Enhanced Alkaloid Production in Callus Cultures of Heliotropium indicum L and Regeneration of Plantlets

Heliotropium indicum L (Boraginaceae) contains the anticancer pyrrolizidine alkaloid, indicine-N-oxide (INO). To study the yield of INO as a function of plant development, plantlets were regenerated in vitro from nodal and hypocotyl explants and also from hypocotyl callus, on Murashige and Skoog’s (MS) medium supplemented with 1-naphthaleneacetic acid (NAA), 6-benzylaminopurine (BAP), asparagine (Asp) and glutamine (Glu). The regenerated plantlets were rooted on MS supplemented with Glu or gibberellic acid (GA₃). While 5-week-old seedlings showed a high amount of INO (0.12% dry wt) that depleted gradually as the plants attained maturity and flowered, fast growing callus produced a much higher yield of INO (0.32% dry wt). As the callus cultures differentiated into shoots and subsequently into plantlets, the INO content decreased to about 0.2% dry wt. It appears that INO is the primary product of pyrrolizidine alkaloid biosynthetic pathway in rapidly growing meristematic tissue of Heliotropium indicum, later reduced to its alkaloidal base and reallocated to other tissues. The article includes an efficient micropropagation method for Heliotropium indicum.     

Anatomical basis for the mobility of the esophagus: implications for catheter ablation of atrial fibrillation

We present autopsy data from a patient that illustrates the anatomical factors that allow the esophagus to be a mobile structure, especially with respect to the posterior left atrial wall.     

Annexin-V imaging for noninvasive detection of cardiac allograft rejection.

Heart transplant rejection is characterized pathologically by myocyte necrosis and apoptosis associated with interstitial mononuclear cell infiltration. Any one of these components can be targeted for noninvasive detection of transplant rejection. During apoptotic cell death, phosphatidylserine, a phospholipid that is normally confined to the inner leaflet of cell membrane bilayer, gets exteriorized. Technetium-99m-labeled annexin-V, an endogenous protein that has high affinity for binding to phosphatidylserine, has been administered intravenously for noninvasive identification of apoptotic cell death. In the present study of 18 cardiac allograft recipients, 13 patients had negative and five had positive myocardial uptake of annexin. These latter five demonstrated at least moderate transplant rejection and caspase-3 staining, suggesting apoptosis in their biopsy specimens. This study reveals the clinical feasibility and safety of annexin-V imaging for noninvasive detection of transplant rejection by targeting cell membrane phospholipid alterations that are commonly associated with the process of apoptosis.     

The search for new fragrance ingredients for functional perfumery

Functional perfumery is an integral part of the fragrance business. It demands that the ingredients chosen for compounding withstand the aggressive nature of some of the bases used for soaps, detergents, softeners, bleach, and personal-care products. The synthetic efforts in this area reported in this short personal account, presented in a talk at the RSC/SCI conference Flavours & Fragrances 2004 (Manchester), have resulted in the discovery of the two new proprietary molecules Fleuranil (5/6) and Khusinil (7), which fulfill the criteria of functional perfumery. The structure-odor relationships of several analogs of Fleuranil and Khusinil prepared in the course of these investigations are also presented.     

Amide proton hydrogen exchange rates for sperm whale myoglobin obtained from 15N-1H NMR spectra

The hydrogen exchange behavior of exchangeable protons in proteins can provide important information for understanding the principles of protein structure and function. The positions and exchange rates of the slowly-exchanging amide protons in sperm whale myoglobin have been mapped using 15N-1H NMR spectroscopy. The slowest-exchanging amide protons are those that are hydrogen bonded in the longest helices, including members of the B, E, and H helices. Significant protection factors were observed also in the A, C, and G helices, and for a few residues in the D and F helices. Knowledge of the identity of slowly-exchanging amide protons forms the basis for the extensive quench-flow kinetic folding experiments that have been performed for myoglobin, and gives insights into the tertiary interactions and dynamics in the protein.     

Apoptosis in heart failure: a tale of heightened expectations, unfulfilled promises and broken hearts...

Although apoptosis contributes significantly to remodeling of the fetal heart during evolution of cardiac chambers and correct routing of the great vessels, it has been believed that apoptosis does not occur in terminally differentiated adult cardiac muscle cells. However, apoptosis has recently been demonstrated in animal models of heart failure as well as in explanted hearts from patients with end-stage heart failure undergoing cardiac transplantation. Ventricular dilatation and neurohormonal activation, the hall-marks of heart failure, lead to upregulation of transctription factors, induce muscle cell hypertrophy and prepare cells for entry into the cell-division cycle. However, since terminally differentiated myocytes cannot divide, they die by apoptosis. It has been proposed that low-grade apoptosis in failing heart may be responsible for inexorable decline in left ventricular function. Better understanding of the molecular and cellular basis of apoptosis in the failing myocardium may lead to development of strategies aimed at preventing progressive myocyte loss and deterioration in left ventricular function.     

NMR studies of the conformations of leghemoglobins from soybean and lupin

Phase-sensitive two-dimensional NMR methods have been used to obtain extensive proton resonance assignments for the carbon monoxide complexes of lupin leghemoglobins I and II and soybean leghemoglobin a. The assigned resonances provide information on the solution conformations of the proteins, particularly in the vicinity of the heme. The structure of the CO complex of lupin leghemoglobin II in solution is compared with the X-ray crystal structure of the cyanide complex by comparison of observed and calculated ring current shifts. The structures are generally very similar but significant differences are observed for the ligand contact residues, Phe30, His63 and Val67, and for the proximal His97 ligand. Certain residues are disordered and adopt two interconverting conformations in lupin leghemoglobin II in solution. The proximal heme pocket structure is closely conserved in the lupin leghemoglobins I and II but small differences in conformation in the distal heme pocket are apparent. Larger conformational differences are observed when comparisons are made with the CO complex of soybean leghemoglobin. Altered protein-heme packing is indicated on the proximal side of the heme and some conformational differences are evident in the distal heme pocket. The small conformational differences between the three leghemoglobins probably contribute to the known differences in their O2 and CO association and dissociation kinetics. The heme pocket conformations of the three leghemoglobins are more closely related to each other than to sperm whale myoglobin. The most notable differences between the leghemoglobins and myoglobin are: (a) reduced steric crowding of the ligand binding site in the leghemoglobins, (b) different orientations of the distal histidine, and (c) small but significant differences in proximal histidine coordination geometry. These changes probably contribute to the large differences in ligand binding kinetics between the leghemoglobins and myoglobin.     

Next-generation of melanoma researchers: Trainee perspectives from around the world

The Society for Melanoma Research (SMR) was created 20 years ago and has unequivocally contributed to the vast progress of the field, particularly for the treatment of melanoma patients with metastatic disease by facilitating synergistic collaborations between clinicians, researchers at the bench, and industry. In commemoration of the 20th anniversary of the first SMR International Congress (held in 2003 in Philadelphia), we look to the future by highlighting the perspectives of the next generation of rising stars, medical, and graduate students across six continents.