PubMed Health⌕ Search

Biomedical subjects

Herbert B Tanowitz

Publications and source records attributed to Herbert B Tanowitz.

44 records · Page 3Linked to original sources
PubMed2002

Caveolin-1/3 double-knockout mice are viable, but lack both muscle and non-muscle caveolae, and develop a severe cardiomyopathic phenotype.

The caveolin gene family consists of caveolins 1, 2, and 3. Caveolins 1 and 2 are co-expressed in many cell types, such as endothelial cells, fibroblasts, smooth muscle cells and adipocytes, where they form a heteroligomeric complex. In contrast, the expression of caveolin-3 is muscle-specific. Thus, the expression of caveolin-1 is required for caveolae formation in non-muscle cells, while the expression of caveolin-3 drives caveolae formation in striated muscle cell types (cardiac and skeletal). To create a truly caveolae-deficient mouse, we interbred Cav-1 null mice and Cav-3 null mice to generate Cav-1/Cav-3 double-knockout (Cav-1/3 dKO) mice. Here, we report that Cav-1/3 dKO mice are viable and fertile, despite the fact that they lack morphologically identifiable caveolae in endothelia, adipocytes, smooth muscle cells, skeletal muscle fibers, and cardiac myocytes. We also show that these mice are deficient in all three caveolin gene products, as caveolin-2 is unstable in the absence of caveolin-1. Interestingly, Cav-1/3 dKO mice develop a severe cardiomyopathy. At 2 months of age, analysis of Cav-1/3 dKO hearts via gated magnetic resonance imaging reveals a dramatic increase in left ventricular wall thickness, as compared with Cav-1-KO, Cav-3 KO, and wild-type mice. Further functional analysis of Cav-1/3 dKO hearts via transthoracic echocardiography demonstrates hypertrophy and dilation of the left ventricle, with a significant decrease in fractional shortening. As predicted, Northern analysis of RNA derived from the left ventricle of Cav-1/3 dKO mice shows a dramatic up-regulation of the atrial natriuretic factor message, a well-established biochemical marker of cardiac hypertrophy. Finally, histological analysis of Cav-1/3 dKO hearts reveals hypertrophy, disorganization, and degeneration of the cardiac myocytes, as well as chronic interstitial fibrosis and inflammation. Thus, dual ablation of both Cav-1 and Cav-3 genes in mice leads to a pleiotropic defect in caveolae formation and severe cardiomyopathy.

Adipocytes↗
PubMed2002

Cardioprotective effects of verapamil on myocardial structure and function in a murine model of chronic Trypanosoma cruzi infection (Brazil Strain): an echocardiographic study.

Verapamil has been shown to attenuate the extent of myocardial injury in murine models of chronic Trypanosoma cruzi infection. Infected mice treated with verapamil have significantly lower myocardial expression of inducible nitric oxide synthase and cytokines and substantially less inflammatory infiltrate and myocyte necrosis at necropsy. In the present study, we examined the cardiac structural and functional correlates of verapamil treatment in CD1 mice infected with the Brazil strain of T. cruzi using serial transthoracic echocardiography. There were four groups: uninfected- untreated control, uninfected-verapamil-treated, infected-untreated control, and infected-verapamil-treated. Verapamil was given in drinking water (1 gm/l) continuously from the day of infection for a total of 120 days. Mice were evaluated at baseline, 40 and 150 days p.i. Mice in the untreated-infected group compared with the mice in the infected-verapamil-treated group showed thinning of the left ventricular wall (0.84 +/- 0.02-vs-0.92 +/- 0.04, P<0.05 mm), increase in the left ventricular end-diastolic diameter (3.27 +/- 0.15-vs-2.74 +/- 0.05 mm, P<0.05) and reduction in percent fractional shortening (37 +/- 2-vs-53 +/- 4%, P<0.05). No differences in these parameters were noted among mice in the uninfected-untreated and uninfected-verapamil-treated groups. Furthermore, right ventricular dilation was more severe in mice from the infected-untreated group as compared with those in the infected- verapamil-treated group (visual grade 1.9 +/- 0.4-vs-1.0 +/- 0.2, P<0.05). At necropsy, the extent of myocardial injury, as determined histologically, was significantly greater in the infected-untreated mice. These data provide cardiac structural and functional correlates for the previously observed cardioprotective effects of verapamil in chronic chagasic cardiomyopathy.

Animals↗
PubMed2002

Cardioprotective effects of phosphoramidon on myocardial structure and function in murine Chagas' disease.

Chagas' disease is an important cause of cardiomyopathy. Endothelin-1, a vasoactive peptide has been implicated in the pathogenesis of chagasic cardiomyopathy. C57BL/6 x 129sv and CD1 mice were thus, infected with trypomastigotes of Trypanosoma cruzi (Brazil strain) and these infected mice were compared with infected mice treated with phosphoramidon. This compound inhibits endothelin-converting enzyme and neutral endopeptidases and does not affect the growth of the parasite in culture. Phosphoramidon was given in a dose of 10mg/kg for the initial 15 days post-infection None of the C57Bl/6 x 129sv mice died as a result of infection. However, there was marked myocardial inflammation and fibrosis in infected, untreated mice. The hearts of the infected, phosphoramidon-treated mice showed significantly less pathology. Cardiac magnetic resonance imaging of infected mice revealed right ventricular dilation that was less severe in those treated with phosphoramidon. Phosphoramidon-treated CD1 mice survived the acute infection. Transthoracic echocardiography demonstrated left ventricular dilation and reduced percent fractional shortening and relative wall thickness. These alterations were also attenuated as a result of phosphoramidon treatment. These data suggest that endothelin-1 contributes to the pathogenesis of chagasic cardiomyopathy and interventions that inhibit the synthesis of endothelin-1 and/or neutral endopeptidase might have a protective effect on myocardial structure and function in murine Chagas' disease.

Animals↗
PubMed2002

Role of mitogen-activated protein kinases in inducible nitric oxide synthase and TNFalpha expression in human fetal astrocytes.

Astrocytes are important sources of proinflammatory mediators such as iNOS and TNFalpha in the diseased central nervous system. In previous studies, we showed that the cytokine IL-1 plays a critical role in the activation of human astrocytes to express TNFalpha and the inducible form of nitric oxide synthase (iNOS). In the present study, we have addressed the role of the MAP-kinase pathway in the signaling events leading to the induction of these genes. Treatment with SB203580, a specific inhibitor of p38 mitogen-activated protein kinases (MAPK), potently inhibited IL-1-mediated induction of iNOS and TNFalpha in cultures of human fetal astrocytes. In contrast, PD98059, an upstream inhibitor of the extracellular regulated kinase (ERK)1/2 pathway, had little or no effect. Interestingly, SB203580 reduced the mRNA expression for iNOS, TNFalpha, and IL-6, indicating inhibition prior to translation. Transfection of astrocytes with a dominant-negative Jun-NH(2)-terminal kinase (JNK) construct also reduced iNOS expression. Western blot analysis showed phosphorylated p38 and JNK in IL-1-activated astrocytes, and phosphorylated ERK in both resting and activated cells. Electrophoretic mobility shift assay (EMSA) showed that IL-1 induced NF-kappaB and AP-1 DNA complex formation in astrocytes, and that SB203580 inhibited AP-1 complex formation. Taken together, these results demonstrate the differential roles played by the three MAP kinases in human astrocyte inflammatory gene activation and point to a crucial function of p38 and JNK MAP kinases in IL-1-mediated astrocyte activation.

Astrocytes↗
PubMed2002

Role of cardiac myocyte-derived endothelin-1 in chagasic cardiomyopathy: molecular genetic evidence.

Trypanosoma cruzi is the aetiological agent of Chagas' disease, an important cause of chronic cardiomyopathy. We previously demonstrated a role for endothelin-1 (ET-1) in the pathogenesis of chagasic heart disease. In order to explore further the significance of ET-1 in chagasic heart disease, we infected ET-1 (flox/flox); alpha-MHC-Cre(+) (ET-1KO) mice, in which the ET-1 gene has been deleted from cardiac myocytes, with 10(4) T. cruzi (Brazil strain) trypomastigotes. As controls, we used ET-1 (flox/flox);Cre(-) (FLOX) and C57BL/6x129sv (WT) mice. All mice survived and were evaluated 150-160 days post-infection. Cardiac magnetic resonance imaging revealed a significant increase in right ventricular internal diameter in all infected animals except ET-1KO mice (control WT, 1.6+/-0.10 mm; infected WT, 2.8+/-0.15 mm; control FLOX, 2.04+/-0.02 mm; infected FLOX, 2.76+/-0.28 mm). There was no significant difference in right ventricular internal diameter between infected and uninfected ET-1KO mice (control ET-1KO, 1.83+/-0.11 mm; infected ET-1KO, 2.14+/-0.20 mm). In another series of experiments, transthoracic echocardiography was performed on uninfected as well as infected ET-1KO mice, and uninfected and infected FLOX mice. Both infected groups had an increased left ventricular end-diastolic diameter and reduced fractional shortening. In addition, relative wall thickness was also decreased in infected animals. However, the magnitude of these changes was less in infected ET-1KO mice. These data provide further support for a role for ET-1 in the pathogenesis of chronic chagasic heart disease, and indicate that cardiac myocytes are an important source of ET-1 in this disease.

Animals↗
PubMed2002

Phosphoramidon treatment improves the consequences of chagasic heart disease in mice.

Chagas' disease, caused by the protozoan parasite Trypanosoma cruzi, is an important cause of cardiomyopathy. Microvascular spasm and matrix dissolution, modulated by endothelin-1 (ET-1), is implicated in the pathogenesis of chagasic heart disease. To further elucidate the role of ET-1 in murine chagasic heart disease, C57BL/6 x 129sv mice were infected with T. cruzi (10(3) trypomastigotes of the Brazil strain). These mice are resistant to death during the acute phase but progress to chronic cardiomyopathy. Infected mice were compared with infected mice treated with phosphoramidon, a non-specific metalloprotease inhibitor that is also a potent inhibitor of endothelin-converting enzyme, at a dose of 10 mg/kg. Mice were treated with phosphoramidon for the initial 15 days post infection (PI). All mice were evaluated 200 days PI. Examination of infected, untreated mice revealed marked inflammation, vasculitis and fibrosis. The hearts of infected treated mice had significantly less pathology. Cardiac magnetic resonance imaging (MRI) revealed that right ventricular internal diameter (RVID) was significantly greater (P<0.05) in the infected untreated group (2.9+/-0.22 mm) as compared with the infected treated group (1.73+/-0.35 mm). In another experiment phosphoramidon treatment was also tested in CD1 mice, which have a high mortality during the acute phase of infection with 5 x 10(4) trypomastigotes of the Brazil strain. One group of CD1 mice was untreated while the other group received phosphoramidon for the initial 15 days PI. The mortality rate in untreated mice was 70% by day 35 PI, while all treated infected mice lived. The parasitemia in both groups was similar. The cardiac pathology was more severe in untreated mice. MRI revealed the RVID to be significantly greater in the untreated infected group as compared with the phosphoramidon-treated infected mice (2.74+/-0.03 mm versus 1.64+/-0.4 mm P<0.05). Transthoracic echocardiography revealed that the percentage fractional shortening was reduced in infected CD1 mice but not in those infected mice treated with phosphoramidon. There was no effect of phosphoramidon in uninfected mice. Phosphoramidon (100 microg/ml) had no effect on parasites in vitro. These data are consistent with the hypothesis that ET-1 contributes to the pathogenesis of murine chagasic cardiomyopathy and suggests that interventions targeting ET-1 would improve the outcome in chagasic heart disease.

Animals↗
PubMed2002

Hypereosinophilia and liver mass in an immigrant.

Human infection with the sheep liver fluke Fasciola hepatica is a global zoonosis that usually parallels the prevalence of infection in sheep and other ruminants. The disease is endemic in South and Central America, Puerto Rico, the Caribbean region, many parts of Africa, Asia, the Middle East, Australia, and China. There have been a number of focal outbreaks reported from Europe, including southern France and the Mediterranean region. Since acute fascioliasis has rarely been reported in the United States, physicians in this country frequently overlook the diagnosis. Therefore, we report a case of acute human fascioliasis and review the pathogenesis, diagnosis, and treatment of this disease in a recently arrived immigrant.

Adult↗