Detection of magnetic circular dichroism using a transmission electron microscope.

A material is said to exhibit dichroism if its photon absorption spectrum depends on the polarization of the incident radiation. In the case of X-ray magnetic circular dichroism (XMCD), the absorption cross-section of a ferromagnet or a paramagnet in a magnetic field changes when the helicity of a circularly polarized photon is reversed relative to the magnetization direction. Although similarities between X-ray absorption and electron energy-loss spectroscopy in a transmission electron microscope (TEM) have long been recognized, it has been assumed that extending such equivalence to circular dichroism would require the electron beam in the TEM to be spin-polarized. Recently, it was argued on theoretical grounds that this assumption is probably wrong. Here we report the direct experimental detection of magnetic circular dichroism in a TEM. We compare our measurements of electron energy-loss magnetic chiral dichroism (EMCD) with XMCD spectra obtained from the same specimen that, together with theoretical calculations, show that chiral atomic transitions in a specimen are accessible with inelastic electron scattering under particular scattering conditions. This finding could have important consequences for the study of magnetism on the nanometre and subnanometre scales, as EMCD offers the potential for such spatial resolution down to the nanometre scale while providing depth information--in contrast to X-ray methods, which are mainly surface-sensitive.

Major lipophilic pigments in Atlantic seaweeds as valuable food ingredients: Analysis and assessment of quantification methods.

Current trends towards the use of ingredients from natural origin in food, cosmetic and pharmaceutical industry, place macroalgae as a good reservoir of novel compounds. Among them, lipophilic major pigments such as chlorophylls and fucoxanthin, are of great interest because of their multiple applications as bioactive compounds and dyes. In this work, a mid-polarity medium was used to extract pigments from twenty-four species from North coast of Spain, including brown (Phaeophyceae) and red macroalgae (Rhodophyta). The fucoxanthin and chlorophyll a content was assessed by means of two different methods, spectrophotometric and high-performance liquid chromatography coupled to diode array detection (HPLC-DAD). The effect of dried processing on the pigment content of selected species was also evaluated. A linear relationship between the extractability of fucoxanthin and chlorophyll a was observed, being the highest content recorded among members belonging to the order Fucales and Undaria pinnatifida. This work provides good insights about the content on pigments in Spanish North Atlantic macroalgae with future commercial value in different industrial fields, as well as a critical overview of the suitability of the quantification methods and challenges related to their effect in results evaluation.

Asymmetry of the two-beam geometry in EMCD experiments.

We analyse theoretically the influence of the asymmetry of the two-beam geometry on quantitative measurements of the energy-loss magnetic chiral dichroism. Our simulations indicate that this asymmetry is not very strong inside or close to the Thales circle, but in other regions of the diffraction plane it can hinder an accurate extraction of the orbital to spin moment ratio.

Bacteraemia with pleural effusions complicating typhoid fever caused by high-level ciprofloxacin-resistant Salmonella enterica serotype Typhi.

An unusual case of bacteraemia with bilateral pleural effusion caused by Salmonella enterica serotype Typhi in a 10-year-old previously healthy girl is reported. The organism was isolated from pleural fluid aspirate and from blood, and exhibited high-level ciprofloxacin resistance (MIC 16 µg/ml) associated with triple mutations in the QRDRs of the gyrA and parC genes leading to the amino-acid changes Ser83→Phe and Asp87→Asn in gyrA and Ser80→Ile in parC. The patient was successfully treated with parenteral ceftriaxone and intercostal chest tube drainage. The case is notable because of the important issue of antimicrobial resistance in S. Typhi and the therapeutic dilemma faced by clinicians regarding the empirical use of ciprofloxacin and newer fluoroquinolones.

Location of actin, myosin, and microtubular structures during directed locomotion of Dictyostelium amebae.

During their life cycle, amebae of the cellular slime mould Dictyostelium discoideum aggregate to form multicellular structures in which differentiation takes place. Aggregation depends upon the release of chemotactic signals of 3',5'-cAMP from aggregation centers. In response to the signals, aggregating amebae elongate, actively more toward the attractive source, and may be easily identified from the other cells because of their polarized appearance. To examine the role of cytoskeletal components during ameboid locomotion, immunofluorescence microscopy with antibodies to actin, myosin, and to a microtubule-associated component was used. In addition, rhodamine-labeled phallotoxin was employed. Actin and myosin display a rather uniform distribution in rounded unstretched cells. In polarized locomoting cells, actin fluorescence (due to both labeled phallotoxin and specific antibody) is prevalently concentrated in the anterior pseudopod while myosin fluorescence appears to be excluded from the pseudopod. Similarly, microtubules in locomoting cells are excluded from the leading pseudopod. The cell nucleus is attached to the microtubule network by way of a nucleus-associated organelle serving as a microtubule-organizing center and seems to be maintained in a rather fixed position by the microtubules. These findings, together with available morphological and biochemical evidences, are consistent with a mechanism in which polymerized actin is moved into the pseudopod through its interaction with myosin at the base of the pseudopod. Microtubules, apparently, do not actively participate in movement but seem to behave as anchorage structures for the nucleus and possibly other cytoplasmic organelles.

Magnetic circular dichroism in electron energy loss spectrometry.

The measurement of circular dichroism in the electron microscope is a new, emerging method and, as such, it is subject to constant refinement and improvement. Different ways can be envisaged to record the signal. We present an overview of the key steps in the energy-loss magnetic chiral dichroism (EMCD) experiment as well as a detailed review of the methods used in the intrinsic way where the specimen is used as a beam splitter. Lateral resolution up to 20-30 nm can be achieved, and the use of convergent beam techniques leads to an improved S/N ratio. Dichroic effects are shown for Ni and Co single crystal; as a counterexample, measurements were carried also for a non-magnetic (Ti) sample, where no dichroic effect was found.

Optimal aperture sizes and positions for EMCD experiments.

The signal-to-noise ratio (SNR) in energy-loss magnetic chiral dichroism (EMCD)--the equivalent of X-ray magnetic circular dichroism (XMCD) in the electron microscope--is optimized with respect to the detector shape, size and position. We show that an important increase in SNR over previous experiments can be obtained when taking much larger detector sizes. We determine the ideal shape of the detector but also show that round apertures are a good compromise if placed in their optimal position. We develop the theory for a simple analytical description of the EMCD experiment and then apply it to dynamical multibeam Bloch wave calculations and to an experimental data set. In all cases it is shown that a significant and welcome improvement of the SNR is possible.

Mono- and polynuclear complexes of Pt(II) with polypyridyl ligands. Synthesis, spectroscopic and structural characterization and cytotoxic activity.

An array of poly- and mononuclear complexes of Pt(II) with polypyridyl ligands is reported. The framework complexes [(PtCl(2))(2)(bpp)(2)(micro-PtCl(2))](H(2)O)(2) [bpp=2,3-bis(2-pyridyl)pyrazine], [PtCl(2)(micro-tptz)PtClNCPh]Cl [tptz=2,4,6-tris(2-pyridyl)-1,3,5-triazine], and mononuclear PtCl(2)(NH(2)dpt) [NH(2)dpt=4-amino-3,5-bis(2-pyridyl)-1,2,4-triazole] have been prepared and structurally characterized. Both neutral and ionic complexes are present, with bifunctional and monofunctional Pt(II) moieties, whose size and shape enable them to behave as novel scaffolds for DNA binding. Pt(II) complexes were tested for their biological activity. Cell viability assay and flow cytometric analysis demonstrated that these complexes, particularly [PtCl(2)(micro-tptz)PtClNCPh]Cl, were effective death inducers in human colon rectal carcinoma HT29 cells and their cytotoxic activity was higher than that exerted by cisplatin. Morphological analysis of treated HT29 cells, performed by fluorescence microscopy after Hoechst 33258 staining, showed the appearance of the typical features of apoptosis. Moreover, our results suggested that mitochondria are involved in apoptosis induced by Pt(II) complexes in HT29 cells as demonstrated by dissipation of mitochondrial transmembrane potential.

Approach to the correction of drooping tip: common problems and solutions.

The drooping tip deformity is both a bothersome aesthetic feature and functional impairment of the nose. Both static and dynamic factors may affect tip appearance and it seems logical to take into account these factors when planning correction of drooping tip. Many studies have examined this topic, but its treatment remains controversial. In order to make nasal tip surgery successful, it is useful to identify the keystone anatomical characteristics of the tip itself. Naso-labial angle, nostril axis, tip rotation angle according to Frankfort plane and columellar-facial angle may be measured to assess nasal tip position. The present study focuses on the authors' personal experience on the key anatomic changes of the nose that deserve correction and on the main surgical steps needed to achieve consistent results when dealing with a drooping tip. Pre- and post-operative nasal tip rotation and projection were studied. Correction of the drooping tip was accomplished by an open or closed septorhinoplasty approach according to patient's needs. The surgical techniques mostly employed for tip repositioning was septum straightening (41/41) and tongue-in-groove (36/41 cases) (87.8%). A columellar strut was used in 8/41 (19.51%) cases. LLC cephalic resection was applied in 29/41 patients (70.73%), LLC re-orienting sutures were made in 18/41 cases (43.9%) and lateral crural overlay was needed in 2/41 (4.8%). The key anatomic changes of the nose that deserve correction and the surgical steps needed to ease the often intriguing pre-operative decision-making process are reviewed.

Impact of self-administered cocaine and cocaine cues on extracellular dopamine in mesolimbic and sensorimotor striatum in rhesus monkeys.

Studies were conducted to determine the impact of self-administered cocaine on extracellular striatal dopamine in four rhesus monkeys. The extent to which external cue conditioning contributed to the effects of cocaine and whether there is activation of striatal dopaminergic neurotransmission during drug-seeking behavior was also examined. Microdialysis measurements were made at 2 min intervals in sensorimotor (dorsolateral) and mesolimbic (central and ventromedial) striatum. A fixed-ratio schedule of reinforcement was used, with cocaine availability signaled by a visual cue. Studies examined the effects of cocaine or cocaine cues against a drug-free baseline. Large (fivefold to eightfold) increases in extracellular dopamine after a self-administered infusion of 0.5 mg/kg cocaine were quite rapid and matched the time course of reported subjective effects in human laboratory studies. To determine if conditioning to external cues contributed to the cocaine-induced increases, saline was substituted for cocaine in the infusion, leaving all other visual and auditory stimuli unchanged. No increase in extracellular dopamine in either sensorimotor or mesolimbic striatal subdivisions was observed. Extracellular dopamine during extended periods of drug-seeking behavior triggered by a visual cue was determined in both central and ventromedial striatum. This procedure also did not result in any measurable changes in extracellular dopamine. These studies demonstrate rapid and pronounced pharmacological actions of self-administered cocaine. No apparent conditioned component of those actions was associated with external environmental cues, suggesting that cues that trigger drug-seeking behavior in nonhuman primates do not cause conditioned increases in mesolimbic striatal dopamine.

The cytoskeleton of hydatid cyst cultured cells and its sensitivity to inhibitors.

Cell cultures obtained from the germinal layer of hydatid cysts of the parasitic tapeworm Echinococcus granulosus were characterized with respect to their microtubule and microfilament systems. These were stained using monospecific antibodies against tubulin from sea urchin spermatozoa or sheep brain and against Dictyostelium discoideum actin as well as rhodamine conjugated phalloidin. The results show that the distribution of microtubules nad actin containing fibres of these cells is remarkably similar to that of mammalian cells both during interphase and mitosis. Hydatid cells, however, could not be stained with a specific antivimentin antibody. Indirect immunofluorescence with antitubulin antibodies of inhibitor treated cells shows that hydatid cell microtubules are sensitive to several antimicrotubular drugs including benzimidazole derivatives, colchicine, vinblastine, and griseofulvin.

Diagnosis of an intact hydatidiform mole with coexistent fetus by amniography.

A case hydatidiform mole with coexistent living fetus is presented and the steps by which the diagnosis was reached are given prominence. The diagnosis in utero of an intact hydatidiform mole with associated fetus is extremely difficult, and the author thinks that the most useful diagnostic means for this rare situation is amniography.

Role of the Salmonella abortusovis virulence plasmid in the infection of BALB/c mice.

Following oral inoculation of BALB/c mice, Salmonella abortusovis strain SS44 was recovered in lower numbers from the Peyer's patches and mesenteric lymph nodes compared with S. typhimurium strain SL1344, whereas splenic infections were equivalent between the two serovars. SS44 was cured of its virulence plasmid or subjected to mutagenesis of the spv genes, and the Spv(-) derivatives were tested for virulence in mice. Plasmid-cured S. abortusovis SU40 retained virulence in BALB/c mice when inoculated intraperitoneally. On the other hand, mice infected orally with SU40 had greatly reduced splenic infection compared to those infected with wild-type SS44. Similar results were obtained after Tn5 insertion mutagenesis of the spvR gene or deletion of the spvABCD locus. These results suggest that in the gut-associated lymphoid tissues S. abortusovis may replicate less than S. typhimurium and that the S. abortusovis virulence plasmid primarily affects systemic infection after oral inoculation but not after intraperitoneal administration in the mouse model.

Tracking of clinical and environmental Vibrio cholerae O1 strains by combined analysis of the presence of toxin cassette, plasmid content and ERIC PCR.

Clinical and environmental Vibrio cholerae O1 strains associated with the cholera epidemic in the Luanda province of Angola from 1991 to 1994 were tracked by toxin distribution, plasmid content and chromosomal polymorphism of the enterobacterial repetitive intergenic consensus (ERIC) sequences by PCR fingerprinting. To follow the distribution of ace, zot and ctxA toxin genes, 6 specific PCR tests were applied to 100 Vibrio strains, after preliminary hybridization experiments. Clinical isolates of Vibrio cholerae O1 were characterized by high stability of the toxigenic cassette and the presence of a large conjugative multi-resistant plasmid of incompatibility class C. Such characteristics were present in all isolates during the four years of the epidemic. Environmental strains, isolated from the river supplying water to the Luanda population showed three different genetic profiles: the presence of both cassette and plasmid, the presence of cassette only or absence of both. To assess the clonal relationship between the clinical isolates and the three groups of environmental strains, the strains were analyzed by PCR ERIC polymorphism. This analysis, supported by the toxin and plasmid content, suggested the stability of the epidemic strain in clinical cases during the epidemic and led to the finding that there was a strict genetic relationship of the epidemic strain with the environmental ones as characterized by the presence of the toxin cassette. The role of the water supply from Bengo River as a reservoir of the Vibrio epidemic strain is discussed.

Synthesis, characterization, and cytotoxic activity of copper(II) and platinum(II) complexes of 2-benzoylpyrrole and X-ray structure of bis[2-benzoylpyrrolato(N,O)]copper(II).

Copper(II) and platinum(II) complexes of 2-benzoylpyrrole (2-BZPH) were synthesized and characterized with IR, 1H and 13C NMR spectroscopies and coordination geometry with ligands arranged in transoid fashion. The crystal structure of [Cu(II)(2-BZP)2] was determined by X-ray diffraction. Death of complex treated Jurkat cells was measured by flow cytometry. The bis-chelate complexes [Cu(II)(2-BZP)2] and [Pt(II)(2-BZP)2] adopt square-planar coordination geometry with ligands, arranged in transoid fashion. Concentrations of 1-10 microM Platinum(II) complexes reduced cell survival from 100% to 20%, in contrast to the copper(II) complex which caused no cell death at a concentration of 10 microM. While the Pt(II) complexes may have damaged DNA to induce cell death, treatment with the Cu(II) complex did not induce Jurkat cell death.

Neuroendocrine effect of a short-term treatment with DHEA in postmenopausal women.

OBJECTIVES: A progressive decline of plasma dehydroepiandrosterone (DHEA) levels occurs in women during aging related to the reduction of adrenocortical secretion. A specific action of DHEA on the central nervous system (CNS) is suggested by the improvement of psychological and physical well-being in postmenopausal women after DHEA supplementation. The aim of the present study was to investigate the neuroendocrine effects of short-term DHEA supplementation in postmenopausal women, evaluating changes of plasma beta-endorphin (beta-EP) and growth hormone (GH) before and after oral DHEA (100 mg/day) for 7 days in postmenopausal women (n = 6). METHODS: Before and after 7 days of DHEA supplementation, postmenopausal women underwent a neuroendocrine test with clonidine, an alpha 2 presinaptic agonist for adrenergic system (1.25 mg i.v.). Basal plasma DHEA, androstenedione (A), testosterone (T), estrone (E1) and estradiol (E2) levels were evaluated before and after treatment, while plasma beta-EP and GH levels were measured before and 15, 30, 45, 60 and 90 min after clonidine injection. RESULTS: Basal plasma beta-EP and GH levels did not show a significant difference before and after short-term DHEA administration, while circulating A, T, E1 and E2 significantly increased after treatment. The clonidine test induced a significant increase of plasma beta-EP levels in women after receiving DHEA supplementation but not before; conversely, plasma GM levels increased both before and after treatment. CONCLUSIONS: The present study indicates that short-term DHEA supplementation in postmenopausal women is able to restore the impaired response of pituitary beta-EP to clonidine, an alpha 2 presinaptic agonist. According to these data it is possible to hypothesize that DHEA could play a role in the psychological and physical well-being of postmenopausal women acting via a restoration of neuroendocrine control of antero-pituitary beta-EP secretion.

Neuroendocrine effects of different estradiol-progestin regimens in postmenopausal women.

OBJECTIVE: New regimens and routes of administration of hormonal replacement therapy (HRT) in climateric women are becoming available. Since there is no information on the neuroendocrine effects of sequential combined treatment with 17 beta-estradiol and a progestin, the present study evaluated the neuroendocrine, clinical vasomotor and psychological changes before and after different sequential combined HRT regimens (17 beta-estradiol plus nomegestrol acetate, or cyproterone acetate, or vaginal progesterone). Vasomotor and behavioral effects were evaluated by using the Kupperman score, while changes in plasma endorphin (beta-END) levels were used as marker of neuroendocrine effects. METHODS: Postmenopausal women (n = 30) were randomly divided into three groups (ten women for each group); all women received continuous 17 beta-estradiol (50 mg, transdermal) and each group was sequentially treated with different progestins for 12 days/month: group A, cyproterone acetate (5 mg p.o.); group B, nomegestrol acetate (5 mg p.o.); and group C, progesterone (100 mg, vaginal cream). A group of healthy fertile women (n = 8) served as control. Before and after 6 months of HRT, postmenopausal women underwent an evaluation of subjective Kupperman score and two neuroendocrine tests: (a) naloxone (4 mg i.v.) and (b) clonidine (1.25 mg i.v.). Plasma beta-END levels were measured before and at 15, 30, 45, 60 and 90 min after drug injection. Control women were studied by administering the two neuroendocrine tests only once. RESULTS: Postmenopausal women before HRT showed a pathological Kupperman and no changes of plasma beta-END levels in response to the clonidine and naloxone tests score. On the contrary the increase was significant in healthy women. In each of the three groups of treated women both naloxone and clonidine tests induced a significant increase in plasma beta-END levels (P < 0.01). After 6 months of HRT, an improvement of vasomotor and psychological symptoms was shown by a decrease of Kupperman score. CONCLUSIONS: The present study indicates that sequential treatment with transdermal 17 beta-estradiol and progestin, no matter which progestin was used, restores the beta-END release, improves vasomotor and psychological symptoms.

Clonal relations among Salmonella enteritidis phage type 3 outbreak isolates traced by DNA fingerprinting.

Isolates of Salmonella enteritidis PT3, a rare phage type, were recovered from patients and strains were isolated from an outbreak of gastroenteritis that occurred during the summer of 1997 in North-East Sardinia, Italy. To investigate possible clonal involvement in the outbreak and to evaluate the capacity to discriminate among S. enteritidis PT3 strains, a number of molecular typing methods including ribotyping with a mixture of PstI and SphI (PS-ribotyping), PFGE with endonuclease XbaI and RAPD typing with four arbitrary primers was used. The typical XbaI endonuclease generated PFGE pattern also explained the prevalence of highly clonal S. enteritidis PT3 strains in the outbreak and adjacent areas. RAPD fingerprinting with primers OPA 4, OPB 15, OPB17 and P1254 exhibited a single but unique RAPD profile among the outbreak strains from various sources that differed significantly from control strains. The results of this study showed that when an appropriately chosen set of primers is employed, RAPD fingerprinting can be used as an alternative, rapid, highly reproducible technique for tracing the clonal relations of S. enteritidis PT3, and can be more discriminatory than PFGE. Furthermore, this study revealed the possibility of PT3 causing outbreak.

A new technique of vaginal colpopexy.

The correction of a total or partial vaginal prolapse after hysterectomy is often difficult to perform, particularly when the possibility of sexual intercourse must be preserved. A method of vaginal retropubic colpopexy is proposed. In addition to preserving the vaginal functionality, it can be performed for preventive purposes during hysterectomy for uterine prolapse or conspicuous cystorectocele and finally, it corrects the topographic modification of the bladder and of the urethra. This method has had excellent results on 18 patients and relapse has not occurred after two or three years.

[Hepatitis B virus (HBV) infection in health personnel of a hospital for adolescents. Results of a vaccine campaign]. / Infezione da virus-epatite B (HBV) nel personale di assistenza di un ospedale per adolescenti. Risultati di una campagna vaccinale.

The aim of the research is to evaluate the professional risk of the health workers of a pediatric hospital, mainly devoted to the care of adolescents. A seroepidemiological survey was therefore performed during the preliminary screening of an anti-hepatitis-B vaccination program, implemented in a suburban 150-beds pediatric hospital, with a predominance of elective surgery patients. The prevalence of past or ongoing HBV infection in a sample of adolescent inpatient (10-19 years old) in the same institution was known from an another study (13.2%). The prevalence of any HBV marker among 360 workers was 16.3%, lower in males (13.5 versus 17.7% in females), and in those with an higher level of instruction; the prevalence resulted significantly higher with increasing age and length of hospital service. Out of 321 candidates to anti-HBV vaccination 245 employees accepted the procedure (76.3%), significantly more females than males (80% versus 68.9%) and more subjects less than 30 years-old (84.3% versus 62% of subjects more than 40 years-old subjects). Only 13 subjects (5.3%) did not reach a protective titer after the third dose of the plasma-derived vaccine a protective titer. No major adverse event occurred.