Lycopene-Family Carotenoids Confer Thermostability on Photocomplexes from a New Thermophilic Purple Bacterium.

Blastochloris tepida is a newly described thermophilic purple bacterium containing bacteriochlorophyll b. Using purified light-harvesting 1 reaction center (LH1-RC) core complexes from Blc. tepida, we compared the biochemical, spectroscopic, and thermal denaturation properties of these complexes with those of its mesophilic counterpart, Blc. viridis. Besides their growth temperature optima, a striking difference between the two species was seen in the carotenoid composition of their LH1-RC complexes. The more thermostable Blc. tepida complex contained more carotenoids with longer conjugation lengths (n > 9), such as lycopenes (n = 11), and had a total carotenoid content significantly higher than that of the Blc. viridis complex, irrespective of the light intensity used for growth. The thermostability of LH1-RCs from both Blc. tepida and Blc. viridis decreased significantly in cells grown in the presence of diphenylamine, a compound that inhibits the formation of highly conjugated carotenoids. In contrast to the thermophilic purple bacterium Thermochromatium tepidum, where Ca2+ is essential for LH1-RC thermostability, Ca2+ neither was present in nor had any effect on the thermostability of the Blc. tepida LH1-RC. These results point to a mechanism that carotenoids with elongated conjugations enhance hydrophobic interactions with proteins in the Blc. tepida LH1-RC, thereby allowing the complexes to withstand thermal denaturation. This conclusion is bolstered by a structural model of the Blc. tepida LH1-RC and is the first example of photocomplex thermostability being linked to a carotenoid-based mechanism.

Coexistence of keloids and pilomatricoma in a patient with Rubinstein-Taybi syndrome.

Rubinstein-Taybi syndrome (RTS) is an autosomaldominant hereditary disease, which contains many skeletal and organ anomalies as well as mental retardation. Although high incidence of keloids in RTS is known, it is difficult to find a detailed report on the clinical features of keloids. In the following letter, we report an RTS patient fulfilling diagnostic criteria whosuffered from both keloids and pilomatricoma. We also performed a literature search, which identified the possible involvement of the Wnt/ß-catenin signaling pathway in the pathogenesis of these two skin lesions.

Involvement of the Tyr kinase/JNK pathway in carbachol-induced bronchial smooth muscle contraction in the rat.

BACKGROUND: Tyrosine (Tyr) kinases and mitogen-activated protein kinases have been thought to participate in the contractile response in various smooth muscles. The aim of the current study was to investigate the involvement of the Tyr kinase pathway in the contraction of bronchial smooth muscle. METHODS: Ring preparations of bronchi isolated from rats were suspended in an organ bath. Isometric contraction of circular smooth muscle was measured. Immunoblotting was used to examine the phosphorylation of c-Jun N-terminal kinasess (JNKs) in bronchial smooth muscle. RESULTS: To examine the role of mitogen-activated protein kinase(s) in bronchial smooth muscle contraction, the effects of MPAK inhibitors were investigated in this study. The contraction induced by carbachol (CCh) was significantly inhibited by pretreatment with selective Tyr kinase inhibitors (genistein and ST638, n = 6, respectively), and a JNK inhibitor (SP600125, n = 6). The contractions induced by high K depolarization (n = 4), orthovanadate (a potent Tyr phosphatase inhibitor) and sodium fluoride (a G protein activator; NaF) were also significantly inhibited by selective Tyr kinase inhibitors and a JNK inhibitor (n = 4, respectively). However, the contraction induced by calyculin-A was not affected by SP600125. On the other hand, JNKs were phosphorylated by CCh (2.2 ± 0,4 [mean±SEM] fold increase). The JNK phosphorylation induced by CCh was significantly inhibited by SP600125 (n = 4). CONCLUSION: These findings suggest that the Tyr kinase/JNK pathway may play a role in bronchial smooth muscle contraction. Strategies to inhibit JNK activation may represent a novel therapeutic approach for diseases involving airway obstruction, such as asthma and chronic obstructive pulmonary disease.

Anti-citrullinated protein antibody-positive rheumatoid arthritis associated with RS3PE syndrome-like symptoms and an elevated serum vascular endothelial growth factor level in a patient with myasthenia gravis.

A 73-year-old man with a history of myasthenia gravis (MG) was diagnosed with rheumatoid arthritis (RA) based on a history of polyarthritis and positivity for anti-citrullinated protein antibodies (ACPA). He presented with a high level of serum vascular endothelial growth factor (VEGF) and RS3PE syndrome-like pitting edema in the extremities, which improved following treatment with low-dose prednisolone. This is an interesting case of ACPA-positive RA associated with RS3PE syndrome-like pitting edema and a high VEGF level.