[Conservative surgery in the treatment of rectal tumors. Our experience, 1986-1997]

OBJECTIVE

Our institution's experience with low anterior resection for primary rectal cancer was reviewed to determine cancer treatment results and to identify risk factors for pelvic recurrence.

METHODS

Ninety-two patients treated for primary rectal cancer between 1986 and 1997 were studied retrospectively. All cases was classified according to Astler-Coller. Median follow up was 46 months.

RESULTS

Actuarial 5-year survival for all patients was 79%. Among 28 patients who relapsed, only 9 pelvic recurrence was detected with an actuarial rate of 15% at 5 years. Lymph nodes involvement were associated with increased risk for pelvic recurrence.

DISCUSSION

Low anterior resection permitted by circular stapler provides good treatment for mid-rectal cancers and for some distal rectal cancers. Pelvic recurrence is not correlated with neoplasm localization, T stage and short distal resection margins, but only with the presence of lymph nodes involvement. This result increase the value of the hypothesis that search the pelvic recurrence origin in a extra-parietal disease respect anastomotic disease.

CONCLUSION

Fundamental to prevent pelvic recurrence is the surgical technique that have to remove lymph node en bloc with the rectum doing a dissection along the endopelvic fascia to Denonvillers fascia so to take away completely the mesorectum.

Characterization of the interface between prefabricated gold copings and cast dental alloy in implant restorations

The objective of this study was to analyse the characteristics of the metal interface between the casting of a dental noble alloy and prefabricated gold copings (OCTA-ITI Implant System) after the fabrication procedures of a prosthetic implant-retained superstructure. The microscopical investigation, performed by optical microscopy (OM) and scanning electron microscopy (SEM), of the region around the cylinder after the casting process and the subsequent porcelain firing procedures showed the presence of an ideal interface, including: i) maintenance of coping and casting alloy microstructures up to the interface, and ii) absence of interfacial reaction products. A low content of porosity (less than 3% by volume in average) was observed in the casting alloy bulk as well as at interface. The investigation by energy-dispersive spectroscopy (EDS) of the alloy composition close to the interface showed the presence of a minimal elemental interdiffusion, suggesting that an adequate compatibility between alloy and coping characterized the materials used. A small decrease of the prefabricated coping hardness was also observed after the casting and porcelain firing procedures.

Drugs acting on DNA topoisomerases: recent advances and future perspectives

DNA-topoisomerases, a family of DNA-processing enzymes, represent the pharmacological target of major clinically useful chemotherapeutic agents. These drugs essentially act by trapping a topoisomerase-DNA cleavable complex, an intermediate in the enzyme s catalytic cycle. Research activity in this field continues to grow exponentially, resulting in a wealth of new information on the functional role and the biochemical and structural properties of the enzymes. In addition, the drug pharmacophores have been further characterized, along with their sequence preferences, and key interactions with the target macromolecules are being unveiled. This review will discuss the recent advances in elucidating the mode of action of DNA-topoisomerases and of topoisomerase-targeted anticancer agents.

DNA-binding preferences of bisantrene analogues: relevance to the sequence specificity of drug-mediated topoisomerase II poisoning

To elucidate structure-activity relationships for drugs that are able to poison or inhibit topoisomerase II, we investigated the thermodynamics and stereochemistry of the DNA binding of a number of anthracene derivatives bearing one or two 4, 5-dihydro-1H-imidazol-2-yl-hydrazone side chains (characteristic of bisantrene) at different positions of the planar aromatic system. An aza-bioisostere, which can be considered a bisantrene-amsacrine hybrid, was also tested. The affinity for nucleic acids in different sequence contexts was evaluated by spectroscopic techniques, using various experimental conditions. DNA-melting and DNase I footprinting experiments were also performed. The location and number of the otherwise identical side chains dramatically affected the affinity of the test compounds for the nucleic acid. In addition, the new compounds exhibited different DNA sequence preferences, depending on the locations of the dihydroimidazolyl-hydrazone groups, which indicates a major role for the side-chain position in generating specific contacts with the nucleic acid. Molecular modeling studies of the intercalative binding of the 1- or 9-substituted isomers to DNA fully supported the experimental data, because a substantially more favorable recognition of A-T steps, compared with G-C steps, was found for the 9-substituted derivative, whereas a much closer energy balance was found for the 1-substituted isomer. These results compare well with the alteration of base specificity found for the topoisomerase II-mediated DNA cleavage stimulated by the isomeric drugs. Therefore, DNA-binding specificity appears to represent an important determinant for the recognition of the topoisomerase-DNA cleavable complex by the drug, at least for poisons belonging to the amsacrine-bisantrene family.

Mg(2+)-mediated binding of 6-substituted quinolones to DNA: relevance to biological activity

The interaction of a number of novel 6-substituted quinolone derivatives with DNA in the presence/absence of magnesium ions has been investigated by fluorometric techniques. The drug-single-stranded nucleic acid interaction is invariantly mediated by the metal ion. In all cases optimal complex formation is found at physiological Mg2+ concentration. From titrations at different [Mg2+] the binding constant for the ternary drug-DNA-Mg2+ complex (KT) has been evaluated. Interestingly, a good relationship is found between KT and gyrase poisoning activity of the test quinolones (IC50), which confirms that DNA-affinity of the quinolone, modulated by Mg2+, plays an important role in poisoning the cleavable gyrase-DNA complex and, consequently, in eliciting antibacterial activity in this family of drugs. The results obtained with different 6-substituted compounds supports the idea that position 6 of the drug, besides playing a pharmacokinetic role, is involved in recognition of the enzyme pocket. Our data do not support a mechanism of action based upon quinolone intercalation into B-DNA.

Circulating levels of allopregnanolone in humans: gender, age, and endocrine influences

Allopregnanolone is a neuroactive steroid involved in modulating behavioral functions, stress, and neuroendocrine axes in rats. Changes in plasma allopregnanolone levels throughout the menstrual cycle have been reported in healthy women, but there exists no information on the possible gender or age-related changes or on the source(s) of circulating allopregnanolone. The aim of the present study was to assess serum allopregnanolone concentrations according to gender, menstrual cycle, age, and menopause in normal men and women; serum progesterone (P) and dehydroepiandrosterone (DHEA) levels were evaluated in the same specimens. In addition, the possible source of circulating allopregnanolone in fertile women was investigated by using stimulatory and inhibitory endocrine tests acting on the ovary and/or adrenal cortex. The present study included 189 fertile women, 112 postmenopausal women, and 46 men. Serum steroid levels were determined after extraction, using specific RIAs. Allopregnanolone levels in fertile women in the follicular phase were similar to those in age-matched men; no significant difference was found between fertile women in the follicular phase and postmenopausal women. The highest levels were found in fertile women during the luteal phase (P < 0.01). An age-related decrease was observed in men (P < 0.01), but not in women. P and DHEA levels were significantly higher in women than in men and were higher in fertile women than in postmenopausal women (P < 0.01). Both P and DHEA showed an age-related decrease in men and women (P < 0.01). Serum allopregnanolone and P, but not DHEA, significantly increased in response to a GnRH test, whereas corticotropin-releasing factor and ACTH tests elicited a significant increase in allopregnanolone, P, and DHEA levels (P < 0.01). The suppression of adrenal steroidogenesis by dexamethasone markedly reduced both allopregnanolone and DHEA serum levels (P < 0.01). In conclusion, the present study demonstrated that although men show an age-related decrease, serum allopregnanolone levels in women do not change with age and correlate with P levels during the menstrual cycle and in response to endocrine tests. Ovary and adrenal cortex may be major sources of circulating allopregnanolone in fertile women.

Mapping drug interactions at the covalent topoisomerase II-DNA complex by bisantrene/amsacrine congeners

To identify structural determinants for the sequence-specific recognition of covalent topoisomerase II-DNA complexes by anti-cancer drugs, we investigated a number of bisantrene congeners, including a 10-azabioisoster, bearing one or two 4, 5-dihydro-1H-imidazol-2-yl hydrazone side chains at positions 1, 4, or 9 of the anthracene ring system. The studied bisantrene/amsacrine (m-AMSA) hybrid and bisantrene isomers were able to poison DNA topoisomerase II with an intermediate activity between those of bisantrene and m-AMSA. Moving the side chain from the central to a lateral ring (from C-9 to C-1/C-4) only slightly modified the drug DNA affinity, whereas it dramatically affected local base preferences of poison-stimulated DNA cleavage. In contrast, switching the planar aromatic systems of bisantrene and m-AMSA did not substantially alter the sequence specificity of drug action. A computer-assisted steric and electrostatic alignment analysis of the test compounds was in agreement with the experimental data, since a common pharmacophore was shared by bisantrene, m-AMSA, and 9-substituted analogs, whereas the 1-substituted isomer showed a radically changed pharmacophoric structure. Thus, the relative space occupancy and electron distribution of putative DNA binding (aromatic rings) and enzyme binding (side chains) moieties are fundamental in directing the specific action of topoisomerase II poisons and in determining the poison pharmacophore.

Sensing biological effectors through the response of bridged nucleic acids and polynucleotides fixed in liquid-crystalline dispersions

The formation of three-dimensional structures of double-stranded nucleic acid and polynucleotide molecules, fixed in the structure of liquid-crystalline dispersions and bridged by polymeric chelate complexes is described. The bridging elements consist of alternating daunomycin molecules and copper ions. It is shown that these bridges between nucleic acid molecules stabilize cholesteric structures of the DNA liquid-crystalline dispersion. The formation of polymeric chelate bridges is accompanied by a remarkable increase of the intense circular dichroism (CD) band characteristic of the DNA-daunomycin cholesterics. These bridges are destabilized by a number of biologically relevant compounds and macromolecules, such as ascorbic acid, homocarnosine, bovine serum albumin and lysozyme. The dramatic change in the optical activity of the liquid-crystalline dispersions upon addition of these compounds makes them easily detectable. The sensitivity of the method, in the range of analytic concentration 10(-4)-10(-8) M, depends on the nature of the compound being tested. The response of bridged DNA structures to biological effectors observed here foresees their further development as biosensor devices for detecting the presence of biologically and pharmacologically relevant compounds.

Synthesis, DNA-damaging and cytotoxic properties of novel topoisomerase II-directed bisantrene analogues

New bisantrene analogues were synthesized, bearing one or two 4,5-dihydro-1H-imidazol-2-yl hydrazone side chains at positions 1,4 or 9 of the anthracene ring system. A 10-azabioisostere was also prepared. The position of substituents in structurally isomeric drugs modulates topoisomerase II poisoning and specificity, along with cytotoxicity.

Neuroendocrine effects of different estradiol-progestin regimens in postmenopausal women

OBJECTIVE

New regimens and routes of administration of hormonal replacement therapy (HRT) in climateric women are becoming available. Since there is no information on the neuroendocrine effects of sequential combined treatment with 17 beta-estradiol and a progestin, the present study evaluated the neuroendocrine, clinical vasomotor and psychological changes before and after different sequential combined HRT regimens (17 beta-estradiol plus nomegestrol acetate, or cyproterone acetate, or vaginal progesterone). Vasomotor and behavioral effects were evaluated by using the Kupperman score, while changes in plasma endorphin (beta-END) levels were used as marker of neuroendocrine effects.

METHODS

Postmenopausal women (n = 30) were randomly divided into three groups (ten women for each group); all women received continuous 17 beta-estradiol (50 mg, transdermal) and each group was sequentially treated with different progestins for 12 days/month: group A, cyproterone acetate (5 mg p.o.); group B, nomegestrol acetate (5 mg p.o.); and group C, progesterone (100 mg, vaginal cream). A group of healthy fertile women (n = 8) served as control. Before and after 6 months of HRT, postmenopausal women underwent an evaluation of subjective Kupperman score and two neuroendocrine tests: (a) naloxone (4 mg i.v.) and (b) clonidine (1.25 mg i.v.). Plasma beta-END levels were measured before and at 15, 30, 45, 60 and 90 min after drug injection. Control women were studied by administering the two neuroendocrine tests only once.

RESULTS

Postmenopausal women before HRT showed a pathological Kupperman and no changes of plasma beta-END levels in response to the clonidine and naloxone tests score. On the contrary the increase was significant in healthy women. In each of the three groups of treated women both naloxone and clonidine tests induced a significant increase in plasma beta-END levels (P < 0.01). After 6 months of HRT, an improvement of vasomotor and psychological symptoms was shown by a decrease of Kupperman score.

CONCLUSIONS

The present study indicates that sequential treatment with transdermal 17 beta-estradiol and progestin, no matter which progestin was used, restores the beta-END release, improves vasomotor and psychological symptoms.

Preferred interaction of D-peptidyl-anthraquinones with double-stranded B-DNA

The quest for more specific drugs in antitumor chemotherapy led us to the design of anthraquinone-peptide conjugates capable of selective recognition of the nucleic acid. We present here the DNA binding characteristics, sequence specificity and geometry of interaction of a pair of enantiomers containing the lysine-glycine dipeptide in the side chains. The D enantiomer binds right handed double stranded DNA more efficiently than the L form under all conditions tested. The source of higher binding affinity is not electrostatic in nature and rests in the more favorable hydrophobic contacts of the D-lysyl side chains in the drug-DNA complex. Both derivatives exhibit preference for alternating GC base sequences and intercalate into DNA in a threading mode as suggested by chiroptical and theoretical studies. The D enantiomer, being a peptidyl derivative that contains a non-natural amino acid, has the considerable advantage of being less susceptible to enzymatic hydrolysis and could therefore represent a lead compound for further development.

High dosage alpha-interferon for treatment of children and young adults with chronic hepatitis C disease

BACKGROUND

There are limited data on the use of high interferon (IFN) dosage for treatment of children and young adults with hepatitis C virus infection and in those affected by thalassemia major (TM).

OBJECTIVES

To assess the response of children and young adults with chronic hepatitis C disease, including those affected by TM, to high dose natural alpha-interferon (IFN-alpha). To evaluate the effect of iron overload in response to high dose IFN-alpha in young chronic hepatitis C virus thalassemia patients.

METHODS

We conducted a therapeutic trial of natural IFN-alpha, using 10 million units/m2 three times a week for 6 months in 14 chronic hepatitis C patients ages 5 to 28 years; 7 also had TM. The follow-up period lasted 12 months.

RESULTS

Ten patients (73%) showed normal or nearly normal alanine aminotransferase values at the end of follow-up (biochemical response), but only five (35%) were negative for serum hepatitis C virus-RNA (complete responders). Four of the patients (57%) with TM were sustained complete responders. No correlation was found between the initial serum concentration of ferritin and response to IFN therapy. Patients infected with genotype 1b showed a poor response although high dose of natural IFN was used.

CONCLUSIONS

These results indicate that IFN-alpha can be used in children and young patients with chronic hepatitis C disease as well as in those affected by TM. Treatment with high dosage natural IFN-alpha in children and young adults with hepatitis C infection does not appear to be more effective than dosages previously used.

Growth after recombinant human growth hormone (rhGH) treatment in transplanted thalassemic patients

The aim of this study was to evaluate the treatment effects with recombinant human growth hormone (rhGH) in a group of patients after bone marrow transplantation for thalassemia major. At the end of treatment we divided the subjects into two groups according to the outcome of the therapy: responder and nonresponder. Responder group: after 24 months of rhGH administration, growth rate was still significantly higher in respect to start of treatment (P < 0.0001). Plasma levels of IGF-I rose significantly (P < 0.003). The serum levels of serum asparate aminotransferase (SGOT) and alanine aminotransferase (SGPT) were higher compared to normal values but improved in non-responder patients. There was no difference in the mean concentration of these parameters before and after treatment (P = NS). Non-responder group: these patients had a worsening of the growth rate during rhGH administration. There was no increase of the IGF-I levels. Single values of transaminase and ferritin levels were higher than in responder patients before and after treatment. There was a significant correlation between IGF-I, SGOT, SGPT and ferritin in all patients before and after therapy. It appears from these data that rhGH administration is worth serious consideration in patients after BMT for thalassemia major presenting impaired growth hormone secretion. This treatment can offer good results only in cases where the normal hepatic synthesis of IGF-I is conserved and where liver damage has not reached irreversible conditions, as we have seen in the responder group.

A protein-mediated mechanism for the DNA sequence-specific action of topoisomerase II poisons

Chemical agents able to interfere with DNA topoisomerases are widespread in nature, and some of them have outstanding therapeutic efficacy in human cancer and infectious diseases. DNA topoisomerases are essential enzymes that govern DNA topology during fundamental nuclear metabolic processes. Topoisomerase-interfering compounds can be divided into two general categories based on the mechanism of drug action: poisons and catalytic inhibitors. In past years, investigations of the DNA sequence selectivity of topoisomerase II poisons have identified structural and molecular determinants of drug activity, and indicated that the drug receptor is likely to be at the protein-DNA interface. Moreover, the available results indicate that the biologically relevant DNA-binding activity of topoisomerase poisons is basically protein-mediated and this is discussed in this issue by Giovanni Capranico and colleagues. This suggests that topoisomerase poisons may represent a useful paradigm for small compounds able to bind to protein-DNA interfaces in a site-selective manner, thus increasing the affinity of DNA-binding proteins for specific genomic sites.

Liquid-crystalline structure of nucleic acids: effect of antracycline drugs and copper ions

The formation of liquid-crystalline dispersions (L.C.D.) from double-stranded DNA and polynucleotide (NA) molecules complexed with a number of anthracycline derivatives was investigated. These drugs form two types of complexes (complex I and complex II) with NA, which differ in the mode of drug orientation in respect to the NA helical axis. When complex II forms, addition of copper ions causes bridging of neighboring NA molecules through polymeric copper-anthracycline links (Figure 1). This results in an extra-increase in the amplitude of the intense CD band, characteristic for complex II, in the drug absorption region. Comparison of data obtained for different analogs and derivatives of daunomycin, has shown that the presence of 4 coordinating oxygen atoms at positions 5,6 and 11,12 (or 1,12) of the anthracycline ring system represents the basic prerequisite for the formation of a long polymeric chelate bridge after addition of copper ions. A second requirement relates to the chemical and stereochemical properties of sugar residues at position 7. These are important for proper positioning of the neighboring anthracycline aglycones in the polymeric chelate bridges and for spatial fixation of Cu2+ ions. Base sequence of double-stranded polynucleotides plays, if any, a minor role in polymeric chelate bridge formation. The question concerning the sterical orientation of two neighbouring antracyclines in the linking bridges, formed between NA molecules fixed in the liquid-crystalline structure, remains open.

Irreversible and reversible topoisomerase II DNA cleavage stimulated by clerocidin: sequence specificity and structural drug determinants

In contrast to other topoisomerase II poisons, the microbial terpenoid clerocidin was shown to stimulate irreversible topoisomerase II-mediated DNA cleavage. To establish the structural determinants for drug activity, in this study we have investigated intensity patterns and sequence specificity of clerocidin-stimulated DNA cleavage using 5'-end 32P-labeled DNA fragments. At a majority of the sites, clerocidin-stimulated cleavage did not revert upon NaCl addition; nevertheless, at some sites, cleavage completely reverted. Statistical analyses showed that drug-preferred bases were different in the two cases: guanine and cytosine were highly preferred at position -1 at irreversible and reversible sites, respectively. These results demonstrated that cleavage irreversibility was site selective and required a guanine at the 3' end of the cut. Further experiments revealed that some irreversible sites showed an abnormal electrophoretic mobility in sequencing gels with respect to cleaved bands generated by 4-(9-acridinylamino)methanesulfon-m-anisidide, suggesting a chemical alteration of the DNA strand. Interestingly, the ability to stimulate irreversible cleavage progressively decreased over time when clerocidin was stored in ethanol. Under these conditions, nuclear magnetic resonance measurements demonstrated that the drug underwent structural modifications that involved the C-12-C-15 side chain. Thus, the results indicate that a specific moiety of clerocidin may react with the DNA (guanine at -1) in the ternary complex, resulting in cleavage irreversibility and in altered DNA mobility in sequencing gels.

Amido analogs of mitoxantrone: physico-chemical properties, molecular modeling, cellular effects and antineoplastic potential

To assess the effects of amido substitution in the side-chains of the anticancer drug mitoxantrone (MX) two analogs were synthesized, having hydroxyethylaminoacetyl- and hydroxyethylaminopropionyl- substituents at the nitrogens located at positions 1, 4 of the anthracenedione ring system. The novel derivatives exhibit DNA-affinity and redox properties similar to the parent drug. However, unlike MX, they are not able to stimulate DNA cleavage, as shown by alkaline elution experiments. Molecular modeling studies using ab initio quantum mechanical methods show that, while the stereochemistry of the drug molecule is not appreciably affected when an amide group replaces the aromatic amino function, the reverse is true for the electrostatic properties. Indeed, overlapping of electron density of MX with its analogs is very poor. Moreover, a reversal in the direction of MX dipole moment occurs in the amido congeners. This may explain the lack of recognition of the cleavable topoisomerase II-DNA complex and loss of cleavage stimulation. However, the new derivatives exhibit pharmacological activity comparable to that found for MX, as they are remarkably cytotoxic and are active in vivo against P388 murine leukemia. Hence, amido substitution may lead to a different mechanism of cytotoxicity, not related to classical protein or free radical-mediated DNA damage, which points to a novel type of antineoplastic pharmacophore.

Physicochemical properties, cytotoxic activity and topoisomerase II inhibition of 2,3-diaza-anthracenediones

The physicochemical, cytotoxic and pharmacological properties of 2,3-diaza-anthracenedione derivatives were examined to gain insight into the structure-activity relationships in this class of compounds. Spectrophotometric, chiroptical and voltammetric measurements were performed, along with cell cytotoxicity, alkaline elution, topoisomerase II-mediated DNA cleavage and cellular drug-uptake determination. In comparison with classic anthracenediones such as mitoxantrone and ametantrone, the aza derivatives were characterized by less negative reduction potentials, lower affinity for DNA and modified geometry of intercalation. The biological effects of the new compounds were also profoundly affected by bioisosteric N for C replacement. Stimulation of topoisomerase II-mediated DNA cleavage was not observed, whereas other mechanisms of cell cytotoxicity, possibly involving oxidative DNA damage appeared to be operative. The inability to generate protein-associated strand breaks could be explained by an unfavorable orientation of the drug in the intercalation complex rather than by a reduced binding to DNA. Geometry of drug intercalation may have a critical influence on the formation of the ternary complex. In turn, the onset of a different DNA-damaging pathway is likely to be related to easy redox cycling of the 2,3-diaza-substituted anthracenedione derivatives, which could produce radical species to a remarkably greater extent than could the carbocyclic parent drugs.

Potent 6-desfluoro-8-methylquinolones as new lead compounds in antibacterial chemotherapy

In a furtherance of our SAR study on the C-6 position of quinolone antibacterials, a series of 6-desfluoro-8-methylquinolones were synthesized and evaluated for their in vitro antimicrobial activity. As a result of this study, compounds with strong activity against Gram-positive bacteria, including ciprofloxacin-resistant and methicillin-resistant Staphylococcus aureus, were identified. The best Gram-positive antibacterial activity was exhibited by piperidinyl derivative 6c, which was 17 times more potent than ciprofloxacin and displayed extremely high activity against Streptococcus pneumoniae with an MIC value of <0.016 microg/mL. Thus, we have shown that substituent combinations in the quinolone ring, excluding the C-6 fluorine atom, might produce powerful antibacterial agents.

Adjustable 'cross-linking' of neighboring DNA molecules in liquid-crystalline dispersions through (daunomycin-copper) polymeric chelate complexes

The interaction of daunomycin molecules with double-stranded DNA in the liquid-crystalline state was investigated. It was shown that at a certain extent of daunomycin binding a change of the mechanism of anthracycline orientation with reference to the DNA chain occurs. This is testified by the alteration of the sense of spatial packing of the DNA molecules in liquid-crystalline dispersions formed as a result of phase separation in poly(ethyleneglycol)-containing solutions, as well as by the onset of the reaction of daunomycin with divalent copper ions. Using this reaction, polymeric (daunomycin-copper) chelate cross-links between the DNA molecules fixed in the liquid-crystalline dispersions were formed. The length of such cross-links as adjusted by the distance between the DNA molecules, which, in turn, depends on the concentration of poly(ethyleneglycol) used for phase separation. The above molecular building mechanism may lead to new interesting applications.

Aza-bioisosteres of 9, 10-anthracenedione: a modulation of DNA sequence specificity

The sequence specificity of DNA-binding by monoaza- and diaza-anthracenedione analogues of mitoxantrone (MX) has been investigated by DNase 1 footprinting and spectroscopic techniques. More than 100 sites cut by the enzyme were sequenced on three pBR 322 and simian virus 40 DNA restriction fragments. Different inhibition and stimulation effects were observed as a function of the structural properties of each drug. A gradual change was found from MX to monoaza derivatives and from these to diaza derivatives, corresponding to a broader distribution of drug-inhibited regions. In addition to almost all sites found with MX (38 of 44), 29 new inhibition sites were observed using the diaza compound BBR 2894. The sequence analyses in terms of base doublets or triplets confirm the preference of MX for alternating pyrimidine-purine sites, the most significant triplet sequences being (5' to 3') CTA, GCA, TAC, ACT, CAC and TTA. In addition to MX sites, BBR 2894 seemed to bind efficiently to pyrimidine-pyrimidine-pyrimidine or purine-pyrimidine-pyrimidine triplets containing CT or TC motifs. Differential cleavage plots essentially confirmed the above results. Spectrophotometric and chiroptical studies showed a decreased DNA-binding affinity and a modified geometry of intercalation when nitrogen replaces carbon in the anthraquinone ring. These results can be useful for understanding the substantially different biological responses exhibited by aza-substituted anthracenedlones when compared with their non-substituted, pharmacologically relevant congeners.

Quality of life in shift work syndrome

Air Force radar controllers represent an excellent example of night shift workers, as they are obliged to demonstrate perfect alertness during working hours. We set out: a) to assess the quality of life in these shift workers; b) to identify those with shift work syndrome and c) to evaluate the possible effects of triazolam both on their quality of life and sleep. The results reveal an impairment of the quality of life in shift workers, independently of the presence of a circadian rhythm sleep disorder. Quality of life was more severely impaired in subjects with circadian rhythm sleep disorder. Hypnotic therapy brought about an improvement both in the sleep disorder and in the quality of life of subjects affected by shift work syndrome. Selective alertness tests failed to demonstrate any "sedative carry-over" in the treated patients.

Peptidyl anthraquinones as potential antineoplastic drugs: synthesis, DNA binding, redox cycling, and biological activity

A series of new compounds containing a 9,10-anthracenedione moiety and one or two peptide chains at position 1 and/or 4 have been synthesized. The amino acid residues introduced are glycine (Gly), lysine (Lys), and tryptophan (Trp), the latter two in both the L- and D-configurations. The peptidyl anthraquinones maintain the ability of intercalating efficiently into DNA, even though the orientation within the base-pair pocket may change somewhat with reference to the parent drugs mitoxantrone (MX) and ametantrone (AM). The interaction constants of the mono-, di-, and triglycyl derivatives are well comparable to those found for AM but 5-10 times lower than the value reported for MX. On the other hand, the glycyl-lysyl compounds bind DNA to the same extent as (L-isomer) or even better than (D-isomer) MX. As for the parent drugs without peptidyl chains, the new compounds prefer alternating CG binding sites, although to different extents. The bis-Gly-Lys derivatives are the least sensitive to base composition, which may be due to extensive aspecific charged interactions with the polynucleotide backbone. As far as redox properties are concerned, all peptidyl anthraquinones show a reduction potential very close to that of AM and 60-80 mV less negative than that of MX; hence, they can produce free-radical-damaging species to an extent similar to the parent drugs. The biological activity has been tested in human tumor and murine leukemia cell lines. Most of the test anthraquinones exhibit cytotoxic properties close to those of AM and considerably lower than those of MX. Stimulation of topoisomerase-mediated DNA cleavage is moderately present in representatives of the glycylanthraquinone family, whereas inhibition of the background cleavage occurs when Lys is present in the peptide chain. For most of the test anthraquinones, the toxicity data are in line with the DNA affinity scale and the topoisomerase II stimulation activity. However, in the lysyl derivatives, for which lack of cytotoxicity cannot be related to poor binding to DNA, the steric and electronic properties of the side-chain substituent must impair an effective recognition of the cleavable complex.

Growth charts, growth velocity and bone development in childhood obesity

OBJECTIVE

To compare the growth charts of obese subjects (4-18 years) with the Tanner's growth curves and to analyze the growth velocities and bone age of obese children in prepuberty and adolescence. Moreover to compare the relationship between the serum insulinemic and glycemic levels and height standard deviation score (HSDS).

DESIGN

Growth charts: this study included 1250 obese subjects (669 males, 581 females) observed between 1981 and 1993 and divided into seven age categories (4-6, 7-8, 9-10, 11-12, 13-14, 15-16, 17-18 years). Growth velocities: yearly growth velocities of 579 obese subjects (325 males, 254 females) were compared to growth velocities of 473 controlled children of the same sex, chronological age and pubertal stage. Bone age (BA) of 846 obese subjects (470 males, 376 females) was estimated. Blood analysis: insulin secretion of 70 obese children was considered and compared to 70 lean controls of equal chronological age and sex.

MEASUREMENTS

Growth rate, standardized height and other physical characteristics of the children were measured by trained examiners. All subjects were evaluated singularly for at least 4 years with a follow-up every 6 months. BA was estimated by radiograph of the left hand and wrist using the Tanner-Whitehouse II system by a single observer. For the insulin secretion study and glycemic levels oral glucose tolerance test (OGTT) was performed using a glucose load of 1.75 g/kg per body weight. Plasma insulin was assessed by a double antibody radioimmunoassay.

RESULTS

In adipose children the growth charts, referred to 97th centile, 50th centile and 3rd centile, were superior to those of the normal population up to the age of 13 and 12.5 years for male and for female respectively; growth decreases at the above age in both sexes. The obese subjects were equal in height to the non obese subjects as they reached their 18th birthday. The growth velocity (cm/yr) of the obese child, in the age range considered here, does not show differences when compared with the lean child in the prepubertal status (P not significant) but decreases during Tanner's stage II, III IV in boys and girls (P < 0.0001). BA is more advanced over chronological age (delta BA-CA) in both sexes. The increase of BA over CA does not show a remarkable difference during pubertal maturation in boys (P not significant); whereas in girls the delta BA-CA decreases with advancing sexual maturation (P < 0.0001). Our obese subjects have significantly higher plasma insulinemic levels compared with the lean controls (P < 0.0001). Moreover there is a positive correlation between plasma insulinemic levels and HSDS (r = 0.881, P < 0.0001). We did not observe a correlation between serum glycemic levels and HSDS.

CONCLUSION

Our data demonstrate that the growth increase in an obese child starts in the first years of life. The statural advantage acquired in the first years of life would be exploited and maintained up to the beginning of puberty and with a growth velocity equal to that of the lean subject. Skeletal maturation is strongly increased in both sexes. Bone age remained advanced during the entire period of pubertal development. During puberty obese subjects demonstrate a less notable growth spurt when compared with lean subjects. The growth advantage gradually decreases and final adult height of obese and normal subjects is equal.

Topoisomerase II DNA cleavage stimulation, DNA binding activity, cytotoxicity, and physico-chemical properties of 2-aza- and 2-aza-oxide-anthracenedione derivatives

The cytotoxic activity of mitoxantrone and related anthracenediones has been ascribed to the ability of these compounds to interfere with DNA topoisomerase II function, resulting in DNA cleavage stimulation. The molecular details of enzyme inhibition by these intercalating agents remain to be defined. In an attempt to identify the structural determinants for optimal activity, the molecular and cellular effects of a series of heteroanalogues bearing different side-chains were examined in relation to the physico-chemical and DNA binding properties of these compounds. The results indicated that substitution of a pyridine ring for the dihydroxyphenylene ring in the planar chromophore caused a marked reduction of cytotoxic activity and of the ability to stimulate topoisomerase II-mediated DNA damage in intact cells and with simian virus 40 DNA in vitro. Although all tested derivatives were shown to intercalate into DNA, their DNA binding affinities were appreciably lower than that of mitoxantrone. The behavior of 2-aza derivatives more closely resembled that of ametantrone, suggesting that the potency of agents of this class is influenced more by the presence of hydroxyl groups than by the phenylene ring. The observation that a dramatic reduction (or loss) of the ability of aza derivatives to stimulate DNA cleavage is associated with a marked reduction of cytotoxic potency supports a primary role of topoisomerase II-mediated effects in the mechanism of action of the effective agents of this class. Because appreciable cytotoxic activity and significant in vivo antitumor efficacy are retained by compounds inactive (or poorly active) in inhibition of topoisomerase II, these results are consistent with multiple effects of anthracenediones at the cellular level.

Effects of tacrine upon murine neuroblastoma cells

Tacrine [9-amino-1,2,3,4-tetrahydroacridine] (THA), a potent acetylcholinesterasic inhibitor, is utilized in the pharmacological treatment of Alzheimer's disease (Birne and Arie, 1994). Cytopharmacology of THA is still largely to be discovered. In the present paper we report some effects produced by THA on murine neuroblastoma cells (N2A) used as an experimental model. N2A cells treated with THA at low concentration (1 mu M) showed a reduced cell's mitosis and a remarkable reduction of protein synthesis. Eventually, a marked reduction on the phosphorylation of proteins associated to neurofilaments 200 kD, is observed using specific antibody.

Chromophore-modified antitumor anthracenediones: synthesis, DNA binding, and cytotoxic activity of 1,4-bis[(aminoalkyl)amino]benzo[g]-phthalazine-5,10-diones

As part of a program aimed at exploring the effect of the introduction of heteroatoms into the anthracene-9,10-dione chromophore, we have synthesized novel 1,4-bis[(aminoalkyl)amino]-benzo[g]phthalazine-5,10-diones (BPDs) 1 which are related to the antitumor agents ametantrone and mitoxantrone. Derivatives 1 were prepared by chromic acid oxidation of acylated benzo[g]phthalazines 5 followed by acid hydrolysis or by silylation-amination of 5,10-dihydroxybenzo[g]phthalazine-1,4-dione (8). The 1-[(aminoalkyl)amino]-4-amino congeners 2 were isolated in low yields as byproducts from the oxidation of 5. Against a panel of human tumor cell lines, the benzo[g]phthalazine-5,10-diones 1 and 2 exhibited cytotoxic activity comparable or even superior to that of mitoxantrone. In compounds 1, structure-activity relationships different than those operative in the carbocyclic series appeared to emerge. DNA-binding studies with the ametantrone-like compound 1c and its single-armed congener 2c indicated that the introduction of a 2,3-diaza subunit into the anthracene-9,10-dione chromophore reduces the affinity of the drug for DNA in comparison with ametantrone. On the other hand, the number of side-chain groups does not affect binding to a great extent. These findings seem to suggest mechanisms of cell death other than those induced by simple interaction of the 1,4-BPDs 1 and 2 with DNA.

Growth and endocrine function following bone marrow transplantation for thalassemia

Twenty two patients with thalassemia major who received successful bone marrow transplantation (BMT) were followed to verify the impact of the transplant procedure on subsequent growth and development. The transplant preparative regimen consisted of busulphan and cyclophosphamide. Growth and endocrinological function were assessed during the first 4 years following BMT. At the time of transplant most patients showed growth retardation. The median difference between chronological age and bone age was -9.5 months for the boys and -8.5 months for the girls. Patients > 7 years old at the time of BMT showed a significant worsening of their growth delay at 48 months following BMT compared with 12 months before transplantation. Patients < 7 years at the time of BMT had their growth retardation constant over time span after transplantation. Moreover six of 11 younger patients showed an improvement of their growth delay compared with one of 11 older patients. The outcome of height standard deviation score at 24 and 48 months following BMT was strictly correlated with the level of serum transaminases and ferritin. Sixteen patients had impaired growth hormone secretion after a provocative test evaluated at 24 months after transplant. At 48 months there was no significant increase in the mean peak GH levels. This study confirms that the growth retardation of patients with thalassemia major is multifactorial.

Continuous mitoxantrone infusion in pretreated epithelial ovarian cancer

Mitoxantrone has shown moderate activity in advanced epithelial ovarian cancer following intermittent i.v. administration. Experiments and clinical data suggest that long-term continuous drug infusion may achieve a better therapeutic result with less toxicity. This hypothesis was tested in patients with advanced ovarian cancer who had been pretreated with other agents. Mitoxantrone was infused continuously in 21-day courses beginning every 6 weeks. If severe toxicity did not occur, the infusion rate was increased by 0.1-0.2 mg/m2 per day. The mitoxantrone solution proved to be stable over the 21-day infusion period. For ethical reasons an optimal two-stage design was employed. The trial was interrupted at the end of the first recruitment stage because the target of 3 responses out of 13 patients had not been achieved (only 1 patient had a partial response). Hematologic toxicity was observed in 11 patients, and 2 of them had a catheter occlusion. In conclusion, we found that 21-day of infusion of mitoxantrone apparently has no clinical benefit as compared with bolus administration in patients with advanced ovarian cancer.

Acute stress- or lipopolysaccharide-induced corticosterone secretion in female rats is independent of the oestrous cycle

The aim of the present study was to test whether oestrous cycle is associated with the hypothalamus-pituitary-adrenal (HPA) axis function. Thus, corticosterone secretion in rats was investigated following lipopolysaccharide (LPS), acute cold-swimming or ether stress or synthetic corticotrophin-releasing factor (CRF) administration throughout the oestrous cycle. Moreover, plasma corticosterone response to cold-swimming stress or LPS administration also was studied at different times of day on pro-oestrus of di-oestrus-I. The following observations were obtained: the morning plasma corticosterone levels in control rats did not differ with the stage of the oestrous cycle; plasma corticosterone levels increased significantly following LPS administration (2 mg/kg, ip) or following acute exposure to cold (4 degrees C)-swimming or ether stress. However, this increase in plasma corticosterone levels was not related to the stage of the oestrous cycle; synthetic CRF injection induced an increase in plasma corticosterone levels constant on di-oestrus-I and pro-oestrus; plasma corticosterone response to LPS administration or acute cold-swimming stress showed diurnal changes, with the lowest values at 18.00 h, which was independent of the oestrous cycle. By showing the unchanged corticosterone response to LPS, to acute stress and to exogenous CRF throughout the oestrous cycle, and the independence of the diurnal pattern of stress response on the oestrous cycle, the present study suggests that the oestrous cycle has no influence on the HPA activity under the present experimental conditions in rats.

Unique sequence specificity of topoisomerase II DNA cleavage stimulation and DNA binding mode of streptonigrin

Streptonigrin stimulated unique intensity patterns of topoisomerase II-mediated DNA cleavage in agarose and sequencing gels with no similarity to those of doxorubicin, VM-26,4'(9-acridinylamino)-methanesulfon-m-anisidide, genistein, and mitoxantrone. Surprisingly, a statistical analysis of 60 sites stimulated by streptonigrin in SV40 and pBR322 DNAs showed that the drug required the dinucleotide 5'-TA-3' from 2- to 3-positions at the DNA cleavage site. Streptonigrin did not intercalate into the double helix; however, a positive value of the reduced linear dichroism indicated that indeed the drug interacted with the DNA. An angle of 45 degrees was found between the major drug and local DNA axes, suggesting a minor groove binding mode. Moreover, a DNA winding assay showed that streptonigrin may tighten the helical twist of DNA, similar to the known minor groove binder distamycin. Drug competition for receptor site binding was then evaluated by drug combination in the cleavage reaction. DNA cleavage intensity patterns were altered only with the streptonigrin/mitoxantrone combination, suggesting that the two compounds may compete for ternary complex formation. The results indicate that streptonigrin may bind to the DNA in a manner similar to that of minor groove binders and that its pharmacophore, possibly different from other topoisomerase II inhibitors, may be an important determinant of its unique sequence position specificity.

Assessment of the relevance of zona pellucida antibodies in follicular fluid of in-vitro fertilization (IVF) patients

The presence of anti-zona pellucida antibodies in the follicular fluid of 11 women who underwent in-vitro fertilization (IVF) and embryo transfer was analysed. Only infertile couples with tubal or unexplained pathologies were included in our study, which was aimed at investigating the relationship between anti-zona pellucida antibodies in follicular fluid and failed fertilization. Whether or not these antibodies were present in some or all follicles in the same patient was also investigated. Out of 55 follicular fluids analysed, 36.3% were positive to the test and no fertilization was observed in oocytes from these follicles, while 63.6% were negative, and the oocyte fertilization rate associated with these was 51.4%. The presence of anti-zona pellucida antibodies was positively correlated with the degree of fertilization failure (P < 0.001 chi 2 test).

Conformational properties of topoisomerase II inhibitors and sequence specificity of DNA cleavage

The sequence specificity of topoisomerase-II-mediated DNA cleavage, stimulated by 2-methyl-9-hydroxy ellipticinium and 4',5,7-trihydroxyflavone (genistein) was investigated by sequencing analysis of DNA cleavage sites and molecular modeling techniques. The former drug exhibits a marked preference for a T base at the position immediately preceding the cleavage site (-1). The latter shares the preference for the same base, with an additional preference for a thymine at position +1. The cleavage intensity patterns in the presence of the two drugs differ considerably. From a conformational point of view, ellipticinium and genistein exhibit similar overall shape and dimensions. However, the fused ring system in the former generates a planar structure whereas the single bond, connecting the two aromatic portions in the latter, allows internal rotation. The most stable conformation of genistein corresponds to a deviation of about 40 degrees from planarity. A computer-assisted analysis was carried out to compare the steric and electrostatic properties of the two compounds. Two types of preferred (energetically almost degenerate) alignment for the two molecules were found. One corresponds to overlapping of the 9-hydroxyl containing ring of ellipticinium with the 4'-hydroxyphenyl moiety of genistein, the other envisages the same moiety of ellipticine superimposed to the hydroxyl-benzopyrone portion of genistein. The structural similarities of the test drugs might account for the common preference for stimulation of DNA cleavage at position +1, whereas the different possible arrangements of genistein in the cleavable complex could explain both the additional +1 specificity exhibited by this compound and the differences in cleavage intensity patterns observed in comparison to ellipticinium.

Conformational drug determinants of the sequence specificity of drug-stimulated topoisomerase II DNA cleavage

To gain further knowledge of the molecular features of topoisomerase II inhibitors required for drug-receptor complex formation, we investigated the conformational drug determinants of the sequence specificities of drug-stimulated DNA cleavage by computer-aided molecular modeling techniques. DNA sequence specificities of bisantrene, genistein, piroxantrone and ellipticinium were determined by using simian virus 40 DNA and compared to those of mitoxantrone, 4-demethoxydaunorubicin, VM-26 and mAMSA. DNA cleavage intensity patterns of bisantrene and mAMSA were virtually identical in sequencing gels, although these drugs are of distinct chemical classes. Genistein and ellipticinium showed drug-specific DNA cleavage intensity patterns with no apparent similarity to other drugs or to each other. From 54 to 72 drug-stimulated sites were sequenced, and local base sequence specificities were established by statistical analyses. In complete agreement with mAMSA requirements, bisantrene required an adenine at position +1. Ellipticinium required a thymine and excluded a cytosine at position -1. Genistein was the only drug showing base requirements (thymines) at both positions -1 and +1. Piroxantrone (structurally related to mitoxantrone) required a pyrimidine at position -1. Since the common sequence specificity of bisantrene and mAMSA could not be simply explained by the nature of some chemical substituents, a comparative molecular modeling analysis of the drugs was carried out based on their steric and electronic attributes. Energy-minimized structures of mAMSA and bisantrene were very similar, since their planar aromatic domains and pendant side-chains overlapped to a very good approximation. In contrast, their most stable conformations were different from other drug structures. In particular, the planar system and pendant sugar moiety of doxorubicin, which also required an adenine but at position -1, was not superimposed to the corresponding moieties of mAMSA and bisantrene even when considering computer-generated conformations with higher energy contents. The most stable conformations of the other drugs studied revealed specific three-dimensional motifs. Therefore, since in a simple model of drug action each spatial region has a single chemical-pharmacological function, these results suggest that bisantrene and mAMSA share common steric and electronic features that may constitute a specific pharmacophore. We suggest that the molecular properties of this pharmacophore may be critical determinant of the +1 position specificity shown by mAMSA and bisantrene.

Synthesis and photobiological properties of 4-hydroxymethyl-4'-methylpsoralen derivatives

The synthesis and the photobiological activity of two new hydroxymethyl derivatives of psoralen namely 4-hydroxymethyl-4'-methyl- and 4-hydroxymethyl-4'-methyl-8-methoxypsoralen are described. Both compounds exhibited efficient photobinding to DNA and RNA. The DNA-photobinding process was investigated using different nucleic acid structures such as double-helical DNA, ribosomal RNA, bacterial DNA and DNA organized in the nucleosomal arrangement. The test derivatives were able to induce cross-links to a similar extent as 8-methoxypsoralen (8-MOP), used as a reference photochemotherapeutic drug. In contrast to 8-MOP, they produced relatively high levels of 1O2. Most photobiological effects (DNA synthesis inhibition, T2 phage sensitization, inhibition of tumor transmitting capacity) showed a good correlation with the extent of covalent photoaddition. On the other hand, the new 4-hydroxymethylpsoralens were unable to induce skin erythema, in striking contrast with 8-MOP. Thus, neither cross-linking of the nucleic acid nor 1O2 production were coupled with skin phototoxicity in this class of compounds. The new derivatives appear to represent an important beginning to development of new active photochemotherapeutic agents devoid of undesired phototoxic side effects.

On the mechanism of action of quinolone drugs

Antibacterial quinolones are thought to inhibit DNA gyrase by trapping the enzyme as a complex with the DNA substrate. The precise molecular details of drug-DNA and drug-enzyme interactions remain controversial. Here, a model is proposed that accounts for the influence of magnesium ions on quinolone-DNA binding.

[Formation of various types of complexes upon the interaction of anthraquinones with DNA]

The optical properties (circular and linear dichroism) of the 11 anthraquinone antibiotics complexed with DNA molecules under conditions giving rise to cholesteric liquid-crystalline dispersions were investigated. Complexes of compounds A911 and A912 with double-stranded linear or circular DNA molecules differ strongly in their properties from those of other anthraquinones. The possible reasons of these differences and their possible correlation with the biological activity of the A911 and A912 are discussed.

Sequence selectivity of topoisomerase II DNA cleavage stimulated by mitoxantrone derivatives: relationships to drug DNA binding and cellular effects

Mitoxantrone, a DNA intercalator, is an effective antitumor drug known to interfere with topoisomerase II function through stimulation of enzyme-mediated DNA cleavage. To clarify the drug structural requirements for stimulation of topoisomerase II DNA cleavage, the cytotoxic activity and molecular effects of mitoxantrone, ametantrone, and a new derivative (BBR2577), bearing a modification on one of the side chains, were examined in relation to their DNA binding affinities and modes of drug-DNA interaction. The results showed a good correlation between cytotoxicity and topoisomerase II DNA cleavage. The modification of one side chain did not influence the cytotoxic potency or the ability of the drug to stimulate DNA cleavage. In contrast, removal of the hydroxyl substituents in the planar aromatic moiety (ametantrone) markedly affected the efficacy of the drug. Ametantrone showed a markedly lower capacity, compared with the other two compounds, to induce cleavable complexes both in intact cells and in SV40 DNA, which suggests a critical role of these substituents in the formation of the ternary topoisomerase II-DNA-drug complex. The poor efficacy of ametantrone is likely due to low stability of the ternary complex. This is possibly related to a different orientation of the drug chromophore intercalated into DNA, compared with those of mitoxantrone and BBR2577. The DNA cleavage efficiencies of the tested drugs at low concentrations correlated with the DNA binding affinity. Identical DNA cleavage patterns were observed with the three compounds, which suggests that all tested drugs share a similar specificity for interaction with sites recognized by the enzyme.

Relevance of DNA binding to the mechanism of anti-herpesvirus activity of benzhydrazone

Benzhydrazone (1H-benz(f)indene-1,3(2H)-dione bis (amidino-hydrazone) (BH) is a synthetic compound with selective anti-herpesvirus activity. Its selectivity seems to stem from the inhibition of viral protein glycosylation and several hypotheses have been formulated to explain such an effect. Data presented here demonstrate that DNA binding is a prominent feature of BH. Interaction is taking place with a relatively high affinity constant and is more efficient for GC-rich viral sequences. Experiments with the cloned DNA fragments from a BH-resistant virus strain indicate that BH-DNA complex formation is drastically reduced as compared to BH-sensitive virus. The occurrence of the resistant phenotype in HEp-2 cells but not in Vero cells could be explained by differences in BH cytotoxicity. Changes in drug uptake and accumulation by cells following infection, in addition to GC preference, may also account for the degree of antiviral selectivity shown by BH.

Benzo- and tetrahydrobenzo-psoralen congeners: DNA binding and photobiological properties

Four new benzo- and tetrahydrobenzo-psoralens have been examined in their reversible interaction toward DNA and in their DNA-photobinding properties. These compounds were also examined for their ability to produce singlet oxygen and in vivo skin photosensitization reaction. Fluorescence and equilibrium dialysis measurements show that the complexation ability of benzoderivatives is remarkably high. Binding is less effective in the case of the tetrahydrocongeners. All compounds photoreact quite effectively to DNA. The photoadducts were obtained by enzymatic hydrolysis of drug-modified DNA and were characterized by high performance liquid chromatographic elution techniques. The 3,4 position represents the unique photoreactive site for benzopsoralens. Denaturation-renaturation experiments confirm that the benzoderivatives are purely monofunctional, while the tetrahydrocongeners form interstrand cross-links, even though to a remarkably lesser extent than 8-methoxypsoralen (8-MOP). The new compounds, in the presence of long-wavelength ultraviolet radiation, are very moderately effective in forming reactive oxygen species; they are ineffective in promoting oxidation of tyrosine and 3-(3,4-dihydroxyphenyl)alanine to dopachrome and melanin. Skin photosensitizing experiments on guinea pigs indicate that benzo- and tetrahydrobenzopsoralen derivatives are almost devoid of any phototoxic effects. Thus, this class of compounds appears to be interesting for the development of new, less phototoxic chemotherapeutic agents that interact with DNA better than 8-MOP.