The utility of human two plus one small pronucleated zygotes (2.1PN) based on clinical outcomes and the focused ploidy analysis

PURPOSE

Are human embryos arising from two plus one small pronucleated zygotes, called 2.1 pronuclei (PN), clinically useful?

METHODS

In a retrospective embryo cohort study and prospective experimental study, a total of 287 cycles in which at least one 2.1PN was identified in the fertilization check were included. Embryonic development and clinical outcome were compared for the 1395 2PN zygotes and 304 2.1PN zygotes that were siblings. All embryos were individually cultured in time-lapse systems. Twenty-five 2.1PN-derived blastocysts, donated for research, were used in focused single-nucleotide variant ploidy analysis to identify the distribution pattern of heterozygosity.

RESULTS

The average diameter of PN was 24.9 ± 2.4 µm for large PN and 10.2 ± 2.4 µm for small PN; 79.9% of small PN was derived from female pronuclei. Blastocyst formation rate and good-quality blastocyst rate were significantly lower with 2.1PN embryos than with 2PN embryos (40.0% vs. 57.7%, 21.4% vs. 33.5%, respectively). A total of 13 embryos derived from 2.1PN were transferred, and three healthy babies were born. In ploidy constitutions of trophectoderm (TE), 2.1PN-derived blastocyst TE was shown to be mostly diploid (95.8%, 23/24), and only one blastocyst showed triploid.

CONCLUSIONS

It was suggested that 2.1PN embryos have lower embryonic developmental potential than 2PN embryos, but most of the 2.1PN were diploid, indicating that they are likely to be clinically usable. It is recommended to perform embryo transfer following a combination of PGT-A and ploidy analysis.

Vaginal Microbiota and Pregnancy Outcomes of Patients with Conization Histories

Background: One of the major risks of preterm birth is a history of conization. However, the risk of infection due to this procedure is still not well known. Using next-generation sequencing, we aimed to reveal the influence of conization on vaginal microbiota in the following pregnancy, and their relationship between spontaneous preterm birth (sPTB). Methods: We conducted a prospective cohort study including 133 pregnant patients, of whom 25 had conization histories and 108 did not. Vaginal microbiome samples were collected using swabs by an obstetrician upon inclusion in the first trimester and during delivery. V1-V2 of the 16S rRNA gene were amplified and analyzed to identify the bacteria. Results: The conization group had a significantly lower delivery week (34 weeks vs. 36 weeks, p = 0.003) and higher sPTB rate (64% vs. 8.3%, p ≤ 0.001) than the control group. In the conization group, alpha (Chao 1, p = 0.02; phylogenetic diversity whole tree, p = 0.04) and beta diversity (permutational multivariate analysis of variance test, p = 0.04) of the vaginal microbiota was significantly higher during delivery in patients who delivered preterm than in those who delivered term. Community-state type IV in the first trimester was significantly associated with sPTB (overall odds ratio 3.80, 95% confidence interval 1.33-10.8, p = 0.01). Conclusions: Conization is a risk factor for sPTB. Increased risk of sPTB in patients after conization may belong to the vulnerable defense mechanism, due to the shortened cervix and decreased cervical mucus.

Endometrial and vaginal microbiomes influence assisted reproductive technology outcomes

OBJECTIVE

The role of Lactobacillus-dominant microbiota in the endometrium in reproductive function is unclear. We therefore aimed to explore the impact of the balance of Lactobacillus and pathological bacteria in the endometrial and vaginal microbiomes on the pregnancy outcomes of women treated with assisted reproductive technology (ART).

METHODS

This study included 35 women with infertility submitted to good-quality embryo transfers. The cutoff values for abundance of Lactobacillus species (spp.) and pathological bacteria in the endometrium and vagina were calculated. Women with Lactobacillus spp. and pathological bacteria abundance above the cutoff values were categorized in the high-abundance group, whereas those with abundance below cutoff values were categorized in the low abundance group. We divided the patients into four groups based on the combination of high/low abundance of Lactobacillus spp. and pathological bacteria.

RESULTS

The 35 cases of good-quality embryo transfer resulted in 21 pregnancies. Pregnant women were present in significantly higher proportions in the high Lactobacillus spp. abundance and low pathological bacteria abundance group, whereas the opposite combination (i.e., low Lactobacillus spp. abundance and high pathological bacteria abundance) saw a significantly higher proportion of nonpregnant women (p=0.022).

CONCLUSIONS

The balance between Lactobacillus and pathological bacterial abundance in the endometrial and vaginal microbiomes is associated with pregnancy from ART.

Microbiome analysis in women with endometriosis: Does a microbiome exist in peritoneal fluid and ovarian cystic fluid?

Purpose

To investigate the relationship between the microbiome of the female genital tract and endometriosis.

Methods

This prospective cohort study included 36 women who underwent laparoscopic surgery for ovarian tumor from July 2019 to April 2020. Of them, 18 had endometriosis, and 18 did not have endometriosis. Vaginal secretions, endometrial fluid, peritoneal fluid, and ovarian cystic fluid were collected during surgery. Next‐generation sequencing of bacterial 16S rRNA was performed to characterize the microbiome.

Results

Specific microbiomes were not detected in either peritoneal fluid or ovarian cystic fluid regardless of the presence or absence of endometriosis and the type of cyst. When the cutoff value of infectious bacterial abundance in the vagina was set as 64.3%, there were many cases more than a cutoff value in the endometriosis group significantly (p = 0.01). When the cutoff value of infectious bacterial abundance in the endometrium was set as 18.6%, there were many cases more than a cutoff level in the endometriosis cases significantly (p = 0.02).

Conclusion

Peritoneal fluid and ovarian cystic fluid are almost sterile, although dysbiosis may occur in the vaginal and endometrial microbiome in women with endometriosis.

Next-generation sequencing of 16S rRNA for identification of invasive bacterial pathogens in a formalin-fixed paraffin-embedded placental specimen: a case report of perinatal fulminant Streptococcus pyogenes infection

Intrauterine infection is one of the most important causes of maternal death. In perinatal emergency, we often miss an opportunity to obtain culture specimens. In this study, we tried to examine whether we investigated whether bacteria causing infection can be detected from a formalin-fixed paraffin-embedded (FFPE) placental specimen. We examined the placenta from a maternal invasive infection that resulted in infectious abortion at 18 weeks of gestation. The case was diagnosed by acute fever and abdominal pain, and the patient was cured after 3 weeks of intensive antimicrobial treatment. Four Streptococcus pyogenes strains were isolated from vaginal fluid and blood cultures of the patient. All of the strain types were emm1/ST28. We amplified the V1-V2 region of 16S rRNA from an FFPE placental specimen and sequencing was performed using a next-generation sequencer (NGS). Taxonomic analysis was then performed for sequenced data. We succeeded in detecting causative pathogens from the FFPE placenta: 69.1% of the predominantly identified bacteria were S. pyogenes and other small populations of bacteria were detected. Our results revealed the utility of NGS for 16S rRNA analysis of an FFPE placenta. This method may reveal previous perinatal invasive infections of unknown origin retrospectively.

Genome-wide association study of epilepsy in a Japanese population identified an associated region at chromosome 12q24

OBJECTIVE

Although a number of genes responsible for epilepsy have been identified through Mendelian genetic approaches, and genome-wide association studies (GWASs) have implicated several susceptibility loci, the role of ethnic-specific markers remains to be fully explored. We aimed to identify novel genetic associations with epilepsy in a Japanese population.

METHODS

We conducted a GWAS on 1825 patients with a variety of epilepsies and 7975 control individuals. Expression quantitative trait locus (eQTL) analysis of epilepsy-associated single nucleotide polymorphisms (SNPs) was performed using Japanese eQTL data.

RESULTS

We identified a novel region, which is ~2 Mb (lead SNP rs149212747, p = 8.57 × 10^-10 ), at chromosome 12q24 as a risk for epilepsy. Most of these loci were polymorphic in East Asian populations including Japanese, but monomorphic in the European population. This region harbors 24 transcripts including genes expressed in the brain such as CUX2, ATXN2, BRAP, ALDH2, ERP29, TRAFD1, HECTD4, RPL6, PTPN11, and RPH3A. The eQTL analysis revealed that the associated SNPs are also correlated to differential expression of genes at 12q24.

SIGNIFICANCE

These findings suggest that a gene or genes in the CUX2-RPH3A ~2-Mb region contribute to the pathology of epilepsy in the Japanese population.

16S rRNA long-read nanopore sequencing is feasible and reliable for endometrial microbiome analysis

RESEARCH QUESTION

Full-length 16S rRNA gene sequencing using nanopore technology is a fast alternative to conventional short-read 16S rRNA gene sequencing with low initial investment costs that has been used for various microbiome studies but has not yet been investigated as an alternative approach for endometrial microbiome analysis. Is in-situ 16S rRNA gene long-read sequencing using portable nanopore sequencing technology feasible and reliable for endometrial microbiome analysis?

DESIGN

A prospective experimental study based on 33 patients seeking infertility treatment between January and October 2019. A 16S rRNA gene long-read nanopore sequencing protocol for analysing endometrial microbiome samples was established, including negative controls for contamination evaluation and positive controls for bias evaluation. Contamination caused by kit and exterior sources was identified and excluded from the analysis. Endometrial samples from 33 infertile patients were sequenced using the optimized long-read nanopore sequencing protocol and compared with conventional short-read sequencing carried out by external laboratories.

RESULTS

Of the 33 endometrial patient samples, 23 successfully amplified (69.7%) and their microbiome was assessed using nanopore sequencing. Of those 23 samples, 14 (60.9%) were Lactobacillus-dominated (>80% of reads mapping to Lactobacillus), with 10 samples resulting in more than 90% Lactobacillus reads. Our long-read nanopore sequencing revealed results similar to two conventional short-read sequencing approaches and to long-read sequencing validation carried out in external laboratories.

CONCLUSION

In this pilot study, 16S rRNA gene long-read nanopore sequencing was established to analyse the endometrial microbiome in situ that could be widely applied owing to its cost efficiency and portable character.

Prevalence and Spectrum of Pathogenic Germline Variants in Japanese Patients With Early-Onset Colorectal, Breast, and Prostate Cancer

PUPOSE

We investigated the prevalence and spectrum of pathogenic germline variants in patients with early-onset colorectal cancer (CRC), breast cancer (BC), and prostate cancer (PCA) in the Japanese population. We also identified pathogenic variants in other cancer risk genes, giving consideration to future multigene testing panels for this population.

METHODS

We performed whole-genome sequencing for 1,037 Japanese individuals, including patients with early-onset CRC (n = 196), BC (n = 237), and PCA (n = 215) and controls (n = 389). We screened for pathogenic variants, including single nucleotide variants and copy number variants, among well-established first-tier cancer genes for each cancer type and examined an expended second-tier panel including cancer-predisposing genes from the Cancer Gene Census.

RESULTS

Proportions of patients with germline pathogenic variants differed by cancer subgroup, with the highest in BC (14.8%), followed by CRC (9.2%), and PCA (3.7%). In contrast, 2 of 389 control subjects (0.5%) carried a germline pathogenic variant. In comparison with controls, the proportion of patients with pathogenic variants in the second-tier panel was increased significantly for PCA (3.7% to 11.6%, P = 2.96 × 10^-4), but not for CRC or BC, after multitesting adjustment. In patients with PCA, DNA repair pathway genes in the extended panel often contained pathogenic variants (P = .011).

CONCLUSION

Our analyses support the clinical usefulness of established cancer gene panels in the Japanese population for 3 major cancer types. Additional genes, especially those involved in DNA repair, might be considered for developing multipanel testing in Japanese patients with early-onset PCA.

Tuberculosis infection and lung adenocarcinoma: Mendelian randomization and pathway analysis of genome-wide association study data from never-smoking Asian women

We investigated whether genetic susceptibility to tuberculosis (TB) influences lung adenocarcinoma development among never-smokers using TB genome-wide association study (GWAS) results within the Female Lung Cancer Consortium in Asia. Pathway analysis with the adaptive rank truncated product method was used to assess the association between a TB-related gene-set and lung adenocarcinoma using GWAS data from 5512 lung adenocarcinoma cases and 6277 controls. The gene-set consisted of 31 genes containing known/suggestive associations with genetic variants from previous TB-GWAS. Subsequently, we followed-up with Mendelian Randomization to evaluate the association between TB and lung adenocarcinoma using three genome-wide significant variants from previous TB-GWAS in East Asians. The TB-related gene-set was associated with lung adenocarcinoma (p = 0.016). Additionally, the Mendelian Randomization showed an association between TB and lung adenocarcinoma (OR = 1.31, 95% CI: 1.03, 1.66, p = 0.027). Our findings support TB as a causal risk factor for lung cancer development among never-smoking Asian women.

Genome-wide association study suggests four variants influencing outcomes with ranibizumab therapy in exudative age-related macular degeneration

To identify factors associated with ranibizumab responses in patients with exudative age-related macular degeneration (AMD), we performed a genome-wide association study (GWAS) and a replication study using a total of 919 exudative AMD patients treated with intravitreal ranibizumab in a Japanese population. In the combined analysis of GWAS and the replication study, no loci reached genome-wide significant level; however, we found four variants showed suggestive level of associations with visual loss at month three (rs17822656, rs76150532, rs17296444, and rs75165563: P_combined < 1.0 × 10^-5). Of the candidate genes within these loci, three were relevant to VEGF-related pathway (KCNMA1, SOCS2, and OTX2). The proportions of patients who worsened visual acuity were 13.7%, 38.8%, 58.0%, and 80.0% in patients with 0, 1, 2, and 3 or more identified risk variants, respectively. Changes in visual acuity decreased linearly as the number of risk variants increased (P = 1.67 × 10^-12). The area under the curve using age, baseline visual acuity, and history of previous treatment was 0.607, and improved significantly to 0.713 in combination with identified variants (P < 0.0001). Although further study is needed to confirm their associations, our results offer candidate variants influencing response to ranibizumab therapy.

A genome-wide association study identifies two novel susceptibility loci and trans population polygenicity associated with bipolar disorder

Genome-wide association studies (GWASs) have identified several susceptibility loci for bipolar disorder (BD) and shown that the genetic architecture of BD can be explained by polygenicity, with numerous variants contributing to BD. In the present GWAS (Phase I/II), which included 2964 BD and 61 887 control subjects from the Japanese population, we detected a novel susceptibility locus at 11q12.2 (rs28456, P=6.4 × 10-9), a region known to contain regulatory genes for plasma lipid levels (FADS1/2/3). A subsequent meta-analysis of Phase I/II and the Psychiatric GWAS Consortium for BD (PGC-BD) identified another novel BD gene, NFIX (Pbest=5.8 × 10-10), and supported three regions previously implicated in BD susceptibility: MAD1L1 (Pbest=1.9 × 10-9), TRANK1 (Pbest=2.1 × 10-9) and ODZ4 (Pbest=3.3 × 10-9). Polygenicity of BD within Japanese and trans-European-Japanese populations was assessed with risk profile score analysis. We detected higher scores in BD cases both within (Phase I/II) and across populations (Phase I/II and PGC-BD). These were defined by (1) Phase II as discovery and Phase I as target, or vice versa (for 'within Japanese comparisons', Pbest~10-29, R2~2%), and (2) European PGC-BD as discovery and Japanese BD (Phase I/II) as target (for 'trans-European-Japanese comparison,' Pbest~10-13, R2~0.27%). This 'trans population' effect was supported by estimation of the genetic correlation using the effect size based on each population (liability estimates~0.7). These results indicate that (1) two novel and three previously implicated loci are significantly associated with BD and that (2) BD 'risk' effect are shared between Japanese and European populations.

Abstract B25: Association of variations in HLA-class II and other loci with susceptibility to EGFR-mutated lung adenocarcinoma

Background: Lung adenocarcinoma (LADC) driven by somatic EGFR mutations is more prevalent in East Asians (30-50%) than in European/Americans (10-20%). Understanding the genetic factors underlying such LADC is required to elucidate disease etiology and to identify effective methods of prevention.

Methods: We investigate genetic factors underlying the risk of this disease by conducting a genome-wide association study, followed by two validation studies, in 3,173 Japanese patients with EGFR mutation-positive lung adenocarcinoma and 15,158 controls.

Results: Four loci, 5p15.33 (TERT), 6p21.3 (BTNL2, HLA-class II), 3q28 (TP63) and 17q24.2 (BPTF), previously shown to be strongly associated with overall lung adenocarcinoma risk in East Asians, were re-discovered as loci associated with a higher susceptibility to EGFR mutation-positive.

Citation Format: Kouya Shiraishi, Yukinori Okada, Atsushi Takahashi, Yoichiro Kamatani, Kyota Ashikawa, Yukihide Momozawa, Hideo Kunitoh, Shingo Matsumoto, Atsushi Takano, Kimihiro Shimizu, Akiteru Goto, Koji Tsuta, Shun-ichi Watanabe, Yuichiro Ohe, Yukio Watanabe, Yasishi Goto, Hiroshi Nokihara, Koh Furuta, Akihiko Yoshida, Koichi Goto, Tomoyuki Hishida, Masahiro Tsuboi, Katsuya Tsuchihara, Yohei Miyagi, Haruhiko Nakamura, Tomoyuki Yokose, Katsuya Tanaka, Toshiteru Nagashima, Yoichi Ohtaki, Daichi Maeda, Kazuhiro Imai, Yoshihiro Minamiya, Hiromi Sakamoto, Akira Saito, Yoko Shimada, Kuniko Sunami, Motonobu Saito, Teruhiko Yoshida, Jun Yokota, Fumihiko Matsuda, Keitaro Matsuo, Yataro Daigo, Michiaki Kubo, Takashi Kohno. Association of variations in HLA-class II and other loci with susceptibility to EGFR-mutated lung adenocarcinoma. [abstract]. In: Proceedings of the AACR Special Conference: Improving Cancer Risk Prediction for Prevention and Early Detection; Nov 16-19, 2016; Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2017;26(5 Suppl):Abstract nr B25.

Association between GWAS-identified lung adenocarcinoma susceptibility loci and EGFR mutations in never-smoking Asian women, and comparison with findings from Western populations

To evaluate associations by EGFR mutation status for lung adenocarcinoma risk among never-smoking Asian women, we conducted a meta-analysis of 11 loci previously identified in genome-wide association studies (GWAS). Genotyping in an additional 10,780 never-smoking cases and 10,938 never-smoking controls from Asia confirmed associations with eight known single nucleotide polymorphisms (SNPs). Two new signals were observed at genome-wide significance (P < 5 × 10-8), namely, rs7216064 (17q24.3, BPTF), for overall lung adenocarcinoma risk, and rs3817963 (6p21.3, BTNL2) which is specific to cases with EGFR mutations. In further sub-analyses by EGFR status, rs9387478 (ROS1/DCBLD1) and rs2179920 (HLA-DPB1) showed stronger estimated associations in EGFR-positive compared to EGFR-negative cases. Comparison of the overall associations with published results in Western populations revealed that the majority of these findings were distinct, underscoring the importance of distinct contributing factors for smoking and non-smoking lung cancer. Our results extend the catalogue of regions associated with lung adenocarcinoma in non-smoking Asian women and highlight the importance of how the germline could inform risk for specific tumour mutation patterns, which could have important translational implications.

Association of variations in HLA class II and other loci with susceptibility to EGFR-mutated lung adenocarcinoma

Lung adenocarcinoma driven by somatic EGFR mutations is more prevalent in East Asians (30–50%) than in European/Americans (10–20%). Here we investigate genetic factors underlying the risk of this disease by conducting a genome-wide association study, followed by two validation studies, in 3,173 Japanese patients with EGFR mutation-positive lung adenocarcinoma and 15,158 controls. Four loci, 5p15.33 (TERT), 6p21.3 (BTNL2), 3q28 (TP63) and 17q24.2 (BPTF), previously shown to be strongly associated with overall lung adenocarcinoma risk in East Asians, were re-discovered as loci associated with a higher susceptibility to EGFR mutation-positive lung adenocarcinoma. In addition, two additional loci, HLA class II at 6p21.32 (rs2179920; P =5.1 × 10⁻¹⁷, per-allele OR=1.36) and 6p21.1 (FOXP4) (rs2495239; P=3.9 × 10⁻⁹, per-allele OR=1.19) were newly identified as loci associated with EGFR mutation-positive lung adenocarcinoma. This study indicates that multiple genetic factors underlie the risk of lung adenocarcinomas with EGFR mutations.

EGFR mutations in lung adenocarcinoma are more frequent in East Asians compared to other populations. Here, the authors carry out a genome-wide association study in EGFR mutant cancers and identify loci that are associated with risk of developing this molecular subtype of cancer.

Contribution of a Non-classical HLA Gene, HLA-DOA, to the Risk of Rheumatoid Arthritis

Despite the progress in human leukocyte antigen (HLA) causal variant mapping, independent localization of major histocompatibility complex (MHC) risk from classical HLA genes is challenging. Here, we conducted a large-scale MHC fine-mapping analysis of rheumatoid arthritis (RA) in a Japanese population (6,244 RA cases and 23,731 controls) population by using HLA imputation, followed by a multi-ethnic validation study including east Asian and European populations (n = 7,097 and 23,149, respectively). Our study identified an independent risk of a synonymous mutation at HLA-DOA, a non-classical HLA gene, on anti-citrullinated protein autoantibody (ACPA)-positive RA risk (p = 1.4 × 10(-9)), which demonstrated a cis-expression quantitative trait loci (cis-eQTL) effect on HLA-DOA expression. Trans-ethnic comparison revealed different linkage disequilibrium (LD) patterns in HLA-DOA and HLA-DRB1, explaining the observed HLA-DOA variant risk heterogeneity among ethnicities, which was most evident in the Japanese population. Although previous HLA fine-mapping studies have identified amino acid polymorphisms of the classical HLA genes as driving genetic susceptibility to disease, our study additionally identifies the dosage contribution of a non-classical HLA gene to disease etiology. Our study contributes to the understanding of HLA immunology in human diseases and suggests the value of incorporating additional ancestry in MHC fine-mapping.

Meta-analysis of genome-wide association studies identifies multiple lung cancer susceptibility loci in never-smoking Asian women

Genome-wide association studies (GWAS) of lung cancer in Asian never-smoking women have previously identified six susceptibility loci associated with lung cancer risk. To further discover new susceptibility loci, we imputed data from four GWAS of Asian non-smoking female lung cancer (6877 cases and 6277 controls) using the 1000 Genomes Project (Phase 1 Release 3) data as the reference and genotyped additional samples (5878 cases and 7046 controls) for possible replication. In our meta-analysis, three new loci achieved genome-wide significance, marked by single nucleotide polymorphism (SNP) rs7741164 at 6p21.1 (per-allele odds ratio (OR) = 1.17; P = 5.8 × 10(-13)), rs72658409 at 9p21.3 (per-allele OR = 0.77; P = 1.41 × 10(-10)) and rs11610143 at 12q13.13 (per-allele OR = 0.89; P = 4.96 × 10(-9)). These findings identified new genetic susceptibility alleles for lung cancer in never-smoking women in Asia and merit follow-up to understand their biological underpinnings.

Performance comparison of four commercial human whole-exome capture platforms

Whole exome sequencing (WXS) is widely used to identify causative genetic mutations of diseases. However, not only have several commercial human exome capture platforms been developed, but substantial updates have been released in the past few years. We report a performance comparison for the latest release of four commercial platforms, Roche/NimbleGen’s SeqCap EZ Human Exome Library v3.0, Illumina’s Nextera Rapid Capture Exome (v1.2), Agilent’s SureSelect XT Human All Exon v5 and Agilent’s SureSelect QXT, using the same DNA samples. Agilent XT showed the highest target enrichment efficiency and the best SNV and short indel detection sensitivity in coding regions with the least amount of sequencing. Agilent QXT had slightly inferior target enrichment than Agilent XT. Illumina, with additional sequencing, detected SNVs and short indels at the same quality as Agilent XT, and showed the best performance in coverage of medically interesting mutations. NimbleGen detected more SNVs and indels in untranslated regions than the others. We also found that the platforms, which enzymatically fragment the genomic DNA (gDNA), detected more homozygous SNVs than those using sonicated gDNA. We believe that our analysis will help investigators when selecting a suitable exome capture platform for their particular research.

Construction of a population-specific HLA imputation reference panel and its application to Graves' disease risk in Japanese

To fine map association signals of human leukocyte antigen (HLA) variants in the major histocompatibility complex (MHC) region, we constructed a Japanese population-specific reference panel (n = 908). We conducted trans-ancestry comparisons of linkage disequilibrium (LD) and haplotype structure for HLA variants using an entropy-based LD measurement, ɛ, and a visualization tool to capture high-dimensional variables. Our Japanese reference panel exhibited stronger LD between HLA genes than European or other East Asian populations, characterized by one population-specific common long-range HLA haplotype. We applied HLA imputation to genome-wide association study (GWAS) data for Graves' disease in Japanese (n = 9,003) and found that amino acid polymorphisms of multiple class I and class II HLA genes independently contribute to disease risk (HLA-DPB1, HLA-A, HLA-B and HLA-DRB1; P < 2.3 × 10(-6)), with the strongest impact at HLA-DPB1 (P = 1.6 × 10(-42)). Our study illustrates the value of population-specific HLA reference panels.

A Genome-wide Association Study of Periodontitis in a Japanese Population

Periodontitis is a multifactorial disease in which bacterial, lifestyle, and genetic factors are involved. Although previous genetic association studies identified several susceptibility genes for periodontitis in European populations, there is little information for Asian populations. Here, we conducted a genome-wide association study and a replication study consisting of 2,760 Japanese periodontitis patients and 15,158 Japanese controls. Although single-nucleotide polymorphisms that surpassed a stringent genome-wide significance threshold ( P < 5 × 10−8) were not identified, we found 2 suggestive loci for periodontitis: KCNQ5 on chromosome 6q13 (rs9446777, P = 4.83 × 10−6, odds ratio = 0.82) and GPR141-NME8 at chromosome 7p14.1 (rs2392510, P = 4.17 × 10−6, odds ratio = 0.87). A stratified analysis indicated that the GPR141-NME8 locus had a strong genetic effect on the susceptibility to generalized periodontitis in Japanese individuals with a history of smoking. In conclusion, this study identified 2 suggestive loci for periodontitis in a Japanese population. This study should contribute to a further understanding of genetic factors for enhanced susceptibility to periodontitis.

Abstract 62: A genome-wide association study identifies two new susceptibility loci for lung adenocarcinoma in the Japanese population

Adenocarcinoma is the most common type, comprising ˜40% of all lung cancer cases, and its incidence is increasing both in Asian and Western countries. The development of lung adenocarcinoma is more weakly associated with smoking than other histological types of lung cancer, such as squamous and small cell carcinomas, indicating that the mechanisms of carcinogenesis differ among these types. A better understanding of the genetic factors underlying lung adenocarcinoma development is strongly needed to elucidate the disease etiology and to identify high-risk individuals for targeted screening and/or prevention. To identify genetic factors that influence the risk of lung adenocarcinoma, we conducted a genome-wide association study and two validation studies in the Japanese population that consisted of a total of 6,029 lung adenocarcinoma cases and 13,535 controls (Shiraishi et al, Nat Genet, 2012).

Associations of two previously reported loci, 5p15.33 (rs2853677 in TERT; PCombined = 2.8x10-40, odds ratio (OR) = 1.41) and 3q28 (rs10937405 in TP63; PCombined = 6.9x10-17, OR = 1.25) (Landi et al, AJHG, 2009; Miki et al, Nat Genet, 2010), were validated. In addition, we identified two new susceptibility loci, 17q24.3 (rs7216064 in BPTF; PCombined = 7.4x10-11, OR = 1.20) and 6p21.3 (rs3817963 in BTNL2; PCombined = 2.7x10-10, OR = 1.18). BPTF encodes a chromatin remodeling factor that regulates transcription via specific recognition of methylated histone proteins. BPTF mRNA levels in noncancerous lung tissues were different depending on the genotype of the rs7216064 SNP (P = 0.02), implying a low expression from the risk allele. The BTNL2 gene encodes a T cell co-stimulatory molecule, and associations between BTNL2 SNPs and risk have been reported in several immune-related diseases. These data provide further evidence supporting genetic susceptibility to the development of lung adenocarcinoma.

Citation Format: Kouya Shiraishi, Hideo Kunitoh, Yataro Daigo, Atsushi Takahashi, Koichi Goto, Hiromi Sakamoto, Sumiko Ohnami, Yoko Shimada, Kyota Ashikawa, Akira Saito, Shunichi Watanabe, Koji Tsuta, Naoyuki Kamatani, Teruhiko Yoshida, Yusuke Nakamura, Jun Yokota, Michiaki Kubo, Takashi Kohno. A genome-wide association study identifies two new susceptibility loci for lung adenocarcinoma in the Japanese population. [abstract]. In: Proceedings of the AACR Special Conference on Post-GWAS Horizons in Molecular Epidemiology: Digging Deeper into the Environment; 2012 Nov 11-14; Hollywood, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2012;21(11 Suppl):Abstract nr 62.

HLA-Cw*1202-B*5201-DRB1*1502 haplotype increases risk for ulcerative colitis but reduces risk for Crohn's disease

BACKGROUND & AIMS

There are many genetic factors that are associated with both ulcerative colitis (UC) and Crohn's disease (CD). However, genetic factors that have distinct effects on UC and CD have not been examined.

METHODS

We performed a comparative genome-wide association study (GWAS) and a replication study using data from 748 patients with UC and 979 with CD, selected from a Japanese population. We conducted high-resolution (4-digit) genotyping of human leukocyte antigen (HLA) alleles in patients with UC and CD and additional 905 healthy individuals (controls). We performed haplotype-based analysis using data from the GWAS and HLA alleles to associate them with UC or CD.

RESULTS

The comparative GWAS and the replication study identified significant associations in the major histocompatibility complex region at 6p21 with UC and CD (rs9271366, P = 1.6 × 10⁻⁷⁰; odds ratio [OR] = 4.44). Haplotype-based analysis in the major histocompatibility complex region showed that HLA-Cw*1202-B*5201-DRB1*1502 haplotype was significantly associated with increased risk of UC compared with CD (P = 1.1 × 10⁻³³; OR = 6.58), accounting for most of the associations observed in the GWAS. Compared with the controls, this HLA haplotype significantly increases susceptibility to UC (P = 4.0 × 10⁻²¹; OR = 2.65), but reduces risk for CD (P = 1.1 × 10⁻⁷; OR = 0.40). Distinct effects of this HLA haplotype on UC and CD were independent of other HLA alleles and haplotypes (P = 2.0 × 10⁻¹⁹ and P = 7.2 × 10⁻⁵, respectively).

CONCLUSIONS

The HLA-Cw*1202-B*5201-DRB1*1502 haplotype increases susceptibility to UC but reduces risk for CD, based on a GWAS of a Japanese population.

Association of a novel long non-coding RNA in 8q24 with prostate cancer susceptibility

Recent genome-wide association studies reported strong and reproducible associations of multiple genetic variants in a large "gene-desert" region of chromosome 8q24 with susceptibility to prostate cancer (PC). However, the causative or functional variants of these 8q24 loci and their biological mechanisms associated with PC susceptibility remain unclear and should be investigated. Here, focusing on its most centromeric region (so-called Region 2: Chr8: 128.14-128.28 Mb) among the multiple PC loci on 8q24, we performed fine mapping and re-sequencing of this critical region and identified SNPs (single nucleotide polymorphisms) between rs1456315 and rs7463708 (chr8: 128,173,119-128,173,237 bp) to be most significantly associated with PC susceptibility (P = 2.00 × 10(-24) , OR = 1.74, 95% confidence interval = 1.56-1.93). Importantly, we show that this region was transcribed as a ∼13 kb intron-less long non-coding RNA (ncRNA), termed PRNCR1 (prostate cancer non-coding RNA 1), and PRNCR1 expression was upregulated in some of the PC cells as well as precursor lesion prostatic intraepithelial neoplasia. Knockdown of PRNCR1 by siRNA attenuated the viability of PC cells and the transactivation activity of androgen receptor, which indicates that PRNCR1 could be involved in prostate carcinogenesis possibly through androgen receptor activity. These findings could provide a new insight in understanding the pathogenesis of genetic factors for PC susceptibility and prostate carcinogenesis.

A functional variant in NKX3.1 associated with prostate cancer susceptibility down-regulates NKX3.1 expression

Genome-wide association studies (GWAS) identified multiple susceptible loci for prostate cancer (PC), and recent GWAS implicated that a common variant rs1512268 on chromosome 8p21 is associated with PC susceptibility, which is located at 14 kb downstream of a prostate tumor suppressor gene NKX3.1. To clarify a susceptibility gene and functional variants in this locus, we performed re-sequencing and fine mapping of this region and identified 12 candidates of functional single nucleotide polymorphisms that were absolutely linked with each other. Screening of these variants by RNA stability assay, electrophoretic mobility shift assay (EMSA) and reporter assay indicated that rs11781886 in the 5'-UTR of NKX3.1 displayed different binding affinity to nuclear proteins between the alleles, and that the transcriptional activity of the NKX3.1 promoter was significantly lower in the susceptible allele of this variant. Sp1 was determined to be the transcription factor that binds to the susceptible G allele, but not to the non-susceptible A allele. Allele-specific transcript quantification (ASTQ) and quantitative PCR analyses showed that the expression of NKX3.1 in the prostate was significantly lower in the subjects with the haplotype carrying the susceptible allele. These results suggest that the functional variant rs11781886 in the 5'-UTR of NKX3.1 can affect its transcription by altering the binding affinity of a transcriptional factor Sp1, and might result in PC susceptibility by lowering expression of NKX3.1 in the prostate.

Lack of association between variations of PDE4D and ischemic stroke in the Japanese population

BACKGROUND AND PURPOSE

After the first genomewide association study of ischemic stroke identified PDE4D as a susceptible gene, many replication studies have been conducted. However, the validity of the association has remained controversial because of the heterogeneity of both genetic markers and phenotypes.

METHODS

We investigated the association between variations of PDE4D and ischemic stroke by 3 methods: single-marker, haplotype, and tag-single nucleotide polymorphism (SNP) analyses. In the single-marker analysis, we evaluated the association using 2 large case-control samples (1112 cases and 1112 control subjects in a sample obtained from Kyushu, Japan, and 1711 cases and 1786 control subjects in BioBank Japan) and a prospective cohort with 14 years of follow-up. These samples were analyzed both separately and pooled. Haplotype and tag-SNP analyses were performed using the 2 case-control samples together.

RESULTS

In single-marker association tests, we found no significant association in the same direction among the 6 SNP reported in the initial study and ischemic stroke subtypes. Haplotype analysis revealed no significant association between the region around the 5'-end of the gene and combined atherothrombotic and cardioembolic infarction. Rs7730070, a SNP located around the 3'-end of PDE4D, showed the lowest nominal probability value by tag-SNP analysis but was not significant after adjustment for multiple testing (adjusted probability value =0.36).

CONCLUSIONS

These results suggest that variations in PDE4D are not associated with ischemic stroke risk in the Japanese population.

Lipoprotein(a) is a potential coronary risk factor

Lipoprotein(a) (Lp(a)) is recognized as a new coronary risk factor, but few studies have quantitatively assessed the relationship of serum Lp(a) levels with other coronary risk factors in many patients undergoing coronary cineangiography. Seventeen coronary risk factors were quantified (i.e., age, gender, hypertension, impaired glucose tolerance, cerebrovascular accident, hyperuricemia, smoking, family history of ischemic heart disease (IHD), history of hyperlipidemia, Lp(a), total cholesterol, high density lipoprotein (HDL)-cholesterol, triglyceride, low density lipoprotein-cholesterol, apolipoproteins(apo)A-I,B, E) to determine their relationship with the numbers of involved coronary vessels using multiple regression test in 1,006 patients who underwent coronary cineangiogram (280 non-IHD patients: 144 men, 136 women; 726 IHD patients: 460 men, 266 women; age 16-84 years, mean 60.5+/-0.3). Multiple regression test indicated R = 0.506 and items that showed high beta weight and significant p level were age, Lp(a), impaired glucose tolerance, total cholesterol, cerebrovascular accidents, HDL-cholesterol, smoking, gender, family history of IHD, and apo-A-I (0.221, p<0.001; 0.174, p<0.001; 0.616, p<0.001; 0.138, p<0.001; 0.122, p<0.001; -0.12, p<0.001; 0.092, p<0.01; 0.091, p<0.01; 0.067, p<0.05; -0.065, p<0.05; respectively). It was concluded that Lp(a) is an independent, potential, and modifiable coronary risk factor, and that reduction of serum Lp(a) is important in the clinical management of patients with IHD.

Evaluation of tissue plasminogen activator and plasminogen activator inhibitor-I levels in acute myocardial infarction

Fluctuations in tissue plasminogen activator (t-PA) activity, t-PA antigen, and plasminogen activator inhibitor-I (PAI-1) antigen levels were evaluated in blood samples obtained from 84 patients with initial uneventful acute myocardial infarction (AMI) and 35 patients with reinfarction and fatal infarction (patients with bad prognoses). Patients with initial AMI had significantly higher levels of t-PA activity than those of 14 patients with angina pectoris. Tissue plasminogen activator activity peaked between day 7 and 19 after the initial attack of AMI. Plasminogen activator inhibitor-I antigen level decreased significantly between day 2 and 19, then returned to the baseline levels of patients with angina pectoris nearly 4 weeks later. The t-PA activity levels of patients with reinfarction were significantly lower than those in patients without events between day 0 and 3 and between day 7 and 19. The percentage stenosis in the coronary arteries measured by coronary angiography was negatively correlated with t-PA activity. This information may help in selecting aggressive treatments such as thrombolysis by recombinant t-PA and predicting the prognosis for patients with AMI.

Microvascular sites and mechanisms responsible for reactive hyperemia in the coronary circulation of the beating canine heart

Our aim was to elucidate the site and mechanism responsible for reactive hyperemia in coronary circulation. In in vivo beating canine hearts, microvessels of the left anterior descending coronary artery (LAD) were observed through a microscope equipped with a floating objective. Flow velocity of the LAD was measured with a suction-type Doppler probe. The LAD was occluded for 20 or 30 seconds and then released, and reactive hyperemia was observed before and after 8-phenyltheophylline (7.5 mg/kg i.v.) or glibenclamide (200 micrograms/kg into the LAD) infusion. During the occlusion, only arterial microvessels smaller than 100 microns in diameter dilated. Dilation of those vessels was partially attenuated by 8-phenyltheophylline and completely abolished with glibenclamide. In the early phase of reactive hyperemia, all arterial microvessels dilated, and the magnitude of peak dilation was greater in vessels smaller than 100 microns compared with those larger than 100 microns. Vasodilation during reactive hyperemia ceased within 60 seconds in vessels smaller than 100 microns but was sustained for more than 120 seconds in those larger than 100 microns. 8-Phenyltheophylline did not change peak dilation of arterial microvessels but reduced dilation after the peak. Glibenclamide remarkably attenuated dilation of all arterial microvessels in the whole phase of reactive hyperemia. These results indicate that all arterial microvessels are responsible for reactive hyperemia after coronary artery occlusions of 20-30 seconds, but there is greater participation of vessels smaller than 100 microns in the early phase of reactive hyperemia. Dilation of vessels larger than 100 microns assumes an important role in the later phase. ATP-sensitive K+ channels mediate dilation of arterial microvessels both in brief ischemia and reactive hyperemia.

Effects of and adrenergic blockade on coronary arterial microvessels in the beating canine heart

OBJECTIVE

The aim was to clarify the effects of alpha and beta adrenergic blockade on coronary arterial microvessels and to assess the role of alpha and beta adrenergic tone in normally beating hearts.

METHODS

47 anaesthetised open chest dogs were studied. The diameters of epicardial arterial microvessels were measured in beating hearts using an incident light fluorescence microscope equipped with a floating objective. Drugs were infused into the left anterior descending coronary artery keeping the heart rate and aortic pressure at control levels. To examine the effect of alpha adrenergic blockade, phentolamine (100 micrograms.kg-1) was given in the absence or presence of beta adrenergic blockade (propranolol 50 micrograms.kg-1). To examine the effect of beta adrenergic blockade, propranolol (50 micrograms.kg-1) or three doses of ICI 118,551 (a selective beta 2 antagonist, 0.1, 0.5, and 1.0 microgram.kg-1.min-1) was given.

RESULTS

Coronary arterial microvessels were divided into three groups according to the control diameters (D) of small (D less than 100 microns), medium (100 less than or equal to D less than 200 microns) and large (D greater than or equal to 200 microns) groups. In the absence of beta adrenergic blockade, phentolamine significantly dilated all vessel groups: small +19.6 (SEM 5.6)%, medium +5.8(2.3)%, large +5.3(0.9)%. In the presence of beta adrenergic blockade, the vasodilator effect of phentolamine was completely abolished. Propranolol constricted all vessel groups: small -3.6(1.1)%, medium -4.8(1.0)%, large -3.5(1.0)%. ICI 118,551 significantly constricted the large vessel group [-2.5(0.6)%] at the mid dose, and the medium and large vessel groups [medium -3.1(0.8)%, large -3.5(1.3)%] at the highest dose.

CONCLUSIONS

These data indicate that (1) the vasodilator effect of phentolamine is induced by beta adrenergic stimulation; (2) resting alpha adrenergic tone of coronary arterial microvessels is minimal in normally beating hearts, and (3) resting beta adrenergic tone may play a physiological role in coronary arterial microvessels, and beta 2 adrenergic tone predominates in arterial microvessels greater than 100 microns in diameter.

Neuropeptide Y modulates vasoconstriction in coronary microvessels in the beating canine heart

The purpose of this study was to determine whether neuropeptide Y has a direct vasoconstrictor effect at low doses, mimicking the physiological plasma concentration on the specific site(s) of coronary arterial microvessels in in situ beating canine left ventricles. Coronary microvessels were directly observed by means of an intravital microscope and video system equipped with a floating objective. Epi-illuminated fluorescence coronary microangiography was performed in open-chest anesthetized dogs (n = 14) to examine the changes in internal diameter of epimyocardial arterial microvessels. Flow velocity of fluorescently labeled microshperes in capillaries was also measured (n = 6). To eliminate secondary effects of neuropeptide Y on coronary microvessels via autonomic nervous modulation, experiments were conducted under pharmacological blockade of the regional autonomic nervous system by intracoronary injection of propranolol, 50 micrograms/kg; phentolamine, 100 micrograms/kg; and atropine, 5 micrograms/kg. Aortic pressure and heart rate were kept constant during the experiments. Intracoronary infusion of three different doses of neuropeptide Y (1, 10, and 100 pmol/kg/min) for 5 minutes significantly constricted small microvessels (less than 100 microns in diameter) (-5.2 +/- 1.4%, -8.5 +/- 1.5%, and -14.0 +/- 1.7%; p less than 0.05 versus before neuropeptide Y at each dose), medium microvessels (100-200 microns in diameter) (-5.5 +/- 1.6%, -10.6 +/- 1.8%, and -16.8 +/- 2.1%, p less than 0.05 versus before neuropeptide Y at each dose), and large microvessels (greater than 200 microns in diameter) (-3.6 +/- 0.6%, -5.8 +/- 0.8%, and -10.0 +/- 1.1%; p less than 0.05 versus before neuropeptide Y at each dose) in a dose-dependent manner. Capillary flow velocity was reduced by 17.2 +/- 3.1% by an intracoronary dose of 100 pmol/kg/min of neuropeptide Y (p less than 0.05). The present study indicates that low doses of neuropeptide Y exert a homogeneous direct vasoconstrictor effect on various sizes of coronary arterial microvessels and reduce capillary flow velocity. These results suggest that neuropeptide Y may play a physiological role in modulating coronary microvascular tone.

[t-PA activity, antigen and PAI-1 antigen levels in blood obtained from the patients with cerebral infarction]

Tissue plasminogen activator (t-PA) produced by endothelial cells exerts a powerful effect on the course of thrombosis, embolism, or arteriosclerosis. However, the fluctuations of fibrinolytic system in the patients with cerebral infarction (CI), have yet to be demonstrated. This study was designed to investigate t-PA activity, t-PA antigen and plasminogen activator inhibitor-1 (PAI-1) antigen levels in the CI patients. The mean t-PA activity, t-PA antigen and PAI-1 levels in patients were 0.53 +/- 0.64 IU/ml, 10.9 +/- 5.2 ng/ml and 23.0 +/- 14.9 ng/ml, and the normal ranges were 0.02-0.28 IU/ml, 1.0-7.0 ng/ml and 5.3-45.0 ng/ml, respectively. Almost all the patients were plotted out to the abnormal range by scattergrams relating t-PA activity to t-PA antigen, and no daytime fluctuations of the above three parameters in the patients differed from those in normal controls. When CI patients were followed up to the 8th hospital day, abnormal fluctuations were also observed. Consequently we suggest that this information may help to attain the more progressive treatment or the preventive therapy of CI.

Diameter change and pressure-red blood cell velocity relations in coronary microvessels during long diastoles in the canine left ventricle

The objective of this study was to determine whether coronary vascular resistance remains constant during long diastoles and whether critical closure of arterial microvessels occurs at zero-flow pressure. For this purpose, we directly measured internal diameters and red blood cell velocities in arterial and venous coronary microvessels during long diastoles under maximal vasodilation. The epicardial coronary microcirculation was viewed in anesthetized, open-chest mongrel dogs through an intravital microscope equipped with a newly developed floating objective. Coronary microvascular diameters and red blood cell velocities were measured with high-speed cinematography. During maximal vasodilation (150 micrograms/kg body wt i.v. dilazep), long diastoles were induced by vagal nerve stimulation. Internal diameters of all small arteries and arterioles (n = 12) gradually declined with decreasing aortic pressure during long diastoles, and the reduction of the diameter was greatest when aortic pressure was less than 35 mm Hg. The mean internal diameter (88.8 +/- 52.2 microns) at minimal aortic pressure (19.2 +/- 6.4 mm Hg) was significantly less than that at an aortic pressure of 100 mm Hg (116.2 +/- 68.5 microns, p less than 0.01). The internal diameters of small veins and venules remained nearly constant during long diastoles. When red blood cell progression in coronary microvessels stopped at the nadir of aortic pressure, all arterial coronary microvessels remained open; that is, there was no evidence of "critical closure."(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of afterload elevation on the ischemic myocardium in isolated, paced canine heart with partial coronary stenosis

The effect of afterload elevation on the ischemic myocardium was examined in an isolated, paced canine heart with a partial coronary stenosis. The coronary blood flow of the left circumflex coronary artery was reduced to approximately one-third of the values before stenosis. The left circumflex coronary stenosis produced a decrease in global ventricular function, a decrease in systolic shortening and deviation of the ST-segment of the epicardial electrocardiogram and an increase in myocardial carbon dioxide (CO2) tension of the ischemic region. Then, afterload elevation with constant preload decreased the myocardial CO2 tension and improved the ST-segment deviation of the ischemic myocardium. Mechanical function, estimated by the relation between mean aortic pressure and systolic shortening, also improved with elevation of mean aortic pressure. In contrast, afterload elevation combined with preload elevation did not improve ischemic injury, as estimated by myocardial CO2 tension, and did not improve ST-segment deviation or mechanical function despite an increase in left circumflex coronary flow. These results suggest that the elevation of afterload pressure under constant preload improves ischemia produced by a partial coronary stenosis due to increased coronary blood supply; however, the preload elevation counterbalances the beneficial effects of afterload elevation.

Load dependency of end-systolic pressure-volume relations in isolated, ejecting canine hearts

If characteristic muscle properties such as myocardial viscosity and/or shortening deactivation influence left ventricular ejection in the whole heart, the slope of the left ventricular end-systolic pressure-volume relation should be a function of both the contractile state and the loading mode. Thus, the load dependence of the end-systolic pressure-volume relation was examined using isolated, perfused canine hearts ejecting saline into a hydraulic loading system. The instantaneous left ventricular volume was measured with a plethysmograph. Under constant coronary flow and heart rate, two regression lines for end-systolic pressure-volume relations in two sets of loading modes were obtained: (1) Preload (left ventricular end-diastolic pressure; 4-15 mmHg) changes under fixed afterload impedance (preload changes); (2) Afterload impedance (peripheral resistance; 1.9-9.6 x 10(3) dyn sec cm-5) changes under fixed left ventricular end-diastolic volume (afterload changes). The slope of the end-systolic pressure-volume relation with afterload changes was steeper than that with preload changes (6.3 +/- 0.7 vs 4.8 +/- 0.6 mmHg/ml, p less than 0.05). Accordingly, under constant coronary flow, the slope of the end-systolic pressure-volume relation depended on loading conditions within the physiological range of afterload impedance and preload. This finding supports our hypothesis and implies that the slope change is of limited value as a contractile index in the ejecting heart.

Effects of changes in afterload impedance on left ventricular ejection in isolated canine hearts: dissociation of end ejection from end systole

To examine how end systole differs from end ejection and also whether the slope of the end systolic pressure-volume relation can be approximated to that of the end ejection pressure-volume relation, nine isolated, perfused, paced canine hearts ejecting into a hydraulic loading system that simulated the aortic input impedance of a dog's arterial tree were studied. To measure left ventricular volume changes the heart was placed in a plethysmograph. Peripheral resistance (Rp) and arterial compliance (C) were independently varied from 1.9 (Rp = 1.9) to 3.3, 6.4, and 9.6 X 10(8) Pa.m-3.s (Rp run) with a constant value of compliance 1.3 X 10(-9) Pa-1.m3 (C = 1.3), and from C = 0.4 to C = 0.8, C = 1.3 and C = 2.3 (C run) with a constant value of resistance (Rp = 6.4). Five pressure-volume loops were obtained by changing the end diastolic volume at each value of compliance and peripheral resistance. It was clearly shown that ventricular ejection continued after end systole and the time duration between end systole and end ejection became longer with increasing arterial compliance (24(4) at C = 0.4 vs 49(4) ms at C = 2.3, p less than 0.001), while the time duration between end diastole and end systole was constant regardless of afterload impedance change. Regarding the left ventricular pressure-volume relation the end systolic relation was almost linear (r greater than or equal to 0.98) and the slope was not significantly affected by change in any afterload impedance tested. End ejection pressure-volume relation was also linear (r greater than or equal to 0.97) and the slopes in the peripheral resistance and compliance runs were lower than those of the end systolic pressure-volume relation in each corresponding run. The former slopes decreased at smaller values of Rp or larger values of C--namely, 4.4(0.6) at Rp = 9.6 vs 3.6(0.6) at Rp = 1.9, p less than 0.05; 4.8(0.6) at C = 0.4 vs 3.1(0.5) mmHg.ml-1 at C = 2.3, p less than 0.001. Thus it is concluded that end ejection is usually different from end systole and the time difference between them is affected by changes in arterial compliance. In addition, the slope of end ejection pressure-volume relation was dependent on the changes in afterload impedance and cannot be approximated to that of the end systolic pressure-volume relation.

Phasic blood flow velocity pattern in epimyocardial microvessels in the beating canine left ventricle

We quantitated phasic epimyocardial microcirculatory coronary blood flow velocity patterns in the beating left ventricle. Using a newly developed floating objective and high-speed cinematography, red cell velocities in small arterioles, capillaries, and small venules and microvascular diameters in the superficial layer of the epimyocardium of beating left ventricle were determined throughout the entire cardiac cycle in open-chest anesthetized dogs. Heart rate was maintained at 140 beats/min by means of left atrial pacing. Peak red cell velocity was observed in midsystole in small arterioles and capillaries, and in late systole in small venules. Abrupt decline in red cell velocity and, in many cases, a momentary cessation or reverse of flow, was observed in these microvessels during the pre-ejection period. The internal diameter of small venule was increased in late systole, while that of small arteriole remained almost constant during the cardiac cycle. Furthermore, in these epimyocardial microvessels, a higher percentage of the total area under the velocity curve occurred during the ejection phase; 51% in small arterioles, 43% in capillaries, and 40% in small venules. These findings indicate that the phasic blood flow pattern is markedly different in the subepimyocardial microvessels from that in the large epicardial artery and the septal artery. During vasodilation following dilazep (50 micrograms/kg, i.v.), an adenosine potentiator, red cell velocity increased throughout the entire cardiac cycle in epimyocardial microvessels with significant increases in the total area under the velocity curves accompanied by significant dilation of the arterioles. The present data will provide information useful in predicting or simulating transmural differences in the phasic blood flow pattern.

Effects of preload alteration on the degree of ischemia and function of ischemic myocardium under constant mean aortic pressure, coronary perfusion pressure and heart rate in isolated perfused canine heart

We examined the effects of preload alteration on global and regional (i.e., non-ischemic and ischemic areas) function in the presence of regional myocardial ischemia and on the degree of ischemia using 18 isolated, metabolically supported canine left ventricles. For this purpose, cardiac output (CO), systolic segment length change (SL), myocardial CO2 tension (PmCO2) and ST level of epicardial ECG were measured at 3 levels of left ventricular end-diastolic pressure (LVEDP), i.e., approximately 7 (low LVEDP), 11 (middle LVEDP), and 16 mmHg (high LVEDP) without and with left circumflex artery (LCx) stenosis under a constant mean aortic pressure (90 mmHg), mean coronary perfusion pressure (90 mmHg) and heart rate. In the Pre-ischemic stage, CO and SL increased significantly when LVEDP was elevated in a stepwise fashion by changing the height of the reservoir connected to the left atrium. There were no significant changes in PmCO2 or ST level. On the other hand, with LCx stenosis, CO did not show a subsequent increase at higher LVEDPs (i.e., from 796 +/- 103 ml/min at middle LVEDP to 931 +/- 153 ml/min at high LVEDP). Furthermore, there was no significant SL response in the LCx area following alterations of LVEDP, although there was considerable lengthening of end-diastolic length. Both increased PmCO2 and ST level of the LCx area, following LCx stenosis, further increased significantly with elevation of LVEDP. These results suggest the possibility that considerable elevation of LVEDP worsens the degree of ischemia and does not significantly augment ischemic regional myocardial function or global function, while mild elevation of preload improves or tends to improve simultaneously regional ischemic and global functions without aggravating the ischemic injury significantly. Therefore, we conclude that the preload level is quite important in managing ischemia induced myocardial dysfunction.

A comparison of ST segment deviation and calculated solid angle during acute regional ischemia in the isolated canine heart at precordial, epicardial and intramyocardial lead surfaces

Although solid angle analysis has been considered to be reasonable for explaining the distribution of ST segment deviation following ischemia, it has not been tested fully, especially for ST segment changes in various sites at different lead surfaces. Thus, we investigated the applicability of solid angle theory to the mechanism of ischemic ST segment deviation at intramyocardial, epicardial and precordial leads. We used seven isolated, coronary perfused, isovolumic contracting canine hearts in a homogeneous cylindrical volume conductor. ST segment potentials from 246 electrodes were continuously measured during left circumflex coronary artery occlusion for five minutes. The ischemic boundary was obtained from a postmortem angiography, and the solid angle subtended by the ischemic boundary was calculated at every electrode site. Despite the difference between epicardial and precordial ST segment potential distributions, there was a high correlation between measured ST segment potential and calculated solid angle at epicardial (r = 0.86 +/- 0.05, 0.77-0.93), precordial (r = 0.93 +/- 0.05, 0.84-0.99), and intramyocardial leads (r = 0.95 +/- 0.03, 0.91-0.99). We conclude that solid angle analysis can be used to approximate the distribution of ischemic ST segment deviation at different lead surfaces in acute ischemia.

Effects of major coronary artery stenosis on the pressure-flow relationship of an adjacent intact coronary artery branch in isolated supported canine left ventricle

We investigated whether the relationship between the mean left anterior descending and septal coronary blood flow and the mean perfusion pressure varies with left circumflex coronary stenosis. We used excised, perfused canine heart preparations (n = 10), in which variables to influence the myocardial oxygen demand and supply relation can be fairly well controlled. The results showed that coronary blood flow in the adjacent, non-stenosed coronary artery increased significantly following LCX stenosis; this increased flow was found at the same values of heart rate, left ventricular end-diastolic pressure and perfusion pressure, as those in the preischemic state. Moreover, this increased flow was also observed when the values of peak left ventricular pressure and pressure-length loop area were similar between the pre-ischemic and ischemic states. Thus, contributions of neurohumoral factors or alterations in mechanical factors determining the myocardial oxygen demand and supply relation are negligible. This increased flow may be important in maintaining overall cardiac function in cases of acute coronary stenosis or coronary occlusion.

The changes in ECG ST segment and mechanical function of regional ischemic myocardium during afterload reduction in isolated dog hearts with coronary stenosis

By measuring ECG ST segment deviation and regional mechanical dysfunction, we assessed the effects of an alteration in afterload pressure on regional myocardial ischemia due to a partial coronary occlusion of the left circumflex coronary artery (CFX). Eight isolated, perfused and paced dog hearts were loaded with an artificial arterial system which simulated the aortic input impedance of the dog arterial tree. Afterload pressure was altered by stepwise changes in peripheral resistance (Rp), while left ventricular end-diastolic pressure (LVEDP) and heart rate were kept constant. Coronary perfusion pressure (CPP) was kept equal to mean aortic pressure (AoP). ECG and myocardial systolic segment shortening (SS) were measured in both areas perfused by the CFX and the left anterior descending coronary artery (LAD). In the presence of CFX stenosis, mean AoP decreased from 96 +/- 7 to 46 +/- 7 mmHg following a decrease in Rp and cardiac output increased progressively from 465 +/- 30 to 1055 +/- 100 ml/min. In this situation, CFX coronary blood flow decreased from 75 +/- 2 to 28 +/- 6 ml/100 g/min. Epicardial ECG in the ischemic region showed two types of ST segment deviation after CFX stenosis: ST segment elevation and ST segment depression. Moreover, following afterload reduction, these individual ECG ST segment changes showed further deviations. The levels of mean AoP, below which further ST segment deviations significantly occurred, were as follows: 71 +/- 6 mmHg in ST segment elevation cases and 52 +/- 7 mmHg in ST segment depression cases. Myocardial systolic segment shortening in the ischemic region also significantly decreased following CFX stenosis (91 +/- 8% of pre-ischemic control, p less than 0.05). Then, during afterload reduction, SS in the CFX area appeared to be bimodal and it definitely decreased when mean AoP was 46 +/- 7 mmHg. To enhance the sensitivity of detection of further mechanical dysfunction throughout afterload reduction following regional myocardial ischemia, we calculated percentage values of the SS in the CFX area to the SS in the LAD area at each Rp. By this normalization, mechanical dysfunction was found when mean AoP was below 67 +/- 5 mmHg. These results suggest that reduction in afterload pressure below a certain level aggravated the regional ischemia, despite an increase in cardiac output, and to detect this change in the ischemic region during afterload reduction, ECG ST segment deviation seems to be a useful indicator.(ABSTRACT TRUNCATED AT 400 WORDS)

Effects of coronary artery stenosis on left ventricular end-ejection pressure-ejected volume relationships in isolated perfused canine hearts

We investigated the behavior of the left ventricular end-ejection pressure-ejected volume relation with and without left circumflex coronary stenosis in isolated perfused canine hearts. To change ventricular afterload pressure, the peripheral resistance of the hydraulic model attached to the aortic root of the excised hearts was changed in a stepwise fashion to five different levels. The end-ejection pressure-ejected volume relationship was nearly linear in both pre-ischemic and ischemic states. The slope changes following left circumflex coronary stenosis differed among the hearts used in the present study, and there was no significant difference in average slope (n = 10) between the pre-ischemic and ischemic states (i.e., -7.4 +/- 1.0 and -8.4 +/- 1.2 mmHg/ml, respectively). Therefore, the, slope of the relation was not useful in judging the presence of depressed ventricular function induced by coronary stenosis. In contrast, the ejected volume axis intercept decreased significantly from 16.5 +/- 1.1 ml to 13.6 +/- 1.1 ml (p less than 0.05) with regional ischemia.

ST segment changes under occlusion of the proximal portion of major coronary arteries in the isolated canine heart

We studied the mechanisms of ST segment displacement in the ECG recorded from the epi- and subendocardium of ischemic ventricles in the isolated and perfused canine heart. ST segment changes were observed in association with a relatively large area of ischemia produced by occlusion of the left anterior descending and septal arteries (LAD + Sept.) or of the left circumflex artery (LCx). Contrary to previous reports, we found that the amount of subendocardial ST elevation was not always greater than that in the epicardial ECG recorded at the center of ischemia. Also, in the non-ischemic area, the degree of the ST depression in the subendocardial record was nearly the same as the epicardial record. On the other hand, the degree of the epicardial ST elevation on the border zone was always smaller than that at the ischemic center, which seemed to be due to the broadness of the border zone. The amplitude of the ST depression in the non-ischemic area was greater when the recording electrode was near the ischemic border, which supports the solid angle theory. The degrees of both ischemic ST elevation and reciprocal ST depression in the LCx perfused area were always greater than in the LAD + Sept. perfused area. These results strongly suggest that ST segment displacement depends on the relative position of the recording electrode to the electric double layer which exists at the border between the ischemic and non-ischemic area.

A new microscopic system for the continuous observation of the coronary microcirculation in the beating canine left ventricle

A microscope system was designed using a new type of objective lens which makes possible the direct and continuous observation of the coronary microcirculation throughout the entire cardiac cycle in the beating canine heart. The microscope system consists of a standard microscope and a floating objective system which is composed of a pair of convex lenses and transmits a real image of the coronary microcirculatory bed to a standard microscope without any change in magnification. The convex lens facing the heart is supported by a weight-adjusting coil spring and low-resistance ball bearings which allow the lens to move perpendicularly in unison with cardiac motion. To reduce excessive cardiac movement, two 24-gauge needles connected to the animal table by a needle holder are horizontally inserted through the midmyocardium of the left ventricle beneath the area of interest. The epimyocardium of the left ventricle is transilluminated by means of a light pipe and a xenon-arc lamp. The distance between the floating lens and the cardiac surface is kept constant using a spacing device connected to the light pipe holder to prevent the compression of the tissue in the microscopic field of view. This improvement in the microscope system combined with high-speed cinematography greatly facilitates the continuous analysis of the coronary microcirculation in the beating left ventricle throughout the entire cardiac cycle, and may provide a useful approach to the understanding of the regulation mechanism of the coronary circulation.