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Biomedical subjects

Michael A Zimmerman

Publications and source records attributed to Michael A Zimmerman.

At least 19 recordsLinked to original sources
PubMed2006

Budd-Chiari syndrome.

Budd-Chiari syndrome is a spectrum of disease states, including anatomic abnormalities and hypercoagulable disorders, resulting in hepatic venous outflow occlusion. Clinical manifestations observed in the majority of patients include hepatomegaly, right upper quadrant pain, and abdominal ascites. This article outlines the approach to clinical diagnosis and supportive medical therapy in patients who have BCS and reviews the clinical data supporting surgical shunting and liver transplantation as viable treatment options in this patient population.

Budd-Chiari Syndrome↗
PubMed2006

Effect of nonviral factors on hepatitis C recurrence after liver transplantation.

OBJECTIVE: Hepatitis C (HCV) is now the most common indication for orthotopic liver transplantation (OLT). While graft reinfection remains universal, progression to graft cirrhosis is highly variable. This study examined donor, recipient, and operative variables to identify factors that affect recurrence of HCV post-OLT to facilitate graft-recipient matching. METHODS: Retrospective review of 307 patients who underwent OLT for HCV over a 10-year period at our center. Recurrence of HCV was identified by the presence of biochemical graft dysfunction and concurrent liver biopsy showing diagnostic pathologic features. Time to recurrence was the endpoint for statistical analysis. Five donor, 6 recipient, and 2 operative variables that may affect recurrence were analyzed by univariate comparison and Cox proportional hazard regression models. RESULTS: Recurrence-free survival in the 307 study patients was 69% and 34% at 1 and 5 years, respectively. Four predictive variables related to either donor or recipient characteristics were identified. Advanced donor age, prolonged donor hospitalization, increasing recipient age, and elevated recipient MELD scores were found to increase the relative risk of HCV recurrence. Examination of HLA disparity between donors and recipients demonstrated no correlation between class I or class II mismatches and recurrence-free survival. CONCLUSIONS: We have identified donor and recipient characteristics that significantly predict hepatitis C recurrence following liver transplantation. These factors are identifiable before transplant and, if considered when matching donors to HCV recipients, may decrease the incidence of HCV recurrence after OLT. A change in the current national liver allocation system would be needed to realize the full value of this benefit.

Adult↗
PubMed2005

Fulminant hepatic failure from primary hepatic lymphoma: successful treatment with orthotopic liver transplantation and chemotherapy.

Systemic lymphomas may involve the liver but rarely cause fulminant hepatic failure (FHF). Acute liver failure from primary hepatic lymphoma (PHL) is even less common with most patients succumbing to the sequelae of FHF before the correct diagnosis is made. We report a patient who underwent successful orthotopic liver transplant (OLT) and chemotherapy for FHF secondary to PHL. This previously-well male developed profound coagulopathy and encephalopathy 6 weeks after the onset of jaundice and fatigue. Workup failed to reveal the underlying cause of his liver failure and the patient soon required urgent OLT. Pathologic evaluation of his explanted liver revealed a malignant T-cell rich, large B-cell non-Hodgkin's lymphoma with widespread hepatocellular necrosis. The patient made an excellent clinical recovery and is undergoing CHOP-Rituxan chemotherapy. This scenario demonstrates that lymphoma should be considered in the differential diagnosis of FHF without clear etiology because of the potential for intervention with transplant and chemotherapy.

Combined Modality Therapy↗
PubMed2005

When shouldn't we retransplant?

1. In the setting of early graft failure after primary transplantation, orthotopic liver retransplantation (re-OLT) should be undertaken within the first 7 days, but it should be discouraged within 8-30 days, since re-OLT within this intermediate frame is associated with the worst results. 2. Late retransplantation should be cautioned in severely ill patients who exhibit Model for End-Stage Liver Disease (MELD) scores >25, require mechanical ventilation, have advanced renal insufficiency, and in advanced-age recipients. 3. Re-OLT should not be undertaken with extended and older donors particularly when retransplantation for recurrent disease is considered. 4. Prognostic models that take into account the severity of disease and the effect of the organ to be transplanted should be developed to better predict outcomes after re-OLT. 5. Accurate definitions of acceptable outcomes after retransplantation and "futile re-OLT" are desperately needed.

Graft Rejection↗
PubMed2004

Interleukin-10 attenuates the response to vascular injury.

BACKGROUND: The inflammatory response to vascular injury is characterized by expression of cytokines, growth factors, and chemokines that conspire to promote vessel remodeling and intimal hyperplasia (IH). Interleukin-10 (IL-10) is a multifunctional cytokine that has several anti-inflammatory properties in vitro. Few studies have evaluated the effects of IL-10 in experimental atherosclerosis. The purpose of the present study was to determine the influence of IL-10 on vascular inflammation and IH following mechanical injury. METHODS: Wire carotid injury was performed in wild-type (WT) mice with and without IL-10 treatment. Immunohistochemistry, PCR, and ELISA assays were used to examine vessel production of basic fibroblast growth factor (bFGF), monocyte chemotactic protein-1 (MCP-1), and nuclear factor kappa B (NFkappaB). Vessels were morphometrically analyzed for IH. RESULTS: Carotid injury induced early expression of MCP-1 and bFGF that was abrogated in mice treated with IL-10. Similarly, injury-induced expression of NFkappaB message and protein was attenuated in mice receiving exogenous IL-10. Compared to untreated mice, IL-10 markedly decreased levels of IH. Interestingly, carotid injury in IL-10-deficient mice resulted in an augmented IH response compared to injured WT mice. CONCLUSIONS: In an in vivo model of direct vascular injury, IL-10 decreased expression of the pro-inflammatory transcription factor, NFkappaB, and the mitogenic chemokine and growth factor, MCP-1 and bFGF, respectively. These observations were associated with IL-10-induced attenuation of IH. Furthermore, endogenous IL-10 appeared to suppress the injury response. In conclusion, exogenously delivered IL-10 may represent a clinically relevant anti-inflammatory strategy for post-injury intimal hyperplasia.

Animals↗
PubMed2003

Relative contribution of the TNF-alpha receptors to murine intimal hyperplasia.

Tumor necrosis factor-alpha (TNF-alpha) is an important mediator in the inflammatory response to vascular injury. The present study sought to determine the relative contribution of each TNF-alpha receptor subtype (p55 and p75) to intimal hyperplasia (IH) and characterize the mechanisms of transcriptional regulation after vascular injury. A murine model of wire carotid arterial injury was employed to induce IH in wild-type (WT), p55-deficient (p55-/-), and p75-deficient (p75-/-) mice. Compared with injured WT and p75-/- animals, p55-/- mice demonstrated a twofold reduction in IH. Additionally, p55-/- mice demonstrated a decrease in expression of nuclear factor-kappaB mRNA and protein. These observations suggest an important role for the p55 receptor in IH after mechanical endoluminal injury. Suppression of the transcriptional activator nuclear factor-kappaB may provide a mechanism by which p55-mediated IH is attenuated.

Animals↗
PubMed2003

Diagnostic implications of C-reactive protein.

An elevated level of C-reactive protein (CRP), an acute phase protein, is one of many downstream indicators of inflammation. Physiologically, CRP enhances cell-mediated immunity by promoting phagocytosis, accelerating chemotaxis, and activating platelets. The purposes of this article are (1) to review the clinical data implicating serum CRP level as a systemic marker of focal inflammation and (2) to explore serum CRP level as a reflection of the inflammatory component of atherogenesis. Our findings indicate that CRP levels serve as an early marker of the magnitude of inflammation in events as dissimilar as appendicitis and myocardial infarction. The level of circulating CRP correlates with endovascular disease and may serve to identify otherwise asymptomatic patients at sufficient cardiovascular risk to warrant aggressive therapy. Determining whether CRP has a direct pathologic role in the vascular wall itself may have the most clinical relevance.

Arteriosclerosis↗
PubMed2003

Atherogenic effects of Chlamydia pneumoniae: refuting the innocent bystander hypothesis.

OBJECTIVE: Serologic evidence of Chlamydia pneumoniae infection and atherosclerosis was first demonstrated in patients with ischemic heart disease in 1988. Subsequently, the organism has been detected in several cardiovascular lesions. Outside of observational reports, few studies mechanistically link vascular infection with C. pneumoniae and atherogenesis. To better define its pathophysiologic role, we examined the influence of C. pneumoniae infection of human vascular smooth muscle cells on vascular smooth muscle cell proliferation, cell-cycle protein expression, and inflammatory cytokine release. METHODS: Human aortic vascular smooth muscle cells were inoculated with C. pneumoniae in culture. Proliferation was assessed by mitochondrial activity, direct cell counting, and immunohistochemical staining for proliferating cell nuclear antigen. Electromobility gel shift assays probed for the antiproliferative cell-cycle protein p53. Supernatants were assayed for the mitogens interleukin-6 and interleukin-8 by enzyme-linked immunosorbent assay. RESULTS: After C. pneumoniae inoculation, vascular smooth muscle cell proliferation increased 2-fold by mitochondrial activity and more than 3-fold by cell numbers. C. pneumoniae infection promoted a 3-fold increase in proliferating cell nuclear antigen expression, which was associated with decreased nuclear binding of p53. Compared with control, C. pneumoniae inoculation resulted in a 2.5-fold increase in released interleukin-6 and interleukin-8. In each experiment, the influence of C. pneumoniae was abrogated by concomitant treatment with the macrolide antibiotic azithromycin. CONCLUSIONS: C. pneumoniae induced human vascular smooth muscle cell proliferation and proliferating cell nuclear antigen expression, down-regulated p53, and promoted release of prototypical atherogenic cytokines. These in vitro findings indicate that C. pneumoniae is more than an innocent bystander, rather it is a pathophysiologic participant in atherogenesis warranting elimination.

Arteriosclerosis↗
PubMed2003

Living donor liver transplantation in patients with hepatitis C.

1. Hepatitis C virus (HCV) is the most common indication for living donor liver transplantation (LDLT). 2. Preliminary evidence suggests that HCV may occur earlier and may be more severe in LDLT recipients. However, current data is inconclusive relative to the impact of recurrent HCV on patient and graft survival in LDLT recipients. 3. Potential mechanisms for differences in severity of HCV in LDLT recipients are discussed. 4. LDLT remains a viable treatment option for selected patients with HCV.

Antiviral Agents↗
PubMed2002

Monocyte chemotactic protein-1 directly induces human vascular smooth muscle proliferation.

Although monocyte chemotactic protein-1 (MCP-1) is best known for its ability to recruit mononuclear cells, few studies have examined the effects of this chemokine on other events in the vascular response to injury. The purpose of the present study was to determine the influence of MCP-1 on human vascular smooth muscle (VSMC) proliferation. MCP-1 induced concentration-dependent VSMC proliferation as measured by bromodeoxyuridine (BrdU) uptake. Direct cell counting demonstrated a twofold increase in VSMC after stimulation with MCP-1. This mitogenic effect was similar to that observed with the prototypical atherogenic cytokine platelet-derived growth factor. Immunohistochemistry and Western blot analysis revealed that MCP-1 increased both proliferating nuclear cell antigen and cyclin A expression. Whereas MCP-1 did not promote nuclear factor-kappaB activation, MCP-1-induced VSMC proliferation appeared to be dependent on phosphotidylinositol 3-kinase activation. In conclusion, MCP-1 directly induces VSMC growth, which is associated with activation of cell cycle proteins and intracellular proliferative signals. Within the inflammatory paradigm of vascular remodeling, these data suggest that MCP-1 is more than simply a chemokine but also a potent mitogen for VSMC proliferation.

Aorta, Thoracic↗
PubMed2002

Neutralization of IL-18 attenuates lipopolysaccharide-induced myocardial dysfunction.

Tumor necrosis factor-alpha (TNF-alpha) and interleukin-1beta (IL-1beta) have been implicated in cardiac dysfunction during endotoxemia. Because IL-18 is a proinflammatory cytokine known to mediate the production of TNF-alpha and IL-1beta and to induce the expression of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1), we hypothesized that neutralization of IL-18 would attenuate lipopolysaccharide (LPS)-induced cardiac dysfunction. Mice (C57BL/6) were injected with LPS (0.5 mg/kg ip) or vehicle (normal saline), and left ventricular developed pressure (LVDP) was determined by the Langendorff technique. LVDP was depressed by 38% at 6 h after LPS. LPS-induced myocardial dysfunction was associated with increased myocardial levels of TNF-alpha and IL-1beta as well as increased expression of ICAM-1/VCAM-1. Pretreatment with neutralizing anti-mouse IL-18 antibody attenuated LPS-induced myocardial dysfunction (by 92%) and was associated with reduced myocardial IL-1beta production (65% reduction) and ICAM-1/VCAM-1 expression (50% and 35% reduction, respectively). However, myocardial TNF-alpha levels were not influenced by neutralization of IL-18. In conclusion, neutralization of IL-18 protects against LPS-induced myocardial dysfunction. IL-18 may mediate endotoxemic myocardial dysfunction through induction of and/or synergy with IL-1beta, ICAM-1, and VCAM-1.

Animals↗
PubMed2002

Interleukin-11 attenuates human vascular smooth muscle cell proliferation.

Interleukin (IL)-11 is a growth factor for megakaryocytes, osteoclasts, and intestinal mucosa. IL-11 is also an anti-inflammatory agent, mediating many of its effects by inhibition of the transcriptional activator nuclear factor (NF)-kappa B. The purposes of this study were to examine the effects of IL-11 on human vascular smooth muscle cell (VSMC) proliferation and NF-kappa B activity. VSMC were cultured from human transplant donor aortas, stimulated with basic fibroblastic growth factor (bFGF), and treated with IL-11. VSMC stimulated with bFGF demonstrated an increase in cell number by direct cell counting and mitochondrial activity. IL-11 caused a concentration-dependent decrease in bFGF-induced VSMC proliferation. Furthermore, IL-11 attenuated bFGF-induced increases in cytoplasmic and intranuclear unbound NF-kappa B p65. Similarly, IL-11 attenuated VSMC expression of two NF-kappa B-dependent cytokines, IL-8 and IL-6. Stimulated VSMC did not secrete IL-11, suggesting that endogenous IL-11 did not account for our observations. In conclusion, IL-11 inhibits human VSMC proliferation in vitro and is associated with suppression of NF-kappa B.

Aorta↗
PubMed2002

Lack of TNF-alpha attenuates intimal hyperplasia after mouse carotid artery injury.

This study sought to determine the influence of tumor necrosis factor-alpha (TNF-alpha) on intimal hyperplasia (IH) and characterize the mechanisms of transcriptional regulation after vascular injury. A murine model of wire carotid artery injury was employed to induce IH in wild-type (WT) and TNF-alpha-deficient [TNF(-/-)] animals. Three days after injury, TNF-alpha and nuclear factor-kappaB (NF-kappaB) protein expression was markedly increased in the injured WT carotid artery compared to control. Injury increased TNF-alpha and NF-kappaB mRNA expression 100- and 7.5-fold, respectively. Compared with WT specimens, injury in TNF(-/-) animals decreased both NF-kappaB mRNA and protein nearly 7.5- and 4-fold, respectively. Expression of the NF-kappaB-dependent cytokine monocyte chemotactic protein 1 was markedly diminished in injured TNF(-/-) animals. Finally, TNF(-/-) animals demonstrated a sevenfold reduction in IH compared with WT animals. Cumulatively, these data mechanistically link TNF-alpha and NF-kappaB in vivo and suggest an important influence of TNF-alpha on postinjury IH.

Animals↗
PubMed2002

ICAM-1 and VCAM-1 mediate endotoxemic myocardial dysfunction independent of neutrophil accumulation.

Both intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) have been implicated in neutrophil-mediated lung and liver injury during sepsis. However, the role of these adhesion molecules as well as the contribution of neutrophils in myocardial dysfunction during sepsis remains to be determined. The purpose of this study was to examine the role of ICAM-1, VCAM-1, and neutrophils in lipopolysaccharide (LPS)-induced myocardial dysfunction. Mice were subjected to LPS (0.5 mg/kg ip) or vehicle (normal saline), and left ventricular developed pressure (LVDP) was determined by the Langendorff technique. LVDP was depressed by nearly 40% at 6 h after LPS. Immunofluorescent staining revealed a temporal increase in myocardial ICAM-1/VCAM-1 expression and neutrophils after LPS. Antibody blockade of VCAM-1 reduced myocardial neutrophil accumulation and abrogated LPS-induced cardiac dysfunction. Antibody blockade or absence of ICAM-1 (gene knockout) also abrogated LPS-induced cardiac dysfunction but did not reduce neutrophil accumulation. Neutrophil depletion (vinblastine or antibody) did not protect from LPS-induced myocardial dysfunction. Our results suggest that although endotoxemic myocardial dysfunction requires both ICAM-1 and VCAM-1, it occurs independent of neutrophil accumulation.

Animals↗
PubMed2002

Vasopressin in cardiovascular patients: therapeutic implications.

Vasopressin is a vital homeostatic protein which regulates fluid balance via its antidiuretic effects and vascular tone via its vasoconstrictive effects. Endogenous vasopressin deficiency has been implicated in several disease states resulting in vasodilatory shock. In particular, vasopressin levels are low in patients following cardiac surgery and in those with ventricular dysrhythmias. Several recent studies have demonstrated the effectiveness of exogenous vasopressin in providing haemodynamic support in patients with postcardiopulmonary bypass vasodilatory shock and refractory ventricular fibrillation. This manuscript reviews the pathophysiological and clinical basis for vasopressin replacement in patients with cardiovascular collapse.

Cardiopulmonary Resuscitation↗