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Polymorphisms in the IGF-1 and IGFBP 3 promoter and the risk of breast cancer.

Binding of IGF-1 to the type I IGF receptor starts a signalling cascade that plays an important role in regulating cell proliferation, differentiation and apoptosis. The interaction between the IGF-1 and its receptor is mainly regulated by a binding protein, IGFBP 3. We studied a CA repeat polymorphism 969 bp upstream of the transcription start site in the IGF-1 gene and an A-202 C polymorphism in the IGFBP 3 gene and tested their association with breast cancer risk using four case-control series with a total of 787 cases and 900 controls. We did not find any association between the breast cancer risk and the IGF-1 repeat length (19 versus non-19) or the IGFBP 3 A-202 C polymorphism in the postmenopausal breast cancer series or in women diagnosed for breast cancer under the age of 50. In the familial breast cancer series we observed a non-significantly increased odds-ratio (OR) in homozygotes for the non-19 alleles of the IGF-1 gene (OR 1.51, 95% CI 0.96-2.39, p=0.07). Similarly, in the familial breast cancer series we detected an increased frequency of the IGFBP 3 -202 C allele carriers (OR 1.50, 95% CI 1.05--2.14, p=0.03). The association was stronger in individuals homozygous for these alleles (OR 3.76, 95% CI 1.44-v-9.81, p=0.006). Thus, the polymorphisms in the IGF-1 and IGFBP 3 genes associated with an increased risk of breast cancer in familial cases carrying the variant alleles.

Adult↗

Estimation of interaction between human keratinocytes and xenogenic collagen in vitro.

This paper describes the interaction observed between human keratinocytes and xenogenic collagen in vitro modified by HCl. Human keratinocytes were cultivated for 3-10 days, on modified and control support. Their growth, morphology and interaction with support were analyzed. It was found that on both control and experimental (modified) collagen cells proliferated in a similar way. Within 3-10 days, the culture became multilayered and mature and differentiation of cells was visible. Using electron microscope elements of basal membrane interacting with support were seen. On modified support processes of cells penetrating the support are occasionally seen. By use of the immunofluorescent, cytochemical techniques was found the presence of: BP-180 (antigen), beta(4) integrin, laminin 5 and collagen IV, VII, VIIc. On the modified support the above listed elements appeared between 3 and 7 days of culture, whereas on the control between 7th and 10th days. On 10th day of culture, the presence of elements of basal membranes became less evident. Results give some hope for using xenogenic, modified collagen as support of keratinocytes culture in process of human skin engineering.

Adult↗

Ataxia and oculomotor apraxia caused by a large-scale deletion in the senataxin gene.

Senataxin, an RNA/DNA helicase, is a key protein providing genome stability and one of the best characterized R-loop-binding factors playing an important role in transcription and DNA repair processes. Pathogenic SETX gene variants cause autosomal recessive spinocerebellar ataxia with axonal neuropathy (AOA2, MIM #606002) and autosomal dominant juvenile amyotrophic lateral sclerosis (ALS4, MIM #602433), rare neurodegenerative disorders characterized by juvenile onset of progressive cerebellar ataxia, axonal sensorimotor peripheral neuropathy, combined upper and lower motor neuron symptoms, and increased serum alpha-fetoprotein (AFP; specific for AOA2). We report two cases of adult patients presenting with cerebellar syndrome, scanned speech, and exercise intolerance which started in the second/third decade of life and were followed by muscle weakness and impaired gait coordination. Whole exome sequencing (WES) was performed to analyze single nucleotide and copy number variants. A decreased coverage of a genomic region of around 16 kb on chromosome 9 (chr9:132,295,852-132,311,876), suggesting a deletion encompassing 5 exons of the SETX gene (exons 11-15, NM_015046.7) was observed. This homozygous SETX (9q34.13) deletion leads to a frame shift and consequently truncation of the helicase domain in the protein. Loss-of-function variants in the SETX gene are known to be pathogenic. Statistical analysis of NGS data from the Polish population identified a few heterozygous carriers, suggesting its region-specific origin.

Humans↗

Ceramides and glycosphingolipids in maturation process: leukemic cells as an experimental model.

Leukemic cells were used as experimental material to demonstrate changes in the content of GSLs during the development and maturation of neutrophils. The most abundant cellular GSL is LacCer. An elevation in the LacCer level occurs twice during the maturation process: initially, on formation of azurophil granules, and subsequently, (a more significant rise) on formation of specific granules. The formation of the latter is accompanied by an increase in the level of GalGalCer. During the maturation of myeloblasts, there is a simultaneous growth in the content of LacCer and GM3 as well as that of their common precursors, that is, free ceramides. Like other tumor cells, GM3 rich myeloblasts in the peripheral blood from patients with AML are characterized by shedding of gangliosides. The quantitative Cer/GlcCer ratio in these cells seems to be advantageous for the efficacy of chemotherapy in the induction of apoptosis. Myelo- and metamyelocytes achieve the highest level of GSLs. Their entry into the full maturity stage is accompanied by a decrease in the level of GSLs. Patterns of GSLs expression change greatly during development and maturation. However, with respect to the composition and content of GSLs, there are no significant differences between normal and leukemic mature neutrophils. At each stage of the development and maturation of myelogenous leukemic cells, as well as in normal mature neutrophils, there occurs the synthesis of the same molecular species both free ceramides and ceramide portions of LacCer, precursor of more complex GSLs.

Case-Control Studies↗

Novel, flexible, and conformationally defined analogs of gepirone: synthesis and 5-HT1A, 5-HT2A, and D2 receptor activity.

Novel, flexible arylpiperazine gepirone analogs (1a-3a) with a mixed 5-HT1A/5-HT2A receptor profile, low D2 receptor affinity, and agonistic (2a) or partial agonistic (1a, 3a) activity toward 5-HT1A receptor sites were synthesized. Their conformationally restricted counterparts (1b-3b) were selective 5-HT1A ligands (over 5-HT2A and D2 receptors), which turned out to be agonists (2b, 3b), or partial agonist (1b) of 5-HT1A receptors.

Animals↗

1-Aryl-4-(4-succinimidobutyl)piperazines and their conformationally constrained analogues: synthesis, binding to serotonin (5-HT1A, 5-HT2A, 5-HT7), alpha1-adrenergic, and dopaminergic D2 receptors, and in vivo 5-HT1A functional characteristics.

Starting with the structure of potent 5-HT(1A) ligands, that is, MM77 [1-(2-methoxyphenyl)-4-(4-succinimidobutyl)piperazine, 4] and its constrained version 5 (MP349), previously obtained in our laboratory, a series of their direct analogues with differently substituted aromatic ring (R=H, m-Cl, m-CF(3), m-OCH(3), p-OCH(3)) were synthesized. The flexible and the corresponding 1e,4e-disubstituted cyclohexane derivatives were designed in order to investigate the influence of rigidification on 5-HT(1A) affinity, selectivity for 5-HT(2A), 5-HT(7), D(1), and D(2) binding sites and functional profile at pre- and postsynaptic 5-HT(1A) receptors. The new compounds 19-25 were found to be highly active 5-HT(1A) receptor ligands (K(i)=4-44 nM) whereas their affinity for other receptors was: either significantly decreased after rigidification (5-HT(7)), or controlled by substituents in the aromatic ring (alpha(1)), or influenced by both those structural modifications (5-HT(2A)), or very low (D(2), K(i)=5.3-31 microM). Since a distinct disfavor towards rigid compounds was observed for 5-HT(7) receptors only, it seems that the bioactive conformation of chain derivatives at those sites should differ from the extended one. Several in vivo models were used to asses functional activity of 19-25 at pre- (hypothermia in mice) and postsynaptic 5-HT(1A) receptors (lower lip retraction in rats and serotonin syndrome in reserpinized rats). Unlike the parent antagonists 4 and 5, all the new derivatives tested were classified as partial agonists with different potency, however, similar effects were observed within pairs (flexible and rigid) of the analogues. The obtained results indicated that substitution in the aromatic ring, but not spacer rigidification, controls the 5-HT(1A) functional activity of the investigated compounds. Moreover, an o-methoxy substituent in the structure of 5 seems to be necessary for its full antagonistic properties. Of all the new compounds studied, trans-4-(4-succinimidocyclohexyl)-1-(3-trifluoromethylphenyl)piperazine 24 was the most potent 5-HT(1A) receptor ligand in vitro (K(i)=4 nM) and in vivo, with at least 100-fold selectivity for the other receptors tested.

Animals↗

Structure-intrinsic activity relationship studies in the group of 1-imido/amido substituted 4-(4-arylpiperazin-1-yl)cyclohexane derivatives; new, potent 5-HT1A receptor agents with anxiolytic- like activity.

Introduction of 1,4-disubstituted cyclohexane ring in the structure of flexible long chain arylpiperazines resulted in linearly constrained, potent serotonin (5-HT)(1A) ligands. In order to trace structure-intrinsic activity relationships in this group, a new series of 1-substituted 4-(4-arylpiperazin-1-yl)cyclohexane derivatives with different cyclic imide/amide termini, and their flexible, tetramethylene analogues were synthesized and pharmacologically evaluated for 5-HT(1A) receptors. In vitro binding experiments revealed that all the compounds were potent 5-HT(1A) receptor agents (K(i) = 1.9-74 nM). Some derivatives tested additionally showed also high affinity for alpha(1)-adrenergic receptors (K(i) = 2.9-101 nM) and for 5-HT(7) receptors. Functional in vivo examination revealed that rigid ligands with o-OCH(3) group in the aryl moiety and cyclic imide system in the opposite terminal behaved like postsynaptic 5-HT(1A) receptor antagonists. On the other hand, unsubstituted, m-Cl, or m-CF(3) substituted derivatives as well as those with cyclic amide group in the terminal fragment exhibited agonistic or partial agonistic activity. Three out of four derivatives tested, that is, postsynaptic 5-HT(1A) antagonists 9 and 10, and partial agonist 16, showed anxiolytic-like activity in the conflict drinking (Vogel) test in rats.

Adrenergic alpha-Agonists↗

Seasonal changes in brain melatonin concentration in the three-spined stickleback (Gasterosteus aculeatus): towards an endocrine calendar.

Pineal organ and its hormone melatonin (N-acetyl-5-methoxytryptamine) is likely involved in timing and synchronisation of many internal processes, such as reproduction, with annual changes in environmental cues, i.e., photoperiod and water temperature. The seasonal changes in melatonin profile in stickleback brains related to the following reproductive phases were examined, and the link between melatonin concentrations and the stages of spawning cycle was analysed. Two wild populations of sticklebacks were exposed to annual environmental changes in their natural habitats. Brains, gonads, kidneys and livers were collected over 2 years. Melatonin was measured using RIA and the indices, gonadosomatic (GSI), nephrosomatic (NSI) and hepatosomatic (HSI), were calculated. The role of melatonin, as a component of internal calendar engaged in the control of seasonal breeding in this species, is discussed. The extremely high melatonin levels observed in early spring (March) and autumn (October) seem to mark out a time frame for spawning in sticklebacks. The seasonal pattern of melatonin production and identified development stages of gonads suggests the potential inhibitory effect of the hormone on stickleback reproduction in shortening photoperiod and stimulatory effect in lengthening photoperiod.

Animals↗

Influence of exogenous thyroxine on plasma melatonin in juvenile Atlantic salmon (Salmo salar).

One of the most clearly defined endocrine changes during the parr-smolt transformation of anadromous salmonids is an increase in plasma levels of thyroid hormones. The role of pineal hormone melatonin in timing and synchronisation of smoltification is widely discussed. The effect of administration of exogenous thyroxine (T4) on plasma melatonin was investigated in juvenile Atlantic salmon (Salmo salar) at the early stages of parr-smolt transformation. Fish were kept in fresh water under simulated-natural photoperiod and exposed to exogenous T4. Fish were sampled at 12.00 and 24.00 h from treatment and control tanks, 2 and 14 days after treatment started. Plasma melatonin and L-thyroxine were measured using RIA and competitive enzyme immunoassay, respectively. After 2 days of T4 treatment, marked difference in plasma melatonin concentration measured at 12.00 and 24.00 h was still observed in both groups. However, 2-week exposure to T4 caused a reduction in night-time plasma melatonin level and thus, probably, inhibited melatonin related time-keeping system in juvenile salmon. Additional studies are needed to clarify the mechanism of the described phenomenon.

Animals↗

Activation of the NF-kappaB system in peripheral blood leukocytes from patients with chronic heart failure.

AIM: To evaluate the activation of transcriptional nuclear factor kappa-B (NF-kappaB) in peripheral blood leukocytes (PBL) from patients with chronic heart failure (CHF). In vitro experiments were used to elucidate the role of lipopolysaccharide (LPS) as a stimulus for the NF-kappaB system in PBL. METHODS AND RESULTS: We examined 46 CHF patients (age: 62+/-1 years, LVEF: 31+/-1%, NYHA class: 2.7+/-0.1), 11 coronary artery disease (CAD) patients without CHF, and 13 healthy young subjects. The immunocytochemical localisation of NF-kappaB in PBL was assessed using a polyclonal rabbit IgG anti-c-Rel-subunit antibody. NF-kappaB activation was expressed as the percentage of PBL nuclei stained positively for c-Rel (NF-kappaB+cell). PBL from healthy controls were exposed in vitro to the following concentrations of LPS from Escherichia coli (strain O111:B4): 0.1, 10 and 5000 ng/mL. CHF patients demonstrated the highest NF-kappaB activation in PBL (NF-kappaB+cells [%]: 37.1+/-1.5) as compared to CAD patients (29.1+/-3.0%) and controls (12.6+/-1.5%) (all p<0.05). There were three main clinical determinants of NF-kappaB activation in PBL from CHF patients: peak oxygen consumption (r=0.53, p=0.025), presence of peripheral oedema (r=0.37, p<0.05) and serum C-reactive protein (r=0.40, p=0.02). In PBL from healthy subjects, LPS at all concentrations increased NF-kappaB activity towards the pattern detected in CHF. CONCLUSIONS: The NF-kappaB system is highly overactive in PBL from CHF patients. LPS at low concentrations in peripheral blood may be involved in NF-kappaB activation in PBL, and is a potential target for future therapeutic applications.

Case-Control Studies↗

Synthesis and 5-HT(1A), 5-HT(2A) receptor activity of new beta-tetralonohydantoins.

A series of new 3-[4-(4-arylpiperazinyl)-butyl]-beta-tetralonohydantoins (8a-13a) were synthesized. The compounds exhibited high affinity for 5-HT(1A) receptors (K(i)=6 to 55 nM) combined with moderate-to-high 5-HT(2A) receptor affinities (K(i)=45 to 213 nM). The results of in vivo studies indicated that of the compounds tested, 3-[4-(4-phenylpiperazinyl)-butyl-beta-tetralonohydantoin (8a) showed features of full (pre- and postsynaptic) 5-HT(1A) receptor agonists, whereas compounds 9a-13a behaved like antagonists of postsynaptic 5-HT(1A) receptors; additionally, compound 13a produced an effect characteristic of presynaptic 5-HT(1A) receptor agonists. Moreover, compounds 8a and 10a-13a exhibited properties of 5-HT(2A) receptor antagonists. Due to the most interesting 5-HT(1A)/5-HT(2A) functional profile compounds 8a and 13a were further tested for their potential psychotropic activity. In fact, compound 8a (but not 13a) showed diazepam-like anxiolytic activity and behaved like a weak antidepressant.

Animals↗

Effect of combined administration of 5-HT1A or 5-HT1B/1D receptor antagonists and antidepressants in the forced swimming test.

In the present study, we examined effects of the selective serotonin (5-hydroxytryptamine, 5-HT) reuptake inhibitor citalopram, the 5-HT/noradrenaline reuptake inhibitor imipramine, the selective noradrenaline reuptake inhibitor desipramine or the monoamine oxidase-A inhibitor moclobemide, administered in combination with the 5-HT(1A) receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridynyl)cyclohexanecarboxamide (WAY 100635) or the 5-HT(1B/1D) receptor antagonist N-[4-methoxy-3-(4-methyl-1-piperazinyl)phenyl]-2'-methyl-4'-(5-methyl-[1,2,4]oxadiazol-3-yl)1,1'-biphenyl-4-carboxamide (GR 127935) and the 5-HT(1B) receptor antagonist N-[3-(2-dimethylamino) ethoxy-4-methoxyphenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)-(1,1'-biphenyl)-4-carboxamide (SB 216641) in the forced swimming test in rats. When given alone, citalopram (20 and 30 mg/kg), imipramine (20 mg/kg), desipramine (20 mg/kg), moclobemide (20 mg/kg), WAY 100635 (0.1 and 1 mg/kg), GR 127935 (10 and 20 mg/kg) or SB 216641 (2 mg/kg) did not shorten the immobility time of rats. Co-administration of WAY 100635 (0.1 and 1 mg/kg) and citalopram (20 mg/kg), or imipramine (20 mg/kg), or moclobemide (20 mg/kg) did not affect the immobility time of rats, whereas WAY 100635 given jointly with desipramine (20 mg/kg) induced a weak anti-immobility effect. GR 127935 (10 and 20 mg/kg) or SB 216641 (2 mg/kg) co-administered with imipramine, desipramine or moclobemide, but not citalopram, produced a significant anti-immobility action in the forced swimming test in rats. These results indicate that the blockade of 5-HT(1B) rather than 5-HT(1A) receptors may facilitate the anti-immobility effect of imipramine, desipramine or moclobemide in the forced swimming test. No interaction was observed between 5-HT(1A) or 5-HT(1B/1D) receptor antagonists and citalopram.

Adrenergic Uptake Inhibitors↗

Antidepressant-like effect of the selective 5-HT1B receptor agonist CP 94253: a possible mechanism of action.

The mechanism of the antidepressant-like activity of the selective 5-hydroxytryptamine(1B) (5-HT(1B)) receptor agonist 5-propoxy-3-(1,2,3,6-tetrahydro-4-pyridinyl)-1H-pyrrolo[3,2-b]pyridine (CP 94253) was studied in the forced swimming test in mice. CP 94253 administered intraperitoneally at a single dose of 5 mg/kg potently shortened the immobility time of mice. The anti-immobility effect of CP 94253 was wholly blocked by the selective 5-HT(1B) receptor antagonist N-[3-(2-dimethylamino)ethoxy-4-methoxyphenyl]-2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)-(1,1'-biphenyl)-4-carboxamide (SB 216641, 5 mg/kg), the dopamine D2-like receptor antagonist sulpiride (50 mg/kg) and the alpha(2)-adrenoceptor antagonist idazoxan (2 mg/kg), but was not modified in animals with a lesion of the 5-HT system produced by p-chlorophenylalanine (p-CPA, 3 x 300 mg/kg). The obtained results suggest that the anti-immobility effect of CP 94253 is mediated by activation of 5-HT(1B) receptors-most probably located postsynaptically and/or as heteroreceptors, and that the dopamine and the noradrenaline systems are involved in this action.

Adrenergic alpha-Antagonists↗

Enhancement of the anti-immobility action of antidepressants by a selective 5-HT7 receptor antagonist in the forced swimming test in mice.

Using the forced swimming test in mice, we examined the effect of the following antidepressants: citalopram, imipramine, desipramine and moclobemide (which are characterized by different mechanisms of action), administered in combination with the selective 5-HT7 receptor antagonist (2R)-1-[(3-hydroxyphenyl)sulfonyl]-2-[2-(4-methyl-1-piperidinyl)ethyl]-pyrrolidine (SB 269970). All those drugs were given in doses which did not shorten the immobility time of mice. Citalopram (1.25 mg/kg), imipramine (10 mg/kg), desipramine (5 mg/kg) or moclobemide (10 mg/kg) administered jointly with SB 269970 (5 mg/kg), produced a significant antidepressant-like effect. None of the compounds studied, given alone or in combination, increased the spontaneous locomotor activity of mice. The obtained results indicate that blockade of 5-HT7 receptors may facilitate the anti-immobility effect of antidepressants in mice.

Adrenergic Uptake Inhibitors↗

Adults with Ebstein's anomaly--Cardiopulmonary exercise testing and BNP levels exercise capacity and BNP in adults with Ebstein's anomaly.

INTRODUCTION: Ebstein's anomaly is defined as the significant apical displacement of the part of the tricuspid valve causing significant tricuspid regurgitation and reduction of the functional right ventricle. The aim of the study was to evaluate exercise capacity with cardiopulmonary stress testing and to determine plasma BNP levels in adults with Ebstein's anomaly, and to establish their relation with echocardiogaphic grading of the lesion severity. MATERIALS AND METHODS: Study group consisted of 21 patients (16 males, aged 40.3+/-11.5 years). The control group: 19 healthy individuals (13 males, aged mean 39.9+/-9.3 years). On echocardiography the grade of the lesion severity was calculated (EGE) and used to define the following four groups: I < 0.5, II: 0.5-0.9, III: 1.0-1.49, IV > 1.5. The forced vital capacity (FVC), first second forced expiratory volume (FEV1), peak oxygen uptake (peak VO2), and VE/VCO2 slope were assessed with cardiopulmonary stress test and plasma BNP levels measured with radioimmunometric assay. RESULTS: In the studied group VO2 was lower than in control (21.9+/-5.4 vs. 33.6+/-8.3 mL/kg/min [p = 0.00001]), VE/VCO2 slope was higher in Ebstein's group (40.1+/-8.1, p = 0.00001). BNP levels were higher in the Ebstein group then in controls (35.9+/-25.0 vs. 17.2+/-9.9 pg/mL [p = 0.0002]) and did not differ significantly between EGE groups. PeakVO2 of 24.5+/-3.9 in patients from II EGE group were higher than in patients from EGE groups: III (17.2+/-5.2 p = 0.007) and IV (22.9+/-4.7 p = 0.05). CONCLUSIONS: Exercise capacity of adults with Ebstein's anomaly is significantly reduced and plasma BNP levels are higher compared to healthy individuals. Exercise capacity in patients with Ebstein's anomaly becomes gradually lower alongside the EGE severity; however, BNP levels do not correlate significantly with this parameter.

Adult↗

From regionalization to homogenization: Nationwide metagenomic assessment of priority pathogens and the resistome in Polish hospital wastewater.

Hospital wastewater (HWW) is a critical hotspot for the dissemination of antibiotic resistance genes (ARGs) and pathogens. This study provides the first comprehensive metagenomic characterization of HWW across Poland, analyzing 64 medical facilities across two seasons via Nanopore long-read sequencing (total of 128 HWW samples). The HWW microbiome was mostly dominated by Proteobacteria, Bacteroidota, and Firmicutes. Multivariate analysis confirmed a significant seasonal shift in the resistome. Winter samples exhibited geographic regionalization, with localized hotspots of specific ARGs, including vancomycin resistance (operon van) and carbapenemase genes (blaOXA, blaNDM). Conversely, summer samples showed a significant trend toward nationwide homogenization, characterized by a uniform distribution of ESBL genes (blaTEM, blaCTX-M) and multidrug resistance (MDR) determinants, alongside the persistence of localized clinical hotspots. Klebsiella pneumoniae emerged as a central network hub, particularly in summer, showing strong correlations with ESBLs. Quantitative genomic co-occurrence analysis revealed a functional division within dominant taxa: while environmental species like Acinetobacter johnsonii comprised the general background microbiome, clinical pathogens such as Acinetobacter baumannii served as primary vectors, showing frequent associations with high-risk ARGs. Environmental and opportunistic bacteria, such as Aeromonas spp. and Citrobacter spp., were identified as putative 'bridge hosts' associated with mobile resistance determinants and potentially contributing to HGT. The findings indicate that seasonal factors, such as increased temperature and sub-inhibitory antibiotic concentrations, may contribute to the transition from regionalized to homogenized resistance profiles, demonstrating that background resistome convergence can coexist with point-source clinical outbreaks. This seasonal "blurring" of regional boundaries positions HWW as an active vector for large-scale antimicrobial resistance (AMR) dissemination. These results underscore the urgent need for nationwide metagenomic surveillance and advanced wastewater treatment strategies within the "One Health" framework to mitigate the environmental spread of WHO priority pathogens.

Acinetobacter baumannii↗

Cu/Zn superoxide dismutase and catalase activities in Pinus mugo needles growing at elevated stands in the mountains, and their photochemical efficiency of PSII.

Pinus mugo needles were sampled at different altitudes (1420, 1590 and 1920 m a.s.l.) to analyse levels of oxidative stress and changes in maximum photochemical efficiency of PSII. Polyacrylamide gel electrophoresis demonstrated that almost all superoxide dismutase activity represented Cu/Zn superoxide dismutase, and only 4-6% represents Mn superoxide dismutase. In extracts from plants sampled at 1590 and 1920 m a.s.l., lower activity of Cu/Zn superoxide dismutase was found. Comparing these data with immunoblots, it can be concluded that the differences in superoxide dismutase activity was related to protein amount. In needles from higher altitudes, a decrease in catalase activity was detected, as opposed to the protein amount, which was higher in needles from the higher stands. Considering the decrease in catalase and Cu/Zn superoxide dismutase activities in needles collected at 1590 and 1920 m a.s.l., we suggest that higher levels of oxidative stress may induce changes in photochemical efficiency of PSII.

Altitude↗

Melanin counter act puromycin-induced inhibition of collagen and DNA biosynthesis in human skin fibroblasts.

Puromycin is an experimental anti-tumor antibiotic acting through inhibition of protein synthesis. Because of its untoward side effects (as inner ear and renal lesions) the antibiotic was not approved for clinical trials. The mechanism underlying the organ specificity of the side effect is not understood. In view of the fact that a number of drugs form with melanin complexes that affect their pharmacological activity, we determined whether puromycin interacts with melanin and how this process affects biosynthesis of collagen in cultured human skin fibroblasts. Our results indicate that puromycin forms complexes with melanin. The amount of puromycin bound to melanin increases with increase of initial drug concentration. The Scatchard plot analysis of the drug binding to melanin has shown that at least two classes of independent binding sites are implicated in the puromycin-melanin complex formation: one class of strong binding sites with the association constant K1 = 1.84 x 10(6) M(-1), and the second class of weak binding sites with the association constant K2 = 5.26 x 10(3) M(-1). The number of total binding sites were n1 = 0.1260 and n2 = 0.2861 mumol puromycin per 1 mg melanin. We found that puromycin induced inhibition of collagen and DNA biosynthesis (IC50 approximately 2 microM). Melanin at 100 microg/ml produced about 20% inhibition of DNA synthesis, but it had no effect on collagen biosynthesis in cultured fibroblasts. However, the addition of melanin (100 microg/ml) to puromycin - treated cells (2 microM) abolished the inhibitory action of puromycin on collagen and DNA biosynthesis. We have suggested that IGF-I receptor expression, involved in collagen metabolism, may be one of the targets for puromycin - induced inhibition of collagen biosynthesis. It was found that melanin abolished puromycin induced decrease in the expression of IGF-I receptor as well MAP kinases expression: ERK1 and ERK2 as shown by Western immunoblot analysis. These data suggest that tissue specific pharmacological activity of puromycin may depend on the melanin abundance in tissues.

Antimetabolites, Antineoplastic↗