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.     

Exercise BP response in subjects with high-normal BP: exaggerated blood pressure response to exercise and risk of future hypertension in subjects with high-normal blood pressure

OBJECTIVES: This study was designed to assess the clinical usefulness of an exaggerated blood pressure (BP) response to exercise (EBPR) in predicting the development of hypertension from a high-normal state. BACKGROUND: Exaggerated BP response during both dynamic and isometric exercises are associated with increased risk of future hypertension, while the significance of these responses concerning the identification of individuals with high-normal BP who are prone to develop hypertension is unknown. METHODS: The study population comprised a sample of 239 men with high-normal BP (aged 42.3 +/- 5.9 years) who underwent a symptom-limited bicycle ergometer exercise testing at baseline and then were followed for 5.1 years. RESULTS: The Kaplan-Meier survival analysis showed that the subjects in the upper quartile of BP response to exercise had a significantly higher cumulative incidence of hypertension on follow-up than those in the middle two and lower quartiles (log-rank test, p < 0.05). Multivariate analysis using the Cox proportional hazards survival model showed that the EBPR was significantly and independently associated with the risk of developing hypertension after adjustment for some traditional risk factors for hypertension (RR = 2.31, 95% confidence interval = 1.45 to 6.25). CONCLUSIONS: These findings suggest that an EBPR is an important risk factor for new-onset hypertension from a high-normal state and, thus, exercise testing can provide valid information that may help identify individuals with high-normal BP at a greater risk of future hypertension.     

Preheparin serum lipoprotein lipase mass is negatively related to coronary atherosclerosis

In preheparin serum, there exists lipoprotein lipase (LPL) mass with little activity. The clinical significance of this preheparin serum LPL mass (preheparin LPL mass) is unclear. We studied the levels of preheparin LPL mass in patients with coronary atherosclerosis, comparing the results with those in healthy men. We also evaluated the correlation between preheparin LPL mass and the severity of coronary atherosclerosis by comparing with other risk factors such as age, smoking, family history, hypertension, hyperuricemia, diabetes mellitus, total cholesterol, triglyceride, high density lipoprotein-cholesterol and body mass index. The subjects, 70 men presenting with symptoms of coronary artery disease, underwent coronary angiographic examination. Significant narrowness was defined as > or = 75%. Control group comprised 77 men who had annual health checks and showed no abnormal findings. Preheparin LPL mass in the stenosis group was lower than normal coronary group and also than the control group. Multivariate analysis showed that preheparin LPL mass had the highest t-value (-2.53) for the number of lesions among the risk factors listed above. These results suggest that low preheparin LPL mass may be deeply involved in the progression of coronary atherosclerosis.     

Comparative analysis of clinical outcomes after allogeneic bone marrow transplantation versus peripheral blood stem cell transplantation from a related donor in Japanese patients

A reduced incidence of graft versus host disease (GvHD) has been documented among Japanese allogeneic bone marrow transplantation (BMT) patients, as the Japanese are genetically more homogeneous than western populations. To clarify whether this ethnic difference affects the results of allogeneic peripheral blood stem cell transplantation (PBSCT), we conducted a nationwide survey to compare clinical outcomes of allogeneic PBSCT (n = 214) and BMT (n = 295) from a human leucocyte antigen-identical-related donor in Japanese patients. The cumulative incidence of grades II-IV acute GvHD was 37.4% for PBSCT and 32.0% for BMT. The cumulative incidence of extensive chronic GvHD at 1 year was significantly higher after PBSCT than BMT (42% vs. 27%; P < 0.01). The organ involvement patterns of GvHD were different between the two groups. By multivariate analyses, the incidence of chronic GvHD was significantly increased in PBSCT, whereas the stem cell source did not affect the incidence of acute GvHD, transplant-related mortality, relapse or survival. We concluded that Japanese PBSCT patients have an increased risk of chronic GvHD compared with BMT patients, but the incidence of acute GvHD was still lower than in western populations. Thus, the choice of haematopoietic stem cell source should be considered based on data for individual ethnic populations.     

Recurrent pneumonia due to persistent Chlamydia pneumoniae infection

Two cases of recurrent pneumonia due to Chlamydia pneumoniae are described. C. pneumoniae was continuously detected from the nasopharynx in both patients by the polymerase chain reaction and/or culture even with appropriate antibiotic therapy during the first episode. After eradication of C. pneumoniae with long-term macrolide therapy, the respiratory symptoms of both patients completely disappeared and no relapse was observed. These data indicate that new treatment strategies may be necessary to eradicate the organism in patients prone to persistent infection.     

Autocrine regulation of cell proliferation by estradiol and hydroxytamoxifen of transformed mouse Leydig cells in serum-free culture

We have previously reported that the cloned cell line (B-1-A-2) derived from an estrogen-responsive mouse Leydig cell tumor shows an estrogen-dependent enhancement of cell proliferation in medium supplemented with charcoal-dextran-stripped fetal bovine serum. To avoid the involvement of unknown factors present in the serum in the pathway for estrogen-dependent cell growth, the present study was designed to establish a serum-free culture system to which growth factors could be added. To this end, we subcloned B-1 cells from the parental tumor cell line. The proliferation of B-1 cells was markedly stimulated by the addition of 10(-11)-10(-8) M estradiol into the serum-free medium [Eagle's Minimum Essential Medium-Ham's F-12 (1:1, vol/vol) containing 0.2% (wt/vol) BSA]. Epidermal growth factor (0.1-50 ng/ml) or insulin (0.1-50 micrograms/ml) alone or in combination with 10(-8) M estradiol did not affect the proliferation rate of B-1 cells. In contrast, a greater than 10-fold molar excess of 4-hydroxytamoxifen blocked estradiol-induced cell proliferation, while 4-hydroxytamoxifen alone failed to show a stimulatory effect on cell multiplication. Additionally, the conditioned medium collected from estradiol-stimulated cells was found to contain a growth-promoting factor(s) whose activity was not antagonized by 4-hydroxytamoxifen. Nonstimulated cells secreted a significant but low level of the growth-promoting factor. Finally, B-1 cells were found to be estrogen dependent for cell proliferation in BALB/c mice. Their growth was markedly inhibited by the administration of tamoxifen to the host mice. These results indicate that the serum-free culture system presented here is suitable for studying the autocrine mechanisms of cell growth regulated by estrogens as well as triphenylethylene compounds.     

A technique for diagnosis of accessory pathway using the H-H and A-A intervals of the first entrained cycle during ventricular overdrive pacing

Although advancement of succeeding atrial activation by a ventricular extrastimulus (VES) on His refractoriness during supraventricular tachycardia (SVT) has been used as evidence of an accessory pathway (AP), the sensitivity of this method is suboptimal. This study was designed to compare the His-His (H-H) and atrial-atrial (A-A) intervals of the first entrained cycle during ventricular overdrive pacing (VOD) for the diagnosis of AP, in comparison to the conventional VES method. In 55 patients with SVT, a VES was elicited on His refractoriness during SVT. VOD was subsequently performed at cycle lengths 30 to 40 ms shorter than SVT cycle lengths. When the A-A interval became equal to the pacing cycle length after some beats of VOD, the cycle was considered the first entrained cycle and the H-H interval preceding the A-A interval was measured. VES advanced the next atrial activation in 16 patients (52%) with an AP, but in no patient without an AP. The H-H interval of the first entrained cycle was longer than the pacing cycle length by > or =15 ms in all patients with an AP, but was equal to the pacing cycle length in all patients without an AP. The criterion of H-H greater than A-A by > or =15 ms for the first entrained cycle provided higher diagnostic yield for AP compared with the VES method(100% vs 52%, p <0.001). In conclusion, this new criterion reliably diagnoses the presence of an AP in patients with SVT, with higher sensitivity compared with the VES method.