Steve K. Landas

Spatial Distribution of Fibrosis Governs Fibrillation Wave Dynamics in the Posterior Left Atrium During Heart Failure

Heart failure (HF) commonly results in atrial fibrillation (AF) and fibrosis, but how the distribution of fibrosis impacts AF dynamics has not been studied. HF was induced in sheep by ventricular tachypacing (220 bpm, 6 to 7 weeks). Optical mapping (Di-4-ANEPPS, 300 frames/sec) of the posterior left atrial (PLA) endocardium was performed during sustained AF (burst pacing) in Langendorff-perfused HF (n=7, 4 &mgr;mol/L acetylcholine; n=3, no acetylcholine) and control (n=6) hearts. PLA breakthroughs were the most frequent activation pattern in both groups (72.0±4.6 and 90.2±2.7%, HF and control, respectively). However, unlike control, HF breakthroughs preferentially occurred at the PLAs periphery near the pulmonary vein ostia, and their beat-to-beat variability was greater than control (1.93±0.14 versus 1.47±0.07 changes/[beats/sec], respectively, P<0.05). On histological analysis (picrosirius red), the area of diffuse fibrosis was larger in HF (23.4±0.4%) than control (14.1±0.6%; P<0.001, n=4). Also the number and size of fibrous patches were significantly larger and their location was more peripheral in HF than control. Computer simulations using 2-dimensional human atrial models with structural and ionic remodeling as in HF demonstrated that changes in AF activation frequency and dynamics were controlled by the interaction of electrical waves with clusters of fibrotic patches of various sizes and individual pulmonary vein ostia. During AF in failing hearts, heterogeneous spatial distribution of fibrosis at the PLA governs AF dynamics and fractionation.

Expression of prostate-specific membrane antigen in normal and malignant human tissues.

BackgroundProstate-specific membrane antigen (PSMA) is upregulated in androgen-dependent prostate carcinoma and it has been targeted for immunotherapy and diagnosis of this cancer. However, this protein is also expressed in other tissues. The objective of this study is to investigate its expression in normal and malignant human tissues.MethodsUsing monoclonal antibodies 24.4E6 (specific for residues 638–657) and 7E11.C5 (specific for the transmembrane domain of PSMA), immunohistochemical detection of PSMA was performed in surgical specimens.ResultsProstate-specific membrane antigen was detected in the epithelium of prostate, urinary bladder, proximal tubules of kidney, liver, esophagus, stomach, small intestine, colon, breast, fallopian tubes and testicular seminiferous tubules, hippocampal neurons and astrocytes, ependyma, cortex and medulla of the adrenal gland, and ovary stroma. It was also detected in neoplasms of the prostate, kidney, urinary bladder, stomach, small intestine, colon, lung, adrenal gland, and testis. It was not detected in normal seminal vesicles or the lung.ConclusionsThese findings demonstrate that PSMA is widely distributed in normal tissues, and, depending on the tumors, its expression is up- or down-regulated, or unchanged. The broad distribution of PSMA may make it suitable for the diagnosis and therapy of a wide variety of tumors.

Metalloproteinase inhibition reduces lung injury and improves survival after cecal ligation and puncture in rats

BACKGROUND Neutrophil activation with concomitant matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9) release has been implicated in the development of sepsis-induced acute lung injury. We hypothesized that COL-3, a chemically modified tetracycline known to inhibit MMP-2 and MMP-9, would reduce lung injury and improve survival in rats following cecal ligation and puncture (CLP). METHODS Sprague-Dawley rats were separated into five groups: 1) sham CLP+ carboxymethylcellulose (CMC; vehicle for COL-3, n = 6); 2) sham CLP + COL-3 (n = 6); 3) CLP + CMC (n = 10); 4) CLP + single-dose (SD) COL-3 administered concomitant with CLP (n = 9); and 5) CLP + multiple-dose (MD) COL-3 administered concomitant with CLP and at 24 h after CLP (n = 15). Rats were sacrificed at 168 h (7 days) or immediately after death, with survival defined as hours after CLP. Histological lung assessment was made based on neutrophil infiltration, alveolar wall thickening, and intraalveolar edema fluid. Lung MMP-2 and MMP-9 levels were assessed by immunohistochemistry. MMP-2 and MMP-9 levels were correlated with survival by simple regression analysis. RESULTS The mortality of rats in the cecal ligation and puncture without treatment group (CLP + CMC) was 70% at 168 h. A single dose of COL-3 in the CLP + COL-3 (SD) group significantly reduced mortality to 54%. Furthermore, with a repeat dose of COL-3 at 24 h after CLP, mortality was significantly reduced to 33%. Pathologic lung changes seen histologically in the CLP + CMC group were significantly reduced by COL-3. A significant reduction in lung tissue levels of MMP-2 and MMP-9 was noted in both groups treated with COL-3. Reduction of MMP-2 and MMP-9 levels correlated with improved survival. CONCLUSION Inhibition of MMP-2 and MMP-9 by COL-3 in a clinically relevant model of sepsis-induced acute lung injury reduces pulmonary injury and improves survival in a dose-dependent fashion. Our results suggest that prophylactic treatment with COL-3 in high-risk patients may reduce the morbidity and mortality associated with sepsis-induced acute respiratory distress syndrome.

Acute gastritis associated with spiral organisms from cats

Numerous studies implicateHelicobacter pylori as one causative agent producing gastritis and dyspepsia. Recent reports focus on another bacterium,Gastrospirillum hominis, as a possible pathogen producing gastritis. We report a 30-year-old researcher who became acutely ill with epigastric pain indicative of esophagitis or peptic ulcer disease. Gastritis and a gastric ulcer were observed endoscopically. Histological examination of the gastric mucosa revealed an acute gastritis and large spiral-shaped organisms. The spiral forms were present in large quantities in the gastric mucosa of experimental animals (cats) handled by the patient in his research. Electron microscopy confirmed that the organisms from the cat and patient were morphologically identical. The patient was successfully treated with bismuth subsalicylate. His symptoms resolved and the organisms were cleared from his stomach. This study provides evidence that another bacterium, aGastrospirillum, may cause gastritis in man and may be transmitted from animal to man.

Immune markers and differential signaling networks in ulcerative colitis and Crohn's disease†

Background: Cytokine signaling pathways play a central role in the pathogenesis of inflammatory bowel disease (IBD). Ulcerative colitis (UC) and Crohns disease (CD) have unique as well as overlapping phenotypes, susceptibility genes, and gene expression profiles. This study aimed to delineate patterns within cytokine signaling pathways in colonic mucosa of UC and CD patients, explore molecular diagnostic markers, and identify novel immune mediators in IBD pathogenesis. Methods: We quantified 70 selected immune genes that are important in IBD signaling from formalin‐fixed, paraffin‐embedded (FFPE) colon biopsy samples from normal control subjects and UC and CD patients having either severe colitis or quiescent disease (n = 98 subjects). We utilized and validated a new modified real‐time reverse‐transcription polymerase chain reaction (RT‐PCR) technique for gene quantification. Results: Expression levels of signaling molecules including IL‐6/10/12/13/17/23/33, STAT1/3/6, T‐bet, GATA3, Foxp3, SOCS1/3, and downstream inflammatory mediators such as chemokines CCL‐2/11/17/20, oxidative stress inducers, proteases, and mucosal genes were differentially regulated between UC and CD and between active and quiescent disease. We also document the possible role of novel genes in IBD, including SHP‐1, IRF‐1,TARC, Eotaxin, NOX2, arginase I, and ADAM 8. Conclusions: This comprehensive approach to quantifying gene expression provides insights into the pathogenesis of IBD by elucidating distinct immune signaling networks in CD and UC. Furthermore, this is the first study demonstrating that gene expression profiling in FFPE colon biopsies might be a practical and effective tool in the diagnosis and prognosis of IBD and may help identify molecular markers that can predict and monitor response to individualized therapeutic treatments. (Inflamm Bowel Dis 2012;)

OXIDATIVE STRESS, INFLAMMATION AND CARCINOGENESIS ARE CONTROLLED THROUGH THE PENTOSE PHOSPHATE PATHWAY BY TRANSALDOLASE

Metabolism of glucose through the pentose phosphate pathway (PPP) influences the development of diverse pathologies. Hemolytic anemia due to deficiency of PPP enzyme glucose 6-phosphate dehydrogenase is the most common genetic disease in humans. Recently, inactivation of another PPP enzyme, transaldolase (TAL), has been implicated in male infertility and fatty liver progressing to steatohepatitis and cancer. Hepatocarcinogenesis was associated with activation of aldose reductase and redox-sensitive transcription factors and prevented by N-acetylcysteine. In this paper, we discuss how alternative formulations of the PPP with and without TAL reflect cell type-specific metabolic control of oxidative stress, a crucial source of inflammation and carcinogenesis. Ongoing studies of TAL deficiency will identify new molecular targets for diagnosis and treatment in clinical practice.

Role of nitric oxide and tumor necrosis factor on lung injury caused by ischemia/reperfusion of the lower extremities

PURPOSE Acute aortic occlusion with subsequent ischemia/reperfusion (I/R) of the lower extremities is known to predispose to lung injury. The pathophysiologic mechanisms of this injury are not clear. In the present study, we studied the role of tumor necrosis factor (TNF) and nitric oxide (NO) in lung injury caused by lower extremity I/R. METHODS A rat model in which the infrarenal aorta was cross-clamped for 3 hours followed by 1 hour of reperfusion was used. The rats were randomized into five groups: group 1, aorta exposed but not clamped; group 2, aorta clamped for 3 hours, followed by 1 hour of reperfusion; group 3, 1 mg/kg dexamethasone administered before the aorta was clamped; group 4, 25 mg aminoguanidine, a specific inducible NO synthase (iNOS) inhibitor, administered before the aorta was clamped; and group 5, 2 mg/kg TNFbp, a PEG-ylated dimeric form of the high-affinity p55 TNF receptor I (RI), administered before the aorta was clamped. NO concentration in the exhaled gas (ENO) was measured, as an index of NO production by the lung, in 30 minute intervals during I/R. Serial arterial blood samples for TNF assay were obtained during the course of the experiment. At the end of the experiment, the lungs were removed and histologically examined for evidence of injury. RESULTS ENO in group 2 increased from 0.7 +/- 0.3 ppb at baseline to 54.3 +/- 7.5 ppb at the end of ischemia and remained stable during reperfusion (54.6 +/- 8.5 ppb at the end of reperfusion). ENO production was blocked by aminoguanidine, by dexamethasone, and by TNFbp given before aortic occlusion. Serum TNF in groups 2, 3 and 4 increased rapidly during early ischemia, reaching its peak value 60 minutes after occlusion of the aorta, then gradually declined to baseline levels at the end of ischemia, and remained low during reperfusion. TNFbp decreased serum TNF concentration significantly when it was given before aortic occlusion. Histologic examination of the lungs at the end of the experiment revealed that aminoguanidine, dexamethasone, and TNFbp had a protective effect on the lungs. CONCLUSIONS Serum TNF increases rapidly during lower extremity ischemia and causes increased production of NO from the lung by upregulating iNOS. Increased NO is associated with more severe lung injury, and iNOS blockade has beneficial effects on the lung. TNF blockade before ischemia decreases NO production by the lung and attenuates lung injury. ENO can be used as an early marker of lung injury caused by lower extremity I/R.

Localized infections of 6-hydroxydopamine into lamina terminalis-associated structures: effects on experimentally induced drinking and pressor responses

Electrolytic lesions of tissues surrounding the anteroventral third ventricle (AV3V) or injections of the chemical neurotoxin, 6-hydroxydopamine (6-OHDA) into the lateral cerebral ventricles result in virtually identical deficits in response to a variety of dipsogenic and pressor challenges. These observations have led to the hypothesis that the integrity of catecholamine (CA) projections into the AV3V region is a prerequisite for elicitation of these thirst and blood pressure responses. This hypothesis was tested in 6-OHDA-injected rats following protocols designed to deplete CAs in discrete structures associated with the lamina terminalis. Post-injection response deficits, coupled with histofluorescent assessments of CA depletions in specific anterior forebrain nuclei, support the stated hypothesis. In addition, the findings indicate that thirst deficits to systemic as well as central dipsogenic challenges are both selective and dissociable and that 6-OHDA lesions of any of the more ventrally situated target nuclei result in significantly attenuated blood pressure responses to centrally injected angiotensin II.

Selective catecholamine depletion of structures along the ventral lamina terminalis: effects on experimentally-induced drinking and pressor responses

Ablation of the periventricular tissue of the anteroventral third ventricle (AV3V) or injection of the chemical neurotoxin, 6-hydroxydopamine (6-OHDA), into the structures along the ventral lamina terminalis will produce deficits in drinking and pressor responses to exogenous angiotensin II (ANG II). Centrally-applied 6-OHDA has been shown to result in widespread depletions of both adrenergic (i.e. both noradrenaline and adrenaline-containing) and dopaminergic neurons. Questions arise, therefore, as to whether a dopaminergic or adrenergic depletion is critical and the locus where reductions must occur. The present experiment was designed to investigate the specificity of the effects of 6-OHDA administration into lamina terminalis-associated structures on ANG II-induced drinking and pressor responses. The nature of the depletion was manipulated with desmethylimipramine (DMI), a drug which blocks the uptake of 6-OHDA into adrenergic but not dopaminergic nerve terminals and thereby spares adrenergic elements. The experimental results indicate that 6-OHDA administration into structures of the ventral lamina terminalis produced ANG II response deficits and marked reductions in catecholamine histofluorescence in the regions of the injection sites. In contrast, pretreatment with DMI protected against the 6-OHDA-produced functional deficits and minimized the effects on histofluorescence. These findings are consistent with the interpretation that adrenergic but not dopaminergic neurons must be present in the structures of the ventral lamina terminalis in order to elicit normal angiotensin-induced drinking and pressor responses.

Atrial myxomas: Pathologic types, tumor location, and presenting symptoms

Abstract  Background: Atrial myxoma is the most common cardiac neoplasm. Although not widely reported, two anatomic types have been observed: solid and papillary. We examined whether differences in gross or microscopic appearance and location correlated with symptomatology, specifically congestive heart failure (CHF), neurologic symptoms, and embolic events. Methods: We performed a retrospective review of atrial myxomas removed from 1972 to 2002, recording the clinical presentation, diagnostic modality, tumor location, gross, and microscopic features for each patient. Twenty‐six patients (16 females and 10 males) had atrial myxomas excised. Two patients (one female and one male) were excluded due to unavailable pathologic slides. Results: In 24 patients there were 15 solid and 9 papillary tumors. CHF was more prevalent in solid myxomas, while neurologic symptoms and embolic events were more common in papillary tumors. Tumor location further correlated with presenting symptoms. Ninety‐two percent of patients presenting with CHF had tumors attached to the atrial septum. Extraseptal myxomas more frequently presented with neurologic (80% vs. 29%) and embolic features (50% vs. 25%). All patients exhibiting clefted tumor surface had a history of embolization. A higher percentage of solid myxomas (93%) showed hemorrhage within the tumor than with papillary (56%). Conclusions: CHF was more common with solid myxomas, and neurologic and embolization events were more common in the papillary type. Septal tumor location showed strong association with CHF, while extraseptal location correlated with neurologic events. We speculate that the various gross and microscopic patterns reflect secondary changes within these neoplasms over the course of their natural history.