A UK retrospective analysis of recurrent cardiovascular events following acute myocardial infarction in patients with multivessel disease and additional risk factors

Background

Patients with multivessel disease (MVD) are at increased risk of recurrent cardiovascular (CV) events in the early period after acute myocardial infarction (AMI) compared to patients without MVD, possibly due to increased atherosclerotic burden. Moreover, many have additional risk factors such as older age, peripheral artery disease (PAD), prior AMI or diabetes that could further increase risk of recurrent events. Real-world evidence regarding the impact of additional CV risk factors on outcomes in patients with MVD remains sparse.

Purpose

To assess clinical outcomes in the early period after AMI in a UK cohort of patients with MVD and additional risk factors.

Methods

A retrospective analysis (January 1, 2008–December 31, 2018, inclusive) was conducted using the Clinical Practice Research Datalink database linked to Hospital Episode Statistics and Office of National Statistics databases to identify patients with a confirmed diagnosis of MVD within the study period and at least one non-fatal myocardial infarction (MI) diagnosis code on or after their first recorded MVD diagnosis. The effect of diabetes on clinical outcomes was assessed by comparing patients diagnosed with diabetes on or prior to their index AMI with those with no concurrent diabetes diagnosis (MVD+DM and MVD-DM cohorts, respectively). Clinical outcomes were also assessed in AMI patients without diabetes but with at least two additional risk factors including: age >65 years, PAD diagnosis or prior MI diagnosis (MVD2RF+ cohort), and those with a single or none of the aforementioned risk factors (MVD2RF- cohort). Major adverse CV events (MACE) was defined as a composite of non-fatal AMI, non-fatal stroke or CV death.

Results

Of the 78,128 patients with MVD identified, 19,768 and 52,197 were eligible for inclusion in the MVD+DM and MVD-DM cohorts respectively. Occurrence of MACE was similar between the MVD+DM and MVD-DM cohorts at both 90 days (15% vs. 14%) and 1 year (19% vs. 17%) post-AMI; however, all-cause and CV mortality were significantly higher in the MVD+DM cohort over the study period (p<0.001). In the subset of patients without diabetes, 7,531 and 44,666 patients met the criteria for the MVD2RF+ and MVD2RF- cohorts, respectively. A substantially higher proportion of patients in the MVD2RF+ cohort experienced a MACE within 90 days or 1 year post-MI compared with the MVD2RF- cohort (90 days: 45% vs. 9%; 1 year: 56% vs. 11%), with non-fatal MI accounting for the majority of recurrent events. Kaplan-Meier survival analysis revealed that both all-cause and CV mortality were significantly higher in the MVD2RF+ than the MVD2RF- cohort (p<0.001).

Conclusions

Having multiple risk factors including older age, PAD and a history of AMI substantially increases the risk of recurrent events in patients with MVD, particularly in the early period after AMI. Strategies to reduce the systemic atherosclerotic burden and risk of recurrent events in these patients are needed.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): CSL Behring

Type-II superlattices base visible/extended short-wavelength infrared photodetectors with a bandstructure-engineered photo-generated carrier extractor

Visible/extended short-wavelength infrared photodetectors with a bandstructure-engineered photo-generated carrier extractor based on type-II InAs/AlSb/GaSb superlattices have been demonstrated. The photodetectors are designed to have a 100% cut-off wavelength of ~2.4 μm at 300K, with sensitivity down to visible wavelengths. The photodetectors exhibit room-temperature (300K) peak responsivity of 0.6 A/W at ~1.7 μm, corresponding to a quantum efficiency of 43% at zero bias under front-side illumination, without any anti-reflection coating where the visible cut-on wavelength of the devices is <0.5 µm. With a dark current density of 5.3 × 10-4 A/cm2 under -20 mV applied bias at 300K, the photodetectors exhibit a specific detectivity of 4.72 × 1010 cm·Hz1/2/W. At 150K, the photodetectors exhibit a dark current density of 1.8 × 10-10 A/cm2 and a quantum efficiency of 40%, resulting in a detectivity of 5.56 × 1013 cm·Hz1/2/W.

Recent progress of quantum cascade laser research from 3 to 12 μm at the Center for Quantum Devices [Invited]

The quantum cascade laser (QCL) is becoming the leading laser source in the mid-infrared (mid-IR) range, which contains two atmospheric transmission windows and many molecular fingerprint absorption features. Since its first demonstration in 1994, the QCL has undergone tremendous development in terms of the output power, wall plug efficiency, wavelength coverage, tunability and beam quality. At the Center for Quantum Devices, we have demonstrated high-power continuous wave operation of QCLs covering a wide wavelength range from 3 to 12 μm, with power output up to 5.1 W at room temperature. Recent research has resulted in power scaling in pulsed mode with up to 203 W output, electrically tunable QCLs based on monolithic sampled grating design, heterogeneous QCLs with a broad spectral gain, broadly tunable on-chip beam-combined QCLs, QCL-based mid-IR frequency combs, and fundamental mode surface emitting quantum cascade ring lasers. The developed QCLs will be the basis for a number of next-generation spectroscopy and sensing systems.

Nanoselective area growth of defect-free thick indium-rich InGaN nanostructures on sacrificial ZnO templates

Nanoselective area growth (NSAG) by metal organic vapor phase epitaxy of high-quality InGaN nanopyramids on GaN-coated ZnO/c-sapphire is reported. Nanopyramids grown on epitaxial low-temperature GaN-on-ZnO are uniform and appear to be single crystalline, as well as free of dislocations and V-pits. They are also indium-rich (with homogeneous 22% indium incorporation) and relatively thick (100 nm). These properties make them comparable to nanostructures grown on GaN and AlN/Si templates, in terms of crystallinity, quality, morphology, chemical composition and thickness. Moreover, the ability to selectively etch away the ZnO allows for the potential lift-off and transfer of the InGaN/GaN nanopyramids onto alternative substrates, e.g. cheaper and/or flexible. This technology offers an attractive alternative to NSAG on AlN/Si as a platform for the fabrication of high quality, thick and indium-rich InGaN monocrystals suitable for cheap, flexible and tunable light-emitting diodes.

Al(x)Ga(1-x)N-based deep-ultraviolet 320×256 focal plane array

We report the synthesis, fabrication, and testing of a 320×256 focal plane array (FPA) of back-illuminated, solar-blind, p-i-n, Al(x)Ga(1-x)N-based detectors, fully realized within our research laboratory. We implemented a pulse atomic layer deposition technique for the metalorganic chemical vapor deposition growth of thick, high-quality, crack-free, high Al composition Al(x)Ga(1-x)N layers. The FPA is hybridized to a matching ISC 9809 readout integrated circuit and operated in a SE-IR camera system. Solar-blind operation is observed throughout the array with peak detection occurring at wavelengths of 256 nm and lower, and falling off three orders of magnitude by ~285 nm. By developing an opaque masking technology, the visible response of the ROIC is significantly reduced; thus the need for external filtering to achieve solar- and visible-blind operation is eliminated. This allows the FPA to achieve high external quantum efficiency (EQE); at 254 nm, average pixels showed unbiased peak responsivity of 75 mA/W, which corresponds to an EQE of ~37%. Finally, the uniformity of the FPA and imaging properties are investigated.

Type-II superlattice dual-band LWIR imager with M-barrier and Fabry-Perot resonance

We report a high performance long-wavelength IR dual-band imager based on type-II superlattices with 100% cutoff wavelengths at 9.5 μm (blue channel) and 13 μm (red channel). Test pixels reveal background-limited behavior with specific detectivities as high as ~5×10¹¹ Jones at 7.9 μm in the blue channel and ~1×10¹¹ Jones at 10.2 μm in the red channel at 77 K. These performances were attributed to low dark currents thanks to the M-barrier and Fabry-Perot enhanced quantum efficiencies despite using thin 2 μm absorbing regions. In the imager, the high signal-to-noise ratio contributed to median noise equivalent temperature differences of ~20 milli-Kelvin for both channels with integration times on the order of 0.5 ms, making it suitable for high speed applications.

Effect of calcium or 25OH vitamin D3 dietary supplementation on bone loss at the hip in men and women over the age of 60

Dietary supplements that prevent bone loss at the hip and that can be applied safely in the elderly are likely to reduce hip fractures. A daily dietary supplement of 750 mg calcium or 15 microg 25OH vitamin D3 on bone loss at the hip and other sites, bone turnover and calcium-regulating hormones were studied over 4 yr in elderly volunteers using a randomized, double-blind, placebo-controlled trial. Bone mineral density (BMD) was measured by dual x-ray absorptiometry and bone structure by radiographs. Calcium biochemistry and bone turnover markers were measured in blood and urine. The 316 women entering the trial had a mean age of 73.7 yr and the 122 men of 75.9 yr. Baseline median calcium intake was 546 mg/day, and median serum 25OH vitamin D3 was 59 nmol/L. On placebo, loss of BMD at total hip was 2% and femoral medulla expansion was 3% over 4 yr. Calcium reduced bone loss, secondary hyperparathyroidism, and bone turnover. 25OH vitamin D3 was intermediate between placebo and calcium. Fracture rates and drop-out rates were similar among groups, and there were no serious adverse events with either supplement. A calcium supplement of 750 mg/day prevents loss of BMD, reduces femoral medullary expansion, secondary hyperparathyroidism, and high bone turnover. A supplement of 15 microg/day 25OH vitamin D3 is less effective, and because its effects are seen only at low calcium intakes, suggests that its beneficial effect is to reverse calcium insufficiency.

Effects of nitric oxide synthase inhibitors on bone formation in rats

NO is synthesized from L-arginine by at least three isoforms of nitric oxide synthase (NOS) and is known to function as a vasodilator and neurotransmitter. NO is produced by bone cells but its function in bone biology is, as yet, unclear. We hypothesized that NOS mediates bone formation in remodeling regions of the skeleton. We studied the effects of two NOS inhibitors: N(G)-nitro-L-arginine methyl ester (L-NAME), which is a general inhibitor of NOS activity and is known to inhibit the vasodilatory effects of the endothelial NOS (eNOS) isoform; and aminoguanidine, which is a selective inhibitor of the inducible NOS (iNOS) isoform. Our hypothesis was tested by treating rats with NOS inhibitors and measuring bone formation rates in the tibial epiphysis and diaphysis. Bone formation indices were measured using standard bone histomorphometry. L-NAME treatment significantly raised mean arterial blood pressure (MAP). This effect was partially reversed by addition of L-arginine. Aminoguanidine had no significant effect on MAP, indicating that it did not block eNOS. The treatments also had substantial effects on bone formation in remodeling trabecular bone. L-NAME did not significantly change trabecular bone formation rate, whereas aminoguanidine reduced bone formation rate in the tibial epiphysis by 79% compared with control. This reduction was completely reversed by L-arginine, suggesting that bone formation during remodeling is, in part, mediated through L-arginine metabolism. No effect of aminoguanidine on bone formation was seen in the tibial diaphysis, a site that undergoes minimal bone remodeling. This finding suggests that the L-arginine-NO pathway is important in bone remodeling.

Fluoride treatment increased serum IGF-1, bone turnover, and bone mass, but not bone strength, in rabbits

We hypothesized that fluoride partly acts by changing the levels of circulating calcium-regulating hormones and skeletal growth factors. The effects of oral fluoride on 24 female, Dutch-Belted, young adult rabbits were studied. The rabbits were divided into two study groups, one control and the other receiving about 16 mg fluoride/rabbit/day in their drinking water. After 6 months of fluoride dosing, all rabbits were euthanized and bone and blood samples were taken for analyses. Fluoride treatment increased serum and bone fluoride levels by over an order of magnitude (P < 0.001), but did not affect body weight or the following serum biochemical variables: urea, creatinine, phosphorus, total protein, albumin, bilirubin, SGOT, or total alkaline phosphatase. No skeletal fluorosis or osteomalacia was observed histologically, nor did fluoride affect serum PTH or Vitamin D metabolites (P > 0.4). BAP was increased 37% (P < 0.05) by fluoride; serum TRAP was increased 42% (P < 0.05); serum IGF-1 was increased 40% (P < 0.05). Fluoride increased the vertebral BV/TV by 35% (P < 0.05) and tibial ash weight by 10% (P < 0.05). However, the increases in bone mass and bone formation were not reflected in improved bone strength. Fluoride decreased bone strength by about 19% in the L5 vertebra (P < 0.01) and 25% in the femoral neck (P < 0. 05). X-ray diffraction showed altered mineral crystal thickness in fluoride-treated bones (P < 0.001), and there was a negative association between crystal width and fracture stress of the femur (P < 0.02). In conclusion, fluoride's effects on bone mass and bone turnover were not mediated by PTH. IGF-1 was increased by fluoride and was associated with increased bone turnover, but was not correlated with bone formation markers. High-dose fluoride treatment did not improve, but decreased, bone strength in rabbits, even in the absence of impaired mineralization.

Analysis of structure-function relationships in the platelet membrane glycoprotein Ib-binding domain of von Willebrand's factor by expression of deletion mutants

We have used a series of Escherichia coli-expressed deletion mutants of the glycoprotein (GP) Ib-binding domain of von Willebrand factor (vWF) to study the structural basis of its function. In addition to the prototypic molecule (rvWF441-733), we constructed 11 mutants; seven had deletions of sequence on the amino- and/or carboxyl-terminal side of the Cys509-Cys695 intrachain disulfide loop, and four had limited deletions inside the loop. Other cysteine residues in addition to 509 and 695, when present in the corresponding native sequence, were mutated to glycine; all molecules were purified in the oxidized as well as reduced and alkylated state. The smallest species retaining the ability to interact with GP Ib in the absence of modulators was the oxidized rvWF508-696; the latter, as well as rvWF441-696, became inactive after reduction and alkylation. In contrast, all the other fragments with deletions outside of the loop, but extending at least to residue 700, showed better binding to platelets after reduction and alkylation than when the Cys509-Cys695 disulfide bond was oxidized. Any limited deletion of sequence inside the loop caused complete loss of GP Ib-binding function both in the absence or in the presence of botrocetin, and this persisted even after reduction and alkylation. In contrast, all mutants with intact sequence between residues 509 and 695 bound to GP Ib in the presence of botrocetin, regardless of whether the 2 cysteine residues were oxidized or reduced and alkylated. Ristocetin, unlike botrocetin, appeared to have no effect in modulating the binding of any of the expressed fragments to platelets. Our findings suggest that the GP Ib-binding domain of vWF contains multiple interaction sites, but integrity of the sequence 509-695 is important for function.

Purification and characterization of an FSH releasing protein from porcine ovarian follicular fluid

A variety of hypophysiotropic peptides or proteins have been reported to be present in mammalian gonads. Inhibin, a hormone that under most circumstances selectively suppresses the secretion of follicle-stimulating hormone (FSH) but not luteinizing hormone (LH), has been isolated from the gonadal fluids of several species and characterized as a heterodimeric protein consisting of alpha- and beta-polypeptides associated by disulphide bonds. The complete amino-acid sequences of the precursors of porcine and human inhibin alpha-subunits and two distinct porcine inhibin beta-subunits (beta A and beta B) have been deduced from complementary DNA sequences. Gonadotropin releasing peptides have also been found in the gonad and have generally been shown to be active in radioreceptor assays for gonadotropin releasing hormone (GnRH) but to exhibit different chromatographic and immunological characteristics from those of GnRH. During our purification of inhibin from porcine follicular fluid, we noted fractions that could stimulate the secretion of FSH by cultured anterior pituitary cells. We report here the purification of an FSH releasing protein (FRP) and its characterization by SDS-polyacrylamide gel electrophoresis under non-reducing and reducing conditions and by partial sequence analysis. Our results indicate that porcine gonadal FRP is a homodimer consisting of two inhibin beta A-chains linked by disulphide bonds. FRP is highly potent (50% effective concentration (EC50) approximately 25 pM) in stimulating the secretion and biosynthesis of FSH but not of LH or any other pituitary hormone. In contrast to the effects of GnRH and other reported gonadal gonadotropin releasing fractions, the action of FRP is not mediated by GnRH receptors.

Bone and mineral status of patients beginning total parenteral nutrition

Total parenteral nutrition (TPN) is commonly used to provide nutrition in the seriously ill. Osteomalacia has been described with long-term TPN and the administered solutions and/or vitamin D metabolites have been blamed for the occurrence of osteomalacia. These studies however were performed on patients on long-term TPN programs. We in contrast measured the serum calcium (Ca), ionized calcium (Ca2+), phosphate (Pi), bone GLA protein (BGP), alkaline phosphatase (ALK-P), 25(OH)D, 1,25(OH)2D, the iPTH (carboxyl terminal) in 25 malnourished patients just beginning TPN therapy. The patients ranged from 25 to 80 yr of age and suffered from a variety of diseases. No patient had symptoms, recent fractures, or radiographic evidence of osteomalacia. The results of our study revealed significantly lower 25(OH)D (p less than 0.001), Pi (p less than 0.01), and Ca (p less than 0.01), but higher iPTH (p less than 0.002) values when compared to normals. BGP, 1,25(OH)2D and Ca2+ and ALK-P were not significantly different. We conclude that patients requiring TPN have low serum 25(OH)D values reflecting their nutritional status with a compensatory increase in PTH secretion to maintain their serum Ca2+ levels. The normal BGP levels may indicate depressed bone formation and skeletal resistance to PTH in the very ill patient. The cause of osteomalacia in these patients may therefore be multifactorial and not only related to the TPN infusions.

Purification and partial characterization of inhibin from porcine follicular fluid

Inhibin, a protein of gonadal origin that suppresses the basal secretion of follicle stimulating hormone by anterior pituitary cells has been purified from porcine follicular fluid. Using several RP-HPLC steps and gel filtration under denaturing conditions, we obtained a fraction approximately ten thousand fold purified which showed one band on SDS PAGE and in the same experiment two bands after reduction (MW ca 14K and ca 18K) suggesting a molecular weight of 32K for inhibin. Edman degradation of isolated inhibin and carboxymethylated chain A indicated that the first 6 residues were H-Ser-Thr-Ala-Pro-Leu-Pro-; by subtraction, the first 3 residues of chain B could be deduced to be H-Gly-Leu-Glu-. EC50 was ca 0.3 ng/ml or 10 pM in our in vitro pituitary cell culture assay. Antibodies to residues 1-6 were raised which could immunoneutralize purified inhibin activity in an in vitro assay.

Reversed-phase high-performance liquid chromatography: preparative purification of synthetic peptides

Biologically active peptides synthesized by the solid phase methodology of Merrifield were purified by reversed-phase high-performance liquid chromatography using newly developed preparative radially compressed cartridges fitting Waters Assoc . Prep LC 500 liquid chromatograph. Cartridges were handpacked with Vydac C18, C4 or diphenyl derivatized silicas (pore size 300 A) of different particle sizes (10-20 micron). Large scale purification of gram amounts of gonadotropin releasing hormone analogs (agonist and antagonist) as well as amidated human pancreatic tumor growth hormone releasing factor (a 40-peptide) illustrate the resolutive power of this technique applied to the isolation of more than 300 synthetic peptides in our laboratory over the last two years. Difficult separations were achieved by changing supports (C18, C4, diphenyl) as well as mobile phase composition: (triethylammonium phosphate pH 2.25 or 6.5, 0.1% trifluoroacetic acid, ammonium acetate pH 6.5 and acetonitrile). Protected amino acids and peptides amenable to normal-phase chromatography on Vydac spherical underivatized silica were purified economically by the reversed-phase mode. It is understood that this general, convenient and versatile strategy may be applicable to the preparative scale isolation of any other class of compounds usually separated on reversed-phase high-performance liquid chromatography.

Differences in serum bone GLA protein with age and sex

Serum bone Gla protein (BGP) was measured by radioimmunoassay in 166 healthy men and women aged 30-90 years. Serum BGP levels increased with age in both sexes and were higher in women than in men at all ages. The most striking rise occurred in women after age 40-49. BGP was significantly correlated positively with serum alkaline phosphatase and negatively with midshaft and distal bone mass in both sexes. In women only, BGP levels were significantly positively related to levels of immunoreactive parathyroid hormone (iPTH). When age was included in the multiple regression analysis BGP was still correlated with alkaline phosphatase in both sexes and iPTH in women only. Serum BGP levels were significantly higher in 13 osteoporotic patients than in age-matched controls. It is postulated that with increasing age 1,25-dihydroxyvitamin D levels fall, causing a rise in iPTH and thus in bone turnover, which is reflected by a rise in BGP levels.

Demonstration that cyclic adenosine 3',5'-monophosphate mediates the lipolytic action of parathyroid hormone

Studies were carried out with rat epididymal fat pads first to compare the effects of the synthetic N-terminal 1-34 peptide of bovine parathyroid hormone and of the native hormone to determine whether this portion of the molecule is responsible for the lipolytic action of the hormone and second to determine whether this biologic action of parathyroid hormone is mediated by cyclic adenosine 3',5'-monophosphate. The N-terminal polypeptide was as effective as the native hormone in stimulating lipolysis in the concentration range between 10(-8) M and 10(-6) M. Parathyroid hormone stimulated lipolysis by isolated fat cells. The concentration of cyclic adenosine 3',5'-monophosphate in the fat pads was significantly increased by the hormone (10(-6)M). Lipolytic stimulation by parathyroid hormone (10(-6)M) was diminished by insulin (100 muU/ml) and prostaglandin E1 (1 mug/ml), both of which are known inhibitors of lipolysis. The findings indicate that the amino-terminal 1-34 peptide portion of parathyroid hormone is responsible for the lipolytic action and that this effect is mediated through cyclic adenosine 3',5'-monophosphate.

Determination of the total carbon dioxide outputs of rats by the D2O18 method

The doubly-labeled water (D2O18) method for measuring CO2 output has been tested in eight rats by comparing the value obtained by this procedure with the total CO2 actually collected. The average absolute discrepancy between the two values was 3 (±3)%, and the average discrepancy when account was taken of algebraic sign was +2 (±4)%. (The values in parentheses are standard deviations of the distributions.)