Niche adaptation and genome expansion in the chlorophyll d-producing cyanobacterium Acaryochloris marina

Acaryochloris marina is a unique cyanobacterium that is able to produce chlorophyll d as its primary photosynthetic pigment and thus efficiently use far-red light for photosynthesis. Acaryochloris species have been isolated from marine environments in association with other oxygenic phototrophs, which may have driven the niche-filling introduction of chlorophyll d. To investigate these unique adaptations, we have sequenced the complete genome of A. marina. The DNA content of A. marina is composed of 8.3 million base pairs, which is among the largest bacterial genomes sequenced thus far. This large array of genomic data is distributed into nine single-copy plasmids that code for >25% of the putative ORFs. Heavy duplication of genes related to DNA repair and recombination (primarily recA) and transposable elements could account for genetic mobility and genome expansion. We discuss points of interest for the biosynthesis of the unusual pigments chlorophyll d and α-carotene and genes responsible for previously studied phycobilin aggregates. Our analysis also reveals that A. marina carries a unique complement of genes for these phycobiliproteins in relation to those coding for antenna proteins related to those in Prochlorococcus species. The global replacement of major photosynthetic pigments appears to have incurred only minimal specializations in reaction center proteins to accommodate these alternate pigments. These features clearly show that the genus Acaryochloris is a fitting candidate for understanding genome expansion, gene acquisition, ecological adaptation, and photosystem modification in the cyanobacteria.     

Cold exposure and left ventricular diastolic performance in coronary artery disease

It is known that cold exposure is accompanied by coronary artery vasoconstriction and ischemia in patients with coronary artery disease (CAD). The aim of the present study was to evaluate the response of left ventricular (LV) diastolic and systolic functions, estimated by means of Doppler echocardiography, to cold pressor test (CPT) in patients with CAD. Twenty-five male patients (mean age 50.8 +/- 8.1 years) with documented CAD underwent CPT with Doppler echocardiographic assessment of LV diastolic and systolic functions. According to the development of ischemic response to CPT, all patients were divided into 2 groups: group 1, 10 patients with ischemia and group 2, 15 patients without ischemia during CPT. Cold exposure caused significant increase in blood pressure with no changes in heart rate in all CAD patients. Patients with signs of ischemia during cold exposure had lower transmitral flow velocity during early filling (p < 0.001), prolonged isovolumic relaxation time (p < 0.04), shortened deceleration time of early transmitral flow velocity (p < 0.001), and higher values of Doppler-derived index of myocardial performance (p < 0.0001) than those without ischemic response to CPT. Cold exposure in CAD patients through stimulating of vasoconstriction and ischemia was associated with derangements in LV myocardial performance, manifested by delayed relaxation, impaired stiffness, and reduced contractility.     

Ectasia and severe atherosclerosis: relationships with chlamydia pneumoniae, helicobacterpylori, and inflammatory markers

To date, there has been no convincing evidence for an association between Chlamydia pneumoniae or Helicobacter pylori and ectasia. In this case-control study, we have investigated the association of H. pylori and C. pneumoniae seropositivity with ectasia, severe coronary atherosclerosis, and normal vessels, which were so classified by coronary angiography. We have also evaluated the influence of these infections on inflammatory markers such as high-sensitive C-reactive protein (hsCRP) and interleukin 6 (IL-6). Of the 796 patients undergoing coronary angiography for suspected ischemic heart disease, 244 patients were recruited. Of these, 91 had normal vessels, 88 had 3 or more obstructed vessels, and 65 had ectatic vessels without atherosclerosis. Eighty-seven atherosclerotic patients (98.9%) were positive for C. pneumoniae IgG, as were 64 ectatic patients (98.5%) and 76 controls (83.5%) (P < 0.001). Forty-two atherosclerotic patients (47.7%) were positive for C. pneumoniae IgM, as were 43 ectatic patients (66.2%) and 43 controls (47.3%) (P = 0.036). Seventy-two atherosclerotic patients (81.8%) were positive for H. pylori IgA, as were 26 ectatic patients (40.0%) and 44 controls (48.4%) (P < 0.001). High-sensitive CRP levels were significantly higher in ectatic patients (5.639 mg/L) than in controls (4.390 mg/L) (P = 0.032), and IL-6 levels were significantly higher in atherosclerotic patients (33.92 U/L) than in controls (14.01 U/L) (P < 0.001). Interleukin-6 levels were higher in H. pylori seropositive patients, and hsCRP levels were higher in C. pneumoniae seropositive patients, when compared with seronegatives. We suggest that, as in atherosclerosis, C. pneumoniae infection is related to ectasia, with raised CRP levels.     

Preliminary study showing the relationship between platelet fibronectin, sialic acid, and ADP-induced aggregation levels in coronary heart disease.

Several studies indicate that thrombosis plays an important role in the pathogenesis of coronary heart disease (CHD). Fibronectin is a multifunctional protein in plasma, other body fluids, and cell surface and plays an important role in platelet functions, including mediation of cell-cell and cell-surface interactions. Sialic acid is a regular constituent of glycoproteins and gangliozides in the outer cell membrane of mammalian cells. Therefore, the sialic acid content of platelets, which are characterized by their ability to aggregate with each other, can be important in leading to thrombus formation. In this study, platelet fibronectin, sialic acid-, and adenosine diphosphate (ADP)-induced platelet aggregation levels were determined in patients with CHD. Platelet sialic acid concentrations were determined by Warren's method. Platelet aggregation tests with ADP in platelet-rich plasma (PRP) were analyzed by use of an aggregometer. Platelet homogenate fibronectin levels were determined by ELISA. Total protein levels were determined by Lowry method. Our results indicate that, in patients with no vessel disease (patients with no obstructed vessel but suffering from chest pain, like angina pectoris) platelet fibronectin levels were significantly lower than the total of the other patients (patients with 1, 2, or 3 obstructed coronary vessels) (p<0.05). Sialic acid levels in patients with no vessel disease were significantly lower than the total of the patient group (p<0.05). There was significant (+) correlation between platelet aggregation, platelet fibronectin, platelet sialic acid, and severity of disease (p<0.05). Our preliminary findings suggest that, especially platelet fibronectin levels potentially represent a pathogenic factor for CHD.     

Transcatheter closure of congenital coronary arterial fistulas in adults

OBJECTIVES: We have described our experience with transcatheter occlusion of congenital coronary arterial fistulas in adults. METHODS: Six symptomatic patients, mean aged 41+/-12 years (four men, two women) underwent transcatheter occlusion of fistulas. All had chest pain or dyspnea on exertion. Four of the patients had single fistula. Two of the patients had multiple fistulas. The fistulas originated from the left anterior descending coronary artery in four patients, and from the circumflex artery in two. They all drained into the pulmonary trunk. Graft stenting was used in two patients who had multiple fistulas, and coils in four who had a single fistula. The coils were implanted through a microcatheter, which was passed through a JL 4 8F guiding catheter. RESULTS: Coils were used to completely occlude fistulas. Two 3.0x20 mm coronary graft stents were deployed in the coronary arteries to occlude the fistulas. The procedures were uncomplicated. At follow up, all patients underwent coronary angiography, and one of the patients with coil embolization and one of the patients with graft stenting had small residual flow. Patient's chest pain or dyspneas have resolved after the procedure. CONCLUSION: Transcatheter closure in adults of congenital coronary fistulas with graft stents and coils are safe and effective, and can be regarded as an acceptable alternative to surgery.     

Prevalence and significance of MEFV gene mutations in patients with gouty arthritis

Gouty arthritis is a chronic erosive autoinflammatory disease. Pyrin has anti-inflammatory effects in the regulation of inflammasome and is encoded by the MEFV gene. The relationship between different rheumatic diseases and the MEFV gene mutations was demonstrated. The aim of this study was to determine the frequency of MEFV gene mutations in patients with gouty arthritis and identify a possible correlation with disease phenotype. Ninety-three patients with gouty arthritis and 102 healthy controls, compatible with age, gender and ethnicity, were included in the study. MEFV gene mutations were investigated by PCR method. Out of 93 patients with gouty arthritis, 36 (38.7 %) showed MEFV gene mutations carriage, whereas 20.6 % in healthy control group. Distribution of mutations identified in patients with gouty arthritis was as; R202Q in 18 (19.3 %), E148Q in 5 (5.4 %), K695R in 4 (4.3 %), M680I in 2 (2.1 %), V726A in 2 (2.1 %), P369S in 2 (2.1 %), R408Q in 2 (2.1 %), M694 V in 1 (1.1 %), respectively. Three patients were identified with compound heterozygosity. Distribution of MEFV gene mutations carriage in healthy controls was; E148Q in 11 (10.7 %), M694 V in 2 (1.9 %), M694I in 1 (0.9 %), M680I in 2 (1.9 %), V726A in 1 (0.9 %), A744S in 1 (0.9 %), K695R in 2 (1.9 %), and P369S in 1 (0.9 %) patients, respectively. Higher MEFV gene mutations carrier frequency was observed in patients with gouty arthritis, compared with the control group (p = 0.009). Heterozygous R202Q was the most common mutation detected in patients with gouty arthritis, while heterozygous E148Q in healthy control group. Statistically significant difference was not detected between clinical findings of gouty arthritis and the MEFV gene mutations (p > 0.05). We determined higher prevalence of MEFV gene mutations in patients with gouty arthritis compared with the healthy control group. The most frequently detected mutation was heterozygous R202Q, whereas E148Q in healthy controls. High carriage rates of MEFV gene mutations in gouty arthritis suggest that it may play an important role in the pathogenesis of the disease and predisposition to the disease.     

P Wave Amplitude and Duration may Predict Immediate Recurrence of Atrial Fibrillation After Internal Cardioversion

Background: Although internal cardioversion (IC) for atrial fibrillation (AF) is effective at restoring sinus rhythm, immediate recurrence (IR) of AF after IC is a major and largely unpredictable clinical problem. The purpose of the study was to determine the role of P wave duration and amplitude in prediction of IR of AF after IC. Forty‐five consecutive patients undergoing IC for chronic AF were evaluated. Material and Methods: After successful IC, 1‐minute ECG recording was obtained in all patients. P wave duration and amplitude in Lead II and V₁ were measured using computer. Forty patients (88%) had successful IC. Thirteen patients experienced IR of AF within 1 minute of restoring sinus rhythm. Results and Conclusion: As a result, the incidence of IR of AF after IC was higher in the patients with shorter P wave amplitude (for lead II P < 0.01 , for V₁P < 0.01 ) and larger P wave duration (for lead II P < 0.01 , for V₁P < 0.05 ).     

The role of angiotensin converting enzyme genotype in coronary artery ectasia

Coronary artery ectasia (CAE) is characterised by irregular, diffuse, saccular, or fusiform dilatation of the coronary arteries. Although the underlying mechanisms are not fully understood, CAE is considered to be an original form of vascular remodelling in response to atherosclerosis. However, it is not clear why some patients develop CAE while most do not. Experimental data suggest that activation of the renin angiotensin system may lead to an increased inflammatory response in the vessel wall or to an activation of matrix metalloproteinases. In addition, an insertion/deletion (ID) polymorphism of angiotensin converting enzyme (ACE) has been associated with coronary vascular tone and the development of aneurysms. Accordingly, we hypothesised that the gene polymorphism of ACE may be a potential factor influencing the genesis of CAE. We retrospectively evaluated 112 patients who underwent coronary angiography. ACE ID genotype was determined in two groups of patients. Group 1 consisted of 56 patients who were found to have CAE. Group 2 consisted of 56 patients with significant coronary artery disease (CAD) (> 50% stenosis in any of the major epicardial coronary arteries or their branches) but without any evidence of coronary ectasia. Polymerase Chain Reaction (PCR) was used to detect ACE genotype. The ratio of DD genotype was found to be greater in group 1 than group in 2 (39% versus 18%, respectively, P < 0.05). When assessed according to the presence of the I allele, it was greater was greater in group 2 than in group 1 (82.1% versus 60.7%, respectively, P < 0.05). The results indicate that an ACE DD genotype may be a risk factor for CAE.