Distribution of a putative cell surface receptor for fibronectin and laminin in the avian embryo

The cell substratum attachment (CSAT) antibody recognizes a 140-kD cell surface receptor complex involved in adhesion to fibronectin (FN) and laminin (LM) (Horwitz, A., K. Duggan, R. Greggs, C. Decker, and C. Buck, 1985, J. Cell Biol., 101:2134-2144). Here, we describe the distribution of the CSAT antigen along with FN and LM in the early avian embryo. At the light microscopic level, the staining patterns for the CSAT receptor and the extracellular matrix molecules to which it binds were largely codistributed. The CSAT antigen was observed on numerous tissues during gastrulation, neurulation, and neural crest migration: for example, the surface of neural crest cells and the basal surface of epithelial tissues such as the ectoderm, neural tube, notochord, and dermomyotome. FN and LM immunoreactivity was observed in the basement membranes surrounding many of these epithelial tissues, as well as around the otic and optic vesicles. In addition, the pathways followed by cranial neural crest cells were lined with FN and LM. In the trunk region, FN and LM were observed surrounding a subpopulation of neural crest cells. However, neither molecule exhibited the selective distribution pattern necessary for a guiding role in trunk neural crest migration. The levels of CSAT, FN, and LM are dynamic in the embryo, perhaps reflecting that the balance of surface-substratum adhesions contributes to initiation, migration, and localization of some neural crest cell populations.

Comparative study of the morphology, aggregation, adherence to glass, and surface-enhanced Raman scattering activity of silver nanoparticles prepared by chemical reduction of Ag+ using citrate and hydroxylamine

Two different silver colloids were prepared by chemical reduction of silver nitrate with trisodium citrate and hydroxylamine hydrochloride to compare their characteristics in relation to their possible use in surface-enhanced Raman scattering (SERS) spectroscopy. The morphology and plasmon resonance of the single nanoparticles and aggregates integrating these colloids were characterized by means of UV-vis absortion spectroscopy and scanning electron microscopy, revealing important differences between each type of nanoparticle as concerns their physical properties. These metallic systems also manifested differences in the aggregation and the adherence to glass surfaces, revealing significant differences in the chemical surface properties of these nanoparticles. SERS and surface-enhanced IR also indicated the presence of interference bands which can overlap the spectra of the analyte, mainly in the case of the citrate colloid. All these differences have an important influence on the applicability of these nanostructured systems in SERS. In fact, the enhancement factor and spectral pattern of the SERS obtained by using alizarin as a molecule probe are different.

The E148Q mutation in the MEFV gene: is it a disease-causing mutation or a sequence variant?

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent attacks of serositis. To date more then 18 mutations responsible for the disease were identified in the MEFV gene, one such a mutation is E148Q in exon 2 of the gene. While screening FMF patients for mutations in the MEFV gene, we have identified 2 individuals parents of 2 unrelated FMF patients, who were homozygous for E148Q mutation. Upon clinical examination they were absolutely disease free and therefore raised the possibility that this mutation is a benign polymorphism rather than a mutation causing disease. To further investigate the role of the E148Q in FMF we analyzed 25 parents of FMF patients and a control group of 70 individuals, Jews of Moroccan extraction to match for ethnicity of the patients. The rate of E148Q in the control group was 6.4%, being 7.8% among the patient group. Among the parents group (obligatory carriers), in addition to the 2 parents that were homozygous E148Q, in 2 families one of the parents was heterozygote for E148Q but transmitted the other allele (apparently with unknown FMF mutation) to the affected child. Two healthy sibs of one of the E148Q homozygous were also homozygous E148Q. These observations are not in accordance to the notion that E148Q is a mutation causing disease.

Generic RT-nested-PCR for detection of flaviviruses using degenerated primers and internal control followed by sequencing for specific identification

Flaviviruses are a widespread and numerous group of arboviruses that can cause serious illness in humans. The continuous and slow spread of certain flaviviruses, such as Dengue viruses, and the recent entry and spread of West Nile virus to the American continent, point to the need to control these infections. This control requires the use of suitable techniques for diagnostic and surveillance programmes. A generic RT-nested-PCR that is, theoretically, able to detect each member of the group has been designed. The identification of the detected virus is carried out by sequencing. The introduction of an internal control would reduce the number of false negative results and could be used to quantify the viral load in clinical samples where the method works well.

Phenotype-genotype correlation in Jewish patients suffering from familial Mediterranean fever (FMF)

Familial Mediterranean Fever is one of the most frequent recessive disease in non-Ashkenazi Jews. The gene responsible for the disease (MEFV) has very recently been identified. The M694V ('MED') mutation was found in about 80% of the FMF Jewish (Iraqi and North African) chromosomes. To see if the presence of this mutation could be correlated with particular traits of the disease, we examined a number of clinical features in a panel of 109 Jewish FMF patients with 0, 1 or 2 MED mutations. We showed that homozygosity for this mutation was significantly associated with a more severe form of the disease. In homozygous patients, the disease started earlier (mean age 6.4 +/- 5 vs 13.6 +/- 8.9) and both arthritis and pleuritis were twice as frequent as in patients with one or no M694V mutation. Moreover, 3/3 patients with amyloidosis displayed two MED mutations. No association was found with fever, peritonitis, response to colchicine and erysipeloid eruption. The present result strongly suggests the potential prognostic value of the presence of this mutation.

Surface-Enhanced Vibrational Study (SEIR and SERS) of Dithiocarbamate Pesticides on Gold Films

Surface-enhanced infrared (SEIR) and surface-enhanced Raman scattering (SERS) spectroscopies are applied to the study of the adsorption on Au films of the dimethyldithiocarbamate derivative fungicides thiram and ziram. The specificity and sensitivity of both techniques in relation to the detection and surface stability of the above compounds is analyzed comparatively. We have found that both fungicides undergo a breakdown when adsorbed on Au films, although this breakdown takes place to a different extent; thiram seems to be less stable than ziram. The sensitivity of infrared techniques is higher, although a lower enhancement in relation to SERS is observed. Whereas the SEIR technique allows the detection of all the adsorbed fungicide forms, SERS displays a high sensitivity toward only certain adsorbed molecules, those that undergo a strong adsorption induced by the fungicide breakdown.

Spatial and temporal changes in the distribution of proteoglycans during avian neural crest development

In this study, we describe the distribution of various classes of proteoglycans and their potential matrix ligand, hyaluronan, during neural crest development in the trunk region of the chicken embryo. Different types of chondroitin and keratan sulfate proteoglycans were recognized using a panel of monoclonal antibodies produced against specific epitopes on their glycosaminoglycan chains. A heparan sulfate proteoglycan was identified by an antibody against its core protein. The distribution of hyaluronan was mapped using a biotinylated fragment that corresponds to the hyaluronan-binding region of cartilage proteoglycans. Four major patterns of proteoglycan immunoreactivity were observed. (1) Chondroitin-6-sulfate-rich proteoglycans and certain keratin sulfate proteoglycans were absent from regions containing migrating neural crest cells, but were present in interstitial matrices and basement membranes along prospective migratory pathways such as the ventral portion of the sclerotome. Although initially distributed uniformly along the rostrocaudal extent of the sclerotome, these proteoglycans became rearranged to the caudal portion of the sclerotome with progressive migration of neural crest cells through the rostral sclerotome and their aggregation into peripheral ganglia. (2) A subset of chondroitin/keratan sulfate proteoglycans bearing primarily unsulfated chondroitin chains was observed exclusively in regions where neural crest cells were absent or delayed from entering, such as the perinotochordal and subepidermal spaces. (3) A subset of chondroitin/keratan sulfate proteoglycans was restricted to the perinotochordal region and, following gangliogenesis, was arranged in a metameric pattern corresponding to the sites where presumptive vertebral arches form. (4) Certain keratan sulfate proteoglycans and a heparan sulfate proteoglycan were observed in basement membranes and in an interstitial matrix uniformly distributed along the rostrocaudal extent of the sclerotome. After gangliogenesis, the neural crest-derived dorsal root and sympathetic ganglia contained both these proteoglycan types, but were essentially free of other chondroitin/keratan-proteoglycan subsets. Hyaluronan generally colocalized with the first set of proteoglycans, but also was concentrated around migrating neural crest cells and was reduced in neural crest-derived ganglia. These observations demonstrate that proteoglycans have diverse and dynamic distributions during times of neural crest development and chondrogenesis of the presumptive vertebrae. In general, chondroitin/keratan sulfate proteoglycans are abundant in regions where neural crest cells are absent, and their segmental distribution inversely correlates with that of neural crest-derived ganglia.

Comparative study of Legionella pneumophila and other nosocomial-acquired pneumonias

We studied, in a prospective way, the characteristics of definitively diagnosed nosocomially acquired pneumonias in our hospital over 36 months. Out of 55 cases, 27 were due to Legionella pneumophila and 28 to other, non-Legionella bacteria. The cases of legionellosis concentrated in July, August, and December. The only risk factors that showed significant differences (p less than 0.05) were general anesthesia and surgery and immunosuppressive disease, which were more frequent in the non-Legionella group, as were chronic liver disease and lowering of consciousness level. The absence of severe underlying disease, chronic or not, was uncommon in both groups, but more frequent in the Legionella group. We observed no differences in the clinical features of the two groups. Mean values of gamma-glutamyltranspeptidase and total bilirubin were higher (p less than 0.05) in the non-Legionella group. The only x-ray data that showed significant difference were pleural effusion, more frequent in the non-Legionella group (p less than 0.02). The mortality rate of legionellosis was 14.6 percent compared to 35.7 percent for the non-Legionella group (p less than 0.05). We conclude that a sure differential diagnosis based on clinical, roentgenographic and analytical features of both groups is not possible. The relatively low mortality rate of the Legionella group, when compared to other series of nosocomial legionellosis, could be due to the standard use of erythromycin in the therapeutic approach to nosocomial-acquired pneumonia in our hospital.

The MICA region determines the first modifier locus in familial Mediterranean fever

OBJECTIVE

Familial Mediterranean fever (FMF) is a genetically recessive inflammatory disease caused by mutations in the MEFV gene. Most patients of non-Ashkenazi Jewish ancestry or those who are homozygous for M694V manifest a severe disease course, but some express a mild form of the disease. We therefore searched for other genes which could possibly be implicated in the disease phenotype. We tested MICA (major histocompatibility complex class I chain-related gene A) because it has been associated with a number of other inflammatory disorders.

METHODS

One hundred fifty FMF probands and their family members were evaluated. The MEFV gene was screened by a combination of denaturing gradient-gel electrophoresis, restriction fragment length polymorphism, and amplification refractory mutation system. The MICA transmembrane polymorphism in exon 5 was analyzed after biotin-labeled polymerase chain reaction products were loaded onto sequencing gels and subjected to autoradiography.

RESULTS

The contribution of MICA to the FMF phenotype was confirmed after adjustment for the patient's ancestry and for the MEFV genotype. MEFV was individually the most important prognostic factor for the disease. However, the impact of M694V homozygosity on the age at disease onset (OR 2.3) was aggravated if patients also inherited MICA-A9 (OR 6.3). In contrast, the frequency of attacks was found to be dramatically reduced (OR 0.16) in patients with MICA-A4.

CONCLUSION

We have identified the first FMF modifier locus, MICA. FMF is the first model of a Mendelian disease associated with MICA. These results clarify, at least partly, the inconsistent phenotype-MEFV correlation in FMF.

Differential expression of cell-wall-related genes during the formation of tracheary elements in the Zinnia mesophyll cell system

Plants, animals and some fungi undergo processes of cell specialization such that specific groups of cells are adapted to carry out particular functions. One of the more remarkable examples of cellular development in higher plants is the formation of water-conducting cells that are capable of supporting a column of water from the roots to tens of metres in the air for some trees. The Zinnia mesophyll cell system is a remarkable tool with which to study this entire developmental pathway in vitro. We have recently applied an RNA fingerprinting technology, to allow the detection of DNA fragments derived from RNA using cDNA synthesis and subsequent PCR-amplified fragment length polymorphisms (cDNA-AFLP), to systematically characterize hundreds of the genes involved in the process of tracheary element formation. Building hoops of secondary wall material is the key structural event in forming functional tracheary elements and we have identified over 50 partial sequences related to cell walls out of 600 differentially expressed cDNA fragments. The Zinnia system is an engine of gene discovery which is allowing us to identify and characterize candidate genes involved in cell wall biosynthesis and assembly.

Pulmonary nocardiosis: clinical experience in ten cases

BACKGROUND

Pulmonary nocardiosis is an infrequent infection whose incidence seems to be increasing due to a higher degree of clinical suspicion and the increasing number of immunosuppressive factors.

OBJECTIVE

To study the predisposing factors, clinical characteristics, diagnostic procedures, treatment and progress of pulmonary nocardiosis (PN).

METHODS

Review of 10 patients (9 male, 1 female, mean age 61) with PN in a 600-bed teaching hospital, diagnosed from 1992 to 1999.

RESULTS

Associated diseases observed were chronic obstructive pulmonary disease (COPD) in 6 patients, human immunodeficiency virus (HIV) infection in 3 and polymyalgia rheumatica in 1. Four patients had received oral corticotherapy for COPD for over a year (mean dose 13 mg/day of prednisone or equivalent). The main reason for consultation was an increase in dyspnea in the patients with COPD (6/6) and fever in those with HIV (3/3). Mean time between onset of symptoms and diagnosis was 5 weeks. In 8 patients, the infection occurred outside the hospital setting. The infection was restricted to the lung in 9/10; in the remaining case, the central nervous system (CNS) and subcutaneous tissue were affected. Lobar or multilobar consolidation was the most frequent radiographic pattern found (6/10). Sputum culture was positive when performed (8 cases). Diagnosis was made or confirmed by bronchoscopy (bronchoaspirate or protected specimen brush) in 5 patients. Germs isolated were: Nocardia asteroides (8/10), Nocardia farcinica (1/10), Nocardia otitidiscaviarum (1/10). Cotrimoxazole was the most used empirical treatment (6/10). Resolution was achieved in 5 cases. Four subjects died: 1 HIV patient with disseminated nocardiosis, and 3 COPD patients, 2 of whom had received long-term corticotherapy. Illness recurred in only 1 case, due to failure to comply with treatment.

CONCLUSIONS

(1) In our geographical setting Nocardia presents as a subacute or chronic pulmonary infection, mainly outside the hospital. (2) It tends to affect only the lung. (3) Diagnosis requires a high clinical suspicion, and can be made on the basis of a sputum culture. (4) Nocardia tends to attack patients with underlying COPD, or immunodepressed patients treated with glucocorticoids, or patients with HIV infection. (5) Mortality is high in both COPD and HIV patients. (6) In our area, cotrimoxazole seems to be the most commonly prescribed treatment.

Structural and Texture Evolution with Temperature of Layered Double Hydroxides Intercalated with Paramolybdate Anions

Paramolybdate-LDHs with MgAl or ZnAl cations within the layers have been prepared by the ion-exchange method from hydrotalcites with different interlayer anions (OH-, NO3(-), and terephthalate). The samples and the oxides obtained after their calcination were characterized by element chemical analysis, PXRD, FT-Raman spectroscopy, thermal analysis (TG/DTA), N2 adsorption at -196 degrees C, and SEM. The results show that layered solids with hydrotalcite-type structure were obtained in which the interlayer space is occupied by heptamolybdate with a small amount of MoO4(2-) units formed through hydrolysis of the polyanion; both oxomolybdenum species undergo a progressive distortion of the octahedral units from 50 degrees C but are roughly stable up to 250 degrees C as a consequence of the interaction between the polyanion and the brucite-like layers. This distortion is responsible for the observed decrease in the height of the gallery for samples heated in the temperature range, 50-250 degrees C, with respect to the original samples. Rehydration of the calcined solids allows recovering of their original structures and the initial values for the gallery heights. Calcination between 300 and 400 degrees C gives rise to a collapse of the layered structure, and amorphous phases are formed, in which molybdenum is both octahedrally and tetrahedrally coordinated. Crystalline magnesium and zinc molybdates (MgMoO4 and ZnMoO4) are formed at 450 and 600 degrees C, respectively. All solids have some microporosity, which decreases with increasing the calcination temperature.

Dental composites reinforced with hydroxyapatite: mechanical behavior and absorption/elution characteristics

The purpose of this study was to analyze the behavior in water as well as the mechanical and surface properties of experimental composites designed for dental restoration. Studied materials were composed of a visible-light-cured monomer mixture as a matrix (bisphenol-alpha-glycidyl methacrylate with triethyleneglycol dimethacrylate or hydroxyethyl methacrylate) and either micrometric or nanometric hydroxyapatite (HA) particles as a reinforcing filler. The surface of the filler particles was modified by using different coupling agents (citric, hydroxysuccinic, acrylic, or methacrylic acid). The hydrolytic stability of the evaluated materials was studied through elution-in-water and water-uptake tests. Mechanical and surface properties were examined through the results of flexural, hardness, and surface roughness tests. Means and standard deviations were calculated for each variable. Analysis of variance and multiple comparison tests were performed. Materials containing bisphenol-alpha-glycidyl methacrylate:triethyleneglycol dimethacrylate and micrometric-HA coated with citrate, acrylate, or methacrylate displayed the most favorable results. Improvements should be obtained by increasing the total filler amount, and by the introduction of nanometric-HA filler into a micrometric-HA reinforced composite resin system.

Carbon Nanotube Bundles as Molecular Assemblies for the Detection of Polycyclic Aromatic Hydrocarbons: Surface-Enhanced Resonance Raman Spectroscopy and Theoretical Studies

In this work surface-enhanced resonance Raman spectroscopic experiments have demonstrated that metallic single-walled carbon nanotubes can be used as chemical assemblies between the pyrene analyte and the silver colloidal surface. Pyrene has been detected at concentrations lower than 10(-9) M by use of the 514.5 nm excitation laser line. A charge transfer from the surface to the nanotube characterizes the nanotube-silver surface interaction. The pyrene-nanotube interaction occurs through a pi-pi electronic stacking. Extended Hückel calculations based on a simplified molecular model for the analyte/nanotube/surface system support the experimental conclusions. The nanotube-pyrene distance is 3.4 A, and the most probable orientation for pyrene is confirmed to be plane parallel to the nanotube surface. An energy transfer from the silver surface to the nanotube/analyte system is verified.

Induction of notochord cell intercalation behavior and differentiation by progressive signals in the gastrula of Xenopus laevis

We show that notochord-inducing signals are present during Xenopus laevis gastrulation and that they are important for both inducing and organizing cell behavior and differentiation in the notochord. Previous work showed that convergent extension of prospective notochordal and somitic mesoderm occurs by mediolateral cell intercalation to produce a longer, narrower tissue. Mediolateral cell intercalation is driven by bipolar, mediolaterally directed protrusive activity that elongates cells and then pulls them between one another along the mediolateral axis. This cell behavior, and subsequent notochordal cell differentiation, begins anteriorly and spreads posteriorly along the notochordal-somitic boundary, and from this lateral boundary progresses medially towards the center of the notochord field. To examine whether these progressions of cell behaviors and differentiation are induced and organized during gastrulation, we grafted labeled cells from the prospective notochordal, somitic and epidermal regions of the gastrula into the notochordal region and monitored their behavior by low light, fluorescence videomicroscopy. Prospective notochordal, epidermal and somitic cells expressed mediolateral cell intercalation behavior in an anterior-to-posterior and lateral-to-medial order established by the host notochord. Behavioral changes were induced first and most dramatically among cells grafted next to the notochordal-somitic boundary, particularly those in direct contact with the boundary, suggesting that the boundary may provide signals that both induce and organize notochordal cell behaviors. By physically impeding normal convergent extension movements, notochordal cell behaviors and differentiation were restricted to the anteriormost notochordal region and to the lateral notochordal-somitic boundary. These results show that mediolateral cell intercalation behavior and notochordal differentiation can be induced in the gastrula stage, among cells not normally expressing these characteristics, and that these characteristics are induced progressively, most likely by signals emanating from the notochordal-somitic boundary. In addition, they show that morphogenetic movements during gastrulation are necessary for complete notochord formation and that the prospective notochord region is not determined by the onset of gastrulation.

Acute eosinophilic pneumonia due to toxocariasis with bronchoalveolar lavage findings

A previously healthy young man presented with breathlessness, diffuse pulmonary infiltrates on the chest x-ray film, and a high degree of peripheral blood eosinophilia. Analysis of bronchoalveolar lavage (BAL) fluid showed 64 percent eosinophils. A diagnosis of toxocariasis was eventually reached on the basis of a positive enzyme-linked immunosorbent assay (ELISA) for Toxocara canis. The routine performance of the ELISA test for Toxocara in the diagnostic approach to pulmonary infiltration with eosinophilia could reveal an undetermined, sometimes unsuspected, number of cases of adult toxocariasis with pulmonary involvement. A high degree of eosinophilia in the differential cell count of BAL fluid may eventually prove to be a useful clue in favor of such a diagnosis.

Yellow fever vaccine-associated viscerotropic disease and death in Spain

Yellow fever vaccine-associated viscerotropic disease (YEL-AVD) is a recently described severe adverse event after yellow fever vaccination, and some cases have been reported in different countries [Anonymous. Effects of yellow fever and vaccination. Lancet 2001;358(9296):1907-9]. Herein we describe a YEL-AVD case in a young woman, who died after vaccination with 17D-204 strain. Clinical, serological and immunochemical analysis as well as virus detection, quantification, sequence analysis and cytokine release, were performed. Further investigations on yellow fever vaccine adverse events, and carefully analysis of the immune response elicited are important tasks for the future.

Use of a short fragment of the C-terminal E gene for detection and characterization of two new lineages of dengue virus 1 in India

Here we propose the use of a 216-nucleotide fragment located in the carboxyl terminus of the E gene (E-COOH) and a pairwise-based comparison method for genotyping of dengue virus 1 (DENV-1) strains. We have applied this method to the detection and characterization of DENV-1 in serum samples from travelers returning from the tropics. The results obtained with the typing system correlate with the results obtained by comparison of the sequences of the entire E gene of the strains. The approach demonstrates utility in plotting the distribution and circulation of different genotypes of DENV-1 and also suggests the presence of two new clades of Indian strains. The integration of the method with an online database and a typing characterization tool enhances its strength. Additionally, the analysis of the complete E gene of DENV-1 strains suggested the occurrence of a nondescribed recombination event in the China GD23-95 strain. We propose the use of this methodology as a tool for real-time epidemiological surveillance of dengue virus infections and their pathogenesis.

Hydrolytic stability of experimental hydroxyapatite-filled dental composite materials

OBJECTIVES

The purpose of this study was to analyze the behavior in water, related to mechanical properties, of experimental composites for dental restoration.

METHODS

The studied materials were composed of a visible-light-curing monomer mixture (Bis-GMA and TEGDMA or HEMA) and micrometric, nanometric or a mixture of both sizes hydroxyapatite particles as a reinforcing filler. Filler particles were modified with a coupling agent (citric, hydrosuccinic, acrylic or methacrylic acid or silane). The hydrolytic stability of the evaluated materials was studied through total elution and water-uptake tests. Percent net-mass variation was daily monitored and analyzed as a function of time. Mechanical performance was examined through flexural properties and Vickers hardness. Morphological surface changes were observed with scanning electron microscopy. ANOVA statistical analysis was performed (P<0.05).

RESULTS

In general, the use of HEMA instead of TEGDMA did not substantially worsen the composite quality. Dental composites containing only nanometric particles of hydroxyapatite as a filler are unsuitable for clinical performance. Midway-filled composite resins loaded with micro-HAP particles, coated with citric, acrylic or methacrylic acid displayed low percent elution and water-uptake values. Mechanical properties were similar or even superior to those measured for silane treated particles.

SIGNIFICANCE

More research is needed to further improve the interaction of nano-HAP particles with the polymeric matrix, either as a single filler or, preferentially, mixed with micro-HAP, that will allow to increase the total loading of reinforcing filler and, hence, to improve the mechanical properties.

Composite fibrous biomaterials for tissue engineering obtained using a supercritical CO2 antisolvent process

Several techniques have been proposed for producing porous structures or scaffolds for tissue engineering but, as yet, with no optimal solution. With regard to this topic, this paper focuses on the preparation of biocompatible nanometric filler-polymer composites organized in a network of fibers. Titanium dioxide (TiO2) or hydroxyapatite (HAP) nanopowders as the guest particles and poly(lactic acid) (L-PLA) or the blend poly(methylmethacrylate)/poly(epsilon-caprolactone) (PMMA/PCL) as the polymer carrier were selected as model systems for this purpose. A supercritical antisolvent technique was used to produce the composites. In the process developed, the non-soluble particulate filler was suspended in a polymer solution, and both components were sprayed simultaneously into supercritical carbon dioxide (scCO2). Using this technique, polymeric matrices were loaded with approximately 10-20 wt.% of inorganic phase distributed throughout the composite. Two different hybrid materials were prepared: a PMMA/PCL+TiO2 system where either fibers or microparticles were prepared by varying the molecular weight of the used PMMA; and fibers in the case of L-PLA+HAP system. After further post-processing in a three-dimensional network, these nanofibers can potentially be used as scaffolds for tissue engineering.

Lower respiratory tract infections following cardiac arrest and cardiopulmonary resuscitation

All episodes of lower respiratory tract infection that developed among 96 patients surviving for > 24 hours after cardiac arrest were prospectively studied over an 18-month period. Pneumonia developed in 23 (24.0%) of patients after a mean of 7 days (SD, +/- 6.2 days). The development of four superinfections raised the cumulative incidence to 28.1%. Purulent tracheobronchitis was diagnosed in three instances. The causative agent of pneumonia was identified in 18 episodes, three of which were polymicrobial. Gram-positive cocci represented 57.1% of isolates, and Staphylococcus aureus--the most frequently isolated microorganism in this population--accounted for two-thirds of all gram-positive cocci. Pseudomonas aeruginosa was isolated in six episodes, five of which were associated with previous antibiotic use. Nine (39.1%) of the 23 patients in the group with pneumonia died, but only one of these deaths was considered to be directly related to pneumonia. In conclusion, pneumonia is a common complication of patients surviving cardiac arrest, but, with adequate treatment, its influence on outcome is marginal. Gram-positive cocci are the predominant pathogens, although infection with P. aeruginosa should be considered among patients receiving antibiotics.