The nose is the best niche for detection of experimental pneumococcal colonisation in adults of all ages, using nasal wash

Previous studies have suggested that the pneumococcal niche changes from the nasopharynx to the oral cavity with age. We use an Experimental Human Pneumococcal Challenge model to investigate pneumococcal colonisation in different anatomical niches with age. Healthy adults (n = 112) were intranasally inoculated with Streptococcus pneumoniae serotype 6B (Spn6B) and were categorised as young 18-55 years (n = 57) or older > 55 years (n = 55). Colonisation status (frequency and density) was determined by multiplex qPCR targeting the lytA and cpsA-6A/B genes in both raw and culture-enriched nasal wash and oropharyngeal swab samples collected at 2-, 7- and 14-days post-exposure. For older adults, raw and culture-enriched saliva samples were also assessed. 64% of NW samples and 54% of OPS samples were positive for Spn6B in young adults, compared to 35% of NW samples, 24% of OPS samples and 6% of saliva samples in older adults. Many colonisation events were only detected in culture-enriched samples. Experimental colonisation was detected in 72% of young adults by NW and 63% by OPS. In older adults, this was 51% by NW, 36% by OPS and 9% by saliva. The nose, as assessed by nasal wash, is the best niche for detection of experimental pneumococcal colonisation in both young and older adults.

Impact of 13-Valent Pneumococcal Conjugate Vaccine on Colonization and Invasive Disease in Cambodian Children

BACKGROUND

Cambodia introduced the 13-valent pneumococcal conjugate vaccine (PCV13) in January 2015 using a 3 + 0 dosing schedule and no catch-up campaign. We investigated the effects of this introduction on pneumococcal colonization and invasive disease in children aged <5 years.

METHODS

There were 6 colonization surveys done between January 2014 and January 2018 in children attending the outpatient department of a nongovernmental pediatric hospital in Siem Reap. Nasopharyngeal swabs were analyzed by phenotypic and genotypic methods to detect pneumococcal serotypes and antimicrobial resistance. Invasive pneumococcal disease (IPD) data for January 2012-December 2018 were retrieved from hospital databases. Pre-PCV IPD data and pre-/post-PCV colonization data were modelled to estimate vaccine effectiveness (VE).

RESULTS

Comparing 2014 with 2016-2018, and using adjusted prevalence ratios, VE estimates for colonization were 16.6% (95% confidence interval [CI] 10.6-21.8) for all pneumococci and 39.2% (95% CI 26.7-46.1) for vaccine serotype (VT) pneumococci. There was a 26.0% (95% CI 17.7-33.0) decrease in multidrug-resistant pneumococcal colonization. The IPD incidence was estimated to have declined by 26.4% (95% CI 14.4-35.8) by 2018, with a decrease of 36.3% (95% CI 23.8-46.9) for VT IPD and an increase of 101.4% (95% CI 62.0-145.4) for non-VT IPD.

CONCLUSIONS

Following PCV13 introduction into the Cambodian immunization schedule, there have been declines in VT pneumococcal colonization and disease in children aged <5 years. Modelling of dominant serotype colonization data produced plausible VE estimates.

Pneumococcal carriage in vaccine-eligible children and unvaccinated infants in Lao PDR two years following the introduction of the 13-valent pneumococcal conjugate vaccine

Pneumococcal carriage is a prerequisite for disease, and underpins herd protection provided by pneumococcal conjugate vaccines (PCVs). There are few data on the impact of PCVs in lower income settings, particularly in Asia. In 2013, the Lao People's Democratic Republic (Lao PDR) introduced 13-valent PCV (PCV13) as a 3 + 0 schedule (doses at 6, 10 and 14 weeks of age) with limited catch-up vaccination. We conducted two cross-sectional carriage surveys (pre- and two years post-PCV) to assess the impact of PCV13 on nasopharyngeal pneumococcal carriage in 5-8 week old infants (n = 1000) and 12-23 month old children (n = 1010). Pneumococci were detected by quantitative real-time PCR, and molecular serotyping was performed using DNA microarray. Post PCV13, there was a 23% relative reduction in PCV13-type carriage in children aged 12-23 months (adjusted prevalence ratio [aPR] 0.77 [0.61-0.96]), and no significant change in non-PCV13 serotype carriage (aPR 1.11 [0.89-1.38]). In infants too young to be vaccinated, there was no significant change in carriage of PCV13 serotypes (aPR 0.74 [0.43-1.27]) or non-PCV13 serotypes (aPR 1.29 [0.85-1.96]), although trends were suggestive of indirect effects. Over 70% of pneumococcal-positive samples contained at least one antimicrobial resistance gene, which were more common in PCV13 serotypes (p < 0.001). In 12-23 month old children, pneumococcal density of both PCV13 serotypes and non-PCV13 serotypes was higher in PCV13-vaccinated compared with undervaccinated children (p = 0.004 and p < 0.001, respectively). This study provides evidence of PCV13 impact on carriage in a population without prior PCV7 utilisation, and provides important data from a lower-middle income setting in Asia. The reductions in PCV13 serotype carriage in vaccine-eligible children are likely to result in reductions in pneumococcal transmission and disease in Lao PDR.

Transcriptional Profiling Mycobacterium tuberculosis from Patient Sputa

The emergence of drug resistance threatens to destroy tuberculosis control programs worldwide, with resistance to all first-line drugs and most second-line drugs detected. Drug tolerance (or phenotypic drug resistance) is also likely to be clinically relevant over the 6-month long standard treatment for drug-sensitive tuberculosis. Transcriptional profiling the response of Mycobacterium tuberculosis to antimicrobial drugs offers a novel interpretation of drug efficacy and mycobacterial drug-susceptibility that likely varies in dynamic microenvironments, such as the lung. This chapter describes the noninvasive sampling of tuberculous sputa and techniques for mRNA profiling M. tb bacilli during patient therapy to characterize real-world drug actions.

Impact of the 13-valent pneumococcal conjugate vaccine on Streptococcus pneumoniae multiple serotype carriage

INTRODUCTION

Pneumococcal multiple serotype carriage is important for evolution of the species and to understand how the pneumococcal population is changing with vaccination. We aimed to determine the impact of the 13-valent pneumococcal conjugate vaccine (PCV13) on multiple serotype carriage.

METHODS AND MATERIALS

Nasopharyngeal samples from fully vaccinated pneumococcal carriers (4 doses of PCV13, n=141, aged 18-72months) or from non-vaccinated pneumococcal carriers (0 doses of any PCV, n=140, same age group) were analyzed. Multiple serotype carriage was evaluated by DNA hybridization with a molecular serotyping microarray that detects all known serotypes.

RESULTS

Vaccinated children had a lower prevalence of multiple serotype carriage than the non-vaccinated group (20.6% vs 29.3%, p=0.097), and a significantly lower proportion of PCV13 serotypes (6.4% vs 38.5%, p=0.0001). PCV13 serotypes found among vaccinated children were mostly detected as a minor serotype in co-colonization with a more abundant non-vaccine serotype. Vaccinated children were colonized by a significantly higher proportion of commensal non-pneumococcal Streptococcus spp. (58.2% vs 42.8%, p=0.012). In vaccinated children there were significantly less non-vaccine type (NVT) co-colonization events than expected based on the distribution of these serotypes in non-vaccinated children.

CONCLUSIONS

The results suggest that vaccinated children have lower pneumococcal multiple serotype carriage prevalence due to higher competitive abilities of non-vaccine serotypes expanding after PCV13 use. This might represent an additional benefit of PCV13, as decreased co-colonization rates translate into decreased opportunities for horizontal gene transfer and might have implications for the evolution and virulence of pneumococci.

An Lck-cre transgene accelerates autoantibody production and lupus development in (NZB × NZW)F1 mice

Lupus is an autoimmune disease characterized by the development of antinuclear autoantibodies and immune complex-mediated tissue damage. T cells in lupus patients appear to undergo apoptosis at an increased rate, and this enhanced T cell apoptosis has been postulated to contribute to lupus pathogenesis by increasing autoantigen load. However, there is no direct evidence to support this hypothesis. In this study, we show that an Lck-cre transgene, which increases T cell apoptosis as a result of T cell-specific expression of cre recombinase, accelerates the development of autoantibodies and nephritis in lupus-prone (NZB × NZW)F1 mice. Although the enhanced T cell apoptosis in Lck-cre transgenic mice resulted in an overall decrease in the relative abundance of splenic CD4(+) and CD8(+) T cells, the proportion of activated CD4(+) T cells was increased and no significant change was observed in the relative abundance of suppressive T cells. We postulate that the Lck-cre transgene promoted lupus by enhancing T cell apoptosis, which, in conjunction with the impaired clearance of apoptotic cells in lupus-prone mice, increased the nuclear antigen load and accelerated the development of anti-nuclear autoantibodies. Furthermore, our results also underscore the importance of including cre-only controls in studies using the cre-lox system.

High multiple carriage and emergence of Streptococcus pneumoniae vaccine serotype variants in Malawian children

BACKGROUND

Carriage of either single or multiple pneumococcal serotypes (multiple carriage) is a prerequisite for developing invasive pneumococcal disease. However, despite the reported high rates of pneumococcal carriage in Malawi, no data on carriage of multiple serotypes has been reported previously. Our study provides the first description of the prevalence of multiple pneumococcal carriage in Malawi.

METHODS

The study was conducted in Blantyre and Karonga districts in Malawi, from 2008 to 2012. We recruited 116 children aged 0-13 years. These children were either HIV-infected (N = 44) or uninfected (N = 72). Nasopharyngeal samples were collected using sterile swabs. Pneumococcal serotypes in the samples were identified by microarray. Strains that could not be typed by microarray were sequenced to characterise possible genetic alterations within the capsular polysaccharide (CPS) locus.

RESULTS

The microarray identified 179 pneumococcal strains (from 116 subjects), encompassing 43 distinct serotypes and non-typeable (NT) strains. Forty per cent (46/116) of children carried multiple serotypes. Carriage of vaccine type (VT) strains was higher (p = 0.028) in younger (0-2 years) children (71 %, 40/56) compared to older (3-13 years) children (50 %, 30/60). Genetic variations within the CPS locus of known serotypes were observed in 19 % (34/179) of the strains identified. The variants included 13-valent pneumococcal conjugate vaccine (PCV13) serotypes 6B and 19A, and the polysaccharide vaccine serotype 20. Serotype 6B variants were the most frequently isolated (47 %, 16/34). Unlike the wild type, the CPS locus of the 6B variants contained an insertion of the licD-family phosphotransferase gene. The CPS locus of 19A- and 20-variants contained an inversion in the sugar-biosynthesis (rmlD) gene and a 717 bp deletion within the transferase (whaF) gene, respectively.

CONCLUSIONS

The high multiple carriage in Malawian children provides opportunities for genetic exchange through horizontal gene transfer. This may potentially lead to CPS locus variants and vaccine escape. Variants reported here occurred naturally, however, PCV13 introduction could exacerbate the CPS genetic variations. Further studies are therefore recommended to assess the invasive potential of these variants and establish whether PCV13 would offer cross-protection. We have shown that younger children (0-2 years) are a reservoir of VT serotypes, which makes them an ideal target for vaccination.

Clinical application of whole-genome sequencing to inform treatment for multidrug-resistant tuberculosis cases

The treatment of drug-resistant tuberculosis cases is challenging, as drug options are limited, and the existing diagnostics are inadequate. Whole-genome sequencing (WGS) has been used in a clinical setting to investigate six cases of suspected extensively drug-resistant Mycobacterium tuberculosis (XDR-TB) encountered at a London teaching hospital between 2008 and 2014. Sixteen isolates from six suspected XDR-TB cases were sequenced; five cases were analyzed in a clinically relevant time frame, with one case sequenced retrospectively. WGS identified mutations in the M. tuberculosis genes associated with antibiotic resistance that are likely to be responsible for the phenotypic resistance. Thus, an evidence base was developed to inform the clinical decisions made around antibiotic treatment over prolonged periods. All strains in this study belonged to the East Asian (Beijing) lineage, and the strain relatedness was consistent with the expectations from the case histories, confirming one contact transmission event. We demonstrate that WGS data can be produced in a clinically relevant time scale some weeks before drug sensitivity testing (DST) data are available, and they actively help clinical decision-making through the assessment of whether an isolate (i) has a particular resistance mutation where there are absent or contradictory DST results, (ii) has no further resistance markers and therefore is unlikely to be XDR, or (iii) is identical to an isolate of known resistance (i.e., a likely transmission event). A small number of discrepancies between the genotypic predictions and phenotypic DST results are discussed in the wider context of the interpretation and reporting of WGS results.

A cross-sectional observational study of pneumococcal carriage in children, their parents, and older adults following the introduction of the 7-valent pneumococcal conjugate vaccine

Using nasopharyngeal carriage as a marker of vaccine impact, pneumococcal colonization and its relation to invasive disease were examined in children, their parents, and older adults in the United Kingdom following introduction of 7-valent pneumococcal conjugate vaccine (PCV7) and prior to 13-valent pneumococcal conjugate vaccine (PCV13).A cross-sectional observational study was conducted, collecting nasopharyngeal swabs from children aged 25 to 55 months who had previously received 3 doses of PCV7, their parents, and adults aged ≥65 years. Pneumococcal serotyping was conducted according to World Health Organization guidelines with nontypeable isolates further analyzed by molecular serotyping. A national invasive disease surveillance program was conducted throughout the corresponding period.Pneumococcus was isolated from 47% of children, 9% of parents, and 2.2% of older adults. For these groups, the percentage of serotypes covered by PCV7 were 1.5%, 0.0%, and 15.4%, with a further 20.1%, 44.4%, and 7.7% coverage added by those in PCV13. In each group, the percentage of disease due to serotypes covered by PCV7 were 1.0%, 7.4% and 5.1% with a further 65.3%, 42.1%, and 61.4% attributed to those in PCV13.The prevalence of carriage is the highest in children, with direct vaccine impact exemplified by low carriage and disease prevalence of PCV7 serotypes in vaccinated children, whereas the indirect effects of herd protection are implied by similar observations in unvaccinated parents and older adults.

Extensive horizontal gene transfer during Staphylococcus aureus co-colonization in vivo

Staphylococcus aureus is a commensal and major pathogen of humans and animals. Comparative genomics of S. aureus populations suggests that colonization of different host species is associated with carriage of mobile genetic elements (MGE), particularly bacteriophages and plasmids capable of encoding virulence, resistance, and immune evasion pathways. Antimicrobial-resistant S. aureus of livestock are a potential zoonotic threat to human health if they adapt to colonize humans efficiently. We utilized the technique of experimental evolution and co-colonized gnotobiotic piglets with both human- and pig-associated variants of the lineage clonal complex 398, and investigated growth and genetic changes over 16 days using whole genome sequencing. The human isolate survived co-colonization on piglets more efficiently than in vitro. During co-colonization, transfer of MGE from the pig to the human isolate was detected within 4 h. Extensive and repeated transfer of two bacteriophages and three plasmids resulted in colonization with isolates carrying a wide variety of mobilomes. Whole genome sequencing of progeny bacteria revealed no acquisition of core genome polymorphisms, highlighting the importance of MGE. Staphylococcus aureus bacteriophage recombination and integration into novel sites was detected experimentally for the first time. During colonization, clones coexisted and diversified rather than a single variant dominating. Unexpectedly, each piglet carried unique populations of bacterial variants, suggesting limited transmission of bacteria between piglets once colonized. Our data show that horizontal gene transfer occurs at very high frequency in vivo and significantly higher than that detectable in vitro.

A point mutation in cpsE renders Streptococcus pneumoniae nonencapsulated and enhances its growth, adherence and competence

BACKGROUND

The polysaccharide capsule is a major virulence factor of the important human pathogen Streptococcus pneumoniae. However, S. pneumoniae strains lacking capsule do occur.

RESULTS

Here, we report a nasopharyngeal isolate of Streptococcus pneumoniae composed of a mixture of two phenotypes; one encapsulated (serotype 18C) and the other nonencapsulated, determined by serotyping, electron microscopy and fluorescence isothiocyanate dextran exclusion assay.By whole genome sequencing, we demonstrated that the phenotypes differ by a single nucleotide base pair in capsular gene cpsE (C to G change at gene position 1135) predicted to result in amino acid change from arginine to glycine at position 379, located in the cytoplasmic, enzymatically active, region of this transmembrane protein. This SNP is responsible for loss of capsule production as the phenotype is transferred with the capsule operon. The nonencapsulated variant is superior in growth in vitro and is also 117-fold more adherent to and more invasive into Detroit 562 human epithelial cells than the encapsulated variant.Expression of six competence pathway genes and one competence-associated gene was 11 to 34-fold higher in the nonencapsulated variant than the encapsulated and transformation frequency was 3.7-fold greater.

CONCLUSIONS

We identified a new single point mutation in capsule gene cpsE of a clinical S. pneumoniae serotype 18C isolate sufficient to cause loss of capsule expression resulting in the co-existence of the encapsulated and nonencapsulated phenotype. The mutation caused phenotypic changes in growth, adherence to epithelial cells and transformability. Mutation in capsule gene cpsE may be a way for S. pneumoniae to lose its capsule and increase its colonization potential.

Genome sequencing and characterization of an extensively drug-resistant sequence type 111 serotype O12 hospital outbreak strain of Pseudomonas aeruginosa

A series of extensively drug-resistant isolates of Pseudomonas aeruginosa from two outbreaks in UK hospitals were characterized by whole genome sequencing (WGS). Although these isolates were resistant to antibiotics other than colistin, we confirmed that they are still sensitive to disinfectants. The sequencing confirmed that isolates in the larger outbreak were serotype O12, and also revealed that they belonged to sequence type ST111, which is a major epidemic strain of P. aeruginosa throughout Europe. As this is the first reported sequence of an ST111 strain, the genome was examined in depth, focusing particularly on antibiotic resistance and potential virulence genes, and on the reported regions of genome plasticity. High degrees of sequence similarity were discovered between outbreak isolates collected from recently infected patients, isolates from sinks, an isolate from the sewer, and a historical isolate, suggesting that the ST111 strain has been endemic in the hospital for many years. The ability to translate easily from outbreak investigation to detailed genome biology by use of the same data demonstrates the flexibility of WGS application in a clinical setting.

Dominant role of nucleotide substitution in the diversification of serotype 3 pneumococci over decades and during a single infection

Streptococcus pneumoniae of serotype 3 possess a mucoid capsule and cause disease associated with high mortality rates relative to other pneumococci. Phylogenetic analysis of a complete reference genome and 81 draft sequences from clonal complex 180, the predominant serotype 3 clone in much of the world, found most sampled isolates belonged to a clade affected by few diversifying recombinations. However, other isolates indicate significant genetic variation has accumulated over the clonal complex's entire history. Two closely related genomes, one from the blood and another from the cerebrospinal fluid, were obtained from a patient with meningitis. The pair differed in their behaviour in a mouse model of disease and in their susceptibility to antimicrobials, with at least some of these changes attributable to a mutation that up-regulated the patAB efflux pump. This indicates clinically important phenotypic variation can accumulate rapidly through small alterations to the genotype.

Nontypeable pneumococcal isolates among navajo and white mountain apache communities: are these really a cause of invasive disease?

BACKGROUND

Pneumococci could evade pneumococcal conjugate vaccines (PCV) by modifying, mutating, or deleting vaccine-serotype capsule genes or by downregulating capsule production. We sought to assess whether pneumococci that are nontypeable (NT) by the Quellung reaction truly lack capsule genes or are failing to produce capsule in vitro.

METHODS

We applied multilocus sequence typing and a microarray for detection of pneumococcal polysaccharide capsule biosynthesis genes to NT carriage (children aged <5 years; years 1997-2000, 2006-2008) and NT invasive disease (IPD) (all ages; years 1994-2007) isolates from Native American communities.

RESULTS

Twenty-seven of 28 (96.4%) NT IPD isolates had sequence types (STs) typically found among typeable IPD isolates and contained whole or fragments of capsule genes that matched known serotypes; 1 NT-IPD isolate had a profile resembling NT carriage isolates. Forty-nine of 76 (64.5%) NT carriage isolates had STs that typically lack capsule genes and were similar to NT carriage isolates found globally.

CONCLUSIONS

This is the first documentation of IPD from an NT strain confirmed to lack all known capsule genes. Most NT IPD isolates have or had the capacity to produce capsule, whereas a majority of NT carriage isolates lack this capacity. We found no evidence of pneumococcal adaptation to PCV7 via downregulation or deletion of vaccine-serotype capsule genes.

Variation at the capsule locus, cps, of mistyped and non-typable Streptococcus pneumoniae isolates

The capsule polysaccharide locus (cps) is the site of the capsule biosynthesis gene cluster in encapsulated Streptococcus pneumoniae. A set of pneumococcal samples and non-pneumococcal streptococci from Denmark, the Gambia, the Netherlands, Thailand, the UK and the USA were sequenced at the cps locus to elucidate serologically mistyped or non-typable isolates. We identified a novel serotype 33B/33C mosaic capsule cluster and previously unseen serotype 22F capsule genes, disrupted and deleted cps clusters, the presence of aliB and nspA genes that are unrelated to capsule production, and similar genes in the non-pneumococcal samples. These data provide greater understanding of diversity at a locus which is crucial to the antigenic diversity of the pathogen and current vaccine strategies.

The distribution of mobile genetic elements (MGEs) in MRSA CC398 is associated with both host and country

Methicillin-resistant Staphylococcus aureus clonal complex (CC) 398 has emerged from pigs to cause human infections in Europe and North America. We used a new 62-strain S. aureus microarray (SAM-62) to compare genomes of isolates from three geographical areas (Belgium, Denmark, and Netherlands) to understand how CC398 colonizes different mammalian hosts. The core genomes of 44 pig isolates and 32 isolates from humans did not vary. However, mobile genetic element (MGE) distribution was variable including SCCmec. φ3 bacteriophage and human specificity genes (chp, sak, scn) were found in invasive human but not pig isolates. SaPI5 and putative ruminant specificity gene variants (vwb and scn) were common but not pig specific. Virulence and resistance gene carriage was host associated but country specific. We conclude MGE exchange is frequent in CC398 and greatest among populations in close contact. This feature may help determine epidemiological associations among isolates of the same lineage.

Global network analysis of drug tolerance, mode of action and virulence in methicillin-resistant S. aureus

BACKGROUND

Staphylococcus aureus is a major human pathogen and strains resistant to existing treatments continue to emerge. Development of novel treatments is therefore important. Antimicrobial peptides represent a source of potential novel antibiotics to combat resistant bacteria such as Methicillin-Resistant Staphylococcus aureus (MRSA). A promising antimicrobial peptide is ranalexin, which has potent activity against Gram-positive bacteria, and particularly S. aureus. Understanding mode of action is a key component of drug discovery and network biology approaches enable a global, integrated view of microbial physiology, including mechanisms of antibiotic killing. We developed a systems-wide functional association network approach to integrate proteome and transcriptome profiles, enabling study of drug resistance and mode of action.

RESULTS

The functional association network was constructed by Bayesian logistic regression, providing a framework for identification of antimicrobial peptide (ranalexin) response modules from S. aureus MRSA-252 transcriptome and proteome profiling. These signatures of ranalexin treatment revealed multiple killing mechanisms, including cell wall activity. Cell wall effects were supported by gene disruption and osmotic fragility experiments. Furthermore, twenty-two novel virulence factors were inferred, while the VraRS two-component system and PhoU-mediated persister formation were implicated in MRSA tolerance to cationic antimicrobial peptides.

CONCLUSIONS

This work demonstrates a powerful integrative approach to study drug resistance and mode of action. Our findings are informative to the development of novel therapeutic strategies against Staphylococcus aureus and particularly MRSA.

Genomic variations define divergence of water/wildlife-associated Campylobacter jejuni niche specialists from common clonal complexes

Although the major food-borne pathogen Campylobacter jejuni has been isolated from diverse animal, human and environmental sources, our knowledge of genomic diversity in C. jejuni is based exclusively on human or human food-chain-associated isolates. Studies employing multilocus sequence typing have indicated that some clonal complexes are more commonly associated with particular sources. Using comparative genomic hybridization on a collection of 80 isolates representing diverse sources and clonal complexes, we identified a separate clade comprising a group of water/wildlife isolates of C. jejuni with multilocus sequence types uncharacteristic of human food-chain-associated isolates. By genome sequencing one representative of this diverse group (C. jejuni 1336), and a representative of the bank-vole niche specialist ST-3704 (C. jejuni 414), we identified deletions of genomic regions normally carried by human food-chain-associated C. jejuni. Several of the deleted regions included genes implicated in chicken colonization or in virulence. Novel genomic insertions contributing to the accessory genomes of strains 1336 and 414 were identified. Comparative analysis using PCR assays indicated that novel regions were common but not ubiquitous among the water/wildlife group of isolates, indicating further genomic diversity among this group, whereas all ST-3704 isolates carried the same novel accessory regions. While strain 1336 was able to colonize chicks, strain 414 was not, suggesting that regions specifically absent from the genome of strain 414 may play an important role in this common route of Campylobacter infection of humans. We suggest that the genomic divergence observed constitutes evidence of adaptation leading to niche specialization.

Evolutionary genomics of Staphylococcus aureus reveals insights into the origin and molecular basis of ruminant host adaptation

Phenotypic biotyping has traditionally been used to differentiate bacteria occupying distinct ecological niches such as host species. For example, the capacity of Staphylococcus aureus from sheep to coagulate ruminant plasma, reported over 60 years ago, led to the description of small ruminant and bovine S. aureus ecovars. The great majority of small ruminant isolates are represented by a single, widespread clonal complex (CC133) of S. aureus, but its evolutionary origin and the molecular basis for its host tropism remain unknown. Here, we provide evidence that the CC133 clone evolved as the result of a human to ruminant host jump followed by adaptive genome diversification. Comparative whole-genome sequencing revealed molecular evidence for host adaptation including gene decay and diversification of proteins involved in host–pathogen interactions. Importantly, several novel mobile genetic elements encoding virulence proteins with attenuated or enhanced activity in ruminants were widely distributed in CC133 isolates, suggesting a key role in its host-specific interactions. To investigate this further, we examined the activity of a novel staphylococcal pathogenicity island (SaPIov2) found in the great majority of CC133 isolates which encodes a variant of the chromosomally encoded von Willebrand-binding protein (vWbp^Sov2), previously demonstrated to have coagulase activity for human plasma. Remarkably, we discovered that SaPIov2 confers the ability to coagulate ruminant plasma suggesting an important role in ruminant disease pathogenesis and revealing the origin of a defining phenotype of the classical S. aureus biotyping scheme. Taken together, these data provide broad new insights into the origin and molecular basis of S. aureus ruminant host specificity.

Genetic diversity in CC398 methicillin-resistant Staphylococcus aureus isolates of different geographical origin

Staphylococcus aureus of sequence type 398 has emerged in Europe, North America and Asia, and has typically been associated with livestock and their human contacts. We analysed two Panton-Valentine leukocidin (PVL)-negative t034-ST398 isolates from humans in contact with pigs and two t034-ST398 PVL-positive isolates from two unrelated, adopted Chinese children, using multistrain microarrays to determine genomic variability between the two sets of isolates. The ST398 isolates clearly belong to the same lineage when compared to other clonal lineages. However, the four isolates cluster into two distinct groups corresponding to differences in epidemiology based on mobile genetic elements and resistance patterns, suggesting that the two groups are epidemiologically distinct.

Novel symmetric and asymmetric DNA scission determinants for Streptococcus pneumoniae topoisomerase IV and gyrase are clustered at the DNA breakage site

Topoisomerase (topo) IV and gyrase are bacterial type IIA DNA topoisomerases essential for DNA replication and chromosome segregation that act via a transient double-stranded DNA break involving a covalent enzyme-DNA "cleavage complex." Despite their mechanistic importance, the DNA breakage determinants are not understood for any bacterial type II enzyme. We investigated DNA cleavage by Streptococcus pneumoniae topo IV and gyrase stabilized by gemifloxacin and other antipneumococcal fluoroquinolones. Topo IV and gyrase induce distinct but overlapping repertoires of double-strand DNA breakage sites that were essentially identical for seven different quinolones and were augmented (in intensity) by positive or negative supercoiling. Sequence analysis of 180 topo IV and 126 gyrase sites promoted by gemifloxacin on pneumococcal DNA revealed the respective consensus sequences: G(G/c)(A/t)A*GNNCt(T/a)N(C/a) and GN4G(G/c)(A/c)G*GNNCtTN(C/a) (preferred bases are underlined; disfavored bases are in small capitals; N indicates no preference; and asterisk indicates DNA scission between -1 and +1 positions). Both enzymes show strong preferences for bases clustered symmetrically around the DNA scission site, i.e. +1G/+4C, -4G/+8C, and particularly the novel -2A/+6T, but with no preference at +2/+3 within the staggered 4-bp overhang. Asymmetric elements include -3G and several unfavored bases. These cleavage preferences, the first for Gram-positive type IIA topoisomerases, differ markedly from those reported for Escherichia coli topo IV (consensus (A/G)*T/A) and gyrase, which are based on fewer sites. However, both pneumococcal enzymes cleaved an E. coli gyrase site suggesting overlap in gyrase determinants. We propose a model for the cleavage complex of topo IV/gyrase that accommodates the unique -2A/+6T and other preferences.

p53 Elevation in Relation to Levels and Cytotoxicity of Mono- and Bifunctional Melphalan-DNA Adducts

We tested the hypothesis that bifunctional DNA adducts formed by a nitrogen mustard-based anticancer drug were more efficient than monofunctional adducts at causing elevation of p53, consistent with the difference in cytotoxicity. Human leukemia cell line ML-1 was exposed for 1 h to melphalan or its monofunctional derivative monohydroxymelphalan. Levels of DNA adducts, measured by specific immunoassay, were linearly related to the concentration of alkylating agent. Monohydroxymelphalan formed twice as many adducts as did equal concentrations of melphalan. After the removal of the alkylating agent, adduct levels were maintained or increased slightly up to 8 h and then decreased by 27 to 44% by 24 h. Alkaline elution analyses confirmed the absence of detectable DNA interstrand cross-links in cells exposed to monohydroxymelphalan. DNA single-strand breaks were detected after monohydroxymelphalan but not after melphalan. Levels of p53 were quantified by sensitive fluorogenic enzyme-linked immunosorbent assay at intervals up to 24 h after exposure of cells to various concentrations of melphalan and monohydroxymelphalan. The level of initially formed DNA adducts needed to cause elevation of p53 from a baseline level of 0.5 ng/mg total protein to 2 ng/mg was 5- to 8-fold higher for monohydroxymelphalan than melphalan. The concentrations of melphalan and monohydroxymelphalan (+/-S.D.) causing 50% growth inhibition were 1.2 +/- 0.4 and 28.1 +/- 1.6 microg/ml, respectively, a 23-fold difference. The adduct levels induced by these exposures were 9.3 and 420 nmol/g DNA for melphalan and monohydroxymelphalan, respectively, a 45-fold difference, which is considerably greater than the difference in efficacy at elevating p53.

Ciprofloxacin dimers target gyrase in Streptococcus pneumoniae

We have examined the antipneumococcal activities of novel quinolone dimers in which ciprofloxacin was tethered to itself or to pipemidic acid by linkage of C-7 piperazinyl rings. Symmetric 2,6-lutidinyl- and trans-butenyl-linked ciprofloxacin dimers (dimers 1 and 2, respectively) and a pipemidic acid-ciprofloxacin dimer (dimer 3) had activities against Streptococcus pneumoniae strain 7785 that were comparable to that of ciprofloxacin, i.e., MICs of 2, 1, and 4 to 8 microg/ml versus an MIC of 1 to 2 microg/ml, respectively. Surprisingly, unlike ciprofloxacin (which targets topoisomerase IV), several lines of evidence revealed that the dimers act through gyrase in S. pneumoniae. First, ciprofloxacin-resistant parC mutants of strain 7785 remained susceptible to dimers 1 to 3, whereas a gyrA mutation conferred a four- to eightfold increase in the dimer MIC but had little effect on ciprofloxacin activity. Second, dimer 1 selected first-step gyrA (S81Y or S81F) mutants (MICs, 8 to 16 microg/ml) that carried wild-type topoisomerase IV parE-parC genes. Third, dimers 1 and 2 promoted comparable DNA cleavage by S. pneumoniae gyrase and topoisomerase IV, whereas ciprofloxacin-mediated cleavage was 10-fold more efficient with topoisomerase IV than with gyrase. Fourth, the GyrA S81F and ParC S79F enzymes were resistant to dimers, confirming that the resistance phenotype is largely silent in parC mutants. Although a dimer molecule could bind very tightly by bridging quinolone binding sites in the enzyme-DNA complex, the greater potency of ciprofloxacin against gyrase and topoisomerase IV suggests that dimers 1 to 3 bind in a monomeric fashion. The bulky C-7 side chain may explain dimer targeting of gyrase and activity against efflux mutants. Tethered quinolones have potential as mechanistic tools and as novel antimicrobial agents.

Cleavable-complex formation by wild-type and quinolone-resistant Streptococcus pneumoniae type II topoisomerases mediated by gemifloxacin and other fluoroquinolones

Gemifloxacin is a recently developed fluoroquinolone with potent activity against Streptococcus pneumoniae. We show that the drug is more active than moxifloxacin, gatifloxacin, levofloxacin, and ciprofloxacin against S. pneumoniae strain 7785 (MICs, 0.03 to 0.06 microg/ml versus 0.25, 0.25, 1, and 1 to 2 microg/ml, respectively) and against isogenic quinolone-resistant gyrA-parC mutants (MICs, 0.5 to 1 microg/ml versus 2 to 4, 2 to 4, 16 to 32, and 64 microg/ml, respectively). Gemifloxacin was also the most potent agent against purified S. pneumoniae DNA gyrase and topoisomerase IV in both catalytic inhibition and DNA cleavage assays. The drug concentrations that inhibited DNA supercoiling or DNA decatenation by 50% (IC(50)s) were 5 to 10 and 2.5 to 5.0 microM, respectively. Ciprofloxacin and levofloxacin were some four- to eightfold less active against either enzyme; moxifloxacin and gatifloxacin showed intermediate activities. In assays of drug-mediated DNA cleavage by gyrase and topoisomerase IV, the same order of potency was seen: gemifloxacin > moxifloxacin > gatifloxacin > levofloxacin approximately ciprofloxacin. For gemifloxacin, the drug concentrations that caused 25% linearization of the input DNA by gyrase and topoisomerase IV were 2.5 and 0.1 to 0.3 microM, respectively; these values were 4-fold and 8- to 25-fold lower than those for moxifloxacin, respectively. Each drug induced DNA cleavage by gyrase at the same spectrum of sites but with different patterns of intensity. Finally, for enzymes reconstituted with quinolone-resistant GyrA S81F or ParC S79F subunits, although cleavable-complex formation was reduced by at least 8- to 16-fold for all the quinolones tested, gemifloxacin was the most effective; e.g., it was 4- to 16-fold more active than the other drugs against toposiomerase IV with the ParC S79F mutation. It appears that the greater potency of gemifloxacin against both wild-type and quinolone-resistant S. pneumoniae strains arises from enhanced stabilization of gyrase and topoisomerase IV complexes on DNA.

DES action in the thymus: inhibition of cell proliferation and genetic variation

Many tissues, including the thymus, represent direct targets of estrogen action. In contrast to many estrogen responsive tissues, the thymus undergoes a profound atrophy in response to elevated levels of estrogens. The mechanism of estrogen-induced atrophy in the thymus is unknown; however, it appears not to involve massive thymocyte apoptosis. Here, we demonstrate that the estrogen diethylstilbestrol (DES) inhibits cell proliferation within the thymic cortex, the primary site of thymocyte proliferation. Unlike glucocorticoid action, the effect of DES on thymocyte proliferation does not appear to be mediated by direct down regulation of cyclin D3. We also demonstrate for the first time that rat strains vary in their sensitivity to DES-induced thymic atrophy. This sensitivity correlates with the ability of DES to inhibit cell proliferation in the thymus. These data suggest that genetic factors may regulate estrogen action within this tissue by affecting estrogen responsive pathways that control cell proliferation.

The Mom1AKR intestinal tumor resistance region consists of Pla2g2a and a locus distal to D4Mit64

The Mom1 (Modifier of Min-1) region of distal chromosome 4 was identified during a screen for polymorphic modifiers of intestinal tumorigenesis in ApcMin/+ mice. Here, we demonstrate that the Mom1AKR allele consists of two genetic components. These include the secretory phospholipase Pla2g2a, whose candidacy as a Mom1 resistance modifier has now been tested with several transgenic lines. A second region, distal to Pla2g2a, has also been identified using fine structure recombinants. Pla2g2aAKR transgenic mice demonstrate a modest resistance to tumorigenesis in the small intestine and a very robust resistance in the large intestine. Moreover, the tumor resistance in the colon of Pla2g2aAKR animals is dosage-dependent, a finding that is consistent with our observation that Pla2g2a is expressed in goblet cells. By contrast, mice carrying the distal Mom1 modifier demonstrate a modest tumor resistance that is confined to the small intestine. Thus, the phenotypes of these two modifier loci are complementary, both in their quantitative and regional effects. The additive effects and tight linkage of these modifiers may have been necessary for the initial identification of the Mom1 region.

A monofunctional derivative of melphalan: preparation, DNA alkylation products, and determination of the specificity of monoclonal antibodies that recognize melphalan-DNA adducts

Bifunctional alkylating agents, such as those based on nitrogen mustard, form important parts of many anti-cancer chemotherapy protocols and are responsible for increased incidences of secondary tumors in successfully treated patients. These drugs generally form a majority of monofunctional DNA adducts, although the bifunctional adducts appear to be necessary for their powerful cytotoxic and antitumor effects. The relative importance of bifunctional as opposed to monofunctional adducts in the varied biological consequences of drug exposure has not been studied in detail, particularly in relation to the role and specificity of biochemical responses to therapy-related DNA damage. A simple method is described for the preparation of useful quantities of a pure monofunctional derivative of the nitrogen mustard-based drug melphalan. Monohydroxymelphalan was prepared by partial hydrolysis, purified by reversed phase chromatography, and characterized by MS, NMR, and HPLC. Contamination with melphalan was </=0.2%. The heat labile DNA base adducts formed by monohydroxymelphalan were shown to contain undetectable levels of cross-linked species. The ratio of adenine to guanine adducts was 0.62, similar to the equivalent ratio for melphalan. The sequence-dependent pattern of alkylation of purified DNA was indistinguishable from that of melphalan, but required a higher dose to achieve comparable extents of reaction. The specificities of two monoclonal antibodies that recognize melphalan-DNA adducts were investigated using DNA alkylated with [3H]monohydroxymelphalan. Adducts on this DNA showed similar immunoreactivities to adducts formed by melphalan. This shows clearly that neither antibody was specific for cross-linked adducts and that it is therefore possible to quantify adducts formed by both monohydroxymelphalan and melphalan with high sensitivities. The availability of monohydroxymelphalan in addition to melphalan, together with sensitive immunoassays for adducts on extracted DNA and in individual cells, constitutes a useful system for investigating cellular responses to the DNA modifications formed by a clinically relevant drug.

The impact of National Cancer Institute training on clinical tobacco use cessation services by oral health teams

The authors surveyed participants in a National Cancer Institute, or NCI, training program that provides brief tobacco cessation services. They found significant improvements in the frequency with which practitioners ask patients about tobacco use and assist patients in stopping tobacco use. Improvements also were found in the participants' level of confidence and preparedness to help patients quit. Despite some limitations, the NCI training was shown to be an effective program for the oral health care team.

Analysis of the Mom1 modifier of intestinal neoplasia in mice

Although the methodology for mapping genes controlling susceptibility to tumor development in mice is becoming well established, it remains a formidable challenge to move from linkage to locus. Positional cloning, now commonly used in the identification of loci affecting a qualitative phenotype, has yet to be successfully applied to quantitative trait loci. This study describes the application of candidate gene testing, a method complementary to positional cloning. The method has been applied to evaluate candidates for the quantitative trait locus, Mom1, which modifies the susceptibility of ApcMin/+ mice to spontaneous intestinal tumor development. The authors also discuss the further testing of one candidate, the phospholipase gene Pla2g2a, by transgenesis. Finally, studies on the mode of action of Mom1 are discussed in light of the evidence that Mom1 encodes this secretory phospholipase.

The intestinal epithelium and its neoplasms: genetic, cellular and tissue interactions

The Min (multiple intestinal neoplasia) strain of the laboratory mouse and its derivatives permit the fundamental study of factors that regulate the transition between normal and neoplastic growth. A gene of central importance in mediating these alternative patterns of growth is Apc, the mouse homologue of the human adenomatous polyposis coli (APC) gene. When adenomas form in the Min mouse, both copies of the Apc gene must be inactivated. One copy is mutated by the nonsense Apc allele carried in heterozygous form in this strain. The other copy can be silenced by any of several mechanisms. These range from loss of the homologue bearing the wild-type Apc allele; to interstitial deletions surrounding the wild-type allele; to intragenic mutation, including nonsense alleles; and finally, to a reduction in expression of the locus, perhaps owing to mutation in a regulatory locus. Each of these proposed mechanisms may constitute a two-hit genetic process as initially posited by Knudson; however, apparently the two hits could involve either a single locus or two loci. The kinetic order for the transition to adenoma may be still higher than two, if polyclonal adenomas require stronger interactions than passive fusion. The severity of the intestinal neoplastic phenotype of the Min mouse is strongly dependent upon loci other than Apc. One of these, Mom1, has now been rigorously identified at the molecular level as encoding an active resistance conferred by a secretory phospholipase. Mom1 acts locally within a crypt lineage, not systemically. Within the crypt lineage, however, its action seems to be non-autonomous: when tumours arise in Mom1 heterozygotes, the active resistance allele is maintained in the tumour (MOH or maintenance of heterozygosity). Indeed, the secretory phospholipase is synthesized by post-mitotic Paneth cells, not by the proliferative cells that presumably generate the tumour. An analysis of autonomy of modifier gene action in chimeric mice deserves detailed attention both to the number of genetic factors for which an animal is chimeric and to the clonal structure of the tissue in question. Beyond Mom1, other loci can strongly modify the severity of the Min phenotype. An emergent challenge is to find ways to identify the full set of genes that interact with the intestinal cancer predisposition of the Min mouse strain. With such a set, one can then work, using contemporary mouse genetics, to identify the molecular, cellular and organismal strategies that integrate their functions. Finally, with appropriately phenotyped human families, one can investigate by a candidate approach which modifying factors influence the epidemiology of human colon cancer. Even if a candidate modifier does not explain any of the genetic epidemiology of colon cancer in human populations, modifier activities discovered by mouse genetics provide candidates for chemopreventive and/or therapeutic modalities in the human.

Polyclonal structure of intestinal adenomas in ApcMin/+ mice with concomitant loss of Apc+ from all tumor lineages

When tumors form in intestinal epithelia, it is important to know whether they involve single initiated somatic clones. Advanced carcinomas in humans and mice are known to be monoclonal. However, earlier stages of tumorigenesis may instead involve an interaction between cells that belong to separate somatic clones within the epithelium. The clonality of early tumors has been investigated in mice with an inherited predisposition to intestinal tumors. Analysis of Min (multiple intestinal neoplasia) mice chimeric for a ubiquitously expressed cell lineage marker revealed that normal intestinal crypts are monoclonal, but intestinal adenomas frequently have a polyclonal structure, presenting even when very small as single, focal adenomas composed of at least two somatic lineages. Furthermore, within these polyclonal adenomas, all tumor lineages frequently lose the wild-type Apc allele. These observations can be interpreted by several models for clonal interaction within the epithelium, ranging from passive fusion within regions of high neoplastic potential to a requirement for active clonal cooperation.

Localized gene action controlling intestinal neoplasia in mice

Mice heterozygous for the ApcMin (Min) mutation develop adenomas throughout the intestinal tract. Apc is believed to be involved in cell migration, adhesion, and polarity. Adenoma multiplicity and growth rate are modulated by an unlinked modifier locus, Mom1. The secretory phospholipase Pla2g2a is a candidate for Mom1. Here, we investigate the range of action of Apc and Mom1. Analysis of chimeric Min mice indicates that the actions of both Apc and Mom1 are localized within the cell lineage that gives rise to intestinal tumors.

Intestinal neoplasia in the ApcMin mouse: independence from the microbial and natural killer (beige locus) status

We have tested the hypothesis that enteric bacteria are necessary for formation of intestinal adenomas in C57BL/6-ApcMin/+ mouse. Germ-free mice developed 2-fold fewer adenomas than conventional controls in the medial small intestine (7.3 versus 14.9; P < 0.003), but there were no significant differences in the rest of the intestinal tract. We conclude that microbial status does not strongly alter the adenoma phenotype in this mouse model of familial adenomatous polyposis. In parallel, we have found that C57BL/6-ApcMin/+ mice mutated at the beige locus, which controls natural killer activity, are also unaltered in adenoma multiplicity.

Genetic evaluation of candidate genes for the Mom1 modifier of intestinal neoplasia in mice

As genetic mapping of quantitative trait loci (QTL) becomes routine, the challenge is to identify the underlying genes. This paper develops rigorous genetic tests for evaluation of candidate genes for a QTL, involving determination of allelic status in inbred strains and fine-structure genetic mapping. For the Mom1 modifier of intestinal adenomas caused by ApcMin, these tests are used to evaluate two candidate genes: Pla2g2a, a secretory phospholipase, and Rap1GAP, a GTPase activating protein. Rap1GAP passes the first test but is excluded by a single fine-structure recombinant. Pla2g2a passes both tests and is a strong candidate for Mom1. Significantly, we also find that ApcMin-induced adenomas remain heterozygous for the Mom1 region, consistent with Mom1 acting outside the tumor lineage and encoding a secreted product.

Current intra-aortic balloon pump practice issues. Survey results

Patient care delivery has changed or has at least begun to change throughout institutions nationwide. Those who once regarded theory as a formulation for patient outcome have rendered it inefficient; as the practice of balloon pumping has expanded, many important questions have been raised surrounding the basis for procedures involving IABP. Nursing guidelines for correct IABP procedures are theoretically based procedures. Although it is influential, theory-based practice has proven to be an inefficient means for formulating current practice standards. The Ahern Gould and Stark Current Practice Survey exemplifies the uncertainties that surround the practice of IABP. The nationwide search for scientifically based IABP methods is realized as those surveyed present numerous questions, giving rise to clinical research directions for IABP practitioners.

Mom1 is a semi-dominant modifier of intestinal adenoma size and multiplicity in Min/+ mice

The intestinal tumor multiplicity in mice heterozygous for ApcMin is strongly modulated by genetic background. On the sensitive C57BL/6J (B6) background, mice develop large numbers of intestinal adenomas. The AKR/J (AKR) strain carries alleles that correlate with a strong reduction in tumor multiplicity. To study the effect of one of these modifiers, Mom1, we have generated a mouse line in which the AKR allele of Mom1 is carried on the sensitive B6 genetic background. This strain was produced by using a marker-assisted selection method to eliminate unlinked AKR alleles more rapidly. The application and efficiency of this method are discussed. We used this strain to determine that Mom1 affects both tumor multiplicity and tumor size in a semi-dominant fashion.

Action of Min and Mom1 on neoplasia in ectopic intestinal grafts

Mice heterozygous for Min, a mutant allele of Apc, develop adenomas throughout the intestinal tract. Tumor multiplicity in Min mice is influenced by genetic modifier loci. Previously, we mapped one of these modifier loci, Mom1, to distal mouse chromosome 4. Mom1 is a semidominant modifier of both tumor size and multiplicity in Min mice. Recent evidence suggests that Mom1 may encode a secretory phospholipase, Pla2g2a. Pla2g2a is expressed in a variety of cell types and seems to be involved in inflammatory responses and bacterial defense mechanisms. Here, we determine whether Min and Mom1 act in a tissue-autonomous fashion using ectopic intestinal isografts. Within the small intestinal grafts, both Min and Mom1 act in a tissue-autonomous manner. There is no evidence that either Min or Mom1 has a systemic effect on tumor development. However, within the colonic grafts, the Min phenotype does not appear to be autonomous; the development of colonic tumors in Min mice seems dependent on factors beyond the Min genotype of the colonic epithelium. Micro-environmental factors, such as digestive secretions, dietary components, or intestinal flora, may be critical factors contributing to the development of Min-induced colonic tumors. However, these factors are not required for the action of Min or Mom1 within the small intestine.

Manipulation of the mouse germline in the study of Min-induced neoplasia

The Min mouse, generated by random germline mutagenesis, carries a mutation in the mouse homolog of APC and is a model of inherited human intestinal tumorigenesis. To identify other genes in the pathway(s) of intestinal tumorigenesis, genes that modify the Min phenotype have been sought. Several have been identified, including Mom1 and the genes for the 5-cytosine DNA methyltransferase and the DNA mismatch repair factor Msh2. Min-dependent tumorigenesis also occurs in mammary glands, the pancreas, and the body wall. The Min mouse has therefore become a model for tumorigenesis in a variety of organs. Identifying modifiers of its phenotype will help in piecing together the pathways of tumorigenesis in each of these tissues.

Paradoxical effect of thalidomide prophylaxis on chronic graft-vs.-host disease

Thalidomide has been reported to be an effective agent for the treatment of chronic graft-vs.-host disease (GVHD). To determine its efficacy as a prophylactic agent for the prevention of chronic GVHD, a prospective randomized double-blind study was performed. A total of 59 patients were randomized to receive either placebo or thalidomide (200 mg orally twice a day) beginning 80 days after allogeneic bone marrow transplantation (BMT). Fifty-four evaluable patients were analyzed, 26 received placebo, and 28 received thalidomide. The characteristics of patients were well-balanced between the two groups. Following the first interim analysis conducted by the Data Safety Monitoring Board using an intent-to-treat approach, a statistically significant difference in the incidence of chronic GVHD was found. Patients receiving thalidomide developed chronic GVHD more often than patients receiving placebo (p = 0.06). Moreover, an apparent overall survival advantage was noted for patients receiving placebo compared to those receiving thalidomide (p = 0.006). Adjustment for possible confounding factors did not eliminate these negative effects of thalidomide. These results demonstrate that while thalidomide is an effective agent for the therapy of chronic GVHD, its use at the doses administered for the prophylaxis of chronic GVHD resulted in a paradoxical outcome with a higher incidence of chronic GVHD and a lower overall survival. We conclude that the early use of thalidomide results in a shift in the balance between GVHD and induction of tolerance. These data demonstrate again the importance of phase III double-blind controlled randomized studies.

Homozygosity for the Min allele of Apc results in disruption of mouse development prior to gastrulation

Mutation of the APC (adenomatous polyposis coli) gene is an early event in colon tumor development in humans. Mice carrying Min (multiple intestinal neoplasia), a mutant allele of Apc, develop intestinal and mammary tumors as adults. To study the role of the Apc gene in development, we have investigated the phenotype of embryos homozygous for ApcMin (Min). Development of the primitive ectoderm fails prior to gastrulation in homozygous Min embryos. By midgestation, the presumed homozygotes consist of a mass of trophoblast giant cells with an additional cluster of much smaller embryonic cells. These results indicate that functional Apc is required for normal growth of inner cell mass derivatives.

ApcMin: a mouse model for intestinal and mammary tumorigenesis

Min (multiple intestinal neoplasia) is a mutant allele of the murine Apc (adenomatous polyposis coli) locus, encoding a nonsense mutation at codon 850. Like humans with germline mutations in APC, Min/+ mice are predisposed to intestinal adenoma formation. The number of adenomas is influenced by modifier loci carried by different inbred strains. One modifier locus, Mom-1 (modifier of Min-1), maps to distal chromosome 4. Intestinal tumours from both B6 (C57BL/6J) and hybrid Min/+ mice show extensive loss of the wild-type allele at Apc. B6 Min/+ female mice are predisposed to spontaneous mammary tumours. The incidence of both intestinal and mammary tumours can be increased in an age-specific manner by treatment with ethylnitrosourea (ENU). Min mice provide a good animal model for studying the role of Apc and interacting genes in the initiation and progression of intestinal and mammary tumorigenesis.

Prenatal drug education in public and private schools of Nebraska

Substance abuse during pregnancy continues to be a serious health problem in the United States. Hazards associated with the use of alcohol, tobacco, and other drugs by pregnant women have been documented. The extent to which prenatal drug education is included in school health education has not been addressed. This survey determined the nature and extent of prenatal drug education being conducted by Nebraska school teachers in health-related fields. Educators in public and private schools who teach health-related courses were surveyed. Respondents indicated prenatal drug education is being addressed in a variety of courses. Amount of time devoted to the topic was 2.68 hours overall. Problems associated with providing prenatal drug education included inadequate teacher knowledge and training, lack of appropriate materials, and time limitations in the curriculum. Implications for comprehensive school health education are identified.