A One Health Perspective on Salmonella enterica Serovar Infantis, an Emerging Human Multidrug-Resistant Pathogen

Salmonella enterica serovar Infantis presents an ever-increasing threat to public health because of its spread throughout many countries and association with high levels of antimicrobial resistance (AMR). We analyzed whole-genome sequences of 5,284 Salmonella Infantis strains from 74 countries, isolated during 1989-2020 from a wide variety of human, animal, and food sources, to compare genetic phylogeny, AMR determinants, and plasmid presence. The global Salmonella Infantis population structure diverged into 3 clusters: a North American cluster, a European cluster, and a global cluster. The levels of AMR varied by Salmonella Infantis cluster and by isolation source; 73% of poultry isolates were multidrug resistant, compared with 35% of human isolates. This finding correlated with the presence of the pESI megaplasmid; 71% of poultry isolates contained pESI, compared with 32% of human isolates. This study provides key information for public health teams engaged in reducing the spread of this pathogen.

COVID-19 therapeutics: stewardship in England and considerations for antimicrobial resistance

The COVID-19 pandemic saw unprecedented resources and funds driven into research for the development, and subsequent rapid distribution, of vaccines, diagnostics and directly acting antivirals (DAAs). DAAs have undeniably prevented progression and life-threatening conditions in patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. However, there are concerns of antimicrobial resistance (AMR), antiviral resistance specifically, for DAAs. To preserve activity of DAAs for COVID-19 therapy, as well as detect possible mutations conferring resistance, antimicrobial stewardship and surveillance were rapidly implemented in England. This paper expands on the ubiquitous ongoing public health activities carried out in England, including epidemiologic, virologic and genomic surveillance, to support the stewardship of DAAs and assess the deployment, safety, effectiveness and resistance potential of these novel and repurposed therapeutics.

A molnupiravir-associated mutational signature in global SARS-CoV-2 genomes

Molnupiravir, an antiviral medication widely used against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), acts by inducing mutations in the virus genome during replication. Most random mutations are likely to be deleterious to the virus and many will be lethal; thus, molnupiravir-induced elevated mutation rates reduce viral load1,2. However, if some patients treated with molnupiravir do not fully clear the SARS-CoV-2 infections, there could be the potential for onward transmission of molnupiravir-mutated viruses. Here we show that SARS-CoV-2 sequencing databases contain extensive evidence of molnupiravir mutagenesis. Using a systematic approach, we find that a specific class of long phylogenetic branches, distinguished by a high proportion of G-to-A and C-to-T mutations, are found almost exclusively in sequences from 2022, after the introduction of molnupiravir treatment, and in countries and age groups with widespread use of the drug. We identify a mutational spectrum, with preferred nucleotide contexts, from viruses in patients known to have been treated with molnupiravir and show that its signature matches that seen in these long branches, in some cases with onward transmission of molnupiravir-derived lineages. Finally, we analyse treatment records to confirm a direct association between these high G-to-A branches and the use of molnupiravir.

Generation of SARS-CoV-2 escape mutations by monoclonal antibody therapy

COVID-19 patients at risk of severe disease may be treated with neutralising monoclonal antibodies (mAbs). To minimise virus escape from neutralisation these are administered as combinations e.g. casirivimab+imdevimab or, for antibodies targeting relatively conserved regions, individually e.g. sotrovimab. Unprecedented genomic surveillance of SARS-CoV-2 in the UK has enabled a genome-first approach to detect emerging drug resistance in Delta and Omicron cases treated with casirivimab+imdevimab and sotrovimab respectively. Mutations occur within the antibody epitopes and for casirivimab+imdevimab multiple mutations are present on contiguous raw reads, simultaneously affecting both components. Using surface plasmon resonance and pseudoviral neutralisation assays we demonstrate these mutations reduce or completely abrogate antibody affinity and neutralising activity, suggesting they are driven by immune evasion. In addition, we show that some mutations also reduce the neutralising activity of vaccine-induced serum.

Characterization of a pESI-like plasmid and analysis of multidrug-resistant Salmonella enterica Infantis isolates in England and Wales

Salmonella enterica serovar Infantis is the fifth most common Salmonella serovar isolated in England and Wales. Epidemiological, genotyping and antimicrobial-resistance data for S. enterica Infantis isolates were used to analyse English and Welsh demographics over a 5 year period. Travel cases associated with S. enterica Infantis were mainly from Asia, followed by cases from Europe and North America. Since 2000, increasing numbers of S. enterica Infantis had multidrug resistance determinants harboured on a large plasmid termed ‘plasmid of emerging S. enterica Infantis’ (pESI). Between 2013 and 2018, 42 S. enterica Infantis isolates were isolated from humans and food that harboured resistance determinants to multiple antimicrobial classes present on a pESI-like plasmid, including extended-spectrum β-lactamases (ESBLs; bla_CTX-M-65). Nanopore sequencing of an ESBL-producing human S. enterica Infantis isolate indicated the presence of two regions on an IncFIB pESI-like plasmid harbouring multiple resistance genes. Phylogenetic analysis of the English and Welsh S. enterica Infantis population indicated that the majority of multidrug-resistant isolates harbouring the pESI-like plasmid belonged to a single clade maintained within the population. The bla_CTX-M-65 ESBL isolates first isolated in 2013 comprise a lineage within this clade, which was mainly associated with South America. Our data, therefore, show the emergence of a stable resistant clone that has been in circulation for some time in the human population in England and Wales, highlighting the necessity of monitoring resistance in this serovar.

Outbreak of Shiga toxin-producing Escherichia coli O157:H7 linked to raw drinking milk resolved by rapid application of advanced pathogen characterisation methods, England, August to October 2017

An outbreak of Shiga toxin-producing Escherichia coli (STEC) O157:H7 occurred on the Isle of Wight between August and October 2017. Of the seven cases linked to the outbreak, five were identified through the statutory notification process and two were identified through national surveillance of whole genome sequencing data. Enhanced surveillance questionnaires established a common link to a farm, and link to the likely food vehicle, raw drinking milk (RDM). Microbiological investigations, including PCR, identified the presence of STEC O157:H7 in samples of RDM. Analysis of core genome single nucleotide polymorphism (SNP) data of STEC O157:H7 from human stool specimens, animal faecal samples and RDM demonstrated a one SNP difference between isolates, and therefore close genetic relatedness. Control measures that were put in place included suspension of sales and recall of RDM, as well as restrictions on public access to parts of the farm. Successful integration of traditional epidemiological surveillance and advanced laboratory methods for the detection and characterisation of STEC O157:H7 from human, animal and environmental samples enabled prompt identification of the outbreak vehicle and provided evidence to support the outbreak control team’s decision-making, leading to implementation of effective control measures in a timely manner.

Concordance of SNP- and allele-based typing workflows in the context of a large-scale international Salmonella Enteritidis outbreak investigation

A large European multi-country Salmonella enterica serovar Enteritidis outbreak associated with Polish eggs was characterized by whole-genome sequencing (WGS)-based analysis, with various European institutes using different analysis workflows to identify isolates potentially related to the outbreak. The objective of our study was to compare the output of six of these different typing workflows (distance matrices of either SNP-based or allele-based workflows) in terms of cluster detection and concordance. To this end, we analysed a set of 180 isolates coming from confirmed and probable outbreak cases, which were representative of the genetic variation within the outbreak, supplemented with 22 unrelated contemporaneous S. enterica serovar Enteritidis isolates. Since the definition of a cluster cut-off based on genetic distance requires prior knowledge on the evolutionary processes that govern the bacterial populations in question, we used a variety of hierarchical clustering methods (single, average and complete) and selected the optimal number of clusters based on the consensus of the silhouette, Dunn2, and McClain-Rao internal validation indices. External validation was done by calculating the concordance with the WGS-based case definition (SNP-address) for this outbreak using the Fowlkes-Mallows index. Our analysis indicates that with complete-linkage hierarchical clustering combined with the optimal number of clusters, as defined by three internal validity indices, the six different allele- and SNP-based typing workflows generate clusters with similar compositions. Furthermore, we show that even in the absence of coordinated typing procedures, but by using an unsupervised machine learning methodology for cluster delineation, the various workflows that are currently in use by six European public-health authorities can identify concordant clusters of genetically related S. enterica serovar Enteritidis isolates; thus, providing public-health researchers with comparable tools for detection of infectious-disease outbreaks.

The characterization of mobile colistin resistance (mcr) genes among 33 000 Salmonella enterica genomes from routine public health surveillance in England

To establish the prevalence of mobile colistin resistance (mcr) genes amongst Salmonella enterica isolates obtained through public health surveillance in England (April 2014 to September 2017), 33 205 S. enterica genome sequences obtained from human, food, animal and environmental isolates were screened for the presence of mcr variants 1 to 8. The mcr-positive genomes were assembled, annotated and characterized according to plasmid type. Nanopore sequencing was performed on six selected isolates with putative novel plasmids, and phylogenetic analysis was used to provide an evolutionary context for the most commonly isolated clones. Fifty-two mcr-positive isolates were identified, of which 32 were positive for mcr-1, 19 for mcr-3 and 1 for mcr-5. The combination of Illumina and Nanopore sequencing identified three novel mcr-3 plasmids and one novel mcr-5 plasmid, as well as the presence of chromosomally integrated mcr-1 and mcr-3. Monophasic S. enterica serovar Typhimurium accounted for 27/52 (52 %) of the mcr-positive isolates, with the majority clustering in clades associated with travel to Southeast Asia. Isolates in these clades were associated with a specific plasmid range and an additional extended-spectrum beta-lactamase genotype. Routine whole-genome sequencing for public health surveillance provides an effective screen for novel and emerging antimicrobial determinants, including mcr. Complementary long-read technologies elucidated the genomic context of resistance determinants, offering insights into plasmid dissemination and linkage to other resistance genes.

The Transformation of Reference Microbiology Methods and Surveillance for Salmonella With the Use of Whole Genome Sequencing in England and Wales

The use of whole genome sequencing (WGS) as a method for supporting outbreak investigations, studying Salmonella microbial populations and improving understanding of pathogenicity has been well-described (1–3). However, performing WGS on a discrete dataset does not pose the same challenges as implementing WGS as a routine, reference microbiology service for public health surveillance. Challenges include translating WGS data into a useable format for laboratory reporting, clinical case management, Salmonella surveillance, and outbreak investigation as well as meeting the requirement to communicate that information in an understandable and universal language for clinical and public health action. Public Health England have been routinely sequencing all referred presumptive Salmonella isolates since 2014 which has transformed our approach to reference microbiology and surveillance. Here we describe an overview of the integrated methods for cross-disciplinary working, describe the challenges and provide a perspective on how WGS has impacted the laboratory and surveillance processes in England and Wales.

Informal genomic surveillance of regional distribution of Salmonella Typhi genotypes and antimicrobial resistance via returning travellers

Salmonella enterica serovar Typhi (S. Typhi) is the causative agent of typhoid fever, a systemic human infection with a burden exceeding 20 million cases each year that occurs disproportionately among children in low and middle income countries. Antimicrobial therapy is the mainstay for treatment, but resistance to multiple agents is common. Here we report genotypes and antimicrobial resistance (AMR) determinants detected from routine whole-genome sequencing (WGS) of 533 S. Typhi isolates referred to Public Health England between April 2014 and March 2017, 488 (92%) of which had accompanying patient travel information obtained via an enhanced surveillance questionnaire. The majority of cases involved S. Typhi 4.3.1 (H58) linked with travel to South Asia (59%). Travel to East and West Africa were associated with genotypes 4.3.1 and 3.3.1, respectively. Point mutations in the quinolone resistance determining region (QRDR), associated with reduced susceptibility to fluoroquinolones, were very common (85% of all cases) but the frequency varied significantly by region of travel: 95% in South Asia, 43% in East Africa, 27% in West Africa. QRDR triple mutants, resistant to ciprofloxacin, were restricted to 4.3.1 lineage II and associated with travel to India, accounting for 23% of cases reporting travel to the country. Overall 24% of isolates were MDR, however the frequency varied significantly by region and country of travel: 27% in West Africa, 52% in East Africa, 55% in Pakistan, 24% in Bangladesh, 3% in India. MDR determinants were plasmid-borne (IncHI1 PST2 plasmids) in S. Typhi 3.1.1 linked to West Africa, but in all other regions MDR was chromosomally integrated in 4.3.1 lineage I. We propose that routine WGS data from travel-associated cases in industrialised countries could serve as informal sentinel AMR genomic surveillance data for countries where WGS is not available or routinely performed.

Our data demonstrate how routine WGS data produced by Public Health England can be further mined for informal passive surveillance of Salmonella Typhi circulating in different geographical regions where typhoid is endemic. We have shown the public health utility of a simplified approach to WGS reporting based on the GenoTyphi genotyping framework and nomenclature, which doesn’t require the generation of a phylogenetic tree or other phylogenetic analysis. These approaches yielded results consistent with previously reported antimicrobial resistance (AMR) patterns of S. Typhi, including prevalence of multi-drug resistant (MDR) and fluoroquinolone resistance in different regions in association with different pathogen variants. These data provide a rationale and framework for the extraction and reporting of geographically stratified genotype and AMR data from public health labs in non-endemic countries. Prospective analysis and reporting of such data could potentially detect shifts in regional S. Typhi populations, such as replacement or spread of different subclades and the emergence and dissemination of MDR, fluoroquinolone resistant and/or extensively drug resistant S. Typhi, providing valuable data to inform typhoid control measures in low and middle income countries that are still building their genomics capacity.

Emergence of phylogenetically diverse and fluoroquinolone resistant Salmonella Enteritidis as a cause of invasive nontyphoidal Salmonella disease in Ghana

BACKGROUND

Salmonella enterica serovar Enteritidis is a cause of both poultry- and egg-associated enterocolitis globally and bloodstream-invasive nontyphoidal Salmonella (iNTS) disease in sub-Saharan Africa (sSA). Distinct, multi-drug resistant genotypes associated with iNTS disease in sSA have recently been described, often requiring treatment with fluoroquinolone antibiotics. In industrialised countries, antimicrobial use in poultry production has led to frequent fluoroquinolone resistance amongst globally prevalent enterocolitis-associated lineages.

METHODOLOGY/PRINCIPAL FINDINGS

Twenty seven S. Enteritidis isolates from patients with iNTS disease and two poultry isolates, collected between 2007 and 2015 in the Ashanti region of Ghana, were whole-genome sequenced. These isolates, notable for a high rate of diminished ciprofloxacin susceptibility (DCS), were placed in the phyletic context of 1,067 sequences from the Public Health England (PHE) S. Enteritidis genome database to understand whether DCS was associated with African or globally-circulating clades of S. Enteritidis. Analysis showed four of the major S. Enteritidis clades were represented, two global and two African. All thirteen DCS isolates, containing a single gyrA mutation at codon 87, belonged to a global PT4-like clade responsible for epidemics of poultry-associated enterocolitis. Apart from two DCS isolates, which clustered with PHE isolates associated with travel to Spain and Brazil, the remaining DCS isolates, including one poultry isolate, belonged to two monophyletic clusters in which gyrA 87 mutations appear to have developed within the region.

CONCLUSIONS/SIGNIFICANCE

Extensive phylogenetic diversity is evident amongst iNTS disease-associated S. Enteritidis in Ghana. Antimicrobial resistance profiles differed by clade, highlighting the challenges of devising empirical sepsis guidelines. The detection of fluoroquinolone resistance in phyletically-related poultry and human isolates is of major concern and surveillance and control measures within the region's burgeoning poultry industry are required to protect a human population at high risk of iNTS disease.

An international outbreak of Salmonella enterica serotype Enteritidis linked to eggs from Poland: a microbiological and epidemiological study

BACKGROUND

Salmonella spp are a major cause of food-borne outbreaks in Europe. We investigated a large multi-country outbreak of Salmonella enterica serotype Enteritidis in the EU and European Economic Area (EEA).

METHODS

A confirmed case was defined as a laboratory-confirmed infection with the outbreak strains of S Enteritidis based on whole-genome sequencing (WGS), occurring between May 1, 2015, and Oct 31, 2018. A probable case was defined as laboratory-confirmed infection with S Enteritidis with the multiple-locus variable-number tandem repeat analysis outbreak profile. Multi-country epidemiological, trace-back, trace-forward, and environmental investigations were done. We did a case-control study including confirmed and probable cases and controls randomly sampled from the population registry (frequency matched by age, sex, and postal code). Odds ratios (ORs) for exposure rates between cases and controls were calculated with unmatched univariable and multivariable logistic regression.

FINDINGS

18 EU and EEA countries reported 838 confirmed and 371 probable cases. 509 (42%) cases were reported in 2016, after which the number of cases steadily increased. The case-control study results showed that cases more often ate in food establishments than did controls (OR 3·4 [95% CI 1·6-7·3]), but no specific food item was identified. Recipe-based food trace-back investigations among cases who ate in food establishments identified eggs from Poland as the vehicle of infection in October, 2016. Phylogenetic analysis identified two strains of S Enteritidis in human cases that were subsequently identified in salmonella-positive eggs and primary production premises in Poland, confirming the source of the outbreak. After control measures were implemented, the number of cases decreased, but increased again in March, 2017, and the increase continued into 2018.

INTERPRETATION

This outbreak highlights the public health value of multi-country sharing of epidemiological, trace-back, and microbiological data. The re-emergence of cases suggests that outbreak strains have continued to enter the food chain, although changes in strain population dynamics and fewer cases indicate that control measures had some effect. Routine use of WGS in salmonella surveillance and outbreak response promises to identify and stop outbreaks in the future.

FUNDING

European Centre for Disease Prevention and Control; Directorate General for Health and Food Safety, European Commission; and National Public Health and Food Safety Institutes of the authors' countries (see Acknowledgments for full list).

Model-based biotechnological potential analysis of Kluyveromyces marxianus central metabolism

The non-conventional yeast Kluyveromyces marxianus is an emerging industrial producer for many biotechnological processes. Here, we show the application of a biomass-linked stoichiometric model of central metabolism that is experimentally validated, and mass and charge balanced for assessing the carbon conversion efficiency of wild type and modified K. marxianus. Pairs of substrates (lactose, glucose, inulin, xylose) and products (ethanol, acetate, lactate, glycerol, ethyl acetate, succinate, glutamate, phenylethanol and phenylalanine) are examined by various modelling and optimisation methods. Our model reveals the organism's potential for industrial application and metabolic engineering. Modelling results imply that the aeration regime can be used as a tool to optimise product yield and flux distribution in K. marxianus. Also rebalancing NADH and NADPH utilisation can be used to improve the efficiency of substrate conversion. Xylose is identified as a biotechnologically promising substrate for K. marxianus.

Predicting serious complications and high cost of treatment of tooth-knuckle injuries: a systematic literature review

PURPOSE

The tooth-knuckle injury (TKI) is a serious and potentially costly injury seen in orthopaedic practice. The aim was to conduct a systematic literature review on the factors associated with serious complications and high treatment costs in tooth-knuckle injuries.

METHODS

MEDLINE, Scopus and CINAHL were used as the literature sources.

INCLUSION CRITERIA

Original research papers that reported on factors predicting serious complications and high treatment costs in TKIs were included. There were no restrictions placed on study size, language, study design or date of publication.

EXCLUSION CRITERIA

Case studies, case series and review articles were not included.

RESULTS

After duplicates were removed, 403 unique studies remained; after titles and abstracts were screened, 48 titles remained and were retrieved in full text. Of these, 14 titles met the inclusion criteria and were included in the data synthesis. Tenosynovitis, septic arthritis, osteomyelitis and residual stiffness were common serious complications occurring in up to 36.3, 70.0, 47.6 and 65.3 % of cases, respectively. Amputation was also common in up to 18.0 % of injuries. Treatment costs were measured by length of hospital stay and the number of debridements required. On average, patients required 3.8-8 days of admission and 1.3-2.7 debridements each.

CONCLUSION

Increased time delay from injury to treatment, deeply penetrating injuries, proximal interphalangeal joint (PIPJ) injuries and, possibly, E. corrodens infections were associated with serious complications in TKIs. Delayed treatment, inadequate treatment, PIPJ injuries and deeply penetrating injuries predicted higher treatment costs.

SYSTEMATIC REVIEW REGISTRATION NUMBER

PROSPERO CRD42016029949 ( http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42016029949 ).

Identification of metabolic pathways essential for fitness of Salmonella Typhimurium in vivo

Bacterial infections remain a threat to human and animal health worldwide, and there is an urgent need to find novel targets for intervention. In the current study we used a computer model of the metabolic network of Salmonella enterica serovar Typhimurium and identified pairs of reactions (cut sets) predicted to be required for growth in vivo. We termed such cut sets synthetic auxotrophic pairs. We tested whether these would reveal possible combined targets for new antibiotics by analyzing the performance of selected single and double mutants in systemic mouse infections. One hundred and two cut sets were identified. Sixty-three of these included only pathways encoded by fully annotated genes, and from this sub-set we selected five cut sets involved in amino acid or polyamine biosynthesis. One cut set (asnA/asnB) demonstrated redundancy in vitro and in vivo and showed that asparagine is essential for S. Typhimurium during infection. trpB/trpA as well as single mutants were attenuated for growth in vitro, while only the double mutant was a cut set in vivo, underlining previous observations that tryptophan is essential for successful outcome of infection. speB/speF,speC was not affected in vitro but was attenuated during infection showing that polyamines are essential for virulence apparently in a growth independent manner. The serA/glyA cut-set was found to be growth attenuated as predicted by the model. However, not only the double mutant, but also the glyA mutant, were found to be attenuated for virulence. This adds glycine production or conversion of glycine to THF to the list of essential reactions during infection. One pair (thrC/kbl) showed true redundancy in vitro but not in vivo demonstrating that threonine is available to the bacterium during infection. These data add to the existing knowledge of available nutrients in the intra-host environment, and have identified possible new targets for antibiotics.

Promoting cancer control training in resource limited environments: Lagos, Nigeria

In resource limited nations, cancer control is often a lower priority issue creating challenges for the prevention, early diagnosis, and treatment of cancer. Training and education are vital components of efforts to tackle this problem. A 3-day cancer control workshop was conducted at the Lagos State University Teaching Hospital (LASUTH), Nigeria, in 2013. The curriculum included didactic lectures, panel discussions, and interactive sessions on local cancer statistics, preventive strategies, cancer registries, screening and diagnostic options, and treatment approaches with limited resources (chemotherapy, radiotherapy, surgery, and palliative care) and several site-specific (breast, lung, cervical, prostate, and colon) topics. Pre-workshop and post-workshop questionnaires were completed by participants. Eighty-six percent of the 50 workshop participants completed at least one questionnaire. Participants were mainly nurses and physicians (89% of responders), and 40% reported >25 years of practice experience. The more common local needs identified were professional education (65%) and increasing public cancer awareness (63%). The greatest interest for future programs was on research collaborations (70%). An immediate impact of the workshop was the commencement of monthly tumor board conferences and a review of the current cancer registry data. Capacity building is critical for the execution of effective cancer control strategies. Conducting collaborative workshops represents a cost-effective means of launching programs and energizing the medical community to pursue ongoing education and research addressing the anticipated cancer epidemic on the African continent.

First storage of ion beams in the Double Electrostatic Ion-Ring Experiment: DESIREE

We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (C(n)(-), n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C2 (-) molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s ± 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10(-14) mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.

P-selectin mediates neutrophil rolling and recruitment in acute pancreatitis

BACKGROUND

The adhesive mechanisms regulating leucocyte-endothelium interactions in the pancreas remain elusive, but selectins may play a role. This study examined the molecular mechanisms mediating leucocyte rolling along the endothelium in the pancreas and the therapeutic potential of targeting the rolling adhesive interaction in acute pancreatitis (AP).

METHODS

Pancreatitis was induced by retrograde infusion of 5 per cent sodium taurocholate into the pancreatic duct, repeated intraperitoneal administration of caerulein (50 µg/kg) or intraperitoneal administration of L-arginine (4 g/kg) in C57BL/6 mice. A control and a monoclonal antibody against P-selectin were administered before and after induction of AP. Serum and tissue were sampled to assess the severity of pancreatitis, and intravital microscopy was used to study leucocyte rolling.

RESULTS

Taurocholate infusion into the pancreatic duct increased the serum level of trypsinogen, trypsinogen activation, pancreatic neutrophil infiltration, macrophage inflammatory protein (MIP) 2 formation and tissue damage. Immunoneutralization of P-selectin decreased the taurocholate-induced increase in serum trypsinogen (median (range) 17·35 (12·20-30·00) versus 1·55 (0·60-15·70) µg/l; P = 0·017), neutrophil accumulation (4·00 (0·75-4·00) versus 0·63 (0-3·25); P = 0·002) and tissue damage, but had no effect on MIP-2 production (14·08 (1·68-33·38) versus 3·70 (0·55-51·80) pg/mg; P = 0·195) or serum trypsinogen activating peptide level (1·10 (0·60-1·60) versus 0·45 (0-1·80) µg/l; P = 0·069). Intravital fluorescence microscopy revealed that anti-P-selectin antibody inhibited leucocyte rolling completely in postcapillary venules of the inflamed pancreas.

CONCLUSION

Inhibition of P-selectin protected against pancreatic tissue injury in experimental pancreatitis. Targeting P-selectin may be an effective strategy to ameliorate inflammation in AP.

Rho-kinase signalling regulates trypsinogen activation and tissue damage in severe acute pancreatitis

BACKGROUND AND PURPOSE

Severe acute pancreatitis (SAP) is characterized by trypsinogen activation, infiltration of leucocytes and tissue necrosis but the intracellular signalling mechanisms regulating organ injury in the pancreas remain elusive. Rho-kinase is a potent regulator of specific cellular processes effecting several pro-inflammatory activities. Herein, we examined the role of Rho-kinase signalling in acute pancreatitis.

EXPERIMENTAL APPROACH

Pancreatitis was induced by infusion of taurocholate into the pancreatic duct in C57BL/6 mice. Animals were treated with a Rho-kinase inhibitor Y-27632 (0.5-5 mg·kg⁻¹) before induction of pancreatitis.

KEY RESULTS

Taurocholate infusion caused a clear-cut increase in blood amylase, pancreatic neutrophil infiltration, acinar cell necrosis and oedema formation in the pancreas. Levels of pancreatic myeloperoxidase (MPO), macrophage inflammatory protein-2 (MIP-2), trypsinogen activation peptide (TAP) and lung MPO were significantly increased, indicating local and systemic disease. Inhibition of Rho-kinase activity dose-dependently protected against pancreatitis. For example, 5 mg·kg⁻¹ Y-27632 reduced acinar cell necrosis, leucocyte infiltration and pancreatic oedema by 90%, 89% and 58%, respectively, as well as tissue levels of MPO by 75% and MIP-2 by 84%. Moreover, Rho-kinase inhibition decreased lung MPO by 75% and blood amylase by 83%. Pancreatitis-induced TAP levels were reduced by 61% in Y-27632-treated mice. Inhibition of Rho-kinase abolished secretagogue-induced activation of trypsinogen in pancreatic acinar cells in vitro.

CONCLUSIONS AND IMPLICATIONS

Our novel data suggest that Rho-kinase signalling plays an important role in acute pancreatitis by regulating trypsinogen activation and subsequent CXC chemokine formation, neutrophil infiltration and tissue injury. Thus, these results indicate that Rho-kinase may constitute a novel target in the management of SAP.

Role of platelets in experimental acute pancreatitis

BACKGROUND

Platelets not only control thrombosis and haemostasis but may also regulate inflammatory processes. Acute pancreatitis (AP) is characterized by changes in both coagulation and proinflammatory activities. The role of platelets in AP is not yet known.

METHODS

AP was induced in C57BL/6 mice by repeated caerulein administration (50 µg/kg intraperitoneally). Mice received a platelet-depleting or control antibody before caerulein challenge. Neutrophil infiltration, myeloperoxidase (MPO) and macrophage inflammatory protein (MIP) 2 levels, acinar cell necrosis and haemorrhage in the pancreas, as well as serum amylase activity, were determined 24 h after caerulein injection. In an alternative model of pancreatitis, L-arginine (4 g/kg intraperitoneally) was given twice with an interval of 1 h and tissue samples were taken after 72 h [Correction added after online publication 29 September 2010: in the preceding sentence, 4 mg/kg was corrected to 4 g/kg].

RESULTS

Caerulein administration increased acinar cell necrosis, neutrophil infiltration, focal haemorrhage and serum amylase levels. Platelet depletion reduced acinar cell necrosis, haemorrhage and serum amylase levels in AP. Depletion of platelets decreased caerulein-induced MPO levels and neutrophil recruitment in the pancreas. Platelet depletion abolished caerulein-induced MIP-2 generation in the pancreas and circulation. The effects of platelet depletion on necrosis, neutrophils and MPO levels were confirmed in L-arginine-induced pancreatitis.

CONCLUSION

Platelets play a crucial role in AP by regulating neutrophil infiltration, most likely mediated by MIP-2 production in the pancreas.

Partial androgen suppression consequent to increased secretion of adrenal androgens in a patient with prostate cancer treated with long-acting GnRH agonists

We present a case report of a patient with prostate cancer who failed to demonstrate consistent testosterone suppression to castration levels and incomplete suppression of serum prostate-specific antigen, although treated with gonadotropin releasing hormone agonists for 48 months. Serum dehydroepiandrosterone, dehydroepiandrosterone sulphate, as well as the androgen metabolite, androsterone glucuronide, were elevated compared to the other patients. The present data suggest that those prostate cancer patients who have even marginally elevated adrenal androgens may especially benefit from combined androgen blockade.

Coevolutionary arms races between bacteria and bacteriophage

We propose a computational and theoretical framework for analyzing rapid coevolutionary dynamics of bacteriophage and bacteria in their ecological context. Bacteriophage enter host cells via membrane-bound surface receptors often responsible for nutrient uptake. As such, a selective pressure will exist for the bacteria to modify its receptor configuration and, in turn, for the phage to modify its tail fiber. A mathematical model of these trait adaptations is developed by using the framework of adaptive dynamics. Host strains differ in their efficiency of resource uptake and resistance to phage, whereas phage strains differ in their host preference for adsorption. We solve the evolutionary ecology model and find the conditions for coevolutionary branching and relevant dimensionless parameters leading to distinct quasispecies. We confirm these calculations using stochastic Monte Carlo simulations of populations evolving in a chemostat with fixed washout rate and inflow resource density. We find that multiple quasispecies of bacteria and phage can coexist in a homogeneous medium with a single resource. When diversification occurs, quasispecies of phage adsorb effectively to only a limited subset of the total number of quasispecies of bacteria, i.e., functional differences between quasispecies arise endogenously within the evolutionary ecology framework. Finally, we discuss means to relate predictions of this model to experimental studies in the chemostat, using the model organisms Escherichia coli and the virulent strain of lambda phage.

Modeling the effect of analyte and reference bandwidths on signal and noise magnitudes in spectrophotometric assays

In spectrophotometric assays, it has been well established that the recorded absorption, and therefore the experimentally determined extinction coefficient, decreases as a function of detected bandwidth. This manuscript presents an expression for the extinction coefficient as a function of the critical parameter detected bandwidth per transition linewidth. Calculations for both single channel and multichannel photodetection are presented; the derived expressions are shown to be in good agreement with experimental results. It is important to realize that this systematic bias is present in dilute solutions of low absorptivity, and the experimentally recorded extinction coefficient for a molecular standard such as caffeine can vary approximately 4% or more, depending upon choice of research instrumentation. The magnitude of this bias may be sufficient to effect method robustness, cause interlaboratory discrepancies, and fail system suitability requirements for spectrophotometric assays. The signal to noise ratio, for example as analyzed in HPLC/UV-VIS detected chromatograms, is also a function of the detected bandwidths of both the analyte and reference channels. It is shown here that use of a reference can only increase the baseline noise.

Effects of prior apparatus experience and novelty of testing environment on locomotor activity following MK-801

Robust increases in locomotor activity are observed following administration of dizocilpine maleate (MK-801). The present study investigated the effects of prior apparatus experience and manipulation of the testing environment on locomotor activity following peripheral MK-801. Gerbils were given zero or nine sessions of apparatus exposure prior to testing with MK-801 (0.1 mg/kg ip) or saline. Sessions were 10 min in duration and separated by 24 h. As previously reported, naive animals treated with MK-801 were significantly more active relative to controls. Exposure to the apparatus for nine sessions resulted in a significant reduction in MK-801-induced activity, but did not alter the activity levels of control animals. To evaluate the effect of changes to the testing environment, animals previously evaluated in the familiar condition were retested in the identical apparatus relocated to a novel experimental room. MK-801-treated animals exhibited a significant increase in activity when tested in this novel environment while the locomotor activity of control gerbils was not significantly altered. The results illustrate the importance of repetitive testing and environmental changes as moderating variables in studies that evaluate locomotor activity. These data also indicate that the effects of MK-801 on activity are sensitive to prior experience with the apparatus and the novelty of the testing environment.

Hydrogen peroxide and the evolution of oxygenic photosynthesis

The early atmosphere of the Earth is considered to have been reducing (H2 rich) or neutral (CO2-N2). The present atmosphere by contrast is highly oxidizing (20% O2). The source of this oxygen is generally agreed to have been oxygenic photosynthesis, whereby organisms use water as the electron donor in the production of organic matter, liberating oxygen into the atmosphere. A major question in the evolution of life is how oxygenic photosynthesis could have evolved under anoxic conditions--and also when this capability evolved. It seems unlikely that water would be employed as the electron donor in anoxic environments that were rich in reducing agents such as ferrous or sulfide ions which could play that role. The abiotic production of atmospheric oxidants could have provided a mechanism by which locally oxidizing conditions were sustained within spatially confined habitats thus removing the available reductants and forcing photosynthetic organisms to utilize water as the electron donor. We suggest that atmospheric H2O2 played the key role in inducing oxygenic photosynthesis because as peroxide increased in a local environment, organisms would not only be faced with a loss of reductant, but they would also be pressed to develop the biochemical apparatus (e.g., catalase) that would ultimately be needed to protect against the products of oxygenic photosynthesis. This scenario allows for the early evolution of oxygenic photosynthesis while global conditions were still anaerobic.

The origin of the eukaryotic cell

The endosymbiotic hypothesis for the origin of the eukaryotic cell has been applied to the origin of the mitochondria and chloroplasts. However as has been pointed out by Mereschowsky in 1905, it should also be applied to the nucleus as well. If the nucleus, mitochondria and chloroplasts are endosymbionts, then it is likely that the organism that did the engulfing was not a DNA-based organism. In fact, it is useful to postulate that this organism was a primitive RNA-based organism. This hypothesis would explain the preponderance of RNA viruses found in eukaryotic cells. The centriole and basal body do not have a double membrane or DNA. Like all MTOCs (microtubule organising centres), they have a structural or morphic RNA implicated in their formation. This would argue for their origin in the early RNA-based organism rather than in an endosymbiotic event involving bacteria. Finally, the eukaryotic cell uses RNA in ways quite unlike bacteria, thus pointing to a greater emphasis of RNA in both control and structure in the cell. The origin of the eukaryotic cell may tell us why it rather than its prokaryotic relative evolved into the metazoans who are reading this paper.

Lifetime measurements of metastable states in Fe+

The lifetime of two metastable levels in Fe+ has been measured by laser probing of a stored ion beam. In the dense spectrum of Fe+, the metastable levels a (6)S(5/2) and b (4)D(7/2) were selected and their lifetimes were determined to be 230 +/- 30 and 530 +/- 30 ms, respectively. The lifetimes are compared with previous theoretical results. Metastable lifetime measurements of Fe+ are of great importance for interpretation of spectra from astronomical objects. The present experiment opens for the possibilities to investigate lifetimes of metastable states in complex atomic ions, which have, so far, been unexplored.

Alteration of dopamine metabolites in CSF and behavioral impairments induced by neonatal hippocampal lesions

Alterations of monoamine metabolites in CSF and behavioral abnormalities were studied in rats with neonatal hippocampal lesions and controls. Lesions of the ventral hippocampus were produced bilaterally by ibotenic acid on postnatal day 7. Lesion-induced neurochemical alterations and behavioral impairments were examined concurrently when rats were 12 weeks old. CSF from the cisterna magna was sampled repeatedly from freely moving rats. The levels of free 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxyindoleacetic acid (5-HIAA) in CSF were determined. An exposure to a novel environment induced hyperexploratory behavior and elevated the level of free DOPAC in CSF in lesioned rats. Although a swim stress increased the levels of free DOPAC and 5-HIAA in CSF in both control and lesioned groups, rats with hippocampal lesions had a further elevation of free DOPAC in CSF and greater spontaneous activity relative to controls shortly after stress. Amphetamine (1.5 mg/kg, i.p.) induced hyperlocomotion in lesioned rats compared to controls. For the control group, the levels of the three monoamine metabolites in CSF were not significantly influenced by amphetamine. However, for the lesioned group, the level of DOPAC significantly decreased compared to preinjection of amphetamine. The results indicate that neonatal hippocampal lesion-induced impairments can be manifested by behavioral and neurochemical abnormalities. Alterations of monoamine metabolites in CSF may be determined quantitatively and used as indices for monitoring lesion-impaired monoaminergic function in the central nervous system.

Photosynthesis and the origin of life

The origin and evolution of photosynthesis is considered to be the key to the origin of life. This eliminates the need for a soup as the synthesis of the bioorganics are to come from the fixation of carbon dioxide and nitrogen. No soup then no RNA world or Protein world. Cyanobacteria have been formed by the horizontal transfer of green sulfur bacterial photoreaction center genes by means of a plasmid into a purple photosynthetic bacterium. The fixation of carbon dioxide is considered to have evolved from a reductive dicarboxylic acid cycle (Chloroflexus) which was then followed by a reductive tricarboxylic acid cycle (Chlorobium) and finally by the reductive pentose phosphate cycle (Calvin cycle). The origin of life is considered to have occurred in a hot spring on the outgassing early earth. The first organisms were self-replicating iron-rich clays which fixed carbon dioxide into oxalic and other dicarboxylic acids. This system of replicating clays and their metabolic phenotype then evolved into the sulfide rich region of the hotspring acquiring the ability to fix nitrogen. Finally phosphate was incorporated into the evolving system which allowed the synthesis of nucleotides and phospholipids. If biosynthesis recapitulates biopoesis, then the synthesis of amino acids preceded the synthesis of the purine and pyrimidine bases. Furthermore the polymerization of the amino acid thioesters into polypeptides preceded the directed polymerization of amino acid esters by polynucleotides. Thus the origin and evolution of the genetic code is a late development and records the takeover of the clay by RNA.

The origin and evolution of oxygenic photosynthesis

The evolutionary developments that led to the ability of photosynthetic organisms to oxidize water to molecular oxygen are discussed. Two major changes from a more primitive non-oxygen-evolving reaction center are required: a charge-accumulating system and a reaction center pigment with a greater oxidizing potential. Intermediate stages are proposed in which hydrogen peroxide was oxidized by the reaction center, and an intermediate pigment, similar to chlorophyll d, was present.

Speculations on the evolution of the genetic code IV. The evolution of the aminoacyl-tRNA synthetases

An evolutionary scheme is postulated in which a primitive code, involving only guanine and cytosine, would code for glycine(GG.), alanine(GC.), arginine(CG.) and proline(CC.). There evolves from this primitive code families of related amino acids as the code expands. The evolution of the aminoacyl-tRNA synthetases are considered to be indicators for the evolution of the genetic code. The postulated model for the evolution of the genetic code is used to give an evolutionary interpretation to the recent work on the structure and sequences of the aminoacyl-tRNA synthetases.

Speculations on the origin of the genetic code

The most primitive code is assumed to be a GC code: GG coding for glycine, CC coding for proline, GC coding for alanine, CG coding for "arginine." The genetic code is assumed to have originated with the coupling of glycine to its anticodon CC mediated by a copper-montmorillonite. The polymerization of polyproline followed when it was coupled to its anticodon GG. In this case the aminoacyl-tRNA synthetase was a copper-montmorillonite. The first membrane is considered to be a beta sheet formed from polyglycine. As the code grew more complicated, the alternative hydrophobic-hydrophilic polypeptide (alanine-"arginine") was coded for by the alternating CG copolymer. This alternating polypeptide (ala-"arg") began to function as both a primitive membrane and as an aminoacyl-tRNA synthetase. The evolution of protein structure is tightly coupled to the evolution of the membrane. The alpha helix was evolved as lipids became part of the structure of biological membranes. The membrane finally became the fluid mosaic structure that is now universal.

Oxygenic photosynthesis and the oxidation state of Mars

The oxidation state of the Earth's surface is one of the most obvious indications of the effect of life on this planet. The surface of Mars is highly oxidized, as evidenced by its red color, but the connection to life is less apparent. Two possibilities can be considered. First, the oxidant may be photochemically produced in the atmosphere. In this case the fundamental source of O2 is the loss of H2 to space and the oxidant produced is H2O2. This oxidant would accumulate on the surface and thereby destroy any organic material and other reductants to some depth. Recent models suggest that diffusion limits this depth to a few meters. An alternative source of oxgyen is biological oxygen production followed by sequestration of organic material in sediments--as on the Earth. In this case, the net oxidation of the surface was determined billions of years ago when Mars was a more habitable planet and oxidative conditions could persist to great depths, over 100 m. Below this must be a compensating layer of biogenic organic material. Insight into the nature of past sources of oxidation on Mars will require searching for organics in the Martian subsurface and sediments.

Effects of atypical antipsychotic agents on social behavior in rodents

There are numerous preclinical screening procedures that are predictive of clinical efficacy for the positive symptoms of schizophrenia but no assays for the negative symptoms such as social withdrawal. In the social interaction test in rats, the atypical antipsychotic drug clozapine (10.0 mg/kg) and two putative atypical agents risperidone (0.0625 mg/kg) and HP 873 (0.5 and 1.0 mg/kg) significantly increased social interaction behaviors between pairs of unfamiliar but not familiar rats. The benzodiazepine diazepam (1.25-5.0 mg/kg) increased social behaviors in both paradigms. Haloperidol, chlorpromazine, raclopride, and SCH23390 decreased social behaviors in these assays. In vitro receptor binding studies revealed that only clozapine, risperidone, and HP 873 displayed dopamine to serotonin affinity ratios for both D2/5-hydroxytryptamine2(5-HT2)/ and D1/5-HT1A of greater than or equal to 12.9 and 1.0, respectively. The present study suggests that antipsychotic agents that may be effective in social withdrawal can be identified in this modified social interaction paradigm. Further, our data suggests that a compound's effectiveness for the treatment of social withdrawal is at least in part due to its relative affinity for binding to dopamine D1 and serotonin 5-HT1A receptors.

Spinach thioredoxin m inhibits DNA synthesis in fertilized Xenopus eggs

A role for thioredoxin in metazoan DNA synthesis has been assessed by injecting rapidly dividing Xenopus eggs with purified heterologous thioredoxins, which might act as inhibitors if they were to replace resident thioredoxins in some but not all reaction steps. Of 10 tested proteins, spinach chloroplast thioredoxin m is the most potent inhibitor. Eggs cleave and produce cells lacking nuclei. DNA synthesis is severely reduced. Development arrests before gastrulation. In egg extracts, thioredoxin m inhibits incorporation of radioactive dCTP into DNA of sperm nuclei and M13 phage. Inhibition exceeds 90% when thioredoxin m and M13 DNA are preincubated together. The data support the interpretation that thioredoxins normally participate in initiation of metazoan DNA synthesis.

Conjectures and reveries

The origin of photosynthesis is speculated to have involved carbon dioxide and self-replicating iron-rich clays. The later evolution of photosynthesis is considered to have undergone four distinct phases: (1) The photoreduction of carbon dioxide by ferrous ion to form oxalate and formate. (2) The entry of sulfur into the evolving clay system which led to the formation of acetyl thioesters. The polymerization of the acetyl thioeters led to the formation of quinones. The formation of Fe2S2 and Fe4S4 cores appeared in this phase. (3) The ability to fix nitrogen characterized the third phase. This led to the formation of pyrrole, flavin, nicotinamide, phycobilins, porphyrins and chlorophyll. (4) Finally, phosphate entered the evolving system.The chromophores evolved from ferrous ion through the quinones, carotenoids, phycobilins to chlorophyll. This evolution of chromophores implies that photosynthesis began in the UV and evolved through the blue, yellow, orange into the red. The electron transport chain evolved from ferrous ion through the Fe2S2 and Fe4S4 cores to the hemes.