Synthesis and biological activity of 4″-O-acyl derivatives of 14- and 15-membered macrolides linked to ω-quinolone-carboxylic unit

The synthesis and antimicrobial activity of a new class of macrolide antibiotics which consist of a macrolide scaffold and a quinolone unit covalently connected by an appropriate linker are described. Optimization of several synthetic steps and structural properties of lead compound 26 are discussed. Promising antibacterial properties of this compound and some of its analogues are reported.     

Nutritional risk screening in hospitalized and haemodialysis patients

Malnutrition is an independent risk factor impacting on higher complications and increased length of hospital stay and costs. The aim of this study was to determine the prevalence of nutritional risk among patients on regular haemodialysis (HD) (Group I, N = 105) and among the patients at Gastroenterology, Endocrinology, Hematology and Clinical Immunology (Group II, N = 652). Cross-sectional nutritional evaluation was done using Nottingham Hospital Screening Tool (NS). The prevalence of nutritional risk was 9% in Group I and 21% in Group II (p = 0.0002). We found statistically significant larger quantity of malnourished patients among acute internistic patients than among chronic from the same Group II. Malnutrition among patients on HD didn't differ statistically to chronic internistic patients. We didn't found a significantly higher percentage of nutritional risk among elderly patients (65 years and more). Correlation between body mass index (BMI) and NS was significant, but weak (r = -0.32). We can conclude that the prevalence of nutritional risk among HD patients was lower than we had expected. It seems that the screening tool we used is not sensitive enough for HD patients and needs further investigations.     

Soft-start polymerization of fissure sealant: retention after three years

The aim of this study was to investigate retention of composite fissure sealant polymerized with standard and soft-start technique after a three year clinical trial. One hundred teeth were divided into two groups (A&B) of teeth and sealed with composite material (Visioseal, 3M Espe) using split mouth design. Sealants were polymerized using standard (Group A) and soft-start (Group B) techniques with commercial polymerization unit (Elipar Highlight, 3M Espe). Retention rate in Group A was 72%. In 14 teeth sealant was partially or completely missing. Group B showed retention rate of 80%. Sealant was partially or completely missing in 10 teeth. Six new caries lesions in Group A (3) and B (3) were detected. Mann-Whitney test did not reveal significant differences between the polymerization techniques. After three years complete retention of sealants, regardless of the group, was 76% (76 teeth) with six new caries lesions. Soft-start polymerization showed a comparable retention rate as the standard polymerization technique.     

Assessment of cortical bone fracture resistance curves by fusing artificial neural networks and linear regression

Bone injures (BI) represents one of the major health problems, together with cancer and cardiovascular diseases. Assessment of the risks associated with BI is nontrivial since fragility of human cortical bone is varying with age. Due to restrictions for performing experiments on humans, only a limited number of fracture resistance curves (R-curves) for particular ages have been reported in the literature. This study proposes a novel decision support system for the assessment of bone fracture resistance by fusing various artificial intelligence algorithms. The aim was to estimate the R-curve slope, toughness threshold and stress intensity factor using the two input parameters commonly available during a routine clinical examination: patients age and crack length. Using the data from the literature, the evolutionary assembled Artificial Neural Network was developed and used for the derivation of Linear regression (LR) models of R-curves for arbitrary age. Finally, by using the patient (age)-specific LR models and diagnosed crack size one could estimate the risk of bone fracture under given physiological conditions. Compared to the literature, we demonstrated improved performances for estimating nonlinear changes of R-curve slope (R² = 0.82 vs. R² = 0.76) and Toughness threshold with ageing (R² = 0.73 vs. R² = 0.66).     

Subcomponent Vaccine Based on CTA1-DD Adjuvant with Incorporated UreB Class II Peptides Stimulates Protective Helicobacter pylori Immunity

A mucosal vaccine against Helicobacter pylori infection could help prevent gastric cancers and peptic ulcers. While previous attempts to develop such a vaccine have largely failed because of the requirement for safe and effective adjuvants or large amounts of well defined antigens, we have taken a unique approach to combining our strong mucosal CTA1-DD adjuvant with selected peptides from urease B (UreB). The protective efficacy of the selected peptides together with cholera toxin (CT) was first confirmed. However, CT is a strong adjuvant that unfortunately is precluded from clinical use because of its toxicity. To circumvent this problem we have developed a derivative of CT, the CTA1-DD adjuvant, that has been found safe in non-human primates and equally effective compared to CT when used intranasally. We genetically fused the selected peptides into the CTA1-DD plasmid and found after intranasal immunizations of Balb/c mice using purified CTA1-DD with 3 copies of an H. pylori urease T cell epitope (CTA1-UreB3T-DD) that significant protection was stimulated against a live challenge infection. Protection was, however, weaker than with the gold standard, bacterial lysate+CT, but considering that we only used a single epitope in nanomolar amounts the results convey optimism. Protection was associated with enhanced Th1 and Th17 immunity, but immunizations in IL-17A-deficient mice revealed that IL-17 may not be essential for protection. Taken together, we have provided evidence for the rational design of an effective mucosal subcomponent vaccine against H. pylori infection based on well selected protective epitopes from relevant antigens incorporated into the CTA1-DD adjuvant platform.     

Synthesis and characterisation of dinuclear oxomolybdenum(V) complexes with thienyl carboxylate ligands

The first structurally characterised oxomolybdenum(V) complexes with thienyl carboxylate ligands were prepared by the reaction of [Mo₂O₃(C₅H₇O₂)₄] or (NH₄)₂[MoOCl₅] with the corresponding acid (2-thiophenecarboxylic, 5-methyl-2-thiophenecarboxylic or 3-(3-thienyl)acrylic acid). Complexes [Mo₂O₃(μ-OC₂H₅)(μ-O₂CR)(C₅H₇O₂)₂](R = -C₄H₃S (1), -C₄H₂S(CH₃) (2) or -CHCHC₄H₃S (3)) were obtained upon substitution of two acetylacetonate ligands from [Mo₂O₃(C₅H₇O₂)₄] with RCOO⁻ in dry ethanol. Reactions of (NH₄)₂[MoOCl₅] with the corresponding thienyl carboxylic acid in the presence of γ-picoline (C₆H₇N) yielded complexes (C₆H₇NH)[Mo₂O₄(μ-O₂CR)Cl₂(C₆H₇N)₂] (R = -C₄H₃S (4), -C₄H₂S(CH₃) (5) or -CHCHC₄H₃S (6)). All of the six new complexes were characterised as dinuclear. The molecular structures of 1, 3, 4·0.5CH₃CN and 5 were determined by the single crystal X-ray diffraction method. In the complexes the two molybdenum atoms are doubly bridged either by one oxygen and one ethoxy-oxygen, or alternatively by two oxo-oxygens, and are additionally bridged by the thienyl carboxylate ion in a didentate bridging manner. All complexes were further characterised by means of chemical analysis, IR spectroscopy, TG and in some cases by the one and two-dimensional NMR method.     

Mushroom poisoning

In the research we included a total of 207 subjects with the dismissal diagnosis of "mycetismus", who were treated at the Department of Infectious Diseases, General Hospital Osijek, during the 1983-1992 period. 32 of them were children. There were 44.93% of men, 39.61% of women and 15.45% of children. The latent time > 6 hours was determined in 51 (25%) and < 6 hours in 75% of subjects. In 156 of patients with the latent time > 6 hours, "false" poisoning occured, while 51 patients experienced real mushroom toxins poisoning. At the admission to the hospital, in patients with the latent time > 6 hours, a pathological PT (protrombine time) was established only in women, leukocytosis in both women and children, increased concentration of GGT (gamma-glutamin-transferase) in men, increased AST (aspartate-aminotransferase) and ALT (alanin-aminotransferase) only in women, and increased urea in both women and children. After 24 hours, control measuring established high values of AST and ALT extended PT uremia and exalted amount of ammonia in blood in 11 of patients (2 men, 7 women and 2 children). They had severe liver and kidney damage, the most probably caused by Amanita phalloides toxins. The latent time lasted 9 to 13 hours. Of the 11 above mentioned patients, 2 women, aged 74 and 43, and one girl, aged 6, died. No pathological laboratory parameters were established in 40 of subjects with the latent time of 6 and more hours, and the disease manifested through vomiting and diarrhea that lasted for several days. These subjects most probably suffered from mushroom toxins poisoning. Mushroom toxins irritate the mucuous membrane of the gastrointestinal tract, and there are many such poisonous mushrooms. There were no mortalities in this group of subjects.     

Combined metabolic activity within an atrazine-mineralizing community enriched from agrochemical factory soil

The main objective of this work was to characterize an atrazine-mineralizing community originating from agrochemical factory soil, especially to elucidate the catabolic pathway and individual metabolic and genetic potentials of culturable members. A stable four-member bacterial community, characterized by colony morphology and 16S rDNA sequencing, was rapidly able to mineralize atrazine to CO₂ and NH₃. Two primary organisms were identified as Arthrobacter species (ATZ1 and ATZ2) and two secondary organisms (CA1 and CA2) belonged to the genera Ochrobactrum and Pseudomonas, respectively. PCR assessment of atrazine-degrading genetic potential of the community, revealed the presence of trzN, trzD, atzB and atzC genes. Isolates ATZ1 and ATZ2 were capable of dechlorinating atrazine to hydroxyatrazine and contained the trzN gene. ATZ2 further degraded hydroxyatrazine to cyanuric acid and contained atzB and atzC genes whereas ATZ1 contained atzC but not atzB. Isolates CA1 and CA2 grew on cyanuric acid and contained the trzD gene. Complete atrazine degradation was a result of the combined metabolic attack on the atrazine molecule, and complex interactions may exist between the community members sharing carbon and nitrogen from atrazine mineralization.Scientific relevance: Despite numerous reports on atrazine degradation by pure bacterial cultures, the pathways and the atrazine-degrading gene combinations harboured by bacterial communities are only poorly described. In this work, we characterized a four-member atrazine-mineralizing community enriched from an agrochemical factory soil, which was capable of rapidly metabolizing atrazine to CO₂. This study will contribute towards better understanding of the genetic potential and metabolic activities of atrazine-degrading communities, which are generally considered to be responsible for atrazine mineralization in the natural environment.     

Membranous aggregations associated with nuclei inAspergillus flavus hyphae

Summary Different growth regions of young vegetative hyphae ofAspergillus flavus manifested structural modification of certain organelles, especially nuclei. In the apical and subapical zones the interphase nuclei had a normal, non-modified structure. In the region which was a few millimeters distant from the hyphal tip, besides normal nuclei there were some with altered morphology.Such an altered nucleus had electron lucent nuclear content and a membranous aggregate stacked against the nuclear membrane. The aggregate was made of flat, parallel membranes of smooth endoplasmic reticulum (ER). The membranous aggregate was also found in-between two nuclei and the stacking of membranes was highly orderly.