A compact-rigid multi-analyser for energy and angle filtering of high-resolution X-ray experiments. Part 2. Efficiency of a single-crystal-comb.

Diffraction instruments using filtering by one or several analyser crystals exist since the 1980s and 1990s at synchrotron radiation sources, but, due to its low efficiency, this filtering is little used on laboratory sources. In order to overcome this limitation, the efficiency of a small diffraction filtering multi-analyzer block (MAD block) realized with a `single-crystal-comb' curved on a rigid support is demonstrated here. The geometry of this curved surface is logarithmic spiral and is optimized to allow multi-filtering over a relatively important diffraction angular range and to be also applicable over an X-ray spectral range. The efficiency of such a small rigid-compact MAD block consisting of this single-crystal-comb generating 20-50 Si(111) single-crystal blades, associated with a block of Soller collimators, is demonstrated. The angle between each crystal is 0.1°, so the measurement range of the comb is 2-5°. The geometry of this system has been optimized for operation with a synchrotron X-ray source over an energy range of 22 keV to 46 keV and could be used with laboratory X-ray sources (Ag Kα1, 22.1 keV). This MAD block complements and exploits the qualities of the `photon-counting' detectors which have very low intrinsic noise. Their joint efficacy is supported by powder pattern measurements of a LaB6 reference sample and of several heterogeneous samples of cultural heritage materials, carried out at 22 keV on the D2AM beamline at the ESRF. Their signal-to-noise ratio is excellent (1000/1) and allows the detection thresholds of the measurements (from 3-1% to 0.1%) to detect minor phases in the studies of `real' heterogeneous materials to be drastically improved.

Molecular structure of a D-homoandrostanyl steroid derivative: single crystal and powder diffraction analyses.

The knowledge of the structure of a molecular crystal is frequently a prerequisite for the understanding of its solid state properties. Even though single-crystal diffractometry is the method of choice when it comes to crystal structure determination, methods using powder diffraction data become more and more competitive. There has been much recent interest in the development of a new generation of "direct-space" approaches that are particularly suited for molecular crystals. The crystallographic structure of a steroid derivative molecule (17,17-di-n-propyl-17a-aza-D-homo-5alpha-androstan-3beta-ol) was obtained in two independent ways: from a single crystal by laboratory X-rays and from a polycrystalline powder by high-resolution synchrotron powder diffraction. The molecule crystallizes in the orthorhombic space group P2(1)2(1)2(1) (a = 6.5346, b = 17.6006 and c = 19.6978 A). Hydrogen bonds form infinite chains of molecules parallel to the c axis.

Effect of prolonged administration of low doses of dietary retinoids on cell-mediated immunity and the growth of transplantable tumors in mice.

A study was conducted on the activity exerted by prolonged dietary supplementation with progressive amounts of retinoids on cell-mediated immune responses and the growth of transplantable tumors in mice. A few groups of BALB/c mice received 0 (group C), 50 (group A 50), 200 (group A 200), 500 (group A 500), and 1,000 (group A 1000) IU retinol palmitate/mouse/day in drinking water for 150 days. At progressive intervals mice from each group were tested for proliferative responses to concanavalin A (Con A), Escherichia coli lipopolysaccharide, interleukin-2, and interferon-gamma release to Con A. Ten mice from each group were also challenged with the 90-100% tumor-inducing dose of 3 distinct transplantable tumors. At the end of the experiment the principal organs were histologically examined, and the accumulation of vitamin A was evaluated. In groups A 200, A 500, and A 1000, an increase in the proliferative responses and production of lymphokines as compared to those in group C occurred after 60-90 days, but vanished after 150 days. The takes of the 3 tumors were impaired when the challenges were performed on days 75 and 150. This enhancement of distinct functions of cellular reactivity and resistance to transplantable tumors showed a linear relationship with the amount of supplemental retinol palmitate for the first 60-90 days. After 150 days, however, these enhancement effects vanished or tended to decrease.

The effect of subinhibitory concentrations of some antibiotics on the hydrophobicity of gram-negative bacteria.

Cell surface hydrophobicity is currently regarded as an important factor in promoting bacterial adherence to a wide variety of surfaces. This feature was investigated in some Gram-negative bacteria isolated from urinary tract infections and the extent to which their surface characteristics were affected by subinhibitory concentrations of some antibiotics was assayed. Surface properties were evaluated using the salting-out technique (SAT) and bacterial absorption to n-hexadecane (BATH). SAT showed that all except 3 Escherichia coli strains were autoaggregating. BATH detected more hydrophobic characteristics in the stationary phase of bacterial growth. Pretreatment with antibiotics generally reduced hydrophobicity and thus affected the initial reversible phase of attachment of bacteria to eukaryotic cells.

Bactericidal effects induced by laser irradiation and haematoporphyrin against gram-positive and gram-negative microorganisms.

Laser irradiation of tissues treated in vivo with haematoporphyrin (Hpr) is known to result in a cytocidal effect, reportedly more pronounced in tumour tissues. To ascertain whether this cytocidal phenomenon can occur not only in eukaryotic but also in prokaryotic cells, the authors devised a model system in vitro consisting of bacterial cultures in liquid and in solid media. Bacteria photosensitized with Hpr were subsequently exposed to laser beams and to daylight; then normal microbiological techniques were used to determine whether any bactericidal effect occurred. Satisfactory results were achieved, particularly against Gram-positive microorganisms; a partial inhibition of Gram-negative microorganisms was also observed.

[Chemistry of cosmetics in antiquity]. / Chimie et maquillage dans l'Antiquité.

Several texts, statues and paintings denote the importance of make up and eye medicines since the earliest periods of Egyptian history. We have investigated cosmetic powders that were preserved in original alabaster and reed containers. Quantitative crystallographic and chemical analysis of the mineral and organic components revealed surprising facts. In addition to the well known galena PbS and cerussite PbCO3, two unexpected constituents have been identified: laurionite PbOHCl and phosgenite Pb2 (CO3) Cl2, which are rare halide minerals found in lead slag only in certain places where the sea water has weathered lead debris left over from silver mining operations in Antiquity. Alteration of natural lead minerals is also unlikely, given the excellent state of conservation of the reed vessels. This evidence indicates that laurionite and phosgenite were synthesised artificially. Support for this statement comes from recipes of medicinal products to be "used in ophthalmology" reported by Greco-Roman authors such as Dioscorides and Pline (1st Century B.C.): silver foam PbO is crushed and mixed with rock salt and sometimes with natron (Na2CO3). The reaction seems to be straightforward. However, our experiments in the laboratory have shown a major difficulty, arising from the concomitant production of alkali, which raises the pH and leads to different products. It follows that the Egyptians very early mastered this kind of chemical synthesis and technology, a fact of great importance in the History of Sciences. Fire-based technology had been mastered to manufacture Egyptian Blue pigments since the third millennium B.C. The present results now suggest that wet chemistry was already known 4000 years ago. This key finding provides a new insight into the chemical technology of far greater antiquity than has previously been believed. Yet, an important question remains relative to the ultimate motivation for these technological developments. If the Egyptians initially only aimed at different nuances of grey, they could use cerussite, an easily accessible mineral, crushed and mixed with galena. Thus, one should seek other motivations; we shall propose to consider a religious-ritual context, ultimately linked to a pharmaceutical aspect.

[The mechanism of action of aminoglycosides]. / Meccanismo d'azione degli aminoglicosidi.

The mechanism of action of aminoglycosides depends on the inhibition of polypeptide synthesis. In fact, some of them such as Streptomycin, Sisomicin and Gentamicin are believed to cause codon misreading, by increasing the incorporation of certain aminoacids into polypeptide in the ribosome-polyribonucleotide system. Their primary site of action seems to be located in the bacterial ribosome system. Experiments with Sisomicin showed that this antibiotic arrest cell growth, aminoacid incorporation and Beta-galactosidase synthesis, but not incorporation of uracil in ribonucleic acid in E. coli cultures. When polypeptide synthesis is directed by endogenous messenger in cell-fre extracts, the antibiotic stimulates the incorporation of some amino acids into protein.

[Biological effects of distamycin A]. / Effetti biologici dell distamicina A.

In the present review are examined different biological effects of Distamycin A, an antibiotic produced by Streptomyces distallicus. This drug is moderately active on bacteria but it is strongly active on DNA viruses and on some Oncornaviruses, moreover it possesses antineoplastic and antimitotic activity at high doses at which it can result tossic and cause immunodepression.

[Evaluation of in vitro antibiotic sensitivity: critical features of the MIC]. / Valutazione della sensibilità "in vitro" agli antibiotici: aspetti critici della MCI.

Current methods for the "in vitro" study of antibiotic activity, as minimum inhibitory concentration, expose bacteria to constant concentrations of antibiotics. The "in vivo" situation is significantly different, since the antibiotic concentration changes with time. Pharmacokinetic models are "in vitro" experimental systems that seek to simulate conditions of exposure of bacteria to antimicrobial agents that exist in blood and tissues. All of these systems are complicated constructions. A new simple "in vitro" kinetic model, based on solid phase growth, is described.

[Toxoplasmosis: comparative serological diagnosis (direct agglutination, complement fixation, hemagglutination inhibition tests) in order to attempt to clarify the diverse periods of infection in man]. / Toxoplasmosi: diagnosi sierologiche comparate (AD, FC, IHA) per tentare di chiarire i diversi periodi dell'infezione nell'uomo.

Large diffusion of human toxoplasmotic infection and consequent injuries that, sometimes, occur in pregnancy and to the newborn, have been and are principal stimulus to study and to set several diagnostic means to specify, directly or indirectly, acute infection and acquired immunity. Serological methods are, at least till now, the best diagnostic means; among these, we have selected 3 methods: IHA (Behring), CF (I.S.M.) and DA (Bio-Mérieux); with which have been tested 125 sera (selected randomly). Obtained results have been elaborated statistically according to some interpretative perspectives which have been considered the most significant. Da test, that had a propensity to understimulation of serum-positive cases, would show a good sensibility about acute or recent infections and would be positive more difficulty about past infections. IHA test, on the contrary, that showed the greatest percentage of erroneously positive results, had, on the whole, a opposite propensity, but it would seem, with some reservations, also adaptable to the search of acute infections. CF test, rather complicated and long, would seem most versatile of three tests fitting well both to the search of past immunity and to serological diagnosis of acute infection, thanks to the new TTE antigen use.

[Fosfomycin, lysine-fosfomycin, arginine-fosfomycin: antibacterial activity in vitro]. / Fosfomicina, lisin-fosfomicina, arginin-fosfomicina: attivita's antibatterica "in vitro".

The antibacterial activity of NaFosfomicin and of two of its aminoacidic derivatives -Lisin-Fosfomycin and Arginin-Fosfomycin- has been determined "in vitro" as MICs and MBCs, on different groups of Bacteria. The results obtained were then statistically analyzed - according to the "t of Student" - in a comparative evaluation of the values between NaFosfomycin-Lisin-Fosfomycin (F-LF); NaFosfomycin-Arginin-Fosfomycin (F-AF); Lisin-Fosfomycin-Arginin-Fosfomycin (LF-AF). From these comparisons, the data found demonstrated no significant differences among the three compounds, for Proteus, Coliforms and Pseudomonas groups, while Salmonella and Staphylococcus Genera showed good differences (P less than 0.05) from the comparison F-AF.

The parasite-host relationship: an immunological game.

In the present paper we have analyzed the host-parasite relationship and the influence of parasite infections on the immune system. In all cases aberrations in either humoral or cellular immune response are observed. Moreover the constant feature of parasite infections is the stimulation of the reticular endothelial system that induce an increased aspecific resistance toward various antigens.

[Novel characteristic of the genus Campylobacter: Campylobacter-like organisms]. / Nuove caratteristiche del genere Campylobacter: I "Campylobacter like organisms".

The first report of human infections due to Campylobacter dates back to 1947. These microorganisms, classified initially as Vibrio, had been known for many years as agents of several diseases in animals. In 1963 they were grouped in the new Genus Campylobacter belonging to Spirillaceae. Campylobacter are ever more important, particularly C. jejuni, which is an ubiquitous agent of diarrhoea in children. Other microorganisms of this Genus, the "gastric Campylobacter-like organisms" type I, otherwise known as Campylobacter pyloridis, are responsible for gastric diseases.