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Biomedical subjects

M Palumbo

Publications and source records attributed to M Palumbo.

At least 91 records · Page 5Linked to original sources
PubMed1995

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.

Adolescent↗
PubMed1994

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.

Amsacrine↗
PubMed1994

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.

Anthracenes↗
PubMed1994

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.

Base Sequence↗
PubMed1994

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).

Adult↗
PubMed1994

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.

Animals↗
PubMed1993

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.

Animals↗
PubMed1993

Phase I-II intraperitoneal mitoxantrone in advanced pretreated ovarian cancer.

36 previously treated patients (25 with anthracyclines) with advanced epithelial ovarian cancer have been treated with intraperitoneal (i.p.) mitoxantrone (M) at increasing doses. The response was evaluated through repeated laparoscopy with multiple biopsies and serial measurement of Ovarian Cancer Antigen 125 (CA 125); 11/36 patients had a complete (6 patients) or partial (5 patients) response. Toxicity (both local and general) was observed starting from 25 mg/m2 of M per cycle. The amount of drug reaching systemic circulation was monitored by measuring M plasma value after i.p. treatment. This study showed wide variations in serum levels obtained after i.p. doses ranging from 23 to 36 mg/m2. The area under the curve (AUC) of mitoxantrone plasma samples, did not correlate with the i.p. administered dose. Conversely, a correlation seems to exist between the plasma AUC and the responder status. Patients who showed clinical responses to i.p. treatment with mitoxantrone had AUCs and plasma peak levels of the drug that were significantly higher than those in non-responders (P = 0.03, Fisher's exact test).

Adult↗
PubMed1993

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.

4-Quinolones↗
PubMed1993

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.

Benzene Derivatives↗
PubMed1993

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.

Animals↗
PubMed1993

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.

Animals↗
PubMed1992

Sequence specificity of psoralen photobinding to DNA: a quantitative approach.

The effects of different DNA sequences on the photoreaction of various furocoumarin derivatives was investigated from a quantitative point of view using a number of self-complementary oligonucleotides. These contained 5'-TA and 5'-AT residues, having various flanking sequences. The furocoumarins included classical bifunctional derivatives, such as 8-methoxy- and 5-methoxypsoralen, as well as monofunctional compounds, such as angelicin and benzopsoralen. Taking into an account the thermodynamic constant for noncovalent binding of each psoralen to each DNA sequence, the rate constants for the photobinding process to each fragment were evaluated. The extent of photoreaction is greatly affected by the DNA sequence examined. While sequences of the type 5'-(GTAC)n are quite reactive towards all furocoumarins, 5'-TATA exhibited a reduced rate of photobinding using monofunctional psoralens. In addition terminal 5'-TA groups were the least reactive with 5- and 8-methoxypsoralen, but not with angelicin or benzopsoralen. Also 5'-AT-containing fragments exhibited remarkably variable responses toward monofunctional or bifunctional psoralen derivatives. As a general trend the photoreactivity rate of the former is less sequence-sensitive, the ratio between maximum and minimum being less than 2 for the examined fragments. The same ratio is about 3.4 for 8-methoxypsoralen and 6.2 for 5-methoxypsoralen. This approach, in combination with footprinting studies, appears to be quite useful for a quantitative investigation of the process of covalent binding of psoralens to specific sites in DNA.

Base Sequence↗
PubMed1992

Quinolone binding to DNA is mediated by magnesium ions.

The binding of plasmid DNA to norfloxacin, a quinolone antibacterial agent, was investigated by fluorescence, electrophoretic DNA unwinding, and affinity chromatography techniques. The amount of quinolone bound to DNA was modulated by the concentration of Mg2+. No interaction was evident in the absence of Mg2+ or in the presence of an excess of Mg2+, whereas maximum binding was observed at a Mg2+ concentration of 1-2 mM. The experimental data can be fitted to the formation of three types of Mg adducts: a binary adduct with norfloxacin and Mg2+, a binary adduct with DNA and Mg2+, and a ternary adduct with quinolone, plasmid, and Mg2+. We propose a model for the ternary complex, in which Mg acts as a bridge between the phosphate groups of the nucleic acid and the carbonyl and carboxyl moieties of norfloxacin. Additional stabilization may arise from stacking interactions between the condensed rings of the drug and DNA bases (especially guanine and adenine), which may account for the preference exhibited by quinolones for single-stranded and purine-rich regions of nucleic acids. Other possible biochemical pathways of drug action are suggested by the observation that norfloxacin binds Mg2+ under conditions that are close to physiological.

Chromatography, Affinity↗
PubMed1992

Water-soluble polysaccharide-anthracycline conjugates: biological activity.

The anticancer agents doxorubicin and daunorubicin were covalently linked to the water-soluble anionic polysaccharides hyaluronic acid and carboxy-methylcellulose. The drug-polymer conjugates are in principle prevented from entering cells, can efficiently bind to cell surfaces and allow precise dose-response determinations. In addition, they are not able to bind DNA because of their negative charge. Cell growth and DNA synthesis inhibition studies indicated decreased cell toxicity for the polymer conjugates. The mol. wt of the carrier was shown to affect the biological activity of the anthracycline to a moderate extent. Partial drug incorporation into cells was observed as a function of time, probably due to endocytosis phenomena followed by biochemical cleavage of the conjugate. The conclusion was drawn that membrane binding appears to contribute to total toxicity only to a minor extent.

Carboxymethylcellulose Sodium↗
PubMed1991

The peculiar binding properties of 4'-deoxy,4'-iododoxorubicin to isolated DNA and 175 bp nucleosomes.

The thermodynamic parameters governing the interaction of 4'-deoxy,4'-iododoxorubicin (4'-IAM) to double stranded DNA or 175 bp nucleosomes have been evaluated at different ionic strength and temperature conditions by means of fluorescence techniques. The iodo-anthracycline exhibits quite different characteristics from the parent compounds adriamycin (AM) and daunomycin (DM) and other second generation derivatives. In fact, the contribution of electrostatic interactions to the total free energy of binding is rather poor and the changes in enthalpy, usually high and negative, are low and eventually positive. Unlike other members of its family, 4'-IAM exhibits preference for the nucleosomal structure. In addition, its binding to isolated DNA is remarkably cooperative. Circular dichroism studies show changes in the geometry of the intercalation complex when the drug binds to nucleosomes. The possibility for the iodo-sugar moiety to act as an alkylating or free-radical producing species was also considered as an alternative mechanism of action. However, no evidence was obtained to support these hypotheses. Thus the major differences observed in DNA-binding in comparison to parent anthracyclines appear to be mostly related to the lower pKa and higher lipophilicity exhibited by 4'-IAM.

Animals↗
PubMed1991

Interaction between second generation anthracyclines and DNA in the nucleosomal structure.

The interaction between three anthracycline antibiotics of second generation (9-deoxydoxorubicin, 9-DAM, 4-demethoxydaunorubicin, 4-DDM, 4'-deoxydoxorubicin, 4'-DAM) and DNA in the nucleosomal structure was investigated using fluorescence and circular dichroism techniques. The thermodynamic parameters of the binding process were obtained at different ionic strength and temperature conditions, thus allowing the calculation of the electrostatic contribution to the free energy and the enthalpy of the process. The same measurements were performed on linear double stranded DNA for comparison. The parent compounds adriamycin and daunomycin were additionally considered. Although the examined drugs greatly vary in biological activity, their binding parameters are only slightly different. Like the parent compounds, 9-DAM, 4-DDM and 4'-DAM exhibit preference for isolated regions of the polynucleotide rather than for nucleosomes. This fact suggests a non-homogeneous distribution of the antibiotics in vivo. The enthalpy values are remarkably lower than the ones characterizing the interaction of adriamycin and daunomycin to DNA. According to CD spectra, all derivatives, but 4-DDM, intercalate into nucleosomal or free DNA in a manner similar to the first generation compounds, namely with the chromophore perpendicular to the hydrogen bonds between the bases. The demethoxy compound, on the other hand, seems to be able to insert its planar moiety in different orientations, which are related to the structure of the nucleic acid being examined. The lack of the methoxy group in the intercalating part of the molecule appears to be responsible for this behaviour. As far as biological activity is concerned, our findings indicate a qualitative correlation between cell cytotoxicity and ability of interaction with nucleosomes at physiological conditions, rather than with free DNA. The modified binding stereochemistry of 4-DDM could play an additive role in modulating the pharmacological effectiveness of the above compounds.

Animals↗