Biomarkers associated with vulnerable plaques

Background

Cardiovascular heart disease is the leading cause of mortality worldwide, with the rupture or thrombosis of an atherosclerotic plaque being the main reason behind an acute coronary syndrome. It has already been established that the morphology of atherosclerotic plaques determine their stability. A lipid rich lesion with a thin fibrous cap is more prone to rupture compared to solid fibrous lesions. In the PROSPECTII study we used Near infrared spectroscopy (NIRS) and Intravascular ultrasound (IVUS) to identify atherosclerotic plaques in the coronary arteries; NIRS-derived lipid core burden index (LCBI) and IVUS-derived plaque burden (PB) identified plaques that caused adverse cardiovascular events.

Purpose

Our aim is to find biomarkers associated with LCBI or PB, to understand the development of vulnerable plaques.

Methods

902 patients were enrolled in this study after successful percutaneous coronary intervention (PCI). A combined NIRS-IVUS catheter was then used to analyze approximately 200m of coronary arteries. Blood samples for biomarker analysis were taken before the PCI procedure and plasma levels of 182 proteins associated with cardiovascular disease were assessed using a novel method for measuring proximity extension assay. Adjusted linear regression models were calculated between the biomarkers and the outcomes of interest, followed by a false discovery rate (FDR) correction.

Results

We found 24 proteins associated with plaque burden and 28 proteins associated with LCBI after using a cut off of two tailed P value <0.05. An overlap of 8 biomarkers could be seen between the two groups. After adjusting the P values with FDR, Angiopoeitin like 3 (ANGPTL3) retained its association to LCBI, and Interleukin 18 receptor 1 (IL18R1) and colony stimulating factor 1 (CSF-1) to plaque burden.

Conclusion

We were able to identify different biomarker patterns associated with plaque burden compared to lipid rich vulnerable plaques. ANGPTL3 was shown to only have an association with lipid rich plaques and not with solid fibrous lesions which further supports its role in vulnerable plaques.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Abbott Vascular, Infraredx, and The Medicines Company

Heterogeneous plaque geometry is associated with major adverse cardiovascular events

Objectives

To determine whether coronary artery plaque-lumen geometry predicts major adverse cardiovascular events (MACE), and incorporating geometric measures enhances risk stratification from intravascular imaging.

Background

Prospective studies show that only a minority of plaques with higher-risk features result in future MACE, indicating the need for more predictive markers of plaque vulnerability. Plaques show heterogeneous structures and plaque-lumen geometry, both of which can promote high plaque structural stress (PSS); however, the relationships between geometric heterogeneity and MACE or PSS are unknown.

Methods

We examined plaque-lumen curvature, irregularity, lumen aspect ratio (LAR), roughness, PSS and their longitudinal heterogeneity (Figure 1A) in 35 non-culprit lesions (NCL) associated with MACE and 66 propensity-matched no-MACE NCL from the PROSPECT (Providing Regional Observations to Study Predictors of Events in the Coronary Tree) study. Causes of heterogeneous geometry and PSS were examined using a separate group of co-registered virtual histology-intravascular ultrasound (VH-IVUS) and optical coherence tomography (OCT) images (n=53 plaques).

Results

Plaque geometry heterogeneity indices (HI) were increased in NCL MACE vs. no-MACE lesions across the whole plaque and peri-minimal luminal area (MLA) segments (HI curvature: p=0.002; HI irregularity: p<0.001; HI LAR: p=0.001; HI roughness: p=0.002). Peri-MLA HI roughness was an independent predictor of future MACE (hazard ratio: 3.69, p<0.001) (Figure 1B). Inclusion of HI roughness improved identification of NCLs leading to MACE in VH-defined thin-cap fibroatheromas (VH-TCFA, p=0.005), MLA ≤4mm2 (p=0.001), and plaque burden (PB) ≥70% (p<0.001) (Figure 1C–E), and further improved the ability of PSS to identify MACE NCLs in VH-TCFA (p=0.041), MLA ≤4mm2 (p=0.033), and PB ≥70% (p<0.001). HI roughness generally corresponded with HI PSS, but was also increased at sites of local calcification and multilayering.

Conclusions

Plaque-lumen geometric heterogeneity is increased across whole plaque and peri-MLA segments of NCLs causing MACE. Inclusion of geometric heterogeneity may improve the ability of intravascular imaging to predict MACE.

Funding Acknowledgement

Type of funding sources: Other. Main funding source(s): British Heart Foundation

P869Predictive value of the endothelial shear stress distribution in three-dimensional quantitative coronary angiography models in detecting vulnerable plaques

Background

Low Endothelial shear stress (ESS) is a well-known instigator of coronary atherosclerosis. Prospective intravascular ultrasound (IVUS)-based imaging studies with computational fluid dynamic analysis revealed its predictive merit in-vivo. However, whether coronary modelling derived from quantitative coronary angiography (QCA) is equally effective in detecting high-risk plaques remains to be established.

Purpose

To examine the value of endothelial shear stress (ESS) estimated in three-dimensional (3D) QCA models in detecting plaques that are likely to progress and cause events.

Method

We analysed the baseline intravascular ultrasound virtual histology (IVUS-VH) and angiographic data from 28 non-culprit lesions with a vulnerable phenotype (i.e., fibroatheroma or thin cap fibroatheroma) that caused major adverse cardiac events or required revascularization (nc-MACE-R) at 5-year follow-up and from a control group of 119 vulnerable plaques that remained quiescent. The segments studied by IVUS-VH at baseline were reconstructed using 3D-QCA software and in the obtained geometries blood flow simulation was performed and we estimated the resting Pd/Pa across the vulnerable plaque and the mean ESS values in 3mm sub-segments. A propensity score was built by the baseline plaque characteristics and the hemodynamic indices and its efficacy in detecting nc-MACE-R lesions was examined.

Results

Nc-MACE-R lesions were longer (32.5mm [18.0, 41.6], vs. 19.6mm [12.7, 31.3], p=0.03), had smaller minimum lumen area (MLA) (3.65mm2 [3.26, 4.36] vs. 5.03mm2 [3.98, 6.66], p<0.01), increased plaque burden (PB) (69.4% [63.5, 72.0] vs. 60.8% [53.7, 66.5], p<0.01), were exposed to higher ESS (9.40Pa [6.3, 12.5] vs. 4.1Pa [3.0, 6.9], p<0.01), and exhibited a lower resting Pd/Pa (0.97 [0.95, 0.98] vs. 0.98 [0.97, 0.99], p<0.01]. In multivariable analysis the only independent predictor of nc-MACE-R was the maximum 3mm ESS value (hazard ratio: 1.08 [1.02, 1.16], P=0.016). Lesions exposed to high ESS (>4.95Pa) with a high-risk anatomy (MLA<4mm2and PB>70%) had a higher nc-MACE-R rate (53.8%) than those with a low-risk anatomy exposed to high ESS (31.6%) or those exposed to low ESS that had high (20.0%) or low-risk anatomy (7.1%, P<0.001).

Conclusion

In the present study, 3D-QCA-derived local hemodynamic variables provided useful prognostic information and in combination with lesion anatomy enabled more accurate identification of nc-MACE-R lesions. Further research in a larger number of patients is need to confirm these findings before the conduction of large scale prospective studies that will combine intravascular imaging and 3D-QCA modelling to more accurately detect vulnerable plaques.

[Fungal endocarditis found at onset of lower limb acute aortic occlusion; report of a case]

Fungal endocarditis caused by Candida species is associated with high morbidity and mortality. A combination of surgical resection and antifungal drug therapy is the golden standard for treatment. We reported a case of fungal endocarditis due to Candida lusitaniae found at onset of lower limb acute aortic occlusion cured by emergency operation. This case suggests that Candida endocariditis can be managed medically with antifungal drug therapy in life time.

Comparative efficacy of gamma-irradiation for treatment of in-stent restenosis in saphenous vein graft versus native coronary artery in-stent restenosis: An intravascular ultrasound study

BACKGROUND

We used serial volumetric (post-irradiation and follow-up) intravascular ultrasound (IVUS) to compare the effectiveness of gamma-irradiation ((192)Ir) in saphenous vein graft (SVG) versus native coronary artery in-stent restenosis (ISR).

METHODS AND RESULTS

The study population consisted of 47 patients with native coronary artery ISR from WRIST (Washington Radiation for In-Stent Restenosis Trial) and 31 patients with SVG ISR (12 from the WRIST and 19 from SVGWRIST). After irradiation and at 6-month follow-up, stent, lumen, and intimal hyperplasia (IH, stent minus lumen) areas were measured every 1 mm. ISR length was similar in the 2 groups (29+/-12 versus 29+/-14 mm, P=0.9). Post-intervention measurements of stent (280+/-154 versus 324+/-270 mm(3), P=0.4), lumen (184+/-91 versus 214+/-172 mm(3), P=0.3), and IH (96+/-77 versus 109+/-119 mm(3), P=0.5) volumes were similar in the 2 groups. The post-intervention minimum lumen cross sectional areas tended to be smaller in native artery ISR lesions (4.7+/-1.7 versus 5.4+/-1.6 mm(2), P=0.11). During follow-up, there was a slight increase in IH volume (9+/-38 mm(3)) in native artery ISR lesions and a slight decrease in IH volume in SVG ISR lesions (-9+/-32 mm(3), P=0.0463). There was also a slight decrease in minimum lumen area in the native artery ISR lesions versus a slight increase in minimum lumen area in the SVG ISR lesions (-0.8+/-1.7 versus 0.2+/-1.1, P=0.0087). As a result, the follow-up minimum lumen area in native artery lesions was smaller than in SVG ISR lesions (4.1+/-2.1 mm(2) versus 5.6+/-2.2 mm(2), P=0.0067).

CONCLUSION

gamma-Irradiation with (192)Ir brachytherapy appears to be as effective in SVGs as it is in native artery ISR lesions.

Evidence for high incidence of end-stage renal disease in patients after stroke and acute myocardial infarction at age 60 or younger

The impact of stroke and acute myocardial infarction (AMI) on the incidence of end-stage renal disease (ESRD) is unknown. Two community-based registries, one of patients with stroke or AMI and another of patients with ESRD who undergo dialysis, are available in Okinawa, Japan. Whether survivors after stroke and AMI who were registered from April 1988 through March 1991 entered an ESRD dialysis program by the end of December 1999 was determined. Among 4,556 patients (3,809 patients with stroke, 747 patients with AMI) who survived at least 28 days after the event onset, 44 patients (36 patients, stroke; 8 patients, AMI) entered an ESRD dialysis program during the study period. The 10-year cumulative incidence of ESRD was approximately 2.0% in those who survived stroke or AMI. The observed-expected ratio was 4.1 in men (P < 0.01) and 5.8 in women (P < 0.01) aged 30 to 59 years and 0.8 in men (not significant) and 0.4 in women (not significant) 60 years and older. The present results confirm that survivors after stroke or AMI have a greater incidence of ESRD than those in the general population, in particular, those who had stroke or AMI at 60 years or younger.

An intravascular ultrasound classification of angiographic coronary artery aneurysms

The purpose of this study was to use intravascular ultrasound (IVUS) to clarify the morphology of coronary aneurysms diagnosed by angiography. Seventy-seven consecutive patients with an aneurysmal dilatation in a native coronary artery diagnosed by angiography (defined as a lesion lumen diameter 25% larger than reference) were evaluated by IVUS. IVUS true aneurysms were defined as having an intact vessel wall and a maximum lumen area 50% larger than proximal reference. IVUS pseudoaneurysms had a loss of vessel wall integrity and damage to adventitia or perivascular tissue. Complex plaques were lesions with ruptured plaque or spontaneous or unhealed dissection. Aneurysmal dilatation and reference segments were assessed using standard IVUS quantitative techniques. Twenty-one lesions (27%) were classified as true aneurysms, 3 (4%) were classified as pseudoaneurysms, 12 (16%) were complex plaques, and the other 41 (53%) were normal arterial segments adjacent to > or =1 stenosis. The maximum lumen area within the aneurysmal segment was largest for pseudoaneurysm (35.1 +/- 10.4 mm(2)), 22.1 +/- 9.9 mm(2) for true aneurysm, and similar for complex plaques (11.2 +/- 3.5 mm(2)) and normal segments with adjacent stenoses (13.8 +/- 6.4 mm(2)): analysis of variance, p <0.0001. Only one third of angiographically diagnosed aneurysms had the IVUS appearance of a true or pseudoaneurysm. Instead, most angiographically diagnosed aneurysms had the morphology of complex plaques or normal segments with adjacent stenoses.

Intravascular ultrasound assessment of the stenoses location and morphology in the left main coronary artery in relation to anatomic left main length

Eighty-seven left main stenoses were evaluated by angiography and intravascular ultrasound. Intravascular ultrasound analysis included left main length (bifurcation to ostium), stenosis location, stenosis length, stenosis external elastic membrane, lumen, plaque & media cross-sectional area (CSA), plaque burden (plaque & media/external elastic membrane CSA), calcium arc, calcium length, eccentricity, and remodeling index (stenosis/reference external elastic membrane CSA). Long anatomic left main arteries (length > or =10 mm, n = 43) were compared with short anatomic left main arteries (length <10 mm, n = 44) regarding stenosis location. Ostial (proximal third of left main artery) (n = 32) and nonostial (midthird and distal third) stenoses (n = 55) were compared regarding stenosis morphology. Short anatomic left main arteries developed stenoses more frequently near the ostium (ostium 55%, bifurcation 38%). Conversely, long anatomic left main arteries developed stenoses more frequently near the bifurcation (ostium 18%, bifurcation 77%, p = 0.001). Ostial left main stenoses were more common in women (44% vs 20%, p = 0.02), had larger lumen area (6.2 +/- 2.2 vs 4.6 +/- 2.3 mm(2), p = 0.002), less plaque burden (62 +/- 15% vs 80 +/- 9%, p <0.0001), less calcification (arc = 78 +/- 65 degrees vs 195 +/- 101 degrees, p <0.0001), and more negative remodeling (remodeling index = 0.87 +/- 0.19 vs 1.01 +/- 0.21, p = 0.005) than nonostial left main stenoses. Most ostial left main stenoses were categorized as eccentric (97% vs 76%, p = 0.01). Short and long left main arteries develop stenoses at different locations. Stenosis morphology was significantly different in these 2 locations.

PhaR, a protein of unknown function conserved among short-chain-length polyhydroxyalkanoic acids producing bacteria, is a DNA-binding protein and represses Paracoccus denitrificans phaP expression in vitro

A putative regulatory protein, PhaR, which was identified in the polyhydroxyalkanoic acid synthetic locus (phaZCPR) in Paracoccus denitrificans, was investigated. The PhaR protein purified from a recombinant Escherichia coli was estimated to be 22 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, being consistent with the mass calculated from the nucleotide sequence. The molecular mass was determined to be 93 kDa by size-exclusion chromatography, suggesting that the protein formed a tetramer. A gel mobility shift assay showed that PhaR specifically bound to the intergenic region of phaC--phaP. In a cell-free protein synthesis system using E. coli S30 extract, the expression of the phaP gene was repressed by the addition of purified PhaR. These results suggest that PhaR is a DNA-binding protein and may play a role in the regulation of phaP gene expression.

PhaR, a protein of unknown function conserved among short-chain-length polyhydroxyalkanoic acids producing bacteria, is a DNA-binding protein and represses Paracoccus denitrificans phaP expression in vitro

A putative regulatory protein, PhaR, which was identified in the polyhydroxyalkanoic acid synthetic locus (phaZCPR) in Paracoccus denitrificans, was investigated. The PhaR protein purified from a recombinant Escherichia coli was estimated to be 22 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, being consistent with the mass calculated from the nucleotide sequence. The molecular mass was determined to be 93 kDa by size-exclusion chromatography, suggesting that the protein formed a tetramer. A gel mobility shift assay showed that PhaR specifically bound to the intergenic region of phaC--phaP. In a cell-free protein synthesis system using E. coli S30 extract, the expression of the phaP gene was repressed by the addition of purified PhaR. These results suggest that PhaR is a DNA-binding protein and may play a role in the regulation of phaP gene expression.

Analysis of mutational effects of a polyhydroxybutyrate (PHB) polymerase on bacterial PHB accumulation using an in vivo assay system

Polymerase is a central enzyme involved in the biosynthesis of polyhydroxybutyrate (PHB), a well-known bacterial biodegradable polyester. In this study, we have established an in vivo assay system to analyze mutational effects of Ralstonia eutropha polymerase (termed PhbC(Re)) on the level of PHB accumulation in recombinant strains of Escherichia coli. This in vitro evolution system consists of a polymerase chain reaction-mediated random mutagenesis and two assay procedures, a plate assay using a PHB-staining dye and a high-pressure liquid chromatographic assay based on the converting reaction from PHB to crotonic acid. The distribution pattern of the PHB accumulation level of the mutant population using 378 clones arbitrarily selected, suggested that the present level of PhbC(Re) is high and well-optimized. It is noteworthy that many of the amino acid substitutions affecting the PHB accumulation occurred in the conserved positions or regions within an 'alpha/beta hydrolase fold' which is commonly found among hydrolytic enzymes. From a good correlation with the level of PHB accumulation, an activity estimation of the PhbC(Re) would be efficiently achieved by monitoring the level of PHB accumulation using the in vivo assay system established here.

Identification of the intracellular polyhydroxyalkanoate depolymerase gene of Paracoccus denitrificans and some properties of the gene product

Paracoccus denitrificans degraded poly(3-hydroxybutyrate) (PHB) in the cells under carbon source starvation. Intracellular poly(3-hydroxyalkanoate) (PHA) depolymerase gene (phaZ) was identified near the PHA synthase gene (phaC) of P. denitrificans. Cell extract of Escherichia coli carrying lacZ--phaZ fusion gene degraded protease-treated PHB granules. Reaction products were thought to be mainly D(--)-3-hydroxybutyrate (3HB) dimer and 3HB oligomer. Diisopropylfluorophosphonate and Triton X-100 exhibited an inhibitory effect on the degradation of PHB granules. When cell extract of the recombinant E. coli was used, Mg(2+) ion inhibited PHB degradation. However, the inhibitory effect by Mg(2+) ion was not observed using the cell extract of P. denitrificans.

Longitudinal plaque redistribution during stent expansion

The purpose of this study was to clarify the 3-dimensional behavior of plaque during coronary stent expansion. Serial intravascular ultrasound (IVUS) studies, preintervention, and poststenting were evaluated in 32 patients treated with a single-balloon expandable tubular stent. External elastic membrane (EEM), lumen, stent, and plaque + media cross-sectional area were measured at 1-mm intervals through the entire stent as well as proximal and distal reference segments 5 mm from the stent edge. Volumetric calculations were based on Simpson's rule. Overall, the plaque + media volume through the entire lesion did not change during stent expansion (218 +/- 51 vs 217 +/- 47 mm3, p = 0.69). However, EEM and lumen volume increased significantly (EEM volume, 391 +/- 84 vs 448 +/- 87 mm3 [p < 0.0001]; lumen volume, 173 +/- 52 vs 231 +/- 54 mm3 [p < 0.0001]). The change in lumen volume correlated strongly with the change in EEM volume (r = 0.85, p < 0.0001), but poorly with the change in plaque + media volume (r = 0.37, p = 0.03). Plaque + media volume decreased in the midstent zone (59 +/- 14 vs 53 +/- 11 mm3, p = 0.0005), and increased in the distal stent zone (40 +/- 11 vs 44 +/- 9 mm3, p = 0.003), but did not change in either the proximal stent zone or reference segments. The mechanism of stent expansion is a combination of vessel stretch and plaque redistribution, translating disease accumulation from the midstent zone to the distal stent zone.

Coronary calcification: assessment by intravascular ultrasound imaging

The role of intralesional coronary calcification is not only an important prognostic factor with respect to interventions, but can be extremely important with respect to diagnostic classification of lesion subsets. Intravascular ultrasound details the relationship between plaque and vessel wall in real time throughout the coronary arterial tree. This provides the opportunity to exactly define not only the quantity but also the distribution of calcium within the vessel wall. This is particularly important from a diagnostic standpoint, as plaque-containing calcification can often lead to ambiguous or erroneous angiographic information. Being able to classify different plaque substructures with intravascular ultrasound can help not only to clarify the ambiguous angiogram but delineate the exact nature of luminal encroachment. From a treatment standpoint, the identification of calcification patterns, particularly those on the superficial intimal surface, can alert the operator to change the compliance prior to definitive therapy. High-speed rotational atherectomy is a technique that provides significant de-calcification in preparation for optimizing the stent geometry within such lesion subsets. Although electron beam computed tomography can accurately locate calcification patterns within the coronary tree in a non-invasive manner, it's often difficult to know the extent of calcification and the relationship to fibrofatty plaques. Intravascular ultrasound albeit invasive, provides the opportunity to delineate these plaque substructures and potentially identify lesion subsets that may have an important natural history in the development of coronary atherosclerosis.

[Copper supplement with cocoa for copper deficiency in patients with long-term enteral nutrition]

Copper deficiency (normal serum copper level: 78-136 micrograms/dl) has been reported in patients with long-term enteral nutrition, caused by a copper deficit in enteral nutrition. Occasionally, this leads to anemia and leukopenia. We used Hershey's pure cocoa that is rich in copper (content 3.8 mg/cocoa 100 g) for copper deficiency. A total of 86 (40 men and 46 women, mean age 69 years) patients on enteral nutrition were studied. The primary diseases were cerebral vascular disease in 71 patients, neurological disease in 5 and others in 10. Those who showed serum copper levels of 20 micrograms/dl or less (N = 8) were given 30-45 g of cocoa (copper content 1.14-1.71 mg) per day for about 40 days. Among them, two patients could not continue because of vomiting and diarrhea and were excluded from this study. Mean serum copper levels increased from 8.7 +/- 6.2 to 99.0 +/- 25.4 micrograms/dl (N = 6). Those who showed serum copper levels 20-77 mg/dl (N = 31) were given 10 g of cocoa (copper content 0.38 mg) per day for about 40 days. When mean serum copper levels increased from 50.5 +/- 19.3 to 89.0 +/- 12.9 micrograms/dl with cocoa administration, anemia and neutropenia caused by copper deficiency showed a tendency to improve. After completing the study period, cocoa was reduced to 5 g (copper content 0.19 mg) per day in 23 patients. The mean serum copper levels increased from 90.7 +/- 10.4 to 100.6 +/- 17.1 micrograms/dl for about 100 days. Recently, the amount of daily copper requirement for adults has been reported to be 1.28-2.5 mg per day. We showed that 10 g of cocoa (0.6 mg total copper: 0.38 mg in cocoa and 0.22 mg in other nutrients) is sufficient to treat copper deficiency, and 5 g of cocoa (0.37 mg total copper: 0.19 mg in cocoa and 0.18 mg in other nutrients) is enough to maintain the normal level of serum copper in patients with long-term enteral nutrition.

Analyses of a polyhydroxyalkanoic acid granule-associated 16-kilodalton protein and its putative regulator in the pha locus of Paracoccus denitrificans

The polyhydroxyalkanoic acid (PHA) granule-associated 16-kDa protein (GA16 protein) of Paracoccus denitrificans was identified, and its corresponding gene was cloned and analyzed at the molecular level. The N-terminal amino acid sequence of GA16 protein revealed that its structural gene is located downstream from the PHA synthase gene (phaCPd) cloned recently (S. Ueda, T. Yabutani, A. Maehara, and T. Yamane, J. Bacteriol. 178:774-779, 1996). Gene walking around phaCPd revealed two new open reading frames (ORFs) possibly related to PHA synthesis, one of which was the phaPPd gene, encoding GA16 protein, and the other was the phaRPd gene, encoding a protein that is putatively involved in the regulation of the expression of phaPPd. Overproduction of PhaPPd was observed in Escherichia coli carrying phaPPd, but the overproduction was not observed in the presence of phaRPd. Coexpression of phaPPd and PHA biosynthesis genes in E. coli caused increases in both the number of poly-(3-hydroxybutyric acid) (PHB) granules and PHB content and caused decreases in both the size of the granules and the molecular weight of PHB. GA16 protein was considered a phasin protein. The phaRPd gene had significant similarities to stdC, a possible transcriptional factor of Comamonas testosteroni, as well as to other ORFs of unknown function previously found in other PHA-synthetic bacteria.

Transcatheter embolization of arteriovenous malformations in Cowden disease

A patient with Cowden disease and multiple arteriovenous malformations (AVMs) that resulted in high output heart failure is described. Cowden disease is a familial syndrome characterized by endodermal, mesodermal and ectodermal dysplasia causing benign and malignant tumors of the skin, breast, gastrointestinal tract, and thyroid gland. Our patient had gastrointestinal polyposis, a right renal tumor, a left lung tumor, an adenomatous goiter, and typical dermatologic findings such as facial papules, acral keratosis, gingival papillomatosis and hemangiomas. AVMs were observed in the pelvis, cervical vertebra, liver, and right supraclavicular area. Transcatheter embolization was performed 7 times for the pelvic AVMs, but the effect decreased with repetition and the patient died of heart failure 2 years after the first embolization. The serum levels of tissue plasminogen activator (t-PA), platelet-derived growth factor (PDGF), hepatocyte growth factor (HGF), vascular endothelial growth factor (VEGF), and transforming growth factor beta1 were high, suggesting that these angiogenic molecules may play a role in the pathogenesis of AVMs in Cowden disease.

Gene dosage effects on polyhydroxyalkanoates synthesis from n-alcohols in Paracoccus denitrificans

Putative promoters of polyhydroxyalkanoate (PHA)-synthetic genes of Paracoccus denitrificans were identified. Gene dosage effects for PHA synthesis were investigated in recombinants of P. denitrificans with increased expression levels of each PHA synthetic enzyme. In the cultivation of shake flasks using ethanol or n-pentanol as carbon source, a self-cloning recombinant of the phaC-encoding PHA synthase showed the highest contents [(g PHA). (g total biomass)-1] and the highest rates of PHA accumulation [(g PHA). (g residual biomass)-1. h-1] among these recombinants. The PHA content and PHA accumulation rate (g PHA/g residual biomass. h-1) of the self-cloning recombinant was 2 and 2.7 times higher, respectively, than that of the wild strain. This result strongly suggests that the step of PHA synthase is limited in in vivo PHA synthesis from n-pentanol via 3-ketovaleryl-CoA through beta-oxidation, and from ethanol via acetyl-CoA. Studies on fed-batch cultures keeping the alcohol concentration constant (0.02%) in a 5-L bioreactor showed that the ability of PHA biosynthesis was improved by the gene dosage of PHA synthase, although the growth rate of cells during the growth-associated PHA synthesis phase was retarded. The molecular weight of the polymer isolated from the strain, dosed by the PHA synthase gene, was lower than that of the polymer from the wild strain, indicating that the amount of PHA synthase in vivo affects the molecular weight of the polymer.

Molecular analysis of the poly(3-hydroxyalkanoate) synthase gene from a methylotrophic bacterium, Paracoccus denitrificans

A 3.6-kb EcoRI-SalI fragment of Paracoccus denitrificans DNA hybridized with a DNA probe carrying the poly(3-hydroxyalkanoate) (PHA) synthase gene (phaC) of Alcaligenes eutrophus. Nucleotide sequence analysis of this region showed the presence of a 1,872-bp open reading frame (ORF), which corresponded to a polypeptide with a molecular weight of 69,537. Upstream of the ORF, a promoter-like sequence was found. Escherichia coli carrying the fusion gene between lacZ and the ORF accumulated a level of poly(3-hydroxybutyrate) that was as much as 20 wt% of the cell dry weight in the presence of beta-ketothiolase and acetoacetylcoenzyme A reductase genes of A. eutrophus. The ORF was designated phaCPd. A plasmid vector carrying the phaCPd'-'lacZ fusion gene downstream of the promoter-like sequence expressed beta-galactosidase activity in P. denitrificans. When a multicopy and broad-host-range vector carrying the ORF along with the promoter-like sequence was introduced into P. denitrificans, the PHA content in the cells increased by twofold compared with cells carrying only a vector sequence.

Analysis of beta-ketothiolase and acetoacetyl-CoA reductase genes of a methylotrophic bacterium, Paracoccus denitrificans, and their expression in Escherichia coli

The beta-ketothiolase gene (phaA) and acetoacetyl-CoA reductase gene (phaB) were isolated from Paracoccus denitrificans. Nucleotide sequence analysis showed that they encoded proteins of 391 amino acids with a molecular mass of 40,744 Da and of 242 amino acids with a molecular mass of 25,614 Da, respectively. The predicted gene products exhibited high amino acid identities with those from other bacteria: 64.4-74.0% for the phaA gene product and 47.6-80.6% for the phaB gene product, respectively. Both genes were co-transcribed in a recombinant Escherichia coli. In addition, promoter activity was detected upstream of the phaA gene. Hence, the two genes are organized as an operon, phaA-phaB, in P. denitrificans. NADH was preferred to NADPH as a cofactor of acetoacetyl-CoA reductase.