ST-segment elevation associated with allergic reaction to echocardiographic contrast agent administration

We report a case of an allergic reaction after the administration of an echocardiographic contrast agent which resulted in ST-segment elevation. Hypersensitivity and allergic reactions are known causes of acute cardiovascular events. However, only limited reports are available which suggest the exact mechanism of the occurrence of angina or myocardial infarction during severe allergic reactions. In our case, through invasive imaging (coronary angiography and IVUS) we have shown for the first time a transient coronary spasm in the absence of intra-coronary thrombus and only minimal neointimal hyperplasia.     

SUMOylation and PARylation cooperate to recruit and stabilize SLX4 at DNA damage sites

SUMOylation plays important roles in the DNA damage response. However, whether it is important for interstrand crosslink repair remains unknown. We report that the SLX4 nuclease scaffold protein is regulated by SUMOylation. We have identified three SUMO interaction motifs (SIMs) in SLX4, mutating all of which abrogated the binding of SLX4 to SUMO-2 and covalent SLX4 SUMOylation. An SLX4 mutant lacking functional SIMs is not recruited to PML nuclear bodies nor stabilized at laser-induced DNA damage sites. Additionally, we elucidated a novel role for PARylation in the recruitment of SLX4 to sites of DNA damage. Combined, our results uncover how SLX4 is regulated by post-translational modifications.     

Activating and inhibitory Fcγ receptors in rheumatoid arthritis: from treatment to targeted therapies

Fcγ receptors (FcγRs) bind the constant Fc region of IgG molecules. IgG/antigen-containing immune complexes elicit a variety of effector functions in cells that express activating FcγRs. Because activating FcγRs are present on cells from the innate immune system, such as dendritic cells, monocytes/macrophages and granulocytes, these IgG receptors form a crucial link between the innate and the acquired immune systems. Recently, the ability to detect the inhibitory FcγRIIb on cells has indicated an imbalance between activating and inhibitory FcγRs in rheumatoid arthritis. This progress offers an opportunity to study modulation of FcγR balance and could stimulate development of FcγR-directed immunotherapy.     

Control of Anthocyanin Synthesis in PETUNIA HYBRIDA by Multiple Allelic Series of the Genes An1 and An2

A mutable allele of the An1 locus in Petunia hybrida has given rise to a multiple series of stable derivative alleles. Anthocyanin concentration in mature flowers of these mutants (an1^{+/ p}/an1) decreases from the wild-type red to the recessive white in a continuous series. Anthocyanin composition changes regularly: the ratio of peonidin to cyanidin is 3.5 for an an1^+/+/ an1 and 1.2 for an an1^+/p5/an1 mutant. Analysis of anthocyanins during flower development indicates that these differences in composition are due to the specific state of the An1 locus and not to anthocyanin concentration. Anthocyanin concentration in flowers of the allelic series for An1 correlates with the activity of the enzymes UDP-glucose: flavonoid-3-O-glucosyltransferase and SAM: anthocyanin-3'- O-methyltransferase. The same correlations were found for members of a comparable allelic series at the An2 locus. The possibility that the correlation between the enzyme activities is due to the occurrence of a multienzyme complex is discussed.     

Polyamine levels in petunia genotypes with normal and abnormal floral morphologies

We characterized the polyamine pathway in Petunia hybrida genotypes that were either wild type or that had been identified as having altered floral morphology. Analysis of four normal morphology lines revealed two patterns of endogenous levels of putrescine and arginine decarboxylase: two with higher levels of putrescine, two with lower levels of putrescine. Analysis of F1 and backcross progeny between high putrescine and low putrescine strains is consistent with their differences being due to a dominant allele for low putrescine content and arginine decarboxylase activity. Four Petunia mutants with floral morphology changes were also screened. One of these mutants, alf, showed high levels of putrescine and high levels of arginine decarboxylase late in development; these high levels were found whether the alf line was present in either of the two types of normal morphology genetic backgrounds that had been characterized.     

Regulation of gene action in Petunia hybrida: Unstable alleles of a gene for flower colour

Summary In a progeny of a selfed individual of the dark red-flowered cultivar Roter Vogel some white-flowered plants appeared as the result of a mutation of the genetic factor Anl involved in anthocyanin synthesis. The white flowers of these plants had red spots owing to back-mutations in the dermal cells of the young corolla.Owing to a striking unstability of the new allele of Anl, a number of mutants originated which differ mutually in the frequency of reversion, which expressed itself in the very substantial differences in the spot density of the limb of the corolla. Between a mean number of less than one spot per cm² of the limb and a mean number of over 10.000 spots/cm², a series of transitions was found.The reversions did not remain restricted to the young epidermis but also occurred in sporogenous tissues. This resulted in the appearance of selfcoloured red descendants of plants with red-spotted white flowers. There is a positive correlation between the spot density of the parent plants and the percentage of plants with completely red corollas.The red spots on the corolla usually have the same colour as the wild type (Roter Vogel), but occasionally mutants occur with paler spots, the colour varying from a very pale pink to a red nearly as deep as in the wild type. The selfcoloured descendants of such mutants also show this colour variation from pale pink to red.On the grounds of these observations a theory was formulated which postulates that the Anl locus consists of a structural gene responsible for an enzyme active during anthocyanin synthesis and a regulatory element built up from intermediate repetitive DNA. This regulatory element in turn is built up of two components, one of which, the mutator, decides the activation of the structural gene while the other, the expressor, modifies the rate of activation. The mutations must be considered representative of larger or smaller deletions within one or both of these components. Reversions are the result of the restoration of the deletions by means of an amplification of the repetitive DNA in dividing cells of the developing flower buds.