Analysis of the limited M. tuberculosis accessory genome reveals potential pitfalls of pan-genome analysis approaches

Pan-genome analysis is a fundamental tool for studying bacterial genome evolution; however, the variety of methods used to define and measure the pan-genome poses challenges to the interpretation and reliability of results. To quantify sources of bias and error related to common pan-genome analysis approaches, we evaluated different approaches applied to curated collection of 151 Mycobacterium tuberculosis ( Mtb ) isolates. Mtb is characterized by its clonal evolution, absence of horizontal gene transfer, and limited accessory genome, making it an ideal test case for this study. Using a state-of-the-art graph-genome approach, we found that a majority of the structural variation observed in Mtb originates from rearrangement, deletion, and duplication of redundant nucleotide sequences. In contrast, we found that pan-genome analyses that focus on comparison of coding sequences (at the amino acid level) can yield surprisingly variable results, driven by differences in assembly quality and the softwares used. Upon closer inspection, we found that coding sequence annotation discrepancies were a major contributor to inflated Mtb accessory genome estimates. To address this, we developed panqc, a software that detects annotation discrepancies and collapses nucleotide redundancy in pan-genome estimates. When applied to Mtb and E. coli pan-genomes, panqc exposed distinct biases influenced by the genomic diversity of the population studied. Our findings underscore the need for careful methodological selection and quality control to accurately map the evolutionary dynamics of a bacterial species.

Diverse and abundant phages exploit conjugative plasmids

Phages exert profound evolutionary pressure on bacteria by interacting with receptors on the cell surface to initiate infection. While the majority of phages use chromosomally encoded cell surface structures as receptors, plasmid-dependent phages exploit plasmid-encoded conjugation proteins, making their host range dependent on horizontal transfer of the plasmid. Despite their unique biology and biotechnological significance, only a small number of plasmid-dependent phages have been characterized. Here we systematically search for new plasmid-dependent phages targeting IncP and IncF plasmids using a targeted discovery platform, and find that they are common and abundant in wastewater, and largely unexplored in terms of their genetic diversity. Plasmid-dependent phages are enriched in non-canonical types of phages, and all but one of the 65 phages we isolated were non-tailed, and members of the lipid-containing tectiviruses, ssDNA filamentous phages or ssRNA phages. We show that plasmid-dependent tectiviruses exhibit profound differences in their host range which is associated with variation in the phage holin protein. Despite their relatively high abundance in wastewater, plasmid-dependent tectiviruses are missed by metaviromic analyses, underscoring the continued importance of culture-based phage discovery. Finally, we identify a tailed phage dependent on the IncF plasmid, and find related structural genes in phages that use the orthogonal type 4 pilus as a receptor, highlighting the evolutionarily promiscuous use of these distinct contractile structures by multiple groups of phages. Taken together, these results indicate plasmid-dependent phages play an under-appreciated evolutionary role in constraining horizontal gene transfer via conjugative plasmids.

Diverse and abundant phages exploit conjugative plasmids

Phages exert profound evolutionary pressure on bacteria by interacting with receptors on the cell surface to initiate infection. While the majority of phages use chromosomally-encoded cell surface structures as receptors, plasmid-dependent phages exploit plasmid-encoded conjugation proteins, making their host range dependent on horizontal transfer of the plasmid. Despite their unique biology and biotechnological significance, only a small number of plasmid-dependent phages have been characterized. Here we systematically search for new plasmid-dependent phages targeting IncP and IncF plasmids using a targeted discovery platform, and find that they are common and abundant in wastewater, and largely unexplored in terms of their genetic diversity. Plasmid-dependent phages are enriched in non-canonical types of phages, and all but one of the 64 phages we isolated were non-tailed, and members of the lipid-containing tectiviruses, ssDNA filamentous phages or ssRNA phages. We show that plasmid-dependent tectiviruses exhibit profound differences in their host range which is associated with variation in the phage holin protein. Despite their relatively high abundance in wastewater, plasmid-dependent tectiviruses are missed by metaviromic analyses, underscoring the continued importance of culture-based phage discovery. Finally, we identify a tailed phage dependent on the IncF plasmid, and find related structural genes in phages that use the orthogonal type 4 pilus as a receptor, highlighting the promiscuous use of these distinct contractile structures by multiple groups of phages. Taken together, these results indicate plasmid-dependent phages play an under-appreciated evolutionary role in constraining horizontal gene transfer via conjugative plasmids.

A Weight of Evidence approach to support the assessment of the quality of Manila clam farming sites in a coastal lagoon

Aquaculture productivity in coastal lagoons is endangered by a complex interplay of anthropogenic and environmental factors, amplified by the effects of climate change in these sensitive areas. To reach a more comprehensive assessment of farming sites quality, a quantitative Weight of Evidence approach (QWoE) is applied for the first time to data collected at four Manila clam (R. philippinarum) farming sites in the Venice lagoon (Italy). This included sediment quality, chemical bioaccumulation, and biological responses. Results revealed a greater hazard for sites closer to the open sea. In these areas, the combination of sediment characteristics and a higher frequency of salinity and temperature stress could explain the alterations measured at a transcriptional and biomarker level. The findings demonstrate that a QWoE approach that integrates multiple sources of evidence should also include physicochemical conditions in order to better understand the impacts of human activities and other stressors on clam aquaculture productivity.

Full-length transcript alterations in human bronchial epithelial cells with U2AF1 S34F mutations

U2AF1 is one of the most recurrently mutated splicing factors in lung adenocarcinoma and has been shown to cause transcriptome-wide pre-mRNA splicing alterations; however, the full-length altered mRNA isoforms associated with the mutation are largely unknown. To better understand the impact U2AF1 has on full-length isoform fate and function, we conducted high-throughput long-read cDNA sequencing from isogenic human bronchial epithelial cells with and without a U2AF1 S34F mutation. We identified 49,366 multi-exon transcript isoforms, more than half of which did not match GENCODE or short-read-assembled isoforms. We found 198 transcript isoforms with significant expression and usage changes relative to WT, only 68% of which were assembled by short reads. Expression of isoforms from immune-related genes is largely down-regulated in mutant cells and without observed splicing changes. Finally, we reveal that isoforms likely targeted by nonsense-mediated decay are down-regulated in U2AF1 S34F cells, suggesting that isoform changes may alter the translational output of those affected genes. Altogether, our work provides a resource of full-length isoforms associated with U2AF1 S34F in lung cells.

Analysis of genome-wide mutational dependence in naturally evolving Mycobacterium tuberculosis populations

Pathogenic micro-organisms are in a perpetual struggle for survival in changing host environments, where host pressures necessitate changes in pathogen virulence, antibiotic resistance, or transmissibility. The genetic basis of phenotypic adaptation by pathogens is difficult to study in vivo. In this work, we develop a phylogenetic method to detect genetic dependencies that promote pathogen adaptation using 31,428 in vivo sampled Mycobacterium tuberculosis genomes, a globally prevalent bacterial pathogen with increasing levels of antibiotic resistance. We find that dependencies between mutations are enriched in antigenic and antibiotic resistance functions, and discover 23 mutations that potentiate the development of antibiotic resistance. Between 11% and 92% of resistant strains harbor a dependent mutation acquired after a resistance-conferring variant. We demonstrate the pervasiveness of genetic dependency in adaptation of naturally evolving populations and the utility of the proposed computational approach. Data and code available at: https://github.com/farhat-lab/DependentMutations.

Effects of environmental concentrations of the fragrance amyl salicylate on the mediterranean mussel Mytilus galloprovincialis

Amyl salicylate (AS) is a fragrance massively used as a personal care product and following the discharged in wastewaters may end up in the aquatic environment representing a potential threat for the ecosystem and living organisms. AS was recently detected in water of the Venice Lagoon, a vulnerable area continuously subjected to the income of anthropogenic chemicals. The lagoon is a relevant area for mollusc farming, including the Mediterranean mussels (Mytilus galloprovincialis) having an important economic and ecological role. Despite high levels of AS occurred in water of the Lagoon of Venice, no studies investigated the possible consequences of AS exposures on species inhabiting this ecosystem to date. For the first time, we applied a multidisciplinary approach to investigate the potential effects of the fragrance AS on Mediterranean mussels. To reach such a goal, bioaccumulation, cellular, biochemical, and molecular analyses (RNA-seq and microbiota characterization) were measured in mussels treated for 7 and 14 days with different AS Venice lagoon environmental levels (0.1 and 0.5 μg L^-1). Despite chemical investigations suggested low AS bioaccumulation capability, cellular and molecular analyses highlighted the disruption of several key cellular processes after the prolonged exposures to the high AS concentration. Among them, potential immunotoxicity and changes in transcriptional regulation of pathways involved in energy metabolism, stress response, apoptosis and cell death regulations have been observed. Conversely, exposure to the low AS concentration demonstrated weak transcriptional changes and transient increased representation of opportunistic pathogens, as Arcobacter genus and Vibrio aestuarianus. Summarizing, this study provides the first overview on the effects of AS on one of the most widely farmed mollusk species.

The effects of glyphosate and AMPA on the mediterranean mussel Mytilus galloprovincialis and its microbiota

Glyphosate, the most widely used herbicide worldwide, targets the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) enzyme in the shikimate pathway found in plants and some microorganisms. While the potential for glyphosate to induce a broad range of biological effects in exposed organisms has been demonstrated, the global molecular mechanisms of toxicity and potential effects in bacterial symbionts remain unclear, in particular for ecologically important marine species such as bivalve molluscs. Here, the effects of glyphosate (GLY), its degradation product aminomethylphosphonic acid (AMPA), and a mixture of both (MIX) on the mussel M. galloprovincialis were assessed in a controlled experiment. For the first time, next generation sequencing (RNA-seq and 16S rRNA amplicon sequencing) was used to evaluate such effects at the molecular level in both the host and its respective microbiota. The results suggest that the variable capacity of bacterial species to proliferate in the presence of these compounds and the impairment of host physiological homeostasis due to AMPA and GLY toxicity may cause significant perturbations to the digestive gland microbiota, as well as elicit the spread of potential opportunistic pathogens such as Vibrio spp.. The consequent host-immune system activation identified at the molecular and cellular level could be aimed at controlling changes occurring in the composition of symbiotic microbial communities. Overall, our data raise further concerns about the potential adverse effects of glyphosate and AMPA in marine species, suggesting that both the effects of direct toxicity and the ensuing changes occurring in the host-microbial community must be taken into consideration to determine the overall ecotoxicological hazard of these compounds.

Pan-cancer analysis of whole genomes

Cancer is driven by genetic change, and the advent of massively parallel sequencing has enabled systematic documentation of this variation at the whole-genome scale1-3. Here we report the integrative analysis of 2,658 whole-cancer genomes and their matching normal tissues across 38 tumour types from the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA). We describe the generation of the PCAWG resource, facilitated by international data sharing using compute clouds. On average, cancer genomes contained 4-5 driver mutations when combining coding and non-coding genomic elements; however, in around 5% of cases no drivers were identified, suggesting that cancer driver discovery is not yet complete. Chromothripsis, in which many clustered structural variants arise in a single catastrophic event, is frequently an early event in tumour evolution; in acral melanoma, for example, these events precede most somatic point mutations and affect several cancer-associated genes simultaneously. Cancers with abnormal telomere maintenance often originate from tissues with low replicative activity and show several mechanisms of preventing telomere attrition to critical levels. Common and rare germline variants affect patterns of somatic mutation, including point mutations, structural variants and somatic retrotransposition. A collection of papers from the PCAWG Consortium describes non-coding mutations that drive cancer beyond those in the TERT promoter4; identifies new signatures of mutational processes that cause base substitutions, small insertions and deletions and structural variation5,6; analyses timings and patterns of tumour evolution7; describes the diverse transcriptional consequences of somatic mutation on splicing, expression levels, fusion genes and promoter activity8,9; and evaluates a range of more-specialized features of cancer genomes8,10-18.

Genomic basis for RNA alterations in cancer

Transcript alterations often result from somatic changes in cancer genomes1. Various forms of RNA alterations have been described in cancer, including overexpression2, altered splicing3 and gene fusions4; however, it is difficult to attribute these to underlying genomic changes owing to heterogeneity among patients and tumour types, and the relatively small cohorts of patients for whom samples have been analysed by both transcriptome and whole-genome sequencing. Here we present, to our knowledge, the most comprehensive catalogue of cancer-associated gene alterations to date, obtained by characterizing tumour transcriptomes from 1,188 donors of the Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium of the International Cancer Genome Consortium (ICGC) and The Cancer Genome Atlas (TCGA)5. Using matched whole-genome sequencing data, we associated several categories of RNA alterations with germline and somatic DNA alterations, and identified probable genetic mechanisms. Somatic copy-number alterations were the major drivers of variations in total gene and allele-specific expression. We identified 649 associations of somatic single-nucleotide variants with gene expression in cis, of which 68.4% involved associations with flanking non-coding regions of the gene. We found 1,900 splicing alterations associated with somatic mutations, including the formation of exons within introns in proximity to Alu elements. In addition, 82% of gene fusions were associated with structural variants, including 75 of a new class, termed 'bridged' fusions, in which a third genomic location bridges two genes. We observed transcriptomic alteration signatures that differ between cancer types and have associations with variations in DNA mutational signatures. This compendium of RNA alterations in the genomic context provides a rich resource for identifying genes and mechanisms that are functionally implicated in cancer.

Ecotoxicological effects of the herbicide glyphosate in non-target aquatic species: Transcriptional responses in the mussel Mytilus galloprovincialis

Glyphosate has been the most widely used herbicide worldwide over the last three decades, raising increasing concerns for its potential impacts on environmental and human health. Recent studies revealed that glyphosate occurs in soil, surface water, and groundwater, and residues are found at all levels of the food chain, such as drinking water, plants, animals, and even in humans. While research has demonstrated that glyphosate can induce a broad range of biological effects in exposed organisms, the global molecular mechanisms of action still need to be elucidated, in particular for marine species. In this study, we characterized for the first time the molecular mechanisms of action of glyphosate in a marine bivalve species after exposure to environmentally realistic concentrations. To reach such a goal, Mediterranean mussels Mytilus galloprovincialis, an ecologically and economically relevant species, were exposed for 21 days to 10, 100, and 1000 μg/L and digestive gland transcriptional profiles were investigated through RNA-seq. Differential expression analysis identified a total of 111, 124, and 211 differentially regulated transcripts at glyphosate concentrations of 10, 100, and 1000 μg/L, respectively. Five genes were found consistently differentially expressed at all investigated concentrations, including SERP2, which plays a role in the protection of unfolded target proteins against degradation, the antiapoptotic protein GIMAP5, and MTMR14, which is involved in macroautophagy. Functional analysis of differentially expressed genes reveals the disruption of several key biological processes, such as energy metabolism and Ca2+ homeostasis, cell signalling, and endoplasmic reticulum stress response. Together, the results obtained suggest that the presence of glyphosate in the marine ecosystem should raise particular concern because of its significant effects even at the lowest concentration.

Clam bioaccumulation of Alkylphenols and Polyciclic aromatic hydrocarbons in the Venice lagoon under different pressures

Biota-Sediment Accumulation Factors (BSAFs) of nonylphenols (NPs) and polycyclic aromatic hydrocarbons (PAHs) in Ruditapes philippinarum from the Venice Lagoon (Italy) were determined with the aim to verify whether the routine biomonitoring studies are reliable in contaminated sites. Clams and sediments were collected in field campaigns (October 2003 to June 2004) in three sites of the Venice Lagoon. Results showed that Marghera and Campalto sediments were more contaminated by NPs and PAHs than Poveglia. Different trends were observed in the contamination of clams with the highest BSAFs found at Poveglia. BSAF trend appeared to be inversely related to the contaminant pressure on the sites. These results suggest that clam bioaccumulation is not always representative of the chemical pressure on aquatic biota. The direct correlation between sediment and biota concentrations in contaminated sites can be lost as a function of the site-specific conditions such as sediment toxicity and food availability.

Does seawater acidification affect survival, growth and shell integrity in bivalve juveniles?

Anthropogenic emissions of carbon dioxide are leading to decreases in pH and changes in the carbonate chemistry of seawater. Ocean acidification may negatively affect the ability of marine organisms to produce calcareous structures while also influencing their physiological responses and growth. The aim of this study was to evaluate the effects of reduced pH on the survival, growth and shell integrity of juveniles of two marine bivalves from the Northern Adriatic sea: the Mediterranean mussel Mytilus galloprovincialis and the striped venus clam Chamelea gallina. An outdoor flow-through plant was set up and two pH levels (natural seawater pH as a control, pH 7.4 as the treatment) were tested in long-term experiments. Mortality was low throughout the first experiment for both mussels and clams, but a significant increase, which was sensibly higher in clams, was observed at the end of the experiment (6 months). Significant decreases in the live weight (-26%) and, surprisingly, in the shell length (-5%) were observed in treated clams, but not in mussels. In the controls of both species, no shell damage was ever recorded; in the treated mussels and clams, damage proceeded via different modes and to different extents. The severity of shell injuries was maximal in the mussels after just 3 months of exposure to a reduced pH, whereas it progressively increased in clams until the end of the experiment. In shells of both species, the damaged area increased throughout the experiment, peaking at 35% in mussels and 11% in clams. The shell thickness of the treated and control animals significantly decreased after 3 months in clams and after 6 months in mussels. In the second experiment (3 months), only juvenile mussels were exposed to a reduced pH. After 3 months, the mussels at a natural pH level or pH 7.4 did not differ in their survival, shell length or live weight. Conversely, shell damage was clearly visible in the treated mussels from the 1st month onward. Monitoring the chemistry of seawater carbonates always showed aragonite undersaturation at 7.4 pH, whereas calcite undersaturation occurred in only 37% of the measurements. The present study highlighted the contrasting effects of acidification in two bivalve species living in the same region, although not exactly in the same habitat.

First cytochemical study of haemocytes from the crab Carcinus aestuarii (Crustacea, Decapoda)

For the first time, a morphological study of haemocytes from the crab Carcinus aestuarii was carried out by means of light microscopy and differing cytochemical assays. Analysis of haemocyte size frequency distribution (performed by means of a Coulter Counter) revealed the presence of two distinct haemocyte fractions in C. aestuarii haemolymph, depending on cell size. The first fraction was of about 3–5 µm in diameter and 30–50 fL in volume, the second was of about 6–12 µm in diameter and over 200 fL in volume. Mean cell diameter and volume were 8.20±1.7 µm and 272.30±143.5 fL, respectively. Haemocytes observed under light microscope were distinguished in three cell types: granulocytes (28%; 11.94±1.43 µm in diameter) with evident cytoplasmic granules, semigranulocytes (27%; 12.38±1.76 µm in diameter) with less granules than granulocytes, and hyalinocytes (44%; 7.88±1.6 µm in diameter) without granules. In addition, a peculiar cell type was occasionally found (about 1%): it was 25–30 µm in diameter and had a great vacuole and a peripheral cytoplasm with granules. Granulocyte and semigranulocyte granules stained in vivo with Neutral Red, indicating that they were lysosomes. Giemsa’s dye confirmed that granulocytes and semigranulocytes were larger than hyalinocytes. Pappenheim’s panoptical staining and Ehrlich’s triacid mixture allowed to distinguish granule-containing cells (including semigranulocytes) in acidophils (64%), basophils (35%) and neutrophils (1%). Hyalinocytes showed always a basophilic cytoplasm. Haemocytes were positive to the PAS reaction for carbohydrates, even if cytoplasm carbohydrate distribution varied among cell types. Lastly, lipids were found on cell membrane and in cytoplasm of all haemocyte types in the form of black spots produced after Sudan Black B staining. The morphological characterisation of C. aestuarii haemocytes by light microscopy was necessary before performing both ultrastructural and functional studies of circulating cells.

Investigation of EROD, CYP1A immunopositive proteins and SOD in haemocytes of Chamelea gallina and their role in response to B[a]P

CYP1A sub-family represents the main form of cytochrome P450 involved in benzo[a]pyrene (B[a]P) detoxification, but there are no clear evidences about its presence in invertebrates. 7-Ethoxy resorufin O-deethylase (EROD) activity is strictly related to CYP1A presence, at the same time P450-dependent oxidative metabolism leads to reactive oxygen species (ROS) production, thought to be an important mechanism of pollutant-mediated toxicity in aquatic organisms. Superoxide dismutases (SODs), EROD and CYP1A activities and/or expressions were detected in haemocytes of pooled clams (Chamelea gallina) and cell-free haemolymph after 24 h, 7 and 12 days of exposure to 0.5 mg/L of B[a]P. After 24 h, B[a]P content was maximum in whole tissues. A 61 kDa band was recognized in haemocytes and cell-free haemolymph by polyclonal anti-fish CYP1A, while 53.5 and 63.8 kDa CYP1A immunopositive proteins were discriminate without differences of expression. Differently, EROD, MnSOD activity/expression and ECSOD expression decreased in haemocytes and haemolymph. C. gallina immune system presents an interesting response dose/time exposure of B[a]P and the 7 days condition highlights the major effects of xenobiotic action. The identification of basal EROD levels supports the possible presence of the CYP1A, never identified in C. gallina and more specifically never isolated in immune cells, as confirmed by CYP1A-immunopositive proteins identification.

Uptake and elimination of 4-nonylphenol by the clam Tapes philippinarum

The present study is the first dealing with the accumulation and elimination of 4-nonylphenol (NP) by the Manila clam, Tapes philippinarum. Specimens of T. philippinarum were exposed to NP-spiked seawater, and the NP contents in whole soft tissue, gills, digestive gland, and haemolymph were measured. Actual NP concentrations in seawater and microalgae (Isochrysis galbana) used for feeding were also determined, and the algal bioconcentration factor (BCF) value (640 ml/g) was calculated. Volatilisation was the main cause of dissipation of NP from experimental tanks, attaining up to 78% of the NP added. NP accumulated by algae used for feeding was negligible with respect to the total added NP, and we concluded that in our experiments, clams accumulated NP mainly from water and not food intake. Accumulation followed a two-compartment, first-order rate coefficient model, with an uptake rate coefficient of 13.8 +/- 0.6 mL g(-1)h(-1)(fresh weight [fw]) and an elimination coefficient of 0.0070 +/- 0.0005 h(-1). Ninety percent of the steady state was reached after 14 days of exposure, and the BCF value at the steady state was 1958 +/- 158 mL g(-1) fw (1.8 +/- 0.2 x 10(5) based on lipid weight). Slightly less than 50% of NP bioaccumulated through water was allocated into the gills, whereas the rest was found in the digestive gland. In the first 8 hours, clams eliminated 51% of the NP accumulated, and only 2% of the NP accumulated was detected in the clams at the end of the elimination phase (day 14). Two-compartment first-order decay model described the elimination of the accumulated NP by considering the clam as two compartments each with a different elimination rate. The sudden elimination of NP in the initial hours can be attributed to the elimination of NP accumulated into the gills and readily available for excretion (k ( e ) = 0.30 +/- 0.07 h(-1)). The slower step of the elimination process should be the mobilisation of NP accumulated in internal organs, which must be carried into the haemolymph for excretion (k(e) = 0.0091 +/- 0.0002 h(-1)). Because T. philippinarum has been demonstrated to accumulate NP dissolved in water, high NP levels can be hypothesised in clams from highly contaminated environments. This research was performed according to all national and international guidelines for animal welfare.

Field validation of autometallographical black silver deposit (BSD) extent in three bivalve species from the Lagoon of Venice, Italy (Mytilus galloprovincialis, Tapes philippinarum, Scapharca inaequivalvis) for metal bioavailability assessment

The autometallographic approach was applied to three filter-feeder bivalves from differently polluted sites of the Lagoon of Venice. The area density (AD) values of black silver deposits (BSDs) were therefore seasonally quantified by image analysis in digestive cell lysosomes. Sediments were characterised in terms of grain size, organic content and metal concentrations (Cd, Cu, Ni, Pb, Zn). The physiological status of the bivalves was also evaluated by applying the "survival in air" test as a generic stress index. Chemical results showed that Zn contributed to the total metal load for more than 60% in sediments and for 85%-94% in mussel and clam digestive glands, respectively (data processed from published results obtained on the same samples). Regression analyses between extent of BSDs and both total metal and Zn concentrations in digestive gland followed a linear pattern in mussels and clams, but not in arks. Similarly, in mussels and clams only, BSD amount was significantly correlated with total metal concentrations in sediments according to a logarithmic model. Consequently, results obtained from autometallography can discriminate sites on the basis of their metal pollution levels, like chemical analyses on both sediments and digestive glands, evaluations being supported by the results of the physiological stress index. As a conclusion, it is suggested that autometallography in bivalves may provide overall estimates of metal fractions moving from sediments towards organisms through the ingestion of metal-enriched particles. Future work is needed to define the bioaccumulation model in arks and to clarify their possible use as metal biomonitors.

Effects of copper and cadmium exposure on functional responses of hemocytes in the clam, Tapes philippinarum

The effects of Cu and Cd on functional responses of hemocytes in Tapes philippinarum, a Veneridae clam widespread in the lagoon of Venice, were evaluated. Bivalves were exposed for 7 days to various concentrations of CuCl(2) x 2H(2)O (0, 10, 60, and 110 microg/L) and CdCl(2) x H(2)O (0, 150, 300, and 450 microg/L). Hemocytes were collected from exposed clams, and the effects of Cu and Cd on phagocytosis, Neutral Red retention capacity, superoxide dismutase, and cytochrome oxidase activities were investigated. Hemocytes from animals exposed to Cu showed a significant decrease in phagocytic activity, whereas no inhibition was observed in cells from Cd-exposed animals. Diffusion of Neutral Red into the cytosol, an index of lysosomal membrane alteration, was enhanced by high concentrations of both metals. Different results in biochemical parameters were observed. Exposure to 60 and 110 microg Cu/L caused a significant reduction in hemocyte superoxide dismutase activity, whereas no changes resulted after Cd exposure. Increased cytochrome oxidase activity was observed in hemocytes from mollusks exposed to 60 microg Cu/L and 300 microg Cd/L; no significant differences were found in cells from bivalves exposed to 110 microg Cu/L and 450 microg Cd/L. These results suggest a relationship between heavy metal exposure and alterations in functional responses of hemocytes in T. philippinarum and indicate that the type of observed effects vary with the nature and concentration of heavy metals. Moreover, the data obtained in the analyzed clam support the possibility of using it as sentinel organism in biomonitoring studies, even if used biomarkers will be further evaluated in field conditions.

Haemocytes of the clam Tapes philippinarum (Adams & Reeve, 1850): morphofunctional characterisation

Tapes philippinarum is a bivalve mollusc of the Pacific Ocean, successfully imported for human consumption into the northern Adriatic Sea (Europe). For better knowledge of its considerable adaptive ability in comparison with similar autochthonous species, a morpho-functional characterisation of its haemocytes was carried out with the establishment of short-term cell cultures (60 min at 25 degrees C). Various methods of cytochemical staining identified four cell types in the haemolymph: granulocytes (48.05% +/- 1.43), hyalinocytes (32.18% +/- 0.99), haemoblasts (18.97% +/- 0.63) and serous cells (0.8% +/- 0.19). The granulocytes, possessing cytoplasmic granules with differing dye affinity, included basophils, neutrophils and acidophils. Such granules stained vitally with Neutral Red, and correspond to lysosomes. Hydrolytic and oxidative enzymes were mainly detectable after stimulation in the presence of yeast cells. Both granulocytes and hyalinocytes were positive for alkaline phosphatase, non-specific esterase, peroxidase, and cytochrome C oxidase, whereas only granulocytes were positive for beta-glucuronidase, acid esterase, and arylsulphatase. Both cell types were competent phagocytes towards yeast and plasma had an opsonising effect. Moreover, the respiratory burst accompanied phagocytosis with superoxide anion production, recognisable through cytoplasmic deposits of formazan after treatment with nitro blue tetrazolium. Haemoblasts were small undifferentiated cells which, due to their morphology and positivity to the anti-CD34 antibody, show the typical features of stem cells. Serous cells, probably arising from Keber's gland and belonging to another differentiation pathway, contained non-sulphate acid mucopolysaccharides and play an important role in early defence mechanisms, taking part in the formation of clots.

Prevention of nosocomial bloodstream infections: effectiveness of antimicrobial-impregnated and heparin-bonded central venous catheters

OBJECTIVES

To examine the effectiveness of antimicrobial-impregnated and heparin-bonded catheters relative to standard central venous catheters in lessening catheter-related bloodstream infections.

DATA SOURCES

Articles were identified by computer-assisted searching.

STUDY SELECTION

Studies were eliminated from further consideration if they did not contain original data relevant to lessening catheter-related bloodstream infections, were nonrandomized or uncontrolled, described subjects <17 yrs of age, or used animal subjects.

DATA ABSTRACTION

From each eligible article, we abstracted the following: a) citation; b) type of control; c) study setting; d) type of experimental catheter; e) catheter-specific complications; f) total numbers of patients and catheters; g) number of experimental catheters used that resulted in a catheter-related bloodstream infection; h) number of control catheters used that resulted in a catheter-related bloodstream infection; i) number of experimental catheters used without catheter-related bloodstream infections; and j) number of control catheters used without infections. We also recorded the duration of catheter use and the types of microbes cultured in association with the catheters and with catheter-related bloodstream infections.

DATA SYNTHESIS

Eleven eligible studies were identified. Using meta-analysis, we showed that antimicrobial-impregnated and heparin-bonded central venous catheters significantly decreased catheter-related bloodstream infections by 2.32% (95% confidence interval, 1.04% to 3.61%).

CONCLUSIONS

The modest additional cost for the use of these catheters relative to the considerable cost of treating even a single bloodstream infection makes their use cost-effective.

Embryotoxicity of butyltin compounds to the sea urchin Paracentrotus lividus

Tributyltin (TBT) has been widely employed in marine anti-fouling paints as a biocide, although it represents a serious risk, particularly in estuarine and coastal water/sediment ecosystems. In this study, the embryotoxic effects of TBT and its degradation products, dibutyltin (DBT) and monobutyltin (MBT), were analyzed during the development of the sea urchin Paracentrotus lividus from post-fertilization to the pluteus stage, to better clarify ecotoxicological impact. The embryotoxicity of butyltins is concentration-dependent and increases proportionally with number of butyl groups. Significant growth reduction was observed at TBT concentrations as low as 0.01 microgram l-1; 1 microgram l-1 was the maximum concentration allowing embryos to reach the pluteus stage at 48 h post-fertilization. Development was blocked at the morula or blastula stage with higher TBT concentrations. DBT and MBT are less toxic: slowed development and a decrease in pluteus size occurred at 10 micrograms l-1 DBT and 0.5 mg l-1 MBT. Effects on both skeletal deposition and blocked embryonic development are suggested to be due to the interference of organotin compounds with intracellular calcium homeostasis.

Adverse behavioral and sexual factors in chronic vulvar disease

OBJECTIVE

We investigated the prevalence of adverse sexual, personal hygiene, and self-treatment behavior among women with chronic benign vulvar and vaginal disorders.

STUDY DESIGN

This study was carried out by means of a scientific clinical audit producing actuarial data by way of a semistructured questionnaire. Subjects consisted of a sample of 530 cases treated at a specialist clinic for vulvar diseases. In addition to clinical and laboratory investigations, the patients were interviewed by the clinic's psychologist, who used a structured interview schedule developed specifically for the study. Descriptive analysis and analysis of variance were used to investigate data.

RESULTS

Most patients remained sexually active in spite of arousal failure and discomfort and engaged in unlubricated and often painful sexual intercourse. Most women engaged in potentially harmful genital hygiene and self-treatment behavior. Adverse self-treatment practices but not adverse genital hygiene practices were associated with greater symptom duration.

CONCLUSIONS

Adverse practices should be addressed during the management of cases of chronic vulvar disease.

Cost-effectiveness of a post-exposure HIV chemoprophylaxis program for blood exposures in health care workers

We performed a cost-effectiveness analysis of a post-exposure chemoprophylaxis program for health care workers who sustained exposures to blood. We analyzed a program of (1) treatment with zidovudine alone versus no treatment and (2) treatment with three-drug therapy versus no treatment. Assuming that 35% of exposures were to HIV-positive sources, the zidovudine regimen prevented 53 HIV seroconversions per 100,000 exposures, at a societal cost of $2.0 million per case of HIV prevented. The cost per quality-adjusted life year saved was $175,222. A three-drug chemoprophylactic therapy program (postulating 100% effectiveness and 35% source HIV positivity), prevented 66 seroconversions per 100,000 exposures, at a cost of $2.1 million per case of HIV prevented and $190,392 per quality-adjusted life year saved. Treating sources known to be HIV-positive and treating severe exposures were the most cost-effective strategies.

Immunotoxic effects of organotin compounds in Tapes philippinarum

One of the most harmful groups of coastal pollutants is the organotin compounds (OTCs) which have severe effects on both aquatic organisms and mammals including humans. The immunotoxic effects of OTCs were studied in the cultivated clam Tapes philippinarum by determining the immunosuppressant role on in vitro yeast phagocytosis at low doses (0.01, 0.05, 0.1 microM). The phagocytic index was significantly reduced in an irreversible non-lethal manner depending on concentration and lipophilic affinity. The order of inhibition was TBT > or = DBT > MBT for butyltins and TPTC > TPTA > or = TPTH for triphenyltins.

Dyspareunia and vulvar disease

OBJECTIVE

To determine the presence and frequency of contributing factors in functional dyspareunia and if these factors differ between patients with an epithelial disorder and those with apparently healthy genitalia.

STUDY DESIGN

A psychologist assessed patients reporting dyspareunia at a vulvar diseases clinic by using a structured interview questionnaire, the Beck Depression Inventory, and the Spielberger State/Trait Anxiety Inventory. The questionnaire topics included sexual behavior, stresses and coping. Data were divided into two groups based on patients' functional diagnosis or epithelial disorder.

RESULTS

Both groups recorded high levels of trauma-producing sexual behavior. Such behavior included unlubricated, unaroused and undesired sex. High levels of psychological and coping difficulties were also seen. Differences between the groups were seen in undesired sex, capacity to cope, stress factors coincidental with symptom onset and distress at the time of interview.

CONCLUSION

Due to the high frequency of factors contributing to dyspareunia, such factors should be address regardless of the diagnosis. In all such patients it is recommended that a sexual and stress history be taken and counseling be considered.

Low-dose methotrexate spares steroid usage in steroid-dependent asthmatic patients: a meta-analysis

STUDY OBJECTIVES

To determine if treatment with low-dose methotrexate spares oral steroids in adult, steroid-dependent, asthmatic patients.

DESIGN

Articles identified by computer search were excluded if they (1) did not contain original data relating to the primary question, (2) had no controls, or (3) described subjects younger than 18 years of age.

MEASUREMENTS

From each article, the following was abstracted: reference citation; type of control; whether study incorporated a run-in period in which the baseline level of prednisone was reduced to the lowest possible dose; dosage and length of methotrexate therapy; baseline dosage; and type of steroid. Also, the following was determined during both placebo and methotrexate arms of each study: steroid dosage, FEV1, serious side effects, and alteration in level of serum aspartate aminotransferase.

RESULTS

Eleven eligible studies were identified. Methotrexate treatment resulted in a decrease in prednisone or prednisolone usage by an average of 4.37 mg/d or 23.7% of the initial dosage. The summary effect size in standard deviations (SDs) was -0.53 (95% confidence interval=-0.29 to -0.77). Subgroup analysis showed that patients treated with prolonged (6-month) therapy with methotrexate, those with low long-term usage of steroids (< or = 20 mg/d), and those whose study design incorporated a run-in period, tended to have the greatest steroid-sparing effects with methotrexate.

CONCLUSIONS

Low-dose methotrexate has a significant steroid-sparing effect in steroid-dependent asthmatic patients. The greatest effect was evident in patients in whom an effort was made to reduce baseline steroid dosage and in whom methotrexate was used for 24 weeks.

Hepatitis C virus genotypes in northern Italy: clinical and virological features

We analyzed the characteristics of subjects from the same area who were infected with hepatitis C virus genotypes 1 through 4 and subtypes 1a and 1b. Our data are consistent with a rapid evolution in the epidemiology of HCV genotypes and argue against different pathogenic potentials for genotypes 1b and 2.

Detection of HIV-1 proviral sequences in lymphocytes using a qualitative polymerase chain reaction assay

The performance and clinical relevance of a qualitative PCR-based assay for the detection of HIV-1 DNA sequences in peripheral blood mononuclear cells (PBMCs) was evaluated by two different laboratories. Four hundred and one samples were obtained from 397 individuals from different risk populations. All blood donors tested had negative results; positive signals were obtained from all infected patients. HIV-1 DNA was detected in 3 of 17 infants born to seropositive mothers; Western blot indeterminate blood donors and exposed health-care workers had negative results. Our results demonstrate that this PCR assay provides both sensitive and specific results and is suitable for testing large numbers of samples and for rapid identification of HIV-1 infection.

Clinical significance of serum hepatitis C virus (HCV) RNA as marker of HCV infection

We have evaluated the clinical significance of hepatitis C virus (HCV) RNA determination by analyzing a group of 221 hospitalized patients with abnormal liver function tests. Serum HCV RNA was detected by "nested" PCR amplification followed by nonisotopic hybridization. Of the 200 (90.5%) patients with anti-HCV-positive enzyme-linked immunosorbent assay results, 152 (76%) were RIBA reactive, 47 (23.5%) had indeterminate results, and 1 (0.5%) was nonreactive. Of the 180 (90%) patients positive for anti-HCV and HCV RNA, 138 (76.7%) were RIBA reactive and 42 (23.3%) were RIBA indeterminate. The pattern of RIBA reactivity did not correlate with the presence of HCV RNA. Elevated alanine aminotransferase levels were associated neither with the presence of viremia nor with the RIBA pattern. Histological findings consistent with non-A non-B hepatitis correlated with the presence of HCV RNA but not with the RIBA pattern. HCV RNA was detected in 11 of 21 (52.4%) anti-HCV-negative patients. These 11 patients were either immunosuppressed or in the prodromic phase of acute hepatitis C. Circulating HCV RNA can therefore be described as being predictive of virus-induced liver damage in anti-HCV-positive patients and may be useful in the diagnosis of HCV infection in anti-HCV-negative immunosuppressed patients or in those with early acute infection.

Distribution of viral genotypes in Italy determined by hepatitis C virus typing by DNA immunoassay

The distribution of hepatitis C virus (HCV) genotypes in Italy was investigated by PCR amplification of the E1 region and hybridization with type I- and type II-specific nonisotopic probes. Positive PCR results were obtained for 65 of 72 patients (90.3%). Type I was detected in 13 of 72 patients (18%), type II was detected in 39 patients (54.2%), and a mixed type I-type II infection was detected in 7 patients (9.7%). Six amplification products not classified by this method shared a low level of homology with HCV types I and II. HCV type I was significantly associated with human immunodeficiency virus, whereas HCV type II was detected in older subjects who were negative for human immunodeficiency virus markers. These results indicate different epidemiological distributions of HCV types I and II in Italy.

HCV-RNA detection in ultrasound-guided fine needle biopsies of liver nodules and surrounding tissue

HCV-RNA was examined in serum and liver tissue obtained from 8 hepatitis B surface antigen (HBsAg) negative patients with liver nodules ranging in size from 2 to 11 cm. Histological examination of ultrasound-guided fine needle biopsies revealed the presence of hepatocellular carcinoma (HCC) in six patients (5 of whom were anti-HCV positive), cholangiocarcinoma in 1 patient (anti-HCV positive) and dysplastic regenerative nodule in 1 patient (anti-HCV negative). The HCCs were surrounded by cirrhosis (3 cases), chronic active hepatitis (CAH) (n = 2) and post hepatitic fibrosis (n = 1), the cholangiocarcinoma by CAH and the regenerative nodule by cirrhotic liver. Total and replicative intermediate HCV-RNA was analyzed by reverse-transcription-nested PCR of the 5'-untranslated region. The five patients with HCC had HCV-RNA in serum, in tumorous and surrounding liver tissues. The viral nucleic acid was also detected in the cirrhotic tissue surrounding the cholangiocarcinoma but not in the tumor. Two out of 5 HCC patients had replicative intermediate RNA (negative strand) in tumorous tissue, 4 in nontumorous tissue and 3 in serum. These results demonstrate that fine needle biopsy can provide sufficient material for both histological examination and HCV-RNA determination and suggest the existence of continuous viral replication during the carcinogenic process.

Hepatitis C virus viremia following clinical resolution of acute hepatitis C

Clinical resolution of acute hepatitis C occurs in a limited proportion of cases. However, the rate of hepatitis C virus persistence remains unclear. For this purpose, we conducted a serial study of 60 patients with hepatitis C virus infection from the early stage of the disease for 24 to 80 months (average 50 months). Fourteen cases who recovered from acute hepatitis were selected from this group for prospective analysis of the behavior of liver enzymes, anti-HCV antibodies (RIBA II, Ortho Diagnostic System) and hepatitis C virus-RNA in serum and in peripheral blood lympho-mononuclear cells by nested polymerase chain reaction. Primers were derived from the 5'-untranslated region of the hepatitis C virus genome and the amplified products were detected by gel electrophoresis and a DNA enzyme immunoassay. All patients except two showed early recovery from acute hepatitis that occurred within 3 months from clinical onset. Transaminase normalization was always preceded by clearance of serum hepatitis C virus-RNA, which remained negative throughout follow-up. During the resolution phase of the disease a progressive decline in the antibody response was observed in most of the patients. At the end of the study anti-C100 was negative in half the cases, while anti-C33 and anti-C22 became negative or borderline in five cases. Hepatitis C virus-RNA was found in the peripheral blood lympho-mononuclear cells, but not in the serum, of only one of eight patients tested.(ABSTRACT TRUNCATED AT 250 WORDS)

T-cell response to structural and nonstructural hepatitis C virus antigens in persistent and self-limited hepatitis C virus infections

Twenty-nine patients with chronic hepatitis C and 15 asymptomatic hepatitis C virus antibody-positive subjects who clinically recovered from hepatitis C virus infection were studied for their peripheral blood lymphomononuclear cell proliferative response to hepatitis C virus structural and nonstructural antigens (core, envelope, nonstructural 4 and nonstructural 5) expressed in yeast as superoxide dismutase fusion proteins, in an initial attempt to define some of the features of the virus-specific immune response. Hepatitis C virus core was the most immunogenic antigen for human leukocyte antigen class II-restricted T cells in both groups of patients studied, and the proliferative response to it was the most vigorous and the most frequently expressed in comparison with the other antigens tested. The specificity of the results was supported by the lack of response to hepatitis C virus antigens by healthy uninfected controls and confirmed by recognition of recombinant core proteins of different origin (yeast and baculovirus) by polyclonal T-cell lines produced by T-cell stimulation with yeast-derived core. Each of the antigens tested was able to induce significant although variable levels of proliferative response, indicating that all can be immunogenic at the T-cell level. Significant proliferative responses to core, nonstructural 4 and nonstructural 5 antigens were more frequently detected in subjects who were able to eradicate infection than in patients with chronic hepatitis C, although the difference was statistically not significant. No difference was observed between the two groups of patients with respect to the response to the putative envelope antigens.

Simultaneous legionellosis and invasive aspergillosis in an immunocompetent patient newly treated with corticosteroids

Invasive pulmonary aspergillosis (IPA), although unusual, has been recognized in the immunocompetent host. Several cases of IPA with rapidly progressive respiratory failure have been reported in patients receiving short-term corticosteroid therapy for chronic obstructive pulmonary disease. Atypical pneumonia caused by dual infection with Legionella pneumophila and Mycoplasma pneumoniae has also been reported. We report an unusual case of simultaneous L pneumophila pneumonia and IPA in an asthma patient with suspected allergic bronchopulmonary aspergillosis newly treated with corticosteroids.

Oxidant injury alters barrier function of ferret tracheal epithelium

To understand the influence of oxidant stress on the barrier function of airway epithelium, we conducted studies to determine the effects of chemically generated reactive oxygen species on permeability, permselectivity, and active ion transport of ferret trachea. We examined the consequences of oxidant injury using ferret trachea mounted in Ussing-type chambers and bathed with a modified Krebs-Henseleit solution containing mannitol and xanthine. We added xanthine oxidase to the luminal bathing solution, which reacted with the xanthine to generate reactive oxygen species. Tissue electrical conductance and short-circuit current were significantly increased after the addition of xanthine oxidase. Simultaneous measurement of mannitol flux (as a marker of paracellular conductance) and the backflux of chloride (lumen to submucosa) demonstrated a significant oxidant-induced increase in mannitol flux and backflux of chloride. Mannitol flux and the backflux of sodium (submucosa to lumen) also increased after oxidant stress. Comparison of the diffusion of sodium relative to the diffusion of chloride in relation to predicted diffusion in free solution indicated that the paracellular pathway was cation selective after oxidant stress. Active ion transport, as reflected by the short-circuit current, was significantly increased transiently after oxidant stress. Studies with furosemide, amiloride, and diphenylamine-2-carboxylate are suggestive that oxidant stress transiently stimulates the Na-K-ATPase. These studies demonstrated that exposure to reactive oxygen species significantly altered the permeability of the tracheal epithelium as well as active ion transport.

Hepatitis C virus RNA and antibody response in the clinical course of acute hepatitis C virus infection

Hepatitis C virus RNA, anti-hepatitis C virus immune response and biochemical markers of liver injury were investigated in 17 patients with acute non-A, non-B hepatitis. At the first observation, 1 to 3 wk from the clinical onset, all patients had hepatitis C virus RNA in their serum, and most (15 of 17) were positive for second-generation anti-hepatitis C virus enzyme immunoassay. Follow-up serum samples were available for 10 patients. The rate of recombinant immunoblot assay-confirmed anti-hepatitis C virus enzyme immunoassay reactivities increased from 67% in the first 3 wk to 86% after 21 wk. Elevated ALT levels were associated with hepatitis C virus RNA positivity in most of cases, but the viral nucleic acid was also detected in sera with normal or slightly increased enzyme values. None of the single antibodies tested were related to hepatitis C virus RNA positivity or to the clinical phase of the infection. Therefore hepatitis C virus RNA determination might provide important additional information as compared with anti-hepatitis C virus markers, allowing earlier diagnosis, discrimination of active infection and, possibly, prognostic evaluation.

Cat tracheal gland cells in primary culture

Conditions for the primary culture of isolated cat tracheal gland cells were established. Cells plated onto glutaraldehyde-fixed gels of rat tail collagen grew to confluency after 8 days of culture forming a monolayer of cuboidal cells with ultrastructural characteristics of epithelial cells and immunoreactivity to antikeratins. Cultured cells synthesized and released radiolabeled high-molecular-weight glycoconjugates. Glycoconjugate secretion was increased approximately 10% in response to the cholinergic agonist, carbachol. Secretion of glycoconjugates was unrelated to regulated exocrine secretion, since these cells were devoid of secretion granules as assessed by light and electron microscopy. Confluent cultures also generated a spontaneous potential difference and short-circuit current, which were both inhibited by ouabain and increased by carbachol. This suggested gland cells contribute to fluid secretion by active ion-transport mechanisms. We also plated cells onto unfixed collagen gels that were released from the culture dish at confluency. Cells were columnar with apically oriented secretion granules that stained with alcian blue and for blood group A immunoreactivity. Secretion of radiolabeled high-molecular-weight glycoconjugates was increased 27% by carbachol. These cell culture systems may serve as models to investigate glandular secretory mechanisms and their regulation.

Arachidonic acid increases cholinergic secretory responsiveness of ferret tracheal glands

The purpose of this study was to determine if arachidonic acid could alter ferret tracheal gland secretory responsiveness to a cholinergic agonist. We prepared glandular explants and incubated the explants in medium containing [3H]glucosamine. Secretory responsiveness was expressed as the percent change in basal secretion of acid-precipitable [3H]glucosamine-labeled glycoconjugates induced by the addition of agonist with and without arachidonic acid [mean +/- SE (n)]. Addition of 10(-3) M arachidonic acid caused a significant increase in secretion [28 +/- 6% (n = 6)] compared with untreated control tissues [-10 +/- 4% (n = 7), P less than or equal to 0.05]. Carbachol (10(-7) M) increased secretion 39 +/- 9% (n = 7). The combination of 10(-3) M arachidonic acid and 10(-7) M carbachol elicited a significantly greater change in secretion compared with either agent alone [173 +/- 50% (n = 5)]. The addition of nordihydroguaiaretic acid (10(-6) M) or indomethacin (10(-6) M) partially attenuated the arachidonic acid-enhanced secretory responsiveness to carbachol. Treatment with both blockers completely inhibited the arachidonic acid-enhanced secretory responsiveness to carbachol. The effect of arachidonic acid on cholinergic stimulation was also abolished by treating the explant cultures with tetrodotoxin (10(-7) M). This hypersecretory state is most likely mediated by eicosanoid-induced release of neurotransmitters from nerve terminals.

Utility of pleural fluid analysis in predicting tube thoracostomy/decortication in parapneumonic effusions

Recommended criteria for surgical drainage of parapneumonic effusions include evidence of frank purulence, a glucose level less than 40 mg/dl, a pH of less than 7.00, or an LDH greater than 1,000 IU/L. To test the utility of these criteria, we reviewed the three-year experience of three Rochester, NY, hospitals. We identified 133 patients undergoing thoracentesis for putative parapneumonic effusions. Of 91 patients with neutrophilic exudates, 43 met one or more criteria for tube thoracostomy: 48 did not. Twenty-one of the 43, including 9 with frank empyema, underwent immediate drainage. Of the 22 who did not, 11 eventually required tube thoracostomy and/or decortication. Of the 48 not meeting any of the criteria, 7 also came to surgery. Using whether the patients eventually underwent surgery as a measure of outcome, we calculated for those patients not undergoing immediate drainage the sensitivity, specificity, positive predictive values, and negative predictive values for each of the criteria. The four criteria have relatively high specificity ranging from 82 to 96 percent, but have low sensitivity varying from only 18 percent for a positive Gram stain to 53 percent for a fluid LDH greater than 1,000 IU/L. We conclude that these criteria have limited usefulness in predicting the need for eventual chest tube drainage/decortication. Patients not meeting the criteria require close follow-up as well.

Variable effects of soman on macromolecular secretion by ferret trachea

The purpose of this study was to examine the effect of the anticholinesterase agent, soman, on macromolecular secretion by ferret trachea, in vitro. We mounted pieces of ferret trachea in Ussing-type chambers. Secreted sulfated macromolecules were radiolabeled by adding 500 microCi of 35SO4 to the submucosal medium and incubating for 17 hr. Soman added to the submucosal side produced a concentration-dependent increase in radiolabeled macromolecular release with a maximal secretory response (mean +/- SD) of 202 +/- 125% (n = 8) relative to the basal secretion rate at a concentration of 10(-7) M. The addition of either 10(-6) M pralidoxime (acetylcholinesterase reactivator) or 10(-6) M atropine blocked the response to 10(-7) M soman. At soman concentrations greater than 10(-7) M, secretion rate decreased and was not significantly different from basal secretion. Additional experiments utilizing acetylcholine and the acetylcholinesterase inhibitor, physostigmine, suggest that inhibition of secretion by high concentrations of soman may be due to a secondary antagonistic effect of soman on muscarinic receptors.

Alpha-adrenergic regulation of secretion by tracheal glands

The purpose of the present study was to begin to characterize, pharmacologically, the alpha-adrenergic regulation of glycoconjugate secretion from airway glands. Using isolated gland cells from cat trachea, we determined the binding characteristics of [3H]dihydroergocryptine ([3H]DHE), an alpha-adrenergic antagonist, with equal affinities for alpha 1- and alpha 2-adrenergic receptors. Specific binding of [3H]DHE to gland cell homogenates was saturable, of high affinity (KDapp = 4.2 nM) and inhibited with greater efficacy by epinephrine much greater than isoproterenol. Competition experiments with alpha 1- and alpha 2-adrenergic selective antagonists (prazosin and yohimbine, respectively) demonstrated high- and low-affinity sites for each antagonist, indicating the presence of both receptor subtypes. In studies of glycoconjugate secretion by cat tracheal explants, secretion was stimulated by adrenergic agonists with the rank potency: norepinephrine greater than or equal to phenylephrine greater than epinephrine much greater than clonidine. alpha-Adrenergic-stimulated secretion (epinephrine + propranolol) was inhibited by low concentrations of prazosin, but was unaffected by 100 nM yohimbine. The alpha 2-adrenergic agonists, clonidine and UK-14,304, each markedly inhibited beta-adrenergic-stimulated secretion. Collectively, these results demonstrate alpha 1-adrenergic regulation of glandular glycoconjugate secretion and suggest alpha 2-adrenergic receptors may modulate beta-adrenergic-stimulated secretion.

Efficacy of hepatic computed tomography to detect iron overload in chronic hemodialysis

The diagnostic efficacy of hepatic computed tomography density (HCTD) in comparison with serum ferritin for the detection of iron overload was investigated in uremic patients on maintenance hemodialysis (HD) and in patients with idiopathic hemochromatosis (IHC). Ten IHC patients, 38 HD patients and 40 healthy subjects underwent the CT scanning of the liver and determination of percent saturation of transferrin, serum ferritin concentration and HLA typing. Liver iron content was determined by histochemical grading and direct measurement of liver iron concentration either in IHC patients or in HD patients. Nineteen HD patients were considered to have iron overload on the basis of liver iron concentration exceeding 3.6 mumol/100 mg dry weight. The mean +/- SD values of HCTD in healthy subjects, IHC patients, HD patients with iron overload and without iron overload were 60.2 +/- 5.6, 79 +/- 5.6, 71.4 +/- 3.6, 58 +/- 3.8 Hounsfield units, respectively. HCTD showed positive correlations with liver iron concentration and serum ferritin either in IHC patients or in HD patients. The analysis of the diagnostic efficacy of HCTD in comparison with serum ferritin for the detection of excessive hepatic iron in HD patients demonstrated that HCTD had higher sensitivity, specificity, positive and negative predictive values. Cut-off points were arbitrarily fixed to 66 Hounsfield units for HCTD, 400 micrograms/liter for serum ferritin and 3.6 mumol/100 mg dry weight for liver iron concentration. Seventeen HD patients who possessed the histocompatibility antigens associated with IHC, namely HLA-A3 and/or HLA-B7 and/or HLA-B14, had liver iron concentration, serum ferritin and HCTD values higher than those of the HD patients without these "hemochromatosis alleles".(ABSTRACT TRUNCATED AT 250 WORDS)

[Results of diet treatment in 100 adult obese patients after 1-year follow-up]

One hundred overweight adult patients were subjected to a hypocaloric diet with periodic controls during a one year observation period. During the first 4 months, 98% of the patients adhered to the dietary regimen, with an initial mean percentage loss of body weight of 9.3% for the females and 8.9% for the males. The weight loss was more conspicuous during the first two months of the diet therapy and in patients with an initially higher BMI. With time, the rate of drop-out from the diet therapy increased, which resulted in a follow-up of 49% and 87% of cases at 6 and 12 months respectively, with no significant differences between the two sexes. The drop-out phenomenon resulted to be more frequent in patients with an initially lower BMI.

Effects of soman and its antidotes on tracheal mucociliary transport of ferrets

The purpose of this study was to examine the role of acetylcholinesterase on mucociliary transport by use of a potent anticholinesterase agent, soman, and potential antagonists, atropine (muscarinic antagonist) and pralidoxime (acetylcholinesterase reactivator). Initial measurements of mucociliary transport rate were obtained in anesthetized ferrets at 30-min intervals for 5.5 h. These rates remained constant at a mean of 18.2 +/- 1.0 (SE) mm/min. We studied the effects of intravenously administered soman (1-8 micrograms/kg) and observed a dose-related change in the rate of mucociliary transport [-1.1 +/- 2.7 (SE) mm/min after 1 microgram/kg, 9.8 +/- 2.9 mm/min after 5 micrograms/kg, and 14.4 +/- 4.3 mm/min after 8 micrograms/kg of soman]. Pretreatment with atropine completely prevented the response to soman, whereas pretreatment with pralidoxime did not significantly alter the response. We postulate that soman's effect on mucociliary transport relates directly to its cholinergic activity. Failure of pralidoxime to inhibit the effects of soman may relate to pralidoxime's inability to reactivate acetylcholinesterase successfully.

Influenza virus infection of tracheal gland cells in culture

Influenza virus-induced tracheobronchitis causes limited epithelial deciliation but markedly decreased mucociliary transport. This suggests that virus-induced alterations in airway mucus play a role in decreased mucociliary transport. Airway submucosal glands are a primary source of mucus. Therefore, we examined virus-gland cell interactions by exposing primary cultures of isolated feline tracheal gland cells to influenza A/Scotland/840/74 H3N2 virus for 1 h at a multiplicity of infection of 0.1. Virus production and release into the culture medium first occurred between 8 and 12 h postinfection and eventually reached a steady state that continued for at least 8 days. Virus which was produced and released by infected cells infected other monolayers, resulting in viral production similar to that after infection with stock virus. Hemadsorption assays conducted 24 h after infection demonstrated that most of the cells in a monolayer became infected. The infection was nonlytic according to cell morphology, trypan blue dye exclusion, and release of lactate dehydrogenase. Because lysis of a cell subpopulation could have been masked by subsequent cell division, we compared the uptake of [3H]thymidine by infected and control monolayers. There was no increase in uptake by infected monolayers. These results demonstrate that feline tracheal gland cells in primary culture undergo productive and nonlytic infection with influenza A virus. This model provides a unique system for the study of virus-gland interactions isolated from the influence of other tissues.

Utility of fiberoptic bronchoscopy in patients with hemoptysis and a nonlocalizing chest roentgenogram

The need for fiberoptic bronchoscopy in the patient with hemoptysis and a normal or nonlocalizing chest roentgenogram remains a subject of debate. Currently, diagnostic fiberoptic bronchoscopy is recommended as the investigative procedure of choice. To develop predictors that identify the patient in whom fiberoptic bronchoscopy is most likely to be diagnostic, we reviewed our community's experience with this population over a five-year period. We identified 196 patients with hemoptysis and a normal or nonlocalizing chest roentgenogram who underwent fiberoptic bronchoscopy. Three quarters were active or previous smokers. We examined the relationship of advancing age, sex, smoking, nonspecific roentgenographic findings and the amount, duration, and previous bouts of hemoptysis to the incidence of a diagnostic fiberoptic bronchoscopy. Twelve patients (6 percent) had bronchogenic carcinoma and 33 (17 percent) another specific cause for the hemoptysis identified by fiberoptic bronchoscopy. By univariate and discriminant analyses, we found that the three factors of age of 50 years or more, male sex, and smoking of 40 pack-years or more best predicted a diagnosis of malignancy. Bleeding in excess of 30 ml daily was associated with an increase in overall diagnostic yield. The presence of two of the three factors associated with malignancy or bleeding in excess of 30 ml daily (or both) identified 100 percent of the patients with bronchogenic carcinoma and 82 percent of all of the diagnostic fiberoptic bronchoscopic procedures. use of these criteria in selecting the patient for fiberoptic bronchoscopy could have reduced our use of the bronchoscope by 28 percent, with the remaining patients safely observed.