Noman Ali

The role of angioplasty in patients with acute coronary syndrome and previous coronary artery bypass grafting

INTRODUCTION Angioplasty has changed the management of acute coronary syndrome (ACS). However, in patients with previous coronary artery bypass grafting (CABG), the role of angioplasty in the management of ACS is widely debated. Lack of clear guidelines leads to subjective and often stereotypical assessments based on clinician preferences. We sought to investigate if angioplasty affected all cause mortality in ACS patients with previous CABG. METHODS Completely anonymous information on patients with ACS with a background of previous CABG, co-morbidities and procedures attending three multi-ethnic general hospitals in the North West of England, United Kingdom in the period 2000-2012 was traced using the ACALM (Algorithm for Comorbidities, Associations, Length of stay and Mortality) study protocol using ICD-10 and OPCS-4 coding systems. Predictors of mortality and survival analyses were performed using SPSS version 20.0. RESULTS Out of 12,227 patients with ACS, there were 1172 (19.0%) cases of ACS in patients with previous coronary artery bypass grafting. Of these 83 (7.1%) patients underwent angioplasty. Multi-nominal logistic regression, accounting for differences in age and co-morbidities, revealed that having angioplasty conferred a 7.96 times improvement in mortality (2.36-26.83 95% CI) compared to not having angioplasty in this patient group. CONCLUSIONS We have shown that angioplasty confers significantly improved all cause mortality in the management of ACS in patients with previous CABG. The findings of this study highlight the need for clinicians to conscientiously think about the individual benefits and risks of angioplasty for every patient rather than confining to age related stereotypes.

Insulin- and growth factor-resistance impairs vascular regeneration in diabetes mellitus.

Diabetes and pre-diabetes are major contributors to cardiovascular mortality and morbidity. Insulin resistance is a key pathophysiological determinant of the metabolic and vascular abnormalities noted in these disorders. Ineffective vascular repair is likely to be an important contributor to the development of endothelial dysfunction, and subsequently atherosclerosis, in patients with diabetes. Beyond the systemic effects of the insulin resistant phenotype, including factors such as dysglycaemia and inflammation, cellular insulin resistance is emerging as an important factor in diabetic vascular disease. Disordered signal transduction via the PI3-kinase/Akt and MAP-kinase cascades is a hallmark of cellular insulin resistance, and such changes have been linked with both endothelial dysfunction and impaired angiogenesis. In this review we highlight the importance of insulin resistance to vascular repair and regeneration, discuss important cross-talk between the intracellular signalling of insulin and key pro-angiogenic molecules, and link these concepts to common patterns of vascular disease.

Correlation of Raman and photoluminescence spectra of electrochemically prepared n-type porous GaAs

Porous GaAs was formed by electrochemical etching of n-type GaAs wafers in HF- or HCl-based solution with different current densities. The porous structure formation has been confirmed by scanning electron microscopy and x-ray diffraction. The samples were subjected to Raman and photoluminescence (PL) spectroscopic investigations. Our results show that the spontaneous emission is originated from extremely small structures. As the porosity increases, there is an increase of the luminescent peak, lower energy shifting of the Raman feature, exhibiting broadening and decreased of first-order longitudinal optic mode peak intensity. In addition, the intensity of the transverse optic (TO) mode was highly enhanced and its peak was broadened due to the breakdown of the polarization selection rule in the case of high-porosity samples. Two new peaks around 200 and 233 cm−1 were observed, which were attributed to α-As and TO-Ga-As-a respectively. Both Raman and PL results were explained using quantum confinement models. There is reasonable agreement between the results obtained from PL and Raman spectroscopic investigations of the etched GaAs samples.

Ambulatory heart rate range predicts mode-specific mortality and hospitalisation in chronic heart failure

Objective We aimed to define the prognostic value of the heart rate range during a 24 h period in patients with chronic heart failure (CHF). Methods Prospective observational cohort study of 791 patients with CHF associated with left ventricular systolic dysfunction. Mode-specific mortality and hospitalisation were linked with ambulatory heart rate range (AHRR; calculated as maximum minus minimum heart rate using 24 h Holter monitor data, including paced and non-sinus complexes) in univariate and multivariate analyses. Findings were then corroborated in a validation cohort of 408 patients with CHF with preserved or reduced left ventricular ejection fraction. Results After a mean 4.1 years of follow-up, increasing AHRR was associated with reduced risk of all-cause, sudden, non-cardiovascular and progressive heart failure death in univariate analyses. After accounting for characteristics that differed between groups above and below median AHRR using multivariate analysis, AHRR remained strongly associated with all-cause mortality (HR 0.991/bpm increase in AHRR (95% CI 0.999 to 0.982); p=0.046). AHRR was not associated with the risk of any non-elective hospitalisation, but was associated with heart-failure-related hospitalisation. AHRR was modestly associated with the SD of normal-to-normal beats (R2=0.2; p<0.001) and with peak exercise-test heart rate (R2=0.33; p<0.001). Analysis of the validation cohort revealed AHRR to be associated with all-cause and mode-specific death as described in the derivation cohort. Conclusions AHRR is a novel and readily available prognosticator in patients with CHF, which may reflect autonomic tone and exercise capacity.

Formation of Porous GaAs by Pulsed Current Electrochemical Anodization: SEM, XRD, Raman, and Photoluminescence Studies

Porous GaAs (ir-GaAs) has been fabricated using pulsed current electrochemical etching. Scanning electron microscopy (SEM) shows that the time off (T off ) time on (T on ), and cycle time (T) can promote thicker and more uniform π-GaAs layers compared to those of direct current etching. Choosing suitable pulse parameters produces ir-GaAs layers with a thickness of 90 μm and crystallite size of 2.4 nm. X-ray diffraction (XRD) shows a high degree of crystallinity of the samples. Photoluminescence (PL) spectra showed two or three PL bands besides the PL band of the single-crystalline GaAs (c-GaAs). Peak PL wavelengths were located approximately at 362, 426, and 540 nm.

Synthesis, Structural, and Optical Properties of Electrochemically Deposited GeO2 on Porous Silicon

We present a method to synthesize submicrometer germanium dioxide (GeO2) on porous silicon (PS) by electrochemical deposition. The PS was electrochemically prepared in HF based electrolyte. GeCl4 was directly hydrolyzed by hydrogen peroxide to produce pure GeO2 and then electrochemically deposited on PS. The scanning electron microscopy results showed that the GeO2 structures are uniform in shape with diameter similar to 500 nm. The photoluminescence spectrum showed a prominent peak related to GeO2 at about 400 nm. The results indicated potential applications of GeO2 on the silicon based substrate for future optoelectronic nanodevices in the visible region using a simple fabrication method.

Pulse Current Electrochemical Deposition of Silicon for Porous Silicon Capping to Improve Hardness and Stability

This paper presents a method to improve the stability of porous silicon structures by electrochemical deposition of silicon capping.Porous silicon is formed by pulse electrochemical etching, followed by pulsed current electrochemical deposition, to provide auniform silicon capping layer on the porous structure. The capping layer thickness and hardness increase with deposition time. Thevariation of strain in the porous structure is also observed with varying silicon capping layer thickness. Silicon capping of 4 mwas sufficient to protect porous silicon from aging effects on their spontaneous emission, while a capping of 7.2 m causes a40 nm redshift on the spectrum.© 2008 The Electrochemical Society. DOI: 10.1149/1.3049861 All rights reserved.Manuscript submitted September 19, 2008; revised manuscript received November 12, 2008. Published December 23, 2008.

Study of Ge embedded inside porous silicon for potential MSM photodetector

Purpose – The purpose of this paper is to describe a very low‐cost way to prepare Ge nano/microstructures by means of filling the material inside porous silicon (PS) using a conventional and cost effective technique in which thermal evaporator with PS acts as patterned substrate. Also, the potential metal‐semiconductor‐metal (MSM) photodetector IV characteristics of the structure are demonstrated.Design/methodology/approach – PS was prepared by anodization of Si wafer in ethanoic hydrofluoric acid. The Ge layer was then deposited onto the PS by thermal evaporation. The process was completed by Ni metal deposition using thermal evaporator followed by metal annealing of 400°C for 10 min. Structural analysis of the samples was performed using energy dispersive X‐ray analysis (EDX), scanning electron microscope (SEM), X‐ray diffraction (XRD) and Raman spectroscopy.Findings – A uniform circular network distribution of pores is observed with sizes estimation of 100 nm to 2.5 μm by SEM. Also observed are cluster...

The role of angioplasty in octogenarian patients with Acute Coronary Syndrome.

a ACALM Study Unit in collaboration with Aston Medical School, School of Medical Sciences, Aston University, Birmingham, UK b Birmingham Medical School, Birmingham, UK c Royal Free London NHS Trust, London, UK d Department of Cardiology, Manchester Royal Infirmary, Manchester, UK e Division of Cardiology, University of Birmingham, Birmingham, UK f School of Medicine, Cardiff University, Cardiff, UK g Division of Cardiovascular and Diabetes Research, University of Leeds, Leeds, UK h Department of Acute Medicine, North Western Deanery, Manchester, UK

Insulinlike growth factor – binding protein-1 improves vascular endothelial repair in male mice in the setting of insulin resistance

Insulin resistance is associated with impaired endothelial regeneration in response to mechanical injury. We recently demonstrated that insulinlike growth factor-binding protein-1 (IGFBP1) ameliorated insulin resistance and increased nitric oxide generation in the endothelium. In this study, we hypothesized that IGFBP1 would improve endothelial regeneration and restore endothelial reparative functions in the setting of insulin resistance. In male mice heterozygous for deletion of insulin receptors, endothelial regeneration after femoral artery wire injury was enhanced by transgenic expression of human IGFBP1 (hIGFBP1). This was not explained by altered abundance of circulating myeloid angiogenic cells. Incubation of human endothelial cells with hIGFBP1 increased integrin expression and enhanced their ability to adhere to and repopulate denuded human saphenous vein ex vivo. In vitro, induction of insulin resistance by tumor necrosis factor α (TNFα) significantly inhibited endothelial cell migration and proliferation. Coincubation with hIGFBP1 restored endothelial migratory and proliferative capacity. At the molecular level, hIGFBP1 induced phosphorylation of focal adhesion kinase, activated RhoA and modulated TNFα-induced actin fiber anisotropy. Collectively, the effects of hIGFBP1 on endothelial cell responses and acceleration of endothelial regeneration in mice indicate that manipulating IGFBP1 could be exploited as a putative strategy to improve endothelial repair in the setting of insulin resistance.