Data from Multiple Portable XRF Units and Their Significance for Ancient Glass Studies

X-ray fluorescence spectroscopy is a non-destructive technique employed for elemental analysis of a wide range of materials. Its advantages are especially valued in archaeometry, where portable instruments are available. Considering ancient glass, such instruments allow for the detection of some major, minor, and trace elements linked to the deliberate addition of specific components or to impurities in the raw materials of the glass batch. Besides some undoubted advantages, portable XRF (p-XRF) has some limitations that are addressed in this study. The performance assessment of four different p-XRF units and the reconciling of their output were conducted. The results show the limitations in cross-referencing the data obtained from each unit and suggest procedures to overcome the issues. The p-XRF units were tested on the set of Corning reference glasses and on a small set of archaeological glasses with known composition. The compatibility of the output was assessed using multivariate statistical tools. Such a workflow allows us to consider data from multiple sources in the same frame of reference.

Influence of speciation distribution and particle size on heavy metal leaching from MSWI fly ash

Fly ash from municipal solid waste incineration (MSWI-FA) contains leachable heavy metals. In the present study the correlations between heavy metal content, particle size, speciation distribution with respect to water leaching are investigated, using a combination of solid-state bulk analytical techniques, leaching treatments, sequential extractions and thermodynamic geochemical modelling. Among the analyzed heavy metals, Zn and Pb are the most abundant in any grain size class, followed by Cu, Cr, Cd and Ni, with concentration that tends to increase with a decrease of the grain size. The phase composition is constituted of salt (halite, sylvite, anhydrite and syngenite), which provide the main minerals regardless of the particle size class; calcite, quartz and gehlenite occur in comparatively lower amounts, while 50% wt is composed of amorphous fraction. Heavy metal leaching is strongly correlated to speciation distribution, and in particular to the fraction (F1) associated with salt, carbonate and weak surface sorption. Leaching from speciation due to surface complexation on Al/Fe (hydr)oxide becomes relevant at acidic regime. Particle size and heavy metal content, in turn, moderately correlate with leaching. The F1-speciation as a function of particle size does not exhibit a definite trend shared by all heavy metals under investigation. This suggests that i) differences in speciation distribution, rather than bare heavy metal content or particle size, govern leaching from MSWI-FA; ii) F1 can be regarded as a marker of the potential heavy metal leaching; iii) a comparatively modest efficiency in managing MSWI-FA is expected from grain size separation strategies.

Sintered and 3D-Printed Bulks of MgB2-Based Materials with Antimicrobial Properties

Pristine high-density bulk disks of MgB₂ with added hexagonal BN (10 wt.%) were prepared using spark plasma sintering. The BN-added samples are machinable by chipping them into desired geometries. Complex shapes of different sizes can also be obtained by the 3D printing of polylactic acid filaments embedded with MgB₂ powder particles (10 wt.%). Our present work aims to assess antimicrobial activity quantified as viable cells (CFU/mL) vs. time of sintered and 3D-printed materials. In vitro antimicrobial tests were performed against the bacterial strains Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, Staphylococcus aureus ATCC 25923, Enterococcus faecium DSM 13590, and Enterococcus faecalis ATCC 29212; and the yeast strain Candida parapsilosis ATCC 22019. The antimicrobial effects were found to depend on the tested samples and microbes, with E. faecium being the most resistant and E. coli the most susceptible.

Antimicrobial Activity of MgB2 Powders Produced via Reactive Liquid Infiltration Method

We report for the first time on the antimicrobial activity of MgB2 powders produced via the Reactive Liquid Infiltration (RLI) process. Samples with MgB2 wt.% ranging from 2% to 99% were obtained and characterized, observing different levels of grain aggregation and of impurity phases. Their antimicrobial activity was tested against Staphylococcus aureus ATCC BAA 1026, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. A general correlation is observed between the antibacterial activity and the MgB2 wt.%, but the sample microstructure also appears to be very important. RLI-MgB2 powders show better performances compared to commercial powders against microbial strains in the planktonic form, and their activity against biofilms is also very similar.

Mythic dyes or mythic colour? New insight into the use of purple dyes on codices

The traditional knowledge concerning the use of Tyrian purple in Late Antique and Medieval purple codices - those precious biblical texts written with noble metal inks on parchment dyed or painted with purple colourants - is here updated in view of new analytical evidence. Recent literature reports the analysis carried out on some purple codices, suggesting that Tyrian purple has not, if ever, been used in their making. A large number of purple codices has been considered in this work to elucidate the nature of the purple colour. Results have been discussed within the frame of previous information, thus covering a vast majority of the purple codices presently identified. In most of the instances the use of less expensive dyes such as folium or orchil is suggested. Moreover, analytical results from a non-invasive spectroscopic approach have been definitely confirmed by micro-invasive surface-enhanced Raman analysis performed on micro samples of purple parchment taken from two 6th century codices.

Structural and functional modifications induced by X-ray nanopatterning in Bi-2212 single crystals

X-ray nanopatterning induces both mosaicity increase and oxygen depletion in the high-T_c superconductor Bi₂Sr₂CaCu₂O_8+δ.

Analytical investigations on the Coronation Gospels manuscript

The Coronation Gospels or Krönungsevangeliar is a manuscript kept in Vienna at the Kunsthistorisches Museum Wien, datable to the end of VIII century A.D. and produced at Charlemagne court. It is an example of a purple codex, i.e. its parchment is coloured in purple. It has to be considered as one of the most important medieval codices, according to its use to take oath in the coronation ceremony of kings and emperors of the Holy Roman Empire up to 1792. In order to gather information of the manufacture of the manuscript and its present conservation state, a diagnostic investigation campaign has been carried out in situ with totally non-invasive techniques. X-ray Fluorescence Spectrometry (XRF), UV-visible diffuse reflectance spectrophotometry with optical fibres (FORS), spectrofluorimetry, optical microscopy and multispectral analysis have been applied in order to identify the colourants used in the decoration of the manuscript, with the main concern to the dye used to impart the purple hue to the parchment. The information collected was useful in order to address some of the questions raised by art historians concerning its history.

On the identification of folium and orchil on illuminated manuscripts

The identification of the two purple dyes folium and orchil has rarely been reported in the analysis of painted artworks, especially when analysing illuminated manuscripts. This is not consistent with the fact that ancient literary sources suggested their use as substitutes for the more expensive Tyrian purple dye. By employing non-invasive spectroscopic techniques, the present work demonstrates that these dyes were actually widely used in the production of ancient manuscripts. By employing UV-visible diffuse reflectance spectrophotometry with optic fibres (FORS) and spectrofluorimetry, the abundant identification of both dyes on medieval manuscripts was performed by comparing the spectra recorded on ancient codices with those obtained on accurate replicas of dyed or painted parchment. Moreover, examples are also reported whereby the considered purple dyes were used in mixtures with other colourants. The overall information obtained here allowed us to define new boundaries for the time range in which orchil and folium dyes were used which is wider than previously thought, and to focus on their particular uses in the decoration of books.

Effect of Al and Ca co-doping, in the presence of Te, in superconducting YBCO whiskers growth

High-T_c superconducting cuprates (HTSC) such as YBa₂Cu₃O_7 - x (YBCO) are promising candidates for solid-state THz applications based on stacks of intrinsic Josephson junctions (IJJs) with atomic thickness. In view of future exploitation of IJJs, high-quality superconducting YBCO tape-like single crystals (whiskers) have been synthesized from Ca-Al-doped precursors in the presence of Te. The main aim of this paper is to determine the importance of the simultaneous use of Al, Te and Ca in promoting YBCO whiskers growth with good superconducting properties (T_c = 79-84 K). Further, single-crystal X-ray diffraction (SC-XRD) refinements of tetragonal YBCO whiskers (P4/mmm) are reported to fill the literature lack of YBCO structure investigations. All the as-grown whiskers have also been investigated by means of X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Our results demonstrate that the interplay of Ca, Te and Al elements is clearly necessary in order to obtain superconducting YBCO whiskers. The data obtained from SC-XRD analyses confirm the highly crystalline nature of the whiskers grown. Ca and Al enter the structure by replacing the Y and the octahedral coordinated Cu1 site, respectively, as in other similar orthorhombic compounds, while Te does not enter the structure of whiskers but its presence in the precursor is essential to the growth of the crystals.

Direct-Write X-ray Nanopatterning: A Proof of Concept Josephson Device on Bi2Sr2CaCu2O8+δ Superconducting Oxide

We describe the first use of a novel photoresist-free X-ray nanopatterning technique to fabricate an electronic device. We have produced a proof-of-concept device consisting of a few Josephson junctions by irradiating microcrystals of the Bi2Sr2CaCu2O8+δ (Bi-2212) superconducting oxide with a 17.6 keV synchrotron nanobeam. Fully functional devices have been obtained by locally turning the material into a nonsuperconducting state by means of hard X-ray exposure. Nano-XRD patterns reveal that the crystallinity is substantially preserved in the irradiated areas that there is no evidence of macroscopic crystal disruption. Indications are that O ions have been removed from the crystals, which could make this technique interesting also for other oxide materials. Direct-write X-ray nanopatterning represents a promising fabrication method exploiting material/material rather than vacuum/material interfaces, with the potential for nanometric resolution, improved mechanical stability, enhanced depth of patterning, and absence of chemical contamination with respect to traditional lithographic techniques.

A diagnostic study on folium and orchil dyes with non-invasive and micro-destructive methods

Folium and orchil are dyes of vegetal origin. Folium is obtained from Chrozophora tinctoria (L.) A. Juss., whereas orchil is obtained from Roccella and other genera of lichens. These dyes were used in the past to impart purple hue to paintings and textiles as substitutes for the more prised Tyrian purple dye, obtained from shellfish. Despite several citations in ancient technical treatises dating back at least to the Greek-Roman age, the identification of these dyes in artworks is rare. In the case of folium, an additional drawback is that its composition is presently unknown. In this work different non-invasive (FT-IR, FT-Raman, fibre optic reflectance spectrophotometry, spectrofluorimetry, X-ray fluorescence spectrometry) and micro-invasive (surface enhanced Raman spectroscopy, matrix assisted laser desorption ionisation-time of flight-mass spectrometry, inductively coupled plasma-mass spectrometry) techniques were used in order to increase the diagnostic information available on these dyes. Measurements were carried out on the dyes extracted from raw materials and on painted or dyed parchments. The possibility to distinguish between folium and orchil by chemical analysis is discussed.

CrisDi School: disseminating crystallography in Piedmont, Italy

The Interdepartmental Research Centre for the Development of Crystallography (CrisDi) aims to be an institution of reference for researchers at the University of Turin interested on the field of diffraction (X-rays, neutrons and electrons), to promote the knowledge and dissemination of crystallography, and to facilitate the access to available laboratory instrumentation (diffractometers and TEM) and to large scale facilities (synchrotron and neutron sources). CrisDi hosts scientists with interest in the fields of solid state chemistry and physics, organic, inorganic, organometallic and theoretical chemistry, mineralogy, biology, pharmaceutical and agricultural sciences. The Centre encourages the design and the development of new methodologies and applications, and supports the enhancement of the available instruments. The submission of proposals at large scale instruments is encouraged specially for young researchers and PhD students. The cultural and scientific interchange among crystallographers coming from different disciplines is strongly encouraged by CrisDi. A main task of the CrisDi is the annual organization of a post-grade level School with a series of courses dedicated to: (i) basic level crystallography (symmetry, theory of diffraction, crystal-chemistry), diffraction techniques (single crystal and powder X-ray diffraction, neutron and electron scattering); (ii) advanced level (high temperature and high pressure structural studies, macromolecular crystallography, time resolved crystallography and kinetic studies); (iii) spectroscopic approaches (XAFS, XANES, XES and NMR) in crystallography. The school, which is held every year in May for about 20 ECTS equivalent, has no tuition fees and is also open to non-academia people.

X-ray crystal structures of Al-doped (Y,Ca)Ba2Cu3O(7-y) whiskers

Al(+3)-doped (Y,Ca)Ba2Cu3O(7-y) (YBCO) whiskers have been synthesized using a solid-state reaction technique. These materials are promising candidates for solid-state THz applications based on sequences of Josephson Junctions (IJJs). Alumina addition was systematically varied and the effect of aluminium incorporation on the structure has been investigated using single-crystal X-ray diffraction. Aluminium only replaces Cu atoms in the O-Cu-O-Cu chains and a gradual transition from orthorhombic to tetragonal space group occurs, thus increasing the Al content. A gradual modification of the coordination sphere of the copper site has also been observed. The Ca(2+) ion substitutes mainly the Y(3+) ion and also, to a small extent, the Ba(2+) ion.

Doping change in the Bi-2212 superconductor directly induced by a hard X-ray nanobeam

We describe the controlled use of a 17 keV X-ray synchrotron nanobeam to progressively change the oxygen doping level in Bi-2212 superconducting whisker-like single crystals. Our data combine structural and electrical information collected on the same crystals, showing a maximum change in the critical temperature Tc of 1.3 K and a maximum elongation of ∼1 Å in the c-axis length, compared to the as-grown conditions. Simulations of our experimental conditions by means of a finite element model exclude local heating induced by the X-ray nanobeam as a possible cause for the change in the doping level and suggest an important role of secondary electrons. These findings support the possible use of hard X-rays as a novel direct-writing, photoresist-free lithographic process for the fabrication of superconducting devices, with potential nanometric resolution and 3D capability.

Non-invasive investigation on a VI century purple codex from Brescia, Italy

Purple codices are among the most relevant and prestigious book productions of Late Antique and Medieval age. They usually contained texts from Holy Writings written with golden or silver inks on parchment dyed in a purple hue. According to the tradition, the colour of parchment was obtained by the well renowned Tyrian purple dye. From the material point of view, however, very little is known about the compounds actually used in the manufacture of these manuscripts. Presently, the information available is limited to the ancient art treatises, with very few diagnostic evidences supporting them and, moreover, none confirming the presence of Tyrian purple. It is more than apparent, then, the need to have at disposal larger and more complete information at the concern, in order to verify what came to us from the literary tradition only. In this study, preliminary results are presented from non-invasive investigation on a VI century purple codex, the so-called CodexBrixianus, held in the Biblioteca Civica Queriniana at Brescia (Italy). Analyses were carried out with XRF spectrometry, UV-visible diffuse reflectance spectrophotometry, molecular spectrofluorimetry and optical microscopy. The results suggest the hypothesis that Tyrian purple had been used as a minor component mixed with other less precious dyes such as folium or orchil.

First analytical evidences of precious colourants on Mediterranean illuminated manuscripts

Two Byzantine VI century manuscripts known as Vienna Dioskurides and Vienna Genesis, held in the Austrian National Library at Vienna, were analysed with in situ non-invasive techniques. Raman spectroscopy, UV-Vis diffuse reflectance spectrophotometry with optic fibres and X-ray fluorescence spectrometry were used to characterise the palette of these early Middle Ages manuscripts. The analytical study was performed to have a better knowledge on the colourants used by ancient miniature painters, a subject known more on the basis of traditional sources (i.e. medieval treatises) than of analytical evidences. Indeed these illuminated manuscripts are, to the authors' knowledge, among the oldest ever being analysed, so that the colourants found in them can be considered among the oldest evidences of their use. The main feature of Vienna Dioskurides and Vienna Genesis palettes is their richness, exemplified by the simultaneous presence of gold and ultramarine blue; in Vienna Dioskurides cinnabar is also present. Information regarding ultramarine blue is surprising, being the analytical evidence of the use of this precious pigment at least three centuries before its use in Western manuscripts, a feature justified by the fact that the Byzantine Empire was the dominant culture in early Middle Ages in the Mediterranean World. Other colourants include azurite and indigo, red lead, orpiment, red and yellow ochres, while a mixture of blue and yellow colourants, known as vergaut, was used to render green hues. Organic colourants were also used, such as madder and Tyrian purple, the latter employed to dye the parchment of Vienna Genesis.

Non invasive analysis of miniature paintings: proposal for an analytical protocol

The characterisation of palettes used in manuscript illumination is a hard analytical task, due to value and fragility of the analysed items. Analysis on miniatures must be necessarily non-invasive and fast and requires the use of several techniques since no single technique is able to provide all information needed. In this work a four-step analytical protocol is proposed for non-invasive in situ characterisation of miniature paintings. The protocol allows the identification of coloured materials through the use in sequence of complementary techniques, so as to fully exploit the information given by each instrument. Preliminarily to the instrumental investigations on ancient books and miniatures is the compilation of spectroscopic databases obtained from "standard" samples prepared on parchment, according to recipes described in medieval artistic treatises. The protocol starts with an extensive investigation with UV-visible spectrophotometry in reflectance mode, collecting spectra from all the most significant painted areas in the manuscript; chemometric classification is then performed on the spectra to highlight areas possibly containing the same materials. The second step involves in-depth inspection of miniatures under optical microscopy that guides the interpretation of reflectance spectra. XRF spectrometry is then performed to characterise pigments and metal layers, to verify the presence of overlapping layers, to identify mordants in lakes and to recognise minor components that may yield information concerning provenance; in addition, chemometric classification can be performed on element concentrations to highlight similar areas. Finally, Raman spectroscopy is used to shed light on the uncertain cases, if still present. Such a procedure offers a wealth of information without causing stress to the manuscripts under analysis.

Effect of intracranial bleeds on the neurocognitive, academic, behavioural and adaptive functioning of boys with haemophilia

Brain insults are a risk factor for neuropsychological and academic deficits across several paediatric conditions. However, little is known about the specific effects of intracranial haemorrhage (ICH) in boys with haemophilia. The study compared neurocognitive, academic and socio-emotional/behavioural outcomes of boys with haemophilia with and without a history of ICH. Of 172 consecutive patients seen at a Pediatric Comprehensive Care Hemophila Centre, 18 had a history of ICH. Sixteen boys between the ages of 3 and 17 years were available for study and were matched to controls with haemophilia of the same age and disease severity and on the basis of maternal education. Groups were compared on neuropsychological and academic outcomes. Attention, socio-emotional function and executive skills were compared using data from parent questionnaires. Differences were found in intellectual function, visual-spatial skill, fine motor dexterity and particularly language-related skills, including vocabulary, word reading and applied math problem solving. Despite these group differences, outcomes were within the average range for most boys with ICH. No group differences were found in behavioural and socio-emotional functioning. Although ICH in haemophilia is not benign, it was not associated with significant cognitive and academic consequences for most boys. Early neuropsychological assessment may be indicated when there is a history of ICH. Investigation of age at ICH and quantitative measures of brain in relation to neurocognitive outcomes in larger groups of boys with ICH would be useful.

μ-EXAFS, μ-XRF, and μ-PL characterization of a multi-quantum-well electroabsorption modulated laser realized via selective area growth

In the past few years, strong efforts have been devoted to improving the frequency of optical-fiber communications. In particular, the use of a special kind of integrated optoelectronic device called an electroabsorption modulated laser (EML) allows communication at 10 Gb s(-1) or higher over long propagation spans (up to 80 km). Such devices are realized using the selective area growth (SAG) technique and are based on a multiple quantum well (MQW) distributed-feedback laser (DFB) monolithically integrated with a MQW electroabsorption modulator (EAM). Since the variation in the chemical composition between these two structures takes place on the micrometer scale, in order to study the spatial variation of the relevant parameters of the MQW EML structures, the X-ray microbeam available at the ESRF ID22 beamline is used. The effectiveness of the SAG technique in modulating the chemical composition of the quaternary alloy is proven by a micrometer-resolved X-ray fluorescence (μ-XRF) map. Here, reported micrometer-resolved extended X-ray absorption fine structure (μ-EXAFS) spectra represent the state of the art of μ-EXAFS achievable at third-generation synchrotron radiation sources. The results are in qualitative agreement with X-ray diffraction (XRD) and micrometer-resolved photoluminescence (μ-PL) data, but a technical improvement is still crucial in order to make μ-EXAFS really quantitative on such complex heterostructures.

Synchrotron study of oxygen depletion in a Bi-2212 whisker annealed at 363 K

Direct evidence is reported of structural and electronic effects induced on a single Bi(2)Sr(2)CaCu(2)O(8+delta) (Bi-2212) whisker during a progressive annealing process. The crystal was investigated by micro X-ray diffraction (micro-XRD), micro X-ray fluorescence and electrical characterization at the European Synchrotron Radiation Facility, during a series of three in situ thermal processes at 363 K. Each step increased the sample resistivity and decreased its critical temperature, up to a semiconducting behaviour. These data correlate with micro-XRD analysis, which shows an increase of the c-axis parameter from 30.56 A to 30.75 A, indicating an oxygen depletion mechanism. Mild temperature annealing could be an effective process to modulate the intrinsic Josephson junctions' characteristics in Bi-2212 whiskers.

Mutations of ANT1, Twinkle, and POLG1 in sporadic progressive external ophthalmoplegia (PEO)

To verify the impact of mutations in ANT1, Twinkle, and POLG1 genes in sporadic progressive external ophthalmoplegia associated with multiple mitochondrial DNA (mtDNA) deletions, DNA samples from 15 Italian and 12 British patients were screened. Mutations in ANT1 were found in one patient, in Twinkle in two patients, and in POLG1 in seven patients. Irrespective of the inheritance mode, screening of these genes should be performed in all patients with progressive external ophthalmoplegia with multiple mtDNA deletions.

Novel heteroplasmic mtDNA mutation in a family with heterogeneous clinical presentations

The protean manifestations of a novel maternally inherited point mutation of the mitochondrial genome are reported. The proband showed isolated, spastic paraparesis. A brother, who had suffered from a multisystem progressive disorder, ultimately died of cardiomyopathy. Another brother is healthy. The proband's mother showed truncal ataxia, dysarthria, severe hearing loss, mental regression, ptosis, ophthalmoparesis, distal cyclones, and diabetes mellitus. A muscle biopsy performed in the proband failed to show the morphological abnormalities typical of mitochondrial disorders; the activities of respiratory chain complexes were normal. However, complex I and IV activities were low in the muscle homogenate of the affected mother and brother. Sequence analysis of mtDNA showed a heteroplasmic mutation of the tRNA(Ile) gene (G4284A). The mutation load was approximately 55%, 80%, and 90% in the muscle mtDNA of the proband, his mother, and his affected brother, respectively. Mutation was undetected in the healthy brother, as well as in 100 control samples. Several cybrid clones containing homoplasmic mutant mtDNA from the proband showed significant reductions of complex IV activity and maximum oxygen consumption rate, compared with homoplasmic wild-type clones derived from the same subject.

New splicing-site mutations in the SURF1 gene in Leigh syndrome patients

The gene SURF1 encodes a factor involved in the biogenesis of cytochrome c oxidase, the last complex in the respiratory chain. Mutations of the SURF1 gene result in Leigh syndrome and severe cytochrome c oxidase deficiency. Analysis of seven unrelated patients with cytochrome c oxidase deficiency and typical Leigh syndrome revealed different SURF1 mutations in four of them. Only these four cases had associated demyelinating neuropathy. Three mutations were novel splicing-site mutations that lead to the excision of exon 6. Two different novel heterozygous mutations were found at the same guanine residue at the donor splice site of intron 6; one was a deletion, whereas the other was a transition [588+1G>A]. The third novel splicing-site mutation was a homozygous [516-2_516-1delAG] in intron 5. One patient only had a homozygous polymorphism in the middle of the intron 8 [835+25C>T]. Western blot analysis showed that Surf1 protein was absent in all four patients harboring mutations. Our studies confirm that the SURF1 gene is an important nuclear gene involved in the cytochrome c oxidase deficiency. We also show that Surf1 protein is not implicated in the assembly of other respiratory chain complexes or the pyruvate dehydrogenase complex.

Molecular characterization of HLA class I in Colombians carrying HLA-A2: high allelic diversity and frequency of heterozygotes at the HLA-B locus

Polymerase chain reaction using sequence-specific oligonucleotide probes (PCR-SSOP) typing was used to analyze HLA class I A, B and C alleles in three different Colombian populations. Fifty-nine samples were from Hispano-American Mestizos living in the urban areas of Cali (referred to here as Aso population). Forty-four and thirty samples were from the African Black populations of Zacarias (Zac) and Punta Soldado (PS), respectively. Samples were selected for expression of HLA-A2 by monoclonal antibody staining and allele-specific hybridization, and their HLA-A2 subtype distribution has been reported previously. Although only a limited number of samples was analyzed, the data suggest the existence of a remarkable degree of HLA class I polymorphism in the populations studied, with representatives of most serological classes. Despite their common African origin, the populations Zac and PS, both resident in malaria endemic regions, showed some striking differences in allelic distribution for all three class I loci. Furthermore, the samples from Aso and PS, but not Zac, showed a low percentage of blank alleles at the HLA-B locus (0 and 0.4%, respectively), suggesting the possibility of a heterozygote advantage for HLA-B alleles in Colombian populations.

[Pre-surgical medical therapy of hyperthyroidism]

The Authors analyze the use and the efficacy of antithyroidal drugs administered to the patients affected by hyperthyroidism, that must undergo thyroidectomy. The aim is that the patients arrive to the operation in euthyroidism: this is very important to avoid the complications that can occur during or just after the thyroidectomy. They believe that till today the most effective treatment of hyperthyroidism before thyroidectomy is based on the use of thyonamide and iodine. In case of intolerance to these drugs or if it is necessary an emergency thyroidectomy or in case of a low compliance of the patient, there is the possibility to use different therapeutic approaches with beta-blockers or betametasone plus iopanoic acid and propranolol administered together for a few days. As concerning the possible complications that can occur during or after the thyroidectomy, the Authors analyze in particular the thyrotoxicosis and the "hungry bone" syndrome.

Drug-induced cholestasis. Clinical contribution

We described two cases of drug-induced hepatitis: in both cases we recognised a pathogenesis based on hypersensivity mechanism. The first case, determined by naproxen, presented a serious cholestatic jaundice and histologic pattern due to ductular cholestasis without any inflammatory reaction. The second case, by a-metildopa, was characterized by spread necrosis of liver cells and peri-portal flogistic infiltrated. This chapter of modern epatology is becoming more and more important, because of both the opportunity of studyng physiopathologica mechanism and the increasing morbidity. The peculiarity of these cases was due not only to the morbidity, but also to the seriousnes of clinical symptoms which involved problems of early differential diagnosis and of attentive follow-up.

[Silent myocardial ischemia. Physiopathologic, clinical, and therapeutic considerations and review of the literature]

The need for a modern methodological approach based on recent acquisitions concerning pathophysiology, diagnostics, and therapy of silent ischemic heart disease, as well as the need to establish criteria for prognostic evaluation have prompted the authors to reexamine the subject in light of their own experience and of the current literature.

[Sarcoidosis with pulmonary abscess caused by emerging microorganisms]

The association sarcoidosis-lung abscess due to emerging microorganisms-mycetoma has prompted the authors to report the above clinical case which is interesting in view of the rarity of the disease and of its infective complications. The authors also review the literature on the subject.

Measurement of the Leakage of CO2 from Bundle-Sheath Cells of Leaves during C4 Photosynthesis

During C4 photosynthesis, CO2 is released in bundle-sheath cells by decarboxylation of C4 acids and then refixed via ribulose-1,5-bisphosphate carboxylase. In this study we examined the efficiency of this process by determining the proportion of the released CO2 that diffuses back to mesophyll cells instead of being refixed. This leak of CO2 was assessed by determining the amount of 14CO2 released from leaves during a chase in high [12CO2] following a 70-s pulse in 14CO2. A computer-based analysis of the time-course curve for 14CO2 release indicated a first-order process and provided an estimate of the initial velocity of 14CO2 release from leaves. From this value and the net rate of photosynthesis determined from the 14CO2 fixed in the pulse, the CO2 leak rate from bundle-sheath cells (expressed as a percentage of the rate of CO2 production from C4 acids) could be deduced. For nine species of Gramineae representing the different subgroups of C4 plants and two NAD-malic enzyme-type dicotyledonous species, the CO2 leak ranged between 8 and 14%. However, very high CO2 leak rates (averaging about 27%) were recorded for two NADP-malic enzyme-type dicotyledonous species of Flaveria. The results are discussed in terms of the efficiency of C4 photosynthesis and observed quantum yields.

[Eosinophilic gastroenteritis. A case with predominant involvement of mucosal and muscular layers]

Eosinophilic gastroenteritis is an uncommon disease of unknown aetiology, whose distinctive features are eosinophilia in peripheral blood and eosinophilic infiltration of the bowel wall. Its clinical course shows recurrent crises, even after a period of years, of symptoms that underline the predominant involvement of mucosal, muscular or subserosal layers of the bowel wall. The prognosis of the disease is essentially benign and pharmacologic therapy is not always necessary. A case with predominant involvement of both muscular and mucosal layers is described.

[Rhinocerebral mucormycosis in type 2 diabetes mellitus. Description of a clinical case with favorable outcome]

The case is reported of a 70-year-old man with decompensated non-acidotic type-2 diabetes mellitus and with rhinocerebral mucormycosis, manifested by inflammatory infiltration of the left nasal, paranasal, maxillary, and orbital bone structures with left ophthalmoplegia. The patient was cured after amphotericin B treatment (total dose 2.7 g) and 30 sessions of hyperbaric oxygen (2.8 atmospheres). Cure was confirmed by follow-up over more than 2 years. It is concluded that rhinocerebral mucormycosis must be treated, in addition to control of predisposing factors, and especially by restoring endocrine-metabolic balance, by adequate surgical revision, with specific high-dose amphotericin B treatment and adjunctive hyperbaric oxygen. Further studies are desirable in order to define the advantages of these therapeutic measures.

Photosynthesis in Phosphoenolpyruvate carboxykinase-type C4 plants: mechanism and regulation of C4 acid decarboxylation in bundle sheath cells

The mechanism and regulation of C4 acid decarboxylation in phosphoenolpyruvate (PEP) carboxykinase-type C4 plants was examined in isolated bundle sheath cell strands. These cells decarboxylated added oxaloacetate to PEP at rates exceeding 2.5 mumol min-1 mg-1 chlorophyll when ATP was added. This requirement for ATP could be replaced by malate plus ADP; under these conditions this cytosol-located decarboxylation of oxaloacetate via PEP carboxykinase was sustained by respiratory ATP. It was confirmed that respiratory ATP production was linked primarily to the oxidative decarboxylation of malate via NAD malic enzyme. This process, measured as pyruvate production, was highly dependent on Pi. Besides being required to generate ATP, Pi had a second role which was probably associated with the transport of malate into mitochondria. Maximum rates of malate decarboxylation via NAD malic enzyme substantially exceeded the minimum rates necessary for providing ATP for cytosolic oxaloacetate decarboxylation. When malate was added with oxaloacetate, ADP and Pi rates of malate decarboxylation of between 3 and 4 mumol min-1 mg-1 chlorophyll were recorded. About half of this activity was sustained by the reoxidation of NADH coupled to reduction of oxaloacetate via malate dehydrogenase. When malate was added without oxaloacetic acid, respiration by these bundle sheath cells was stoichiometrically linked with the oxidation of malate to pyruvate. This malate-dependent respiration was stimulated by adding ADP or phosphorylation uncouplers; it was not significantly inhibited by including oxaloacetate. Possible mechanisms of regulation of the partitioning of C4 acid decarboxylation between PEP carboxykinase in the cytosol and mitochondrial NAD malic enzyme are discussed.

A procedure for the purification of thioredoxin-m from leaves of the C4 plant Zea mays

A simple four-step procedure for the purification of thioredoxin-m from Zea mays leaves is described. The procedure provides pure protein with recoveries of 20-25%. This thioredoxin mediates in the regulation of NADP-malate dehydrogenase involved in photosynthesis in C4 plants.

[Scrofula in an elderly woman. A clinical case]

The case is described of an elderly woman with scrofula. The peculiarity of this case consisted in the comparative rarity of primary tubercular lymphadenopathy (a pathology that in the past used to be common in poor socioeconomic conditions) even considering the present renewed diffusion of tuberculosis; especially as this elderly patient had no previous history of tubercular infection.

Bilevel disulfide group reduction in the activation of c(4) leaf nicotinamide adenine dinucleotide phosphate-malate dehydrogenase

The time course of thioredoxin-mediated reductive activation of isolated Zea mays nicotinamide adenine dinucleotide phosphatemalate dehydrogenase is highly sigmoidal in nature. We examined the factors affecting these kinetics, including the thiol-disulfide status of unactivated and activated forms of the enzyme. The maximum steady rate of activation was increased, and the length of the lag in activation decreased, as the concentrations of thioredoxin-m, dithiothreitol, and KCl were increased. The lag in activation (sigmoidicity) was eliminated by preincubating the unactivated enzyme with 100 mm 2-mercaptoethanol; this pretreatment did not activate the enzyme. Unactivated nicotinamide adenine dinucleotide phosphate-malate dehydrogenase was found to contain approximately two SH groups per subunit, increasing to about four SH per subunit after pretreatment with 2-mercaptoethanol and six SH per subunit after activation by incubating the enzyme with dithiothreitol. We suggest that reduction of one particular higher redox potential disulfide group in unactivated nicotinamide adenine dinucleotide phosphate-malate dehydrogenase facilitates the subsequent reduction of the critical S-S group (regulatory S-S) necessary to generate the active form of the enzyme.

[Micropolyarteritis. The modern nosographic picture and a discussion of a clinical case]

Having observed a patient presenting micropolyarteritis with necrotic skin lesions, hypertension and renal injury, the authors had the opportunity to define more closely a disease that only recently has been recognized as a separate nosological entity within the vast and as yet not fully understood field of arterial disorders. In addition, recent literature on the subject is critically reviewed.

Amino Acid Sequence and Molecular Weight of Native NADP Malate Dehydrogenase from the C(4) Plant Zea mays

N-terminus amino acid analysis of purified corn (Zea mays) NADP malate dehydrogenase showed that the mature protein begins at serine-41 of the preprotein sequence and not threonine-58 as previously concluded; therefore, the transit peptide consists of 40 amino acids. The theoretical molecular weight of the mature subunit protein (392 amino acids) is 42,564, agreeing with an experimental value of about 43,000. The molecular weight of the native unactivated (dark form) and activated (light form) of NADP malate dehydrogenase, determined by analytical ultracentrifugation analysis, was about 84,000, indicating that both forms are dimers. However, conventional and high performance liquid chromatography gel filtration procedures indicated apparent molecular weights of about 110,000 to 120,000 for the unactivated native enzyme and about 143,000 to 150,000 for the active enzyme; in these cases, the molecular weight may be overestimated due to the effect of an unusual molecular conformation on the mobility of the enzyme.

Regulation of C4 photosynthesis: modulation of mitochondrial NAD-malic enzyme by adenylates

Effects of adenylates on the activity of mitochondrial NAD-malic enzyme from NAD-malic-enzyme (NAD-ME)-type and phosphoenolpyruvate-carboxykinase-(PKC)-type C4 plants are examined. At physiological concentrations, ATP, ADP, and AMP all inhibit the enzyme from Atriplex spongiosa and Panicum miliaceum (NAD-ME-type plants), with ATP the most inhibitory species. The degree of inhibition is greater with subsaturating levels of activator, malate, and Mn2+. NAD-malic enzyme from Urochloa panicoides (PCK-type) is activated by ATP (up to 10-fold) and inhibited by ADP and AMP. These effects are discussed in relation to regulation of C4 photosynthesis.

[New prospects in the therapeutic use of somatostatin and its derivatives]

The discovery and subsequent clinical application of somatostatine, a polypeptide neurohormone of 14 amino acids, and of its analogs, opens a novel chapter of neuroendocrinology that is still in full evolution and to a large extent unknown. The isolation of an octapeptide, a selective somatostatine analog, permits to prolong its action, in fact it has a halflife of about 140 min in old subjects and about 100 min. in the young. Thanks to its excellent tolerability, the synthetic hormone can be usefully applied in the treatment of acromegaly, gigantism and hypersomatotropinemic conditions in general, and even in other clinical branches, such as treatment of esophageal hemorrhage due to the rupture of varices in liver cirrhosis or to erosion of gastric blood vessels in patients suffering from peptic ulcer disease.

C4 acid decarboxylation and photosynthesis in bundle sheath cells of NAD-malic enzyme-type C4 plants: mechanism and the role of malate and orthophosphate

The mechanism and possible regulation of C4 acid decarboxylation in NAD-malic enzyme-type C4 plants was studied using isolated bundle sheath cells and mitochondria from Panicum miliaceum. Rates of C4 acid-dependent photosynthetic O2 evolution equalled those observed with saturating NaHCO3; the rates ranged from 3 to 5 mumol min-1 (mg chlorophyll)-1. C4 acid-dependent O2 evolution required the addition of aspartate and 2-oxoglutarate (as a source of oxaloacetate) and also malate and orthophosphate. C4 acid decarboxylation by both isolated cells and mitochondria, measured as pyruvate production, also required all four of these components. The scheme previously proposed to account for aspartate decarboxylation in NAD-malic enzyme-type C4 plants does not envisage a role for externally derived malate. However, the mandatory requirement for malate (with orthophosphate), together with the observation that C4 acid decarboxylation is blocked by an inhibitor of the mitochondrial dicarboxylate transporter, suggests that a net flux of malate from outside the mitochondria is required to sustain this process. Arsenate was found to substitute for orthophosphate favoring a role for orthophosphate in malate transport rather than a metabolic one. The results are discussed in terms of likely mitochondrial metabolite transport mechanisms and regulation of the C4 acid decarboxylation process.

Photosynthesis in phosphoenolpyruvate carboxykinase-type C4 plants: activity and role of mitochondria in bundle sheath cells

Mitochondria from bundle sheath cells of the phosphoenolpyruvate carboxykinase-type C4 species Urochloa panicoides were shown to have metabolic properties consistent with a role in C4 photosynthesis predicted from earlier studies. The rate of O2 uptake in response to added malate plus ADP was at least five times the activity observed with NADH, glycine, or succinate. With malate plus ADP the O2 uptake rate averaged about 150 nmol O2 min-1 mg-1 protein, equivalent to about 0.6 mumol min-1 mg-1 of extracted chlorophyll. About half of this activity was apparently phosphorylation-linked with ADP/O2 ratios of about 4. Studies with electron transport inhibitors suggested that about 65% of this malate oxidation is cytochrome oxidase-terminated with a minor component mediated via the alternative oxidase. These mitochondria supported rapid rates of pyruvate production from malate and this activity was also stimulated by ADP but blocked by inhibitors of electron transport. Adding oxaloacetate increased pyruvate production but inhibited O2 uptake. The results were consistent with the notion that in this subgroup of C4 species mitochondrial-located NAD malic enzyme contributes substantially to total C4 acid decarboxylation. This enzyme is apparently also the primary source of NADH necessary to generate the ATP required for phosphoenolpyruvate carboxykinase-mediated oxaloacetate decarboxylation.