Citations

Background— Revascularization strategies often hinge on the presence and degree of left anterior descending coronary artery (LAD) stenosis. A decision for bypass surgery is often based on the durability of surgical LAD revascularization compared with percutaneous approaches. By decreasing restenosis, drug-eluting stents may have reduced the “reintervention gap” between surgery and percutaneous intervention, making the percutaneous route preferable. Methods and Results— Of the 1101 patients in the SIRIUS trial, 459 with an LAD stenosis were randomized to percutaneous intervention with either sirolimus-eluting or bare-metal stents. Baseline demographic, clinical, and angiographic data were obtained. Patients had 1-year clinical and 8-month angiographic follow-up. Baseline characteristics were similar in both groups. The majority of lesions were tubular type B lesions (69.7%) with a mean diameter of 2.73 mm and a mean length of 14.0 mm. The binary in-stent restenosis rate was 2% for the sirolimus stent group and 41.6% for the bare-metal arm (relative risk, 0.05; 95% CI, 0.02 to 0.1; P <0.001). One-year major adverse events (defined as cardiac death, Q-wave and non–Q-wave myocardial infarction, or target vessel revascularization) was decreased 59% in the sirolimus-stent group (9.8% versus 24.9%; relative risk, 0.39; 95% CI, 0.26 to 0.61; P <0.001). Subgroup analysis of 135 patients with proximal LAD lesions showed similar benefits. In-stent restenosis was 0 in the proximal LAD sirolimus-eluting group (n=67), compared with 38% in the bare-metal arm (n=68), and major adverse events demonstrated a similar trend, with a 50% decrease compared with control patients (10.4% versus 20.6%, P =NS). Conclusions— Sirolimus-eluting stents significantly decrease revascularization rates in LAD lesions. At 1 year, sirolimus-eluting stent revascularization rates are comparable to historic single vessel bypass surgery revascularization rates.

Background— Electron-beam computed tomography (EBCT) is used to measure coronary calcification but not for aortic valve calcification (AVC). Its accuracy, association with aortic stenosis (AS) severity, and diagnostic and prognostic value with respect to AVC are unknown. Methods and Results— In 30 explanted aortic valves, the AVC score by EBCT (1125±1294 Agatston units [AU]) showed a strong linear correlation ( r =0.96, P <0.0001) with valvular calcium weight (653±748 mg) by pathology that allowed estimation of calcium weight as AVC score/1.7, with a small standard error of the estimate (53 mg). In 100 consecutive clinical patients, we measured AVC by EBCT and AS severity by echocardiographic aortic valve area (AVA). The AVC score was 1316±1749 AU (range 0 to 7226 AU). Intraobserver and interobserver variabilities were excellent (4±4% and 4±10%, respectively). AVC and AVA were strongly associated ( r =0.79, P <0.0001) but had a curvilinear relationship that suggested that AVC and AVA provide complementary information. AVC score ≥1100 AU provided 93% sensitivity and 82% specificity for diagnosis of severe AS (AVA <1 cm 2 ), with a receiver operator characteristic curve area of 0.89. AVC assessment by echocardiography was often more severe than by EBCT ( P <0.0001). During follow-up, 22 patients either died, developed heart failure, or required surgery. With adjustment for age, sex, symptoms, ejection fraction, and AVA, the AVC score was independently predictive of event-free survival (risk ratio 1.06 per 100-AU increment [1.02 to 1.10], P <0.001), even after adjustment for echocardiographic calcifications. Conclusions— AVC is accurately and reproducibly measured by EBCT and shows a strong association and diagnostic value for severe AS. The curvilinear relationship between AVC and AVA suggests these measures are complementary, and indeed, AVC provides independent outcome information. Thus, AVC is an important measurement in the evaluation of patients with AS.

Abstract Background: Transthyretin-associated hereditary amyloidosis (ATTR) is an inherited disease in which variants in the primary structure of transthyretin (TTR; prealbumin) lead to the extracellular polymerization of insoluble protein fibrils, causing organ failure and ultimately death when major organs are involved. We have developed an integrated approach to molecular diagnosis with initial analysis of intact plasma TTR by electrospray ionization mass spectrometry (MS) and referral of positive samples for DNA sequence analysis and real-time PCR to confirm the common Gly6Ser polymorphism. Methods: Samples from 6 patients previously diagnosed with ATTR and from 25 controls with (n = 15) or without (n = 10) polyneuropathy were analyzed in a blinded fashion for the presence of variant TTR. TTR protein was extracted with an immunoaffinity resin from 20 μL of archived plasma samples. The purified TTR was reduced with tris(2-carboxyethyl)phosphine and analyzed by MS. The appearance of two peaks (or a single peak shifted in mass indicative of a homozygous variant), including the wild-type mass of 13 761 Da, was indicative of the presence of a variant, and the individual was referred for DNA sequence analysis. Results: MS analysis of intact reduced TTR correctly identified each of six samples known to contain variant TTR. These results were corroborated by subsequent DNA sequence analysis. Additionally, all Gly6Ser polymorphisms were correctly called based on the +30 mass shift and an equal relative abundance of the +30 polymorphism relative to wild-type TTR. No false-positive results were seen. Conclusions: This referral method eliminates the necessity of sequencing most samples and allows screening for the familial forms of amyloidosis in a broad patient population in a timely fashion. This method correctly identified all previously known variants and also identified a novel variant, Val94Ala.

Collagen-induced arthritis (CIA) is an animal model of autoimmune inflammatory polyarthritis that has features similar to rheumatoid arthritis (RA). Much like RA, susceptibility to mouse CIA is influenced by the major histocompatibility complex (MHC), H-2, and restricted to the H-2q and H-2r haplotypes. Whereas the role of the H-2A molecule in susceptibility to CIA is well established, little is known about the role of H-2E molecule in the disease. In this study, we analyzed the effect of a transgenic E beta d molecule on CIA susceptibility in a recombinant mouse B10.RQB3, which expresses the CIA susceptible Aq genes and an Eak gene, but does not produce an E molecule since Ebq is nonfunctional. In the presence of an Ebd transgene, a viable E molecule is generated. Whereas B10.RQB3 were susceptible to CIA, B10.RQB3-E beta d+ showed a dramatic reduction in the incidence of arthritis as well as a decrease in the level of anti-mouse and anti-bovine CII antibodies in their serum. No clear cut differences in the expression of T cell receptor (TCR) V beta was observed between E beta d+ and E beta d- transgenic mice. Mechanisms underlying the protective effect of E beta d transgenic molecule on CIA may shed light on how HLA-DR molecules influence human RA.

HLA-B27 transgenic mice in the context of various H-2 haplotypes were produced. A high expression of the HLA-B27 antigen was observed in mice homozygous for H-2b, H-2f, H-2s, H-2p, H-2r, and H-2k haplotypes. Mice of the H-2v haplotype expressed HLA-B27 at an intermediate level. Expression of HLA-B27 was minimal in mice of the H-2q and H-2d haplotypes. This was observed both on the B10 background and in DBA/2 or BALB/c mice. Only minimal expression of HLA-B27 could be detected in B10.PL (KuDd) or B10.RKDB (KkSkDdLb) mice, indicating that the low level of HLA-B27 expression maps to the H-2D gene or a very closely linked gene. Integration and transcription of the HLA-B27 gene does not appear to be different between high-expressing haplotypes and low-expressing haplotypes as determined by Southern and Northern blot analysis. However, expression of HLA-B27 on the cell surface correlated with the amount of HLA-B27 and beta 2M that could be immunoprecipitated with an anti-B27 antibody. Therefore, the association of the B27 heavy chain with endogenous beta 2M and subsequent expression on the cell surface are disrupted in mice with some class I H-2D genes. Possible mechanisms that might contribute to this defect in assembly, transport, and expression of class I molecules are discussed.

We have found cell surface expression of an E alpha molecule in recombinant and transgenic mouse strains lacking an E beta molecule. Flow cytometry has shown low level expression of E alpha in B10.RQB3 (I-AqEk alpha) and B10.RFB2 (I-AfEk alpha) mice. We have also found that B10.Q (H-2q) mice can express the Ek alpha transgene. Since these strains do not have functional E beta chains, we propose that the E alpha A beta hybrid dimers are formed in low numbers and can be picked up by FACS analysis. So far we have not been able to identify these hybrid molecules by cytotoxicity or immunoprecipitation. The E alpha/A beta molecule can function in vivo during thymic selection in the clonal deletion of two V beta TCR subsets, V beta 11 and V beta 6, which have been shown to interact with the intact I-E molecule.

We have identified an inbred strain of mouse, RIII S/J (H-2r), that has the largest known deletion of the TCR V beta genes by screening with mAb and TCR V beta specific probes. Upon screening of PBL with mAb F23.1, which is specific for V beta 8 TCR, RIII S/J was found to be negative. On further screening with mAb KJ 23a, which is specific for V beta 17a TCR, RIII S/J was completely negative. We next tested RIII S/J with mAb 44-22-1, which is specific for V beta 6 TCR, and found it also to be negative. The (B10 X RIII)F1 mice showed a 50% expression of V beta 6 gene, indicating a genomic rather than a clonal deletion. mAb KJ25, detecting V beta 3, was positive in RIII S/J, denoting the downstream boundary for the deletion. Southern blot analysis of liver DNA using TCR V beta-specific probes confirmed the deletion of V beta 8 gene subfamily and V beta 5 gene subfamily, along with V beta 9, V beta 11, V beta 12, and V beta 13 genes similar to the known TCR V beta deletion mutants (SWR, SJL, C57L, and C57Br). In addition, RIII S/J is missing V beta 6, V beta 15, and V beta 17 genes. Our mapping of the deletion indicates that RIII S/J has lost approximately 130 kb of V beta chromosome and with it 13 V beta genes out of the known 21 V beta genes of the TCR. The deletion is marked by the presence of V beta 10 gene upstream and V beta 3 gene downstream.

Arthritis was induced by immunization of type II collagen in adjuvant in mice from H-2q-bearing crosses between SWR (H-2q/q) and B10 (H-2b/b mice), two strains known to be resistant to collagen-induced arthritis (CIA). The resistance of B10 is known to be due to its MHC haplotype, but it was postulated that the resistance of SWR mice which expresses the susceptible MHC haplotype could be due to the deletion of close to 50% of the V beta genes of the T cell receptor (TCR) in them. 17% of the F1 hybrids, 33% of the SWR backcrosses, 68% of the B10 backcrosses, and 52% of the F2 hybrids developed arthritis on follow-up to 5 mo after primary immunization with collagen. There was no significant difference in anti-type II collagen antibody titers between the arthritic and nonarthritic mice in each of these crosses. The segregation of the TCR genes with arthritis was determined in the F2 population by typing with F23.1 mAb that reacts with T cells using V beta 8 subfamily genes in their TCRs. SWR mice are F23.1- as V beta 8 genes are deleted in them. All six of arthritic mice homozygous for H-2q, and thus with an H-2 haplotype similar to SWR mice, expressed the F23.1 marker. These studies indicate that for complete susceptibility to collagen-induced arthritis, not only is a susceptible MHC haplotype (H-2q) important, but possibly also the presence of a subset of T cells using certain specific V beta genes in their TCRs. Other background genes may, however, modulate the severity of arthritis.