The detection of a population of submillimeter-bright, strongly lensed galaxies.

Gravitational lensing is a powerful astrophysical and cosmological probe and is particularly valuable at submillimeter wavelengths for the study of the statistical and individual properties of dusty star-forming galaxies. However, the identification of gravitational lenses is often time-intensive, involving the sifting of large volumes of imaging or spectroscopic data to find few candidates. We used early data from the Herschel Astrophysical Terahertz Large Area Survey to demonstrate that wide-area submillimeter surveys can simply and easily detect strong gravitational lensing events, with close to 100% efficiency.

Old galaxies in the young Universe.

More than half of all stars in the local Universe are found in massive spheroidal galaxies, which are characterized by old stellar populations with little or no current star formation. In present models, such galaxies appear rather late in the history of the Universe as the culmination of a hierarchical merging process, in which larger galaxies are assembled through mergers of smaller precursor galaxies. But observations have not yet established how, or even when, the massive spheroidals formed, nor if their seemingly sudden appearance when the Universe was about half its present age (at redshift z approximately 1) results from a real evolutionary effect (such as a peak of mergers) or from the observational difficulty of identifying them at earlier epochs. Here we report the spectroscopic and morphological identification of four old, fully assembled, massive (10(11) solar masses) spheroidal galaxies at l.6 < z < 1.9, the most distant such objects currently known. The existence of such systems when the Universe was only about one-quarter of its present age shows that the build-up of massive early-type galaxies was much faster in the early Universe than has been expected from theoretical simulations.

New mono- and bis-intercalating compounds between DNA base pairs.

With the aim to obtain new bis-intercalating agents in DNA a series of compounds was prepared linking two identical tricyclic moieties (two 4,5'-8-trimethylpsoralen (TMP)) or different (one TMP and one pyrido[3,2-b]quinoline) through a hydrocarburic aminated flexible chai. Bis-psoralen-amines as well as psoralen-pyrydoquinolin-amines were obtained. For comparison the corresponding mono-psoralen-amines were also prepared condensing a TMP moiety with various hydrocarburic aminated chains. Melting profiles of the complexes between bis-psoralen-amines or psoralen-pyridoquinolin-amines and DNA evidence two different thermal transitions, which can be correlated with bis-intercalation which takes place, at least in part, inside duplex DNA. On the other hand mono-psoralen-amines evidenced only one thermal transition, in line with mono-intercalation. Bis-intercalating agents complexed with DNA, under UVA irradiation photoconjugate covalently to the macromolecule, even if to a lower extent in comparison with mono-intercalating agents. Moreover these bis-intercalating agents in the photoreaction with DNA form inter-strand cross-links; also in this case bis-intercalating agents are less active than mono-intercalating agents.

Treatment of Early Stage Hodgkin's Disease According to Risk Factors.

Between January 1981 and December 1987, 95 patients with stage IA (34 patients), IIA (42 patients) and stage IIB (19 patients) Hodgkin's disease (HD) were evaluated in our institution. Thirty patients defined as "high risk" because of either bulky mediastinal disease, systemic symptoms or both were treated with combined modality therapy (CMT). The remaining 65 patients considered as "standard risk" because they presented at diagnosis without any known adverse prognostic factor, received radiotherapy (RT) only. The median follow-up was 39 months. The complete remission (CR) rate was 97% (92/95). The actuarial 3 year overall (OS) and disease free survival (DFS) were 93% and 72% respectively with no differences between the two groups of patients. All 65 "standard risk" patients achieved CR; thirteen (20%) relapsed after a median time of 22 months. Twenty seven of 30 "high risk" patients (90%) achieved CR and six of them (22%) had early relapses. No severe pancytopenia episodes or life-threatening complications occurred during therapy. As far as the risk of second neoplasms is concerned, we observed only a single case of acute non lymphoblastic leukemia 48 months after the completion of CMT. These results indicate that in unfavourable early stage HD, CMT is effective with a probability of more than a 70% DFS 3 years after therapy with an acceptable acute and late toxicity. Patients without "high" risk factors showed the expected response after RT. About 60% of the patients who failed RT could be salvaged by chemotherapy (CT) while refractory cases or patients who relapsed after CMT did poorly with a third line chemotherapeutic regimen. Therefore alternative therapeutic approaches including high dose CT followed by autologous bone marrow transplantation should be considered for this subset of patients.

Present aspects concerning the molecular mechanisms of photochemotherapy with psoralens.

The various photophysical and photochemical events that can be produced by psoralens after their excitation by UV-A radiation are reviewed, with particular reference to their possible significance for induction of photobiological effects. A close correlation has been found between the covalent photoaddition of furocoumarins to the pyrimidine bases of DNA and the inhibition of DNA synthesis inside living cells; this fact underlines the importance of this photoaddition for the antiproliferative effects exerted by furocoumarins. A good correlation has also been found between the formation of cross-linkages in DNA and the induction of erythema on skin; monofunctional furocoumarins, like methyl-angelicin derivatives, are unable to induce erythema, although they have very strong antiproliferative properties.

In vitro photoreactions of selected psoralens and methylangelicins with DNA, RNA, and proteins.

This paper presents an overview of the photophysical and photochemical properties of some furocoumarin derivatives and their interactions and photoreactions with DNA, RNA, and proteins, as well as their ability to produce singlet oxygen. The relevance of these properties in the induction of photobiologic effects is also discussed.

Chemical basis of the photosensitizing activity of angelicins.

Angelicins are a group of compounds that show marked photobiologic activity on various substrates; some of them have been proposed as potential agents for the photochemotherapy of skin diseases. A good correlation exists between the photosensitizing activity of these compounds and their capacity to induce monofunctional lesions to DNA; therefore, we believe the chemical nature of these photolesions, we isolated from the products of hydrolysis of the photocombinations between 5 angelicins (angelicin, 4-methyl, 5-methyl, 5'-methyl, and 5,5'-dimethylangelicin) and DNA, the corresponding new fluorescent monoadducts between the 4',5'-double bond of the furocoumarins and the 5,6-double bond of thymine.

A study of the relationship between photosensitizing and therapeutic activity of 4,5',8-trimethylpsoralen, and its major metabolite 4,8-dimethyl, 5'-carboxypsoralen.

The molecular basis for the clinically observed differences in the skin photosensitizing activity and therapeutic effectiveness of the topically applied and orally administered drug trimethylpsoralen (TMP) was investigated. TMP, when tested topically, is a very potent photosensitizing and therapeutically effective furocoumarin in the treatment of psoriasis. When administered orally, however, it is significantly less photosensitizing and therapeutically a less effective drug than the commonly used furocoumarin 8-methoxypsoralen. This decreased reactivity of oral TMP is attributable to its poor solubility and rapid in vivo metabolic transformation to several inactive (nonphotosensitizing) metabolites, one of which is referred to as 4,8-dimethyl,5'-carboxypsoralen (DMeCP). The supporting evidence has been obtained by: (a) isolation of the urinary metabolite DMeCP and subsequent comparison of its properties with the synthetically prepared DMeCP and its methyl ester; (b) examining the dark and photochemical interactions of TMP, DMeCP, and DMeCP methyl ester with DNA and determining their ability to form interstrand cross-links with DNA; and (c) studying the inhibition of DNA and RNA synthesis in Ehrlich ascites tumor cells and the killing of bacteria and T2 bacteriophages. The structure-activity relationship of TMP and DMeCP also has been examined in normal human subjects and in patients with psoriasis. The order of topical therapeutic effectiveness in terms of ability to clear psoriasis plaques appeared to be: TMP greater than 8-MOP greater than DMeCP methyl ester greater than DMeCP. The data also suggest the methyl ester of DMeCP to be an interesting nonphotosensitizing furocoumarin that photoconjugates to DNA better than 8-MOP and is therapeutically effective in psoriasis.

Photosensitized effects of furocoumarins: the possible role of singlet oxygen.

The capacity of various furocoumarins to generate singlet oxygen in aqueous solution has been determined. The antiproliferative and the skin-photosensitizing activities of the same furocoumarins did not show any correlation with the capacity to generate the singlet oxygen, while these photobiological properties could be correlated with the capacity of furocoumarins to induce photolesions to the DNA.

Sequence specificity in DNA for the interaction with adriamycin or daunomycin.

The interactions of adriamycin and daunomycin with various polydeoxyribonucleotides and some natural DNAs having different base pairs composition were studied by means of fluorimetric titrations. The quenching of the fluorescence occurring in the drugs complexed with polynucleotides and DNA is more efficiently induced by the C-G rich regions than by the A-T rich ones. By contrast, the affinity of the drugs for polynucleotides and DNAs in forming the molecular intercalated complexes is correlated mainly with the sequence of purines and pyrimidines in each strand of the duplex polymers, fairly independently of their nature. The regions having an alternate sequence of purines and pyrimidines in each strand are much more preferred than the regions having a continuous sequence; among the various alternate sequences, those having the structure of poly d(A-T) X poly d(A-T) appear to be a little more preferred than the others.

Photoreactive water-soluble derivatives of psoralen.

Photobinding to DNA and cross-linking formation in vitro, as well as the skin photosensitizing activity on guinea pigs of two water-soluble derivatives of psoralen (5 and 8-diethylaminopropyloxypsoralen hydrochloride) have been studied. For purposes of comparison, the results have been correlated with those obtained, in the same experimental conditions, with 5- and 8-methoxypsoralen. The water-soluble 8-derivative showed an increased photoaddition to DNA and cross-linking formation, when compared with 8-methoxy-derivative; on the contrary, the water-soluble 5-derivative was less photoreactive than the corresponding 5-methoxy-derivative. The skin photosensitizing potency of 8-diethylaminopropyloxypsoralen (the more interesting of the two compounds) appears weaker than that of 8-methoxypsoralen after topical application, but higher after oral ingestion or subcutaneous injection.

New studies on the interaction between 8-methoxypsoralen and DNA in vitro.

Some aspects of the interactions between DNA and 8-methoxypsoralen (8-MOP) in its ground state (complex formation) or in its excited state (photobinding) have been investigated. 8-MOP shows a low affinity towards DNA in the complex formation; this fact minimizes the possible biological consequences deriving from this interaction, when it occurs in vivo. In covalent photobinding to DNA, 8-MOP forms mainly monofunctional adducts, and to a lesser extent bifunctional adducts, showing a behavior similar to that of other linearly condensed furocoumarins (psoralens); the ratio between mono- and bifunctional adducts was found to be 9:1. The covalent photobinding to DNA does not occur at random along the macromolecule, but preferentially at the level of specific receptor sites. The regions having an alternate sequence of A-T seem to be the best receptor sites for the formation of monoadducts while the regions containing an alternate sequence of A-T and C-G appeared to be the preferential sites for the cross-linkage formation.

Drug-protein interaction: plasma protein binding of furocoumarins.

The binding of six furocoumarins (angelicin, psoralen, 8-methoxypsoralen, 5-methoxypsoralen, 8-methylpsoralen, 4,5'8-trimethylpsoralen) to human serum and human serum albumin was studied by equilibrium dialysis using tritium labelled compounds. The results indicated that in serum all furocoumarins are bound mostly by albumin, the extent of binding being related to the structure of the furocoumarins; at any rate, high values of the bound drug, ranging from 84 to 97% were observed. The percentage of binding is strictly related to the water solubility of the compounds. A limited number of binding sites, n = 1-2.4, were detected in the albumin molecule, indicating a high specificity in the binding process. The association constants of the furocoumarins to albumin. Ka, ranged from 1.2 X 10(4) M-1 (8-methoxypsoralen) to 1.9 X 10(5) M-1 (4,5'8-trimethylpsoralen).

Drug-protein interaction: 8-methoxy psoralen as photosensitizer of enzymes and amino acids.

For a better insight of the molecular basis of the photobiological effects of furocoumarins, the relevance of proteins oxydation by singlet oxygen produced by these substrates under irradiation with long u. v. light was studied. Complex oligomeric as well as simple monomeric purified enzymes with high or low molecular weight and different properties and simple amino acids were irradiated under oxygen in presence of 8-methoxy-psoralen. The effects on both proteins and amino acids were compared with those obtained under similar conditions with typical photosensitizers as methylene blue and Rose Bengal. The results indicated that the photooxydation of proteins, although possible, appears to play a minor role, if any, in the mechanism of action of furocoumarin.

Synthesis and photobiological properties of 4,8-dimethyl-5'-carboxypsoralen: a major metabolite of 4,5',8-trimethylpsoralen.

Recently a major metabolite of 4,5',8-trimethylpsoralen (TMeP) (a photochemotherapeutic agent), was isolated from the urine of mice and human volunteers receiving the drug orally; it was identified as 4,8-dimethyl-5'-carboxypsoralen. The synthesis of this compound has been carried out to obtain a distinct confirmation of the structure of the urinary metabolite and to study its photochemical and photobiological properties. The results obtained showed that this interaction and photoreaction with DNA are very poor; this fact can be correlated with the presence of the ionizable carboxylic group that undergoes a repulsion by the phosphate residues of the macromolecule. This hypothesis is confirmed by the higher interaction and photoreaction with DNA of the 4,8-dimethyl-5'-carboxypsoralen methyl ester in which, of course, the ionizable character is no more present. In connection with this very low photoreacting capacity with DNA, the synthesized metabolite proved lacking of photosensitizing effects on human and guinea pig skin. This fact provides an explanation of the very low photosensitizing properties of TMeP when given orally in contrast with the high activity after topical application.