Employment Status of Patients Receiving Maintenance Dialysis - Peritoneal and Hemodialysis: A Cross-sectional Study.

The long-term dialysis therapy for end-stage renal disease takes a heavy toll of quality of life of the patient. Several factors such as fatigue and decreased physical capability, impaired social and mental functioning, contribute to this forlorn state. To meld maintenance dialysis treatment with a regular employment can be a serious test. A cross-sectional study of employment of patients on hemodialysis and peritoneal dialysis in a state government tertiary institute in South India was performed between June 2015 and December 2015. Patients who completed 3 months of regular dialysis were only included in the study. The number of patients on hemodialysis was 157 and on peritoneal dialysis was 69. The employment status before the initiation of dialysis was 60% (93 out of 155) and 63.7% (44 out of 69) in hemodialysis and peritoneal dialysis, respectively. After initiation, the loss of employment was observed in 44% (41 out of 93) in hemodialysis and 51.2% (26 out of 44) in peritoneal dialysis (P = 0.2604). Even though there was fall of absolute number of job holders in both the blue and white collar jobs, the proportion of jobholders in the white collar job holders improved. On univariate analysis, the factors which influenced the loss of employment were males, age between 50 and 60 years, number of comorbidities >2, illiteracy and blue collar versus white collar job before the initiation of dialysis. The majority of patients had the scores above 80 on Karnofsky performance scale and the majority belonged upper and middle classes than lower classes on modified Kuppuswamy's socioeconomic status scale; however, the loss of employment was also disproportionately high. There appeared a substantial difference in the attitude of the patients toward the employment. There was no difference between hemodialysis and peritoneal dialysis in the loss of employment of our patients.

Effect of light-emitting diode and halogen light curing on the micro-hardness of dental composite and resin-modified glass ionomer cement: an in vitro study.

AIMS: This in vitro study was conducted to evaluate and compare the micro-hardness of composite resin and resin-modified glass ionomer cement using light-emitting diode (LED) and halogen curing and also to inter-compare the effect of LED and halogen curing. MATERIALS AND METHODS: The study sample comprised of 4 stainless steel plates with a thickness of 2 mm. For these stainless steel plates, holes were made to a diameter of 3 mm. The samples were divided into 4 groups of 8 each and labeled as group I, group II, group III, group IV, thus making provision for the two different modes of light exposure. In each group, the hole was restored with its respective restorative material and cured with light-curing unit according to manufacturer instructions. The results were statistically analyzed using Mann-Whitney test. RESULTS AND CONCLUSION: It was concluded that the curing efficacy of the LED lamp was comparable to that of conventional halogen lamp, even with a 50% reduction in cure time, and resin composite (Filtek Z-250) presented the highest hardness values, whereas complete hardening of resin-modified glass ionomer cement (RMGIC) (Vitremer) was observed because of its self-curing system even after the removal of light source.

Vitamin D and bone mineral density status of healthy schoolchildren in northern India.

BACKGROUND: Current data on the prevalence of vitamin D deficiency in India are scarce. OBJECTIVE: We assessed the calcium-vitamin D-parathyroid hormone axis in apparently healthy children from 2 different socioeconomic backgrounds in New Delhi, India. DESIGN: Clinical evaluation for evidence of vitamin D deficiency was carried out in 5137 apparently healthy schoolchildren, aged 10-18 y, attending lower (LSES) and upper (USES) socioeconomic status schools. Serum calcium, inorganic phosphorus, alkaline phosphatase, 25-hydroxyvitamin D [25(OH)D], and immunoreactive parathyroid hormone were measured in 760 children randomly selected from the larger cohort. Bone mineral density of the forearm and the calcaneum was measured in 555 children by using peripheral dual-energy X-ray absorptiometry. RESULTS: Clinical evidence of vitamin D deficiency was noted in 10.8% of the children. Children in the LSES group had a significantly (P < 0.01) lower 25(OH)D concentration (10.4 +/- 0.4 ng/mL) than did those in the USES group (13.7 +/- 0.4 ng/mL). Concentrations of 25(OH)D <9 ng/mL were seen in 35.7% of the children (42.3% in LSES; 27% in USES; P < 0.01). Boys had significantly (P = 0.004) higher 25(OH)D concentrations than did girls. There was a significant negative correlation between the mean serum immunoreactive parathyroid hormone and 25(OH) D concentrations (r = -0.202, P < 0.001). Mean forearm bone mineral density was significantly (P < 0.01) higher in the USES group than in the LSES group. CONCLUSION: A high prevalence of clinical and biochemical hypovitaminosis D exists in apparently healthy schoolchildren in northern India.

Current perspectives of electrical remodeling and its therapeutic implications.

Electrical remodeling involves alterations in the electrophysiologic milieu of myocardium in various disease states, such as ventricular hypertrophy, heart failure, atrial tachyarrhythmias, myocardial ischemia, and infarction that are associated with cardiac arrhythmias. Although research in this area dates back to early part of the 19th century, we still lack the exact knowledge of ionic remodeling, the role of various genes and channel proteins, and their relevance for the newer antiarrhythmic therapies. Structural remodeling may also have an impact on the electrical remodeling process, although differences in both structural and electrical remodeling are associated with different disease states. Various electrophysiologic, cellular, and structural alterations, including anisotropic conduction, increased intracellular calcium levels, and gap junction remodeling predispose to increased dispersion of action potential duration and refractoriness. This constitutes a favorable substrate for early and late afterdepolarizations and reentrant arrhythmias. Studying the role of ionic remodeling in the initiation and propagation of cardiac arrhythmias has significant relevance for developing newer antiarrhythmic therapies, for identifying patients at risk of developing fatal arrhythmias, and for implementing effective preventive measures. Further research is required to understand the specific effects of individual ion channel remodeling, to understand the signal transduction mechanisms, and to address whether detrimental effects of electrical remodeling can be altered.

The role of nitric oxide and vasopressin in refractory right heart failure.

The standard treatment for right heart failure includes aggressive fluid resuscitation, inotropic agents, and avoiding drugs, such as diuretics or nitrates, or maneuvers that decrease pre-load. Even an increase in vagal tone caused by the insertion of a bladder catheter can acutely decrease preload and lead to cardiogenic shock. Other modalities include early reperfusion therapy and pacemaker implantation for complete heart block or loss of atrioventricular synchrony. Acute right heart failure carries a very high mortality because of the limited options available for its management. Among newer treatments, inhaled nitric oxide and intravenous vasopressin have shown promise for acute right ventricular failure.

Altered functional coupling of coronary K+ channels in diabetic dyslipidemic pigs is prevented by exercise.

Chronic hyperglycemia and hypercholesterolemia have been shown to alter ionic currents in vascular smooth muscle. We tested the hypothesis that the combined effect of hyperglycemia and hyperlipidemia (diabetic dyslipidemia) would increase the Ca2+-sensitive K+ (KCa) current as a compensatory response to an increase in intracellular Ca2+ concentration. We also hypothesized that exercise training would prevent this elevation in KCa current. Miniature Yucatan swine were randomly assigned to five groups: control, standard pig chow (C, n = 6); hyperlipidemic, high-fat pig chow (H, n = 5); diabetic, standard pig chow (D, n = 7); diabetic, high-fat pig chow ("diabetic dyslipidemic," DD, n = 12); and exercise-trained DD (DDX, n = 9). High-fat chow consisted of standard minipig chow supplemented with cholesterol (2%) and coconut oil. Increased coronary vasoconstriction assessed in vivo and in vitro in DD was prevented by exercise. Patch-clamp experiments performed on right coronary artery smooth muscle cells resulted in greater K+ current densities in the H, D, and DD groups vs. the DDX group between -10 and 40 mV. In fura 2-loaded cells, current activated by caffeine-induced Ca2+ release was greater in H, D, and DD compared with C and DDX (P < 0.05), whereas intracellular Ca2+ concentration was not different across groups. Finally, there were no differences in the KCa or Kv channel protein content between groups. These data indicate that hyperglycemia, hyperlipidemia, and diabetic dyslipidemia lead to elevated whole cell K+ current and increased functional coupling of KCa and Ca2+ release. Endurance exercise prevented increased coupling of Ca2+ release to KCa channel activation in diabetic dyslipidemia.

Increased endothelin-induced Ca2+ signaling, tyrosine phosphorylation, and coronary artery disease in diabetic dyslipidemic Swine are prevented by atorvastatin.

Endothelin-1 (ET-1) signaling mechanisms have been implicated in the pathogenesis of excess coronary artery disease in diabetic dyslipidemia. We hypothesized that in diabetic dyslipidemia ET-1-induced coronary smooth muscle calcium (Ca2+m) and tyrosine phosphorylation would be increased, and the lipid lowering agent, atorvastatin, would inhibit these increases. Male Yucatan miniature swine groups were treated for 20 weeks: normal low-fat fed control, high-fat/cholesterol fed (hyperlipidemic), hyperlipidemic made diabetic with alloxan (diabetic dyslipidemic), and diabetic dyslipidemic treated with atorvastatin (atorvastatin-treated). Blood glucose values were 5-fold greater in diabetic dyslipidemic and atorvastatin-treated versus control and hyperlipidemic. Total and low-density lipoprotein (LDL) plasma cholesterol in hyperlipidemic, diabetic dyslipidemic, and atorvastatin-treated were approximately 5-fold greater than control. Intravascular ultrasound detectable coronary disease and hypertriglyceridemia were only observed in diabetic dyslipidemic and were abolished by atorvastatin. In freshly isolated cells, the Ca2+m response to ET-1 in diabetic dyslipidemic was greater than in control, hyperlipidemic, and atorvastatin-treated groups. Selective ET-1 receptor antagonists showed in the control group that the ETB subtype inhibits ETA regulation of Ca2+m. There was almost a complete switch of receptor subtype regulation of Ca2+m from largely ETA in control to an increased inhibitory interaction between ETA and ETB in hyperlipidemic and diabetic dyslipidemic groups, such that neither ETA nor ETB antagonist alone could block the ET-1-induced Ca2+m response. The inhibitory interaction was attenuated in the atorvastatin-treated group. In single cells, basal and ET-1-induced tyrosine phosphorylation in diabetic dyslipidemic were more than 3- and 6-fold greater, respectively, than in control, hyperlipidemic, and atorvastatin-treated. Attenuation by atorvastatin of coronary disease and ET-1-induced Ca2+m and tyrosine phosphorylation signaling with no change in cholesterol provides strong evidence for direct actions of atorvastatin and/or triglycerides on the vascular wall.

Left main coronary artery rotational atherectomy and stenting.

BACKGROUND: Coronary artery bypass surgery is a difficult option in patients who are not candidates for bypass surgery and high-risk patients with critical left main coronary artery (LMCA) disease. We report outcomes and short-term follow-up of patients who had LMCA rotational atherectomy and/or stenting, assess the role of these interventions in protected and unprotected significant LMCA stenosis, and review the literature. METHODS: We reviewed the cases of seven men with critical LMCA stenosis for whom coronary artery bypass surgery was considered a high risk. Five patients had rotational atherectomy, one had coronary artery stenting, and one had both. RESULTS: In all cases, angiographic success was achieved, and symptoms were relieved. Six patients were discharged from the hospital in 3 to 6 days. One patient who had cardiogenic shock, respiratory failure, and acute renal failure before the procedure died of arrhythmia 4 days afterward. Another patient had elective coronary artery bypass graft surgery 3 weeks later for recurrent angina. Cardiac catheterization was repeated in 1 month for chest pain in three patients at 4 to 7 months follow-up, and none had progression of residual stenosis in the LMCA. CONCLUSIONS: Our study suggests that LMCA rotational atherectomy and stenting are safe and effective revascularization procedures in high-risk patients and patients who are not candidates for bypass surgery.

The heartmate left ventricular assist system: first successful implantation in Missouri.

We report a case of the first successful implantation of the HeartMate left ventricular assist system as a bridge to heart transplant in the state of Missouri. Indications, technique of insertion, patient selection, outcomes and future applications are discussed.

Differential gene expression of extracellular matrix components in dilated cardiomyopathy.

Extracellular matrix metalloproteinases (MMPs) are activated in dilated cardiomyopathic (DCM) hearts [Tyagi et al. (1996): Mol Cell Biochem 155:13-21]. To examine whether the MMP activation is occurring at the gene expression level, we performed differential display mRNA analysis on tissue from six dilated cardiomyopathy (DCM) explanted and five normal human hearts. Specifically, we identified three genes to be induced and several other genes to be repressed following DCM. Southern blot analysis of isolated cDNA using a collagenase cDNA probe indicated that one of the genes induced during DCM was interstitial collagenase (MMP-1). Northern blot analysis using MMP-1 cDNA probe indicated that MMP-1 was induced three- to fourfold in the DCM heart as compared to normal tissue. To analyze posttranslational expression of MMP and tissue inhibitor of matrix metalloproteinase (TIMP) we performed immunoblot, immunoassay, and substrate zymographic assays. TIMP-1 and MMP-1 levels were 37 +/- 8 ng/mg and 9 +/- 2 ng/mg in normal tissue specimens (P < 0.01) and 2 +/- 1 ng/mg and 45 +/- 11 ng/mg in DCM tissue (P < 0.01), respectively. Zymographic analysis demonstrated lytic bands at 66 kDa and 54 kDa in DCM tissue as compared to one band at 66 kDa in normal tissue. Incubation of zymographic gel with metal chelator (phenanthroline) abolished both bands suggesting activation of neutral MMP in DCM heart tissue. TIMP-1 was repressed approximately twentyfold in DCM hearts when compared with normal heart tissue. In situ immunolabeling of MMP-1 indicated phenotypic differences in the fibroblast cells isolated from the DCM heart as compared to normal heart. These results suggest disruption in the balance of myopathic-fibroblast cell ECM-proteinase and antiproteinase in ECM remodeling which is followed by dilated cardiomyopathy.

Post-transcriptional regulation of extracellular matrix metalloproteinase in human heart end-stage failure secondary to ischemic cardiomyopathy.

Human heart matrix metalloproteinases (MMP) are present in the latent form and activated in the failing heart. To examine whether the MMP activation was due to gene and/or post-translational modification, we analysed tissue from 10 explanted hearts due to coronary heart disease (CHD) and five normal left atrial tissue from donor hearts. Based on in situ immunolabeling MMP-1, tissue inhibitor of metalloproteinase (TIMP-1) and collagen were co-localized in the interstitial tissue. Based on sandwich ELISA, TIMP-1 and MMP-1 levels were 37 +/- 8 ng/mg and 9 +/- 2 ng/mg in normal tissue (P < 0.01) and 12 +/- 5 ng/mg and 75 +/- 11 ng/mg in the infarcted tissue (P < 0.01), respectively. These levels suggest repression of TIMP-1 during myocardial infarction. Northern blot analysis indicated that the mRNAs for both MMP-1 and TIMP-1 were increased three-to four-fold in the infarcted tissue as compared to the normal tissue, suggesting upregulation of MMP and TIMP gene transcription following infarction. Based on in situ tissue overlay zymography, the generalized activation of MMP was observed in the interstitium of the infarcted heart. Zymographic and immunoblot analysis demonstrated the presence of one band at 66 kDa (MMP-2) in the normal tissue and several bands at 92 (MMP-9), 66 (MMP-2) and 54 kDa (MMP-1) in the infarcted heart. Incubation of the zymographic gel with metal chelator (phenanthroline) abolished bands at 92 kDa and 54 kDa but phenanthroline did not abolish the lytic band at 66 kDa. The 66 kDa band was completely abolished in the presence of phenanthroline and phenyl methyl sulfonyl fluoride (PMSF). 2D-zymographic analysis suggested that the lytic band at 66 kDa was a mixture of two neutral proteinases with different isoelectric point. Plasminogen/gelatin zymographic analysis of infarcted tissue extract indicated that the band at 66 kDa was plasmin generated due to increased expression of tissue plasminogen activator (tPA) activity. In relation to increased expression of gelatinase in the infarcted tissue, our data suggest that gelatinase B (92 kDa) is induced in diseased heart. The results suggest that tPA converts plasminogen to plasmin which, in turn, activates MMPs and inactivates TIMP-1 post-translationally following ischemic cardiomyopathy.

Induction of tissue inhibitor of metalloproteinase and its mitogenic response to endothelial cells in human atherosclerotic and restenotic lesions.

INTRODUCTION: Expression of extracellular matrix (ECM), including collagens and proteoglycans, is increased following atherosclerosis and restenosis. OBJECTIVE: To understand the Mechanism of ECM induction and accumulation, the balance among neutral matrix metalloproteinases (MMP), tissue inhibitor of metalloproteinase (TIMP) and activator (tissue plasminogen activator (tPA)) following atherosclerosis and restenosis was measured in human normal artery, and native atherosclerotic and restenotic lesions. DESIGN AND RESULTS: Based on zymographic analysis, a correlation between the increase in latent and intrinsic MMP activity and an increase in the duration from first angioplasty to restenotic atherectomy was found, suggesting decreased MMP activity from normal tissue to restenotic tissue. ELISA was carried out to measure the level of TIMP. Inhibition of collagenase activity, against fluorescein-conjugated type I collagen degradation, by normal, de novo and restenotic extracts was determined. TIMP levels were found to be increased in restenotic lesions (0.38+/-0.04 ng/mL) compared with normal arterial tissue (0.27+/-0.05 ng/mL) and with tissue derived from de novo (0.30+/-0.02 ng/mL atherosclerotic lesions. Mitogenic activity of tissue extracts, against normal human heart endothelial (HHE) cells, was measured using acid phosphatase assay as the marker of cell number. Based on neutralizing antibody to TIMP, mitogenic activity was observed in restenotic tissue to HHE cells. Using plasminogen/gelatin zymographic analysis, no significant change was observed in the level of tPA in extracts from all three groups (i.e., 8.1+/-1.2, 8.7+/-0.6, and 8.6+/-0.3 (arbitrary unit) in normal, de novo and restenotic tissue, respectively). CONCLUSIONS: These results suggest that accumulation of ECM in restenotic tissue following mechanical revascularization may in part be due to repression in MMP expression, and may be associated with increased level of TIMP and its mitogenic activity.

Extracellular matrix regulation of metalloproteinase and antiproteinase in human heart fibroblast cells.

Following myocardial infarction, extracellular matrix (ECM) is disrupted, which leads to the generation of collagen- and elastin-derived peptides (CDPs and EDPs, respectively). To investigate whether ECM-derived peptides (i.e., CDPs and EDPs) induce extracellular proteinases in human heart fibroblast (HHF) cells, we isolated CDP and EDP using gelfiltration and antibody affinity column chromatography. The CDP and EDP were characterized by their intrinsic fluorescence due to crosslink structure (pyridinoline and desmosine, respectively) and by immunoblot analysis using anti-desmosine antibody. Neutrophil elastase and cathepsin G were identified using selective chromogenic substrates and by their specific inhibition with alpha1-proteinase inhibitor and alpha1-antichymotrypsin, respectively. Elastase and cathepsin G were elevated in the infarcted tissue. Selective inhibition of matrix metalloproteinase (MMP) by a higher concentration of tetracycline or doxycycline in zymographic gels elicited an inhibition constant (IC50) of 278 +/- 10 microM and indicated that majority of MMP in the infarcted tissue is from fibroblast cells. The HHF proliferation was measured using an acid-phosphatase assay. The EDP and CDP induce HHF cell proliferation. After EDP treatment phenotypic (formation of pseudopodia) changes were observed in HHF cells. To measure whether phenotypic changes by EDP or CDP are associated with MMP and tissue inhibitor of metalloproteinase (TIMP) expression in HHF cells, we measured MMP and TIMP expression by zymographic and Northern blot (mRNA) analyses. The expression of MMP and TIMP were upregulated at both the protein and gene transcription levels. These results suggested that during ischemic cardiomyopathy, initially neutrophil proteinase activates latent myocardial MMP which can degrade ECM, which continuously degrades if not controlled by TIMP, leading to ventricular dilatation and dysfunction.

Matrix metalloproteinase activity expression in infarcted, noninfarcted and dilated cardiomyopathic human hearts.

In the normal myocardium matrix metalloproteinases (MMP) are present in the latent form. To examine whether MMP are activated following infarction or idiopathic dilated cardiomyopathy (DCM), we extracted and measured MMP activity in tissue derived from 7 explanted, failing human hearts due to either previous myocardial infarction (MI) or DCM. MMP activity in infarcted left ventricle (LV), noninfarcted LV and right ventricle (RV) from MI patients, as well as tissue from either ventricle of DCM patients, were compared to the activity of donor heart tissue. SDS-PAGE and dye-binding assays were used to determine total protein concentration, while collagenase activity was measured by SDS-PAGE type substrate gels embedded with type I gelatin (zymography). Accuracy of the zymographic technique was shown for tissue samples as small as 0.05 mg and was comparable to results obtained by a spectrophotometric method. After normalization for total protein concentration, we found 3 +/- 1% collagenase activity in normal atrial tissue which could be activated to 80-90% by trypsin or plasmin, indicating that collagenase is normally inactive or in a latent form in human heart. In endo- and epimyocardium of infarcted LV, on the other hand, collagenase activity was 85-95% and 10-20%, respectively, while 5-10% and 3-5%, respectively, in noninfarcted LV. In DCM, collagenolytic activity in the endo and epimyocardium was 75 +/- 5 and 35 +/- 5% in the LV and 35 +/- 7 and 20 +/- 5% in the RV, respectively. Thus, in dilated failing human hearts secondary to previous MI or DCM, MMP activity is increased. This is particularly the case within the endomyocardium of the infarcted and noninfarcted portions of either ventricle with MI and in both ventricles in DCM. This suggests that an activation of collagenase throughout the myocardium may contribute to its remodeling that includes ventricular dilatation and wall thinning.

Coronary vascular hyperpermeability and angiotensin II.

Elevations in plasma angiotensin II (AngII) are associated with evidence of vascular hyperpermeability expressed as efflux of plasma macromolecules into the perivascular and interstitial space. This exudative response is followed by a series of fibrogenic events that lead to a perivascular fibrosis of involved vessels. Mediators of hyperpermeability and fibrogenesis are unknown. In dogs receiving intravenous AngII, hemodynamic factors (i.e., arterial hypertension or coronary venoconstriction) were discounted as being responsible for the rise in cardiac lymph-to-plasma protein ratio. Accordingly, we investigated the relationship between AngII-induced coronary hyperpermeability and the release of prostaglandin E2 (PGE2) and activation of the basement membrane degrading matrix metalloproteinase, gelatinase/type IV collagenase. In dogs, cardiac lymph was monitored over the course of a 90-minute intravenous infusion of either AngII (0.2 to 0.3 micrograms/kg/min; n = 8) or saline solution (n = 6). Lymph was examined at 30-minute intervals for the following: total protein (Lowry's method), albumin (sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE)), plasma fibronectin (SDS-PAGE and enzyme-linked immunosorbent assay); PGE2 (radioimmunoassay) and gelatinase/type IV collagenase (zymography). In comparison with baseline we found a consistent rise in lymph flow (p = 0.02), total protein (p = 0.02), albumin, fibronectin, PGE2 (p = 0.03), and gelatinase/type IV collagenase (p = 0.019), which began after 30 minutes of AngII infusion. Similar trends were not observed in dogs receiving saline solution alone. We therefore conclude that AngII-induced coronary vascular hyperpermeability is associated with an early release of PGE2 and gelatinase.

Angiotensin-II-induced increase in transcoronary protein clearance: role of hypertension vs. nitric oxide or cyclo-oxygenase products.

Elevations in plasma angiotensin II (AngII) are associated with an efflux of plasma macromolecules into the perivascular and contiguous interstitial space. Whether this exudative response is related to associated hypertension or another effect of AngII is uncertain. We therefore monitored plasma and cardiac lymph total protein, albumin and fibronectin and calculated transvascular clearances for total protein (TVPC) and albumin (TVAC) and lymph fibronectin transport (LFT) every 30 min in open-chested, instrumented dogs. After baseline observations were obtained over 30 min, pressor (250 ng.kg.min-1) or nonpressor (11 ng.kg.min-1) doses of AngII were given intravenously for 90 min. Saline-treated, instrumented dogs served as controls. To address a potential secondary effect of AngII on vascular protein clearance, we monitored lymph prostaglandin E2 and cGMP (a marker of released nitric oxide, NO). At > or = 30 min, each dose of AngII was associated with a significant (P < or = 0.05) and comparable increase in TVPC, TVAC and LFT over baseline, indicating that increase in protein clearance was not related to elevated arterial pressure. Lymph cGMP rose significantly (P < or = 0.05) at 30 min for each dose of AngII and remained elevated thereafter. Lymph PGE2 was increased at > or = 60 min (P < or = 0.05) but only with the pressor dose. To determine the contribution of NO and PGE2 on AngII-induced transcoronary protein clearance, each dose of AngII was accompanied by co-administration of either the NO synthase inhibitor, NG-nitro-L-arginine methyl ester (L-NAME), or the cyclo-oxygenase inhibitor, indomethacin. L-NAME completely inhibited the release of cGMP and the increase in protein clearance was not seen. Indomethacin suppressed the release of PGE2, but did not prevent the increase in protein clearance. Thus, AngII-induced increase in transcoronary protein clearance is not related to arterial hypertension or the release of PGE2, but instead appears to be mediated by NO release.

Proteinases and restenosis in the human coronary artery: extracellular matrix production exceeds the expression of proteolytic activity.

To understand the balance of proteinase antiproteinase activity and the production of extracellular matrix (ECM) at the site of arterial injury, we analyzed the composition of ECM and proteinase activity in normal internal mammary arteries, tissue samples obtained from atherosclerotic coronary lesions and restenotic lesions obtained during directional coronary atherectomy. Histologically and biochemically, collagen and proteoglycans increased, and elastin decreased in samples from restenotic lesions when compared to samples taken from patients undergoing their first revascularization (de novo). In contrast, cellularity was increased in samples obtained from de novo patients as compared to samples obtained from restenotic lesions. Intrinsic activity of matrix metalloproteinases (MMPs) was measured by using zymography and scanning all the lytic bands in zymographic gel. In these gels, identical amounts of total protein were loaded in each lane. MMP activity was determined as % of the total (latent and active) MMPs after trypsin activation (100%) in the normal artery. Intrinsic MMP activity was reduced to 6% +/- 1% in atherosclerotic lesions and 1% +/- 1% in restenotic lesions, when compared to activity found in normal (10% +/- 3%) arteries. Based on solubilization of fluorescein-conjugated elastin by the extracts, the MMP-mediated elastinolytic activity was 0.2 +/- 0.1, 8.8 +/- 1.5, and 24.0 +/- 3 nmol/min/mg in restenotic, native atherosclerotic and normal tissue, respectively. The results suggested that, in arterial tissue from patients with angiographic restenosis, there is an increased production of ECM collagen and a decrease in MMP activity compared to both normal artery and atherosclerotic samples from de novo patients undergoing an initial revascularization procedure of a significant coronary artery lesion.

Evolving role of cardiopulmonary exercise testing in cardiovascular disease.

CPX testing allows for the objective assessment of aerobic capacity, anaerobic threshold, and the ventilatory response to exercise in patients with cardiovascular disease. These results can be used to assess severity of disease, its progression over time, prognosis, candidacy for transplantation, and response to therapy. CPX testing can also serve to distinguish cardiac from ventilatory causes of exertional dyspnea.

Stabilization of beta-ribbon structures in peptides using disulfide bonds.

The effect of a disulfide crosslink between two peptide chains on the stability of beta-ribbon secondary structures formed by these peptides has been investigated. Based on structural principles, we hypothesized that introduction of an unstrained disulfide crosslink at appropriate locations on two peptide chains should have a stabilizing effect on the beta-ribbon structure formed by these two peptide chains. To test this hypothesis, we designed and synthesized two sets of 9-residue peptides incorporating cysteine in one and (S)-alpha-amino-epsilon-mercaptohexanoic acid in the other. Comparison of the CD data clearly show that the dimer containing a disulfide bond between the longer sidechains of (S)-alpha-amino-epsilon-mercaptohexanoic acid shows dramatically higher beta-ribbon character as compared to the dimer with cystine disulfide bond, thus validating our structural hypothesis.

Immunostaining of cardiac biopsy specimens in the diagnosis of acute vascular (humoral) rejection: a control study.

The diagnosis of acute vascular (humoral) rejection in heart transplant biopsies is classically based on immunofluorescent studies of frozen tissue that show vascular staining for immunoglobulin and complement. We have noted that some pathologists have used immunostaining of formalin-fixed, paraffin-embedded tissue in testing for vascular rejection. To determine the specificity of immunostaining of heart biopsy specimens in the diagnosis of vascular rejection, we studied tissue from 68 consecutive endomyocardial biopsies from 16 patients without clinical or histologic evidence of vascular rejection. In each case, routinely processed formalin-fixed, paraffin-embedded tissue was stained for immunoglobulin G and immunoglobulin M with an avidin-biotin immunoperoxidase technique. Frozen tissue from each case was also stained for immunoglobulin G, immunoglobulin M, C3, and Clq by immunofluorescence. Immunoperoxidase stains on formalin-fixed tissue showed vascular staining for immunoglobulin in 67 of 68 (99%) of the cases. Staining was ablated if the antibodies were absorbed with their appropriate immunoglobulin. Immunofluorescent studies on frozen tissue showed no vascular staining for immunoglobulin or complement. We conclude that immunoperoxidase studies of routinely processed, formalin-fixed, paraffin-embedded tissues are nonspecific in the diagnosis of heart acute vascular rejection. The positive staining in fixed tissues may be due to labeling of passive immunoglobulins that are "fixed" in the vessels during routine processing but are washed away in techniques using frozen tissue.