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Biomedical subjects

Robert M Weiss

Publications and source records attributed to Robert M Weiss.

At least 37 records · Page 2Linked to original sources

Brain angiotensin-converting enzyme activity and autonomic regulation in heart failure.

Several recent studies suggest an important role for the brain renin-angiotensin system in the pathogenesis of heart failure. Angiotensin-converting enzyme (ACE) activity and binding of angiotensin type 1 (AT1) receptors, which mediate the central effects of ANG II, are increased in heart failure. The present study examined the relationship between brain ACE activity and the autonomic dysregulation characteristic of rats with congestive heart failure. Rats with heart failure (HF) induced by coronary artery ligation and sham-operated control (SHAM) rats were treated with chronic (28 days) third cerebral ventricle [intracerebroventricular (ICV)] or intraperitoneal (IP) infusion of a low dose of the ACE inhibitor enalaprilat (ENL) or vehicle (VEH). VEH-treated HF rats had increased sodium consumption, reduced urine sodium and urine volume, and increased sympathetic nerve activity with impaired baroreflex regulation. These responses were minimized or prevented by ICV ENL started 24 h after coronary ligation. IP ENL at the low dose used in these studies had no beneficial effects on HF rats. Neither IP nor ICV ENL had any substantial effect on the SHAM rats. The findings confirm a critically important contribution of the brain renin-angiotensin system to the pathophysiology of congestive heart failure.

Angiotensin-Converting Enzyme Inhibitors↗

DITPA stimulates arteriolar growth and modifies myocardial postinfarction remodeling.

Myocardial infarction (MI) is characterized by ventricular remodeling, hypertrophy of the surviving myocardium, and an insufficient angiogenic response. Thyroxine is a powerful stimulus for myocardial angiogenesis. Male rats that underwent coronary artery ligation and subsequent MI were given 3,5-diiodothyropropionic acid (DITPA; MI+DITPA group) during a 3-wk period. We evaluated ventricular remodeling using echocardiography and histology and myocardial vessel growth using image analysis. Protein expression was assessed using Western blotting and immunohistochemistry. This study tested the hypothesis that the thyroxine analog DITPA facilitates angiogenesis and influences postinfarction remodeling in the surviving hypertrophic myocardium. The increase in the region of akinesis (infarct expansion) was blunted in the MI+DITPA rats compared with the MI group (3 vs. 21%); the treated rats had smaller percent increases in the left ventricular (LV) volume (64 +/- 14 vs. 95 +/- 12) and the LV volume-to-mass ratio (47 +/- 13 vs. 84 +/- 10) as well as a blunted decrease in ejection fraction (-9 +/- 8 vs. -30 +/- 7%). Arteriolar length density was higher after treatment in the largest (>50% of the free wall) infarcts (64 +/- 3 vs. 43 +/- 7). Angiogenic growth factors [vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF)] and the angiopoietin receptor tyrosine kinase with immunoglobulin and epidermal growth factor homology domains (Tie-2) values were elevated during the first week after infarction. DITPA did not cause additional increases in VEGF or Tie-2 values but did induce an increase in bFGF value after 3 days of treatment. This study provides the first evidence for an anatomical basis, i.e., attenuated ventricular remodeling and arteriolar growth, for improved function attributed to DITPA therapy of the infarcted heart. The favorable influences of DITPA on LV remodeling after large infarction are principally due to border zone preservation.

Animals↗

Acute myocardial infarction induces hypothalamic cytokine synthesis.

The inflammatory milieu of acute myocardial infarction (MI) is theoretically conducive to enhanced cytokine synthesis within the brain. We tested the hypothesis that synthesis of tumor necrosis factor-alpha (TNF-alpha), an indicator of proinflammatory cytokine activity, increases in brain after MI. MI was induced in rats by ligating the left anterior descending coronary artery and confirmed by echocardiography. Plasma and tissue levels of TNF-alpha were measured using ELISA; TNF-alpha mRNA was measured with real-time PCR. Heart, brain, and plasma samples were obtained 0.5, 1, 4, or 24 h or 4 wk after MI. TNF-alpha synthesis increased in the brain, heart, and plasma within minutes to hours after MI and was sustained over the interval tested. Among the brain tissues examined, TNF-alpha increased selectively in hypothalamus. Chronic treatment with pentoxifylline prevented the increases in TNF-alpha in brain, heart, and plasma measured 4 wk after MI. MI-induced cytokine synthesis in the hypothalamus and its prevention by pentoxifylline have important implications in the context of the development of heart failure after MI.

Animals↗

Abnormal coronary function in mice deficient in alpha1H T-type Ca2+ channels.

Calcium ion (Ca2+) influx through voltage-gated Ca2+ channels is important for the regulation of vascular tone. Activation of L-type Ca2+ channels initiates muscle contraction; however, the role of T-type Ca2+ channels (T-channels) is not clear. We show that mice deficient in the alpha1H T-type Ca2+ channel (alpha(1)3.2-null) have constitutively constricted coronary arterioles and focal myocardial fibrosis. Coronary arteries isolated from alpha(1)3.2-null arteries showed normal contractile responses, but reduced relaxation in response to acetylcholine and nitroprusside. Furthermore, acute blockade of T-channels with Ni2+ prevented relaxation of wild-type coronary arteries. Thus, Ca2+ influx through alpha1H T-type Ca2+ channels is essential for normal relaxation of coronary arteries.

Acetylcholine↗

Differential role of tissue factor pathway inhibitors 1 and 2 in melanoma vasculogenic mimicry.

Vasculogenic mimicry (VM), the formation of matrix-rich vascular-like networks in three-dimensional culture corresponding with the expression of vascular cell-associated genes, and the lining of matrix-rich networks in situ, has been observed in highly aggressive and malignant melanoma. However, little is known about the molecular underpinnings of this phenomenon. On the basis of gene profiling, protein detection, and immunohistochemistry, aggressive relative to poorly aggressive melanoma showed up-regulation of tissue factor (TF), TF pathway inhibitor 1 (TFPI-1) and 2 (TFPI-2), critical genes that initiate and regulate the coagulation pathways. The procoagulant function of TF on highly aggressive melanoma is shown to be regulated by TFPI-1 but not by TFPI-2. Thus, aggressive melanoma exhibits endothelial cell-like anticoagulant mechanisms that may contribute to the fluid-conducting potential of melanoma cell-lined networks, as studied by correlative in vivo Doppler flow measurements. Antibody inhibition experiments reveal that TFPI-2 is required for VM in vitro, but plasmin is an unlikely target protease of TFPI-2. Blockade of TFPI-2 suppressed matrix metalloproteinase-2 activation, and, therefore, TFPI-2 appears to regulate an essential pathway of VM. TFPI-2 is synthesized by endothelial and tumor cells, which deposit TFPI-2 into extracellular matrices. Culturing poorly aggressive melanoma cells on three-dimensional matrix containing recombinant TFPI-2 produces some of the phenotypic changes associated with aggressive, vasculogenic melanoma cells. Thus, TFPI-2 contributes to VM plasticity, whereas TFPI-1 has anticoagulant functions of relevance for perfusion of VM channels formed by TF-expressing melanoma cells.

Animals↗

Developmental changes in the functional, biochemical and molecular properties of rat bladder endothelin receptors.

The effect of aging on functional, biochemical, anatomical and molecular properties of endothelin (ET) receptors in bladder smooth muscle of the 3-week-, 3-month- and 22-month-old rats was examined using isolated muscle bath techniques, radioligand binding on membrane particulates and slide mounted tissue sections, and real-time reverse transcription polymerase chain reaction (RT-PCR). ET-1 induced significantly larger contractile responses in bladder dome muscle strips from 3-week- than from 3-month- and 22-month-old rats. The expression level of total ET receptors, determined by saturation binding experiments with [(125)I]ET-1, was higher in detrusor from 3-week- than 22-month-old rats. Inhibition studies with BQ123, a selective ET(A) receptor antagonist, indicated the predominance of the ET(A) receptor subtype and a similar proportion of ET(A) to ET(B) receptor subtypes in the rat detrusor at all ages studied. Autoradiographic data support the age-dependent decrease in the density of ET receptors and also indicate that the ET(A) receptor subtype is primarily located in the smooth muscle layer, whereas the ET(B) receptor subtype is located in both the urothelial and smooth muscle layers. Determined by real-time RT-PCR, ET 1, ET-3, ECE-1 and ET receptor subtype (ET(A) and ET(B)) mRNAs were shown to be higher in bladders of 3-week- compared to 3-month- or 22-month-old rats. This study indicates age-dependent alterations in the ET receptor system at both gene transcript and protein levels in the Fischer rat detrusor.

Aging↗

Gene transfer of extracellular superoxide dismutase reduces arterial pressure in spontaneously hypertensive rats: role of heparin-binding domain.

Oxidative stress may contribute to hypertension. The goals of this study were to determine whether extracellular superoxide dismutase (ECSOD) reduces arterial pressure in spontaneously hypertensive rats (SHR) and whether its heparin-binding domain (HBD), which is responsible for cellular binding, is necessary for the function of ECSOD. Three days after intravenous injection of an adenoviral vector expressing human ECSOD (AdECSOD), mean arterial pressure (MAP) decreased from 165+/-4 mm Hg (mean+/-SE, n=7) to 124+/-3 mm Hg (n=7) in adult anesthetized SHR (P<0.01) but was not altered in normotensive Wistar-Kyoto rats. Cardiac output was not changed in SHR 3 days after AdECSOD. Gene transfer of ECSOD with deletion of the HBD (AdECSODDeltaHBD) had no effect on SHR MAP, even though plasma SOD activity was greater after AdECSODDeltaHBD than after AdECSOD. Immunohistochemistry revealed intense staining for ECSOD in blood vessels and kidneys after AdECSOD but not after AdECSODDeltaHBD. Impaired relaxation of the carotid artery to acetylcholine in SHR was significantly improved after AdECSOD. Cumulative sodium balance in SHR was reduced by AdECSOD compared with AdECSODDeltaHBD. Gene transfer of ECSOD also reduced MAP in conscious SHR, although the effect was not as profound as in anesthetized SHR. In summary, gene transfer of ECSOD, with a strict requirement for its HBD, reduces systemic vascular resistance and arterial pressure in a genetic model of hypertension. This reduction in arterial pressure may be mediated by vasomotor and/or renal mechanisms.

Adenoviridae↗

Urinary interleukin-8 levels are elevated in subjects with transitional cell carcinoma.

OBJECTIVES: Interleukin (IL)-8 is one of several angiogenic factors produced in bladder cancer cell lines. Although many studies have indicated that IL-8 is increased in infectious/inflammatory processes, elevated levels of IL-8 in urine also may be indicative of active transitional cell carcinoma (TCC). METHODS: Urinary IL-8 levels were measured with an enzyme-linked immunosorbent assay in subjects with TCC (n = 51), prostate cancer (n = 17), or a history of successfully treated TCC (n = 23) and in healthy subjects (n = 49). In addition, urinary IL-8 levels were measured in 21 subjects before, during, and 1 month after intravesical therapy with bacille Calmette-Guérin or mitomycin C. RESULTS: The median urinary IL-8 levels were greater in subjects with TCC (64 pg/mL urine) than in healthy subjects (6 pg/mL urine), subjects with prostate cancer (0.5 pg/mL urine), or subjects with a history of successfully treated TCC (5.0 pg/mL urine). Urinary IL-8 levels were greater in subjects with invasive (high-stage) TCC than in those with low-stage TCC. Furthermore, the postintravesical instillation levels of urinary IL-8 levels were greater in patients whose TCC recurred compared with those whose TCC was in remission. CONCLUSIONS: IL-8 levels were greater in subjects with TCC compared with those with successfully treated TCC. IL-8 levels increased with TCC stage, indicating that they are greater in more invasive (ie, angiogenic) tumors. A reduction in urinary IL-8 levels after treatment with bacille Calmette-Guérin or mitomycin C may reflect a decrease in bladder cancer cells and/or in other cells that produce IL-8.

Adenocarcinoma↗

Genetic redox preconditioning differentially modulates AP-1 and NF kappa B responses following cardiac ischemia/reperfusion injury and protects against necrosis and apoptosis.

Reactive oxygen species have been established as key mediators of cardiac injury following ischemia/reperfusion (I/R). We hypothesized that superoxide formation at different subcellular locations following cardiac I/R injury may differentially regulate cellular responses that determine pathophysiologic outcomes. Recombinant adenoviruses expressing Cu/ZnSOD or MnSOD were utilized to modulate superoxide levels in the cytoplasmic or mitochondrial compartments, respectively, prior to coronary artery I/R injury in the rat heart. Ectopic expression of both MnSOD and Cu/ZnSOD afforded protection from I/R injury, as evidenced by a significant reduction in serum creatine kinase levels, infarct size, malondialdehyde levels, and apoptotic cell death in comparison to controls. MnSOD and Cu/ZnSOD expression also significantly altered the kinetics of NF kappa B and AP-1 activation following I/R injury, characterized by a delayed induction of NF kappa B and abrogated AP-1 response. Western blot analysis of Bcl-2, Bcl-xL, Bad, Caspase 3, PDK1, and phospho-Akt also revealed SOD-mediated changes in gene expression consistent with protection and decreased apoptosis. These findings support the notion that both mitochondrial and cytoplasmic-derived SOD induce changes in AP-1 and NF kappa B activity, creating an antiapoptotic microenvironment within cardiomyocytes that affords protection following I/R injury.

Adenoviridae↗

Effect of intravesical treatment of transitional cell carcinoma with bacillus Calmette-Guerin and mitomycin C on urinary survivin levels and outcome.

PURPOSE: Urine survivin is a predictive/prognostic molecular marker that detects transitional cell carcinoma (TCC) with high specificity and sensitivity. The presence of urine survivin in patients with TCC who receive intravesical instillation of bacillus Calmette-Guerin or mitomycin C may predict recurrence. MATERIALS AND METHODS: Urine from 25 subjects receiving 27 intravesical treatments of bacillus Calmette-Guerin or mitomycin C for TCC were collected prior to, during and after treatment. Urinary survivin levels were compared with outcome, as assessed by cytology and cystoscopy with or without biopsy 1 month and up to 12 months after the completion of treatment. RESULTS: Pretreatment survivin levels were higher in subjects in whom TCC recurred following treatment compared with those who achieved remission. Survivin levels increased several-fold during treatment with the highest survivin levels measured in subjects with recurrence. Median posttreatment values of survivin were zero in those who achieved remission and 1.0 ng/ml urine in subjects in whom TCC recurred. CONCLUSIONS: The presence of urinary survivin 1 month after the completion of treatment predicts TCC recurrence with 100% sensitivity and 78% specificity. Specificity to predict TCC recurrence increases to 92% after 1 year. No TCC recurred for 1 year in 12 of the 14 subjects with a posttreatment survivin level of 0.1 ng or less per ml urine. Three of the 4 subjects who were survivin positive but in remission 1 month after the completion of treatment had recurrent TCC within 1 year. Subjects who have urinary survivin after the completion of intravesical instillation have a high likelihood of TCC recurrence.

Adjuvants, Immunologic↗

Heart failure and the brain: new perspectives.

Despite recent therapeutic advances, the prognosis for patients with heart failure remains dismal. Unchecked neurohumoral excitation is a critical element in the progressive clinical deterioration associated with the heart failure syndrome, and its peripheral manifestations have become the principal targets for intervention. The link between peripheral systems activated in heart failure and the central nervous system as a source of neurohumoral drive has therefore come under close scrutiny. In this context, the forebrain and particularly the paraventricular nucleus of the hypothalamus have emerged as sites that sense humoral signals generated peripherally in response to the stresses of heart failure and contribute to the altered volume regulation and augmented sympathetic drive that characterize the heart failure syndrome. This brief review summarizes recent studies from our laboratory supporting the concept that the forebrain plays a critical role in the pathogenesis of ischemia-induced heart failure and suggesting that the forebrain contribution must be considered in designing therapeutic strategies. Forebrain signaling by neuroactive products of the renin-angiotensin system and the immune system are emphasized.

Animals↗

Central mineralocorticoid receptor blockade decreases plasma TNF-alpha after coronary artery ligation in rats.

The Randomized Aldactone Evaluation Study (RALES) demonstrated a substantial clinical benefit to blocking the effects of aldosterone (Aldo) in patients with heart failure. We recently demonstrated that the enhanced renal conservation of sodium and water in rats with heart failure can be reduced by blocking the central nervous system effects of Aldo with the mineralocorticoid receptor (MR) antagonist spironolactone (SL). Preliminary data from our laboratory suggested that central MR might contribute to another peripheral mechanism in heart failure, the release of proinflammatory cytokines. In the present study, SL (100 ng/h for 21 days) or ethanol vehicle (Veh) was administered via the 3(rd) cerebral ventricle to one group of rats after coronary ligation (CL) or sham CL (Sham) to induce congestive heart failure (CHF). In Veh-treated CHF rats, tumor necrosis factor-alpha (TNF-alpha) levels increased during day 1 and continued to increase throughout the 3-wk observation period. In CHF rats treated with SL, started 24 h after CL, TNF-alpha levels rose initially but retuned to control levels by day 5 after CL and remained low throughout the study. These findings suggest that activation of MR in the central nervous system plays a critical role in regulating TNF-alpha release in heart failure rats. Thus some of the beneficial effect of blocking MR in heart failure could be due at least in part to a reduction in TNF-alpha production.

Aldosterone↗

Cytokine mediation of experimental heart failure-induced anhedonia.

Immune system dysfunction is hypothesized to influence several disease states, including cardiovascular disease and psychological depression. The comorbidity of depression and coronary artery disease may be influenced by immune system-brain interactions involving proinflammatory cytokines. The present studies evaluated an index of depression in a rodent model of heart failure by measuring responses to rewarding electrical brain stimulation, which provides an experimental procedure to operationally define anhedonia in rats. Heart failure led to a rightward shift in the current-response relationship in the brain stimulation paradigm, indicative of reduced rewarding properties of the brain stimulation (i.e., anhedonia). Acute treatment with a tumor necrosis factor antagonist, etanercept, reduced circulating tumor necrosis factor- levels in rats with heart failure and restored responding for electrical brain stimulation. The current findings have implications for the study of pathophysiological mechanisms underlying the association of cardiovascular disease and depression.

Animals↗

The effect of castration on endothelins, their receptors and endothelin converting enzyme in rat prostate.

We previously have shown that experimental diabetes in rats causes prostatic involution, reduces serum testosterone levels, and causes an upregulation in prostatic endothelin (ET) receptors. Furthermore, insulin treatment normalizes these changes (Saito et al., Mol Cell Biochem 210:1-12, 2000). Since experimental diabetes-induced reduction in serum testosterone may be a factor in the alteration of the ET receptors and of prostatic growth, we investigated the effect of castration, another means of involuting the prostate and decreasing serum testosterone levels, on the expression of ET receptors in ventral and dorsolateral regions of the rat prostate.Three-month-old Sprague-Dawley rats were surgically castrated or sham operated, and then killed on the 7th post-operative day. Biochemical and pharmacological properties, and localization of ET receptors in the rat prostate, were determined by performing a series of binding experiments with [(125)I]ET-1 and by light microscopy autoradiography, respectively. The expression levels of ET-1, ET-3, ET receptor subtypes and endothelin converting enzyme-1 (ECE-1) mRNAs were assessed by relative multiplex reverse transcription polymerase chain reaction (RT-PCR). The total density of ET receptors increases 3.7-fold in the ventral and 2.1-fold in the dorsolateral regions of the castrated rat prostate compared to sham operated animals. Castration causes a 2.4-fold increase in the density of alpha(1)-adrenoceptors (alpha(1)-ARs) in the ventral region of the prostate, but no change in the density of alpha(1)-ARs in the dorsolateral region of the rat prostate. The predominant ET receptor subtype in the rat prostate is the ETA subtype, which is mainly located in the prostatic stroma. In addition, RT-PCR data show an upregulation in the expression of ETB receptor subtype, ET-1 and ECE-1 mRNA in both regions, and a downregulation in the expression of ETA receptor subtype mRNA in the dorsolateral region of the castrated rat prostate. There is no change in the expression of ET-3 mRNA in either region. Castration does not cause significant changes in the pharmacological properties of prostatic ET receptors, i.e., the predominance of ETA receptors in either region of the prostate, or the expression of ETA receptor subtype mRNA in the ventral region of the castrated rat prostate. These results suggest the existence of a region/lobe-specific regulatory role for testosterone in the expression of the ET receptor system in the rat prostate.

Animals↗

Bladder cancer detection with urinary survivin, an inhibitor of apoptosis.

The current "gold standard" for the diagnosis of bladder cancer is cystoscopy and urine cytology. Cystoscopy, a naked eye assessment of the bladder, is invasive, uncomfortable and costly while cytology has high specificity but low sensitivity (40-60%) particularly for low-grade lesions. Therefore, there is a need for a molecular tumor marker assay that is simple to perform and sensitive, particularly for low-grade lesions. By looking to the pathophysiology of bladder cancer, we identified survivin, an inhibitor of apoptosis that is not generally expressed in fully differentiated adult tissue and is highly expressed in bladder cancer. Survivin is detected in whole urine of patients with TCC using a simple antibody based test. The sensitivity of survivin testing for new or recurrent bladder cancer is 100% while the specificity for other neoplastic and non-neoplastic genitourinary disease is 95%. The high sensitivity of this simple, noninvasive test is well suited to bladder cancer, a disease with high rates of recurrence.

Apoptosis↗

Targeted inhibition of calcineurin in pressure-overload cardiac hypertrophy. Preservation of systolic function.

Calcineurin is a Ca(2+)/calmodulin-activated protein phosphatase that transduces hypertrophic stimuli to regulate transcriptional control of myocyte transformation. It is not known whether overexpression of MCIP1, a recently described endogenous inhibitor of calcineurin, impacts the hypertrophic response to pathophysiologically relevant pressure overload. Further, the functional consequences of calcineurin inhibition by MCIP1 under conditions of hemodynamic stress are unknown. Transgenic mice expressing a human cDNA encoding hMCIP1 in the myocardium were subjected to thoracic aortic banding. Transgenic mice and wild type littermates tolerated pressure overload equally well. Wild type mice developed left ventricular hypertrophy, but the hypertrophic response in transgenics was significantly blunted. An isoform of MCIP1 transcript was up-regulated by pressure stress, whereas MCIP2 transcript was not. Expression patterns of fetal genes were differentially regulated in banded MCIP1 hearts compared with wild type. Echocardiography performed at 3 weeks and 3 months revealed preservation of both left ventricular size and systolic function in banded MCIP1 mice despite the attenuated hypertrophic response. These data demonstrate attenuation of hypertrophic transformation when calcineurin is inhibited by MCIP1. Further, these data suggest that activation of hypertrophic marker genes may not be directly dependent on calcineurin activity. Finally, they demonstrate that ventricular performance is preserved despite attenuation of compensatory hypertrophy.

Animals↗

Prostaglandin E2 production and cyclooxygenase-2 induction in human urinary tract infections and bladder cancer.

PURPOSE: Increased prostaglandin production correlates positively with cancer risk and cyclooxygenase (COX)-2, the inducible rate limiting enzyme for prostaglandin synthesis, is elevated in bladder cancer cases. Urinary prostaglandin levels and COX-2 expression in urine particulates may increase in urogenital cancer, including bladder cancer, and with infectious and inflammatory processes, including urinary tract infections and that resulting from bacillus Calmette-Guerin (BCG) treatment for bladder cancer. MATERIALS AND METHODS: Urinary prostaglandin E2 levels were measured in patients with a urinary tract infection before and after treatment, urogenital cancer (including bladder cancer), bladder cancer in remission and bladder cancer with BCG treatment. COX-1 and COX-2 mRNA and protein were assessed in the human ureter, in normal human bladder muscle and urothelium, and in urine particulates from patients with urinary tract infections, bladder cancer and bladder cancer with BCG treatment. RESULTS: COX-1 protein, and mRNA and COX-2 mRNA were expressed in the ureter, and bladder muscle and urothelium. Urinary prostaglandin E2 levels and COX-2 protein expression in urine particulates were elevated in patients with urinary tract infections and with bladder cancer compared with age matched controls. Successful treatment for urinary tract infections and bladder cancer lowers urinary prostaglandin E2 levels. Urinary prostaglandin E2 and COX-2 protein levels are elevated during BCG treatment. CONCLUSIONS: Increased urinary prostaglandin E2 production and COX-2 protein expression correlate with urogenital cancer, urinary tract infections and inflammatory processes, such as those induced by BCG. Patients in whom urinary tract infection was treated with antibiotics or in whom bladder cancer is in remission have reduced urinary prostaglandin E2 compared with those who have active disease.

Adult↗