Genomic diversification of the specialized parasite of the fungus-growing ant symbiosis.

Fungi shape the diversity of life. Characterizing the evolution of fungi is critical to understanding symbiotic associations across kingdoms. In this study, we investigate the genomic and metabolomic diversity of the genus Escovopsis, a specialized parasite of fungus-growing ant gardens. Based on 25 high-quality draft genomes, we show that Escovopsis forms a monophyletic group arising from a mycoparasitic fungal ancestor 61.82 million years ago (Mya). Across the evolutionary history of fungus-growing ants, the dates of origin of most clades of Escovopsis correspond to the dates of origin of the fungus-growing ants whose gardens they parasitize. We reveal that genome reduction, determined by both genomic sequencing and flow cytometry, is a consistent feature across the genus Escovopsis, largely occurring in coding regions, specifically in the form of gene loss and reductions in copy numbers of genes. All functional gene categories have reduced copy numbers, but resistance and virulence genes maintain functional diversity. Biosynthetic gene clusters (BGCs) contribute to phylogenetic differences among Escovopsis spp., and sister taxa in the Hypocreaceae. The phylogenetic patterns of co-diversification among BGCs are similarly exhibited across mass spectrometry analyses of the metabolomes of Escovopsis and their sister taxa. Taken together, our results indicate that Escovopsis spp. evolved unique genomic repertoires to specialize on the fungus-growing ant-microbe symbiosis.

Burkholderia from Fungus Gardens of Fungus-Growing Ants Produces Antifungals That Inhibit the Specialized Parasite Escovopsis.

Within animal-associated microbiomes, the functional roles of specific microbial taxa are often uncharacterized. Here, we use the fungus-growing ant system, a model for microbial symbiosis, to determine the potential defensive roles of key bacterial taxa present in the ants' fungus gardens. Fungus gardens serve as an external digestive system for the ants, with mutualistic fungi in the genus Leucoagaricus converting the plant substrate into energy for the ants. The fungus garden is host to specialized parasitic fungi in the genus Escovopsis. Here, we examine the potential role of Burkholderia spp. that occur within ant fungus gardens in inhibiting Escovopsis. We isolated members of the bacterial genera Burkholderia and Paraburkholderia from 50% of the 52 colonies sampled, indicating that members of the family Burkholderiaceae are common inhabitants in the fungus gardens of a diverse range of fungus-growing ant genera. Using antimicrobial inhibition bioassays, we found that 28 out of 32 isolates inhibited at least one Escovopsis strain with a zone of inhibition greater than 1 cm. Genomic assessment of fungus garden-associated Burkholderiaceae indicated that isolates with strong inhibition all belonged to the genus Burkholderia and contained biosynthetic gene clusters that encoded the production of two antifungals: burkholdine1213 and pyrrolnitrin. Organic extracts of cultured isolates confirmed that these compounds are responsible for antifungal activities that inhibit Escovopsis but, at equivalent concentrations, not Leucoagaricus spp. Overall, these new findings, combined with previous evidence, suggest that members of the fungus garden microbiome play an important role in maintaining the health and function of fungus-growing ant colonies. IMPORTANCE Many organisms partner with microbes to defend themselves against parasites and pathogens. Fungus-growing ants must protect Leucoagaricus spp., the fungal mutualist that provides sustenance for the ants, from a specialized fungal parasite, Escovopsis. The ants take multiple approaches, including weeding their fungus gardens to remove Escovopsis spores, as well as harboring Pseudonocardia spp., bacteria that produce antifungals that inhibit Escovopsis. In addition, a genus of bacteria commonly found in fungus gardens, Burkholderia, is known to produce secondary metabolites that inhibit Escovopsis spp. In this study, we isolated Burkholderia spp. from fungus-growing ants, assessed the isolates' ability to inhibit Escovopsis spp., and identified two compounds responsible for inhibition. Our findings suggest that Burkholderia spp. are often found in fungus gardens, adding another possible mechanism within the fungus-growing ant system to suppress the growth of the specialized parasite Escovopsis.

Mapping the global prevalence, incidence, and mortality of Plasmodium falciparum, 2000-17: a spatial and temporal modelling study.

BACKGROUND: Since 2000, the scale-up of malaria control interventions has substantially reduced morbidity and mortality caused by the disease globally, fuelling bold aims for disease elimination. In tandem with increased availability of geospatially resolved data, malaria control programmes increasingly use high-resolution maps to characterise spatially heterogeneous patterns of disease risk and thus efficiently target areas of high burden. METHODS: We updated and refined the Plasmodium falciparum parasite rate and clinical incidence models for sub-Saharan Africa, which rely on cross-sectional survey data for parasite rate and intervention coverage. For malaria endemic countries outside of sub-Saharan Africa, we produced estimates of parasite rate and incidence by applying an ecological downscaling approach to malaria incidence data acquired via routine surveillance. Mortality estimates were derived by linking incidence to systematically derived vital registration and verbal autopsy data. Informed by high-resolution covariate surfaces, we estimated P falciparum parasite rate, clinical incidence, and mortality at national, subnational, and 5 × 5 km pixel scales with corresponding uncertainty metrics. FINDINGS: We present the first global, high-resolution map of P falciparum malaria mortality and the first global prevalence and incidence maps since 2010. These results are combined with those for Plasmodium vivax (published separately) to form the malaria estimates for the Global Burden of Disease 2017 study. The P falciparum estimates span the period 2000-17, and illustrate the rapid decline in burden between 2005 and 2017, with incidence declining by 27·9% and mortality declining by 42·5%. Despite a growing population in endemic regions, P falciparum cases declined between 2005 and 2017, from 232·3 million (95% uncertainty interval 198·8-277·7) to 193·9 million (156·6-240·2) and deaths declined from 925 800 (596 900-1 341 100) to 618 700 (368 600-952 200). Despite the declines in burden, 90·1% of people within sub-Saharan Africa continue to reside in endemic areas, and this region accounted for 79·4% of cases and 87·6% of deaths in 2017. INTERPRETATION: High-resolution maps of P falciparum provide a contemporary resource for informing global policy and malaria control planning, programme implementation, and monitoring initiatives. Amid progress in reducing global malaria burden, areas where incidence trends have plateaued or increased in the past 5 years underscore the fragility of hard-won gains against malaria. Efforts towards elimination should be strengthened in such areas, and those where burden remained high throughout the study period. FUNDING: Bill & Melinda Gates Foundation.

Competition among Nasal Bacteria Suggests a Role for Siderophore-Mediated Interactions in Shaping the Human Nasal Microbiota.

Resources available in the human nasal cavity are limited. Therefore, to successfully colonize the nasal cavity, bacteria must compete for scarce nutrients. Competition may occur directly through interference (e.g., antibiotics) or indirectly by nutrient sequestration. To investigate the nature of nasal bacterial competition, we performed coculture inhibition assays between nasal Actinobacteria and Staphylococcus spp. We found that isolates of coagulase-negative staphylococci (CoNS) were sensitive to growth inhibition by Actinobacteria but that Staphylococcus aureus isolates were resistant to inhibition. Among Actinobacteria, we observed that Corynebacterium spp. were variable in their ability to inhibit CoNS. We sequenced the genomes of 10 Corynebacterium species isolates, including 3 Corynebacterium propinquum isolates that strongly inhibited CoNS and 7 other Corynebacterium species isolates that only weakly inhibited CoNS. Using a comparative genomics approach, we found that the C. propinquum genomes were enriched in genes for iron acquisition and harbored a biosynthetic gene cluster (BGC) for siderophore production, absent in the noninhibitory Corynebacterium species genomes. Using a chrome azurol S assay, we confirmed that C. propinquum produced siderophores. We demonstrated that iron supplementation rescued CoNS from inhibition by C. propinquum, suggesting that inhibition was due to iron restriction through siderophore production. Through comparative metabolomics and molecular networking, we identified the siderophore produced by C. propinquum as dehydroxynocardamine. Finally, we confirmed that the dehydroxynocardamine BGC is expressed in vivo by analyzing human nasal metatranscriptomes from the NIH Human Microbiome Project. Together, our results suggest that bacteria produce siderophores to compete for limited available iron in the nasal cavity and improve their fitness.IMPORTANCE Within the nasal cavity, interference competition through antimicrobial production is prevalent. For instance, nasal Staphylococcus species strains can inhibit the growth of other bacteria through the production of nonribosomal peptides and ribosomally synthesized and posttranslationally modified peptides. In contrast, bacteria engaging in exploitation competition modify the external environment to prevent competitors from growing, usually by hindering access to or depleting essential nutrients. As the nasal cavity is a nutrient-limited environment, we hypothesized that exploitation competition occurs in this system. We determined that Corynebacterium propinquum produces an iron-chelating siderophore, and this iron-sequestering molecule correlates with the ability to inhibit the growth of coagulase-negative staphylococci. Furthermore, we found that the genes required for siderophore production are expressed in vivo Thus, although siderophore production by bacteria is often considered a virulence trait, our work indicates that bacteria may produce siderophores to compete for limited iron in the human nasal cavity.

malariaAtlas: an R interface to global malariometric data hosted by the Malaria Atlas Project.

BACKGROUND: The Malaria Atlas Project (MAP) has worked to assemble and maintain a global open-access database of spatial malariometric data for over a decade. This data spans various formats and topics, including: geo-located surveys of malaria parasite rate; global administrative boundary shapefiles; and global and regional rasters representing the distribution of malaria and associated illnesses, blood disorders, and intervention coverage. MAP has recently released malariaAtlas, an R package providing a direct interface to MAP's routinely-updated malariometric databases and research outputs. METHODS AND RESULTS: The current paper reviews the functionality available in malariaAtlas and highlights its utility for spatial epidemiological analysis of malaria. malariaAtlas enables users to freely download, visualise and analyse global malariometric data within R. Currently available data types include: malaria parasite rate and vector occurrence point data; subnational administrative boundary shapefiles; and a large suite of rasters covering a diverse range of metrics related to malaria research. malariaAtlas is here used in two mock analyses to illustrate how this data may be incorporated into a standard R workflow for spatial analysis. CONCLUSIONS: malariaAtlas is the first open-access R-interface to malariometric data, providing a new and reproducible means of accessing such data within a freely available and commonly used statistical software environment. In this way, the malariaAtlas package aims to contribute to the environment of data-sharing within the malaria research community.

Calothrixamides A and B from the Cultured Cyanobacterium Calothrix sp. UIC 10520.

Cyanobacteria are a source of chemically diverse metabolites with potential medicinal and biotechnological applications. Rapid identification of compounds is central to expedite the natural product discovery process. Mass spectrometry has been shown to be an important tool for dereplication of complex natural product samples. In addition, chromatographic separation and complementary spectroscopic analysis (e.g., UV) can enhance the confidence of the dereplication process. Here, we applied a droplet-liquid microjunction-surface sampling probe (droplet probe) coupled with UPLC-PDA-HRMS-MS/MS to identify two new natural products in situ from the freshwater strain Calothrix sp. UIC 10520. This allowed us to prioritize this strain for chemical investigation based on the presence of new metabolites very early in our discovery process, saving both time and resources. Subsequently, calothrixamides A (1) and B (2) were isolated from large-scale cultures, and the structures were elucidated by 1D and 2D NMR spectroscopy and mass spectrometry. The absolute configurations were determined by a combination of chemical degradation reactions, derivatization methods (Mosher's, Marfey's, and phenylglycine methyl ester), and J-based configurational analysis. Calothrixamides showed no cytotoxic activity against the MDA-MB-435, MDA-MB-231, and OVCAR3 cancer cell lines. They represent the first functionalized long-chain fatty acid amides reported from the Calothrix genus and from a freshwater cyanobacterium.

Ribocyclophanes A-E, Glycosylated Cyclophanes with Antiproliferative Activity from Two Cultured Terrestrial Cyanobacteria.

The cell extracts of two cultured freshwater Nostoc spp., UIC 10279 and UIC 10366, both from the suburbs of Chicago, showed antiproliferative activity against MDA-MB-231 and MDA-MB-435 cancer cell lines. Bioassay-guided fractionation led to the isolation of five glycosylated cylindrocyclophanes, named ribocyclophanes A-E (1-5) and cylindrocyclophane D (6). The structure determination was carried out by HRESIMS and 1D and 2D NMR analyses and confirmed by single-crystal X-ray crystallography. The structures of ribocyclophanes A-E (1-5) contain a ß-d-ribopyranose glycone in the rare 1 C4 conformation. Among isolated compounds, ribocyclophane D (4) showed antiproliferative activity against MDA-MB-435 and MDA-MB-231 cancer cells with an IC50 value of less than 1 µM.

Merocyclophanes C and D from the Cultured Freshwater Cyanobacterium Nostoc sp. (UIC 10110).

Merocyclophanes C and D (1 and 2) were isolated from the cell extract of the cultured cyanobacterium UIC 10110. The structures were determined by one-dimensional nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry and confirmed by 2D NMR techniques. The absolute configurations were determined using electronic circular dichroism spectroscopy. Merocyclophanes C and D represent the first known analogues of the merocyclophane core structure, a recently discovered scaffold of [7,7] paracyclophanes characterized by an α-branched methyl at C-1/C-14; 1 and 2 showed antiproliferative activity against the MDA-MB-435 cell line with IC50 values of 1.6 and 0.9 µM, respectively. Partial 16S analysis determined UIC 10110 to be a Nostoc sp., and it was found to clade with UIC 10062 Nostoc sp., the only other strain known to produce merocyclophanes. The genome of UIC 10110 was sequenced, and a biosynthetic gene cluster was identified that is proposed to encode type I and type III polyketide synthases that are potentially responsible for production of the merocyclophanes; however, further experiments will be required to verify the true function of the gene cluster. The gene cluster provides a genetic basis for the observed structural differences of the [7,7] paracyclophane core structures.

Bacillus subtilis-derived peptides disrupt quorum sensing and biofilm assembly in multidrug-resistant Staphylococcus aureus.

Multidrug-resistant Staphylococcus aureus is one of the most clinically important pathogens in the world, with infections leading to high rates of morbidity and mortality in both humans and animals. The ability of S. aureus to form biofilms protects cells from antibiotics and promotes the transfer of antibiotic resistance genes; therefore, new strategies aimed at inhibiting biofilm growth are urgently needed. Probiotic species, including Bacillus subtilis, are gaining interest as potential therapies against S. aureus for their ability to reduce S. aureus colonization and virulence. Here, we search for strains and microbially derived compounds with strong antibiofilm activity against multidrug-resistant S. aureus by isolating and screening Bacillus strains from a variety of agricultural environments. From a total of 1,123 environmental isolates, we identify a single strain B. subtilis 6D1, with a potent ability to inhibit biofilm growth, disassemble mature biofilm, and improve antibiotic sensitivity of S. aureus biofilms through an Agr quorum sensing interference mechanism. Biochemical and molecular networking analysis of an active organic fraction revealed multiple surfactin isoforms, and an uncharacterized peptide was driving this antibiofilm activity. Compared with commercial high-performance liquid chromatography grade surfactin obtained from B. subtilis, we show these B. subtilis 6D1 peptides are significantly better at inhibiting biofilm formation in all four S. aureus Agr backgrounds and preventing S. aureus-induced cytotoxicity when applied to HT29 human intestinal cells. Our study illustrates the potential of exploring microbial strain diversity to discover novel antibiofilm agents that may help combat multidrug-resistant S. aureus infections and enhance antibiotic efficacy in clinical and veterinary settings. IMPORTANCE: The formation of biofilms by multidrug-resistant bacterial pathogens, such as Staphylococcus aureus, increases these microorganisms' virulence and decreases the efficacy of common antibiotic regimens. Probiotics possess a variety of strain-specific strategies to reduce biofilm formation in competing organisms; however, the mechanisms and compounds responsible for these phenomena often go uncharacterized. In this study, we identified a mixture of small probiotic-derived peptides capable of Agr quorum sensing interference as one of the mechanisms driving antibiofilm activity against S. aureus. This collection of peptides also improved antibiotic killing and protected human gut epithelial cells from S. aureus-induced toxicity by stimulating an adaptive cytokine response. We conclude that purposeful strain screening and selection efforts can be used to identify unique probiotic strains that possess specially desired mechanisms of action. This information can be used to further improve our understanding of the ways in which probiotic and probiotic-derived compounds can be applied to prevent bacterial infections or improve bacterial sensitivity to antibiotics in clinical and agricultural settings.

Uses of Fecal Microbiota Transplantation in Neurodegenerative Disease: A Scoping Review.

Fecal microbiota transplantation (FMT) is the administration of fecal bacteria from a healthy donor into the intestinal tract of a recipient in order to directly change the recipient's gut microbial composition and confer a health benefit. The relationship between the gut microbiome and the central nervous system, termed the gut-brain axis, has been a frequent topic of gut microbiome studies. Commensal gut bacteria communicate with the central nervous system through various hormones, cytokines, and neural pathways. Therefore, influencing the gut microbiome via FMT may have the potential in treating symptoms of neurodegenerative conditions. This study aims to identify current uses of FMT in treating neurodegenerative diseases and highlight areas of future investigation. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework, a literature search was conducted of peer-reviewed sources on September 27, 2022, from Embase, MEDLINE, Web of Science, and Cochrane Central. Search terms were utilized that were related to the application of FMT and neurodegenerative disorders and limited those human studies, those that were published in English, and those that were published between 2017 and 2022. The initial search yielded 450 unique articles, and after the assessment of the title and abstract for inclusion and exclusion criteria, six articles were identified for full-text review. Studies that focused on either Parkinson's disease (PD) or multiple sclerosis (MS) demonstrated improvements in both motor symptoms and non-motor symptoms. FMT was also shown to provide significant relief of constipation and general gastrointestinal (GI) symptoms in all conditions studied. The studies related to MS showed the most mixed results with regard to symptomatic improvement. The data on the use of FMT as a treatment for neurodegenerative disorders is limited; however, studies have shown not only improvement in GI symptoms but also improvement in the cognitive symptoms of PD and dementia. The data on FMT as a treatment to improve the motor symptoms of PD is both more complete and more compelling than the data on the motor symptoms of MS. The studies that were reviewed showed no major adverse effects of FMT and generally promising results. There is a strong case to be made for larger, more well-controlled studies to be done on FMT and its potential use as a treatment not only for GI symptoms but for the motor and cognitive symptoms of neurodegenerative diseases.

Pollen Streptomyces Produce Antibiotic That Inhibits the Honey Bee Pathogen Paenibacillus larvae.

Humans use natural products to treat disease; similarly, some insects use natural products produced by Actinobacteria to combat infectious pathogens. Honey bees, Apis mellifera, are ecologically and economically important for their critical role as plant pollinators and are host to diverse and potentially virulent pathogens that threaten hive health. Here, we provide evidence that Actinobacteria that can suppress pathogenic microbes are associated with A. mellifera. We show through culture-dependent approaches that Actinobacteria in the genus Streptomyces are commonly isolated from foraging bees, and especially common in pollen stores. One strain, isolated from pollen stores, exhibited pronounced inhibitory activity against Paenibacillus larvae, the causative agent of American foulbrood. Bioassay-guided HPLC fractionation, followed by NMR and mass spectrometry, identified the known macrocyclic polyene lactam, piceamycin that was responsible for this activity. Further, we show that in its purified form, piceamycin has potent inhibitory activity toward P. larvae. Our results suggest that honey bees may use pollen-derived Actinobacteria and their associated small molecules to mediate colony health. Given the importance of honey bees to modern agriculture and their heightened susceptibility to disease, the discovery and development of antibiotic compounds from hives could serve as an important strategy in supporting disease management within apiaries.

Fuzzy boundaries: Simulation and expertise in bushfire prediction.

It is becoming apparent that changes in climatic and demographic distributions are increasing the frequency and social impact of many 'natural hazards', including wildfires (or 'bushfires' in Australia). Across many national contexts, the governmental agencies legally responsible for 'managing' such hazards been called upon to provide greater foresight into the potential consequences, occurrence and behaviour of these dynamic phenomena. These conditions, of growing occurrence and expectation, have given rise to new anticipatory regimes, tools, practitioners and expertise tasked with revealing near and distant fiery futures. Drawing on interviews with Fire Behaviour Analysts from across the fire-prone continent of Australia, this article examines how their expertise has emerged and become institutionalized, exploring how its embedding in bushfire management agencies reveals cultural boundaries and tensions. This article provides important insight into the human and nonhuman infrastructures enrolled in predicting and managing landscape fires, foregrounding the wider social and political implications of these infrastructures and how their 'fuzzy boundaries' are negotiated by practitioners. Such empirical studies of expertise in practice are also, we suggest, necessary to the continued refinement of existing critiques of expertise as an individual capacity, derived from science and serving established social orders.

15N Stable Isotope Labeling and Comparative Metabolomics Facilitates Genome Mining in Cultured Cyanobacteria.

As genome mining becomes a more widely used approach to identify bacterial natural products, the challenge of matching biosynthetic gene clusters to their cognate secondary metabolites has become more apparent. Bioinformatic platforms such as AntiSMASH have made great progress in predicting chemical structures from genetic information, however the predicted structures are often incomplete. This complicates identifying the predicted compounds by mass spectrometry. Secondary metabolites produced by cyanobacteria represent a unique opportunity for bridging this gap. Cultured cyanobacteria incorporate inorganic nitrogen provided in chemically defined media into all nitrogen-containing secondary metabolites. Thus, stable isotope labeling with 15N labeled nitrate and subsequent comparative metabolomics can be used to match biosynthetic gene clusters to their cognate compounds in cell extracts. Analysis of the sequenced genome of Nostoc sp. UIC 10630 identified six biosynthetic gene clusters predicted to encode the production of a secondary metabolite with at least one nitrogen atom. Comparative metabolomic analysis of the 15N labeled and unlabeled cell extracts revealed four nitrogen containing compounds that contained the same number of nitrogen atoms as were predicted in the biosynthetic gene clusters. Two of the four compounds were new secondary metabolites, and their structures were elucidated by NMR, HRESIMS, and MS/MS.

The impact of culture conditions on growth and metabolomic profiles of freshwater cyanobacteria.

Cultured cyanobacteria produce secondary metabolites with a wide range of biological activities and are an important source of natural products. In the context of secondary metabolite discovery, microbial culture conditions are expected to support optimum growth, induce maximum chemical diversity, and be suitable for the majority of cyanobacterial strains. We investigated the effect of nitrate and phosphate on biomass production and metabolomic profiles of three filamentous freshwater cyanobacterial strains: cf. Oscillatoria sp. UIC 10045, Scytonema sp. UIC 10036, and Nostoc sp. UIC 10110. A standardized inoculation procedure allowed for the assessment of cell mass production. Dried cyanobacterial cell mass was extracted and analyzed by liquid chromatography coupled with high resolution mass spectrometry (UPLC-HRMS), followed by comparative metabolomics analysis using XCMS Online. Results showed that low nitrate media significantly reduced cell mass production for all three strains. Low nitrate also induced production of primary metabolites (heterocyst glycolipids) in strains UIC 10036 and UIC 10110. Changes in phosphate levels affected each strain differently. Strain UIC 10110 showed a significant increase in production of merocyclophane C when cultivated in low phosphate, while strain UIC 10036 displayed higher production of tolytoxin under high phosphate. Additionally, these experiments led to the identification of a potentially new peptide produced by strain UIC 10036.

Inducing Kondo screening of vacancy magnetic moments in graphene with gating and local curvature.

In normal metals the magnetic moment of impurity-spins disappears below a characteristic Kondo temperature which marks the formation of a cloud of conduction-band electrons that screen the local-moment. In contrast, moments embedded in insulators remain unscreened at all temperatures. What then is the fate of magnetic-moments in intermediate, pseudogap systems, such as graphene? Theory predicts that coupling to the conduction-band electrons will drive a quantum phase transition between a local-moment phase and a Kondo-screened phase. However, attempts to experimentally confirm this prediction and its intriguing consequences, such as electrostatically tunable magnetic-moments, have been elusive. Here we report the observation of Kondo-screening and the quantum phase-transition between screened and unscreened phases of vacancy magnetic moments in graphene. Using scanning tunneling spectroscopy and numerical renormalization-group calculations we show that this transition enables to control the screening of local moments by tuning the gate voltage and the local curvature of the graphene membrane.

Incidence of diarrhea: poor parental recall ability.

Several methodological issues may have an impact on the incidence rates of childhood acute diarrhea reported by community-based studies. This study was performed to assess the impact of parental recall ability and definition of diarrhea on the estimate of incidence of acute diarrhea. Eighty-four children younger than 40 months were randomly selected and visited every other day for four weeks and the occurrence of diarrhea was registered. On the last day of the study, another visit was performed and the informants were inquired about the occurrence of diarrhea during the previous four weeks. Data gathered during the four weeks were compared to those obtained on the last visit. Additionally, the informants' definition of diarrhea was investigated and compared to the one adopted by this study. During the observation period, 33 children suffered diarrhea, but only 10 (30.3%) informants reported the occurrence of diarrhea. Although 42.4% of those informants reported that their children had been ill over that period, they did not report diarrhea. Further, 60.6% children who had diarrhea suffered at least one episode in the two weeks prior to the visitation. The same definition of diarrhea used in this study was adopted by 52.1% of the informants inquired. Parental recall is an unreliable method to estimate the incidence of diarrhea and studies with a short interval between the visits should be necessary to correctly evaluate this important health problem. Moreover, assessing the informants' own definition of diarrhea is a significant contribution to the interpretation of the results.

Implantation of an empty carbon fiber composite frame cage after single-level anterior cervical discectomy in the treatment of cervical disc herniation: preliminary results.

OBJECT: The authors sought to evaluate retrospectively the radiological and clinical outcome of anterior cervical discectomy followed by implantation of an empty carbon fiber composite frame cage (CFCF) in the treatment of patients with cervical disc herniation and monoradiculopathy. METHODS: Twenty-five consecutive patients (12 men, 13 women, mean age 45 years) with monoradiculopathy due to cervical disc herniation were treated by anterior cervical discectomy followed by implantation of an empty CFCF cage. On lateral flexion-extension radiographs segmental stability at a mean follow up of 14 months (range 5-31 months) was demonstrated in all 25 patients, and bone fusion was documented in 24 of 25 patients. The mean anterior intervertebral body height was 3.4 mm preoperatively and 3.8 mm at follow up in 20 patients. In these patients the mean segmental angle (angle between lower endplate of lower and upper vertebra) was 0.9 degrees preoperatively and 3.1 degrees at follow up. In the remaining five patients preoperative images were not retrievable. Self-scored neck pain based on a visual analog scale (1, minimum; 10, maximum) changed from a preoperative average of 5.6 to an average of 2 at follow up; radicular pain was reduced from 7.7 to 2.1 postoperatively. Analysis of the SF12 questionnaires showed a significant improvement in both the physical capacity score (preoperative mean 32.4 points; follow up 46 points) and the mental capacity score (preoperative mean 45.8 points; follow up 57.5 points). CONCLUSIONS: Implantation of an empty CFCF cage in the treatment of cervical disc herniation and monoradiculopathy avoids donor site morbidity associated with autologous bone grafting as well as the use of any supplementary material inside the cage. Restoration or maintenance of intervertebral height and thus segmental lordosis and a very high rate of segmental stability and fusion are achieved using this technique.

Variation in average costs among federally sponsored state-organized cancer detection programs: economies of scale?

BACKGROUND: Societal cost-effectiveness analysis and its variants help decision makers achieve an efficient allocation of resources across the set of all possible health interventions. Sometimes, however, decision makers are focused instead on the efficient allocation of resources within a particular intervention program that has already been implemented. This is especially true when the intervention is being delivered at several different sites. An analysis of average cost across program sites may help program officials to maximize the health benefits that can be achieved with limited resources. In this article, the authors present such an analysis, with special attention paid to the possible existence and implications of economies of scale. METHODS: Focusing on federally sponsored, state-organized cancer detection programs, the authors modeled 19 state programs as productive processes and examined their average costs over a 2- to 5-year period of operation. They considered 3 alternative definitions of output: women served, screens performed, and conditions detected. Average federal costs and average total costs were estimated for each grant period. Multivariate regression analysis was used to help explain the variation in average costs. RESULTS: The average cost estimates were distributed in a skewed pattern with the majority of observations falling close to the median and substantially below the mean. For all measures considered, average cost decreased as output expanded. This inverse relationship between average cost and output level persisted even after controlling for the effects of other predictors, suggesting the possible existence of economies of scale. DISCUSSION: The potential existence of economies of scale calls into question the assumption of a constant average cost frequently made in economic analyses of proposed public health programs. It also implies that a) differences in output level should be taken into account when comparing operating efficiency across program sites; b) conclusions from societal cost-effectiveness analyses may depend on the level of output at which the programs are evaluated; c) cost projections could be inaccurate if they do not take into account the decrease in average cost that occurs as output expands; and d) gains might be possible if similar programs with limited output potential are integrated, perhaps through cost sharing.