Endothelialisation of an autologous pericardial valve implanted in the aortic position.
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Aged↗
Biomedical subjects
R Pillai
Publications and source records attributed to R Pillai.
A distinct strategy to generate high-affinity peptide binders to receptor tyrosine kinases.
We describe a novel and general way of generating high affinity peptide (HAP) binders to receptor tyrosine kinases (RTKs), using a multi-step process comprising phage-display selection, identification of peptide pairs suitable for hetero-dimerization (non-competitive and synergistic) and chemical synthesis of heterodimers. Using this strategy, we generated HAPs with K(D)s below 1 nM for VEGF receptor-2 (VEGFR-2) and c-Met. VEGFR-2 HAPs bound significantly better (6- to 500-fold) than either of the individual peptides that were used for heterodimer synthesis. Most significantly, HAPs were much better (150- to 800-fold) competitors than monomers of the natural ligand (VEGF) in various competitive binding and functional assays. In addition, we also found the binding of HAPs to be less sensitive to serum than their component peptides. We believe that this method may be applied to any protein for generating high affinity peptide (HAP) binders.
Dimerization↗
Comparison of different isolation techniques prior gene expression profiling of blood derived cells: impact on physiological responses, on overall expression and the role of different cell types.
Owing to its clinical accessibility, peripheral blood is probably the best source for the assessment of differences or changes in gene expression associated with disease or drug response and therapy. Gene expression patterns in peripheral blood cells greatly depend on temporal and interindividual variations. However, technical aspects of blood sampling, isolation of cellular components, RNA isolation techniques and clinical aspects such as time to analysis and temperature during processing have been suggested to affect gene expression patterns. We therefore assessed gene expression patterns in peripheral blood from 29 healthy individuals by using Affymetrix microarrays. When RNA isolation was delayed for 20-24 h-a typical situation in clinical studies-gene signatures related to hypoxia were observed, and downregulation of genes associated with metabolism, cell cycle or apoptosis became dominant preventing the assessment of gene signatures of interindividual variation. Similarly, gene expression patterns were strongly dependent on choice of cell and RNA isolation and preparation techniques. We conclude that for large clinical studies, it is crucial to reduce maximally the time to RNA isolation. Furthermore, prior to study initiation, the cell type of interest should already be defined. Our data therefore will help to optimize clinical studies applying gene expression analysis of peripheral blood to exploit drug responses and to better understand changes associated with disease.
Adult↗
Analysis of the mouse transcriptome based on functional annotation of 60,770 full-length cDNAs.
Only a small proportion of the mouse genome is transcribed into mature messenger RNA transcripts. There is an international collaborative effort to identify all full-length mRNA transcripts from the mouse, and to ensure that each is represented in a physical collection of clones. Here we report the manual annotation of 60,770 full-length mouse complementary DNA sequences. These are clustered into 33,409 'transcriptional units', contributing 90.1% of a newly established mouse transcriptome database. Of these transcriptional units, 4,258 are new protein-coding and 11,665 are new non-coding messages, indicating that non-coding RNA is a major component of the transcriptome. 41% of all transcriptional units showed evidence of alternative splicing. In protein-coding transcripts, 79% of splice variations altered the protein product. Whole-transcriptome analyses resulted in the identification of 2,431 sense-antisense pairs. The present work, completely supported by physical clones, provides the most comprehensive survey of a mammalian transcriptome so far, and is a valuable resource for functional genomics.
Alternative Splicing↗
Relationship between the G894T polymorphism (Glu298Asp variant) in endothelial nitric oxide synthase and nitric oxide-mediated endothelial function in human atherosclerosis.
Nitric oxide (NO), produced by endothelial nitric oxide synthase (eNOS), plays important roles in normal vascular homeostasis, and reduced endothelial NO bioactivity is an important feature of vascular disease states. The Glu298Asp (G894T) polymorphic variant of eNOS has been associated with vascular disease, but functional data are lacking. Accordingly, we examined the relationships between NO-mediated endothelial function, the presence of the eNOS Glu298Asp variant, and clinical risk factors for atherosclerosis. Endothelium-dependent vasorelaxations to different agonists were determined in human saphenous veins obtained from patients with coronary artery disease and identified risk factors (n = 104). Patients were genotyped for the eNOS G894T polymorphism. Nitric oxide-mediated endothelial vasorelaxations were highly variable between patients. Reduced vasorelaxations were associated with increased number of clinical risk factors for atherosclerosis (r = - 0.54, P < 0.001), whereas the Glu298Asp variant was not associated with any differences in contractions to phenylephrine, NO-mediated vasorelaxations to acetylcholine, bradykinin or calcium ionophore, or relaxations to the NO donor sodium nitroprusside. Increased atherosclerotic risk factors, but not the presence of the eNOS Glu298Asp variant, are associated with impaired nitric oxide-mediated endothelial vasomotor function, suggesting that this polymorphism does not have a major direct functional effect on vascular eNOS activity in human atherosclerosis.
Aged↗
Minimally invasive saphenous vein harvesting: effects on endothelial and smooth muscle function.
BACKGROUND: The long saphenous vein remains the commonest conduit used in coronary artery bypass grafting procedures. Surgical trauma during vein harvesting can cause endothelial and smooth muscle injury that has important implications for vein graft longevity. Minimally invasive vein harvesting is advocated to reduce wound morbidity. However, the functional consequences of increased handling and traction, with potentially detrimental effects, remain unknown. METHODS: Forty patients were prospectively randomized into either a minimally invasive (minimal) or traditional (open) saphenous vein harvest group. Smooth muscle contractile function was assessed by responses to potassium chloride and phenylephrine. Endothelial cell function was assessed by responses to serial escalations in concentration of acetylcholine, bradykinin, calcium ionophore, sodium nitroprusside, and N-nitro-L-arginine using isometric tension studies. RESULTS: Harvest times were similar for both groups. The total incision length in the minimal group was significantly shorter than in the open group. There were no differences in smooth muscle contractions to either receptor-independent or receptor-mediated agonists between the two groups. Similarly, vasorelaxation in response to both endothelium-dependent and endothelium-independent agonists were similar in both groups. CONCLUSIONS: Minimally invasive saphenous vein harvesting is associated with similar medial smooth muscle and endothelial function as open harvesting. These findings suggest that minimally invasive harvesting techniques can be used without major detrimental effects on vascular integrity.
Aged↗
Minimally invasive vein harvest and wound healing using the SaphLITE Retractor System.
BACKGROUND: In response to reported wound complication rates of 19% to 43% for traditional saphenous vein harvest, several minimally invasive vein harvest (MIVH) techniques have been developed. The purpose of this investigation is to determine the effectiveness of one such MIVH technology, the Genzyme SaphLITE Retractor System (Genzyme Biosurgery, Cambridge, MA). METHODS: Since May 2000, saphenectomy was undertaken in 305 coronary artery bypass graft (CABG) patients using SaphLITE in a prospective, nonrandomized trial at three centers. Patients were assessed for wound healing (ASEPSIS tool) and incisional pain (numeric scale) through the postoperative visit. Harvest times, incision lengths, and vein lengths were recorded. RESULTS: ASEPSIS indicated satisfactory healing in 96.0%. Infection rate was 1.3% with four patients requiring antibiotics and debridement of one incision. Of hospitalized patients, 85.4% had no or minimal affected leg pain. Additional mean data include: harvest time 43.4 +/- 17.6 minutes, incision number 3.0 +/- 1.2, incision length 2.9 +/- 1.4 cm, and vein length 46.0 +/- 15.2 cm. CONCLUSIONS: SaphLITE provides an effective alternative to traditional saphenous vein harvest, with improved wound healing, decreased pain, and acceptable harvest times.
Adult↗
A multiprotein complex mediates the ATP-dependent assembly of spliceosomal U snRNPs.
The spliceosomal snRNPs U1, U2, U4 and U5 contain a common RNP structure termed the Sm core that is formed by the binding of Sm proteins onto the U snRNA. Although isolated Sm proteins assemble spontaneously onto U snRNAs in vitro, there is increasing evidence that SMN and its interactor Gemin2 are involved in this process in vivo. Here, we describe a cell-free assay system for the assembly of U snRNPs that closely reproduces in vivo conditions. Using this system, we show that assembly of U1 snRNP depends on ATP. Immunodepletion of SMN-Gemin2 from the extract abolished assembly even though the extract contained high levels of Sm proteins. An affinity-purified macromolecular SMN complex consisting of 16 components including all Sm proteins restored assembly in the immunodepleted extract. These data provide the first direct evidence that a complex containing SMN and Gemin2 mediates the active assembly of spliceosomal U snRNPs.
Adenosine Triphosphate↗
Release of hydrocortisone from a cream matrix: dependency of release on suspension concentration and measurement of solubility and diffusivity.
The principal object of the present research was to investigate the sensitivity of drug release from a semisolid system to the manner of its preparation and to the concentration of drug placed within it. Established theory indicated that release should be concentration dependent, with the specific dependency determined by whether the drug in the system is fully in solution or is present substantially as suspended matter. To purposefully explore these relatively untested performance expectations, the total amount of drug in the formula was varied from a low concentration of 0.25% to a high concentration of 3%. Conditions were established such that drug release conformed to release from a semi-infinite medium into a receptor sink. At every concentration, release profiles were well reproduced in replicate samples and, where multiple lots of a kind were employed, from lot to identical lot. In all cases square root of time release kinetics were observed. Moreover and without exception, the square root of time release rate from run to run was directly proportional to the square root of the total concentration of hydrocortisone placed in the formulations. The amount released per square root of time per square root of total concentration was nearly identical from run to run irrespective of total concentration. The overall behavior fit theoretical expectations for suspensions having only a small fraction of the drug they contain in solution. That this condition prevailed even at the lowest 0.25% hydrocortisone strength was proven by independently measuring hydrocortisone's solubility (0.02%). Measurement of solubility permitted estimation of the effective diffusivity of the drug through the cream (2 x 10(-7) cm2/s).
Administration, Cutaneous↗
Performance of Edwards prima stentless aortic valve over eight years.
Long-term clinical and hemodynamic performance is a key consideration in using a stentless aortic bioprosthesis. This study reports clinical and hemodynamic performance of Prima stentless aortic valve during our 8-year follow-up. In the study, 85 patients underwent aortic valve replacement (Edwards Prima or Prima plus stentless valve) and had follow-up at discharge and then annually up to 8 years. The mean age at operation was 72 +/- 5 yrs, 49 were male and 25% underwent concomitant CABG. Doppler Echo studies were performed to determine mean pressure gradient (mPG), effective orifice area (EOA) and the degree of regurgitation of stentless valves. Aortic root geometry was assessed by the ratio of sinotubular junction to valve size at peak systole. Patient survival rate was 82% +/- 5% at 5th year and 72% +/- 6% at 8th year. The freedom from valve structure failure was 97% +/- 2% at 5th and 8th year. Valve mPG and EOA at 8 years remained significantly better than those at discharge (6.8 +/- 4.4 mm Hg v 9.7 +/- 6.2 mm Hg; 1.91 +/- 0.54 cm(2) v 1.63 +/- 0.71 cm(2), both P <.01), and did not differ from those at 3-year follow-up. Mean sinotubular junction diameter remained below valve size (0.96 +/- 0.14). Mild degree of valvular regurgitation was present in 17% of patients, but this did not progress over the period of follow-up. After aortic valve replacement with the Prima stentless valves, excellent valve hemodynamics and normal root geometry were well maintained up to 8 years, but longer-term follow-up of a larger cohort remains essential.
Aged↗
Functional effect of the C242T polymorphism in the NAD(P)H oxidase p22phox gene on vascular superoxide production in atherosclerosis.
BACKGROUND: Increased superoxide anion production increases oxidative stress and reduces nitric oxide bioactivity in vascular disease states. NAD(P)H oxidase is an important source of superoxide in human blood vessels, and some studies suggest a possible association between polymorphisms in the NAD(P)H oxidase CYBA gene and atherosclerosis; however, no functional data address this hypothesis. We examined the relationships between the CYBA C242T polymorphism and direct measurements of superoxide production in human blood vessels. METHODS AND RESULTS: Vascular NAD(P)H oxidase activity was determined in human saphenous veins obtained from 110 patients with coronary artery disease and identified risk factors. Immunoblotting, reverse-transcription polymerase chain reaction, and DNA sequencing showed that p22phox protein, mRNA, and 242C/T allelic variants are expressed in human blood vessels. Vascular superoxide production, both basal and NADH-stimulated, was highly variable between patients, but the presence of the CYBA 242T allele was associated with significantly reduced vascular NAD(P)H oxidase activity, independent of other clinical risk factors for atherosclerosis. CONCLUSIONS: Association of the CYBA 242T allele with reduced NAD(P)H oxidase activity in human blood vessels suggests that genetic variation in NAD(P)H oxidase components may play a significant role in modulating superoxide production in human atherosclerosis.
Aged↗
Successful emergency coronary surgery for intractable ventricular fibrillation without prior angiography.
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Adult↗
UltraRapid communications : vascular superoxide production by NAD(P)H OxidaseAssociation with endothelial dysfunction and clinical risk factors
Superoxide anion plays important roles in vascular disease states. Increased superoxide production contributes to reduced nitric oxide (NO) bioactivity and endothelial dysfunction in experimental models of vascular disease. We measured superoxide production by NAD(P)H oxidase in human blood vessels and examined the relationships between NAD(P)H oxidase activity, NO-mediated endothelial function, and clinical risk factors for atherosclerosis. Endothelium-dependent vasorelaxations and direct measurements of vascular superoxide production were determined in human saphenous veins obtained from 133 patients with coronary artery disease and identified risk factors. The predominant source of vascular superoxide production was an NAD(P)H-dependent oxidase. Increased vascular NAD(P)H oxidase activity was associated with reduced NO-mediated vasorelaxation. Furthermore, reduced endothelial vasorelaxations and increased vascular NAD(P)H oxidase activity were both associated with increased clinical risk factors for atherosclerosis. Diabetes and hypercholesterolemia were independently associated with increased NADH-dependent superoxide production. The association of increased vascular NAD(P)H oxidase activity with endothelial dysfunction and with clinical risk factors suggests an important role for NAD(P)H oxidase-mediated superoxide production in human atherosclerosis. The full text of this article is available at http://www.circresaha.org. Key Words:atherosclerosis endothelium superoxide nitric oxide diabetes Two Distinct Congenital Arrhythmias Evoked by a Multidysfunctional Na(+) Channel Marieke W. Veldkamp, Prakash C. Viswanathan, Connie Bezzina, Antonius Baartscheer, Arthur A.M. Wilde, Jeffrey R. Balser Abstract-The congenital long-QT syndrome (LQT3) and the Brugada syndrome are distinct, life-threatening rhythm disorders linked to autosomal dominant mutations in SCN5A, the gene encoding the human cardiac Na(+) channel. It is believed that these two syndromes result from opposite molecular effects: LQT3 mutations induce a gain of function, whereas Brugada syndrome mutations reduce Na(+) channel function. Paradoxically, an inherited C-terminal SCN5A mutation causes affected individuals to manifest electrocardiographic features of both syndromes: QT-interval prolongation (LQT3) at slow heart rates and distinctive ST-segment elevations (Brugada syndrome) with exercise. In the present study, we show that the insertion of the amino acid 1795insD has opposite effects on two distinct kinetic components of Na(+) channel gating (fast and slow inactivation) that render unique, simultaneous effects on cardiac excitability. The mutation disrupts fast inactivation, causing sustained Na(+) current throughout the action potential plateau and prolonging cardiac repolarization at slow heart rates. At the same time, 1795insD augments slow inactivation, delaying recovery of Na(+) channel availability between stimuli and reducing the Na(+) current at rapid heart rates. Our findings reveal a novel molecular mechanism for the Brugada syndrome and identify a new dual mechanism whereby single SCN5A mutations may evoke multiple cardiac arrhythmia syndromes by influencing diverse components of Na(+) channel gating function. The full text of this article is available at http://www.circresaha.org. Key Words: Na(+) channel inactivation long-QT syndrome Brugada syndrome
Journal Article↗
Vascular superoxide production by NAD(P)H oxidase: association with endothelial dysfunction and clinical risk factors.
Superoxide anion plays important roles in vascular disease states. Increased superoxide production contributes to reduced nitric oxide (NO) bioactivity and endothelial dysfunction in experimental models of vascular disease. We measured superoxide production by NAD(P)H oxidase in human blood vessels and examined the relationships between NAD(P)H oxidase activity, NO-mediated endothelial function, and clinical risk factors for atherosclerosis. Endothelium-dependent vasorelaxations and direct measurements of vascular superoxide production were determined in human saphenous veins obtained from 133 patients with coronary artery disease and identified risk factors. The predominant source of vascular superoxide production was an NAD(P)H-dependent oxidase. Increased vascular NAD(P)H oxidase activity was associated with reduced NO-mediated vasorelaxation. Furthermore, reduced endothelial vasorelaxations and increased vascular NAD(P)H oxidase activity were both associated with increased clinical risk factors for atherosclerosis. Diabetes and hypercholesterolemia were independently associated with increased NADH-dependent superoxide production. The association of increased vascular NAD(P)H oxidase activity with endothelial dysfunction and with clinical risk factors suggests an important role for NAD(P)H oxidase-mediated superoxide production in human atherosclerosis. The full text of this article is available at http://www.circresaha.org.
Acetylcholine↗
Thyroid function screening in acute geropsychiatric admissions.
Thyroid function abnormalities have been associated with psychiatric illness. Even though it is a common practice to assess thyroid function in geropsychiatric patients, a literature search for the past 10 years did not reveal any published studies of assessments of thyroid function abnormalities in acute geropsychiatric populations. A retrospective chart review of 197 acute geropsychiatric inpatients and 14 comparison group patients showed that 40 geropsychiatric patients and 2 comparison group patients had abnormal thyroid function tests (TFfs). The most common abnormality was elevated triiodothyronine uptake (T3U), which was noted in 19 female and 13 male geropsychiatric patients. The difference in the prevalence of TFT abnormalities between the geropsychiatric patients and the comparison group subjects was not statistically significant. Both T3U and free thyroxine index (FTI) were significantly higher in the female geropsychiatric patients than in the female comparison group patients. The abnormalities in T3U and FTI in this study group may be related to an increased prevalence of unidentified systemic illness or to the presence of chronically poor nutrition.
Aged↗
The Ultracor tilting disc heart valve prosthesis in the aortic position: mid-term follow up.
BACKGROUND AND AIM OF THE STUDY: The Ultracor valve is a recent introduction in the evolution of the tilting disc valve. This report summarizes a single surgeon's experience with the valve in the aortic position over a nine-year period. METHODS: Between 1990 and 1999, 94 patients received an Ultracor heart valve prosthesis in the aortic position. Forty-five patients (48%) had associated procedures, of which 32 (34%) were coronary artery grafts. Mean follow up was 2.6 years; total follow up was 229 patient-years. Follow up was 100% complete. RESULTS: The actuarial survival rate, including operative mortality rate, at five years was 82%. Actuarial freedom from valve-related death was 96% at five years. The linearized complication rate was 1.7%/year for late valve-related mortality, 1.7%/year for thromboembolism, 2.2%/year for anticoagulant-related hemorrhage (ACH), 1.3%/year for prosthetic valve endocarditis (PVE), and 1.7%/year for reoperation. The estimates of actuarial freedom from complications at five years were thromboembolism 89%, ACH 90%, PVE 96% and reoperation 96%. No structural failure or valve thrombosis was observed. CONCLUSION: Our experience over nine years showed the Ultracor heart valve prosthesis in the aortic position to be comparable with other currently evaluated mechanical heart valves in terms of durability and clinical results. Further study in this area should concentrate on the impact of valve type on left ventricular recovery post-implantation to provide additional information to the surgeon when selecting a valve from the plethora of choices available.
Adult↗
Medium-term determinants of left ventricular mass index after stentless aortic valve replacement.
BACKGROUND: This study aimed to investigate the risk factors for elevated left ventricular mass index 3 to 5 years after stentless aortic valve replacement, and to elucidate the underlying physiologic mechanisms. METHODS: Eighty-nine patients (age, 76 +/- 6 years, 51 males) having a stentless porcine valve for aortic stenosis (n = 76) or regurgitation (n = 13) were prospectively studied by Doppler echocardiography 3 to 5 years after operation. Left ventricular systolic function, mass index, blood pressure, cardiac rhythm, and New York Heart Association function class were all determined. Stentless valve effective orifice area, mean pressure drop, and the presence and degree of aortic regurgitation were quantified. RESULTS: The mean stentless aortic valve size was 24 +/- 2 mm. At follow-up time of 45 +/- 9 months, effective orifice area index was 1.2 +/- 0.35 cm2 x m(-2), and mean pressure drop was 5.7 +/- 3.8 mm Hg. Left ventricular mass index was 128 +/- 47 g x m(-2), and ejection fraction was 63% +/- 14%. Multivariant analysis showed a greater left ventricular mass index to be associated with nonsinus rhythm (versus sinus) (163 +/- 8 versus 131 +/- 7 g x m(-2)), greater pulse pressure (> 84 mm Hg) (161 +/- 7 versus 133 +/- 7 g x m(-2)), New York Heart Association class II or III (versus class I) (166 +/- 10 versus 128 +/- 5 g x m(-2)), and male sex (versus female) (160 +/- 7 versus 134 +/- 8 g x m(-2)), all p < 0.01. Mean pressure drop (> 8 mm Hg), effective orifice area index (< 1.0 cm2 x m(-2)), the presence of mild regurgitation of the stentless valve, or the type of previous valve disease were insignificant determinants of left ventricular mass index. CONCLUSIONS: Three to five years after the implantation, stentless aortic valve hemodynamics remain excellent. Left ventricular hypertrophy caused by previous native aortic valve disease had largely regressed. However, patient-related factors, particularly systemic blood pressure, cardiac rhythm, and function, are significant causes of late residual left ventricular hypertrophy. Thus, continued medical care and earlier surgical intervention may further improve the outlook for these patients.
Aged↗
Serum S100B and hypothermic circulatory arrest in adults.
BACKGROUND: Cerebral injury is the most important complication of cardiac operations with cardiopulmonary bypass. Prolonged total circulatory arrest (TCA) can expose patients to an even greater risk of cerebral injury. We sought to detect the degree of cerebral injury in adults who had thoracic aortic operations with TCA by measuring S100B protein, which is released into the circulation after cerebral injury. METHODS: Serial measurements of S100B protein, a highly specific serum marker of astroglial damage, were performed in 26 patients who had complex aortic operations, of whom 13 required cardiopulmonary bypass alone (for aortic root replacement), and in 13 patients who required an additional period of TCA (for type A aortic dissections and arch aneurysms). Blood samples were taken preoperatively, at skin closure, and 5 and 24 hours postoperatively. RESULTS: There were significant increases in serum S100B concentrations in all patients, and peak levels occurred at skin closure. The magnitude of the increase in S100B was significantly greater at all postoperative time points and persisted longer in the TCA group. There was a significant correlation between the duration of the TCA and S100B concentration at 5 hours (r = 0.66, p = 0.01) and 24 hours (r = 0.63, p = 0.02) postoperatively. CONCLUSIONS: S100B levels were higher in all patients who had complex aortic operations and were significantly greater in patients requiring a period of TCA. The duration of the TCA period correlated with S100B levels 5 hours and at 24 hours postoperatively. Circumstantial evidence, in accordance with other studies, suggests that S100B protein is a marker for cerebral injury during cardiac operations.
Adult↗