persistent asthma: Lyn is a critical negative regulator of Th2 immunity
(AMER ASSOC IMMUNOLOGISTS, 2005-08-01)
The etiology of asthma, a chronic inflammatory disorder of the airways, remains obscure, although T cells appear to be central disease mediators. Lyn tyrosine kinase has been implicated as both a facilitator and inhibitor of signaling pathways that play a role in allergic inflammation, although its role in asthma is unclear because Lyn is not expressed in T cells. We show in the present study that Lyn-/- mice develop a severe, persistent inflammatory asthma-like syndrome with lung eosinophilia, mast cell hyperdegranulation, intensified bronchospasm, hyper IgE, and Th2-polarizing dendritic cells. Dendritic cells from Lyn-/- mice have a more immature phenotype, exhibit defective inhibitory signaling pathways, produce less IL-12, and can transfer disease when adoptively transferred into wild-type recipients. Our results show that Lyn regulates the intensity and duration of multiple asthmatic traits and indicate that Lyn is an important negative regulator of Th2 immune responses.
Imbalanced gp130-dependent signaling in macrophages alters macrophage colony-stimulating factor responsiveness via regulation of c-fms expression
(AMER SOC MICROBIOLOGY, 2004-02-01)
The mechanisms by which interleukin-6 (IL-6) family cytokines, which utilize the common receptor signaling subunit gp130, influence monocyte/macrophage development remain unclear. Here we have utilized macrophages devoid of either gp130-dependent STAT1/3 (gp130(Delta STAT/Delta STAT)) or extracellular signal-regulated kinases 1 and 2 (ERK1/2) mitogen-activated protein (MAP) kinase (gp130(Y757F/Y757F)) activation to assess the individual contribution of each pathway to macrophage formation. While the inhibition by IL-6 of macrophage colony-stimulating factor (M-CSF)-induced colony formation observed in gp130(wt/wt) mice was abolished in gp130(Delta STAT/Delta STAT) mice, inhibition of macrophage colony formation was enhanced in gp130(Y757F/Y757F) mice. In gp130(Delta STAT/Delta STAT) bone marrow-derived macrophages (BMMs), both IL-6- and M-CSF-induced ERK1/2 tyrosine phosphorylation was enhanced. By contrast, tyrosine phosphorylation of ERK1/2 in response to M-CSF was reduced in gp130(Y757F/Y757F) BMMs, and the pattern of ERK1/2 activation in gp130 mutant BMMs correlated with their opposing responsiveness to M-CSF-induced proliferation. When compared to the level of expression in gp130(wt/wt) BMMs, c-fms expression was elevated in gp130(Delta STAT/Delta STAT) BMMs but reduced in gp130(Y757F/Y757F) BMMs. Finally, an ERK1/2 inhibitor suppressed M-CSF-induced BMM proliferation, and this result corresponded to a reduction in c-fms expression. Collectively, these results provide a functional and causal correlation between gp130-dependent ERK MAP kinase signaling and c-fms gene activation, a finding that provides a potential mechanism underlying the inhibition of M-CSF-dependent macrophage development by IL-6 family cytokines in mice.
High prostatic fascia release or standard nerve sparing? A viewpoint from the Royal Melbourne Hospital.
(Springer Science and Business Media LLC, 2008-09)
Radical prostatectomy with preservation of the neurovascular bundles (NVB) is a treatment option for localised prostate cancer in selected patients. An interesting debate has developed about the precise technique used to preserve these nerves. The standard technique releases the NVB from the postero-lateral groove between the prostate and rectum. A new technique, dubbed the "veil of Aphrodite" technique, proposes a higher release of the lateral prostatic fascia on the presumption that cavernosal nerves exist in this area. We have reviewed the evidence for the anatomical basis of nerve-sparing radical prostatectomy, particularly with respect to the standard versus the "veil" technique of radical prostatectomy. Microdissections of the NVB in cadaveric specimens have confirmed the course of the cavernosal nerves in the postero-lateral groove between the prostate and rectum. Though studies have also demonstrated nerves higher in the lateral prostatic fascia, these are likely to innervate the prostate rather than the cavernosal tissues. Though excellent potency results have been reported for the "veil" technique from one institution, there is not sufficient anatomical evidence to support this technique over the standard technique of nerve-sparing radical prostatectomy.
Salvage robotic-assisted laparoscopic radical prostatectomy following failed primary high-intensity focussed ultrasound treatment for localised prostate cancer.
(Springer Science and Business Media LLC, 2008-09)
We report the first case of salvage robotic-assisted laparoscopic radical prostatectomy (RALP) following failed primary high-intensity focussed ultrasound (HIFU) for localised carcinoma of the prostate. A 66-year-old male with a presenting prostate-specific antigen (PSA) of 5 ng/ml was diagnosed with T1c Gleason 3 + 4 prostate cancer. He underwent transurethral resection of the prostate and HIFU. His PSA dropped to 2.0 ng/ml and repeat biopsy revealed upgrading of his prostate cancer to Gleason 4 + 3. He was referred to us for a second opinion and, following discussion of his options, he underwent RALP. The total operative time was 159 min. There were no intra- or postoperative complications. He was discharged on postoperative day two and was fully continent 10 days following removal of his catheter. His PSA remained undetectable 6 months postoperatively. Salvage RALP was feasible in this case with good functional and short-term oncological outcomes for the patient.
Wnt Signalling Pathway Parameters for Mammalian Cells
(PUBLIC LIBRARY SCIENCE, 2012-02-21)
Wnt/β-catenin signalling regulates cell fate, survival, proliferation and differentiation at many stages of mammalian development and pathology. Mutations of two key proteins in the pathway, APC and β-catenin, have been implicated in a range of cancers, including colorectal cancer. Activation of Wnt signalling has been associated with the stabilization and nuclear accumulation of β-catenin and consequential up-regulation of β-catenin/TCF gene transcription. In 2003, Lee et al. constructed a computational model of Wnt signalling supported by experimental data from analysis of time-dependent concentration of Wnt signalling proteins in Xenopus egg extracts. Subsequent studies have used the Xenopus quantitative data to infer Wnt pathway dynamics in other systems. As a basis for understanding Wnt signalling in mammalian cells, a confocal live cell imaging measurement technique is developed to measure the cell and nuclear volumes of MDCK, HEK293T cells and 3 human colorectal cancer cell lines and the concentrations of Wnt signalling proteins β-catenin, Axin, APC, GSK3β and E-cadherin. These parameters provide the basis for formulating Wnt signalling models for kidney/intestinal epithelial mammalian cells. There are significant differences in concentrations of key proteins between Xenopus extracts and mammalian whole cell lysates. Higher concentrations of Axin and lower concentrations of APC are present in mammalian cells. Axin concentrations are greater than APC in kidney epithelial cells, whereas in intestinal epithelial cells the APC concentration is higher than Axin. Computational simulations based on Lee's model, with this new data, suggest a need for a recalibration of the model.A quantitative understanding of Wnt signalling in mammalian cells, in particular human colorectal cancers requires a detailed understanding of the concentrations of key protein complexes over time. Simulations of Wnt signalling in mammalian cells can be initiated with the parameters measured in this report.
The impact on cardiac diagnosis and mortality of focused transthoracic echocardiography in hip fracture surgery patients with increased risk of cardiac disease: a retrospective cohort study
Hip fracture surgery is associated with a high rate of mortality and morbidity; heart disease is the leading cause and is often unrecognised and inadequately treated. Pre-operative focused transthoracic echocardiography by anaesthetists frequently influences management, but mortality outcome studies have not been performed to date. Mortality over the 12 months after hip fracture surgery, in 64 patients at risk of cardiac disease who received pre-operative echocardiography, was compared with 66 randomised historical controls who did not receive echocardiography. Mortality was lower in the group that received echocardiography over the 30 days (4.7% vs 15.2%, log rank p=0.047) and 12 months after surgery (17.1% vs 33.3%, log rank p=0.031). Hazard of death was also reduced with pre-operative echocardiography over 12 months after adjustment for known risk factors (hazard ratio 0.41, 95% CI 0.2-0.85, p=0.016). Pre-operative echocardiography was not associated with a delay in surgery. These data support a randomised controlled trial to confirm these findings.