Revisiting the Extended X-ray Absorption Fine Structure Fitting Procedure through a Machine Learning-Based Approach

A novel approach for the analysis of extended X-ray absorption fine structure (EXAFS) spectra is developed exploiting an inverse machine learning-based algorithm. Through this approach, it is possible to explore and account for, in a precise way, the nonlinear geometry dependence of the photoelectron backscattering phases and amplitudes of single and multiple scattering paths. In addition, the determined parameters are directly related to the 3D atomic structure, without the need to use complex parametrization as in the classical fitting approach. The applicability of the approach, its potential and the advantages over the classical fit were demonstrated by fitting the EXAFS data of two molecular systems, namely, the KAu (CN)₂ and the [RuCl₂(CO)₃]₂ complexes.

Photopatterning of fluorescent host-guest carriers through pore activation of metal-organic framework single crystals

Encoded fluorescent particles are fabricated through the selective uptake of dyes in photopatterned metal-organic framework single crystals. The concept is based on spatially controlled photochemical cleavage of pore-blocking pendant groups. Because of the crystalline and porous nature of the host, this approach enables guest uptake that is tunable and can be triggered though controlled irradiation.

Conversion of lactide to acrylic acid by a phosphonium ionic liquid and acid cocatalyst

Combined gas and liquid phase analysis allows closing the mass balance in Bu₄PBr catalyzed production of acrylic acid from lactide.

TRANSPARENT TESTA 16 and 15 act through different mechanisms to control proanthocyanidin accumulation in Arabidopsis testa

Flavonoids are secondary metabolites that fulfil a multitude of functions during the plant life cycle. In Arabidopsis proanthocyanidins (PAs) are flavonoids that specifically accumulate in the innermost integuments of the seed testa (i.e. endothelium), as well as in the chalaza and micropyle areas, and play a vital role in protecting the embryo against various biotic and abiotic stresses. PAs accumulation in the endothelium requires the activity of the MADS box transcription factor TRANSPARENT TESTA (TT) 16 (ARABIDOPSIS B-SISTER/AGAMOUS-LIKE 32) and the UDP-glycosyltransferase TT15 (UGT80B1). Interestingly tt16 and tt15 mutants display a very similar flavonoid profiles and patterns of PA accumulation. By using a combination of genetic, molecular, biochemical, and histochemical methods, we showed that both TT16 and TT15 act upstream the PA biosynthetic pathway, but through two distinct genetic routes. We also demonstrated that the activity of TT16 in regulating cell fate determination and PA accumulation in the endothelium is required in the chalaza prior to the globular stage of embryo development. Finally this study provides new insight showing that TT16 and TT15 functions extend beyond PA biosynthesis in the inner integuments of the Arabidopsis seed coat.

Towards metal-organic framework based field effect chemical sensors: UiO-66-NH2 for nerve agent detection

Kelvin probe monitoring of metal-organic framework coated electrodes is demonstrated as a route for ppb-level detection of alkyl phosphonates.

We present a highly sensitive gas detection approach for the infamous ‘nerve agent’ group of alkyl phosphonate compounds. Signal transduction is achieved by monitoring the work function shift of metal–organic framework UiO-66-NH₂ coated electrodes upon exposure to ppb-level concentrations of a target simulant. Using the Kelvin probe technique, we demonstrate the potential of electrically insulating MOFs for integration in field effect devices such as ChemFETs: a three orders of magnitude improvement over previous work function-based detection of nerve agent simulants. Moreover, the signal is fully reversible both in dry and humid conditions, down to low ppb concentrations. Comprehensive investigation of the interactions that lead towards this high sensitivity points towards a series of confined interactions between the analyte and the pore interior of UiO-66-NH₂.

Access to bacteriophage therapy: discouraging experiences from the human cell and tissue legal framework

Cultures of human epithelial cells (keratinocytes) are used as an additional surgical tool to treat critically burnt patients. Initially, the production environment of keratinocyte grafts was regulated exclusively by national regulations. In 2004, the European Tissues and Cells Directive 2004/23/EC (transposed into Belgian Law) imposed requirements that resulted in increased production costs and no significant increase in quality and/or safety. In 2007, Europe published Regulation (EC) No. 1394/2007 on Advanced Therapy Medicinal Products. Overnight, cultured keratinocytes became (arguably) 'Advanced' Therapy Medicinal Products to be produced as human medicinal products. The practical impact of these amendments was (and still is) considerable. A similar development appears imminent in bacteriophage therapy. Bacteriophages are bacterial viruses that can be used for tackling the problem of bacterial resistance development to antibiotics. Therapeutic natural bacteriophages have been in clinical use for almost 100 years. Regulators today are framing the (re-)introduction of (natural) bacteriophage therapy into 'modern western' medicine as biological medicinal products, also subject to stringent regulatory medicinal products requirements. In this paper, we look back on a century of bacteriophage therapy to make the case that therapeutic natural bacteriophages should not be classified under the medicinal product regulatory frames as they exist today. It is our call to authorities to not repeat the mistake of the past.

Pre-adapting parasitic phages to a pathogen leads to increased pathogen clearance and lowered resistance evolution with Pseudomonas aeruginosa cystic fibrosis bacterial isolates

Recent years have seen renewed interest in phage therapy--the use of viruses to specifically kill disease-causing bacteria--because of the alarming rise in antibiotic resistance. However, a major limitation of phage therapy is the ease at with bacteria can evolve resistance to phages. Here, we determined whether in vitro experimental coevolution can increase the efficiency of phage therapy by limiting the resistance evolution of intermittent and chronic cystic fibrosis Pseudomonas aeruginosa lung isolates to four different phages. We first pre-adapted all phage strains against all bacterial strains and then compared the efficacy of pre-adapted and nonadapted phages against ancestral bacterial strains. We found that evolved phages were more efficient in reducing bacterial densities than ancestral phages. This was primarily because only 50% of bacterial strains were able to evolve resistance to evolved phages, whereas all bacteria were able to evolve some level of resistance to ancestral phages. Although the rate of resistance evolution did not differ between intermittent and chronic isolates, it incurred a relatively higher growth cost for chronic isolates when measured in the absence of phages. This is likely to explain why evolved phages were more effective in reducing the densities of chronic isolates. Our data show that pathogen genotypes respond differently to phage pre-adaptation, and as a result, phage therapies might need to be individually adjusted for different patients.

Effectiveness of bacteriophages in the sputum of cystic fibrosis patients

Bacteriophages have been shown to be effective for treating acute infections of the respiratory tract caused by antibiotic-resistant bacteria in animal models, but no evidence has yet been presented of their activity against pathogens in complex biological samples from chronically infected patients. We assessed the efficacy of a cocktail of ten bacteriophages infecting Pseudomonas aeruginosa following its addition to 58 sputum samples from cystic fibrosis (CF) patients collected at three different hospitals. Ten samples that did not contain P. aeruginosa were not analysed further. In the remaining 48 samples, the addition of bacteriophages led to a significant decrease in the levels of P. aeruginosa strains, as shown by comparison with controls, taking two variables (time and bacteriophages) into account (p = 0.024). In 45.8% of these samples, this decrease was accompanied by an increase in the number of bacteriophages. We also tested each of the ten bacteriophages individually against 20 colonies from each of these 48 samples and detected bacteriophage-susceptible bacteria in 64.6% of the samples. An analysis of the clinical data revealed no correlation between patient age, sex, duration of P. aeruginosa colonization, antibiotic treatment, FEV1 (forced expiratory volume in the first second) and the efficacy of bacteriophages. The demonstration that bacteriophages infect their bacterial hosts in the sputum environment, regardless of the clinical characteristics of the patients, represents a major step towards the development of bacteriophage therapy to treat chronic lung infections.

Base catalytic activity of alkaline earth MOFs: a (micro)spectroscopic study of active site formation by the controlled transformation of structural anions

The selective decomposition of structural nitrate anions in alkaline earth MOFs generates highly dispersed base sites with catalytic applications.

Dynamic changes in parameters of redox balance after mild heat stress in aged laying hens (Gallus gallus domesticus)

In order to evaluate the metabolic responses of laying hens induced by high temperature at later laying stage, nine 60-wk-old laying hens (Gallus gallus domesticus) were employed in the present study. The hens were exposed to 32 degrees C for 21 d and blood samples were obtained before and at 1, 7, 14 and 21 d of heat exposure. The reactive oxygen species (ROS) formed in blood during heat exposure were estimated by the ex vivo spin-trapping method. Body temperature and plasma concentrations of glucose, urate, creatine kinase (CK), triiodothyronine (T(3)), thyroxine (T(4)), corticosterone (CORT), thiobarbituric acid reacting substances (TBARS), ferric/reducing antioxidant power (FRAP) and superoxide dismutase (SOD) activity were measured. Plasma levels of glucose, CK and CORT were not significantly influenced by heat exposure at any time point. The circulating concentrations of T(3) were decreased while plasma T(4) levels changed in the opposite way. The formation of ROS was significantly augmented by heat exposure in laying hens though the body temperature was not significantly altered. The enhanced enzymatic and non-enzymatic antioxidant systems acted in concert to alleviate the heat stress evoked oxidative damage.

Oligosaccharide Binding in Family 8 Glycosidases: Crystal Structures of Active-Site Mutants of the β-1,4-Xylanase pXyl from Pseudoaltermonas haloplanktis TAH3a in Complex with Substrate and Product,

The structures of inactive mutants D144A and E78Q of the glycoside hydrolase family 8 (GH-8) endo-beta-1,4-d-xylanase (pXyl) from the Antarctic bacterium Pseudoalteromonas haloplanktis TAH3a in complex with its substrate xylopentaose (at 1.95 A resolution) and product xylotriose (at 1.9 A resolution) have been determined by X-ray crystallography. A detailed comparative analysis of these with the apo-enzyme and with other GH-8 structures indicates an induced fit mechanism upon ligand binding whereby a number of conformational changes and, in particular, a repositioning of the proton donor into a more catalytically competent position occurs. This has also allowed for the description of protein-ligand interactions in this enzyme and for the demarcation of subsites -3 to +3. An in-depth analysis of each of these subsites gives an insight into the structure-function relationship of this enzyme and the basis of xylose/glucose discrimination in family 8 glycoside hydrolases. Furthermore, the structure of the -1/+1 subsite spanning complex reveals that the substrate is distorted from its ground state conformation. Indeed, structural analysis and in silico docking studies indicate that substrate hydrolysis in GH-8 members is preceded by a conformational change, away from the substrate ground-state chair conformation, to a pretransition state local minimum (2)S(O) conformation.

Study of the Active Site Residues of a Glycoside Hydrolase Family 8 Xylanase

Site-directed mutagenesis and a comparative characterisation of the kinetic parameters, pH dependency of activity and thermal stability of mutant and wild-type enzymes have been used in association with crystallographic analysis to delineate the functions of several active site residues in a novel glycoside hydrolase family 8 xylanase. Each of the residues investigated plays an essential role in this enzyme: E78 as the general acid, D281 as the general base and in orientating the nucleophilic water molecule, Y203 in maintaining the position of the nucleophilic water molecule and in structural integrity and D144 in sugar ring distortion and transition state stabilization. Interestingly, although crystal structure analyses and the pH-activity profiles clearly identify the functions of E78 and D281, substitution of these residues with their amide derivatives results in only a 250-fold and 700-fold reduction in their apparent k(cat) values, respectively. This, in addition to the observation that the proposed general base is not conserved in all glycoside hydrolase family 8 enzymes, indicates that the mechanistic architecture in this family of inverting enzymes is more complex than is conventionally believed and points to a diversity in the identity of the mechanistically important residues as well as in the arrangement of the intricate microenvironment of the active site among members of this family.

Impact of Pd-mordenite pretreatment on the heterogeneity of Heck catalysis

In Heck reactions with tributylamine as the base and in toluene, Pd(NH3)4(2+)-mordenite (0.4 wt% Pd) and Pd0-mordenite (0.4 and 4 wt% Pd) are not only active and selective, but also truly heterogeneous catalysts, while oxidized PdII species in an all-oxygen environment, i.e. ionic Pd2+ or PdO, are prone to leaching.

In vitro study of the photocytotoxicity of some hypericin analogs on different cell lines

In the present study, hypericin analogs with an increased hydrophilic character were synthesized. As chemical modifications alter the lipophilicity/hydrophilicity balance together with the photophysical/chemical background of the molecule the influence of these structural changes on the cellular uptake, retention and subcellular localization in HeLa cells was investigated. Besides, their photocytotoxic effects using three cell lines (HeLa, MCF-7, A431), as well as their plasma protein binding were also assessed. To assess the relative hydrophilic/lipophilic character of hypericin and analogs their retention times were determined on a reversed phase high performance liquid chromatography (C-18) column. The retention time of all the hypericin analogs was < 46 min, except for dibenzyltetramethylhypericin (118 min), while the retention time of hypericin was > 200 min (solvent system: methanol/citrate buffer 30 mM pH 7; 70/30). Hypericin, hexa-, penta- and dibenzyltetramethylhypericin displayed a potent antiproliferative effect at the nanomolar range after photosensitization (3.6 J/cm2). On the contrary, photoactivated tetrasulfonhypericin and fringelite D had no antiproliferative effect on the three cell lines, whereas hypericin polyethylene glycol showed only an intermediate cytotoxic effect on A431 cells. In dark conditions no antiproliferative effect was observed for any photosensitizer. The antiproliferative photo-effect correlated well with the intracellular accumulation as measured using HeLa cells. In general, the photocytotoxic hypericin analogs concentrated to a large extent, while the noncytotoxic compounds were not taken up by the HeLa cells. Furthermore, confocal laser microscopy revealed that all photosensitizers mainly concentrated in the perinuclear region, probably corresponding with Golgi apparatus and the endoplasmic reticulum, except for tetrasulfonhypericin which located at the plasma membrane. In addition, the plasma protein binding studies illustrated that hypericin bind extensively to the low-density lipoproteins, while the other hypericin analogs were mainly bound to heavy proteins (mostly albumin) and to a small extent to low-density lipoproteins.

Simple ion chromatographic method for the determination of chlormequat residues in pears

Current methods for quantitative determination of chlormequat residues in food crops are characterized by rather low recoveries and the need for derivatization (in case of gas chromatography, GC), or by high capital investment (in case of liquid chromatography-mass spectrometry, LC-MS). We propose a cation-exchange chromatography method for the analysis of chlormequat in pears. The method is based on extraction of the target compound with 40 mM HCl, followed by centrifugation and filtration. The filtrate is directly injected into an ion chromatograph equipped with a commercially available cation-exchange column and a suppressed conductivity detection system. While the limit of detection (LOD) (0.5 mg/kg) may not be small enough to allow dietary analysis, the method meets all validation requirements and is an alternative for the existing GC and LC-MS methods in quality control.

Study of pyoverdine type and production by Pseudomonas aeruginosa isolated from cystic fibrosis patients: prevalence of type II pyoverdine isolates and accumulation of pyoverdine-negative mutations

The lungs of cystic fibrosis patients are frequently colonized by Pseudomonas aeruginosa, which produces high-affinity fluorescent peptidic siderophores, pyoverdines. Three pyoverdines which differ in their peptide chain and are easily differentiated by isoelectric focusing exist, only one being produced by a given strain. P. aeruginosa isolates from cystic fibrosis patients of a German hospital were analyzed by sequential, pulse-field gel electrophoresis (PFGE) and for pyoverdine production and type. Only producers of type I and type II pyoverdine were found. There was a perfect correlation between the type of pyoverdine produced and the clonality determined by PFGE. PFGE clone C, the most prevalent among cystic fibrosis patients, and found in an aquatic environment, produced type II pyoverdine. Pyoverdine-negative mutants seemed to increase as a function of the lung colonization time, but retained the capacity to take up pyoverdines. Most isolates that took up type II pyoverdine were also able to utilize type I pyoverdine as judged by growth stimulation experiments. No correlation was observed between the loss of pyoverdine production and mucoidy.

A comparative study of the photosensitizing characteristics of some cyanine dyes

The present work has been carried out to explore the potential application of cyanines in photodynamic therapy. After photosensitization, the in vitro cytotoxic and antiproliferative activity on HeLa cells of a total of 35 cyanines belonging to several chemical subgroups is explored. Most of these cyanines have never been used before in similar experimental work. From a first set of experiments, it is found that none of the krypto-, oxa- and imidacyanines is photobiologically active on HeLa cells. Conversely, five thiacyanines (Thiacl-5), one rhodacyanine (Rhodac) and four indocyanines (Indoc2, Indoc4, Indoc5, Indoc7) show photodependent cytotoxicity or antiproliferative effects. A more detailed study shows that out of the ten selected compounds, eight cyanines feature significant photodependent cytotoxic and antiproliferative effects. All possess maximum absorption ranges between 545 and 824 nm. In particular, Rhodac, a tetramethinemeromonomethine rhodacyanine dye with an absorption maximum of 655 nm (ethanol) and a molar absorption coefficient epsilon = 108000 shows very promising photo-dependent biological activity. In general, the measured singlet oxygen quantum yield of the selected cyanines is low (< 0.08) and does not correlate with the degree of photosensitization. Furthermore, the present study shows that cyanines with a partition coefficient close to 1.5 accumulate to the highest extent in HeLa cells, while the more hydrophobic compounds (e.g., indocyanines) concentrate less intracellularly.

Quantitation of Pseudomonas aeruginosa in wound biopsy samples: from bacterial culture to rapid 'real-time' polymerase chain reaction

STATEMENT OF FINDINGS: We developed a real-time detection (RTD) polymerase chain reaction (PCR) with rapid thermal cycling to detect and quantify Pseudomonas aeruginosa in wound biopsy samples. This method produced a linear quantitative detection range of 7 logs, with a lower detection limit of 103 colony-forming units (CFU)/g tissue or a few copies per reaction. The time from sample collection to result was less than 1h. RTD-PCR has potential for rapid quantitative detection of pathogens in critical care patients, enabling early and individualized treatment.

Sequence diversity of the oprI gene, coding for major outer membrane lipoprotein I, among rRNA group I pseudomonads

The sequence of oprI, the gene coding for the major outer membrane lipoprotein I, was determined by PCR sequencing for representatives of 17 species of rRNA group I pseudomonads, with a special emphasis on Pseudomonas aeruginosa and Pseudomonas fluorescens. Within the P. aeruginosa species, oprI sequences for 25 independent isolates were found to be identical, except for one silent substitution at position 96. The oprI sequences diverged more for the other rRNA group I pseudomonads (85 to 91% similarity with P. aeruginosa oprI). An accumulation of silent and also (but to a much lesser extent) nonsilent substitutions in the different sequences was found. A clustering according to the respective presence and/or positions of the HaeIII, PvuII, and SphI sites could also be obtained. A sequence cluster analysis showed a rather widespread distribution of P. fluorescens isolates. All other rRNA group I pseudomonads clustered in a manner that was in agreement with other studies, showing that the oprI gene can be useful as a complementary phylogenetic marker for classification of rRNA group I pseudomonads.

Analysis of epidemic Pseudomonas aeruginosa isolates by isoelectric focusing of pyoverdine and RAPD-PCR: modern tools for an integrated anti-nosocomial infection strategy in burn wound centres

The Gram-negative bacterium Pseudomonas aeruginosa is an important life-threatening nosocomial pathogen in burn units. In this study we analysed epidemic P. aeruginosa isolates from patients and their hospital environment using two new molecular techniques in order to establish strain relatedness for epidemiological purposes. One technique was pyoverdine typing by isoelectric focusing (PVD-IEF) and the other was a genomic PCR-based fingerprinting technique called random amplification of polymorphic DNA actually referred to as RAPD-PCR. The described short epidemic (6 weeks) included 37 consecutive isolates from 9 different patients as well as two environmental isolates recovered, at the same time, from one of the hydrotherapy facilities. Only two of the three known pyoverdine types of P. aeruginosa could be found. Type I was absent while type II represented 49 per cent and type III, 51 per cent of the isolates. The two consecutive isolates from the environment were both of type III. The RAPD-PCR fingerprinting discriminated four patterns. Profile 1 represented 60 per cent; profile 2, 34 per cent; and profiles 3 and 4 only 3 per cent of the isolates respectively. The environmental isolates also had a RAPD-PCR 1 profile, arguing for the hydrotherapy facility as a possible contamination source. Prompt measures could prevent an outbreak. The study demonstrates the applicability of the techniques in a routine microbiology lab as well as their usefulness, in combination with other techniques, in the fight against nosocomial infections, which are so critical in burn units. Both techniques showed undoubtable evidence of the occurrence of polymicrobial infection of individual patients by P. aeruginosa species. Meanwhile pyoverdine typing by IEF seems suited to studying more profoundly the role of pyoverdines in burns.

Direct detection and identification of Pseudomonas aeruginosa in clinical samples such as skin biopsy specimens and expectorations by multiplex PCR based on two outer membrane lipoprotein genes, oprI and oprL

A multiplex PCR test based on the simultaneous amplification of two lipoprotein genes, oprI and oprL, was designed and evaluated for its ability to directly detect fluorescent pseudomonads (amplification of oprI open reading frame, 249 bp) and Pseudomonas aeruginosa (amplification of oprL open reading frame, 504 bp) in clinical material. A collection of reference strains including 20 different species of fluorescent pseudomonads was tested. Positive PCR results for both genes were observed only for P. aeruginosa isolates (n = 150), including strains of clinical and environmental origin, while only one gene, oprI, was amplified from the other fluorescent pseudomonads. All other bacteria tested (n = 15) were negative by the amplification test. The lower detection level for P. aeruginosa was estimated to be 10(2) cells/ml. Preliminary evaluation on testing skin biopsy specimens from patients with burns (n = 14) and sputum samples from cystic fibrosis patients (n = 49) and other patients (n = 19) showed 100% sensitivity and 74% specificity in comparison with culture. This multiplex PCR assay appears promising for the rapid and sensitive detection of P. aeruginosa in clinical specimens. Further evaluation of its specificity in longitudinal clinical studies is warranted.

Antitumour activity and retinotoxicity of ethyldeshydroxy-sparsomycin in mice

The colony formation in agar of human tumour xenografts was used as a test system to study the cytostatic activity of ethyldeshydroxy-sparsomycin (EdSm) at the cellular level. EdSm was additionally studied in vivo in human tumour xenografts and murine tumour models. EdSm showed a clear dose-response effect in vitro. At continuous exposure with 0.01 micrograms/ml, 2 out of 11 of the tumours responded (a gastric and a small cell lung carcinoma). At 0.1 mu/ml EdSm, the tumour response was 5/11 tumours and at 1 microgram/ml the compound was active in all tumours. The maximal tolerable doses of EdSm in vivo have been determined in non-tumour bearing CDF1 mice. In the intraperitoneally (i.p.) given multiple dose schedules the respective LD10 doses indicated that the tolerable cumulative dose increases when lower doses are given more frequently. This also enhances the antitumour activity in L1210 leukaemia to 172% T/C. On the other hand, continuous infusion strongly diminished the tolerable dose as well as the antitumour activity. EdSm was also active against i.p. inoculated P388 leukaemia (150% T/C), B16 melanoma (156% T/C), and RC carcinoma (197% T/C), and the subcutaneously (s.c.) inoculated L1210 (139% T/C) and RC (138% T/C). Absence of tumour responses was found in the following s.c. implanted murine tumours: M5076 sarcoma, osteosarcomas C22LR and CP369, and the LL carcinoma, as well as in the human tumour xenografts: LXFG 529, a non-small cell lung carcinoma; GXF 251, a gastric carcinoma; and FMa, an ovary carcinoma. Possible long-range retinotoxic effects of EdSm were investigated in tumour-bearing mice, cured after surviving treatment with LD50 doses of EdSm, by assaying the protein biosynthetic capacity of the retinal by assaying the ocular rhodopsin and opsin levels as parameters. In none of these cases could a significant reduction in either opsin or rhodopsin levels be measured and no changes were seen histologically.

Preclinical antitumor activity of ethyldeshydroxysparsomycin in combination with cisplatin

The efficacy of cisplatin (CDDP) in combination with the protein synthesis inhibitor ethyldeshydroxysparsomycin (EDSM) has been tested in two tumor models at various schedules. Mice with L1210 leukemia or B16 melanoma were treated with CDDP alone or in combination with EDSM. Against L1210 leukemia, which is sensitive to CDDP, combinations elicited increases in life-span for all treatment schedules compared to those achieved with the corresponding dose of CDDP. Moreover, the combination of EDSM with this platinum compound yielded a cure rate > 80%, compared to < 35% for single CDDP treatment. Although the B16 melanoma is rather resistant to both CDDP and EDSM, combinations of these agents against B16 melanoma showed schedule dependent efficacy and in certain schedules significant therapeutic advantage over individual drug treatment, but cures were not observed. Our results suggest that EDSM has significant synergistic capabilities in both animal tumor models, but strong therapeutic enhancement of cisplatin efficacy is only seen when the tumor is sensitive to CDDP.

In vitro antiproliferative effects, toxicity profiles in vivo in mice and antitumour activity in tumour-bearing mice of five organotin compounds

The in vitro antiproliferative effects, the toxicity profiles in vivo in mice and the antitumour activity in tumour-bearing mice were screened for five recently synthesized organotin compounds: triphenyltin 5-sulfosalicylate (1), triphenyltin 5-aminosalicylate (2), triphenyltin 4-fluorobenzoate (3), tri-n-butyltin 2,6-difluorobenzoate (4) and di-n-butyltin bis (2,5-dihydroxybenzoate) (5). The in vitro chemosensitivity tests showed that compound 1 has the lowest antiproliferative effect in C26-10. In WiDr, compounds 1 and 5 were less active than the other compounds tested. The IC50 for cisplatin in C26-10 was in the same range as for 1. For compound 3 a steep dose response curve in C26-10 turned out to be remarkably different from the curves of the other compounds. In vivo, compound 1 was most toxic, mainly through paralysis. At their maximum tolerated dose (MTD) for single administration compounds 1, 2, 3 and 4 are inactive against murine colon carcinoma Colon 26. At a single administration, compound 5 was the most active compound with Test/Control ratio (T/C) below 0.6 and Growth Delay Factor (GDF) above 1.0, their respective cut-off levels for sensitivity.

Detection of the outer membrane lipoprotein I and its gene in fluorescent and non-fluorescent pseudomonads: implications for taxonomy and diagnosis

The open reading frame of the OprI lipoprotein gene from Pseudomonas aeruginosa was amplified by polymerase chain reaction (PCR) starting from purified DNA or colony lysates. A fragment of the expected size (249 bp) was detected in all P. aeruginosa strains from various clinical and geographical origins. The gene could only be amplified in pseudomonads of rRNA group I which are considered to be the authentic genus Pseudomonas. Digestions with HaeIII, PvuII and SphI of the amplified fragments demonstrated a sequence variation in the oprI gene. Colony, dot and Western blots with two monoclonal antibodies (mAbs) against the lipoprotein I confirmed our PCR results. These findings open interesting perspectives for the molecular taxonomy of the genus Pseudomonas and the development of diagnostic tools.

Parameters affecting the degradation of benzothiazoles and benzimidazoles in activated sludge systems

It was found that benzothiazole, 2-oxybenzothiazole and 2-benzothiazolesulphonate were degraded in activated sludge systems. 2-Mercaptobenzothiazole (MBT) was more resistant, although the first step in MBT degradation seemed to be transformation to the sulphonate form. At higher MBT concentrations, it was transformed into a disulphide, which accumulated in the sludge. MBT was also found to be mainly responsible for the toxicity of rubber chemical waste-water towards activated sludges. It inhibited the degradation of the other heterocycles. Only at concentrations of around 20 ppm was MBT degraded. Mercaptobenzimidazole ranked second in resistance to degradation.

Oral health status and treatment needs of black college students at Khayelitsha

Descriptive information on the oral health status and treatment needs of black students at a teacher training college in Khayelitsha was collected to facilitate the planning of appropriate preventive and therapeutic programmes. A random sample of 96 subjects was drawn from the college population. The average age of the group was 27.3 years; 83.3 per cent were females and 90.6 per cent had experienced caries. The mean DMFT was high (11.14), the mean score for males was almost half that for females (p = 0.0247). 54.2 per cent needed treatment for caries such as fillings (47.9 per cent) and extractions (25.0 per cent). No students had shallow pocketing and deep pockets were recorded in only 3.4 per cent. However more than 4 segments on average showed signs of bleeding or higher scores for periodontal disease. A significant difference existed between the sexes for the presence of calculus (p less than 0.005). Oral hygiene instruction and prophylaxis were needed by the majority of students namely 92.1 per cent and 70.8 per cent respectively. The high number of students with bleeding and calculus indicates that an intensive program of oral health education is required by this group.

Cytotoxic activity of di-n-butyltin(IV)(X-A-B-Y) compounds related to salicylic acid against human tumour cells

A series of di-n-butyltin(IV) compounds of the type di-n-butyltin(IV)(X-A-B-Y) with the (X-A-B-Y) being related to salicylic acid was tested in vitro for cytotoxic activity against tumour cells of the human A 204, MCF-7, T24, WiDr and IgR-37 cell lines using the PIT method. In each cell line the di-n-butyltin(IV) compounds displayed similar activity. As compared to cisplatin, the compounds were 4- to 10-fold more effective against A 204, MCF-7 and T24 tumour cells and slightly more effective against WiDr cells. The effectiveness against IgR-37 cells was similar for cisplatin and di-n-butyltin (IV) compounds.

The bioavailability of Tamoplex (tamoxifen). Part 3. A steady-state study in breast cancer patients

The bioavailability of two tamoxifen preparations (Tamoplex and Nolvadex) was compared in a multiple dose two-way cross-over design in twelve breast cancer patients. The formulations were found to be bioequivalent. Mean steady-state serum levels of tamoxifen and N-desmethyltamoxifen were 133 ng/ml and 242 ng/ml, respectively, at a single daily dose of three tablets of Tamoplex 10 mg and 128 ng/ml and 248 ng/ml, respectively, at a single daily dose of three tablets of Nolvadex 10 mg. While there was a large interpatient as well as intrapatient variability in steady-state levels of tamoxifen and N-desmethyltamoxifen, their ratio appeared to be constant in the individual patient.

The bioavailability of two new preparations of spironolactone tablets

Two new preparations of spironolactone tablets containing 25 and 100 mg of spironolactone have been characterized by their disintegration time, tablet spironolactone content, dissolution profile and bioavailability in comparison with two known spironolactone preparations as reference material. The preparations were found to possess almost identical characteristics, assuring a proper clinical use of the new tablet preparations. For spironolactone, a positive outcome of the in vitro dissolution test coincides with an excellent bioavailability.

Bioavailability of methotrexate tablets

The bioavailability of methotrexate 10 mg tablets has been determined to be 62 +/- 16%. After administration of a dose of 30 mg/m2 a maximum plasma concentration of ca. 20.10(-7) mole/l was found after ca. 1.7 h. The methotrexate plasma half-life was 2.4 h. It was concluded that the 10 mg tablet formulation at the dosage investigated is a suitable clinical methotrexate preparation.