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Biomedical subjects

G Luck

Publications and source records attributed to G Luck.

At least 19 recordsLinked to original sources
PubMed2001

Double-blind clinical trial of sertraline treatment for alcohol dependence.

Clinical studies that have evaluated serotonergic medications to reduce alcohol consumption have yielded conflicting results. These studies primarily treated patients with alcohol dependence, excluding those with a current depressive disorder, in an effort to differentiate any medication effects directly on drinking from those on mood. Yet despite the exclusion of current depression, a group of alcohol-dependent patients who are not depressed can be highly heterogeneous. For example, this subgroup can include those with a lifetime depressive disorder. If these patients were more sensitive to serotonergic medications than patients without a lifetime depressive disorder, medication effects in a subgroup of patients who were not depressed could be obscured. Thus, the purpose of this study was to examine the efficacy of sertraline for treating alcohol dependence in patient groups that were differentiated by the presence or absence of lifetime depression. This study examined the effectiveness of sertraline (200 mg/day) or placebo for 14 weeks in 100 alcohol-dependent subjects with (N = 53) or without (N = 47) a lifetime diagnosis of comorbid depression. Sertraline treatment seemed to provide an advantage in reducing drinking in alcohol-dependent patients without lifetime depression, illustrated best with a measure of drinking frequency during treatment. However, sertraline was no better than placebo in patients with a diagnosis of lifetime comorbid depression, and current depression did not change the results. Treatment with selective serotonin reuptake inhibitors may be useful in alcohol-dependent patients who are not depressed. Subtyping those with alcohol dependence on the basis of the absence versus the presence of a lifetime depressive disorder may help to resolve conflicting findings in the literature on the treatment of alcohol dependence with serotonergic medications.

Adult↗
PubMed2000

Sertraline treatment for alcohol dependence: interactive effects of medication and alcoholic subtype.

BACKGROUND: Characteristic behaviors of some alcohol-dependent individuals, e.g., binge drinking, comorbid psychopathology, and some types of alcohol-related problems, have been linked to abnormalities in serotonergic neurotransmission. However, studies that have evaluated serotonergic pharmacotherapy for reducing drinking have yielded conflicting results. One explanation for these findings is a general failure to distinguish alcohol subgroups that may be differentiated on the basis of serotonergic abnormalities. However, in 1996, Kranzler and colleagues reported that Type B alcoholics, who are characterized by high levels of premorbid vulnerability, alcohol dependence severity, and comorbid psychopathology, showed less favorable drinking outcomes in response to treatment with fluoxetine, a serotonin reuptake inhibitor, than with placebo. This medication effect was not seen in Type A alcoholics, i.e., those with lower risk/severity of alcoholism and psychopathology. The aim of the present study was to explore the validity of differential responding by alcohol-dependent subtypes using the serotonin reuptake inhibitor, sertraline. METHODS: A k-means clustering procedure was applied to a sample of alcohol-dependent subjects enrolled in a 14-week, placebo-controlled trial of 200 mg/day of sertraline, classifying them into lower-risk/severity (Type A: n = 55) and higher-risk/severity (Type B: n = 45) subgroups. RESULTS: A significant interaction between alcoholic subtype and medication condition was found, confirming the findings of Kranzler and colleagues that alcoholic subtypes responded differentially to serotonergic medication. Somewhat at variance with their results, however, the present study showed that the lower risk/severity (Type A) subjects had more favorable outcomes when treated with sertraline compared to placebo. CONCLUSIONS: Alcoholic subtypes differentially responded to sertraline when used as a treatment to reduce alcohol drinking, with one subtype having more favorable outcomes. Subtyping alcoholics may help to resolve conflicting findings in the literature on serotonergic treatment of alcohol dependence.

Adolescent↗
PubMed1999

Cotinine replacement levels for a 21 mg/day transdermal nicotine patch in an outpatient treatment setting.

This study examined plasma cotinine replacement levels of 56 outpatient smokers administered a 21 mg/day transdermal nicotine patch (Nicoderm CQ ). The percentage of cotinine replacement ranged from 35 to 232% (mean 107%; median 90.5%). Four subject variables were found to be significantly correlated with percentage of cotinine replacement-baseline cotinine level, prior quit attempts, gender, and the Fagerström Tolerance Questionnaire score. A two-variable model consisting of baseline cotinine level and gender provided the most powerful predictor combination. The percentage of cotinine replacement was not predictive of post-treatment smoking. The relatively high levels of cotinine replacement obtained using the Nicoderm CQ 21 mg/day patch suggest cautious use of higher dose treatment with this particular patch.

Administration, Cutaneous↗
PubMed1998

Clinical correlations with carbohydrate-deficient transferrin levels in women with alcoholism.

Carbohydrate-deficient transferrin (CDT) has received increasing attention as a potential biological marker for heavy drinking or as an objective marker of relapse in patients who are treated for alcohol dependence. Previous studies have demonstrated the utility of CDT among men, but there are fewer and inconsistent reports on the utility of CDT among women. This study reports in a sample of 40 alcohol-dependent women, the association between CDT levels, and several different types of measures of drinking intensity including frequency of heavy drinking. Although the majority of drinking indices correlated with CDT levels in men, among women, CDT levels were significantly correlated with the percentage of days of heavy drinking when heavy drinking day was defined as drinking 6 or more drinks per drinking day. The results also support an association between current menstrual function, CDT levels, and drinking indices. These findings suggest that the pattern of drinking (combining high frequency and high intensity) may be an important determinant of CDT levels in women with alcohol dependence, compared with men.

Adult↗
PubMed1997

On-line column-switching high-performance liquid chromatography analysis of cardiovascular drugs in serum with automated sample clean-up and zone-cutting technique to perform chiral separation.

A selective and highly reproducible, multi-column HPLC method is described for the analysis of the following cardiovascular drugs: lidocaine, pindolol, metoprolol, oxprenolol, diltiazem and verapamil, in serum. Column-switching devices are employed in combination with advanced separation media technologies for the automated analysis of samples containing complex matrices. The method consists of on-line sample clean-up using a restricted access sorbent, HPLC analysis of the drugs on a microsphere non-porous silica RP-18 column, and front-cutting to perform the chiral separation of pindolol enantiomers on a second HPLC system. Simultaneous control of the two HPLC systems and data analysis is achieved from a single centralized software. The R.S.D. values of the peak areas for spiked serum are less than 1% for metoprolol and oxprenolol, 2-5% for lidocaine, diltiazem and verapamil, and 1.2 and 2.4% for the two pindolol enantiomers. Recoveries, limits of detection and linearities are provided.

Cardiovascular Agents↗
PubMed1994

Polyphenols, astringency and proline-rich proteins.

Recent, NMR and precipitation, studies of molecular recognition of proline-rich proteins and peptides by plant polyphenols are described and rationalized. The action of polysaccharides and caseins in the moderation of the astringent response, which is engendered by polyphenols present in foodstuffs and beverages, is described. The possible influence of plant cell wall glycoproteins on the process of lignification is discussed in the light of the observed affinity of phenolic substrates for prolyl residues in protein structures.

Amino Acid Sequence↗
PubMed1993

Binding to DNA of selected lexitropsins and effects on prokaryotic topoisomerase activity.

The binding behaviour toward DNA of some minor groove binders related to distamycin was studied by means of circular dichroism. In addition their influence on the activity of topoisomerases isolated from Streptomyces noursei has been investigated. The monocationic imidazole containing ligands (lexitropsins) show a decreased affinity to AT pairs but an increased affinity to GC pairs which contrasts the AT-preferred binding of Dst-2 and Dst-3. For the monocationic triimidazole containing lexitropsin the affinity for GC over AT pairs was most pronounced. It was also found that the imidazole containing lexitropsins are inhibitors of topoisomerases. These minor groove binders interfere more strongly with the DNA gyrase activity than with the prokaryotic topoisomerase I. Our results indicate that Dst-3 most effectively inhibits gyrase and topoisomerase I activity. However, the inhibitory effect is neither related to the base pair specificity nor to the binding strength of different ligands. The mechanism of interference of minor groove binders with topoisomerase activity is more complex. It is considered that different factors, such as the nature of the ligand together with their DNA binding parameters and the target sequences of the enzymes play a role in the inhibitory effects of minor groove binders.

Animals↗
PubMed1992

DNA binding of the nonintercalative ligands SN-6132, SN-6131 and SN-6113: minor variations of the ligand structure may cause changes in the base pair preference.

The DNA binding selectivity of three ligands of a series of antitumor agents of bisquaternary ammonium heterocycles has been investigated by means of CD spectroscopy and melting measurements. From the spectroscopic results and binding data it is concluded that the agents SN-6132, SN-6131 and SN-6113 have relatively high affinity to AT base pair sequences whereas the binding to GC pairs is very low. The binding selectivity to AT base pair sequences decreases in the order netropsin > SN-6132 > SN-6113 > SN-6131. Poly(dA).poly(dT) has the highest binding preference for SN-6132 relative to that of SN-6131. The different binding behavior of the ligands is related to their distinct changes in the chemical structure and to the DNA minor groove properties which determines the adaptability of the ligands in the groove.

Antineoplastic Agents↗
PubMed1989

Variation of DNA sequence specificity of DNA-oligopeptide binding ligands related to netropsin: imidazole-containing lexitropsins.

CD binding studies of nonintercalative oligopeptides related to netropsin, named lexitropsins, have been carried out with synthetic duplex DNAs and natural DNA. While netropsin possesses a high dA.dT sequence specificity, these ligands show a progressive lowering of the ability to bind to dA.dT basepairs in DNA and a dramatic reduction of the sequence specificity seen at high salt concentration due to a replacement of pyrrole moieties by imidazoles. This variation in DNA sequence specificity of lexitropsins is mirrored in corresponding large differences in the template inactivation of poly(dA-dT).poly(dA-dT) in the RNA polymerase reaction by these drugs. The presence of imidazole permits binding of the oligopeptide to dG.dC pairs, which is most effective for the triimidazole peptide. Results at increasing salt concentration reveal, however, that a tight binding to pure dG.dC sequences does not occur. A proper sequence containing dG.dC and dA.dT pairs is supposed to be required for a higher specificity. The CD data accord well with previously reported melting studies and are in favor of recent theoretical results suggesting that the diminished AT preference may be due to an increase in the complexation energy with the dG.dC pairs.

Base Composition↗
PubMed1987

Interaction of the nonintercalative antitumour drugs SN-6999 and SN-18071 with DNA: influence of ligand structure on the binding specificity.

Binding to DNA's of the non-intercalative ligands SN-6999 and SN-18071 has been studied by means of circular dichroism, UV absorption, thermal melting and for SN-6999 by viscosity measurements. Both antitumour drugs show a preference for dA.dT rich DNA's, but the base pair selectivity of SN-18071 is lower as indicated by some affinity to dG.dC containing duplex DNA. The dA.dT base pair specificity of SN-6999 is comparable to that of netropsin. It forms very stable complexes with dA.dT containing duplex DNA and competes with netropsin binding on DNA. The ligands SN-18071 and pentamidine are totally released from their complexes with poly(dA-dT).poly(dA-dT) by competitive netropsin binding. The results demonstrate that hydrogen bonding capacity of the ligand in addition to other factors strongly contribute to the base sequence specificity in the recognition process of the ligand with DNA. A binding model of SN-6999 with five dA.dT pairs in the minor groove of B-DNA is suggested.

Antineoplastic Agents↗
PubMed1985

Two binding modes of netropsin are involved in the complex formation with poly(dA-dT).poly(dA-dT) and other alternating DNA duplex polymers.

Using CD measurements we show that the interaction of netropsin to poly(dA-dT).poly(dA-dT) involves two binding modes at low ionic strength. The first and second binding modes are distinguished by a defined shift of the CD maximum and the presence of characteristic isodichroic points in the long wavelength range from 313 nm to 325 nm. The first binding mode is independent of ionic strength and is primarily determined by specific interaction to dA.dT base pairs. Employing a netropsin derivative and different salt conditions it is demonstrated that ionic contacts are essential for the second binding mode. Other alternating duplexes and natural DNA also exhibit more or less a second step in the interaction with netropsin observable at high ratio of ligand per nucleotide. The second binding mode is absent for poly(dA).poly(dT). The presence of a two-step binding mechanism is also demonstrated in the complex formation of poly(dA-dT).poly(dA-dT) with the distamycin analog consisting of pentamethylpyrrolecarboxamide. While the binding mode I of netropsin is identical with its localization in the minor groove, for binding mode II we consider two alternative interpretations.

Binding Sites↗
PubMed1984

Interaction of nucleic acids with a non-intercalative anti-leukemic compound containing bisquarternary heterocycles.

The binding of an antitumour drug with bisquarternary ammonium heterocyclic structure, NSC-101327, to nucleic acids has been examined by using ultraviolet absorption and CD measurements. Like the minor groove-binding oligopeptides, netropsin and distamycin A, the optically inactive chromophoric system of NSC-101327 shows induced Cotton effects in the CD spectra of complexes with various DNAs, RNA and single-stranded polynucleotides. This property directly reflects interaction of NSC-101327 with different types of nucleic acids at moderate ionic strength, which contrasts with previous findings of a higher selective binding of netropsin to B-DNA. However, an efficient interactin of NSC-101327 with dA X dT basepair sequences is demonstrated by a large melting temperature increase of dA X dT-rich DNAs. NSC-101327 also reacts with dG X dC base pairs of B-DNA and forms a complex with Z-DNA of poly( br8dG -dC) X poly( br8DG -dC). The affinity of NSC-101327 to poly(dG-dC) X poly(dG-dC) is, however, lower, and the CD spectral binding effect depends on the ionic strength. The CD results of the complex with poly(dA-dT) X poly(dA-dT) suggests at least two binding modes, in accordance with previous conclusions. This is indicated by a clear-cut initial increase of the CD signal and a subsequent large decrease to negative CD signals. Competition experiments with netropsin suggest that binding of NSC-101327 occurs preferentially in the minor groove without intercalation. NSC-101327 also tends to interact with lower binding affinity to dG-dC pairs in B-DNA, with rA X rU pairs of RNA and with single-stranded polynucleotides. Thus our results suggest that NSC-101327 represents a DNA groove-binding ligand of lower basepair specificity and lower conformational selectivity compared to the B-specific netropsin probe.

Antineoplastic Agents↗
PubMed1983

Chain length-dependent association of distamycin-type oligopeptides with A X T and G X C pairs in polydeoxynucleotide duplexes.

Different binding affinities of various distamycin analogs including the deformylated derivative with poly(dA-dC) X poly(dG-dT) were investigated using CD measurements. The inhibitory effect of distamycins on the DNAase I cleavage activity of DNA duplexes strongly supports the binding data. The base specificity of the ligand interaction with duplex DNA depends on the chain length of distamycin analogs. Netropsin, distamycin-2 and the deformylated distamycin-3 show no binding to dG X dC containing sequences at moderate ionic strength and are classified as highly dA X dT specific. In contrast distamycin having three, four or five methylpyrrolecarboxamide groups also forms more or less stable complexes with dG X dC-containing duplexes. These ligands possess a lower basepair specificity. The correlation between binding behavior and oligopeptide structure shows that presence of the number of hydrogen acceptor and donor sites determines the basepair and sequence specificity. The additional interaction with dG X dC pairs becomes essential when the number of hydrogen acceptor sites exceeds n = 3.

Animals↗
PubMed1980

Protection of (dA.dT) cluster regions in the DNAase I cleavage of DNA by specific interaction with netropsin.

The specific DNA binding ligand netropsin selectively blocks dA-dT base pairs in clusters containing two or more consecutive thymine residues at the dNAase I cleavage sites of DNA. Using CD and UV absorption measurements it is shown, that at various ratios of netropsin to nucleotide concentrations and even at satuation of ligand interaction the enzyme cuts along regions containing dG-dC pairs sandwiched between dA-dT pairs. This follows a slow kinetics and is associated with a release of netropsin from those segments. These facts suggests the usefulness of the partial protection of certain DNA sequences in DNAase I cleavage sites in producing DNA fragments in structural studies of the genome. A possible interpretation of the effect of netropsin binding on the enzymatic hydrolysis of phosphodiester bonds of the helix is discussed.

Animals↗
PubMed1980

Magnetic circular dichroism study of the binding of netropsin and distamycin A with DNA.

The magnetic circular dichroism (MCD) of netropsin and distamycin-A is reported. New data for the interaction with dA ; dT base pairs in DNA were obtained from the MCD of their complexes with DNA duplex polymers. The MCD results allow an interpretation of the induced Cotton effects in the natural CD spectra of netropsin and distamycin-A complexes with DNA. While large distortions of the bases in DNA by the oligopeptide interaction is excluded, some subtle conformational variations of the DNA might explain the inhibition of the enzyme function of netropsin and distamycin-A on DNA.

Circular Dichroism↗
PubMed1980

Studies on synthesis and CD properties of complementary and self-complementary deoxyoligonucleotides.

Two types of deoxyoligonucleotides, a nona- and two dodecamers have been synthesized as a basis of various aspects in structural and functional studies of the DNA. Using different methodological approaches highly purified deoxyoligomers were obtained and characterized by UV absorption and CD measurements. As an example the results presented are concerned with the synthesis of the following dodecanucleotide containing the recognition site of Hind III : dC-A-C-A-A-G-C-T-T-G-T-G. CD properties and some structural related effects of two complementary and a selfcomplementary deoxyoligomers are described.

Base Sequence↗
PubMed1980

[Nucleotide specificity of sibiromycin interaction with DNA].

Sibiromycin binds selectively to poly(dG).poly (dC) and poly(dG--dC).poly (dG--dC) and does not interact with poly(dA--dT).poly(dA--DT), poly (dI).poly (dC) and poly(dI--dC).poly(dI-dC) as is evident from the changes in the UV spectrum of the antibiotic at 310 mn, differential CD spectrum and inhibition of the template activity of polynucleotides in the DNA-dependant RNA-polymerase system. Sibiromycin efficiently interacts with GC-rich DNA specifically methylated at N-7 of guanine and glucosilated DNA of T2 phage. Therefore, specific interaction of sibiromycin with the guanine sites may take place rather in the narrow groove than in the large groove of the double helix.

Aminoglycosides↗