The full-length Auxin Response Factor 8 isoform ARF8.1 controls pollen cell wall formation and directly regulates TDF1, AMS and MS188 expression

Auxin Response Factor 8 plays a key role in late stamen development: its splice variants ARF8.4 and ARF8.2 control stamen elongation and anther dehiscence. Here, we characterized the role of ARF8 isoforms in pollen fertility. By phenotypic and ultrastructural analysis of arf8-7 mutant stamens, we found defects in pollen germination and viability caused by alterations in exine structure and pollen coat deposition. Furthermore, tapetum degeneration, a prerequisite for proper pollen wall formation, is delayed in arf8-7 anthers. In agreement, the genes encoding the transcription factors TDF1, AMS, MS188 and MS1, required for exine and pollen coat formation, and tapetum development, are downregulated in arf8-7 stamens. Consistently, the sporopollenin content is decreased, and the expression of sporopollenin synthesis/transport and pollen coat protein biosynthetic genes, regulated by AMS and MS188, is reduced. Inducible expression of the full-length isoform ARF8.1 in arf8-7 inflorescences complements the pollen (and tapetum) phenotype and restores the expression of the above transcription factors. Chromatin immunoprecipitation-quantitative polymerase chain reaction assay revealed that ARF8.1 directly targets the promoters of TDF1, AMS and MS188. In conclusion, the ARF8.1 isoform controls pollen and tapetum development acting directly on the expression of TDF1, AMS and MS188, which belong to the pollen/tapetum genetic pathway.

Higher serum levels of a cathepsin K-generated periostin fragment are associated with fractures in postmenopausal women with primary hyperparathyroidism: a pilot study

The only difference between fractured and non-fractured postmenopausal women with PHPT of same sex, age, and BMI was a significantly mean higher serum k-periostin level. K-periostin value was associated with fracture at any site (odds ratio 1.044, 95% CI 1.005-1.091, p = 0.03).

INTRODUCTION

To assess serum k-periostin fragment levels in patients with primary hyperparathyroidism (PHPT), fractured and non-fractured matched for sex, age, and body mass index.

METHODS

Twenty-five Caucasian fractured postmenopausal women with PHPT (group Fx) and 25 PHPT non-fractured (group NFx) were enrolled. Each patient underwent DXA scan at lumbar, hip, and forearm, spine X-ray, and biochemical evaluation of calcium metabolism. For k-periostin analyses, we utilized a specific ELISA test that detects CatK-generated fragment levels in the bloodstream.

RESULTS

We found no difference in mean BMD and bone turnover marker values between Fx and NFx groups. Prevalence of osteoporosis was not significantly different in Fx vs NFx (72% vs 60%, p = 0.55). Among Fx, 16% reported multiple fractures, 28% morphometric vertebral fractures, 4% femoral fractures, 28% non-vertebral non-femoral fractures, and 8% wrist fractures. The only detectable difference between Fx and NFx group was a significantly mean higher k-periostin serum level (46.2 ± 21.4 vs 34.7 ± 13.5 ng/ml, p = 0.02). K-periostin was associated with fracture at any site (odds ratio 1.044, 95% CI 1.005-1.091, p = 0.03). No difference in mean k-periostin values was found between patients with vertebral fracture vs those with non-vertebral fracture, and between those with multiple fractures vs those with single fracture.

CONCLUSION

Serum k-periostin is significantly associated with fracture in PHPT. If confirmed by further studies, k-periostin could be considered a new marker of bone fragility in PHPT, independently of BMD.

Co-infection of SARS-CoV-2 with Chlamydia or Mycoplasma pneumoniae: a case series and review of the literature

INTRODUCTION

The novel coronavirus SARS-CoV-2 has spread all over the world causing a global pandemic and representing a great medical challenge. Nowadays, there is limited knowledge on the rate of co-infections with other respiratory pathogens, with viral co-infection being the most representative agents. Co-infection with Mycoplasma pneumoniae has been described both in adults and pediatrics whereas only two cases of Chlamydia pneumoniae have been reported in a large US study so far.

METHODS

In the present report, we describe a series of seven patients where co-infection with C. pneumoniae (n = 5) or M. pneumoniae (n = 2) and SARS-CoV-2 was detected in a large teaching hospital in Rome.

RESULTS AND CONCLUSION

An extensive review of the updated literature regarding the co-infection between SARS-CoV-2 and these atypical pathogens is also performed.

Patients' reasons for adhering to long-term alendronate therapy

We aimed to determine patients' reasons for continuing alendronate therapy over 5 years by administering a questionnaire. Bone mineral density, fractures, drugs, Charlson comorbidity index, and lifestyle factors were also considered. Education and awareness of the disease appeared highly associated with good alendronate adherence while worsening health status with discontinuation.

INTRODUCTION

Aim of this study was to investigate patients' reasons for adhering to long-term alendronate therapy (more than 5 years), as data is not available in the current literature regarding the reasons behind long-term adherence.

METHODS

We studied 204 long-term adherent alendronate users: 65 postmenopausal outpatients still adherent (group C, years on treatment = 8.70 ± 1.31) were compared to 139 age-matched patients who discontinued therapy (group S, years on treatment = 8.64 ± 1.43). We evaluated main biochemical parameters, BMD values, fractures, and Charlson comorbidity index (CCI). A questionnaire was administered to analyze the reasons for long-term adherence.

RESULTS

There were no significant differences between groups concerning baseline DXA values, number of fractures, and CCI. A higher education level was observed in group C (C 54% vs S 35% of patients, p = 0.001). At the time of interview, there was a significantly higher number of patients with a CCI of two in group S compared to the beginning of treatment (56% vs 43%, p = 0.04), together with a higher number of patients taking more than 3 drugs (22% vs 11%, p = 0.01) compared to basal evaluation. Forty-seven percent of patients reported new diseases during the treatment as the main reason for stopping alendronate. A multivariate, stepwise logistic regression analysis showed that awareness of the disease was highly associated with adherence (OR = 0.20; 95% CI 0.045-0.93, p = 0.04) followed by higher education (OR = 0.526, 95% CI 0.345-0.801, p = 0.003). Worsening of CCI was associated with discontinuation (OR = 2.75, 95% CI 1.033-7.324, p = 0.04).

CONCLUSIONS

Education and disease awareness are associated with long-term alendronate adherence while competing health problems negatively impact adherence.

A Newly Identified Flower-Specific Splice Variant of AUXIN RESPONSE FACTOR8 Regulates Stamen Elongation and Endothecium Lignification in Arabidopsis

In addition to the full-length transcript ARF8.1, a splice variant (ARF8.2) of the auxin response factor gene ARF8 has been reported. Here, we identified an intron-retaining variant of ARF8.2, ARF8.4, whose translated product is imported into the nucleus and has tissue-specific localization in Arabidopsis thaliana By inducibly expressing each variant in arf8-7 flowers, we show that ARF8.4 fully complements the short-stamen phenotype of the mutant and restores the expression of AUX/IAA19, encoding a key regulator of stamen elongation. By contrast, the expression of ARF8.2 and ARF8.1 had minor or no effects on arf8-7 stamen elongation and AUX/IAA19 expression. Coexpression of ARF8.2 and ARF8.4 in both the wild type and arf8-7 caused premature anther dehiscence: We show that ARF8.2 is responsible for increased expression of the jasmonic acid biosynthetic gene DAD1 and that ARF8.4 is responsible for premature endothecium lignification due to precocious expression of transcription factor gene MYB26 Finally, we show that ARF8.4 binds to specific auxin-related sequences in both the AUX/IAA19 and MYB26 promoters and activates their transcription more efficiently than ARF8.2. Our data suggest that ARF8.4 is a tissue-specific functional splice variant that controls filament elongation and endothecium lignification by directly regulating key genes involved in these processes.

An auxin maximum in the middle layer controls stamen development and pollen maturation in Arabidopsis

Here, we investigated the role of auxin distribution in controlling Arabidopsis thaliana late stamen development. We analysed auxin distribution in anthers by monitoring DR5 activity: at different flower developmental stages; inhibiting auxin transport; in the rpk2-3 and ems1 mutants devoid of middle layer (ML) or tapetum, respectively; and in the auxin biosynthesis yuc6 and perception afb1-3 mutants. We ran a phenotypic, DR5::GUS and gene expression analysis of yuc6rpk2 and afb1rpk2 double mutants, and of 1-N-naphthylphthalamic acid (NPA)-treated flower buds. We show that an auxin maximum, caused by transport from the tapetum, is established in the ML at the inception of late stamen development. rpk2-3 mutant stamens lacking the ML have an altered auxin distribution with excessive accumulation in adjacent tissues, causing non-functional pollen grains, indehiscent anthers and reduced filament length; the expression of genes controlling stamen development is also altered in rpk2-3 as well as in NPA-treated flower buds. By decreasing auxin biosynthesis or perception in the rpk2-3 background, we eliminated these developmental and gene expression anomalies. We propose that the auxin maximum in the ML plays a key role in late stamen development, as it ensures correct and coordinated pollen maturation, anther dehiscence and filament elongation.

Tumour cell population growth inhibition and cell death induction of functionalized 6-aminoquinolone derivatives

OBJECTIVES

A number of previous studies has provided evidence that the well-known anti-bacterial quinolones may have potential as anti-cancer drugs. The aim of this study was to evaluate potential anti-tumour activity and selectivity of a set of 6-aminoquinolones showing some chemical similarity to naphthyridone derivative CX-5461, recently described as innovative anti-cancer agent.

MATERIALS AND METHODS

In-house quinolones 1-8 and ad hoc synthesized derivatives 9-13 were tested on Michigan Cancer Foundation-7 (MCF-7) breast cancer cells and mesenchymal progenitor (MePR2B) cell lines, analysing their effects on the cell cycle and cell death using FACS methodology. Activation of p53 was evaluated by western blotting.

RESULTS

Benzyl esters 4, 5 and their amide counterparts 12, 13 drastically modulated MCF-7 cell cycles inducing DNA fragmentation and cell death, thus proving to be potential anti-tumour compounds. When assayed in non-tumour MePR2B cells, compounds 4 and 5 were cytotoxic while 12 and 13 had a certain degree of selectivity, with compound 12 emerging as the most promising. Western blot analysis revealed that severe p53-K382ac activation was promoted by benzylester 5. In contrast, amide 12 exerted only a moderate effect which was, however, comparable to that of suberoylanilide hydoxamic acid (SAHA).

CONCLUSIONS

Taken together, these results further reinforce evidence that quinolones have potential as anti-cancer agents. Future work will be focused on understanding compound 12 mechanisms of action, and to obtain more potent and selective compounds.

ABCB1 and ABCB19 auxin transporters have synergistic effects on early and late Arabidopsis anther development

Arabidopsis abcb1 abcb19 double mutants defective in the auxin transporters ABCB1/PGP1 and ABCB19/PGP19 are altered in stamen elongation, anther dehiscence and pollen maturation. To assess the contribution of these transporters to stamen development we performed phenotypic, histological analyses, and in situ hybridizations on abcb1 and abcb19 single mutant flowers. We found that pollen maturation and anther dehiscence are precocious in the abcb1 but not in the abcb19 mutant. Accordingly, endothecium lignification is altered only in abcb1 anthers. Both abcb1 and abcb1 abcb19 stamens also show altered early development, with asynchronous anther locules and a multilayer tapetum. DAPI staining showed that the timing of meiosis is asynchronous in abcb1 abcb19 anther locules, while only a small percentage of pollen grains are non-viable according to Alexander's staining. In agreement, TAM (TARDY ASYNCHRONOUS MEIOSIS), as well as BAM2 (BARELY ANY MERISTEM)-involved in tapetal cell development-are overexpressed in abcb1 abcb19 young flower buds. Correspondingly, ABCB1 and ABCB19 mRNA localization supports the observed phenotypes of abcb1 and abcb1 abcb19 mutant anthers. In conclusion, we provide evidence that auxin transport plays a significant role both in early and late stamen development: ABCB1 plays a major role during anther development, while ABCB19 has a synergistic role.

Cadmium-inducible expression of the ABC-type transporter AtABCC3 increases phytochelatin-mediated cadmium tolerance in Arabidopsis

The heavy metal cadmium (Cd) is a widespread environmental contaminant with harmful effects on living cells. In plants, phytochelatin (PC)-dependent Cd detoxification requires that PC-Cd complexes are transported into vacuoles. Here, it is shown that Arabidopsis thaliana seedlings defective in the ABCC transporter AtABCC3 (abcc3) have an increased sensitivity to different Cd concentrations, and that seedlings overexpressing AtABCC3 (AtABCC3ox) have an increased Cd tolerance. The cellular distribution of Cd was analysed in protoplasts from abcc3 mutants and AtABCC3 overexpressors grown in the presence of Cd, by means of the Cd-specific fluorochromes 5-nitrobenzothiazole coumarin (BTC-5N) and Leadmium™ Green AM dye. This analysis revealed that Cd is mostly localized in the cytosol of abcc3 mutant protoplasts whereas there is an increase in vacuolar Cd in protoplasts from AtABCC3ox plants. Overexpression of AtABCC3 in cad1-3 mutant seedlings defective in PC production and in plants treated with l-buthionine sulphoximine (BSO), an inhibitor of PC biosynthesis, had no effect on Cd tolerance, suggesting that AtABCC3 acts via PCs. In addition, overexpression of AtABCC3 in atabcc1 atabcc2 mutant seedlings defective in the Cd transporters AtABCC1 and AtABCC2 complements the Cd sensitivity of double mutants, but not in the presence of BSO. Accordingly, the level of AtABCC3 transcript in wild type seedlings was lower than that of AtABCC1 and AtABCC2 in the absence of Cd but higher after Cd exposure, and even higher in atabcc1 atabcc2 mutants. The results point to AtABCC3 as a transporter of PC-Cd complexes, and suggest that its activity is regulated by Cd and is co-ordinated with the activity of AtABCC1/AtABCC2.

Auxin polar transport in stamen formation and development: how many actors?

In flowering plants, proper development of stamens, the male reproductive organs, is required for successful sexual reproduction. In Arabidopsis thaliana normally six stamen primordia arise in the third whorl of floral organs and subsequently differentiate into stamen filaments and anthers, where male meiosis occurs, thus ending the early developmental phase. This early phase is followed by a late developmental phase, which consists of a rapid elongation of stamen filaments coordinated with anther dehiscence and pollen maturation, and terminates with mature pollen grain release at anthesis. Increasing evidence suggests that auxin transport is necessary for both early and late phases of stamen development. It has been shown that different members of PIN (PIN-FORMED) family are involved in the early phase, whereas members of both PIN and P-glycoproteins of the ABCB (PGP) transporter families are required during the late developmental phase. In this review we provide an overview of the increasing knowledge on auxin transporters involved in Arabidopsis stamen formation and development and we discuss their role and functional conservation across plant species.

Auxin controls Arabidopsis anther dehiscence by regulating endothecium lignification and jasmonic acid biosynthesis

It has been suggested that, in Arabidopsis, auxin controls the timing of anther dehiscence, possibly by preventing premature endothecium lignification. We show here that auxin content in anthers peaks before the beginning of dehiscence and decreases when endothecium lignification occurs. We show that, in the auxin-perception mutants afb1-3 and tir1 afb2 afb3, endothecium lignification and anther dehiscence occur earlier than wild-type, and the gene encoding the transcription factor MYB26, which is required for endothecium lignification, is over-expressed specifically at early stages; in agreement, MYB26 expression is reduced in naphthalene acetic acid-treated anthers, and afb1 myb26 double mutants show no endothecial lignification, suggesting that auxin acts through MYB26. As jasmonic acid (JA) controls anther dehiscence, we analysed how auxin and JA interact. In the JA-defective opr3 mutant, indehiscent anthers show normal timing of endothecium lignification, suggesting that JA does not control this event. We show that expression of the OPR3 and DAD1 JA biosynthetic genes is enhanced in afb1-3 and tir1 afb2 afb3 flower buds, but is reduced in naphthalene acetic acid-treated flower buds, suggesting that auxin negatively regulates JA biosynthesis. The double mutant afb1 opr3 shows premature endothecium lignification, as in afb1-3, and indehiscent anthers due to lack of JA, which is required for stomium opening. By treating afb1 opr3 and opr3 inflorescences with JA, we show that a high JA content and precocious endothecium lignification both contribute to induction of early anther dehiscence. We propose that auxin controls anther dehiscence timing by negatively regulating two key events: endothecium lignification via MYB26, and stomium opening via the control of JA biosynthesis.

Auxin regulates Arabidopsis anther dehiscence, pollen maturation, and filament elongation

We provide evidence on the localization, synthesis, transport, and effects of auxin on the processes occurring late in Arabidopsis thaliana stamen development: anther dehiscence, pollen maturation, and preanthesis filament elongation. Expression of auxin-sensitive reporter constructs suggests that auxin effects begin in anthers between the end of meiosis and the bilocular stage in the somatic tissues involved in the first step of dehiscence as well as in the microspores and in the junction region between anther and filament. In situ hybridizations of the auxin biosynthetic genes YUC2 and YUC6 suggest that auxin is synthesized in anthers. In agreement with the timing of auxin effects, the TIR1, AFB1, AFB2, and AFB3 auxin receptor-encoding genes are transcribed in anthers only during late stages of development starting at the end of meiosis. We found that in tir1 afb triple and quadruple mutants, anther dehiscence and pollen maturation occur earlier than in the wild type, causing the release of mature pollen grains before the completion of filament elongation. We also assessed the contribution of auxin transport to late stamen developmental processes. Our results suggest that auxin synthesized in anthers plays a major role in coordinating anther dehiscence and pollen maturation, while auxin transport contributes to the independent regulation of preanthesis filament elongation.

ROX1, a gene induced by rolB, is involved in procambial cell proliferation and xylem differentiation in tobacco stamen

The Agrobacterium rhizogenes oncogene rolB mimics the effects of auxin in that it increases the sensitivity of transformed cells to this hormone. Here we isolated a tobacco gene, ROX1, acting downstream of rolB. We show that plants with reduced levels of ROX1 mRNA, due to the expression of a 35S-driven ROX1-antisense construct, have flowers with stamens and pistils longer than normal because of an increased number of cells. Localized expression of rolB in anthers results in overexpression of ROX1 and reduced growth of stamens, due to a reduced number of cells. In addition, the longer stamens of antisense plants show a delayed xylem differentiation in the lateral bundles, primarily of the junction region between anther and filament, while the shorter stamens of ROX1-overexpressing plants show a precocious differentiation of xylem cells in the same tissues. Expression of ROX1 in stamens peaks at early stages of stamen growth, and ROX1 mRNA is localized mostly in anther procambial cells. The sequence of ROX1 shares a conserved element with a number of plant genes, including TED3, which is involved in xylem differentiation. These results point to a role of ROX1 in the balance between proliferation of procambial cells and xylem differentiation during stamen development.

6-Aminoquinolones: photostability, cellular distribution and phototoxicity

Three selected aminoquinolones endowed with a potent antibacterial (compounds 1 and 2) and antiviral activity (compound 3) have been evaluated for their phototoxic properties in vitro. Photostability studies of these compounds indicate that compound 3 is photostable whereas compound 1 and in particular, compound 2 are rapidly photodegraded upon UVA irradiation, yielding a toxic photoproduct. Intracellular localization of these compounds has been evaluated by means of fluorescence microscopy using tetramethylrhodamine methyl ester and acridine orange, which are specific fluorescent probes for mitochondria and lysosomes, respectively. No co-staining was observed with lysosomal stain for all the test compounds. On the contrary compound 3 was found to be specifically incorporated in mitochondria. The compounds exhibited remarkable phototoxicity in two cell culture lines: human promyelocytic leukaemia (HL-60) and human fibrosarcoma (HT-1080). The quinolone-induced photodamage was also evaluated measuring the photosensitizing cross-linking in erythrocyte ghost membranes, the strand breaks activity and oxidative damage on plasmid DNA. The results show that these derivatives are able to photoinduce crosslink of erythrocytes spectrin, whereas do not significantly photocleavage DNA directly, but single strand breaks were observed after treatment of photosensitized DNA with two base excision repair enzymes, Fpg and Endo III respectively.

Expression of rolB in tobacco flowers affects the coordinated processes of anther dehiscence and style elongation

The effect of auxin on stamen and pistil development in tobacco flowers was investigated by means of the localized expression of rolB (root loci B), an Agrobacterium oncogene that increases auxin sensitivity in a cell-autonomous fashion. When rolB is driven by the promoter of the meiosis-specific Arabidopsis gene DMC1 (disrupted meiotic cDNA 1), expression occurs earlier in male than in female developing organs, resulting in a delay in anther dehiscence with respect to normal timing of pistil development. As a consequence of this developmental uncoupling, self-pollination is prevented in pDMC1:rolB plants. Histological analysis of pDMC1:GFP plants indicates that in tobacco, this promoter is active not only in meiocytes but also in somatic tissues of the anther. In contrast, simultaneous expression of rolB in anther and pistil somatic tissues, achieved by expressing a construct containing rolB under the control of the promoter of the petunia gene FBP7 (floral binding protein 7), results in a concomitant delay of both anther dehiscence and pistil development without affecting self-pollination of the plants. Analysis of plants harboring the pFBP7:GUS construct shows that in tobacco, this promoter is active not only in the ovules, as described for petunia, but also in pistil and anther somatic tissues involved in the dehiscence program. The delay in anther dehiscence and pistil development could be phenocopied by exogenous application of auxin. Jasmonic acid (JA) could not rescue the delay in anther dehiscence. These results suggest that auxin plays a key role in the timing of anther dehiscence, the dehiscence program is controlled by the somatic tissues of the anther, and auxin also regulates pistil development.

In vitro phototoxic properties of new 6-desfluoro and 6-fluoro-8-methylquinolones

A representative set of potent antibacterial 6-desfluoro-8-methylquinolones, in which the C-6 fluorine atom is replaced by -NH(2) or -H, and their 6-fluoro counterparts, were investigated to evaluate their phototoxic potential and to explore the mechanism behind their phototoxicity. The capacity to photosensitize biological substrates (lipids, proteins, DNA) has been analyzed, as well as their photocytotoxicity on red blood cells and 3T3 murine fibroblasts. The results obtained show that the quinolones studied are able to photosensitize red blood cell lysis in an oxygen-dependent way and induce a high decrease in cell viability after UVA irradiation. A major correlation with phototoxicity lies in the structure of the individual antibacterials and their hydrophobicity; in particular, 6-amino derivatives are less phototoxic than corresponding unsubstituted and fluorinated compounds. Cellular phototoxicity was inhibited by the addition of free radical and hydroxyl radical scavengers (BHA, GSH and DMTU), suggesting the involvement of a radical mechanism in their cytotoxicity. A good correlation was observed between lipid peroxidation and phototoxicity, indicating that the test compounds exert their toxic effects mainly in the cellular membrane. Preliminary experiments on pBR322 DNA show that these derivatives do not photocleave DNA, differently from the two photogenotoxic fluoroquinolones, ciprofloxacin and lomefloxacin, used as reference compounds.

Velnacrine thiaanalogues as potential agents for treating Alzheimer's disease

The only therapeutic drugs for combating dementia disease are acetylcholine esterase inhibitors (AChEI). However, the use of tacrine, the first AChEI to be launched as an Alzheimer's disease (AD) drug, has been limited by serious side effects. Therefore, efforts to search for more potent and selective inhibitors of AChE still remain highly significant in the therapeutic treatment of AD. In this work we modified the cyclohexyl ring of velnacrine, a less toxic analogue of tacrine, by synthesizing a series of thiopyranoquinolines in which the C-3 methylene unit was replaced by a sulphur atom. The anti-AChE data show that the activity was maintained with the bioisosteric substitution carried out. The introduction of a chlorine atom at different positions of the aromatic ring resulted in an array of different activities. In an attempt to understand the different behaviours displayed by the chlorine-substituted derivatives, a molecular docking study was performed.

QSAR study and VolSurf characterization of anti-HIV quinolone library

Antiviral quinolones are promising compounds in the search for new therapeutically effective agents for the treatment of AIDS. To rationalize the SAR for this new interesting class of anti-HIV derivatives, we performed a 3D-QSAR study on a library of 101 6-fluoro and 6-desfluoroquinolones, taken either from the literature or synthesized by us. The chemometric procedure involved a fully semiempirical minimization of the molecular structures by the AMSOL program, which takes into account the solvatation effect, and their 3D characterization by the VolSurf/GRID program. The QSAR analysis, based on PCA and PLS methods, shows the key structural features responsible for the antiviral activity.

6-Aminoquinolones as new potential anti-HIV agents

A series of 6-aminoquinolone compounds were evaluated for their in vitro activity against human immunodeficiency virus type 1 (HIV-1). Compound 12a, bearing a methyl substituent at the N-1 position and a 4-(2-pyridyl)-1-piperazine moiety at the C-7 position, was the most active in inhibiting HIV-1 replication on de novo infected C8166 human lymphoblastoid cell lines. The 12a EC(50) value was 0.1 microM, a 7-20-fold lower concentration relative to that for compounds 8a and 7a containing a cyclopropyl and tert-butyl substituent at the N-1 position, respectively. When the C-6 amino group was replaced with a fluorine atom, a decreased antiviral effect was observed. The observed effects are selective, since potency is substantially reduced when testing the compounds against the herpes simplex virus type 1 (HSV-1). Active quinolone derivatives very efficiently interact with TAR RNA, which suggests a nucleic acid-targeted mechanism of action.

(1,4-Benzothiazinyloxy)alkylpiperazine derivatives as potential antihypertensive agents

A series of compounds having a piperazine moiety variously linked to the benzothiazine nucleus were synthesized and evaluated for their in vitro alpha-adrenoceptor affinity by radioligand receptor binding assays. Some compounds bearing a oxyalkyl-(2-methoxyphenyl)piperazine side chain were good alpha1-adrenoreceptor ligands.

Chemometric rationalization of the structural and physicochemical basis for selective cyclooxygenase-2 inhibition: toward more specific ligands

The discovery that proinflammatory prostaglandins are produced by cyclooxygenase-2 (COX-2), an inducible isoform of the constitutive cyclooxygenase-1 (COX-1), opened a new frontier in the treatment of inflammatory diseases, because the selective inhibition of COX-2 can lead to therapeutically effective compounds which do not have the common side effects of classical non-steroidal antiinflammatory drugs (NSAIDs). Different crystallographic structures of both free COX-1 and COX-2 as well as complexes with inhibitors have been solved. Because of the great similarity between the two enzymes, it is difficult to detect the most important structural and physicochemical features that would be useful for designing inhibitors with an improved selectivity. In this paper we describe the application of a chemometric procedure to the study of COX-2 selective inhibition. This method, developed to reveal the most suitable regions of isoenzymes for the design of selective ligands, also has a very practical utility. GRID multivariate characterization of the enzymes and subsequent Principal Component Analysis (PCA) of the descriptor variables allow the identification of chemical groups that could be added to a core template structure to increase ligand selectivity.

Studies on 6-aminoquinolones: synthesis and antibacterial evaluation of 6-amino-8-ethyl- and 6-amino-8-methoxyquinolones

From our quantitative structure-activity relationship (QSAR) study on a large set of 6-aminoquinolones, which indicated that a group larger than methyl could be allocated at C-8 position, we have synthesized two new series of 6-aminoquinolones characterized by the presence of an ethyl or a methoxy group at C-8 position. The antibacterial evaluation shows that, while the 8-ethyl derivatives were devoid of any antibacterial activity, the introduction of methoxy group gave compounds with good antibacterial activity, especially against gram-positive bacteria. A tentative explanation of the different behaviours among the 8-substituted analogues is given taking into account both the length and electronic properties of the C-8 groups.

Effects of novel 6-desfluoroquinolones and classic quinolones on pentylenetetrazole-induced seizures in mice

There have been several reports that convulsions, although rare, occur in patients who receive fluoroquinolones. In this study, the proconvulsant effects exhibited by a novel series of 6-desfluoroquinolones and some classic quinolones on pentylenetetrazole (PTZ)-induced seizures in mice were evaluated and compared. Animals were intraperitoneally injected with vehicle or quinolone derivatives (5 to 100 microg/g of body weight) 30 min before the subcutaneous (s.c.) administration of PTZ (40 microg/g). In each experiment, mice were then observed for 1 h to monitor for the incidence and onset of clonic seizures. The order of proconvulsant activity in our epileptic model was MF5184 > MF5187 > pefloxacin > MF5189 > ofloxacin > ciprofloxacin > MF5140 > MF5181 > MF5137 > rufloxacin > MF5143 > MF5158 > MF5191 > MF5128 > MF5138 > cinoxacin > MF5142 > norfloxacin > nalidixic acid. The relationship between the chemical structure and the proconvulsant activity of 6-desfluoroquinolone derivatives was studied. We observed that, in terms of toxicity to the central nervous system (CNS), besides the heterocyclic side chain (moiety) at the C-7 position, the C-6 substituent also appears to play an important role. In particular, a hydrogen at the C-6 position seemed to be responsible for major neurotoxic activity in comparison to an amino group located in the same position. The relationship between lipophilicity and proconvulsant activity was also investigated. We did not find any clear relationship between a higher level of lipophilicity and major proconvulsant properties. Although the principal mechanism by which quinolones induce potentiation of the proconvulsant effects of PTZ cannot be easily determined, it is possible that the convulsions are caused by drug interactions, because both PTZ and quinolones are believed to increase excitation of the CNS by inhibition of gamma-aminobutyric acid binding to receptors.

Design and synthesis of modified quinolones as antitumoral acridones

The bacterial topoisomerase II (DNA gyrase) and the mammalian topoisomerase II represent the cellular targets for quinolone antibacterials and a wide variety of anticancer drugs, respectively. In view of the mechanistic similarities and sequence homologies exhibited by the two enzymes, tentative efforts to selectively shift from an antibacterial to an antitumoral activity was made by synthesizing a series of modified tricyclic quinolones, in which the essential 3-carboxylic function is surrogated by phenolic OH and the classic C-6 fluorine atom is replaced by a NH2 group. The resulting 7-amino-9-acridone derivatives were assayed for their antibacterial as well as cytotoxic activities. No antibacterial activity was found. On the other hand, many derivatives showed significant cytotoxic activity against both HL-60 and P388 leukemias and a wide panel of human and rodent solid tumor cells, derivatives 25 and 26 displaying the best overall antiproliferative activity. Against the LoVo cell line, derivative 25 exhibited higher cytotoxic effects than etoposide.

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.

Congenital reflux nephropathy: a follow-up of 108 cases diagnosed perinatally

OBJECTIVE

To determine: (i) the proportion of vesicoureteric reflux (VUR) associated with congenital renal damage and whether it can be severe enough to cause renal impairment from birth: (ii) to evaluate the distribution of males and females affected; and (iii) to describe the course of congenital damage in the first years of life.

PATIENTS AND METHODS

A total of 108 children (76 male and 32 female, M:F 2.3:1), whose VUR was diagnosed before any infection, were followed from birth for a mean (range) of 4.3 (1-10) years. Renal damage was defined by serum creatinine concentration, creatinine clearance and renal imaging (ultrasonography and renal scintigraphy) performed within the first month of life and periodically thereafter.

RESULTS

Of the 108 children, 58 had bilateral and 50 unilateral reflux (total number of refluxing units, 166). High-grade VUR (grade > or = 4) was found in 96 (58%) refluxing renal units (RRUs). Males had a prevalence of bilateral severe (> or = grade 4) reflux (M:F 5.2:1), while in those wit unilateral VUR, the M:F ration was 1.5:1. At birth, mild to moderate damage was present in 56 (36%) RRUs and only associated with VUR of grade > or = 3. Bilateral reflux of grade > or = 4 was associated with congenital moderate/severe renal failure in nine neonates (seven males). In infants with grade > or = 4 VUR who underwent surgical correction, VUR resolved in 92% of cases. In infants with VUR of grade > or = 4 followed medically, the reflux spontaneously resolved in 42% and ameliorated in 16% after 18 months. Serial renal scans during the follow-up showed no progression of renal damage.

CONCLUSIONS

VUR diagnosed at birth on prenatal ultrasonography is associated with congenital damage, with males affected more often than females. The damage involves both kidneys in a consistent proportion and is an important cause of chronic renal impairment from birth. It does not progress in the first years of life if infections are prevented. It is suggested that males with this condition may constitute a major group at risk of developing chronic renal failure in later life.

In vitro activities of new quinolones against Helicobacter pylori

Compounds belonging to a new class of quinolones in which the fundamental C-6 fluorine atom was replaced were evaluated for in vitro antibacterial activity against 32 Helicobacter pylori strains. Since these substitutions resulted in higher inhibitory activities, these new desfluoroquinolones may be useful in eradicating H. pylori infections.

Synthesis and antibacterial evaluation of [1,3]benzothiazino[3,2-a]quinoline- and [3,1]benzothiazino[1,2-a]quinoline-6-carboxylic acid derivatives

A series of [1,3]benzothiazino[3,2-a]quinoline- (5) and [3,1]benzothiazino[1,2-a]quinoline-6-carboxylic acids (10) were synthesized and evaluated for their in vitro antibacterial activity. The activity is discussed in terms of their structural features revealed by molecular orbital correlation.

Chemometric methodologies in a quantitative structure-activity relationship study: the antibacterial activity of 6-aminoquinolones

The paper illustrates the chemometric strategies appropriate for extracting information from a large amount of biological data regarding the antibiotic activity of 6-aminoquinolones. The unique framework based on principal component analysis, projection onto latent structures, and response surface methodologies permits the structure-activity correlations to be shown and to suggest new compounds for further testing. The low activity of the suggested molecules points out the limitations of quantitative structure-activity relationship models when the training set is not properly designed in order to balance all the structural variations taken into account.

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.

Studies on 6-aminoquinolones: synthesis and antibacterial evaluation of 6-amino-8-methylquinolones

The 6-aminoquinolone had previously been identified as a new class of quinolone antibacterial agents. To continue our structure-activity relationship (SAR) study in this series, novel 6-amino-8-methylquinolone derivatives have now been synthesized and evaluated for in vitro antibacterial activity. We have shown that the coupled presence of a methyl group at the C-8 position with an amino group at C-6 is effective for enhancing antibacterial activity, particularly against Gram-positive bacteria. The SARs associated with the N-1, C-6, and C-7 are discussed. The 1,2,3,4-tetrahydroisoquinolinyl derivative 19v showed the highest antibacterial activity with MIC values on Gram-positive bacteria superior to that of ciprofloxacin, especially against Staphylococcus aureus strains, including those strains which are methicillin-and ciprofloxacin-resistant.

6-Aminoquinolones: a new class of quinolone antibacterials?

A series of quinolone- and 1,8-naphthyridone-3-carboxylic acids, designed by previous QSAR studies and characterized by an amino group at the C-6 position instead of the usual fluorine atom, were synthesized for the first time and evaluated for in vitro antibacterial activity. All of the synthesized compounds maintain good activity against Gram-negative bacteria (Pseudomonas aeruginosa excluded), and those compounds having a thiomorpholine group as the C-7 substituent also have good activity against Gram-positive bacteria. Some aspects of structure-activity relationships associated with the C-1, C-5, C-7, and C-8 substituents are also discussed. Derivatives 18g and 38g displayed the best activity with geometric mean MICs of 0.45 and 0.66-0.76 micrograms/mL against Gram-negative and Gram-positive bacteria, respectively. This antimicrobial activity reflects their ability to inhibit bacterial DNA-gyrase. The results of this study show that, while the C-6 fluorine is still the preferred substituent, good activity can still be obtained by replacing it with an amino group.

7-(Disubstituted thiazolyl)-3,5-dihydroxy-6-heptenoic/heptanoic acid derivatives as HMG-CoA reductase inhibitors

A series of disubstituted thiazoles, functionalized with the essential 3,5-dihydroxy-6-heptenoic or heptanoic chain, were prepared and evaluated for their ability to inhibit the enzyme HMG-CoA reductase in vitro. All the synthesized compounds 46-61 showed a moderate inhibitory potency.

Quinolinecarboxylic acids. 3. Synthesis and antibacterial evaluation of 2-substituted-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de] [1,4]benzothiazine-6-carboxylic acids related to rufloxacin

A series of 2-substituted-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzothiazine-6 -carboxylic acids has been prepared and evaluated for in vitro antibacterial activity. These derivatives were less active than corresponding desmethylated analogues. Among these derivatives, the most active compound 22a was selected for preliminary pharmacokinetics in rats. The pharmacokinetic data indicated that 22a was rapidly absorbed and induced lasting plasma and urinary levels. In comparison with rufloxacin, it was excreted in low quantity in urine; a significant amount of desmethylated piperazinyl urinary metabolite was observed.

o-Chlorobenzenesulfonamidic derivatives of (aryloxy)propanolamines as beta-blocking/diuretic agents

A series of compounds 1b-f, 2b-f, and 3b-f having an o-chlorobenzenesulfonamidic diuretic moiety variously linked to the nitrogen side chain of the beta-blocking (aryloxy)propanolamine pharmacophore were prepared and tested for their beta 1-adrenoceptor affinity. For all the active compounds, beta-blocking and diuretic activities were investigated in rats; the structure--activity relationships are discussed. Some of the compounds displayed varying levels of both properties and among these, compounds 1c and 2c have been chosen for further development.

Enantiomers of 8-(3-tert-butylamino-2-hydroxypropoxy)-3,4-dihydro-3-oxo-2H- (1,4)benzothiazine: racemic resolution, chiral synthesis and biological activity

We report the resolution of racemic (+/-)-1 with (R)-(+)-methylbenzyl isocianate and the synthesis of (R)-1 and (S)-1 via Sharpless chiral epoxidation. The enantio- and tissue-selectivity of such enantiomers, as beta- and alpha-adrenoceptor antagonists, were studied. Compound 1, while confirming the potent beta-blocking activity, displayed a modest enantio-selectivity towards beta 1- and beta 2-adrenoceptors. All the compounds displayed no activity as alpha-adrenoceptor blockers.

Synthesis and antiinflammatory/analgesic activities of N-heterocyclic carboxamides of thiopyrano-1,2-benzothiazine

We report the synthesis of N-heterocyclic carboxamides of 5-methyl-4-oxo-2,3,4,5-tetrahydrothiopyrano [3,2-c][1,2]benzothiazine 6,6-dioxide, their antiinflammatory and analgesic activities and the attempts to obtain a corresponding sulfoxidate series. Compounds (II c) and (II l) showed a good antiinflammatory activity which is comparable to that of piroxicam. No compound showed any significant analgesic activity.

[Increase in blood potassium and subsequent normalization: effects on the electrocardiogram. Case report]

Significant variations in the ECG have been observed in a female aged 77 with heart failure and chronic atrial fibrillation during an occasional increase in blood potassium followed by normalization. The major phenomena observed during hyperkalemia, due to a severe dehydration, were a transient sinus rhythm with atrio-ventricular block followed by atrial activity disappearance and advent of interventricular and fascicular block. Therapeutic normalization of blood potassium leads to a progressive disappearance of intraventricular and fascicular block, a temporary sinus rhythm and finally the return to atrial fibrillation which was the steady state of the patient before the blood potassium imbalance.

Quinolonecarboxylic acids. 2. Synthesis and antibacterial evaluation of 7-oxo-2,3-dihydro-7H-pyrido[1,2,3-de][1,4]benzothiazine-6-carboxylic acids

A series of pyridobenzothiazine acid derivatives was synthesized and their in vitro antibacterial activity was evaluated. The 1,4-benzothiazine intermediates, which by Gould-Jacobs quinoline synthesis produced pyridobenzothiazine acids, were prepared by hydrolytic basic cleavage of substituted 2-aminobenzothiazoles and successive cyclocondensation with 1-bromo-2-chloroethane or alternatively with monochloroacetic acid, hence reduction by LiAlH4. The pyridobenzothiazine acids 10c, 30, and 31 show potent antibacterial activities against Gram-positive and Gram-negative pathogens. Structure-activity relationships are discussed. The compound 9-fluoro-10-(4-methyl-1-piperazinyl)-7-oxo-2,3-dihydro-7H-pyrido[1,2,3-d e] [1,4]benzothiazine-6-carboxylic acid (31) (MF-934) has been found to possess, together with the antibacterial activity, a weak acute toxicity and interesting pharmacokinetic characteristics in several animal species (rat, dog, monkey, man).

Synthesis and beta-adrenergic blocking activity of oxipropanolamines of 3,4-dihydro-3-oxo-2H(1,4)benzothiazine

The synthesis of a series of oxypropanolamines of 3,4-dihydro-3-oxo-2H(1,4)benzothiazine is reported. Some of these compounds proved more potent than propranolol and carteolol as beta-adrenergic blocking agents in in vitro tests. The 8-(3-tert-butylamino-2-hydroxy)propoxy-3,4-dihydro-3-oxo-2H(1,4) benzothiazine fumarate (XVI a), which gave better results, confirmed its remarkable activity in in vivo tests.

[Quaternary salts of aminoethyl-p-aminobenzoates and aminoethyl-p-aminobenzamides. Synthesis and pharmacologic activity]

A series of quaternary salts of aminoethyl-p-aminobenzoates and aminoethyl-p-aminobenzamides was synthesized starting from 4-hydroxy-3-carbomethoxy benzoic acid. Pharmacological tests of these compounds show significant spasmolytic activity: in a few cases this was also selective, but at the same time bioavailability was low.